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Sample records for frequency reactive magnetron

  1. Facing-target mid-frequency magnetron reactive sputtered hafnium oxide film: Morphology and electrical properties

    NASA Astrophysics Data System (ADS)

    Zhang, Yu; Xu, Jun; Wang, You-Nian; Choi, Chi Kyu; Zhou, Da-Yu

    2016-03-01

    Amorphous hafnium dioxide (HfO2) film was prepared on Si (100) by facing-target mid-frequency reactive magnetron sputtering under different oxygen/argon gas ratio at room temperature with high purity Hf target. 3D surface profiler results showed that the deposition rates of HfO2 thin film under different O2/Ar gas ratio remain unchanged, indicating that the facing target midfrequency magnetron sputtering system provides effective approach to eliminate target poisoning phenomenon which is generally occurred in reactive sputtering procedure. X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR) demonstrated that the gradual reduction of oxygen vacancy concentration and the densification of deposited film structure with the increase of oxygen/argon (O2/Ar) gas flow ratio. Atomic force microscopy (AFM) analysis suggested that the surface of the as-deposited HfO2 thin film tends to be smoother, the root-meansquare roughness (RMS) reduced from 0.876 nm to 0.333 nm while O2/Ar gas flow ratio increased from 1/4 to 1/1. Current-Voltage measurements of MOS capacitor based on Au/HfO2/Si structure indicated that the leakage current density of HfO2 thin films decreased by increasing of oxygen partial pressure, which resulted in the variations of pore size and oxygen vacancy concentration in deposited thin films. Based on the above characterization results the leakage current mechanism for all samples was discussed systematically.

  2. Development of mid-frequency AC reactive magnetron sputtering for fast deposition of Y2O3 buffer layers

    NASA Astrophysics Data System (ADS)

    Xiong, Jie; Xia, Yudong; Xue, Yan; Zhang, Fei; Guo, Pei; Zhao, Xiaohui; Tao, Bowan

    2014-02-01

    A reel-to-reel magnetron sputtering system with mid-frequency alternating current (AC) power supply was used to deposit double-sided Y2O3 seed layer on biaxially textured Ni-5 at.%W tape for YBa2Cu3O7-δ coated conductors. A reactive sputtering process was carried out using two opposite symmetrical sputtering guns with metallic yttrium targets and water vapor for oxidizing the sputtered metallic atoms. The voltage control mode of the power supply was used and the influence of the cathode voltage and ArH2 pressure were systematically investigated. Subsequently yttrium-stabilized zirconia (YSZ) barrier and CeO2 cap layers were deposited on the Y2O3 buffered substrates in sequence, indicating high quality and uniform double-sided structure and surface morphology of such the architecture.

  3. Reactive high power impulse magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Gudmundsson, J. T.; Magnus, F.; Tryggvason, T. K.; Sveinsson, O. B.; Olafsson, S.

    2012-10-01

    Here we discuss reactive high power impulse magnetron sputtering sputtering (HiPIMS) [1] of Ti target in an Ar/N2 and Ar/O2 atmosphere. The discharge current waveform is highly dependent on both the pulse repetition frequency and discharge voltage. The discharge current increases with decreasing frequency or voltage. This we attribute to an increase in the secondary electron emission yield during the self-sputtering phase of the pulse, as nitride [2] or oxide [3] forms on the target. We also discuss the growth of TiN films on SiO2 at temperatures of 22-600 ^oC. The HiPIMS process produces denser films at lower growth temperature and the surface is much smoother and have a significantly lower resistivity than dc magnetron sputtered films on SiO2 at all growth temperatures due to reduced grain boundary scattering [4].[4pt] [1] J. T. Gudmundsson, N. Brenning, D. Lundin and U. Helmersson, J. Vac. Sci. Technol. A, 30 030801 (2012)[0pt] [2] F. Magnus, O. B. Sveinsson, S. Olafsson and J. T. Gudmundsson, J. Appl. Phys., 110 083306 (2011)[0pt] [3] F. Magnus, T. K. Tryggvason, S. Olafsson and J. T. Gudmundsson, J. Vac. Sci. Technol., submitted 2012[0pt] [4] F. Magnus, A. S. Ingason, S. Olafsson and J. T. Gudmundsson, IEEE Elec. Dev. Lett., accepted 2012

  4. Formation of dielectric silicon compounds by reactive magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Veselov, D. S.; Voronov, Yu A.

    2016-09-01

    The paper is devoted to the study of reactive magnetron sputtering of the silicon target in the ambient of inert argon gas with reactive gas, nitrogen or oxygen. The magnetron was powered by two mid-frequency generators of a rectangular pulse of opposite polarity. The negative polarity pulse provides the sputtering of the target. The positive polarity pulse provides removal of accumulated charge from the surface of the target. This method does not require any special devices of resistances matching and provides continuous sputtering of the target.

  5. Modeling of the Reactive High Power Impulse Magnetron Sputtering (HiPIMS) process

    NASA Astrophysics Data System (ADS)

    Gudmundsson, Jon Tomas; Lundin, Daniel; Raadu, Michael; Brenning, Nils; Minea, Tiberiu

    2015-09-01

    Reactive high power impulse magnetron sputtering (HiPIMS) provides both a high ionization fraction of the sputtered material and a high dissociation fraction of the molecular gas. We demonstrate this through an ionization region model (IRM) of the reactive Ar/O2 HiPIMS discharge with a titanium target. We explore the influence of oxygen dilution on the discharge properties such as electron density, the ionization fraction of the sputtered vapor and the oxygen dissociation fraction. We discuss the important processes and challenges for more detailed modeling of the reactive HiPIMS discharge. Furthermore, we discuss experimental observations during reactive high power impulse magnetron sputtering sputtering (HiPIMS) of Ti target in Ar/N2 and Ar/O2 atmosphere. The discharge current waveform is highly dependent on the reactive gas flow rate, pulse repetition frequency and discharge voltage. The discharge current increases with decreasing repetition frequency and increasing flowrate of the reactive gas.

  6. Reactive pulsed magnetron-sputtered tantalum oxide thin films

    NASA Astrophysics Data System (ADS)

    Nielsen, Matthew Christian

    Current high speed, advanced packaging applications require the use of integrated capacitors. Tantalum oxide is one material currently being considered for use in the capacitors; however, the deposition technique used to make the thin film dielectric can alter its performance. Pulsed magnetron reactive sputtering was investigated in this thesis as it offers a robust, clean, and low temperature deposition alternative. This is a new deposition technique created to control the negative effects of target poisoning; however, to understand the relationships between the deposition variables and the resultant film properties a thorough investigation is needed. The instantaneous voltage at the target was captured using a high speed digital oscilloscope. Three target oxidation states were imaged and identified to be that of the metallic and oxidized states with an abrupt transition region separating the two. Using high resolution X-ray photoelectron spectroscopy the bonding present in the deposited films was correlated to the oxidation state of the target. While operating the target in the metallic mode, a mix of oxidized, sub-oxide and metallic states were discovered. Alternatively, the bonding present in the films deposited when the target was in the oxidized state were that of fully oxidized tantalum pentoxide. The films deposited above the critical partial pressure demonstrated excellent leakage current densities. The exact magnitude of the leakage current density inversely scaled to the relative amount of oxygen included into the sputtering atmosphere. Detailed plot analysis showed that there were two different conduction mechanisms controlling the current flow in the capacitors. High frequency test vehicles were measured up to 10 GHz in order to determine the frequency response of the dielectric material. A circuit equivalent model describing the testing system and samples was created and utilized to fit the collected data. Overall, the technique of pulsed magnetron

  7. Phase and Frequency Locked Magnetrons for SRF Sources

    SciTech Connect

    Neubauer, M.; Johnson, R.P.; Popovic, M.; Moretti, A.; /Fermilab

    2009-05-01

    Magnetrons are low-cost highly-efficient microwave sources, but they have several limitations, primarily centered about the phase and frequency stability of their output. When the stability requirements are low, such as for medical accelerators or kitchen ovens, magnetrons are the very efficient power source of choice. But for high energy accelerators, because of the need for frequency and phase stability - proton accelerators need 1-2 degrees source phase stability, and electron accelerators need .1-.2 degrees of phase stability - they have rarely been used. We describe a novel variable frequency cavity technique which will be utilized to phase and frequency lock magnetrons.

  8. Reactive high power impulse magnetron sputtering: combining simulation and experiment

    NASA Astrophysics Data System (ADS)

    Kozak, Tomas; Vlcek, Jaroslav

    2016-09-01

    Reactive high-power impulse magnetron sputtering (HiPIMS) has recently been used for preparation of various oxide films with high application potential, such as TiO2, ZrO2, Ta2O5, HfO2, VO2. Using our patented method of pulsed reactive gas flow control with an optimized reactive gas inlet, we achieved significantly higher deposition rates compared to typical continuous dc magnetron depositions. We have developed a time-dependent model of the reactive HiPIMS. The model includes a depth-resolved description of the sputtered target (featuring sputtering, implantation and knock-on implantation processes) and a parametric description of the discharge plasma (dissociation of reactive gas, ionization and return of sputtered atoms and gas rarefaction). The model uses a combination of experimental and simulation data as input. We have calculated the composition of the target and substrate for several deposition conditions. The simulations predict a reduced compound coverage of the target in HiPIMS compared to the continuous dc sputtering regime which explains the increased deposition rate. The simulations show that an increased dissociation of oxygen in a HiPIMS discharge is beneficial to achieve stoichiometric films on the substrate at high deposition rates.

  9. Elementary surface processes during reactive magnetron sputtering of chromium

    SciTech Connect

    Monje, Sascha; Corbella, Carles Keudell, Achim von

    2015-10-07

    The elementary surface processes occurring on chromium targets exposed to reactive plasmas have been mimicked in beam experiments by using quantified fluxes of Ar ions (400–800 eV) and oxygen atoms and molecules. For this, quartz crystal microbalances were previously coated with Cr thin films by means of high-power pulsed magnetron sputtering. The measured growth and etching rates were fitted by flux balance equations, which provided sputter yields of around 0.05 for the compound phase and a sticking coefficient of O{sub 2} of 0.38 on the bare Cr surface. Further fitted parameters were the oxygen implantation efficiency and the density of oxidation sites at the surface. The increase in site density with a factor 4 at early phases of reactive sputtering is identified as a relevant mechanism of Cr oxidation. This ion-enhanced oxygen uptake can be attributed to Cr surface roughening and knock-on implantation of oxygen atoms deeper into the target. This work, besides providing fundamental data to control oxidation state of Cr targets, shows that the extended Berg's model constitutes a robust set of rate equations suitable to describe reactive magnetron sputtering of metals.

  10. Phase and Frequency Locked Magnetrons for SRF Sources

    SciTech Connect

    Neubauer, Michael; Johnson, Rolland

    2014-09-12

    There is great potential for a magnetron power source that can be controlled both in phase and frequency. Such a power source could revolutionize many particle accelerator systems that require lower capital cost and/or higher power efficiency. Beyond the accelerator community, phase and frequency locked magnetons could improve radar systems around the world and make affordable phased arrays for wireless power transmission for solar powered satellites. This joint project of Muons, Inc., Fermilab, and L-3 CTL was supported by an STTR grant monitored by the Nuclear Physics Office of the DOE Office of Science. The object of the program was to incorporate ferrite materials into the anode of a magnetron and, with appropriate biasing of the ferrites, to maintain frequency lock and to allow for frequency adjustment of the magnetron without mechanical tuners. If successful, this device would have a dual use both as a source for SRF linacs and for military applications where fast tuning of the frequency is a requirement. In order to place the materials in the proper location, several attributes needed to be modeled. First the impact of the magnetron’s magnetic field needed to be shielded from the ferrites so that they were not saturated. And second, the magnetic field required to change the frequency of the magnetron at the ferrites needed to be shielded from the region containing the circulating electrons. ANSYS calculations of the magnetic field were used to optimize both of these parameters. Once the design for these elements was concluded, parts were fabricated and a complete test assembly built to confirm the predictions of the computer models. The ferrite material was also tested to determine its compatibility with magnetron tube processing temperatures. This required a vacuum bake out of the chosen material to determine the cleanliness of the material in terms of outgassing characteristics, and a subsequent room temperature test to verify that the characteristics of

  11. A frequency tunable relativistic magnetron with a wide operation regime

    NASA Astrophysics Data System (ADS)

    Shi, Di-Fu; Qian, Bao-Liang; Wang, Hong-Gang; Li, Wei; Du, Guang-Xing

    2017-02-01

    A frequency tunable relativistic magnetron (RM) with a wide operation regime is proposed. With the all cavity-magnetron axial extraction technique, the RM can output TEM mode with the operating frequency of 4.3 GHz, which is demonstrated as the dominating output mode by theoretical analysis, cold simulations and hot simulations respectively, corresponding to the output power of 466 MW and the power conversion efficiency of 56.4 %. It also can achieve a wide frequency tuning with the bandwidth of 0.96 GHz and the relative bandwidth of 20.8 %, corresponding to the output power of above 400 MW and the power conversion efficiency of above 40 %. Further simulation results show that the RM has strong performance robustness to the perturbations of the electrical parameters and almost all structural parameters except the cathode radius, anode radius and cavity radius, however two methods proposed in this paper can be taken to further improve the RM performance. The performance robustness enables the RM to operate with a wide parameter regime while keeping a good performance. In addition, a GW-level RM with the power conversion efficiency of 55.9 % also can be obtained.

  12. A kind of magnetron cavity used in rubidium atomic frequency standards

    NASA Astrophysics Data System (ADS)

    Shiyu, Yang; Jingzhong, Cui; Jianhui, Tu; Yaoting, Liang

    2011-12-01

    Research on the magnetron cavity used in the rubidium atomic frequency standards is developed, through which the main characteristic parameters of the magnetron cavity are studied, mainly including the resonant frequency, quality factor and oscillation mode. The resonant frequency and quality factor of the magnetron cavity were calculated, and the test results of the resonant frequency agreed well with the calculation theory. The test results also show that the resonant frequency of the magnetron cavity can be attenuated to 6.835 GHz, which is the resonant frequency of the rubidium atoms, and the Q-factor can be attenuated to 500-1000. The oscillation mode is a typical TE011 mode and is the correct mode needed for the rubidium atomic frequency standard. Therefore these derivative magnetron cavities meet the requirements of the rubidium atomic frequency standards well.

  13. Current-voltage-time characteristics of the reactive Ar/N{sub 2} high power impulse magnetron sputtering discharge

    SciTech Connect

    Magnus, F.; Sveinsson, O. B.; Olafsson, S.; Gudmundsson, J. T.

    2011-10-15

    The discharge current and voltage waveforms have been measured in a reactive high power impulse magnetron sputtering (HiPIMS) Ar/N{sub 2} discharge with a Ti target for 400 {mu}s long pulses. We observe that the current waveform in the reactive Ar/N{sub 2} HiPIMS discharge is highly dependent on the pulse repetition frequency, unlike the non-reactive Ar discharge. The current is found to increase significantly as the frequency is lowered. This is attributed to an increase in the secondary electron emission yield during the self-sputtering phase, when the nitride forms on the target at low frequencies. In addition, self-sputtering runaway occurs at lower discharge voltages when nitrogen is added to the discharge. This illustrates the crucial role of self-sputtering in the behavior of the reactive HiPIMS discharge.

  14. Silicon oxynitride films deposited by reactive high power impulse magnetron sputtering using nitrous oxide as a single-source precursor

    SciTech Connect

    Hänninen, Tuomas Schmidt, Susann; Jensen, Jens; Hultman, Lars; Högberg, Hans

    2015-09-15

    Silicon oxynitride thin films were synthesized by reactive high power impulse magnetron sputtering of silicon in argon/nitrous oxide plasmas. Nitrous oxide was employed as a single-source precursor supplying oxygen and nitrogen for the film growth. The films were characterized by elastic recoil detection analysis, x-ray photoelectron spectroscopy, x-ray diffraction, x-ray reflectivity, scanning electron microscopy, and spectroscopic ellipsometry. Results show that the films are silicon rich, amorphous, and exhibit a random chemical bonding structure. The optical properties with the refractive index and the extinction coefficient correlate with the film elemental composition, showing decreasing values with increasing film oxygen and nitrogen content. The total percentage of oxygen and nitrogen in the films is controlled by adjusting the gas flow ratio in the deposition processes. Furthermore, it is shown that the film oxygen-to-nitrogen ratio can be tailored by the high power impulse magnetron sputtering-specific parameters pulse frequency and energy per pulse.

  15. Observation of a periodic runaway in the reactive Ar/O{sub 2} high power impulse magnetron sputtering discharge

    SciTech Connect

    Shayestehaminzadeh, Seyedmohammad E-mail: shayesteh@mch.rwth-aachen.de; Arnalds, Unnar B.; Magnusson, Rögnvaldur L.; Olafsson, Sveinn

    2015-11-15

    This paper reports the observation of a periodic runaway of plasma to a higher density for the reactive discharge of the target material (Ti) with moderate sputter yield. Variable emission of secondary electrons, for the alternating transition of the target from metal mode to oxide mode, is understood to be the main reason for the runaway occurring periodically. Increasing the pulsing frequency can bring the target back to a metal (or suboxide) mode, and eliminate the periodic transition of the target. Therefore, a pulsing frequency interval is defined for the reactive Ar/O{sub 2} discharge in order to sustain the plasma in a runaway-free mode without exceeding the maximum power that the magnetron can tolerate.

  16. Correlation between the mechanical stress and microstructure in reactive bias magnetron sputtered silicon nitride films

    SciTech Connect

    Kim, J.H.; Lee, W.S.; Chung, K.W.

    1998-12-31

    The influence of ion bombardment on the mechanical stress and microstructure of sputtered silicon nitride (SiN{sub x}) films has been systematically investigated. Applied substrate bias voltage was used to control the bombardment energy in a radio frequency (rf) reactive magnetron sputtering system. The resultant films were characterized by transmission electron microscopy (TEM), atomic force microscopy (AFM), Fourier transform infrared spectroscopy (FT-IR), Rutherford backscattering spectrometry (RBS), stress and chemical etch rate measurements. As the bias voltage was increased, the internal stress in SiN{sub x} films became increasingly compressive and reached a value of about 18.3 {times} 10{sup 9} dyne cm{sup 2} at higher bias voltages. These correlated well with the transition of the film microstructure from a porous microcolumnar structure containing large void to the more densely packed one. The obtained results can be explained in terms of atomic peening by energetic particles, leading to densification of the microstructure. It was also found that the amount of argon incorporated in the film is increased with increasing bias voltage, whereas the oxygen content is decreased. The lowest etch rate in buffered HF solution, approximately 1.2 {angstrom}/sec, was observed with the application of a substrate bias of {minus}50 V.

  17. Time resolved ion energy distribution functions of non-reactive and reactive high power impulse magnetron sputtering of titanium

    NASA Astrophysics Data System (ADS)

    Grosse, Katharina; Breilmann, Wolfgang; Maszl, Christian; Benedikt, Jan; von Keudell, Achim

    2016-09-01

    High power impulse magnetron sputtering (HiPIMS) is a technique for thin film deposition and can be operated in reactive and non-reactive mode. The growth rate of HiPIMS in non-reactive mode reduces to 30% compared to direct current magnetron sputtering (dcMS) at same average power. However, the quality of the coatings produced with HiPIMS is excellent which makes these plasmas highly appealing. In reactive mode target poisoning is occurring which changes the plasma dynamics. An advantage of reactive HiPIMS is that it can be operated hysteresis-free which can result in a higher growth rate compared to dcMS. In this work thin films are deposited by a HiPIMS plasma which is generated by short pulses of 100 μs with high power densities in the range of 1 kW/cm2. Ar and Ar/N2 admixtures are used as a working gas to sputter a 2'' titanium target. The particle transport is analysed with time resolved ion energy distribution functions which are measured by a mass spectrometer with a temporal resolution of 2 μs. Phase resolved optical emission spectroscopy is executed to investigate the particle dynamics of different species. The time and energy resolved particle fluxes in non-reactive and reactive mode are compared and implications on the sputter process are discussed.

  18. Origin of particles during reactive sputtering of oxides using planar and cylindrical magnetrons.

    PubMed

    Rademacher, Daniel; Fritz, Benjamin; Vergöhl, Michael

    2012-03-01

    Particles generated during reactive magnetron sputtering cause defects in optical thin films, which may lead to losses in optical performance, pinholes, loss of adhesion, decreased laser-induced damage thresholds and many more negative effects. Therefore, it is important to reduce the particle contamination during the manufacturing process. In the present paper, the origin of particles during the deposition of various oxide films by midfrequency pulsed reactive magnetron sputtering was investigated. Several steps have been undertaken to decrease the particle contamination during the complete substrate handling procedure. It was found that conditioning of the vacuum chamber can help to decrease the defect level significantly. This level remains low for several hours of sputtering and increases after 100 hours of process time. Particle densities of SiO(2) films deposited with cylindrical and planar dual magnetrons at different process parameters as well as different positions underneath the target were compared. It was observed that the process power influences the particle density significantly in case of planar targets while cylindrical targets have no such strong dependence. In addition, the particle contamination caused by different cylindrical target materials was analyzed. No major differences in particle contamination of different cylindrical target types and materials were found.

  19. Titania, silicon dioxide, and tantalum pentoxide waveguides and optical resonant filters prepared with radio-frequency magnetron sputtering and annealing.

    PubMed

    Rabady, Rabi; Avrutsky, Ivan

    2005-01-20

    Mixing dielectric materials in solid-thin-film deposition allows the engineering of thin films' optical constants to meet specific thin-film-device requirements, which can be significantly useful for optoelectronics devices and photonics technologies in general. In principle, by use of radio-frequency (rf) magnetron sputtering, it would be possible to mix any two, or more, materials at different molar ratios as long as the mixed materials are not chemically reactive in the mixture. This freedom in material mixing by use of magnetron sputtering has an advantage by providing a wide range of the material optical constants, which eventually enables the photonic-device designer to have the flexibility to achieve optimal device performance. We deposited three combinations from three different oxides by using rf magnetron sputtering and later investigated them for their optical constants. Each two-oxide mixture was done at different molar ratio levels. Moreover, postdeposition annealing was investigated and was shown to reduce the optical losses and to stabilize the film composition against environmental effects such as aging and humidity exposure. These investigations were supported by the fabricated planar waveguides and optical resonant filters.

  20. Plasma reactivity in high-power impulse magnetron sputtering through oxygen kinetics

    SciTech Connect

    Vitelaru, Catalin; Lundin, Daniel; Brenning, Nils; Minea, Tiberiu

    2013-09-02

    The atomic oxygen metastable dynamics in a Reactive High-Power Impulse Magnetron Sputtering (R-HiPIMS) discharge has been characterized using time-resolved diode laser absorption in an Ar/O{sub 2} gas mixture with a Ti target. Two plasma regions are identified: the ionization region (IR) close to the target and further out the diffusion region (DR), separated by a transition region. The μs temporal resolution allows identifying the main atomic oxygen production and destruction routes, which are found to be very different during the pulse as compared to the afterglow as deduced from their evolution in space and time.

  1. Process stabilization by peak current regulation in reactive high-power impulse magnetron sputtering of hafnium nitride

    NASA Astrophysics Data System (ADS)

    Shimizu, T.; Villamayor, M.; Lundin, D.; Helmersson, U.

    2016-02-01

    A simple and cost effective approach to stabilize the sputtering process in the transition zone during reactive high-power impulse magnetron sputtering (HiPIMS) is proposed. The method is based on real-time monitoring and control of the discharge current waveforms. To stabilize the process conditions at a given set point, a feedback control system was implemented that automatically regulates the pulse frequency, and thereby the average sputtering power, to maintain a constant maximum discharge current. In the present study, the variation of the pulse current waveforms over a wide range of reactive gas flows and pulse frequencies during a reactive HiPIMS process of Hf-N in an Ar-N2 atmosphere illustrates that the discharge current waveform is a an excellent indicator of the process conditions. Activating the reactive HiPIMS peak current regulation, stable process conditions were maintained when varying the N2 flow from 2.1 to 3.5 sccm by an automatic adjustment of the pulse frequency from 600 Hz to 1150 Hz and consequently an increase of the average power from 110 to 270 W. Hf-N films deposited using peak current regulation exhibited a stable stoichiometry, a nearly constant power-normalized deposition rate, and a polycrystalline cubic phase Hf-N with (1 1 1)-preferred orientation over the entire reactive gas flow range investigated. The physical reasons for the change in the current pulse waveform for different process conditions are discussed in some detail.

  2. Theoretical investigation of frequency characteristics of free oscillation and injection-locked magnetrons

    NASA Astrophysics Data System (ADS)

    Yue, Song; Gao, Dong-ping; Zhang, Zhao-chuan; Wang, Wei-long

    2016-11-01

    The frequency characteristics of free oscillation magnetron (FOM) and injection-locked magnetron (ILM) are theoretically investigated. By using the equal power voltage obtained from the experiment data, expressions of the frequency and radio frequency (RF) voltage of FOM and ILM, as well as the locking bandwidth, on the anode voltage and magnetic field are derived. With the increase of the anode voltage and the decrease of the magnetic field, the power and its growth rate increase, while the frequency increases and its growth rate decreases. The theoretical frequency and power of FOM agree with the particle-in-cell (PIC) simulation results. Besides, the theoretical trends of the power and frequency with the anode voltage and magnetic field are consistent with the experimental results, which verifies the accuracy of the theory. The theory provides a novel calculation method of frequency characteristics. It can approximately analyze the power and frequency of both FOM and ILM, which promotes the industrial applications of magnetron and microwave energy. Project supported by the National Basic Research Program of China (Grant No. 2013CB328901) and the National Natural Science Foundation of China (Grant No. 11305177).

  3. Perspective: Is there a hysteresis during reactive High Power Impulse Magnetron Sputtering (R-HiPIMS)?

    NASA Astrophysics Data System (ADS)

    Strijckmans, K.; Moens, F.; Depla, D.

    2017-02-01

    This paper discusses a few mechanisms that can assist to answer the title question. The initial approach is to use an established model for DC magnetron sputter deposition, i.e., RSD2013. Based on this model, the impact on the hysteresis behaviour of some typical HiPIMS conditions is investigated. From this first study, it becomes clear that the probability to observe hysteresis is much lower as compared to DC magnetron sputtering. The high current pulses cannot explain the hysteresis reduction. Total pressure and material choice make the abrupt changes less pronounced, but the implantation of ionized metal atoms that return to the target seems to be the major cause. To further substantiate these results, the analytical reactive sputtering model is coupled with a published global plasma model. The effect of metal ion implantation is confirmed. Another suggested mechanism, i.e., gas rarefaction, can be ruled out to explain the hysteresis reduction. But perhaps the major conclusion is that at present, there are too little experimental data available to make fully sound conclusions.

  4. Charge Build-Up in Magnetron-Enhanced Reactive Ion Etching

    NASA Astrophysics Data System (ADS)

    Hoga, Hiroshi; Orita, Toshiyuki; Yokoyama, Takashi; Hayashi, Toshio

    1991-11-01

    Charge build-up in magnetron-enhanced reactive ion etching (MERIE) was evaluated with metal nitride oxide semiconductor (MNOS) capacitors. In static magnetic field, negative flat band voltage (Vfb) shifts of more than -1.5 V were observed in the area under high-density plasma, and more than 2-V Vfb shifts were observed at the edge of the wafer near the N and S poles. This distributed Vfb shift was considered to result from nonuniform plasma potential caused by secondary electron E× B drift motion. In rotated magnetic field, Vfb shifts were reduced. No significant Vfb shifts were observed when the magnet was rotated at 120 rpm. The Vfb shift reduction in rotated magnetic field was supposed to result from charge neutralization by alternate charge build-up.

  5. Manufacturing of HfOxNy films using reactive magnetron sputtering for ISFET application

    NASA Astrophysics Data System (ADS)

    Firek, Piotr; Wysokiński, Piotr

    2016-12-01

    Hafnium Oxide-Nitride films were deposited using reactive magnetron sputtering in O2/N2/Ar gas mixture. Deposition was planned according to Taguchi optimization method. Morphology of fabricated layers was tested using AFM technique (Ra=0.2÷1,0 nm). Thickness of HfOXNY films was measured using spectroscopic ellipsometry (t=45÷54 nm). Afterwards MIS structures were created by Al metallization process then layers were electrically characterised using I-V and C-V measurements. This allowed to calculate the electrical parameters of layers such as: flat-band voltage UFB, dielectric constant Ki, interface state trap density Dit and effective charge Qeff. Subsequently, deposited HfOxNy layers were annealed in PDA process (40 min 400 °C 100% N2) after which the electrical characterization was performed again.

  6. Structural-dependent thermal conductivity of aluminium nitride produced by reactive direct current magnetron sputtering

    SciTech Connect

    Belkerk, B. E.; Soussou, A.; Carette, M.; Djouadi, M. A.; Scudeller, Y.

    2012-10-08

    This Letter reports the thermal conductivity of aluminium nitride (AlN) thin-films deposited by reactive DC magnetron sputtering on single-crystal silicon substrates (100) with varying plasma and magnetic conditions achieving different crystalline qualities. The thermal conductivity of the films was measured at room temperature with the transient hot-strip technique for film thicknesses ranging from 100 nm to 4000 nm. The thermal conductivity was found to increase with the thickness depending on the synthesis conditions and film microstructure. The conductivity in the bulk region of the films, so-called intrinsic conductivity, and the boundary resistance were in the range [120-210] W m{sup -1} K{sup -1} and [2-30 Multiplication-Sign 10{sup -9}] K m{sup 2} W{sup -1}, respectively, in good agreement with microstructures analysed by x-ray diffraction, high-resolution-scanning-electron-microscopy, and transmission-electron-microscopy.

  7. Structural and thermal properties of nanocrystalline CuO synthesized by reactive magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Verma, M.; Gupta, V. K.; Gautam, Y. K.; Dave, V.; Chandra, R.

    2014-01-01

    Recent research has shown immense application of metal oxides like CuO, MgO, CaO, Al2O3, etc. in different areas which includes chemical warfare agents, medical drugs, magnetic storage media and solar energy transformation. Among the metal oxides, CuO nanoparticles are of special interest because of their excellent gas sensing and catalytic properties. In this paper we report structural and thermal properties of CuO synthesized by reactive magnetron DC sputtering. The synthesized nanoparticles were characterized by X-ray diffractometer. The XRD result reveals that as DC power increased from 30W to 80W, size of the CuO nanoparticles increased. The same results have been verified through TEM analysis. Thermal properties of these particles were studied using thermogravimetry.

  8. Studies on optoelectronic properties of DC reactive magnetron sputtered chromium doped CdO thin films

    SciTech Connect

    Hymavathi, B. Rao, T. Subba; Kumar, B. Rajesh

    2014-10-15

    Cr doped CdO thin films were deposited on glass substrates by DC reactive magnetron sputtering method and subsequently annealed from 200 °C to 500 °C. X-ray diffraction analysis showed that the films exhibit (1 1 1) preferred orientation. The optical transmittance of the films increases from 64% to 88% with increasing annealing temperature. The optical band gap values were found to be decreased from 2.77 to 2.65 eV with the increase of annealing temperature. The decrease in optical band gap energy with increasing annealing temperature can be attributed to improvement in the crystallinity of the films and may also be due to quantum confinement effect. A minimum resistivity of 2.23 × 10{sup −4} Ω.cm and sheet resistance of 6.3 Ω/sq is obtained for Cr doped CdO film annealed at 500 °C.

  9. Deposition of vanadium oxide films by direct-current magnetron reactive sputtering

    NASA Technical Reports Server (NTRS)

    Kusano, E.; Theil, J. A.; Thornton, John A.

    1988-01-01

    It is demonstrated here that thin films of vanadium oxide can be deposited at modest substrate temperatures by dc reactive sputtering from a vanadium target in an O2-Ar working gas using a planar magnetron source. Resistivity ratios of about 5000 are found between a semiconductor phase with a resistivity of about 5 Ohm cm and a metallic phase with a resistivity of about 0.001 Ohm cm for films deposited onto borosilicate glass substrates at about 400 C. X-ray diffraction shows the films to be single-phase VO2 with a monoclinic structure. The VO2 films are obtained for a narrow range of O2 injection rates which correspond to conditions where cathode poisoning is just starting to occur.

  10. Controlled formation of anatase and rutile TiO2 thin films by reactive magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Rafieian, Damon; Ogieglo, Wojciech; Savenije, Tom; Lammertink, Rob G. H.

    2015-09-01

    We discuss the formation of TiO2 thin films via DC reactive magnetron sputtering. The oxygen concentration during sputtering proved to be a crucial parameter with respect to the final film structure and properties. The initial deposition provided amorphous films that crystallise upon annealing to anatase or rutile, depending on the initial sputtering conditions. Substoichiometric films (TiOx<2), obtained by sputtering at relatively low oxygen concentration, formed rutile upon annealing in air, whereas stoichiometric films formed anatase. This route therefore presents a formation route for rutile films via lower (<500 °C) temperature pathways. The dynamics of the annealing process were followed by in situ ellipsometry, showing the optical properties transformation. The final crystal structures were identified by XRD. The anatase film obtained by this deposition method displayed high carriers mobility as measured by time-resolved microwave conductance. This also confirms the high photocatalytic activity of the anatase films.

  11. Hall mobility of cuprous oxide thin films deposited by reactive direct-current magnetron sputtering

    SciTech Connect

    Lee, Yun Seog; Winkler, Mark T.; Siah, Sin Cheng; Brandt, Riley; Buonassisi, Tonio

    2011-05-09

    Cuprous oxide (Cu{sub 2}O) is a promising earth-abundant semiconductor for photovoltaic applications. We report Hall mobilities of polycrystalline Cu{sub 2}O thin films deposited by reactive dc magnetron sputtering. High substrate growth temperature enhances film grain structure and Hall mobility. Temperature-dependent Hall mobilities measured on these films are comparable to monocrystalline Cu{sub 2}O at temperatures above 250 K, reaching 62 cm{sup 2}/V s at room temperature. At lower temperatures, the Hall mobility appears limited by carrier scattering from ionized centers. These observations indicate that sputtered Cu{sub 2}O films at high substrate growth temperature may be suitable for thin-film photovoltaic applications.

  12. Structural and thermal properties of nanocrystalline CuO synthesized by reactive magnetron sputtering

    SciTech Connect

    Verma, M.; Gupta, V. K.; Gautam, Y. K.; Dave, V.; Chandra, R.

    2014-01-28

    Recent research has shown immense application of metal oxides like CuO, MgO, CaO, Al{sub 2}O{sub 3}, etc. in different areas which includes chemical warfare agents, medical drugs, magnetic storage media and solar energy transformation. Among the metal oxides, CuO nanoparticles are of special interest because of their excellent gas sensing and catalytic properties. In this paper we report structural and thermal properties of CuO synthesized by reactive magnetron DC sputtering. The synthesized nanoparticles were characterized by X-ray diffractometer. The XRD result reveals that as DC power increased from 30W to 80W, size of the CuO nanoparticles increased. The same results have been verified through TEM analysis. Thermal properties of these particles were studied using thermogravimetry.

  13. Reactive DC magnetron sputtered zirconium nitride (ZrN) thin film and its characterization

    NASA Astrophysics Data System (ADS)

    Subramanian, B.; Ashok, K.; Sanjeeviraja, C.; Kuppusami, P.; Jayachandran, M.

    2008-05-01

    Zirconium nitride (ZrN) thin films were prepared by using reactive direct current (DC) magnetron sputtering onto different substrates. A good polycrystalline nature with face centered cubic structure was observed from X-ray Diffraction for ZrN thin films. The observed 'd' values from the X-ray Diffraction pattern were found to be in good agreement with the standard 'd' values (JCPDS-89-5269). An emission peak is observed at 587nm from Photoluminescence studies for the excitation at 430nm. The resistivity value (ρ) of 2.1798 (μΩ cm) was observed. ZrN has high wear resistance and low coefficient of friction. A less negative value of Ecorr and lower value of Icorr observed for ZrN / Mild Steel (MS) clearly confirm the better corrosion resistance than the bare substrate. Also the higher Rct value and lower Cdl value was observed for ZrN / MS from Nyquist - plot.

  14. Substrate Frequency Effects on Cr x N Coatings Deposited by DC Magnetron Sputtering

    NASA Astrophysics Data System (ADS)

    Obrosov, Aleksei; Naveed, Muhammad; Volinsky, Alex A.; Weiß, Sabine

    2017-01-01

    Controlled ion bombardment is a popular method to fabricate desirable coating structures and modify their properties. Substrate biasing at high frequencies is a possible technique, which allows higher ion density at the substrate compared with DC current bias. Moreover, high ion energy along with controlled adatom mobility would lead to improved coating growth. This paper focuses on a similar type of study, where effects of coating growth and properties of DC magnetron-sputtered chromium nitride (Cr x N) coatings at various substrate bias frequencies are discussed. Cr x N coatings were deposited by pulsed DC magnetron sputtering on Inconel 718 and (100) silicon substrates at 110, 160 and 280 kHz frequency at low duty cycle. Coating microstructure and morphology were studied by X-ray diffraction (XRD), atomic force microscopy (AFM), scanning electron microscopy (SEM), scratch adhesion testing and nanoindentation. Results indicate a transformation of columnar into glassy structure of Cr x N coatings with the substrate bias frequency increase. This transformation is attributed to preferential formation of the Cr2N phase at high frequencies compared with CrN at low frequencies. Increase in frequency leads to an increase in deposition rate, which is believed to be due to increase in plasma ion density and energy of the incident adatoms. An increase in coating hardness along with decrease in elastic modulus was observed at high frequencies. Scratch tests show a slight increase in coating adhesion, whereas no clear increase in coating roughness can be found with the substrate bias frequency.

  15. Substrate Frequency Effects on Cr x N Coatings Deposited by DC Magnetron Sputtering

    NASA Astrophysics Data System (ADS)

    Obrosov, Aleksei; Naveed, Muhammad; Volinsky, Alex A.; Weiß, Sabine

    2016-11-01

    Controlled ion bombardment is a popular method to fabricate desirable coating structures and modify their properties. Substrate biasing at high frequencies is a possible technique, which allows higher ion density at the substrate compared with DC current bias. Moreover, high ion energy along with controlled adatom mobility would lead to improved coating growth. This paper focuses on a similar type of study, where effects of coating growth and properties of DC magnetron-sputtered chromium nitride (Cr x N) coatings at various substrate bias frequencies are discussed. Cr x N coatings were deposited by pulsed DC magnetron sputtering on Inconel 718 and (100) silicon substrates at 110, 160 and 280 kHz frequency at low duty cycle. Coating microstructure and morphology were studied by X-ray diffraction (XRD), atomic force microscopy (AFM), scanning electron microscopy (SEM), scratch adhesion testing and nanoindentation. Results indicate a transformation of columnar into glassy structure of Cr x N coatings with the substrate bias frequency increase. This transformation is attributed to preferential formation of the Cr2N phase at high frequencies compared with CrN at low frequencies. Increase in frequency leads to an increase in deposition rate, which is believed to be due to increase in plasma ion density and energy of the incident adatoms. An increase in coating hardness along with decrease in elastic modulus was observed at high frequencies. Scratch tests show a slight increase in coating adhesion, whereas no clear increase in coating roughness can be found with the substrate bias frequency.

  16. Duty cycle control in reactive high-power impulse magnetron sputtering of hafnium and niobium

    NASA Astrophysics Data System (ADS)

    Ganesan, R.; Treverrow, B.; Murdoch, B.; Xie, D.; Ross, A. E.; Partridge, J. G.; Falconer, I. S.; McCulloch, D. G.; McKenzie, D. R.; Bilek, M. M. M.

    2016-06-01

    Instabilities in reactive sputtering have technological consequences and have been attributed to the formation of a compound layer on the target surface (‘poisoning’). Here we demonstrate how the duty cycle of high power impulse magnetron sputtering (HiPIMS) can be used to control the surface conditions of Hf and Nb targets. Variations in the time resolved target current characteristics as a function of duty cycle were attributed to gas rarefaction and to the degree of poisoning of the target surface. As the operation transitions from Ar driven sputtering to metal driven sputtering, the secondary electron emission changes and reduces the target current. The target surface transitions smoothly from a poisoned state at low duty cycles to a quasi-metallic state at high duty cycles. Appropriate selection of duty cycle increases the deposition rate, eliminates the need for active regulation of oxygen flow and enables stable reactive deposition of stoichiometric metal oxide films. A model is presented for the reactive HIPIMS process in which the target operates in a partially poisoned mode with different degrees of oxide layer distribution on its surface that depends on the duty cycle. Finally, we show that by tuning the pulse characteristics, the refractive indices of the metal oxides can be controlled without increasing the absorption coefficients, a result important for the fabrication of optical multilayer stacks.

  17. Synthesizing mixed phase titania nanocomposites with enhanced photoactivity and redshifted photoresponse by reactive DC magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Chen, Le

    Recent work points out the importance of the solid-solid interface in explaining the high photoactivity of mixed phase TiO2 catalysts. The goal of this research was to probe the synthesis-structure-function relationships of the solid-solid interfaces created by the reactive direct current (DC) magnetron sputtering of titanium dioxide. I hypothesize that the reactive DC magnetron sputtering is a useful method for synthesizing photo-catalysts with unique structure including solid-solid interfaces and surface defects that are associated with enhanced photoreactivity as well as a photoresponse shifted to longer wavelengths of light. I showed that sputter deposition provides excellent control of the phase and interface formation as well as the stoichiometry of the films. I explored the effects exerted by the process parameters of pressure, oxygen partial pressure, target power, substrate bias (RF), deposition incidence angle, and post annealing treatment on the structural and functional characteristics of the catalysts. I have successfully made pure and mixed phase TiO2 films. These films were characterized with UV-Vis, XPS, AFM, SEM, TEM, XRD and EPR, to determine optical properties, elemental stoichiometry, surface morphology, phase distribution and chemical coordination. Bundles of anatase-rutile nano-columns having high densities of dual-scale of interfaces among and within the columns are fabricated. Photocatalytic performance of the sputtered films as measured by the oxidation of the pollutant, acetaldehyde, and the reduction of CO2 for fuel (CH4) production was compared (normalized for surface area) to that of mixed phase TiO2 fabricated by other methods, including flame hydrolysis powders, and solgel deposited TiO 2 films. The sputtered mixed phase materials were far superior to the commercial standard (Degussa P25) and solgel TiO2 based on gas phase reaction of acetaldehyde oxidation under UV light and CO2 reduction under both UV and visible illuminations. The

  18. Antibacterial Cr-Cu-O films prepared by reactive magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Musil, J.; Blažek, J.; Fajfrlík, K.; Čerstvý, R.; Prokšová, Š.

    2013-07-01

    The paper reports on the effect of Cu content in the Cr-Cu-O film and its structure on its antibacterial activity and mechanical properties. The Cr-Cu-O films were prepared by reactive magnetron sputtering from composed Cr/Cu targets using a dual magnetron. The antibacterial activity of Cr-Cu-O films was tested on the killing of Escheria coli bacteria. Correlations between the structure of the Cr-Cu-O film, the content of Cu in the film and its (i) antibacterial efficiency and (ii) mechanical properties were investigated in detail. It was found that the 100% efficiency of the killing of E. coli bacteria on the surface of the Cr-Cu-O film is achieved if (1) the Cu content in the film is ≥15 at.% and (2) the film is either X-ray amorphous or crystalline with the CuCrO2 delafossite structure. These Cr-Cu-O films need no excitation and very effectively kill E. coli bacteria in the daylight as well as in the dark. The X-ray amorphous Cr-Cu-O films with ~20 at.% Cu exhibit a higher (i) hardness H ≈ 4 GPa, (ii) effective Young's modulus E* ≈ 72 GPa and (iii) elastic recovery We ≈ 37% compared with the crystalline Cr-Cu-O film with the CuCrO2 delafossite structure exhibiting H ≈ 1.2 GPa, E* ≈ 21 GPa and We ≈ 21%. Both films very effectively kill the E. coli bacteria, however, exhibit a low ratio H/E* < 0.1.

  19. Reactive magnetron sputtering deposition of bismuth tungstate onto titania nanoparticles for enhancing visible light photocatalytic activity

    NASA Astrophysics Data System (ADS)

    Ratova, Marina; Kelly, Peter J.; West, Glen T.; Tosheva, Lubomira; Edge, Michele

    2017-01-01

    Titanium dioxide - bismuth tungstate composite materials were prepared by pulsed DC reactive magnetron sputtering of bismuth and tungsten metallic targets in argon/oxygen atmosphere onto anatase and rutile titania nanoparticles. The use of an oscillating bowl placed beneath the two magnetrons arranged in a co-planar closed field configuration enabled the deposition of bismuth tungstate onto loose powders, rather than a solid substrate. The atomic ratio of the bismuth/tungsten coatings was controlled by varying the power applied to each target. The effect of the bismuth tungstate coatings on the phase, optical and photocatalytic properties of titania was investigated by X-ray diffraction, energy-dispersive X-ray spectroscopy (EDX), Brunauer-Emmett-Teller (BET) surface area measurements, transmission electron microscopy (TEM), UV-vis diffuse reflectance spectroscopy and an acetone degradation test. The latter involved measurements of the rate of CO2 evolution under visible light irradiation of the photocatalysts, which indicated that the deposition of bismuth tungstate resulted in a significant enhancement of visible light activity, for both anatase and rutile titania particles. The best results were achieved for coatings with a bismuth to tungsten atomic ratio of 2:1. In addition, the mechanism by which the photocatalytic activity of the TiO2 nanoparticles was enhanced by compounding it with bismuth tungstate was studied by microwave cavity perturbation. The results of these tests confirmed that such enhancement of the photocatalytic properties is due to more efficient photogenerated charge carrier separation, as well as to the contribution of the intrinsic photocatalytic properties of Bi2WO6.

  20. Formation of hydrogenated amorphous carbon films by reactive high power impulse magnetron sputtering containing C2H2 gas

    NASA Astrophysics Data System (ADS)

    Kimura, Takashi; Kamata, Hikaru

    2015-09-01

    Diamond-like carbon (DLC) films have attracted interest for material industries, because they have unique properties. Hydrogenated amorphous carbon films are prepared by reactive high power impulse magnetron sputtering (HiPIMS) containing C2H2 gas and the properties of the films produced in Ar/C2H2 and Ne/C2H2 HiPIMS are compared. Production of hydrocarbon radicals and their ions strongly depends on both electron temperature and electron density in HiPIMS. Therefore, the influence of the difference in buffer gas (Ar and Ne) on the film properties is also valuable to investigate. The film preparation is performed at an average power of 60 W and a repetition frequency of 110 Hz. Total pressure ranges between 0.3 and 2 Pa. The maximum of instantaneous power is about 20-25 kW, and the magnitude of the current is 35 A. A negative pulse voltage is applied to the substrates for about 15 μs after the target voltage changed from about -500 V to 0 V. Hardness of the films prepared by Ar/C2H2 HiPIMS monotonically decreases with increasing the total pressure, whereas that of the films prepared by Ne/C2H2 HiPIMS does not strongly depend on the total pressure. This work is partially supported by JSPS KAKENHI Grant Number 26420230.

  1. Optical and Chemical Properties of Mixed-valent Rhenium Oxide Films Synthesized by Reactive DC Magnetron Sputtering

    DTIC Science & Technology

    2015-04-03

    oxygen– argon environment. The oxygen and argon flow rates were systematically varied, while the extinction coefficient, k, of the deposited layers was...deposited using reactive magnetron sputtering employing a metallic rhenium target within an oxygen– argon environment. The oxygen and argon flow rates...throughout film growth, allows for the selection of oxygen (QO2) and argon (QAr) flow rates capable of increasing ReO3 content within the films

  2. Different properties of aluminum doped zinc oxide nanostructured thin films prepared by radio frequency magnetron sputtering

    SciTech Connect

    Bidmeshkipour, Samina Shahtahmasebi, Nasser

    2013-06-15

    Aluminium doped zinc oxide (AZO) nanostructured thin films are prepared by radio frequency magnetron sputtering on glass substrate using specifically designed ZnO target containing different amount of Al{sub 2}O{sub 3} powder as the Al doping source. The optical properties of the aluminium doped zinc oxide films are investigated. The topography of the deposited films were investigated by Atomic Force Microscopy. Variation of the refractive index by annealing temperature are considered and it is seen that the refractive index increases by increasing the annealing temperature.

  3. Electrical and optical properties of molybdenum doped zinc oxide films prepared by reactive RF magnetron sputtering

    SciTech Connect

    Reddy, R. Subba; Sreedhar, A.; Uthanna, S.

    2015-08-28

    Molybdenum doped zinc oxide (MZO) films were deposited on to glass substrates held at temperatures in the range from 303 to 673 K by reactive RF magnetron sputtering method. The chemical composition, crystallographic structure and surface morphology, electrical and optical properties of the films were determined. The films contained the molybdenum of 2.7 at. % in ZnO. The films deposited at 303 K were of X-ray amorphous. The films formed at 473 K were of nanocrystalline in nature with wurtzite structure. The crystallite size of the films was increased with the increase of substrate temperature. The optical transmittance of the films was in the visible range was 80–85%. The molybdenum (2.7 at %) doped zinc oxide films deposited at substrate temperature of 573 K were of nanocrystalline with electrical resistivity of 7.2×10{sup −3} Ωcm, optical transmittance of 85 %, optical band gap of 3.35 eV and figure of merit 30.6 Ω{sup −1}cm{sup −1}.

  4. Synthesis of copper nitride films doped with Fe, Co, or Ni by reactive magnetron sputtering

    SciTech Connect

    Yang, Jianbo; Huang, Saijia; Wang, Zhijiao; Hou, Yuxuan; Shi, Yuyu; Zhang, Jian; Yang, Jianping Li, Xing'ao

    2014-09-01

    Copper nitride (Cu{sub 3}N) and Fe-, Co-, and Ni-doped Cu{sub 3}N films were prepared by reactive magnetron sputtering. The films were deposited on silicon substrates at room temperature using pure Cu target and metal chips. The molar ratio of Cu to N atoms in the as-prepared Cu{sub 3}N film was 2.7:1, which is comparable with the stoichiometry ratio 3:1. X-ray diffraction measurements showed that the films were composed of Cu{sub 3}N crystallites with anti-ReO{sub 3} structure and adopted different preferred orientations. The reflectance of the four samples decreased in the wavelength range of 400–830 nm, but increased rapidly within wavelength range of 830–1200 nm. Compared with the Cu{sub 3}N films, the resistivity of the doped Cu{sub 3}N films decreased by three orders of magnitude. These changes have great application potential in optical and electrical devices based on Cu{sub 3}N films.

  5. Adhesion analysis for chromium nitride thin films deposited by reactive magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Rusu, F. M.; Merie, V. V.; Pintea, I. M.; Molea, A.

    2016-08-01

    The thin film industry is continuously growing due to the wide range of applications that require the fabrication of advanced components such as sensors, biological implants, micro-electromechanical devices, optical coatings and so on. The selection regarding the deposition materials, as well as the deposition technology influences the properties of the material and determines the suitability of devices for certain real-world applications. This paper is focused on the adhesion force for several chromium nitride thin films obtained by reactive magnetron sputtering. All chromium nitride thin films were deposited on a silicon substrate, the discharge current and the argon flow being kept constant. The main purpose of the paper is to determine the influence of deposition parameters on the adhesion force. Therefore some of the deposition parameters were varied in order to study their effect on the adhesion force. Experimentally, the values of the adhesion force were determined in multiple points for each sample using the spectroscopy in point mode of the atomic force microscope. The obtained values were used to estimate the surface energy of the CrN thin films based on two existing mathematical models for the adhesion force when considering the contact between two bodies.

  6. Structural, optical and electrical properties of WOxNy filmsdeposited by reactive dual magnetron sputtering

    SciTech Connect

    Mohamed, Sodky H.; Anders, Andre

    2006-06-05

    Thin films of tungsten oxynitride were prepared by dual magnetron sputtering of tungsten using argon/oxygen/nitrogen gas mixtures with various nitrogen/oxygen ratios. The presence of even small amounts of oxygen had a great effect not only on the composition but on the structure of WOxNy films, as shown by Rutherford backscattering and x-ray diffraction, respectively. Significant incorporation of nitrogen occurred only when the nitrogen partial pressure exceeded 89 percent of the total reactive gas pressure. Sharp changes in the stoichiometry, deposition rate, room temperature resistivity, electrical activation energy and optical band gap were observed when the nitrogen/oxygen ratio was high.The deposition rate increased from 0.31 to 0.89 nm/s, the room temperature resistivity decreased from 1.65 x 108 to 1.82 x 10-2 ?cm, the electrical activation energy decreased from 0.97 to 0.067 eV, and the optical band gap decreased from 3.19 to 2.94 eV upon nitrogen incorporation into the films. WOxNy films were highly transparent as long as the nitrogen incorporation was low, and were brownish (absorbing) and partially reflecting as nitrogen incorporation became significant.

  7. Nanocharacterization of titanium nitride thin films obtained by reactive magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Merie, V. V.; Pustan, M. S.; Bîrleanu, C.; Negrea, G.

    2014-08-01

    Titanium nitride thin films are used in applications such as tribological layers for cutting tools, coating of some medical devices (scalpel blades, prosthesis, implants etc.), sensors, electrodes for bioelectronics, microelectronics, diffusion barrier, bio-microelectromechanical systems (Bio-MEMS) and so on. This work is a comparative study concerning the influence of substrate temperature on some mechanical and tribological characteristics of titanium nitride thin films. The researched thin films were obtained by reactive magnetron sputtering method. The experiments employed two kinds of substrates: a steel substrate and a silicon one. The elaboration of titanium nitride thin films was done at two temperatures. First, the obtaining was realized when the substrates were at room temperature, and second, the obtaining was realized when the substrates were previously heated at 250 °C. The elaborated samples were then investigated by atomic force microscopy in order to establish their mechanical and tribological properties. The nanohardness, roughness, friction force are some of the determined characteristics. The results marked out that the substrate which was previously heated at 250 °C led to the obtaining of more adherent titanium nitride thin films than the substrate used at room temperature.

  8. Nanocharacterization of Titanium Nitride Thin Films Obtained by Reactive Magnetron Sputtering

    NASA Astrophysics Data System (ADS)

    Merie, Violeta Valentina; Pustan, Marius Sorin; Bîrleanu, Corina; Negrea, Gavril

    2015-05-01

    Titanium nitride thin films are used in applications such as tribological layers for cutting tools, coating of some medical devices (scalpel blades, prosthesis, implants, etc.), sensors, electrodes for bioelectronics, microelectronics, diffusion barrier, bio-micro-electromechanical systems, and so on. This work is a comparative study concerning the influence of substrate temperature on some mechanical and tribological characteristics of titanium nitride thin films. The researched thin films were obtained by the reactive magnetron sputtering method. The experiments employed two kinds of substrates: a steel substrate and a silicon one. The elaboration of titanium nitride thin films was done at two temperatures. First, when the substrates were at room temperature, and second, when the substrates were previously heated at 250°C. The temperature of 250°C was kept constant during the deposition of the films. The samples were then investigated by atomic force microscopy in order to establish their mechanical and tribological properties. The nanohardness, Young's modulus, roughness, and friction force were some of the determined characteristics. The results demonstrated that the substrate which was previously heated at 250°C led to the obtaining of more adherent titanium nitride thin films than the substrate used at room temperature. The preheating of both substrates determined the decrease of thin films roughness. The friction force, nanohardness and Young's modulus of the tested samples increased when the substrates were preheated at 250°C.

  9. Thermal stability of tungsten sub-nitride thin film prepared by reactive magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Zhang, X. X.; Wu, Y. Z.; Mu, B.; Qiao, L.; Li, W. X.; Li, J. J.; Wang, P.

    2017-03-01

    Tungsten sub-nitride thin films deposited on silicon samples by reactive magnetron sputtering were used as a model system to study the phase stability and microstructural evolution during thermal treatments. XRD, SEM&FIB, XPS, RBS and TDS were applied to investigate the stability of tungsten nitride films after heating up to 1473 K in vacuum. At the given experimental parameters a 920 nm thick crystalline film with a tungsten and nitrogen stoichiometry of 2:1 were achieved. The results showed that no phase and microstructure change occurred due to W2N film annealing in vacuum up to 973 K. Heating up to 1073 K led to a partial decomposition of the W2N phase and the formation of a W enrichment layer at the surface. Increasing the annealing time at the same temperature, the further decomposition of the W2N phase was negligible. The complete decomposition of W2N film happened as the temperature reached up to 1473 K.

  10. Structural and optical properties of DC reactive magnetron sputtered zinc aluminum oxide thin films

    SciTech Connect

    Kumar, B. Rajesh; Rao, T. Subba

    2014-10-15

    Highly transparent conductive Zinc Aluminum Oxide (ZAO) thin films have been deposited on glass substrates using DC reactive magnetron sputtering method. The thin films were deposited at 200 °C and post-deposition annealing from 15 to 90 min. XRD patterns of ZAO films exhibit only (0 0 2) diffraction peak, indicating that they have c-axis preferred orientation perpendicular to the substrate. Scanning electron microscopy (SEM) is used to study the surface morphology of the films. The grain size obtained from SEM images of ZAO thin films are found to be in the range of 20 - 26 nm. The minimum resistivity of 1.74 × 10{sup −4} Ω cm and an average transmittance of 92% are obtained for the thin film post annealed for 30 min. The optical band gap of ZAO thin films increased from 3.49 to 3.60 eV with the increase of annealing time due to Burstein-Moss effect. The optical constants refractive index (n) and extinction coefficient (k) were also determined from the optical transmission spectra.

  11. A Complementary Type of Electrochromic Device by Radio Frequency Magnetron Sputtering System

    NASA Astrophysics Data System (ADS)

    Oksuz, Lutfi; Kiristi, Melek; Bozduman, Ferhat; Uygun Oksuz, Aysegul

    2014-10-01

    Electrochromic (EC) devices can change their optical properties reversibly in the visible region (400-800 nm) upon charge insertion/extraction reactions according to the applied voltage. A complementary type of EC device composes of two electrochromic layers, which is separated by an ionic conduction layer (electrolyte). In this work, the EC device was fabricated using vanadium oxide (V2O5) and titanium doped tungsten oxide (WO3-TiO2) electrodes. The EC electrodes were deposited as thin film structures by a reactive RF magnetron sputtering system in a medium of gas mixture of argon and oxygen. surface morphology of the films was characterized by scanning electron microscopy (SEM) and atomic force microscopy (AFM). Electrochemical property and durability of the EC device was investigated by a potentiostat system. Optical measurement was examined under applied voltages of +/- 2.5 V by a computer-controlled system, constantly.

  12. Origin of stress in radio frequency magnetron sputtered zinc oxide thin films

    SciTech Connect

    Menon, Rashmi; Gupta, Vinay; Sreenivas, K.; Tan, H. H.; Jagadish, C.

    2011-03-15

    Highly c-axis oriented ZnO thin films have been deposited on silicon substrates by planar rf magnetron sputtering under varying pressure (10-50 mTorr) and oxygen percentage (50-100%) in the reactive gas (Ar + O{sub 2}) mixture. The as-grown films were found to be stressed over a wide range from -1 x 10{sup 11} to -2 x 10{sup 8} dyne/cm{sup 2} that in turn depends strongly on the processing conditions, and the film becomes stress free at a unique combination of sputtering pressure and reactive gas composition. Raman spectroscopy and photoluminescence (PL) analyses identified the origin of stress as lattice distortion due to defects introduced in the ZnO thin film. FTIR study reveals that Zn-O bond becomes stronger with the increase in oxygen fraction in the reactive gas mixture. The lattice distortion or stress depends on the type of defects introduced during deposition. PL spectra show the formation of a shoulder in band emission with an increase in the processing pressure and are related to the presence of stress. The ratio of band emission to defect emission decreases with the increase in oxygen percentage from 50 to 100%. The studies show a correlation of stress with the structural, vibrational, and photoluminescence properties of the ZnO thin film. The systematic study of the stress will help in the fabrication of efficient devices based on ZnO film.

  13. Studies on optoelectronic properties of DC reactive magnetron sputtered CdTe thin films

    SciTech Connect

    Kumar, B. Rajesh; Hymavathi, B.; Rao, T. Subba

    2014-01-28

    Cadmium telluride continues to be a leading candidate for the development of cost effective photovoltaics for terrestrial applications. In the present work two individual metallic targets of Cd and Te were used for the deposition of CdTe thin films on mica substrates from room temperature to 300 °C by DC reactive magnetron sputtering method. XRD patterns of CdTe thin films deposited on mica substrates exhibit peaks at 2θ = 27.7°, 46.1° and 54.6°, which corresponds to reflection on (1 1 1), (2 2 0) and (3 1 1) planes of CdTe cubic structure. The intensities of XRD patterns increases with the increase of substrate temperature upto 150 °C and then it decreases at higher substrate temperatures. The conductivity of CdTe thin films measured from four probe method increases with the increase of substrate temperature. The activation energies (ΔE) are found to be decrease with the increase of substrate temperature. The optical transmittance spectra of CdTe thin films deposited on mica have a clear interference pattern in the longer wavelength region. The films have good transparency (T > 85 %) exhibiting interference pattern in the spectral region between 1200 – 2500 nm. The optical band gap of CdTe thin films are found to be in the range of 1.48 – 1.57. The refractive index, n decreases with the increase of wavelength, λ. The value of n and k increases with the increase of substrate temperature.

  14. Properties of Cr2AlC MAX phase thin films prepared by reactive magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Buck, Zachary; Donato, Tyler; Rotella, Christopher; Lunk, Carl; Lofland, S. E.; Hettinger, J. D.

    2012-02-01

    Mn+ 1AXn (MAX) phases, where n is 1, 2, and 3, M is an early transition metal, A is an A-group element, and X is either C or N, are ternary carbides with unique properties such as low density, easy machinability, and good oxidation resistance. The MAX phase Cr2AlC is of particular interest for industrial applications to its excellent high-temperature oxidation resistance and relatively low synthesis temperature. We prepared Cr2AlC thin films on c-axis oriented single crystal Al2O3, glassy carbon and Si thermal oxide substrates using reactive magnetron sputtering as precursor materials for carbide-derived carbon (CDC) films for ``on-chip'' supercapacitors. Film deposition was optimized using elemental composition data obtained by WDXRF. Optimized films were characterized using XRD and scanning electron microscopy. It was found that textured Cr2AlC films only form when the composition was Al-rich allowing the formation of a Cr5Al8 interfacial layer. As film composition was optimized, the interfacial layer did not form but the XRD peaks associated with the Cr2AlC also decreased in magnitude. Extremely high-textured films were grown when a thin buffer layer of CrAl2 was deposited on the substrate before depositing the Cr2AlC films. This result suggests that Cr2AlC films may not be ideal for CDC applications since the films may ``lift-off'' during conversion due to the existence of the naturally occurring buffer-layer.

  15. Magnetic field strength influence on the reactive magnetron sputter deposition of Ta2O5

    NASA Astrophysics Data System (ADS)

    Hollerweger, R.; Holec, D.; Paulitsch, J.; Rachbauer, R.; Polcik, P.; Mayrhofer, P. H.

    2013-08-01

    Reactive magnetron sputtering enables the deposition of various thin films to be used for protective as well as optical and electronic applications. However, progressing target erosion during sputtering results in increased magnetic field strengths at the target surface. Consequently, the glow discharge, the target poisoning, and hence the morphology, crystal structure and stoichiometry of the prepared thin films are influenced. Therefore, these effects were investigated by varying the cathode current Im between 0.50 and 1.00 A, the magnetic field strength B between 45 and 90 mT, and the O2/(Ar + O2) flow rate ratio Γ between 0% and 100%. With increasing oxygen flow ratio a substoichiometric TaOx oxide forms at the metallic Ta target surface which further transfers to a non-conductive tantalum pentoxide Ta2O5, impeding a stable dc glow discharge. These two transition zones (from Ta to TaOx and from TaOx to Ta2O5) shift to higher oxygen flow rates for increasing target currents. In contrast, increasing the magnetic field strength (e.g., due to sputter erosion) mainly shifts the TaOx to Ta2O5 transition to lower oxygen flow rates while marginally influencing the Ta to TaOx transition. To allow for a stable dc glow discharge (and to suppress the formation of non-conductive Ta2O5 at the target) even at Γ = 100% either a high target current (Im ⩾ 1 A) or a low magnetic field strength (B ⩽ 60 mT) is necessary. These conditions are required to prepare stoichiometric and fully crystalline Ta2O5 films.

  16. Reactive sputter magnetron reactor for preparation of thin films and simultaneous in situ structural study by X-ray diffraction.

    PubMed

    Bürgi, J; Neuenschwander, R; Kellermann, G; García Molleja, J; Craievich, A F; Feugeas, J

    2013-01-01

    The purpose of the designed reactor is (i) to obtain polycrystalline and∕or amorphous thin films by controlled deposition induced by a reactive sputtering magnetron and (ii) to perform a parallel in situ structural study of the deposited thin films by X-ray diffraction, in real time, during the whole growth process. The designed reactor allows for the control and precise variation of the relevant processing parameters, namely, magnetron target-to-sample distance, dc magnetron voltage, and nature of the gas mixture, gas pressure and temperature of the substrate. On the other hand, the chamber can be used in different X-ray diffraction scanning modes, namely, θ-2θ scanning, fixed α-2θ scanning, and also low angle techniques such as grazing incidence small angle X-ray scattering and X-ray reflectivity. The chamber was mounted on a standard four-circle diffractometer located in a synchrotron beam line and first used for a preliminary X-ray diffraction analysis of AlN thin films during their growth on the surface of a (100) silicon wafer.

  17. Arsenic doped p-type zinc oxide films grown by radio frequency magnetron sputtering

    SciTech Connect

    Fan, J. C.; Zhu, C. Y.; Fung, S.; To, C. K.; Yang, B.; Beling, C. D.; Ling, C. C.; Zhong, Y. C.; Wong, K. S.; Xie, Z.; Brauer, G.; Skorupa, W.; Anwand, W.

    2009-10-01

    As-doped ZnO films were grown by the radio frequency magnetron sputtering method. As the substrate temperature during growth was raised above approx400 deg. C, the films changed from n type to p type. Hole concentration and mobility of approx6x10{sup 17} cm{sup -3} and approx6 cm{sup 2} V{sup -1} s{sup -1} were achieved. The ZnO films were studied by secondary ion mass spectroscopy, x-ray photoelectron spectroscopy (XPS), low temperature photoluminescence (PL), and positron annihilation spectroscopy (PAS). The results were consistent with the As{sub Zn}-2V{sub Zn} shallow acceptor model proposed by Limpijumnong et al. [Phys. Rev. Lett. 92, 155504 (2004)]. The results of the XPS, PL, PAS, and thermal studies lead us to suggest a comprehensive picture of the As-related shallow acceptor formation.

  18. Hydroxyapatite coatings on nanotubular titanium dioxide thin films prepared by radio frequency magnetron sputtering.

    PubMed

    Shin, Jinho; Lee, Kwangmin; Koh, Jeongtae; Son, Hyeju; Kim, Hyunseung; Lim, Hyun-Pil; Yun, Kwidug; Oh, Gyejeong; Lee, Seokwoo; Oh, Heekyun; Lee, Kyungku; Hwang, Gabwoon; Park, Sang-Won

    2013-08-01

    In this study, hydroxyapatite (HA) was coated on anodized titanium (Ti) surfaces through radio frequency magnetron sputtering in order to improve biological response of the titanium surface. All the samples were blasted with resorbable blasting media (RBM). RBM-blasted Ti surface, anodized Ti surface, as-sputtered HA coating on the anodized Ti surface, and heat-treated HA coating on the anodized Ti surface were prepared. The samples were characterized using scanning electron microscopy and X-ray photoemission spectroscopy, and biologic responses were evaluated. The top of the TiO2 nanotubes was not closed by HA particles when the coating time is less than 15 minutes. It was demonstrated that the heat-treated HA was well-crystallized and this enhanced the cell attachment of the anodized Ti surface.

  19. Cleaning of HT-7 Tokamak Exposed First Mirrors by Radio Frequency Magnetron Sputtering Plasma

    NASA Astrophysics Data System (ADS)

    Yan, Rong; Chen, Junling; Chen, Longwei; Ding, Rui; Zhu, Dahuan

    2014-12-01

    The stainless steel (SS) first mirror pre-exposed in the deposition-dominated environment of the HT-7 tokamak was cleaned in the newly built radio frequency (RF) magnetron sputtering plasma device. The deposition layer on the FM surface formed during the exposure was successfully removed by argon plasma with a RF power of about 80 W and a gas pressure of 0.087 Pa for 30 min. The total reflectivity of the mirrors was recovered up to 90% in the wavelength range of 300-800 nm, while the diffuse reflectivity showed a little increase, which was attributed to the increase of surface roughness in sputtering, and residual contaminants. The FMs made from single crystal materials could help to achieve a desired recovery of specular reflectivity in the future.

  20. Arsenic doped p-type zinc oxide films grown by radio frequency magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Fan, J. C.; Zhu, C. Y.; Fung, S.; Zhong, Y. C.; Wong, K. S.; Xie, Z.; Brauer, G.; Anwand, W.; Skorupa, W.; To, C. K.; Yang, B.; Beling, C. D.; Ling, C. C.

    2009-10-01

    As-doped ZnO films were grown by the radio frequency magnetron sputtering method. As the substrate temperature during growth was raised above ˜400 °C, the films changed from n type to p type. Hole concentration and mobility of ˜6×1017 cm-3 and ˜6 cm2 V-1 s-1 were achieved. The ZnO films were studied by secondary ion mass spectroscopy, x-ray photoelectron spectroscopy (XPS), low temperature photoluminescence (PL), and positron annihilation spectroscopy (PAS). The results were consistent with the AsZn-2VZn shallow acceptor model proposed by Limpijumnong et al. [Phys. Rev. Lett. 92, 155504 (2004)]. The results of the XPS, PL, PAS, and thermal studies lead us to suggest a comprehensive picture of the As-related shallow acceptor formation.

  1. Thermal conductivity of nitride films of Ti, Cr, and W deposited by reactive magnetron sputtering

    SciTech Connect

    Jagannadham, Kasichainula

    2015-05-15

    Nitride films of Ti, Cr, and W were deposited using reactive magnetron sputtering from metal targets in argon and nitrogen plasma. TiN films with (200) orientation were achieved on silicon (100) at the substrate temperature of 500 and 600 °C. The films were polycrystalline at lower temperature. An amorphous interface layer was observed between the TiN film and Si wafer deposited at 600 °C. TiN film deposited at 600 °C showed the nitrogen to Ti ratio to be near unity, but films deposited at lower temperature were nitrogen deficient. CrN film with (200) orientation and good stoichiometry was achieved at 600 °C on Si(111) wafer but the film deposited at 500 °C showed cubic CrN and hexagonal Cr{sub 2}N phases with smaller grain size and amorphous back ground in the x-ray diffraction pattern. An amorphous interface layer was not observed in the cubic CrN film on Si(111) deposited at 600 °C. Nitride film of tungsten deposited at 600 °C on Si(100) wafer was nitrogen deficient, contained both cubic W{sub 2}N and hexagonal WN phases with smaller grain size. Nitride films of tungsten deposited at 500 °C were nonstoichiometric and contained cubic W{sub 2}N and unreacted W phases. There was no amorphous phase formed along the interface for the tungsten nitride film deposited at 600 °C on the Si wafer. Thermal conductivity and interface thermal conductance of all the nitride films of Ti, Cr, and W were determined by transient thermoreflectance technique. The thermal conductivity of the films as function of deposition temperature, microstructure, nitrogen stoichiometry and amorphous interaction layer at the interface was determined. Tungsten nitride film containing both cubic and hexagonal phases was found to exhibit much higher thermal conductivity and interface thermal conductance. The amorphous interface layer was found to reduce effective thermal conductivity of TiN and CrN films.

  2. Physical properties of epitaxial ZrN/MgO(001) layers grown by reactive magnetron sputtering

    SciTech Connect

    Mei, A. B.; Zhang, C.; Sardela, M.; Eckstein, J. N.; Rockett, A.; Howe, B. M.; Hultman, L.; Petrov, I.; Greene, J. E.

    2013-11-15

    Single-crystal ZrN films, 830 nm thick, are grown on MgO(001) at 450 °C by magnetically unbalanced reactive magnetron sputtering. The combination of high-resolution x-ray diffraction reciprocal lattice maps, high-resolution cross-sectional transmission electron microscopy, and selected-area electron diffraction shows that ZrN grows epitaxially on MgO(001) with a cube-on-cube orientational relationship, (001){sub ZrN}‖(001){sub MgO} and [100]{sub ZrN}‖[100]{sub MgO}. The layers are essentially fully relaxed with a lattice parameter of 0.4575 nm, in good agreement with reported results for bulk ZrN crystals. X-ray reflectivity results reveal that the films are completely dense with smooth surfaces (roughness = 1.3 nm, consistent with atomic-force microscopy analyses). Based on temperature-dependent electronic transport measurements, epitaxial ZrN/MgO(001) layers have a room-temperature resistivity ρ{sub 300K} of 12.0 μΩ-cm, a temperature coefficient of resistivity between 100 and 300 K of 5.6 × 10{sup −8}Ω-cm K{sup −1}, a residual resistivity ρ{sub o} below 30 K of 0.78 μΩ-cm (corresponding to a residual resistivity ratio ρ{sub 300Κ}/ρ{sub 15K} = 15), and the layers exhibit a superconducting transition temperature of 10.4 K. The relatively high residual resistivity ratio, combined with long in-plane and out-of-plane x-ray coherence lengths, ξ{sub ‖} = 18 nm and ξ{sub ⊥} = 161 nm, indicates high crystalline quality with low mosaicity. The reflectance of ZrN(001), as determined by variable-angle spectroscopic ellipsometry, decreases slowly from 95% at 1 eV to 90% at 2 eV with a reflectance edge at 3.04 eV. Interband transitions dominate the dielectric response above 2 eV. The ZrN(001) nanoindentation hardness and modulus are 22.7 ± 1.7 and 450 ± 25 GPa.

  3. Decorative black TiCxOy film fabricated by DC magnetron sputtering without importing oxygen reactive gas

    NASA Astrophysics Data System (ADS)

    Ono, Katsushi; Wakabayashi, Masao; Tsukakoshi, Yukio; Abe, Yoshiyuki

    2016-02-01

    Decorative black TiCxOy films were fabricated by dc (direct current) magnetron sputtering without importing the oxygen reactive gas into the sputtering chamber. Using a ceramic target of titanium oxycarbide (TiC1.59O0.31), the oxygen content in the films could be easily controlled by adjustment of total sputtering gas pressure without remarkable change of the carbon content. The films deposited at 2.0 and 4.0 Pa, those are higher pressure when compared with that in conventional magnetron sputtering, showed an attractive black color. In particular, the film at 4.0 Pa had the composition of TiC1.03O1.10, exhibited the L* of 41.5, a* of 0.2 and b* of 0.6 in CIELAB color space. These values were smaller than those in the TiC0.29O1.38 films (L* of 45.8, a* of 1.2 and b* of 1.2) fabricated by conventional reactive sputtering method from the same target under the conditions of gas pressure of 0.3 Pa and optimized oxygen reactive gas concentration of 2.5 vol.% in sputtering gas. Analysis of XRD and XPS revealed that the black film deposited at 4.0 Pa was the amorphous film composed of TiC, TiO and C. The adhesion property and the heat resisting property were enough for decorative uses. This sputtering process has an industrial advantage that the decorative black coating with color uniformity in large area can be easily obtained by plain operation because of unnecessary of the oxygen reactive gas importing which is difficult to be controlled uniformly in the sputtering chamber.

  4. BiVO4 photoanodes for water splitting with high injection efficiency, deposited by reactive magnetron co-sputtering

    NASA Astrophysics Data System (ADS)

    Gong, Haibo; Freudenberg, Norman; Nie, Man; van de Krol, Roel; Ellmer, Klaus

    2016-04-01

    Photoactive bismuth vanadate (BiVO4) thin films were deposited by reactive co-magnetron sputtering from metallic Bi and V targets. The effects of the V-to-Bi ratio, molybdenum doping and post-annealing on the crystallographic and photoelectrochemical (PEC) properties of the BiVO4 films were investigated. Phase-pure monoclinic BiVO4 films, which are more photoactive than the tetragonal BiVO4 phase, were obtained under slightly vanadium-rich conditions. After annealing of the Mo-doped BiVO4 films, the photocurrent increased 2.6 times compared to undoped films. After optimization of the BiVO4 film thickness, the photocurrent densities (without a catalyst or a blocking layer or a hole scavenger) exceeded 1.2 mA/cm2 at a potential of 1.23 VRHE under solar AM1.5 irradiation. The surprisingly high injection efficiency of holes into the electrolyte is attributed to the highly porous film morphology. This co-magnetron sputtering preparation route for photoactive BiVO4 films opens new possibilities for the fabrication of large-scale devices for water splitting.

  5. Influence of nitrogen admixture to argon on the ion energy distribution in reactive high power pulsed magnetron sputtering of chromium

    NASA Astrophysics Data System (ADS)

    Breilmann, W.; Maszl, C.; Hecimovic, A.; von Keudell, A.

    2017-04-01

    Reactive high power impulse magnetron sputtering (HiPIMS) of metals is of paramount importance for the deposition of various oxides, nitrides and carbides. The addition of a reactive gas such as nitrogen to an argon HiPIMS plasma with a metal target allows the formation of the corresponding metal nitride on the substrate. The addition of a reactive gas introduces new dynamics into the plasma process, such as hysteresis, target poisoning and the rarefaction of two different plasma gases. We investigate the dynamics for the deposition of chromium nitride by a reactive HiPIMS plasma using energy- and time-resolved ion mass spectrometry, fast camera measurements and temporal and spatially resolved optical emission spectroscopy. It is shown that the addition of nitrogen to the argon plasma gas significantly changes the appearance of the localized ionization zones, the so-called spokes, in HiPIMS plasmas. In addition, a very strong modulation of the metal ion flux within each HiPIMS pulse is observed, with the metal ion flux being strongly suppressed and the nitrogen molecular ion flux being strongly enhanced in the high current phase of the pulse. This behavior is explained by a stronger return effect of the sputtered metal ions in the dense plasma above the racetrack. This is best observed in a pure nitrogen plasma, because the ionization zones are mostly confined, implying a very high local plasma density and consequently also an efficient scattering process.

  6. Properties of a-C:H:Si thin films deposited by middle-frequency magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Jiang, Jinlong; Wang, Yubao; Du, Jinfang; Yang, Hua; Hao, Junying

    2016-08-01

    The silicon doped hydrogenated amorphous carbon (a-C:H:Si) films were prepared on silicon substrates by middle-frequency magnetron sputtering silicon target in an argon and methane gas mixture atmosphere. The deposition rate, chemical composition, structure, surface properties, stress, hardness and tribological properties in the ambient air of the films were systemically investigated using X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM), atomic force microscopy (AFM), nanoindentation and tribological tester. The results show that doped silicon content in the films is controlled in the wide range from 39.7 at.% to 0.2 at.% by various methane gas flow rate, and methane flow rate affects not only the silicon content but also its chemical bonding structure in the films due to the transformation of sputtering modes. Meanwhile, the sp3 carbon component in the films linearly increases with increasing of methane flow rate. The film deposited at moderate methane flow rate of 40-60 sccm exhibits the very smooth surface (RMS roughness 0.4 nm), low stress (0.42 GPa), high hardness (21.1 GPa), as well as low friction coefficient (0.038) and wear rate (1.6 × 10-7 mm3/Nm). The superior tribological performance of the films could be attributed to the formation and integral covering of the transfer materials on the sliding surface and their high hardness.

  7. Morphology of TiN thin films grown on MgO(001) by reactive dc magnetron sputtering

    SciTech Connect

    Ingason, A. S.; Magnus, F.; Olafsson, S.; Gudmundsson, J. T.

    2010-07-15

    Thin TiN films were grown by reactive dc magnetron sputtering on single-crystalline MgO(001) substrates at a range of temperatures from room temperature to 600 deg. C. Structural characterization was carried out using x-ray diffraction and reflection methods. TiN films grow epitaxially on the MgO substrates at growth temperatures of 200 deg. C and above. The crystal coherence length determined from Laue oscillations and the Scherrer method agrees with x-ray reflection thickness measurements to 6% and within 3% for growth temperatures of 200 and 600 deg. C, respectively. For lower growth temperatures the films are polycrystalline but highly textured and porous.

  8. Bimodal substrate biasing to control γ-Al{sub 2}O{sub 3} deposition during reactive magnetron sputtering

    SciTech Connect

    Prenzel, Marina; Kortmann, Annika; Stein, Adrian; Keudell, Achim von; Nahif, Farwah; Schneider, Jochen M.

    2013-09-21

    Al{sub 2}O{sub 3} thin films have been deposited at substrate temperatures between 500 °C and 600 °C by reactive magnetron sputtering using an additional arbitrary substrate bias to tailor the energy distribution of the incident ions. The films were characterized by X-ray diffraction and Fourier transform infrared spectroscopy. The film structure being amorphous, nanocrystalline, or crystalline was correlated with characteristic ion energy distributions. The evolving crystalline structure is connected with different levels of displacements per atom (dpa) in the growing film as being derived from TRIM simulations. The boundary between the formation of crystalline films and amorphous or nanocrystalline films was at 0.8 dpa for a substrate temperature of 500 °C. This threshold shifts to 0.6 dpa for films grown at 550 °C.

  9. An ionization region model of the reactive Ar/O2 high power impulse magnetron sputtering discharge

    NASA Astrophysics Data System (ADS)

    Gudmundsson, Jon Tomas; Lundin, Daniel; Brenning, Nils; Raadu, Michel A.; Huo, Chunqing; Minea, Tiberiu

    2016-09-01

    A reactive ionization region model (R-IRM) is developed to describe the reactive Ar/O2 high power impulse magnetron sputtering (HiPIMS) discharge with titanium target. We compare the discharge properties when the discharge is operated in the two well established operating modes, the metal mode and the poisoned mode. Experimentally, it is found that in the metal mode the discharge current waveform displays a typical non-reactive evolution, while in the poisoned mode the discharge current waveform becomes distinctly triangular and the current increases significantly. Using the R-IRM we find that when the discharge is operated in the metal mode Ar+ and Ti+-ions contribute most significantly (roughly equal amounts) to the discharge current while in the poisoned mode the Ar+-ions contribute most significantly to the discharge current while the contribution of O+-ions and secondary electron emission is much smaller. Furthermore, we find that recycling of ionized atoms coming from the target are required for the current generation in both modes of operation. In the metal mode self-sputter recycling dominates and in the poisoned mode working gas recycling dominates, and it is concluded that the dominating type of recycling determines the discharge current waveform.

  10. Characterization and in vitro evaluation of biphasic calcium pyrophosphate-tricalciumphosphate radio frequency magnetron sputter coatings.

    PubMed

    Takahashi, K; van den Beucken, J J J P; Wolke, J G C; Hayakawa, T; Nishiyama, N; Jansen, J A

    2008-03-01

    The objective of this study was to characterize the physicochemical, dissolution, and osteogenic properties of radio frequency magnetron sputtered dicalcium pyrophosphate/tricalciumphosphate (Pyro/TCP) and hydroxylapatite (HA) coatings. Therefore Pyro/TCP and HA coatings were deposited on grit-blasted titanium discs. The results showed that the deposited coatings were amorphous and changed into a crystalline structure after IR heat-treatment of 550 degrees C for HA and 650 degrees C for Pyro/TCP. Heat-treated HA coatings appeared to be stable during immersion in simulated body fluid (SBF), that is no changes in the XRD pattern were observed. Also, no dissolution of the coating was observed by scanning electron microscopy (SEM). Energy dispersive spectroscopy (EDS) revealed that the Ca/P ratio of the HA coatings remained constant during SBF immersion. On the other hand, the heat-treated Pyro/TCP coatings showed a surface reaction of calcium pyrophosphate into a beta-tricalcium phosphate phase during SBF immersion. This was confirmed by EDS analysis. Rat bone marrow-derived osteoblast-like cells cultured on the heat-treated substrates showed that cell proliferation and differentiation occurred on both types of bioceramic coatings. No significant differences for proliferation and early differentiation were observed between cells cultured on heat-treated Pyro/TCP and HA at individual time points. However, osteocalcin expression, a late marker for osteoblast-like cell differentiation, was significantly increased after 12 days of culture on HA-coatings. These results were confirmed by SEM observations and suggest increased osteogenic properties for HA-coatings over Pyro/TCP-coatings. Additional research is necessary to obtain conclusive evidence on the in vivo osteogenic capacity of Pyro/TCP coatings.

  11. Comparison of Y2O3:Bi3+ phosphor thin films fabricated by the spin coating and radio frequency magnetron techniques

    NASA Astrophysics Data System (ADS)

    Jafer, R. M.; Yousif, A.; Kumar, Vinod; Pathak, Trilok Kumar; Purohit, L. P.; Swart, H. C.; Coetsee, E.

    2016-09-01

    The reactive radio-frequency (RF) magnetron sputtering and spin coating fabrication techniques were used to fabricate Y2-xO3:Bix=0.5% phosphor thin films. The two techniques were analysed and compared as part of investigations being done on the application of down-conversion materials for a Si solar cell. The morphology, structural and optical properties of these thin films were investigated. The X-ray diffraction results of the thin films fabricated by both techniques showed cubic structures with different space groups. The optical properties showed different results because the Bi3+ ion is very sensitive towards its environment. The luminescence results for the thin film fabricated by the spin coating technique is very similar to the luminescence observed in the powder form. It showed three obvious emission bands in the blue and green regions centered at about 360, 410 and 495 nm. These emissions were related to the 3P1-1S0 transition of the Bi3+ ion situated in the two different sites of the Y2O3 matrix with I a-3(206) space group. Whereas the thin film fabricated by the radio frequency magnetron technique showed a broad single emission band in the blue region centered at about 416 nm. This was assigned to the 3P1-1S0 transition of the Bi3+ ion situated in one of the Y2O3 matrix's sites with a Fm-3 (225) space group. The spin coating fabrication technique is suggested to be the best technique to fabricate the Y2O3:Bi3+ phosphor thin films.

  12. An ionization region model of the reactive Ar/O2 high power impulse magnetron sputtering discharge

    NASA Astrophysics Data System (ADS)

    Gudmundsson, J. T.; Lundin, D.; Brenning, N.; Raadu, M. A.; Huo, Chunqing; Minea, T. M.

    2016-12-01

    A new reactive ionization region model (R-IRM) is developed to describe the reactive Ar/O2 high power impulse magnetron sputtering (HiPIMS) discharge with a titanium target. It is then applied to study the temporal behavior of the discharge plasma parameters such as electron density, the neutral and ion composition, the ionization fraction of the sputtered vapor, the oxygen dissociation fraction, and the composition of the discharge current. We study and compare the discharge properties when the discharge is operated in the two well established operating modes, the metal mode and the poisoned mode. Experimentally, it is found that in the metal mode the discharge current waveform displays a typical non-reactive evolution, while in the poisoned mode the discharge current waveform becomes distinctly triangular and the current increases significantly. Using the R-IRM we explore the current increase and find that when the discharge is operated in the metal mode Ar+ and Ti+ -ions contribute most significantly (roughly equal amounts) to the discharge current while in the poisoned mode the Ar+ -ions contribute most significantly to the discharge current and the contribution of O+ -ions, Ti+ -ions, and secondary electron emission is much smaller. Furthermore, we find that recycling of atoms coming from the target, that are subsequently ionized, is required for the current generation in both modes of operation. From the R-IRM results it is found that in the metal mode self-sputter recycling dominates and in the poisoned mode working gas recycling dominates. We also show that working gas recycling can lead to very high discharge currents but never to a runaway. It is concluded that the dominating type of recycling determines the discharge current waveform.

  13. Characterization of thin MoO3 films formed by RF and DC-magnetron reactive sputtering for gas sensor applications

    NASA Astrophysics Data System (ADS)

    Yordanov, R.; Boyadjiev, S.; Georgieva, V.; Vergov, L.

    2014-05-01

    The present work discusses a technology for deposition and characterization of thin molybdenum oxide (MoOx, MoO3) films studied for gas sensor applications. The samples were produced by reactive radio-frequency (RF) and direct current (DC) magnetron sputtering. The composition and microstructure of the films were studied by XPS, XRD and Raman spectroscopy, the morphology, using high resolution SEM. The research was focused on the sensing properties of the sputtered thin MoO3 films. Highly sensitive gas sensors were implemented by depositing films of various thicknesses on quartz resonators. Making use of the quartz crystal microbalance (QCM) method, these sensors were capable of detecting changes in the molecular range. Prototype QCM structures with thin MoO3 films were tested for sensitivity to NH3 and NO2. Even in as-deposited state and without heating the substrates, these films showed good sensitivity. Moreover, no additional thermal treatment is necessary, which makes the production of such QCM gas sensors simple and cost-effective, as it is fully compatible with the technology for producing the initial resonator. The films are sensitive at room temperature and can register concentrations as low as 50 ppm. The sorption is fully reversible, the films are stable and capable of long-term measurements.

  14. Influence of the composition of BCN films deposited by reactive magnetron sputtering on their properties.

    PubMed

    Martínez, C; Kyrsta, S; Cremer, R; Neuschütz, D

    2002-10-01

    Compounds of the B--C--N system are very promising to produce superhard coatings with good tribological, chemical, and thermal properties. To investigate the influence of the composition of BCN films on their properties, films with five different compositions at nearly constant nitrogen content were deposited on silicon wafers by magnetron sputtering from hexagonal boron nitride and graphite targets operated in RF and DC mode, respectively. The compositions and binding states of the films were determined by XPS. The nitrogen content was found to be almost constant for all films at about a 40 at-%, whereas boron and carbon compositions ranged between 15-35 and 25-50 at-%, respectively. The electronic and bonding structure of the coatings were analyzed by REELS using three different electron beam energies to obtain information at different depths. An increase of the carbon content of the films resulted in a significant shift of the pi-pi* interband transition with respect to the energy loss corresponding to h-BN. The absence of the pi-pi* transition in the energy loss spectra acquired at a beam energy of 1900 eV indicates the existence of a very thin overlayer mostly sp(2) bonded and probably with a distorted hexagonal structure. The position of the bulk plasmon losses corresponded to the hexagonal phase for the overlayer and presented a shift of more than 1.5 eV to the higher energy loss direction for the spectra obtained at 1900 eV beam energy. This shift and the absence of the sp(2)-bond fingerprint induced the possibility of an underlying disordered structure with a majority of sp(3) bonds.

  15. Process monitoring during AlN{sub x}O{sub y} deposition by reactive magnetron sputtering and correlation with the film's properties

    SciTech Connect

    Borges, Joel Vaz, Filipe; Marques, Luis; Martin, Nicolas

    2014-03-15

    In this work, AlN{sub x}O{sub y} thin films were deposited by reactive magnetron sputtering, using an aluminum target and an Ar/(N{sub 2}+O{sub 2}) atmosphere. The direct current magnetron discharge parameters during the deposition process were investigated by optical emission spectroscopy and a plasma floating probe was used. The discharge voltage, the electron temperature, the ion flux, and the optical emission lines were recorded for different reactive gas flows, near the target and close to the substrate. This information was correlated with the structural features of the deposits as a first step in the development of a system to control the structure and properties of the films during reactive magnetron sputtering. As the target becomes poisoned, the discharge voltage suffers an important variation, due to the modification of the secondary electron emission coefficient of the target, which is also supported by the evolution of the electron temperature and ion flux to the target. The sputtering yield of the target was also affected, leading to a reduction of the amount of Al atoms arriving to the substrate, according to optical emission spectroscopy results for Al emission line intensity. This behavior, together with the increase of nonmetallic elements in the films, allowed obtaining different microstructures, over a wide range of compositions, which induced different electrical and optical responses of films.

  16. Effects of Ti addiction in WO 3 thin film ammonia gas sensor prepared by dc reactive magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Hu, Ming; Yong, Cholyun; Feng, Youcai; Lv, Yuqiang; Han, Lei; Liang, Jiran; Wang, Haopeng

    2006-11-01

    WO 3 sensing films (1500 Å) were deposited using dc reactive magnetron sputtering method on alumina substrate on which patterned interdigital Pt electrodes were previously formed. The additive Ti was sputtered with different thickness (100-500 Å) onto WO 3 thin films and then the films as-deposited were annealed at 400°C in air for 3h. The crystal structure and chemical composition of the films were characterized by XRD and XPS analysis. The effect of Ti addition on sensitive properties of WO 3 thin film to the NH 3 gas was then discussed. WO 3 thin films added Ti revealed excellent sensitivity and response characteristics in the presence of low concentration of NH 3 (5-400 ppm) gas in air at 200°C operating temperature. Especially,in case 300 Å thickness of additive Ti, WO 3 thin films have a promotional effect on the response speed to NH 3 and selectivity enhanced with respect to other gases (CO, C IIH 5OH, CH 4). The influence of different substrates, including alumina, silicon and glass, on sensitivity to NH 3 gas has also been investigated.

  17. Structure and mechanical properties of Ti-Si-N films deposited by combined DC/RF reactive unbalanced magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Ding, X. Z.; Zeng, X. T.; Liu, Y. C.; Yang, Q.; Zhao, L. R.

    2004-11-01

    Ti-Si-N nanocomposite films with Si content between 0 and 13.5 at. % were deposited by combined DC/RF reactive unbalanced magnetron sputtering. The composition, structure, and mechanical properties of the as-deposited Ti-Si-N films were measured by energy dispersive analysis of x rays, x-ray diffraction (XRD), and nanoindentation experiments, respectively. All of the Ti-Si-N films exhibited a higher hardness than pure TiN films deposited under similar conditions. The highest hardness (~41 GPa) was obtained in the film with Si content of about 8 at. %. Ti-Si-N films also exhibited a higher resistance to plastic deformation (i.e., higher ratio H3/E*2) than pure TiN. XRD patterns revealed that the as-deposited films were composed of cubic TiN crystallites with a preferential orientation of (111). With increase of RF power applied to the Si targets, the TiN (111) peak intensity or TiN crystallite size increased in the lower RF power range but decreased in the higher RF power range, showing a maximum at an RF power of 500 W (power density ~1.14 W/cm2), corresponding to a Si content of about 5 at. % in the film.

  18. The effect of alumina and aluminium nitride coating by reactive magnetron sputtering on the resin bond strength to zirconia core

    PubMed Central

    Külünk, Şafak; Baba, Seniha; Öztürk, Özgür; Danişman, Şengül; Savaş, Soner

    2013-01-01

    PURPOSE Although several surface treatments have been recently investigated both under in vitro and in vivo conditions, controversy still exists regarding the selection of the most appropriate zirconia surface pre-treatment. The purpose of this study was to evaluate the effect of alumina (Al) and aluminium nitride (AlN) coating on the shear bond strength of adhesive resin cement to zirconia core. MATERIALS AND METHODS Fifty zirconia core discs were divided into 5 groups; air particle abrasion with 50 µm aluminum oxide particles (Al2O3), polishing + Al coating, polishing + AlN coating, air particle abrasion with 50 µm Al2O3 + Al coating and air particle abrasion with 50 µm Al2O3 + AlN coating. Composite resin discs were cemented to each of specimens. Shear bond strength (MPa) was measured using a universal testing machine. The effects of the surface preparations on each specimen were examined with scanning electron microscope (SEM). Data were statistically analyzed by one-way ANOVA (α=.05). RESULTS The highest bond strengths were obtained by air abrasion with 50 µm Al2O3, the lowest bond strengths were obtained in polishing + Al coating group (P<.05). CONCLUSION Al and AlN coatings using the reactive magnetron sputtering technique were found to be ineffective to increase the bond strength of adhesive resin cement to zirconia core. PMID:24353874

  19. Role of nitrogen in the formation of hard and elastic CNx thin films by reactive magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Hellgren, Niklas; Johansson, Mats P.; Broitman, Esteban; Hultman, Lars; Sundgren, Jan-Eric

    1999-02-01

    Carbon nitride films, deposited by reactive dc magnetron sputtering in Ar/N2 discharges, were studied with respect to composition, structure, and mechanical properties. CNx films, with 0<=x<=0.35, were grown onto Si (001) substrates at temperatures between 100 and 550 °C. The total pressure was kept constant at 3.0 mTorr with the N2 fraction varied from 0 to 1. As-deposited films were studied by Rutherford-backscattering spectroscopy, x-ray photoelectron spectroscopy, electron-energy loss spectroscopy, Raman and Fourier transform infrared spectroscopy, and nanoindentation. Three characteristic film structures could be identified: For temperatures below ~150 °C, an amorphous phase forms, the properties of which are essentially unaffected by the nitrogen concentration. For temperatures above ~200 °C, a transition from a graphitelike phase to a ``fullerenelike'' phase is observed when the nitrogen concentration increases from ~5 to ~15 at. %. This fullerenelike phase exhibits high hardness values and extreme elasticity, as measured by nanoindentation. A ``defected-graphite'' model, where nitrogen atoms goes into substitutional graphite sites, is suggested for explaining this structural transformation. When a sufficient number of nitrogen atoms is incorporated, formation of pentagons is promoted, leading to curving of the basal planes. This facilitates cross-linking between the planes and a distortion of the graphitic structure, and a strong three-dimensional covalently bonded network is formed.

  20. Ion beam analysis, corrosion resistance and nanomechanical properties of TiAlCN/CNx multilayer grown by reactive magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Alemón, B.; Flores, M.; Canto, C.; Andrade, E.; de Lucio, O. G.; Rocha, M. F.; Broitman, E.

    2014-07-01

    A novel TiAlCN/CNx multilayer coating, consisting of nine TiAlCN/CNx periods with a top layer 0.5 μm of CNx, was designed to enhance the corrosion resistance of CoCrMo biomedical alloy. The multilayers were deposited by dc and RF reactive magnetron sputtering from Ti0.5Al0.5 and C targets respectively in a N2/Ar plasma. The corrosion resistance and mechanical properties of the multilayer coatings were analyzed and compared to CoCrMo bulk alloy. Ion beam analysis (IBA) and X-ray diffraction tests were used to measure the element composition profiles and crystalline structure of the films. Corrosion resistance was evaluated by means of potentiodynamic polarization measurements using simulated body fluid (SBF) at typical body temperature and the nanomechanical properties of the multilayer evaluated by nanoindentation tests were analyzed and compared to CoCrMo bulk alloy. It was found that the multilayer hardness and the elastic recovery are higher than the substrate of CoCrMo. Furthermore the coated substrate shows a better general corrosion resistance than that of the CoCrMo alloy alone with no observation of pitting corrosion.

  1. Electrical and optical properties of CNx(0<=x<=0.25) films deposited by reactive magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Broitman, E.; Hellgren, N.; Järrendahl, K.; Johansson, M. P.; Olafsson, S.; Radnóczi, G.; Sundgren, J.-E.; Hultman, L.

    2001-01-01

    The electrical and optical properties of carbon-nitride CNx films (0⩽x⩽0.25) deposited by unbalanced reactive magnetron sputtering from a graphite target in mixed Ar/N2 discharges at a substrate temperature of 350 °C have been investigated. Pure C films exhibit a dark conductivity at room temperature of 25 Ω-1 cm-1, which grows up to 250 Ω-1 cm-1 for CNx films with N content of 20%. For CNx films, temperature-dependent conductivity measurements suggest that two electron conduction processes exist in the investigated temperature range 130

  2. AlN thin films deposited by DC reactive magnetron sputtering: effect of oxygen on film growth

    NASA Astrophysics Data System (ADS)

    García Molleja, Javier; José Gómez, Bernardo; Ferrón, Julio; Gautron, Eric; Bürgi, Juan; Abdallah, Bassam; Abdou Djouadi, Mohamed; Feugeas, Jorge; Jouan, Pierre-Yves

    2013-11-01

    Aluminum nitride is a ceramic compound with many technological applications in many fields, for example optics, electronics and resonators. Contaminants play a crucial role in the AlN performance. This paper focuses mainly in the effect of oxygen when AlN, with O impurities in its structure, is grown on oxidized layers. In this study, AlN thin films have been deposited at room temperature and low residual vacuum on SiO2/Si (1 0 0) substrates. AlN films were grown by DC reactive magnetron sputtering (aluminum target) and atmosphere composed by an argon/nitrogen mixture. Working pressure was 3 mTorr. Film characterization was performed by AES, XRD, SEM, EDS, FTIR, HRTEM, SAED and band-bending method. Our results show that oxidized interlayer imposes compressive stresses to AlN layer, developing a polycrystalline deposition. Indeed, when film thickness is over 900 nm, influence of oxidized interlayer diminishes and crystallographic orientation changes to the (0 0 0 2) one, i.e., columnar structure, and stress relief is induced (there is a transition from compressive to tensile stress). Also, we propose a growth scenario to explain this behaviour.

  3. Low-temperature growth of gallium nitride films by inductively coupled-plasma-enhanced reactive magnetron sputtering

    SciTech Connect

    Ni, Chih-Jui; Chau-Nan Hong, Franklin

    2014-05-15

    Gallium nitride (GaN) films were grown on sapphire substrate by reactive magnetron sputtering. Inductively coupled-plasma (ICP) source was installed between the substrate holder and the sputtering target to increase the plasma density and the degree of ionization of nitrogen gas. Liquid Ga and Ar/N{sub 2} were used as the sputtering target and sputtering gases, respectively. X-ray diffraction measurements confirmed that the authors could grow high quality GaN crystallites at 500 °C. However, the crystalline GaN (0002) peak remained even by lowering the growth temperature down to 300 °C. The N:Ga ratio of the film grown at 500 °C was almost 1:1, and the nitrogen composition became higher toward the 1:1 N:Ga ratio with increasing the growth temperature. The high degree of ionization induced by ICP source was essential to the growth of high crystalline quality GaN films.

  4. Fabrication of porous noble metal thin-film electrode by reactive magnetron sputtering.

    PubMed

    Cho, Tae-Shin; Choi, Heonjin; Kim, Joosun

    2013-06-01

    Porous platinum films have been fabricated by reactive sputtering combined with subsequent thermal annealing. Using the SEM, XRD, XPS, and polarization resistance measurement techniques, the microstructural development of the film and its resultant electrochemical properties have been characterized. Pore evolution was understood as a result of the thermal grooving of platinum during annealing process. We demonstrated that crystallization should be followed by agglomeration for the evolution of porous microstructures. Furthermore, reaction sputtering affected the adhesion enhancement between the film and substrate compared to the film deposited by non-reactive sputtering. The polarization resistance of the porous platinum film was five times lower than that of the dense platinum film. At 600 degrees C the resistance of the porous film was 5.67 omega x cm2, and that of the dense film was 38 omega x cm2.

  5. Degradation and Characterization of Resorbable Phosphate-Based Glass Thin-Film Coatings Applied by Radio-Frequency Magnetron Sputtering.

    PubMed

    Stuart, Bryan W; Gimeno-Fabra, Miquel; Segal, Joel; Ahmed, Ifty; Grant, David M

    2015-12-16

    Quinternary phosphate-based glasses of up to 2.67 μm, deposited by radio-frequency magnetron sputtering, were degraded in distilled water and phosphate-buffered saline (PBS) to investigate their degradation characteristics. Magnetron-sputtered coatings have been structurally compared to their compositionally equivalent melt-quenched bulk glass counterparts. The coatings were found to have structurally variable surfaces to melt-quenched glass such that the respective bridging oxygen to nonbridging oxygen bonds were 34.2% to 65.8% versus 20.5% to 79.5%, forming metaphosphate (PO3)(-) (Q(2)) versus less soluble (P2O7)(4-) (Q(1)) and (PO4)(3-) (Q(0)), respectively. This factor led to highly soluble coatings, exhibiting a t(1/2) degradation dependence in the first 2 h in distilled water, followed by a more characteristic linear profile because the subsequent layers were less soluble. Degradation was observed to preferentially occur, forming voids characteristic of pitting corrosion, which was confirmed by the use of a focused ion beam. Coating degradation in PBS precipitated a (PO3)(-) metaphosphate, an X-ray amorphous layer, which remained adherent to the substrate and seemingly formed a protective diffusion barrier, which inhibited further coating degradation. The implications are that while compositionally similar, sputter-deposited coatings and melt-quenched glasses are structurally dissimilar, most notably, with regard to the surface layer. This factor has been attributed to surface etching of the as-deposited coating layer during deposition and variation in the thermal history between the processes of magnetron sputtering and melt quenching.

  6. Process-structure-property correlations in pulsed dc reactive magnetron sputtered vanadium oxide thin films

    SciTech Connect

    Venkatasubramanian, Chandrasekaran; Cabarcos, Orlando M.; Drawl, William R.; Allara, David L.; Ashok, S.; Horn, Mark W.; Bharadwaja, S. S. N.

    2011-11-15

    Cathode hysteresis in the reactive pulsed dc sputtering of a vanadium metal target was investigated to correlate the structural and electrical properties of the resultant vanadium oxide thin films within the framework of Berg's model [Berg et al., J. Vac. Sci. Technol. A 5, 202 (1987)]. The process hysteresis during reactive pulsed dc sputtering of a vanadium metal target was monitored by measuring the cathode (target) current under different total gas flow rates and oxygen-to-argon ratios for a power density of {approx}6.6.W/cm{sup 2}. Approximately 20%-25% hysteretic change in the cathode current was noticed between the metallic and oxidized states of the V-metal target. The extent of the hysteresis varied with changes in the mass flow of oxygen as predicted by Berg's model. The corresponding microstructure of the films changed from columnar to equiaxed grain structure with increased oxygen flow rates. Micro-Raman spectroscopy indicates subtle changes in the film structure as a function of processing conditions. The resistivity, temperature coefficient of resistance, and charge transport mechanism, obeying the Meyer-Neldel relation [Meyer and Neldel, Z. Tech. Phys. (Leipzig) 12, 588 (1937)], were correlated with the cathode current hysteric behavior.

  7. High-rate reactive magnetron sputtering of zirconia films for laser optics applications

    NASA Astrophysics Data System (ADS)

    Juškevičius, K.; Audronis, M.; Subačius, A.; Drazdys, R.; Juškėnas, R.; Matthews, A.; Leyland, A.

    2014-09-01

    ZrO2 exhibits low optical absorption in the near-UV range and is one of the highest laser-induced damage threshold (LIDT) materials; it is, therefore, very attractive for laser optics applications. This paper reports explorations of reactive sputtering technology for deposition of ZrO2 films with low extinction coefficient k values in the UV spectrum region at low substrate temperature. A high deposition rate (64 % of the pure metal rate) process is obtained by employing active feedback reactive gas control which creates a stable and repeatable deposition processes in the transition region. Substrate heating at 200 °C was found to have no significant effect on the optical ZrO2 film properties. The addition of nitrogen to a closed-loop controlled process was found to have mostly negative effects in terms of deposition rate and optical properties. Open-loop O2 gas-regulated ZrO2 film deposition is slow and requires elevated (200 °C) substrate temperature or post-deposition annealing to reduce absorption losses. Refractive indices of the films were distributed in the range n = 2.05-2.20 at 1,000 nm and extinction coefficients were in the range k = 0.6 × 10-4 and 4.8 × 10-3 at 350 nm. X-ray diffraction analysis showed crystalline ZrO2 films consisted of monoclinic + tetragonal phases when produced in Ar/O2 atmosphere and monoclinic + rhombohedral or a single rhombohedral phase when produced in Ar/O2 + N2. Optical and physical properties of the ZrO2 layers produced in this study are suitable for high-power laser applications in the near-UV range.

  8. In vitro enhancement of SAOS-2 cell calcified matrix deposition onto radio frequency magnetron sputtered bioglass-coated titanium scaffolds.

    PubMed

    Saino, Enrica; Maliardi, Valentina; Quartarone, Eliana; Fassina, Lorenzo; Benedetti, Laura; De Angelis, Maria Gabriella Cusella; Mustarelli, Piercarlo; Facchini, Alessandro; Visai, Livia

    2010-03-01

    In bone tissue engineering, bioglass coating of titanium (Ti) scaffolds has drawn attention as a method to improve osteointegration and implant fixation. In this in vitro study, bioactive glass layers with an approximate thickness of 1 microm were deposited at 200 degrees C onto a three-dimensional Ti-6Al-4V scaffold using a radio frequency (r.f.) magnetron sputtering system. After incubation with SAOS-2 human osteoblasts, in comparison with the uncoated scaffolds, the bioglass-coated scaffolds showed a twofold increase in cell proliferation (p < 0.05) up to 68.4 x 10(6), and enhanced the deposition of extracellular matrix components such as decorin, fibronectin, osteocalcin, osteonectin, osteopontin, and type-I and -III collagens (p < 0.05). Calcium deposition was twofold greater on the bioglass-coated scaffolds (p < 0.05). The immunofluorescence related to the preceding bone matrix proteins and calcium showed their colocalization to the cell-rich areas. Alkaline phosphatase activity increased twofold (p < 0.001) and its protein content was threefold higher with respect to the uncoated sample. Quantitative reverse transcriptase-polymerase chain reaction analysis revealed upregulated transcription specific for type-I collagen and osteopontin (p < 0.001). All together, these results demonstrate that the bioglass coating of the three-dimensional Ti scaffolds by the r.f. magnetron sputtering technique determines an in vitro increase of the bone matrix elaboration and may potentially have a clinical benefit.

  9. Pulsed dc self-sustained magnetron sputtering

    SciTech Connect

    Wiatrowski, A.; Posadowski, W. M.; Radzimski, Z. J.

    2008-09-15

    The magnetron sputtering has become one of the commonly used techniques for industrial deposition of thin films and coatings due to its simplicity and reliability. At standard magnetron sputtering conditions (argon pressure of {approx}0.5 Pa) inert gas particles (necessary to sustain discharge) are often entrapped in the deposited films. Inert gas contamination can be eliminated during the self-sustained magnetron sputtering (SSS) process, where the presence of the inert gas is not a necessary requirement. Moreover the SSS process that is possible due to the high degree of ionization of the sputtered material also gives a unique condition during the transport of sputtered particles to the substrate. So far it has been shown that the self-sustained mode of magnetron operation can be obtained using dc powering (dc-SSS) only. The main disadvantage of the dc-SSS process is its instability related to random arc formation. In such case the discharge has to be temporarily extinguished to prevent damaging both the magnetron source and power supply. The authors postulate that pulsed powering could protect the SSS process against arcs, similarly to reactive pulsed magnetron deposition processes of insulating thin films. To put this concept into practice, (i) the high enough plasma density has to be achieved and (ii) the type of pulsed powering has to be chosen taking plasma dynamics into account. In this article results of pulsed dc self-sustained magnetron sputtering (pulsed dc-SSS) are presented. The planar magnetron equipped with a 50 mm diameter and 6 mm thick copper target was used during the experiments. The maximum target power was about 11 kW, which corresponded to the target power density of {approx}560 W/cm{sup 2}. The magnetron operation was investigated as a function of pulse frequency (20-100 kHz) and pulse duty factor (50%-90%). The discharge (argon) extinction pressure level was determined for these conditions. The plasma emission spectra (400-410 nm range

  10. Microstructural Properties of NC-Si/SiO2 Films IN SITU Grown by Reactive Magnetron Co-Sputtering

    NASA Astrophysics Data System (ADS)

    Lu, Wanbing; Guo, Shaogang; Wang, Jiantao; Li, Yun; Wang, Xinzhan; Yu, Gengxi; Fan, Shanshan; Fu, Guangsheng

    2012-01-01

    Nanocrystalline silicon embedded in silicon oxide (nc-Si/SiO2) films have been in situ grown at a low substrate temperature of 300°C by reactive magnetron co-sputtering of Si and SiO2 targets in a mixed Ar/H2 discharge. The influences of H2 flow rate (FH) on the microstructural properties of the deposited nc-Si/SiO2 films were investigated. The results of XRD and the deposition rate of nc-Si/SiO2 films show that the introduction of H2 contributes to the growth of nc-Si grains in silicon oxide matrix. With further increasing FH, the average size of nc-Si grains increases and the deposition rate of nc-Si/SiO2 films decreases gradually. Fourier transform infrared spectra analyses reveal that introduction of hydrogen contributes to the phase separation of nc-Si and SiOx in the deposited films. Moreover, the Si-O4-nSin(n = 0, 1) concentration of the deposited nc-Si/SiO2 films reduces with the increase of FH, while that of Si-O4-nSin(n = 2, 3) concentration increases. These results can be explained by that active hydrogen atoms increase the probability of reducing oxygen from precursor in the plasma and prompting oxygen desorption from the growing surface. This low-temperature procedure for preparing nc-Si/SiO2 films opens up the possibility of fabricating the silicon-based thin-film solar cells onto low-cost glass substrates using nc-Si/SiO2 films.

  11. High-rate deposition of MgO by reactive ac pulsed magnetron sputtering in the transition mode

    SciTech Connect

    Kupfer, H.; Kleinhempel, R.; Richter, F.; Peters, C.; Krause, U.; Kopte, T.; Cheng, Y.

    2006-01-15

    A reactive ac pulsed dual magnetron sputtering process for MgO thin-film deposition was equipped with a closed-loop control of the oxygen flow rate (F{sub O2}) using the 285 nm magnesium radiation as input. Owing to this control, most of the unstable part of the partial pressure versus flowrate curve became accessible. The process worked steadily and reproducible without arcing. A dynamic deposition rate of up to 35 nm m/min could be achieved, which was higher than in the oxide mode by about a factor of 18. Both process characteristics and film properties were investigated in this work in dependence on the oxygen flow, i.e., in dependence on the particular point within the transition region where the process is operated. The films had very low extinction coefficients (<5x10{sup -5}) and refractive indices close to the bulk value. They were nearly stoichiometric with a slight oxygen surplus (Mg/O=48/52) which was independent of the oxygen flow. X-ray diffraction revealed a prevailing (111) orientation. Provided that appropriate rf plasma etching was performed prior to deposition, no other than the (111) peak could be detected. The intensity of this peak increased with increasing F{sub O{sub 2}}, indicating an even more pronounced (111) texture. The ion-induced secondary electron emission coefficient (iSEEC) was distinctly correlated with the markedness of the (111) preferential orientation. Both refractive index and (111) preferred orientation (which determines the iSEEC) were found to be improved in comparison with the MgO growth in the fully oxide mode. Consequently, working in the transition mode is superior to the oxide mode not only with respect to the growth rate, but also to most important film properties.

  12. Reactive magnetron cosputtering of hard and conductive ternary nitride thin films: Ti-Zr-N and Ti-Ta-N

    SciTech Connect

    Abadias, G.; Koutsokeras, L. E.; Dub, S. N.; Tolmachova, G. N.; Debelle, A.; Sauvage, T.; Villechaise, P.

    2010-07-15

    Ternary transition metal nitride thin films, with thickness up to 300 nm, were deposited by dc reactive magnetron cosputtering in Ar-N{sub 2} plasma discharges at 300 deg. C on Si substrates. Two systems were comparatively studied, Ti-Zr-N and Ti-Ta-N, as representative of isostructural and nonisostructural prototypes, with the aim of characterizing their structural, mechanical, and electrical properties. While phase-separated TiN-ZrN and TiN-TaN are the bulk equilibrium states, Ti{sub 1-x}Zr{sub x}N and Ti{sub 1-y}Ta{sub y}N solid solutions with the Na-Cl (B1-type) structure could be stabilized in a large compositional range (up to x=1 and y=0.75, respectively). Substituting Ti atoms by either Zr or Ta atoms led to significant changes in film texture, microstructure, grain size, and surface morphology, as evidenced by x-ray diffraction, x-ray reflectivity, and scanning electron and atomic force microscopies. The ternary Ti{sub 1-y}Ta{sub y}N films exhibited superior mechanical properties to Ti{sub 1-x}Zr{sub x}N films as well as binary compounds, with hardness as high as 42 GPa for y=0.69. All films were metallic, the lowest electrical resistivity {rho}{approx}65 {mu}{Omega} cm being obtained for pure ZrN, while for Ti{sub 1-y}Ta{sub y}N films a minimum was observed at y{approx}0.3. The evolution of the different film properties is discussed based on microstructrural investigations.

  13. Magnetron theory

    NASA Astrophysics Data System (ADS)

    Riyopoulos, Spilios

    1996-03-01

    A guiding center fluid theory is applied to model steady-state, single mode, high-power magnetron operation. A hub of uniform, prescribed density, feeds the current spokes. The spoke charge follows from the continuity equation and the incompressibility of the guiding center flow. Included are the spoke self-fields (DC and AC), obtained by an expansion around the unperturbed (zero-spoke charge) flow in powers of ν/V1, ν, and V1 being the effective charge density and AC amplitude. The spoke current is obtained as a nonlinear function of the detuning from the synchronous (Buneman-Hartree, BH) voltage Vs; the spoke charge is included in the self-consistent definition of Vs. It is shown that there is a DC voltage region of width ‖V-Vs‖˜V1, where the spoke width is constant and the spoke current is simply proportional to the AC voltage. The magnetron characteristic curves are ``flat'' in that range, and are approximated by a linear expansion around Vs. The derived formulas differ from earlier results [J. F. Hull, in Cross Field Microwave Devices, edited by E. Okress (Academic, New York, 1961), pp. 496-527] in (a) there is no current cutoff at synchronism; the tube operates well below as well above the BH voltage; (b) the characteristics are single valued within the synchronous voltage range; (c) the hub top is not treated as virtual cathode; and (d) the hub density is not equal to the Brillouin density; comparisons with tube measurements show the best agreement for hub density near half the Brillouin density. It is also shown that at low space charge and low power the gain curve is symmetric relative to the voltage (frequency) detuning. While symmetry is broken at high-power/high space charge magnetron operation, the BH voltage remains between the current cutoff voltages.

  14. Characteristic corrosion resistance of nanocrystalline TiN films prepared by high density plasma reactive magnetron sputtering.

    PubMed

    Kim, J H; Kang, C G; Kim, Y T; Cheong, W S; Song, P K

    2013-07-01

    Nanocytalline TiN films were deposited on non-alkali glass and Al substrates by reactive DC magnetron sputtering (DCMS) with an electromagnetic field system (EMF). The microstructure and corrosion resistance of the TiN-coated Al substrates were estimated by X-ray diffraction (XRD), scanning electron microscopy (SEM) and electrochemical methods. All the TiN films shows that they have a (111) preferred orientation at room temperature. TiN films deposited on Al substrate using only DCMS 400 W showed a sheet resistance of 3.22 x 10-1 omega/symbol see texts (resistivity, 3.22 x 10-5 omegacm). On the other hand, a relatively low sheet resistance of 1.91 x 10-1 omega/symbol see text (1.91 x 10-5 omegacm) was obtained for the dense nanocrystalline TiN film deposited on Al substrate using DCMS 375 W+ EMF 25 W, indicating that the introduction of an EMF system enhanced the electrical properties of the TiN film. TiN films deposited on Al substrate at 400 degreesC had a (200) preferred orientation with the lowest sheet resistance of 1.28x10-1 omega/symbol see texts (1.28 x 10-5 omegacm) which was attributed to reduced nano size defects and an improvement of the crystallinity. Potentiostatic and Potentiodynamic tests with a TiN-coated Al showed good corrosion resistance (l/corr, = 2.03 microA/cm2, Ecorr = -348 mV) compared to the uncoated Al substrate (/corr = 4.45 microA/cm2, Ecorr = -650 mV). Furthermore, EMF system showed that corrosion resistance of the TiN film also was enhanced compared to DCMS only. For the TiN film deposited on Al substrate at 400 degreesC, corrosion current and potential was 0.63 micro/cm2 and -1.5 mV, respectively. This improved corrosion resistance of the TiN film could be attributed to the densification of the film caused by enhancement of nitrification with increasing high reactive nitrogen radicals.

  15. Structural and nanomechanical properties of BiFeO3 thin films deposited by radio frequency magnetron sputtering.

    PubMed

    Jian, Sheng-Rui; Chang, Huang-Wei; Tseng, Yu-Chin; Chen, Ping-Han; Juang, Jenh-Yih

    2013-06-25

    The nanomechanical properties of BiFeO3 (BFO) thin films are subjected to nanoindentation evaluation. BFO thin films are grown on the Pt/Ti/SiO2/Si substrates by using radio frequency magnetron sputtering with various deposition temperatures. The structure was analyzed by X-ray diffraction, and the results confirmed the presence of BFO phases. Atomic force microscopy revealed that the average film surface roughness increased with increasing of the deposition temperature. A Berkovich nanoindenter operated with the continuous contact stiffness measurement option indicated that the hardness decreases from 10.6 to 6.8 GPa for films deposited at 350°C and 450°C, respectively. In contrast, Young's modulus for the former is 170.8 GPa as compared to a value of 131.4 GPa for the latter. The relationship between the hardness and film grain size appears to follow closely with the Hall-Petch equation.

  16. Formation of Nanoparticles by Control of Electron Temperature in Hollow-Typed Magnetron Radio Frequency CH4/H2 Plasma

    NASA Astrophysics Data System (ADS)

    Emi, Junichi; Kato, Kohgi; Abe, Toshimi; Iizuka, Satoru

    2006-10-01

    In this study, we investigate the effects of electron temperature Te on the production of nanoparticles by using the grid-biasing method in hollow-typed magnetron radio frequency (RF) CH4/H2 plasma. We find that nanoparticles are produced in low-Te plasma. On the other hand, thin film depositions, such as nanowalls, are mainly observed and almost no nanoparticles are created in high-Te plasma. This implies that a reduction in the CH2/CH3 radical ratio is important for producing nanoparticles, together with a reduction in sheath potential in front of the substrate. The change in electron temperature in plasma has a marked effect on film quality.

  17. Microstructural properties of phosphorus-doped p-type ZnO grown by radio-frequency magnetron sputtering

    SciTech Connect

    Oh, Min-Suk; Hwang, Dae-Kue; Choi, Yong-Seok; Kang, Jang-Won; Park, Seong-Ju; Hwang, Chi-Sun; Cho, Kyoung Ik

    2008-09-15

    Phosphorus (P)-doped ZnO thin films were grown by radio-frequency magnetron sputtering to study the microstructural properties of p-type ZnO. As-grown P-doped ZnO, a semi-insulator, was converted to p-type ZnO after being annealed at 800 deg. C in an N{sub 2} ambient. X-ray diffraction, secondary-ion-mass spectrometry, and Hall effect measurements indicated that P{sub 2}O{sub 5} phases in as-grown P-doped ZnO disappeared after thermal annealing to form a substitutional P at an O lattice site, which acts as an acceptor in P-doped ZnO. Transmission electron microscopy showed that the formation of stacking faults was facilitated to release the strain in P-doped ZnO during post-thermal annealing.

  18. Highly oriented {delta}-Bi{sub 2}O{sub 3} thin films stable at room temperature synthesized by reactive magnetron sputtering

    SciTech Connect

    Lunca Popa, P.; Kerdsongpanya, S.; Lu, J.; Eklund, P.; Sonderby, S.; Bonanos, N.

    2013-01-28

    We report the synthesis by reactive magnetron sputtering and structural characterization of highly (111)-oriented thin films of {delta}-Bi{sub 2}O{sub 3}. This phase is obtained at a substrate temperature of 150-200 Degree-Sign C in a narrow window of O{sub 2}/Ar ratio in the sputtering gas (18%-20%). Transmission electron microscopy and x-ray diffraction reveal a polycrystalline columnar structure with (111) texture. The films are stable from room temperature up to 250 Degree-Sign C in vacuum and 350 Degree-Sign C in ambient air.

  19. Deposition and characterization of zirconium nitride (ZrN) thin films by reactive magnetron sputtering with linear gas ion source and bias voltage

    SciTech Connect

    Kavitha, A.; Kannan, R.; Subramanian, N. Sankara; Loganathan, S.

    2014-04-24

    Zirconium nitride thin films have been prepared on stainless steel substrate (304L grade) by reactive cylindrical magnetron sputtering method with Gas Ion Source (GIS) and bias voltage using optimized coating parameters. The structure and surface morphologies of the ZrN films were characterized using X-ray diffraction, atomic microscopy and scanning electron microscopy. The adhesion property of ZrN thin film has been increased due to the GIS. The coating exhibits better adhesion strength up to 10 N whereas the ZrN thin film with bias voltage exhibits adhesion up to 500 mN.

  20. Correlation between Microstructure and Mechanical Properties ofTiC Films Produced by Vacuum arc Deposition and Reactive MagnetronSputtering

    SciTech Connect

    Monteiro, O.R.; Delplancke-Ogletree, M.P.; Winand, R.; Brown, I.G.

    1999-07-29

    We have studied the synthesis of TiC films by vacuum arc deposition and reactive magnetron sputtering over a wide range of compositions. The films were deposited on silicon and tool steel. The films were characterized by various techniques: Auger electron and X-ray photoelectron spectroscopies, Rutherford backscattering, transmission electron diffraction and X-ray diffraction. Mechanical properties such as stress, adhesion, friction coefficient and wear resistance were obtained by carrying measurements of the curvature of the silicon substrate, pull tests, and ball-on-disk tests, respectively.

  1. Nanostructural and mechanical properties of nanocomposite nc-TiC/a-C:H films deposited by reactive unbalanced magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Zehnder, T.; Schwaller, P.; Munnik, F.; Mikhailov, S.; Patscheider, J.

    2004-04-01

    Thin films of nc-TiC/a-C:H nanocomposite have been deposited by reactive magnetron sputtering at substrate bias values of -240 and -91 V. The grain size and grain separation, which together define the nanostructure, are correlated to the amount of the amorphous phase. From the size of the TiC grains measured by x-ray diffraction and the amorphous hydrogenated carbon (a-C:H) phase content determined by x-ray photoelectron spectroscopy, the mean grain separation is estimated using a simple model for the nanostructure. Films deposited at -240 V show a hardness enhancement for a-C:H phase contents in the range 10% to 30% with TiC grain sizes around 5 nm. The mean grain separation for such films was estimated to be 0.3 nm. Films with higher a-C:H phase contents still have 5 nm small grains, but their mean grain separation is larger than 0.5 nm; their hardness is thus determined by the properties of the amorphous matrix. A less pronounced hardness enhancement is observed for films deposited at -91 V. They have larger grains and larger mean gain separations and show smaller hardness values. The hardness of the films, among other mechanical properties, is controlled by the nanostructure. Raman measurements have shown that a-C:H is present in films with mean grain separation down to 0.2 nm. Coefficients of friction against steel lower than 0.3, independent of the substrate bias, are found for films with mean grain separations as low as 0.15 nm. Self-lubrication due to a-C:H can explain the observed friction behavior, although the presence of a-C:H cannot be proved by Raman spectroscopy for films with mean grain separations smaller than 0.2 nm. It is shown that the substrate bias is crucial in obtaining increased hardness of nc-TiC/a-C:H nanocomposite thin films. In contrast to the hardness of the coatings, their friction behavior is not affected by the substrate bias.

  2. Reactive magnetron sputtering of highly (001)-textured WS2-x films: Influence of Ne+, Ar+ and Xe+ ion bombardment on the film growth

    NASA Astrophysics Data System (ADS)

    Ellmer, K.; Seeger, S.; Sieber, I.; Bohne, W.; Röhrich, J.; Strub, E.; Mientus, R.

    2006-02-01

    Tungsten disulfide WS2 is a layer-type semi-conductor with an energy band gap and an absorption coefficient making it suitable as an absorber for thin film solar cells. In the article [1] WS2-x films were pre-pared by reactive magnetron sputtering from a metallic tungsten target in Ar-H2S atmospheres.The cover figure shows in situ energy-dispersive X-ray diffraction patterns for films deposited at different substrate potentials, i.e. for deposition conditions with ion assistance at different ion energies. These spectra and the corresponding SEM photographs of the film morphology show the strong influence of the ion energy on the film growth. The crystallographic struc-ture of WS2-x is shown between the two SEM pictures.The first author, Klaus Ellmer, is working at the Hahn-Meitner-Institut Berlin, Dept. of Solar Energy Research. His research fields are thin film deposition by reactive magnetron sputtering for solar cells, plasma characterization, in situ energy-dispersive X-ray diffraction and electronic transport in transpar-ent conductive oxides.

  3. Substrate temperature dependent surface morphology and photoluminescence of germanium quantum dots grown by radio frequency magnetron sputtering.

    PubMed

    Samavati, Alireza; Othaman, Zulkafli; Ghoshal, Sib Krishna; Dousti, Mohammad Reza; Kadir, Mohammed Rafiq Abdul

    2012-10-09

    The visible luminescence from Ge nanoparticles and nanocrystallites has generated interest due to the feasibility of tuning band gap by controlling the sizes. Germanium (Ge) quantum dots (QDs) with average diameter ~16 to 8 nm are synthesized by radio frequency magnetron sputtering under different growth conditions. These QDs with narrow size distribution and high density, characterized using atomic force microscopy (AFM) and field emission scanning electron microscopy (FESEM) are obtained under the optimal growth conditions of 400 °C substrate temperature, 100 W radio frequency powers and 10 Sccm Argon flow. The possibility of surface passivation and configuration of these dots are confirmed by elemental energy dispersive X-ray (EDX) analysis. The room temperature strong visible photoluminescence (PL) from such QDs suggests their potential application in optoelectronics. The sample grown at 400 °C in particular, shows three PL peaks at around ~2.95 eV, 3.34 eV and 4.36 eV attributed to the interaction between Ge, GeO(x) manifesting the possibility of the formation of core-shell structures. A red shift of ~0.11 eV in the PL peak is observed with decreasing substrate temperature. We assert that our easy and economic method is suitable for the large-scale production of Ge QDs useful in optoelectronic devices.

  4. Nitrogen-doped p-type ZnO films prepared from nitrogen gas radio-frequency magnetron sputtering

    SciTech Connect

    Tu, M.-L.; Su, Y.-K.; Ma, C.-Y.

    2006-09-01

    Wide band gap nitrogen-doped p-type ZnO films are prepared by radio-frequency magnetron sputtering from a 99.99% purity ZnO target. The sputtering gas is Ar mixed with various flow rates of nitrogen gas. Hole concentrations increase from 1.89x10{sup 15} to 2.11x10{sup 19} cm{sup -3} as the N{sub 2} flow rate decreases from 15 to 6 SCCM (SCCM denotes cubic centimeter per minute at STP), i.e., increasing N{sub 2} flow rate above 6 SCCM decreases the p-type carrier concentration. Microphotoluminescence (PL) spectra peaks are in the near-UV range and change from 384 nm (3.23 eV) to 374 nm (3.32 eV) with increasing N{sub 2} flow rate. The PL peaks agree with the band gap of bulk ZnO, which comes from the recombination of free excitons. Raman spectra show six peaks: 436 (E{sub 2} high-frequency phonon mode for undoped ZnO film), 581 [A{sub 1} (LO) mode in ZnO:N film], 275, 508, 640, and 854 cm{sup -1} (local vibrational modes of Raman features in N-doped ZnO film)

  5. Structure and magnetic properties of hcp and fcc nanocrystalline thin Ni films and nanoparticles produced by radio frequency magnetron sputtering.

    PubMed

    Kapaklis, Vassilios; Pappas, Spiridon D; Poulopoulos, Panagiotis; Trachylis, Dimitrios; Schweiss, Peter; Politis, Constantin

    2010-09-01

    We report on the growth of thin Ni films by radio frequency magnetron sputtering in Ar-plasma. The growth temperature was about 350 K and the films were deposited on various substrates such as glass, silicon, sapphire and alumina. The thickness of the thinnest films was estimated by the appearance of Kiessig fringes up to about 2theta = 8 degrees in the small-angle X-ray diffraction pattern, as expected for high-quality atomically-flat thin films. With the help of this, a quartz balance system was calibrated and used for measuring the thickness of thicker samples with an accuracy of better than 5%. Structural characterization via X-ray diffraction and high resolution transmission electron microscopy revealed an Ar-gas pressure window, where single phase hcp Ni films may be grown. The magnetic response of the Ni films was checked at room temperature via a newly established and fully automatic polar magneto-optic Kerr effect magnetometer. The hcp films show no magnetic response. Interestingly, the magnetic saturation field of fcc films deposited at low Ar pressure is comparable to the one of bulk Ni, while the one of fcc films deposited at high Ar pressures is decreased, revealing the presence of residual strain in the films. Finally, it is shown that it is possible to form films which contain magnetic Ni fcc nanoparticles in a non-magnetic hcp matrix, i.e., a system interesting for technological applications demanding a single Ni target for its production.

  6. Radio Frequency Magnetron Sputtering Deposition of TiO2 Thin Films and Their Perovskite Solar Cell Applications.

    PubMed

    Chen, Cong; Cheng, Yu; Dai, Qilin; Song, Hongwei

    2015-12-03

    In this work, we report a physical deposition based, compact (cp) layer synthesis for planar heterojunction perovskite solar cells. Typical solution-based synthesis of cp layer for perovskite solar cells involves low-quality of thin films, high-temperature annealing, non-flexible devices, limitation of large-scale production and that the effects of the cp layer on carrier transport have not been fully understood. In this research, using radio frequency magnetron sputtering (RFMS), TiO2 cp layers were fabricated and the thickness could be controlled by deposition time; CH3NH3PbI3 films were prepared by evaporation &immersion (E &I) method, in which PbI2 films made by thermal evaporation technique were immersed in CH3NH3I solution. The devices exhibit power conversion efficiency (PCE) of 12.1% and the photovoltaic performance can maintain 77% of its initial PCE after 1440 h. The method developed in this study has the capability of fabricating large active area devices (40 × 40 mm(2)) showing a promising PCE of 4.8%. Low temperature and flexible devices were realized and a PCE of 8.9% was obtained on the PET/ITO substrates. These approaches could be used in thin film based solar cells which require high-quality films leading to reduced fabrication cost and improved device performance.

  7. Radio Frequency Magnetron Sputtering Deposition of TiO2 Thin Films and Their Perovskite Solar Cell Applications

    NASA Astrophysics Data System (ADS)

    Chen, Cong; Cheng, Yu; Dai, Qilin; Song, Hongwei

    2015-12-01

    In this work, we report a physical deposition based, compact (cp) layer synthesis for planar heterojunction perovskite solar cells. Typical solution-based synthesis of cp layer for perovskite solar cells involves low-quality of thin films, high-temperature annealing, non-flexible devices, limitation of large-scale production and that the effects of the cp layer on carrier transport have not been fully understood. In this research, using radio frequency magnetron sputtering (RFMS), TiO2 cp layers were fabricated and the thickness could be controlled by deposition time; CH3NH3PbI3 films were prepared by evaporation & immersion (E & I) method, in which PbI2 films made by thermal evaporation technique were immersed in CH3NH3I solution. The devices exhibit power conversion efficiency (PCE) of 12.1% and the photovoltaic performance can maintain 77% of its initial PCE after 1440 h. The method developed in this study has the capability of fabricating large active area devices (40 × 40 mm2) showing a promising PCE of 4.8%. Low temperature and flexible devices were realized and a PCE of 8.9% was obtained on the PET/ITO substrates. These approaches could be used in thin film based solar cells which require high-quality films leading to reduced fabrication cost and improved device performance.

  8. Radio Frequency Magnetron Sputtering Deposition of TiO2 Thin Films and Their Perovskite Solar Cell Applications

    PubMed Central

    Chen, Cong; Cheng, Yu; Dai, Qilin; Song, Hongwei

    2015-01-01

    In this work, we report a physical deposition based, compact (cp) layer synthesis for planar heterojunction perovskite solar cells. Typical solution-based synthesis of cp layer for perovskite solar cells involves low-quality of thin films, high-temperature annealing, non-flexible devices, limitation of large-scale production and that the effects of the cp layer on carrier transport have not been fully understood. In this research, using radio frequency magnetron sputtering (RFMS), TiO2 cp layers were fabricated and the thickness could be controlled by deposition time; CH3NH3PbI3 films were prepared by evaporation & immersion (E & I) method, in which PbI2 films made by thermal evaporation technique were immersed in CH3NH3I solution. The devices exhibit power conversion efficiency (PCE) of 12.1% and the photovoltaic performance can maintain 77% of its initial PCE after 1440 h. The method developed in this study has the capability of fabricating large active area devices (40 × 40 mm2) showing a promising PCE of 4.8%. Low temperature and flexible devices were realized and a PCE of 8.9% was obtained on the PET/ITO substrates. These approaches could be used in thin film based solar cells which require high-quality films leading to reduced fabrication cost and improved device performance. PMID:26631493

  9. Simulation, fabrication and characterization of ZnO based thin film transistors grown by radio frequency magnetron sputtering.

    PubMed

    Singh, Shaivalini; Chakrabarti, P

    2012-03-01

    We report the performance of the thin film transistors (TFTs) using ZnO as an active channel layer grown by radio frequency (RF) magnetron sputtering technique. The bottom gate type TFT, consists of a conventional thermally grown SiO2 as gate insulator onto p-type Si substrates. The X-ray diffraction patterns reveal that the ZnO films are preferentially orientated in the (002) plane, with the c-axis perpendicular to the substrate. A typical ZnO TFT fabricated by this method exhibits saturation field effect mobility of about 0.6134 cm2/V s, an on to off ratio of 102, an off current of 2.0 x 10(-7) A, and a threshold voltage of 3.1 V at room temperature. Simulation of this TFT is also carried out by using the commercial software modeling tool ATLAS from Silvaco-International. The simulated global characteristics of the device were compared and contrasted with those measured experimentally. The experimental results are in fairly good agreement with those obtained from simulation.

  10. Low-temperature growth of InxGa1-xN films by radio-frequency magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Wang, J.; Shi, X. J.; Zhu, J.

    2013-01-01

    The low-temperature growth of InxGa1-xN films on quartz glass substrates utilizing radio-frequency magnetron sputtering is investigated. In the InxGa1-xN films prepared using an In-Ga alloy target, grazing incidence X-ray diffraction (GIXRD) peaks corresponding to wurtzite structure were observed. X-ray photoelectron spectroscopy (XPS) was applied to study the extent of oxygen contamination and chemical states, and secondary ion mass spectrometry (SIMS) was used to evaluate the distribution profiles of oxygen impurity in the as-grown InxGa1-xN thin films. XPS and SIMS analysis indicate that the entire thin films have oxide phases. However, no evidence of In2O3, Ga2O3, or indium oxynitride phases was shown in XRD studies. It may be predicted that the oxygen impurities formed amorphous oxide phases embedded in InxGa1-xN matrix. According to our findings, indium is a major phase in the InxGa1-xN thin films which suggests that a significant amount of indium remains un-reacted with N2. The optical transmittance spectra of the as-grown films show interference fringe patterns. The indium fraction x of the as-deposited InxGa1-xN thin films can be calculated out by the transmittance data.

  11. Improved electrochemical performance of LiCoO₂ electrodes with ZnO coating by radio frequency magnetron sputtering.

    PubMed

    Dai, Xinyi; Wang, Liping; Xu, Jin; Wang, Ying; Zhou, Aijun; Li, Jingze

    2014-09-24

    Surface modification of LiCoO2 is an effective method to improve its energy density and elongate its cycle life in an extended operation voltage window. In this study, ZnO was directly coated on as-prepared LiCoO2 composite electrodes via radio frequency (RF) magnetron sputtering. ZnO is not only coated on the electrode as thin film but also diffuses through the whole electrode due to the intrinsic porosity of the composite electrode and the high diffusivity of the deposited species. It was found that ZnO coating can significantly improve the cycling performance and the rate capability of the LiCoO2 electrodes in the voltage range of 3.0-4.5 V. The sample with an optimum coating thickness of 17 nm exhibits an initial discharge capacity of 191 mAh g(-1) at 0.2 C, and the capacity retention is 81% after 200 cycles. It also delivers superior rate performance with a reversible capacity of 106 mAh g(-1) at 10 C. The enhanced cycling performance and rate capability are attributed to the stabilized phase structure and improved lithium ion diffusion coefficient induced by ZnO coating as evidenced by X-ray diffraction, cyclic voltammetry, respectively.

  12. Growth of fullerene-like carbon nitride thin solid films by reactive magnetron sputtering; role of low-energy ion irradiation in determining microstructure and mechanical properties

    NASA Astrophysics Data System (ADS)

    Neidhardt, J.; Czigány, Zs.; Brunell, I. F.; Hultman, L.

    2003-03-01

    Fullerene-like (FL) carbon nitride (CNx) films were deposited on Si (100) substrates by dc reactive, unbalanced, magnetron sputtering in a N2/Ar mixture from a high-purity pyrolythic graphite cathode in a dual-magnetron system with coupled magnetic fields. The N2 fraction in the discharge gas (0%-100%) and substrate bias (-25 V; -40 V) was varied, while the total pressure (0.4 Pa) and substrate temperature (450 °C) was kept constant. The coupled configuration of the magnetrons resulted in a reduced ion flux density, leading to a much lower average energy per incorporated particle, due to a less focused plasma as compared to a single magnetron. This enabled the evolution of a pronounced FL microstructure. The nitrogen concentration in the films saturated rapidly at 14-18 at. %, as determined by elastic recoil analysis, with a minor dependence on the discharge conditions. No correlations were detected between the photoelectron N1s core level spectra and the different microstructures, as observed by high-resolution electron microscopy. A variety of distinct FL structures were obtained, ranging from structures with elongated and aligned nitrogen-containing graphitic sheets to disordered structures, however, not exclusively linked to the total N concentration in the films. The microstructure evolution has rather to be seen as in equilibrium between the two competing processes of adsorption and desorption of nitrogen-containing species at the substrate. This balance is shifted by the energy and number of arriving species as well as by the substrate temperature. The most exceptional structure, for lower N2 fractions, consists of well-aligned, multi-layered circular features (nano-onions) with an inner diameter of approximately 0.7 nm and successive shells at a distance of ˜0.35 nm up to a diameter of 5 nm. It is shown that the intrinsic stress formation is closely linked with the evolution and accommodation of the heavily bent fullerene-like sheets. The FL CNx

  13. Effect of nitrogen flow ratios on the structure and mechanical properties of (TiVCrZrY)N coatings prepared by reactive magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Tsai, Du-Cheng; Huang, Yen-Lin; Lin, Sheng-Ru; Liang, Shih-Chang; Shieu, Fuh-Sheng

    2010-12-01

    This study reports the influence of growth conditions on the characteristics of (TiVCrZrY)N coatings prepared by reactive magnetron sputtering at various N 2-to-total (N 2 + Ar) flow ratio, which is R N. The crystal structures, microstructure, and mechanical properties for different R N were characterized by electron spectroscopy for chemical analysis, X-ray diffraction, atomic force microscopy, field-emission-scanning electron microscopy, transmission electron microscopy, and nanoindentation. The results indicate that the TiVCrZrY alloy and nitride coatings have hexagonal close-packed (hcp)-type and sodium chloride (NaCl)-type solid-solution structures, respectively. The voids in the coatings are eliminated and the growth of the columnar crystal structures is inhibited along with an increasing R N. As a consequence, highly packed equiaxed amorphous structures with smooth surfaces are formed. The coatings accordingly achieved a pronounce hardness of 17.5 GPa when R N = 100%.

  14. Investigation of structural, optical and electrical properties of (Ti,Nb)Ox thin films deposited by high energy reactive magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Mazur, Michal; Kaczmarek, Danuta; Prociow, Eugeniusz; Domaradzki, Jaroslaw; Wojcieszak, Damian; Bocheński, Jakub

    2014-09-01

    In this work the results of investigations of the titanium-niobium oxides thin films have been reported. The thin films were manufactured with the aid of a modified reactive magnetron sputtering process. The aim of the research was the analysis of structural, optical and electrical properties of the deposited thin films. Additionally, the influence of post-process annealing on the properties of studied coatings has been presented. The as-deposited coatings were amorphous, while annealing at 873 K caused a structural change to the mixture of TiO2 anatase-rutile phases. The prepared thin films exhibited good transparency with transmission level of ca. 50 % and low resistivity varying from 2 Ωcm to 5×10-2 Ωcm, depending on the time and temperature of annealing. What is worth to emphasize, the sign of Seebeck coefficient changed after the annealing process from the electron to hole type electrical conduction.

  15. Fabrication and characterization of He-charged ODS-FeCrNi films deposited by a radio-frequency plasma magnetron sputtering technique

    NASA Astrophysics Data System (ADS)

    Liang, SONG; Xianping, WANG; Le, WANG; Ying, ZHANG; Wang, LIU; Weibing, JIANG; Tao, ZHANG; Qianfeng, FANG; Changsong, LIU

    2017-04-01

    He-charged oxide dispersion strengthened (ODS) FeCrNi films were prepared by a radio-frequency (RF) plasma magnetron sputtering method in a He and Ar mixed atmosphere at 150 °C. As a comparison, He-charged FeCrNi films were also fabricated at the same conditions through direct current (DC) plasma magnetron sputtering. The doping of He atoms and Y2O3 in the FeCrNi films was realized by the high backscattered rate of He ions and Y2O3/FeCrNi composite target sputtering method, respectively. Inductive coupled plasma (ICP) and x-ray photoelectron spectroscopy (XPS) analysis confirmed the existence of Y2O3 in FeCrNi films, and Y2O3 content hardly changed with sputtering He/Ar ratio. Cross-sectional scanning electron microscopy (SEM) shows that the FeCrNi films were composed of dense columnar nanocrystallines and the thickness of the films was obviously dependent on He/Ar ratio. Nanoindentation measurements revealed that the FeCrNi films fabricated through DC/RF plasma magnetron sputtering methods exhibited similar hardness values at each He/Ar ratio, while the dispersion of Y2O3 apparently increased the hardness of the films. Elastic recoil detection (ERD) showed that DC/RF magnetron sputtered FeCrNi films contained similar He amounts (∼17 at.%). Compared with the minimal change of He level with depth in DC-sputtered films, the He amount decreases gradually in depth in the RF-sputtered films. The Y2O3-doped FeCrNi films were shown to exhibit much smaller amounts of He owing to the lower backscattering possibility of Y2O3 and the inhibition effect of nano-sized Y2O3 particles on the He element.

  16. Amorphous indium-tin-zinc oxide films deposited by magnetron sputtering with various reactive gases: Spatial distribution of thin film transistor performance

    NASA Astrophysics Data System (ADS)

    Jia, Junjun; Torigoshi, Yoshifumi; Kawashima, Emi; Utsuno, Futoshi; Yano, Koki; Shigesato, Yuzo

    2015-01-01

    This work presents the spatial distribution of electrical characteristics of amorphous indium-tin-zinc oxide film (a-ITZO), and how they depend on the magnetron sputtering conditions using O2, H2O, and N2O as the reactive gases. Experimental results show that the electrical properties of the N2O incorporated a-ITZO film has a weak dependence on the deposition location, which cannot be explained by the bombardment effect of high energy particles, and may be attributed to the difference in the spatial distribution of both the amount and the activity of the reactive gas reaching the substrate surface. The measurement for the performance of a-ITZO thin film transistor (TFT) also suggests that the electrical performance and device uniformity of a-ITZO TFTs can be improved significantly by the N2O introduction into the deposition process, where the field mobility reach to 30.8 cm2 V-1 s-1, which is approximately two times higher than that of the amorphous indium-gallium-zinc oxide TFT.

  17. Amorphous indium-tin-zinc oxide films deposited by magnetron sputtering with various reactive gases: Spatial distribution of thin film transistor performance

    SciTech Connect

    Jia, Junjun; Torigoshi, Yoshifumi; Shigesato, Yuzo; Kawashima, Emi; Utsuno, Futoshi; Yano, Koki

    2015-01-12

    This work presents the spatial distribution of electrical characteristics of amorphous indium-tin-zinc oxide film (a-ITZO), and how they depend on the magnetron sputtering conditions using O{sub 2}, H{sub 2}O, and N{sub 2}O as the reactive gases. Experimental results show that the electrical properties of the N{sub 2}O incorporated a-ITZO film has a weak dependence on the deposition location, which cannot be explained by the bombardment effect of high energy particles, and may be attributed to the difference in the spatial distribution of both the amount and the activity of the reactive gas reaching the substrate surface. The measurement for the performance of a-ITZO thin film transistor (TFT) also suggests that the electrical performance and device uniformity of a-ITZO TFTs can be improved significantly by the N{sub 2}O introduction into the deposition process, where the field mobility reach to 30.8 cm{sup 2} V{sup –1} s{sup –1}, which is approximately two times higher than that of the amorphous indium-gallium-zinc oxide TFT.

  18. Energy fluxes in a radio-frequency magnetron discharge for the deposition of superhard cubic boron nitride coatings

    NASA Astrophysics Data System (ADS)

    Bornholdt, S.; Ye, J.; Ulrich, S.; Kersten, H.

    2012-12-01

    Energy flux measurements by a calorimetric probe in a rf-magnetron plasma used for the deposition of super-hard c-BN coatings are presented and discussed. Argon as working gas is used for sputtering a h-BN target. Adding a certain amount of N2 is essential for the formation of stoichiometric BN films, since a lack of nitrogen will lead to boron rich films. Subsequently, the contributions of different plasma species, surface reactions, and film growth to the resulting variation of the substrate temperature in dependence on nitrogen admixture are estimated and discussed. In addition, SRIM simulations are performed to estimate the energy influx by sputtered neutral atoms. The influence of magnetron target power and oxygen admixture (for comparison with nitrogen) to the process gas on the total energy flux is determined and discussed qualitatively, too. The results indicate that variation of the energy influx due to additional nitrogen flow, which causes a decrease of electron and ion densities, electron temperature and plasma potential, is negligible, while the admixture of oxygen leads to a drastic increase of the energy influx. The typical hysteresis effect which can be observed during magnetron sputtering in oxygen containing gas mixtures has also been confirmed in the energy influx measurements for the investigated system. However, the underlying mechanism is not understood yet, and will be addressed in further investigations.

  19. [Effects of Temperature on the Preparation of Al/Zn3N2 Thin Films Using Magnetron Reactive Sputtering].

    PubMed

    Feng, Jun-qin; Chen, Jun-fang

    2015-08-01

    The effects of substrate temperature on the plasma active species were investigated by plasma optical emission spectroscopy. With increasing substrate temperature, the characteristic spectroscopy intensity of the first positive series of N2* (B(3)Πg-->A(3)Σu(+)), the second positive N2* (C(3)Πu-->B(3)Πg), the first negative series N2(+)* (B(2)Σu(+)-->X(2)Σg(+)) and Zn* are increased. Due to the substrate temperature, each ion kinetic energy is increased and the collision ionization intensified in the chamber. That leading to plasma ion density increase. These phenomenons's show that the substrate temperature raises in a certain range was conducive to zinc nitride thin films growth. Zn3N2 thin films were prepared on Al films using ion sources-assisted magnetron sputtering deposition method. The degree of crystalline of the films was examined with X-ray diffraction (XRD). The results show that has a dominant peak located at 34.359° in room temperature, which was corresponding to the (321) plane of cubic anti-bixbyite zinc nitride structure (JCPDS Card No35-0762). When the substrate temperature was 100 °C, in addition to the (321) reflection, more diffraction peaks appeared corresponding to the (222), (400) and (600) planes, which were located at 31.756°, 36.620° and 56.612° respectively. When the substrate temperature was 200 °C, in addition to the (321), (222), (400) and (600) reflection, more new diffraction peaks also appeared corresponding to the (411), (332), (431) and (622) planes, which were located at 39.070, 43.179°, 47.004° and 62.561° respectively. These results show the film crystalline increased gradually with raise the substrate temperature. XP-1 profilometer were used to analyze the thickness of the Zn3N2 films. The Zn3N2 films deposited on Al films in mixture gas plasma had a deposition rate of 2.0, 2.2, and 2.7 nm · min(-1). These results indicate that the deposition rate was gradually enhanced as substrate temperature increased

  20. Transparent conductive F-doped SnO2 films prepared by RF reactive magnetron sputtering at low substrate temperature

    NASA Astrophysics Data System (ADS)

    Zhu, B. L.; Yang, Y. T.; Hu, W. C.; Wu, J.; Gan, Z. H.; Liu, J.; Zeng, D. W.; Xie, C. S.

    2017-04-01

    To obtain highly transparent conductive F-doped SnO2 films by magnetron sputtering at low substrate temperatures, a new method of sputtering high-density SnF2-Sn target in Ar + O2 atmosphere was adopted in the present study. The structural, electrical, and optical properties of the films prepared were investigated as a function of O2 flux. The results indicate that the films shows SnO2 phase only at O2 flux above a critical value (0.8 sccm), and the crystallinity of SnO2 phase is improved with increasing O2 flux. The resistivity of the films steeply decreases once O2 flux is above the critical value, but it greatly increases as O2 flux is too high. Only in intermediate range of O2 flux, the films with low resistivity can be obtained. As O2 flux is above the critical value, both the transmittances in visible light range and E g of the films show steeply increase, and the PL spectra of the film show distinct emission characteristics. Furthermore, the position and intensity of PL emission peaks are similar when O2 flux is above the critical value, and the emission mechanism can be attributed to electron transitions mediated by defect levels in the bandgap, such as V O and F O. Just because of formation of SnO2 phase in the films and existence of relatively larger amount of V O and F O, the films show low resistivity and high transmittance at suitable O2 fluxes.

  1. Transmission photocathodes based on stainless steel mesh and quartz glass coated with N-doped DLC thin films prepared by reactive magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Balalykin, N. I.; Huran, J.; Nozdrin, M. A.; Feshchenko, A. A.; Kobzev, A. P.; Arbet, J.

    2016-03-01

    The influence was investigated of N-doped diamond-like carbon (DLC) films properties on the quantum efficiency of a prepared transmission photocathode. N-doped DLC thin films were deposited on a silicon substrate, a stainless steel mesh and quartz glass (coated with 5 nm thick Cr adhesion film) by reactive magnetron sputtering using a carbon target and gas mixture Ar, 90%N2+10%H2. The elements' concentration in the films was determined by RBS and ERD. The quantum efficiency was calculated from the measured laser energy and the measured cathode charge. For the study of the vectorial photoelectric effect, the quartz type photocathode was irradiated by intensive laser pulses to form pin-holes in the DLC film. The quantum efficiency (QE), calculated at a laser energy of 0.4 mJ, rose as the nitrogen concentration in the DLC films was increased and rose dramatically after the micron-size perforation in the quartz type photocathodes.

  2. The photoactivity of titanium dioxide coatings with silver nanoparticles prepared by sol-gel and reactive magnetron sputtering methods - comparative studies

    NASA Astrophysics Data System (ADS)

    Kądzioła, Kinga; Piwoński, Ireneusz; Kisielewska, Aneta; Szczukocki, Dominik; Krawczyk, Barbara; Sielski, Jan

    2014-01-01

    Titanium dioxide coatings were deposited on silicon substrates using two different methods: sol-gel dip-coating (SG) and reactive magnetron sputtering (MS). In order to obtain anatase phase, as-prepared coatings were calcined at 500 °C in air. Subsequently, silver nanoparticles (AgNPs) were grown on the surface of TiO2 coatings by photoreduction of silver ions, initiated by illumination of the UV lamp operated at λ = 365 nm. The concentrations of silver ions were 0.1 mmol dm-3 and 1.0 mmol dm-3. Coatings immersed in these solutions were illuminated during 5 min and 30 min. The coating thicknesses, evaluated by ellipsometry, were 118 nm and 147 nm for SG and MS methods, respectively. Atomic force microscopy (AFM) imaging revealed that the surface roughness of TiO2 coating prepared by MS is about 6 times larger as compared to coatings prepared by SG method. The size of AgNPs deposited on SG and MS coatings were in the range of 17-132 nm and 54-103 nm respectively. The photoactivity of AgNPs/TiO2 coatings was determined by the measurement of the decomposition rate of bisphenol A (BPA). The concentration of BPA before and after illumination under UV light (λ = 365 nm) was monitored by high-performance liquid chromatography (HPLC). It was found that AgNPs enhance the photoactivity of the TiO2 coatings.

  3. Effect of film thickness on structural and mechanical properties of AlCrN nanocompoite thin films deposited by reactive DC magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Prakash, Ravi; Kaur, Davinder

    2016-05-01

    In this study, the influence of film thickness on the structural, surface morphology and mechanical properties of Aluminum chromium nitride (AlCrN) thin films has been successfully investigated. The AlCrN thin films were deposited on silicon (100) substrate using dc magnetron reactive co-sputtering at substrate temperature 400° C. The structural, surface morphology and mechanical properties were studied using X-ray diffraction, field-emission scanning electron microscopy and nanoindentation techniques respectively. The thickness of these thin films was controlled by varying the deposition time therefore increase in deposition time led to increase in film thickness. X-ray diffraction pattern of AlCrN thin films with different deposition time shows the presence of (100) and (200) orientations. The crystallite size varies in the range from 12.5 nm to 36.3 nm with the film thickness due to surface energy minimization with the higher film thickness. The hardness pattern of these AlCrN thin films follows Hall-Petch relation. The highest hardness 23.08 Gpa and young modulus 215.31 Gpa were achieved at lowest grain size of 12.5 nm.

  4. Influence of film thickness on the morphological and electrical properties of epitaxial TiC films deposited by reactive magnetron sputtering on MgO substrates

    NASA Astrophysics Data System (ADS)

    Zoita, N. C.; Braic, V.; Danila, M.; Vlaicu, A. M.; Logofatu, C.; Grigorescu, C. E. A.; Braic, M.

    2014-03-01

    Epitaxial TiC films were deposited on MgO (001) by DC magnetron sputtering in a reactive atmosphere of Ar and CH4 at 800 °C. The films elemental composition and chemical bonding was investigated by Auger electron spectroscopy (AES), X-ray photoelectron spectroscopy (XPS) and micro-Raman spectroscopy. The crystallographic structure, investigated by X-ray diffraction, exhibited an increased degree of (001) orientation with the film thickness, with a cube-on-cube epitaxial relationship with the substrate. The films morphology and electrical properties were determined by atomic force microscopy (AFM) and Hall measurements in Van der Pauw geometry. The influences of the film thickness (57-545 nm) on the morphological and electrical properties were investigated. The thinnest film presented the lowest resistivity, 160 μΩ cm, showing an atomically flat surface, while higher values were obtained for the thicker films, explained by their different morphology dominated by low aspect ratio nanoislands/nanocolumns.

  5. Optimization of the optical properties of Er-doped Si-rich SiO 2/SiO 2 multilayers obtained by reactive magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Gourbilleau, F.; Dufour, C.; Madelon, R.; Rizk, R.

    2006-05-01

    The effects of annealing time and of Si nanocluster (Si-nc) size on the coupling rate to Er ions were investigated through studies made on multilayers (MLs) consisting in about 20 periods of Er-doped Si-rich SiO 2/SiO 2. These MLs were deposited by reactive magnetron sputtering at 650 °C and subsequently annealed at 900 °C. A steep increase of the PL emission is observed for short annealing time while a trend of some saturation occurs for longer treatment time. Besides, the Er lifetime continuously increases with the annealing time. For Si-rich layer thickness or Si-nc larger than about 5 nm, the rate of energy transfer is lowered because of the weak confinement of carriers and the loss of resonant excitation of Er through the upper levels (second, third, etc.). The latter is liable to prevent the energy back transfer process, while the weak confinement reduces strongly the probability of no phonon radiative recombination that governs the transfer excitation rate from Si-nc to Er ions.

  6. Effect of annealing treatment on the photocatalytic activity of TiO2 thin films deposited by dc reactive magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Arias, L. M. Franco; Arias Duran, A.; Cardona, D.; Camps, E.; Gómez, M. E.; Zambrano, G.

    2015-07-01

    Titanium dioxide (TiO2) thin films have been deposited by DC reactive magnetron sputtering on silicon and quartz substrates with different Ar/O2 ratios in the gas mixture. Substrate temperature was kept constant at 400 °C during the deposition process, and the TiO2 thin films were later annealed at 700 °C for 3 h. The effect of the Ar/O2 ratio in the gas flow and the annealing treatment on the phase composition, deposition rate, crystallinity, surface morphology and the resulting photocatalytic properties were investigated. For photocatalytic measurements, the variation of the concentration of the methylene blue (MB) dye under UV irradiation was followed by a change in the intensity of the characteristic MB band in the UV- Vis transmittance spectra. We report here that the as-grown TiO2 films showed only the anatase phase, whereas after annealing, the samples exhibited both the anatase and rutile phases in proportions that varied with the Ar/O2 ratio in the mixture of gases used during growth. In particular, the annealed TiO2 thin film deposited at a 50/50 ratio of Ar/O2, composed of both anatase (80%) and rutile phases (20%), exhibited the highest photocatalytic activity (30% of MB degradation) compared with the samples without annealing and composed of only the anatase phase.

  7. Effects of silicon content on the structure and mechanical properties of (AlCrTaTiZr)-Six-N coatings by reactive RF magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Cheng, Keng-Hao; Tsai, Che-Wei; Lin, Su-Jien; Yeh, Jien-Wei

    2011-05-01

    Multi-component (AlCrTaTiZr)-Six-N films were deposited on silicon wafers by reactive RF magnetron co-sputtering. The effect of silicon content on the structure, morphology and mechanical properties of the nitride films was investigated. Nitride films with lower silicon content remained as a simple NaCl-type face-centred cubic (FCC) structure. As the silicon content reached 7.9 at%, thermodynamically driven phase separation occurred, leading to a nanocomposite structure consisting of an FCC solid-solution nitride and an amorphous SiNx phase. These nitride films exhibited a high hardness of 34 GPa and remained at a constant level up to 7.9 at% Si. The reduced hardness at a silicon content of 10.2 at% was attributed to the appreciable amounts of softer amorphous segregation. The silicon incorporation significantly improved the oxidation resistance of (AlCrTaTiZr)N films. The film containing 7.9 at% Si annealed at 1000 °C for 2 h in air only had a 330 nm-thick oxide layer. The optimum Si content is 7.9 at% since it gives the best combination of hardness and oxidation resistance.

  8. Structure Evolution and Electric Properties of TaN Films Deposited on Al2O3-BASED Ceramic and Glass Substrates by Magnetron Reactive Sputtering

    NASA Astrophysics Data System (ADS)

    Zhou, Yan Ming; Ma, Yang Zhao; Xie, Zhong; He, Ming Zhi

    2014-03-01

    Structure evolution and electric properties of tantalum nitride (TaN) films deposited on Al2O3-based ceramic and glass substrates by magnetron reactive sputtering were carried out as a function of the N2-to-Ar flow ratio. The TaN thin films on Al2O3-based ceramic substrates grow with micronclusters composed of numerous nanocrystallites, contains from single-phase of Ta2N grains to TaN, and exhibits high defect density, sheet resistance and negative TCR as the N2-to-Ar flow ratio continuously increases. However, the films on the glass substrates grow in the way of sandwich close-stack, contains from single-phase of Ta2N grains to TaN and Ta3N5 phases with the increase of N2-to-Ar flow ratio. These results indicate that the N2-to-Ar flow ratio and surface characteristic difference of substrates play a dominant effect on the structure and composition of the TaN films, resulting in different electrical properties for the films on Al2O3-based ceramic and the samples on glass substrates.

  9. Influence of absolute argon and oxygen flow values at a constant ratio on the growth of Zn/ZnO nanostructures obtained by DC reactive magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Masłyk, M.; Borysiewicz, M. A.; Wzorek, M.; Wojciechowski, T.; Kwoka, M.; Kamińska, E.

    2016-12-01

    In the present work we analyze the growth mechanism of Zn/ZnO nanostructured thin films obtained by DC reactive magnetron sputtering with variable absolute gas flow values. Zn target was sputtered at 80 W DC power with variable absolute Ar:O2 flow values at a set ratio, in sccm: 3:0.3, 6:0.6, 8:0.8, 10:1, 15:1.5, 20:2 and 30:3. We obtained unique Zn/ZnO nanoflowers with morphology and properties changing as a function of gas flow values from dendritic/nanopetal structures for low flow to dense porous films for high flow. Zn core/ZnO shell composition results from surface oxidation of Zn crystallites to 4 nm thick ZnO after exposure to atmospheric air that causes an increase in resistivity especially for denser, more porous films. Taking into account that the plasma properties measures using the Langmuir probe and optical emission spectroscopy remain constant as a function of gas flow values, we put forward that the structural evolution of films is influenced by oxygen incorporating into the film surface acting as an inhibitor - incorporating into the films and decreasing crystallite sizes and amorphizing the film structure.

  10. Synthesis and properties of CS x F y thin films deposited by reactive magnetron sputtering in an Ar/SF6 discharge.

    PubMed

    Lai, Chung-Chuan; Goyenola, Cecilia; Broitman, Esteban; Näslund, Lars-Åke; Högberg, Hans; Hultman, Lars; Gueorguiev, Gueorgui K; Rosen, Johanna

    2017-05-17

    A theoretical and experimental study on the growth and properties of a ternary carbon-based material, CS x F y , synthesized from SF6 and C as primary precursors is reported. The synthetic growth concept was applied to model the possible species resulting from the fragmentation of SF6 molecules and the recombination of S-F fragments with atomic C. The possible species were further evaluated for their contribution to the film growth. Corresponding solid CS x F y thin films were deposited by reactive direct current magnetron sputtering from a C target in a mixed Ar/SF6 discharge with different SF6 partial pressures ([Formula: see text]). Properties of the films were determined by x-ray photoelectron spectroscopy, x-ray reflectivity, and nanoindentation. A reduced mass density in the CS x F y films is predicted due to incorporation of precursor species with a more pronounced steric effect, which also agrees with the low density values observed for the films. Increased [Formula: see text] leads to decreasing deposition rate and increasing density, as explained by enhanced fluorination and etching on the deposited surface by a larger concentration of F/F2 species during the growth, as supported by an increment of the F relative content in the films. Mechanical properties indicating superelasticity were obtained from the film with lowest F content, implying a fullerene-like structure in CS x F y compounds.

  11. Exclusive examples of high-performance thin-film optical filters for fluorescence spectroscopy made by plasma-assisted reactive magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Lappschies, M.; Schallenberg, U.; Jakobs, S.

    2011-09-01

    For more than four decades band-pass filters are important components of microscopes used for the fluorescence spectroscopy. During all the time this special field of application has been one of the main drivers for research and development in thin-film optics, particularly for the thin-film design software and the coating technology. With a shortwave pass filter, a multi-notch filter, and a classical band-pass filter as examples of such filters provided for the latest generation of fluorescence microscopes we present the state-of-the-art in coating design and technology. Manufacturing these filters is a great challenge because the required spectral characteristics need necessarily multilayers with up to 300 layers and overall thicknesses up to 30 μm. In addition, the designs require also 3 to 5 nm as thinnest layers and all the layers are completely of non-quarterwave type. The filters were manufactured in a rapid-prototyping regime by a Leybold Helios plant using plasma-assisted reactive magnetron sputtering of thin films of different metal oxides. Designed and real spectra are compared and differences are discussed. Measurement results of other optical and non-optical characteristics as film stress, total integrated scattering, and micro roughness are presented.

  12. The influence of substrate temperature on the electrical and optical properties of titanium oxide thin films prepared by d.c. reactive magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Ju, Yongfeng; Wu, Zhiming; Qiu, Yonglong; Li, Lin; Jiang, Yadong

    2010-10-01

    In this investigation, a novel heat-sensitive material titanium oxide (TiOx) thin film was deposited on well cleaned K9 glass substrates by d.c. reactive magnetron sputtering from a metallic titanium target in an Ar + O2 gas mixture. In order to obtain proper TiOx thin films, deposition parameters should be properly controlled. In our system, TiOx thin films were obtained at different substrate temperature while total pressure and oxygen partial pressure were kept at 1 Pa and 0.6 Pa, d.c. power of 100 W, and the deposition time was adjusted in order to deposit thin films with a constant thickness close to 200 nm. The crystalline structure was characterized by X-ray diffraction (XRD) analysis and the results show that all the deposited films have an amorphous structure. In this paper, we have mainly investigated the dependence of electrical and optical properties of the reactively sputtered TiOx thin films on the different substrate temperature during the sputtering process, i.e., as the K9 glass substrate temperature increases from 100 °C to 250°C, the sheet resistance Rs of TiOx thin films is ranged from 305 kΩ/square to 36 kΩ/square, temperature coefficient of resistance (TCR) value up to -2.12 %/K is obtained, optical band gap decreases from 3.34 eV to 3.28 eV. Through the analysis and discussion of the above experimental data, we could obtain the conclusion that the variation in substrate temperature during the sputtering deposition plays a considerable important role in the electrical and optical properties of all the deposited films.

  13. Polyester fabric coated with Ag/ZnO composite film by magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Yuan, Xiaohong; Xu, Wenzheng; Huang, Fenglin; Chen, Dongsheng; Wei, Qufu

    2016-12-01

    Ag/ZnO composite film was successfully deposited on polyester fabric by using direct current (DC) magnetron sputtering and radio frequency (RF) magnetron reaction sputtering techniques with pure silver (Ag) and zinc (Zn) targets. X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) were used to examine the deposited film on the fabric. It was found that the zinc film coated on Ag film before RF reactive sputtering could protect the silver film from oxidation. Anti-ultraviolet property and antistatic property of the coated samples using different magnetron sputtering methods were also investigated. The experimental results showed that Ag film was oxidized into in Ag2O film in high vacuum oxygen environment. The deposition of Zn film on the surface of the fabric coated with Ag film before RF reactive sputtering, could successfully obtained Ag/ZnO composite film, and also generated structural color on the polyester fabric.

  14. PIC simulation of reactive radio-frequency plasma

    NASA Astrophysics Data System (ADS)

    Matthias, Paul; Kahnfeld, Daniel; Lueskow, Karl; Bandelow, Gunnar; Schneider, Ralf; Kemnitz, Stefan; Duras, Julia

    2016-10-01

    Reactive plasmas are important for industrial applications. For sputter processes and plasma etching especially asymmetric capacitively coupled plasmas with a radio-frequency modulated voltage are used. The latest experimental results show an unexpected high-energy peak of negative ions at the grounded anode, depending on the cathode material. Here the Particle-in-Cell (PIC) method was used to simulate this experiment. The main mechanism for the effect is identified as the production of negative ions near the surface of the cathode. In a one dimensional simulation the negative ions are trapped inside the plasma because of the symmetric potential. Thus it was shown that these high-energy peaks of negative ions at the anode only appear in asymmetric discharges, due to the self-bias voltage. To reproduce the asymmetry a two dimensional model will be used in the future. German Space Agency DLR Project 50 RS 1510.

  15. Electric and pyroelectric properties of AlN thin films deposited by reactive magnetron sputtering on Si substrate

    NASA Astrophysics Data System (ADS)

    Stan, G. E.; Botea, M.; Boni, G. A.; Pintilie, I.; Pintilie, L.

    2015-10-01

    Electric and pyroelectric properties of AlN layers deposited on Si substrates with different resistivities were investigated. The dielectric constant was found to be around 12, while the conductance determined from dc current measurements was found to be in the 10-9 to 10-10 S range. The pyroelectric measurements were performed in voltage mode using two types of IR sources: a laser diode with 800 nm wavelength and a black body at 700 °C. A peculiar behavior was observed for the signal recorded when the laser diode was used as IR source. It was found that the Si substrate is introducing a signal component, due to the photogenerated carriers, which is adding to the pyroelectric signal generated by the AlN layer. This component is strongly dependent on the resistivity of the Si substrate. For strongly doped Si (Si++) the signal generated into the substrate represents only 10% of the recorded pyroelectric voltage. For electronic grade Si the signal generated into the substrate is about 100 times larger than the pyroelectric signal generated in the AlN layer. This effect can be used as an optical amplification of the pyroelectric signal. The frequency dependence observed for the pyroelectric signal recorded when the black body is used as IR source is typical for a pyroelectric detector. A value as large as 12.4 μC m-2 K-1 was obtained for the pyroelectric coefficient using for estimation the constant signal at low modulation frequencies of the IR beam. However, the value of the pyroelectric coefficient is strongly affected by the electrical conductance of the AlN layer. As the conductance is frequency dependent it results that the value of the pyroelectric coefficient is frequency dependent, the value from above being valid only for very small frequencies of the temperature variation. It was also found that the electric and pyroelectric properties are dependent on the crystalline quality of the AlN layer.

  16. Potential for reactive pulsed-dc magnetron sputtering of nanocomposite VO{sub x} microbolometer thin films

    SciTech Connect

    Jin, Yao O. Ozcelik, Adem; Horn, Mark W.; Jackson, Thomas N.

    2014-11-01

    Vanadium oxide (VO{sub x}) thin films were deposited by reactive pulsed-dc sputtering a metallic vanadium target in argon/oxygen mixtures with substrate bias. Hysteretic oxidation of the vanadium target surface was assessed by measuring the average cathode current during deposition. Nonuniform oxidization of the target surface was analyzed by Raman spectroscopy. The VO{sub x} film deposition rate, resistivity, and temperature coefficient of resistance were correlated to oxygen to argon ratio, processing pressure, target-to-substrate distance, and oxygen inlet positions. To deposit VO{sub x} in the resistivity range of 0.1–10 Ω-cm with good uniformity and process control, lower processing pressure, larger target-to-substrate distance, and oxygen inlet near the substrate are useful.

  17. High rate reactive magnetron sputter deposition of Al-doped ZnO with unipolar pulsing and impedance control system

    SciTech Connect

    Nishi, Yasutaka; Hirohata, Kento; Tsukamoto, Naoki; Sato, Yasushi; Oka, Nobuto; Shigesato, Yuzo

    2010-07-15

    Al-doped ZnO (AZO) films were deposited on quartz glass substrates, unheated and heated to 200 deg. C, using reactive sputtering with a special feedback system of discharge impedance combined with midfrequency pulsing. A planar Zn-Al alloy target was connected to the switching unit, which was operated in a unipolar pulse mode. The oxidation of the target surface was precisely controlled by a feedback system for the entire O{sub 2} flow ratio including ''the transition region''. The deposition rate was about 10-20 times higher than that for films deposited by conventional sputtering using an oxide target. A deposition rate of AZO films of 390 nm/min with a resistivity of 3.8x10{sup -4} {Omega} cm and a transmittance in the visible region of 85% was obtained when the films were deposited on glass substrates heated to 200 deg. C with a discharge power of 4 kW.

  18. Photocatalytic property of titanium dioxide thin films deposited by radio frequency magnetron sputtering in argon and water vapour plasma

    NASA Astrophysics Data System (ADS)

    Sirghi, L.; Hatanaka, Y.; Sakaguchi, K.

    2015-10-01

    The present work is investigating the photocatalytic activity of TiO2 thin films deposited by radiofrequency magnetron sputtering of a pure TiO2 target in Ar and Ar/H2O (pressure ratio 40/3) plasmas. Optical absorption, structure, surface morphology and chemical structure of the deposited films were comparatively studied. The films were amorphous and included a large amount of hydroxyl groups (about 5% of oxygen atoms were bounded to hydrogen) irrespective of the intentional content of water in the deposition chamber. Incorporation of hydroxyl groups in the film deposited in pure Ar plasma is explained as contamination of the working gas with water molecules desorbed by plasma from the deposition chamber walls. However, intentional input of water vapour into the discharge chamber decreased the deposition speed and roughness of the deposited films. The good photocatalytic activity of the deposited films could be attributed hydroxyl groups in their structures.

  19. Morphology and structure evolution of Cu(In,Ga)S{sub 2} films deposited by reactive magnetron co-sputtering with electron cyclotron resonance plasma assistance

    SciTech Connect

    Nie, Man Ellmer, Klaus

    2014-02-28

    Cu(In,Ga)S{sub 2} (CIGS) films were deposited on Mo coated soda lime glass substrates using an electron cyclotron resonance plasma enhanced one-step reactive magnetron co-sputtering process (ECR-RMS). The crystalline quality and the morphology of the Cu(In,Ga)S{sub 2} films were investigated by X-ray diffraction, atomic force microscopy, scanning electron microscopy, and X-ray fluorescence. We also compared these CIGS films with films previously prepared without ECR assistance and find that the crystallinity of the CIGS films is correlated with the roughness evolution during deposition. Atomic force microscopy was used to measure the surface topography and to derive one-dimensional power spectral densities (1DPSD). All 1DPSD spectra of CIGS films exhibit no characteristic peak which is typical for the scaling of a self-affine surface. The growth exponent β, characterizing the roughness R{sub q} evolution during the film growth as R{sub q} ∼ d{sup β}, changes with film thickness. The root-mean-square roughness at low temperatures increases only slightly with a growth exponent β = 0.013 in the initial growth stage, while R{sub q} increases with a much higher exponent β = 0.584 when the film thickness is larger than about 270 nm. Additionally, we found that the H{sub 2}S content of the sputtering atmosphere and the Cu- to-(In + Ga) ratio has a strong influence of the morphology of the CIGS films in this one-step ECR-RMS process.

  20. Effect of N doping on hole density of Cu2O:N films prepared by the reactive magnetron sputtering method

    NASA Astrophysics Data System (ADS)

    Li, B. B.; Lin, L.; Shen, H. L.; Boafo, F. E.; Chen, Z. F.; Liu, B.; Zhang, R.

    2012-05-01

    N-doped Cu2O thin films have been deposited on glass substrate by reactive magnetron sputtering method under various N2/O2 flow ratios from 0 to 1.0. The structural and electronic properties of Cu2O:N films were investigated by X-ray diffraction (XRD), four-point probe and Hall effect measurements. XRD pattern showed that crystalline structures of all the samples retained single phase of Cu2O with the increase of N2/O2 flow ratio from 0 to 1.0. However, the crystalline quality of Cu2O:N films reduced with the increase of the N2/O2 flow ratio. The phenomenon of peak shift of Cu2O(1 1 1) implied that N atoms have been doped into Cu2O film. The square resistance of Cu2O:N films linearly decreased from 28.1 to 1.5 (104 Ω/☐) with the increase of N2/O2 flow ratio from 0.2 to 0.6 initially, and then it changed slowly with the increase of N2/O2 flow ratio from 0.8 to 1.0. Hole density of Cu2O:N films with various N2/O2 flow ratios from 0 to 0.6 was measured using the Van der Pauw method. All the samples are p-type, and the hole density of Cu2O:N films was enhanced from 1.2 × 1016 cm-3 to 3.1 × 1019 cm-3 with the increase of N2/O2 flow ratio from 0 to 0.6. The experimental results demonstrated that N doping was an effective method to enhance hole density of p-type Cu2O film.

  1. Low-loss interference filter arrays made by plasma-assisted reactive magnetron sputtering (PARMS) for high-performance multispectral imaging

    NASA Astrophysics Data System (ADS)

    Broßmann, Jan; Best, Thorsten; Bauer, Thomas; Jakobs, Stefan; Eisenhammer, Thomas

    2016-10-01

    Optical remote sensing of the earth from air and space typically utilizes several channels in the visible and near infrared spectrum. Thin-film optical interference filters, mostly of narrow bandpass type, are applied to select these channels. The filters are arranged in filter wheels, arrays of discrete stripe filters mounted in frames, or patterned arrays on a monolithic substrate. Such multi-channel filter assemblies can be mounted close to the detector, which allows a compact and lightweight camera design. Recent progress in image resolution and sensor sensitivity requires improvements of the optical filter performance. Higher demands placed on blocking in the UV and NIR and in between the spectral channels, in-band transmission and filter edge steepness as well as scattering lead to more complex filter coatings with thicknesses in the range of 10 - 25μm. Technological limits of the conventionally used ion-assisted evaporation process (IAD) can be overcome only by more precise and higher-energetic coating technologies like plasma-assisted reactive magnetron sputtering (PARMS) in combination with optical broadband monitoring. Optics Balzers has developed a photolithographic patterning process for coating thicknesses up to 15μm that is fully compatible with the advanced PARMS coating technology. This provides the possibility of depositing multiple complex high-performance filters on a monolithic substrate. We present an overview of the performance of recently developed filters with improved spectral performance designed for both monolithic filter-arrays and stripe filters mounted in frames. The pros and cons as well as the resulting limits of the filter designs for both configurations are discussed.

  2. Microstructure and chemical wet etching characteristics of AlN films deposited by ac reactive magnetron sputtering

    SciTech Connect

    Tanner, S. M.; Felmetsger, V. V.

    2010-01-15

    The influence of the surface morphology of a molybdenum underlayer on the crystallinity and etchability of reactively sputtered c-axis oriented aluminum nitride thin films was investigated. Atomic force microscopy, scanning electron microscopy, transmission electron microscopy, high resolution x-ray diffraction, and defect selective chemical etching were used to characterize the microstructure of the Mo and AlN films. 1000 nm thick films of AlN with a full width at half maximum (FWHM) of the x-ray rocking curve ranging from 1.1 deg. to 1.9 deg. were deposited on 300 nm thick Mo underlayers with a FWHM of around 1.5 deg. The Ar pressure during the Mo deposition had a critical effect on the Mo film surface morphology, affecting the structure of the subsequently deposited AlN films and, hence, their wet etching characteristics. AlN films deposited on Mo sputtered at a relatively high pressure could not be etched completely, while AlN films deposited on low pressure Mo etched more easily. Postdeposition etching of the Mo surface in Ar rf discharge prior to deposition of the AlN film was found to influence the formation of AlN residuals that were difficult to etch. Optimal rf plasma etching conditions were found, which minimized the formation of these residuals.

  3. [Study of luminescence properties of nano-size ZnO embedded in SiO2 layer grown by radio-frequency magnetron sputtering].

    PubMed

    Shang, Hong-kai; Zhang, Xi-qing; Yao, Zhi-gang; Teng, Xiao-ying; Wang, Yong-sheng; Huang, Shi-hua

    2006-03-01

    Nano-size ZnO embedded in SiO2 layers were grown by radio-frequency magnetron sputtering. Absorption spectra and PL spectra were employed to study the optical character of the samples at room temperature. Absorption spectra blue-shifted when the size of nano-meter ZnO decreased, which indicated that quantum size effect became stronger with decreasing the size of ZnO. PL spectra show two peaks at about 387 and 441 nm, respectively. It was concluded that the UV emission originates from the radiative recombination of free-exciton, and the blue emission is due to the electron transition from donor levels of oxygen vacancies to the top of valence band. The origin of the two peaks is demonstrated by time-resolved spectra and luminescence decay curve.

  4. CROSS-DISCIPLINARY PHYSICS AND RELATED AREAS OF SCIENCE AND TECHNOLOGY: Surface oxidation of vanadium dioxide films prepared by radio frequency magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Wang, Xue-Jin; Liang, Chun-Jun; Guan, Kang-Ping; Li, De-Hua; Nie, Yu-Xin; Zhu, Shi-Oiu; Huang, Feng; Zhang, Wei-Wei; Cheng, Zheng-Wei

    2008-09-01

    This paper reports that the thermochromic vanadium dioxide films were deposited on various transparent substrates by radio frequency magnetron sputtering, and then aged under circumstance for years. Samples were characterized with several different techniques such as x-ray diffraction, x-ray photoelectron spectroscopy, and Raman, when they were fresh from sputter chamber and aged after years, respectively, in order to determine their structure and composition. It finds that a small amount of sodium occurred on the surface of vanadium dioxide films, which was probably due to sodium ion diffusion from soda-lime glass when sputtering was performed at high substrate temperature. It also finds that aging for years significantly affected the nonstoichiometry of vanadium dioxide films, thus inducing much change in Raman modes.

  5. Heteroepitaxial growth of Cu{sub 2}ZnSnS{sub 4} thin film on sapphire substrate by radio frequency magnetron sputtering

    SciTech Connect

    Song, Ning E-mail: n.song@student.unsw.edu.au; Huang, Yidan; Li, Wei; Huang, Shujuan; Hao, Xiaojing E-mail: n.song@student.unsw.edu.au; Wang, Yu; Hu, Yicong

    2014-03-03

    The heteroepitaxy of tetragonal Cu2ZnSnS4 (CZTS) thin films on hexagonal sapphire (0001) single crystal substrates is successfully obtained by radio frequency magnetron sputtering. The sputtered CZTS film has a mirror-like smooth surface with a root mean square roughness of about 5.44 nm. X-ray θ-2θ scans confirm that CZTS film is (112) oriented on sapphire with an out of plane arrangement of CZTS (112) ‖ sapphire (0001). X-ray Phi scan further illustrates an in plane ordering of CZTS [201{sup ¯}] ‖ sapphire [21{sup ¯}1{sup ¯}0]. The high resolution transmission electron microscopy image of the interface region clearly shows that the CZTS thin film epitaxially grows on the sapphire (0001) substrate. The band gap of the film is found to be approximately 1.51 eV.

  6. Structural and magnetic properties of NiZn-ferrite thin films prepared by radio frequency magnetron sputtering

    SciTech Connect

    Liu Yingli; Li Yuanxun; Zhang Huaiwu; Chen Daming; Mu Chunhong

    2011-04-01

    Polycrystalline NiZn-ferrite thin films were deposited on Si(100) substrate by rf magnetron sputtering, using targets with a nominal composition of Ni{sub 0.5}Zn{sub 0.5}Fe{sub 2}O{sub 4}. The effects of substrate condition, sputtering pressure, and postannealing on the structure and magnetic properties of thin films have been investigated. Our results show that the preferred orientation of the NiZn spinel film changed from (311) to (400) with increasing the Ar pressure from 0.8 to 1.6 Pa, meanwhile, the grain size also increased. Atomic force microscopy analysis indicates that perfect surface morphology of the film can be obtained at a relatively lower sputtering pressure of 1.0 Pa. The relative percentage of residual oxygen increases significantly on a condition of lower sputtering pressure, and plays an important role in film structure due to the strong molecular adsorption tendency of oxygen on the film surface during the deposition process. A thin film with a typical thickness of 1 {mu}m, a saturation magnetization of 150 emu/cm{sup 3}, and a coercivity of 8.8 kA/m has been obtained after annealing at 800 deg. C, which has the potential application in magnetic integrated circuits.

  7. Deuterium Retention in the Co-Deposition Carbon Layers Deposited by Radio-Frequency Magnetron Sputtering in D2 Atmosphere

    NASA Astrophysics Data System (ADS)

    Zhang, Wei-Yuan; Shi, Li-Qun; Zhang, Bin; Hu, Jian-Sheng

    2014-05-01

    Carbon is deposited on C and Si substrates by rf magnetron plasma sputtering in a D2 atmosphere. The deposited layers are examined with ion beam analysis and thermal desorption spectroscopy (TDS). The growth rates of the layers deposited on Si decrease with increasing substrate temperature, while increase significantly with the increase of D2 pressure. Meanwhile, the deuterium concentrations in the layers deposited on the Si substrates decrease from 30% to 2% and from 31% to 1% on the C substrates, respectively, when the substrate temperature varies from 350K to 900 K. Similarly, the D concentration in the layer on the Si substrates increases from 3.4% to 47%, and from 8% to 35% on the C substrates when the D2 pressure increases from 0.3Pa to 8.0Pa. D desorption characterized by TDS is mainly in the forms of D2, HD, HDO, CD4, and C2D4, and a similar release peak occurs at 645 K. The release peak of D2 molecules at 960K can be attributed to the escaped gas from the thin co-deposited deuterium-rich carbon layer in the form of C-D bonding.

  8. Submicrometer Hollow Bioglass Cones Deposited by Radio Frequency Magnetron Sputtering: Formation Mechanism, Properties, and Prospective Biomedical Applications.

    PubMed

    Popa, A C; Stan, G E; Besleaga, C; Ion, L; Maraloiu, V A; Tulyaganov, D U; Ferreira, J M F

    2016-02-01

    This work reports on the unprecedented magnetron sputtering deposition of submicrometric hollow cones of bioactive glass at low temperature in the absence of any template or catalyst. The influence of sputtering conditions on the formation and development of bioglass cones was studied. It was shown that larger populations of well-developed cones could be achieved by increasing the argon sputtering pressure. A mechanism describing the growth of bioglass hollow cones is presented, offering the links for process control and reproducibility of the cone features. The composition, structure, and morphology of the as-synthesized hollow cones were investigated by energy dispersive spectroscopy (EDS), Fourier transform infrared spectroscopy (FTIR), grazing incidence geometry X-ray diffraction (GIXRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM)-selected area electron diffraction (SAED). The in vitro biological performance, assessed by degradation tests (ISO 10993-14) and cytocompatibility assays (ISO 10993-5) in endothelial cell cultures, was excellent. This allied with resorbability and the unique morphological features make the submicrometer hollow cones interesting candidate material devices for focal transitory permeabilization of the blood-brain barrier in the treatment of carcinoma and neurodegenerative disorders.

  9. Radio frequency magnetron sputtering of Li7La3Zr2O12 thin films for solid-state batteries

    NASA Astrophysics Data System (ADS)

    Lobe, S.; Dellen, C.; Finsterbusch, M.; Gehrke, H.-G.; Sebold, D.; Tsai, C.-L.; Uhlenbruck, S.; Guillon, O.

    2016-03-01

    Thin film batteries based on solid electrolytes having a garnet-structure like Li7La3Zr2O12 (LLZ) are considered as one option for safer batteries with increased power density. In this work we show the deposition of Ta- and Al-substituted LLZ thin films on stainless steel substrates by r.f. magnetron sputtering. The thin films were characterized by XRD, SEM and time-of-flight-secondary ion mass spectrometry (ToF-SIMS) to determine crystal structure, morphology and element distribution. The substrate temperature was identified to be one important parameter for the formation of cubic garnet-structured LLZ thin films. LLZ formation starts at around 650 °C. Single phase cubic thin films were obtained at substrate temperatures of 700 °C and higher. At these temperatures an interlayer is formed. Combination of SEM, ToF-SIMS and XRD indicated that this layer consists of γ-LiAlO2. The combined total ionic conductivity of the γ-LiAlO2 interlayer and the LLZ thin film (perpendicular to the plane) was determined to be 2.0 × 10-9 S cm-1 for the sample deposited at 700 °C. In-plane measurements showed a room temperature conductivity of 1.2 × 10-4 S cm-1 with an activation energy of 0.47 eV for the LLZ thin film.

  10. Low-temperature growth of low friction wear-resistant amorphous carbon nitride thin films by mid-frequency, high power impulse, and direct current magnetron sputtering

    SciTech Connect

    Bakoglidis, Konstantinos D. Schmidt, Susann; Garbrecht, Magnus; Ivanov, Ivan G.; Jensen, Jens; Greczynski, Grzegorz; Hultman, Lars

    2015-09-15

    The potential of different magnetron sputtering techniques for the synthesis of low friction and wear resistant amorphous carbon nitride (a-CN{sub x}) thin films onto temperature-sensitive AISI52100 bearing steel, but also Si(001) substrates was studied. Hence, a substrate temperature of 150 °C was chosen for the film synthesis. The a-CN{sub x} films were deposited using mid-frequency magnetron sputtering (MFMS) with an MF bias voltage, high power impulse magnetron sputtering (HiPIMS) with a synchronized HiPIMS bias voltage, and direct current magnetron sputtering (DCMS) with a DC bias voltage. The films were deposited using a N{sub 2}/Ar flow ratio of 0.16 at the total pressure of 400 mPa. The negative bias voltage, V{sub s}, was varied from 20 to 120 V in each of the three deposition modes. The microstructure of the films was characterized by high-resolution transmission electron microscopy and selected area electron diffraction, while the film morphology was investigated by scanning electron microscopy. All films possessed an amorphous microstructure, while the film morphology changed with the bias voltage. Layers grown applying the lowest substrate bias of 20 V exhibited pronounced intercolumnar porosity, independent of the sputter technique. Voids closed and dense films are formed at V{sub s} ≥ 60 V, V{sub s} ≥ 100 V, and V{sub s} = 120 V for MFMS, DCMS, and HiPIMS, respectively. X-ray photoelectron spectroscopy revealed that the nitrogen-to-carbon ratio, N/C, of the films ranged between 0.2 and 0.24. Elastic recoil detection analysis showed that Ar content varied between 0 and 0.8 at. % and increased as a function of V{sub s} for all deposition techniques. All films exhibited compressive residual stress, σ, which depends on the growth method; HiPIMS produces the least stressed films with values ranging between −0.4 and −1.2 GPa for all V{sub s}, while CN{sub x} films deposited by MFMS showed residual stresses up to −4.2

  11. Influence of vanadium incorporation on the microstructure, mechanical and tribological properties of Nb–V–Si–N films deposited by reactive magnetron sputtering

    SciTech Connect

    Ju, Hongbo; Xu, Junhua

    2015-09-15

    Composite Nb–V–Si–N films with various V contents (3.7–13.2 at.%) were deposited by reactive magnetron sputtering and the effects of V content on the microstructure, mechanical and tribological properties of Nb–V–Si–N films were investigated. The results revealed that a three-phase structure, consisting of face-centered cubic (fcc) Nb–V–Si–N, hexagonal close-packed (hcp) Nb–V–Si–N and amorphous Si{sub 3}N{sub 4}, co-exists in the Nb–V–Si–N films and the cubic phase is dominant. The hardness and critical load (L{sub c}) of Nb–V–Si–N films initially increased gradually and reached a summit, then decreased with the increasing V content in the films and the maximum values were 35 GPa and 9.8 N, respectively, at 6.4 at.% V. The combination of V into Nb–Si–N film led to the fracture toughness linearly increasing from 1.11 MPa·m{sup 1/2} at 3.7 at.% V to 1.67 MPa·m{sup 1/2} at 13.2 at.% V. At room temperature (RT), the average friction coefficient decreased from 0.80 at 3.7 at.% V to 0.55 at 13.2 at.% V for the Nb–V–Si–N films. The wear rate of Nb–V–Si–N films initially decreased and then increased after reaching a minimum value of about 6.35 × 10{sup −} {sup 7} mm{sup 3}/N·mm at 6.4 at.% V. As the rise of testing temperature from 200 °C to 600 °C, the average friction coefficient of Nb–V–Si–N films decreased with the increase of the testing temperature regardless of V content. However, the wear rate gradually increased for all films. The average friction coefficient and wear rate at RT and elevated temperatures were mainly influenced by the vanadium oxides with weakly bonded lattice planes. - Highlight: • Fcc-Nb–V–Si–N, hcp-Nb–V–Si–N and amorphous Si{sub 3}N{sub 4} co-existed in the films. • The amount of Si{sub 3}N{sub 4} decreased with increasing V content in the films. • Hardness of Nb–V–Si–N film (6.4 at.%) reached a maximum value of 35 GPa. • Addition of V led to the

  12. In-situ spectroscopic ellipsometry and structural study of HfO{sub 2} thin films deposited by radio frequency magnetron sputtering

    SciTech Connect

    Cantas, Ayten; Aygun, Gulnur; Basa, Deepak Kumar

    2014-08-28

    We have investigated the reduction of unwanted interfacial SiO{sub 2} layer at HfO{sub 2}/Si interface brought about by the deposition of thin Hf metal buffer layer on Si substrate prior to the deposition of HfO{sub 2} thin films for possible direct contact between HfO{sub 2} thin film and Si substrate, necessary for the future generation devices based on high-κ HfO{sub 2} gate dielectrics. Reactive rf magnetron sputtering system along with the attached in-situ spectroscopic ellipsometry (SE) was used to predeposit Hf metal buffer layer as well as to grow HfO{sub 2} thin films and also to undertake the in-situ characterization of the high-κ HfO{sub 2} thin films deposited on n-type 〈100〉 crystalline silicon substrate. The formation of the unwanted interfacial SiO{sub 2} layer and its reduction due to the predeposited Hf metal buffer layer as well as the depth profiling and also structure of HfO{sub 2} thin films were investigated by in-situ SE, Fourier Transform Infrared spectroscopy, and Grazing Incidence X-ray Diffraction. The study demonstrates that the predeposited Hf metal buffer layer has played a crucial role in eliminating the formation of unwanted interfacial layer and that the deposited high-κ HfO{sub 2} thin films are crystalline although they were deposited at room temperature.

  13. An efficient magnetron transmitter for superconducting accelerators

    DOE PAGES

    Kazakevich, G.; Lebedev, V.; Yakovlev, V.; ...

    2016-09-22

    A concept of a highly-efficient high-power magnetron transmitter allowing wide-band phase and the mid-frequency power control at the frequency of the locking signal is proposed. The proposal is aimed for powering Superconducting RF (SRF) cavities of intensity-frontier accelerators. The transmitter is intended to operate with phase and amplitude control feedback loops allowing suppression of microphonics and beam loading in the SRF cavities. The concept utilizes injectionlocked magnetrons controlled in phase by the locking signal supplied by a feedback system. The injection-locking signal pre-excites the magnetron and allows its operation below the critical voltage. This realizes control of the magnetron powermore » in a wide range by control of the magnetron current. Pre-excitation of the magnetron by the locking signal provides an output power range up to 10 dB. Experimental studies were carried out with 2.45 GHz, 1 kW, CW magnetrons. They demonstrated stable operation of the magnetrons and power control at a low noise level. In conclusion, an analysis of the kinetics of the drifting charge in the drift approximation substantiates the concept and the experimental results.« less

  14. An efficient magnetron transmitter for superconducting accelerators

    NASA Astrophysics Data System (ADS)

    Kazakevich, G.; Lebedev, V.; Yakovlev, V.; Pavlov, V.

    2016-12-01

    A concept of a highly-efficient high-power magnetron transmitter allowing wide-band phase and the mid-frequency power control at the frequency of the locking signal is proposed. The proposal is aimed for powering Superconducting RF (SRF) cavities of intensity-frontier accelerators. The transmitter is intended to operate with phase and amplitude control feedback loops allowing suppression of microphonics and beam loading in the SRF cavities. The concept utilizes injection-locked magnetrons controlled in phase by the locking signal supplied by a feedback system. The injection-locking signal pre-excites the magnetron and allows its operation below the critical voltage in free run. This realizes control of the magnetron power in an extended range (up to 10 dB) by control of the magnetron current. Experimental studies were carried out with 2.45 GHz, 1 kW, CW magnetrons. They demonstrated stable operation of the magnetrons and the required range of power control at a low noise level. An analysis of the kinetics of the drifting charge within the framework of the presented model of phase focusing in magnetrons substantiates the concept and the experimental results.

  15. An efficient magnetron transmitter for superconducting accelerators

    SciTech Connect

    Kazakevich, G.; Lebedev, V.; Yakovlev, V.; Pavlov, V.

    2016-09-22

    A concept of a highly-efficient high-power magnetron transmitter allowing wide-band phase and the mid-frequency power control at the frequency of the locking signal is proposed. The proposal is aimed for powering Superconducting RF (SRF) cavities of intensity-frontier accelerators. The transmitter is intended to operate with phase and amplitude control feedback loops allowing suppression of microphonics and beam loading in the SRF cavities. The concept utilizes injectionlocked magnetrons controlled in phase by the locking signal supplied by a feedback system. The injection-locking signal pre-excites the magnetron and allows its operation below the critical voltage. This realizes control of the magnetron power in a wide range by control of the magnetron current. Pre-excitation of the magnetron by the locking signal provides an output power range up to 10 dB. Experimental studies were carried out with 2.45 GHz, 1 kW, CW magnetrons. They demonstrated stable operation of the magnetrons and power control at a low noise level. In conclusion, an analysis of the kinetics of the drifting charge in the drift approximation substantiates the concept and the experimental results.

  16. Effect of radio-frequency electric power applied to a boron nitride unbalanced magnetron sputter target on the deposition of cubic boron nitride thin film

    NASA Astrophysics Data System (ADS)

    Ko, Ji-Sun; Park, Jong-Keuk; Lee, Wook-Seong; Huh, Joo-Youl; Baik, Young-Joon

    2013-11-01

    Cubic boron nitride (c-BN) films were deposited by an unbalanced magnetron sputtering method. A (100) Si wafer with a nanocrystalline diamond thin film as a surface coating layer or that without it was used as a substrate. The target power was varied from 100 to 400 W. A boron nitride target was used, which was connected to a radio frequency power supply. High frequency power connected to a substrate holder was used for self-biasing. The deposition pressure was 0.27 MPa with a flow of Ar (18 sccm) — N2 (2 sccm) mixed gas. The existence of threshold bias voltages for c-BN formation and resputtering were observed irrespective of target power. The bias voltage window for c-BN formation broadened with increased target power. The deposition rate decreased with enhanced bias voltage and decreased target power. Residual stresses of the films did not vary noticeably with target power within the target power range of c-BN formation. A parameter space for c-BN formation according to the target power and the bias voltage, as two variables, was suggested.

  17. Peer-to-Peer Magnetron Locking

    NASA Astrophysics Data System (ADS)

    Cruz, Edward Jeffrey

    The viability of coherent power combination of multiple high-efficiency, moderate power magnetrons requires a thorough understanding of frequency and phase control. Injection locking of conventional magnetrons, and other types of oscillators, employing a master-to-slave configuration has been studied theoretically and experimentally. This dissertation focuses on the peer-to-peer locking, where each oscillator acts as a master of and slave to all others, between two conventional magnetrons, where the general condition for locking was recently derived. The experiments performed on peer-to-peer locking of two 1-kW magnetrons verify the recently developed theory on the condition under which the two nonlinear oscillators may be locked to a common frequency and relative phase. This condition reduces to Adler's classical locking condition (master-slave) if the coupling is one way. Dependent on the degree of coupling, the frequency of oscillation when locking occurs was found to not necessarily lie between the two magnetrons' free running frequencies. Likewise, when the locking condition was violated, the beat of the spectrum was not necessarily found to be equal to the difference between the free running frequencies. The frequency of oscillation and relative phase between the two magnetrons when locking did occur were found to correspond to one of two solution modes given by the recent theory. The accessibility of the two possible modes is yet to be determined. This work was supported by ONR, AFRL, AFOSR, L-3 Communications Electron Devices Division and Northrop-Grumman Corporation.

  18. Effects of Mg doping content and annealing temperature on the structural properties of Zn1- x Mg x O thin films prepared by radio-frequency magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Du, Wen-han; Yang, Jing-jing; Zhao, Yu; Xiong, Chao

    2017-01-01

    The doping content of Mg plays an important role in the crystalline structure and morphology properties of Zn1- x Mg x O thin films. Here, using radio-frequency magnetron sputtering method, we prepared Zn1- x Mg x O thin films on single crystalline Si(100) substrates with a series of x values. By means of X-ray diffraction (XRD) and scanning electron microscope (SEM), the crystalline structure and morphology of Zn1- x Mg x O thin films with different x values are investigated. The crystalline structure of Zn1- x Mg x O thin film is single phase with x<0.3, while there is phase separation phenomenon with x>0.3, and hexagonal and cubic structures will coexist in Zn1- x Mg x O thin films with higher x values. Especially with lower x values, a shoulder peak of 35.1° appearing in the XRD pattern indicates a double-crystalline structure of Zn1- x Mg x O thin film. The crystalline quality has been improved and the inner stress has been released, after the Zn1- x Mg x O thin films were annealed at 600 °C in vacuum condition.

  19. Characteristics of Gallium-Doped Zinc Oxide Thin-Film Transistors Fabricated at Room Temperature Using Radio Frequency Magnetron Sputtering Method

    NASA Astrophysics Data System (ADS)

    Jeon, Hoonha; Verma, Ved Prakash; Hwang, Sookhyun; Lee, Sooyeon; Park, Chiyoung; Kim, Do-Hyun; Choi, Wonbong; Jeon, Minhyon

    2008-01-01

    In this paper, we present bottom-gate-type Ga-doped zinc oxide (GZO) thin-film transistors (TFTs) using a certain conventional SiO2 gate insulator by applying a radio-frequency (RF) magnetron sputtering method at room temperature. A low gate leakage current was achieved using this conventional SiO2 gate insulator instead of new gate oxide materials. The root mean square (RMS) value of the GZO film surface was found to be 1.65 nm, and the transmittance was higher than 75% in the visible region. The GZO TFTs operated in a depletion mode with a threshold voltage of -3.4 V. A mobility of 0.023 cm2/(V·s), an on/off ratio of 2×103, and a gate voltage swing of 3.3 V/decade were obtained. We successfully demonstrated that the TFT of depletion-mode type can be fabricated using a GZO film that has good surface uniformity, transparency, and electrical characteristics.

  20. Influence of growth temperature on electrical, optical, and plasmonic properties of aluminum:zinc oxide films grown by radio frequency magnetron sputtering

    SciTech Connect

    Dondapati, Hareesh; Santiago, Kevin; Pradhan, A. K.

    2013-10-14

    We have investigated the responsible mechanism for the observation of metallic conductivity at room temperature and metal-semiconductor transition (MST) at lower temperatures for aluminum-doped zinc oxide (AZO) films. AZO films were grown on glass substrates by radio-frequency magnetron sputtering with varying substrate temperatures (T{sub s}). The films were found to be crystalline with the electrical resistivity close to 1.1 × 10{sup −3} Ω cm and transmittance more than 85% in the visible region. The saturated optical band gap of 3.76 eV was observed for the sample grown at T{sub s} of 400 °C, however, a slight decrease in the bandgap was noticed above 400 °C, which can be explained by Burstein–Moss effect. Temperature dependent resistivity measurements of these highly conducting and transparent films showed a MST at ∼110 K. The observed metal-like and metal-semiconductor transitions are explained by taking into account the Mott phase transition and localization effects due to defects. All AZO films demonstrate crossover in permittivity from positive to negative and low loss in the near-infrared region, illustrating its applications for plasmonic metamaterials, including waveguides for near infrared telecommunication region. Based on the results presented in this study, the low electrical resistivity and high optical transmittance of AZO films suggested a possibility for the application in the flexible electronic devices, such as transparent conducting oxide film on LEDs, solar cells, and touch panels.

  1. Comprehensive study of the p-type conductivity formation in radio frequency magnetron sputtered arsenic-doped ZnO film

    SciTech Connect

    Fan, J. C.; Zhu, C. Y.; Yang, B.; Fung, S.; Beling, C. D.; Brauer, G.; Anwand, W.; Grambole, D.; Skorupa, W.; Wong, K. S.; Zhong, Y. C.; Xie, Z.; Ling, C. C.

    2011-05-15

    Arsenic doped ZnO and ZnMgO films were deposited on SiO{sub 2} using radio frequency magnetron sputtering and ZnO-Zn{sub 3}As{sub 2} and ZnO-Zn{sub 3}As{sub 2}-MgO targets, respectively. It was found that thermal activation is required to activate the formation of p-type conductivity. Hall measurements showed that p-type films with a hole concentration of {approx}10{sup 17} cm{sup -3} and mobility of {approx}8 cm{sup 2} V{sup -1} s{sup -1} were obtained at substrate temperatures of 400-500 deg. C The shallow acceptor formation mechanism was investigated using x-ray photoelectron spectroscopy, positron annihilation, low temperature photoluminescence, and nuclear reaction analysis. The authors suggest that the thermal annealing activates the formation of the As{sub Zn}-2V{sub Zn} shallow acceptor complex and removes the compensating hydrogen center.

  2. Influence of growth temperature on electrical, optical, and plasmonic properties of aluminum:zinc oxide films grown by radio frequency magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Dondapati, Hareesh; Santiago, Kevin; Pradhan, A. K.

    2013-10-01

    We have investigated the responsible mechanism for the observation of metallic conductivity at room temperature and metal-semiconductor transition (MST) at lower temperatures for aluminum-doped zinc oxide (AZO) films. AZO films were grown on glass substrates by radio-frequency magnetron sputtering with varying substrate temperatures (Ts). The films were found to be crystalline with the electrical resistivity close to 1.1 × 10-3 Ω cm and transmittance more than 85% in the visible region. The saturated optical band gap of 3.76 eV was observed for the sample grown at Ts of 400 °C, however, a slight decrease in the bandgap was noticed above 400 °C, which can be explained by Burstein-Moss effect. Temperature dependent resistivity measurements of these highly conducting and transparent films showed a MST at ˜110 K. The observed metal-like and metal-semiconductor transitions are explained by taking into account the Mott phase transition and localization effects due to defects. All AZO films demonstrate crossover in permittivity from positive to negative and low loss in the near-infrared region, illustrating its applications for plasmonic metamaterials, including waveguides for near infrared telecommunication region. Based on the results presented in this study, the low electrical resistivity and high optical transmittance of AZO films suggested a possibility for the application in the flexible electronic devices, such as transparent conducting oxide film on LEDs, solar cells, and touch panels.

  3. Enhancement of the mechanical properties of AZ31 magnesium alloy via nanostructured hydroxyapatite thin films fabricated via radio-frequency magnetron sputtering.

    PubMed

    Surmeneva, M A; Tyurin, A I; Mukhametkaliyev, T M; Pirozhkova, T S; Shuvarin, I A; Syrtanov, M S; Surmenev, R A

    2015-06-01

    The structure, composition and morphology of a radio-frequency (RF) magnetron sputter-deposited dense nano-hydroxyapatite (HA) coating that was deposited on the surface of an AZ31 magnesium alloy were characterized using AFM, SEM, EDX and XRD. The results obtained from SEM and XRD experiments revealed that the bias applied during the deposition of the HA coating resulted in a decrease in the grain and crystallite size of the film having a crucial role in enhancing the mechanical properties of the fabricated biocomposites. A maximum hardness of 9.04 GPa was found for the HA coating, which was prepared using a bias of -50 V. The hardness of the HA film deposited on the grounded substrate (GS) was found to be 4.9 GPa. The elastic strain to failure (H/E) and the plastic deformation resistance (H(3)/E(2)) for an indentation depth of 50 nm for the HA coating fabricated at a bias of -50 V was found to increase by ~30% and ~74%, respectively, compared with the coating deposited at the GS holder. The nanoindentation tests demonstrated that all of the HA coatings increased the surface hardness on both the microscale and the nanoscale. Therefore, the results revealed that the films deposited on the surface of the AZ31 magnesium alloy at a negative substrate bias can significantly enhance the wear resistance of this resorbable alloy.

  4. Growth Behavior of Ga-Doped ZnO Thin Films Deposited on Au/SiN/Si(001) Substrates by Radio Frequency Magnetron Sputtering

    NASA Astrophysics Data System (ADS)

    Seo, Seon Hee; Kang, Hyon Chol

    2013-11-01

    This paper reports the growth behavior of Ga-doped ZnO (ZnO:Ga) thin films deposited on Au/SiN/Si(001) substrates by radio-frequency magnetron sputtering. The microstructures of the overgrown ZnO:Ga thin films were investigated by performing X-ray diffraction, scanning electron microcopy, and transmission electron microscopy analyses. It was confirmed that the growth process proceeds through three stages. In the first stage, nano-scale ZnO:Ga islands were grown on the SiN layer, while a fairly continuous flat structure was formed on the Au nanoparticles (NPs). In the second stage of the growth process, ZnO:Ga domains with different growth orientations, depending strongly on the crystalline planes of the host Au NPs, were nucleated. These domains then grew at different rates, resulting in a change in the morphology from the initial shape reflecting that of the Au NPs to a sunflower-type shape. In the final stage, columnar growth with a preferred (0002) orientation along the surface normal direction became dominant.

  5. Low temperature synthesis of radio frequency magnetron sputtered gallium and aluminium co-doped zinc oxide thin films for transparent electrode fabrication

    NASA Astrophysics Data System (ADS)

    Muchuweni, E.; Sathiaraj, T. S.; Nyakotyo, H.

    2016-12-01

    Gallium and aluminium co-doped zinc oxide (GAZO) thin films were prepared on glass substrates at low temperatures by radio frequency (rf) magnetron sputtering and their physical properties were investigated. All films possessed a hexagonal wurtzite crystal structure with a strong growth orientation along the (0 0 2) c-axis. The (0 0 2) peak intensity and mean crystallite size increased with substrate temperature from room temperature (RT) to 75 °C and then decreased at 100 °C, indicating an improvement in crystallinity up to 75 °C and its deterioration at 100 °C. Scanning electron microscopy (SEM) micrographs revealed the strong dependency of surface morphology on substrate temperature and energy dispersive spectroscopy (EDS) confirmed the incorporation of Ga and Al into the ZnO films. All films exhibited excellent transmittances between 85 and 90% in the visible region and their optical band gap increased from 3.22 eV to 3.28 eV with substrate temperature. The Urbach energy decreased from 194 meV to 168 meV with increasing substrate temperature, indicating a decrease in structural disorders which was consistent with X-ray Diffraction (XRD) analysis. Films deposited at 75 °C exhibited the lowest electrical resistivity (2.4 Ωcm) and highest figure of merit (7.5 × 10-5 Ω-1), proving their potential as candidates for transparent electrode fabrication.

  6. Post-growth annealing induced change of conductivity in As-doped ZnO grown by radio frequency magnetron sputtering

    NASA Astrophysics Data System (ADS)

    To, C. K.; Yang, B.; Su, S. C.; Ling, C. C.; Beling, C. D.; Fung, S.

    2011-12-01

    Arsenic-doped ZnO films were fabricated by radio frequency magnetron sputtering method at a relatively low substrate temperature of 200 °C. Post-growth annealing in air was carried out up to a temperature of 1000 °C. The samples were characterized by Hall measurement, positron annihilation spectroscopy (PAS), secondary ion mass spectroscopy (SIMS), and cathodoluminescence (CL). The as-grown sample was of n-type and it converted to p-type material after the 400 °C annealing. The resulting hole concentration was found to increase with annealing temperature and reached a maximum of 6 × 1017 cm-3 at the annealing temperature of 600 °C. The origin of the p-type conductivity was consistent with the AsZn(VZn)2 shallow acceptor model. Further increasing the annealing temperature would decrease the hole concentration of the samples finally converted the sample back to n-type. With evidence, it was suggested that the removal of the p-type conductivity was due to the dissociation of the AsZn(VZn)2 acceptor and the creation of the deep level defect giving rise to the green luminescence.

  7. Influence of Oxygen Gas Ratio on the Properties of Aluminum-Doped Zinc Oxide Films Prepared by Radio Frequency Magnetron Sputtering.

    PubMed

    Kim, Minha; Jang, Yong-Jun; Jung, Ho-Sung; Song, Woochang; Kang, Hyunil; Kim, Eung Kwon; Kim, Donguk; Yi, Junsin; Lee, Jaehyeong

    2016-05-01

    Aluminum-doped zinc oxide (AZO) thin films were deposited on glass and polyimide substrates using radio frequency magnetron sputtering. We investigated the effects of the oxygen gas ratio on the properties of the AZO films for Cu(In,Ga)Se2 thin-film solar cell applications. The structural and optical properties of the AZO thin films were measured using X-ray diffraction (XRD), field emission scanning electron microscope (FE-SEM), and UV-Visible-NIR spectrophotometry. The oxygen gas ratio played a crucial role in controlling the optical as well as electrical properties of the films. When oxygen gas was added into the film, the surface AZO thin films became smoother and the grains were enlarged while the preferred orientation changed from (0 0 2) to (1 0 0) plane direction of the hexagonal phase. An improvement in the transmittance of the AZO thin films was achieved with the addition of 2.5-% oxygen gas. The electrical resistivity was highly increased even for a small amount of the oxygen gas addition.

  8. Biaxial stress and optoelectronic properties of Al-doped ZnO thin films deposited on flexible substrates by radio frequency magnetron sputtering.

    PubMed

    Chen, Hsi-Chao; Cheng, Po-Wei; Huang, Kuo-Ting

    2017-02-01

    Transparent conductive Al-doped ZnO (AZO) thin films were deposited on polyethylene terephthalate (PET) and polycarbonate (PC) substrates using radio frequency (RF) magnetron sputtering. The biaxial stress was measured with a double beam shadow moiré interferometer, and x-ray diffraction (XRD) was used to investigate the crystal orientation of ZnO. The substrate temperature was varied from room temperature to 150°C in steps of 25°C. The experimental results showed that the residual and shearing stresses increased with the increase in substrate temperature. The residual stress can be separated into principle and shearing stresses by Mohr's circle rule, and the shearing stress (tensile stress) was different from the compressive stress of the residual stress. However, the optimal substrate temperatures for PET and PC were 75°C and 100°C, and the shearing stresses were 424.82 and 543.68 MPa, respectively. AZO/PET and AZO/PC thin films cracked at substrate temperatures of 75°C and 100°C, respectively. AZO/PET thin film at a substrate temperature of 100°C had a resistivity low to the order of 10-3  Ω-cm.

  9. Thick c-BN films deposited by radio frequency magnetron sputtering in argon/nitrogen gas mixture with additional hydrogen gas

    NASA Astrophysics Data System (ADS)

    Zhao, Yan; Gao, Wei; Xu, Bo; Li, Ying-Ai; Li, Hong-Dong; Gu, Guang-Rui; Yin, Hong

    2016-10-01

    The excellent physical and chemical properties of cubic boron nitride (c-BN) film make it a promising candidate for various industry applications. However, the c-BN film thickness restricts its practical applications in many cases. Thus, it is indispensable to develop an economic, simple and environment-friend way to synthesize high-quality thick, stable c-BN films. High-cubic-content BN films are prepared on silicon (100) substrates by radio frequency (RF) magnetron sputtering from an h-BN target at low substrate temperature. Adhesions of the c-BN films are greatly improved by adding hydrogen to the argon/nitrogen gas mixture, allowing the deposition of a film up to 5-μm thick. The compositions and the microstructure morphologies of the c-BN films grown at different substrate temperatures are systematically investigated with respect to the ratio of H2 gas content to total working gas. In addition, a primary mechanism for the deposition of thick c-BN film is proposed. Project supported by the National Natural Science Foundation of China (Grant Nos. 51572105, 61504046, and 51272224), the Scientific Research Foundation for the Returned Overseas Chinese Scholars, State Education Ministry, China, the Development and Reform Commission of Jilin Province, China (Grant No. 2015Y050), and the Scientific Research Foundation for the Returned Overseas of Jilin Province, China.

  10. Morphology and structure evolution of tin-doped indium oxide thin films deposited by radio-frequency magnetron sputtering: The role of the sputtering atmosphere

    SciTech Connect

    Nie, Man Mete, Tayfun; Ellmer, Klaus

    2014-04-21

    The microstructure and morphology evolution of tin-doped indium oxide (ITO) thin films deposited by radio-frequency magnetron sputtering in different sputtering atmospheres were investigated by X-ray diffraction, X-ray reflectivity, and atomic force microscopy. The surface roughness w increases with increasing film thickness d{sub f}, and exhibits a power law behavior w ∼ d{sub f}{sup β}. The roughness decreases with increasing O{sub 2} flow, while it increases with increasing H{sub 2} flow. The growth exponent β is found to be 0.35, 0.75, and 0.98 for depositions in Ar/10%O{sub 2}, pure Ar, and Ar/10%H{sub 2} atmospheres, respectively. The correlation length ξ increases with film thickness also with a power law according to ξ ∼ d{sub f}{sup z} with exponents z = 0.36, 0.44, and 0.57 for these three different gas atmospheres, respectively. A combination of local and non-local growth modes in 2 + 1 dimensions is discussed for the ITO growth in this work.

  11. Post-growth annealing induced change of conductivity in As-doped ZnO grown by radio frequency magnetron sputtering

    SciTech Connect

    To, C. K.; Yang, B.; Su, S. C.; Ling, C. C.; Beling, C. D.; Fung, S.

    2011-12-01

    Arsenic-doped ZnO films were fabricated by radio frequency magnetron sputtering method at a relatively low substrate temperature of 200 deg. C. Post-growth annealing in air was carried out up to a temperature of 1000 deg. C. The samples were characterized by Hall measurement, positron annihilation spectroscopy (PAS), secondary ion mass spectroscopy (SIMS), and cathodoluminescence (CL). The as-grown sample was of n-type and it converted to p-type material after the 400 deg. C annealing. The resulting hole concentration was found to increase with annealing temperature and reached a maximum of 6 x 10{sup 17} cm{sup -3} at the annealing temperature of 600 deg. C. The origin of the p-type conductivity was consistent with the As{sub Zn}(V{sub Zn}){sub 2} shallow acceptor model. Further increasing the annealing temperature would decrease the hole concentration of the samples finally converted the sample back to n-type. With evidence, it was suggested that the removal of the p-type conductivity was due to the dissociation of the As{sub Zn}(V{sub Zn}){sub 2} acceptor and the creation of the deep level defect giving rise to the green luminescence.

  12. Change of scattering mechanism and annealing out of defects on Ga-doped ZnO films deposited by radio-frequency magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Nulhakim, Lukman; Makino, Hisao

    2016-06-01

    This study examines the change of carrier scattering mechanism and defects states in Ga-doped ZnO (GZO) thin films deposited by radio-frequency magnetron sputtering as a function of the substrate temperature (Ts) during deposition. The GZO films deposited at room temperature exhibited a high defect density that resulted in a lower carrier concentration, lower Hall mobility, and optical absorption in visible wavelength range. Such defects were created by ion bombardment and were eliminated by increasing the Ts. The defects related to the optical absorption disappeared at a Ts of 125 °C. The defects responsible for the suppression of the carrier concentration gradually decreased with increasing Ts up to 200 °C. As a result, the carrier concentration and in-grain carrier mobility gradually increased. The Hall mobility was also influenced by film structural properties depending on the Ts. In addition to the c-axis preferred orientation, other oriented grains such as the (10 1 ¯ 1 ) plane parallel to the substrate surface appeared below 150 °C. This orientation of the (10 1 ¯ 1 ) plane significantly reduced the Hall mobility via grain boundary scattering. The films deposited at a Ts higher than 175 °C exhibited perfect c-axis orientation and grain boundary scattering was thus negligible in these films. The appearance of the 10 1 ¯ 1 peak in x-ray diffraction profile was correlated with the contribution of grain boundary scattering in heavily doped GZO films.

  13. Review of Magnetron Developments

    NASA Astrophysics Data System (ADS)

    Vyas, Sandeep Kumar; Verma, Rajendra Kumar; Maurya, Shivendra; Singh, V. V. P.

    2016-09-01

    Magnetrons have been the most efficient high power microwave sources for decades. In the twenty-first century, many of the development works are headed towards the performance improvement of CW industrial magnetrons. In this review article, the development works and techniques, used on different types of magnetrons, for the performance enhancement in the past two decades have been discussed. The article focuses on the state of the art of CW magnetron and the direction it will take in foreseeable future. In addition it also glimpses some of the major variants of magnetron which have further opened up scope in mm-THz spectrum of electromagnetism.

  14. Effect of radio frequency magnetron sputtering power on structural and optical properties of Ti6Al4A thin films

    NASA Astrophysics Data System (ADS)

    Khalaf, Mohammed K.; Al-Taay, H. F.; Ali, Dawood S.

    2017-03-01

    In this research, the effects of target sputtering power on the structure and optical properties of radio frequency (RF) sputtered Ti6Al4V films were investigated. Different sputtering RF powers were used to produce different thicknesses of Ti6Al4V thin films. From the X-ray diffraction, it was found that the Ti6A14V films had polycrystalline cubic and hexagonal structures and increased films crystallinity and crystalline size with increasing the sputtering power. Atomic forces microscopy (AFM) gave us a nanometric film character, films homogeneity, and surfaces roughness. A higher degree of roughness and average grain size with increasing RF power was exhibited. Band gap and refractive index of Ti6Al4V thin films varied with sputtering RF powers.

  15. Microstructure evolution of Al-doped zinc oxide and Sn-doped indium oxide deposited by radio-frequency magnetron sputtering: A comparison

    SciTech Connect

    Nie, Man; Bikowski, Andre; Ellmer, Klaus

    2015-04-21

    The microstructure and morphology evolution of Al-doped zinc oxide (AZO) and Sn-doped indium oxide (ITO) thin films on borosilicate glass substrates deposited by radio-frequency magnetron sputtering at room temperature (RT) and 300 °C were investigated by X-ray diffraction and atomic force microscopy (AFM). One-dimensional power spectral density (1DPSD) functions derived from the AFM profiles, which can be used to distinguish different growth mechanisms, were used to compare the microstructure scaling behavior of the thin films. The rms roughness R{sub q} evolves with film thickness as a power law, R{sub q} ∼ d{sub f}{sup β}, and different growth exponents β were found for AZO and ITO films. For AZO films, β of 1.47 and 0.56 are obtained for RT and 300 °C depositions, respectively, which are caused by the high compressive stress in the film at RT and relaxation of the stress at 300 °C. While for ITO films, β{sub 1} = 0.14 and β{sub 2} = 0.64 for RT, and β{sub 1} = 0.89 and β{sub 2} = 0.3 for 300 °C deposition are obtained, respectively, which is related to the strong competition between the surface diffusion and shadowing effect and/or grain growth. Electrical properties of both materials as a function of film thickness were also compared. By the modified Fuchs-Sondheimer model fitting of the electrical transport in both materials, different nucleation states are pointed out for both types of films.

  16. A study of Ta xC 1 -x coatings deposited on biomedical 316L stainless steel by radio-frequency magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Ding, M. H.; Wang, B. L.; Li, L.; Zheng, Y. F.

    2010-11-01

    In this paper, Ta xC 1 -x coatings were deposited on 316L stainless steel (316L SS) by radio-frequency (RF) magnetron sputtering at various substrate temperatures ( Ts) in order to improve its corrosion resistance and hemocompatibility. XRD results indicated that Ts could significantly change the microstructure of Ta xC 1 -x coatings. When Ts was <150 °C, the Ta xC 1 -x coatings were in amorphous condition, whereas when Ts was ≥150 °C, TaC phase was formed, exhibiting in the form of particulates with the crystallite sizes of about 15-25 nm ( Ts = 300 °C). Atomic force microscope (AFM) results showed that with the increase of Ts, the root-mean-square (RMS) values of the Ta xC 1 -x coatings decreased. The nano-indentation experiments indicated that the Ta xC 1 -x coating deposited at 300 °C had a higher hardness and modulus. The scratch test results demonstrated that Ta xC 1 -x coatings deposited above 150 °C exhibited good adhesion performance. Tribology tests results demonstrated that Ta xC 1 -x coatings exhibited excellent wear resistance. The results of potentiodynamic polarization showed that the corrosion resistance of the 316L SS was improved significantly because of the deposited Ta xC 1 -x coatings. The platelet adhesion test results indicated that the Ta xC 1 -x coatings deposited at Ts of 150 °C and 300 °C possessed better hemocompatibility than the coating deposited at Ts of 25 °C. Additionally, the hemocompatibility of the Ta xC 1 -x coating on the 316L SS was found to be influenced by its surface roughness, hydrophilicity and the surface energy.

  17. An investigation on the effect of high partial pressure of hydrogen on the nanocrystalline structure of silicon carbide thin films prepared by radio-frequency magnetron sputtering.

    PubMed

    Daouahi, Mohsen; Omri, Mourad; Kerm, Abdul Ghani Yousseph; Al-Agel, Faisal Abdulaziz; Rekik, Najeh

    2015-02-05

    The aim of the study reported in this paper is to investigate the role of the high partial pressure of hydrogen introduced during the growth of nanocrystalline silicon carbide thin films (nc-SiC:H). For this purpose, we report the preparation as well as spectroscopic studies of four series of nc-SiC:H obtained by radio-frequency magnetron sputtering at high partial pressure of hydrogen by varying the percentage of H2 in the gas mixture from 70% to 100% at common substrate temperature (TS=500°C). The effects of the dilution on the structural changes and the chemical bonding of the different series have been studied using Fourier transform infrared and Raman spectroscopy. For this range of hydrogen dilution, two groups of films were obtained. The first group is characterized by the dominance of the crystalline phase and the second by a dominance of the amorphous phase. This result confirms the multiphase structure of the grown nc-SiC:H thin films by the coexistence of the SiC network, carbon-like and silicon-like clusters. Furthermore, infrared results show that the SiC bond is the dominant absorption peak and the carbon atom is preferentially bonded to silicon. The maximum value obtained of the crystalline fraction is about 77%, which is relatively important compared to other results obtained by other techniques. In addition, the concentration of CHn bonds was found to be lower than that of SiHn for all series. Raman measurements revealed that the crystallization occurs in all series even at 100% H2 dilution suggesting that high partial pressure of hydrogen favors the formation of silicon nanocrystallites (nc-Si). The absence of both the longitudinal acoustic band and the transverse optical band indicate that the crystalline phase is dominant.

  18. Structural, chemical and nanomechanical investigations of SiC/polymeric a-C:H films deposited by reactive RF unbalanced magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Tomastik, C.; Lackner, J. M.; Pauschitz, A.; Roy, M.

    2016-03-01

    Amorphous carbon (or diamond-like carbon, DLC) films have shown a number of important properties usable for a wide range of applications for very thin coatings with low friction and good wear resistance. DLC films alloyed with (semi-)metals show some improved properties and can be deposited by various methods. Among those, the widely used magnetron sputtering of carbon targets is known to increase the number of defects in the films. Therefore, in this paper an alternative approach of depositing silicon-carbide-containing polymeric hydrogenated DLC films using unbalanced magnetron sputtering was investigated. The influence of the C2H2 precursor concentration in the deposition chamber on the chemical and structural properties of the deposited films was investigated by Raman spectroscopy, X-ray photoelectron spectroscopy and elastic recoil detection analysis. Roughness, mechanical properties and scratch response of the films were evaluated with the help of atomic force microscopy and nanoindentation. The Raman spectra revealed a strong correlation of the film structure with the C2H2 concentration during deposition. A higher C2H2 flow rate results in an increase in SiC content and decrease in hydrogen content in the film. This in turn increases hardness and elastic modulus and decreases the ratio H/E and H3/E2. The highest scratch resistance is exhibited by the film with the highest hardness, and the film having the highest overall sp3 bond content shows the highest elastic recovery during scratching.

  19. Time and frequency dependent rheology of reactive silica gels.

    PubMed

    Wang, Miao; Winter, H Henning; Auernhammer, Günter K

    2014-01-01

    In a mixture of sodium silicate and low concentrated sulfuric acid, nano-sized silica particles grow and may aggregate to a system spanning gel network. We studied the influence of the finite solubility of silica at high pH on the mechanical properties of the gel with classical and piezo-rheometers. Direct preparation of the gel sample in the rheometer cell avoided any pre-shear of the gel structure during the filling of the rheometer. The storage modulus of the gel grew logarithmically with time with two distinct growth laws. The system passes the gel point very quickly but still shows relaxation at low frequency, typically below 6 rad/s. We attribute this as a sign of structural rearrangements due to the finite solubility of silica at high pH. The reaction equilibrium between bond formation and dissolution maintains a relatively large bond dissolution rate, which leads to a finite life time of the bonds and behavior similar to physical gels. This interpretation is also compatible with the logarithmic time dependence of the storage modulus. The frequency dependence was more pronounced for lower water concentrations, higher temperatures and shorter reaction times. With two relaxation models (the modified Cole-Cole model and the empirical Baumgaertel-Schausberger-Winter model) we deduced characteristic times from the experimental data. Both models approximately described the data and resulted in similar relaxation times.

  20. Electrochromic properties and performance of NiOx films and their corresponding all-thin-film flexible devices preparedby reactive DC magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Dong, Dongmei; Wang, Wenwen; Dong, Guobo; Zhang, Fan; He, Yingchun; Yu, Hang; Liu, Famin; Wang, Mei; Diao, Xungang

    2016-10-01

    Nickel oxide (NiOx) thin films were deposited by direct current magnetron sputtering technique onto flexible substrates with various oxygen (O2) partial pressures. The influence of O2 contents during deposition process on film structure, morphology, composition, optical and electrochromic (EC) characteristics of the films were investigated. The EC response for nonstoichiometric NiOx films shows a strong dependence on grain size variations and surface morphology. Finally, the multiple-layer stacks ITO/NiOx/Ta2O5:H/WO3/ITO were sequentially vacuum deposited over flexible polyethylene terephthalate plates based on the optimization of NiOx single layers. A large optical contrast up to 60% and a good durability are obtained for full device. To perform preliminary research on the mechanical properties within flexible devices, we introduced nontrivial changes to the interfacial properties by replacing the glass with flexible polymers. The effects were studied through static bending and the nano-scratch test.

  1. Magnetron sputtering source

    DOEpatents

    Makowiecki, D.M.; McKernan, M.A.; Grabner, R.F.; Ramsey, P.B.

    1994-08-02

    A magnetron sputtering source for sputtering coating substrates includes a high thermal conductivity electrically insulating ceramic and magnetically attached sputter target which can eliminate vacuum sealing and direct fluid cooling of the cathode assembly. The magnetron sputtering source design results in greater compactness, improved operating characteristics, greater versatility, and low fabrication cost. The design easily retrofits most sputtering apparatuses and provides for safe, easy, and cost effective target replacement, installation, and removal. 12 figs.

  2. Magnetron sputtering source

    DOEpatents

    Makowiecki, Daniel M.; McKernan, Mark A.; Grabner, R. Fred; Ramsey, Philip B.

    1994-01-01

    A magnetron sputtering source for sputtering coating substrates includes a high thermal conductivity electrically insulating ceramic and magnetically attached sputter target which can eliminate vacuum sealing and direct fluid cooling of the cathode assembly. The magnetron sputtering source design results in greater compactness, improved operating characteristics, greater versatility, and low fabrication cost. The design easily retrofits most sputtering apparatuses and provides for safe, easy, and cost effective target replacement, installation, and removal.

  3. Effect of Al content, substrate temperature and nitrogen flow on the reactive magnetron co-sputtered nanostructure in TiAlN thin films intended for use as barrier material in DRAMs

    NASA Astrophysics Data System (ADS)

    Jalali, Reza; Parhizkar, Mojtaba; Bidadi, Hasan; Naghshara, Hamid; Hosseini, Seyd Reza; Jafari, Majid

    2015-03-01

    TiAlN thin films were deposited by using the reactive magnetron co-sputtering method whit individual Ti and Al targets, where the Ti and the Al targets were simultaneously powered by using DC and RF sources, respectively. the electrical resistivity and the structural and microstructural properties of the deposited TiAlN thin films and the effects of Al content, substrate temperature and nitrogen gas flow rate on those properties were investigated. At a low flow rate of nitrogen gas (0.51 sccm), the electrical resistivity of the films was found to increase with increasing AC power, but at a high flow rate of nitrogen gas, it was found to decrease. The structural and microstructural analyses performed by using X-ray diffraction and scanning electron microscopy (SEM) showed that with increasing substrate temperature from room temperature to 400 ℃, the films prepared at 400 ℃ have a crystalline structure while those prepared at room temperature had an amorphous nature. Also, the SEM analysis revealed that with decreasing AC power and increasing nitrogen flow rate, the size of the grains in the prepared films become larger.

  4. The effect of Al content, substrate temperature and nitrogen flow rate on optical band gap and optical features of nanostructured TiAlN thin films prepared by reactive magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Jalali, Reza; Parhizkar, Mojtaba; Bidadi, Hassan; Naghshara, Hamid; Hosseini, Seyd Reza; Jafari, Majid

    2016-11-01

    In the present work, TiAlN thin films were prepared by using a dual reactive magnetron sputtering system on fused quartz substrates kept at room temperature and 400 °C; keeping nitrogen flow at 0.51 and 2.78 sccm, various DC and RF powers and the effect of these factors have been studied on the optical properties of the layers. The optical properties including absorption and transmission were studied by a UV-Visible spectrophotometer in the wavelength region (200-1100) nm. By plotting ( αhν)2 and ( αhν)1/2 versus the photon energy hυ, the optical band gap was evaluated. Experimental results show that layers with high percentage of aluminum and nitrogen have higher gap with respect to layers having high titanium percentage. TiAlN thin films deposited with 2.78 sccm nitrogen flow rate possess optical direct band gap in the range of 3.8-5.1 eV and optical indirect band gap in the range of 1.1-3.4 eV. The variation of optical band gap of the films that deposited on the substrate with 400 °C and nitrogen flow rate of 2.78 sccm was different from other layers.

  5. A flexible active and reactive power control strategy for a variable speed constant frequency generating system

    SciTech Connect

    Tang, Y.; Xu, L.

    1995-07-01

    Variable-speed constant-frequency generating systems are used in wind power, hydro power, aerospace, and naval power generations to enhance efficiency and reduce friction. In these applications, an attractive candidate is the slip power recovery system comprising of doubly excited induction machine or doubly excited brushless reluctance machine and PWM converters with a dc link. In this paper, a flexible active and reactive power control strategy is developed, such that the optimal torque-speed profile of the turbine can be followed and overall reactive power can be controlled, while the machine copper losses have been minimized. At the same time, harmonics injected into the power network has also been minimized. In this manner, the system can function as both a high-efficient power generator and a flexible reactive power compensator.

  6. Effects of different frequencies of transcutaneous electrical nerve stimulation on venous vascular reactivity

    PubMed Central

    Franco, O.S.; Paulitsch, F.S.; Pereira, A.P.C.; Teixeira, A.O.; Martins, C.N.; Silva, A.M.V.; Plentz, R.D.M.; Irigoyen, M.C.; Signori, L.U.

    2014-01-01

    Transcutaneous electrical nerve stimulation (TENS) is a type of therapy used primarily for analgesia, but also presents changes in the cardiovascular system responses; its effects are dependent upon application parameters. Alterations to the cardiovascular system suggest that TENS may modify venous vascular response. The objective of this study was to evaluate the effects of TENS at different frequencies (10 and 100 Hz) on venous vascular reactivity in healthy subjects. Twenty-nine healthy male volunteers were randomized into three groups: placebo (n=10), low-frequency TENS (10 Hz, n=9) and high-frequency TENS (100 Hz, n=10). TENS was applied for 30 min in the nervous plexus trajectory from the superior member (from cervical to dorsal region of the fist) at low (10 Hz/200 μs) and high frequency (100 Hz/200 μs) with its intensity adjusted below the motor threshold and intensified every 5 min, intending to avoid accommodation. Venous vascular reactivity in response to phenylephrine, acetylcholine (endothelium-dependent) and sodium nitroprusside (endothelium-independent) was assessed by the dorsal hand vein technique. The phenylephrine effective dose to achieve 70% vasoconstriction was reduced 53% (P<0.01) using low-frequency TENS (10 Hz), while in high-frequency stimulation (100 Hz), a 47% increased dose was needed (P<0.01). The endothelium-dependent (acetylcholine) and independent (sodium nitroprusside) responses were not modified by TENS, which modifies venous responsiveness, and increases the low-frequency sensitivity of α1-adrenergic receptors and shows high-frequency opposite effects. These changes represent an important vascular effect caused by TENS with implications for hemodynamics, inflammation and analgesia. PMID:24820225

  7. Study on mixed vanadium oxide thin film deposited by RF magnetron sputtering and its application

    NASA Astrophysics Data System (ADS)

    Ling, Zhang; Jianhui, Tu; Hao, Feng; Jingzhong, Cui

    Vanadium oxide (VOx) thin films were deposited on fused quartz using a pure metal vanadium target by RF reactive magnetron sputtering technique. Film microstructure, valence state, optical transmittance properties were studied. The mixed valence VOx thin films deposited with different thickness were found to be amorphous. And the optical transmittance curves are flatness in certain wavelength region. These films can be used to control the relative light intensity of the rubidium light beam between the rubidium lamp and the vapor cell, in order to optimize the working parameters of the rubidium frequency standard (RAFS).

  8. Optical properties of SrTiO3 thin films deposited by radio-frequency magnetron sputtering at various substrate temperatures

    NASA Astrophysics Data System (ADS)

    Ma, J. H.; Huang, Z. M.; Meng, X. J.; Liu, S. J.; Zhang, X. D.; Sun, J. L.; Xue, J. Q.; Chu, J. H.; Li, J.

    2006-02-01

    SrTiO3 thin films were deposited on vitreous silica substrates at various substrate temperatures (300-700 °C) by rf magnetron sputtering technique. The transition from amorphous phase to polycrystalline phase for the films occurred at the substrate temperatures of 300-400 °C. Their optical properties were investigated by transmittance measurements. The fitting method was used to calculate the refractive index and the film thickness from the transparent region of the transmittance spectra. The refractive index increased and the film thickness decreased with the substrate temperatures increasing. The dispersion of the refractive index was studied by considering a single electronic oscillator model. The band gaps of the films were estimated from Tauc's law and showed a decreasing tendency to that of the bulk SrTiO3 with the substrate temperatures increasing. These results provide some useful references for the potential application of SrTiO3 films in integrated optics devices.

  9. Characteristics and Time-Dependent Instability of Ga-Doped ZnO Thin Film Transistor Fabricated by Radio Frequency Magnetron Sputtering

    NASA Astrophysics Data System (ADS)

    Huang, Hai-Qin; Sun, Jian; Liu, Feng-Juan; Zhao, Jian-Wei; Hu, Zuo-Fu; Li, Zhen-Jun; Zhang, Xi-Qing; Wang, Yong-Sheng

    2011-12-01

    We report on the fabrication and electrical characteristics of Ga-doped ZnO thin film transistors (TFTs). Low Ga-doped (0.7wt%) ZnO thin films were deposited on SiO2/p-Si substrates by rf magnetron sputtering. The GZO TFTs show a mobility of 1.76 cm2/V·s, an on/off ratio of 1.0 × 106, and a threshold voltage of 35 V. The time-dependent instability of the TFT is studied. The VTH shifts negatively. In addition, the device shows a decrease of the on/off ratio, mainly due to the increase of the off-current. The mechanisms of instability are discussed.

  10. Fabrication of P-Type ZnO:N Film by Radio-Frequency Magnetron Sputtering for Extremely Thin Absorber Solar Cell Applications

    NASA Astrophysics Data System (ADS)

    Wang, Xiang-Hu; Li, Rong-Bin; Fan, Dong-Hua

    2013-03-01

    We successfully fabricate p-type ZnO:N films by using rf magnetron sputtering and in situ annealing in O2 atmosphere. These p-type ZnO:N films can be used as p-type window materials for extremely thin absorber (ETA) solar cells composed of quartz glass/p-ZnO:N/i-ZnO/CdSe/i-ZnO/n-ZnO:Al. The short-circuit photocurrent density, open circuit voltage, fill factor and conversion efficiency of the ETA solar cells can be determined to be 8.549 mA/cm2, 0.702V, 0.437 and 2.623%, respectively, through measurements of photovoltaic properties under illumination with a 100mW/cm2 at air-mass (AM) 1.5.

  11. Compact Relativistic Magnetron with Output Mode Converter

    NASA Astrophysics Data System (ADS)

    Andreev, Andrey; Fuks, Mikhail; Schamiloglu, Edl

    2003-10-01

    We consider a relativistic magnetron in which all of the resonators of the anode block are smoothly continued onto a conical antenna up to the radius corresponding to the cutoff frequency of the radiated wave in a cylindrical waveguide. Such a magnetron is capable of high output power, is compact, has a high resistance to microwave breakdown, is able to work with extremely high currents, and has the possibility of forming desirable output radiation patterns. The magnetic field can be provided by a small solenoid over the resonant system, which is a much smaller volume than is required for the Helmholtz coils used in traditional relativistic magnetrons. The maximum size of this magnetron is the aperture of the horn antenna. The unique aspect of such a design is the possibility of using the horn antenna for conversion of the operating mode to lower order modes, including the TE_11 mode, which is radiated as a narrow wave beam. For a magnetron operating in π-mode, the mode converter comprises a continuation of the resonantor blocks onto the horn for those resonators that correspond to the symmetry of the output mode. For example, in order to provide Gaussian mode output only two diametrically opposite resonators of even-numbered resonators must be continued onto the horn. In this case the aperture of the horn antenna can be close to the cut-off diameter for the TE_11 mode, and the output power is limited only by breakdown of the output window. In this presentation results of preliminary calculations of the magnetron with output mode converters are presented.

  12. Modeling and experimental studies of a side band power re-injection locked magnetron

    NASA Astrophysics Data System (ADS)

    Ye, Wen-Jun; Zhang, Yi; Yuan, Ping; Zhu, Hua-Cheng; Huang, Ka-Ma; Yang, Yang

    2016-12-01

    A side band power re-injection locked (SBPRIL) magnetron is presented in this paper. A tuning stub is placed between the external injection locked (EIL) magnetron and the circulator. Side band power of the EIL magnetron is reflected back to the magnetron. The reflected side band power is reused and pulled back to the central frequency. A phase-locking model is developed from circuit theory to explain the process of reuse of side band power in SBPRIL magnetron. Theoretical analysis proves that the side band power is pulled back to the central frequency of the SBPRIL magnetron, then the amplitude of the RF voltage increases and the phase noise performance is improved. Particle-in-cell (PIC) simulation of a 10-vane continuous wave (CW) magnetron model is presented. Computer simulation predicts that the frequency spectrum’s peak of the SBPRIL magnetron has an increase of 3.25 dB compared with the free running magnetron. The phase noise performance at the side band offset reduces 12.05 dB for the SBPRIL magnetron. Besides, the SBPRIL magnetron experiment is presented. Experimental results show that the spectrum peak rises by 14.29% for SBPRIL magnetron compared with the free running magnetron. The phase noise reduces more than 25 dB at 45-kHz offset compared with the free running magnetron. Project supported by the National Basic Research Program of China (Grant No. 2013CB328902) and the National Natural Science Foundation of China (Grant No. 61501311).

  13. Solid oxide fuel cells with (La,Sr)(Ga,Mg)O3-δ electrolyte film deposited by radio-frequency magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Wang, Sea-Fue; Lu, His-Chuan; Hsu, Yung-Fu; Hu, Yi-Xuan

    2015-05-01

    In this study, solid oxide fuel cells (SOFCs) containing a high quality La0.9Sr0.1Ga0.8Mg0.2O3-δ (LSGM) film deposited on anode supported substrate using RF magnetron sputtering are successfully prepared. The anode substrate is composed of two functional NiO/Sm0.2Ce0.8O2-δ (SDC) composite layers with ratios of 60/40 wt% and 50/50 wt% and a current collector layer of pure NiO. The as-deposited LSGM film appears to be amorphous in nature. After post-annealing at 1000 °C, a uniform and dense polycrystalline film with a composition of La0.87Sr0.13Ga0.85Mg0.15O3-δ and a thickness of 3.8 μm is obtained, which was well adhered to the anode substrate. A composite LSGM/La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF) layer, with a ratio of 30/70 wt%, is used as the cathode. The SOFC prepared reveals a good mechanical integrity with no sign of cracking, delamination, or discontinuity among the interfaces. The total cell resistance of a single cell with LSGM electrolyte film declines from 0.60 to 0.10 Ω cm2 as the temperature escalates from 600 to 800 °C and the open circuit voltage (OCV) ranges from 0.85 to 0.95 V. The maximum power density (MPD) of the single cell is reported as 0.65, 1.02, 1.30, 1.42, and 1.38 W cm-2 at 600, 650, 700, 750, and 800 °C, respectively. The good cell performance leads to the conclusion that RF magnetron sputtering is a feasible deposition method for preparing good quality LSGM films in SOFCs.

  14. Electrochemical properties of Sn-substituted LiMn2O4 thin films prepared by radio-frequency magnetron sputtering.

    PubMed

    Kong, Woo Yeon; Yim, Haena; Yoon, Seok-Jin; Nahm, Sahn; Choi, Ji-Won

    2013-05-01

    The LiMn2O4 and LiSn0.0125Mn1975O4 thin films were grown on Pt/Ti/SiO2/Si (100) substrate by RF magnetron sputtering. To obtain the structural stability and good cycle performance, deposition parameters, namely working pressure, sputtering gas ratio of Ar and O2, post-annealing temperature were established. The structure and surface morphology of thin films were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. The electrochemical properties were estimated by two electrode half-cell test with WBCS 3000 (Wonatech, Korea) at constant current rate of 1 C-rate. The Sn substituted LiMn2O4 thin film deposited at 10 mtorr with mixture of argon and oxygen (Ar/O2 = 3/1) and then annealed at 500 degrees C in O2 atmosphere showed good cycle performance. The Sn substituted LiMn2O4 thin films showed larger capacity of -30 microAh/microm-cm2 and higher cyclability than LiMn2O4 thin films.

  15. Single frequency sound propagation in flat waveguides with locally reactive impedance boundaries.

    PubMed

    Min, Hequn; Chen, Weisong; Qiu, Xiaojun

    2011-08-01

    A coherent image source method is presented for evaluating single frequency sound propagation from a point source in a flat waveguide with two infinite and parallel locally reactive boundaries. The method starts from formulating reflections of the spherical sound radiation into integrals of plane wave expansion, and the analytical evaluation of the integrals is simplified by introducing a physically plausible assumption that wave front shapes remain the same before and after each reflection on a reflective boundary. The proposed model can determine coherently the sound fields at arbitrary receiver locations in a flat waveguide, even when one boundary is highly sound absorptive. Being compared with the classical wave theory and the existing coherent ray-based methods, it is shown that the proposed method provides considerable accuracy and advantages to predict sound propagation in flat waveguides with a sound absorptive ceiling and a reflective floor over a broad frequency range, particularly at large distances from the source where the existing methods are problematic.

  16. High power impulse magnetron sputtering discharge

    SciTech Connect

    Gudmundsson, J. T.; Brenning, N.; Lundin, D.; Helmersson, U.

    2012-05-15

    The high power impulse magnetron sputtering (HiPIMS) discharge is a recent addition to plasma based sputtering technology. In HiPIMS, high power is applied to the magnetron target in unipolar pulses at low duty cycle and low repetition frequency while keeping the average power about 2 orders of magnitude lower than the peak power. This results in a high plasma density, and high ionization fraction of the sputtered vapor, which allows better control of the film growth by controlling the energy and direction of the deposition species. This is a significant advantage over conventional dc magnetron sputtering where the sputtered vapor consists mainly of neutral species. The HiPIMS discharge is now an established ionized physical vapor deposition technique, which is easily scalable and has been successfully introduced into various industrial applications. The authors give an overview of the development of the HiPIMS discharge, and the underlying mechanisms that dictate the discharge properties. First, an introduction to the magnetron sputtering discharge and its various configurations and modifications is given. Then the development and properties of the high power pulsed power supply are discussed, followed by an overview of the measured plasma parameters in the HiPIMS discharge, the electron energy and density, the ion energy, ion flux and plasma composition, and a discussion on the deposition rate. Finally, some of the models that have been developed to gain understanding of the discharge processes are reviewed, including the phenomenological material pathway model, and the ionization region model.

  17. The effects of vibration on explosive and reactive strength when applying individualized vibration frequencies.

    PubMed

    Di Giminiani, Riccardo; Tihanyi, Jozsef; Safar, Sandor; Scrimaglio, Renato

    2009-01-15

    The aim of this study was to assess the effects of 8 weeks of whole-body vibrations on explosive and reactive leg strength. Thirty-three physically active students took part in the study and were randomly assigned to an individualized-vibration group, a fixed-vibration group or a control group. The frequency of vibration was set to 30 Hz for the fixed-vibration group, whereas the frequency for the individualized-vibration group was determined by monitoring the participants' EMGrms activity. The participants in the two vibration groups were exposed three times a week for 8 weeks to a series of 10 x 1-min whole-body vibrations with a 1-min pause between series of vibrations and a 4-min pause after the first five series of vibrations. Jump height in the squat jump increased significantly in all three groups (by 11% for the individualized-vibration group, p=0.001; by 3% for the fixed-vibration group, p=0.011; and by 2% for the control group, p=0.006), but countermovement jump height was not affected. In continuous rebound jumps by the individualized-vibration group, jumping height increased by 22% (p=0.006) and power increased by 18% (p=0.002). The results of this study suggest that the use of an individualized vibration frequency produces a greater response from the neuromuscular system and is more beneficial than vibrations at a fixed pre-selected frequency.

  18. Derivation and generalization of the dispersion relation of rising-sun magnetron with sectorial and rectangular cavities

    SciTech Connect

    Shi, Di-Fu; Qian, Bao-Liang; Wang, Hong-Gang; Li, Wei

    2013-12-15

    Field analysis method is used to derive the dispersion relation of rising-sun magnetron with sectorial and rectangular cavities. This dispersion relation is then extended to the general case in which the rising-sun magnetron can be with multi-group cavities of different shapes and sizes, and from which the dispersion relations of conventional magnetron, rising-sun magnetron, and magnetron-like device can be obtained directly. The results show that the relative errors between the theoretical and simulation values of the dispersion relation are less than 3%, the relative errors between the theoretical and simulation values of the cutoff frequencies of π mode are less than 2%. In addition, the influences of each structure parameter of the magnetron on the cutoff frequency of π mode and on the mode separation are investigated qualitatively and quantitatively, which may be of great interest to designing a frequency tuning magnetron.

  19. Magnetron sputtered boron films

    DOEpatents

    Makowiecki, D.M.; Jankowski, A.F.

    1998-06-16

    A method is described for the production of thin boron and titanium/boron films by magnetron sputter deposition. The amorphous boron films contain no morphological growth features, unlike those found when thin films are prepared by various physical vapor deposition processes. Magnetron sputter deposition method requires the use of a high density crystalline boron sputter target which is prepared by hot isostatic pressing. Thin boron films prepared by this method are useful for producing hardened surfaces, surfacing machine tools, etc. and for ultra-thin band pass filters as well as the low Z element in low Z/high Z optical components, such as mirrors which enhance reflectivity from grazing to normal incidence. 8 figs.

  20. Magnetron sputtered boron films

    DOEpatents

    Makowiecki, Daniel M.; Jankowski, Alan F.

    1998-01-01

    A method is described for the production of thin boron and titanium/boron films by magnetron sputter deposition. The amorphous boron films contain no morphological growth features, unlike those found when thin films are prepared by various physical vapor deposition processes. Magnetron sputter deposition method requires the use of a high density crystalline boron sputter target which is prepared by hot isostatic pressing. Thin boron films prepared by this method are useful for producing hardened surfaces, surfacing machine tools, etc. and for ultra-thin band pass filters as well as the low Z element in low Z/high Z optical components, such as mirrors which enhance reflectivity from grazing to normal incidence.

  1. A regulated magnetron pulser

    SciTech Connect

    Rose, C.R.

    1997-09-01

    This paper describes and analysis of a 4.5-kV, 500-mA, regulated current pulser used to drive a Hitachi ZM130 magnetron in a particle-accelerator injector. In this application, precise beam from the injector. A high-voltage triode vacuum tube with active feedback is used to control the magnetron current. Current regulation and accuracy is better than 1%. The pulse width may be varied from as little as 5 {mu}m to cw by varying the width of a gate pulse. The current level can be programmed between 10 and 500 mA. Design of the pulser including circuit simulations, power calculations, and high-voltage issues are discussed.

  2. Magnetron injection gun scaling

    NASA Astrophysics Data System (ADS)

    Lawson, W.

    1988-04-01

    A set of tradeoff equations was simplified to obtain scaling laws for magnetron injection guns (MIGs). The constraints are chosen to examine the maximum-peak-power capabilities of MIGs. The scaling laws are compared with exact solutions of the design equations and are supported by MIG simulations in which each MIG is designed to double the beam power of an existing design by adjusting one of the four fundamental parameters.

  3. A reactive magnetron sputtering route for attaining a controlled core-rim phase partitioning in Cu{sub 2}O/CuO thin films with resistive switching potential

    SciTech Connect

    Ogwu, A. A.; Darma, T. H.

    2013-05-14

    The achievement of a reproducible and controlled deposition of partitioned Cu{sub 2}O/CuO thin films by techniques compatible with ULSI processing like reactive magnetron sputtering has been reported as an outstanding challenge in the literature. This phase partitioning underlies their performance as reversible resistive memory switching devices in advanced microelectronic applications of the future. They are currently fabricated by thermal oxidation and chemical methods. We have used a combination of an understanding from plasma chemistry, thermo-kinetics of ions, and rf power variation during deposition to successfully identify a processing window for preparing partitioned Cu{sub 2}O/CuO films. The production of a core rich Cu{sub 2}O and surface rich Cu{sub 2}O/CuO mixture necessary for oxygen migration during resistive switching is confirmed by XRD peaks, Fourier transform infra red Cu (I)-O vibrational modes, XPS Cu 2P{sub 3/2} and O 1S peak fitting, and a comparison of satellite peak ratio's in Cu 2P{sub 3/2} fitted peaks. We are proposing based on the findings reported in this paper that an XPS satellite peak intensity(I{sub s}) to main peak intensity ratio (I{sub m}) {<=} 0.45 as an indicator of a core rich Cu{sub 2}O and surface rich Cu{sub 2}O/CuO formation in our prepared films. CuO is solely responsible for the satellite peaks. This is explained on the basis that plasma dissociation of oxygen will be limited to the predominant formation of Cu{sub 2}O under certain plasma deposition conditions we have identified in this paper, which also results in a core-rim phase partitioning. The deposited films also followed a Volmer-Weber columnar growth mode, which could facilitate oxygen vacancy migration and conductive filaments at the columnar interfaces. This is further confirmed by optical transmittance and band-gap measurements using spectrophotometry. This development is expected to impact on the early adoption of copper oxide based resistive memory

  4. Second order elasticity at hypersonic frequencies of reactive polyurethanes as seen by generalized Cauchy relations.

    PubMed

    Philipp, M; Vergnat, C; Müller, U; Sanctuary, R; Baller, J; Possart, W; Alnot, P; Krüger, J K

    2009-01-21

    The non-equilibrium process of polymerization of reactive polymers can be accompanied by transition phenomena like gelation or the chemical glass transition. The sensitivity of the mechanical properties at hypersonic frequencies-including the generalized Cauchy relation-to these transition phenomena is studied for three different polyurethanes using Brillouin spectroscopy. As for epoxies, the generalized Cauchy relation surprisingly holds true for the non-equilibrium polymerization process and for the temperature dependence of polyurethanes. Neither the sol-gel transition nor the chemical and thermal glass transitions are visible in the representation of the generalized Cauchy relation. Taking into account the new results and combining them with general considerations about the elastic properties of the isotropic state, an improved physical foundation of the generalized Cauchy relation is proposed.

  5. Brain reactivity differentiates subjects with high and low dream recall frequencies during both sleep and wakefulness.

    PubMed

    Eichenlaub, Jean-Baptiste; Bertrand, Olivier; Morlet, Dominique; Ruby, Perrine

    2014-05-01

    The neurophysiological correlates of dreaming remain unclear. According to the "arousal-retrieval" model, dream encoding depends on intrasleep wakefulness. Consistent with this model, subjects with high and low dream recall frequency (DRF) report differences in intrasleep awakenings. This suggests a possible neurophysiological trait difference between the 2 groups. To test this hypothesis, we compared the brain reactivity (evoked potentials) of subjects with high (HR, N = 18) and low (LR, N = 18) DRF during wakefulness and sleep. During data acquisition, the subjects were presented with sounds to be ignored (first names randomly presented among pure tones) while they were watching a silent movie or sleeping. Brain responses to first names dramatically differed between the 2 groups during both sleep and wakefulness. During wakefulness, the attention-orienting brain response (P3a) and a late parietal response were larger in HR than in LR. During sleep, we also observed between-group differences at the latency of the P3a during N2 and at later latencies during all sleep stages. Our results demonstrate differences in the brain reactivity of HR and LR during both sleep and wakefulness. These results suggest that the ability to recall dreaming is associated with a particular cerebral functional organization, regardless of the state of vigilance.

  6. Oleophobic optical coating deposited by magnetron PVD

    NASA Astrophysics Data System (ADS)

    Bernt, D.; Ponomarenko, V.; Pisarev, A.

    2016-09-01

    Thin oxinitride films of Zn-Sn-O-N and Si-Al-O-N were deposited on glass by reactive magnetron sputtering at various nitrogen-to-oxygen ratios. Nitrogen added to oxygen led to decrease of the surface roughness and increase of oleophobic properties studied by the oil-drop test. The best oleophobity was obtained for Zn-Sn-O-N oxinitride at Zn:Sn=1:1 and N:O=1:2. Improved oleophobic properties were also demonstrated if the oxinitride film was deposited on top of the multilayer coating as the final step in the industrial cycle of production of energy efficient glass.

  7. Extending the photoresponse of TiO2 to the visible light region: photoelectrochemical behavior of TiO2 thin films prepared by the radio frequency magnetron sputtering deposition method.

    PubMed

    Kikuchi, Hisashi; Kitano, Masaaki; Takeuchi, Masato; Matsuoka, Masaya; Anpo, Masakazu; Kamat, Prashant V

    2006-03-23

    TiO(2) thin films prepared by a radio frequency magnetron sputtering (RF-MS) deposition method were found to show an enhanced photoelectrochemical response in the visible light region. By controlling the temperature and the gaseous medium during the deposition step, it was possible to control the properties of these films. The photoelectrochemical behavior of the sputtered TiO(2) thin films was compared with that of a commercial TiO(2) sample, and the sputtered films showed higher incident photon to the charge carrier generation efficiency (IPCE of 12.6% at 350 nm) as well as power conversion efficiency (0.33% at 1.84 mW/cm(2)) than the commercial TiO(2) sample. Femtosecond transient absorption spectroscopy experiments have revealed that a major fraction of photogenerated electrons and holes recombine within a few picoseconds, thus limiting photocurrent generation efficiency. The mechanistic insights obtained in the present study should aid in designing semiconductor nanostructures that will maximize the charge separation efficiency and extend the response of the large band gap semiconductor TiO(2) into visible light regions.

  8. The evaluation of increase in hemodialysis frequency on C-reactive protein levels and nutritional status.

    PubMed

    Rashidi, Ali Akbar; Soleimani, Ali Reza; Nikoueinejad, Hassan; Sarbolouki, Shokooh

    2013-03-16

    Malnutrition and inflammation are the most important causes of cardiovascular disease in hemodialysis patients. This study was conducted to evaluate the effect of increase in hemodialysis frequency on C-reactive protein (CRP) level and nutritional markers in contrast to previous routine method. 18 hemodialysis patients with a mean age of 53±16 years were randomly selected in this before-and-after clinical trial. The patients under a standard hemodialysis of 3 times/4 h per week were converted to 4 times/4 h for a period of 6 weeks. The CRP, albumin, triglyceride, total cholesterol, LDL, HDL serum levels, anthropometric indices and 24-h diet recall intake was assessed before and after of the period. The data were analyzed using paired t-test, and P-value less than 0.05 was considered significant. All patients completed the study. Mean weight, body mass index and serum albumin increased while serum CRP level decreased significantly after the intervention (P<0.03). Triglyceride, total cholesterol, LDL, HDL, as well as energy, protein and fat intake had no significant change before and after the study. Increase in dialysis frequency decreased systemic inflammation and improved the nutritional state of hemodialysis patients. Therefore, it may decrease the risk of cardiovascular events in these patients.

  9. Magic-T-Coupled Magnetrons

    NASA Technical Reports Server (NTRS)

    Dickinson, R. M.

    1985-01-01

    Outputs of two magnetrons added coherently in scheme based on resonant waveguide coupling and injection phase locking. In addition, filaments are turned off after starting. Overall effect is relatively-inexpensive, lowpower, noisy magnetrons generate clean carrier signals of higher power that ordinarily require more expensive klystrons.

  10. The dislocation density and twin-boundary frequency determined by X-ray peak profile analysis in cold rolled magnetron-sputter deposited nanotwinned copper

    SciTech Connect

    Csiszar, Gabor; Ungar, Tamas; Balogh, Levente; Misra, Amit; Zhang Xinghang

    2011-08-15

    The dislocation density and the average twin boundary frequency is determined quantitatively in as-deposited and cold-rolled nanotwinned Cu thin films by high-resolution X-ray line profile analysis. After cold-rolling the dislocation density increases considerably, whereas the twin boundary frequency decreases only slightly. The physical parameters of the substructure provided by the quantitative X-ray analysis are in agreement with earlier transmission electron microscopy observations. The flow stress of the as-deposited and the cold-rolled films is directly correlated with the average thickness of twin lamellae and the dislocation density by taking into account the Hall-Petch and Taylor type strengthening mechanisms.

  11. Recirculating planar magnetrons: simulations and experiment

    SciTech Connect

    Franzi, Matthew; Gilgenbach, Ronald; French, David; Lau, Y.Y.; Simon, David; Hoff, Brad; Luginsland, John W.

    2011-07-01

    The Recirculating Planar Magnetron (RPM) is a novel crossed-field device whose geometry is expected to reduce thermal load, enhance current yield as well as ease the geometric limitations in scaling to high RF frequencies as compared to the conventional cylindrical magnetrons. The RPM has two different adaptations: A. Axial B field and radial E field; B. Radial B field and axial E field. The preliminary configuration (A) to be used in experiments at the University of Michigan consists of two parallel planar sections which join on either end by cylindrical regions to form a concentric extruded ellipse. Similar to conventional magnetrons, a voltage across the AK gap in conjunction with an axial magnetic field provides the electrons with an ExB drift. The device is named RPM because the drifting electrons recirculate from one planar region to the other. The drifting electrons interact with the resonantly tuned slow wave structure on the anode causing spoke formation. These electron spokes drive a RF electric field in the cavities from which RF power may be extracted to Waveguides. The RPM may be designed in either a conventional configuration with the anode on the outside, for simplified extraction, or as an inverted magnetron with the anode at the inner conductor, for fast start-up. Currently, experiments at the Pulsed Power and Microwave Laboratory at the University of Michigan are in the setup and design phase. A conventional RPM with planar cavities is to be installed on the Michigan Electron Long Beam Accelerator (MELBA) and is anticipated to operate at -200kV, 0.2T with a beam current of 1-10 kA at 1GHz. The conventional RPM consists of 12 identical planar cavities, 6 on each planar side, with simulated quality factor of 20.

  12. Nonsputtering impulse magnetron discharge

    SciTech Connect

    Khodachenko, G. V.; Mozgrin, D. V.; Fetisov, I. K.; Stepanova, T. V.

    2012-01-15

    Experiments with quasi-steady high-current discharges in crossed E Multiplication-Sign B fields in various gases (Ar, N{sub 2}, H{sub 2}, and SF{sub 6}) and gas mixtures (Ar/SF{sub 6} and Ar/O{sub 2}) at pressures from 10{sup -3} to 5 Torr in discharge systems with different configurations of electric and magnetic fields revealed a specific type of stable low-voltage discharge that does not transform into an arc. This type of discharge came to be known as a high-current diffuse discharge and, later, a nonsputtering impulse magnetron discharge. This paper presents results from experimental studies of the plasma parameters (the electron temperature, the plasma density, and the temperature of ions and atoms of the plasma-forming gas) of a high-current low-pressure diffuse discharge in crossed E Multiplication-Sign B fields.

  13. Control of Reactive Species Generated by Low-frequency Biased Nanosecond Pulse Discharge in Atmospheric Pressure Plasma Effluent

    NASA Astrophysics Data System (ADS)

    Takashima, Keisuke; Kaneko, Toshiro

    2016-09-01

    The control of hydroxyl radical and the other gas phase species generation in the ejected gas through air plasma (air plasma effluent) has been experimentally studied, which is a key to extend the range of plasma treatment. Nanosecond pulse discharge is known to produce high reduced electric field (E/N) discharge that leads to efficient generation of the reactive species than conventional low frequency discharge, while the charge-voltage cycle in the low frequency discharge is known to be well-controlled. In this study, the nanosecond pulse discharge biased with AC low frequency high voltage is used to take advantages of these discharges, which allows us to modulate the reactive species composition in the air plasma effluent. The utilization of the gas-liquid interface and the liquid phase chemical reactions between the modulated long-lived reactive species delivered from the air plasma effluent could realize efficient liquid phase chemical reactions leading to short-lived reactive species production far from the air plasma, which is crucial for some plasma agricultural applications.

  14. Simulation and Experimental Studies of a 2.45GHz Magnetron Source for an SRF Cavity with Field Amplitude and Phase Controls

    SciTech Connect

    Wang, Haipeng; Plawski, Tomasz E.; Rimmer, Robert A.; Dudas, A.; Neubauer, M. L.

    2016-06-01

    Phase lock to an SRF cavity by using injection signal through output waveguide of a magnetron has been demonstrated [1, 3]. Amplitude control using magnetic field trimming and anode voltage modulation has been studied using MATLAB/Simulink simulations [2]. Based on these, we are planning to use an FPGA based digital LLRF system, which allows applying various types of control algorithms in order to achieve the required accelerating field stability. Since the 1497 MHz magnetron is still in the design stage, the proof of principle measurements of a commercial 2450 MHz magnetron are carried out to characterize the anode I-V curve, output power (the tube electronic efficiency), frequency dependence on the anode current (frequency pushing) and the Rieke diagram (frequency pulling by the reactive load). Based on early Simulink simulation, experimental data and extension of the Adler equation governing injection phase stability by Chen’s model, the specification of the new LLRF control chassis for both 2450 and 1497MHz systems are presented in this paper.

  15. Alpha reactivity to first names differs in subjects with high and low dream recall frequency.

    PubMed

    Ruby, Perrine; Blochet, Camille; Eichenlaub, Jean-Baptiste; Bertrand, Olivier; Morlet, Dominique; Bidet-Caulet, Aurélie

    2013-01-01

    Studies in cognitive psychology showed that personality (openness to experience, thin boundaries, absorption), creativity, nocturnal awakenings, and attitude toward dreams are significantly related to dream recall frequency (DRF). These results suggest the possibility of neurophysiological trait differences between subjects with high and low DRF. To test this hypothesis we compared sleep characteristics and alpha reactivity to sounds in subjects with high and low DRF using polysomnographic recordings and electroencephalography (EEG). We acquired EEG from 21 channels in 36 healthy subjects while they were presented with a passive auditory oddball paradigm (frequent standard tones, rare deviant tones and very rare first names) during wakefulness and sleep (intensity, 50 dB above the subject's hearing level). Subjects were selected as High-recallers (HR, DRF = 4.42 ± 0.25 SEM, dream recalls per week) and Low-recallers (LR, DRF = 0.25 ± 0.02) using a questionnaire and an interview on sleep and dream habits. Despite the disturbing setup, the subjects' quality of sleep was generally preserved. First names induced a more sustained decrease in alpha activity in HR than in LR at Pz (1000-1200 ms) during wakefulness, but no group difference was found in REM sleep. The current dominant hypothesis proposes that alpha rhythms would be involved in the active inhibition of the brain regions not involved in the ongoing brain operation. According to this hypothesis, a more sustained alpha decrease in HR would reflect a longer release of inhibition, suggesting a deeper processing of complex sounds than in LR during wakefulness. A possibility to explain the absence of group difference during sleep is that increase in alpha power in HR may have resulted in awakenings. Our results support this hypothesis since HR experienced more intra sleep wakefulness than LR (30 ± 4 vs. 14 ± 4 min). As a whole our results support the hypothesis of neurophysiological trait differences in high and

  16. Alpha reactivity to first names differs in subjects with high and low dream recall frequency

    PubMed Central

    Ruby, Perrine; Blochet, Camille; Eichenlaub, Jean-Baptiste; Bertrand, Olivier; Morlet, Dominique; Bidet-Caulet, Aurélie

    2013-01-01

    Studies in cognitive psychology showed that personality (openness to experience, thin boundaries, absorption), creativity, nocturnal awakenings, and attitude toward dreams are significantly related to dream recall frequency (DRF). These results suggest the possibility of neurophysiological trait differences between subjects with high and low DRF. To test this hypothesis we compared sleep characteristics and alpha reactivity to sounds in subjects with high and low DRF using polysomnographic recordings and electroencephalography (EEG). We acquired EEG from 21 channels in 36 healthy subjects while they were presented with a passive auditory oddball paradigm (frequent standard tones, rare deviant tones and very rare first names) during wakefulness and sleep (intensity, 50 dB above the subject's hearing level). Subjects were selected as High-recallers (HR, DRF = 4.42 ± 0.25 SEM, dream recalls per week) and Low-recallers (LR, DRF = 0.25 ± 0.02) using a questionnaire and an interview on sleep and dream habits. Despite the disturbing setup, the subjects' quality of sleep was generally preserved. First names induced a more sustained decrease in alpha activity in HR than in LR at Pz (1000–1200 ms) during wakefulness, but no group difference was found in REM sleep. The current dominant hypothesis proposes that alpha rhythms would be involved in the active inhibition of the brain regions not involved in the ongoing brain operation. According to this hypothesis, a more sustained alpha decrease in HR would reflect a longer release of inhibition, suggesting a deeper processing of complex sounds than in LR during wakefulness. A possibility to explain the absence of group difference during sleep is that increase in alpha power in HR may have resulted in awakenings. Our results support this hypothesis since HR experienced more intra sleep wakefulness than LR (30 ± 4 vs. 14 ± 4 min). As a whole our results support the hypothesis of neurophysiological trait differences in high

  17. id="content" class="area">

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    Volume 201, Issue14 (November 2004)

    Articles in the Current Issue:

    Rapid Research Note

    Highly (001)-textured WS2-x films prepared by reactive radio frequency magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Ellmer, K.; Mientus, R.; Seeger, S.; Weiß, V.

    2004-11-01

    Highly (001)-oriented WS2-x films were grown onto oxidized silicon substrates by reactive magnetron sputtering from a metallic tungsten target in argon-hydrogen sulfide mixtures. The best films with respect to the van-der-Waals orientation, i.e. with the (001) planes parallel to the substrate surface, were grown by excitation of the plasma with radio frequency of 27.12 MHz. These films exhibit the largest grains and the lowest film strain. It is shown that this effect is not due to the lower deposition rate at this high excitation frequency. Instead it was found that the lower DC voltage at the sputtering target is advantageous for the film growth since the bombardment of the growing film by highly energetic particles is avoided by this type of plasma excitation.

  18. Research and Development for an Alternative RF Source Using Magnetrons in CEBAF

    NASA Astrophysics Data System (ADS)

    Jacobs, Andrew

    2016-09-01

    At Jefferson Lab, klystrons are currently used as a radiofrequency (RF) power source for the 1497 MHz Continuous Electron Beam Accelerator Facility (CEBAF) Continuous Wave (CW) system. A drop-in replacement for the klystrons in the form of a system of magnetrons is being developed. The klystron DC-RF efficiency at CEBAF is 35-51% while the estimated magnetron efficiency is 80-90%. Thus, the introduction of magnetrons to CEBAF will have enormous benefits in terms of electrical power saving. The primary focus of this project was to characterize a magnetron's frequency pushing and pulling curves at 2.45 GHz with stub tuner and anode current adjustments so that a Low Level RF controller for a new 1.497 GHz magnetron can be built. A Virtual Instrument was created in LabVIEW, and data was taken. The resulting data allowed for the creation of many constant lines of frequency and output power. Additionally, the results provided a characterization of magnetron oven temperature drift over the operation time and the relationship between anode current and frequency. Using these results, the control model of different variables and their feedback or feedforward that affect the frequency pushing and pulling of the magnetron is better developed. Department of Energy, Science Undergraduate Laboratory Internships, and Jefferson Lab.

  19. Highly adherent bioactive glass thin films synthetized by magnetron sputtering at low temperature.

    PubMed

    Stan, G E; Pasuk, I; Husanu, M A; Enculescu, I; Pina, S; Lemos, A F; Tulyaganov, D U; El Mabrouk, K; Ferreira, J M F

    2011-12-01

    Thin (380-510 nm) films of a low silica content bioglass with MgO, B(2)O(3), and CaF(2) as additives were deposited at low-temperature (150°C) by radio-frequency magnetron sputtering onto titanium substrates. The influence of sputtering conditions on morphology, structure, composition, bonding strength and in vitro bioactivity of sputtered bioglass films was investigated. Excellent pull-out adherence (~73 MPa) was obtained when using a 0.3 Pa argon sputtering pressure (BG-a). The adherence declined (~46 MPa) upon increasing the working pressure to 0.4 Pa (BG-b) or when using a reactive gas mixture (~50 MPa). The SBF tests clearly demonstrated strong biomineralization features for all bioglass sputtered films. The biomineralization rate increased from BG-a to BG-b, and yet more for BG-c. A well-crystallized calcium hydrogen phosphate-like phase was observed after 3 and 15 days of immersion in SBF in all bioglass layers, which transformed monotonously into hydroxyapatite under prolonged SBF immersion. Alkali and alkali-earth salts (NaCl, KCl and CaCO(3)) were also found at the surface of samples soaked in SBF for 30 days. The study indicated that features such as composition, structure, adherence and bioactivity of bioglass films can be tailored simply by altering the magnetron sputtering working conditions, proving that this less explored technique is a promising alternative for preparing implant-type coatings.

  20. Tracking the Magnetron Motion in FT-ICR Mass Spectrometry.

    PubMed

    Jertz, Roland; Friedrich, Jochen; Kriete, Claudia; Nikolaev, Evgeny N; Baykut, Gökhan

    2015-08-01

    In Fourier transform ion cyclotron resonance spectrometry (FT-ICR MS) the ion magnetron motion is not usually directly measured, yet its contribution to the performance of the FT-ICR cell is important. Its presence is manifested primarily by the appearance of even-numbered harmonics in the spectra. In this work, the relationship between the ion magnetron motion in the ICR cell and the intensities of the second harmonic signal and its sideband peak in the FT-ICR spectrum is studied. Ion motion simulations show that during a cyclotron motion excitation of ions which are offset to the cell axis, a position-dependent radial drift of the cyclotron center takes place. This radial drift can be directed outwards if the ion is initially offset towards one of the detection electrodes, or it can be directed inwards if the ion is initially offset towards one of the excitation electrodes. Consequently, a magnetron orbit diameter can increase or decrease during a resonant cyclotron excitation. A method has been developed to study this behavior of the magnetron motion by acquiring a series of FT-ICR spectra using varied post-capture delay (PCD) time intervals. PCD is the delay time after the capture of the ions in the cell before the cyclotron excitation of the ion is started. Plotting the relative intensity of the second harmonic sideband peak versus the PCD in each mass spectrum leads to an oscillating "PCD curve". The position and height of minima and maxima of this curve can be used to interpret the size and the position of the magnetron orbit. Ion motion simulations show that an off-axis magnetron orbit generates even-numbered harmonic peaks with sidebands at a distance of one magnetron frequency and multiples of it. This magnetron offset is due to a radial offset of the electric field axis versus the geometric cell axis. In this work, we also show how this offset of the radial electric field center can be corrected by applying appropriate DC correction voltages to the

  1. Theoretical investigation of the dielectric-filled relativistic magnetron

    SciTech Connect

    Wang, Xiaoyu; Fan, Yuwei; Shu, Ting; Shi, Difu

    2016-01-15

    The fundamental mode frequency of a dielectric-filled relativistic magnetron is studied theoretically by the method of the equivalent circuit, and an exact fundamental mode frequency formula is derived. To prove the validity of the theoretical formula, simulation investigation is performed. The simulation results agree well with the theoretical formula, and the relative error does not exceed 3%. The comparative results verify the creditability of the theoretical formula.

  2. Mechanisms of the formation of low spatial frequency LIPSS on Ni/  Ti reactive multilayers

    NASA Astrophysics Data System (ADS)

    Cangueiro, Liliana T.; Cavaleiro, André J.; Morgiel, Jerzy; Vilar, Rui

    2016-09-01

    The present paper aims at investigating the mechanisms of imprinting LIPSS (laser-induced periodic surface structures), arrangements of parallel ripples with a periodicity slightly smaller than the radiation wavelength, on metallic surfaces. To this end, Ni/Ti multi-layered samples produced by magnetron sputtering were textured with LIPSS using a 1030 nm, 560 fs pulse duration laser and pulse frequency of 1 kHz, and the resulting surfaces were investigated by scanning and transmission electron microscopies. The results obtained show that the core of the ripples remains in the solid state during the laser treatment, except for a layer of material about 30 nm thick at the valleys and 65-130 nm thick at the top of the crests, which melts and solidifies forming NiTi with an amorphous structure. A layer of ablation debris composed of amorphous NiTi nanoparticles was redeposited on the LIPSS crests. The results achieved indicate that the periodic variation of the absorbed radiation intensity leads to a variation of the predominant ablation mechanisms and, consequently, of the ablation rate, thus explaining the rippled surface topography. The comparison with theoretical predictions suggests that in the intensity maxima (corresponding to the valleys) the material is removed by liquid spallation, while at its minima (the crests) the predominant material removal mechanism is melting and vaporization. These results support Sipe et al LIPSS formation theory and are in contradiction with the theories that explain the formation of LIPSS by convective fluid flow or self-organized mass transport of a laser-induced instability.

  3. Dynamic phase-control of a rising sun magnetron using modulated and continuous current

    SciTech Connect

    Fernandez-Gutierrez, Sulmer; Browning, Jim; Lin, Ming-Chieh; Smithe, David N.; Watrous, Jack

    2016-01-28

    Phase-control of a magnetron is studied via simulation using a combination of a continuous current source and a modulated current source. The addressable, modulated current source is turned ON and OFF at the magnetron operating frequency in order to control the electron injection and the spoke phase. Prior simulation work using a 2D model of a Rising Sun magnetron showed that the use of 100% modulated current controlled the magnetron phase and allowed for dynamic phase control. In this work, the minimum fraction of modulated current source needed to achieve a phase control is studied. The current fractions (modulated versus continuous) were varied from 10% modulated current to 100% modulated current to study the effects on phase control. Dynamic phase-control, stability, and start up time of the device were studied for all these cases showing that with 10% modulated current and 90% continuous current, a phase shift of 180° can be achieved demonstrating dynamic phase control.

  4. NOVEL TECHNIQUE OF POWER CONTROL IN MAGNETRON TRANSMITTERS FOR INTENSE ACCELERATORS

    SciTech Connect

    Kazakevich, G.; Johnson, R.; Neubauer, M.; Lebedev, V.; Schappert, W.; Yakovlev, V.

    2016-10-21

    A novel concept of a high-power magnetron transmitter allowing dynamic phase and power control at the frequency of locking signal is proposed. The transmitter compensating parasitic phase and amplitude modulations inherent in Superconducting RF (SRF) cavities within closed feedback loops is intended for powering of the intensity-frontier superconducting accelerators. The con- cept uses magnetrons driven by a sufficient resonant (in- jection-locking) signal and fed by the voltage which can be below the threshold of self-excitation. This provides an extended range of power control in a single magnetron at highest efficiency minimizing the cost of RF power unit and the operation cost. Proof-of-principle of the proposed concept demonstrated in pulsed and CW regimes with 2.45 GHz, 1kW magnetrons is discussed here. A conceptual scheme of the high-power transmitter allowing the dynamic wide-band phase and y power controls is presented and discussed.

  5. Reactive hydroxyl radical-driven oral bacterial inactivation by radio frequency atmospheric plasma

    NASA Astrophysics Data System (ADS)

    Kang, Sung Kil; Choi, Myeong Yeol; Koo, Il Gyo; Kim, Paul Y.; Kim, Yoonsun; Kim, Gon Jun; Mohamed, Abdel-Aleam H.; Collins, George J.; Lee, Jae Koo

    2011-04-01

    We demonstrated bacterial (Streptococcus mutans) inactivation by a radio frequency power driven atmospheric pressure plasma torch with H2O2 entrained in the feedstock gas. Optical emission spectroscopy identified substantial excited state •OH generation inside the plasma and relative •OH formation was verified by optical absorption. The bacterial inactivation rate increased with increasing •OH generation and reached a maximum 5-log10 reduction with 0.6% H2O2 vapor. Generation of large amounts of toxic ozone is drawback of plasma bacterial inactivation, thus it is significant that the ozone concentration falls within recommended safe allowable levels with addition of H2O2 vapor to the plasma.

  6. Reactive hydroxyl radical-driven oral bacterial inactivation by radio frequency atmospheric plasma

    SciTech Connect

    Kang, Sung Kil; Lee, Jae Koo; Choi, Myeong Yeol; Koo, Il Gyo; Kim, Paul Y.; Kim, Yoonsun; Kim, Gon Jun; Collins, George J.; Mohamed, Abdel-Aleam H.

    2011-04-04

    We demonstrated bacterial (Streptococcus mutans) inactivation by a radio frequency power driven atmospheric pressure plasma torch with H{sub 2}O{sub 2} entrained in the feedstock gas. Optical emission spectroscopy identified substantial excited state OH generation inside the plasma and relative OH formation was verified by optical absorption. The bacterial inactivation rate increased with increasing OH generation and reached a maximum 5-log{sub 10} reduction with 0.6%H{sub 2}O{sub 2} vapor. Generation of large amounts of toxic ozone is drawback of plasma bacterial inactivation, thus it is significant that the ozone concentration falls within recommended safe allowable levels with addition of H{sub 2}O{sub 2} vapor to the plasma.

  7. Automation of high-frequency sampling of environmental waters for reactive species

    NASA Astrophysics Data System (ADS)

    Kim, H.; Bishop, J. K.; Wood, T.; Fung, I.; Fong, M.

    2011-12-01

    Trace metals, particularly iron and manganese, play a critical role in some ecosystems as a limiting factor to determine primary productivity, in geochemistry, especially redox chemistry as important electron donors and acceptors, and in aquatic environments as carriers of contaminant transport. Dynamics of trace metals are closely related to various hydrologic events such as rainfall. Storm flow triggers dramatic changes of both dissolved and particulate trace metals concentrations and affects other important environmental parameters linked to trace metal behavior such as dissolved organic carbon (DOC). To improve our understanding of behaviors of trace metals and underlying processes, water chemistry information must be collected for an adequately long period of time at higher frequency than conventional manual sampling (e.g. weekly, biweekly). In this study, we developed an automated sampling system to document the dynamics of trace metals, focusing on Fe and Mn, and DOC for a multiple-year high-frequency geochemistry time series in a small catchment, called Rivendell located at Angelo Coast Range Reserve, California. We are sampling ground and streamwater using the automated sampling system in daily-frequency and the condition of the site is substantially variable from season to season. The ranges of pH of ground and streamwater are pH 5 - 7 and pH 7.8 - 8.3, respectively. DOC is usually sub-ppm, but during rain events, it increases by an order of magnitude. The automated sampling system focuses on two aspects- 1) a modified design of sampler to improve sample integrity for trace metals and DOC and 2) remote controlling system to update sampling volume and timing according to hydrological conditions. To maintain sample integrity, the developed method employed gravity filtering using large volume syringes (140mL) and syringe filters connected to a set of polypropylene bottles and a borosilicate bottle via Teflon tubing. Without filtration, in a few days, the

  8. Effect of SiNx diffusion barrier thickness on the structural properties and photocatalytic activity of TiO2 films obtained by sol–gel dip coating and reactive magnetron sputtering

    PubMed Central

    Aubry, Eric; Chaoui, Nouari; Robert, Didier

    2015-01-01

    Summary We investigate the effect of the thickness of the silicon nitride (SiNx) diffusion barrier on the structural and photocatalytic efficiency of TiO2 films obtained with different processes. We show that the structural and photocatalytic efficiency of TiO2 films produced using soft chemistry (sol–gel) and physical methods (reactive sputtering) are affected differentially by the intercalating SiNx diffusion barrier. Increasing the thickness of the SiNx diffusion barrier induced a gradual decrease of the crystallite size of TiO2 films obtained by the sol–gel process. However, TiO2 obtained using the reactive sputtering method showed no dependence on the thickness of the SiNx barrier diffusion. The SiNx barrier diffusion showed a beneficial effect on the photocatalytic efficiency of TiO2 films regardless of the synthesis method used. The proposed mechanism leading to the improvement in the photocatalytic efficiency of the TiO2 films obtained by each process was discussed. PMID:26665074

  9. Effect of SiN x diffusion barrier thickness on the structural properties and photocatalytic activity of TiO2 films obtained by sol-gel dip coating and reactive magnetron sputtering.

    PubMed

    Ghazzal, Mohamed Nawfal; Aubry, Eric; Chaoui, Nouari; Robert, Didier

    2015-01-01

    We investigate the effect of the thickness of the silicon nitride (SiN x ) diffusion barrier on the structural and photocatalytic efficiency of TiO2 films obtained with different processes. We show that the structural and photocatalytic efficiency of TiO2 films produced using soft chemistry (sol-gel) and physical methods (reactive sputtering) are affected differentially by the intercalating SiN x diffusion barrier. Increasing the thickness of the SiN x diffusion barrier induced a gradual decrease of the crystallite size of TiO2 films obtained by the sol-gel process. However, TiO2 obtained using the reactive sputtering method showed no dependence on the thickness of the SiN x barrier diffusion. The SiN x barrier diffusion showed a beneficial effect on the photocatalytic efficiency of TiO2 films regardless of the synthesis method used. The proposed mechanism leading to the improvement in the photocatalytic efficiency of the TiO2 films obtained by each process was discussed.

  10. Model for designing planar magnetron cathodes

    SciTech Connect

    Garcia, M.

    1997-09-30

    This report outlines an analytical model of the distribution of plasma in the cathode fall of a planar magnetron cathode. Here I continue commentary on previous work, and introduce an ion sheath model to describe the discharge dark space below the magnetron halo.

  11. Multi-cathode unbalanced magnetron sputtering systems

    NASA Technical Reports Server (NTRS)

    Sproul, William D.

    1991-01-01

    Ion bombardment of a growing film during deposition is necessary in many instances to ensure a fully dense coating, particularly for hard coatings. Until the recent advent of unbalanced magnetron (UBM) cathodes, reactive sputtering had not been able to achieve the same degree of ion bombardment as other physical vapor deposition processes. The amount of ion bombardment of the substrate depends on the plasma density at the substrate, and in a UBM system the amount of bombardment will depend on the degree of unbalance of the cathode. In multi-cathode systems, the magnetic fields between the cathodes must be linked to confine the fast electrons that collide with the gas atoms. Any break in this linkage results in electrons being lost and a low plasma density. Modeling of the magnetic fields in a UBM cathode using a finite element analysis program has provided great insight into the interaction between the magnetic fields in multi-cathode systems. Large multi-cathode systems will require very strong magnets or many cathodes in order to maintain the magnetic field strength needed to achieve a high plasma density. Electromagnets offer the possibility of independent control of the plasma density. Such a system would be a large-scale version of an ion beam enhanced deposition (IBED) system, but, for the UBM system where the plasma would completely surround the substrate, the acronym IBED might now stand for Ion Blanket Enhanced Deposition.

  12. Chemical mechanical polishing characteristics of ITO thin film prepared by RF magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Lee, Kang-Yeon; Choi, Gwon-Woo; Kim, Yong-Jae; Choi, Youn-Ok; Kim, Nam-Oh

    2012-02-01

    Indium-tin-oxide (ITO) thin films have attracted intensive interest because of their unique properties of good conductivity, high optical transmittance over the visible region and easy patterning ability. ITO thin films have found many applications in anti-static coatings, thermal heaters, solar cells, flat panel displays (FPDs), liquid crystal displays (LCDs), electroluminescent devices, sensors and organic light-emitting diodes (OLEDs). ITO thin films are generally fabricated by using various methods, such as spraying, chemical vapor deposition (CVD), evaporation, electron gun deposition, direct current electroplating, high frequency sputtering, and reactive sputtering. In this research, ITO films were grown on glass substrates by using a radio-frequency (RF) magnetron sputtering method. In order to achieve a high transmittance and a low resistivity, we examined the various film deposition conditions, such as substrate temperature, working pressure, annealing temperature, and deposition time. Next, in order to improve the surface quality of the ITO thin films, we performed a chemical mechanical polishing (CMP) with different process parameters and compared the electrical and the optical properties of the polished ITO thin films. The best CMP conditions with a high removal rate, low nonuniformity, low resistivity and high transmittance were as follows: platen speed, head speed, polishing time, and slurry flow rate of 30 rpm, 30 rpm, 60 sec, and 60 ml/min, respectively.

  13. Undoped InOx films deposited by radio frequency plasma enhanced reactive thermal evaporation at room temperature: importance of substrate.

    PubMed

    Parreira, P; Lavareda, G; Valente, J; Nunes, F T; Amaral, A; de Carvalho, C Nunes

    2010-04-01

    Conductive and transparent undoped thin films of indium oxide (InOx ), 120 nm average thick, were deposited by radio frequency plasma enhanced reactive thermal evaporation (rf-PERTE) of indium in the presence of oxygen at room temperature. Several substrates were used in order to study their influence on the main properties of these films: alkali free (AF) glass, fused silica, crystalline silicon and polyethylene terephthalate (PET). Surface morphology of the InOx films as a function of the substrates was observed by SEM and showed that the undoped InOx films obtained are nanostructured. For the c-Si substrate, InOx films with increased grain size are obtained, induced by the crystalline substrate. Films deposited on fused silica and AF glass substrates show a nano-grainy surface with similar surface morphologies. The InOx films deposited on AF glass show the highest values of both: electrical conductivity of about 1100 (omega cm)(-1) and visible transmittance of 85%. The substrate has a greater influence on the surface morphology of the films when a polymer (PET) is used. InOx films deposited on PET show a decrease in the electrical conductivity (90 (omega cm)(-1)) and a slight decrease in the average visible transmittance (78%).

  14. Do Productive Activities Reduce Inflammation in Later Life? Multiple Roles, Frequency of Activities, and C-Reactive Protein

    PubMed Central

    Kim, Seoyoun; Ferraro, Kenneth F.

    2014-01-01

    Purpose of the Study: The study investigates whether productive activities by older adults reduce bodily inflammation, as indicated by C-reactive protein (CRP), a biomeasure associated with the risk of cardiovascular diseases. Design and Methods: The study uses a representative survey of adults aged 57–85 from the National Social Life, Health, and Aging Project (N = 1,790). Linear regression models were used to analyze the effects of multiple roles (employment, volunteering, attending meetings, and caregiving) and the frequency of activity within each role on log values of CRP concentration (mg/L) drawn from assayed blood samples. Results: Number of roles for productive activities was associated with lower levels of CRP net of chronic conditions, lifestyle factors, and socioeconomic resources. When specific types of activity were examined, volunteering manifested the strongest association with lower levels of inflammation, particularly in the 70+ group. There was no evidence that frequent engagement in volunteer activity was associated with heightened inflammation. Implications: Productive activities—and frequent volunteering in particular—may protect individuals from inflammation that is associated with increased risk of hypertension and cardiovascular disease. PMID:23969258

  15. 3-D Printed High Power Microwave Magnetrons

    NASA Astrophysics Data System (ADS)

    Jordan, Nicholas; Greening, Geoffrey; Exelby, Steven; Gilgenbach, Ronald; Lau, Y. Y.; Hoff, Brad

    2015-11-01

    The size, weight, and power requirements of HPM systems are critical constraints on their viability, and can potentially be improved through the use of additive manufacturing techniques, which are rapidly increasing in capability and affordability. Recent experiments on the UM Recirculating Planar Magnetron (RPM), have explored the use of 3-D printed components in a HPM system. The system was driven by MELBA-C, a Marx-Abramyan system which delivers a -300 kV voltage pulse for 0.3-1.0 us, with a 0.15-0.3 T axial magnetic field applied by a pair of electromagnets. Anode blocks were printed from Water Shed XC 11122 photopolymer using a stereolithography process, and prepared with either a spray-coated or electroplated finish. Both manufacturing processes were compared against baseline data for a machined aluminum anode, noting any differences in power output, oscillation frequency, and mode stability. Evolution and durability of the 3-D printed structures were noted both visually and by tracking vacuum inventories via a residual gas analyzer. Research supported by AFOSR (grant #FA9550-15-1-0097) and AFRL.

  16. A Plasma Lens for Magnetron Sputtering

    SciTech Connect

    Anders, Andre; Brown, Jeff

    2010-11-30

    A plasma lens, consisting of a solenoid and potential-defining ring electrodes, has been placed between a magnetron and substrates to be coated. Photography reveals qualitative information on excitation, ionization, and the transport of plasma to the substrate.

  17. EMI shielding using composite materials with two sources magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Ziaja, J.; Jaroszewski, M.; Lewandowski, M.

    2016-02-01

    In this study, the preparation composite materials for electromagnetic shields using two sources magnetron sputtering DC-M is presented. A composite material was prepared by coating a nonwoven polypropylene metallic layer in sputtering process of targets Ti (purity 99%) and brass alloy MO58 (58%Cu, 40%Zn, 2%Pb) and ϕ diameter targets = 50 mm, under argon atmosphere. The system with magnetron sputtering sources was powered using switch-mode power supply DPS (Dora Power System) with a maximum power of 16 kW and a maximum voltage of 1.2 kV with group frequency from 50 Hz to 5 kHz. The influence of sputtering time of individual targets on the value of the EM field attenuation SE [dB] was investigated for the following supply conditions: pressure pp = 2x10-3 Torr, sputtering power P = 750 W, the time of applying a layer t = 5 min, group frequency fg = 2 kHz, the frequency of switching between targets fp = 1 Hz.

  18. Initial deposition of calcium phosphate ceramic on polystyrene and polytetrafluoroethylene by rf magnetron sputtering deposition

    NASA Astrophysics Data System (ADS)

    Feddes, B.; Wolke, J. G. C.; Jansen, J. A.; Vredenberg, A. M.

    2003-03-01

    Calcium phosphate (CaP) coatings can be applied to improve the biological performance of polymeric medical implants. A strong interfacial bond between ceramic and polymer is required for clinical applications. Because the chemical structure of an interface plays an important role in the adhesion of a coating, we studied the formation of the interface between CaP and polystyrene (PS) and polytetrafluoroethylene (PTFE). The coating was deposited in a radio frequency (rf) magnetron sputtering deposition system. Prior to the deposition, some samples received an oxygen plasma pretreatment. We found that the two substrates show a strongly different reactivity towards CaP. On PS a phosphorus and oxygen enrichment is present at the interface. This is understood from POx complexes that are able to bind to the PS. The effects of the plasma pretreatment are overruled by the deposition process itself. On PTFE, a calcium enrichment and an absence of phosphorus is found at the interface. The former is the result of CaF2-like material being formed at the interface. The latter may be the result of phosphorus reacting with escaping fluorine to a PF3 molecule, which than escapes from the material as a gas molecule. We found that the final structure of the interface is mostly controlled by the bombardment of energetic particles escaping either from the plasma or from the sputtering target. The work described here can be used to understand and improve the adhesion of CaP coatings deposited on medical substrates.

  19. Synthesis of Tantalum-Doped Tin Oxide Thin Films by Magnetron Sputtering for Photovoltaic Applications

    NASA Astrophysics Data System (ADS)

    Nguyen, Ngoc Minh; Luu, Manh Quynh; Nguyen, Minh Hieu; Nguyen, Duy Thien; Bui, Van Diep; Truong, Thanh Tu; Pham, Van Thanh; Nguyen-Tran, Thuat

    2017-01-01

    Tantalum-doped tin oxide transparent conductive thin films were deposited on glass substrates by radio frequency and direct current reactive magnetron co-sputtering methods in an argon and oxygen environment. Optimization of the thin films for photovoltaic applications was performed using a dimensionless figure of merit by combining electrical and transparency properties. The optimized thin film showed a weight-averaged transmittance of 83%, a band gap value of 3.2 eV, resistivity of 5.2 × 10-3 Ω cm, and bulk carrier concentration of 1.2 × 1020 cm-3. The lowest resistivity among all films was 2.1 × 10-3 Ω cm, corresponding to a weight-averaged transmittance of 62%. The optimized deposition condition was carried out by co-sputtering on heated substrates at 270°C. Thin films deposited under this optimized condition were applied for our perovskite solar cells, and demonstrated promising power conversion efficiency.

  20. Evidence for an Inducible Repair-Recombination System in the Female Germ Line of Drosophila Melanogaster. III. Correlation between Reactivity Levels, Crossover Frequency and Repair Efficiency

    PubMed Central

    Laurencon, A.; Gay, F.; Ducau, J.; Bregliano, J. C.

    1997-01-01

    We previously reported evidence that the so-called reactivity level, a peculiar cellular state of oocytes that regulates the frequency of transposition of I factor, a LINE element-like retrotransposon, might be one manifestation of a DNA repair system. In this article, we report data showing that the reactivity level is correlated with the frequency of crossing over, at least on the X chromosome and on the pericentromeric region of the third chromosome. Moreover, a check for X-chromosome losses and recessive lethals produced after gamma irradiation in flies with different reactivity levels, but common genetic backgrounds, brings more precise evidence for the relationship between reactivity levels and DNA repair. Those results support the existence of a repair-recombination system whose efficiency is modulated by endogenous and environmental factors. The implications of this biological system in connecting genomic variability and environment may shed new lights on adaptative mechanisms. We propose to call it VAMOS for variability modulation system. PMID:9258678

  1. Precision vector control of a superconducting RF cavity driven by an injection locked magnetron

    DOE PAGES

    Chase, Brian; Pasquinelli, Ralph; Cullerton, Ed; ...

    2015-03-01

    The technique presented in this paper enables the regulation of both radio frequency amplitude and phase in narrow band devices such as a Superconducting RF (SRF) cavity driven by constant power output devices i.e. magnetrons [1]. The ability to use low cost high efficiency magnetrons for accelerator RF power systems, with tight vector regulation, presents a substantial cost savings in both construction and operating costs - compared to current RF power system technology. An operating CW system at 2.45 GHz has been experimentally developed. Vector control of an injection locked magnetron has been extensively tested and characterized with a SRFmore » cavity as the load. Amplitude dynamic range of 30 dB, amplitude stability of 0.3% r.m.s, and phase stability of 0.26 degrees r.m.s. has been demonstrated.« less

  2. Precision vector control of a superconducting RF cavity driven by an injection locked magnetron

    SciTech Connect

    Chase, Brian; Pasquinelli, Ralph; Cullerton, Ed; Varghese, Philip

    2015-03-01

    The technique presented in this paper enables the regulation of both radio frequency amplitude and phase in narrow band devices such as a Superconducting RF (SRF) cavity driven by constant power output devices i.e. magnetrons [1]. The ability to use low cost high efficiency magnetrons for accelerator RF power systems, with tight vector regulation, presents a substantial cost savings in both construction and operating costs - compared to current RF power system technology. An operating CW system at 2.45 GHz has been experimentally developed. Vector control of an injection locked magnetron has been extensively tested and characterized with a SRF cavity as the load. Amplitude dynamic range of 30 dB, amplitude stability of 0.3% r.m.s, and phase stability of 0.26 degrees r.m.s. has been demonstrated.

  3. The process of growing Cr2O3 thin films on α-Al2O3 substrates at low temperature by r.f. magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Gao, Yin; Leiste, Harald; Stueber, Michael; Ulrich, Sven

    2017-01-01

    Cr2O3 thin films with a thickness of 180 nm are grown on c-plane α-Al2O3 (0001) single crystal substrates at a substrate temperature of 320 °C by non-reactive radio frequency magnetron sputtering. Phase formation and composition are characterized by X-ray diffraction (XRD) and Raman spectroscopy analysis. Additional information such as in-plane and out-of-plane lattice parameters, strain relaxation and texture are obtained by reciprocal space mappings (RSMs) and pole figure measurements. Transmission electron microscopy (TEM) has been carried out in order to study the microstructure and further confirm the orientation and epitaxial relationship between films and substrates.

  4. Sum-Frequency Generation Spectroscopy for Studying Organic Layers at Water-Air Interfaces: Microlayer Monitoring and Surface Reactivity

    NASA Astrophysics Data System (ADS)

    Laß, Kristian; Kleber, Joscha; Bange, Hermann; Friedrichs, Gernot

    2015-04-01

    The sea surface microlayer, according to commonly accepted terminology, comprises the topmost millimetre of the oceanic water column. It is often enriched with organic matter and is directly influenced by sunlight exposure and gas exchange with the atmosphere, hence making it a place for active biochemistry and photochemistry as well as for heterogeneous reactions. In addition, surface active material either is formed or accumulates directly at the air-water interface and gives rise to very thin layers, sometimes down to monomolecular thickness. This "sea surface nanolayer" determines the viscoelastic properties of the seawater surface and thus may impact the turbulent air-sea gas exchange rates. To this effect, this small scale layer presumably plays an important role for large scale changes of atmospheric trace gas concentrations (e.g., by modulating the ocean carbon sink characteristics) with possible implications for coupled climate models. To date, detailed knowledge about the composition, structure, and reactivity of the sea surface nanolayer is still scarce. Due to its small vertical dimension and the small amount of material, this surfactant layer is very difficult to separate and analyse. A way out is the application of second-order nonlinear optical methods, which make a direct surface-specific and background-free detection of this interfacial layer possible. In recent years, we have introduced the use of vibrational sum frequency generation (VSFG) spectroscopy to gain insight into natural and artificial organic monolayers at the air-water interface. In this contribution, the application of VSFG spectroscopy for the analysis of the sea surface nanolayer will be illustrated. Resulting spectra are interpreted in terms of layer composition and surfactant classes, in particular with respect to carbohydrate-containing molecules such as glycolipids. The partitioning of the detected surfactants into soluble and non-soluble ("wet" and "dry") surfactants will be

  5. On Tomonaga's theory of split-anode magnetrons

    NASA Astrophysics Data System (ADS)

    Dittrich, Walter

    2016-06-01

    This article offers a review of the history of radar research and its application in the 20th century. After describing the wartime work of Sin-Itiro Tomonaga and his theory of the cavity magnetron, we formulate the equations of motion of an electron in a cavity magnetron using action-angle variables. This means following the electron's path on its way from a cylindrical cathode moving toward a co-axial cylindrical anode in presence of a uniform magnetic field parallel to the common axis. After analyzing the situation without coupling to an external oscillatory electric field, we employ methods of canonical perturbation theory to find the resonance condition between the frequencies of the free theory ωr, ωϕ and the applied perturbing oscillatory frequency ω. A long-time averaging process will then eliminate the periodic terms in the equation for the now time-dependent action-angle variables. The terms that are no longer periodic will cause secular changes so that the canonical action-angle variables (J, δ) change in a way that the path of the electron will deform gradually so that it can reach the anode. How the ensemble of the initially randomly distributed electrons forms spokes and how their energy is conveyed to the cavity-field oscillation is the main focus of this article. Some remarks concerning the importance of results in QED and the invention of radar theory and application conclude the article.

  6. Stability of Brillouin flow in planar, conventional, and inverted magnetrons

    SciTech Connect

    Simon, D. H.; Lau, Y. Y.; Greening, G.; Wong, P.; Gilgenbach, R. M.; Hoff, B. W.

    2015-08-15

    The Brillouin flow is the prevalent flow in crossed-field devices. We systematically study its stability in the conventional, planar, and inverted magnetron geometry. To investigate the intrinsic negative mass effect in Brillouin flow, we consider electrostatic modes in a nonrelativistic, smooth bore magnetron. We found that the Brillouin flow in the inverted magnetron is more unstable than that in a planar magnetron, which in turn is more unstable than that in the conventional magnetron. Thus, oscillations in the inverted magnetron may startup faster than the conventional magnetron. This result is consistent with simulations, and with the negative mass property in the inverted magnetron configuration. Inclusion of relativistic effects and electromagnetic effects does not qualitatively change these conclusions.

  7. Anisotropies in magnetron sputtered carbon nitride thin films

    NASA Astrophysics Data System (ADS)

    Hellgren, Niklas; Johansson, Mats P.; Broitman, Esteban; Hultman, Lars; Sundgren, Jan-Eric

    2001-04-01

    Carbon nitride CNx (0⩽x⩽0.35) thin films, deposited by reactive dc magnetron sputtering in Ar/N2 discharges have been studied with respect to microstructure using electron microscopy, and elastic modulus using nanoindentation and surface acoustic wave analyses. For growth temperature of 100 °C, the films were amorphous, and with an isotropic Young's modulus of ˜170-200 GPa essentially unaffected by the nitrogen fraction. The films grown at elevated temperatures (350-550 °C) show anisotropic mechanical properties due to a textured microstructure with standing basal planes, as observed from measuring the Young's modulus in different directions. The modulus measured in the plane of the film was ˜60-80 GPa, while in the vertical direction the modulus increased considerably from ˜25 to ˜200 GPa as the nitrogen content was increased above ˜15 at. %.

  8. Analysis of peer-to-peer locking of magnetrons

    SciTech Connect

    Pengvanich, P.; Lau, Y. Y.; Cruz, E.; Gilgenbach, R. M.; Hoff, B.; Luginsland, J. W.

    2008-10-15

    The condition for mutual, or peer-to-peer, locking of two magnetrons is derived. This condition reduces to Adler's classical phase-locking condition in the limit where one magnetron becomes the 'master' and the other becomes the 'slave.' The formulation is extended to the peer-to-peer locking of N magnetrons, under the assumption that the electromagnetic coupling among the N magnetrons is modeled by an N-port network.

  9. Magnetron surface coil for brain MR imaging.

    PubMed

    Rodríguez, Alfredo O

    2006-08-01

    A resonator surface coil was developed for magnetic resonance imaging of the brain and tested on a clinical imager. This resonator design was based on the cavity magnetron with an 8 slot-and-hole configuration. High-resolution brain images were obtained from a water-filled phantom and from a healthy volunteer brain. To compare coil performance, SNR-vs.-depth plots were computed for a single-loop coil and the magnetron prototype from phantom images. These experimentally acquired profiles show an important improvement in SNR. Thus, the magnetron surface coil can generate brain images with a high resolution and penetration capacity. The high sensitivity of this coil makes it a good candidate to be used in multicoil imaging sequences.

  10. Tumor- and Neoantigen-Reactive T-cell Receptors Can Be Identified Based on Their Frequency in Fresh Tumor.

    PubMed

    Pasetto, Anna; Gros, Alena; Robbins, Paul F; Deniger, Drew C; Prickett, Todd D; Matus-Nicodemos, Rodrigo; Douek, Daniel C; Howie, Bryan; Robins, Harlan; Parkhurst, Maria R; Gartner, Jared; Trebska-McGowan, Katarzyna; Crystal, Jessica S; Rosenberg, Steven A

    2016-09-02

    Adoptive transfer of T cells with engineered T-cell receptor (TCR) genes that target tumor-specific antigens can mediate cancer regression. Accumulating evidence suggests that the clinical success of many immunotherapies is mediated by T cells targeting mutated neoantigens unique to the patient. We hypothesized that the most frequent TCR clonotypes infiltrating the tumor were reactive against tumor antigens. To test this hypothesis, we developed a multistep strategy that involved TCRB deep sequencing of the CD8(+)PD-1(+) T-cell subset, matching of TCRA-TCRB pairs by pairSEQ and single-cell RT-PCR, followed by testing of the TCRs for tumor-antigen specificity. Analysis of 12 fresh metastatic melanomas revealed that in 11 samples, up to 5 tumor-reactive TCRs were present in the 5 most frequently occurring clonotypes, which included reactivity against neoantigens. These data show the feasibility of developing a rapid, personalized TCR-gene therapy approach that targets the unique set of antigens presented by the autologous tumor without the need to identify their immunologic reactivity. Cancer Immunol Res; 4(9); 734-43. ©2016 AACR.

  11. Characterization and optimization of the magnetron directional amplifier

    NASA Astrophysics Data System (ADS)

    Hatfield, Michael Craig

    Many applications of microwave wireless power transmission (WPT) are dependent upon a high-powered electronically-steerable phased array composed of many radiating modules. The phase output from the high-gain amplifier in each module must be accurately controlled if the beam is to be properly steered. A highly reliable, rugged, and inexpensive design is essential for making WPT applications practical. A conventional microwave oven magnetron may be combined with a ferrite circulator and other external circuitry to create such a system. By converting it into a two-port amplifier, the magnetron is capable of delivering at least 30 dB of power gain while remaining phase-locked to the input signal over a wide frequency range. The use of the magnetron in this manner is referred to as a MDA (Magnetron Directional Amplifier). The MDA may be integrated with an inexpensive slotted waveguide array (SWA) antenna to form the Electronically-Steerable Phased Array Module (ESPAM). The ESPAM provides a building block approach to creating phased arrays for WPT. The size and shape of the phased array may be tailored to satisfy a diverse range of applications. This study provided an in depth examination into the capabilities of the MDA/ESPAM. The basic behavior of the MDA was already understood, as well as its potential applicability to WPT. The primary objective of this effort was to quantify how well the MDA could perform in this capacity. Subordinate tasks included characterizing the MDA behavior in terms of its system inputs, optimizing its performance, performing sensitivity analyses, and identifying operating limitations. A secondary portion of this study examined the suitability of the ESPAM in satisfying system requirements for the solar power satellite (SPS). Supporting tasks included an analysis of SPS requirements, modeling of the SWA antenna, and the demonstration of a simplified phased array constructed of ESPAM elements. The MDA/ESPAM is well suited for use as an

  12. Recent Operation of the FNAL Magnetron H- Ion Source

    SciTech Connect

    Karns, Patrick R.; Bollinger, D. S.; Sosa, A.

    2016-09-06

    This paper will detail changes in the operational paradigm of the Fermi National Accelerator Laboratory (FNAL) magnetron H- ion source due to upgrades in the accelerator system. Prior to November of 2012 the H- ions for High Energy Physics (HEP) experiments were extracted at ~18 keV vertically downward into a 90 degree bending magnet and accelerated through a Cockcroft-Walton accelerating column to 750 keV. Following the upgrade in the fall of 2012 the H- ions are now directly extracted from a magnetron at 35 keV and accelerated to 750 keV by a Radio Frequency Quadrupole (RFQ). This change in extraction energy as well as the orientation of the ion source required not only a redesign of the ion source, but an updated understanding of its operation at these new values. Discussed in detail are the changes to the ion source timing, arc discharge current, hydrogen gas pressure, and cesium delivery system that were needed to maintain consistent operation at >99% uptime for HEP, with an increased ion source lifetime of over 9 months.

  13. Magnetron Sputtered Molybdenum Oxide for Application in Polymers Solar Cells

    NASA Astrophysics Data System (ADS)

    Sendova-Vassileva, M.; Dikov, Hr; Vitanov, P.; Popkirov, G.; Gergova, R.; Grancharov, G.; Gancheva, V.

    2016-10-01

    Thin films of molybdenum oxide were deposited by radio frequency (RF) magnetron sputtering in Ar from a MoO3 target at different deposition power on glass and silicon substrates. The thickness of the films was determined by profilometer measurements and by ellipsometry. The films were annealed in air at temperatures between 200 and 400°C in air. The optical transmission and reflection spectra were measured. The conductivity of the as deposited and annealed films was determined. The crystal structure was probed by Raman spectroscopy. The oxidation state of the surface was studied by X-ray photoelectron spectroscopy (XPS) spectroscopy. The deposition technique described above was used to experiment with MoOx as a hole transport layer (HTL) in polymer solar cells with bulk hetrojunction active layer, deposited by spin coating. The performance of these layers was compared with poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS), which is the standard material used in this role. The measured current-voltage characteristics of solar cells with the structure glass/ITO/HTL/Poly(3-hexyl)thiophene (P3HT):[6,6]-phenyl-C61- butyric acid methyl ester (PCBM)/Al demonstrate that the studied MoOx layer is a good HTL and leads to comparable characteristics to those with PEDOT:PSS. On the other hand the deposition by magnetron sputtering guarantees reliable and repeatable HTLs.

  14. A Critical Precursor Frequency of Donor-Reactive CD4+ T Cell Help is Required for CD8+ T Cell-Mediated CD28/CD154-Independent Rejection

    PubMed Central

    Ford, Mandy L.; Wagener, Maylene E.; Hanna, Samantha S.; Pearson, Thomas C.; Kirk, Allan D.; Larsen, Christian P.

    2008-01-01

    Antigen-specific precursor frequency is increasingly being appreciated as an important factor in determining the kinetics, magnitude, and degree of differentiation of T cell responses, and recently was found to play a critical role in determining the relative requirement of CD8+ T cells for CD28- and CD154-mediated costimulatory signals during transplantation. We addressed the possibility that variations in CD4+ T cell precursor frequency following transplantation might affect CD4+ T cell proliferation, effector function, and provision of help for donor-reactive B cell and CD8+ T cell responses. Using a transgenic model system wherein increasing frequencies of donor-reactive CD4+ T cells were transferred into skin graft recipients, we observed that a critical CD4+ T cell threshold precursor frequency was necessary to provide help following blockade of the CD28 and CD154 costimulatory pathways, as measured by increased B cell and CD8+ T cell responses and precipitation of graft rejection. In contrast to high-frequency CD8+ T cell responses, this effect was observed even though the proliferative and cytokine responses of Ag-specific CD4+ T cells were inhibited. Thus, we conclude that an initial high frequency of donor-reactive CD4+ T cells uncouples T cell proliferative and effector cytokine production from the provision of T cell help. This is an author-produced version of a manuscript accepted for publication in The Journal of Immunology (The JI). The American Association of Immunologists, Inc. (AAI), publisher of The JI, holds the copyright to this manuscript. This version of the manuscript has not yet been copyedited or subjected to editorial proofreading by The JI; hence, it may differ from the final version published in The JI (online and in print). AAI (The JI) is not liable for errors or omissions in this author-produced version of the manuscript or in any version derived from it by the U.S. National Institutes of Health or any other third party. The final

  15. The Development and Application of the Magnetron,

    DTIC Science & Technology

    1982-03-31

    of *medicine. The power of the magnetron used is from several tens of watts to several hundred watts. Microwave physiotherapy has been used in...clinical practice for the fast cure of arthritis , rheumatism and the subsidence of swelling. Therapeutic results have been excellent. In recent years

  16. Low frequency sonochemical synthesis of nanoporous amorphous manganese dioxide (MnO{sub 2}) and adsorption of remazol reactive dye

    SciTech Connect

    Hasan, Siti Zubaidah; Yusop, Muhammad Rahimi; Othman, Mohamed Rozali

    2015-09-25

    Nanoporous amorphous-MnO{sub 2} was synthesized by sonochemical process (sonication) on the solid manganese (II) acetate tetrahydrate (Mn(CH{sub 3}COO){sub 2}.4H{sub 2}O) in 0.1 M KMnO{sub 4}. The product was characterized by X-ray diffraction (XRD), morphology of the material was scanned by Field Emission Scanning Electron Microscopy (FE-SEM) and absorptions of MnO{sub 2} bonding was characterized by Fourier Transform Infra-Red Spectrometer (FT-IR). Remazol reactive dye or Red 3BS, was used in the adsorption study using nanoporous amorphous-MnO{sub 2}. In batch experiment, 10 ppm of Remazol reactive dye was used and experiment was carried out at room temperature. Adsorption of Remazol dye on 0.2g synthesized nanoporous amorphous-MnO{sub 2} showed 99 – 100% decolorization.

  17. Power Supply to Drive a Magnetron for PFC Gas Resolution

    NASA Astrophysics Data System (ADS)

    Iwabuki, Hiroyasu; Iwata, Akihiko; Yoshiyasu, Hajimu

    A power supply to drive a magnetron for a PFC gas resolution has been developed. The power supply (ratings 5kV, 1A) is composed of a full bridge inverter and a voltage doubler rectifier circuit. The characteristics of the current and electric power of a magnetron with the non-linear load were analyzed. As a result, it was found that the magnetron power and the magnetron peak current are approximately linear to the pulse width when the reactor, which controls the current of magnetron, was inserted in the inverter output. We constructed a trial power supply to drive magnetron. It was confirmed that the trial power supply could continuously control the magnetron output up to 3.5kW. The PFC gas resolution efficiency with microwave plasma is larger than the silent discharge method. Therefore we can expect the realization of a small, highly efficient gas resolution device using microwave plasma.

  18. Bioactivity and hemocompatibility study of amorphous hydrogenated carbon coatings produced by pulsed magnetron discharge.

    PubMed

    Lopez-Santos, C; Colaux, J L; Laloy, J; Fransolet, M; Mullier, F; Michiels, C; Dogné, J-M; Lucas, S

    2013-06-01

    Literature contains very few data about the potential biomedical application of amorphous hydrogenated carbon (a-C:H) thin films deposited by reactive pulsed magnetron discharge even so it is one of the most scalable plasma deposition technique. In this article, we show that such a C2H2 pulsed magnetron plasma produces high quality coating with good hemocompatibility and bioactive response: no effect on hemolysis and hemostasis were observed, and proliferation of various cell types such as endothelial, fibroblast, and osteoblast-like cells was not affected when the deposition conditions were varied. Cell growth on a-C:H coatings is proposed to take place by a two-step process: the initial cell contact is affected by the smooth topography of the a-C:H coatings, whereas the polymeric-like structure, together with a moderate hydrophilicity and a high hydrogen content, directs the posterior cell spreading while preserving the hemocompatible behavior.

  19. Facility for combined in situ magnetron sputtering and soft x-ray magnetic circular dichroism

    SciTech Connect

    Telling, N. D.; Laan, G. van der; Georgieva, M. T.; Farley, N. R. S.

    2006-07-15

    An ultrahigh vacuum chamber that enables the in situ growth of thin films and multilayers by magnetron sputtering techniques is described. Following film preparation, x-ray absorption spectroscopy (XAS) and x-ray magnetic circular dichroism (XMCD) measurements are performed by utilizing an in vacuum electromagnet. XMCD measurements on sputtered thin films of Fe and Co yield spin and orbital moments that are consistent with those obtained previously on films measured in transmission geometry and grown in situ by evaporation methods. Thin films of FeN prepared by reactive sputtering are also examined and reveal an apparent enhancement in the orbital moment for low N content samples. The advantages of producing samples for in situ XAS and XMCD studies by magnetron sputtering are discussed.

  20. Colored and transparent oxide thin films prepared by magnetron sputtering: the glass blower approach.

    PubMed

    Gil-Rostra, Jorge; Chaboy, Jesús; Yubero, Francisco; Vilajoana, Antoni; González-Elipe, Agustín R

    2013-03-01

    This work describes the reactive magnetron sputtering processing at room temperature of several mixed oxide MxSiyOz thin films (M: Fe, Ni, Co, Mo, W, Cu) intended for optical, coloring, and aesthetic applications. Specific colors can be selected by adjusting the plasma gas composition and the Si-M ratio in the magnetron target. The microstructure and chemistry of the films are characterized by a large variety of techniques including X-ray photoemission spectroscopy, X-ray absorption spectroscopy (XAS), and infrared spectroscopy, while their optical properties are characterized by UV-vis transmission and reflection analysis. Particularly, XAS analysis of the M cations in the amorphous thin films has provided valuable information about their chemical state and local structure. It is concluded that the M cations are randomly distributed within the SiO2 matrix and that both the M concentration and its chemical state are the key parameters to control the final color of the films.

  1. Structural formation and photocatalytic activity of magnetron sputtered titania and doped-titania coatings.

    PubMed

    Kelly, Peter J; West, Glen T; Ratova, Marina; Fisher, Leanne; Ostovarpour, Soheyla; Verran, Joanna

    2014-10-13

    Titania and doped-titania coatings can be deposited by a wide range of techniques; this paper will concentrate on magnetron sputtering techniques, including "conventional" reactive co-sputtering from multiple metal targets and the recently introduced high power impulse magnetron sputtering (HiPIMS). The latter has been shown to deliver a relatively low thermal flux to the substrate, whilst still allowing the direct deposition of crystalline titania coatings and, therefore, offers the potential to deposit photocatalytically active titania coatings directly onto thermally sensitive substrates. The deposition of coatings via these techniques will be discussed, as will the characterisation of the coatings by XRD, SEM, EDX, optical spectroscopy, etc. The assessment of photocatalytic activity and photoactivity through the decomposition of an organic dye (methylene blue), the inactivation of E. coli microorganisms and the measurement of water contact angles will be described. The impact of different deposition technologies, doping and co-doping strategies on coating structure and activity will be also considered.

  2. [Spectrum diagnostics for optimization of experimental parameters in thin films deposited by magnetron sputtering].

    PubMed

    Guo, Qing-Lin; Cui, Yong-Liang; Chen, Jian-Hui; Zhang, Jin-Ping; Huai, Su-Fang; Liu, Bao-Ting; Chen, Jin-Zhong

    2010-12-01

    The plasma emission spectra generated during the deposition process of Si-based thin films by radio frequency (RF) magnetron sputtering using Cu and Al targets in an argon atmosphere were acquired by the plasma analysis system, which consists of a magnetron sputtering apparatus, an Omni-lambda300 series grating spectrometer, a CCD data acquisition system and an optical fiber transmission system. The variation in Cu and Al plasma emission spectra intensity depending on sputtering conditions, such as sputtering time, sputtering power, the target-to-substrate distance and deposition pressure, was studied by using the analysis lines Cu I 324. 754 nm, Cu I 327. 396 nm, Cu I 333. 784 nm, Cu I 353. 039 nm, Al I 394. 403 nm and Al I 396. 153 nm. Compared with the option of experimental parameters of thin films deposited by RF magnetron sputtering, it was shown that emission spectra analysis methods play a guiding role in optimizing the deposition conditions of thin films in RF magnetron sputtering.

  3. Magnetron sputtered nanostructured cadmium oxide films for ammonia sensing

    SciTech Connect

    Dhivya, P.; Prasad, A.K.; Sridharan, M.

    2014-06-01

    Nanostructured cadmium oxide (CdO) films were deposited on to glass substrates by reactive dc magnetron sputtering technique. The depositions were carried out for different deposition times in order to obtain films with varying thicknesses. The CdO films were polycrystalline in nature with cubic structure showing preferred orientation in (1 1 1) direction as observed by X-ray diffraction (XRD). Field-emission scanning electron microscope (FE-SEM) micrographs showed uniform distribution of grains of 30–35 nm size and change in morphology from spherical to elliptical structures upon increasing the film thickness. The optical band gap value of the CdO films decreased from 2.67 to 2.36 eV with increase in the thickness. CdO films were deposited on to interdigitated electrodes to be employed as ammonia (NH{sub 3}) gas sensor. The fabricated CdO sensor with thickness of 294 nm has a capacity to detect NH{sub 3} as low as 50 ppm at a relatively low operating temperature of 150 °C with quick response and recovery time. - Highlights: • Nanostructured CdO films were deposited on to glass substrates using magnetron sputtering. • Deposition time was varied in order to obtain films with different thicknesses. • The CdO films were polycrystalline in nature with preferred orientation along (1 1 1) direction. • The optical bandgap values of the films decreased on increasing the thickness of the films. • CdO films with different thickness such as 122, 204, 294 nm was capable to detect NH{sub 3} down to 50 ppm at operating temperature of 150 °C.

  4. Magnetron-Sputtered YSZ and CGO Electrolytes for SOFC

    NASA Astrophysics Data System (ADS)

    Solovyev, A. A.; Shipilova, A. V.; Ionov, I. V.; Kovalchuk, A. N.; Rabotkin, S. V.; Oskirko, V. O.

    2016-08-01

    Reactive magnetron sputtering has been used for deposition of yttria-stabilized ZrO2 (YSZ) and gadolinium-doped CeO2 (CGO) layers on NiO-YSZ commercial anodes for solid oxide fuel cells. To increase the deposition rate and improve the quality of the sputtered thin oxide films, asymmetric bipolar pulse magnetron sputtering was applied. Three types of anode-supported cells, with single-layer YSZ or CGO and YSZ/CGO bilayer electrolyte, were prepared and investigated. Optimal thickness of oxide layers was determined experimentally. Based on the electrochemical characteristics of the cells, it is shown that, at lower operating temperatures of 650°C to 700°C, the cells with single-layer CGO electrolyte are most effective. The power density of these fuel cells exceeds that of the cell based on YSZ single-layer electrolyte at the same temperature. Power densities of 650 mW cm-2 and 500 mW cm-2 at 700°C were demonstrated by cells with single-layer YSZ and CGO electrolyte, respectively. Significantly enhanced maximum power density was achieved in a bilayer-electrolyte single cell, as compared with cells with a single electrolyte layer. Maximum power density of 1.25 W cm-2 at 800°C and 1 W cm-2 at 750°C under voltage of 0.7 V were achieved for the YSZ/CGO bilayer electrolyte cell with YSZ and CGO thickness of about 4 μm and 1.5 μm, respectively. This signifies that the YSZ thin film serves as a blocking layer to prevent electrical current leakage in the CGO layer, leading to the overall enhanced performance. This performance is comparable to the state of the art for cells based on YSZ/CGO bilayer electrolyte.

  5. Generation of protein-reactive antibodies by short peptides is an event of high frequency: implications for the structural basis of immune recognition.

    PubMed Central

    Niman, H L; Houghten, R A; Walker, L E; Reisfeld, R A; Wilson, I A; Hogle, J M; Lerner, R A

    1983-01-01

    Recent studies have shown that chemically synthesized small peptides can induce antibodies that often react with intact proteins regardless of their position in the folded molecule. These findings are difficult to explain in view of the experimental and theoretical data which suggest that in the absence of forces provided by the folded protein, small peptides in aqueous solution do not readily adopt stable structures. In order to rationalize the two findings, there has been general acceptance of a stochastic model which suggests that the multiple conformers of a peptide in solution induce sets of antibodies with a small percentage reactive with conformations shared by the folded protein. This stochastic model has become less tenable as the success rate for the generation of protein-reactive anti-peptide antibodies has grown. To test the stochastic model, we have used monoclonal anti-peptide antibodies as a way of estimating the frequency with which small peptides induce antibodies that react with folded proteins. We have made monoclonal antibodies to six chemically synthesized peptides from three proteins. The frequency with which the peptides induce protein-reactive antibodies is at least 4 orders of magnitude greater than expected from previous experimental work and vastly different from what would be predicted by calculating the possible number of peptide conformers in solution. These findings make the stochastic model less likely and lead to consideration of other models. Aside from their practical significance for generation of highly specific reagents, these findings may have important implications for the protein folding problem. Images PMID:6192445

  6. Spatiotemporal synchronization of drift waves in a magnetron sputtering plasma

    SciTech Connect

    Martines, E.; Zuin, M.; Cavazzana, R.; Antoni, V.; Serianni, G.; Spolaore, M.; Vianello, N.; Adámek, J.

    2014-10-15

    A feedforward scheme is applied for drift waves control in a magnetized magnetron sputtering plasma. A system of driven electrodes collecting electron current in a limited region of the explored plasma is used to interact with unstable drift waves. Drift waves actually appear as electrostatic modes characterized by discrete wavelengths of the order of few centimeters and frequencies of about 100 kHz. The effect of external quasi-periodic, both in time and space, travelling perturbations is studied. Particular emphasis is given to the role played by the phase relation between the natural and the imposed fluctuations. It is observed that it is possible by means of localized electrodes, collecting currents which are negligible with respect to those flowing in the plasma, to transfer energy to one single mode and to reduce that associated to the others. Due to the weakness of the external action, only partial control has been achieved.

  7. Experimental investigation of quasiperiodic-chaotic-quasiperiodic-chaotic transition in a direct current magnetron sputtering plasma

    SciTech Connect

    Sabavath, Gopi Kishan; Banerjee, I.; Mahapatra, S. K.; Shaw, Pankaj Kumar; Sekar Iyengar, A. N.

    2015-08-15

    Floating potential fluctuations from a direct current magnetron sputtering plasma have been analysed using time series analysis techniques like phase space plots, power spectra, frequency bifurcation plot, etc. The system exhibits quasiperiodic-chaotic-quasiperiodic-chaotic transitions as the discharge voltage was increased. The transitions of the fluctuations, quantified using the largest Lyapunov exponent, have been corroborated by Hurst exponent and the Shannon entropy. The Shannon entropy is high for quasiperiodic and low for chaotic oscillations.

  8. Magnetron cathodes in plasma electrode Pockels cells

    DOEpatents

    Rhodes, M.A.

    1995-04-25

    Magnetron cathodes, which produce high current discharges, form greatly improved plasma electrodes on each side of an electro-optic crystal. The plasma electrode has a low pressure gas region on both sides of the crystal. When the gas is ionized, e.g., by a glow discharge in the low pressure gas, the plasma formed is a good conductor. The gas electrode acts as a highly uniform conducting electrode. Since the plasma is transparent to a high energy laser beam passing through the crystal, the plasma is transparent. A crystal exposed from two sides to such a plasma can be charged up uniformly to any desired voltage. A typical configuration utilizes helium at 50 millitorr operating pressure and 2 kA discharge current. The magnetron cathode produces a more uniform plasma and allows a reduced operating pressure which leads to lower plasma resistivity and a more uniform charge on the crystal. 5 figs.

  9. Magnetron cathodes in plasma electrode pockels cells

    DOEpatents

    Rhodes, Mark A.

    1995-01-01

    Magnetron cathodes, which produce high current discharges, form greatly improved plasma electrodes on each side of an electro-optic crystal. The plasma electrode has a low pressure gas region on both sides of the crystal. When the gas is ionized, e.g., by a glow discharge in the low pressure gas, the plasma formed is a good conductor. The gas electrode acts as a highly uniform conducting electrode. Since the plasma is transparent to a high energy laser beam passing through the crystal, the plasma is transparent. A crystal exposed from two sides to such a plasma can be charged up uniformly to any desired voltage. A typical configuration utilizes helium at 50 millitorr operating. pressure and 2 kA discharge current. The magnetron cathode produces a more uniform plasma and allows a reduced operating pressure which leads to lower plasma resistivity and a more uniform charge on the crystal.

  10. Metamaterial Cathodes in Multi-Cavity Magnetrons

    DTIC Science & Technology

    2011-06-01

    P.S. Campbell , R.R. Lentz, W.T. Main, S.G. Tantawi, K.G. Kato, H.K. Beutel, K.W. Brown, D.D. Crouch, G.K. Jones, and R.B. McDonald, “Develop- ment...14] G.A. Mesyats, Explosive Electron Emission, URO Press, 1998. [15] R.B. Miller, “The relativistic microwave magnetron,” in An Introduction to

  11. Particle contamination formation in magnetron sputtering processes

    SciTech Connect

    Selwyn, G.S.; Sequeda, F.; Huang, C.

    1997-07-01

    Defects caused by particulate contamination are an important concern in the fabrication of thin film products. Often, magnetron sputtering processes are used for this purpose. Particle contamination generated during thin film processing can be detected using laser light scattering, a powerful diagnostic technique which provides real-time, {ital in situ} imaging of particles {gt}0.3 {mu}m on the target, substrate, or in the plasma. Using this technique, we demonstrate that the mechanisms for particle generation, transport, and trapping during magnetron sputter deposition are different from the mechanisms reported in previously studied plasma etch processes, due to the inherent spatial nonuniformity of magnetically enhanced plasmas. During magnetron sputter deposition, one source of particle contamination is linked to portions of the sputtering target surface exposed to weaker plasma density. There, film redeposition induces filament or nodule growth. Sputter removal of these features is inhibited by the dependence of sputter yield on angle of incidence. These features enhance trapping of plasma particles, which then increases filament growth. Eventually the growths effectively {open_quotes}short-circuit{close_quotes} the sheath, causing high currents to flow through these features. This, in turn, causes mechanical failure of the growth resulting in fracture and ejection of the target contaminants into the plasma and onto the substrate. Evidence of this effect has been observed in semiconductor fabrication and storage disk manufacturing. Discovery of this mechanism in both technologies suggests it may be universal to many sputter processes. {copyright} {ital 1997 American Vacuum Society.}

  12. Fuzzy tungsten in a magnetron sputtering device

    NASA Astrophysics Data System (ADS)

    Petty, T. J.; Khan, A.; Heil, T.; Bradley, J. W.

    2016-11-01

    Helium ion induced tungsten nanostructure (tungsten fuzz) has been studied in a magnetron sputtering device. Three parameters were varied, the fluence from 3.4 × 1023-3.0 × 1024 m-2, the He ion energy from 25 to 70 eV, and the surface temperature from 900 to 1200 K. For each sample, SEM images were captured, and measurements of the fuzz layer thickness, surface roughness, reflectivity, and average structure widths are provided. A cross-over point from pre-fuzz to fully formed fuzz is found at 2.4 ± 0.4 × 1024 m-2, and a temperature of 1080 ± 60 K. No significant change was observed in the energy sweep. The fuzz is compared to low fluence fuzz created in the PISCES-A linear plasma device. Magnetron fuzz is less uniform than fuzz created by PISCES-A and with generally larger structure widths. The thicknesses of the magnetron samples follow the original Φ1/2 relation as opposed to the incubation fluence fit.

  13. Method and apparatus for improved high power impulse magnetron sputtering

    DOEpatents

    Anders, Andre

    2013-11-05

    A high power impulse magnetron sputtering apparatus and method using a vacuum chamber with a magnetron target and a substrate positioned in the vacuum chamber. A field coil being positioned between the magnetron target and substrate, and a pulsed power supply and/or a coil bias power supply connected to the field coil. The pulsed power supply connected to the field coil, and the pulsed power supply outputting power pulse widths of greater that 100 .mu.s.

  14. Satellite Power System (SPS) magnetron tube assessment study

    NASA Technical Reports Server (NTRS)

    Brown, W. C.

    1981-01-01

    The data base was extended with respect to the magnetron directional amplifier and its operating parameters that are pertinent to its application in the solar power satellite. On the basis of the resulting extended data base the design of a magnetron was outlined that would meet the requirements of the SPS application and a technology program was designed that would result in its development. The proposed magnetron design for the SPS is a close scale of the microwave oven magnetron, and resembles it closely physically and electrically.

  15. Drastic improvement in the S-band relativistic magnetron operation

    NASA Astrophysics Data System (ADS)

    Sayapin, A.; Hadas, Y.; Krasik, Ya. E.

    2009-08-01

    The superior operation of a S-band relativistic magnetron powered by a Linear Induction Accelerator with ≤400 kV, ≤4 kA, and ˜150 ns output pulses was revealed when the magnetron was coupled with a resonance load and a part of the generated microwave power stored in the resonator was reflected back to the magnetron. It is shown that, under optimal conditions, the efficiency of the magnetron operation increases by ˜40% and the generated microwave power reaches the power of the electron beam.

  16. Effect of buffer layer on thermochromic performances of VO2 films fabricated by magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Zhu, Benqin; Tao, Haizheng; Zhao, Xiujian

    2016-03-01

    As a well-developed industrial fabricating method, magnetron sputtering technique has its distinct advantages for the large-scale production. In order to investigate the effect of buffer layer on the formation and thermochromic performances of VO2 films, using RF magnetron sputtering method, we fabricated three kinds of buffer layers SiO2, TiO2 and SnO2 on soda lime float-glass. Then according to the reactive DC magnetron sputtering method, VO2 films were deposited. Due to the restriction of heat treatment temperature when using soda lime float-glass as substrates, dense rutile phase TiO2 cannot be formed, leading to the formation of vanadium oxide compounds containing Na ions. When using SnO2 as buffer layer, we found that relatively high pure VO2 can be deposited more easily. In addition, compared with the effect of SiO2 buffer layer, we observed an enhanced visible transparency, a decreased infrared emissivity, which should be mainly originated from the modified morphology and/or the hetero-structured VO2/SnO2 interface.

  17. A modified relativistic magnetron with TEM output mode

    NASA Astrophysics Data System (ADS)

    Shi, Di-Fu; Qian, Bao-Liang; Wang, Hong-Gang; Li, Wei; Ju, Jin-Chuan; Du, Guang-Xing

    2017-01-01

    A modified relativistic magnetron (RM) with TEM output mode is proposed. By setting the coupling slots at the bottom of the resonant cavities in the transmission region rather than in the interaction region, besides possessing the original RM's advantages of high power conversion efficiency and radiating the lowest order mode, the modified RM not only improves the compactness and miniaturization of the magnetic field system, which is beneficial to realize the RMs packed by a permanent magnet, but also improves the robustness of operating frequency to structural perturbations of the coupling slots, which contributes to optimize the RM performance by adjusting the coupling slot dimensions with a relatively stable operating frequency. In the three-dimensional particle-in-cell (PIC) simulation, the modified RM with a reduction of 27.2% in the weight of the coils, 35.8% in the occupied space of the coils, and 18.6% in the operating current, can output a relatively pure TEM mode, which has been demonstrated as the dominant output mode by simulation, corresponding to an output power of 495.0 MW and a power conversion efficiency of 56.4%, at the resonant frequency of 4.30 GHz. In addition, an output power of above 2 GW can also be obtained from the RM in simulations.

  18. Ground state atomic oxygen in high-power impulse magnetron sputtering: a quantitative study

    NASA Astrophysics Data System (ADS)

    Britun, Nikolay; Belosludtsev, Alexandr; Silva, Tiago; Snyders, Rony

    2017-02-01

    The ground state density of oxygen atoms in reactive high-power impulse magnetron sputtering discharges has been studied quantitatively. Both time-resolved and space-resolved measurements were conducted. The measurements were performed using two-photon absorption laser-induced fluorescence (TALIF), and calibrated by optical emission actinometry with multiple Ar emission lines. The results clarify the dynamics of the O ground state atoms in the discharge afterglow significantly, including their propagation and fast decay after the plasma pulse, as well as the influence of gas pressure, O2 admixture, etc.

  19. Plasma"anti-assistance" and"self-assistance" to high power impulse magnetron sputtering

    SciTech Connect

    Anders, Andre; Yushkov, Georgy Yu.

    2009-01-30

    A plasma assistance system was investigated with the goal to operate high power impulse magnetron sputtering (HiPIMS) at lower pressure than usual, thereby to enhance the utilization of the ballistic atoms and ions with high kinetic energy in the film growth process. Gas plasma flow from a constricted plasma source was aimed at the magnetron target. Contrary to initial expectations, such plasma assistance turned out to be contra-productive because it led to the extinction of the magnetron discharge. The effect can be explained by gas rarefaction. A better method of reducing the necessary gas pressure is operation at relatively high pulse repetition rates where the afterglow plasma of one pulse assists in the development of the next pulse. Here we show that this method, known from medium-frequency (MF) pulsed sputtering, is also very important at the much lower pulse repetition rates of HiPIMS. A minimum in the possible operational pressure is found in the frequency region between HiPIMS and MF pulsed sputtering.

  20. Development of a 14-vane, double-strapped, 5.8-GHz magnetron oscillator

    NASA Astrophysics Data System (ADS)

    Choi, Jin Joo; Lee, Han Seoul; Jang, Kwang Ho; Sim, Sung Hun; Choi, Heung Sik

    2016-08-01

    Experiments on a 14-vane, double-strapped magnetron oscillator were performed to demonstrate high-power, high-efficiency coherent radiation at 5.8 GHz. The double-strapped magnetron was designed by using the Buneman-Hatree resonance condition, electromagnetic simulations and non-linear three-dimensional particle-in-cell (PIC) simulations. Experiments showed an oscillation output power of 5.3 kW at 5.79 GHz, corresponding to a DC-RF conversion efficiency of 57%. The cathode voltage was 9.2 kV, the collected anode current was 1 A, and the external magnetic field is 7.5 kG. Experimental results for the RF power, oscillation frequency, and efficiency were in good agreement with the corresponding values from non-linear three-dimensional PIC simulations.

  1. A novel relativistic magnetron with circularly polarized TE11 coaxial waveguide mode

    NASA Astrophysics Data System (ADS)

    Shi, Di-Fu; Qian, Bao-Liang; Wang, Hong-Gang; Li, Wei; Du, Guang-Xing

    2016-11-01

    A novel relativistic magnetron (RM) with a circularly polarized TE11 coaxial waveguide mode and its corresponding mode excitation are investigated in this paper. By operating in the 4π/5 mode in the ten-cavity RM and compactly designing the RM structure with the all cavity-magnetron axial extraction technique, the RM can directly output a circularly polarized TE11 coaxial waveguide mode in a reversible direction of rotation without any mode converters. In addition, the analysis of mode excitation can be generalized to a 2N-cavity RM, where 2N  >  4 is the number of cavities. Results of the 3D particle-in-cell (PIC) simulation show that a high power microwave (HPM) with an operating frequency of 4.15 GHz and an output power of 700 MW is obtained from the RM, corresponding to the power conversion efficiency of 50.0%.

  2. Optical Properties of Magnetron sputtered Nickel Thin Films

    NASA Astrophysics Data System (ADS)

    Twagirayezu, Fidele; Geerts, Wilhelmus J.; Cui, Yubo

    2015-03-01

    The study of optical properties of Nickel (Ni) is important, given the pivotal role it plays in the semiconductor and nano-electronics technology. Ni films were made by DC and RF magnetron sputtering in an ATC Orion sputtering system of AJA on various substrates. The optical properties were studied ex situ by variable angle spectroscopic (220-1000 nm) ellipsometry at room temperature. The data were modeled and analyzed using the Woollam CompleteEase Software fitting ellipsometric and transmission data. Films sputtered at low pressure have optical properties similar to that of Palik. Films sputtered at higher pressure however have a lower refraction index and extinction coefficient. It is expected from our results that the density of the sputtered films can be determined from the ellipsometric quantities. Our experiments also revealed that Ni is susceptible to a slow oxidation changing its optical properties over the course of several weeks. The optical properties of the native oxide differ from those of reactive sputtered NiO similar as found by. Furthermore the oxidation process of our samples is characterized by at least two different time constants.

  3. The effect of magnetron pulsing on the structure and properties of tribological Cr-Al-N coatings.

    PubMed

    Lin, Jianliang; Moore, John J; Mishra, Brajendra; Sproul, Williams D; Rees, John A

    2010-02-01

    The paper will discuss the effect of pulsing single or two unbalanced magnetrons in a closed magnetic field configuration on the structure and properties of tribological Cr-Al-N coatings. Nanocrystalline Cr-Al-N coatings were reactively deposited from Cr and Al elemental targets using two unbalanced magnetrons, which were powered in both dc, pulsing only Al target and asynchronously pulsing both Cr and Al targets at 100 kHz and 50% duty cycle conditions. The ion energy distributions of these deposition and pulsing conditions were characterized using a Hiden Electrostatic QuadruPole Plasma Analyzer. It was found that pulsing two magnetrons asynchronously at 100 kHz and 50% duty cycle produced higher ion energies and significant increased ion fluxes than pulsing none or pulsing only one (Al) target. The structure and properties of Cr-Al-N coatings synthesized under different dc and pulsing conditions were investigated using X-ray diffraction, scanning electron microscopy, nanoindentation and ball-on-disk wear test, and were correlated with the effects of ion energies and ion flux regimes observed in the plasma diagnostics. The advantages of using pulsed magnetron sputtering producing different energetic ion regimes to enhance the ion bombardment on the growing films and therefore achieving the improved density, refinement of grain size and properties are illustrated.

  4. Increased frequency of {gamma}{delta} T cells in cerebrospinal fluid and peripheral blood of patients with multiple sclerosis: Reactivity, cytotoxicity, and T cell receptor V gene rearrangements

    SciTech Connect

    Stinissen, P.; Vandevyver, C.; Medaer, R.

    1995-05-01

    Infiltrating {gamma}{delta} T cells are potentially involved in the central nervous system demyelination in multiple sclerosis (MS). To further study this hypothesis, we analyzed the frequency and functional properties of {gamma}{delta} T cells in peripheral blood (PB) and paired cerebrospinal fluid (CSF) of patients with MS and control subjects, including patients with other neurologic diseases (OND) and healthy individuals. The frequency analysis was performed under limiting dilution condition using rIL-2 and PHA. After PHA stimulation, a significantly increased frequency of {gamma}{delta} T cells was observed in PB and in CSF of MS patients as compared with PB and CSF of patients with OND. The frequency was represented equally in OND patients and normal individuals. Similarly, the IL-2-responsive {gamma}{delta} T cells occurred at a higher frequency in PB of MS than of control subjects. Forty-three percent of the {gamma}{delta} T cell clones isolates from PB and CSF of MS patients responded to heat shock protein (HSP70) but not HSP65, whereas only 2 of 30 control {gamma}{delta} T cell clones reacted to the HSP. The majority of the {gamma}{delta} T cell clones were able to induce non-MHC-restricted cytolysis of Daudi cells. All clones displayed a substantial reactivity to bacterial superantigens staphylococcal enterotoxin B and toxic shock syndrome toxin-1, irrespective of their {gamma}{delta} V gene usage. Furthermore, the {gamma}{delta} T cell clones expressed predominantly TCRDV2 and GV2 genes, whereas the clones derived from CSF of MS patients expressed either DV1 or DV2 genes. The obtained {gamma}{delta} clones, in general, represented rather heterogeneous clonal origins, even though a predominant clonal origin was found in a set of 10 {gamma}{delta} clones derived from one patient with MS. The present study provides new evidence supporting a possible role of {gamma}{delta} T cells in the secondary inflammatory processes in MS. 39 refs., 5 figs., 4 tabs.

  5. Evaporation-assisted high-power impulse magnetron sputtering: The deposition of tungsten oxide as a case study

    SciTech Connect

    Hemberg, Axel; Dauchot, Jean-Pierre; Snyders, Rony; Konstantinidis, Stephanos

    2012-07-15

    The deposition rate during the synthesis of tungsten trioxide thin films by reactive high-power impulse magnetron sputtering (HiPIMS) of a tungsten target increases, above the dc threshold, as a result of the appropriate combination of the target voltage, the pulse duration, and the amount of oxygen in the reactive atmosphere. This behavior is likely to be caused by the evaporation of the low melting point tungsten trioxide layer covering the metallic target in such working conditions. The HiPIMS process is therefore assisted by thermal evaporation of the target material.

  6. Ionized magnetron sputtering of aluminum(,2)oxygen(,3)

    NASA Astrophysics Data System (ADS)

    Gonzalez, Patrick Fernando

    2000-10-01

    This dissertation shows a detailed study of the conditions necessary for sputtering alumina using a novel variant of ionized magnetron sputtering (IMS) first demonstrated by Yamashita et. al. The study presented herein leverages concurrent research at our laboratory on high density plasmas, plasma characterization and charged particle beams research to demonstrate a new source capable of sputtering hydrated alumina films at high rates. High quality ceramics such as Al2O3 find uses in a variety of applications, and in particular, for mass storage applications. Consequently, there exists an ever-growing need to provide and improve the capability of growing thick insulating films. Ideally, the insulating film should be stoichiometric and able to be grown at rates high enough to be easily manufacturable. Alumina is a particularly attractive due to its high density, Na barrier properties, and stability and radiation resistance. However, high quality films are often difficult to achieve with conventional RF plasma due to extremely slow deposition rates and difficulties associated with system cooling. The preferred method is to reactively sputter Al from a solid target in an O2 ambient. Nevertheless, this process is inherently unstable and leads to arcing and uneven target wear when magnetrons are used. In this study, we build the sputtering source, evaluate, and maximize the deposition characteristics of alumina films sputtered from a solid target in an Ar/O2 ambient. Semi-crystalline (kappa + theta) alumina has been reported using a similar technique at temperatures as low 370 C. The difference in the system used herein is that RF power is used for both, the inductive and capacitive components. Additionally, we use a solid target made of sintered alumina throughout the experiment. A model is developed using regression analysis and compared to results obtained. Because plasma parameters can interact with each other, we explore ICP/CCP power interactions and gas influence

  7. Deposition Rates of High Power Impulse Magnetron Sputtering: Physics and Economics

    SciTech Connect

    Anders, Andre

    2009-11-22

    Deposition by high power impulse magnetron sputtering (HIPIMS) is considered by some as the new paradigm of advanced sputtering technology, yet this is met with skepticism by others for the reported lower deposition rates, if compared to rates of more conventional sputtering of equal average power. In this contribution, the underlying physical reasons for the rate changes are discussed, including (i) ion return to the target and self-sputtering, (ii) the less-than-linear increase of the sputtering yield with increasing ion energy, (iii) yield changes due to the shift of species responsible for sputtering, (iv) changes to due to greater film density, limited sticking, and self-sputtering on the substrate, (v) noticeable power losses in the switch module, (vi) changes of the magnetic balance and particle confinement of the magnetron due to self-fields at high current, and (vii) superposition of sputtering and sublimation/evaporation for selected materials. The situation is even more complicated for reactive systems where the target surface chemistry is a function of the reactive gas partial pressure and discharge conditions. While most of these factors imply a reduction of the normalized deposition rate, increased rates have been reported for certain conditions using hot targets and less poisoned targets. Finally, some points of economics and HIPIMS benefits considered.

  8. Electrostatic quadrupole plasma mass spectrometer measurements during thin film depositions using simultaneous matrix assisted pulsed laser evaporation and magnetron sputtering

    SciTech Connect

    Hunter, C. N.; Check, M. H.; Muratore, C.; Voevodin, A. A.

    2010-05-15

    A hybrid plasma deposition process, combining matrix assisted pulsed laser evaporation (MAPLE) of carbon nanopearls (CNPs) with magnetron sputtering of gold was investigated for growth of composite films, where 100 nm sized CNPs were encapsulated into a gold matrix. Composition and morphology of such composite films was characterized with x-ray photoelectron spectroscopy, scanning electron microscopy, and transmission electron microscopy (TEM) analysis. Carbon deposits on a gold magnetron sputter target and carbon impurities in the gold matrices of deposited films were observed while codepositing from gold and frozen toluene-CNP MAPLE targets in pure argon. Electrostatic quadrupole plasma analysis was used to determine that a likely mechanism for generation of carbon impurities was a reaction between toluene vapor generated from the MAPLE target and the argon plasma originating from the magnetron sputtering process. Carbon impurities of codeposited films were significantly reduced by introducing argon-oxygen mixtures into the deposition chamber; reactive oxygen species such as O and O+ effectively removed carbon contamination of gold matrix during the codeposition processes. Increasing the oxygen to argon ratio decreased the magnetron target sputter rate, and hence hybrid process optimization to prevent gold matrix contamination and maintain a high sputter yield is needed. High resolution TEM with energy dispersive spectrometry elemental mapping was used to study carbon distribution throughout the gold matrix as well as embedded CNP clusters. This research has demonstrated that a hybrid MAPLE and magnetron sputtering codeposition process is a viable means for synthesis of composite thin films from premanufactured nanoscale constituents, and that cross-process contaminations can be overcome with understanding of hybrid plasma process interaction mechanisms.

  9. Effect of space charge on the negative oxygen flux during reactive sputtering

    NASA Astrophysics Data System (ADS)

    Moens, F.; Kalvas, T.; Van Steenberge, S.; Depla, D.

    2017-03-01

    Negative ions often play a distinctive role in the phase formation during reactive sputter deposition. The path of these high energetic ions is often assumed to be straight. In this paper, it is shown that in the context of reactive magnetron sputtering space charge effects are decisive for the energetic negative ion trajectories. To investigate the effect of space charge spreading, reactive magnetron sputter experiments were performed in compound mode with target materials that are expected to have a high secondary ion emission yield (MgO and CeO2). By the combination of energy flux measurements, and simulations, a quantitative value for the negative oxygen ion yield can be derived.

  10. Ordering of Fine Particles in a Planar Magnetron Plasma

    SciTech Connect

    Hayashi, Y.; Takahashi, K.; Totsuji, H.; Ishihara, O.; Sato, N.; Watanabe, Y.; Adachi, S.

    2008-09-07

    Fine particles injected in a planar magnetron were pushed upward by diffusible plasma, leading to being suspended by the force balance with the gravity and forming three-dimensional structures on the two-dimensional structure formed by particle strings.

  11. On the evolution of film roughness during magnetron sputtering deposition

    SciTech Connect

    Turkin, A. A.; Pei, Y. T.; Shaha, K. P.; Chen, C. Q.; Vainshtein, D. I.; De Hosson, J. Th. M.

    2010-11-15

    The effect of long-range screening on the surface morphology of thin films grown with pulsed-dc (p-dc) magnetron sputtering is studied. The surface evolution is described by a stochastic diffusion equation that includes the nonlocal shadowing effects in three spatial dimensions. The diffusional relaxation and the angular distribution of the incident particle flux strongly influence the transition to the shadowing growth regime. In the magnetron sputtering deposition the shadowing effect is essential because of the configuration of the magnetron system (finite size of sputtered targets, rotating sample holder, etc.). A realistic angular distribution of depositing particles is constructed by taking into account the cylindrical magnetron geometry. Simulation results are compared with the experimental data of surface roughness evolution during 100 and 350 kHz p-dc deposition, respectively.

  12. Satellite power system (SPS) magnetron tube assessment study

    NASA Technical Reports Server (NTRS)

    1980-01-01

    Taks performed to extend the data base and to define a technology development program for the magnetron directional amplifier for the SPS are reviewed. These include: (1) demonstrating the tracking of phase and amplitude of the microwave output to phase and amplitude references; (2) expanding the range of power over which the directional amplifier will operate; (3)recognizing the importance of amplitude control in overall system design and in simplifying power conditioning; (4) developing a preliminary design for the overall architecture of the power module; (5) demonstrating magnetron starting using the amplitude control system; (6) mathematically modelling and performing a computerized study of the pyrolytic graphite radiating fin; (7) defining the mass of the magnetic circuit for the SPS tube; (8) noise measurement; (9) achieving harmonic suppression by notch reflection filters; (10) estimating the mass of the transmitting antenna; (11) developing a magnetron package with power generation, phase control, and power condition functions; and (12) projecting magnetron package characteristics.

  13. Performance and test results of a regulated magnetron pulser

    SciTech Connect

    Rose, C.R.; Warren, D.S.

    1998-12-31

    This paper describes the test results and performance of a 5.0-kV, 750-mA, regulated current pulser used to drive an Hitachi model 2M130 2,425-MHz magnetron. The magnetron is used to modulate the plasma in a particle accelerator injector. In this application, precise and stable rf power is crucial to extract a stable and accurate particle beam. A 10-kV high-voltage triode vacuum tube with active feedback is used to control the magnetron current and output rf power. The pulse width may be varied from as little as ten microseconds to continuous duty by varying the width of a supplied gate pulse. The output current level can be programmed between 10 and 750 mA. Current regulation and accuracy are better than 1%. The paper discusses the overall performance of the pulser and magnetron including anode current and rf power waveforms, linearity compliance, and vacuum tube performance.

  14. Friction characteristics of r. f. magnetron sputtered C and C:N thin films.

    NASA Astrophysics Data System (ADS)

    Sobota, Jaroslav

    Carbon and C:N layers were prepared using the commercially available Leybold-Heraeus Z 550 radio frequency magnetron sputtering plant. A graphite target of high purity (99.999 % C) was used. The tribological testing was performed with a reciprocating ball-on-disc tribometer. The sliding distance on the coating was defined as the time at which a scoring occurs, and the friction coefficient exhibits an abrupt increase. From this, and from the known amplitude of the reciprocating ball, the sliding distance was evaluated.

  15. Evidence for breathing modes in direct current, pulsed, and high power impulse magnetron sputtering plasmas

    SciTech Connect

    Yang, Yuchen; Zhou, Xue; Liu, Jason X.; Anders, André

    2016-01-18

    We present evidence for breathing modes in magnetron sputtering plasmas: periodic axial variations of plasma parameters with characteristic frequencies between 10 and 100 kHz. A set of azimuthally distributed probes shows synchronous oscillations of the floating potential. They appear most clearly when considering the intermediate current regime in which the direction of azimuthal spoke motion changes. Breathing oscillations were found to be superimposed on azimuthal spoke motion. Depending on pressure and current, one can also find a regime of chaotic fluctuations and one of stable discharges, the latter at high current. A pressure-current phase diagram for the different situations is proposed.

  16. Valproic acid increases conservative homologous recombination frequency and reactive oxygen species formation: a potential mechanism for valproic acid-induced neural tube defects.

    PubMed

    Defoort, Ericka N; Kim, Perry M; Winn, Louise M

    2006-04-01

    Valproic acid, a commonly used antiepileptic agent, is associated with a 1 to 2% incidence of neural tube defects when taken during pregnancy; however, the molecular mechanism by which this occurs has not been elucidated. Previous research suggests that valproic acid exposure leads to an increase in reactive oxygen species (ROS). DNA damage due to ROS can result in DNA double-strand breaks, which can be repaired through homologous recombination (HR), a process that is not error-free and can result in detrimental genetic changes. Because the developing embryo requires tight regulation of gene expression to develop properly, we propose that the loss or dysfunction of genes involved in embryonic development through aberrant HR may ultimately cause neural tube defects. To determine whether valproic acid induces HR, Chinese hamster ovary 3-6 cells, containing a neomycin direct repeat recombination substrate, were exposed to valproic acid for 4 or 24 h. A significant increase in HR after exposure to valproic acid (5 and 10 mM) for 24 h was observed, which seems to occur through a conservative HR mechanism. We also demonstrated that exposure to valproic acid (5 and 10 mM) significantly increased intracellular ROS levels, which were attenuated by preincubation with polyethylene glycol-conjugated (PEG)-catalase. A significant change in the ratio of 8-hydroxy-2'-deoxyguanosine/2'-de-oxyguanosine, a measure of DNA oxidation, was not observed after valproic acid exposure; however, preincubation with PEG-catalase significantly blocked the increase in HR. These data demonstrate that valproic acid increases HR frequency and provides a possible mechanism for valproic acid-induced neural tube defects.

  17. Composition-dependent structure of polycrystalline magnetron-sputtered V-Al-C-N hard coatings studied by XRD, XPS, XANES and EXAFS.

    PubMed

    Krause, Bärbel; Darma, Susan; Kaufholz, Marthe; Mangold, Stefan; Doyle, Stephen; Ulrich, Sven; Leiste, Harald; Stüber, Michael; Baumbach, Tilo

    2013-08-01

    V-Al-C-N hard coatings with high carbon content were deposited by reactive radio-frequency magnetron sputtering using an experimental combinatorial approach, deposition from a segmented sputter target. The composition-dependent coexisting phases within the coating were analysed using the complementary methods of X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), X-ray absorption near-edge spectroscopy (XANES) and extended X-ray absorption fine-structure spectroscopy (EXAFS). For the analysis of the X-ray absorption near-edge spectra, a new approach for evaluation of the pre-edge peak was developed, taking into account the self-absorption effects in thin films. Within the studied composition range, a mixed face-centred cubic (V,Al)(C,N) phase coexisting with a C-C-containing phase was observed. No indication of hexagonal (V,Al)(N,C) was found. The example of V-Al-C-N demonstrates how important a combination of complementary methods is for the detection of coexisting phases in complex multi-element coatings.

  18. Composition-dependent structure of polycrystalline magnetron-sputtered V–Al–C–N hard coatings studied by XRD, XPS, XANES and EXAFS

    PubMed Central

    Krause, Bärbel; Darma, Susan; Kaufholz, Marthe; Mangold, Stefan; Doyle, Stephen; Ulrich, Sven; Leiste, Harald; Stüber, Michael; Baumbach, Tilo

    2013-01-01

    V–Al–C–N hard coatings with high carbon content were deposited by reactive radio-frequency magnetron sputtering using an experimental combinatorial approach, deposition from a segmented sputter target. The composition-dependent coexisting phases within the coating were analysed using the complementary methods of X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), X-ray absorption near-edge spectroscopy (XANES) and extended X-ray absorption fine-structure spectroscopy (EXAFS). For the analysis of the X-ray absorption near-edge spectra, a new approach for evaluation of the pre-edge peak was developed, taking into account the self-absorption effects in thin films. Within the studied composition range, a mixed face-centred cubic (V,Al)(C,N) phase coexisting with a C–C-containing phase was observed. No indication of hexagonal (V,Al)(N,C) was found. The example of V–Al–C–N demonstrates how important a combination of complementary methods is for the detection of coexisting phases in complex multi-element coatings. PMID:24046506

  19. Thick beryllium coatings by magnetron sputtering

    SciTech Connect

    Wu, H; Nikroo, A; Youngblood, K; Moreno, K; Wu, D; Fuller, T; Alford, C; Hayes, J; Detor, A; Wong, M; Hamza, A; van Buuren, T; Chason, E

    2011-04-14

    Thick (>150 {micro}m) beryllium coatings are studied as an ablator material of interest for fusion fuel capsules for the National Ignition Facility (NIF). As an added complication, the coatings are deposited on mm-scale spherical substrates, as opposed to flats. DC magnetron sputtering is used because of the relative controllability of the processing temperature and energy of the deposits. We used ultra small angle x-ray spectroscopy (USAXS) to characterize the void fraction and distribution along the spherical surface. We investigated the void structure using a combination focused ion beam (FIB) and scanning electron microscope (SEM), along with transmission electron microscopy (TEM). Our results show a few volume percent of voids and a typical void diameter of less than two hundred nanometers. Understanding how the stresses in the deposited material develop with thickness is important so that we can minimize film cracking and delamination. To that end, an in-situ multiple optical beam stress sensor (MOSS) was used to measure the stress behavior of thick Beryllium coatings on flat substrates as the material was being deposited. We will show how the film stress saturates with thickness and changes with pressure.

  20. Model for designing planar magnetron cathodes

    SciTech Connect

    Garcia, M.

    1997-05-30

    Planar magnetron cathodes have arching magnetic field lines which concentrate plasma density to enhance ion bombardment and sputtering. Typical parameters are: helium at 1 to 300 milli-torr, 200 to 2000 gauss at the cathode, 200 to 800 volts, and plasma density decreasing by up to ten times within 2 to 10 cm from the cathode. A 2D, quasineutral, fluid model yields formulas for the plasma density: n(x,y), current densities: j(x,y), j{sub e}(x,y), j{sub +}(x,y), the electric field: E{sub y}(y), and the voltage between the cathode surface and a distant plasma. An ion sheath develops between the cathode and the quasineutral flow. The thickness of this sheath depends on processes in the quasineutral flow. Experiments shows that T{sub e} (3 {yields} 8 eV) adjusts to ensure that {alpha}{sub 0}{tau} {approx} 2.5 in helium, for ionization rate {alpha}{sub 0} (10{sup 4} {yields} 10{sup 5} s{sup -1}), and electron transit time to the unmagnetized plasma {tau} (10 {yields} 100 {micro}s). Helium glow discharge cathode fall {alpha}{sub 0}{tau} is about 2.5, though this occurs at much higher voltage.

  1. Codeposition of amorphous zinc tin oxide using high power impulse magnetron sputtering: characterisation and doping

    NASA Astrophysics Data System (ADS)

    Tran, H. N.; Mayes, E. L. H.; Murdoch, B. J.; McCulloch, D. G.; McKenzie, D. R.; Bilek, M. M. M.; Holland, A. S.; Partridge, J. G.

    2017-04-01

    Thin film zinc tin oxide (ZTO) has been energetically deposited at 100 °C using high power impulse magnetron sputtering (HiPIMS). Reactive co-deposition from Zn (HiPIMS mode) and Sn (DC magnetron sputtering mode) targets yielded a gradient in the Zn:Sn ratio across a 4-inch diameter sapphire substrate. The electrical and optical properties of the film were studied as a function of composition. As-deposited, the films were amorphous, transparent and semi-insulating. Hydrogen was introduced by post-deposition annealing (1 h, 500 °C, 100 mTorr H2) and resulted in significantly increased conductivity with no measurable structural alterations. After annealing, Hall effect measurements revealed n-type carrier concentrations of ∼1 × 1017 cm‑3 and mobilities of up to 13 cm2 V‑1 s–1. These characteristics are suitable for device applications and proved stable. X-ray photoelectron spectroscopy was used to explore the valence band structure and to show that downward surface band-bending resulted from OH attachment. The results suggest that HiPIMS can produce dense, high quality amorphous ZTO suitable for applications including transparent thin film transistors.

  2. Continuous and nanostructured TiO2 films grown by dc sputtering magnetron.

    PubMed

    Sánchez, O; Vergara, L; Font, A Climent; de Melo, O; Sanz, R; Hernández-Vélez, M

    2012-12-01

    The growth of Anatase nanostructured films using dc reactive magnetron sputtering and post-annealing treatment is reported. TiO2 has been deposited on Porous Anodic Alumina Films used as templates which were previously grown in phosphoric acid solution and etched to modify their pore diameters. This synthesis via results in the formation of vertically aligned and spatially ordered TiO2 nanostructures replicating the underlying template. Previously, the growth optimization of TiO2 thin films deposited by dc magnetron sputtering on flat silicon substrates was done. The crystalline structure and Ti in-depth concentration profile were determined by grazing incidence X-ray diffraction and Rutherford backscattering spectrometry, respectively. The surface morphology of the samples was explored by mean of a Field Emission Gun scanning electron microscope. Optical properties of the nanostructured samples were studied by using the reflectance spectra received in the UV-visible range. In these spectra different band gap values and complex light absorption features were observed.

  3. Characteristics of end Hall ion source with magnetron hollow cathode discharge

    NASA Astrophysics Data System (ADS)

    Tang, Deli; Wang, Lisheng; Pu, Shihao; Cheng, Changming; Chu, Paul K.

    2007-04-01

    An end Hall ion source with magnetron hollow cathode discharge is described. The source is suitable for high current, low energy ion beam applications such as Hall current plasma accelerators. The end Hall ion source is based on an anode layer thruster with closed drift electrons that move in a closed path in the E × B field. Only a simple magnetron power supply is used in the ion source. The special configuration enables uninterrupted and expanded operation with oxygen as well as other reactive gases because of the absence of an electron source in the ion source. In our evaluation, the ion beam current was measured by a circular electrostatic probe and the energy distribution of the ion beam was measured by a retarding potential analyzer (RPA). An ion beam current density of up to 10 mA/cm2 was obtained at a mean ion energy of 100-250 eV using Ar or O2. The ion source can be operated in a stable fashion at a discharge voltage between 200 and 500 V and without additional electron triggering. The discharge power of the ion source can be easily changed by adjusting the gas flow rate and anode voltage. No water cooling is needed for power from 500 W to 2 kW. The simple and rugged ion source is suitable for industrial applications such as deposition of thin films with enhanced adhesion. The operational characteristics of the ion source are experimentally determined and discussed.

  4. The role of pulse length in target poisoning during reactive HiPIMS: application to amorphous HfO2

    NASA Astrophysics Data System (ADS)

    Ganesan, R.; Murdoch, B. J.; Treverrow, B.; Ross, A. E.; Falconer, I. S.; Kondyurin, A.; McCulloch, D. G.; Partridge, J. G.; McKenzie, D. R.; Bilek, M. M. M.

    2015-06-01

    In conventional reactive magnetron sputtering, target poisoning frequently leads to an instability that requires the reactive gas flow rate to be actively regulated to maintain a constant composition of the deposited layers. Here we demonstrate that the pulse length in high power impulse magnetron sputtering (HiPIMS) is important for determining the surface conditions on the target that lead to poisoning. By increasing the pulse length, a smooth transition can be achieved from a poisoned target condition (short pulses) to a quasi-metallic target condition (long pulses). Appropriate selection of pulse length eliminates the need for active regulation, enabling stable reactive magnetron sputter deposition of stoichiometric amorphous hafnium oxide (HfO2) from a Hf target. A model is presented for the reactive HiPIMS process in which the target operates in a partially poisoned mode with a distribution of oxide on its surface that depends on the pulse length.

  5. Evolution of film temperature during magnetron sputtering

    SciTech Connect

    Shaginyan, L.R.; Han, J.G.; Shaginyan, V.R.; Musil, J.

    2006-07-15

    We report on the results of measurements of the temperature T{sup F}{sub surf} which developed on the surface of films deposited by magnetron sputtering of chromium and copper targets on cooling and non-cooling silicon substrates. The T{sup F}{sub surf} and substrate temperature (T{sub s}) were simultaneously measured using high-resolution IR camera and thermocouple, respectively. We revealed that the T{sup F}{sub surf} steeply grows, keeps constant when it achieves saturation level, and rapidly drops to the value of the T{sub s} after stopping the deposition. At the same time, the T{sub s} either does not change for the case of cooling substrate or increases to a certain level for noncooling substrate. However, in both cases the T{sub s} remains several times lower than the T{sup F}{sub surf}. The T{sup F}{sub surf} is proportional to the flux of energy delivered to the growth surface by sputtered atoms and other fast particles, weakly depends on the depositing metal and can achieve several hundreds of deg. C. This phenomenon is explained by a model assuming formation of a hot thin surface layer (HTSL) on the top of the growing film, which exists only during film deposition and exhibits extremely low thermal conductivity. Due to this unique property the temperature T{sup F}{sub surf} of HTSL is several times higher than the T{sub s}. Variations in the T{sup F}{sub surf} fairly correlate with structure changes of Cr films along thickness investigated in detail previously.

  6. Direct current magnetron sputtering deposition of InN thin films

    NASA Astrophysics Data System (ADS)

    Cai, Xing-Min; Hao, Yan-Qing; Zhang, Dong-Ping; Fan, Ping

    2009-10-01

    In this paper, InN thin films were deposited on Si (1 0 0) and K9 glass by reactive direct current magnetron sputtering. The target was In metal with the purity of 99.999% and the gases were Ar (99.999%) and N 2 (99.999%). The properties of InN thin films were studied. Scanning electron microscopy (SEM) shows that the film surface is very rough and energy dispersive X-ray spectroscopy (EDX) shows that the film contains In, N and very little O. X-ray diffraction (XRD) and Raman scattering reveal that the film mainly contains hexagonal InN. The four-probe measurement shows that InN film is conductive. The transmission measurement demonstrates that the transmission of InN deposited on K9 glass is as low as 0.5% from 400 nm to 800 nm.

  7. Morphology of epitaxial TiN(001) grown by magnetron sputtering

    SciTech Connect

    Karr, B.W.; Petrov, I.; Cahill, D.G.; Greene, J.E.

    1997-03-01

    The evolution of surface morphology and microstructure during growth of single crystal TiN(001) is characterized by {ital in situ} scanning tunneling microscopy and postdeposition plan-view transmission electron microscopy. The TiN layers are grown on MgO at 650{lt}T{lt}750{degree}C using reactive magnetron sputter deposition in pure N{sub 2}. The surface morphology is dominated by growth mounds with an aspect ratio of {approx_equal}0.006; both the roughness amplitude and average separation between mounds approximately follow a power law dependence on film thickness, t{sup {alpha}}, with {alpha}=0.25{plus_minus}0.07. Island edges show dendritic geometries characteristic of limited step-edge mobility at the growth temperature. {copyright} {ital 1997 American Institute of Physics.}

  8. Optical properties study of silicon oxynitride films deposited by RF magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Zhu, Yong; Gu, Peifu; Ye, Hui; Shen, Weidong

    2004-12-01

    Graded refractive index Silicon Oxy-nitride thin films were deposited by RF magnetron reactive sputtering at different N2/O2 flow ratio. The effects of gas flow ratio on the refractive index, extinction coefficient and composition were studied using UV-VIS spectrophotometer, XPS and FTIR characterization methods. A simple and accurate method is presented for determination of the optical constants and physical thickness of thin films. Which was consisted in fitting the experimental transmission curve with the help of the physical model. The relationship between composition and optical gap and dispersion energy was analyzed using Wemple DiDomenico single-oscillator model. As a result, the samples" refractive index can be controlled from 1.92 to 1.46 by adjusting the gas flow ratio, and the optical gap lies between 5eV~6.5eV.

  9. Very low pressure high power impulse triggered magnetron sputtering

    DOEpatents

    Anders, Andre; Andersson, Joakim

    2013-10-29

    A method and apparatus are described for very low pressure high powered magnetron sputtering of a coating onto a substrate. By the method of this invention, both substrate and coating target material are placed into an evacuable chamber, and the chamber pumped to vacuum. Thereafter a series of high impulse voltage pulses are applied to the target. Nearly simultaneously with each pulse, in one embodiment, a small cathodic arc source of the same material as the target is pulsed, triggering a plasma plume proximate to the surface of the target to thereby initiate the magnetron sputtering process. In another embodiment the plasma plume is generated using a pulsed laser aimed to strike an ablation target material positioned near the magnetron target surface.

  10. RF Magnetron Sputtering Deposited W/Ti Thin Film For Smart Window Applications

    NASA Astrophysics Data System (ADS)

    Oksuz, Lutfi; Kiristi, Melek; Bozduman, Ferhat; Uygun Oksuz, Aysegul

    2014-10-01

    Electrochromic (EC) devices can change reversible and persistent their optical properties in the visible region (400-800 nm) upon charge insertion/extraction according to the applied voltage. A complementary type EC is a device containing two electrochromic layers, one of which is anodically colored such as vanadium oxide (V2 O5) while the other cathodically colored such as tungsten oxide (WO3) which is separated by an ionic conduction layer (electrolyte). The use of a solid electrolyte such as Nafion eliminates the need for containment of the liquid electrolyte, which simplifies the cell design, as well as improves safety and durability. In this work, the EC device was fabricated on a ITO/glass slide. The WO3-TiO2 thin film was deposited by reactive RF magnetron sputtering using a 2-in W/Ti (9:1%wt) target with purity of 99.9% in a mixture gas of argon and oxygen. As a counter electrode layer, V2O5 film was deposited on an ITO/glass substrate using V2O3 target with the same conditions of reactive RF magnetron sputtering. Modified Nafion was used as an electrolyte to complete EC device. The transmittance spectra of the complementary EC device was measured by optical spectrophotometry when a voltage of +/-3 V was applied to the EC device by computer controlled system. The surface morphology of the films was characterized by scanning electron microscopy (SEM) and atomic force microscopy (AFM) (Fig. 2). The cyclic voltammetry (CV) for EC device was performed by sweeping the potential between +/-3 V at a scan rate of 50 mV/s.

  11. Magnetron sputtered boron films and TI/B multilayer structures

    DOEpatents

    Makowiecki, Daniel M.; Jankowski, Alan F.

    1993-01-01

    A method is described for the production of thin boron and titanium/boron films by magnetron sputter deposition. The amorphous boron films contain no morphological growth features, unlike those found when thin films are prepared by various physical vapor deposition processes. Magnetron sputter deposition method requires the use of a high density crystalline boron sputter target which is prepared by hot isostatic pressing. Thin boron films prepared by this method are useful for ultra-thin band pass filters as well as the low Z element in low Z/high Z mirrors which enhance reflectivity from grazing to normal incidence.

  12. Magnetron sputtered boron films and TI/B multilayer structures

    DOEpatents

    Makowiecki, D.M.; Jankowski, A.F.

    1993-04-20

    A method is described for the production of thin boron and titanium/boron films by magnetron sputter deposition. The amorphous boron films contain no morphological growth features, unlike those found when thin films are prepared by various physical vapor deposition processes. Magnetron sputter deposition method requires the use of a high density crystalline boron sputter target which is prepared by hot isostatic pressing. Thin boron films prepared by this method are useful for ultra-thin band pass filters as well as the low Z element in low Z/high Z mirrors which enhance reflectivity from grazing to normal incidence.

  13. Magnetron sputtered boron films and Ti/B multilayer structures

    DOEpatents

    Makowiecki, D.M.; Jankowski, A.F.

    1995-02-14

    A method is described for the production of thin boron and titanium/boron films by magnetron sputter deposition. The amorphous boron films contain no morphological growth features, unlike those found when thin films are prepared by various physical vapor deposition processes. Magnetron sputter deposition method requires the use of a high density crystalline boron sputter target which is prepared by hot isostatic pressing. Thin boron films prepared by this method are useful for ultra-thin band pass filters as well as the low Z element in low Z/high Z mirrors which enhance reflectivity from grazing to normal incidence. 6 figs.

  14. Magnetron sputtered boron films and Ti/B multilayer structures

    DOEpatents

    Makowiecki, Daniel M.; Jankowski, Alan F.

    1995-01-01

    A method is described for the production of thin boron and titanium/boron films by magnetron sputter deposition. The amorphous boron films contain no morphological growth features, unlike those found when thin films are prepared by various physical vapor deposition processes. Magnetron sputter deposition method requires the use of a high density crystalline boron sputter target which is prepared by hot isostatic pressing. Thin boron films prepared by this method are useful for ultra-thin band pass filters as well as the low Z element in low Z/high Z mirrors which enhance reflectivity from grazing to normal incidence.

  15. Plasma kinetics of Ar/O{sub 2} magnetron discharge by two-dimensional multifluid modeling

    SciTech Connect

    Costin, C.; Minea, T. M.; Popa, G.; Gousset, G.

    2010-03-15

    Multifluid two-dimensional model was developed to describe the plasma kinetics of the direct current Ar/O{sub 2} magnetron, coupling two modules: charged particles and neutrals. The first module deals with three positive ions - Ar{sup +}, O{sub 2}{sup +}, and O{sup +} - and two negative species - e{sup -} and O{sup -} - treated by the moments of Boltzmann's equation. The second one follows seven neutral species (Ar, O{sub 2}, O, O{sub 3}, and related metastables) by the multicomponent diffusion technique. The two modules are self-consistently coupled by the mass conservation and kinetic coefficients taking into account more than 100 volume reactions. The steady state is obtained when the overall convergence is achieved. Calculations for 10%O{sub 2} in Ar/O{sub 2} mixture at 2.67 and 4 Pa show that the oxygen excited species are mainly created by electron collisions in the negative glow of the discharge. Decreasing the pressure down to 0.67 Pa, the model reveals the nonlocal behavior of the reactive species. The density gradient of O{sub 2} ground state is reversed with respect to all gradients of the other reactive species, since the latter ones originate from the molecular ground state of oxygen. It is also found that the wall reactions drastically modify the space gradient of neutral reactive species, at least as much as the pressure, even if the discharge operates in compound mode.

  16. CONDENSED MATTER: ELECTRONIC STRUCTURE, ELECTRICAL, MAGNETIC, AND OPTICAL PROPERTIES: Effects of LSMO Buffer Layer on Crystalline Orientation and Ferroelectric Properties of Bi2.9Pr0.9Ti3O12 Thin Films Prepared by Radio-Frequency Magnetron Sputtering

    NASA Astrophysics Data System (ADS)

    Wu, Yun-Yi; Zhang, Duan-Ming; Yu, Jun; Zheng, Chao-Dan; Wang, Yun-Bo

    2008-11-01

    Ferroelectric Bi2.9Pr0.9Ti3O12/La0.67Sr0.33MnO3 (BPT/LSMO) films are fabricated on Pt(111)/TiO2/SiO2/Si substrates by rf-magnetron sputtering method. The influences of the LSMO deposition conditions and LSMO layer thickness on properties of BPT thin films are studied. The LSMO layer deposited at 300° C and 450σ C favours preferred (117) orientation of BPT films, while deposited at 600° C for LSMO layer leads to strong (111)-preferred orientation of BPT film. With the LSMO buffer layer, the films exhibit improved ferroelectric properties and Pt/BPT/LSMO(20nm)/Pt capacitor shows the largest remnant polarization Pr of 18.4 μC/cm2 at 14 V. A similar change in dielectric constant with the increase of LSMO layer thickness is also observed and the highest dielectric constant of 342.7 is obtained for the Pt/BPT/LSMO(20 nm)/Pt film. Compared with the Pt/BPT/Pt film, the Pt/BPT/LSMO/Pt films exhibit better fatigue endurance after 5 × 109 switching cycles. Moreover, the LSMO layer has apparent effect on leakage current density and the Pt/BPT/LSMO(20 nm)/Pt film exhibits the lowest leakage current density.

  17. A study of the transient plasma potential in a pulsed bi-polar dc magnetron discharge

    NASA Astrophysics Data System (ADS)

    Bradley, J. W.; Karkari, S. K.; Vetushka, A.

    2004-05-01

    The temporal evolution of the plasma potential, Vp, in a pulsed dc magnetron plasma has been determined using the emissive probe technique. The discharge was operated in the 'asymmetric bi-polar' mode, in which the discharge voltage changes polarity during part of the pulse cycle. The probe measurements, with a time-resolution of 20 ns or better, were made along a line above the racetrack, normal to the plane of the cathode target, for a fixed frequency (100 kHz), duty cycle (50%), argon pressure (0.74 Pa) and discharge power (583 W). At all the measured positions, Vp was found to respond to the large and rapid changes in the cathode voltage, Vd, during the different phases of the pulse cycle, with Vp always more positive than Vd. At a typical substrate position (>80 mm from the target), Vp remains a few volts above the most positive surface in the discharge at all times. In the 'on' phase of the pulse, the measurements show a significant axial electric field is generated in the plasma, with the plasma potential dropping by a total of about 30 V over a distance of 70 mm, from the bulk plasma to a position close to the beginning of the cathode fall. This is consistent with measurements made in the dc magnetron. During the stable 'reverse' phase of the discharge, for distances greater than 18 mm from the target, the axial electric field is found to collapse, with Vp elevated uniformly to about 3 V above Vd. Between the target and this field-free region an ion sheath forms, and the current flowing to the target is still an ion current in this 'reverse' period. During the initial 200 ns of the voltage 'overshoot' phase (between 'on' and 'reverse' phases), Vd reached a potential of +290 V; however, close to the target, Vp was found to attain a much higher value, namely +378 V. Along the line of measurement, the axial electric field reverses in direction in this phase, and an electron current of up to 9 A flows to the target. The spatial and temporal measurements of Vp

  18. Frequency analysis of functional immunoglobulin C- and V-gene expression by mitogen-reactive B cells in germfree mice fed chemically defined ultra-filtered "antigen-free" diet.

    PubMed

    Hooijkaas, H; van der Linde-Preesman, A A; Bitter, W M; Benner, R; Pleasants, J R; Wostmann, B S

    1985-04-01

    The frequencies of lipopolysaccharide (LPS)-reactive B cells and their antibody specificity repertoire have been determined in the spleen and bone marrow (BM) of conventional (CV) and "antigen-free" C3H/HeCr mice of various ages. The antigen-free mice were germfree (GF)-raised and were fed an ultrafiltered solution of chemically defined (CD) low m.w. nutrients, and were thus devoid of exogenous antigenic stimulation. Spleen and BM cells were grown in a limiting dilution culture system that allows the growth and development of every newly formed LPS-reactive B cell into a clone of IgM-secreting cells which are capable of switching to other immunoglobulin (Ig) heavy chain isotypes (C-gene expression). The secretion of IgM and IgG1 was determined in the protein A plaque assay, whereas specific IgM antibody-secreting cells (V-gene expression) were detected in plaque assays specific for various heterologous erythrocytes and sheep red blood cells (SRBC) coupled with a number of different haptens. The absolute frequency of LPS-reactive B cells and their capacity to switch to IgG1-secretion was not significantly different in 8- to 12-wk-old and 52-wk-old GF-CD mice and their age-matched CV controls. Moreover, no differences were observed in the frequencies of antigen-specific B cells within the pool of LPS reactive B cells. These frequencies ranged from 1 in 20 to 1 in 50 for NIP4-SRBC and NNP2-SRBC, from 1 in 100 to 1 in 150 for NIP0.4-SRBC, from 1 in 50 to 1 in 100 for TNP30-SRBC, and from 1 in 1000 to 1 in 2000 for SRBC and horse red blood cells. Within the limitations of having determined the switching capacity of IgM to IgG1 only and having assessed only a minor fraction of the total B cell antibody-specificity repertoire, the data indicate that young and old GF-CD mice, although devoid of exogenous antigenic and/or mitogenic stimulation, generate B cells with a similar switching capacity and a similar IgM antibody specificity repertoire as CV mice.

  19. On the target surface cleanness during magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Schelfhout, R.; Strijckmans, K.; Boydens, F.; Depla, D.

    2015-11-01

    The thickness of the chemisorbed oxide layer on a tantalum target surface was determined from sputter cleaning experiments. These measurements show a clear logarithmic growth behaviour as a function of the oxygen exposure. By extrapolating this result towards other sputter conditions, the target cleanness during magnetron sputter deposition can be estimated.

  20. Characterization of high power impulse magnetron sputtering discharges

    NASA Astrophysics Data System (ADS)

    Hala, Matej

    Paper I: In the first paper, we present a new approach in the characterization of the high power pulsed magnetron sputtering (HiPIMS) discharge evolution—time- and species-resolved plasma imaging—employing a set of band-pass optical interference filters suitable for the isolation of the emission originating from different species populating the plasma. We demonstrate that the introduction of such filters can be used to distinguish different phases of the discharge, and to visualize numerous plasma effects including background gas excitations during the discharge ignition, gas shock waves, and expansion of metal-rich plasmas. In particular, the application of this technique is shown on the diagnostics of the 200 µs long non-reactive HiPIMS discharges using a Cr target. Paper II: In order to gain further information about the dynamics of reactive HiPIMS discharges, both fast plasma imaging and time- and space-resolved optical emission spectroscopy (OES) are used for a systematic investigation of the 200 µs long HiPIMS pulses operated in Ar, N2 and N 2/Ar mixtures and at various pressures. It is observed that the dense metal plasma created next to the target propagates in the reactor at a speed ranging from 0.7 to 3.5 km s-1, depending on the working gas composition and the pressure. In fact, it increases with higher N 2 concentration and with lower pressure. The visible form of the propagating plasma wave changes from a hemispherical shape in Ar to a drop-like shape extending far from the target with increasing N2 concentration, owing to the significant emission from molecular N2. Interestingly, the evidence of the target self-sputtering is found for all investigated conditions, including pure N2 atmosphere. Paper III: Here, we report on the time- and species-resolved plasma imaging analysis of the dynamics of the 200 µs long HiPIMS discharges above a Cr target ignited in pure O2. It is shown that the discharge emission is dominated solely by neutral and

  1. The physical properties of AZO films deposited by RF magnetron sputtering in hydrogen-diluted argon

    NASA Astrophysics Data System (ADS)

    Kim, Jwayeon; Han, Jungsu; Jin, Hyunjoon; Kim, Youhyuk; Park, Kyeongsoon

    2014-08-01

    The properties of AZO (98-wt% ZnO, 2-wt% Al2O3) films produced in pure Ar and Ar (98%) + H2 (2%) (H2-diluted Ar) by radio-frequency (RF) magnetron sputtering were investigated as functions of the substrate temperatures. H2-diluted Ar improved the electrical properties of the AZO films fabricated at low substrate temperatures, but this benefit gradually diminished with increasing substrate temperature. This phenomenon was explained by O-H stretching in the Zn-O bond at low temperatures and by the formation of oxygen vacancies at high temperatures. The average optical transmission was over ~85%, and the orientation of the AZO films deposited both in pure Ar and in H2-diluted Ar was in the [002] direction.

  2. Bioactive glass thin films deposited by magnetron sputtering technique: The role of working pressure

    NASA Astrophysics Data System (ADS)

    Stan, G. E.; Marcov, D. A.; Pasuk, I.; Miculescu, F.; Pina, S.; Tulyaganov, D. U.; Ferreira, J. M. F.

    2010-09-01

    Bioglass coatings were prepared by radio frequency magnetron sputtering deposition at low temperature (150 °C) onto silicon substrates. The influence of argon pressure values used during deposition (0.2 Pa, 0.3 Pa and 0.4 Pa) on the short-range structure and biomineralization potential of the bioglass coatings was studied. The biomineralization capability was evaluated after 30 days of immersion in simulated body fluid. SEM-EDS, XRD and FTIR measurements were performed. The tests clearly showed strong biomineralization features for the bioglass films. The thickness of the chemically grown hydroxyapatite layers was more than twice greater for the BG films deposited at the highest working pressure, in comparison to those grown on the films obtained at lower working pressures. The paper attempts to explain this experimental fact based on structural and compositional considerations.

  3. Dielectric properties of tetragonal tungsten bronze films deposited by RF magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Bodeux, Romain; Michau, Dominique; Josse, Michaël; Maglione, Mario

    2014-12-01

    Tetragonal tungsten bronze (TTB) films have been synthesised on Pt(111)/TiO2/SiO2/Si substrates from Ba2LnFeNb4O15 ceramics (Ln = La, Nd, Eu) by RF magnetron sputtering. X-ray diffraction measurements evidenced the multi-oriented nature of films with some degrees of preferential orientation along (111). The dependence of the dielectric properties on temperature and frequency has been investigated. The dielectric properties of the films are similar to those of the bulk, i.e., ɛ ˜150 and σ ˜10-6 Ω-1 cm-1 at 1 MHz and room temperature. The films exhibit two dielectric anomalies which are attributed to Maxwell Wagner polarization mechanism and relaxor behaviour. Both anomalies are sensitive to post-annealing under oxygen atmosphere and their activation energies are similar Ea ˜0.30 eV. They are explained in terms of electrically heterogeneous contributions in the films.

  4. A new solid state extractor pulser for the FNAL magnetron ion source

    SciTech Connect

    Bollinger, D. S.; Lackey, J.; Larson, J.; Triplett, K.

    2015-10-05

    A new solid state extractor pulser has been installed on the Fermi National Accelerator Laboratory (FNAL) magnetron ion source, replacing a vacuum tube style pulser that was used for over 40 years. The required ion source extraction voltage is 35 kV for injection into the radio frequency quadrupole. At this voltage, the old pulser had a rise time of over 150 μs due to the current limit of the vacuum tube. The new solid state pulsers are capable of 50 kV, 100 A peak current pulses and have a rise time of 9 μs when installed in the operational system. This paper will discuss the pulser design and operational experience to date.

  5. A new solid state extractor pulser for the FNAL magnetron ion source

    SciTech Connect

    Bollinger, D. S. Lackey, J.; Larson, J.; Triplett, K.

    2016-02-15

    A new solid state extractor pulser has been installed on the Fermi National Accelerator Laboratory (FNAL) magnetron ion source, replacing a vacuum tube style pulser that was used for over 40 years. The required ion source extraction voltage is 35 kV for injection into the radio frequency quadrupole. At this voltage, the old pulser had a rise time of over 150 μs due to the current limit of the vacuum tube. The new solid state pulsers are capable of 50 kV, 100 A peak current pulses and have a rise time of 9 μs when installed in the operational system. This paper will discuss the pulser design and operational experience to date.

  6. Relativistic performance analysis of a high current density magnetron injection gun

    SciTech Connect

    Barnett, L. R.; Luhmann, N. C. Jr.; Chiu, C. C.; Chu, K. R.

    2009-09-15

    Electron beam quality is essential to the performance of millimeter-wave gyroamplifiers, particularly the gyrotron traveling-wave tube amplifier, which is extremely sensitive to the electron velocity spread and emission uniformity. As one moves up in power and frequency, the quality of the electron beam becomes even more critical. One aspect of the electron beam formation technology which has received relatively little attention has been the performance analysis of the electron beam itself. In this study, a 100 kV, 8 A magnetron injection gun with a calculated perpendicular-to-parallel velocity ratio of 1.4 and axial velocity spread of 3.5% has been designed, tested, and analyzed. It is shown that the equipment precision and a fully relativistic data analysis model afford sufficient resolution to allow a verification of the theoretical predictions as well as a quantitative inference to the surface roughness of the cathode used.

  7. [Spectrum diagnostics for the time of pre-sputtering in thin films deposited by magnetron puttering].

    PubMed

    Guo, Qing-Lin; Fan, Qing; Cui, Yong-Liang; Dong, Kai-Hu; Zhang, Lei; Li, Xu; Zhang, Jin-Ping; Chen, Jin-Zhong

    2013-03-01

    Abstract A plasma analysis system comprised of Omni-X300 series grating spectrometer, CCD data acquisition system and optical fiber transmission system was utilized in the present paper to realize the real-time acquisition of plasma emission spectra during the process of radio frequency (RF) magnetron sputtering. The plasma emission spectra produced by NiTa, TiAl ceramic targets and NiA1, TiA1 alloy targets were monitored respectively, in addition, the behavior of analysis lines of Ta I 333.991 nm, Ni I 362.473 nm, Al I 396.153 nm and Ti I 398.176 nm with time was obtained, according to which the time of pre-sputtering of the four kinds of target materials was fixed. At the same time, for the TiAl alloy target as the research object, the influence of different powers and pressures on the time of pre-sputtering was studied.

  8. Ion distribution measurements to probe target and plasma processes in electronegative magnetron discharges. II. Positive ions

    SciTech Connect

    Welzel, Th.; Ellmer, K.; Naumov, S.

    2011-04-01

    Spectra of the ion mass and energy distributions of positive ions in reactive (Ar/O{sub 2}) and nonreactive (Ar) dc magnetron sputtering discharges have been investigated by energy-resolved mass spectrometry. The results of three sputter target materials, i.e., Cu, In, and W are compared to each other. Besides the main gas constituents, mass spectra reveal a variety of molecular ions which are dependent on the target material. In reactive mode, ArO{sup +} is always observed in Ar/O{sub 2} but molecules containing Ar and the metal were exclusively found for the Cu target. The occurrence of the different ions is explained in the context of their bond strengths obtained from density functional theory calculations. The energy spectra generally contain the known low-energy peak corresponding to the plasma potential. Differently extended high-energy tails due to sputtered material were observed for the different targets. Besides these, high-energetic ions were detected with up to several 100 eV. Their energies are significantly different for Ar{sup +} and O{sup +} with Ar{sup +} strongly depending on the target material. The spectra are discussed together with results from transport of ions in matter (TRIM) calculation to elucidate the origin of these energetic ions.

  9. The role of Ohmic heating in dc magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Brenning, N.; Gudmundsson, J. T.; Lundin, D.; Minea, T.; Raadu, M. A.; Helmersson, U.

    2016-12-01

    Sustaining a plasma in a magnetron discharge requires energization of the plasma electrons. In this work, Ohmic heating of electrons outside the cathode sheath is demonstrated to be typically of the same order as sheath energization, and a simple physical explanation is given. We propose a generalized Thornton equation that includes both sheath energization and Ohmic heating of electrons. The secondary electron emission yield {γ\\text{SE}} is identified as the key parameter determining the relative importance of the two processes. For a conventional 5 cm diameter planar dc magnetron, Ohmic heating is found to be more important than sheath energization for secondary electron emission yields below around 0.1.

  10. Microwave beamed power technology improvement. [magnetrons and slotted waveguide arrays

    NASA Technical Reports Server (NTRS)

    Brown, W. C.

    1980-01-01

    The magnetron directional amplifier was tested for (1) phase shift and power output as a function of gain, anode current, and anode voltage, (2) background noise and harmonics in the output, (3) long life potential of the magnetron cathode, and (4) high operational efficiency. Examples of results were an adequate range of current and voltage over which 20 dB of amplification could be obtained, spectral noise density 155 dB below the carrier, 81.7% overall efficiency, and potential cathode life of 50 years in a design for solar power satellite use. A fabrication method was used to fabricate a 64 slot, 30 in square slotted waveguide array module from 0.020 in thick aluminum sheet. The test results on the array are discussed.

  11. Magnetron sputtering in rigid optical solar reflectors production

    NASA Astrophysics Data System (ADS)

    Asainov, O. Kh; Bainov, D. D.; Krivobokov, V. P.; Sidelev, D. V.

    2016-07-01

    Magnetron sputtering was applied to meet the growing need for glass optical solar reflectors. This plasma method provided more uniform deposition of the silver based coating on glass substrates resulted in decrease of defective reflectors fraction down to 5%. For instance, such parameter of resistive evaporation was of 30%. Silver film adhesion to glass substrate was enhanced with indium tin oxide sublayer. Sunlight absorption coefficient of these rigid reflectors was 0.081-0.083.

  12. Deposition of copper coatings in a magnetron with liquid target

    SciTech Connect

    Tumarkin, A. V. Kaziev, A. V.; Kolodko, D. V.; Pisarev, A. A.; Kharkov, M. M.; Khodachenko, G. V.

    2015-12-15

    Copper coatings were deposited on monocrystalline Si substrates using a magnetron discharge with a liquid cathode in the metal vapour plasma. During the deposition, the bias voltage in the range from 0 V to–400 V was applied to the substrate. The prepared films were investigated by a scanning electron microscope, and their adhesive properties were studied using a scratch tester. It was demonstrated that the adhesion of the deposited films strongly depends on the bias voltage and varies in a wide range.

  13. Passive mode control in the recirculating planar magnetron

    SciTech Connect

    Franzi, Matthew; Gilgenbach, Ronald; Lau, Y. Y.; Greening, Geoff; Zhang, Peng; Hoff, Brad

    2013-03-15

    Preliminary experiments of the recirculating planar magnetron microwave source have demonstrated that the device oscillates but is susceptible to intense mode competition due, in part, to poor coupling of RF fields between the two planar oscillators. A novel method of improving the cross-oscillator coupling has been simulated in the periodically slotted mode control cathode (MCC). The MCC, as opposed to a solid conductor, is designed to electromagnetically couple both planar oscillators by allowing for the propagation of RF fields and electrons through resonantly tuned gaps in the cathode. Using the MCC, a 12-cavity anode block with a simulated 1 GHz and 0.26 c phase velocity (where c is the speed of light) was able to achieve in-phase oscillations between the two sides of the device in as little as 30 ns. An analytic study of the modified resonant structure predicts the MCC's ability to direct the RF fields to provide tunable mode separation in the recirculating planar magnetron. The self-consistent solution is presented for both the degenerate even (in phase) and odd (180 Degree-Sign out of phase) modes that exist due to the twofold symmetry of the planar magnetrons.

  14. Method to control deposition rate instabilities—High power impulse magnetron sputtering deposition of TiO{sub 2}

    SciTech Connect

    Kossoy, Anna E-mail: anna.kossoy@gmail.com; Magnusson, Rögnvaldur L.; Tryggvason, Tryggvi K.; Leosson, Kristjan; Olafsson, Sveinn

    2015-03-15

    The authors describe how changes in shutter state (open/closed) affect sputter plasma conditions and stability of the deposition rate of Ti and TiO{sub 2} films. The films were grown by high power impulse magnetron sputtering in pure Ar and in Ar/O{sub 2} mixture from a metallic Ti target. The shutter state was found to have an effect on the pulse waveform for both pure Ar and reactive sputtering of Ti also affecting stability of TiO{sub 2} deposition rate. When the shutter opened, the shape of pulse current changed from rectangular to peak-plateau and pulse energy decreased. The authors attribute it to the change in plasma impedance and gas rarefaction originating in geometry change in front of the magnetron. TiO{sub 2} deposition rate was initially found to be high, 1.45 Å/s, and then dropped by ∼40% during the first 5 min, while for Ti the change was less obvious. Instability of deposition rate poses significant challenge for growing multilayer heterostructures. In this work, the authors suggest a way to overcome this by monitoring the integrated average energy involved in the deposition process. It is possible to calibrate and control the film thickness by monitoring the integrated pulse energy and end growth when desired integrated pulse energy level has been reached.

  15. Structure and properties of uranium oxide thin films deposited by pulsed dc magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Lin, Jianliang; Dahan, Isaac; Valderrama, Billy; Manuel, Michele V.

    2014-05-01

    Crystalline uranium oxide thin films were deposited in an unbalanced magnetron sputtering system by sputtering from a depleted uranium target in an Ar + O2 mixture using middle frequency pulsed dc magnetron sputtering. The substrate temperature was constantly maintained at 500 °C. Different uranium oxide phases (including UO2-x, UO2, U3O7 and U3O8) were obtained by controlling the percentage of the O2 flow rate to the total gas flow rate (f) in the chamber. The crystal structure of the films was characterized using X-ray diffraction and the microstructure of the films was studied using transmission electron microscopy and atom probe tomography. When the f was below 10%, the film contains a mixture of metallic uranium and UO2-x phases. As the f was controlled in the range of 10-13%, UO2 films with a (2 2 0) preferential orientation were obtained. The oxide phase rapidly changed to a mixture of U3O7 and U3O8 as the f was increased to the range of 15-18%. Further increasing the f to 20% and above, polycrystalline U3O8 thin films with a (0 0 1) preferential orientation were formed. The hardness and Young's modulus of the uranium oxide films were evaluated using nanoindentation. The film containing a single UO2 phase exhibited the maximum hardness of 14.3 GPa and a Young's modulus of 195 GPa. The UO2 thin film also exhibited good thermal stability in that no phase change was observed after annealing at 600 °C in vacuum for 104 h.

  16. Frequency of triggering bacteria in patients with reactive arthritis and undifferentiated oligoarthritis and the relative importance of the tests used for diagnosis

    PubMed Central

    Fendler, C; Laitko, S; Sorensen, H; Gripenberg-Lerche, C; Groh, A; Uksila, J; Granfors, K; Braun, J; Sieper, J

    2001-01-01

    OBJECTIVE—Reactive arthritis (ReA) triggered by Chlamydia trachomatis or enteric bacteria such as yersinia, salmonella, Campylobacter jejuni, or shigella is an important differential diagnosis in patients presenting with the clinical picture of an undifferentiated oligoarthritis (UOA). This study was undertaken to evaluate the best diagnostic approach.
PATIENTS AND METHODS—52 patients with ReA, defined by arthritis and a symptomatic preceding infection of the gut or the urogenital tract, and 74 patients with possible ReA, defined by oligoarthritis without a preceding symptomatic infection and after exclusion of other diagnoses (UOA), were studied. The following diagnostic tests were applied for the identification of the triggering bacterium: for yersinia induced ReA—stool culture, enzyme immunoassay (EIA), and Widal's agglutination test for detection of antibodies to yersinia; for salmonella or campylobacter induced ReA—stool culture, EIA for the detection of antibodies to salmonella and Campylobacter jejuni; for infections with shigella—stool culture; for infections with Chlamydia trachomatis—culture of the urogenital tract, microimmunofluorescence and immunoperoxidase assay for the detection of antibodies to Chlamydia trachomatis.
RESULTS—A causative pathogen was identified in 29/52 (56%) of all patients with ReA. In 17 (52%) of the patients with enteric ReA one of the enteric bacteria was identified: salmonella in 11/33 (33%) and yersinia in 6/33 (18%). Chlamydia trachomatis was the causative pathogen in 12/19 (63%) of the patients with urogenic ReA. In patients with the clinical picture of UOA a specific triggering bacterium was also identified in 35/74 (47%) patients: yersinia in 14/74 (19%), salmonella in 9/74 (12%), and Chlamydia trachomatis in 12/74 (16%).
CONCLUSIONS—Chlamydia trachomatis, yersinia, and salmonella can be identified as the causative pathogen in about 50% of patients with probable or possible ReA if the appropriate

  17. Medium-temperature solid oxide fuel cells prepared using reactive magnetron sputtering. Ph.D. Thesis

    SciTech Connect

    Wang, L.

    1993-12-31

    The purpose of this research is to investigate the deposition, structure, interfacial impedances, and characteristics of medium temperature solid-oxide fuel cells (SOFC`s) with thin-film electrolytes. Three main areas have been investigated. First, the structure, chemistry, and properties of materials designed specifically for medium temperature SOFC`s have been studied. The authors have developed techniques for sputter deposition of cubic 10 mol percent Y2O3-stabilized zirconia (YSZ) and 30 mol percent Y2O3-doped bismuth oxide (YSB) thin film oxygen ion conductors. The electrical properties of the films were characterized using the complex impedance spectroscopy method. Studies of AgYSZ cermet and Ag-perovskite (perovskite = La(1-x)Sr(x)Co(Mn)O3), used as high conductivity, low overpotential air electrodes, have also been carried out. Second, interfacial impedances for various electrode-electrolyte combinations and for multilayer electrolytes have been studied. In particular, the authors have found that a layer of Y-stabilized Bi2O3 (YSB) as thin as 60 nm between the YSZ electrolyte and the electrode significantly reduces the interfacial resistance. For example, inserting YSB between YSZ and a Ag-YSZ electrode reduces the resistance from 1.5 to 0.45 Omega cm(exp 2) at 750 deg C in air. Ag-(La,Sr)CoO3 on YSB electrolytes had interfacial resistances as low as 0.3 Omega cm2, compared with 0.4 and 1.5 Omega cm(exp 2) for (La,Sr)CoO3 and Ag on YSB at 750 deg C, respectively. The Ag cermet materials thus exhibited lower interfacial resistances than their component materials. Third, thin film medium temperature SOFC`s have been fabricated and characterized. SOFC`s were deposited onto porous alumina supports. The resulting cell open-circuit voltages (OCV) were approximately equal to 0.8 V, 0.3 V less than expected, due to gas cross-over.

  18. Heteroepitaxial growth of TiN film on MgO (100) by reactive magnetron sputtering.

    PubMed

    Chen, Wei-Chun; Peng, Chun-Yen; Chang, Li

    2014-01-01

    TiN thin films were deposited on MgO (100) substrates at different substrate temperatures using rf sputtering with Ar/N2 ratio of about 10. At 700°C, the growth rate of TiN was approximately 0.05 μm/h. The structural and electrical properties of TiN thin films were characterized with x-ray diffraction (XRD), atomic force microscopy (AFM), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and Hall measurements. For all deposition conditions, XRD results show that the TiN films can be in an epitaxy with MgO with cube-on-cube orientation relationship of (001)TiN // (001)MgO and [100]TiN // [100]MgO. TEM with selected-area electron diffraction pattern verifies the epitaxial growth of the TiN films on MgO. SEM and AFM show that the surface of the TiN film is very smooth with roughness approximately 0.26 nm. The minimum resistivity of the films can be as low as 45 μΩ cm.

  19. Separation behavior of impurities and selenium reduction by the reactive zone refining process using high-frequency induction heating to purify Te

    NASA Astrophysics Data System (ADS)

    Shim, Moonsoo; Kim, Young-Min; Lee, Huk-Hee; Hong, Soon-Jik; Lee, Jong-Hyeon

    2016-12-01

    A zone refining processing was utilized to purify tellurium (Te) metal using a locally melted zone caused by high-frequency induction heating. The travel rate of the molten zone was set as a parameter. The purification efficiency for each impurity (Bi, Sb, Sn, and Se) in the tellurium sample was analyzed by inductively coupled plasma optical emission spectroscopy (ICP-OES), and the experimental results were compared with the theoretical results furnished by the proposed model to validate its predictions. The experimental results indicated that a lower travel rate of the molten zone and repetition of passes were more efficient for purification. The effective distribution coefficient keff and the keff values of bismuth, antimony, tin, and selenium were 0.5, 0.35, 0.22, and 0.58, respectively. These elements were effective for the purification of Te by zone refining. The obtained distribution coefficient keff values of impurities can be used as standards for the purification of Te by zone refining. The Vickers hardness was measured, and a correlation between hardness and concentration was observed, with an average Vickers hardness was 62 Hv.

  20. Particle contamination formation and detection in magnetron sputtering processes

    SciTech Connect

    Selwyn, G.S.; Weiss, C.A.; Sequeda, F.; Huang, C.

    1996-10-01

    Defects caused by particulate contamination are an important concern in the fabrication of thin film products. Often, magnetron sputtering processes are used for this purpose. Particle contamination can cause electrical shorting, pin holes, problems with photolithography, adhesion failure, as well as visual and cosmetic defects. Particle contamination generated during thin film processing can be detected using laser light scattering, a powerful diagnostic technique that provides real-time, {ital in-situ} imaging of particles > 0.3 {mu}m in diameter. Using this technique, the causes, sources and influences on particles in plasma and non-plasma and non-plasma processes may be independently evaluated and corrected. Several studies employing laser light scattering have demonstrated both homogeneous and heterogeneous causes of particle contamination. In this paper, we demonstrate that the mechanisms for particle generation, transport and trapping during magnetron sputter deposition are different from the mechanisms reported in previously studied plasma etch processes. During magnetron sputter deposition, one source of particle contamination is linked to portions of the sputtering target surface exposed to weaker plasma density. In this region, film redeposition is followed by filament or nodule growth and enhanced trapping which increases filament growth. Eventually the filaments effectively ``short circuit`` the sheath, causing high currents to flow through these features. This, in turn, causes heating failure of the filament fracturing and ejecting the filaments into the plasma and onto the substrate. Evidence of this effect has been observed in semiconductor (IC) fabrication and storage disk manufacturing. Discovery of this mechanism in both technologies suggests that this mechanism may be universal to many sputtering processes.

  1. Plasma regimes in high power pulsed magnetron sputtering

    NASA Astrophysics Data System (ADS)

    de Los Arcos, Teresa

    2013-09-01

    High Power Pulsed Magnetron Sputtering (HPPMS) is a relatively recent variation of magnetron sputtering where high power is applied to the magnetron in short pulses. The result is the formation of dense transient plasmas with a high fraction of ionized species, ideally leading to better control of film growth through substrate bias. However, the broad range of experimental conditions accessible in pulsed discharges results in bewildering variations in current and voltage pulse shapes, pulse power densities, etc, which represent different discharge behaviors, making it difficult to identify relevant deposition conditions. The complexity of the plasma dynamics is evident. Within each pulse, plasma characteristics such as plasma composition, density, gas rarefaction, spatial distribution, degree of self-sputtering, etc. vary with time. A recent development has been the discovery that the plasma emission can self-organize into well-defined regions of high and low plasma emissivity above the racetrack (spokes), which rotate in the direction given by the E ×B drift and that significantly influence the transport mechanisms in HPPMS. One seemingly universal characteristic of HPPMS plasmas is the existence of well defined plasma regimes for different power ranges. These regimes are clearly differentiated in terms of plasma conductivity, plasma composition and spatial plasma self-organization. We will discuss the global characteristics of these regimes in terms of current-voltage characteristics, energy-resolved QMS and OES analysis, and fast imaging. In particular we will discuss how the reorganization of the plasma emission into spokes is associated only to specific regimes of high plasma conductivity. We will also briefly discuss the role of the target in shaping the characteristics of the HPPMS plasma, since sputtering is a surface-driven process. This work was supported by the Deutsche Forschungsgemeinschaft (DFG) within the framework of the SFB-TR87.

  2. Development of magnetron sputtering simulator with GPU parallel computing

    NASA Astrophysics Data System (ADS)

    Sohn, Ilyoup; Kim, Jihun; Bae, Junkyeong; Lee, Jinpil

    2014-12-01

    Sputtering devices are widely used in the semiconductor and display panel manufacturing process. Currently, a number of surface treatment applications using magnetron sputtering techniques are being used to improve the efficiency of the sputtering process, through the installation of magnets outside the vacuum chamber. Within the internal space of the low pressure chamber, plasma generated from the combination of a rarefied gas and an electric field is influenced interactively. Since the quality of the sputtering and deposition rate on the substrate is strongly dependent on the multi-physical phenomena of the plasma regime, numerical simulations using PIC-MCC (Particle In Cell, Monte Carlo Collision) should be employed to develop an efficient sputtering device. In this paper, the development of a magnetron sputtering simulator based on the PIC-MCC method and the associated numerical techniques are discussed. To solve the electric field equations in the 2-D Cartesian domain, a Poisson equation solver based on the FDM (Finite Differencing Method) is developed and coupled with the Monte Carlo Collision method to simulate the motion of gas particles influenced by an electric field. The magnetic field created from the permanent magnet installed outside the vacuum chamber is also numerically calculated using Biot-Savart's Law. All numerical methods employed in the present PIC code are validated by comparison with analytical and well-known commercial engineering software results, with all of the results showing good agreement. Finally, the developed PIC-MCC code is parallelized to be suitable for general purpose computing on graphics processing unit (GPGPU) acceleration, so as to reduce the large computation time which is generally required for particle simulations. The efficiency and accuracy of the GPGPU parallelized magnetron sputtering simulator are examined by comparison with the calculated results and computation times from the original serial code. It is found that

  3. Discharge current modes of high power impulse magnetron sputtering

    SciTech Connect

    Wu, Zhongzhen Xiao, Shu; Ma, Zhengyong; Cui, Suihan; Ji, Shunping; Pan, Feng; Tian, Xiubo; Fu, Ricky K. Y.; Chu, Paul K.

    2015-09-15

    Based on the production and disappearance of ions and electrons in the high power impulse magnetron sputtering plasma near the target, the expression of the discharge current is derived. Depending on the slope, six possible modes are deduced for the discharge current and the feasibility of each mode is discussed. The discharge parameters and target properties are simplified into the discharge voltage, sputtering yield, and ionization energy which mainly affect the discharge plasma. The relationship between these factors and the discharge current modes is also investigated.

  4. Magnetron co-sputtering system for coating ICF targets

    SciTech Connect

    Hsieh, E.J.; Meyer, S.F.; Halsey, W.G.; Jameson, G.T.; Wittmayer, F.J.

    1981-12-09

    Fabrication of Inertial Confinement Fusion (ICF) targets requires deposition of various types of coatings on microspheres. The mechanical strength, and surface finish of the coatings are of concern in ICF experiments. The tensile strength of coatings can be controlled through grain refinement, selective doping and alloy formation. We have constructed a magnetron co-sputtering system to produce variable density profile coatings with high tensile strength on microspheres. The preliminary data on the properties of a Au-Cu binary alloy system by SEM and STEM analysis is presented.

  5. Heteroepitaxial Ge-on-Si by DC magnetron sputtering

    SciTech Connect

    Steglich, Martin; Schrempel, Frank; Füchsel, Kevin; Kley, Ernst-Bernhard; Patzig, Christian; Berthold, Lutz; Höche, Thomas; Tünnermann, Andreas

    2013-07-15

    The growth of Ge on Si(100) by DC Magnetron Sputtering at various temperatures is studied by Spectroscopic Ellipsometry and Transmission Electron Microscopy. Smooth heteroepitaxial Ge films are prepared at relatively low temperatures of 380°C. Typical Stransky-Krastanov growth is observed at 410°C. At lower temperatures (320°C), films are essentially amorphous with isolated nanocrystallites at the Si-Ge interface. A minor oxygen contamination at the interface, developing after ex-situ oxide removal, is not seen to hinder epitaxy. Compensation of dislocation-induced acceptors in Ge by sputtering from n-doped targets is proposed.

  6. The Magnetron Method for the Determination of e/m for Electrons: Revisited

    ERIC Educational Resources Information Center

    Azooz, A. A.

    2007-01-01

    Additional information concerning the energy distribution function of electrons in a magnetron diode valve can be extracted. This distribution function is a manifestation of the effect of space charge at the anode. The electron energy distribution function in the magnetron is obtained from studying the variation of the anode current with the…

  7. Nanostructured phothocatalytic TiO2 thin film fabricated by magnetron sputtering on glass

    NASA Astrophysics Data System (ADS)

    Abdollahi Nejand, Bahram; Sanjabi, Sohrab; Ahmadi, Vahid

    TiO2 thin film was deposited by a DC reactive magnetron sputtering on ZnO/soda-lime glass substrate and single crystal SiO2 below 200 °C. ZnO layer was used as a buffer layer. Deposition was performed at Ar + O2 gas mixture with a pressure of 1.0 Pa and oxygen with a constant pressure of 0.2 Pa. The TiO2 / ZnO thicknesses were approximately 1000 nm and 80 nm, respectively. As-deposited films were annealed at 400 °C. The structure and morphology of deposited layers were evaluated by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The transmittance of the films was measured using ultraviolet-visible light (UV-vis) spectrophotometer. Photocatalytic activities of the samples were evaluated by the degradation of 2-propanol. The microstructure of annealed films was anatase, having improved photocatalytic activity. The surface grain size of TiO2 thin film after annealing was found about 25-35 nm and crystal size was approximately 8 nm. By using ZnO thin film as buffer layer, the photocatalytic property of TiO2 films was improved.

  8. Optical, structural, and mechanical properties of silicon oxynitride films prepared by pulsed magnetron sputtering.

    PubMed

    Tang, Chien-Jen; Jaing, Cheng-Chung; Tien, Chuen-Lin; Sun, Wei-Chiang; Lin, Shih-Chin

    2017-02-01

    Silicon oxynitride films were deposited by reactive pulsed magnetron sputtering. The optical, structural, and mechanical properties of silicon oxynitride films with different nitrogen proportions were analyzed via spectroscopy, atomic force microscopy, Twyman-Green interferometer, and nanoindentation. The refractive indices of the silicon oxynitride films were adjusted from 1.487 to 1.956 with the increase in nitrogen proportions. The surface roughness decreased from 1.33 to 0.97 nm with the increase in nitrogen proportions. The residual stress of the silicon oxynitride films was higher than for pure silicon nitride and silicon dioxide films. The hardness and Young's modulus increased from 13.51 to 19.74 GPa and 110.41 to 140.49 GPa with the increase in nitrogen proportions, respectively. The hardness and Young's modulus of antireflection coatings using silicon oxynitride film were 13.64 GPa and 102.11 GPa, respectively. Silicon oxynitride film could be used to improve the hardness of antireflective coatings.

  9. Rapidly switched wettability of titania films deposited by dc magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Shirolkar, Mandar; Kazemian Abyaneh, Majid; Singh, Akanksha; Tomer, Anju; Choudhary, Ram; Sathe, Vasant; Phase, Deodatta; Kulkarni, Sulabha

    2008-08-01

    Rapid switching (5-15 minutes) in the wettability of titania (TiO2) thin films in the anatase phase has been observed after UV irradiation. The film surface becomes superhydrophilic when exposed to UV radiation. The relationship between wettability, thickness and crystallinity of TiO2 films has been investigated. Amorphous and anatase TiO2 thin films have been deposited by varying the argon to oxygen gas ratio, using the reactive dc magnetron sputtering technique. It was found that the gas ratio primarily affects thickness, crystallinity, morphology and wettability of the films. The highest contact angle that has been reported so far, namely, 170°-176°, has been observed for film thickness varying from 112-500 nm in the case of pristine anatase TiO2 films. On the other hand, amorphous films show a variation in the contact angle from 120° to 140° as the thickness varied from 70 to 145 nm. The deposition is extremely robust and has an ultralow hysteresis in the contact angle. The films exhibit a morphology similar to the lotus leaf and the water hyacinth.

  10. Thermal stability and thermo-mechanical properties of magnetron sputtered Cr-Al-Y-N coatings

    SciTech Connect

    Rovere, Florian; Mayrhofer, Paul H.

    2008-01-15

    Cr{sub 1-x}Al{sub x}N coatings are promising candidates for advanced machining and high temperature applications due to their good mechanical and thermal properties. Recently the authors have shown that reactive magnetron sputtering using Cr-Al targets with Al/Cr ratios of 1.5 and Y contents of 0, 2, 4, and 8 at % results in the formation of stoichiometric (Cr{sub 1-x}Al{sub x}){sub 1-y}Y{sub y}N films with Al/Cr ratios of {approx}1.2 and YN mole fractions of 0%, 2%, 4%, and 8%, respectively. Here, the impact of Y on thermal stability, structural evolution, and thermo-mechanical properties is investigated in detail. Based on in situ stress measurements, thermal analyzing, x-ray diffraction, and transmission electron microscopy studies the authors conclude that Y effectively retards diffusional processes such as recovery, precipitation of hcp-AlN and fcc-YN, grain growth, and decomposition induced N{sub 2} release. Hence, the onset temperature of the latter shifts from {approx}1010 to 1125 deg. C and the hardness after annealing at T{sub a}=1100 deg. C increases from {approx}32 to 39 GPa with increasing YN mole fraction from 0% to 8%, respectively.

  11. Reducing the impurity incorporation from residual gas by ion bombardment during high vacuum magnetron sputtering

    SciTech Connect

    Rosen, Johanna; Widenkvist, Erika; Larsson, Karin; Kreissig, Ulrich; Mraz, Stanislav; Martinez, Carlos; Music, Denis; Schneider, J. M.

    2006-05-08

    The influence of ion energy on the hydrogen incorporation has been investigated for alumina thin films, deposited by reactive magnetron sputtering in an Ar/O{sub 2}/H{sub 2}O environment. Ar{sup +} with an average kinetic energy of {approx}5 eV was determined to be the dominating species in the plasma. The films were analyzed with x-ray diffraction, x-ray photoelectron spectroscopy, and elastic recoil detection analysis, demonstrating evidence for amorphous films with stoichiometric O/Al ratio. As the substrate bias potential was increased from -15 V (floating potential) to -100 V, the hydrogen content decreased by {approx}70%, from 9.1 to 2.8 at. %. Based on ab initio calculations, these results may be understood by thermodynamic principles, where a supply of energy enables surface diffusion, H{sub 2} formation, and desorption [Rosen et al., J. Phys.: Condens. Matter 17, L137 (2005)]. These findings are of importance for the understanding of the correlation between ion energy and film composition and also show a pathway to reduce impurity incorporation during film growth in a high vacuum ambient.

  12. C-axis orientated AlN films deposited using deep oscillation magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Lin, Jianliang; Chistyakov, Roman

    2017-02-01

    Highly <0001> c-axis orientated aluminum nitride (AlN) films were deposited on silicon (100) substrates by reactive deep oscillation magnetron sputtering (DOMS). No epitaxial favored bond layer and substrate heating were applied for assisting texture growth. The effects of the peak target current density (varied from 0.39 to 0.8 Acm-2) and film thickness (varied from 0.25 to 3.3 μm) on the c-axis orientation, microstructure, residual stress and mechanical properties of the AlN films were investigated by means of X-ray diffraction rocking curve methodology, transmission electron microscopy, optical profilometry, and nanoindentation. All AlN films exhibited a <0001> preferred orientation and compressive residual stresses. At similar film thicknesses, an increase in the peak target current density to 0.53 Acm-2 improved the <0001> orientation. Further increasing the peak target current density to above 0.53 Acm-2 showed limited contribution to the texture development. The study also showed that an increase in the thickness of the AlN films deposited by DOMS improved the c-axis alignment accompanied with a reduction in the residual stress.

  13. First demonstration and performance of an injection locked continuous wave magnetron to phase control a superconducting cavity

    SciTech Connect

    A.C. Dexter, G. Burt, R.G. Carter, I. Tahir, H. Wang, K. Davis, R. Rimmer

    2011-03-01

    The applications of magnetrons to high power proton and cw electron linacs are discussed. An experiment is described where a 2.45 GHz magnetron has been used to drive a single cell superconducting cavity. With the magnetron injection locked, a modest phase control accuracy of 0.95° rms has been demonstrated. Factors limiting performance have been identified.

  14. Fabrication and Electrical Characterization of the Si/ZnO/ZnO:Al Structure Deposited by RF-Magnetron Sputtering

    NASA Astrophysics Data System (ADS)

    Alaya, A.; Djessas, K.; El Mir, L.; Khirouni, K.

    2016-10-01

    The electrical transport properties of the structures of Si(p)/ZnO(i)/ZnO: Al(3%) and Si(p)/PS/ZnO(i)/ZnO: Al(3%) deposited by radio-frequency-magnetron sputtering were investigated and compared by using current-voltage and impedance spectroscopy measurements in a wide temperature range of 80-300 K. Aluminum-doped ZnO is considered to be one of the most important transparent conducting oxide materials due to its high conductivity, good transparency and low cost. From the current-voltage-temperature ( I- V- T) characteristics, it was found that both structures had a good rectifying behavior. This behavior decreases according to the porous silicon layer. The variation of the conductance with frequency indicates the semiconducting behavior and superposition of different conduction mechanisms. The insertion of the porous silicon layer results in a decrease of conductivity, which is attributed to reduced conductivity of defect-rich porous silicon.

  15. Closed field unbalanced magnetron sputtering ion plating of Ni/Al thin films: influence of the magnetron power.

    PubMed

    Said, R; Ahmed, W; Gracio, J

    2010-04-01

    In this study NiAl thin films have been deposited using closed field unbalanced magnetron sputtering Ion plating (CFUBMSIP). The influence of magnetron power has been investigated using dense and humongous NiAl compound targets onto stainless steel and glass substrates. Potential applications include tribological, electronic media and bond coatings in thermal barrier coatings system. Several techniques has been used to characterise the films including surface stylus profilometry, energy dispersive spectroscopy (EDAX), X-Ray diffraction (XRD) Composition analysis of the samples was carried out using VGTOF SIMS (IX23LS) and Atomic force microscopy (AFM). Scratch tester (CSM) combined with acoustic emission singles during loading in order to compare the coating adhesion. The acoustic emission signals emitted during the indentation process were used to determine the critical load, under which the film begins to crack and/or break off the substrate. The average thickness of the films was approximately 1 um. EDAX results of NiAl thin films coating with various magnetron power exhibited the near equal atomic% Ni:Al. The best result being obtained using 300 W and 400 W DC power for Ni and Al targets respectively. XRD revealed the presence of beta NiAl phase for all the films coatings. AFM analysis of the films deposited on glass substrates exhibited quite a smooth surface with surface roughness values in the nanometre range. CSM results indicate that best adhesion was achieved at 300 W for Ni, and 400 W for Al targets compared to sample other power values. SIMS depth profile showed a uniform distribution of the Ni and Al component from the surface of the film to the interface.

  16. Preparation and characterization of RF magnetron sputtered calcium pyrophosphate coatings.

    PubMed

    Yonggang, Yan; Wolke, J G C; Yubao, Li; Jansen, J A

    2006-03-15

    CaP ceramic has been widely used as coating on metals in orthopedics and oral dentistry. Variations in CaP composition can lead to different dissolution/precipitation behavior and may also affect the bone response. In the present study calcium pyrophosphate and hydroxylapatite coatings were successfully prepared by RF magnetron sputtering deposition. The phase composition, morphological properties, and the dissolution in SBF were characterized by using XRD, FTIR, EDS, SEM, and spectrophotometry. The results showed that all the sputtered coatings were amorphous and changed into a crystal structure after IR-radiation. The temperature for the crystallization of the amorphous coatings is lower for the hydroxylapatite coating (550 degrees C), compared to the calcium pyrophosphate coating (650 degrees C). All sputtered amorphous coatings were instable in SBF and dissolved partially within 4 wks of incubation. The heat-treated coatings appeared to be stable after incubation. These results showed that magnetron sputtering of calcium pyrophosphate coating is a promising method for forming a biocompatible ceramic coating.

  17. Double circular erosion patterns on dielectric target in magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Suzaki, Yoshifumi; Miyagawa, Hayato; Ejima, Seiki

    2009-10-01

    In rf magnetron sputtering, a circular erosion pattern forms on the surface of a circular metal conductor target with permanent magnets on its back. In this case, the theory behind the erosion pattern has been established. However, in the case of a dielectric target, a double circular erosion pattern is formed. So far, this pattern has been phenomenologically recognized by experimenters; however, it has not yet been investigated. In this study, we performed a magnetron sputtering experiment with a SiO2 dielectric target, and confirmed the formation of a double circular erosion pattern. The dimensions of the double circular erosion pattern varied depending on the insulation resistance or the thickness of the SiO2 target. Furthermore, we found that the dimensions of a double circular erosion pattern changed by making a gap between the SiO2 target and guard ring. Based on the experimental results, we have proposed a qualitative model to explain the formation mechanism of double circular erosion patterns.

  18. Asymmetric particle fluxes from drifting ionization zones in sputtering magnetrons

    NASA Astrophysics Data System (ADS)

    Panjan, Matjaž; Franz, Robert; Anders, André

    2014-04-01

    Electron and ion fluxes from direct current and high-power impulse magnetron sputtering (dcMS and HiPIMS) plasmas were measured in the plane of the target surface. Biased collector probes and a particle energy and mass analyzer showed asymmetric emission of electrons and of singly and doubly charged ions. For both HiPIMS and dcMS discharges, higher fluxes of all types of particles were observed in the direction of the electrons' E × B drift. These results are put in the context with ionization zones that drift over the magnetron's racetrack. The measured currents of time-resolving collector probes suggest that a large fraction of the ion flux originates from drifting ionization zones, while energy-resolving mass spectrometry indicates that a large fraction of the ion energy is due to acceleration by an electric field. This supports the recently proposed hypothesis that each ionization zone is associated with a negative-positive-negative space charge structure, thereby producing an electric field that accelerates ions from the location where they were formed.

  19. Plasma potential mapping of high power impulse magnetron sputtering discharges

    SciTech Connect

    Rauch, Albert; Mendelsberg, Rueben J.; Sanders, Jason M.; Anders, Andre

    2011-12-20

    Pulsed emissive probe techniques have been used to determine the plasma potential distribution of high power impulse magnetron sputtering (HiPIMS) discharges. An unbalanced magnetron with a niobium target in argon was investigated for pulse length of 100 μs at a pulse repetition rate of 100 Hz, giving a peak current of 170 A. The probe data were taken with a time resolution of 20 ns and a spatial resolution of 1 mm. It is shown that the local plasma potential varies greatly in space and time. The lowest potential was found over the target’s racetrack, gradually reaching anode potential (ground) several centimeters away from the target. The magnetic pre-sheath exhibits a funnel-shaped plasma potential resulting in an electric field which accelerates ions toward the racetrack. In certain regions and times, the potential exhibits weak local maxima which allow for ion acceleration to the substrate. Knowledge of the local E and static B fields lets us derive the electrons’ E×B drift velocity, which is about 105 m/s and shows structures in space and time.

  20. Reactive sintering and reactive hot

    NASA Astrophysics Data System (ADS)

    Murray, J. C.; German, R. M.

    1992-09-01

    NbAl3 has been synthesized from elemental powders by reactive sintering (RS) and reactive hot isostatic pressing (RHIP). Both processes involve a self-propagating exothermic reaction between the constituent powders to form an intermetallic compound. The RHIP approach uses simultaneous external pressurization to make a higher density product. This study focused on developing a method to use reactive synthesis to form high-density NbAl3 compacts. High RS and RHIP densities were possible with the appropriate raw materials and processing parameters. These include powder purity, particle sizes, degassing, heating rate, furnace temperature, and compaction pressures. Near full density was attained with RHIP, and up to 95 pct density was attained with RS.

  1. An inverted cylindrical sputter magnetron as metal vapor supply for electron cyclotron resonance ion sources

    SciTech Connect

    Weichsel, T. Hartung, U.; Kopte, T.; Zschornack, G.; Kreller, M.; Silze, A.

    2014-05-15

    An inverted cylindrical sputter magnetron device has been developed. The magnetron is acting as a metal vapor supply for an electron cyclotron resonance (ECR) ion source. FEM simulation of magnetic flux density was used to ensure that there is no critical interaction between both magnetic fields of magnetron and ECR ion source. Spatially resolved double Langmuir probe and optical emission spectroscopy measurements show an increase in electron density by one order of magnitude from 1 × 10{sup 10} cm{sup −3} to 1 × 10{sup 11} cm{sup −3}, when the magnetron plasma is exposed to the magnetic mirror field of the ECR ion source. Electron density enhancement is also indicated by magnetron plasma emission photography with a CCD camera. Furthermore, photographs visualize the formation of a localized loss-cone - area, when the magnetron is operated at magnetic mirror field conditions. The inverted cylindrical magnetron supplies a metal atom load rate of R > 1 × 10{sup 18} atoms/s for aluminum, which meets the demand for the production of a milliampere Al{sup +} ion beam.

  2. An inverted cylindrical sputter magnetron as metal vapor supply for electron cyclotron resonance ion sources.

    PubMed

    Weichsel, T; Hartung, U; Kopte, T; Zschornack, G; Kreller, M; Silze, A

    2014-05-01

    An inverted cylindrical sputter magnetron device has been developed. The magnetron is acting as a metal vapor supply for an electron cyclotron resonance (ECR) ion source. FEM simulation of magnetic flux density was used to ensure that there is no critical interaction between both magnetic fields of magnetron and ECR ion source. Spatially resolved double Langmuir probe and optical emission spectroscopy measurements show an increase in electron density by one order of magnitude from 1 × 10(10) cm(-3) to 1 × 10(11) cm(-3), when the magnetron plasma is exposed to the magnetic mirror field of the ECR ion source. Electron density enhancement is also indicated by magnetron plasma emission photography with a CCD camera. Furthermore, photographs visualize the formation of a localized loss-cone - area, when the magnetron is operated at magnetic mirror field conditions. The inverted cylindrical magnetron supplies a metal atom load rate of R > 1 × 10(18) atoms/s for aluminum, which meets the demand for the production of a milliampere Al(+) ion beam.

  3. Characteristics of reactively sputtered niobium nitride thin films as diffusion barriers for Cu metallization

    NASA Astrophysics Data System (ADS)

    Huang, Cheng-Lin; Lai, Chih-Huang; Tsai, Po-Hao; Huang, Hsing-An; Lin, Jing-Cheng; Lee, Chiapyng

    2013-09-01

    NbN films were prepared by radio frequency reactive magnetron sputtering and then employed as diffusion barriers between Cu and Si. The microstructure of the NbN films was an assembly of very small columnar crystallites with a cubic structure. To investigate the properties as diffusion barriers, we performed metallurgical reactions of Cu/NbN0.8/Si, Cu/Nb/Si and Cu/TaN0.7/Si for comparisons. The sheet resistance increased dramatically after annealing above 750°C for Cu/NbN0.80/Si, and above 500°C for both Cu/Nb/Si and Cu/TaN0.7/Si. The interfaces were deteriorated seriously and formation of Cu3Si was observed when the sheet resistance was significantly increased. The diffusion coefficient of Cu in NbN barrier films was estimated by using the change of resistance (Δ R s / R s %). Compared with TaN0.7, NbN0.8 films possess larger grain size and lower Cu diffusion coefficient. Our results suggest that the NbN film can be used as a diffusion barrier for Cu metallization as compared to the well-known TaN film.

  4. Simulation Study Using an Injection Phase-locked Magnetron as an Alternative Source for SRF Accelerators

    SciTech Connect

    Wang, Haipeng; Plawski, Tomasz E.; Rimmer, Robert A.

    2015-09-01

    As a drop-in replacement for the CEBAF CW klystron system, a 1497 MHz, CW-type high-efficiency magnetron using injection phase lock and amplitude variation is attractive. Amplitude control using magnetic field trimming and anode voltage modulation has been studied using analytical models and MATLAB/Simulink simulations. Since the 1497 MHz magnetron has not been built yet, previously measured characteristics of a 2.45GHz cooker magnetron are used as reference. The results of linear responses to the amplitude and phase control of a superconducting RF (SRF) cavity, and the expected overall benefit for the current CEBAF and future MEIC RF systems are presented in this paper.

  5. Characterization on RF magnetron sputtered niobium pentoxide thin films

    SciTech Connect

    Usha, N.; Sivakumar, R.; Sanjeeviraja, C.

    2014-10-15

    Niobium pentoxide (Nb{sub 2}O{sub 5}) thin films with amorphous nature were deposited on microscopic glass substrates at 100°C by rf magnetron sputtering technique. The effect of rf power on the structural, morphological, optical, and vibrational properties of Nb{sub 2}O{sub 5} films have been investigated. Optical study shows the maximum average transmittance of about 87% and the optical energy band gap (indirect allowed) changes between 3.70 eV and 3.47 eV. AFM result indicates the smooth surface nature of the samples. Photoluminescence measurement showed the better optical quality of the deposited films. Raman spectra show the LO-TO splitting of Nb-O stretching of Nb{sub 2}O{sub 5} films.

  6. GaAs Films Prepared by RF-Magnetron Sputtering

    SciTech Connect

    L.H. Ouyang; D.L. Rode; T. Zulkifli; B. Abraham-Shrauner; N. Lewis; M.R. Freeman

    2001-08-01

    The authors reported on the optical absorption, adhesion, and microstructure of RF-magnetron sputtered films of hydrogenated amorphous and microcrystalline GaAs films for the 1 to 25 {micro}m infrared wavelength rate. Sputtering parameters which were varied include sputtering power, temperature and pressure, and hydrogen sputtering-gas concentration. TEM results show a sharp transition from purely amorphous GaAs to a mixture of microcrystalline GaAs in an amorphous matrix at 34 {+-} 2 C. By optimizing the sputtering parameters, the optical absorption coefficient can be decreased below 100 cm{sup -1} for wavelengths greater than about 1.25 {micro}m. These results represent the lowest reported values of optical absorption for sputtered films of GaAs directly measured by spectrophotometry for the near-infrared wavelength region.

  7. Influence of RF power on magnetron sputtered AZO films

    SciTech Connect

    Agarwal, Mohit; Modi, Pankaj; Dusane, R. O.

    2013-02-05

    Al-doped Zinc Oxide (AZO) transparent conducting films are prepared on glass substrate by RF magnetron sputtering under different RF power with a 3 inch diameter target of 2 wt%Al{sub 2}O{sub 3} in zinc oxide. The effect of RF power on the structural, optical and electrical properties of AZO films was investigated by X-ray Diffraction (XRD), Hall measurement and UV-Visible spectrophotometry. The XRD data indicates a preferential c-axis orientation for all the films. All films exhibit high transmittance (<90%) in visible region. Films deposited at 60 W power exhibit lowest resistivity of 5.7 Multiplication-Sign 10{sup -4}{omega}cm. Such low-resistivity and high-transmittance AZO films when prepared using low RF power at room temperature could find important applications in flexible electronics.

  8. Magnetron with flux switching cathode and method of operation

    DOEpatents

    Aaron, David B.; Wiley, John D.

    1989-01-01

    A magnetron sputtering apparatus is formed with a plurality of cells each for generating an independent magnetic field within a different region in the chamber of the apparatus. Each magnetic field aids in maintaining an ion plasma in the respective region of the chamber. One of a plurality of sputtering material targets is positioned on an electrode adjacent to each region so that said ions strike the target ejecting some of the target material. By selectively generating each magnetic field, the ion plasma may be moved from region to region to sputter material from different targets. The sputtered material becomes deposited on a substrate mounted on another electrode within the chamber. The duty cycle of each cell can be dynamically varied during the deposition to produce a layer having a graded composition throughout its thickness.

  9. Magnetron with flux switching cathode and method of operation

    DOEpatents

    Aaron, D.B.; Wiley, J.D.

    1989-09-12

    A magnetron sputtering apparatus is formed with a plurality of cells each for generating an independent magnetic field within a different region in the chamber of the apparatus. Each magnetic field aids in maintaining an ion plasma in the respective region of the chamber. One of a plurality of sputtering material targets is positioned on an electrode adjacent to each region so that said ions strike the target ejecting some of the target material. By selectively generating each magnetic field, the ion plasma may be moved from region to region to sputter material from different targets. The sputtered material becomes deposited on a substrate mounted on another electrode within the chamber. The duty cycle of each cell can be dynamically varied during the deposition to produce a layer having a graded composition throughout its thickness. 5 figs.

  10. Resputtering effect during MgO buffer layer deposition by magnetron sputtering for superconducting coated conductors

    SciTech Connect

    Xiao, Shaozhu; Shi, Kai; Deng, Shutong; Han, Zhenghe; Feng, Feng Lu, Hongyuan; Qu, Timing; Zhu, Yuping; Huang, Rongxia

    2015-07-15

    In this study, MgO thin films were deposited by radio-frequency magnetron sputtering. The film thickness in the deposition area directly facing the target center obviously decreased compared with that in other areas. This reduction in thickness could be attributed to the resputtering effect resulting from bombardment by energetic particles mainly comprising oxygen atoms and negative oxygen ions. The influences of deposition position and sputtering pressure on the deposition rate were investigated. Resputtering altered the orientation of the MgO film from (111) to (001) when the film was deposited on a single crystal yttria-stabilized zirconia substrate. The density distribution of energetic particles was calculated on the basis of the measured thicknesses of the MgO films deposited at different positions. The divergence angle of the energetic particle flux was estimated to be approximately 15°. The energetic particle flux might be similar to the assisting ion flux in the ion beam assisted deposition process and could affect the orientation of the MgO film growth.

  11. Effects of Various RF Powers on CdTe Thin Film Growth Using RF Magnetron Sputtering

    NASA Astrophysics Data System (ADS)

    Alibakhshi, Mohammad; Ghorannevis, Zohreh

    2016-09-01

    Cadmium telluride (CdTe) film was deposited using the magnetron sputtering system onto a glass substrate at various deposition times and radio frequency (RF) powers. Ar gas was used to generate plasma to sputter the CdTe atoms from CdTe target. Effects of two experimental parameters of deposition time and RF power were investigated on the physical properties of the CdTe films. X-ray Diffraction (XRD) analysis showed that the films exhibited polycrystalline nature of CdTe structure with the (111) orientation as the most prominent peak. Optimum condition to grow the CdTe film was obtained and it was found that increasing the deposition time and RF power increases the crystallinity of the films. From the profilometer and XRD data's, the thicknesses and crystal sizes of the CdTe films increased at the higher RF power and the longer deposition time, which results in affecting the band gap as well. From atomic force microscopy (AFM) analysis we found that roughnesses of the films depend on the deposition time and is independent of the RF power.

  12. Fractal features of CdTe thin films grown by RF magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Hosseinpanahi, Fayegh; Raoufi, Davood; Ranjbarghanei, Khadijeh; Karimi, Bayan; Babaei, Reza; Hasani, Ebrahim

    2015-12-01

    Cadmium telluride (CdTe) thin films were prepared by RF magnetron sputtering on glass substrates at room temperature (RT). The film deposition was performed for 5, 10, and 15 min at power of 30 W with a frequency of 13.56 MHz. The crystal structure of the prepared CdTe thin films was studied by X-ray diffraction (XRD) technique. XRD analyses indicate that the CdTe films are polycrystalline, having zinc blende structure of CdTe irrespective of their deposition time. All CdTe films showed a preferred orientation along (1 1 1) crystalline plane. The surface morphology characterization of the films was studied using atomic force microscopy (AFM). The quantitative AFM characterization shows that the RMS surface roughness of the prepared CdTe thin films increases with increasing the deposition time. The detrended fluctuation analysis (DFA) and also multifractal detrended fluctuation analysis (MFDFA) methods showed that prepared CdTe thin films have multifractal nature. The complexity, roughness of the CdTe thin films and strength of the multifractality increase as deposition time increases.

  13. Superior biofunctionality of dental implant fixtures uniformly coated with durable bioglass films by magnetron sputtering.

    PubMed

    Popa, A C; Stan, G E; Enculescu, M; Tanase, C; Tulyaganov, D U; Ferreira, J M F

    2015-11-01

    Bioactive glasses are currently considered the suitable candidates to stir the quest for a new generation of osseous implants with superior biological/functional performance. In congruence with this vision, this contribution aims to introduce a reliable technological recipe for coating fairly complex 3D-shaped implants (e.g. dental screws) with uniform and mechanical resistant bioactive glass films by the radio-frequency magnetron sputtering method. The mechanical reliability of the bioactive glass films applied to real Ti dental implant fixtures has been evaluated by a procedure comprised of "cold" implantation in pig mandibular bone from a dead animal, followed by immediate tension-free extraction tests. The effects of the complex mechanical strains occurring during implantation were analysed by scanning electron microscopy coupled with electron dispersive spectroscopy. Extensive biocompatibility assays (MTS, immunofluorescence, Western blot) revealed that the bioactive glass films stimulated strong cellular adhesion and proliferation of human dental pulp stem cells, without promoting their differentiation. The ability of the implant coatings to conserve a healthy stem cell pool is promising to further endorse the fabrication of new osseointegration implant designs with extended lifetime.

  14. Modeling of RF Magnetron Plasma in N2 with dielectric target

    NASA Astrophysics Data System (ADS)

    Arbeltier, Steven; Revel, Adrien; Sabary, Frédéric; Secouard, Christophe; Minea, Tiberiu

    2016-09-01

    Thin film batteries technology requires a solid electrolyte suitable for its operation. One option is to use LiPON deposited from Li3PO4 target by radio frequency magnetron sputtering in nitrogen plasma. Despite the successful implementation of this technology, the processes occurring into the plasma and at the substrate during deposition need to be well understood. Modelling is an interesting approach to study the undergoing phenomena such as the quantification of plasma species, the potential evolution in the reactor, the shape of the racetrack and the trajectories of sputtered species. The present results are obtained from two models, (i) a 0D model which describes the plasma kinetic and (ii) a 2D model assuming the axial symmetry. The latter uses a Particle-In-Cell Monte-Carlo approach and self-consistently describes the plasma creation and charged particles trajectories in the reactor. The geometry and the magnetic field correspond to a real CEA-LETI reactor .The dielectric target is 6'' diameter. Radiofrequency polarization of the target is taken into account in the model. Results on the evolution of ions density in plasma, the electric-field and the self-bias on the target, are discussed.

  15. Fabrication and physico-mechanical properties of thin magnetron sputter deposited silver-containing hydroxyapatite films

    NASA Astrophysics Data System (ADS)

    Ivanova, A. A.; Surmeneva, M. A.; Tyurin, A. I.; Pirozhkova, T. S.; Shuvarin, I. A.; Prymak, O.; Epple, M.; Chaikina, M. V.; Surmenev, R. A.

    2016-01-01

    As a measure of the prevention of implant associated infections, a number of strategies have been recently applied. Silver-containing materials possessing antibacterial activity as expected might have wide applications in orthopedics and dentistry. The present work focuses on the physico-chemical characterization of silver-containing hydroxyapatite (Ag-HA) coating obtained by radio frequency (RF) magnetron sputtering. Mechanochemically synthesized Ag-HA powder (Ca10⿿xAgx(PO4)6(OH)2⿿x, x = 1.5) was used as a precursor for sputtering target preparation. Morphology, composition, crystallinity, physico-mechanical features (Young's modulus and nanohardness) of the deposited Ag-HA coatings were investigated. The sputtering of the nanostructured multicomponent target at the applied process conditions allowed to deposit crystalline Ag-HA coating which was confirmed by XRD and FTIR data. The SEM results revealed the formation of the coating with the grain morphology and columnar cross-section structure. The EDX analysis confirmed that Ag-HA coating contained Ca, P, O and Ag with the Ca/P ratio of 1.6 ± 0.1. The evolution of the mechanical properties allowed to conclude that addition of silver to HA film caused increase of the coating nanohardness and elastic modulus compared with those of pure HA thin films deposited under the same deposition conditions.

  16. Investigation of annealing temperature effect on magnetron sputtered cadmium sulfide thin film properties

    NASA Astrophysics Data System (ADS)

    Akbarnejad, E.; Ghorannevis, Z.; Abbasi, F.; Ghoranneviss, M.

    2016-12-01

    Cadmium sulfide (CdS) thin films are deposited on the fluorine doped tin oxide coated glass substrate using the radio frequency magnetron sputtering setup. The effects of annealing in air on the structural, morphological, and optical properties of CdS thin film are studied. Optimal annealing temperature is investigated by annealing the CdS thin film at different annealing temperatures of 300, 400, and 500 °C. Thin films of CdS are characterized by X-ray diffractometer analysis, field emission scanning electron microscopy, atomic force microscopy, UV-Vis-NIR spectrophotometer and four point probe. The as-grown CdS films are found to be polycrystalline in nature with a mixture of cubic and hexagonal phases. By increasing the annealing temperature to 500 °C, CdS film showed cubic phase, indicating the phase transition of CdS. It is found from physical characterizations that the heat treatment in air increased the mean grain size, the transmission, and the surface roughness of the CdS thin film, which are desired to the application in solar cells as a window layer material.

  17. Three-Dimensional, Fibrous Lithium Iron Phosphate Structures Deposited by Magnetron Sputtering.

    PubMed

    Bünting, Aiko; Uhlenbruck, Sven; Sebold, Doris; Buchkremer, H P; Vaßen, R

    2015-10-14

    Crystalline, three-dimensional (3D) structured lithium iron phosphate (LiFePO4) thin films with additional carbon are fabricated by a radio frequency (RF) magnetron-sputtering process in a single step. The 3D structured thin films are obtained at deposition temperatures of 600 °C and deposition times longer than 60 min by using a conventional sputtering setup. In contrast to glancing angle deposition (GLAD) techniques, no tilting of the substrate is required. Thin films are characterized by X-ray diffraction (XRD), Raman spectrospcopy, scanning electron microscopy (SEM), cyclic voltammetry (CV), and galvanostatic charging and discharging. The structured LiFePO4+C thin films consist of fibers that grow perpendicular to the substrate surface. The fibers have diameters up to 500 nm and crystallize in the desired olivine structure. The 3D structured thin films have superior electrochemical properties compared with dense two-dimensional (2D) LiFePO4 thin films and are, hence, very promising for application in 3D microbatteries.

  18. Effects of the duty ratio on the niobium oxide film deposited by pulsed-DC magnetron sputtering methods.

    PubMed

    Eom, Ji Mi; Oh, Hyun Gon; Cho, Il Hwan; Kwon, Sang Jik; Cho, Eou Sik

    2013-11-01

    Niobium oxide (Nb2O5) films were deposited on p-type Si wafers and sodalime glasses at a room temperature using in-line pulsed-DC magnetron sputtering system with various duty ratios. The different duty ratio was obtained by varying the reverse voltage time of pulsed DC power from 0.5 to 2.0 micros at the fixed frequency of 200 kHz. From the structural and optical characteristics of the sputtered NbOx films, it was possible to obtain more uniform and coherent NbOx films in case of the higher reverse voltage time as a result of the cleaning effect on the Nb2O5 target surface. The electrical characteristics from the metal-insulator-semiconductor (MIS) fabricated with the NbOx films shows the leakage currents are influenced by the reverse voltage time and the Schottky barrier diode characteristics.

  19. Effect of Sputtering Temperature on Structure and Optical Properties of NiO Films Fabricated by Magnetron Sputtering

    NASA Astrophysics Data System (ADS)

    Wang, Hui; Zhao, Yang; Li, Xinzhong; Zhen, Zhiqiang; Li, Hehe; Wang, Jingge; Tang, Miaomiao

    2017-03-01

    NiO thin films were deposited on sapphire and Corning 1737 glass substrates using the radio frequency magnetron sputtering system. The structures, optical and electrical properties of NiO films grown under different sputtering temperatures were thoroughly studied. The NiO films were composed of different-size NiO nano-grains with a strong (111) preferred orientation. The NiO grain size increased with the sputtering temperature increase. The band gap values decreased from 3.69 eV to 3.38 eV on the sputtering temperature increase from 30°C to 450°C. Moreover, the electrical property variations of the NiO samples were studied by the Hall effect in detail.

  20. What Is Reactive Arthritis?

    MedlinePlus

    ... Arthritis PDF Version Size: 69 KB November 2014 What is Reactive Arthritis? Fast Facts: An Easy-to- ... Information About Reactive Arthritis and Other Related Conditions What Causes Reactive Arthritis? Sometimes, reactive arthritis is set ...

  1. The Impact of Accelerated Right Prefrontal High-Frequency Repetitive Transcranial Magnetic Stimulation (rTMS) on Cue-Reactivity: An fMRI Study on Craving in Recently Detoxified Alcohol-Dependent Patients

    PubMed Central

    Herremans, Sarah C.; Van Schuerbeek, Peter; De Raedt, Rudi; Matthys, Frieda; Buyl, Ronald; De Mey, Johan; Baeken, Chris

    2015-01-01

    In alcohol-dependent patients craving is a difficult-to-treat phenomenon. It has been suggested that high-frequency (HF) repetitive transcranial magnetic stimulation (rTMS) may have beneficial effects. However, exactly how this application exerts its effect on the underlying craving neurocircuit is currently unclear. In an effort to induce alcohol craving and to maximize detection of HF-rTMS effects to cue-induced alcohol craving, patients were exposed to a block and event-related alcohol cue-reactivity paradigm while being scanned with fMRI. Hence, we assessed the effect of right dorsolateral prefrontal cortex (DLPFC) stimulation on cue-induced and general alcohol craving, and the related craving neurocircuit. Twenty-six recently detoxified alcohol-dependent patients were included. First, we evaluated the impact of one sham-controlled stimulation session. Second, we examined the effect of accelerated right DLPFC HF-rTMS treatment: here patients received 15 sessions in an open label accelerated design, spread over 4 consecutive days. General craving significantly decreased after 15 active HF-rTMS sessions. However, cue-induced alcohol craving was not altered. Our brain imaging results did not show that the cue-exposure affected the underlying craving neurocircuit after both one and fifteen active HF-rTMS sessions. Yet, brain activation changes after one and 15 HF-rTMS sessions, respectively, were observed in regions associated with the extended reward system and the default mode network, but only during the presentation of the event-related paradigm. Our findings indicate that accelerated HF-rTMS applied to the right DLPFC does not manifestly affect the craving neurocircuit during an alcohol-related cue-exposure, but instead it may influence the attentional network. PMID:26295336

  2. High quality boron carbon nitride/ZnO-nanorods p-n heterojunctions based on magnetron sputtered boron carbon nitride films

    SciTech Connect

    Qian, J. C.; Jha, S. K. E-mail: apwjzh@cityu.edu.hk; Wang, B. Q.; Jelenković, E. V.; Bello, I.; Klemberg-Sapieha, J. E.; Martinu, L.; Zhang, W. J. E-mail: apwjzh@cityu.edu.hk

    2014-11-10

    Boron carbon nitride (BCN) films were synthesized on Si (100) and fused silica substrates by radio-frequency magnetron sputtering from a B{sub 4}C target in an Ar/N{sub 2} gas mixture. The BCN films were amorphous, and they exhibited an optical band gap of ∼1.0 eV and p-type conductivity. The BCN films were over-coated with ZnO nanorod arrays using hydrothermal synthesis to form BCN/ZnO-nanorods p-n heterojunctions, exhibiting a rectification ratio of 1500 at bias voltages of ±5 V.

  3. A Compact, Pi-Mode Extraction Scheme for the Axial B-Field Recirculating Planar Magnetron

    DTIC Science & Technology

    2012-07-23

    Figure 4). Thus, in a planar magnetron, the minimum phase velocity, vph , to stay above cutoff in the rectangular waveguide is ℎ = ...as magnetrons, electrons must be accelerated such that they are in synchronism with the phase velocity, vph , of the electromagnetic wave for an...is also likely to be a factor in the waveguide power-loading profile data displayed in Figure 10 (a). It is expected that a careful optimization of

  4. Radio-frequency magnetron triode sputtering of cadmium telluride and zinc telluride films and solar cells

    NASA Astrophysics Data System (ADS)

    Sanford, Adam Lee

    The n-CdS/p-CdTe solar cell has been researched for many years now. Research groups use a variety of processes to fabricate thin-film CdS/CdTe cells, including physical vapor deposition, chemical vapor deposition, and RF diode sputtering. One of the central areas of investigation concerning CdS/CdTe cells is the problem of a Schottky barrier at the back contact. Even cells fabricated with ohmic back contacts degrade into Schottky barriers as the devices are used. This severely degrades power generation. One possible solution is to use p+-ZnTe as an interlayer between CdTe and the back contact. ZnTe is easily doped with Cu to be p-type. However, even contacts with this ZnTe interlayer degrade over time, because Cu is highly mobile and diffuses away from the contact towards the CdS/CdTe junction. Another possibility is to dope ZnTe with N. It has been demonstrated using molecular beam epitaxy and RF diode sputtering. In this study, CdTe films are fabricated using a variation of RF diode sputtering called triode sputtering. This technique allows for control of ion bombardment to the substrate during deposition. Also, a higher plasma density near the target is achieved allowing depositions at lower pressures. These films are characterized structurally to show the effects of the various deposition parameters. N-doped ZnTe films are also fabricated using this technique. These films are characterized electrically to show the effects of the various deposition parameters. Also, the effects of post-deposition annealing are observed. It is found that annealing at the right temperature can increase the conductivity of the films by a factor of 3 or more. However, annealing at higher temperatures decreases the conductivity to as low as 12% of the initial conductivity. Finally, RF triode sputtered N-doped ZnTe films are used as an interlayer at the back contact of a CdS/CdTe solar cell. The effects of annealing the device before and after contact deposition are observed. Annealing before depositing contacts results in an increase in Voc of 20mV. Annealing after contact deposition results in a degradation of fill factor over time.

  5. DEPOSITION OF NIOBIUM AND OTHER SUPERCONDUCTING MATERIALS WITH HIGH POWER IMPULSE MAGNETRON SPUTTERING: CONCEPT AND FIRST RESULTS

    SciTech Connect

    High Current Electronics Institute, Tomsk, Russia; Anders, Andre; Mendelsberg, Rueben J.; Lim, Sunnie; Mentink, Matthijs; Slack, Jonathan L.; Wallig, Joseph G.; Nollau, Alexander V.; Yushkov, Georgy Yu.

    2011-07-24

    Niobium coatings on copper cavities have been considered as a cost-efficient replacement of bulk niobium RF cavities, however, coatings made by magnetron sputtering have not quite lived up to high expectations due to Q-slope and other issues. High power impulse magnetron sputtering (HIPIMS) is a promising emerging coatings technology which combines magnetron sputtering with a pulsed power approach. The magnetron is turned into a metal plasma source by using very high peak power density of ~ 1 kW/cm{sup 2}. In this contribution, the cavity coatings concept with HIPIMS is explained. A system with two cylindrical, movable magnetrons was set up with custom magnetrons small enough to be inserted into 1.3 GHz cavities. Preliminary data on niobium HIPIMS plasma and the resulting coatings are presented. The HIPIMS approach has the potential to be extended to film systems beyond niobium, including other superconducting materials and/or multilayer systems.

  6. The bioactivity mechanism of magnetron sputtered bioglass thin films

    NASA Astrophysics Data System (ADS)

    Berbecaru, C.; Stan, G. E.; Pina, S.; Tulyaganov, D. U.; Ferreira, J. M. F.

    2012-10-01

    Smooth and adherent bioactive coatings with ∼0.5 μm thickness were deposited onto Si substrates by the radiofrequency-magnetron sputtering method at 150 °C under 0.4 Pa of Ar atmosphere using a bioglass powder as target with a composition in the SiO2-CaO-MgO-P2O5-CaF2-B2O3-Na2O system. The bioactivity of the as-prepared bioglass samples was assessed by immersion in simulated body fluid for different periods of time up to 30 days. Grazing incidence X-ray diffraction, Fourier transform infra-red spectrometry and energy dispersive spectroscopy revealed that important structural and compositional changes took place upon immersing the samples in SBF. Whilst the excellent biomineralisation capability of the BG thin films was demonstrated by the in vitro induction of extensive and homogenous crystalline hydroxyapatite in-growths on their surfaces, a series of bioactivity process kinetics peculiarities (derogations from the classical model) were emphasised and thoroughly discussed.

  7. Discharge Physics of High Power Impulse Magnetron Sputtering

    SciTech Connect

    Anders, Andre

    2010-10-13

    High power impulse magnetron sputtering (HIPIMS) is pulsed sputtering where the peak power exceeds the time-averaged power by typically two orders of magnitude. The peak power density, averaged over the target area, can reach or exceed 107 W/m2, leading to plasma conditions that make ionization of the sputtered atoms very likely. A brief review of HIPIMS operation is given in a tutorial manner, illustrated by some original data related to the self-sputtering of niobium in argon and krypton. Emphasis is put on the current-voltage-time relationships near the threshold of self-sputtering runaway. The great variety of current pulse shapes delivers clues on the very strong gas rarefaction, self-sputtering runaway conditions, and the stopping of runaway due to the evolution of atom ionization and ion return probabilities as the gas plasma is replaced by metal plasma. The discussions are completed by considering instabilities and the special case of ?gasless? self-sputtering.

  8. Electron transport in magnetrons by a posteriori Monte Carlo simulations

    NASA Astrophysics Data System (ADS)

    Costin, C.; Minea, T. M.; Popa, G.

    2014-02-01

    Electron transport across magnetic barriers is crucial in all magnetized plasmas. It governs not only the plasma parameters in the volume, but also the fluxes of charged particles towards the electrodes and walls. It is particularly important in high-power impulse magnetron sputtering (HiPIMS) reactors, influencing the quality of the deposited thin films, since this type of discharge is characterized by an increased ionization fraction of the sputtered material. Transport coefficients of electron clouds released both from the cathode and from several locations in the discharge volume are calculated for a HiPIMS discharge with pre-ionization operated in argon at 0.67 Pa and for very short pulses (few µs) using the a posteriori Monte Carlo simulation technique. For this type of discharge electron transport is characterized by strong temporal and spatial dependence. Both drift velocity and diffusion coefficient depend on the releasing position of the electron cloud. They exhibit minimum values at the centre of the race-track for the secondary electrons released from the cathode. The diffusion coefficient of the same electrons increases from 2 to 4 times when the cathode voltage is doubled, in the first 1.5 µs of the pulse. These parameters are discussed with respect to empirical Bohm diffusion.

  9. Plasma parameters of an active cathode during relativistic magnetron operation

    NASA Astrophysics Data System (ADS)

    Hadas, Y.; Kweller, T.; Sayapin, A.; Krasik, Ya. E.; Bernshtam, V.

    2009-09-01

    The results of time- and space-resolved spectroscopic studies of the plasma produced at the surface of the ferroelectric cathode during the operation of an S-band relativistic magnetron generating ˜50 MW microwave power at f =3005 MHz and powered by a linear induction accelerator (LIA) (150 kV, 1.5 kA, 250 ns) are presented. The surface plasma was produced by a driving pulse (3 kV, 150 ns) prior to the application of the LIA accelerating high-voltage pulse. The cathode plasma electron density and temperature were obtained by analyzing hydrogen Hα and Hβ, and carbon ions CII and CIII spectral lines, and using the results of nonstationary collision radiative modeling. It was shown that the microwave generation causes an increase in plasma ion and electron temperature up to ˜4 and ˜7 eV, respectively, and the plasma density increases up to ˜7×1014 cm-3. Estimates of the plasma transport parameters and its interaction with microwave radiation are also discussed.

  10. Magnetron-sputtered Be coatings as reflectors for ultracold neutrons

    NASA Astrophysics Data System (ADS)

    Bryś, T.; Daum, M.; Fierlinger, P.; Fomin, A.; Geltenbort, P.; Henneck, R.; Kirch, K.; Kharitonov, A.; Krasnoshekova, I.; Kuźniak, M.; Lasakov, M.; Pichlmaier, A.; Raimondi, F.; Schelldorfer, R.; Serebrov, A.; Siber, E.; Tal'daev, R.; Varlamov, V.; Vasiliev, A.; Wambach, J.; Zherebtsov, O.

    2005-10-01

    We describe the production, characterization and performance of magnetron-sputtered Be coatings on aluminum, copper and stainless steel substrates. The coating thickness is typically 300 nm. Small samples were characterized by means of Optical Microscopy (OM), Atomic Force Microscopy (AFM) and X-ray induced Photoelectron Spectroscopy (XPS) and Elastic Recoil Detection Analysis (ERDA). The coating quality and adhesion following thermal cycling and neutron irradiation were tested with respect to future applications as storage containers in Ultracold Neutron (UCN) sources. The fractional uncoated area was determined to be 10 -4 to 10 -5 by OM and XPS. These results were confirmed by foil transmission measurements with UCN in the energy range 180 to 230 neV. The storage time of a 250 l Be-coated Cu container was determined for UCN energies up to 60 neV at room temperature and around 90 K and the wall loss factor η extracted. We obtained η (90 K)=2.7×10 -5 and η(300 K)=1.1×10 -4 in good agreement with previously published results.

  11. Langmuir probe measurements in the Hollow Cathode Magnetron

    NASA Astrophysics Data System (ADS)

    Vukovic, Mirko; Lai, Kwok-Fai

    1997-10-01

    The Hollow Cathode Magnetron (HCM) is a new kind of a high density plasma device which has been proposed as an ionized physical vapor deposition source for semiconductor device fabrication(John C. Helmer, Kwok F. Lai, Robert L. Anderson US Patent 5,482,661, Jan. 9, 1996). The target is of high purity metal machined to resemble a hollow cathode (id. 4cm, depth 6cm). It resides in a cooled metal housing. The magnetic field (several hundred Gauss) is generated by permanent magnets stacked on the outside of the metal housing, aligned parallel to the HCM axis. At the mouth of the HCM, a magnetic cusp traps a high density plasma. Beyond the cusp, a slowly diverging magnetic field produces a low temperature (T_e ~ 2-3eV), high density (n_e ~ 10^12-10^13cm-3∝ P_DC) plume. The HCM serves to both sputter and ionize metal atoms from the target. These ions may deposit onto a silicon device wafer, enabling metal deposition into the bottom of very small (<0.5μm) high aspect ratio (>=6:1) features. The unique properties of the films deposited using the HCM will be presented and related to the plasma parameters obtained from Langmuir probe data and magnetic field modeling. discharge is on the inside wall

  12. Influence of plasma-generated negative oxygen ion impingement on magnetron sputtered amorphous SiO{sub 2} thin films during growth at low temperatures

    SciTech Connect

    Macias-Montero, M.; Garcia-Garcia, F. J.; Alvarez, R.; Gil-Rostra, J.; Gonzalez, J. C.; Gonzalez-Elipe, A. R.; Palmero, A.; Cotrino, J.

    2012-03-01

    Growth of amorphous SiO{sub 2} thin films deposited by reactive magnetron sputtering at low temperatures has been studied under different oxygen partial pressure conditions. Film microstructures varied from coalescent vertical column-like to homogeneous compact microstructures, possessing all similar refractive indexes. A discussion on the process responsible for the different microstructures is carried out focusing on the influence of (i) the surface shadowing mechanism, (ii) the positive ion impingement on the film, and (iii) the negative ion impingement. We conclude that only the trend followed by the latter and, in particular, the impingement of O{sup -} ions with kinetic energies between 20 and 200 eV, agrees with the resulting microstructural changes. Overall, it is also demonstrated that there are two main microstructuring regimes in the growth of amorphous SiO{sub 2} thin films by magnetron sputtering at low temperatures, controlled by the amount of O{sub 2} in the deposition reactor, which stem from the competition between surface shadowing and ion-induced adatom surface mobility.

  13. Particle beam experiments for the analysis of reactive sputtering processes in metals and polymer surfaces.

    PubMed

    Corbella, Carles; Grosse-Kreul, Simon; Kreiter, Oliver; de los Arcos, Teresa; Benedikt, Jan; von Keudell, Achim

    2013-10-01

    A beam experiment is presented to study heterogeneous reactions relevant to plasma-surface interactions in reactive sputtering applications. Atom and ion sources are focused onto the sample to expose it to quantified beams of oxygen, nitrogen, hydrogen, noble gas ions, and metal vapor. The heterogeneous surface processes are monitored in situ by means of a quartz crystal microbalance and Fourier transform infrared spectroscopy. Two examples illustrate the capabilities of the particle beam setup: oxidation and nitriding of aluminum as a model of target poisoning during reactive magnetron sputtering, and plasma pre-treatment of polymers (PET, PP).

  14. The 'reactive

    NASA Astrophysics Data System (ADS)

    Battista Piccardo, Giovanni; Guarnieri, Luisa

    2010-05-01

    The Ligurian ophiolitic peridotites [South Lanzo, Erro-Tobbio, Internal Ligurides and Corsica] are characterized by the abundance of spinel(Sp) peridotites showing depleted compositions and ranging from Cpx-poor Sp lherzolites to Sp harzburgites. They were recognized in the last decades as refractory residua by MORB-forming partial melting of the asthenosphere, and were similar to abyssal peridotites. Recent structural and compositional studies promoted a better understanding of their structural and compositional features and their genetic processes. In the field these depleted peridotites replace with primary contacts pyroxenite-bearing fertile Sp lherzolites that have been recognized as sub-continental lithospheric mantle. Field relationships evidence that decametric-hectometric bodies of pristine pyroxenite-veined lithospheric Sp lherzolites are preserved as structural remnants within the km-scale masses of depleted peridotites. The depleted peridotites show coarse-grained recrystallized textures and reaction micro-structures indicating pyroxene dissolution and olivine precipitation that have been considered as records of melt/peridotite interaction during reactive diffuse porous flow of undersaturated melts. They show, moreover, contrasting bulk and mineral chemistries that cannot be produced by simple partial melting and melt extraction. In particular, their bulk compositions are depleted in SiO2 and enriched in FeO with respect to refractory residua after any kind of partial melting, as calculated by Niu (1997), indicating that they cannot be formed by simple partial melting and melt extraction processes. Moreover, TiO2 content in Sp is usually significantly higher (up to 0.8-1.0 wt%) than typical TiO2 contents of spinels (usually < 0.1-0.2 wt %) in fertile mantle peridotites and melting refractory residua, indicating that spinel attained element equilibration with a Ti-bearing basaltic melt. The depleted peridotites usually show strongly variable Cpx modal

  15. Hybrid biocomposite with a tunable antibacterial activity and bioactivity based on RF magnetron sputter deposited coating and silver nanoparticles

    NASA Astrophysics Data System (ADS)

    Ivanova, A. A.; Surmenev, R. A.; Surmeneva, M. A.; Mukhametkaliyev, T.; Loza, K.; Prymak, O.; Epple, M.

    2015-02-01

    In this work, we describe fabrication techniques used to prepare a multifunctional biocomposite based on a hydroxyapatite (HA) coating and silver nanoparticles (AgNPs). AgNPs synthesized by a wet chemical reduction method were deposited on Ti substrates using a dripping/drying method followed by deposition of calcium phosphate (CaP) coating via radio-frequency (RF) magnetron sputter-deposition. The negatively charged silver nanoparticles (zeta potential -21 mV) have a spherical shape with a metallic core diameter of 50 ± 20 nm. The HA coating was deposited as a dense nanocrystalline film over a surface of AgNPs. The RF-magnetron sputter deposition of HA films on the AgNPs layer did not affect the initial content of AgNPs on the substrate surface as well as NPs size and shape. SEM cross-sectional images taken using the backscattering mode revealed a homogeneous layer of AgNPs under the CaP layer. The diffraction patterns from the coatings revealed reflexes of crystalline HA and silver. The concentration of Ag ions released from the biocomposites after 7 days of immersion in phosphate and acetate buffers was estimated. The obtained results revealed that the amount of silver in the solutions was 0.27 ± 0.02 μg mL-1 and 0.54 ± 0.02 μg mL-1 for the phosphate and acetate buffers, respectively, which corresponded well with the minimum inhibitory concentration range known for silver ions in literature. Thus, this work establishes a new route to prepare a biocompatible layer using embedded AgNPs to achieve a local antibacterial effect.

  16. Correlation of photothermal conversion on the photo-induced deformation of amorphous carbon nitride films prepared by reactive sputtering

    SciTech Connect

    Harata, T.; Aono, M. Kitazawa, N.; Watanabe, Y.

    2014-08-04

    The photo-induced deformation of hydrogen-free amorphous carbon nitride (a-CN{sub x}) films was investigated under visible-light illumination. The films gave rise to photothermal conversion by irradiation. In this study, we investigated the effects of thermal energy generated by irradiation on the deformation of a-CN{sub x}/ultrathin substrate bimorph specimens. The films were prepared on both ultrathin Si and SiO{sub 2} substrates by reactive radio-frequency magnetron sputtering from a graphite target in the presence of pure nitrogen gas. The temperature of the film on the SiO{sub 2} substrate increased as the optical band-gap of the a-CN{sub x} was decreased. For the film on Si, the temperature remained constant. The deformation degree of the films on Si and SiO{sub 2} substrates were approximately the same. Thus, the deformation of a-CN{sub x} films primarily induced by photon energy directly.

  17. Growth of CuCl thin films by magnetron sputtering for ultraviolet optoelectronic applications

    SciTech Connect

    Natarajan, Gomathi; Daniels, S.; Cameron, D. C.; O'Reilly, L.; Mitra, A.; McNally, P. J.; Lucas, O. F.; Rajendra Kumar, R. T.; Reid, Ian; Bradley, A. L.

    2006-08-01

    Copper (I) chloride (CuCl) is a potential candidate for ultraviolet (UV) optoelectronics due to its close lattice match with Si (mismatch less than 0.4%) and a high UV excitonic emission at room temperature. CuCl thin films were deposited using radio frequency magnetron sputtering technique. The influence of target to substrate distance (d{sub ts}) and sputtering pressure on the composition, microstructure, and UV emission properties of the films were analyzed. The films deposited with shorter target to substrate spacing (d{sub ts}=3 cm) were found to be nonstoichiometric, and the film stoichiometry improves when the substrate is moved away from the target (d{sub ts}=4.5 and 6 cm). A further increase in the spacing results in poor crystalline quality. The grain interface area increases when the sputtering pressure is increased from 1.1x10{sup -3} to 1x10{sup -2} mbar at d{sub ts}=6 cm. Room temperature cathodoluminescence spectrum shows an intense and sharp UV exciton (Z{sub 3}) emission at {approx}385 nm with a full width at half maximum of 16 nm for the films deposited at the optimum d{sub ts} of 6 cm and a pressure of 1.1x10{sup -3} mbar. A broad deep level emission in the green region ({approx}515 nm) is also observed. The relative intensity of the UV to green emission peaks decreased when the sputtering pressure was increased, consistent with an increase in grain boundary area. The variation in the stoichiometry and the crystallinity are attributed to the change in the intensity and energy of the flux of materials from the target due to the interaction with the background gas molecules.

  18. Physical properties of rf magnetron sputter deposited NiO:WO3 thin films

    NASA Astrophysics Data System (ADS)

    Usha, K. S.; Sivakumar, R.; Sanjeeviraja, C.; Ichimura, M.

    2015-01-01

    The present study describes various physical properties of mixed nickel-tungsten oxide (NiO:WO3) (95:5) thin films prepared on glass substrate by rf magnetron sputtering due to the variation in rf power (100, 150, and 200 W). X-ray diffraction study shows that all the deposited films are amorphous in nature. The maximum transmittance of 97% in the infrared region was observed for the film deposited at 100 W rf power. A systematic reduction in the optical band gap is observed with increasing rf power, which is associated with the rf power induced effect leading to the production of localized states near the band edges of NiO:WO3. The Urbach energy (EU) value was found to increase with rf power, which may be due to the increased defects in the NiO matrix. From the optical study, we have evaluated various parameters such as refractive index, packing density, lattice dielectric constant, ratio between free carrier density and free carrier effective mass, plasma frequency, and dispersion energy parameters, etc. These results are discussed and correlated well with the light of possible mechanisms underlying the phenomena. The compositional purity of the film was confirmed by energy dispersive x-ray analysis (EDAX) and Auger electron spectroscopic (AES) measurements. The Raman spectra of NiO:WO3 films show two peaks corresponding to one-phonon LO mode at 560 cm-1 and two-phonon LO mode at 1100 cm-1 due to the vibrations of Ni-O bonds and a strong peak at 860 cm-1 corresponds to the stretching vibration of W-O pair in the WO6 group. The band edge emission at 369 nm was observed in photoluminescence spectra.

  19. Cue Reactivity as a Predictor of Drinking among Male Alcoholics.

    ERIC Educational Resources Information Center

    Rohsenow, Damaris J.; And Others

    1994-01-01

    Alcoholic men (n=45) admitted for detoxification to treatment program underwent cue reactivity assessment protocol, and 91% received three-month follow-up interviews. Greater salivary reactivity predicted greater frequency of drinking during follow-up. Greater attention to stimulus or to response predicting less drinking. Cue reactivity did not…

  20. OPTICAL PROPERTIES OF N-DOPED Cu2O THIN FILMS DEPOSITED BY RF-MAGNETRON SPUTTERING Cu2O TARGET

    NASA Astrophysics Data System (ADS)

    Lai, Guozhong; Wu, Yangwei; Lin, Limei; Qu, Yan; Lai, Fachun

    2014-05-01

    N-doped Cu2O films were deposited on quartz substrates by reactive magnetron sputtering a Cu2O target. The optical constants and thicknesses of the films with different nitrogen partial pressure (NPP) were retrieved from transmittance data by an optical model which combines the Forouhi-Bloomer model with modified Drude model. The results show that when NPP increases from 0.0 to 0.033 Pa, the optical gap decreases from 2.14 to 1.95 eV. Additionally, an optical absorption process in the infrared region below the optical band gap was observed for N-doped Cu2O films, which was not found in the pure Cu2O film. This is because an intermediate band (IB) in the band gap results from nitrogen doping. It is believed that N-doped Cu2O film with suitable NPP could be used to enhance the energy conversion efficiency for photovoltaic cells.

  1. Substrate Heating Effect on c-Axis Texture and Piezoelectric Properties of AlN Thin Films Deposited by Unbalanced Magnetron Sputtering

    NASA Astrophysics Data System (ADS)

    Hasheminiasari, Masood; Lin, Jianliang

    2016-06-01

    Aluminum nitride (AlN) thin films with highly preferred (002) orientations have been reactively deposited by a pulsed-closed field unbalanced magnetron sputtering system using TiN/Ti as the seed/adhesion layer with various substrate temperatures. The texture, orientation and piezoelectric properties of AlN films were characterized by means of x-ray diffraction, rocking curves and laser interferometry. A Michelson laser interferometer was designed and built to obtain the converse piezoelectric response of the deposited AlN thin films. It was found that a slight substrate temperature increase would significantly affect the (002) orientation and the piezoelectric coefficient of AlN thin films compared to the coating obtained with no intentional substrate heating, while higher temperature applications on substrate deteriorated the c-axis texture of the coatings without significant improvement in the piezoelectric response of AlN films.

  2. Surface modification of tantalum pentoxide coatings deposited by magnetron sputtering and correlation with cell adhesion and proliferation in in vitro tests

    NASA Astrophysics Data System (ADS)

    Zykova, A.; Safonov, V.; Goltsev, A.; Dubrava, T.; Rossokha, I.; Donkov, N.; Yakovin, S.; Kolesnikov, D.; Goncharov, I.; Georgieva, V.

    2016-03-01

    The effect was analyzed of surface treatment by argon ions on the surface properties of tantalum pentoxide coatings deposited by reactive magnetron sputtering. The structural parameters of the as-deposited coatings were investigated by means of transmission electron microscopy, atomic force microscopy and scanning electron microscopy. X-ray diffraction profiles and X-ray photoelectron spectra were also acquired. The total surface free energy (SFE), the polar, dispersion parts and fractional polarities, were estimated by the Owens-Wendt-Rabel-Kaeble method. The adhesive and proliferative potentials of bone marrow cells were evaluated for both Ta2O5 coatings and Ta2O5 coatings deposited by simultaneous bombardment by argon ions in in vitro tests.

  3. Microwave impedance matching strategies of an applicator supplied by a bi-directional magnetron waveguide launcher.

    PubMed

    Roussy, Georges; Kongmark, Nils

    2003-01-01

    It is shown that a bi-directional waveguide launcher can be used advantageously for reducing the reflection coefficient mismatch of an input impedance of an applicator. In a simple bi-directional waveguide launcher, the magnetron is placed in the waveguide and generates a nominal field distribution with significant output impedance in both directions of the waveguide. If a standing wave is tolerated in the torus, which connects the launcher and the applicator, the power transfer from the magnetron to the applicator can be optimal, without using special matching devices. It is also possible to match the bi-directional launcher with two inductance stubs near the antenna of the magnetron and use them for supplying a two-input applicator without reflection.

  4. Solid-state pulse modulator for a 1.7-MW X-band magnetron

    NASA Astrophysics Data System (ADS)

    Choi, Jaegu; Shin, Yong-Moon; Choi, Young-Wook; Kim, Kwan-Ho

    2014-05-01

    Medical linear accelerators (LINAC) for cancer treatment require pulse modulators to generate high-power pulses with a fast rise time, flat top and short duration to drive high-power magnetrons. Solid-state pulse modulators (SSPM) for medical LINACs that use high power semiconductor switches with high repetition rates, high stability and long lifetimes have been introduced to replace conventional linear-type pulse generators that use gaseous discharge switches. In this paper, the performance of a developed SSPM, which mainly consists of a capacitor charger, an insulatedgate bipolar transistor (IGBT)-capacitor stack and a pulse transformer, is evaluated with a dummy load and an X-band magnetron load. A theoretical analysis of the pulse transformer, which is a critical element of the SSPM, is carried out. The output pulse has a fast rise time and low droop, such that the modulator can drive the X-band magnetron.

  5. Surface hardening of VT-22 alloy by inductively coupled plasma nitriding and magnetron deposition of TiN films

    NASA Astrophysics Data System (ADS)

    Kharkov, Maxim M.; Kaziev, Andrey V.; Tumarkin, Alexander V.; Drobinin, Vyacheslav E.; Stepanova, Tatiana V.; Pisarev, Alexander A.

    2017-01-01

    The surface of VT-22 Russian grade titanium alloy samples was modified by inductively coupled plasma (ICP) nitriding followed by magnetron deposition of TiN coatings. Different operating conditions of ICP nitriding and magnetron deposition were considered. The microhardness depth profiles were measured for samples after nitriding. The performance of TiN coatings was examined with a scratch tester.

  6. Surface modification of 316L stainless steel with magnetron sputtered TiN/VN nanoscale multilayers for bio implant applications.

    PubMed

    Subramanian, B; Ananthakumar, R; Kobayashi, Akira; Jayachandran, M

    2012-02-01

    Nanoscale multilayered TiN/VN coatings were developed by reactive dc magnetron sputtering on 316L stainless steel substrates. The coatings showed a polycrystalline cubic structure with (111) preferential growth. XPS analysis indicated the presence of peaks corresponding to Ti2p, V2p, N1s, O1s, and C1s. Raman spectra exhibited the characteristic peaks in the acoustic range of 160-320 cm(-1) and in the optic range between 480 and 695 cm(-1). Columnar structure of the coatings was observed from TEM analysis. The number of adherent platelets on the surface of the TiN/VN multilayer, VN, TiN single layer coating exhibit fewer aggregation and pseudopodium than on substrates. The wear resistance of the multilayer coatings increases obviously as a result of their high hardness. Tafel plots in simulated bodily fluid showed lower corrosion rate for the TiN/VN nanoscale multilayer coatings compared to single layer and bare 316L SS substrate.

  7. Flexible electrochromics: magnetron sputtered tungsten oxide (WO3-x) thin films on Lexan (optically transparent polycarbonate) substrates

    NASA Astrophysics Data System (ADS)

    Uday Kumar, K.; Murali, Dhanya S.; Subrahmanyam, A.

    2015-06-01

    Tungsten oxide (WO3-x) based electrochromics on flexible substrates is a topic of recent interest. The present communication reports the electrochromic properties of WO3-x thin films grown on lexan, an optically transparent polycarbonate thermoplastic substrate. The WO3-x films are prepared at room temperature (300 K) by the reactive DC magnetron sputtering technique. The physical properties of metal oxide thin films are known to be controlled by the oxygen stoichiometry of the film. In the present work, the WO3-x thin films are prepared by varying the oxygen flow rates. All the WO3-x thin films are amorphous in nature. The electrochromic performance of the WO3-x thin films is evaluated by cyclic voltammetry measurements on tin doped indium oxide (ITO) coated lexan and glass substrates. The optical band gap of WO3-x thin films grown on lexan substrates (at any given oxygen flow rate) is significantly higher than those grown on glass substrates. The coloration efficiency of WO3-x thin films (at an oxygen flow rate of 10 sccm) on lexan substrates is: 143.9 cm2 C-1 which is higher compared to that grown on glass: 90.4 cm2 C-1.

  8. Metal-insulator transition of valence-controlled VO2 thin film prepared by RF magnetron sputtering using oxygen radical

    NASA Astrophysics Data System (ADS)

    Suetsugu, Takaaki; Shimazu, Yuichi; Tsuchiya, Takashi; Kobayashi, Masaki; Minohara, Makoto; Sakai, Enju; Horiba, Koji; Kumigashira, Hiroshi; Higuchi, Tohru

    2016-06-01

    We have prepared b-axis-oriented VO2 thin films by RF magnetron sputtering using oxygen radicals as the reactive gas. The VO2 thin films consist of a mixed-valence V3+/V4+ state formed by oxygen vacancies. The V3+ ratio strongly depends on the film thickness and the oxygen partial pressure of the radical gun during deposition. The lattice constant of the b-axis increases and the metal-insulator transition (MIT) temperature decreases with decreasing V3+ ratio, although the VO2 thin films with a high V3+ ratio of 42% do not exhibit MIT. The bandwidths and spectral weights of V 3d a1g and \\text{e}\\text{g}σ bands at around the Fermi level, which correspond to the insulating phase at 300 K, are smaller in the VO2 thin films with a low V3+ ratio. These results indicate that the control of the mixed-valence V3+/V4+ state is important for the MIT of b-axis-oriented VO2 thin films.

  9. Characterization of DC magnetron plasma in Ar/Kr/N2 mixture during deposition of (Cr,Al)N coating

    NASA Astrophysics Data System (ADS)

    Bobzin, K.; Bagcivan, N.; Theiß, S.; Brugnara, R.; Bibinov, N.; Awakowicz, P.

    2017-02-01

    Reactive sputter deposition of (Cr,Al)N coatings in DC magnetron plasmas containing Ar/Kr/N2 mixtures is characterized by applying a combination of voltage–current measurement, optical emission spectroscopy (OES) and numerical simulation. Theoretical and experimental methods supplement each other and their combination permits us to obtain the most reliable information about the processes by physical vapor deposition. Gas temperature (T g) and plasma parameters, namely electron density n e and electron temperature T e are determined by spatial resolved measurements of molecular nitrogen photoemission. Steady-state densities of Cr and Al atoms are measured using OES. The sputtering of Cr and Al atoms is simulated using the TRIDYN code, measured electric current and applied voltage. Transport of sputtered atoms through the plasma volume is simulated by adopting a Monte-Carlo code. In order to quantify the ‘poisoning’ of the target surface with nitrogen, simulated steady state densities of Al and Cr atoms at different states of poisoning and at different distances from the target are compared with the measured densities. In addition, simulated fluxes of Cr and Al atoms to the substrate are compared with the measured deposition rates of the (Cr,Al)N coating.

  10. Electron-Induced Secondary Electron Emission Properties of MgO/Au Composite Thin Film Prepared by Magnetron Sputtering

    NASA Astrophysics Data System (ADS)

    Li, Jie; Hu, Wenbo; Wei, Qiang; Wu, Shengli; Hua, Xing; Zhang, Jintao

    2016-12-01

    As a type of electron-induced secondary electron emitter, MgO/Au composite thin film was prepared by reactive magnetron sputtering of individual Mg target and Au target, and the effects of key process parameters on its surface morphology and secondary electron emission (SEE) properties were investigated. It is found that to deposit a NiO buffer layer on the substrate is conducive to the subsequent growth of MgO grains owing to the lattice matching. The gold addition can raise the electrical conductivity of MgO film and further suppress the surface charging. However, the gold deposition would interfere with the MgO crystallization and increase the surface roughness of MgO/Au film. Therefore, MgO/Au composite thin film with a NiO buffer layer and proper deposition times of MgO and Au can achieve superior SEE properties due to good MgO crystallization, low surface roughness and reasonable electrical conductivity. The optimized MgO/Au composite thin film has a higher SEE coefficient and a lower 1-h SEE degradation rate under electron beam bombardment in comparison with MgO film.

  11. Electron-Induced Secondary Electron Emission Properties of MgO/Au Composite Thin Film Prepared by Magnetron Sputtering

    NASA Astrophysics Data System (ADS)

    Li, Jie; Hu, Wenbo; Wei, Qiang; Wu, Shengli; Hua, Xing; Zhang, Jintao

    2017-03-01

    As a type of electron-induced secondary electron emitter, MgO/Au composite thin film was prepared by reactive magnetron sputtering of individual Mg target and Au target, and the effects of key process parameters on its surface morphology and secondary electron emission (SEE) properties were investigated. It is found that to deposit a NiO buffer layer on the substrate is conducive to the subsequent growth of MgO grains owing to the lattice matching. The gold addition can raise the electrical conductivity of MgO film and further suppress the surface charging. However, the gold deposition would interfere with the MgO crystallization and increase the surface roughness of MgO/Au film. Therefore, MgO/Au composite thin film with a NiO buffer layer and proper deposition times of MgO and Au can achieve superior SEE properties due to good MgO crystallization, low surface roughness and reasonable electrical conductivity. The optimized MgO/Au composite thin film has a higher SEE coefficient and a lower 1-h SEE degradation rate under electron beam bombardment in comparison with MgO film.

  12. Preparation and characterization of self-assembled percolative BaTiO3-CoFe2O4 nanocomposites via magnetron co-sputtering.

    PubMed

    Yang, Qian; Zhang, Wei; Yuan, Meiling; Kang, Limin; Feng, Junxiao; Pan, Wei; Ouyang, Jun

    2014-04-01

    BaTiO3-CoFe2O4 composite films were prepared on (100) SrTiO3 substrates by using a radio-frequency magnetron co-sputtering method at 750 °C. These films contained highly (001)-oriented crystalline phases of perovskite BaTiO3 and spinel CoFe2O4, which can form a self-assembled nanostructure with BaTiO3 well-dispersed into CoFe2O4 under optimized sputtering conditions. A prominent dielectric percolation behavior was observed in the self-assembled nanocomposite. Compared with pure BaTiO3 films sputtered under similar conditions, the nanocomposite film showed higher dielectric constants and lower dielectric losses together with a dramatically suppressed frequency dispersion. This dielectric percolation phenomenon can be explained by the 'micro-capacitor' model, which was supported by measurement results of the electric polarization and leakage current.

  13. Photoluminescence observation from zinc oxide formed by magnetron sputtering at room temperature

    NASA Astrophysics Data System (ADS)

    Kudryashov, D.; Babichev, A.; Nikitina, E.; Gudovskikh, A.; Kladko, P.

    2015-11-01

    The photoluminescence (PL) of ZnO thin films grown by magnetron sputtering at room temperature has been observed. The PL spectra were measured using an instrument from Accent Optical Technologies with a solid state UV laser (λ = 266 nm) as the pumping source and at the temperature of 300 K. Samples grown at sputtering power of 100-200 W show a strong photoluminescence (PL) at wavelength of 377 nm and its intensity shows non-linear dependence with magnetron power. At values of sputtering power less then 100 W PL signal was not observed. A correlation between PL, XRD intensity and ZnO grain size was shown.

  14. On the electron energy in the high power impulse magnetron sputtering discharge

    SciTech Connect

    Gudmundsson, J. T.; Sigurjonsson, P.; Larsson, P.; Lundin, D.; Helmersson, U.

    2009-06-15

    The temporal variation of the electron energy distribution function (EEDF) was measured with a Langmuir probe in a high power impulse magnetron sputtering (HiPIMS) discharge at 3 and 20 mTorr pressures. In the HiPIMS discharge a high power pulse is applied to a planar magnetron giving a high electron density and highly ionized sputtered vapor. The measured EEDF is Maxwellian-like during the pulse; it is broader for lower discharge pressure and it becomes narrower as the pulse progresses. This indicates that the plasma cools as the pulse progresses, probably due to high metal content of the discharge.

  15. Electrical properties of SrTiO3 thin films on Si deposited by magnetron sputtering at low temperature

    NASA Astrophysics Data System (ADS)

    Wang, Zhongchun; Kugler, Veronika; Helmersson, Ulf; Konofaos, N.; Evangelou, E. K.; Nakao, Setsuo; Jin, Ping

    2001-09-01

    Deposition of SrTiO3 (STO) thin films by radio-frequency magnetron sputtering in an ultrahigh vacuum system at a low substrate temperature (˜200 °C) was performed in order to produce high-quality STO/p-Si (100) interfaces and STO insulator layers with dielectric constants of high magnitude. The STO films were identified as polycrystalline by x-ray diffraction, and were approximated with a layered structure according to the best fitting results of raw data from both Rutherford backscattering spectroscopy and variable angle spectroscopic ellipsometry. Room-temperature current-voltage and capacitance-voltage (C-V) measurements on Al/STO/p-Si diodes clearly revealed metal-insulator-semiconductor behavior, and the STO/p-Si interface state densities were of the order of 1011eV-1 cm-2. The dielectric constant of the STO film was 65, and the dielectric loss factor varied between 0.05 and 0.55 for a frequency range of 1 kHz-10 MHz. For a 387 nm thick STO film, the dielectric breakdown field was 0.31 MV cm-1, and the charge storage capacity was 2.1 μC cm-2. These results indicate that STO films are suitable for applications as insulator layers in dynamic random access memories or as cladding layers in electroluminescent devices.

  16. Microstructure and surface properties of chromium-doped diamond-like carbon thin films fabricated by high power pulsed magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Wu, Zhongzhen; Tian, Xiubo; Gui, Gang; Gong, Chunzhi; Yang, Shiqin; Chu, Paul K.

    2013-07-01

    High power pulsed magnetron sputtering (HPPMS) has attracted much interest due to the large plasma density and high ionization rate of sputtered materials. It is expected to produce a highly ionized C flux from a graphite target but unfortunately, the ionization rate of carbon is still very small and the discharge on a solid carbon target is unstable as well. In this work, a stable discharged chromium target is used in the preparation of chromium-doped diamond-like carbon (Cr-DLC) films in HPPMS in reactive C2H2 gas, but the unstable graphite. The chromium concentration in the Cr-DLC films is limited by surface poisoning due to reactive gas. Less than 2% of Cr is incorporated into the DLC films at C2H2 flow rate of 5 sccm or higher. However, as a result of the high ionization rate of the reactive gas in HPPMS, intense ion bombardment of the substrate is realized. The films show a smooth surface and a dense structure with a large sp3 concentration. As the C2H2 flow increase, the sp3 fraction increase and the sp3 to sp2 ratio increase to 0.75 at a C2H2 flow rate of 10 sccm. Compared to the substrate, the Cr-DLC films have lower friction and exhibit excellent corrosion resistance.

  17. Advanced, phase-locked, 100 kW, 1.3 GHz magnetron

    NASA Astrophysics Data System (ADS)

    Read, Michael; Ives, R. Lawrence; Bui, Thuc; Pasquinelli, Ralph; Chase, Brian; Walker, Chris; Conant, Jeff

    2017-03-01

    Calabazas Creek Research, Inc., in collaboration with Fermilab and Communications & Power Industries, LLC, is developing a phase-locked, 100 kW peak, 10 kW average power magnetron-based RF system for driving accelerators. Phase locking will be achieved using an approach originating at Fermilab that includes control of both amplitude and phase on a fast time scale.

  18. Spatial and temporal evolution of ion energies in high power impulse magnetron sputtering plasma discharge

    NASA Astrophysics Data System (ADS)

    Hecimovic, A.; Ehiasarian, A. P.

    2010-09-01

    High power impulse magnetron sputtering (HIPIMS) is a novel deposition technology successfully implemented on full scale industrial machines. HIPIMS utilizes short pulses of high power delivered to the target in order to generate high amount of metal ions. The life-span of ions between the pulses and their energy distribution could strongly influence the properties and characteristics of the deposited coating. In modern industrial coating machines the sample rotates on a substrate holder and changes its position and distance with regard to the magnetron. Time resolved measurements of the ion energy distribution function (IEDF) at different distances from the magnetron have been performed to investigate the temporal evolution of ions at various distances from target. The measurements were performed using two pressures, 1 and 3 Pa to investigate the influence of working gas pressure on IEDF. Plasma sampling energy-resolved mass spectroscopy was used to measure the IEDF of Ti1+, Ti2+, Ar1+, and Ar2+ ions in HIPIMS plasma discharge with titanium (Ti) target in Ar atmosphere. The measurements were done over a full pulse period and the distance between the magnetron and the orifice of the mass spectrometer was changed from 25 to 215 mm.

  19. Structure of the metallic films deposited on small spheres trapped in the rf magnetron plasma

    NASA Astrophysics Data System (ADS)

    Filippov, A. V.; Pal, A. F.; Ryabinkin, A. N.; Serov, A. O.

    2016-11-01

    Metallic coatings were deposited onto glass spheres having diameters from several to one hundred micrometers by the magnetron sputtering. Two different experimental schemes were exploited. One of them had the traditional configuration where a magnetron sputter was placed at one hundred millimeters from particles. In this scheme, continuous mechanical agitation in a fluidized bed was used to achieve uniformity of coatings. In the second scheme the treated particles (substrates) levitated in a magnetron rf plasma over a sputtered rf electrode (target) at the distance d of few mm from it and at gas pressure p values of 30-100 mTorr. These parameters are essentially different from those in the traditional sputtering. Agitation due to the features of a particle confinement in dusty plasma was used here to obtain uniform coatings. Thickness and morphology of the obtained coatings were studied. As it is known, film growth rate and structure are determined by the substrate temperature, the densities of ion and neutral atom fluxes to the substrate surface, the radiation flux density, and the heat energy produced due to the surface condensation of atoms and recombination of electrons and ions. These parameters particularly depend on the product of p and d. In the case of magnetron rf dusty plasma, it is possible to achieve the pd value several times lower than the lowest value proper to the first traditional case. Completely different dependencies of the film growth rate and structure on the pd value in these sputtering processes were observed and qualitatively explained.

  20. Low-pressure planar magnetron discharge for surface deposition and nanofabrication

    SciTech Connect

    Baranov, Oleg; Romanov, Maxim; Wolter, Matthias; Kumar, Shailesh; Zhong Xiaoxia; Ostrikov, Kostya

    2010-05-15

    Current-voltage characteristics of the planar magnetron are studied experimentally and by numerical simulation. Based on the measured current-voltage characteristics, a model of the planar magnetron discharge is developed with the background gas pressure and magnetic field used as parameters. The discharge pressure was varied in a range of 0.7-1.7 Pa, the magnetic field of the magnetron was of 0.033-0.12 T near the cathode surface, the discharge current was from 1 to 25 A, and the magnetic field lines were tangential to the substrate surface in the region of the magnetron discharge ignition. The discharge model describes the motion of energetic secondary electrons that gain energy by passing the cathode sheath across the magnetic field, and the power required to sustain the plasma generation in the bulk. The plasma electrons, in turn, are accelerated in the electric field and ionize effectively the background gas species. The model is based on the assumption about the prevailing Bohm mechanism of electron conductivity across the magnetic field. A criterion of the self-sustained discharge ignition is used to establish the dependence of the discharge voltage on the discharge current. The dependence of the background gas density on the current is also observed from the experiment. The model is consistent with the experimental results.

  1. Magnetron deposited TiN coatings for protection of Al-Cu-Ag-Mg-Mn alloy

    NASA Astrophysics Data System (ADS)

    Stepanova, Tatiana V.; Kaziev, Andrey V.; Atamanov, Mikhail V.; Tumarkin, Alexander V.; Dolzhikova, Svetlana A.; Izmailova, Nelly Ph; Kharkov, Maxim M.; Berdnikova, Maria M.; Mozgrin, Dmitry V.; Pisarev, Alexander A.

    2016-09-01

    TiN coatings were deposited on a new Al super-alloy by magnetron sputtering in argon/nitrogen environment. The deposited layer structure, microhardness, adhesion, corrosion resistance, and fatigue life were investigated and tests demonstrated improved performance of the alloy.

  2. A high power impulse magnetron sputtering model to explain high deposition rate magnetic field configurations

    NASA Astrophysics Data System (ADS)

    Raman, Priya; Weberski, Justin; Cheng, Matthew; Shchelkanov, Ivan; Ruzic, David N.

    2016-10-01

    High Power Impulse Magnetron Sputtering (HiPIMS) is one of the recent developments in the field of magnetron sputtering technology that is capable of producing high performance, high quality thin films. Commercial implementation of HiPIMS technology has been a huge challenge due to its lower deposition rates compared to direct current Magnetron Sputtering. The cylindrically symmetric "TriPack" magnet pack for a 10 cm sputter magnetron that was developed at the Center for Plasma Material Interactions was able to produce higher deposition rates in HiPIMS compared to conventional pack HiPIMS for the same average power. The "TriPack" magnet pack in HiPIMS produces superior substrate uniformity without the need of substrate rotation in addition to producing higher metal ion fraction to the substrate when compared to the conventional pack HiPIMS [Raman et al., Surf. Coat. Technol. 293, 10 (2016)]. The films that are deposited using the "TriPack" magnet pack have much smaller grains compared to conventional pack DC and HiPIMS films. In this paper, the reasons behind the observed increase in HiPIMS deposition rates from the TriPack magnet pack along with a modified particle flux model is discussed.

  3. A cookbook for building a high-current dimpled H– magnetron source for accelerators

    DOE PAGES

    Bollinger, Daniel S.; Karns, Patrick R.; Tan, Cheng -Yang

    2015-10-30

    A high-current (>50 mA) dimpled H– magnetron source has been built at Fermilab for supplying H– beam to the entire accelerator complex. Despite many decades of expertise with slit H– magnetron sources at Fermilab, we were faced with many challenges from the dimpled H– magnetron source, which needed to be overcome in order to make it operational. Dimpled H– sources for high-energy physics are not new: Brookhaven National Laboratory has operated a dimpled H- source for more than two decades. However, the transference of that experience to Fermilab took about two years because a cookbook for building this type ofmore » source did not exist and seemingly innocuous or undocumented choices had a huge impact on the success or failure for this type of source. Moreover, it is the goal of this paper to document the reasons for these choices and to present a cookbook for building and operating dimpled H– magnetron sources.« less

  4. Flow of nanosize cluster-containing plasma in a magnetron discharge

    SciTech Connect

    Smirnov, Boris M.

    2007-06-15

    A magnetron source of silver clusters captured by an argon flow with the quadrupole mass filter is used for the analysis of charged clusters after an orifice of the magnetron chamber, and the size distribution function follows from the analysis of clusters deposited on a silicon substrate by an atomic force microscope. Cluster charge near an orifice results from attachment of ions of a secondary plasma that is a tail of a magnetron plasma, and the cluster charge is mostly positive. The character of passage of a buffer gas flow with metal clusters through an orifice is studied both theoretically and experimentally. Assuming the cone shape of the drift chamber near the orifice, we analyze drift of charged clusters in a buffer gas flow towards the orifice if the electric field inside the drift chamber is created by charged rings on the cone surface. Under experimental conditions, when an equilibrium between the buffer gas flow and cluster flux is violated, a typical voltage of rings and parameters of corona discharge for cluster charging are estimated if the electric field does not allow for clusters to reach walls of the drift chamber. The number density of clusters near the orifice is estimated that increases both due to violation of an equilibrium for the cluster flux inside the buffer gas flow and owing to focusing of the cluster by the electric field that is created by electrodes located near walls and due to diffusion motion of clusters. Processes of cluster charging in the magnetron chamber are analyzed.

  5. Flow of nanosize cluster-containing plasma in a magnetron discharge.

    PubMed

    Smirnov, Boris M; Shyjumon, Ibrahimkutty; Hippler, Rainer

    2007-06-01

    A magnetron source of silver clusters captured by an argon flow with the quadrupole mass filter is used for the analysis of charged clusters after an orifice of the magnetron chamber, and the size distribution function follows from the analysis of clusters deposited on a silicon substrate by an atomic force microscope. Cluster charge near an orifice results from attachment of ions of a secondary plasma that is a tail of a magnetron plasma, and the cluster charge is mostly positive. The character of passage of a buffer gas flow with metal clusters through an orifice is studied both theoretically and experimentally. Assuming the cone shape of the drift chamber near the orifice, we analyze drift of charged clusters in a buffer gas flow towards the orifice if the electric field inside the drift chamber is created by charged rings on the cone surface. Under experimental conditions, when an equilibrium between the buffer gas flow and cluster flux is violated, a typical voltage of rings and parameters of corona discharge for cluster charging are estimated if the electric field does not allow for clusters to reach walls of the drift chamber. The number density of clusters near the orifice is estimated that increases both due to violation of an equilibrium for the cluster flux inside the buffer gas flow and owing to focusing of the cluster by the electric field that is created by electrodes located near walls and due to diffusion motion of clusters. Processes of cluster charging in the magnetron chamber are analyzed.

  6. System for reactivating catalysts

    SciTech Connect

    Ginosar, Daniel M.; Thompson, David N.; Anderson, Raymond P.

    2010-03-02

    A method of reactivating a catalyst, such as a solid catalyst or a liquid catalyst is provided. The method comprises providing a catalyst that is at least partially deactivated by fouling agents. The catalyst is contacted with a fluid reactivating agent that is at or above a critical point of the fluid reactivating agent and is of sufficient density to dissolve impurities. The fluid reactivating agent reacts with at least one fouling agent, releasing the at least one fouling agent from the catalyst. The at least one fouling agent becomes dissolved in the fluid reactivating agent and is subsequently separated or removed from the fluid reactivating agent so that the fluid reactivating agent may be reused. A system for reactivating a catalyst is also disclosed.

  7. Multi-functional reactively-sputtered copper oxide electrodes for supercapacitor and electro-catalyst in direct methanol fuel cell applications

    NASA Astrophysics Data System (ADS)

    Pawar, Sambhaji M.; Kim, Jongmin; Inamdar, Akbar I.; Woo, Hyeonseok; Jo, Yongcheol; Pawar, Bharati S.; Cho, Sangeun; Kim, Hyungsang; Im, Hyunsik

    2016-02-01

    This work reports on the concurrent electrochemical energy storage and conversion characteristics of granular copper oxide electrode films prepared using reactive radio-frequency magnetron sputtering at room temperature under different oxygen environments. The obtained films are characterized in terms of their structural, morphological, and compositional properties. X-ray diffraction, X-ray photoelectron spectroscopy and scanning electron microscope studies reveal that granular, single-phase Cu2O and CuO can be obtained by controlling the oxygen flow rate. The electrochemical energy storage properties of the films are investigated by carrying out cyclic voltammetry, galvanostatic charge/discharge and electrochemical impedance spectroscopy tests. The electrochemical analysis reveals that the Cu2O and CuO electrodes have high specific capacitances of 215 and 272 F/g in 6 M KOH solution with a capacity retention of about 80% and 85% after 3000 cycles, respectively. Cyclic voltammetry and chronoamperometry are used to study the electrochemical energy conversion properties of the films via methanol electro-oxidation. The results show that the Cu2O and CuO electrodes are electro-catalytically active and highly stable.

  8. Effect of substrate roughness and working pressure on photocatalyst of N-doped TiOx films prepared by reactive sputtering with air

    NASA Astrophysics Data System (ADS)

    Lee, Seon-Hong; Yamasue, Eiji; Okumura, Hideyuki; Ishihara, Keiichi N.

    2015-01-01

    N-doped TiOx films on the glass substrate were prepared by radio-frequency (RF) magnetron reactive sputtering of Ti target in a mixed gas of argon and dry air. The effect of substrate roughness and working pressure on the physical properties and the photocatalytic properties of the N-doped TiOx films was investigated. The surface roughness of glass substrate has little influence on the film properties such as produced phases, lattice parameters, introduced nitrogen contents, and atomic bonding configurations, but significant influence on the surface roughness of film resulting in the variation of the photocatalytic ability. The working pressure has little influence on the produced phases and the atomic bonding configurations, but significant influence on the atomic concentration of the N-doped TiOx film, resulting in the large variation of optical, structural, and photocatalytic properties. It is suggested that the high photocatalysis of N-doped TiOx film requires a certain range of the N doping concentration which shows the interstitial complex N doping states in TiO2.

  9. Multi-functional reactively-sputtered copper oxide electrodes for supercapacitor and electro-catalyst in direct methanol fuel cell applications

    PubMed Central

    Pawar, Sambhaji M.; Kim, Jongmin; Inamdar, Akbar I.; Woo, Hyeonseok; Jo, Yongcheol; Pawar, Bharati S.; Cho, Sangeun; Kim, Hyungsang; Im, Hyunsik

    2016-01-01

    This work reports on the concurrent electrochemical energy storage and conversion characteristics of granular copper oxide electrode films prepared using reactive radio-frequency magnetron sputtering at room temperature under different oxygen environments. The obtained films are characterized in terms of their structural, morphological, and compositional properties. X-ray diffraction, X-ray photoelectron spectroscopy and scanning electron microscope studies reveal that granular, single-phase Cu2O and CuO can be obtained by controlling the oxygen flow rate. The electrochemical energy storage properties of the films are investigated by carrying out cyclic voltammetry, galvanostatic charge/discharge and electrochemical impedance spectroscopy tests. The electrochemical analysis reveals that the Cu2O and CuO electrodes have high specific capacitances of 215 and 272 F/g in 6 M KOH solution with a capacity retention of about 80% and 85% after 3000 cycles, respectively. Cyclic voltammetry and chronoamperometry are used to study the electrochemical energy conversion properties of the films via methanol electro-oxidation. The results show that the Cu2O and CuO electrodes are electro-catalytically active and highly stable. PMID:26888077

  10. Hydroxyapatite coating on biodegradable AZ31 and Mg-Ca alloys prepared by RF-magnetron sputtering

    SciTech Connect

    Mukhametkaliyev, T. Surmeneva, M. Surmenev, R.; Mathan, B. K.

    2015-11-17

    A thin film of hydroxyapatite (HA) was deposited on AZ31 and Mg-Ca alloys by using radio frequency (RF) magnetron sputtering. The thickness of the HA coating was determined to be 750 nm. The phase composition, microstructure, and surface morphology of the HA coatings were investigated using X-ray diffraction and scanning electron microscopy. In vitro degradation behaviour of the HA coated alloys was evaluated in simulated body fluid (SBF) and 3.5wt.% NaCl solution using electrochemical method. The coatings homogeneously covered the entire surface of the substrates. The coating structure corresponded to a nanostructured HA. The ultrathin coating significantly improved the degradation resistance of the alloy. Nanocrystalline HA coating significantly improved the corrosion resistance of the Mg-Ca and AZ31 magnesium alloys. The polarization resistance (Rp) of the coated Mg-Ca alloy was more than two-order of magnitude higher and the corrosion current density I{sub corr} reduced by ∼ 98% as compared to the base alloy.

  11. Electrochemical characterization of silicon/graphene/MWCNT hybrid lithium-ion battery anodes produced via RF magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Toçoǧlu, Ubeyd; Hatipoǧlu, Gizem; Alaf, Miraç; Kayış, Fuat; Akbulut, Hatem

    2016-12-01

    In this study it was aimed to enhance cycling performance of silicon lithium ion battery anodes via producing flexible Silicon/Graphene/MWCNT composite structures. The volumetric expansions, which are the primary obstacle that hinders the practical usage of silicon anodes, were tried to suppress using flexible graphene/MWCNT paper substrates. Moreover to achieve lightweight and high electrical conductive anodes, the advantage of graphene was aimed to be exploited. Silicon/graphene/MWCNT flexible composite anodes were produced via radio frequency (RF) magnetron sputtering technique. Graphene/MWCNT papers were produced with vacuum filtration technique as substrate for sputtering process. At coating process of papers constant sputtering power was applied. Phase analysis was conducted with X-ray diffraction (XRD) technique and Raman spectroscopy. Field emission scanning electron microscopy (FESEM). Cyclic voltammetry (CV) tests were carried out to reveal reversible reactions between silicon and lithium. Galvanostatic charge/discharge technique was employed to determine the cyclic performance of anodes. Electrochemical impedance spectroscopy technique was used to understand the relation between cyclic performance and internal resistance of cells. Results showed that improvement on cyclic performance of silicon anodes was achieved with novel composite silicon/graphene/MWCNT composite anode structures.

  12. Surface and optical properties of indium tin oxide layer deposition by RF magnetron sputtering in argon atmosphere

    NASA Astrophysics Data System (ADS)

    Yudar, H. Hakan; Korkmaz, Şadan; Özen, Soner; Şenay, Volkan; Pat, Suat

    2016-08-01

    This study focused on the characterization and properties of transparent and conductive indium tin oxide (ITO) thin films deposited in argon atmosphere. ITO thin films were coated onto glass substrates by radio frequency (RF) magnetron sputtering technique at 75 and 100 W RF powers. Structural characteristics of producing films were investigated through X-ray diffraction analysis. UV-Vis spectrophotometer and interferometer were used to determine transmittance, absorbance and reflectance values of samples. The surface morphology of the films was characterized by atomic force microscope. The calculated band gaps were 3.8 and 4.1 eV for the films at 75 and 100 W, respectively. The effect of RF power on crystallinity of prepared films was explored using mentioned analysis methods. The high RF power caused higher poly crystallinity in the produced samples. The thickness and refractive index values for all samples increased respect to an increment of RF power and were calculated as 20, 50 nm and 1.71, 1.86 for samples at 75 and 100 W, respectively. Finally, the estimated grain sizes for all prepared films decreased with increasing of 2 θ degrees, and the number of crystallite per unit volume was calculated. It was found that nearly all properties including sheet resistance and resistivity depend on the RF power.

  13. Effects of various deposition times and RF powers on CdTe thin film growth using magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Ghorannevis, Z.; Akbarnejad, E.; Ghoranneviss, M.

    2016-09-01

    Cadmium telluride (CdTe) is a p-type II-VI compound semiconductor, which is an active component for producing photovoltaic solar cells in the form of thin films, due to its desirable physical properties. In this study, CdTe film was deposited using the radio frequency (RF) magnetron sputtering system onto a glass substrate. To improve the properties of the CdTe film, effects of two experimental parameters of deposition time and RF power were investigated on the physical properties of the CdTe films. X-ray Diffraction (XRD), atomic force microscopy (AFM) and spectrophotometer were used to study the structural, morphological and optical properties of the CdTe samples grown at different experimental conditions, respectively. Our results suggest that film properties strongly depend on the experimental parameters and by optimizing these parameters, it is possible to tune the desired structural, morphological and optical properties. From XRD data, it is found that increasing the deposition time and RF power leads to increasing the crystallinity as well as the crystal sizes of the grown film, and all the films represent zinc blende cubic structure. Roughness values given from AFM images suggest increasing the roughness of the CdTe films by increasing the RF power and deposition times. Finally, optical investigations reveal increasing the film band gaps by increasing the RF power and the deposition time.

  14. Photocatalytic hydroxyapatite/titanium dioxide multilayer thin film deposited onto glass using an rf magnetron sputtering technique

    NASA Astrophysics Data System (ADS)

    Ozeki, K.; Janurudin, Juliana M.; Aoki, H.; Fukui, Y.

    2007-01-01

    Hydroxyapatite (HA)/titanium dioxide (TiO 2) thin film was deposited on glass using a radio frequency magnetron sputtering. X-ray diffraction (XRD), Fourier-transform infrared spectrometry, ultraviolet-visible spectroscopy and measurement of its photocatalytic activity by the decomposition of formaldehyde gas and the bacterial survival test of Escherichia coli ( E. coli) cells were applied to characterize the film. After heat treatment (at 500 °C), XRD analysis of the HA/TiO 2 film showed a crystalline TiO 2 crystal structure with anatase phase. The transmittance of the HA/TiO 2 film decreased after the heat treatment, however, the average transmittance remained at 87% in the visible light range. In the decomposition of formaldehyde gas, the HA/TiO 2 film showed a higher decomposition rate than either the TiO 2 or the HA film alone. However, in the bacterial survival test, survival of cells on the HA/TiO 2 film was higher than that on the TiO 2 film, which indicates the HA/TiO 2 film has a lower bactericidal effect than the TiO 2 film alone.

  15. Influence of oxygen flow rate on metal-insulator transition of vanadium oxide thin films grown by RF magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Ma, Xu; Liu, Xinkun; Li, Haizhu; Zhang, Angran; Huang, Mingju

    2017-03-01

    High-quality vanadium oxide ( VO2) films have been fabricated on Si (111) substrates by radio frequency (RF) magnetron sputtering deposition method. The sheet resistance of VO2 has a significant change (close to 5 orders of magnitude) in the process of the metal-insulator phase transition (MIT). The field emission-scanning electron microscope (FE-SEM) results show the grain size of VO2 thin films is larger with the increase of oxygen flow. The X-ray diffraction (XRD) results indicate the thin films fabricated at different oxygen flow rates grow along the (011) crystalline orientation. As the oxygen flow rate increases from 3 sccm to 6 sccm, the phase transition temperature of the films reduces from 341 to 320 K, the width of the thermal hysteresis loop decreases from 32 to 9 K. The thin films fabricated in the condition of 5 sccm have a high temperature coefficient of resistance (TCR) -3.455%/K with a small resistivity of 2.795 ρ/Ω cm.

  16. Effects of discharge power on the structural and optical properties of TGZO thin films prepared by RF magnetron sputtering technique

    NASA Astrophysics Data System (ADS)

    Gu, Jin-hua; Lu, Zhou; Zhong, Zhi-you; Long, Lu; Long, Hao

    2016-05-01

    The transparent semiconductors of Ti and Ga-incorporated ZnO (TGZO) thin films were prepared by radio frequency (RF) magnetron sputtering onto glass substrates. The effects of discharge power on the physical properties of thin films are studied. Experimental results show that all nanocrystalline TGZO thin films possess preferential orientation along the (002) plane. The discharge power significantly affects the crystal structure and optical properties of thin films. When the discharge power is 200 W, the TGZO thin film has the optimal crystalline quality and optical properties, with the narrowest full width at half-maximum ( FWHM) of 1.76×10-3 rad, the largest average grain size of 82.4 nm and the highest average transmittance of 84.3% in the visible range. The optical gaps of thin films are estimated by the Tauc's relation and observed to increase firstly and then decrease with the increase of the discharge power. In addition, the optical parameters, including refractive index, extinction coefficient, dielectric function and dissipation factor of the thin films, are determined by optical characterization methods. The dispersion behavior of the refractive index is also analyzed using the Sellmeier's dispersion model.

  17. Simulation of nanoindentation experiment on RF magnetron sputtered nanocolumnar V2O5 film using finite element method

    NASA Astrophysics Data System (ADS)

    Porwal, Deeksha; Gupta, A. K.; Pillai, Anju M.; Sharma, Anand Kumar; Mukhopadhyay, Anoop Kumar; Khan, Kallol; Dey, Arjun

    2016-07-01

    The present work reports the nanomechanical behavior of a pulsed radio frequency (RF) magnetron sputtered vanadium pentoxide (V2O5) film deposited on silicon (Si) substrate using a combination of nanoindentation experiments and a finite element model (FEM). Deposited V2O5 film is characterized by x-ray diffraction (XRD), nanoprofilometry, field emission scanning electron microscopy (FESEM), nanoindentation and FEM. The phase pure 6.16 μm V2O5 film shows a nanocolumnar structure. The film exhibits nanohardness (H) of 0.16 ± 0.013 GPa and Young’s modulus (E) of about 12.05 ± 1.41 GPa. The FEM reproduces experimentally obtained load versus depth (P-h) plot and subsequently give yield stress and strain hardening component data of V2O5 film on Si substrate. Stress-strain behavior and von-Mises stress distribution of the V2O5 film with Si substrate system are also simulated. The FE model confirms the local maximum equivalent stress active underneath the nanoindenters to be nearly twice as high as the yield stress and thereby explains the plastic deformation observed in the V2O5 film.

  18. Effect of thickness on surface morphology, optical and humidity sensing properties of RF magnetron sputtered CCTO thin films

    NASA Astrophysics Data System (ADS)

    Ahmadipour, Mohsen; Ain, Mohd Fadzil; Ahmad, Zainal Arifin

    2016-11-01

    In this study, calcium copper titanate (CCTO) thin films were deposited on ITO substrates successfully by radio frequency (RF) magnetron sputtering method in argon atmosphere. The CCTO thin films present a polycrystalline, uniform and porous structure. The surface morphology, optical and humidity sensing properties of the synthesized CCTO thin films have been studied by X-ray diffraction (XRD), atomic force microscopy (AFM), field emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectroscopy (EDX), UV-vis spectrophotometer and current-voltage (I-V) analysis. XRD and AFM confirmed that the intensity of peaks and pore size of CCTO thin films were enhanced by increasing the thin films. Tauc plot method was adopted to estimate the optical band gaps. The surface structure and energy band gaps of the deposited films were affected by film thickness. Energy band gap of the layers were 3.76 eV, 3.68 eV and 3.5 eV for 200 nm, 400 nm, and 600 nm CCTO thin films layer, respectively. The humidity sensing properties were measured by using direct current (DC) analysis method. The response times were 12 s, 22 s, and 35 s while the recovery times were 500 s, 600 s, and 650 s for 200 nm, 400 nm, and 600 nm CCTO thin films, respectively at humidity range of 30-90% relative humidity (RH).

  19. Investigation of the properties of BiFeO3/intermediate-layer structures fabricated by magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Kamzin, A. S.; Kamzina, L. S.; Chang, H. W.; Yu, Y. C.; Tu, S. Y.

    2015-09-01

    The properties of BiFeO3/intermediate layer/substrate structures fabricated by radio-frequency magnetron sputtering at low temperatures (450°C) and by deposition on substrates and intermediate layers between the substrate and the BiFeO3 film have been investigated. In the structures, glass substrates or commercial Pt/Ti/SiO2/Si(001) substrates have been used, and intermediate layers have been prepared from L10 FePt or Pt films. Intermediate layers of Pt and L10 FePt have the (111) and (001) textures, respectively, induced by rapid thermal annealing. It has been revealed that the deposition on the commercial substrates leads to the formation of BiFeO3 isotropic films that have a large surface roughness and consist of grains ˜200 nm in size with the BiFeO3 perovskite structure. In the case of the deposition of a BiFeO3 film on a Pt(111) intermediate layer, the BiFeO3 phase is suppressed. The deposition on an intermediate layer of the L10 FePt film with the (001) texture results in the formation of a single-phase BiFeO3 film with the (001) texture and the perovskite structure, which (as compared to the BiFeO3 films grown on the commercial substrate) has a less pronounced roughness, smaller grain sizes, and significantly better ferroelectric properties.

  20. Raman and Optoelectronic Properties of Zn1-xMgxO Thin Films Prepared by RF Magnetron Sputtering

    NASA Astrophysics Data System (ADS)

    Huang, Q. L.; Fang, L.; Ruan, H. B.; Guo, B. D.; Wu, F.; Kong, C. Y.

    A series of Zn1-xMgxO (x = 0 ~ 0.16) films have been prepared on glass substrates by RF magnetron sputtering. The structure, surface morphology, composition, optical and electrical properties of the films were investigated by X-ray diffraction (XRD), scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDX), Raman spectroscopy, UV-Vis spectrophotometer and Hall measurement, respectively. It reveals that the obtained films are uniform hexagonal wurtzite polycrystalline with grain size about 100 nm.The optical transmittance are over 80% and the band gap (Eg) has linear relationship with Mg content: Eg = 1.67x + 3.274 (eV) (0 < x < 0.16). The resistivity of the films increases with the increase of Mg content. The Raman spectra of the films show that the position of E2 peaks (473 cm-1) has not changed, but the A1(LO) mode (577 cm-1) frequency shifts to lower wavenumbers with the increase of Mg content, indicating that Mg-doping does not cause intensive lattice deformation, but results in the decrease of the carrier concentration, which is corresponding to the degradation of the conductivity of ZnMgO films with the increase of Mg content.

  1. Determination of the number density of excited and ground Zn atoms during rf magnetron sputtering of ZnO target

    SciTech Connect

    Maaloul, L.; Gangwar, R. K.; Stafford, L.

    2015-07-15

    A combination of optical absorption spectroscopy (OAS) and optical emission spectroscopy measurements was used to monitor the number density of Zn atoms in excited 4s4p ({sup 3}P{sub 2} and {sup 3}P{sub 0}) metastable states as well as in ground 4s{sup 2} ({sup 1}S{sub 0}) state in a 5 mTorr Ar radio-frequency (RF) magnetron sputtering plasma used for the deposition of ZnO-based thin films. OAS measurements revealed an increase by about one order of magnitude of Zn {sup 3}P{sub 2} and {sup 3}P{sub 0} metastable atoms by varying the self-bias voltage on the ZnO target from −115 to −300 V. Over the whole range of experimental conditions investigated, the triplet-to-singlet metastable density ratio was 5 ± 1, which matches the statistical weight ratio of these states in Boltzmann equilibrium. Construction of a Boltzmann plot using all Zn I emission lines in the 200–500 nm revealed a constant excitation temperature of 0.33 ± 0.04 eV. In combination with measured populations of Zn {sup 3}P{sub 2} and {sup 3}P{sub 0} metastable atoms, this temperature was used to extrapolate the absolute number density of ground state Zn atoms. The results were found to be in excellent agreement with those obtained previously by actinometry on Zn atoms using Ar as the actinometer gas [L. Maaloul and L. Stafford, J. Vac. Sci. Technol., A 31, 061306 (2013)]. This set of data was then correlated to spectroscopic ellipsometry measurements of the deposition rate of Zn atoms on a Si substrate positioned at 12 cm away from the ZnO target. The deposition rate scaled linearly with the number density of Zn atoms. In sharp contrast with previous studies on RF magnetron sputtering of Cu targets, these findings indicate that metastable atoms play a negligible role on the plasma deposition dynamics of Zn-based coatings.

  2. Low substrate temperature fabrication of high-performance metal oxide thin-film by magnetron sputtering with target self-heating

    SciTech Connect

    Yang, W. F.; Liu, Z. G.; Wu, Z. Y.; Hong, M. H.; Wang, C. F.; Lee, Alex Y. S.; Gong, H.

    2013-03-18

    Al-doped ZnO (AZO) films with high transmittance and low resistivity were achieved on low temperature substrates by radio frequency magnetron sputtering using a high temperature target. By investigating the effect of target temperature (T{sub G}) on electrical and optical properties, the origin of electrical conduction is verified as the effect of the high T{sub G}, which enhances crystal quality that provides higher mobility of electrons as well as more effective activation for the Al dopants. The optical bandgap increases from 3.30 eV for insulating ZnO to 3.77 eV for conducting AZO grown at high T{sub G}, and is associated with conduction-band filling up to 1.13 eV due to the Burstein-Moss effect.

  3. Measurement of deposition rate and ion energy distribution in a pulsed dc magnetron sputtering system using a retarding field analyzer with embedded quartz crystal microbalance.

    PubMed

    Sharma, Shailesh; Gahan, David; Scullin, Paul; Doyle, James; Lennon, Jj; Vijayaraghavan, Rajani K; Daniels, Stephen; Hopkins, M B

    2016-04-01

    A compact retarding field analyzer with embedded quartz crystal microbalance has been developed to measure deposition rate, ionized flux fraction, and ion energy distribution arriving at the substrate location. The sensor can be placed on grounded, electrically floating, or radio frequency (rf) biased electrodes. A calibration method is presented to compensate for temperature effects in the quartz crystal. The metal deposition rate, metal ionization fraction, and energy distribution of the ions arriving at the substrate location are investigated in an asymmetric bipolar pulsed dc magnetron sputtering reactor under grounded, floating, and rf biased conditions. The diagnostic presented in this research work does not suffer from complications caused by water cooling arrangements to maintain constant temperature and is an attractive technique for characterizing a thin film deposition system.

  4. Investigation of the biaxial stress of Al-doped ZnO thin films on a flexible substrate with RF magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Huang, Kuo-Ting; Chen, Hsi-Chao; Cheng, Po-Wei; Chang, Jhe-Ming

    2016-01-01

    Transparent conductive Al-doped ZnO (AZO) thin films were deposited onto poly(ethylene terephthalate) (PET) substrate, using the radio frequency (RF) magnetron sputtering method. The residual stress of flexible electronics was investigated by a double beam shadow moiré interferometer with phase shifting interferometry (PSI). Moreover, the biaxial stress of AZO thin films can be graphically represented by using Mohr’s circle of stress. The residual stress of AZO thin films becomes more compressive with the increase in sputtering power. The maximum residual stress is -1115.74 MPa, and the shearing stress is 490.57 MPa at a sputtering power of 200 W. The trends of residual stress were evidenced by the X-ray diffraction (XRD) patterns and optical properties of AZO thin films. According to the evaluation results of the refractive index and the extinction coefficient, the AZO thin films have better quality when the sputtering power less than 100 W.

  5. Development of a highly transparent, low-resistance lithium-doped nickel oxide triple-layer film deposited by magnetron sputtering.

    PubMed

    Wu, Chia-Ching; Shih, Wei-Chen

    2017-01-31

    This research presents a triple-layer transparent conductive oxide thin film, with a lithium-doped nickel oxide/silver/lithium-doped nickel oxide (L-NiO/Ag/L-NiO) structure using radio-frequency (RF) magnetron sputtering on glass substrates. The high transmittance L-NiO thin films were deposited using the sputtering method with Ar/H2 as the reaction gases. The triple-layer structure, L-NiO/Ag/L-NiO, showed impressive electrical conductivity. The figure of merit (FOM) results indicated that the L-NiO/Ag/L-NiO triple-layer thin films with Ag deposition times of 2 min possessed satisfactory optical and electrical properties for potential applications.

  6. A new generation of CMOS-compatible high frequency micro-inductors with ferromagnetic cores: Theory, fabrication and characterisation

    NASA Astrophysics Data System (ADS)

    Seemann, K.; Leiste, H.; Bekker, V.

    2006-07-01

    A new generation of CMOS-compatible micro-inductor prototypes with magnetic cores were realized, characterised as well as theoretically modelled in a frequency range up to 4 GHz, a frequency range where, e.g., mobile communication and global positioning systems (GPS) are operated. The micro-inductor's electrical magnitudes like inductance ( L) and quality factor ( Q) were theoretically described by means of an equivalent circuit model taking the frequency behaviour of the magnetic film core, expressed by the Landau-Lifschitz and Maxwell equations, into account. Six inch targets were used to deposit metallic layers (Al 99Si 0.5Cu 0.5), diffusion barriers (Si 3N 4), insulating layers (SiO 2) and magnetic films (Fe 39Co 30Ta 8N 23) by DC or reactive r.-f.-magnetron sputtering. All film materials were patterned by NUV-lithography (Near Ultra Violet), plasma beam milling and reactive ion etching to form the micro-inductors on 4-inch silicon wafers. The inductor windings are arranged in a way that they possess a low resistance and generate a quasi closed flux at the end of the cores to minimise eddy current losses in the silicon substrate. In order to diminish demagnetising effects in an efficient working core the magnetic films were patterned into micro squares with lateral dimensions of 20 and 100 μm with 100 nm in thickness. More magnetic volume and a higher micro-inductor cross-section was achieved by producing 100 nm magnetic double layers separated by a 800 nm thick Si 3N 4 inter-layer. To guarantee a sufficiently high cut-off frequency of the magnetic films, they were annealed in a static magnetic field at a temperature of 400 °C for uniaxial anisotropy induction. This represents a temperature treatment where aluminium CMOS processes take place. As a result of patterning, the magnetic film material exhibited a remarkable increase of the cut-off frequency from 2 GHz in laterally extended films up to 3.2 GHz which could be also observed in the measured frequency

  7. Thermochromic VO2 thin films deposited by magnetron sputtering for smart window applications

    NASA Astrophysics Data System (ADS)

    Fortier, Jean-Philippe

    objectives in mind. To start, we had to find a first recipe to obtain our first samples of the material. Using the literature as a starting point, several samples were deposited by magnetron sputtering while improving certain deposition conditions as well as varying influential deposition parameters. Once the oxide obtained, it was necessary to optimize the parameters not only to render thermochromic coatings with the highest possible quality, but also to determine each parameter's sensitivity. Characterization techniques such as microscopy, spectroscopy, ellipsometry, scanning electron microscopy, atomic force microscopy, Raman spectroscopy, x-ray diffraction and finally, time-of-flight secondary ion mass spectrometry were used to analyze different aspects of our multiple samples. Indeed, to mention only the ix most relevant observations, we were able to confirm that the microstructure, composition, most relevant observations, we were able to confirm that the microstructure, composition, crystallinity and film thickness have a significant impact on the coating's thermochromic behavior as well as on its optical properties. As a result, the oxygen concentration and the thickness had to be optimized and the deposition temperature, maximized. Reactive poisoning of the sputtering target is also a phenomenon that needs to be considered during deposition. Then, our sputtering target and substrate cleaning procedures were improved following certain observations. VO2 was equally found to be sensitive to small temperature gradients in addition of being highly dependent upon high deposition temperatures. Finally, the use of different substrates has subsequently shown that the film composition and microstructure can be altered. After mastering the deposition of thin VO2 films, we explored another path that we found to be quite innovative. A relatively new deposition technique called HiPIMS was put to the test based on its new characteristics, leading to believe that it had the

  8. H/sup -/ beam emittance measurements for the penning and the asymmetric, grooved magnetron surface-plasma sources

    SciTech Connect

    Smith, H.V. Jr.; Allison, P.W.

    1981-01-01

    Beam-intensity and emittance measurements show that the H/sup -/ beam from our Penning surface-plasma source (SPS) has twice the intensity and ten times the brightness of the H/sup -/ beam from an asymmetric, grooved magnetron SPS. We deduce H/sup -/ ion temperatures of 5 eV for the Penning SPS and 22 eV for the asymmetric, grooved magnetron.

  9. Investigation of Influence of Gas Ratio on the Electron Temperature in TiN Magnetron Sputtering Deposition System

    DTIC Science & Technology

    2013-07-01

    31st ICPIG, July 14-19, 2013, Granada, Spain Investigation of Influence of Gas Ratio on the Electron Temperature in TiN Magnetron Sputtering ...Iran. In this work, a nanolayer of titanium nitride which produced by the magnetron sputtering system is synthesized. Moreover the effect of...Direct current (DC) sputtering has become a very popular technique to develop a wide variety of thin films including nitrides. Using this method

  10. Study on the influence of the magnetron power supply on the properties of the Silicon Nitride films

    NASA Astrophysics Data System (ADS)

    Kiseleva, D. V.; Yurjev, Y. N.; Petrakov, Y. V.; Sidelev, D. V.; Korzhenko, D. V.; Erofeev, E. V.

    2017-01-01

    Silicon nitride (Si3N4) films were deposited by magnetron sputtering of silicon target in (Ar+N2) atmosphere with refractive index 1.95 - 2.05. The results of Fourier transform infrared (FTIR) spectrophotometry showed Si-N bonds in the thin films with concentration 2.41·1023 – 3.48·1023 cm-3. Dependences of deposition rate, optical characteristics and surface morphology on rate of N2 flow and properties of magnetron power supply.

  11. Effect of Argon/Oxygen Flow Rate Ratios on DC Magnetron Sputtered Nano Crystalline Zirconium Titanate Thin Films

    NASA Astrophysics Data System (ADS)

    Rani, D. Jhansi; Kumar, A. GuruSampath; Sarmash, T. Sofi; Chandra Babu Naidu, K.; Maddaiah, M.; Rao, T. Subba

    2016-06-01

    High transmitting, non absorbent, nano crystalline zirconium titanate (ZT) thin films suitable for anti reflection coatings (ARC) were deposited on to glass substrates by direct current (DC) magnetron reactive sputtering technique, under distinct Argon to Oxygen (Ar/O2) gas flow rate ratios of 31/1, 30/2, 29/3 and 28/4, with a net gas flow (Ar + O2) of 32sccm, at an optimum substrate temperature of 250°C. The influence of the gas mixture ratio on the film properties has been investigated by employing x-ray diffraction (XRD), ultra violet visible (UV-vis) spectroscopy, atomic force microscopy (AFM), energy dispersive x-ray analysis (EDX) and four point probe methods. The films showed a predominant peak at 30.85° with (111) orientation. The crystallite size reduced from 22.94 nm to 13.5 nm and the surface roughness increased from 11.53 nm to 50.58 nm with increase in oxygen content respectively. The films deposited at 31/1 and 30/2 showed almost similar chemical composition. Increased oxygen content results an increase in electrical resistivity from 3.59 × 103 to 2.1 × 106 Ωm. The film deposited at Ar/O2 of 28/4 exhibited higher average optical transmittance of 91%, but its refractive index is higher than that of what is required for ARC. The films deposited at 31/1 and 30/2 of Ar/O2 possess higher transmittance (low absorbance) apart from suitable refractive index. Thus, these films are preferable candidates for ARC.

  12. Physicochemical model for reactive sputtering of hot target

    NASA Astrophysics Data System (ADS)

    Shapovalov, Viktor I.; Karzin, Vitaliy V.; Bondarenko, Anastasia S.

    2017-02-01

    A physicochemical model for reactive magnetron sputtering of a metal target is described in this paper. The target temperature in the model is defined as a function of the ion current density. Synthesis of the coating occurs due to the surface chemical reaction. The law of mass action, the Langmuir isotherm and the Arrhenius equation for non-isothermal conditions were used for mathematical description of the reaction. The model takes into consideration thermal electron emission and evaporation of the target surface. The system of eight algebraic equations, describing the model, was solved for the tantalum target sputtered in the oxygen environment. It was established that the hysteresis effect disappears with the increase of the ion current density.

  13. Formation of cubic boron-nitride by the reactive sputter deposition of boron

    SciTech Connect

    Jankowski, A.F.; Hayes, J.P.; Makowiecki, D.W.; McKeman, M.A.

    1997-03-01

    Boron-nitride films are synthesized by RF magnetron sputtering boron targets where the deposition parameters of gas pressure, flow and composition are varied along with substrate temperature and applied bias. The films are analyzed using Auger electron spectroscopy, transmission electron microscopy, nanoindentation, Raman spectroscopy and x-ray absorption spectroscopy. These techniques provide characterization of film composition, crystalline structure, hardness and chemical bonding, respectively. Reactive, rf-sputtering process parameters are established which lead to the growth of crystalline BN phases. The deposition of stable and adherent boron nitride coatings consisting of the cubic phase requires 400 `C substrate heating and the application of a 300 V negative bias.

  14. Flash post-discharge emission in a reactive HiPIMS process

    NASA Astrophysics Data System (ADS)

    Loquai, S.; Zabeida, O.; Klemberg-Sapieha, J. E.; Martinu, L.

    2016-09-01

    In the present work, time-, space- and species-resolved optical emission spectroscopy has been applied to investigate post-pulse behavior of the reactive High Power Impulse Magnetron Sputtering (HiPIMS) process with a partially poisoned target. Following each pulse, at a high O2/Ar ratio, a well-defined post-discharge emission zone detaches from the target during the first few microseconds of the electron cool-down; this zone exhibits high emission intensity in the near-surface region, and it moves toward the substrate holder. We link this behavior to a localized high density of metastable molecular oxygen, and to the electron attachment dissociation of oxygen.

  15. Magneto-optical properties of yttrium iron garnet (YIG) thin films elaborated by radio frequency sputtering

    NASA Astrophysics Data System (ADS)

    Boudiar, T.; Payet-Gervy, B.; Blanc-Mignon, M.-F.; Rousseau, J.-J.; Le Berre, M.; Joisten, H.

    2004-12-01

    Thin films of yttrium iron garnet (YIG) are grown by radio frequency magnetron non reactive sputtering system. Thin films are crystallised by heat-treatment to obtain magneto-optical properties. On quartz substrate, the network of cracks observed on the annealed samples can be explained by the difference between the thermal expansion coefficient of substrate and YIG. Physico-chemical analysis shown that the obtained material has a correct stoichiometry and is crystallised as FCC. The Faraday rotation of thin films is measured with a classical ellipsometric system based on transmission which allows us to obtained an accuracy of 0.01 ° . The variation of Faraday rotation is studied on the one hand versus radio frequency power applied to the cathode during the deposition and on the other hand versus the applied magnetic field. The results are compared with those obtained by vibrating sample magnetometer analysis in perpendicular configuration. A maximum Faraday rotation is observed to be 1900 ° / cm at the wavelength of 594 nm for a YIG thin film formed on quartz substrate and annealed at 740 ° C . The values of the Faraday rotation coefficients obtained in the study versus the wavelength are comparable to those of the literature for the bulk material. In order to eliminate the stress due to the heat-treatment, we made some films on single crystals of gadolinium gallium garnet (1 1 1) substrates for which thermal expansion coefficient is near than the YIG one. The material crystallises with no crackles and the Faraday effect is equivalent.

  16. A roadmap for OH reactivity research

    NASA Astrophysics Data System (ADS)

    Williams, Jonathan; Brune, William

    2015-04-01

    A fundamental property of the atmosphere is the frequency of gas-phase reactions with the OH radical, the atmosphere's primary oxidizing agent. This reaction frequency is called the OH reactivity and is the inverse the lifetime of the OH radical itself, which varies from a few seconds in the clean upper troposphere to below 10 ms in forests and polluted city environments. Ever since the discovery of the OH radical's importance to tropospheric chemistry, the characterization of its overall loss rate (OH reactivity) has remained a key question. At first, this property was assessed by summing the reactivity contributions of individually measured compounds; however, as improving analytical technology revealed ever more reactive species in ambient air, it became clear that this approach could provide only a lower limit. Approximately 15 years ago, the direct measurement of total OH reactivity was conceived independently by two groups. The first publications demonstrated direct OH reactivity measurements in the laboratory (Calpini et al., 1999) based on LIDAR and in the ambient air (Kovacs and Brune, 2001) based on in situ laser induced fluorescence detection of OH.

  17. A review comparing cathodic arcs and high power impulse magnetron sputtering (HiPIMS)

    DOE PAGES

    Anders, André

    2014-09-02

    In this study, high power impulse magnetron sputtering (HiPIMS) has been in the center of attention over the last years as it is an emerging physical vapor deposition (PVD) technology that combines advantages of magnetron sputtering with various forms of energetic deposition of films such as ion plating and cathodic arc plasma deposition. It should not come at a surprise that many extension and variations of HiPIMS make use, intentionally or unintentionally, of previously discovered approaches to film processing such as substrate surface preparation by metal ion sputtering and phased biasing for film texture and stress control. Therefore, in thismore » review, an overview is given on some historical developments and features of cathodic arc and HiPIMS plasmas, showing commonalities and differences. To limit the scope, emphasis is put on plasma properties, as opposed to surveying the vast literature on specific film materials and their properties.« less

  18. A review comparing cathodic arcs and high power impulse magnetron sputtering (HiPIMS)

    SciTech Connect

    Anders, André

    2014-09-02

    In this study, high power impulse magnetron sputtering (HiPIMS) has been in the center of attention over the last years as it is an emerging physical vapor deposition (PVD) technology that combines advantages of magnetron sputtering with various forms of energetic deposition of films such as ion plating and cathodic arc plasma deposition. It should not come at a surprise that many extension and variations of HiPIMS make use, intentionally or unintentionally, of previously discovered approaches to film processing such as substrate surface preparation by metal ion sputtering and phased biasing for film texture and stress control. Therefore, in this review, an overview is given on some historical developments and features of cathodic arc and HiPIMS plasmas, showing commonalities and differences. To limit the scope, emphasis is put on plasma properties, as opposed to surveying the vast literature on specific film materials and their properties.

  19. Resistive switching behavior of RF magnetron sputtered ZnO thin films

    SciTech Connect

    Rajalakshmi, R.; Angappane, S.

    2015-06-24

    The resistive switching characteristics of RF magnetron sputtered zinc oxide thin films have been studied. The x-ray diffraction studies confirm the formation of crystalline ZnO on Pt/TiO{sub 2}/SiO{sub x}/Si substrate. We have fabricated Cu/ZnO/Pt device using a shadow masking technique for resistive switching study. Our Cu/ZnO/Pt device exhibits a unipolar resistive switching behaviour. The switching observed in our device could be related to oxygen vacancies or Cu ions that generate the conducting filaments responsible for resistive switching. We found HRS to LRS resistance ratio of as high as ∼200 for our Cu/ZnO/Pt device. The higher resistance ratio and stability of Cu/ZnO/Pt device would make our RF magnetron sputtered zinc oxide thin films suitable for non volatile memory applications.

  20. Magnetron sputtered boron films for increasing hardness of a metal surface

    DOEpatents

    Makowiecki, Daniel M.; Jankowski, Alan F.

    2003-05-27

    A method is described for the production of thin boron and titanium/boron films by magnetron sputter deposition. The amorphous boron films contain no morphological growth features, unlike those found when thin films are prepared by various physical vapor deposition processes. Magnetron sputter deposition method requires the use of a high density crystalline boron sputter target which is prepared by hot isostatic pressing. Thin boron films prepared by this method are useful for producing hardened surfaces, surfacing machine tools, etc. and for ultra-thin band pass filters as well as the low Z element in low Z/high Z optical components, such as mirrors which enhance reflectivity from grazing to normal incidence.

  1. High power pulsed magnetron sputtering: A method to increase deposition rate

    SciTech Connect

    Raman, Priya McLain, Jake; Ruzic, David N; Shchelkanov, Ivan A.

    2015-05-15

    High power pulsed magnetron sputtering (HPPMS) is a state-of-the-art physical vapor deposition technique with several industrial applications. One of the main disadvantages of this process is its low deposition rate. In this work, the authors report a new magnetic field configuration, which produces deposition rates twice that of conventional magnetron's dipole magnetic field configuration. Three different magnet pack configurations are discussed in this paper, and an optimized magnet pack configuration for HPPMS that leads to a higher deposition rate and nearly full-face target erosion is presented. The discussed magnetic field produced by a specially designed magnet assembly is of the same size as the conventional magnet assembly and requires no external fields. Comparison of deposition rates with different power supplies and the electron trapping efficiency in complex magnetic field arrangements are discussed.

  2. Characterization thin films TiO2 obtained in the magnetron sputtering process

    NASA Astrophysics Data System (ADS)

    Kamiński, Maciej; Firek, Piotr; Caban, Piotr

    2016-12-01

    The aim of the study was to elucidate influence parameters of magnetron sputtering process on growth rate and quality of titanium dioxide thin films. TiO2 films were produced on two inch silicon wafers by means of magnetron sputtering method. Characterization of samples was performed using ellipsometer and atomic force microscope (AFM). Currentvoltage (I-V) and capacitance-voltage (C-V) measurements were also carried out. The results enable to determine impact of pressure, power, gases flow and process duration on the physical parameters obtained layers such as electrical permittivity, flat band voltage and surface topography. Experiments were designed according to orthogonal array Taguchi method. Respective trends impact were plotted.

  3. Discharge parameters and dominant electron conductivity mechanism in a low-pressure planar magnetron discharge

    SciTech Connect

    Baranov, O.; Romanov, M.; Ostrikov, Kostya

    2009-06-15

    Parameters of a discharge sustained in a planar magnetron configuration with crossed electric and magnetic fields are studied experimentally and numerically. By comparing the data obtained in the experiment with the results of calculations made using the proposed theoretical model, conclusion was made about the leading role of the turbulence-driven Bohm electron conductivity in the low-pressure operation mode (up to 1 Pa) of the discharge in crossed electric and magnetic fields. A strong dependence of the width of the cathode sputter trench, associated with the ionization region of the magnetron discharge, on the discharge parameters was observed in the experiments. The experimental data were used as input parameters in the discharge model that describes the motion of secondary electrons across the magnetic field in the ionization region and takes into account the classical, near-wall, and Bohm mechanisms of electron conductivity.

  4. Pseudo-3D PIC modeling of drift-induced spatial inhomogeneities in planar magnetron plasmas

    NASA Astrophysics Data System (ADS)

    Revel, A.; Minea, T.; Tsikata, S.

    2016-10-01

    A pseudo-3D modeling approach, based on a particle-in-cell (PIC)-Monte Carlo collisions algorithm, has been developed for the study of large- and short-scale organization of the plasma in a planar magnetron. This extension of conventional PIC modeling permits the observation of spontaneous organization of the magnetron plasma, under the influence of crossed electric and magnetic fields, into the well-known, large-scale regions of enhanced ionization and density known as spokes. The nature of complex three-dimensional electron trajectories around such structures, and non-uniform ionization within them, is revealed. This modeling provides direct numerical evidence for the existence of high-amplitude internal spoke electric fields, proposed in earlier works. A 3D phenomenological model, consistent with numerical results, is proposed. Electron density fluctuations in the megahertz range, with characteristics similar to the electron cyclotron drift instability experimentally identified in a recent Letter, are also found.

  5. Performance Characterization of a Solenoid-type Gas Valve for the H- Magnetron Source at FNAL

    SciTech Connect

    Sosa, A.; Bollinger, D. S.; Karns, P. R.

    2016-09-06

    The magnetron-style H- ion sources currently in operation at Fermilab use piezoelectric gas valves to function. This kind of gas valve is sensitive to small changes in ambient temperature, which affect the stability and performance of the ion source. This motivates the need to find an alternative way of feeding H2 gas into the source. A solenoid-type gas valve has been characterized in a dedicated off-line test stand to assess the feasibility of its use in the operational ion sources. H- ion beams have been extracted at 35 keV using this valve. In this study, the performance of the solenoid gas valve has been characterized measuring the beam current output of the magnetron source with respect to the voltage and pulse width of the signal applied to the gas valve.

  6. Microstructural evaluation of NiTi-based films deposited by magnetron sputtering

    SciTech Connect

    Crăciunescu, Corneliu M. Mitelea, Ion Budău, Victor; Ercuţa, Aurel

    2014-11-24

    Shape memory alloy films belonging to the NiTi-based systems were deposited on heated and unheated substrates, by magnetron sputtering in a custom made system, and their structure and composition was analyzed using electron microscopy. Several substrates were used for the depositions: glass, Cu-Zn-Al, Cu-Al-Ni and Ti-NiCu shape memory alloy ribbons and kapton. The composition of the Ti-Ni-Cu films showed limited differences, compared to the one of the target and the microstructure for the DC magnetron sputtering revealed crystallized structure with features determined on peel off samples from a Si wafer. Both inter and transcrystalline fractures were observed and related to the interfacial stress developed on cooling from deposition temperature.

  7. The microstructure and properties of titanium dioxide films synthesized by unbalanced magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Leng, Y. X.; Chen, J. Y.; Yang, P.; Sun, H.; Huang, N.

    2007-04-01

    In this work, titanium oxide films were deposited on Ti6Al4V and Si (1 0 0) by DC unbalanced magnetron sputtering method at different oxygen pressure. X-ray diffraction (XRD), microhardness tests, pin-on-disk wear experiments, surface contact angle tests and platelet adhesion investigation were conducted to evaluate the properties of the films. The corrosion behavior of titanium dioxide films was characterized by potentiodynamic polarization. The results showed that titanium oxide films deposited by unbalance magnetron sputtering were compact and could obviously enhance microhardness, wear resistance of titanium alloy substrate. Potentiodynamic polarization curves showed that Ti-6Al-4V deposited with titanium dioxide films had lower dissolution currents than that of the uncoated one. The results of in vitro hemocompatibility analyses indicated that the blood compatibility of the titanium dioxide films with bandgap 3.2 eV have better blood compatibility.

  8. Power-combining based on master-slave injection-locking magnetron

    NASA Astrophysics Data System (ADS)

    Ping, Yuan; Yi, Zhang; Wenjun, Ye; Huacheng, Zhu; Kama, Huang; Yang, Yang

    2016-07-01

    A microwave power-combining system composed of two Panasonic 2M244-M1 magnetrons based on master-slave injection-locking is demonstrated in this paper. The principle of master-slave injection-locking and the locking condition are theoretical analyzed. Experimental results are consistent with the theoretical analysis and the experimental combined efficiency is higher than 96%. Compared with the external-injection-locked system, the power-combining based on the master-slave injection-locking magnetron is superior by taking out the external solid-state driver and the real-time phase control system. Thus, this power-combining system has great potential for obtaining a high efficiency, high stability, low cost, and high power microwave source. Project supported by the National Basic Research Program of China (Grant No. 2013CB328902) and the National Natural Science Foundation of China (Grant No. 61501311).

  9. Analytic model of the energy distribution function for highly energetic electrons in magnetron plasmas

    SciTech Connect

    Gallian, Sara Trieschmann, Jan; Mussenbrock, Thomas; Brinkmann, Ralf Peter; Hitchon, William N. G.

    2015-01-14

    This paper analyzes a situation which is common for magnetized technical plasmas such as dc magnetron discharges and high power impulse magnetron sputtering (HiPIMS) systems, where secondary electrons enter the plasma after being accelerated in the cathode fall and encounter a nearly uniform bulk. An analytic calculation of the distribution function of hot electrons is presented; these are described as an initially monoenergetic beam that slows down by Coulomb collisions with a Maxwellian distribution of bulk (cold) electrons, and by inelastic collisions with neutrals. Although this analytical solution is based on a steady-state assumption, a comparison of the characteristic time-scales suggests that it may be applicable to a variety of practical time-dependent discharges, and it may be used to introduce kinetic effects into models based on the hypothesis of Maxwellian electrons. The results are verified for parameters appropriate to HiPIMS discharges, by means of time-dependent and fully kinetic numerical calculations.

  10. Are the argon metastables important in high power impulse magnetron sputtering discharges?

    SciTech Connect

    Gudmundsson, J. T.; Lundin, D.; Minea, T. M.; Stancu, G. D.; Brenning, N.

    2015-11-15

    We use an ionization region model to explore the ionization processes in the high power impulse magnetron sputtering (HiPIMS) discharge in argon with a titanium target. In conventional dc magnetron sputtering (dcMS), stepwise ionization can be an important route for ionization of the argon gas. However, in the HiPIMS discharge stepwise ionization is found to be negligible during the breakdown phase of the HiPIMS pulse and becomes significant (but never dominating) only later in the pulse. For the sputtered species, Penning ionization can be a significant ionization mechanism in the dcMS discharges, while in the HiPIMS discharge Penning ionization is always negligible as compared to electron impact ionization. The main reasons for these differences are a higher plasma density in the HiPIMS discharge, and a higher electron temperature. Furthermore, we explore the ionization fraction and the ionized flux fraction of the sputtered vapor and compare with recent experimental work.

  11. Equibrium and Stability of the Brillouin Flow in Recirculating Planar Magnetron

    NASA Astrophysics Data System (ADS)

    Simon, D. H.; Lau, Y. Y.; Franzi, M.; Greening, G.; Gilgenbach, R. M.; Luginsland, J. W.

    2011-10-01

    Simulation of the novel recirculating planar magnetron, RPM, has shown rapid formation of electron bunches in the inverted magnetron configuration. This bunching mechanism was recently simulated in a thin electron layer model, which exhibited negative, positive, and infinite mass behavior, depending on the magnitude and sign of the radial electric field. We analyze these properties for the relativistic, cylindrical Brillouin flow, to evaluate RPM startup. We make use of our recent discovery that the electrostatic potential and the vector potential satisfy a Buneman-Hartree like relation, and a Hull-cutoff like relation EVERYWHERE within the equilibrium Brillouin flow. This work was supported by AFOSR, L-3 Communications Electron Devices, and Northrop Grumman Corporation.

  12. Structural and dielectric studies of Co doped MgTiO3 thin films fabricated by RF magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Kumar, T. Santhosh; Gogoi, P.; Thota, S.; Pamu, D.

    2014-06-01

    We report the structural, dielectric and leakage current properties of Co doped MgTiO3 thin films deposited on platinized silicon (Pt/TiO2/SiO2/Si) substrates by RF magnetron sputtering. The role of oxygen mixing percentage (OMP) on the growth, morphology, electrical and dielectric properties of the thin films has been investigated. A preferred orientation of grains along (110) direction has been observed with increasing the OMP. Such evolution of the textured growth is explained on the basis of the orientation factor analysis followed the Lotgering model. (Mg1-xCox)TiO3 (x = 0.05) thin films exhibits a maximum relative dielectric permittivity of ɛr = 12.20 and low loss (tan δ ˜ 1.2 × 10-3) over a wide range of frequencies for 75% OMP. The role of electric field frequency (f) and OMP on the ac-conductivity of (Mg0.95Co0.05)TiO3 have been studied. A progressive increase in the activation energy (Ea) and relative permittivity ɛr values have been noticed up to 75% of OMP, beyond which the properties starts deteriorate. The I-V characteristics reveals that the leakage current density decreases from 9.93 × 10-9 to 1.14 × 10-9 A/cm2 for OMP 0% to 75%, respectively for an electric field strength of 250 kV/cm. Our experimental results reveal up to that OMP ≥ 50% the leakage current mechanism is driven by the ohmic conduction, below which it is dominated by the schottky emission.

  13. Modelling and Optimization of Technological Process for Magnetron Synthesis of Altin Nanocomposite Films on Cutting Tools

    NASA Astrophysics Data System (ADS)

    Kozhina, T. D.

    2016-04-01

    The paper highlights the results of the research on developing the mechanism to model the technological process for magnetron synthesis of nanocomposite films on cutting tools, which provides their specified physical and mechanical characteristics by controlling pulsed plasma parameters. The paper presents optimal conditions for AlTiN coating deposition on cutting tools according to the ion energy of sputtered atoms in order to provide their specified physical and mechanical characteristics.

  14. MeV electron irradiation of Si-SiO2 structures with magnetron sputtered oxide

    NASA Astrophysics Data System (ADS)

    Kaschieva, S.; Angelov, Ch; Dmitriev, S. N.

    2016-03-01

    MeV electrons influence on the characteristics of Si-SiO2 structure with magnetron sputtered oxide was studied by ellipsometry and the thermally stimulated current (TSC) method. The MOS structures used in this study were fabricated on <100> oriented p-Si wafers of 12.75-17,25 Ω.cm resistivity. Magnetron sputtered oxides with different thicknesses of 20 and 100 nm were deposited on p-Si substrates. Both groups of samples were irradiated by 23 MeV electrons. The oxide thicknesses and TSC characteristics of the MOS samples were measured before and after MeV electron irradiation with doses of 4.8×1015 and 4.8×1016 el.cm-2. The oxide thicknesses of both groups of samples increased after irradiation. The main defects generated by the MeV electrons were evaluated. It was shown that the trap concentration increases with the electron irradiation dose. The main peak in the TSC characteristics gives information about the main radiation defects at the Si-SiO2 interface of the MOS structures. These defects can be related to the vacancy-boron complexes which are associated with the main impurities in the p-Si substrate. These results correspond to our results reported earlier for MeV electron irradiated Si-SiO2 structures with thermally grown oxide. But (in this case) the effects observed are more pronounced for the magnetron sputtered oxide. A possible reason is the higher defect concentration generated in the magnetron sputtered oxide during its deposition on Si-substrates.

  15. Plasma potential of a moving ionization zone in DC magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Panjan, Matjaž; Anders, André

    2017-02-01

    Using movable emissive and floating probes, we determined the plasma and floating potentials of an ionization zone (spoke) in a direct current magnetron sputtering discharge. Measurements were recorded in a space and time resolved manner, which allowed us to make a three-dimensional representation of the plasma potential. From this information we could derive the related electric field, space charge, and the related spatial distribution of electron heating. The data reveal the existence of strong electric fields parallel and perpendicular to the target surface. The largest E-fields result from a double layer structure at the leading edge of the ionization zone. We suggest that the double layer plays a crucial role in the energization of electrons since electrons can gain several 10 eV of energy when crossing the double layer. We find sustained coupling between the potential structure, electron heating, and excitation and ionization processes as electrons drift over the magnetron target. The brightest region of an ionization zone is present right after the potential jump, where drifting electrons arrive and where most local electron heating occurs. The ionization zone intensity decays as electrons continue to drift in the Ez × B direction, losing energy by inelastic collisions; electrons become energized again as they cross the potential jump. This results in the elongated, arrowhead-like shape of the ionization zone. The ionization zone moves in the -Ez × B direction from which the to-be-heated electrons arrive and into which the heating region expands; the zone motion is dictated by the force of the local electric field on the ions at the leading edge of the ionization zone. We hypothesize that electron heating caused by the potential jump and physical processes associated with the double layer also apply to magnetrons at higher discharge power, including high power impulse magnetron sputtering.

  16. Overview of Recent Studies and Design Changes for the FNAL Magnetron Ion Source

    SciTech Connect

    Bollinger, D. S.; Sosa, A.

    2016-09-06

    This paper will cover several studies and design changes that will eventually be implemented to the Fermi National Accelerator Laboratory (FNAL) magnetron ion source. The topics include tungsten cathode insert, solenoid gas valves, current controlled arc pulser, cesium boiler redesign, gas mixtures of hydrogen and nitrogen, and duty factor reduction. The studies were performed on the FNAL test stand described in [1], with the aim to improve source lifetime, stability, and reducing the amount of tuning needed.

  17. Measuring the energy flux at the substrate position during magnetron sputter deposition processes

    SciTech Connect

    Cormier, P.-A.; Thomann, A.-L.; Dussart, R.; Semmar, N.; Mathias, J.; Balhamri, A.; Snyders, R.; Konstantinidis, S.

    2013-01-07

    In this work, the energetic conditions at the substrate were investigated in dc magnetron sputtering (DCMS), pulsed dc magnetron sputtering (pDCMS), and high power impulse magnetron sputtering (HiPIMS) discharges by means of an energy flux diagnostic based on a thermopile sensor, the probe being set at the substrate position. Measurements were performed in front of a titanium target for a highly unbalanced magnetic field configuration. The average power was always kept to 400 W and the probe was at the floating potential. Variation of the energy flux against the pulse peak power in HiPIMS was first investigated. It was demonstrated that the energy per deposited titanium atom is the highest for short pulses (5 {mu}s) high pulse peak power (39 kW), as in this case, the ion production is efficient and the deposition rate is reduced by self-sputtering. As the argon pressure is increased, the energy deposition is reduced as the probability of scattering in the gas phase is increased. In the case of the HiPIMS discharge run at moderate peak power density (10 kW), the energy per deposited atom was found to be lower than the one measured for DCMS and pDCMS discharges. In these conditions, the HiPIMS discharge could be characterized as soft and close to a pulsed DCMS discharge run at very low duty cycle. For the sake of comparison, measurements were also carried out in DCMS mode with a balanced magnetron cathode, in the same working conditions of pressure and power. The energy flux at the substrate is significantly increased as the discharge is generated in an unbalanced field.

  18. Automated diagnostics of a magnetron discharge plasma based on atomic molecular emission spectra

    NASA Astrophysics Data System (ADS)

    Gradov, V. M.; Zimin, A. M.; Krivitskiy, S. E.; Serushkin, S. V.; Troynov, V. I.

    2012-12-01

    A software-hardware complex intended for investigating spatial distributions of the plasma spectral emissivity is described. It allows us to record and identify the lines and systems of molecular bands in an automatic mode and to perform computer processing of spectra. Molecular bands of deuterium for different electronic-vibrational-rotational transitions are identified. The excitation temperatures of atomic levels, translational, rotational and vibrational temperatures are estimated for a discharge in a planar magnetron.

  19. Modular deposition chamber for in situ X-ray experiments during RF and DC magnetron sputtering.

    PubMed

    Krause, Bärbel; Darma, Susan; Kaufholz, Marthe; Gräfe, Hans Hellmuth; Ulrich, Sven; Mantilla, Miguel; Weigel, Ralf; Rembold, Steffen; Baumbach, Tilo

    2012-03-01

    A new sputtering system for in situ X-ray experiments during DC and RF magnetron sputtering is described. The outstanding features of the system are the modular design of the vacuum chamber, the adjustable deposition angle, the option for plasma diagnostics, and the UHV sample transfer in order to access complementary surface analysis methods. First in situ diffraction and reflectivity measurements during RF and DC deposition of vanadium carbide demonstrate the performance of the set-up.

  20. Influence of pulse duration on the plasma characteristics in high-power pulsed magnetron discharges

    SciTech Connect

    Konstantinidis, S.; Dauchot, J.P.; Ganciu, M.; Ricard, A.; Hecq, M.

    2006-01-01

    High-power pulsed magnetron discharges have drawn an increasing interest as an approach to produce highly ionized metallic vapor. In this paper we propose to study how the plasma composition and the deposition rate are influenced by the pulse duration. The plasma is studied by time-resolved optical emission and absorption spectroscopies and the deposition rate is controlled thanks to a quartz microbalance. The pulse length is varied between 2.5 and 20 {mu}s at 2 and 10 mTorr in pure argon. The sputtered material is titanium. For a constant discharge power, the deposition rate increases as the pulse length decreases. With 5 {mu}s pulse, for an average power of 300 W, the deposition rate is {approx}70% of the deposition rate obtained in direct current magnetron sputtering at the same power. The increase of deposition rate can be related to the sputtering regime. For long pulses, self-sputtering seems to occur as demonstrated by time-resolved optical emission diagnostic of the discharge. In contrary, the metallic vapor ionization rate, as determined by absorption measurements, diminishes as the pulses are shortened. Nevertheless, the ionization rate is in the range of 50% for 5 {mu}s pulses while it lies below 10% in the case of a classical continuous magnetron discharge.

  1. Simulation of the electric potential and plasma generation coupling in magnetron sputtering discharges

    NASA Astrophysics Data System (ADS)

    Trieschmann, Jan; Krueger, Dennis; Schmidt, Frederik; Brinkmann, Ralf Peter; Mussenbrock, Thomas

    2016-09-01

    Magnetron sputtering typically operated at low pressures below 1 Pa is a widely applied deposition technique. For both, high power impulse magnetron sputtering (HiPIMS) as well as direct current magnetron sputtering (dcMS) the phenomenon of rotating ionization zones (also referred to as spokes) has been observed. A distinct spatial profile of the electric potential has been associated with the latter, giving rise to low, mid, and high energy groups of ions observed at the substrate. The adherent question of which mechanism drives this process is still not fully understood. This query is approached using Monte Carlo simulations of the heavy particle (i.e., ions and neutrals) transport consistently coupled to a pre-specified electron density profile via the intrinsic electric field. The coupling between the plasma generation and the electric potential, which establishes correspondingly, is investigated. While the system is observed to strive towards quasi-neutrality, distinct mechanisms governing the shape of the electric potential profile are identified. This work is supported by the German Research Foundation (DFG) in the frame of the transregional collaborative research centre TRR 87.

  2. Magnetic control of breakdown: Toward energy-efficient hollow-cathode magnetron discharges

    SciTech Connect

    Baranov, O.; Romanov, M.; Kumar, S.; Zong, X. X.; Ostrikov, K.

    2011-03-15

    Characteristics of electrical breakdown of a planar magnetron enhanced with an electromagnet and a hollow-cathode structure, are studied experimentally and numerically. At lower pressures the breakdown voltage shows a dependence on the applied magnetic field, and the voltage necessary to achieve the self-sustained discharge regime can be significantly reduced. At higher pressures, the dependence is less sensitive to the magnetic field magnitude and shows a tendency of increased breakdown voltage at the stronger magnetic fields. A model of the magnetron discharge breakdown is developed with the background gas pressure and the magnetic field used as parameters. The model describes the motion of electrons, which gain energy by passing the electric field across the magnetic field and undergo collisions with neutrals, thus generating new bulk electrons. The electrons are in turn accelerated in the electric field and effectively ionize a sufficient amount of neutrals to enable the discharge self-sustainment regime. The model is based on the assumption about the combined classical and near-wall mechanisms of electron conductivity across the magnetic field, and is consistent with the experimental results. The obtained results represent a significant advance toward energy-efficient multipurpose magnetron discharges.

  3. S-band relativistic magnetron operation with an active plasma cathode

    SciTech Connect

    Hadas, Y.; Sayapin, A.; Kweller, T.; Krasik, Ya. E.

    2009-04-15

    Results of experimental research on a relativistic S-band magnetron with a ferroelectric plasma source as a cathode are presented. The cathode plasma was generated using a driving pulse (approx3 kV, 200 ns) applied to the ferroelectric cathode electrodes via inductive decoupling prior to the beginning of an accelerating pulse (200 kV, 150 ns) delivered by a linear induction accelerator. The magnetron and generated microwave radiation parameters obtained for the ferroelectric plasma cathode and the explosive emission plasma were compared. It was shown that the application of the ferroelectric plasma cathode allows one to avoid a time delay in the appearance of the electron emission to achieve a better matching between the magnetron and linear induction accelerator impedances and to increase significantly (approx30%) the duration of the microwave pulse with an approx10% increase in the microwave power. The latter results in the microwave radiation generation being 30% more efficient than when the explosive emission cathode is used, where efficiency does not exceed 20%.

  4. Fabrication and characterization of flaky core-shell particles by magnetron sputtering silver onto diatomite

    NASA Astrophysics Data System (ADS)

    Wang, Yuanyuan; Zhang, Deyuan; Cai, Jun

    2016-02-01

    Diatomite has delicate porous structures and various shapes, making them ideal templates for microscopic core-shell particles fabrication. In this study, a new process of magnetron sputtering assisted with photoresist positioning was proposed to fabricate lightweight silver coated porous diatomite with superior coating quality and performance. The diatomite has been treated with different sputtering time to investigate the silver film growing process on the surface. The morphologies, constituents, phase structures and surface roughness of the silver coated diatomite were analyzed with SEM, EDS, XRD and AFM respectively. The results showed that the optimized magnetron sputtering time was 8-16 min, under which the diatomite templates were successfully coated with uniform silver film, which exhibits face centered cubic (fcc) structure, and the initial porous structures were kept. Moreover, this silver coating has lower surface roughness (RMS 4.513 ± 0.2 nm) than that obtained by electroless plating (RMS 15.692 ± 0.5 nm). And the infrared emissivity of coatings made with magnetron sputtering and electroless plating silver coated diatomite can reach to the lowest value of 0.528 and 0.716 respectively.

  5. Fabrication of Optical Multilayer Devices from Porous Silicon Coatings with Closed Porosity by Magnetron Sputtering.

    PubMed

    Caballero-Hernández, Jaime; Godinho, Vanda; Lacroix, Bertrand; Jiménez de Haro, Maria C; Jamon, Damien; Fernández, Asunción

    2015-07-01

    The fabrication of single-material photonic-multilayer devices is explored using a new methodology to produce porous silicon layers by magnetron sputtering. Our bottom-up methodology produces highly stable amorphous porous silicon films with a controlled refractive index using magnetron sputtering and incorporating a large amount of deposition gas inside the closed pores. The influence of the substrate bias on the formation of the closed porosity was explored here for the first time when He was used as the deposition gas. We successfully simulated, designed, and characterized Bragg reflectors and an optical microcavity that integrates these porous layers. The sharp interfaces between the dense and porous layers combined with the adequate control of the refractive index and thickness allowed for excellent agreement between the simulation and the experiments. The versatility of the magnetron sputtering technique allowed for the preparation of these structures for a wide range of substrates such as polymers while also taking advantage of the oblique angle deposition to prepare Bragg reflectors with a controlled lateral gradient in the stop band wavelengths.

  6. Phenylethynyl reactive diluents

    NASA Technical Reports Server (NTRS)

    Bryant, Robert G. (Inventor); Jensen, Brian J. (Inventor); Hergenrother, Paul M. (Inventor)

    1995-01-01

    A composition of matter having a specified general structure is employed to terminate a nucleophilic reagent, resulting in the exclusive production of phenylethynyl terminated reactive oligomers which display unique thermal characteristics. A reactive diluent having a specified general structure is employed to decrease the melt viscosity of a phenylethynyl terminated reactive oligomer and to subsequently react with to provide a thermosetting material of enhanced density. These materials have features which make them attractive candidates for use as composite matrices and adhesives.

  7. Reactive multilayers fabricated by vapor deposition. A critical review

    SciTech Connect

    Adams, D. P.

    2014-10-02

    The reactive multilayer thin films are a class of energetic materials that continue to attract attention for use in joining applications and as igniters. Generally composed of two reactants, these heterogeneous solids can be stimulated by an external source to promptly release stored chemical energy in a sudden emission of light and heat. In our critical review article, results from recent investigations of these materials are discussed. Discussion begins with a brief description of the vapor deposition techniques that provide accurate control of layer thickness and film composition. More than 50 reactive film compositions have been reported to date, with most multilayers fabricated by magnetron sputter deposition or electron-beam evaporation. In later sections, we review how multilayer ignition threshold, reaction rate, and total heat are tailored via thin film design. For example, planar multilayers with nanometer-scale periodicity exhibit rapid, self-sustained reactions with wavefront velocities up to 100 m/s. Numeric and analytical models have elucidated many of the fundamental processes that underlie propagating exothermic reactions while demonstrating how reaction rates vary with multilayer design. Recent, time-resolved diffraction and imaging studies have further revealed the phase transformations and the wavefront dynamics associated with propagating chemical reactions. Many reactive multilayers (e.g., Co/Al) form product phases that are consistent with published equilibrium phase diagrams, yet a few systems, such as Pt/Al, develop metastable products. The final section highlights current and emerging applications of reactive multilayers. Examples include reactive Ni(V)/Al and Pd/Al multilayers which have been developed for localized soldering of heat-sensitive components.

  8. Reactive multilayers fabricated by vapor deposition. A critical review

    DOE PAGES

    Adams, D. P.

    2014-10-02

    The reactive multilayer thin films are a class of energetic materials that continue to attract attention for use in joining applications and as igniters. Generally composed of two reactants, these heterogeneous solids can be stimulated by an external source to promptly release stored chemical energy in a sudden emission of light and heat. In our critical review article, results from recent investigations of these materials are discussed. Discussion begins with a brief description of the vapor deposition techniques that provide accurate control of layer thickness and film composition. More than 50 reactive film compositions have been reported to date, withmore » most multilayers fabricated by magnetron sputter deposition or electron-beam evaporation. In later sections, we review how multilayer ignition threshold, reaction rate, and total heat are tailored via thin film design. For example, planar multilayers with nanometer-scale periodicity exhibit rapid, self-sustained reactions with wavefront velocities up to 100 m/s. Numeric and analytical models have elucidated many of the fundamental processes that underlie propagating exothermic reactions while demonstrating how reaction rates vary with multilayer design. Recent, time-resolved diffraction and imaging studies have further revealed the phase transformations and the wavefront dynamics associated with propagating chemical reactions. Many reactive multilayers (e.g., Co/Al) form product phases that are consistent with published equilibrium phase diagrams, yet a few systems, such as Pt/Al, develop metastable products. The final section highlights current and emerging applications of reactive multilayers. Examples include reactive Ni(V)/Al and Pd/Al multilayers which have been developed for localized soldering of heat-sensitive components.« less

  9. Improvement of corrosion protection property of Mg-alloy by DLC and Si-DLC coatings with PBII technique and multi-target DC-RF magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Masami, Ikeyama; Setsuo, Nakao; Tsutomu, Sonoda; Junho, Choi

    2009-05-01

    Magnesium alloys have been considered as one of the most promising light weight materials with potential applications for automobile and aircraft components. Their poor corrosion resistance, however, has to date prevented wider usage. Diamond-like carbon (DLC) and silicon-incorporated DLC (Si-DLC) coatings are known to provide a high degree of corrosion protection, and hold accordingly promise for enhancing the corrosion resistance of the magnesium alloys. In this work we have studied the effect of coating conditions of DLC coatings as well as Si incorporation into coating on corrosion resistance, deposited onto AZ91 magnesium alloy substrates by plasma based ion implantation (PBII). The influences of a Ti interlayer beneath the DLC, Si-DLC and Ti incorporated DLC (Ti-DLC) coatings fabricated by multi-target direct-current radio-frequency (DC-RF) magnetron sputtering were also examined on both the adhesion strength and corrosion resistance of the materials. We have also examined the effect of the Si content in the Si-DLC coatings made by magnetron sputtering on the alloys' corrosion resistance. The results of potentiodynamic polarization measurements demonstrate that Si-DLC coating deposited by PBII exhibits the highest corrosion resistance in an aqueous 0.05 M NaCl solution. Although Ti layer is helpful in increasing adhesion between DLC coating and AZ91 substrate, it also influences adversely corrosion protection. The ozone treatment of the magnesium alloy's surface before the formation of coatings has been found to improve both adhesion strength and corrosion resistance.

  10. Digital slip frequency generator and method for determining the desired slip frequency

    DOEpatents

    Klein, Frederick F.

    1989-01-01

    The output frequency of an electric power generator is kept constant with variable rotor speed by automatic adjustment of the excitation slip frequency. The invention features a digital slip frequency generator which provides sine and cosine waveforms from a look-up table, which are combined with real and reactive power output of the power generator.

  11. Frequency Combs

    NASA Astrophysics Data System (ADS)

    Hänsch, Theodor W.; Picqué, Nathalie

    Much of modern research in the field of atomic, molecular, and optical science relies on lasers, which were invented some 50 years ago and perfected in five decades of intense research and development. Today, lasers and photonic technologies impact most fields of science and they have become indispensible in our daily lives. Laser frequency combs were conceived a decade ago as tools for the precision spectroscopy of atomic hydrogen. Through the development of optical frequency comb techniques, technique a setup of the size 1 ×1 m2, good for precision measurements of any frequency, and even commercially available, has replaced the elaborate previous frequency-chain schemes for optical frequency measurements, which only worked for selected frequencies. A true revolution in optical frequency measurements has occurred, paving the way for the creation of all-optical clocks clock with a precision that might approach 10-18. A decade later, frequency combs are now common equipment in all frequency metrology-oriented laboratories. They are also becoming enabling tools for an increasing number of applications, from the calibration of astronomical spectrographs to molecular spectroscopy. This chapter first describes the principle of an optical frequency comb synthesizer. Some of the key technologies to generate such a frequency comb are then presented. Finally, a non-exhaustive overview of the growing applications is given.

  12. Phase separation in NiCrN coatings induced by N2 addition in the gas phase: A way to generate magnetic thin films by reactive sputtering of a non-magnetic NiCr target

    NASA Astrophysics Data System (ADS)

    Luciu, I.; Duday, D.; Choquet, P.; Perigo, E. A.; Michels, A.; Wirtz, T.

    2016-12-01

    Magnetic coatings are used for a lot of applications from data storage in hard discs, spintronics and sensors. Meanwhile, magnetron sputtering is a process largely used in industry for the deposition of thin films. Unfortunately, deposition of magnetic coatings by magnetron sputtering is a difficult task due to the screening effect of the magnetic target lowering the magnetic field strength of the magnet positioned below the target, which is used to generate and trap ions in the vicinity of the target surface to be sputtered. In this work we present an efficient method to obtain soft magnetic thin films by reactive sputtering of a non-magnetic target. The aim is to recover the magnetic properties of Ni after dealloying of Ni and Cr due to the selective reactivity of Cr with the reactive nitrogen species generated during the deposition process. The effects of nitrogen content on the dealloying and DC magnetron sputtering (DCMS) deposition processes are studied here. The different chemical compositions, microstructures and magnetic properties of DCMS thin films obtained by sputtering in reactive gas mixtures with different ratios of Ar/N2 from a non-magnetic Ni-20Cr target have been determined. XPS data indicate that the increase of nitrogen content in the films has a strong influence on the NiCr phase decomposition into Ni and CrN, leading to ferromagnetic coatings due to the Ni phase. XRD results show that the obtained Ni-CrN films consist of a metallic fcc cubic Ni phase mixed with fcc cubic CrN. The lattice parameter decreases with the N2 content and reaches the theoretical value of the pure fcc-Ni, when Cr is mostly removed from the Ni-Cr phase. Dealloying of Cr from a Ni80-Cr20 solid solution is achieved in our experimental conditions and the deposition of Ni ferromagnetic coatings embedding CrN from a non-magnetic target is possible with reactive DC magnetron sputtering.

  13. [Effect of radio frequency discharge plasma on surface properties and biocompatibility of polycaprolactone matrices].

    PubMed

    Bolbasov, E N; Antonova, L V; Matveeva, V G; Novikov, V A; Shesterikov, E V; Bogomolova, N L; Golovkin, A S; Tverdohlebov, S I; Barbarash, O L; Barbarash, L S

    2016-01-01

    Surface modification of bioresorbable polymer material (polycaprolactone, PCL) with abnormal glow discharge, initiated during radio-frequency magnetron sputtering of a hydroxyapatite target was investigated. Plasma treatment resulted in an increase of surface roughness of PCL, crystallite size, the surface free energy and hydrophilicity. Increased treatment time (30, 60, 150 seconds) provoked the polymer surface saturation with the sputtering target ions (calcium, phosphorus). The assessment of plasma exposure of PCL surface on bone marrow multipotent mesenchymal stromal cells behavior (BM MSCs) has been performed. Modification of the polymer surface with the abnormal glow discharge stimulated adhesion and subsequent proliferation of BM MSCs; thus, maximum values were achieved with the surface treatment for 60 s. This type of plasma modification did not affect cell viability (apoptosis, necrosis). Thus, the surface modification with abnormal glow discharge, initiated during radio-frequency magnetron sputtering of a hydroxyapatite target, appear to be a promising method of surface modification of bioresorbable polymer material (PCL) for tissue engineering.

  14. The use of segmented cathodes to determine the spoke current density distribution in high power impulse magnetron sputtering plasmas

    SciTech Connect

    Poolcharuansin, Phitsanu; Estrin, Francis Lockwood; Bradley, James W.

    2015-04-28

    The localized target current density associated with quasi-periodic ionization zones (spokes) has been measured in a high power impulse magnetron sputtering (HiPIMS) discharge using an array of azimuthally separated and electrical isolated probes incorporated into a circular aluminum target. For a particular range of operating conditions (pulse energies up to 2.2 J and argon pressures from 0.2 to 1.9 Pa), strong oscillations in the probe current density are seen with amplitudes up to 52% above a base value. These perturbations, identified as spokes, travel around the discharge above the target in the E×B direction. Using phase information from the angularly separated probes, the spoke drift speeds, angular frequencies, and mode number have been determined. Generally, at low HiPIMS pulse energies E{sub p} < 0.8 J, spokes appear to be chaotic in nature (with random arrival times), however as E{sub p} increases, coherent spokes are observed with velocities between 6.5 and 10 km s{sup −1} and mode numbers m = 3 or above. At E{sub p} > 1.8 J, the plasma becomes spoke-free. The boundaries between chaotic, coherent, and no-spoke regions are weakly dependent on pressure. During each HiPIMS pulse, the spoke velocities increase by about 50%. Such an observation is explained by considering spoke velocities to be determined by the critical ionization velocity, which changes as the plasma composition changes during the pulse. From the shape of individual current density oscillations, it appears that the leading edge of the spoke is associated with a slow increase in local current density to the target and the rear with a more rapid decrease. The measurements show that the discharge current density associated with individual spokes is broadly spread over a wide region of the target.

  15. Influence of high power impulse magnetron sputtering plasma ionization on the microstructure of TiN thin films

    NASA Astrophysics Data System (ADS)

    Ehiasarian, A. P.; Vetushka, A.; Gonzalvo, Y. Aranda; Sáfrán, G.; Székely, L.; Barna, P. B.

    2011-05-01

    HIPIMS (High Power Impulse Magnetron Sputtering) discharge is a new PVD technology for the deposition of high-quality thin films. The deposition flux contains a high degree of metal ionization and nitrogen dissociation. The microstructure of HIPIMS-deposited nitride films is denser compared to conventional sputter technologies. However, the mechanisms acting on the microstructure, texture and properties have not been discussed in detail so far. In this study, the growth of TiN by HIPIMS of Ti in mixed Ar and N2 atmosphere has been investigated. Varying degrees of metal ionization and nitrogen dissociation were produced by increasing the peak discharge current (Id) from 5 to 30 A. The average power was maintained constant by adjusting the frequency. Mass spectrometry measurements of the deposition flux revealed a high content of ionized film-forming species, such as Ti1+, Ti2+ and atomic nitrogen N1+. Ti1+ ions with energies up to 50 eV were detected during the pulse with reducing energy in the pulse-off times. Langmuir probe measurements showed that the peak plasma density during the pulse was 3 × 1016 m-3. Plasma density, and ion flux ratios of N1+: N21+ and Ti1+: Ti0 increased linearly with peak current. The ratios exceeded 1 at 30 A. TiN films deposited by HIPIMS were analyzed by X-ray diffraction, and transmission electron microscopy. At high Id, N1+: N21+> 1 and Ti1+: Ti0> 1 were produced; a strong 002 texture was present and column boundaries in the films were atomically tight. As Id reduced and N1+: N21+ and Ti1+: Ti0 dropped below 1, the film texture switched to strong 111 with a dense structure. At very low Id, porosity between columns developed. The effects of the significant activation of the deposition flux observed in the HIPIMS discharge on the film texture, microstructure, morphology and properties are discussed.

  16. Improvement of adhesion and barrier properties of biomedical stainless steel by deposition of YSZ coatings using RF magnetron sputtering

    SciTech Connect

    Sánchez-Hernández, Z.E.; Domínguez-Crespo, M.A.; Torres-Huerta, A.M.; Onofre-Bustamante, E.; Andraca Adame, J.; Dorantes-Rosales, H.

    2014-05-01

    The AISI 316L stainless steel (SS) has been widely used in both artificial knee and hip joints in biomedical applications. In the present study, yttria stabilized zirconia (YSZ, ZrO{sub 2} + 8% Y{sub 2}O{sub 3}) films were deposited on AISI 316L SS by radio-frequency magnetron sputtering using different power densities (50–250 W) and deposition times (30–120 min) from a YSZ target. The crystallographic orientation and surface morphology were studied using X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The effects of the surface modification on the corrosion performance of AISI 316L SS were evaluated in phosphate buffered saline (PBS) solution using an electrochemical test on both the virgin and coated samples. The YSZ coatings have a (111) preferred orientation during crystal growth along the c-axis for short deposition times (30–60 min), whereas a polycrystalline structure forms during deposition times from 90 to 120 min. The corrosion protective character of the YSZ coatings depends on the crystal size and film thickness. A significant increase in adhesion and corrosion resistance by at least a factor of 46 and a higher breakdown potential were obtained for the deposited coatings at 200 W (120 min). - Highlights: • Well-formed and protective YSZ coatings were achieved on AISI 316L SS substrates. • Films grown at high power and long deposition time have polycrystalline structures. • The crystal size varies from ∼ 5 to 30 nm as both power and deposition time increased. • The differences of corrosion resistance are attributed to internal film structure.

  17. Localized traveling ionization zones and their importance for the high power impulse magnetron sputtering process

    NASA Astrophysics Data System (ADS)

    Maszl, Christian

    2016-09-01

    High power impulse magnetron sputtering (HiPIMS) is a technique to deposit thin films with superior quality. A high ionization degree up to 90% and the natural occurence of high energetic metal ions are the reason why HiPIMS exceeds direct current magnetron sputtering in terms of coating quality. On the other hand HiPIMS suffers from a reduced efficiency, especially if metal films are produced. Therefore, a lot of research is done by experimentalists and theoreticians to clarify the transport mechanisms from target to substrate and to identify the energy source of the energetic metal ions. Magnetron plasmas are prone to a wide range of wave phenomena and instabilities. Especially, during HiPIMS at elevated power/current densities, symmetry breaks and self-organization in the plasma torus are observed. In this scenario localized travelling ionization zones with certain quasi-mode numbers are present which are commonly referred to as spokes. Because of their high rotation speed compared to typical process times of minutes their importance for thin film deposition was underestimated at first. Recent investigations show that spokes have a strong impact on particle transport, are probably the source of the high energetic metal ions and are therefore the essence of HiPIMS plasmas. In this contribution we will describe the current understanding of spokes, discuss implications for thin film synthesis and highlight open questions. This project is supported by the DFG (German Science Foundation) within the framework of the Coordinated Research Center SFB-TR 87 and the Research Department ``Plasmas with Complex Interactions'' at Ruhr-University Bochum.

  18. Tailoring of antibacterial Ag nanostructures on TiO2 nanotube layers by magnetron sputtering.

    PubMed

    Uhm, Soo-Hyuk; Song, Doo-Hoon; Kwon, Jae-Sung; Lee, Sang-Bae; Han, Jeon-Geon; Kim, Kyoung-Nam

    2014-04-01

    To reduce the incidence of postsurgical bacterial infection that may cause implantation failure at the implant-bone interface, surface treatment of titanium implants with antibiotic materials such as silver (Ag) has been proposed. The purpose of this work was to create TiO2 nanotubes using plasma electrolytic oxidation (PEO), followed by formation of an antibacterial Ag nanostructure coating on the TiO2 nanotube layer using a magnetron sputtering system. PEO was performed on commercially pure Ti sheets. The Ag nanostructure was added onto the resulting TiO2 nanotube using magnetron sputtering at varying deposition rates. Field emission scanning electron microscopy and transmission electron microscopy were used to characterize the surface, and Ag content on the TiO2 nanotube layer was analyzed by X-ray diffraction and X-ray photoelectron spectroscopy. Scanning probe microscopy for surface roughness and contact angle measurement were used to indirectly confirm enhanced TiO2 nanotube hydrophilicity. Antibacterial activity of Ag ions in solution was determined by inductively coupled plasma mass spectrometry and antibacterial testing against Staphylococcus aureus (S. aureus). In vitro, TiO2 nanotubes coated with sputtered Ag resulted in significantly reduced S. aureus. Cell viability assays showed no toxicity for the lowest sputtering time group in the osteoblastic cell line MC3T3-E1. These results suggest that a multinanostructured layer with a biocompatible TiO2 nanotube and antimicrobial Ag coating is a promising biomaterial that can be tailored with magnetron sputtering for optimal performance.

  19. Surface functionalization of nanostructured LaB6-coated Poly Trilobal fabric by magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Wu, Yan; Zhang, Lin; Min, Guanghui; Yu, Huashun; Gao, Binghuan; Liu, Huihui; Xing, Shilong; Pang, Tao

    2016-10-01

    Nanostructured LaB6 films were deposited on flexible Poly Trilobal substrates (PET textiles) through direct current magnetron sputtering in order to broaden its applications and realize surface functionalization of polyester fabrics. Characterizations and performances were investigated by employing a scanning electron microscope (SEM), Fourier transformation infrared spectroscopy (FT-IR) and ultraviolet-visible (UV-vis) spectrophotometer. Ultraviolet Protection Factor (UPF) conducted by the integral conversion was employed to measure the ultraviolet protection ability. As expected, the growth of LaB6 film depending on the pressure variation enhanced UV-blocking ability (UPF rating at 30.17) and absorption intensity of the textiles.

  20. Spectroscopic imaging of self-organization in high power impulse magnetron sputtering plasmas

    SciTech Connect

    Centre for Quantum Technologies, National University of Singapore, 3 Science Drive 2, 117543 Singapore, Singapore; Andersson, Joakim; Ni, Pavel; Anders, Andre

    2013-07-17

    Excitation and ionization conditions in traveling ionization zones of high power impulse magnetron sputtering plasmas were investigated using fast camera imaging through interference filters. The images, taken in end-on and side on views using light of selected gas and target atom and ion spectral lines, suggest that ionization zones are regions of enhanced densities of electrons, and excited atoms and ions. Excited atoms and ions of the target material (Al) are strongly concentrated near the target surface. Images from the highest excitation energies exhibit the most localized regions, suggesting localized Ohmic heating consistent with double layer formation.