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Sample records for initially p-type silicon

  1. P-type silicon drift detectors

    SciTech Connect

    Walton, J.T.; Krieger, B.; Krofcheck, D.; O`Donnell, R.; Odyniec, G.; Partlan, M.D.; Wang, N.W.

    1995-06-01

    Preliminary results on 16 CM{sup 2}, position-sensitive silicon drift detectors, fabricated for the first time on p-type silicon substrates, are presented. The detectors were designed, fabricated, and tested recently at LBL and show interesting properties which make them attractive for use in future physics experiments. A pulse count rate of approximately 8 {times} l0{sup 6} s{sup {minus}1} is demonstrated by the p-type silicon drift detectors. This count rate estimate is derived by measuring simultaneous tracks produced by a laser and photolithographic mask collimator that generates double tracks separated by 50 {mu}m to 1200 {mu}m. A new method of using ion-implanted polysilicon to produce precise valued bias resistors on the silicon drift detectors is also discussed.

  2. 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.

  3. 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.

  4. p-type silicon detector for brachytherapy dosimetry.

    PubMed

    Piermattei, A; Azario, L; Monaco, G; Soriani, A; Arcovito, G

    1995-06-01

    The sensitivity of a cylindrical p-type silicon detector was studied by means of air and water measurements using different photon beams. A lead filter cap around the diode was used to minimize the dependence of the detector response as a function of the brachytherapy photon energy. The radial dose distribution of a high-activity 192Ir source in a brachytherapy phantom was measured by means of the shielded diode and the agreement of these data with theoretical evaluations confirms the method used to compensate diode response in the intermediate energy range. The diode sensitivity was constant over a wide range of dose rates of clinical interest; this allowed one to have a small detector calibrated in terms of absorbed dose in a medium. Theoretical evaluations showed that a single shielding filter around the p-type diode is sufficient to obtain accurate dosimetry for 192Ir, 137Cs, and 60Co brachytherapy sources.

  5. 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.

  6. Development of improved p-type silicon-germanium alloys

    NASA Technical Reports Server (NTRS)

    Mclane, George; Wood, Charles; Vandersande, Jan; Raag, Valvo; Heshmatpour, Ben

    1987-01-01

    Annealing experiments in the temperature range 1100-1275 C have been performed on p-type Si(0.8)Ge(0.2) samples with BP, B(6.5)P, and GaSb material additives. Both electrical resistivity and Seebeck coefficient generally decrease for these samples as annealing temperature is increased, with thermoelectric power factor sometimes being improved by annealing.

  7. 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.

  8. 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.

  9. Microhardness of carbon-doped (111) p-type Czochralski silicon

    NASA Technical Reports Server (NTRS)

    Danyluk, S.; Lim, D. S.; Kalejs, J.

    1985-01-01

    The effect of carbon on (111) p-type Czochralski silicon is examined. The preparation of the silicon and microhardness test procedures are described, and the equation used to determine microhardness from indentations in the silicon wafers is presented. The results indicate that as the carbon concentration in the silicon increases the microhardness increases. The linear increase in microhardness is the result of carbon hindering dislocation motion, and the effect of temperature on silicon deformation and dislocation mobility is explained. The measured microhardness was compared with an analysis which is based on dislocation pinning by carbon; a good correlation was observed. The Labusch model for the effect of pinning sites on dislocation motion is given.

  10. 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.

  11. Thermal model for breakdown in p-type hydrogenated amorphous silicon films with coplanar electrodes

    NASA Astrophysics Data System (ADS)

    Avila, A.; Asomoza, R.

    2000-09-01

    p-Type glow discharge hydrogenated amorphous silicon films with nearly placed (˜5 μm) coplanar metallic electrodes were led to breakdown under the effect of voltage bias. Non-ohmicity in the I- V plot was analyzed in order to look for the transport mechanism helping to produce breakdown in the films. A thermal model is shown to fit reasonably the electrical behavior of samples prior to breakdown. Two parts are developed in this approximation: the first one assumes that during the initial homogeneous heating of the semiconductor due to Joule effect, stationary states are reached. The heat is assumed to dissipate from the metallic contacts through a Newton's convection mechanism. From the experimental data and the model proposed, the I- V plot is fitted, the heat transfer area and constant are calculated and the temperature-voltage plot is determined. In the second part, the heat conduction equation along the distance between the contacts is numerically solved in one dimension with this information. The result provides an estimate of the time required by the sample to reach a certain steady-state limiting temperature above which much faster heating produces breakdown. This time correlates well to the delay time reported in the literature.

  12. Hole transport through proton-irradiated p-type silicon wafers during electrochemical anodization

    SciTech Connect

    Breese, M. B. H.; Champeaux, F. J. T.; Bettiol, A. A.; Teo, E. J.; Blackwood, D. J.

    2006-01-15

    The hole current density flowing through and around proton-irradiated areas of p-type silicon during electrochemical anodization is simulated and studied experimentally using scanning electron microscopy and photoluminescence imaging. It is shown that for certain irradiation geometries the current flow may be either reduced or enhanced in areas adjacent to irradiated lines, resulting in enhanced or reduced rates of porous silicon formation and corresponding changes in photoluminescence intensity and feature height. The current flow to the surface is unaffected by both the beam straggle and the high defect density at the end of ion range, enabling feature dimensions of {approx}200 nm to be attained. This study has enabled fabrication of micromachined and patterned porous silicon structures in anodized wafers with accurate control of feature dimensions, layer thickness, and photoluminescence emission wavelength and intensity.

  13. Empirical model predicting the layer thickness and porosity of p-type mesoporous silicon

    NASA Astrophysics Data System (ADS)

    Wolter, Sascha J.; Geisler, Dennis; Hensen, Jan; Köntges, Marc; Kajari-Schröder, Sarah; Bahnemann, Detlef W.; Brendel, Rolf

    2017-04-01

    Porous silicon is a promising material for a wide range of applications because of its versatile layer properties and the convenient preparation by electrochemical etching. Nevertheless, the quantitative dependency of the layer thickness and porosity on the etching process parameters is yet unknown. We have developed an empirical model to predict the porosity and layer thickness of p-type mesoporous silicon prepared by electrochemical etching. The impact of the process parameters such as current density, etching time and concentration of hydrogen fluoride is evaluated by ellipsometry. The main influences on the porosity of the porous silicon are the current density, the etching time and their product while the etch rate is dominated by the current density, the concentration of hydrogen fluoride and their product. The developed model predicts the resulting layer properties of a certain porosification process and can, for example be used to enhance the utilization of the employed chemicals.

  14. 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.

  15. Ultrathin polytyramine films by electropolymerisation on highly doped p-type silicon electrodes

    NASA Astrophysics Data System (ADS)

    Losic, Dusan; Cole, Martin; Thissen, Helmut; Voelcker, Nicolas H.

    2005-06-01

    In recent years, silicon-based materials have been used extensively in device fabrication for sensors, microfluidic and biomaterial applications. In order to enhance the performance of the material, a number of surface functionalisations are employed. However, until now, silicon has not been used as an electrode material for electrodeposition of functional polymers. Here, highly doped p-type silicon was used as an electrode facilitating the electropolymerisation of ultrathin polytyramine (PT) films by cyclic voltammetry. The influence of resistivity, pre-treatment of the silicon surface and electrochemical conditions on the electropolymerisation process was studied. The results show that ultrathin PT films with a controlled thickness from 2 to 15 nm exhibit good electrochemical stability in buffer solution (pH 6.8) over a large potential window (-1.5 V to 1.5 V) and passivating properties towards a redox probe. In terms of the film morphology, a pinhole-free smooth surface with a roughness below 0.5 nm and with dominantly globular features of 40-60 nm diameter was observed by AFM. XPS characterisation showed that PT films display amine functional groups at the coating surface. UV induced silicon oxidation was used to prepare patterned PT films.

  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. Lateral photovoltaic effect in p-type silicon induced by surface states

    NASA Astrophysics Data System (ADS)

    Huang, Xu; Mei, Chunlian; Gan, Zhikai; Zhou, Peiqi; Wang, Hui

    2017-03-01

    A colossal lateral photovoltaic effect (LPE) was observed at the surface of p-type silicon, which differs from the conventional thought that a large LPE is only observed in Schottky junctions and PN junctions consisting of several layers with different conductivities. It shows a high sensitivity of 499.24 mV/mm and an ultra-broadband spectral responsivity (from 405 nm to 980 nm) at room temperature, which makes it an attractive candidate for near-infrared detection. We propose that this phenomenon can be understood by considering the surface band bending near the surface of p-Si induced by charged surface states. The energy band diagrams of the samples are shown based on X-ray photoelectron spectroscopy suggesting the correlation between the LPE and surface band bending. The conjectures are validated by changing the surface states of p-type silicon using Ni nano-films. These findings reveal a generation mechanism of the LPE and may lead to p-Si based, broadband-responsivity, low-cost, and high-precision optical and optoelectronic applications.

  18. 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.

  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. Monte Carlo Simulation of Giant Piezoresistance Effect in p-TYPE Silicon Nanostructures

    NASA Astrophysics Data System (ADS)

    Nghiêm, T. T. Trang; Aubry-Fortuna, V.; Chassat, C.; Bosseboeuf, A.; Dollfus, P.

    We present a study of the giant piezoresistance effect in p-type silicon using full-band Monte Carlo simulation based on 30-band k.p calculation. This effect has been demonstrated experimentally in Si nanowires by He and Yang. By including the well-known strain effect on the band structure, and by introducing a law of variation of the surface potential according to the applied mechanical stress, we can reproduce this effect. This variation of surface potential modulates the depletion depth and then the conductivity of the structure. This modulation induces a strong variation of the total amount of carriers available for the conduction, which increases drastically this piezoresistive effect. This is probably the main origin of this effect, which may be used to achieve high performance MEMS sensors.

  2. Quantitative copper measurement in oxidized p-type silicon wafers using microwave photoconductivity decay

    NASA Astrophysics Data System (ADS)

    Väinölä, H.; Saarnilehto, E.; Yli-Koski, M.; Haarahiltunen, A.; Sinkkonen, J.; Berenyi, G.; Pavelka, T.

    2005-07-01

    We propose a method to measure trace copper contamination in p-type silicon using the microwave photoconductivity decay (μ-PCD) technique. The method is based on the precipitation of interstitial copper, activated by high-intensity light, which results in enhanced minority carrier recombination activity. We show that there is a quantitative correlation between the enhanced recombination rate and the Cu concentration by comparing μ-PCD measurements with transient ion drift and total reflection x-ray fluorescence measurements. The results indicate that the method is capable of measuring Cu concentrations down to 1010cm-3. There are no limitations to wafer storage time if corona charge is used on the oxidized wafer surfaces as the charge prevents copper outdiffusion. We briefly discuss the role of oxide precipitates both in the copper precipitation and in the charge carrier recombination processes.

  3. Light Activated Copper Defects in P-Type Silicon Studied by PCD

    NASA Astrophysics Data System (ADS)

    Yli-Koski, M.; Väinölä, H.; Haarahiltunen, A.; Storgårds, J.; Saarnilehto, E.; Sinkkonen, J.

    2004-01-01

    We have studied copper defects in p-type silicon by measuring its precipitation kinetics by means of the microwave photoconductive decay (µPCD) technique. Copper atoms precipitated during high intensity light treatment at room temperature. We used the total reflection X-ray fluorescence (TXRF) and the transient ion drift (TID) techniques to determine the bulk concentration of copper. We estimated the density and the radius of the copper precipitates as well as the average capture cross-section for precipitated copper atoms from the measured copper precipitation time constant, bulk concentration of copper, and the change in the recombination rate. We also studied how the density of oxygen defect affects the copper precipitation. Our results show that copper precipitates at two different kinds of defects.

  4. DLTS study of defects in hydrogen plasma treated p-type silicon

    NASA Astrophysics Data System (ADS)

    Wu, L.; Leitch, A. W. R.

    2001-12-01

    A deep level transient spectroscopy (DLTS) study of defects found in float-zone p-type silicon exposed to a DC hydrogen plasma is reported. DLTS measurements of these samples revealed three deep levels. Two of the levels are broad, with ET- EV in the range 0.34-0.39 eV (H2) and 0.40-0.44 eV (H3); these appear as bands in the Arrhenius plot. The third level has an activation energy of 0.09 eV (H1). The variations in the capture cross-sections of H2 and H3 are believed to be strain-related. The concentration of H3 exceeds the other two levels and decreases rapidly into the samples with ∼10 15 cm -3 at a depth of 0.20 μm. H3 is tentatively ascribed to an extended defect.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. Precipitation of Cu and Ni in n- and p-type Czochralski-grown silicon characterized by photoluminescence imaging

    NASA Astrophysics Data System (ADS)

    Sun, Chang; Nguyen, Hieu T.; Rougieux, Fiacre E.; Macdonald, Daniel

    2017-02-01

    Photoluminescence (PL) images and micro-PL maps were taken on Cu- or Ni-doped monocrystalline silicon wafers, to investigate the distribution of the metal precipitates. Several n-type and p-type wafers were used in which Cu or Ni were introduced in the starting melt of the ingots and precipitated during the ingot cooling (as opposed to surface contamination). The micro-PL mapping allowed investigation of the metal precipitates with a higher spatial resolution. Markedly different precipitation patterns were observed in n- and p-type samples: in both Cu- and Ni-doped n-type samples, circular central regions and edge regions were observed. In these regions, particles were distributed randomly and homogeneously. In the p-type Cu-doped and Ni-doped samples, by contrast, the precipitates occurred in lines along <110> orientations. The difference in the precipitation behaviour in n- and p-type samples is conjectured to be caused by different concentrations of self-interstitials and vacancies remaining in the crystal during the ingot cooling: there are more vacancies in the n-type ingots but more interstitials in the p-type ingots. The dopant effects on the intrinsic point defect concentrations in silicon crystals and possible precipitation mechanisms are discussed based on the findings in this work and the literature.

  10. 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.

  11. Macropore formation in p-type silicon: toward the modeling of morphology.

    PubMed

    Slimani, Amel; Iratni, Aicha; Henry, Hervé; Plapp, Mathis; Chazalviel, Jean-Noël; Ozanam, François; Gabouze, Noureddine

    2014-01-01

    The formation of macropores in silicon during electrochemical etching processes has attracted much interest. Experimental evidences indicate that charge transport in silicon and in the electrolyte should realistically be taken into account in order to be able to describe the macropore morphology. However, up to now, none of the existing models has the requested degree of sophistication to reach such a goal. Therefore, we have undertaken the development of a mathematical model (phase-field model) to describe the motion and shape of the silicon/electrolyte interface during anodic dissolution. It is formulated in terms of the fundamental expression for the electrochemical potential and contains terms which describe the process of silicon dissolution during electrochemical attack in a hydrofluoric acid (HF) solution. It should allow us to explore the influence of the physical parameters on the etching process and to obtain the spatial profiles across the interface of various quantities of interest, such as the hole concentration, the current density, or the electrostatic potential. As a first step, we find that this model correctly describes the space charge region formed at the silicon side of the interface.

  12. Macropore formation in p-type silicon: toward the modeling of morphology

    PubMed Central

    2014-01-01

    The formation of macropores in silicon during electrochemical etching processes has attracted much interest. Experimental evidences indicate that charge transport in silicon and in the electrolyte should realistically be taken into account in order to be able to describe the macropore morphology. However, up to now, none of the existing models has the requested degree of sophistication to reach such a goal. Therefore, we have undertaken the development of a mathematical model (phase-field model) to describe the motion and shape of the silicon/electrolyte interface during anodic dissolution. It is formulated in terms of the fundamental expression for the electrochemical potential and contains terms which describe the process of silicon dissolution during electrochemical attack in a hydrofluoric acid (HF) solution. It should allow us to explore the influence of the physical parameters on the etching process and to obtain the spatial profiles across the interface of various quantities of interest, such as the hole concentration, the current density, or the electrostatic potential. As a first step, we find that this model correctly describes the space charge region formed at the silicon side of the interface. PMID:25386103

  13. Light-induced degradation in p-type gallium co-doped solar grade multicrystalline silicon wafers and solar cells

    NASA Astrophysics Data System (ADS)

    Ren, Xianpei; Cai, Lihan; Fan, Baodian; Cheng, Haoran; Zheng, Songsheng; Chen, Chao

    2013-12-01

    This letter focuses on the evolution under illumination of the minority carrier lifetime and conversion efficiency of p-type gallium (Ga) co-doped solar grade multicrystalline silicon wafers and solar cells. We present experimental data regarding the concentration of boron-oxygen (B-O) defects in this silicon when subjected to illumination, and the concentration was found to depend on [B]-[P] rather than [B] or the net doping p0([B] + [Ga] - [P]). This result implies that the compensated B is unable to form the B-O defect. Minority carrier lifetime and EQE measurements at different degradation states indicate that the B-O defect and Fe-acceptor pairs are the two key centers contributed to LID in this material.

  14. 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.

  15. 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.

  16. Low temperature iron gettering by grown-in defects in p-type Czochralski silicon

    NASA Astrophysics Data System (ADS)

    Zhu, Haiyan; Yu, Xuegong; Zhu, Xiaodong; Wu, Yichao; He, Jian; Vanhellemont, Jan; Yang, Deren

    2016-11-01

    Low temperature iron gettering in as-grown boron doped Czochralski silicon (Cz-Si) at temperatures between 220 and 500 °C is studied using microwave-photoconductive decay based minority carrier lifetime measurements. Scanning infrared microscopy technique is used to study the defect density/size distribution in the samples before and after anneal. It is found that the decrease of interstitial iron (Fei) concentration shows a double exponential dependence on annealing time at all temperatures. This suggests the existence of two sinks for Fei. Meanwhile, the observed bulk defect densities and sizes in contaminated and as-grown samples are nearly the same, implying that the grown-in defects could be the gettering centers in this process. The results are important for understanding and controlling low temperature Fei gettering during processing of Cz-Si based devices.

  17. Abnormal degradation of high-voltage p-type MOSFET with n+ polycrystalline silicon gate during AC stress

    NASA Astrophysics Data System (ADS)

    Lee, Dongjun; Joo, Ikhyung; Lee, Changsub; Song, Duheon; Choi, Byoungdeog

    2016-11-01

    We investigated the abnormal degradation of high-voltage p-type MOSFET (HV pMOSFET) under negative AC gate bias stress. In HV pMOSFET with n+ polycrystalline silicon (poly-Si) gate, the abnormal degradation occurs after the gradual degradation during negative AC stress. The abnormal degradation is suppressed by changing the gate material from n+ poly-Si to p+ poly-Si, and it is caused by hot holes produced by the impact ionization near the surface when electrons move from the gate toward the gate oxide. We suggest a possible mechanism to explain the improvement of degradation by using p+ poly-Si as a gate material.

  18. Detection of low-level copper contamination in p-type silicon by means of microwave photoconductive decay measurements

    NASA Astrophysics Data System (ADS)

    Yli-Koski, M.; Palokangas, M.; Haarahiltunen, A.; Väinölä, H.; Storgårds, J.; Holmberg, H.; Sinkkonen, J.

    2002-12-01

    In order to achieve a better understanding of the behaviour of copper in p-type silicon, studies of the recombination of copper were carried out by the microwave photoconductive decay measurement method (μ PCD) using high-intensity bias light. It was observed that in the presence of small oxygen precipitates, high-intensity light could be used to activate precipitation of interstitial copper. It is suggested that high-intensity light changes the charge state of interstitial copper from positive to neutral, which enhances the precipitation. The precipitation follows Ham's kinetics and results in an increase in the recombination rate, which is detectable even with very low copper concentrations. This phenomenon can be used to detect low levels of copper contamination by the μ PCD method. In addition, it was observed that out-diffusion as well as in-diffusion of interstitial copper could be affected by an external corona charge. Thus, it is suggested that copper atoms do not form stable bonds at the Si-SiO2 interface after out-diffusion from bulk silicon.

  19. 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.

  20. Giant piezoresistance of p-type nano-thick silicon induced by interface electron trapping instead of 2D quantum confinement.

    PubMed

    Yang, Yongliang; Li, Xinxin

    2011-01-07

    The p-type silicon giant piezoresistive coefficient is measured in top-down fabricated nano-thickness single-crystalline-silicon strain-gauge resistors with a macro-cantilever bending experiment. For relatively thicker samples, the variation of piezoresistive coefficient in terms of silicon thickness obeys the reported 2D quantum confinement effect. For ultra-thin samples, however, the variation deviates from the quantum-effect prediction but increases the value by at least one order of magnitude (compared to the conventional piezoresistance of bulk silicon) and the value can change its sign (e.g. from positive to negative). A stress-enhanced Si/SiO(2) interface electron-trapping effect model is proposed to explain the 'abnormal' giant piezoresistance that should be originated from the carrier-concentration change effect instead of the conventional equivalent mobility change effect for bulk silicon piezoresistors. An interface state modification experiment gives preliminary proof of our analysis.

  1. Effect of dopant compensation on the temperature dependence of the transport properties in p-type monocrystalline silicon

    SciTech Connect

    Veirman, J.; Martel, B.; Dubois, S.; Stendera, J.

    2014-02-28

    In this paper, we investigate the temperature variations of the hole transport properties in initially uncompensated boron-doped Czochralski silicon progressively compensated through thermal donors activation. After each donor generation anneal, the boron and thermal donor concentrations in the samples are determined using (1) the change in carrier concentration at room temperature and (2) the analysis of the temperature variation of the carrier concentration in the range 77–350 K. By comparing both methods with theory, evidence is brought that down to 77 K the Hall factor is unaffected by compensation up to high compensation levels. This is of great interest for researchers working on new solar-grade materials since it nicely suggests that Hall factor models previously established for non-compensated silicon can be applied to compensated samples, for example, when extracting the individual dopant concentrations from the temperature variations of the hole concentration. At very high compensation levels, anomalous Hall data lead to erroneously low carrier mobility values. We showed that this artifact was due to the formation of a n-p-n transistor, arising from the preferential formation of thermal donors in the sample's subsurface. After rejecting these unphysical data from the analysis, we confirm that the hole mobility is greatly affected by compensation in the temperature range investigated. We eventually confront our experimental data to current mobility models and discuss the possible sources of discrepancy.

  2. 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.

  3. 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.

  4. Pore size modulation in electrochemically etched macroporous p-type silicon monitored by FFT impedance spectroscopy and Raman scattering.

    PubMed

    Quiroga-González, Enrique; Carstensen, Jürgen; Glynn, Colm; O'Dwyer, Colm; Föll, Helmut

    2014-01-07

    The understanding of the mechanisms of macropore formation in p-type Si with respect to modulation of the pore diameter is still in its infancy. In the present work, macropores with significantly modulated diameters have been produced electrochemically in p-type Si. The effect of the current density and the amount of surfactant in the etching solution are shown to influence the modulation in pore diameter and morphology. Data obtained during the etching process by in situ FFT impedance spectroscopy correlate the pore diameter variation with certain time constants found in the kinetics of the dissolution process. Raman scattering and electron microscopy confirm the mesoscopic structure and roughening of the pore walls. Spectroscopic and microscopic methods confirm that the pore wall morphology is correlated with the conditions of pore modulation.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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

  11. Photo-induced electrochemical anodization of p-type silicon: achievement and demonstration of long term surface stability.

    PubMed

    Dhanekar, Saakshi; Islam, S S; Harsh

    2012-06-15

    Surface stability is achieved and demonstrated by porous silicon (PS) fabricated using a wavelength-dependent photo-electrochemical (PEC) anodization technique. During anodization, the photon flux for all wavelengths was kept constant while only the effect of light wavelength on the surface morphology of PS was investigated. PS optical sensors were realized, characterized and tested using a photoluminescence (PL) quenching technique. An aliphatic chain of alcohols (methanol to n-octanol) was detected in the range of 10-200 ppm. Long term surface stability was observed from samples prepared under red (750-620 nm) and green illumination (570-495 nm), where the PL quenching cycles evoke the possibility of using PS for stable sensor device applications. This study provides a route for preparing highly sensitive organic vapour sensors with a precise selection of the fabrication parameters and demonstrating their prolonged performance.

  12. 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.; Bomben, M.; Boscardin, M.; Bosisio, L.; Chauveau, J.; Giacomini, G.; La Rosa, A.; Marchiori, G.; Zorzi, N.

    2014-11-01

    In view of the LHC upgrade for the high luminosity phase (HL-LHC), the ATLAS experiment is planning to replace the inner detector with an all-silicon system. The n-in-p bulk technology represents a valid solution for the modules of most of the layers, given the significant radiation hardness of this option and the reduced cost. The large area necessary to instrument the outer layers will demand to tile the sensors, a solution for which the inefficient region at the border of each sensor needs to be reduced to the minimum size. This paper reports on a joint R&D project by the ATLAS LPNHE Paris group and FBK Trento on a novel n-in-p edgeless planar pixel design, based on the deep-trench process available at FBK.

  13. Further evidence for the quantum confined electrochemistry model of the formation mechanism of p - -type porous silicon

    NASA Astrophysics Data System (ADS)

    Jia, L.; Zang, S. L.; Wong, S. P.; Wilson, I. H.; Hark, S. K.; Liu, Z. F.; Cai, S. M.

    1996-11-01

    Two types of p- porous silicon (PS) were formed in HF solutions of different concentrations. One type with nanoscale (NS) dimensions of about 3 nm and the other with dimensions of about 5 nm. PS samples formed in the lower concentration of HF were anodized again in the higher concentration of HF and vice versa. The photoluminescence peak position and, thus, the size of NS units of PS were found to be related to the concentration of HF in which the PS is formed, independent of the forming time. The larger NS units of PS can be further electrochemically etched by anodization, while the smaller ones cannot. These results give a confirming evidence for the quantum confined electrochemistry model of the formation mechanism of PS based on the quantum confinement effect and classical electrochemical theory [S. L. Zhang, K. S. Ho, Y. T. Hou, B. D. Qian, P. Diao, and S. M. Cai, Appl. Phys. Lett. 62, 642 (1993)].

  14. The electrical properties of photodiodes based on nanostructure gallium doped cadmium oxide/ p-type silicon junctions

    NASA Astrophysics Data System (ADS)

    Çavaş, M.; Yakuphanoğlu, F.; Karataş, Ş.

    2017-04-01

    Gallium doped cadmium-oxide (CdO: Ga) thin films were successfully deposited by sol-gel spin coating method on p-type Si substrate. The electrical properties of the photodiode based on nanostructure Ga doped n-CdO/ p-Si junctions were investigated. The current-voltage ( I- V) characteristics of the structure were investigated under various light intensity and dark. It was observed that generated photocurrent of the Au/ n-CdO/p-Si junctions depended on light intensity. The capacitance-voltage and conductance-voltage measurements were carried out for this diode in the frequency range between 100 and 1000 kHz at room temperature by steps of 100 kHz. The capacitance decreased with increasing frequency due to a continuous distribution of the interface states. These results suggested that the Au/ n-CdO/ p-Si Schottky junctions could be utilized as a photosensor. Furthermore, the voltage and frequency dependence of series resistance were calculated from the C- V and G/ω-V measurements and plotted as functions of voltage and frequency. The distribution profile of R S - V gave a peak in the depletion region at low frequencies and disappeared with increasing frequencies.

  15. The electrical properties of photodiodes based on nanostructure gallium doped cadmium oxide/p-type silicon junctions

    NASA Astrophysics Data System (ADS)

    Çavaş, M.; Yakuphanoğlu, F.; Karataş, Ş.

    2017-01-01

    Gallium doped cadmium-oxide (CdO: Ga) thin films were successfully deposited by sol-gel spin coating method on p-type Si substrate. The electrical properties of the photodiode based on nanostructure Ga doped n-CdO/p-Si junctions were investigated. The current-voltage (I-V) characteristics of the structure were investigated under various light intensity and dark. It was observed that generated photocurrent of the Au/n-CdO/p-Si junctions depended on light intensity. The capacitance-voltage and conductance-voltage measurements were carried out for this diode in the frequency range between 100 and 1000 kHz at room temperature by steps of 100 kHz. The capacitance decreased with increasing frequency due to a continuous distribution of the interface states. These results suggested that the Au/n-CdO/p-Si Schottky junctions could be utilized as a photosensor. Furthermore, the voltage and frequency dependence of series resistance were calculated from the C-V and G/ω-V measurements and plotted as functions of voltage and frequency. The distribution profile of R S -V gave a peak in the depletion region at low frequencies and disappeared with increasing frequencies.

  16. 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.

  17. The performance of Y2O3 as interface layer between La2O3 and p-type silicon substrate

    NASA Astrophysics Data System (ADS)

    Wang, Shulong; Chen, Yuhai; Liu, Hongxia; Zhang, Hailin

    2016-11-01

    In this study, the performance of Y2O3 as interface layer between La2O3 and p-type silicon substrate is studied with the help of atomic layer deposition (ALD) and magnetron sputtering technology. The surface morphology of the bilayer films with different structures are observed after rapid thermal annealing (RTA) by atomic force microscopy (AFM). The results show that Y2O3/Al2O3/Si structure has a larger number of small spikes on the surface and its surface roughness is worse than Al2O3/Y2O3/Si structure. The reason is that the density of Si substrate surface is much higher than that of ALD growth Al2O3. With the help of high-frequency capacitance-voltage(C-V) measurement and conductivity method, the density of interface traps can be calculated. After a high temperature annealing, the metal silicate will generate at the substrate interface and result in silicon dangling bond and interface trap charge, which has been improved by X-ray photoelectron spectroscopy (XPS) and interface trap charge density calculation. The interface trapped charge density of La2O3/Al2O3/Si stacked gate structure is lower than that of La2O3/Y2O3/Si gate structure. If Y2O3 is used to replace Al2O3 as the interfacial layer, the accumulation capacitance will increase obviously, which means lower equivalent oxide thickness (EOT). Our results show that interface layer Y2O3 grown by magnetron sputtering can effectively ensure the interface traps near the substrate at relative small level while maintain a relative higher dielectric constant than Al2O3.

  18. 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.

  19. 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.

  20. 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.

  1. Ultralow Contact Resistivity for a Metal/p-Type Silicon Interface by High-Concentration Germanium and Boron Doping Combined with Low-Temperature Annealing

    NASA Astrophysics Data System (ADS)

    Murakoshi, Atsushi; Iwase, Masao; Niiyama, Hiromi; Koike, Mitsuo; Suguro, Kyoichi

    2013-07-01

    A contact resistivity of 6.9×10-9 Ω.cm2 has been obtained in an AlSi (1 wt %)-Cu (0.5 wt %) alloy/silicon system by using heavy-dose ion implantations of germanium and boron combined with low-temperature annealing. The analysis of the combined state showed that B12 cluster was incorporated and the supersaturation activation layer was formed into the region where germanium separated. Separated germanium is expected to have high interface state density. It is considered that this interface state density also has a Fermi level, and in order to reduce the difference from the Fermi level of the substrate, the charge moves to interface state density from the substrate. As a result, it is not based on a metallic material but a work function becomes small because pinning by which a Fermi level is fixed to interface state density occurs owing to the substrate/metal interface. It is considered to be attributable to the existence of a Ge-rich layer formed by low-temperature annealing, and a supersaturation activation layer that lowers contact resistance was formed.

  2. Initial experience with the CDF layer 00 silicon detector

    SciTech Connect

    C. Hill

    2003-03-17

    We report on initial experience with the CDF Layer 00 Detector. Layer 00 is an innovative, low-mass, silicon detector installed in CDF during the upgrade for Run 2A of the Tevatron. Noise pickup present during operation at CDF is discussed. An event-by-event pedestal correction implemented by CDF is presented. This off-line solution prevents L00 from being used in the current incarnation of the on-line displaced track trigger. Preliminary performance of Layer 00 is described.

  3. Crystalline Silicon Short-Circuit Current Degradation Study: Initial Results

    SciTech Connect

    Osterwald, C. R.; Pruett, J.; Moriarty, T.

    2005-02-01

    Following our observation of slow degradation of short-circuit current (Isc) in crystalline silicon (x-Si) modules that was correlated with ultraviolet (UV) exposure dose, we initiated a new study of individual x-Si cells designed to determine the degradation cause. In this paper, we report the initial results of this study, which has accumulated 1056 MJ/m2 of UV dose from 1-sun metal-halide irradiance, equivalent to 3.8 years at our test site. At this time, the control samples are unchanged, the unencapsulated samples have lost about 2% of Isc, and the samples encapsulated in module-style packages have declined from 1% to 3%, depending on the cell technology.

  4. Initial Steps of Rubicene Film Growth on Silicon Dioxide

    PubMed Central

    2013-01-01

    The film growth of the conjugated organic molecule rubicene on silicon dioxide was studied in detail. Since no structural data of the condensed material were available, we first produced high quality single crystals from solution and determined the crystal structure. This high purity material was used to prepare ultrathin films under ultrahigh vacuum conditions, by physical vapor deposition. Thermal desorption spectroscopy (TDS) was applied to delineate the adsorption and desorption kinetics. It could be shown that the initial sticking coefficient is only 0.2 ± 0.05, but the sticking coefficient increases with increasing coverage. TDS further revealed that first a closed, weakly bound bilayer develops (wetting layer), which dewets after further deposition of rubicene, leading to an island-like layer. These islands are crystalline and exhibit the same structure as the solution grown crystals. The orientation of the crystallites is with the (001) plane parallel to the substrate. A dewetting of the closed bilayer was also observed when the film was exposed to air. Furthermore, Ostwald ripening of the island-like film takes place under ambient conditions, leading to films composed of few, large crystallites. From TDS, we determined the heat of evaporation from the multilayer islands to be 1.47 eV, whereas the desorption energy from the first layer is only 1.25 eV. PMID:23476720

  5. Initial Steps of Rubicene Film Growth on Silicon Dioxide.

    PubMed

    Scherwitzl, Boris; Lukesch, Walter; Hirzer, Andreas; Albering, Jörg; Leising, Günther; Resel, Roland; Winkler, Adolf

    2013-02-28

    The film growth of the conjugated organic molecule rubicene on silicon dioxide was studied in detail. Since no structural data of the condensed material were available, we first produced high quality single crystals from solution and determined the crystal structure. This high purity material was used to prepare ultrathin films under ultrahigh vacuum conditions, by physical vapor deposition. Thermal desorption spectroscopy (TDS) was applied to delineate the adsorption and desorption kinetics. It could be shown that the initial sticking coefficient is only 0.2 ± 0.05, but the sticking coefficient increases with increasing coverage. TDS further revealed that first a closed, weakly bound bilayer develops (wetting layer), which dewets after further deposition of rubicene, leading to an island-like layer. These islands are crystalline and exhibit the same structure as the solution grown crystals. The orientation of the crystallites is with the (001) plane parallel to the substrate. A dewetting of the closed bilayer was also observed when the film was exposed to air. Furthermore, Ostwald ripening of the island-like film takes place under ambient conditions, leading to films composed of few, large crystallites. From TDS, we determined the heat of evaporation from the multilayer islands to be 1.47 eV, whereas the desorption energy from the first layer is only 1.25 eV.

  6. Comparative study of initial stages of copper immersion deposition on bulk and porous silicon

    NASA Astrophysics Data System (ADS)

    Bandarenka, Hanna; Prischepa, Sergey L.; Fittipaldi, Rosalba; Vecchione, Antonio; Nenzi, Paolo; Balucani, Marco; Bondarenko, Vitaly

    2013-02-01

    Initial stages of Cu immersion deposition in the presence of hydrofluoric acid on bulk and porous silicon were studied. Cu was found to deposit both on bulk and porous silicon as a layer of nanoparticles which grew according to the Volmer-Weber mechanism. It was revealed that at the initial stages of immersion deposition, Cu nanoparticles consisted of crystals with a maximum size of 10 nm and inherited the orientation of the original silicon substrate. Deposited Cu nanoparticles were found to be partially oxidized to Cu2O while CuO was not detected for all samples. In contrast to porous silicon, the crystal orientation of the original silicon substrate significantly affected the sizes, density, and oxidation level of Cu nanoparticles deposited on bulk silicon.

  7. Plasma-initiated rehydrogenation of amorphous silicon to increase the temperature processing window of silicon heterojunction solar cells

    NASA Astrophysics Data System (ADS)

    Shi, Jianwei; Boccard, Mathieu; Holman, Zachary

    2016-07-01

    The dehydrogenation of intrinsic hydrogenated amorphous silicon (a-Si:H) at temperatures above approximately 300 °C degrades its ability to passivate silicon wafer surfaces. This limits the temperature of post-passivation processing steps during the fabrication of advanced silicon heterojunction or silicon-based tandem solar cells. We demonstrate that a hydrogen plasma can rehydrogenate intrinsic a-Si:H passivation layers that have been dehydrogenated by annealing. The hydrogen plasma treatment fully restores the effective carrier lifetime to several milliseconds in textured crystalline silicon wafers coated with 8-nm-thick intrinsic a-Si:H layers after annealing at temperatures of up to 450 °C. Plasma-initiated rehydrogenation also translates to complete solar cells: A silicon heterojunction solar cell subjected to annealing at 450 °C (following intrinsic a-Si:H deposition) had an open-circuit voltage of less than 600 mV, but an identical cell that received hydrogen plasma treatment reached a voltage of over 710 mV and an efficiency of over 19%.

  8. 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.

  9. 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.

  10. p-Type Transparent Electronics

    DTIC Science & Technology

    2003-09-25

    semiconductor surface heavily doped ...successfully doped both n-type and p-type. 2.1.3 CuInO2 CuInO2 is a particularly interesting transparent conductor because it has been successfully doped ...integra- tion. CuInO2 is doped n-type by the replacement of In 3+ with Sn4+, and p-type by the replacement of In3+ with Ca2+. Neither n-CuInO2 nor p-CuInO2

  11. Initiation time of near-infrared laser-induced slip on the surface of silicon wafers

    SciTech Connect

    Choi, Sungho; Jhang, Kyung-Young

    2014-06-23

    We have determined the initiation time of laser-induced slip on a silicon wafer surface subjected to a near-infrared continuous-wave laser by numerical simulations and experiments. First, numerical analysis was performed based on the heat transfer and thermoelasticity model to calculate the resolved shear stress and the temperature-dependent yield stress. Slip initiation time was predicted by finding the time at which the resolved shear stress reached the yield stress. Experimentally, the slip initiation time was measured by using a laser scattering technique that collects scattered light from the silicon wafer surface and detects strong scattering when the surface slip is initiated. The surface morphology of the silicon wafer surface after laser irradiation was also observed using an optical microscope to confirm the occurrence of slip. The measured slip initiation times agreed well with the numerical predictions.

  12. Initial results for the silicon monolithically interconnected solar cell product

    NASA Technical Reports Server (NTRS)

    Dinetta, L. C.; Shreve, K. P.; Cotter, J. E.; Barnett, A. M.

    1995-01-01

    This proprietary technology is based on AstroPower's electrostatic bonding and innovative silicon solar cell processing techniques. Electrostatic bonding allows silicon wafers to be permanently attached to a thermally matched glass superstrate and then thinned to final thicknesses less than 25 micron. These devices are based on the features of a thin, light-trapping silicon solar cell: high voltage, high current, light weight (high specific power) and high radiation resistance. Monolithic interconnection allows the fabrication costs on a per watt basis to be roughly independent of the array size, power or voltage, therefore, the cost effectiveness to manufacture solar cell arrays with output powers ranging from milliwatts up to four watts and output voltages ranging from 5 to 500 volts will be similar. This compares favorably to conventionally manufactured, commercial solar cell arrays, where handling of small parts is very labor intensive and costly. In this way, a wide variety of product specifications can be met using the same fabrication techniques. Prototype solar cells have demonstrated efficiencies greater than 11%. An open-circuit voltage of 5.4 volts, fill factor of 65%, and short-circuit current density of 28 mA/sq cm at AM1.5 illumination are typical. Future efforts are being directed to optimization of the solar cell operating characteristics as well as production processing. The monolithic approach has a number of inherent advantages, including reduced cost per interconnect and increased reliability of array connections. These features make this proprietary technology an excellent candidate for a large number of consumer products.

  13. Determination of Initial Crack Strength of Silicon Die Using Acoustic Emission Technique

    NASA Astrophysics Data System (ADS)

    Chen, Pei-Chi; Su, Yen-Fu; Yang, Shin-Yueh; Liang, Steven Y.; Chiang, Kuo-Ning

    2015-07-01

    The current market demand for high-efficiency, high-performance, small-sized electronic products has focused attention on the use of three-dimensional (3D) integrated circuits (IC) in the design of electronic packaging. Silicon wafers can be ground and polished to reduce their thickness and increase the chip stacking density. However, microcracks can result from the thinning and stacking process or during use of an electronic device over time; therefore, estimation of the cracking strength is an important issue in 3D IC packaging. This research combined the ball breaker test (BBT) with an acoustic emission (AE) system to measure the allowable force on a silicon die. To estimate the initial crack strength of a silicon die, the BBT was combined with finite-element (FE) analysis. The AE system can detect the initial crack and the subsequent bulk failure of the silicon die individually, thus avoiding overestimation of the die strength. In addition, the results of the modified ball breaker test showed that edge chipping did not affect the silicon die strength. However, the failure force and silicon die strength were reduced as the surface roughness of the test specimen increased. Thus, surface roughness must be controlled in the BBT to prevent underestimation of the silicon die strength.

  14. An initial in-orbit performance study of Silicon Tungsten tracKer on DAMPE

    NASA Astrophysics Data System (ADS)

    Qiao, Rui

    2016-07-01

    The dark matter particle explorer (DAMPE) was launched in December 2015 and taking data since then. One of its major payloads, Silicon Tungsten tracker (STK) plays an important role in tracking and ion charge identification. From the study of first few months of data collection of STK, the noise behaviors, DAC/MIPs calibration and an initial charge detection result will be presented.

  15. Silicon-based bridge wire micro-chip initiators for bismuth oxide-aluminum nanothermite

    NASA Astrophysics Data System (ADS)

    Staley, C. S.; Morris, C. J.; Thiruvengadathan, R.; Apperson, S. J.; Gangopadhyay, K.; Gangopadhyay, S.

    2011-11-01

    We present a micro-manufacturing process for fabricating silicon-based bridge wire micro-chip initiators with the capacity to liberate joules of chemical energy at the expense of micro joules of input electrical energy. The micro-chip initiators are assembled with an open material reservoir utilizing a novel 47 °C melting point solder alloy bonding procedure and integrated with a bismuth oxide-aluminum nanothermite energetic composite. The electro-thermal conversion efficiency of the initiators is enhanced by the use of a nanoporous silicon bed which impedes thermal coupling between the bridge wire and bulk silicon substrate while maintaining the structural integrity of the device. Electrical behaviors of the ignition elements are investigated to extract minimum input power and energy requirements of 382.4 mW and 26.51 µJ, respectively, both in the absence and presence of an injected bismuth oxide-aluminum nanothermite composition. Programmed combustion of bismuth oxide-aluminum nanothermite housed within these initiators is demonstrated with a success rate of 100% over a 30 to 80 µJ range of firing energies and ignition response times of less than 2 µs are achieved in the high input power operation regime. The micro-initiators reported here are intended for use in miniaturized actuation technologies.

  16. Surface-initiated hyperbranched polyglycerol as an ultralow-fouling coating on glass, silicon, and porous silicon substrates.

    PubMed

    Moore, Eli; Delalat, Bahman; Vasani, Roshan; McPhee, Gordon; Thissen, Helmut; Voelcker, Nicolas H

    2014-09-10

    Anionic ring-opening polymerization of glycidol was initiated from activated glass, silicon, and porous silicon substrates to yield thin, ultralow-fouling hyperbranched polyglycerol (HPG) graft polymer coatings. Substrates were activated by deprotonation of surface-bound silanol functionalities. HPG polymerization was initiated upon the addition of freshly distilled glycidol to yield films in the nanometer thickness range. X-ray photoelectron spectroscopy, contact angle measurements, and ellipsometry were used to characterize the resulting coatings. The antifouling properties of HPG-coated surfaces were evaluated in terms of protein adsorption and the attachment of mammalian cells. The adsorption of bovine serum albumin and collagen type I was found to be reduced by as much as 97 and 91%, respectively, in comparison to untreated surfaces. Human glioblastoma and mouse fibroblast attachment was reduced by 99 and 98%, respectively. HPG-grafted substrates outperformed polyethylene glycol (PEG) grafted substrates of comparable thickness under the same incubation conditions. Our results demonstrate the effectiveness of antifouling HPG graft polymer coatings on a selected range of substrate materials and open the door for their use in biomedical applications.

  17. Void initiation from interfacial debonding of spherical silicon particles inside a silicon-copper nanocomposite: a molecular dynamics study

    NASA Astrophysics Data System (ADS)

    Cui, Yi; Chen, Zengtao

    2017-02-01

    Silicon particles with diameters from 1.9 nm to 30 nm are embedded in a face-centered-cubic copper matrix to form nanocomposite specimens for simulation. The interfacial debonding of silicon particles from the copper matrix and the subsequent growth of nucleated voids are studied via molecular dynamics (MD). The MD results are examined from several different perspectives. The overall mechanical performance is monitored by the average stress-strain response and the accumulated porosity. The ‘relatively farthest-traveled’ atoms are identified to characterize the onset of interfacial debonding. The relative displacement field is plotted to illustrate both subsequent interfacial debonding and the growth of a nucleated void facilitated by a dislocation network. Our results indicate that the initiation of interfacial debonding is due to the accumulated surface stress if the matrix is initially dislocation-free. However, pre-existing dislocations can make a considerable difference. In either case, the dislocation emission also contributes to the subsequent debonding process. As for the size effect, the debonding of relatively larger particles causes a drop in the stress-strain curve. The volume fraction of second-phase particles is found to be more influential than the size of the simulation box on the onset of interfacial debonding. The volume fraction of second-phase particles also affects the shape of the nucleated void and, therefore, influences the stress response of the composite.

  18. 3-D patterning of silicon by laser-initiated, liquid-assisted colloidal (LILAC) lithography.

    PubMed

    Ulmeanu, M; Grubb, M P; Jipa, F; Quignon, B; Ashfold, M N R

    2015-06-01

    We report a comprehensive study of laser-initiated, liquid-assisted colloidal (LILAC) lithography, and illustrate its utility in patterning silicon substrates. The method combines single shot laser irradiation (frequency doubled Ti-sapphire laser, 50fs pulse duration, 400nm wavelength) and medium-tuned optical near-field effects around arrays of silica colloidal particles to achieve 3-D surface patterning of silicon. A monolayer (or multilayers) of hexagonal close packed silica colloidal particles act as a mask and offer a route to liquid-tuned optical near field enhancement effects. The resulting patterns are shown to depend on the difference in refractive index of the colloidal particles (ncolloid) and the liquid (nliquid) in which they are immersed. Two different topographies are demonstrated experimentally: (a) arrays of bumps, centred beneath the original colloidal particles, when using liquids with nliquidncolloid - and explained with the aid of complementary Mie scattering simulations. The LILAC lithography technique has potential for rapid, large area, organized 3-D patterning of silicon (and related) substrates.

  19. Synthesis of Poly-Silicon Thin Films on Glass Substrate Using Laser Initiated Metal Induced Crystallization of Amorphous Silicon for Space Power Application

    NASA Technical Reports Server (NTRS)

    Abu-Safe, Husam H.; Naseem, Hameed A.; Brown, William D.

    2007-01-01

    Poly-silicon thin films on glass substrates are synthesized using laser initiated metal induced crystallization of hydrogenated amorphous silicon films. These films can be used to fabricate solar cells on low cost glass and flexible substrates. The process starts by depositing 200 nm amorphous silicon films on the glass substrates. Following this, 200 nm of sputtered aluminum films were deposited on top of the silicon layers. The samples are irradiated with an argon ion cw laser beam for annealing. Laser power densities ranging from 4 to 9 W/cm2 were used in the annealing process. Each area on the sample is irradiated for a different exposure time. Optical microscopy was used to examine any cracks in the films and loss of adhesion to the substrates. X-Ray diffraction patterns from the initial results indicated the crystallization in the films. Scanning electron microscopy shows dendritic growth. The composition analysis of the crystallized films was conducted using Energy Dispersive x-ray Spectroscopy. The results of poly-silicon films synthesis on space qualified flexible substrates such as Kapton are also presented.

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

    DOE PAGES

    Katoh, Yutai; Ozawa, Kazumi; Shimoda, Kazuya; ...

    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

  1. 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.

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

    SciTech Connect

    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 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.

  3. Rethinking the P-type ATPase problem.

    PubMed

    Scarborough, Gene A

    2003-11-01

    There are very good reasons to stop thinking about the molecular mechanism of the P-type ion-translocating ATPases in terms of the traditional E1E2 model and to start thinking about it in more progressive ways. This makes it possible to see the ion-transport cycle as a rational series of discrete steps with well defined driving forces, including the crucial energy transduction step, where the chemical energy of ATP hydrolysis is exchanged for the osmotic energy of an ion gradient. Importantly, although major enzyme conformational changes accompany each of these steps, none of them drive the energy coupling reaction. Thus, neither the E1E2 model nor conformational energy coupling, the cornerstones of traditional thinking about the P-type ATPases, are reliable paradigms for future efforts to understand how these transporters work. Alternatives must be seriously considered.

  4. 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.

  5. 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.

  6. Ab-initio simulations on initial growth steps of high-K oxides on silicon

    NASA Astrophysics Data System (ADS)

    Bloechl, Peter E.

    2003-03-01

    One of the most acute challenges of semiconductor industry is the introduction of new so-called high-K gate oxides. Conventional SiO2 based gate oxides need to be replaced in order to avoid quantum mechanical leakage currents through ultrathin oxide layers. State of the art electronic structure calculations and ab-initio molecular dynamics simulations of the deposition of metals onto silicon and the formation of oxides have been performed. Atomic structure, chemical binding and electronic structure have been analyzed for a wide range of different adsorption structures of Zr, Hf, and Sr on silicon. Silicide formation and the step-wise formation of the oxides have been investigated. Particular emphasis will be given to the formation of the interface between SrTiO3 and silicon (001).

  7. Preparation of High Silicon Electrical Steel Sheets with Strong {100} Recrystallization Texture by the Texture Inheritance of Initial Columnar Grains

    NASA Astrophysics Data System (ADS)

    Pan, Hongjiang; Zhang, Zhihao; Xie, Jianxin

    2016-05-01

    Texture evolutions and recrystallization texture features in warm- and cold-rolled sheets of high silicon electrical steel with two different initial microstructures (columnar-grained and equiaxed-grained microstructures) were investigated. The relationships between the recrystallization textures and the initial textures (the textures before rolling) of the samples were analyzed. The results showed that after annealing at 1073 K (800 °C) for 1 hour, strong {100} recrystallization textures with volume fractions of more than 47 pct were obtained in the columnar-grained samples fabricated by warm and cold rolling along the growing direction of the columnar grains. While after rolling and annealing in the same processes, only 12.8 pct volume fractions of {100} recrystallization texture were revealed in the equiaxed-grained samples. The formation of strong {100} recrystallization texture in the annealed sheets of high silicon electrical steel with initial columnar grains was attributed to the favorable texture inheritance of the initial texture during rolling and annealing. The columnar grains of strong near {100}<001> ({100}<001> {310}<001>) orientation in the samples before rolling were transferred into deformed grains with orientations such as {100}<011> and {100}<012>. after rolling. Afterwards, these deformed grains were further transferred into {100} oriented recrystallized grains, which formed strong {100} recrystallization texture in the annealed sheets and exhibited preferable soft magnetic properties.

  8. Robustness up to 400°C of the passivation of c-Si by p-type a-Si:H thanks to ion implantation

    NASA Astrophysics Data System (ADS)

    Defresne, A.; Plantevin, O.; Roca i Cabarrocas, Pere

    2016-12-01

    Heterojunction solar cells based on crystalline silicon (c-Si) passivated by hydrogenated amorphous silicon (a-Si:H) thin films are one of the most promising architectures for high energy conversion efficiency. Indeed, a-Si:H thin films can passivate both p-type and n-type wafers and can be deposited at low temperature (<200°C) using PECVD. However, such passivation layers, in particular p-type a-Si:H, show a dramatic degradation in passivation quality above 200°C. Yet, annealing at 300 - 400°C the TCO layer and metallic contacts is highly desirable to reduce the contact resistance as well as the TCO optical absorption. In this work, we show that as expected, ion implantation (5 - 30 keV) introduces defects at the c-Si/a-Si:H interface which strongly degrade the effective lifetime, down to a few micro-seconds. However, the passivation quality can be restored and lifetime values can be improved up to 2 ms over the initial value with annealing. We show here that effective lifetimes above 1 ms can be maintained up to 380°C, opening up the possibility for higher process temperatures in silicon heterojunction device fabrication.

  9. Initial steps toward the realization of large area arrays of single photon counting pixels based on polycrystalline silicon TFTs

    NASA Astrophysics Data System (ADS)

    Liang, Albert K.; Koniczek, Martin; Antonuk, Larry E.; El-Mohri, Youcef; Zhao, Qihua; Jiang, Hao; Street, Robert A.; Lu, Jeng Ping

    2014-03-01

    The thin-film semiconductor processing methods that enabled creation of inexpensive liquid crystal displays based on amorphous silicon transistors for cell phones and televisions, as well as desktop, laptop and mobile computers, also facilitated the development of devices that have become ubiquitous in medical x-ray imaging environments. These devices, called active matrix flat-panel imagers (AMFPIs), measure the integrated signal generated by incident X rays and offer detection areas as large as ~43×43 cm2. In recent years, there has been growing interest in medical x-ray imagers that record information from X ray photons on an individual basis. However, such photon counting devices have generally been based on crystalline silicon, a material not inherently suited to the cost-effective manufacture of monolithic devices of a size comparable to that of AMFPIs. Motivated by these considerations, we have developed an initial set of small area prototype arrays using thin-film processing methods and polycrystalline silicon transistors. These prototypes were developed in the spirit of exploring the possibility of creating large area arrays offering single photon counting capabilities and, to our knowledge, are the first photon counting arrays fabricated using thin film techniques. In this paper, the architecture of the prototype pixels is presented and considerations that influenced the design of the pixel circuits, including amplifier noise, TFT performance variations, and minimum feature size, are discussed.

  10. Initial stem cell adhesion on porous silicon surface: molecular architecture of actin cytoskeleton and filopodial growth

    NASA Astrophysics Data System (ADS)

    Collart-Dutilleul, Pierre-Yves; Panayotov, Ivan; Secret, Emilie; Cunin, Frédérique; Gergely, Csilla; Cuisinier, Frédéric; Martin, Marta

    2014-10-01

    The way cells explore their surrounding extracellular matrix (ECM) during development and migration is mediated by lamellipodia at their leading edge, acting as an actual motor pulling the cell forward. Lamellipodia are the primary area within the cell of actin microfilaments (filopodia) formation. In this work, we report on the use of porous silicon (pSi) scaffolds to mimic the ECM of mesenchymal stem cells from the dental pulp (DPSC) and breast cancer (MCF-7) cells. Our atomic force microscopy (AFM), fluorescence microscopy, and scanning electron microscopy (SEM) results show that pSi promoted the appearance of lateral filopodia protruding from the DPSC cell body and not only in the lamellipodia area. The formation of elongated lateral actin filaments suggests that pores provided the necessary anchorage points for protrusion growth. Although MCF-7 cells displayed a lower presence of organized actin network on both pSi and nonporous silicon, pSi stimulated the formation of extended cell protrusions.

  11. Effect of the initial structure on the electrical property of crystalline silicon films deposited on glass by hot-wire chemical vapor deposition.

    PubMed

    Chung, Yung-Bin; Lee, Sang-Hoon; Bae, Sung-Hwan; Park, Hyung-Ki; Jung, Jae-Soo; Hwang, Nong-Moon

    2012-07-01

    Crystalline silicon films on an inexpensive glass substrate are currently prepared by depositing an amorphous silicon film and then crystallizing it by excimer laser annealing, rapid thermal annealing, or metal-induced crystallization because crystalline silicon films cannot be directly deposited on glass at a low temperature. It was recently shown that by adding HCI gas in the hot-wire chemical vapor deposition (HWCVD) process, the crystalline silicon film can be directly deposited on a glass substrate without additional annealing. The electrical properties of silicon films prepared using a gas mixture of SiH4 and HCl in the HWCVD process could be further improved by controlling the initial structure, which was achieved by adjusting the delay time in deposition. The size of the silicon particles in the initial structure increased with increasing delay time, which increased the mobility and decreased the resistivity of the deposited films. The 0 and 5 min delay times produced the silicon particle sizes of approximately 10 and approximately 28 nm, respectively, in the initial microstructure, which produced the final films, after deposition for 300 sec, of resistivities of 0.32 and 0.13 Omega-cm, mobilities of 1.06 and 1.48 cm2 V(-1) S(-1), and relative densities of 0.87 and 0.92, respectively.

  12. Cell adhesion response on femtosecond laser initiated liquid assisted silicon surface.

    PubMed

    Ulmeanu, M; Sima, L E; Ursescu, D; Enculescu, M; Bazan, X; Quintana, I

    2014-03-01

    Silicon substrates were irradiated at normal incidence with a femtosecond Ti:sapphire laser (Quatronix, 90 fs pulse duration, 1 kHz repetition rate, M(2) ~ 1.2, maximum energy peak 350 mJ ) operating at a wavelength of 400 nm and focused via a microscope objective (Newport; UV Objective Model, 37x 0.11 N.A.). The laser scanning was assisted by liquids precursors media such as methanol and 1,1,2-trichlorotrifluoroethane. By altering the processing parameters, such as incident laser energy, scanning speed, and different irradiation media, various surface structures were produced on areas with 1 mm(2) dimensions. We analyzed the dependence of the surface morphology on laser pulse energy, scanning speed and irradiation media. Well ordered areas are developed without imposing any boundary conditions for the capillary waves that coarsens the ripple pattern. To assess biomaterial-driven cell adhesion response we investigated actin filaments organization and cell morphological changes following growth onto processed silicon substrates. Our study of bone cell progenitor interaction with laser nanoprocessed silicon lines has shown that cells anchor mainly to contact points along the nanostructured surface. Consequently, actin filaments are stretched towards the 15 µm wide parallel lines increasing lateral cell spreading and changing the bipolar shape of mesenchymal stem cells.

  13. Computational Study of Field Initiated Surface Reactions for Synthesis of Diamond and Silicon

    NASA Technical Reports Server (NTRS)

    Musgrave, Charles Bruce

    1999-01-01

    This project involves using quantum chemistry to simulate surface chemical reactions in the presence of an electric field for nanofabrication of diamond and silicon. A field delivered by a scanning tunneling microscope (STM) to a nanometer scale region of a surface affects chemical reaction potential energy surfaces (PES) to direct atomic scale surface modification to fabricate sub-nanometer structures. Our original hypothesis is that the applied voltage polarizes the charge distribution of the valence electrons and that these distorted molecular orbitals can be manipulated with the STM so as to change the relative stabilities of the electronic configurations over the reaction coordinates and thus the topology of the PES and reaction kinetics. Our objective is to investigate the effect of applied bias on surface reactions and the extent to which STM delivered fields can be used to direct surface chemical reactions on an atomic scale on diamond and silicon. To analyze the fundamentals of field induced chemistry and to investigate the application of this technique for the fabrication of nanostructures, we have employed methods capable of accurately describing molecular electronic structure. The methods we employ are density functional theory (DFT) quantum chemical (QC) methods. To determine the effect of applied bias on surface reactions we have calculated the QC PESs in various applied external fields for various reaction steps for depositing or etching diamond and silicon. We have chosen reactions which are thought to play a role in etching and the chemical vapor deposition growth of Si and diamond. The PESs of the elementary reaction steps involved are then calculated under the applied fields, which we vary in magnitude and configuration. We pay special attention to the change in the reaction barriers, and transition state locations, and search for low energy reaction channels which were inaccessible without the applied bias.

  14. View from Silicon Valley: Maximizing the Scientific Impact of Global Brain Initiatives through Entrepreneurship.

    PubMed

    Joshi, Pushkar S; Ghosh, Kunal K

    2016-11-02

    In this era of technology-driven global neuroscience initiatives, the role of the neurotechnology industry remains woefully ambiguous. Here, we explain why industry is essential to the success of these global initiatives, and how it can maximize the scientific impact of these efforts by (1) scaling and ultimately democratizing access to breakthrough neurotechnologies, and (2) commercializing technologies as part of integrated, end-to-end solutions that accelerate neuroscientific discovery.

  15. Silicon Carbide Photoconductive Switches

    DTIC Science & Technology

    1994-09-01

    The optoelectronic properties of p-type 6-H silicon carbide (6H-SiC) have been investigated in an experiment that used lateral and vertical...and the bandgap was determined to be approximately 3.1 eV. 6H-SiC, Photoconductive, Photovoltaic, Absorption coefficient, Switch, Silicon carbide

  16. Effect of initial α-phase content on microstructure and flexural strength of macroporous silicon carbide ceramics

    NASA Astrophysics Data System (ADS)

    Eom, Jung-Hye; Kim, Young-Wook

    2012-04-01

    The effects of the initial α-phase content on the microstructure and flexural strength of macroporous silicon carbide (SiC) ceramics were investigated. When β powder or a mixture of α/β powders containing small (≤3%) amounts of α powder were used, the grains showed a platelet-shape. In contrast, the grains had an equiaxed-shape when α powder or a mixture of α/β powders containing large (≥50%) amounts of α powder was used. The flexural strength increased with increasing α-SiC content in the starting composition, whereas the porosity decreased with increasing α-SiC content. The strength of the macroporous SiC ceramics was affected mostly by the porosity when the grain size was smaller than 10 μm, whereas the strength was controlled by pore size and grain size when the microstructure consisted of large (>10 μm) platelet grains.

  17. Ensemble Monte Carlo calculation of the hole initiated impact ionization rate in bulk GaAs and silicon using a k-dependent, numerical transition rate formulation

    NASA Technical Reports Server (NTRS)

    Oguzman, Ismail H.; Wang, Yang; Kolnik, Jan; Brennan, Kevin F.

    1995-01-01

    The hole initiated impact ionization rate in bulk silicon and GaAs is calculated using a numerical formulation of the impact ionization transition rate incorporated into an ensemble Monte Carlo simulation. The transition rate is calculated from Fermi's golden rule using a two-body screened Coulomb interaction including a wavevector dependent dielectric function. It is found that the effective threshold for hole initiated ionization is relatively soft in both materials, that the split-off band dominates the ionization process in GaAs. and that no clear dominance by any one band is observed in silicon, though the rate out of the light hole band is greatest.

  18. Initial results of a silicon sensor irradiation study for ILC extreme forward calorimetry

    NASA Astrophysics Data System (ADS)

    Band, Reyer; Fadeyev, Vitaliy; Field, R. Clive; Key, Spencer; Kim, Tae Sung; Markiewicz, Thomas; Martinez-McKinney, Forest; Maruyama, Takashi; Mistry, Khilesh; Nidumolu, Ravi; Schumm, Bruce A.; Spencer, Edwin; Timlin, Conor; Wilder, Max

    2014-11-01

    Detectors proposed for the International Linear Collider (ILC) incorporate a tungsten sampling calorimeter ('BeamCal') intended to reconstruct showers of electrons, positrons and photons that emerge from the interaction point of the collider with angles between 5 and 50 milliradians. For the innermost radius of this calorimeter, radiation doses at shower-max are expected to reach 100 MRad per year, primarily due to minimum-ionizing electrons and positrons that arise in the induced electromagnetic showers of e+e- 'beamstrahlung' pairs produced in the ILC beam-beam interaction. However, radiation damage to calorimeter sensors may be dominated by hadrons induced by nuclear interactions of shower photons, which are much more likely to contribute to the non-ionizing energy loss that has been observed to damage sensors exposed to hadronic radiation. We report here on the results of SLAC Experiment T-506, for which several different types of silicon diode sensors were exposed to doses of radiation induced by showering electrons of energy 3.5-10.6 GeV. By embedding the sensor under irradiation within a tungsten radiator, the exposure incorporated hadronic species that would potentially contribute to the degradation of a sensor mounted in a precision sampling calorimeter. Depending on sensor technology, efficient charge collection was observed for doses as large as 220 MRad.

  19. [Prevention of postenucleation syndrome: the hydroxylapatite silicone implant. Preliminary experimental studies and initial clinical experiences].

    PubMed

    Guthoff, R; Vick, H P; Schaudig, U

    1995-04-01

    An orbital implant after enucleation compensates for volume deficiency and increases prosthesis motility. In the literature, however, an extrusion rate of orbital implant between 10 and 25% is reported. Since the introduction of hydroxylapatic ceramics (HAC), these numbers have been reduced considerably. The HAC, which is derived from corals, has a rough surface and requires a scleral covering for implantation. The HAC, which is made in the laboratory, can be produced with smoother surfaces, so that a homoplastic covering is no longer mandatory. A composite implant was developed to improve prosthesis motility further. This consists of artificial HAC at its anterior surface to guarantee safe tissue integration; the posterior part of the implant is manufactured from silicon rubber to create a jointlike structure in Tenon's capsule. Integration of the porous HAC in the orbital soft tissues has been tested and confirmed by animal experiments. After 30 full HAC implants and 25 composite implants, only one extrusion occurred. In all other cases, compatibility proved to be excellent; transmission of the motility to the prosthesis was moderate to good. Examinations comparing prosthesis motility and computer tomographically evaluated implant motility enabled the analysis of deficits in motility transmission of the implant for the artificial eye.

  20. Angular sensitivity of modeled scientific silicon charge-coupled devices to initial electron direction

    NASA Astrophysics Data System (ADS)

    Plimley, Brian; Coffer, Amy; Zhang, Yigong; Vetter, Kai

    2016-08-01

    Previously, scientific silicon charge-coupled devices (CCDs) with 10.5-μm pixel pitch and a thick (650 μm), fully depleted bulk have been used to measure gamma-ray-induced fast electrons and demonstrate electron track Compton imaging. A model of the response of this CCD was also developed and benchmarked to experiment using Monte Carlo electron tracks. We now examine the trade-off in pixel pitch and electronic noise. We extend our CCD response model to different pixel pitch and readout noise per pixel, including pixel pitch of 2.5 μm, 5 μm, 10.5 μm, 20 μm, and 40 μm, and readout noise from 0 eV/pixel to 2 keV/pixel for 10.5 μm pixel pitch. The CCD images generated by this model using simulated electron tracks are processed by our trajectory reconstruction algorithm. The performance of the reconstruction algorithm defines the expected angular sensitivity as a function of electron energy, CCD pixel pitch, and readout noise per pixel. Results show that our existing pixel pitch of 10.5 μm is near optimal for our approach, because smaller pixels add little new information but are subject to greater statistical noise. In addition, we measured the readout noise per pixel for two different device temperatures in order to estimate the effect of temperature on the reconstruction algorithm performance, although the readout is not optimized for higher temperatures. The noise in our device at 240 K increases the FWHM of angular measurement error by no more than a factor of 2, from 26° to 49° FWHM for electrons between 425 keV and 480 keV. Therefore, a CCD could be used for electron-track-based imaging in a Peltier-cooled device.

  1. Contact printing of horizontally-aligned p-type Zn₃P₂ nanowire arrays for rigid and flexible photodetectors.

    PubMed

    Yu, Gang; Liang, Bo; Huang, Hongtao; Chen, Gui; Liu, Zhe; Chen, Di; Shen, Guozhen

    2013-03-08

    Zn(3)P(2) is an important p-type semiconductor with the ability to detect almost all visible and ultraviolet light. By using the simple and efficient contact printing process, we reported the assembly of horizontally-aligned p-type Zn(3)P(2) nanowire arrays to be used as building blocks for high performance photodetectors. Horizontally-aligned Zn(3)P(2) nanowire arrays were first printed on silicon substrate to make thin-film transistors, exhibiting typical p-type transistor behavior with a high on/off ratio of 10(3). Besides, the Zn(3)P(2) nanowire array based devices showed a substantial response to illuminated lights with a wide range of wavelengths and densities. Flexible photodetectors were also fabricated by contact printing of horizontally-aligned Zn(3)P(2) nanowire arrays on flexible PET substrate, showing a comparable performance to the device on rigid silicon substrate.

  2. Plasticity initiation and evolution during nanoindentation of an iron-3% silicon crystal.

    PubMed

    Zhang, Ling; Ohmura, Takahito

    2014-04-11

    Our investigations confirm that the collective, avalanchelike dislocation nucleation and multiplication is responsible for the pop-in event in a body-centered-cubic Fe-3% Si single crystal. Dislocation was not observed prior to pop-in but was apparent after the event. We find that a transition from an initial stage dominated by discrete dislocation nucleation to subsequent continuum plasticity occurs just after the pop-in event as elastoplastic deformation ensues.

  3. Soft error rate simulation and initial design considerations of neutron intercepting silicon chip (NISC)

    NASA Astrophysics Data System (ADS)

    Celik, Cihangir

    -scale technologies. Prevention of SEEs has been studied and applied in the semiconductor industry by including radiation protection precautions in the system architecture or by using corrective algorithms in the system operation. Decreasing 10B content (20%of natural boron) in the natural boron of Borophosphosilicate glass (BPSG) layers that are conventionally used in the fabrication of semiconductor devices was one of the major radiation protection approaches for the system architecture. Neutron interaction in the BPSG layer was the origin of the SEEs because of the 10B (n,alpha) 7Li reaction products. Both of the particles produced have the capability of ionization in the silicon substrate region, whose thickness is comparable to the ranges of these particles. Using the soft error phenomenon in exactly the opposite manner of the semiconductor industry can provide a new neutron detection system based on the SERs in the semiconductor memories. By investigating the soft error mechanisms in the available semiconductor memories and enhancing the soft error occurrences in these devices, one can convert all memory using intelligent systems into portable, power efficient, directiondependent neutron detectors. The Neutron Intercepting Silicon Chip (NISC) project aims to achieve this goal by introducing 10B-enriched BPSG layers to the semiconductor memory architectures. This research addresses the development of a simulation tool, the NISC Soft Error Analysis Tool (NISCSAT), for soft error modeling and analysis in the semiconductor memories to provide basic design considerations for the NISC. NISCSAT performs particle transport and calculates the soft error probabilities, or SER, depending on energy depositions of the particles in a given memory node model of the NISC. Soft error measurements were performed with commercially available, off-the-shelf semiconductor memories and microprocessors to observe soft error variations with the neutron flux and memory supply voltage. Measurement

  4. 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.

  5. Spin-pump-induced spin transport in p-type Si at room temperature.

    PubMed

    Shikoh, Eiji; Ando, Kazuya; Kubo, Kazuki; Saitoh, Eiji; Shinjo, Teruya; Shiraishi, Masashi

    2013-03-22

    A spin battery concept is applied for the dynamical generation of pure spin current and spin transport in p-type silicon (p-Si). Ferromagnetic resonance and effective s-d coupling in Ni(80)Fe(20) results in spin accumulation at the Ni(80)Fe(20)/p-Si interface, inducing spin injection and the generation of spin current in the p-Si. The pure spin current is converted to a charge current by the inverse spin Hall effect of Pd evaporated onto the p-Si. This approach demonstrates the generation and transport of pure spin current in p-Si at room temperature.

  6. Spin-Pump-Induced Spin Transport in p-Type Si at Room Temperature

    NASA Astrophysics Data System (ADS)

    Shikoh, Eiji; Ando, Kazuya; Kubo, Kazuki; Saitoh, Eiji; Shinjo, Teruya; Shiraishi, Masashi

    2013-03-01

    A spin battery concept is applied for the dynamical generation of pure spin current and spin transport in p-type silicon (p-Si). Ferromagnetic resonance and effective s-d coupling in Ni80Fe20 results in spin accumulation at the Ni80Fe20/p-Si interface, inducing spin injection and the generation of spin current in the p-Si. The pure spin current is converted to a charge current by the inverse spin Hall effect of Pd evaporated onto the p-Si. This approach demonstrates the generation and transport of pure spin current in p-Si at room temperature.

  7. Compensated amorphous silicon solar cell

    DOEpatents

    Carlson, David E.

    1980-01-01

    An amorphous silicon solar cell incorporates a region of intrinsic hydrogenated amorphous silicon fabricated by a glow discharge wherein said intrinsic region is compensated by P-type dopants in an amount sufficient to reduce the space charge density of said region under illumination to about zero.

  8. 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.

  9. 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.

  10. 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.

  11. Methodologies in Search of p-type Transparent Conductors

    NASA Astrophysics Data System (ADS)

    Lam, Kanber

    P-type transparent conductors are rare in nature but could lead to a lot technological innovations. A systematic search for p-type transparent conductors can be divided into two types: to search for (I) experimentally unknown compounds and (II) experimentally known ones. The difference between the two types of search lies in the fact that we always start with the experimental crystal structure in type II search while such information is lacking in the type I search. To make the type I research possible, a reasonably efficient method in predicting the ground state crystal structure is required. And the evolutionary algorithm with the real-space cut-and-splice method is a promising candidate for the task. For both type I and type II searches, we have to accurately predict the fundamental band gap and the hole conductivity. Corrections to density functional theory band gap, such as screened exchange LDA (sxLDA) or G0W0 , are required. The hole conductivity is linearly dependent on the hole concentration and inversely proportional to the hole effective mass. And we focused on the study of host material properties, the fundamental band gaps and hole effective masses, in the oxide sulfide family and eight promising candidates as p-type transparent conducting hosts were found. The hole population in the known transparent conducting oxides (TCOs) is mostly orig- inating from intrinsic point defects. However, a material La5Cu6O4S7 , whose hole conduc- tivity is an order of magnitude higher than the known TCOs, has its holes originating from a line structure, namely the breaking of dimers on the sulfur chain. The sulfur chain is optically inactive and serves purely to generate holes traveling in the Cu6S6 layers at finite temperature. This interesting hole-generating mechanism could open up new possibilities to achieve high hole conductivity in p-type TCs.

  12. DLTS of p-type Czochralski Si wafers containing processing-induced macropores

    NASA Astrophysics Data System (ADS)

    Simoen, E.; Depauw, V.; Gordon, I.; Poortmans, J.

    2012-01-01

    The deep levels present in p-type Czochralski silicon with processing-induced macropores in the depletion region have been studied by the deep-level transient (DLT) spectroscopy technique. It is shown that a broad band is present for a bias pulse close to the interface with the Al Schottky contact, which exhibits anomalously slow hole capture and is ascribed to the internal interface states of the macropores. For depths beyond the pore region, other deep levels, associated with point defects—possibly metal contamination during the high-temperature annealing step under H2 ambient--have been observed. The impact of the observed defects on the lifetime of thin-film solar cells, fabricated using macropore-based layer transfer is discussed. Finally, it is shown that the presence of pores in the depletion region, which also affects the DLT-spectrum, alters the capacitance-voltage characteristics.

  13. Microwave Induced Direct Bonding of Single Crystal Silicon Wafers

    NASA Technical Reports Server (NTRS)

    Budraa, N. K.; Jackson, H. W.; Barmatz, M.

    1999-01-01

    We have heated polished doped single-crystal silicon wafers in a single mode microwave cavity to temperatures where surface to surface bonding occurred. The absorption of microwaves and heating of the wafers is attributed to the inclusion of n-type or p-type impurities into these substrates. A cylindrical cavity TM (sub 010) standing wave mode was used to irradiate samples of various geometry's at positions of high magnetic field. This process was conducted in vacuum to exclude plasma effects. This initial study suggests that the inclusion of impurities in single crystal silicon significantly improved its microwave absorption (loss factor) to a point where heating silicon wafers directly can be accomplished in minimal time. Bonding of these substrates, however, occurs only at points of intimate surface to surface contact. The inclusion of a thin metallic layer on the surfaces enhances the bonding process.

  14. 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

    2014-11-07

    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.

  15. 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.

  16. 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.

  17. 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.

  18. Total Ionizing Dose Radiation Effects in the P-Type Polycrystalline Silicon Thin Film Transistors

    NASA Astrophysics Data System (ADS)

    Liu, Yuan; Liu, Kai; Chen, Rong-Sheng; Liu, Yu-Rong; En, Yun-Fei; Li, Bin; Fang, Wen-Xiao

    2017-01-01

    Not Available Supported by the National Natural Science Foundation of China under Grant Nos 61574048 and 61204112, the Science and Technology Research Project of Guangdong Province under Grant Nos 2015B090912002 and 2014A030313656, and the Pearl River S&T Nova Program of Guangzhou.

  19. Thermal and electromechanical characterization of top-down fabricated p-type silicon nanowires

    NASA Astrophysics Data System (ADS)

    Bosseboeuf, Alain; Allain, Pierre Etienne; Parrain, Fabien; Le Roux, Xavier; Isac, Nathalie; Jacob, Serge; Poizat, Alexis; Coste, Philippe; Maaroufi, Seiffedine; Walther, Arnaud

    2015-01-01

    In this paper we report thermal conductivity and piezoresistivity measurements of top-down fabricated highly boron doped (NA = 1.5 × 1019 cm-3) suspended Si nanowires. These measurements were performed in a cryogenic probe station respectively by using the 3 omega method and by in situ application of a longitudinal tensile stress to the nanowire under test with a direct four point bending of the Si nanowire die. Nanowires investigated have a thickness of 160 nm, a width in the 80-260 nm range and a length in the 2.5-5.2 μm range. We found that for these geometries, thermal conduction still obeys Fourier’s law and that, as expected, the thermal conductivity is largely reduced when the nanowires width is shrunk, but, to a lower extent than published values for nanowires grown by vapor-liquid-solid (VLS) processes. While a large giant piezoresistance effect was evidenced by various authors when a static stress is applied, we only observed a limited nanowire size dependence of the piezoresistivity in our experiments where a dynamical mechanical loading is applied. This confirms that the giant piezoresistance effect in unbiased Si nanowires is not an intrinsic bulk effect but is dominated by surface related effects in agreement with the piezopinch effect model. Invited talk at the 7th International Workshop on Advanced Materials Science and Nanotechnology IWAMSN2014, 2-6 November, 2014, Ha Long, Vietnam

  20. 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.

  1. Complementary X-ray and neutron radiography study of the initial lithiation process in lithium-ion batteries containing silicon electrodes

    NASA Astrophysics Data System (ADS)

    Sun, Fu; Markötter, Henning; Manke, Ingo; Hilger, André; Alrwashdeh, Saad S.; Kardjilov, Nikolay; Banhart, John

    2017-03-01

    Complementary in operando X-ray radiography and neutron radiography measurements were conducted to investigate and visualize the initial lithiation in silicon-electrode lithium-ion batteries. By means of X-ray radiography, a significant volume expansion of Si particles and the Si electrode during the first discharge was observed. In addition, many Si particles were found that never undergo electrochemical reactions. These findings were confirmed by neutron radiography, which, for the first time, showed the process of Li alloying with the Si electrode during initial lithiation. These results demonstrate that complementary X-ray and neutron radiography is a powerful tool to investigate the lithiation mechanisms inside Si-electrode based lithium-ion batteries.

  2. 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.

  3. Method and apparatus for stable silicon dioxide layers on silicon grown in silicon nitride ambient

    NASA Technical Reports Server (NTRS)

    Cohen, R. A.; Wheeler, R. K. (Inventor)

    1974-01-01

    A method and apparatus for thermally growing stable silicon dioxide layers on silicon is disclosed. A previously etched and baked silicon nitride tube placed in a furnace is used to grow the silicon dioxide. First, pure oxygen is allowed to flow through the tube to initially coat the inside surface of the tube with a thin layer of silicon dioxide. After the tube is coated with the thin layer of silicon dioxide, the silicon is oxidized thermally in a normal fashion. If the tube becomes contaminated, the silicon dioxide is etched off thereby exposing clean silicon nitride and then the inside of the tube is recoated with silicon dioxide. As is disclosed, the silicon nitride tube can also be used as the ambient for the pyrolytic decomposition of silane and ammonia to form thin layers of clean silicon nitride.

  4. Oxychalcogenides as New Efficient p-TYPE Thermoelectric Materials

    NASA Astrophysics Data System (ADS)

    Barreteau, Celine; Pan, Lin; Pei, Yan-Ling; Zhao, Li-Dong; Berardan, David; Dragoe, Nita

    2013-07-01

    During the past two years, we have underlined the great potential of p-type oxychalcogenides, with parent compound BiCuSeO, for thermoelectric applications in the medium temperature range (400-650°C). These materials, which do not contain lead and are less expensive than Te containing materials, exhibit large thermoelectric figure of merit, exceeding 1 in a wide temperature range, mainly due to an intrinsically very low thermal conductivity. This paper summarizes the main chemical and crystallographic features of this system, as well as the thermoelectric properties. It also gives new directions to improve these properties, and discuss the potential of these materials for wide scale applications in thermoelectric conversion system in the medium temperature range.

  5. Experiments with semiconducting p-type misfit compound

    NASA Astrophysics Data System (ADS)

    Heinonen, H.; Tervo, J.

    2012-06-01

    Ca3Co4O9 is a p-type semiconductor and a promising thermoelectric material with misfit layer structure. Cobalt-based layered structure materials have been studied as thermoelectric material candidates because of their nontoxicity, light weight, high thermal and chemical stability and oxidation resistance at high temperature. The operating area of Ca3Co4O9 in thermoelectric applications is roughly from 800K to 1000K. Ca3Co4O9 powders were synthetized by a sol-gel method which enables fabrication of high purity and homogeneous particles. Calcium and cobalt nitrate hydrates were used as feedstock and citric acid as complexing agent in the sol-gel procedure. Powders were calcinated at 1123K and further processing by ball milling. Pure Ca3Co4O9 powders were sintered by SPS and conventional method.

  6. What are the P-type Asteroids Made Of?

    NASA Technical Reports Server (NTRS)

    Hiroi, T.; Pieters, C. M.; Rutherford, M. J.; Zolensky, M. E.; Sasaki, S.; Ueda, Y.; Miyamoto, M.

    2004-01-01

    The P-type asteroids, together with the D asteroids, had been believed to be one of the most primitive asteroid classes having surface materials rich in carbon and/or organics. Upon a fall of a new type of meteorite, Tagish Lake in 2000, we came to have a possible sample of the D (and/or T) asteroids. In both spectrally and distance from the sun, the P asteroids are located in between the C/G/B/F asteroids and the D asteroids. Because it is believed that the former group are similar to (thermally metamorphosed) CI/CM chondrites and the latter the Tagish Lake meteorite, the surface material of the P asteroids may be understood in combination of those two meteorite groups. Taking that direction, this paper presents possibly the first quantitative characterization of the P asteroids in terms of carbonaceous chondrites and their experimental derivatives.

  7. 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.

  8. Challenges in p-type Doping of CdTe

    NASA Astrophysics Data System (ADS)

    McCoy, Jedidiah; Swain, Santosh; Lynn, Kelvin

    We have made progress in defect identification of arsenic and phosphorous doped CdTe to understand the self-compensation mechanism which will help improve minority bulk carrier lifetime and net acceptor density. Combining previous measurements of un-doped CdTe, we performed a systematic comparison of defects between different types of crystals and confirmed the defects impacting the doping efficiency. CdTe bulk crystals have been grown via vertical Bridgman based melt growth technique with varying arsenic and phosphorous dopant schemes to attain p-type material. Furnace temperature profiles were varied to influence dopant solubility. Large carrier densities have been reproducibly obtained from these boules indicating successful incorporation of dopants into the lattice. However, these values are orders of magnitude lower than theoretical solubility values. Infrared Microscopy has revealed a plethora of geometrically abnormal second phase defects and X-ray Fluorescence has been used to identify the elemental composition of these defects. We believe that dopants become incorporated into these second phase defects as Cd compounds which act to inhibit dopant solubility in the lattice.

  9. Magnetic Incommensurability in p-TYPE Cuprate Perovskites

    NASA Astrophysics Data System (ADS)

    Sherman, A.

    2012-07-01

    For the superconducting phase with a d-wave order parameter and zero temperature, the magnetic susceptibility of the t-J model is calculated using the Mori projection operator technique. Conditions for the appearance of an incommensurate magnetic response below the resonance frequency are identified. A fast decay of the tails of the hole coherent peaks and a weak intensity of the hole incoherent continuum near the Fermi level are enough to produce an incommensurate response using different hole dispersions established for p-type cuprates, in which such response was observed. In this case, the nesting of the itinerant-electron theory or the charge modulation of the stripe theory is unnecessary for the incommensurability. The theory reproduces the hourglass dispersion of the susceptibility maxima with their location in the momentum space similar to that observed experimentally. The upper branch of the dispersion stems from the excitations of localized spins, while the lower one is due to the incommensurate maxima of their damping. The narrow and intensive resonance peak arises if the frequency of these excitations at the antiferromagnetic momentum lies below the edge of the two-fermion continuum; otherwise the maximum is broad and less intensive.

  10. Electronic processes in uniaxially stressed p-type germanium

    SciTech Connect

    Dubon, Jr., Oscar Danilo

    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.

  11. Influence of experimental parameters on physical properties of porous silicon and oxidized porous silicon layers

    NASA Astrophysics Data System (ADS)

    Charrier, J.; Alaiwan, V.; Pirasteh, P.; Najar, A.; Gadonna, M.

    2007-08-01

    This paper reports physical properties of porous silicon and oxidized porous silicon, manufactured by anodisation from heavily p-type doped silicon wafers as a function of experimental parameters. The growth rate and refractive index of the layers were studied at different applied current densities and glycerol concentrations in electrolyte. When the current density varied from 5 to 100 mA/cm 2, the refractive index was between 1.2 and 2.4 which corresponded to a porosity range from 42 to 85%. After oxidation, the porosity decreased and was between 2 and 45% for a refractive index range from 1.22 to 1.46. The thermal processing also induced an increase in thickness which was dependent on the initial porosity. This increase in thickness was more important for the lowest porosities. Lastly, the roughness of the porous layer/silicon substrate interface was studied at different applied current densities and glycerol concentrations in solution. Roughness decreased when the current density or glycerol concentration increased. Moreover, roughness was also reduced by thermal oxidation.

  12. Stress effects on the initial lithiation of crystalline silicon nanowires: Reactive molecular dynamics simulations using ReaxFF

    SciTech Connect

    Ostadhossein, Alireza; Cubuk, Ekin D.; Tritsaris, Georgios A.; Kaxiras, Efthimios; Zhang, Sulin; Adri C. T. van Duin

    2014-12-18

    Silicon (Si) has been recognized as a promising anode material for the next-generation high-capacity lithium (Li)-ion batteries because of its high theoretical energy density. Recent in situ transmission electron microscopy (TEM) revealed that the electrochemical lithiation of crystalline Si nanowires (c-SiNWs) proceeds by the migration of the interface between the lithiated Si (LixSi) shell and the pristine unlithiated core, accompanied by solid-state amorphization. The underlying atomic mechanisms of Li insertion into c-Si remain poorly understood. In this research, we perform molecular dynamics (MD) simulations using the reactive force field (ReaxFF) to characterize the lithiation process of c-SiNWs. Our calculations show that ReaxFF can accurately reproduce the energy barriers of Li migration from DFT calculations in both crystalline (c-Si) and amorphous Si (a-Si). The ReaxFF-based MD simulations reveal that Li insertion into interlayer spacing between two adjacent (111) planes results in the peeling-off of the (111) facets and subsequent amorphization, in agreement with experimental observations. We find that breaking of the Si–Si bonds between (111)-bilayers requires a rather high local Li concentration, which explains the atomically sharp amorphous–crystalline interface (ACI). Our stress analysis shows that lithiation induces compressive stress at the ACI layer, causing retardation or even the stagnation of the reaction front, also in good agreement with TEM observations. Lithiation at high temperatures (e.g. 1200 K) shows that Li insertion into c-SiNW results in an amorphous to crystalline phase transformation at Li : Si composition of ~4.2:1. In conclusion, our modeling results provide a comprehensive picture of the effects of reaction and diffusion-induced stress on the interfacial dynamics and mechanical degradation of SiNW anodes under chemo-mechanical lithiation.

  13. Stress effects on the initial lithiation of crystalline silicon nanowires: Reactive molecular dynamics simulations using ReaxFF

    DOE PAGES

    Ostadhossein, Alireza; Cubuk, Ekin D.; Tritsaris, Georgios A.; ...

    2014-12-18

    Silicon (Si) has been recognized as a promising anode material for the next-generation high-capacity lithium (Li)-ion batteries because of its high theoretical energy density. Recent in situ transmission electron microscopy (TEM) revealed that the electrochemical lithiation of crystalline Si nanowires (c-SiNWs) proceeds by the migration of the interface between the lithiated Si (LixSi) shell and the pristine unlithiated core, accompanied by solid-state amorphization. The underlying atomic mechanisms of Li insertion into c-Si remain poorly understood. In this research, we perform molecular dynamics (MD) simulations using the reactive force field (ReaxFF) to characterize the lithiation process of c-SiNWs. Our calculations showmore » that ReaxFF can accurately reproduce the energy barriers of Li migration from DFT calculations in both crystalline (c-Si) and amorphous Si (a-Si). The ReaxFF-based MD simulations reveal that Li insertion into interlayer spacing between two adjacent (111) planes results in the peeling-off of the (111) facets and subsequent amorphization, in agreement with experimental observations. We find that breaking of the Si–Si bonds between (111)-bilayers requires a rather high local Li concentration, which explains the atomically sharp amorphous–crystalline interface (ACI). Our stress analysis shows that lithiation induces compressive stress at the ACI layer, causing retardation or even the stagnation of the reaction front, also in good agreement with TEM observations. Lithiation at high temperatures (e.g. 1200 K) shows that Li insertion into c-SiNW results in an amorphous to crystalline phase transformation at Li : Si composition of ~4.2:1. In conclusion, our modeling results provide a comprehensive picture of the effects of reaction and diffusion-induced stress on the interfacial dynamics and mechanical degradation of SiNW anodes under chemo-mechanical lithiation.« less

  14. P-type Ca2+ current in crayfish peptidergic neurones.

    PubMed

    GarcÍA-Colunga; Valdiosera; GarcÍA

    1999-01-21

    Inward Ca2+ current through voltage-gated Ca2+ channels was recorded from freshly dissociated crayfish X-organ (XO) neurones using the whole-cell voltage-clamp technique. Changing the holding potential from -50 to -90 mV had little effect on the characteristics of the current-voltage relationship: neither the time course nor the amplitude of the Ca2+ current was affected. Inactivation of the Ca2+ current was observed over a small voltage range, between -35 and -10 mV, with half-inactivation at -20 mV. The activation of the Ca2+ current was modelled using Hodgkin-Huxley kinetics. The time constant of activation, &tgr; m, was 568+/-66 micros at -20 mV and decreased gradually to 171+/-23 micros at 40 mV (means +/- s.e.m., N=5). The steady-state activation, m(infinity), was fitted with a Boltzmann function, with a half-activation voltage of -7.45 mV and an apparent threshold at -40 mV. The instantaneous current-voltage relationship was adjusted using the Goldman-Hodgkin-Katz constant-field equation, giving a permeation of 4.95x10(-5 )cm s-1. The inactivation of the Ca2+ current in XO neurones was dependent on previous entry of Ca2+. Using a double-pulse protocol, the inactivation was fitted to a U-shaped curve with a maximal inactivation of 35 % at 30 mV. The time course of the recovery from inactivation was fitted with an exponential function. The time constants were 17+/-2.6 ms for a prepulse of 10 ms and 31+/-3.2 ms for a prepulse of 20 ms. The permeability sequence of the Ca2+ channels was as follows: Ba2+>Sr2+~Ca2+>Mg2+. Other divalent cations blocked the Ca2+ current, and their effects were voltage-dependent; the potency of blockage was Cd2+~Zn2+>Co2+~Ni2+. The peptide &ohgr; -agatoxin-IVA, a selective toxin for P-type Ca2+ channels, blocked 85 % of the Ca2+ current in XO neurones at 200 nmol l-1, but the current was insensitive to dihydropyridines, phenylalkylamines, &ohgr; -conotoxin-GVIA and &ohgr; -conotoxin-MVIIC, which are blockers of L-, N- and Q-type Ca2

  15. 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.

  16. 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.

  17. 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

  18. 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

    2016-06-28

    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.

  19. 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.

  20. 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.

  1. Ultrafast hole carrier relaxation dynamics in p-type CuO nanowires

    PubMed Central

    2011-01-01

    Ultrafast hole carrier relaxation dynamics in CuO nanowires have been investigated using transient absorption spectroscopy. Following femtosecond pulse excitation in a non-collinear pump-probe configuration, a combination of non-degenerate transmission and reflection measurements reveal initial ultrafast state filling dynamics independent of the probing photon energy. This behavior is attributed to the occupation of states by photo-generated carriers in the intrinsic hole region of the p-type CuO nanowires located near the top of the valence band. Intensity measurements indicate an upper fluence threshold of 40 μJ/cm2 where carrier relaxation is mainly governed by the hole dynamics. The fast relaxation of the photo-generated carriers was determined to follow a double exponential decay with time constants of 0.4 ps and 2.1 ps. Furthermore, time-correlated single photon counting measurements provide evidence of three exponential relaxation channels on the nanosecond timescale. PMID:22151927

  2. Microgravity silicon zoning investigation

    NASA Technical Reports Server (NTRS)

    Kern, E. L.; Gill, G. L., Jr.

    1983-01-01

    A resistance heated zoner, suitable for early zoning experiments with silicon, was designed and put into operation. The initial power usage and size was designed for an shown to be compatible with payload carriers contemplated for the Shuttle. This equipment will be used in the definition and development of flight experiments and apparatus for float zoning silicon and other materials in microgravity.

  3. Enhanced in-plane thermoelectric figure of merit in p-type SiGe thin films by nanograin boundaries

    NASA Astrophysics Data System (ADS)

    Lu, Jianbiao; Guo, Ruiqiang; Dai, Weijing; Huang, Baoling

    2015-04-01

    P-Type polycrystalline silicon-germanium (SiGe) thin films are grown by low-pressure chemical vapor deposition (LPCVD) and their thermoelectric properties are characterized from 120 K to 300 K for potential application in integrated microscale cooling. The naturally formed grain boundaries are found to play a crucial role in determining both the charge and thermal transport properties of the films. Particularly, the grain boundaries create energy barriers for charge transport which lead to different dependences of charge mobility on doping concentration and temperature from the bulk counterparts. Meanwhile, the unique columnar grain structures result in remarkable thermal conductivity anisotropy with the in-plane thermal conductivities of SiGe films about 50% lower than the cross-plane values. By optimizing the growth conditions and doping level, a high in-plane figure of merit (ZT) of 0.2 for SiGe films is achieved at 300 K, which is about 100% higher than the previous record for p-type SiGe alloys, mainly due to the significant reduction in the in-plane thermal conductivity caused by nanograin boundaries. The low cost and excellent scalability of LPCVD render these high-performance SiGe films ideal candidates for thin-film thermoelectric applications.P-Type polycrystalline silicon-germanium (SiGe) thin films are grown by low-pressure chemical vapor deposition (LPCVD) and their thermoelectric properties are characterized from 120 K to 300 K for potential application in integrated microscale cooling. The naturally formed grain boundaries are found to play a crucial role in determining both the charge and thermal transport properties of the films. Particularly, the grain boundaries create energy barriers for charge transport which lead to different dependences of charge mobility on doping concentration and temperature from the bulk counterparts. Meanwhile, the unique columnar grain structures result in remarkable thermal conductivity anisotropy with the in

  4. Schottky barrier amorphous silicon solar cell with thin doped region adjacent metal Schottky barrier

    DOEpatents

    Carlson, David E.; Wronski, Christopher R.

    1979-01-01

    A Schottky barrier amorphous silicon solar cell incorporating a thin highly doped p-type region of hydrogenated amorphous silicon disposed between a Schottky barrier high work function metal and the intrinsic region of hydrogenated amorphous silicon wherein said high work function metal and said thin highly doped p-type region forms a surface barrier junction with the intrinsic amorphous silicon layer. The thickness and concentration of p-type dopants in said p-type region are selected so that said p-type region is fully ionized by the Schottky barrier high work function metal. The thin highly doped p-type region has been found to increase the open circuit voltage and current of the photovoltaic device.

  5. P-type Planet–Planet Scattering: Kepler Close Binary Configurations

    NASA Astrophysics Data System (ADS)

    Gong, Yan-Xiang

    2017-01-01

    A hydrodynamical simulation shows that a circumbinary planet will migrate inward to the edge of the disk cavity. If multiple planets form in a circumbinary disk, successive migration will lead to planet–planet scattering (PPS). PPS of Kepler-like circumbinary planets is discussed in this paper. The aim of this paper is to answer how PPS affects the formation of these planets. We find that a close binary has a significant influence on the scattering process. If PPS occurs near the unstable boundary of a binary, about 10% of the systems can be completely destroyed after PPS. In more than 90% of the systems, there is only one planet left. Unlike the eccentricity distribution produced by PPS in a single star system, the surviving planets generally have low eccentricities if PPS take place near the location of the currently found circumbinary planets. In addition, the ejected planets are generally the innermost of two initial planets. The above results depend on the initial positions of the two planets. If the initial positions of the planets are moved away from the binary, the evolution tends toward statistics similar to those around single stars. In this process, the competition between the planet–planet force and the planet-binary force makes the eccentricity distribution of surviving planets diverse. These new features of P-type PPS will deepen our understanding of the formation of these circumbinary planets.

  6. 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.

  7. Silicon germanium carbon heteroepitaxial growth on silicon

    NASA Astrophysics Data System (ADS)

    Mayer, James W.

    1993-10-01

    This project represents the initiation of band-gap engineering of Si-based devices at Arizona State University by James W. Mayer. While at Cornell, he directed the Microscience and Technology program supported by the Semiconductor Research Corporation. His Work on heteoepitaxy of SiGe on silicon convinced him that heteroepitaxy on Si was a viable technique for forming smaller band gap layers on silicon but the requirement was for larger energy-gap materials. In the fall of 1991, James Mayer visited Tom Picraux of Sandia National Laboratories and Clarence Tracy of Motorola Semiconductor Products to discuss the possibility of a joint program to investigate Silicon Germanium Carbon Heteroepitaxial Growth on Silicon. This represented a new research and development initiate for band gap engineering.

  8. Silicone metalization

    SciTech Connect

    Maghribi, Mariam N.; Krulevitch, Peter; Hamilton, Julie

    2008-12-09

    A system for providing metal features on silicone comprising providing a silicone layer on a matrix and providing a metal layer on the silicone layer. An electronic apparatus can be produced by the system. The electronic apparatus comprises a silicone body and metal features on the silicone body that provide an electronic device.

  9. Silicone metalization

    SciTech Connect

    Maghribi, Mariam N.; Krulevitch, Peter; Hamilton, Julie

    2006-12-05

    A system for providing metal features on silicone comprising providing a silicone layer on a matrix and providing a metal layer on the silicone layer. An electronic apparatus can be produced by the system. The electronic apparatus comprises a silicone body and metal features on the silicone body that provide an electronic device.

  10. Atomic scale investigation of silicon nanowires and nanoclusters

    PubMed Central

    2011-01-01

    In this study, we have performed nanoscale characterization of Si-clusters and Si-nanowires with a laser-assisted tomographic atom probe. Intrinsic and p-type silicon nanowires (SiNWs) are elaborated by chemical vapor deposition method using gold as catalyst, silane as silicon precursor, and diborane as dopant reactant. The concentration and distribution of impurity (gold) and dopant (boron) in SiNW are investigated and discussed. Silicon nanoclusters are produced by thermal annealing of silicon-rich silicon oxide and silica multilayers. In this process, atom probe tomography (APT) provides accurate information on the silicon nanoparticles and the chemistry of the nanolayers. PMID:21711788

  11. Porous silicon nanoparticle as a stabilizing support for chondroitinase.

    PubMed

    Daneshjou, Sara; Dabirmanesh, Bahareh; Rahimi, Fereshteh; Khajeh, Khosro

    2017-01-01

    Chondroitinase ABCI (cABCI) from Proteus vulgaris is a drug enzyme that can be used to treat spinal cord injuries. One of the main problems of chondroitinase ABC1 is its low thermal stability. The objective of the current study was to stabilize the enzyme through entrapment within porous silicon (pSi) nanoparticles. pSi was prepared by an electrochemical etch of p-type silicon using hydrofluoric acid/ethanol. The size of nanoparticles were determined 180nm by dynamic light scattering and the mean pore diameter was in the range of 40-60nm obtained by scanning electron microscopy. Enzymes were immobilized on porouse silicon nanoparticles by entrapment. The capacity of matrix was 35μg enzyme per 1mg of silicon. The immobilized enzyme displayed lower Vmax values compared to the free enzyme, but Km values were the same for both enzymes. Immobilization significantly increased the enzyme stability at various temperatures (-20, 4, 25 and 37°C). For example, at 4°C, the free enzyme (in 10mM imidazole) retained 20% of its activity after 100min, while the immobilized one retained 50% of its initial activity. Nanoparticles loading capacity and the enzyme release rate showed that the selected particles could be a pharmaceutically acceptable carrier for chondroitinase.

  12. Photovoltaic Cell Having A P-Type Polycrystalline Layer With Large Crystals

    DOEpatents

    Albright, Scot P.; Chamberlin, Rhodes R.

    1996-03-26

    A photovoltaic cell has an n-type polycrystalline layer and a p-type polycrystalline layer adjoining the n-type polycrystalline layer to form a photovoltaic junction. The p-type polycrystalline layer comprises a substantially planar layer portion having relatively large crystals adjoining the n-type polycrystalline layer. The planar layer portion includes oxidized impurities which contribute to obtainment of p-type electrical properties in the planar layer portion.

  13. Fabrication and characterization of p-type SiNW/n-type ZnO heterostructure for optoelectronics application

    NASA Astrophysics Data System (ADS)

    Hazra, Purnima; Chakrabarti, P.; Jit, S.

    2015-02-01

    Semiconductor hybrid structure, known as core-shell heterostructures was fabricated and optical properties were analyzed to make it applicable in future optoelectronic and photonic devices. Large-area, high density, vertically oriented silicon nanowire arrays, synthesized by means of metal-assisted chemical etching of p-type silicon (100) substrate was used as the core and zinc oxide (ZnO) layer, deposited on the SiNW arrays by atomic layer deposition (ALD) was used as shell. The XRD peaks of the heterostructure confirmed the subsequent growth of ZnO film on the template of SiNW arrays having similar crystalline quality. The photoluminescence (PL) spectra showed a very sharp peak at 378 nm, corresponding to the band gap of ZnO material and another broad emission band almost throughout the entire visible range with a peak around 550 nm. The structure also showed a very good antireflection property. The results present that the SiNW/ZnO heterostructure can have potential application in future nanoscale electronic and photonic devices.

  14. Ultra-thin ohmic contacts for p-type nitride light emitting devices

    DOEpatents

    Raffetto, Mark [Raleigh, NC; Bharathan, Jayesh [Cary, NC; Haberern, Kevin [Cary, NC; Bergmann, Michael [Chapel Hill, NC; Emerson, David [Chapel Hill, NC; Ibbetson, James [Santa Barbara, CA; Li, Ting [Ventura, CA

    2012-01-03

    A semiconductor based Light Emitting Device (LED) can include a p-type nitride layer and a metal ohmic contact, on the p-type nitride layer. The metal ohmic contact can have an average thickness of less than about 25 .ANG. and a specific contact resistivity less than about 10.sup.-3 ohm-cm.sup.2.

  15. Nanocrystalline silicon/amorphous silicon dioxide superlattices

    SciTech Connect

    Fauchet, P.M.; Tsybeskov, L.; Zacharias, M. |; Hirschman, K. |

    1998-12-31

    Thin layers made of densely packed silicon nanocrystals sandwiched between amorphous silicon dioxide layers have been manufactured and characterized. An amorphous silicon/amorphous silicon dioxide superlattice is first grown by CVD or RF sputtering. The a-Si layers are recrystallized in a two-step procedure (nucleation + growth) for form layers of nearly identical nanocrystals whose diameter is given by the initial a-Si layer thickness. The recrystallization is monitored using a variety of techniques, including TEM, X-Ray, Raman, and luminescence spectroscopies. When the a-Si layer thickness decreases (from 25 nm to 2.5 nm) or the a-SiO{sub 2} layer thickness increases (from 1.5 nm to 6 nm), the recrystallization temperature increases dramatically compared to that of a single a-Si film. The removal of the a-Si tissue present between the nanocrystals, the passivation of the nanocrystals, and their doping are discussed.

  16. Luminance behavior of lithium-doped ZnO nanowires with p-type conduction characteristics.

    PubMed

    Ko, Won Bae; Lee, Jun Seok; Lee, Sang Hyo; Cha, Seung Nam; Sohn, Jung Inn; Kim, Jong Min; Park, Young Jun; Kim, Hyun Jung; Hong, Jin Pyo

    2013-09-01

    The present study describes the room-temperature cathodeluminescence (CL) and temperature-dependent photoluminescence (PL) properties of p-type lithium (Li)-doped zinc oxide (ZnO) nanowires (NWs) grown by hydrothermal doping and post-annealing processes. A ZnO thin film was used as a seed layer in NW growth. The emission wavelengths and intensities of undoped ZnO NWs and p-type Li-doped ZnO NWs were analyzed for comparison. CL and PL observations of post-annealed p-type Li-doped ZnO NWs clearly exhibited a dominant sharp band-edge emission. Finally, a n-type ZnO thin film/p-type annealed Li-doped ZnO NW homojunction diode was prepared to confirm the p-type conduction of annealed Li-doped ZnO NWs as well as the structural properties measured by transmission electron microscopy.

  17. p-type Mesoscopic nickel oxide/organometallic perovskite heterojunction solar cells.

    PubMed

    Wang, Kuo-Chin; Jeng, Jun-Yuan; Shen, Po-Shen; Chang, Yu-Cheng; Diau, Eric Wei-Guang; Tsai, Cheng-Hung; Chao, Tzu-Yang; Hsu, Hsu-Cheng; Lin, Pei-Ying; Chen, Peter; Guo, Tzung-Fang; Wen, Ten-Chin

    2014-04-23

    In this article, we present a new paradigm for organometallic hybrid perovskite solar cell using NiO inorganic metal oxide nanocrystalline as p-type electrode material and realized the first mesoscopic NiO/perovskite/[6,6]-phenyl C61-butyric acid methyl ester (PC61BM) heterojunction photovoltaic device. The photo-induced transient absorption spectroscopy results verified that the architecture is an effective p-type sensitized junction, which is the first inorganic p-type, metal oxide contact material for perovskite-based solar cell. Power conversion efficiency of 9.51% was achieved under AM 1.5 G illumination, which significantly surpassed the reported conventional p-type dye-sensitized solar cells. The replacement of the organic hole transport materials by a p-type metal oxide has the advantages to provide robust device architecture for further development of all-inorganic perovskite-based thin-film solar cells and tandem photovoltaics.

  18. Photo-EMF sensitivity of porous silicon thin layer-crystalline silicon heterojunction to ammonia adsorption.

    PubMed

    Vashpanov, Yuriy; Jung, Jae Il; Kwack, Kae Dal

    2011-01-01

    A new method of using photo-electromotive force in detecting gas and controlling sensitivity is proposed. Photo-electromotive force on the heterojunction between porous silicon thin layer and crystalline silicon wafer depends on the concentration of ammonia in the measurement chamber. A porous silicon thin layer was formed by electrochemical etching on p-type silicon wafer. A gas and light transparent electrical contact was manufactured to this porous layer. Photo-EMF sensitivity corresponding to ammonia concentration in the range from 10 ppm to 1,000 ppm can be maximized by controlling the intensity of illumination light.

  19. Theoretical study of hole initiated impact ionization in bulk silicon and GaAs using a wave-vector-dependent numerical transition rate formulation within an ensemble Monte Carlo calculation

    NASA Technical Reports Server (NTRS)

    Oguzman, Ismail H.; Wang, Yang; Kolnik, Jan; Brennan, Kevin F.

    1995-01-01

    In this paper, calculations of the hole initiated interband impact ionization rate in bulk silicon and GaAs are presented based on an ensemble Monte Carlo simulation with the inclusion of a wave-vector-dependent numerical transition rate formulation. The ionization transition rate is determined for each of the three valence bands, heavy, light, and split-off, using Fermi's golden rule with a two-body, screened Coulomb interaction. The dielectric function used within the calculation is assumed to be wave-vector-dependent. Calculations of the field-dependent impact ionization rate as well as the quantum yield are presented. It is found from both the quantum yield results and examination of the hole distribution function that the effective threshold energy for hole initiated impact ionization is relatively soft, similar to that predicted for the corresponding electron initiated ionization events occur more frequently than either heavy or split-offf initiated ionization events in bulk silicon over the applied electric field strengths examined here, 250-500 kV/cm. Conversely,in GaAs, the vast majority of hole initated ionization events originate from holes within the split-off band.

  20. Silicon production process evaluations

    NASA Technical Reports Server (NTRS)

    1982-01-01

    Engineering design of the third distillation column in the process was accomplished. The initial design is based on a 94.35% recovery of dichlorosilane in the distillate and a 99.9% recovery of trichlorosilane in the bottoms. The specified separation is achieved at a reflux ratio of 15 with 20 trays (equilibrium stages). Additional specifications and results are reported including equipment size, temperatures and pressure. Specific raw material requirements necessary to produce the silicon in the process are presented. The primary raw materials include metallurgical grade silicon, silicon tetrachloride, hydrogen, copper (catalyst) and lime (waste treatment). Hydrogen chloride is produced as by product in the silicon deposition. Cost analysis of the process was initiated during this reporting period.

  1. Comparison of junctionless and inversion-mode p-type metal-oxide-semiconductor field-effect transistors in presence of hole-phonon interactions

    SciTech Connect

    Dib, E.; Carrillo-Nuñez, H.; Cavassilas, N.; Bescond, M.

    2016-01-28

    Junctionless transistors are being considered as one of the alternatives to conventional metal-oxide field-effect transistors. In this work, it is then presented a simulation study of silicon double-gated p-type junctionless transistors compared with its inversion-mode counterpart. The quantum transport problem is solved within the non-equilibrium Green's function formalism, whereas hole-phonon interactions are tackled by means of the self-consistent Born approximation. Our findings show that junctionless transistors should perform as good as a conventional transistor only for ultra-thin channels, with the disadvantage of requiring higher supply voltages in thicker channel configurations.

  2. 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.

  3. Spectral sensitivity of graphene/silicon heterojunction photodetectors

    NASA Astrophysics Data System (ADS)

    Riazimehr, Sarah; Bablich, Andreas; Schneider, Daniel; Kataria, Satender; Passi, Vikram; Yim, Chanyoung; Duesberg, Georg S.; Lemme, Max C.

    2016-01-01

    We have studied the optical properties of two-dimensional (2D) Schottky photodiode heterojunctions made of chemical vapor deposited (CVD) graphene on n- and p-type silicon (Si) substrates. Much better rectification behavior is observed from the diodes fabricated on n-Si substrates in comparison with the devices on p-Si substrates in dark condition. Also, graphene - n-Si photodiodes show a considerable responsivity of 270 mA W-1 within the silicon spectral range in DC reverse bias condition. The present results are furthermore compared with that of a molybdenum disulfide (MoS2) - p-type silicon photodiode.

  4. Origin of Photovoltage Enhancement via Interfacial Modification with Silver Nanoparticles Embedded in an a-SiC:H p-Type Layer in a-Si:H Solar Cells.

    PubMed

    Li, Tiantian; Zhang, Qixing; Ni, Jian; Huang, Qian; Zhang, Dekun; Li, Baozhang; Wei, Changchun; Yan, Baojie; Zhao, Ying; Zhang, Xiaodan

    2017-03-29

    We used silver nanoparticles (Ag-NPs) embedded in the p-type semiconductor layer of hydrogenated amorphous silicon (a-Si:H) solar cells in the Schottky barrier contact design to modify the interface between aluminum-doped ZnO (ZnO:Al, AZO) and p-type hydrogenated amorphous silicon carbide (p-a-SiC:H) without plasmonic absorption. The high work function of the Ag-NPs provided a good channel for the transport of photogenerated holes. A p-type nanocrystalline SiC:H layer was used to compensate for the real surface defects and voids on the surface of Ag-NPs to reduce recombination at the AZO/p-type layer interface, which then enhanced the photovoltage of single-junction a-Si:H solar cells to values as high as 1.01 V. The Ag-NPs were around 10 nm in diameter and thermally stable in the p-type a-SiC:H film at the solar-cell process temperature. We will also show that a wide range of photovoltages between 1.01 and 2.89 V could be obtained with single-, double-, and triple-junction solar cells based on the single-junction a-Si:H solar cells with tunable high photovoltage. These solar cells are suitable photocathodes for solar water-splitting applications.

  5. Opto-electrical properties of Sb-doped p-type ZnO nanowires

    SciTech Connect

    Kao, Tzu-Hsuan; Chen, Jui-Yuan; Chiu, Chung-Hua; Huang, Chun-Wei; Wu, Wen-Wei

    2014-03-17

    P-type ZnO nanowires (NWs) have attracted much attention in the past years due to the potential applications for optoelectronics and piezotronics. In this study, we have synthesized Sb-doped p-type ZnO NWs on Si (100) substrates by chemical vapor deposition with Aucatalyst. The Sb-doped ZnO NWs are single crystalline with high density, grown along [1-1-2] direction. The doping percentage of Sb is about 2.49%, which has been confirmed by X-ray photoelectron spectroscopy. The ZnO NW field effect transistor demonstrated its p-type characteristics. A high responsivity to ultraviolet photodetection was also observed. In addition, compared to intrinsic ZnO NWs, the conductivity of the Sb-doped ZnO NWs exhibited ∼2 orders of magnitude higher. These properties make the p-type ZnO NWs a promising candidate for electronic and optoelectronic devices.

  6. The Fabrication, Microstructural Characterization, and Internal Photoresponse of Platinum Silicide/P-Type Silicon and Iridium Silicide/P-Type Silicon Schottky Barrier Photodetectors for Infrared Focal Plane Arrays

    DTIC Science & Technology

    1991-10-01

    the spectral region of interest. This fact has motivated studies of both the fundamental limitations governing Schottky detector performance and the...to suffer from this problem. In addition to the sort of fundamental obstacle just discussed, IrSi arrays have been beset by other difficulties...distribution function. 5.6 Diffusion theory may be derived from fundamental transport theory under the assumption that the diffusing particles undergo

  7. Effect of p-type multi-walled carbon nanotubes for improving hydrogen storage behaviors

    SciTech Connect

    Lee, Seul-Yi; Yop Rhee, Kyong; Nahm, Seung-Hoon; Park, Soo-Jin

    2014-02-15

    In this study, the hydrogen storage behaviors of p-type multi-walled carbon nanotubes (MWNTs) were investigated through the surface modification of MWNTs by immersing them in sulfuric acid (H{sub 2}SO{sub 4}) and hydrogen peroxide (H{sub 2}O{sub 2}) at various ratios. The presence of acceptor-functional groups on the p-type MWNT surfaces was confirmed by X-ray photoelectron spectroscopy. Measurement of the zeta-potential determined the surface charge transfer and dispersion of the p-type MWMTs, and the hydrogen storage capacity was evaluated at 77 K and 1 bar. From the results obtained, it was found that acceptor-functional groups were introduced onto the MWNT surfaces, and the dispersion of MWNTs could be improved depending on the acid-mixed treatment conditions. The hydrogen storage was increased by acid-mixed treatments of up to 0.36 wt% in the p-type MWNTs, compared with 0.18 wt% in the As-received MWNTs. Consequently, the hydrogen storage capacities were greatly influenced by the acceptor-functional groups of p-type MWNT surfaces, resulting in increased electron acceptor–donor interaction at the interfaces. - Graphical abstract: Hydrogen storage behaviors of the p-type MWNTs with the acid-mixed treatments are described. Display Omitted Display Omitted.

  8. The Mobility, Resistivity and Carrier Density in p-Type Silicon Doped with Boron, Gallium and Indium.

    DTIC Science & Technology

    1979-08-01

    problem of the scattering of electrons by neutral hydogen atoms. The result is a temperature independent relaxation time given by 4; 37 Ti20tr 1N’ 1...collector diode. Mean values of resistivity, dopant density and Hall coefficient were determined by measuring five to eight selected test cells with a...a current regulated power supply (V-FR2503). The magnetic field strength was monitored by a Bell 620 gaussmeter with an STB4-0402 probe with a stated

  9. Process for making silicon

    NASA Technical Reports Server (NTRS)

    Levin, Harry (Inventor)

    1987-01-01

    A reactor apparatus (10) adapted for continuously producing molten, solar grade purity elemental silicon by thermal reaction of a suitable precursor gas, such as silane (SiH.sub.4), is disclosed. The reactor apparatus (10) includes an elongated reactor body (32) having graphite or carbon walls which are heated to a temperature exceeding the melting temperature of silicon. The precursor gas enters the reactor body (32) through an efficiently cooled inlet tube assembly (22) and a relatively thin carbon or graphite septum (44). The septum (44), being in contact on one side with the cooled inlet (22) and the heated interior of the reactor (32) on the other side, provides a sharp temperature gradient for the precursor gas entering the reactor (32) and renders the operation of the inlet tube assembly (22) substantially free of clogging. The precursor gas flows in the reactor (32) in a substantially smooth, substantially axial manner. Liquid silicon formed in the initial stages of the thermal reaction reacts with the graphite or carbon walls to provide a silicon carbide coating on the walls. The silicon carbide coated reactor is highly adapted for prolonged use for production of highly pure solar grade silicon. Liquid silicon (20) produced in the reactor apparatus (10) may be used directly in a Czochralski or other crystal shaping equipment.

  10. Genomic Comparison of P-Type ATPase Ion Pumps in Arabidopsis and Rice1

    PubMed Central

    Baxter, Ivan; Tchieu, Jason; Sussman, Michael R.; Boutry, Marc; Palmgren, Michael G.; Gribskov, Michael; Harper, Jeffrey F.; Axelsen, Kristian B.

    2003-01-01

    Members of the P-type ATPase ion pump superfamily are found in all three branches of life. Forty-six P-type ATPase genes were identified in Arabidopsis, the largest number yet identified in any organism. The recent completion of two draft sequences of the rice (Oryza sativa) genome allows for comparison of the full complement of P-type ATPases in two different plant species. Here, we identify a similar number (43) in rice, despite the rice genome being more than three times the size of Arabidopsis. The similarly large families suggest that both dicots and monocots have evolved with a large preexisting repertoire of P-type ATPases. Both Arabidopsis and rice have representative members in all five major subfamilies of P-type ATPases: heavy-metal ATPases (P1B), Ca2+-ATPases (endoplasmic reticulum-type Ca2+-ATPase and autoinhibited Ca2+-ATPase, P2A and P2B), H+-ATPases (autoinhibited H+-ATPase, P3A), putative aminophospholipid ATPases (ALA, P4), and a branch with unknown specificity (P5). The close pairing of similar isoforms in rice and Arabidopsis suggests potential orthologous relationships for all 43 rice P-type ATPases. A phylogenetic comparison of protein sequences and intron positions indicates that the common angiosperm ancestor had at least 23 P-type ATPases. Although little is known about unique and common features of related pumps, clear differences between some members of the calcium pumps indicate that evolutionarily conserved clusters may distinguish pumps with either different subcellular locations or biochemical functions. PMID:12805592

  11. Indentation plasticity and fracture in silicon

    NASA Technical Reports Server (NTRS)

    Rybicki, George C.; Pirouz, P.

    1988-01-01

    Measurements of the ductile-brittle transition temperature of heavily doped silicon were carried out using indentation techniques. Diamond pyramid hardness tests were performed on the (100) face of heavily doped N-type and P-type and intrinsic silicon single crystals. Tests were performed over the range 200 C to 850 C and loads of 100 to 500 g were used. Samples were subsequently etched to reveal dislocation rosettes produced by indentation. Intrinsic silicon underwent a ductile-brittle transition at 660 C, P-type at 645 C and N-type at 625 C. Hardness values varied from 1.1 GPa at 700 C to 11.7 GPa at 200 C. Significant effects of hardness on doping were present only at the highest temperatures. Lower loads generally produced higher hardness but load did not affect the Ductile-Brittle Transition Temperature (DBTT). Fracture toughness values ranged from 0.9 MPa m(1/2) at 200 C to 2.75 MPa m(1/2) near the DBTT. Doping did not affect the fracture toughness of silicon. P-type doping increased the size of dislocation rosettes observed after indentation, but N-type did not, in contradiction of the expected results. Results are discussed in terms of the effect of doping on the dislocation mobility in silicon.

  12. Fabrication and electrical characterization of Al/DNA-CTMA/ p-type a-Si:H photodiode based on DNA-CTMA biomaterial

    NASA Astrophysics Data System (ADS)

    Siva Pratap Reddy, M.; Puneetha, Peddathimula; Lee, Young-Woong; Jeong, Seong-Hoon; Park, Chinho

    2017-01-01

    In this work, a deoxyribonucleic acid-cetyltrimethylammonium chloride (DNA-CTMA) biomaterial based p-type hydrogenated amorphous silicon ( a-Si:H) photodiode (PD) is fabricated and its electrical characteristics are investigated. The Al/DNA-CTMA/ p-type a-Si:H PD parameters are studied using current-voltage ( I-V), capacitancevoltage-frequency ( C-V-f) and conductance-voltage-frequency ( G/ω-V-f) measurements. The barrier height and the ideality factor of the diode are found to be 0.78 eV and 1.9, respectively. The electrical and photoconductivity properties of the diode are analyzed by using dark I-V and transient photocurrent techniques. The C-V-f and G/ω-V-f measurements indicate that the capacitance and conductance of the diode depend on the voltage and frequency, respectively. The experimental results reveal that the decreases in capacitance and the increases in conductance with an increase in frequency can be explained on the basis of interface states ( N SS ). Series resistance ( R S ) measurements are performed on the diode and discussed here. The obtained electrical parameters confirm that the Al/DNA-CTMA/ p-type a-Si:H PD can be used as an optical sensor for the development of commercial applications that are environmentally benign. [Figure not available: see fulltext.

  13. Segmentation of the Outer Contact on P-Type Coaxial Germanium Detectors

    SciTech Connect

    Hull, Ethan L.; Pehl, Richard H.; Lathrop, James R.; Martin, Gregory N.; Mashburn, R. B.; Miley, Harry S.; Aalseth, Craig E.; Hossbach, Todd W.

    2006-09-21

    Germanium detector arrays are needed for low-level counting facilities. The practical applications of such user facilities include characterization of low-level radioactive samples. In addition, the same detector arrays can also perform important fundamental physics measurements including the search for rare events like neutrino-less double-beta decay. Coaxial germanium detectors having segmented outer contacts will provide the next level of sensitivity improvement in low background measurements. The segmented outer detector contact allows performance of advanced pulse shape analysis measurements that provide additional background reduction. Currently, n-type (reverse electrode) germanium coaxial detectors are used whenever a segmented coaxial detector is needed because the outer boron (electron barrier) contact is thin and can be segmented. Coaxial detectors fabricated from p-type germanium cost less, have better resolution, and are larger than n-type coaxial detectors. However, it is difficult to reliably segment p-type coaxial detectors because thick (~1 mm) lithium-diffused (hole barrier) contacts are the standard outside contact for p-type coaxial detectors. During this Phase 1 Small Business Innovation Research (SBIR) we have researched the possibility of using amorphous germanium contacts as a thin outer contact of p-type coaxial detectors that can be segmented. We have developed amorphous germanium contacts that provide a very high hole barrier on small planar detectors. These easily segmented amorphous germanium contacts have been demonstrated to withstand several thousand volts/cm electric fields with no measurable leakage current (<1 pA) from charge injection over the hole barrier. We have also demonstrated that the contact can be sputter deposited around and over the curved outside surface of a small p-type coaxial detector. The amorphous contact has shown good rectification properties on the outside of a small p-type coaxial detector. These encouraging

  14. Formation of p-type ZnO thin film through co-implantation

    NASA Astrophysics Data System (ADS)

    Chuang, Yao-Teng; Liou, Jhe-Wei; Woon, Wei-Yen

    2017-01-01

    We present a study on the formation of p-type ZnO thin film through ion implantation. Group V dopants (N, P) with different ionic radii are implanted into chemical vapor deposition grown ZnO thin film on GaN/sapphire substrates prior to thermal activation. It is found that mono-doped ZnO by N+ implantation results in n-type conductivity under thermal activation. Dual-doped ZnO film with a N:P ion implantation dose ratio of 4:1 is found to be p-type under certain thermal activation conditions. Higher p-type activation levels (1019 cm-3) under a wider thermal activation range are found for the N/P dual-doped ZnO film co-implanted by additional oxygen ions. From high resolution x-ray diffraction and x-ray photoelectron spectroscopy it is concluded that the observed p-type conductivities are a result of the promoted formation of PZn-4NO complex defects via the concurrent substitution of nitrogen at oxygen sites and phosphorus at zinc sites. The enhanced solubility and stability of acceptor defects in oxygen co-implanted dual-doped ZnO film are related to the reduction of oxygen vacancy defects at the surface. Our study demonstrates the prospect of the formation of stable p-type ZnO film through co-implantation.

  15. p-type Mesoscopic Nickel Oxide/Organometallic Perovskite Heterojunction Solar Cells

    PubMed Central

    Wang, Kuo-Chin; Jeng, Jun-Yuan; Shen, Po-Shen; Chang, Yu-Cheng; Diau, Eric Wei-Guang; Tsai, Cheng-Hung; Chao, Tzu-Yang; Hsu, Hsu-Cheng; Lin, Pei-Ying; Chen, Peter; Guo, Tzung-Fang; Wen, Ten-Chin

    2014-01-01

    In this article, we present a new paradigm for organometallic hybrid perovskite solar cell using NiO inorganic metal oxide nanocrystalline as p-type electrode material and realized the first mesoscopic NiO/perovskite/[6,6]-phenyl C61-butyric acid methyl ester (PC61BM) heterojunction photovoltaic device. The photo-induced transient absorption spectroscopy results verified that the architecture is an effective p-type sensitized junction, which is the first inorganic p-type, metal oxide contact material for perovskite-based solar cell. Power conversion efficiency of 9.51% was achieved under AM 1.5 G illumination, which significantly surpassed the reported conventional p-type dye-sensitized solar cells. The replacement of the organic hole transport materials by a p-type metal oxide has the advantages to provide robust device architecture for further development of all-inorganic perovskite-based thin-film solar cells and tandem photovoltaics. PMID:24755642

  16. Chemical-free n-type and p-type multilayer-graphene transistors

    NASA Astrophysics Data System (ADS)

    Dissanayake, D. M. N. M.; Eisaman, M. D.

    2016-08-01

    A single-step doping method to fabricate n- and p-type multilayer graphene (MG) top-gate field effect transistors (GFETs) is demonstrated. The transistors are fabricated on soda-lime glass substrates, with the n-type doping of MG caused by the sodium in the substrate without the addition of external chemicals. Placing a hydrogen silsesquioxane (HSQ) barrier layer between the MG and the substrate blocks the n-doping, resulting in p-type doping of the MG above regions patterned with HSQ. The HSQ is deposited in a single fabrication step using electron beam lithography, allowing the patterning of arbitrary sub-micron spatial patterns of n- and p-type doping. When a MG channel is deposited partially on the barrier and partially on the glass substrate, a p-type and n-type doping profile is created, which is used for fabricating complementary transistors pairs. Unlike chemically doped GFETs in which the external dopants are typically introduced from the top, these substrate doped GFETs allow for a top gate which gives a stronger electrostatic coupling to the channel, reducing the operating gate bias. Overall, this method enables scalable fabrication of n- and p-type complementary top-gated GFETs with high spatial resolution for graphene microelectronic applications.

  17. Native p-type transparent conductive CuI via intrinsic defects

    NASA Astrophysics Data System (ADS)

    Wang, Jing; Li, Jingbo; Li, Shu-Shen

    2011-09-01

    The ability of CuI to be doped p-type via the introduction of native defects has been investigated using first-principles pseudopotential calculations based on density functional theory. The Cu vacancy has a lower formation energy than any of the other native defects, which include I vacancy (VI), Cu interstitial (Cui), I interstitial (Ii), Cu antisite (CuI), and I antisite (ICu). Combined with its shallow acceptor level, it offers sufficient hole concentrations in CuI. The natural band alignments as compared to zinc-blende ZnS, ZnSe, and ZnTe have also been calculated in order to further identify the p-type dopability of CuI. It is found that CuI has a relatively high valence band maximum and conduction band minimum, which also makes it easy to dope CuI p-type in terms of the doping limit rule. In addition, the small effective mass of the light hole—about 0.303m0—can provide high mobility and p-type conductivity in CuI. All of these results make CuI an ideal candidate for native p-type materials

  18. Develop Silicone Encapsulation Systems for Terrestrial Silicon Solar Arrays

    NASA Technical Reports Server (NTRS)

    1979-01-01

    The results for Task 3 of the Low Cost Solar Array Project are presented. Task 3 is directed toward the development of a cost effective encapsulating system for photovoltaic modules using silicon based materials. The technical approach of the contract effort is divided into four special tasks: (1) technology review; (2) generation of concepts for screening and processing silicon encapsulation systems; (3) assessment of encapsulation concepts; and (4) evaluation of encapsulation concepts. The candidate silicon materials are reviewed. The silicon and modified silicon resins were chosen on the basis of similarity to materials with known weatherability, cost, initial tangential modulus, accelerated dirt pick-up test results and the ratio of the content of organic phenyl substitution of methyl substitution on the backbone of the silicon resin.

  19. Identification and design principles of low hole effective mass p-type transparent conducting oxides

    PubMed Central

    Hautier, Geoffroy; Miglio, Anna; Ceder, Gerbrand; Rignanese, Gian-Marco; Gonze, Xavier

    2013-01-01

    The development of high-performance transparent conducting oxides is critical to many technologies from transparent electronics to solar cells. Whereas n-type transparent conducting oxides are present in many devices, their p-type counterparts are not largely commercialized, as they exhibit much lower carrier mobilities due to the large hole effective masses of most oxides. Here we conduct a high-throughput computational search on thousands of binary and ternary oxides and identify several highly promising compounds displaying exceptionally low hole effective masses (up to an order of magnitude lower than state-of-the-art p-type transparent conducting oxides), as well as wide band gaps. In addition to the discovery of specific compounds, the chemical rationalization of our findings opens new directions, beyond current Cu-based chemistries, for the design and development of future p-type transparent conducting oxides. PMID:23939205

  20. DyP-type peroxidases comprise a novel heme peroxidase family.

    PubMed

    Sugano, Y

    2009-04-01

    Dye-decolorizing peroxidase (DyP) is produced by a basidiomycete (Thanatephorus cucumeris Dec 1) and is a member of a novel heme peroxidase family (DyP-type peroxidase family) that appears to be distinct from general peroxidases. Thus far, 80 putative members of this family have been registered in the PeroxiBase database (http://peroxibase.isbsib.ch/) and more than 400 homologous proteins have been detected via PSI-BLAST search. Although few studies have characterized the function and structure of these proteins, they appear to be bifunctional enzymes with hydrolase or oxygenase, as well as typical peroxidase activities. DyP-type peroxidase family suggests an ancient root compared with other general peroxidases because of their widespread distribution in the living world. In this review, firstly, an outline of the characteristics of DyP from T. cucumeris is presented and then interesting characteristics of the DyP-type peroxidase family are discussed.

  1. 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.

  2. 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.

  3. Defect Physics and Intrinsic p-TYPE Conductivity in Topological Insulator AuTlS2

    NASA Astrophysics Data System (ADS)

    Zhang, Jian-Min; Feng, Wangxiang; Yang, Pei; Shi, Lijie; Zhang, Ying

    2014-01-01

    Using first-principles calculations, we systematically investigate the defect physics in topological insulator AuTlS2. An optimal growth condition is explicitly proposed to guide for the experimental synthesis. The stabilities of various native point defects under different growth conditions and different carrier environments are studied in detail. We show that the p-type conductivity is strongly preferred in AuTlS2, and the band gap can be engineered by the control of intrinsic defects. Our results demonstrate that AuTlS2 is an ideal p-type topological insulator which can be easily integrated with traditional semiconductor.

  4. Carrier removal and defect behavior in p-type InP

    NASA Technical Reports Server (NTRS)

    Weinberg, I.; Swartz, C. K.; Drevinsky, P. J.

    1992-01-01

    A simple expression, obtained from the rate equation for defect production, was used to relate carrier removal to defect production and hole trapping rates in p-type InP after irradiation by 1-MeV electrons. Specific contributions to carrier removal from defect levels H3, H4, and H5 were determined from combined deep-level transient spectroscopy (DLTS) and measured carrier concentrations. An additional contribution was attributed to one or more defects not observed by the present DLTS measurements. The high trapping rate observed for H5 suggests that this defect, if present in relatively high concentration, could be dominant in p-type InP.

  5. Lithium-ion drifting: Application to the study of point defects in floating-zone silicon

    NASA Technical Reports Server (NTRS)

    Walton, J. T.; Wong, Y. K.; Zulehner, W.

    1997-01-01

    The use of lithium-ion (Li(+)) drifting to study the properties of point defects in p-type Floating-Zone (FZ) silicon crystals is reported. The Li(+) drift technique is used to detect the presence of vacancy-related defects (D defects) in certain p-type FZ silicon crystals. SUPREM-IV modeling suggests that the silicon point defect diffusivities are considerably higher than those commonly accepted, but are in reasonable agreement with values recently proposed. These results demonstrate the utility of Li(+) drifting in the study of silicon point defect properties in p-type FZ crystals. Finally, a straightforward measurement of the Li(+) compensation depth is shown to yield estimates of the vacancy-related defect concentration in p-type FZ crystals.

  6. 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.

  7. 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.

  8. Origin and evolution of metal P-type ATPases in Plantae (Archaeplastida)

    PubMed Central

    Hanikenne, Marc; Baurain, Denis

    2013-01-01

    Metal ATPases are a subfamily of P-type ATPases involved in the transport of metal cations across biological membranes. They all share an architecture featuring eight transmembrane domains in pairs of two and are found in prokaryotes as well as in a variety of Eukaryotes. In Arabidopsis thaliana, eight metal P-type ATPases have been described, four being specific to copper transport and four displaying a broader metal specificity, including zinc, cadmium, and possibly copper and calcium. So far, few efforts have been devoted to elucidating the origin and evolution of these proteins in Eukaryotes. In this work, we use large-scale phylogenetics to show that metal P-type ATPases form a homogenous group among P-type ATPases and that their specialization into either monovalent (Cu) or divalent (Zn, Cd…) metal transport stems from a gene duplication that took place early in the evolution of Life. Then, we demonstrate that the four subgroups of plant metal ATPases all have a different evolutionary origin and a specific taxonomic distribution, only one tracing back to the cyanobacterial progenitor of the chloroplast. Finally, we examine the subsequent evolution of these proteins in green plants and conclude that the genes thoroughly characterized in model organisms are often the result of lineage-specific gene duplications, which calls for caution when attempting to infer function from sequence similarity alone in non-model organisms. PMID:24575101

  9. A structural and functional perspective of DyP-type peroxidase family.

    PubMed

    Yoshida, Toru; Sugano, Yasushi

    2015-05-15

    Dye-decolorizing peroxidase from the basidiomycete Bjerkandera adusta Dec 1 (DyP) is a heme peroxidase. This name reflects its ability to degrade several anthraquinone dyes. The substrate specificity, the amino acid sequence, and the tertiary structure of DyP are different from those of the other heme peroxidase (super)families. Therefore, many proteins showing the similar amino acid sequences to that of DyP are called DyP-type peroxidase which is a new family of heme peroxidase identified in 2007. In fact, all structures of this family show a similar structure fold. However, this family includes many proteins whose amino acid sequence identity to DyP is lower than 15% and/or whose catalytic efficiency (kcat/Km) is a few orders of magnitude less than that of DyP. A protein showing an activity different from peroxidase activity (dechelatase activity) has been also reported. In addition, the precise physiological roles of DyP-type peroxidases are unknown. These facts raise a question of whether calling this family DyP-type peroxidase is suitable. Here, we review the differences and similarities of structure and function among this family and propose the reasonable new classification of DyP-type peroxidase family, that is, class P, I and V. In this contribution, we discuss the adequacy of this family name.

  10. Semiconductor liquid junction photocell having a p-type photoactive electrode

    SciTech Connect

    Heller, A.; Lewerenz, H.J.; Miller, B.

    1982-08-10

    A semiconductor liquid junction photocell has a photovoltaic junction between a p-type photoactive electrode comprising InP or Si and an electrolyte comprising a redox couple selected from the group consisting of V2+/V3+, Nb4+/Nb5+, and Ti3+/Ti4+ produces a stable photocurrent output.

  11. Silicon-Rich Silicon Carbide Hole-Selective Rear Contacts for Crystalline-Silicon-Based Solar Cells.

    PubMed

    Nogay, Gizem; Stuckelberger, Josua; Wyss, Philippe; Jeangros, Quentin; Allebé, Christophe; Niquille, Xavier; Debrot, Fabien; Despeisse, Matthieu; Haug, Franz-Josef; Löper, Philipp; Ballif, Christophe

    2016-12-28

    The use of passivating contacts compatible with typical homojunction thermal processes is one of the most promising approaches to realizing high-efficiency silicon solar cells. In this work, we investigate an alternative rear-passivating contact targeting facile implementation to industrial p-type solar cells. The contact structure consists of a chemically grown thin silicon oxide layer, which is capped with a boron-doped silicon-rich silicon carbide [SiCx(p)] layer and then annealed at 800-900 °C. Transmission electron microscopy reveals that the thin chemical oxide layer disappears upon thermal annealing up to 900 °C, leading to degraded surface passivation. We interpret this in terms of a chemical reaction between carbon atoms in the SiCx(p) layer and the adjacent chemical oxide layer. To prevent this reaction, an intrinsic silicon interlayer was introduced between the chemical oxide and the SiCx(p) layer. We show that this intrinsic silicon interlayer is beneficial for surface passivation. Optimized passivation is obtained with a 10-nm-thick intrinsic silicon interlayer, yielding an emitter saturation current density of 17 fA cm(-2) on p-type wafers, which translates into an implied open-circuit voltage of 708 mV. The potential of the developed contact at the rear side is further investigated by realizing a proof-of-concept hybrid solar cell, featuring a heterojunction front-side contact made of intrinsic amorphous silicon and phosphorus-doped amorphous silicon. Even though the presented cells are limited by front-side reflection and front-side parasitic absorption, the obtained cell with a Voc of 694.7 mV, a FF of 79.1%, and an efficiency of 20.44% demonstrates the potential of the p(+)/p-wafer full-side-passivated rear-side scheme shown here.

  12. Metal electrode integration on macroporous silicon: pore distribution and morphology

    PubMed Central

    2012-01-01

    In this work, a new approach for the one-step integration of interdigitated electrodes on macroporous silicon substrates is presented. Titanium/gold interdigitated electrodes are used to pattern p-type silicon substrates prior the anodization in an organic electrolyte. The electrolyte characteristics, conductivity, and pH have been found to affect the adherence of the metal layer on the silicon surface during the electrochemical etching. The impact of the metal pattern on size distribution and morphology of the resulting macroporous silicon layer is analyzed. A formation mechanism supported by finite element simulation is proposed. PMID:22799456

  13. Platinum monolayer electrocatalyst on gold nanostructures on silicon for photoelectrochemical hydrogen evolution.

    PubMed

    Kye, Joohong; Shin, Muncheol; Lim, Bora; Jang, Jae-Won; Oh, Ilwhan; Hwang, Seongpil

    2013-07-23

    Pt monolayer decorated gold nanostructured film on planar p-type silicon is utilized for photoelectrochemical H2 generation in this work. First, gold nanostructured film on silicon was spontaneously produced by galvanic displacement of the reduction of gold ion and the oxidation of silicon in the presence of fluoride anion. Second, underpotential deposition (UPD) of copper under illumination produced Cu monolayer on gold nanostructured film followed by galvanic exchange of less-noble Cu monolayer with more-noble PtCl6(2-). Pt(shell)/Au(core) on p-type silicon showed the similar activity with platinum nanoparticle on silicon for photoelectrochemical hydrogen evolution reaction in spite of low platinum loading. From Tafel analysis, Pt(shell)/Au(core) electrocatalyst shows the higher area-specific activity than platinum nanoparticle on silicon demonstrating the significant role of underlying gold for charge transfer reaction from silicon to H(+) through platinum catalyst.

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

    DOE PAGES

    Shi, Hongliang; Saparov, Bayrammurad; Singh, David J.; ...

    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

  15. Synthesis and characterization of silicon nanowire arrays for photovoltaic applications

    NASA Astrophysics Data System (ADS)

    Eichfeld, Sarah M.

    The overall objective of this thesis was the development of processes for the fabrication of radial p-n silicon nanowires (SiNWs) using bottom-up nanowire growth techniques on silicon and glass substrates. Vapor-liquid-solid (VLS) growth was carried out on Si(111) substrates using SiCl4 as the silicon precursor. Growth conditions including temperature, PSiCl4, PH2, and position were investigated to determine the optimum growth conditions for epitaxially oriented silicon nanowire arrays. The experiments revealed that the growth rate of the silicon nanowires exhibits a maximum as a function of PSiCl4 and P H2. Gas phase equilibrium calculations were used in conjunction with a mass transport model to explain the experimental data. The modeling results demonstrate a similar maximum in the mass of solid silicon predicted to form as a function of PSiCl4 and PH2, which results from a change in the gas phase concentration of SiHxCly and SiClx species. This results in a shift in the process from growth to etching with increasing PSiCl4. In general, for the atmospheric pressure conditions employed in this study, growth at higher temperatures >1000°C and higher SiCl4 concentrations gave the best results. The growth of silicon nanowire arrays on anodized alumina (AAO)-coated glass substrates was also investigated. Glass will not hold up to the high temperatures required for Si nanowire growth with SiCl4 so SiH 4 was used as the Si precursor instead. Initial studies were carried out to measure the resistivity of p-type and n-type silicon nanowires grown in freestanding AAO membranes. A series of nanowire samples were grown in which the doping and the nanowire length inside the membrane were varied. Circular metal contacts were deposited on the top surface of the membranes and the resistance of the nanowire arrays was measured. The measured resistance versus nanowire length was plotted and the nanowire resistivity was extracted from the slope. The resistivity of the silicon

  16. Friction and Wear Behavior of Silicon Under Conditions of Sliding.

    NASA Astrophysics Data System (ADS)

    Nadimpalli, Chandrasekhar Venkata

    Silicon is gaining importance as a material in micromechanical applications such as micromotors and microactuators. Friction and wear can affect the performance of these devices and hence it is important to study the friction and wear behavior of silicon. The deformation behavior of n-type silicon is fundamentally different from p-type. On deformation, n -type silicon may convert to p-type, but p-type silicon does not convert to n-type on deformation. This is related to the effect of dislocations interacting with the electrical charge carriers. Friction and wear behavior of n and p-type silicon was studied under conditions of sliding wear. Sliding was selected because the stress system associated with sliding introduces large plastic strains at the surface. The friction and wear behavior of n and p-type silicon is expected to be different due to the differences in their deformation behavior. Also, the n to p transition may show up in the friction and wear behavior. The samples were tested in air and in vacuum. Diamond was used as the slider. The wear tracks showed evidence of plastic flow. The morphology of this material was similar to that seen in more ductile materials. The coefficient of friction was also high. Other researchers have reported that DC Silicon transforms to a more ductile phase when sufficient pressure is applied. When shear stresses are present, as in sliding wear, the pressure for phase transformation has been reported to be about 8 GPa. The maximum pressure under the slider in the present set of experiments was estimated to be 8.2 GPa. Therefore, it is possible that transformed material extruded during sliding to produce the flow-like features observed at the wear track. The work involved in this phase transformation, as well as the work in deforming DC Silicon and/or the ductile product phase would contribute to the frictional energy. The debris from the air tests was DC silicon (as determined by XRD and TEM). No significant differences were

  17. Relativistic Doppler reflection as a probe for the initial relaxation of a non-equilibrium electron-hole plasma in silicon

    NASA Astrophysics Data System (ADS)

    Thomson, Mark D.; Meng, Fanqi; Sernelius, Bo E.; Roskos, Hartmut G.

    2015-10-01

    This paper reviews the status of investigations of the relativistic Doppler reflection of a broadband terahertz pulse at a counter-propagating plasma front of photo-excited charge carriers in undoped silicon. When a THz pulse with 20-THz bandwidth impinges onto a moving plasma front with a carrier density in the range of 1019 per cm3, one observes a spectral up-shift, which is, however, much less pronounced than expected from simulations assuming a Drude plasma characterized by a single carrier relaxation time τ of the order of 15-100 fs. Qualitative agreement between simulations and experiments can be achieved if τ is chosen to be less than 5 fs. In order to explore carrier relaxation in more detail, optical-pump/THz-probe experiments in the conventional co-propagation geometry were performed. If the pump-probe delay is long enough for monitoring of the equilibrium value of the scattering time, τ ranges from 200 fs at low carrier density to 20 fs in the 1019-cm-3 density range. For small (sub-picosecond) pump-probe delay, the data reveal a significantly faster scattering, which slows down during energy relaxation of the charge carriers.

  18. Thermal stability of boron nitride/silicon p-n heterojunction diodes

    SciTech Connect

    Teii, Kungen Mizusako, Yusei; Hori, Takuro; Matsumoto, Seiichiro

    2015-10-21

    Heterojunctions of p-type cubic boron nitride (cBN) and n-type silicon with sp{sup 2}-bonded BN (sp{sup 2}BN) interlayers are fabricated under low-energy ion impact by plasma-enhanced chemical vapor deposition, and their rectification properties are studied at temperatures up to 573 K. The rectification ratio is increased up to the order of 10{sup 5} at room temperature by optimizing the thickness of the sp{sup 2}BN interlayer and the cBN fraction for suppressing the reverse leakage current. A highly rectifying p-type cBN/thick sp{sup 2}BN/n-type silicon junction diode shows irreversible rectification properties mainly characterized by a marked decrease in reverse current by an order of magnitude in an initial temperature ramp/down cycle. This irreversible behavior is much more reduced by conducting the cycle twice or more. The temperature-dependent properties confirm an overall increase in effective barrier heights for carrier injection and conduction by biasing at high temperatures, which consequently increases the thermal stability of the diode performance.

  19. 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.

  20. The Form Effects of Magnetoresistivity in p-TYPE Diamond Films

    NASA Astrophysics Data System (ADS)

    Kong, Chun-Yang; Xu, Jie; Cui, Yu-Ting; Wang, Wan; Qing, Guo-Ping; Lan, Mao-Ping; Ruan, Hai-Bo

    The geometric form effects of magnetoresistivity (MR) from chemical vapor deposited p-type diamond films were investigated. The MR patterns (width/length ratio = 1, 2, 3, 4, 5, 6) were produced on p-type diamond films by photolithography and ion etching in oxygen plasma. The experimental results showed that the MR in diamond films with the strip structure changed with width-length ratio at magnetic field intensity of 3 T. The changes of MR strongly depended on the geometric form of the samples. With the width-length ratio increasing from 1 to 6, the MR increases from 0.08 to 1.0. It was almost changing linearly with the increase of width-to-length ratio. The geometric form effect is closely related to the Hall effect. A calculation formula of form effect of MR was presented.

  1. Measurement of the dead layer thickness in a p-type point contact germanium detector

    NASA Astrophysics Data System (ADS)

    Jiang, Hao; Yue, Qian; Li, Yu-Lan; Kang, Ke-Jun; Li, Yuan-Jing; Li, Jin; Lin, Shin-Ted; Liu, Shu-Kui; Ma, Hao; Ma, Jing-Lu; Su, Jian; Tsz-King Wong, Henry; Yang, Li-Tao; Zhao, Wei; Zeng, Zhi

    2016-09-01

    A 994 g mass p-type PCGe detector has been deployed during the first phase of the China Dark matter EXperiment, aiming at direct searches for light weakly interacting massive particles. Measuring the thickness of the dead layer of a p-type germanium detector is an issue of major importance since it determines the fiducial mass of the detector. This work reports a method using an uncollimated 133Ba source to determine the dead layer thickness. The experimental design, data analysis and Monte Carlo simulation processes, as well as the statistical and systematic uncertainties are described. A dead layer thickness of 1.02 mm was obtained based on a comparison between the experimental data and the simulated results. Supported by National Natural Science Foundation of China (10935005, 10945002, 11275107, 11175099)

  2. Ultra-thin ohmic contacts for p-type nitride light emitting devices

    DOEpatents

    Raffetto, Mark; Bharathan, Jayesh; Haberern, Kevin; Bergmann, Michael; Emerson, David; Ibbetson, James; Li, Ting

    2014-06-24

    A flip-chip semiconductor based Light Emitting Device (LED) can include an n-type semiconductor substrate and an n-type GaN epi-layer on the substrate. A p-type GaN epi-layer can be on the n-type GaN epi-layer and a metal ohmic contact p-electrode can be on the p-type GaN epi-layer, where the metal ohmic contact p-electrode can have an average thickness less than about 25 .ANG.. A reflector can be on the metal ohmic contact p-electrode and a metal stack can be on the reflector. An n-electrode can be on the substrate opposite the n-type GaN epi-layer and a bonding pad can be on the n-electrode.

  3. Temperature driven p-n-p type conduction switching materials: current trends and future directions.

    PubMed

    Guin, Satya N; Biswas, Kanishka

    2015-04-28

    Modern technological inventions have been going through a "renaissance" period. Development of new materials and understanding of fundamental structure-property correlations are the important steps to move further for advanced technologies. In modern technologies, inorganic semiconductors are the leading materials which are extensively used for different applications. In the current perspective, we present discussion on an important class of materials that show fascinating p-n-p type conduction switching, which can have potential applications in diodes or transistor devices that operate reversibly upon temperature or voltage change. We highlight the key concepts, present the current fundamental understanding and show the latest developments in the field of p-n-p type conduction switching. Finally, we point out the major challenges and opportunities in this field.

  4. p-type ZnS:N nanowires: Low-temperature solvothermal doping and optoelectronic properties

    SciTech Connect

    Wang, Ming-Zheng; Xie, Wei-Jie; Hu, Han; Yu, Yong-Qiang; Wu, Chun-Yan; Wang, Li; Luo, Lin-Bao

    2013-11-18

    Nitrogen doped p-type ZnS nanowires (NWs) were realized using thermal decomposition of triethylamine at a mild temperature. Field-effect transistors made from individual ZnS:N NWs revealed typical p-type conductivity behavior, with a hole mobility of 3.41 cm{sup 2}V{sup −1}s{sup −1} and a hole concentration of 1.67 × 10{sup 17} cm{sup −3}, respectively. Further analysis found that the ZnS:N NW is sensitive to UV light irradiation with high responsivity, photoconductive gain, and good spectral selectivity. The totality of this study suggests that the solvothermal doping method is highly feasible to dope one dimensional semiconductor nanostructures for optoelectronic devices application.

  5. CALCULATING THE HABITABLE ZONE OF BINARY STAR SYSTEMS. II. P-TYPE BINARIES

    SciTech Connect

    Haghighipour, Nader; Kaltenegger, Lisa

    2013-11-10

    We have developed a comprehensive methodology for calculating the circumbinary habitable zone (HZ) in planet-hosting P-type binary star systems. We present a general formalism for determining the contribution of each star of the binary to the total flux received at the top of the atmosphere of an Earth-like planet and use the Sun's HZ to calculate the inner and outer boundaries of the HZ around a binary star system. We apply our calculations to the Kepler's currently known circumbinary planetary systems and show the combined stellar flux that determines the boundaries of their HZs. We also show that the HZ in P-type systems is dynamic and, depending on the luminosity of the binary stars, their spectral types, and the binary eccentricity, its boundaries vary as the stars of the binary undergo their orbital motion. We present the details of our calculations and discuss the implications of the results.

  6. 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.

  7. P-type conductive amorphous oxides of transition metals from solution processing

    NASA Astrophysics Data System (ADS)

    Li, Jinwang; Kaneda, Toshihiko; Tokumitsu, Eisuke; Koyano, Mikio; Mitani, Tadaoki; Shimoda, Tatsuya

    2012-07-01

    We report a series of solution-processed p-type conductive amorphous Ln-M-O (a-Ln-M-O, where M = Ru, Ir, and Ln is a lanthanide element except Ce) having low resistivities (10-3 to 10-2 Ω cm). These oxides are thermally stable to a high degree, being amorphous up to 800 °C, and processable below 400 °C. Their film surfaces are smooth on the atomic scale, and the process allows patterning simply by direct imprinting without distortion of the pattern after annealing. These properties have high potential for use in printed electronics. The electron configurations of these oxides are apparently different from existing p-type oxides.

  8. Ferromagnetism in p-Type Manganese-Doped Zinc Oxide Quantum Dots.

    PubMed

    May, Joseph W; McMorris, Ryan J; Li, Xiaosong

    2012-05-17

    The magnetic exchange interactions between paramagnetic Mn(2+) dopants in the presence of a N(2-) p-type defect in zinc oxide quantum dots are studied using density functional theory. Spin-dependent delocalization of the N(2-) 2p acceptor level among the nearest-neighbor Mn(2+) dopants is observed. The calculations show that parallel Mn(2+) spin alignment is favored upon the formation of a nitrogen-bridged Mn-Mn dimer. Although the effect is short-ranged, the observed magnitude of stabilization of the ferromagnetic alignment of nearest-neighbor Mn(2+) spins arises from p-d exchange and suggests p-type Mn(2+)-doped ZnO quantum dots as excellent candidates for exhibiting room-temperature ferromagnetism. Analytical expressions are derived and supported by density functional theory calculations that show that the N(2-) concentration has a stronger influence on the magnetic splitting compared with that of the Mn(2+) concentration.

  9. Possible efficient p-type doping of AlN using Be: An ab initio study

    NASA Astrophysics Data System (ADS)

    Wu, R. Q.; Shen, L.; Yang, M.; Sha, Z. D.; Cai, Y. Q.; Feng, Y. P.; Huang, Z. G.; Wu, Q. Y.

    2007-10-01

    Spin density functional theory based ab initio study is carried out to investigate the feasibility of fabricating p-type AlN using Be as an efficient dopant. It is found that substitutional BeAl is an acceptor with an activation energy of 0.34eV. To overcome the low solubility of direct incorporation of Be into AlN and self-compensation from Be interstitials, we propose a hydrogen-assisted growth scheme which improves the solubility and suppresses interstitials. Oxygen is also found to be an effective codopant to activate Be in AlN. Our results suggest the possibility of improving p-type conductivity of AlN by Be doping.

  10. 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.

  11. Infrared absorption and visible transparency in heavily doped p-type BaSnO3

    NASA Astrophysics Data System (ADS)

    Li, Yuwei; Sun, Jifeng; Singh, David J.

    2017-01-01

    The recent experimental work shows that perovskite BaSnO3 can be heavily doped by K to become a stable p-type semiconductor. Here, we find that p-type perovskite BaSnO3 retains transparency for visible light while absorbing strongly in the infrared below 1.5 eV. The origin of the remarkable optical transparency even with heavy doping is that the interband transitions that are enabled by empty states at the top of the valence band are concentrated mainly in the energy range from 0.5 to 1.5 eV, i.e., not extending past the near IR. In contrast to n-type, the Burstein-Moss shift is slightly negative, but very small reflecting the heavier valence bands relative to the conduction bands.

  12. Method for producing high carrier concentration p-Type transparent conducting oxides

    DOEpatents

    Li, Xiaonan; Yan, Yanfa; Coutts, Timothy J.; Gessert, Timothy A.; Dehart, Clay M.

    2009-04-14

    A method for producing transparent p-type conducting oxide films without co-doping plasma enhancement or high temperature comprising: a) introducing a dialkyl metal at ambient temperature and a saturated pressure in a carrier gas into a low pressure deposition chamber, and b) introducing NO alone or with an oxidizer into the chamber under an environment sufficient to produce a metal-rich condition to enable NO decomposition and atomic nitrogen incorporation into the formed transparent metal conducting oxide.

  13. Investigation of negative photoconductivity in p-type Pb1-xSnxTe film

    NASA Astrophysics Data System (ADS)

    Tavares, M. A. B.; da Silva, M. J.; Peres, M. L.; de Castro, S.; Soares, D. A. W.; Okazaki, A. K.; Fornari, C. I.; Rappl, P. H. O.; Abramof, E.

    2017-01-01

    We investigated the negative photoconductivity (NPC) effect that was observed in a p-type Pb1-xSnxTe film for temperatures varying from 300 K down to 85 K. We found that this effect is a consequence of defect states located in the bandgap which act as trapping levels, changing the relation between generation and recombination rates. Theoretical calculations predict contributions to the NPC from both conduction and valence bands, which are in accordance with the experimental observations.

  14. 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.

  15. Guided Growth of Horizontal p-Type ZnTe Nanowires

    PubMed Central

    2016-01-01

    A major challenge toward large-scale integration of nanowires is the control over their alignment and position. A possible solution to this challenge is the guided growth process, which enables the synthesis of well-aligned horizontal nanowires that grow according to specific epitaxial or graphoepitaxial relations with the substrate. However, the guided growth of horizontal nanowires was demonstrated for a limited number of materials, most of which exhibit unintentional n-type behavior. Here we demonstrate the vapor–liquid–solid growth of guided horizontal ZnTe nanowires and nanowalls displaying p-type behavior on four different planes of sapphire. The growth directions of the nanowires are determined by epitaxial relations between the nanowires and the substrate or by a graphoepitaxial effect that guides their growth along nanogrooves or nanosteps along the surface. We characterized the crystallographic orientations and elemental composition of the nanowires using transmission electron microscopy and photoluminescence. The optoelectronic and electronic properties of the nanowires were studied by fabricating photodetectors and top-gate thin film transistors. These measurements showed that the guided ZnTe nanowires are p-type semiconductors and are photoconductive in the visible range. The guided growth of horizontal p-type nanowires opens up the possibility of parallel nanowire integration into functional systems with a variety of potential applications not available by other means. PMID:27885331

  16. Efficient synthesis of triarylamine-based dyes for p-type dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Wild, Martin; Griebel, Jan; Hajduk, Anna; Friedrich, Dirk; Stark, Annegret; Abel, Bernd; Siefermann, Katrin R.

    2016-05-01

    The class of triarylamine-based dyes has proven great potential as efficient light absorbers in inverse (p-type) dye sensitized solar cells (DSSCs). However, detailed investigation and further improvement of p-type DSSCs is strongly hindered by the fact that available synthesis routes of triarylamine-based dyes are inefficient and particularly demanding with regard to time and costs. Here, we report on an efficient synthesis strategy for triarylamine-based dyes for p-type DSSCs. A protocol for the synthesis of the dye-precursor (4-(bis(4-bromophenyl)amino)benzoic acid) is presented along with its X-ray crystal structure. The dye precursor is obtained from the commercially available 4(diphenylamino)benzaldehyde in a yield of 87% and serves as a starting point for the synthesis of various triarylamine-based dyes. Starting from the precursor we further describe a synthesis protocol for the dye 4-{bis[4‧-(2,2-dicyanovinyl)-[1,1‧-biphenyl]-4-yl]amino}benzoic acid (also known as dye P4) in a yield of 74%. All synthesis steps are characterized by high yields and high purities without the need for laborious purification steps and thus fulfill essential requirements for scale-up.

  17. Efficient synthesis of triarylamine-based dyes for p-type dye-sensitized solar cells

    PubMed Central

    Wild, Martin; Griebel, Jan; Hajduk, Anna; Friedrich, Dirk; Stark, Annegret; Abel, Bernd; Siefermann, Katrin R.

    2016-01-01

    The class of triarylamine-based dyes has proven great potential as efficient light absorbers in inverse (p-type) dye sensitized solar cells (DSSCs). However, detailed investigation and further improvement of p-type DSSCs is strongly hindered by the fact that available synthesis routes of triarylamine-based dyes are inefficient and particularly demanding with regard to time and costs. Here, we report on an efficient synthesis strategy for triarylamine-based dyes for p-type DSSCs. A protocol for the synthesis of the dye-precursor (4-(bis(4-bromophenyl)amino)benzoic acid) is presented along with its X-ray crystal structure. The dye precursor is obtained from the commercially available 4(diphenylamino)benzaldehyde in a yield of 87% and serves as a starting point for the synthesis of various triarylamine-based dyes. Starting from the precursor we further describe a synthesis protocol for the dye 4-{bis[4′-(2,2-dicyanovinyl)-[1,1′-biphenyl]-4-yl]amino}benzoic acid (also known as dye P4) in a yield of 74%. All synthesis steps are characterized by high yields and high purities without the need for laborious purification steps and thus fulfill essential requirements for scale-up. PMID:27196877

  18. Electronic inhomogeneity in n- and p-type PbTe detected by 125Te NMR

    NASA Astrophysics Data System (ADS)

    Levin, E. M.; Heremans, J. P.; Kanatzidis, M. G.; Schmidt-Rohr, K.

    2013-09-01

    125Te nuclear magnetic resonance spectra and spin-lattice relaxation of n- and p-type PbTe, self-doping narrow band-gap semiconductors, have been studied and compared to those of p-type GeTe. Spin-lattice relaxation in GeTe can be fit by one component, while that in both PbTe samples must be fit by at least two components, showing electronically homogeneous and inhomogeneous materials, respectively. For PbTe-based materials, the spin-lattice relaxation rate 1/T1 increases linearly with carrier concentration. The data for GeTe fall on the same line and allow us to extend this plot to higher concentrations. Long and short T1 components in both PbTe samples reflect “low,” ˜1017 cm-3, and “high,” ˜1018 cm-3, carrier concentration components. Carrier concentrations in both n- and p-type PbTe samples obtained from the Hall and Seebeck effects generally match the “high” carrier concentration component, and to some extent, ignore the “low” one. This demonstrates that the Hall and Seebeck effects may have a limited ability for the determination of carrier concentration in complex thermoelectric PbTe-based and other multicomponent materials.

  19. Doping CoSb3 p-type with Al substitution for Sb

    NASA Astrophysics Data System (ADS)

    Adams, Michael J.; Nielsen, Michele D.; Heremans, Joseph P.

    2014-03-01

    Skutterudites such as CoSb3 are compounds composed of group IX-B atoms (Co, Rh, and Ir) forming a simple cubic structure, and group V-A3 pnictide atoms (primarily Sb and As) forming rings inside 6 of every 8 cubes. The remaining cubes remain empty. A common method for reducing thermal conductivity is to introduce impurity atoms such as rare-earths in the cubes that act as rattlers. P-type doping of CoSb3 has led to some advances in zT, but the p-type material remains less performing than the n-type material due to the fact that the valence band, dominated by Sb levels, has a low effective mass. A promising method for improving p-type properties is to introduce an effective resonant level into the energy levels occupied by the light hole band, thereby increasing the Seebeck coefficient without strongly effecting other transport properties. A first attempt using Sn substitution was not successful. Here we try various concentrations of Al substituted at Sb sites to generate a resonant level. Material properties are measured and compared with a calculated Pisarenko relation, where thermopower is plotted as a function of hole concentration. Financial support for this investigation was provided by the U.S. Department of Energy (DOE)-U.S.-China Clean Energy Research Center (CERC-CVC) under the award No. DE-PI0000012.

  20. Effect of N2 flow during deposition on p-type ZnO film

    NASA Astrophysics Data System (ADS)

    Lin, Chiung-Wei; Liu, Bor-Chang

    2017-01-01

    In this study, the influence of a nitrogen source on p-type conductive ZnO films was studied. Rapid thermal oxidation was conducted to oxidize ZnN films and convert them to ZnO films. When an as-deposited ZnN film was prepared at a high nitrogen gas flow rate, the converted ZnO film possessed many acceptors and showed stable p-type conduction. This p-type conduction was attributed to the nitrogen gas flow providing many “No” states, which act as acceptors within the processed ZnO film. It was found that the as-deposited ZnN film prepared at a high nitrogen gas flow rate is oxidized slightly so that only a few nitrogen atoms were replaced by oxygen. The carrier concentration and mobility of the optimized oxidized ZnN film were 9.76 × 1017 cm-3 and 62.78 cm2 V-1 s-1, respectively. A good rectified current-voltage characteristic with a turn-on voltage of 3.65 V was achieved for the optimized ZnO:N/ZnO junction.

  1. 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

  2. Point contact silicon solar cells

    NASA Technical Reports Server (NTRS)

    Swanson, R. M.

    1986-01-01

    The construction of a 22.2% efficient single-crystal silicon solar cell fabricated at Stanford University is described. The cell dimensions were 3 x 5 mm and 100 microns thick with a base lifetime of 500 microseconds. The cell featured light trapping between a texturized top surface and a reflective bottom surface, small point contact diffusions, alternating between n-type and p-type in a polka-dot pattern on the bottom surface, and a surface passivation on all surfaces between contact regions.

  3. Characterization of near-infrared n-type {beta}-FeSi{sub 2}/p-type Si heterojunction photodiodes at room temperature

    SciTech Connect

    Shaban, Mahmoud; Nomoto, Keita; Izumi, Shota; Yoshitake, Tsuyoshi

    2009-06-01

    n-type {beta}-FeSi{sub 2}/p-type Si heterojunctions were fabricated from {beta}-FeSi{sub 2} films epitaxially grown on Si(111) by facing-target direct-current sputtering. Sharp film-substrate interfaces were confirmed by scanning electron microscopy. The current-voltage and photoresponse characteristics were measured at room temperature. They exhibited good rectifying properties and a change of approximately one order of magnitude in the current at a bias voltage of -1 V under illumination by a 6 mW, 1.31 {mu}m laser. The estimated detectivity was 1.5x10{sup 9} cm {radical}Hz W at 1.31 {mu}m. The results suggest that the {beta}-FeSi{sub 2}/Si heterojunctions can be used as near-infrared photodetectors that are compatible with silicon integrated circuits.

  4. Application of porous silicon in terahertz technology

    NASA Astrophysics Data System (ADS)

    Lo, Shu-Zee Alencious

    In this thesis, we discuss our efforts in developing porous silicon based devices for terahertz signal processing. In the first stage of our research, we demonstrate that porous silicon samples fabricated from highly doped p-type silicon can have adjustable refractive indices ranging from 1.5--2.1 and can exhibit a resistivity that is four orders of magnitude higher than that of the silicon wafer from which they were made. We show that the porous silicon becomes stable and relatively lossless after thermal oxidation. The partially oxidized porous silicon is shown to exhibit a smooth absorption spectrum, with low absorption loss of <10 cm-1 over the entire terahertz spectrum. As a proof of concept, we fabricated, for the first time, a porous silicon based multilayered Bragg filter with reflectance of 93% and full-width at half-maximum bandwidth of 0.26 THz. Compared with other multilayered filtering techniques, porous silicon has the advantage that it can be easily fabricated, and offers the possibility of forming multilayer and graded index structures for more advanced filters. The large surface area of nanoporous silicon makes it an especially attractive platform for applications in biochemical detection and diagnostics As part of our effort in developing terahertz waveguide for biosensing, we reported the world's first porous silicon based terahertz waveguide using the principle of surface plasmon polaritons. The effect of porous silicon film thickness on the propagation of surface plasmons is explained theoretically in this thesis and is found to be in good agreement with experimental results.

  5. Ferromagnetism in Silicon Single Crystals with Positively Charged Vacancy Clusters

    NASA Astrophysics Data System (ADS)

    Liu, Yu; Zhang, Xinghong; Yuan, Quan; Han, Jiecai; Zhou, Shengqiang; Song, Bo

    Defect-induced ferromagnetism provides an alternative for organic and semiconductor spintronics. Here, we investigated the magnetism in Silicon after neutron irradiation and try to correlate the observed magnetism to particular defects in Si. Commercially available p-type Si single crystal wafer is cut into pieces for performing neutron irradiations. The magnetic impurities are ruled out as they can not be detected by secondary ion mass spectroscopy. With positron annihilation lifetime spectroscopy, the positron trapping center corresponding to lifetime 375 ps is assigned to a kind of stable vacancy clusters of hexagonal rings (V6) and its concentration is enhanced by increasing neutron doses. After irradiation, the samples still show strong diamagnetism. The weak ferromagnetic signal in Si after irradiation enhances and then weakens with increasing irradiation doses. The saturation magnetization at room temperature is almost the same as that at 5 K. The X-ray magnetic circular dichroism further provides the direct evidence that Silicon is the origin of this ferromagnetism. Using first-principles calculations, it is found that positively charged V6 brings the spin polarization and the defects have coupling with each other. The work is financially supported by the Helmholtz Postdoc Programme (Initiative and Networking Fund, PD-146).

  6. Metallurgical Route to Produce Upgraded Silicon and Monosilane

    SciTech Connect

    Mukashev, B. N.; Abdullin, Kh A.; Tamendarov, M. F.; Turmagambetov, T. S.; Beketov, B. A.; Page, M. R.; Kline, D. M.

    2009-01-01

    We studied alumothermic reduction of silica from silicate slag to obtain silicon-containing Alloy-I and Alloy-II. Phosphorous industry waste and synthetic slag are used as a silicate slag that consists of more than 90% silicon and calcium oxides and less than l0% other elemental oxides. Silicon-containing Alloy-I was upgraded by acid leaching to silicon of a fine powder structure. Using this powder, we grew poly- and mono-crystalline p-type silicon, with resistivity of 0.24 {Omega} cm, by the Czochralski method. Silicon-containing Alloy-II was used for obtaining monosilane by aqueous treatment with hydrochloric acid under atmospheric conditions and without any catalyst. There was no trace of diborane, which is a common source for boron contamination in crude silane.

  7. In-Situ Characterization of Potential-Induced Degradation in Crystalline Silicon Photovoltaic Modules Through Dark I–V Measurements

    SciTech Connect

    Luo, Wei; Hacke, Peter; Singh, Jai Prakash; Chai, Jing; Wang, Yan; Ramakrishna, Seeram; Aberle, Armin G.; Khoo, Yong Sheng

    2017-01-01

    A temperature correction methodology for in-situ dark I-V(DIV) characterization of conventional p-type crystalline silicon photovoltaic (PV) modules undergoing potential-induced degradation (PID) is proposed.

  8. Surface property modification of silicon

    NASA Technical Reports Server (NTRS)

    Danyluk, S.

    1984-01-01

    The main emphasis of this work has been to determine the wear rate of silicon in fluid environments and the parameters that influence wear. Three tests were carried out on single crystal Czochralski silicon wafers: circular and linear multiple-scratch tests in fluids by a pyramidal diamond simulated fixed-particle abrasion; microhardness and three-point bend tests were used to determine the hardness and fracture toughness of abraded silicon and the extent of damage induced by abrasion. The wear rate of (100) and (111) n and p-type single crystal Cz silicon abraded by a pyramidal diamond in ethanol, methanol, acetone and de-ionized water was determined by measuring the cross-sectional areas of grooves of the circular and linear multiple-scratch tests. The wear rate depends on the loads on the diamond and is highest for ethanol and lowest for de-ionized water. The surface morphology of the grooves showed lateral and median cracks as well as a plastically deformed region. The hardness and fracture toughness are critical parameters that influence the wear rate. Microhardness tests were conducted to determine the hardness as influenced by fluids. Median cracks and the damage zone surrounding the indentations were also related to the fluid properties.

  9. Semiconducting p-type MgNiO:Li epitaxial films fabricated by cosputtering method

    SciTech Connect

    Kwon, Yong Hun; Chun, Sung Hyun; Cho, Hyung Koun

    2013-07-15

    Li-doped ternary Mg{sub x}Ni{sub 1-x}O thin films were deposited on (0001) Al{sub 2}O{sub 3} substrates by a radio frequency (RF) magnetron cosputtering method with MgO and NiO:Li targets. The Mg mole fraction and Li content were relatively controlled by changing RF power for the MgO target over a range of 0-300 W, while the NiO:Li target was kept at 150 W. As a result, all films were epitaxially grown on (0001) Al{sub 2}O{sub 3} substrates with the relationship of [110]{sub NiO}||[1110]{sub Al2O3}, [112]{sub NiO}||[2110]{sub Al2O3} (in-plane), and [111]{sub NiO}||[0001]{sub Al2O3} (out-of-plane), and showed p-type semiconducting properties. Furthermore, from x-ray diffraction patterns, the authors found that MgO was effectively mixed with NiO:Li without structural deformation due to low lattice mismatch (0.8%) between NiO and MgO. However, the excess Li contents degraded the crystallinity of the MgNiO films. The band-gap of films was continuously shifted from 3.66 eV (339 nm) to 4.15 eV (299 nm) by the RF power of the MgO target. A visible transmittance of more than 80% was exhibited at RF powers higher than 200 W. Ultimately, the electrical resistivity of p-type MgNiO films was improved from 7.5 to 673.5 {Omega}cm, indicating that the Li-doped MgNiO films are good candidates for transparent p-type semiconductors.

  10. Does p-type ohmic contact exist in WSe2-metal interfaces?

    NASA Astrophysics Data System (ADS)

    Wang, Yangyang; Yang, Ruo Xi; Quhe, Ruge; Zhong, Hongxia; Cong, Linxiao; Ye, Meng; Ni, Zeyuan; Song, Zhigang; Yang, Jinbo; Shi, Junjie; Li, Ju; Lu, Jing

    2015-12-01

    Formation of low-resistance metal contacts is the biggest challenge that masks the intrinsic exceptional electronic properties of two dimensional WSe2 devices. We present the first comparative study of the interfacial properties between monolayer/bilayer (ML/BL) WSe2 and Sc, Al, Ag, Au, Pd, and Pt contacts by using ab initio energy band calculations with inclusion of the spin-orbital coupling (SOC) effects and quantum transport simulations. The interlayer coupling tends to reduce both the electron and hole Schottky barrier heights (SBHs) and alters the polarity for the WSe2-Au contact, while the SOC chiefly reduces the hole SBH. In the absence of the SOC, the Pd contact has the smallest hole SBH. Dramatically, the Pt contact surpasses the Pd contact and becomes the p-type ohmic or quasi-ohmic contact with inclusion of the SOC. Therefore, p-type ohmic or quasi-ohmic contact exists in WSe2-metal interfaces. Our study provides a theoretical foundation for the selection of favorable metal electrodes in ML/BL WSe2 devices.Formation of low-resistance metal contacts is the biggest challenge that masks the intrinsic exceptional electronic properties of two dimensional WSe2 devices. We present the first comparative study of the interfacial properties between monolayer/bilayer (ML/BL) WSe2 and Sc, Al, Ag, Au, Pd, and Pt contacts by using ab initio energy band calculations with inclusion of the spin-orbital coupling (SOC) effects and quantum transport simulations. The interlayer coupling tends to reduce both the electron and hole Schottky barrier heights (SBHs) and alters the polarity for the WSe2-Au contact, while the SOC chiefly reduces the hole SBH. In the absence of the SOC, the Pd contact has the smallest hole SBH. Dramatically, the Pt contact surpasses the Pd contact and becomes the p-type ohmic or quasi-ohmic contact with inclusion of the SOC. Therefore, p-type ohmic or quasi-ohmic contact exists in WSe2-metal interfaces. Our study provides a theoretical foundation for

  11. Infrared analysis of hole properties of Mg-doped p-type InN films

    SciTech Connect

    Fujiwara, Masayuki; Ishitani, Yoshihiro; Wang Xinqiang; Che, Song-Bek; Yoshikawa, Akihiko

    2008-12-08

    Mg-doped InN films grown by plasma-assisted molecular beam epitaxy were characterized by infrared reflectance. Signatures of p-type conductivity in the spectra were obtained in the same doping density range where the existence of net acceptors was found by electrolyte capacitance-voltage measurements. Numerical spectrum analysis, which takes into account the large broadening factor of the normal mode energies of longitudinal optical phonon-plasmon coupling yielded high hole densities in the range of (0.1-1.2)x10{sup 19} cm{sup -3} and optical mobilities in the range of 25-70 cm{sup 2}/V s.

  12. 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.

  13. n/p-Type changeable semiconductor TiO2 prepared from NTA

    NASA Astrophysics Data System (ADS)

    Li, Qiuye; Wang, Xiaodong; Jin, Zhensheng; Yang, Dagang; Zhang, Shunli; Guo, Xinyong; Yang, Jianjun; Zhang, Zhijun

    2007-10-01

    A novel kind of nano-sized TiO2 (anatase) was obtained by high-temperature (400-700°C) dehydration of nanotube titanic acid (H2Ti2O4(OH)2, NTA). The high-temperature (400-700°C) dehydrated nanotube titanic acids (HD-NTAs) with a unique defect structure exhibited a p-type semiconductor behavior under visible-light irradiation (λ≥420 nm, E photon=2.95 eV), whereas exhibited an n-type semiconductor behavior irradiated with UV light (λ=365 nm, E photon=3.40 eV).

  14. Above bandgap luminescence of p-type GaAs epitaxial layers

    NASA Astrophysics Data System (ADS)

    Sapriel, J.; Chavignon, J.; Alexandre, F.; Azoulay, R.; Sermage, B.; Rao, K.; Voos, M.

    1991-08-01

    New photoluminescence bands are observed in p-type GaAs epitaxial layers at 300 and 80 K, above the bandgap. These bands are independent of the nature of the dopant (Zn, Be, C) and of the growth technique (MBE or MOCVD). Their intensities increase as a function of the p doping (1 × 10 17 < p < 2 × 10 20cm-3) and peak at energies which correspond to transitions between the Γ 6, L 6 and X 6 minima of the conduction band and the Γ 8 and Γ 7 maxima of the valence band.

  15. Silicon nitride/silicon carbide 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.

    1996-06-11

    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.

  16. Impact of the firing step on Al2O3 passivation on p-type Czochralski Si wafers: Electrical and chemical approaches

    NASA Astrophysics Data System (ADS)

    Pawlik, Matthieu; Vilcot, Jean-Pierre; Halbwax, Mathieu; Gauthier, Michel; Le Quang, Nam

    2015-08-01

    The development of an efficient surface passivation is a key feature of silicon solar cells towards the improvement of €/W ratio. An Al2O3 layer coated by plasma-enhanced atomic layer deposition has proven its efficiency to increase the minority carrier lifetime on p-type silicon. However, the firing step, which is a common part of the manufacturing process that includes metallic pastes for screen-printed contacts, ruins this passivation effect. On the basis of photoelectric, electric, and chemical experimental studies, a correlation is provided in this paper between the different microscopic and macroscopic behaviors that govern the passivation process. To show this correlation, photoconductance decay measurements have been carried out to determine minority carrier lifetime. Following which, the capacitance-voltage measurement results are used to extract electrical parameters, namely, the densities of interface defects and effective charges. In addition, complementing secondary ion mass spectrometry (SIMS) experiments revealed the different chemical species that can be relevant for the explanation of passivation quality and macroscopic electrical measurements.

  17. Photoconductivity of organic polymer films doped with porous silicon nanoparticles and ionic polymethine dyes

    SciTech Connect

    Davidenko, N. A. Skrichevsky, V. A.; Ishchenko, A. A.; Karlash, A. Yu.; Mokrinskaya, E. V.

    2009-05-15

    Features of electrical conductivity and photoconductivity of polyvinylbutyral films containing porous silicon nanoparticles and similar films doped with cationic and anionic polymethine dyes are studied. Sensitization of the photoelectric effect by dyes with different ionicities in films is explained by the possible photogeneration of holes and electrons from dye molecules and the intrinsic bipolar conductivity of porous silicon nanoparticles. It is assumed that the electronic conductivity in porous silicon nanoparticles is higher in comparison with p-type conductivity.

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

    DOEpatents

    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.

  19. p-Type Doping of GaN Nanowires Characterized by Photoelectrochemical Measurements.

    PubMed

    Kamimura, Jumpei; Bogdanoff, Peter; Ramsteiner, Manfred; Corfdir, Pierre; Feix, Felix; Geelhaar, Lutz; Riechert, Henning

    2017-03-08

    GaN nanowires (NWs) doped with Mg as a p-type impurity were grown on Si(111) substrates by plasma-assisted molecular beam epitaxy. In a systematic series of experiments, the amount of Mg supplied during NW growth was varied. The incorporation of Mg into the NWs was confirmed by the observation of donor-acceptor pairs and acceptor-bound excitons in low-temperature photoluminescence spectroscopy. Quantitative information about the Mg concentrations was deduced from Raman scattering by local vibrational modes related to Mg. In order to study the type and density of charge carriers present in the NWs, we employed two photoelectrochemical techniques, open-circuit potential and Mott-Schottky measurements. Both methods showed the expected transition from n-type to p-type conductivity with increasing Mg doping level, and the latter characterization technique allowed us to quantify the charge carrier concentration. Beyond the quantitative information obtained for Mg doping of GaN NWs, our systematic and comprehensive investigation demonstrates the benefit of photoelectrochemical methods for the analysis of doping in semiconductor NWs in general.

  20. Perovskite LaRhO3 as a p-type active layer in oxide photovoltaics

    NASA Astrophysics Data System (ADS)

    Nakamura, Masao; Krockenberger, Yoshiharu; Fujioka, Jun; Kawasaki, Masashi; Tokura, Yoshinori

    2015-02-01

    Perovskite-type transition-metal oxides have a wide variety of physical properties and triggered intensive research on functional devices in the form of heteroepitaxial junctions. However, there is a missing component that is a p-type conventional band semiconductor. LaRhO3 (LRO) is one of very few promising candidates having its bandgap between filled t2g and empty eg of Rh in low-spin state, but there has been no report on the synthesis of large-size single crystals or thin films. Here, we report on the junction properties of single-crystalline thin films of LRO grown on (110) oriented Nb-doped SrTiO3 substrates. The external quantum efficiency of the photo-electron conversion exceeds 1% in the visible-light region due to the wide depletion layer and long diffusion length of minority carriers in LRO. Clear indication of p-type band semiconducting character in a perovskite oxide of LRO will pave a way to explore oxide electronics of perovskite heterostructures.

  1. 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.

  2. Easily doped p-type, low hole effective mass, transparent oxides

    NASA Astrophysics Data System (ADS)

    Sarmadian, Nasrin; Saniz, Rolando; Partoens, Bart; Lamoen, Dirk

    2016-02-01

    Fulfillment of the promise of transparent electronics has been hindered until now largely by the lack of semiconductors that can be doped p-type in a stable way, and that at the same time present high hole mobility and are highly transparent in the visible spectrum. Here, a high-throughput study based on first-principles methods reveals four oxides, namely X2SeO2, with X = La, Pr, Nd, and Gd, which are unique in that they exhibit excellent characteristics for transparent electronic device applications – i.e., a direct band gap larger than 3.1 eV, an average hole effective mass below the electron rest mass, and good p-type dopability. Furthermore, for La2SeO2 it is explicitly shown that Na impurities substituting La are shallow acceptors in moderate to strong anion-rich growth conditions, with low formation energy, and that they will not be compensated by anion vacancies VO or VSe.

  3. Imperceptible and Ultraflexible p-Type Transistors and Macroelectronics Based on Carbon Nanotubes.

    PubMed

    Cao, Xuan; Cao, Yu; Zhou, Chongwu

    2016-01-26

    Flexible thin-film transistors based on semiconducting single-wall carbon nanotubes are promising for flexible digital circuits, artificial skins, radio frequency devices, active-matrix-based displays, and sensors due to the outstanding electrical properties and intrinsic mechanical strength of carbon nanotubes. Nevertheless, previous research effort only led to nanotube thin-film transistors with the smallest bending radius down to 1 mm. In this paper, we have realized the full potential of carbon nanotubes by making ultraflexible and imperceptible p-type transistors and circuits with a bending radius down to 40 μm. In addition, the resulted transistors show mobility up to 12.04 cm(2) V(-1) S(-1), high on-off ratio (∼10(6)), ultralight weight (<3 g/m(2)), and good mechanical robustness (accommodating severe crumpling and 67% compressive strain). Furthermore, the nanotube circuits can operate properly with 33% compressive strain. On the basis of the aforementioned features, our ultraflexible p-type nanotube transistors and circuits have great potential to work as indispensable components for ultraflexible complementary electronics.

  4. EEG/MEG forward simulation through h- and p-type finite elements

    NASA Astrophysics Data System (ADS)

    Pursiainen, S.

    2008-07-01

    Electro/Magnetoencephalography (EEG/MEG) is a non-invasive imaging modality, in which a primary current density generated by the neural activity in the brain is to be reconstructed from external electric potential/magnetic field measurements. This work focuses on effective and accurate simulation of the EEG/MEG forward model through the h- and p-versions of the finite element method (h- and p-FEM). The goal is to compare the effectiveness of these two versions in forward simulation. Both h- and p-type forward simulations are described and implemented, and the technical solutions found are discussed. These include, for example, suitable ways to generate a finite element mesh for a real head geometry through the use of different element types. Performances of the two implemented forward simulation types are compared by measuring directly the forward modeling error, as well as by computing reconstructions through a regularized FOCUSS (FOCal Underdetermined System Solver) algorithm. The results obtained suggest that the p-type performs better in terms of the forward modeling error. However, both types perform well in regularized FOCUSS reconstruction.

  5. Valence Band Structure of Highly Efficient p-type Thermoelectric PbTe-PbS Alloys

    SciTech Connect

    Jaworski, C. M.; Nielsen, Mechele; Wang, Hsin; Girard, Steven N.; Cai, Wei; Porter, Wallace D; Kanatzidis, Mercouri G.; Heremans, J. P.

    2013-01-01

    New experimental evidence is given relevant to the temperature-dependence of valence band structure of PbTe and PbTe1-xSx alloys (0.04 x 0.12), and its effect on the thermoelectric figure of merit zT. The x = 0.08 sample has zT ~ 1.55 at 773K. The magnetic field dependence of the high-temperature Hall resistivity of heavily p-type (> 1019 cm-3) Na-doped PbTe1-xSx reveals the presence of high-mobility electrons. This put in question prior analyses of the Hall coefficient and the conclusion that PbTe would be an indirect gap semiconductor at temperatures where its zT is optimal. Possible origins for these electrons are discussed: they can be induced by photoconductivity, or by the topology of the Fermi surface when the L and -bands merge. Negative values for the low-temperature thermopower are also observed. Our data show that PbTe continues to be a direct gap semiconductor at temperatures where the zT and S2 of p-type PbTe are optimal e.g. 700-900K. The previously suggested temperature induced rapid rise in energy of the heavy hole LVB relative to the light hole UVB is not supported by the experimental data.

  6. 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

  7. Inverse Design of p-Type Transparent Conducting Oxides for Energy Applications

    NASA Astrophysics Data System (ADS)

    Nagaraja, Arpun Ramaiah

    The Inverse Design approach to materials discovery was applied to developing materials that exhibit simultaneous p-type conductivity and optical transparency. Theoretical calculations predicted that Rh2ZnO4 and Cr2MnO4, well-known compounds with the spinel crystal structure, had the potential to be p-type transparent conducting oxides (p-TCOs). Bulk samples of these materials were synthesized, and their structural, optical, and electrical properties were characterized. Theory predicted that Rh2ZnO4 was largely a line compound, with slight deviations toward Zn-excess at higher temperatures. This off-stoichiometry was predicted to be the source of excess holes and thus p-type conductivity in Rh2ZnO4. Additionally, new methods in density functional theory predicted that hole conduction in Rh 2ZnO4 occurred via band transport, instead of small polaron hopping. In this work, experimental X-ray diffraction (XRD) studies confirmed that Rh2ZnO4 exhibits small off-stoichiometry toward Zn-rich compositions at 975°C. High temperature electrical measurements confirmed p-type conductivity, and room temperature Hall effect measurements yielded a hole mobility of 0.18 cm2/Vs for a bulk polycrystalline sample. In order to distinguish between band and polaron conduction, a revised analysis for high temperature electrical data was developed. This new analysis combines conductivity and thermopower data with theoretical calculations of the effective density of states in order to determine the behavior of the mobility with temperature. This method can be applied in the absence of a direct measurement of the temperature-dependence of the mobility. The results of this new method indicate that the behavior of Rh2ZnO4 is consistent with band conduction. Although intrinsic Cr2MnO4 is electrically insulating, lithium was predicted to be an effective p-type dopant, occupying the tetrahedral (Mn) site. Combined neutron/X-ray measurements of a doped specimen confirmed the predicted site

  8. Electrical characteristics of amorphous iron-tungsten contacts on silicon

    NASA Technical Reports Server (NTRS)

    Finetti, M.; Pan, E. T.-S.; Nicolet, M.-A.; Suni, I.

    1983-01-01

    The electrical characteristics of amorphous Fe-W contacts have been determined on both p-type and n-type silicon. The amorphous films were obtained by cosputtering from a composite target. Contact resistivities of 1 x 10 to the -7th and 2.8 x 10 to the -6th were measured on n(+) and p(+) silicon, respectively. These values remain constant after thermal treatment up to at least 500 C. A barrier height of 0.61 V was measured on n-type silicon.

  9. First principles molecular dynamics studies of elastic constants, ideal tensile strength, chemistry of crack initiation, and surface and cohesive energies in amorphous silicon

    NASA Astrophysics Data System (ADS)

    Shodja, Hossein M.; Tabatabaei, Maryam; Esfarjani, Keivan

    2014-09-01

    First principles Kohn-Sham density functional theory (DFT)-based molecular dynamics (MD) is employed to investigate some physical and mechanical properties of amorphous Si (a-Si) samples, as-quenched and annealed containing dangling and floating bonds as well as distorted tetrahedral bonds. The total energy and true stress as functions of the engineering strain for a-Si samples subjected to uniaxial tensile stress as well as uniaxial extension are obtained. It is well-known that the electron density of the state of matters can be determined via ab initio DFT-based MD with high accuracy. Using this technique, such inherent properties as the elastic constants, ideal tensile strength, ultimate tensile strength, and surface and cohesive energies will be calculated. Since the employed ab initio MD, in contrast to the empirical potentials simulations, is capable of providing the evolution of the electronic charge distribution, we can afford to study the chemistry of crack initiation and reconstructed surfaces at final rupture. The calculated cohesive and surface energies are compared with the available theoretical and experimental results; Tyson's empirical relation and universal binding energy relations (UBERs) are also examined. The calculated elastic constants using the symmetry-general scheme satisfy well the isotropic relation ?. To date, the ab initio MD samples of a-Si generated from the completely melted scheme were all free of three-fold-coordinated Si. In contrast, as we will show, by implementing special thermal treatments, generation of all inherent structural defects is possible. Based on the electronic charge distribution, dative bonds and trigonal prisms for, respectively, floating and dangling bonds have been observed.

  10. Surface photovoltage studies of p-type AlGaN layers after reactive-ion etching

    NASA Astrophysics Data System (ADS)

    McNamara, J. D.; Phumisithikul, K. L.; Baski, A. A.; Marini, J.; Shahedipour-Sandvik, F.; Das, S.; Reshchikov, M. A.

    2016-10-01

    The surface photovoltage (SPV) technique was used to study the surface and electrical properties of Mg-doped, p-type AlxGa1-xN (0.06 < x < 0.17) layers. SPV measurements reveal significant deviation from previous SPV studies on p-GaN:Mg thin films and from the predictions of a thermionic model for the SPV behavior. In particular, the SPV of the p-AlGaN:Mg layers exhibited slower-than-expected transients under ultraviolet illumination and delayed restoration to the initial dark value. The slow transients and delayed restorations can be attributed to a defective surface region which interferes with normal thermionic processes. The top 45 nm of the p-AlGaN:Mg layer was etched using a reactive-ion etch which caused the SPV behavior to be substantially different. From this study, it can be concluded that a defective, near-surface region is inhibiting the change in positive surface charge by allowing tunneling or hopping conductivity of holes from the bulk to the surface, or by the trapping of electrons traveling to the surface by a high concentration of defects in the near-surface region. Etching removes the defective layer and reveals a region of presumably higher quality, as evidenced by substantial changes in the SPV behavior.

  11. Persistent Hydrogen Production by the Photo-Assisted Microbial Electrolysis Cell Using a p-Type Polyaniline Nanofiber Cathode.

    PubMed

    Jeon, Yongwon; Kim, Sunghyun

    2016-12-08

    A microbial electrolysis cell, though considered as a promising, environmentally friendly technology for hydrogen production, suffers from concomitant production of methane. The high hydrogen/methane ratio at the initial operation stage decreases with time. Here we report for the first time the photoassisted microbial electrolysis cell (MEC) for persistent hydrogen production using polyaniline nanofibers as a cathode. Under 0.8 V external bias and laboratory fluorescent light illumination in a single-chamber MEC, continuous hydrogen production from acetate at a rate of 1.78 mH2 (3)  m(-3)  d(-1) with 79.2 % overall hydrogen recovery was achieved with negligible methane formation for six months. Energy efficiencies based on input electricity as well as input electricity plus substrate were 182 and 66.2 %, respectively. This was attributed to the p-type-semiconductor characteristics of polyaniline nanofibers in which photoexcited electrons are used to reduce protons at the surface and holes are reduced with electrons originating from acetate oxidation at the anode. This method can be extended to microbial wastewater treatment for hydrogen production.

  12. 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.

  13. Recombination activity of copper in silicon

    NASA Astrophysics Data System (ADS)

    Sachdeva, R.; Istratov, A. A.; Weber, E. R.

    2001-10-01

    The carrier recombination activity of copper in n-type and p-type silicon has been investigated. The minority carrier diffusion length has been found to decrease monotonically with increasing copper concentration in n Si and to exhibit a step-like behavior in p-type silicon at Cu concentrations above a certain critical level. It is suggested that the impact of copper on the minority carrier diffusion length is determined by the formation of copper precipitates. This process is retarded in perfect silicon due to the large lattice mismatch between Cu3Si and the silicon lattice and even more retarded in p Si, due to electrostatic repulsion effects between the positively charged copper precipitates and interstitial copper ions. Comparison of the impact of Cu on minority carrier diffusion length obtained with p-Si samples of different resistivity confirmed the electrostatic model. Studies of the impact of copper on minority carrier diffusion length in samples with internal gettering sites indicated that they provide heterogeneous nucleation sites for Cu precipitation at subcritical Cu concentration. Above a certain threshold of Cu concentration, the bulk recombination activity is dominated by quasihomogeneous formation of Cu precipitates, a process that is not detectably affected by the presence of oxide precipitates.

  14. Fitting Formulas For Determining The Existence Of S-Type And P-Type Habitable Zones In Binary Systems: First Results

    NASA Astrophysics Data System (ADS)

    Wang, Zhaopeng; Cuntz, Manfred

    2016-09-01

    We present initial work about attaining fitting formulas for the quick determination of the existence of S-type and P-type habitable zones in binary systems. Following previous work, we calculate the limits of the climatological habitable zone in binary systems (which sensitively depend on the system parameters) based on a joint constraint encompassing planetary orbital stability and a habitable region for a possible system planet. We also consider updated results on planetary climate models previously obtained by Kopparapu and collaborators. Fitting equations based on our work are presented for selected cases.

  15. Characterization of a P-type ATPase of the archaebacterium Methanococcus voltae.

    PubMed

    Dharmavaram, R M; Konisky, J

    1989-08-25

    The vanadate-sensitive ATPase of Methanococcus voltae has been purified by a procedure which includes, purification of the cytoplasmic membrane by sucrose gradient centrifugation, solubilization with Triton X-100, and DEAE-Sephadex and Sephacryl S-300 chromatography. While the DEAE-Sephadex step provided a preparation consisting of two polypeptides (74 and 52 kDa), the Sephacryl S-300 step yields a product with a subunit of 74 kDa. Incubation of either membranes or purified ATPase with [gamma-32P]ATP followed by acidic (pH 2.4) lithium dodecyl sulfate-polyacrylamide gel electrophoresis demonstrated the vanadate-sensitive labeling of a 74-kDa acyl phosphate intermediate. These results indicate that the M. voltae ATPase is of the P-type.

  16. P-type calcium channels are blocked by the alkaloid daurisoline.

    PubMed

    Lu, Y M; Fröstl, W; Dreessen, J; Knöpfel, T

    1994-07-21

    IN looking for a structurally defined non-peptide P-channel blocker we have tested the alkaloid daurisoline which has been isolated from traditional Chinese medicinal herb (Menispermum dauricum) used for the treatment of epilepsy, hypertension and asthma. We have found that daurisoline is an inhibitor of omega-Aga-IVA sensitive barium currents in cerebellar Purkinje cells and of excitatory postsynaptic potentials evoked in Purkinje cells by stimulating parallel fibres in acutely prepared cerebellar slices. Daurisoline did not significantly affect omega-Aga-IVA-insensitive barium currents recorded from granule cells freshly isolated from rat cerebellum. Daurisoline passes the blood-brain barrier and will, therefore, facilitate the functional characterization of brain calcium channels as well as the exploration of P-type calcium channels as possible drug targets.

  17. Photostable p-type dye-sensitized photoelectrochemical cells for water reduction.

    PubMed

    Ji, Zhiqiang; He, Mingfu; Huang, Zhongjie; Ozkan, Umit; Wu, Yiying

    2013-08-14

    A photostable p-type NiO photocathode based on a bifunctional cyclometalated ruthenium sensitizer and a cobaloxime catalyst has been created for visible-light-driven water reduction to produce H2. The sensitizer is anchored firmly on the surface of NiO, and the binding is resistant to the hydrolytic cleavage. The bifunctional sensitizer can also immobilize the water reduction catalyst. The resultant photoelectrode exhibits superior stability in aqueous solutions. Stable photocurrents have been observed over a period of hours. This finding is useful for addressing the degradation issue in dye-sensitized photoelectrochemical cells caused by desorption of dyes and catalysts. The high stability of our photocathodes should be important for the practical application of these devices for solar fuel production.

  18. Electron Traps Detected in p-type GaAsN Using Deep Level Transient Spectroscopy

    SciTech Connect

    Johnston, S.; Kurtz, S.; Friedman, D.; Ptak, A.; Ahrenkiel, R.; Crandall, R.

    2005-01-01

    The GaAsN alloy can have a band gap as small as 1.0 eV when the nitrogen composition is about 2%. Indium can also be added to the alloy to increase lattice matching to GaAs and Ge. These properties are advantageous for developing a highly-efficient, multi-junction solar cell. However, poor GaAsN cell properties, such as low open-circuit voltage, have led to inadequate performance. Deep-level transient spectroscopy of p-type GaAsN has identified an electron trap having an activation energy near 0.2 eV and a trap density of at least 1016 cm-3. This trap level appears with the addition of small amounts of nitrogen to GaAs, which also corresponds to an increased drop in open-circuit voltage.

  19. Chemical Composition of Nanoporous Layer Formed by Electrochemical Etching of p-Type GaAs.

    PubMed

    Bioud, Youcef A; Boucherif, Abderraouf; Belarouci, Ali; Paradis, Etienne; Drouin, Dominique; Arès, Richard

    2016-12-01

    We have performed a detailed characterization study of electrochemically etched p-type GaAs in a hydrofluoric acid-based electrolyte. The samples were investigated and characterized through cathodoluminescence (CL), X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDX), and X-ray photoelectron spectroscopy (XPS). It was found that after electrochemical etching, the porous layer showed a major decrease in the CL intensity and a change in chemical composition and in the crystalline phase. Contrary to previous reports on p-GaAs porosification, which stated that the formed layer is composed of porous GaAs, we report evidence that the porous layer is in fact mainly constituted of porous As2O3. Finally, a qualitative model is proposed to explain the porous As2O3 layer formation on p-GaAs substrate.

  20. Studies of minority carrier diffusion length increase in p-type ZnO:Sb

    SciTech Connect

    Lopatiuk-Tirpak, O.; Chernyak, L.; Xiu, F. X.; Liu, J. L.; Jang, S.; Ren, F.; Pearton, S. J.; Gartsman, K.; Feldman, Y.; Osinsky, A.; Chow, P.

    2006-10-15

    Minority electron diffusion length was measured in p-type, Sb-doped ZnO as a function of temperature using the electron beam induced current technique. A thermally induced increase of electron diffusion length was determined to have an activation energy of 184{+-}10 meV. Irradiation with a low energy (5 kV) electron beam also resulted in an increase of diffusion length with a similar activation energy (219{+-}8 meV). Both phenomena are suggested to involve a Sb{sub Zn}-2V{sub Zn} acceptor complex. Saturation and relaxation dynamics of minority carrier diffusion length are explored. Details of a possible mechanism for diffusion length increase are presented.

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

    SciTech Connect

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

    2009-10-01

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

  2. Highly conductive p-type amorphous oxides from low-temperature solution processing

    SciTech Connect

    Li Jinwang; Tokumitsu, Eisuke; Koyano, Mikio; Mitani, Tadaoki; Shimoda, Tatsuya

    2012-09-24

    We report solution-processed, highly conductive (resistivity 1.3-3.8 m{Omega} cm), p-type amorphous A-B-O (A = Bi, Pb; B = Ru, Ir), processable at temperatures (down to 240 Degree-Sign C) that are compatible with plastic substrates. The film surfaces are smooth on the atomic scale. Bi-Ru-O was analyzed in detail. A small optical bandgap (0.2 eV) with a valence band maximum (VBM) below but very close to the Fermi level (binding energy E{sub VBM} = 0.04 eV) explains the high conductivity and suggests that they are degenerated semiconductors. The conductivity changes from three-dimensional to two-dimensional with decreasing temperature across 25 K.

  3. p-Type zinc oxide films grown by infrared-light-assisted pulsed laser deposition

    NASA Astrophysics Data System (ADS)

    Hiraide, Toshihiro; Kurumi, Satoshi; Suzuki, Kaoru

    2013-03-01

    In this paper, ZnO films were grown on sapphire (0001) substrates by infrared-light-assisted pulsed-laser deposition (IRA-PLD). In addition, a nitrogen-plasma-assisted (PA-N) system was utilized for effectively doping the acceptor by radio frequency induction coupled plasma (RF-ICP). The effect of IRA-PLD and PA-N systems was investigated by studying the difference in substrate temperature with and without plasma assistance. We found that ZnO films exhibit no exciton emission with PA-N at a high temperature and that an increase in the substrate temperature yields ZnO films with a (002) and c-axis preferred orientation in a nitrogen (N2) gas atmosphere. ZnO films are changed from n-type to p-type at a substrate temperature of 673 K by IRA-PLD with an N2 background atmosphere.

  4. Inkjet printed circuits based on ambipolar and p-type carbon nanotube thin-film transistors.

    PubMed

    Kim, Bongjun; Geier, Michael L; Hersam, Mark C; Dodabalapur, Ananth

    2017-02-01

    Ambipolar and p-type single-walled carbon nanotube (SWCNT) thin-film transistors (TFTs) are reliably integrated into various complementary-like circuits on the same substrate by inkjet printing. We describe the fabrication and characteristics of inverters, ring oscillators, and NAND gates based on complementary-like circuits fabricated with such TFTs as building blocks. We also show that complementary-like circuits have potential use as chemical sensors in ambient conditions since changes to the TFT characteristics of the p-channel TFTs in the circuit alter the overall operating characteristics of the circuit. The use of circuits rather than individual devices as sensors integrates sensing and signal processing functions, thereby simplifying overall system design.

  5. Origin of resistivity anomaly in p-type leads chalcogenide multiphase compounds

    SciTech Connect

    Aminorroaya Yamini, Sima E-mail: jsnyder@caltech.edu; Dou, Shi Xue; Mitchell, David R. G.; Wang, Heng; Gibbs, Zachary M.; Pei, Yanzhong; Snyder, G. Jeffrey E-mail: jsnyder@caltech.edu

    2015-05-15

    The electrical resistivity curves for binary phase compounds of p-type lead chalcogenide (PbTe){sub (0.9−x)}(PbSe){sub 0.1}(PbS){sub x,} (x = 0.15, 0.2, 0.25), which contain PbS-rich secondary phases, show different behaviour on heating and cooling between 500-700 K. This is contrast to single phase compounds which exhibit similar behaviour on heating and cooling. We correlate these anomalies in the electrical resistivities of multiphase compounds to the variation in phase composition at high temperatures. The inhomogeneous distribution of dopants between the matrix and secondary phase is found to be crucial in the electronic transport properties of the multiphase compounds. These results can lead to further advances in designing composite Pb-chalcogenides with high thermoelectric performance.

  6. Inkjet printed circuits based on ambipolar and p-type carbon nanotube thin-film transistors

    PubMed Central

    Kim, Bongjun; Geier, Michael L.; Hersam, Mark C.; Dodabalapur, Ananth

    2017-01-01

    Ambipolar and p-type single-walled carbon nanotube (SWCNT) thin-film transistors (TFTs) are reliably integrated into various complementary-like circuits on the same substrate by inkjet printing. We describe the fabrication and characteristics of inverters, ring oscillators, and NAND gates based on complementary-like circuits fabricated with such TFTs as building blocks. We also show that complementary-like circuits have potential use as chemical sensors in ambient conditions since changes to the TFT characteristics of the p-channel TFTs in the circuit alter the overall operating characteristics of the circuit. The use of circuits rather than individual devices as sensors integrates sensing and signal processing functions, thereby simplifying overall system design. PMID:28145438

  7. Phonon bottleneck in p-type Ge/Si quantum dots

    SciTech Connect

    Yakimov, A. I.; Kirienko, V. V.; Armbrister, V. A.; Bloshkin, A. A.; Dvurechenskii, A. V.

    2015-11-23

    We study the effect of quantum dot size on the mid-infrared photo- and dark current, photoconductive gain, and hole capture probability in ten-period p-type Ge/Si quantum dot heterostructures. The dot dimensions are varied by changing the Ge coverage and the growth temperature during molecular beam epitaxy of Ge/Si(001) system in the Stranski-Krastanov growth mode. In all samples, we observed the general tendency: with decreasing the size of the dots, the dark current and hole capture probability are reduced, while the photoconductive gain and photoresponse are enhanced. Suppression of the hole capture probability in small-sized quantum dots is attributed to a quenched electron-phonon scattering due to phonon bottleneck.

  8. Inkjet printed circuits based on ambipolar and p-type carbon nanotube thin-film transistors

    NASA Astrophysics Data System (ADS)

    Kim, Bongjun; Geier, Michael L.; Hersam, Mark C.; Dodabalapur, Ananth

    2017-02-01

    Ambipolar and p-type single-walled carbon nanotube (SWCNT) thin-film transistors (TFTs) are reliably integrated into various complementary-like circuits on the same substrate by inkjet printing. We describe the fabrication and characteristics of inverters, ring oscillators, and NAND gates based on complementary-like circuits fabricated with such TFTs as building blocks. We also show that complementary-like circuits have potential use as chemical sensors in ambient conditions since changes to the TFT characteristics of the p-channel TFTs in the circuit alter the overall operating characteristics of the circuit. The use of circuits rather than individual devices as sensors integrates sensing and signal processing functions, thereby simplifying overall system design.

  9. Electronic characteristics of p-type transparent SnO monolayer with high carrier mobility

    NASA Astrophysics Data System (ADS)

    Du, Juan; Xia, Congxin; Liu, Yaming; Li, Xueping; Peng, Yuting; Wei, Shuyi

    2017-04-01

    More recently, two-dimensional (2D) SnO nanosheets are attaching great attention due to its excellent carrier mobility and transparent characteristics. Here, the stability, electronic structures and carrier mobility of SnO monolayer are investigated by using first-principles calculations. The calculations of the phonon dispersion spectra indicate that SnO monolayer is dynamically stable. Moreover, the band gap values are decreased from 3.93 eV to 2.75 eV when the tensile strain is applied from 0% to 12%. Interestingly, SnO monolayer is a p-type transparent semiconducting oxide with hole mobility of 641 cm2 V-1 s-1, which is much higher than that of MoS2 monolayer. These findings make SnO monolayer becomes a promising 2D material for applications in nanoelectronic devices.

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

    NASA Astrophysics Data System (ADS)

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

    2009-10-01

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

  11. Conduction type control from n to p type for organic pigment films purified by reactive sublimation

    NASA Astrophysics Data System (ADS)

    Hiramoto, Masahiro; Ihara, Kiyoaki; Fukusumi, Hiroyuki; Yokoyama, Masaaki

    1995-12-01

    The effects of purification by reactive sublimation technique and bromine doping on the Fermi level and the photovoltaic properties of n-type perylene pigment films were investigated. Photovoltage arisen from the Schottky junction between n-type perylene pigment film and Au increased significantly by repeating the train sublimation under methylamine gas atmosphere. This phenomenon was revealed to be due to the negative shift of the Fermi level resulting from the effective removal of unknown but specific impurity acting as an acceptor by reactive sublimation. On the other hand, by bromine doping, Fermi level of the pigment film shifted largely to a positive direction and reached the nearby valence band, while the direction of photocurrent flow arising from the Schottky junction with Au was reversed. This result is a clear demonstration of alternating the type of conduction from n type to p type. This means that the pn control of organic semiconductors is possible.

  12. Polymer photovoltaic cell embedded with p-type single walled carbon nanotubes fabricated by spray process.

    PubMed

    Kim, Dal-Ho; Park, Jea-Gun

    2012-08-17

    In the current study, we fabricated polymer (poly(3-hexylthiophene-2,5-diyl) (P3HT) and [6,6]-phenyl-C(61) butyric-acid methyl-ester (PCBM) blend) photovoltaic (PV) cells embedded with p-type single walled carbon nanotubes (SWCNTs) with tangled hair morphology. The power conversion efficiency (PCE) rapidly increased with SWCNT concentration of up to 6.83% coverage, and then decreased and saturated with increasing SWCNT concentration; i.e., the PCE peaks at 5.379%. This tendency is mainly associated with hole transport efficiency toward the transparent electrode (indium-tin-oxide (ITO)) via SWCNTs, directly determining the series resistance and shunt resistance of the polymer PV cells embedded with SWCNTs: the PV cell is increasing shunt resistance and decreasing series resistance.

  13. Enhancement of p-type conductivity in nanocrystalline BaTiO3 ceramics

    NASA Astrophysics Data System (ADS)

    Guo, Xin; Pithan, Christian; Ohly, Christian; Jia, Chun-Lin; Dornseiffer, Jügen; Haegel, Franz-Hubert; Waser, Rainer

    2005-02-01

    Undoped BaTiO3 ceramic samples with an average grain size of ˜35nm were prepared and the electrical properties investigated. The defect structure is dominated by acceptor impurities; therefore, the conductivity of nanocrystalline BaTiO3 is of p-type. Comparing with microcrystalline BaTiO3, the conductivity of nanocrystalline BaTiO3 is about 1 to 2 orders of magnitude higher and the activation energy remarkably lower, which is ascribed to a greatly reduced oxidation enthalpy in nanocrystalline BaTiO3 (˜0.3 versus ˜0.92eV for microcrystalline BaTiO3).

  14. Formation and annealing of radiation defects in tin-doped p-type germanium crystals

    SciTech Connect

    Litvinov, V. V. Petukh, A. N.; Pokotilo, Ju. M.; Markevich, V. P.; Lastovskii, S. B.

    2012-05-15

    The effect of tin on the formation and annealing of radiation defects in p-type germanium crystals irradiated with 6-MeV electrons at a temperature of 80 K is studied. It is shown that acceptor complexes SnV with a hole ionization enthalpy of 0.16 eV are dominant in irradiated Ge:(Sn, Ga) crystals after their heating to a temperature of 300 K. These complexes disappeared as a result of the annealing of irradiated crystals in the temperature range 30-75 Degree-Sign C. Annealing of irradiated crystals at temperatures in the range 110-150 Degree-Sign C brings about the formation of deep-level centers with a donor level at E{sub v} + 0.29 eV; this center is presumably related to a complex consisting of a tin atom and an interstitial gallium atom.

  15. Chemical synthesis of p-type nanocrystalline copper selenide thin films for heterojunction solar cells

    NASA Astrophysics Data System (ADS)

    Ambade, Swapnil B.; Mane, R. S.; Kale, S. S.; Sonawane, S. H.; Shaikh, Arif V.; Han, Sung-Hwan

    2006-12-01

    Nanocrystalline thin films of copper selenide have been grown on glass and tin doped-indium oxide substrates using chemical method. At ambient temperature, golden films have been synthesized and annealed at 200 °C for 1 h and were examined for their structural, surface morphological and optical properties by means of X-ray diffraction (XRD), scanning electron microscopy and UV-vis spectrophotometry techniques, respectively. Cu 2- xSe phase was confirmed by XRD pattern and spherical grains of 30 ± 4 - 40 ± 4 nm in size aggregated over about 130 ± 10 nm islands were seen by SEM images. Effect of annealing on crystallinity improvement, band edge shift and photoelectrochemical performance (under 80 mW/cm 2 light intensity and in lithium iodide electrolyte) has been studied and reported. Observed p-type electrical conductivity in copper selenide thin films make it a suitable candidate for heterojunction solar cells.

  16. Improved performance of P-type DSCs with a compact blocking layer coated by different thicknesses

    NASA Astrophysics Data System (ADS)

    Ho, Phuong; Bao, Le Quoc; Cheruku, Rajesh; Kim, Jae Hong

    2016-09-01

    The introduction of different thicknesses of a compact NiO blocking layer coating with different spin speeds on FTO and followed by a coating of photoactive NiO electrode for p-type dye-sensitized solar cells ( p-DSCs). This study examined the fabrication of a compact NiO blocking layer by decomposing an ethanolic precursor solution of nickel acetate tetrahydrate. The DCBZ dye used as the photosensitizer for the NiO electrode in the p-DSCs device and their performances have been analyzed. The enhancement of photovoltaic performance and resulted from an increase in the power conversion efficiency ( η). The electrochemical impedance spectroscopy (EIS) measurement demonstrated that charge recombination was suppressed when a compact NiO blocking layer was applied. The results showed that the best p-DSC was achieved by employing 3000 rpm spin-coated process for different times of blocking layer.

  17. Rat submaxillary gland contains predominantly P-type tachykinin binding sites

    SciTech Connect

    Buck, S.H.; Burcher, E.

    1985-11-01

    The specific binding of the /sup 125/I-Bolton-Hunter labeled tachykinins substance K (BHSK), eledoisin (BHE), and substance P (BHSP) was examined in crude membrane suspensions and by autoradiography in rat submaxillary gland. All three ligands at 0.1 nM concentrations exhibited binding that was inhibited by tachykinins in a potency rank order of substance P greater than physalaemin greater than substance K greater than eledoisin greater than kassinin greater than neuromedin K with slope factors essentially equal to unity. All tachykinins were 5 to 10 times more potent in inhibiting BHSK and BHE binding compared to BHSP binding. Autoradiographic visualization of BHSK and BHSP binding sites in the gland revealed extensive labeling of mucous and serous acini. The intensity of labeling was much less for BHSK than for BHSP. The results indicate that the rat submaxillary gland contains predominantly P-type tachykinin binding sites.

  18. Method for enhancing the solubility of dopants in silicon

    DOEpatents

    Sadigh, Babak; Lenosky, Thomas J.; De La Rubia, Tomas Diaz

    2003-09-30

    A method for enhancing the equilibrium solid solubility of dopants in silicon, germanium and silicon-germanium alloys. The method involves subjecting silicon-based substrate to biaxial or compression strain. It has been determined that boron solubility was largely enhanced (more than 100%) by a compressive bi-axial strain, based on a size-mismatch theory since the boron atoms are smaller than the silicon atoms. It has been found that the large enhancement or mixing properties of dopants in silicon and germanium substrates is primarily governed by their, and to second order by their size-mismatch with the substrate. Further, it has been determined that the dopant solubility enhancement with strain is most effective when the charge and the size-mismatch of the impurity favor the same type of strain. Thus, the solid solubility of small p-type (e.g., boron) as well as large n-type (e.g., arsenic) dopants can be raised most dramatically by appropriate bi-axial (compressive) strain, and that solubility of a large p-type dopant (e.g, indium) in silicon will be raised due to size-mismatch with silicon, which favors tensile strain, while its negative charge prefers compressive strain, and thus the two effects counteract each other.

  19. Gate tunable graphene-silicon Ohmic/Schottky contacts

    NASA Astrophysics Data System (ADS)

    Chen, Chun-Chung; Chang, Chia-Chi; Li, Zhen; Levi, A. F. J.; Cronin, Stephen B.

    2012-11-01

    We show that the I-V characteristics of graphene-silicon junctions can be actively tuned from rectifying to Ohmic behavior by electrostatically doping the graphene with a polymer electrolyte gate. Under zero applied gate voltage, we observe rectifying I-V characteristics, demonstrating the formation of a Schottky junction at the graphene-silicon interface. Through appropriate gating, the Fermi energy of the graphene can be varied to match the conduction or valence band of silicon, thus forming Ohmic contacts with both n- and p-type silicon. Over the applied gate voltage range, the low bias conductance can be varied by more than three orders of magnitude. By varying the top gate voltage from -4 to +4 V, the Fermi energy of the graphene is shifted between -3.78 and -5.47 eV; a shift of ±0.85 eV from the charge neutrality point. Since the conduction and valence bands of the underlying silicon substrate lie within this range, at -4.01 and -5.13 eV, the Schottky barrier height and depletion width can be decreased to zero for both n- and p-type silicon under the appropriate top gating conditions. I-V characteristics taken under illumination show that the photo-induced current can be increased or decreased based on the graphene-silicon work function difference.

  20. 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.

  1. Inherent formation of porous p-type Si nanowires using palladium-assisted chemical etching

    NASA Astrophysics Data System (ADS)

    Chen, Jun-Ming; Chen, Chia-Yuan; Wong, C. P.; Chen, Chia-Yun

    2017-01-01

    Porous silicon (Si) nanowire arrays were directly fabricated from lightly p-doped Si substrates using a palladium (Pd)-assisted chemical etching at room temperature. The mechanistic studies indicated that anodic dissolution of Si was established by the accumulated positive charges at Pd/Si schottky interfaces in the presence of H2O2 oxidants. In addition to the primary etching direction vertically to the substrate planes, the additional sidewall etching was stimulated by the separated Pd nanoparticles during reaction that constitutes the porous features covering on the nanowires surfaces thoroughly. These combined effects lead to the distinct etching characteristics and remarkable photoluminescent properties of resulted nanostructures.

  2. Glucose-assisted reduction achieved transparent p-type cuprous oxide thin film by a solution method

    NASA Astrophysics Data System (ADS)

    Nie, Sha; Sun, Jian; Gong, Hao; Chen, Zequn; Huang, Yifei; Xu, Jianmei; Zhao, Ling; Zhou, Wei; Wang, Qing

    2016-08-01

    The fabrication of p-type cuprous oxide thin film via a cheap and simple chemical method has been known as challenging. We first find that glucose can assist reduce Cu to a lower valence state in the preparation of cuprous oxide films by the sol-gel method. By first adding glucose in the sol as reducing agent, oxidation from the oxygen in the environment is limited and transparent p-type cuprous oxide films are eventually achieved under optimized experimental conditions. We have developed a p-type cuprous oxide thin film with an optimal Hall mobility of ∼8 cm2/Vs and an optical transmittance of 78%.

  3. First-principles study of Be doped CuAlS2 for p-type transparent conductive materials

    NASA Astrophysics Data System (ADS)

    Huang, Dan; Zhao, Yu-Jun; Tian, Ren-Yu; Chen, Di-Hu; Nie, Jian-Jun; Cai, Xin-Hua; Yao, Chun-Mei

    2011-06-01

    CuAlS2 has attracted much attention recently as a p-type transparent conductive material. In this paper, we investigate the site preference of substitutional Be in CuAlS2 and the transition level of BeAl using the first-principles calculation. We find that Be would be doped effectively at Al sites in CuAlS2 as a good p-type dopant. In addition, we speculate that Be-Mg or Be-Zn codoped CuAlS2 could have a mobility enhancement and thus a good p-type conductivity due to low lattice distortion.

  4. The Establishment of a Production-ready Manufacturing Process Utilizing Thin Silicon Substrates for Solar Cells

    NASA Technical Reports Server (NTRS)

    Pryor, R. A.

    1979-01-01

    During the months of February and March, work towards the goals of the contract were started as scheduled. The first shipment of thin substrates were received and wafer processing was initiated. The objective of the contract is to investigate, develop and characterize the methods for establishing a production-ready manufacturing process which utilizes thin silicon substrates for solar cells. The thin substrates to be manufactured are three inches diameter, p-type Czochralski wafers of approximately 1 Omega cm resistivity. The wafers are prepared by sawing directly to thickness of 8 mils and 5 mils. To ensure removal of residual saw damage, most substrates are chemically etched to final thicknesses of 7 mils and 4 mils. The thin substrates are used to fabricate solar cells by standard processing techniques.

  5. Intravitreal properties of porous silicon photonic crystals

    PubMed Central

    Cheng, L; Anglin, E; Cunin, F; Kim, D; Sailor, M J; Falkenstein, I; Tammewar, A; Freeman, W R

    2009-01-01

    Aim To determine the suitability of porous silicon photonic crystals for intraocular drug-delivery. Methods A rugate structure was electrochemically etched into a highly doped p-type silicon substrate to create a porous silicon film that was subsequently removed and ultrasonically fractured into particles. To stabilise the particles in aqueous media, the silicon particles were modified by surface alkylation (using thermal hydrosilylation) or by thermal oxidation. Unmodified particles, hydrosilylated particles and oxidised particles were injected into rabbit vitreous. The stability and toxicity of each type of particle were studied by indirect ophthalmoscopy, biomicroscopy, tonometry, electroretinography (ERG) and histology. Results No toxicity was observed with any type of the particles during a period of >4 months. Surface alkylation led to dramatically increased intravitreal stability and slow degradation. The estimated vitreous half-life increased from 1 week (fresh particles) to 5 weeks (oxidised particles) and to 16 weeks (hydrosilylated particles). Conclusion The porous silicon photonic crystals showed good biocompatibility and may be used as an intraocular drug-delivery system. The intravitreal injectable porous silicon photonic crystals may be engineered to host a variety of therapeutics and achieve controlled drug release over long periods of time to treat chronic vitreoretinal diseases. PMID:18441177

  6. Silicon microdosimetry.

    PubMed

    Agosteo, Stefano; Pola, Andrea

    2011-02-01

    Silicon detectors are being studied as microdosemeters since they can provide sensitive volumes of micrometric dimensions. They can be applied for assessing single-event effects in electronic instrumentation exposed to complex fields around high-energy accelerators or in space missions. When coupled to tissue-equivalent converters, they can be used for measuring the quality of radiation therapy beams or for dosimetry. The use of micrometric volumes avoids the contribution of wall effects to the measured spectra. Further advantages of such detectors are their compactness, cheapness, transportability and a low sensitivity to vibrations. The following problems need to be solved when silicon devices are used for microdosimetry: (i) the sensitive volume has to be confined in a region of well-known dimensions; (ii) the electric noise limits the minimum detectable energy; (iii) corrections for tissue-equivalency should be made; (iv) corrections for shape equivalency should be made when referring to a spherical simulated site of tissue; (v) the angular response should be evaluated carefully; (vi) the efficiency of a single detector of micrometric dimensions is very poor and detector arrays should be considered. Several devices have been proposed as silicon microdosemeters, based on different technologies (telescope detectors, silicon on insulator detectors and arrays of cylindrical p-n junctions with internal amplification), in order to satisfy the issues mentioned above.

  7. Commissioning and operation of the CDF silicon detector

    SciTech Connect

    S. D'Auria

    2002-01-18

    The CDF-II silicon detector has been partially commissioned and used for taking preliminary physics data. This paper is a report on commissioning and initial operations of the 5.8m{sup 2} silicon detector. This experience can be useful to the large silicon systems that are presently under construction.

  8. Revealing of the transition from n- to p-type conduction of InN:Mg by photoconductivity effect measurement

    NASA Astrophysics Data System (ADS)

    Guo, L.; Wang, X. Q.; Zheng, X. T.; Yang, X. L.; Xu, F. J.; Tang, N.; Lu, L. W.; Ge, W. K.; Shen, B.; Dmowski, L. H.; Suski, T.

    2014-03-01

    We report evidence of the transition from n- to p-type conduction of InN with increasing Mg dopant concentration by using photoconductivity (PC) measurement at room temperature. This transition is depicted as a conversion from negative to positive PC under above-bandgap optical excitation. The n- to p-type transition in InN:Mg is further confirmed by thermopower measurements. PC detection method is a bulk effect since the optical absorption of the surface electron accumulation is negligibly low due to its rather small thickness, and thus shows advantage to detect p-type conduction. This technique is certainly helpful to study p-type doping of InN, which is still a subject of discussions.

  9. Revealing of the transition from n- to p-type conduction of InN:Mg by photoconductivity effect measurement.

    PubMed

    Guo, L; Wang, X Q; Zheng, X T; Yang, X L; Xu, F J; Tang, N; Lu, L W; Ge, W K; Shen, B; Dmowski, L H; Suski, T

    2014-03-13

    We report evidence of the transition from n- to p-type conduction of InN with increasing Mg dopant concentration by using photoconductivity (PC) measurement at room temperature. This transition is depicted as a conversion from negative to positive PC under above-bandgap optical excitation. The n- to p-type transition in InN:Mg is further confirmed by thermopower measurements. PC detection method is a bulk effect since the optical absorption of the surface electron accumulation is negligibly low due to its rather small thickness, and thus shows advantage to detect p-type conduction. This technique is certainly helpful to study p-type doping of InN, which is still a subject of discussions.

  10. Revealing of the transition from n- to p-type conduction of InN:Mg by photoconductivity effect measurement

    PubMed Central

    Guo, L.; Wang, X. Q.; Zheng, X. T.; Yang, X. L.; Xu, F. J.; Tang, N.; Lu, L. W.; Ge, W. K.; Shen, B.; Dmowski, L. H.; Suski, T.

    2014-01-01

    We report evidence of the transition from n- to p-type conduction of InN with increasing Mg dopant concentration by using photoconductivity (PC) measurement at room temperature. This transition is depicted as a conversion from negative to positive PC under above-bandgap optical excitation. The n- to p-type transition in InN:Mg is further confirmed by thermopower measurements. PC detection method is a bulk effect since the optical absorption of the surface electron accumulation is negligibly low due to its rather small thickness, and thus shows advantage to detect p-type conduction. This technique is certainly helpful to study p-type doping of InN, which is still a subject of discussions. PMID:24621830

  11. 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.

  12. Sputtering deposition of P-type SnO films with SnO₂ target in hydrogen-containing atmosphere.

    PubMed

    Hsu, Po-Ching; Hsu, Chao-Jui; Chang, Ching-Hsiang; Tsai, Shiao-Po; Chen, Wei-Chung; Hsieh, Hsing-Hung; Wu, Chung-Chih

    2014-08-27

    In this work, we had investigated sputtering deposition of p-type SnO using the widely used and robust SnO2 target in a hydrogen-containing reducing atmosphere. The effects of the hydrogen-containing sputtering gas on structures, compositions, optical, and electrical properties of deposited SnOx films were studied. Results show that polycrystalline and SnO-dominant films could be readily obtained by carefully controlling the hydrogen gas ratio in the sputtering gas and the extent of reduction reaction. P-type conductivity was unambiguously observed for SnO-dominant films with traceable Sn components, exhibiting a p-type Hall mobility of up to ∼3 cm(2) V(-1) s(-1). P-type SnO thin-film transistors using such SnO-dominant films were also demonstrated.

  13. Growth and Characterization of the p-type Semiconductors Tin Sulfide and Bismuth Copper Oxy Selenide

    NASA Astrophysics Data System (ADS)

    Francis, Jason

    BiCuOSe and SnS are layered, moderate band gap (epsilon G ≈ 1 eV) semiconductors that exhibit intrinsic p type conductivity. Doping of BiCuOSe with Ca results in a slight expansion of the lattice and an increase of the hole concentration from 10 18 cm--3 to greater than 1020 cm --3. The large carrier density in undoped films is the result of copper vacancies. Mobility is unaffected by doping, remaining constant at 1.5 cm2V--1s--1 in both undoped and doped films, because the Bi-O layers serve as the source of carriers, while transport occurs within the Cu-Se layers. Bi possesses a 6s2 lone pair that was expected to hybridize with the oxygen p states at the top of the valence band, resulting in high hole mobility as compared to similar materials such as LaCuOSe, which lack this lone pair. However, both LaCuOSe and BiCuOSe have similar hole mobility. X-ray absorption and emission spectroscopy, combined with density functional theory calculations, reveal that the Bi 6 s states contribute deep within the valence band, forming bonding and anti-bonding states with O 2p at 11 eV and 3 eV below the valence band maximum, respectively. Hence, the Bi lone pair does not contribute at the top of the valence band and does not enhance the hole mobility. The Bi 6p states contribute at the bottom of the conduction band, resulting in a smaller band gap for BiCuOSe than LaCuOSe (1 eV vs. 3 eV). SnS is a potential photovoltaic absorber composed of weakly coupled layers stacked along the long axis. This weak coupling results in the formation of strongly oriented films on amorphous substrates. The optical band gap is 1.2 eV, in agreement with GW calculations. Absorption reaches 105 cm--1 within 0.5 eV of the band gap. The p type conduction arises from energetically favorable tin vacancies. Variation of growth conditions yields carrier densities of 1014 -- 1016 cm--3 and hole mobility of 7 -- 15 cm2V--1s--1. SnS was alloyed with rocksalt CaS, which was predicted to form a rocksalt

  14. Purification and deposition of silicon by an iodide disproportionation reaction

    DOEpatents

    Wang, Tihu; Ciszek, Theodore F.

    2002-01-01

    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.

  15. Defect studies in copper-based p-type transparent conducting oxides

    NASA Astrophysics Data System (ADS)

    Ameena, Fnu

    Among other intrinsic open-volume defects, copper vacancy (VCu) has been theoretically identified as the major acceptor in p-type Cu-based semiconducting transparent oxides, which has potential as low-cost photovoltaic absorbers in semi-transparent solar cells. A series of positron annihilation experiments with pure Cu, Cu2O, and CuO presented strong presence of VCu and its complexes in the copper oxides. The lifetime data also showed that the density of VCu was becoming higher as the oxidation state of Cu increased which was consistent with the decrease in the formation energy of VCu. Doppler broadening measurements further indicated that electrons with low momentum made more contribution to the contributed as pure Cu oxidizes to copper oxides. The metastable defects are known to be generated in Cu2O upon illumination and it has been known to affect the performance of Cu2O-based hetero-junctions used in solar cells. The metastable effect was studied using positron annihilation lifetime spectroscopy and its data showed the change in the defect population upon light exposure and the minimal effect of light-induced electron density increase in the bulk of materials to the average lifetime of the positrons. The change in the defect population is concluded to be related to the dissociation and association of VCu -- V Cu complexes. For example, the shorter lifetime under light was ascribed to the annihilation with smaller size vacancies, which explains the dissociation of the complexes with light illumination. Doppler broadening of the annihilation was independent of light illumination, which suggested that the chemical nature of the defects remained without change upon their dissociation and association -- only the size distribution of copper vacancies varied. The delafossite metal oxides, CuMIIIO2 are emerging wide-bandgap p-type semiconductors. In this research, the formation energies of structural vacancies are calculated using Van Vechten cavity model as an attempt

  16. Few-Layer MoS₂ p-Type Devices Enabled by Selective Doping Using Low Energy Phosphorus Implantation.

    PubMed

    Nipane, Ankur; Karmakar, Debjani; Kaushik, Naveen; Karande, Shruti; Lodha, Saurabh

    2016-02-23

    P-type doping of MoS2 has proved to be a significant bottleneck in the realization of fundamental devices such as p-n junction diodes and p-type transistors due to its intrinsic n-type behavior. We report a CMOS compatible, controllable and area selective phosphorus plasma immersion ion implantation (PIII) process for p-type doping of MoS2. Physical characterization using SIMS, AFM, XRD and Raman techniques was used to identify process conditions with reduced lattice defects as well as low surface damage and etching, 4X lower than previous plasma based doping reports for MoS2. A wide range of nondegenerate to degenerate p-type doping is demonstrated in MoS2 field effect transistors exhibiting dominant hole transport. Nearly ideal and air stable, lateral homogeneous p-n junction diodes with a gate-tunable rectification ratio as high as 2 × 10(4) are demonstrated using area selective doping. Comparison of XPS data from unimplanted and implanted MoS2 layers shows a shift of 0.67 eV toward lower binding energies for Mo and S peaks indicating p-type doping. First-principles calculations using density functional theory techniques confirm p-type doping due to charge transfer originating from substitutional as well as physisorbed phosphorus in top few layers of MoS2. Pre-existing sulfur vacancies are shown to enhance the doping level significantly.

  17. N-Type delta Doping of High-Purity Silicon Imaging Arrays

    NASA Technical Reports Server (NTRS)

    Blacksberg, Jordana; Hoenk, Michael; Nikzad, Shouleh

    2005-01-01

    A process for n-type (electron-donor) delta doping has shown promise as a means of modifying back-illuminated image detectors made from n-doped high-purity silicon to enable them to detect high-energy photons (ultraviolet and x-rays) and low-energy charged particles (electrons and ions). This process is applicable to imaging detectors of several types, including charge-coupled devices, hybrid devices, and complementary metal oxide/semiconductor detector arrays. Delta doping is so named because its density-vs.-depth characteristic is reminiscent of the Dirac delta function (impulse function): the dopant is highly concentrated in a very thin layer. Preferably, the dopant is concentrated in one or at most two atomic layers in a crystal plane and, therefore, delta doping is also known as atomic-plane doping. The use of doping to enable detection of high-energy photons and low-energy particles was reported in several prior NASA Tech Briefs articles. As described in more detail in those articles, the main benefit afforded by delta doping of a back-illuminated silicon detector is to eliminate a "dead" layer at the back surface of the silicon wherein high-energy photons and low-energy particles are absorbed without detection. An additional benefit is that the delta-doped layer can serve as a back-side electrical contact. Delta doping of p-type silicon detectors is well established. The development of the present process addresses concerns specific to the delta doping of high-purity silicon detectors, which are typically n-type. The present process involves relatively low temperatures, is fully compatible with other processes used to fabricate the detectors, and does not entail interruption of those processes. Indeed, this process can be the last stage in the fabrication of an imaging detector that has, in all other respects, already been fully processed, including metallized. This process includes molecular-beam epitaxy (MBE) for deposition of three layers, including

  18. Theoretical considerations for Reaction-Formed Silicon Carbide (RFSC) formation by molten silicon infiltration into slurry-derived preforms

    NASA Technical Reports Server (NTRS)

    Behrendt, D. R.; Singh, M.

    1993-01-01

    For reaction-formed silicon carbide (RFSC) ceramics produced by silicon melt infiltration of porous carbon preforms, equations are developed to relate the amount of residual silicon to the initial carbon density. Also, for a slurry derived preform containing both carbon and silicon powder, equations are derived which relate the amount of residual silicon in the RFSC to the relative density of the carbon in the preform and to the amount of silicon powder added to the slurry. For a porous carbon preform that does not have enough porosity to prevent choking-off of the silicon infiltration, these results show that complete silicon infiltration can occur by adding silicon powder to the slurry mixture used to produce these preforms.

  19. Optically initiated silicon carbide high voltage switch

    DOEpatents

    Caporaso, George J [Livermore, CA; Sampayan, Stephen E [Manteca, CA; Sullivan, James S [Livermore, CA; Sanders,; David, M [Livermore, CA

    2011-02-22

    An improved photoconductive switch having a SiC or other wide band gap substrate material, such as GaAs and field-grading liners composed of preferably SiN formed on the substrate adjacent the electrode perimeters or adjacent the substrate perimeters for grading the electric fields.

  20. p-TYPE Nitrogen-Doped ZnO Microrods Preparation by Spray Pyrolysis

    NASA Astrophysics Data System (ADS)

    Zahedi, F.; Dariani, R. S.; Rozati, S. M.

    2012-10-01

    Nitrogen doped ZnO films with different N/Zn atomic ratio have been prepared by spray pyrolysis technique on glass substrate at 500°C. N/Zn atomic ratio has been selected 0, 0.5, 1, 2 and 3. The effect of N/Zn ratio on structural, optical and electrical properties has been investigated. Hall effect measurement studies show that the conductivity type of the films is affected by N/Zn ratio. The conductivity type of films changes from n for N/Zn = 0 and 0.5 to p for N/Zn = 1 and 2. Further increasing in N/Zn to 3 again led to n-type conductivity. p-type ZnO:N microrods film prepared with N/Zn = 1 has highest carrier concentration (1.36 × 1016 cm-3) and lowest resistivity (628 Ω.cm). All films are polycrystalline with hexagonal wurtzite structure. (002) plane is preferential orientation for all films. Surface morphology changes from rods to grains by increasing in N/Zn ratio. Optical transmission of the films increases with increasing in N/Zn ratio. Photoluminescence spectra at room temperature show the ultraviolet emission and two visible emissions at 440 nm and 520 nm. X-ray photoelectron spectroscopy analysis confirms the incorporation of nitrogen in ZnO:N film with N/Zn = 1.

  1. High-throughput search of ternary chalcogenides for p-type transparent electrodes.

    PubMed

    Shi, Jingming; Cerqueira, Tiago F T; Cui, Wenwen; Nogueira, Fernando; Botti, Silvana; Marques, Miguel A L

    2017-03-07

    Delafossite crystals are fascinating ternary oxides that have demonstrated transparent conductivity and ambipolar doping. Here we use a high-throughput approach based on density functional theory to find delafossite and related layered phases of composition ABX2, where A and B are elements of the periodic table, and X is a chalcogen (O, S, Se, and Te). From the 15 624 compounds studied in the trigonal delafossite prototype structure, 285 are within 50 meV/atom from the convex hull of stability. These compounds are further investigated using global structural prediction methods to obtain their lowest-energy crystal structure. We find 79 systems not present in the materials project database that are thermodynamically stable and crystallize in the delafossite or in closely related structures. These novel phases are then characterized by calculating their band gaps and hole effective masses. This characterization unveils a large diversity of properties, ranging from normal metals, magnetic metals, and some candidate compounds for p-type transparent electrodes.

  2. Interstitial oxygen as a source of p-type conductivity in hexagonal manganites

    PubMed Central

    Skjærvø, Sandra H.; Wefring, Espen T.; Nesdal, Silje K.; Gaukås, Nikolai H.; Olsen, Gerhard H.; Glaum, Julia; Tybell, Thomas; Selbach, Sverre M.

    2016-01-01

    Hexagonal manganites, h-RMnO3 (R=Sc, Y, Ho–Lu), have been intensively studied for their multiferroic properties, magnetoelectric coupling, topological defects and electrically conducting domain walls. Although point defects strongly affect the conductivity of transition metal oxides, the defect chemistry of h-RMnO3 has received little attention. We use a combination of experiments and first principles electronic structure calculations to elucidate the effect of interstitial oxygen anions, Oi, on the electrical and structural properties of h-YMnO3. Enthalpy stabilized interstitial oxygen anions are shown to be the main source of p-type electronic conductivity, without reducing the spontaneous ferroelectric polarization. A low energy barrier interstitialcy mechanism is inferred from Density Functional Theory calculations to be the microscopic migration path of Oi. Since the Oi content governs the concentration of charge carrier holes, controlling the thermal and atmospheric history provides a simple and fully reversible way of tuning the electrical properties of h-RMnO3. PMID:27924812

  3. High performance p-type NiOx thin-film transistor by Sn doping

    NASA Astrophysics Data System (ADS)

    Lin, Tengda; Li, Xiuling; Jang, Jin

    2016-06-01

    Major obstacles towards power efficient complementary electronics employing oxide thin-film transistors (TFTs) lie in the lack of equivalent well performing p-channel devices. Here, we report a significant performance enhancement of solution-processed p-type nickel oxide (NiOx) TFTs by introducing Sn dopant. The Sn-doped NiOx (Sn-NiOx) TFTs annealed at 280 °C demonstrate substantially improved electrical performances with the increase in the on/off current ratio (Ion/Ioff) by ˜100 times, field-effect mobility (μlin) by ˜3 times, and the decrease in subthreshold swing by half, comparing with those of pristine NiOx TFTs. X-ray photoelectron spectroscopy and X-ray diffraction results confirm that Sn atoms tend to substitute Ni sites and induce more amorphous phase. A decrease in density of states in the gap of NiOx by Sn doping and the shift of Fermi level (EF) into the midgap lead to the improvements of TFT performances. As a result, Sn-NiOx can be a promising material for the next-generation, oxide-based electronics.

  4. Alteration of P-type calcium channel gating by the spider toxin omega-Aga-IVA.

    PubMed Central

    McDonough, S I; Mintz, I M; Bean, B P

    1997-01-01

    We studied the mechanism of inhibition of P-type calcium channels in rat cerebellar Purkinje neurons by the peptide toxin omega-Aga-IVA. Saturating concentrations of omega-Aga-IVA (> 50 nM) inhibited inward current carried by 2-5 mM Ba almost completely. However, outward current at depolarizations of > +60 mV, carried by internal Cs, was inhibited much less, as was the tail current after such depolarizations. omega-Aga-IVA shifted the midpoint of the tail current activation curve by about +50 mV and made the curve less steep. The inactivation curve was also shifted in the depolarized direction and was made less steep. With omega-Aga-IVA, channels activated more slowly and deactivated more quickly than in control. Trains of repeated large depolarizations relieved the inhibition of current (as tested with moderate depolarizations), probably reflecting the unbinding of toxin. The relief of inhibition was faster with increasing depolarization, but did not require internal permeant ions. We conclude that omega-Aga-IVA alters voltage-dependent gating by stabilizing closed states of the channel and that omega-Aga-IVA dissociates much more rapidly from open channels than from closed. PMID:9129813

  5. High-throughput search of ternary chalcogenides for p-type transparent electrodes

    NASA Astrophysics Data System (ADS)

    Shi, Jingming; Cerqueira, Tiago F. T.; Cui, Wenwen; Nogueira, Fernando; Botti, Silvana; Marques, Miguel A. L.

    2017-03-01

    Delafossite crystals are fascinating ternary oxides that have demonstrated transparent conductivity and ambipolar doping. Here we use a high-throughput approach based on density functional theory to find delafossite and related layered phases of composition ABX2, where A and B are elements of the periodic table, and X is a chalcogen (O, S, Se, and Te). From the 15 624 compounds studied in the trigonal delafossite prototype structure, 285 are within 50 meV/atom from the convex hull of stability. These compounds are further investigated using global structural prediction methods to obtain their lowest-energy crystal structure. We find 79 systems not present in the materials project database that are thermodynamically stable and crystallize in the delafossite or in closely related structures. These novel phases are then characterized by calculating their band gaps and hole effective masses. This characterization unveils a large diversity of properties, ranging from normal metals, magnetic metals, and some candidate compounds for p-type transparent electrodes.

  6. Quasiparticle band structures and thermoelectric transport properties of p-type SnSe

    SciTech Connect

    Shi, Guangsha; Kioupakis, Emmanouil

    2015-02-14

    We used density functional and many-body perturbation theory to calculate the quasiparticle band structures and electronic transport parameters of p-type SnSe both for the low-temperature Pnma and high-temperature Cmcm phases. The Pnma phase has an indirect band gap of 0.829 eV, while the Cmcm has a direct band gap of 0.464 eV. Both phases exhibit multiple local band extrema within an energy range comparable to the thermal energy of carriers from the global extrema. We calculated the electronic transport coefficients as a function of doping concentration and temperature for single-crystal and polycrystalline materials to understand the previous experimental measurements. The electronic transport coefficients are highly anisotropic and are strongly affected by bipolar transport effects at high temperature. Our results indicate that SnSe exhibits optimal thermoelectric performance at high temperature when doped in the 10{sup 19}–10{sup 20 }cm{sup −3} range.

  7. Growth of p-type ZnOS films by pulsed laser deposition

    NASA Astrophysics Data System (ADS)

    Kobayashi, Kenkichiro; Ohtsuki, Tohru; Tomita, Yasumasa; Kohno, Yosiumi; Maeda, Yasuhisa; Matsushima, Shigenori

    2017-01-01

    ZnO1-xSx films were deposited on quartz substrates by pulsed laser deposition (PLD) of ZnO1-xSx targets. The ZnO1-xSx films with S-contents of 0.03-0.17 were grown from the ZnO1-xSx targets sulfured at temperatures of 200 and 500 °C. The resistivity of the ZnO1-xSx films is slightly increased with the S-content. An increase of the O2-partial pressure in an atmosphere reduces the S-content in the films and drastically enhances the resistivity of the films. However, the carrier type of the films is still n-type. In order to incorporate excess S atoms into films, evaporation of Sulfur was performed during the PLD process. As a temperature of the S-evaporation is raised, the resistivity of the films is significantly enhanced and hole-conductivity appears in the films grown by the S-evaporation at 80 and 90 °C. By X-ray photoelectron spectroscopic measurements, the presence of SOx species is confirmed for the p-type ZnO1-xSx film. Both interstitial SO3 or SO4 clusters and complexes of Zn-vacancy with H are considered to be appropriate acceptors responsible for the hole-conductivity at room temperature.

  8. High-throughput search of ternary chalcogenides for p-type transparent electrodes

    PubMed Central

    Shi, Jingming; Cerqueira, Tiago F. T.; Cui, Wenwen; Nogueira, Fernando; Botti, Silvana; Marques, Miguel A. L.

    2017-01-01

    Delafossite crystals are fascinating ternary oxides that have demonstrated transparent conductivity and ambipolar doping. Here we use a high-throughput approach based on density functional theory to find delafossite and related layered phases of composition ABX2, where A and B are elements of the periodic table, and X is a chalcogen (O, S, Se, and Te). From the 15 624 compounds studied in the trigonal delafossite prototype structure, 285 are within 50 meV/atom from the convex hull of stability. These compounds are further investigated using global structural prediction methods to obtain their lowest-energy crystal structure. We find 79 systems not present in the materials project database that are thermodynamically stable and crystallize in the delafossite or in closely related structures. These novel phases are then characterized by calculating their band gaps and hole effective masses. This characterization unveils a large diversity of properties, ranging from normal metals, magnetic metals, and some candidate compounds for p-type transparent electrodes. PMID:28266587

  9. P-type InGaAsP coolers for integrated optic devices

    NASA Astrophysics Data System (ADS)

    Vashaee, Daryoosh; LaBounty, Christopher J.; Fang, Xiaofeng; Zeng, Gehong; Abraham, Patrick; Bowers, John E.; Shakouri, Ali

    2001-05-01

    Single stage thin film coolers based on thermoelectric and thermionic cooling in p-type InGaAsP superlattice structures have been fabricated. Devices with different sizes and at various ambient temperatures have been characterized. Experimental results showed 0.5 degree centigrade cooling below the ambient temperature at 25C. This cooling over 1 4mu2m thick superlattice barrier corresponds to cooling power densities on the order of 200 W/cm2. The device cools by a factor of two better at higher temperatures (70C). This is due to the reduction of the superlattice thermal conductivity and the broadening of the electronic distribution function at higher temperatures. 150x150 micrometers 2 devices provide largest cooling at room temperature while the optimum device size shrinks as the temperature increases. Simulations results that take into account finite thermal resistance of the InP substrate, the effect of the contact resistance, heat generation in the wire-bonds and metallic pads on top of the device predict accurately the optimum cooling of these micro refrigerators. By eliminating the major parasitic sources of heating (Joule heating in the substrate, heat conduction through the side contact and reducing the contact resistance to 5x7-7 ohm-cm2) simulations show that, ultimately, one can achieve 15 degree(s)C cooling (10's of kW/cm2 cooling power) with single stage p-InGaAsP thin film coolers.

  10. Raman Spectroscopy Determination of Hole Concentration in p-Type GaSb

    SciTech Connect

    Maslar JE, Hurst WS, Wang CA

    2007-04-05

    Room temperature p-type GaSb bulk coupled mode spectra were measured as a function of hole concentration. These spectra were obtained using an optical system based on 752.55 nm excitation in order to obtain more sensitivity to bulk GaSb coupled mode scattering than possible with visible wavelength excitation-based systems. A relatively simple spectral model for the electronic contribution to the dielectric function was evaluated for determination of hole concentration from the bulk coupled mode spectra. Optically-derived values for hole concentration were determined by minimizing the sum of the residuals squared between an experimental and simulated spectrum as a function of total hole concentration and a plasmon damping parameter. Hole concentrations obtained from the Raman spectroscopic measurements deviated from the values determined from single field Hall effect measurements that were corrected to account for two band conduction by {approx}20% to {approx}65%. These deviations were attributed to the limitations of the spectral model employed and uncertainties in GaSb materials properties.

  11. ZnTe Alloying Effect on Enhanced Thermoelectric Properties of p-Type PbTe.

    PubMed

    Ahn, Kyunghan; Shin, Hocheol; Im, Jino; Park, Sang Hyun; Chung, In

    2017-02-01

    We investigate the effect of ZnTe incorporation on PbTe to enhance thermoelectric performance. We report structural, microscopic, and spectroscopic characterizations, ab initio theoretical calculations, and thermoelectric transport properties of Pb0.985Na0.015Te-x% ZnTe (x = 0, 1, 2, 4). We find that the solid solubility limit of ZnTe in PbTe is less than 1 mol %. The introduction of 2% ZnTe in p-type Pb0.985Na0.015Te reduces the lattice thermal conductivity through the ZnTe precipitates at the microscale. Consequently, a maximum thermoelectric figure of merit (ZT) of 1.73 at 700 K is achieved for the spark plasma-sintered Pb0.985Na0.015Te-2% ZnTe, which arises from a decreased lattice thermal conductivity of ∼0.69 W m(-1) K(-1) at ∼700 K in comparison with Pb0.985Na0.015Te.

  12. Heavy hole effect on the thermoelectric properties of highly doped p-type lead telluride

    NASA Astrophysics Data System (ADS)

    Babenko, N. I.; Dmitriev, A. V.

    2017-01-01

    We study theoretically the thermoelectric properties of heavily doped p-type PbTe in the temperature interval of 300 to 900 K. In our calculations, we use the three-band model of PbTe electron energy spectrum that takes into account the heavy-hole Σ-band. On the base of the Boltzmann kinetic equation, the full set of the relevant kinetic characteristics is calculated including the electrical and thermal conductivities, the Seebeck coefficient, and the thermoelectric figure-of-merit. The thermoelectric characteristics appear to be very sensitive to parameters of the heavy hole band. The best fit with experiment was obtained at mh h=5 m0 and Eg Σ=0.5 eV. All calculated thermoelectric quantities then agree very well with the available experimental data. In particular, we were able to reproduce the significant increase of the figure-of-merit up to Z T ≈1.2 that was experimentally observed recently in heavily p-doped PbTe. Our results show that ZT maximum corresponds to the temperature wherein the light hole and heavy hole band edges coincide so that a prominent density-of-states singularity is formed in the valence band.

  13. Photoluminescence studies of compensated p-type ZnSe:N(P) under hydrostatic pressure

    NASA Astrophysics Data System (ADS)

    Kuskovsky, Igor; Neumark, G. F.; Tischler, J.; Iota, V.; Weinstein, B. A.

    2000-03-01

    It is well known that to this day p-type ZnSe, even with the best acceptor dopant, nitrogen, can not be doped higher than 10^18 cm-3, even with a 100% acceptor activation ratio. The knowledge of the defect structure of highly doped and compensated ZnSe:N can help to understand this limitation. We report here the results of PL studies done under hydrostatic pressure. We have found the presence of a resonant donor defect in heavily doped and compensated ZnSe:N; this donor has a level of ~20-140 meV above the conduction band edge at ambient pressure. The red-shifted donor-acceptor-pair photoluminescence observed in these samples is quenched by the resonant defect for pressures higher than ~25 kbar. A split N-N interstitial on a Se site is discussed as a reasonable candidate for such a defect. Auger recombination is proposed as a quenching mechanism. These findings are compared with earlier results on intermediately doped ZnSe:N, and with data on compensated ZnSe:P. We suggest that, for high doping, the similar PL quenching seen above ~30kbar in ZnSe:P could be due to an analogous donor defect. Two of the authors (IK & GFN) acknowledge support from DOE grant DE-FG02-98ER45694

  14. High-Performance p-Type Black Phosphorus Transistor with Scandium Contact.

    PubMed

    Li, Ling; Engel, Michael; Farmer, Damon B; Han, Shu-Jen; Wong, H-S Philip

    2016-04-26

    A record high current density of 580 μA/μm is achieved for long-channel, few-layer black phosphorus transistors with scandium contacts after 400 K vacuum annealing. The annealing effectively improves the on-state current and Ion/Ioff ratio by 1 order of magnitude and the subthreshold swing by ∼2.5×, whereas Al2O3 capping significantly degrades transistor performances, resulting in 5× lower on-state current and 3× lower Ion/Ioff ratio. The influences of moisture on black phosphorus metal contacts are elucidated by analyzing the hysteresis of 3-20 nm thick black phosphorus transistors with scandium and gold contacts under different conditions: as-fabricated, after vacuum annealing, and after Al2O3 capping. The optimal black phosphorus film thickness for transistors with scandium contacts is found to be ∼10 nm. Moreover, p-type performance is shown in all transistors with scandium contacts, suggesting that the Fermi level is pinned closer to the valence band regardless of the flake thickness.

  15. Observations of exciton and carrier spin relaxation in Be doped p-type GaAs

    SciTech Connect

    Asaka, Naohiro; Harasawa, Ryo; Tackeuchi, Atsushi; Lu, Shulong; Dai, Pan

    2014-03-17

    We have investigated the exciton and carrier spin relaxation in Be-doped p-type GaAs. Time-resolved spin-dependent photoluminescence (PL) measurements revealed spin relaxation behaviors between 10 and 100 K. Two PL peaks were observed at 1.511 eV (peak 1) and 1.497 eV (peak 2) at 10 K, and are attributed to the recombination of excitons bound to neutral Be acceptors (peak 1) and the band-to-acceptor transition (peak 2). The spin relaxation times of both PL peaks were measured to be 1.3–3.1 ns at 10–100 K, and found to originate from common electron spin relaxation. The observed existence of a carrier density dependence of the spin relaxation time at 10–77 K indicates that the Bir-Aronov-Pikus process is the dominant spin relaxation mechanism.

  16. Ferromagnetic ordering of Cr and Fe doped p-type diamond: An ab initio study

    SciTech Connect

    Benecha, E. M.; Lombardi, E. B.

    2014-02-21

    Ferromagnetic ordering of transition metal dopants in semiconductors holds the prospect of combining the capabilities of semiconductors and magnetic systems in single hybrid devices for spintronic applications. Various semiconductors have so far been considered for spintronic applications, but low Curie temperatures have hindered room temperature applications. We report ab initio DFT calculations on the stability and magnetic properties of Fe and Cr impurities in diamond, and show that their ground state magnetic ordering and stabilization energies depend strongly on the charge state and type of co-doping. We predict that divacancy Cr{sup +2} and substitutional Fe{sup +1} order ferromagnetically in p-type diamond, with magnetic stabilization energies (and magnetic moment per impurity ion) of 16.9 meV (2.5 μ{sub B}) and 33.3 meV (1.0 μ{sub B}), respectively. These magnetic stabilization energies are much larger than what has been achieved in other semiconductors at comparable impurity concentrations, including the archetypal dilute magnetic semiconductor GaAs:Mn. In addition, substitutional Fe{sup +1} exhibits a strong half-metallic character, with the Fermi level crossing bands in only the spin down channel. These results, combined with diamond’s extreme properties, demonstrate that Cr or Fe dopedp-type diamond may successfully be considered in the search for room temperature spintronic materials.

  17. Towards P-Type Conductivity in SnO2 Nanocrystals through Li Doping

    SciTech Connect

    Chaparadza, Allen; Rananavare, Shankar B

    2010-01-22

    This paper examines electrical transport properties and Li doping in SnO2 synthesized by the sol–gel method. Solid-state 7Li-NMR lineshapes reveal that Li ions occupy two distinct sites with differing dynamic mobilities. The chemical exchange rate between the two sites is, however, too slow for detection on the NMR timescale. Compressed nanoparticulate films of this doped semiconductor exhibit a positive Seebeck coefficient implying a p-type conductivity. A variable-temperature direct current conductivity, over a 25–350 °C temperature range, follows an Efros–Shklovskii variable range hopping (ES-VRH) conduction mechanism (ln(ρ) versus T -1/2) at temperatures below 100 °C with a crossover to 2D Mott variable range hopping (M-VRH) (ln(ρ) versus T -1/3) conduction at temperatures above 250 °C. In a transition region between these two limiting behaviors, the dc resistivity exhibits an anomalous temperature-independent plateau. We suggest that its origin may lie in a carrier inversion phenomenon wherein the majority carriers switch from holes to electrons due to Li ion expulsion from the crystalline core and creation of oxygen vacancies generated by loss of oxygen at elevated temperatures.

  18. Enhanced thermoelectric figure of merit of p-type half-Heuslers.

    PubMed

    Yan, Xiao; Joshi, Giri; Liu, Weishu; Lan, Yucheng; Wang, Hui; Lee, Sangyeop; Simonson, J W; Poon, S J; Tritt, T M; Chen, Gang; Ren, Z F

    2011-02-09

    Half-Heuslers would be important thermoelectric materials due to their high temperature stability and abundance if their dimensionless thermoelectric figure of merit (ZT) could be made high enough. The highest peak ZT of a p-type half-Heusler has been so far reported about 0.5 due to the high thermal conductivity. Through a nanocomposite approach using ball milling and hot pressing, we have achieved a peak ZT of 0.8 at 700 °C, which is about 60% higher than the best reported 0.5 and might be good enough for consideration for waste heat recovery in car exhaust systems. The improvement comes from a simultaneous increase in Seebeck coefficient and a significant decrease in thermal conductivity due to nanostructures. The samples were made by first forming alloyed ingots using arc melting and then creating nanopowders by ball milling the ingots and finally obtaining dense bulk by hot pressing. Further improvement in ZT is expected when average grain sizes are made smaller than 100 nm.

  19. Ferromagnetic ordering of Cr and Fe doped p-type diamond: An ab initio study

    NASA Astrophysics Data System (ADS)

    Benecha, E. M.; Lombardi, E. B.

    2014-02-01

    Ferromagnetic ordering of transition metal dopants in semiconductors holds the prospect of combining the capabilities of semiconductors and magnetic systems in single hybrid devices for spintronic applications. Various semiconductors have so far been considered for spintronic applications, but low Curie temperatures have hindered room temperature applications. We report ab initio DFT calculations on the stability and magnetic properties of Fe and Cr impurities in diamond, and show that their ground state magnetic ordering and stabilization energies depend strongly on the charge state and type of co-doping. We predict that divacancy Cr+2 and substitutional Fe+1 order ferromagnetically in p-type diamond, with magnetic stabilization energies (and magnetic moment per impurity ion) of 16.9 meV (2.5 μB) and 33.3 meV (1.0 μB), respectively. These magnetic stabilization energies are much larger than what has been achieved in other semiconductors at comparable impurity concentrations, including the archetypal dilute magnetic semiconductor GaAs:Mn. In addition, substitutional Fe+1 exhibits a strong half-metallic character, with the Fermi level crossing bands in only the spin down channel. These results, combined with diamond's extreme properties, demonstrate that Cr or Fe dopedp-type diamond may successfully be considered in the search for room temperature spintronic materials.

  20. Near Field Enhanced Photocurrent Generation in P-type Dye-Sensitized Solar Cells

    PubMed Central

    Xu, Xiaobao; Cui, Jin; Han, Junbo; Zhang, Junpei; Zhang, Yibo; Luan, Lin; Alemu, Getachew; Wang, Zhong; Shen, Yan; Xiong, Dehua; Chen, Wei; Wei, Zhanhua; Yang, Shihe; Hu, Bin; Cheng, Yibing; Wang, Mingkui

    2014-01-01

    Over the past few decades, the field of p-type dye-sensitized solar cell (p-DSSC) devices has undergone tremendous advances, in which Cu-based delafossite nanocrystal is of prime interest. This paper presents an augment of about 87% improvement in photocurrent observed in a particular configuration of organic dye P1 sensitized CuCrO2 delafossite nanocrystal electrode coupled with organic redox shuttle, 1-methy-1H- tetrazole-5-thiolate and its disulfide dimer when Au nanoparticles (NPs, with diameter of about 20 nm) is added into the photocathode, achieving a power convert efficiency of 0.31% (measured under standard AM 1.5 G test conditions). Detailed investigation shows that the local electrical-magnetic field effect, induced by Au NPs among the mesoporous CuCrO2 film, can improve the charge injection efficiency at dye/semiconductor interface, which is responsible for the bulk of the gain in photocurrent. PMID:24492539

  1. Plasmodium P-Type Cyclin CYC3 Modulates Endomitotic Growth during Oocyst Development in Mosquitoes.

    PubMed

    Roques, Magali; Wall, Richard J; Douglass, Alexander P; Ramaprasad, Abhinay; Ferguson, David J P; Kaindama, Mbinda L; Brusini, Lorenzo; Joshi, Nimitray; Rchiad, Zineb; Brady, Declan; Guttery, David S; Wheatley, Sally P; Yamano, Hiroyuki; Holder, Anthony A; Pain, Arnab; Wickstead, Bill; Tewari, Rita

    2015-11-01

    Cell-cycle progression and cell division in eukaryotes are governed in part by the cyclin family and their regulation of cyclin-dependent kinases (CDKs). Cyclins are very well characterised in model systems such as yeast and human cells, but surprisingly little is known about their number and role in Plasmodium, the unicellular protozoan parasite that causes malaria. Malaria parasite cell division and proliferation differs from that of many eukaryotes. During its life cycle it undergoes two types of mitosis: endomitosis in asexual stages and an extremely rapid mitotic process during male gametogenesis. Both schizogony (producing merozoites) in host liver and red blood cells, and sporogony (producing sporozoites) in the mosquito vector, are endomitotic with repeated nuclear replication, without chromosome condensation, before cell division. The role of specific cyclins during Plasmodium cell proliferation was unknown. We show here that the Plasmodium genome contains only three cyclin genes, representing an unusual repertoire of cyclin classes. Expression and reverse genetic analyses of the single Plant (P)-type cyclin, CYC3, in the rodent malaria parasite, Plasmodium berghei, revealed a cytoplasmic and nuclear location of the GFP-tagged protein throughout the lifecycle. Deletion of cyc3 resulted in defects in size, number and growth of oocysts, with abnormalities in budding and sporozoite formation. Furthermore, global transcript analysis of the cyc3-deleted and wild type parasites at gametocyte and ookinete stages identified differentially expressed genes required for signalling, invasion and oocyst development. Collectively these data suggest that cyc3 modulates oocyst endomitotic development in Plasmodium berghei.

  2. Interstitial oxygen as a source of p-type conductivity in hexagonal manganites

    NASA Astrophysics Data System (ADS)

    Skjærvø, Sandra H.; Wefring, Espen T.; Nesdal, Silje K.; Gaukås, Nikolai H.; Olsen, Gerhard H.; Glaum, Julia; Tybell, Thomas; Selbach, Sverre M.

    2016-12-01

    Hexagonal manganites, h-RMnO3 (R=Sc, Y, Ho-Lu), have been intensively studied for their multiferroic properties, magnetoelectric coupling, topological defects and electrically conducting domain walls. Although point defects strongly affect the conductivity of transition metal oxides, the defect chemistry of h-RMnO3 has received little attention. We use a combination of experiments and first principles electronic structure calculations to elucidate the effect of interstitial oxygen anions, Oi, on the electrical and structural properties of h-YMnO3. Enthalpy stabilized interstitial oxygen anions are shown to be the main source of p-type electronic conductivity, without reducing the spontaneous ferroelectric polarization. A low energy barrier interstitialcy mechanism is inferred from Density Functional Theory calculations to be the microscopic migration path of Oi. Since the Oi content governs the concentration of charge carrier holes, controlling the thermal and atmospheric history provides a simple and fully reversible way of tuning the electrical properties of h-RMnO3.

  3. SIM Lite Detection of Habitable Planets in P-Type Binary-Planetary Systems

    NASA Technical Reports Server (NTRS)

    Pan, Xiaopei; Shao, Michael; Shaklan, Stuart; Goullioud, Renaud

    2010-01-01

    Close binary stars like spectroscopic binaries create a completely different environment than single stars for the evolution of a protoplanetary disk. Dynamical interactions between one star and protoplanets in such systems provide more challenges for theorists to model giant planet migration and formation of multiple planets. For habitable planets the majority of host stars are in binary star systems. So far only a small amount of Jupiter-size planets have been discovered in binary stars, whose minimum separations are 20 AU and the median value is about 1000 AU (because of difficulties in radial velocity measurements). The SIM Lite mission, a space-based astrometric observatory, has a unique capability to detect habitable planets in binary star systems. This work analyzed responses of the optical system to the field stop for companion stars and demonstrated that SIM Lite can observe exoplanets in visual binaries with small angular separations. In particular we investigated the issues for the search for terrestrial planets in P-type binary-planetary systems, where the planets move around both stars in a relatively distant orbit.

  4. Growth of antimony doped P-type zinc oxide nanowires for optoelectronics

    DOEpatents

    Wang, Zhong Lin; Pradel, Ken

    2016-09-27

    In a method of growing p-type nanowires, a nanowire growth solution of zinc nitrate (Zn(NO.sub.3).sub.2), hexamethylenetetramine (HMTA) and polyethylenemine (800 M.sub.w PEI) is prepared. A dopant solution to the growth solution, the dopant solution including an equal molar ration of sodium hydroxide (NaOH), glycolic acid (C.sub.2H.sub.4O.sub.3) and antimony acetate (Sb(CH.sub.3COO).sub.3) in water is prepared. The dopant solution and the growth solution combine to generate a resulting solution that includes antimony to zinc in a ratio of between 0.2% molar to 2.0% molar, the resulting solution having a top surface. An ammonia solution is added to the resulting solution. A ZnO seed layer is applied to a substrate and the substrate is placed into the top surface of the resulting solution with the ZnO seed layer facing downwardly for a predetermined time until Sb-doped ZnO nanowires having a length of at least 5 .mu.m have grown from the ZnO seed layer.

  5. Improved source design for p-type tunnel field-effect transistors: Towards truly complementary logic

    SciTech Connect

    Verreck, Devin Groeseneken, Guido; Verhulst, Anne S.; Collaert, Nadine; Mocuta, Anda; Thean, Aaron; Sorée, Bart

    2014-12-15

    Complementary logic based on tunnel field-effect transistors (TFETs) would drastically reduce power consumption thanks to the TFET's potential to obtain a sub-60 mV/dec subthreshold swing (SS). However, p-type TFETs typically do not meet the performance of n-TFETs for direct bandgap III-V configurations. The p-TFET SS stays well above 60 mV/dec, due to the low density of states in the conduction band. We therefore propose a source configuration in which a highly doped region is maintained only near the tunnel junction. In the remaining part of the source, the hot carriers in the exponential tail of the Fermi-Dirac distribution are blocked by reducing the doping degeneracy, either with a source section with a lower doping concentration or with a heterostructure. We apply this concept to n-p-i-p configurations consisting of In{sub 0.53}Ga{sub 0.47}As and an InP-InAs heterostructure. 15-band quantum mechanical simulations predict that the configurations with our source design can obtain sub-60 mV/dec SS, with an on-current comparable to the conventional source design.

  6. Analysis of Radiation Effects in Silicon using Kinetic Monte Carlo Methods

    DOE PAGES

    Hehr, Brian Douglas

    2014-11-25

    The transient degradation of semiconductor device performance under irradiation has long been an issue of concern. Neutron irradiation can instigate the formation of quasi-stable defect structures, thereby introducing new energy levels into the bandgap that alter carrier lifetimes and give rise to such phenomena as gain degradation in bipolar junction transistors. Normally, the initial defect formation phase is followed by a recovery phase in which defect-defect or defect-dopant interactions modify the characteristics of the damaged structure. A kinetic Monte Carlo (KMC) code has been developed to model both thermal and carrier injection annealing of initial defect structures in semiconductor materials.more » The code is employed to investigate annealing in electron-irradiated, p-type silicon as well as the recovery of base current in silicon transistors bombarded with neutrons at the Los Alamos Neutron Science Center (LANSCE) “Blue Room” facility. Our results reveal that KMC calculations agree well with these experiments once adjustments are made, within the appropriate uncertainty bounds, to some of the sensitive defect parameters.« less

  7. Analysis of Radiation Effects in Silicon using Kinetic Monte Carlo Methods

    SciTech Connect

    Hehr, Brian Douglas

    2014-11-25

    The transient degradation of semiconductor device performance under irradiation has long been an issue of concern. Neutron irradiation can instigate the formation of quasi-stable defect structures, thereby introducing new energy levels into the bandgap that alter carrier lifetimes and give rise to such phenomena as gain degradation in bipolar junction transistors. Normally, the initial defect formation phase is followed by a recovery phase in which defect-defect or defect-dopant interactions modify the characteristics of the damaged structure. A kinetic Monte Carlo (KMC) code has been developed to model both thermal and carrier injection annealing of initial defect structures in semiconductor materials. The code is employed to investigate annealing in electron-irradiated, p-type silicon as well as the recovery of base current in silicon transistors bombarded with neutrons at the Los Alamos Neutron Science Center (LANSCE) “Blue Room” facility. Our results reveal that KMC calculations agree well with these experiments once adjustments are made, within the appropriate uncertainty bounds, to some of the sensitive defect parameters.

  8. Rapid Solid-State Metathesis Routes to Nanostructured Silicon-Germainum

    NASA Technical Reports Server (NTRS)

    Kaner, Richard B. (Inventor); Bux, Sabah K. (Inventor); Fleurial, Jean-Pierre (Inventor); Rodriguez, Marc (Inventor)

    2014-01-01

    Methods for producing nanostructured silicon and silicon-germanium via solid state metathesis (SSM). The method of forming nanostructured silicon comprises the steps of combining a stoichiometric mixture of silicon tetraiodide (SiI4) and an alkaline earth metal silicide into a homogeneous powder, and initating the reaction between the silicon tetraiodide (SiI4) with the alkaline earth metal silicide. The method of forming nanostructured silicon-germanium comprises the steps of combining a stoichiometric mixture of silicon tetraiodide (SiI4) and a germanium based precursor into a homogeneous powder, and initiating the reaction between the silicon tetraiodide (SiI4) with the germanium based precursors.

  9. Silicon production process evaluations

    NASA Technical Reports Server (NTRS)

    1981-01-01

    Chemical engineering analysis of the HSC process (Hemlock Semiconductor Corporation) for producing silicon from dichlorosilane in a 1,000 MT/yr plant was continued. Progress and status for the chemical engineering analysis of the HSC process are reported for the primary process design engineering activities: base case conditions (85%), reaction chemistry (85%), process flow diagram (60%), material balance (60%), energy balance (30%), property data (30%), equipment design (20%) and major equipment list (10%). Engineering design of the initial distillation column (D-01, stripper column) in the process was initiated. The function of the distillation column is to remove volatile gases (such as hydrogen and nitrogen) which are dissolved in liquid chlorosilanes. Initial specifications and results for the distillation column design are reported including the variation of tray requirements (equilibrium stages) with reflux ratio for the distillation.

  10. Role of point defects/defect complexes in silicon device processing. Book of abstracts, fourth workshop

    SciTech Connect

    Not Available

    1994-06-01

    The 41 abstracts are arranged into 6 sessions: impurities and defects in commercial substrates: their sources, effects on material yield, and material quality; impurity gettering in silicon: limits and manufacturability of impurity gettering and in silicon solar cells; impurity/defect passivation; new concepts in silicon growth: improved initial quality and thin films; and silicon solar cell design opportunities.

  11. Realization of Cu-Doped p-Type ZnO Thin Films by Molecular Beam Epitaxy.

    PubMed

    Suja, Mohammad; Bashar, Sunayna B; Morshed, Muhammad M; Liu, Jianlin

    2015-04-29

    Cu-doped p-type ZnO films are grown on c-sapphire substrates by plasma-assisted molecular beam epitaxy. Photoluminescence (PL) experiments reveal a shallow acceptor state at 0.15 eV above the valence band edge. Hall effect results indicate that a growth condition window is found for the formation of p-type ZnO thin films, and the best conductivity is achieved with a high hole concentration of 1.54 × 10(18) cm(-3), a low resistivity of 0.6 Ω cm, and a moderate mobility of 6.65 cm(2) V(-1) s(-1) at room temperature. Metal oxide semiconductor capacitor devices have been fabricated on the Cu-doped ZnO films, and the characteristics of capacitance-voltage measurements demonstrate that the Cu-doped ZnO thin films under proper growth conditions are p-type. Seebeck measurements on these Cu-doped ZnO samples lead to positive Seebeck coefficients and further confirm the p-type conductivity. Other measurements such as X-ray diffraction, X-ray photoelectron, Raman, and absorption spectroscopies are also performed to elucidate the structural and optical characteristics of the Cu-doped p-type ZnO films. The p-type conductivity is explained to originate from Cu substitution of Zn with a valency of +1 state. However, all p-type samples are converted to n-type over time, which is mostly due to the carrier compensation from extrinsic defects of ZnO.

  12. Evaluation of transition metal oxide as carrier-selective contacts for silicon heterojunction solar cells

    SciTech Connect

    Ding, L.; Boccard, Matthieu; Holman, Zachary; Bertoni, M.

    2015-04-06

    "Reducing light absorption in the non-active solar cell layers, while enabling the extraction of the photogenerated minority carriers at quasi-Fermi levels are two key factors to improve current generation and voltage, and therefore efficiency of silicon heterojunction solar devices. To address these two critical aspects, transition metal oxide materials have been proposed as alternative to the n- and p-type amorphous silicon used as electron and hole selective contacts, respectively. Indeed, transition metal oxides such as molybdenum oxide, titanium oxide, nickel oxide or tungsten oxide combine a wide band gap typically over 3 eV with a band structure and theoretical band alignment with silicon that results in high transparency to the solar spectrum and in selectivity for the transport of only one carrier type. Improving carrier extraction or injection using transition metal oxide has been a topic of investigation in the field of organic solar cells and organic LEDs; from these pioneering works a lot of knowledge has been gained on materials properties, ways to control these during synthesis and deposition, and their impact on device performance. Recently, the transfer of some of this knowledge to silicon solar cells and the successful application of some metal oxide to contact heterojunction devices have gained much attention. In this contribution, we investigate the suitability of various transition metal oxide films (molybdenum oxide, titanium oxide, and tungsten oxide) deposited either by thermal evaporation or sputtering as transparent hole or electron selective transport layer for silicon solar cells. In addition to systematically characterize their optical and structural properties, we use photoemission spectroscopy to relate compound stoichiometry to band structure and characterize band alignment to silicon. The direct silicon/metal oxide interface is further analyzed by quasi-steady state photoconductance decay method to assess the quality of surface

  13. 22.5% efficient silicon heterojunction solar cell with molybdenum oxide hole collector

    SciTech Connect

    Geissbühler, Jonas Werner, Jérémie; Martin de Nicolas, Silvia; Hessler-Wyser, Aïcha; Tomasi, Andrea; Niesen, Bjoern; De Wolf, Stefaan; Barraud, Loris; Despeisse, Matthieu; Nicolay, Sylvain; Ballif, Christophe

    2015-08-24

    Substituting the doped amorphous silicon films at the front of silicon heterojunction solar cells with wide-bandgap transition metal oxides can mitigate parasitic light absorption losses. This was recently proven by replacing p-type amorphous silicon with molybdenum oxide films. In this article, we evidence that annealing above 130 °C—often needed for the curing of printed metal contacts—detrimentally impacts hole collection of such devices. We circumvent this issue by using electrodeposited copper front metallization and demonstrate a silicon heterojunction solar cell with molybdenum oxide hole collector, featuring a fill factor value higher than 80% and certified energy conversion efficiency of 22.5%.

  14. Method for enhancing the solubility of boron and indium in silicon

    DOEpatents

    Sadigh, Babak; Lenosky, Thomas J.; Diaz de la Rubia, Tomas; Giles, Martin; Caturla, Maria-Jose; Ozolins, Vidvuds; Asta, Mark; Theiss, Silva; Foad, Majeed; Quong, Andrew

    2002-01-01

    A method for enhancing the equilibrium solubility of boron and indium in silicon. The method involves first-principles quantum mechanical calculations to determine the temperature dependence of the equilibrium solubility of two important p-type dopants in silicon, namely boron and indium, under various strain conditions. The equilibrium thermodynamic solubility of size-mismatched impurities, such as boron and indium in silicon, can be raised significantly if the silicon substrate is strained appropriately. For example, for boron, a 1% compressive strain raises the equilibrium solubility by 100% at 1100.degree. C.; and for indium, a 1% tensile strain at 1100.degree. C., corresponds to an enhancement of the solubility by 200%.

  15. Discovering a Defect that Imposes a Limit to Mg Doping in p-TypeGaN

    SciTech Connect

    Liliental-Weber, Z.; Tomaszewicz, T.; Zakharov, D.; O'Keefe, M.A.

    2006-07-20

    Gallium nitride (GaN) is the III-V semiconductor used to produce blue light-emitting diodes (LEDs) and blue and ultraviolet solid-state lasers. To be useful in electronic devices, GaN must be doped with elements that function either as electron donors or as acceptors to turn it into either an n-type semiconductor or a p-type semiconductor. It has been found that GaN can easily be grown with n-conductivity, even up to large concentrations of donors--in the few 10{sup 19}cm{sup -3} range. However, p-doping, the doping of the structure with atoms that provide electron sinks or holes, is not well understood and remains extremely difficult. The only efficient p-type dopant is Mg, but it is found that the free hole concentration is limited to 2 x 10{sup 18}cm{sup -3}, even when Mg concentrations are pushed into the low 10{sup 19}cm{sup -3} range. This saturation effect could place a limit on further development of GaN based devices. Further increase of the Mg concentration, up to 1 x 10{sup 20}cm{sup -3} leads to a decrease of the free hole concentration and an increase in defects. While low- to medium-brightness GaN light-emitting diodes (LEDs) are remarkably tolerant of crystal defects, blue and UV GaN lasers are much less so. We used electron microscopy to investigate Mg doping in GaN. Our transmission electron microscopy (TEM) studies revealed the formation of different types of Mg-rich defects [1,2]. In particular, high-resolution TEM allowed us to characterize a completely new type of defect in Mg-rich GaN. We found that the type of defect depended strongly on crystal growth polarity. For crystals grown with N-polarity, planar defects are distributed at equal distances (20 unit cells of GaN); these defects can be described as inversion domains [1]. For growth with Ga-polarity, we found a different type of defect [2]. These defects turn out to be three-dimensional Mg-rich hexagonal pyramids (or trapezoids) with their base on the (0001) plane and their six walls

  16. Inkjet Printing NiO-Based p-Type Dye-Sensitized Solar Cells.

    PubMed

    Brisse, R; Faddoul, R; Bourgeteau, T; Tondelier, D; Leroy, J; Campidelli, S; Berthelot, T; Geffroy, B; Jousselme, B

    2017-01-25

    Fabrication at low cost of transparent p-type semiconductors with suitable electronic properties is essential toward the scalability of many electronic devices, especially for photovoltaic and photocatalytic applications. In this context, the synthesis of mesoporous NiO films through inkjet printing of a sol-gel ink was investigated for the first time. Nickel chloride and Pluronic F-127, used as nickel oxide precursor and pore-forming agent, respectively, were formulated in a water/ethanol mixture to prepare a jettable ink for Dimatix printer. Multilayer NiO films were formed, and different morphologies could be obtained by playing on the interlayer thermal treatment. At low temperature (30 °C), a porous nanoparticulate-nanofiber dual-pore structure was observed. On the other hand, with a high temperature treatment (450 °C), nanoparticulate denser films without any dual structure were obtained. The mechanism for NiO formation during the final sintering step, investigated by means of X-ray photolectron spectroscopy, shows that a Ni(OH)2 species is an intermediate between NiCl2 and NiO. The different morphologies and thicknesses of the NiO films were correlated to their performance in a p-DSSC configuration, using a new push-pull dye (so-called "RBG-174") and an iodine-based electrolyte. Moreover, the positive impact of a nanometric NiOx layer deposited by spin-coating and introduced between FTO and the NiO mesoporous network is highlighted in the present work. The best results were obtained with NiOx/four layer-NiO mesoporous photocathodes of 860 nm, with a current density at the short circuit of 3.42 mA cm(-2) (irradiance of 100 mW cm(-2) spectroscopically distributed following AM 1.5).

  17. PAA1, a P-Type ATPase of Arabidopsis, Functions in Copper Transport in Chloroplasts

    PubMed Central

    Shikanai, Toshiharu; Müller-Moulé, Patricia; Munekage, Yuri; Niyogi, Krishna K.; Pilon, Marinus

    2003-01-01

    Copper (Cu) is an essential trace element with important roles as a cofactor in many plant functions, including photosynthesis. However, free Cu ions can cause toxicity, necessitating precise Cu delivery systems. Relatively little is known about Cu transport in plant cells, and no components of the Cu transport machinery in chloroplasts have been identified previously. Cu transport into chloroplasts provides the cofactor for the stromal enzyme copper/zinc superoxide dismutase (Cu/ZnSOD) and for the thylakoid lumen protein plastocyanin, which functions in photosynthetic electron transport from the cytochrome b6f complex to photosystem I. Here, we characterized six Arabidopsis mutants that are defective in the PAA1 gene, which encodes a member of the metal-transporting P-type ATPase family with a functional N-terminal chloroplast transit peptide. paa1 mutants exhibited a high-chlorophyll-fluorescence phenotype as a result of an impairment of photosynthetic electron transport that could be ascribed to decreased levels of holoplastocyanin. The paa1-1 mutant had a lower chloroplast Cu content, despite having wild-type levels in leaves. The electron transport defect of paa1 mutants was evident on medium containing <1 μM Cu, but it was suppressed by the addition of 10 μM Cu. Chloroplastic Cu/ZnSOD activity also was reduced in paa1 mutants, suggesting that PAA1 mediates Cu transfer across the plastid envelope. Thus, PAA1 is a critical component of a Cu transport system in chloroplasts responsible for cofactor delivery to plastocyanin and Cu/ZnSOD. PMID:12782727

  18. Distribution of iron in multicrystalline silicon ingots

    NASA Astrophysics Data System (ADS)

    Kvande, R.; Geerligs, L. J.; Coletti, G.; Arnberg, L.; Di Sabatino, M.; Øvrelid, E. J.; Swanson, C. C.

    2008-09-01

    The distribution of iron in multicrystalline silicon ingots for solar cells has been studied. A p- and a n-type multicrystalline ingot were intentionally contaminated by adding 53ppmwt (μg/g) of iron to the silicon feedstock and compared to a reference p-type ingot produced from ultrapure silicon feedstock. The vertical total iron distribution was determined by neutron activation analysis and glow discharge mass spectrometry. For the intentionally Fe-contaminated ingots, the distribution can be described by Scheil's equation with an effective distribution coefficient of 2×10-5. The interstitial iron concentration was measured in the p-type ingots. In the Fe-contaminated ingot, it is almost constant throughout the ingot and constitutes about 50% of the total concentration, which is in conflict with the previous studies. Gettering had a large impact on the interstitial iron levels by reducing the concentration by two orders of magnitude. Considerable trapping was observed at crystal defects on as-cut wafers from the same ingot. The trapping was suppressed by gettering. The back diffusion of iron from the ingot top after complete solidification was modeled and found to affect the iron concentration up to a distance of approximately 17mm into the ingot. The interstitial as well as the total iron concentration of the reference ingot were extremely low and difficult to measure accurately.

  19. Growth and conduction mechanism of As-doped p-type ZnO thin films deposited by MOCVD

    SciTech Connect

    Ma, Y.; Gao, Q.; Wu, G.G.; Li, W.C.; Gao, F.B.; Yin, J.Z.; Zhang, B.L.; Du, G.T.

    2013-03-15

    Highlight: ► P-type As-doped ZnO thin films was fabricated by MOCVD after post-growth annealing. ► The formation mechanism of p-ZnO with high hole concentration above 10{sup 19} cm{sup −3} was elucidated. ► Besides As{sub Zn}–2V{sub Zn} complex, C impurities also played an important role in realizing p-ZnO. ► The formations of As{sub O} and O-C-O complex were partially contributed to the p-type ZnO: As films. - Abstract: As-doped p-type ZnO thin films were fabricated by metal organic chemical vapor deposition (MOCVD) after in situ annealing in a vacuum. The p-type conduction mechanism was suggested by the analysis of X-ray photoelectron spectroscopy and ultraviolet photoemission spectroscopy. It was found that most of the As dopants in p-ZnO thin films formed As{sub Zn}–2V{sub Zn} shallow acceptor complex, simultaneously, carbon impurities also played an important role in realizing p-type conductivity in ZnO. Substitutional carbon on oxygen site created passivated defect bands by combining with Ga atoms due to the donor-acceptor pair Coulomb binding, which shifted the valence-band maximum upwards for ZnO and thus increased the hole concentration.

  20. Photoluminescence study of p-type vs. n-type Ag-doped ZnO films

    SciTech Connect

    Myers, M. A.; Jian, J.; Khranovskyy, V.; Lee, J. H.; Wang, Han; Wang, Haiyan E-mail: hwang00@tamu.edu

    2015-08-14

    Silver doped ZnO films have been grown on sapphire (0001) substrates by pulsed laser deposition. Hall measurements indicate that p-type conductivity is realized for the films deposited at 500 °C and 750 °C. Transmission electron microscopy images show more obvious and higher density of stacking faults (SFs) present in the p-type ZnO films as compared to the n-type films. Top view and cross sectional photoluminescence of the n- and p-type samples revealed free excitonic emission from both films. A peak at 3.314 eV, attributed to SF emission, has been observed only for the n-type sample, while a weak neutral acceptor peak observed at 3.359 eV in the p-type film. The SF emission in the n-type sample suggests localization of acceptor impurities nearby the SFs, while lack of SF emission for the p-type sample indicates the activation of the Ag acceptors in ZnO.

  1. Silicon concentrator solar cell research

    SciTech Connect

    Green, M.A.; Zhao, J.; Wang, A.; Dai, X.; Milne, A.; Cai, S.; Aberle, A.; Wenham, S.R.

    1993-06-01

    This report describes work conducted between December 1990 and May 1992 continuing research on silicon concentrator solar cells. The objectives of the work were to improve the performance of high-efficiency cells upon p-type substrates, to investigate the ultraviolet stability of such cells, to develop concentrator cells based on n-type substrates, and to transfer technology to appropriate commercial environments. Key results include the identification of contact resistance between boron-defused areas and rear aluminum as the source of anomalously large series resistance in both p- and n-type cells. A major achievement of the present project was the successful transfer of cell technology to both Applied Solar Energy Corporation and Solarex Corporation.

  2. Fabrication of p-type ZnO nanofibers by electrospinning for field-effect and rectifying devices

    SciTech Connect

    Liu, Shuai; Liu, Shu-Liang; Liu, Ling-Zhi; Liu, Yi-Chen; Long, Yun-Ze; Zhang, Hong-Di; Zhang, Jun-Cheng; Han, Wen-Peng

    2014-01-27

    Ce-doped p-type ZnO nanofibers were synthesized by electrospinning and followed calcinations. The surface morphology, elementary composition, and crystal structure of the nanofibers were investigated. The field effect curve confirms that the resultant Ce-doped ZnO nanofibers are p-type semiconductor. A p-n heterojunction device consisting of Ce-doped p-type ZnO nanofibers and n-type indium tin oxide (ITO) thin film was fabricated on a piece of quartz substrate. The current-voltage (I-V) characteristic of the p-n heterojunction device shows typical rectifying diode behavior. The turn-on voltage appears at about 7 V under the forward bias and the reverse current is impassable.

  3. Modeling of normal incidence absorption in p-type GaAs/AlGaAs quantum well infrared detectors

    NASA Astrophysics Data System (ADS)

    Brown, Gail J.; Szmulowicz, Frank

    1995-04-01

    The absorption of infrared radiation at normal incidence in p-type GaAs/AlGaAs quantum wells, unlike in n-type, is fundamentally allowed. We have measured and theoretically modeled the bound-to-continuum absorption in these p-type materials. The infrared absorption coefficient was calculated are based on the electronic structure, wave functions and optical matrix elements obtained from an 8 X 8 envelope-function approximation (EFA) calculation. The 8 X 8 EFA Hamiltonian incorporates the coupling between the heavy, light, spin-orbit, and conduction bands. In calculating the continuum states for bound-to- continuum intersubband absorption, we do not enclose the well in an artificial box with infinite walls. A comparison of the theoretical absorption and measured photoresponse results verified the accuracy of our model and provided a basis for optimizing the design of p-type quantum wells for infrared detection.

  4. Optical and electronic transport properties of p-type CuCoO2 transparent conductive oxide

    NASA Astrophysics Data System (ADS)

    Ruttanapun, Chesta; Sa-nguan-cheep, Minraya; Kahatta, Sagulthai; Buranasiri, Prathan; Jindajitawat, Phumin

    2013-06-01

    The CuCoO2 sample has been synthesized by a conventional solid-state reaction method to investigate electronic transport and optical properties for p-type transparent conducting oxide materials. The crystal structure was characterized by XRD. The Seebeck coefficient and electrical conductivity were measured in the high temperature. The UV-VIS-NIR and FTIR spectra were analyzed at room temperature. The XRD peaks confirm the samples forming the delafossite structure phase. The Seebeck coefficient sign confirms the samples displays the p-type conducting. The electronic transport energy for activating free carrier production and conduction contain 0.276 eV and 0.131 eV, respectively. The optical direct gap is 3.65 eV which is a visible-transparent oxide material. These results support that the CuCoO2 oxide compound is p-type transparent conducting oxide materials.

  5. Computational prediction of high thermoelectric performance in p-type half-Heusler compounds with low band effective mass.

    PubMed

    Fang, Teng; Zheng, Shuqi; Zhou, Tian; Yan, Lei; Zhang, Peng

    2017-02-08

    Half-Heusler (HH) compounds are important high temperature thermoelectric (TE) materials and have gained ever-increasing popularity. In recent years, p-type FeNbSb-based heavy-band HH compounds have attracted considerable attention with the record-high zT value of 1.5. Here, we use first-principles based methods to predict a very high zT value of 1.54 at 1200 K in p-type RuTaSb alloys. The high band degeneracy and low band effective mass contribute to a high power factor. Although the electrical thermal conductivity is high due to the high carrier mobility and hence electrical conductivity, the total thermal conductivity is moderate because of the low lattice thermal conductivity. The predicted high zT demonstrates that the p-type RuTaSb HH alloys are promising as TE materials for high temperature power generation.

  6. Boric acid solution concentration influencing p-type emitter formation in n-type crystalline Si solar cells

    NASA Astrophysics Data System (ADS)

    Singha, Bandana; Singh Solanki, Chetan

    2016-09-01

    Boric acid (BA) is a spin on dopant (BSoD) source which is used to form p+ emitters in n-type c-Si solar cells. High purity boric acid powder (99.99% pure) when mixed with deionized (DI) water can result in high quality p-type emitter with less amount of surface defects. In this work, we have used different concentrations of boric acid solution concentrations to fabricate p-type emitters with sheet resistance values < 90 Ω/□. The corresponding junction depths for the same are less than 500 nm as measured by SIMS analysis. Boron rich layer (BRL), which is considered as detrimental in emitter performance is found to be minimal for BA solution concentration less than 2% and hence useful for p-type emitter formation.

  7. Silicon Detectors

    NASA Astrophysics Data System (ADS)

    Sadrozinski, Hartmut

    2014-03-01

    The use of silicon detectors has experienced an exponential growth in accelerator and space based experiments, similar to trends in the semiconductor industry as a whole, usually paraphrased as ``Moore's Law.'' Some of the essentials for this phenomenon will be presented, together with examples of the exciting science results which it enabled. With the establishment of a ``semiconductor culture'' in universities and laboratories around the world, an increased understanding of the sensors results in thinner, faster, more radiation-resistant detectors, spawning an amazing wealth of new technologies and applications, which will be the main subject of the presentation.

  8. A case of mimicking angioedema: chin silicone granulomatous reaction spreading all over the face after receiving liquid silicone injection forty years previously.

    PubMed

    Chen, Yu-Cheng; Chen, Mei-Ling; Chiu, Ying-Ming

    2011-06-01

    Liquid injectable silicone has been used for soft tissue augmentation for five decades. Many complications following liquid silicone injection have been reported. To diagnose and manage silicone granuloma remains difficult. Silicone granuloma must be diagnosed with the history of liquid silicone injection and the histology of tissue biopsy. We presented a case of granulomatous reaction after the injection of liquid silicone for chin augmentation forty years ago, causing total facial swelling, which mimicking angioedema initially. We administered methylprednisolone to the patient. Initial response to methylprednisolone was favorable.

  9. Weak-Localization in n- and p-TYPE Films of Pb1-xEuxTe

    NASA Astrophysics Data System (ADS)

    Peres, M. L.; Chitta, V. A.; Gusev, G. M.; Oliveira, Nei F.; Rappl, P. H. O.; Ueta, A. Y.; Abramof, E.

    We investigated the magnetotransport properties of n- and p-type films of Pb1-xEuxTe grown by molecular beam epitaxy, with Eu concentrations close to the Metal-Insulator transition. The n-type sample shows a negative magnetoresistance which magnitude increases continually as the temperature is lowered. On the other hand, for the p-type sample, a negative magnetoresistance can be observed only for temperatures below 7 K. Comparing the magnetoresistance of both samples we show that the scattering mechanism should have a different origin.

  10. Porous silicon-based biosensor for pathogen detection.

    PubMed

    Mathew, Finny P; Alocilja, Evangelyn C

    2005-02-15

    A porous silicon-based biosensor for rapid detection of bacteria was fabricated. Silicon (0.01 ohmcm, p-type) was anodized electrochemically in an electrochemical Teflon cell containing ethanoic hydrofluoric acid solution to produce sponge-like porous layer of silicon. Anodizing conditions of 5 mA/cm2 for 85 min proved best for biosensor fabrication. A single-tube chemiluminescence-based assay, previously developed, was adapted to the biosensor for detection of Escherichia coli. Porous silicon chips were functionalized with a dioxetane-Polymyxin B (cell wall permeabilizer) mixture by diffusion and adsorption on to the porous surface. The reaction of beta-galactosidase enzyme from E. coli with the dioxetane substrate generated light at 530 nm. Light emission for the porous silicon biosensor chip with E. coli was significantly greater than that of the control and planar silicon chip with E. coli (P<0.01). Sensitivity of the porous silicon biosensor was determined to be 101-102 colony forming units (CFU) of E. coli. The porous silicon-based biosensor was fabricated and functionalized to successfully detect E. coli and has potential applications in food and environmental testing.

  11. Studies on the reactive melt infiltration of silicon and silicon-molybdenum alloys in porous carbon

    NASA Technical Reports Server (NTRS)

    Singh, M.; Behrendt, D. R.

    1992-01-01

    Investigations on the reactive melt infiltration of silicon and silicon-1.7 and 3.2 at percent molybdenum alloys into porous carbon preforms have been carried out by process modeling, differential thermal analysis (DTA) and melt infiltration experiments. These results indicate that the initial pore volume fraction of the porous carbon preform is a critical parameter in determining the final composition of the raction-formed silicon carbide and other residual phases. The pore size of the carbon preform is very detrimental to the exotherm temperatures due to liquid silicon-carbon reactions encountered during the reactive melt infiltration process. A possible mechanism for the liquid silicon-porous (glassy) carbon reaction has been proposed. The composition and microstructure of the reaction-formed silicon carbide has been discussed in terms of carbon preform microstructures, infiltration materials, and temperatures.

  12. Wetting and infiltration of nitride bonded silicon nitride by liquid silicon

    NASA Astrophysics Data System (ADS)

    Schneider, V.; Reimann, C.; Friedrich, J.

    2016-04-01

    Nitride bonded silicon nitride (NBSN) is a promising crucible material for the repeated use in the directional solidification of multicrystalline (mc) silicon ingots for photovoltaic applications. Due to wetting and infiltration, however, silicon nitride in its initial state does not offer the desired reusability. In this work the sessile drop method is used to systematically study the wetting and infiltration behavior of NBSN after applying different oxidation procedures. It is found that the wetting of the NBSN crucible by liquid silicon can be prevented by the oxidation of the geometrical surface. The infiltration of liquid silicon into the porous crucible can be suppressed by oxygen enrichment within the volume of the NBSN, i.e. at the pore walls of the crucibles. The realized reusability of the NBSN is demonstrated by reusing a NBSN crucible six times for the directional solidification of undoped multicrystalline silicon ingots.

  13. Patterned growth of p-type MoS2 atomic layers using sol-gel as precursor

    DOE PAGES

    Zheng, Wei; Lin, Junhao; Feng, Wei; ...

    2016-07-19

    2D layered MoS2 has drawn intense attention for its applications in flexible electronic, optoelectronic, and spintronic devices. Most of the MoS2 atomic layers grown by conventional chemical vapor deposition techniques are n-type due to the abundant sulfur vacancies. Facile production of MoS2 atomic layers with p-type behavior, however, remains challenging. Here, a novel one-step growth has been developed to attain p-type MoS2 layers in large scale by using Mo-containing sol–gel, including 1% tungsten (W). Atomic-resolution electron microscopy characterization reveals that small tungsten oxide clusters are commonly present on the as-grown MoS2 film due to the incomplete reduction of W precursormore » at the reaction temperature. These omnipresent small tungsten oxide clusters contribute to the p-type behavior, as verified by density functional theory calculations, while preserving the crystallinity of the MoS2 atomic layers. The Mo containing sol–gel precursor is compatible with the soft-lithography techniques, which enables patterned growth of p-type MoS2 atomic layers into regular arrays with different shapes, holding great promise for highly integrated device applications. Lastly, an atomically thin p–n junction is fabricated by the as-prepared MoS2, which shows strong rectifying behavior.« less

  14. Study of p-type ZnO and MgZnO Thin Films for Solid State Lighting

    SciTech Connect

    Liu, Jianlin

    2015-07-31

    This project on study of p-type ZnO and MgZnO thin films for solid state lighting was carried out by research group of Prof. Jianlin Liu of UCR during the four-year period between August 2011 and July 2015. Tremendous progress has been made on the proposed research. This final report summarizes the important findings.

  15. Identification and molecular characterization of a novel DyP-type peroxidase from Pseudomonas aeruginosa PKE117.

    PubMed

    Li, Jing; Liu, Chen; Li, Baozhen; Yuan, Hongli; Yang, Jinshui; Zheng, Beiwen

    2012-02-01

    A new DyP-type peroxidase from Pseudomonas aeruginosa PKE117 was identified and characterized. The dypPa was first identified via sequence analysis and then cloned in Escherichia coli. Subsequently, the recombinant protein DyPPa was expressed and purified. Its DNA sequence analysis revealed an open reading frame of 897 bp, encoding a protein monomer of 299 amino acid residues with isoelectric point 4.62. According to SDS-PAGE analysis and FPLC result, DyPPa mainly existed as homodimer (64 kDa). DyPPa displayed typical heme absorbance of Soret band, with an Rz value of 1.18. Inductively coupled plasma-atomic absorption spectrum data also indicated DyPPa contained iron. Multiple amino acid sequence alignment of DyPPa with other members of the DyP-type peroxidases family showed the presence of conserved D139, H210, and R227 amino acids and GXXDG motifs, which were commonly shared by the DyP-type peroxidase family. Although the primary structure homology between DyPPa and other family members was very low, their secondary and tertiary structure displayed high homology, which explained the high decolorizing activity of DyPPa. Specifically, DyPPa displayed a good thermal stability and maximal activity on Reactive blue 5 under pH 3.5. Therefore, it was proposed that DyPPa, with a wide range of substrate specificity, was a novel member of the DyP-type peroxidases family.

  16. Native defect properties and p -type doping efficiency in group-IIA doped wurtzite AlN

    NASA Astrophysics Data System (ADS)

    Zhang, Yong; Liu, Wen; Niu, Hanben

    2008-01-01

    Using the first-principles full-potential linearized augmented plane-wave (FPLAPW) method based on density functional theory (DFT), we have investigated the native defect properties and p -type doping efficiency in AlN doped with group-IIA elements such as Be, Mg, and Ca. It is shown that nitrogen vacancies (VN) have low formation energies and introduce deep donor levels in wurtzite AlN, while in zinc blende AlN and GaN, these levels are reported to be shallow. The calculated acceptor levels γ(0/-) for substitutional Be (BeAl) , Mg (MgAl) , and Ca (CaAl) are 0.48, 0.58, and 0.95eV , respectively. In p -type AlN, Be interstitials (Bei) , which act as donors, have low formation energies, making them a likely compensating center in the case of acceptor doping. Whereas, when N-rich growth conditions are applied, Bei are energetically not favorable. It is found that p -type doping efficiency of substitutional Be, Mg, and Ca impurities in w-AlN is affected by atomic size and electronegativity of dopants. Among the three dopants, Be may be the best candidate for p -type w-AlN . N-rich growth conditions help us to increase the concentration of BeAl , MgAl , and CaAl .

  17. Patterned growth of p-type MoS2 atomic layers using sol-gel as precursor

    SciTech Connect

    Zheng, Wei; Lin, Junhao; Feng, Wei; Xiao, Kai; Qiu, Yunfeng; Chen, XiaoShuang; Liu, Guangbo; Cao, Wenwu; Pantelides, Sokrates T.; Zhou, Wu; Hu, PingAn

    2016-07-19

    2D layered MoS2 has drawn intense attention for its applications in flexible electronic, optoelectronic, and spintronic devices. Most of the MoS2 atomic layers grown by conventional chemical vapor deposition techniques are n-type due to the abundant sulfur vacancies. Facile production of MoS2 atomic layers with p-type behavior, however, remains challenging. Here, a novel one-step growth has been developed to attain p-type MoS2 layers in large scale by using Mo-containing sol–gel, including 1% tungsten (W). Atomic-resolution electron microscopy characterization reveals that small tungsten oxide clusters are commonly present on the as-grown MoS2 film due to the incomplete reduction of W precursor at the reaction temperature. These omnipresent small tungsten oxide clusters contribute to the p-type behavior, as verified by density functional theory calculations, while preserving the crystallinity of the MoS2 atomic layers. The Mo containing sol–gel precursor is compatible with the soft-lithography techniques, which enables patterned growth of p-type MoS2 atomic layers into regular arrays with different shapes, holding great promise for highly integrated device applications. Lastly, an atomically thin p–n junction is fabricated by the as-prepared MoS2, which shows strong rectifying behavior.

  18. Optical and electronic properties of delafossite CuBO{sub 2}p-type transparent conducting oxide

    SciTech Connect

    Ruttanapun, Chesta E-mail: krchesta@kmitl.ac.th

    2013-09-21

    CuBO{sub 2} delafossite was prepared by solid state reaction and calcined/sintered at 1005 °C. The optical properties of this p-type transparent conducting oxide were investigated. Its crystal structure, morphology, composition, oxygen decomposition, and optical and electronic properties were characterized by X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy, thermal gravimetric analysis (TGA), ultraviolet-visible-near-infrared (UV-VIS-NIR) and fluorescence spectroscopies, Seebeck coefficient, and electrical conductivity measurements. CuBO{sub 2} delafossite possesses a hexagonal space group R3{sup ¯}m. TGA indicated a weight loss of 10%, which was attributed to excess oxygen. The positive Seebeck coefficient confirmed p-type behavior. Emission at 355 nm indicated a direct band type transition, and the UV-VIS-NIR spectrum indicated an optical direct gap of 3.6 eV. Activation energies for carrier production and electrical conduction were 0.147 and 0.58 eV, respectively, indicating the thermal activation of carriers. CuBO{sub 2} delafossite is a p-type transparent conducting oxide with a wide band gap and may have potential in industrial p-type electrodes.

  19. In silico approaches and chemical space of anti-P-type ATPase compounds for discovering new antituberculous drugs.

    PubMed

    Santos, Paola; López-Vallejo, Fabian; Soto, Carlos-Y

    2017-01-22

    Tuberculosis (TB) is one of the most important public health problems around the world. The emergence of multi-drug-resistant (MDR) and extensively drug-resistant (XDR) Mycobacterium tuberculosis strains has driven the finding of alternative anti-TB targets. In this context, P-type ATPases are interesting therapeutic targets due to their key role in ion homeostasis across the plasma membrane and the mycobacterial survival inside macrophages. In this review, in silico and experimental strategies used for the rational design of new anti-TB drugs are presented; in addition, the chemical space distribution based on the structure and molecular properties of compounds with anti-TB and anti-P-type ATPase activity is discussed. The chemical space distribution compared to public compound libraries demonstrates that natural product libraries are a source of novel chemical scaffolds with potential anti-P-type ATPase activity. Furthermore, compounds that experimentally display anti-P-type ATPase activity belong to a chemical space of molecular properties comparable to that occupied by those approved for oral use, suggesting that these kinds of molecules have a good pharmacokinetic profile (drug-like) for evaluation as potential anti-TB drugs.

  20. A CMOS silicon spin qubit

    NASA Astrophysics Data System (ADS)

    Maurand, R.; Jehl, X.; Kotekar-Patil, D.; Corna, A.; Bohuslavskyi, H.; Laviéville, R.; Hutin, L.; Barraud, S.; Vinet, M.; Sanquer, M.; de Franceschi, S.

    2016-11-01

    Silicon, the main constituent of microprocessor chips, is emerging as a promising material for the realization of future quantum processors. Leveraging its well-established complementary metal-oxide-semiconductor (CMOS) technology would be a clear asset to the development of scalable quantum computing architectures and to their co-integration with classical control hardware. Here we report a silicon quantum bit (qubit) device made with an industry-standard fabrication process. The device consists of a two-gate, p-type transistor with an undoped channel. At low temperature, the first gate defines a quantum dot encoding a hole spin qubit, the second one a quantum dot used for the qubit read-out. All electrical, two-axis control of the spin qubit is achieved by applying a phase-tunable microwave modulation to the first gate. The demonstrated qubit functionality in a basic transistor-like device constitutes a promising step towards the elaboration of scalable spin qubit geometries in a readily exploitable CMOS platform.

  1. A CMOS silicon spin qubit

    PubMed Central

    Maurand, R.; Jehl, X.; Kotekar-Patil, D.; Corna, A.; Bohuslavskyi, H.; Laviéville, R.; Hutin, L.; Barraud, S.; Vinet, M.; Sanquer, M.; De Franceschi, S.

    2016-01-01

    Silicon, the main constituent of microprocessor chips, is emerging as a promising material for the realization of future quantum processors. Leveraging its well-established complementary metal–oxide–semiconductor (CMOS) technology would be a clear asset to the development of scalable quantum computing architectures and to their co-integration with classical control hardware. Here we report a silicon quantum bit (qubit) device made with an industry-standard fabrication process. The device consists of a two-gate, p-type transistor with an undoped channel. At low temperature, the first gate defines a quantum dot encoding a hole spin qubit, the second one a quantum dot used for the qubit read-out. All electrical, two-axis control of the spin qubit is achieved by applying a phase-tunable microwave modulation to the first gate. The demonstrated qubit functionality in a basic transistor-like device constitutes a promising step towards the elaboration of scalable spin qubit geometries in a readily exploitable CMOS platform. PMID:27882926

  2. A CMOS silicon spin qubit.

    PubMed

    Maurand, R; Jehl, X; Kotekar-Patil, D; Corna, A; Bohuslavskyi, H; Laviéville, R; Hutin, L; Barraud, S; Vinet, M; Sanquer, M; De Franceschi, S

    2016-11-24

    Silicon, the main constituent of microprocessor chips, is emerging as a promising material for the realization of future quantum processors. Leveraging its well-established complementary metal-oxide-semiconductor (CMOS) technology would be a clear asset to the development of scalable quantum computing architectures and to their co-integration with classical control hardware. Here we report a silicon quantum bit (qubit) device made with an industry-standard fabrication process. The device consists of a two-gate, p-type transistor with an undoped channel. At low temperature, the first gate defines a quantum dot encoding a hole spin qubit, the second one a quantum dot used for the qubit read-out. All electrical, two-axis control of the spin qubit is achieved by applying a phase-tunable microwave modulation to the first gate. The demonstrated qubit functionality in a basic transistor-like device constitutes a promising step towards the elaboration of scalable spin qubit geometries in a readily exploitable CMOS platform.

  3. Heavy doping effects in high efficiency silicon solar cells

    NASA Technical Reports Server (NTRS)

    Lindholm, F. A.; Neugroschel, A.; Landsberg, P. T.; San, C. T.

    1984-01-01

    A model for bandgap shrinkage in semiconductors is developed and applied to silicon. A survey of earlier experiments, and of new ones, give an agreement between the model and experiments on n- and p-type silicon which is good as far as transport measurements in the 300 K range. The discrepancies between theory and experiment are no worse than the discrepancies between the experimental results of various authors. It also gives a good account of recent, optical determinations of band gap shrinkage at 5 K.

  4. Gadolinium Oxide / Silicon Thin Film Heterojunction Solid-State Neutron Detector

    DTIC Science & Technology

    2010-03-01

    gadolinium oxide (Gd2O3) and p-type silicon heterojunction diodes were produced using a supercritical water deposition process . Pulse height spectroscopy...possible to produce semi-conductor devices that have a high probability of neutron interaction. 1.2 Problem Statement Can a heterojunction diode...materials. The second area develops a method of depositing Gd on silicon with subsequent device fabrication. The third is a feasibility study that

  5. S-type and P-type Habitability in Stellar Binary Systems: A Comprehensive Approach. I. Method and Applications

    NASA Astrophysics Data System (ADS)

    Cuntz, M.

    2014-01-01

    A comprehensive approach is provided for the study of both S-type and P-type habitability in stellar binary systems, which in principle can also be expanded to systems of higher order. P-type orbits occur when the planet orbits both binary components, whereas in the case of S-type orbits, the planet orbits only one of the binary components with the second component considered a perturbator. The selected approach encapsulates a variety of different aspects, which include: (1) the consideration of a joint constraint, including orbital stability and a habitable region for a putative system planet through the stellar radiative energy fluxes ("radiative habitable zone"; RHZ), needs to be met; (2) the treatment of conservative, general, and extended zones of habitability for the various systems as defined for the solar system and beyond; (3) the provision of a combined formalism for the assessment of both S-type and P-type habitability; in particular, mathematical criteria are presented for the kind of system in which S-type and P-type habitability is realized; (4) applications of the attained theoretical approach to standard (theoretical) main-sequence stars. In principle, five different cases of habitability are identified, which are S-type and P-type habitability provided by the full extent of the RHZs; habitability, where the RHZs are truncated by the additional constraint of planetary orbital stability (referred to as ST- and PT-type, respectively); and cases of no habitability at all. Regarding the treatment of planetary orbital stability, we utilize the formulae of Holman & Wiegert as also used in previous studies. In this work, we focus on binary systems in circular orbits. Future applications will also consider binary systems in elliptical orbits and provide thorough comparisons to other methods and results given in the literature.

  6. S-type and P-type habitability in stellar binary systems: A comprehensive approach. I. Method and applications

    SciTech Connect

    Cuntz, M.

    2014-01-01

    A comprehensive approach is provided for the study of both S-type and P-type habitability in stellar binary systems, which in principle can also be expanded to systems of higher order. P-type orbits occur when the planet orbits both binary components, whereas in the case of S-type orbits, the planet orbits only one of the binary components with the second component considered a perturbator. The selected approach encapsulates a variety of different aspects, which include: (1) the consideration of a joint constraint, including orbital stability and a habitable region for a putative system planet through the stellar radiative energy fluxes ({sup r}adiative habitable zone{sup ;} RHZ), needs to be met; (2) the treatment of conservative, general, and extended zones of habitability for the various systems as defined for the solar system and beyond; (3) the provision of a combined formalism for the assessment of both S-type and P-type habitability; in particular, mathematical criteria are presented for the kind of system in which S-type and P-type habitability is realized; (4) applications of the attained theoretical approach to standard (theoretical) main-sequence stars. In principle, five different cases of habitability are identified, which are S-type and P-type habitability provided by the full extent of the RHZs; habitability, where the RHZs are truncated by the additional constraint of planetary orbital stability (referred to as ST- and PT-type, respectively); and cases of no habitability at all. Regarding the treatment of planetary orbital stability, we utilize the formulae of Holman and Wiegert as also used in previous studies. In this work, we focus on binary systems in circular orbits. Future applications will also consider binary systems in elliptical orbits and provide thorough comparisons to other methods and results given in the literature.

  7. Silicon carbide

    SciTech Connect

    Ault, N.N.; Crowe, J.T. )

    1991-05-01

    This paper reports that, since silicon carbide (SiC) does not occur in nature, it must be synthesized by a high-temperature chemical reaction. The first commercial production began at the end of the 19th century when Acheson developed a process of reacting sand and coke in a resistance furnace. This process is still the basic SiC manufacturing process used today. High-quality silica sand (99.5% SiO{sub 2}), low-sulfur petroleum coke, and electricity (23.8 MJ/kg) are the major ingredients in the production of SiC. The reaction takes place in a trough-like furnace with a removable refractory side (or some similar configuration) and with permanent refractory ends holding carbon electrodes. When the furnace is started, the carbon electrodes are joined by the graphite core laid the length of the furnace near the center of the mixture which fills the furnace.

  8. Porous silicon carbide (SiC) semiconductor device

    NASA Technical Reports Server (NTRS)

    Shor, Joseph S. (Inventor); Kurtz, Anthony D. (Inventor)

    1994-01-01

    A semiconductor device employs at least one layer of semiconducting porous silicon carbide (SiC). The porous SiC layer has a monocrystalline structure wherein the pore sizes, shapes, and spacing are determined by the processing conditions. In one embodiment, the semiconductor device is a p-n junction diode in which a layer of n-type SiC is positioned on a p-type layer of SiC, with the p-type layer positioned on a layer of silicon dioxide. Because of the UV luminescent properties of the semiconducting porous SiC layer, it may also be utilized for other devices such as LEDs and optoelectronic devices.

  9. Thin silicon solar cells

    SciTech Connect

    Hall, R.B.; Bacon, C.; DiReda, V.; Ford, D.H.; Ingram, A.E.; Cotter, J.; Hughes-Lampros, T.; Rand, J.A.; Ruffins, T.R.; Barnett, A.M.

    1992-12-01

    The silicon-film design achieves high performance by using a dun silicon layer and incorporating light trapping. Optimally designed thin crystalline solar cells (<50 microns thick) have performance advantages over conventional thick devices. The high-performance silicon-film design employs a metallurgical barrier between the low-cost substrate and the thin silicon layer. Light trapping properties of silicon-film on ceramic solar cells are presented and analyzed. Recent advances in process development are described here.

  10. Stimulated Raman scattering from free holes in p-type indium antimonide

    NASA Astrophysics Data System (ADS)

    Ebert, R.; Pascher, H.; Häfele, H. G.

    1981-06-01

    Stimulated Raman scattering from photoexcited holes at magnetic fields up to 68 kG in p-InSb is described. Experiments varying excitation wavelength, magnetic field, polarization, and sample orientation are discussed. A comparison of the experimental results with the latest valence-band calculations allows the identification of the energy levels involved in the scattering process. For sample orientation H-->∥<100>, the initial state is the valence-band Landau level ALH 101+31 and the final state is BHH 313-31. ALH, BLH are the "light hole" ladders (approximate spin M=+32 and M=-32, respectively). AHH, BHH are the "heavy hole" ladders (approximate spin M=-12 and M=+12, respectively). For the orientation H-->∥<111> initial state and final state are BLH 000+ and AHH 32O+, respectively. The holes involved in this Raman scattering process always have a nonzero momentum along the direction of the magnetic field (kH≠0). The largest Raman shift we measured was about 2.7 cm-1.

  11. Silicon production in a fluidized bed reactor

    NASA Technical Reports Server (NTRS)

    Rohatgi, N. K.

    1986-01-01

    Part of the development effort of the JPL in-house technology involved in the Flat-Plate Solar Array (FSA) Project was the investigation of a low-cost process to produce semiconductor-grade silicon for terrestrial photovoltaic cell applications. The process selected was based on pyrolysis of silane in a fluidized-bed reactor (FBR). Following initial investigations involving 1- and 2-in. diameter reactors, a 6-in. diameter, engineering-scale FBR was constructed to establish reactor performance, mechanism of silicon deposition, product morphology, and product purity. The overall mass balance for all experiments indicates that more than 90% of the total silicon fed into the reactor is deposited on silicon seed particles and the remaining 10% becomes elutriated fines. Silicon production rates were demonstrated of 1.5 kg/h at 30% silane concentration and 3.5 kg/h at 80% silane concentration. The mechanism of silicon deposition is described by a six-path process: heterogeneous deposition, homogeneous decomposition, coalescence, coagulation, scavenging, and heterogeneous growth on fines. The bulk of the growth silicon layer appears to be made up of small diameter particles. This product morphology lends support to the concept of the scavenging of homogeneously nucleated silicon.

  12. Buried oxide layer in silicon

    DOEpatents

    Sadana, Devendra Kumar; Holland, Orin Wayne

    2001-01-01

    A process for forming Silicon-On-Insulator is described incorporating the steps of ion implantation of oxygen into a silicon substrate at elevated temperature, ion implanting oxygen at a temperature below 200.degree. C. at a lower dose to form an amorphous silicon layer, and annealing steps to form a mixture of defective single crystal silicon and polycrystalline silicon or polycrystalline silicon alone and then silicon oxide from the amorphous silicon layer to form a continuous silicon oxide layer below the surface of the silicon substrate to provide an isolated superficial layer of silicon. The invention overcomes the problem of buried isolated islands of silicon oxide forming a discontinuous buried oxide layer.

  13. Increasing the Deposition Rate of Silicon

    NASA Technical Reports Server (NTRS)

    Lutwack, R.; Yamakawa, K. A.

    1986-01-01

    Modified Siemens reactor enables chemical vapor deposition (CVD) of silicon to occur simultaneously on inner and outer surfaces of hollow cylinder, resulting in increase in mass of silicon deposited per unit time. Outer reactor for silicon deposition made from quartz or stainless steel. Hollow cylinder either single resistance-heated hollow cylinder about 5 to 10 cm or greater in diameter or 1-cm-diameter rods aligned in circular channels at top and bottom, initial circles being 5 to 10 cm in diameter or greater.

  14. On-line DLTS investigations of the mono- and di-vacancy in p-type silicon after low temperature electron irradiation

    NASA Astrophysics Data System (ADS)

    Zangenberg, Nikolaj; Goubet, Jean-Jacques; Nylandsted Larsen, Arne

    2002-01-01

    Using deep level transient spectroscopy (DLTS) and Laplace-DLTS, we have investigated vacancy-related defects created in boron-doped epitaxial Si by 2 MeV electron irradiations at low temperatures (⩽ 40 K) . The vacancy level is found at E v+0.12 eV together with a DLTS peak at E v+0.20 eV which anneals at ˜140 K and is tentatively identified as a vacancy in a different configuration. The emission rate of the dominant vacancy-related deep level in the temperature range from 200 to 550 K, namely the (0/+) transition of the di-vacancy (V 2), displays a very large dependence of the emission rate on the electric field strength in the depletion region of the diodes. This dependence is unexpected in terms of the classical Poole-Frenkel effect, given the neutral charge state of V 2 before hole capture. The effect of high fields appears to be caused by phonon assisted tunneling. When V anneals around 200 K, a new complex assigned to a vacancy-boron pair gives rise to two charge states. Quenching experiments with reverse bias show that the complex is bistable. It anneals at 260 K.

  15. Measurement and Theory of the Hall Scattering Factor and the Conductivity Mobility in Ultra Pure p-Type Silicon at Low Temperatures.

    DTIC Science & Technology

    1983-04-01

    required by security considerations, contractual obligations, or notice on a specific document. Unclassified SECURITY CLASS’FICATION OF THIS PAGE ("W a Dfat ...diamond structure, fraction- al translations in a unit cell are too small on the macroscopic scale to influence the results of experimental

  16. Catastrophic degradation of the interface of epitaxial silicon carbide on silicon at high temperatures

    NASA Astrophysics Data System (ADS)

    Pradeepkumar, Aiswarya; Mishra, Neeraj; Kermany, Atieh Ranjbar; Boeckl, John J.; Hellerstedt, Jack; Fuhrer, Michael S.; Iacopi, Francesca

    2016-07-01

    Epitaxial cubic silicon carbide on silicon is of high potential technological relevance for the integration of a wide range of applications and materials with silicon technologies, such as micro electro mechanical systems, wide-bandgap electronics, and graphene. The hetero-epitaxial system engenders mechanical stresses at least up to a GPa, pressures making it extremely challenging to maintain the integrity of the silicon carbide/silicon interface. In this work, we investigate the stability of said interface and we find that high temperature annealing leads to a loss of integrity. High-resolution transmission electron microscopy analysis shows a morphologically degraded SiC/Si interface, while mechanical stress measurements indicate considerable relaxation of the interfacial stress. From an electrical point of view, the diode behaviour of the initial p-Si/n-SiC junction is catastrophically lost due to considerable inter-diffusion of atoms and charges across the interface upon annealing. Temperature dependent transport measurements confirm a severe electrical shorting of the epitaxial silicon carbide to the underlying substrate, indicating vast predominance of the silicon carriers in lateral transport above 25 K. This finding has crucial consequences on the integration of epitaxial silicon carbide on silicon and its potential applications.

  17. Increased Photoconductivity Lifetime in GaAs Nanowires by Controlled n-Type and p-Type Doping.

    PubMed

    Boland, Jessica L; Casadei, Alberto; Tütüncüoglu, Gözde; Matteini, Federico; Davies, Christopher L; Jabeen, Fauzia; Joyce, Hannah J; Herz, Laura M; Fontcuberta I Morral, Anna; Johnston, Michael B

    2016-04-26

    Controlled doping of GaAs nanowires is crucial for the development of nanowire-based electronic and optoelectronic devices. Here, we present a noncontact method based on time-resolved terahertz photoconductivity for assessing n- and p-type doping efficiency in nanowires. Using this technique, we measure extrinsic electron and hole concentrations in excess of 10(18) cm(-3) for GaAs nanowires with n-type and p-type doped shells. Furthermore, we show that controlled doping can significantly increase the photoconductivity lifetime of GaAs nanowires by over an order of magnitude: from 0.13 ns in undoped nanowires to 3.8 and 2.5 ns in n-doped and p-doped nanowires, respectively. Thus, controlled doping can be used to reduce the effects of parasitic surface recombination in optoelectronic nanowire devices, which is promising for nanowire devices, such as solar cells and nanowire lasers.

  18. P-Type Zno:. as Obtained by Ion Implantation of AS+ with Post-Implantation Annealing in Oxygen Radicals

    NASA Astrophysics Data System (ADS)

    Georgobiani, A. N.; Demin, V. I.; Kotlyarevsky, M. B.; Rogozin, I. V.; Marakhovsky, A. V.

    2004-07-01

    Zinc oxide is the promising material for creation of the new generation of detectors for particle physics and radiation dosimetry. It has been shown that ion implantation of arsenic into zinc oxide film (arsenic is an acceptor impurity in ZnO) can result in formation of the p-type conductivity only in case of annealing in the flux of atomic oxygen. The ion implantation and the following annealing had influenced not only electrical properties of ZnO:As+ layers, but also their photoluminescence spectra. The ultraviolet luminescence band with the maximum at 3.33. eV corresponding to the AsO acceptor center had been clearly observed in the spectra of ZnO films implanted by As+ ions. The optimal temperature range of annealing in the atomic oxygen flux, required for obtaining of p-type conductivity in ZnO films, had been determined.

  19. Optical properties of antimony-doped p-type ZnO films fabricated by pulsed laser deposition

    SciTech Connect

    Pan, X. H.; Guo, W.; Pan, X. Q.; Ye, Z. Z.; He, H. P.; Liu, B.; Che, Y.

    2009-06-01

    We investigated optical properties of Sb-doped p-type ZnO films grown on n-Si (100) substrates by oxygen plasma-assisted pulsed laser deposition. Two acceptor states, with the acceptor levels of 161 and 336 meV, are identified by well-resolved photoluminescence spectra. Under oxygen-rich conditions, the deep acceptor in Sb-doped ZnO film is Zn vacancy. The shallow acceptor is Sb{sub Zn}-2V{sub Zn} complex induced by Sb doping. The origin of p-type behavior in Sb-doped ZnO has been ascribed to the formation of Sb{sub Zn}-2V{sub Zn} complex.

  20. Search for Pauli exclusion principle violating atomic transitions and electron decay with a p-type point contact germanium detector

    SciTech Connect

    Abgrall, N.; Arnquist, I. J.; Avignone, F. T.; Barabash, A. S.; Bertrand, F. E.; Bradley, A. W.; Brudanin, V.; Busch, M.; Buuck, M.; Caldwell, A. S.; Chan, Y. -D.; Christofferson, C. D.; Chu, P. -H.; Cuesta, C.; Detwiler, J. A.; Dunagan, C.; Efremenko, Yu.; Ejiri, H.; Elliott, S. R.; Finnerty, P. S.; Galindo-Uribarri, A.; Gilliss, T.; Giovanetti, G. K.; Goett, J.; Green, M. P.; Gruszko, J.; Guinn, I. S.; Guiseppe, V. E.; Henning, R.; Hoppe, E. W.; Howard, S.; Howe, M. A.; Jasinski, B. R.; Keeter, K. J.; Kidd, M. F.; Konovalov, S. I.; Kouzes, R. T.; LaFerriere, B. D.; Leon, J.; MacMullin, J.; Martin, R. D.; Massarczyk, R.; Meijer, S. J.; Mertens, S.; Orrell, J. L.; O’Shaughnessy, C.; Poon, A. W. P.; Radford, D. C.; Rager, J.; Rielage, K.; Robertson, R. G. H.; Romero-Romero, E.; Shanks, B.; Shirchenko, M.; Suriano, A. M.; Tedeschi, D.; Trimble, J. E.; Varner, R. L.; Vasilyev, S.; Vetter, K.; Vorren, K.; White, B. R.; Wilkerson, J. F.; Wiseman, C.; Xu, W.; Yakushev, E.; Yu, C. -H.; Yumatov, V.; Zhitnikov, I.

    2016-11-11

    A search for Pauli-exclusion-principle-violating K electron transitions was performed using 89.5 kg-d of data collected with a p-type point contact high-purity germanium detector operated at the Kimballton Underground Research Facility. A lower limit on the transition lifetime of s at 90% C.L. was set by looking for a peak at 10.6 keV resulting from the X-ray and Auger electrons present following the transition. A similar analysis was done to look for the decay of atomic K-shell electrons into neutrinos, resulting in a lower limit of s at 90% C.L. It is estimated that the Majorana Demonstrator, a 44 kg array of p-type point contact detectors that will search for the neutrinoless double-beta decay of Ge, could improve upon these exclusion limits by an order of magnitude after three years of operation.

  1. Gas sensing properties and p-type response of ALD TiO2 coated carbon nanotubes.

    PubMed

    Marichy, Catherine; Donato, Nicola; Latino, Mariangela; Willinger, Marc Georg; Tessonnier, Jean-Philippe; Neri, Giovanni; Pinna, Nicola

    2015-01-16

    Amorphous titanium dioxide-coated carbon nanotubes (CNTs) were prepared by atomic layer deposition (ALD) and investigated as sensing layers for resistive NO2 and O2 gas sensors. By varying ALD process conditions and CNT structure, heterostructures with different metal oxide grain size, morphology and coating thickness were synthesized. Higher responses were observed with homogeneous and continuous 5.5 nm thick films onto CNTs at an operating temperature of 150 °C, while CNTs decorated with either discontinuous film or TiO2 nanoparticles showed a weak response close to the one of device made of bare CNTs. An unexpected p-type behavior in presence of the target gas was also noticed, independently of the metal oxide morphology and thickness. Based on previous works, hypotheses were made in order to explain the p-type behavior of TiO2/CNT sensors.

  2. Heavy p-type doping of ZnSe thin films using Cu2Se in pulsed laser deposition

    NASA Astrophysics Data System (ADS)

    Zhang, Xiaojun; Man Yu, Kin; Kronawitter, Coleman X.; Ma, Zhixun; Yu, Peter Y.; Mao, Samuel S.

    2012-07-01

    Undoped, Cu-doped, Se-enriched, and Cu2Se-doped ZnSe films have been grown on fused quartz substrates by pulsed laser deposition. While the other films are highly resistive, Cu2Se-doped ZnSe films are p-type conducting with hole concentrations of ˜1.1 × 1019 cm-3 and resistivities of ˜0.098 Ω cm (compared with previous reports of ˜1×1018 cm-3 and ˜0.75 Ω cm). The exceptional heavy p-type doping of ZnSe films can be attributed to substitution of Zn atoms with Cu while limiting selenium-vacancy-associated compensating defects with additional selenium. This work is of importance to solve doping difficulties and contact problems of wide-bandgap semiconductors.

  3. Odd-Integer Quantum Hall States and Giant Spin Susceptibility in p -Type Few-Layer WSe2

    NASA Astrophysics Data System (ADS)

    Xu, Shuigang; Shen, Junying; Long, Gen; Wu, Zefei; Bao, Zhi-qiang; Liu, Cheng-Cheng; Xiao, Xiao; Han, Tianyi; Lin, Jiangxiazi; Wu, Yingying; Lu, Huanhuan; Hou, Jianqiang; An, Liheng; Wang, Yuanwei; Cai, Yuan; Ho, K. M.; He, Yuheng; Lortz, Rolf; Zhang, Fan; Wang, Ning

    2017-02-01

    We fabricate high-mobility p -type few-layer WSe2 field-effect transistors and surprisingly observe a series of quantum Hall (QH) states following an unconventional sequence predominated by odd-integer states under a moderate strength magnetic field. By tilting the magnetic field, we discover Landau level crossing effects at ultralow coincident angles, revealing that the Zeeman energy is about 3 times as large as the cyclotron energy near the valence band top at the Γ valley. This result implies the significant roles played by the exchange interactions in p -type few-layer WSe2 , in which itinerant or QH ferromagnetism likely occurs. Evidently, the Γ valley of few-layer WSe2 offers a unique platform with unusually heavy hole carriers and a substantially enhanced g factor for exploring strongly correlated phenomena.

  4. Effects of abnormal cell-to-cell interference on p-type floating gate and control gate NAND flash memory

    NASA Astrophysics Data System (ADS)

    Kim, Yong Jun; Kang, Jun Geun; Lee, Byungin; Cho, Gyu-Seog; Park, Sung-Kye; Choi, Woo Young

    2014-01-01

    Abnormal cell-to-cell interference occurring in NAND flash memory has been investigated. In the case of extremely downscaled NAND flash memory, cell-to-cell interference increases abnormally. The abnormal cell-to-cell interference has been observed in a p-type floating gate (FG)/control gate (CG) cells for the first time. It has been found that the depletion region variation leads to the abnormal cell-to-cell interference. The depletion region variation of FG and CG is determined by state of neighbor cells. The depletion region variation affects CG-to-FG coupling capacitance and threshold voltage variation (ΔVT). Finally, it is observed that there is a symmetrical relationship between n- and p-type FG/CG NAND flash memory in terms of cell-to-cell interference.

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

    SciTech Connect

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

    2008-09-15

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

  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. GaN-based light emitting diodes using p-type trench structure for improving internal quantum efficiency

    NASA Astrophysics Data System (ADS)

    Kim, Garam; Sun, Min-Chul; Kim, Jang Hyun; Park, Euyhwan; Park, Byung-Gook

    2017-01-01

    In order to improve the internal quantum efficiency of GaN-based LEDs, a LED structure featuring a p-type trench in the multi-quantum well (MQW) is proposed. This structure has effects on spreading holes into the MQW and reducing the quantum-confined stark effect (QCSE). In addition, two simple fabrication methods using electron-beam (e-beam) lithography or selective wet etching for manufacturing the p-type structure are also proposed. From the measurement results of the manufactured GaN-based LEDs, it is confirmed that the proposed structure using e-beam lithography or selective wet etching shows improved light output power compared to the conventional structure because of more uniform hole distribution. It is also confirmed that the proposed structure formed by e-beam lithography has a significant effect on strain relaxation and reduction in the QCSE from the electro-luminescence measurement.

  8. Analysis of Photoluminescence Thermal Quenching: Guidance for the Design of Highly Effective p-type Doping of Nitrides

    PubMed Central

    Liu, Zhiqiang; Huang, Yang; Yi, Xiaoyan; Fu, Binglei; Yuan, Guodong; Wang, Junxi; Li, Jinmin; Zhang, Yong

    2016-01-01

    A contact-free diagnostic technique for examining position of the impurity energy level of p-type dopants in nitride semiconductors was proposed based on photoluminescence thermal quenching. The Mg ionization energy was extracted by the phenomenological rate-equation model we developed. The diagnostic technique and analysis model reported here are priorities for the design of highly effective p-doping of nitrides and could also be used to explain the abnormal and seldom analyzed low characteristic temperature T0 (about 100 K) of thermal quenching in p-type nitrides systems. An In-Mg co-doped GaN system is given as an example to prove the validity of our methods. Furthermore, a hole concentration as high as 1.94 × 1018 cm−3 was achieved through In-Mg co-doping, which is nearly one order of magnitude higher than typically obtained in our lab. PMID:27550805

  9. Low stress tungsten films by silicon reduction of WF/sub 6/

    SciTech Connect

    Joshi, R.V.

    1988-06-14

    A method for providing low stress refractory metal layers selected from the group consisting of tungsten and molybdenum on a substrate is described comprising the steps of: providing an initial area of silicon material on the substrate, exposing the initial area of silicon material to a gaseous refractory metal hexafluoride selected from the group consisting of tungsten hexafluoride and molybdenum hexafluoride to replace at least the surface of the silicon material with the refractory metal, depositing a subsequent layer of the silicon material on the refractory metal using plasma deposition such that the bombardment of silicon ions reduces stress in the refractory metal layer, the silicon layer having a thickness less than the thickness at which the replacment of the silicon to the refractory metal becomes self limiting; and, exposing the layer of silicon material to the gaseous refractory metal hexafluoride to replace the silicon material with the refractory metal.

  10. Plasmonic Properties of Silicon Nanocrystals Doped with Boron and Phosphorus.

    PubMed

    Kramer, Nicolaas J; Schramke, Katelyn S; Kortshagen, Uwe R

    2015-08-12

    Degenerately doped silicon nanocrystals are appealing plasmonic materials due to silicon's low cost and low toxicity. While surface plasmonic resonances of boron-doped and phosphorus-doped silicon nanocrystals were recently observed, there currently is poor understanding of the effect of surface conditions on their plasmonic behavior. Here, we demonstrate that phosphorus-doped silicon nanocrystals exhibit a plasmon resonance immediately after their synthesis but may lose their plasmonic response with oxidation. In contrast, boron-doped nanocrystals initially do not exhibit plasmonic response but become plasmonically active through postsynthesis oxidation or annealing. We interpret these results in terms of substitutional doping being the dominant doping mechanism for phosphorus-doped silicon nanocrystals, with oxidation-induced defects trapping free electrons. The behavior of boron-doped silicon nanocrystals is more consistent with a strong contribution of surface doping. Importantly, boron-doped silicon nanocrystals exhibit air-stable plasmonic behavior over periods of more than a year.

  11. Influence of H 2SO 4 concentration on lead-acid battery performance . H-type and P-type batteries

    NASA Astrophysics Data System (ADS)

    Pavlov, D.; Naidenov, V.; Ruevski, S.

    concentration of H 2SO 4 in them: H-type batteries with CH2SO4 < 1.24 s .g . , and P-type batteries with CH2SO4 > 1.24 s .g . Currently, VRLA batteries of the P-type are commercially produced. H-type batteries have lower initial capacity than the rated value, but long cycle life and allow to be charged at lower voltages (e.g. 2.27 V per cell). P-type batteries have initial capacity higher than or equal to the rated value, but short cycle life and require high charge voltages.

  12. Consequences of Atomic Oxygen Interaction With Silicone and Silicone Contamination on Surfaces in Low Earth Orbit

    NASA Technical Reports Server (NTRS)

    Banks, Bruce A.; deGroh, Kim K.; Rutledge, Sharon K.; Haytas, Christy A.

    1999-01-01

    The exposure of silicones to atomic oxygen in low Earth orbit causes oxidation of the surface, resulting in conversion of silicone to silica. This chemical conversion increases the elastic modulus of the surface and initiates the development of a tensile strain. Ultimately, with sufficient exposure, tensile strain leads to cracking of the surface enabling the underlying unexposed silicone to be converted to silica resulting in additional depth and extent of cracking. The use of silicone coatings for the protection of materials from atomic oxygen attack is limited because of the eventual exposure of underlying unprotected polymeric material due to deep tensile stress cracking of the oxidized silicone. The use of moderate to high volatility silicones in low Earth orbit has resulted in a silicone contamination arrival at surfaces which are simultaneously being bombarded with atomic oxygen, thus leading to conversion of the silicone contaminant to silica. As a result of these processes, a gradual accumulation of contamination occurs leading to deposits which at times have been up to several microns thick (as in the case of a Mir solar array after 10 years in space). The contamination species typically consist of silicon, oxygen and carbon. which in the synergistic environment of atomic oxygen and UV radiation leads to increased solar absorptance and reduced solar transmittance. A comparison of the results of atomic oxygen interaction with silicones and silicone contamination will be presented based on the LDEF, EOIM-111, Offeq-3 spacecraft and Mir solar array in-space results. The design of a contamination pin-hole camera space experiment which uses atomic oxygen to produce an image of the sources of silicone contamination will also be presented.

  13. p-type Li, Cu-codoped NiOx hole-transporting layer for efficient planar perovskite solar cells.

    PubMed

    Liu, Ming-Hua; Zhou, Zheng-Ji; Zhang, Pan-Pan; Tian, Qing-Wen; Zhou, Wen-Hui; Kou, Dong-Xing; Wu, Si-Xin

    2016-10-31

    p-type inorganic hole transport materials of Li, Cu-codoped NiOx films were deposited using a simple solution-based process. The as-prepared films were used as hole selective contacts for lead halide perovskite solar cell. An enhanced power conversion efficiency of 14.53% has been achieved due to the improved electrical conductivity and optical transmittance of the Li, Cu-codoped NiOx electrode interlayer.

  14. Stable ohmic contacts to thin films of p-type tellurium-containing II-VI semiconductors

    SciTech Connect

    Szabo, L.F.; Biter, W.J.

    1988-04-05

    A photovolatic device is described comprising: a light transmissive substrate; an electrically conductive, transparent layer disposed on the substrate as a first electrode; a layer of a first semiconductor disposed on the first electrode; a p-type thin film of a tellurium-containing II-VI semiconductor disposed on the first semiconductor to form a photoresponsive junction with it; and a second electrode contacting the thin film.

  15. S-TYPE AND P-TYPE HABITABILITY IN STELLAR BINARY SYSTEMS: A COMPREHENSIVE APPROACH. II. ELLIPTICAL ORBITS

    SciTech Connect

    Cuntz, M.

    2015-01-10

    In the first paper of this series, a comprehensive approach has been provided for the study of S-type and P-type habitable regions in stellar binary systems, which was, however, restricted to circular orbits of the stellar components. Fortunately, a modest modification of the method also allows for the consideration of elliptical orbits, which of course entails a much broader range of applicability. This augmented method is presented here, and numerous applications are conveyed. In alignment with Paper I, the selected approach considers a variety of aspects, which comprise the consideration of a joint constraint including orbital stability and a habitable region for a possible system planet through the stellar radiative energy fluxes ({sup r}adiative habitable zone{sup ;} RHZ). The devised method is based on a combined formalism for the assessment of both S-type and P-type habitability; in particular, mathematical criteria are deduced for which kinds of systems S-type and P-type habitable zones are realized. If the RHZs are truncated by the additional constraint of orbital stability, the notation of ST-type and PT-type habitability applies. In comparison to the circular case, it is found that in systems of higher eccentricity, the range of the RHZs is significantly reduced. Moreover, for a considerable number of models, the orbital stability constraint also reduces the range of S-type and P-type habitability. Nonetheless, S-, P-, ST-, and PT-type habitability is identified for a considerable set of system parameters. The method as presented is utilized for BinHab, an online code available at The University of Texas at Arlington.

  16. Theory of the Carrier Fermi Energy and Density of States of n- and p-TYPE SnTe

    NASA Astrophysics Data System (ADS)

    Das, R. K.; Mohapatro, S.

    In the present work we theoretically develop a kṡπ model to calculate the carrier electronic structure for both n- and p-type SnTe. Here π is the momentum operator in the presence of the spin-orbit interaction. The work is an extension of the theory developed for n- and p-PbTe earlier by one of the authors to evaluate the Fermi energy and the density of states (DOS). We consider a six-level energy basis for SnTe, as proposed by Bernick and Kleinman. One set of calculations was done by diagonalizing the kṡπ Hamiltonian matrix for the band-edge states and treating the far bands using perturbation theory. In the second set we have rediagonalized the kṡπ Hamiltonian matrix for the band edge states, treating the first diagonalization as the basis. The far bands are, as usual, included through perturbation. We have compared the results of both the sets. Results obtained for n- and p-type SnTe are also compared with that of n- and p-type PbTe. The similarities and contrasts are discussed. An indirect comparison with the DOS of the metallic tin suggests that the calculations are fairly reasonable. The results are also compared with some recent results for SnTe.

  17. Ultrasensitive Room-Temperature Operable Gas Sensors Using p-Type Na:ZnO Nanoflowers for Diabetes Detection.

    PubMed

    Jaisutti, Rawat; Lee, Minkyung; Kim, Jaeyoung; Choi, Seungbeom; Ha, Tae-Jun; Kim, Jaekyun; Kim, Hyoungsub; Park, Sung Kyu; Kim, Yong-Hoon

    2017-03-15

    Ultrasensitive room-temperature operable gas sensors utilizing the photocatalytic activity of Na-doped p-type ZnO (Na:ZnO) nanoflowers (NFs) are demonstrated as a promising candidate for diabetes detection. The flowerlike Na:ZnO nanoparticles possessing ultrathin hierarchical nanosheets were synthesized by a facile solution route at a low processing temperature of 40 °C. It was found that the Na element acting as a p-type dopant was successfully incorporated in the ZnO lattice. On the basis of the synthesized p-type Na:ZnO NFs, room-temperature operable chemiresistive-type gas sensors were realized, activated by ultraviolet (UV) illumination. The Na:ZnO NF gas sensors exhibited high gas response (S of 3.35) and fast response time (∼18 s) and recovery time (∼63 s) to acetone gas (100 ppm, UV intensity of 5 mW cm(-2)), and furthermore, subppm level (0.2 ppm) detection was achieved at room temperature, which enables the diagnosis of various diseases including diabetes from exhaled breath.

  18. ESR study of p-type natural 2H-polytype MoS2 crystals: The As acceptor activity

    NASA Astrophysics Data System (ADS)

    Stesmans, A.; Iacovo, S.; Afanas'ev, V. V.

    2016-10-01

    Low-temperature (T = 1.7-77 K) multi frequency electron spin resonance (ESR) study on p-type 2H-polytype geological MoS2 crystals reveals p-type doping predominantly originating from As atoms substituting for S sites in densities of (2.4 ± 0.2) × 1017 cm-3. Observation of a "half field"(g ˜ 3.88) signal firmly correlating with the central Zeeman As accepter signal indicates the presence of spin S > ½ As agglomerates, which together with the distinct multicomponent makeup of the Zeeman signal points to manifest non-uniform As doping; only ˜13% of the total As response originates from individual decoupled As dopants. From ESR monitoring the latter vs. T, an activation energy Ea = (0.7 ± 0.2) meV is obtained. This unveils As as a noticeable shallow acceptor dopant, appropriate for realization of effective p-type doping in targeted 2D MoS2-based switching devices.

  19. Characterization of Al-As codoped p-type ZnO films by magnetron cosputtering deposition

    SciTech Connect

    Yun, Eui-Jung; Park, Hyeong-Sik; Lee, Kyu H.; Nam, Hyoung G.; Jung, Myunghee

    2008-04-01

    We report the preparation of Al-As codoped p-type ZnO films by rf magnetron cosputtering deposition. The p-type conductivity of the films was revealed by Hall measurements, x-ray photoelectron spectroscopy (XPS), and photoluminescence measurements after being annealed in O{sub 2}. It was observed by XPS that Al content increased with increasing AlAs target power from 80 to 160 W and reached a maximum value at an AlAs target power of 160 W. Hole concentration decreased with increasing Al content. With increasing AlAs target power greater than 160 W, the samples exhibit increases in As and O contents and decreases in Al and Zn contents, which contribute to the increase in hole concentration. A high hole concentration of 2.354x10{sup 20} cm{sup -3}, a low resistivity of 2.122x10{sup -2} {omega} cm, and a Hall mobility of 0.13 cm{sup 2}/V s for the films with high As content of 16.59% were obtained. XPS has also been used to address the unresolved issues related to the p-type formation mechanism of As-doped ZnO, supporting that the acceptor is As{sub Zn}-2V{sub Zn}.

  20. Comparative chemical genomics reveal that the spiroindolone antimalarial KAE609 (Cipargamin) is a P-type ATPase inhibitor

    PubMed Central

    Goldgof, Gregory M.; Durrant, Jacob D.; Ottilie, Sabine; Vigil, Edgar; Allen, Kenneth E.; Gunawan, Felicia; Kostylev, Maxim; Henderson, Kiersten A.; Yang, Jennifer; Schenken, Jake; LaMonte, Gregory M.; Manary, Micah J.; Murao, Ayako; Nachon, Marie; Stanhope, Rebecca; Prescott, Maximo; McNamara, Case W.; Slayman, Carolyn W.; Amaro, Rommie E.; Suzuki, Yo; Winzeler, Elizabeth A.

    2016-01-01

    The spiroindolones, a new class of antimalarial medicines discovered in a cellular screen, are rendered less active by mutations in a parasite P-type ATPase, PfATP4. We show here that S. cerevisiae also acquires mutations in a gene encoding a P-type ATPase (ScPMA1) after exposure to spiroindolones and that these mutations are sufficient for resistance. KAE609 resistance mutations in ScPMA1 do not confer resistance to unrelated antimicrobials, but do confer cross sensitivity to the alkyl-lysophospholipid edelfosine, which is known to displace ScPma1p from the plasma membrane. Using an in vitro cell-free assay, we demonstrate that KAE609 directly inhibits ScPma1p ATPase activity. KAE609 also increases cytoplasmic hydrogen ion concentrations in yeast cells. Computer docking into a ScPma1p homology model identifies a binding mode that supports genetic resistance determinants and in vitro experimental structure-activity relationships in both P. falciparum and S. cerevisiae. This model also suggests a shared binding site with the dihydroisoquinolones antimalarials. Our data support a model in which KAE609 exerts its antimalarial activity by directly interfering with P-type ATPase activity. PMID:27291296

  1. Thermoelectric properties of p-type PbTe/Ag{sub 2}Te bulk composites by extrinsic phase mixing

    SciTech Connect

    Lee, Min Ho; Rhyee, Jong-Soo

    2015-12-15

    We investigated the thermoelectric properties of PbTe/Ag{sub 2}Te bulk composites, synthesized by hand milling, mixing, and hot press sintering. From x-ray diffraction and energy dispersive x-ray spectroscopy measurements, we observed Ag{sub 2}Te phase separation in the PbTe matrix without Ag atom diffusion. In comparison with previously reported pseudo-binary (PbTe){sub 1−x}(Ag{sub 2}Te){sub x} composites, synthesized by high temperature phase separation, the PbTe/Ag{sub 2}Te bulk composites fabricated with a low temperature phase mixing process give rise to p-type conduction of carriers with significantly decreased electrical conductivity. This indicates that Ag atom diffusion in the PbTe matrix changes the sign of the Seebeck coefficient to n-type and also increases the carrier concentration. Effective p-type doping with low temperature phase separation by mixing and hot press sintering can enhance the thermoelectric performance of PbTe/Ag{sub 2}Te bulk composites, which can be used as a p-type counterpart of n-type (PbTe){sub 1−x}(Ag{sub 2}Te){sub x} bulk composites.

  2. MoS₂ P-type transistors and diodes enabled by high work function MoOx contacts.

    PubMed

    Chuang, Steven; Battaglia, Corsin; Azcatl, Angelica; McDonnell, Stephen; Kang, Jeong Seuk; Yin, Xingtian; Tosun, Mahmut; Kapadia, Rehan; Fang, Hui; Wallace, Robert M; Javey, Ali

    2014-03-12

    The development of low-resistance source/drain contacts to transition-metal dichalcogenides (TMDCs) is crucial for the realization of high-performance logic components. In particular, efficient hole contacts are required for the fabrication of p-type transistors with MoS2, a model TMDC. Previous studies have shown that the Fermi level of elemental metals is pinned close to the conduction band of MoS2, thus resulting in large Schottky barrier heights for holes with limited hole injection from the contacts. Here, we show that substoichiometric molybdenum trioxide (MoOx, x < 3), a high work function material, acts as an efficient hole injection layer to MoS2 and WSe2. In particular, we demonstrate MoS2 p-type field-effect transistors and diodes by using MoOx contacts. We also show drastic on-current improvement for p-type WSe2 FETs with MoOx contacts over devices made with Pd contacts, which is the prototypical metal used for hole injection. The work presents an important advance in contact engineering of TMDCs and will enable future exploration of their performance limits and intrinsic transport properties.

  3. Breast Implants: Saline vs. Silicone

    MedlinePlus

    ... to women of any age for breast reconstruction. Silicone breast implants Silicone implants are pre-filled with ... likely be inserted at the same time. Ruptured silicone implant If a silicone breast implant ruptures, you ...

  4. Electron and photon degradation in aluminum, gallium and boron doped float zone silicon solar cells

    NASA Technical Reports Server (NTRS)

    Rahilly, W. P.; Scott-Monck, J.; Anspaugh, B.; Locker, D.

    1976-01-01

    Solar cells fabricated from Al, Ga and B doped Lopex silicon over a range of resistivities were tested under varying conditions of 1 MeV electron fluence, light exposures and thermal cycling. Results indicate that Al and Ga can replace B as a P type dopant to yield improved solar cell performance.

  5. Reactive Melt Infiltration Of Silicon Into Porous Carbon

    NASA Technical Reports Server (NTRS)

    Behrendt, Donald R.; Singh, Mrityunjay

    1994-01-01

    Report describes study of synthesis of silicon carbide and related ceramics by reactive melt infiltration of silicon and silicon/molybdenum alloys into porous carbon preforms. Reactive melt infiltration has potential for making components in nearly net shape, performed in less time and at lower temperature. Object of study to determine effect of initial pore volume fraction, pore size, and infiltration material on quality of resultant product.

  6. AC Impedance Studies on Metal/Nanoporous Silicon/ p-Silicon Structures

    NASA Astrophysics Data System (ADS)

    Mabrook, M. F.; Ray, A. K.

    2017-04-01

    Alternating current (AC) impedance measurements have been performed on 10- to 15- μm thick porous silicon layers on a (100) p-type silicon ( p(+)Si) substrate with the aluminium (Al) top electrode in a sandwich configuration in the range of 20 Hz-1 MHz and in the temperature ranging between 152 K and 292 K. The ac conductivity σ ac was found to increase with frequency f according to the universal power law: σ_{{ac}} = Afs where the exponent s is a frequency and temperature-dependent quantity. A hopping process is found to be dominant at low temperatures and high frequencies, while a thermally activated free band process is responsible for conduction at higher temperatures. Capacitance is found to decrease with frequency but increase with temperature. Frequency dependence of the loss tangent is observed with a temperature-dependent minimum value.

  7. AC Impedance Studies on Metal/Nanoporous Silicon/p-Silicon Structures

    NASA Astrophysics Data System (ADS)

    Mabrook, M. F.; Ray, A. K.

    2016-11-01

    Alternating current (AC) impedance measurements have been performed on 10- to 15-μm thick porous silicon layers on a (100) p-type silicon (p(+)Si) substrate with the aluminium (Al) top electrode in a sandwich configuration in the range of 20 Hz-1 MHz and in the temperature ranging between 152 K and 292 K. The ac conductivity σ ac was found to increase with frequency f according to the universal power law: σ_{ac} = Afs where the exponent s is a frequency and temperature-dependent quantity. A hopping process is found to be dominant at low temperatures and high frequencies, while a thermally activated free band process is responsible for conduction at higher temperatures. Capacitance is found to decrease with frequency but increase with temperature. Frequency dependence of the loss tangent is observed with a temperature-dependent minimum value.

  8. Process for producing silicon

    DOEpatents

    Olson, Jerry M.; Carleton, Karen L.

    1984-01-01

    A process for producing silicon includes forming an alloy of copper and silicon and positioning the alloy in a dried, molten salt electrolyte to form a solid anode structure therein. An electrically conductive cathode is placed in the electrolyte for plating silicon thereon. The electrolyte is then purified to remove dissolved oxides. Finally, an electrical potential is applied between the anode and cathode in an amount sufficient to form substantially pure silicon on the cathode in the form of substantially dense, coherent deposits.

  9. Metal assisted anodic etching of silicon

    NASA Astrophysics Data System (ADS)

    Lai, Chang Quan; Zheng, Wen; Choi, W. K.; Thompson, Carl V.

    2015-06-01

    Metal assisted anodic etching (MAAE) of Si in HF, without H2O2, is demonstrated. Si wafers were coated with Au films, and the Au films were patterned with an array of holes. A Pt mesh was used as the cathode while the anodic contact was made through either the patterned Au film or the back side of the Si wafer. Experiments were carried out on P-type, N-type, P+-type and N+-type Si wafers and a wide range of nanostructure morphologies were observed, including solid Si nanowires, porous Si nanowires, a porous Si layer without Si nanowires, and porous Si nanowires on a thick porous Si layer. Formation of wires was the result of selective etching at the Au-Si interface. It was found that when the anodic contact was made through P-type or P+-type Si, regular anodic etching due to electronic hole injection leads to formation of porous silicon simultaneously with metal assisted anodic etching. When the anodic contact was made through N-type or N+-type Si, generation of electronic holes through processes such as impact ionization and tunnelling-assisted surface generation were required for etching. In addition, it was found that metal assisted anodic etching of Si with the anodic contact made through the patterned Au film essentially reproduces the phenomenology of metal assisted chemical etching (MACE), in which holes are generated through metal assisted reduction of H2O2 rather than current flow. These results clarify the linked roles of electrical and chemical processes that occur during electrochemical etching of Si.Metal assisted anodic etching (MAAE) of Si in HF, without H2O2, is demonstrated. Si wafers were coated with Au films, and the Au films were patterned with an array of holes. A Pt mesh was used as the cathode while the anodic contact was made through either the patterned Au film or the back side of the Si wafer. Experiments were carried out on P-type, N-type, P+-type and N+-type Si wafers and a wide range of nanostructure morphologies were observed

  10. Electrodeposition of molten silicon

    DOEpatents

    De Mattei, Robert C.; Elwell, Dennis; Feigelson, Robert S.

    1981-01-01

    Silicon dioxide is dissolved in a molten electrolytic bath, preferably comprising barium oxide and barium fluoride. A direct current is passed between an anode and a cathode in the bath to reduce the dissolved silicon dioxide to non-alloyed silicon in molten form, which is removed from the bath.

  11. Efficient Silicon Reactor

    NASA Technical Reports Server (NTRS)

    Bates, H. E.; Hill, D. M.; Jewett, D. N.

    1983-01-01

    High-purity silicon efficiently produced and transferred by continuous two-cycle reactor. New reactor operates in relatively-narrow temperature rate and uses large surfaces area to minimize heat expenditure and processing time in producing silicon by hydrogen reduction of trichlorosilane. Two cycles of reactor consists of silicon production and removal.

  12. Prokaryotic silicon utilizing microorganisms in the biosphere

    NASA Astrophysics Data System (ADS)

    Gupta, D.; Das, S.

    2012-12-01

    Although a little study has been done to determine the silicon utilizing prokaryotes, our previous experiments indicated that almost all Gram-positive bacteria are silicon utilizing; one of them, Streptococci survived exposure on the lunar surface for a long period in experiment done by others. Our initial experiments with these Gram positive microorganisms showed that there were limited growths of these microorganisms on carbon free silicate medium probably with the help of some carry over carbon and nitrogen during cultivation procedures. However, increase in growth rate after repeated subcultures could not be explained at present. The main groups of prokaryotes which were found silicon utilizing microorganisms were Mycobacterium, Bacillus, Nocardia, Streptomyces, Staphylococcus, Streptococcus, Lactobacillus, and Clostridium. In a another previous study by us when silicon level was studied in such grown up cells on carbon "free" silicate medium by electron prove microanalyser, it was found that silicon in cells grown on carbon "free" silicate medium was much higher (24.9%) than those grown on conventional carbon based medium (0.84%). However, these initial findings are encouraging for our future application of this group of organisms on extraterrestrial surfaces for artificial micro-ecosystem formation. It was found that when electropositive elements are less in extraterrestrial situation, then polymerization of silicon-oxygen profusion may occur easily, particularly in carbon and nitrogen paucity in the rocky worlds of the Universe.

  13. Metal assisted anodic etching of silicon.

    PubMed

    Lai, Chang Quan; Zheng, Wen; Choi, W K; Thompson, Carl V

    2015-07-07

    Metal assisted anodic etching (MAAE) of Si in HF, without H2O2, is demonstrated. Si wafers were coated with Au films, and the Au films were patterned with an array of holes. A Pt mesh was used as the cathode while the anodic contact was made through either the patterned Au film or the back side of the Si wafer. Experiments were carried out on P-type, N-type, P(+)-type and N(+)-type Si wafers and a wide range of nanostructure morphologies were observed, including solid Si nanowires, porous Si nanowires, a porous Si layer without Si nanowires, and porous Si nanowires on a thick porous Si layer. Formation of wires was the result of selective etching at the Au-Si interface. It was found that when the anodic contact was made through P-type or P(+)-type Si, regular anodic etching due to electronic hole injection leads to formation of porous silicon simultaneously with metal assisted anodic etching. When the anodic contact was made through N-type or N(+)-type Si, generation of electronic holes through processes such as impact ionization and tunnelling-assisted surface generation were required for etching. In addition, it was found that metal assisted anodic etching of Si with the anodic contact made through the patterned Au film essentially reproduces the phenomenology of metal assisted chemical etching (MACE), in which holes are generated through metal assisted reduction of H2O2 rather than current flow. These results clarify the linked roles of electrical and chemical processes that occur during electrochemical etching of Si.

  14. Interaction between copper and point defects in silicon irradiated with 2-MeV electrons

    NASA Astrophysics Data System (ADS)

    Aboelfotoh, M. O.; Svensson, B. G.

    1995-07-01

    The interaction between copper and irradiation-induced defects in silicon has been investigated with the use of Schottky-barrier structures formed by the deposition of copper on n- and p-type silicon irradiated with 2-MeV electrons at room temperature. It is found that the annealing rate of the divacancy (V2) centers is anomalously high at temperatures below 150 °C in both n- and p-type silicon. This is attributed to passivation of the V2 centers by the highly mobile Cu through the formation of neutral complexes. A prominent level located 0.52 eV above the valence-band edge (Ev) appears in p-type silicon after Cu deposition at room temperature. It is suggested that this level originates from a complex formed by reaction between Cu and the carbon-oxygen centers which give rise to the ``ordinary'' irradiation-induced level at Ev+0.35 eV. This latter level, which is normally stable up to temperatures of ~350 °C, anneals rapidly at 100 °C through the formation of the Cu-associated level at Ev+0.52 eV which disappears upon silicide formation. Furthermore, the present results show that no injection of Si self-interstitials into the silicon substrate takes place during the formation of the metal-rich silicide η'-Cu3Si, contrary to the conclusions of recent studies.

  15. Influence of fluids on the abrasion of silicon by diamond

    NASA Technical Reports Server (NTRS)

    Danyluk, S.

    1982-01-01

    Silicon wafers ((100)-p-type) were abraded at room temperature in acetone, absolute ethanol and water by a pyramid diamond and the resulting groove depth was measured as a function of normal force on the diamond and the absorbed fluids, while all other experimental conditions were held constant. The groove depth rates are in the ratio of 1:2:3 for water, absolute ethanol, and acetone, respectively, for a constant normal force. The groove depth rate is lower when the normal force is decreased. The silicon abraded in the presence of water was chipped as expected for a classical brittle material while the surfaces abraded in the other two fluids showed ductile ploughing as the main mechanism for silicon removal.

  16. 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.

  17. Selective porous silicon formation in buried p + layers

    NASA Astrophysics Data System (ADS)

    Tsao, S. S.; Myers, D. R.; Guilinger, T. R.; Kelly, M. J.; Datye, A. K.

    1987-11-01

    We report a systematic microstructural study of enhanced lateral porous silicon formation in the buried p+ layers of n/p+/p- and p-/p+/p- structures. We find, surprisingly, extremely selective porous silicon formation due to the thin p+ layer in both structures, despite the absence of a p-n junction in the p-/p+/p- structure. The interface between the isolated island and the buried porous silicon layer was always located at the depth where the net p-type dopant concentration was 1-8×1015/cm3. The observed microstructure can largely be understood in terms of a recent model for porous Si formation in uniformly doped Si, proposed by Beale et al. [J. Cryst. Growth 73, 622 (1985)]. However, we also observe, for the first time, important effects unique to a nonuniform dopant concentration.

  18. The role of nanoscale defect features in enhancing the thermoelectric performance of p-type nanostructured SiGe alloys.

    PubMed

    Bathula, Sivaiah; Jayasimhadri, M; Gahtori, Bhasker; Singh, Niraj Kumar; Tyagi, Kriti; Srivastava, A K; Dhar, Ajay

    2015-08-07

    Despite SiGe being one of the most widely studied thermoelectric materials owing to its application in radioisotope thermoelectric generators (RTG), the thermoelectric figure-of merit (ZT) of p-type SiGe is still quite low, resulting in poor device efficiencies. In the present study, we report a substantial enhancement in ZT∼ 1.2 at 900 °C for p-type nanostructured Si80Ge20 alloys by creating several types of defect features within the Si80Ge20 nanostructured matrix in a spectrum of nano to meso-scale dimensions during its nanostructuring, by employing mechanical alloying followed by spark plasma sintering. This enhancement in ZT, which is ∼25% over the existing state-of-the-art value for a p-type nanostructured Si80Ge20 alloy, is primarily due to its ultralow thermal conductivity of ∼2.04 W m(-1) K(-1) at 900 °C, resulting from the scattering of low-to-high wavelength heat-carrying phonons by different types of defect features in a range of nano to meso-scale dimensions in the Si80Ge20 nanostructured matrix. These include point defects, dislocations, isolated amorphous regions, nano-scale grain boundaries and more importantly, the nano to meso-scale residual porosity distributed throughout the Si80Ge20 matrix. These nanoscale multi-dimensional defect features have been characterized by employing scanning and transmission electron microscopy and correlated with the electrical and thermal transport properties, based on which the enhancement of ZT has been discussed.

  19. Design of ternary alkaline-earth metal Sn(II) oxides with potential good p-type conductivity

    SciTech Connect

    Du, Mao -Hua; Singh, David J.; Zhang, Lijun; Li, Yuwei; Xu, Qiaoling; Ma, Yanming; Zheng, Weitao

    2016-04-19

    Oxides with good p-type conductivity have been long sought after to achieve high performance all-oxide optoelectronic devices. Divalent Sn(II) based oxides are promising candidates because of their rather dispersive upper valence bands caused by the Sn-5s/O-2p anti-bonding hybridization. There are so far few known Sn(II) oxides being p-type conductive suitable for device applications. Here, we present via first-principles global optimization structure searches a material design study for a hitherto unexplored Sn(II)-based system, ternary alkaline-earth metal Sn(II) oxides in the stoichiometry of MSn2O3 (M = Mg, Ca, Sr, Ba). We identify two stable compounds of SrSn2O3 and BaSn2O3, which can be stabilized by Sn-rich conditions in phase stability diagrams. Their structures follow the Zintl behaviour and consist of basic structural motifs of SnO3 tetrahedra. Unexpectedly they show distinct electronic properties with band gaps ranging from 1.90 (BaSn2O3) to 3.15 (SrSn2O3) eV, and hole effective masses ranging from 0.87 (BaSn2O3) to above 6.0 (SrSn2O3) m0. Further exploration of metastable phases indicates a wide tunability of electronic properties controlled by the details of the bonding between the basic structural motifs. Lastly, this suggests further exploration of alkaline-earth metal Sn(II) oxides for potential applications requiring good p-type conductivity such as transparent conductors and photovoltaic absorbers.

  20. Design of ternary alkaline-earth metal Sn(II) oxides with potential good p-type conductivity

    DOE PAGES

    Du, Mao -Hua; Singh, David J.; Zhang, Lijun; ...

    2016-04-19

    Oxides with good p-type conductivity have been long sought after to achieve high performance all-oxide optoelectronic devices. Divalent Sn(II) based oxides are promising candidates because of their rather dispersive upper valence bands caused by the Sn-5s/O-2p anti-bonding hybridization. There are so far few known Sn(II) oxides being p-type conductive suitable for device applications. Here, we present via first-principles global optimization structure searches a material design study for a hitherto unexplored Sn(II)-based system, ternary alkaline-earth metal Sn(II) oxides in the stoichiometry of MSn2O3 (M = Mg, Ca, Sr, Ba). We identify two stable compounds of SrSn2O3 and BaSn2O3, which can bemore » stabilized by Sn-rich conditions in phase stability diagrams. Their structures follow the Zintl behaviour and consist of basic structural motifs of SnO3 tetrahedra. Unexpectedly they show distinct electronic properties with band gaps ranging from 1.90 (BaSn2O3) to 3.15 (SrSn2O3) eV, and hole effective masses ranging from 0.87 (BaSn2O3) to above 6.0 (SrSn2O3) m0. Further exploration of metastable phases indicates a wide tunability of electronic properties controlled by the details of the bonding between the basic structural motifs. Lastly, this suggests further exploration of alkaline-earth metal Sn(II) oxides for potential applications requiring good p-type conductivity such as transparent conductors and photovoltaic absorbers.« less

  1. Surface Charge Transfer Doping via Transition Metal Oxides for Efficient p-Type Doping of II-VI Nanostructures.

    PubMed

    Xia, Feifei; Shao, Zhibin; He, Yuanyuan; Wang, Rongbin; Wu, Xiaofeng; Jiang, Tianhao; Duhm, Steffen; Zhao, Jianwei; Lee, Shuit-Tong; Jie, Jiansheng

    2016-11-22

    Wide band gap II-VI nanostructures are important building blocks for new-generation electronic and optoelectronic devices. However, the difficulty of realizing p-type conductivity in these materials via conventional doping methods has severely handicapped the fabrication of p-n homojunctions and complementary circuits, which are the fundamental components for high-performance devices. Herein, by using first-principles density functional theory calculations, we demonstrated a simple yet efficient way to achieve controlled p-type doping on II-VI nanostructures via surface charge transfer doping (SCTD) using high work function transition metal oxides such as MoO3, WO3, CrO3, and V2O5 as dopants. Our calculations revealed that these oxides were capable of drawing electrons from II-VI nanostructures, leading to accumulation of positive charges (holes injection) in the II-VI nanostructures. As a result, Fermi levels of the II-VI nanostructures were shifted toward the valence band regions after surface modifications, along with the large enhancement of work functions. In situ ultraviolet photoelectron spectroscopy and X-ray photoelectron spectroscopy characterizations verified the significant interfacial charge transfer between II-VI nanostructures and surface dopants. Both theoretical calculations and electrical transfer measurements on the II-VI nanostructure-based field-effect transistors clearly showed the p-type conductivity of the nanostructures after surface modifications. Strikingly, II-VI nanowires could undergo semiconductor-to-metal transition by further increasing the SCTD level. SCTD offers the possibility to create a variety of electronic and optoelectronic devices from the II-VI nanostructures via realization of complementary doping.

  2. 1366 Project Silicon: Reclaiming US Silicon PV Leadership

    SciTech Connect

    Lorenz, Adam

    2016-02-16

    1366 Technologies’ Project Silicon addresses two of the major goals of the DOE’s PV Manufacturing Initiative Part 2 program: 1) How to reclaim a strong silicon PV manufacturing presence and; 2) How to lower the levelized cost of electricity (“LCOE”) for solar to $0.05-$0.07/kWh, enabling wide-scale U.S. market adoption. To achieve these two goals, US companies must commercialize disruptive, high-value technologies that are capable of rapid scaling, defensible from foreign competition, and suited for US manufacturing. These are the aims of 1366 Technologies Direct Wafer ™ process. The research conducted during Project Silicon led to the first industrial scaling of 1366’s Direct Wafer™ process – an innovative, US-friendly (efficient, low-labor content) manufacturing process that destroys the main cost barrier limiting silicon PV cost-reductions: the 35-year-old grand challenge of making quality wafers (40% of the cost of modules) without the cost and waste of sawing. The SunPath program made it possible for 1366 Technologies to build its demonstration factory, a key and critical step in the Company’s evolution. The demonstration factory allowed 1366 to build every step of the process flow at production size, eliminating potential risk and ensuring the success of the Company’s subsequent scaling for a 1 GW factory to be constructed in Western New York in 2016 and 2017. Moreover, the commercial viability of the Direct Wafer process and its resulting wafers were established as 1366 formed key strategic partnerships, gained entry into the $8B/year multi-Si wafer market, and installed modules featuring Direct Wafer products – the veritable proving grounds for the technology. The program also contributed to the development of three Generation 3 Direct Wafer furnaces. These furnaces are the platform for copying intelligently and preparing our supply chain – large-scale expansion will not require a bigger machine but more machines. SunPath filled the

  3. 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.

  4. Liquid-phase-deposited siloxane-based capping layers for silicon solar cells

    NASA Astrophysics Data System (ADS)

    Veith-Wolf, Boris; Wang, Jianhui; Hannu-Kuure, Milja; Chen, Ning; Hadzic, Admir; Williams, Paul; Leivo, Jarkko; Karkkainen, Ari; Schmidt, Jan

    2015-02-01

    We apply non-vacuum processing to deposit dielectric capping layers on top of ultrathin atomic-layer-deposited aluminum oxide (AlOx) 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 AlOx/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. Growth and characterization of Czochralski-grown n and p-type GaAs for space solar cell substrates

    NASA Technical Reports Server (NTRS)

    Chen, R. T.

    1983-01-01

    Progress in LEC (liquid encapsulated Czochralski) crystal growth techniques for producing high-quality, 3-inch-diameter, n- and p-type GaAs crystals suitable for solar cell applications is described. The LEC crystals with low dislocation densities and background impurities, high electrical mobilities, good dopant uniformity, and long diffusion lengths were reproducibly grown through control of the material synthesis, growth and doping conditions. The capability for producing these large-area, high-quality substrates should positively impact the manufacturability of highly efficiency, low cost, radiation-hard GaAs solar cells.

  6. Laser drilling induced electrical type inversion in vacancy-doped p-type HgCdTe

    NASA Astrophysics Data System (ADS)

    Zha, F. X.; Zhou, S. M.; Ma, H. L.; Yin, F.; Zhang, B.; Li, T. X.; Shao, J.; Shen, X. C.

    2008-10-01

    Femtosecond laser was used to generate micrometer-sized holes in vacancy-doped p type mercury cadmium telluride (HgCdTe). Characterization by laser beam induced current (LBIC) microscope shows obvious electrical type inversion around each hole. Both the intensity of the LBIC signals and the spatial dimension of the type-inversed regions are well comparable with those of n-on-p HgCdTe photodiodes formed by the conventional ion milling technique. The observation demonstrates the potential of laser drilling to be a new tool in fabricating HgCdTe photodiode arrays.

  7. Nature of the acceptor responsible for p-type conduction in liquid encapsulated Czochralski-grown undoped gallium antimonide

    NASA Astrophysics Data System (ADS)

    Ling, C. C.; Lui, M. K.; Ma, S. K.; Chen, X. D.; Fung, S.; Beling, C. D.

    2004-07-01

    Acceptors in liquid encapsulated Czochralski-grown undoped gallium antimonide (GaSb) were studied by temperature dependent Hall measurement and positron lifetime spectroscopy (PLS). Because of its high concentration and low ionization energy, a level at EV+34meV is found to be the important acceptor responsible for the p-type conduction of the samples. Two different kinds of VGa-related defects (lifetimes of 280ps and 315ps, respectively) having different microstructures were characterized by PLS. By comparing their annealing behaviors and charge state occupancies, the EV+34meV level could not be related to the two VGa-related defects.

  8. Two-dimensional ferromagnet/semiconductor transition metal dichalcogenide contacts: p-type Schottky barrier and spin-injection control

    NASA Astrophysics Data System (ADS)

    Gan, Li-Yong; Zhang, Qingyun; Cheng, Yingchun; Schwingenschlögl, Udo

    2013-12-01

    We study the ferromagnet/semiconductor contacts formed by transition metal dichalcogenide monolayers, focusing on semiconducting MoS2 and WS2 and ferromagnetic VS2. We investigate the degree of p-type doping and demonstrate tuning of the Schottky barrier height by vertical compressive pressure. An analytical model is presented for the barrier heights that accurately describes the numerical findings and is expected to be of general validity for all transition metal dichalcogenide metal/semiconductor contacts. Furthermore, magnetic proximity effects induce a 100% spin polarization at the Fermi level in the semiconductor where the spin splitting increases up to 0.70 eV for increasing pressure.

  9. Development of p-type CCD for the NeXT: the next Japanese x-ray astronomical satellite mission

    NASA Astrophysics Data System (ADS)

    Ozawa, Hideki; Tohiguchi, Masakuni; Matsuura, Daisuke; Miyata, Emi; Tsunemi, Hiroshi; Takagi, Shin-ichiro; Inui, Tatsuya; Tsuru, Takeshi Go; Kamata, Yukiko; Nakaya, Hidehiko; Miyazaki, Satoshi; Miyaguchi, Kazuhisa; Muramatsu, Masaharu; Suzuki, Hisanori

    2006-06-01

    The next Japanese X-ray astronomical satellite mission, NeXT, was proposed to ISAS/JAXA following the Astro-E2 Suzaku satellite which was launched in July 2005. We develop an X-ray CCD camera system, SXI (Soft X-ray Imager), for NeXT. The Hard X-ray Telescope (HXT) onboard NeXT provides imaging capability up to 80 keV, using the multilayer-coated X-ray mirror technology, called "Supermirror", newly developed in Japan. SXI is one of the focal plane detectors of HXT, which covers the soft energy band in the 0.5-12 keV in the baseline and 0.3-25 keV in the goal. We develop p-type CCDs for the baseline of SXI because p-type CCDs have been successfully used for previous X-ray astronomical satellites. We developed a prototype of a p-type CCD for SXI, called "CCD-NeXT1". CCD-NeXT1 is a frame-transfer CCD with two readout nodes. The image area of CCD-NeXT1 consists of 2Kx2K pixels with a pixel size of 12 μm x 12 μm. We evaluated performance of CCD-NeXT1 devices, KG-4 and KG-5. The energy resolution was 141.8+/-0.6 eV full width at half maximum at 5.9 keV, the readout noise was 4.7+/-0.2 e -, the horizontal CTI was < 5.1 x 10 -7, and the vertical CTI was < 2.4 x 10 -7 for KG-5. The performance of KG-4 was more or less the same as that of KG-5. The thickness of the depletion layer was 82+/-7 μm for KG-4 and 76+/-6 μm for KG-5. We conclude that our technology for p-type CCDs is sufficient to satisfy the CCD performance for the baseline of SXI.

  10. Close-geometry efficiency calibration of p-type HPGe detectors with a Cs-134 point source.

    PubMed

    DeFelice, P; Fazio, A; Vidmar, T; Korun, M

    2006-01-01

    When close-geometry detector calibration is required in gamma-ray spectrometry, single-line emitters are usually used in order to avoid true coincidence summing effects. We managed to overcome this limitation by developing a method for the determination of the efficiency of p-type HPGe detectors in close-geometry with a calibrated Cs-134 point source. No separate determination of coincidence summing correction factors is required and a single measurement furnishes the full-energy-peak efficiencies in the 475-1365 keV energy range.

  11. Origins of shallow level and hole mobility in codoped p-type ZnO thin films

    NASA Astrophysics Data System (ADS)

    Ye, H. B.; Kong, J. F.; Shen, W. Z.; Zhao, J. L.; Li, X. M.

    2007-03-01

    A combination study of structural, optical, and electrical properties has been carried out on N-In codoped p-type ZnO thin films for the origins of shallow level and hole mobility. The observed small activation energy of ˜20meV for the hole concentration corresponds well to the results from photoluminescence and conductivity data, revealing the grain boundary trapping nature of the shallow level. The achieved hole mobility is mainly due to the lack of grain boundary barrier effect, and the codoping yielded weak ionized impurity scattering. The authors have also revealed the scattering and conduction mechanisms in these p-ZnO films.

  12. Thin-film transistors based on p-type Cu{sub 2}O thin films produced at room temperature

    SciTech Connect

    Fortunato, Elvira; Figueiredo, Vitor; Barquinha, Pedro; Elamurugu, Elangovan; Goncalves, Goncalo; Martins, Rodrigo; Park, Sang-Hee Ko; Hwang, Chi-Sun

    2010-05-10

    Copper oxide (Cu{sub 2}O) thin films were used to produce bottom gate p-type transparent thin-film transistors (TFTs). Cu{sub 2}O was deposited by reactive rf magnetron sputtering at room temperature and the films exhibit a polycrystalline structure with a strongest orientation along (111) plane. The TFTs exhibit improved electrical performance such as a field-effect mobility of 3.9 cm{sup 2}/V s and an on/off ratio of 2x10{sup 2}.

  13. Impact of interstitial oxygen trapped in silicon during plasma growth of silicon oxy-nitride films for silicon solar cell passivation

    NASA Astrophysics Data System (ADS)

    Saseendran, Sandeep S.; Saravanan, S.; Raval, Mehul C.; Kottantharayil, Anil

    2016-03-01

    Low temperature oxidation of silicon in plasma ambient is a potential candidate for replacing thermally grown SiO2 films for surface passivation of crystalline silicon solar cells. In this work, we report the growth of silicon oxy-nitride (SiOxNy) film in N2O plasma ambient at 380 °C. However, this process results in trapping of interstitial oxygen within silicon. The impact of this trapped interstitial oxygen on the surface passivation quality is investigated. The interstitial oxygen trapped in silicon was seen to decrease for larger SiOxNy film thickness. Effective minority carrier lifetime (τeff) measurements on n-type float zone silicon wafers passivated by SiOxNy/silicon nitride (SiNv:H) stack showed a decrease in τeff from 347 μs to 68 μs, for larger SiOxNy film thickness due to degradation in interface properties. From high frequency capacitance-voltage measurements, it was concluded that the surface passivation quality was governed by the interface parameters (fixed charge density and interface state density). High temperature firing of the SiOxNy/SiNv:H stack resulted in a severe degradation in τeff due to migration of oxygen across the interface into silicon. However, on using the SiOxNy/SiNv:H stack for emitter surface passivation in screen printed p-type Si solar cells, an improvement in short wavelength response was observed in comparison to the passivation by SiNv:H alone, indicating an improvement in emitter surface passivation quality.

  14. Electrical transport in transverse direction through silicon carbon alloy multilayers containing regular size silicon quantum dots

    NASA Astrophysics Data System (ADS)

    Mandal, Aparajita; Kole, Arindam; Dasgupta, Arup; Chaudhuri, Partha

    2016-11-01

    Electrical transport in the transverse direction has been studied through a series of hydrogenated silicon carbon alloy multilayers (SiC-MLs) deposited by plasma enhanced chemical vapor deposition method. Each SiC-ML consists of 30 cycles of the alternating layers of a nearly amorphous silicon carbide (a-SiC:H) and a microcrystalline silicon carbide (μc-SiC:H) that contains high density of silicon quantum dots (Si-QDs). A detailed investigation by cross sectional TEM reveals preferential growth of densely packed Si-QDs of regular sizes ∼4.8 nm in diameter in a vertically aligned columnar structure within the SiC-ML. More than six orders of magnitude increase in transverse current through the SiC-ML structure were observed for decrease in the a-SiC:H layer thickness from 13 nm to 2 nm. The electrical transport mechanism was established to be a combination of grain boundary or band tail hopping and Frenkel-Poole (F-P) type conduction depending on the temperature and externally applied voltage ranges. Evaluation of trap concentration within the multilayer structures from the fitted room temperature current voltage characteristics by F-P function shows reduction up-to two orders of magnitude indicating an improvement in the short range order in the a-SiC:H matrix for decrease in the thickness of a-SiC:H layer.

  15. Silicon heterojunction solar cell with passivated hole selective MoOx contact

    NASA Astrophysics Data System (ADS)

    Battaglia, Corsin; de Nicolás, Silvia Martín; De Wolf, Stefaan; Yin, Xingtian; Zheng, Maxwell; Ballif, Christophe; Javey, Ali

    2014-03-01

    We explore substoichiometric molybdenum trioxide (MoOx, x < 3) as a dopant-free, hole-selective contact for silicon solar cells. Using an intrinsic hydrogenated amorphous silicon passivation layer between the oxide and the silicon absorber, we demonstrate a high open-circuit voltage of 711 mV and power conversion efficiency of 18.8%. Due to the wide band gap of MoOx, we observe a substantial gain in photocurrent of 1.9 mA/cm2 in the ultraviolet and visible part of the solar spectrum, when compared to a p-type amorphous silicon emitter of a traditional silicon heterojunction cell. Our results emphasize the strong potential for oxides as carrier selective heterojunction partners to inorganic semiconductors.

  16. Glass-silicon column

    DOEpatents

    Yu, Conrad M.

    2003-12-30

    A glass-silicon column that can operate in temperature variations between room temperature and about 450.degree. C. The glass-silicon column includes large area glass, such as a thin Corning 7740 boron-silicate glass bonded to a silicon wafer, with an electrode embedded in or mounted on glass of the column, and with a self alignment silicon post/glass hole structure. The glass/silicon components are bonded, for example be anodic bonding. In one embodiment, the column includes two outer layers of silicon each bonded to an inner layer of glass, with an electrode imbedded between the layers of glass, and with at least one self alignment hole and post arrangement. The electrode functions as a column heater, and one glass/silicon component is provided with a number of flow channels adjacent the bonded surfaces.

  17. Porous silicon gettering

    SciTech Connect

    Tsuo, Y.S.; Menna, P.; Al-Jassim, M.

    1995-08-01

    We have studied a novel extrinsic gettering method that utilizes the very large surface areas, produced by porous silicon etch on both front and back surfaces of the silicon wafer, as gettering sites. In this method, a simple and low-cost chemical etching is used to generate the porous silicon layers. Then, a high-flux solar furnace (HFSF) is used to provide high-temperature annealing and the required injection of silicon interstitials. The gettering sites, along with the gettered impurities, can be easily removed at the end the process. The porous silicon removal process consists of oxidizing the porous silicon near the end the gettering process followed by sample immersion in HF acid. Each porous silicon gettering process removes up to about 10 {mu}m of wafer thickness. This gettering process can be repeated so that the desired purity level is obtained.

  18. Study of the crystal structure of silicon nanoislands on sapphire

    SciTech Connect

    Krivulin, N. O. Pirogov, A. V.; Pavlov, D. A.; Bobrov, A. I.

    2015-02-15

    The results of studies of the crystal structure of silicon nanoislands on sapphire are reported. It is shown that the principal defects in silicon nanoislands on sapphire are twinning defects. As a result of the formation of such defects, different crystallographic orientations are formed in silicon nanoislands on sapphire. In the initial stages of the molecular-beam epitaxy of silicon on sapphire, there are two basic orientations: the (001) orientation parallel to the surface and the (001) orientation at an angle of 70° to the surface.

  19. A conserved asparagine in a P-type proton pump is required for efficient gating of protons.

    PubMed

    Ekberg, Kira; Wielandt, Alex G; Buch-Pedersen, Morten J; Palmgren, Michael G

    2013-04-05

    The minimal proton pumping machinery of the Arabidopsis thaliana P-type plasma membrane H(+)-ATPase isoform 2 (AHA2) consists of an aspartate residue serving as key proton donor/acceptor (Asp-684) and an arginine residue controlling the pKa of the aspartate. However, other important aspects of the proton transport mechanism such as gating, and the ability to occlude protons, are still unclear. An asparagine residue (Asn-106) in transmembrane segment 2 of AHA2 is conserved in all P-type plasma membrane H(+)-ATPases. In the crystal structure of the plant plasma membrane H(+)-ATPase, this residue is located in the putative ligand entrance pathway, in close proximity to the central proton donor/acceptor Asp-684. Substitution of Asn-106 resulted in mutant enzymes with significantly reduced ability to transport protons against a membrane potential. Sensitivity toward orthovanadate was increased when Asn-106 was substituted with an aspartate residue, but decreased in mutants with alanine, lysine, glutamine, or threonine replacement of Asn-106. The apparent proton affinity was decreased for all mutants, most likely due to a perturbation of the local environment of Asp-684. Altogether, our results demonstrate that Asn-106 is important for closure of the proton entrance pathway prior to proton translocation across the membrane.

  20. Magnetism in the p-type Monolayer II-VI semiconductors SrS and SrSe

    PubMed Central

    Lin, Heng-Fu; Lau, Woon-Ming; Zhao, Jijun

    2017-01-01

    Using density functional theory calculations, we study the electronic and magnetic properties of the p-type monolayer II-VI semiconductors SrX (X = S,Se). The pristine SrS and SrSe monolayers are large band gap semiconductor with a very flat band in the top valence band. Upon injecting hole uniformly, ferromagnetism emerges in those system in a large range of hole density. By varying hole density, the systems also show complicated phases transition among nonmagnetic semiconductor, half metal, magnetic semiconductor, and nonmagnetic metal. Furthermore, after introducing p-type dopants in SrS and SrSe via substitutionary inserting P (or As) dopants at the S (or Se) sites, local magnetic moments are formed around the substitutional sites. The local magnetic moments are stable with the ferromagnetic order with appreciable Curie temperature. The ferromagnetism originates from the instability of the electronic states in SrS and SrSe with the large density of states at the valence band edge, which demonstrates a useful strategy for realizing the ferromagnetism in the two dimensional semiconductors. PMID:28378761

  1. Inhibition of acetylcholine release from mouse motor nerve by a P-type calcium channel blocker, omega-agatoxin IVA.

    PubMed Central

    Hong, S J; Chang, C C

    1995-01-01

    1. The effects were studied of the central neurone P-type Ca2+ channel blockers, omega-agatoxin IVA, omega-conotoxin MVIIC (polypeptide toxins) and synthetic funnel-web spider polyamine toxin on acetylcholine release from mouse motor nerve. 2. omega-Agatoxin IVA decreased the quantal content of endplate potentials and blocked synaptic transmission in the nanomolar range in a reversible manner, whereas the other toxins depressed transmission in the hundred micromolar range. 3. The polyamine toxin, but not the polypeptide toxins, decreased the amplitude of the miniature endplate potential. The increase in the frequency of miniature endplate potentials evoked by high [K+], but not that evoked by alpha-latrotoxin, was effectively antagonized by omega-agatoxin IVA. 4. In the presence of omega-agatoxin IVA, high frequency nerve stimulation produced facilitation of endplate currents and tetanic contractions. 5. The results suggest that, under physiological conditions, the Ca2+ necessary for nerve action potential-evoked acetylcholine release is translocated via a subtype of the P-type Ca2+ channel sensitive to omega-agatoxin IVA. PMID:7714822

  2. Presence of Na+-stimulated P-type ATPase in the membrane of a facultatively anaerobic alkaliphile, Exiguobacterium aurantiacum.

    PubMed

    Koyama, N

    1999-07-01

    It was found that a facultatively anaerobic alkaliphile, Exiguobacterium aurantiacum, possesses a membrane-bound ATPase, which was activated specifically by Na+. The Na+-stimulated ATPase activity reached a maximum value at 200 mM NaCl. In the presence of 200 mM NaCl, the activity was drastically reduced by vanadate, a potent inhibitor of P-type ATPase, with a half-maximal inhibition at 1 microM. Incubation of the membranes with [gamma-32P]ATP followed by acidic lithium dodecyl sulfate-polyacrylamide gel electrophoresis demonstrated the existence of two phosphorylated intermediates with apparent molecular masses of 60 and 100 kDa. Only phosphorylation of the 100-kDa polypeptide was inhibited by vanadate. The membrane extract containing Na+-stimulated ATPase, when reconstituted into soybean phospholipid vesicles, exhibited 22Na+ transport by the addition of ATP, which was inhibited by vanadate and gramicidin. It is likely that the Na+-stimulated ATPase belongs to P-type and is involved in Na+ transport.

  3. Field-Effect Modulation of Ambipolar Doping and Domain Wall Band Alignment in P-type Vanadium Dioxide Nanowires

    NASA Astrophysics Data System (ADS)

    Hou, Yasen; Peng, Xingyue; Yang, Yiming; Yu, Dong

    The sub-picosecond metal-insulator phase transition in vanadium dioxide (VO2) has attracted extensive attention with potential applications in ultrafast Mott transistors. However, the development of VO2-based transistors lags behind, owing to the lack of an efficient and hysteresis-free electrostatic doping control. Here we report the first synthesis of p-type single crystalline VO2nanowires via catalyst-free chemical vapor deposition. The p-type doping was unambiguously confirmed by both solid and electrochemical gating methods, and further evidenced by the scanning photocurrent microscopic measurements. Interestingly, we observed that the photocurrent spot polarity at the metal-insulator domain walls was reversibly switched by electrochemical gating, which indicates a band bending flipping. Furthermore, we eliminated the common hysteresis in gate sweep and greatly shortened the transistor response time via a hybrid gating method, which combines the merits of liquid ionic and solid gating. The capability of efficient field effect modulation of ambipolar conduction and band alignment offers new opportunities on understanding the phase transition mechanism and enables novel electronic applications based on VO2.

  4. Improved p-type conductivity in Al-rich AlGaN using multidimensional Mg-doped superlattices

    PubMed Central

    Zheng, T. C.; Lin, W.; Liu, R.; Cai, D. J.; Li, J. C.; Li, S. P.; Kang, J. Y.

    2016-01-01

    A novel multidimensional Mg-doped superlattice (SL) is proposed to enhance vertical hole conductivity in conventional Mg-doped AlGaN SL which generally suffers from large potential barrier for holes. Electronic structure calculations within the first-principle theoretical framework indicate that the densities of states (DOS) of the valence band nearby the Fermi level are more delocalized along the c-axis than that in conventional SL, and the potential barrier significantly decreases. Hole concentration is greatly enhanced in the barrier of multidimensional SL. Detailed comparisons of partial charges and decomposed DOS reveal that the improvement of vertical conductance may be ascribed to the stronger pz hybridization between Mg and N. Based on the theoretical analysis, highly conductive p-type multidimensional Al0.63Ga0.37N/Al0.51Ga0.49N SLs are grown with identified steps via metalorganic vapor-phase epitaxy. The hole concentration reaches up to 3.5 × 1018 cm−3, while the corresponding resistivity reduces to 0.7 Ω cm at room temperature, which is tens times improvement in conductivity compared with that of conventional SLs. High hole concentration can be maintained even at 100 K. High p-type conductivity in Al-rich structural material is an important step for the future design of superior AlGaN-based deep ultraviolet devices. PMID:26906334

  5. The Synthesis and Thermoelectric Properties of p-Type Li1- x NbO2-Based Compounds

    NASA Astrophysics Data System (ADS)

    Rahman, Jamil Ur; Meang, Eun-Ji; Van Nguyen, Du; Seo, Won-Seon; Hussain, Ali; Kim, Myong Ho; Lee, Soonil

    2017-03-01

    We investigated the thermoelectric (TE) properties of a p-type oxide material (Li1- x NbO2, with x = 0-0.6). The composition was synthesized via a solid-state reaction method under a reducing atmosphere. The charge transport properties were determined through the electrical conductivity and Seebeck coefficient measurements. The electrical conductivity was non-monotonically varied with x value and showed metallic behavior with increased temperature and above 650 K temperature independent behavior dominated by extrinsic conduction. On the other hand, the Seebeck coefficient was increased with an increase in the temperature, and decreased gradually with an increase in the Li vacancy concentration by both synthesis and gradual phase transition to a Li-rich Li3NbO4 phase with temperature and appeared as an n-type TE at x = 0.6 under high temperatures, which was attributed to an Nb substitution into the Li site. The thermal conductivity was monotonically reduced with the increase in temperature due to the cation disorder defects and second phases. The Li vacancy induced Li1- x NbO2-based compounds under low oxygen partial pressure show promise as a candidate p-type material for thermoelectric applications, particularly for co-processing with n-type oxide thermoelectric materials fabricated under conditions of low oxygen partial pressure.

  6. New p-type absorber films formed by interfacial diffusion in chemically deposited metal chalcogenide multilayer films

    SciTech Connect

    Nair, P.K.; Nair, M.T.S.; Hu, H.; Huang, L.; Zingaro, R.A.; Meyers, E.A.

    1995-12-31

    The authors report on new p-type ternary metal chalcogenide absorber films for possible solar energy applications. The films are formed by interfacial diffusion in chemically deposited multilayer films: CuS films (0.15--0.6 {micro}m) deposited on ZnS, PbS or Bi{sub 2}S{sub 3} films ({approx} 0.1 {micro}m). The diffusion takes place during annealing at temperatures above 150 C and is shown in the XPS depth profile spectra of the annealed samples: metal atoms (Zn, Pb or Bi) of the underlying substrate films are detected at the surface layers after the annealing. The peculiarity of the multilayer films is that they show almost constant sheet resistance upon further annealing until 350 C. The sheet resistances are in the range of 20--100 {Omega} suggesting conductivities (p-type) of up to 400 {Omega}{sup {minus}1}. In the case of CuS on Bi{sub 2}S{sub 3} films, the formation of a compound, Cu{sub 3}BiS{sub 3}, is clearly detected. These have applications for solar cells.

  7. Structural studies of P-type ATPase–ligand complexes using an X-ray free-electron laser

    DOE PAGES

    Bublitz, Maike; Nass, Karol; Drachmann, Nikolaj D.; ...

    2015-06-11

    Membrane proteins are key players in biological systems, mediating signalling events and the specific transport ofe.g.ions and metabolites. Consequently, membrane proteins are targeted by a large number of currently approved drugs. Understanding their functions and molecular mechanisms is greatly dependent on structural information, not least on complexes with functionally or medically important ligands. Structure determination, however, is hampered by the difficulty of obtaining well diffracting, macroscopic crystals. Here, the feasibility of X-ray free-electron-laser-based serial femtosecond crystallography (SFX) for the structure determination of membrane protein–ligand complexes using microcrystals of various native-source and recombinant P-type ATPase complexes is demonstrated. The data revealmore » the binding sites of a variety of ligands, including lipids and inhibitors such as the hallmark P-type ATPase inhibitor orthovanadate. By analyzing the resolution dependence of ligand densities and overall model qualities, SFX data quality metrics as well as suitable refinement procedures are discussed. Even at relatively low resolution and multiplicity, the identification of ligands can be demonstrated. This makes SFX a useful tool for ligand screening and thus for unravelling the molecular mechanisms of biologically active proteins.« less

  8. Structural studies of P-type ATPase–ligand complexes using an X-ray free-electron laser

    SciTech Connect

    Bublitz, Maike; Nass, Karol; Drachmann, Nikolaj D.; Markvardsen, Anders J.; Gutmann, Matthias J.; Barends, Thomas R. M.; Mattle, Daniel; Shoeman, Robert L.; Doak, R. Bruce; Boutet, Sébastien; Messerschmidt, Marc; Seibert, Marvin M.; Williams, Garth J.; Foucar, Lutz; Reinhard, Linda; Sitsel, Oleg; Gregersen, Jonas L.; Clausen, Johannes D.; Boesen, Thomas; Gotfryd, Kamil; Wang, Kai -Tuo; Olesen, Claus; Møller, Jesper V.; Nissen, Poul; Schlichting, Ilme

    2015-06-11

    Membrane proteins are key players in biological systems, mediating signalling events and the specific transport ofe.g.ions and metabolites. Consequently, membrane proteins are targeted by a large number of currently approved drugs. Understanding their functions and molecular mechanisms is greatly dependent on structural information, not least on complexes with functionally or medically important ligands. Structure determination, however, is hampered by the difficulty of obtaining well diffracting, macroscopic crystals. Here, the feasibility of X-ray free-electron-laser-based serial femtosecond crystallography (SFX) for the structure determination of membrane protein–ligand complexes using microcrystals of various native-source and recombinant P-type ATPase complexes is demonstrated. The data reveal the binding sites of a variety of ligands, including lipids and inhibitors such as the hallmark P-type ATPase inhibitor orthovanadate. By analyzing the resolution dependence of ligand densities and overall model qualities, SFX data quality metrics as well as suitable refinement procedures are discussed. Even at relatively low resolution and multiplicity, the identification of ligands can be demonstrated. This makes SFX a useful tool for ligand screening and thus for unravelling the molecular mechanisms of biologically active proteins.

  9. Search for Pauli exclusion principle violating atomic transitions and electron decay with a p-type point contact germanium detector

    SciTech Connect

    Abgrall, N.; Arnquist, I. J.; Avignone, F. T.; Barabash, A. S.; Bertrand, F. E.; Bradley, A. W.; Brudanin, V.; Busch, M.; Buuck, M.; Caldwell, A. S.; Chan, Y. -D.; Christofferson, C. D.; Chu, Pinghan -H.; Cuesta, C.; Detwiler, J. A.; Dunagan, C.; Efremenko, Yu.; Ejiri, H.; Elliott, Steven Ray; Finnerty, P. S.; Galindo-Uribarri, A.; Gilliss, T.; Giovanetti, Graham K.; Goett, John Jerome; Green, M. P.; Gruszko, J.; Guinn, I. S.; Guiseppe, V. E.; Henning, R.; Hoppe, E. W.; Howard, S.; Howe, M. A.; Jasinski, B. R.; Keeter, K. J.; Kidd, M. F.; Konovalov, S. I.; Kouzes, R. T.; LaFerriere, B. D.; Leon, J.; MacMullin, J.; Martin, R. D.; Massarczyk, R.; Meijer, S. J.; Mertens, S.; Orrell, J. L.; O’Shaughnessy, C.; Poon, A. W. P.; Radford, D. C.; Rager, J.; Rielage, Keith Robert; Robertson, R. G. H.; Romero-Romero, E.; Shanks, B.; Shirchenko, M.; Suriano, A. M.; Tedeschi, D.; Trimble, J. E.; Varner, R. L.; Vasilyev, S.; Vetter, K.; Vorren, K.; White, B. R.; Wilkerson, J. F.; Wiseman, C.; Xu, W.; Yakushev, E.; Yu, C. -H.; Yumatov, V.; Zhitnikov, I.

    2016-11-11

    Here, a search for Pauli-exclusion-principle-violating Kα electron transitions was performed using 89.5 kg-d of data collected with a p-type point contact high-purity germanium detector operated at the Kimballton Underground Research Facility. A lower limit on the transition lifetime of 5.8×1030 s at 90% C.L. was set by looking for a peak at 10.6 keV resulting from the X-ray and Auger electrons present following the transition. A similar analysis was done to look for the decay of atomic K-shell electrons into neutrinos, resulting in a lower limit of 6.8×1030 s at 90% C.L. Finally, it is estimated that the Majorana Demonstrator, a 44 kg array of p-type point contact detectors that will search for the neutrinoless double-beta decay of 76Ge, could improve upon these exclusion limits by an order of magnitude after three years of operation.

  10. Characterization of a heavy metal translocating P-type ATPase gene from an environmental heavy metal resistance Enterobacter sp. isolate.

    PubMed

    Chien, Chih-Ching; Huang, Chia-Hsuan; Lin, Yi-Wei

    2013-03-01

    Heavy metals are common contaminants found in polluted areas. We have identified a heavy metal translocating P-type ATPase gene (hmtp) via fosmid library and in vitro transposon mutagenesis from an Enterobacter sp. isolate. This gene is believed to participate in the bacterium's heavy metal resistance traits. The complete gene was identified, cloned, and expressed in a suitable Escherichia coli host cell. E. coli W3110, RW3110 (zntA::Km), GG48 (ΔzitB::Cm zntA::Km), and GG51 (ΔzitB::Cm) were used to study the possible effects of this gene for heavy metal (cadmium and zinc in particular) resistance. Among the E. coli strains tested, RW3110 and GG48 showed more sensitivity to cadmium and zinc compared to the wild-type E. coli W3110 and strain GG51. Therefore, strains RW3110 and GG48 were chosen for the reference hosts for further evaluation of the gene's effect. The results showed that expression of this heavy metal translocating P-type ATPase gene could increase the ability for zinc and cadmium resistance in the tested microorganisms.

  11. The synthesis and characterization of Ag-N dual-doped p-type ZnO: experiment and theory.

    PubMed

    Duan, Li; Wang, Pei; Yu, Xiaochen; Han, Xiao; Chen, Yongnan; Zhao, Peng; Li, Donglin; Yao, Ran

    2014-03-07

    Ag-N dual-doped ZnO films have been fabricated by a chemical bath deposition method. The p-type conductivity of the dual-doped ZnO:(Ag, N) is stable over a long period of time, and the hole concentration in the ZnO:(Ag, N) is much higher than that in mono-doped ZnO:Ag or ZnO:N. We found that this is because AgZn-NO complex acceptors can be formed in ZnO:(Ag, N). First-principles calculations show that the complex acceptors generate a fully occupied band above the valance band maximum, so the acceptor levels become shallower and the hole concentration is increased. Furthermore, the binding energy of the Ag-N complex in ZnO is negative, so ZnO:(Ag, N) can be stable. These results indicate that the Ag-N dual-doping may be expected to be a potential route to achieving high-quality p-type ZnO for use in a variety of devices.

  12. Binary Oxide p-n Heterojunction Piezoelectric Nanogenerators with an Electrochemically Deposited High p-Type Cu2O Layer.

    PubMed

    Baek, Seung Ki; Kwak, Sung Soo; Kim, Joo Sung; Kim, Sang Woo; Cho, Hyung Koun

    2016-08-31

    The high performance of ZnO-based piezoelectric nanogenerators (NGs) has been limited due to the potential screening from intrinsic electron carriers in ZnO. We have demonstrated a novel approach to greatly improve piezoelectric power generation by electrodepositing a high-quality p-type Cu2O layer between the piezoelectric semiconducting film and the metal electrode. The p-n heterojunction using only oxides suppresses the screening effect by forming an intrinsic depletion region, and thus sufficiently enhances the piezoelectric potential, compared to the pristine ZnO piezoelectric NG. Interestingly, a Sb-doped Cu2O layer has high mobility and low surface trap states. Thus, this doped layer is an attractive p-type material to significantly improve piezoelectric performance. Our results revealed that p-n junction NGs consisting of Au/ZnO/Cu2O/indium tin oxide with a Cu2O:Sb (cuprous oxide with a small amount of antimony) layer of sufficient thickness (3 μm) exhibit an extraordinarily high piezoelectric potential of 0.9 V and a maximum output current density of 3.1 μA/cm(2).

  13. Van der Pauw Hall Measurement on Intended Doped ZnO Films for p-Type Conductivity

    NASA Astrophysics Data System (ADS)

    Guo, Yang; Liu, Yac-Ping; Li, Jun-Qiang; Zhang, Sheng-Li; Mei, Zeng-Xia; Du, Xiao-Long

    2010-06-01

    A Van der Pauw Hall measurement is performed on the intended doped ZnO films (Na doped ZnO) grown by using the molecular beam epitaxial method. All as-grown samples show n-type conductivity, whereas the annealed samples (annealing temperature 900° C) show ambiguous carrier conductivity type (n- and p-type) in the automatic Van der Pauw Hall measurement. A similar result has been observed in Li doped ZnO and in as-doped ZnO films by other groups before. However, by tracing the Hall voltage in the Van der Pauw Hall measurement, it is found that this alternative appearance of both n- and p-type conductivity is not intrinsic behavior of the intended doped ZnO films, but is due to the persistent photoconductivity effect in ZnO. The persistent photoconductivity effect would strongly affect the accurate determination of the carrier conductivity type of a highly resistive intended doped ZnO sample.

  14. The Synthesis and Thermoelectric Properties of p-Type Li1-x NbO2-Based Compounds

    NASA Astrophysics Data System (ADS)

    Rahman, Jamil Ur; Meang, Eun-Ji; Van Nguyen, Du; Seo, Won-Seon; Hussain, Ali; Kim, Myong Ho; Lee, Soonil

    2017-01-01

    We investigated the thermoelectric (TE) properties of a p-type oxide material (Li1-x NbO2, with x = 0-0.6). The composition was synthesized via a solid-state reaction method under a reducing atmosphere. The charge transport properties were determined through the electrical conductivity and Seebeck coefficient measurements. The electrical conductivity was non-monotonically varied with x value and showed metallic behavior with increased temperature and above 650 K temperature independent behavior dominated by extrinsic conduction. On the other hand, the Seebeck coefficient was increased with an increase in the temperature, and decreased gradually with an increase in the Li vacancy concentration by both synthesis and gradual phase transition to a Li-rich Li3NbO4 phase with temperature and appeared as an n-type TE at x = 0.6 under high temperatures, which was attributed to an Nb substitution into the Li site. The thermal conductivity was monotonically reduced with the increase in temperature due to the cation disorder defects and second phases. The Li vacancy induced Li1-x NbO2-based compounds under low oxygen partial pressure show promise as a candidate p-type material for thermoelectric applications, particularly for co-processing with n-type oxide thermoelectric materials fabricated under conditions of low oxygen partial pressure.

  15. Boron liquid solution deposited by spray method for p-type emitter formation in crystalline Si solar cells

    NASA Astrophysics Data System (ADS)

    Panek, Piotr; Swatowska, Barbara; Dawidowski, Wojciech; Juel, Mari; Zieba, Paweł

    2016-12-01

    This paper reports the fabrication of n-type crystalline Si based solar cell using boron liquid solution (BLS) deposited by spray method for p-type emitter formation. The X-ray photoelectron spectroscopy (XPS) was used for the analysis of surface composition and electronic states of elements at the glass layer of dopant (GLD) obtained from BLS. The investigation of the borosilicate glass layer (BSG) created on a base of GLD during diffusion process were carried out by transmission electron microscopy (TEM). The diffusion profiles were determined by secondary ion mass spectrometry (SIMS) and electrochemical capacitance-voltage (EC-V) techniques, whereas the solar cells were characterized by the light current-voltage (I-V) and spectral measurements. The influence of a doping process on a minority carrier lifetime of the Si wafers was detected by quasi-steady-state photoconductance technique. Application of the elaborated BSL allowed to obtain the p-type Si emitters from BSG layer which exhibits unproblematic etching behaviour after diffusion process and final fabrication of the solar cells with the fill factor of 74% and photoconversion efficiency of 13.04 %. The elaborated BLS is a source which offers an attractive practicable alternative to form emitters on the n-type Si substrate.

  16. RAPID COMMUNICATION: Formation of p-type CdS thin films by laser-stimulated copper diffusion

    NASA Astrophysics Data System (ADS)

    Dzhafarov, T. D.; Altunbas, M.; Kopya, A. I.; Novruzov, V.; Bacaksiz, E.

    1999-12-01

    A new fabrication technique of p-type CdS thin films by He-Ne laser illumination of bilayer Cu-nCdS structures at room temperature was investigated. The n-type CdS films were obtained by vacuum evaporation in a quasi-closed volume. X-ray diffraction was used to provide crystalline structure and composition data of CdS films and Cu-CdS structures. The band gap of CdS films was estimated from the optical transmission spectra. The hot probe and Hall effect studies were used for the determination of conductivity type and concentration of charge carriers in films. The formation of a p-n homojunction in CdS films or conversion of the film all over to the p-type, depending on the duration of laser illumination, was shown by I-V characteristics, the photovoltaic, the hot probe and Hall effect measurements. Analysis of concentration distributions of Cu in CdS films, arising as a result of laser-accelerated diffusion, by energy dispersive x-ray spectroscopy gave the effective diffusion coefficient of copper, D = 8 × 10-12 cm2 s-1 at T = 25 °C.

  17. Perovskite LaRhO{sub 3} as a p-type active layer in oxide photovoltaics

    SciTech Connect

    Nakamura, Masao Krockenberger, Yoshiharu; Fujioka, Jun; Kawasaki, Masashi; Tokura, Yoshinori

    2015-02-16

    Perovskite-type transition-metal oxides have a wide variety of physical properties and triggered intensive research on functional devices in the form of heteroepitaxial junctions. However, there is a missing component that is a p-type conventional band semiconductor. LaRhO{sub 3} (LRO) is one of very few promising candidates having its bandgap between filled t{sub 2g} and empty e{sub g} of Rh in low-spin state, but there has been no report on the synthesis of large-size single crystals or thin films. Here, we report on the junction properties of single-crystalline thin films of LRO grown on (110) oriented Nb-doped SrTiO{sub 3} substrates. The external quantum efficiency of the photo-electron conversion exceeds 1% in the visible-light region due to the wide depletion layer and long diffusion length of minority carriers in LRO. Clear indication of p-type band semiconducting character in a perovskite oxide of LRO will pave a way to explore oxide electronics of perovskite heterostructures.

  18. Fundamental piezo-Hall coefficients of single crystal p-type 3C-SiC for arbitrary crystallographic orientation

    NASA Astrophysics Data System (ADS)

    Qamar, Afzaal; Dao, Dzung Viet; Phan, Hoang-Phuong; Dinh, Toan; Dimitrijev, Sima

    2016-08-01

    Piezo-Hall effect in a single crystal p-type 3C-SiC, grown by LPCVD process, has been characterized for various crystallographic orientations. The quantified values of the piezo-Hall effect in heavily doped p-type 3C-SiC(100) and 3C-SiC(111) for different crystallographic orientations were used to obtain the fundamental piezo-Hall coefficients, P 12 = ( 5.3 ± 0.4 ) × 10 - 11 Pa - 1 , P 11 = ( - 2.6 ± 0.6 ) × 10 - 11 Pa - 1 , and P 44 = ( 11.42 ± 0.6 ) × 10 - 11 Pa - 1 . Unlike the piezoresistive effect, the piezo-Hall effect for (100) and (111) planes is found to be independent of the angle of rotation of the device within the crystal plane. The values of fundamental piezo-Hall coefficients obtained in this study can be used to predict the piezo-Hall coefficients in any crystal orientation which is very important for designing of 3C-SiC Hall sensors to minimize the piezo-Hall effect for stable magnetic field sensitivity.

  19. Structural studies of P-type ATPase–ligand complexes using an X-ray free-electron laser

    PubMed Central

    Bublitz, Maike; Nass, Karol; Drachmann, Nikolaj D.; Markvardsen, Anders J.; Gutmann, Matthias J.; Barends, Thomas R. M.; Mattle, Daniel; Shoeman, Robert L.; Doak, R. Bruce; Boutet, Sébastien; Messerschmidt, Marc; Seibert, Marvin M.; Williams, Garth J.; Foucar, Lutz; Reinhard, Linda; Sitsel, Oleg; Gregersen, Jonas L.; Clausen, Johannes D.; Boesen, Thomas; Gotfryd, Kamil; Wang, Kai-Tuo; Olesen, Claus; Møller, Jesper V.; Nissen, Poul; Schlichting, Ilme

    2015-01-01

    Membrane proteins are key players in biological systems, mediating signalling events and the specific transport of e.g. ions and metabolites. Consequently, membrane proteins are targeted by a large number of currently approved drugs. Understanding their functions and molecular mechanisms is greatly dependent on structural information, not least on complexes with functionally or medically important ligands. Structure determination, however, is hampered by the difficulty of obtaining well diffracting, macroscopic crystals. Here, the feasibility of X-ray free-electron-laser-based serial femtosecond crystallography (SFX) for the structure determination of membrane protein–ligand complexes using microcrystals of various native-source and recombinant P-type ATPase complexes is demonstrated. The data reveal the binding sites of a variety of ligands, including lipids and inhibitors such as the hallmark P-type ATPase inhibitor orthovanadate. By analyzing the resolution dependence of ligand densities and overall model qualities, SFX data quality metrics as well as suitable refinement procedures are discussed. Even at relatively low resolution and multiplicity, the identification of ligands can be demonstrated. This makes SFX a useful tool for ligand screening and thus for unravelling the molecular mechanisms of biologically active proteins. PMID:26175901

  20. Novel p-Type Conductive Semiconductor Nanocrystalline Film as the Back Electrode for High-Performance Thin Film Solar Cells.

    PubMed

    Zhang, Ming-Jian; Lin, Qinxian; Yang, Xiaoyang; Mei, Zongwei; Liang, Jun; Lin, Yuan; Pan, Feng

    2016-02-10

    Thin film solar cells, due to the low cost, high efficiency, long-term stability, and consumer applications, have been widely applied for harvesting green energy. All of these thin film solar cells generally adopt various metal thin films as the back electrode, like Mo, Au, Ni, Ag, Al, graphite, and so forth. When they contact with p-type layer, it always produces a Schottky contact with a high contact potential barrier, which greatly affects the cell performance. In this work, we report for the first time to find an appropriate p-type conductive semiconductor film, digenite Cu9S5 nanocrystalline film, as the back electrode for CdTe solar cells as the model device. Its low sheet resistance (16.6 Ω/sq) could compare to that of the commercial TCO films (6-30 Ω/sq), like FTO, ITO, and AZO. Different from the traditonal metal back electrode, it produces a successive gradient-doping region by the controllable Cu diffusion, which greatly reduces the contact potential barrier. Remarkably, it achieved a comparable power conversion efficiency (PCE, 11.3%) with the traditional metal back electrode (Cu/Au thin films, 11.4%) in CdTe cells and a higher PCE (13.8%) with the help of the Au assistant film. We believe it could also act as the back electrode for other thin film solar cells (α-Si, CuInS2, CIGSe, CZTS, etc.), for their performance improvement.

  1. High performance printed N and P-type OTFTs enabling digital and analog complementary circuits on flexible plastic substrate

    NASA Astrophysics Data System (ADS)

    Jacob, S.; Abdinia, S.; Benwadih, M.; Bablet, J.; Chartier, I.; Gwoziecki, R.; Cantatore, E.; van Roermund, A. H. M.; Maddiona, L.; Tramontana, F.; Maiellaro, G.; Mariucci, L.; Rapisarda, M.; Palmisano, G.; Coppard, R.

    2013-06-01

    This paper presents a printed organic complementary technology on flexible plastic substrate with high performance N and P-type Organic Thin Film Transistors (OTFTs), based on small-molecule organic semiconductors in solution. Challenges related to the integration of both OTFT types in a common complementary flow are addressed, showing the importance of surface treatments. Stability on single devices and on an elementary complementary digital circuit (ring oscillator) is studied, demonstrating that a robust and reliable flow with high electrical performances can be established for printed organic devices. These devices are used to manufacture several analog and digital building blocks. The design is carried out using a model specifically developed for this technology, and taking into account the parametric variability. High-frequency measurements of printed envelope detectors show improved speed performance, resulting from the high mobility of the OTFTs. In addition, a compact dynamic flip-flop and a low-offset comparator are demonstrated, thanks to availability of both n-type and p-type OTFTs in the technology. Measurement results are in good agreement with the simulations. The circuits presented establish a complete library of building blocks for the realization of a printed RFID tag.

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

    SciTech Connect

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

    2006-09-01

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

  3. Search for Pauli exclusion principle violating atomic transitions and electron decay with a p-type point contact germanium detector

    DOE PAGES

    Abgrall, N.; Arnquist, I. J.; Avignone, F. T.; ...

    2016-11-11

    Here, a search for Pauli-exclusion-principle-violating Kα electron transitions was performed using 89.5 kg-d of data collected with a p-type point contact high-purity germanium detector operated at the Kimballton Underground Research Facility. A lower limit on the transition lifetime of 5.8×1030 s at 90% C.L. was set by looking for a peak at 10.6 keV resulting from the X-ray and Auger electrons present following the transition. A similar analysis was done to look for the decay of atomic K-shell electrons into neutrinos, resulting in a lower limit of 6.8×1030 s at 90% C.L. Finally, it is estimated that the Majorana Demonstrator,more » a 44 kg array of p-type point contact detectors that will search for the neutrinoless double-beta decay of 76Ge, could improve upon these exclusion limits by an order of magnitude after three years of operation.« less

  4. Comparative studies on p-type CuI grown on glass and copper substrate by SILAR method

    NASA Astrophysics Data System (ADS)

    Dhere, Sunetra L.; Latthe, Sanjay S.; Kappenstein, Charles; Mukherjee, S. K.; Rao, A. Venkateswara

    2010-04-01

    Depending upon the method of synthesis and the nature of substrate surface, there is variation in the physico-chemical properties of the material. Cuprous iodide films are deposited at room temperature on the glass and copper substrates by a simple SILAR method and the obtained results are compared. The p-type material with optical band gap 2.88 eV is found to be possessing face-centered cubic crystal structure with lattice parameter 6.134 Å. We observed irregular particles for the CuI film on the glass substrate while patterned arrays of micro-rods with cabbage like tips on copper substrate, for the same preparative conditions. Also, the material deposited on copper is showing superhydrophobic nature (contact angle ˜156°) while that on glass it is hydrophilic (contact angle ˜88°). We have characterized the thin films by X-ray diffraction, scanning electron microscopy, surface roughness and contact angle measurement, thermoelectric power measurement and optical studies. This hydrophobic, p-type material with wide band gap will be helpful in the development of optoelectronic devices.

  5. Optical and piezoelectric properties of p-type ZnO nanowires on transparent flexible substrate for energy harvesting

    NASA Astrophysics Data System (ADS)

    Liu, Guocheng; Tam, Man Chun; Hu, Lilei; EI-Rayes, Karim; Guo, Qiuquan; Yang, Jun; Mrad, Nezih; Ban, Dayan

    2014-09-01

    High quality, controlled-structure nanowires (NWs), grown on a transparent flexible substrate, have attracted great interest as a mean of harvesting solar and mechanical energy. Clarifying their optical and piezoelectric properties is essential for this application. In this paper, vertically aligned lithium (Li) doped p-type ZnO NWs were grown, on a micro-patterned transparent flexible polyethylene naphthalate (PEN) substrate, by electrochemical deposition at 88 °C. The substrate was coated with aluminum-doped ZnO (AZO) thin layer, which served as a good seed layer and a transparent conductive oxide layer. Varying the seed layer thickness gave control of the individual NWs' diameter, density and alignment. The effect of doping on the optical band-gap, crystalline quality and Schottky barrier were investigated by X-ray diffraction (XRD) spectroscopy and piezoelectric characterization. The piezoelectric polarization induced piezo-potential in strained ZnO NWs can drive the flow of electrons without an applied electric bias, thus can be used to harvest mechanical energy and convert it into electricity. To prove this concept, flexible piezoelectric energy harvesters based on an array of ZnO NWs were fabricated. Results show that the patterned p-type NW-based energy harvester produces 26-fold output voltage and 19-fold current compared to the conventional un-doped ZnO NW energy harvester from the same acceleration input.

  6. Benefits of Carrier-Pocket Anisotropy to Thermoelectric Performance: The Case of p -Type AgBiSe2

    DOE PAGES

    Parker, David S.; May, Andrew F.; Singh, David J.

    2015-06-05

    Here we study theoretically the effects of anisotropy on the thermoelectric performance of p-type AgBiSe2. We present an apparent realization of the thermoelectric benefits of one-dimensional plate-like carrier pocket anisotropy in the valence band of this material. Based on first principles calculations we find a substantial anisotropy in the electronic structure, likely favorable for thermoelectric performance, in the valence bands of the hexagonal phase of the silver chalcogenide thermoelectric AgBiSe2, while the conduction bands are more isotropic, and in our experiments do not attain high performance. AgBiSe2 has already exhibited a ZT value of 1.5 in a high-temperature disordered fccmore » phase, but room-temperature performance has not been demonstrated. We develop a theory for the ability of anisotropy to decouple the density-of-states and conductivity effective masses, pointing out the influence of this effect in the high performance thermoelectrics Bi2Te3 and PbTe. From our first principles and Boltzmann transport calculations we find that p-type AgBiSe2 has substantial promise as a room temperature thermoelectric, and estimate its performance.« less

  7. Search for Pauli exclusion principle violating atomic transitions and electron decay with a p-type point contact germanium detector

    SciTech Connect

    Abgrall, N.; Arnquist, I. J.; Avignone, F. T.; Barabash, A. S.; Bertrand, F. E.; Bradley, A. W.; Brudanin, V.; Busch, M.; Buuck, M.; Caldwell, A. S.; Chan, Y. -D.; Christofferson, C. D.; Chu, P. -H.; Cuesta, C.; Detwiler, J. A.; Dunagan, C.; Efremenko, Yu.; Ejiri, H.; Elliott, S. R.; Finnerty, P. S.; Galindo-Uribarri, A.; Gilliss, T.; Giovanetti, G. K.; Goett, J.; Green, M. P.; Gruszko, J.; Guinn, I. S.; Guiseppe, V. E.; Henning, R.; Hoppe, E. W.; Howard, S.; Howe, M. A.; Jasinski, B. R.; Keeter, K. J.; Kidd, M. F.; Konovalov, S. I.; Kouzes, R. T.; LaFerriere, B. D.; Leon, J.; MacMullin, J.; Martin, R. D.; Massarczyk, R.; Meijer, S. J.; Mertens, S.; Orrell, J. L.; O’Shaughnessy, C.; Poon, A. W. P.; Radford, D. C.; Rager, J.; Rielage, K.; Robertson, R. G. H.; Romero-Romero, E.; Shanks, B.; Shirchenko, M.; Suriano, A. M.; Tedeschi, D.; Trimble, J. E.; Varner, R. L.; Vasilyev, S.; Vetter, K.; Vorren, K.; White, B. R.; Wilkerson, J. F.; Wiseman, C.; Xu, W.; Yakushev, E.; Yu, C. -H.; Yumatov, V.; Zhitnikov, I.

    2016-11-11

    Here, a search for Pauli-exclusion-principle-violating Kα electron transitions was performed using 89.5 kg-d of data collected with a p-type point contact high-purity germanium detector operated at the Kimballton Underground Research Facility. A lower limit on the transition lifetime of 5.8 × 1030 s at 90% C.L. was set by looking for a peak at 10.6 keV resulting from the X-ray and Auger electrons present following the transition. A similar analysis was done to look for the decay of atomic K-shell electrons into neutrinos, resulting in a lower limit of 6.8 × 1030 s at 90% C.L. It is estimated that the Majorana Demonstrator, a 44 kg array of p-type point contact detectors that will search for the neutrinoless double-beta decay of 76Ge, could improve upon these exclusion limits by an order of magnitude after three years of operation.

  8. Search for Pauli exclusion principle violating atomic transitions and electron decay with a p-type point contact germanium detector

    DOE PAGES

    Abgrall, N.; Arnquist, I. J.; Avignone, F. T.; ...

    2016-11-11

    Here, a search for Pauli-exclusion-principle-violating Kα electron transitions was performed using 89.5 kg-d of data collected with a p-type point contact high-purity germanium detector operated at the Kimballton Underground Research Facility. A lower limit on the transition lifetime of 5.8 × 1030 s at 90% C.L. was set by looking for a peak at 10.6 keV resulting from the X-ray and Auger electrons present following the transition. A similar analysis was done to look for the decay of atomic K-shell electrons into neutrinos, resulting in a lower limit of 6.8 × 1030 s at 90% C.L. It is estimated thatmore » the Majorana Demonstrator, a 44 kg array of p-type point contact detectors that will search for the neutrinoless double-beta decay of 76Ge, could improve upon these exclusion limits by an order of magnitude after three years of operation.« less

  9. Systematic Study of p-type Doping and Related Defects in III-Nitrides: Pathway toward a Nitride HBT

    DTIC Science & Technology

    2012-11-20

    photovoltaics. Silicon solar cells have a maximum theoretical efficiency of only about 29% due to the set bandgap of the material. For these single-material...16 Although beneficial for LEDs, lateral surface segregation of indium is detrimental for nitride solar cells and laser diodes, where recombination...single-junction cells , some solar energy is lost by being too low in energy, passing through the device. Furthermore, some solar energy is lost by

  10. Evolution of the symmetry of intermediate phases and their phonon spectra during the topochemical conversion of silicon into silicon carbide

    NASA Astrophysics Data System (ADS)

    Kitaev, Yu. E.; Kukushkin, S. A.; Osipov, A. V.

    2017-01-01

    A symmetry analysis of the crystal structure and the phonon spectrum during continuous topochemical conversion of silicon into silicon carbide has been carried out. The transformation of the symmetry of phonons at high-symmetry points of the Brillouin zone upon the transition from the initial cubic structure of silicon (diamond) through an intermediate cubic structure of silicon carbide to the trigonal structure of SiC has been determined. The selection rules for the infrared and Raman spectra of all the three phases under investigation have been established.

  11. Microstructure and Near Infrared Absorption of PbS Films Deposited by Chemical Bath Deposition on p-Type Si(100) Wafers

    NASA Astrophysics Data System (ADS)

    Guo, Rui-Fang; Liang, Yan; Gao, Xiao-Yong; Zhu, He-Jie; Zhang, Sa; Liu, Hong-Tao

    2014-12-01

    Nanocrystalline PbS films were synthesized on p-type Si(100) wafers using chemical bath deposition. All of the PbS films are polycrystalline in nature with face -centered cubic (fcc) rock salt structure. The average crystallite size varied from 20 to 74 nm, thereby indicating nanocrystalline films with different molar ratios. The film composed of irregular particles was homogeneous and well adhered to the substrates. Increase in thiourea concentration from 0.5 to 2.0 M resulted into an increase in the lateral particle size and film thickness, while further increase in thiourea concentration caused a decrease in particle size and film thickness. The absorption edge of the films blueshifted slightly with increased molarities of lead sources, blueshifted initially, and then redshifted with increased molarities of sulfur sources at a fixed lead source molarities. The blueshift and redshift of the absorption edge were closely related to the change in the tensile stress of the PbS films subjected to.

  12. A combination of PhP typing and β-d-glucuronidase gene sequence variation analysis for differentiation of Escherichia coli from humans and animals.

    PubMed

    Masters, N; Christie, M; Katouli, M; Stratton, H

    2015-06-01

    We investigated the usefulness of the β-d-glucuronidase gene variance in Escherichia coli as a microbial source tracking tool using a novel algorithm for comparison of sequences from a prescreened set of host-specific isolates using a high-resolution PhP typing method. A total of 65 common biochemical phenotypes belonging to 318 E. coli strains isolated from humans and domestic and wild animals were analysed for nucleotide variations at 10 loci along a 518 bp fragment of the 1812 bp β-d-glucuronidase gene. Neighbour-joining analysis of loci variations revealed 86 (76.8%) human isolates and 91.2% of animal isolates were correctly identified. Pairwise hierarchical clustering improved assignment; where 92 (82.1%) human and 204 (99%) animal strains were assigned to their respective cluster. Our data show that initial typing of isolates and selection of common types from different hosts prior to analysis of the β-d-glucuronidase gene sequence improves source identification. We also concluded that numerical profiling of the nucleotide variations can be used as a valuable approach to differentiate human from animal E. coli. This study signifies the usefulness of the β-d-glucuronidase gene as a marker for differentiating human faecal pollution from animal sources.

  13. Photoelectrical Properties of p-TYPE and n-TYPE Electrical Conductivity Amorphous Carbon Thin Films for Application in Economical Carbon-Based Solar Cells

    NASA Astrophysics Data System (ADS)

    Rusop, M.; Soga, T.; Jimbo, T.

    The successful deposition of boron (B)-doped p-type (p-C:B) and phosphorous (P)-doped n-type (n-C:P) carbon (C) films, and fabrication of p-C:B on silicon (Si) substrate (p-C:B/n-Si) and n-C:P/p-Si cells by the technique of pulsed laser deposition (PLD) using graphite target is reported. The cells' performances are represented in the dark I-V rectifying curve and I-V working curve under illumination when exposed to AM 1.5 illumination condition (100 mW/cm2, 25°C). The open circuit voltage (Voc) and short circuit current density (Jsc) for p-C:B/n-Si are observed to vary from 230-250 mV and 1.5-2.2 mA/cm2, respectively, and to vary from 215-265 mV and 7.5-10.5 mA/cm2, respectively, for n-C:P/p-Si cells. The p-C:B/n-Si cell fabricated using the target with the amount of B by 3 Bwt% shows highest energy conversion efficiency, η = 0.20%, and fill factor, FF = 45%, while, the n-C:P/p-Si cell with the amount of P by 7 Pwt% shows highest energy conversion efficiency, η = 1.14%, and fill factor, FF = 41%. The quantum efficiencies (QE) of the p-C:B/n-Si and n-C:P/p-Si cells are observed to improve with Bwt% and Pwt%, respectively. The contributions of QE are suggested to be due to photon absorption by carbon layer in the lower wavelength region (below 750 nm) and Si substrates in the higher wavelength region. The dependence of B and P content on the electrical and optical properties of the deposited films, and the photovoltaic characteristics of the respective p-C:B/n-Si and n-C:P/p-Si heterojunction photovoltaic cells, are discussed.

  14. Light Weight Silicon Mirrors for Space Instrumentation

    NASA Technical Reports Server (NTRS)

    Bly, Vincent T.; Hill, Peter C.; Hagopian, John G.; Strojay, Carl R.; Miller, Timothy

    2012-01-01

    Each mirror is a monolithic structure from a single crystal of silicon. The mirrors are light weighted after the optical surface is ground and polished. Mirrors made during the initial phase of this work were typically 1/50 lambda or better (RMS at 633 n m)

  15. 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.

  16. Study of impurity states in p-type Hg1-xCdxTe using far-infrared spectroscopy

    NASA Astrophysics Data System (ADS)

    Li, Biao; Gui, Yongsheng; Chen, Zhanghai; Ye, Hongjuan; Chu, Junhao; Wang, Shanli; Ji, Rongbin; He, Li

    1998-09-01

    This letter reports the far-infrared (FIR) transmission spectra of undoped and Sb-doped p-type Hg1-xCdxTe films grown by a liquid-phase epitaxy (LPE) or molecular-beam epitaxy (MBE) technique. The activation energies of cation vacancy acceptor are found to be ˜10-12 meV and are almost independent on Cd composition. The absorption strength per Hg vacancy, useful for evaluating the cation vacancy density from the absorption spectra, is derived as 3.4×10-12 cm. Further, Zeeman splitting resulting from two different acceptors is observed from magnetotransmission measurement for the Sb-doped LPE sample, and light hole effective mass is estimated. FIR transmission seems to be a powerful tool for nondestructive characterization of impurity states in Hg1-xCdxTe.

  17. Multistrip synthetic single-crystal-diamond photodiode based on a p-type/intrinsic/Schottky metal transverse configuration

    NASA Astrophysics Data System (ADS)

    Ciancaglioni, I.; Marinelli, Marco; Milani, E.; Prestopino, G.; Verona, C.; Verona-Rinati, G.; Angelone, M.; Pillon, M.; Dolbnya, I.; Sawhney, K.; Tartoni, N.

    2011-04-01

    A synthetic multistrip single-crystal-diamond detector based on a p-type/intrinsic diamond/Schottky metal transverse configuration, operating at zero-bias voltage, was developed. The device was characterized at the Diamond Light Source synchrotron in Harwell (UK) under monochromatic high-flux X-ray beams from 6 to 20 keV and a micro-focused 10 keV beam with a spot size of ~3 μm. No significant pixel-to-pixel variation of both spectral responsivity and time response, high spatial resolution and good signal uniformity along each strip were found, suggesting the tested device structure as a promising sensor for X-ray and UV radiation imaging.

  18. Broadband InGaAs quantum dot-in-a-well solar cells of p-type wells

    NASA Astrophysics Data System (ADS)

    Tzeng, T. E.; Chuang, K. Y.; Lay, T. S.; Chang, C. H.

    2013-09-01

    Broadband InxGa1-xAs quantum dot-in-a-well (DWell) solar cells are grown by stacking layers of composition-tailored InxGa1-xAs (x=1, 0.75, and 0.65) quantum dots on p-type In0.1Ga0.9As quantum wells (QWs). Doping concentration and growth temperature for the Be-doped quantum wells are optimized to enhance the conversion efficiency (η). The broadband DWell solar cell of Be: 2×1017 cm-3 QWs grown at 570 °C shows the best photovoltaic characteristics of η=10.86%, which is 3% higher than that of the GaAs baseline solar cell.

  19. Mobility and carrier density in p-type GaAs nanowires measured by transmission Raman spectroscopy.

    PubMed

    Ketterer, Bernt; Uccelli, Emanuele; Fontcuberta i Morral, Anna

    2012-03-07

    The unambiguous measurement of carrier concentration and mobility in semiconductor nanowires remains a challenging task. This is a consequence of their one-dimensional nature and the incompatibility with Hall or van der Pauw measurements. We propose a method that allows the direct determination of mobility and carrier concentration in nanowires in a contact-less manner. We demonstrate how forward Raman scattering enables the measurement of phonon-plasmon interactions. By applying this method to p-type GaAs nanowires, we were able to directly obtain values of the carrier concentration between 3.0 × 10(17) and 7.4 × 10(18) cm(-3) and a mobility of 31 cm(2) (V s)(-1) at room temperature. This study opens the path towards the study of plasmon-phonon interactions in semiconductor nanowires.

  20. Mobility and carrier density in p-type GaAs nanowires measured by transmission Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Ketterer, Bernt; Uccelli, Emanuele; Fontcuberta I Morral, Anna

    2012-02-01

    The unambiguous measurement of carrier concentration and mobility in semiconductor nanowires remains a challenging task. This is a consequence of their one-dimensional nature and the incompatibility with Hall or van der Pauw measurements. We propose a method that allows the direct determination of mobility and carrier concentration in nanowires in a contact-less manner. We demonstrate how forward Raman scattering enables the measurement of phonon-plasmon interactions. By applying this method to p-type GaAs nanowires, we were able to directly obtain values of the carrier concentration between 3.0 × 1017 and 7.4 × 1018 cm-3 and a mobility of 31 cm2 (V s)-1 at room temperature. This study opens the path towards the study of plasmon-phonon interactions in semiconductor nanowires.

  1. Photocatalytic reduction of carbon dioxide on p-type CaFe[sub 2]O[sub 4] powder

    SciTech Connect

    Matsumoto, Yasumichi; Obata, Michio; Hombo, Jukichi )

    1994-03-17

    The photocatalytic reduction of CO[sub 2] on p-type CaFe[sub 2]O[sub 4] powder has been studied in water. CH[sub 3]OH and HCHO were produced under illumination. The additions of NaH[sub 2]PO[sub 2] and BaCO[sub 3] promoted the CO[sub 2] reduction reaction on the CaFe[sub 2]O[sub 4] photocatalyst. It was proven from the dependence of the amount of CH[sub 3]OH produced on the wavelength of the illuminated light that the electron produced in the conduction band of the CaFe[sub 2]O[sub 4] reduces CO[sub 2]. The mechanism for the photocatalytic reduction of CO[sub 2] on CaFe[sub 2]O[sub 4] is briefly discussed. 10 refs., 4 figs.

  2. Room temperature electrical properties of solution derived p-type Cu2ZnSnS4 thin films

    NASA Astrophysics Data System (ADS)

    Gupta, Goutam Kumar; Dixit, Ambesh

    2016-05-01

    Electrical properties of solution processed Cu2ZnSnS4 (CZTS) compound semiconductor thin film structures on molybdenum (Mo) coated glass substrates are investigated using Mott-Schottky and Impedance spectroscopy measurements at room temperature. These measurements are carried out in sodium sulfate (Na2SO4) electrolytic medium at pH ~ 9.5. The inversion/depletion/accumulation regions are clearly observed in CZTS semiconductor -Na2SO4 electrolyte interface and measured flat band potential is ~ -0.27 V for CZTS thin film electrode. The positive slope of the depletion region confirms the intrinsic p-type characteristics of CZTS thinfilms with ~ 2.5× 1019 holes/m3. The high frequency impedance measurements showed ~ 30 Ohm electrolyte resistance for the investigated configuration.

  3. Mammalian copper-transporting P-Type ATPases, ATP7A and ATP7B: Emerging roles

    PubMed Central

    La Fontaine, Sharon; Ackland, M. Leigh; Mercer, Julian F.B.

    2010-01-01

    Copper (Cu) has a role in a diverse and increasing number of pathways, physiological and disease processes. These roles are testament to the fundamental importance of Cu in biology and the need to understand the mechanisms that regulate Cu homeostasis. The mammalian Cu-transporting P-type ATPases ATP7A and ATP7B are two key proteins that regulate the Cu status of the body. They transport Cu across cellular membranes for biosynthetic and protective functions, enabling Cu to fulfill its role as a structural cofactor for many essential enzymes, and to prevent a toxic build-up of Cu inside cells. A variety of regulatory mechanisms operate at transcriptional and post-translational levels to ensure adequate Cu supplies for both physiological and pathophysiological processes. This review summarizes the recent literature that is revealing the emerging roles of the Cu-ATPases in health and disease. PMID:19922814

  4. Fabrication and Characterization of a Single Hole Transistor in p-type GaAs/AlGaAs Heterostructures

    SciTech Connect

    Tracy, Lisa A; Reno, John L.; Hargett, Terry W.

    2015-09-01

    Most spin qubit research to date has focused on manipulating single electron spins in quantum dots. However, hole spins are predicted to have some advantages over electron spins, such as reduced coupling to host semiconductor nuclear spins and the ability to control hole spins electrically using the large spin-orbit interaction. Building on recent advances in fabricating high-mobility 2D hole systems in GaAs/AlGaAs heterostructures at Sandia, we fabricate and characterize single hole transistors in GaAs. We demonstrate p-type double quantum dot devices with few-hole occupation, which could be used to study the physics of individual hole spins and control over coupling between hole spins, looking towards eventual applications in quantum computing. Intentionally left blank

  5. Interface states and internal photoemission in p-type GaAs metal-oxide-semiconductor surfaces

    NASA Technical Reports Server (NTRS)

    Kashkarov, P. K.; Kazior, T. E.; Lagowski, J.; Gatos, H. C.

    1983-01-01

    An interface photodischarge study of p-type GaAs metal-oxide-semiconductor (MOS) structures revealed the presence of deep interface states and shallow donors and acceptors which were previously observed in n-type GaAs MOS through sub-band-gap photoionization transitions. For higher photon energies, internal photoemission was observed, i.e., injection of electrons to the conduction band of the oxide from either the metal (Au) or from the GaAs valence band; the threshold energies were found to be 3.25 and 3.7 + or - 0.1 eV, respectively. The measured photoemission current exhibited a thermal activation energy of about 0.06 eV, which is consistent with a hopping mechanism of electron transport in the oxide.

  6. Reliability tests of electroless barriers against copper diffusion under bias-temperature stress with n- and p-type substrates

    NASA Astrophysics Data System (ADS)

    Ueno, Kazuyoshi; Fujishima, Shota; Yamashita, Makoto; Mitsumori, Akiyoshi

    2016-05-01

    To investigate the similarity and difference of substrate conduction type in the time-dependent dielectric breakdown (TDDB) tests for the barrier integrity against Cu diffusion under bias-temperature stress (BTS), the TDDB reliability of electroless NiB and CoWP/NiB was determined by metal oxide semiconductor (MOS) structures on n-type Si (n-Si) substrates, and the test results were compared with those using p-type Si (p-Si) substrates. The TDDB results and mechanism were observed to be qualitatively the same as Cu diffusion for both conduction types. However, the TDDB lifetime using p-Si was found to be potentially shorter because of the reverse bias conditions than that using n-Si under the forward bias conditions.

  7. Photoinduced magnetization effect in a p -type Hg1 -xMnxTe single crystal investigated by infrared photoluminescence

    NASA Astrophysics Data System (ADS)

    Zhu, Liangqing; Shao, Jun; Chen, Xiren; Li, Yanqiu; Zhu, Liang; Qi, Zhen; Lin, Tie; Bai, Wei; Tang, Xiaodong; Chu, Junhao

    2016-10-01

    Photoinduced magnetization (PIM) effect of Hg1 -xMnxTe provides an attractive solution for realizing the quantum anomalous Hall effect in quantum wells with a light field. In this paper, the PIM effect of p -type Hg0.74Mn0.26Te single crystal was investigated by power-, polarization- and temperature-dependent photoluminescence (PL) measurements in both reflection and transmission geometries. Giant Zeeman splitting and polarization of PL spectra were observed without an external magnetic field evolving with excitation-power density of the pumping laser and temperature, which were accounted for by the PIM effect. The occurrence of the PIM was qualitatively understandable by the carrier-mediated mean-field theory known as the Zener model. The results indicate that infrared PL measurements with enhanced sensitivity and signal-to-noise ratio can serve as a convenient pathway for clarifying the PIM effect of semimagnetic semiconductors.

  8. Silicon on graphite cloth

    SciTech Connect

    Rand, J.A.; Cotter, J.E.; Thomas, C.J.; Ingram, A.E.; Bai, Y.B.; Ruffins, T.R.; Barnett, A.M.

    1994-12-31

    A new polycrystalline silicon solar cell has been developed that utilizes commercially available graphite cloth as a substrate. This solar cell has achieved an energy conversion efficiency of 13.4% (AM1.5G). It is believed that this is a record efficiency for a silicon solar cell formed on a graphite substrate. The silicon-on-fabric structure is comprised of a thin layer of polycrystalline silicon grown directly on the graphite fabric substrate. The structure is fabricated by a low-cost ribbon process that avoids the expense and waste of wafering. The fabric substrate gives structural support to the thin device. Critical to the achievement of device quality silicon layers is control over impurities in the graphite fabric. The silicon-on-fabric technology has the potential to supply lightweight, low-cost solar cells to weight-sensitive markets at a fraction of the cost of conventionally thinned wafers.

  9. Silicon micro-mold

    DOEpatents

    Morales, Alfredo M.

    2006-10-24

    The present invention describes a method for rapidly fabricating a robust 3-dimensional silicon-mold for use in preparing complex metal micro-components. The process begins by depositing a conductive metal layer onto one surface of a silicon wafer. A thin photoresist and a standard lithographic mask are then used to transfer a trace image pattern onto the opposite surface of the wafer by exposing and developing the resist. The exposed portion of the silicon substrate is anisotropically etched through the wafer thickness down to conductive metal layer to provide an etched pattern consisting of a series of rectilinear channels and recesses in the silicon which serve as the silicon micro-mold. Microcomponents are prepared with this mold by first filling the mold channels and recesses with a metal deposit, typically by electroplating, and then removing the silicon micro-mold by chemical etching.

  10. Growth of silicon bump induced by swift heavy ion at the silicon oxide-silicon interface

    SciTech Connect

    Carlotti, J.-F.; Touboul, A.D.; Ramonda, M.; Caussanel, M.; Guasch, C.; Bonnet, J.; Gasiot, J.

    2006-01-23

    Thin silicon oxide layers on silicon substrates are investigated by scanning probe microscopy before and after irradiation with 210 MeV Au+ ions. After irradiation and complete chemical etching of the silicon oxide layer, silicon bumps grown on the silicon surface are observed. It is shown that each impinging ion induces one silicon bump at the interface. This observation is consistent with the thermal spike theory. Ion energy loss is transferred to the oxide and induces local melting. Silicon-bump formation is favored when the oxide and oxide-silicon interface are silicon rich.

  11. A study of p-type ohmic contacts to InAlAs/InGaAs heterostructures

    SciTech Connect

    Briggs, R.D.; Howard, A.J.; Baca, A.G.; Hafich, M.J.; Vawter, G.A.

    1995-12-31

    Optical modulators operating at near-infrared wavelengths are of interest for a variety of applications including bidirectional communications and optical interconnects. The fabrication of 1.06 {micro}m and 1.32 {micro}m operating wavelength strained-layer-superlattice vertical-cavity optoelectronic modulators requires the formation of a p-type ohmic contact to the InAlAs/InGaAs quarter-wave bottom mirror stack. In this study, BeAu and TiPtAu p-type ohmic contact metallization schemes were evaluated for use on molecular beam epitaxy (MBE) grown In{sub .10}Al{sub .90}As/In{sub .12}Ga{sub .88}As and In{sub .32}Al{sub .68}As/In{sub .33}Ga{sub .67}As device heterostructures. Recessed and nonrecessed transmission line measurement (TLM) structures were fabricated and evaluated as a function of rapid thermal anneal (RTA) temperatures over the range of 360 C--420 C. Atomic force microscopy (AFM) was used to determine the surface morphology of each sample for evidence of metal or material degradation. For contacts directly on InGaAs layers, TiPtAu contacts had relatively high specific contact resistance values of {rho}{sub c} {approximately} 3 {times} 10{sup {minus}4} {Omega}cm{sup 2} and displayed no dependence on the anneal. The BeAu contacts had minimum specific contact resistance values of {rho}{sub c} {approximately} 5 {times} 10{sup {minus}7} {Omega}cm{sup 2} but showed evidence of degradation at higher temperatures. Contacts directly made to InAlAs layers had minimum specific contact resistances of {rho}{sub c} {approximately} 4 {times} 10{sup {minus}5} {Omega}cm{sup 2} and were improved slightly with the addition of a thin GaAs layer.

  12. Interaction of three-finger toxins with phospholipid membranes: comparison of S- and P-type cytotoxins

    PubMed Central

    2004-01-01

    The CTs (cytotoxins) I and II are positively charged three-finger folded proteins from venom of Naja oxiana (the Central Asian cobra). They belong to S- and P-type respectively based on Ser-28 and Pro-30 residues within a putative phospholipid bilayer binding site. Previously, we investigated the interaction of CTII with multilamellar liposomes of dipalmitoylphosphatidylglycerol by wide-line 31P-NMR spectroscopy. To compare interactions of these proteins with phospholipids, we investigated the interaction of CTI with the multilamellar liposomes of dipalmitoylphosphatidylglycerol analogously. The effect of CTI on the chemical shielding anisotropy and deformation of the liposomes in the magnetic field was determined at different temperatures and lipid/protein ratios. It was found that both the proteins do not affect lipid organization in the gel state. In the liquid crystalline state of the bilayer they disturb lipid packing. To get insight into the interactions of the toxins with membranes, Monte Carlo simulations of CTI and CTII in the presence of the bilayer membrane were performed. It was found that both the toxins penetrate into the bilayer with the tips of all the three loops. However, the free-energy gain on membrane insertion of CTI is smaller (by ≈7 kcal/mol; 1 kcal≡4.184 kJ) when compared with CTII, because of the lower hydrophobicity of the membrane-binding site of CTI. These results clearly demonstrate that the P-type cytotoxins interact with membranes stronger than those of the S-type, although the mode of the membrane insertion is similar for both the types. PMID:15584897

  13. Surface states and conductivity of silicon nano-wires

    NASA Astrophysics Data System (ADS)

    Kumar Bhaskar, Umesh; Pardoen, Thomas; Passi, Vikram; Raskin, Jean-Pierre

    2013-04-01

    The transport characteristics of low dimensional semiconductors like silicon nano-wires (SiNWs) rarely conform to expectations from geometry and dopant density, exhibiting significant variations as a function of different surface terminations/conditions. The association of these mechanisms with surface states and their exact influence on practical SiNW devices still remains largely unclear. Herein, we report on the influence of surface state charge distributions on SiNW transport characteristics. For this study, p-type SiNW devices with widths of 50, 100, and 2000 nm are fabricated from 25, 50, and 200 nm-thick SOI wafers. A ˜five order difference in effective carrier concentration was observed in the initial SiNWs characteristics, when comparing SiNWs fabricated with and without a thermal oxide. The removal of the surface oxide by a hydrogen fluoride (HF) treatment results in a SiNW conductance drop up to ˜six orders of magnitude. This effect is from a surface depletion of holes in the SiNW induced by positive surface charges deposited as a result of the HF treatment. However, it is observed that this charge density is transient and is dissipated with the re-growth of an oxide layer. In summary, the SiNW conductance is shown to vary by several orders of magnitude, while comparing its characteristics for the three most studied surface conditions: with a native oxide, thermal oxide and HF induced H-terminations. These results emphasize the necessity to interpret the transport characteristics of SiNWs with respect to its surface condition, during future investigations pertaining to the physical properties of SiNWs, like its piezo-resistance. As a sequel, prospects for efficiently sensing an elementary reduction/oxidation chemical process by monitoring the variation of SiNW surface potential, or in practice the SiNW conductance, is demonstrated.

  14. Highly porous silicon membranes fabricated from silicon nitride/silicon stacks.

    PubMed

    Qi, Chengzhu; Striemer, Christopher C; Gaborski, Thomas R; McGrath, James L; Fauchet, Philippe M

    2014-07-23

    Nanopore formation in silicon films has previously been demonstrated using rapid thermal crystallization of ultrathin (15 nm) amorphous Si films sandwiched between nm-thick SiO2 layers. In this work, the silicon dioxide barrier layers are replaced with silicon nitride, resulting in nanoporous silicon films with unprecedented pore density and novel morphology. Four different thin film stack systems including silicon nitride/silicon/silicon nitride (NSN), silicon dioxide/silicon/silicon nitride (OSN), silicon nitride/silicon/silicon dioxide (NSO), and silicon dioxide/silicon/silicon dioxide (OSO) are tested under different annealing temperatures. Generally the pore size, pore density, and porosity positively correlate with the annealing temperature for all four systems. The NSN system yields substantially higher porosity and pore density than the OSO system, with the OSN and NSO stack characteristics fallings between these extremes. The higher porosity of the Si membrane in the NSN stack is primarily due to the pore formation enhancement in the Si film. It is hypothesized that this could result from the interfacial energy difference between the silicon/silicon nitride and silicon/silicon dioxide, which influences the Si crystallization process.

  15. SILICON CARBIDE FOR SEMICONDUCTORS

    DTIC Science & Technology

    This state-of-the-art survey on silicon carbide for semiconductors includes a bibliography of the most important references published as of the end...of 1964. The various methods used for growing silicon carbide single crystals are reviewed, as well as their properties and devices fabricated from...them. The fact that the state of-the-art of silicon carbide semiconductors is not further advanced may be attributed to the difficulties of growing

  16. Silicon Carbide Shapes.

    DTIC Science & Technology

    Free-standing silicon carbide shapes are produced by passing a properly diluted stream of a reactant gas, for example methyltrichlorosilane, into a...reaction chamber housing a thin walled, hollow graphite body heated to 1300-1500C. After the graphite body is sufficiently coated with silicon carbide , the...graphite body is fired, converting the graphite to gaseous CO2 and CO and leaving a silicon carbide shaped article remaining.

  17. The CDFII Silicon Detector

    SciTech Connect

    Julia Thom

    2004-07-23

    The CDFII silicon detector consists of 8 layers of double-sided silicon micro-strip sensors totaling 722,432 readout channels, making it one of the largest silicon detectors in present use by an HEP experiment. After two years of data taking, we report on our experience operating the complex device. The performance of the CDFII silicon detector is presented and its impact on physics analyses is discussed. We have already observed measurable effects from radiation damage. These results and their impact on the expected lifetime of the detector are briefly reviewed.

  18. Micromachined silicon electrostatic chuck

    DOEpatents

    Anderson, Robert A.; Seager, Carleton H.

    1996-01-01

    An electrostatic chuck is faced with a patterned silicon plate 11, created y micromachining a silicon wafer, which is attached to a metallic base plate 13. Direct electrical contact between the chuck face 15 (patterned silicon plate's surface) and the silicon wafer 17 it is intended to hold is prevented by a pattern of flat-topped silicon dioxide islands 19 that protrude less than 5 micrometers from the otherwise flat surface of the chuck face 15. The islands 19 may be formed in any shape. Islands may be about 10 micrometers in diameter or width and spaced about 100 micrometers apart. One or more concentric rings formed around the periphery of the area between the chuck face 15 and wafer 17 contain a low-pressure helium thermal-contact gas used to assist heat removal during plasma etching of a silicon wafer held by the chuck. The islands 19 are tall enough and close enough together to prevent silicon-to-silicon electrical contact in the space between the islands, and the islands occupy only a small fraction of the total area of the chuck face 15, typically 0.5 to 5 percent. The pattern of the islands 19, together with at least one hole 12 bored through the silicon veneer into the base plate, will provide sufficient gas-flow space to allow the distribution of the helium thermal-contact gas.

  19. Micromachined silicon electrostatic chuck

    DOEpatents

    Anderson, R.A.; Seager, C.H.

    1996-12-10

    An electrostatic chuck is faced with a patterned silicon plate, created by micromachining a silicon wafer, which is attached to a metallic base plate. Direct electrical contact between the chuck face (patterned silicon plate`s surface) and the silicon wafer it is intended to hold is prevented by a pattern of flat-topped silicon dioxide islands that protrude less than 5 micrometers from the otherwise flat surface of the chuck face. The islands may be formed in any shape. Islands may be about 10 micrometers in diameter or width and spaced about 100 micrometers apart. One or more concentric rings formed around the periphery of the area between the chuck face and wafer contain a low-pressure helium thermal-contact gas used to assist heat removal during plasma etching of a silicon wafer held by the chuck. The islands are tall enough and close enough together to prevent silicon-to-silicon electrical contact in the space between the islands, and the islands occupy only a small fraction of the total area of the chuck face, typically 0.5 to 5 percent. The pattern of the islands, together with at least one hole bored through the silicon veneer into the base plate, will provide sufficient gas-flow space to allow the distribution of the helium thermal-contact gas. 6 figs.

  20. Compounding with Silicones.

    PubMed

    Allen, Loyd V

    2015-01-01

    Since the 1940s, methylchlorosilanes have been used to treat glassware to prevent blood from clotting. The use of silicones in pharmaceutical and medical applications has grown to where today they are used in many life-saving devices (pacemakers, hydrocephalic shunts) and pharmaceutical applications from tubing, to excipients in topical formulations, to adhesives to affix transdermal drug delivery systems, and are also being used in products as active pharmaceutical ingredients, such as antiflatulents. About 60% of today's skin-care products now contain some type of silicone where they are considered safe and are known to provide a pleasant "silky-touch," non-greasy, and non-staining feel. Silicones exhibit many useful characteristics, and the safety of these agents supports their numerous applications; their biocompatibility is partially due to their low-chemical reactivity displayed by silicones, low-surface energy, and their hydrophobicity. Silicones are used both as active ingredients and as excipients. In addition is their use for "siliconization," or surface treatment, of many parenteral packaging components. Dimethicone and silicone oil are used as lubricants on stoppers to aid machineability, in syringes to aid piston movement, or on syringe needles to reduce pain upon injection. Silicones are also useful in pharmaceutical compounding as is discussed in this artiele included with this article are in developing formulations with silicones.