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Sample records for crossed-field diode sputtering

  1. Thin film deposition by electric and magnetic crossed-field diode sputtering. [Patent application

    DOEpatents

    Welch, K.M.

    1975-04-04

    Applying a coating of titanium nitride to a klystron window by means of a cross-field diode sputtering array is described. The array is comprised of a cohesive group of numerous small hollow electrically conducting cylinders and is mounted so that the open ends of the cylinders on one side of the group are adjacent to a titanium cathode plate. The workpiece is mounted so as to face the open ends of the other side of the group. A magnetic field is applied to the array so as to be coaxial with the cylinders and a potential is applied across the cylinders and the cathode plate, the cylinders as an anode being positive with respect to the cathode plate. The cylinders, the cathode plate, and the workpiece are situated in an atmosphere of nitrogen which becomes ionized such as by field emission because of the electric field between the cylinders and cathode plate, thereby establishing an anode-cathode discharge that results in sputtering of the titanium plate. The sputtered titanium coats the workpiece and chemically combines with the nitrogen to form a titanium nitride coating on the workpiece. Gas pressure, gas mixtures, cathode material composition, voltages applied to the cathode and anode, the magnetic field, cathode, anode and workpiece spacing, and the aspect ratio (ratio of length to inner diameter) of the anode cylinders, all may be controlled to provide consistent optimum thin film coatings of various compositions and thickness. Another facet of the disclosure is the coating of microwave components per se with titanium nitride to reduce multifactoring under operating conditions of the components.

  2. Thin film deposition by electric and magnetic crossed-field diode sputtering

    DOEpatents

    Welch, Kimo M.

    1977-01-01

    Applying a thin film coating to the surface of a workpiece, in particular, applying a coating of titanium nitride to a klystron window by means of a crossed-field diode sputtering array. The array is comprised of a cohesive group of numerous small hollow electrically conducting cylinders and is mounted so that the open ends of the cylinders on one side of the group are adjacent a titanium cathode plate. The workpiece is mounted so as to face the open ends of the other side of the group. A magnetic field is applied to the array so as to be coaxial with the cylinders and a potential is applied across the cylinders and the cathode plate, the cylinders as an anode being positive with respect to the cathode plate. The cylinders, the cathode plate and the workpiece are situated in an atmosphere of nitrogen which becomes ionized such as by field emission because of the electric field between the cylinders and cathode plate, thereby establishing an anode-cathode discharge that results in sputtering of the titanium plate. The sputtered titanium coats the workpiece and chemically combines with the nitrogen to form a titanium nitride coating on the workpiece. Gas pressure, gas mixtures, cathode material composition, voltages applied to the cathode and anode, the magnetic field, cathode, anode and workpiece spacing, and the aspect ratio (ratio of length to inner diameter) of the anode cylinders, all may be controlled to provide consistent optimum thin film coatings of various compositions and thicknesses. Another facet of the disclosure is the coating of microwave components per se with titanium nitride to reduce multipactoring under operating conditions of the components.

  3. Thin film deposition by electric and magnetic crossed-field diode sputtering

    DOEpatents

    Welch, Kimo M.

    1980-01-01

    Applying a thin film coating to the surface of a workpiece, in particular, applying a coating of titanium nitride to a klystron window by means of a crossed-field diode sputtering array. The array is comprised of a cohesive group of numerous small hollow electrically conducting cylinders and is mounted so that the open ends of the cylinders on one side of the group are adjacent a titanium cathode plate. The workpiece is mounted so as to face the open ends of the other side of the group. A magnetic field is applied to the array so as to be coaxial with the cylinders and a potential is applied across the cylinders and the cathode plate, the cylinders as an anode being positive with respect to the cathode plate. The cylinders, the cathode plate and the workpiece are situated in an atmosphere of nitrogen which becomes ionized such as by field emission because of the electric field between the cylinders and cathode plate, thereby establishing an anode-cathode discharge that results in sputtering of the titanium plate. The sputtered titanium coats the workpiece and chemically combines with the nitrogen to form a titanium nitride coating on the workpiece. Gas pressure, gas mixtures, cathode material composition, voltages applied to the cathode and anode, the magnetic field, cathode, anode and workpiece spacing, and the aspect ratio (ratio of length to inner diameter) of the anode cylinders, all may be controlled to provide consistent optimum thin film coatings of various compositions and thicknesses. Another facet of the disclosure is the coating of microwave components per se with titanium nitride to reduce multipactoring under operating conditions of the components.

  4. Role of ions in a crossed-field diode.

    PubMed

    Lau, Y Y; Luginsland, J W; Cartwright, K L; Haworth, M D

    2007-01-05

    The effect of ions in a magnetically insulated crossed-field gap is studied using a single particle orbit model, shear flow model, and particle-in-cell simulation. It is found that, in general, the presence of ions in a crossed-field gap always increases the electrons' excursion toward the anode region, regardless of the location of the ions. Thus, the rate at which the electrons migrate toward the anode, which is a measure of the diode closure rate, is related to the rate at which ions are introduced into the crossed-field gap. This anode migration of electrons is unrelated to crossed-field ambipolar diffusion. The implications of these findings are explored, such as pulse shortening in relativistic magnetrons and bipolar flows in pulsed-power systems.

  5. Role of Ions in a Crossed-Field Diode

    SciTech Connect

    Lau, Y. Y.; Luginsland, J. W.; Cartwright, K. L.; Haworth, M. D.

    2007-01-05

    The effect of ions in a magnetically insulated crossed-field gap is studied using a single particle orbit model, shear flow model, and particle-in-cell simulation. It is found that, in general, the presence of ions in a crossed-field gap always increases the electrons' excursion toward the anode region, regardless of the location of the ions. Thus, the rate at which the electrons migrate toward the anode, which is a measure of the diode closure rate, is related to the rate at which ions are introduced into the crossed-field gap. This anode migration of electrons is unrelated to crossed-field ambipolar diffusion. The implications of these findings are explored, such as pulse shortening in relativistic magnetrons and bipolar flows in pulsed-power systems.

  6. Measurement and interpretation of current transmission in a crossed-field diode below cutoff

    SciTech Connect

    Vanderberg, B.H.; Eninger, J.E.

    1997-02-01

    Measurements on the current-voltage-magnetic field characteristics of a space-charge-limited cylindrical cross-field diode below cutoff are presented. The measured current is found to be lower than predicted by simple cold-fluid theory. This reduction combined with observed oscillations in the current can be explained by secondary electron emission from the anode, leading to an increase of space charge in the diode. {copyright} {ital 1997 American Institute of Physics.}

  7. Measurement and interpretation of current transmission in a crossed-field diode below cutoff

    NASA Astrophysics Data System (ADS)

    Vanderberg, Bo H.; Eninger, Jan E.

    1997-02-01

    Measurements on the current-voltage-magnetic field characteristics of a space-charge-limited cylindrical cross-field diode below cutoff are presented. The measured current is found to be lower than predicted by simple cold-fluid theory. This reduction combined with observed oscillations in the current can be explained by secondary electron emission from the anode, leading to an increase of space charge in the diode.

  8. Modeling the effects of anode secondary electron emission on transmitted current in crossed-field diodes

    NASA Astrophysics Data System (ADS)

    Gopinath, Venkatesh; Vanderberg, Bo

    1996-11-01

    Recent experimental measurements of transmitted current in a crossed-field switch by Vanderberg and Eninger ( B. H. Vanderberg and J. E. Eninger, ``Space-charge limited current cut-off in crossed fields,'' presented at IEEE ICOPS'95, Madison, Wi. ) have shown that the measured values of transmitted current are significantly smaller than the theoretically predicted limit. The experiments also showed larger decrease in transmitted current for higher magnetic fields, implying an effect due to the higher angle of incidence of incident electrons (i.e., at values of B closer to B_H). Studies by Verboncoeur and Birdsall ( J. P. Verboncoeur and C. K. Birdsall. ``Rapid current transition in a crossed-field diode,'' Phys. Plasmas 3) 3, March 1996. have shown that even small amount ( < 1%) of over injection in a crossed-field diode near cut-off led to substantial decrease in transmitted current. In our current work, we show that the same effect can be triggered by the presence of secondary electron emission from the anode. This study models the dependence of emission upon incident electron angle and energy. Since the yield of secondary electrons increases with incident angle, this model follows the experimental results as B approaches B_Hull accurately. This work was supported in part by ONR under grant FD-N00014-90-J-1198

  9. The Effect of Secondary Emission Cathode Parameters on (Near-) Brillouin Flow in Crossed-Field Diodes

    NASA Astrophysics Data System (ADS)

    Fichtl, Christopher

    2005-10-01

    The initial velocity that an electron has from the cathode can change the magnetic field needed to insulate a crossed-field diode. For a secondary emitting cathode the distribution of emitted electron velocities depends on the velocity distribution of electrons returning to the cathode. We have studied the evolution of the Brillouin hub in a crossed-field diode in self-consistent 1d electromagnetic Particle-in-Cell (PIC) code with thermal emission and a secondary emission model by Vaughan. The baseline simulations have thermal emission with 0.1 eV of temperature; this is compared to simulations that have both secondary emission and thermal emission. The fraction of reflected and back scattered primaries is varied to induce perturbations in the Brillouin hub. The temperature of the true secondaries is conveniently set to the thermal emission temperature of 0.1 eV. It is found that relatively few (˜10%) reflected and back scattered primaries allow the Brillouin hub to expand further across the diode as compared to the thermal emission cathode.

  10. Sputtering

    NASA Technical Reports Server (NTRS)

    Spalvins, T.

    1976-01-01

    The potential of using the sputtering process as a deposition technique is reviewed; however, the manufacturing and sputter etching aspects are also discussed. The basic mechanism for dc and rf sputtering is described. Sputter deposition is presented in terms of the unique advantageous features it offers such as versatility, momentum transfer, stoichiometry, sputter etching, target geometry (coating and complex surfaces), precise controls, flexibility, ecology, and sputtering rates. Sputtered film characteristics, such as strong adherence and coherence and film morphology, are briefly evaluated in terms of varying the sputtering parameters. Also discussed are some of the specific industrial areas which are turning to sputter deposition techniques.

  11. Fabrication and characterization of sputtered Cu2O:N/c-Si heterojunction diode

    NASA Astrophysics Data System (ADS)

    Takiguchi, Yuki; Takei, Yutaro; Nakada, Kazuyoshi; Miyajima, Shinsuke

    2017-08-01

    Nitrogen doped cuprous oxide (Cu2O:N) deposited by reactive sputtering was applied to a crystalline silicon (c-Si) based heterojunction diode. The current density-voltage (J-V) characteristics of the fabricated diode showed rectifying characteristics with a high rectifying ratio of 105 at ±1 V. The capacitance-voltage measurements revealed the existence of a large conduction band offset and a small valence band offset at the Cu2O:N/c-Si interface, which implies that Cu2O:N is a suitable material for a hole selective emitter layer in n-type c-Si based heterojunction solar cells. Detailed analysis of the temperature dependent J-V characteristics showed that the diode current was limited by interface recombination originated from Fermi level pinning at the Cu2O:N/c-Si interface.

  12. Effect of positively charged particles on sputtering damage of organic electro-luminescent diodes with Mg:Ag alloy electrodes fabricated by facing target sputtering

    NASA Astrophysics Data System (ADS)

    Suemori, Kouji; Hoshino, Satoshi; Ibaraki, Nobuki; Kamata, Toshihide

    2017-04-01

    We investigated the influence of the positively charged particles generated during sputtering on the performances of organic light-emitting diodes (OLEDs) with Mg:Ag alloy electrodes fabricated by sputtering. The number of positively charged particles increased by several orders of magnitude when the target current was increased from 0.1 A to 2.5 A. When a high target current was used, many positively charged particles with energies higher than the bond energy of single C-C bonds, which are typically found in organic molecules, were generated. In this situation, we observed serious OLED performance degradation. On the other hand, when a low target current was used, OLED performance degradation was not observed when the number of positively charged particles colliding with the organic underlayer increased. We concluded that sputtering damage caused by positively charged particles can be avoided by using a low target current.

  13. Time resolved tunable diode laser absoption spectroscopy of dual High Power Impulse Magnetron Sputtering discharges

    NASA Astrophysics Data System (ADS)

    Do, Hoang Tung; Stranak, Vitezslav; Hippler, Rainer

    2014-08-01

    Time-resolved measurements have been performed during dual High Power Impulse Magnetron Sputtering (dual-HiPIMS) with two cathodes in a closed magnetic field configuration. The dual-HiPIMS system, operated at a repetition frequency f = 100 Hz and duty cycle of 1 %, was equipped with two different metallic targets (Ti, Cu). The effect of a delay between subsequent pulses on argon excited atom density and temperature was investigated by means of tunable diode laser absorption spectroscopy. It is shown that the peak densities of pulses vary strongly with the delay. We observed an enhancement of metastable density due to pre-ionization effect but more effective than that is the contribution of metal atoms which have smaller ionization energy compare to that of buffer gas atom. Associate with the enhancement of density, the temporal variation of metastable atom temperature in the Cu pulse also transforms from those of low current pulse into the high current one.

  14. Electrical characterization of Mo/n-GaAs/In Schottky diodes fabricated by rf sputtering

    SciTech Connect

    Singh, A.; Velasquez, L.

    1996-07-01

    Mo Schottky contacts to n-GaAs were fabricated by deposition of Mo on the front side of (100) n-GaAs by rf sputtering, using an rf power of 200 watts with argon pressure of 6.5{times}10{sup {minus}3} Torr. Back ohmic contacts to n-GaAs were prepared by Sputter deposition of In using an rf power of 50 watts, followed by a 3.5 hour anneal in Ar atmosphere at 390{degree}C. The forward I{endash}V characteristics for the Mo/n-GaAs/In Schottky diode were non ideal over the temperature range 160{endash}350 K. The analysis of the forward I{endash}V/T data indicated that the forward current transport was controlled largely by generation-recombination (GR) in the depletion region and to a lesser extent by thermionic emission (TE) over the temperature range 260{endash}350 K. From the temperature variation of the TE reverse saturation current, the values of (1.04{plus_minus}0.02) V and (2.1{plus_minus}0.5){times}10{sup 6} Acm{sup {minus}2}K{sup {minus}2} for the zero bias zero temperature barrier height ({phi}{sub 0}) and the effective Richardson constant ({ital A}{sub eff}), respectively, were obtained. A value of ({minus}1.1{plus_minus}0.1) mV/K for the temperature coefficient ({beta}) of the barrier height was required to justify such a high value for {ital A}{sub eff}. A similar value of {beta} is supported by our C-V data in the same Mo/n-GaAs/In Schottky diode. {copyright} {ital 1996 American Institute of Physics.}

  15. Plasma damage-free sputtering of indium tin oxide cathode layers for top-emitting organic light-emitting diodes

    SciTech Connect

    Kim, Han-Ki; Kim, D.-G.; Lee, K.-S.; Huh, M.-S.; Jeong, S.H.; Kim, K.I.; Seong, Tae-Yeon

    2005-05-02

    We report on plasma damage-free sputtering of an indium tin oxide (ITO) cathode layer, which was grown by a mirror shape target sputtering (MSTS) technique, for use in top-emitting organic light-emitting diodes (TOLEDs). It is shown that OLEDs with ITO cathodes deposited by MSTS show much lower leakage current (9.2x10{sup -5} mA/cm{sup 2}) at reverse bias of -6 V as compared to that (1x10{sup -1}-10{sup -2} mA/cm{sup 2} at -6 V) of OLEDs with ITO cathodes grown by conventional dc magnetron sputtering. Based on high-resolution electron microcopy, x-ray diffraction, and scanning electron microscopy results, we describe a possible mechanism by which plasma damage-free ITO films are grown and their application for TOLEDs.

  16. Fabrication of full-color InGaN-based light-emitting diodes on amorphous substrates by pulsed sputtering

    NASA Astrophysics Data System (ADS)

    Shon, Jeong Woo; Ohta, Jitsuo; Ueno, Kohei; Kobayashi, Atsushi; Fujioka, Hiroshi

    2014-06-01

    InGaN-based light-emitting diodes (LEDs) have been widely accepted as highly efficient light sources capable of replacing incandescent bulbs. However, applications of InGaN LEDs are limited to small devices because their fabrication process involves expensive epitaxial growth of InGaN by metalorganic vapor phase epitaxy on single-crystal wafers. If we can utilize a low-cost epitaxial growth process, such as sputtering on large-area substrates, we can fabricate large-area InGaN light-emitting displays. Here, we report the growth of GaN (0001) and InGaN (0001) films on amorphous SiO2 by pulsed sputtering deposition. We found that using multilayer graphene buffer layers allows the growth of highly c-axis-oriented GaN films even on amorphous substrates. We fabricated red, green, and blue InGaN LEDs and confirmed their successful operation. This successful fabrication of full-color InGaN LEDs on amorphous substrates by sputtering indicates that the technique is quite promising for future large-area light-emitting displays on amorphous substrates.

  17. Fabrication of full-color InGaN-based light-emitting diodes on amorphous substrates by pulsed sputtering.

    PubMed

    Shon, Jeong Woo; Ohta, Jitsuo; Ueno, Kohei; Kobayashi, Atsushi; Fujioka, Hiroshi

    2014-06-23

    InGaN-based light-emitting diodes (LEDs) have been widely accepted as highly efficient light sources capable of replacing incandescent bulbs. However, applications of InGaN LEDs are limited to small devices because their fabrication process involves expensive epitaxial growth of InGaN by metalorganic vapor phase epitaxy on single-crystal wafers. If we can utilize a low-cost epitaxial growth process, such as sputtering on large-area substrates, we can fabricate large-area InGaN light-emitting displays. Here, we report the growth of GaN (0001) and InGaN (0001) films on amorphous SiO2 by pulsed sputtering deposition. We found that using multilayer graphene buffer layers allows the growth of highly c-axis-oriented GaN films even on amorphous substrates. We fabricated red, green, and blue InGaN LEDs and confirmed their successful operation. This successful fabrication of full-color InGaN LEDs on amorphous substrates by sputtering indicates that the technique is quite promising for future large-area light-emitting displays on amorphous substrates.

  18. Improved output power of GaN-based ultraviolet light-emitting diodes with sputtered AlN nucleation layer

    NASA Astrophysics Data System (ADS)

    Chiu, C. H.; Lin, Y. W.; Tsai, M. T.; Lin, B. C.; Li, Z. Y.; Tu, P. M.; Huang, S. C.; Hsu, Earl; Uen, W. Y.; Lee, W. I.; Kuo, H. C.

    2015-03-01

    In this work, the ultraviolet light-emitting diodes (UV-LEDs) at 380 nm were grown on patterned sapphire substrate (PSS) by atmospheric pressure metal organic chemical vapor deposition (AP-MOCVD). A sputtered AlN nucleation layer was utilized on the PSS to enhance the quality of the epitaxial layer. By using high-resolution X-ray diffraction, the full-width at half-maximum of the rocking curve shows that the UV-LEDs with sputtered AlN nucleation layer had better crystalline quality when compared to conventional GaN nucleation samples. From the scanning electron microscope (SEM) and transmission electron microscopy (TEM) images, it can be observed that the tip and sidewall portion of the pattern was smooth using the sputtered AlN nucleation layer. The threading dislocation densities (TDDs) are reduced from 6×107 cm-2 to 2.5×107 cm-2 at the interface between the u-GaN layers for conventional and AlN PSS devices, respectively. As a result, a much higher light output power was achieved. The light output power at an injection current of 20 mA was enhanced by 30%. Further photoluminescence (PL) measurement and numerical simulation confirm that this increase of output power can be attributed to the improvement of material quality and light extraction.

  19. Improved performance of GaN based light emitting diodes with ex-situ sputtered AlN nucleation layers

    SciTech Connect

    Chen, Shuo-Wei; Li, Heng; Lu, Tien-Chang

    2016-04-15

    The crystal quality, electrical and optical properties of GaN based light emitting diodes (LEDs) with ex-situ sputtered physical vapor deposition (PVD) aluminum nitride (AlN) nucleation layers were investigated. It was found that the crystal quality in terms of defect density and x-ray diffraction linewidth was greatly improved in comparison to LEDs with in-situ low temperature GaN nucleation layer. The light output power was 3.7% increased and the reverse bias voltage of leakage current was twice on LEDs with ex-situ PVD AlN nucleation layers. However, larger compressive strain was discovered in LEDs with ex-situ PVD AlN nucleation layers. The study shows the potential and constrain in applying ex-situ PVD AlN nucleation layers to fabricate high quality GaN crystals in various optoelectronics.

  20. Improved performance of GaN based light emitting diodes with ex-situ sputtered AlN nucleation layers

    NASA Astrophysics Data System (ADS)

    Chen, Shuo-Wei; Li, Heng; Lu, Tien-Chang

    2016-04-01

    The crystal quality, electrical and optical properties of GaN based light emitting diodes (LEDs) with ex-situ sputtered physical vapor deposition (PVD) aluminum nitride (AlN) nucleation layers were investigated. It was found that the crystal quality in terms of defect density and x-ray diffraction linewidth was greatly improved in comparison to LEDs with in-situ low temperature GaN nucleation layer. The light output power was 3.7% increased and the reverse bias voltage of leakage current was twice on LEDs with ex-situ PVD AlN nucleation layers. However, larger compressive strain was discovered in LEDs with ex-situ PVD AlN nucleation layers. The study shows the potential and constrain in applying ex-situ PVD AlN nucleation layers to fabricate high quality GaN crystals in various optoelectronics.

  1. Characterization of energetic and thermalized sputtered atoms in pulsed plasma using time-resolved tunable diode-laser induced fluorescence

    SciTech Connect

    Desecures, M.; Poucques, L. de; Easwarakhanthan, T.; Bougdira, J.

    2014-11-03

    In this work, a time-resolved tunable diode-laser (DL) induced fluorescence (TR-TDLIF) method calibrated by absorption spectroscopy has been developed in order to determine atom and flux velocity distribution functions (AVDF and FVDF) of the energetic and the thermalized atoms in pulsed plasmas. The experimental set-up includes a low-frequency (∼3 Hz) and high spectral-resolution DL (∼0.005 pm), a fast rise-time pulse generator, and a high power impulse magnetron sputtering (HiPIMS) system. The induced TR-TDLIF signal is recorded every 0.5 μs with a digital oscilloscope of a second-long trace. The technique is illustrated with determining the AVDF and the FVDF of a metastable state of the sputtered neutral tungsten atoms in the HiPIMS post-discharge. Gaussian functions describing the population of the four W isotopes were used to fit the measured TR-TDLIF signal. These distribution functions provide insight into transition from the energetic to thermalized regimes from the discharge onset. This technique may be extended with appropriate DLs to probe any species with rapidly changing AVDF and FVDF in pulsed and strongly oscillating plasmas.

  2. Transparent indium zinc oxide top cathode prepared by plasma damage-free sputtering for top-emitting organic light-emitting diodes

    SciTech Connect

    Kim, Han-Ki; Lee, Kyu-Sung; Kwon, J.H.

    2006-01-02

    We report on plasma damage-free sputtering of an indium zinc oxide (IZO) top cathode layer for top-emitting organic light-emitting diodes (TOLEDs) by using a box cathode sputtering (BCS) technique. A sheet resistance of 42.6 {omega}/cm and average transmittance above 88% in visible range were obtained even in IZO layers deposited by BCS at room temperature. The TOLED with the IZO top cathode layer shows electrical characteristics and lifetime comparable to a TOLED with only thermally evaporated Mg-Ag cathode. In particular, it is shown that the TOLED with the IZO top cathode film shows very low leakage current density of 1x10{sup -5} mA cm{sup 2} at reverse bias of -6 V. This suggests that there is no plasma damage caused by the bombardment of energetic particles during IZO sputtering using the BCS system.

  3. Study on MoO{sub 3-x} films deposited by reactive sputtering for organic light-emitting diodes

    SciTech Connect

    Oka, Nobuto; Watanabe, Hiroki; Sato, Yasushi; Yamaguchi, Hiroshi; Ito, Norihiro; Tsuji, Hiroya; Shigesato, Yuzo

    2010-07-15

    The authors investigate the role of reduced molybdenum trioxide [MoO{sub 3-x} (x{<=}1)] films in organic light-emitting diodes, particularly from the viewpoint of the oxidation state of Mo. MoO{sub 3-x} films were deposited by reactive sputtering under a mixture of argon (Ar) and oxygen (O{sub 2}). The O{sub 2} gas-flow ratio (GFR) [O{sub 2}/(Ar+O{sub 2})] was adjusted between 10% and 100%. Mo with six, five, and four valence electrons was detected in MoO{sub 3-x} film deposited with an O{sub 2} GFR of 10% and 12.5%, whereas, under higher O{sub 2} GFRs, only six valence electrons for Mo in the MoO{sub 3-x} film were detected. N,N{sup '}-di(1-naphthyl)-N,N{sup '}-diphenylbenzidine ({alpha}-NPD) layer, hole-transport material, were deposited over the MoO{sub 3-x} layer by subsequent vacuum evaporation. At the {alpha}-NPD/MoO{sub 3-x} interface, it was found that {alpha}-NPD cations were generated and that MoO{sub 3-x} was reduced, which provided evidence of charge transfer across the interface by Raman spectroscopy and x-ray photoelectron spectroscopy.

  4. Effects of GaN/AlGaN/Sputtered AlN nucleation layers on performance of GaN-based ultraviolet light-emitting diodes

    PubMed Central

    Hu, Hongpo; Zhou, Shengjun; Liu, Xingtong; Gao, Yilin; Gui, Chengqun; Liu, Sheng

    2017-01-01

    We report on the demonstration of GaN-based ultraviolet light-emitting diodes (UV LEDs) emitting at 375 nm grown on patterned sapphire substrate (PSS) with in-situ low temperature GaN/AlGaN nucleation layers (NLs) and ex-situ sputtered AlN NL. The threading dislocation (TD) densities in GaN-based UV LEDs with GaN/AlGaN/sputtered AlN NLs were determined by high-resolution X-ray diffraction (XRD) and cross-sectional transmission electron microscopy (TEM), which revealed that the TD density in UV LED with AlGaN NL was the highest, whereas that in UV LED with sputtered AlN NL was the lowest. The light output power (LOP) of UV LED with AlGaN NL was 18.2% higher than that of UV LED with GaN NL owing to a decrease in the absorption of 375 nm UV light in the AlGaN NL with a larger bandgap. Using a sputtered AlN NL instead of the AlGaN NL, the LOP of UV LED was further enhanced by 11.3%, which is attributed to reduced TD density in InGaN/AlInGaN active region. In the sputtered AlN thickness range of 10–25 nm, the LOP of UV LED with 15-nm-thick sputtered AlN NL was the highest, revealing that optimum thickness of the sputtered AlN NL is around 15 nm. PMID:28294166

  5. Effects of GaN/AlGaN/Sputtered AlN nucleation layers on performance of GaN-based ultraviolet light-emitting diodes

    NASA Astrophysics Data System (ADS)

    Hu, Hongpo; Zhou, Shengjun; Liu, Xingtong; Gao, Yilin; Gui, Chengqun; Liu, Sheng

    2017-03-01

    We report on the demonstration of GaN-based ultraviolet light-emitting diodes (UV LEDs) emitting at 375 nm grown on patterned sapphire substrate (PSS) with in-situ low temperature GaN/AlGaN nucleation layers (NLs) and ex-situ sputtered AlN NL. The threading dislocation (TD) densities in GaN-based UV LEDs with GaN/AlGaN/sputtered AlN NLs were determined by high-resolution X-ray diffraction (XRD) and cross-sectional transmission electron microscopy (TEM), which revealed that the TD density in UV LED with AlGaN NL was the highest, whereas that in UV LED with sputtered AlN NL was the lowest. The light output power (LOP) of UV LED with AlGaN NL was 18.2% higher than that of UV LED with GaN NL owing to a decrease in the absorption of 375 nm UV light in the AlGaN NL with a larger bandgap. Using a sputtered AlN NL instead of the AlGaN NL, the LOP of UV LED was further enhanced by 11.3%, which is attributed to reduced TD density in InGaN/AlInGaN active region. In the sputtered AlN thickness range of 10-25 nm, the LOP of UV LED with 15-nm-thick sputtered AlN NL was the highest, revealing that optimum thickness of the sputtered AlN NL is around 15 nm.

  6. Performance of RF sputtered p-Si/n-ZnO nanoparticle thin film heterojunction diodes in high temperature environment

    NASA Astrophysics Data System (ADS)

    Singh, Satyendra Kumar; Hazra, Purnima

    2017-04-01

    In this article, temperature-dependent current-voltage characteristics of n-ZnO/p-Si nanoparticle thin film heterojunction diode grown by RF sputtering technique are analyzed in the temperature range of 300-433 k to investigate the performance of the device in high temperature environment. The microstructural, morphological, optical and temptrature dependent electrical properties of as-grown nanoparticle thin film were characterized by X-ray diffractometer (XRD), atomic force microscopy (AFM), field emmision scanning electron microscopy (FESEM), energy-dispersive X-ray spectroscopy (EDX), variable angle ellipsometer and semiconductor device analyzer. XRD spectra of as-grown ZnO films are exhibited that highly c-axis oriented ZnO nanostructures are grown on p- Si<100> substrate whereas AFM and FESEM images confirm the homogeneous deposition of ZnO nanoparticles on surface of Si substratewith minimum roughness.The optical propertiesof as-grown ZnO nanoparticles have been measured in the spectral range of 300-800 nm using variable angle ellipsometer.To measure electrical parameters of the device prototype in the temperature range of room temperature (300 K) to 433 K, large area ohmic contacts were fabricated on both side of the ZnO/Si heterostructure. From the current-voltage charcteristics of ZnO/Si heterojunction device, it is observed that the device exhibits rectifing nature at room temperature. However, with increase in temperature, reverse saturation current and barrier height are found to increase, whereas ideality factor is started decreasing. This phenomenon confirms that barrier inhomogeneities are present at the interface of ZnO/Si heterojunction, as a result of lattice constant and thermal coefficient mismatch between Si and ZnO. Therefore, a modified value of Richardson constant [33.06 Acm-2K-2] has been extracted from the temperature-dependent electrical characteristics after assuming the Gaussian distribution of special barrier height inhomogeneities

  7. Improvement in luminance efficiency of organic light emitting diodes by suppression of secondary electron bombardment of substrate during sputter deposition of top electrode films

    NASA Astrophysics Data System (ADS)

    Hamaguchi, Daichi; Kobayashi, Shin-ichi; Uchida, Takayuki; Sawada, Yutaka; Lei, Hao; Hoshi, Yoichi

    2016-10-01

    In this study, we investigated the degradation mechanisms of the luminance performance of organic light-emitting diodes (OLEDs) when their top electrode films were deposited by sputter deposition process. During the sputter deposition of the top electrode films, the suppression of the incidence of high-energy electrons on the substrate was attempted using various methods. As a result, we found that during electrode deposition, the incidence of the high-energy secondary electrons, which were emitted from the target surface, on the substrate was the main cause of the significant degradation of the luminance performance. It was also found that the application of a magnetic field by setting permanent magnets near the substrate holder and the insertion of a shield plate near the target cathode were effective in suppressing the incidence of secondary electrons on the substrate.

  8. Al/AlN/InP Metal-Insulator-Semiconductor-Diode Characteristics with Amorphous AlN Films Deposited by Electron-Cyclotron-Resonance Sputtering

    NASA Astrophysics Data System (ADS)

    Saito, Kunio; Ono, Toshiro; Shimada, Masaru; Shigekawa, Naoteru; Enoki, Takatomo

    2005-01-01

    Amorphous AlN films deposited by sputtering using electron cyclotron resonance (ECR) plasma were used to form AlN/n-InP metal-insulator-semiconductor diodes. The AlN films were deposited without substrate heating. Capacitance-voltage (C-V) measurements showed a small hysteresis window of ˜35 mV for a 2-nm-thick AlN film, and frequency dispersion was much improved by post-deposition annealing at 200°C in an H2 gas atmosphere. We estimated the interface-trap density to be 3× 1012 cm-2eV-1 by comparing 10-kHz and 1-MHz C-V curves. Small leakage currents of less than 2 mA/cm2 at a bias voltage of 1 V were obtained for the 2-nm-thick film. To clarify the effect of the deposition methods, AlN films were deposited by conventional magnetron sputtering. ECR sputtering provided better C-V and current-voltage characteristics than magnetron sputtering for as-deposited AlN films, showing that good metal-insulator-semiconductor (MIS) properties arise because of the suitable deposition method and the good combination of materials. An analysis of surface atoms on the InP substrate by secondary ion mass spectrometry showed a large oxygen concentration on the order of 1022 cm-3, which is not preferable for MIS diode properties. Surface cleaning using dilute HF reduced oxygen and carbon concentrations to less than half.

  9. Blue electroluminescence from Sb-ZnO/Cd-ZnO/Ga-ZnO heterojunction diode fabricated by dual ion beam sputtering.

    PubMed

    Pandey, Sushil Kumar; Awasthi, Vishnu; Verma, Shruti; Mukherjee, Shaibal

    2014-12-15

    p-type Sb-doped ZnO/i-CdZnO/n-type Ga-doped ZnO was grown by dual ion beam sputtering deposition system. Current-voltage characteristics of the heterojunction showed a diode-like rectifying behavior with a turn-on voltage of ~5 V. The diode yielded blue electroluminescence emissions at around 446 nm in forward biased condition at room temperature. The emission intensity increased with the increase of the injection current. A red shifting of the emission peak position was observed with the increment of ambient temperature, indicating a change of band gap of the CdZnO active layer with temperature in low-temperature measurement.

  10. Effect of nitrogen doping on the structural, optical and electrical properties of indium tin oxide films prepared by magnetron sputtering for gallium nitride light emitting diodes

    NASA Astrophysics Data System (ADS)

    Tian, Lifei; Cheng, Guoan; Wang, Hougong; Wu, Yulong; Zheng, Ruiting; Ding, Peijun

    2017-01-01

    The indium tin oxide (ITO) films are prepared by the direct current magnetron sputtering technology with an ITO target in a mixture of argon and nitrogen gas at room temperature. The blue transmittance at 455 nm rises from 63% to 83% after nitrogen doping. The resistivity of the ITO film reduces from 4.6 × 10-3 (undoped film) to 5.7 × 10-4 Ω cm (N-doped film). The X-ray photoelectron spectroscopy data imply that the binding energy of the In3d5/2 peak is declined 0.05 eV after nitrogen doping. The high resolution transmission electron microscope images show that the nitrogen loss density of the GaN/ITO interface with N-doped ITO film is smaller than that of the GaN/ITO interface with undoped ITO film. The forward turn-on voltage of gallium nitride light emitting diode reduces by 0.5 V after nitrogen doping. The fabrication of the N-doped ITO film is conducive to modify the N component of the interface between GaN and ITO layer.

  11. Low-Damage Indium Tin Oxide Formation on Organic Layers Using Unique Cylindrical Sputtering Module and Application in Transparent Organic Light-Emitting Diodes

    NASA Astrophysics Data System (ADS)

    Yamamoto, Hidetoshi; Oyamada, Takahito; Hale, William; Aoshima, Shoichi; Sasabe, Hiroyuki; Adachi, Chihaya

    2006-02-01

    We demonstrate a low-damage technique for forming an indium tin oxide (ITO) layer on an organic layer by using a unique cylindrical sputtering module and the fabrication of high-performance transparent organic light-emitting diodes (TOLEDs). The ITO target has an off-axis alignment to the substrate, and it confines plasma to the inside of the module, thereby forming ITO with little damage to the underlying organic layers. We found that the composition ratio of In2O3 (90%) and SnO2 (10%) in the deposited film is the same as the target composition ratio, and that the composition ratio distribution was spatially uniform, showing no angular dependence. We fabricated an ITO [110 nm]/4,4'-bis[N(1-naphthyl)-N-phenyl-amino]biphenyl (α-NPD) [50 nm]/tris-(8-hydroxy-quinoline)aluminum (Alq3) [30 nm]/Cs:phenyldipyrenylphosphine oxide (POPy2) [20 nm]/ITO [100 nm] device, using a cylindrical target for the top ITO cathode fabrication. The device showed excellent J-V characteristics, with a current density of J=883 mA/cm2 at an applied voltage of 10 V and a maximum external quantum efficiency of ηext=0.76%.

  12. p-Cu2O/SiO x /n-SiC/n-Si memory diode fabricated with room-temperature-sputtered n-SiC and SiO x

    NASA Astrophysics Data System (ADS)

    Yamashita, Atsushi; Tsukamoto, Takahiro; Suda, Yoshiyuki

    2016-12-01

    We investigated low-temperature fabrication processes for our previously proposed pn memory diode with a p-Cu2O/SiC x O y /n-SiC/n-Si structure having resistive nonvolatile memory and rectifying behaviors suitable for a cross-point memory array with the highest theoretical density. In previous fabrication processes, n-SiC was formed by sputtering at 1113 K, and SiC x O y and p-Cu2O were formed by the thermal oxidation of n-SiC and Cu at 1073 and 473 K, respectively. In this study, we propose a pn memory diode with a p-Cu2O/SiO x /n-SiC/n-Si structure, where n-SiC and SiO x layers are deposited by sputtering at room temperature. The proposed processes enable the fabrication of the pn memory diode at temperatures of not more than 473 K, which is used for the formation of p-Cu2O. This memory diode exhibits good nonvolatile memory and rectifying characteristics. These proposed low-temperature fabrication processes are expected to expand the range of fabrication processes applicable to current LSI fabrication processes.

  13. Numerical simulation of cross field amplifiers

    SciTech Connect

    Eppley, K.

    1990-01-01

    Cross field amplifiers (CFA) have been used in many applications where high power, high frequency microwaves are needed. Although these tubes have been manufactured for decades, theoretical analysis of their properties is not as highly developed as for other microwave devices such as klystrons. One feature distinguishing cross field amplifiers is that the operating current is produced by secondary emission from a cold cathode. This removes the need for a heater and enables the device to act as a switch tube, drawing no power until the rf drive is applied. However, this method of generating the current does complicate the simulation. We are developing a simulation model of cross field amplifiers using the PIC code CONDOR. We simulate an interaction region, one traveling wavelength long, with periodic boundary conditions. An electric field with the appropriate phase velocity is imposed on the upper boundary of the problem. Evaluation of the integral of E{center dot}J gives the power interchanged between the wave and the beam. Given the impedance of the structure, we then calculate the change in the traveling wave field. Thus we simulate the growth of the wave through the device. The main advance of our model over previous CFA simulations is the realistic tracking of absorption and secondary emission. The code uses experimental curves to calculate secondary production as a function of absorbed energy, with a theoretical expression for the angular dependence. We have used this code to model the 100 MW X-band CFA under construction at SLAC, as designed by Joseph Feinstein and Terry Lee. We are examining several questions of practical interest, such as the power and spectrum of absorbed electrons, the minimum traveling wave field needed to initiate spoke formation, and the variation of output power with dc voltage, anode-cathode gap, and magnetic field. 5 refs., 8 figs.

  14. Sputter target

    DOEpatents

    Gates, Willard G.; Hale, Gerald J.

    1980-01-01

    The disclosure relates to an improved sputter target for use in the deposition of hard coatings. An exemplary target is given wherein titanium diboride is brazed to a tantalum backing plate using a gold-palladium-nickel braze alloy.

  15. A kinetic cross-field streaming instability

    NASA Technical Reports Server (NTRS)

    Wu, C. S.; Winske, D.; Papadopoulos, K.; Zhou, Y. M.; Tsai, S. T.; Guo, S. C.

    1983-01-01

    In a high-beta plasma the so-called modified-two-stream instability, which results from strongly magnetized electrons drifting relative to unmagnetized ions across a homogeneous magnetic field, is misnamed because the mode is highly kinetic, particularly when the relative streaming velocity exceeds the Alfven speed of the plasma. This kinetic cross-field streaming instability is investigated in detail, examining the effect of the electromagnetic terms and the stability boundaries in both low- and high-beta plasmas. An approximate dispersion relation showing the relation of this mode to the whistler is derived and solutions of it are compared with those obtained from the exact dispersion relation. The kinetic mode, unlike the usual modified-two-stream instability, is not stabilized by electromagnetic effects when the relative electron-ion drift speed exceeds the Alfven speed.

  16. Demagnetisation by crossed fields in superconductors

    NASA Astrophysics Data System (ADS)

    Campbell, Archie; Baghdadi, Mehdi; Patel, Anup; Zhou, Difan; Huang, K. Y.; Shi, Yunhua; Coombs, Tim

    2017-03-01

    A study has been made of the decay of the trapped magnetisation in superconductors when exposed to a crossed field. Numerical results have been compared with the theory of Brandt and Mikitik (2002 Phys. Rev. Lett. 89 027002) which solves the problem for a thin strip superconductor. FlexPDE with the A formulation and COMSOL with the H formulation were both used. Simulations of a strip with a cross section aspect ratio of 20 showed good agreement with theory both for the case of a transverse field larger than the transverse penetration field and for one smaller. In the latter case the magnetisation saturates as predicted, however the simulations show a slow decay after many cycles. In the case of stacked YBCO tapes the movement of flux lines is very small and the effects of the reversible motion were investigated. This can decrease the decay initially for very thin decoupled tapes, but cause a steady decay after very large numbers of cycles. Simulations on stacked strips showed that the decay constant increased approximately linearly with the number of strips. When combined with the theory for one tape this can explain the very slow decay observed in previous experiments. Experimental results were qualitatively in agreement with theory and simulations but showed some discrepancies. However there are a number of differences between the experimental situation and theory so good agreement is not expected.

  17. Sputtering and ion plating

    NASA Technical Reports Server (NTRS)

    1972-01-01

    The proceedings of a conference on sputtering and ion plating are presented. Subjects discussed are: (1) concepts and applications of ion plating, (2) sputtering for deposition of solid film lubricants, (3) commercial ion plating equipment, (4) industrial potential for ion plating and sputtering, and (5) fundamentals of RF and DC sputtering.

  18. 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.

  19. 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.

  20. Multitarget sequential sputtering apparatus

    NASA Technical Reports Server (NTRS)

    Shima, R. (Inventor)

    1975-01-01

    The development and characteristics of a sputtering apparatus are discussed. A potential difference is applied between the cathode and anode to produce a plasma for each target which is sputtered by accelerated ions within the plasma. The process of sputtering for various materials is described. Diagrams of the unit are provided.

  1. Cathode driven high gain crossed-field amplifier

    NASA Astrophysics Data System (ADS)

    1983-07-01

    The objective of this three-phase program is to achieve the design of a cathode driven high gain re-entrant Crossed Field Amplifier capable of meeting the parameters of Raytheon Company specification No. 968838 dated 10 May 1978. The effort includes the fabrication and test of three developmental and four final configuration tubes. One final configuration tube will be life tested and two will be delivered to the Navy. The tasks discussed during this report period relate to the cold tests performed on various subassemblies of model no. 4 and on the sealed-in model no. 4 of the S-band high gain cathode driven crossed field amplifier. Based on the performance of model no. 3 certain remedial measures have been implemented in model no. 4 that have resulted in the elimination of key resonances within the tube and an improvement in the isolation between the cathode and anode circuits.

  2. Kr II and Xe II axial velocity distribution functions in a cross-field ion source

    NASA Astrophysics Data System (ADS)

    Lejeune, A.; Bourgeois, G.; Mazouffre, S.

    2012-07-01

    Laser induced fluorescence measurements were carried out in a cross-field ion source to examine the behaviour of the axial ion velocity distribution functions (VDFs) in the expanding plasma. In the present paper, we focus on the axial VDFs of Kr II and Xe II ions. We examine the contourplots in a 1D-phase space (x,vx) representation in front of the exhaust channel and along the centerline of the ion source. The main ion beam, whose momentum corresponds to the ions that are accelerated through the whole potential drop, is observed. A secondary structure reveals the ions coming from the opposite side of the channel. We show that the formation of the neutralized ion flow is governed by the annular geometry. The assumption of a collisionless shock or a double layer due to supersonic beam interaction is not necessary. A non-negligible fraction of slow ions originates in local ionization or charge-exchange collision events between ions of the expanding plasma and atoms of the background residual gas. Slow ions that are produced near the centerline in the vicinity of the exit plane are accelerated toward the source body with a negative velocity leading to a high sputtering of front face. On the contrary, the ions that are produced in the vicinity of the channel exit plane are partially accelerated by the extended electric field.

  3. Crossed-field divertor for a plasma device

    DOEpatents

    Kerst, Donald W.; Strait, Edward J.

    1981-01-01

    A divertor for removal of unwanted materials from the interior of a magnetic plasma confinement device includes the division of the wall of the device into segments insulated from each other in order to apply an electric field having a component perpendicular to the confining magnetic field. The resulting crossed-field drift causes electrically charged particles to be removed from the outer part of the confinement chamber to a pumping chamber. This method moves the particles quickly past the saddle point in the poloidal magnetic field where they would otherwise tend to stall, and provides external control over the rate of removal by controlling the magnitude of the electric field.

  4. Noise Studies on Injected-Beam Crossed-Field Devices.

    DTIC Science & Technology

    1980-11-01

    In the gyrotron, where l magnetron injection guns are used, noise under crossed-field conditions is a limiting factor in the performance of the gun...charge I affected the behavior of the beam. Two factors which seemed to give rise to these effects appeared to be in the noise generated near the cathode...circuit I bars, or 0.270". The essential electrical properties of the meander circuit, the delay ratio (C/ vph ) and coupling impedance at the level of the

  5. The Cross-field Current Instability for Substorm Expansion Onset

    SciTech Connect

    Lui, A. T. Y.

    2011-01-04

    A challenging problem in the topic of the nonlinear dynamics of the magnetosphere is the physical process responsible for the onset of magnetospheric substorms. The early collaboration with Dr. K. Papadopoulos has led to the proposal of a kinetic plasma instability, called the cross-field current instability, as the onset process. This has developed into a full-blown research effort, supplementing the initial theoretical analysis with in-depth data analysis and particle simulations. Several theoretical predictions based on this instability are successfully verified in observations. Data from the present NASA THEMIS mission provide some evidence for its validity. Further investigations for this substorm onset process are also discussed.

  6. Ion beam sputter etching

    NASA Technical Reports Server (NTRS)

    Banks, Bruce A.; Rutledge, Sharon K.

    1986-01-01

    An ion beam etching process which forms extremely high aspect ratio surface microstructures using thin sputter masks is utilized in the fabrication of integrated circuits. A carbon rich sputter mask together with unmasked portions of a substrate is bombarded with inert gas ions while simultaneous carbon deposition occurs. The arrival of the carbon deposit is adjusted to enable the sputter mask to have a near zero or even slightly positive increase in thickness with time while the unmasked portions have a high net sputter etch rate.

  7. Nonlinear analysis of generalized cross-field current instability

    NASA Technical Reports Server (NTRS)

    Yoon, Peter H.; Lui, Anthony T. Y.

    1993-01-01

    Analysis of the generalized cross-field current instability is carried out in which cross-field drift of both the ions and electrons and their temperatures are permitted to vary in time. The unstable mode under consideration is the electromagnetic generalization of the classical modified-two-stream instability. The generalized instability is made of the modified-two-stream and ion-Weibel modes. The relative importance of the features associated with the ion-Weibel mode and those of the modified-two-stream mode is assessed. Specific applications are made to the Earth's neutral sheet prior to substorm onset and to the Earth's bow shock. The numerical solution indicates that the ion-Weibel mode dominates in the Earth's neutral sheet environment. In contrast, the situation for the bow shock is dominated by the modified-two-stream mode. Notable differences are found between the present calculation and previous results on ion-Weibel mode which restrict the analysis to only parallel propagating waves. However, in the case of Earth's bow shock for which the ion-Weibel mode plays no important role, the inclusion of the electromagnetic ion response is found to differ little from the previous results which treats ions responding only to the electrostatic component of the excited waves.

  8. Nonlinear growth of electron holes in cross-field wakes

    NASA Astrophysics Data System (ADS)

    Hutchinson, Ian; Haakonsen, C. B.; Zhou, C.

    2015-11-01

    Cross-field plasma flow past an obstacle is key to the physics underlying Mach-probes, space-craft charging, and the wakes of non-magnetic bodies: the solar-wind wake of the moon is a typical example. We report associated new nonlinear instability mechanisms. Ions are accelerated along the B-field into the wake, forming two beams, but they are not initially unstable to ion two-stream instabilities. Electron Langmuir waves become unstable much earlier because of an electron velocity-distribution distortion called the ``dimple''. The magnetic field, perpendicular to the flow, defines the 1-D direction of particle dynamics. In high-fidelity PIC simulations at realistic mass ratio, small electron holes--non-linearly self-binding electron density deficits--are spawned by the dimple in fe (v) near the phase-space separatrix. Most holes accelerate rapidly out of the wake, along B. However, some remain at very low speed, and grow until they are large enough to disrupt the two ion-streams, well before the ions are themselves linearly unstable. This non-linear hole growth is caused by the same mechanism that causes the dimple: cross-field drift from a lower to a higher density. Related mechanisms cause plasma near magnetized Langmuir probes to be unsteady. Partially supported by the NSF/DOE Basic Plasma Science Partnership grant DE-SC0010491.

  9. Nonlinear self-consistent theory for crossed-field devices

    NASA Astrophysics Data System (ADS)

    Riyopoulos, S.

    1993-04-01

    A closed, nonlinear set of fluid equations that is based on the electron guiding-center orbits and is generally applicable to the analysis of crossed-field, slow-wave devices, is developed. The equations are used to model the behavior of the crossed-field amplifier. The dielectric response from the spoke charge is self-consistently included. A mean-field approximation is introduced to express the effect of the spoke charge on the rf mode profile. The dielectric modifications are then parametrized by an average amplitude factor Λ^ and an average phase shift ψ^ from the vacuum values. In the synchronous with the rf signal frame of reference the streamlines follow the equipotential surfaces of the transformed fields. In the steady state, the flow is incompressible. A uniform-density, constant-height electron hub feeds the current spokes. The secondary electron production at the cathode is computed self-consistently through the secondary-emission coefficient and the average impact energy. The spoke current is determined by the difference of the E×B drift at the top of the hub from the rf phase velocity. At small space-charge density relative to the Brillouin density, the dielectric corrections enter as a rotation eiψ^ of the complex growth rate relative to the growth without spoke self-fields. The numerical solutions for arbitrary space charge are compared with previous results without spoke-field effects. An increase in the rf gain and in the anode dc current is observed at any given operation point, despite a small drop in the efficiency. It is concluded that the increase in the rf field strength in the anode-cathode space, caused by the spoke self-field, compensates for the detuning effects from the modifications on the rf mode profile. In reentrant devices, the recycling of the space charge further increases the output power and the level of noise generated by the output-input feedback.

  10. Sputtering of uranium

    NASA Technical Reports Server (NTRS)

    Gregg, R.; Tombrello, T. A.

    1978-01-01

    Results are presented for an experimental study of the sputtering of U-235 atoms from foil targets by hydrogen, helium, and argon ions, which was performed by observing tracks produced in mica by fission fragments following thermal-neutron-induced fission. The technique used allowed measurements of uranium sputtering yields of less than 0.0001 atom/ion as well as yields involving the removal of less than 0.01 monolayer of the uranium target surface. The results reported include measurements of the sputtering yields for 40-120-keV protons, 40-120-keV He-4(+) ions, and 40- and 80-keV Ar-40(+) ions, the mass distribution of chunks emitted during sputtering by the protons and 80-keV Ar-40(+) ions, the total chunk yield during He-4(+) sputtering, and some limited data on molecular sputtering by H2(+) and H3(+). The angular distribution of the sputtered uranium is discussed, and the yields obtained are compared with the predictions of collision cascade theory.

  11. Magnetically attached sputter targets

    DOEpatents

    Makowiecki, D.M.; McKernan, M.A.

    1994-02-15

    An improved method and assembly for attaching sputtering targets to cathode assemblies of sputtering systems which includes a magnetically permeable material is described. The magnetically permeable material is imbedded in a target base that is brazed, welded, or soldered to the sputter target, or is mechanically retained in the target material. Target attachment to the cathode is achieved by virtue of the permanent magnets and/or the pole pieces in the cathode assembly that create magnetic flux lines adjacent to the backing plate, which strongly attract the magnetically permeable material in the target assembly. 11 figures.

  12. Magnetically attached sputter targets

    DOEpatents

    Makowiecki, Daniel M.; McKernan, Mark A.

    1994-01-01

    An improved method and assembly for attaching sputtering targets to cathode assemblies of sputtering systems which includes a magnetically permeable material. The magnetically permeable material is imbedded in a target base that is brazed, welded, or soldered to the sputter target, or is mechanically retained in the target material. Target attachment to the cathode is achieved by virtue of the permanent magnets and/or the pole pieces in the cathode assembly that create magnetic flux lines adjacent to the backing plate, which strongly attract the magnetically permeable material in the target assembly.

  13. Fundamental sputtering studies: Nonresonant ionization of sputtered neutrals

    SciTech Connect

    Burnett, J.W.; Pellin, M.J.; Calaway, W.F.; Gruen, D.M. ); Yates, J.T. Jr. . Dept. of Chemistry)

    1989-01-04

    Because of the practical importance of sputtering, numerous theories and computer simulations are used for predicting many aspects of the sputtering process. Unfortunately, many of the calculated sputtering results are untested by experiment. Until recently, most sputtering experiments required either very high ion fluences or the detection of only minor constituents of the sputtered flux, i.e., ions. These techniques may miss the subtleties involved in the sputtering process. High-detection-efficiency mass spectrometry, coupled with the laser ionization of neutral atoms, allows the detection of the major sputtered species with very low incident ion fluences. The depth-of-origin of sputtered atoms is one example of an important but poorly understood aspect of the sputtering process. By following the sputtering yield of a substrate atom with various coverages of an adsorbed overlayer, the depth of origin of sputtered atoms has been determined. Our results indicate that two-thirds of the sputtered flux originates in the topmost atomic layer. The ion-dose dependence of sputtering yields has long been assumed to be quite minor for low- to-moderate primary ion fluences. We have observed a two-fold decrease in the sputtering yield of the Ru(0001) surface for very low primary ion fluences. Data analysis results in a cross section for damage of 2.7 {plus minus} 1.0 {times} 10{sup {minus}15}cm{sup 2}. 40 refs., 3 figs., 2 tabs.

  14. Solar coronal loop heating by cross-field wave transport

    NASA Technical Reports Server (NTRS)

    Amendt, Peter; Benford, Gregory

    1989-01-01

    Solar coronal arches heated by turbulent ion-cyclotron waves may suffer significant cross-field transport by these waves. Nonlinear processes fix the wave-propagation speed at about a tenth of the ion thermal velocity, which seems sufficient to spread heat from a central core into a large cool surrounding cocoon. Waves heat cocoon ions both through classical ion-electron collisions and by turbulent stochastic ion motions. Plausible cocoon sizes set by wave damping are in roughly kilometers, although the wave-emitting core may be only 100 m wide. Detailed study of nonlinear stabilization and energy-deposition rates predicts that nearby regions can heat to values intermediate between the roughly electron volt foot-point temperatures and the about 100 eV core, which is heated by anomalous Ohmic losses. A volume of 100 times the core volume may be affected. This qualitative result may solve a persistent problem with current-driven coronal heating; that it affects only small volumes and provides no way to produce the extended warm structures perceptible to existing instruments.

  15. Stationary to nonstationary transition in crossed-field devices

    SciTech Connect

    Marini, Samuel; Rizzato, Felipe B.; Pakter, Renato

    2016-03-15

    The previous results based on numerical simulations showed that a cold electron beam injected in a crossed field gap does not reach a time independent stationary state in the space charge limited regime [P. J. Christenson and Y. Y. Lau, Phys. Plasmas 1, 3725 (1994)]. In this work, the effect of finite injection temperature in the transition from stationary to nonstationary states is investigated. A fully kinetic model for the electron flow is derived and used to determine the possible stationary states of the system. It is found that although there is always a stationary solution for any set of parameters, depending on the injection temperature the electron flow becomes very sensitive to fluctuations and the stationary state is never reached. By investigating the nonlinear dynamics of a characteristic electron, a theory based on a single free parameter is constructed to predict when the transition between stationary and nonstationary states occurs. In agreement with the previous numerical results, the theory indicates that for vanishing temperatures the system never reaches the time independent stationary state in the space charge limited regime. Nevertheless, as the injection temperature is raised it is found a broad range of system parameters for which the stationary state is indeed attained. By properly adjusting the free parameter in the theory, one can be able to describe, to a very good accuracy, when the transition occurs.

  16. PIC Simulation for ICF Plasma Sputter Coater

    NASA Astrophysics Data System (ADS)

    Wu, W.; Huang, H.; Parks, P. B.; Chan, V. S.; Walton, C. C.; Wilks, S. C.

    2010-11-01

    To satisfy mesh spacing constraint δ/λDebye<=1 particle In Cell (PIC) simulations at 25x reduced cathode currents levels are used to numerically model the distribution of currents, electrostatic potentials and particle kinetics in a Type II ``unbalanced'' cylindrically symmetric magnetron discharge used for Be sputter coating of ICF capsules. Simulation indicates a strong magnetic field confinement of the plasma in the closed field lines region adjacent to cathode, and accompanying cross-field line plasma diffusion into the open-field line region connected to wall/anode. A narrow Charles-Langmuir sheath and a pre-sheath that is ˜10x wider due to the existence of the B-field are observed. The effects of varying boundary conditions, e.g., the separation between the anode/cathode, the anode bias voltage, etc., are studied, which is expected to aid experimentalists in turning these ``knobs'' for better coating qualities. We also show that the etch rate due to sputtering of Be targets predicted by the results of our PIC simulations, after rescaling to experimental conditions, agrees with experiments.

  17. Influence of sputtering power on the optical properties of ITO thin films

    SciTech Connect

    K, Aijo John; M, Deepak T, Manju; Kumar, Vineetha V.

    2014-10-15

    Tin doped indium oxide films are widely used in transparent conducting coatings such as flat panel displays, crystal displays and in optical devices such as solar cells and organic light emitting diodes due to the high electrical resistivity and optical transparency in the visible region of solar spectrum. The deposition parameters have a commendable influence on the optical and electrical properties of the thin films. In this study, ITO thin films were prepared by RF magnetron sputtering. The properties of the films prepared under varying sputtering power were compared using UV- visible spectrophotometry. Effect of sputtering power on the energy band gap, absorption coefficient and refractive index are investigated.

  18. 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.

  19. 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.

  20. Physics of ion sputtering

    SciTech Connect

    Robinson, M.T.

    1984-04-01

    The ejection of atoms by the ion bombardment of solids is discussed in terms of linear collision cascade theory. A simple argument describes the energies of the ejecta, but elaborate models are required to obtain accurate sputtering yields and related quantities. These include transport theoretical models based on linearized Boltzmann equations, computer simulation models based on the binary collision approximation, and classical many-body dynamical models. The role of each kind of model is discussed. Several aspects of sputtering are illustrated by results from the simulation code MARLOWE. 20 references, 6 figures.

  1. Incongruent sputtering in metal oxides

    NASA Astrophysics Data System (ADS)

    Langell, M. A.

    1987-11-01

    Preferential sputtering has been observed for NiO(100) and CoO(100) under low fluxes of 2 keV Ar +, with oxygen/metal sputtering yields a strong function of substrate temperature. Auger electron spectroscopy (AES) and X-ray photoelectron spectroscopy (XPS) were used to follow the chemical and compositional nature of the surface for substrates prepared and characterized under UHV. Using O/M AES ratios as a measure of oxygen content, congruent sputtering was found for the oxides at 300 K for fluences of up to 10 17 Ar +/cm 2 and threshold temperatures for sputter reduction were observed at 350 K and 500 K for NiO and CoO, respectively. The relatively close thresholds for NiO and CoO sputter reduction argue against current thermal sputtering theory which predicts incongruent sputtering through oxygen vaporization. The temperature dependence of the O/M sputtering yields indicates that metal oxide sputtering is far more complex than current theory is able to describe. XPS data show evidence that adsorbed oxygen species, distinct from lattice oxygen, have formed on surfaces which have undergone sputter reduction and these species are postulated to play a role in the sputtering mechanism. MnO(100) crystals show no evidence for preferential sputtering for substrate temperature of up to 1000 K.

  2. Data Diode

    SciTech Connect

    2014-11-07

    The Data Diode is a data security technology that can be deployed within an organization's defense-in-depth computer network strategy for information assurance. For internal security, the software creates an environment within the network where an organization's approved users can work freely inside an enclave of protected data, but file transfers out of the enclave is restricted. For external security, once a network intruder has penetrated the network, the intruder is able to "see" the protected data, but is unable to download the actual data. During the time it takes for the intruder to search for a way around the obstacle created by the Data Diode, the network's intrusion detection technologies can locate and thwart the malicious intent of the intruder. Development of the Data Diode technology was made possible by funding from the Intelligence Advanced Research Projects Activity (IARPA).

  3. Nonlinear transmission sputtering

    NASA Astrophysics Data System (ADS)

    Bitensky, I. S.; Sigmund, P.

    1996-05-01

    General expressions have been derived for the nonlinear yield of transmission sputtering for an incident polyatomic ion under the assumption that the molecule breaks up on entering the target and that sputter yields are enhanced due to proximity of atomic trajectories. Special attention is given to the case of negligible Coulomb explosion where projectile atoms penetrate independently. For weakly overlapping trajectories, the yield enhancement factor of a polyatomic molecule can be expressed by that of a diatom, amended with a correction for triple correlations if necessary. This expression is in good agreement with recent experimental findings on phenylalanine targets. Pertinent results on multiple scattering of atomic ions are reviewed and applied to independently-moving fragment atoms. The merits of measurements at variable layer thickness in addition to variable projectile energy are mentioned.

  4. Sputtered Thin Film Research

    DTIC Science & Technology

    1976-02-01

    sense of the radiation induced thresh- old voltage’shi- c observed was not alway. consistent, although the same process eonaluoa* were used to...deposition of the hafnium dioxide. It was found that this process modification did not have a significant effect on the radiation hardness. k.l...DISCUSSION OF RESULTS AND CONCLUSIONS \\ Reactively sputtered hafnium dioxide has been demonstrated’ co be a radiation tolerant gate dielectric which

  5. Noble gas sputtering calculations using TRIM

    SciTech Connect

    Greene, J.P.; Nemanich, J.; Thomas, G.E.; Schiel, S.L.

    1996-12-31

    In conjunction with our experimental work on saddle field ion sputtering, we have attempted to apply the Monte Carlo program TRIM (Transport of Ions in Matter) to calculate the sputter yields for a variety of noble gas sputtering applications. Comparison with experiments are shown. Information extracted from these analyses have proved useful in optimizing the experimental sputtering parameters. Calculated sputter yields obtained utilizing TRIM are presented for noble gas sputtering of a variety of materials common to nuclear target production.

  6. Theory of instabilities in crossed-field discharges at low pressures

    SciTech Connect

    Abolmasov, Sergey N.; Samukawa, Seiji; Bizyukov, Alexander A.

    2007-09-15

    Anode layer thruster, Penning, cylindrical magnetron, and inverted-magnetron discharges all behave, at pressures below about 10{sup -4} Torr, as crossed-field discharges. At such low pressures, a crossed-field discharge is pure electron plasma and most of the discharge voltage appears across an electron sheath so that the electric field is orthogonal to the magnetic field. The principal difficulties in the practical use of these discharges in this pressure range arise from instabilities in the discharge, which are commonly attributed to diocotron instabilities in the electron sheath. On the contrary, this paper describes a theory of the electron sheath based on the classical expression for the cross-field mobility of electrons. The theory predicts that the observed instabilities, accompanied by appearance of pulses of excess energy electrons at the cathode(s) and nonlinearity in the discharge characteristics, are simply the result of periodic travel of the electron sheath through the discharge gap.

  7. Low-Energy Sputtering Research

    NASA Technical Reports Server (NTRS)

    Ray, P. K.; Shutthanandan, V.

    1999-01-01

    An experimental study is described to measure low-energy (less than 600 eV) sputtering yields of molybdenum with xenon ions using Rutherford backscattering spectroscopy (RBS) and secondary neutral mass spectroscopy (SNMS). An ion gun was used to generate the ion beam. The ion current density at the target surface was approximately 30 (micro)A/sq cm. For RBS measurements, the sputtered material was collected on a thin aluminum strip which was mounted on a semi-circular collector plate. The target was bombarded with 200 and 500 eV xenon ions at normal incidence. The differential sputtering yields were measured using the RBS method with 1 MeV helium ions. The differential yields were fitted with a cosine fitting function and integrated with respect to the solid angle to provide the total sputtering yields. The sputtering yields obtained using the RBS method are in reasonable agreement with those measured by other researchers using different techniques. For the SNMS measurements, 150 to 600 eV xenon ions were used at 50deg angle of incidence. The SNMS spectra were converted to sputtering yields for perpendicular incidence by normalizing SNMS spectral data at 500 eV with the yield measured by Rutherford backscattering spectrometry. Sputtering yields as well as the shape of the yield-energy curve obtained in this manner are in reasonable agreement with those measured by other researchers using different techniques. Sputtering yields calculated by using two semi-spherical formulations agree reasonably well with measured data. The isotopic composition of secondary ions were measured by bombarding copper with xenon ions at energies ranging from 100 eV to 1.5 keV. The secondary ion flux was found to be enriched in heavy isotopes at low incident ion energies. The heavy isotope enrichment was observed to decrease with increasing impact energy. Beyond 700 eV, light isotopes were sputtered preferentially with the enrichment remaining nearly constant.

  8. Sputtering. [as deposition technique in mechanical engineering

    NASA Technical Reports Server (NTRS)

    Spalvins, T.

    1976-01-01

    This paper primarily reviews the potential of using the sputtering process as a deposition technique; however, the manufacturing and sputter etching aspects are also discussed. Since sputtering is not regulated by classical thermodynamics, new multicomponent materials can be developed in any possible chemical composition. The basic mechanism for dc and rf sputtering is described. Sputter-deposition is described in terms of the unique advantageous features it offers such as versatility, momentum transfer, stoichiometry, sputter-etching, target geometry (coating complex surfaces), precise controls, flexibility, ecology, and sputtering rates. Sputtered film characteristics, such as strong adherence and coherence and film morphology, are briefly evaluated in terms of varying the sputtering parameters. Also described are some of the specific industrial areas which are turning to sputter-deposition techniques.

  9. Sputtering. [as deposition technique in mechanical engineering

    NASA Technical Reports Server (NTRS)

    Spalvins, T.

    1976-01-01

    This paper primarily reviews the potential of using the sputtering process as a deposition technique; however, the manufacturing and sputter etching aspects are also discussed. Since sputtering is not regulated by classical thermodynamics, new multicomponent materials can be developed in any possible chemical composition. The basic mechanism for dc and rf sputtering is described. Sputter-deposition is described in terms of the unique advantageous features it offers such as versatility, momentum transfer, stoichiometry, sputter-etching, target geometry (coating complex surfaces), precise controls, flexibility, ecology, and sputtering rates. Sputtered film characteristics, such as strong adherence and coherence and film morphology, are briefly evaluated in terms of varying the sputtering parameters. Also described are some of the specific industrial areas which are turning to sputter-deposition techniques.

  10. The adapting of the crossed-field directional amplifier to the requirements of the SPS

    NASA Technical Reports Server (NTRS)

    Brown, W. C.

    1980-01-01

    Progress in adapting the crossed-field directional amplifier to the SPS is reviewed. Special emphasis is given to (1) recent developments in controlling the phase and amplitude of the microwave power output, (2) a received architecture for its placement in the subarray, and (3) recent developments in the critical pivotal areas of noise, potential cathode life, and efficiency.

  11. Sputtering in mercury ion thrusters

    NASA Technical Reports Server (NTRS)

    Mantenieks, M. A.; Rawlin, V. K.

    1979-01-01

    A model, which assumes that chemisorption is the dominant mechanism, is applied to the sputtering rate measurements of the screen grid of a 30 cm thruster in the presence of nitrogen. The model utilizes inputs from a variety of experimental and analytical sources. The model of environmental effects on sputtering was applied to thruster conditions of low discharge voltage and a discussion of the comparison of theory and experiment is presented.

  12. Improved refractory coatings. [sputtered coatings on substrates that form stable nitrides

    NASA Technical Reports Server (NTRS)

    Brainard, W. A. (Inventor)

    1980-01-01

    The adhesion, friction and wear properties of sputtered refractory coatings on substrates of materials that form stable nitrides are enhanced by placing each substrate directly below a titanium carbide target of a commercial radiofrequency diode apparatus in a vacuum chamber. Nitrogen is bled into the system through a nozzle resulting in a small partial pressure of about 0.5% to 2.5% during the first two minutes of deposition. The flow of nitrogen is then stopped, and the sputtering ambient is reduced to pure argon through a nozzle without interrupting the sputtering process. When nitrogen is deliberately introduced during the crucial interface formation, some of the titanium at the interface reacts to form titanium nitride while the metal of the substrate also forms the nitride. These two nitrides atomically mixed together in the interfacial region act to more strongly bond the growing titanium carbide coating as it forms on the substrate.

  13. Two-dimensional space-charge-limited flows in a crossed-field gap

    SciTech Connect

    Koh, W. S.; Ang, L. K.

    2007-04-02

    This letter presents a two-dimensional (2D) model of space-charge-limited current in a planar crossed-field gap with a magnetic strength of B/B{sub H}=0-3, where B{sub H} is the Hull cutoff magnetic field. The electrons are emitted from an infinite length strip of finite width W comparable to the gap spacing D. It is found that the 2D enhancement of the crossed-field limiting current is 1+Fx4D/({pi}W), where F (=0.05-0.5) is a normalized mean-position factor, and it is a function of B/B{sub H}. Good agreement has been obtained in comparisons with particle-in-cell simulation.

  14. Effect of electron thermal anisotropy on the kinetic cross-field streaming instability

    NASA Technical Reports Server (NTRS)

    Tsai, S. T.; Tanaka, M.; Gaffey, J. D., Jr.; Wu, C. S.; Da Jornada, E. H.; Ziebell, L. F.

    1984-01-01

    The investigation of the kinetic cross-field streaming instability, motivated by the research of collisionless shock waves and previously studied by Wu et al. (1983), is discussed more fully. Since in the ramp region of a quasi-perpendicular shock electrons can be preferentially heated in the direction transverse to the ambient magnetic field, it is both desirable and necessary to include the effect of the thermal anisotropy on the instability associated with a shock. It is found that Te-perpendicular greater than Te-parallel can significantly enhance the peak growth rate of the cross-field streaming instability when the electron beta is sufficiently high. Furthermore, the present analysis also improves the analytical and numerical solutions previously obtained.

  15. Electron Cross-field Transport in a Low Power Cylindrical Hall Thruster

    SciTech Connect

    A. Smirnov; Y. Raitses; N.J. Fisch

    2004-06-24

    Conventional annular Hall thrusters become inefficient when scaled to low power. Cylindrical Hall thrusters, which have lower surface-to-volume ratio, are therefore more promising for scaling down. They presently exhibit performance comparable with conventional annular Hall thrusters. Electron cross-field transport in a 2.6 cm miniaturized cylindrical Hall thruster (100 W power level) has been studied through the analysis of experimental data and Monte Carlo simulations of electron dynamics in the thruster channel. The numerical model takes into account elastic and inelastic electron collisions with atoms, electron-wall collisions, including secondary electron emission, and Bohm diffusion. We show that in order to explain the observed discharge current, the electron anomalous collision frequency {nu}{sub B} has to be on the order of the Bohm value, {nu}{sub B} {approx} {omega}{sub c}/16. The contribution of electron-wall collisions to cross-field transport is found to be insignificant.

  16. Effect of electron thermal anisotropy on the kinetic cross-field streaming instability

    NASA Technical Reports Server (NTRS)

    Tsai, S. T.; Tanaka, M.; Gaffey, J. D., Jr.; Wu, C. S.; Da Jornada, E. H.; Ziebell, L. F.

    1984-01-01

    The investigation of the kinetic cross-field streaming instability, motivated by the research of collisionless shock waves and previously studied by Wu et al. (1983), is discussed more fully. Since in the ramp region of a quasi-perpendicular shock electrons can be preferentially heated in the direction transverse to the ambient magnetic field, it is both desirable and necessary to include the effect of the thermal anisotropy on the instability associated with a shock. It is found that Te-perpendicular greater than Te-parallel can significantly enhance the peak growth rate of the cross-field streaming instability when the electron beta is sufficiently high. Furthermore, the present analysis also improves the analytical and numerical solutions previously obtained.

  17. Electronic sputtering of carbon allotropes

    NASA Astrophysics Data System (ADS)

    Ghosh, S.; Avasthi, D. K.; Tripathi, A.; Kabiraj, D.; Singh, S.; Misra, D. S.

    2004-06-01

    Electronic sputtering of different allotropes of carbon (diamond, graphite, fullerene, a-C and a-C:H) are studied under 200 MeV Au 15+ ion irradiation. On-line elastic recoil detection analysis (ERDA) and catcher technique is employed to measure the sputtering yield of carbon from these allotropes. Erosion behavior is distinctly different in different allotropes as observed by ERDA. Hardest known material diamond does not show any sputtering within the detection limit of the experimental set up, whereas the soft polymerlike a-C:H shows highest sputtering yield (5.8 × 10 5 atoms/ion). Yields in case of other allotropes are 1 × 10 3 atoms/ion (graphite), 3 × 10 4 atoms/ion (fullerene), 1.8 × 10 4 atoms/ion (a-C), respectively. This significant variation of electronic sputtering yield of carbon in different allotropes is discussed from the viewpoint of influence of structure on ion-solid interaction. Structures of the samples are examined by Raman spectroscopy.

  18. Rocket observations of E-region ionization irregularities produced through cross field instability mechanism - Current status

    NASA Astrophysics Data System (ADS)

    Sinha, H. S. S.; Prakash, Satya

    1987-02-01

    The paper reviews the properties of large, medium and small irregularities produced by the cross-field instability mechanism in the equatorial E-region. These studies were mainly carried out with rocket-borne Langmuir probes, resonance probes, proton precession magnetometers and electric field probes flown from an equatorial station Thumba. Results on the regions of occurrence, shapes, amplitudes, spectrum, and direction of propagation of the irregularities are described.

  19. Anomalous Cross-Field Current and Fluctuating Equilibrium of Magnetized Plasmas

    SciTech Connect

    Rypdal, K.; Garcia, O.E.; Paulsen, J.

    1997-09-01

    It is shown by simple physical arguments and fluid simulations that electrostatic flute-mode fluctuations can sustain a substantial cross-field current in addition to mass and energy transport. The simulations show that this current determines essential features of the fluctuating plasma equilibrium, and explain qualitatively the experimental equilibria and the coherent flute-mode structures observed in a simple magnetized torus. {copyright} {ital 1997} {ital The American Physical Society}

  20. I/J Band Low-Cost Crossed-Field Amplifier.

    DTIC Science & Technology

    1981-03-31

    Technical Report DELET-TR-78-2981-F IJ BAND LOW-COST CROSSED-FIELD AMPLIFIER Robe R. Moats D TIC Northrop Corporation Defense Systems Division E LE CT F 600...rtf Commnder US Army Commnications A Electronics Material Readiness Commnd DRSEL-PL- ST 1 DRSEL-MAMP 1 DRSEL-PP-I-PI 1 DRSEL-PA 2 1 Advisory Grop

  1. APPARENT CROSS-FIELD SUPERSLOW PROPAGATION OF MAGNETOHYDRODYNAMIC WAVES IN SOLAR PLASMAS

    SciTech Connect

    Kaneko, T.; Yokoyama, T.; Goossens, M.; Doorsselaere, T. Van; Soler, R.; Terradas, J.; Wright, A. N.

    2015-10-20

    In this paper we show that the phase-mixing of continuum Alfvén waves and/or continuum slow waves in the magnetic structures of the solar atmosphere as, e.g., coronal arcades, can create the illusion of wave propagation across the magnetic field. This phenomenon could be erroneously interpreted as fast magnetosonic waves. The cross-field propagation due to the phase-mixing of continuum waves is apparent because there is no real propagation of energy across the magnetic surfaces. We investigate the continuous Alfvén and slow spectra in two-dimensional (2D) Cartesian equilibrium models with a purely poloidal magnetic field. We show that apparent superslow propagation across the magnetic surfaces in solar coronal structures is a consequence of the existence of continuum Alfvén waves and continuum slow waves that naturally live on those structures and phase-mix as time evolves. The apparent cross-field phase velocity is related to the spatial variation of the local Alfvén/slow frequency across the magnetic surfaces and is slower than the Alfvén/sound velocities for typical coronal conditions. Understanding the nature of the apparent cross-field propagation is important for the correct analysis of numerical simulations and the correct interpretation of observations.

  2. Sputtered silicon nitride coatings for wear protection

    NASA Technical Reports Server (NTRS)

    Grill, A.; Aron, P. R.

    1982-01-01

    Silicon nitride films were deposited by RF sputtering on 304 stainless steel substrates in a planar RF sputtering apparatus. The sputtering was performed from a Si3N4 target in a sputtering atmosphere of argon and nitrogen. The rate of deposition, the composition of the coatings, the surface microhardness and the adhesion of the coatings to the substrates were investigated as a function of the process parameters, such as: substrate target distance, fraction nitrogen in the sputtering atmosphere and sputtering pressure. Silicon rich coating was obtained for fraction nitrogen below 0.2. The rate of deposition decreases continuously with increasing fraction nitrogen and decreasing sputtering pressure. It was found that the adherence of the coatings improves with decreasing sputtering pressure, almost independently of their composition.

  3. Mass dependence of nitride sputtering

    NASA Astrophysics Data System (ADS)

    Elovikov, S. S.; Khrustachev, I. K.; Mosunov, A. S.; Yurasova, V. E.

    2003-08-01

    A molecular dynamics simulation was performed to study the sputtering yield Y for BN, AlN and GaN polycrystals of wurtzite structure as a function of the masses m 1 of bombarding ions with energies from 200 to 2000 eV. A nonmonotonic behavior of the Y ( m 1 ) curve was obtained for the irradiation by low-energy ions, the curve having a maximum with a position being dependent on m 2 / m 1 ( m 2 is the average mass of atoms in a compound). For AlN and GaN the maximum was observed at m 2 / m 1 = 2, and for BN at m 2 / m 1 = 1. The effect of the mass of bombarding ions on the mean energies and energy spectra of sputtered particles, the depth of sputtering origin, and the generation of emitted atoms for nitrides was also investigated and discussed.

  4. Ion beam sputtering of fluoropolymers

    NASA Technical Reports Server (NTRS)

    Sovey, J. S.

    1978-01-01

    Etching and deposition of fluoropolymers are of considerable industrial interest for applications dealing with adhesion, chemical inertness, hydrophobicity, and dielectric properties. This paper describes ion beam sputter processing rates as well as pertinent characteristics of etched targets and films. An argon ion beam source was used to sputter etch and deposit the fluoropolymers PTFE, FEP, and CTFE. Ion beam energy, current density, and target temperature were varied to examine effects on etch and deposition rates. The ion etched fluoropolymers yield cone or spire-like surface structures which vary depending upon the type of polymer, ion beam power density, etch time, and target temperature. Also presented are sputter target and film characteristics which were documented by spectral transmittance measurements, X-ray diffraction, ESCA, and SEM photomicrographs.

  5. Depth profiling of organic films with X-ray photoelectron spectroscopy using C60+ and Ar+ co-sputtering.

    PubMed

    Yu, Bang-Ying; Chen, Ying-Yu; Wang, Wei-Ben; Hsu, Mao-Feng; Tsai, Shu-Ping; Lin, Wei-Chun; Lin, Yu-Chin; Jou, Jwo-Huei; Chu, Chih-Wei; Shyue, Jing-Jong

    2008-05-01

    By sputtering organic films with 10 kV, 10 nA C60+ and 0.2 kV, 300 nA Ar+ ion beams concurrently and analyzing the newly exposed surface with X-ray photoelectron spectroscopy, organic thin-film devices including an organic light-emitting diode and a polymer solar cell with an inverted structure are profiled. The chemical composition and the structure of each layer are preserved and clearly observable. Although C60+ sputtering is proven to be useful for analyzing organic thin-films, thick organic-devices cannot be profiled without the low-energy Ar+ beam co-sputtering due to the nonconstant sputtering rate of the C60+ beam. Various combinations of ion-beam doses are studied in this research. It is found that a high dosage of the Ar+ beam interferes with the C60+ ion beam, and the sputtering rate decreases with increasing the total ion current. The results suggest that the low-energy single-atom projectile can disrupt the atom deposition from the cluster ion beams and greatly extend the application of the cluster ion-sputtering. By achievement of a steady sputtering rate while minimizing the damage accumulation, this research paves the way to profiling soft matter and organic electronics.

  6. Disorder-free sputtering method on graphene

    SciTech Connect

    Qiu Xue Peng; Shin Young Jun; Niu Jing; Kulothungasagaran, Narayanapillai; Kalon, Gopinadhan; Yang, Hyunsoo; Qiu Caiyu; Yu Ting

    2012-09-15

    Deposition of various materials onto graphene without causing any disorder is highly desirable for graphene applications. Especially, sputtering is a versatile technique to deposit various metals and insulators for spintronics, and indium tin oxide to make transparent devices. However, the sputtering process causes damage to graphene because of high energy sputtered atoms. By flipping the substrate and using a high Ar pressure, we demonstrate that the level of damage to graphene can be reduced or eliminated in dc, rf, and reactive sputtering processes.

  7. Faraday screen sputtering on TPX

    SciTech Connect

    Ehst, D.A.

    1994-12-01

    The TPX design stipulates that the ion-cyclotron resonance frequency (ICRF) antenna must have a Faraday screen (FS). The author considers here possible low Z coatings for the screen, as well as sputtering behavior of the Ni and Ti substrates. The theory of rf-induced sputtering has been developed, and he follows those theoretical approaches. The author`s emphasis will be on both impurity generation as a possible source of increased Z{sub eff}, and also on actual erosion-lifetime of the materials under worst case conditions.

  8. Faraday screen sputtering on TPX

    NASA Astrophysics Data System (ADS)

    Ehst, D. A.

    1994-12-01

    The TPX design stipulates that the ion-cyclotron resonance frequency (ICRF) antenna must have a Faraday screen (FS). The author considers here possible low Z coatings for the screen, as well as sputtering behavior of the Ni and Ti substrates. The theory of RF-induced sputtering has been developed, and follows those theoretical approaches. The author's emphasis will be on both impurity generation as a possible source of increased Z(sub eff), and also on actual erosion-lifetime of the materials under worst case conditions.

  9. Modeling target erosion during reactive sputtering

    NASA Astrophysics Data System (ADS)

    Strijckmans, K.; Depla, D.

    2015-03-01

    The influence of the reactive sputter conditions on the racetrack and the sputter profile for an Al/O2 DC reactive sputter system is studied by modeling. The role of redeposition, i.e. the deposition of sputtered material back on the target, is therefore taken into account. The used model RSD2013 is capable of simulating the effect of redeposition on the target condition in a spatial resolved way. Comparison between including and excluding redeposition in the RSD2013 model shows that the in-depth oxidation profile of the target differs. Modeling shows that it is important to distinguish between the formed racetrack, i.e. the erosion depth profile, and the sputter profile. The latter defines the distribution of the sputtered atoms in the vacuum chamber. As the target condition defines the sputter yield, it does determine the racetrack and the sputter profile of the planar circular target. Both the shape of the racetrack and the sputter profile change as function of the redeposition fraction as well as function of the oxygen flow change. Clear asymmetries and narrowing are observed for the racetrack shape. Similar effects are noticed for the sputter profile but to a different extent. Based on this study, the often heard misconception that the racetrack shape defines the distribution of the sputtered atoms during reactive sputtering is proven to be wrong.

  10. Header For Laser Diode

    NASA Technical Reports Server (NTRS)

    Rall, Jonathan A. R.; Spadin, Paul L.

    1990-01-01

    Header designed to contain laser diode. Output combined incoherently with outputs of other laser diodes in grating laser-beam combiner in optical communication system. Provides electrical connections to laser diode, cooling to thermally stabilize laser operation, and optomechanical adjustments that steer and focus laser beam. Range of adjustments provides for correction of worst-case decentering and defocusing of laser beam encountered with laser diodes. Mechanical configuration made simple to promote stability and keep cost low.

  11. Diode and Diode Circuits, a Programmed Text.

    ERIC Educational Resources Information Center

    Balabanian, Norman; Kirwin, Gerald J.

    This programed text on diode and diode circuits was developed under contract with the United States Office of Education as Number 4 in a series of materials for use in an electrical engineering sequence. It is intended as a supplement to a regular text and other instructional material. (DH)

  12. Magnetron-Sputtered Amorphous Metallic Coatings

    NASA Technical Reports Server (NTRS)

    Thakoor, A. P.; Mehra, M.; Khanna, S. K.

    1985-01-01

    Amorphous coatings of refractory metal/metalloid-based alloys deposited by magnetron sputtering provide extraordinary hardness and wear resistance. Sputtering target fabricated by thoroughly mixing powders of tungsten, rhenium, and boron in stated proportions and pressing at 1,200 degrees C and 3,000 lb/in. to second power (21 MPa). Substrate lightly etched by sputtering before deposition, then maintained at bias of - 500 V during initial stages of film growth while target material sputtered onto it. Argon gas at pressure used as carrier gas for sputter deposition. Coatings dense, pinhole-free, extremely smooth, and significantly resistant to chemical corrosion in acidic and neutral aqueous environments.

  13. Laser Diode Ignition (LDI)

    NASA Technical Reports Server (NTRS)

    Kass, William J.; Andrews, Larry A.; Boney, Craig M.; Chow, Weng W.; Clements, James W.; Merson, John A.; Salas, F. Jim; Williams, Randy J.; Hinkle, Lane R.

    1994-01-01

    This paper reviews the status of the Laser Diode Ignition (LDI) program at Sandia National Labs. One watt laser diodes have been characterized for use with a single explosive actuator. Extensive measurements of the effect of electrostatic discharge (ESD) pulses on the laser diode optical output have been made. Characterization of optical fiber and connectors over temperature has been done. Multiple laser diodes have been packaged to ignite multiple explosive devices and an eight element laser diode array has been recently tested by igniting eight explosive devices at predetermined 100 ms intervals.

  14. Laser Diode Ignition (LDI)

    NASA Technical Reports Server (NTRS)

    Kass, William J.; Andrews, Larry A.; Boney, Craig M.; Chow, Weng W.; Clements, James W.; Merson, John A.; Salas, F. Jim; Williams, Randy J.; Hinkle, Lane R.

    1994-01-01

    This paper reviews the status of the Laser Diode Ignition (LDI) program at Sandia National Labs. One watt laser diodes have been characterized for use with a single explosive actuator. Extensive measurements of the effect of electrostatic discharge (ESD) pulses on the laser diode optical output have been made. Characterization of optical fiber and connectors over temperature has been done. Multiple laser diodes have been packaged to ignite multiple explosive devices and an eight element laser diode array has been recently tested by igniting eight explosive devices at predetermined 100 ms intervals.

  15. Lighting with laser diodes

    NASA Astrophysics Data System (ADS)

    Basu, Chandrajit; Meinhardt-Wollweber, Merve; Roth, Bernhard

    2013-08-01

    Contemporary white light-emitting diodes (LEDs) are much more efficient than compact fluorescent lamps and hence are rapidly capturing the market for general illumination. LEDs are also replacing halogen lamps or even newer xenon based lamps in automotive headlamps. Because laser diodes are inherently much brighter and often more efficient than corresponding LEDs, there is great research interest in developing laser diode based illumination systems. Operating at higher current densities and with smaller form factors, laser diodes may outperform LEDs in the future. This article reviews the possibilities and challenges in the integration of visible laser diodes in future illumination systems.

  16. Sputtering technology in solid film lubrication

    NASA Technical Reports Server (NTRS)

    Spalvins, T.

    1978-01-01

    Potential and present sputtering technology is discussed as it applies to the deposition of solid film lubricants particularly MoS2, WS2, and PTFE. Since the sputtered films are very thin, the selection of the sputtering parameters and substrate condition is very critical as reflected by the lubricating properties. It was shown with sputtered MoS2 films that the lubricating characteristics are directly affected by the selected sputtering parameters (power density, pressure, sputter etching, dc-biasing, etc.) and the substrate temperature, chemistry, topography and the environmental conditions during the friction tests. Electron microscopy and other surface sensitive analytical techniques illustrate the resulting changes in sputtered MoS2 film morphology and chemistry which directly influence the film adherence and frictional properties.

  17. A novel sputtering technique: Inductively Coupled Impulse Sputtering (ICIS)

    NASA Astrophysics Data System (ADS)

    Loch, D. A. L.; Ehiasarian, A. P.

    2012-09-01

    Sputtering magnetic materials with magnetron based systems has the disadvantage of field quenching and variation of alloy composition with target erosion. The advantage of eliminating magnetic fields in the chamber is that this enables sputtered particles to move along the electric field more uniformly. Inductively coupled impulse sputtering (ICIS) is a form of high power impulse magnetron sputtering (HIPIMS) without a magnetic field where a high density plasma is produced by a high power radio frequency (RF) coil in order to sputter the target and ionise the metal vapour. In this emerging technology, the effects of power and pressure on the ionisation and deposition process are not known. The setup comprises of a 13.56 MHz pulsed RF coil pulsed with a duty cycle of 25 %. A pulsed DC voltage of 1900 V was applied to the cathode to attract Argon ions and initiate sputtering. Optical emission spectra (OES) for Cu and Ti neutrals and ions at constant pressure show a linear intensity increase for peak RF powers of 500 W - 3400 W and a steep drop of intensity for a power of 4500 W. Argon neutrals show a linear increase for powers of 500 W - 2300 W and a saturation of intensity between 2300 W - 4500 W. The influence of pressure on the process was studied at a constant peak RF power of 2300 W. With increasing pressure the ionisation degree increased. The microstructure of the coatings shows globular growth at 2.95×10-2 mbar and large-grain columnar growth at 1.2×10-1 mbar. Bottom coverage of unbiased vias with a width of 0.360 μm and aspect ratio of 2.5:1 increased from 15 % to 20 % for this pressure range. The current work has shown that the concept of combining a RF powered coil with a magnet-free high voltage pulsed DC powered cathode is feasible and produces very stable plasma. The experiments have shown a significant influence of power and pressure on the plasma and coating microstructure.

  18. Plasma based cross-field particle acceleration with high power microwave

    NASA Astrophysics Data System (ADS)

    Nishida, Y.

    1998-02-01

    Electron acceleration based on the Vp× B acceleration (or the cross-field acceleration) scheme, which has a static magnetic field across the wave propagation direction, is reviewed, specifically the electron linear accelerator using a transverse mode of an EMW is introduced. Penetration and ducting of an intense microwave into overdense plasma are discussed, which show an experimental simulation and precise understanding of the concept of an optical guiding in the laser wakefield accelerator. Coherent radiation of ultrashort microwave pulse by DC-AC radiation conversion scheme has been demonstrated with use of CO 2 laser and array of capacitors. This scheme is based on the mechanism of photon acceleration.

  19. SCALING THEORY FOR CROSS-FIELD TRANSPORT OF COSMIC RAYS IN TURBULENT FIELDS

    SciTech Connect

    Hauff, T.; Jenko, F.; Shalchi, A.; Schlickeiser, R.

    2010-03-10

    The transport of charged particles (e.g., cosmic rays) in astrophysically relevant, turbulent magnetic fields (like they exist, e.g., in the solar wind) is investigated. Generic theoretical models-using concepts and insights developed recently in the context of magnetic confinement fusion research-are applied to the present problem and confirmed by means of numerical simulations. At high energies, a novel transport regime is found, in which the particles decorrelate on a gyro-orbit timescale. Explicit scaling laws for the cross-field diffusivities in various limits are derived.

  20. Cross-field transport of electrons at the magnetic throat in an annular plasma reactor

    NASA Astrophysics Data System (ADS)

    Zhang, Yunchao; Charles, Christine; Boswell, Rod

    2017-01-01

    Cross-field transport of electrons has been studied at the magnetic throat of the annular Chi-Kung reactor. This annular configuration allows the creation of a low pressure argon plasma with two distinct electron heating locations by independently operating a radio-frequency antenna surrounding the outer source tube, or an antenna housed inside the inner source tube. The two antenna cases show opposite variation trends in radial profiles of electron energy probability function, electron density, plasma potential and electron temperature. The momentum and energy transport coefficients are obtained from the electron energy probability functions, and the related electron fluxes follow the path of electron cooling across the magnetic throat.

  1. Influence of oblique magnetic field on electron cross-field transport in a Hall effect thruster

    SciTech Connect

    Miedzik, Jan; Daniłko, Dariusz; Barral, Serge

    2015-04-15

    The effects of the inclination of the magnetic field with respect to the channel walls in a Hall effect thruster are numerically studied with the use of a one-dimensional quasi-neutral Particle-In-Cell model with guiding center approximation of electron motion along magnetic lines. Parametric studies suggest that the incidence angle strongly influences electron transport across the magnetic field. In ion-focusing magnetic topologies, electrons collide predominantly on the side of the magnetic flux tube closer to the anode, thus increasing the electron cross-field drift. The opposite effect is observed in ion-defocussing topology.

  2. Effect of Secondary Electron Emission on Electron Cross-Field Current in ExB Discharges

    NASA Astrophysics Data System (ADS)

    Raitses, Yevgeny; Kaganovich, Igor D.; Khrabrov, Alex V.; Campanell, Michael D.; Tokluoglu, Erinc; Sydorenko, Dmytro; Smolyakov, Andrei

    2012-10-01

    This paper reviews recent experimental, theoretical, and numerical studies of plasma-wall interaction in a weakly collisional magnetized plasma bounded with channel walls made from different materials [1-3]. A low-pressure E x B plasma discharge of the Hall thruster was used to characterize the electron current across the magnetic field and its dependence on the applied voltage and the electron-induced secondary electron emission (SEE) from the channel wall [1]. The presence of a depleted anisotropic electron energy distribution function with beams of secondary electrons was predicted to explain the enhancement of the electron cross-field current observed in experiments. Without the SEE, the electron cross-field transport can be reduced from anomalously high to nearly classical collisional level. The suppression of the SEE was achieved using an engineered carbon-velvet material for the channel walls [3]. Both theoretically and experimentally, it is shown that the electron emission from the walls can limit the maximum achievable electric field in the magnetized plasma. [4pt] [1] Y. Raitses, et al, IEEE Trans. on Plasma Scie. 39, 995 (2011). [0pt] [2] M. D. Campanell, et al, Phys. Rev. Lett. 108, 235001 (2012). [0pt] [3] Y. Raitses, et al, J.Appl. Phys. 99, 036103 (2006).

  3. Vacuum pumping properties of a high voltage 60 Hz crossed field discharge

    NASA Astrophysics Data System (ADS)

    Ames, E. E.

    The principle of electron trapping in a.d.c. Penning discharge is used in the design of standard vacuum pumping equipment. The feasibility of achieving vacuum pumping using high 60 Hz a.c. voltages and permanent magnets arranged to form a crossed field configuration is investigated here. The applications are to use the voltages inherently available in high voltage vacuum insulated power apparatus to cause a vacuum pumping action. This would create a self maintained vacuum without employing an auxiliary vacuum pump. The objective is to maintain a vacuum in the face of outgassing in systems of large surface area over long periods of time, and not necessarily to obtain a fast pump down of the system. Vacuum insulation of underground power cables would require pumps to maintain the vacuum while the cable remains underground for long periods of time. Other applications are in vacuum circuit breaker, lightning arrester, and surge arrester designs. Two devices were designed, built and tested which utilize high 6 Hz a.c. voltages and permanent magnets to generate a crossed field discharge.

  4. ENERGETIC PARTICLE CROSS-FIELD PROPAGATION EARLY IN A SOLAR EVENT

    SciTech Connect

    Laitinen, T.; Dalla, S.; Marsh, M. S.

    2013-08-20

    Solar energetic particles (SEPs) have been observed to easily spread across heliographic longitudes, and the mechanisms responsible for this behavior remain unclear. We use full-orbit simulations of a 10 MeV proton beam in a turbulent magnetic field to study to what extent the spread across the mean field can be described as diffusion early in a particle event. We compare the full-orbit code results to solutions of a Fokker-Planck equation including spatial and pitch angle diffusion, and of one including also propagation of the particles along random-walking magnetic field lines. We find that propagation of the particles along meandering field lines is the key process determining their cross-field spread at 1 AU at the beginning of the simulated event. The mean square displacement of the particles an hour after injection is an order of magnitude larger than that given by the diffusion model, indicating that models employing spatial cross-field diffusion cannot be used to describe early evolution of an SEP event. On the other hand, the diffusion of the particles from their initial field lines is negligible during the first 5 hr, which is consistent with the observations of SEP intensity dropouts. We conclude that modeling SEP events must take into account the particle propagation along meandering field lines for the first 20 hr of the event.

  5. Transport of sputtered particles in capacitive sputter sources

    NASA Astrophysics Data System (ADS)

    Trieschmann, Jan; Mussenbrock, Thomas

    2015-07-01

    The transport of sputtered aluminum inside a multi frequency capacitively coupled plasma chamber is simulated by means of a kinetic test multi-particle approach. A novel consistent set of scattering parameters obtained for a modified variable hard sphere collision model is presented for both argon and aluminum. An angular dependent Thompson energy distribution is fitted to results from Monte Carlo simulations and used for the kinetic simulation of the transport of sputtered aluminum. For the proposed configuration, the transport of sputtered particles is characterized under typical process conditions at a gas pressure of p = 0.5 Pa. It is found that—due to the peculiar geometric conditions—the transport can be understood in a one dimensional picture, governed by the interaction of the imposed and backscattered particle fluxes. It is shown that the precise geometric features play an important role only in proximity to the electrode edges, where the effect of backscattering from the outside chamber volume becomes the governing mechanism.

  6. Double Light-Emitting Diode

    NASA Technical Reports Server (NTRS)

    Johnson, R. L.; Hall, T. C.

    1985-01-01

    Two GaAs light-emitting diodes packaged as single unit offer greater reliability than conventional single-diode package. One diode is primary light source. If it fails, backup diode switched in. Each diode has separate power lead, so either or both switched on or off at same time.

  7. Energy spectrum of sputtered uranium

    NASA Technical Reports Server (NTRS)

    Weller, R. A.; Tombrello, T. A.

    1977-01-01

    The fission track technique for detecting uranium 235 was used in conjunction with a mechanical time-of-flight spectrometer to measure the energy spectrum in the region 1 eV to 1 keV of material sputtered from a 93% enriched U-235 foil by 80 keV Ar-40(+) ions. The spectrum was found to exhibit a peak in the region 2-4 eV and to decrease approximately as E to the -1.77 power for E is approximately greater than 100 eV. The design, construction and resolution of the mechanical spectrometer are discussed and comparisons are made between the data and the predictions of the ramdom collision cascade model of sputtering.

  8. Fabrication of boron sputter targets

    DOEpatents

    Makowiecki, D.M.; McKernan, M.A.

    1995-02-28

    A process is disclosed for fabricating high density boron sputtering targets with sufficient mechanical strength to function reliably at typical magnetron sputtering power densities and at normal process parameters. The process involves the fabrication of a high density boron monolithe by hot isostatically compacting high purity (99.9%) boron powder, machining the boron monolithe into the final dimensions, and brazing the finished boron piece to a matching boron carbide (B{sub 4}C) piece, by placing aluminum foil there between and applying pressure and heat in a vacuum. An alternative is the application of aluminum metallization to the back of the boron monolithe by vacuum deposition. Also, a titanium based vacuum braze alloy can be used in place of the aluminum foil. 7 figs.

  9. Fabrication of boron sputter targets

    DOEpatents

    Makowiecki, Daniel M.; McKernan, Mark A.

    1995-01-01

    A process for fabricating high density boron sputtering targets with sufficient mechanical strength to function reliably at typical magnetron sputtering power densities and at normal process parameters. The process involves the fabrication of a high density boron monolithe by hot isostatically compacting high purity (99.9%) boron powder, machining the boron monolithe into the final dimensions, and brazing the finished boron piece to a matching boron carbide (B.sub.4 C) piece, by placing aluminum foil there between and applying pressure and heat in a vacuum. An alternative is the application of aluminum metallization to the back of the boron monolithe by vacuum deposition. Also, a titanium based vacuum braze alloy can be used in place of the aluminum foil.

  10. In-situ sputtering apparatus

    DOEpatents

    Erickson, Mark R.; Poole, Henry J.; Custer, III, Arthur W.; Hershcovitch, Ady

    2015-06-09

    A sputtering apparatus that includes at least a target presented as an inner surface of a confinement structure, the inner surface of the confinement structure is preferably an internal wall of a circular tube. A cathode is disposed adjacent the internal wall of the circular tube. The cathode preferably provides a hollow core, within which a magnetron is disposed. Preferably, an actuator is attached to the magnetron, wherein a position of the magnetron within the hollow core is altered upon activation of the actuator. Additionally, a carriage supporting the cathode and communicating with the target is preferably provided, and a cable bundle interacting with the cathode and linked to a cable bundle take up mechanism provided power and coolant to the cathode, magnetron, actuator and an anode of the sputtering apparatus.

  11. Sputtering Holes with Ion Beamlets

    NASA Technical Reports Server (NTRS)

    Byers, D. C.; Banks, B. A.

    1974-01-01

    Ion beamlets of predetermined configurations are formed by shaped apertures in the screen grid of an ion thruster having a double grid accelerator system. A plate is placed downstream from the screen grid holes and attached to the accelerator grid. When the ion thruster is operated holes having the configuration of the beamlets formed by the screen grid are sputtered through the plate at the accelerator grid.

  12. Mercury Cadmium Telluride Sputtering Research.

    DTIC Science & Technology

    1982-08-28

    Material Research Corporation 8800 sputtering system used to deposit the (Hhl.x,Cdx)Te thin films by the triode-ode is shown in Fig. 1-1.()* rotating...by Dr. Comely with Dr. Esther Krikorian of the Aerospace Corporation , El Segundo, California. 28) Ferrar, R.H., Gillham, C.J., Bartlett, B., Oualch, M...Chen. 14, 44 (1975). 44) Belov, V., Personal Commnication of Dr. Cornely with Dr. Valery Belov, Vice President of Engineering, Infrared Associates, Now

  13. Mercury Cadmium Telluride Sputtering Research.

    DTIC Science & Technology

    1981-06-01

    the sixteenth per cubic cm range. Similar results wereobtained using CdTeand Si substrates and for other compositions. For films with 0.18 CdTe mole...on silicon substrates were reproducible for the sputtering parameters used . Recent research has indicated ways to improve these as-deDosited film...square substrate) only one or two CdTe substrates were used in each deposition run. The main deposition parameters were: r.f. power applied to the target

  14. Bypass diode integration

    NASA Technical Reports Server (NTRS)

    Shepard, N. F., Jr.

    1981-01-01

    Protective bypass diodes and mounting configurations which are applicable for use with photovoltaic modules having power dissipation requirements in the 5 to 50 watt range were investigated. Using PN silicon and Schottky diode characterization data on packaged diodes and diode chips, typical diodes were selected as representative for each range of current carrying capacity, an appropriate heat dissipating mounting concept along with its environmental enclosure was defined, and a thermal analysis relating junction temperature as a function of power dissipation was performed. In addition, the heat dissipating mounting device dimensions were varied to determine the effect on junction temperature. The results of the analysis are presented as a set of curves indicating junction temperature as a function of power dissipation for each diode package.

  15. Etalon laser diode

    SciTech Connect

    Allen, L.B.; Koenig, H.G.; Rice, R.R.

    1981-08-18

    A laser diode is disclosed that is suitable for integrated and fiber optic applications requiring single transverse and single longitudinal mode operation. The single transverse mode is provided by making a gallium arsenide double heterostructural laser diode with a narrow stripe width and a relatively long length. The single longitudinal mode operation is provided by cracking the diode transverse to the stripe at one or more locations to form internal etalons in the laser cavity.

  16. Collision-spike sputtering of Au nanoparticles

    SciTech Connect

    Sandoval, Luis; Urbassek, Herbert M.

    2015-08-06

    Ion irradiation of nanoparticles leads to enhanced sputter yields if the nanoparticle size is of the order of the ion penetration depth. While this feature is reasonably well understood for collision-cascade sputtering, we explore it in the regime of collision-spike sputtering using molecular-dynamics simulation. For the particular case of 200-keV Xe bombardment of Au particles, we show that collision spikes lead to abundant sputtering with an average yield of 397 ± 121 atoms compared to only 116 ± 48 atoms for a bulk Au target. Only around 31 % of the impact energy remains in the nanoparticles after impact; the remainder is transported away by the transmitted projectile and the ejecta. As a result, the sputter yield of supported nanoparticles is estimated to be around 80 % of that of free nanoparticles due to the suppression of forward sputtering.

  17. Collision-spike sputtering of Au nanoparticles

    DOE PAGES

    Sandoval, Luis; Urbassek, Herbert M.

    2015-08-06

    Ion irradiation of nanoparticles leads to enhanced sputter yields if the nanoparticle size is of the order of the ion penetration depth. While this feature is reasonably well understood for collision-cascade sputtering, we explore it in the regime of collision-spike sputtering using molecular-dynamics simulation. For the particular case of 200-keV Xe bombardment of Au particles, we show that collision spikes lead to abundant sputtering with an average yield of 397 ± 121 atoms compared to only 116 ± 48 atoms for a bulk Au target. Only around 31 % of the impact energy remains in the nanoparticles after impact; themore » remainder is transported away by the transmitted projectile and the ejecta. As a result, the sputter yield of supported nanoparticles is estimated to be around 80 % of that of free nanoparticles due to the suppression of forward sputtering.« less

  18. Sputtering and ion plating for aerospace applications

    NASA Technical Reports Server (NTRS)

    Spalvins, T.

    1981-01-01

    Sputtering and ion plating technologies are reviewed in terms of their potential and present uses in the aerospace industry. Sputtering offers great universality and flexibility in depositing any material or in the synthesis of new ones. The sputter deposition process has two areas of interest: thin film and fabrication technology. Thin film sputtering technology is primarily used for aerospace mechanical components to reduce friction, wear, erosion, corrosion, high temperature oxidation, diffusion and fatigue, and also to sputter-construct temperature and strain sensors for aircraft engines. Sputter fabrication is used in intricate aircraft component manufacturing. Ion plating applications are discussed in terms of the high energy evaporant flux and the high throwing power. Excellent adherence and 3-dimensional coverage are the primary attributes of this technology.

  19. Sputtering and ion plating for aerospace applications

    NASA Technical Reports Server (NTRS)

    Spalvins, T.

    1981-01-01

    Sputtering and ion plating technologies are reviewed in terms of their potential and present uses in the aerospace industry. Sputtering offers great universality and flexibility in depositing any material or in the synthesis of new ones. The sputter deposition process has two areas of interest: thin film and fabrication technology. Thin film sputtering technology is primarily used for aerospace mechanical components to reduce friction, wear, erosion, corrosion, high temperature oxidation, diffusion and fatigue, and also to sputter-construct temperature and strain sensors for aircraft engines. Sputter fabrication is used in intricate aircraft component manufacturing. Ion plating applications are discussed in terms of the high energy evaporant flux and the high throwing power. Excellent adherence and 3 dimensional coverage are the primary attributes of this technology.

  20. Collision-spike Sputtering of Au Nanoparticles.

    PubMed

    Sandoval, Luis; Urbassek, Herbert M

    2015-12-01

    Ion irradiation of nanoparticles leads to enhanced sputter yields if the nanoparticle size is of the order of the ion penetration depth. While this feature is reasonably well understood for collision-cascade sputtering, we explore it in the regime of collision-spike sputtering using molecular-dynamics simulation. For the particular case of 200-keV Xe bombardment of Au particles, we show that collision spikes lead to abundant sputtering with an average yield of 397 ± 121 atoms compared to only 116 ± 48 atoms for a bulk Au target. Only around 31 % of the impact energy remains in the nanoparticles after impact; the remainder is transported away by the transmitted projectile and the ejecta. The sputter yield of supported nanoparticles is estimated to be around 80 % of that of free nanoparticles due to the suppression of forward sputtering.

  1. Coaxial foilless diode

    SciTech Connect

    Kong, Long; Liu, QingXiang; Li, XiangQiang; Wang, ShaoMeng

    2014-05-15

    A kind of coaxial foilless diode is proposed in this paper, with the structure model and operating principle of the diode are given. The current-voltage relation of the coaxial foilless diode and the effects of structure parameters on the relation are studied by simulation. By solving the electron motion equation, the beam deviation characteristic in the presence of external magnetic field in transmission process is analyzed, and the relationship between transverse misalignment with diode parameters is obtained. These results should be of interest to the area of generation and propagation of radial beam for application of generating high power microwaves.

  2. HEAT DIODE CONVERTER

    DTIC Science & Technology

    DIODES, * ELECTRIC POWER PRODUCTION, *REFRACTORY MATERIALS, *THERMIONIC EMISSION, CESIUM, COPPER, DISCHARGE TUBES, ELECTRONS, EVAPORATION, MOLYBDENUM...PLASMAS(PHYSICS), POWER SUPPLIES, REFLECTION, THERMAL CONDUCTIVITY, THERMIONIC CONVERTERS , VAPORS.

  3. FISSION HEAT DIODE CONVERTER

    DTIC Science & Technology

    CESIUM, *DIODES, * ELECTRIC POWER PRODUCTION, ADSORPTION, AUXILIARY POWER PLANTS, ELECTRONS, OSCILLATION, PLASMAS(PHYSICS), POWER SUPPLIES...SCATTERING, SOURCES, SPACECRAFT, THERMAL CONDUCTIVITY, THERMIONIC CONVERTERS , THERMIONIC EMISSION, TUNGSTEN, VAPORS

  4. Development of sputtered techniques for thrust chambers

    NASA Technical Reports Server (NTRS)

    Mullaly, J. R.; Allard, P. A.

    1979-01-01

    The 0.152 cm thick sputtered and copper deposits were electron beam welded to wrought copper. Tensile specimens were machined from the weld assemblies and tested at room temperature. Tensile strength approached the strength of wrought material. Elongations up to 25% were measured. Sputtered aluminum was used to fill 0.157 cm wide by 0.127 cm deep grooves in thrust chamber spool piece liners. The liners were closed out by sputtering copper from post and hollow cathodes.

  5. Mercury Cadmium Telluride Sputtered Target Research.

    DTIC Science & Technology

    1982-06-29

    ShirnlU in 1967 to describe the altered layer formation in the binary alloy NiCr . This model assumes an infinitesimally thin layer being sputter ...AD-AL7 456 NEW JERSEY INST OF TECH NEWARK DEPT OP ELECTRICAL EN-ETC FIG 13/8 MERCURY CADMIUM TELLURIDE SPUTTERED TARGET RESEARCH( U) JUN 82 R H...MERCURY CADMIUM TELLURIDE SPUTTERED TARGET RESEARCH TYPE OF REPORT (TECHNICAL, FINAL, ETC.) FINAL TECHNICAL REPORT AUTHOR (S) ROY H. CORNELY DATE JUNE 29

  6. Sputtered iridium oxide for stimulation electrode coatings.

    PubMed

    Mokwa, Wilfried; Wessling, Boerge; Schnakenberg, Uwe

    2007-01-01

    This work deals with the reactive RF-powered sputter deposition of iridium oxide for use as the active stimulation layer in functional medical implants. The oxygen gettered by the growing films is determined by an approach based on generic curves. Films deposited at different stages of oxygen integration show strong differences in electrochemical behaviour, caused by different morphologies. The dependence of electrochemical activity on morphology is further illustrated by RF sputtering onto heated substrates, as well as DC sputtering onto cold substrates.

  7. Reactively sputtered thin film photovoltaic devices

    NASA Technical Reports Server (NTRS)

    Hsieh, E. J.

    1975-01-01

    The feasibility of a reactively sputtered thin film CdS - Cu2S solar cell is proven. Identification of the reactively sputtered Cu2S film is made by X-ray diffractometer and spectro-transmission measurements. Because of its simplicity, economical use of material, and high yield, the reactive sputtering process promises to be a low cost method for producing CdS - Cu2S solar cells.

  8. Local and global effects of the cross-field current instability

    NASA Technical Reports Server (NTRS)

    Lui, A. T. Y.

    1996-01-01

    The cross-field current instability (CCI) was proposed elsewhere as a plausible mechanism for the initiation and intensification of substorm expansions. This instability encompasses the modified two stream, the ion-Weibel and the lower hybrid drift modes. The work carried out in relation to this instability and its local and global effects is reviewed. Predicted local effects include current reduction, particle acceleration, the excitation of oblique whistlers and lower hybrid drift waves, and the breakdown of the frozen-in-field condition through anomalous dissipation. The predicted global effects of CCI include the offset of force equilibrium and the generation of field aligned currents at the disruption site, which allow the efficient large scale transportation of mass, momentum and energy within the magnetosphere.

  9. Electron Cross-field Transport in a Miniaturized Cylindrical Hall Thruster

    SciTech Connect

    Smirnov Artem, Raitses Yevgeny, Fisch Nathaniel J

    2005-10-14

    Conventional annular Hall thrusters become inefficient when scaled to low power. Cylindrical Hall thrusters, which have lower surface-to-volume ratio, are more promising for scaling down. They presently exhibit performance comparable with conventional annular Hall thrusters. The present paper gives a review of the experimental and numerical investigations of electron crossfield transport in the 2.6 cm miniaturized cylindrical Hall thruster (100 W power level). We show that, in order to explain the discharge current observed for the typical operating conditions, the electron anomalous collision frequency {nu}{sub b} has to be on the order of the Bohm value, {nu}{sub B} {approx} {omega}{sub c}/16. The contribution of electron-wall collisions to cross-field transport is found to be insignificant. The optimal regimes of thruster operation at low background pressure (below 10{sup -5} Torr) in the vacuum tank appear to be different from those at higher pressure ({approx} 10{sup -4} Torr).

  10. Plasma heating at collisionless shocks due to the kinetic cross-field streaming instability

    NASA Technical Reports Server (NTRS)

    Winske, D.; Quest, K. B.; Tanaka, M.; Wu, C. S.

    1985-01-01

    Heating at collisionless shocks due to the kinetic cross-field streaming instability, which is the finite beta (ratio of plasma to magnetic pressure) extension of the modified two stream instability, is studied. Heating rates are derived from quasi-linear theory and compared with results from particle simulations to show that electron heating relative to ion heating and heating parallel to the magnetic field relative to perpendicular heating for both the electrons and ions increase with beta. The simulations suggest that electron dynamics determine the saturation level of the instability, which is manifested by the formation of a flattop electron distribution parallel to the magnetic field. As a result, both the saturation levels of the fluctuations and the heating rates decrease sharply with beta. Applications of these results to plasma heating in simulations of shocks and the earth's bow shock are described.

  11. Thermal effects and space-charge limited transition in crossed-field devices

    SciTech Connect

    Marini, Samuel; Rizzato, Felipe B.; Pakter, Renato

    2014-08-15

    A fully kinetic model for the electron flow in a crossed field device is derived and used to determine the system stationary states. It is found that for low injection temperatures, there is a simultaneous presence of distinct stationary solutions and an abrupt transition between accelerating and space-charge limited regimes. On the other hand, for high injection temperatures, there is only a single stationary solution branch and the change between the regimes becomes continuous. For intermediate temperatures, it is then identified a critical point that separates the abrupt and continuous behaviors. It is also investigated how intrinsic space-charge oscillations may drive stationary states unstable in certain parameter regimes. The results are verified with N-particle self-consistent simulations.

  12. Sputtering Threshold Energies of Heavy Ions

    NASA Technical Reports Server (NTRS)

    Mantenieks, Maris A.

    1999-01-01

    Sputter erosion in ion thrusters has been measured in lifetests at discharge voltages as low as 25 V. Thruster operation at this discharge voltage results in component erosion rates sufficiently low to satisfy most mission requirements. It has been recognized that most of the internal sputtering in ion thrusters is done by doubly charged ions. Knowledge of the sputtering threshold voltage of a xenon molybdenum system would be beneficial in understanding the sputtering process as well as making more accurate calculations of the sputtering rates of ion thruster components. Sputtering threshold energies calculated from various formulations found in the literature results in values ranging from 28 to 200 eV. It is evident that some of these formulations cannot be relied upon to provide sputtering thresholds with any degree of accuracy. This paper re-examines the threshold energies measurements made in the early sixties by Askerov and Sena, and Stuart and Wehner. The threshold voltages as derived by Askerov and au have been reevaluated by using a different extrapolation method of sputter yields at low ion energies. The resulting threshold energies are in general similar to those measured by Stuart and Wehner. An empirical relationship is derived,for mercury and xenon ions for the ratio of the sputtering threshold energy to the sublimation energy as a function of the ratio of target to ion atomic mass.

  13. Reduction of residual gas in a sputtering system by auxiliary sputter of rare-earth metal

    NASA Astrophysics Data System (ADS)

    Li, Dejie

    2002-01-01

    In film deposition by sputtering, the oxidation and nitrification of the sputtered material lead to degradation of film quality, particularly with respect to metal sulfide films. We propose to use auxiliary sputtering as a method to produce a fresh film of rare-earth metal, usually dysprosium (Dy), that absorbs the active gases in a sputtering system, greatly reducing the background pressure and protecting the film from oxidation and nitrification effectively. The influence of the auxiliary sputtering power consumption, sputtering time, and medium gas pressure on the background pressure in the vacuum chamber is investigated in detail. If the auxiliary sputtering power exceeds 120 W and the sputtering time is more than 4 min, the background pressure is only one fourth of the ultimate pressure pumped by an oil diffusion pump. The absorption activity of the sputtered Dy film continues at least an hour after completion of the auxiliary sputter. Applied to film deposition of Ti and ZnS, this technique has been proven to be effective. For the Ti film, the total content of N and O is reduced from 45% to 20% when the auxiliary sputtering power of Dy is 120 W, and the sputtering time is 20 min. In the case of ZnS, the content of O is reduced from 8% to 2%.

  14. Effects of Anomalous Electron Cross-Field Transport in a Low Temperature Magnetized Plasma

    NASA Astrophysics Data System (ADS)

    Raitses, Yevgeny

    2014-10-01

    The application of the magnetic field in a low pressure plasma can cause a spatial separation of low and high energy electrons. This so-called magnetic filter effect is used for many plasma applications, including ion and neutral beam sources, plasma processing of semiconductors and nanomaterials, and plasma thrusters. In spite of successful practical applications, the magnetic filter effect is not well understood. In this work, we explore this effect by characterizing the electron and ion energy distribution functions in a plasma column with crossed electric and magnetic fields. Experimental results revealed a strong dependence of spatial variations of plasma properties on the gas pressure. For xenon and argon gases, below ~ 1 mtorr, the increase of the magnetic field leads to a more uniform profile of the electron temperature. This surprising result is due to anomalously high electron cross-field transport that causes mixing of hot and cold electrons. High-speed imaging and probe measurements revealed a coherent structure rotating in E cross B direction with frequency of a few kHz. Theory and simulations describing this rotating structure has been developed and points to ionization and electrostatic instabilities as their possible cause. Similar to spoke oscillations reported for Hall thrusters, this rotating structure conducts the large fraction of the cross-field current. The use of segmented electrodes with an electrical feedback control is shown to mitigate these oscillations. Finally, a new feature of the spoke phenomenon that has been discovered, namely a sensitive dependence of the rotating oscillations on the gas pressure, can be important for many applications. This work was supported by DOE Contract DE-AC02-09CH11466.

  15. Significant improvement of GaN crystal quality with ex-situ sputtered AlN nucleation layers

    NASA Astrophysics Data System (ADS)

    Chen, Shuo-Wei; Yang, Young; Wen, Wei-Chih; Li, Heng; Lu, Tien-Chang

    2016-03-01

    Ex-situ sputtered AlN nucleation layer has been demonstrated effective to significantly improve crystal quality and electrical properties of GaN epitaxy layers for GaN based Light-emitting diodes (LEDs). In this report, we have successfully reduced X-ray (102) FWHM from 240 to 110 arcsec, and (002) FWHM from 230 to 101 arcsec. In addition, reverse-bias voltage (Vr) increased around 20% with the sputtered AlN nucleation layer. Furthermore, output power of LEDs grown on sputtered AlN nucleation layer can be improved around 4.0% compared with LEDs which is with conventional GaN nucleation layer on pattern sapphire substrate (PSS).

  16. Room-temperature-processed flexible n-InGaZnO/p-Cu2O heterojunction diodes and high-frequency diode rectifiers

    NASA Astrophysics Data System (ADS)

    Chen, Wei-Chung; Hsu, Po-Ching; Chien, Chih-Wei; Chang, Kuei-Ming; Hsu, Chao-Jui; Chang, Ching-Hsiang; Lee, Wei-Kai; Chou, Wen-Fang; Hsieh, Hsing-Hung; Wu, Chung-Chih

    2014-09-01

    In this work, we report successful implementation of room-temperature-processed flexible n-InGaZnO/p-Cu2O heterojunction diodes on polyethylene naphthalate (PEN) plastic substrates using the sputtering technique. Using n-type InGaZnO and p-type Cu2O films deposited by sputtering at room temperature, flexible n-InGaZnO/p-Cu2O heterojunction diodes were successfully fabricated on PEN plastic substrates. The didoes on PEN substrates exhibited a low apparent turn-on voltage of 0.44 V, a high rectification ratio of up to 3.4 × 104 at ±1.2 V, a high forward current of 1 A cm-2 around 1 V and a decent ideality factor of 1.4, similar to the characteristics of n-InGaZnO/p-Cu2O diodes fabricated on glass substrates. The characterization of the frequency response of the room-temperature-processed flexible n-InGaZnO/p-Cu2O heterojunction diode rectifiers indicated that they are capable of high-frequency operation up to 27 MHz, sufficient for high-frequency (13.56 MHz) applications. Preliminary bending tests on diode characteristics and rectifier frequency responses indicate their promise for applications in flexible electronics.

  17. Vortex diode jet

    DOEpatents

    Houck, Edward D.

    1994-01-01

    A fluid transfer system that combines a vortex diode with a jet ejector to transfer liquid from one tank to a second tank by a gas pressurization method having no moving mechanical parts in the fluid system. The vortex diode is a device that has a high resistance to flow in one direction and a low resistance to flow in the other.

  18. Velocimetry with diode lasers

    NASA Astrophysics Data System (ADS)

    de Mul, F. F. M.; Jentink, H. W.; Koelink, M.; Greve, J.; Aarnoudse, J. G.

    The history of the application of diode lasers in velocimetry is reviewed. Some problems arising when using those lasers, e.g., mode hopping and wavelength shifts caused by temperature effects, are discussed, together with coherence effects encountered with diode lasers. The application in dual-beam velocimetry, in direct-contact velocimetry and in velocimetry using self-mixing will be discussed.

  19. Diodes stabilize LED output

    NASA Technical Reports Server (NTRS)

    Deters, R. A.

    1977-01-01

    Small-signal diodes are placed in series with light-emitting diodes (LED's) to stabilize LED output against temperature fluctuations. Simple inexpensive method compensates for thermal fluctuations over a broad temperature range. Requiring few components, technique is particularly useful where circuit-board space is limited.

  20. Diodes stabilize LED output

    NASA Technical Reports Server (NTRS)

    Deters, R. A.

    1977-01-01

    Small-signal diodes are placed in series with light-emitting diodes (LED's) to stabilize LED output against temperature fluctuations. Simple inexpensive method compensates for thermal fluctuations over a broad temperature range. Requiring few components, technique is particularly useful where circuit-board space is limited.

  1. Si nanocrystal p-i-n diodes fabricated on quartz substrates for third generation solar cell applications

    NASA Astrophysics Data System (ADS)

    Perez-Wurfl, Ivan; Hao, Xiaojing; Gentle, Angus; Kim, Dong-Ho; Conibeer, Gavin; Green, Martin. A.

    2009-10-01

    We fabricated p-i-n diodes by sputtering alternating layers of silicon dioxide and silicon rich oxide with a nominal atomic ratio O/Si=0.7 onto quartz substrates with in situ boron for p-type and phosphorus for n-type doping. After crystallization, dark and illuminated I-V characteristics show a diode behavior with an open circuit voltage of 373 mV. Due to the thinness of the layers and their corresponding high resistivity, lateral current flow results in severe current crowding. This effect is taken into account when extracting the electronic bandgap based on temperature dependent diode I-V measurements.

  2. Development of sputtered techniques for thrust chambers. [coolant passage closing by triode sputtering

    NASA Technical Reports Server (NTRS)

    Mullaly, J. R.; Hecht, R. J.; Broch, J. W.; Allard, P. A.

    1976-01-01

    Procedures for closing out coolant passages in regeneratively cooled thrust chambers by triode sputtering, using post and hollow Cu-0.15 percent Zr cathodes are described. The effects of aluminum composite filler materials, substrate preparation, sputter cleaning, substrate bias current density and system geometry on closeout layer bond strength and structure are evaluated. High strength closeout layers were sputtered over aluminum fillers. The tensile strength and microstructure of continuously sputtered Cu-0.15 percent Zr deposits were determined. These continuous sputtered deposits were as thick as 0.75 cm. Tensile strengths were consistently twice as great as the strength of the material in wrought form.

  3. Dust Growth by RF Sputtering

    SciTech Connect

    Churton, B.; Samarian, A. A.; Coueedel, L.

    2008-09-07

    The effect of the dust particle growth by RF sputtering on glow discharge has been investigated. It has been found that the growth of dust particles modifies the electrical characteristics of the discharge. In particularly, the absolute value of the self-bias voltage decreases during the particle growth due to the electron losses on the dust particles. To find the correlation between the dust growth and the self bias evolution, dust particles have been collected at different times. The dust particle growth rate is found to be linear.

  4. Sputtered amorphous silicon solar cells. Quarterly report No. 2, October 22, 1980-January 22, 1981

    SciTech Connect

    Moustakas, T.D.; Morel, D.L.; Wronski, C.R.

    1981-01-01

    The mechanism of hydrogen incorporation during the film growth was investigated through hydrogen content studies. The data are consistent with a kinetic model of hydrogen incorporation. The hole mobility-lifetime products were measured on a-SiH/sub x//metal Schottky barrier structures with a new method utilizing optical absorption, collection efficiency, and capacitance voltage measurements. The diode properties of reactively sputtered hydrogenated amorphous silicon Schottky barrier structures (a-SiH/sub x//Pt) were investigated as a function of hydrogen content. The data are interpreted in terms of hydrogen modification of the valence band edge and interfacial oxide effects. The fabrication by the method of sputtering of P-I-N/ITO solar cell structures is reported. (MHR)

  5. Impact of cross-field motion on ablation of high-Z dust in fusion edge plasmas

    NASA Astrophysics Data System (ADS)

    Smirnov, R. D.; Krasheninnikov, S. I.

    2017-07-01

    The impact of cross-field motion of high-Z dust grains on their shielding by ablation cloud in edge plasmas of tokamaks is analyzed. The modification of the existing high-Z dust shielding theory is developed, which takes the dust motion effects into account. It is shown that the cross-field motion can lead to a large factor increase of the dust ablation rate, as compared to the previous model. It is also shown that the motion effects take place when the dust cross-field velocity exceeds a threshold value. The dependencies of the dust ablation flux on the dust velocity and of the threshold velocity on the dust size and the ambient plasma temperature are obtained.

  6. Impact of cross-field motion on ablation of high-Z dust in fusion edge plasmas

    DOE PAGES

    Smirnov, R. D.; Krasheninnikov, S. I.

    2017-07-05

    The impact of cross-field motion of high-Z dust grains on their shielding by ablation cloud in edge plasmas of tokamaks is analyzed. The modification of the existing high-Z dust shielding theory is developed, which takes the dust motion effects into account. We show that the cross-field motion can lead to a large factor increase of the dust ablation rate, as compared to the previous model. It is also shown that the motion effects take place when the dust cross-field velocity exceeds a threshold value. We also obtain the dependencies of the dust ablation flux on the dust velocity and ofmore » the threshold velocity on the dust size and the ambient plasma temperature.« less

  7. Sputtering performance of the TFCX limiter

    SciTech Connect

    Brooks, J.N.

    1984-09-01

    The sputtering performance of the proposed TFCX pumped limiter was analyzed using the REDEP computer code. Erosion, redeposition, surface shape and heat flux changes with time, and plasma contamination issues were examined. A carbon coated limiter was found to give acceptable sputtering performance over the TFCX lifetime if, and only if, acceptable redeposition properties of carbon are obtained.

  8. Sputter metalization of Wolter type optical elements

    NASA Technical Reports Server (NTRS)

    Ledger, A. M.

    1977-01-01

    An analytical task showed that the coating thickness distribution for both internal and external optical elements coated using either electron beam or sputter sources can be made uniform and will not affect the surface figure of coated elements. Also, sputtered samples of nickel, molybdenum, iridium and ruthenium deposited onto both hot and cold substrates showed excellent adhesion.

  9. REACTIVE SPUTTER DEPOSITION OF CHROMIUM NITRIDE COATINGS

    EPA Science Inventory

    The effect of substrate temperature and sputtering gas compositon on the structure and properties of chromium-chromium nitride films deposited on C-1040 steel using r.f. magnetron sputter deposition was investigated. X-ray diffraction analysis was used to determine the structure ...

  10. REACTIVE SPUTTER DEPOSITION OF CHROMIUM NITRIDE COATINGS

    EPA Science Inventory

    The effect of substrate temperature and sputtering gas compositon on the structure and properties of chromium-chromium nitride films deposited on C-1040 steel using r.f. magnetron sputter deposition was investigated. X-ray diffraction analysis was used to determine the structure ...

  11. Destruction of dirty ice mantles by sputtering

    NASA Technical Reports Server (NTRS)

    Aannestad, P. A.

    1973-01-01

    Dirty ice mantles are destroyed efficiently by sputtering of He atoms when clouds encounter shock velocities greater than 13-15 km/sec. Destruction due to grain-grain collisions is found to be about .001 times less efficient. Sputtering in the hot intercloud medium should make intercloud grains smaller than cloud grains.

  12. Confined ion beam sputtering device and method

    DOEpatents

    Sharp, Donald J.

    1988-01-01

    A hollow cylindrical target, lined internally with a sputter deposit material and open at both ends, surrounds a substrate on which sputtered deposition is to be obtained. An ion beam received through either one or both ends of the open cylindrical target is forced by a negative bias applied to the target to diverge so that ions impinge at acute angles at different points of the cylindrical target surface. The ion impingement results in a radially inward and downstream directed flux of sputter deposit particles that are received by the substrate. A positive bias applied to the substrate enhances divergence of the approaching ion beams to generate a higher sputtered deposition flux rate. Alternatively, a negative bias applied to the substrate induces the core portion of the ion beams to reach the substrate and provide ion polishing of the sputtered deposit thereon.

  13. Confined ion beam sputtering device and method

    DOEpatents

    Sharp, D.J.

    1986-03-25

    A hollow cylindrical target, lined internally with a sputter deposit material and open at both ends, surrounds a substrate on which sputtered deposition is to be obtained. An ion beam received through either one or both ends of the open cylindrical target is forced by a negative bias applied to the target to diverge so that ions impinge at acute angles at different points of the cylindrical target surface. The ion impingement results in a radially inward and downstream directed flux of sputter deposit particles that are received by the substrate. A positive bias applied to the substrate enhances divergence of the approaching ion beams to generate a higher sputtered deposition flux rate. Alternatively, a negative bias applied to the substrate induces the core portion of the ion beams to reach the substrate and provide ion polishing of the sputtered deposit thereon.

  14. Measurements of beryllium sputtering yields at JET

    NASA Astrophysics Data System (ADS)

    Jet-Efda Contributors Stamp, M. F.; Krieger, K.; Brezinsek, S.

    2011-08-01

    The lifetime of the beryllium first wall in ITER will depend on erosion and redeposition processes. The physical sputtering yields for beryllium (both deuterium on beryllium (Be) and Be on Be) are of crucial importance since they drive the erosion process. Literature values of experimental sputtering yields show an order of magnitude variation so predictive modelling of ITER wall lifetimes has large uncertainty. We have reviewed the old beryllium yield experiments on JET and used current beryllium atomic data to produce revised beryllium sputtering yields. These experimental measurements have been compared with a simple physical sputtering model based on TRIM.SP beryllium yield data. Fair agreement is seen for beryllium yields from a clean beryllium limiter. However the yield on a beryllium divertor tile (with C/Be co-deposits) shows poor agreement at low electron temperatures indicating that the effect of the higher sputtering threshold for beryllium carbide is important.

  15. Study of breakdown voltage of indium-gallium-zinc-oxide-based Schottky diode

    SciTech Connect

    Xin, Qian; Yan, Linlong; Luo, Yi; Song, Aimin

    2015-03-16

    In contrast to the intensive studies on thin-film transistors based on indium gallium zinc oxide (IGZO), the research on IGZO-based diodes is still very limited, particularly on their behavior and stability under high bias voltages. Our experiments reveal a sensitive dependence of the breakdown voltage of IGZO Schottky diodes on the anode metal and the IGZO film thickness. Devices with an Au anode are found to breakdown easily at a reverse bias as low as −2.5 V, while the devices with a Pd anode and a 200-nm, fully depleted IGZO layer have survived up to −15 V. All diodes are fabricated by radio-frequency magnetron sputtering at room temperature without any thermal treatment, yet showing an ideality factor as low as 1.14, showing the possibility of achieving high-performance Schottky diodes on flexible plastic substrate.

  16. Sputter Deposition of Metallic Sponges

    SciTech Connect

    Jankowski, A F; Hayes, J P

    2002-01-18

    Metallic films are grown with a sponge-like morphology in the as-deposited condition using planar magnetron sputtering. The morphology of the deposit is characterized by metallic continuity in three dimensions with continuous porosity on the sub-micron scale. The stabilization of the metallic sponge is directly correlated with a limited range for the sputter deposition parameters of working gas pressure and substrate temperature. This sponge-like morphology augments the features as generally understood in the classic zone models of growth for physical vapor deposits. Nickel coatings are deposited with working gas pressures up to 4 Pa and for substrate temperatures up to 1100 K. The morphology of the deposits is examined in plan and in cross-section with scanning electron microscopy. The parametric range of gas pressure and substrate temperature (relative to absolute melt point) for the deposition processing under which the metallic sponges are produced appear universal for many metals, as for example, including gold, silver, and aluminum.

  17. 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

  18. Diode Pumped Fiber Laser

    DTIC Science & Technology

    1983-07-01

    d AFWU.-TR-83-niO 00 H CO CO iH <^ DIODE PUMPED FIBER LASER Edward L. Glnzton Laboratory Stanford University Stanford, California 94305...RECIPIf NT’S CATALOG NUMBER 4. TITLE Cand Sub(i(/e; DIODE PUMPED FIBER LASER 5 TYPE OF REPORT & PERIOD COVERED Interim Report...external optical cavity made of two miniature flat mirrors, and end- pumped either at 514.5 nm (argon-ion laser ) or near 818 nm ( laser diode ). Coherent

  19. Atmospheric Imaging Assembly Observations of Coronal Loops: Cross-field Temperature Distributions

    NASA Astrophysics Data System (ADS)

    Schmelz, J. T.; Jenkins, B. S.; Pathak, S.

    2013-06-01

    We construct revised response functions for the Atmospheric Imaging Assembly (AIA) using the new atomic data, ionization equilibria, and coronal abundances available in CHIANTI 7.1. We then use these response functions in multithermal analysis of coronal loops, which allows us to determine a specific cross-field temperature distribution without ad hoc assumptions. Our method uses data from the six coronal filters and the Monte Carlo solutions available from our differential emission measure (DEM) analysis. The resulting temperature distributions are not consistent with isothermal plasma. Therefore, the observed loops cannot be modeled as single flux tubes and must be composed of a collection of magnetic strands. This result is now supported by observations from the High-resolution Coronal Imager, which show fine-scale braiding of coronal strands that are reconnecting and releasing energy. Multithermal analysis is one of the major scientific goals of AIA, and these results represent an important step toward the successful achievement of that goal. As AIA DEM analysis becomes more straightforward, the solar community will be able to take full advantage of the state-of-the-art spatial, temporal, and temperature resolution of the instrument.

  20. A model for the separation of large DNA molecules by crossed field gel electrophoresis.

    PubMed

    Southern, E M; Anand, R; Brown, W R; Fletcher, D S

    1987-08-11

    The idea that large DNA molecules adopt a stretched conformation as they pass through gels suggests a simple mechanism for the separation of DNA by crossed field electrophoresis: at each change in field direction a DNA molecule takes off in the new direction of the field by a movement which is led by what was formerly its back end. The effect of this ratcheting motion is to subtract from the DNA molecule's forward movement, at each step, an amount which is proportional to its length. We find that this model explains most of the features of the separation, and we describe experiments, using a novel electrophoresis apparatus, which support the model. The apparatus turns the gel between two preset orientations in a uniform electric field at preset time intervals. This separation method has the practical advantage over some others that the DNA molecules follow straight tracks. A further advantage is that the parameters which determine the separation are readily predicted from the simple theory describing their motion.

  1. An advection-diffusion model for cross-field runaway electron transport in perturbed magnetic fields

    NASA Astrophysics Data System (ADS)

    Särkimäki, Konsta; Hirvijoki, Eero; Decker, Joan; Varje, Jari; Kurki-Suonio, Taina

    2016-12-01

    Disruption-generated runaway electrons (RE) present an outstanding issue for ITER. The predictive computational studies of RE generation rely on orbit-averaged computations and, as such, they lack the effects from the magnetic field stochasticity. Since stochasticity is naturally present in post-disruption plasma, and externally induced stochastization offers a prominent mechanism to mitigate RE avalanche, we present an advection-diffusion model that can be used to couple an orbit-following code to an orbit-averaged tool in order to capture the cross-field transport and to overcome the latter’s limitation. The transport coefficients are evaluated via a Monte Carlo method. We show that the diffusion coefficient differs significantly from the well-known Rechester-Rosenbluth result. We also demonstrate the importance of including the advection: it has a two-fold role both in modelling transport barriers created by magnetic islands and in amplifying losses in regions where the islands are not present.

  2. ATMOSPHERIC IMAGING ASSEMBLY OBSERVATIONS OF CORONAL LOOPS: CROSS-FIELD TEMPERATURE DISTRIBUTIONS

    SciTech Connect

    Schmelz, J. T.; Jenkins, B. S.; Pathak, S.

    2013-06-10

    We construct revised response functions for the Atmospheric Imaging Assembly (AIA) using the new atomic data, ionization equilibria, and coronal abundances available in CHIANTI 7.1. We then use these response functions in multithermal analysis of coronal loops, which allows us to determine a specific cross-field temperature distribution without ad hoc assumptions. Our method uses data from the six coronal filters and the Monte Carlo solutions available from our differential emission measure (DEM) analysis. The resulting temperature distributions are not consistent with isothermal plasma. Therefore, the observed loops cannot be modeled as single flux tubes and must be composed of a collection of magnetic strands. This result is now supported by observations from the High-resolution Coronal Imager, which show fine-scale braiding of coronal strands that are reconnecting and releasing energy. Multithermal analysis is one of the major scientific goals of AIA, and these results represent an important step toward the successful achievement of that goal. As AIA DEM analysis becomes more straightforward, the solar community will be able to take full advantage of the state-of-the-art spatial, temporal, and temperature resolution of the instrument.

  3. Effect of Secondary Electron Emission on Electron Cross-Field Current in E×B Discharges

    SciTech Connect

    Yevgeny Raitses, Igor D. Kaganovich, Alexander Khrabrov, Dmytro Sydorenko, Nathaniel J. Fisch and Andrei Smolyakov

    2011-02-10

    This paper reviews and discusses recent experimental, theoretical, and numerical studies of plasma-wall interaction in a weakly collisional magnetized plasma bounded with channel walls made from different materials. A lowpressure ExB plasma discharge of the Hall thruster was used to characterize the electron current across the magnetic field and its dependence on the applied voltage and electron-induced secondary electron emission (SEE) from the channel wall. The presence of a depleted, anisotropic electron energy distribution function with beams of secondary electrons was predicted to explain the enhancement of the electron cross-field current observed in experiments. Without the SEE, the electron crossfield transport can be reduced from anomalously high to nearly classical collisional level. The suppression of SEE was achieved using an engineered carbon velvet material for the channel walls. Both theoretically and experimentally, it is shown that the electron emission from the walls can limit the maximum achievable electric field in the magnetized plasma. With nonemitting walls, the maximum electric field in the thruster can approach a fundamental limit for a quasineutral plasma.

  4. Cross-field electron transport induced by a rotating spoke in a cylindrical Hall thruster

    NASA Astrophysics Data System (ADS)

    Ellison, C. L.; Raitses, Y.; Fisch, N. J.

    2012-01-01

    Rotating spoke phenomena have been observed in a variety of Hall thruster and other E × B devices. It has been suggested that the spoke may be associated with the enhancement of the electron cross-field transport. In this paper, the current conducted across the magnetic field via a rotating spoke has been directly measured for the first time in the E × B discharge of a cylindrical Hall thruster. The spoke current was measured using a segmented anode. Synchronized measurements with a high speed camera and a four-segment anode allow observation of the current as a function of time and azimuthal position. Upwards of 50% of the total current is conducted through the spoke, which occupies a quarter of the Hall thruster channel area. To determine the transport mechanism, emissive and Langmuir probes were installed to measure fluctuating plasma potential, electron density, and temperature. A perturbed, azimuthal electric field and density are observed to oscillate in-phase with the rotating spoke. The resulting drift current is found to enhance electron transport with a magnitude equal to the spoke current to within margins of error.

  5. New perspectives on the dynamics of AC and DC plasma arcs exposed to cross-fields

    NASA Astrophysics Data System (ADS)

    Abdo, Youssef; Rohani, Vandad; Cauneau, François; Fulcheri, Laurent

    2017-02-01

    Interactions between an arc and external fields are crucially important for the design and the optimization of modern plasma torches. Multiple studies have been conducted to help better understand the behavior of DC and AC current arcs exposed to external and ‘self-induced’ magnetic fields, but the theoretical foundations remain very poorly explored. An analytical investigation has therefore been carried out in order to study the general behavior of DC and AC arcs under the effect of random cross-fields. A simple differential equation describing the general behavior of a planar DC or AC arc has been obtained. Several dimensionless numbers that depend primarily on arc and field parameters and the main arc characteristics (temperature, electric field strength) have also been determined. Their magnitude indicates the general tendency pattern of the arc evolution. The analytical results for many case studies have been validated using an MHD numerical model. The main purpose of this investigation was deriving a practical analytical model for the electric arc, rendering possible its stabilization and control, and the enhancement of the plasma torch power.

  6. Design and Simulation of the Recirculating Crossed-Field Planar Amplifier

    NASA Astrophysics Data System (ADS)

    Exelby, Steven; Greening, Geoffrey; Jordan, Nicholas; Simon, David; Lau, Yue Ying; Gilgenbach, Ronald; Hoff, Brad

    2016-10-01

    The Recirculating Planar Crossed-Field Amplifier (RPCFA) is a high power microwave device adapted from the Recirculating Planar Magnetron1, developed at the University of Michigan. A travelling-wave, rectangular, meander-line design has been developed in simulation that amplifies a 1.3 MW signal at 3 GHz to approximately 29 MW (13.5 dB) with nearly 53% electronic efficiency. Simulation also shows that the RPCFA is zero-drive stable, e.g., output of any appreciable power is dependent on the presence of an input RF signal. The amplifier was designed to be driven by the Michigan Electron Long Beam Accelerator (MELBA), which is currently configured to deliver a -300 kV, 1-10 kA, 0.3-1.0 µs pulse. Taking these parameters into consideration, a slow wave structure, cathode, and housing were designed using the finite element frequency domain code Ansys HFSS. The cold tube characteristics and RF field structures were then verified using the particle in cell code, MAGIC. Hot tube simulations on MAGIC were also run to calculate the RPCFA's performance, including gain and efficiency. Future work will include building a prototype RPCFA, cold testing, and performing experiments to verify the hot tube simulations. This work was supported by the AFOSR Grant FA9550-15-1-0097.

  7. A high power cross-field amplifier at X-Band

    SciTech Connect

    Eppley, K.; Feinstein, J.; Ko, K.; Kroll, N.; Lee, T.; Nelson, E.

    1991-05-01

    A high power cross-field amplifier is under development at SLAC with the objective of providing sufficient peak power to feed a section of an X-Band (11.424 GHz) accelerator without the need for pulse compression. The CFA being designed employs a conventional distributed secondary emission cathode but a novel anode structure which consists of an array of vane resonators alternatively coupled to a rectangular waveguide. The waveguide impedance (width) is tapered linearly from input to output so as to provide a constant RF voltage at the vane tips, leading to uniform power generation along the structure. Nominal design for this tube calls for 300 MW output power, 20 dB gain, DC voltage 142 KV, magnetic field 5 KG, anode-cathode gap 3.6 mm and total interaction length of about 60 cm. These specifications have been supported by computer simulations of both the RF slow wave structure as well as the electron space charge wave interaction. We have used ARGUS to model the cold circuit properties and CONDOR to model the electronic power conversion. An efficiency of 60 percent can be expected. We will discuss the details of the design effort. 5 refs., 6 figs.

  8. Role of cross-field drifts in the onset of divertor detachment

    NASA Astrophysics Data System (ADS)

    Groth, Mathias; Allen, S. L.; Fenstermacher, M. E.; Hill, D. H.; Makowski, M. A.; McLean, A. G.; Lasnier, C. J.; Porter, G. D.; Rognlien, T. D.; Briesemeister, A. R.; Unterberg, E. A.; Leonard, A. W.; Watkins, J. G.

    2015-11-01

    The impact of cross-field drifts in divertor configurations was investigated in DIII-D L and H-mode discharges. The studies show that the electron temperature at the outer divertor plate is reduced to below 2 eV at about 20 % lower pedestal density in configurations with the ion Bx ∇B direction toward the divertor X-point. When attached, these plasmas have significantly lower electron temperatures and and higher densities in the inner than in the outer divertor as directly measured with divertor Thomson scattering and inferred from line emission imaging using tangentially viewing cameras. Upon reversal of the toroidal field direction, the divertor conditions were observed in-out symmetric. Simulations with the edge fluid code UEDGE show that poloidal flows due to the radial electric field in the private flux region dominate the divertor asymmetries. Work supported by US DOE under DE-AC52-07NA27344, DE-FC02-04ER54698, DE-AC05-00OR22725, and DE-AC04-94AL85000.

  9. Cross-Field Current Instabilities in Thin Ionization Layers and the Enhanced Aurora

    SciTech Connect

    Jay R. Johnson and Hideo Okuda

    2008-05-20

    Nearly half of the time, auroral displays exhibit thin, bright layers known as \\enhanced aurora." There is a substantial body of evidence that connects these displays with thin, dense, heavy ion layers in the E-region. Based on the spectral characteristics of the enhanced layers, it is believed that they result when wave-particle interaction heats ambient electrons to energies at or just above the 17 eV ionization energy of N2. While there are several possible instabilities that could produce suprathermal electrons in thin layers, there has been no clear theoretical investigation which examines in detail how wave instabilities in the thin ionization layers could develop and produce the suprathermal electrons. We examine instabilities which would occur in thin, dense, heavy ion layers using extensive analytical analysis combined with particle simulations. We analyze a cross field current instability that is found to be strongly unstable in the heavy ion layers. Electrostatic simulations show that substantial heating of the ambient electrons occurs with energization at or above the N2 ionization energy.

  10. 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.

  11. Sputtering erosion in ion and plasma thrusters

    NASA Technical Reports Server (NTRS)

    Ray, Pradosh K.

    1995-01-01

    An experimental set-up to measure low-energy (below 1 keV) sputtering of materials is described. The materials to be bombarded represent ion thruster components as well as insulators used in the stationary plasma thruster. The sputtering takes place in a 9 inch diameter spherical vacuum chamber. Ions of argon, krypton and xenon are used to bombard the target materials. The sputtered neutral atoms are detected by a secondary neutral mass spectrometer (SNMS). Samples of copper, nickel, aluminum, silver and molybdenum are being sputtered initially to calibrate the spectrometer. The base pressure of the chamber is approximately 2 x 10(exp -9) Torr. the primary ion beam is generated by an ion gun which is capable of delivering ion currents in the range of 20 to 500 nA. The ion beam can be focused to a size approximately 1 mm in diameter. The mass spectrometer is positioned 10 mm from the target and at 90 deg angle to the primary ion beam direction. The ion beam impinges on the target at 45 deg. For sputtering of insulators, charge neutralization is performed by flooding the sample with electrons generated from an electron gun. Preliminary sputtering results, methods of calculating the instrument response function of the spectrometer and the relative sensitivity factors of the sputtered elements will be discussed.

  12. Sputtering erosion in ion and plasma thrusters

    NASA Technical Reports Server (NTRS)

    Ray, Pradosh K.

    1995-01-01

    An experimental set-up to measure low-energy (below 1 keV) sputtering of materials is described. The materials to be bombarded represent ion thruster components as well as insulators used in the stationary plasma thruster. The sputtering takes place in a 9 inch diameter spherical vacuum chamber. Ions of argon, krypton and xenon are used to bombard the target materials. The sputtered neutral atoms are detected by a secondary neutral mass spectrometer (SNMS). Samples of copper, nickel, aluminum, silver and molybdenum are being sputtered initially to calibrate the spectrometer. The base pressure of the chamber is approximately 2 x 10(exp -9) Torr. the primary ion beam is generated by an ion gun which is capable of delivering ion currents in the range of 20 to 500 nA. The ion beam can be focused to a size approximately 1 mm in diameter. The mass spectrometer is positioned 10 mm from the target and at 90 deg angle to the primary ion beam direction. The ion beam impinges on the target at 45 deg. For sputtering of insulators, charge neutralization is performed by flooding the sample with electrons generated from an electron gun. Preliminary sputtering results, methods of calculating the instrument response function of the spectrometer and the relative sensitivity factors of the sputtered elements will be discussed.

  13. 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.}

  14. A photon thermal diode.

    PubMed

    Chen, Zhen; Wong, Carlaton; Lubner, Sean; Yee, Shannon; Miller, John; Jang, Wanyoung; Hardin, Corey; Fong, Anthony; Garay, Javier E; Dames, Chris

    2014-11-17

    A thermal diode is a two-terminal nonlinear device that rectifies energy carriers (for example, photons, phonons and electrons) in the thermal domain, the heat transfer analogue to the familiar electrical diode. Effective thermal rectifiers could have an impact on diverse applications ranging from heat engines to refrigeration, thermal regulation of buildings and thermal logic. However, experimental demonstrations have lagged far behind theoretical proposals. Here we present the first experimental results for a photon thermal diode. The device is based on asymmetric scattering of ballistic energy carriers by pyramidal reflectors. Recent theoretical work has predicted that this ballistic mechanism also requires a nonlinearity in order to yield asymmetric thermal transport, a requirement of all thermal diodes arising from the second Law of Thermodynamics, and realized here using an 'inelastic thermal collimator' element. Experiments confirm both effects: with pyramids and collimator the thermal rectification is 10.9 ± 0.8%, while without the collimator no rectification is detectable (<0.3%).

  15. High-power sputtering employed for film deposition

    NASA Astrophysics Data System (ADS)

    Shapovalov, V. I.

    2017-07-01

    The features of high-power magnetron sputtering employed for the films’ deposition are reviewed. The main physical phenomena accompanying high-power sputtering including ion-electron emission, gas rarefaction, ionization of sputtered atoms, self-sputtering, ion sound waves and the impact of the target heating are described.

  16. Adherence of sputtered titanium carbides

    NASA Technical Reports Server (NTRS)

    Brainard, W. A.; Wheeler, D. R.

    1979-01-01

    The study searches for interface treatment that would increase the adhesion of TiC coating to nickel- and titanium-base alloys. Rene 41 (19 wt percent Cr, 11 wt percent Mo, 3 wt percent Ti, balance Ni) and Ti-6Al-4V (6 wt percent Al, 4 wt percent V, balance Ti) are considered. Adhesion of the coatings is evaluated in pin-and disk friction tests. The coatings and interface regions are examined by X-ray photoelectron spectroscopy. Results suggest that sputtered refractory compound coatings adhere best when a mixed compound of coating and substrate metals is formed in the interfacial region. The most effective type of refractory compound interface appears to depend on both substrate and coating material. A combination of metallic interlayer deposition and mixed compound interface formation may be more effective for some substrate coating combinations than either alone.

  17. Adherence of sputtered titanium carbides

    NASA Technical Reports Server (NTRS)

    Brainard, W. A.; Wheeler, D. R.

    1979-01-01

    The study searches for interface treatment that would increase the adhesion of TiC coating to nickel- and titanium-base alloys. Rene 41 (19 wt percent Cr, 11 wt percent Mo, 3 wt percent Ti, balance Ni) and Ti-6Al-4V (6 wt percent Al, 4 wt percent V, balance Ti) are considered. Adhesion of the coatings is evaluated in pin-and disk friction tests. The coatings and interface regions are examined by X-ray photoelectron spectroscopy. Results suggest that sputtered refractory compound coatings adhere best when a mixed compound of coating and substrate metals is formed in the interfacial region. The most effective type of refractory compound interface appears to depend on both substrate and coating material. A combination of metallic interlayer deposition and mixed compound interface formation may be more effective for some substrate coating combinations than either alone.

  18. Sputtering measurements using a quartz crystal microbalance as a catcher

    NASA Astrophysics Data System (ADS)

    Berger, Bernhard M.; Szabo, Paul S.; Stadlmayr, Reinhard; Aumayr, Friedrich

    2017-09-01

    A quartz crystal microbalance (QCM) catcher setup for sputter yield measurements is described. In this setup a QCM is placed next to the sputter target and acts as a catcher for sputtered material. The sputter yield evaluation relies on assumptions about the angular distribution of sputtered particles and reflected primary projectiles taken from simulations as well as on the knowledge of the sticking coefficient. To test this new setup a second QCM with a Au layer was used as a sputter target. The measured ratio between target and catcher signal is well reproduced in the simulations demonstrating the feasibility of reconstructing the sputtering yield from the catcher signal.

  19. Light-emitting Diodes

    PubMed Central

    Opel, Daniel R.; Hagstrom, Erika; Pace, Aaron K.; Sisto, Krisanne; Hirano-Ali, Stefanie A.; Desai, Shraddha

    2015-01-01

    Background: In the early 1990s, the biological significance of light-emitting diodes was realized. Since this discovery, various light sources have been investigated for their cutaneous effects. Study design: A Medline search was performed on light-emitting diode lights and their therapeutic effects between 1996 and 2010. Additionally, an open-label, investigator-blinded study was performed using a yellow light-emitting diode device to treat acne, rosacea, photoaging, alopecia areata, and androgenetic alopecia. Results: The authors identified several case-based reports, small case series, and a few randomized controlled trials evaluating the use of four different wavelengths of light-emitting diodes. These devices were classified as red, blue, yellow, or infrared, and covered a wide range of clinical applications. The 21 patients the authors treated had mixed results regarding patient satisfaction and pre- and post-treatment evaluation of improvement in clinical appearance. Conclusion: Review of the literature revealed that differing wavelengths of light-emitting diode devices have many beneficial effects, including wound healing, acne treatment, sunburn prevention, phototherapy for facial rhytides, and skin rejuvenation. The authors’ clinical experience with a specific yellow light-emitting diode device was mixed, depending on the condition being treated, and was likely influenced by the device parameters. PMID:26155326

  20. Nanoscale growth twins in sputtered metal films

    SciTech Connect

    Misra, Amit; Anderoglu, Osman; Hoagland, Richard G; Zhang, X

    2008-01-01

    We review recent studies on the mechanical properties of sputtered Cu and 330 stainless steel films with {l_brace}1 1 1{r_brace} nanoscale growth twins preferentially oriented perpendicular to growth direction. The mechanisms of formation of growth twins during sputtering and the deformation mechanisms that enable usually high strengths in nanotwinned structures are highlighted. Growth twins in sputtered films possess good thermal stability at elevated temperature, providing an approach to extend the application of high strength nanostructured metals to higher temperatures.

  1. Detection of sputtered metastable atoms by autoionization

    SciTech Connect

    Wucher, A.; Berthold, W.; Oechsner, H.; Franzreb, K.

    1994-03-01

    We report on a scheme for the detection of sputter-generated metastable atoms that is based on the resonant excitation of an autoionizing state by single-photon absorption from a tunable laser. Using this technique, sputtered silver atoms ejected in the metastable 4{ital d}{sup 9}5{ital s}{sup 2}{ital D}{sub 5/2} state with an excitation energy of 3.75 eV have been detected. This represents the highest excitation energy of sputtered metastable atoms observed so far.

  2. Modeling and analysis of surface roughness effects on sputtering, reflection, and sputtered particle transport

    SciTech Connect

    Brooks, J.N. ); Ruzic, D.N. )

    1990-01-01

    The microstructure of the redeposited surface in tokamaks may affect sputtering and reflection properties and subsequent particle transport. This subject has been studied numerically using coupled models/codes for near-surface plasma particle kinetic transport (WBC code) and rough surface sputtering (fractal-TRIM). The coupled codes provide an overall Monte Carlo calculation of the sputtering cascade resulting from an initial flux of hydrogen ions. Beryllium, carbon, and tungsten surfaces are analyzed for typical high recycling, oblique magnetic field, divertor conditions. Significant variations in computed sputtering rates are found with surface roughness. Beryllium exhibits high D-T and self-sputtering coefficients for the plasma regime studied (T{sub e} = 30-75 eV). Carbon and tungsten sputtering is significantly lower. 9 refs., 6 figs., 1 tab.

  3. Design of a high power cross field amplifier at X band with an internally coupled waveguide

    SciTech Connect

    Eppley, K.; Ko, Kwok.

    1991-01-01

    Cross field amplifiers (CFA) have been used in many applications where high power, high frequency microwaves are needed. Although these tubes have been manufactured for decades, theoretical analysis of their properties is not as highly developed as for other microwave devices such as klystrons. We have developed a simulation model for CFAs using the PIC code CONDOR. Our simulations indicate that there are limits to the maximum RF field strength that a CEA can sustain. When the fields become too high, efficiency becomes very poor, and the currents drawn may become so large that secondary emission cannot be maintained. It is therefore desirable to reduce the circuit impedance of a very high power tube. One method for doing this, proposed by Feinstein, involves periodically coupling a standard CFA circuit to an internal waveguide. Most of the power flows in the waveguide, so the overall impedance is much reduced. By adjusting the guide dimensions one can vary the impedance. Thus one can retain high impedance at the low power end but low impedance at the high power end. In principle one can maintain constant RF voltage throughout the tube. CONDOR simulations have identified a good operating point at X band, with power generation of over 5 MW per cm and total efficiency of over 60 percent. ARGUS simulations have modelled the cold test properties of the coupled structure. The nominal design specifications are 300 MW output, 17 db gain, frequency 11.4 GHz, dc voltage 142 kV, magnetic field 5 kG, anode cathode gap 3.6 mm, total interaction length about 60 cm. We will discuss the results of code simulations and report on the status of the experimental effort.

  4. Investigation of beryllium self-sputtering

    NASA Astrophysics Data System (ADS)

    Guseva, M. I.; Korshunov, S. N.; Gureev, V. M.; Martinenko, Yu. V.; Neumoin, V. E.; Stoljarova, V. G.

    1997-02-01

    The angular dependence of the beryllium self-sputtering yield ( Ys) has been investigated. The self-sputtering yield was measured as a function of the angle of ion incidence in the angle range of 0-85°. The measured data agree with those of the computer simulation at the angles of incidence: 0°, 30°, 45° and 85°. The maximum value of both the experimental and calculated beryllium self-sputtering yield occurs at the same angle of incidence -75°, but the experimental yield is reduced by a factor of 1.75 compared to the calculated value. The self-sputtering yield of beryllium is determined by the surface relief of microscopic scale created by ion bombardment.

  5. Interface states of Ag/(110)GaAs Schottky diodes without and with interfacial layers

    SciTech Connect

    Platen, W.; Schmutzler, H.; Kohl, D.; Brauchle, K.; Wolter, K.

    1988-07-01

    GaAs(110) faces with different preparations: ultrahigh vacuum (UHV) cleaved, polished and etched, polished and sputtered: are prepared as Schottky diodes by the deposition of Ag. Diodes based on UHV-cleaved faces do show homogeneously distributed EL2 and EL5 states in deep level transient spectroscopy (DLTS). On polished and etched samples an additional interface state (IS) distribution with a density of 9 x 10/sup 11/ eV/sup -1/ cm/sup -2/ at the DLTS maximum appears. These states can be caused by defects at the oxidic interfacial layer. Polishing and sputtering also evokes the IS distribution. The absence of a DLTS signal from metal-induced gap states (MIGS) which pin the Fermi level at 0.49 eV above the valence-band maximum is related to the absence of an interfacial layer in the UHV prepared Schottky diodes. The sputter process increases the electron density in a thin layer below the interface by an As excess. The corresponding smaller extent of the barrier causes an additional electron emission via tunneling processes from the IS distribution. Furthermore, a near-interface state, EL6 (V/sub Ga/-V/sub As/), shows up. Its concentration at the interface attains N/sub EL6/ = 2.5 x 10/sup 16/ cm/sup -3/ comparable to the shallow donor concentration.

  6. Sputtering of sodium on the planet Mercury

    NASA Technical Reports Server (NTRS)

    Mcgrath, M. A.; Johnson, R. E.; Lanzerotti, L. J.

    1986-01-01

    It is shown here that ion sputtering cannot account for the observed neutral sodium vapor column density on Mercury, but that it is an important loss mechanism for Na. Photons are likely to be the dominant stimulus, both directly through photodesorption and indirectly through thermal desorption of absorbed Na. It is concluded that the atmosphere produced is characterized by the planet's surface temperature, with the ion-sputtered Na contributing to a lesser, but more extended, component of the atmosphere.

  7. Heavy particle transport in sputtering systems

    NASA Astrophysics Data System (ADS)

    Trieschmann, Jan

    2015-09-01

    This contribution aims to discuss the theoretical background of heavy particle transport in plasma sputtering systems such as direct current magnetron sputtering (dcMS), high power impulse magnetron sputtering (HiPIMS), or multi frequency capacitively coupled plasmas (MFCCP). Due to inherently low process pressures below one Pa only kinetic simulation models are suitable. In this work a model appropriate for the description of the transport of film forming particles sputtered of a target material has been devised within the frame of the OpenFOAM software (specifically dsmcFoam). The three dimensional model comprises of ejection of sputtered particles into the reactor chamber, their collisional transport through the volume, as well as deposition of the latter onto the surrounding surfaces (i.e. substrates, walls). An angular dependent Thompson energy distribution fitted to results from Monte-Carlo simulations is assumed initially. Binary collisions are treated via the M1 collision model, a modified variable hard sphere (VHS) model. The dynamics of sputtered and background gas species can be resolved self-consistently following the direct simulation Monte-Carlo (DSMC) approach or, whenever possible, simplified based on the test particle method (TPM) with the assumption of a constant, non-stationary background at a given temperature. At the example of an MFCCP research reactor the transport of sputtered aluminum is specifically discussed. For the peculiar configuration and under typical process conditions with argon as process gas the transport of aluminum sputtered of a circular target is shown to be governed by a one dimensional interaction of the imposed and backscattered particle fluxes. The results are analyzed and discussed on the basis of the obtained velocity distribution functions (VDF). This work is supported by the German Research Foundation (DFG) in the frame of the Collaborative Research Centre TRR 87.

  8. Sputtering of sodium on the planet Mercury

    NASA Technical Reports Server (NTRS)

    Mcgrath, M. A.; Johnson, R. E.; Lanzerotti, L. J.

    1986-01-01

    It is shown here that ion sputtering cannot account for the observed neutral sodium vapor column density on Mercury, but that it is an important loss mechanism for Na. Photons are likely to be the dominant stimulus, both directly through photodesorption and indirectly through thermal desorption of absorbed Na. It is concluded that the atmosphere produced is characterized by the planet's surface temperature, with the ion-sputtered Na contributing to a lesser, but more extended, component of the atmosphere.

  9. Anisotropy of sapphire single crystal sputtering

    SciTech Connect

    Minnebaev, K. F.; Tolpin, K. A.; Yurasova, V. E.

    2015-08-15

    We have studied the spatial distribution of particles sputtered from the base (0001) plane of a sapphire single crystal with trigonal crystalline lattice (α-Al{sub 2}O{sub 3}) that can be considered a superposition of two hexagonal close packed (hcp) structures–the ideal sublattice of oxygen and a somewhat deformed sublattice of aluminum. It is established that the particles sputtered from the base plane of sapphire are predominantly deposited along the sides of an irregular hexagon with spots at its vertices. The patterns of spots have been also studied for sputtering of particles from the (0001) face of a zinc single crystal with the hcp lattice. The spots of sputtered Zn atoms are arranged at the vertices of concentric equilateral hexagons. In both cases, the observed anisotropy of sputtering is related to focused collisions (direct and assisted focusing) and the channeling process. The chemical composition of spots has been determined in various regions of sputtered sapphire deposition. The results are discussed in comparison to analogous earlier data for secondary ion emission from an α-Al{sub 2}O{sub 3} single crystal.

  10. 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.

  11. MD simulation of cluster formation during sputtering

    NASA Astrophysics Data System (ADS)

    Muramoto, T.; Okai, M.; Yamashita, Y.; Yorizane, K.; Yamamura, Y.

    2001-06-01

    The cluster ejection due to cluster impact on a solid surface is studied through molecular dynamics (MD) simulations. Simulations are performed for Cu cluster impacts on the Cu(1 1 1) surface for cluster energy 100 eV/atom, and for clusters of 6, 13, 28 and 55 atoms. Interatomic interactions are described by the AMLJ-EAM potential. The vibration energy spectrum is independent of the incident cluster size and energy. This comes from the fact that sputtered clusters become stable through the successive fragmentation of nascent large sputtered clusters. The vibration energy spectra for large sputtered clusters have a peak, whose energy corresponds to the melting temperature of Cu. The exponent of the power-law fit of the abundance distribution and the total sputtering yield for the cluster impacts are higher than that for the monatomic ion impacts with the same total energy, where the exponent δ is given by Yn∝ nδ and Yn is the yield of sputtered n-atom cluster. The exponent δ follows a unified function of the total sputtering yield, which is a monotonic increase function, and it is nearly equal to δ ˜ -3 for larger yield.

  12. The lunar exosphere: The sputtering contribution

    NASA Astrophysics Data System (ADS)

    Wurz, P.; Rohner, U.; Whitby, J. A.; Kolb, C.; Lammer, H.; Dobnikar, P.; Martín-Fernández, J. A.

    2007-11-01

    We have extended our Monte Carlo model of exospheres [Wurz, P., Lammer, H., 2003. Icarus 164 (1), 1-13] by treating the ion-induced sputtering process from a known surface in a self-consistent way. The comparison of the calculated exospheric densities with experimental data, which are mostly upper limits, shows that all of our calculated densities are within the measurement limits. The total calculated exospheric density at the lunar surface of about 1×10 m as result of solar wind sputtering we find is much less than the experimental total exospheric density of about 10 m. We conclude that sputtering contributes only a small fraction of the total exosphere, at least close to the surface. Because of the considerably larger scale height of atoms released via sputtering into the exosphere, sputtered atoms start to dominate the exosphere at altitudes exceeding a few 1000 km, with the exception of some light and abundant species released thermally, e.g. H 2, He, CH 4, and OH. Furthermore, for more refractory species such as calcium, our model indicates that sputtering may well be the dominant mechanism responsible for the lunar atmospheric inventory, but observational data does not yet allow firm conclusions to be drawn.

  13. Directed and diode percolation

    NASA Astrophysics Data System (ADS)

    Redner, S.

    1982-03-01

    We study the novel percolation phenomena that occur in random-lattice networks consisting of resistor-like and diode-like bonds. Resistor bonds connect or "transmit information" in either direction along their length, while diodes connect in one direction only. We first treat the special case of directed bond percolation, in which the diodes are aligned along a preferred axis. Mean-field theory shows that clusters become extremely anisotropic near the percolation transition and that their shapes are characterized by two correlation lengths, one parallel and one transverse to the preferred axis. These lengths diverge with exponents ν∥=1 and ν⊥=12, respectively, from which we can show that the upper critical dimension for this system must be five. We also treat a more general random network on the square lattice containing resistors and diodes of arbitrary orientation. Duality arguments are applied to obtain exact results for the location of phase transitions in this system. We then use a position-space renormalization-group approach to map out the phase diagram and calculate critical exponents. This system has an isotropic percolating phase, and phases which percolate in only one direction. Novel types of transitions occur between these phases, in which the diode orientation plays a fundamental role. These percolating phases meet with the nonpercolating phase along a line of multicritical points, where concentration and orientational fluctuations are simultaneously critical.

  14. Structural and electrical characterization of epitaxial Ge thin films on Si(001) formed by sputtering

    NASA Astrophysics Data System (ADS)

    Otsuka, Shintaro; Mori, Takahiro; Morita, Yukinori; Uchida, Noriyuki; Liu, Yongxun; O’uchi, Shin-ichi; Fuketa, Hiroshi; Migita, Shinji; Masahara, Meishoku; Matsukawa, Takashi

    2017-04-01

    We structurally and electrically characterize sub-10-nm-thick heteroepitaxial Ge films on Si(001), formed by heated sputtering and subsequent rapid thermal annealing (RTA). After RTA treatment at 720 °C, we find the heteroepitaxial Ge films to have smooth surfaces with a roughness root mean square value of 0.54 nm. Raman measurement reveals that the 720 °C RTA improves the crystallinity of Ge films while maintaining abrupt Ge/Si interfaces. Cross-sectional transmission electron microscopy confirms that the 720 °C RTA step effectively reduces stacking faults and dislocations in the Ge films. The Richardson plot of the TaN/Ge/n-Si diode indicates a Schottky barrier height (SBH) of 0.33 V, which is close to the height of 0.37 V measured from the capacitance–voltage measurement. These values are reasonable compared with the reported SBH of the TaN/bulk Ge Schottky barrier diode, indicating that the method involving heated sputtering and subsequent RTA provides adequate thin Ge films for Ge/Si heterostructures.

  15. Photovoltaic module bypass diode encapsulation

    NASA Technical Reports Server (NTRS)

    Shepard, N. J., Jr.

    1983-01-01

    The design and processing techniques necessary to incorporate bypass diodes within the module encapsulant are presented. The Semicon PN junction diode cells were selected. Diode junction to heat spreader thermal resistance measurements, performed on a variety of mounted diode chip types and sizes, have yielded values which are consistently below 1 deg C per watt, but show some instability when thermally cycled over the temperature range from -40 to 150 deg C. Three representative experimental modules, each incorporating integral bypass diode/heat spreader assemblies of various sizes, were designed. Thermal testing of these modules enabled the formulation of a recommended heat spreader plate sizing relationship. The production cost of three encapsulated bypass diode/heat spreader assemblies were compared with similarly rated externally mounted packaged diodes. It is concluded that, when proper designed and installed, these bypass diode devices will improve the overall reliability of a terrestrial array over a 20 year design lifetime.

  16. Analysis of surface sputtering on a quantum statistical basis

    NASA Technical Reports Server (NTRS)

    Wilhelm, H. E.

    1975-01-01

    Surface sputtering is explained theoretically by means of a 3-body sputtering mechanism involving the ion and two surface atoms of the solid. By means of quantum-statistical mechanics, a formula for the sputtering ratio S(E) is derived from first principles. The theoretical sputtering rate S(E) was found experimentally to be proportional to the square of the difference between incident ion energy and the threshold energy for sputtering of surface atoms at low ion energies. Extrapolation of the theoretical sputtering formula to larger ion energies indicates that S(E) reaches a saturation value and finally decreases at high ion energies. The theoretical sputtering ratios S(E) for wolfram, tantalum, and molybdenum are compared with the corresponding experimental sputtering curves in the low energy region from threshold sputtering energy to 120 eV above the respective threshold energy. Theory and experiment are shown to be in good agreement.

  17. Studies of internal sputtering in a 30-cm ion thruster

    NASA Technical Reports Server (NTRS)

    Mantenieks, M. A.; Rawlin, V. K.

    1975-01-01

    Initial studies have been made of the sputtering and deposition phenomena in a 30-cm thruster. Sputtering rates, of the cathode baffle, one of the main sources of sputtered material in a thruster, have beem measured by weight loss as a function of several thruster parameters. Sputtering rates were found to increase with both cathode flow rate and beam current when constant discharge voltage of 37 volts and power losses of 185 ev/ion were maintained. Sputtering rates were reduced 24% as discharge voltage was decreased from 37 to 33 volts while keeping discharge power constant. Qualitative agreement was found between sputtering rates obtained by the weight loss and those implied by spectroscopically observed line intensities of the excited iron sputtered atoms. After the completion of the sputtering tests, deposition and sputtering sites inside the thruster were identified.

  18. Studies of internal sputtering in a 30-cm ion thruster

    NASA Technical Reports Server (NTRS)

    Mantenieks, M. A.; Rawlin, V. K.

    1975-01-01

    Initial studies have been made of the sputtering and deposition phenomena in a 30-cm thruster. Sputtering rates, of the cathode baffle, one of the main sources of sputtered material in a thruster, have been measured by weight loss as a function of several thruster parameters. Sputtering rates were found to increase with both cathode flow rate and beam current when constant discharge voltage of 37 volts and power loses of 185 ev/ion were maintained. Sputtering rates were reduced 24% as discharge voltage was decreased from 37 to 33 volts while keeping discharge power constant. Qualitative agreement was found between sputtering rates obtained by the weight loss and those implied by spectroscopically observed line intensities of the excited iron sputtered atoms. After the completion of the sputtering tests, deposition and sputtering sites inside the thruster were identified.

  19. Low-energy sputterings with the Monte Carlo Program ACAT

    NASA Astrophysics Data System (ADS)

    Yamamura, Y.; Mizuno, Y.

    1985-05-01

    The Monte Carlo program ACAT was developed to determine the total sputtering yields and angular distributions of sputtered atoms in physical processes. From computer results of the incident-energy dependent sputterings for various ion-target combinations the mass-ratio dependence and the bombarding-angle dependence of sputtering thresholds was obtained with the help of the Matsunami empirical formula for sputtering yields. The mass-ratio dependence of sputtering thresholds is in good agreement with recent theoretical results. The threshold energy of light-ion sputtering is a slightly increasing function of angle of incidence, while that of heavy-ion sputtering has a minimum value near theta = 60 deg. The angular distributions of sputtered atoms are also calculated for heavy ions, medium ions, and light ions, and reasonable agreements between calculated angular distributions and experimental results are obtained.

  20. Nonlinear instability of the geomagnetotail current sheet combining the features of tearing and cross-field current instabilities

    NASA Astrophysics Data System (ADS)

    Kropotkin, A. P.; Trubachev, O. O.; Lui, A. T. Y.

    1999-01-01

    The substorm onset instability suggested in this paper combines the features of ``macroscale'' electromagnetic disturbance of the tearing mode type and the ``microscale'' plasma turbulence, which is generated by the cross-field current instability and modulated in coherence with the large-scale disturbance. Both components are involved in a feedback loop. It is assumed that the current sheet (CS) is thin enough for cross-field current instability (CCI) turbulence to already exist. Current density variations of the large-scale disturbance result in additional CCI generation; on the other hand, that additional plasma turbulence provides in quasi-linear approximation a flux of electrons which violates the frozen-in condition for magnetized electrons and thus destabilizes the tearing mode. The process is nonlinear. However, the threshold amplitude diminishes as the CS thins, so that the instability sets in when the threshold gets smaller than the background fluctuations.

  1. Diode Laser Arrays

    NASA Astrophysics Data System (ADS)

    Botez, Dan; Scifres, Don R.

    2005-11-01

    Contributors; 1. Monolithic phase-locked semiconductor laser arrays D. Botez; 2. High power coherent, semiconductor laser master oscillator power amplifiers and amplifier arrays D. F. Welch and D. G. Mehuys; 3. Microoptical components applied to incoherent and coherent laser arrays J. R. Leger; 4. Modeling of diode laser arrays G. R. Hadley; 5. Dynamics of coherent semiconductor laser arrays H. G. Winfuland and R. K. Defreez; 6. High average power semiconductor laser arrays and laser array packaging with an emphasis for pumping solid state lasers R. Solarz; 7. High power diode laser arrays and their reliability D. R. Scifres and H. H. Kung; 8. Strained layer quantum well heterostructure laser arrays J. J. Coleman; 9. Vertical cavity surface emitting laser arrays C. J. Chang-Hasnain; 10. Individually addressed arrays of diode lasers D. Carlin.

  2. 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.

  3. Steady State Chaotic Magnetic Fields and Particle Dynamics Cross-field Transport of Particles in Chaotic Magnetic Fields

    NASA Astrophysics Data System (ADS)

    Dasgupta, B.; Ram, A.

    2009-12-01

    The observed propagation of cosmic rays in the interplanetary space cannot be explained unless there is diffusion of the energetic particles across the interplanetary magnetic field. The cross-field diffusion of cosmic rays is assumed to be due to the chaotic nature of the interplanetary/intergalactic magnetic fields. Among the classic works on this subject have been those of Parker [1] and Jokipii [2]. Parker considered the passage of cosmic ray particles and energetic solar particles in a large scale magnetic field containing small scale irregularities. In the context of cosmic ray propagation, Jokipii considered a small fluctuating component, added on to a uniform magnetic field, to study the spatial transport of particles. We consider asymmetric, steady-state magnetic fields, in three spatial dimensions, generated by currents flowing in circular loops and straight lines [3]. We find that under very special circumstances can one generate large scale coherent magnetic fields. In general, even simple asymmetric current configurations generate spatially chaotic magnetic fields in three-dimensions. The motion of charged particles in these chaotic magnetic fields is quite coherent. This is a surprising result as one generally assumes that spatially chaotic magnetic fields will give rise to chaotic particle motion. So chaotic magnetic fields by themselves do not lead to cross-field transport. However, if we consider a current system, e.g., a current loop, embedded in a uniform magnetic field then a particle can undergo cross-field transport. For cross-field diffusion of charged particles it is necessary that the magnetic field lines be three dimensional. [1] E.N. Parker, Planet. Space Sci. 13, 9, (1965) [2] J.R. Jokipii, Astrophys. J. 146, 480, (1966). [3] A.K. Ram and B. Dasgupta, in 35th EPS Conference on Plasma Phys. Hersonissos, ECA Vol.32D, O-4.059 (2008); and Eos Trans. AGU 88 (52), Fall Meet. Suppl. Abstract NG21B-0522 (2007).

  4. Dual function conducting polymer diodes

    DOEpatents

    Heeger, Alan J.; Yu, Gang

    1996-01-01

    Dual function diodes based on conjugated organic polymer active layers are disclosed. When positively biased the diodes function as light emitters. When negatively biased they are highly efficient photodiodes. Methods of preparation and use of these diodes in displays and input/output devices are also disclosed.

  5. Structural and morphological properties of sputtered NiO thin films at various sputtering pressures

    SciTech Connect

    Reddy, A. Mallikarjuna; Reddy, Y. Ashok Kumar; Reddy, A. Sivasankar; Reddy, P. Sreedhara

    2012-06-05

    Nickel oxide thin films were successfully deposited on glass substrates at different sputtering pressures in the range of 3 x 10{sup -2} to 5 x 10{sup -2} mbar. It was observed that sputtering pressure influenced the structural and morphological properties. Structural properties were studied with X-ray diffractometer. All the deposited films were polycrystalline and exhibited cubic structure with preferential growth along (220) plane. From morphological studies it was observed that fine and uniform grains with RMS roughness of 9.4 nm were obtained when the films deposited at a sputtering pressure of 4 x 10{sup -2} mbar,. The grain size and the surface roughness decreased at higher sputtering pressures. The surface mobility of the adatoms decreased after series of collisions resulting in the decrease of grain size at high sputtering pressures.

  6. Sputtering - A vacuum deposition method for coating material.

    NASA Technical Reports Server (NTRS)

    Spalvins, T.

    1972-01-01

    The sputtering method is discussed in terms of the unique features which sputter offers in depositing coatings. These features include versatility, momentum transfer, configuration of target, precise controls, and a relatively slow deposition rate. Sputtered films are evaluated in terms of adherence, coherence, and the internal stresses. The observed strong adherence is attributed to the high kinetic energies of the sputtered material, sputter etched surface, and the submicroscopic particle size. Film thickness can be controlled to a millionth of a centimeter. Very adherent films of sputtered PTFE (teflon) can be deposited in a single operation on any type of material and on any geometrical configuration.

  7. Sputtering - A vacuum deposition method for coating material.

    NASA Technical Reports Server (NTRS)

    Spalvins, T.

    1972-01-01

    The sputtering method is discussed in terms of the unique features which sputter offers in depositing coatings. These features include versatility, momentum transfer, configuration of target, precise controls, and a relatively slow deposition rate. Sputtered films are evaluated in terms of adherence, coherence, and the internal stresses. The observed strong adherence is attributed to the high kinetic energies of the sputtered material, sputter etched surface, and the submicroscopic particle size. Film thickness can be controlled to a millionth of a centimeter. Very adherent films of sputtered PTFE (teflon) can be deposited in a single operation on any type of material and on any geometrical configuration.

  8. Molecular dynamics investigation of hexagonal boron nitride sputtering and sputtered particle characteristics

    NASA Astrophysics Data System (ADS)

    Smith, Brandon D.; Boyd, Iain D.

    2016-08-01

    The sputtering of hexagonal boron nitride (h-BN) by impacts of energetic xenon ions is investigated using a molecular dynamics (MD) model. The model is implemented within an open-source MD framework that utilizes graphics processing units to accelerate its calculations, allowing the sputtering process to be studied in much greater detail than has been feasible in the past. Integrated sputter yields are computed over a range of ion energies from 20 eV to 300 eV, and incidence angles from 0° to 75°. Sputtering of boron is shown to occur at energies as low as 40 eV at normal incidence, and sputtering of nitrogen at as low as 30 eV at normal incidence, suggesting a threshold energy between 20 eV and 40 eV. The sputter yields at 0° incidence are compared to existing experimental data and are shown to agree well over the range of ion energies investigated. The semi-empirical Bohdansky curve and an empirical exponential function are fit to the data at normal incidence, and the threshold energy for sputtering is calculated from the Bohdansky curve fit as 35 ± 2 eV. These results are shown to compare well with experimental observations that the threshold energy lies between 20 eV and 40 eV. It is demonstrated that h-BN sputters predominantly as atomic boron and diatomic nitrogen, and the velocity distribution function (VDF) of sputtered boron atoms is investigated. The calculated VDFs are found to reproduce the Sigmund-Thompson distribution predicted by Sigmund's linear cascade theory of sputtering. The average surface binding energy computed from Sigmund-Thompson curve fits is found to be 4.5 eV for ion energies of 100 eV and greater. This compares well to the value of 4.8 eV determined from independent experiments.

  9. Sputtering of Lunar Regolith by Solar Wind Protons and Heavy Ions, and General Aspects of Potential Sputtering

    NASA Technical Reports Server (NTRS)

    Alnussirat, S. T.; Sabra, M. S.; Barghouty, A. F.; Rickman, Douglas L.; Meyer, F.

    2014-01-01

    New simulation results for the sputtering of lunar soil surface by solar-wind protons and heavy ions will be presented. Previous simulation results showed that the sputtering process has significant effects and plays an important role in changing the surface chemical composition, setting the erosion rate and the sputtering process timescale. In this new work and in light of recent data, we briefly present some theoretical models which have been developed to describe the sputtering process and compare their results with recent calculation to investigate and differentiate the roles and the contributions of potential (or electrodynamic) sputtering from the standard (or kinetic) sputtering.

  10. Silicon Carbide Schottky Barrier Diode

    NASA Technical Reports Server (NTRS)

    Zhao, Jian H.; Sheng, Kuang; Lebron-Velilla, Ramon C.

    2004-01-01

    This chapter reviews the status of SiC Schottky barrier diode development. The fundamental of Schottky barrier diodes is first provided, followed by the review of high-voltage SiC Schottky barrier diodes, junction-barrier Schottky diodes, and merged-pin-Schottky diodes. The development history is reviewed ad the key performance parameters are discussed. Applications of SiC SBDs in power electronic circuits as well as other areas such as gas sensors, microwave and UV detections are also presented, followed by discussion of remaining challenges.

  11. New sputtering concept for optical precision coatings

    NASA Astrophysics Data System (ADS)

    Rademacher, Daniel; Bräuer, Günter; Vergöhl, Michael; Fritz, Benjamin; Zickenrott, Tobias

    2011-09-01

    The deposition of optical precision coatings on glass by magnetron sputtering is still a challenging problem regarding particle density and long term stability of coating plants due to target material erosion. A novel approach to increase process stability and reduce drifts is the usage of cylindrical cathodes. These cathodes allow a particle free deposition process as they have virtually no redeposition zones that can lead to destruction of coatings by arcing caused by surface charges. In the present paper optical single layers as well as multilayer coatings were sputtered by means of reactive magnetron sputtering using a double cylindrical cathode setup. The particle density is determined and compared to particles produced with planar magnetrons. A new sputter coater concept will be presented wherein the magnetrons are attached to a rotating disc coater in a sputter-up configuration. The process was stabilized by means of oxygen partial pressure control. Preliminary optical properties as well as deposition rates of different oxide films will be presented.

  12. A photon thermal diode

    PubMed Central

    Chen, Zhen; Wong, Carlaton; Lubner, Sean; Yee, Shannon; Miller, John; Jang, Wanyoung; Hardin, Corey; Fong, Anthony; Garay, Javier E.; Dames, Chris

    2014-01-01

    A thermal diode is a two-terminal nonlinear device that rectifies energy carriers (for example, photons, phonons and electrons) in the thermal domain, the heat transfer analogue to the familiar electrical diode. Effective thermal rectifiers could have an impact on diverse applications ranging from heat engines to refrigeration, thermal regulation of buildings and thermal logic. However, experimental demonstrations have lagged far behind theoretical proposals. Here we present the first experimental results for a photon thermal diode. The device is based on asymmetric scattering of ballistic energy carriers by pyramidal reflectors. Recent theoretical work has predicted that this ballistic mechanism also requires a nonlinearity in order to yield asymmetric thermal transport, a requirement of all thermal diodes arising from the second Law of Thermodynamics, and realized here using an ‘inelastic thermal collimator’ element. Experiments confirm both effects: with pyramids and collimator the thermal rectification is 10.9±0.8%, while without the collimator no rectification is detectable (<0.3%). PMID:25399761

  13. Sputtering of amorphous silicon nitride irradiated with energetic C60 ions: Preferential sputtering and synergy effect between electronic and collisional sputtering

    NASA Astrophysics Data System (ADS)

    Kitayama, T.; Morita, Y.; Nakajima, K.; Narumi, K.; Saitoh, Y.; Matsuda, M.; Sataka, M.; Toulemonde, M.; Kimura, K.

    2015-12-01

    Amorphous silicon nitride films (thickness 30 nm) deposited on Si(0 0 1) were irradiated with 30-1080 keV C60 and 100 MeV Xe ions to fluences ranging from 2 × 1011 to 1 × 1014 ions/cm2. The composition depth profiles of the irradiated samples were measured using high-resolution Rutherford backscattering spectrometry. The sputtering yields were estimated from the derived composition profiles. Pronounced preferential sputtering of nitrogen was observed in the electronic energy loss regime. In addition, a large synergy effect between the electronic and collisional sputtering was also observed. The sputtering yields were calculated using the unified thermal spike model to understand the observed results. Although the calculated results reproduced the observed total sputtering yields with a lowered sublimation energy, the observed preferential sputtering of nitrogen could not be explained. The present results suggest an additional sputtering mechanism related to the electronic energy loss.

  14. Solar Wind Sputtering of Lunar Surface Materials: Role and Some Possible Implications of Potential Sputtering

    NASA Technical Reports Server (NTRS)

    Barghouty, A. F.; Adams, J. H., Jr.; Meyer, F.; Reinhold, c.

    2010-01-01

    Solar-wind induced sputtering of the lunar surface includes, in principle, both kinetic and potential sputtering. The role of the latter mechanism, however, in many focused studies has not been properly ascertained due partly to lack of data but can also be attributed to the assertion that the contribution of solar-wind heavy ions to the total sputtering is quite low due to their low number density compared to solar-wind protons. Limited laboratory measurements show marked enhancements in the sputter yields of slow-moving, highly-charged ions impacting oxides. Lunar surface sputtering yields are important as they affect, e.g., estimates of the compositional changes in the lunar surface, its erosion rate, as well as its contribution to the exosphere as well as estimates of hydrogen and water contents. Since the typical range of solar-wind ions at 1 keV/amu is comparable to the thickness of the amorphous rim found on lunar soil grains, i.e. few 10s nm, lunar simulant samples JSC-1A AGGL are specifically enhanced to have such rims in addition to the other known characteristics of the actual lunar soil particles. However, most, if not all laboratory studies of potential sputtering were carried out in single crystal targets, quite different from the rim s amorphous structure. The effect of this structural difference on the extent of potential sputtering has not, to our knowledge, been investigated to date.

  15. A Fast Method of Fully Characterizing Sputtering Angular Dependence (Preprint)

    DTIC Science & Technology

    2008-06-17

    A new method has been demonstrated in which a single experiment is used to fully define the sputtering angular dependence of a given material. The...profilometry; the full sputtering angular dependence curve is then extracted using a numerical approach.

  16. Physical sputtering of metallic systems by charged-particle impact

    SciTech Connect

    Lam, N.Q.

    1989-12-01

    The present paper provides a brief overview of our current understanding of physical sputtering by charged-particle impact, with the emphasis on sputtering of metals and alloys under bombardment with particles that produce knock-on collisions. Fundamental aspects of ion-solid interactions, and recent developments in the study of sputtering of elemental targets and preferential sputtering in multicomponent materials are reviewed. We concentrate only on a few specific topics of sputter emission, including the various properties of the sputtered flux and depth of origin, and on connections between sputtering and other radiation-induced and -enhanced phenomena that modify the near-surface composition of the target. The synergistic effects of these diverse processes in changing the composition of the integrated sputtered-atom flux is described in simple physical terms, using selected examples of recent important progress. 325 refs., 27 figs.

  17. Possible isotopic fractionation effects in sputtered minerals

    NASA Technical Reports Server (NTRS)

    Haff, P. K.; Watson, C. C.; Tombrello, T. A.

    1980-01-01

    A model which makes definite predictions for the fractionation of isotopes in sputtered material is discussed. The fractionation patterns are nonlinear, and the pattern for a particular set of isotopes depends on the chemical matrix within which those isotopes are contained. Calculations are presented for all nonmonoisotopic elements contained in the minerals perovskite, anorthite, ackermanite, enstatite, and troilite. All isotopes are fractionated at the level of approximately 4-6 deg/o per atomic mass unit. Oxygen is always positively fractionated (heavier isotopes sputtered preferentially), and heavier elements are generally negatively fractioned (light isotopes sputtered preferentially). The value of Delta (O-18:O-16) is always less by about 1.8 deg/o than a linear extrapolation based upon the calculated delta (O-17:O-16) value would suggest. The phenomenon of both negative and positive fractionation patterns from a single target mineral are used to make an experimental test of the proposed model.

  18. Coulomb explosion sputtering of selectively oxidized Si

    NASA Astrophysics Data System (ADS)

    Karmakar, P.; Bhattacharjee, S.; Naik, V.; Sinha, A. K.; Chakrabarti, A.

    2010-05-01

    We have studied the sputtering of a unique system comprising of coexisting silicon and silicon oxide surfaces due to the impact of multiply charged Arq + ions. Such surfaces are produced by oblique angle oxygen ion bombardment on Si(100), which results in one side oxidized ripple formation due to preferential oxygen implantation. It is observed by atomic force microscopy and conducting atomic force microscopy studies that the higher the potential energy of the Arq + ion, the higher the sputtering yield of the nonconducting (oxide) side of the ripple as compared to the semiconducting side while ensuring an identical irradiation and measurement condition. It also shows experimentally the potential of highly charged ions in the gentle cleaning or tailoring of nanostructures. The results are explained in terms of the Coulomb explosion model, where potential sputtering depends on the conductivity of the ion impact sites.

  19. 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.

  20. Intergalactic medium metal enrichment through dust sputtering

    NASA Astrophysics Data System (ADS)

    Bianchi, Simone; Ferrara, Andrea

    2005-04-01

    We study the motion of dust grains into the intergalactic medium (IGM) around redshift z= 3, to test the hypothesis that grains can efficiently pollute the gas with metals through sputtering. We use the results available in the literature for radiation-driven dust ejection from galaxies as initial conditions and follow the motion onwards. Via this mechanism, grains are ejected into the IGM with velocities >100 km s-1 as they move supersonically, grains can be efficiently eroded by non-thermal sputtering. However, Coulomb and collisional drag forces effectively reduce the charged grain velocity. Up-to-date sputtering yields for graphite and silicate (olivine) grains have been derived using the code TRANSPORT OF IONS IN MATTER (TRIM), for which we provide analytic fits. After training our method on a homogeneous density case, we analyse the grain motion and sputtering in the IGM density field as derived from a Λ cold dark matter (CDM) cosmological simulation at z= 3.27. We found that only large (a>~ 0.1μm) grains can travel up to considerable distances (few ×100 kpc physical) before being stopped. Resulting metallicities show a well-defined trend with overdensity δ. The maximum metallicities are reached for 10 < δ < 100[corresponding to systems, in quasi-stellar object (QSO) absorption spectra, with 14.5 < log N(HI) < 16]. However the distribution of sputtered metals is very inhomogeneous, with only a small fraction of the IGM volume polluted by dust sputtering (filling factors of 18 per cent for Si and 6 per cent for C). For the adopted size distribution, grains are never completely destroyed; nevertheless, the extinction and gas photoelectric heating effects resulting from this population of intergalactic grains are well below current detection limits.

  1. Ion beam sputter etching and deposition of fluoropolymers

    NASA Technical Reports Server (NTRS)

    Banks, B. A.; Sovey, J. S.; Miller, T. B.; Crandall, K. S.

    1978-01-01

    Fluoropolymer etching and deposition techniques including thermal evaporation, RF sputtering, plasma polymerization, and ion beam sputtering are reviewed. Etching and deposition mechanism and material characteristics are discussed. Ion beam sputter etch rates for polytetrafluoroethylene (PTFE) were determined as a function of ion energy, current density and ion beam power density. Peel strengths were measured for epoxy bonds to various ion beam sputtered fluoropolymers. Coefficients of static and dynamic friction were measured for fluoropolymers deposited from ion bombarded PTFE.

  2. Ion beam sputter etching and deposition of fluoropolymers

    NASA Technical Reports Server (NTRS)

    Banks, B. A.; Sovey, J. S.; Miller, T. B.; Crandall, K. S.

    1978-01-01

    Fluoropolymer etching and deposition techniques including thermal evaporation, RF sputtering, plasma polymerization, and ion beam sputtering are reviewed. Etching and deposition mechanisms and material characteristics are discussed. Ion beam sputter etch rates for polytetrafluoroethylene (PTFE) were determined as a function of ion energy, current density and ion beam power density. Peel strengths were measured for epoxy bonds to various ion beam sputtered fluoropolymers. Coefficients of static and dynamic friction were measured for fluoropolymers deposited from ion bombarded PTFE.

  3. Process for preparing schottky diode contacts with predetermined barrier heights

    DOEpatents

    Chang, Y. Austin; Jan, Chia-Hong; Chen, Chia-Ping

    1996-01-01

    A process is provided for producing a Schottky diode having a preselected barrier height .phi..sub.Bn. The substrate is preferably n-GaAs, the metallic contact is derived from a starting alloy of the Formula [.SIGMA.M.sub..delta. ](Al.sub.x Ga.sub.1-x) wherein: .SIGMA.M is a moiety which consists of at least one M, and when more than one M is present, each M is different, M is a Group VIII metal selected from the group consisting of nickel, cobalt, ruthenium, rhodium, indium and platinum, .delta. is a stoichiometric coefficient whose total value in any given .SIGMA.M moiety is 1, and x is a positive number between 0 and 1 (that is, x ranges from greater than 0 to less than 1). Also, the starting alloy is capable of forming with the substrate a two phase equilibrium reciprocal system of the binary alloy mixture [.SIGMA.M.sub..delta. ]Ga-[.SIGMA.M.sub..delta. ]Al-AlAs-GaAs. When members of an alloy subclass within this Formula are each preliminarily correlated with the barrier height .phi..sub.Bn of a contact producable therewith, then Schottky diodes of predetermined barrier heights are producable by sputtering and annealing. Further provided are the product Schottky diodes that are produced according to this process.

  4. Carbonaceous Particles Production in a Sputtering Discharge

    SciTech Connect

    Dominique, Claire; Sant, Marco; Arnas, Cecile

    2005-10-31

    Spherical dust particles have been produced in argon glow discharge by sputtering of a graphite cathode. Their size varies from 40 to 200 nm depending on the distance between the two electrodes and the largest ones have a cauliflower shape. Simulations giving the evolution of the energy distribution of sputtered carbon atoms suggest a mechanism of growth by carbon vapour condensation. The chemical composition and structure of particles have been investigated by infrared spectroscopy and appear to be a complex arrangement of the carbon atoms and hetero-atoms.

  5. Sputtering Erosion in the Ion Thruster

    NASA Technical Reports Server (NTRS)

    Ray, Pradosh K.; Mantenieks, Maris A. (Technical Monitor)

    2000-01-01

    During the first phase of this research, the sputtering yields of molybdenum by low energy (100 eV and higher) xenon ions were measured by using the methods of secondary neutral mass spectrometry (SNMS) and Rutherford backscattering spectrometry (RBS). However, the measured sputtering yields were found to be far too low to explain the sputtering erosions observed in the long-duration tests of ion thrusters. The only difference between the sputtering yield measurement experiments and the ion thruster tests was that the later are conducted at high ion fluences. Hence, a study was initiated to investigate if any linkage exists between high ion fluence and an enhanced sputtering yield. The objective of this research is to gain an understanding of the causes of the discrepancies between the sputtering rates of molybdenum grids in an ion thruster and those measured from our experiments. We are developing a molecular dynamics simulation technique for studying low-energy xenon ion interactions with molybdenum. It is difficult to determine collision sequences analytically for primary ions below the 200 eV energy range where the ion energy is too low to be able to employ a random cascade model with confidence and it is too high to have to consider only single collision at or near the surface. At these low energies, the range of primary ions is about 1 to 2 nm from the surface and it takes less than 4 collisions on the average to get an ion to degrade to such an energy that it can no longer migrate. The fine details of atomic motion during the sputtering process are revealed through computer simulation schemes. By using an appropriate interatomic potential, the positions and velocities of the incident ion together with a sufficient number of target atoms are determined in small time steps. Hence, it allows one to study the evolution of damages in the target and its effect on the sputtering yield. We are at the preliminary stages of setting up the simulation program.

  6. Photonometers for coating and sputtering machines

    NASA Astrophysics Data System (ADS)

    Oupický, P.; Jareš, D.; Václavík, J.; Vápenka, D.

    2013-04-01

    The concept of photonometers (alternative name of optical monitor of a vacuum deposition process) for coating and sputtering machines is based on photonometers produced by companies like SATIS or HV Dresden. Photometers were developed in the TOPTEC centre and its predecessor VOD (Optical Development Workshop of Institut of Plasma Physics AS CR) for more than 10 years. The article describes current status of the technology and ideas which will be incorporated in next development steps. Hardware and software used on coating machines B63D, VNA600 and sputtering machine UPM810 is presented.

  7. Titanium aluminum nitride sputtered by HIPIMS

    NASA Astrophysics Data System (ADS)

    Weichart, Juergen; Lechthaler, Markus

    2012-09-01

    TiAlN was sputtered reactively by HIPIMS in the target compositions Ti/Al 33/67 and 50/50 using a modified OC Oerlikon Balzers INNOVA coating equipment. The resulting film properties like deposition rate, surface roughness, hardness, Young's modulus, wear, and film stress were analyzed as function of the nitrogen gas flow, pressure, target-substrate distance, and substrate bias. Furthermore, the films were characterized by X-ray diffraction and secondary electron microscopy of the cross section and the surface appearance. The process characteristics and film properties were compared with pulsed DC sputtering under the same conditions.

  8. Sputtering Erosion in the Ion Thruster

    NASA Technical Reports Server (NTRS)

    Ray, Pradosh K.; Mantenieks, Maris A. (Technical Monitor)

    2000-01-01

    During the first phase of this research, the sputtering yields of molybdenum by low energy (100 eV and higher) xenon ions were measured by using the methods of secondary neutral mass spectrometry (SNMS) and Rutherford backscattering spectrometry (RBS). However, the measured sputtering yields were found to be far too low to explain the sputtering erosions observed in the long-duration tests of ion thrusters. The only difference between the sputtering yield measurement experiments and the ion thruster tests was that the later are conducted at high ion fluences. Hence, a study was initiated to investigate if any linkage exists between high ion fluence and an enhanced sputtering yield. The objective of this research is to gain an understanding of the causes of the discrepancies between the sputtering rates of molybdenum grids in an ion thruster and those measured from our experiments. We are developing a molecular dynamics simulation technique for studying low-energy xenon ion interactions with molybdenum. It is difficult to determine collision sequences analytically for primary ions below the 200 eV energy range where the ion energy is too low to be able to employ a random cascade model with confidence and it is too high to have to consider only single collision at or near the surface. At these low energies, the range of primary ions is about 1 to 2 nm from the surface and it takes less than 4 collisions on the average to get an ion to degrade to such an energy that it can no longer migrate. The fine details of atomic motion during the sputtering process are revealed through computer simulation schemes. By using an appropriate interatomic potential, the positions and velocities of the incident ion together with a sufficient number of target atoms are determined in small time steps. Hence, it allows one to study the evolution of damages in the target and its effect on the sputtering yield. We are at the preliminary stages of setting up the simulation program.

  9. Method of sputter etching a surface

    DOEpatents

    Henager, C.H. Jr.

    1984-02-14

    The surface of a target is textured by co-sputter etching the target surface with a seed material adjacent thereto, while the target surface is maintained at a pre-selected temperature. By pre-selecting the temperature of the surface while sputter etching, it is possible to predetermine the reflectance properties of the etched surface. The surface may be textured to absorb sunlight efficiently and have minimal emittance in the infrared region so as to be well-suited for use as a solar absorber for photothermal energy conversion. 4 figs.

  10. Method of sputter etching a surface

    DOEpatents

    Henager, Jr., Charles H.

    1984-01-01

    The surface of a target is textured by co-sputter etching the target surface with a seed material adjacent thereto, while the target surface is maintained at a pre-selected temperature. By pre-selecting the temperature of the surface while sputter etching, it is possible to predetermine the reflectance properties of the etched surface. The surface may be textured to absorb sunlight efficiently and have minimal emittance in the infrared region so as to be well-suited for use as a solar absorber for photothermal energy conversion.

  11. Method of making segmented pyrolytic graphite sputtering targets

    DOEpatents

    McKernan, M.A.; Alford, C.S.; Makowiecki, D.M.; Chen, C.W.

    1994-02-08

    Anisotropic pyrolytic graphite wafers are oriented and bonded together such that the graphite's high thermal conductivity planes are maximized along the back surface of the segmented pyrolytic graphite target to allow for optimum heat conduction away from the sputter target's sputtering surface and to allow for maximum energy transmission from the target's sputtering surface. 2 figures.

  12. 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.

  13. Method of making segmented pyrolytic graphite sputtering targets

    DOEpatents

    McKernan, Mark A.; Alford, Craig S.; Makowiecki, Daniel M.; Chen, Chih-Wen

    1994-01-01

    Anisotropic pyrolytic graphite wafers are oriented and bonded together such that the graphite's high thermal conductivity planes are maximized along the back surface of the segmented pyrolytic graphite target to allow for optimum heat conduction away from the sputter target's sputtering surface and to allow for maximum energy transmission from the target's sputtering surface.

  14. THE HYDROMAGNETIC INTERIOR OF A SOLAR QUIESCENT PROMINENCE. II. MAGNETIC DISCONTINUITIES AND CROSS-FIELD MASS TRANSPORT

    SciTech Connect

    Low, B. C.; Casini, R.; Liu, W.; Berger, T.

    2012-09-20

    This second paper of the series investigates the transverse response of a magnetic field to the independent relaxation of its flux tubes of fluid seeking hydrostatic and energy balance, under the frozen-in condition and suppression of cross-field thermal conduction. The temperature, density, and pressure naturally develop discontinuities across the magnetic flux surfaces separating the tubes, requiring the finite pressure jumps to be compensated by magnetic-pressure jumps in cross-field force balance. The tangentially discontinuous fields are due to discrete currents in these surfaces, {delta}-function singularities in the current density that are fully admissible under the rigorous frozen-in condition but must dissipate resistively if the electrical conductivity is high but finite. The magnetic field and fluid must thus endlessly evolve by this spontaneous formation and resistive dissipation of discrete currents taking place intermittently in spacetime, even in a low-{beta} environment. This is a multi-dimensional effect in which the field plays a central role suppressed in the one-dimensional (1D) slab model of the first paper. The study begins with an order-of-magnitude demonstration that of the weak resistive and cross-field thermal diffusivities in the corona, the latter is significantly weaker for small {beta}. This case for spontaneous discrete currents, as an important example of the general theory of Parker, is illustrated with an analysis of singularity formation in three families of two-dimensional generalizations of the 1D slab model. The physical picture emerging completes the hypothesis formulated in Paper I that this intermittent process is the origin of the dynamic interiors of a class of quiescent prominences revealed by recent Hinode/SOT and SDO/AIA high-resolution observations.

  15. Cross-Field Differences in Creative Problem-Solving Skills: A Comparison of Health, Biological, and Social Sciences.

    PubMed

    Mumford, Michael D; Antes, Alison L; Caughron, Jared J; Connelly, Shane; Beeler, Cheryl

    2010-02-01

    In the present study, 258 doctoral students working in the health, biological, and social sciences were asked to solve a series of field-relevant problems calling for creative thought. Proposed solutions to these problems were scored with respect to critical creative thinking skills such as problem definition, conceptual combination, and idea generation. Results indicated that health, biological, and social scientists differed with respect to their skill in executing various operations, or processes, involved in creative thought. Interestingly, no differences were observed as a function of the students' level of experience. The implications of these findings for understanding cross-field, and cross-experience level, differences in creative thought are discussed.

  16. Quantum Hall Spin Diode

    NASA Astrophysics Data System (ADS)

    Eisenstein, J. P.; Pfeiffer, L. N.; West, K. W.

    2017-05-01

    Double layer two-dimensional electron systems at high perpendicular magnetic field are used to realize magnetic tunnel junctions in which the electrons at the Fermi level in the two layers have either parallel or antiparallel spin magnetizations. In the antiparallel case the tunnel junction, at low temperatures, behaves as a nearly ideal spin diode. At elevated temperatures the diode character degrades as long-wavelength spin waves are thermally excited. These tunnel junctions provide a demonstration that the spin polarization of the electrons in the N =1 Landau level at filling factors ν =5 /2 and 7 /2 is essentially complete, and, with the aid of an in-plane magnetic field component, that Landau level mixing at these filling factors is weak in the samples studied.

  17. Characterization of ZnO:SnO{sub 2} (50:50) thin film deposited by RF magnetron sputtering technique

    SciTech Connect

    Cynthia, S. R.; Sanjeeviraja, C.; Ponmudi, S.; Sivakumar, R.

    2016-05-06

    Zinc oxide (ZnO) and tin oxide (SnO{sub 2}) thin films have attracted significant interest recently for use in optoelectronic application such as solar cells, flat panel displays, photonic devices, laser diodes and gas sensors because of their desirable electrical and optical properties and wide band gap. In the present study, thin films of ZnO:SnO{sub 2} (50:50) were deposited on pre-cleaned microscopic glass substrate by RF magnetron sputtering technique. The substrate temperature and RF power induced changes in structural, surface morphological, compositional and optical properties of the films have been studied.

  18. Effect of sputtering power on the growth of Ru films deposited by magnetron sputtering

    SciTech Connect

    Jhanwar, Prachi; Kumar, Arvind; Rangra, K. J.; Verma, Seema

    2016-04-13

    Ruthenium is deposited by DC magnetron sputtering at different powers and is characterized. The effect of sputtering power on the electrical and structural properties of the film is investigated experimentally. High resolution X-ray diffraction is used to characterize the microstructure of Ru films deposited on SiO{sub 2} surface. The peak (002) is more sharp and intense with full width at half maximum (FWHM) of 0.37° at 250W. The grain size increases with increase in sputtering power improving the crystallinity of the film. The film deposited at high sputtering power also showed lower resistivity (12.40 µΩ-cm) and higher mobility (4.82 cm{sup 2}/V.s) as compared to the film deposited at low power. The surface morphology of the film is studied by atomic force microscopy (AFM).

  19. Effect of sputtering power on the growth of Ru films deposited by magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Jhanwar, Prachi; Kumar, Arvind; Verma, Seema; Rangra, K. J.

    2016-04-01

    Ruthenium is deposited by DC magnetron sputtering at different powers and is characterized. The effect of sputtering power on the electrical and structural properties of the film is investigated experimentally. High resolution X-ray diffraction is used to characterize the microstructure of Ru films deposited on SiO2 surface. The peak (002) is more sharp and intense with full width at half maximum (FWHM) of 0.37° at 250W. The grain size increases with increase in sputtering power improving the crystallinity of the film. The film deposited at high sputtering power also showed lower resistivity (12.40 µΩ-cm) and higher mobility (4.82 cm2/V.s) as compared to the film deposited at low power. The surface morphology of the film is studied by atomic force microscopy (AFM).

  20. Diode Code Development

    DTIC Science & Technology

    1990-10-01

    Research Corporation ,-_to model vacuum diode regions of -he DNA superpower ten terawatt generators such as the DNA/Aurora 14 TW pulse- at the Harry...r 2 . Energy conservation is then expresed by the formula j . E = d(KE)/dt + v. F, (12) where the pressure force is F = -V.p, and p is the pressure...SCIENCES CORPORATION SCIENCE APPLICATIONS INTL CORP ATTN: DASIAC ATTN: W CHADSEY LOCKHEED MISSILES & SPACE CO, INC SCIENCE APPLICATIONS INTL CORP ATTN: L

  1. Perforated diode neutron sensors

    NASA Astrophysics Data System (ADS)

    McNeil, Walter J.

    A novel design of neutron sensor was investigated and developed. The perforated, or micro-structured, diode neutron sensor is a concept that has the potential to enhance neutron sensitivity of a common solid-state sensor configuration. The common thin-film coated diode neutron sensor is the only semiconductor-based neutron sensor that has proven feasible for commercial use. However, the thin-film coating restricts neutron counting efficiency and severely limits the usefulness of the sensor. This research has shown that the perforated design, when properly implemented, can increase the neutron counting efficiency by greater than a factor of 4. Methods developed in this work enable detectors to be fabricated to meet needs such as miniaturization, portability, ruggedness, and adaptability. The new detectors may be used for unique applications such as neutron imaging or the search for special nuclear materials. The research and developments described in the work include the successful fabrication of variant perforated diode neutron detector designs, general explanations of fundamental radiation detector design (with added focus on neutron detection and compactness), as well as descriptive theory and sensor design modeling useful in predicting performance of these unique solid-state radiation sensors. Several aspects in design, fabrication, and operational performance have been considered and tested including neutron counting efficiency, gamma-ray response, perforation shapes and depths, and silicon processing variations. Finally, the successfully proven technology was applied to a 1-dimensional neutron sensor array system.

  2. Infrared diode laser spectroscopy

    NASA Astrophysics Data System (ADS)

    Civiš, S.; Cihelka, J.; Matulková, I.

    2010-12-01

    Three types of lasers (double-heterostructure 66 K InAsSb/InAsSbP laser diode, room temperature, multi quantum wells with distributed feedback (MQW with DFB) (GaInAsSb/AlGaAsSb based) diode laser and vertical cavity surface emitting lasers (VCSELs) (GaSb based) have been characterized using Fourier transform emission spectroscopy and compared. The photoacoustic technique was employed to determine the detection limit of formaldehyde (less than 1 ppmV) for the strongest absorption line of the v3 + v5 band in the emission region of the GaInAsSb/AlGaAsSb diode laser. The detection limit (less than 10 ppbV) of formaldehyde was achieved in the 2820 cm-1 spectral range in case of InAsSb/InAsSbP laser (fundamental bands of v1, v5). Laser sensitive detection (laser absorption together with high resolution Fourier transform infrared technique including direct laser linewidth measurement, infrared photoacoustic detection of neutral molecules (methane, form-aldehyde) is discussed. Additionally, very sensitive laser absorption techniques of such velocity modulation are discussed for case of laser application in laboratory research of molecular ions. Such sensitive techniques (originally developed for lasers) contributed very much in identifying laboratory microwave spectra of a series of anions (C6H-, C4H-, C2H-, CN-) and their discovery in the interstellar space (C6H-, C4H-).

  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. Continuous Sputter Deposition Coating of Long Monofilaments

    DTIC Science & Technology

    2014-04-01

    terminal. A length of fishing line, microtubing, or polylactic acid (PLA) coated with copper could be left to cure within an epoxy, and upon removal...inductance, capacitance, resistance min minute MSD magnetron sputter deposition PLA polylactic acid RPM revolutions per minute R resistance (units

  5. Research on Sputtering of Ferroelectric Thin Films

    DTIC Science & Technology

    1990-02-01

    and d1,5 coefficients as a function of composition in the PbNb 2 06-BaNb2O6 system. Fig. 4 Schematic representation of the sputter coating process. Fig...and photochromic 2 activities, and promises excellent optoelectronic properties. There have been numerous concepts for its application in elec- tronic

  6. RF Sputtering of Gold Contacts On Niobium

    NASA Technical Reports Server (NTRS)

    Barr, D. W.

    1983-01-01

    Reliable gold contacts are deposited on niobium by combination of RF sputtering and photolithography. Process results in structures having gold only where desired for electrical contact. Contacts are stable under repeated cycling from room temperature to 4.2 K and show room-temperature contact resistance as much as 40 percent below indium contacts made by thermalcompression bonding.

  7. 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

  8. Contrasting characteristics of aqueous reactive species induced by cross-field and linear-field plasma jets

    NASA Astrophysics Data System (ADS)

    Xu, Han; Chen, Chen; Liu, Dingxin; Xu, Dehui; Liu, Zhijie; Wang, Xiaohua; Kong, Michael G.

    2017-06-01

    A comparative study on aqueous reactive species in deionized water treated by two types of plasma jets is presented. Classified by the direction of the electric field in the jet device, a linear-field jet and cross-field jet have been set up. Concentrations of several aqueous reactive species are measured quantitatively by chemical fluorescent assays and electron spin resonance spectrometer. Results show that these two-type plasma jets would generate approximately the same gaseous reactive species under the same discharge power, but the linear-field plasma jet is much more efficient at delivering those species to the remote deionized water. This leads to a much more aqueous short-lived species including OH and \\text{O}2- produced in water, which are mainly correlated to the solvation of gaseous short-lived species such as ions and electrons. Regarding the long-lived species of aqueous H2O2, the concentration grows faster when treated by the linear-field plasma jet in the initial stage, but after 10 min it is similar to that treated by the cross-field counterpart due to the vapor-liquid equilibrium. The aqueous peroxynitrite is also predicted to be produced as a result of the air inclusion in the feeding gas.

  9. Cross-field diffusion of energetic (100 keV to 2 MeV) protons in interplanetary space

    SciTech Connect

    Costa Jr, Edio da; Tsurutani, Bruce T.; Alves, Maria Virgínia; Echer, Ezequiel; Lakhina, Gurbax S. E-mail: costajr.e@gmail.com

    2013-12-01

    Magnetic field magnitude decreases (MDs) are observed in several regions of the interplanetary medium. In this paper, we characterize MDs observed by the Ulysses spacecraft instrumentation over the solar south pole by using magnetic field data to obtain the empirical size, magnetic field MD, and frequency of occurrence distribution functions. The interaction of energetic (100 keV to 2 MeV) protons with these MDs is investigated. Charged particle and MD interactions can be described by a geometrical model allowing the calculation of the guiding center shift after each interaction. Using the distribution functions for the MD characteristics, Monte Carlo simulations are used to obtain the cross-field diffusion coefficients as a function of particle kinetic energy. It is found that the protons under consideration cross-field diffuse at a rate of up to ≈11% of the Bohm rate. The same method used in this paper can be applied to other space regions where MDs are observed, once their local features are well known.

  10. A new cryogenic diode thermometer

    NASA Astrophysics Data System (ADS)

    Courts, S. S.; Swinehart, P. R.; Yeager, C. J.

    2002-05-01

    While the introduction of yet another cryogenic diode thermometer is not earth shattering, a new diode thermometer, the DT-600 series, recently introduced by Lake Shore Cryotronics, possesses three features that make it unique among commercial diode thermometers. First, these diodes have been probed at the chip level, allowing for the availability of a bare chip thermometer matching a standard curve-an important feature in situations where real estate is at a premium (IR detectors), or where in-situ calibration is difficult. Second, the thermometry industry has assumed that interchangeability should be best at low temperatures. Thus, good interchangeability at room temperatures implies a very good interchangeability at cryogenic temperature, resulting in a premium priced sensor. The DT-600 series diode thermometer is available in an interchangeability band comparable to platinum RTDs with the added advantage of interchangeability to 2 K. Third, and most important, the DT-600 series diode does not exhibit an instability in the I-V characteristic in the 8 K to 20 K temperature range that is observed in other commercial diode thermometer devices [1]. This paper presents performance characteristics for the DT-600 series diode thermometer along with a comparison of I-V curves for this device and other commercial diode thermometers exhibiting an I-V instability.

  11. Cryogenic thermal diode heat pipes

    NASA Technical Reports Server (NTRS)

    Alario, J.

    1979-01-01

    The development of spiral artery cryogenic thermal diode heat pipes was continued. Ethane was the working fluid and stainless steel the heat pipe material in all cases. The major tasks included: (1) building a liquid blockage (blocking orifice) thermal diode suitable for the HEPP space flight experiment; (2) building a liquid trap thermal diode engineering model; (3) retesting the original liquid blockage engineering model, and (4) investigating the startup dynamics of artery cryogenic thermal diodes. An experimental investigation was also conducted into the wetting characteristics of ethane/stainless steel systems using a specially constructed chamber that permitted in situ observations.

  12. Annealing of gold nanostructures sputtered on glass substrate

    NASA Astrophysics Data System (ADS)

    Švorčík, V.; Siegel, J.; Šutta, P.; Mistrík, J.; Janíček, P.; Worsch, P.; Kolská, Z.

    2011-03-01

    The effects of annealing at 300 °C on gold nanostructures sputtered onto glass substrate were studied using XRD, SAXSees, the Van der Pauw method and ellipsometry. As-sputtered and annealed samples exhibit a different dependence of the gold lattice parameter on the sputtering time. With increasing sputtering time the average thickness of the layer and the size of gold crystallites increased. Another rapid enlargement of the crystallites is observed after annealing. The volume resistivity decreases rapidly with the increasing sputtering time for both, as-deposited and annealed structures. With increasing sputtering time initially discontinuous gold coverage changes gradually in a continuous one. Electrically continuous gold coverage on the as-sputtered and annealed samples exhibits the same concentration of free charge carriers and Hall mobility. Optical constants of as-deposited and annealed gold films determined by ellipsometry support resistivity measurements and clearly manifest the presence of plasmons in discontinuous films.

  13. Molecular dynamics investigation of hexagonal boron nitride sputtering and sputtered particle characteristics

    SciTech Connect

    Smith, Brandon D. Boyd, Iain D.

    2016-08-07

    The sputtering of hexagonal boron nitride (h-BN) by impacts of energetic xenon ions is investigated using a molecular dynamics (MD) model. The model is implemented within an open-source MD framework that utilizes graphics processing units to accelerate its calculations, allowing the sputtering process to be studied in much greater detail than has been feasible in the past. Integrated sputter yields are computed over a range of ion energies from 20 eV to 300 eV, and incidence angles from 0° to 75°. Sputtering of boron is shown to occur at energies as low as 40 eV at normal incidence, and sputtering of nitrogen at as low as 30 eV at normal incidence, suggesting a threshold energy between 20 eV and 40 eV. The sputter yields at 0° incidence are compared to existing experimental data and are shown to agree well over the range of ion energies investigated. The semi-empirical Bohdansky curve and an empirical exponential function are fit to the data at normal incidence, and the threshold energy for sputtering is calculated from the Bohdansky curve fit as 35 ± 2 eV. These results are shown to compare well with experimental observations that the threshold energy lies between 20 eV and 40 eV. It is demonstrated that h-BN sputters predominantly as atomic boron and diatomic nitrogen, and the velocity distribution function (VDF) of sputtered boron atoms is investigated. The calculated VDFs are found to reproduce the Sigmund-Thompson distribution predicted by Sigmund's linear cascade theory of sputtering. The average surface binding energy computed from Sigmund-Thompson curve fits is found to be 4.5 eV for ion energies of 100 eV and greater. This compares well to the value of 4.8 eV determined from independent experiments.

  14. Inverse I-V Injection Characteristics of ZnO Nanoparticle-Based Diodes.

    PubMed

    Mundt, Paul; Vogel, Stefan; Bonrad, Klaus; von Seggern, Heinz

    2016-08-10

    Simple Al/ZnO(NP)/Au diodes produced by spin coating of ZnO nanoparticle dispersions (ZnO(NP)) on Al/Al2O3 and Au substrates and subsequent Au deposition have been investigated to understand electron injection properties of more complex devices, incorporating ZnO(NP) as injection layer. Inverse I-V characteristics have been observed compared to conventional Al/ZnO(SP)/Au diodes produced by reactive ion sputtering of ZnO. SEM micrographs reveal that the void-containing contact of ZnO(NP) with the bottom Al electrode and the rough morphology of the top Au electrode are likely to be responsible for the observed injection and ejection probabilities of electrons. A simple tunneling model, incorporating the voids, explains the strongly reduced injection currents from Al whereas the top electrode fabricated by vapor deposition of Au onto the nanoparticle topology adopts the inverse ZnO(NP) morphology leading to enlarged injection areas combined with Au-tip landscapes. These tips in contrast to the smooth sputtered ZnO(SP) lead to electric field enhancement and strongly increased injection of electrons in reverse direction. The injected charge piles up at the barrier generated by voids between ZnO(NP) and the bottom electrode forcing a change in the barrier shape and therefore allowing for higher ejection rates. Both effects in combination explain the inverse I-V characteristic of nanoparticle based diodes.

  15. Cylindrical electron beam diode

    DOEpatents

    Bolduc, Paul E.

    1976-01-01

    A diode discharge device may include a tubular anode concentrically encircled by and spaced from a tubular cathode electrode with ends intermediate the ends of said anode electrode, and a metal conductive housing having a tubular wall disposed around the cathode electrode with end walls connected to the anode electrode. High energy electron current coupling is through an opening in the housing tubular wall to a portion of the cathode electrode intermediate its ends. Suitable utilization means may be within the anode electrode at positions to be irradiated by electrons emitted from the cathode electrode and transmitted through the anode walls.

  16. Infrared hot carrier diode mixer.

    PubMed

    Aukerman, L W; Erler, J W

    1977-11-01

    Detection of a 54.3-GHz beatnote at 10.6 microm has been observed with a hot carrier diode mixer. The diode consists of a "cat whisker" antenna, which forms an ohmic point contact to n-InAs. The mechanism of this room-temperature detector is described as the "thermoelectric effect" of hot carriers.

  17. JANTX1N3893 diode

    NASA Technical Reports Server (NTRS)

    1980-01-01

    Diodes manufactured by Siemens and Motorola were tested. Testing of Motorola diodes was stopped in all 3 groups because 50% failure-rate limit was reached. Siemens lot endured more testing in groups 1 and 2 and completed testing on group 3. Failure analysis was performed for group 2 testing.

  18. Ion Implantation of Silver Nanoparticles on Electrodeposited Polycarbazole Via Plasma Sputter Type Negative Ion Sources

    NASA Astrophysics Data System (ADS)

    Marquez, M. C.; Mascarinas, V.; Ramos, H.

    2017-09-01

    The discovery of conducting polymer has brought tremendous advancement in developing various polymeric materials, Carbazole pendants of poly(ethyl methacrylate) was cross-linked via an electrochemical route. The obtained film of poly( carbazole ethyl methacrylate) electrodeposited on the surface of indium tin oxide (ITO) was modified by implanting silver nanoparticles on its surface. This was done using Plasma Sputter-type Negative Ion Sources (PSTNIS) The modified and unmodified films of polycarbazole were characterized to assess its properties. Implanting silver nanoparticles on the surface of the cross-linked polymer abruptly changed its surface roughness, absorbance in the visible region and its current-voltage characteristic. A more pronounced diode-like characteristic was observed with a turn-on voltage of ∼0.4V. Investigation and tailoring the properties of electropolymerized carbazole attached to poly (ethyl methacrylate) backbone with implanted silver nanoparticles could lead to important materials with impact in optoelectronic devices.

  19. Nonepitaxial sputter synthesis of aligned strontium hexaferrite, SrOṡ6(Fe2O3), films

    NASA Astrophysics Data System (ADS)

    Hegde, H.; Samarasekara, P.; Cadieu, F. J.

    1994-05-01

    Films of strontium hexaferrite were synthesized through rf diode sputter deposition, nonepitaxially onto polycrystalline Al2O3 substrates. So far such films for the analogous Ba phase have been synthesized mostly through epitaxial growth onto suitably chosen matching substrates. Crystallization of the strontium hexaferrite phase was achieved for deposition temperatures as low as 500 °C. For nonepitaxially synthesized 2-3-μm-thick polycrystalline films, a fairly high degree of variable and controlled c-axis orientation of the crystallites has been obtained. The x-ray-diffraction traces of films with a strong c-axis in-plane alignment showed predominantly (110)-type reflections. The film coercivities were increased by postdeposition annealing in O2. The remnant to saturation flux density ratio of such in-plane anisotropy films for in-plane measurements was 0.62, with an in-plane coercivity ≊2.3 kOe.

  20. Sputtered Ta-Si-N diffusion barriers in Cu metallizations for Si

    NASA Technical Reports Server (NTRS)

    Kolawa, E.; Pokela, P. J.; Reid, J. S.; Chen, J. S.; Nicolet, Marc A.; Ruiz, R. P.

    1991-01-01

    Electrical measurements on shallow Si n+-p junction diodes with a 30-nm TiSi2 contacting layer demonstrate that an 80-nm-thick amorphous Ta36Si14N50 film prepared by reactive RF sputtering of a Ta5Si3 target in an Ar/N2 plasma very effectively prevents the interaction between the Si substrate with the TiSi2 contacting layer and a 500-nm Cu overlayer. The Ta36Si14N50 diffusion barrier maintains the integrity of the I-V characteristics up to 900 C for 30-min annealing in vacuum. It is concluded that the amorphous Ta36Si14N50 alloy is not only a material with a very low reactivity for copper, titanium, and silicon, but must have a small diffusivity for copper as well.

  1. Cross-Field Differences in Creative Problem-Solving Skills: A Comparison of Health, Biological, and Social Sciences

    PubMed Central

    Mumford, Michael D.; Antes, Alison L.; Caughron, Jared J.; Connelly, Shane; Beeler, Cheryl

    2010-01-01

    In the present study, 258 doctoral students working in the health, biological, and social sciences were asked to solve a series of field-relevant problems calling for creative thought. Proposed solutions to these problems were scored with respect to critical creative thinking skills such as problem definition, conceptual combination, and idea generation. Results indicated that health, biological, and social scientists differed with respect to their skill in executing various operations, or processes, involved in creative thought. Interestingly, no differences were observed as a function of the students’ level of experience. The implications of these findings for understanding cross-field, and cross-experience level, differences in creative thought are discussed. PMID:20936085

  2. Influence of crossed fields in structures combining large grain, bulk (RE)BCO superconductors and soft ferromagnetic discs

    NASA Astrophysics Data System (ADS)

    Philippe, M. P.; Fagnard, J. F.; Wéra, L.; Morita, M.; Nariki, S.; Teshima, H.; Caps, H.; Vanderheyden, B.; Vanderbemden, P.

    2016-03-01

    Bulk (RE)BCO superconductors are able to trap record magnetic fields and can be used as powerful permanent magnets in various engineering applications such as rotating machines and magnetic bearings. When such superconducting (SC) “trapped field magnets” are combined to a ferromagnetic (FM) disc, the total magnetic moment is increased with respect to that of the superconductor alone. In the present work, we study experimentally the magnetic behaviour of such hybrid FM/SC structures when they are subjected to cycles of applied field that are orthogonal to their permanent magnetization, i.e. a “crossed-field” configuration. Experimental results show that the usual “crossed-field demagnetization” caused by the cycles of transverse field is strongly reduced in the presence of the ferromagnet.

  3. Gallium phosphide high temperature diodes

    NASA Technical Reports Server (NTRS)

    Chaffin, R. J.; Dawson, L. R.

    1981-01-01

    High temperature (300 C) diodes for geothermal and other energy applications were developed. A comparison of reverse leakage currents of Si, GaAs, and GaP was made. Diodes made from GaP should be usable to 500 C. A Liquid Phase Epitaxy (LPE) process for producing high quality, grown junction GaP diodes is described. This process uses low vapor pressure Mg as a dopant which allows multiple boat growth in the same LPE run. These LPE wafers were cut into die and metallized to make the diodes. These diodes produce leakage currents below ten to the -9th power A/sq cm at 400 C while exhibiting good high temperature rectification characteristics. High temperature life test data is presented which shows exceptional stability of the V-I characteristics.

  4. Critical currents in sputtered copper molybdenum sulphide

    NASA Technical Reports Server (NTRS)

    Alterovitz, S. A.; Woollam, J. A.; Kammerdiner, L.; Luo, H.-L.

    1977-01-01

    Critical currents in a sputtered Chevrel-phase copper molybdenum sulfide have been measured at 4.2 K as a function of applied magnetic field. Self-field critical-current values up to 10 to the 9th A/sq m were found, decreasing to 10 to the 8th A/sq m at 3 T. Graphs of pinning forces versus field were found to be independent of field direction, and the pinning mechanism is sample independent. Critical-current densities for sputtered lead molybdenum sulphide are estimated to be about 10 to the 8th A/sq m at 26 T based on a scaling law for pinning.

  5. Simulation studies on sputtering in rough surface

    NASA Astrophysics Data System (ADS)

    Kenmotsu, T.; Yamamura, Y.; Muramoto, T.; Hirotani, N.

    2005-01-01

    The influence of a surface roughness on sputtering is studied using a Monte Carlo simulation code ACAT. In order to estimate this influence in ACAT calculation, the ACAT code is modified. The two-dimensional fractal surface model is applied to the ACAT code and a surface binding energy of a target material is estimated by a many-body tight-binding potential. Simulation results calculated with the modified ACAT are compared with experimental data and the standard planar ACAT on sputtering yields of a Mo surface irradiated with 2 keV D+ ions. The modified ACAT code predicts well experimental data from rough surfaces compared with the standard planar ACAT code.

  6. Sputtering of silicon at glancing incidence

    NASA Astrophysics Data System (ADS)

    Lindsey, S.; Hobler, G.

    2013-05-01

    Recent experimental sputtering yield data for Si sputtered by 30 keV Ga FIB shows a discrepancy with binary collision (BC) simulations for angles greater than 85°. This study investigates the factors of BC simulations that could be responsible for the discrepancy at glancing angles, including surface roughness, Ga implantation, electronic stopping, and surface binding energy. It is concluded that the dominant factor at glancing angles is surface roughness. Two roughness models, sinusoidal and pink noise, are used to demonstrate that very small amplitude (∼2 Å) roughness is required to obtain quantitative agreement with experiments at very glancing angles. Furthermore, it is shown that large amplitude roughness should be unstable under glancing angle beams.

  7. Critical currents in sputtered copper molybdenum sulphide

    NASA Technical Reports Server (NTRS)

    Alterovitz, S. A.; Woollam, J. A.; Kammerdiner, L.; Luo, H.-L.

    1977-01-01

    Critical currents in a sputtered Chevrel-phase copper molybdenum sulfide have been measured at 4.2 K as a function of applied magnetic field. Self-field critical-current values up to 10 to the 9th A/sq m were found, decreasing to 10 to the 8th A/sq m at 3 T. Graphs of pinning forces versus field were found to be independent of field direction, and the pinning mechanism is sample independent. Critical-current densities for sputtered lead molybdenum sulphide are estimated to be about 10 to the 8th A/sq m at 26 T based on a scaling law for pinning.

  8. Spin-wave diode

    DOE PAGES

    Lan, Jin; Yu, Weichao; Wu, Ruqian; ...

    2015-12-28

    A diode, a device allowing unidirectional signal transmission, is a fundamental element of logic structures, and it lies at the heart of modern information systems. The spin wave or magnon, representing a collective quasiparticle excitation of the magnetic order in magnetic materials, is a promising candidate for an information carrier for the next-generation energy-saving technologies. Here, we propose a scalable and reprogrammable pure spin-wave logic hardware architecture using domain walls and surface anisotropy stripes as waveguides on a single magnetic wafer. We demonstrate theoretically the design principle of the simplest logic component, a spin-wave diode, utilizing the chiral bound statesmore » in a magnetic domain wall with a Dzyaloshinskii-Moriya interaction, and confirm its performance through micromagnetic simulations. As a result, these findings open a new vista for realizing different types of pure spin-wave logic components and finally achieving an energy-efficient and hardware-reprogrammable spin-wave computer.« less

  9. Light Emitting Diode (LED)

    NASA Technical Reports Server (NTRS)

    1997-01-01

    A special lighting technology was developed for space-based commercial plant growth research on NASA's Space Shuttle. Surgeons have used this technology to treat brain cancer on Earth, in two successful operations. The treatment technique called photodynamic therapy, requires the surgeon to use tiny pinhead-size Light Emitting Diodes (LEDs) (a source releasing long wavelengths of light) to activate light-sensitive, tumor-treating drugs. Laser light has been used for this type of surgery in the past, but the LED light illuminates through all nearby tissues, reaching parts of a tumor that shorter wavelengths of laser light carnot. The new probe is safer because the longer wavelengths of light are cooler than the shorter wavelengths of laser light, making the LED less likely to injure normal brain tissue near the tumor. It can also be used for hours at a time while still remaining cool to the touch. The LED probe consists of 144 tiny pinhead-size diodes, is 9-inches long, and about one-half-inch in diameter. The small balloon aids in even distribution of the light source. The LED light source is compact, about the size of a briefcase, and can be purchased for a fraction of the cost of a laser. The probe was developed for photodynamic cancer therapy by the Marshall Space Flight Center under a NASA Small Business Innovative Research program grant.

  10. Light Emitting Diode (LED)

    NASA Technical Reports Server (NTRS)

    1997-01-01

    A special lighting technology was developed for space-based commercial plant growth research on NASA's Space Shuttle. Surgeons have used this technology to treat brain cancer on Earth, in two successful operations. The treatment technique called photodynamic therapy, requires the surgeon to use tiny pinhead-size Light Emitting Diodes (LEDs) (a source releasing long wavelengths of light) to activate light-sensitive, tumor-treating drugs. Laser light has been used for this type of surgery in the past, but the LED light illuminates through all nearby tissues, reaching parts of a tumor that shorter wavelengths of laser light carnot. The new probe is safer because the longer wavelengths of light are cooler than the shorter wavelengths of laser light, making the LED less likely to injure normal brain tissue near the tumor. It can also be used for hours at a time while still remaining cool to the touch. The LED probe consists of 144 tiny pinhead-size diodes, is 9-inches long, and about one-half-inch in diameter. The small balloon aids in even distribution of the light source. The LED light source is compact, about the size of a briefcase, and can be purchased for a fraction of the cost of a laser. The probe was developed for photodynamic cancer therapy by the Marshall Space Flight Center under a NASA Small Business Innovative Research program grant.

  11. Textured carbon surfaces on copper by sputtering

    NASA Technical Reports Server (NTRS)

    Curren, A. N. (Inventor); Jensen, K. A. (Inventor); Roman, R. F. (Inventor)

    1986-01-01

    A very thin layer of highly textured carbon is applied to a copper surface by a triode sputtering process. A carbon target and a copper substrate are simultaneously exposed to an argon plasma in a vacuum chamber. The resulting carbon surface is characterized by a dense, random array of needle like spires or peaks which extend perpendicularly from the copper surface. The coated copper is especially useful for electrode plates in multistage depressed collectors.

  12. Sputtering Erosion in Ion and Plasma Thrusters

    NASA Technical Reports Server (NTRS)

    Ray, Pradosh K.

    1996-01-01

    Low energy sputtering of molybdenum, tantalum and boron nitride with xenon ions are being studied using secondary neutral and secondary ion mass spectrometry (SNMS/SIMS). An ultrahigh vacuum chamber was used to conduct the experiment at a base pressure of 1x10(exp -9) torr. The primary ion beam is generated by an ion gun which is capable of delivering ion currents in the range of 20 to 500 nA. The ion beam can be focused to a spot size of approximately 1 mm in diameter. The mass spectrometer is positioned 10 mm from the target and 90 deg to the primary ion beam direction. SNMS and SIMS spectra were collected at various incident angles and different ion energies. For boron nitride sputtering, the target was flooded with an electron beam to neutralize the charge buildup on the surface. In the SNMS mode, sputtering of Mo and Ta can be detected at an ion energy as low as 100 eV whereas in boron nitride the same was observed up to an energy of 300 eV. However, in the positive-SIMS mode, the sputtering of Mo was observed at 10 eV incident ion energy. The SIMS spectra obtained for boron nitride clearly identifies the two isotopes of boron as well as cluster ions such as B2(sup +) and molecular ions such as BN(sup +). From the angle versus yields measurements, it was found that the maximum SNMS yield shifts towards lower incident angles at low ion energies for all three samples.

  13. Sputter coating of microspherical substrates by levitation

    SciTech Connect

    Lowe, Arthur T.; Hosford, Charles D.

    1981-01-01

    Microspheres are substantially uniformly coated with metals or nonmetals by simultaneously levitating them and sputter coating them at total chamber pressures less than 1 torr. A collimated hole structure 12 comprising a parallel array of upwardly projecting individual gas outlets 16 is machined out to form a dimple 11. Glass microballoons, which are particularly useful in laser fusion applications, can be substantially uniformly coated using the coating method and apparatus.

  14. Sputter coating of microspherical substrates by levitation

    DOEpatents

    Lowe, A.T.; Hosford, C.D.

    Microspheres are substantially uniformly coated with metals or nonmetals by simltaneously levitating them and sputter coating them at total chamber pressures less than 1 torr. A collimated hole structure comprising a parallel array of upwardly projecting individual gas outlets is machined out to form a dimple. Glass microballoons,, which are particularly useful in laser fusion applications, can be substantially uniformly coated using the coating method and apparatus.

  15. Sputter coating of microspherical substrates by levitation

    SciTech Connect

    Hosford, C.D.; Lowe, A.T.

    1981-11-24

    Microspheres are substantially uniformly coated with metals or nonmetals by simultaneously levitating them and sputter coating them at total chamber pressures less than 1 torr. A collimated hole structure comprising a parallel array of upwardly projecting individual gas outlets is machined out to form a dimple. Glass microballoons, which are particularly useful in laser fusion applications, can be substantially uniformly coated using the coating method and apparatus.

  16. Sputtering Erosion in Ion and Plasma Thrusters

    NASA Technical Reports Server (NTRS)

    Ray, Pradosh K.

    1996-01-01

    Low energy sputtering of molybdenum, tantalum and boron nitride with xenon ions are being studied using secondary neutral and secondary ion mass spectrometry (SNMS/SIMS). An ultrahigh vacuum chamber was used to conduct the experiment at a base pressure of 1x10(exp -9) torr. The primary ion beam is generated by an ion gun which is capable of delivering ion currents in the range of 20 to 500 nA. The ion beam can be focused to a spot size of approximately 1 mm in diameter. The mass spectrometer is positioned 10 mm from the target and 90 deg to the primary ion beam direction. SNMS and SIMS spectra were collected at various incident angles and different ion energies. For boron nitride sputtering, the target was flooded with an electron beam to neutralize the charge buildup on the surface. In the SNMS mode, sputtering of Mo and Ta can be detected at an ion energy as low as 100 eV whereas in boron nitride the same was observed up to an energy of 300 eV. However, in the positive-SIMS mode, the sputtering of Mo was observed at 10 eV incident ion energy. The SIMS spectra obtained for boron nitride clearly identifies the two isotopes of boron as well as cluster ions such as B2(sup +) and molecular ions such as BN(sup +). From the angle versus yields measurements, it was found that the maximum SNMS yield shifts towards lower incident angles at low ion energies for all three samples.

  17. Development of sputtered techniques for thrust chambers

    NASA Technical Reports Server (NTRS)

    Mullaly, J. R.; Hecht, R. J.; Schmid, T. E.; Torrey, C. T.

    1975-01-01

    Techniques and materials were developed and evaluated for the fabrication and coating of advanced, long life, regeneratively cooled thrust chambers. Materials were analyzed as fillers for sputter application of OFHC copper as a closeout layer to channeled inner structures; of the materials evaluated, aluminum was found to provide the highest bond strength and to be the most desirable for chamber fabrication. The structures and properties were investigated of thick sputtered OFHC copper, 0.15 Zr-Cu, Al2O3,-Cu, and SiC-Cu. Layered structures of OFHC copper and 0.15 Zr-Cu were investigated as means of improving chamber inner wall fatigue life. The evaluation of sputtered Ti-5Al-2.5Sn, NASA IIb-11, aluminum and Al2O3-Al alloys as high strength chamber outer jackets was performed. Techniques for refurbishing degraded thrust chambers with OFHC copper and coating thrust chambers with protective ZrO2 and graded ZrO2-copper thermal barrier coatings were developed.

  18. Multilayer thin film thermoelectrics produced by sputtering

    SciTech Connect

    Wagner, A.V.; Foreman, R.J.; Summers, L.J.; Barbee, T.W. Jr.; Farmer, J.C.

    1995-06-19

    In this work we explore the possibility of achieving bulk electrical properties in single layer sputter deposited films grown epitaxially on (111) oriented BaF{sub 2} substrates. There are a number of sputter deposition parameters that can be varied in order to optimize the film quality. It is important to understand the effect of varying the deposition temperature, Ar sputtering gas pressure, and the substrate bias. We will consider only Bi and Bi{sub 0.86}Sb{sub 0.14} films in this paper. These materials were chosen since they have the same simple structure, two different band gaps and do not change significantly either in physical or electrical properties with small amounts of cross contamination. We will also present our work on multilayer thermoelectrics made of Bi and Bi{sub 0.86}Sb{sub 0.14} layers. There has been considerable interest in this multilayer structure in the literature. Theoretical calculations of the band structure and interface states of these multilayer structures have been made by Mustafaev and Agassi et al. respectively [6,7]. Experimentally Yoshida et al. have examined similar multilayer structures grown by MBE as well as Bi/Sb multilayer samples in which report an anomalous thermoelectric power [8].

  19. Structural and optical properties of sputtered ZnO thin films

    NASA Astrophysics Data System (ADS)

    Flickyngerova, S.; Shtereva, K.; Stenova, V.; Hasko, D.; Novotny, I.; Tvarozek, V.; Sutta, P.; Vavrinsky, E.

    2008-04-01

    Zinc oxide (ZnO) and aluminium-doped zinc oxide (ZnO:Al) thin films were prepared by RF diode sputtering at varying deposition conditions. The effects of negative bias voltage and RF power on structural and optical properties were investigated. X-ray diffraction measurements (XRD) confirmed that both un-doped and Al-doped ZnO films are polycrystalline and have hexagonal wurtzite structure. The preferential <0 0 1> orientation and surface roughness evaluated by AFM measurements showed dependence on applied bias voltage and RF power. The sputtered ZnO and ZnO:Al films had high optical transmittance (>90%) in the wavelength range of 400-800 nm, which was not influenced by bias voltage and RF power. ZnO:Al were conductive and highly transparent. Optical band gap of un-doped and Al-doped ZnO thin films depended on negative bias and RF power and in both cases showed tendency to narrowing.

  20. Sputtering from a Porous Material by Penetrating Ions

    NASA Technical Reports Server (NTRS)

    Rodriguez-Nieva, J. F.; Bringa, E. M.; Cassidy, T. A.; Johnson, R. E.; Caro, A.; Fama, M.; Loeffler, M.; Baragiola, R. A.; Farkas, D.

    2012-01-01

    Porous materials are ubiquitous in the universe and weathering of porous surfaces plays an important role in the evolution of planetary and interstellar materials. Sputtering of porous solids in particular can influence atmosphere formation, surface reflectivity, and the production of the ambient gas around materials in space, Several previous studies and models have shown a large reduction in the sputtering of a porous solid compared to the sputtering of the non-porous solid. Using molecular dynamics simulations we study the sputtering of a nanoporous solid with 55% of the solid density. We calculate the electronic sputtering induced by a fast, penetrating ion, using a thermal spike representation of the deposited energy. We find that sputtering for this porous solid is, surprisingly, the same as that for a full-density solid, even though the sticking coefficient is high.

  1. Sputtering from a Porous Material by Penetrating Ions

    NASA Technical Reports Server (NTRS)

    Rodriguez-Nieva, J. F.; Bringa, E. M.; Cassidy, T. A.; Johnson, R. E.; Caro, A.; Fama, M.; Loeffler, M.; Baragiola, R. A.; Farkas, D.

    2012-01-01

    Porous materials are ubiquitous in the universe and weathering of porous surfaces plays an important role in the evolution of planetary and interstellar materials. Sputtering of porous solids in particular can influence atmosphere formation, surface reflectivity, and the production of the ambient gas around materials in space, Several previous studies and models have shown a large reduction in the sputtering of a porous solid compared to the sputtering of the non-porous solid. Using molecular dynamics simulations we study the sputtering of a nanoporous solid with 55% of the solid density. We calculate the electronic sputtering induced by a fast, penetrating ion, using a thermal spike representation of the deposited energy. We find that sputtering for this porous solid is, surprisingly, the same as that for a full-density solid, even though the sticking coefficient is high.

  2. Sputtering: A vacuum deposition method for coating material

    NASA Technical Reports Server (NTRS)

    Spalvins, T.

    1972-01-01

    The sputtering process is described in terms of its features: versatility, momentum transfer, configuration of target, precise controls and the relatively slow deposition rate. Sputtered films are evaluated in terms of adherence, coherence, and internal stresses. The strong adherence is attributed to the high kinetic energies of the sputtered material, sputter etched (cleaned) surface, and the submicroscopic particle size. An illustration is a sputtered solid film lubricant such as MoS2. Friction tests were conducted on a thin, 2000 A deg thick MoS2 film. These films are very dense and without observable pinholes, and the particle to particle cohesion is strong. Tolerances (film thickness) can be controlled to a millionth of a centimeter. Very adherent films of sputtered Teflon can be deposited in a single operation on any type of material (metal, glass, paper) and on any geometrical configuration with a dense adherent film.

  3. Mass fractionation of the lunar surface by solar wind sputtering

    NASA Technical Reports Server (NTRS)

    Switkowski, Z. E.; Haff, P. K.; Tombrello, T. A.; Burnett, D. S.

    1975-01-01

    The sputtering of the lunar surface by the solar wind is examined as a possible mechanism of mass fractionation. Simple arguments based on current theories of sputtering and the ballistics of the sputtered atoms suggest that most ejected atoms will have sufficiently high energy to escape lunar gravity. However, the fraction of atoms which falls back to the surface is enriched in the heavier atomic components relative to the lighter ones. This material is incorporated into the heavily radiation-damaged outer surfaces of grains where it is subject to resputtering. Over the course of several hundred years an equilibrium surface layer, enriched in heavier atoms, is found to form. The dependence of the calculated results upon the sputtering rate and on the details of the energy spectrum of sputtered particles is investigated. It is concluded that mass fractionation by solar wind sputtering is likely to be an important phenomenon on the lunar surface.

  4. SPUTTERING FROM A POROUS MATERIAL BY PENETRATING IONS

    SciTech Connect

    Rodriguez-Nieva, J. F.; Bringa, E. M.; Cassidy, T. A.; Caro, A.; Loeffler, M. J.; Farkas, D.

    2011-12-10

    Porous materials are ubiquitous in the universe and weathering of porous surfaces plays an important role in the evolution of planetary and interstellar materials. Sputtering of porous solids in particular can influence atmosphere formation, surface reflectivity, and the production of the ambient gas around materials in space. Several previous studies and models have shown a large reduction in the sputtering of a porous solid compared to the sputtering of the non-porous solid. Using molecular dynamics simulations we study the sputtering of a nanoporous solid with 55% of the solid density. We calculate the electronic sputtering induced by a fast, penetrating ion, using a thermal spike representation of the deposited energy. We find that sputtering for this porous solid is, surprisingly, the same as that for a full-density solid, even though the sticking coefficient is high.

  5. 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.

  6. Dynamical simulation for sputtering of B 4C

    NASA Astrophysics Data System (ADS)

    Kenmotsu, T.; Kawamura, T.; Ono, T.; Yamamura, Y.

    1998-10-01

    Using ACAT-DIFFUSE code, we have simulated the fluence dependence of B 4C sputtering and the associated surface composition change under D + ion bombardment. The ACAT-DIFFUSE is a simulation code, which is based on a Monte Carlo method with a binary collision approximation and solves diffusion equations. In the case of near-threshold sputtering, the preferential sputtering of B atoms is enhanced by the threshold effect. As a result, the total sputtering yield at the steady state is reduced by about 20% compared with low-fluence sputtering. The surface concentration at steady state is determined by the competitive processes between diffusion and surface-atom removal due to sputtering. At normal incidence the interstitial diffusion contributes appreciably to the steady-state surface concentration, but at grazing incidence this effect is small. Therefore, the steady-state surface concentration ratio at grazing incidence is less than that of normal incidence.

  7. Investigation of neutral and ion dynamics in a HiPIMS plasma by tunable laser diode absorption spectroscopy (TDLAS)

    NASA Astrophysics Data System (ADS)

    Preissing, Patrick; Hecimovic, Ante; von Keudell, Achim

    2016-09-01

    High power impulse magnetron sputtering (HiPIMS) discharges are known for complex plasma interactions, and complex temporal and spatial dynamics. Spatial and temporal dynamic of argon metastable (Arm), Ti atom (Ti0) and Ti ion (Ti+) density and temperature is studied by an extended tunable diode laser absorption spectroscopy setup (TDLAS) during a HiPIMS pulse. The TDLAS setup used a beam expander in combination with a 6 photo diode array to simultaneously measure spatial (resolution 5 mm) and time resolved absorption profiles of an Arm, Ti0 and Ti+ transition. This in combination with moving the magnetron in axial direction gives a complete 2D map of the density evolution. Temporal resolution of 400 ns was achieved by recording the photo diode signal on the National Instruments card. Final results allowed to investigate temporal evolution of the observed species in the volume between the target and the substrate.

  8. Diode-like behavior of I-V curves of CoFe-(Al-O)/Si(100) granular thin films

    NASA Astrophysics Data System (ADS)

    Tuan Anh, Nguyen; Van Cuong, Giap; Anh Tuan, Nguyen

    2015-01-01

    In this study, the electrical performance of (Co70Fe30)x(Al-O)1-x (where x=0.1 and 0.3) granular thin films sputtered on Si(1 0 0) substrates, which were subsequently annealing at 350 °C for 1 h in vacuum, was investigated. The millimeter-sized samples were installed in an in-plane lateral Ag electrode configuration on the surface. The current-voltage (I-V) characteristics were measured in bias voltages of approximately ±7 V. The I-V curves demonstrated the so-called large Coulomb gaps and diode-like asymmetric behavior similar to a Zener diode-type rectification. This remarkable behavior was evaluated using the most suitable transport models. Results suggest that an effective magnetic diode could be fabricated from millimeter-sized magnetic granular thin films.

  9. Diode Structure for Microwave and Infrared Applications

    NASA Technical Reports Server (NTRS)

    Alcorn, George; Leinteran, Charles; Chiang, Bing

    1987-01-01

    Microwave signals switched or modulated optically. Planar diode with transparent cathode made in BaAs, Si, and InSb versions. Depending on specific configuration and material, such diode used for optical modulation of microwave signal or as infrared detector. Transparent cathode fabricated on GaAs diode so diode illuminates to generate and control short-circuit current.

  10. Formation of biocompatible surface layers depending on the sputtering distance

    NASA Astrophysics Data System (ADS)

    Nasakina, E. O.; Seregin, A. V.; Baikin, A. S.; Kaplan, M. A.; Konushkin, S. V.; Sergiyenko, K. V.; Kovaleva, E. D.; Kolmakova, A. A.; Leonov, A. V.; Sevost'yanov, M. A.; Kolmakov, A. G.; Simakov, S. V.

    2017-05-01

    Nano- and micro-dimensional surface layers of silver and tantalum on flat and wire NiTi substrates by the method of magnetron sputtering in vacuum were produced. The structure and composition of the samples were determined using SEM and Auger spectroscopy. With an increase in the sputtering distance, the thickness of the surface layers decreases, and the thickness of the transition layer and the dependence of the thickness change as a whole depend on the nature of the sputtered substance.

  11. Mechanisms of Excitation and Ionization Processes in Sputtering.

    DTIC Science & Technology

    2014-09-26

    PROCESSES IN SPUTTERING cFINAL REPORT In IGNATIUS S.T. TSONG AUGUST 7, 1985 OFFICE OF NAVAL RESEARCH CONTRACT NO. N00014-81-K-0844 CARIZONA STATE...interactions. To this end, we direct our investigation on the particles sputtered when a solid surface is subjected to energetic ion bombardment. An...understanding of the basic mechanisms will allow better interpretation of experimental data obtained by surface analytical techniques which make use of sputtering

  12. Energy and mass dependence of isotopic enrichment in sputtering

    SciTech Connect

    Shutthanandan, V.; Zhang, J.; Ray, Pradosh

    2003-05-01

    When a solid surface containing more than one component is bombarded by energetic particles, the sputtered flux is found to deviated from the stoichiometric composition of the target. This is known as preferential sputtering. Usually the sputtered flux is enriched with the lighter-mass particles, particularly at small emission angles. As the bombardment of the target is continued, the target surface becomes depleted in the particles that are preferentially emitted and a steady state is eventually established, where the ratio of the sputtered particles becomes equal to the natural abundance ratio of the particles in the target.

  13. Low energy sputtering of cobalt by cesium ions

    NASA Technical Reports Server (NTRS)

    Handoo, A.; Ray, Pradosh K.

    1989-01-01

    An experimental facility to investigate low energy (less than 500 eV) sputtering of metal surfaces with ions produced by an ion gun is described. Results are reported on the sputtering yield of cobalt by cesium ions in the 100 to 500 eV energy range at a pressure of 1 times 10(exp -6) Torr. The target was electroplated on a copper substrate. The sputtered atoms were collected on a cobalt foil surrounding the target. Co-57 was used as a tracer to determine the sputtering yield.

  14. Sputter deposition of lithium silicate - lithium phosphate amorphous electrolytes

    SciTech Connect

    Dudney, N.J.; Bates, J.B.; Luck, C.F. ); Robertson, J.D. . Dept. of Chemistry)

    1991-01-01

    Thin films of an amorphous lithium-conducting electrolyte were deposited by rf magnetron sputtering of ceramic targets containing Li{sub 4}SiO{sub 4} and Li{sub 3}PO{sub 4}. The lithium content of the films was found to depend more strongly on the nature and composition of the targets than on many other sputtering parameters. For targets containing Li{sub 4}SiO{sub 4}, most of the lithium was found to segregate away from the sputtered area of the target. Codeposition using two sputter sources achieves a high lithium content in a controlled and reproducible film growth. 10 refs., 4 figs.

  15. Nanofluidic osmotic diodes

    NASA Astrophysics Data System (ADS)

    Bocquet, Lyderic; Picallo, Clara; Gravelle, Simon; Joly, Laurent; Charlaix, Elisabeth

    2013-11-01

    Osmosis describes the flow of water across semipermeable membranes powered by the chemical free energy extracted from salinity gradients. While osmosis can be expressed in simple terms via the van't Hoff ideal gas formula for the osmotic pressure, it is a complex phenomenon taking its roots in the subtle interactions occurring at the scale of the membrane nanopores. Here we use new opportunities offered by nanofluidic systems to create an osmotic diode exhibiting asymmetric water flow under reversal of osmotic driving. We show that a surface charge asymmetry built on a nanochannel surface leads to non-linear couplings between water flow and the ion dynamics, which are capable of water flow rectification. This phenomenon opens new opportunities for water purification and complex flow control in nanochannels.

  16. Emitron: microwave diode

    DOEpatents

    Craig, G.D.; Pettibone, J.S.; Drobot, A.T.

    1982-05-06

    The invention comprises a new class of device, driven by electron or other charged particle flow, for producing coherent microwaves by utilizing the interaction of electromagnetic waves with electron flow in diodes not requiring an external magnetic field. Anode and cathode surfaces are electrically charged with respect to one another by electron flow, for example caused by a Marx bank voltage source or by other charged particle flow, for example by a high energy charged particle beam. This produces an electric field which stimulates an emitted electron beam to flow in the anode-cathode region. The emitted electrons are accelerated by the electric field and coherent microwaves are produced by the three dimensional spatial and temporal interaction of the accelerated electrons with geometrically allowed microwave modes which results in the bunching of the electrons and the pumping of at least one dominant microwave mode.

  17. White light emitting diodes

    NASA Astrophysics Data System (ADS)

    Baur, J.; Schlotter, P.; Schneider, J.

    Using blue-emitting GaN LEDs on SiC substrate chips as primary light sources, we have fabricated green, yellow, red and white light emitting diodes (LUCOLEDs). The generation of mixed colors, as turquoise and magenta, is also demonstrated. The underlying physical principle is that of luminescence downconversion (Stokes shift), as typical for organic dye molecules and many inorganic phosphors. For white light generation via the LUCOLED principle, the phosphor Y3Al5O12:Ce3+(4f1) is ideally suited. The optical characteristics of Ce3+(4f1) in Y3Al5O12(YAG) are discussed in detail. Possibilities to "tune" the white color by various substitutions in the garnet lattice are shortly outlined.

  18. Laterally injected light-emitting diode and laser diode

    SciTech Connect

    Miller, Mary A.; Crawford, Mary H.; Allerman, Andrew A.

    2015-06-16

    A p-type superlattice is used to laterally inject holes into an III-nitride multiple quantum well active layer, enabling efficient light extraction from the active area. Laterally-injected light-emitting diodes and laser diodes can enable brighter, more efficient devices that impact a wide range of wavelengths and applications. For UV wavelengths, applications include fluorescence-based biological sensing, epoxy curing, and water purification. For visible devices, applications include solid state lighting and projection systems.

  19. Measuring size dependent electrical properties from nanoneedle structures: Pt/ZnO Schottky diodes

    SciTech Connect

    Mao, Shimin; Anderson, Daniel D.; Shang, Tao; Park, Byoungnam; Dillon, Shen J.

    2014-04-14

    This work reports the fabrication and testing of nanoneedle devices with well-defined interfaces that are amenable to a variety of structural and electrical characterization, including transmission electron microscopy. Single Pt/ZnO nanoneedle Schottky diodes were fabricated by a top down method using a combination of electro-polishing, sputtering, and focused ion beam milling. The resulting structures contained nanoscale planar heterojunctions with low ideality factors, the dimensions of which were tuned to study size-dependent electrical properties. The diameter dependence of the Pt/ZnO diode barrier height is explained by a joule heating effect and/or electronic inhomogeneity in the Pt/ZnO contact area.

  20. Design and manufacture of sputtered multilayers for applications to soft X-ray optics

    NASA Astrophysics Data System (ADS)

    Houdy, Ph.; Boher, P.

    1994-09-01

    Nanometer scale multilayers has been deposited using high vacuum diode rf sputtering chamber equipped with in situ kinetic ellipsometers. The influence of the composition, the roughness, the interface layer and the number of periods have been studied in order to optimize the stacks for soft X-ray reflection. The behaviour of the structures under thermal annealing has been observed. At last, gratings have been successfully manufactured. Des muticouches nanométriques ont été déposées par pulvérisation diode rf ultravide dans une chambre équipée d'ellipsomètres in situ. L'influence de la composition, de la rugosité, de la présence d'une couche d'interface et du nombre de périodes a été estimée afin d'optimiser les empilements pour la réflexion de rayons X mous. Le comportement de ces structures sous recuit thermique a été observé. Enfin des réseaux ont été réalisés avec succès.

  1. Thermometric Property of a Diode.

    ERIC Educational Resources Information Center

    Inman, Fred W.; Woodruff, Dan

    1995-01-01

    Presents a simple way to implement the thermometric property of a semiconductor diode to produce a thermometer with a nearly linear dependence upon temperature over a wide range of temperatures. (JRH)

  2. Enhanced vbasis laser diode package

    DOEpatents

    Deri, Robert J.; Chen, Diana; Bayramian, Andy; Freitas, Barry; Kotovsky, Jack

    2014-08-19

    A substrate having an upper surface and a lower surface is provided. The substrate includes a plurality of v-grooves formed in the upper surface. Each v-groove includes a first side and a second side perpendicular to the first side. A laser diode bar assembly is disposed within each of the v-grooves and attached to the first side. The laser diode bar assembly includes a first adhesion layer disposed on the first side of the v-groove, a metal plate attached to the first adhesion layer, a second adhesion layer disposed over the metal plate, and a laser diode bar attached to the second adhesion layer. The laser diode bar has a coefficient of thermal expansion (CTE) substantially similar to that of the metal plate.

  3. Thermometric Property of a Diode.

    ERIC Educational Resources Information Center

    Inman, Fred W.; Woodruff, Dan

    1995-01-01

    Presents a simple way to implement the thermometric property of a semiconductor diode to produce a thermometer with a nearly linear dependence upon temperature over a wide range of temperatures. (JRH)

  4. Pump Diode Characterization for an Unstable Diode-Pumped Alkali Laser Resonator

    DTIC Science & Technology

    2013-03-01

    PUMP DIODE CHARACTERIZATION FOR AN UNSTABLE DIODE - PUMPED ALKALI LASER RESONATOR THESIS Chad T. Taguba, Master Sergeant, USAF AFIT-ENP-13-M-33...not subject to copyright protection in the United States. AFIT-ENP-13-M-33 PUMP DIODE CHARACTERIZATION FOR AN UNSTABLE DIODE - PUMPED ALKALI LASER ... DIODE CHARACTERIZATION FOR AN UNSTABLE DIODE - PUMPED ALKALI LASER RESONATOR Approved: Chad T. Taguba, BS Master Sergeant, USAF

  5. A Multipactor Discharge in Crossed Fields Under the Conditions of a Combination of Two Waves with Close Frequencies

    NASA Astrophysics Data System (ADS)

    Ilyakov, E. V.; Kulagin, I. S.

    2013-09-01

    We study the multipactor discharge in crossed fields, specifically, a microwave electric field and a quasistatic magnetic field. The multipactor occurs under the conditions of superposition of two microwave pulses with close frequencies, which correspond to the three-centimeter wavelength range. Experiments in the rectangular waveguide demonstrate that the multipactor develops and exists in a wide range of differences in the signal frequencies, which covers on interval of up to 700 MHz. The specific power absorbed in the discharge is equal to several kW/cm2, and the radiation is absorbed efficiently at both frequencies. When the signal power is initially insufficient to ensure the multipactor development, an additional signal at a close frequency allows one to switch the discharge, which absorbs microwaves efficiently, on and off. At a frequency difference of up to 40 MHz, the achieved switch-on time is about 100 ns. Switch-on of the second signal in the line with a resonator cavity, which has a frequency belonging to the cavity frequency band, also results in the discharge development and switches the cavity from the transition regime to the reflection regime.

  6. Direct measurements and modeling of gradient-aligned cross-field ion flows near an absorbing boundary

    NASA Astrophysics Data System (ADS)

    Thompson, D. S.; Siddiqui, M. Umair; McIlvain, J. S.; Short, Z. D.; Scime, E. E.; Aguirre, E. M.; Henriquez, M. F.; McKee, J. S.

    2015-11-01

    Direct measurements of cross-field ion transport near boundaries are sought for validating transport models in magnetically confined plasmas. Using laser-induced fluorescence, we measured ion flows normal to an absorbing boundary that was aligned to be parallel to a uniform axial magnetic field in a helicon plasma. We used Langmuir and emissive probes to measure local density, temperature and plasma potential profiles in the same region. We then scanned ion-neutral collisionality by varying the ratio of the ion gyro-radius, ρi, and ion-neutral collision length, λ, over the range 0.34 <=ρi / λ <= 1.60. Classical diffusion along density and potential gradients is sufficient to describe flow profiles for most cases but did not describe measurements well for 0.44 <=ρi / λ <= 0.65. In these cases, cross-sections ~3 times the classical prediction produced acceptable fits, and flow to the boundary was enhanced significantly. These enhanced flow cases exhibit spectra with low-frequency electrostatic fluctuations (f <10 kHz) that are not observed in data described well by a classical diffusion model. This work is supported by US National Science Foundation grant number PHY-1360278.

  7. The role of the density gradient on intermittent cross-field transport events in a simple magnetized toroidal plasma

    SciTech Connect

    Theiler, C.; Diallo, A.; Fasoli, A.; Furno, I.; Labit, B.; Ricci, P.; Podesta, M.; Poli, F. M.

    2008-04-15

    Intermittent cross-field particle transport events (ITEs) are studied in the basic toroidal device TORPEX [TORoidal Plasma EXperiment, A. Fasoli et al., Phys. Plasmas 13, 055902 (2006)], with focus on the role of the density gradient. ITEs are due to the intermittent radial elongation of an interchange mode. The elongating positive wave crests can break apart and form blobs. This is not necessary, however, for plasma particles to be convected a considerable distance across the magnetic field lines. Conditionally sampled data reveal two different scenarios leading to ITEs. In the first case, the interchange mode grows radially from a slab-like density profile and leads to the ITE. A novel analysis technique reveals a monotonic dependence between the vertically averaged inverse radial density scale length and the probability for a subsequent ITE. In the second case, the mode is already observed before the start of the ITE. It does not elongate radially in a first stage, but at a later time. It is shown that this elongation is preceded by a steepening of the density profile as well.

  8. Experimental Evidence of Change in Sheath Properties due to Secondary Electron Emission in a Crossed Field Plasma Setup

    NASA Astrophysics Data System (ADS)

    Sawlani, Kapil; Foster, John

    2013-09-01

    The nature of plasma transport across the magnetic field in crossed-field (CF) devices remains largely an unsolved problem. This can be further complicated by the presence of secondary electrons derived from electron impact on walls. The coupling of these electrons to the bulk plasma and their role in CF plasma transport is also not well understood. The emission of secondary electrons from wall surfaces also affects the sheath potential, thus impacting energy transport to the wall. In this work, a benchtop apparatus is used to elucidate the role that secondary electrons play in regards to CF transport and energy flow to the walls. An electron beam is used to generate a secondary electron plume at the surface of an insulating target. The CF device plasma response to these secondary electrons is assessed by measuring changes to the potential distribution in the sheath of the irradiated target and the measured electron energy distribution function. The variation in the discharge voltage at fixed emission current is also determined which yields insight into CF impedance. The effect of the variation of the electron beam's angle of incidence on the CF current is also characterized. An attempt is made to relate phenomena and trends observed in this work with those in Hall thrusters. Work supported by Air Force Office of Scientific Research (AFOSR).

  9. [The medical assistance of Swedish Red Cross Field Hospital in Busan during and after the Korean war].

    PubMed

    Park, Jiwook

    2010-06-30

    After the outbreak of the Korean war, the Kingdom of Sweden, a permanent neutral nation, dispatched the Swedish Red Cross Field Hospital(SRCFH) instead of armed forces for humanitarian support to the allied forces in South Korea. The Hospital consisted of about 170 Swedes, all volunteers. From the early part of the Korean War, SRCFH took part in the medical assistance in Busan. When the frontline advanced to northern Korea, the number of inflowing casualties to this field hospital decreased. At that time, earnest medical aid for civilians commenced, and many Koreans were treated in available beds in SRCFH. After the armistice in July 1953, SRCFH became the Swedish Hospital in Busan, serving not only the military but also civilians, and continued its humanitarian mission until April 1957 for the Korean who were suffering from a collapsed medical system in the midst of war. When the Hospital returned to Sweden, it had treated over two million patients from twenty countries, including wounded UN allied force, Korean (south and north), Chinese prisoner of war and Korean civilian. Moreover, it left a transformative legacy, the National Medical Center in Seoul which was established in collaboration with other Scandinavian countries who dispatched medical assistance during the Korean War.

  10. Comparative study of cross-field and field-aligned electron beams in active experiments. [in upper atmosphere

    NASA Technical Reports Server (NTRS)

    Winglee, R. M.; Pritchett, P. L.

    1988-01-01

    Beam-plasma interactions associated with the cross-field and field-aligned injection of electron beams from spacecraft were investigated using a two-dimensional (three velocity component) electrostatic particle simulations. It is shown that the beam properties and plasma response can be characterized well by the ratio between the stagnation time and the plasma response time, which depends on the ratio of the ambient plasma density to the beam density, the beam width, the beam energy, and the spacecraft length. It was found that the beams injected across the field lines tend to lose their coherence after about one or two gyrations due to space-charge oscillations induced by the beam, irrespective of the spacecraft charging. These oscillations scatter the beam electrons into a hollow cylinder of a radius equal to a beam electron gyroradius and thickness of the order of two beam Debye lengths. Parallel injected beams are subjected to similar oscillations, which cause the beam to expand to fill a solid cylinder of a comparable thickness.

  11. Thermal conductivity of sputtered amorphous Ge films

    SciTech Connect

    Zhan, Tianzhuo; Xu, Yibin; Goto, Masahiro; Tanaka, Yoshihisa; Kato, Ryozo; Sasaki, Michiko; Kagawa, Yutaka

    2014-02-15

    We measured the thermal conductivity of amorphous Ge films prepared by magnetron sputtering. The thermal conductivity was significantly higher than the value predicted by the minimum thermal conductivity model and increased with deposition temperature. We found that variations in sound velocity and Ge film density were not the main factors in the high thermal conductivity. Fast Fourier transform patterns of transmission electron micrographs revealed that short-range order in the Ge films was responsible for their high thermal conductivity. The results provide experimental evidences to understand the underlying nature of the variation of phonon mean free path in amorphous solids.

  12. Sputtered protective coatings for die casting dies

    NASA Technical Reports Server (NTRS)

    Mirtich, M. J.; Nieh, C. Y.; Wallace, J. F.

    1981-01-01

    This investigation determined whether selected ion beam sputtered coatings on H-13 die steel would have the potential of improving the thermal fatigue behavior of the steel used as a die in aluminum die casting. The coatings were selected to test candidate insulators and metals capable of providing protection of the die surface. The studies indicate that 1 micrometer thick W and Pt coatings reduced the thermal fatigue more than any other coating tested and are candidates to be used on a die surface to increase die life.

  13. System analysis of plasma centrifuges and sputtering

    NASA Technical Reports Server (NTRS)

    Hong, S. H.

    1978-01-01

    System analyses of cylindrical plasma centrifuges are presented, for which the velocity field and electromagnetic fields are calculated. The effects of different electrode geometrics, induced magnetic fields, Hall-effect, and secondary flows are discussed. It is shown that speeds of 10000 m/sec can be achieved in plasma centrifuges, and that an efficient separation of U238 and U235 in uranium plasmas is feasible. The external boundary-value problem for the deposition of sputtering products is reduced to a Fredholm integral equation, which is solved analytically by means of the method of successive approximations.

  14. Reactive sputter deposition of boron nitride

    SciTech Connect

    Jankowski, A.F.; Hayes, J.P.; McKernan, M.A.; Makowiecki, D.M.

    1995-10-01

    The preparation of fully dense, boron targets for use in planar magnetron sources has lead to the synthesis of Boron Nitride (BN) films by reactive rf sputtering. The deposition parameters of gas pressure, flow and composition are varied along with substrate temperature and applied bias. The films are characterized for composition using Auger electron spectroscopy, for chemical bonding using Raman spectroscopy and for crystalline structure using transmission electron microscopy. The deposition conditions are established which lead to the growth of crystalline BN phases. In particular, the growth of an adherent cubic BN coating requires 400--500 C substrate heating and an applied {minus}300 V dc bias.

  15. Photovoltaic performance of Gallium-doped ZnO thin film/Si nanowires heterojunction diodes

    NASA Astrophysics Data System (ADS)

    Akgul, Guvenc; Aksoy Akgul, Funda; Emrah Unalan, Husnu; Turan, Rasit

    2016-04-01

    In this work, photovoltaic performance of Ga-doped ZnO thin film/Si NWs heterojunction diodes was investigated. Highly dense and vertically well-aligned Si NW arrays were successfully synthesised on a p-type (1 0 0)-oriented Si wafer through cost-effective metal-assisted chemical etching technique. Ga-doped ZnO thin films were deposited onto Si NWs via radio frequency magnetron sputtering to construct three-dimensional heterostructures. Photovoltaic characteristics of the fabricated diodes were determined with current density (J)-voltage (V) measurements under simulated solar irradiation of AM 1.5 G. The optimal open-circuit voltage, short-circuit current density, fill factor and power conversion efficiency were found to be 0.37 V, 3.30 mA cm-2, 39.00 and 0.62%, respectively. Moreover, photovoltaic diodes exhibited relatively high external quantum efficiency over the broadband wavelengths between 350 and 1100 nm interval of the spectrum. The observed photovoltaic performance in this study clearly indicates that the investigated device structure composed of Ga-doped ZnO thin film/Si NWs heterojunctions could facilitate an alternative pathway for optoelectronic applications in future, and be a promising alternative candidate for high-performance low-cost new-generation photovoltaic diodes.

  16. Improving the efficiency of high-power diode lasers using diamond heat sinks

    SciTech Connect

    Parashchuk, Valentin V; Baranov, V V; Telesh, E V; Mien, Vu Doan; Luc, Vu Van; Truong, Pham Van; Belyaeva, A K

    2010-06-23

    Using multifunctional ion beam and magnetron sputtering systems, we have developed chemical and vacuum techniques for producing metallic coatings firmly adherent to various surfaces, with application to copper and diamond heat sinks for diode lasers. Conditions have been optimised for mounting diode lasers and bars using the proposed metallisation processes, and significant improvements in the output parameters of the devices have been achieved. The power output of cw laser diodes on diamond heat sinks increases by up to a factor of 2, the linear (working) portion of their power-current characteristic becomes markedly broader, and their slope efficiency increases by a factor of 1.5 - 2 relative to that of lasers on copper heat spreaders. The use of diamond heat sinks extends the drive current range of pulsed diode bars by a factor of 2 - 3 and enables them to operate at more than one order of magnitude longer pump pulse durations (up to milliseconds) when the pulse repetition rate is at least 10 Hz. (lasers)

  17. Comparison of the Sputter Rates of Oxide Films Relative to the Sputter Rate of SiO2

    SciTech Connect

    Baer, Donald R.; Engelhard, Mark H.; Lea, Alan S.; Nachimuthu, Ponnusamy; Droubay, Timothy C.; Kim, J.; Lee, B.; Mathews, C.; Opila, R. L.; Saraf, Laxmikant V.; Stickle, William F.; Wallace, Robert; Wright, B. S.

    2010-09-02

    Because of the increasing technological importance of oxide films for a variety of applications, there is a growing interest in knowing the sputter rates for a wide variety of oxides. To support needs of users of the Environmental Molecular Sciences Laboratory (EMSL) User facility as well as our research programs, we have made a series of measurements of the sputter rates for oxide films that have been grown by oxygen plasma assisted molecular beam epitaxy (OPA-MBE), pulsed laser deposition (PLD), Atomic Layer Deposition (ALD), electrochemical oxidation, or sputter deposition. The sputter rates for these oxide films were determined in comparison to the sputter rates for thermally grown SiO2, a common sputter rate reference material. The film thicknesses and densities of these films were usually measured using x-ray reflectivity (XRR). These samples were mounted in an x-ray photoelectron spectroscopy (XPS) system or an Auger electron spectrometer for sputtering measurements using argon ion sputtering. Although the primary objective was to determine relative sputter rates at a fixed angle, the measurements were also used to determine: i) the angle dependence of the relative sputter rates; ii) the energy dependence of the relative sputter rates; and iii) the extent of ion beam reduction for the various oxides. Materials examined include: SiO2 (reference films), Al2O3, CeO2, Cr2O3, Fe2O3, HfO2, ITO (In-Sn-oxide) Ta2O5, TiO2 (anatase and rutile) and ZnO. We find that the sputter rates for the oxides can vary up to a factor of two (usually slower) from that observed for SiO2. The ratios of sputter rates to SiO2 appear to be relatively independent of ion beam energy for the range of 1kV to 4 kV and for incident angles of less than 50º. As expected, the ion beam reduction of the oxides varies with the sputter angle. These studies demonstrate that we can usually obtain sputter rate reproducibility better than 5% for similar oxide films.

  18. Excitation of Nb, Ta, and W atoms in sputtering processes

    SciTech Connect

    Vasil`eva, E.K.; Morozov, S.N.

    1995-12-01

    Optical emission spectra of sputtered atoms that arise under the bombardment of Nb, Ta, and W surfaces by xenon ions with an energy of 40 keV are studied in the wavelength range of 380 - 600 nm. The properties and mechanisms of the formation of excited atomic states in sputtering processes are discussed. 12 refs., 3 figs.

  19. Apparatus for and method of controlling sputter coating

    SciTech Connect

    Boys, R.

    1985-02-19

    The magnetic field of a magnetron sputter coating apparatus is controlled in response to measurements of plasma parameters to control deposition parameters, such as sputter deposition rate and material deposition thickness profile. From time to time the apparatus is standardized to change preset values for parameters of the plasma to manage the deposition parameters.

  20. Electrochromism in sputtered WO{sub 3} thin films

    SciTech Connect

    Batchelor, R.A.; Burdis, M.S.; Siddle, J.R.

    1996-03-01

    There are large variations in the properties of WO{sub 3} sputtered under different conditions and two samples sputtered from an oxide target and reactively sputtered from a metal target were compared in detail. The thin film sputtered from an oxide target was found to color and bleach rapidly in 1 M LiClO{sub 4} in propylene carbonate, while the thin film reactively sputtered from a metal target could be colored deeply, but bleached only slowly. By calculating the rate of change of optical density during cyclic voltammetry, it was possible to directly compare the coloration response with the current/voltage behavior of the electrodes. In both cases at least two lithium insertion reactions appear to occur. The distinction between the two reactions was especially clear in the sample sputtered from a metal target, in which an insertion of high electrochromic efficiency occurred up to Li{sub 0.2}WO{sub 3} and then an insertion of considerably lower electrochromic efficiency up to Li{sub 0.5}WO{sub 3}. Although a small amount of coloration and bleaching continued to occur after switching the reactively sputtered sample to open circuit during the coloration and bleaching cycles; transmission change was largely halted by disconnecting the external current supply. The slow end to the bleach of the reactively sputtered sample corresponded to a reaction of high electrochromic efficiency.

  1. Fluence-dependent sputtering yield of micro-architectured materials

    NASA Astrophysics Data System (ADS)

    Matthes, Christopher S. R.; Ghoniem, Nasr M.; Li, Gary Z.; Matlock, Taylor S.; Goebel, Dan M.; Dodson, Chris A.; Wirz, Richard E.

    2017-06-01

    We present an experimental examination of the relationship between the surface morphology of Mo and its instantaneous sputtering rate as function of low-energy plasma ion fluence. We quantify the dynamic evolution of nano/micro features of surfaces with built-in architecture, and the corresponding variation in the sputtering yield. Ballistic deposition of sputtered atoms as a result of geometric re-trapping is observed, and re-growth of surface layers is confirmed. This provides a self-healing mechanism of micro-architectured surfaces during plasma exposure. A variety of material characterization techniques are used to show that the sputtering yield is not a fundamental property, but that it is quantitatively related to the initial surface architecture and to its subsequent evolution. The sputtering yield of textured molybdenum samples exposed to 300 eV Ar plasma is roughly 1/2 of the corresponding value for flat samples, and increases with ion fluence. Mo samples exhibited a sputtering yield initially as low as 0.22 ± 5%, converging to 0.4 ± 5% at high fluence. The sputtering yield exhibits a transient behavior as function of the integrated ion fluence, reaching a steady-state value that is independent of initial surface conditions. A phenomenological model is proposed to explain the observed transient sputtering phenomenon, and to show that the saturation fluence is solely determined by the initial surface roughness.

  2. A new technique for measuring sputtering yields at high energies

    NASA Technical Reports Server (NTRS)

    Qiu, Y.; Griffith, J. E.; Tombrello, T. A.

    1984-01-01

    The use of thin, self-supporting carbon catcher foils allows one to measure sputtering yields in a broad range of materials with high sensitivity. Analyzing the foils with Rutherford forward scattering, sputtered Al, Si and P surface densities down to 5 x 10 to the 13th per sq cm with uncertainties of about 20 percent have been measured.

  3. Dynamic observation of cone formation on Cu by ion sputtering

    NASA Astrophysics Data System (ADS)

    Goto, K.; Suzuki, K.

    1988-06-01

    Cone formation on Cu due to ion sputtering was observed dynamically in a scanning electron microscope with a 16-mm movie camera without interrupting the sputtering process. 3-keV argon ions were used for sputtering at an ambient temperature. Cones formed in a polycrystalline sample of Cu for both cases with and without a molybdenum seeding material (after Wehner), while no cones were found for a single crystal Cu(111) surface even with the seeding material. The use of the seeding material resulted in sharp edge (cliff) between the sputtered region and unsputtered region shadowed by the seeding material. Further simultaneous sputtering of the both areas by removing the seeding material formed another cones at the cliff and the sputtered atoms from the cliff sputtered the cones formerly formed just below the cliff. Then quick recess of the latter cones was observed. This revealed that not only incident ions but also the sputtered atoms take a significant role in the cone formation. Slip-like morphological changes due to ion bombardment of the seeding material were also observed.

  4. Low-frequency noise properties in Pt-indium gallium zinc oxide Schottky diodes

    SciTech Connect

    Zhang, Jiawei; Zhang, Linqing; Ma, Xiaochen; Wilson, Joshua; Jin, Jidong; Du, Lulu; Xin, Qian; Song, Aimin

    2015-08-31

    The low-frequency noise properties of Pt-indium gallium zinc oxide (IGZO) Schottky diodes at different forward biases are investigated. The IGZO layer and Pt contact were deposited by RF sputtering at room temperature. The diode showed an ideality factor of 1.2 and a barrier height of 0.94 eV. The current noise spectral density exhibited 1/f behavior at low frequencies. The analysis of the current dependency of the noise spectral density revealed that for the as-deposited diode, the noise followed Luo's mobility and diffusivity fluctuation model in the thermionic-emission-limited region and Hooge's empirical theory in the series-resistance-limited region. A low Hooge's constant of 1.4 × 10{sup −9} was found in the space-charge region. In the series-resistance-limited region, the Hooge's constant was 2.2 × 10{sup −5}. After annealing, the diode showed degradation in the electrical performance. The interface-trap-induced noise dominated the noise spectrum. By using the random walk model, the interface-trap density was obtained to be 3.6 × 10{sup 15 }eV{sup −1 }cm{sup −2}. This work provides a quantitative approach to analyze the properties of Pt-IGZO interfacial layers. These low noise properties are a prerequisite to the use of IGZO Schottky diodes in switch elements in memory devices, photosensors, and mixer diodes.

  5. Sputter-deposited fuel cell membranes and electrodes

    NASA Technical Reports Server (NTRS)

    Narayanan, Sekharipuram R. (Inventor); Jeffries-Nakamura, Barbara (Inventor); Chun, William (Inventor); Ruiz, Ron P. (Inventor); Valdez, Thomas I. (Inventor)

    2001-01-01

    A method for preparing a membrane for use in a fuel cell membrane electrode assembly includes the steps of providing an electrolyte membrane, and sputter-depositing a catalyst onto the electrolyte membrane. The sputter-deposited catalyst may be applied to multiple sides of the electrolyte membrane. A method for forming an electrode for use in a fuel cell membrane electrode assembly includes the steps of obtaining a catalyst, obtaining a backing, and sputter-depositing the catalyst onto the backing. The membranes and electrodes are useful for assembling fuel cells that include an anode electrode, a cathode electrode, a fuel supply, and an electrolyte membrane, wherein the electrolyte membrane includes a sputter-deposited catalyst, and the sputter-deposited catalyst is effective for sustaining a voltage across a membrane electrode assembly in the fuel cell.

  6. Mixed composition materials suitable for vacuum web sputter coating

    NASA Technical Reports Server (NTRS)

    Banks, Bruce A.; Rutledge, Sharon K.; Dever, Joyce A.; Bruckner, Eric J.; Walters, Patricia; Hambourger, Paul D.

    1996-01-01

    Ion beam sputter deposition techniques were used to investigate simultaneous sputter etching of two component targets so as to produce mixed composition films. Although sputter deposition has been largely confined to metals and metal oxides, at least one polymeric material, poly-tetra-fluorethylene, has been demonstrated to produce sputtered fragments which repolymerize upon deposition to produce a highly cross-linked fluoropolymer resembling that of the parent target Fluoropolymer-filled silicon dioxide and fluoropolymer-filled aluminum oxide coatings have been deposited by means of ion beam sputter coat deposition resulting in films having material properties suitable for aerospace and commercial applications. The addition of fluoropolymer to silicon dioxide films was found to increase the hydrophobicity of the resulting mixed films; however, adding fluoropolymer to aluminum oxide films resulted in a reduction in hydrophobicity, thought to be caused by aluminum fluoride formation.

  7. Monte Carlo simulations of nanoscale focused neon ion beam sputtering.

    PubMed

    Timilsina, Rajendra; Rack, Philip D

    2013-12-13

    A Monte Carlo simulation is developed to model the physical sputtering of aluminum and tungsten emulating nanoscale focused helium and neon ion beam etching from the gas field ion microscope. Neon beams with different beam energies (0.5-30 keV) and a constant beam diameter (Gaussian with full-width-at-half-maximum of 1 nm) were simulated to elucidate the nanostructure evolution during the physical sputtering of nanoscale high aspect ratio features. The aspect ratio and sputter yield vary with the ion species and beam energy for a constant beam diameter and are related to the distribution of the nuclear energy loss. Neon ions have a larger sputter yield than the helium ions due to their larger mass and consequently larger nuclear energy loss relative to helium. Quantitative information such as the sputtering yields, the energy-dependent aspect ratios and resolution-limiting effects are discussed.

  8. Plasma debris sputter resistant x-ray mirror.

    PubMed

    Amano, Sho; Inoue, Tomoaki; Harada, Tetsuo

    2013-06-01

    A diamond-like carbon (DLC) mirror, used as a grazing incident mirror in a plasma x-ray source, exhibits a high resistance to plasma debris sputtering. Good mirror reflectivity at a wavelength of 13.5 nm was confirmed using synchrotron radiation at the NewSUBARU facility. The erosion rate due to plasma debris sputtered at the incident debris angle of 20° was measured using a laser-produced Xe plasma source developed by the authors. The results indicate that the DLC film has a 5- and 15-fold higher sputtering resistance compared to films made of the traditional mirror materials Ru and Au, respectively. Because the DLC mirror retains a high sputtering resistance to Sn ions, it may be effective in Sn plasma source applications. We conclude that a grazing incident x-ray mirror coated with DLC can be of use as a plasma debris sputtering resistant mirror.

  9. Electron-beam activated thermal sputtering of thermoelectric materials.

    SciTech Connect

    Wu, J.; He, J.; Han, M-K.; Sootsman, J. R.; Girard, S.; Arachchige, I. U.; Kanatzidis, M. G.; Dravid, V. P.

    2011-08-01

    Thermoelectricity and Seebeck effect have long been observed and validated in bulk materials. With the development of advanced tools of materials characterization, here we report the first observation of such an effect in the nanometer scale: in situ directional sputtering of several thermoelectric materials inside electron microscopes. The temperature gradient introduced by the electron beam creates a voltage-drop across the samples, which enhances spontaneous sputtering of specimen ions. The sputtering occurs along a preferential direction determined by the direction of the temperature gradient. A large number of nanoparticles form and accumulate away from the beam location as a result. The sputtering and re-crystallization are found to occur at temperatures far below the melting points of bulk materials. The sputtering occurs even when a liquid nitrogen cooling holder is used to keep the overall temperature at -170 C. This unique phenomenon that occurred in the nanometer scale may provide useful clues to understanding the mechanism of thermoelectric effect.

  10. Sputtering at grazing ion incidence: Influence of adatom islands

    SciTech Connect

    Rosandi, Yudi; Redinger, Alex; Michely, Thomas; Urbassek, Herbert M.

    2010-09-15

    When energetic ions impinge at grazing incidence onto an atomically flat terrace, they will not sputter. However, when adatom islands (containing N atoms) are deposited on the surface, they induce sputtering. We investigate this effect for the specific case of 83 deg. -incident 5 keV Ar ions on a Pt (111) surface by means of molecular-dynamics simulation and experiment. We find that - for constant coverage {Theta} - the sputter yield has a maximum at island sizes of N congruent with 10-20. A detailed picture explaining the decline of the sputter yield toward larger and smaller island sizes is worked out. Our simulation results are compared with dedicated sputtering experiments, in which a coverage of {Theta}=0.09 of Pt adatoms are deposited onto the Pt (111) surface and form islands with a broad distribution around a most probable size of N congruent with 20.

  11. Electron-beam activated thermal sputtering of thermoelectric materials

    SciTech Connect

    Wu Jinsong; Dravid, Vinayak P.; He Jiaqing; Han, Mi-Kyung; Sootsman, Joseph R.; Girard, Steven; Arachchige, Indika U.; Kanatzidis, Mercouri G.

    2011-08-15

    Thermoelectricity and Seebeck effect have long been observed and validated in bulk materials. With the development of advanced tools of materials characterization, here we report the first observation of such an effect in the nanometer scale: in situ directional sputtering of several thermoelectric materials inside electron microscopes. The temperature gradient introduced by the electron beam creates a voltage-drop across the samples, which enhances spontaneous sputtering of specimen ions. The sputtering occurs along a preferential direction determined by the direction of the temperature gradient. A large number of nanoparticles form and accumulate away from the beam location as a result. The sputtering and re-crystallization are found to occur at temperatures far below the melting points of bulk materials. The sputtering occurs even when a liquid nitrogen cooling holder is used to keep the overall temperature at -170 deg. C. This unique phenomenon that occurred in the nanometer scale may provide useful clues to understanding the mechanism of thermoelectric effect.

  12. Revibrational Spectra of Molecules Sputtered of Carbon Surfaces

    NASA Astrophysics Data System (ADS)

    Krstic, Predrag

    2008-10-01

    Irradiation of the carbon surfaces by hydrogen isotopes results in processes of crucial importance for the carbon based divertor tiles of a fusion reactor. Thus the sputtering and implantation, result in erosion, plasma pollution, and tritium retention, as well as carbon deposition all over the reactor first wall. The molecules chemically sputtered upon impact of deuterium of deuterated carbon surface are various hydrocarbons as well as We study the translational and rovibrational energy and angular spectra of sputtered molecules. The energy distributions of ejected molecules confirm the partial thermalization of the impact cascade. Sputtered hydrocarbon molecules have rovibrational energies in the range 1.5-2 eV, with relatively cold translational and rotational motion, close to 0.5 eV. In contrast, translational and rovibrational energies of sputtered deuterium molecules are close to 1 eV, with approximate equipartition between rotational and vibrational modes.

  13. Light Emitting Diodes (LEDs)

    NASA Technical Reports Server (NTRS)

    1997-01-01

    A special lighting technology was developed for space-based commercial plant growth research on NASA's Space Shuttle. Surgeons have used this technology to treat brain cancer on Earth, in two successful operations. The treatment technique, called Photodynamic Therapy, requires the surgeon to use tiny, pinhead-size Light Emitting Diodes (LEDs) (a source that releases long wavelengths of light ) to activate light-sensitive, tumor-treating drugs. 'A young woman operated on in May 1999 has fully recovered with no complications and no evidence of the tumor coming back,' said Dr. Harry Whelan, a pediatric neurologist at the Medical Hospital of Wisconsin in Milwaukee. Laser light has been used for this type of surgery in the past, but the LED light illuminates through all nearby tissues, reaching parts of a tumor that shorter wavelengths of laser light carnot. The new probe is safer because the longer wavelengths of light are cooler than the shorter wavelengths of laser light, making the LED less likely to injure normal brain tissue near the tumor. It can be used for hours at a time while still remaining cool to the touch. The LED light source is compact, about the size of a briefcase, and can be purchased for a fraction of the cost of a laser. The LEDs, developed and managed by NASA's Marshall Space Flight Center, have been used on seven Space Shuttle flights inside the Microgravity Astroculture Facility. This technology has also been successfully used to further commercial research in crop growth.

  14. Light Emitting Diodes (LEDs)

    NASA Technical Reports Server (NTRS)

    1997-01-01

    A special lighting technology was developed for space-based commercial plant growth research on NASA's Space Shuttle. Surgeons have used this technology to treat brain cancer on Earth, in two successful operations. The treatment technique, called Photodynamic Therapy, requires the surgeon to use tiny, pinhead-size Light Emitting Diodes (LEDs) (a source that releases long wavelengths of light ) to activate light-sensitive, tumor-treating drugs. 'A young woman operated on in May 1999 has fully recovered with no complications and no evidence of the tumor coming back,' said Dr. Harry Whelan, a pediatric neurologist at the Medical Hospital of Wisconsin in Milwaukee. Laser light has been used for this type of surgery in the past, but the LED light illuminates through all nearby tissues, reaching parts of a tumor that shorter wavelengths of laser light carnot. The new probe is safer because the longer wavelengths of light are cooler than the shorter wavelengths of laser light, making the LED less likely to injure normal brain tissue near the tumor. It can be used for hours at a time while still remaining cool to the touch. The LED light source is compact, about the size of a briefcase, and can be purchased for a fraction of the cost of a laser. The LEDs, developed and managed by NASA's Marshall Space Flight Center, have been used on seven Space Shuttle flights inside the Microgravity Astroculture Facility. This technology has also been successfully used to further commercial research in crop growth.

  15. Thermal conductivities of thin, sputtered optical films

    SciTech Connect

    Henager, C.H. Jr.; Pawlewicz, W.T.

    1991-05-01

    The normal component of the thin film thermal conductivity has been measured for the first time for several advanced sputtered optical materials. Included are data for single layers of boron nitride (BN), aluminum nitride (AIN), silicon aluminum nitride (Si-Al-N), silicon aluminum oxynitride (Si-Al-O-N), silicon carbide (SiC), and for dielectric-enhanced metal reflectors of the form Al(SiO{sub 2}/Si{sub 3}N{sub 4}){sup n} and Al(Al{sub 2}O{sub 3}/AIN){sup n}. Sputtered films of more conventional materials like SiO{sub 2}, Al{sub 2}O{sub 3}, Ta{sub 2}O{sub 5}, Ti, and Si have also been measured. The data show that thin film thermal conductivities are typically 10 to 100 times lower than conductivities for the same materials in bulk form. Structural disorder in the amorphous or very fine-grained films appears to account for most of the conductivity difference. Conclusive evidence for a film/substrate interface contribution is presented.

  16. Gas Sensing Diode Comprising SiC

    NASA Technical Reports Server (NTRS)

    Hunter, Gary William (Inventor)

    2001-01-01

    A diode for sensing hydrogen and hydrocarbons and the process for manufacturing the diode are disclosed. The diode is a Schottky diode which has a palladium chrome contact on the C-face of an n-type 6H Silicon carbide epilayer. The epilayer is grown on the C-face of a 6H silicon carbide substrate. The diode is capable of measuring low concentrations of hydrogen and hydrocarbons at high temperatures, for example, 800 degrees C. The diode is both sensitive and stable at elevated temperatures.

  17. Fabrication of a Schottky diode with transfer-free deposition of multilayer graphene on n-GaN by solid-phase reaction

    NASA Astrophysics Data System (ADS)

    Sahab Uddin, Md.; Ueno, Kazuyoshi

    2017-04-01

    Transfer-free deposition of multilayer graphene (MLG) on n-GaN by a solid-phase reaction was demonstrated for the first time for the fabrication of a Schottky diode. To improve the crystallinity and uniformity of MLG films, a new approach of heat sputtering for the deposition of amorphous carbon (C) and cobalt (Co) as catalyst layers has been investigated. The characteristics obtained by Raman spectroscopy and scanning electron microscopy (SEM) measurements revealed that the crystallinity and uniformity of MLG films were improved significantly by employing heat sputtering rather than conventional room-temperature sputtering. MLG–GaN Schottky diodes were fabricated with optimized deposition of MLG on n-GaN. The Schottky barrier height determined on the basis of the thermionic emission theory using current–voltage (I–V) data was 0.75 eV. The reverse leakage current was found to be of the order of 10‑7 A/mm2. The obtained results indicate the MLG fabrication on n-GaN by our proposed method might have potential applications in the fabrication of Schottky diodes.

  18. Carbon-Nanotube Schottky Diodes

    NASA Technical Reports Server (NTRS)

    Manohara, Harish; Wong, Eric; Schlecht, Erich; Hunt, Brian; Siegel, Peter

    2006-01-01

    Schottky diodes based on semiconducting single-walled carbon nanotubes are being developed as essential components of the next generation of submillimeter-wave sensors and sources. Initial performance predictions have shown that the performance characteristics of these devices can exceed those of the state-of-the-art solid-state Schottky diodes that have been the components of choice for room-temperature submillimeter-wave sensors for more than 50 years. For state-of-the-art Schottky diodes used as detectors at frequencies above a few hundred gigahertz, the inherent parasitic capacitances associated with their semiconductor junction areas and the resistances associated with low electron mobilities limit achievable sensitivity. The performance of such a detector falls off approximately exponentially with frequency above 500 GHz. Moreover, when used as frequency multipliers for generating signals, state-of-the-art solid-state Schottky diodes exhibit extremely low efficiencies, generally putting out only micro-watts of power at frequencies up to 1.5 THz. The shortcomings of the state-of-the-art solid-state Schottky diodes can be overcome by exploiting the unique electronic properties of semiconducting carbon nanotubes. A single-walled carbon nanotube can be metallic or semiconducting, depending on its chirality, and exhibits high electron mobility (recently reported to be approx.= 2x10(exp 5)sq cm/V-s) and low parasitic capacitance. Because of the narrowness of nanotubes, Schottky diodes based on carbon nanotubes have ultra-small junction areas (of the order of a few square nanometers) and consequent junction capacitances of the order of 10(exp -18) F, which translates to cutoff frequency >5 THz. Because the turn-on power levels of these devices are very low (of the order of nano-watts), the input power levels needed for pumping local oscillators containing these devices should be lower than those needed for local oscillators containing state-of-the-art solid

  19. Threshold energies of light-ion sputtering and heavy-ion sputtering as a function of angle of incidence

    NASA Astrophysics Data System (ADS)

    Yamamura, Y.

    1984-03-01

    The angular dependence of threshold energies has been investigated for light-ion sputtering and heavy-ion sputtering, and simple expressions for the angular dependences of threshold energies are derived for these two cases. For not-too-large angles of incidence, the threshold energy of heavy-ion sputtering is a decreasing function of the angle of incidence because of the anisotropy of the velocity distribution of recoil atoms, while the threshold energy of light-ion sputtering shows a weak angular dependence. For grazing angles of incidence, the threshold energies of these two cases are increasing functions of the angle of incidence because of surface scattering. In order to examine these theoretical angular dependences of threshold energies, the computer simulations have been performed using the ACAT code. It is found that in the near-threshold regime the angular dependences of sputtering yield by heavy ions are much different from those by light ions.

  20. Influence of gas flow and applied voltage on interaction of jets in a cross-field helium plasma jet array

    NASA Astrophysics Data System (ADS)

    Wan, Meng; Liu, Feng; Fang, Zhi; Zhang, Bo; Wan, Hui

    2017-09-01

    Atmospheric Pressure Plasma Jet arrays can greatly enhance the treatment area to fulfill the need for large-scale surface processing, while the spatial uniformity of the plasma jet array is closely related to the interactions of the adjacent jets. In this paper, a three-tube one-dimensional (1D) He plasma jet array with a cross-field needle-ring electrode structure is used to investigate the influences of the gas flow rate and applied voltage on the interactions of the adjacent jets through electrical, optical, and fluid measurements. The repulsion of the adjacent plume channels is observed using an intensified charge-coupled device (ICCD) and the influence of the gas flow rate and applied voltage on the electrostatic repulsion force, Coulomb force, is discussed. It is found that electrical coupling, mainly electrostatic repulsion force, exists among the jets in the array, which causes both the divergence of the lateral plumes and the nonlinear changes of the discharge power and the transport charge. The deflection angle of the lateral plumes with respect to the central plume in the optical images increases with the increase of applied voltage and decreases with the increase of gas flow rate. The deflection angle of the lateral plumes in the optical images is obviously larger than that of the lateral gas streams in the Schlieren images under the same experimental conditions, and the unconformity of the deflection angles is mainly attributed to the electrostatic repulsion force in adjacent plasma plume channels. The experimental results can help understand the interaction mechanisms of jets in the array and design controllable and scalable plasma jet arrays.

  1. Developing high-transmittance heterojunction diodes based on NiO/TZO bilayer thin films

    PubMed Central

    2013-01-01

    In this study, radio frequency magnetron sputtering was used to deposit nickel oxide thin films (NiO, deposition power of 100 W) and titanium-doped zinc oxide thin films (TZO, varying deposition powers) on glass substrates to form p(NiO)-n(TZO) heterojunction diodes with high transmittance. The structural, optical, and electrical properties of the TZO and NiO thin films and NiO/TZO heterojunction devices were investigated with scanning electron microscopy, X-ray diffraction (XRD) patterns, UV-visible spectroscopy, Hall effect analysis, and current-voltage (I-V) analysis. XRD analysis showed that only the (111) diffraction peak of NiO and the (002) and (004) diffraction peaks of TZO were observable in the NiO/TZO heterojunction devices, indicating that the TZO thin films showed a good c-axis orientation perpendicular to the glass substrates. When the sputtering deposition power for the TZO thin films was 100, 125, and 150 W, the I-V characteristics confirmed that a p-n junction characteristic was successfully formed in the NiO/TZO heterojunction devices. We show that the NiO/TZO heterojunction diode was dominated by the space-charge limited current theory. PMID:23634999

  2. Impurity-free quantum well intermixing for large optical cavity high-power laser diode structures

    NASA Astrophysics Data System (ADS)

    Kahraman, Abdullah; Gür, Emre; Aydınlı, Atilla

    2016-08-01

    We report on the correlation of atomic concentration profiles of diffusing species with the blueshift of the quantum well luminescence from both as-grown and impurity free quantum wells intermixed on actual large optical cavity high power laser diode structures. Because it is critical to suppress catastrophic optical mirror damage, sputtered SiO2 and thermally evaporated SrF2 were used both to enhance and suppress quantum well intermixing, respectively, in these (Al)GaAs large optical cavity structures. A luminescence blueshift of 55 nm (130 meV) was obtained for samples with 400 nm thick sputtered SiO2. These layers were used to generate point defects by annealing the samples at 950 °C for 3 min. The ensuing Ga diffusion observed as a shifting front towards the surface at the interface of the GaAs cap and AlGaAs cladding, as well as Al diffusion into the GaAs cap layer, correlates well with the observed luminescence blue shift, as determined by x-ray photoelectron spectroscopy. Although this technique is well-known, the correlation between the photoluminescence peak blue shift and diffusion of Ga and Al during impurity free quantum well intermixing on actual large optical cavity laser diode structures was demonstrated with both x ray photoelectron and photoluminescence spectroscopy, for the first time.

  3. Trace Detection with Diode Lasers

    NASA Astrophysics Data System (ADS)

    Fox, Richard W.

    1995-01-01

    Diode lasers were used to detect trace quantities of calcium, lead, chromium, cesium and rubidium. Extended -cavities were often employed for wavelength tuning and linewidth narrowing, and design considerations for the cavities are discussed. Calcium was detected under low pressure, Doppler-free conditions, and consequently the frequency stability of the laser's power spectrum was studied. The laser's frequency noise spectral density was measured and converted by calculation to the power spectrum. Examples of laser frequency noise densities with corresponding calculated power spectrums for free-running and frequency-locked conditions are given. An electronic feedback system to narrow a 657 nm wavelength diode laser's linewidth was constructed, and the resulting linewidth with respect to the locking cavity was measured to be approximately 500 Hz. Calcium atom concentrations of 0.35 x 10E-09 in water samples were measured by flame laser-enhanced ionization using a 423 nm wavelength frequency-doubled diode laser system. Analysis of the ionization signal and the noise was performed. Additional measurements of water samples with diode lasers demonstrated chromium detection at 25 x 10E-09, cesium at 0.25 x 10E -09, and rubidium at 0.25 x 10E-09. Lead was detected using a frequency-doubled diode system at a wavelength of 405 nm. The detection was by absorption from a metastable energy level; lead atoms in an argon vapor were excited into the metastable level by a radio-frequency discharge.

  4. Diode laser array

    NASA Technical Reports Server (NTRS)

    Carlson, Nils W. (Inventor); Evans, Gary A. (Inventor); Kaiser, Charlie J. (Inventor)

    1990-01-01

    A diode laser array comprises a substrate of a semiconductor material having first and second opposed surfaces. On the first surface is a plurality of spaced gain sections and a separate distributed Bragg reflector passive waveguide at each end of each gain section and optically connecting the gain sections. Each gain section includes a cavity therein wherein charge carriers are generated and recombine to generate light which is confined in the cavity. Also, the cavity, which is preferably a quantum well cavity, provides both a high differential gain and potentially large depth of loss modulation. Each waveguide has a wavelength which is preferably formed by an extension of the cavity of the gain sections and a grating. The grating has a period which provides a selective feedback of light into the gain sections to supporting lasing, which allows some of the light to be emitted from the waveguide normal to the surface of the substrate and which allows optical coupling of the gain sections. Also, the grating period provides an operating wavelength which is on the short wavelength side of the gain period of the gain sections required for laser oscillation. An RF pulse is applied so as to maximize the magnitude of the loss modulation and the differential gain in the gain sections. The array is operated by applying a DC bias to all the gain sections at a level just below the threshold of the gain sections to only one of the gain sections which raises the bias in all of the gain sections to a level that causes all of the gain sections to oscillate. Thus, a small bias can turn the array on and off.

  5. A Heterodyne Interferometer For Testing Laser Diodes

    NASA Astrophysics Data System (ADS)

    1983-11-01

    A heterodyne, Mach-Zehnder interferometer system has been developed for testing the wavefront quality of laser diode collimator pens. The testing system is described and the problems associated with testing laser diodes are discussed.

  6. Mounting for diodes provides efficient heat sink

    NASA Technical Reports Server (NTRS)

    1964-01-01

    Efficient heat sink is provided by soldering diodes to metal support bars which are brazed to a ceramic base. Electrical connections between diodes on adjacent bars are made flexible by metal strips which aid in heat dissipation.

  7. Transport Phenomena of Off-Axis Sputtering Deposition

    NASA Technical Reports Server (NTRS)

    Zhu, S.; Su, C.; Lehoczky, S. L.; Rose, M. Franklin (Technical Monitor)

    2001-01-01

    Various high quality epitaxial films, especially oxides, have been synthesized using off-axis sputtering deposition. In this presentation, we report the experiment results of ZnO films grown by the off-axis sputtering deposition. Films were synthesized in temperatures ranged from room temperature to 600 C, and pressures from 5 mTorr to 150 mTorr. Film growth rate was measured by surface profilometer, ellipsometer, and wavelength dispersive spectrometry. Due to the collisions between the sputtered species and the residue gases, the kinetic energy of species was reduced and the transport of depositing species changed from a ballistic movement for low pressure to a diffusive drift for high pressure in which the transport species were almost thermalized. The measurements show an increase of growth rates along the gravity vector when the Knudsen number of transport species is less than 0.05, which suggests that gravity affected the transport characterization in off-axis sputtering deposition. Because the product of pressure (p) and travel distance (d) of sputtered species, pd, exceeds several mTorr-cm during film deposition, the classical simulations for sputtering process in high vacuum system may not be applied. Based on these experimental measurements, a transport process of the off-axis sputtering deposition is proposed. Several models including the Monte Carlo method and gravity-driven flow dynamics simulation will be discussed.

  8. Transport Phenomena of Off-Axis Sputtering Deposition

    NASA Technical Reports Server (NTRS)

    Zhu, S.; Su, C. H.; Lehoczky, S. L.; Zhang, S.; Whitaker, Ann F. (Technical Monitor)

    2001-01-01

    Various high quality epitaxial films, especially oxides, have been synthesized using off-axis sputtering deposition. In this presentation, we report the experiment results of ZnO films grown by the off-axis sputtering deposition. Films were synthesized in temperatures ranged from room temperature to 600 C, and pressures from 5 mTorr to 150 mTorr. Film growth rate was measured by surface profilometer, ellipsometer, and wavelength dispersive spectrometry. Due to the collisions between the sputtered species and the residue gases, the kinetic energy of species was reduced and the transport of depositing species changed from a ballistic movement for low pressure to a diffuse drift for high pressure in which the transport species were almost thermalized. The measurements show an increase of growth rates along the gravity vector when the Knodson (Knudsen??) number of transport species is less than 0.05, which suggests that gravity affected the transport characterization in off-axis sputtering deposition. Because the product of pressure (p) and travel distance (d) of sputtered species, p exceeds several mTorr-cm during film deposition, the classical simulations for sputtering process in high vacuum system may not be applied. Based on these experimental measurements, a transport process of the off-axis sputtering deposition is proposed. Several methods including the Monte Carlo method and gravity-driven flow dynamics simulation will be discussed.

  9. Transport Phenomena of Off-Axis Sputtering Deposition

    NASA Technical Reports Server (NTRS)

    Zhu, S.; Su, C. H.; Lehoczky, S. L.; Zhang, S.; Whitaker, Ann F. (Technical Monitor)

    2001-01-01

    Various high quality epitaxial films, especially oxides, have been synthesized using off-axis sputtering deposition. In this presentation, we report the experiment results of ZnO films grown by the off-axis sputtering deposition. Films were synthesized in temperatures ranged from room temperature to 600 C, and pressures from 5 mTorr to 150 mTorr. Film growth rate was measured by surface profilometer, ellipsometer, and wavelength dispersive spectrometry. Due to the collisions between the sputtered species and the residue gases, the kinetic energy of species was reduced and the transport of depositing species changed from a ballistic movement for low pressure to a diffuse drift for high pressure in which the transport species were almost thermalized. The measurements show an increase of growth rates along the gravity vector when the Knodson (Knudsen??) number of transport species is less than 0.05, which suggests that gravity affected the transport characterization in off-axis sputtering deposition. Because the product of pressure (p) and travel distance (d) of sputtered species, p exceeds several mTorr-cm during film deposition, the classical simulations for sputtering process in high vacuum system may not be applied. Based on these experimental measurements, a transport process of the off-axis sputtering deposition is proposed. Several methods including the Monte Carlo method and gravity-driven flow dynamics simulation will be discussed.

  10. Transport Phenomena of Off-Axis Sputtering Deposition

    NASA Technical Reports Server (NTRS)

    Zhu, S.; Su, C.; Lehoczky, S. L.; Rose, M. Franklin (Technical Monitor)

    2001-01-01

    Various high quality epitaxial films, especially oxides, have been synthesized using off-axis sputtering deposition. In this presentation, we report the experiment results of ZnO films grown by the off-axis sputtering deposition. Films were synthesized in temperatures ranged from room temperature to 600 C, and pressures from 5 mTorr to 150 mTorr. Film growth rate was measured by surface profilometer, ellipsometer, and wavelength dispersive spectrometry. Due to the collisions between the sputtered species and the residue gases, the kinetic energy of species was reduced and the transport of depositing species changed from a ballistic movement for low pressure to a diffusive drift for high pressure in which the transport species were almost thermalized. The measurements show an increase of growth rates along the gravity vector when the Knudsen number of transport species is less than 0.05, which suggests that gravity affected the transport characterization in off-axis sputtering deposition. Because the product of pressure (p) and travel distance (d) of sputtered species, pd, exceeds several mTorr-cm during film deposition, the classical simulations for sputtering process in high vacuum system may not be applied. Based on these experimental measurements, a transport process of the off-axis sputtering deposition is proposed. Several models including the Monte Carlo method and gravity-driven flow dynamics simulation will be discussed.

  11. 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.

  12. Comparison of the sputter rates of oxide films relative to the sputter rate of SiO{sub 2}

    SciTech Connect

    Baer, D. R.; Engelhard, M. H.; Lea, A. S.; Nachimuthu, P.; Droubay, T. C.; Kim, J.; Lee, B.; Mathews, C.; Opila, R. L.; Saraf, L. V.; Stickle, W. F.; Wallace, R. M.; Wright, B. S.

    2010-09-15

    There is a growing interest in knowing the sputter rates for a wide variety of oxides because of their increasing technological importance in many different applications. To support the needs of users of the Environmental Molecular Sciences Laboratory, a national scientific user facility, as well as our research programs, the authors made a series of measurements of the sputter rates from oxide films that have been grown by oxygen plasma-assisted molecular beam epitaxy, pulsed laser deposition, atomic layer deposition, electrochemical oxidation, or sputter deposition. The sputter rates for these oxide films were determined in comparison with those from thermally grown SiO{sub 2}, a common reference material for sputter rate determination. The film thicknesses and densities for most of these oxide films were measured using x-ray reflectivity. These oxide films were mounted in an x-ray photoelectron or Auger electron spectrometer for sputter rate measurements using argon ion sputtering. Although the primary objective of this work was to determine relative sputter rates at a fixed angle, the measurements also examined (i) the angle dependence of the relative sputter rates, (ii) the energy dependence of the relative sputter rates, and (iii) the extent of ion beam induced reduction for some oxides. Oxide films examined include SiO{sub 2}, Al{sub 2}O{sub 3}, CeO{sub 2}, Cr{sub 2}O{sub 3}, Fe{sub 2}O{sub 3}, HfO{sub 2}, In-Sn oxide, Ta{sub 2}O{sub 5}, TiO{sub 2} (anatase, rutile, and amorphous), and ZnO. The authors found that the sputter rates for the oxides can vary up to a factor of 2 (usually lower) from that observed for SiO{sub 2}. The ratios of sputter rates relative to those of SiO{sub 2} appear to be relatively independent of ion beam energy in the range of 1-4 kV and for incident angles <50 deg. As expected, the extent of ion beam induced reduction of the oxides varies with the sputter angle.

  13. Post Magnetron Sputter And Reactive Sputter Coating Of Contoured Glass, Acrylic And Polycarbonate Substrates

    NASA Astrophysics Data System (ADS)

    Wright, Michael P.

    1985-12-01

    A Post Magnetron Sputter concept employing a cylindrical internally cooled target (cathode) is described. The use of an internal, rotating, permanent magnetic field resulting in 360° utilisation of the target material is outlined. Computer controlled horizontal and vertical movement of the cathode assembly facilitates the coating of contoured substrates which may be glass, acrylic or polycarbonate. Deposition of different metals is easily achieved by changing the cathode or covering it with a suitable sheath material. The design of the cathode results in economic utilisation of the target material, which is particularly important when sputtering expensive metals such as gold. In addition to the deposition of metallic films, such as stainless steel or chrome, reactive sputtering may be undertaken by the introduction of a reactive gas into the vacuum chamber. In this way metal oxide, sulphide or nitride layers may be deposited according to the requirements of the layer structure. Specific optically-active oxides such as indium tin oxide are easily deposited in a uniform film and the formation of multilayer coatings for sun protective and heat rejecting applications is practicable. Indeed, a complete process may be undertaken without removing the substrate from the chamber; merely by adding or changing the reactive gas present.

  14. Evolution of sputtering target surface composition in reactive high power impulse magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Kubart, T.; Aijaz, A.

    2017-05-01

    The interaction between pulsed plasmas and surfaces undergoing chemical changes complicates physics of reactive High Power Impulse Magnetron Sputtering (HiPIMS). In this study, we determine the dynamics of formation and removal of a compound on a titanium surface from the evolution of discharge characteristics in an argon atmosphere with nitrogen and oxygen. We show that the time response of a reactive process is dominated by surface processes. The thickness of the compound layer is several nm and its removal by sputtering requires ion fluence in the order of 1016 cm-2, much larger than the ion fluence in a single HiPIMS pulse. Formation of the nitride or oxide layer is significantly slower in HiPIMS than in dc sputtering under identical conditions. Further, we explain very high discharge currents in HiPIMS by the formation of a truly stoichiometric compound during the discharge off-time. The compound has a very high secondary electron emission coefficient and leads to a large increase in the discharge current upon target poisoning.

  15. Neutron Radiation Induced Degradation of Diode Characteristics,

    DTIC Science & Technology

    1992-12-01

    3). La plupart des r6sultats anterieurs sur les diodes A jonction p-n correspondent aux r~sultats des diodes du type 1. Les diodes du type 2 sont...d’autres types de diodes non reportds plus t6t. Ces rt~sultats sont expliqu~s qualitativement-en termes des th6ories pour une jonction p-n et pour les

  16. Potential energy sputtering of EUVL materials

    SciTech Connect

    Pomeroy, J M; Ratliff, L P; Gillaspy, J D; Bajt, S

    2004-07-02

    Of the many candidates employed for understanding the erosion of critical Extreme Ultraviolet Lithography (EUVL) components, potential energy damage remains relatively uninvestigated. Unlike the familiar kinetic energy sputtering, which is a consequence of the momentum transferred by an ion to atoms in the target, potential energy sputtering occurs when an ion rapidly collects charge from the target as it neutralizes. Since the neutralization energy of a singly charged ion is typically on the order of 10 eV, potential energy effects are generally neglected for low charge state ions, and hence the bulk of the sputtering literature. As an ion's charge state is increased, the potential energy (PE) increases rapidly, e.g. PE(Xe{sup 1+})= 11 eV, PE(Xe{sup 10+}) = 810 eV, PE(Xe{sup 20+}) = 4.6 keV, etc. By comparison, the binding energy of a single atom on a surface is typically about 5 eV, so even relatively inefficient energy transfer mechanisms can lead to large quantities of material being removed, e.g. 25% efficiency for Xe{sup 10+} corresponds to {approx} 40 atoms/ion. By comparison, singly charged xenon ions with {approx} 20 keV of kinetic energy sputter only about 5 atoms/ion at normal incidence, and less than 1 atom/ion at typical EUV source energies. EUV light sources are optimized for producing approximately 10{sup 16} xenon ions per shot with an average charge state of q=10 in the core plasma. At operational rates of {approx}10 kHz, the number of ions produced per second becomes a whopping 10{sup 20}. Even if only one in a billion ions reaches the collector, erosion rates could reach {approx}10{sup 12} atoms per second, severely reducing the collector lifetime (for an average yield of 10 atoms/ion). In addition, efforts to reduce contamination effects may contribute to reduced neutralization and even larger potential energy damages rates (discussed further below). In order to provide accurate estimates for collector lifetimes and to develop mitigation schemes

  17. Simulation of sputter deposition in dc magnetrons

    NASA Astrophysics Data System (ADS)

    Evstatiev, Evstati; Cluggish, Brian

    2010-11-01

    Material sputter deposition has a multitude of industrial applications. Our goal at FAR-TECH, Inc., is a complete numerical simulation of a dc magnetron device. We intend to modify existing FAR-TECH, Inc. code to include flexible geometry manipulation, the most current atomic physics data, add transport of neutral atoms across the device, and model deposition on the substrate. Currently, dc magnetron simulation codes have limited geometry manipulation capabilities; however, this is important if design optimization is intended. Another uncommon feature in dc magnetron simulation codes is parallel performance. Since PIC simulations may take extremely long times (weeks), we are parallelizing our codes to achieve shorter run times. (Codes based on hybrid models perform faster, but have the disadvantage of having to know accurately the diffusion coefficients of electrons across the magnetic field lines.) We report preliminary results of this effort.

  18. Sputtered protective coatings for die casting dies

    NASA Technical Reports Server (NTRS)

    Mirtich, M. J.; Nieh, C.-Y.; Wallace, J. F.

    1981-01-01

    Three experimental research designs investigating candidate materials and processes involved in protective die surface coating procedures by sputter deposition, using ion beam technologies, are discussed. Various pre-test results show that none of the coatings remained completely intact for 15,000 test cycles. The longest lifetime was observed for coatings such as tungsten, platinum, and molybdenum which reduced thermal fatigue, but exhibited oxidation and suppressed crack initiation only as long as the coating did not fracture. Final test results confirmed earlier findings and coatings with Pt and W proved to be the candidate materials to be used on a die surface to increase die life. In the W-coated specimens, which remained intact on the surface after thermal fatigue testing, no oxidation was found under the coating, although a few cracks formed on the surface where the coating broke down. Further research is planned.

  19. Ion Beam Sputtered Coatings of Bioglass

    NASA Technical Reports Server (NTRS)

    Hench, Larry L.; Wilson, J.; Ruzakowski, Patricia Henrietta Anne

    1982-01-01

    The ion beam sputtering technique available at the NASA-Lewis was used to apply coatings of bioglass to ceramic, metallic, and polymeric substrates. Experiments in vivo and in vitro described investigate these coatings. Some degree of substrate masking was obtained in all samples although stability and reactivity equivalent to bulk bioglass was not observed in all coated samples. Some degree of stability was seen in all coated samples that were reacted in vitro. Both metallic and ceramic substrates coated in this manner failed to show significantly improved coatings over those obtained with existing techniques. Implantation of the coated ceramic substrate samples in bone gave no definite bonding as seen with bulk glass; however, partial and patchy bonding was seen. Polymeric substrates in these studies showed promise of success. The coatings applied were sufficient to mask the underlying reactive test surface and tissue adhesion of collagen to bioglass was seen. Hydrophilic, hydrophobic, charged, and uncharged polymeric surfaces were successfully coated.

  20. Sputtered protective coatings for die casting dies

    NASA Technical Reports Server (NTRS)

    Mirtich, M. J.; Nieh, C.-Y.; Wallace, J. F.

    1981-01-01

    Three experimental research designs investigating candidate materials and processes involved in protective die surface coating procedures by sputter deposition, using ion beam technologies, are discussed. Various pre-test results show that none of the coatings remained completely intact for 15,000 test cycles. The longest lifetime was observed for coatings such as tungsten, platinum, and molybdenum which reduced thermal fatigue, but exhibited oxidation and suppressed crack initiation only as long as the coating did not fracture. Final test results confirmed earlier findings and coatings with Pt and W proved to be the candidate materials to be used on a die surface to increase die life. In the W-coated specimens, which remained intact on the surface after thermal fatigue testing, no oxidation was found under the coating, although a few cracks formed on the surface where the coating broke down. Further research is planned.

  1. Plasma Induced Sputtered Exosphere of Callisto

    NASA Astrophysics Data System (ADS)

    Pfleger, Martin; Lammer, Helmut; Lindkvist, Jesper; Holmström, Mats; Vorburger, Audrey; Galli, André; Wurz, Peter; Lichtenegger, Herbert; Barabash, Stas

    2014-05-01

    A better understanding of particle release processes from the Gallilean satellites such as Callisto's surface is needed for planned exospheric and remote surface geochemical studies by the particle and plasma instruments of the PEP experiment on board of ESA's JUICE mission. We study the interaction between the Jovian magnetosphere plasma and Callisto's surface with a hybrid model and applied a geochemical surface composition model for the input of the surface sputter release. Then we apply a 3-D exospheric model for studying the feasibility of exospheric measurements. We model energy and ejection angle distributions of the released particles from the surface, with the emission process determining the actual distribution functions. Our model follows the trajectory of each particle by numerical integration until the particle hits Callisto's surface again or escapes from the calculation domain. Using a large set of these trajectories, bulk parameters of the exospheric gas are derived, e.g., particle densities for various species.

  2. 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.

  3. Method of making diode structures

    DOEpatents

    Compaan, Alvin D.; Gupta, Akhlesh

    2006-11-28

    A method of making a diode structure includes the step of depositing a transparent electrode layer of any one or more of the group ZnO, ZnS and CdO onto a substrate layer, and depositing an active semiconductor junction having an n-type layer and a p-type layer onto the transparent electrode layer under process conditions that avoid substantial degradation of the electrode layer. A back electrode coating layer is applied to form a diode structure.

  4. Calibrated feedback for laser diodes

    SciTech Connect

    Howard, P.G.

    1986-04-22

    A method is described of calibrating the feedback output from the feedback light detector of the laser diode of an optical disk drive of a laser light pen which consists of mounting a first and a second resistor in a laser light pen; connecting the first resistor between the feedback light detector and ground; connecting the second resistor between the feedback light detector and a feedback output; operating the laser diode to produce a predetermined light power output; adjusting the resistance of the first resistor to produce a predetermined voltage at the feedback output; and adjusting the resistance of the second resistor to produce a predetermined impedance at the feedback output.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. Mass fractionation of the lunar surface by solar wind sputtering

    NASA Technical Reports Server (NTRS)

    Switkowski, Z. E.; Haff, P. K.; Tombrello, T. A.; Burnett, D. S.

    1977-01-01

    An investigation is conducted concerning the mass-fractionation effects produced in connection with the bombardment of the moon by the solar wind. Most of the material ejected by sputtering escapes the moon's gravity, but some returning matter settles back onto the lunar surface. This material, which is somewhat richer in heavier atoms than the starting surface, is incorporated into the heavily radiation-damaged outer surfaces of grains. The investigation indicates that sputtering of the lunar surface by the solar wind will give rise to significant surface heavy atom enrichments if the grain surfaces are allowed to come into sputtering equilibrium.

  10. 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.

  11. Porous, High Capacity Coatings for Solid Phase Microextraction by Sputtering.

    PubMed

    Diwan, Anubhav; Singh, Bhupinder; Roychowdhury, Tuhin; Yan, DanDan; Tedone, Laura; Nesterenko, Pavel N; Paull, Brett; Sevy, Eric T; Shellie, Robert A; Kaykhaii, Massoud; Linford, Matthew R

    2016-02-02

    We describe a new process for preparing porous solid phase microextraction (SPME) coatings by the sputtering of silicon onto silica fibers. The microstructure of these coatings is a function of the substrate geometry and mean free path of the silicon atoms, and the coating thickness is controlled by the sputtering time. Sputtered silicon structures on silica fibers were treated with piranha solution (a mixture of concd H2SO4 and 30% H2O2) to increase the concentration of silanol groups on their surfaces, and the nanostructures were silanized with octadecyldimethylmethoxysilane in the gas phase. The attachment of this hydrophobic ligand was confirmed by X-ray photoelectron spectroscopy and contact angle goniometry on model, planar silicon substrates. Sputtered silicon coatings adhered strongly to their surfaces, as they were able to pass the Scotch tape adhesion test. The extraction time and temperature for headspace extraction of mixtures of alkanes and alcohols on the sputtered fibers were optimized (5 min and 40 °C), and the extraction performances of SPME fibers with 1.0 or 2.0 μm of sputtered silicon were compared to those from a commercial 7 μm poly(dimethylsiloxane) (PDMS) fiber. For mixtures of alcohols, aldehydes, amines, and esters, the 2.0 μm sputtered silicon fiber yielded signals that were 3-9, 3-5, 2.5-4.5, and 1.5-2 times higher, respectively, than those of the commercial fiber. For the heavier alkanes (undecane-hexadecane), the 2.0 μm sputtered fiber yielded signals that were approximately 1.0-1.5 times higher than the commercial fiber. The sputtered fibers extracted low molecular weight analytes that were not detectable with the commercial fiber. The selectivity of the sputtered fibers appears to favor analytes that have both a hydrophobic component and hydrogen-bonding capabilities. No detectable carryover between runs was noted for the sputtered fibers. The repeatability (RSD%) for a fiber (n = 3) was less than 10% for all analytes tested

  12. Development of latent fingerprints using preferential DC sputter deposition.

    PubMed

    Kent, K; Stoilovic, M

    1995-03-21

    It was shown that a DC metal sputtering process with thermalised atoms, preferentially deposits metal onto fingerprint ridges. This method can be successfully used for the development of latent fingerprints. Four target metals were tested--copper, zinc, platinum, and gold--with platinum showing superior results for latent fingerprint development on clear polythene substrates. A comparison of platinum sputtering and cyanoacrylate fuming followed by rhodamine-6G staining, was conducted for 1-year-old fingerprint deposits. Platinum sputtering showed significantly higher sensitivity, and produced better overall results.

  13. Modeling of iron oxide deposition by reactive ion beam sputtering

    SciTech Connect

    Puech, Laurent; Dubarry, Christophe; Ravel, Guillaume; Vito, Eric de

    2010-03-15

    An analytic model of deposition is applied on reactive ion beam sputtering to optimize the properties of iron oxide thin films. This model will be able to predict deposition rate and phase contents. Among its hypotheses, we assume oxygen adsorption at the surface of the target to explain variations of deposition rate for oxygen flow. This hypothesis is validated by chemical analyses on iron targets. An ellipsoidal distribution of probability is introduced to model sputtered matter distribution from iron target and to calculate sputtering yield. Comparison between experimental and calculated deposition rates validates previously assumed hypotheses.

  14. The new applications of sputtering and ion plating

    NASA Technical Reports Server (NTRS)

    Spalvins, T.

    1977-01-01

    The potential industrial applications of sputtering and ion plating are strictly governed by the unique features these methods possess. The outstanding features of each method, the resultant coating characteristics and the various sputtering modes and configurations are discussed. New, more complex coatings and deposits can be developed such as graded composition structures (metal-ceramic seals), laminated and dispersion strengthened composites which improve the mechanical properties and high temperature stability. Specific industrial areas where future effort of sputtering and ion plating will concentrate to develop intricate alloy or compound coatings and solve difficult problem areas are discussed.

  15. Whiskers, cones and pyramids created in sputtering by ion bombardment

    NASA Technical Reports Server (NTRS)

    Wehner, G. K.

    1979-01-01

    A thorough study of the role which foreign atoms play in cone formation during sputtering of metals revealed many experimental facts. Two types of cone formation were distinquished, deposit cones and seed cones. Twenty-six combinations of metals for seed cone formation were tested. The sputtering yield variations with composition for combinations which form seed cones were measured. It was demonstrated that whisker growth becomes a common occurrence when low melting point material is sputter deposited on a hot nonsputtered high melting point electrode.

  16. Low Temperature Thermometry Using Inexpensive Silicon Diodes.

    ERIC Educational Resources Information Center

    Waltham, N. R.; And Others

    1981-01-01

    Describes the use of silicon diodes for low temperature thermometry in the teaching laboratory. A simple and inexpensive circuit for display of the diode forward voltage under constant current conditions is described, and its application in the evaluation of low cost silicon diodes as low temperature thermometers is presented. (SK)

  17. Low Temperature Thermometry Using Inexpensive Silicon Diodes.

    ERIC Educational Resources Information Center

    Waltham, N. R.; And Others

    1981-01-01

    Describes the use of silicon diodes for low temperature thermometry in the teaching laboratory. A simple and inexpensive circuit for display of the diode forward voltage under constant current conditions is described, and its application in the evaluation of low cost silicon diodes as low temperature thermometers is presented. (SK)

  18. IC Fabrication Methods Improve Laser Diodes

    NASA Technical Reports Server (NTRS)

    Miller, M.; Pickhardt, V.

    1984-01-01

    Family of high-performance, tunable diode lasers developed for use as local oscillators in passive laser heterodyne spectrometer. Diodes fabricated using standard IC processes include photolithography, selective etching and vacuum deposition of metals and insulators. Packaging refinements improved thermal-cycling characteristics of diodes and increased room-temperature shelf life.

  19. Neutron Radiation Induced Degradation of Diode Characteristics

    DTIC Science & Technology

    1992-12-01

    de fluance utilis6 dans ce travail (diode du type 3). La plupart des r~sultats anterieurs sur les, diodes A jonction p-n correspondent aux rdsultats...termes des thories pour une jonction p-n et pour les effects de radiations sur semiconducteurs. II est prddit qu’une diode du type 3 pourrait &tre

  20. Preparation and characteristics of vanadium oxide thin films by controlling the sputtering voltage

    NASA Astrophysics Data System (ADS)

    Wei, Xiongbang; Li, Shibin; Gou, Jun; Dong, Xiang; Yang, Xiaohui; Li, Weizhi; Wang, Tao; Wu, Zhiming; Jiang, Yadong; Chen, Zhi

    2014-06-01

    Influence of sputtering voltage on the deposition process and characteristics of vanadium oxide thin films prepared by reactive DC magnetron sputtering is investigated. The target surface cleaning is controlled by adjusting the sputtering voltage. During the sputtering process, the sputtering voltage increases faster with larger O2 gas flow rate. The sputtering voltage is easy to be stable with larger sputtering voltage. The measured sputtering voltage is correlated to the ion induced secondary electron emission (ISEE) coefficient of the target material. The ISEE coefficient of the oxidized vanadium target surface is lower than the ISEE coefficient of the vanadium metal. The semiconductor to metal (S-M) phase transition temperature decreases with the sputtering voltage, leading to the lower the corresponding temperature of the maximum temperature coefficient of resistance (TCR). By this way, O/V ratio, R, and TCR of VOx films can be controlled by adjusting the sputtering voltage.

  1. Self-sputtering runaway in high power impulse magnetron sputtering: The role of secondary electrons and multiply charged metal ions

    SciTech Connect

    Anders, Andre

    2008-05-19

    Self-sputtering runaway in high power impulse magnetron sputtering is closely related to the appearance of multiply charged ions. This conclusion is based on the properties of potential emission of secondary electrons and energy balance considerations. The effect is especially strong for materials whose sputtering yield is marginally greater than unity. The absolute deposition rate increases {approx}Q{sup 1/2}, whereas the rate normalized to the average power decreases {approx}Q{sup -1/2}, with Q being the mean ion charge state number.

  2. Characteristic diode parameters in thermally annealed Ni/p-InP contacts

    NASA Astrophysics Data System (ADS)

    Turut, A.; Ejderha, K.; Yildirim, N.; Abay, B.

    2016-04-01

    The Ni/p-InP Schottky diodes (SDs) have been prepared by DC magnetron sputtering deposition. After the diode fabrication, they have been thermally annealed at 700 °C for 1 min in N2 atmosphere. Then, the current-voltage characteristics of the annealed and non-annealed (as-deposited) SDs have been measured in the measurement temperature range of 60-400 K with steps of 20 K under dark conditions. After 700 °C annealing, an improvement in the ideality factor value has been observed from 60 to 200 K and the barrier height (BH) value approximately has remained unchanged in the measurement temperature range of 200-400 K. The BH of the annealed diode has decreased obeying the double-Gaussian distribution (GD) of the BHs with decreasing measurement temperature from 200 to 60 K. The BH for the as-deposited diode has decreased with decreasing temperature obeying the single-GD over the whole measurement temperature range. An effective Richardson constant value of 54.21 A/cm2K2 for the as-deposited SD has been obtained from the modified Richardson plot by the single-GD plot, which is in very close agreement with the value of 60 A/K2cm2 for p-type InP. The series resistance value of the annealed SD is lower than that of the non-annealed SD at each temperature and approximately has remained unchanged from 140 to 240 K. Thus, it can be said that an improvement in the diode parameters has been observed due to the thermal annealing at 700 °C for 1 min in N2 atmosphere.

  3. Harmonic Power Generation of IMPATT Diodes.

    DTIC Science & Technology

    1985-09-01

    computer simulation program for IMPATT diodes, employing the drift- diffusion model, is used to investigate four different conventional double-drift IMPATT...Present Study 21 CHAPTER II. LARGE- SIGNAL SIMULATION OF Si AND GaAs IMPATT DIODES 23 2.1 Introduction 23 2.2 Description of Computer Simulation Program...Design Considerations for pin Diodes 145 2.4.4 Brief Description of Small- Signal Analysis for pin Diodes 147 2.4.5 Performance of pin Diodes in Single

  4. Development of RF sputtered chromium oxide coating for wear application

    NASA Technical Reports Server (NTRS)

    Bhushan, B.

    1979-01-01

    The radio frequency sputtering technique was used to deposite a hard refractory, chromium oxide coating on an Inconel X-750 foil 0.1 mm thick. Optimized sputtering parameters for a smooth and adherent coating were found to be as follows: target-to-substrate spacing, 41.3 mm; argon pressure, 5-10 mTorr; total power to the sputtering module, 400 W (voltage at the target, 1600 V), and a water-cooled substrate. The coating on the annealed foil was more adherent than that on the heat-treated foil. Substrate biasing during the sputter deposition of Cr2O3 adversely affected adherence by removing naturally occurring interfacial oxide layers. The deposited coatings were amorphous and oxygen deficient. Since amorphous materials are extremely hard, the structure was considered to be desirable.

  5. RF Sputtering for preparing substantially pure amorphous silicon monohydride

    DOEpatents

    Jeffrey, Frank R.; Shanks, Howard R.

    1982-10-12

    A process for controlling the dihydride and monohydride bond densities in hydrogenated amorphous silicon produced by reactive rf sputtering of an amorphous silicon target. There is provided a chamber with an amorphous silicon target and a substrate therein with the substrate and the target positioned such that when rf power is applied to the target the substrate is in contact with the sputtering plasma produced thereby. Hydrogen and argon are fed to the chamber and the pressure is reduced in the chamber to a value sufficient to maintain a sputtering plasma therein, and then rf power is applied to the silicon target to provide a power density in the range of from about 7 watts per square inch to about 22 watts per square inch to sputter an amorphous silicon hydride onto the substrate, the dihydride bond density decreasing with an increase in the rf power density. Substantially pure monohydride films may be produced.

  6. Sputter deposition of metallic thin film and directpatterning

    SciTech Connect

    Ji, L.; Chen, Y.; Jiang, X.; Ji, Q.; Leung, K.-N.

    2005-09-09

    A compact apparatus is developed for deposition of metal thin film. The system employs an RF discharge plasma source with a straight RF antenna, which is made of or covered with deposition material, serving as sputtering target at the same time. The average deposition rate of copper thin film is as high as 450nm/min. By properly allocating the metal materials on the sputtering antenna, mixture deposition of multiple metal species is achieved. Using an ion beam imprinting scheme also taking advantage of ion beam focusing technique, two different schemes of direct patterning deposition process are developed: direct depositing patterned metallic thin film and resistless ion beam sputter patterning. Preliminary experiments have demonstrated direct pattern transfer from a template with feature size of micro scale; patterns with more than 10x reduction are achieved by sputtering patterning method.

  7. Sputtering of Au induced by single Xe ion impacts

    SciTech Connect

    Birtcher, R. C.; Donnelly, S. E.

    1999-12-06

    Sputtering of Au thin films has been determined for Xe ions with energies between 50 and 600 keV. In-situ transmission electron microscopy was used to observe sputtered Au during deposition on a carbon foil near the specimen. Total reflection and transmission sputtering yields for a 62 nm thick Au thin film were determined by ex-situ measurement of the total amount of Au on the carbon foils. In situ observations show that individual Xe ions eject Au nanoparticles as large as 7 nm in diameter with an average diameter of approximately 3 nm. Particle emission correlates with crater formation due to single ion impacts. Nanoparticle emission contributes significantly to the total sputtering yield for Xe ions in this energy range in either reflection or transmission geometry.

  8. Nanopatterning of swinging substrates by ion-beam sputtering

    NASA Astrophysics Data System (ADS)

    Yoon, Sun Mi; Kim, J.-S.

    2016-05-01

    Graphite substrates are azimuthally swung during ion-beam sputtering (IBS) at a polar angle θ = 78° from the surface normal. The swinging of the substrate not only causes quasi-two-dimensional mass transport but also makes various sputter effects from the different incident angles to work together. Through variation of the swing angle, both the transport and sputtering effects synergistically produce a series of salient patterns, such as asymmetric wall-like structures, which can grow to several tens of nanometers and exhibit a re-entrant orientational change with the increased swing angle. Thus, the present work demonstrates that dynamic variables such as the swing angle, which have been little utilized, offer an additional parameter space that can be exploited to diversify the sputtered patterns, thereby expanding the applicability of an IBS as well as the comprehension of the IBS nano patterning mechanism.

  9. The corrosivity and passivity of sputtered Mg-Ti alloys

    DOE PAGES

    Song, Guang -Ling; Unocic, Kinga A.; Meyer, III, Harry M.; ...

    2015-11-30

    Our study explored the possibility of forming a “stainless” Mg–Ti alloy. The electrochemical behavior of magnetron-sputtered Mg–Ti alloys was measured in a NaCl solution, and the surface films on the alloys were examined by XPS, SEM and TEM. Increased corrosion resistance was observed with increased Ti content in the sputtered Mg–Ti alloys, but passive-like behavior was not reached until the Ti level (atomic %) was higher than the Mg level. Moreover, the surface film that formed on sputtered Mg–Ti based alloys in NaCl solution was thick, discontinuous and non-protective, whereas a thin, continuous and protective Mg and Ti oxide filmmore » was formed on a sputtered Ti–Mg based alloy.« less

  10. The corrosivity and passivity of sputtered Mg-Ti alloys

    SciTech Connect

    Song, Guang -Ling; Unocic, Kinga A.; Meyer, III, Harry M.; Cakmak, Ercan; Brady, Michael P.; Gannon, Paul E.; Himmer, Phil; Andrews, Quinn

    2015-11-30

    Our study explored the possibility of forming a “stainless” Mg–Ti alloy. The electrochemical behavior of magnetron-sputtered Mg–Ti alloys was measured in a NaCl solution, and the surface films on the alloys were examined by XPS, SEM and TEM. Increased corrosion resistance was observed with increased Ti content in the sputtered Mg–Ti alloys, but passive-like behavior was not reached until the Ti level (atomic %) was higher than the Mg level. Moreover, the surface film that formed on sputtered Mg–Ti based alloys in NaCl solution was thick, discontinuous and non-protective, whereas a thin, continuous and protective Mg and Ti oxide film was formed on a sputtered Ti–Mg based alloy.

  11. Development of hydrophobicity of mica surfaces by ion beam sputtering

    NASA Astrophysics Data System (ADS)

    Metya, Amaresh; Ghose, Debabrata; Ray, Nihar Ranjan

    2014-02-01

    The hydrophilic mica surface can be made hydrophobic by low energy Ar+ ion sputtering. The ion sputtering leads to both topographical and physicochemical changes of the surface which are thought to be responsible for the water repelling behavior. The sessile drop method is used to evaluate the wetting properties of the sputtered mica surfaces. It has been shown that the sputter-pattern at the nano-length scale has little influence on the development of hydrophobicity. On the other hand, the wettability appears to be strongly connected with the chemistry of the bombarded surface. We have also studied the temporal evolution of contact angle as the water evaporates due to difference in vapor pressures between the droplet surface and the surroundings. The analysis offers a simple method to estimate the diffusion coefficient of water vapor.

  12. Deposition of reactively ion beam sputtered silicon nitride coatings

    NASA Technical Reports Server (NTRS)

    Grill, A.

    1982-01-01

    An ion beam source was used to deposit silicon nitride films by reactively sputtering a silicon target with beams of Ar + N2 mixtures. The nitrogen fraction in the sputtering gas was 0.05 to 0.80 at a total pressure of 6 to 2 millionth torr. The ion beam current was 50 mA at 500 V. The composition of the deposited films was investigated by auger electron spectroscopy and the rate of deposition was determined by interferometry. A relatively low rate of deposition of about 2 nm. one-tenth min. was found. AES spectra of films obtained with nitrogen fractions higher than 0.50 were consistent with a silicon to nitrogen ratio corresponding to Si3N4. However the AES spectra also indicated that the sputtered silicon nitride films were contaminated with oxygen and carbon and contained significant amounts of iron, nickel, and chromium, most probably sputtered from the holder of the substrate and target.

  13. Extended incident-angle dependence formula for physical sputtering

    NASA Astrophysics Data System (ADS)

    Ono, T.; Shibata, K.; Kenmotsu, T.; Muramoto, T.; Li, Z.; Kawamura, T.

    2007-06-01

    We extend a new semi-empirical formula for incident-angle dependence of normalized sputtering yield that includes the contribution from the direct knock-out process to the sputtering yield. This was not considered fully in the previous sputtering formula. Three parameters included in the new formula are estimated for data calculated with a Monte Carlo code ACAT for D+ ions incident obliquely on C, Fe and W materials in incident energy regions from several tens of eV to 10 keV. Then, the parameters are expressed as a function of incident energy. The extended formula with these functions well reproduces the calculated data of normalized sputtering yield in the whole energy ranges.

  14. Formation of nanostructured metallic glass thin films upon sputtering.

    PubMed

    Ketov, Sergey V; Joksimovic, Rastko; Xie, Guoqiang; Trifonov, Artem; Kurihara, Kazue; Louzguine-Luzgin, Dmitri V

    2017-01-01

    Morphology evolution of the multicomponent metallic glass film obtained by radio frequency (RF) magnetron sputtering was investigated in the present work. Two modes of metallic glass sputtering were distinguished: smooth film mode and clustered film mode. The sputtering parameters, which have the most influence on the sputtering modes, were determined. As a result, amorphous Ni-Nb thin films with a smooth surface and nanoglassy structure were deposited on silica float glass and Si substrates. The phase composition of the target appeared to have a significant influence on the chemical composition of the deposited amorphous thin film. The differences in charge transport and nanomechanical properties between the smooth and nanoglassy Ni-Nb film were also determined.

  15. Thermal-Diode Sandwich Panel

    NASA Technical Reports Server (NTRS)

    Basiulis, A.

    1986-01-01

    Thermal diode sandwich panel transfers heat in one direction, but when heat load reversed, switches off and acts as thermal insulator. Proposed to control temperature in spacecraft and in supersonic missiles to protect internal electronics. In combination with conventional heat pipes, used in solar panels and other heat-sensitive systems.

  16. Structural, surface, optical, and mechanical properties of Zn3N2 thin films prepared by sputtering deposition

    NASA Astrophysics Data System (ADS)

    Wen, Ting; Jiang, Nanke; Georgiev, Daniel G.; Jayatissa, Ahalapitiya H.

    2010-04-01

    Zinc nitride and zinc oxide can have wide range applications owing to their band-gap changes and controlling capability of n-type to p-type behavior by impurity doping. Thus, zinc oxy-nitrides can be utilized to design novel photonic devices such as solar cells, UV-Visible devices, and light emitting diodes. In this paper, feasibility of tuning the optical and electronic properties of zinc oxynitride thin films in an rf magnetron sputtering deposition. It was found that the change of gas composition such as Ar: N2: O2 can change the properties of zinc nitride films for a wide range. The absorption coefficient of zinc nitride films were larger than zinc oxide thin films in low photon energy range, in particular visible region of the spectrum. These results indicated that the zinc nitride may find suitable applications in solar cells and photonic devices.

  17. Effects of sputtering power Schottky metal layers on rectifying performance of Mo-SiC Schottky contacts

    NASA Astrophysics Data System (ADS)

    Lee, Seula; Lee, Jinseon; You, Sslimsearom; Kyoung, Sinsu; Kim, Kyung Hwan

    2016-01-01

    In this study, Schottky barrier diodes based on silicon carbide with various levels of Schottky metal layer input power were prepared and characterized. In this structure, molybdenum and aluminum were employed as the Schottky metal and top electrode, respectively. Schottky metal layers were deposited with input power ranging from 30 to 210 W. Schottky metal layers and top electrodes were deposited with a thickness of 3000 Å. The Schottky barrier heights, series resistances, and ideality factor were calculated from current-voltage (I-V) curves obtained using the Cheung-Cheung and Norde methods. All deposition processes were conducted using a facing targets sputtering system. Turn on voltage was minimized when the input power was 90 W, at which point electrical characteristics were observed to have properties superior to those at other levels of input power.

  18. Magnetospheric ion sputtering and water ice grain size at Europa

    NASA Astrophysics Data System (ADS)

    Cassidy, T. A.; Paranicas, C. P.; Shirley, J. H.; Dalton, J. B., III; Teolis, B. D.; Johnson, R. E.; Kamp, L.; Hendrix, A. R.

    2013-03-01

    We present the first calculation of Europa's sputtering (ion erosion) rate as a function of position on Europa's surface. We find a global sputtering rate of 2×1027 H2O s-1, some of which leaves the surface in the form of O2 and H2. The calculated O2 production rate is 1×1026 O2 s-1, H2 production is twice that value. The total sputtering rate (including all species) peaks at the trailing hemisphere apex and decreases to about 1/3rd of the peak value at the leading hemisphere apex. O2 and H2 sputtering, by contrast, is confined almost entirely to the trailing hemisphere. Most sputtering is done by energetic sulfur ions (100s of keV to MeV), but most of the O2 and H2 production is done by cold oxygen ions (temperature ∼ 100 eV, total energy ∼ 500 eV). As a part of the sputtering rate calculation we compared experimental sputtering yields with analytic estimates. We found that the experimental data are well approximated by the expressions of Famá et al. for ions with energies less than 100 keV (Famá, M., Shi, J., Baragiola, R.A., 2008. Sputtering of ice by low-energy ions. Surf. Sci. 602, 156-161), while the expressions from Johnson et al. fit the data best at higher energies (Johnson, R.E., Burger, M.H., Cassidy, T.A., Leblanc, F., Marconi, M., Smyth, W.H., 2009. Composition and Detection of Europa's Sputter-Induced Atmosphere, in: Pappalardo, R.T., McKinnon, W.B., Khurana, K.K. (Eds.), Europa. University of Arizona Press, Tucson.). We compare the calculated sputtering rate with estimates of water ice regolith grain size as estimated from Galileo Near-Infrared Mapping Spectrometer (NIMS) data, and find that they are strongly correlated as previously suggested by Clark et al. (Clark, R.N., Fanale, F.P., Zent, A.P., 1983. Frost grain size metamorphism: Implications for remote sensing of planetary surfaces. Icarus 56, 233-245.). The mechanism responsible for the sputtering rate/grain size link is uncertain. We also report a surface composition estimate using

  19. Dust Particle Growth in a Sputtering Discharge with Krypton

    SciTech Connect

    Tawidian, H.; Mikikian, M.; Lecas, T.; Boufendi, L.

    2011-11-29

    Dust particles are grown in the PKE chamber by sputtering materials. The sputtering efficiency and the gas phase reactions can be affected by the gas type and particularly by the ion mass. Due to the presence of growing dust particles, the huge loss of electrons can trigger many instabilities in the plasma. These instabilities, the growth kinetics and the structure of the dust cloud, are compared by using two different gases: argon and krypton.

  20. Fine plastic foil as backing for sputtered nickel targets.

    PubMed

    Stolarz, Anna; Seppälä, Raimo

    Targets of (58)Ni and (60)Ni with areal density between 71 and 105 μg/cm(2) backed with polyimide foil of 35-40 μg/cm(2) were prepared by sputtering with Ar ions produced by a home made sputtering device at the Target Laboratory, University of Jyväskylä. The efficiency of the procedure was about 20 %.

  1. Theory of chemical sputtering of graphite by hydrogen

    NASA Astrophysics Data System (ADS)

    Noriaki, Itoh; Yuji, Horino

    1987-09-01

    A theory of chemical sputtering of graphite by energetic hydrogen ions has been developed. The theory is based on the physical two-step model, developed by Itoh and Hasebe to explain the synergistic effects, in which it is assumed that two potential minima exist between the initial state of reaction and the final state. It is shown that the theory can be used to explain several important features of chemical sputtering: temperature, energy and flux dependence, hysteresis, and synergistic effects.

  2. Preparation of Copper Nanoparticles in Liquid by Matrix Sputtering Process

    NASA Astrophysics Data System (ADS)

    Nakagawa, Ko; Narushima, Takashi; Udagawa, Satoshi; Yonezawa, Tetsu

    2013-03-01

    As a new method for nanoparticles preparation, magnetron sputtering of metal atoms and clusters into organic liquids has been intensively used recently. In this study, metallic copper nanoparticles dispersed in pentaerythritol ethoxylate were prepared by this process. Their size control was achieved by controlling the sputtering current. Specific absorption at ca. 580 nm was detected by UV-Vis measurement which is attributed to the specific plasmon absorption of metallic copper. TEM observation also revealed the formation of metallic nanoparticles.

  3. Formation of Ordered Nanoscale Semiconductor Dots by Ion Sputtering.

    PubMed

    Facsko; Dekorsy; Koerdt; Trappe; Kurz; Vogt; Hartnagel

    1999-09-03

    A formation process for semiconductor quantum dots based on a surface instability induced by ion sputtering under normal incidence is presented. Crystalline dots 35 nanometers in diameter and arranged in a regular hexagonal lattice were produced on gallium antimonide surfaces. The formation mechanism relies on a natural self-organization mechanism that occurs during the erosion of surfaces, which is based on the interplay between roughening induced by ion sputtering and smoothing due to surface diffusion.

  4. Improved Reliability of InGaN-Based Light-Emitting Diodes by HfO2 Passivation Layer.

    PubMed

    Park, Seung Hyun; Kim, Yoon Seok; Kim, Tae Hoon; Ryu, Sang Wan

    2016-02-01

    We utilized a passivation layer to improve the leakage current and reliability characteristics of GaN-based light-emitting diodes. The electrical and optical characteristics of the fabricated LEDs were characterized by current-voltage and optical power measurements. The HfO2 passivation layer showed no optical power degradation and suppressed leakage current. The low deposition temper- ature of sputtered HfO2 is responsible for the improved reliability of the LEDs because it suppresses the diffusion of hydrogen plasma into GaN to form harmful Mg-H complexes.

  5. Nanostructured graded-index antireflection layer formation on GaN for enhancing light extraction from light-emitting diodes

    NASA Astrophysics Data System (ADS)

    Dylewicz, R.; Khokhar, A. Z.; Wasielewski, R.; Mazur, P.; Rahman, F.

    2012-05-01

    We describe the fabrication and characterization of a randomly etched gallium nitride (GaN) surface for enhancing light extraction from light-emitting diodes. Our technique uses silica spheres as nano-targets in a sputter-etch process and produces a fine-grained surface with features around 35 nm. The textured surface layer acts as a graded refractive index layer with antireflection properties. Measurements show that photoluminescence intensity from such treated surfaces on a GaN LED wafer increases 2.2 times over that from pristine surfaces. These findings are also supported by computer modelling studies described here.

  6. XPS Study of Plasma- and Argon Ion-Sputtered Polytetrafluoroethylene

    NASA Technical Reports Server (NTRS)

    Golub, Morton A.; Kliss, Mark (Technical Monitor)

    1997-01-01

    The similarity of plasma-polymerized tetrafluoroethylene (PPTFE) and the fluoropolymer film deposited by rf (radio frequency) plasma sputtering (SPTFE) of polytetrafluoroethylene (PTFE), noted earlier in the literature, has been reconfirmed. FT-IR (Fourier Transform Infrared), XPS (X ray Photoelectron Spectroscopy) and UV (ultraviolet) spectroscopy has been employed in apparently the first study to involve preparation of PPTFE and SPTFE in the same reactor and under comparable low-power plasma conditions. Most of the work concerned the use of He or Ar as sputtering gas, but some runs were also carried out with the other rare gases Ne, Kr and Xe. The C1s XPS spectra of SPTFE films displayed a relatively higher content of CF2 groups, and yielded higher F/C (fluorine / carbon) ratios, than PPTFE films, while the SPTFE films were somewhat more transparent in the UV than PPTFE. The F/C ratios for SPTFE were essentially independent of the rare gas used for sputtering. Increasing rf power from 10 to 50 W for Xe plasma-sputtering of PTFE resulted in successively lower F/C ratios (1.55 to 1.21), accompanied by sputtering of the glass reactor occurring at 40 W and above. Some limited XPS, FT-IR and UV data are presented on Ar ion-sputtered PTFE.

  7. Sputtering by the Solar Wind: Effects of Variable Composition

    NASA Technical Reports Server (NTRS)

    Killen, R. M.; Arrell, W. M.; Sarantos, M.; Delory, G. T.

    2011-01-01

    It has long been recognized that solar wind bombardment onto exposed surfaces in the solar system will produce an energetic component to the exospheres about those bodies. Laboratory experiments have shown that there is no increase in the sputtering yield caused by highly charged heavy ions for metallic and for semiconducting surfaces, but the sputter yield can be noticeably increased in the case of a good insulating surface. Recently measurements of the solar wind composition have become available. It is now known that the solar wind composition is highly dependent on the origin of the particular plasma. Using the measured composition of the slow wind, fast wind, solar energetic particle (SEP) population, and coronal mass ejection (CME), broken down into its various components, we have estimated the total sputter yield for each type of solar wind. Whereas many previous calculations of sputtering were limited to the effects of proton bombardment. we show that the heavy ion component. especially the He++ component. can greatly enhance the total sputter yield during times when the heavy ion population is enhanced. We will discuss sputtering of both neutrals and ions.

  8. 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.

  9. Kinetic simulation of neutral particle transport in sputtering processes

    NASA Astrophysics Data System (ADS)

    Trieschmann, Jan; Gallian, Sara; Brinkmann, Ralf Peter; Mussenbrock, Thomas; Ries, Stefan; Bibinov, Nikita; Awakowicz, Peter

    2013-09-01

    For many physical vapor deposition applications using sputtering processes, knowledge about the detailed spatial and temporal evolution of the involved gas species is of great importance. Modeling of the involved gas dynamic and plasma processes is however challenging, because the operating pressure is typically below 1 Pa. In consequence, only kinetic descriptions are appropriate. In order to approach this problem, the dynamics of sputtered particle transport through a neutral gas background is simulated. For this study, a modified version of the three-dimensional Direct Simulation Monte Carlo (DSMC) code dsmcFoam is utilized. The impact of a transient sputtering wind is investigated in a generic reactor geometry, which may be used for dc Magnetron Sputtering (dcMS), High Power Impulse Magnetron Sputtering (HiPIMS), as well as sputtering in capacitively coupled discharges. In the present work a rarefaction of the background gas is observed. Moreover in pulsed mode the temporal dynamics of the rarefaction and subsequent recovery of the background gas is investigated. This work is supported by the German Research Foundation in the frame of TRR 87.

  10. 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

    2017-07-01

    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.

  11. 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.

  12. Determination of deposited flux and energy of sputtered tungsten atoms on every stages of transport in HiPIMS discharge

    NASA Astrophysics Data System (ADS)

    Desecures, M.; de Poucques, L.; Bougdira, J.

    2017-02-01

    A time-resolved tunable diode-laser (DL) induced fluorescence (TR-TDLIF) technique has been used to identify different populations of atoms (on different stages of transport) to determine their corresponding deposited energy and flux. The temporal dimension permits the splitting of the processes of sputtering during the discharge and particles transport in the post-discharge where atoms and flux velocity distribution functions (AVDF, FVDF) of each population were measured varying the discharge parameters (power, voltage, pressure, and distance from target). Tungsten (W) was chosen, being an interesting case in terms of sputtered atom transport, considering its weight which implies weak changes of directivity or energy transfer after collisions with the buffer gas. The high temporal and spectral resolutions of TR-TDLIF are the keys for the distinction of the atoms populations and the stage corresponding to the transition from the ballistic to diffusive regime of transport was observed for the first time and named quasi-diffusive regime. Thus, the ability to dissociate populations of atoms and to determine their deposited flux and energy may be of great interest to adjust film properties as desired for applications.

  13. Kinetic and potential sputtering of an anorthite-like glassy thin film: Sputtering of Anorthite-Like Thin Film

    DOE PAGES

    Hijazi, H.; Bannister, M. E.; Meyer, H. M.; ...

    2017-07-28

    In this paper, we present measurements of He+ and He+2 ion-induced sputtering of an anorthite-like thin film at a fixed solar wind-relevant impact energy of ~0.5 keV/amu using a quartz crystal microbalance approach (QCM) for determination of total absolute sputtering yields. He+2 ions are the most abundant multicharged ions in the solar wind, and increased sputtering by these ions in comparison to equivelocity He+ ions is expected to have the biggest effect on the overall sputtering efficiency of solar wind impact on the Moon. These measurements indicate an almost 70% increase of the sputtering yield for doubly charged incident Hemore » ions compared to that for same velocity He+ impact (14.6 amu/ion for He+2 vs. 8.7 amu/ion for He+). Using a selective sputtering model, the new QCM results presented here, together with previously published results for Ar+q ions and SRIM results for the relevant kinetic-sputtering yields, the effect due to multicharged-solar-wind-ion impact on local near-surface modification of lunar anorthite-like soil is explored. It is shown that the multicharged-solar-wind component leads to a more pronounced and significant differentiation of depleted and enriched surface elements as well as a shortening of the timescale over which such surface-compositional modifications might occur in astrophysical settings. Additionally, to validate previous and future determinations of multicharged-ion-induced sputtering enhancement for those cases where the QCM approach cannot be used, relative quadrupole mass spectrometry (QMS)-based measurements are presented for the same anorthite-like thin film as were investigated by QCM, and their suitability and limitations for charge state-enhanced yield measurements are discussed.« less

  14. Time resolved metal line profile by near-ultraviolet tunable diode laser absorption spectroscopy

    NASA Astrophysics Data System (ADS)

    Vitelaru, C.; de Poucques, L.; Minea, T. M.; Popa, G.

    2011-03-01

    Pulsed systems are extensively used to produce active species such as atoms, radicals, excited states, etc. The tunable diode laser absorption spectroscopy (TD-LAS) is successfully used to quantify the density of absorbing species, but especially for stationary or slow changing systems. The time resolved-direct absorption profile (TR-DAP) measurement method by TD-LAS, with time resolution of μs is proposed here as an extension of the regular use of diode laser absorption spectroscopy. The spectral narrowness of laser diodes, especially in the blue range (˜0.01 pm), combined with the nanosecond fast trigger of the magnetron pulsed plasma and long trace recording on the oscilloscope (period of second scale) permit the detection of the sputtered titanium metal evolution in the afterglow (˜ms). TR-DAP method can follow the time-dependence of the temperature (Doppler profile) and the density (deduced from the absorbance) of any medium and heavy species in a pulsed system.

  15. Estimates of Sputter Yields of Solar-Wind Heavy Ions of Lunar Regolith Materials

    NASA Technical Reports Server (NTRS)

    Barghouty, Abdulmasser F.; Adams, James H., Jr.

    2008-01-01

    At energies of approximately 1 keV/amu, solar-wind protons and heavy ions interact with the lunar surface materials via a number of microscopic interactions that include sputtering. Solar-wind induced sputtering is a main mechanism by which the composition of the topmost layers of the lunar surface can change, dynamically and preferentially. This work concentrates on sputtering induced by solar-wind heavy ions. Sputtering associated with slow (speeds the electrons speed in its first Bohr orbit) and highly charged ions are known to include both kinetic and potential sputtering. Potential sputtering enjoys some unique characteristics that makes it of special interest to lunar science and exploration. Unlike the yield from kinetic sputtering where simulation and approximation schemes exist, the yield from potential sputtering is not as easy to estimate. This work will present a preliminary numerical scheme designed to estimate potential sputtering yields from reactions relevant to this aspect of solar-wind lunar-surface coupling.

  16. Estimates of Sputter Yields of Solar-Wind Heavy Ions of Lunar Regolith Materials

    NASA Technical Reports Server (NTRS)

    Barghouty, Abdulmasser F.; Adams, James H., Jr.

    2008-01-01

    At energies of approximately 1 keV/amu, solar-wind protons and heavy ions interact with the lunar surface materials via a number of microscopic interactions that include sputtering. Solar-wind induced sputtering is a main mechanism by which the composition of the topmost layers of the lunar surface can change, dynamically and preferentially. This work concentrates on sputtering induced by solar-wind heavy ions. Sputtering associated with slow (speeds the electrons speed in its first Bohr orbit) and highly charged ions are known to include both kinetic and potential sputtering. Potential sputtering enjoys some unique characteristics that makes it of special interest to lunar science and exploration. Unlike the yield from kinetic sputtering where simulation and approximation schemes exist, the yield from potential sputtering is not as easy to estimate. This work will present a preliminary numerical scheme designed to estimate potential sputtering yields from reactions relevant to this aspect of solar-wind lunar-surface coupling.

  17. Molecules can be sputtered also from pure metals: sputtering of beryllium hydride by fusion plasma-wall interactions

    NASA Astrophysics Data System (ADS)

    Björkas, C.; Borodin, D.; Kirschner, A.; Janev, R. K.; Nishijima, D.; Doerner, R.; Nordlund, K.

    2013-07-01

    The low-energy erosion mechanisms of first-wall materials subject to a fusion plasma are poorly known theoretically, even though they pose a critical problem for the development of tokamak-like fusion reactors. Using molecular dynamics computer simulations and analytical theory, we have examined the fundamental mechanisms of the erosion of first-wall materials, focusing on molecular release from beryllium surfaces. We show that the observed sputtering of BeD molecules from beryllium when exposed to a D plasma can be explained by the swift chemical sputtering mechanism, and that it also can happen in BeW alloys. This demonstrates that pure metals can, in contrast to conventional wisdom, be sputtered chemically. We also link the simulations of BeD sputtering to the plasma impurity transport code ERO, in order to follow the behavior of sputtered BeD species in a plasma. This multi-scale approach enables direct comparisons with experimental observations of BeD sputtering in the PISCES-B facility.

  18. Ion beam sputter deposited zinc telluride films

    NASA Technical Reports Server (NTRS)

    Gulino, D. A.

    1985-01-01

    Zinc telluride is of interest as a potential electronic device material, particularly as one component in an amorphous superlattice, which is a new class of interesting and potentially useful materials. Some structural and electronic properties of ZnTe films deposited by argon ion beam sputter depoairion are described. Films (up to 3000 angstroms thick) were deposited from a ZnTe target. A beam energy of 1000 eV and a current density of 4 mA/sq. cm. resulted in deposition rates of approximately 70 angstroms/min. The optical band gap was found to be approximately 1.1 eV, indicating an amorphous structure, as compared to a literature value of 2.26 eV for crystalline material. Intrinsic stress measurements showed a thickness dependence, varying from tensile for thicknesses below 850 angstroms to compressive for larger thicknesses. Room temperature conductivity measurement also showed a thickness dependence, with values ranging from 1.86 x to to the -6/ohm. cm. for 300 angstrom film to 2.56 x 10 to the -1/ohm. cm. for a 2600 angstrom film. Measurement of the temperature dependence of the conductivity for these films showed complicated behavior which was thickness dependent. Thinner films showed at least two distinct temperature dependent conductivity mechanisms, as described by a Mott-type model. Thicker films showed only one principal conductivity mechanism, similar to what might be expected for a material with more crystalline character.

  19. Ion beam sputter deposited zinc telluride films

    NASA Technical Reports Server (NTRS)

    Gulino, D. A.

    1986-01-01

    Zinc telluride is of interest as a potential electronic device material, particularly as one component in an amorphous superlattice, which is a new class of interesting and potentially useful materials. Some structural and electronic properties of ZnTe films deposited by argon ion beam sputter deposition are described. Films (up to 3000 angstroms thick) were deposited from a ZnTe target. A beam energy of 1000 eV and a current density of 4 mA/sq cm resulted in deposition rates of approximately 70 angstroms/min. The optical band gap was found to be approximately 1.1 eV, indicating an amorphous structure, as compared to a literature value of 2.26 eV for crystalline material. Intrinsic stress measurements showed a thickness dependence, varying from tensile for thicknesses below 850 angstroms to compressive for larger thicknesses. Room temperature conductivity measurement also showed a thickness dependence, with values ranging from 1.86 x 10 to the -6th/ohm cm for 300 angstrom film to 2.56 x 10 to the -1/ohm cm for a 2600 angstrom film. Measurement of the temperature dependence of the conductivity for these films showed complicated behavior which was thickness dependent. Thinner films showed at least two distinct temperature dependent conductivity mechanisms, as described by a Mott-type model. Thicker films showed only one principal conductivity mechanism, similar to what might be expected for a material with more crystalline character.

  20. Aerosol dynamics in a sputtering DC discharge

    NASA Astrophysics Data System (ADS)

    Michau, A.; Arnas, C.; Hassouni, K.

    2017-04-01

    An aerosol sectional model that describes the space-time evolution of the size distribution of carbon particles produced in a graphite cathode sputtering discharge is presented. The model includes the coupled phenomena of particle growth processes, due to coagulation and molecular surface deposition, particle nucleation as inferred from a molecular growth process, particle charging in the plasma, and particle drift-diffusion transport in the electrode gap. Comparison between simulation results and experiments showed that the model yields a satisfactory prediction of the particle cloud density and particle mean diameter in the electrode gap. It also yields a satisfactory prediction of the particle size distribution. The calculated size distribution shows two particle-populations: a first one with a very small size and just above the nucleus diameter and a second population, with a larger size, that determines the mean-diameter of the particle cloud. The sectional model also shows that simple aerosol models assuming single size particles significantly overestimate the particle density although it yields a satisfactory prediction for the particle size.

  1. 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.

  2. 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.

  3. Annealing of gold nanostructures sputtered on polytetrafluoroethylene

    PubMed Central

    2011-01-01

    Gold nanolayers sputtered on polytetrafluoroethylene (PTFE) surface and their changes induced by post-deposition annealing at 100°C to 300°C are studied. Changes in surface morphology and roughness are examined by atomic force microscopy, electrical sheet resistance by two point technique, zeta potential by electrokinetic analysis and chemical composition by X-ray photoelectron spectroscopy (XPS) in dependence on the gold layer thickness. Transition from discontinuous to continuous gold coverage takes place at the layer thicknesses 10 to 15 nm and this threshold remains practically unchanged after the annealing at the temperatures below 200°C. The annealing at 300°C, however, leads to significant rearrangement of the gold layer and the transition threshold increases to 70 nm. Significant carbon contamination and the presence of oxidized structures on gold-coated samples are observed in XPS spectra. Gold coating leads to a decrease in the sample surface roughness. Annealing at 300°C of pristine PTFE and gold-coated PTFE results in significant increase of the sample surface roughness. PMID:22078024

  4. Sputtered Thallium-Barium Superconducting Thin Films

    NASA Astrophysics Data System (ADS)

    Wu, Changyao

    Thin films, a necessary form of materials for most sensors and electronic applications, of Tl-Ba-Ca-Cu -O have been studied. The samples were prepared by the precursor method. Precursor films of Ba-Ca-Cu-O were first deposited on the single crystal substrates of MgO, LaAlO _3, and SrTiO_3 by rf-magnetron sputtering. The following heat-treatment facilitated the incorporation of thallium into the precursor films and proper phase formation. Processing variables were systematically studied and the resulting films were characterized by X-ray diffraction, scanning electron microscopy, and energy dispersive X-ray spectroscopy. Superconducting microbridges patterned by photolithography and wet chemical etching were used for R-T and I-V characteristics measurements. The resistive broadening of superconducting transition under magnetic fields was discussed in the framework of Anderson -Kim flux-creep theory. The activation energy for the flux -creep appears to be of functional form rm U_{o}~(1-T/ rm T_{c})/B^{1/2}. .

  5. 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.

  6. Xenon Sputter Yield Measurements for Ion Thruster Materials

    NASA Technical Reports Server (NTRS)

    Williams, John D.; Gardner, Michael M.; Johnson, Mark L.; Wilbur, Paul J.

    2003-01-01

    In this paper, we describe a technique that was used to measure total and differential sputter yields of materials important to high specific impulse ion thrusters. The heart of the technique is a quartz crystal monitor that is swept at constant radial distance from a small target region where a high current density xenon ion beam is aimed. Differential sputtering yields were generally measured over a full 180 deg arc in a plane that included the beam centerline and the normal vector to the target surface. Sputter yield results are presented for a xenon ion energy range from 0.5 to 10 keV and an angle of incidence range from 0 deg to 70 deg from the target surface normal direction for targets consisting of molybdenum, titanium, solid (Poco) graphite, and flexible graphite (grafoil). Total sputter yields are calculated using a simple integration procedure and comparisons are made to sputter yields obtained from the literature. In general, the agreement between the available data is good. As expected for heavy xenon ions, the differential and total sputter yields are found to be strong functions of angle of incidence. Significant under- and over-cosine behavior is observed at low- and high-ion energies, respectively. In addition, strong differences in differential yield behavior are observed between low-Z targets (C and Ti) and high-Z targets (Mo). Curve fits to the differential sputter yield data are provided. They should prove useful to analysts interested in predicting the erosion profiles of ion thruster components and determining where the erosion products re-deposit.

  7. The role of surface microstructure in the sputtering of graphite

    SciTech Connect

    Youchison, D.L.; Nahemow, M.D. ); McGrath, R.T. ); Baratta, A.J. )

    1991-05-01

    Extensive exposure to tokamak plasmas may result in significant alterations to the surface microstructure of graphite plasma-facing components. A change in microstructure from a commercial isotropic graphite to an amorphous carbon film may produce a significant change in the total sputtering yield and the level of plasma contamination. To investigate this sensitivity to surface microstructure, sputtering experiments on a variety of graphites with various surface structures were performed using the ion--surface interaction system (ISIS).{sup 1} ISIS is a computerized ion beam sputtering system equipped with twin quartz crystal microbalances capable of simultaneously monitoring both sputtering and redeposition of the beam target material. ISIS was used to obtain sputtering data on two orientations of pyrolytic graphite at seven energies between 100 eV and 10 keV. Helium bombardment perpendicular to the prism plane produced yields 2 to 7 times higher than on the basal plane. Proton bombardment perpendicular to the prism plane produced yields 45% higher than those on the basal plane. Amorphous graphite films produced from Poco AXF-5Q and Union Carbide ATJ graphites using an argon radio-frequency (rf) plasma discharge were also irradiated. Sputtering yields on the amorphous films were as much as 50% to an order of magnitude higher than those measured on commercial bulk samples. Pre and post-irradiation scanning electron microscopy of selected targets was performed to monitor surface microstructure. A structural mechanism responsible for the magnitude of physical sputtering is suggested, and an effective surface binding energy is introduced to quantify this structural dependence.

  8. Sputter-depth profiling for thin-film analysis.

    PubMed

    Hofmann, S

    2004-01-15

    Following a brief historical background, the concepts and the present state of sputter-depth profiling for thin-film analysis are outlined. There are two main branches: either the removed matter (as in mass- or optical-spectroscopy-based secondary-ion mass spectrometry or glow-discharge optical emission spectroscopy), or the remaining surface (as in Auger electron spectroscopy and X-ray photoelectron spectroscopy) is characterized. These complementary methods show the same result if there is no preferential sputtering of a component. The common root of both is the fundamental ion-solid interaction. Understanding of how the latter influences the depth resolution has led to important improvements in experimental profiling conditions such as sample rotation and the use of low-energy ions at glancing incidence. Modern surface-analysis instruments can provide high-resolution depth profiles on the nanometre scale. Mathematical models of different sophistication were developed to allow deconvolution of the measured profile or quantification by reconstruction of the in-depth distribution of composition. For the latter purpose, the usefulness of the so-called mixing-roughness-information (MRI) depth model is outlined on several thin-film structures (e.g. AlAs/GaAs and Si/Ge), including its extension to quantification of sputter-depth profiles in layer structures with preferential sputtering of one component (Ta/Si). Using the MRI model, diffusion coefficients at interfaces as low as 10(-22) m(2) s(-1) can be determined. Fundamental limitations of sputter-depth profiling are mainly traced back to the stochastic nature of primary-particle energy transfer to the sputtered particle, promoting atomic mixing and the development of surface roughness. Owing to more sophisticated experimental methods, such as low-energy cluster ion bombardment, glancing ion incidence or 'backside' sputtering, these ultimate limitations can be reduced to the atomic monolayer scale.

  9. 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

  10. Quantum Noise in Laser Diodes

    NASA Technical Reports Server (NTRS)

    Giacobino, E.; Marin, F.; Bramati, A.; Jost, V.; Poizat, J. Ph.; Roch, J.-F.; Grangier, P.; Zhang, T.-C.

    1996-01-01

    We have investigated the intensity noise of single mode laser diodes, either free-running or using different types of line narrowing techniques at room temperature. We have measured an intensity squeezing of 1.2 dB with grating-extended cavity lasers and 1.4 dB with injection locked lasers (respectively 1.6 dB and 2.3 dB inferred at the laser output). We have observed that the intensity noise of a free-running nominally single mode laser diode results from a cancellation effect between large anti-correlated fluctuations of the main mode and of weak longitudinal side modes. Reducing the side modes by line narrowing techniques results in intensity squeezing.

  11. Megahertz organic/polymer diodes

    DOEpatents

    Katz, Howard Edan; Sun, Jia; Pal, Nath Bhola

    2012-12-11

    Featured is an organic/polymer diode having a first layer composed essentially of one of an organic semiconductor material or a polymeric semiconductor material and a second layer formed on the first layer and being electrically coupled to the first layer such that current flows through the layers in one direction when a voltage is applied in one direction. The second layer is essentially composed of a material whose characteristics and properties are such that when formed on the first layer, the diode is capable of high frequency rectifications on the order of megahertz rectifications such as for example rectifications at one of above 100KHz, 500KhZ, IMHz, or 10 MHz. In further embodiments, the layers are arranged so as to be exposed to atmosphere.

  12. Plasma Studies in Ion Diodes.

    DTIC Science & Technology

    1984-09-01

    high power pulse, with a typical rise time of 10 ns, to a pulsed high current vacuum diode (also variously referred to as an explosive emission , field...instantaneous event. One motivation for such studies was the developement of high voltage devices, such as x - ray tubes. for which vacuum breakdown was...Sources of high current , high voltage particle beams rely on the intermedi- ate phase of vacuum breakdown, between initial plasma formation and gap clo

  13. Molecular diodes in optical rectennas

    NASA Astrophysics Data System (ADS)

    Duché, David; Palanchoke, Ujwol; Terracciano, Luigi; Dang, Florian-Xuan; Patrone, Lionel; Le Rouzo, Judikael; Balaban, Téodore Silviu; Alfonso, Claude; Charai, Ahmed; Margeat, Olivier; Ackermann, Jorg; Gourgon, Cécile; Simon, Jean-Jacques; Escoubas, Ludovic

    2016-09-01

    The photo conversion efficiencies of the 1st and 2nd generat ion photovoltaic solar cells are limited by the physical phenomena involved during the photo-conversion processes. An upper limit around 30% has been predicted for a monojunction silicon solar cell. In this work, we study 3rd generation solar cells named rectenna which could direct ly convert visible and infrared light into DC current. The rectenna technology is at odds with the actual photovoltaic technologies, since it is not based on the use of semi-conducting materials. We study a rectenna architecture consist ing of plasmonic nano-antennas associated with rectifying self assembled molecular diodes. We first opt imized the geometry of plasmonic nano-antennas using an FDTD method. The optimal antennas are then realized using a nano-imprint process and associated with self assembled molecular diodes in 11- ferrocenyl-undecanethiol. Finally, The I(V) characterist ics in darkness of the rectennas has been carried out using an STM. The molecular diodes exhibit averaged rect ification ratios of 5.

  14. A single-molecule diode

    PubMed Central

    Elbing, Mark; Ochs, Rolf; Koentopp, Max; Fischer, Matthias; von Hänisch, Carsten; Weigend, Florian; Evers, Ferdinand; Weber, Heiko B.; Mayor, Marcel

    2005-01-01

    We have designed and synthesized a molecular rod that consists of two weakly coupled electronic π -systems with mutually shifted energy levels. The asymmetry thus implied manifests itself in a current–voltage characteristic with pronounced dependence on the sign of the bias voltage, which makes the molecule a prototype for a molecular diode. The individual molecules were immobilized by sulfur–gold bonds between both electrodes of a mechanically controlled break junction, and their electronic transport properties have been investigated. The results indeed show diode-like current–voltage characteristics. In contrast to that, control experiments with symmetric molecular rods consisting of two identical π -systems did not show significant asymmetries in the transport properties. To investigate the underlying transport mechanism, phenomenological arguments are combined with calculations based on density functional theory. The theoretical analysis suggests that the bias dependence of the polarizability of the molecule feeds back into the current leading to an asymmetric shape of the current–voltage characteristics, similar to the phenomena in a semiconductor diode. PMID:15956208

  15. A single-molecule diode.

    PubMed

    Elbing, Mark; Ochs, Rolf; Koentopp, Max; Fischer, Matthias; von Hänisch, Carsten; Weigend, Florian; Evers, Ferdinand; Weber, Heiko B; Mayor, Marcel

    2005-06-21

    We have designed and synthesized a molecular rod that consists of two weakly coupled electronic pi -systems with mutually shifted energy levels. The asymmetry thus implied manifests itself in a current-voltage characteristic with pronounced dependence on the sign of the bias voltage, which makes the molecule a prototype for a molecular diode. The individual molecules were immobilized by sulfur-gold bonds between both electrodes of a mechanically controlled break junction, and their electronic transport properties have been investigated. The results indeed show diode-like current-voltage characteristics. In contrast to that, control experiments with symmetric molecular rods consisting of two identical pi-systems did not show significant asymmetries in the transport properties. To investigate the underlying transport mechanism, phenomenological arguments are combined with calculations based on density functional theory. The theoretical analysis suggests that the bias dependence of the polarizability of the molecule feeds back into the current leading to an asymmetric shape of the current-voltage characteristics, similar to the phenomena in a semiconductor diode.

  16. High power coherent polarization locked laser diode.

    PubMed

    Purnawirman; Phua, P B

    2011-03-14

    We have coherently combined a broad area laser diode array to obtain high power single-lobed output by using coherent polarization locking. The single-lobed coherent beam is achieved by spatially combining four diode emitters using walk-off crystals and waveplates while their phases are passively locked via polarization discrimination. While our previous work focused on coherent polarization locking of diode in Gaussian beams, we demonstrate in this paper, the feasibility of the same polarization discrimination for locking multimode beams from broad area diode lasers. The resonator is designed to mitigate the loss from smile effect by using retro-reflection feedback in the cavity. In a 980 nm diode array, we produced 7.2 W coherent output with M2 of 1.5x11.5. The brightness of the diode is improved by more than an order of magnitude.

  17. Glass requirements for encapsulating metallurgical diodes

    NASA Astrophysics Data System (ADS)

    Ali, Mir A.; Meldrum, Gerald L.; Krieger, Jeffry M.

    1991-08-01

    Environmental temperature variations cause stresses to develop in structures that contain materials with different coefficients of thermal expansion. Such a condition often exists in glass encapsulated diodes used in the electronic systems. The situation is further aggravated by the metallurgy of the diodes in the form of stresses due to corrosion--the stress corrosion effect. A third factor that introduces stresses in the encapsulated diodes is due to the design of the glass encapsulation. A combination of these factors led to a failure of glass encapsulated diodes and were identified in a recent study conducted at the Technology Support Division (TSD), Electro-Optical and Data Systems Group of Hughes Aircraft Company. A judicious selection of the encapsulating glasses, its properties, and the design of the seal becomes an important factor in the fabrication of a hermetically sealed diode. This paper highlights such failure mechanisms and describes the desirable properties and design requirements of sealing glasses used for encapsulating the diodes.

  18. Vortex diode jet performance and theory

    SciTech Connect

    Houck, E.D.

    1993-12-01

    Fluidics is the technology dealing with the use of a flowing liquid or gas in various devices for controls and fluid transfers. Existing fluidic technology transfers fluid at approximately the same rate as air lifts and jets. A vortex diode combined in parallel with a jet (vortex diode jet) produces significantly higher transfer rates` and retains the fluidic system advantages. This paper presents the proof of concept research and gives design parameters for the vortex diode jet. The goal of this research was to develop a vortex diode jet that would improve fluidic system transfer rates, and to develop and verify the,design equations. Proven design equations could then be used to design, and model vortex diode jet systems. This research has shown that vortex diode jets improve fluidic system transfer rate by up to 60 percent and can be modelled with the design equations.

  19. N-polar InGaN-based LEDs fabricated on sapphire via pulsed sputtering

    NASA Astrophysics Data System (ADS)

    Ueno, Kohei; Kishikawa, Eiji; Ohta, Jitsuo; Fujioka, Hiroshi

    2017-02-01

    High-quality N-polar GaN epitaxial films with an atomically flat surface were grown on sapphire (0001) via pulsed sputtering deposition, and their structural and electrical properties were investigated. The crystalline quality of N-polar GaN improves with increasing film thickness and the full width at half maximum values of the x-ray rocking curves for 0002 and 101 ¯ 2 diffraction were 313 and 394 arcsec, respectively, at the film thickness of 6 μ m . Repeatable p-type doping in N-polar GaN films was achieved using Mg dopant, and their hole concentration and mobility can be controlled in the range of 8 × 1016-2 × 1018 cm-3 and 2-9 cm2V-1s-1, respectively. The activation energy of Mg in N-polar GaN based on a temperature-dependent Hall measurement was estimated to be 161 meV, which is comparable to that of the Ga-polar GaN. Based on these results, we demonstrated the fabrication of N-polar InGaN-based light emitting diodes with the long wavelength up to 609 nm.

  20. Chemical modification of sputtered amorphous-carbon surfaces

    NASA Astrophysics Data System (ADS)

    Leezenberg, Pieter B.; Johnston, William H.; Tyndall, George W.

    2001-03-01

    Methods to chemically passivate the surfaces of amorphous-carbon films (a-C) produced by dc magnetron sputtering were studied. The chemical composition of carbon surfaces produced via sputtering are dependent upon the environment to which the carbon is exposed immediately following deposition. When the sputtered film is vented to ambient conditions, free radicals produced at the surface during the deposition process are quenched by reaction with oxygen and/or water to form an oxidized, hydrophilic surface. If the sputtered carbon film is, however, exposed to a reactive gas prior to venting to ambient, the chemical nature of the resulting surface can be modified substantially. Specifically, a less highly oxidized and much more hydrophobic carbon surface is produced when the surface free radicals are quenched via either an addition reaction (demonstrated with a fluorinated olefin) or a hydrogen abstraction reaction (demonstrated with two alkyl amines). Chemical modification of amorphous-carbon films can also be accomplished by performing the sputtering in a reactive plasma formed from mixtures of argon with molecular hydrogen, amines, and perfluorocarbons. The elemental composition of these films, and the relative reactivity of the surfaces formed, were investigated via x-ray photoelectron spectroscopy and contact-angle goniometry, respectively. In the case of sputtering with a mixture of argon and hydrogen, increasing the hydrogen flow results in an increase in the amount of hydrogen incorporated into the carbon film and a decrease in the surface free energy. Sputtering in diethylamine produces an amorphous-carbon film into which nitrogen is incorporated. The free energies of the a-C:N surfaces produced in this process are similar to those of the a-C:H films. Sputtering in a fluorocarbon vapor results in the incorporation of fluorine into the film structure and the formation of very low free-energy surfaces. Increasing the concentration of the fluorocarbon in the

  1. Sputtering from a Liquid Phase Gallium-Indium Eutectic Alloy

    NASA Astrophysics Data System (ADS)

    Hubbard, Kevin Mark

    Sputtering experiments were performed with a liquid -phase Ga-In eutectic alloy target. The bulk composition of the eutectic alloy is 16.5 at% In, but thermodynamic surface-segregation results in a surface monolayer of >94 at% In. Angular distributions and partial sputtering yields were measured for 3, 25, and 50 keV Ar ^{+} bombardment. Comparison of the sputtered-flux composition with the alloy surface composition profile allowed calculation of the fraction of sputtered atoms originating from the first atomic layer. The result was found to be ~0.87 +/- _sp{0.03} {0.05} at 25 and 50 keV, and increased to 0.94 +/- _sp{0.04 }{0.06} at 3 keV. The increase may reflect a decrease in the average energy of recoil atoms within collision cascades, because fewer second layer recoil atoms would be able to penetrate the surface layer. Low-energy (4-6 eV) secondary-ion mass spectra were measured for Ne^{+}, Ar^{+}, Kr^ {+}, and Xe^{+} bombardment in the energy range of 25-250 keV. The intensity ratio I(In^{+})/I(Ga ^{+}) was found to be independent of projectile energy, as expected from the collision cascade theory of sputtering. However, a systematic increase, of ~25%, was observed as the projectile mass was increased from that of Ne to that of Xe. This was estimated to correspond to an increase of 5% in the fraction of sputtered atoms originating from the first atomic layer. Molecular/atomic ion yield ratios were measured for 25-250 keV Ne^{+}, Ar^{+}, Kr^ {+}, and Xe^{+} bombardment of Ga and In elemental standards, and were found to be nearly independent of both projectile energy and mass. A published theory based on the recombination of independently sputtered neutral constituents predicts a relative yield proportional to the sputtering yield. The discrepancy may be explained if sputtered molecules are primarily formed when a single recoil atom causes the correlated ejection of several atoms from a localized region of the surface.

  2. Semiconductor Laser Diodes and the Design of a D.C. Powered Laser Diode Drive Unit

    DTIC Science & Technology

    1988-06-01

    i FILE c(OP!; NAVAL POSTGRADUATE SCHOOL Monterey, California 00 ,, STAES THESIS SEMICONDUCTOR LASER DIODES AND THE DESIGN OF A D.C. POWERED LASER...the design of a laser diode modulation circuit is the determination of the input imped- ence and equivalent circuit of the laser diode and packag- ing...current source with a high internal impedance as compared to the input imped- ance of the laser. [Ref. l:p. 33] Summarizing the above, laser diodes

  3. Design, Fabrication and Characterization of MIM Diodes and Frequency Selective Thermal Emitters for Solar Energy Harvesting and Detection Devices

    NASA Astrophysics Data System (ADS)

    Sharma, Saumya

    Energy harvesting using rectennas for infrared radiation continues to be a challenge due to the lack of fast switching diodes capable of rectification at THz frequencies. Metal insulator metal diodes which may be used at 30 THz must show adequate nonlinearity for small signal rectification such as 30 mV. In a rectenna assembly, the voltage signal received as an output from a single nanoantenna can be as small as ~30microV. Thus, only a hybrid array of nanoantennas can be sufficient to provide a signal in the ~30mV range for the diode to be able to rectify around 30THz. A metal-insulator-metal diode with highly nonlinear I-V characteristics is required in order for such small signal rectification to be possible. Such diode fabrication was found to be faced with two major fabrication challenges. The first one being the lack of a precisely controlled deposition process to allow a pinhole free insulator deposition less than 3nm in thickness. Another major challenge is the deposition of a top metal contact on the underlying insulating thin film. As a part of this research study, most of the MIM diodes were fabricated using Langmuir Blodgett monolayers deposited on a thin Ni film that was sputter coated on a silicon wafer. UV induced polymerization of the Langmuir Blodgett thin film was used to allow intermolecular crosslinking. A metal top contact was sputtered onto the underlying Langmuir Blodgett film assembly. In addition to material characterization of all the individual films using IR, UV-VIS spectroscopy, electron microscopy and atomic force microscopy, the I-V characteristics, resistance, current density, rectification ratio and responsivity with respect to the bias voltage were also measured for the electrical characterization of these MIM diodes. Further improvement in the diode rectification ratio and responsivity was obtained with Langmuir Blodgett films grown by the use of horizontally oriented organic molecules, due to a smaller tunneling distance that

  4. Sputter deposition of nanocrystalline beta-SiC films and molecular dynamics simulations of the sputter process.

    PubMed

    Ziebert, Carlos; Ye, Jian; Ulrich, Sven; Prskalo, Alen-Pilip; Schmauder, Siegfried

    2010-02-01

    Thin nanocrystalline films of silicon carbide (SiC) have been deposited on Si substrates by rf magnetron sputtering in pure Ar atmosphere. Simultaneously classical molecular dynamics (MD) simulations of sputtering of beta-SiC by Ar atoms were performed using IMD and Materials Explorer software with a combination of the Tersoff and the Ziegler-Biersack-Littmark (ZBL) potential in order to get more insight into the sputter process. In experiments the bias voltage (0 to -40 V) has been varied at constant substrate temperature of 900 degrees C to investigate the influence on the composition, the constitution and the mechanical properties of crystalline beta-SiC films. At second the substrate temperature has been varied between 900 degrees C and 100 degrees C to find the minimum substrate temperature that is needed to get nanocrystalline beta-SiC under the applied sputter conditions (ceramic SiC target, 300 W rf power, 18 cm target-substrate distance, 50 sccm Ar gas flow, 0.26 Pa total gas pressure). The films have been characterized by electron probe micro-analysis (EPMA), X-ray diffraction (XRD), Raman spectroscopy and atomic force microscopy (AFM). Hardness and residual stress have been investigated by nanoindentation and wafer bending. In the MD simulations the sputter yield was determined as a function of the energy of the incident Ar atoms (in the interesting range for sputter deposition, i.e., 50-1000 eV). To our knowledge this is the first time that the sputter yield of a SiC target was determined as a function of the energy of the incident Ar atoms in the low energy range by using MD simulations and compared with experimental results.

  5. Reconstructing accurate ToF-SIMS depth profiles for organic materials with differential sputter rates

    PubMed Central

    Taylor, Adam J.; Graham, Daniel J.; Castner, David G.

    2015-01-01

    To properly process and reconstruct 3D ToF-SIMS data from systems such as multi-component polymers, drug delivery scaffolds, cells and tissues, it is important to understand the sputtering behavior of the sample. Modern cluster sources enable efficient and stable sputtering of many organics materials. However, not all materials sputter at the same rate and few studies have explored how different sputter rates may distort reconstructed depth profiles of multicomponent materials. In this study spun-cast bilayer polymer films of polystyrene and PMMA are used as model systems to optimize methods for the reconstruction of depth profiles in systems exhibiting different sputter rates between components. Transforming the bilayer depth profile from sputter time to depth using a single sputter rate fails to account for sputter rate variations during the profile. This leads to inaccurate apparent layer thicknesses and interfacial positions, as well as the appearance of continued sputtering into the substrate. Applying measured single component sputter rates to the bilayer films with a step change in sputter rate at the interfaces yields more accurate film thickness and interface positions. The transformation can be further improved by applying a linear sputter rate transition across the interface, thus modeling the sputter rate changes seen in polymer blends. This more closely reflects the expected sputtering behavior. This study highlights the need for both accurate evaluation of component sputter rates and the careful conversion of sputter time to depth, if accurate 3D reconstructions of complex multi-component organic and biological samples are to be achieved. The effects of errors in sputter rate determination are also explored. PMID:26185799

  6. Reconstructing accurate ToF-SIMS depth profiles for organic materials with differential sputter rates.

    PubMed

    Taylor, Adam J; Graham, Daniel J; Castner, David G

    2015-09-07

    To properly process and reconstruct 3D ToF-SIMS data from systems such as multi-component polymers, drug delivery scaffolds, cells and tissues, it is important to understand the sputtering behavior of the sample. Modern cluster sources enable efficient and stable sputtering of many organics materials. However, not all materials sputter at the same rate and few studies have explored how different sputter rates may distort reconstructed depth profiles of multicomponent materials. In this study spun-cast bilayer polymer films of polystyrene and PMMA are used as model systems to optimize methods for the reconstruction of depth profiles in systems exhibiting different sputter rates between components. Transforming the bilayer depth profile from sputter time to depth using a single sputter rate fails to account for sputter rate variations during the profile. This leads to inaccurate apparent layer thicknesses and interfacial positions, as well as the appearance of continued sputtering into the substrate. Applying measured single component sputter rates to the bilayer films with a step change in sputter rate at the interfaces yields more accurate film thickness and interface positions. The transformation can be further improved by applying a linear sputter rate transition across the interface, thus modeling the sputter rate changes seen in polymer blends. This more closely reflects the expected sputtering behavior. This study highlights the need for both accurate evaluation of component sputter rates and the careful conversion of sputter time to depth, if accurate 3D reconstructions of complex multi-component organic and biological samples are to be achieved. The effects of errors in sputter rate determination are also explored.

  7. Thermal (Silicon Diode) Data Acquisition Systems

    NASA Technical Reports Server (NTRS)

    Wright, Ernest; Kegley, Jeff

    2008-01-01

    Marshall Space Flight Center s X-ray Cryogenic Facility (XRCF) has been performing cryogenic testing to 20 Kelvin since 1999. Two configurations for acquiring data from silicon diode temperature sensors have been implemented at the facility. The facility's environment is recorded via a data acquisition system capable of reading up to 60 silicon diodes. Test article temperature is recorded by a second data acquisition system capable of reading 150+ silicon diodes. The specifications and architecture of both systems will be presented.

  8. Thermal (Silicon Diode) Data Acquisition System

    NASA Technical Reports Server (NTRS)

    Kegley, Jeffrey

    2008-01-01

    Marshall Space Flight Center's X-ray Calibration Facility (XRCF) has been performing cryogenic testing to 20 Kelvin since 1999. Two configurations for acquiring data from silicon diode temperature sensors have been implemented at the facility. The facility's environment is recorded via a data acquisition system capable of reading up to 60 silicon diodes. Test article temperature is recorded by a second data acquisition system capable of reading 150+ silicon diodes. The specifications and architecture of both systems will be presented.

  9. Thermal (Silicon Diode) Data Acquisition System

    NASA Technical Reports Server (NTRS)

    Kegley, Jeffrey

    2008-01-01

    Marshall Space Flight Center's X-ray Calibration Facility (XRCF) has been performing cryogenic testing to 20 Kelvin since 1999. Two configurations for acquiring data from silicon diode temperature sensors have been implemented at the facility. The facility's environment is recorded via a data acquisition system capable of reading up to 60 silicon diodes. Test article temperature is recorded by a second data acquisition system capable of reading 150+ silicon diodes. The specifications and architecture of both systems will be presented.

  10. Thermic diode performance characteristics and design manual

    NASA Technical Reports Server (NTRS)

    Bernard, D. E.; Buckley, S.

    1979-01-01

    Thermic diode solar panels are a passive method of space and hot water heating using the thermosyphon principle. Simplified methods of sizing and performing economic analyses of solar heating systems had until now been limited to passive systems. A mathematical model of the thermic diode including its high level of stratification has been constructed allowing its performance characteristics to be studied. Further analysis resulted in a thermic diode design manual based on the f-chart method.

  11. Schlieren with a laser diode source

    NASA Astrophysics Data System (ADS)

    Burner, A. W.; Franke, J. M.

    1981-10-01

    The use of a laser diode as a light source for a schlieren system designed to study phase objects such as a wind-tunnel flow is explored. A laser diode schlieren photograph and a white light schlieren photograph (zirconium arc source) are presented for comparison. The laser diode has increased sensitivity, compared with light schlieren, without appreciable image degradiation, and is an acceptable source for schlieren flow visualization.

  12. Sputter deposition with nearly-parallel coating flux

    SciTech Connect

    Patten, J.W.; McClanahan, E.D.; Moss, R.W.; Bayne, M.A.

    1981-04-01

    A method for producing a dense, nearly-parallel flux of sputtered atoms is described. This method allows sputter depositing films having substantially 100% of theoretical density. The sputtering chamber contains a target having a surface that is substantially parallel to the direction of the particles impinging upon the substrate surface, the distance between the most remote portion of the substrate surface receiving the particles and the target surface emitting the particles in a direction parallel to the substrate surface being relatively small. The pressure in the vessel is maintained less than about .65 Pa to limit scattering and permit line-of-sight deposition. The angles of incidence of the particles impinging upon the substrate surface do not vary greatly even when the target surface area is greatly expanded to increase the deposition rate. An experimental sputtering system is described. Deposition rates are given as a function of distance from the target edge and distance from the target plane. Metallography of sputter deposited Ni is presented.

  13. Nitinol: Tubing versus sputtered film - microcleanliness and corrosion behavior.

    PubMed

    Wohlschlögel, Markus; Lima de Miranda, Rodrigo; Schüßler, Andreas; Quandt, Eckhard

    2016-08-01

    Corrosion behavior and microcleanliness of medical-device grade Nitinol tubing (Nix Ti1- x , x = 0.51; outer diameter 7 mm, wall thickness 0.5 mm), drawn from various ingot qualities, are compared to the characteristics of sputtered Nitinol film material (Nix Ti1- x , x = 0.51; thickness 50 µm). Electropolished tubing half-shell samples are tested versus as-received sputtered film samples. Inclusion size distributions are assessed using quantitative metallography and corrosion behavior is investigated by potentiodynamic polarization testing in phosphate-buffered saline at body temperature. For the sputtered film samples, the surface chemistry is additionally analyzed employing Auger Electron Spectroscopy (AES) composition-depth profiling. Results show that the fraction of breakdowns in the potentiodynamic polarization test correlates with number and size of the inclusions in the material. For the sputtered Nitinol film material no inclusions were detectable by light microscopy on the one hand and no breakdowns were found in the potentiodynamic polarization test on the other hand. As for electropolished Nitinol, the sputtered Nitinol film material reveals Nickel depletion and an Oxygen-to-Titanium intensity ratio of ∼2:1 in the surface oxide layer, as measured by AES. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 104B: 1176-1181, 2016.

  14. Kinematic and thermodynamic effects on liquid metal sputtering

    NASA Astrophysics Data System (ADS)

    Allain, J. P.; Ruzic, D. N.

    2000-10-01

    The absolute sputtering yields of D+, He+ and Li+ on solid, liquid lithium and liquid tin-lithium have been successfully measured and modeled at low energies [1-3]. The Ion-surface InterAction Experiment (IIAX) is used to determine the dependence of Li erosion on temperature and physical sputtering. Preliminary data shows that for He+ bombardment of liquid phase lithium, the physical sputtering yield increases with increasing target temperature. A Colutron ion source is used to create and accelerate gaseous or metal ions onto a molten metal target. The liquid metal targets are heated past their melting point to various temperatures, where the surface oxide layer is plasma cleaned and immediately irradiated with D+, Li+ or He+ ion beams, at each temperature. The evaporated flux at each temperature is measured before and after beam irradiation. The fraction of Li atoms sputtered as ions, is also measured as a function of temperature. Modeling of the absolute sputtering yield is accomplished by VFTRIM-3D, a variant of the TRIM-SP code [4]. [1] J.P. Allain and D.N. Ruzic, submitted Nuclear Fusion April 2000. [2] J.P. Allain, M.R. Hendricks, D.N. Ruzic, submitted J. Nucl. Mater. May 2000 [3] J.P. Allain, M.R. Hendricks, D.N. Ruzic, submitted J. Nucl. Mater. May 2000 [4] D.N. Ruzic, Nuclear Instrum. and Methods in Phys. Res. B47 (1990) pp. 118-125

  15. Fusion sputtering for bonding to zirconia-based materials.

    PubMed

    Aboushelib, Moustafa N

    2012-08-01

    To evaluate the influence of fusion sputtering on zirconia-resin microtensile bond strength after 6 months of water storage. Zirconia disks received one of the following surface treatments: particle abrasion with 50-µm aluminum oxide particles or fusion sputtering, while as-sintered specimens served as a control. The prepared zirconia disks (Lava Zirconia) were bonded to pre-aged composite disks (Filtek Z250) using a phosphatemonomer- containing resin cement (RelyX Unicem), and the bonded specimens were sectioned into micro-bars (1 x 1 x 6 mm) which were either immediately tested or after 6 months of water storage (n = 25). Scanning electron microscopy (SEM) and surface roughness were performed for the prepared specimens. Data were analyzed using two-way ANOVA (α = 0.05). Particle abrasion (33.1 MPa) and fusion sputtering (42.5 MPa) produced significantly higher MTBS values and resisted degradation after 6 months of water storage, while as-sintered specimens (12.4 MPa) demonstrated a significant reduction in bond strength after water storage (2.9 MPa). SEM examination indicated that fusion sputtering resulted in the creation of retentive zirconia beads on the treated surface, which enhanced micromechanical retention with adhesive resin and prevented interfacial failure. Fusion sputtering is a new and a simple method suitable for enhancing the bond strength of adhesive resins to zirconia-based frameworks.

  16. 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.

  17. Sputter deposition for multi-component thin films

    DOEpatents

    Krauss, Alan R.; Auciello, Orlando

    1990-01-01

    Ion beam sputter-induced deposition using a single ion beam and a multicomponent target is capable of reproducibly producing thin films of arbitrary composition, including those which are close to stoichiometry. Using a quartz crystal deposition monitor and a computer controlled, well-focused ion beam, this sputter-deposition approach is capable of producing metal oxide superconductors and semiconductors of the superlattice type such as GaAs-AlGaAs as well as layered metal/oxide/semiconductor/superconductor structures. By programming the dwell time for each target according to the known sputtering yield and desired layer thickness for each material, it is possible to deposit composite films from a well-controlled sub-monolayer up to thicknesses determined only by the available deposition time. In one embodiment, an ion beam is sequentially directed via a set of X-Y electrostatic deflection plates onto three or more different element or compound targets which are constituents of the desired film. In another embodiment, the ion beam is directed through an aperture in the deposition plate and is displaced under computer control to provide a high degree of control over the deposited layer. In yet another embodiment, a single fixed ion beam is directed onto a plurality of sputter targets in a sequential manner where the targets are each moved in alignment with the beam under computer control in forming a multilayer thin film. This controlled sputter-deposition approach may also be used with laser and electron beams.

  18. Sputter deposition for multi-component thin films

    DOEpatents

    Krauss, A.R.; Auciello, O.

    1990-05-08

    Ion beam sputter-induced deposition using a single ion beam and a multicomponent target is capable of reproducibly producing thin films of arbitrary composition, including those which are close to stoichiometry. Using a quartz crystal deposition monitor and a computer controlled, well-focused ion beam, this sputter-deposition approach is capable of producing metal oxide superconductors and semiconductors of the superlattice type such as GaAs-AlGaAs as well as layered metal/oxide/semiconductor/superconductor structures. By programming the dwell time for each target according to the known sputtering yield and desired layer thickness for each material, it is possible to deposit composite films from a well-controlled sub-monolayer up to thicknesses determined only by the available deposition time. In one embodiment, an ion beam is sequentially directed via a set of X-Y electrostatic deflection plates onto three or more different element or compound targets which are constituents of the desired film. In another embodiment, the ion beam is directed through an aperture in the deposition plate and is displaced under computer control to provide a high degree of control over the deposited layer. In yet another embodiment, a single fixed ion beam is directed onto a plurality of sputter targets in a sequential manner where the targets are each moved in alignment with the beam under computer control in forming a multilayer thin film. This controlled sputter-deposition approach may also be used with laser and electron beams. 10 figs.

  19. Simple model of surface roughness for binary collision sputtering simulations

    NASA Astrophysics Data System (ADS)

    Lindsey, Sloan J.; Hobler, Gerhard; Maciążek, Dawid; Postawa, Zbigniew

    2017-02-01

    It has been shown that surface roughness can strongly influence the sputtering yield - especially at glancing incidence angles where the inclusion of surface roughness leads to an increase in sputtering yields. In this work, we propose a simple one-parameter model (the "density gradient model") which imitates surface roughness effects. In the model, the target's atomic density is assumed to vary linearly between the actual material density and zero. The layer width is the sole model parameter. The model has been implemented in the binary collision simulator IMSIL and has been evaluated against various geometric surface models for 5 keV Ga ions impinging an amorphous Si target. To aid the construction of a realistic rough surface topography, we have performed MD simulations of sequential 5 keV Ga impacts on an initially crystalline Si target. We show that our new model effectively reproduces the sputtering yield, with only minor variations in the energy and angular distributions of sputtered particles. The success of the density gradient model is attributed to a reduction of the reflection coefficient - leading to increased sputtering yields, similar in effect to surface roughness.

  20. Lower-Thermosphere Metals and High Altitude Meteoroid Sputtering

    NASA Astrophysics Data System (ADS)

    Raizada, S.; Mathews, J. D.; Kesaraju, S.

    2016-12-01

    Recent lidar observations of atomic Fe, Na, and K at altitudes well above the traditional meteor zone violate the usual assumptions regarding atmospheric metals. While suggested sources of these metals include ion-to-neutral conversion and rapid vertical bulk transport due to intense acoustic-gravity wave breaking, we suggest a direct source. That is, confirmation of radar and optical meteors at altitudes well above the ablation-defined meteor zone points to a direct source of these high-altitude metals due to sputtering of cold, fast meteoroids. Interesting complications to this scenario arise as many of these high altitude meteoroids appear to be fragmenting suggesting these are complex "dirty-ice" and "dust-ball" meteoroids comprised of small, dense grains weakly bound together by more volatile substances. As they enter the 150-200 km atmosphere these meteoroids may disperse into a more extended "coma" that presents a more complex interaction region and interaction process with the atmosphere. We discuss sputtering, the impact energies needed for onset of sputtering, sputtering yield, and the observational evidence available for interpretation of meteoroid sputtering as a source of aeronomically interesting metals above the classical meteor zone.

  1. Measurements and Modelling of Sputtering Rates with Low Energy Ions

    NASA Astrophysics Data System (ADS)

    Ruzic, David N.; Smith, Preston C.; Turkot, Robert B., Jr.

    1996-10-01

    The angular-resolved sputtering yield of Be by D+, and Al by Ar+ was predicted and then measured. A 50 to 1000 eV ion beam from a Colutron was focused on to commercial grade and magnetron target grade samples. The S-65 C grade beryllium samples were supplied by Brush Wellman and the Al samples from TOSOH SMD. In our vacuum chamber the samples can be exposed to a dc D or Ar plasma to remove oxide, load the surface and more-nearly simulate steady state operating conditions in the plasma device. The angular distribution of the sputtered atoms was measured by collection on a single crystal graphite witness plate. The areal density of Be or Al (and BeO2 or Al2O3, after exposure to air) was then measured using a Scanning Auger Spectrometer. Total yield was also measured by deposition onto a quartz crystal oscillator simultaneously to deposition onto the witness plate. A three dimensional version of vectorized fractal TRIM (VFTRIM3D), a Monte-Carlo computer code which includes surface roughness characterized by fractal geometry, was used to predict the angular distribution of the sputtered particles and a global sputtering coefficient. Over a million trajectories were simulated for each incident angle to determine the azimuthal and polar angle distributions of the sputtered atoms. The experimental results match closely with the simulations for total yield, while the measured angular distributions depart somewhat from the predicted cosine curve.

  2. Dynamical simulation of sputtering and reflection from a ternary alloy

    NASA Astrophysics Data System (ADS)

    Ishida, M.; Yamaguchi, Y.; Yoshinaga, H.; Yamamura, Y.

    The sputtering and the reflection from a Tb0.2Fe0.7Co0.1 alloy due to Ar+ ion bombardment have been investigated by the Monte Carlo simulation code ACAT-DIFFUSE which include the compositional change induced by ion influence. In the Tb-Fe-Co system, Fe atoms are preferentially sputtered. The atomic size of a Tb atom is the largest of these three atoms, and so Tb atoms trap preferentially in vacancies. The steady-state concentration of Tb atoms at the topmost layer is larger than the bulk concentration for the low energy ions due to radiation-induced segregation and preferential sputtering of Fe atoms. As the ion fluence increases, the atomic fractions of sputtered atoms calculated by the ACAT-DIFFUSE code become those of the bulk concentration. The depth profiles of each element at the steady state depend on the incident energy. The total sputtering yield and the reflection coefficient from a Tb-Fe-Co alloy calculated by the ACAT-DIFFUSE code are larger than those by the ACAT code at near-threshold energies, where the ACAT code does not include the ion-influence effect. The energy spectra of back-scattered Ar atoms from the present ternary alloy have very similar profiles to those from a monoatomic Tb target, especially for low-energy Ar+ ions.

  3. 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.

  4. Solar wind sputtering effects in the Martian atmosphere

    NASA Technical Reports Server (NTRS)

    Watson, C. C.; Haff, P. K.; Kellogg, W. K.

    1979-01-01

    A Monte Carlo simulation of the sputtering of the upper atmosphere of Mars by the solar wind was performed. The calculated sputtering yields imply loss rates (molecules/cm square - sec escaping the planet) for carbon dioxide, carbon, and oxygen of R(CO2) = 2.6 X 1000000/cm square - sec, R(C) = 6.6 X 1000000/cm square - sec, and R(O) = 7.7 X 1000000/cm - sec. The total mass loss by sputtering is only about 10% of that due to chemical and photo-chemical processes, but sputtering provides a major exospheric sink for carbon. The erosion process described here preferentially removes the lighter components of the atmosphere. Calculations based on a Monte Carlo simulation suggest that for a model atmosphere, 97% of the N2 and 33% of the CO2 originally present may have been sputtered away over 4.5 X 10 to the 9th power y. In the same length of time the (15)N/(14)N isotopic ratio for the bulk atmosphere would have increased by a factor 1.7.

  5. Linear stability analysis of the Vlasov-Poisson equations in high density plasmas in the presence of crossed fields and density gradients

    NASA Technical Reports Server (NTRS)

    Kaup, D. J.; Hansen, P. J.; Choudhury, S. Roy; Thomas, Gary E.

    1986-01-01

    The equations for the single-particle orbits in a nonneutral high density plasma in the presence of inhomogeneous crossed fields are obtained. Using these orbits, the linearized Vlasov equation is solved as an expansion in the orbital radii in the presence of inhomogeneities and density gradients. A model distribution function is introduced whose cold-fluid limit is exactly the same as that used in many previous studies of the cold-fluid equations. This model function is used to reduce the linearized Vlasov-Poisson equations to a second-order ordinary differential equation for the linearized electrostatic potential whose eigenvalue is the perturbation frequency.

  6. Investigation of Diode Pumped Alkali Laser Atmospheric Transmission Using Tunable Diode Laser Absorption Spectroscopy

    DTIC Science & Technology

    2012-09-01

    101 325 Pa = 760 Torr † NIST 2006 CODATA recommended values 98 Appendix B. Alkali Data Potassium Properties Table 3. Potassium (K) physical...INVESTIGATION OF DIODE PUMPED ALKALI LASER ATMOSPHERIC TRANSMISSION USING TUNABLE DIODE LASER ABSORPTION SPECTROSCOPY DISSERTATION Christopher A... ALKALI LASER ATMOSPHERIC TRANSMISSION USING TUNABLE DIODE LASER ABSORPTION SPECTROSCOPY DISSERTATION Presented to the Faculty Graduate School of

  7. Effects of radiation on laser diodes.

    SciTech Connect

    Phifer, Carol Celeste

    2004-09-01

    The effects of ionizing and neutron radiation on the characteristics and performance of laser diodes are reviewed, and the formation mechanisms for nonradiative recombination centers, the primary type of radiation damage in laser diodes, are discussed. Additional topics include the detrimental effects of aluminum in the active (lasing) volume, the transient effects of high-dose-rate pulses of ionizing radiation, and a summary of ways to improve the radiation hardness of laser diodes. Radiation effects on laser diodes emitting in the wavelength region around 808 nm are emphasized.

  8. Advances in high power semiconductor diode lasers

    NASA Astrophysics Data System (ADS)

    Ma, Xiaoyu; Zhong, Li

    2008-03-01

    High power semiconductor lasers have broad applications in the fields of military and industry. Recent advances in high power semiconductor lasers are reviewed mainly in two aspects: improvements of diode lasers performance and optimization of packaging architectures of diode laser bars. Factors which determine the performance of diode lasers, such as power conversion efficiency, temperature of operation, reliability, wavelength stabilization etc., result from a combination of new semiconductor materials, new diode structures, careful material processing of bars. The latest progress of today's high-power diode lasers at home and abroad is briefly discussed and typical data are presented. The packaging process is of decisive importance for the applicability of high-power diode laser bars, not only technically but also economically. The packaging techniques include the material choosing and the structure optimizing of heat-sinks, the bonding between the array and the heat-sink, the cooling and the fiber coupling, etc. The status of packaging techniques is stressed. There are basically three different diode package architectural options according to the integration grade. Since the package design is dominated by the cooling aspect, different effective cooling techniques are promoted by different package architectures and specific demands. The benefit and utility of each package are strongly dependent upon the fundamental optoelectronic properties of the individual diode laser bars. Factors which influence these properties are outlined and comparisons of packaging approaches for these materials are made. Modularity of package for special application requirements is an important developing tendency for high power diode lasers.

  9. Excess noise in tunable diode lasers

    NASA Technical Reports Server (NTRS)

    Rowland, C. W.

    1981-01-01

    The method and the apparatus for identifying excess-noise regions in tunable diode lasers are described. These diode lasers exhibit regions of excess noise as their wavelength is tuned. If a tunable diode laser is to be used as a local oscillator in a superheterodyne optical receiver, these excess-noise regions severely degrade the performance of the receiver. Measurement results for several tunable diode lasers are given. These results indicate that excess noise is not necessarily associated with a particular wavelength, and that it is possible to select temperature and injection current such that the most ideal performance is achieved.

  10. High power impulse magnetron sputtering: Current-voltage-timecharacteristics indicate the onset of sustained self-sputtering

    SciTech Connect

    Anders, Andre; Andersson, Joakim; Ehiasarian, Arutiun

    2007-08-03

    The commonly used current-voltage characteristics are foundinadequate for describing the pulsed nature of the high power impulsemagnetron sputtering (HIPIMS) discharge, rather, the description needs tobe expanded to current-voltage-time characteristics for each initial gaspressure. Using different target materials (Cu, Ti, Nb, C, W, Al, Cr) anda pulsed constant-voltage supply it is shown that the HIPIMS dischargestypically exhibit an initial pressure dependent current peak followed bya second phase that is power and material dependent. This suggests thatthe initial phase of a HIPIMS discharge pulse is dominated by gas ionswhereas the later phase has a strong contribution from self-sputtering.For some materials the discharge switches into a mode of sustainedself-sputtering. The very large differences between materials cannot beascribed to the different sputter yields but they indicate thatgeneration and trapping ofsecondary electrons plays a major role forcurrent-voltage-time characteristics. In particular, it is argued thatthe sustained self-sputtering phase is associated with thegeneration ofmultiply charged ions because only they can cause potential emission ofsecondary electrons whereas the yield caused by singly charged metal ionsis negligibly small.

  11. High power impulse magnetron sputtering: Current-voltage-time characteristics indicate the onset of sustained self-sputtering

    NASA Astrophysics Data System (ADS)

    Anders, André; Andersson, Joakim; Ehiasarian, Arutiun

    2007-12-01

    The commonly used current-voltage characteristics are found inadequate for describing the pulsed nature of the high power impulse magnetron sputtering (HIPIMS) discharge; rather, the description needs to be expanded to current-voltage-time characteristics for each initial gas pressure. Using different target materials (Cu, Ti, Nb, C, W, Al, and Cr) and a pulsed constant-voltage supply, it is shown that the HIPIMS discharges typically exhibit an initial pressure dependent current peak followed by a second phase that is power and material dependent. This suggests that the initial phase of a HIPIMS discharge pulse is dominated by gas ions, whereas the later phase has a strong contribution from self-sputtering. For some materials, the discharge switches into a mode of sustained self-sputtering. The very large differences between materials cannot be ascribed to the different sputter yields but they indicate that generation and trapping of secondary electrons play a major role for current-voltage-time characteristics. In particular, it is argued that the sustained self-sputtering phase is associated with the generation of multiply charged ions because only they can cause potential emission of secondary electrons, whereas the yield caused by singly charged metal ions is negligibly small.

  12. Sputtering - Its relationship to isotopic fractionation on the lunar surface

    NASA Technical Reports Server (NTRS)

    Kerridge, J. F.; Kaplan, I. R.

    1978-01-01

    Silicon, oxygen, sulfur and, possibly, potassium show systematic enrichment of heavier isotopes with increasing soil maturity, probably as a result of solar-wind sputtering, but such a pattern is not exhibited by solar wind-implanted species. Apparently sputter-erosion is not penetrating to their implantation depth, about 200 A. This suggests that sputtering on the moon is being impeded by deposition of vapor condensate following meteoritic impact. Although neither secular variation in the isotopic composition at the source of regolith carbon, probably the solar wind, nor isotopic fractionation of carbon after implantation in the regolith can be ruled out, carbon isotope systematics currently yield no evidence in support of either process.

  13. Physics of arcing, and implications to sputter deposition

    SciTech Connect

    Anders, Andre

    2005-03-15

    Arc and glow discharges are defined based on their cathode processes. Arcs are characterized by collective electron emission, which can be stationary with hot cathodes (thermionic arcs), or non-stationary with cold cathodes (cathodic arcs). A brief review on cathodic arc properties serves as the starting point to better understand arcing phenomena in sputtering. Although arcing occurs in both metal and reactive sputtering, it is more of an issue in the reactive case. Arcing occurs if sufficiently high field strength leads to thermal runaway of an electron emission site. The role of insulating layers and surface potential adjustment through current leakage is highlighted. In the situation of magnetron sputtering with ''racetrack'', the need for a model with two spatial dimensions is shown. In many cases, arcing is initiated by breakdown of dielectric layers and inclusions. It is most efficiently prevented if formation and excessive charge-up of dielectric layers and inclusions can be avoided.

  14. Direct observation of spoke evolution in magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Anders, André; Yang, Yuchen

    2017-08-01

    Ionization zones, also known as spokes, are plasma instabilities manifested as locations of intensified excitation and ionization over a sputtering magnetron's racetrack. Using a linear magnetron and a streak camera, we were able to observe and quantify spoke dynamics. The technique allows us to image the onset and changes for both direct current magnetron sputtering (dcMS) and high power impulse magnetron sputtering (HiPIMS). Spokes in dcMS exhibit substructures. Spokes in HiPIMS are not stable as they shift along the racetrack; rather, they tend to grow or diminish, and they may split and merge. Their evolution can be interpreted in the context of localized electric fields and associated electron heating.

  15. Depth of origin of sputtered atoms for elemental targets

    NASA Astrophysics Data System (ADS)

    Shulga, V. I.; Eckstein, W.

    1998-12-01

    The mean depth of origin of sputtered atoms is an important characteristic of the sputtering process. There exist several theoretical and experimental determinations of the escape depth with different results. To clear up the situation, in the present work a systematic computer simulation study of the mean depth of origin of sputtered atoms is performed. The Monte Carlo program TRIM.SP and the lattice code OKSANA are applied to calculate the distribution of depth of origin and the dependences of the mean depth of origin on the atomic density, N, projectile energy, E, the angle of incidence, α, projectile and target atomic species, Z1 and Z2, as well as the simulation model.

  16. Composition and structure of sputter deposited erbium hydride thin films

    SciTech Connect

    ADAMS,DAVID P.; ROMERO,JUAN A.; RODRIGUEZ,MARK A.; FLORO,JERROLD A.; BANKS,JAMES C.

    2000-05-10

    Erbium hydride thin films are grown onto polished, a-axis {alpha} Al{sub 2}O{sub 3} (sapphire) substrates by reactive ion beam sputtering and analyzed to determine composition, phase and microstructure. Erbium is sputtered while maintaining a H{sub 2} partial pressure of 1.4 x 10{sup {minus}4} Torr. Growth is conducted at several substrate temperatures between 30 and 500 C. Rutherford backscattering spectrometry (RBS) and elastic recoil detection analyses after deposition show that the H/Er areal density ratio is approximately 3:1 for growth temperatures of 30, 150 and 275 C, while for growth above {approximately}430 C, the ratio of hydrogen to metal is closer to 2:1. However, x-ray diffraction shows that all films have a cubic metal sublattice structure corresponding to that of ErH{sub 2}. RBS and Auger electron that sputtered erbium hydride thin films are relatively free of impurities.

  17. Carbon Back Sputter Modeling for Hall Thruster Testing

    NASA Technical Reports Server (NTRS)

    Gilland, James H.; Williams, George J.; Burt, Jonathan M.; Yim, John T.

    2016-01-01

    In support of wear testing for the Hall Effect Rocket with Magnetic Shielding (HERMeS) program, the back sputter from a Hall effect thruster plume has been modeled for the NASA Glenn Research Centers Vacuum Facility 5. The predicted wear at a near-worst case condition of 600 V, 12.5 kW was found to be on the order of 3 4 mkhour in a fully carbon-lined chamber. A more detailed numerical monte carlo code was also modified to estimate back sputter for a detailed facility and pumping configuration. This code demonstrated similar back sputter rate distributions, but is not yet accurately modeling the magnitudes. The modeling has been benchmarked to recent HERMeS wear testing, using multiple microbalance measurements. These recent measurements have yielded values, on the order of 1.5- 2 microns/khour.

  18. Technology Trend of Sputtering System for Magnetoresistive Devices

    NASA Astrophysics Data System (ADS)

    Tsunekawa, Koji

    Magnetoresistive films used for read-heads of hard disc drives, magnetic random access memory devices, and magnetic sensors are fabricated by magnetron sputtering method. Since giant magnetoresistive and tunnel magnetoresistive films are composed of multilayered films, in which the thickness of each layer is in the nanometer range, high accuracy in thickness control and thickness uniformity is required for the sputtering systems. Film properties are also influenced by the quality of the vacuum during the fabrication process. This article addresses such issues on the deposition of magnetoresistive films, and introduces mass-production sputtering technologies capable of fabricating high quality multilayers. Furthermore, fabrication methods of the tunnel barrier in tunnel magnetoresistive devices are also described.

  19. 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.

  20. Alloying of metal nanoparticles by ion-beam induced sputtering

    NASA Astrophysics Data System (ADS)

    Magudapathy, P.; Srivastava, S. K.; Gangopadhyay, P.; Amirthapandian, S.; Saravanan, K.; Das, A.; Panigrahi, B. K.

    2017-01-01

    Ion-beam sputtering technique has been utilized for controlled synthesis of metal alloy nanoparticles of compositions that can be tuned. Analysis of various experimental results reveals the formation of Ag-Cu alloy nanoparticles on a silica substrate. Surface-plasmon optical resonance positions and observed shifts of Ag Bragg angles in X-ray diffraction pattern particularly confirm formation of alloy nanoparticles on glass samples. Sputtering induced nano-alloying mechanism has been discussed and compared with thermal mixing of Ag and Cu thin films on glass substrates. Compositions and sizes of alloy nanoparticles formed during ion-beam induced sputtering are found to exceed far from the values of thermal mixing.

  1. Anion formation in sputter ion sources by neutral resonant ionization

    SciTech Connect

    Vogel, J. S.

    2016-02-15

    Focused Cs{sup +} beams in sputter ion sources create mm-diameter pits supporting small plasmas that control anionization efficiencies. Sputtering produces overwhelmingly neutral products that the plasma can ionize as in a charge-change vapor. Electron capture between neutral atoms rises as the inverse square of the difference between the ionization potential of the Cs state and the electron affinity of the sputtered atom, allowing resonant ionization at very low energies. A plasma collision-radiation model followed electronic excitation up to Cs(7d). High modeled Cs(7d) in a 0.5 mm recess explains the 80 μA/mm{sup 2} C{sup −} current density compared to the 20 μA/mm{sup 2} from a 1 mm recess.

  2. Sputtering - Its relationship to isotopic fractionation on the lunar surface

    NASA Technical Reports Server (NTRS)

    Kerridge, J. F.; Kaplan, I. R.

    1978-01-01

    Silicon, oxygen, sulfur and, possibly, potassium show systematic enrichment of heavier isotopes with increasing soil maturity, probably as a result of solar-wind sputtering, but such a pattern is not exhibited by solar wind-implanted species. Apparently sputter-erosion is not penetrating to their implantation depth, about 200 A. This suggests that sputtering on the moon is being impeded by deposition of vapor condensate following meteoritic impact. Although neither secular variation in the isotopic composition at the source of regolith carbon, probably the solar wind, nor isotopic fractionation of carbon after implantation in the regolith can be ruled out, carbon isotope systematics currently yield no evidence in support of either process.

  3. Interpretation of sputter depth profiles by mixing simulations.

    PubMed

    Kupris, G; Rössler, H; Ecke, G; Hofmann, S

    1995-10-01

    The interpretation of sputter depth profiles can be simplified by use of computer simulations. Distortions caused by mixing effects and distortions caused by the information depth of the analytical method have to be distinguished. Atomic mixing and the information depth distort the depth profile simultaneously. Therefore, it is necessary to take into consideration a superposition of both distortion effects. The sputtering of a GaAs/A1As multilayer has been calculated on a personal computer with the binary collision approximation code T-DYN by Biersack and with an own layer model. A new computer code LAMBDA has been used for the investigation of the influence of the AES information depth in addition to atomic mixing and preferential sputtering. A comparison of the calculated and the measured depth profile explains the observed effects. Therefore conclusions can be drawn about the original elemental distribution in the sample from the measured depth profile.

  4. Ion beam sputter target and method of manufacture

    DOEpatents

    Higdon, Clifton; Elmoursi, Alaa A.; Goldsmith, Jason; Cook, Bruce; Blau, Peter; Jun, Qu; Milner, Robert

    2014-09-02

    A target for use in an ion beam sputtering apparatus made of at least two target tiles where at least two of the target tiles are made of different chemical compositions and are mounted on a main tile and geometrically arranged on the main tile to yield a desired chemical composition on a sputtered substrate. In an alternate embodiment, the tiles are of varied thickness according to the desired chemical properties of the sputtered film. In yet another alternate embodiment, the target is comprised of plugs pressed in a green state which are disposed in cavities formed in a main tile also formed in a green state and the assembly can then be compacted and then sintered.

  5. Direct measurements of classical and enhanced gradient-aligned cross-field ion flows in a helicon plasma source using laser-induced fluorescence

    SciTech Connect

    Siddiqui, M. Umair Thompson, Derek S.; McIlvain, Julianne M.; Short, Zachary D.; Scime, Earl E.

    2015-12-15

    Direct laser induced fluorescence measurements are shown of cross-field ion flows normal to an absorbing boundary that is aligned parallel to the axial magnetic field in a helicon plasma. We show Langmuir and emissive probe measurements of local density and plasma potential in the same region, as well as floating probe spectra near the boundary. With these measurements, we investigate the influence of ion-neutral collisionality on radial ion transport by varying the ratio of the ion gyro-radius, ρ{sub i}, to the ion-neutral collision length, λ, over the range 0.34 ≤ ρ{sub i}λ{sup −1} ≤ 1.60. Classical drift-diffusion transport along density and potential gradients is sufficient to describe flow profiles for most cases. For two parameter regimes (ρ{sub i}λ{sup −1} = 0.65 and 0.44), low-frequency electrostatic fluctuations (f < 10 kHz) and enhanced cross-field bulk ion flow to the boundary are observed.

  6. Magnetic moment and local magnetic induction of superconducting/ferromagnetic structures subjected to crossed fields: experiments on GdBCO and modelling

    NASA Astrophysics Data System (ADS)

    Fagnard, J. F.; Morita, M.; Nariki, S.; Teshima, H.; Caps, H.; Vanderheyden, B.; Vanderbemden, P.

    2016-12-01

    Recent studies have shown that ferromagnetic materials can be used together with bulk high temperature superconductors in order to improve their magnetic trapped field. Remarkably, it has also been pointed out that ferromagnets can help in reducing the crossed field effect, namely the magnetization decay that is observed under the application of AC transverse magnetic fields. In this work, we pursue a detailed study of the influence of the geometry of the ferromagnetic part on both trapped fields and crossed field effects. The magnetic properties of the hybrid superconducting/soft ferromagnetic structures are characterized by measuring the magnetic moment with a bespoke magnetometer and the local magnetic field density with Hall probes. The results are interpreted by means of 2D and 3D numerical models yielding the distribution of the superconducting currents as a function of the ferromagnet geometry. We examine in details the distortion of the shielding superconducting currents distribution in hybrid structures subjected to crossed magnetic fields. These results confirm the existence of an optimum thickness of the ferromagnet, which depends on the saturation magnetization of the ferromagnetic material and the current density of the superconductor. A hybrid structure providing an efficient protection against the crossed magnetic field while maintaining the magnetic induction along the axis of the structure is suggested. The limitations of the 2D modelling in this configuration are discussed.

  7. Argon Cluster Sputtering Source for ToF-SIMS Depth Profiling of Insulating Materials: High Sputter Rate and Accurate Interfacial Information

    SciTech Connect

    Wang, Zhaoying; Liu, Bingwen; Zhao, Evan; Jin, Ke; Du, Yingge; Neeway, James J.; Ryan, Joseph V.; Hu, Dehong; Zhang, Hongliang; Hong, Mina; Le Guernic, Solenne; Thevuthasan, Suntharampillai; Wang, Fuyi; Zhu, Zihua

    2015-08-01

    For the first time, the use of an argon cluster ion sputtering source has been demonstrated to perform superiorly relative to traditional oxygen and cesium ion sputtering sources for ToF-SIMS depth profiling of insulating materials. The superior performance has been attributed to effective alleviation of surface charging. A simulated nuclear waste glass, SON68, and layered hole-perovskite oxide thin films were selected as model systems due to their fundamental and practical significance. Our study shows that if the size of analysis areas is same, the highest sputter rate of argon cluster sputtering can be 2-3 times faster than the highest sputter rates of oxygen or cesium sputtering. More importantly, high quality data and high sputter rates can be achieved simultaneously for argon cluster sputtering while this is not the case for cesium and oxygen sputtering. Therefore, for deep depth profiling of insulating samples, the measurement efficiency of argon cluster sputtering can be about 6-15 times better than traditional cesium and oxygen sputtering. Moreover, for a SrTiO3/SrCrO3 bi-layer thin film on a SrTiO3 substrate, the true 18O/16O isotopic distribution at the interface is better revealed when using the argon cluster sputtering source. Therefore, the implementation of an argon cluster sputtering source can significantly improve the measurement efficiency of insulating materials, and thus can expand the application of ToF-SIMS to the study of glass corrosion, perovskite oxide thin films, and many other potential systems.

  8. Coating of nanoporous membranes: atomic layer deposition versus sputtering.

    PubMed

    Grigoras, K; Airaksinen, V M; Franssila, S

    2009-06-01

    Nanoporous anodic alumina membranes and silicon samples with plasma etched nanopores have been coated with zinc oxide or gold layer using atomic layer deposition (ALD) or sputtering, respectively. In the case of ALD process, the precursor pulses were extended, compared with planar substrate coating. Thick (60 microm) anodic alumina membranes have been conformally coated with zinc oxide ALD layer. Metal sputtering technique was used just for opposite purpose--to minimize the penetration of gold into the pores during gold-coating of the top and bottom surfaces of the membrane. Scanning electron microscopy (SEM) has been used to investigate the layer thickness, uniformity and conformality inside the nanopores.

  9. Advances in sputtered and ion plated solid film lubrication

    NASA Technical Reports Server (NTRS)

    Spalvins, T.

    1985-01-01

    The glow discharge or ion assisted vacuum deposition techniques, primarily sputtering and ion plating, have rapidly emerged and offer great potential to deposit solid lubricants. The increased energizing of these deposition processes lead to improved adherence and coherence, favorable morphological growth, higher density, and reduced residual stresses in the film. These techniques are of invaluable importance where high precision machines tribo-components require very thin, uniform lubricating films (0.2 m), which do not interface with component tolerances. The performance of sputtered MoS2 films and ion plated Au and Pb films are described in terms of film thickness, coefficient of friction, and wear lives.

  10. Lateral variation of target poisoning during reactive magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Güttler, D.; Grötzschel, R.; Möller, W.

    2007-06-01

    The reactive gas incorporation into a Ti sputter target has been investigated using laterally resolving ion beam analysis during dc magnetron deposition of TiN in an Ar /N2 atmosphere. At sufficiently low reactive gas flow, the nitrogen incorporation exhibits a pronounced lateral variation, with a lower areal density in the target racetrack compared to the target center and edge. The findings are reproduced by model calculations. In the racetrack, the balance of reactive gas injection and sputter erosion is shifted toward erosion. The injection of nitrogen is dominated by combined molecular adsorption and recoil implantation versus direct ion implantation.

  11. 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.

  12. Direct current sputtering of boron from boron/boron mixtures

    DOEpatents

    Timberlake, J.R.; Manos, D.; Nartowitz, E.

    1994-12-13

    A method for coating a substrate with boron by sputtering includes lowering the electrical resistance of a boron-containing rod to allow electrical conduction in the rod; placing the boron-containing rod inside a vacuum chamber containing substrate material to be coated; applying an electrical potential between the boron target material and the vacuum chamber; countering a current avalanche that commences when the conduction heating rate exceeds the cooling rate, and until a steady equilibrium heating current is reached; and, coating the substrate material with boron by sputtering from the boron-containing rod. 2 figures.

  13. Direct current sputtering of boron from boron/coron mixtures

    DOEpatents

    Timberlake, John R.; Manos, Dennis; Nartowitz, Ed

    1994-01-01

    A method for coating a substrate with boron by sputtering includes lowering the electrical resistance of a boron-containing rod to allow electrical conduction in the rod; placing the boron-containing rod inside a vacuum chamber containing substrate material to be coated; applying an electrical potential between the boron target material and the vacuum chamber; countering a current avalanche that commences when the conduction heating rate exceeds the cooling rate, and until a steady equilibrium heating current is reached; and, coating the substrate material with boron by sputtering from the boron-containing rod.

  14. Raman imaging of biofilms using gold sputtered fiber optic probes

    NASA Astrophysics Data System (ADS)

    Christopher, Christina Grace Charlet; Manoharan, Hariharan; Subrahmanyam, Aryasomayajula; Sai, V. V. Raghavendra

    2016-12-01

    In this work we report characterization of bacterial biofilm using gold sputtered optical fiber probe as substrates for confocal Raman spectroscopy measurements. The chemical composition and the heterogeneity of biofilms in the extracellular polymeric substances (EPS) was evaluated. The spatial distribution of bacterial biofilm on the substrates during their growth phase was studied using Raman imaging. Further, the influence of substrate's surface on bacterial adhesion was investigated by studying growth of biofilms on surfaces with hydrophilic and hydrophobic coatings. This study validates the use of gold sputtered optical fiber probes as SERS substrates in confocal microscopic configuration to identify and characterize clinically relevant biofilms.

  15. Cavity-hollow cathode-sputtering source for titanium films

    NASA Astrophysics Data System (ADS)

    Schrittwieser, R.; Ionita, C.; Murawski, A.; Maszl, C.; Asandulesa, M.; Nastuta, A.; Rusu, G.; Douat, C.; Olenici, S. B.; Vojvodic, I.; Dobromir, M.; Luca, D.; Jaksch, S.; Scheier, P.

    2010-08-01

    A cavity-hollow cathode was investigated as low-cost sputtering source for titanium. An argon discharge is produced inside a hollow cathode consisting of two specifically formed disks of titanium. An additional cavity further enhances the pendulum effect of the electrons. Measurements with small Langmuir probes yielded evidence for the formation of a space charge double layer above the cathode. The sputtered atoms form negatively charged clusters. After further acceleration by the double layer the clusters impinge on the substrates. Titanium thin films were produced on highly oriented pyrolytic graphite. The films were investigated by a scanning tunnel microscope and X-ray photoelectron spectroscopy.

  16. Crystallinity of RF-Sputtered MoS2 Films.

    DTIC Science & Technology

    1988-04-15

    RF-Sputtered c MoS2 Films fl 0) J. R. LINCE and PAUL D. FLEISCHAUER Chemistry and Physics Laboratory ’ Laboratory Operations The Aerospace Corporation...block number) The crystallinity and morphology of thin, radio-frequency (rf)-sputtered MoS2 films deposited on 440C stainless steel substrates at both...and 8-20 scans). Under SEM, the films exhibited 4, "ridgelike" (or platelike) formation region for thicknesses between 0.18 and 1.0 m MoS2 . X-ray

  17. Observation of Dust Grain Sputtering in a Shock

    NASA Astrophysics Data System (ADS)

    Raymond, John C.; Ghavamian, P.; Williams, B. J.; Blair, W. P.; Borkowski, K. J.; Gaetz, T. J.; Sankrit, R.

    2014-01-01

    We have detected emission in C IV λλ1548,1551 from C atoms sputtered from dust in the gas behind a shock wave in the Cygnus Loop using COS on HST. The intensity agrees approximately with predictions from model calculations that match the Spitzer 24 μm and the X-ray intensity profiles. Thus these observations confirm the overall picture of dust destruction in SNR shocks and the sputtering rates assumed. However, the CIV intensity 10" behind the shock is too high compared to the intensities at the shock and 25" behind it. Projection effects and a complex geometry are probably responsible for the discrepancy.

  18. 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.

  19. Growth of RuO2 nanorods in reactive sputtering

    NASA Astrophysics Data System (ADS)

    Lin, Yu-Tsun; Chen, Chun-Yu; Hsiung, Chang-Po; Cheng, Kai-Wen; Gan, Jon-Yiew

    2006-08-01

    The synthesis of RuO2 nanorods with reactive sputtering was demonstrated in this work. The synthesis process is very much like the metal organic chemical vapor deposition, except that RuO3 generated with reactive sputtering under high oxygen-to-argon flow ratio (>5SCCM /15SCCM) (SCCM denotes cubic centimeter per minute at STP) and high substrate temperature (>300°C) is used in place of the metal organic precursor. RuO2 nanorods tend to grow steadily with constant aspect ratio (˜27) and the field-emission characteristics appear very sensitive to their spatial distribution.

  20. Switchable diode effect in oxygen vacancy-modulated SrTiO3 single crystal

    NASA Astrophysics Data System (ADS)

    Pan, Xinqiang; Shuai, Yao; Wu, Chuangui; Luo, Wenbo; Sun, Xiangyu; Zeng, Huizhong; Bai, Xiaoyuan; Gong, Chaoguan; Jian, Ke; Zhang, Lu; Guo, Hongliang; Tian, Benlang; Zhang, Wanli

    2017-09-01

    SrTiO3 (STO) single crystal wafer was annealed in vacuum, and co-planar metal-insulator-metal structure of Pt/Ti/STO/Ti/Pt were formed by sputtering Pt/Ti electrodes onto the surface of STO after annealing. The forming-free resistive switching behavior with self-compliance property was observed in the sample. The sample showed switchable diode effect, which is explained by a simple model that redistribution of oxygen vacancies (OVs) under the external electric field results in the formation of n-n+ junction or n+-n junction (n donated n-type semiconductor; n+ donated heavily doped n-type semiconductor). The self-compliance property is also interpreted by the formation of n-n+/n+-n junction caused by the migration of the OVs under the electric field.