Science.gov

Sample records for p-type silicon material

  1. Method of mitigating titanium impurities effects in p-type silicon material for solar cells

    NASA Technical Reports Server (NTRS)

    Salama, A. M. (Inventor)

    1980-01-01

    Microstructural evaluation tests performed on Cu-doped, Ti-doped and Cu/Ti doped p-type silicon single crystal wafers, before and after the solar cell fabrication, and evaluation of both dark forward and reverse I-V characteristic records for the solar cells produced from the corresponding silicon wafers, show that Cu mitigates the unfavorable effects of Ti, and thus provides for higher conversion efficiency, thereby providing an economical way to reduce the deleterious effects of titanium, one of the impurities present in metallurgical grade silicon material.

  2. Value Proposition for High Lifetime (p-type) and Thin Silicon Materials in Solar PV Applications: Preprint

    SciTech Connect

    Goodrich, A.; Woodhouse, M.; Hacke, P.

    2012-06-01

    Most silicon PV road maps forecast a continued reduction in wafer thickness, despite rapid declines in the primary incentive for doing so -- polysilicon feedstock price. Another common feature of most silicon-technology forecasts is the quest for ever-higher device performance at the lowest possible costs. The authors present data from device-performance and manufacturing- and system-installation cost models to quantitatively establish the incentives for manufacturers to pursue advanced (thin) wafer and (high efficiency) cell technologies, in an age of reduced feedstock prices. This analysis exhaustively considers the value proposition for high lifetime (p-type) silicon materials across the entire c-Si PV supply chain.

  3. Irradiation and annealing of p-type silicon carbide

    SciTech Connect

    Lebedev, Alexander A.; Bogdanova, Elena V.; Grigor'eva, Maria V.; Lebedev, Sergey P.; Kozlovski, Vitaly V.

    2014-02-21

    The development of the technology of semiconductor devices based on silicon carbide and the beginning of their industrial manufacture have made increasingly topical studies of the radiation hardness of this material on the one hand and of the proton irradiation to form high-receptivity regions on the other hand. This paper reports on a study of the carrier removal rate (V{sub d}) in p-6H-SiC under irradiation with 8 MeV protons and of the conductivity restoration in radiation- compensated epitaxial layers of various p-type silicon carbide polytypes. V{sub d} was determined by analysis of capacitance-voltage characteristics and from results of Hall effect measurements. It was found that the complete compensation of samples with the initial value of Na - Nd ≈ 1.5 × 10{sup 18} cm{sup −3} occurs at an irradiation dose of ∼1.1 × 10{sup 16} cm{sup −2}. It is shown that specific features of the sublimation layer SiC (compared to CVD layers) are clearly manifested upon the gamma and electron irradiation and are hardly noticeable under the proton and neutron irradiation. It was also found that the radiation-induced compensation of SiC is retained after its annealing at ≤1000°C. The conductivity is almost completely restored at T ≥ 1200°C. This character of annealing of the radiation compensation is independent of a silicon carbide polytype and the starting doping level of the epitaxial layer. The complete annealing temperatures considerably exceed the working temperatures of SiC-based devices. It is shown that the radiation compensation is a promising method in the technology of high-temperature devices based on SiC.

  4. New electron trap in p-type Czochralski silicon

    NASA Technical Reports Server (NTRS)

    Mao, B.-Y.; Lagowski, J.; Gatos, H. C.

    1984-01-01

    A new electron trap (acceptor level) was discovered in p-type Czochralski (CZ) silicon by current transient spectroscopy. The behavior of this trap was found to be similar to that of the oxygen thermal donors; thus, 450 C annealing increases the trap concentration while high-temperature annealing (1100-1200 C) leads to the virtual elimination of the trap. The new trap is not observed in either float-zone or n-type CZ silicon. Its energy level depends on the group III doping element in the sample. These findings suggest that the trap is related to oxygen, and probably to the acceptor impurity as well.

  5. Anodic etching of p-type cubic silicon carbide

    NASA Technical Reports Server (NTRS)

    Harris, G. L.; Fekade, K.; Wongchotigul, K.

    1992-01-01

    p-Type cubic silicon carbide was anodically etched using an electrolyte of HF:HCl:H2O. The etching depth was determined versus time with a fixed current density of 96.4 mA/sq cm. It was found that the etching was very smooth and very uniform. An etch rate of 22.7 nm/s was obtained in a 1:1:50 HF:HCl:H2O electrolyte.

  6. P type porous silicon resistivity and carrier transport

    SciTech Connect

    Ménard, S.; Fèvre, A.; Billoué, J.; Gautier, G.

    2015-09-14

    The resistivity of p type porous silicon (PS) is reported on a wide range of PS physical properties. Al/PS/Si/Al structures were used and a rigorous experimental protocol was followed. The PS porosity (P{sub %}) was found to be the major contributor to the PS resistivity (ρ{sub PS}). ρ{sub PS} increases exponentially with P{sub %}. Values of ρ{sub PS} as high as 1 × 10{sup 9} Ω cm at room temperature were obtained once P{sub %} exceeds 60%. ρ{sub PS} was found to be thermally activated, in particular, when the temperature increases from 30 to 200 °C, a decrease of three decades is observed on ρ{sub PS}. Based on these results, it was also possible to deduce the carrier transport mechanisms in PS. For P{sub %} lower than 45%, the conduction occurs through band tails and deep levels in the tissue surrounding the crystallites. When P{sub %} overpasses 45%, electrons at energy levels close to the Fermi level allow a hopping conduction from crystallite to crystallite to appear. This study confirms the potential of PS as an insulating material for applications such as power electronic devices.

  7. Laser induced lifetime degradation in p-type crystalline silicon

    SciTech Connect

    Ametowobla, M.; Bilger, G.; Koehler, J. R.; Werner, J. H.

    2012-06-01

    Pulsed, green laser irradiation of uncoated p-type silicon leads to a significant reduction of the effective minority carrier lifetime. The reason for the lifetime drop lies in the introduction of recombination centres into the laser melted and recrystallized surface layer, leading to a low local minority carrier lifetime {tau} Almost-Equal-To 10 ns inside this surface layer. The laser treatment introduces the impurities oxygen, carbon and nitrogen into the silicon and further leads to an n-type doping of the surface layer. There are strong indications that these impurities are responsible for the observed n-type doping, as well as the lifetime reduction after irradiation. Both effects are removed by thermal annealing. An estimate shows that the low local lifetime does nevertheless not affect the performance of industrial or contacted selective solar cell emitter structures.

  8. Laser induced lifetime degradation in p-type crystalline silicon

    NASA Astrophysics Data System (ADS)

    Ametowobla, M.; Bilger, G.; Köhler, J. R.; Werner, J. H.

    2012-06-01

    Pulsed, green laser irradiation of uncoated p-type silicon leads to a significant reduction of the effective minority carrier lifetime. The reason for the lifetime drop lies in the introduction of recombination centres into the laser melted and recrystallized surface layer, leading to a low local minority carrier lifetime τ ≈ 10 ns inside this surface layer. The laser treatment introduces the impurities oxygen, carbon and nitrogen into the silicon and further leads to an n-type doping of the surface layer. There are strong indications that these impurities are responsible for the observed n-type doping, as well as the lifetime reduction after irradiation. Both effects are removed by thermal annealing. An estimate shows that the low local lifetime does nevertheless not affect the performance of industrial or contacted selective solar cell emitter structures.

  9. Use of hexamethyldisiloxane for p-type microcrystalline silicon oxycarbide layers

    NASA Astrophysics Data System (ADS)

    Goyal, Prabal; Hong, Junegie; Haddad, Farah; Maurice, Jean-Luc; Cabarrocas, Pere Roca i.; Johnson, Erik

    2016-01-01

    The use of hexamethyldisiloxane (HMDSO) as an oxygen source for the growth of p-type silicon-based layers deposited by Plasma Enhanced Chemical Vapor Deposition is evaluated. The use of this source led to the incorporation of almost equivalent amounts of oxygen and carbon, resulting in microcrystalline silicon oxycarbide thin films. The layers were examined with characterisation techniques including Spectroscopic Ellipsometry, Dark Conductivity, Fourier Transform Infrared Spectroscopy, Secondary Ion Mass Spectrometry and Transmission Electron Microscopy to check material composition and structure. Materials studies show that the refractive indices of the layers can be tuned over the range from 2.5 to 3.85 (measured at 600 nm) and in-plane dark conductivities over the range from 10-8 S/cm to 1 S/cm, suggesting that these doped layers are suitable for solar cell applications. The p-type layers were tested in single junction amorphous silicon p-i-n type solar cells.

  10. Reassessment of the recombination parameters of chromium in n- and p-type crystalline silicon and chromium-boron pairs in p-type crystalline silicon

    SciTech Connect

    Sun, Chang Rougieux, Fiacre E.; Macdonald, Daniel

    2014-06-07

    Injection-dependent lifetime spectroscopy of both n- and p-type, Cr-doped silicon wafers with different doping levels is used to determine the defect parameters of Cr{sub i} and CrB pairs, by simultaneously fitting the measured lifetimes with the Shockley-Read-Hall model. A combined analysis of the two defects with the lifetime data measured on both n- and p-type samples enables a significant tightening of the uncertainty ranges of the parameters. The capture cross section ratios k = σ{sub n}/σ{sub p} of Cr{sub i} and CrB are determined as 3.2 (−0.6, +0) and 5.8 (−3.4, +0.6), respectively. Courtesy of a direct experimental comparison of the recombination activity of chromium in n- and p-type silicon, and as also suggested by modelling results, we conclude that chromium has a greater negative impact on carrier lifetimes in p-type silicon than n-type silicon with similar doping levels.

  11. Dual ohmic contact to N- and P-type silicon carbide

    NASA Technical Reports Server (NTRS)

    Okojie, Robert S. (Inventor)

    2013-01-01

    Simultaneous formation of electrical ohmic contacts to silicon carbide (SiC) semiconductor having donor and acceptor impurities (n- and p-type doping, respectively) is disclosed. The innovation provides for ohmic contacts formed on SiC layers having n- and p-doping at one process step during the fabrication of the semiconductor device. Further, the innovation provides a non-discriminatory, universal ohmic contact to both n- and p-type SiC, enhancing reliability of the specific contact resistivity when operated at temperatures in excess of 600.degree. C.

  12. Novel method of separating macroporous arrays from p-type silicon substrate

    NASA Astrophysics Data System (ADS)

    Bobo, Peng; Fei, Wang; Tao, Liu; Zhenya, Yang; Lianwei, Wang; Fu, Ricky K. Y.; Chu, Paul K.

    2012-04-01

    This paper presents a novel method to fabricate separated macroporous silicon using a single step of photo-assisted electrochemical etching. The method is applied to fabricate silicon microchannel plates in 100 mm p-type silicon wafers, which can be used as electron multipliers and three-dimensional Li-ion microbatteries. Increasing the backside illumination intensity and decreasing the bias simultaneously can generate additional holes during the electrochemical etching which will create lateral etching at the pore tips. In this way the silicon microchannel can be separated from the substrate when the desired depth is reached, then it can be cut into the desired shape by using a laser cutting machine. Also, the mechanism of lateral etching is proposed.

  13. Microhardness studies on thin carbon films grown on P-type, (100) silicon

    NASA Technical Reports Server (NTRS)

    Kolecki, J. C.

    1982-01-01

    A program to grow thin carbon films and investigate their physical and electrical properties is described. Characteristics of films grown by rf sputtering and vacuum arc deposition on p type, (100) silicon wafers are presented. Microhardness data were obtained from both the films and the silicon via the Vickers diamond indentation technique. These data show that the films are always harder than the silicon, even when the films are thin (of the order of 1000 A). Vacuum arc films were found to contain black carbon inclusions of the order of a few microns in size, and clusters of inclusions of the order of tens of microns. Transmission electron diffraction showed that the films being studied were amorphous in structure.

  14. Absence of positronium formation in clean buried nanocavities in p-type silicon

    SciTech Connect

    Brusa, R.S.; Macchi, C.; Mariazzi, S.; Karwasz, G.P.; Egger, W.; Sperr, P.; Koegel, G.

    2005-06-15

    Buried nanocavities at about 350 nm depth in Si were produced by thermal treatment of He implanted p-type (100) Si. The internal surfaces of the nanocavities were found free of impurity decorations by examining the high-momentum part of the Doppler-broadened positron annihilation spectra. Positron lifetime measurements with a pulsed slow positron beam show neither a short lifetime (125-150 ps) ascribable to parapositronium nor a longer lifetime (2-4 ns) ascribable to pick-off annihilation of orthopositronium. The lifetime of positrons trapped into nanocavities was found to be about 500 ps. The absence of positronium formation could be explained by an insufficient electron density and a lack of electron states in the band gap at the nanocavities internal surfaces produced in the p-type silicon.

  15. Numerical simulation of radiation damage effects in p-type silicon detectors

    NASA Astrophysics Data System (ADS)

    Petasecca, M.; Moscatelli, F.; Passeri, D.; Pignatel, G. U.; Scarpello, C.

    2006-07-01

    In the framework of the CERN-RD50 Collaboration, the adoption of p-type substrates has been proposed as a suitable approach to optimize the long-term radiation hardness of silicon detectors. In this work, we present a numerical model for the simulation of radiation damage effects in p-type silicon, developed within the general-purpose device simulator DESSIS. The model includes radiation-induced deep-level recombination centers in the semiconductor band-gap and the Shockley-Read-Hall statistics. In particular, two deep-level defects have been introduced: one located at EC-0.42 eV, corresponding to a single charge state divacancy and a second one located at EC-0.46 eV, corresponding to a single charge state tri-vacancy. For simulation purposes we have considered a simple, two-dimensional test structure, consisting of a single diode of 40 μm width and 300 μm depth, surrounded by a 6 μm wide guard ring. The n+ implant region depth is 1 μm, with donor concentration of ND=10 18 cm -3 implanted on a high-resistivity p-type substrate ( NA=5×10 12 cm -3). The results of simulations adopting the proposed radiation damage model for p-type substrate have been compared with experimental measurements carried out on similar test structures irradiated with neutrons at high fluence. A good agreement with the experimental data has been obtained for the depletion voltage and diode leakage current. The simulated current damage constant (α=3.75×10 -17 A cm -1) is in satisfactory agreement with values reported in the literature. A preliminary study of charge collection efficiency as a function of the fluence is also reported.

  16. Direct Measurement of Electron Beam Induced Currents in p-type Silicon

    SciTech Connect

    Han, M.G.; Zhu, Y.; Sasaki, K.; Kato, T.; Fisher, C.A.J.; Hirayama, T.

    2010-08-01

    A new method for measuring electron beam induced currents (EBICs) in p-type silicon using a transmission electron microscope (TEM) with a high-precision tungsten probe is presented. Current-voltage (I-V) curves obtained under various electron-beam illumination conditions are found to depend strongly on the current density of the incoming electron beam and the relative distance of the beam from the point of probe contact, consistent with a buildup of excess electrons around the contact. This setup provides a new experimental approach for studying minority carrier transport in semiconductors on the nanometer scale.

  17. Accelerated light-induced degradation for detecting copper contamination in p-type silicon

    SciTech Connect

    Inglese, Alessandro Savin, Hele; Lindroos, Jeanette

    2015-08-03

    Copper is a harmful metal impurity that significantly impacts the performance of silicon-based devices if present in active regions. In this contribution, we propose a fast method consisting of simultaneous illumination and annealing for the detection of copper contamination in p-type silicon. Our results show that, within minutes, such method is capable of producing a significant reduction of the minority carrier lifetime. A spatial distribution map of copper contamination can then be obtained through the lifetime values measured before and after degradation. In order to separate the effect of the light-activated copper defects from the other metastable complexes in low resistivity Cz-silicon, we carried out a dark anneal at 200 °C, which is known to fully recover the boron-oxygen defect. Similar to the boron-oxygen behavior, we show that the dark anneal also recovers the copper defects. However, the recovery is only partial and it can be used to identify the possible presence of copper contamination.

  18. Accelerated light-induced degradation for detecting copper contamination in p-type silicon

    NASA Astrophysics Data System (ADS)

    Inglese, Alessandro; Lindroos, Jeanette; Savin, Hele

    2015-08-01

    Copper is a harmful metal impurity that significantly impacts the performance of silicon-based devices if present in active regions. In this contribution, we propose a fast method consisting of simultaneous illumination and annealing for the detection of copper contamination in p-type silicon. Our results show that, within minutes, such method is capable of producing a significant reduction of the minority carrier lifetime. A spatial distribution map of copper contamination can then be obtained through the lifetime values measured before and after degradation. In order to separate the effect of the light-activated copper defects from the other metastable complexes in low resistivity Cz-silicon, we carried out a dark anneal at 200 °C, which is known to fully recover the boron-oxygen defect. Similar to the boron-oxygen behavior, we show that the dark anneal also recovers the copper defects. However, the recovery is only partial and it can be used to identify the possible presence of copper contamination.

  19. Fabrication of p-type porous silicon nanowire with oxidized silicon substrate through one-step MACE

    SciTech Connect

    Li, Shaoyuan; Ma, Wenhui; Zhou, Yang; Chen, Xiuhua; Xiao, Yongyin; Ma, Mingyu; Wei, Feng; Yang, Xi

    2014-05-01

    In this paper, the simple pre-oxidization process is firstly used to treat the starting silicon wafer, and then MPSiNWs are successfully fabricated from the moderately doped wafer by one-step MACE technology in HF/AgNO{sub 3} system. The PL spectrum of MPSiNWs obtained from the oxidized silicon wafers show a large blue-shift, which can be attributed to the deep Q. C. effect induced by numerous mesoporous structures. The effects of HF and AgNO{sub 3} concentration on formation of SiNWs were carefully investigated. The results indicate that the higher HF concentration is favorable to the growth of SiNWs, and the density of SiNWs is significantly reduced when Ag{sup +} ions concentrations are too high. The deposition behaviors of Ag{sup +} ions on oxidized and unoxidized silicon surface were studied. According to the experimental results, a model was proposed to explain the formation mechanism of porous SiNWs by etching the oxidized starting silicon. - Graphical abstract: Schematic cross-sectional views of PSiNWs array formation by etching oxidized silicon wafer in HF/AgNO{sub 3} solution. (A) At the starting point; (B) during the etching process; and (C) after Ag dendrites remove. - Highlights: • Prior to etching, a simple pre-oxidation is firstly used to treat silicon substrate. • The medially doped p-type MPSiNWs are prepared by one-step MACE. • Deposition behaviors of Ag{sup +} ions on oxidized and unoxidized silicon are studied. • A model is finally proposed to explain the formation mechanism of PSiNWs.

  20. Percolation network in resistive switching devices with the structure of silver/amorphous silicon/p-type silicon

    SciTech Connect

    Liu, Yanhong; Gao, Ping; Bi, Kaifeng; Peng, Wei; Jiang, Xuening; Xu, Hongxia

    2014-01-27

    Conducting pathway of percolation network was identified in resistive switching devices (RSDs) with the structure of silver/amorphous silicon/p-type silicon (Ag/a-Si/p-Si) based on its gradual RESET-process and the stochastic complex impedance spectroscopy characteristics (CIS). The formation of the percolation network is attributed to amounts of nanocrystalline Si particles as well as defect sites embedded in a-Si layer, in which the defect sites supply positions for Ag ions to nucleate and grow. The similar percolation network has been only observed in Ag-Ge-Se based RSD before. This report provides a better understanding for electric properties of RSD based on the percolation network.

  1. Characterization of irradiated detectors fabricated on p-type silicon substrates for super-LHC

    NASA Astrophysics Data System (ADS)

    Miñano, M.; Campabadal, F.; Escobar, C.; García, C.; González, S.; Lacasta, C.; Lozano, M.; Martí i García, S.; Pellegrini, G.; Rafí, J. M.; Ullán, M.

    2007-12-01

    An upgrade of the large hadron collider (LHC), the Super-LHC (SLHC), towards higher luminosities is currently being discussed as an extension of the LHC physics program. The goal of the SLHC is to operate at a luminosity of 10 35 cm -2 s -1 (10 times larger than that of the LHC one). Thus, the operation of the SLHC implies a need to upgrade the detectors of the LHC experiments. The current tracking system of ATLAS will not cope with that luminosity. New solutions must be investigated to improve the radiation tolerance of the semiconductor detector. p-Type bulk sensors are being considered for the ATLAS tracking system for the SLHC. Microstrip detectors fabricated by CNM-IMB on p-type high-resistivity float zone silicon have been irradiated with neutrons at the TRIGA Mark II reactor in Ljubljana up to a fluence of 10 16 cm -2 (as expected in the innermost region of the ATLAS upgrade) and have been characterized at IFIC Laboratory. The collected charge, after irradiation, has been measured by infrared laser illumination. The leakage current of those sensors is also reported.

  2. Effective lifetimes exceeding 300 μs in gettered p-type epitaxial kerfless silicon for photovoltaics

    NASA Astrophysics Data System (ADS)

    Powell, D. M.; Hofstetter, J.; Fenning, D. P.; Hao, R.; Ravi, T. S.; Buonassisi, T.

    2013-12-01

    We evaluate defect concentrations and investigate the lifetime potential of p-type single-crystal kerfless silicon produced via epitaxy for photovoltaics. In gettered material, low interstitial iron concentrations (as low as (3.2 ± 2.2) × 109 cm-3) suggest that minority-carrier lifetime is not limited by dissolved iron. An increase in gettered lifetime from <20 to >300 μs is observed after increasing growth cleanliness. This improvement coincides with reductions in the concentration of Mo, V, Nb, and Cr impurities, but negligible change in the low area-fraction (<5%) of dislocated regions. Device simulations indicate that the high bulk lifetime of this material could support solar cell efficiencies >23%.

  3. Evidence for an iron-hydrogen complex in p-type silicon

    SciTech Connect

    Leonard, S. Markevich, V. P.; Peaker, A. R.; Hamilton, B.; Murphy, J. D.

    2015-07-20

    Interactions of hydrogen with iron have been studied in Fe contaminated p-type Czochralski silicon using capacitance-voltage profiling and deep level transient spectroscopy (DLTS). Hydrogen has been introduced into the samples from a silicon nitride layer grown by plasma enhanced chemical vapor deposition. After annealing of the Schottky diodes on Si:Fe + H samples under reverse bias in the temperature range of 90–120 °C, a trap has been observed in the DLTS spectra which we have assigned to a Fe-H complex. The trap is only observed when a high concentration of hydrogen is present in the near surface region. The trap concentration is higher in samples with a higher concentration of single interstitial Fe atoms. The defect has a deep donor level at E{sub v} + 0.31 eV. Direct measurements of capture cross section of holes have shown that the capture cross section is not temperature dependent and its value is 5.2 × 10{sup −17} cm{sup 2}. It is found from an isochronal annealing study that the Fe-H complex is not very stable and can be eliminated completely by annealing for 30 min at 125 °C.

  4. Evidence for an iron-hydrogen complex in p-type silicon

    NASA Astrophysics Data System (ADS)

    Leonard, S.; Markevich, V. P.; Peaker, A. R.; Hamilton, B.; Murphy, J. D.

    2015-07-01

    Interactions of hydrogen with iron have been studied in Fe contaminated p-type Czochralski silicon using capacitance-voltage profiling and deep level transient spectroscopy (DLTS). Hydrogen has been introduced into the samples from a silicon nitride layer grown by plasma enhanced chemical vapor deposition. After annealing of the Schottky diodes on Si:Fe + H samples under reverse bias in the temperature range of 90-120 °C, a trap has been observed in the DLTS spectra which we have assigned to a Fe-H complex. The trap is only observed when a high concentration of hydrogen is present in the near surface region. The trap concentration is higher in samples with a higher concentration of single interstitial Fe atoms. The defect has a deep donor level at Ev + 0.31 eV. Direct measurements of capture cross section of holes have shown that the capture cross section is not temperature dependent and its value is 5.2 × 10-17 cm2. It is found from an isochronal annealing study that the Fe-H complex is not very stable and can be eliminated completely by annealing for 30 min at 125 °C.

  5. P-stop isolation study of irradiated n-in-p type silicon strip sensors for harsh radiation environments

    NASA Astrophysics Data System (ADS)

    Printz, Martin

    2016-09-01

    In order to determine the most radiation hard silicon sensors for the CMS Experiment after the Phase II Upgrade in 2023 a comprehensive study of silicon sensors after a fluence of up to 1.5 ×1015neq /cm2 corresponding to 3000fb-1 after the HL-LHC era has been carried out. The results led to the decision that the future Outer Tracker (20 cm < R < 110 cm) of CMS will consist of n-in-p type sensors. This technology is more radiation hard but also the manufacturing is more challenging compared to p-in-n type sensors due to additional process steps in order to suppress the accumulation of electrons between the readout strips. One possible isolation technique of adjacent strips is the p-stop structure which is a p-type material implantation with a certain pattern for each individual strip. However, electrical breakdown and charge collection studies indicate that the process parameters of the p-stop structure have to be carefully calibrated in order to achieve a sufficient strip isolation but simultaneously high breakdown voltages. Therefore a study of the isolation characteristics with four different silicon sensor manufacturers has been executed in order to determine the most suitable p-stop parameters for the harsh radiation environment during HL-LHC. Several p-stop doping concentrations, doping depths and different p-stop pattern have been realized and experiments before and after irradiation with protons and neutrons have been performed and compared to T-CAD simulation studies with Synopsys Sentaurus. The measurements combine the electrical characteristics measured with a semi-automatic probestation with Sr90 signal measurements and analogue readout. Furthermore, some samples have been investigated with the help of a cosmic telescope with high resolution allowing charge collection studies of MIPs penetrating the sensor between two strips.

  6. Resistivity dependence of minority carrier lifetime and cell performance in p-type dendritic web silicon ribbon

    NASA Astrophysics Data System (ADS)

    Hilali, Mohamed; Ebong, Abasifreke; Rohatgi, Ajeet; Meier, Daniel L.

    2001-12-01

    This study shows that the bulk lifetime in 95 μm thick p-type dendritic web silicon solar cells is a strong function of bulk resistivity. The higher the resistivity, the greater the bulk lifetime. This behavior is explained on the basis of dopant-defect interaction, which increases the lifetime limiting trap concentration with the addition of dopant atoms. Model calculations show that in the absence of doping dependence of bulk lifetime ( τ), ˜2 Ω cm web should give the best cell efficiency for bulk lifetimes below 30 μs. However, strong doping dependence of bulk lifetime in p-web cells shifts the optimum resistivity from 2 to 15 Ω cm. Bulk lifetime in the as-grown web material was found to be less than 1 μs for all the resistivities. After the cell processing which involves phosphorus gettering, aluminum gettering, and SiN induced hydrogen passivation of defects, the bulk lifetime increased to 6.68, 11, 31 and 68.9 μs in 0.62, 1.37, 6.45 and 15 Ω cm p-type web material, respectively. Therefore, cell process induced recovery of lifetime in web is doping dependent, which favors high resistivity. Solar cells fabricated on 95 μm thick web silicon by a manufacturable process involving screen-printing and belt-line processing gave 14.5% efficient 4 cm 2 cells on 15 Ω cm resistivity. This represents a record efficiency for such a thin manufacturable screen-printed cell on a low-cost PV grade Si ribbon that requires no wafering or etching.

  7. Analytical approximation of effective surface recombination velocity of dielectric-passivated p-type silicon

    NASA Astrophysics Data System (ADS)

    Brody, Jed; Rohatgi, Ajeet

    2001-09-01

    New analytical equations are derived to approximate the effective surface recombination velocity ( Seff) on p-type silicon for three different cases: low-level injection (LLI) with surface hole concentration ( ps) much greater than surface electron concentration ( ns) and with silicon charge ( QSi) due primarily to ionized acceptors, LLI with ns≫ ps and QSi due primarily to ionized acceptors, and high-level injection with ns≫ ps and QSi due primarily to mobile electrons. The three new equations predict the dependence of Seff on individual parameters such as injection level ( Δn), doping level ( NA), and fixed dielectric charge ( Qf). The new equations complement a previously derived result (for LLI with ns≫ ps and QSi due primarily to mobile electrons) and together allow reasonable explanations to be given for all sections of all Seff vs. Δn and Seff vs. NA curves generated by a quasi-exact numerical method. The analytical approximations are compared with the full numerical solutions. Under appropriate conditions, the analytical approximations agree with the numerical solutions within a factor of 3. Guided by the analytical approximations, numerical solutions are fitted to two sets of experimental data: the injection level dependence of Seff for an oxide-passivated wafer; and the doping dependence of Seff for wafers passivated by plasma-enhanced chemical vapor deposited nitride (SiN x), conventional furnace oxide (CFO), and the SiN x/CFO stack. The SiN x/CFO stack not only provides surface passivation that is superior to either dielectric alone; it is also less doping dependent. The analytical approximations indicate that this suppressed doping dependence could be due to a lower interface state density or a higher fixed dielectric charge ( Qf).

  8. Copper-related deep-level centers in irradiated p-type silicon

    SciTech Connect

    Yarykin, Nikolai; Weber, Joerg

    2011-03-15

    Deep-level centers are investigated in the p-type Si on copper-contaminated samples which were also electron irradiated. Standard and Laplace-transform deep-level transient spectroscopy techniques were employed to characterize the samples. Several Cu-related centers are observed to form either as a result of the low-temperature Cu diffusion into the irradiated crystals or due to irradiation of the Cu-contaminated samples and subsequent annealing up to 400 deg. C. In all crystals, two Cu-related defects are found to be the most abundant; each of them possesses a pair of levels in the lower half of the gap. The Arrhenius signatures for one pair are measured to be practically identical to those for the donor and acceptor levels of substitutional copper Cu{sub s}, respectively, the levels of other defect being only barely different from the Cu{sub s} levels. Analysis of the introduction rates and depth profiles of the deep-level centers points to the vacancy-oxygen complex (VO, the A center) as the precursor of the most abundant Cu-related defects. It is inferred that Cu{sub s} is formed in irradiated silicon due to interaction with the VO centers via the rather stable intermediate CuVO complex.

  9. High performance p-type thermoelectric materials and methods of preparation

    NASA Technical Reports Server (NTRS)

    Caillat, Thierry (Inventor); Borshchevsky, Alexander (Inventor); Fleurial, Jean-Pierre (Inventor)

    2005-01-01

    The present invention is embodied in high performance p-type thermoelectric materials having enhanced thermoelectric properties and the methods of preparing such materials. In one aspect of the invention, p-type semiconductors of formula Zn4-xAxSb3-yBy wherein 0?x?4, A is a transition metal, B is a pnicogen, and 0?y?3 are formed for use in manufacturing thermoelectric devices with substantially enhanced operating characteristics and improved efficiency. Two methods of preparing p-type Zn4Sb3 and related alloys of the present invention include a crystal growth method and a powder metallurgy method.

  10. Silicone azide fireproof material

    NASA Technical Reports Server (NTRS)

    1978-01-01

    Finely powdered titanium oxide was added to silicone azide as the sintering agent to produce a nonflammable material. Mixing proportions, physical properties, and chemical composition of the fireproofing material are included.

  11. Recent Developments in p-Type Oxide Semiconductor Materials and Devices.

    PubMed

    Wang, Zhenwei; Nayak, Pradipta K; Caraveo-Frescas, Jesus A; Alshareef, Husam N

    2016-05-01

    The development of transparent p-type oxide semiconductors with good performance may be a true enabler for a variety of applications where transparency, power efficiency, and greater circuit complexity are needed. Such applications include transparent electronics, displays, sensors, photovoltaics, memristors, and electrochromics. Hence, here, recent developments in materials and devices based on p-type oxide semiconductors are reviewed, including ternary Cu-bearing oxides, binary copper oxides, tin monoxide, spinel oxides, and nickel oxides. The crystal and electronic structures of these materials are discussed, along with approaches to enhance valence-band dispersion to reduce effective mass and increase mobility. Strategies to reduce interfacial defects, off-state current, and material instability are suggested. Furthermore, it is shown that promising progress has been made in the performance of various types of devices based on p-type oxides. Several innovative approaches exist to fabricate transparent complementary metal oxide semiconductor (CMOS) devices, including novel device fabrication schemes and utilization of surface chemistry effects, resulting in good inverter gains. However, despite recent developments, p-type oxides still lag in performance behind their n-type counterparts, which have entered volume production in the display market. Recent successes along with the hurdles that stand in the way of commercial success of p-type oxide semiconductors are presented. PMID:26879813

  12. Recent Developments in p-Type Oxide Semiconductor Materials and Devices.

    PubMed

    Wang, Zhenwei; Nayak, Pradipta K; Caraveo-Frescas, Jesus A; Alshareef, Husam N

    2016-05-01

    The development of transparent p-type oxide semiconductors with good performance may be a true enabler for a variety of applications where transparency, power efficiency, and greater circuit complexity are needed. Such applications include transparent electronics, displays, sensors, photovoltaics, memristors, and electrochromics. Hence, here, recent developments in materials and devices based on p-type oxide semiconductors are reviewed, including ternary Cu-bearing oxides, binary copper oxides, tin monoxide, spinel oxides, and nickel oxides. The crystal and electronic structures of these materials are discussed, along with approaches to enhance valence-band dispersion to reduce effective mass and increase mobility. Strategies to reduce interfacial defects, off-state current, and material instability are suggested. Furthermore, it is shown that promising progress has been made in the performance of various types of devices based on p-type oxides. Several innovative approaches exist to fabricate transparent complementary metal oxide semiconductor (CMOS) devices, including novel device fabrication schemes and utilization of surface chemistry effects, resulting in good inverter gains. However, despite recent developments, p-type oxides still lag in performance behind their n-type counterparts, which have entered volume production in the display market. Recent successes along with the hurdles that stand in the way of commercial success of p-type oxide semiconductors are presented.

  13. High performance P-type thermoelectric materials and methods of preparation

    NASA Technical Reports Server (NTRS)

    Caillat, Thierry (Inventor); Borshchevsky, Alexander (Inventor); Fleurial, Jean-Pierre (Inventor)

    2002-01-01

    The present invention is embodied in high performance p-type thermoelectric materials having enhanced thermoelectric properties and the methods of preparing such materials. In one aspect of the invention, p-type semiconductors of formula Zn.sub.4-x A.sub.x Sb.sub.3-y B.sub.y wherein 0.ltoreq.x.ltoreq.4, A is a transition metal, B is a pnicogen, and 0.ltoreq.y.ltoreq.3 are formed for use in manufacturing thermoelectric devices with substantially enhanced operating characteristics and improved efficiency. Two methods of preparing p-type Zn.sub.4 Sb.sub.3 and related alloys of the present invention include a crystal growth method and a powder metallurgy method.

  14. Surface States and Effective Surface Area on Photoluminescent P-Type Porous Silicon

    NASA Technical Reports Server (NTRS)

    Weisz, S. Z.; Porras, A. Ramirez; Resto, O.; Goldstein, Y.; Many, A.; Savir, E.

    1997-01-01

    The present study is motivated by the possibility of utilizing porous silicon for spectral sensors. Pulse measurements on the porous-Si/electrolyte system are employed to determine the surface effective area and the surface-state density at various stages of the anodization process used to produce the porous material. Such measurements were combined with studies of the photoluminescence spectra. These spectra were found to shift progressively to the blue as a function of anodization time. The luminescence intensity increases initially with anodization time, reaches a maximum and then decreases with further anodization. The surface state density, on the other hand, increases with anodization time from an initial value of about 2 x 10(exp 12)/sq cm surface to about 1013 sq cm for the anodized surface. This value is attained already after -2 min anodization and upon further anodization remains fairly constant. In parallel, the effective surface area increases by a factor of 10-30. This behavior is markedly different from the one observed previously for n-type porous Si.

  15. Evaluation of Seebeck coefficients in n- and p-type silicon nanowires fabricated by complementary metal-oxide-semiconductor technology.

    PubMed

    Hyun, Younghoon; Park, Youngsam; Choi, Wonchul; Kim, Jaehyeon; Zyung, Taehyoung; Jang, Moongyu

    2012-10-12

    Silicon-based thermoelectric nanowires were fabricated by using complementary metal-oxide-semiconductor (CMOS) technology. 50 nm width n- and p-type silicon nanowires (SiNWs) were manufactured using a conventional photolithography method on 8 inch silicon wafer. For the evaluation of the Seebeck coefficients of the silicon nanowires, heater and temperature sensor embedded test patterns were fabricated. Moreover, for the elimination of electrical and thermal contact resistance issues, the SiNWs, heater and temperature sensors were fabricated monolithically using a CMOS process. For validation of the temperature measurement by an electrical method, scanning thermal microscopy analysis was carried out. The highest Seebeck coefficients were - 169.97 μV K(-1) and 152.82 μV K(-1) and the highest power factors were 2.77 mW m(-1) K(-2) and 0.65 mW m(-1) K(-2) for n- and p-type SiNWs, respectively, in the temperature range from 200 to 300 K. The larger power factor value for n-type SiNW was due to the higher electrical conductivity. The total Seebeck coefficient and total power factor for the n- and p-leg unit device were 157.66 μV K(-1) and 9.30 mW m(-1) K(-2) at 300 K, respectively.

  16. Low resistance Ohmic contact to p-type crystalline silicon via nitrogen-doped copper oxide films

    NASA Astrophysics Data System (ADS)

    Zhang, Xinyu; Wan, Yimao; Bullock, James; Allen, Thomas; Cuevas, Andres

    2016-08-01

    This work explores the application of transparent nitrogen doped copper oxide (CuOx:N) films deposited by reactive sputtering to create hole-selective contacts for p-type crystalline silicon (c-Si) solar cells. It is found that CuOx:N sputtered directly onto crystalline silicon is able to form an Ohmic contact. X-ray photoelectron spectroscopy and Raman spectroscopy measurements are used to characterise the structural and physical properties of the CuOx:N films. Both the oxygen flow rate and the substrate temperature during deposition have a significant impact on the film composition, as well as on the resulting contact resistivity. After optimization, a low contact resistivity of ˜10 mΩ cm2 has been established. This result offers significant advantages over conventional contact structures in terms of carrier transport and device fabrication.

  17. Investigation of surface passivation schemes for p-type monocrystalline silicon solar cell

    NASA Astrophysics Data System (ADS)

    Rahman, Md. Momtazur; Udoy, Ariful Banna

    2016-10-01

    This paper represents an experiment to analyze the dark saturation current densities of passivated surfaces for monocrystalline silicon solar cells. The samples are diffused at peak temperatures of 800-950 °C. Basically, symmetrical lifetime samples with different doping profiles are prepared with alkaline textured and saw damage etched (planar) surfaces. After POCl3 diffusion, the phosphorous silicate glass layers are removed in a wet chemical etching step. Several designs are chosen for the determination of the sheet resistance ( R sh), the concentration profile for excess charge carrier and the minority carrier effective lifetime of the diffused surfaces. The dark saturation current densities ( J o ) and the doping profiles are determined accordingly via quasi-steady state photoconductance decay measurement and electrochemical capacitance-voltage measurement. Three different passivation schemes are investigated as follows: silicon nitride (SiN x ) deposited by plasma-enhanced chemical vapor deposition (PECVD) technique, silicon-rich oxynitride (SiriO x N y ) capped with a PECVD SiN x layer, and thin thermally grown oxide, capped with a PECVD SiN x layer.

  18. Temperature Dependent Tensile Fracture Stress of n- and p-Type Filled-Skutterudite Materials

    SciTech Connect

    Salvador, James R.; Yang, Jihui; Wereszczak, Andrew A; Wang, Hsin; Cho, Jung Y

    2011-01-01

    While materials with excellent thermoelectric performance are most desirable for higher heat to electrical energy conversion efficiency, thermoelectric materials must also be sufficiently mechanically robust to withstand the large number of thermal cycles and vibrational stresses likely to be encountered while in service, particularly in automotive applications. Further these TE materials should be composed of non-toxic and naturally abundant constituent elements and be available as both n- and p-type varieties. Skutterudite based thermoelectric materials seemingly fit this list of criteria. In this contribution we report on the synthesis, tensile fracture strengths, low temperature electrical and thermal transport properties, and coefficients of thermal expansion (CTE), of the n-type skutterudite La{sub 0.05({+-}0.01)}Ba{sub 0.07({+-}0.04)}Yb{sub 0.08({+-}0.02)}Co{sub 4.00({+-}0.01)}Sb{sub 12.02({+-}0.03)} and the p-type Ce{sub 0.30({+-}0.02)}Co{sub 2.57({+-}0.02)}Fe{sub 1.43({+-}0.02)}Sb{sub 11.98({+-}0.03)}. Both materials have tensile fracture strengths that are temperature independent up to 500 C, and are in the range of {approx}140 MPa as measured by a three point bend flexure test fixture described herein. The CTE's were measured by dual rod dilatometry and were determined to be 10.3 ppm/C for the n-type material and 11.5 ppm/C for p-type up to 450 C.

  19. Transformation of divacancies to divacancy-oxygen pairs in p-type Czochralski-silicon; mechanism of divacancy diffusion

    SciTech Connect

    Ganagona, N. Vines, L.; Monakhov, E. V.; Svensson, B. G.

    2014-01-21

    In this work, a comprehensive study on the transition of divacancy (V{sub 2}) to divacancy-oxygen (V{sub 2}O) pairs in p-type silicon has been performed with deep level transient spectroscopy (DLTS). Czochralski grown, boron doped p-type, silicon samples, with a doping concentration of 2 × 10{sup 15} cm{sup −3} and oxygen content of 7.0 ± 1.5 × 10{sup 17} cm{sup −3}, have been irradiated with 1.8 MeV protons. Isothermal annealing at temperatures in the range of 200 °C–300 °C shows a close to one-to-one correlation between the loss in the donor state of V{sub 2} and the formation of the donor state of V{sub 2}O, located at 0.23 eV above the valence band edge. A concurrent transition takes place between the single acceptor states of V{sub 2} and V{sub 2}O, as unveiled by injection of electrons through optical excitation during the trap filling sequence of the DLTS measurements. Applying the theory for diffusion limited reactions, the diffusivity of V{sub 2} in the studied p-type samples is determined to be (1.5 ± 0.7) × 10{sup −3}exp[−(1.31 ± 0.03) eV/kT] cm{sup 2}/s, and this represents the neutral charge state of V{sub 2}. Further, the data seem to favor a two-stage diffusion mechanism involving partial dissociation of V{sub 2}, although a one-stage process cannot be fully excluded.

  20. Silicon dendritic web material

    NASA Technical Reports Server (NTRS)

    Meier, D. L.; Campbell, R. B.; Sienkiewicz, L. J.; Rai-Choudhury, P.

    1982-01-01

    The development of a low cost and reliable contact system for solar cells and the fabrication of several solar cell modules using ultrasonic bonding for the interconnection of cells and ethylene vinyl acetate as the potting material for module encapsulation are examined. The cells in the modules were made from dendritic web silicon. To reduce cost, the electroplated layer of silver was replaced with an electroplated layer of copper. The modules that were fabricated used the evaporated Ti, Pd, Ag and electroplated Cu (TiPdAg/Cu) system. Adherence of Ni to Si is improved if a nickel silicide can be formed by heat treatment. The effectiveness of Ni as a diffusion barrier to Cu and the ease with which nickel silicide is formed is discussed. The fabrication of three modules using dendritic web silicon and employing ultrasonic bonding for interconnecting calls and ethylene vinyl acetate as the potting material is examined.

  1. Simultaneous iron gettering and passivation of p-type monocrystalline silicon using a negatively charged aluminum-doped dielectric

    NASA Astrophysics Data System (ADS)

    Das, Arnab; Rohatgi, Ajeet

    2012-12-01

    Rapid gettering of iron from p-type c-Si has been achieved using a negatively charged spin-on Al-doped glass. After a 10 min oxidation to cure the Al-doped glass, >99% of Fe can be gettered from silicon wafers. This is comparable to, and under some processing conditions better than, the efficiency of conventional POCl3 gettering. In the same short oxidation step, the Al-doped glass also passivates p-Si surfaces with surface recombination velocities of 100 cm/s and 10 600 cm/s achieved for surface doping of 6 × 1015 cm-3 and 4 × 1019 cm-3, respectively. These passivation results are comparable to those achieved with thermal SiO2 layers.

  2. Silicon material task review

    NASA Technical Reports Server (NTRS)

    Lorenz, J. H.

    1986-01-01

    The objectives of the Flat-plate Solar Array (FSA) Project Silicon Material Task are to evaluate technologies, new and old; to develop the most promising technologies; to establish practicality of the processes to meet production, energy use, and economic criteria; and to develop an information base on impurities in polysilicon and to determine their effects on solar cell performance. The approach involves determining process feasibility, setting milestones for the forced selection of the processes, and establishing the technical readiness of the integrated process.

  3. Silicon material technology status

    NASA Astrophysics Data System (ADS)

    Lutwack, R.

    Silicon has been the basic element for the electronic and photovoltaic industries. The use of silicon as the primary element for terrestrial photovoltaic solar arrays is projected to continue. The reasons for this projection are related to the maturity of silicon technology, the ready availability of extremely pure silicon, the performance of silicon solar cells, and the considerable present investment in technology and manufacturing facilities. The technologies for producing semiconductor grade silicon and, to a lesser extent, refined metallurgical grade silicon are considered. It is pointed out that nearly all of the semiconductor grade silicon is produced by processes based on the Siemens deposition reactor, a technology developed 26 years ago. The state-of-the-art for producing silicon by this process is discussed. It is expected that efforts to reduce polysilicon process costs will continue.

  4. Study of nanoparticles TiO2 thin films on p-type silicon substrate using different alcoholic solvents

    NASA Astrophysics Data System (ADS)

    Muaz, A. K. M.; Hashim, U.; Arshad, M. K. Md.; Ruslinda, A. R.; Ayub, R. M.; Gopinath, Subash C. B.; Voon, C. H.; Liu, Wei-Wen; Foo, K. L.

    2016-07-01

    In this paper, sol-gel method spin coating technique is adopted to prepare nanoparticles titanium dioxide (TiO2) thin films. The prepared TiO2 sol was synthesized using titanium butoxide act as a precursor and subjected to deposited on the p-type silicon oxide (p-SiO2) and glass slide substrates under room temperature. The effect of different alcoholic solvents of methanol and ethanol on the structural, morphological, optical and electrical properties were systematically investigated. The coated TiO2 thin films were annealed in furnace at 773 K for 1 h. The structural properties of the TiO2 films were examined with X-ray Diffraction (XRD). From the XRD analysis, both solvents showing good crystallinity with anatase phase were the predominant structure. Atomic Force Microscopy (AFM) was employed to study the morphological of the thin films. The optical properties were investigated by Ultraviolet-visible (UV-Vis) spectroscopy were found that ethanol as a solvent give a higher optical transmittance if compare to the methanol solvent. The electrical properties of the nanoparticles TiO2 thin films were measured using two-point-probe technique.

  5. First-principles prediction of a promising p-type transparent conductive material CsGeCl3

    NASA Astrophysics Data System (ADS)

    Huang, Dan; Zhao, Yu-Jun; Ju, Zhi-Ping; Gan, Li-Yong; Chen, Xin-Man; Li, Chang-Sheng; Yao, Chun-mei; Guo, Jin

    2014-04-01

    Most reported p-type transparent conductive materials are Cu-based compounds such as CuAlO2 and CuCrO2. Here, we report that compounds based on ns2 cations with low binding energy can also possess high valence band maximum, which is crucial for the p-type doping according to the doping limit rules. In particular, CsGeCl3, a compound with valence band maximum from ns2 cations, is predicted as a promising p-type transparent conductive material by first-principles calculations. Our results show that the p-type defect Ge vacancy dominates its intrinsic defects with a shallow transition level, and the calculated hole effective masses are low in CsGeCl3.

  6. Effects of trap-assisted tunneling on gate-induced drain leakage in silicon-germanium channel p-type FET for scaled supply voltages

    NASA Astrophysics Data System (ADS)

    Tiwari, Vishal A.; Divakaruni, Rama; Hook, Terence B.; Nair, Deleep R.

    2016-04-01

    Silicon-germanium is considered as an alternative channel material to silicon p-type FET (pFET) for the development of energy efficient high performance transistors for 28 nm and beyond in a high-k metal gate technology because of its lower threshold voltage and higher mobility. However, gate-induced drain leakage (GIDL) is a concern for high threshold voltage device design because of tunneling at reduced bandgap. In this work, the trap-assisted tunneling and band-to-band tunneling (BTBT) effects on GIDL is analyzed and modeled for SiGe pFETs. Experimental results and Monte Carlo simulation results reveal that the pre-halo germanium pre-amorphization implant used to contain the short channel effects contribute to GIDL at the drain sidewall in addition to GIDL due to BTBT in SiGe devices. The results are validated by comparing the experimental observations with the numerical simulation and a set of calibrated models are used to describe the GIDL mechanisms for various drain and gate bias.

  7. n-p Type variation in thermoelectric AlMgB14-based materials by raw material mixture ratio

    NASA Astrophysics Data System (ADS)

    Fujima, Takuya; Arimatsu, Hideki; Miura, Shota; Yokoyama, Shun; Takagi, Ken-ichi

    2015-09-01

    We controlled the sign of Seebeck coefficient of AlMgB14-based thermoelectric materials by changing the raw material ratio for spark plasma sintering. The raw material powders of Al, Mg and B were mixed by V-shape mixer then sintered at 1773 K. Some sintered samples exhibited negative Seebeck coefficients and the others did positive as established for stoichiometric AlMgB14. The temperature dependence of electrical conductivity was different from each other type. Rietveld refinement for XRD results about the samples revealed that Mg site in the AlMgB14-lattice was occupied more for negative materials than the p-type ones and the negative samples had more valence electron than the other.

  8. Process for forming pure silver ohmic contacts to N- and P-type gallium arsenide materials

    DOEpatents

    Hogan, S.J.

    1983-03-13

    Disclosed is an improved process for manufacturing gallium arsenide semiconductor devices having as its components a n-type gallium arsenide substrate layer and a p-type gallium arsenide diffused layer. The improved process comprises forming a pure silver ohmic contact to both the diffuse layer and the substrate layer wherein the n-type layer comprises a substantially low doping carrier concentration.

  9. Pure silver ohmic contacts to N- and P- type gallium arsenide materials

    DOEpatents

    Hogan, Stephen J.

    1986-01-01

    Disclosed is an improved process for manufacturing gallium arsenide semiconductor devices having as its components an n-type gallium arsenide substrate layer and a p-type gallium arsenide diffused layer. The improved process comprises forming a pure silver ohmic contact to both the diffused layer and the substrate layer, wherein the n-type layer comprises a substantially low doping carrier concentration.

  10. Iron-boron pairing kinetics in illuminated p-type and in boron/phosphorus co-doped n-type silicon

    NASA Astrophysics Data System (ADS)

    Möller, Christian; Bartel, Til; Gibaja, Fabien; Lauer, Kevin

    2014-07-01

    Iron-boron (FeB) pairing is observed in the n-type region of a boron and phosphorus co-doped silicon sample which is unexpected from the FeB pair model of Kimerling and Benton. To explain the experimental data, the existing FeB pair model is extended by taking into account the electronic capture and emission rates at the interstitial iron (Fei) trap level as a function of the charge carrier densities. According to this model, the charge state of the Fei may be charged in n-type making FeB association possible. Further, FeB pair formation during illumination in p-type silicon is investigated. This permits the determination of the charge carrier density dependent FeB dissociation rate and in consequence allows to determine the acceptor concentration in the co-doped n-type silicon by lifetime measurement.

  11. Iron-boron pairing kinetics in illuminated p-type and in boron/phosphorus co-doped n-type silicon

    SciTech Connect

    Möller, Christian; Bartel, Til; Gibaja, Fabien; Lauer, Kevin

    2014-07-14

    Iron-boron (FeB) pairing is observed in the n-type region of a boron and phosphorus co-doped silicon sample which is unexpected from the FeB pair model of Kimerling and Benton. To explain the experimental data, the existing FeB pair model is extended by taking into account the electronic capture and emission rates at the interstitial iron (Fe{sub i}) trap level as a function of the charge carrier densities. According to this model, the charge state of the Fe{sub i} may be charged in n-type making FeB association possible. Further, FeB pair formation during illumination in p-type silicon is investigated. This permits the determination of the charge carrier density dependent FeB dissociation rate and in consequence allows to determine the acceptor concentration in the co-doped n-type silicon by lifetime measurement.

  12. Superparamagnetic iron oxide nanoparticle attachment on array of micro test tubes and microbeakers formed on p-type silicon substrate for biosensor applications

    NASA Astrophysics Data System (ADS)

    Ghoshal, Sarmishtha; Ansar, Abul Am; Raja, Sufi O.; Jana, Arpita; Bandyopadhyay, Nil R.; Dasgupta, Anjan K.; Ray, Mallar

    2011-10-01

    A uniformly distributed array of micro test tubes and microbeakers is formed on a p-type silicon substrate with tunable cross-section and distance of separation by anodic etching of the silicon wafer in N, N-dimethylformamide and hydrofluoric acid, which essentially leads to the formation of macroporous silicon templates. A reasonable control over the dimensions of the structures could be achieved by tailoring the formation parameters, primarily the wafer resistivity. For a micro test tube, the cross-section (i.e., the pore size) as well as the distance of separation between two adjacent test tubes (i.e., inter-pore distance) is typically approximately 1 μm, whereas, for a microbeaker the pore size exceeds 1.5 μm and the inter-pore distance could be less than 100 nm. We successfully synthesized superparamagnetic iron oxide nanoparticles (SPIONs), with average particle size approximately 20 nm and attached them on the porous silicon chip surface as well as on the pore walls. Such SPION-coated arrays of micro test tubes and microbeakers are potential candidates for biosensors because of the biocompatibility of both silicon and SPIONs. As acquisition of data via microarray is an essential attribute of high throughput bio-sensing, the proposed nanostructured array may be a promising step in this direction.

  13. Inorganic Nano Light-Emitting Transistor: p-Type Porous Silicon Nanowire/n-Type ZnO Nanofilm.

    PubMed

    Lee, Sang Hoon; Kim, Jong Woo; Lee, Tae Il; Myoung, Jae Min

    2016-08-01

    An inorganic nano light-emitting transistor (INLET) consisting of p-type porous Si nanowires (PoSiNWs) and an n-type ZnO nanofilm was integrated on a heavily doped p-type Si substrate with a thermally grown SiO2 layer. To verify that modulation of the Fermi level of the PoSiNWs is key for switchable light emitting, I-V and electroluminescent characteristics of the INLET are investigated as a function of gate bias (V g ). As the V g is changed from 0 V to -20 V, the current level and light-emission intensity in the orange-red range increase by three and two times, respectively, with a forward bias of 20 V in the p-n junction, compared to those at a V g of 0 V. On the other hand, as the V g approaches 10 V, the current level decreases and the emission intensity is reduced and then finally switched off. This result arises from the modulation of the Fermi level of the PoSiNWs and the built-in potential at the p-n junction by the applied gate electric field. PMID:27378257

  14. Inorganic Nano Light-Emitting Transistor: p-Type Porous Silicon Nanowire/n-Type ZnO Nanofilm.

    PubMed

    Lee, Sang Hoon; Kim, Jong Woo; Lee, Tae Il; Myoung, Jae Min

    2016-08-01

    An inorganic nano light-emitting transistor (INLET) consisting of p-type porous Si nanowires (PoSiNWs) and an n-type ZnO nanofilm was integrated on a heavily doped p-type Si substrate with a thermally grown SiO2 layer. To verify that modulation of the Fermi level of the PoSiNWs is key for switchable light emitting, I-V and electroluminescent characteristics of the INLET are investigated as a function of gate bias (V g ). As the V g is changed from 0 V to -20 V, the current level and light-emission intensity in the orange-red range increase by three and two times, respectively, with a forward bias of 20 V in the p-n junction, compared to those at a V g of 0 V. On the other hand, as the V g approaches 10 V, the current level decreases and the emission intensity is reduced and then finally switched off. This result arises from the modulation of the Fermi level of the PoSiNWs and the built-in potential at the p-n junction by the applied gate electric field.

  15. Development of Edgeless Silicon Pixel Sensors on p-type substrate for the ATLAS High-Luminosity Upgrade

    NASA Astrophysics Data System (ADS)

    Calderini, G.; Bagolini, A.; Beccherle, R.; Bomben, M.; Boscardin, M.; Bosisio, L.; Chauveau, J.; Giacomini, G.; La Rosa, A.; Marchiori, G.; Zorzi, N.

    2016-09-01

    In view of the LHC upgrade phases towards the High Luminosity LHC (HL-LHC), the ATLAS experiment plans to upgrade the Inner Detector with an all-silicon system. The n-on-p silicon technology is a promising candidate to achieve a large area instrumented with pixel sensors, since it is radiation hard and cost effective. The presentation describes the performance of novel n-in-p edgeless planar pixel sensors produced by FBK-CMM, making use of the active trench for the reduction of the dead area at the periphery of the device. After discussing the sensor technology, some feedback from preliminary results of the first beam test will be discussed.

  16. Design and analysis of nanowire p-type MOSFET coaxially having silicon core and germanium peripheral channel

    NASA Astrophysics Data System (ADS)

    Yu, Eunseon; Cho, Seongjae

    2016-11-01

    In this work, a nanowire p-type metal–oxide–semiconductor field-effect transistor (PMOSFET) coaxially having a Si core and a Ge peripheral channel is designed and characterized by device simulations. Owing to the high hole mobility of Ge, the device can be utilized for high-speed CMOS integrated circuits, with the effective confinement of mobile holes in Ge by the large valence band offset between Si and Ge. Source/drain doping concentrations and the ratio between the Si core and Ge channel thicknesses are determined. On the basis of the design results, the channel length is aggressively scaled down by evaluating the primary DC parameters in order to confirm device scalability and low-power applicability in sub-10-nm technology nodes.

  17. Rectification properties of n-type nanocrystalline diamond heterojunctions to p-type silicon carbide at high temperatures

    SciTech Connect

    Goto, Masaki; Amano, Ryo; Shimoda, Naotaka; Kato, Yoshimine; Teii, Kungen

    2014-04-14

    Highly rectifying heterojunctions of n-type nanocrystalline diamond (NCD) films to p-type 4H-SiC substrates are fabricated to develop p-n junction diodes operable at high temperatures. In reverse bias condition, a potential barrier for holes at the interface prevents the injection of reverse leakage current from the NCD into the SiC and achieves the high rectification ratios of the order of 10{sup 7} at room temperature and 10{sup 4} even at 570 K. The mechanism of the forward current injection is described with the upward shift of the defect energy levels in the NCD to the conduction band of the SiC by forward biasing. The forward current shows different behavior from typical SiC Schottky diodes at high temperatures.

  18. Electrical properties and surface morphology of electron beam evaporated p-type silicon thin films on polyethylene terephthalate for solar cells applications

    SciTech Connect

    Ang, P. C.; Ibrahim, K.; Pakhuruddin, M. Z.

    2015-04-24

    One way to realize low-cost thin film silicon (Si) solar cells fabrication is by depositing the films with high-deposition rate and manufacturing-compatible electron beam (e-beam) evaporation onto inexpensive foreign substrates such as glass or plastic. Most of the ongoing research is reported on e-beam evaporation of Si films on glass substrates to make polycrystalline solar cells but works combining both e-beam evaporation and plastic substrates are still scarce in the literature. This paper studies electrical properties and surface morphology of 1 µm electron beam evaporated Al-doped p-type silicon thin films on textured polyethylene terephthalate (PET) substrate for application as an absorber layer in solar cells. In this work, Si thin films with different doping concentrations (including an undoped reference) are prepared by e-beam evaporation. Energy dispersion X-ray (EDX) showed that the Si films are uniformly doped by Al dopant atoms. With increased Al/Si ratio, doping concentration increased while both resistivity and carrier mobility of the films showed opposite relationships. Root mean square (RMS) surface roughness increased. Overall, the Al-doped Si film with Al/Si ratio of 2% (doping concentration = 1.57×10{sup 16} atoms/cm{sup 3}) has been found to provide the optimum properties of a p-type absorber layer for fabrication of thin film Si solar cells on PET substrate.

  19. Direct ultrasensitive electrical detection of prostate cancer biomarkers with CMOS-compatible n- and p-type silicon nanowire sensor arrays

    NASA Astrophysics Data System (ADS)

    Gao, Anran; Lu, Na; Dai, Pengfei; Fan, Chunhai; Wang, Yuelin; Li, Tie

    2014-10-01

    Sensitive and quantitative analysis of proteins is central to disease diagnosis, drug screening, and proteomic studies. Here, a label-free, real-time, simultaneous and ultrasensitive prostate-specific antigen (PSA) sensor was developed using CMOS-compatible silicon nanowire field effect transistors (SiNW FET). Highly responsive n- and p-type SiNW arrays were fabricated and integrated on a single chip with a complementary metal oxide semiconductor (CMOS) compatible anisotropic self-stop etching technique which eliminated the need for a hybrid method. The incorporated n- and p-type nanowires revealed complementary electrical response upon PSA binding, providing a unique means of internal control for sensing signal verification. The highly selective, simultaneous and multiplexed detection of PSA marker at attomolar concentrations, a level useful for clinical diagnosis of prostate cancer, was demonstrated. The detection ability was corroborated to be effective by comparing the detection results at different pH values. Furthermore, the real-time measurement was also carried out in a clinically relevant sample of blood serum, indicating the practicable development of rapid, robust, high-performance, and low-cost diagnostic systems.Sensitive and quantitative analysis of proteins is central to disease diagnosis, drug screening, and proteomic studies. Here, a label-free, real-time, simultaneous and ultrasensitive prostate-specific antigen (PSA) sensor was developed using CMOS-compatible silicon nanowire field effect transistors (SiNW FET). Highly responsive n- and p-type SiNW arrays were fabricated and integrated on a single chip with a complementary metal oxide semiconductor (CMOS) compatible anisotropic self-stop etching technique which eliminated the need for a hybrid method. The incorporated n- and p-type nanowires revealed complementary electrical response upon PSA binding, providing a unique means of internal control for sensing signal verification. The highly

  20. Sub-band transport mechanism and switching properties for resistive switching nonvolatile memories with structure of silver/aluminum oxide/p-type silicon

    SciTech Connect

    Liu, Yanhong; Li, La; Wang, Song; Gao, Ping; Pan, Lujun; Zhang, Jialiang; Zhou, Peng; Li, Jinhua; Weng, Zhankun

    2015-02-09

    In this paper, we discuss a model of sub-band in resistive switching nonvolatile memories with a structure of silver/aluminum oxide/p-type silicon (Ag/Al{sub x}O{sub y}/p-Si), in which the sub-band is formed by overlapping of wave functions of electron-occupied oxygen vacancies in Al{sub x}O{sub y} layer deposited by atomic layer deposition technology. The switching processes exhibit the characteristics of the bipolarity, discreteness, and no need of forming process, all of which are discussed deeply based on the model of sub-band. The relationships between the SET voltages and distribution of trap levels are analyzed qualitatively. The semiconductor-like behaviors of ON-state resistance affirm the sub-band transport mechanism instead of the metal filament mechanism.

  1. Direct ultrasensitive electrical detection of prostate cancer biomarkers with CMOS-compatible n- and p-type silicon nanowire sensor arrays.

    PubMed

    Gao, Anran; Lu, Na; Dai, Pengfei; Fan, Chunhai; Wang, Yuelin; Li, Tie

    2014-11-01

    Sensitive and quantitative analysis of proteins is central to disease diagnosis, drug screening, and proteomic studies. Here, a label-free, real-time, simultaneous and ultrasensitive prostate-specific antigen (PSA) sensor was developed using CMOS-compatible silicon nanowire field effect transistors (SiNW FET). Highly responsive n- and p-type SiNW arrays were fabricated and integrated on a single chip with a complementary metal oxide semiconductor (CMOS) compatible anisotropic self-stop etching technique which eliminated the need for a hybrid method. The incorporated n- and p-type nanowires revealed complementary electrical response upon PSA binding, providing a unique means of internal control for sensing signal verification. The highly selective, simultaneous and multiplexed detection of PSA marker at attomolar concentrations, a level useful for clinical diagnosis of prostate cancer, was demonstrated. The detection ability was corroborated to be effective by comparing the detection results at different pH values. Furthermore, the real-time measurement was also carried out in a clinically relevant sample of blood serum, indicating the practicable development of rapid, robust, high-performance, and low-cost diagnostic systems.

  2. Thick-film materials for silicon photovoltaic cell manufacture

    NASA Technical Reports Server (NTRS)

    Field, M. B.

    1977-01-01

    Thick film technology is applicable to three areas of silicon solar cell fabrication; metallization, junction formation, and coating for protection of screened ohmic contacts, particularly wrap around contacts, interconnection and environmental protection. Both material and process parameters were investigated. Printed ohmic contacts on n- and p-type silicon are very sensitive to the processing parameters of firing time, temperature, and atmosphere. Wrap around contacts are easily achieved by first printing and firing a dielectric over the edge and subsequently applying a low firing temperature conductor. Interconnection of cells into arrays can be achieved by printing and cofiring thick film metal pastes, soldering, or with heat curing conductive epoxies on low cost substrates. Printed (thick) film vitreous protection coatings do not yet offer sufficient optical uniformity and transparency for use on silicon. A sprayed, heat curable SiO2 based resin shows promise of providing both optical matching and environmental protection.

  3. Realizing high figure of merit in heavy-band p-type half-Heusler thermoelectric materials.

    PubMed

    Fu, Chenguang; Bai, Shengqiang; Liu, Yintu; Tang, Yunshan; Chen, Lidong; Zhao, Xinbing; Zhu, Tiejun

    2015-01-01

    Solid-state thermoelectric technology offers a promising solution for converting waste heat to useful electrical power. Both high operating temperature and high figure of merit zT are desirable for high-efficiency thermoelectric power generation. Here we report a high zT of ∼1.5 at 1,200 K for the p-type FeNbSb heavy-band half-Heusler alloys. High content of heavier Hf dopant simultaneously optimizes the electrical power factor and suppresses thermal conductivity. Both the enhanced point-defect and electron-phonon scatterings contribute to a significant reduction in the lattice thermal conductivity. An eight couple prototype thermoelectric module exhibits a high conversion efficiency of 6.2% and a high power density of 2.2 W cm(-2) at a temperature difference of 655 K. These findings highlight the optimization strategy for heavy-band thermoelectric materials and demonstrate a realistic prospect of high-temperature thermoelectric modules based on half-Heusler alloys with low cost, excellent mechanical robustness and stability.

  4. Realizing high figure of merit in heavy-band p-type half-Heusler thermoelectric materials

    PubMed Central

    Fu, Chenguang; Bai, Shengqiang; Liu, Yintu; Tang, Yunshan; Chen, Lidong; Zhao, Xinbing; Zhu, Tiejun

    2015-01-01

    Solid-state thermoelectric technology offers a promising solution for converting waste heat to useful electrical power. Both high operating temperature and high figure of merit zT are desirable for high-efficiency thermoelectric power generation. Here we report a high zT of ∼1.5 at 1,200 K for the p-type FeNbSb heavy-band half-Heusler alloys. High content of heavier Hf dopant simultaneously optimizes the electrical power factor and suppresses thermal conductivity. Both the enhanced point-defect and electron–phonon scatterings contribute to a significant reduction in the lattice thermal conductivity. An eight couple prototype thermoelectric module exhibits a high conversion efficiency of 6.2% and a high power density of 2.2 W cm−2 at a temperature difference of 655 K. These findings highlight the optimization strategy for heavy-band thermoelectric materials and demonstrate a realistic prospect of high-temperature thermoelectric modules based on half-Heusler alloys with low cost, excellent mechanical robustness and stability. PMID:26330371

  5. Realizing high figure of merit in heavy-band p-type half-Heusler thermoelectric materials

    NASA Astrophysics Data System (ADS)

    Fu, Chenguang; Bai, Shengqiang; Liu, Yintu; Tang, Yunshan; Chen, Lidong; Zhao, Xinbing; Zhu, Tiejun

    2015-09-01

    Solid-state thermoelectric technology offers a promising solution for converting waste heat to useful electrical power. Both high operating temperature and high figure of merit zT are desirable for high-efficiency thermoelectric power generation. Here we report a high zT of ~1.5 at 1,200 K for the p-type FeNbSb heavy-band half-Heusler alloys. High content of heavier Hf dopant simultaneously optimizes the electrical power factor and suppresses thermal conductivity. Both the enhanced point-defect and electron-phonon scatterings contribute to a significant reduction in the lattice thermal conductivity. An eight couple prototype thermoelectric module exhibits a high conversion efficiency of 6.2% and a high power density of 2.2 W cm-2 at a temperature difference of 655 K. These findings highlight the optimization strategy for heavy-band thermoelectric materials and demonstrate a realistic prospect of high-temperature thermoelectric modules based on half-Heusler alloys with low cost, excellent mechanical robustness and stability.

  6. Effect of Rapid Thermal Processing on Light-Induced Degradation of Carrier Lifetime in Czochralski p-Type Silicon Bare Wafers

    NASA Astrophysics Data System (ADS)

    Kouhlane, Y.; Bouhafs, D.; Khelifati, N.; Belhousse, S.; Menari, H.; Guenda, A.; Khelfane, A.

    2016-11-01

    The electrical properties of Czochralski silicon (Cz-Si) p-type boron-doped bare wafers have been investigated after rapid thermal processing (RTP) with different peak temperatures. Treated wafers were exposed to light for various illumination times, and the effective carrier lifetime ( τ eff) measured using the quasi-steady-state photoconductance (QSSPC) technique. τ eff values dropped after prolonged illumination exposure due to light-induced degradation (LID) related to electrical activation of boron-oxygen (BO) complexes, except in the sample treated with peak temperature of 785°C, for which the τ eff degradation was less pronounced. Also, a reduction was observed when using the 830°C peak temperature, an effect that was enhanced by alteration of the wafer morphology (roughness). Furthermore, the electrical resistivity presented good stability under light exposure as a function of temperature compared with reference wafers. Additionally, the optical absorption edge shifted to higher wavelength, leading to increased free-carrier absorption by treated wafers. Moreover, a theoretical model is used to understand the lifetime degradation and regeneration behavior as a function of illumination time. We conclude that RTP plays an important role in carrier lifetime regeneration for Cz-Si wafers via modification of optoelectronic and structural properties. The balance between an optimized RTP cycle and the rest of the solar cell elaboration process can overcome the negative effect of LID and contribute to achievement of higher solar cell efficiency and module performance.

  7. Fabrication and characterization of silicon nanowire p-i-n MOS gated diode for use as p-type tunnel FET

    NASA Astrophysics Data System (ADS)

    Brouzet, V.; Salem, B.; Periwal, P.; Rosaz, G.; Baron, T.; Bassani, F.; Gentile, P.; Ghibaudo, G.

    2015-11-01

    In this paper, we present the fabrication and electrical characterization of a MOS gated diode based on axially doped silicon nanowire (NW) p-i-n junctions. These nanowires are grown by chemical vapour deposition (CVD) using the vapour-liquid-solid (VLS) mechanism. NWs have a length of about 7 \\upmu {m} with 3 \\upmu {m} of doped regions (p-type and n-type) and 1 \\upmu {m} of intrinsic region. The gate stack is composed of 15 nm of hafnium dioxide ({HfO}2), 80 nm of nickel and 120 nm of aluminium. At room temperature, I_{{on}} =-52 {nA}/\\upmu {m} (V_{{DS}}=-0.5 {V}, V_{{GS}}=-4 {V}), and an I_{{on}}/I_{{off}} ratio of about 104 with a very low I_{{off}} current has been obtained. Electrical measurements are carried out between 90 and 390 K, and we show that the I on current is less temperature dependent below 250 K. We also observe that the ON current is increasing between 250 and 390 K. These transfer characteristics at low and high temperature confirm the tunnelling transport mechanisms in our devices.

  8. Effect of Rapid Thermal Processing on Light-Induced Degradation of Carrier Lifetime in Czochralski p-Type Silicon Bare Wafers

    NASA Astrophysics Data System (ADS)

    Kouhlane, Y.; Bouhafs, D.; Khelifati, N.; Belhousse, S.; Menari, H.; Guenda, A.; Khelfane, A.

    2016-07-01

    The electrical properties of Czochralski silicon (Cz-Si) p-type boron-doped bare wafers have been investigated after rapid thermal processing (RTP) with different peak temperatures. Treated wafers were exposed to light for various illumination times, and the effective carrier lifetime (τ eff) measured using the quasi-steady-state photoconductance (QSSPC) technique. τ eff values dropped after prolonged illumination exposure due to light-induced degradation (LID) related to electrical activation of boron-oxygen (BO) complexes, except in the sample treated with peak temperature of 785°C, for which the τ eff degradation was less pronounced. Also, a reduction was observed when using the 830°C peak temperature, an effect that was enhanced by alteration of the wafer morphology (roughness). Furthermore, the electrical resistivity presented good stability under light exposure as a function of temperature compared with reference wafers. Additionally, the optical absorption edge shifted to higher wavelength, leading to increased free-carrier absorption by treated wafers. Moreover, a theoretical model is used to understand the lifetime degradation and regeneration behavior as a function of illumination time. We conclude that RTP plays an important role in carrier lifetime regeneration for Cz-Si wafers via modification of optoelectronic and structural properties. The balance between an optimized RTP cycle and the rest of the solar cell elaboration process can overcome the negative effect of LID and contribute to achievement of higher solar cell efficiency and module performance.

  9. Novel silicone materials for LED packaging

    NASA Astrophysics Data System (ADS)

    Norris, Ann W.; Bahadur, Maneesh; Yoshitake, Makoto

    2005-09-01

    Silicone based materials have attracted considerable attention from Light Emitting Diode (LED) manufacturers for use as encapsulants and lenses for many next generation LED device designs. Silicones can function in several roles that include protective lenses, stress relieving encapsulants, mechanical protection and light path materials. The key attributes of silicones that make them attractive materials for high brightness (HB) LEDs include their high transparency in the UV-visible region, controlled refractive index (RI), stable thermo-mechanical properties, and tuneable hardness from soft gels to hard resins. The high current and high operating temperatures of HB-LEDs present a significant materials challenge for traditional organic materials such as epoxies, acrylics and cyclo olefin copolymers (COC) that lack the thermal and molecular stability needed to provide optical clarity and mechanical performance required for next generation devices. In addition, the retention of optical clarity over the lifetime of the device, which involves long term exposure to high flux in the UV-visible wavelength region, is a critical requirement. Silicones have been demonstrated to provide the required stability. This paper will describe recent silicone materials development efforts directed towards providing LED manufacturers with silicone materials solutions for LED device fabrication. Injection molding of novel silicone resin based materials will be discussed as a surmountable challenge for high throughput LED device manufacturing.

  10. Silicon mitigates heavy metal stress by regulating P-type heavy metal ATPases, Oryza sativa low silicon genes, and endogenous phytohormones

    PubMed Central

    2014-01-01

    Background Silicon (Si) application has been known to enhance the tolerance of plants against abiotic stresses. However, the protective mechanism of Si under heavy metals contamination is poorly understood. The aim of this study was to assess the role of Si in counteracting toxicity due to cadmium (Cd) and copper (Cu) in rice plants (Oryza sativa). Results Si significantly improved the growth and biomass of rice plants and reduced the toxic effects of Cd/Cu after different stress periods. Si treatment ameliorated root function and structure compared with non-treated rice plants, which suffered severe root damage. In the presence of Si, the Cd/Cu concentration was significantly lower in rice plants, and there was also a reduction in lipid peroxidation and fatty acid desaturation in plant tissues. The reduced uptake of metals in the roots modulated the signaling of phytohormones involved in responses to stress and host defense, such as abscisic acid, jasmonic acid, and salicylic acid. Furthermore, the low concentration of metals significantly down regulated the mRNA expression of enzymes encoding heavy metal transporters (OsHMA2 and OsHMA3) in Si-metal-treated rice plants. Genes responsible for Si transport (OsLSi1 and OsLSi2), showed a significant up-regulation of mRNA expression with Si treatment in rice plants. Conclusion The present study supports the active role of Si in the regulation of stresses from heavy metal exposure through changes in root morphology. PMID:24405887

  11. Infrared Reflectance and Ultrahigh Vacuum Cathodoluminescence of Aluminum Nitride-Gallium Nitride Short Period Superlattice Films and P-Type Porous 6h Silicon Carbide Layers

    NASA Astrophysics Data System (ADS)

    MacMillan, Michael F.

    The room temperature infrared reflectance of AlN -GaN short period superlattice films was measured. These superlattice films were deposited by switched atomic layer metal organic chemical vapor deposition onto GaN or AlN buffer layers deposited on basal plane sapphire substrates. The measured reflectance spectra are compared to calculated spectra generated using an effective medium theory to model the dielectric function of the superlattice. Optical properties of the individual materials comprising the samples are modeled with Lorentz oscillators using bulk input parameters. The effects of film and substrate anisotropy and off normal incidence are included in the calculation. Using this modeling technique, thickness estimates for the total superlattice film and the buffer layer are obtained. Cathodoluminescence of AlN-GaN short period superlattice films was measured at 6K, 77K and room temperature, and at several electron acceleration voltages to allow depth profiling of the samples. An ultraviolet peak located above the band gap energy of GaN is present in all samples and persists from 6K to room temperature. Using the film and buffer thicknesses determined by the reflectance measurement this ultraviolet peak is identified as originating from the superlattice layer. Preliminary results indicate that this peak is due to quantum confinement in the GaN layers. The room temperature infrared reflectance of thick p-type porous 6H SiC layers was measured. Samples were fabricated by anodization of p-type 6H SiC bulk crystals in dilute HF. Striking differences are seen between the reststrahl region reflectance of these porous layers and that of bulk 6H SiC crystals. Several effective medium models, which assume different morphologies of the component materials, 6H SiC and air, were used to model the dielectric function of porous SiC. Calculated reflectance spectra, generated using these dielectric functions, are compared to experimental porous SiC spectra, allowing us to

  12. Ternary chalcogenides Cs2Zn3Se4 and Cs2Zn3Te4 : Potential p -type transparent conducting materials

    DOE PAGESBeta

    Shi, Hongliang; Saparov, Bayrammurad; Singh, David J.; Sefat, Athena S.; Du, Mao-Hua

    2014-11-11

    Here we report prediction of two new ternary chalcogenides that can potentially be used as p-type transparent conductors along with experimental synthesis and initial characterization of these previously unknown compounds, Cs2Zn3Ch4 (Ch = Se, Te). In particular, the structures are predicted based on density functional calculations and confirmed by experiments. Phase diagrams, electronic structure, optical properties, and defect properties of Cs2Zn3Se4 and Cs2Zn3Te4 are calculated to assess the viability of these materials as p-type TCMs. Cs2Zn3Se4 and Cs2Zn3Te4, which are stable under ambient air, display large optical band gaps (calculated to be 3.61 and 2.83 eV, respectively) and have smallmore » hole effective masses (0.5-0.77 me) that compare favorably with other proposed p-type TCMs. Defect calculations show that undoped Cs2Zn3Se4 and Cs2Zn3Te4 are p-type materials. However, the free hole concentration may be limited by low-energy native donor defects, e.g., Zn interstitials. Lastly, non-equilibrium growth techniques should be useful for suppressing the formation of native donor defects, thereby increasing the hole concentration.« less

  13. Thick film silicon growth techniques. [die materials

    NASA Technical Reports Server (NTRS)

    Bates, H. E.; Mlavsky, A. I.; Jewett, D. N.; White, V. E.

    1973-01-01

    The research which was directed toward finding an improved die material is reported. Wetting experiments were conducted with various materials to determine their compatibility with silicon. Work has also continued toward the development of quartz as a die material as new techniques have provided more optimistic results than observed in the past. As a result of the thermal modification previously described, improvements in growth stability have contributed to an increase in ribbon quality.

  14. Method of fabricating n-type and p-type microcrystalline semiconductor alloy material including band gap widening elements

    DOEpatents

    Guha, Subhendu; Ovshinsky, Stanford R.

    1990-02-02

    A method of fabricating doped microcrystalline semiconductor alloy material which includes a band gap widening element through a glow discharge deposition process by subjecting a precursor mixture which includes a diluent gas to an a.c. glow discharge in the absence of a magnetic field of sufficient strength to induce electron cyclotron resonance.

  15. Process Research of Polycrystalline Silicon Material (PROPSM)

    NASA Technical Reports Server (NTRS)

    Culik, J. S.

    1984-01-01

    A passivation process (hydrogenation) that will improve the power generation of solar cells fabricated from presently produced, large grain, cast polycrystalline silicon (Semix), a potentially low cost material are developed. The first objective is to verify the operation of a DC plasma hydrogenation system and to investigate the effect of hydrogen on the electrical performance of a variety of polycrystalline silicon solar cells. The second objective is to parameterize and optimize a hydrogenation process for cast polycrystalline silicon, and will include a process sensitivity analysis. The sample preparation for the first phase is outlined. The hydrogenation system is described, and some early results that were obtained using the hydrogenation system without a plasma are summarized. Light beam induced current (LBIC) measurements of minicell samples, and their correlation to dark current voltage characteristics, are discussed.

  16. Semiconductor systems utilizing materials that form rectifying junctions in both N and P-type doping regions, whether metallurgically or field induced, and methods of use

    DOEpatents

    Welch, James D.

    2000-01-01

    Disclosed are semiconductor systems, such as integrated circuits utilizing Schotky barrier and/or diffused junction technology, which semiconductor systems incorporate material(s) that form rectifying junctions in both metallurgically and/or field induced N and P-type doping regions, and methods of their use. Disclosed are Schottky barrier based inverting and non-inverting gate voltage channel induced semiconductor single devices with operating characteristics similar to multiple device CMOS systems and which can be operated as modulators, N and P-channel MOSFETS and CMOS formed therefrom, and (MOS) gate voltage controlled rectification direction and gate voltage controlled switching devices, and use of such material(s) to block parasitic current flow pathways. Simple demonstrative five mask fabrication procedures for inverting and non-inverting gate voltage channel induced semiconductor single devices with operating characteristics similar to multiple device CMOS systems are also presented.

  17. Mirowave annealing of silicon nitride materials

    SciTech Connect

    Kiggans, J.O. Jr.; Montgomery, F.C.; Tiegs, T.N.

    1997-08-01

    Dense silicon nitride-based ceramics were microwave annealed to determine if microwave heating offers advantages over conventional heating for the enhancement of the high temperature creep resistance. Gas pressure sintered silicon nitride (GPS-SN) and sintered reaction-bonded silicon nitride (SRBSN) were heated in microwave or graphite element furnaces at 1150{degrees}C and 1600{degrees}C. Annealed materials were characterized for the room and high temperature flexural strengths, room temperature fracture toughness values, and high temperature creep properties. In addition, SEM analyses were performed to study grain growth and other microstructural changes. The results of this study showed that both types of furnace anneals at 1150{degrees}C lowered the room temperature strength and toughness values of both SRBSN and GPS-SN materials; however, the anneal treatments at 1600{degrees}C had little effect on the room temperature properties. Both the SRBSN and GPS-SN control and annealed samples had reduced high temperature fast fracture strengths, when compared to the room temperature strengths. Creep tests at 1200{degrees}C indicated that both the SRBSN and the GPS-SN materials that were annealed by microwave heating at I 150{degrees}C for 20 h showed enhanced creep resistance, when compared to unheated controls and conventionally heated materials. No qualitative differences were seen in the microstructures of the SRBSN and the GPS-SN materials which could account for the differences in the creep properties of the annealed materials. Additional experimental work is in progress to further understand the mechanisms for the enhanced creep properties of silicon nitride materials annealed by microwave heating.

  18. Replacement of silicone polymer A with silicone polymer B and the subsequent characterization of the new cellular silicone materials

    SciTech Connect

    Schneider, J.W.

    1994-04-01

    The purpose of this project is to replace silicone polymer A with silicone polymer B produced by Vendor B. Silicone polymer B and the resulting B-50 cellular silicone have been used to produce cushions for the W87 program. Approximately 5.5 years of stress relaxation aging study data as well as actual part surveillance data have been collected, characterizing the stockpile life performance of the B-50 cellular silicone cushion material. Process characterization of new cellular silicone materials as a result of replacing silicone polymer A with silicone polymer B has been completed. Load deflection requirements for the new cellular silicone materials based on silicone polymer B have been met. The silicone polymer B based cellular silicone materials must be compounded at densities of approximately 0.03 g/cm{sup 3} less than the silicone polymer A based cellular silicone materials in order to achieve the same load deflection requirements has also been demonstrated. The change in silicone polymers from A to B involved a decrease in volatile content as well as a decrease in part shrinkage.

  19. Preparation and LPG-gas sensing characteristics of p-type semiconducting LaNbO4 ceramic material

    NASA Astrophysics Data System (ADS)

    Balamurugan, C.; Lee, D.-W.; Subramania, A.

    2013-10-01

    Lanthanam niobate (LaNbO4) nanopowder was synthesized by a low temperature solution-based process. Thermal analysis TG/DTA, XRD, SEM, TEM, EDX, impedance analysis and Brunauer-Emmett-Teller (BET) were used to characterize the precursor and the calcined LaNbO4 powders. The gas sensing behavior of LaNbO4 nanopowder was studied with gases like liquid petroleum gas (LPG), ammonia (NH3), and ethanol (C2H5OH), as a function of various controlling factors like operating temperature, concentration of the gas and response time. It revealed that LaNbO4 is a very promising material for the detection of LPG (80%) and NH3 (59%) at relatively lower operating temperatures.

  20. Eco-friendly p-type Cu2SnS3 thermoelectric material: crystal structure and transport properties

    PubMed Central

    Shen, Yawei; Li, Chao; Huang, Rong; Tian, Ruoming; Ye, Yang; Pan, Lin; Koumoto, Kunihito; Zhang, Ruizhi; Wan, Chunlei; Wang, Yifeng

    2016-01-01

    As a new eco-friendly thermoelectric material, copper tin sulfide (Cu2SnS3) ceramics were experimentally studied by Zn-doping. Excellent electrical transport properties were obtained by virtue of 3-dimensionally conductive network for holes, which are less affected by the coexistence of cubic and tetragonal phases that formed upon Zn subsitition for Sn; a highest power factors ~0.84 mW m−1 K−2 at 723 K was achieved in the 20% doped sample. Moreover, an ultralow lattice thermal conductivity close to theoretical minimum was observed in these samples, which could be related to the disordering of atoms in the coexisting cubic and tetragonal phases and the interfaces. Thanks to the phonon-glass-electron-crystal features, a maximum ZT ~ 0.58 was obtained at 723 K, which stands among the tops for sulfide thermoelectrics at the same temperature. PMID:27666524

  1. P-type gallium nitride

    DOEpatents

    Rubin, M.; Newman, N.; Fu, T.; Ross, J.; Chan, J.

    1997-08-12

    Several methods have been found to make p-type gallium nitride. P-type gallium nitride has long been sought for electronic devices. N-type gallium nitride is readily available. Discovery of p-type gallium nitride and the methods for making it will enable its use in ultraviolet and blue light-emitting diodes and lasers. pGaN will further enable blue photocathode elements to be made. Molecular beam epitaxy on substrates held at the proper temperatures, assisted by a nitrogen beam of the proper energy produced several types of p-type GaN with hole concentrations of about 5{times}10{sup 11} /cm{sup 3} and hole mobilities of about 500 cm{sup 2} /V-sec, measured at 250 K. P-type GaN can be formed of unintentionally-doped material or can be doped with magnesium by diffusion, ion implantation, or co-evaporation. When applicable, the nitrogen can be substituted with other group III elements such as Al. 9 figs.

  2. P-type gallium nitride

    DOEpatents

    Rubin, Michael; Newman, Nathan; Fu, Tracy; Ross, Jennifer; Chan, James

    1997-01-01

    Several methods have been found to make p-type gallium nitride. P-type gallium nitride has long been sought for electronic devices. N-type gallium nitride is readily available. Discovery of p-type gallium nitride and the methods for making it will enable its use in ultraviolet and blue light-emitting diodes and lasers. pGaN will further enable blue photocathode elements to be made. Molecular beam epitaxy on substrates held at the proper temperatures, assisted by a nitrogen beam of the proper energy produced several types of p-type GaN with hole concentrations of about 5.times.10.sup.11 /cm.sup.3 and hole mobilities of about 500 cm.sup.2 /V-sec, measured at 250.degree. K. P-type GaN can be formed of unintentionally-doped material or can be doped with magnesium by diffusion, ion implantation, or co-evaporation. When applicable, the nitrogen can be substituted with other group III elements such as Al.

  3. Nanostructured p-type semiconducting transparent oxides: promising materials for nano-active devices and the emerging field of "transparent nanoelectronics".

    PubMed

    Banerjee, Arghya; Chattopadhyay, Kalyan K

    2008-01-01

    Transparent conducting oxides (TCO) with p-type semiconductivity have recently gained renewed interest for the fabrication of all-oxide transparent junctions, having potential applications in the emerging field of 'Transparent' or 'Invisible Electronics'. This kind of transparent junctions can be used as a "functional" window, which will transmit visible portion of solar radiation, but generates electricity by the absorption of the UV part. Therefore, these devices can be used as UV shield as well as UV cells. In this report, a brief review on the research activities on various p-TCO materials is furnished along-with the fabrication of different transparent p-n homojunction, heterojunction and field-effect transistors. Also the reason behind the difficulties in obtaining p-TCO materials and possible solutions are discussed in details. Considerable attention is given in describing the various patent generations on the field of p-TCO materials as well as transparent p-n junction diodes and light emitting devices. Also, most importantly, a detailed review and patenting activities on the nanocrystalline p-TCO materials and transparent nano-active device fabrication are furnished with considerable attention. And finally, a systematic description on the fabrication and characterization of nanocrystalline, p-type transparent conducting CuAlO(2) thin film, deposited by cost-effective low-temperature DC sputtering technique, by our group, is furnished in details. These p-TCO micro/nano-materials have wide range of applications in the field of optoelectronics, nanoelectronics, space sciences, field-emission displays, thermoelectric converters and sensing devices. PMID:19076042

  4. Maxillofacial Prosthetic Materials- An Inclination Towards Silicones

    PubMed Central

    Choudhary, Sunita; Garg, Hemlata; H.G., Jagadeesh

    2014-01-01

    There have been constant searches and researches which are taking place in the field of dental materials to best suit the ideal selection criteria to satisfy the functionality, biocompatibility, aesthetics as well as the durability as a maxillofacial material. Among all the different materials, Silicone is the most popularly used, but still studies are carried out to overcome their weaknesses and to come out with a material which can be labeled as the “ideal maxillofacial prosthetic material”. This article comprises the materials which were and are in use and the reason for their unpopularity. It also gives us a scope to understand the major fields where the materials lack and thus needs improvement to render an individual with the best maxillo-facial prosthesis. PMID:25654054

  5. Reliability of two sintered silicon nitride materials

    NASA Technical Reports Server (NTRS)

    Mieskowski, D. M.; Sanders, W. A.; Pierce, L. A.

    1985-01-01

    Two types of sintered silicon nitride were evaluated in terms of reliability: an experimental high pressure nitrogen sintered material and a commercial material. The results show wide variations in strength for both materials. The Weibull moduli were 5.5, 8.9, and 11 for the experimental material at room temperature, 1200, and 1370 C, respectively. The commercial material showed Weibull moduli of 9.0, 8.6, and 8.9 at these respective temperatures. No correlation between strength and flaw size was noted for the experimental material. The applicability of the Weibull and Griffith theories to processing defects on the order of 100 microns or less in size are discussed.

  6. Carbon Cryogel Silicon Composite Anode Materials for Lithium Ion Batteries

    NASA Technical Reports Server (NTRS)

    Woodworth James; Baldwin, Richard; Bennett, William

    2010-01-01

    A variety of materials are under investigation for use as anode materials in lithium-ion batteries, of which, the most promising are those containing silicon. 10 One such material is a composite formed via the dispersion of silicon in a resorcinol-formaldehyde (RF) gel followed by pyrolysis. Two silicon-carbon composite materials, carbon microspheres and nanofoams produced from nano-phase silicon impregnated RF gel precursors have been synthesized and investigated. Carbon microspheres are produced by forming the silicon-containing RF gel into microspheres whereas carbon nano-foams are produced by impregnating carbon fiber paper with the silicon containing RF gel to create a free standing electrode. 1-4,9 Both materials have demonstrated their ability to function as anodes and utilize the silicon present in the material. Stable reversible capacities above 400 mAh/g for the bulk material and above 1000 mAh/g of Si have been observed.

  7. Cz-Silicon Produced from Solar-Grade and Recycled Materials. Part II: Investigating Performances of Solar Cell Produced from Solar-Grade Cz-Silicon

    NASA Astrophysics Data System (ADS)

    Zhang, Song; Øvrelid, Eivind Johannes; Di Sabtino, Marisa; Juel, Mari; Tranell, Gabriella

    2015-03-01

    This paper is the second of two, investigating the properties of P-type Cz-silicon materials and solar cells produced with recycled silicon and Elkem Solar Silicon (ESS) materials. While the focus on the first work was on the bulk properties and grown defects of the material, the current study focuses on the solar cell performances. In the processing of the solar cells, the phosphorous diffusion process was optimized to improve the bulk properties and thus to maximize the final solar cell characteristics. Results from the characterization of material defects suggest that the performances of the experimental ingots are limited by the activated grown-in defects, which should be strictly controlled during crystal growth and solar cell processing. The solar cells produced from the investigated ingots showed efficiency values up to 18.5 pct and fill factor values up to 79 pct, comparable to conventional silicon produced from poly silicon. Solar cells produced from mixed recycled and ESS material exhibit a better performance than 100 pct recycled material. Boron and oxygen concentration levels and net doping level showed a concurrent effect on light-induced degradation (LID). Appropriate compensation was finally demonstrated to be an efficient way to improve solar cells efficiency of Cz-silicon produced from recycled silicon, even though higher dopant concentration incurred relatively faster LID.

  8. Role of the buffer at the interface of intrinsic a-Si:H and p-type a-Si:H on amorphous/crystalline silicon heterojunction solar cells

    NASA Astrophysics Data System (ADS)

    Meng, Fanying; Shen, Leilei; Shi, Jianhua; Zhang, Liping; Liu, Jinning; Liu, Yucheng; Liu, Zhengxin

    2015-11-01

    We investigate the influence of the different buffer at the interface between the intrinsic a-Si:H and p-type a-Si:H layers on amorphous/crystalline silicon heterojunction (SHJ) solar cells performance. It is demonstrated that the ultrathin buffer at interface of intrinsic a-Si:H and p-type a-Si:H, obtained by H-rich plasma treatment on the initial intrinsic a-Si:H passivation layer, can significantly enhance the minority carrier lifetime and decrease the emitter saturation current density. Spectroscopic ellipsometry and Fourier transform infrared spectroscopy analyses indicate that the initial intrinsic a-Si:H films become dense and less defected as a result of the relaxation and reconstruction when they are treated during the H-rich plasma environment. Based on this finding combined with the optimization of surface texturization of the silicon wafer, this work allows us to reach very high Voc values over 730 mV without losses on fill factor, the 100 μm, 125 × 125 mm2 SHJ solar cells were fabricated with industry-compatible process, yielding the efficiency up to 22.5%.

  9. Tuning the interfacial hole injection barrier between p-type organic materials and Co using a MoO{sub 3} buffer layer

    SciTech Connect

    Wang Yuzhan; Wee, Andrew T. S.; Cao Liang; Qi Dongchen; Chen Wei; Gao Xingyu

    2012-08-01

    We demonstrate that the interfacial hole injection barrier {Delta}{sub h} between p-type organic materials (i.e., CuPc and pentacene) and Co substrate can be tuned by the insertion of a MoO{sub 3} buffer layer. Using ultraviolet photoemission spectroscopy, it was found that the introduction of MoO{sub 3} buffer layer effectively reduces the hole injection barrier from 0.8 eV to 0.4 eV for the CuPc/Co interface, and from 1.0 eV to 0.4 eV for the pentacene/Co interface, respectively. In addition, by varying the thickness of the buffer, the tuning effect of {Delta}{sub h} is shown to be independent of the thickness of MoO{sub 3} interlayer at both CuPc/Co and pentacene/Co interfaces. This Fermi level pinning effect can be explained by the integer charge-transfer model. Therefore, the MoO{sub 3} buffer layer has the potential to be applied in p-type organic spin valve devices to improve the device performance via reducing the interfacial hole injection barrier.

  10. Polycrystalline silicon semiconducting material by nuclear transmutation doping

    DOEpatents

    Cleland, John W.; Westbrook, Russell D.; Wood, Richard F.; Young, Rosa T.

    1978-01-01

    A NTD semiconductor material comprising polycrystalline silicon having a mean grain size less than 1000 microns and containing phosphorus dispersed uniformly throughout the silicon rather than at the grain boundaries.

  11. Recombination activity of light-activated copper defects in p-type silicon studied by injection- and temperature-dependent lifetime spectroscopy

    NASA Astrophysics Data System (ADS)

    Inglese, Alessandro; Lindroos, Jeanette; Vahlman, Henri; Savin, Hele

    2016-09-01

    The presence of copper contamination is known to cause strong light-induced degradation (Cu-LID) in silicon. In this paper, we parametrize the recombination activity of light-activated copper defects in terms of Shockley—Read—Hall recombination statistics through injection- and temperature dependent lifetime spectroscopy (TDLS) performed on deliberately contaminated float zone silicon wafers. We obtain an accurate fit of the experimental data via two non-interacting energy levels, i.e., a deep recombination center featuring an energy level at Ec-Et=0.48 -0.62 eV with a moderate donor-like capture asymmetry ( k =1.7 -2.6 ) and an additional shallow energy state located at Ec-Et=0.1 -0.2 eV , which mostly affects the carrier lifetime only at high-injection conditions. Besides confirming these defect parameters, TDLS measurements also indicate a power-law temperature dependence of the capture cross sections associated with the deep energy state. Eventually, we compare these results with the available literature data, and we find that the formation of copper precipitates is the probable root cause behind Cu-LID.

  12. Charge carrier transport and lifetimes in n-type and p-type phosphorene as 2D device active materials: an ab initio study

    NASA Astrophysics Data System (ADS)

    Tea, E.; Hin, C.

    In this work, we provide a detailed analysis of phosphorene performance as n-type and p-type active materials. The study is based on first principles calculation of phosphorene electronic structure, and resulting electron and hole scattering rates and lifetimes. Emphasis is put on extreme regimes commonly found in semiconductor devices, i.e. high electric fields and heavy doping, where impact ionization and Auger recombination can occur. We found that electron-initiated impact ionization is weaker than the hole-initiated process, when compared to carrier-phonon interaction rates, suggesting resilience to impact ionization initiated breakdown. Moreover, calculated minority electron lifetimes are limited by radiative recombination only, not by Auger processes, suggesting that phosphorene could achieve good quantum efficiencies in optoelectronic devices. The provided scattering rates and lifetimes are critical input data for the modeling and understanding of phosphorene-based device physics.

  13. Charge carrier transport and lifetimes in n-type and p-type phosphorene as 2D device active materials: an ab initio study.

    PubMed

    Tea, E; Hin, C

    2016-08-10

    In this work, we provide a detailed analysis of phosphorene's performance as an n-type and p-type active material. This study is based on first principles calculations of the phosphorene electronic structure, and the resulting electron and hole scattering rates and lifetimes. Emphasis is put on extreme regimes commonly found in semiconductor devices, i.e. high electric fields and heavy doping, where impact ionization and Auger recombination can occur. We found that electron-initiated impact ionization is weaker than the hole-initiated process, when compared to carrier-phonon interaction rates, suggesting resilience to impact ionization initiated breakdown. Moreover, calculated minority electron lifetimes are limited by radiative recombination only, not by Auger processes, suggesting that phosphorene could achieve good quantum efficiencies in optoelectronic devices. The provided scattering rates and lifetimes are critical input data for the modeling and understanding of phosphorene-based device physics.

  14. An all-solid-state perovskite-sensitized solar cell based on the dual function polyaniline as the sensitizer and p-type hole-transporting material

    NASA Astrophysics Data System (ADS)

    Xiao, Yaoming; Han, Gaoyi; Chang, Yunzhen; Zhou, Haihan; Li, Miaoyu; Li, Yanping

    2014-12-01

    High performance dual function of polyaniline (PANI) with brachyplast structure is synthesized by using a two-step cyclic voltammetry (CV) approach onto the fluorinated tin oxide (FTO) glass substrate, which acts as the sensitizer and p-type hole-transporting material (p-HTM) for the all-solid-state perovskite-sensitized solar cell (ass-PSSC) due to its π-π* transition and the localized polaron. The ass-PSSC based on the PANI delivers a photovoltaic conversion efficiency of 7.34%, and reduces from 7.34% to 6.71% after 1000 h, thereby 91.42% of the energy conversion efficiency is kept, indicating the device has a good long-term stability.

  15. Charge carrier transport and lifetimes in n-type and p-type phosphorene as 2D device active materials: an ab initio study.

    PubMed

    Tea, E; Hin, C

    2016-08-10

    In this work, we provide a detailed analysis of phosphorene's performance as an n-type and p-type active material. This study is based on first principles calculations of the phosphorene electronic structure, and the resulting electron and hole scattering rates and lifetimes. Emphasis is put on extreme regimes commonly found in semiconductor devices, i.e. high electric fields and heavy doping, where impact ionization and Auger recombination can occur. We found that electron-initiated impact ionization is weaker than the hole-initiated process, when compared to carrier-phonon interaction rates, suggesting resilience to impact ionization initiated breakdown. Moreover, calculated minority electron lifetimes are limited by radiative recombination only, not by Auger processes, suggesting that phosphorene could achieve good quantum efficiencies in optoelectronic devices. The provided scattering rates and lifetimes are critical input data for the modeling and understanding of phosphorene-based device physics. PMID:27479904

  16. Area Reports. Advanced materials and devices research area. Silicon materials research task, and advanced silicon sheet task

    NASA Technical Reports Server (NTRS)

    1986-01-01

    The objectives of the Silicon Materials Task and the Advanced Silicon Sheet Task are to identify the critical technical barriers to low-cost silicon purification and sheet growth that must be overcome to produce a PV cell substrate material at a price consistent with Flat-plate Solar Array (FSA) Project objectives and to overcome these barriers by performing and supporting appropriate R&D. Progress reports are given on silicon refinement using silane, a chemical vapor transport process for purifying metallurgical grade silicon, silicon particle growth research, and modeling of silane pyrolysis in fluidized-bed reactors.

  17. In situ study of p-type amorphous silicon growth from B2H6:SiH4 mixtures: Surface reactivity and interface effects

    NASA Astrophysics Data System (ADS)

    Collins, R. W.

    1988-09-01

    In situ ellipsometry provides monolayer sensitivity to the reaction of B2H6:SiH4 doping gas mixtures with p- and i-type plasma-enhanced chemical vapor deposited (PECVD) amorphous silicon (a-Si:H) surfaces at 180 and 250 °C. This low-temperature reaction, leading to the slow growth (1-3 Å/min) of a-Si:H:B by CVD (without plasma excitation), requires a clean a-Si:H surface and both B2H6 and SiH4 in the doping gas. We suggest that the high B content of CVD a-Si:H:B at p-i and i-p interfaces and on the film-coated regions of single-chamber reactors, may contribute to poor interface characteristics and residual contamination in devices.

  18. Temperature Dependent Capacitance-Voltage And Deep Level Transient Spectroscopy Study Of Self-Assembled Ge Quantum Dots Embedded In P-type Silicon

    SciTech Connect

    Rangel-Kuoppa, Victor-Tapio; Chen Gang; Jantsch, Wolfgang

    2011-12-23

    Temperature dependent Capacitance-Voltage (TCV) and Deep Level Transient Spectroscopy (DLTS) techniques were used to study how Ge Quantum Dots (QDs) embedded in Silicon trap charge. Atomic Force Microscopy (AFM) is used to obtain the density of QDs, which is in the order of 3x10{sup 11} cm{sup -2}. Three shallow levels, with activation energies of 40, 65 and 90 meV, and densities around 10{sup 16} cm{sup -3}, are found and are related to Boron. Four deep levels, with activation energies of 110, 150, 330 and 380 meV, and densities between 2x10{sup 15} cm{sup -3} and 5x10{sup 15} cm{sup -3}, are also found. TCV results suggest they are related to the Ge QDs.

  19. Space Environment Effects on Silicone Seal Materials

    NASA Technical Reports Server (NTRS)

    deGroh, Henry C., III; Daniels, Christopher C.; Dever, Joyce A.; Miller, Sharon K.; Waters, Deborah L.; Finkbeiner, Joshua R.; Dunlap, Patrick H.; Steinetz, Bruce M.

    2010-01-01

    A docking system is being developed by the NASA to support future space missions. It is expected to use redundant elastomer seals to help contain cabin air during dockings between two spacecraft. The sealing surfaces are exposed to the space environment when vehicles are not docked. In space, the seals will be exposed to temperatures between 125 to -75 C, vacuum, atomic oxygen, particle and ultraviolet radiation, and micrometeoroid and orbital debris (MMOD). Silicone rubber is the only class of space flight-qualified elastomeric seal material that functions across the expected temperature range. NASA Glenn has tested three silicone elastomers for such seal applications: two provided by Parker (S0899-50 and S0383-70) and one from Esterline (ELA-SA-401). The effects of atomic oxygen (AO), UV and electron particle radiation, and vacuum on the properties of these three elastomers were examined. Critical seal properties such as leakage, adhesion, and compression set were measured before and after simulated space exposures. The S0899-50 silicone was determined to be inadequate for extended space seal applications due to high adhesion and intolerance to UV, but both S0383-70 and ELA-SA-401 seals were adequate.

  20. Material testing of silicon carbide mirrors

    NASA Astrophysics Data System (ADS)

    Witkin, David B.; Palusinski, Iwona A.

    2009-08-01

    The Aerospace Corporation is developing a space qualification method for silicon carbide optical systems that covers material verification through system development. One of the initial efforts has been to establish testing protocols for material properties. Three different tests have been performed to determine mechanical properties of SiC: modulus of rupture, equibiaxial flexural strength and fracture toughness. Testing materials and methods have been in accordance with the respective ASTM standards. Material from four vendors has been tested to date, as part of the MISSE flight program and other programs. Data analysis has focused on the types of issues that are important when building actual components- statistical modeling of test results, understanding batch-to-batch or other source material variations, and relating mechanical properties to microstructures. Mechanical properties are needed as inputs to design trade studies and development and analysis of proof tests, and to confirm or understand the results of non-destructive evaluations of the source materials. Measuring these properties using standardized tests on a statistically valid number of samples is intended to increase confidence for purchasers of SiC spacecraft components that materials and structures will perform as intended at the highest level of reliability.

  1. Low cost silicon solar array project silicon materials task

    NASA Technical Reports Server (NTRS)

    1977-01-01

    A program was established to develop a high temperature silicon production process using existing electric arc heater technology. Silicon tetrachloride and a reductant will be injected into an arc heated mixture of hydrogen and argon. Under these high temperature conditions, a very rapid reaction is expected to occur and proceed essentially to completion, yielding silicon and gaseous sodium chloride. Techniques for high temperature separation and collection of the molten silicon will be developed using standard engineering approaches, and the salt vapor will later be electrolytically separated into its elemental constituents for recycle. Preliminary technical evaluations and economic projections indicate not only that this process appears to be feasible, but that it also has the advantages of rapid, high capacity production of good quality molten silicon at a nominal cost.

  2. Solar cell structure incorporating a novel single crystal silicon material

    DOEpatents

    Pankove, Jacques I.; Wu, Chung P.

    1983-01-01

    A novel hydrogen rich single crystal silicon material having a band gap energy greater than 1.1 eV can be fabricated by forming an amorphous region of graded crystallinity in a body of single crystalline silicon and thereafter contacting the region with atomic hydrogen followed by pulsed laser annealing at a sufficient power and for a sufficient duration to recrystallize the region into single crystal silicon without out-gassing the hydrogen. The new material can be used to fabricate semiconductor devices such as single crystal silicon solar cells with surface window regions having a greater band gap energy than that of single crystal silicon without hydrogen.

  3. Silicon material development for terrestrial solar cells. Phase of exploration

    NASA Astrophysics Data System (ADS)

    Sirtl, E.

    1983-03-01

    A material project based on a multicrystalline silicon is reported. It consists of refining the metallurgical grade silicon via hydro and pyrometallurgical processes, preparation of square shaped ingots by (inert) gas protected or open hearth casting methods, and high speed slicing, using a multiple blade slurry saw. Second generation pilot equipment was constructed. Aluminothermic reduction of quartz sand into silicon and the foil casting process were tested. It is concluded that the production of silicon thru the gaseous phase depends upon the marketing of very cheap basic material (SG-Si 10 dollar/Kg) and that the purification of metallurgical grade silicon by refining is the most promising method.

  4. A review of the silicon material task

    NASA Technical Reports Server (NTRS)

    Lutwack, R.

    1984-01-01

    The Silicon Material Task of the Flat-Plate Solar Array Project was assigned the objective of developing the technology for low-cost processes for producing polysilicon suitable for terrestrial solar-cell applications. The Task program comprised sections for process developments for semiconductor-grade and solar-cell-grade products. To provide information for deciding upon process designs, extensive investigations of the effects of impurities on material properties and the performance of cells were conducted. The silane process of the Union Carbide Corporation was carried through several stages of technical and engineering development; a pilot plant was the culmination of this effort. The work to establish silane fluidized-bed technology for a low-cost process is continuing. The advantages of the use of dichlorosilane is a siemens-type were shown by Hemlock Semiconductor Corporation. The development of other processes is described.

  5. Process feasibility study in support of silicon material task 1

    NASA Technical Reports Server (NTRS)

    Yaws, C. L.; Li, K. Y.; Hopper, J. R.; Fang, C. S.; Hansen, K. C.

    1981-01-01

    Results for process system properties, chemical engineering and economic analyses of the new technologies and processes being developed for the production of lower cost silicon for solar cells are presented. Analyses of process system properties are important for chemical materials involved in the several processes under consideration for semiconductor and solar cell grade silicon production. Major physical, thermodynamic and transport property data are reported for silicon source and processing chemical materials.

  6. Process Research on Polycrystalline Silicon Material (PROPSM)

    NASA Technical Reports Server (NTRS)

    Culik, J. S.; Wrigley, C. Y.

    1985-01-01

    Results of hydrogen-passivated polycrysalline silicon solar cell research are summarized. The short-circuit current of solar cells fabricated from large-grain cast polycrystalline silicon is nearly equivalent to that of single-crystal cells, which indicates long bulk minority-carrier diffusion length. Treatments with molecular hydrogen showed no effect on large-grain cast polycrystalline silicon solar cells.

  7. Superior radiation tolerant materials: Amorphous silicon oxycarbide

    NASA Astrophysics Data System (ADS)

    Nastasi, Michael; Su, Qing; Price, Lloyd; Colón Santana, Juan A.; Chen, Tianyi; Balerio, Robert; Shao, Lin

    2015-06-01

    We studied the radiation tolerance of amorphous silicon oxycarbide (SiOC) alloys by combining ion irradiation, X-ray diffraction (XRD) and transmission electron microscopy (TEM). The amorphous SiOC alloys thin films were grown via co-sputtering from SiO2 and SiC (amorphous phase) targets either on a surface oxidized Si (100) substrate or on a sodium chloride substrate. By controlling the sputtering rate of each target, SiOC alloys with different compositions (1:2, 1:1, 2:1 ratios) were obtained. These alloys were irradiated by 100 keV He+ ions at both room temperature and 600 °C with damage levels ranging from 1 to 20 displacements per atom (dpa). TEM characterization shows no sign of crystallization, void formation or segregation in all irradiated samples. Our findings suggest that SiOC alloys are a class of promising radiation-tolerant materials.

  8. Process Research On Polycrystalline Silicon Material (PROPSM)

    NASA Technical Reports Server (NTRS)

    Culik, J. S.; Wohlgemuth, J. H.

    1982-01-01

    Performance limiting mechanisms in polycrystalline silicon are investigated by fabricating a matrix of solar cells of various thicknesses from polycrystalline silicon wafers of several bulk resistivities. The analysis of the results for the entire matrix indicates that bulk recombination is the dominant factor limiting the short circuit current in large grain (greater than 1 to 2 mm diameter) polycrystalline silicon, the same mechanism that limits the short circuit current in single crystal silicon. An experiment to investigate the limiting mechanisms of open circuit voltage and fill factor for large grain polycrystalline silicon is designed. Two process sequences to fabricate small cells are investigated.

  9. Process Research on Polycrystalline Silicon Material (PROPSM)

    NASA Technical Reports Server (NTRS)

    Culik, J. S.

    1983-01-01

    The performance limiting mechanisms in large grain (greater than 1-2 mm in diameter) polycrystalline silicon was investigated by measuring the illuminated current voltage (I-V) characteristics of the minicell wafer set. The average short circuit current on different wafers is 3 to 14 percent lower than that of single crystal Czochralski silicon. The scatter was typically less than 3 percent. The average open circuit voltage is 20 to 60 mV less than that of single crystal silicon. The scatter in the open circuit voltage of most of the polycrystalline silicon wafers was 15 to 20 mV, although two wafers had significantly greater scatter than this value. The fill factor of both polycrystalline and single crystal silicon cells was typically in the range of 60 to 70 percent; however several polycrystalline silicon wafers have fill factor averages which are somewhat lower and have a significantly larger degree of scatter.

  10. Porous silicon as a substrate material for potentiometric biosensors

    NASA Astrophysics Data System (ADS)

    Thust, Marion; Schöning, M. J.; Frohnhoff, S.; Arens-Fischer, R.; Kordos, P.; Lüth, H.

    1996-01-01

    For the first time porous silicon has been investigated for the purpose of application as a substrate material for potentiometric biosensors operating in aqueous solutions. Porous silicon was prepared from differently doped silicon substrates by a standard anodic etching process. After oxidation, penicillinase, an enzyme sensitive to penicillin, was bound to the porous structure by physical adsorption. To characterize the electrochemical properties of the so build up penicillin biosensor, capacitance - voltage (C - V) measurements were performed on these field-effect structures.

  11. Holey Silicon as an Efficient Thermoelectric Material

    SciTech Connect

    Tang, Jinyao; Wang, Hung-Ta; Hyun Lee, Dong; Fardy, Melissa; Huo, Ziyang; Russell, Thomas P.; Yang, Peidong

    2010-09-30

    This work investigated the thermoelectric properties of thin silicon membranes that have been decorated with high density of nanoscopic holes. These ?holey silicon? (HS) structures were fabricated by either nanosphere or block-copolymer lithography, both of which are scalable for practical device application. By reducing the pitch of the hexagonal holey pattern down to 55 nm with 35percent porosity, the thermal conductivity of HS is consistently reduced by 2 orders of magnitude and approaches the amorphous limit. With a ZT value of 0.4 at room temperature, the thermoelectric performance of HS is comparable with the best value recorded in silicon nanowire system.

  12. Silicon carbide material sintered bodies manufacturing

    NASA Technical Reports Server (NTRS)

    Suzuki, K.; Shinohara, N.

    1984-01-01

    A method is described for producing a high density silicon carbide sintering substance which contains aluminum oxide. The sintering is done in CO gas atmosphere, which is kept at 2 to 20 atmospheric pressures.

  13. Electrochemistry of Silicon: Instrumentation, Science, Materials and Applications

    NASA Astrophysics Data System (ADS)

    Lehmann, Volker

    2002-04-01

    Silicon has been and will most probably continue to be the dominant material in semiconductor technology. Although the defect-free silicon single crystal is one of the best understood systems in materails science, its electrochemistry to many people is still a kind of "alchemy". This view is partly due to the interdisciplinary aspects of the topic: Physics meets chemistry at the silicon-electrolyte interface. This book gives a comprehensive overview of this important aspect of silicon technology as well as examples of applications ranging from photonic crystals to biochips. It will serve materials scientists as well as engineers involved in silicon technology as a quick reference with its more than 150 technical tables and diagrams and ca. 1000 references cited for easy access of the original literature.

  14. Method for forming fibrous silicon carbide insulating material

    DOEpatents

    Wei, George C.

    1984-01-01

    A method whereby silicon carbide-bonded SiC fiber composites are prepared from carbon-bonded C fiber composites is disclosed. Carbon-bonded C fiber composite material is treated with gaseous silicon monoxide generated from the reaction of a mixture of colloidal silica and carbon black at an elevated temperature in an argon atmosphere. The carbon in the carbon bond and fiber is thus chemically converted to SiC resulting in a silicon carbide-bonded SiC fiber composite that can be used for fabricating dense, high-strength high-toughness SiC composites or as thermal insulating materials in oxidizing environments.

  15. Method for forming fibrous silicon carbide insulating material

    DOEpatents

    Wei, G.C.

    1983-10-12

    A method whereby silicon carbide-bonded SiC fiber composites are prepared from carbon-bonded C fiber composites is disclosed. Carbon-bonded C fiber composite material is treated with gaseous silicon monoxide generated from the reaction of a mixture of colloidal silica and carbon black at an elevated temperature in an argon atmosphere. The carbon in the carbon bond and fiber is thus chemically converted to SiC resulting in a silicon carbide-bonded SiC fiber composite that can be used for fabricating dense, high-strength high-toughness SiC composites or as thermal insulating materials in oxidizing environments.

  16. Influences of p- and n-Doped Czochralski Base Material on the Performance of Silicon Based Heterojunction Solar Cells

    NASA Astrophysics Data System (ADS)

    Ziegler, Johannes; Montesdeoca-Santana, Amada; Platt, Dominik; Hohage, Stefan; Guerrero-Lemus, Ricardo; Borchert, Dietmar

    2012-10-01

    In this work we present a cell process for amorphous crystalline silicon heterojunction (SHJ) solar cells based on process steps well known in the photovoltaic industry. All amorphous silicon layers are deposited by plasma enhanced chemical vapor deposition (PECVD) in a one chamber direct plasma reactor working at a radio frequency of 13.56 MHz. The main focus of this work is to study the influence of p- and n-doped Czochralski (Cz) silicon base material with different surface morphology on the cell results of amorphous crystalline SHJ solar cells with intrinsic thin layers. Open circuit voltages Voc of up to 700 mV are obtained on n-type Cz based SHJ cells (area 100 cm2) with rough surfaces. On p-type Cz based SHJ cells open circuit voltages were limited by the minority carrier bulk lifetime of the used base material.

  17. Silicon radiation detectors: materials and applications

    SciTech Connect

    Walton, J.T.; Haller, E.E.

    1982-10-01

    Silicon nuclear radiation detectors are available today in a large variety of sizes and types. This profusion has been made possible by the ever increasing quality and diameter silicon single crystals, new processing technologies and techniques, and innovative detector design. The salient characteristics of the four basic detector groups, diffused junction, ion implanted, surface barrier, and lithium drift are reviewed along with the silicon crystal requirements. Results of crystal imperfections detected by lithium ion compensation are presented. Processing technologies and techniques are described. Two recent novel position-sensitive detector designs are discussed - one in high-energy particle track reconstruction and the other in x-ray angiography. The unique experimental results obtained with these devices are presented.

  18. Flat-plate solar array project. Volume 2: Silicon material

    NASA Technical Reports Server (NTRS)

    Lutwack, R.

    1986-01-01

    The goal of the Silicon Material Task, a part of the Flat Plate Solar Array (FSA) Project, was to develop and demonstate the technology for the low cost production of silicon of suitable purity to be used as the basic material for the manufacture of terrestrial photovoltaic solar cells. Summarized are 11 different processes for the production of silicon that were investigated and developed to varying extent by industrial, university, and Government researchers. The silane production section of the Union Carbide Corp. (UCC) silane process was developed completely in this program. Coupled with Siemens-type chemical vapor deposition reactors, the process was carried through the pilot stage. The overall UCC process involves the conversion of metallurgical-grade silicon to silane followed by decomposition of the silane to purified silicon. The other process developments are described to varying extents. Studies are reported on the effects of impurities in silicon on both silicon-material properties and on solar cell performance. These studies on the effects of impurities yielded extensive information and models for relating specific elemental concentrations to levels of deleterious effects.

  19. Process Feasibility Study in Support of Silicon Material Task 1

    NASA Technical Reports Server (NTRS)

    Li, K. Y.; Hansen, K. C.; Yaws, C. L.

    1979-01-01

    Analysis of process system properties was continued for silicon source materials under consideration for producing silicon. The following property data are reported for dichlorosilane which is involved in processing operations for silicon: critical constants, vapor pressure, heat of vaporization, heat capacity, density, surface tension, thermal conductivity, heat of formation and Gibb's free energy of formation. The properties are reported as a function of temperature to permit rapid engineering usage. The preliminary economic analysis of the process is described. Cost analysis results for the process (case A-two deposition reactors and six electrolysis cells) are presented based on a preliminary process design of a plant to produce 1,000 metric tons/year of silicon. Fixed capital investment estimate for the plant is $12.47 million (1975 dollars) ($17.47 million, 1980 dollars). Product cost without profit is 8.63 $/kg of silicon (1975 dollars)(12.1 $/kg, 1980 dollars).

  20. Process Research On Polycrystalline Silicon Material (PROPSM)

    NASA Technical Reports Server (NTRS)

    Wohlgemuth, J. H.; Culik, J. S.

    1982-01-01

    The mechanisms limiting performance in polycrystalline silicon was determined. The initial set of experiments in this task entails the fabrication of cells of various thicknesses for four different bulk resistivities between 0.1 and 10 omega-cm. The results for the first two lots are presented.

  1. Modified silicon-germanium alloys with improved performance. [thermoelectric material

    NASA Technical Reports Server (NTRS)

    Pisharody, R. K.; Garvey, L. P.

    1978-01-01

    This paper discusses the results of a program on the modification of silicon-germanium alloys by means of small extraneous material additions in order to improve their figures-of-merit. A review of the properties that constitute the figure-of-merit indicates that it is the relatively high thermal conductivity of silicon-germanium alloys that is responsible for their low values of figure-of-merit. The intent of the effort discussed in this paper is therefore the reduction of the thermal conductivity of silicon-germanium alloys by minor alloy additions and/or changes in the basic structure of the material. Because Group III and V elements are compatible with silicon and germanium, the present effort in modifying silicon-germanium alloys has concentrated on additions of gallium phosphide. A significant reduction in thermal conductivity, approximately 40 to 50 percent, has been demonstrated while the electrical properties are only slightly affected as a result. The figure-of-merit of the resultant material is enhanced over that of silicon-germanium alloys and when fully optimized is potentially better than that of any other presently available thermoelectric material.

  2. Single electron transistor with P-type sidewall spacer gates.

    PubMed

    Lee, Jung Han; Li, Dong Hua; Lee, Joung-Eob; Kang, Kwon-Chil; Kim, Kyungwan; Park, Byung-Gook

    2011-07-01

    A single-electron transistor (SET) is one of the promising solutions to overcome the scaling limit of the Metal-Oxide-Semiconductor Field Effect Transistor (MOSFET). Up to now, various kinds of SETs are being proposed and SETs with a dual gate (DG) structure using an electrical potential barrier have been demonstrated for room temperature operation. To operate DG-SETs, however, extra bias of side gates is necessary. It causes new problems that the electrode for side gates and the extra bias for electrical barrier increase the complexity in circuit design and operation power consumption, respectively. For the reason, a new mechanism using work function (WF) difference is applied to operate a SET at room temperature by three electrodes. Its structure consists of an undoped active region, a control gate, n-doped source/drain electrodes, and metal/silicide or p-type silicon side gates, and a SET with metal/silicide gates or p-type silicon gates forms tunnel barriers induced by work function between an undoped channel and grounded side gates. Via simulation, the effectiveness of the new mechanism is confirmed through various silicide materials that have different WF values. Furthermore, by considering the realistic conditions of the fabrication process, SET with p-type sidewall spacer gates was designed, and its brief fabrication process was introduced. The characteristics of its electrical barrier and the controllability of its control gate were also confirmed via simulation. Finally, a single-hole transistor with n-type sidewall spacer gates was designed. PMID:22121580

  3. Process feasibility study in support of silicon material task 1

    NASA Technical Reports Server (NTRS)

    Li, K. Y.; Hansen, K. C.; Yaws, C. L.

    1978-01-01

    Process system properties are analyzed for materials involved in the alternate processes under consideration for solar cell grade silicon. The following property data are reported for trichlorosilane: critical constants, vapor pressure, heat of vaporization, gas heat capacity, liquid heat capacity, density, surface tension, viscosity, thermal conductivity, heat of formation, and Gibb's free energy of formation. Work continued on the measurement of gas viscosity values of silicon source materials. Gas phase viscosity values for silicon tetrafluoride between 40 C and 200 C were experimentally determined. Major efforts were expended on completion of the preliminary economic analysis of the silane process. Cost, sensitivity and profitability analysis results are presented based on a preliminary process design of a plant to produce 1,000 metric tons/year of silicon by the revised process.

  4. Process feasibility study in support of silicon material, task 1

    NASA Technical Reports Server (NTRS)

    Li, K. Y.; Hansen, K. C.; Yaws, C. L.

    1979-01-01

    Analyses of process system properties were continued for materials involved in the alternate processes under consideration for semiconductor silicon. Primary efforts centered on physical and thermodynamic property data for dichlorosilane. The following property data are reported for dichlorosilane which is involved in processing operations for solar cell grade silicon: critical temperature, critical pressure, critical volume, critical density, acentric factor, vapor pressure, heat of vaporization, gas heat capacity, liquid heat capacity and density. Work was initiated on the assembly of a system to prepare binary gas mixtures of known proportions and to measure the thermal conductivity of these mixtures between 30 and 350 C. The binary gas mixtures include silicon source material such as silanes and halogenated silanes which are used in the production of semiconductor silicon.

  5. p-type transparent conducting oxides

    NASA Astrophysics Data System (ADS)

    Sheng, Su; Fang, Guojia; Li, Chun; Xu, Sheng; Zhao, Xingzhong

    2006-06-01

    The recent advance of p-type transparent conductive oxide thin films is reviewed. The focus is on p-type transparent oxide semiconductors CuAlO2, CuGaO2, CuInO2, SrCu2O2, and LaCuOCh (Ch = chalcogen). These materials and related device applications are then shown as examples. Room temperature operation of current injection emission from ultraviolet light-emitting diodes based on p-SCO/n-ZnO p-n junctions has been demonstrated. This changed with the discovery of p-type transparent conducting oxides, thereby opening up the possibility for all-oxide transparent electronics.

  6. Monolayer MoS2 Nanoribbons as a Promising Material for Both n-type and p-type Legs in Thermoelectric Generators

    NASA Astrophysics Data System (ADS)

    Arab, A.; Davydov, A. V.; Papaconstantopoulos, D. A.; Li, Q.

    2016-06-01

    First-principles calculations have been performed to study the thermoelectric properties of monolayer MoS2 armchair nanoribbons (ACNRs). The electronic behavior of nanoribbons is dominated by the presence of edge states that are dependent on the number of zigzag chains across the nanoribbon. In addition, it is found that the phonon thermal conductance of monolayer MoS2 ACNRs is smaller than monolayer films due to phonon edge scattering. This effect is more pronounced in narrower nanoribbons, which leads to a higher ZT value compared to a monolayer MoS2 sheet. The effects of sulfur vacancy and edge roughness on the thermoelectric properties of MoS2 ACNRs have also been studied. We found that edge roughness decreased ZT values compared to those of perfect nanoribbons, as its impact on electrical conductance is more severe than on phonon thermal conductance. Sulfur vacancy, however, improved ZT in some subbands. It is shown that ZT values as high as 4 for electron-doped and 3 for hole-doped nanoribbons can be achieved at T = 500 K. The ability to achieve high ZT values for both p-type and n-type nanoribbons makes monolayer MoS2 ACNR a promising candidate for future solid-state thermoelectric generators.

  7. Nanoporous delafossite CuAlO2 from inorganic/polymer double gels: a desirable high-surface-area p-type transparent electrode material.

    PubMed

    Das, Barun; Renaud, Adèle; Volosin, Alex M; Yu, Lei; Newman, Nathan; Seo, Dong-Kyun

    2015-02-01

    Nanoporous structures of a p-type semiconductor, delafossite CuAlO(2), with a high crystallinity have been fabricated through an inorganic/polymer double-gel process and characterized for the first time via Mott-Schottky measurements. The effect of the precursor concentration, calcination temperature, and atmosphere were examined to achieve high crystallinity and photoelectrochemical properties while maximizing the porosity. The optical properties of the nanoporous CuAlO(2) are in good agreement with the literature with an optical band gap of 3.9 eV, and the observed high electrical conductivity and hole concentrations conform to highly crystalline and well-sintered nanoparticles observed in the product. The Mott-Schottky plot from the electrochemical impedance spectroscopy studies indicates a flat-band potential of 0.49 V versus Ag/AgCl. It is concluded that CuAlO(2) exhibits band energies very close to those of NiO but with electrical properties very desirable in the fabrication of photoelectrochemical devices including dye-sensitized solar cells. PMID:25584858

  8. Monolayer MoS2 Nanoribbons as a Promising Material for Both n-type and p-type Legs in Thermoelectric Generators

    NASA Astrophysics Data System (ADS)

    Arab, A.; Davydov, A. V.; Papaconstantopoulos, D. A.; Li, Q.

    2016-10-01

    First-principles calculations have been performed to study the thermoelectric properties of monolayer MoS2 armchair nanoribbons (ACNRs). The electronic behavior of nanoribbons is dominated by the presence of edge states that are dependent on the number of zigzag chains across the nanoribbon. In addition, it is found that the phonon thermal conductance of monolayer MoS2 ACNRs is smaller than monolayer films due to phonon edge scattering. This effect is more pronounced in narrower nanoribbons, which leads to a higher ZT value compared to a monolayer MoS2 sheet. The effects of sulfur vacancy and edge roughness on the thermoelectric properties of MoS2 ACNRs have also been studied. We found that edge roughness decreased ZT values compared to those of perfect nanoribbons, as its impact on electrical conductance is more severe than on phonon thermal conductance. Sulfur vacancy, however, improved ZT in some subbands. It is shown that ZT values as high as 4 for electron-doped and 3 for hole-doped nanoribbons can be achieved at T = 500 K. The ability to achieve high ZT values for both p-type and n-type nanoribbons makes monolayer MoS2 ACNR a promising candidate for future solid-state thermoelectric generators.

  9. Multifunctional uranyl hybrid materials: structural diversities as a function of pH, luminescence with potential nitrobenzene sensing, and photoelectric behavior as p-type semiconductors.

    PubMed

    Song, Jian; Gao, Xue; Wang, Zhi-Nan; Li, Cheng-Ren; Xu, Qi; Bai, Feng-Ying; Shi, Zhong-Feng; Xing, Yong-Heng

    2015-09-21

    A series of uranyl-organic frameworks (UOFs), {[(UO2)2(H2TTHA)(H2O)]·4,4'-bipy·2H2O}n (1), {[(UO2)3(TTHA)(H2O)3]}n (2), and {[(UO2)5(TTHA) (HTTHA)(H2O)3]·H3O}n (3), have been obtained by the hydrothermal reaction of uranyl acetate with a flexible hexapodal ligand (1,3,5-triazine-2,4,6-triamine hexaacetic acid, H6TTHA). These compounds exhibited three distinct 3D self-assembly architectures as a function of pH by single-crystal structural analysis, although the used ligand was the same in each reaction. Surprisingly, all of the coordination modes of the H6TTHA ligand in this work are first discovered. Furthermore, the photoluminescent results showed that these compounds displayed high-sensitivity luminescent sensing functions for nitrobenzene. Additionally, the surface photovoltage spectroscopy and electric-field-induced surface photovoltage spectroscopy showed that compounds 1-3 could behave as p-type semiconductors.

  10. Process Feasibility Study in Support of Silicon Material, Task 1

    NASA Technical Reports Server (NTRS)

    Li, K. Y.; Hansen, K. C.; Yaws, C. L.

    1979-01-01

    During this reporting period, major activies were devoted to process system properties, chemical engineering and economic analyses. Analyses of process system properties was continued for materials involved in the alternate processes under consideration for solar cell grade silicon. The following property data are reported for silicon tetrafluoride: critical constants, vapor pressure, heat of varporization, heat capacity, density, surface tension, viscosity, thermal conductivity, heat of formation and Gibb's free energy of formation. Chemical engineering analysis of the BCL process was continued with primary efforts being devoted to the preliminary process design. Status and progress are reported for base case conditions; process flow diagram; reaction chemistry; material and energy balances; and major process equipment design.

  11. High temperature material interactions of thermoelectric systems using silicon germanium.

    NASA Technical Reports Server (NTRS)

    Stapfer, G.; Truscello, V. C.

    1973-01-01

    The efficient use of silicon germanium thermoelectric material for radioisotope thermoelectric generators (RTG) is achieved by operation at relatively high temperatures. The insulation technique which is most appropriate for this application uses multiple layers of molybdenum foil and astroquartz. Even so, the long term operation of these materials at elevated temperatures can cause material interaction to occur within the system. To investigate these material interactions, the Jet Propulsion Laboratory is currently testing a number of thermoelectric modules which use four silicon germanium thermoelectric couples in conjunction with the multifoil thermal insulation. The paper discusses the results of the ongoing four-couple module test program and correlates test results with those of a basic material test program.

  12. Silicone and Fluorosilicone Based Materials for Biomedical Applications

    NASA Astrophysics Data System (ADS)

    Palsule, Aniruddha S.

    The biocompatibility and the biodurability of silicones is a result of various material properties such as hydrophobicity, low surface tension, high elasticity and chemical and thermal stability. A variety of biomedical implants employ an inflatable silicone rubber balloon filled with a saline solution. Commercial examples of such a system are silicone breast implants, tissue expanders and gastric bands for obesity control. Despite the advantages, saline filled silicones systems still have a certain set of challenges that need to be addressed in order to improve the functionality of these devices and validate their use as biomaterials. The central goal of this research is to identify these concerns, design solutions and to provide a better understanding of the behavior of implantable silicones. The first problem this research focuses on is the quantification and identification of the low molecular weight silicones that are not crosslinked into the elastomeric matrix and therefore can be leached out by solvent extraction. We have developed an environmentally friendly pre-extraction technique using supercritical CO 2 and also determined the exact nature of the extractables using Gas Chromatography. We have also attempted to address the issue of an observed loss of pressure in the saline filled device during application by studying the relaxation behavior of silicone elastomer using Dynamic Mechanical Analysis and constructing long-term relaxation master curves. We have also developed a technique to develop highly hydrophobic fluorinated barrier layers for the silicone in order to prevent diffusion of water vapor across the walls of the implant. This involves a hybrid process consisting of surface modification by plasma technology followed by two different coating formulations. The first formulation employed UV curable fluorinated acrylate monomers for the coating process and the second was based on Atom Transfer Radical Polymerization (ATRP) to generate a fluorinated

  13. Porous silicon based anode material formed using metal reduction

    SciTech Connect

    Anguchamy, Yogesh Kumar; Masarapu, Charan; Deng, Haixia; Han, Yongbong; Venkatachalam, Subramanian; Kumar, Sujeet; Lopez, Herman A.

    2015-09-22

    A porous silicon based material comprising porous crystalline elemental silicon formed by reducing silicon dioxide with a reducing metal in a heating process followed by acid etching is used to construct negative electrode used in lithium ion batteries. Gradual temperature heating ramp(s) with optional temperature steps can be used to perform the heating process. The porous silicon formed has a high surface area from about 10 m.sup.2/g to about 200 m.sup.2/g and is substantially free of carbon. The negative electrode formed can have a discharge specific capacity of at least 1800 mAh/g at rate of C/3 discharged from 1.5V to 0.005V against lithium with in some embodiments loading levels ranging from about 1.4 mg/cm.sup.2 to about 3.5 mg/cm.sup.2. In some embodiments, the porous silicon can be coated with a carbon coating or blended with carbon nanofibers or other conductive carbon material.

  14. Coated silicon comprising material for protection against environmental corrosion

    NASA Technical Reports Server (NTRS)

    Hazel, Brian Thomas (Inventor)

    2009-01-01

    In accordance with an embodiment of the invention, an article is disclosed. The article comprises a gas turbine engine component substrate comprising a silicon material; and an environmental barrier coating overlying the substrate, wherein the environmental barrier coating comprises cerium oxide, and the cerium oxide reduces formation of silicate glass on the substrate upon exposure to corrodant sulfates.

  15. Low cost silicon solar array project silicon materials task: Establishment of the feasibility of a process capable of low-cost, high volume production of silane (step 1) and the pyrolysis of silane to semiconductor-grade silicon (step 2)

    NASA Technical Reports Server (NTRS)

    Breneman, W. C.; Cheung, H.; Farrier, E. G.; Morihara, H.

    1977-01-01

    A quartz fluid bed reactor capable of operating at temperatures of up to 1000 C was designed, constructed, and successfully operated. During a 30 minute experiment, silane was decomposed within the reactor with no pyrolysis occurring on the reactor wall or on the gas injection system. A hammer mill/roller-crusher system appeared to be the most practical method for producing seed material from bulk silicon. No measurable impurities were detected in the silicon powder produced by the free space reactor, using the cathode layer emission spectroscopic technique. Impurity concentration followed by emission spectroscopic examination of the residue indicated a total impurity level of 2 micrograms/gram. A pellet cast from this powder had an electrical resistivity of 35 to 45 ohm-cm and P-type conductivity.

  16. Silicon Carbide- Based Materials for Joining Silicon Carbide Composites for Fusion Energy Applications

    SciTech Connect

    Lewinsohn, Charles A. ); Jones, Russell H. ); Colombo, Paolo; Riccardi, B

    2002-12-01

    This paper describes issues related to using silicon carbide derived from inorganic polymer precursors for joining silicon carbide composites for fusion energy applications. Evolution of gases and shrinkage during processing are identified as critical processes that may control the presence of strength limiting flaws and residual stresses. Precursor composition and structure effect the amount of gaseous species evolved during processing, chemical compatibility with substrates, and processing environments. Results from the literature and from the authors' investigations are used to illustrate the use of polymer derived material for joining.

  17. P-type transparent conducting oxides

    NASA Astrophysics Data System (ADS)

    Stauber, Renaud Emmanuel

    2003-10-01

    Transparent conductors have important energy and general technology applications as transparent front contacts to photovoltaic cells, electrochromic windows and flat panel displays. Conventional transparent conductors such as SnO 2 are n-type (electron) conductors. As yet, there are no comparable, p-type (hole) analogues. However, researchers have recently reported that CuAlO2, N:ZnO and SrCu2O2 films (among others) may be viable p-type transparent conductors, albeit with carrier concentrations three orders of magnitude lower than n-type SnO2. If these materials could be more effectively hole-doped, they would enhance existing technologies and enable new photovoltaic designs through improved transparent contacts to p-type materials and as possible heterojunction partners. This thesis describes our program for growing and evaluating CuAlO2, ZnO and SrCu 2O2 thin films for use as p-type transparent conductors. Our work on CuAlO2 focused on the optimization of crystal growth and transport properties by pulsed laser deposition (PLD) and sputtering. The films with the best surface morphology and phase-purity were formed by annealing precursors that had been sputtered at room temperature at 940°C in 10T of O2. The phase-purity and transparency of these films is higher than any reported in the literature, and we provided the first experimental confirmation of Kawazoe's work on CuAlO2 [1] as a potential p-type conductor. We also attempted to make transparent electrically conductive p-type ZnO by PLD and sputtering using N2, N2O, NO, and NH 3 gases. Expanding on the work of Kawai and coworkers [2,3], we used an ion source, rather than an ECR source in the PLD chamber to dissociate N2O gas, and explored the use of aluminum in addition to gallium as potential co-dopants. The most promising results have been obtained with DC reactive sputtering of un-doped zinc metal targets in NO or NH3. A three to six order of magnitude reduction in n-type conductivity occurred when 2% of

  18. Dynamic viscoelastic properties of experimental silicone soft lining materials.

    PubMed

    Santawisuk, Wallapat; Kanchanavasita, Widchaya; Sirisinha, Chakrit; Harnirattisai, Choltacha

    2010-08-01

    The purpose of this study was to evaluate the dynamic viscoelastic properties of experimental silicone soft lining materials, Silastic MDX 4-4210 reinforced with silica fillers. Storage modulus (E'), loss modulus (E") and damping factor (tan delta) were determined using a dynamic mechanical analyzer under a deformation strain level of 0.27% at test frequency and a temperature range of 1 Hz and 0 to 60 degrees C, respectively. The degree of silica dispersion was also studied using a field emission scanning electron microscopy (FE-SEM). One-way ANOVA and Tukey's HSD test results indicated that the prepared silicone elastomers provided a significantly greater damping factor, but less storage modulus than GC Reline Soft and Tokuyama Sofreliner Tough (p<0.001). The storage moduli, loss moduli and damping factor of the experimental silicone elastomers increased with increasing amounts of fumed silica. In conclusion, the experimental silicone elastomers revealed acceptable dynamic viscoelastic properties to be used as denture soft lining materials.

  19. TOPICAL REVIEW: New crystalline silicon ribbon materials for photovoltaics

    NASA Astrophysics Data System (ADS)

    Hahn, G.; Schönecker, A.

    2004-12-01

    The objective of this article is to review, in relation to photovoltaic applications, the current status of crystalline silicon ribbon technologies as an alternative to technologies based on wafers originating from ingots. Increased wafer demand, the foreseeable silicon feedstock shortage, and the need for a substantial module cost reduction are the main issues that must be faced in the booming photovoltaic market. Ribbon technologies make excellent use of silicon, as wafers are crystallized directly from the melt at the desired thickness and no kerf losses occur. Therefore, they offer a high potential for significantly reducing photovoltaic electricity costs as compared to technology based on wafers cut from ingots. However, the defect structure present in the ribbon silicon wafers can limit material quality and cell efficiency. We will review the most successful of the ribbon techniques already used in large scale production or currently in the pilot demonstration phase, with special emphasis on the defects incorporated during crystal growth. Because of the inhomogeneous distribution of defects, mapped characterization techniques have to be applied. Al and P gettering studies give an insight into the complex interaction of defects in the multicrystalline materials as the gettering efficiency is influenced by the state of the chemical bonding of the metal atoms. The most important technique for improvement of carrier lifetimes is hydrogenation, whose kinetics are strongly influenced by oxygen and carbon concentrations present in the material. The best cell efficiencies for laboratory-type (17%-18% cell area: 4 cm2) as well as industrial-type (15%-16% cell area: {\\ge } 80~{\\mathrm {cm^{2}}} ) ribbon silicon solar cells are in the same range as for standard wafers cut from ingots. A substantial cost reduction therefore seems achievable, although the most promising techniques need to be improved.

  20. Electrical test structures replicated in silicon-on-insulator material

    SciTech Connect

    Cresswell, M.W.; Ghoshtagore, R.N.; Allen, R.A.; Linholm, L.W.; Villarrubia, J.S.; Sniegowski, J.J.

    1996-02-27

    Measurements of the linewidths of submicrometer features made by different metrology techniques have frequently been characterized by differences of up to 90 nm. The purpose of the work reported here is to address the special difficulties that this phenomenon presents to the certification of reference materials for the calibration of linewidth-measurement instruments. Accordingly, a new test structure has been designed, fabricated, and undergone preliminary tests. Its distinguishing characteristics are assured cross-sectional profile geometries with known side-wall slopes, surface planarity, and compositional uniformity when it is formed in mono-crystalline material at selected orientations to the crystal lattice. To allow the extraction of electrical linewidth, the structure is replicated in a silicon film of uniform conductivity which is separated from the silicon substrate by a buried oxide layer. The utilization of a Silicon-On-Insulator (SKI) substrate further allows the selective removal of substrate material from local regions below the reference features, thus facilitating measurements by optical and electron-beam transmission microscopy. The combination of planar feature surfaces having known side-wall slopes is anticipated to eliminate factors which are believed to be responsible for methods divergence in linewidth measurements, a capability which is a prerequisite for reliable certification of the linewidths of features on reference materials.

  1. High ZT in p-type (PbTe)1-2x(PbSe)x(PbS)x thermoelectric materials.

    PubMed

    Korkosz, Rachel J; Chasapis, Thomas C; Lo, Shih-han; Doak, Jeff W; Kim, Yoon Jun; Wu, Chun-I; Hatzikraniotis, Euripidis; Hogan, Timothy P; Seidman, David N; Wolverton, Chris; Dravid, Vinayak P; Kanatzidis, Mercouri G

    2014-02-26

    Lead chalcogenide thermoelectric systems have been shown to reach record high figure of merit values via modification of the band structure to increase the power factor or via nanostructuring to reduce the thermal conductivity. Recently, (PbTe)1-x(PbSe)x was reported to reach high power factors via a delayed onset of interband crossing. Conversely, the (PbTe)1-x(PbS)x was reported to achieve low thermal conductivities arising from extensive nanostructuring. Here we report the thermoelectric properties of the pseudoternary 2% Na-doped (PbTe)1-2x(PbSe)x(PbS)x system. The (PbTe)1-2x(PbSe)x(PbS)x system is an excellent platform to study phase competition between entropically driven atomic mixing (solid solution behavior) and enthalpy-driven phase separation. We observe that the thermoelectric properties of the PbTe-PbSe-PbS 2% Na doped are superior to those of 2% Na-doped PbTe-PbSe and PbTe-PbS, respectively, achieving a ZT ≈2.0 at 800 K. The material exhibits an increased the power factor by virtue of valence band modification combined with a very reduced lattice thermal conductivity deriving from alloy scattering and point defects. The presence of sulfide ions in the rock-salt structure alters the band structure and creates a plateau in the electrical conductivity and thermopower from 600 to 800 K giving a power factor of 27 μW/cmK(2). The very low total thermal conductivity values of 1.1 W/m·K of the x = 0.07 composition is accounted for essentially by phonon scattering from solid solution defects rather than the assistance of endotaxial nanostructures.

  2. Process research on non-CZ silicon material

    NASA Technical Reports Server (NTRS)

    1982-01-01

    High risk, high payoff research areas associated with he process for producing photovoltaic modules using non-CZ sheet material are investigated. All investigations are being performed using dendritic web silicon, but all processes are directly applicable to other ribbon forms of sheet material. The technical feasibility of forming front and back junctions in non-CZ silicon using liquid dopant techniques was determined. Numerous commercially available liquid phosphorus and boron dopant solutions are investigated. Temperature-time profiles to achieve N(+) and P(+) sheet resistivities of 60 + or - 10 and 40 + or - s10 ohms per square centimeter respectively are established. A study of the optimal method of liquid dopant application is performed. The technical feasibility of forming a liquid applied diffusion mask to replace the more costly chemical vapor deposited SiO2 diffusion mask was also determined.

  3. Amorphous and microcrystalline silicon technology--1997. Materials Research Society symposium proceedings, Volume 467

    SciTech Connect

    Wagner, S.; Hack, M.; Schiff, E.A.; Schropp, R.; Shimizu, I.

    1997-07-01

    This book was divided into the following parts: Staebler-Wronski and Fundamental Defect Studies in Amorphous Silicon; The Story of Hydrogen in Amorphous Silicon; Photoelectric Properties of Amorphous Silicon; Deposition and Properties of Microcrystalline Silicon; Deposition Studies for Amorphous Silicon and Related Materials; Solar Cells; Thin-Film Transistors; and Sensors and Novel Device Concepts. Separate abstracts were prepared for most of the papers in the volume.

  4. Silicon Composite Anode Materials for Lithium Ion Batteries Based on Carbon Cryogels and Carbon Paper

    NASA Technical Reports Server (NTRS)

    Woodworth, James; Baldwin, Richard; Bennett, William

    2010-01-01

    A variety of materials are under investigation for use as anode materials in lithium-ion batteries, of which, the most promising are those containing silicon. One such material is a composite formed via the dispersion of silicon in a resorcinol-formaldehyde (RF) gel followed by pyrolysis. Two silicon-carbon composite materials, carbon microspheres and nanofoams produced from nano-phase silicon impregnated RF gel precursors have been synthesized and investigated. Carbon microspheres are produced by forming the silicon-containing RF gel into microspheres whereas carbon nanofoams are produced by impregnating carbon fiber paper with the silicon containing RF gel to create a free standing electrode. Both materials have demonstrated their ability to function as anodes and utilize the silicon present in the material. Stable reversible capacities above 400 mAh/g for the bulk material and above 1000 mAh/g of Si have been observed.

  5. Carbon Cryogel and Carbon Paper-Based Silicon Composite Anode Materials for Lithium-Ion Batteries

    NASA Technical Reports Server (NTRS)

    Woodworth, James; Baldwin, Richard; Bennett, William

    2010-01-01

    A variety of materials are under investigation for use as anode materials in lithium-ion batteries, of which, the most promising are those containing silicon. 6 One such material is a composite formed via the dispersion of silicon in a resorcinol-formaldehyde (RF) gel followed by pyrolysis. Two silicon-carbon composite materials, carbon microspheres and nanofoams produced from nano-phase silicon impregnated RF gel precursors have been synthesized and investigated. Carbon microspheres are produced by forming the silicon-containing RF gel into microspheres whereas carbon nano-foams are produced by impregnating carbon fiber paper with the silicon containing RF gel to create a free standing electrode. 1-5 Both materials have demonstrated their ability to function as anodes and utilize the silicon present in the material. Stable reversible capacities above 400 mAh/g for the bulk material and above 1000 mAh/g of Si have been observed.

  6. Materials Chemistry and Performance of Silicone-Based Replicating Compounds.

    SciTech Connect

    Brumbach, Michael T.; Mirabal, Alex James; Kalan, Michael; Trujillo, Ana B; Hale, Kevin

    2014-11-01

    Replicating compounds are used to cast reproductions of surface features on a variety of materials. Replicas allow for quantitative measurements and recordkeeping on parts that may otherwise be difficult to measure or maintain. In this study, the chemistry and replicating capability of several replicating compounds was investigated. Additionally, the residue remaining on material surfaces upon removal of replicas was quantified. Cleaning practices were tested for several different replicating compounds. For all replicating compounds investigated, a thin silicone residue was left by the replica. For some compounds, additional inorganic species could be identified in the residue. Simple solvent cleaning could remove some residue.

  7. Silicon nitride/silicon carbide composite densified materials prepared using composite powders

    DOEpatents

    Dunmead, Stephen D.; Weimer, Alan W.; Carroll, Daniel F.; Eisman, Glenn A.; Cochran, Gene A.; Susnitzky, David W.; Beaman, Donald R.; Nilsen, Kevin J.

    1997-07-01

    Prepare silicon nitride-silicon carbide composite powders by carbothermal reduction of crystalline silica powder, carbon powder and, optionally, crystalline silicon nitride powder. The crystalline silicon carbide portion of the composite powders has a mean number diameter less than about 700 nanometers and contains nitrogen. The composite powders may be used to prepare sintered ceramic bodies and self-reinforced silicon nitride ceramic bodies.

  8. Proceedings of the Flat-Plate Solar Array Workshop on the Science of Silicon Material Preparation

    NASA Technical Reports Server (NTRS)

    1983-01-01

    Several areas of silicon material preparation were addressed including silicon production and purity, thermodynamics, kinetics, mechanisms, particle formation and growth, deposition in fluidized bed reactors, and chemical vapor deposition. Twenty-two papers were presented.

  9. Process research of non-CZ silicon material

    NASA Technical Reports Server (NTRS)

    1983-01-01

    High risk, high payoff research areas associated with the Westinghouse process for producing photovoltaic modules using non- CZ sheet material were investigated. All work was performed using dendritic web silicon. The following tasks are discussed and associated technical results are given: (1) determining the technical feasibility of forming front and back junctions in non-CT silicon using dopant techniques; (2) determining the feasibility of forming a liquid applied diffusion mask to replace the more costly chemical vapor deposited SiO2 diffusion mask; (3) determining the feasibility of applying liquid anti-reflective solutions using meniscus coating equipment; (4) studying the production of uniform, high efficiency solar cells using ion implanation junction formation techniques; and (5) quantifying cost improvements associated with process improvements.

  10. Development and evaluation of die and container materials. Low cost silicon solar array project

    NASA Technical Reports Server (NTRS)

    Wills, R. R.; Niesx, D. E.

    1979-01-01

    Specific compositions of high purity silicon aluminum oxynitride (Sialon) and silicon beryllium oxynitride (Sibeon) solid solutions were shown to be promising refractory materials for handling and manipulating solar grade silicon into silicon ribbon. Evaulation of the interaction of these materials in contact with molten silicon indicated that solid solutions based upon beta-Si3N4 were more stable than those based on Si2N2O. Sibeon was more resistant to molten silicon attack than Sialon. Both materials should preferably be used in an inert atmosphere rather than under vacuum conditions because removal of oxygen from the silicon melt occurs as SiO enhances the dissolution of aluminum and beryllium. The wetting angles of these materials were low enough for these materials to be considered as both die and container materials.

  11. Nonmetallic materials handbook. Volume 2: Epoxy and silicone materials

    NASA Technical Reports Server (NTRS)

    Podlaseck, S. E.

    1982-01-01

    Chemical and physical property test data obtained during qualification and receiving inspection testing of nonmetallic materials for the Viking Mars Lander program is presented. Thermochemical data showing degradation as a function of temperature from room temperature through 773 K is included. These data include activation energies for thermal degradation, rate constants, and exo- and/or endotherms. Thermal degradations carried out under vacuum include mass spectral data taken simultaneously during the decomposition. Many materials have supporting data such as condensation rates of degassed products and isothermal weight loss. Changes in mechanical, electrical, and thermal properties after exposure to 408 K in nitrogen for times ranging from 380 to 570 hours are included for many materials.

  12. P-type electronic and thermal transport properties of Mg2Sn1-xSix

    NASA Astrophysics Data System (ADS)

    Kim, Sunphil; Wiendlocha, Bartlomiej; Heremans, Joseph P.

    2013-03-01

    P-type Mg2Sn doped with various acceptors(1)(2) has been studied as a potential thermoelectric material. Because of its narrow band gap and high lattice thermal conductivity, the zT values of the binary compound are limited: zTmax reported is 0.3(3). In this work, we synthesize and characterize p-type-doped Mg2Sn1-xSix with various acceptors. Silicon is added in order to widen the band gap and scatter the phonons. The conduction band degeneracy that yields excellent zT in n-type material in the Mg2Sn1-xSix alloy system unfortunately does not apply to p-type material. Thermomagnetic and galvanomagnetic properties (electrical resistivity, Seebeck, Hall, and Nernst coefficients) are measured, along with thermal conductivity and band gap measurements. Finally, zT values are reported. (1) H. Y. Chen et al. Journal of Electronic Materials, Vol. 38, No. 7, 2009 (2) S. Choi et al. Journal of Electronic Materials, Vol. 41, No. 6, 2012 (3) H. Y. Chen et al. Phys. Status Solidi A 207, No. 11, 2523-2531 (2010) The work is supported by the joint NSF/DOE program on thermoelectrics, NSF-CBET-1048622

  13. Dual-beam laser thermal processing of silicon photovoltaic materials

    NASA Astrophysics Data System (ADS)

    Simonds, Brian J.; Teal, Anthony; Zhang, Tian; Hadler, Josh; Zhou, Zibo; Varlamov, Sergey; Perez-Würfl, Ivan

    2016-03-01

    We have developed an all-laser processing technique by means of two industrially-relevant continuous-wave fiber lasers operating at 1070 nm. This approach is capable of both substrate heating with a large defocused beam and material processing with a second scanned beam, and is suitable for a variety of photovoltaic applications. We have demonstrated this technique for rapid crystallization of thin film (~10 μm) silicon on glass, which is a low cost alternative to wafer-based solar cells. We have also applied this technique to wafer silicon to control dopant diffusion at the surface region where the focused line beam rapidly melts the substrate that then regrows epitaxially. Finite element simulations have been used to model the melt depth as a function of preheat temperature and line beam power. This process is carried out in tens of seconds for an area approximately 10 cm2 using only about 1 kW of total optical power and is readily scalable. In this paper, we will discuss our results with both c-Si wafers and thin-film silicon.

  14. P-type transparent conducting oxides.

    PubMed

    Zhang, Kelvin H L; Xi, Kai; Blamire, Mark G; Egdell, Russell G

    2016-09-28

    Transparent conducting oxides constitute a unique class of materials combining properties of electrical conductivity and optical transparency in a single material. They are needed for a wide range of applications including solar cells, flat panel displays, touch screens, light emitting diodes and transparent electronics. Most of the commercially available TCOs are n-type, such as Sn doped In2O3, Al doped ZnO, and F doped SnO2. However, the development of efficient p-type TCOs remains an outstanding challenge. This challenge is thought to be due to the localized nature of the O 2p derived valence band which leads to difficulty in introducing shallow acceptors and large hole effective masses. In 1997 Hosono and co-workers (1997 Nature 389 939) proposed the concept of 'chemical modulation of the valence band' to mitigate this problem using hybridization of O 2p orbitals with close-shell Cu 3d (10) orbitals. This work has sparked tremendous interest in designing p-TCO materials together with deep understanding the underlying materials physics. In this article, we will provide a comprehensive review on traditional and recently emergent p-TCOs, including Cu(+)-based delafossites, layered oxychalcogenides, nd (6) spinel oxides, Cr(3+)-based oxides (3d (3)) and post-transition metal oxides with lone pair state (ns (2)). We will focus our discussions on the basic materials physics of these materials in terms of electronic structures, doping and defect properties for p-type conductivity and optical properties. Device applications based on p-TCOs for transparent p-n junctions will also be briefly discussed.

  15. P-type transparent conducting oxides

    NASA Astrophysics Data System (ADS)

    Zhang, Kelvin H. L.; Xi, Kai; Blamire, Mark G.; Egdell, Russell G.

    2016-09-01

    Transparent conducting oxides constitute a unique class of materials combining properties of electrical conductivity and optical transparency in a single material. They are needed for a wide range of applications including solar cells, flat panel displays, touch screens, light emitting diodes and transparent electronics. Most of the commercially available TCOs are n-type, such as Sn doped In2O3, Al doped ZnO, and F doped SnO2. However, the development of efficient p-type TCOs remains an outstanding challenge. This challenge is thought to be due to the localized nature of the O 2p derived valence band which leads to difficulty in introducing shallow acceptors and large hole effective masses. In 1997 Hosono and co-workers (1997 Nature 389 939) proposed the concept of ‘chemical modulation of the valence band’ to mitigate this problem using hybridization of O 2p orbitals with close-shell Cu 3d 10 orbitals. This work has sparked tremendous interest in designing p-TCO materials together with deep understanding the underlying materials physics. In this article, we will provide a comprehensive review on traditional and recently emergent p-TCOs, including Cu+-based delafossites, layered oxychalcogenides, nd 6 spinel oxides, Cr3+-based oxides (3d 3) and post-transition metal oxides with lone pair state (ns 2). We will focus our discussions on the basic materials physics of these materials in terms of electronic structures, doping and defect properties for p-type conductivity and optical properties. Device applications based on p-TCOs for transparent p-n junctions will also be briefly discussed.

  16. P-type transparent conducting oxides.

    PubMed

    Zhang, Kelvin H L; Xi, Kai; Blamire, Mark G; Egdell, Russell G

    2016-09-28

    Transparent conducting oxides constitute a unique class of materials combining properties of electrical conductivity and optical transparency in a single material. They are needed for a wide range of applications including solar cells, flat panel displays, touch screens, light emitting diodes and transparent electronics. Most of the commercially available TCOs are n-type, such as Sn doped In2O3, Al doped ZnO, and F doped SnO2. However, the development of efficient p-type TCOs remains an outstanding challenge. This challenge is thought to be due to the localized nature of the O 2p derived valence band which leads to difficulty in introducing shallow acceptors and large hole effective masses. In 1997 Hosono and co-workers (1997 Nature 389 939) proposed the concept of 'chemical modulation of the valence band' to mitigate this problem using hybridization of O 2p orbitals with close-shell Cu 3d (10) orbitals. This work has sparked tremendous interest in designing p-TCO materials together with deep understanding the underlying materials physics. In this article, we will provide a comprehensive review on traditional and recently emergent p-TCOs, including Cu(+)-based delafossites, layered oxychalcogenides, nd (6) spinel oxides, Cr(3+)-based oxides (3d (3)) and post-transition metal oxides with lone pair state (ns (2)). We will focus our discussions on the basic materials physics of these materials in terms of electronic structures, doping and defect properties for p-type conductivity and optical properties. Device applications based on p-TCOs for transparent p-n junctions will also be briefly discussed. PMID:27459942

  17. P-type transparent conducting oxides

    NASA Astrophysics Data System (ADS)

    Zhang, Kelvin H. L.; Xi, Kai; Blamire, Mark G.; Egdell, Russell G.

    2016-09-01

    Transparent conducting oxides constitute a unique class of materials combining properties of electrical conductivity and optical transparency in a single material. They are needed for a wide range of applications including solar cells, flat panel displays, touch screens, light emitting diodes and transparent electronics. Most of the commercially available TCOs are n-type, such as Sn doped In2O3, Al doped ZnO, and F doped SnO2. However, the development of efficient p-type TCOs remains an outstanding challenge. This challenge is thought to be due to the localized nature of the O 2p derived valence band which leads to difficulty in introducing shallow acceptors and large hole effective masses. In 1997 Hosono and co-workers (1997 Nature 389 939) proposed the concept of ‘chemical modulation of the valence band’ to mitigate this problem using hybridization of O 2p orbitals with close-shell Cu 3d 10 orbitals. This work has sparked tremendous interest in designing p-TCO materials together with deep understanding the underlying materials physics. In this article, we will provide a comprehensive review on traditional and recently emergent p-TCOs, including Cu+-based delafossites, layered oxychalcogenides, nd 6 spinel oxides, Cr3+-based oxides (3d 3) and post-transition metal oxides with lone pair state (ns 2). We will focus our discussions on the basic materials physics of these materials in terms of electronic structures, doping and defect properties for p-type conductivity and optical properties. Device applications based on p-TCOs for transparent p–n junctions will also be briefly discussed.

  18. Method to prevent recession loss of silica and silicon-containing materials in combustion gas environments

    DOEpatents

    Brun, Milivoj Konstantin; Luthra, Krishan Lal

    2003-01-01

    While silicon-containing ceramics or ceramic composites are prone to material loss in combustion gas environments, this invention introduces a method to prevent or greatly reduce the thickness loss by injecting directly an effective amount, generally in the part per million level, of silicon or silicon-containing compounds into the combustion gases.

  19. Thermoelectric generation device based on p-type Bi0.4Sb1.6Te3 and n-type Bi2Se0.6Te2.4 bulk materials prepared by solid state microwave synthesis

    NASA Astrophysics Data System (ADS)

    Kadhim, A.; Hmood, A.; Abu Hassan, H.

    2013-07-01

    This study reports on the fabrication of a chalcogen-based thermoelectric power generation (TEG) device using p-type Bi0.4Sb1.6Te3 and n-type Bi2Se0.6Te2.4 bulk thermoelectric materials. The microstructure of the samples was characterized by scanning electron microscope (SEM). The phase composition of the powders was characterized by X-ray diffraction (XRD), revealing a rhombohedral structure. The thermoelectric (TE) properties such as the Seebeck coefficient (S) and the electrical conductivity (σ) of the resulting alloys were studied in the temperature range of 300-523 K. The power factor (Pfactor) for a Bi0.4Sb1.6Te3 as p-type sample was found to be 4.96 mW/mK2 at 373 K, whereas 2.22 mW/mK2 was obtained at 383 K for a Bi2Se0.6Te2.4 as n-type sample. Electrical power generation characteristics such as high open circuit voltage (Voc) and maximum output power (Pmax) were monitored by changing the temperature conditions required to generate maximum power. The significance of the resistances including the internal resistance (Rin) and contact resistance (RC) between legs and electrodes, are discussed. The maximum output power obtained with the 9 p-n couples device was 39.4 mW under the thermal condition of TH=523 K hot side temperature and ΔT=184 K temperature difference.

  20. Mechanical and Electrical Properties of p-type Bi0.4Sb1.6Te3 and n-type Bi2Se0.6Te2.4 Bulk Material for Thermoelectric Applications

    NASA Astrophysics Data System (ADS)

    Kadhim, A.; Hmood, A.; Hassan, H. A.

    2013-04-01

    This study reports on the fabrication of a chalcogen-based thermoelectric power generation (TEG) device using p-type Bi0.4Sb1.6Te3 and n-type Bi2Se0.6Te2.4 bulk thermoelectric materials. The microstructure of the samples was characterized by field emission scanning electron microscopy (FESEM). The phase composition of the powders was characterized by X-ray diffraction (XRD), revealing a rhombohedral structure. The thermoelectric (TE) properties such as Seebeck coefficient (S) and the electrical conductivity (σ) of the resulting alloys were studied in the temperature range of 300 K to 523 K. The power factor (Pfactor) for a Bi0.4Sb1.6Te3 as p-type sample was found to be 4.96 mW/mK2 at 373 K, whereas 2.22 mW/mK2 was obtained at 383 K for a Bi2Se0.6Te2.4 as n-type sample. Electrical power generation characteristics such as high open circuit voltage (Voc) and maximum output power (Pmax) were monitored by changing the temperature conditions required to generate maximum power. The significance of the resistances including the internal resistance (Rin) and contact resistance (RC) between legs and electrodes, are discussed. The maximum output power obtained with the 9 p-n couples device was 39.4 mW under the thermal condition of TH = 523 K hot side temperature and ΔT = 184 K temperature difference.

  1. Influence of Chemical Composition and Structure in Silicon Dielectric Materials on Passivation of Thin Crystalline Silicon on Glass.

    PubMed

    Calnan, Sonya; Gabriel, Onno; Rothert, Inga; Werth, Matteo; Ring, Sven; Stannowski, Bernd; Schlatmann, Rutger

    2015-09-01

    In this study, various silicon dielectric films, namely, a-SiOx:H, a-SiNx:H, and a-SiOxNy:H, grown by plasma enhanced chemical vapor deposition (PECVD) were evaluated for use as interlayers (ILs) between crystalline silicon and glass. Chemical bonding analysis using Fourier transform infrared spectroscopy showed that high values of oxidant gases (CO2 and/or N2), added to SiH4 during PECVD, reduced the Si-H and N-H bond density in the silicon dielectrics. Various three layer stacks combining the silicon dielectric materials were designed to minimize optical losses between silicon and glass in rear side contacted heterojunction pn test cells. The PECVD grown silicon dielectrics retained their functionality despite being subjected to harsh subsequent processing such as crystallization of the silicon at 1414 °C or above. High values of short circuit current density (Jsc; without additional hydrogen passivation) required a high density of Si-H bonds and for the nitrogen containing films, additionally, a high N-H bond density. Concurrently high values of both Jsc and open circuit voltage Voc were only observed when [Si-H] was equal to or exceeded [N-H]. Generally, Voc correlated with a high density of [Si-H] bonds in the silicon dielectric; otherwise, additional hydrogen passivation using an active plasma process was required. The highest Voc ∼ 560 mV, for a silicon acceptor concentration of about 10(16) cm(-3), was observed for stacks where an a-SiOxNy:H film was adjacent to the silicon. Regardless of the cell absorber thickness, field effect passivation of the buried silicon surface by the silicon dielectric was mandatory for efficient collection of carriers generated from short wavelength light (in the vicinity of the glass-Si interface). However, additional hydrogen passivation was obligatory for an increased diffusion length of the photogenerated carriers and thus Jsc in solar cells with thicker absorbers.

  2. Silicon Nanowire Fabric as a Lithium Ion Battery Electrode Material

    SciTech Connect

    Chockla, Aaron M.; Harris, Justin T.; Akhavan, Vahid A.; Bogart, Timothy D.; Holmberg, Vincent C.; Steinhagen, Chet; Mullins, C. Buddie; Stevenson, Keith J.; Korgel, Brian A.

    2011-11-09

    A nonwoven fabric with paperlike qualities composed of silicon nanowires is reported. The nanowires, made by the supercritical-fluid–liquid–solid process, are crystalline, range in diameter from 10 to 50 nm with an average length of >100 μm, and are coated with a thin chemisorbed polyphenylsilane shell. About 90% of the nanowire fabric volume is void space. Thermal annealing of the nanowire fabric in a reducing environment converts the polyphenylsilane coating to a carbonaceous layer that significantly increases the electrical conductivity of the material. This makes the nanowire fabric useful as a self-supporting, mechanically flexible, high-energy-storage anode material in a lithium ion battery. Anode capacities of more than 800 mA h g{sup –1} were achieved without the addition of conductive carbon or binder.

  3. Process feasibility study in support of silicon material task 1

    NASA Technical Reports Server (NTRS)

    Fang, C. S.; Hansen, K. C.; Miller, J. W., Jr.; Yaws, C. L.

    1978-01-01

    Initial results for gas thermal conductivity of silicon tetrafluoride and trichlorosilane are reported in respective temperature ranges of 25 to 400 C and 50 to 400 C. For chemical engineering analyses, the preliminary process design for the original silane process of Union Carbide was completed for Cases A and B, Regular and Minimum Process Storage. Included are raw material usage, utility requirements, major process equipment lists, and production labor requirements. Because of the large differences in surge tankage between major unit operations the fixed capital investment varied from $19,094,000 to $11,138,000 for Cases A and B, respectively. For the silane process the original flowsheet was revised for a more optimum arrangement of major equipment, raw materials and operating conditions. The initial issue of the revised flowsheet (Case C) for the silane process indicated favorable cost benefits over the original scheme.

  4. Polycrystalline silicon material availability and market pricing outlook study for 1980 to 88: January 1983 update

    NASA Technical Reports Server (NTRS)

    Costogue, E.; Pellin, R.

    1983-01-01

    Photovoltaic solar cell arrays which convert solar energy into electrical energy can become a cost effective, alternative energy source provided that an adequate supply of low priced materials and automated fabrication techniques are available. Presently, silicon is the most promising cell material for achieving the near term cost goals of the Photovoltaics Program. Electronic grade silicon is produced primarily for the semiconductor industry with the photovoltaic industry using, in most cases, the production rejects of slightly lower grade material. Therefore, the future availability of adequate supplies of low cost silicon is one of the major concerns of the Photovoltaic Program. The supply outlook for silicon with emphasis on pricing is updated and is based primarily on an industry survey conducted by a JPL consultant. This survey included interviews with polycrystalline silicon manufacturers, a large cross section of silicon users and silicon solar cell manufacturers.

  5. Silicon material technology status. [assessment for electronic and photovoltaic applications

    NASA Technical Reports Server (NTRS)

    Lutwack, R.

    1983-01-01

    Silicon has been the basic element for the electronic and photovoltaic industries. The use of silicon as the primary element for terrestrial photovoltaic solar arrays is projected to continue. The reasons for this projection are related to the maturity of silicon technology, the ready availability of extremely pure silicon, the performance of silicon solar cells, and the considerable present investment in technology and manufacturing facilities. The technologies for producing semiconductor grade silicon and, to a lesser extent, refined metallurgical grade silicon are considered. It is pointed out that nearly all of the semiconductor grade silicon is produced by processes based on the Siemens deposition reactor, a technology developed 26 years ago. The state-of-the-art for producing silicon by this process is discussed. It is expected that efforts to reduce polysilicon process costs will continue.

  6. Investigation of epitaxial silicon layers as a material for radiation hardened silicon detectors

    SciTech Connect

    Li, Z.; Eremin, V.; Ilyashenko, I.; Ivanov, A.; Verbitskaya, E.; CERN RD-48 ROSE Collaboration

    1997-12-01

    Epitaxial grown thick layers ({ge} 100 micrometers) of high resistivity silicon (Epi-Si) have been investigated as a possible candidate of radiation hardened material for detectors for high-energy physics. As grown Epi-Si layers contain high concentration (up to 2 {times} 10{sup 12} cm{sup {minus}3}) of deep levels compared with that in standard high resistivity bulk Si. After irradiation of test diodes by protons (E{sub p} = 24 GeV) with a fluence of 1.5 {times} 10{sup 11} cm{sup {minus}2}, no additional radiation induced deep traps have been detected. A reasonable explanation is that there is a sink of primary radiation induced defects (interstitial and vacancies), possibly by as-grown defects, in epitaxial layers. The ``sinking`` process, however, becomes non-effective at high radiation fluences (10{sup 14} cm{sup {minus}2}) due to saturation of epitaxial defects by high concentration of radiation induced ones. As a result, at neutron fluence of 1 {times} 10{sup 14} cm{sup {minus}2} the deep level spectrum corresponds to well-known spectrum of radiation induced defects in high resistivity bulk Si. The net effective concentration in the space charge region equals to 3 {times} 10{sup 12} cm{sup {minus}3} after 3 months of room temperature storage and reveals similar annealing behavior for epitaxial as compared to bulk silicon.

  7. Resistivity measurements on the neutron irradiated detector grade silicon materials

    SciTech Connect

    Li, Zheng

    1993-11-01

    Resistivity measurements under the condition of no or low electrical field (electrical neutral bulk or ENB condition) have been made on various device configurations on detector grade silicon materials after neutron irradiation. Results of the measurements have shown that the ENB resistivity increases with neutron fluence ({Phi}{sub n}) at low {phi}{sub n} (<10{sup 13} n/cm{sup 2}) and saturates at a value between 300 and 400 k{Omega}-cm at {phi}{sub n} {approximately}10{sup 13} n/cm{sup 2}. Meanwhile, the effective doping concentration N{sub eff} in the space charge region (SCR) obtained from the C-V measurements of fully depleted p{sup +}/n silicon junction detectors has been found to increase nearly linearly with {phi}{sub n} at high fluences ({phi}{sub n} > 10{sup 13} n/cm{sup 2}). The experimental results are explained by the deep levels crossing the Fermi level in the SCR and near perfect compensation in the ENB by all deep levels, resulting in N{sub eff} (SCR) {ne} n or p (free carrier concentrations in the ENB).

  8. Why silicon is and will remain the dominant photovoltaic material

    NASA Astrophysics Data System (ADS)

    Singh, Rajendra

    2009-07-01

    Rising demands of energy in emerging economies, coupled with the green house gas emissions related problems around the globe have provided a unique opportunity of exploiting the advantages offered by photovoltaic (PV) systems for green energy electricity generation. Similar to cell phones, power generated by PV systems can reach over two billion people worldwide who have no access to clean energy. Only silicon based PV devices meet the low-cost manufacturing criterion of clean energy conversion (abundance of raw material and no environmental health and safety issues). The use of larger size glass substrates and manufacturing techniques similar to the ones used by the liquid crystal display industry and the large scale manufacturing of amorphous silicon thin films based modules (~ GW per year manufacturing at a single location) can lead to installed PV system cost of $3/Wp. This will open a huge market for grid connected PV systems and related markets. With further research and development, this approach can provide $2/Wp installed PV system costs in the next few years. At this cost level, PV electricity generation is competitive with any other technology, and PV power generation can be a dominant electricity generation technology in the 21st century.

  9. Silicon materials task of the Low Cost Solar Array Project: Effect of impurities and processing on silicon solar cells

    NASA Technical Reports Server (NTRS)

    Hopkins, R. H.; Davis, J. R.; Rohatgi, A.; Hanes, M. H.; Rai-Choudhury, P.; Mollenkopf, H. C.

    1982-01-01

    The effects of impurities and processing on the characteristics of silicon and terrestrial silicon solar cells were defined in order to develop cost benefit relationships for the use of cheaper, less pure solar grades of silicon. The amount of concentrations of commonly encountered impurities that can be tolerated in typical p or n base solar cells was established, then a preliminary analytical model from which the cell performance could be projected depending on the kinds and amounts of contaminants in the silicon base material was developed. The impurity data base was expanded to include construction materials, and the impurity performace model was refined to account for additional effects such as base resistivity, grain boundary interactions, thermal processing, synergic behavior, and nonuniform impurity distributions. A preliminary assessment of long term (aging) behavior of impurities was also undertaken.

  10. Integration of active materials with silicon micromachining: applications to optical MEMS

    NASA Astrophysics Data System (ADS)

    Gouy, Jean-Philippe; Arakawa, Yasuhiko; Fujita, Hiroyuki

    2001-11-01

    Most of the MOEMS including optical switches and micro optical benches are developed on silicon. As for the MEMS, the main reason is that silicon has consistently been the material of choice for the microelectronics industry, due to a mature processing technology which offers the possibility to integrate MEMS devices with Integrated Circuits in a low cost batch fabrication process. However, since the beginning of Optoelectronic, silicon has been suffering from its poor efficiency to emit light because of its indirect band gap. Optical active devices can be integrated on silicon by combining specific active materials in order to keep the main advantage of silicon micromachining for MOEMS applications. This paper illustrates this purpose through one project developed in the frame of the LIMMS, joint laboratory between France and Japan. This project deals with optical active devices for which silicon micromachining technology has been employed to fabricate an organic semiconductors based light emitted diode on silicon substrate.

  11. Piezoresistance and hole transport in beryllium-doped silicon.

    NASA Technical Reports Server (NTRS)

    Littlejohn, M. A.; Robertson, J. B.

    1972-01-01

    The resistivity and piezoresistance of p-type silicon doped with beryllium have been studied as a function of temperature, crystal orientation, and beryllium doping concentration. It is shown that the temperature coefficient of resistance can be varied and reduced to zero near room temperature by varying the beryllium doping level. Similarly, the magnitude of the piezoresistance gauge factor for beryllium-doped silicon is slightly larger than for silicon doped with a shallow acceptor impurity such as boron, while the temperature coefficient of piezoresistance is about the same for material containing these two dopants. These results are discussed in terms of a model for the piezoresistance of compensated p-type silicon.

  12. Silicon materials outlook study for 1980-1985 calendar years

    NASA Technical Reports Server (NTRS)

    Costogue, E.; Ferber, R.; Hasbach, W.; Pellin, R.; Yaws, C.

    1979-01-01

    The polycrystalline silicon industry was studied in relation to future market needs. Analysis of the data obtained indicates that there is a high probability of polycrystalline silicon shortage by the end of 1982 and a strong seller's market after 1981 which will foster price competition for available silicon.

  13. [Adhesion of dental silicone rubber material to thermoplastic material for mouthguards].

    PubMed

    Yokota, Kayoko

    2010-03-01

    A preliminary study revealed that an autopolymerization addition silicone resilient denture relining material (SI) had excellent shock absorption properties similar to those of thermoplastic materials commonly used for mouthguards (ethylene-vinyl acetate: EVA). The aim of the present study was to examine the bonding strength of SI and EVA using a newly-developed adhesive prototype. Delamination tests and tensile strength tests were performed to compare the bonding strengths of SI on EVA prepared under the following four conditions: 1) Control condition (no preparation; C), 2) Sandblasting (S), 3) Bonding with the adhesive prototype (M), and 4) Combination of sandblasting preparation and bonding with the adhesive prototype (SM). The mean bonding strength (S. D.) of the delamination tests under the C, S, M and SM conditions were 0.167 (0.003) N/mm, 0.273 (0.034) N/mm, 0.242 (0.027) N/mm and 0.506 (0.113) N/mm, respectively. The mean bonding strength (S. D.) of the tensile strength tests under the C, S, M and SM conditions were 0.006 (0.011) MPa, 0.081 (0.105) MPa, 0.231 (0.069) MPa and 0.590 (0.041) MPa, respectively. Two-way analysis of variances and Tukey's HSD test detected that the combination of sandblasting preparation and bonding with the adhesive prototype significantly improved the bonding strength between SI and EVA. The results indicate that the self-curing addition silicone resilient denture relining material may adhere to the thermoplastic material prepared by combined application of sandblasting and the adhesive prototype, suggesting the potential of the dental silicone rubber material as a material for repairing mouthguards in clinical practice. PMID:20415249

  14. Silicon quantum dot superlattice solar cell structure including silicon nanocrystals in a photogeneration layer

    PubMed Central

    2014-01-01

    The solar cell structure of n-type poly-silicon/5-nm-diameter silicon nanocrystals embedded in an amorphous silicon oxycarbide matrix (30 layers)/p-type hydrogenated amorphous silicon/Al electrode was fabricated on a quartz substrate. An open-circuit voltage and a fill factor of 518 mV and 0.51 in the solar cell were obtained, respectively. The absorption edge of the solar cell was 1.49 eV, which corresponds to the optical bandgap of the silicon nanocrystal materials, suggesting that it is possible to fabricate the solar cells with silicon nanocrystal materials, whose bandgaps are wider than that of crystalline silicon. PACS 85.35.Be; 84.60.Jt; 78.67.Bf PMID:24936160

  15. Emissivity measurements and modeling of silicon related materials and structures

    NASA Astrophysics Data System (ADS)

    Abedrabbo, Sufian M.

    The objective of this dissertation is to investigate the major issues concerning applications of pyrometry for applications in rapid thermal processing (RTP) of silicon related materials. The research highlights of this work are: (I) Establishment of spectral emissometry as a novel, reliable and reproducible technique for: (1) Determination of wavelength and temperature dependent reflectivity, transmissivity, emissivity and temperature, simultaneously, of silicon related materials and structures. The emissometer operates in the wavelength range of 1-20μm and temperature range of 300-1200K. (2) The analysis of the influence of morphological effects on the radiative properties by measurement of (a) front-smooth incidence versus backside-rough incidence of single-side polished silicon wafers and (b) single versus double-side polished wafers. This is the first time in the literature that such a study is devoted to detect differences in the optical properties of the same sample. Attempts have been made to verify the Vandenabeele-Maex one-parameter model against the experimentally obtained optical properties for rough surfaces. The model has been proven to be inaccurate and inadequate for simulating the measured properties. (II) Establishment of methodologies and schemes for deconvolution of the measured optical properties to yield the fundamental constants such as absorption coefficient /alpha. Effects of wavelength, temperature, the total available free carriers both by doping and thermal generation and doping types have been considered in the deconvolution process. Comparisons have been sought with the available knowledge of α in the literature by the extensive use of the Multi-Rad model. This is a state of the art model that has been developed by MIT/SEMATECH. (III) The first detailed investigation of the radiative properties of SIMOX has been performed. (IV) The first detailed experimental measurements of the radiative properties of Si3N4 have been performed. The

  16. Compatibility Studies of Various Refractory Materials in Contact with Molten Silicon

    NASA Technical Reports Server (NTRS)

    Odonnell, T.; Leipold, M. H.; Hagan, M.

    1978-01-01

    The production of low cost, efficient solar cells for terrestrial electric power generation involves the manipulation of molten silicon with a present need for noncontaminating, high temperature refractories to be used as containment vessels, ribbon-production dies, and dip-coated substrates. Studies were conducted on the wetting behavior and chemical/physical interactions between molten silicon and various refractory materials.

  17. Silicon materials task of the low cost solar array project, part 2

    NASA Technical Reports Server (NTRS)

    Hopkins, R. H.; Davis, J. R.; Rai-Choudhury, P.; Blais, P. D.; Mccormick, J. R.

    1976-01-01

    Purity requirements for solar cell grade silicon material was developed and defined by evaluating the effects of specific impurities and impurity levels on the performance of silicon solar cells. Also, data was generated forming the basis for cost-tradeoff analyses of silicon solar cell material. Growth, evaluation, solar cell fabrication and testing was completed for the baseline boron-doped Czochralski material. Measurements indicate Cn and Mn seriously degrade cell performance, while neither Ni nor Cu produce any serious reduction in cell efficiency.

  18. Bioengineered Silicon Diatoms: Adding Photonic Features to a Nanostructured Semiconductive Material for Biomolecular Sensing

    NASA Astrophysics Data System (ADS)

    Rea, Ilaria; Terracciano, Monica; Chandrasekaran, Soundarrajan; Voelcker, Nicolas H.; Dardano, Principia; Martucci, Nicola M.; Lamberti, Annalisa; De Stefano, Luca

    2016-09-01

    Native diatoms made of amorphous silica are first converted into silicon structures via magnesiothermic process, preserving the original shape: electron force microscopy analysis performed on silicon-converted diatoms demonstrates their semiconductor behavior. Wet surface chemical treatments are then performed in order to enhance the photoluminescence emission from the resulting silicon diatoms and, at the same time, to allow the immobilization of biological probes, namely proteins and antibodies, via silanization. We demonstrate that light emission from semiconductive silicon diatoms can be used for antibody-antigen recognition, endorsing this material as optoelectronic transducer.

  19. Bioengineered Silicon Diatoms: Adding Photonic Features to a Nanostructured Semiconductive Material for Biomolecular Sensing.

    PubMed

    Rea, Ilaria; Terracciano, Monica; Chandrasekaran, Soundarrajan; Voelcker, Nicolas H; Dardano, Principia; Martucci, Nicola M; Lamberti, Annalisa; De Stefano, Luca

    2016-12-01

    Native diatoms made of amorphous silica are first converted into silicon structures via magnesiothermic process, preserving the original shape: electron force microscopy analysis performed on silicon-converted diatoms demonstrates their semiconductor behavior. Wet surface chemical treatments are then performed in order to enhance the photoluminescence emission from the resulting silicon diatoms and, at the same time, to allow the immobilization of biological probes, namely proteins and antibodies, via silanization. We demonstrate that light emission from semiconductive silicon diatoms can be used for antibody-antigen recognition, endorsing this material as optoelectronic transducer. PMID:27637897

  20. Reduced thermal conductivity due to scattering centers in p-type SiGe alloys

    NASA Technical Reports Server (NTRS)

    Beaty, John S.; Rolfe, Jonathon L.; Vandersande, Jan; Fleurial, Jean-Pierre

    1992-01-01

    Spark erosion was used to produce ultra-fine particles of SiGe thermoelectric material and boron nitride, an inert phonon-scattering material. A homogeneous powder was made by mixing the two powders. The mixture was hot pressed to produce a thermoelectric material with uniformity dispersed, ultra-fine, inert, phonon-scattering centers. It is shown that, in samples with inert boron nitride or silicon nitride, thermal conductivity of a SiGe alloy can be reduced by about 25 percent while maintaining the electrical properties of the samples. Annealing of all the samples at 1525 K caused grain growth to over a micron, eliminating the detrimental effect attributable to small grains. Only in the sample with boron nitride the thermal conductivity did remain well below that for standard p-type SiGe (about 25 percent), while the electrical resistivity and Seebeck coefficient were very close to the values for standard p-type 80/20 SiGe.

  1. Silicon material task. Part 3: Low-cost silicon solar array project

    NASA Technical Reports Server (NTRS)

    Roques, R. A.; Coldwell, D. M.

    1977-01-01

    The feasibility of a process for carbon reduction of low impurity silica in a plasma heat source was investigated to produce low-cost solar-grade silicon. Theoretical aspects of the reaction chemistry were studied with the aid of a computer program using iterative free energy minimization. These calculations indicate a threshold temperature exists at 2400 K below which no silicon is formed. The computer simulation technique of molecular dynamics was used to study the quenching of product species.

  2. Reaction-Based SiC Materials for Joining Silicon Carbide Composites for Fusion Energy

    SciTech Connect

    Lewinsohn, Charles A.; Jones, Russell H.; Singh, M.; Serizawa, H.; Katoh, Y.; Kohyama, A.

    2000-09-01

    The fabrication of large or complex silicon carbide-fiber-reinforced silicon carbide (SiC/SiC) components for fusion energy systems requires a method to assemble smaller components that are limited in size by manufacturing constraints. Previous analysis indicates that silicon carbide should be considered as candidate joint materials. Two methods to obtain SiC joints rely on a reaction between silicon and carbon to produce silicon carbide. This report summarizes preliminary mechanical properties of joints formed by these two methods. The methods appear to provide similar mechanical properties. Both the test methods and materials are preliminary in design and require further optimization. In an effort to determine how the mechanical test data is influenced by the test methodology and specimen size, plans for detailed finite element modeling (FEM) are presented.

  3. A study of the applicability of gallium arsenide and silicon carbide as aerospace sensor materials

    NASA Technical Reports Server (NTRS)

    Hurley, John S.

    1990-01-01

    Most of the piezoresistive sensors, to date, are made of silicon and germanium. Unfortunately, such materials are severly restricted in high temperature environments. By comparing the effects of temperature on the impurity concentrations and piezoresistive coefficients of silicon, gallium arsenide, and silicon carbide, it is being determined if gallium arsenide and silicon carbide are better suited materials for piezoresistive sensors in high temperature environments. The results show that the melting point for gallium arsenide prevents it from solely being used in high temperature situations, however, when used in the alloy Al(x)Ga(1-x)As, not only the advantage of the wider energy band gas is obtained, but also the higher desire melting temperature. Silicon carbide, with its wide energy band gap and higher melting temperature suggests promise as a high temperature piezoresistive sensor.

  4. Ohmic contact to p-type indium phosphide

    NASA Technical Reports Server (NTRS)

    Hawrylo, F. Z.

    1980-01-01

    Low-Series-resistance ohmic contact to p-type InP semiconductor material is achieved in technique utilizing Au-Ge-Zn eutectic alloy. Alloy sets and adheres well to semiconductor surface with higher acceptor concentration at metal semiconductor interface. Technique has provided satisfactory for pn junction LED's and lasers.

  5. Effect of Heat Treatment on Silicon Carbide Based Joining Materials for Fusion Energy

    SciTech Connect

    Lewinsohn, Charles A.; Jones, Russell H.; Nozawa, T.; Kotani, M.; Kishimoto, H.; Katoh, Y.; Kohyama, A.

    2001-10-01

    Two general approaches to obtaining silicon carbide-based joint materials were used. The first method relies on reactions between silicon and carbon to form silicon carbide, or to bond silicon carbide powders together. The second method consists of pyrolysing a polycarbosilane polymer to yield an amorphous, covalently bonded material. In order to assess the long-term durability of the joint materials, various heat treatments were performed and the effects on the mechanical properties of the joints were measured. Although the joints derived from the polycarbosilane polymer were not the strongest, the value of strength measured was not affected by heat treatment. On the other hand, the value of the strength of the reaction-based joints was affected by heat treatment, indicating the presence of residual stresses or unreacted material subsequent to processing. Further investigation of reaction-based joining should consist of detailed microscopic studies; however, continued study of joints derived from polymers is also warranted.

  6. Thermally conductive metal wool-silicone rubber material can be used as shock and vibration damper

    NASA Technical Reports Server (NTRS)

    Hough, W. W.

    1964-01-01

    Bronze wool pads, impregnated with silicon rubber, meet the requirement for a thermally conductive, shock and vibration absorbing material. They serve as spacers in equipment mounting and are resistant to high temperatures.

  7. Slicing of Silicon into Sheet Material. Silicon Sheet Growth Development for the Large Area Silicon Sheet Task of the Low Cost Solar Array Project

    NASA Technical Reports Server (NTRS)

    Fleming, J. R.; Holden, S. C.; Wolfson, R. G.

    1979-01-01

    The use of multiblade slurry sawing to produce silicon wafers from ingots was investigated. The commercially available state of the art process was improved by 20% in terms of area of silicon wafers produced from an ingot. The process was improved 34% on an experimental basis. Economic analyses presented show that further improvements are necessary to approach the desired wafer costs, mostly reduction in expendable materials costs. Tests which indicate that such reduction is possible are included, although demonstration of such reduction was not completed. A new, large capacity saw was designed and tested. Performance comparable with current equipment (in terms of number of wafers/cm) was demonstrated.

  8. Material and Energy Flows Associated with Select Metals in GREET 2. Molybdenum, Platinum, Zinc, Nickel, Silicon

    SciTech Connect

    Benavides, Pahola T.; Dai, Qiang; Sullivan, John L.; Kelly, Jarod C.; Dunn, Jennifer B.

    2015-09-01

    In this work, we analyzed the material and energy consumption from mining to production of molybdenum, platinum, zinc, and nickel. We also analyzed the production of solar- and semiconductor-grade silicon. We described new additions to and expansions of the data in GREET 2. In some cases, we used operating permits and sustainability reports to estimate the material and energy flows for molybdenum, platinum, and nickel, while for zinc and silicon we relied on information provided in the literature.

  9. Silicon materials task of the low cost solar array project, phase 2

    NASA Technical Reports Server (NTRS)

    Hopkins, R. H.; Davis, J. R., Jr.; Blais, P. D.; Rohatgi, A.; Rai-Choudhury, P.; Hanes, M. H.; Mccormick, J. R.

    1977-01-01

    The object of phase 2 of this program is to investigate and define the effects of various processes, contaminants and process-contaminant interactions in the performance of terrestrial solar cells. The major effort this quarter was in the areas of crystal growth and thermal processing, comparison of impurity effects in low and high resistivity silicon, modeling the behavior of p-type ingots containing Mo, and C and, quantitative analysis of bulk lifetime and junction degradation effects in contaminated solar cells. The performance of solar cells fabricated on silicon web crystals grown from melts containing about 10 to the 18th power/cu cm of Cr, Mn, Fe, Ni, Ti, and V, respectively were measured. Deep level spectroscopy of metal-contaminated ingots was employed to determine the level and density of recombination centers due to Ti, V, Ni, and Cr.

  10. Materials characterization and fracture mechanics of a space grade dielectric silicone insulation

    NASA Technical Reports Server (NTRS)

    Abdel-Latif, A. I.; Tweedie, A. T.

    1982-01-01

    The present investigation is concerned with the DC 93-500 high voltage silicone insulation material employed to pot the gun and the collector end of a traveling wave tube (TWT) used on the Landsat D Satellite. The fracture mechanics behavior of the silicone resin was evaluated by measuring the slow crack velocity as a function of the opening mode of the stress intensity factor at +25 and -10 C, taking into account various uniaxial discrete strain values. It was found that the silicone resins slow crack growth is faster than that for a high voltage insulation polyurethane material at the same stress intensity factor value and room temperature.

  11. Prize for Industrial Applications of Physics: Materials science, microelectronics scaling, and beyond the silicon transistor

    NASA Astrophysics Data System (ADS)

    Guha, Supratik

    2015-03-01

    Conventional density and performance scaling of the silicon microprocessor will reach an end within about a decade. In anticipation of this, there has been extensive interest in examining materials and devices that will replace silicon transistors. There is also the more far reaching interest in going beyond conventional computing and exploring non-Boolean forms of logic, and the devices and materials that will go with it. I will describe some of the research at IBM in these areas, including our work in developing carbon nanotube transistors as a drop in replacement for the silicon MOSFET.

  12. Improved thermal isolation of silicon suspended platforms for an all-silicon thermoelectric microgenerator based on large scale integration of Si nanowires as thermoelectric material

    NASA Astrophysics Data System (ADS)

    Fonseca, L.; Donmez, I.; Salleras, M.; Calaza, C.; Gadea, G.; Santos, J. D.; Morata, A.; Tarancon, A.

    2015-12-01

    Special suspended micro-platforms have been designed as a part of silicon compatible planar thermoelectric microgenerators. Bottom-up grown silicon nanowires are going to bridge in the future such platforms to the surrounding silicon bulk rim. They will act as thermoelectric material thus configuring an all-silicon thermoelectric device. In the new platform design other additional bridging elements (usually auxiliary support silicon beams) are substituted by low conductance thin film dielectric membranes in order to maximize the temperature difference developed between both areas. These membranes follow a sieve-like design that allows fabricating them with a short additional wet anisotropic etch step.

  13. Use of silicon oxynitride as a sacrificial material for microelectromechanical devices

    DOEpatents

    Habermehl, Scott D.; Sniegowski, Jeffry J.

    2001-01-01

    The use of silicon oxynitride (SiO.sub.x N.sub.y) as a sacrificial material for forming a microelectromechanical (MEM) device is disclosed. Whereas conventional sacrificial materials such as silicon dioxide and silicate glasses are compressively strained, the composition of silicon oxynitride can be selected to be either tensile-strained or substantially-stress-free. Thus, silicon oxynitride can be used in combination with conventional sacrificial materials to limit an accumulation of compressive stress in a MEM device; or alternately the MEM device can be formed entirely with silicon oxynitride. Advantages to be gained from the use of silicon oxynitride as a sacrificial material for a MEM device include the formation of polysilicon members that are substantially free from residual stress, thereby improving the reliability of the MEM device; an ability to form the MEM device with a higher degree of complexity and more layers of structural polysilicon than would be possible using conventional compressively-strained sacrificial materials; and improved manufacturability resulting from the elimination of wafer distortion that can arise from an excess of accumulated stress in conventional sacrificial materials. The present invention is useful for forming many different types of MEM devices including accelerometers, sensors, motors, switches, coded locks, and flow-control devices, with or without integrated electronic circuitry.

  14. Europium Silicide – a Prospective Material for Contacts with Silicon

    PubMed Central

    Averyanov, Dmitry V.; Tokmachev, Andrey M.; Karateeva, Christina G.; Karateev, Igor A.; Lobanovich, Eduard F.; Prutskov, Grigory V.; Parfenov, Oleg E.; Taldenkov, Alexander N.; Vasiliev, Alexander L.; Storchak, Vyacheslav G.

    2016-01-01

    Metal-silicon junctions are crucial to the operation of semiconductor devices: aggressive scaling demands low-resistive metallic terminals to replace high-doped silicon in transistors. It suggests an efficient charge injection through a low Schottky barrier between a metal and Si. Tremendous efforts invested into engineering metal-silicon junctions reveal the major role of chemical bonding at the interface: premier contacts entail epitaxial integration of metal silicides with Si. Here we present epitaxially grown EuSi2/Si junction characterized by RHEED, XRD, transmission electron microscopy, magnetization and transport measurements. Structural perfection leads to superb conductivity and a record-low Schottky barrier with n-Si while an antiferromagnetic phase invites spin-related applications. This development opens brand-new opportunities in electronics. PMID:27211700

  15. Europium Silicide – a Prospective Material for Contacts with Silicon

    NASA Astrophysics Data System (ADS)

    Averyanov, Dmitry V.; Tokmachev, Andrey M.; Karateeva, Christina G.; Karateev, Igor A.; Lobanovich, Eduard F.; Prutskov, Grigory V.; Parfenov, Oleg E.; Taldenkov, Alexander N.; Vasiliev, Alexander L.; Storchak, Vyacheslav G.

    2016-05-01

    Metal-silicon junctions are crucial to the operation of semiconductor devices: aggressive scaling demands low-resistive metallic terminals to replace high-doped silicon in transistors. It suggests an efficient charge injection through a low Schottky barrier between a metal and Si. Tremendous efforts invested into engineering metal-silicon junctions reveal the major role of chemical bonding at the interface: premier contacts entail epitaxial integration of metal silicides with Si. Here we present epitaxially grown EuSi2/Si junction characterized by RHEED, XRD, transmission electron microscopy, magnetization and transport measurements. Structural perfection leads to superb conductivity and a record-low Schottky barrier with n-Si while an antiferromagnetic phase invites spin-related applications. This development opens brand-new opportunities in electronics.

  16. Europium Silicide - a Prospective Material for Contacts with Silicon.

    PubMed

    Averyanov, Dmitry V; Tokmachev, Andrey M; Karateeva, Christina G; Karateev, Igor A; Lobanovich, Eduard F; Prutskov, Grigory V; Parfenov, Oleg E; Taldenkov, Alexander N; Vasiliev, Alexander L; Storchak, Vyacheslav G

    2016-01-01

    Metal-silicon junctions are crucial to the operation of semiconductor devices: aggressive scaling demands low-resistive metallic terminals to replace high-doped silicon in transistors. It suggests an efficient charge injection through a low Schottky barrier between a metal and Si. Tremendous efforts invested into engineering metal-silicon junctions reveal the major role of chemical bonding at the interface: premier contacts entail epitaxial integration of metal silicides with Si. Here we present epitaxially grown EuSi2/Si junction characterized by RHEED, XRD, transmission electron microscopy, magnetization and transport measurements. Structural perfection leads to superb conductivity and a record-low Schottky barrier with n-Si while an antiferromagnetic phase invites spin-related applications. This development opens brand-new opportunities in electronics. PMID:27211700

  17. LSA silicon material task closed-cycle process development

    NASA Technical Reports Server (NTRS)

    Roques, R. A.; Wakefield, G. F.; Blocher, J. M., Jr.; Browning, M. F.; Wilson, W.

    1979-01-01

    The initial effort on feasibility of the closed cycle process was begun with the design of the two major items of untested equipment, the silicon tetrachloride by product converter and the rotary drum reactor for deposition of silicon from trichlorosilane. The design criteria of the initial laboratory equipment included consideration of the reaction chemistry, thermodynamics, and other technical factors. Design and construction of the laboratory equipment was completed. Preliminary silicon tetrachloride conversion experiments confirmed the expected high yield of trichlorosilane, up to 98 percent of theoretical conversion. A preliminary solar-grade polysilicon cost estimate, including capital costs considered extremely conservative, of $6.91/kg supports the potential of this approach to achieve the cost goal. The closed cycle process appears to have a very likely potential to achieve LSA goals.

  18. Low temperature coefficient of resistance and high gage factor in beryllium-doped silicon

    NASA Technical Reports Server (NTRS)

    Robertson, J. B.; Littlejohn, M. A.

    1974-01-01

    The gage factor and resistivity of p-type silicon doped with beryllium was studied as a function of temperature, crystal orientation, and beryllium doping concentration. It was shown that the temperature coefficient of resistance can be varied and reduced to zero near room temperature by varying the beryllium doping level. Similarly, the magnitude of the piezoresistance gage factor for beryllium-doped silicon is slightly larger than for silicon doped with a shallow acceptor impurity such as boron, whereas the temperature coefficient of piezoresistance is about the same for material containing these two dopants. These results are discussed in terms of a model for the piezoresistance of compensated p-type silicon.

  19. p-type metal-base transistor

    NASA Astrophysics Data System (ADS)

    Delatorre, R. G.; Munford, M. L.; Zandonay, R.; Zoldan, V. C.; Pasa, A. A.; Schwarzacher, W.; Meruvia, M. S.; Hümmelgen, I. A.

    2006-06-01

    In this work we present data from a novel p-type metal-base transistor with common-base gain α ˜1, fabricated at ambient temperature and pressure by electrodepositing sequentially on a p-type Si collector, a Co base and a Cu2O emitter. The high gain and the dependence of potential between emitter and base (VEB) on the potential between collector and base (VCB) when the emitter current (IE) is held constant both suggest that the device functions as a natural permeable base transistor for very thin metal bases.

  20. Materials and fabrication sequences for water soluble silicon integrated circuits at the 90 nm node

    NASA Astrophysics Data System (ADS)

    Yin, Lan; Bozler, Carl; Harburg, Daniel V.; Omenetto, Fiorenzo; Rogers, John A.

    2015-01-01

    Tungsten interconnects in silicon integrated circuits built at the 90 nm node with releasable configurations on silicon on insulator wafers serve as the basis for advanced forms of water-soluble electronics. These physically transient systems have potential uses in applications that range from temporary biomedical implants to zero-waste environmental sensors. Systematic experimental studies and modeling efforts reveal essential aspects of electrical performance in field effect transistors and complementary ring oscillators with as many as 499 stages. Accelerated tests reveal timescales for dissolution of the various constituent materials, including tungsten, silicon, and silicon dioxide. The results demonstrate that silicon complementary metal-oxide-semiconductor circuits formed with tungsten interconnects in foundry-compatible fabrication processes can serve as a path to high performance, mass-produced transient electronic systems.

  1. Microstructural Characterization of Reaction-Formed Silicon Carbide Ceramics. Materials Characterization

    NASA Technical Reports Server (NTRS)

    Singh, M.; Leonhardt, T. A.

    1995-01-01

    Microstructural characterization of two reaction-formed silicon carbide ceramics has been carried out by interference layering, plasma etching, and microscopy. These specimens contained free silicon and niobium disilicide as minor phases with silicon carbide as the major phase. In conventionally prepared samples, the niobium disilicide cannot be distinguished from silicon in optical micrographs. After interference layering, all phases are clearly distinguishable. Back scattered electron (BSE) imaging and energy dispersive spectrometry (EDS) confirmed the results obtained by interference layering. Plasma etching with CF4 plus 4% O2 selectively attacks silicon in these specimens. It is demonstrated that interference layering and plasma etching are very useful techniques in the phase identification and microstructural characterization of multiphase ceramic materials.

  2. Isotropic behavior of an anisotropic material: single crystal silicon

    NASA Astrophysics Data System (ADS)

    McCarter, Douglas R.; Paquin, Roger A.

    2013-09-01

    Zero defect single crystal silicon (Single-Crystal Si), with its diamond cubic crystal structure, is completely isotropic in most properties important for advanced aerospace systems. This paper will identify behavior of the three most dominant planes of the Single-Crystal Si cube (110), (100) and (111). For example, thermal and optical properties are completely isotropic for any given plane. The elastic and mechanical properties however are direction dependent. But we show through finite element analysis that in spite of this, near-isotropic behavior can be achieved with component designs that utilize the optimum elastic modulus in directions with the highest loads. Using glass frit bonding to assemble these planes is the only bonding agent that doesn't degrade the performance of Single-Crystal Si. The most significant anisotropic property of Single-Crystal Si is the Young's modulus of elasticity. Literature values vary substantially around a value of 145 GPa. The truth is that while the maximum modulus is 185 GPa, the most useful <110< crystallographic direction has a high 169 GPa, still higher than that of many materials such as aluminum and invar. And since Poisson's ratio in this direction is an extremely low 0.064, distortion in the plane normal to the load is insignificant. While the minimum modulus is 130 GPa, a calculated average value is close to the optimum at approximately 160 GPa. The minimum modulus is therefore almost irrelevant. The (111) plane, referred to as the natural cleave plane survives impact that would overload the (110) and/or (100) plane due to its superior density. While mechanical properties vary from plane to plane each plane is uniform and response is predictable. Understanding the Single-Crystal Si diamond cube provides a design and manufacture path for building lightweight Single-Crystal Si systems with near-isotropic response to loads. It is clear then that near-isotropic elastic behavior is achievable in Single-Crystal Si

  3. Effect of small scattering centers on the thermoelectric properties of p-type SiGe alloys

    NASA Technical Reports Server (NTRS)

    Beaty, John S.; Rolfe, Jonathan L.; Vandersande, Jan W.

    1991-01-01

    Theory predicts that the addition of ultra-fine, inert, phonon-scattering centers to thermoelectric materials will reduce their thermal conductivity. To investigate this prediction, ultrafine particulates (20 to 120 A) of silicon nitride have been added to boron-doped, p-type, 80/20 SiGe. All of the SiGe samples produced from ultrafine powder have lower thermal conductivities than standard SiGe, but high-temperature heat treatment increases the thermal conductivity back to the value for standard SiGe. However, the SiGe samples with silicon nitride, inert, phonon-scattering centers retained the lower thermal conductivity after several heat treatments. A reduction of approximately 25 percent in thermal conductivity has been achieved in these samples. The magnitude of the reduction agrees with theoretical predictions.

  4. Purity of (28)Si-Enriched Silicon Material Used for the Determination of the Avogadro Constant.

    PubMed

    D'Agostino, Giancarlo; Di Luzio, Marco; Mana, Giovanni; Oddone, Massimo; Bennett, John W; Stopic, Attila

    2016-07-01

    At present, counting atoms in a one-kilogram sphere made of (28)Si-enriched silicon allows the determination of the Avogadro constant with the 2.0 × 10(-8) relative standard uncertainty required for the realization of the definition of the new kilogram. With the exception of carbon, oxygen, boron, nitrogen, and hydrogen, the claimed uncertainty is based on the postulation that the silicon material used to manufacture the sphere was above a particular level of purity. Two samples of the silicon were measured using instrumental neutron activation analysis to collect experimental data to test the purity assumption. The results obtained in two experiments carried out using different research reactor neutron sources are reported. The analysis confirmed that the silicon material was of sufficient purity by quantifying the ultratrace concentration of 12 elements and determining the detection limits of another 54 elements.

  5. Assessment of the advanced clay bonded silicon carbide candle filter materials. Topical report, September 1995

    SciTech Connect

    Alvin, M.A.

    1995-07-01

    Advancements have been made during the past five years to not only increase the strength of the as-manufactured clay bonded silicon carbide candle filter materials, but also to improve their high temperature creep resistance properties. This report reviews these developments, and describes the results of preliminary qualification testing which has been conducted at Westinghouse prior to utilizing the advanced clay bonded silicon carbide filters in high temperature, pressurized, coal-fired combustion and/or gasification applications.

  6. Temperature-Dependent Young's modulus, shear modulus and Poisson's ratio of p-type Ce0.9Fe3.5Co0.5Sb12 and n-type Co0.95Pd0.05Te0.05Sb3 Skutterudite Thermoelectric Materials

    SciTech Connect

    Schmidt, Robert; Case, Eldon D; Ni, Jennifer E.; Trejo, Rosa M; Lara-Curzio, Edgar

    2012-01-01

    Effective models of the mechanical behavior of thermoelectric materials under device conditions require knowledge of the temperature-dependent elastic properties.Between room temperature and 600 K, Resonant Ultrasound Spectroscopy (RUS) measurements of the Young s and shear moduli of three skutterudite thermoelectric materials, n-type Co0.95Pd0.05Te0.05Sb3(both with and without 0.1 atomic % cerium dopant) and p-type Ce0.9Fe3.5Co0.5Sb12, decreased linearly with temperature at a rate between -0.011 GPa/K and -0.013 GPa/K. In contrast the Poisson s ratio was approximately 0.22 for the three materials and was relatively insensitive to temperature.For temperatures > 600 K, the elastic moduli decreased more rapidly and resonance peaks broadened indicating the onset of viscoelastic behavior.The viscoelastic relaxation of the moduli was least for Ce-doped n-type material, for which grain boundary precipitates may inhibit grain boundary sliding which in turn has important implications concerning creep resistance. In addition, powder processing of the n- and p-type materials should be done cautiously since submicron-sized powders of both the n- and p-type powders were pyrophoric

  7. P-type Gate Electrode Formation Using B18H22 Ion Implantation

    NASA Astrophysics Data System (ADS)

    Henke, Dietmar; Jakubowski, Frank; Deichler, Josef; Venezia, Vincent C.; Ameen, M. S.; Harris, M. A.

    2006-11-01

    We have investigated the use of octadecaborane (B18H22) cluster ion implantation to form highly active p-type gate electrodes in a 90 nm CMOS process. As device dimensions scale, the influence of poly-depletion and short channel effect control on device performance continues to become more significant. Increasing gate electrode doping via high dose ion implantation is a standard method for reducing poly-depletion. Poly-silicon gate doping with the molecular ion B18H22 offers throughput advantages over monatomic B ion implantation. For instance each molecular ion introduces 18-B atoms, thereby reducing the implant dose. In addition, each B constituent of the molecular ion is implanted with 1/20th the ion energy, making it possible to achieve low energy dopant distribution while taking advantage of higher beam energy currents. In this work, B18H22 implantation conditions (energy, dose) were matched to those of the standard B+ process of record (POR) used for gate electrode doping. We show that the poly-depletion, threshold voltage, and yield of devices implanted with B18H22 are comparable to those implanted with the POR. We combine this device results with materials data to demonstrate that the high dose implants necessary to form p-type gate electrodes with minimum poly-depletion can be achieved with B18H22 ion implants without impacting the device performance.

  8. Ligand Doping on the Hybrid Thermoelectric Materials Based on Terthiophene-Capped Silicon Nanoparticles

    NASA Astrophysics Data System (ADS)

    Ashby, Shane P.; Bian, Tiezheng; Guélou, Gabin; Powell, Anthony V.; Chao, Yimin

    2016-03-01

    Over the past 2 years, silicon nanoparticles (SiNPs) functionalised with conjugated molecules have been shown to have potential as low-temperature thermoelectric materials. One key challenge with such materials relates to the introduction of charge carriers. There are two components of organic/silicon nanocomposite materials in which charge carriers can be introduced: the silicon nanoparticle or the organic ligand. Investigation into the effect of introducing charge carriers on the ligands via oxidation is another step towards understanding and optimising this kind of system. Terthiophene-capped SiNPs have been synthesised and characterised before and after doping. Using different ratios and the oxidant NOBF4 to dope the surface ligands, the electrical conductivity has been measured at ambient temperature. The ratio of oxidant to nanoparticles shows similar trends in electrical resistivity to that of conventional conductive polymers and shows significant improvements over the undoped material.

  9. Study of silicone-based materials for the packaging of optoelectronic devices

    NASA Astrophysics Data System (ADS)

    Lin, Yeong-Her

    The first part of this work is to evaluate the main materials used for the packaging of high power light-emitting diodes (LEDs), i.e., the die attach materials, the encapsulant materials, and high color rendering index(CRI) sol-gel composite materials. All of these materials had been discussed the performance, reliability, and issues in high power LED packages. High power white LEDs are created either from blue or near-ultraviolet chips encapsulated with a yellow phosphor, or from red-green-blue LED light mixing systems. The phosphor excited by blue LED chip was mostly used in experiment of this dissertation. The die attach materials contains filler particles possessing a maximum particle size less than 1.5 mum in diameter blended with epoxy polymer matrix. Such compositions enable thin bond line thickness, which decreases thermal resistance that exists between thermal interface materials and the corresponding mating surfaces. The thermal conductivity of nano silver die attach materials is relatively low, the thermal resistance from the junction to board is just 1.6 KW-1 in the bond line thickness of 5.3 mum, which is much lower than the thermal resistance using conventional die attach materials. The silicone die attach adhesive made in the lab cures through the free radical reaction of epoxy-functional organopolysiloxane and through the hydrosilylation reaction between alkenyl-functional organopolysiloxane and silicone-boned hydrogen-functional organopolysiloxane. By the combination of the free radical reaction and the hydrosilylation reaction, the low-molecular-weight silicone oil will not be out-migrated and not contaminate wire bondability to the LED chip and lead frame. Hence, the silicone die attach adhesive made in the lab can pass all reliability tests, such as operating life test JEDEC 85°C/85RH and room temperature operating life test. For LED encapsulating materials, most of commercial silicone encapsulants still suffer thermal/radiation induced

  10. [Aspects of the biological behaviour of the rubber RS 330T-RTV silicon material].

    PubMed

    Gheban, E; Forna, Norina Consuela

    2008-01-01

    The resorption and atrophy of the prosthodontic prosthetic field via the mobile restorations made of flexible acrylate, constitutes a controversial problem in the specialty literature, determining the interest of the clinicians with regard to the counterattacking or improving this process inherent to the indentation evolution. The study aims at analyzing the biological behavior of the silicon type RUBBER RS 330T-RTV, a material often used in the creation of the maxilo-facial prosthetics. The method proposed by us has the object of lining the prosthetics made of flexible acrylic type Valplast with this type of silicon. The practical aspects have been forwarded by the biocompatibility studies, applied to the silicon test-tubes, made in the dental technique laboratory, or to the hypodermic implants at the rodent laboratory animals. At the macroscopic examination it can be observed that the silicon fragment maintains it's almost parallelepiped form. The microscopic exam reveals structural mending phenomena, initially mainly the lymphohistocyte cells, and then mainly the fibrous cells. Biocompatibility aspects certifiable at the RUBBER RS 330T-RTV silicon material are fully according to the biocompatibility notions afferent to the silicon materials. Key words: PMID:20209792

  11. Progress research of non-Cz silicon material

    NASA Technical Reports Server (NTRS)

    Campbell, R. B.

    1983-01-01

    The simultaneous diffusion of liquid boron and liquid phosphorus dopants into N-type dendritic silicon web for solar cells was investigated. It is planned that the diffusion parameters required to achieve the desired P(+)NN(+) cell structure be determined and the resultant cell properties be compared to cells produced in a sequential differential process. A cost analysis of the simultaneous junction formation process is proposed.

  12. Synthesis and electrochemical characterization of Silicon clathrates as anode materials for Lithium ion batteries

    NASA Astrophysics Data System (ADS)

    Raghavan, Rahul

    Novel materials for Li-ion batteries is one of the principle thrust areas for current research in energy storage, more so than most, considering its widespread use in portable electronic gadgets and plug-in electric and hybrid cars. One of the major limiting factors in a Li-ion battery's energy density is the low specific capacities of the active materials in the electrodes. In the search for high-performance anode materials for Li-ion batteries, many alternatives to carbonaceous materials have been studied. Both cubic and amorphous silicon can reversibly alloy with lithium and have a theoretical capacity of 3500 mAh/g, making silicon a potential high density anode material. However, a large volume expansion of 300% occurs due to changes in the structure during lithium insertion, often leading to pulverization of the silicon. To this end, a class of silicon based cage compounds called clathrates are studied for electrochemical reactivity with lithium. Silicon-clathrates consist of silicon covalently bonded in cage structures comprised of face sharing Si20, Si24 and/or Si28 clusters with guest ions occupying the interstitial positions in the polyhedra. Prior to this, silicon clathrates have been studied primarily for their superconducting and thermoelectric properties. In this work, the synthesis and electrochemical characterization of two categories of silicon clathrates - Type-I silicon clathrate with aluminum framework substitution and barium guest ions (Ba8AlxSi46-x) and Type-II silicon clathrate with sodium guest ions (Nax Si136), are explored. The Type-I clathrate, Ba8AlxSi46-x consists of an open framework of aluminium and silicon, with barium (guest) atoms occupying the interstitial positions. X-ray diffraction studies have shown that a crystalline phase of clathrate is obtained from synthesis, which is powdered to a fine particle size to be used as the anode material in a Li-ion battery. Electrochemical measurements of these type of clathrates have shown

  13. ESP – Data from Restarted Life Tests of Various Silicon Materials

    SciTech Connect

    Schneider, Jim

    2010-10-06

    Current funding has allowed the restart of testing of various silicone materials placed in Life Tests or Aging Studies from past efforts. Some of these materials have been in test since 1982, with no testing for approximately 10 years, until funding allowed the restart in FY97. Charts for the various materials at different thickness, compression, and temperature combinations illustrate trends for the load-bearing properties of the materials.

  14. Well-constructed silicon-based materials as high-performance lithium-ion battery anodes

    NASA Astrophysics Data System (ADS)

    Liu, Lehao; Lyu, Jing; Li, Tiehu; Zhao, Tingkai

    2015-12-01

    Silicon has been considered as one of the most promising anode material alternates for next-generation lithium-ion batteries, because of its high theoretical capacity, environmental friendliness, high safety, low cost, etc. Nevertheless, silicon-based anode materials (especially bulk silicon) suffer from severe capacity fading resulting from their low intrinsic electrical conductivity and great volume variation during lithiation/delithiation processes. To address this challenge, a few special constructions from nanostructures to anchored, flexible, sandwich, core-shell, porous and even integrated structures, have been well designed and fabricated to effectively improve the cycling performance of silicon-based anodes. In view of the fast development of silicon-based anode materials, we summarize their recent progress in structural design principles, preparation methods, morphological characteristics and electrochemical performance by highlighting the material structure. We also point out the associated problems and challenges faced by these anodes and introduce some feasible strategies to further boost their electrochemical performance. Furthermore, we give a few suggestions relating to the developing trends to better mature their practical applications in next-generation lithium-ion batteries.

  15. Silicone impression material foreign body in the middle ear: Two case reports and literature review.

    PubMed

    Suzuki, Nobuyoshi; Okamura, Koji; Yano, Takuya; Moteki, Hideaki; Kitoh, Ryosuke; Takumi, Yutaka; Usami, Shin-ichi

    2015-10-01

    We report two cases of impression material foreign body in the middle ear. The first case had been affected with chronic otitis media. The silicone flowed into the middle ear through a tympanic membrane perforation during the process of making an ear mold. About 4 years and 8 months after, the patient had severe vertigo and deafness. We found bone erosion of the prominence of the lateral semicircular canal and diagnosed labyrinthitis caused by silicone impression material. In the second case silicone flowed into the canal wall down mastoid cavity. Both cases required surgery to remove the foreign body. The clinical courses in such cases are variable and timing of surgery is sometimes difficult. In addition to reporting these two cases, we present here a review of the literature regarding impression material foreign bodies.

  16. Implementation Challenges for Sintered Silicon Carbide Fiber Bonded Ceramic Materials for High Temperature Applications

    NASA Technical Reports Server (NTRS)

    Singh, M.

    2011-01-01

    During the last decades, a number of fiber reinforced ceramic composites have been developed and tested for various aerospace and ground based applications. However, a number of challenges still remain slowing the wide scale implementation of these materials. In addition to continuous fiber reinforced composites, other innovative materials have been developed including the fibrous monoliths and sintered fiber bonded ceramics. The sintered silicon carbide fiber bonded ceramics have been fabricated by the hot pressing and sintering of silicon carbide fibers. However, in this system reliable property database as well as various issues related to thermomechanical performance, integration, and fabrication of large and complex shape components has yet to be addressed. In this presentation, thermomechanical properties of sintered silicon carbide fiber bonded ceramics (as fabricated and joined) will be presented. In addition, critical need for manufacturing and integration technologies in successful implementation of these materials will be discussed.

  17. Study of the effects of impurities on the properties of silicon materials and performance of silicon solar cell

    NASA Technical Reports Server (NTRS)

    Sah, C. T.

    1980-01-01

    Zinc is a major residue impurity in the preparation of solar grade silicon material by the zinc vapor reduction of silicon tetrachloride. It was found that in order to get a 17 percent AMl cell efficiency, the concentration of the zinc recombination centers in the base region of silicon solar cells must be less than 4 x 10 to the 11th power Zn/cu cm in the p-base n+/p/p+ cell and 7 x 10 to the 11th power Zn/cu cm in the n-base p+/n/n+ cell for a base dopant impurity concentration of 5 x 10 to the 14th power atoms/cu cm. If the base dopant impurity concentration is increased by a factor of 10 to 5 x 10 to the 15th power atoms/cu cm, then the maximum allowable zinc concentration is increased by a factor of about two for a 17 percent AMl efficiency. The thermal equilibrium electron and hole recombination and generation rates at the double acceptor zinc cancers were obtained from previous high field measurements as well as new measurements at zero field. The rates were used in the exact d.c. circuit model to compute the projections.

  18. Energy and angular anisotropy optimisation of a p-type diode for in vivo dosimetry in photon-beam radiotherapy.

    PubMed

    Greene, Simon; Price, Robert A

    2005-01-01

    We present simulation work using the Monte Carlo code MCNPX that shows that there is a possibility of improving the silicon p-type diode as a radiation dosemeter, by altering the construction of the diode. Altering the diode die thickness can reduce the inherent angular anisotropy of the diode, with little effect on its energy response. Conversely, the contact material and geometry have a large impact on the energy response with little effect on the inherent angular anisotropy. By correct choice of contact material, the typical over-response -100 keV relative to the response at 60Co energy can be reduced from approximately 20 to 4. It is expected that further enhancements may be made with different geometries and materials.

  19. Materials and Device Analysis of Hydrogen Plasma Prepared Silicon Surfaces

    NASA Astrophysics Data System (ADS)

    Montgomery, Jeffrey Scott

    The effects of a hydrogen plasma on a single crystal silicon wafer were characterized using both surface analysis techniques and MOS transistor evaluation. Analysis of the silicon surface was focused on the effects of the H -plasma on (i) the surface structure and microroughness as revealed by atomic force microscopy, (ii) the elemental surface constituents as revealed by AES and SIMS, and (iii) the surface electronic structure as revealed by electron diffraction techniques. MOS field effect transistors were fabricated and evaluated following identical hydrogen plasma exposures prior to gate-oxide deposition. The devices were then characterized according to threshold voltage and peak mobility. The effective mobility of each device was calculated and fit to an empirical model which accounted for electron scattering in the inversion layer due to bulk ionized impurities, bulk and surface phonons, interface charges, and interface roughness. The interaction of atomic hydrogen and a silicon surface was found to be strongly dependent on the substrate temperature during processing. The rms roughness for the boron-doped silicon surfaces used in these experiments was calculated to be 2 +/- 1 A for surfaces subjected to only ex situ cleaning. Following a H-plasma treatment for 10 minutes at a substrate temperature of 200^circC, the surface roughness increased to 23 +/- 5 A. The autocorrelation function calculated for this sample exhibited long range surface structure. Samples treated at temperatures from 500 to 700^circC for 10 minutes exhibited little or no change in surface roughness or morphology. The 700^circC case resulted a slight increase in surface morphology to 4 +/- 1 A. Testing of the MOSFET devices revealed a significant reduction in device performance for H-plasma exposures in the gate region at substrate temperatures <=q 400^circC. Devices which were subjected to the H-plasma at substrate temperatures of 500-700^circC exhibited properties similar to the control

  20. Phosphorus diffusions for gettering-induced improvement of lifetime in various silicon materials

    SciTech Connect

    Gee, J.M.

    1991-01-01

    Solar-grade silicon frequently contains large quantities of defects and impurities that can significantly degrade the excess-carrier lifetime through introduction of recombination sites. The impurities frequently include metals as well as high concentrations of high carbon and/or oxygen. Defects and impurities can also degrade the electrical properties of solar cells fabricated in solar-grade silicon by causing shunt currents or excess junction current. Fabrication of acceptable solar cells from such materials requires processes that are tolerant of, or that can even improve impure and defective material. Phosphorus diffusion is a well-known technique for gettering of impurities in silicon. The effect of phosphorus diffusion on the excess-carrier lifetime in various silicon materials was investigated. The optimum phosphorus diffusion schedule and enhancement of lifetime was found to be material specific, with substantial (5-fold) increases found for some materials. Possible reasons for the variability of phosphorus gettering with different materials is discussed. 11 refs., 6 figs., 3 tabs.

  1. A new method for training of ear framework creation by silicon dental impression material.

    PubMed

    Thadani, Sandeep M; Ladani, Parit S

    2012-01-01

    This article presents the novel method of training of creating cartilage framework for total ear reconstruction in microtia. Replica of costal cartilage harvested for real surgery was simulated by silicon dental impression material. Carving of framework was done with wood carving instruments. Silicon dental impression material gives the consistency and texture almost comparable to real costal cartilage. Sequential steps similar to actual surgery were simulated to create the three-dimensional framework.By using this novel technique, novice surgeons can practice creating ear framework and improvise their results in the actual surgery.

  2. A new method for training of ear framework creation by silicon dental impression material

    PubMed Central

    Thadani, Sandeep M.; Ladani, Parit S.

    2012-01-01

    This article presents the novel method of training of creating cartilage framework for total ear reconstruction in microtia. Replica of costal cartilage harvested for real surgery was simulated by silicon dental impression material. Carving of framework was done with wood carving instruments. Silicon dental impression material gives the consistency and texture almost comparable to real costal cartilage. Sequential steps similar to actual surgery were simulated to create the three-dimensional framework. By using this novel technique, novice surgeons can practice creating ear framework and improvise their results in the actual surgery. PMID:22754170

  3. Palladium contamination in silicon

    NASA Astrophysics Data System (ADS)

    Polignano, M. L.; Mica, I.; Ceresoli, M.; Codegoni, D.; Somaini, F.; Bianchi, I.; Volonghi, D.

    2015-04-01

    In this work palladium is characterized as a silicon contaminant by recombination lifetime, DLTS, C-V and C-t measurements of palladium-implanted wafers. Palladium introduced by ion implantation is found to remain in the solid solution in silicon after rapid thermal treatments, and to be a very effective recombination center. For this reason recombination lifetime measurements are the most sensitive method to detect palladium in silicon. Two palladium-related levels were found by DLTS in p-type material. One of these levels corresponds to a level reported in the literature as the single donor level of substitutional palladium. For what concerns MOS capacitors, palladium is responsible for negative oxide charge and for degradation of the generation lifetime. In addition, palladium is confirmed to be a very fast diffuser, which segregates at the wafer surface even with low temperature treatments (250 °C). Microscopy inspections showed that palladium precipitates and surface defects were formed upon segregation.

  4. ESP - Data From Restarted Life Tests of Various Silicone Materials - 2009

    SciTech Connect

    J. W. Schneider

    2010-02-24

    Enhanced Surveillance Project (ESP) funding has allowed the restart of testing of various silicone materials placed in Life Tests or Aging Studies from past efforts. Some of these materials have been in test since 1982, with no testing for approximately 10 years, until ESP funding allowed the restart in FY97. This report will provide data on materials used on various programs and on experimental materials not used in production. Charts for the various materials at different thickness, compression, and temperature combinations illustrate trends for the load-bearing properties of the materials.

  5. ESP – Data from Restarted Life Tests of Various Silicone Materials - 2011

    SciTech Connect

    Jim Schneider

    2011-12-31

    Current funding has allowed the restart of testing of various silicone materials placed in Life Tests or Aging Studies from past efforts. Some of these materials have been in test since 1982, with no testing for approximately 10 years, until funding allowed the restart in FY97. This report will provide data on materials used in production and on experimental materials not used in production. Charts for the various materials at different thickness, compression, and temperature combinations illustrate trends for the load-bearing properties of the materials.

  6. Thermoelectric properties of gallium-doped p-type germanium

    NASA Astrophysics Data System (ADS)

    Ohishi, Yuji; Takarada, Sho; Aikebaier, Yusufu; Muta, Hiroaki; Kurosaki, Ken; Yamanaka, Shinsuke; Miyazaki, Yoshinobu; Uchida, Noriyuki; Tada, Tetsuya

    2016-05-01

    In this study, the temperature-dependent thermoelectric properties of p-type single-crystal Ge, which is a useful material for thermoelectric applications owing to its significantly high carrier mobility, were investigated. The thermoelectric properties of Ga-doped (5.7 × 1016, 3.4 × 1018, and 1.0 × 1019 cm-3) p-type single-crystal Ge were measured from room temperature to 770 K. The sample with a carrier concentration of 1.0 × 1019 cm-3 showed the highest thermoelectric figure of merit, ZT, over the entire measured temperature range. The maximum ZT value was 0.06 at 650 K. A theoretical model based on the Boltzmann transport equation with relaxation-time approximation was developed and quantitatively reproduced the experimentally observed data. The optimal impurity concentration predicted by this model was 3 × 1019 cm-3 at 300 K and increased with temperature.

  7. Use of silicon carbide sludge to form porous alkali-activated materials for insulating application

    NASA Astrophysics Data System (ADS)

    Prud'homme, E.; Joussein, E.; Rossignol, S.

    2015-07-01

    One of the objectives in the field of alkali-activated materials is the development of materials having greater thermal performances than conventional construction materials such as aerated concrete. The aim of this paper is to present the possibility to obtain controlled porosity and controlled thermal properties with geopolymer materials including a waste like silicon carbide sludge. The porosity is created by the reaction of free silicon contains in silicon carbide sludge leading to the formation of hydrogen. Two possible ways are investigated to control the porosity: modification of mixture formulation and additives introduction. The first way is the most promising and allowed the formation of materials presenting the same density but various porosities, which shows that the material is adaptable to the application. The insulation properties are logically linked to the porosity and density of materials. A lower value of thermal conductivity of 0.075 W.m-1.K-1 can be reached for a material with a low density of 0.27 g.cm-3. These characteristics are really good for a mineral-based material which always displays non-negligible resistance to manipulation.

  8. Flat-plate collector research area: Silicon material task

    NASA Technical Reports Server (NTRS)

    Lutwack, R.

    1982-01-01

    Silane decomposition in a fluidized-bed reactor (FBR) process development unit (PDU) to make semiconductor-grade Si is reviewed. The PDU was modified by installation of a new heating system to provide the required temperature profile and better control, and testing was resumed. A process for making trichlorosilane by the hydrochlorination of metallurgical-grade Si and silicon tetrachloride is reported. Fabrication and installation of the test system employing a new 2-in.-dia reactor was completed. A process that converts trichlorosilane to dichlorosilane (DCS), which is reduced by hydrogen to make Si by a chemical vapor deposition step in a Siemens-type reactor is described. Testing of the DCS PDU integraled with Si deposition reactors continued. Experiments in a 2-in.-dia reactor to define the operating window and to investigate the Si deposition kinetics were completed.

  9. Radiation Resistance Studies of Amorphous Silicon Alloy Photovoltaic Materials

    NASA Technical Reports Server (NTRS)

    Woodyard, James R.

    1994-01-01

    The radiation resistance of commercial solar cells fabricated from hydrogenated amorphous silicon alloys was investigated. A number of different device structures were irradiated with 1.0 MeV protons. The cells were insensitive to proton fluences below 1E12 sq cm. The parameters of the irradiated cells were restored with annealing at 200 C. The annealing time was dependent on proton fluence. Annealing devices for one hour restores cell parameters for fluences below lE14 sq cm require longer annealing times. A parametric fitting model was used to characterize current mechanisms observed in dark I-V measurements. The current mechanisms were explored with irradiation fluence, and voltage and light soaking times. The thermal generation current density and quality factor increased with proton fluence. Device simulation shows the degradation in cell characteristics may be explained by the reduction of the electric field in the intrinsic layer.

  10. Piezoresistive effect in p-type 3C-SiC at high temperatures characterized using Joule heating

    PubMed Central

    Phan, Hoang-Phuong; Dinh, Toan; Kozeki, Takahiro; Qamar, Afzaal; Namazu, Takahiro; Dimitrijev, Sima; Nguyen, Nam-Trung; Dao, Dzung Viet

    2016-01-01

    Cubic silicon carbide is a promising material for Micro Electro Mechanical Systems (MEMS) applications in harsh environ-ments and bioapplications thanks to its large band gap, chemical inertness, excellent corrosion tolerance and capability of growth on a Si substrate. This paper reports the piezoresistive effect of p-type single crystalline 3C-SiC characterized at high temperatures, using an in situ measurement method. The experimental results show that the highly doped p-type 3C-SiC possesses a relatively stable gauge factor of approximately 25 to 28 at temperatures varying from 300 K to 573 K. The in situ method proposed in this study also demonstrated that, the combination of the piezoresistive and thermoresistive effects can increase the gauge factor of p-type 3C-SiC to approximately 20% at 573 K. The increase in gauge factor based on the combination of these phenomena could enhance the sensitivity of SiC based MEMS mechanical sensors. PMID:27349378

  11. Piezoresistive effect in p-type 3C-SiC at high temperatures characterized using Joule heating

    NASA Astrophysics Data System (ADS)

    Phan, Hoang-Phuong; Dinh, Toan; Kozeki, Takahiro; Qamar, Afzaal; Namazu, Takahiro; Dimitrijev, Sima; Nguyen, Nam-Trung; Dao, Dzung Viet

    2016-06-01

    Cubic silicon carbide is a promising material for Micro Electro Mechanical Systems (MEMS) applications in harsh environ-ments and bioapplications thanks to its large band gap, chemical inertness, excellent corrosion tolerance and capability of growth on a Si substrate. This paper reports the piezoresistive effect of p-type single crystalline 3C-SiC characterized at high temperatures, using an in situ measurement method. The experimental results show that the highly doped p-type 3C-SiC possesses a relatively stable gauge factor of approximately 25 to 28 at temperatures varying from 300 K to 573 K. The in situ method proposed in this study also demonstrated that, the combination of the piezoresistive and thermoresistive effects can increase the gauge factor of p-type 3C-SiC to approximately 20% at 573 K. The increase in gauge factor based on the combination of these phenomena could enhance the sensitivity of SiC based MEMS mechanical sensors.

  12. Piezoresistive effect in p-type 3C-SiC at high temperatures characterized using Joule heating.

    PubMed

    Phan, Hoang-Phuong; Dinh, Toan; Kozeki, Takahiro; Qamar, Afzaal; Namazu, Takahiro; Dimitrijev, Sima; Nguyen, Nam-Trung; Dao, Dzung Viet

    2016-01-01

    Cubic silicon carbide is a promising material for Micro Electro Mechanical Systems (MEMS) applications in harsh environ-ments and bioapplications thanks to its large band gap, chemical inertness, excellent corrosion tolerance and capability of growth on a Si substrate. This paper reports the piezoresistive effect of p-type single crystalline 3C-SiC characterized at high temperatures, using an in situ measurement method. The experimental results show that the highly doped p-type 3C-SiC possesses a relatively stable gauge factor of approximately 25 to 28 at temperatures varying from 300 K to 573 K. The in situ method proposed in this study also demonstrated that, the combination of the piezoresistive and thermoresistive effects can increase the gauge factor of p-type 3C-SiC to approximately 20% at 573 K. The increase in gauge factor based on the combination of these phenomena could enhance the sensitivity of SiC based MEMS mechanical sensors. PMID:27349378

  13. Lifetime and diffusion length measurements on silicon material and solar cells

    NASA Technical Reports Server (NTRS)

    Othmer, S.; Chen, S. C.

    1978-01-01

    Experimental methods were evaluated for the determination of lifetime and diffusion length in silicon intentionally doped with potentially lifetime-degrading impurities found in metallurgical grade silicon, impurities which may be residual in low-cost silicon intended for use in terrestrial flat-plate arrays. Lifetime measurements were made using a steady-state photoconductivity method. Diffusion length determinations were made using short-circuit current measurements under penetrating illumination. Mutual consistency among all experimental methods was verified, but steady-state photoconductivity was found preferable to photoconductivity decay at short lifetimes and in the presence of traps. The effects of a number of impurities on lifetime in bulk material, and on diffusion length in cells fabricated from this material, were determined. Results are compared with those obtained using different techniques. General agreement was found in terms of the hierarchy of impurities which degrade the lifetime.

  14. Thermal/environmental barrier coating system for silicon-based materials

    NASA Technical Reports Server (NTRS)

    Spitsberg, Irene T. (Inventor); Wang, Hongyu (Inventor)

    1999-01-01

    A coating system for a substrate containing a silicon-based material, such as silicon carbide-containing ceramic matrix materials containing silicon carbide and used to form articles exposed to high temperatures, including the hostile thermal environment of a gas turbine engine. The coating system includes a layer of barium strontium aluminosilicate (BSAS) as a bond coat for a thermal-insulating top coat. As a bond coat, the BSAS layer serves to adhere the top coat to a SiC-containing substrate. The BSAS bond coat exhibits sufficient environmental resistance such that, if the top coat should spall, the BSAS bond coat continues to provide a level of environmental protection to the underlying SiC-containing substrate.

  15. Use of Monocrystalline Silicon as Tool Material for Highly Accurate Blanking of Thin Metal Foils

    SciTech Connect

    Hildering, Sven; Engel, Ulf; Merklein, Marion

    2011-05-04

    The trend towards miniaturisation of metallic mass production components combined with increased component functionality is still unbroken. Manufacturing these components by forming and blanking offers economical and ecological advantages combined with the needed accuracy. The complexity of producing tools with geometries below 50 {mu}m by conventional manufacturing methods becomes disproportional higher. Expensive serial finishing operations are required to achieve an adequate surface roughness combined with accurate geometry details. A novel approach for producing such tools is the use of advanced etching technologies for monocrystalline silicon that are well-established in the microsystems technology. High-precision vertical geometries with a width down to 5 {mu}m are possible. The present study shows a novel concept using this potential for the blanking of thin copper foils with monocrystallline silicon as a tool material. A self-contained machine-tool with compact outer dimensions was designed to avoid tensile stresses in the brittle silicon punch by an accurate, careful alignment of the punch, die and metal foil. A microscopic analysis of the monocrystalline silicon punch shows appropriate properties regarding flank angle, edge geometry and surface quality for the blanking process. Using a monocrystalline silicon punch with a width of 70 {mu}m blanking experiments on as-rolled copper foils with a thickness of 20 {mu}m demonstrate the general applicability of this material for micro production processes.

  16. InGaAlAsPN: A Materials System for Silicon Based Optoelectronics and Heterostructure Device Technologies

    NASA Technical Reports Server (NTRS)

    Broekaert, T. P. E.; Tang, S.; Wallace, R. M.; Beam, E. A., III; Duncan, W. M.; Kao, Y. -C.; Liu, H. -Y.

    1995-01-01

    A new material system is proposed for silicon based opto-electronic and heterostructure devices; the silicon lattice matched compositions of the (In,Ga,Al)-(As,P)N 3-5 compounds. In this nitride alloy material system, the bandgap is expected to be direct at the silicon lattice matched compositions with a bandgap range most likely to be in the infrared to visible. At lattice constants ranging between those of silicon carbide and silicon, a wider bandgap range is expected to be available and the high quality material obtained through lattice matching could enable applications such as monolithic color displays, high efficiency multi-junction solar cells, opto-electronic integrated circuits for fiber communications, and the transfer of existing 3-5 technology to silicon.

  17. Thermophysical properties of materials based on silicon nitride

    SciTech Connect

    Blinder, A.V.; Bolgar, A.S.; Petrovskii, V.Ya.

    1995-09-01

    The heat capacity and thermal conductivity of materials based on Si{sub 3}N{sub 4} are investigated for the first time. The temperature dependence of the thermal diffusivity of the composites studied is calculated. The influence of structural changes on the nature of the thermophysical properties of materials based on {beta}-Si{sub 3}N{sub 4}.

  18. Plasmonic silicon solar cells: impact of material quality and geometry.

    PubMed

    Pahud, Celine; Isabella, Olindo; Naqavi, Ali; Haug, Franz-Josef; Zeman, Miro; Herzig, Hans Peter; Ballif, Christophe

    2013-09-01

    We study n-i-p amorphous silicon solar cells with light-scattering nanoparticles in the back reflector. In one configuration, the particles are fully embedded in the zinc oxide buffer layer; In a second configuration, the particles are placed between the buffer layer and the flat back electrode. We use stencil lithography to produce the same periodic arrangement of the particles and we use the same solar cell structure on top, thus establishing a fair comparison between a novel plasmonic concept and its more traditional counterpart. Both approaches show strong resonances around 700 nm in the external quantum efficiency the position and intensity of which vary strongly with the nanoparticle shape. Moreover, disagreement between simulations and our experimental results suggests that the dielectric data of bulk silver do not correctly represent the reality. A better fit is obtained by introducing a porous interfacial layer between the silver and zinc oxide. Without the interfacial layer, e.g. by improved processing of the nanoparticles, our simulations show that the nanoparticles concept could outperform traditional back reflectors. PMID:24104574

  19. Preparation and properties of polyurethane/silicone materials for biomimetic gecko setae

    NASA Astrophysics Data System (ADS)

    Yu, Min; Dai, Zhendong; Yang, Shengrong

    2014-03-01

    In the biomimetic design of gecko setae, it is necessary to select materials with appropriate adhesive properties and to understand the effects of materials on normal and tangential adhesive forces. To meet the adhesion performance requirements of the biomimetic gecko robot foot, in this study, performance-improved polyurethane/silicone polymer materials were designed and synthesized, and the normal adhesion and tangential adhesion were measured using an adhesive friction comprehensive tester. The results show that normal adhesion increased with an increase in load when the normal load is small; when the normal load exceeds a critical value, the increase in normal adhesion slows and adhesion saturates. Under the condition of an adhesive state, the tangential adhesive force was larger for a smaller negative normal force, and a relatively large tangential adhesive force could be generated with a very small negative normal force. The elastic modulus of the synthetic polyurethane/silicone material varied with varying ratios of components, and it increased with increasing urethane content. Polyurethane/silicone material with about 30% polyurethane provided greater adhesion than other materials with different contents of polyurethane. The results provide a basis for the choice of biomimetic materials of the biomimetic gecko robot foot.

  20. Slicing of silicon into sheet material. Silicon sheet growth development for the large area silicon sheet task of the low cost silicon solar array project

    NASA Technical Reports Server (NTRS)

    Holden, S. C.; Fleming, J. R.

    1978-01-01

    Fabrication of a prototype large capacity multiple blade slurry saw is considered. Design of the bladehead which will tension up to 1000 blades, and cut a 45 cm long silicon ingot as large as 12 cm in diameter is given. The large blade tensioning force of 270,000 kg is applied through two bolts acting on a pair of scissor toggles, significantly reducing operator set-up time. Tests with an upside-down cutting technique resulted in 100% wafering yields and the highest wafer accuracy yet experienced with MS slicing. Variations in oil and abrasives resulted only in degraded slicing results. A technique of continuous abrasive slurry separation to remove silicon debris is described.

  1. Supercritical adsorption testing of porous silicon, activated carbon, and zeolite materials

    NASA Astrophysics Data System (ADS)

    Harvey, Brendan

    The supercritical adsorption of methane gas on porous silicon, activated carbon, and zeolite materials was studied. An apparatus that utilizes the volumetric adsorption measurement technique was designed and constructed to conduct the experiments. Activated carbon materials consisted of Norit RX3 Extra, Zorflex FM30K woven activated carbon cloth, and Zorflex FM10 knitted activated carbon cloth. Zeolite materials consisted of 3A, 4A, 5A, and 13X zeolites. Porous silicon materials consisted of stain etched and electrochemically etched porous films, and stain etched porous powder. All adsorption tests were conducted at room temperature (approximately 298 K) and pressures up to approximately 5 MPa. Overall, the Norit RX3 Extra granulated activated carbon produced the highest excess adsorption and effective storage capacities. Effective storage and delivery capacities of 109 and 90 stpmlml were obtained at a pressure of 3.5 MPa and a temperature of approximately 298 K.

  2. Joining of Silicon Carbide-Based Ceramic Materials for High Temperature Applications

    NASA Technical Reports Server (NTRS)

    Singh, Mrityunjay

    1997-01-01

    Joining of high temperature silicon carbide-based ceramics has been a critical issue for their successful application. An affordable, robust technique for joining silicon carbide-based ceramics has been developed and is capable of producing joints that can be tailored for thickness and composition. These joints maintain their mechanical strength up to 1350 C (2462 F) in air. This technique is suitable for the joining of large and complex shaped ceramic components and can be extended to the repair of these materials.

  3. Silicon nitride: A ceramic material with outstanding resistance to thermal shock and corrosion

    NASA Technical Reports Server (NTRS)

    Huebner, K. H.; Saure, F.

    1983-01-01

    The known physical, mechanical and chemical properties of reaction-sintered silicon nitride are summarized. This material deserves interest especially because of its unusually good resistance to thermal shock and corrosion at high temperatures. Two types are distinguished: reaction-sintered (porous) and hot-pressed (dense) Si3N4. Only the reaction-sintered material which is being produced today in large scale as crucibles, pipes, nozzles and tiles is considered.

  4. Formation of Mach angle profiles during wet etching of silica and silicon nitride materials

    NASA Astrophysics Data System (ADS)

    Ghulinyan, M.; Bernard, M.; Bartali, R.; Pucker, G.

    2015-12-01

    In integrated circuit technology peeling of masking photoresist films is a major drawback during the long-timed wet etching of materials. It causes an undesired film underetching, which is often accompanied by a formation of complex etch profiles. Here we report on a detailed study of wedge-shaped profile formation in a series of silicon oxide, silicon oxynitride and silicon nitride materials during wet etching in a buffered hydrofluoric acid (BHF) solution. The shape of etched profiles reflects the time-dependent adhesion properties of the photoresist to a particular material and can be perfectly circular, purely linear or a combination of both, separated by a knee feature. Starting from a formal analogy between the sonic boom propagation and the wet underetching process, we model the wedge formation mechanism analytically. This model predicts the final form of the profile as a function of time and fits the experimental data perfectly. We discuss how this knowledge can be extended to the design and the realization of optical components such as highly efficient etch-less vertical tapers for passive silicon photonics.

  5. Silicon-Containing Spin-on Underlayer Material for Step and Flash Nanoimprint Lithography

    NASA Astrophysics Data System (ADS)

    Satoshi Takei,; Tsuyoshi Ogawa,; Ryan Deschner,; Kane Jen,; Takayasu Nihira,; Makoto Hanabata,; C. Grant Willson,

    2010-07-01

    Nanoimprint lithography is a newly developed patterning method that employs a hard template for the patterning of structures at micro- and nanometer scales. This technique has many advantages such as cost reduction, high resolution, low line edge roughness (LER), and easy operation. However, resist peeling, defects, low degree of planarization, and low throughput issues present challenges that must be resolved in order to mass produce advanced nanometer-scale devices. In this study, the new approach of using a silicon-containing spin-on hard mask underlayer material with high adhesion by reacting methacrylate groups of the underlayer to the acrylate groups of resist material during ultraviolet irradiation was demonstrated to obtain the excellent patterning dimensional accuracy and increase the process latitudes. The performance of this process is evaluated by using step and flash imprint lithography. The obtained high adhesion between the underlayer and resist material was found to lead a silicon-containing underlayer material to excellent patterning dimensional accuracy and 80 nm straight profiles. We expect that the silicon-containing a spin-on hard mask material under organic resist will be one of the most promising materials in the next generation of nanoimprint lithography.

  6. Bi-Se doped with Cu, p-type semiconductor

    DOEpatents

    Bhattacharya, Raghu Nath; Phok, Sovannary; Parilla, Philip Anthony

    2013-08-20

    A Bi--Se doped with Cu, p-type semiconductor, preferably used as an absorber material in a photovoltaic device. Preferably the semiconductor has at least 20 molar percent Cu. In a preferred embodiment, the semiconductor comprises at least 28 molar percent of Cu. In one embodiment, the semiconductor comprises a molar percentage of Cu and Bi whereby the molar percentage of Cu divided by the molar percentage of Bi is greater than 1.2. In a preferred embodiment, the semiconductor is manufactured as a thin film having a thickness less than 600 nm.

  7. Vertically aligned CNT-Cu nano-composite material for stacked through-silicon-via interconnects.

    PubMed

    Sun, Shuangxi; Mu, Wei; Edwards, Michael; Mencarelli, Davide; Pierantoni, Luca; Fu, Yifeng; Jeppson, Kjell; Liu, Johan

    2016-08-19

    For future miniaturization of electronic systems using 3D chip stacking, new fine-pitch materials for through-silicon-via (TSV) applications are likely required. In this paper, we propose a novel carbon nanotube (CNT)/copper nanocomposite material consisting of high aspect ratio, vertically aligned CNT bundles coated with copper. These bundles, consisting of hundreds of tiny CNTs, were uniformly coated by copper through electroplating, and aspect ratios as high as 300:1 were obtained. The resistivity of this nanomaterial was found to be as low as ∼10(-8) Ω m, which is of the same order of magnitude as the resistivity of copper, and its temperature coefficient was found to be only half of that of pure copper. The main advantage of the composite TSV nanomaterial is that its coefficient of thermal expansion (CTE) is similar to that of silicon, a key reliability factor. A finite element model was set up to demonstrate the reliability of this composite material and thermal cycle simulations predicted very promising results. In conclusion, this composite nanomaterial appears to be a very promising material for future 3D TSV applications offering both a low resistivity and a low CTE similar to that of silicon. PMID:27383767

  8. Vertically aligned CNT-Cu nano-composite material for stacked through-silicon-via interconnects

    NASA Astrophysics Data System (ADS)

    Sun, Shuangxi; Mu, Wei; Edwards, Michael; Mencarelli, Davide; Pierantoni, Luca; Fu, Yifeng; Jeppson, Kjell; Liu, Johan

    2016-08-01

    For future miniaturization of electronic systems using 3D chip stacking, new fine-pitch materials for through-silicon-via (TSV) applications are likely required. In this paper, we propose a novel carbon nanotube (CNT)/copper nanocomposite material consisting of high aspect ratio, vertically aligned CNT bundles coated with copper. These bundles, consisting of hundreds of tiny CNTs, were uniformly coated by copper through electroplating, and aspect ratios as high as 300:1 were obtained. The resistivity of this nanomaterial was found to be as low as ˜10-8 Ω m, which is of the same order of magnitude as the resistivity of copper, and its temperature coefficient was found to be only half of that of pure copper. The main advantage of the composite TSV nanomaterial is that its coefficient of thermal expansion (CTE) is similar to that of silicon, a key reliability factor. A finite element model was set up to demonstrate the reliability of this composite material and thermal cycle simulations predicted very promising results. In conclusion, this composite nanomaterial appears to be a very promising material for future 3D TSV applications offering both a low resistivity and a low CTE similar to that of silicon.

  9. Vertically aligned CNT-Cu nano-composite material for stacked through-silicon-via interconnects

    NASA Astrophysics Data System (ADS)

    Sun, Shuangxi; Mu, Wei; Edwards, Michael; Mencarelli, Davide; Pierantoni, Luca; Fu, Yifeng; Jeppson, Kjell; Liu, Johan

    2016-08-01

    For future miniaturization of electronic systems using 3D chip stacking, new fine-pitch materials for through-silicon-via (TSV) applications are likely required. In this paper, we propose a novel carbon nanotube (CNT)/copper nanocomposite material consisting of high aspect ratio, vertically aligned CNT bundles coated with copper. These bundles, consisting of hundreds of tiny CNTs, were uniformly coated by copper through electroplating, and aspect ratios as high as 300:1 were obtained. The resistivity of this nanomaterial was found to be as low as ∼10‑8 Ω m, which is of the same order of magnitude as the resistivity of copper, and its temperature coefficient was found to be only half of that of pure copper. The main advantage of the composite TSV nanomaterial is that its coefficient of thermal expansion (CTE) is similar to that of silicon, a key reliability factor. A finite element model was set up to demonstrate the reliability of this composite material and thermal cycle simulations predicted very promising results. In conclusion, this composite nanomaterial appears to be a very promising material for future 3D TSV applications offering both a low resistivity and a low CTE similar to that of silicon.

  10. Small, short and long fatigue crack growth in an advanced silicon nitride ceramic material

    SciTech Connect

    Zhang, Y.H.; Edwards, L.

    1996-05-15

    In metallic materials, a number of workers have reported that the growth rates of small fatigue cracks cannot be correlated with the stress intensity factor range, {Delta}K. Small cracks normally exhibit faster growth rates than long cracks and often show growth rate minima. This anomalous behavior has been attributed to the failure of the linear elastic fracture mechanics parameter {Delta}K to characterize small, or short fatigue crack growth. Ceramic materials combine a lack of dislocation deformation and a very small grain size and thus the reasons for any observed anomalous small or short crack growth effect are less clear. Previous work on small or short fatigue crack growth in ceramics is limited, and work on silicon nitride which is one of the most promising structural ceramics is particularly sparse. As the majority of the fatigue lifetime of any silicon nitride component will be controlled by the propagation of a preexisting small flaw to a critical size, the presence of any short or small crack effect in this material is of engineering importance. Thus, the objective of the work presented here is to investigate the small, short and long crack growth in an advanced silicon nitride material.

  11. Vertically aligned CNT-Cu nano-composite material for stacked through-silicon-via interconnects.

    PubMed

    Sun, Shuangxi; Mu, Wei; Edwards, Michael; Mencarelli, Davide; Pierantoni, Luca; Fu, Yifeng; Jeppson, Kjell; Liu, Johan

    2016-08-19

    For future miniaturization of electronic systems using 3D chip stacking, new fine-pitch materials for through-silicon-via (TSV) applications are likely required. In this paper, we propose a novel carbon nanotube (CNT)/copper nanocomposite material consisting of high aspect ratio, vertically aligned CNT bundles coated with copper. These bundles, consisting of hundreds of tiny CNTs, were uniformly coated by copper through electroplating, and aspect ratios as high as 300:1 were obtained. The resistivity of this nanomaterial was found to be as low as ∼10(-8) Ω m, which is of the same order of magnitude as the resistivity of copper, and its temperature coefficient was found to be only half of that of pure copper. The main advantage of the composite TSV nanomaterial is that its coefficient of thermal expansion (CTE) is similar to that of silicon, a key reliability factor. A finite element model was set up to demonstrate the reliability of this composite material and thermal cycle simulations predicted very promising results. In conclusion, this composite nanomaterial appears to be a very promising material for future 3D TSV applications offering both a low resistivity and a low CTE similar to that of silicon.

  12. Bite force measurement system using pressure-sensitive sheet and silicone impression material.

    PubMed

    Ando, Katsuya; Fuwa, Yuji; Kurosawa, Masahiro; Kondo, Takamasa; Goto, Shigemi

    2009-03-01

    This study was conducted to reduce the bias in measured values caused by the thickness of materials used in occlusal examinations. To this end, a silicone impression material for bite force measurement and an experimental model of a simplified stomatognathic system were employed in this study. By means of this experimental model, results showed that the effect of bias toward the posterior arch could be reduced in the anterior-posterior distribution of bite forces and in the occlusal contact areas due to the thickness of the materials used in occlusal examinations.

  13. Design of Shallow p-type Dopants in ZnO (Presentation)

    SciTech Connect

    Wei, S.H.; Li, J.; Yan. Y.

    2008-05-01

    ZnO is a promising material for short wave-length opto-electronic devices such as UV lasers and LEDs due to its large exciton binding energy and low material cost. ZnO can be doped easily n-type, but the realization of stable p-type ZnO is rather difficult. Using first-principles band structure methods the authors address what causes the p-type doping difficulty in ZnO and how to overcome the p-type doping difficulty in ZnO.

  14. Structural silicon nitride materials containing rare earth oxides

    DOEpatents

    Andersson, Clarence A.

    1980-01-01

    A ceramic composition suitable for use as a high-temperature structural material, particularly for use in apparatus exposed to oxidizing atmospheres at temperatures of 400 to 1600.degree. C., is found within the triangular area ABCA of the Si.sub.3 N.sub.4 --SiO.sub.2 --M.sub.2 O.sub.3 ternary diagram depicted in FIG. 1. M is selected from the group of Yb, Dy, Er, Sc, and alloys having Yb, Y, Er, or Dy as one component and Sc, Al, Cr, Ti, (Mg +Zr) or (Ni+Zr) as a second component, said alloy having an effective ionic radius less than 0.89 A.

  15. Preparation and characterization of titania/silicone nanocomposite material

    NASA Astrophysics Data System (ADS)

    Shen, Y.; Wang, L.; Zhang, H.; Wu, T.; Pan, H. Y.

    2015-07-01

    The preparation and properties of high refractive index nanocomposite material were studied. The TiO2 nanoparticles were synthesized by sol-gel method using acetic acid as a chelating ligand. The nanoparticles were dispersed directly into the polymer matrix to prepare transparent high refractive index nanocomposite thin films. The refractive index of films will be enhanced with the increase of titania contents. The particles were characterized by X-ray diffraction (XRD), Transmission Electron Microscope (TEM), and Fourier Transform Infrared Spectroscopy (FTIR), respectively. The results showed that all samples with different amounts of TiO2 exhibit good optical transparency. Furthermore, the pattern of the TiO2 NPs shows a pure anatase phases. From TEM image, the TiO2 has little agglomeration. The FT-IR spectrum indicated that acetate ions and titanium ions show good chelation.

  16. Method of making silicon on insalator material using oxygen implantation

    DOEpatents

    Hite, Larry R.; Houston, Ted; Matloubian, Mishel

    1989-01-01

    The described embodiments of the present invention provide a semiconductor on insulator structure providing a semiconductor layer less susceptible to single event upset errors (SEU) due to radiation. The semiconductor layer is formed by implanting ions which form an insulating layer beneath the surface of a crystalline semiconductor substrate. The remaining crystalline semiconductor layer above the insulating layer provides nucleation sites for forming a crystalline semiconductor layer above the insulating layer. The damage caused by implantation of the ions for forming an insulating layer is left unannealed before formation of the semiconductor layer by epitaxial growth. The epitaxial layer, thus formed, provides superior characteristics for prevention of SEU errors, in that the carrier lifetime within the epitaxial layer, thus formed, is less than the carrier lifetime in epitaxial layers formed on annealed material while providing adequate semiconductor characteristics.

  17. Germanium as a Material to Enable Silicon Photonics

    NASA Astrophysics Data System (ADS)

    Ichikawa, R.; Takita, S.; Ishikawa, Y.; Wada, K.

    Germanium has been an enabler of the information age. Ge on Si nucleates Si photonics as well as high-speed CMOS electronics. Recently, Ge has played a significant role in integrating materials such as III-Vs on Si. The structure of GaAs on a thick Ge layer on Si has been studied for many years to expand its device application menu such as lasers, high-performance transistors, and tandem solar cells on Si. However, an ultra-thin Ge buffer layer (referred to as (Ge) hereafter) technology described in this chapter has created new fields for applications. One of the emerging fields is the structure and properties of AlGaAs/GaAs/(Ge)/Si/Ge, which has been impossible to create previously using the thick Ge buffer on Si technology. Here, we demonstrate an application as a new green power generation platform, i.e., high-efficiency cost-effective tandem solar cells using Si as a cell as well as the mechanical substrate. The (Ge) thickness has not been fully optimized yet, but is in the range 10-20 nm. Our design for a tandem solar cell shows that its theoretical efficiency reaches 43%. The key attributes are the crystalline quality and surface roughness of ultrathin (Ge). We have experimentally optimized the (Ge) buffer thickness to achieve both requirements and prototyped Ge solar cells on Si. The Ge solar cells have successfully reproduced their ideal external quantum efficiency. This is the proof of concept of the success of the Ge challenge as the material enabler to integrate Si and GaAs.

  18. Slicing of Silicon into Sheet Material: Silicon Sheet Growth Development for the Large Area Silicon Sheet Task of the Low Cost Silicon Solar Array Project

    NASA Technical Reports Server (NTRS)

    Fleming, J. R.

    1979-01-01

    Testing of low cost low suspension power slurry vehicles is presented. Cutting oils are unlikely to work, but a mineral oil with additives should be workable. Two different abrasives were tested. A cheaper silicon carbide from Norton gave excellent results except for excessive kerf loss: the particles were too big. An abrasive treated for lubricity showed no lubricity improvement in mineral oil vehicle. The bounce fixture was tested for the first time under constant cut rate conditions (rather than constant force). Although the cut was not completed before the blades broke, the blade lifetime of thin (100 micrometer) blades was 120 times the lifetime without the fixture. The large prototype saw completed a successful run, producing 90% cutting yield (849 wafers) at 20 wafers/cm. Although inexperience with large numbers of wafers caused cleaning breakage to reduce this yield to 74%, the yield was high enough that the concept of the large saw is proven workable.

  19. Gold nanorods-silicone hybrid material films and their optical limiting property

    NASA Astrophysics Data System (ADS)

    Li, Chunfang; Qi, Yanhai; Hao, Xiongwen; Peng, Xue; Li, Dongxiang

    2015-10-01

    As a kind of new optical limiting materials, gold nanoparticles have optical limiting property owing to their optical nonlinearities induced by surface plasmon resonance (SPR). Gold nanorods (GNRs) possess transversal SPR absorption and tunable longitudinal SPR absorption in the visible and near-infrared region, so they can be used as potential optical limiting materials against tunable laser pulses. In this letter, GNRs were prepared using seed-mediated growth method and surface-modified by silica coating to obtain good dispersion in polydimethylsiloxane prepolymers. Then the silicone rubber films doped with GNRs were prepared after vulcanization, whose optical limiting property and optical nonlinearity were investigated. The silicone rubber samples doped with more GNRs were found to exhibit better optical limiting performance.

  20. Change in color of a maxillofacial prosthetic silicone elastomer, following investment in molds of different materials

    PubMed Central

    Sethi, Tania; Kheur, Mohit; Coward, Trevor; Patel, Naimesha

    2015-01-01

    Purpose: In the authors’ experience, the color of silicone elastomer following polymerization in molds made of gypsum products is slightly different from the color that was matched in the presence of the patient, before the silicone is packed. It is hypothesized that the investing materials and separating media have an effect on the color during the polymerization process of the silicone. Materials and Methods: This study compares and evaluates the change in color of silicone elastomer packed in three commonly used investing materials - Dental stone (white color), dental stone (green color), and die stone (orange color); coated with three different separating media – Alginate-based medium, soap solution and a resin-based die hardening material. Pigmented silicone samples of dimensions 1.5 cm × 2 cm × 0.5 cm were made from the elastomer in the above-mentioned mold materials using combinations of the mentioned separating media. These served as test group samples. Control group samples were made by packing a mix of the same pigmented elastomer in stainless steel molds. The L*, a*, b* values of the test and control group samples were determined using a spectrophotometer. The change in color (Delta E) was calculated between the control and test groups. Results: The mean L, a, b values for the control group were, 31.8, 26.2, and 36.3, respectively. Average values of change in color (Delta E) for samples packed utilizing alginate-based medium, die hardener, and soap solution, respectively in white dental stone (2.70, 2.74, and 2.88), green dental stone (2.19, 2.23, 2.42), and orange die stone (3.19, 2.72, 2.80) were tabulated. Conclusion: Among the investing materials studied, die stone showed the most color change (3.19), which was statistically significant. Among the separating media, die hardener showed the least color change (2.23). The best combination of an investing material and separating media as per this investigation is a dental stone (green) and alginate

  1. 17th Workshop on Crystalline Silicon Solar Cells and Modules: Materials and Processes; Workshop Proceedings

    SciTech Connect

    Sopori, B. L.

    2007-08-01

    The National Center for Photovoltaics sponsored the 17th Workshop on Crystalline Silicon Solar Cells & Modules: Materials and Processes, held in Vail, CO, August 5-8, 2007. This meeting provided a forum for an informal exchange of technical and scientific information between international researchers in the photovoltaic and relevant non-photovoltaic fields. The theme of this year's meeting was 'Expanding Technology for a Future Powered by Si Photovoltaics.'

  2. Studies of material and process compatibility in developing compact silicon vapor chambers

    NASA Astrophysics Data System (ADS)

    Cai, Qingjun; Bhunia, Avijit; Tsai, Chialun; Kendig, Martin W.; DeNatale, Jeffrey F.

    2013-06-01

    The performance and long-term reliability of a silicon vapor chamber (SVC) developed for thermal management of high-power electronics critically depend on compatibility of the component materials. A hermetically sealed SVC presented in this paper is composed of bulk silicon, glass-frit as a bonding agent, lead/tin solder as an interface sealant and a copper charging tube. These materials, in the presence of a water/vapor environment, may chemically react and release noncondensable gas (NCG), which can weaken structural strength and degrade the heat transfer performance with time. The present work reports detailed studies on chemical compatibility of the components and potential solutions to avoid the resulting thermal performance degradation. Silicon surface oxidation and purification of operating liquid are necessary steps to reduce performance degradation in the transient period. A lead-based solder with its low reflow temperature is found to be electrochemically stable in water/vapor environment. High glazing temperature solidifies molecular bonding in glass-frit and mitigates PbO precipitation. Numerous liquid flushes guarantee removal of chemical residual after the charging tube is soldered to SVC. With these improvements on the SVC material and process compatibility, high effective thermal conductivity and steady heat transfer performance are obtained.

  3. Porous silicon as a potential electrode material in a nerve repair setting: Tissue reactions.

    PubMed

    Johansson, Fredrik; Wallman, Lars; Danielsen, Nils; Schouenborg, Jens; Kanje, Martin

    2009-07-01

    We compared porous silicon (pSi) with smooth Si as chip-implant surfaces in a nerve regeneration setting. Silicon chips can be used for recording neural activity and are potential nerve interface devices. A silicon chip with one smooth and one porous side inserted into a tube was used to bridge a 5 mm defect in rat sciatic nerve. Six or 12 weeks later, new nerve structures surrounded by a perineurium-like capsule had formed on each side of the chip. The number of regenerated nerve fibers did not differ on either side of the chip as shown by immunostaining for neurofilaments. However, the capsule that had formed in contact with the chip was significantly thinner on the porous side than on the smooth side. Cellular protrusions had formed on the pSi side and the regenerated nerve tissue was found to attach firmly to this surface, while the tissue was hardly attached to the smooth silicon surface. We conclude that a pSi surface, due to its large surface area, diminished inflammatory response and firm adhesion to the tissue, should be a good material for the development of new implantable electronic nerve devices.

  4. Composite materials and bodies including silicon carbide and titanium diboride and methods of forming same

    DOEpatents

    Lillo, Thomas M.; Chu, Henry S.; Harrison, William M.; Bailey, Derek

    2013-01-22

    Methods of forming composite materials include coating particles of titanium dioxide with a substance including boron (e.g., boron carbide) and a substance including carbon, and reacting the titanium dioxide with the substance including boron and the substance including carbon to form titanium diboride. The methods may be used to form ceramic composite bodies and materials, such as, for example, a ceramic composite body or material including silicon carbide and titanium diboride. Such bodies and materials may be used as armor bodies and armor materials. Such methods may include forming a green body and sintering the green body to a desirable final density. Green bodies formed in accordance with such methods may include particles comprising titanium dioxide and a coating at least partially covering exterior surfaces thereof, the coating comprising a substance including boron (e.g., boron carbide) and a substance including carbon.

  5. Dissolution chemistry and biocompatibility of single-crystalline silicon nanomembranes and associated materials for transient electronics.

    PubMed

    Hwang, Suk-Won; Park, Gayoung; Edwards, Chris; Corbin, Elise A; Kang, Seung-Kyun; Cheng, Huanyu; Song, Jun-Kyul; Kim, Jae-Hwan; Yu, Sooyoun; Ng, Joanne; Lee, Jung Eun; Kim, Jiyoung; Yee, Cassian; Bhaduri, Basanta; Su, Yewang; Omennetto, Fiorenzo G; Huang, Yonggang; Bashir, Rashid; Goddard, Lynford; Popescu, Gabriel; Lee, Kyung-Mi; Rogers, John A

    2014-06-24

    Single-crystalline silicon nanomembranes (Si NMs) represent a critically important class of material for high-performance forms of electronics that are capable of complete, controlled dissolution when immersed in water and/or biofluids, sometimes referred to as a type of "transient" electronics. The results reported here include the kinetics of hydrolysis of Si NMs in biofluids and various aqueous solutions through a range of relevant pH values, ionic concentrations and temperatures, and dependence on dopant types and concentrations. In vitro and in vivo investigations of Si NMs and other transient electronic materials demonstrate biocompatibility and bioresorption, thereby suggesting potential for envisioned applications in active, biodegradable electronic implants.

  6. An in situ x-ray photoelectron spectroscopy study of the initial stages of rf magnetron sputter deposition of indium tin oxide on p-type Si substrate

    SciTech Connect

    Rein, M. H.; Holt, A. O.; Hohmann, M. V.; Klein, A.; Thogersen, A.; Mayandi, J.; Monakhov, E. V.

    2013-01-14

    The interface between indium tin oxide and p-type silicon is studied by in situ X-ray photoelectron spectroscopy (XPS). This is done by performing XPS without breaking vacuum after deposition of ultrathin layers in sequences. Elemental tin and indium are shown to be present at the interface, both after 2 and 10 s of deposition. In addition, the silicon oxide layer at the interface is shown to be composed of mainly silicon suboxides rather than silicon dioxide.

  7. Evaluation of the ion implantation process for production of solar cells from silicon sheet materials

    NASA Technical Reports Server (NTRS)

    Spitzer, M. B.

    1983-01-01

    The objective of this program is the investigation and evaluation of the capabilities of the ion implantation process for the production of photovoltaic cells from a variety of present-day, state-of-the-art, low-cost silicon sheet materials. Task 1 of the program concerns application of ion implantation and furnace annealing to fabrication of cells made from dendritic web silicon. Task 2 comprises the application of ion implantation and pulsed electron beam annealing (PEBA) to cells made from SEMIX, SILSO, heat-exchanger-method (HEM), edge-defined film-fed growth (EFG) and Czochralski (CZ) silicon. The goals of Task 1 comprise an investigation of implantation and anneal processes applied to dendritic web. A further goal is the evaluation of surface passivation and back surface reflector formation. In this way, processes yielding the very highest efficiency can be evaluated. Task 2 seeks to evaluate the use of PEBA for various sheet materials. A comparison of PEBA to thermal annealing will be made for a variety of ion implantation processes.

  8. Preparation of Silicon Nitride Multilayer Ceramic Radome Material and Optimal Design of the Wall Structure

    SciTech Connect

    Chen Fei; Shen Qiang; Zhang Lianmeng

    2008-02-15

    A study of silicon nitride ceramic radomes, which includes preparation of the material and optimal design of the radome wall structure, is presented in this paper. Multilayer radome wall structure with high dielectric constant skins and a low dielectric constant core layer is used for broadband application. As a candidate material for both the skins and core layer, silicon nitride ceramics of controlled dielectric constant in the range 3.0{approx}7.5 were prepared by adding different content of sintering aids such as magnesia, alumina, silica and zirconium phosphate binder and choosing suitable sintering methods. A computer aided design (CAD) for the wall structure of silicon nitride multilayer ceramic radome based on microwave equivalent network method is carried out according to design requirements. By optimizing the thickness of skins and core layer, the power transmission efficiency of such a multilayer Si{sub 3}N{sub 4} ceramic radome is calculated. The calculated results suggest that when the dielectric constant of skins lies in the range 6{approx}7.5 and core layer in the range 3.5{approx}4, the power transmission efficiency is above 85% with frequency of 2{approx}18 GHz while the thickness of skins is less than 0.03{lambda} and the thickness ratio of skins to core layer is less than 1:15.

  9. Minority carrier diffusion lengths and absorption coefficients in silicon sheet material

    NASA Technical Reports Server (NTRS)

    Dumas, K. A.; Swimm, R. T.

    1980-01-01

    Most of the methods which have been developed for the measurement of the minority carrier diffusion length of silicon wafers require that the material have either a Schottky or an ohmic contact. The surface photovoltage (SPV) technique is an exception. The SPV technique could, therefore, become a valuable diagnostic tool in connection with current efforts to develop low-cost processes for the production of solar cells. The technique depends on a knowledge of the optical absorption coefficient. The considered investigation is concerned with a reevaluation of the absorption coefficient as a function of silicon processing. A comparison of absorption coefficient values showed these values to be relatively consistent from sample to sample, and independent of the sample growth method.

  10. Study program to develop and evaluate die and container materials for the growth of silicon ribbons

    NASA Technical Reports Server (NTRS)

    1978-01-01

    Initial sessile drop experiments on SiC, Si3N4 and A1N were conducted. Very promising results were achieved on both SiC and Si3N4 where minimal penetration of these CNTD coatings by molten silicon was observed. More detailed characterization of the CNTD microstructures was accomplished as well as X-ray characterization of the third and fourth candidate materials system sets (i.e. A1N and altered Si3N4). Polished sections of post sessile drop specimens were also prepared and evaluated. The techniques of full scale crucible hot pressing were developed and die grinding development was initiated. The apparatus for measurement of oxygen partial pressure was reconstructed and calibrated. The sessile drop temperature measurement procedure was calibrated for absorption by the pyrex view-port and additional Auger electron analysis was performed at the interface of molten silicon with CNTD Si3N4 and A1N.

  11. Low-background instrumental neutron activation analysis of silicon semiconductor materials

    SciTech Connect

    Smith, A.R.; McDonald, R.J.; Manini, H.; Hurley, D.L.; Norman, E.B.; Vella, M.C.; Odom, R.W.

    1996-01-01

    Samples of silicon wafers, some implanted with zinc, some with memory circuits fabricated on them, and some with oxide coatings were activated with neutrons and analyzed for trace element impurities with low-background germanium gamma-ray spectrometers. Results are presented for these samples as well as for a reference material. Because the silicon matrix activation is so small, reduced spectrometer system background permits the detection of significantly lower impurity concentrations than would otherwise be possible. For the highest efficiency and lowest background system, limits on the lowest levels of trace element concentrations have been measured for wafer sized (1 to 10 g) samples and inferred for bulk sized (365 g) samples. For wafer-sized samples, part-per-trillion detection capabilities are demonstrated for a variety of elemental contaminants important in semiconductor fabrication.

  12. Process feasibility study in support of silicon material Task I. Final report, October 1, 1975-February 6, 1981

    SciTech Connect

    Yaws, C.L.; Li, K.Y.; Hopper, J.R.; Fang, C.S.; Hansen, K.C.

    1981-02-06

    The Low-Cost Solar Array (LSA) Project is directed toward effective cost reduction in the production of silicon for solar cells. Results are presented for process system properties, chemical engineering and economic analyses of the new technologies and processes being developed for the production of lower cost silicon for solar cells. Major physical, thermodynamic and transport property data are reported for the following silicon source and processing chemical materials: silane, silicon tetrachloride, trichlorosilane, dichlorosilane, silicon tetrafluoride, and silicon. The property data are reported for critical temperature, critical pressure, critical volume, vapor pressure, heat of vaporization, heat capacity, density, surface tension, viscosity, thermal conductivity, heat of formation and Gibb's free energy of formation. Chemical engineering analyses involving the preliminary process design of a plant (1000 MT/yr capacity) to produce silicon via the technology under consideration were accomplished for the following processes: UCC silane process for silicon, BCL process for silicon, conventional polysilicon process (Siemens technology), SiI/sub 4/ decomposition process, and DCS process (dichlorosilane).Major activities in chemical engineering analyses include base case conditions, reaction chemistry, process flowsheet, material balance, energy balance, property data, equipment design, major equipment list, production labor and forward for economic analysis. The process design package provides detailed data for raw materials, utilities, major process equipment and production labor requirements necessary for polysilicon production in each process. Using detailed data from the process design package, economic analyses for a 1000 MT/yr silicon plant were accomplished. Primary results from the economic analyses included plant capital investment and product cost. Results are presented and discussed. (WHK)

  13. Evaluation of the Elastic Properties of Thirteen Silicone Interocclusal Recording Materials

    PubMed Central

    Zietek, Marek

    2016-01-01

    Background. Addition silicones are popular as dental impression materials and are used in bite registration procedures. Objective. This study aimed to compare the postsetting elasticities and other mechanical properties of thirteen addition silicone interocclusal recording materials. Materials and Methods. The following materials were investigated: Colorbite D, Futar D, Genie Bite, Jet Blue Bite fast, Memoreg 2, O-Bite, Occlufast Rock, Omni-Bite Plus, Regidur i, Registrado X-tra, Regofix transparent, StoneBite, and Variotime Bite. Thirty specimens of each material were tested. The elasticities and strengths of the materials were measured with a universal testing machine, and computer software was used to determine the E-moduli, ultimate tensile strengths, and ultimate elongations of the specimens. Results. The results were subjected to statistical analysis using the Kruskal-Wallis test (p ≤ 0.05). The statistics revealed that the mean E-modulus values varied significantly across the materials (p = 0.000) and were highest for the StoneBite and Registrado X-tra and lowest for the Regofix transparent. The ultimate tensile strengths were highest for the Regofix transparent and Registrado X-tra (p = 0.000) and lowest for the Jet Blue Bite fast and Memoreg 2 (p = 0.000). The elongation percentages at the point of breaking varied significantly across the materials (p = 0.000); the lowest value was observed for the StoneBite, whereas the Regofix transparent nearly doubled original length. Conclusions. The authors concluded that materials with the high E-moduli and great ultimate tensile strengths may be most useful clinically. Registrado X-tra and StoneBite best met these criteria. PMID:27747239

  14. Basic principles for rational design of high-performance nanostructured silicon-based thermoelectric materials.

    PubMed

    Yang, Chun Cheng; Li, Sean

    2011-12-23

    Recently, nanostructured silicon-based thermoelectric materials have drawn great attention owing to their excellent thermoelectric performance in the temperature range around 450 °C, which is eminently applicable for concentrated solar thermal technology. In this work, a unified nanothermodynamic model is developed to investigate the predominant factors that determine the lattice thermal conductivity of nanocrystalline, nanoporous, and nanostructured bulk Si. A systematic study shows that the thermoelectric performance of these materials can be substantially enhanced by the following three basic principles: 1) artificial manipulation and optimization of roughness with surface/interface patterning/engineering; 2) grain-size reduction with innovative fabrication techniques in a controllable fashion; and 3) optimization of material parameters, such as bulk solid-vapor transition entropy, bulk vibrational entropy, dimensionality, and porosity, to decrease the lattice thermal conductivity. These principles may be used to rationally design novel nanostructured Si-based thermoelectric materials for renewable energy applications.

  15. Reaction bonded silicon carbide material characteristics as related to its use in high power laser systems

    NASA Astrophysics Data System (ADS)

    Pitschman, Matthew; Miller, Travis; Hedges, Alan R.; Rummel, Steve

    2014-09-01

    Reaction bonded silicon carbide (RB SiC) is a durable material that is well-suited for use as a high power laser mirror substrate. The reaction bonded material has a low mass density, a high Young's Modulus, good thermal conductivity, and a very low coefficient of thermal expansion. All of these properties are beneficial in mirror substrates used in multikilowatt lasers. In conjunction with the development of RB SiC, special polishing processes, fabrication processes, and coatings have also been developed. In this paper we will present a comparison of the material properties of RB SiC and other mirror materials currently used in high power lasers. A brief overview of the critical fabrication and coating processes will also be reviewed. Finally, we will present thermal heat load test data showing the surface deformation of various high power mirrors used under heat loads typically found in laser systems operating at average powers greater than 10 kilowatts.

  16. Thermoelectric materials and methods for synthesis thereof

    DOEpatents

    Ren, Zhifeng; Zhang, Qinyong; Zhang, Qian; Chen, Gang

    2015-08-04

    Materials having improved thermoelectric properties are disclosed. In some embodiments, lead telluride/selenide based materials with improved figure of merit and mechanical properties are disclosed. In some embodiments, the lead telluride/selenide based materials of the present disclosure are p-type thermoelectric materials formed by adding sodium (Na), silicon (Si) or both to thallium doped lead telluride materials. In some embodiments, the lead telluride/selenide based materials are formed by doping lead telluride/selenides with potassium.

  17. Improvement in thermoelectric power factor of mechanically alloyed p-type SiGe by incorporation of TiB2

    NASA Astrophysics Data System (ADS)

    Ahmad, Sajid; Dubey, K.; Bhattacharya, Shovit; Basu, Ranita; Bhatt, Ranu; Bohra, A. K.; Singh, Ajay; Aswal, D. K.; Gupta, S. K.

    2016-05-01

    Nearly 60% of the world's useful energy is wasted as heat and recovering a fraction of this waste heat by converting it as useful electrical power is an important area of research[1]. Thermoelectric power generators (TEG) are solid state devices which converts heat into electricity. TEG consists of n and p-type thermoelements connected electrically in series and thermally in parallel[2]. Silicon germanium (SiGe) alloy is one of the conventional high temperature thermoelectric materials and is being used in radio-isotopes based thermoelectric power generators for deep space exploration programs.Temperature (T) dependence of thermoelectric (TE) properties of p-type SiGe and p-type SiGe-x wt.%TiB2 (x=6,8,10%) nanocomposite materials has been studied with in the temperature range of 300 K to 1100 K. It is observed that there is an improvement in the power factor (α2/ρ) of SiGe alloy on addition of TiB2 upto 8 wt.% that is mainly due to increase in the Seebeck coefficient (α) and electrical conductivity (σ) of the alloy.

  18. Acoustic characterization of polyvinyl chloride and self-healing silicone as phantom materials

    NASA Astrophysics Data System (ADS)

    Ceh, Dennis; Peters, Terry M.; Chen, Elvis C. S.

    2015-03-01

    Phantoms are physical constructs used in procedure planning, training, medical imaging research, and machine calibration. Depending on the application, the material a phantom is made out of is very important. With ultrasound imaging, phantom materials used need to have similar acoustic properties, specifically speed of sound and attenuation, as a specified tissue. Phantoms used with needle insertion require a material with a similar tensile strength as tissue and, if possible, the ability to self heal increasing its overall lifespan. Soft polyvinyl chloride (PVC) and silicone were tested as possible needle insertion phantom materials. Acoustic characteristics were determined using a time of flight technique, where a pulse was passed through a sample contained in a water bath. The speed of sound and attenuation were both determined manually and through spectral analysis. Soft PVC was determined to have a speed of sound of approximately 1395 m/s and attenuation of 0.441 dB/cm (at 1 MHz). For the silicone mixture, the respective speed of sound values was within a range of 964.7 m/s and 1250.0 m/s with an attenuation of 0.547 dB/cm (at 1 MHz).

  19. Evaluation of selected chemical processes for production of low-cost silicon phase 2. silicon material task, low-cost silicon solar array project

    NASA Technical Reports Server (NTRS)

    Blocher, J. M., Jr.; Browning, M. F.; Rose, E. E.; Thompson, W. B.; Schmitt, W. A.; Fippin, J. S.; Kidd, R. W.; Liu, C. Y.; Kerbler, P. S.; Ackley, W. R.

    1978-01-01

    Progress from October 1, 1977, through December 31, 1977, is reported in the design of the 50 MT/year experimental facility for the preparation of high purity silicon by the zinc vapor reduction of silicon tetrachloride in a fluidized bed of seed particles to form a free flowing granular product.

  20. Slicing of silicon into sheet material: Silicon sheet growth development for the large area silicon sheet task of the Low Cost Silicon Solar Array project

    NASA Technical Reports Server (NTRS)

    Fleming, J. R.

    1978-01-01

    The limits of blade tolerance were defined. The standard blades are T-2 thickness tolerance. Good results were obtained by using a slurry fluid consisting of mineral oil and a lubricity additive. Adjustments of the formulation and fine tuning of the cutting process with the new fluid are necessary. Test results and consultation indicate that the blade breakage encountered with water based slurries is unavoidable. Two full capacity (974 wafer) runs were made on the large prototype saw. Both runs resulted in extremely low yield. However, the reasons for the low yield were lack of proper technique rather than problems with machine function. The test on the effect of amount of material etched off of an as-sawn wafer on solar cell efficiency were completed. The results agree with previous work at JPL in that the minimum material removed per side that gives maximum efficiency is on the order of 10 microns.

  1. Materials and fabrication sequences for water soluble silicon integrated circuits at the 90 nm node

    SciTech Connect

    Yin, Lan; Harburg, Daniel V.; Rogers, John A.; Bozler, Carl; Omenetto, Fiorenzo

    2015-01-05

    Tungsten interconnects in silicon integrated circuits built at the 90 nm node with releasable configurations on silicon on insulator wafers serve as the basis for advanced forms of water-soluble electronics. These physically transient systems have potential uses in applications that range from temporary biomedical implants to zero-waste environmental sensors. Systematic experimental studies and modeling efforts reveal essential aspects of electrical performance in field effect transistors and complementary ring oscillators with as many as 499 stages. Accelerated tests reveal timescales for dissolution of the various constituent materials, including tungsten, silicon, and silicon dioxide. The results demonstrate that silicon complementary metal-oxide-semiconductor circuits formed with tungsten interconnects in foundry-compatible fabrication processes can serve as a path to high performance, mass-produced transient electronic systems.

  2. Study of the Effects of Impurities on the Properties of Silicon Materials and Performance of Silicon Solar Cell

    NASA Technical Reports Server (NTRS)

    Sah, C. T.

    1979-01-01

    Numerical solutions were obtained from the exact one dimensional transmission line circuit model to study the following effects on the terrestrial performance of silicon solar cells: interband Auger recombination; surface recombination at the contact interfaces; enhanced metallic impurity solubility; diffusion profiles; and defect-impurity recombination centers. Thermal recombination parameters of titanium impurity in silicon were estimated from recent experimental data. Based on those parameters, computer model calculations showed that titanium concentration must be kept below 6x10 to the 12th power Ti/cu cm in order to achieve 16% AM1 efficiency in a silicon solar cell of 250 micrometers thick and 1.5 ohm-cm resistivity.

  3. p-Type semiconducting nickel oxide as an efficiency-enhancing anodal interfacial layer in bulk heterojunction solar cells

    SciTech Connect

    Irwin, Michael D; Buchholz, Donald B; Marks, Tobin J; Chang, Robert P. H.

    2014-11-25

    The present invention, in one aspect, relates to a solar cell. In one embodiment, the solar cell includes an anode, a p-type semiconductor layer formed on the anode, and an active organic layer formed on the p-type semiconductor layer, where the active organic layer has an electron-donating organic material and an electron-accepting organic material.

  4. Convergence of valence bands for high thermoelectric performance for p-type InN

    NASA Astrophysics Data System (ADS)

    Li, Hai-Zhu; Li, Ruo-Ping; Liu, Jun-Hui; Huang, Ming-Ju

    2015-12-01

    Band engineering to converge the bands to achieve high valley degeneracy is one of effective approaches for designing ideal thermoelectric materials. Convergence of many valleys in the valence band may lead to a high Seebeck coefficient, and induce promising thermoelectric performance of p-type InN. In the current work, we have systematically investigated the electronic structure and thermoelectric performance of wurtzite InN by using the density functional theory combined with semiclassical Boltzmann transport theory. Form the results, it can be found that intrinsic InN has a large Seebeck coefficient (254 μV/K) and the largest value of ZeT is 0.77. The transport properties of p-type InN are better than that of n-type one at the optimum carrier concentration, which mainly due to the large Seebeck coefficient for p-type InN, although the electrical conductivity of n-type InN is larger than that of p-type one. We found that the larger Seebeck coefficient for p-type InN may originate from the large valley degeneracy in the valence band. Moreover, the low minimum lattice thermal conductivity for InN is one key factor to become a good thermoelectric material. Therefore, p-type InN could be a potential material for further applications in the thermoelectric area.

  5. The temperature-dependent coefficient of thermal expansion of p-type Ce0.9Fe3.5Co0.5Sb12 and n-type Co0.95Pd0.05Te0.05Sb3 skutterudite thermoelectric materials

    SciTech Connect

    Schmidt, Robert; Case, Eldon D; Ni, Jennifer E.; Sakamoto, Jeffrey; Trejo, Rosa M; Lara-Curzio, Edgar; Payzant, E Andrew; Kirkham, Melanie J; Meisner, Roberta Ann

    2012-01-01

    During waste heat recovery applications, thermoelectric (TE) materials experience thermal gradients and thermal transients, which produce stresses that scale with the TE material's coefficient of thermal expansion (CTE). Thus, the temperature-dependent CTE is an important parameter for the design of mechanically robust TE generators. For three skutterudite thermoelectric compositions, n-type Co{sub 0.95}Pd{sub 0.05}Te{sub 0.05}Sb{sub 3} (with and without 0.1 at. % cerium doping) and p-type Ce{sub 0.9}Fe{sub 3.5}Co{sub 0.5}Sb{sub 12}, the CTE was measured using two methods, i.e. X-ray diffraction on powder and bulk specimens and dilatometry on bulk specimens. Each bulk specimen was hot pressed using powders milled from cast ingots. Between 300 K and 600 K, the mean CTE values were 9.8-10.3 x 10{sup -6} K{sup -1} for the non-cerium-doped n-type, 11.6 x 10{sup -6} K{sup -1} for the 0.1 at. % cerium-doped n-type and from 12.7 to 13.3 x 10{sup -6} K{sup -1} for the p-type. In the literature, similar CTE values are reported for other Sb-based skutterudites. For temperatures >600 K, an unrecovered dilatational strain (perhaps due to bloating) was observed, which may impact applications. Also, the submicron particle sizes generated by wet milling were pyrophoric; thus, during both processing and characterization, exposure of the powders to oxygen should be limited.

  6. Intensifying the Casimir force between two silicon substrates within three different layers of materials

    NASA Astrophysics Data System (ADS)

    Seyedzahedi, A.; Moradian, A.; Setare, M. R.

    2016-04-01

    We investigate the Casimir force for a system composed of two thick slabs as substrates within three different homogeneous layers. We use the scattering approach along with the Matsubara formalism in order to calculate the Casimir force at finite temperature. First, we focus on constructing the reflection matrices and then we calculate the Casimir force for a water-lipid system. According to the conventional use of silicon as a substrate, we apply the formalism to calculate the Casimir force for layers of Au, VO2, mica, KCl and foam rubber on the thick slabs of silicon. Afterwards, introducing an increasing factor, we compare our results with Lifshitz force in the vacuum between two semispaces of silicon in order to illustrate the influence of the layers on intensifying the Casimir force. We also calculate the Casimir force between two slabs of the forementioned materials with finite thicknesses to indicate the substrate's role in increasing the obtained Casimir force. Our simple calculation is interesting since one can extend it along with the Rigorous Coupled Wave Analysis to systems containing inhomogeneous layers as good candidates for designing nanomechanical devices.

  7. Design and evaluation of carbon nanofiber and silicon materials for neural implant applications

    NASA Astrophysics Data System (ADS)

    McKenzie, Janice L.

    Reduction of glial scar tissue around central nervous system implants is necessary for improved efficacy in chronic applications. Design of materials that possess tunable properties inspired by native biological tissue and elucidation of pertinent cellular interactions with these materials was the motivation for this study. Since nanoscale carbon fibers possess the fundamental dimensional similarities to biological tissue and have attractive material properties needed for neural biomaterial implants, this present study explored cytocompatibility of these materials as well as modifications to traditionally used silicon. On silicon materials, results indicated that nanoscale surface features reduced astrocyte functions, and could be used to guide neurite extension from PC12 cells. Similarly, it was determined that astrocyte functions (key cells in glial scar tissue formation) were reduced on smaller diameter carbon fibers (125 nm or less) while PC12 neurite extension was enhanced on smaller diameter carbon fibers (100 nm or less). Further studies implicated laminin adsorption as a key mechanism in enhancing astrocyte adhesion to larger diameter fibers and at the same time encouraging neurite extension on smaller diameter fibers. Polycarbonate urethane (PCU) was then used as a matrix material for the smaller diameter carbon fibers (100 and 60 nm). These composites proved very versatile since electrical and mechanical properties as well as cell functions and directionality could be influenced by changing bulk and surface composition and features of these matrices. When these composites were modified to be smooth at the micronscale and only rough at the nanoscale, P19 cells actually submerged philopodia, extensions, or whole cells bodies beneath the PCU in order to interact with the carbon nanofibers. These carbon nanofiber composites that have been formulated are a promising material to coat neural probes and thereby enhance functionality at the tissue interface. This

  8. Effect of Projectile Materials on Foreign Object Damage of a Gas-Turbine Grade Silicon Nitride

    NASA Technical Reports Server (NTRS)

    Choi, Sung R.; Racz, Zsolt; Bhatt, Ramakrishna T.; Brewer, David N.; Gyekenyesi, John P.

    2005-01-01

    Foreign object damage (FOD) behavior of AS800 silicon nitride was determined using four different projectile materials at ambient temperature. The target test specimens rigidly supported were impacted at their centers by spherical projectiles with a diameter of 1.59 mm. Four different types of projectiles were used including hardened steel balls, annealed steel balls, silicon nitride balls, and brass balls. Post-impact strength of each target specimen impacted was determined as a function of impact velocity to better understand the severity of local impact damage. The critical impact velocity where target specimens fail upon impact was highest with brass balls, lowest with ceramic ball, and intermediate with annealed and hardened steel balls. Degree of strength degradation upon impact followed the same order as in the critical impact velocity with respect to projectile materials. For steel balls, hardened projectiles yielded more significant impact damage than annealed counterparts. The most important material parameter affecting FOD was identified as hardness of projectiles and was correlated in terms of critical impact velocity, impact deformation, and impact load.

  9. Interactions of efficiency and material requirements for terrestrial silicon solar cells

    NASA Technical Reports Server (NTRS)

    Bowler, D. L.; Wolf, M.

    1980-01-01

    The transport velocity transformation method was used to analyze solar cell designs to determine optimum cell structures. It was found that low resistivity materials should be used up to the onset of Auger recombination; a properly designed three-layer structure permits base region approaching an ideal device in performance; and that higher resistivity front regions will need more sophisticated grid metallization structures than those used now. It was concluded that new features will provide idealized silicon cell structures yielding airmass 1 efficiencies in the 24-26.5% range, with real efficiencies near 22%.

  10. Mechanical strength of the silicon carbide-bearing materials under cyclic loading

    SciTech Connect

    Babaev, E.I.; Berdichevskii, I.M.; Kozlovskii, L.V.; Mei, E.P.; Rozhkova, R.A.

    1987-03-01

    The authors seek to optimize the firing process for porcelain both for the resulting properties of the porcelain and for the thermal efficiency of the furnace by finding a structural furnace material which will withstand the designated optimal firing regime. To this end they select and test a silicon carbide refractory for its ultimate flexural and compression strength and its resistance to fracture under thermal cycling and stress conditions.In actual service the refractory is found to increase the service life and reduce the frequency of maintenance of the furnace.

  11. Silicon-based elementary particle tracking system: Materials science and mechanical engineering design

    SciTech Connect

    Miller, W.O.; Gamble, M.T.; Thompson, T.C.; Hanlon, J.A.

    1993-01-01

    Research and development of the mechanical, cooling, and structural design aspects of a silicon detector-based elementary particle tracking system has been performed. Achieving stringent system precision, stability, and mass requirements necessitated the use of graphite fiber-reinforced cyanate-ester (C-E) resins. Mechanical test results of the effects of butane, ionizing radiation, and a combination of both on the mechanical properties of these materials are presented, as well as progress on developing compression molding of an ultralightweight graphite composite ring structure and TV holography-based noninvasive evaluation.

  12. Silicon-based elementary particle tracking system: Materials science and mechanical engineering design

    SciTech Connect

    Miller, W.O.; Gamble, M.T.; Thompson, T.C.; Hanlon, J.A.

    1993-05-01

    Research and development of the mechanical, cooling, and structural design aspects of a silicon detector-based elementary particle tracking system has been performed. Achieving stringent system precision, stability, and mass requirements necessitated the use of graphite fiber-reinforced cyanate-ester (C-E) resins. Mechanical test results of the effects of butane, ionizing radiation, and a combination of both on the mechanical properties of these materials are presented, as well as progress on developing compression molding of an ultralightweight graphite composite ring structure and TV holography-based noninvasive evaluation.

  13. Study Program to Develop and Evaluate Die and Container Materials for the Growth of Silicon Ribbons

    NASA Technical Reports Server (NTRS)

    Ounby, P. D.; Yu, B. B.; Barsoum, M. W.

    1979-01-01

    The completion of a major hardware delivery milestone was accomplished with the delivery of three CNTD Si3N4 coated hot pressed Si3N4 crucibles. A limited characterization of the coating was performed at MRL prior to delivery. The coatings were fine grained alpha - Si3N4. It was determined that a two piece die design is required. The importance of the role of oxygen in influencing the attack of the CNTD materials by molten silicon was demonstrated. The stability is greatly enhanced by maintaining the oxygen partial pressure near or below the Si + O2 = SiO2 equilibrium.

  14. High-Columbic-Efficiency Lithium Battery Based on Silicon Particle Materials

    NASA Astrophysics Data System (ADS)

    Zhang, Junying; Zhang, Chunqian; Wu, Shouming; Zhang, Xu; Li, Chuanbo; Xue, Chunlai; Cheng, Buwen

    2015-10-01

    Micro-sized polycrystalline silicon particles were used as anode materials of lithium-ion battery. The columbic efficiency of the first cycle reached a relatively high value of 91.8 % after prelithiation and increased to 99 % in the second cycle. Furthermore, columbic efficiency remained above 99 % for up to 280+ cycles. The excellent performances of the batteries were the results of the use of a proper binder to protect the electrode from cracking and the application of a suitable conductive agent to provide an efficient conductive channel. The good performance was also significantly attributed to the electrolyte in the packaging process.

  15. A comparison of dimensional accuracy between three different addition cured silicone impression materials.

    PubMed

    Forrester-Baker, L; Seymour, K G; Samarawickrama, D; Zou, L; Cherukara, G; Patel, M

    2005-06-01

    Ten impressions of a metal implant abutment were made with each of three addition-cured silicone impression materials. Using the technique of co-ordinate metrology, the shoulder region of the abutment and corresponding regions of both impressions and dies made from these impressions were scanned and measured. Comparison of these measurements indicated that the mean dimension measured from the shoulder region for each group of impression materials was significantly different from those taken from the original metal implant abutment. However, when these impressions were cast in a gypsum based die material, none of the measured dimensions taken from the casts were significantly different from those taken from the original metal implant abutment. Thus, any change in measured dimensions occurring during impression making, was compensated for in some way by the casting process. PMID:16011234

  16. Laser annealing of amorphous/poly: Silicon solar cell material flight experiment

    NASA Technical Reports Server (NTRS)

    Cole, Eric E.

    1990-01-01

    The preliminary design proposed for the microelectronics materials processing equipment is presented. An overall mission profile, description of all processing steps, analysis methods and measurement techniques, data acquisition and storage, and a preview of the experimental hardware are included. The goal of the project is to investigate the viability of material processing of semiconductor microelectronics materials in a micro-gravity environment. The two key processes are examined: (1) Rapid Thermal Annealing (RTA) of semiconductor thin films and damaged solar cells, and (2) thin film deposition using a filament evaporator. The RTA process will be used to obtain higher quality crystalline properties from amorphous/poly-silicon films. RTA methods can also be used to repair radiation-damaged solar cells. On earth this technique is commonly used to anneal semiconductor films after ion-implantation. The damage to the crystal lattice is similar to the defects found in solar cells which have been exposed to high-energy particle bombardment.

  17. Optical and Scanning Electron Microscopy of the Materials International Space Station Experiment (MISSE) Spacecraft Silicone Experiment

    NASA Technical Reports Server (NTRS)

    Hung, Ching-cheh; de Groh, Kim K.; Banks, Bruce A.

    2012-01-01

    Under a microscope, atomic oxygen (AO) exposed silicone surfaces are crazed and seen as "islands" separated by numerous crack lines, much analogous to mud-tile cracks. This research characterized and compared the degree of AO degradation of silicones by analyzing optical microscope images of samples exposed to low Earth orbit (LEO) AO as part of the Spacecraft Silicone Experiment. The Spacecraft Silicone Experiment consisted of eight DC 93-500 silicone samples exposed to eight different AO fluence levels (ranged from 1.46 to 8.43 10(exp 21) atoms/sq cm) during two different Materials International Space Station Experiment (MISSE) missions. Image analysis software was used to analyze images taken using a digital camera. To describe the morphological degradation of each AO exposed flight sample, three different parameters were selected and estimated: (1) average area of islands was determined and found to be in the 1000 to 3100 sq mm range; (2) total length of crack lines per unit area of the sample surface were determined and found to be in the range of 27 to 59 mm of crack length per sq mm of sample surface; and (3) the fraction of sample surface area that is occupied by crack lines was determined and found to be in the 25 to 56 percent range. In addition, average crack width can be estimated from crack length and crack area measurements and was calculated to be about 10 mm. Among the parameters studied, the fraction of sample surface area that is occupied by crack lines is believed to be most useful in characterizing the degree of silicone conversion to silicates by AO because its value steadily increases with increasing fluence over the entire fluence range. A series of SEM images from the eight samples exposed to different AO fluences suggest a complex sequence of surface stress due to surface shrinkage and crack formation, followed by re-distribution of stress and shrinking rate on the sample surface. Energy dispersive spectra (EDS) indicated that upon AO

  18. Development of an aluminum nitride-silicon carbide material set for high-temperature sensor applications

    NASA Astrophysics Data System (ADS)

    Griffin, Benjamin A.; Habermehl, Scott D.; Clews, Peggy J.

    2014-06-01

    A number of important energy and defense-related applications would benefit from sensors capable of withstanding extreme temperatures (>300°C). Examples include sensors for automobile engines, gas turbines, nuclear and coal power plants, and petroleum and geothermal well drilling. Military applications, such as hypersonic flight research, would also benefit from sensors capable of 1000°C. Silicon carbide (SiC) has long been recognized as a promising material for harsh environment sensors and electronics because it has the highest mechanical strength of semiconductors with the exception of diamond and its upper temperature limit exceeds 2500°C, where it sublimates rather than melts. Yet today, many advanced SiC MEMS are limited to lower temperatures because they are made from SiC films deposited on silicon wafers. Other limitations arise from sensor transduction by measuring changes in capacitance or resistance, which require biasing or modulation schemes that can with- stand elevated temperatures. We are circumventing these issues by developing sensing structures directly on SiC wafers using SiC and piezoelectric aluminum nitride (AlN) thin films. SiC and AlN are a promising material combination due to their high thermal, electrical, and mechanical strength and closely matched coefficients of thermal expansion. AlN is also a non-ferroelectric piezoelectric material, enabling piezoelectric transduction at temperatures exceeding 1000°C. In this paper, the challenges of incorporating these two materials into a compatible MEMS fabrication process are presented. The current progress and initial measurements of the fabrication process are shown. The future direction and the need for further investigation of the material set are addressed.

  19. On the origin of dislocation loops in irradiated materials: A point of view from silicon

    NASA Astrophysics Data System (ADS)

    Claverie, Alain; Cherkashin, Nikolay

    2016-05-01

    Numerous dislocation loops are often observed in irradiated and nuclear materials, affecting many physical properties. The understanding of their origin and of their growth mechanism remains unclear rendering all modeling efforts elusive. In this paper, we remind the knowledge which has been gained during the last 20 years on the formation and growth of extrinsic dislocations loops in irradiated/implanted silicon. From the compilation of a large number of experimental results, a unified picture describing the thermal evolution of interstitial defects, from the di-interstitial stable at room temperature, to "magic-size" clusters then to rod-like defects and finally to large dislocation loops of two types has emerged. All these defects grow by Ostwald ripening, i.e. by interchanging the interstitial atoms they are composed of, and transform from one to the other driven by the resulting reduction of the defect formation energy. A model has been proposed and is now integrated into process simulators which quantitatively describes the thermal evolution of all these defects, based on pertinent formation energies. The influence of the proximity of free surfaces or other recombining interfaces can be integrated, allowing simulating the possible dissolution of defects. It is suggested that, beyond silicon, the same type of scenario may take place in many materials. Dislocation loops are just one, easily detectable among many, type of defects which forms during the growth of self-interstitials. They do not nucleate but result from the growth and transformation of smaller defects.

  20. Material strength and inelastic deformation of silicon carbide under shock wave compression

    SciTech Connect

    Feng, R.; Raiser, G.F.; Gupta, Y.M.

    1998-01-01

    In-material, lateral, manganin foil gauge measurements were obtained in dense polycrystalline silicon carbide (SiC) shocked to peak longitudinal stresses ranging from 10{endash}24 GPa. The lateral gauge data were analyzed to determine the lateral stresses in the shocked SiC and the results were checked for self-consistency through dynamic two-dimensional computations. Over the stress range examined, the shocked SiC has an extremely high strength: the maximum shear stress supported by the material in the shocked state increases from 4.5 GPa at the Hugoniot elastic limit (HEL) of the material (11.5 GPa) to 7.0 GPa at stresses approximately twice the HEL. The latter value is 3.7{percent} of the shear modulus of the material. The elastic{endash}inelastic transition in the shocked SiC is nearly indistinctive. At stresses beyond twice the HEL, the data suggest a gradual softening with increasing shock compression. The post-HEL material strength evolution resembles neither catastrophic failure due to massive cracking nor classical plasticity response. Stress confinement, inherent in plane shock wave compression, contributes significantly to the observed material response. The results obtained are interpreted qualitatively in terms of an inhomogeneous deformation mechanism involving both in-grain microplasticity and highly confined microfissures. {copyright} {ital 1998 American Institute of Physics.}

  1. Comparative study of dimensional accuracy of different impression techniques using addition silicone impression material.

    PubMed

    Penaflor, C F; Semacio, R C; De Las Alas, L T; Uy, H G

    1998-01-01

    This study compared dimensional accuracy of the single, double with spacer, double with cut-out and double mix impression technique using addition silicone impression material. A typhodont containing Ivorine teeth model with six (6) full-crown tooth preparations were used as the positive control. Two stone replication models for each impression technique were made as test materials. Accuracy of the techniques were assessed by measuring four dimensions on the stone dies poured from the impression of the Ivorine teeth model. Results indicated that most of the measurements for the height, width and diameter slightly decreased and a few increased compared with the Ivorine teeth model. The double with cut-out and double mix technique presents the least difference from the master model as compared to the two latter impression techniques. PMID:10202524

  2. Electrodeposited copper front metallization for silicon heterojunction solar cells: materials and processes

    SciTech Connect

    Geissbühler, J.; Martin de Nicolas, S.; Faes, A.; Lachowicz, A.; Tomasi, A.; Paviet-Salomon, B.; Lachenal, D.; Papet, P.; Badel, N.; Barraud, L.; Descoeudres, A.; Despeisse, M.; De Wolf, S.; Ballif, C.

    2014-10-20

    Even though screen-printing of low-temperature silver paste remains the state-of-the-art technique for the front-metallization of SHJ solar cells, recent studies have demonstrated large efficiency improvements when copper-electroplated contacts are used instead of screen-printed ones. However, due to the new materials and the new processes introduced by this technique, it is crucial to individually investigate their compatibility with the SHJ cell structure. In this study, we present a detailed analysis of how the performances of SHJ devices may be modified by these new materials and processes. First, effects on the amorphous silicon (a-Si:H) passivation have been studied for various processes such as DI water rinsing, dips in a copper removal solution and direct evaporation of copper on the a-Si:H. Finally, copper electroplating technique has been adapted in order to be applied to more complex cell structures such as high-efficiency IBC-SHJ.

  3. Contactless Spectral-dependent Charge Carrier Lifetime Measurements in Silicon Photovoltaic Materials

    NASA Astrophysics Data System (ADS)

    Roller, John; Hamadani, Behrang; Dagenais, Mario

    Charge carrier lifetime measurements in bulk or unfinished photovoltaic (PV) materials allow for a more accurate estimate of power conversion efficiency in completed solar cells. In this work, carrier lifetimes in PV-grade silicon wafers are obtained by way of quasi-steady state photoconductance measurements. These measurements use a contactless RF system coupled with varying narrow spectrum input LEDs, ranging in wavelength from 460 nm to 1030 nm. Spectral dependent lifetime measurements allow for determination of bulk and surface properties of the material, including the intrinsic bulk lifetime and the surface recombination velocity. The effective lifetimes are fit to an analytical physics-based model to determine the desired parameters. Passivated and non-passivated samples are both studied and are shown to have good agreement with the theoretical model.

  4. Rolling-element fatigue life of silicon nitride balls. [as compared to that of steel, ceramic, and cermet materials

    NASA Technical Reports Server (NTRS)

    Parker, R. J.; Zaretsky, E. V.

    1974-01-01

    The five-ball fatigue tester was used to evaluate silicon nitride as a rolling-element bearing material. Results indicate that hot-pressed silicon nitride running against steel may be expected to yield fatigue lives comparable to or greater than those of bearing quality steel running against steel at stress levels typical rolling-element bearing application. The fatigue life of hot-pressed silicon nitride is considerably greater than that of any ceramic or cermet tested. Computer analysis indicates that there is no improvement in the lives of 120-mm-bore angular--contact ball bearings of the same geometry operating at DN values from 2 to 4 million where hot-pressed silicon nitride balls are used in place of steel balls.

  5. An integrated driving circuit implemented with p-type LTPS TFTs for AMOLED

    NASA Astrophysics Data System (ADS)

    Zhao, Li-Qing; Wu, Chun-Ya; Hao, Da-Shou; Yao, Ying; Meng, Zhi-Guo; Xiong, Shao-Zhen

    2009-03-01

    Based on the technology of low temperature poly silicon thin film transistors (poly-Si-TFTs), a novel p-type TFT AMOLED panel with self-scanned driving circuit is introduced in this paper. A shift register formed with novel p-type TFTs is proposed to realize the gate driver. A flip-latch cooperated with the shift register is designed to conduct the data writing. In order to verify the validity of the proposed design, the circuits are simulated with SILVACO TCAD tools, using the MODEL in which the parameters of LTPS TFTs were extracted from the LTPS TFTs made in our lab. The simulation results indicate that the circuit can fulfill the driving function.

  6. Comparison of amorphous silicon absorber materials: Light-induced degradation and solar cell efficiency

    NASA Astrophysics Data System (ADS)

    Stuckelberger, M.; Despeisse, M.; Bugnon, G.; Schüttauf, J.-W.; Haug, F.-J.; Ballif, C.

    2013-10-01

    Several amorphous silicon (a-Si:H) deposition conditions have been reported to produce films that degrade least under light soaking when incorporated into a-Si:H solar cells. However, a systematic comparison of these a-Si:H materials has never been presented. In the present study, different plasma-enhanced chemical vapor deposition conditions, yielding standard low-pressure VHF a-Si:H, protocrystalline, polymorphous, and high-pressure RF a-Si:H materials, are compared with respect to their optical properties and their behavior when incorporated into single-junction solar cells. A wide deposition parameter space has been explored in the same deposition system varying hydrogen dilution, deposition pressure, temperature, frequency, and power. From the physics of layer growth, to layer properties, to solar cell performance and light-induced degradation, a consistent picture of a-Si:H materials that are currently used for a-Si:H solar cells emerges. The applications of these materials in single-junction, tandem, and triple-junction solar cells are discussed, as well as their deposition compatibility with rough substrates, taking into account aspects of voltage, current, and charge collection. In sum, this contributes to answering the question, "Which material is best for which type of solar cell?"

  7. Flexible Protocrystalline Silicon Solar Cells with Amorphous Buffer Layer

    NASA Astrophysics Data System (ADS)

    Ishikawa, Yasuaki; Schubert, Markus B.

    2006-09-01

    A low deposition temperature of 110 °C is mandatory for directly growing amorphous-silicon-based solar cells on plastic foil. The optimum absorber material at this low temperature is protocrystalline, i.e., right at the transition between amorphous and crystalline silicon. Polyethylene terephtalate foil of 50 μm thickness form the substrate of our flexible p-i-n single-junction cells. We discuss three peculiar processing techniques for achieving the maximum photovoltaic conversion efficiency of flexible low-temperature solar cells. First, we employ an optimized microcrystalline silicon p-type window layer; second, we use protocrystalline silicon for the i-layer; third, we insert an undoped amorphous silicon buffer layer at the p/i interface. The best flexible cells attain power conversion efficiencies of up to 4.9%.

  8. Liquid phase crystallized silicon on glass: Technology, material quality and back contacted heterojunction solar cells

    NASA Astrophysics Data System (ADS)

    Haschke, Jan; Amkreutz, Daniel; Rech, Bernd

    2016-04-01

    Liquid phase crystallization has emerged as a novel approach to grow large grained polycrystalline silicon films on glass with high electronic quality. In recent years a lot of effort was conducted by different groups to determine and optimize suitable interlayer materials, enhance the crystallographic quality or to improve post crystallization treatments. In this paper, we give an overview on liquid phase crystallization and describe the necessary process steps and discuss their influence on the absorber properties. Available line sources are compared and different interlayer configurations are presented. Furthermore, we present one-dimensional numerical simulations of a rear junction device, considering silicon absorber thicknesses between 1 and 500 µm. We vary the front surface recombination velocity as well as doping density and minority carrier lifetime in the absorber. The simulations suggest that a higher absorber doping density is beneficial for layer thicknesses below 20 µm or when the minority carrier lifetime is short. Finally, we discuss possible routes for device optimization and propose a hybride cell structure to circumvent current limitations in device design.

  9. Fracture properties of polycrystalline silicon - a material for micro-electro-mechanical systems

    SciTech Connect

    Johnson, G.C.; Jones, P.T.

    1995-12-31

    A great deal of research has been performed during the past few years to apply the microfabrication technology used for making integrated circuits to the manufacture of microscopic pressure sensors, accelerometers, and other micro-electro-mechanical systems (MEMS). One result of this work has been the choice of polycrystalline silicon (polysilicon) as a primary structural material employed in MEMS devices, particularly when the polysilicon has been doped with such elements as phosphorus for improved electrical and mechanical properties. As MEMS devices become more relied upon for real world applications, it will be necessary to establish design rules to ensure adequate product lifetimes. However, very little work has been done to deter- mine the failure mechanisms of polysilicon. The work presented here offers an experimental evaluation of the ultimate strength and fracture toughness of polysilicon with regard to the effects of exposure to hydrofluoric acid, a commonly used etchant in MEMS fabrication. A series of micromechanical structures have been designed to measure the strain at fracture and fracture toughness of a thin film. These test structures are patterned onto a thin film of polysilicon covering a silicon wafer using standard microfabrication techniques. Since the structures have dimensions on the order of microns, hundreds of multiple test structures are patterned on a single wafer providing a large amount of statistical data. Results using these structures indicate that prolonged exposure to HF can result in a decrease in the fracture strength of polysilicon.

  10. Progress on the carbothermic production of solar-grade silicon using high-purity starting materials

    SciTech Connect

    Schultz, F.W.; Aulich, H.A.; Fenzi, H.J.; Hecht, M.D.

    1984-05-01

    Solar-grade silicon was produced by carbothermic reduction (CR) in a 70 kW arc-furnace. Silicon suitable for solar cells with an efficiency > 10% was obtained form silicon dioxide of different origin and purified carbon. The importance of a low P- and B-concentration (<10/sup 17/a/cm/sup 3/) in the silicon produced was established. Cells made from CR-Si were successfully processed into modules using conventional technology.

  11. Neutron-irradiation creep of silicon carbide materials beyond the initial transient

    NASA Astrophysics Data System (ADS)

    Koyanagi, Takaaki; Katoh, Yutai; Ozawa, Kazumi; Shimoda, Kazuya; Hinoki, Tatsuya; Snead, Lance L.

    2016-09-01

    Irradiation creep beyond the transient regime was investigated for various silicon carbide (SiC) materials. The materials examined included polycrystalline or monocrystalline high-purity SiC, nanopowder sintered SiC, highly crystalline and near-stoichiometric SiC fibers (including Hi-Nicalon Type S, Tyranno SA3, isotopically-controlled Sylramic and Sylramic-iBN fibers), and a Tyranno SA3 fiber-reinforced SiC matrix composite fabricated through a nano-infiltration transient eutectic phase process. Neutron irradiation experiments for bend stress relaxation tests were conducted at irradiation temperatures ranging from 430 to 1180 °C up to 30 dpa with initial bend stresses of up to ∼1 GPa for the fibers and ∼300 MPa for the other materials. Initial bend stress in the specimens continued to decrease from 1 to 30 dpa. Analysis revealed that (1) the stress exponent of irradiation creep above 1 dpa is approximately unity, (2) the stress normalized creep rate is ∼1 × 10-7 [dpa-1 MPa-1] at 430-750 °C for the range of 1-30 dpa for most polycrystalline SiC materials, and (3) the effects on irradiation creep of initial microstructures-such as grain boundary, crystal orientation, and secondary phases-increase with increasing irradiation temperature.

  12. Effects of Non-equilibrium Solidification on the Material Properties of Brick Silicon for Photovoltaics

    NASA Technical Reports Server (NTRS)

    Regnault, W. F.; Yoo, K. C.; Soltani, P. K.; Johnson, S. M.

    1984-01-01

    Silicon ingot growth technologies like the Ubiquitous Crystallization Process (UCP) are solidified within a shaping crucible. The rate at which heat can be lost from this crucible minus the rate at which heat is input from an external source determines the rate at which crystallization will occur. Occasionally, when the process parameters for solidification are exceeded, the normally large multi-centimeter grain size material assocated with the UCP will break down into regions containing extremely small, millimeter or less, grain size material. Accompanying this breakdown in grain growth is the development of so called sinuous grain boundaries. The breakdown in grain growth which results in this type of small grain structure with sinuous boundaries is usually associated with the rapid crystallization that would accompany a system failure. This suggests that there are limits to the growth velocity that one can obtain and still expect to produce material that would possess good photovoltaic properties. It is the purpose to determine the causes behind the breakdown of this material and what parameters will determine the best rates of solidification.

  13. Investigations of nanocomposite magnetic materials based on the oxides of iron, nickel, cobalt and silicon dioxide

    NASA Astrophysics Data System (ADS)

    Gracheva, Irina E.; Olchowik, Grazyna; Gareev, Kamil G.; Moshnikov, Vyatcheslav A.; Kuznetsov, Vladimir V.; Olchowik, Jan M.

    2013-05-01

    This paper is concerned with the study of magnetic nanocomposites containing silicon, iron, nickel, and cobalt oxides. These materials were produced in the form of thin films based on Fe-Si-O, Ni-Co-Si-O and Fe-Ni-Co-Si-O systems and powders based on Fe-Si-O, Ni-Si-O, Co-Si-O and Fe-Ni-Co-Si-O systems using sol-gel technology, through centrifugation, and deposition of ammonia solution. The morphology and magnetic properties of materials in the form of thin films were studied by using the atomic force microscopy. The phase composition, specific surface area and magnetic properties of materials in the form of powders were studied by using the X-ray phase analysis, thermal desorption, vibrational magnetometry and immittance measurements. The dependencies of the main parameters were derived for the magnetic materials from their structure and manufacturing conditions. Ways to optimise the technological processes were proposed, aimed at reducing the size of the magnetic particles in an amorphous lattice.

  14. Neutron-irradiation creep of silicon carbide materials beyond the initial transient

    DOE PAGESBeta

    Katoh, Yutai; Ozawa, Kazumi; Shimoda, Kazuya; Hinoki, Tatsuya; Snead, Lance Lewis; Koyanagi, Takaaki

    2016-06-04

    Irradiation creep beyond the transient regime was investigated for various silicon carbide (SiC) materials. Here, the materials examined included polycrystalline or monocrystalline high-purity SiC, nanopowder sintered SiC, highly crystalline and near-stoichiometric SiC fibers (including Hi-Nicalon Type S, Tyranno SA3, isotopically-controlled Sylramic and Sylramic-iBN fibers), and a Tyranno SA3 fiber–reinforced SiC matrix composite fabricated through a nano-infiltration transient eutectic phase process. Neutron irradiation experiments for bend stress relaxation tests were conducted at irradiation temperatures ranging from 430 to 1180 °C up to 30 dpa with initial bend stresses of up to ~1 GPa for the fibers and ~300 MPa for themore » other materials. Initial bend stress in the specimens continued to decrease from 1 to 30 dpa. Analysis revealed that (1) the stress exponent of irradiation creep above 1 dpa is approximately unity, (2) the stress normalized creep rate is ~1 × 10–7 [dpa–1 MPa–1] at 430–750 °C for the range of 1–30 dpa for most polycrystalline SiC materials, and (3) the effects on irradiation creep of initial microstructures—such as grain boundary, crystal orientation, and secondary phases—increase with increasing irradiation temperature.« less

  15. Photovoltaic properties of ZnO nanorods/p-type Si heterojunction structures

    PubMed Central

    Witkowski, Bartlomiej Slawomir; Luka, Grzegorz; Wachnicki, Lukasz; Gieraltowska, Sylwia; Kopalko, Krzysztof; Zielony, Eunika; Bieganski, Piotr; Placzek-Popko, Ewa; Godlewski, Marek

    2014-01-01

    Summary Selected properties of photovoltaic (PV) structures based on n-type zinc oxide nanorods grown by a low temperature hydrothermal method on p-type silicon substrates (100) are investigated. PV structures were covered with thin films of Al doped ZnO grown by atomic layer deposition acting as transparent electrodes. The investigated PV structures differ in terms of the shapes and densities of their nanorods. The best response is observed for the structure containing closely-spaced nanorods, which show light conversion efficiency of 3.6%. PMID:24605282

  16. Single Photon Counting UV Solar-Blind Detectors Using Silicon and III-Nitride Materials.

    PubMed

    Nikzad, Shouleh; Hoenk, Michael; Jewell, April D; Hennessy, John J; Carver, Alexander G; Jones, Todd J; Goodsall, Timothy M; Hamden, Erika T; Suvarna, Puneet; Bulmer, J; Shahedipour-Sandvik, F; Charbon, Edoardo; Padmanabhan, Preethi; Hancock, Bruce; Bell, L Douglas

    2016-01-01

    Ultraviolet (UV) studies in astronomy, cosmology, planetary studies, biological and medical applications often require precision detection of faint objects and in many cases require photon-counting detection. We present an overview of two approaches for achieving photon counting in the UV. The first approach involves UV enhancement of photon-counting silicon detectors, including electron multiplying charge-coupled devices and avalanche photodiodes. The approach used here employs molecular beam epitaxy for delta doping and superlattice doping for surface passivation and high UV quantum efficiency. Additional UV enhancements include antireflection (AR) and solar-blind UV bandpass coatings prepared by atomic layer deposition. Quantum efficiency (QE) measurements show QE > 50% in the 100-300 nm range for detectors with simple AR coatings, and QE ≅ 80% at ~206 nm has been shown when more complex AR coatings are used. The second approach is based on avalanche photodiodes in III-nitride materials with high QE and intrinsic solar blindness. PMID:27338399

  17. Single Photon Counting UV Solar-Blind Detectors Using Silicon and III-Nitride Materials

    PubMed Central

    Nikzad, Shouleh; Hoenk, Michael; Jewell, April D.; Hennessy, John J.; Carver, Alexander G.; Jones, Todd J.; Goodsall, Timothy M.; Hamden, Erika T.; Suvarna, Puneet; Bulmer, J.; Shahedipour-Sandvik, F.; Charbon, Edoardo; Padmanabhan, Preethi; Hancock, Bruce; Bell, L. Douglas

    2016-01-01

    Ultraviolet (UV) studies in astronomy, cosmology, planetary studies, biological and medical applications often require precision detection of faint objects and in many cases require photon-counting detection. We present an overview of two approaches for achieving photon counting in the UV. The first approach involves UV enhancement of photon-counting silicon detectors, including electron multiplying charge-coupled devices and avalanche photodiodes. The approach used here employs molecular beam epitaxy for delta doping and superlattice doping for surface passivation and high UV quantum efficiency. Additional UV enhancements include antireflection (AR) and solar-blind UV bandpass coatings prepared by atomic layer deposition. Quantum efficiency (QE) measurements show QE > 50% in the 100–300 nm range for detectors with simple AR coatings, and QE ≅ 80% at ~206 nm has been shown when more complex AR coatings are used. The second approach is based on avalanche photodiodes in III-nitride materials with high QE and intrinsic solar blindness. PMID:27338399

  18. Single Photon Counting UV Solar-Blind Detectors Using Silicon and III-Nitride Materials.

    PubMed

    Nikzad, Shouleh; Hoenk, Michael; Jewell, April D; Hennessy, John J; Carver, Alexander G; Jones, Todd J; Goodsall, Timothy M; Hamden, Erika T; Suvarna, Puneet; Bulmer, J; Shahedipour-Sandvik, F; Charbon, Edoardo; Padmanabhan, Preethi; Hancock, Bruce; Bell, L Douglas

    2016-06-21

    Ultraviolet (UV) studies in astronomy, cosmology, planetary studies, biological and medical applications often require precision detection of faint objects and in many cases require photon-counting detection. We present an overview of two approaches for achieving photon counting in the UV. The first approach involves UV enhancement of photon-counting silicon detectors, including electron multiplying charge-coupled devices and avalanche photodiodes. The approach used here employs molecular beam epitaxy for delta doping and superlattice doping for surface passivation and high UV quantum efficiency. Additional UV enhancements include antireflection (AR) and solar-blind UV bandpass coatings prepared by atomic layer deposition. Quantum efficiency (QE) measurements show QE > 50% in the 100-300 nm range for detectors with simple AR coatings, and QE ≅ 80% at ~206 nm has been shown when more complex AR coatings are used. The second approach is based on avalanche photodiodes in III-nitride materials with high QE and intrinsic solar blindness.

  19. A CMOS compatible Microbulk Micromegas-like detector using silicon oxide as spacer material

    NASA Astrophysics Data System (ADS)

    Blanco Carballo, V. M.; Fransen, M.; van der Graaf, H.; Lu, J.; Schmitz, J.

    2011-02-01

    We present a new Micro Pattern Gaseous Detector (MPGD) fabricated with nonpolymeric materials. The device structure is similar to a Microbulk Micromegas design, consisting of a punctured metal grid supported by a continuous perforated insulating structure. In this detector, the supporting structure is made out of silicon oxide. Devices were tested in He/ iC 4H 10 (80/20) and Ar/ iC 4H 10 (80/20) gas mixtures under 55Fe irradiation. Gas gain of 20,000 and energy resolution below 13% FWHM were achieved. The CMOS compatibility of the fabrication process has been studied in Timepix chips as well as individual 0.13-μm technology CMOS transistors. Complete detectors have been fabricated on top of Timepix chips. In an Ar/ iC 4H 10 (80/20) gas mixture 55Fe decay events were recorded operating the Timepix chip in 2D readout mode.

  20. Graphene encapsulated and SiC reinforced silicon nanowires as an anode material for lithium ion batteries.

    PubMed

    Yang, Yang; Ren, Jian-Guo; Wang, Xin; Chui, Ying-San; Wu, Qi-Hui; Chen, Xianfeng; Zhang, Wenjun

    2013-09-21

    Anode materials play a key role in the performance, in particular the capacity and lifetime, of lithium ion batteries (LIBs). Silicon has been demonstrated to be a promising anode material due to its high specific capacity, but pulverization during cycling and formation of an unstable solid-electrolyte interphase limit its cycle life. Herein, we show that anodes consisting of an active silicon nanowire (Si NW), which is surrounded by a uniform graphene shell and comprises silicon carbide nanocrystals, are capable of serving over 500 cycles in half cells at a high lithium storage capacity of 1650 mA h g(-1). In the anodes, the graphene shell provides a highly-conductive path and prevents direct exposure of Si NWs to electrolytes while the SiC nanocrystals may act as a rigid backbone to retain the integrity of the Si NW in its great deformation process caused by repetitive charging-discharging reactions, resulting in a stable cyclability.

  1. Material requirements for the adoption of unconventional silicon crystal and wafer growth techniques for high-efficiency solar cells

    SciTech Connect

    Hofstetter, Jasmin; del Cañizo, Carlos; Wagner, Hannes; Castellanos, Sergio; Buonassisi, Tonio

    2015-10-15

    Silicon wafers comprise approximately 40% of crystalline silicon module cost and represent an area of great technological innovation potential. Paradoxically, unconventional wafer-growth techniques have thus far failed to displace multicrystalline and Czochralski silicon, despite four decades of innovation. One of the shortcomings of most unconventional materials has been a persistent carrier lifetime deficit in comparison to established wafer technologies, which limits the device efficiency potential. In this perspective article, we review a defect-management framework that has proven successful in enabling millisecond lifetimes in kerfless and cast materials. Control of dislocations and slowly diffusing metal point defects during growth, coupled to effective control of fast-diffusing species during cell processing, is critical to enable high cell efficiencies. As a result, to accelerate the pace of novel wafer development, we discuss approaches to rapidly evaluate the device efficiency potential of unconventional wafers from injection-dependent lifetime measurements.

  2. Material requirements for the adoption of unconventional silicon crystal and wafer growth techniques for high-efficiency solar cells

    DOE PAGESBeta

    Hofstetter, Jasmin; del Cañizo, Carlos; Wagner, Hannes; Castellanos, Sergio; Buonassisi, Tonio

    2015-10-15

    Silicon wafers comprise approximately 40% of crystalline silicon module cost and represent an area of great technological innovation potential. Paradoxically, unconventional wafer-growth techniques have thus far failed to displace multicrystalline and Czochralski silicon, despite four decades of innovation. One of the shortcomings of most unconventional materials has been a persistent carrier lifetime deficit in comparison to established wafer technologies, which limits the device efficiency potential. In this perspective article, we review a defect-management framework that has proven successful in enabling millisecond lifetimes in kerfless and cast materials. Control of dislocations and slowly diffusing metal point defects during growth, coupled tomore » effective control of fast-diffusing species during cell processing, is critical to enable high cell efficiencies. As a result, to accelerate the pace of novel wafer development, we discuss approaches to rapidly evaluate the device efficiency potential of unconventional wafers from injection-dependent lifetime measurements.« less

  3. Evaluation of effect of tray space on the accuracy of condensation silicone, addition silicone and polyether impression materials: an in vitro study.

    PubMed

    Kumar, Varun; Aeran, Himanshu

    2012-09-01

    Optimal thickness of impression materials in the custom tray in order to get the most accurate impression. To investigate the effect of different tray spacer thickness on the accuracy and the dimensional stability of impressions made from monophasic condensation silicone, addition silicone and polyether impression materials. Three different types of elastomeric monophasic impression materials were used for making the impression of a master die with tray having tray spacer thickness of 2, 4 and 6 mm. Each type of impression was poured in die stone after 1 h. Each cast was analyzed by a travelling microscope and compared with the master die. The data was tabulated and subjected to statistical evaluation. The results of the study indicated that the impressions made from 2 to 4 mm spaced trays produced more accurate stone casts when compared to 6 mm spaced tray. No statistical significant differences were observed between the accuracy and dimensional stability of the three materials tested. Minimum changes were observed when the cast was poured after 1 h and the tray space was 2 mm for all the materials tested. It is therefore advisable not to exceed tray space of 2 mm.

  4. Power-law viscous materials for analogue experiments: New data on the rheology of highly-filled silicone polymers

    NASA Astrophysics Data System (ADS)

    Boutelier, D.; Schrank, C.; Cruden, A.

    2008-03-01

    The selection of appropriate analogue materials is a central consideration in the design of realistic physical models. We investigate the rheology of highly-filled silicone polymers in order to find materials with a power-law strain-rate softening rheology suitable for modelling rock deformation by dislocation creep and report the rheological properties of the materials as functions of the filler content. The mixtures exhibit strain-rate softening behaviour but with increasing amounts of filler become strain-dependent. For the strain-independent viscous materials, flow laws are presented while for strain-dependent materials the relative importance of strain and strain rate softening/hardening is reported. If the stress or strain rate is above a threshold value some highly-filled silicone polymers may be considered linear visco-elastic (strain independent) and power-law strain-rate softening. The power-law exponent can be raised from 1 to ˜3 by using mixtures of high-viscosity silicone and plasticine. However, the need for high shear strain rates to obtain the power-law rheology imposes some restrictions on the usage of such materials for geodynamic modelling. Two simple shear experiments are presented that use Newtonian and power-law strain-rate softening materials. The results demonstrate how materials with power-law rheology result in better strain localization in analogue experiments.

  5. Effect of scandium on the optical properties of crystalline silicon material.

    PubMed

    Dong, Xiao; Wang, Yongyong; Li, Xueping; Li, Yingying

    2016-09-01

    We have studied the optical properties of Sc-hyperdoped crystalline silicon based on quantum calculations. We have designed several probable configurations and found that the interstitial atomic positions of Sc (ScI, ScSI, ScTI, ScHI) are stable in the silicon matrix and can largely extend the absorption range of silicon from visible to infrared. The sub-band gap light absorption is attributed to the change of band structures of silicon and its intensity depends on the atomic concentration of Sc in silicon. The special effect of Sc on the properties of silicon will extend the sensitivity of silicon-based photodetectors to near infrared wavelength range.

  6. Effect of scandium on the optical properties of crystalline silicon material.

    PubMed

    Dong, Xiao; Wang, Yongyong; Li, Xueping; Li, Yingying

    2016-09-01

    We have studied the optical properties of Sc-hyperdoped crystalline silicon based on quantum calculations. We have designed several probable configurations and found that the interstitial atomic positions of Sc (ScI, ScSI, ScTI, ScHI) are stable in the silicon matrix and can largely extend the absorption range of silicon from visible to infrared. The sub-band gap light absorption is attributed to the change of band structures of silicon and its intensity depends on the atomic concentration of Sc in silicon. The special effect of Sc on the properties of silicon will extend the sensitivity of silicon-based photodetectors to near infrared wavelength range. PMID:27607729

  7. Influence of pressure and silane depletion on microcrystalline silicon material quality and solar cell performance

    SciTech Connect

    Bugnon, G.; Feltrin, A.; Meillaud, F.; Ballif, C.; Bailat, J.

    2009-03-15

    Hydrogenated microcrystalline silicon growth by very high frequency plasma-enhanced chemical vapor deposition is investigated in an industrial-type parallel plate R and D KAI reactor to study the influence of pressure and silane depletion on material quality. Single junction solar cells with intrinsic layers prepared at high pressures and in high silane depletion conditions exhibit remarkable improvements, reaching 8.2% efficiency. Further analyses show that better cell performances are linked to a significant reduction of the bulk defect density in intrinsic layers. These results can be partly attributed to lower ion bombardment energies due to higher pressures and silane depletion conditions, improving the microcrystalline material quality. Layer amorphization with increasing power density is observed at low pressure and in low silane depletion conditions. A simple model for the average ion energy shows that ion energy estimates are consistent with the amorphization process observed experimentally. Finally, the material quality of a novel regime for high rate deposition is reviewed on the basis of these findings.

  8. Determination of the Wetting Angle of Germanium and Germanium-Silicon Melts on Different Substrate Materials

    NASA Technical Reports Server (NTRS)

    Kaiser, Natalie; Croell, Arne; Szofran, F. R.; Cobb. S. D.; Dold, P.; Benz, K. W.

    1999-01-01

    During Bridgman growth of semiconductors detachment of the crystal and the melt meniscus has occasionally been observed, mainly under microgravity (microg) conditions. An important factor for detached growth is the wetting angle of the melt with the crucible material. High contact angles are more likely to result in detachment of the growing crystal from the ampoule wall. In order to achieve detached growth of germanium (Ge) and germanium-silicon (GeSi) crystals under 1g and microg conditions, sessile drop measurements were performed to determine the most suitable ampoule material as well as temperature dependence of the surface tension for GeSi. Sapphire, fused quartz, glassy carbon, graphite, SiC, pyrolytic Boron Nitride (pBN), AIN, and diamond were used as substrates. Furthermore, different cleaning procedures and surface treatments (etching, sandblasting, etc.) of the same substrate material and their effect on the wetting behavior were studied during these experiments. pBN and AIN substrates exhibited the highest contact angles with values around 170 deg.

  9. Dual-carbon enhanced silicon-based composite as superior anode material for lithium ion batteries

    NASA Astrophysics Data System (ADS)

    Wang, Jie; Liu, Dai-Huo; Wang, Ying-Ying; Hou, Bao-Hua; Zhang, Jing-Ping; Wang, Rong-Shun; Wu, Xing-Long

    2016-03-01

    Dual-carbon enhanced Si-based composite (Si/C/G) has been prepared via employing the widely distributed, low-cost and environmentally friendly Diatomite mineral as silicon raw material. The preparation processes are very simple, non-toxic and easy to scale up. Electrochemical tests as anode material for lithium ion batteries (LIBs) demonstrate that this Si/C/G composite exhibits much improved Li-storage properties in terms of superior high-rate capabilities and excellent cycle stability compared to the pristine Si material as well as both single-carbon modified composites. Specifically for the Si/C/G composite, it can still deliver a high specific capacity of about 470 mAh g-1 at an ultrahigh current density of 5 A g-1, and exhibit a high capacity of 938 mAh g-1 at 0.1 A g-1 with excellent capacity retention in the following 300 cycles. The significantly enhanced Li-storage properties should be attributed to the co-existence of both highly conductive graphite and amorphous carbon in the Si/C/G composite. While the former can enhance the electrical conductivity of the obtained composite, the latter acts as the adhesives to connect the porous Si particulates and conductive graphite flakes to form robust and stable conductive network.

  10. The large shear strain dynamic behaviour of in-vitro porcine brain tissue and a silicone gel model material.

    PubMed

    Brands, D W; Bovendeerd, P H; Peters, G W; Wismans, J S

    2000-11-01

    The large strain dynamic behaviour of brain tissue and silicone gel, a brain substitute material used in mechanical head models, was compared. The non-linear shear strain behaviour was characterised using stress relaxation experiments. Brain tissue showed significant shear softening for strains above 1% (approximately 30% softening for shear strains up to 20%) while the time relaxation behaviour was nearly strain independent. Silicone gel behaved as a linear viscoelastic solid for all strains tested (up to 50%) and frequencies up to 461 Hz. As a result, the large strain time dependent behaviour of both materials could be derived for frequencies up to 1000 Hz from small strain oscillatory experiments and application of Time Temperature Superpositioning. It was concluded that silicone gel material parameters are in the same range as those of brain tissue. Nevertheless the brain tissue response will not be captured exactly due to increased viscous damping at high frequencies and the absence of shear softening in the silicone gel. For trend studies and benchmarking of numerical models the gel can be a good model material.

  11. Visualization of a hyaluronan network on the surface of silicone-hydrogel materials

    PubMed Central

    Wygladacz, Katarzyna A; Hook, Daniel J

    2016-01-01

    Biotrue multipurpose solution (MPS) is a bioinspired disinfecting and conditioning solution that includes hyaluronic acid (HA) as a natural wetting agent. Previous studies demonstrated that HA sorbed from Biotrue MPS on both conventional and silicone hydrogel (SiHy) contact lens materials; an in vitro simulated-wear test validated the presence of HA on the lens surfaces for as long as 20 hours. In this study, the morphology and distribution of HA sorbed from both Biotrue and pure HA solution on SiHy contact lens surfaces was examined. Atomic force microscopy imaging was used to illustrate the topography of fresh SiHy contact lens materials before and after incubation with 0.1% (w/v) HA solution. The distribution, as well as fine details of the HA network, were resolved by first staining HA with Gram’s safranin, then imaging with confocal laser-scanning microscopy and differential interference-contrast microscopy. In this approach, SiHy materials take up the dye (safranin) nonspecifically, such that the resultant safranin–HA complex appears dim against the fluorescent lens background. Balafilcon A was chosen as the representative of glassy SiHy lenses that require postpolymerization plasma treatment to increase wettability. Senofilcon A and samfilcon A were chosen as representatives of SiHy materials fabricated with an internal wetting agent. A confluent and dim HA–safranin network was observed adhered to balafilcon A, senofilcon A, and samfilcon A lens surfaces incubated with either 0.1% (w/v) HA solution or Biotrue MPS. Therefore, the conditioning function provided by Biotrue MPS may be in part explained by the presence of the HA humectant layer that readily sorbs on the various types of SiHy contact lens materials. PMID:27555749

  12. Visualization of a hyaluronan network on the surface of silicone-hydrogel materials.

    PubMed

    Wygladacz, Katarzyna A; Hook, Daniel J

    2016-01-01

    Biotrue multipurpose solution (MPS) is a bioinspired disinfecting and conditioning solution that includes hyaluronic acid (HA) as a natural wetting agent. Previous studies demonstrated that HA sorbed from Biotrue MPS on both conventional and silicone hydrogel (SiHy) contact lens materials; an in vitro simulated-wear test validated the presence of HA on the lens surfaces for as long as 20 hours. In this study, the morphology and distribution of HA sorbed from both Biotrue and pure HA solution on SiHy contact lens surfaces was examined. Atomic force microscopy imaging was used to illustrate the topography of fresh SiHy contact lens materials before and after incubation with 0.1% (w/v) HA solution. The distribution, as well as fine details of the HA network, were resolved by first staining HA with Gram's safranin, then imaging with confocal laser-scanning microscopy and differential interference-contrast microscopy. In this approach, SiHy materials take up the dye (safranin) nonspecifically, such that the resultant safranin-HA complex appears dim against the fluorescent lens background. Balafilcon A was chosen as the representative of glassy SiHy lenses that require postpolymerization plasma treatment to increase wettability. Senofilcon A and samfilcon A were chosen as representatives of SiHy materials fabricated with an internal wetting agent. A confluent and dim HA-safranin network was observed adhered to balafilcon A, senofilcon A, and samfilcon A lens surfaces incubated with either 0.1% (w/v) HA solution or Biotrue MPS. Therefore, the conditioning function provided by Biotrue MPS may be in part explained by the presence of the HA humectant layer that readily sorbs on the various types of SiHy contact lens materials. PMID:27555749

  13. Low cost solar array project. Cell and module formation research area. Process research of non-CZ silicon material

    NASA Astrophysics Data System (ADS)

    1983-02-01

    Liquid diffusion masks and liquid dopants to replace the more expensive CVD SiO2 mask and gaseous diffusion processes were investigated. Silicon pellets were prepared in the silicon shot tower; and solar cells were fabricated using web grown where the pellets were used as a replenishment material. Verification runs were made using the boron dopant and liquid diffusion mask materials. The average of cells produced in these runs was 13%. The relationship of sheet resistivity, temperature, gas flows, and gas composition for the diffusion of the P-8 liquid phosphorus solution was investigated. Solar cells processed from web grown from Si shot material were evaluated, and results qualified the use of the material produced in the shot tower for web furnace feed stock.

  14. Low cost solar array project. Cell and module formation research area. Process research of non-CZ silicon material

    NASA Technical Reports Server (NTRS)

    1983-01-01

    Liquid diffusion masks and liquid dopants to replace the more expensive CVD SiO2 mask and gaseous diffusion processes were investigated. Silicon pellets were prepared in the silicon shot tower; and solar cells were fabricated using web grown where the pellets were used as a replenishment material. Verification runs were made using the boron dopant and liquid diffusion mask materials. The average of cells produced in these runs was 13%. The relationship of sheet resistivity, temperature, gas flows, and gas composition for the diffusion of the P-8 liquid phosphorus solution was investigated. Solar cells processed from web grown from Si shot material were evaluated, and results qualified the use of the material produced in the shot tower for web furnace feed stock.

  15. Investigation of the topographical features of surface carrier concentrations in silicon solar cell material using electrolyte electroreflectance

    NASA Technical Reports Server (NTRS)

    Pollay, F. H.; Okeke, C. E.; Raccah, P. M.

    1977-01-01

    Topographical variations in carrier concentration delta N/N across the surface of n(+) on p diffused silicon solar cell material are studied by utilizing electrolyte electroreflectance with a spatial resolution of 100 microns within approximately 500 A of the surface. The topographical variations of delta N/N approximately 10 - 20% are found to be comparable to Czochralski grown material. The electroreflectance method can also be utilized to investigate other semiconductors such as GaAs.

  16. Synthesis of p-type GaN nanowires.

    PubMed

    Kim, Sung Wook; Park, Youn Ho; Kim, Ilsoo; Park, Tae-Eon; Kwon, Byoung Wook; Choi, Won Kook; Choi, Heon-Jin

    2013-09-21

    GaN has been utilized in optoelectronics for two decades. However, p-type doping still remains crucial for realization of high performance GaN optoelectronics. Though Mg has been used as a p-dopant, its efficiency is low due to the formation of Mg-H complexes and/or structural defects in the course of doping. As a potential alternative p-type dopant, Cu has been recognized as an acceptor impurity for GaN. Herein, we report the fabrication of Cu-doped GaN nanowires (Cu:GaN NWs) and their p-type characteristics. The NWs were grown vertically via a vapor-liquid-solid (VLS) mechanism using a Au/Ni catalyst. Electrical characterization using a nanowire-field effect transistor (NW-FET) showed that the NWs exhibited n-type characteristics. However, with further annealing, the NWs showed p-type characteristics. A homo-junction structure (consisting of annealed Cu:GaN NW/n-type GaN thin film) exhibited p-n junction characteristics. A hybrid organic light emitting diode (OLED) employing the annealed Cu:GaN NWs as a hole injection layer (HIL) also demonstrated current injected luminescence. These results suggest that Cu can be used as a p-type dopant for GaN NWs.

  17. Three-dimensional silicon/carbon core-shell electrode as an anode material for lithium-ion batteries

    NASA Astrophysics Data System (ADS)

    Kim, Jung Sub; Pfleging, Wilhelm; Kohler, Robert; Seifert, Hans Jürgen; Kim, Tae Yong; Byun, Dongjin; Jung, Hun-Gi; Choi, Wonchang; Lee, Joong Kee

    2015-04-01

    Practical application of silicon anodes for lithium-ion batteries has been mainly hindered because of their low electrical conductivity and large volume change (ca. 300%) occurring during the lithiation and delithiation processes. Thus, the surface engineering of active particles (material design) and the modification of electrode structure (electrode design) of silicon are necessary to alleviate these critical limiting factors. Silicon/carbon core-shell particles (Si@C, material design) are prepared by the thermal decomposition and subsequent three-dimensional (3D) electrode structures (electrode design) with a channel width of 15 μm are incorporated using the laser ablation process. The electrochemical characteristics of 3D Si@C used as the anode material for lithium-ion batteries are investigated to identify the effects of material and electrode design. By the introduction of a carbon coating and the laser structuring, an enhanced performance of Si anode materials exhibiting high specific capacity (>1200 mAh g-1 over 300 cycles), good rate capability (1170 mAh g-1 at 8 A g-1), and stable cycling is achieved. The morphology of the core-shell active material combined with 3D channel architecture can minimize the volume expansion by utilizing the void space during the repeated cycling.

  18. Sintered silicon carbide: a new ceramic vessel material for microwave chemistry in single-mode reactors.

    PubMed

    Gutmann, Bernhard; Obermayer, David; Reichart, Benedikt; Prekodravac, Bojana; Irfan, Muhammad; Kremsner, Jennifer M; Kappe, C Oliver

    2010-10-25

    Silicon carbide (SiC) is a strongly microwave absorbing chemically inert ceramic material that can be utilized at extremely high temperatures due to its high melting point and very low thermal expansion coefficient. Microwave irradiation induces a flow of electrons in the semiconducting ceramic that heats the material very efficiently through resistance heating mechanisms. The use of SiC carbide reaction vessels in combination with a single-mode microwave reactor provides an almost complete shielding of the contents inside from the electromagnetic field. Therefore, such experiments do not involve electromagnetic field effects on the chemistry, since the semiconducting ceramic vial effectively prevents microwave irradiation from penetrating the reaction mixture. The involvement of electromagnetic field effects (specific/nonthermal microwave effects) on 21 selected chemical transformations was evaluated by comparing the results obtained in microwave-transparent Pyrex vials with experiments performed in SiC vials at the same reaction temperature. For most of the 21 reactions, the outcome in terms of conversion/purity/product yields using the two different vial types was virtually identical, indicating that the electromagnetic field had no direct influence on the reaction pathway. Due to the high chemical resistance of SiC, reactions involving corrosive reagents can be performed without degradation of the vessel material. Examples include high-temperature fluorine-chlorine exchange reactions using triethylamine trihydrofluoride, and the hydrolysis of nitriles with aqueous potassium hydroxide. The unique combination of high microwave absorptivity, thermal conductivity, and effusivity on the one hand, and excellent temperature, pressure and corrosion resistance on the other hand, makes this material ideal for the fabrication of reaction vessels for use in microwave reactors.

  19. Removal of Silicone Oil From Intraocular Lens Using Novel Surgical Materials

    PubMed Central

    Paschalis, Eleftherios I.; Eliott, Dean; Vavvas, Demetrios G.

    2014-01-01

    Purpose To design, fabricate, and evaluate novel materials to remove silicone oil (SiO) droplets from intraocular lenses (IOL) during vitreoretinal surgery. Methods Three different designs were fabricated using soft lithography of polydimethylsiloxane (PDMS), three-dimensional (3D) inverse PDMS fabrication using water dissolvable particles, and atomic layer deposition (ALD) of alumina (Al2O3) on surgical cellulose fibers. Laboratory tests included static and dynamic contact angle (CA) measurements with water and SiO, nondestructive x-ray microcomputer tomography (micro-CT), and microscopy. SiO removal was performed in vitro and ex vivo using implantable IOLs and explanted porcine eyes. Results All designs exhibited enhanced hydrophobicity and oleophilicity. Static CA measurements with water ranged from 131° to 160° and with SiO CA approximately 0° in 120 seconds following exposure. Nondestructive x-ray analysis of the 3D PDMS showed presence of interconnected polydispersed porosity of 100 to 300 μm in diameter. SiO removal from IOLs was achieved in vitro and ex vivo using standard 20-G vitrectomy instrumentation. Conclusion Removal of SiO from IOLs can be achieved using materials with lower surface energy than that of the IOLs. This can be achieved using appropriate surface chemistry and surface topography. Three designs, with enhanced hydrophobic properties, were fabricated and tested in vitro and ex vivo. All materials remove SiO within an aqueous environment. Preliminary ex vivo results were very promising, opening new possibilities for SiO removal in vitreoretinal surgeries. Translational Relevance This is the first report of an instrument that can lead to successful removal of SiO from the surface of IOL. In addition to the use of this instrument/material in medicine it can also be used in the industry, for example, retrieval of oil spills from bodies of water. PMID:25237593

  20. Effect of silicon and sodium on thermoelectric properties of thallium doped lead telluride based materials

    SciTech Connect

    Zhang, Qinyong; Wang, H; Zhang, Qian; Liu, W.; Yu, Bo; Wang, H; Wang, D.; Ni, G; Chen, Gang; Ren, Z. F.

    2012-01-01

    Thallium (Tl)-doped lead telluride (Tl0.02Pb0.98Te) thermoelectric materials fabricated by ball milling and hot pressing have decent thermoelectric properties but weak mechanical strength. Addition of silicon (Si) nanoparticles strengthened the mechanical property by reducing the grain size and defect density but resulted in low electrical conductivity that was not desired for any thermoelectric materials. Fortunately, doping of sodium (Na) into the Si added Tl0.02Pb0.98Te brings back the high electrical conductivity and yields higher figure-of-merit ZT values of ~1.7 at 770 K. The ZT improvement by Si addition and Na doping in Tl0.02Pb0.98Te sample is the direct result of concurrent electron and phonon engineering by improving the power factor and lowering the thermal conductivity, respectively.

  1. Advanced Non-Destructive Assessment Technology to Determine the Aging of Silicon Containing Materials for Generation IV Nuclear Reactors

    NASA Astrophysics Data System (ADS)

    Koenig, T. W.; Olson, D. L.; Mishra, B.; King, J. C.; Fletcher, J.; Gerstenberger, L.; Lawrence, S.; Martin, A.; Mejia, C.; Meyer, M. K.; Kennedy, R.; Hu, L.; Kohse, G.; Terry, J.

    2011-06-01

    To create an in-situ, real-time method of monitoring neutron damage within a nuclear reactor core, irradiated silicon carbide samples are examined to correlate measurable variations in the material properties with neutron fluence levels experienced by the silicon carbide (SiC) during the irradiation process. The reaction by which phosphorus doping via thermal neutrons occurs in the silicon carbide samples is known to increase electron carrier density. A number of techniques are used to probe the properties of the SiC, including ultrasonic and Hall coefficient measurements, as well as high frequency impedance analysis. Gamma spectroscopy is also used to examine residual radioactivity resulting from irradiation activation of elements in the samples. Hall coefficient measurements produce the expected trend of increasing carrier concentration with higher fluence levels, while high frequency impedance analysis shows an increase in sample impedance with increasing fluence.

  2. Phosphorous and aluminum gettering in Silicon-Film{trademark} Product II material

    SciTech Connect

    Cotter, J.E.; Barnett, A.M.; Hall, R.B.

    1995-08-01

    Gettering processes are being developed for the Silicon-Film{trademark} Product II solar cell structure. These processes have been developed specifically for films of silicon grown on dissimilar substrates with barrier layers. Gettering with both phosphorous- and aluminum-based processing sequences has resulted in enhancement of minority carrier diffusion length. Long diffusion lengths have allowed the characterization of light trapping in thin films of silicon grown on barrier-coated substrates.

  3. Study program to develop and evaluate die and container materials for the growth of silicon ribbons. [for development of low cost solar cells

    NASA Technical Reports Server (NTRS)

    Addington, L. A.; Ownby, P. D.; Yu, B. B.; Barsoum, M. W.; Romero, H. V.; Zealer, B. G.

    1979-01-01

    The development and evaluation of proprietary coatings of pure silicon carbide, silicon nitride, and aluminum nitride on less pure hot pressed substrates of the respective ceramic materials, is described. Silicon sessile drop experiments were performed on coated test specimens under controlled oxygen partial pressure. Prior to testing, X-ray diffraction and SEM characterization was performed. The reaction interfaces were characterized after testing with optical and scanning electron microscopy and Auger electron spectroscopy. Increasing the oxygen partial pressure was found to increase the molten silicon contact angle, apparently because adsorbed oxygen lowers the solid-vapor interfacial free energy. It was also found that adsorbed oxygen increased the degree of attack of molten silicon upon the chemical vapor deposited coatings. Cost projections show that reasonably priced, coated, molten silicon resistant refractory material shapes are obtainable.

  4. Performances of miniature microstrip detectors made on oxygen enriched p-type substrates after very high proton irradiation

    NASA Astrophysics Data System (ADS)

    Casse, G.; Allport, P. P.; Martí i Garcia, S.; Lozano, M.; Turner, P. R.

    2004-12-01

    Silicon microstrip detectors with n-type implant read-out strips on FZ p-type bulk (n-in-p) show superior charge collection properties, after heavy irradiation, to the more standard p-strips in n-type silicon (p-in-n). It is also well established that oxygen-enriched n-type silicon substrates show better performance, in terms of degradation of the full depletion voltage after charged hadron irradiation, than the standard FZ silicon used for high energy physics detectors. Silicon microstrip detectors combining both the advantages of oxygenation and of n-strip read-out (n-in-n) have achieved high radiation tolerance to charged hadrons. The manufacturing of n-in-n detectors though requires double-sided processing, resulting in more complicated and expensive devices than standard p-in-n. A cheaper single-sided option, that still combines these advantages, is to use n-in-p devices. P-type FZ wafers have been oxygen-enriched by high temperature diffusion from an oxide layer and succesfully used to process miniature (1×1 cm 2) microstrip detectors. These detectors have been irradiated with 24 GeV/c protons in the CERN/PS T7 irradiation area up to ˜7.5×10 15 cm -2. We report results with these irradiated detectors in terms of the charge collection efficiency as a function of the applied bias voltage.

  5. Study of the effects of impurities on the properties of silicon materials and performance of silicon solar cell

    NASA Technical Reports Server (NTRS)

    Sah, C. T.

    1981-01-01

    The effect of silicon film thickness on the energy conversion efficiency of a back surface field solar cell is investigated. A computer-aided design study on the dependence of efficiency peaks on the concentrations of the recombination and dopant impurities is presented. The illuminated current voltage characteristics of over 100 cell designs were obtained using the transmission line circuit model to numerically solve the Shockley Equations. Using an AM1 efficiency of 17% as a target value, it is shown that the efficiency versus thickness dependence has a broad maximum which varies less than 1% over more than three-to-one range of cell thickness from 30 to 100 microns. Optical reflecting back surface will give only a slight improvement of AM1 efficiency, about 0.7%, in this thickness range. The sensitive dependence of efficiency on patchiness across the back surface field, low high junction in thin cells is noted.

  6. Fast characterization of functionalized silica materials by silicon-29 surface-enhanced NMR spectroscopy using dynamic nuclear polarization.

    PubMed

    Lelli, Moreno; Gajan, David; Lesage, Anne; Caporini, Marc A; Vitzthum, Veronika; Miéville, Pascal; Héroguel, Florent; Rascón, Fernando; Roussey, Arthur; Thieuleux, Chloé; Boualleg, Malika; Veyre, Laurent; Bodenhausen, Geoffrey; Copéret, Christophe; Emsley, Lyndon

    2011-02-23

    We demonstrate fast characterization of the distribution of surface bonding modes and interactions in a series of functionalized materials via surface-enhanced nuclear magnetic resonance spectroscopy using dynamic nuclear polarization (DNP). Surface-enhanced silicon-29 DNP NMR spectra were obtained by using incipient wetness impregnation of the sample with a solution containing a polarizing radical (TOTAPOL). We identify and compare the bonding topology of functional groups in materials obtained via a sol-gel process and in materials prepared by post-grafting reactions. Furthermore, the remarkable gain in time provided by surface-enhanced silicon-29 DNP NMR spectroscopy (typically on the order of a factor 400) allows the facile acquisition of two-dimensional correlation spectra. PMID:21280606

  7. Evaluation of effectiveness of microwave irradiation for disinfection of silicone elastomeric impression material.

    PubMed

    Bhasin, Abhilasha; Vinod, V; Bhasin, Vinny; Mathew, Xavier; Sajjan, Suresh; Ahmed, Syed Tauqheer

    2013-06-01

    Use of domestic microwave oven has been suggested as a method of disinfecting a number of dental materials used in dental practice. This study was done to analyse the effect of microwave irradiation on vinyl polysiloxane putty impression material (3M ESPE, Express™ STD) contaminated with test organisms (Staphylococcus aureus, Pseudomonas aeruginosa, Candida albicans. 180 square shaped specimens of addition silicon putty material were prepared and divided into 3 groups for three test organisms. The 3 groups were subdivided into 4 subgroups (n = 15) for different exposure parameters (control group 5, 6 and 7 min exposure at 650 W. The specimens were contaminated using standard inoculums of test organism and then were irradiated using domestic microwaves. Broth cultures of the control and test group specimens were plated on selective media culture plates. Colonies formed were counted. Data analyses included Kruskal-Walli's ANOVA and Mann-Whitney's tests. Nil values shows complete elimination of C. albicans and P. aeruginosa after 5, 6 and 7 min exposure. Staphylococcus aureus showed colonies with the mean value of 7.6 × 10(3) ± 2.3 × 10(3), 4.6 × 10(3) ± 2.6 × 10(3) after 5 and 6 min respectively and nil values after 7 min exposure. 5 min exposure caused complete elimination of C. albicans and P. aeruginosa strains, while 7 min exposure eliminated S. aureus completely.

  8. A nitrogen-hyperdoped silicon material formed by femtosecond laser irradiation

    SciTech Connect

    Dong, Xiao; Zhu, Zhen; Shao, Hezhu; Rong, Ximing; Zhuang, Jun; Li, Ning; Liang, Cong; Sun, Haibin; Zhao, Li; Feng, Guojin

    2014-03-03

    A supersaturation of nitrogen atoms is found in the surface layer of microstructured silicon after femtosecond (fs) laser irradiation in NF{sub 3}. The average nitrogen concentration in the uppermost 50 nm is about 0.5 ± 0.2 at. %, several orders of magnitude higher than the solid solubility of nitrogen atoms in silicon. The nitrogen-hyperdoped silicon shows high crystallinity in the doped layer, which is due to the repairing effect of nitrogen on defects in silicon lattices. Nitrogen atoms and vacancies can be combined into thermal stable complexes after fs laser irradiation, which makes the nitrogen-hyperdoped silicon exhibit good thermal stability of optical properties.

  9. Low-cost solar array project task 1: Silicon material. Gaseous melt replenishment system

    NASA Technical Reports Server (NTRS)

    Jewett, D. N.; Bates, H. E.; Hill, D. M.

    1980-01-01

    The operation of a silicon production technique was demonstrated. The essentials of the method comprise chemical vapor deposition of silicon, by hydrogen reduction of chlorosilanes, on the inside of a quartz reaction vessel having large internal surface area. The system was designed to allow successive deposition-melting cycles, with silicon removal being accomplished by discharging the molten silicon. The liquid product would be suitable for transfer to a crystal growth process, casting into solid form, or production of shots. A scaled-down prototype reactor demonstrated single pass conversion efficiency of 20 percent and deposition rates and energy consumption better than conventional Siemens reactors, via deposition rates of 365 microns/hr. and electrical consumption of 35 Kwhr/kg of silicon produced.

  10. p-type conduction in sputtered indium oxide films

    SciTech Connect

    Stankiewicz, Jolanta; Alcala, Rafael; Villuendas, Francisco

    2010-05-10

    We report p-type conductivity in intrinsic indium oxide (IO) films deposited by magnetron sputtering on fused quartz substrates under oxygen-rich ambient. Highly oriented (111) films were studied by x-ray diffraction, optical absorption, and Hall effect measurements. We fabricated p-n homojunctions on these films.

  11. High carrier concentration p-type transparent conducting oxide films

    DOEpatents

    Yan, Yanfa; Zhang, Shengbai

    2005-06-21

    A p-type transparent conducting oxide film is provided which is consisting essentially of, the transparent conducting oxide and a molecular doping source, the oxide and doping source grown under conditions sufficient to deliver the doping source intact onto the oxide.

  12. Synthesis of p-type GaN nanowires

    NASA Astrophysics Data System (ADS)

    Kim, Sung Wook; Park, Youn Ho; Kim, Ilsoo; Park, Tae-Eon; Kwon, Byoung Wook; Choi, Won Kook; Choi, Heon-Jin

    2013-08-01

    GaN has been utilized in optoelectronics for two decades. However, p-type doping still remains crucial for realization of high performance GaN optoelectronics. Though Mg has been used as a p-dopant, its efficiency is low due to the formation of Mg-H complexes and/or structural defects in the course of doping. As a potential alternative p-type dopant, Cu has been recognized as an acceptor impurity for GaN. Herein, we report the fabrication of Cu-doped GaN nanowires (Cu:GaN NWs) and their p-type characteristics. The NWs were grown vertically via a vapor-liquid-solid (VLS) mechanism using a Au/Ni catalyst. Electrical characterization using a nanowire-field effect transistor (NW-FET) showed that the NWs exhibited n-type characteristics. However, with further annealing, the NWs showed p-type characteristics. A homo-junction structure (consisting of annealed Cu:GaN NW/n-type GaN thin film) exhibited p-n junction characteristics. A hybrid organic light emitting diode (OLED) employing the annealed Cu:GaN NWs as a hole injection layer (HIL) also demonstrated current injected luminescence. These results suggest that Cu can be used as a p-type dopant for GaN NWs.GaN has been utilized in optoelectronics for two decades. However, p-type doping still remains crucial for realization of high performance GaN optoelectronics. Though Mg has been used as a p-dopant, its efficiency is low due to the formation of Mg-H complexes and/or structural defects in the course of doping. As a potential alternative p-type dopant, Cu has been recognized as an acceptor impurity for GaN. Herein, we report the fabrication of Cu-doped GaN nanowires (Cu:GaN NWs) and their p-type characteristics. The NWs were grown vertically via a vapor-liquid-solid (VLS) mechanism using a Au/Ni catalyst. Electrical characterization using a nanowire-field effect transistor (NW-FET) showed that the NWs exhibited n-type characteristics. However, with further annealing, the NWs showed p-type characteristics. A homo

  13. Tuning oxygen impurities and microstructure of nanocrystalline silicon photovoltaic materials through hydrogen dilution

    PubMed Central

    2014-01-01

    As a great promising material for third-generation thin-film photovoltaic cells, hydrogenated nanocrystalline silicon (nc-Si:H) thin films have a complex mixed-phase structure, which determines its defectful nature and easy residing of oxygen impurities. We have performed a detailed investigation on the microstructure properties and oxygen impurities in the nc-Si:H thin films prepared under different hydrogen dilution ratio treatment by the plasma-enhanced chemical vapor deposition (PECVD) process. X-ray diffraction, transmission electron microscopy, Raman spectroscopy, and optical transmission spectroscopy have been utilized to fully characterize the microstructure properties of the nc-Si:H films. The oxygen and hydrogen contents have been obtained from infrared absorption spectroscopy. And the configuration state of oxygen impurities on the surface of the films has been confirmed by X-ray photoelectron spectroscopy, indicating that the films were well oxidized in the form of SiO2. The correlation between the hydrogen content and the volume fraction of grain boundaries derived from the Raman measurements shows that the majority of the incorporated hydrogen is localized inside the grain boundaries. Furthermore, with the detailed information on the bonding configurations acquired from the infrared absorption spectroscopy, a full explanation has been provided for the mechanism of the varying microstructure evolution and oxygen impurities based on the two models of ion bombardment effect and hydrogen-induced annealing effect. PMID:24994958

  14. Monodisperse porous silicon spheres as anode materials for lithium ion batteries.

    PubMed

    Wang, Wei; Favors, Zachary; Ionescu, Robert; Ye, Rachel; Bay, Hamed Hosseini; Ozkan, Mihrimah; Ozkan, Cengiz S

    2015-03-05

    Highly monodisperse porous silicon nanospheres (MPSSs) are synthesized via a simple and scalable hydrolysis process with subsequent surface-protected magnesiothermic reduction. The spherical nature of the MPSSs allows for a homogenous stress-strain distribution within the structure during lithiation and delithiation, which dramatically improves the electrochemical stability. To fully extract the real performance of the MPSSs, carbon nanotubes (CNTs) were added to enhance the electronic conductivity within the composite electrode structure, which has been verified to be an effective way to improve the rate and cycling performance of anodes based on nano-Si. The Li-ion battery (LIB) anodes based on MPSSs demonstrate a high reversible capacity of 3105 mAh g(-1). In particular, reversible Li storage capacities above 1500 mAh g(-1) were maintained after 500 cycles at a high rate of C/2. We believe this innovative approach for synthesizing porous Si-based LIB anode materials by using surface-protected magnesiothermic reduction can be readily applied to other types of SiOx nano/microstructures.

  15. Fabrication of Silicon Nitride Dental Core Ceramics with Borosilicate Veneering material

    NASA Astrophysics Data System (ADS)

    Wananuruksawong, R.; Jinawath, S.; Padipatvuthikul, P.; Wasanapiarnpong, T.

    2011-10-01

    Silicon nitride (Si3N4) ceramic is a great candidate for clinical applications due to its high fracture toughness, strength, hardness and bio-inertness. This study has focused on the Si3N4 ceramic as a dental core material. The white Si3N4 was prepared by pressureless sintering at relative low sintering temperature of 1650 °C in nitrogen atmosphere. The coefficient of thermal expansion (CTE) of Si3N4 ceramic is lower than that of Zirconia and Alumina ceramic which are popular in this field. The borosilicate glass veneering was employed due to its compatibility in thermal expansion. The sintered Si3N4 specimens represented the synthetic dental core were paintbrush coated by a veneer paste composed of borosilicate glass powder (<150 micrometer, Pyrex) with 5 wt% of zirconia powder (3 wt% Y2O3 - partial stabilized zirconia) and 30 wt% of polyvinyl alcohol (5 wt% solution). After coating the veneer on the Si3N4 specimens, the firing was performed in electric tube furnace between 1000-1200°C. The veneered specimens fired at 1100°C for 15 mins show good bonding, smooth and glossy without defect and crazing. The veneer has thermal expansion coefficient as 3.98×10-6 °C-1, rather white and semi opaque, due to zirconia addition, the Vickers hardness as 4.0 GPa which is closely to the human teeth.

  16. Alkaline and ultrasonic dissolution of biological materials for trace silicon determination

    PubMed Central

    Viveros, Robert D.; Liberman, Alexander; Trogler, William C.; Kummel, Andrew C.

    2015-01-01

    A simple method for trace elemental determination in biological tissue has been developed. Novel nanomaterials with biomedical applications necessitate the determination of the in vivo fate of the materials to understand their toxicological profile. Hollow iron-doped calcined silica nanoshells have been used as a model to demonstrate that potassium hydroxide and bath sonication at 50 °C can extract elements from alkaline-soluble nanomaterials. After alkali digestion, nitric acid is used to adjust the pH into a suitable range for analysis using techniques such as inductively coupled plasma optical emission spectrometry which require neutral or acidic analytes. In chicken liver phantoms injected with the nanoshells, 96% of the expected silicon concentration was detected. This value was in good agreement with the 94% detection efficiency of nanoshells dissolved in aqueous solution as a control for potential sample matrix interference. Nanoshell detection was further confirmed in a mouse 24 h after intravenous administration; the measured silica above baseline was 35 times greater or more than the standard deviations of the measurements. This method provides a simple and accurate means to quantify alkaline-soluble nanomaterials in biological tissue. PMID:25909037

  17. Oxygen-doped porous silicon carbide spheres as electrode materials for supercapacitors.

    PubMed

    Kim, Myeongjin; Ju, Hyun; Kim, Jooheon

    2016-01-28

    Oxygen-containing functional groups were introduced onto the surface of the micro- and meso-porous silicon carbide sphere (MMPSiC) in order to investigate the relationship between the electric double layer properties and pseudo-capacitive properties; the degree of oxidation of MMPSiC was also optimized. Although the oxygenated surface functionalities can lead to a decrease in the surface area of MMPSiC, the oxygen functional groups attached to the external surface can participate in the redox reaction, resulting in the enhancement of the total super-capacitive performance. The MMPSiC electrode oxidized for 24 h exhibits a high charge storage capacity with a specific capacitance of 301.1 F g(-1) at a scan rate of 5 mV s(-1), with 86.8% rate performance from 5 to 500 mV s(-1) in 1 M KCl aqueous electrolyte. This outstanding capacitive performance of the MMPSiC electrode oxidized for 24 h can be attributed to the harmonious synergistic effect between the electric double layer capacitive contribution of MMPSiC and the pseudo-capacitive contribution of the oxygen-containing functional groups. These encouraging results demonstrate that the MMPSiC electrode oxidized for 24 h is a promising candidate for high performance electrode materials for supercapacitors. PMID:26752728

  18. Monodisperse Porous Silicon Spheres as Anode Materials for Lithium Ion Batteries

    NASA Astrophysics Data System (ADS)

    Wang, Wei; Favors, Zachary; Ionescu, Robert; Ye, Rachel; Bay, Hamed Hosseini; Ozkan, Mihrimah; Ozkan, Cengiz S.

    2015-03-01

    Highly monodisperse porous silicon nanospheres (MPSSs) are synthesized via a simple and scalable hydrolysis process with subsequent surface-protected magnesiothermic reduction. The spherical nature of the MPSSs allows for a homogenous stress-strain distribution within the structure during lithiation and delithiation, which dramatically improves the electrochemical stability. To fully extract the real performance of the MPSSs, carbon nanotubes (CNTs) were added to enhance the electronic conductivity within the composite electrode structure, which has been verified to be an effective way to improve the rate and cycling performance of anodes based on nano-Si. The Li-ion battery (LIB) anodes based on MPSSs demonstrate a high reversible capacity of 3105 mAh g-1. In particular, reversible Li storage capacities above 1500 mAh g-1 were maintained after 500 cycles at a high rate of C/2. We believe this innovative approach for synthesizing porous Si-based LIB anode materials by using surface-protected magnesiothermic reduction can be readily applied to other types of SiOx nano/microstructures.

  19. Monodisperse Porous Silicon Spheres as Anode Materials for Lithium Ion Batteries

    PubMed Central

    Wang, Wei; Favors, Zachary; Ionescu, Robert; Ye, Rachel; Bay, Hamed Hosseini; Ozkan, Mihrimah; Ozkan, Cengiz S.

    2015-01-01

    Highly monodisperse porous silicon nanospheres (MPSSs) are synthesized via a simple and scalable hydrolysis process with subsequent surface-protected magnesiothermic reduction. The spherical nature of the MPSSs allows for a homogenous stress-strain distribution within the structure during lithiation and delithiation, which dramatically improves the electrochemical stability. To fully extract the real performance of the MPSSs, carbon nanotubes (CNTs) were added to enhance the electronic conductivity within the composite electrode structure, which has been verified to be an effective way to improve the rate and cycling performance of anodes based on nano-Si. The Li-ion battery (LIB) anodes based on MPSSs demonstrate a high reversible capacity of 3105 mAh g−1. In particular, reversible Li storage capacities above 1500 mAh g−1 were maintained after 500 cycles at a high rate of C/2. We believe this innovative approach for synthesizing porous Si-based LIB anode materials by using surface-protected magnesiothermic reduction can be readily applied to other types of SiOx nano/microstructures. PMID:25740298

  20. FABRICATION OF A RETINAL PROSTHETIC TEST DEVICE USING ELECTRODEPOSITED SILICON OVER POLYPYRROLE PATTERNED WITH SU-8 PHOTORESIST

    PubMed Central

    Miller, Eric; Ellis, Daniel; Charles, Duran; McKenzie, Jason

    2016-01-01

    A materials fabrication study of a photodiode array for possible application of retina prosthesis was undertaken. A test device was fabricated using a glassy carbon electrode patterned with SU-8 photoresist. In the openings, p-type polypyrrole was first electrodeposited using 1-butyl-1-methylpyridinium bis(trifluoromethylsulfonyl)imide ionic liquid. The polypyrrole was self-doped with imide ion at ~1.5 mole %, was verified as p-type, and had a resistivity of ~20 Ωcm. N-type Silicon was then electrodeposited over this layer using silicon tetrachloride / phosphorus trichloride in acetonitrile and passivated in a second electrodeposition using trimethylchlorosilane. Electron microscopy revealed the successful electrodeposition of silicon over patterned polypyrrole. Rudimentary photodiode behavior was observed. The passivation improved but did not completely protect the electrodeposited silicon from oxidation by air. PMID:27616940

  1. FABRICATION OF A RETINAL PROSTHETIC TEST DEVICE USING ELECTRODEPOSITED SILICON OVER POLYPYRROLE PATTERNED WITH SU-8 PHOTORESIST

    PubMed Central

    Miller, Eric; Ellis, Daniel; Charles, Duran; McKenzie, Jason

    2016-01-01

    A materials fabrication study of a photodiode array for possible application of retina prosthesis was undertaken. A test device was fabricated using a glassy carbon electrode patterned with SU-8 photoresist. In the openings, p-type polypyrrole was first electrodeposited using 1-butyl-1-methylpyridinium bis(trifluoromethylsulfonyl)imide ionic liquid. The polypyrrole was self-doped with imide ion at ~1.5 mole %, was verified as p-type, and had a resistivity of ~20 Ωcm. N-type Silicon was then electrodeposited over this layer using silicon tetrachloride / phosphorus trichloride in acetonitrile and passivated in a second electrodeposition using trimethylchlorosilane. Electron microscopy revealed the successful electrodeposition of silicon over patterned polypyrrole. Rudimentary photodiode behavior was observed. The passivation improved but did not completely protect the electrodeposited silicon from oxidation by air.

  2. [Studies on the cytotoxic action of various silicone rubber impression materials by means of cell culture (author's transl)].

    PubMed

    Watanabe, H

    1977-07-01

    Biological test of the silicone rubber impression materials was done by utilizing tissue cultures of L strain cells. Criteria for cytotoxicity were based upon response index in agar diffusion method which was determined by zone index and lysis index, and morphological observations of the cells. The materials used were chosen among those which were commercially available. Base material, catalyst, unset and set mixes of both materials were tested respectively. X-ray fluorescence analysis of the material was also performed. Following results were obtained. 1) Base material of all the materials showed zone index of a range between 11.8 mm and 18.6 mm. On the otherhand, lysis index was relatively small and minimum response index was 11.8 mm/8.6 mm. The cells appeared normal after cultivation with the base materials, though tissue culture medium became opaque due to dissolution of the base materials. It is revealed that the above results mean little cytotoxicity to the cells. 2) Catalyst, on the otherhand, yielded intense cytotoxicity. Minimum response index for the catalyst was 13.4 mm/14.8 mm. Morphological observation was parallel to the results of agar diffusion method. 3) Unset mixes also yielded intense to moderate cytotoxicity. 4) Set mixes showed a similar in level of cytotoxicity to the unset mixes. 5) X-ray fluorescence analysis of the materials revealed existence of such elements as Si, Sr, Sn, S, Cu and Fe. Moreover, Zn was found in materials A, B, C, D and E; P in materials A and B, and Pb in materials E and F. However, it was unable to show what compound was formed by these elements. It is expected that the present results could give a clue on animal experiments or clinical use from the view point of biocompatibility of silicone rubber impression materials. PMID:282367

  3. Solid Silicone Elastomer Material(DC745U)-Historical Overview and New Experimental Results

    SciTech Connect

    Ortiz-Acosta, Denisse

    2012-08-08

    DC745U is a silicone elastomer used in several weapon systems. DC745U is manufactured by Dow Corning and its formulation is proprietary. Risk changes without notification to the customer. {sup 1}H and {sup 29}Si{l_brace}{sup 1}H{r_brace} NMR have previously determined that DC745U contains {approx} 98.5% dimethyl siloxane, {approx}1.5% methyl-phenyl siloxane, and a small amount (<1%) of vinyl siloxane repeat units that are converted to crosslinking sites. The polymer is filled with {approx} 38 wt.% of a mixture of fumed silica and quartz. Some conclusions are: (1) DMA shows that crystallization does have an effect on the mechanical properties of DC745U; (2) DMA shows that the crystallization is time and temperature dependent; (3) Mechanical tests show that DC745U undergo a crystalline transition at temperatures below -50 C; (4) Rate and temperature does not have an effect above crystalline transition; (5) Crystalline transition occurs faster at colder temperatures; (6) The material remains responsive and recovers after warming it to temperature above -40 C; (7) We were able to review all previous historical data on DC745U; (8) Identified specific gaps in materials understanding; (9) Developed design of experiments and testing methods to address gaps associated with post-curing and low temperature mechanical behavior; (10) Resolved questions of post-cure and alleviated concerns associated with low temperature mechanical behavior with soak time and temperature; and (11) This work is relevant to mission-critical programs and for supporting programmatic work for weapon research.

  4. Corrosion Processes of the CANDU Steam Generator Materials in the Presence of Silicon Compounds

    SciTech Connect

    Lucan, Dumitra; Fulger, Manuela; Velciu, Lucian; Lucan, Georgiana; Jinescu, Gheorghita

    2006-07-01

    The feedwater that enters the steam generators (SG) under normal operating conditions is extremely pure but, however, it contains low levels (generally in the {mu}g/l concentration range) of impurities such as iron, chloride, sulphate, silicate, etc. When water is converted into steam and exits the steam generator, the non-volatile impurities are left behind. As a result of their concentration, the bulk steam generator water is considerably higher than the one in the feedwater. Nevertheless, the concentrations of corrosive impurities are in general sufficiently low so that the bulk water is not significantly aggressive towards steam generator materials. The impurities and corrosion products existing in the steam generator concentrate in the porous deposits on the steam generator tubesheet. The chemical reactions that take place between the components of concentrated solutions generate an aggressive environment. The presence of this environment and of the tubesheet crevices lead to localized corrosion and thus the same tubes cannot ensure the heat transfer between the fluids of the primary and secondary circuits. Thus, it becomes necessary the understanding of the corrosion process that develops into SG secondary side. The purpose of this paper is the assessment of corrosion behavior of the tubes materials (Incoloy-800) at the normal secondary circuit parameters (temperature = 2600 deg C, pressure = 5.1 MPa). The testing environment was demineralized water containing silicon compounds, at a pH=9.5 regulated with morpholine and cyclohexyl-amine (all volatile treatment - AVT). The paper presents the results of metallographic examinations as well as the results of electrochemical measurements. (authors)

  5. Investigation of Intrinsic Electrical Characteristics and Contact Effects in p-Type Tin Monoxide Thin-Film Transistors Using Gated-Four-Probe Measurements.

    PubMed

    Han, Young-Joon; Choi, Yong-Jin; Jeong, Hoon; Kwon, Hyuck-In

    2015-10-01

    We investigate the intrinsic electrical characteristics and source/drain parasitic resistance in p-type SnO TFTs fabricated using Ni electrodes based on the gated-four-probe method. Because of the relatively high work function and inexpensive price, Ni has been most frequently used as the source/drain electrode materials in p-type SnO TFTs. However, our experimental data shows that the width normalized parasitic resistances of SnO TFT with Ni electrodes are around one to three orders of magnitude higher than those in the representative n-type oxide TFT, amorphous indium- gallium-zinc oxide TFT, and are comparable with those in amorphous silicon TFTs with Mo electrodes. This result implies that the electrical performance of the short channel SnO TFT can be dominated by the source/drain parasitic resistances. The intrinsic field-effect mobility extracted without being influenced by source/drain parasitic resistance was ~2.0 cm2/Vs, which is around twice the extrinsic field-effect mobility obtained from the conventional transconductance method. The large contact resistance is believed to be mainly caused from the heterogeneous electronic energy-level mismatch between the SnO and Ni electrodes. PMID:26726376

  6. Highly sensitive wide bandwidth photodetector based on internal photoemission in CVD grown p-type MoS2/graphene Schottky junction.

    PubMed

    Vabbina, PhaniKiran; Choudhary, Nitin; Chowdhury, Al-Amin; Sinha, Raju; Karabiyik, Mustafa; Das, Santanu; Choi, Wonbong; Pala, Nezih

    2015-07-22

    Two dimensional (2D) Molybdenum disulfide (MoS2) has evolved as a promising material for next generation optoelectronic devices owing to its unique electrical and optical properties, such as band gap modulation, high optical absorption, and increased luminescence quantum yield. The 2D MoS2 photodetectors reported in the literature have presented low responsivity compared to silicon based photodetectors. In this study, we assembled atomically thin p-type MoS2 with graphene to form a MoS2/graphene Schottky photodetector where photo generated holes travel from graphene to MoS2 over the Schottky barrier under illumination. We found that the p-type MoS2 forms a Schottky junction with graphene with a barrier height of 139 meV, which results in high photocurrent and wide spectral range of detection with wavelength selectivity. The fabricated photodetector showed excellent photosensitivity with a maximum photo responsivity of 1.26 AW(-1) and a noise equivalent power of 7.8 × 10(-12) W/√Hz at 1440 nm.

  7. Mechanisms for p -type behavior of ZnO, Zn1 -xMgxO , and related oxide semiconductors

    NASA Astrophysics Data System (ADS)

    Urban, Daniel F.; Körner, Wolfgang; Elsässer, Christian

    2016-08-01

    The possibilities of turning intrinsically n -type oxide semiconductors like ZnO and Zn1 -xMgxO into p -type materials are investigated. Motivated by recent experiments on Zn1 -xMgxO doped with nitrogen, we analyze the electronic defect levels of point defects NO,vZn, and NO-vZn pairs in ZnO and Zn1 -xMgxO by means of self-interaction-corrected density functional theory calculations. We show how the interplay of defects can lead to shallow acceptor defect levels, although the levels of individual point defects NO are too deep in the band gap to be responsible for p -type conduction. We relate our results to p -type conduction paths at grain boundaries seen in polycrystalline ZnO and develop an understanding of a p -type mechanism which is common to ZnO, Zn1 -xMgxO , and related materials.

  8. Influence of Containment on the Growth of Silicon-Germanium: A Materials Science Flight Project

    NASA Technical Reports Server (NTRS)

    Volz, M. P.; Mazuruk, K.; Croell, A.

    2012-01-01

    This investigation involves the comparison of results achieved from three types of crystal growth of germanium and germanium-silicon alloys: (1) Float zone growth (2) Bridgman growth (3) Detached Bridgman growth crystal The fundamental goal of the proposed research is to determine the influence of containment on the processing-induced defects and impurity incorporation in germanium-silicon (GeSi) crystals (silicon concentration in the solid up to 5 at%) for three different growth configurations in order to quantitatively assess the improvements of crystal quality possible by detached growth.

  9. Mechanic and surface properties of central-venous port catheters after removal: A comparison of polyurethane and silicon rubber materials.

    PubMed

    Braun, Ulrike; Lorenz, Edelgard; Weimann, Christiane; Sturm, Heinz; Karimov, Ilham; Ettl, Johannes; Meier, Reinhard; Wohlgemuth, Walter A; Berger, Hermann; Wildgruber, Moritz

    2016-12-01

    Central venous port devices made of two different polymeric materials, thermoplastic polyurethane (TPU) and silicone rubber (SiR), were compared due their material properties. Both naïve catheters as well as catheters after removal from patients were investigated. In lab experiments the influence of various chemo-therapeutic solutions on material properties was investigated, whereas the samples after removal were compared according to the implanted time in patient. The macroscopic, mechanical performance was assessed with dynamic, specially adapted tests for elasticity. The degradation status of the materials was determined with common tools of polymer characterisation, such as infrared spectroscopy, molecular weight measurements and various methods of thermal analysis. The surface morphology was analysed using scanning electron microscopy. A correlation between material properties and clinical performance was proposed. The surface morphology and chemical composition of the polyurethane catheter materials can potentially result in increased susceptibility of the catheter to bloodstream infections and thrombotic complications. The higher mechanic failure, especially with increasing implantation time of the silicone catheters is related to the lower mechanical performance compared to the polyurethane material as well as loss of barium sulphate filler particles near the surface of the catheter. This results in preformed microscopic notches, which act as predetermined sites of fracture. PMID:27552159

  10. Computational design of p-type contacts for MoS2-based electronic devices

    NASA Astrophysics Data System (ADS)

    Kumar, Priyank; Musso, Tiziana; Foster, Adam; Grossman, Jeffrey

    2015-03-01

    The excellent physical and semiconducting properties of transition metal dichalcogenide (TMDC) monolayers make them promising materials for many applications. A well-known example is MoS2, which has gained significant attention as a channel material for next-generation transistors. While n-type MoS2 field-effect transistors (n-FETs) can be fabricated with relative ease, fabrication of p-FETs remains a challenge as the Fermi-level of elemental metals used as contacts are pinned close to the conduction band, leading to large p-type Schottky barrier heights (SBHs). Using ab initio computations, we design and propose efficient hole contacts utilizing high work function oxide-based hole injection materials, with the aim of advancing p-type MoS2 device technology. Our calculations will highlight the possibility to tune and lower the p-type SBH at the metal/semiconductor interface by controlling the structural properties of oxide materials. Taken together, our results provide an interesting platform for experimental design of next-generation MoS2-based electronic and optoelectronic devices.

  11. A direct solid sampling electrothermal atomic absorption spectrometry method for the determination of silicon in biological materials

    NASA Astrophysics Data System (ADS)

    Huang, M. D.; Krivan, V.

    2007-03-01

    A solid sampling electrothermal atomic absorption spectrometry method for direct determination of trace silicon in biological materials was developed and applied to analysis of pork liver, bovine liver SRM 1577b and pure cellulose. The organic matrix was destroyed and expelled from the furnace in the pyrolysis stage involving a step-wise increasing the temperature from 160 °C to 1200 °C. The mixed Pd/Mg(NO 3) 2 modifier has proved to be the optimum one with respect to the achievement of maximum sensitivity, elimination of the effect of the remaining inorganic substances and the possibility of using calibration curves measured with aqueous standard solutions for quantification. For the maximum applicable sample amount of 6 mg, the limit of detection was found to be 30 ng g - 1 . The results were compared with those obtained by different spectrometric methods involving sample digestion, by electrothermal atomic absorption spectrometry using slurry sampling, by wavelength dispersive X-ray fluorescence spectrometry and by radiochemical neutron activation analysis. The method seems to be a promising one for analysis of biological materials containing no significant fraction of silicon in form of not naturally occurring volatile organosilicon compounds. The still incessant serious limitations and uncertainties in the determination of trace silicon in solid biological materials are discussed.

  12. Development of high-energy silicon-based anode materials for lithium-ion storage

    NASA Astrophysics Data System (ADS)

    Yi, Ran

    The emerging markets of electric vehicles (EV) and hybrid electric vehicles (HEV) generate a tremendous demand for low-cost lithium-ion batteries (LIBs) with high energy and power densities, and long cycling life. The development of such LIBs requires development of low cost, high-energy-density cathode and anode materials. Conventional anode materials in commercial LIBs are primarily synthetic graphite-based materials with a capacity of ˜370 mAh/g. Improvements in anode performance, particularly in anode capacity, are essential to achieving high energy densities in LIBs for EV and HEV applications. This dissertation focuses on development of micro-sized silicon-carbon (Si-C) composites as anode materials for high energy and power densities LIBs. First, a new, low-cost, large-scale approach was developed to prepare a micro-sized Si-C composite with excellent performance as an anode material for LIBs. The composite shows a reversible capacity of 1459 mAh/g after 200 cycles at 1 A/g (97.8% capacity retention) and excellent high rate performance of 700 mAh/g at 12.8 A/g, and also has a high tap density of 0.78 g/cm3. The structure of the composite, micro-sized as a whole, features the interconnected nanoscale size of the Si building blocks and the uniform carbon filling, which enables the maximum utilization of silicon even when the micro-sized particles break into small pieces upon cycling. To understand the effects of key parameters in designing the micro-sized Si-C composites on their electrochemical performance and explore how to optimize them, the influence of Si nanoscale building block size and carbon coating on the electrochemical performance of the micro-sized Si-C composites were investigated. It has been found that the critical Si building block size is 15 nm, which enables a high capacity without compromising the cycling stability, and that carbon coating at higher temperature improves the 1st cycle coulombic efficiency (CE) and the rate capability

  13. p -type Bi2Se3 for topological insulator and low-temperature thermoelectric applications

    NASA Astrophysics Data System (ADS)

    Hor, Y. S.; Richardella, A.; Roushan, P.; Xia, Y.; Checkelsky, J. G.; Yazdani, A.; Hasan, M. Z.; Ong, N. P.; Cava, R. J.

    2009-05-01

    The growth and elementary properties of p -type Bi2Se3 single crystals are reported. Based on a hypothesis about the defect chemistry of Bi2Se3 , the p -type behavior has been induced through low-level substitutions (1% or less) of Ca for Bi. Scanning tunneling microscopy is employed to image the defects and establish their charge. Tunneling and angle-resolved photoemission spectra show that the Fermi level has been lowered into the valence band by about 400 meV in Bi1.98Ca0.02Se3 relative to the n -type material. p -type single crystals with ab -plane Seebeck coefficients of +180μV/K at room temperature are reported. These crystals show an anomalous peak in the Seebeck coefficient at low temperatures, reaching +120μVK-1 at 7 K, giving them a high thermoelectric power factor at low temperatures. In addition to its interesting thermoelectric properties, p -type Bi2Se3 is of substantial interest for studies of technologies and phenomena proposed for topological insulators.

  14. Carbon, oxygen and their interaction with intrinsic point defects in solar silicon ribbon material: A speculative approach

    NASA Technical Reports Server (NTRS)

    Goesele, U.; Ast, D. G.

    1983-01-01

    Some background information on intrinsic point defects is provided and on carbon and oxygen in silicon in so far as it may be relevant for the efficiency of solar cells fabricated from EFG ribbon material. The co-precipitation of carbon and oxygen and especially of carbon and silicon self interstitials are discussed. A simple model for the electrical activity of carbon-self-interstitial agglomerates is presented. The self-interstitial content of these agglomerates is assumed to determine their electrical activity and that both compressive stresses (high self-interstitial content) and tensile stresses (low self-interstitial content) give rise to electrical activity of the agglomerates. The self-interstitial content of these carbon-related agglomerates may be reduced by an appropriate high temperature treatment and enhanced by a supersaturation of self-interstitials generated during formation of the p-n junction of solar cells. Oxygen present in supersaturation in carbon-rich silicon may be induced to form SiO, precipitates by self-interstitials generated during phosphorus diffusion. It is proposed that the SiO2-Si interface of the precipates gives rise to a continuum of donor stables and that these interface states are responsible for at least part of the light inhancement effects observed in oxygen containing EFG silicon after phosphorus diffusion.

  15. Effects of hole localization on limiting p-type conductivity in oxide and nitride semiconductors

    SciTech Connect

    Lyons, J. L.; Janotti, A.; Van de Walle, C. G.

    2014-01-07

    We examine how hole localization limits the effectiveness of substitutional acceptors in oxide and nitride semiconductors and explain why p-type doping of these materials has proven so difficult. Using hybrid density functional calculations, we find that anion-site substitutional impurities in AlN, GaN, InN, and ZnO lead to atomic-like states that localize on the impurity atom itself. Substitution with cation-site impurities, on the other hand, triggers the formation of polarons that become trapped on nearest-neighbor anions, generally leading to large ionization energies for these acceptors. Unlike shallow effective-mass acceptors, these two types of deep acceptors couple strongly with the lattice, significantly affecting the optical properties and severely limiting prospects for achieving p-type conductivity in these wide-band-gap materials.

  16. Electronic Structure and Doping of P-Type Transparent Conducting Oxides: Preprint

    SciTech Connect

    Wei, S.-H.; Nie, X.; Zhang, S. B.

    2002-05-01

    Transparent conducting oxides (TCOs) are a group of materials that are widely used in solar cells and other optoelectronic devices. Recently, Cu-containing p-type TCOs such as MII Cu2 O2 (MIII=Mg, Ca, Sr, Ba) and CuMIII O2 (MIII=Al, Ga, In) have been proposed. Using first-principles band structure methods, we have systematically studied the electronic and optical properties of these p-type transparent oxides. For MII Cu2 O2 , we predict that adding a small amount of Ca into Sr Cu2 O2 can increase the transparency and conductivity. For CuMIII O2 , we explained the doping and band gap anomalies in this system and proposed a new approach to search for bipolar dopable wide-gap materials.

  17. Thermal load leveling during silicon crystal growth from a melt using anisotropic materials

    DOEpatents

    Carlson, Frederick M.; Helenbrook, Brian T.

    2016-10-11

    An apparatus for growing a silicon crystal substrate comprising a heat source, an anisotropic thermal load leveling component, a crucible, and a cold plate component is disclosed. The anisotropic thermal load leveling component possesses a high thermal conductivity and may be positioned atop the heat source to be operative to even-out temperature and heat flux variations emanating from the heat source. The crucible may be operative to contain molten silicon in which the top surface of the molten silicon may be defined as a growth interface. The crucible may be substantially surrounded by the anisotropic thermal load leveling component. The cold plate component may be positioned above the crucible to be operative with the anisotropic thermal load leveling component and heat source to maintain a uniform heat flux at the growth surface of the molten silicon.

  18. Low cost solar array project. Task 1: Silicon material, gaseous melt replenishment system

    NASA Technical Reports Server (NTRS)

    Jewett, D. N.; Bates, H. E.; Hill, D. M.

    1979-01-01

    A system to combine silicon formation, by hydrogen reduction of trichlorosilane, with the capability to replenish a crystal growth system is described. A variety of process parameters to allow sizing and specification of gas handling system components was estimated.

  19. LDEF-space environmental effects on materials: Composites and silicone coatings

    NASA Technical Reports Server (NTRS)

    Petrie, Brian C.

    1991-01-01

    The objective of the Lockheed experiment is to evaluate the effects of long term low Earth orbit environments on thermal control coatings and organic matrix/fiber reinforced composites. Two diverse categories are reported: silicone coatings and composites. For composites physical and structural properties were analyzed; results are reported on mass/dimensional loss, microcracking, short beam shear, CTE, and flexural properties. The changes in thermal control properties, mass, and surface chemistry and morphology are reported and analyzed for the silicon coatings.

  20. LDEF-space environmental effects on materials: Composites and silicone coatings

    NASA Technical Reports Server (NTRS)

    Petrie, Brian C.

    1992-01-01

    The effects of long term low Earth orbit environments on thermal control coatings and organic matrix/fiber reinforced composites are discussed. Two diverse categories are reported here: silicone coatings and composites. For composites physical and structural properties were analyzed; results are reported on mass/dimensional loss, microcracking, short beam shear, coefficient of thermal expansion (CTE), and flexural properties. The changes in thermal control properties, mass, and surface chemistry and morphology are reported and analyzed for the silicone coatings.

  1. Energy Storage Materials from Nature through Nanotechnology: A Sustainable Route from Reed Plants to a Silicon Anode for Lithium-Ion Batteries.

    PubMed

    Liu, Jun; Kopold, Peter; van Aken, Peter A; Maier, Joachim; Yu, Yan

    2015-08-10

    Silicon is an attractive anode material in energy storage devices, as it has a ten times higher theoretical capacity than its state-of-art carbonaceous counterpart. However, the common process to synthesize silicon nanostructured electrodes is complex, costly, and energy-intensive. Three-dimensional (3D) porous silicon-based anode materials have been fabricated from natural reed leaves by calcination and magnesiothermic reduction. This sustainable and highly abundant silica source allows for facile production of 3D porous silicon with very good electrochemical performance. The obtained silicon anode retains the 3D hierarchical architecture of the reed leaf. Impurity leaching and gas release during the fabrication process leads to an interconnected porosity and the reductive treatment to an inside carbon coating. Such anodes show a remarkable Li-ion storage performance: even after 4000 cycles and at a rate of 10 C, a specific capacity of 420 mA h g(-1) is achieved.

  2. Low-temperature solution-processed p-type vanadium oxide for perovskite solar cells.

    PubMed

    Sun, Haocheng; Hou, Xiaomeng; Wei, Qiulong; Liu, Huawei; Yang, Kecheng; Wang, Wei; An, Qinyou; Rong, Yaoguang

    2016-06-21

    A low-temperature solution-processed inorganic p-type contact material of vanadium oxide (VOx) was developed to fabricate planar-heterojunction perovskite solar cells. Using a solvent-assisted process, high-quality uniform and compact perovskite (CH3NH3PbI3) films were deposited on VOx coated substrates. Due to the high transmittance and quenching efficiency of VOx layers, a power conversion efficiency of over 14% was achieved.

  3. Adherence of Candida albicans to denture base acrylics and silicone-based resilient liner materials with different surface finishes.

    PubMed

    Nevzatoğlu, Erdem U; Ozcan, Mutlu; Kulak-Ozkan, Yasemin; Kadir, Tanju

    2007-09-01

    This study evaluated the surface roughness and Candida albicans adherence on denture base acrylic resins and silicone-based resilient liners with different surface finishes. Four commercial denture base acrylic resins (three heat polymerized and one room temperature polymerized) and five silicone-based liner materials (two heat polymerized and three room temperature polymerized) (10 x 10 x 2 mm) were tested in this study. The materials were processed against glass or plaster or finished with a tungsten carbide bur. Surface roughness measurements were made using a profilometer with an optical scanner probe. All specimens were ultrasonically cleaned in water for 15 s, autoclave sterilized, and contaminated with C. albicans solution for adherence assay evaluation. The materials processed against the glass surface showed significantly lower surface roughness values (0.11 +/- 0.1-1.66 +/- 1.1 microm) than those of the materials processed against the dental plaster (2.61 +/- 0.2-6.12 +/- 2.8 microm) or roughening with a bur (1.48 +/- 0.2-7.05 +/- 1.2 microm; p < 0.05, one- or two-way analysis of variance). Also, the materials processed against the glass surface showed lower C. albicans adhesion (mean ranks 120.36) than those of the materials processed against the dental plaster (mean ranks 139.77) or roughening with a bur (mean ranks 143.06), but the differences were not statistically significant (p > 0.05, Kruskal-Wallis and Mann-Whitney). In all types of surface finishes, C. albicans adhesion on denture base acrylics was significantly less (mean ranks 90.18-90.40) than those of silicone liners (mean ranks 119.38-205.18; p < 0.01, Kruskal-Wallis).

  4. Liquid-phase-deposited siloxane-based capping layers for silicon solar cells

    SciTech Connect

    Veith-Wolf, Boris; Wang, Jianhui; Hannu-Kuure, Milja; Chen, Ning; Hadzic, Admir; Williams, Paul; Leivo, Jarkko; Karkkainen, Ari; Schmidt, Jan

    2015-02-02

    We apply non-vacuum processing to deposit dielectric capping layers on top of ultrathin atomic-layer-deposited aluminum oxide (AlO{sub x}) films, used for the rear surface passivation of high-efficiency crystalline silicon solar cells. We examine various siloxane-based liquid-phase-deposited (LPD) materials. Our optimized AlO{sub x}/LPD stacks show an excellent thermal and chemical stability against aluminum metal paste, as demonstrated by measured surface recombination velocities below 10 cm/s on 1.3 Ωcm p-type silicon wafers after firing in a belt-line furnace with screen-printed aluminum paste on top. Implementation of the optimized LPD layers into an industrial-type screen-printing solar cell process results in energy conversion efficiencies of up to 19.8% on p-type Czochralski silicon.

  5. Porous biomorphic silicon carbide ceramics coated with hydroxyapatite as prospective materials for bone implants.

    PubMed

    Gryshkov, Oleksandr; Klyui, Nickolai I; Temchenko, Volodymyr P; Kyselov, Vitalii S; Chatterjee, Anamika; Belyaev, Alexander E; Lauterboeck, Lothar; Iarmolenko, Dmytro; Glasmacher, Birgit

    2016-11-01

    Porous and cytocompatible silicon carbide (SiC) ceramics derived from wood precursors and coated with bioactive hydroxyapatite (HA) and HA-zirconium dioxide (HA/ZrO2) composite are materials with promising application in engineering of bone implants due to their excellent mechanical and structural properties. Biomorphic SiC ceramics have been synthesized from wood (Hornbeam, Sapele, Tilia and Pear) using a forced impregnation method. The SiC ceramics have been coated with bioactive HA and HA/ZrO2 using effective gas detonation deposition approach (GDD). The surface morphology and cytotoxicity of SiC ceramics as well as phase composition and crystallinity of deposited coatings were analyzed. It has been shown that the porosity and pore size of SiC ceramics depend on initial wood source. The XRD and FTIR studies revealed the preservation of crystal structure and phase composition of in the HA coating, while addition of ZrO2 to the initial HA powder resulted in significant decomposition of the final HA/ZrO2 coating and formation of other calcium phosphate phases. In turn, NIH 3T3 cells cultured in medium exposed to coated and uncoated SiC ceramics showed high re-cultivation efficiency as well as metabolic activity. The recultivation efficiency of cells was the highest for HA-coated ceramics, whereas HA/ZrO2 coating improved the recultivation efficiency of cells as compared to uncoated SiC ceramics. The GDD method allowed generating homogeneous HA coatings with no change in calcium to phosphorus ratio. In summary, porous and cytocompatible bio-SiC ceramics with bioactive coatings show a great promise in construction of light, robust, inexpensive and patient-specific bone implants for clinical application. PMID:27524006

  6. Porous biomorphic silicon carbide ceramics coated with hydroxyapatite as prospective materials for bone implants.

    PubMed

    Gryshkov, Oleksandr; Klyui, Nickolai I; Temchenko, Volodymyr P; Kyselov, Vitalii S; Chatterjee, Anamika; Belyaev, Alexander E; Lauterboeck, Lothar; Iarmolenko, Dmytro; Glasmacher, Birgit

    2016-11-01

    Porous and cytocompatible silicon carbide (SiC) ceramics derived from wood precursors and coated with bioactive hydroxyapatite (HA) and HA-zirconium dioxide (HA/ZrO2) composite are materials with promising application in engineering of bone implants due to their excellent mechanical and structural properties. Biomorphic SiC ceramics have been synthesized from wood (Hornbeam, Sapele, Tilia and Pear) using a forced impregnation method. The SiC ceramics have been coated with bioactive HA and HA/ZrO2 using effective gas detonation deposition approach (GDD). The surface morphology and cytotoxicity of SiC ceramics as well as phase composition and crystallinity of deposited coatings were analyzed. It has been shown that the porosity and pore size of SiC ceramics depend on initial wood source. The XRD and FTIR studies revealed the preservation of crystal structure and phase composition of in the HA coating, while addition of ZrO2 to the initial HA powder resulted in significant decomposition of the final HA/ZrO2 coating and formation of other calcium phosphate phases. In turn, NIH 3T3 cells cultured in medium exposed to coated and uncoated SiC ceramics showed high re-cultivation efficiency as well as metabolic activity. The recultivation efficiency of cells was the highest for HA-coated ceramics, whereas HA/ZrO2 coating improved the recultivation efficiency of cells as compared to uncoated SiC ceramics. The GDD method allowed generating homogeneous HA coatings with no change in calcium to phosphorus ratio. In summary, porous and cytocompatible bio-SiC ceramics with bioactive coatings show a great promise in construction of light, robust, inexpensive and patient-specific bone implants for clinical application.

  7. P-type Oxides and the Growth of Heterostructure Oxide Devices

    NASA Astrophysics Data System (ADS)

    Hosono, Hideo

    2002-03-01

    Transparent conductive oxides (TCOs) are widely used as transparent metallic electrodes for various displays and solar cells. However, even though TCO is an n-type semiconductor, there is almost no application based on the active function as a compound semiconductor. The primary reason is because most active functions in semiconductors come from the characteristic properties of p-n junction but TCOs do not have a p-type. We anticipate that new frontier of transparent oxide semiconductors (TOSs) utilizing both optical transparency and electron activity in semiconductors will be opened if a p-type TCO is realized. In 1997, we reported on CuAlO2 (thin films) as the first p-type TCO along with a chemical design concept to explore the candidate materials. After that, a series of p-type TCOs based on a Cu+ -based system have been reported following the design concept, i.e., CuGaO2, CuInO2, and SrCu2O2. In 1999, a transparent p-n heterojunction diode exhibiting a rectifying I-V characteristic was fabricated using a combination of p-SrCu2O2 (SCO) and n-ZnO. Ultraviolet-emitting diode (UV-LED) is a typical active device, which can use the features of TOSs. Thus, since the initiation of our project (October, 1999), we concentrated our effort on the fabrication of UV-LED based on transparent p-n junction composed of TOSs. The fabrication was realized(APL,77,475,2000) by the formation of p-n heterojunction composed of heteroepitaxially grown p-SCO and n-ZnO. In this talk I will review our approach to P-type TCOs and UV-LED based on PN heterojuction utilizing TCOs along with recent advances.

  8. The p-type conduction mechanism in Cu2O: a first principles study.

    PubMed

    Nolan, Michael; Elliott, Simon D

    2006-12-01

    Materials based on Cu2O are potential p-type transparent semiconducting oxides. Developing an understanding of the mechanism leading to p-type behaviour is important. An accepted origin is the formation of Cu vacancies. However, the way in which this mechanism leads to p-type properties needs to be investigated. This paper presents a first principles analysis of the origin of p-type semiconducting behaviour in Cu2O with 1.5 and 3% Cu vacancy concentrations. Plane wave density functional theory (DFT) with the Perdew-Burke Ernzerhof (PBE) exchange-correlation functional is applied. In order to investigate the applicability of DFT, we firstly show that CuO, with 50% Cu vacancies cannot be described with DFT and in order to obtain a consistent description of CuO, the DFT + U approach is applied. The resulting electronic structure is consistent with experiment, with a spin moment of 0.64 mu(B) and an indirect band gap of 1.48 eV for U = 7 eV. However, for a 3% Cu vacancy concentration in Cu2O, the DFT and DFT + U descriptions of Cu vacancies are similar, indicating that DFT is suitable for a small concentration of Cu vacancies; the formation energy of a Cu vacancy is no larger than 1.7 eV. Formation of Cu vacancies produces delocalised hole states with hole effective masses consistent with the semiconducting nature of Cu2O. These results demonstrate that the p-type semiconducting properties observed for Cu2O are explained by a small concentration of Cu vacancies. PMID:19810413

  9. Modeling of thorium (IV) ions adsorption onto a novel adsorbent material silicon dioxide nano-balls using response surface methodology.

    PubMed

    Kaynar, Ümit H; Şabikoğlu, Israfil; Kaynar, Sermin Çam; Eral, Meral

    2016-09-01

    The silicon dioxide nano-balls (nano-SiO2) were prepared for the adsorption of thorium (IV) ions from aqueous solution. The synthesized silicon dioxide nano-balls were characterized by Scanning Electron Microscopy/Energy Dispersive X-ray, X-ray Diffraction, Fourier Transform Infrared and BET surface area measurement spectroscopy. The effects of pH, concentration, temperature and the solid-liquid ratio on the adsorption of thorium by nano-balls were optimized using central composite design of response surface methodology. The interaction between four variables was studied and modelled. Furthermore, the statistical analysis of the results was done. Analysis of variance revealed that all of the single effects found statistically significant on the sorption of Th(IV). Probability F-values (F=4.64-14) and correlation coefficients (R(2)=0.99 for Th(IV)) indicate that model fit the experimental data well. The ability of this material to remove Th(IV) from aqueous solution was characterized by Langmuir, Freunlinch and Temkin adsorption isotherms. The adsorption capacity of thorium (IV) achieved 188.2mgg(-1). Thermodynamic parameters were determined and discussed. The batch adsorption condition with respect to interfering ions was tested. The results indicated that silicon dioxide nano-balls were suitable as sorbent material for adsorption and recovery of Th(IV) ions from aqueous solutions. PMID:27451112

  10. Modeling of thorium (IV) ions adsorption onto a novel adsorbent material silicon dioxide nano-balls using response surface methodology.

    PubMed

    Kaynar, Ümit H; Şabikoğlu, Israfil; Kaynar, Sermin Çam; Eral, Meral

    2016-09-01

    The silicon dioxide nano-balls (nano-SiO2) were prepared for the adsorption of thorium (IV) ions from aqueous solution. The synthesized silicon dioxide nano-balls were characterized by Scanning Electron Microscopy/Energy Dispersive X-ray, X-ray Diffraction, Fourier Transform Infrared and BET surface area measurement spectroscopy. The effects of pH, concentration, temperature and the solid-liquid ratio on the adsorption of thorium by nano-balls were optimized using central composite design of response surface methodology. The interaction between four variables was studied and modelled. Furthermore, the statistical analysis of the results was done. Analysis of variance revealed that all of the single effects found statistically significant on the sorption of Th(IV). Probability F-values (F=4.64-14) and correlation coefficients (R(2)=0.99 for Th(IV)) indicate that model fit the experimental data well. The ability of this material to remove Th(IV) from aqueous solution was characterized by Langmuir, Freunlinch and Temkin adsorption isotherms. The adsorption capacity of thorium (IV) achieved 188.2mgg(-1). Thermodynamic parameters were determined and discussed. The batch adsorption condition with respect to interfering ions was tested. The results indicated that silicon dioxide nano-balls were suitable as sorbent material for adsorption and recovery of Th(IV) ions from aqueous solutions.

  11. Quasi-perpetual discharge behaviour in p-type Ge-air batteries.

    PubMed

    Ocon, Joey D; Kim, Jin Won; Abrenica, Graniel Harne A; Lee, Jae Kwang; Lee, Jaeyoung

    2014-11-01

    Metal-air batteries continue to become attractive energy storage and conversion systems due to their high energy and power densities, safer chemistries, and economic viability. Semiconductor-air batteries - a term we first define here as metal-air batteries that use semiconductor anodes such as silicon (Si) and germanium (Ge) - have been introduced in recent years as new high-energy battery chemistries. In this paper, we describe the excellent doping-dependent discharge kinetics of p-type Ge anodes in a semiconductor-air cell employing a gelled KOH electrolyte. Owing to its Fermi level, n-type Ge is expected to have lower redox potential and better electronic conductivity, which could potentially lead to a higher operating voltage and better discharge kinetics. Nonetheless, discharge measurements demonstrated that this prediction is only valid at the low current regime and breaks down at the high current density region. The p-type Ge behaves extremely better at elevated currents, evident from the higher voltage, more power available, and larger practical energy density from a very long discharge time, possibly arising from the high overpotential for surface passivation. A primary semiconductor-air battery, powered by a flat p-type Ge as a multi-electron anode, exhibited an unprecedented full discharge capacity of 1302.5 mA h gGe(-1) (88% anode utilization efficiency), the highest among semiconductor-air cells, notably better than new metal-air cells with three-dimensional and nanostructured anodes, and at least two folds higher than commercial Zn-air and Al-air cells. We therefore suggest that this study be extended to doped-Si anodes, in order to pave the way for a deeper understanding on the discharge phenomena in alkaline metal-air conversion cells with semiconductor anodes for specific niche applications in the future.

  12. Quasi-perpetual discharge behaviour in p-type Ge-air batteries.

    PubMed

    Ocon, Joey D; Kim, Jin Won; Abrenica, Graniel Harne A; Lee, Jae Kwang; Lee, Jaeyoung

    2014-11-01

    Metal-air batteries continue to become attractive energy storage and conversion systems due to their high energy and power densities, safer chemistries, and economic viability. Semiconductor-air batteries - a term we first define here as metal-air batteries that use semiconductor anodes such as silicon (Si) and germanium (Ge) - have been introduced in recent years as new high-energy battery chemistries. In this paper, we describe the excellent doping-dependent discharge kinetics of p-type Ge anodes in a semiconductor-air cell employing a gelled KOH electrolyte. Owing to its Fermi level, n-type Ge is expected to have lower redox potential and better electronic conductivity, which could potentially lead to a higher operating voltage and better discharge kinetics. Nonetheless, discharge measurements demonstrated that this prediction is only valid at the low current regime and breaks down at the high current density region. The p-type Ge behaves extremely better at elevated currents, evident from the higher voltage, more power available, and larger practical energy density from a very long discharge time, possibly arising from the high overpotential for surface passivation. A primary semiconductor-air battery, powered by a flat p-type Ge as a multi-electron anode, exhibited an unprecedented full discharge capacity of 1302.5 mA h gGe(-1) (88% anode utilization efficiency), the highest among semiconductor-air cells, notably better than new metal-air cells with three-dimensional and nanostructured anodes, and at least two folds higher than commercial Zn-air and Al-air cells. We therefore suggest that this study be extended to doped-Si anodes, in order to pave the way for a deeper understanding on the discharge phenomena in alkaline metal-air conversion cells with semiconductor anodes for specific niche applications in the future. PMID:24975009

  13. (30)Si mole fraction of a silicon material highly enriched in (28)Si determined by instrumental neutron activation analysis.

    PubMed

    D'Agostino, Giancarlo; Di Luzio, Marco; Mana, Giovanni; Oddone, Massimo; Pramann, Axel; Prata, Michele

    2015-06-01

    The latest determination of the Avogadro constant, carried out by counting the atoms in a pure silicon crystal highly enriched in (28)Si, reached the target 2 × 10(-8) relative uncertainty required for the redefinition of the kilogram based on the Planck constant. The knowledge of the isotopic composition of the enriched silicon material is central; it is measured by isotope dilution mass spectrometry. In this work, an independent estimate of the (30)Si mole fraction was obtained by applying a relative measurement protocol based on Instrumental Neutron Activation Analysis. The amount of (30)Si isotope was determined by counting the 1266.1 keV γ-photons emitted during the radioactive decay of the radioisotope (31)Si produced via the neutron capture reaction (30)Si(n,γ)(31)Si. The x((30)Si) = 1.043(19) × 10(-6) mol mol(-1) is consistent with the value currently adopted by the International Avogadro Coordination.

  14. Facile synthesis of reduced graphene oxide-porous silicon composite as superior anode material for lithium-ion battery anodes

    NASA Astrophysics Data System (ADS)

    Jiao, Lian-Sheng; Liu, Jin-Yu; Li, Hong-Yan; Wu, Tong-Shun; Li, Fenghua; Wang, Hao-Yu; Niu, Li

    2016-05-01

    We report a new method for synthesizing reduced graphene oxide (rGO)-porous silicon composite for lithium-ion battery anodes. Rice husks were used as a as a raw material source for the synthesis of porous Si through magnesiothermic reduction process. The as-obtained composite exhibits good rate and cycling performance taking advantage of the porous structure of silicon inheriting from rice husks and the outstanding characteristic of graphene. A considerably high delithiation capacity of 907 mA h g-1 can be retained even at a rate of 16 A g-1. A discharge capacity of 830 mA h g-1 at a current density of 1 A g-1 was delivered after 200 cycles. This may contribute to the further advancement of Si-based composite anode design.

  15. Silicon spintronics.

    PubMed

    Jansen, Ron

    2012-04-23

    Worldwide efforts are underway to integrate semiconductors and magnetic materials, aiming to create a revolutionary and energy-efficient information technology in which digital data are encoded in the spin of electrons. Implementing spin functionality in silicon, the mainstream semiconductor, is vital to establish a spin-based electronics with potential to change information technology beyond imagination. Can silicon spintronics live up to the expectation? Remarkable advances in the creation and control of spin polarization in silicon suggest so. Here, I review the key developments and achievements, and describe the building blocks of silicon spintronics. Unexpected and puzzling results are discussed, and open issues and challenges identified. More surprises lie ahead as silicon spintronics comes of age.

  16. Hydrogenated amorphous silicon radiation detectors: Material parameters, radiation hardness, charge collection

    SciTech Connect

    Qureshi, S.

    1991-01-01

    For nearly two decades now hydrogenated amorphous silicon has generated considerable interest for its potential use in various device applications namely, solar cells, electrolithography, large-area electronics etc. The development of efficient and economic solar cells has been on the forefront of this research. This interest in hydrogenated amorphous silicon has been motivated by the fact that amorphous silicon can be deposited over a large area at relatively low cost compared to crystalline silicon. Hydrogenated amorphous silicon, frequently abbreviated as a-Si:H, used in solar-cell applications is a micron or less thick. The basic device structure is a p-i-n diode where the i layer is the active layer for radiation to interact. This is so because intrinsic a-Si:H has superior electrical properties in comparison to doped a-Si:H which serves the purpose of forming a potential barrier on either end of the i layer. The research presented in this dissertation was undertaken to study the properties of a-Si:H for radiation detection applications in physics and medicine.

  17. 14th Workshop on Crystalline Silicon Solar Cells& Modules: Materials and Processes; Summary of Discussion Sessions

    SciTech Connect

    Sopori, B.; Tan, T.; Sinton, R.; Swanson, D.

    2004-10-01

    The 14th Workshop discussion sessions addressed funding needs for Si research and for R&D to enhance U.S. PV manufacturing. The wrap-up session specifically addressed topics for the new university silicon program. The theme of the workshop, Crystalline Silicon Solar Cells: Leapfrogging the Barriers, was selected to reflect the astounding progress in Si PV technology during last three decades, despite a host of barriers and bottlenecks. A combination of oral, poster, and discussion sessions addressed recent advances in crystal growth technology, new cell structures and doping methods, silicon feedstock issues, hydrogen passivation and fire through metallization, and module issues/reliability. The following oral/discussion sessions were conducted: (1) Technology Update; (2) Defects and Impurities in Si/Discussion; (3) Rump Session; (4) Module Issues and Reliability/Discussion; (5) Silicon Feedstock/Discussion; (6) Novel Doping, Cells, and Hetero-Structure Designs/Discussion; (7) Metallization/Silicon Nitride Processing/Discussion; (8) Hydrogen Passivation/Discussion; (9) Characterization/Discussion; and (10) Wrap-Up. This year's workshop lasted three and a half days and, for the first time, included a session on Si modules. A rump session was held on the evening of August 8, which addressed efficiency expectations and challenges of c Si solar cells/modules. Richard King of DOE and Daren Dance of Wright Williams& Kelly (formerly of Sematech) spoke at two of the luncheon sessions. Eleven students received Graduate Student Awards from funds contributed by the PV industry.

  18. High Temperature Joining and Characterization of Joint Properties in Silicon Carbide-Based Composite Materials

    NASA Technical Reports Server (NTRS)

    Halbig, Michael C.; Singh, Mrityunjay

    2015-01-01

    Advanced silicon carbide-based ceramics and composites are being developed for a wide variety of high temperature extreme environment applications. Robust high temperature joining and integration technologies are enabling for the fabrication and manufacturing of large and complex shaped components. The development of a new joining approach called SET (Single-step Elevated Temperature) joining will be described along with the overview of previously developed joining approaches including high temperature brazing, ARCJoinT (Affordable, Robust Ceramic Joining Technology), diffusion bonding, and REABOND (Refractory Eutectic Assisted Bonding). Unlike other approaches, SET joining does not have any lower temperature phases and will therefore have a use temperature above 1315C. Optimization of the composition for full conversion to silicon carbide will be discussed. The goal is to find a composition with no remaining carbon or free silicon. Green tape interlayers were developed for joining. Microstructural analysis and preliminary mechanical tests of the joints will be presented.

  19. Process for forming retrograde profiles in silicon

    DOEpatents

    Weiner, Kurt H.; Sigmon, Thomas W.

    1996-01-01

    A process for forming retrograde and oscillatory profiles in crystalline and polycrystalline silicon. The process consisting of introducing an n- or p-type dopant into the silicon, or using prior doped silicon, then exposing the silicon to multiple pulses of a high-intensity laser or other appropriate energy source that melts the silicon for short time duration. Depending on the number of laser pulses directed at the silicon, retrograde profiles with peak/surface dopant concentrations which vary from 1-1e4 are produced. The laser treatment can be performed in air or in vacuum, with the silicon at room temperature or heated to a selected temperature.

  20. Process for forming retrograde profiles in silicon

    DOEpatents

    Weiner, K.H.; Sigmon, T.W.

    1996-10-15

    A process is disclosed for forming retrograde and oscillatory profiles in crystalline and polycrystalline silicon. The process consisting of introducing an n- or p-type dopant into the silicon, or using prior doped silicon, then exposing the silicon to multiple pulses of a high-intensity laser or other appropriate energy source that melts the silicon for short time duration. Depending on the number of laser pulses directed at the silicon, retrograde profiles with peak/surface dopant concentrations which vary are produced. The laser treatment can be performed in air or in vacuum, with the silicon at room temperature or heated to a selected temperature.

  1. WSe2 heterostructures with p-type multi-layer graphene contacts

    NASA Astrophysics Data System (ADS)

    Arefe, Ghidewon; Finney, Nathan; Seo, Dongjea; Kim, Young Duck; Chang, Damien; Cui, Xu; Kang, Kyung Nam; Jerng, Sahng-Kyoon; Chun, Seung Hyun; Yang, Eui-Hyeok; Hone, James

    Recent advances in 2D material research have opened up new opportunities to study fundamental physics and to imagine new applications for this advanced class of materials. 2D tungsten diselenide (WSe2) is a transition metal dichalcogenide (TMDC) semiconductor that is intrinsically p-type with great potential for advanced opto-electronic applications. WSe2 monolayers grown by CVD and highly p-doped PECVD multilayer graphene are used to construct 2D heterostructure p-type field effect transistors as a platform to study the potential for applications and novel physical phenomena. P-type graphene is being used to overcome the challenge of making good electrical contact to WSe2 that is Ohmic at low temperatures and to allow for the construction of an entirely 2D heterostructure. Electrical transport and novel optical effects will be studied in these WSe2 heterostructures that are fully encapsulated in hexagonal boron nitride (h-BN) in order to show greatly improved environmental stability and high mobility at low temperature due to the suppression of extrinsic scattering effects such as charge impurities, surface polar optical phonons, and absorbents from air.

  2. P-type conductivity in annealed strontium titanate

    SciTech Connect

    Poole, Violet M.; Corolewski, Caleb D.; McCluskey, Matthew D.

    2015-12-15

    Hall-effect measurements indicate p-type conductivity in bulk, single-crystal strontium titanate (SrTiO{sub 3}, or STO) samples that were annealed at 1200°C. Room-temperature mobilities above 100 cm{sup 2}/V s were measured, an order of magnitude higher than those for electrons (5-10 cm{sup 2}/V s). Average hole densities were in the 10{sup 9}-10{sup 10} cm{sup −3} range, consistent with a deep acceptor.

  3. Perspectives of High-Temperature Thermoelectric Applications and p-type and n-type Aluminoborides

    NASA Astrophysics Data System (ADS)

    Mori, T.

    2016-08-01

    A need exists to develop high-temperature thermoelectric materials which can utilize high-temperature unutilized/waste heat in thermal power plants, steelworks, factories, incinerators, etc., and also focused solar power. The thermal power plant topping application is of potential high impact since it can sizably increase the efficiency of power plants which are the major supply of electrical power for many countries. Higher borides are possible candidates for their particular high-temperature stability, generally large Seebeck coefficients, α, and intrinsic low thermal conductivity. Excellent (|α| > 200 μV/K) p-type or n-type behavior was recently achieved in the aluminoboride YAl x B14 by varying the occupancy of Al sites, x. Finding p-type and n-type counterparts has long been a difficulty of thermoelectric research not limited to borides. This paper reviews possible high-temperature thermoelectric applications, and recent developments and perspectives of thermoelectric aluminoborides.

  4. Perspectives of High-Temperature Thermoelectric Applications and p-type and n-type Aluminoborides

    NASA Astrophysics Data System (ADS)

    Mori, T.

    2016-10-01

    A need exists to develop high-temperature thermoelectric materials which can utilize high-temperature unutilized/waste heat in thermal power plants, steelworks, factories, incinerators, etc., and also focused solar power. The thermal power plant topping application is of potential high impact since it can sizably increase the efficiency of power plants which are the major supply of electrical power for many countries. Higher borides are possible candidates for their particular high-temperature stability, generally large Seebeck coefficients, α, and intrinsic low thermal conductivity. Excellent (|α| > 200 μV/K) p-type or n-type behavior was recently achieved in the aluminoboride YAl x B14 by varying the occupancy of Al sites, x. Finding p-type and n-type counterparts has long been a difficulty of thermoelectric research not limited to borides. This paper reviews possible high-temperature thermoelectric applications, and recent developments and perspectives of thermoelectric aluminoborides.

  5. Silicon/soft-carbon nanohybrid material with low expansion for high capacity and long cycle life lithium-ion battery

    NASA Astrophysics Data System (ADS)

    Kobayashi, Naoya; Inden, Yuki; Endo, Morinobu

    2016-09-01

    The present study aims at developing a silicon/soft-carbon nanohybrid material for high performance lithium-ion battery (LIB). It is composed of micronized silicon coated with so-called "soft-carbon" dispersed in soft-carbon matrix at nanometer level. This material is characterized with abundant nanosized voids with diameter of ca. 70 nm and hard bulk skeletal structure. It exhibited a long cycle life of 163 charging and discharging cycles with a large capacity of 850 mAh/g and retention rate up to 90% of the initial capacity in a half cell with Li-metal counter electrode. For this new material, the volume expansion ratio was 6.9% at a capacity level of 1100 mAh/g. This electrode capacity is approximately three times larger than that of graphite-based electrode currently used in LIB. Furthermore, this electrode retained 80.9% of its capacity at 250 cycles in a full cell with a LiCoO2 counter electrode. Addition of 5 wt % fluoroethylene carbonate (FEC) to the electrolyte improved the retention up to 81.3% after 300 cycles. These results demonstrate the usefulness and high possibility of this material as the negative electrode of LIB.

  6. Elastic constants determined by nanoindentation for p-type thermoelectric half-Heusler

    SciTech Connect

    Gahlawat, S.; Wheeler, L.; White, K. W. E-mail: kwwhite@uh.edu; He, R.; Chen, S.; Ren, Z. F. E-mail: kwwhite@uh.edu

    2014-08-28

    This paper presents a study of the elastic properties of the p-type thermoelectric half-Heusler material, Hf{sub 0.44}Zr{sub 0.44}Ti{sub 0.12}CoSb{sub 0.8}Sn{sub 0.2}, using nanoindentation. Large grain-sized polycrystalline specimens were fabricated for these measurements, providing sufficient indentation targets within single grains. Electron Backscatter Diffraction methods indexed the target grains for the correlation needed for our elastic analysis of individual single crystals for this cubic thermoelectric material. Elastic properties, including the Zener ratio and the Poisson ratio, obtained from the elasticity tensor are also reported.

  7. Metal Fluoride Inhibition of a P-type H+ Pump

    PubMed Central

    Pedersen, Jesper Torbøl; Falhof, Janus; Ekberg, Kira; Buch-Pedersen, Morten Jeppe; Palmgren, Michael

    2015-01-01

    The plasma membrane H+-ATPase is a P-type ATPase responsible for establishing electrochemical gradients across the plasma membrane in fungi and plants. This essential proton pump exists in two activity states: an autoinhibited basal state with a low turnover rate and a low H+/ATP coupling ratio and an activated state in which ATP hydrolysis is tightly coupled to proton transport. Here we characterize metal fluorides as inhibitors of the fungal enzyme in both states. In contrast to findings for other P-type ATPases, inhibition of the plasma membrane H+-ATPase by metal fluorides was partly reversible, and the stability of the inhibition varied with the activation state. Thus, the stability of the ATPase inhibitor complex decreased significantly when the pump transitioned from the activated to the basal state, particularly when using beryllium fluoride, which mimics the bound phosphate in the E2P conformational state. Taken together, our results indicate that the phosphate bond of the phosphoenzyme intermediate of H+-ATPases is labile in the basal state, which may provide an explanation for the low H+/ATP coupling ratio of these pumps in the basal state. PMID:26134563

  8. Additive-free hot-pressed silicon carbide ceramics-A material with exceptional mechanical properties

    DOE PAGESBeta

    Sajgalik, P.; Sedlacek, J.; Lences, Z.; Dusza, J.; Lin, H. -T.

    2015-12-30

    Densification of silicon carbide without any sintering aids by hot-pressing and rapid hot pressing was investigated. Full density (>99% t.d.) has been reached at 1850 °C, a temperature of at least 150-200 °C lower compared to the up to now known solid state sintered silicon carbide powders. Silicon carbide was freeze granulated and heat treated prior the densification. Furthermore, evolution of microstructure, mechanical properties and creep behavior were evaluated and compared to reference ceramics from as received silicon carbide powder as well as those of commercial one. Novel method results in dense ceramics with Vickers hardness and indentation fracture toughnessmore » of 29.0 GPa and 5.25 MPam1/2, respectively. Moreover, the creep rate of 3.8 x 10–9 s–1 at 1450 °C and the load of 100 MPa is comparable to the commercial α-SiC solid state sintered at 2150 °C.« less

  9. Additive-free hot-pressed silicon carbide ceramics-A material with exceptional mechanical properties

    SciTech Connect

    Sajgalik, P.; Sedlacek, J.; Lences, Z.; Dusza, J.; Lin, H. -T.

    2015-12-30

    Densification of silicon carbide without any sintering aids by hot-pressing and rapid hot pressing was investigated. Full density (>99% t.d.) has been reached at 1850 °C, a temperature of at least 150-200 °C lower compared to the up to now known solid state sintered silicon carbide powders. Silicon carbide was freeze granulated and heat treated prior the densification. Furthermore, evolution of microstructure, mechanical properties and creep behavior were evaluated and compared to reference ceramics from as received silicon carbide powder as well as those of commercial one. Novel method results in dense ceramics with Vickers hardness and indentation fracture toughness of 29.0 GPa and 5.25 MPam1/2, respectively. Moreover, the creep rate of 3.8 x 10–9 s–1 at 1450 °C and the load of 100 MPa is comparable to the commercial α-SiC solid state sintered at 2150 °C.

  10. Process research on Semix Silicon Material (PROSSM). Quarterly report No. 5, December 1, 1981-February 28, 1982

    SciTech Connect

    Wohlgemuth, J H; Warfield, D B

    1982-01-01

    Emphasis was shifted from the development of a cost-effective process sequence to research designed to understand the mechanisms of photovoltaic conversion in semicrystalline silicon. With this change has gone a change of title from Module Experimental Process System Development Unit (MEPSDU) to Process Research of Semix Silicon Material (PROSSM). Efforts are now underway to prepare a revised program plan with emphasis on determining the mechanisms limiting voltage and current collection in the semicrystalline silicon. The efforts reported concern work done before the change in emphasis and so the continued development of the cost-effective process sequence is reported. A cost-effective process sequence was identified, equipment was designed to implement a 6.6 MW per year automated production line, and a cost analysis projected a $0.56 per watt cell add-on cost for this line. Four process steps were developed for this program: glass bead back clean-up; hot spray antireflective coating; wave-soldering of fronts; ion milling for edging. While spray dopants were advertised as an off the shelf developed product, they proved to be unreliable with shorter than advertised shelf life. Equipment for handling and processing solar cells is available for all of the cell processing steps identified in this program. During this quarter efforts included work on spray dopant, edging, AR coating, wave soldering and fluxing, ion milling and cost analysis.

  11. Investigation of solar cells fabricated on low-cost silicon sheet materials using 1 MeV electron irradiation

    NASA Technical Reports Server (NTRS)

    Kachare, A. H.; Hyland, S. L.; Garlick, G. F. J.

    1981-01-01

    The use of high energy electron irradiation is investigated as a controlled means to study in more detail the junction depletion layer processes of solar cells made on various low-cost silicon sheet materials. Results show that solar cells made on Czochralski grown silicon exhibit enhancement of spectral response in the shorter wavelength region when irradiated with high energy electrons. The base region damage can be reduced by subsequent annealing at 450 C which restores the degraded longer wavelength response, although the shorter wavelength enhancement persists. The second diode component of the cell dark forward bias current is also reduced by electron irradiation, while thermal annealing at 450 C without electron irradiation can also produce these same effects. Electron irradiation produces small changes in the shorter wavelength spectral responses and junction improvements in solar cells made on WEB, EFG, and HEM silicon. It is concluded that these beneficial effects on cell characteristics are due to the reduction of oxygen associated deep level recombination centers in the N(+) diffused layer and in the junction.

  12. RETRACTION: Electronic characteristics of n-type nanocrystalline/p-type crystalline silicon heterostructure

    NASA Astrophysics Data System (ADS)

    Wei, Wensheng; Wang, Tianmin; He, Yuliang

    2008-03-01

    It has come to the attention of IOP Publishing that this article should not have been submitted for publication owing to its substantial replication of an earlier paper (Wensheng Wei, Tianmin Wang and Yuliang He 2008 Investigation on high mobility nanocrystalline Si with crystalline Si heterostructure Superlattices and Microstructures 41 216-226). Consequently this paper has been retracted by IOP Publishing.

  13. PREFACE: E-MRS 2012 Spring Meeting, Symposium M: More than Moore: Novel materials approaches for functionalized Silicon based Microelectronics

    NASA Astrophysics Data System (ADS)

    Wenger, Christian; Fompeyrine, Jean; Vallée, Christophe; Locquet, Jean-Pierre

    2012-12-01

    More than Moore explores a new area of Silicon based microelectronics, which reaches beyond the boundaries of conventional semiconductor applications. Creating new functionality to semiconductor circuits, More than Moore focuses on motivating new technological possibilities. In the past decades, the main stream of microelectronics progresses was mainly powered by Moore's law, with two focused development arenas, namely, IC miniaturization down to nano scale, and SoC based system integration. While the microelectronics community continues to invent new solutions around the world to keep Moore's law alive, there is increasing momentum for the development of 'More than Moore' technologies which are based on silicon technologies but do not simply scale with Moore's law. Typical examples are RF, Power/HV, Passives, Sensor/Actuator/MEMS or Bio-chips. The More than Moore strategy is driven by the increasing social needs for high level heterogeneous system integration including non-digital functions, the necessity to speed up innovative product creation and to broaden the product portfolio of wafer fabs, and the limiting cost and time factors of advanced SoC development. It is believed that More than Moore will add value to society on top of and beyond advanced CMOS with fast increasing marketing potentials. Important key challenges for the realization of the 'More than Moore' strategy are: perspective materials for future THz devices materials systems for embedded sensors and actuators perspective materials for epitaxial approaches material systems for embedded innovative memory technologies development of new materials with customized characteristics The Hot topics covered by the symposium M (More than Moore: Novel materials approaches for functionalized Silicon based Microelectronics) at E-MRS 2012 Spring Meeting, 14-18 May 2012 have been: development of functional ceramics thin films New dielectric materials for advanced microelectronics bio- and CMOS compatible

  14. Preparation of Gold Nanoparticles Deposited Silicon Thin Film Electrode by Self-Assembly Method for the Employment of an Anode Material for Lithium Secondary Batteries.

    PubMed

    Halim, Martin; Kim, Jung Sub; Nguyen, Si Hieu; Jeon, Bup Ju; Lee, Joong Kee

    2015-10-01

    This work describes a self-assembly method of gold nanoparticles coating on the surface of silicon thin films for the anode material of lithium secondary batteries. The preparation of the silicon thin films was carried out by electron cyclotron resonance metal organic chemical vapor deposition (ECR-MOCVD) process. The obtained films were further coated with (3-aminopropyl)-trimethoxysilane (APTMS) which has a role to bind the oxygen functional groups on Si surface and the gold nanoparticles. The dispersed gold nanoparticles on the surface of silicon thin films could be prepared due to self-assembly phenomena which interact between attraction and repulsion in gold nanoparticles colloidal solution (GNCS). The use of reducing agent of sodium citrate and tannic acid in GNCS significantly affected the size of gold nanoparticle in our experimental range. Based on our experimental results, the higher reversible capacity was exhibited for the silicon that was immersed in the GNCS consisted of only sodium citrate. The GNCS consisted of both sodium citrate and tannic acid produced severe coagulated nanoparticles when deposited on the silicon surface and thus inhibited the lithium movement from electrolyte to silicon surface. Consequently, the reversible capacity of silicon anode material with coagulated gold nanoparticles coating showed the reduced performance. PMID:26726492

  15. Foreign Object Damage in a Gas-Turbine Grade Silicon Nitride by Spherical Projectiles of Various Materials

    NASA Technical Reports Server (NTRS)

    Choi, Sung R.; Racz, Zsolt; Bhatt, Ramakrishna T.; Brewer, David N.

    2006-01-01

    Assessments of foreign object damage (FOD) of a commercial, gas-turbine grade, in situ toughened silicon nitride ceramic (AS800, Honeywell Ceramics Components) were made using four different projectile materials at ambient temperature. AS800 flexure target specimens rigidly supported were impacted at their centers in a velocity range from 50 to 450 m/s by spherical projectiles with a diameter of 1.59 mm. Four different projectile materials were used including hardened steel, annealed steel, silicon nitride ceramic, and brass. Post-impact strength of each target specimen impacted was determined as a function of impact velocity to appraise the severity of local impact damage. For a given impact velocity, the degree of strength degradation was greatest for ceramic balls, least for brass balls, and intermediate for annealed and hardened steel balls. For steel balls, hardened projectiles yielded more significant impact damage than annealed counterparts. The most important material parameter affecting FOD was identified as hardness of projectiles. Impact load as a function of impact velocity was quasi-statically estimated based on both impact and static indentation associated data.

  16. Caramel popcorn shaped silicon particle with carbon coating as a high performance anode material for Li-ion batteries.

    PubMed

    He, Meinan; Sa, Qina; Liu, Gao; Wang, Yan

    2013-11-13

    Silicon is a very promising anode material for lithium ion batteries. It has a 4200 mAh/g theoretical capacity, which is ten times higher than that of commercial graphite anodes. However, when lithium ions diffuse to Si anodes, the volume of Si will expand to almost 400% of its initial size and lead to the crack of Si. Such a huge volume change and crack cause significant capacity loss. Meanwhile, with the crack of Si particles, the conductivity between the electrode and the current collector drops. Moreover, the solid electrolyte interphase (SEI), which is generated during the cycling, reduces the discharge capacity. These issues must be addressed for widespread application of this material. In this work, caramel popcorn shaped porous silicon particles with carbon coating are fabricated by a set of simple chemical methods as active anode material. Si particles are etched to form a porous structure. The pores in Si provide space for the volume expansion and liquid electrolyte diffusion. A layer of amorphous carbon is formed inside the pores, which gives an excellent isolation between the Si particle and electrolyte, so that the formation of the SEI layer is stabilized. Meanwhile, this novel structure enhances the mechanical properties of the Si particles, and the crack phenomenon caused by the volume change is significantly restrained. Therefore, an excellent cycle life under a high rate for the novel Si electrode is achieved. PMID:24111737

  17. Process feasibility study in support of silicon material Task I. Quarterly technical progress report (XIX), March 1-May 31, 1980

    SciTech Connect

    Yaws, C.L.; Li, K.Y.

    1980-06-01

    Analyses of process system properties were continued for chemical materials important in the production of silicon. Major physical, thermodynamic and transport property data are reported for silicon including critical constants, vapor pressure, heat of vaporization, heat of sublimation, heat capacity, density, surface tension, viscosity and thermal conductivity. The property data covers both liquid and solid phases and are reported as a function of temperature for rapid engineering usage. Major efforts in chemical engineering analysis centered on the HSC process (Hemlock Semiconductor Corporation). The approach for the process involves performing initial analysis for DCS production (dichlorosilane) and then perorming analysis of polysilicon production from the DCS. For the DCS production, status and progress are reported for primary activities of base case conditions (65%), reaction chemistry (65%), process flowsheet (60%), material balance (50%) and energy balance (40%). Two key features - redistribution reactor relocation and final distillation - are introduced to increase yield of DCS by about 10 to 20%, help insure purity and reduce potential dust (fine particle nucleation) components in the polysilicon feed material. The preliminary flowsheet for DCS production was forwarded to Hemlock Semiconductor Corporation for initial screening and review. Hemlock Semiconductor is in agreement in regards to relocation of the redistribution reactor to increase yield. Additional follow-up review is in progress including boron removal options identified by Hemlock Semiconductor. 166 references.

  18. Development and Evaluation of Die Materials for Use in the Growth of Silicon Ribbons by the Inverted Ribbon Growth Process. Task 2: LSSA Project

    NASA Technical Reports Server (NTRS)

    Duffy, M. T.; Berkman, S.; Moss, H. I.; Cullen, G. W.

    1978-01-01

    Several ribbon growth experiments were performed from V-shaped dies coated with CVD Si3N4. The most significant result was the ability to perform five consecutive growth runs from the same die without mechanical degradation of the die through temperature cycling. The die was made from vitreous carbon coated with CVD Si3N4. Silicon oxynitride, Si2N2O, was examined with respect to thermal stability in contact with molten silicon. The results of X-ray analysis indicate that this material is converted to both alpha - and beta-Si3N4 in the presence of molten silicon. Experiments on the stability of CVD SiOxNy shoe that this material can be maintained in contact with molten silicon (sessile drop test) for greater than 30 h at 1450 C without total decompositon. These layers are converted mainly to beta-Si3N4.

  19. High-Resolution p-Type Metal Oxide Semiconductor Nanowire Array as an Ultrasensitive Sensor for Volatile Organic Compounds.

    PubMed

    Cho, Soo-Yeon; Yoo, Hae-Wook; Kim, Ju Ye; Jung, Woo-Bin; Jin, Ming Liang; Kim, Jong-Seon; Jeon, Hwan-Jin; Jung, Hee-Tae

    2016-07-13

    The development of high-performance volatile organic compound (VOC) sensor based on a p-type metal oxide semiconductor (MOS) is one of the important topics in gas sensor research because of its unique sensing characteristics, namely, rapid recovery kinetics, low temperature dependence, high humidity or thermal stability, and high potential for p-n junction applications. Despite intensive efforts made in this area, the applications of such sensors are hindered because of drawbacks related to the low sensitivity and slow response or long recovery time of p-type MOSs. In this study, the VOC sensing performance of a p-type MOS was significantly enhanced by forming a patterned p-type polycrystalline MOS with an ultrathin, high-aspect-ratio (∼25) structure (∼14 nm thickness) composed of ultrasmall grains (∼5 nm size). A high-resolution polycrystalline p-type MOS nanowire array with a grain size of ∼5 nm was fabricated by secondary sputtering via Ar(+) bombardment. Various p-type nanowire arrays of CuO, NiO, and Cr2O3 were easily fabricated by simply changing the sputtering material. The VOC sensor thus fabricated exhibited higher sensitivity (ΔR/Ra = 30 at 1 ppm hexane using NiO channels), as well as faster response or shorter recovery time (∼30 s) than that of previously reported p-type MOS sensors. This result is attributed to the high resolution and small grain size of p-type MOSs, which lead to overlap of fully charged zones; as a result, electrical properties are predominantly determined by surface states. Our new approach may be used as a route for producing high-resolution MOSs with particle sizes of ∼5 nm within a highly ordered, tall nanowire array structure.

  20. High-Resolution p-Type Metal Oxide Semiconductor Nanowire Array as an Ultrasensitive Sensor for Volatile Organic Compounds.

    PubMed

    Cho, Soo-Yeon; Yoo, Hae-Wook; Kim, Ju Ye; Jung, Woo-Bin; Jin, Ming Liang; Kim, Jong-Seon; Jeon, Hwan-Jin; Jung, Hee-Tae

    2016-07-13

    The development of high-performance volatile organic compound (VOC) sensor based on a p-type metal oxide semiconductor (MOS) is one of the important topics in gas sensor research because of its unique sensing characteristics, namely, rapid recovery kinetics, low temperature dependence, high humidity or thermal stability, and high potential for p-n junction applications. Despite intensive efforts made in this area, the applications of such sensors are hindered because of drawbacks related to the low sensitivity and slow response or long recovery time of p-type MOSs. In this study, the VOC sensing performance of a p-type MOS was significantly enhanced by forming a patterned p-type polycrystalline MOS with an ultrathin, high-aspect-ratio (∼25) structure (∼14 nm thickness) composed of ultrasmall grains (∼5 nm size). A high-resolution polycrystalline p-type MOS nanowire array with a grain size of ∼5 nm was fabricated by secondary sputtering via Ar(+) bombardment. Various p-type nanowire arrays of CuO, NiO, and Cr2O3 were easily fabricated by simply changing the sputtering material. The VOC sensor thus fabricated exhibited higher sensitivity (ΔR/Ra = 30 at 1 ppm hexane using NiO channels), as well as faster response or shorter recovery time (∼30 s) than that of previously reported p-type MOS sensors. This result is attributed to the high resolution and small grain size of p-type MOSs, which lead to overlap of fully charged zones; as a result, electrical properties are predominantly determined by surface states. Our new approach may be used as a route for producing high-resolution MOSs with particle sizes of ∼5 nm within a highly ordered, tall nanowire array structure. PMID:27304752

  1. Material synthesis for silicon integrated-circuit applications using ion implantation

    NASA Astrophysics Data System (ADS)

    Lu, Xiang

    As devices scale down into deep sub-microns, the investment cost and complexity to develop more sophisticated device technologies have increased substantially. There are some alternative potential technologies, such as silicon-on-insulator (SOI) and SiGe alloys, that can help sustain this staggering IC technology growth at a lower cost. Surface SiGe and SiGeC alloys with germanium peak composition up to 16 atomic percent are formed using high-dose ion implantation and subsequent solid phase epitaxial growth. RBS channeling spectra and cross-sectional TEM studies show that high quality SiGe and SiGeC crystals with 8 atomic percent germanium concentration are formed at the silicon surface. Extended defects are formed in SiGe and SiGeC with 16 atomic percent germanium concentration. X-ray diffraction experiments confirm that carbon reduces the lattice strain in SiGe alloys but without significant crystal quality improvement as detected by RBS channeling spectra and XTEM observations. Separation by plasma implantation of oxygen (SPIMOX) is an economical method for SOI wafer fabrication. This process employs plasma immersion ion implantation (PIII) for the implantation of oxygen ions. The implantation rate for Pm is considerably higher than that of conventional implantation. The feasibility of SPIMOX has been demonstrated with successful fabrication of SOI structures implementing this process. Secondary ion mass spectrometry (SIMS) analysis and cross-sectional transmission electron microscopy (XTEM) micrographs of the SPIMOX sample show continuous buried oxide under single crystal overlayer with sharp silicon/oxide interfaces. The operational phase space of implantation condition, oxygen dose and annealing requirement has been identified. Physical mechanisms of hydrogen induced silicon surface layer cleavage have been investigated using a combination of microscopy and hydrogen profiling techniques. The evolution of the silicon cleavage phenomenon is recorded by a series

  2. Introducing porous silicon as a sacrificial material to obtain cavities in substrate of SOI wafers and a getter material for MEMS devices

    NASA Astrophysics Data System (ADS)

    Mohammad, Wajihuddin

    Microelectromechanical system (MEMS) resonators have been a subject of research for more than four decades. The reason is the huge potential they possess for frequency applications. The use of a MEMS resonator as the timing element has an experimental history and huge progress has been made in this direction. Vacuum encapsulated MEMS resonators are required for high precision frequency control. Hence, a device with a high quality factor and durability is needed. In this effort, a new process for producing a cavity in the substrate of Silicon on insulator (SOI) MEMS devices and augmenting it with a getter using porous silicon is developed. The process involves a mask-less, self-aligned cost effective electrochemical etching process. A 10 mum cavity is introduced in the substrate of SOI dies. This helps in increasing the packaging volume of the SOI resonators along with mitigating the viscous damping effects. The stiction problem in MEMS devices is effectively eliminated and millimeter long slender MEMS structures do not get stuck to the substrate. It also helps in reducing the parasitic capacitance between the device side and the substrate. The porous silicon getter is introduced as a getter material for vacuum encapsulated MEMS devices. This getter needs no external mask and is self-aligned. It requires no external heat or additional materials to operate. The highly reactive porous silicon can readily react with the oxygen gas and form an oxide layer that can trap other gas molecules. This helps in maintaining low pressures in the cavity of the bonded MEMS resonators. A tuning fork resonator with a resonant frequency of 245 kHz was used to realize the benefits of the cavity and the getter. It was observed that the unpackaged device with the cavity in the substrate showed two times better quality factor at different pressures, than the device with no cavity. In order to understand the benefits of porous silicon as a getter, the MEMS devices (one with only a cavity

  3. Purified silicon production system

    DOEpatents

    Wang, Tihu; Ciszek, Theodore F.

    2004-03-30

    Method and apparatus for producing purified bulk silicon from highly impure metallurgical-grade silicon source material at atmospheric pressure. Method involves: (1) initially reacting iodine and metallurgical-grade silicon to create silicon tetraiodide and impurity iodide byproducts in a cold-wall reactor chamber; (2) isolating silicon tetraiodide from the impurity iodide byproducts and purifying it by distillation in a distillation chamber; and (3) transferring the purified silicon tetraiodide back to the cold-wall reactor chamber, reacting it with additional iodine and metallurgical-grade silicon to produce silicon diiodide and depositing the silicon diiodide onto a substrate within the cold-wall reactor chamber. The two chambers are at atmospheric pressure and the system is open to allow the introduction of additional source material and to remove and replace finished substrates.

  4. Demethoxycurcumin Is A Potent Inhibitor of P-Type ATPases from Diverse Kingdoms of Life.

    PubMed

    Dao, Trong Tuan; Sehgal, Pankaj; Tung, Truong Thanh; Møller, Jesper Vuust; Nielsen, John; Palmgren, Michael; Christensen, Søren Brøgger; Fuglsang, Anja Thoe

    2016-01-01

    P-type ATPases catalyze the active transport of cations and phospholipids across biological membranes. Members of this large family are involved in a range of fundamental cellular processes. To date, a substantial number of P-type ATPase inhibitors have been characterized, some of which are used as drugs. In this work a library of natural compounds was screened and we first identified curcuminoids as plasma membrane H+-ATPases inhibitors in plant and fungal cells. We also found that some of the commercial curcumins contain several curcuminoids. Three of these were purified and, among the curcuminoids, demethoxycurcumin was the most potent inhibitor of all tested P-type ATPases from fungal (Pma1p; H+-ATPase), plant (AHA2; H+-ATPase) and animal (SERCA; Ca2+-ATPase) cells. All three curcuminoids acted as non-competitive antagonist to ATP and hence may bind to a highly conserved allosteric site of these pumps. Future research on biological effects of commercial preparations of curcumin should consider the heterogeneity of the material. PMID:27644036

  5. Towards p-type doping of ZnO by ion implantation

    SciTech Connect

    Coleman, V; Tan, H H; Jagadish, C; Kucheyev, S; Phillips, M; Zou, J

    2005-01-18

    Zinc oxide is a very attractive material for a range of optoelectronic devices including blue light-emitting diodes and laser diodes. Though n-type doping has been successfully achieved, p-type doing of ZnO is still a challenge that must be overcome before p-n junction devices can be realized. Ion implantation is widely used in the microelectronics industry for selective area doping and device isolation. Understanding damage accumulation and recrystallization processes is important for achieving selective area doping. In this study, As (potential p-type dopant) ion implantation and annealing studies were carried out. ZnO samples were implanted with high dose (1.4 x 10{sup 17} ions/cm{sup 2}) 300 keV As ions at room temperature. Furnace annealing of samples in the range of 900 C to 1200 C was employed to achieve recrystallization of amorphous layers and electrical activation of the dopant. Rutherford backscattering/channeling spectrometry, transmission electron microscopy and cathodolumiescence spectroscopy were used to monitor damage accumulation and annihilation behavior in ZnO. Results of this study have significant implications for p-type doing of ZnO by ion implantation.

  6. Demethoxycurcumin Is A Potent Inhibitor of P-Type ATPases from Diverse Kingdoms of Life

    PubMed Central

    Dao, Trong Tuan; Sehgal, Pankaj; Tung, Truong Thanh; Møller, Jesper Vuust; Nielsen, John; Palmgren, Michael; Christensen, Søren Brøgger

    2016-01-01

    P-type ATPases catalyze the active transport of cations and phospholipids across biological membranes. Members of this large family are involved in a range of fundamental cellular processes. To date, a substantial number of P-type ATPase inhibitors have been characterized, some of which are used as drugs. In this work a library of natural compounds was screened and we first identified curcuminoids as plasma membrane H+-ATPases inhibitors in plant and fungal cells. We also found that some of the commercial curcumins contain several curcuminoids. Three of these were purified and, among the curcuminoids, demethoxycurcumin was the most potent inhibitor of all tested P-type ATPases from fungal (Pma1p; H+-ATPase), plant (AHA2; H+-ATPase) and animal (SERCA; Ca2+-ATPase) cells. All three curcuminoids acted as non-competitive antagonist to ATP and hence may bind to a highly conserved allosteric site of these pumps. Future research on biological effects of commercial preparations of curcumin should consider the heterogeneity of the material. PMID:27644036

  7. 18th Workshop on Crystalline Silicon Solar Cells and Modules: Materials and Processes; Workshop Proceedings, 3-6 August 2008, Vail, Colorado

    SciTech Connect

    Sopori, B. L.

    2008-09-01

    The National Center for Photovoltaics sponsored the 18th Workshop on Crystalline Silicon Solar Cells & Modules: Materials and Processes, held in Vail, CO, August 3-6, 2008. This meeting provided a forum for an informal exchange of technical and scientific information between international researchers in the photovoltaic and relevant non-photovoltaic fields. The theme of this year's meeting was 'New Directions for Rapidly Growing Silicon Technologies.'

  8. p-Type NiO Hybrid Visible Photodetector.

    PubMed

    Mallows, John; Planells, Miquel; Thakare, Vishal; Bhosale, Reshma; Ogale, Satishchandra; Robertson, Neil

    2015-12-23

    A novel hybrid visible-light photodetector was created using a planar p-type inorganic NiO layer in a junction with an organic electron acceptor layer. The effect of different oxygen pressures on formation of the NiO layer by pulsed laser deposition shows that higher pressure increases the charge carrier density of the film and lowers the dark current in the device. The addition of a monolayer of small molecules containing conjugated π systems and carboxyl groups at the device interface was also investigated and with correct alignment of the energy levels improves the device performance with respect to the quantum efficiency, responsivity, and photogeneration. The thickness of the organic layer was also optimized for the device, giving a responsivity of 1.54 × 10(-2) A W(-1) in 460 nm light. PMID:26654105

  9. p-Type NiO Hybrid Visible Photodetector.

    PubMed

    Mallows, John; Planells, Miquel; Thakare, Vishal; Bhosale, Reshma; Ogale, Satishchandra; Robertson, Neil

    2015-12-23

    A novel hybrid visible-light photodetector was created using a planar p-type inorganic NiO layer in a junction with an organic electron acceptor layer. The effect of different oxygen pressures on formation of the NiO layer by pulsed laser deposition shows that higher pressure increases the charge carrier density of the film and lowers the dark current in the device. The addition of a monolayer of small molecules containing conjugated π systems and carboxyl groups at the device interface was also investigated and with correct alignment of the energy levels improves the device performance with respect to the quantum efficiency, responsivity, and photogeneration. The thickness of the organic layer was also optimized for the device, giving a responsivity of 1.54 × 10(-2) A W(-1) in 460 nm light.

  10. Characterization of the impurities in tungsten/silicon-germanium contacts

    SciTech Connect

    Gregg, H.A. Sr.

    1986-03-26

    Secondary ion mass spectrometry and Auger electron spectrometry depth profiling were used to determine impurity distributions in sputter deposited tungsten films over N-type and P-type 80/20 silicon-germanium elements of thermoelectric devices. These analyses showed that silicon, oxygen, sodium, boron, and phosphorous were present as impurities in the tungsten film. All these impurities except oxygen and sodium came from the substrate. Oxygen was gettered by the tungsten films, while sodium was possibly the result of sample handling. Further, the results from this study indicate that an oxide build-up, primarily at the tungsten/silicon-germanium interface of the N-type materials, is the major contributor to contact resistance in thermoelectric devices.

  11. Silicon materials task of the low-cost solar array project. Phase 4: Effects of impurities and processing on silicon solar cells

    NASA Technical Reports Server (NTRS)

    Hopkins, R. H.; Hanes, M. H.; Davis, J. R.; Rohatgi, A.; Rai-Choudhury, P.; Mollenkopf, H. C.

    1981-01-01

    The effects of impurities, various thermochemical processes, and any impurity-process interactions upon the performance of terrestrial solar cells are defined. The results form a basis for silicon producers, wafer manufacturers, and cell fabricators to develop appropriate cost benefit relationships for the use of less pure, less costly solar grade silicon.

  12. Process Research On Polycrystalline Silicon Material (PROPSM). [flat plate solar array project

    NASA Technical Reports Server (NTRS)

    Culik, J. S.

    1983-01-01

    The performance-limiting mechanisms in large-grain (greater than 1 to 2 mm in diameter) polycrystalline silicon solar cells were investigated by fabricating a matrix of 4 sq cm solar cells of various thickness from 10 cm x 10 cm polycrystalline silicon wafers of several bulk resistivities. Analysis of the illuminated I-V characteristics of these cells suggests that bulk recombination is the dominant factor limiting the short-circuit current. The average open-circuit voltage of the polycrystalline solar cells is 30 to 70 mV lower than that of co-processed single-crystal cells; the fill-factor is comparable. Both open-circuit voltage and fill-factor of the polycrystalline cells have substantial scatter that is not related to either thickness or resistivity. This implies that these characteristics are sensitive to an additional mechanism that is probably spatial in nature. A damage-gettering heat-treatment improved the minority-carrier diffusion length in low lifetime polycrystalline silicon, however, extended high temperature heat-treatment degraded the lifetime.

  13. Germanium-on-Silicon Strain Engineered Materials for Improved Device Performance Grown by Chemical Vapor Deposition

    NASA Astrophysics Data System (ADS)

    Bharathan, Jayesh Moorkoth

    The primary goal of this research is to develop a chemical vapor deposition process for growing epitaxial films of germanium on silicon (001) substrates with two-dimensional (2-D) morphology, and a low density of threading dislocations. Growth was carried out in a reduced-pressure chemical vapor deposition (RPCVD) system by a two-step growth technique. An accurate knowledge of elastic constants of thin films is important in understanding the effect of strain on material properties. Residual thermal strain was used to measure the Poisson ratio of Ge films grown on Si(001) substrates, by the sin2Psi method and highresolution x-ray diffraction. The Poisson ratio of the Ge films was measured to be 0.25, compared to the bulk value of 0.27. The result was found to be independent of film thickness and defect density, which confirmed that the strain is associated with the elastic response of the film. The study showed that the use of Poisson ratio instead of bulk compliance values yields a more accurate description of the state of in-plane strain present in the film. The experimentally measured in-plane strain in Ge films was found to be lower than the theoretical calculations based on the differential thermal expansion coefficients of Si and Ge. The mechanism of thermal misfit strain relaxation in epitaxial Ge films grown on Si(001) substrates was investigated by x-ray diffraction, and transmission electron microscopy. Lattice misfit strain associated with Ge/(001)Si mismatched epitaxy is relieved by a network of Lomer edge misfit dislocations during the first step of the growth technique. However, thermal misfit strain energy during growth is relieved by interdiffusion mechanism at the heterointerface. Two SiGe compositions containing 0.5 and 6.0 atomic percent Si were detected that relieve the thermal mismatch strain associated with the two steps of the growth process. This study discusses the importance of interdiffusion mechanism in relieving small misfit strains

  14. Silicon materials task of the low-cost solar array project. Phase 4: Effects of impurities and processing on silicon solar cells

    NASA Astrophysics Data System (ADS)

    Hopkins, R. H.; Hanes, M. H.; Davis, J. R.; Rohatgi, A.; Raichoudhury, P.; Mollenkopf, H. C.

    1981-01-01

    The results of the study form a basis for silicon producers, wafer manufacturers, and cell fabricators to develop appropriate cost-benefit relationships for the use of less pure, less costly solar grade silicon. Cr is highly mobile in silicon even at temperatures as low as 600 C. Contrasting with earlier data for Mo, Ti, and V, Cr concentrations vary from place to place in polycrystalline silicon wafers and the electrically-active Cr concentration in the polysilicon is more than an order of magnitude smaller than would be projected from single crystal impurity data. We hypothesize that Cr diffuses during ingot cooldown after growth, preferentially segregates to grain and becomes electrically deactivated. Accelerated aging data from Ni-contaminated silicon imply that no significant impurity-induced cell performance reduction should be expected over a twenty year device lifetime.

  15. Thermoelectric Properties of Sintered n-Type and p-Type Tellurides

    NASA Astrophysics Data System (ADS)

    Hassel, J.; Tervo, J.

    2013-07-01

    Characterization of powder-metallurgically manufactured (Bi x Sb1- x )2(Te y Se1- y )3 thermoelectric materials is presented. The manufacturing methods were spark plasma sintering (SPS) and hot isostatic pressing (HIP). x-Ray diffraction (XRD) and density measurements as well as transport characterization and scanning electron microscopy were performed on the materials. It is shown that both sintering techniques yield reasonable thermoelectric characteristics for p-type ( x = 0.2, y = 1) as well as n-type ( x = 0.95, y = 0.95) materials. Insight into the underlying reasons such as the scattering processes limiting the characteristics is gained by fitting experimental transport data using a theoretical model. The limitations and further optimization issues of our approach in thermoelectric material preparation are discussed.

  16. High-resolution solid-state NMR study of the occurrence and thermal transformations of silicon-containing species in biomass materials

    SciTech Connect

    Freitas, J.C.C.; Emmerich, F.G.; Bonagamba, T.J.

    2000-03-01

    The occurrence of silicon in two kinds of biomass (rice hulls and endocarp of babassu coconut) and the thermal transformations taking place in these materials under heat treatments are studied here. The authors report also the production, characterization, and study of carbonaceous materials with high SiC content through the carbothermal reduction of silica, using these natural precursors. X-ray diffraction, scanning electron microscopy, and {sup 13}C and {sup 29}Si room temperature high-resolution solid-state NMR measurements are used in the characterization and study of the materials as well as the process of SiC formation. Important conclusions about the nature of silicon in these types of biomass and the effects of heat treatments on the structure of silicon-containing species are derived from the results presented. It is shown that silicon in these materials occurs in two distinct forms: amorphous hydrated silica and organically bound silicon species. The influence of spin-lattice relaxation dynamics on the NMR spectra is discussed, evidencing the role played by the paramagnetic defects produced in the materials through pyrolysis.

  17. Efficacy of different disinfectant systems on alginate and addition silicone impression materials of Indian and international origin: a comparative evaluation.

    PubMed

    Samra, R K; Bhide, S V

    2010-09-01

    Study was planned to evaluate the efficacy of commonly used disinfectants and to study qualitatively and quantitatively the persistence of microflora on the untreated (control group) and the disinfected impression surface after 24 h. Disinfectant systems used were immersion systems like glutaraldehyde, sodium hypochlorite and the ultraviolet chamber. The effect of disinfectant on most commonly used Indian impression materials was carried out in this study and results compared with the most commonly used foreign brands for irreversible hydrocolloid and addition silicone. Impressions were made of 25 healthy volunteers. These were disinfected and incubated in an incubator for 24 h at 37°C for aerobic organisms. The inoculation in nutrient media was done to test the viability of microorganisms that can persist after rinsing and disinfection of the impression surface. The colony forming units were counted and compared with that of control group. Control group of all the impression material samples showed growth of Streptococcus viridans, Diphtheroids, Streptococcus pneumoniae to a greater extent. The growth of Candida albicans, Pseudomonas aerugenosa and Staphyloccus albus was present in all the groups but to a lesser extent. The persistence of the microflora on the impression surface of both the studied brands was similar but the concentration of organisms in the alginate control group was two folds as compared to addition silicone group. Use of ultraviolet chamber gave better results compared to the studied immersion systems. All the disinfection systems were effective in reducing the microbial load with ultraviolet chamber as the most effective.

  18. 15th Workshop on Crystalline Silicon Solar Cells and Modules: Materials and Processes; Extended Abstracts and Papers

    SciTech Connect

    Sopori, B. L.

    2005-11-01

    The National Center for Photovoltaics sponsored the 15th Workshop on Crystalline Silicon Solar Cells & Modules: Materials and Processes, held in Vail, CO, August 7-10, 2005. This meeting provided a forum for an informal exchange of technical and scientific information between international researchers in the photovoltaic and relevant non-photovoltaic fields. The workshop addressed the fundamental properties of PV silicon, new solar cell designs, and advanced solar cell processing techniques. A combination of oral presentations by invited speakers, poster sessions, and discussion sessions reviewed recent advances in crystal growth, new cell designs, new processes and process characterization techniques, and cell fabrication approaches suitable for future manufacturing demands. The theme of this year's meeting was 'Providing the Scientific Basis for Industrial Success.' Specific sessions during the workshop included: Advances in crystal growth and material issues; Impurities and defects in Si; Advanced processing; High-efficiency Si solar cells; Thin Si solar cells; and Cell design for efficiency and reliability module operation. The topic for the Rump Session was ''Si Feedstock: The Show Stopper'' and featured a panel discussion by representatives from various PV companies.

  19. Microdistribution of oxygen in silicon

    NASA Technical Reports Server (NTRS)

    Murgai, A.; Chi, J. Y.; Gatos, H. C.

    1980-01-01

    The microdistribution of oxygen in Czochralskii-grown, p-type silicon crystals was determined by using the SEM in the EBIC mode in conjunction with spreading resistance measurements. When the conductivity remained p-type, bands of contrast were observed in the EBIC image which corresponded to maxima in resistivity. When at the oxygen concentration maxima the oxygen donor concentration exceeded the p-type dopant concentration, an inversion of the conductivity occurred. It resulted in the formation of p-n junctions in a striated configuration and the local inversion of the EBIC image contrast. By heat-treating silicon at 1000 C prior to the activation of oxygen donors, some silicon-oxygen micro-precipitates were observed in the EBIC image within the striated oxygen concentration maxima.

  20. Grafting Poly(3-hexylthiophene) from Silicon Nanocrystal Surfaces: Synthesis and Properties of a Functional Hybrid Material with Direct Interfacial Contact.

    PubMed

    Islam, Muhammad Amirul; Purkait, Tapas K; Mobarok, Md Hosnay; Hoehlein, Ignaz M D; Sinelnikov, Regina; Iqbal, Muhammad; Azulay, Doron; Balberg, Isaac; Millo, Oded; Rieger, Bernhard; Veinot, Jonathan G C

    2016-06-20

    Hybrid functional materials (HFMs) comprised of semiconductor nanoparticles and conjugated polymers offer the potential of synergetic photophysical properties. We have developed HFMs based upon silicon nanocrystals (SiNCs) and the conductive polymer poly(3-hexylthiophene) (SiNC@P3HT) by applying surface-initiated Kumada catalyst transfer polycondensation (SI-KCTP). One unique characteristic of the developed SiNC@P3HT is the formation of a direct covalent bonding between SiNCs and P3HT. The presented method for obtaining direct interfacial attachment, which is not accessible using other methods, may allow for the development of materials with efficient electronic communication at the donor-acceptor interfaces. Systematic characterization provides evidence of a core-shell structure, enhanced interfacial electron and/or energy transfer between the P3HT and SiNC components, as well as formation of a type-II heterostructure.

  1. Mechanical Properties of Silicone Rubber Acoustic Lens Material Doped with Fine Zinc Oxide Powders for Ultrasonic Medical Probe

    NASA Astrophysics Data System (ADS)

    Yamamoto, Noriko; Yohachi; Yamashita; Itsumi, Kazuhiro

    2009-07-01

    The mechanical properties of high-temperature-vulcanization silicone (Q) rubber doped with zinc oxide (ZnO) fine powders have been investigated to develop an acoustic lens material with high reliability. The ZnO-doped Q rubber with an acoustic impedance (Z) of 1.46×106 kg·m-2·s-1 showed a tear strength of 43 N/mm and an elongation of 560%. These mechanical property values were about 3 times higher than those of conventional acoustic Q lens materials. The ZnO-doped Q rubbers also showed a lower abrasion loss. These superior characteristics are attributable to the microstructure with fewer origins of breaks; few pores and spherical fine ZnO powder. The high mechanical properties of ZnO-doped Q rubber acoustic lenses enable higher performance during long-life and safe operation during diagnosis using medical array probe applications.

  2. Modeling the mechanical and aging properties of silicone rubber and foam - stockpile-historical & additively manufactured materials

    SciTech Connect

    Maiti, A.; Weisgraber, T. H.; Gee, R. H.

    2014-09-30

    M97* and M9763 belong to the M97xx series of cellular silicone materials that have been deployed as stress cushions in some of the LLNL systems. Their purpose of these support foams is to distribute the stress between adjacent components, maintain relative positioning of various components, and mitigate the effects of component size variation due to manufacturing and temperature changes. In service these materials are subjected to a continuous compressive strain over long periods of time. In order to ensure their effectiveness, it is important to understand how their mechanical properties change over time. The properties we are primarily concerned about are: compression set, load retention, and stress-strain response (modulus).

  3. Fullerene C{sub 70} as a p-type donor in organic photovoltaic cells

    SciTech Connect

    Zhuang, Taojun; Wang, Xiao-Feng E-mail: zrhong@ucla.edu Sano, Takeshi; Kido, Junji E-mail: zrhong@ucla.edu; Hong, Ziruo E-mail: zrhong@ucla.edu; Li, Gang; Yang, Yang

    2014-09-01

    Fullerenes and their derivatives have been widely used as n-type materials in organic transistor and photovoltaic devices. Though it is believed that they shall be ambipolar in nature, there have been few direct experimental proofs for that. In this work, fullerene C{sub 70}, known as an efficient acceptor, has been employed as a p-type electron donor in conjunction with 1,4,5,8,9,11-hexaazatriphenylene hexacarbonitrile as an electron acceptor in planar-heterojunction (PHJ) organic photovoltaic (OPV) cells. High fill factors (FFs) of more than 0.70 were reliably achieved with the C{sub 70} layer even up to 100 nm thick in PHJ cells, suggesting the superior potential of fullerene C{sub 70} as the p-type donor in comparison to other conventional donor materials. The optimal efficiency of these unconventional PHJ cells was 2.83% with a short-circuit current of 5.33 mA/cm{sup 2}, an open circuit voltage of 0.72 V, and a FF of 0.74. The results in this work unveil the potential of fullerene materials as donors in OPV devices, and provide alternative approaches towards future OPV applications.

  4. Development and evaluation of die materials for use in the growth of silicon ribbons by the inverted ribbon growth process, task 2, LSSA project

    NASA Technical Reports Server (NTRS)

    Duffy, M. T.; Berkman, S.; Cullen, G. W.; Moss, H. I.

    1977-01-01

    Silicon sessile drop experiments were performed on a variety of commercially available refractory carbides, nitrides, oxides, and borides to examine the potential of these materials for applications involving either direct contact with molten silicon or as substrates for CVD coatings in the fabrication of dies and crucibles for containing molten silicon. Simultaneous experiments were also conducted with CVD layers of SiC, Si3N4, and SiOxNy. Silicon nitride layers, deposited with NH3:SiH4 ratios ranging from 100:1 down to 5:1, were examined in sessile drop experiments to determine if the layers are degraded as a result of using lower reagent ratios. Preliminary experiments were undertaken on the stability of CVD Si3N4 near the melting point of silicon. Silicon ribbon segments were grown from vitreous carbon dies which had been coated with CVD Si3N4. Depending upon the purity of the die materials, ribbon resistivity values up to 40 Omega cm were obtained.

  5. Surface modification of silicone medical materials by plasma-based ion implantation

    NASA Astrophysics Data System (ADS)

    Kobayashi, Tomohiro; Yokota, Toshihiko; Kato, Rui; Suzuki, Yoshiaki; Iwaki, Masaya; Terai, Takayuki; Takahashi, Noriyoshi; Miyasato, Tomonori; Ujiie, Hiroshi

    2007-04-01

    Silicone (polydimethylsiloxane) sheets and tubes for medical use were irradiated with inert gas ions using plasma-based ion implantation (PBII). The affinity of the surface with tissue examined by an animal test was improved by the irradiation at optimal conditions. The cell attachment percentage increased at an applied voltage of less than -7.5 kV; however, it decreased at higher voltage. The specimens irradiated at higher voltages were more hydrophobic than unirradiated specimens. The surface became rough with increasing voltage and textures, and small domains appeared. This effect was caused by different etching speeds in the amorphous and crystalline areas.

  6. Electronic processes in uniaxially stressed p-type germanium

    SciTech Connect

    Dubon, O.D. Jr.

    1996-02-01

    Effect of uniaxial stress on acceptor-related electronic processes in Ge single crystals doped with Ga, Be, and Cu were studied by Hall and photo-Hall effect measurements in conjunction with infrared spectroscopy. Stress dependence of hole lifetime in p-type Ge single crystals is used as a test for competing models of non-radiative capture of holes by acceptors. Photo-Hall effect shows that hole lifetime in Ga- and Be-doped Ge increases by over one order of magnitude with uniaxial stress at liq. He temps. Photo-Hall of Ge:Be shows a stress-induced change in the temperature dependence of hole lifetime. This is consistent with observed increase of responsivity of Ge:Ga detectors with uniaxial stress. Electronic properties of Ge:Cu are shown to change dramatically with uniaxial stress; the results provide a first explanation for the performance of uniaxially stressed, Cu-diffused Ge:Ga detectors which display a high conductivity in absence of photon signal and therefore have poor sensitivity.

  7. (Ga,Fe)Sb: A p-type ferromagnetic semiconductor

    SciTech Connect

    Tu, Nguyen Thanh; Anh, Le Duc; Tanaka, Masaaki; Hai, Pham Nam

    2014-09-29

    A p-type ferromagnetic semiconductor (Ga{sub 1−x},Fe{sub x})Sb (x = 3.9%–13.7%) has been grown by low-temperature molecular beam epitaxy (MBE) on GaAs(001) substrates. Reflection high energy electron diffraction patterns during the MBE growth and X-ray diffraction spectra indicate that (Ga,Fe)Sb layers have the zinc-blende crystal structure without any other crystallographic phase of precipitates. Magnetic circular dichroism (MCD) spectroscopy characterizations indicate that (Ga,Fe)Sb has the zinc-blende band structure with spin-splitting induced by s,p-d exchange interactions. The magnetic field dependence of the MCD intensity and anomalous Hall resistance of (Ga,Fe)Sb show clear hysteresis, demonstrating the presence of ferromagnetic order. The Curie temperature (T{sub C}) increases with increasing x and reaches 140 K at x = 13.7%. The crystal structure analyses, magneto-transport, and magneto-optical properties indicate that (Ga,Fe)Sb is an intrinsic ferromagnetic semiconductor.

  8. Greyscale proton beam writing in p-type Gallium Arsenide

    NASA Astrophysics Data System (ADS)

    Diering, D.; Spemann, D.; Lenzner, J.; Müller, St.; Böntgen, T.; von Wenckstern, H.

    2013-07-01

    Proton beam writing (PBW) is a well known method for micromachining, e.g. of semiconductors. Up to now, only few indication is given on how the resulting structure height in micromachined semiconductors can be controlled by means of fluence variation. This approach for 3D-microstructuring, called Greyscale PBW, was already successfully demonstrated for negative photoresists. In this study (1 0 0) p-type Gallium Arsenide (GaAs) was irradiated with 2.28 MeV protons and fluences in the range from 1.2×1014 H+ cm-2 to 1.0×1018 H+ cm-2 at the ion beam laboratory LIPSION and subsequently electrochemically etched with 10%-KOH. A linear dependency of structure height on ion fluence was established. In this way, pyramid-like structures as well as concave-shaped structures could be created. GaAs showed a lateral anisotropic etch behaviour during the development step with preferential etching along the [0 1 1] directions. On some structures the surface roughness and the change of conductivity were investigated by atomic force and scanning capacitance microscopy, respectively. The rms roughness of the surface of the structures was 5.4 nm and 10.6 nm for a fluence of 7.8×1015 H+ cm-2 and 1.2×1017 H+ cm-2, respectively. We observed an increasing etching rate for fluences larger than 1016 H+ cm-2.

  9. Preparation and Characterization of Ophthalmic Lens Materials Containing Titanium Silicon Oxide and Silver Nanoparticles.

    PubMed

    No, Jung-Won; Kim, Dong-Hyun; Lee, Min-Jae; Kim, Duck-Hyun; Kim, Tae-Hun; Sung, A-Young

    2015-10-01

    Hydrogel ophthalmic lenses containing fluorine-substituted aniline group, titanium silicon oxide nartoparticles, and silver nanoparticles were copolymerized, and the physical and optical properties of the hydrogel lenses were measured. To produce the hydrophilic ophthalmic lenses, the additives were added to the mixture containing HEMA, NVP, MA, EGDMA, and AIBN. The cast mold method was used for the manufacture of the hydrogel ophthalmic lenses, and the produced lenses were completely soaked in a 0.9% NaCl normal saline solution for 24 hours for hydration. The physical properties of the produced macromolecule showed that the water content was 32.5-37.6%, the refractive index was 1.450-1.464, the UV-B transmittance was 0.5-35.2%, and the contact angle was between 56 and 69°. Also, the addition of aniline, titanium silicon oxide, and silver nanoparticles allowed the ophthalmic lenses to block UV. These results show that the produced macromolecule can be used as hydrophilic lenses for ophthalmologic purposes that can block UV. PMID:26726456

  10. Materials preparation and fabrication of pyroelectric polymer/silicon MOSFET detector arrays. Final report

    SciTech Connect

    Bloomfield, P.

    1992-03-27

    The authors have delivered several 64-element linear arrays of pyroelectric elements fully integrated on silicon wafers with MOS readout devices. They have delivered detailed drawings of the linear arrays to LANL. They have processed a series of two inch wafers per submitted design. Each two inch wafer contains two 64 element arrays. After spin-coating copolymer onto the arrays, vacuum depositing the top electrodes, and polarizing the copolymer films so as to make them pyroelectrically active, each wafer was split in half. The authors developed a thicker oxide coating separating the extended gate electrode (beneath the polymer detector) from the silicon. This should reduce its parasitic capacitance and hence improve the S/N. They provided LANL three processed 64 element sensor arrays. Each array was affixed to a connector panel and selected solder pads of the common ground, the common source voltage supply connections, the 64 individual drain connections, and the 64 drain connections (for direct pyroelectric sensing response rather than the MOSFET action) were wire bonded to the connector panel solder pads. This entails (64 + 64 + 1 + 1) = 130 possible bond connections per 64 element array. This report now details the processing steps and the progress of the individual wafers as they were carried through from beginning to end.

  11. Silicon Materials Task of the Low Cost Solar Array Project, Phase 3. Effect of Impurities and Processing on Silicon Solar Cells

    NASA Technical Reports Server (NTRS)

    Hopkins, R. H.; Davis, J. R.; Blais, P. D.; Rohatgi, A.; Campbell, R. B.; Rai-Choudhury, P.; Stapleton, R. E.; Mollenkopf, H. C.; Mccormick, J. R.

    1979-01-01

    The effects of impurities, various thermochemical processes, and any impurity process interactions on the performance of terrestrial silicon solar cells are defined. Determinations of the segregation coefficients of tungsten, tantalum, and cobalt for the Czochralski pulling of silicon single crystals are reported. Sensitive neutron activation analysis was used to determine the metal impurity content of the silicon while atomic absorption was used to measure the metal content of the residual liquid from which the doped crystals were grown. Gettering of Ti doped silicon wafers improved cell performance by one to two percent for the highest temperatures and longest times. The HCl is more effective than POCl3 treatments for deactivating Ti but POCl3 and HCl produced essentially identical results for Mo or Fe.

  12. Silicon materials task of the low cost solar array project. Phase 3: Effect of impurities and processing on silicon solar cells

    NASA Technical Reports Server (NTRS)

    Hopkins, R. H.; Davis, J. R.; Blais, P. D.; Rohatgi, A.; Campbell, R. B.; Rai-Choudhury, P.; Mollenkopf, H. C.; Mccormick, J. R.

    1979-01-01

    The 13th quarterly report of a study entitled an Investigation of the Effects of Impurities and Processing on Silicon Solar Cells is given. The objective of the program is to define the effects of impurities, various thermochemical processes and any impurity-process interactions on the performance of terrestrial silicon solar cells. The Phase 3 program effort falls in five areas: (1) cell processing studies; (2) completion of the data base and impurity-performance modeling for n-base cells; (3) extension of p-base studies to include contaminants likely to be introduced during silicon production, refining or crystal growth; (4) anisotropy effects; and (5) a preliminary study of the permanence of impurity effects in silicon solar cells. The quarterly activities for this report focus on tasks (1), (3) and (4).

  13. The role of silicon on the bioactivity of Skelite(TM) bioceramic: A material and biological characterization of silicon alpha-tricalcium phosphate based ceramics

    NASA Astrophysics Data System (ADS)

    Pietak, Alexis Mari

    Skelite(TM) bioceramics are novel synthetic skeletal replacement materials that participate in the full remodeling process of bone. Skelite contains a high fraction of Silicon Stabilized alpha-Tricalcium Phosphate (Si-TCP), a novel phase to which the unique bioactive properties of Skelite have been attributed. The role of Si in the development of the microporous, interconnected microstructure and mixed phase composition of Skelite was investigated using crystallization kinetics and defect characterization studies. The kinetics of the phase transformation to Si-TCP were studied using rapid thermal processing of thin films on quartz substrates. The results, interpreted using a novel Avrami model, show that Si acts as a nucleation agent for Si-TCP, and also that Si pins the microstructure of the films at higher concentrations. Characterization of defects induced by Si substitution into the phases of Skelite material utilized electron spin resonance (ESR) and thermoluminescence (TL) techniques. These results identify two unique paramagnetic defect centers associated with Si substitution in the hydroxyapatite lattice. Quantification of the relative level of these centers supports a novel chemical model that describes the development of the mixed phase system of Skelite as a function of silica addition. The significance of the Si-TCP phase, sample morphology, and surface chemistry on the activity of osteoclast and osteoblast cells was investigated using cell culture and protein functionalized atomic force microscopy techniques. The biological characterization identifies three interaction mechanisms between Skelite and the biological system. Skelite releases a soluble molecular complex containing Si to the extracellular media, which has a significant bioactive effect on osteoclast and osteoblast growth and activity. Using protein functionalized atomic force microscopy the surface chemistry and reactivity of samples is shown to influence osteopontin affinity for Skelite

  14. Electrical creation of spin polarization in silicon at room temperature

    NASA Astrophysics Data System (ADS)

    Jansen, Ron

    2010-03-01

    The integration of magnetism and mainstream semiconductor electronics could impact information technology in ways beyond imagination. A pivotal step is the implementation of spin-based electronic functionality in silicon devices. Much of the interest in silicon derives from its prevalence in semiconductor technology and from the robustness and longevity of spin as it is only weakly coupled to other degrees of freedom in the material. Recently it has become possible to induce and detect spin polarization in otherwise non-magnetic semiconductors (GaAs and Si) using all-electrical structures, but so far at temperatures below 150 K and only in n-type material. The main challenges are: (i) to design fully electrical silicon-based spintronic devices with large spin signals, (ii) to demonstrate device operation at room temperature, (iii) to do so for n-type and p-type material, and (iv) to find ways to manipulate spins and spin flow with a gate electric field. After a brief overview of the state of affairs, our recent advances in these areas are described. In particular, we demonstrate room-temperature electrical injection of spin polarization into n-type and p-type silicon from a ferromagnetic tunnel contact, spin manipulation using the Hanle effect, and the electrical detection of the induced spin accumulation. It is shown that a spin splitting as large as 2.9 meV can be created in Si at room temperature, corresponding to an electron spin polarization of 4.6%. The results open the way to the implementation of spin functionality in complementary silicon devices and electronic circuits operating at ambient temperature, and to the exploration of their prospects as well as the fundamental rules that govern their behavior. [4pt] [1] S.P. Dash, S. Sharma, R.S. Patel, M.P. de Jong and R. Jansen, Nature 462, 491 (2009).

  15. A silicon nanowire-reduced graphene oxide composite as a high-performance lithium ion battery anode material.

    PubMed

    Ren, Jian-Guo; Wang, Chundong; Wu, Qi-Hui; Liu, Xiang; Yang, Yang; He, Lifang; Zhang, Wenjun

    2014-03-21

    Toward the increasing demands of portable energy storage and electric vehicle applications, silicon has been emerging as a promising anode material for lithium-ion batteries (LIBs) owing to its high specific capacity. However, serious pulverization of bulk silicon during cycling limits its cycle life. Herein, we report a novel hierarchical Si nanowire (Si NW)-reduced graphene oxide (rGO) composite fabricated using a solvothermal method followed by a chemical vapor deposition process. In the composite, the uniform-sized [111]-oriented Si NWs are well dispersed on the rGO surface and in between rGO sheets. The flexible rGO enables us to maintain the structural integrity and to provide a continuous conductive network of the electrode, which results in over 100 cycles serving as an anode in half cells at a high lithium storage capacity of 2300 mA h g(-1). Due to its [111] growth direction and the large contact area with rGO, the Si NWs in the composite show substantially enhanced reaction kinetics compared with other Si NWs or Si particles.

  16. Characterization of Amorphous Silicon Advanced Materials and PV Devices: Final Technical Report, 15 December 2001--31 January 2005

    SciTech Connect

    Taylor, P. C.

    2005-11-01

    The major objectives of this subcontract have been: (1) understand the microscopic properties of the defects that contribute to the Staebler-Wronski effect to eliminate this effect, (2) perform correlated studies on films and devices made by novel techniques, especially those with promise to improve stability or deposition rates, (3) understand the structural, electronic, and optical properties of films of hydrogenated amorphous silicon (a-Si:H) made on the boundary between the amorphous and microcrystalline phases, (4) search for more stable intrinsic layers of a-Si:H, (5) characterize the important defects, impurities, and metastabilities in the bulk and at surfaces and interfaces in a-Si:H films and devices and in important alloy systems, and (6) make state-of-the-art plasma-enhanced chemical vapor deposition (PECVD) devices out of new, advanced materials, when appropriate. All of these goals are highly relevant to improving photovoltaic devices based on a-Si:H and related alloys. With regard to the first objective, we have identified a paired hydrogen site that may be the defect that stabilizes the silicon dangling bonds formed in the Staebler-Wronski effect.

  17. Impurity Resonant States p-type Doping in Wide-Band-Gap Nitrides.

    PubMed

    Liu, Zhiqiang; Yi, Xiaoyan; Yu, Zhiguo; Yuan, Gongdong; Liu, Yang; Wang, Junxi; Li, Jinmin; Lu, Na; Ferguson, Ian; Zhang, Yong

    2016-01-01

    In this work, a new strategy for achieving efficient p-type doping in high bandgap nitride semiconductors to overcome the fundamental issue of high activation energy has been proposed and investigated theoretically, and demonstrated experimentally. Specifically, in an AlxGa(1-x)N/GaN superlattice structure, by modulation doping of Mg in the AlxGa(1-x)N barriers, high concentration of holes are generated throughout the material. A hole concentration as high as 1.1 × 10(18) cm(-3) has been achieved, which is about one order of magnitude higher than that typically achievable by direct doping GaN. Results from first-principle calculations indicate that the coupling and hybridization between Mg 2p impurity and the host N 2p orbitals are main reasons for the generation of resonant states in the GaN wells, which further results in the high hole concentration. We expect this approach to be equally applicable for other high bandgap materials where efficient p-type doing is difficult. Furthermore, a two-carrier-species Hall-effect model is proposed to delineate and discriminate the characteristics of the bulk and 2D hole, which usually coexist in superlattice-like doping systems. The model reported here can also be used to explain the abnormal freeze-in effect observed in many previous reports. PMID:26777294

  18. Impurity Resonant States p-type Doping in Wide-Band-Gap Nitrides

    PubMed Central

    Liu, Zhiqiang; Yi, Xiaoyan; Yu, Zhiguo; Yuan, Gongdong; Liu, Yang; Wang, Junxi; Li, Jinmin; Lu, Na; Ferguson, Ian; Zhang, Yong

    2016-01-01

    In this work, a new strategy for achieving efficient p-type doping in high bandgap nitride semiconductors to overcome the fundamental issue of high activation energy has been proposed and investigated theoretically, and demonstrated experimentally. Specifically, in an AlxGa1−xN/GaN superlattice structure, by modulation doping of Mg in the AlxGa1−xN barriers, high concentration of holes are generated throughout the material. A hole concentration as high as 1.1 × 1018 cm−3 has been achieved, which is about one order of magnitude higher than that typically achievable by direct doping GaN. Results from first-principle calculations indicate that the coupling and hybridization between Mg 2p impurity and the host N 2p orbitals are main reasons for the generation of resonant states in the GaN wells, which further results in the high hole concentration. We expect this approach to be equally applicable for other high bandgap materials where efficient p-type doing is difficult. Furthermore, a two-carrier-species Hall-effect model is proposed to delineate and discriminate the characteristics of the bulk and 2D hole, which usually coexist in superlattice-like doping systems. The model reported here can also be used to explain the abnormal freeze-in effect observed in many previous reports. PMID:26777294

  19. Impurity Resonant States p-type Doping in Wide-Band-Gap Nitrides

    NASA Astrophysics Data System (ADS)

    Liu, Zhiqiang; Yi, Xiaoyan; Yu, Zhiguo; Yuan, Gongdong; Liu, Yang; Wang, Junxi; Li, Jinmin; Lu, Na; Ferguson, Ian; Zhang, Yong

    2016-01-01

    In this work, a new strategy for achieving efficient p-type doping in high bandgap nitride semiconductors to overcome the fundamental issue of high activation energy has been proposed and investigated theoretically, and demonstrated experimentally. Specifically, in an AlxGa1-xN/GaN superlattice structure, by modulation doping of Mg in the AlxGa1-xN barriers, high concentration of holes are generated throughout the material. A hole concentration as high as 1.1 × 1018 cm-3 has been achieved, which is about one order of magnitude higher than that typically achievable by direct doping GaN. Results from first-principle calculations indicate that the coupling and hybridization between Mg 2p impurity and the host N 2p orbitals are main reasons for the generation of resonant states in the GaN wells, which further results in the high hole concentration. We expect this approach to be equally applicable for other high bandgap materials where efficient p-type doing is difficult. Furthermore, a two-carrier-species Hall-effect model is proposed to delineate and discriminate the characteristics of the bulk and 2D hole, which usually coexist in superlattice-like doping systems. The model reported here can also be used to explain the abnormal freeze-in effect observed in many previous reports.

  20. Membrane Targeting of P-type ATPases in Plant Cells

    SciTech Connect

    Jeffrey F. Harper, Ph.D.

    2004-06-30

    How membrane proteins are targeted to specific subcellular locations is a very complex and poorly understood area of research. Our long-term goal is to use P-type ATPases (ion pumps), in a model plant system Arabidopsis, as a paradigm to understand how members of a family of closely related membrane proteins can be targeted to different subcellular locations. The research is divided into two specific aims. The first aim is focused on determining the targeting destination of all 10 ACA-type calcium pumps (Arabidopsis Calcium ATPase) in Arabidopsis. ACAs represent a plant specific-subfamily of plasma membrane-type calcium pumps. In contrast to animals, the plant homologs have been found in multiple membrane systems, including the ER (ACA2), tonoplast (ACA4) and plasma membrane (ACA8). Their high degree of similarity provides a unique opportunity to use a comparative approach to delineate the membrane specific targeting information for each pump. One hypothesis to be tested is that an endomembrane located ACA can be re-directed to the plasma membrane by including targeting information from a plasma membrane isoform, ACA8. Our approach is to engineer domain swaps between pumps and monitor the targeting of chimeric proteins in plant cells using a Green Fluorescence Protein (GFP) as a tag. The second aim is to test the hypothesis that heterologous transporters can be engineered into plants and targeted to the plasma membrane by fusing them to a plasma membrane proton pump. As a test case we are evaluating the targeting properties of fusions made between a yeast sodium/proton exchanger (Sod2) and a proton pump (AHA2). This fusion may potentially lead to a new strategy for engineering salt resistant plants. Together these aims are designed to provide fundamental insights into the biogenesis and function of plant cell membrane systems.

  1. Research of materials for porous matrices in sol-gel systems based on silicon dioxide and metallic oxides

    NASA Astrophysics Data System (ADS)

    Maraeva, E. V.; Bobkov, A. A.; Maximov, A. I.; Moshnikov, V. A.; Nalimova, S. S.

    2015-11-01

    In this study silicon dioxide - stannic oxide and silicon dioxide - zinc nanomaterials oxide were obtained through sol-gel technology. The results of nitrogen thermal desorption measurements, atomic force microscopy measurements and particle sizes measurements are discussed.

  2. Processing of n+/p-/p+ strip detectors with atomic layer deposition (ALD) grown Al2O3 field insulator on magnetic Czochralski silicon (MCz-si) substrates

    NASA Astrophysics Data System (ADS)

    Härkönen, J.; Tuovinen, E.; Luukka, P.; Gädda, A.; Mäenpää, T.; Tuominen, E.; Arsenovich, T.; Junkes, A.; Wu, X.; Li, Z.

    2016-08-01

    Detectors manufactured on p-type silicon material are known to have significant advantages in very harsh radiation environment over n-type detectors, traditionally used in High Energy Physics experiments for particle tracking. In p-type (n+ segmentation on p substrate) position-sensitive strip detectors, however, the fixed oxide charge in the silicon dioxide is positive and, thus, causes electron accumulation at the Si/SiO2 interface. As a result, unless appropriate interstrip isolation is applied, the n-type strips are short-circuited. Widely adopted methods to terminate surface electron accumulation are segmented p-stop or p-spray field implantations. A different approach to overcome the near-surface electron accumulation at the interface of silicon dioxide and p-type silicon is to deposit a thin film field insulator with negative oxide charge. We have processed silicon strip detectors on p-type Magnetic Czochralski silicon (MCz-Si) substrates with aluminum oxide (Al2O3) thin film insulator, grown with Atomic Layer Deposition (ALD) method. The electrical characterization by current-voltage and capacitance-voltage measurement shows reliable performance of the aluminum oxide. The final proof of concept was obtained at the test beam with 200 GeV/c muons. For the non-irradiated detector the charge collection efficiency (CCE) was nearly 100% with a signal-to-noise ratio (S/N) of about 40, whereas for the 2×1015 neq/cm2 proton irradiated detector the CCE was 35%, when the sensor was biased at 500 V. These results are comparable with the results from p-type detectors with the p-spray and p-stop interstrip isolation techniques. In addition, interestingly, when the aluminum oxide was irradiated with Co-60 gamma-rays, an accumulation of negative fixed oxide charge in the oxide was observed.

  3. Strengthening of oxidation resistant materials for gas turbine applications. [treatment of silicon ceramics for increased flexural strength and impact resistance

    NASA Technical Reports Server (NTRS)

    Kirchner, H. P.

    1974-01-01

    Silicon nitride and silicon carbide ceramics were treated to form compressive surface layers. On the silicon carbide, quenching and thermal exposure treatments were used, and on the silicon nitride, quenching, carburizing, and a combination of quenching and carburizing were used. In some cases substantial improvements in impact resistance and/or flexural strength were observed. The presence of compressive surface stresses was demonstrated by slotted rod tests.

  4. Hierarchically porous silicon-carbon-nitrogen hybrid materials towards highly efficient and selective adsorption of organic dyes

    NASA Astrophysics Data System (ADS)

    Meng, Lala; Zhang, Xiaofei; Tang, Yusheng; Su, Kehe; Kong, Jie

    2015-01-01

    The hierarchically macro/micro-porous silicon-carbon-nitrogen (Si-C-N) hybrid material was presented with novel functionalities of totally selective and highly efficient adsorption for organic dyes. The hybrid material was conveniently generated by the pyrolysis of commercial polysilazane precursors using polydivinylbenzene microspheres as sacrificial templates. Owing to the Van der Waals force between sp-hybridized carbon domains and triphenyl structure of dyes, and electrostatic interaction between dyes and Si-C-N matrix, it exhibites high adsorption capacity and good regeneration and recycling ability for the dyes with triphenyl structure, such as methyl blue (MB), acid fuchsin (AF), basic fuchsin and malachite green. The adsorption process is determined by both surface adsorption and intraparticle diffusion. According to the Langmuir model, the adsorption capacity is 1327.7 mg.g-1 and 1084.5 mg.g-1 for MB and AF, respectively, which is much higher than that of many other adsorbents. On the contrary, the hybrid materials do not adsorb the dyes with azo benzene structures, such as methyl orange, methyl red and congro red. Thus, the hierarchically porous Si-C-N hybrid material from a facile and low cost polymer-derived strategy provides a new perspective and possesses a significant potential in the treatment of wastewater with complex organic pollutants.

  5. Hierarchically porous silicon-carbon-nitrogen hybrid materials towards highly efficient and selective adsorption of organic dyes.

    PubMed

    Meng, Lala; Zhang, Xiaofei; Tang, Yusheng; Su, Kehe; Kong, Jie

    2015-01-01

    The hierarchically macro/micro-porous silicon-carbon-nitrogen (Si-C-N) hybrid material was presented with novel functionalities of totally selective and highly efficient adsorption for organic dyes. The hybrid material was conveniently generated by the pyrolysis of commercial polysilazane precursors using polydivinylbenzene microspheres as sacrificial templates. Owing to the Van der Waals force between sp-hybridized carbon domains and triphenyl structure of dyes, and electrostatic interaction between dyes and Si-C-N matrix, it exhibites high adsorption capacity and good regeneration and recycling ability for the dyes with triphenyl structure, such as methyl blue (MB), acid fuchsin (AF), basic fuchsin and malachite green. The adsorption process is determined by both surface adsorption and intraparticle diffusion. According to the Langmuir model, the adsorption capacity is 1327.7 mg·g(-1) and 1084.5 mg·g(-1) for MB and AF, respectively, which is much higher than that of many other adsorbents. On the contrary, the hybrid materials do not adsorb the dyes with azo benzene structures, such as methyl orange, methyl red and congro red. Thus, the hierarchically porous Si-C-N hybrid material from a facile and low cost polymer-derived strategy provides a new perspective and possesses a significant potential in the treatment of wastewater with complex organic pollutants. PMID:25604334

  6. Perovskite Sr-doped LaCrO3 as a new p-type transparent conducting oxide

    SciTech Connect

    Zhang, Hongliang; Du, Yingge; Papadogianni, Alexandra; Bierwagen, Oliver; Sallis, Shawn; Piper, Louis F. J.; Bowden, Mark E.; Shutthanandan, V.; Sushko, Petr; Chambers, Scott A.

    2015-09-16

    Transparent conducting oxides (TCOs) constitute a unique class of materials which combine the seemingly mutually exclusive properties of electrical conductivity and optical transparency in a single material. TCOs are useful for a wide range of applications including solar cells, displays, light emitting diodes and transparent electronics. Simple post-transition metal oxides such as ZnO, In2O3 and SnO2 are wide gap insulators in which the ionic character generates an oxygen 2p-derived valence band (VB) and a metal s-derived conduction band (CB), resulting in large optical band gaps (>3.0 eV) and excellent n-type conductivity when donor doped. In contrast, the development of efficient p-type TCOs remains a global materials challenge. Converting n-type oxides to p-type analogs by acceptor doping is extremely difficult and these materials display poor conductivity.

  7. Eighth workshop on crystalline silicon solar cell materials and processes: Extended abstracts and papers

    SciTech Connect

    1998-08-01

    The theme of this workshop is Supporting the Transition to World Class Manufacturing. This workshop provides a forum for an informal exchange of information between researchers in the photovoltaic and non-photovoltaic fields on various aspects of impurities and defects in silicon, their dynamics during device processing, and their application in defect engineering. This interaction helps establish a knowledge base that can be used for improving device fabrication processes to enhance solar-cell performance and reduce cell costs. It also provides an excellent opportunity for researchers from industry and universities to recognize mutual needs for future joint research. The workshop format features invited review presentations, panel discussions, and two poster sessions. The poster sessions create an opportunity for both university and industrial researchers to present their latest results and provide a natural forum for extended discussions and technical exchanges.

  8. Material properties of silicon carbide fibers with continuously applied sol-gel alumina coatings. Master's thesis

    SciTech Connect

    Daehnick, C.C.

    1990-12-01

    An investigation was conducted to determine the effect of non-alpha-alumina coatings applied under varying conditions on some of the properties of silicon carbide fibers. Limited characterization of the coating by optical, scanning electron, and transmitted electron microscopy as well as energy-dispersive x-ray analysis was performed. Tensile tests were used to determine changes in elastic modulus, ultimate strength, and strain to failure of the coated fibers relative to uncoated fibers. The coatings were found to lower the mean value of the measured properties as their thickness increased, but the measurements were not accurate enough to determine if this corresponded to a simple rule of mixtures relationship or not. For the same reason, no definitive statements can be made about the properties of the coating itself. A two-dimensional plane-strain analysis incorporating thermal residual stresses was also performed to determined possible failure points.

  9. Determination of aluminum and silicon in biological materials by inductively coupled plasma atomic emission spectrometry with electrothermal vaporization

    NASA Astrophysics Data System (ADS)

    Matusiewicz, Henryk; Barnes, Ramon M.

    An atomic emission spectrometric method is described for the determination of trace elements in microvolume samples especially of biological materials. Based upon the arrangement of a commercial electrothermal vaporizer and a 40-MHz inductively coupled plasma, the direct determination of aluminum and silicon in human body fluids such as urine and serum and aluminum in hemodialysis solution is performed. The instrumental system involves vaporizing the sample from a modified graphite electrode followed by atomization and excitation of the vapors in the ICP discharge. Compromise experimental conditions are reported and calibration functions compared. Limits of detection in 5-μl samples were 8 pg Al and 2.5 ng Si, and after preconcentration of Al with a poly(acrylamidoxime) resin, the detection limit was 1 pg Al. Recovery of 5 μg Si/ml and 10 ng Al/ml from aqueous and synthetic standards was 80-85% and 96-103%, respectively.

  10. Measurement of material parameters that limit the open-circuit voltage in P-N-junction silicon solar cells

    NASA Technical Reports Server (NTRS)

    Lindholm, F. A.; Neugroschel, A.; Sah, C. T.

    1977-01-01

    The greatest gains in solar energy conversion efficiency of p-n-junction silicon solar cells come from increasing the open-circuit voltage V sub OC; it is important to understand and characterize the material parameters that limit the V sub OC. Strong experimental evidence exists to support the assertion that either an anomalously large minority carrier charge storage or an anomalously small minority carrier lifetime in the quasi-neutral emitter region limits the open circuit voltage. A method is presented for measuring charge storage and effective lifetime. Static and transient measurements are analyzed using physical models of the solar cell characteristics. This analysis yields the emitter charge storage and life-time, which then can be related to the various physical mechanisms, such as energy band gap shrinkage, that have been proposed earlier as responsible for limiting V sub OC.

  11. Preparation and properties of flexible flame-retardant neutron shielding material based on methyl vinyl silicone rubber

    NASA Astrophysics Data System (ADS)

    Chai, Hao; Tang, Xiaobin; Ni, Minxuan; Chen, Feida; Zhang, Yun; Chen, Da; Qiu, Yunlong

    2015-09-01

    Flexible flame-retardant composites were prepared using high-functional methyl vinyl silicone rubber matrix with B4C, hollow beads, and zinc borate (ZB) as filler materials. As filler content increased, the tensile strength, elongation, and tear strength of the composites initially increased and then decreased. The shore hardness of the composites increased with increasing filler content with a maximum value of 30 HA. The heat insulation properties of the composites with hollow beads were higher than that of the ordinary composites with the same filler mass fraction. When ZB content exceeded 12 wt%, the limit of oxygen index of the composites was higher than 27.1%. With Am-Be neutron as the test radiation source, the transmission of neutron for a 2 cm sample was only 47.8%. Powder surface modification improved the mechanical properties, thermal conductivity, flame retardancy, and neutron shielding performance of the composites, but did not affect shore hardness.

  12. 16th Workshop on Crystalline Silicon Solar Cells and Modules: Materials and Processes; Program, Extended Abstracts, and Papers

    SciTech Connect

    Sopori, B. L.

    2006-08-01

    The National Center for Photovoltaics sponsored the 16th Workshop on Crystalline Silicon Solar Cells and Modules: Materials and Processes held August 6-9, 2006 in Denver, Colorado. The workshop addressed the fundamental properties of PV-Si, new solar cell designs, and advanced solar cell processing techniques. It provided a forum for an informal exchange of technical and scientific information between international researchers in the photovoltaic and relevant non-photovoltaic fields. The Workshop Theme was: "Getting more (Watts) for Less ($i)". A combination of oral presentations by invited speakers, poster sessions, and discussion sessions reviewed recent advances in crystal growth, new cell structures, new processes and process characterization techniques, and cell fabrication approaches suitable for future manufacturing demands. The special sessions included: Feedstock Issues: Si Refining and Purification; Metal-impurity Engineering; Thin Film Si; and Diagnostic Techniques.

  13. Influence of Cooling Hole Geometry and Material Conductivity on the Thermal Response of Cooled Silicon Nitride Plate

    NASA Technical Reports Server (NTRS)

    Abdul-Aziz, Ali; Bhatt, Ramakrishna T.; Girgis, Morris

    2002-01-01

    To complement the effectiveness of ceramic materials and the applicability to turbine engine applications, a parametric study using the finite element method was carried out. This study conducted thorough analyses of a thermal-barrier-coated silicon nitride (Si3N4) plate specimen with cooling channels, where its thermal conductivity was verified in an attempt to minimize the thermal stresses and reach an optimal rate of stress. The thermal stress profile was generated for specimens with circular and square cooling channels. Lower stresses were reported for a higher magnitude of thermal conductivity and in particular for the circular cooling channel arrangement. Contour plots for the stresses and the temperature are presented and discussed.

  14. Silicon as a virtual plasmonic material: Acquisition of its transient optical constants and the ultrafast surface plasmon-polariton excitation

    NASA Astrophysics Data System (ADS)

    Danilov, P. A.; Ionin, A. A.; Kudryashov, S. I.; Makarov, S. V.; Rudenko, A. A.; Saltuganov, P. N.; Seleznev, L. V.; Yurovskikh, V. I.; Zayarny, D. A.; Apostolova, T.

    2015-06-01

    Ultrafast intense photoexcitation of a silicon surface is complementarily studied experimentally and theoretically, with its prompt optical dielectric function obtained by means of time-resolved optical reflection microscopy and the underlying electron-hole plasma dynamics modeled numerically, using a quantum kinetic approach. The corresponding transient surface plasmon-polariton (SPP) dispersion curves of the photo-excited material were simulated as a function of the electron-hole plasma density, using the derived optical dielectric function model, and directly mapped at several laser photon energies, measuring spatial periods of the corresponding SPP-mediated surface relief nanogratings. The unusual spectral dynamics of the surface plasmon resonance, initially increasing with the increase in the electron-hole plasma density but damped at high interband absorption losses induced by the high-density electron-hole plasma through instantaneous bandgap renormalization, was envisioned through the multi-color mapping.

  15. Silicon as a virtual plasmonic material: Acquisition of its transient optical constants and the ultrafast surface plasmon-polariton excitation

    SciTech Connect

    Danilov, P. A.; Ionin, A. A.; Kudryashov, S. I. Makarov, S. V.; Rudenko, A. A.; Saltuganov, P. N.; Seleznev, L. V.; Yurovskikh, V. I.; Zayarny, D. A.; Apostolova, T.

    2015-06-15

    Ultrafast intense photoexcitation of a silicon surface is complementarily studied experimentally and theoretically, with its prompt optical dielectric function obtained by means of time-resolved optical reflection microscopy and the underlying electron-hole plasma dynamics modeled numerically, using a quantum kinetic approach. The corresponding transient surface plasmon-polariton (SPP) dispersion curves of the photo-excited material were simulated as a function of the electron-hole plasma density, using the derived optical dielectric function model, and directly mapped at several laser photon energies, measuring spatial periods of the corresponding SPP-mediated surface relief nanogratings. The unusual spectral dynamics of the surface plasmon resonance, initially increasing with the increase in the electron-hole plasma density but damped at high interband absorption losses induced by the high-density electron-hole plasma through instantaneous bandgap renormalization, was envisioned through the multi-color mapping.

  16. Orientation Effects in Ballistic High-Strained P-type Si Nanowire FETs.

    PubMed

    Zhang, Jia-Hong; Huang, Qing-An; Yu, Hong; Lei, Shuang-Ying

    2009-01-01

    In order to design and optimize high-sensitivity silicon nanowire-field-effect transistor (SiNW FET) pressure sensors, this paper investigates the effects of channel orientations and the uniaxial stress on the ballistic hole transport properties of a strongly quantized SiNW FET placed near the high stress regions of the pressure sensors. A discrete stress-dependent six-band k.p method is used for subband structure calculation, coupled to a two-dimensional Poisson solver for electrostatics. A semi-classical ballistic FET model is then used to evaluate the ballistic current-voltage characteristics of SiNW FETs with and without strain. Our results presented here indicate that [110] is the optimum orientation for the p-type SiNW FETs and sensors. For the ultra-scaled 2.2 nm square SiNW, due to the limit of strong quantum confinement, the effect of the uniaxial stress on the magnitude of ballistic drive current is too small to be considered, except for the [100] orientation. However, for larger 5 nm square SiNW transistors with various transport orientations, the uniaxial tensile stress obviously alters the ballistic performance, while the uniaxial compressive stress slightly changes the ballistic hole current. Furthermore, the competition of injection velocity and carrier density related to the effective hole masses is found to play a critical role in determining the performance of the nanotransistors.

  17. Orientation Effects in Ballistic High-Strained P-type Si Nanowire FETs.

    PubMed

    Zhang, Jia-Hong; Huang, Qing-An; Yu, Hong; Lei, Shuang-Ying

    2009-01-01

    In order to design and optimize high-sensitivity silicon nanowire-field-effect transistor (SiNW FET) pressure sensors, this paper investigates the effects of channel orientations and the uniaxial stress on the ballistic hole transport properties of a strongly quantized SiNW FET placed near the high stress regions of the pressure sensors. A discrete stress-dependent six-band k.p method is used for subband structure calculation, coupled to a two-dimensional Poisson solver for electrostatics. A semi-classical ballistic FET model is then used to evaluate the ballistic current-voltage characteristics of SiNW FETs with and without strain. Our results presented here indicate that [110] is the optimum orientation for the p-type SiNW FETs and sensors. For the ultra-scaled 2.2 nm square SiNW, due to the limit of strong quantum confinement, the effect of the uniaxial stress on the magnitude of ballistic drive current is too small to be considered, except for the [100] orientation. However, for larger 5 nm square SiNW transistors with various transport orientations, the uniaxial tensile stress obviously alters the ballistic performance, while the uniaxial compressive stress slightly changes the ballistic hole current. Furthermore, the competition of injection velocity and carrier density related to the effective hole masses is found to play a critical role in determining the performance of the nanotransistors. PMID:22574043

  18. Flat-plate solar array project process development area, process research of non-CZ silicon material

    NASA Technical Reports Server (NTRS)

    Campbell, R. B.

    1984-01-01

    The program is designed to investigate the fabrication of solar cells on N-type base material by a simultaneous diffusion of N-type and P-type dopants to form an P(+)NN(+) structure. The results of simultaneous diffusion experiments are being compared to cells fabricated using sequential diffusion of dopants into N-base material in the same resistivity range. The process used for the fabrication of the simultaneously diffused P(+)NN(+) cells follows the standard Westinghouse baseline sequence for P-base material except that the two diffusion processes (boron and phosphorus) are replaced by a single diffusion step. All experiments are carried out on N-type dendritic web grown in the Westinghouse pre-pilot facility. The resistivities vary from 0.5 (UC OMEGA)cm to 5 (UC OMEGA)cm. The dopant sources used for both the simultaneous and sequential diffusion experiments are commercial metallorganic solutions with phosphorus or boron components. After these liquids are applied to the web surface, they are baked to form a hard glass which acts as a diffusion source at elevated temperatures. In experiments performed thus far, cells produced in sequential diffusion tests have properties essentially equal to the baseline N(+)PP(+) cells. However, the simultaneous diffusions have produced cells with much lower IV characteristics mainly due to cross-doping of the sources at the diffusion temperature. This cross-doping is due to the high vapor pressure phosphorus (applied as a metallorganic to the back surface) diffusion through the SiO2 mask and then acting as a diffusant source for the front surface.

  19. Efficacy of different disinfectant systems on alginate and addition silicone impression materials of Indian and international origin: a comparative evaluation.

    PubMed

    Samra, R K; Bhide, S V

    2010-09-01

    Study was planned to evaluate the efficacy of commonly used disinfectants and to study qualitatively and quantitatively the persistence of microflora on the untreated (control group) and the disinfected impression surface after 24 h. Disinfectant systems used were immersion systems like glutaraldehyde, sodium hypochlorite and the ultraviolet chamber. The effect of disinfectant on most commonly used Indian impression materials was carried out in this study and results compared with the most commonly used foreign brands for irreversible hydrocolloid and addition silicone. Impressions were made of 25 healthy volunteers. These were disinfected and incubated in an incubator for 24 h at 37°C for aerobic organisms. The inoculation in nutrient media was done to test the viability of microorganisms that can persist after rinsing and disinfection of the impression surface. The colony forming units were counted and compared with that of control group. Control group of all the impression material samples showed growth of Streptococcus viridans, Diphtheroids, Streptococcus pneumoniae to a greater extent. The growth of Candida albicans, Pseudomonas aerugenosa and Staphyloccus albus was present in all the groups but to a lesser extent. The persistence of the microflora on the impression surface of both the studied brands was similar but the concentration of organisms in the alginate control group was two folds as compared to addition silicone group. Use of ultraviolet chamber gave better results compared to the studied immersion systems. All the disinfection systems were effective in reducing the microbial load with ultraviolet chamber as the most effective. PMID:21886411

  20. Picosecond intersubband hole relaxation in p-type quantum wells

    SciTech Connect

    Xu, Z.; Fauchet, P.M.; Rella, C.W.; Schwettman, H.A.

    1995-12-31

    We report the first direct measurement of the relaxation time of holes in p-type quantum wells using tunable, subpicosecond mid-infrared laser pulses in a pump-probe arrangement. The QW layers consisted of 50 In{sub 0.5}Ga{sub 0.5}As/Al{sub 0.5}Ga{sub 0.5}As periods. The In{sub 0.5}Ga{sub 0.5}As well was 4 nm wide and the Al{sub 0.5}Ga{sub 0.5}As barrier was 8 nm wide. The dopant concentration was 10{sup 19} CM{sup -3} which corresponds to a sheet density of 1.2 x 10{sup 13} CM{sup -2}. The room temperature IR spectrum showed a 50 meV wide absorption peak at 5.25 {mu}m (220 meV). This energy agrees with the calculated n=1 heavy hole to n=1 light hole transition energy of 240 meV (150 meV for strain and 90 meV for confinement). The large absorption width results from hole-hole scattering and the difference in dispersion relations between the two subbands. The equal-wavelength pump-probe transmission measurements were performed using the Stanford free electron laser (FEL). The FEL pulses were tuned between 4 and 6 {mu} m and their duration was less than 1 ps. The measurements were performed as a function of temperature, pump wavelength and intensity (from 0.3 to 10 GW/cm{sup 2}). In all our experiments, we find an increase of transmission (decrease of absorption or bleaching) following photopumping, which recovers as a single exponential with a time constant (relaxation time) of the order of 1 picosecond. The maximum change in transmission is linear with pump 2 intensity below 1 GW/cm{sup 2} and saturates to {approximately}3% with a saturation intensity I{sub sat} of 3 GW/cm{sup 2}. As the saturation regime is entered, the relaxation time increases from 0.8 ps to 1.8 ps. This relaxation time depends on the temperature T: it increases from 0.8 ps to 1.3 ps as T decreases from 300 K to 77 K. Finally, when we tune the laser through the absorption band, the magnitude of the signal changes but its temporal behavior does not change, within the accuracy of the measurements.

  1. New photovoltaic devices based on the sensitization of p-type semiconductors: challenges and opportunities.

    PubMed

    Odobel, Fabrice; Le Pleux, Loïc; Pellegrin, Yann; Blart, Errol

    2010-08-17

    Because solar energy is the most abundant renewable energy resource, the clear connection between human activity and global warming has strengthened the interest in photovoltaic science. Dye-sensitized solar cells (DSSCs) provide a promising low-cost technology for harnessing this energy source. Until recently, much of the research surrounding DSSCs had been focused on the sensitization of n-type semiconductors, such as titanium dioxide (Gratzel cells). In an n-type dye-sensitized solar cell (n-DSSC), an electron is injected into the conduction band of an n-type semiconductor (n-SC) from the excited state of the sensitizer. Comparatively few studies have examined the sensitization of wide bandgap p-type semiconductors. In a p-type DSSC (p-DSSC), the photoexcited sensitizer is reductively quenched by hole injection into the valence band of a p-type semiconductor (p-SC). The study of p-DSSCs is important both to understand the factors that control the rate of hole photoinjection and to aid the rational design of efficient p-DSSCs. In theory, p-DSSCs should be able to work as efficiently as n-DSSCs. In addition, this research provides a method for preparing tandem DSSCs consisting of a TiO(2)-photosensitized anode and a photosensitized p-type SC as a cathode. Tandem DSSCs are particularly important because they represent low-cost photovoltaic devices whose photoconversion efficiencies could exceed 15%. This Account describes recent research results on p-DSSCs. Because these photoelectrochemical devices are the mirror images of conventional n-DSSCs, they share some structural similarities, but they use different materials and have different charge transfer kinetics. In this technology, nickel oxide is the predominant p-SC material used, but much higher photoconversion efficiencies could be achieved with new p-SCs materials with deeper valence band potential. Currently, iodide/triiodide is the main redox mediator of electron transport within these devices, but we expect

  2. Evaluation available encapsulation materials for low-cost long-life silicon photovoltaic arrays

    NASA Technical Reports Server (NTRS)

    Carmichael, D. C.; Gaines, G. B.; Noel, G. T.; Sliemers, F. A.; Nance, G. P.; Bunk, A. R.; Brockway, M. C.

    1978-01-01

    Experimental evaluation of selected encapsulation designs and materials based on an earlier study which have potential for use in low cost, long-life photovoltaic arrays are reported. The performance of candidate materials and encapsulated cells were evaluated principally for three types of encapsulation designs based on their potentially low materials and processing costs: (1) polymeric coatings, transparent conformal coatings over the cell with a structural-support substrate; (2) polymeric film lamination, cells laminated between two films or sheets of polymeric materials; and (3) glass-covered systems, cells adhesively bonded to a glass cover (superstrate) with a polymeric pottant and a glass or other substrate material. Several other design types, including those utilizing polymer sheet and pottant materials, were also included in the investigation.

  3. Electron and proton damage coefficients in low-resistivity silicon

    NASA Technical Reports Server (NTRS)

    Srour, J. R.; Othmer, S.; Chiu, K. Y.

    1975-01-01

    The electron and proton damage coefficients for low resistivity p-type boron-doped silicon were determined from minority-carrier lifetime measurements on bulk material and diffusion length measurements on solar cells. The bulk samples were irradiated with electrons at three energy levels (0.5, 1.5, and 2.5 MeV) using a Dynamitron. Lifetime measurements were made with a steady-state photoconductivity apparatus, and comparison measurements of diffusion length were obtained using the steady-state surface photovoltage method (Goodman, 1961). The diffusion-length damage coefficients increased with decreasing resistivity for boron-doped silicon; this dependence can be qualitatively accounted for using a two-level Hall-Shockley-Read model. The damage coefficients for solar cells were larger than for their bulk-material counterparts. The damage coefficient was apparently independent of the dislocation density in the 0.1 ohm-cm bulk samples and solar cells investigated.

  4. CROSS-DISCIPLINARY PHYSICS AND RELATED AREAS OF SCIENCE AND TECHNOLOGY: Excellent Passivation of p-Type Si Surface by Sol-Gel Al2O3 Films

    NASA Astrophysics Data System (ADS)

    Xiao, Hai-Qing; Zhou, Chun-Lan; Cao, Xiao-Ning; Wang, Wen-Jing; Zhao, Lei; Li, Hai-Ling; Diao, Hong-Wei

    2009-08-01

    Al2O3 films with a thickness of about 100 nm synthesized by spin coating and thermally treated are applied for field-induced surface passivation of p-type crystalline silicon. The level of surface passivation is determined by techniques based on photoconductance. An effective surface recombination velocity below 100 cm/s is obtained on 10Ω ·cm p-type c-Si wafers (Cz Si). A high density of negative fixed charges in the order of 1012 cm-2 is detected in the Al2O3 films and its impact on the level of surface passivation is demonstrated experimentally. Furthermore, a comparison between the surface passivation achieved for thermal SiO2 and plasma enhanced chemical vapor deposition SiNx:H films on the same c-Si is presented. The high negative fixed charge density explains the excellent passivation of p-type c-Si by Al2O3.

  5. NbFeSb based p-type half-Heusler for power generation applications

    NASA Astrophysics Data System (ADS)

    Joshi, Giri; He, Ran; Engber, Michael; Samsonidze, Georgy; Pantha, Tej; Dahal, Ekraj; Dahal, Keshab; Yang, Jian; Lan, Yucheng; Kozinsky, Boris; Ren, Zhifeng

    2015-03-01

    We report a peak dimensionless figure-of-merit (ZT) of ~1 at 700 oC in nanostructured p-type Nb0.6Ti0.4FeSb0.95Sn0.05composition. Even though the power factor of the Nb0.6Ti0.4FeSb0.95Sn0.05 composition is improved by 25% in comparison to the previously reported p-type Hf0.44Zr0.44Ti0.12CoSb0.8Sn0.2, the ZT value is not increased due to a higher thermal conductivity. However, the higher power factor of the Nb0.6Ti0.4FeSb0.95Sn0.05 composition led to a 15% increase in power output of a thermoelectric device in comparison to a device made from the previous best material Hf0.44Zr0.44Ti0.12CoSb0.8Sn0.2. The n-type material used to make the unicouple device is the best reported nanostructured Hf0.25Zr0.75NiSn0.99Sb0.01 composition with the lowest hafnium (Hf) content. Both the p- and n-type nanostructured samples are prepared by ball milling the arc melted ingot and hot pressing the finely ground powders. Moreover, the raw material cost of the Nb0.6Ti0.4FeSb0.95Sn0.05 composition is more than six times lower compared to the cost of the previous best p-type Hf0.44Zr0.44Ti0.12CoSb0.8Sn0.2. This cost reduction is crucial for these materials to be used in large-scale quantities for vehicle and industrial waste heat recovery applications. DOE:DE-EE0004840.

  6. A molecular method to assess bioburden embedded within silicon-based resins used on modern spacecraft materials

    NASA Astrophysics Data System (ADS)

    Stam, Christina N.; Bruckner, James; Spry, J. Andy; Venkateswaran, Kasthuri; La Duc, Myron T.

    2012-07-01

    Current assessments of bioburden embedded in spacecraft materials are based on work performed in the Viking era (1970s), and the ability to culture organisms extracted from such materials. To circumvent the limitations of such approaches, DNA-based techniques were evaluated alongside established culturing techniques to determine the recovery and survival of bacterial spores encapsulated in spacecraft-qualified polymer materials. Varying concentrations of Bacillus pumilus SAFR-032 spores were completely embedded in silicone epoxy. An organic dimethylacetamide-based solvent was used to digest the epoxy and spore recovery was evaluated via gyrB-targeted qPCR, direct agar plating, most probably number analysis, and microscopy. Although full-strength solvent was shown to inhibit the germination and/or outgrowth of spores, dilution in excess of 100-fold allowed recovery with no significant decrease in cultivability. Similarly, qPCR (quantitative PCR) detection sensitivities as low as ~103 CFU ml-1 were achieved upon removal of inhibitory substances associated with the epoxy and/or solvent. These detection and enumeration methods show promise for use in assessing the embedded bioburden of spacecraft hardware.

  7. Low cost solar array project silicon materials task. Development of a process for high capacity arc heater production of silicon for solar arrays

    NASA Technical Reports Server (NTRS)

    Reed, W. H.

    1978-01-01

    Silicon tetrachloride and a reductant (sodium) will be injected into an arc heated mixture of hydrogen and argon, yielding silicon and gaseous sodium chloride. Detailed characterization of the Sonicore sodium injection nozzle, using water as the test fluid was completed. Results indicated that flow rates of 45 gph sodium and 50 scfm argon should produce sufficiently small droplet sizes. The design effort was also completed for the test system preparation which was divided into two categories: (1) system components and (2) test system-laboratory integration.

  8. Modeling of thin, back-wall silicon solar cells

    NASA Technical Reports Server (NTRS)

    Baraona, C. R.

    1979-01-01

    The performance of silicon solar cells with p-n junctions on the nonilluminated surface (i.e., upside-down or back-wall cells) was calculated. These structures consisted of a uniformly shaped p-type substrate layer, a p(+)-type field layer on the front (illuminated) surface, and a shallow, n-type junction on the back (nonilluminated) surface. A four-layer solar cell model was used to calculate efficiency, open-circuit voltage, and short-circuit current. The effect on performance of p-layer thickness and resistivity was determined. The diffusion length was varied to simulate the effect of radiation damage. The results show that peak initial efficiencies greater than 15 percent are possible for cell thicknesses or 100 micrometers or less. After 10 years of radiation damage in geosynchronous orbit, thin (25 to 50 micrometers thick) cells made from 10 to 100 ohm cm material show the smallest decrease (approximately 10 percent) in performance.

  9. Structural and Thermoelectric Properties of Polycrystalline p-Type Mg2- x Li x Si

    NASA Astrophysics Data System (ADS)

    Nieroda, P.; Kolezynski, A.; Oszajca, M.; Milczarek, J.; Wojciechowski, K. T.

    2016-07-01

    The aim of this study was to determine the location of Li atoms in Mg2Si structure, and verify the influence of Li dopant on the transport properties of obtained thermoelectric materials. The results of theoretical studies of the electronic band structure (full potential linearized augmented plane wave method) in Li-doped Mg2Si are presented. Theoretical calculations indicate that only in the case when Li is located in the Mg position, the samples will have p-type conduction. To confirm the theoretical predictions, a series of samples with nominal composition Mg2- x Li x Si ( x = 0-0.5) were prepared using the spark plasma sintering (SPS) method. Structural and phase composition analyses were carried out by x-ray and neutron powder diffraction, as well as scanning electron microscopy. Neutron diffraction studies confirmed that the lithium atoms substitute magnesium in the Mg2Si structure. The investigations of the influence of Li dopant on the transport properties, i.e. electrical conductivity, the Seebeck coefficient and the thermal conductivity, were carried out in a temperature range from 340 K to 720 K. Carrier concentration was measured with Hall method. The positive values of the Seebeck coefficient and Hall coefficient indicate that all examined samples show p-type conductivity. On the basis of the experimental data, the temperature dependencies of the thermoelectric figure of merit ZT were calculated.

  10. p-Type polymer-hybridized high-performance piezoelectric nanogenerators.

    PubMed

    Lee, Keun Young; Kumar, Brijesh; Seo, Ju-Seok; Kim, Kwon-Ho; Sohn, Jung Inn; Cha, Seung Nam; Choi, Dukhyun; Wang, Zhong Lin; Kim, Sang-Woo

    2012-04-11

    Enhancing the output power of a nanogenerator is essential in applications as a sustainable power source for wireless sensors and microelectronics. We report here a novel approach that greatly enhances piezoelectric power generation by introducing a p-type polymer layer on a piezoelectric semiconducting thin film. Holes at the film surface greatly reduce the piezoelectric potential screening effect caused by free electrons in a piezoelectric semiconducting material. Furthermore, additional carriers from a conducting polymer and a shift in the Fermi level help in increasing the power output. Poly(3-hexylthiophene) (P3HT) was used as a p-type polymer on piezoelectric semiconducting zinc oxide (ZnO) thin film, and phenyl-C(61)-butyric acid methyl ester (PCBM) was added to P3HT to improve carrier transport. The ZnO/P3HT:PCBM-assembled piezoelectric power generator demonstrated 18-fold enhancement in the output voltage and tripled the current, relative to a power generator with ZnO only at a strain of 0.068%. The overall output power density exceeded 0.88 W/cm(3), and the average power conversion efficiency was up to 18%. This high power generation enabled red, green, and blue light-emitting diodes to turn on after only tens of times bending the generator. This approach offers a breakthrough in realizing a high-performance flexible piezoelectric energy harvester for self-powered electronics. PMID:22409420

  11. Silicon Nitride for Direct Water-Splitting and Corrosion Mitigation

    SciTech Connect

    Head, J.; Turner, J.A.

    2006-01-01

    Todays fossil fuels are becoming harder to obtain, creating pollution problems, and posing hazards to people’s health. One alternative to fossil fuels is hydrogen, capable of serving as a clean and efficient energy carrier. Certain semiconductors are able to harness the energy of photons and direct it into water electrolysis in a process known as photoelectrochemical water splitting. Triple junction devices integrate three semiconductors of different band gaps resulting in a monolithic material that absorbs over a broader spectrum. Amorphous silicon (a-Si) is one such material that, when stacked in tandem, possesses water-splitting capabilities. Even though a-Si is capable of splitting water, it is an unstable material in solution and therefore requires a coating to protect the surface from corrosion. A stable, transparent material that has the potential for corrosion protection is silicon nitride. In this study, silicon nitride thin films were grown using DC magnetron sputtering with varying amounts of argon and nitrogen added to the system. X-ray diffraction indicated amorphous silicon nitride films. Current as a function of potential was determined from cyclic voltammetry measurements. Mott-Schottky analysis showed n-type behavior with absorption and transmission measurements indicated variation in flatband potentials. Variation in band gap values ranging from 1.90 to 4.0 eV. Corrosion measurements reveal that the silicon nitride samples exhibit both p-type and n-type behavior. Photocurrent over a range of potentials was greater in samples that were submerged in acidic electrolyte. Silicon nitride shows good stability in acidic, neutral, and basic solutions, indicative of a good material for corrosion mitigation.

  12. Surface toughness of silicon nitride bioceramics: II, Comparison with commercial oxide materials.

    PubMed

    McEntire, Bryan J; Enomoto, Yuto; Zhu, Wenliang; Boffelli, Marco; Marin, Elia; Pezzotti, Giuseppe

    2016-02-01

    Raman microprobe-assisted indentation, a micromechanics method validated in a companion paper, was used to compare the surface toughening behaviors of silicon nitride (Si3N4) and alumina-based bioceramics employed in joint arthroplasty (i.e., monolithic alumina, Al2O3, and yttria-stabilized zirconia (ZrO2)-toughened alumina, ZTA). Quantitative assessments of microscopic stress fields both ahead and behind the tip of Vickers indentation cracks propagated under increasing indentation loads were systematically made using a Raman microprobe with spatial resolution on the order of a single micrometer. Concurrently, crack opening displacement (COD) profiles were monitored on the same microcracks screened by Raman spectroscopy. The Raman eye clearly visualized different mechanisms operative in toughening Si3N4 and ZTA bioceramics (i.e., crack-face bridging and ZrO2 polymorphic transformation, respectively) as compared to the brittle behavior of monolithic Al2O3. Moreover, emphasis was placed on assessing not only the effectiveness but also the durability of such toughening effects when the biomaterials were aged in a hydrothermal environment. A significant degree of embrittlement at the biomaterial surface was recorded in the transformation-toughened ZTA, with the surface toughness reduced by exposure to the hydrothermal environment. Conversely, the Si3N4 biomaterial experienced a surface toughness value independent of hydrothermal attack. Crack-face bridging thus appears to be a durable surface toughening mechanism for biomaterials in joint arthroplasty. PMID:26437609

  13. Role of atomic layer deposited aluminum oxide as oxidation barrier for silicon based materials

    SciTech Connect

    Fiorentino, Giuseppe Morana, Bruno; Forte, Salvatore; Sarro, Pasqualina Maria

    2015-01-15

    In this paper, the authors study the protective effect against oxidation of a thin layer of atomic layer deposited (ALD) aluminum oxide (Al{sub 2}O{sub 3}). Nitrogen doped silicon carbide (poly-SiC:N) based microheaters coated with ALD Al{sub 2}O{sub 3} are used as test structure to investigate the barrier effect of the alumina layers to oxygen and water vapor at very high temperature (up to 1000 °C). Different device sets have been fabricated changing the doping levels, to evaluate possible interaction between the dopants and the alumina layer. The as-deposited alumina layer morphology has been evaluated by means of AFM analysis and compared to an annealed sample (8 h at 1000 °C) to estimate the change in the grain structure and the film density. The coated microheaters are subjected to very long oxidation time in dry and wet environment (up to 8 h at 900 and 1000 °C). By evaluating the electrical resistance variation between uncoated reference devices and the ALD coated devices, the oxide growth on the SiC is estimated. The results show that the ALD alumina coating completely prevents the oxidation of the SiC up to 900 °C in wet environment, while an oxide thickness reduction of 50% is observed at 1000 °C compared to uncoated devices.

  14. Influence of Containment on the Growth of Silicon-Germanium (ICESAGE): A Materials Science Investigation

    NASA Technical Reports Server (NTRS)

    Volz, M. P.; Mazuruk, K.; Croll, A.

    2014-01-01

    A series of Ge Si crystal growth experiments are planned to be conducted in the Low 1-x x Gradient Furnace (LGF) onboard the International Space Station. The primary objective of the research is to determine the influence of containment on the processing-induced defects and impurity incorporation in germanium-silicon alloy crystals. A comparison will be made between crystals grown by the normal and "detached" Bridgman methods and the ground-based float zone technique. Crystals grown without being in contact with a container have superior quality to otherwise similar crystals grown in direct contact with a container, especially with respect to impurity incorporation, formation of dislocations, and residual stress in crystals. "Detached" or "dewetted" Bridgman growth is similar to regular Bridgman growth in that most of the melt is in contact with the crucible wall, but the crystal is separated from the wall by a small gap, typically of the order of 10-100 microns. Long duration reduced gravity is essential to test the proposed theory of detached growth. Detached growth requires the establishment of a meniscus between the crystal and the ampoule wall. The existence of this meniscus depends on the ratio of the strength of gravity to capillary forces. On Earth, this ratio is large and stable detached growth can only be obtained over limited conditions. Crystals grown detached on the ground exhibited superior structural quality as evidenced by measurements of etch pit density, synchrotron white beam X-ray topography and double axis X-ray diffraction.

  15. Conductivity of materials made of aluminum nitride and silicon nitride mixtures

    NASA Technical Reports Server (NTRS)

    Gorbatov, A. G.; Kamyshov, V. M.

    1978-01-01

    To establish the possible mechanism for conductivity in aluminum nitride a study was made of the electric conductivity of pure AlN and its mixtures with silicon nitride at different temperatures and partial pressures of nitrogen in the gas phase. The thermoelectromotive force was also measured. The experiments used polycrystalline samples of cylindrical shape 18 mm in diameter made of powders by hot pressing in graphite press molds at a temperature of 1973-2273 K and pressure 1,470,000 n/sqm. The items obtained by this method had porosity not over 5%. After pressing, the samples were machined to remove carbon from the surface, and were annealed in a stream of dry ammonia for 10 h at a temperature of 1273-1373 K. Electric conductivity was measured according to the bridge scheme on an alternating current of frequency 10 kHz. In order to guarantee close contact of the platinum electrodes with the surface of the samples, a thin layer of platinum was sprayed on them. Experiments were conducted in the temperature interval 1273-1573 K with a half hour delay at each assigned temperature with heating and cooling.

  16. In vitro uptake and release studies of ocular pharmaceutical agents by silicon-containing and p-HEMA hydrogel contact lens materials.

    PubMed

    Karlgard, C C S; Wong, N S; Jones, L W; Moresoli, C

    2003-05-12

    The in vitro uptake and release behaviour of cromolyn sodium, ketotifen fumarate, ketorolac tromethamine and dexamethasone sodium phosphate with silicon-containing (lotrafilcon and balafilcon) and p-HEMA-containing (etafilcon, alphafilcon, polymacon, vifilcon and omafilcon) hydrogel contact lenses indicated that both drug and material affected the uptake and release behaviour. Rapid uptake and release (within 50 min) was observed for all drugs except ketotifen fumarate which was more gradual taking approximately 5h. Furthermore, the maximum uptake differed significantly between drugs and materials. The highest average uptake (7879+/-684 microg/lens) was cromolyn sodium and the lowest average uptake (67+/-13 microg/lens) was dexamethasone sodium phosphate. Partial release of the drug taken up was observed for all drugs except dexamethasone sodium phosphate where no release was detected. Sustained release was demonstrated only by ketotifen fumarate. Drug uptake/release appeared to be a function of lens material ionicity, water and silicon content. The silicon-containing materials released less drug than the p-HEMA-containing materials. The lotrafilcon material demonstrated less interactions with the drugs than the balafilcon material which can be explained by their different bulk composition and surface treatment. PMID:12711169

  17. The effect of carbon on surface quality of solid-state-sintered silicon carbide as optical materials

    SciTech Connect

    Chen, Jian Huang, Zhengren; Chen, Zhongming; Yuan, Ming; Liu, Yan; Zhu, Yunzhou

    2014-03-01

    The microstructure and the distribution of carbon (C) in silicon carbide (SiC) ceramics were investigated by scanning electron microscopy and transmission electron microscopy. The results show that C can restrain the growth of SiC grains and densify SiC ceramics with the increase of the C content, but residual C introduces a new phase-C to SiC ceramics. The hardness of C is less than that of SiC, so it's difficult to be polished as optical materials. The existence of C phase doesn't lead to the increase of surface roughness on SiC optical materials, but it leads to the decrease of the reflectance of SiC as the optical materials because the optical absorption of C in visible light is stronger than that of SiC. It indicates that C content is very important to the surface properties of SiC, which will affect the coating of chemical vapor deposition SiC or Si on the surface of SiC ceramics because of the different physical and chemical properties between C and SiC. - Highlights: • The microstructure and the distribution of carbon were investigated. • A new phase in the optical materials is introduced. • It is difficult to be polished as the optical materials because of different phases. • Carbon leads to the decrease of reflectance because of its absorption to light wave. • The different properties may affect the coating of chemical vapor deposition on SiC.

  18. Method for making defect-free zone by laser-annealing of doped silicon

    DOEpatents

    Narayan, Jagdish; White, Clark W.; Young, Rosa T.

    1980-01-01

    This invention is a method for improving the electrical properties of silicon semiconductor material. The method comprises irradiating a selected surface layer of the semiconductor material with high-power laser pulses characterized by a special combination of wavelength, energy level, and duration. The combination effects melting of the layer without degrading electrical properties, such as minority-carrier diffusion length. The method is applicable to improving the electrical properties of n- and p-type silicon which is to be doped to form an electrical junction therein. Another important application of the method is the virtually complete removal of doping-induced defects from ion-implanted or diffusion-doped silicon substrates.

  19. Formation of ohmic contact by pre-annealing of shallow nanopores in macroporous silicon and its characterization

    NASA Astrophysics Data System (ADS)

    Maji, S.; Dev Das, R.; Jana, M.; Roychaudhuri, C.; Mondal, N.; Dutta, S. K.; Bandopadhyay, N. R.; Saha, H.

    2010-05-01

    Macroporous silicon is a promising material for wide spectrum of electrical applications ranging from photonic devices, microsystems engineering, supercapacitors to biosensors. Fabrication of good quality ohmic contact on macroporous silicon is a prerequisite for its widespread use in electrical sensor applications but it is also challenging since shallow nanopores are always present within the macropores. This paper aims at the formation of low resistance and fairly ohmic contacts on p-type macroporous silicon with 1.5 μm pore diameter. Electrical contacts formed by vacuum evaporation of aluminium exhibit non-ohmic behaviour owing to the presence of the shallow nanoporous region formed on the surface of crystallites in macroporous silicon. To overcome this problem a controlled pre-annealing step at a temperature of 900 °C for 30 min leading to closure of shallow nanopores through coalescence of nanocrystallites of silicon due to grain growth has been carried out. The growth parameters are computed from the FESEM characteristics of the macroporous silicon preannealed at 900 °C for varying time. For optimally preannealed macroporous silicon the I- V characteristics of macroporous silicon has been found to exhibit fairly ohmic behaviour with vacuum evaporated aluminium. Detailed electrical characterization of vacuum evaporated contacts on both unannealed and preannealed macroporous silicon has been carried out using modified TLM technique. It has been found that the specific contact resistance is almost five times lower for the latter.

  20. Ultraviolet light-emitting diodes with polarization-doped p-type layer

    NASA Astrophysics Data System (ADS)

    Hu, Wenxiao; Qin, Ping; Song, Weidong; Zhang, Chongzhen; Wang, Rupeng; Zhao, Liangliang; Xia, Chao; Yuan, Songyang; Yin, Yian; Li, Shuti

    2016-09-01

    We report ultraviolet light emitting diode (LEDs) with polarization doped p-type layer. Fabricated LEDs with polarization doped p-type layer exhibited reduced forward voltage and enhanced light output power, compared to those with traditional p-type AlGaN layer. The improvement is attributed to improved hole concentration and the smooth valence band by the polarization enhanced p-type doping. Our simulated results reveal that this p-type layer can further enhance the performance of ultraviolet LEDs by removing the electron blocking layer (EBL).