WorldWideScience

Sample records for pn inp solar

  1. Comparative modeling of InP solar cell structures

    Science.gov (United States)

    Jain, R. K.; Weinberg, I.; Flood, D. J.

    1991-01-01

    The comparative modeling of p(+)n and n(+)p indium phosphide solar cell structures is studied using a numerical program PC-1D. The optimal design study has predicted that the p(+)n structure offers improved cell efficiencies as compared to n(+)p structure, due to higher open-circuit voltage. The various cell material and process parameters to achieve the maximum cell efficiencies are reported. The effect of some of the cell parameters on InP cell I-V characteristics was studied. The available radiation resistance data on n(+)p and p(+)p InP solar cells are also critically discussed.

  2. Hydrogen Passivation of N(+)P and P(+)N Heteroepitaxial InP Solar Cell Structures

    Science.gov (United States)

    Chatterjee, B.; Davis, W. C.; Ringel, S. A.; Hoffman, R., Jr.

    1995-01-01

    Dislocations and related point defect complexes caused by lattice mismatch currently limit the performance of heteroepitaxial InP cells by introducing shunting paths across the active junction and by the formation of deep traps within the base region. We have previously demonstrated that plasma hydrogenation is an effective and stable means to passivate the electrical activity of such defects in specially designed heteroepitaxial InP test structures to probe hydrogen passivation at typical base depths within a cell structure. In this work, we present our results on the hydrogen passivation of actual heteroepitaxial n(+)p and p(+)n InP cell structures grown on GaAs substrates by metalorganic chemical vapor deposition (MOCVD). We have found that a 2 hour exposure to a 13.56 MHz hydrogen plasma at 275 C reduces the deep level concentration in the base regions of both n(+)p and p(+)n heteroepitaxial InP cell structures from as-grown values of 5 - 7 x 10(exp 14)/cc, down to 3 - 5 x 10(exp 12)/cc. All dopants were successfully reactivated by a 400 C, 5 minute anneal With no detectable activation of deep levels. I-V analysis indicated a subsequent approx. 100 fold decrease In reverse leakage current at -1 volt reverse bias, and an improved built in voltage for the p(+)n structures. ln addition to being passivated,dislocations are also shown to participate in secondary interactions during hydrogenation. We find that the presence of dislocations enhances hydrogen diffusion into the cell structure, and lowers the apparent dissociation energy of Zn-H complexes from 1.19 eV for homoepitaxial Zn-doped InP to 1.12 eV for heteroepitaxial Zn-doped InP. This is explained by additional hydrogen trapping at dislocations subsequent to the reactivation of Zn dopants after hydrogenation.

  3. Hydrogen passivation of N(+)-P and P(+)-N heteroepitaxial InP solar cell structures

    Science.gov (United States)

    Chatterjee, Basab; Davis, William C.; Ringel, Steve A.; Hoffman, Richard, Jr.

    1996-01-01

    Dislocations and related point defect complexes caused by lattice mismatch currently limit the performance of heteroepitaxial InP cells by introducing shunting paths across the active junction and by the formation of deep traps within the base region. We have previously demonstrated that plasma hydrogenation is an effective and stable means to passivate the electrical activity of such defects in specially designed heteroepitaxial InP test structures to probe hydrogen passivation at typical base depths within a cell structure. In this work, we present our results on the hydrogen passivation of actual heteroepitaxial n-p and p-n InP cell structures grown on GaAs substrates by metalorganic chemical vapor deposition (MOCVD). We have found that a 2 hour exposure to a 13.56 MHz hydrogen plasma at 275 C reduces the deep level concentration in the base regions of both n(+)-p and p(+)-n heteroepitaxial InP cell structures from as-grown values of 5-7 x 10(exp 14) cm(exp -3), down to 3-5 x 10(exp 12) cm(exp -3). All dopants were successfully reactivated by a 400 C, 5 minute anneal with no detectable activation of deep levels. One to five analysis indicated a subsequent approximately 100 fold decrease in reverse leakage current at -1 volt reverse bias, and an improved built in voltage for the p(+)-n structures. In addition to being passivated, dislocations are also shown to participate in secondary interactions during hydrogenation. We find that the presence of dislocations enhances hydrogen diffusion into the cell structure, and lowers the apparent dissociation energy of Zn-H complexes from 1.19 eV for homoepitaxial Zn-doped InP to 1.12 eV for heteroepitaxial Zn-doped InP. This is explained by additional hydrogen trapping at dislocations subsequent to the reactivation of Zn dopants after hydrogenation.

  4. Hydrogen passivation of n+p and p+n heteroepitaxial InP solar cell structures

    Science.gov (United States)

    Chatterjee, B.; Ringel, S. A.; Hoffman, R., Jr.

    1995-01-01

    High-efficiency, heteroepitaxial (HE) InP solar cells, grown on GaAs, Si or Ge substrates, are desirable for their mechanically strong, light-weight and radiation-hard properties. However, dislocations, caused by lattice mismatch, currently limit the performance of the HE cells. This occurs through shunting paths across the active photovoltaic junction and by the formation of deep levels. In previous work we have demonstrated that plasma hydrogenation is an effective and stable means to passivate the electrical activity of dislocations in specially designed HE InP test structures. In this work, we present the first report of successful hydrogen passivation in actual InP cell structures grown on GaAs substrates by metalorganic chemical vapor deposition (MOCVD). We have found that a 2 hour exposure to a 13.56 MHz hydrogen plasma at 275 C reduces the deep level concentration in HE n+n InP cell structures from as-grown values of approximately 10(exp 15)/cm(exp -3), down to 1-2 x 10(exp 13)/cm(exp -3). The deep levels in the p-type base region of the cell structure match those of our earlier p-type test structures, which were attributed to dislocations or related point defect complexes. All dopants were successfully reactivated by a 400 C, 5 minute anneal with no detectable activation of deep levels. I-V analysis indicated a subsequent approximately 10 fold decrease in reverse leakage current at -1 volt reverse bias, and no change in the forward biased series resistance of the cell structure which indicates complete reactivation of the n+ emitter. Furthermore, electrochemical C-V profiling indicates greatly enhanced passivation depth, and hence hydrogen diffusion, for heteroepitaxial structures when compared with identically processed homoepitaxial n+p InP structures. An analysis of hydrogen diffusion in dislocated InP will be discussed, along with comparisons of passivation effectiveness for n+p versus p+n heteroepitaxial cell configurations. Preliminary hydrogen

  5. P/N InP solar cells on Ge wafers

    Science.gov (United States)

    Wojtczuk, Steven; Vernon, Stanley; Burke, Edward A.

    1994-01-01

    Indium phosphide (InP) P-on-N one-sun solar cells were epitaxially grown using a metalorganic chemical vapor deposition process on germanium (Ge) wafers. The motivation for this work is to replace expensive InP wafers, which are fragile and must be thick and therefore heavy, with less expensive Ge wafers, which are stronger, allowing use of thinner, lighter weight wafers. An intermediate InxGs1-xP grading layer starting as In(0.49)Ga(0.51) at the GaAs-coated Ge wafer surface and ending as InP at the top of the grading layer (backside of the InP cell) was used to attempt to bend some of the threading dislocations generated by lattice-mismatch between the Ge wafer and InP cell so they would be harmlessly confined in this grading layer. The best InP/Ge cell was independently measured by NASA-Lewis with a one-sun 25 C AMO efficiently measured by NASA-Lewis with a one-circuit photocurrent 22.6 mA/sq cm. We believe this is the first published report of an InP cell grown on a Ge wafer. Why get excited over a 9 percent InP/Ge cell? If we look at the cell weight and efficiency, a 9 percent InP cell on an 8 mil Ge wafer has about the same cell power density, 118 W/kg (BOL), as the best InP cell ever made, a 19 percent InP cell on an 18 mil InP wafer, because of the lighter Ge wafer weight. As cell panel materials become lighter, the cell weight becomes more important, and the advantage of lightweight cells to the panel power density becomes more important. In addition, although InP/Ge cells have a low beginning-of-life (BOL) efficiency due to dislocation defects, the InP/Ge cells are very radiation hard (end-of-life power similar to beginning-of-life). We have irradiated an InP/Ge cell with alpha particles to an equivalent fluence of 1.6 x 10(exp 16) 1 MeV electrons/sq cm and the efficiency is still 83 percent of its BOL value. At this fluence level, the power output of these InP/Ge cells matches the GaAs/Ge cell data tabulated in the JPL handbook. Data are presented

  6. Optimized efficiency in InP nanowire solar cells with accurate 1D analysis

    Science.gov (United States)

    Chen, Yang; Kivisaari, Pyry; Pistol, Mats-Erik; Anttu, Nicklas

    2018-01-01

    Semiconductor nanowire arrays are a promising candidate for next generation solar cells due to enhanced absorption and reduced material consumption. However, to optimize their performance, time consuming three-dimensional (3D) opto-electronics modeling is usually performed. Here, we develop an accurate one-dimensional (1D) modeling method for the analysis. The 1D modeling is about 400 times faster than 3D modeling and allows direct application of concepts from planar pn-junctions on the analysis of nanowire solar cells. We show that the superposition principle can break down in InP nanowires due to strong surface recombination in the depletion region, giving rise to an IV-behavior similar to that with low shunt resistance. Importantly, we find that the open-circuit voltage of nanowire solar cells is typically limited by contact leakage. Therefore, to increase the efficiency, we have investigated the effect of high-bandgap GaP carrier-selective contact segments at the top and bottom of the InP nanowire and we find that GaP contact segments improve the solar cell efficiency. Next, we discuss the merit of p-i-n and p-n junction concepts in nanowire solar cells. With GaP carrier selective top and bottom contact segments in the InP nanowire array, we find that a p-n junction design is superior to a p-i-n junction design. We predict a best efficiency of 25% for a surface recombination velocity of 4500 cm s-1, corresponding to a non-radiative lifetime of 1 ns in p-n junction cells. The developed 1D model can be used for general modeling of axial p-n and p-i-n junctions in semiconductor nanowires. This includes also LED applications and we expect faster progress in device modeling using our method.

  7. InP nanowire array solar cell with cleaned sidewalls

    NARCIS (Netherlands)

    Cui, Y.; Plissard, S.; Wang, J.; Vu, T.T.T.; Smalbrugge, E.; Geluk, E.J.; de Vries, T.; Bolk, J.; Trainor, M.J.; Verheijen, M.A.; Haverkort, J.E.M.; Bakkers, E.P.A.M.

    2013-01-01

    We have fabricated InP nanowire array solar cells with an axial p-n junction. Catalyst gold nanoparticles were first patterned into an array by nanoimprint lithography. The nanowire array was grown in 19 minutes by vapor-liquid-solid growth. The sidewalls were in-situ etched by HCl and ex-situ

  8. Systems and methods for advanced ultra-high-performance InP solar cells

    Science.gov (United States)

    Wanlass, Mark

    2017-03-07

    Systems and Methods for Advanced Ultra-High-Performance InP Solar Cells are provided. In one embodiment, an InP photovoltaic device comprises: a p-n junction absorber layer comprising at least one InP layer; a front surface confinement layer; and a back surface confinement layer; wherein either the front surface confinement layer or the back surface confinement layer forms part of a High-Low (HL) doping architecture; and wherein either the front surface confinement layer or the back surface confinement layer forms part of a heterointerface system architecture.

  9. Surface passivation of InP solar cells with InAlAs layers

    Science.gov (United States)

    Jain, Raj K.; Flood, Dennis J.; Landis, Geoffrey A.

    1993-01-01

    The efficiency of indium phosphide solar cells is limited by high values of surface recombination. The effect of a lattice-matched In(0.52)Al(0.48)As window layer material for InP solar cells, using the numerical code PC-1D is investigated. It was found that the use of InAlAs layer significantly enhances the p(+)n cell efficiency, while no appreciable improvement is seen for n(+)p cells. The conduction band energy discontinuity at the heterojunction helps in improving the surface recombination. An optimally designed InP cell efficiency improves from 15.4 percent to 23 percent AMO for a 10 nm thick InAlAs layer. The efficiency improvement reduces with increase in InAlAs layer thickness, due to light absorption in the window layer.

  10. High and Low Energy Proton Radiation Damage in p/n InP MOCVD Solar Cells

    Science.gov (United States)

    Rybicki, George; Weinberg, Irv; Scheiman, Dave; Vargas-Aburto, Carlos; Uribe, Roberto

    1995-01-01

    InP p(+)/n/n(+) solar cells, fabricated by metal organic chemical vapor deposition, (MOCVD) were irradiated with 0.2 MeV and 10 MeV protons to a fluence of 10(exp 13)/sq cm. The power output degradation, IV behavior, carrier concentration and defect concentration were observed at intermediate points throughout the irradiations. The 0.2 MeV proton-irradiated solar cells suffered much greater and more rapid degradation in power output than those irradiated with 10 MeV protons. The efficiency losses were accompanied by larger increases in the recombination currents in the 0.2 MeV proton-irradiated solar cells. The low energy proton irradiations also had a larger impact on the series resistance of the solar cells. Despite the radiation induced damage, the carrier concentration in the base of the solar cells showed no reduction after 10 MeV or 0.2 MeV proton irradiations and even increased during irradiation with 0.2 MeV protons. In a deep level transient spectroscopy (DLTS) study of the irradiated samples, the minority carrier defects H4 and H5 at E(sub v) + 0.33 and E(sub v) + 0.52 eV and the majority carrier defects E7 and El0 at E(sub c) - 0.39 and E(sub c) - 0.74 eV, were observed. The defect introduction rates for the 0.2 MeV proton irradiations were about 20 times higher than for the 10 MeV proton irradiations. The defect El0, observed here after irradiation, has been shown to act as a donor in irradiated n-type InP and may be responsible for obscuring carrier removal. The results of this study are consistent with the much greater damage produced by low energy protons whose limited range causes them to stop in the active region of the solar cell.

  11. Performance, defect behavior and carrier enhancement in low energy, proton irradiated p+nn+ InP solar cells

    Science.gov (United States)

    Weinberg, I.; Rybicki, G. C.; Vargas-Aburto, C.; Jain, R. K.; Scheiman, D.

    1994-01-01

    The highest AMO efficiency (19.1 percent) InP solar cell consisted of an n+pp+ structure epitaxially grown on a p+ InP substrate. However, the high cost and relative fragility of InP served as motivation for research efforts directed at heteroepitaxial growth of InP on more viable substrates. The highest AMO efficiency (13.7 percent) for this type of cell was achieved using a GaAs substrate. Considering only cost and fracture toughness, Si would be the preferred substrate. The fact that Si is a donor in InP introduces complexities which are necessary in order to avoid the formation of an efficiency limiting counterdiode. One method used to overcome this problem lies in employing an n+p+ tunnel junction in contact with the cell's p region. A simpler method consists of using an n+ substrate and processing the cell in the p+ nn+ configuration. This eliminates the need for a tunnel junction. Unfortunately, the p/n configuration has received relatively little attention the best cell with this geometry having achieved an efficiency of 17 percent. Irradiation of these homoepitaxial cells, with 1 Mev electrons, showed that they were slightly more radiation resistant than diffused junction n/p cells. Additional p/n InP cells have been processed by some activity aimed at diffusion. Currently, there has been some activity aimed at producing heteroepitaxial p+nn+ InP cells using n+ Ge substrates. Since, like Si, Ge is an n-dopant in InP, use of this configuration obviates the need for a tunnel junction. Obviously, before attempting to process heteroepitaxial cells, one must produce a reasonably good homoepitaxial cell. In the present case we focus our attention on homoepitaxially on an n+ Ge substrate.

  12. Wafer-scale self-organized InP nanopillars with controlled orientation for photovoltaic devices.

    Science.gov (United States)

    Sanatinia, Reza; Berrier, Audrey; Dhaka, Veer; Perros, Alexander P; Huhtio, Teppo; Lipsanen, Harri; Anand, Srinivasan

    2015-10-16

    A unique wafer-scale self-organization process for generation of InP nanopillars is demonstrated, which is based on maskless ion-beam etching (IBE) of InP developed to obtain the nanopillars, where the height, shape, and orientation of the nanopillars can be varied by controlling the processing parameters. The fabricated InP nanopillars exhibit broadband suppression of the reflectance, 'black InP,' a property useful for solar cells. The realization of a conformal p-n junction for carrier collection, in the fabricated solar cells, is achieved by a metalorganic vapor phase epitaxy (MOVPE) overgrowth step on the fabricated pillars. The conformal overgrowth retains the broadband anti-reflection property of the InP nanopillars, indicating the feasibility of this technology for solar cells. Surface passivation of the formed InP nanopillars using sulfur-oleylamine solution resulted in improved solar-cell characteristics. An open-circuit voltage of 0.71 V and an increase of 0.13 V compared to the unpassivated device were achieved.

  13. Heteroepitaxially grown InP solar cells

    International Nuclear Information System (INIS)

    Weinberg, I.; Swartz, C.K.; Brinker, D.J.; Wilt, D.M.

    1990-01-01

    Although they are significantly more radiation resistant than either Si or GaAs solar cells, their high wafer cost presents a barrier to the widespread use of InP solar cells in space. For this reason, the authors have initiated a program aimed at producing high efficiency, radiation resistant solar cells processed from InP heteroepitaxially grown on cheaper substrates. The authors' objective is to present the most recent results emanating from this program together with the results of their initial proton irradiations on these cells. This paper reports that InP cells were processed from a 4 micron layer of InP, grown by OMCVD on a silicon substrate, with a 0.5 micron buffer layer between the InP directly grown on a GaAs substrate. Initial feasibility studies, in a Lewis sponsored program at the Spire corporation, resulted in air mass zero efficiencies of 7.1% for the former cells and 9.1% for the latter. These initial low efficiencies are attributed to the high dislocation densities caused by lattice mismatch. The authors' preirradiation analysis indicates extremely low minority carrier diffusion lengths, in both cell base and emitter, and high values of both the diffusion and recombination components of the diode reverse saturation currents. Irradiation by 10 MeV protons, to a fluence of 10 13 cm -2 , resulted in relatively low degradation in cell efficiency, short circuit current and open circuit voltage

  14. Investigation on electrical properties of diffusive p-n junctions in InP and solid solutions of InAssub(x)Psub(1-x)

    International Nuclear Information System (INIS)

    Agaev, Ya.; Atabaev, Kh.; Gazakov, O.

    1977-01-01

    Diodes from InP and from solid solutions of InAssub(0.6)Psub(0.4), InAssub(0.5)Psub(0.5) were obtained by the diffusion of Zn. The voltage-current characteristic was measured at a direct current in the temperature range from 80 to 300 K. The rectification factor is 10 4 and 2.5 -3.0 x10 2 , respectively, for InP and InAssub(x)Psub(1-x) p-n junctions. The lifetime, the series resistance and resistance of the p-n junction at a zero bias were calculated from an analysis of the voltage-current characteristics

  15. Progress in InP solar cell research

    International Nuclear Information System (INIS)

    Weinberg, I.; Brinker, D.J.

    1988-01-01

    Progress, in the past year, in InP solar cell research is reviewed. Small area cells with AMO, total area efficiencies of 18.8 percent were produced by OMCVD and Ion Implantation. Larger area cells (2 and 4 sq cm) were processed on a production basis. One thousand of the 2 sq cm cells will be used to supply power to a small piggyback lunar orbiter scheduled for launch in February 1990. Laboratory tests of ITO/InP cells, under 10 MeV proton irradiation, indicate radiation resistance comparable to InP n/p homojunction cells. Computer modeling studies indicate that, for identical geometries and dopant concentrations, InP solar cells are significantly more radiation resistant than GaAs under 1 MeV electron irradiation. Additional computer modeling calculations were used to produce rectangular and circular InP concentrator cell designs for both the low concentration SLATS and higher concentration Cassegrainian Concentrators

  16. InP Solar Cells and their Flight Experiments

    OpenAIRE

    TAKAHASHI, Keiji; YAMAGUCHI, Masafumi; TAKAMOTO, Tatsuya; IKEGAMI, Shingo; OHNISHI, Akira; HAYASHI, Tomonao; USHIROKAWA, Akio; KOHBATA, Masahiko; ARAI, Hidetoshi; HASHIMOTO, Katsumasa; ORH, Takeshi; OKAZAKI, Hitoshi; TAKAMURA, Hideto; URA, Mitsuru; OHMORI, Masamichi

    1992-01-01

    We have developed high-efficiency homojunction 1 cm × 2 cm InP space solar cells by diffusing In_2S_3 into p type InP substrates and investigated their fundamental characteristics such as electrical and mechnical characteristics and thermal properties. On the radiation resistant mechanism of InP cells, we have studied InP cells fabricated at NTT Laboratories and found superior properties such as room temperture annealing and minority carrier injection enhanced annealing phenomena for radiatio...

  17. Workshop on Heteroepitaxial InP Solar Cells

    Science.gov (United States)

    Weinberg, I.; Walters, R. W.

    1993-01-01

    In a generic sense, the justification for any sort of InP solar cell research applies, i.e. to take advantage of the inherently high radiation resistance and efficiency of InP solar cells. To be more specific, the approach is justified by its potential for significant cost reduction and the availability of greatly increased cell area afforded by substrates such as Si and Ge. The use of substrates, such as the latter two, would result in increased ruggedness, ease of handling, and improved manufacturability. The use of more rugged substrates would lead to a greatly increased capability for cell thinning leading to the desirable feature of reduced array weight.

  18. High-efficiency, deep-junction, epitaxial InP solar cells on (100) and (111)B InP substrates

    Science.gov (United States)

    Venkatasubramanian, R.; Timmons, M. L.; Hutchby, J. A.; Walters, Robert J.; Summers, Geoffrey P.

    1994-01-01

    We report on the development and performance of deep-junction (approximately 0.25 micron), graded-emitter-doped, n(sup +)-p InP solar cells grown by metallorganic chemical vapor deposition (MOCVD). A novel, diffusion-transport process for obtaining lightly-doped p-type base regions of the solar cell is described. The I-V data and external quantum-efficiency response of these cells are presented. The best active-area AMO efficiency for these deep-junction cells on (100)-oriented InP substrates is 16.8 percent, with a J(sub SC) of 31.8 mA/sq cm, a V(sub OC) of 0.843 V, and a fill-factor of 0.85. By comparison, the best cell efficiency on the (111)B-oriented InP substrates was 15.0 percent. These efficiency values for deep-junction cells are encouraging and compare favorably with performance of thin-emitter (0.03 micron) epitaxial cells as well as that of deep-emitter diffused cells. The cell performance and breakdown voltage characteristics of a batch of 20 cells on each of the orientations are presented, indicating the superior breakdown voltage properties and other characteristics of InP cells on the (111)B orientation. Spectral response, dark I-V data, and photoluminescence (PL) measurements on the InP cells are presented with an analysis on the variation in J(sub SC) and V(sub OC) of the cells. It is observed, under open-circuit conditions, that lower-V(sub OC) cells exhibit higher band-edge PL intensity for both the (100) and (111)B orientations. This anomalous behavior suggests that radiative recombination in the heavily-doped n(sup +)-InP emitter may be detrimental to achieving higher V(sub OC) in n(sup +)-p InP solar cells.

  19. High conversion efficiency and high radiation resistance InP solar cells

    International Nuclear Information System (INIS)

    Yamamoto, Akio; Itoh, Yoshio; Yamaguchi, Masafumi

    1987-01-01

    The fabrication of homojunction InP solar cells has been studied using impurity thermal diffusion, organometallic vapor phase epitaxy (OMVPE) and liquid phase epitaxy (LPE), and is discussed in this paper. Conversion efficiencies exceeding 20 % (AM1.5) are attained. These are the most efficient results ever reported for InP cells, and are comparable to those for GaAs cells. Electron and γ-ray irradiation studies have also been conducted for fabricated InP cells. The InP cells were found to have higher radiation resistance than GaAs cells. Through these studies, it has been demonstrated that the InP cells have excellent potential for space application. (author)

  20. Ultrathin film, high specific power InP solar cells on flexible plastic substrates

    International Nuclear Information System (INIS)

    Shiu, K.-T.; Zimmerman, Jeramy; Wang Hongyu; Forrest, Stephen R.

    2009-01-01

    We demonstrate ultrathin-film, single-crystal InP Schottky-type solar cells mounted on flexible plastic substrates. The lightly p-doped InP cell is grown epitaxially on an InP substrate via gas source molecular beam epitaxy. The InP substrate is removed via selective chemical wet-etching after the epitaxial layers are cold-welded to a 25 μm thick Kapton sheet, followed by the deposition of an indium tin oxide top contact that forms the Schottky barrier with InP. The power conversion efficiency under 1 sun is 10.2±1.0%, and its specific power is 2.0±0.2 kW/kg. The ultrathin-film solar cells can tolerate both tensile and compressive stress by bending over a <1 cm radius without damage.

  1. High Efficiency InP Solar Cells from Low Toxicity Tertiarybutylphosphine

    Science.gov (United States)

    Hoffman, Richard W., Jr.; Fatemi, Navid S.; Wilt, David M.; Jenkins, Phillip P.; Brinker, David J.; Scheiman, David A.

    1994-01-01

    Large scale manufacture of phosphide based semiconductor devices by organo-metallic vapor phase epitaxy (OMVPE) typically requires the use of highly toxic phosphine. Advancements in phosphine substitutes have identified tertiarybutylphosphine (TBP) as an excellent precursor for OMVPE of InP. High quality undoped and doped InP films were grown using TBP and trimethylindium. Impurity doped InP films were achieved utilizing diethylzinc and silane for p and n type respectively. 16 percent efficient solar cells under air mass zero, one sun intensity were demonstrated with Voc of 871 mV and fill factor of 82.6 percent. It was shown that TBP could replace phosphine, without adversely affecting device quality, in OMVPE deposition of InP thus significantly reducing toxic gas exposure risk.

  2. Efficiency enhancement of InP nanowire solar cells by surface cleaning

    NARCIS (Netherlands)

    Cui, Y.; Wang, J.; Plissard, S.R.; Cavalli, A.; Vu, T.T.T.; Veldhoven, van P.J.; Gao, L.; Trainor, M.J.; Verheijen, M.A.; Haverkort, J.E.M.; Bakkers, E.P.A.M.

    2013-01-01

    We demonstrate an efficiency enhancement of an InP nanowire (NW) axial p–n junction solar cell by cleaning the NW surface. NW arrays were grown with in situ HCl etching on an InP substrate patterned by nanoimprint lithography, and the NWs surfaces were cleaned after growth by piranha etching. We

  3. InP tunnel junction for InGaAs/InP tandem solar cells

    Science.gov (United States)

    Vilela, M. F.; Freundlich, A.; Bensaoula, A.; Medelci, N.; Renaud, P.

    1995-01-01

    Chemical beam epitaxy (CBE) has been shown to allow the growth of high quality materials with reproducible complex compositional and doping profiles. The main advantage of CBE compared to metalorganic chemical vapor deposition (MOCVD), the most popular technique for InP-based photovoltaic device fabrication, is the ability to grow high purity epilayers at much lower temperatures (450-530 C). We have previously shown that CBE is perfectly suited toward the fabrication of complex photovoltaic devices such as InP/InGaAs monolithically integrated tandem solar cells, because its low process temperature preserves the electrical characteristics of the InGaAs tunnel junction commonly used as an ohmic interconnect. In this work using CBE for the fabrication of optically transparent (with respect to the bottom cell) InP tunnel diodes is demonstrated. Epitaxial growth were performed in a Riber CBE 32 system using PH3 and TMIn as III and V precursors. Solid Be (p-type) and Si (n-type) have been used as doping sources, allowing doping levels up to 2 x 10(exp -19)/cu cm and 1 x 10(exp -19)/cu cm for n and p type respectively. The InP tunnel junction characteristics and the influence of the growth's conditions (temperature, growth rate) over its performance have been carefully investigated. InP p(++)/n(++) tunnel junction with peak current densities up to 1600 A/sq cm and maximum specific resistivities (V(sub p)/I(sub p) - peak voltage to peak current ratio) in the range of 10(exp -4) Omega-sq cm were obtained. The obtained peak current densities exceed the highest results previously reported for their lattice matched counterparts, In(0.53)Ga( 0.47)As and should allow the realization of improved minimal absorption losses in the interconnect InP/InGaAs tandem devices for Space applications. Owing to the low process temperature required for the top cell, these devices exhibit almost no degradation of its characteristics after the growth of subsequent thick InP layer suggesting

  4. Radiation effects in heteroepitaxial InP solar cells

    Science.gov (United States)

    Weinberg, I.; Curtis, H. B.; Swartz, C. K.; Brinker, D. J.; Vargas-Aburto, C.

    1993-01-01

    Heteroepitaxial InP solar cells, with GaAs substrates, were irradiated by 0.5 and 3 MeV protons and their performance, temperature dependency, and carrier removal rates determined as a function of fluence. The radiation resistance of the present cells was significantly greater than that of non-heteroepitaxial InP cells at both proton energies. A clear difference in the temperature dependency of V(sub oc), was observed between heteroepitaxial and homoepitaxial InP cells. The analytically predicted dependence of dV(sub oc)/dT on Voc was confirmed by the fluence dependence of these quantities. Carrier removal was observed to increase with decreasing proton energy. The results obtained for performance and temperature dependency were attributed to the high dislocation densities present in the heteroepitaxial cells while the energy dependence of carrier removal was attributed to the energy dependence of proton range.

  5. InP solar cell with window layer

    Science.gov (United States)

    Jain, Raj K. (Inventor); Landis, Geoffrey A. (Inventor)

    1994-01-01

    The invention features a thin light transmissive layer of the ternary semiconductor indium aluminum arsenide (InAlAs) as a front surface passivation or 'window' layer for p-on-n InP solar cells. The window layers of the invention effectively reduce front surface recombination of the object semiconductors thereby increasing the efficiency of the cells.

  6. Enhanced monolayer MoS2/InP heterostructure solar cells by graphene quantum dots

    Science.gov (United States)

    Wang, Peng; Lin, Shisheng; Ding, Guqiao; Li, Xiaoqiang; Wu, Zhiqian; Zhang, Shengjiao; Xu, Zhijuan; Xu, Sen; Lu, Yanghua; Xu, Wenli; Zheng, Zheyang

    2016-04-01

    We demonstrate significantly improved photovoltaic response of monolayer molybdenum disulfide (MoS2)/indium phosphide (InP) van der Waals heterostructure induced by graphene quantum dots (GQDs). Raman and photoluminescence measurements indicate that effective charge transfer takes place between GQDs and MoS2, which results in n-type doping of MoS2. The doping effect increases the barrier height at the MoS2/InP heterojunction, thus the averaged power conversion efficiency of MoS2/InP solar cells is improved from 2.1% to 4.1%. The light induced doping by GQD provides a feasible way for developing more efficient MoS2 based heterostructure solar cells.

  7. Investigation of the open-circuit voltage in wide-bandgap InGaP-host InP quantum dot intermediate-band solar cells

    Science.gov (United States)

    Aihara, Taketo; Tayagaki, Takeshi; Nagato, Yuki; Okano, Yoshinobu; Sugaya, Takeyoshi

    2018-04-01

    To analyze the open-circuit voltage (V oc) in intermediate-band solar cells, we investigated the current-voltage characteristics in wide-bandgap InGaP-based InP quantum dot (QD) solar cells. From the temperature dependence of the current-voltage curves, we show that the V oc in InP QD solar cells increases with decreasing temperature. We use a simple diode model to extract V oc at the zero-temperature limit, V 0, and the temperature coefficient C of the solar cells. Our results show that, while the C of InP QD solar cells is slightly larger than that of the reference InGaP solar cells, V 0 significantly decreases and coincides with the bandgap energy of the InP QDs rather than that of the InGaP host. This V 0 indicates that the V oc reduction in the InP QD solar cells is primarily caused by the breaking of the Fermi energy separation between the QDs and the host semiconductor in intermediate-band solar cells, rather than by enhanced carrier recombination.

  8. Radiation hardening of InP solar cells for space applications

    International Nuclear Information System (INIS)

    Vilela, M. F.; Freundlich, A.; Monier, C.; Newman, F.; Aguilar, L.

    1998-01-01

    The aim of this work is to develop a radiation resistant thin InP-based solar cells for space applications on more mechanically resistant, lighter, and cheaper substrates. In this paper, we present the development of a p + /nn + InP-based solar cell structures with very thin emitter and base layers. A thin emitter helps to increase the collection of carriers generated by high energy incident photons from the solar spectrum. The use of a thin n base structure should improve the radiation resistance of this already radiation resistant technology. A remarkable improvement of high energy photons response is shown for InP solar cells with emitters 400 A thick

  9. Understanding InP Nanowire Array Solar Cell Performance by Nanoprobe-Enabled Single Nanowire Measurements.

    Science.gov (United States)

    Otnes, Gaute; Barrigón, Enrique; Sundvall, Christian; Svensson, K Erik; Heurlin, Magnus; Siefer, Gerald; Samuelson, Lars; Åberg, Ingvar; Borgström, Magnus T

    2018-05-09

    III-V solar cells in the nanowire geometry might hold significant synthesis-cost and device-design advantages as compared to thin films and have shown impressive performance improvements in recent years. To continue this development there is a need for characterization techniques giving quick and reliable feedback for growth development. Further, characterization techniques which can improve understanding of the link between nanowire growth conditions, subsequent processing, and solar cell performance are desired. Here, we present the use of a nanoprobe system inside a scanning electron microscope to efficiently contact single nanowires and characterize them in terms of key parameters for solar cell performance. Specifically, we study single as-grown InP nanowires and use electron beam induced current characterization to understand the charge carrier collection properties, and dark current-voltage characteristics to understand the diode recombination characteristics. By correlating the single nanowire measurements to performance of fully processed nanowire array solar cells, we identify how the performance limiting parameters are related to growth and/or processing conditions. We use this understanding to achieve a more than 7-fold improvement in efficiency of our InP nanowire solar cells, grown from a different seed particle pattern than previously reported from our group. The best cell shows a certified efficiency of 15.0%; the highest reported value for a bottom-up synthesized InP nanowire solar cell. We believe the presented approach have significant potential to speed-up the development of nanowire solar cells, as well as other nanowire-based electronic/optoelectronic devices.

  10. InP tunnel junctions for InP/InGaAs tandem solar cells

    Science.gov (United States)

    Vilela, Mauro F.; Freundlich, Alex; Renaud, P.; Medelci, N.; Bensaoula, A.

    1996-01-01

    We report, for the first time, an epitaxially grown InP p(+)/n(++) tunnel junction. A diode with peak current densities up to 1600 A/cm and maximum specific resistivities (Vp/Ip - peak voltage to peak current ratio) in the range of 10(exp -4)Omega cm(exp 2) is obtained. This peak current density is comparable to the highest results previously reported for lattice matched In(0.53)Ga(0.47)As tunnel junctions. Both results were obtained using chemical beam epitaxy (CBE). In this paper we discuss the electrical characteristics of these tunnel diodes and how the growth conditions influence them.

  11. GaAsPN-based PIN solar cells MBE-grown on GaP substrates: toward the III-V/Si tandem solar cell

    Science.gov (United States)

    Da Silva, M.; Almosni, S.; Cornet, C.; Létoublon, A.; Levallois, C.; Rale, P.; Lombez, L.; Guillemoles, J.-F.; Durand, O.

    2015-03-01

    GaAsPN semiconductors are promising material for the elaboration of high efficiencies tandem solar cells on silicon substrates. GaAsPN diluted nitride alloy is studied as the top junction material due to its perfect lattice matching with the Si substrate and its ideal bandgap energy allowing a perfect current matching with the Si bottom cell. We review our recent progress in materials development of the GaAsPN alloy and our recent studies of some of the different building blocks toward the elaboration of a PIN solar cell. A lattice matched (with a GaP(001) substrate, as a first step toward the elaboration on a Si substrate) 1μm-thick GaAsPN alloy has been grown by MBE. After a post-growth annealing step, this alloy displays a strong absorption around 1.8-1.9 eV, and efficient photoluminescence at room temperature suitable for the elaboration of the targeted solar cell top junction. Early stage GaAsPN PIN solar cells prototypes have been grown on GaP (001) substrates, with 2 different absorber thicknesses (1μm and 0.3μm). The external quantum efficiencies and the I-V curves show that carriers have been extracted from the GaAsPN alloy absorbers, with an open-circuit voltage of 1.18 V, while displaying low short circuit currents meaning that the GaAsPN structural properties needs a further optimization. A better carrier extraction has been observed with the absorber displaying the smallest thickness, which is coherent with a low carriers diffusion length in our GaAsPN compound. Considering all the pathways for improvement, the efficiency obtained under AM1.5G is however promising.

  12. Multiple growths of epitaxial lift-off solar cells from a single InP substrate

    International Nuclear Information System (INIS)

    Lee, Kyusang; Shiu, Kuen-Ting; Zimmerman, Jeramy D.; Forrest, Stephen R.; Renshaw, Christopher K.

    2010-01-01

    We demonstrate multiple growths of flexible, thin-film indium tin oxide-InP Schottky-barrier solar cells on a single InP wafer via epitaxial lift-off (ELO). Layers that protect the InP parent wafer surface during the ELO process are subsequently removed by selective wet-chemical etching, with the active solar cell layers transferred to a thin, flexible plastic host substrate by cold welding at room temperature. The first- and second-growth solar cells exhibit no performance degradation under simulated Atmospheric Mass 1.5 Global (AM 1.5G) illumination, and have a power conversion efficiency of η p =14.4±0.4% and η p =14.8±0.2%, respectively. The current-voltage characteristics for the solar cells and atomic force microscope images of the substrate indicate that the parent wafer is undamaged, and is suitable for reuse after ELO and the protection-layer removal processes. X-ray photoelectron spectroscopy, reflection high-energy electron diffraction observation, and three-dimensional surface profiling show a surface that is comparable or improved to the original epiready wafer following ELO. Wafer reuse over multiple cycles suggests that high-efficiency; single-crystal thin-film solar cells may provide a practical path to low-cost solar-to-electrical energy conversion.

  13. 19.2% Efficient InP Heterojunction Solar Cell with Electron-Selective TiO2 Contact.

    Science.gov (United States)

    Yin, Xingtian; Battaglia, Corsin; Lin, Yongjing; Chen, Kevin; Hettick, Mark; Zheng, Maxwell; Chen, Cheng-Ying; Kiriya, Daisuke; Javey, Ali

    2014-12-17

    We demonstrate an InP heterojunction solar cell employing an ultrathin layer (∼10 nm) of amorphous TiO 2 deposited at 120 °C by atomic layer deposition as the transparent electron-selective contact. The TiO 2 film selectively extracts minority electrons from the conduction band of p-type InP while blocking the majority holes due to the large valence band offset, enabling a high maximum open-circuit voltage of 785 mV. A hydrogen plasma treatment of the InP surface drastically improves the long-wavelength response of the device, resulting in a high short-circuit current density of 30.5 mA/cm 2 and a high power conversion efficiency of 19.2%.

  14. An Efficient and Effective Design of InP Nanowires for Maximal Solar Energy Harvesting.

    Science.gov (United States)

    Wu, Dan; Tang, Xiaohong; Wang, Kai; He, Zhubing; Li, Xianqiang

    2017-11-25

    Solar cells based on subwavelength-dimensions semiconductor nanowire (NW) arrays promise a comparable or better performance than their planar counterparts by taking the advantages of strong light coupling and light trapping. In this paper, we present an accurate and time-saving analytical design for optimal geometrical parameters of vertically aligned InP NWs for maximal solar energy absorption. Short-circuit current densities are calculated for each NW array with different geometrical dimensions under solar illumination. Optimal geometrical dimensions are quantitatively presented for single, double, and multiple diameters of the NW arrays arranged both squarely and hexagonal achieving the maximal short-circuit current density of 33.13 mA/cm 2 . At the same time, intensive finite-difference time-domain numerical simulations are performed to investigate the same NW arrays for the highest light absorption. Compared with time-consuming simulations and experimental results, the predicted maximal short-circuit current densities have tolerances of below 2.2% for all cases. These results unambiguously demonstrate that this analytical method provides a fast and accurate route to guide high performance InP NW-based solar cell design.

  15. Single P-N junction tandem photovoltaic device

    Science.gov (United States)

    Walukiewicz, Wladyslaw [Kensington, CA; Ager, III, Joel W.; Yu, Kin Man [Lafayette, CA

    2011-10-18

    A single P-N junction solar cell is provided having two depletion regions for charge separation while allowing the electrons and holes to recombine such that the voltages associated with both depletion regions of the solar cell will add together. The single p-n junction solar cell includes an alloy of either InGaN or InAlN formed on one side of the P-N junction with Si formed on the other side in order to produce characteristics of a two junction (2J) tandem solar cell through only a single P-N junction. A single P-N junction solar cell having tandem solar cell characteristics will achieve power conversion efficiencies exceeding 30%.

  16. Summary of Workshop on InP: Status and Prospects

    Science.gov (United States)

    Walters, R. J.; Weinberg, I.

    1994-01-01

    The primary objective of most of the programs in InP solar cells is the development of the most radiation hard solar cell technology. In the workshop, it was generally agreed that the goal is a cell which displays high radiation tolerance in a radiation environment equivalent to a 1 MeV electron fluence of about 10(exp 16)/sq cm. Furthermore, it is desired that the radiation response of the cell be essentially flat out to this fluence - i.e. that the power output of the cell not decrease from its beginning of life (BOL) value in this radiation environment. It was also agreed in the workshop that the manufacturability of InP solar cells needs to be improved. In particular, since InP wafers are relatively dense and brittle, alternative substrates need to be developed. Research on hetero-epitaxial InP cells grown on Si, Ge, and GaAs substrates is currently underway. The ultimate goal is to develop hetero-epitaxial InP solar cells using a cheap, strong, and lightweight substrate.

  17. Correlations for damage in diffused-junction InP solar cells induced by electron and proton irradiation

    International Nuclear Information System (INIS)

    Yamaguchi, M.; Takamoto, T.; Taylor, S.J.; Walters, R.J.; Summers, G.P.; Flood, D.J.; Ohmori, M.

    1997-01-01

    The damage to diffused-junction n + -p InP solar cells induced by electron and proton irradiations over a wide range of energy from 0.5 to 3 MeV and 0.015 to 20 MeV, respectively, has been examined. The experimental electron and proton damage coefficients have been analyzed in terms of displacement damage dose, which is the product of the particle fluence and the calculated nonionizing energy loss [G. P. Summers, E. A. Burke, R. Shapiro, S. R. Messenger, and R. J. Walters, IEEE Trans. Nucl. Sci. 40, 1300 (1993).] Degradation of InP cells due to irradiation with electrons and protons with energies of more than 0.5 MeV show a single curve as a function of displacement damage dose. Based on the deep-level transient spectroscopy analysis, damage equivalence between electron and proton irradiation is discussed. InP solar cells are confirmed to be substantially more radiation resistant than Si and GaAs-on-Ge cells. copyright 1997 American Institute of Physics

  18. Nonepitaxial Thin-Film InP for Scalable and Efficient Photocathodes.

    Science.gov (United States)

    Hettick, Mark; Zheng, Maxwell; Lin, Yongjing; Sutter-Fella, Carolin M; Ager, Joel W; Javey, Ali

    2015-06-18

    To date, some of the highest performance photocathodes of a photoelectrochemical (PEC) cell have been shown with single-crystalline p-type InP wafers, exhibiting half-cell solar-to-hydrogen conversion efficiencies of over 14%. However, the high cost of single-crystalline InP wafers may present a challenge for future large-scale industrial deployment. Analogous to solar cells, a thin-film approach could address the cost challenges by utilizing the benefits of the InP material while decreasing the use of expensive materials and processes. Here, we demonstrate this approach, using the newly developed thin-film vapor-liquid-solid (TF-VLS) nonepitaxial growth method combined with an atomic-layer deposition protection process to create thin-film InP photocathodes with large grain size and high performance, in the first reported solar device configuration generated by materials grown with this technique. Current-voltage measurements show a photocurrent (29.4 mA/cm(2)) and onset potential (630 mV) approaching single-crystalline wafers and an overall power conversion efficiency of 11.6%, making TF-VLS InP a promising photocathode for scalable and efficient solar hydrogen generation.

  19. Characteristics of withstanding radiation damage of InP crystals and devices

    International Nuclear Information System (INIS)

    Yamaguchi, Masafumi; Ando, Koshi

    1988-01-01

    Recently, the authors discovered that the characteristics of with standing radiation damage of InP crystals and devices (solar cells) are superior to those of Si and GaAs crystals and devices. Also the restoration phenomena at room temperature of radiation deterioration and the accelerated anneal phenomena by light irradiation and the injection of other minority, carriers in InP system devices were found. Such excellent characteristics suggested that InP devices are promising for the use in space. In this paper, taking an example of solar cells, the radiation resistance characteristics and their mechanism of InP crystals and devices are reported, based on the results of analysis by deep level transient spectroscopy and others. In InP solar cells, the high efficiency of photoelectric conversion was maintained even in the high dose irradiation of 1 MeV electron beam. As the carrier concentration in InP crystals is higher, they are stronger against radiation. With the increase of carrier concentration, the rate of anneal of radiation deterioration at room temperature increased. The accelerated anneal effect by minority carrier injection was remarkable in n + -p junction cells. The excellent characteristics of InP crystals are due to the formation of Frenkel defects of P and their instability. (K.I.)

  20. Wafer-scale self-organized InP nanopillars with controlled orientation for photovoltaic devices

    International Nuclear Information System (INIS)

    Sanatinia, Reza; Berrier, Audrey; Anand, Srinivasan; Dhaka, Veer; Perros, Alexander P; Huhtio, Teppo; Lipsanen, Harri

    2015-01-01

    A unique wafer-scale self-organization process for generation of InP nanopillars is demonstrated, which is based on maskless ion-beam etching (IBE) of InP developed to obtain the nanopillars, where the height, shape, and orientation of the nanopillars can be varied by controlling the processing parameters. The fabricated InP nanopillars exhibit broadband suppression of the reflectance, ‘black InP,’ a property useful for solar cells. The realization of a conformal p–n junction for carrier collection, in the fabricated solar cells, is achieved by a metalorganic vapor phase epitaxy (MOVPE) overgrowth step on the fabricated pillars. The conformal overgrowth retains the broadband anti-reflection property of the InP nanopillars, indicating the feasibility of this technology for solar cells. Surface passivation of the formed InP nanopillars using sulfur-oleylamine solution resulted in improved solar-cell characteristics. An open-circuit voltage of 0.71 V and an increase of 0.13 V compared to the unpassivated device were achieved. (paper)

  1. Performance, Defect Behavior and Carrier Enhancement in Low Energy, Proton Irradiated p(+)nn(+) InP Solar Cells

    Science.gov (United States)

    Weinberg, I.; Rybicki, G. C.; Vargas-Aburto, C.; Jain, R. K.; Scheiman, D.

    1994-01-01

    InP p(+)nn(+) cells, processed by MOCVD, were irradiated by 0.2 MeV protons and their performance and defect behavior observed to a maximum fluence of 10(exp 13)/sq cm. Their radiation induced degradation, over this fluence range, was considerably+less than observed for similarly irradiated, diffused junction n p InP cells. Significant degradation occurred in both the cell's emitter and base regions the least degradation occurring in the depletion region. A significant increase in series resistance occurs at the highest fluenc.e. Two majority carrier defect levels, E7 and E10, are observed by DLTS with activation energies at (E(sub C) - 0.39)eV and (E(sub C) - 0.74)eV respectively. The relative concentration of these defects differs considerably from that observed after 1 MeV electron irradiation. An increased carrier concentration in the cell's n-region was observed at the highest proton fluence, the change in carrier concentration being insignificant at the lower fluences. In agreement with previous results, for 1 and 1.5 MeV electron irradiated InP p(+)n junctions, the defect level E10 is attributed to a complex between zinc, diffused into the n-region from the zinc doped emitter, and a radiation induced defect. The latter is assumed to be either a phosphorus vacancy or interstitial. The increased, or enhanced carrier concentration is attributed to this complex acting as a donor.

  2. Radiation-hard, high efficiency InP solar cell and panel development

    International Nuclear Information System (INIS)

    Keavney, C.J.; Vernon, S.M.; Haven, V.E.; Nowlan, M.J.; Walters, R.J.; Slatter, R.L.; Summers, G.P.

    1991-01-01

    Indium phosphide solar cells with efficiencies over 19% (Air mass zero, 25 degrees C) and area of 4 cm 2 have been made and incorporated into prototype panels. The panels will be tested in space to confirm the high radiation resistance expected from InP solar cells, which makes the material attractive for space use, particularly in high-radiation orbits. Laboratory testing indicated an end-of-life efficiency of 15.5% after 10 15 1 MeV electrons, and 12% after 10 16 . These cells are made by metalorganic chemical vapor deposition, and have a shallow homojunction structure. The manufacturing process is amendable to scale-up to larger volumes; more than 200 cells were produced in the laboratory operation. Cell performance, radiation degradation, annealing behavior, and results of deep level transient spectroscopy studies are presented in this paper

  3. Enhanced Photocatalytic Reduction of CO2 to CO through TiO2 Passivation of InP in Ionic Liquids.

    Science.gov (United States)

    Zeng, Guangtong; Qiu, Jing; Hou, Bingya; Shi, Haotian; Lin, Yongjing; Hettick, Mark; Javey, Ali; Cronin, Stephen B

    2015-09-21

    A robust and reliable method for improving the photocatalytic performance of InP, which is one of the best known materials for solar photoconversion (i.e., solar cells). In this article, we report substantial improvements (up to 18×) in the photocatalytic yields for CO2 reduction to CO through the surface passivation of InP with TiO2 deposited by atomic layer deposition (ALD). Here, the main mechanisms of enhancement are the introduction of catalytically active sites and the formation of a pn-junction. Photoelectrochemical reactions were carried out in a nonaqueous solution consisting of ionic liquid, 1-ethyl-3-methylimidazolium tetrafluoroborate ([EMIM]BF4), dissolved in acetonitrile, which enables CO2 reduction with a Faradaic efficiency of 99% at an underpotential of +0.78 V. While the photocatalytic yield increases with the addition of the TiO2 layer, a corresponding drop in the photoluminescence intensity indicates the presence of catalytically active sites, which cause an increase in the electron-hole pair recombination rate. NMR spectra show that the [EMIM](+) ions in solution form an intermediate complex with CO2(-), thus lowering the energy barrier of this reaction. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Tunable absorption resonances in the ultraviolet for InP nanowire arrays.

    Science.gov (United States)

    Aghaeipour, Mahtab; Anttu, Nicklas; Nylund, Gustav; Samuelson, Lars; Lehmann, Sebastian; Pistol, Mats-Erik

    2014-11-17

    The ability to tune the photon absorptance spectrum is an attracting way of tailoring the response of devices like photodetectors and solar cells. Here, we measure the reflectance spectra of InP substrates patterned with arrays of vertically standing InP nanowires. Using the reflectance spectra, we calculate and analyze the corresponding absorptance spectra of the nanowires. We show that we can tune absorption resonances for the nanowire arrays into the ultraviolet by decreasing the diameter of the nanowires. When we compare our measurements with electromagnetic modeling, we generally find good agreement. Interestingly, the remaining differences between modeled and measured spectra are attributed to a crystal-phase dependence in the refractive index of InP. Specifically, we find indication of significant differences in the refractive index between the modeled zinc-blende InP nanowires and the measured wurtzite InP nanowires in the ultraviolet. We believe that such crystal-phase dependent differences in the refractive index affect the possibility to excite optical resonances in the large wavelength range of 345 InP nanowire-based solar cells and photodetectors.

  5. Molecular beam epitaxy of InP single junction and InP/In0.53Ga0.47As monolithically integrated tandem solar cells using solid phosphorous source material

    International Nuclear Information System (INIS)

    Delaney, A.; Chin, K.; Street, S.; Newman, F.; Aguilar, L.; Ignatiev, A.; Monier, C.; Velela, M.; Freundlich, A.

    1998-01-01

    This work reports the first InP solar cells, InP/In 0.53 Ga 0.47 As tandem solar cells and InP tunnel junctions to be grown using a solid phosphorous source cracker cell in a molecular beam epitaxy system. High p-type doping achieved with this system allowed for the development of InP tunnel junctions. These junctions which allow for improved current matching in subsequent monolithically integrated tandem devices also do not absorb photons which can be utilized in the InGaAs structure. Photocurrent spectral responses compared favorably to devices previously grown in a chemical beam epitaxy system. High resolution x-ray scans demonstrated good lattice matching between constituent parts of the tandem cell. AM0 efficiencies of both InP and InP/InGaAs tandem cells are reported

  6. Characteristic features of silicon multijunction solar cells with vertical p-n junctions

    International Nuclear Information System (INIS)

    Guk, E.G.; Nalet, T.A.; Shvarts, M.Z.; Shuman, V.B.

    1997-01-01

    A relatively simple technology (without photolithography) based on diffusion welding and ion-plasma deposition of an insulating coating has been developed for fabricating multijunction silicon solar cells with vertical p-n junctions. The effective collection factor for such structures is independent of the wavelength of the incident light in the wavelength range λ=340-1080 nm

  7. Thin-Film Solar Cells with InP Absorber Layers Directly Grown on Nonepitaxial Metal Substrates

    KAUST Repository

    Zheng, Maxwell

    2015-08-25

    The design and performance of solar cells based on InP grown by the nonepitaxial thin-film vapor-liquid-solid (TF-VLS) growth technique is investigated. The cell structure consists of a Mo back contact, p-InP absorber layer, n-TiO2 electron selective contact, and indium tin oxide transparent top electrode. An ex situ p-doping process for TF-VLS grown InP is introduced. Properties of the cells such as optoelectronic uniformity and electrical behavior of grain boundaries are examined. The power conversion efficiency of first generation cells reaches 12.1% under simulated 1 sun illumination with open-circuit voltage (VOC) of 692 mV, short-circuit current (JSC) of 26.9 mA cm-2, and fill factor (FF) of 65%. The FF of the cell is limited by the series resistances in the device, including the top contact, which can be mitigated in the future through device optimization. The highest measured VOC under 1 sun is 692 mV, which approaches the optically implied VOC of ≈795 mV extracted from the luminescence yield of p-InP. The design and performance of solar cells based on indium phosphide (InP) grown by the nonepitaxial thin-film vapor-liquid-solid growth technique is investigated. The cell structure consists of a Mo back contact, p-InP absorber layer, n-TiO2 electron selective contact, and an indium tin oxide transparent top electrode. The highest measured open circuit voltage (VOC) under 1 sun is 692 mV, which approaches the optically implied VOC of ≈795 mV extracted from the luminescence yield of p-InP.

  8. Proton irradiation induced defects in Cd and Zn doped InP

    International Nuclear Information System (INIS)

    Rybicki, G.C.; Williams, W.S.

    1993-01-01

    Proton irradiation induced defects in Zn and Cd doped InP have been studied by deep level transient spectroscopy, (DLTS). After 2 MeV proton irradiation the defects H4 and H5 were observed in lightly Zn doped InP, while the defects H3 and H5 were observed in more heavily Zn and Cd doped InP. The defect properties were not affected by the substitution of Cd for Zn, but the introduction rate of H5 was lower in Cd doped InP. The annealing rate of defects was also higher in Cd doped InP. The use of Cd doped InP may thus result in an InP solar cell with even greater radiation resistance

  9. Photovoltaic characteristics of diffused P/+N bulk GaAs solar cells

    Science.gov (United States)

    Borrego, J. M.; Keeney, R. P.; Bhat, I. B.; Bhat, K. N.; Sundaram, L. G.; Ghandhi, S. K.

    1982-01-01

    The photovoltaic characteristics of P(+)N junction solar cells fabricated on bulk GaAs by an open tube diffusion technique are described in this paper.Spectral response measurements were analyzed in detail and compared to a computer simulation in order to determine important material parameters. It is projected that proper optimization of the cell parameters can increase the efficiency of the cells from 12.2 percent to close to 20 percent.

  10. Performance of ultra high efficiency thin germanium p-n junction solar cells intended for solar thermophotovoltaic application

    Energy Technology Data Exchange (ETDEWEB)

    Vera, E S; Loferski, J J; Spitzer, M; Schewchun, J

    1981-01-01

    The theoretical upper limit conversion efficiency as a function of cell thickness and junction position is calculated for a germanium p-n junction solar cell intended for solar thermophotovoltaic energy conversion which incorporates minority carrier mirrors and optical mirrors on both the front and back boundaries of the active part of the device. The optical mirrors provide light confinement reducing the thickness required for optimum performance while minority carrier mirrors diminish surface recombination of carriers which seriously reduce short circuit current and limit open circuit voltage. The role of non-ideal optical and minority carrier mirrors and the effect of resistivity variations are studied. The calculations are conducted under conditions of high incident power (2-25 W/cm/sup 2/) which are encountered in solar thermophotovoltaic energy conversion systems. 14 refs.

  11. A numerical model of p-n junctions bordering on surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Altermatt, P.P.; Aberle, A.G.; Jianhua Zhao; Aihua Wang; Heiser, G. [University of New South Wales, Sydney (Australia). Centre for Photovolatic Engineering

    2002-10-01

    Many solar cell structures contain regions where the emitter p-n junction borders on the surface. If the surface is not well passivated, a large amount of recombination occurs in such regions. This type of recombination is influenced by the electrostatics of both the p-n junction and the surface, and hence it is different from the commonly described recombination phenomena occurring in the p-n junction within the bulk. We developed a two-dimensional model for the recombination mechanisms occurring in emitter p-n junctions bordering on surfaces. The model is validated by reproducing the experimental I-V curves of specially designed silicon solar cells. It is shown under which circumstances a poor surface passivation, near where the p-n junction borders on the surface, reduces the fill factor and the open-circuit voltage. The model can be applied to many other types of solar cells. (author)

  12. Hydrogen Passivation of Interstitial Zn Defects in Heteroepitaxial InP Cell Structures and Influence on Device Characteristics

    Science.gov (United States)

    Ringel, S. A.; Chatterjee, B.

    2004-01-01

    Hydrogen passivation of heteroepitaxial InP solar cells is of recent interest for deactivation of dislocations and other defects caused by the cell/substrate lattice mismatch that currently limit the photovoltaic performance of these devices. In this paper we present strong evidence that, in addition to direct hydrogen-dislocation interactions, hydrogen forms complexes with the high concentration of interstitial Zn defects present within the p(+) Zn-doped emitter of MOCVD-grown heteroepitaxial InP devices, resulting in a dramatic increase of the forward bias turn-on voltage by as much as 280 mV, from 680 mV to 960 mV. This shift is reproducible and thermally reversible and no such effect is observed for either n(+)p structures or homoepitaxial p(+)n structures grown under identical conditions. A combination of photoluminescence (PL), electrochemical C-V dopant profiling, SIMS and I-V measurements were performed on a set of samples having undergone a matrix of hydrogenation and post-hydrogenation annealing conditions to investigate the source of this voltage enhancement and confirm the expected role of interstitial Zn and hydrogen. A precise correlation between all measurements is demonstrated which indicates that Zn interstitials within the p(+) emitter and their interaction with hydrogen are indeed responsible for this device behavior.

  13. Photovoltaic characteristics of n(+)pp(+) InP solar cells grown by OMVPE

    Science.gov (United States)

    Tyagi, S.; Singh, K.; Bhimnathwala, H.; Ghandhi, S. K.; Borrego, J. M.

    1990-01-01

    The photovoltaic characteristics of n(+)/p/p(+) homojunction InP solar cells fabricated by organometallic vapor-phase epitaxy (OMVPE) are described. The cells are characterized by I-V, C-V and quantum efficiency measurements, and simulations are used to obtain various device and material parameters. The I-V characteristics show a high recombination rate in the depletion region; this is shown to be independent of the impurity used. It is shown that cadmium is easier to use as an acceptor for the p base and p(+) buffer and is therefore beneficial. The high quantum efficiency of 98 percent at long wavelengths measured in these cells indicates a very good collection efficiency in the base. The short-wavelength quantum efficiency is poor, indicating a high surface recombination.

  14. Radiation and temperature effects in gallium arsenide, indium phosphide, and silicon solar cells

    Science.gov (United States)

    Weinberg, I.; Swartz, C. K.; Hart, R. E., Jr.; Statler, R. L.

    1987-01-01

    The effects of radiation on performance are determined for both n+p and p+n GaAs and InP cells and for silicon n+p cells. It is found that the radiation resistance of InP is greater than that of both GaAs and Si under 1-MeV electron irradiation. For silicon, the observed decreased radiation resistance with decreased resistivity is attributed to the presence of a radiation-induced boron-oxygen defect. Comparison of radiation damage in both p+n and n+p GaAs cells yields a decreased radiation resistance for the n+p cell attributable to increased series resistance, decreased shunt resistance, and relatively greater losses in the cell's p-region. For InP, the n+p configuration is found to have greater radiation resistance than the p+n cell. The increased loss in this latter cell is attributed to losses in the cell's emitter region. Temperature dependency results are interpreted using a theoretical relation for dVoc/dT, which predicts that increased Voc should result in decreased numerical values for dPm/dT. The predicted correlation is observed for GaAs but not for InP, a result which is attributed to variations in cell processing.

  15. Comparative analysis of photovoltaic principles governing dye-sensitized solar cells and p-n junctions

    Science.gov (United States)

    Bisquert, Juan; Garcia-Canadas, Jorge; Mora-Sero, Ivan; Palomares, Emilio

    2004-02-01

    We discuss a generalized model for a solar cell, and the realization with heterogeneous photochemical photovoltaic converters such as the dye-sensitized solar cell. The different steps involved in the conversion of photon energy to electrical energy, indicate that a key point to consider is maintaining the separation of Fermi levels in the selective contacts to the absorber. In order to understand the irreversible processes limiting the efficient operation of the solar cell, it is necessary to obtain a precise description of the internal distribution of Fermi levels. We suggest the equivalent circuit as a central tool for obtaining such description, in relation with small perturbation measurement techniques. The fundamental steps of excitation and charge separation, and the losses by transport and charge transfer, can be represented by suitable circuit elements, and the overall circuit configuration indicates the operation of the selective contacts. The comparison of the equivalent circuits for heterogeneous dye solar cells and solid-state p-n junctions, shows the significant difference in the mechanisms of the selective contacts of these solar cells.

  16. When is an INP not an INP?

    Science.gov (United States)

    Simpson, Emma; Connolly, Paul; McFiggans, Gordon

    2016-04-01

    Processes such as precipitation and radiation depend on the concentration and size of different hydrometeors within clouds therefore it is important to accurately predict them in weather and climate models. A large fraction of clouds present in our atmosphere are mixed phase; contain both liquid and ice particles. The number of drops and ice crystals present in mixed phase clouds strongly depends on the size distribution of aerosols. Cloud condensation nuclei (CCN), a subset of atmospheric aerosol particles, are required for liquid drops to form in the atmosphere. These particles are ubiquitous in the atmosphere. To nucleate ice particles in mixed phase clouds ice nucleating particles (INP) are required. These particles are rarer than CCN. Here we investigate the case where CCN and INPs are in direct competition with each other for water vapour within a cloud. Focusing on the immersion and condensation modes of freezing (where an INP must be immersed within a liquid drop before it can freeze) we show that the presence of CCN can suppress the formation of ice. CCN are more hydrophilic than IN and as such are better able to compete for water vapour than, typically insoluble, INPs. Therefore water is more likely to condense onto a CCN than INP, leaving the INP without enough condensed water on it to be able to freeze in the immersion or condensation mode. The magnitude of this suppression effect strongly depends on a currently unconstrained quantity. Here we refer to this quantity as the critical mass of condensed water required for freezing, Mwc. Mwc is the threshold amount of water that must be condensed onto a INP before it can freeze in the immersion or condensation mode. Using the detailed cloud parcel model, Aerosol-Cloud-Precipiation-Interaction Model (ACPIM), developed at the University of Manchester we show that if only a small amount of water is required for freezing there is little suppression effect and if a large amount of water is required there is a

  17. A multiple p-n junction structure obtained from as-grown Czochralski silicon crystals by heat treatment - Application to solar cells

    Science.gov (United States)

    Chi, J. Y.; Gatos, H. C.; Mao, B. Y.

    1980-01-01

    Multiple p-n junctions have been prepared in as-grown Czochralski p-type silicon through overcompensation near the oxygen periodic concentration maxima by oxygen thermal donors generated during heat treatment at 450 C. Application of the multiple p-n-junction configuration to photovoltaic energy conversion has been investigated. A new solar-cell structure based on multiple p-n-junctions was developed. Theoretical analysis showed that a significant increase in collection efficiency over the conventional solar cells can be achieved.

  18. Optimization of the short-circuit current in an InP nanowire array solar cell through opto-electronic modeling.

    Science.gov (United States)

    Chen, Yang; Kivisaari, Pyry; Pistol, Mats-Erik; Anttu, Nicklas

    2016-09-23

    InP nanowire arrays with axial p-i-n junctions are promising devices for next-generation photovoltaics, with a demonstrated efficiency of 13.8%. However, the short-circuit current in such arrays does not match their absorption performance. Here, through combined optical and electrical modeling, we study how the absorption of photons and separation of the resulting photogenerated electron-hole pairs define and limit the short-circuit current in the nanowires. We identify how photogenerated minority carriers in the top n segment (i.e. holes) diffuse to the ohmic top contact where they recombine without contributing to the short-circuit current. In our modeling, such contact recombination can lead to a 60% drop in the short-circuit current. To hinder such hole diffusion, we include a gradient doping profile in the n segment to create a front surface barrier. This approach leads to a modest 5% increase in the short-circuit current, limited by Auger recombination with increased doping. A more efficient approach is to switch the n segment to a material with a higher band gap, like GaP. Then, a much smaller number of holes is photogenerated in the n segment, strongly limiting the amount that can diffuse and disappear into the top contact. For a 500 nm long top segment, the GaP approach leads to a 50% higher short-circuit current than with an InP top segment. Such a long top segment could facilitate the fabrication and contacting of nanowire array solar cells. Such design schemes for managing minority carriers could open the door to higher performance in single- and multi-junction nanowire-based solar cells.

  19. Wurtzite-Phased InP Micropillars Grown on Silicon with Low Surface Recombination Velocity.

    Science.gov (United States)

    Li, Kun; Ng, Kar Wei; Tran, Thai-Truong D; Sun, Hao; Lu, Fanglu; Chang-Hasnain, Connie J

    2015-11-11

    The direct growth of III-V nanostructures on silicon has shown great promise in the integration of optoelectronics with silicon-based technologies. Our previous work showed that scaling up nanostructures to microsize while maintaining high quality heterogeneous integration opens a pathway toward a complete photonic integrated circuit and high-efficiency cost-effective solar cells. In this paper, we present a thorough material study of novel metastable InP micropillars monolithically grown on silicon, focusing on two enabling aspects of this technology-the stress relaxation mechanism at the heterogeneous interface and the microstructure surface quality. Aberration-corrected transmission electron microscopy studies show that InP grows directly on silicon without any amorphous layer in between. A set of periodic dislocations was found at the heterointerface, relaxing the 8% lattice mismatch between InP and Si. Single crystalline InP therefore can grow on top of the fully relaxed template, yielding high-quality micropillars with diameters expanding beyond 1 μm. An interesting power-dependence trend of carrier recombination lifetimes was captured for these InP micropillars at room temperature, for the first time for micro/nanostructures. By simply combining internal quantum efficiency with carrier lifetime, we revealed the recombination dynamics of nonradiative and radiative portions separately. A very low surface recombination velocity of 1.1 × 10(3) cm/sec was obtained. In addition, we experimentally estimated the radiative recombination B coefficient of 2.0 × 10(-10) cm(3)/sec for pure wurtzite-phased InP. These values are comparable with those obtained from InP bulk. Exceeding the limits of conventional nanowires, our InP micropillars combine the strengths of both nanostructures and bulk materials and will provide an avenue in heterogeneous integration of III-V semiconductor materials onto silicon platforms.

  20. Lifetime measurements by open circuit voltage decay in GaAs and InP diodes

    International Nuclear Information System (INIS)

    Bhimnathwala, H.G.; Tyagi, S.D.; Bothra, S.; Ghandhi, S.K.; Borrego, J.M.

    1990-01-01

    Minority carrier lifetimes in the base of solar cells made in GaAs and InP are measured by open circuit voltage decay method. This paper describes the measurement technique and the conditions under which the minority carrier lifetimes can be measured. Minority carrier lifetimes ranging from 1.6 to 34 ns in InP of different doping concentrations are measured. A minority carrier lifetime of 6 ns was measured in n-type GaAs which agrees well with the lifetime of 5.7 ns measured by transient microwave reflection

  1. Radiation resistance and comparative performance of ITO/InP and n/p InP homojunction solar cells

    International Nuclear Information System (INIS)

    Weinberg, I.; Swartz, C.K.; Hart, R.E. Jr.; Coutts, T.J.

    1988-09-01

    The radiation resistance of ITO/InP cells processed by DC magnetron sputtering is compared to that of standard n/p InP and GaAs homojunction cells. After 20 MeV proton irradiations, it is found that the radiation resistance of the present ITO/InP cell is comparable to that of the n/p homojunction InP cell and that both InP cell types have radiation resistance significantly greater than GaAs. The relatively lower radiation resistance, observed at higher fluence, for the InP cell with the deepest junction depth, is attributed to losses in the cells emitter region. Diode parameters obtained from I sub sc - V sub oc plots, data from surface Raman spectroscopy, and determinations of surface conductivity types are used to investigate the configuration of the ITO/InP cells. It is concluded that thesee latter cells are n/p homojunctions, the n-region consisting of a disordered layer at the oxide semiconductor

  2. High brightness InP micropillars grown on silicon with Fermi level splitting larger than 1 eV.

    Science.gov (United States)

    Tran, Thai-Truong D; Sun, Hao; Ng, Kar Wei; Ren, Fan; Li, Kun; Lu, Fanglu; Yablonovitch, Eli; Chang-Hasnain, Constance J

    2014-06-11

    The growth of III-V nanowires on silicon is a promising approach for low-cost, large-scale III-V photovoltaics. However, performances of III-V nanowire solar cells have not yet been as good as their bulk counterparts, as nanostructured light absorbers are fundamentally challenged by enhanced minority carriers surface recombination rates. The resulting nonradiative losses lead to significant reductions in the external spontaneous emission quantum yield, which, in turn, manifest as penalties in the open-circuit voltage. In this work, calibrated photoluminescence measurements are utilized to construct equivalent voltage-current characteristics relating illumination intensities to Fermi level splitting ΔF inside InP microillars. Under 1 sun, we show that splitting can exceed ΔF ∼ 0.90 eV in undoped pillars. This value can be increased to values of ΔF ∼ 0.95 eV by cleaning pillar surfaces in acidic etchants. Pillars with nanotextured surfaces can yield splitting of ΔF ∼ 0.90 eV, even though they exhibit high densities of stacking faults. Finally, by introducing n-dopants, ΔF of 1.07 eV can be achieved due to a wider bandgap energy in n-doped wurzite InP, the higher brightness of doped materials, and the extraordinarily low surface recombination velocity of InP. This is the highest reported value for InP materials grown on a silicon substrate. These results provide further evidence that InP micropillars on silicon could be a promising material for low-cost, large-scale solar cells with high efficiency.

  3. CELULE FOTOVOLTAICE CU HOMOJONCŢIUNE DIN InP: REZULTATE ŞI COMPARĂRI

    Directory of Open Access Journals (Sweden)

    Vasile BOTNARIUC

    2016-12-01

    Full Text Available Au fost obţinute homojoncţiuni n-pInP cu strat intermediar p-InP crescut repetat prin metoda HVPE cu sau fără strat frontal nCdS şi au fost cercetate proprietăţile electrice şi fotoelectrice ale acestora. S-a constatat că depunerea stratului intermediar măreşte fotosensibilitatea homostructurilor cu 15…20%. Eficienţa energetică a CF cu structura n+CdS-n+InP-p-InP-p+InP constituie 13,5% pentru fluxul luminos incident de 100 mW×cm-2. Eficienţa CF cu heterostructura nCdS-pInP şi cu strat intermediar similar creşte cu 27%, în comparaţie cu CF cu homostructura n-p--pInP şi cu strat frontal nCdS, având valoarea de 17,3%. Se conturează posibilitatea reală de mărire a eficienţei CF de acest tip.FOTOVOLTAIC CELLS WITH HOMOJUNCTIONS IN InP: REZULTS AND COMPARISONSElectrical and photoelectrical properties of InP p-n homojunctions with an intermediate p-InP layer repeatedly grown by HVPE method, with and without frontal nCdS layer were produced and studied. It was found that the deposition of this intermediate p-InP layer increases the cells photosensitivity by 15 ... 20%. The solar energy conversion efficiency of photovoltaic cell (PC with n+CdS-n+InP-p-InP-p+InP structure is 13.5% at the illumination of 100 mW.cm-2. The efficiency of the PC based on nCdS-pInP heterostructure and an analogic intermediate layer increases to 27% compared with the PC based on n-p--pInP homostructure having a frontal nCdS layer has an efficiency of 17.3%. The possibility of increasing of the efficiency of this PC type is formulated.

  4. Indium phosphide solar cell research in the United States: Comparison with non-photovoltaic sources

    Science.gov (United States)

    Weinberg, I.; Swartz, C. K.; Hart, R. E., Jr.

    1989-01-01

    Highlights of the InP solar cell research program are presented. Homojunction cells with efficiencies approaching 19 percent are demonstrated, while 17 percent is achieved for ITO/InP cells. The superior radiation resistance of the two latter cell configurations over both Si and GaAs cells has been shown. InP cells aboard the LIPS3 satellite show no degradation after more than a year in orbit. Computed array specific powers are used to compare the performance of an InP solar cell array to solar dynamic and nuclear systems.

  5. Characterization of ion-irradiation-induced nanodot structures on InP surfaces by atom probe tomography.

    Science.gov (United States)

    Gnaser, Hubert; Radny, Tobias

    2015-12-01

    Surfaces of InP were bombarded by 1.9 keV Ar(+) ions under normal incidence. The total accumulated ion fluence the samples were exposed to was varied from 1 × 10(17) cm(-2) to 3 × 10(18)cm(-2) and ion flux densities f of (0.4-2) × 10(14) cm(-2) s(-1) were used. Nanodot structures were found to evolve on the surface from these ion irradiations, their dimensions however, depend on the specific bombardment conditions. The resulting surface morphology was examined by atomic force microscopy (AFM). As a function of ion fluence, the mean radius, height, and spacing of the dots can be fitted by power-law dependences. In order to determine possible local compositional changes in these nanostructures induced by ion impact, selected samples were prepared for atom probe tomography (APT). The results indicate that by APT the composition of individual InP nanodots evolving under ion bombardment could be examined with atomic spatial resolution. At the InP surface, the values of the In/P concentration ratio are distinctly higher over a distance of ~1 nm and amount to 1.3-1.8. However, several aspects critical for the analyses were identified: (i) because of the small dimensions of these nanostructures a successful tip preparation proved very challenging. (ii) The elemental compositions obtained from APT were found to be influenced pronouncedly by the laser pulse energy; typically, low energies result in the correct stoichiometry whereas high ones lead to an inhomogeneous evaporation from the tips and deviations from the nominal composition. (iii) Depending again on the laser energy, a prolific emission of Pn cluster ions was observed, with n ≤ 11. Copyright © 2015. Published by Elsevier B.V.

  6. Peptides for functionalization of InP semiconductors.

    Science.gov (United States)

    Estephan, Elias; Saab, Marie-belle; Larroque, Christian; Martin, Marta; Olsson, Fredrik; Lourdudoss, Sebastian; Gergely, Csilla

    2009-09-15

    The challenge is to achieve high specificity in molecular sensing by proper functionalization of micro/nano-structured semiconductors by peptides that reveal specific recognition for these structures. Here we report on surface modification of the InP semiconductors by adhesion peptides produced by the phage display technique. An M13 bacteriophage library has been used to screen 10(10) different peptides against the InP(001) and the InP(111) surfaces to finally isolate specific peptides for each orientation of the InP. MALDI-TOF/TOF mass spectrometry has been employed to study real affinity of the peptide towards the InP surfaces. The peptides serve for controlled placement of biotin onto InP to bind then streptavidin. Our Atomic Force Microscopy study revealed a total surface coverage of molecules when the InP surface was functionalized by its specific biotinylated peptide (YAIKGPSHFRPS). Finally, fluorescence microscopy has been employed to demonstrate the preferential attachment of the peptide onto a micro-patterned InP surface. Use of substrate specific peptides could present an alternative solution for the problems encountered in the actually existing sensing methods and molecular self-assembly due to the unwanted unspecific interactions.

  7. Background study for the pn-CCD detector of CERN Axion Solar Telescope

    CERN Document Server

    Cebrián, S; Kuster, M.; Beltran, B.; Gomez, H.; Hartmann, R.; Irastorza, I. G.; Kotthaus, R.; Luzon, G.; Morales, J.; Ruz, J.; Struder, L.; Villar, J. A.

    2007-01-01

    The CERN Axion Solar Telescope (CAST) experiment searches for axions from the Sun converted into photons with energies up to around 10 keV via the inverse Primakoff effect in the high magnetic field of a superconducting Large Hadron Collider (LHC) prototype magnet. A backside illuminated pn-CCD detector in conjunction with an X-ray mirror optics is one of the three detectors used in CAST to register the expected photon signal. Since this signal is very rare and different background components (environmental gamma radiation, cosmic rays, intrinsic radioactive impurities in the set-up, ...) entangle it, a detailed study of the detector background has been undertaken with the aim to understand and further reduce the background level of the detector. The analysis is based on measured data taken during the Phase I of CAST and on Monte Carlo simulations of different background components. This study will show that the observed background level (at a rate of (8.00+-0.07)10^-5 counts/cm^2/s/keV between 1 and 7 keV) s...

  8. Thermal diffusion in nanostructured porous InP

    International Nuclear Information System (INIS)

    Srinivasan, R.; Ramachandran, K.

    2008-01-01

    Nanostructured porous InP samples were prepared by electrochemical anodic dissolution of InP for various current densities and etching periods. The samples were characterized by SEM and photoluminescence (PL) where a blue shift was observed in PL. Thermal properties studies by photoacoustic (PA) spectroscopy revealed one order decrease in thermal conductivity of porous InP compared to the bulk. Further it is shown that the thermal conductivity of porous InP decreases with decrease in size of the particles. (author)

  9. Solar energy: photovoltaics

    International Nuclear Information System (INIS)

    Goetzberger, A.; Voss, B.; Knobloch, J.

    1994-01-01

    This textbooks covers the following topics: foundations of photovoltaics, solar energy, P-N junctions, physics of solar cells, high-efficiency solar cells, technology of Si solar cells, other solar cells, photovoltaic applications. (orig.)

  10. Growth of InP directly on Si by corrugated epitaxial lateral overgrowth

    International Nuclear Information System (INIS)

    Metaferia, Wondwosen; Kataria, Himanshu; Sun, Yan-Ting; Lourdudoss, Sebastian

    2015-01-01

    In an attempt to achieve an InP–Si heterointerface, a new and generic method, the corrugated epitaxial lateral overgrowth (CELOG) technique in a hydride vapor phase epitaxy reactor, was studied. An InP seed layer on Si (0 0 1) was patterned into closely spaced etched mesa stripes, revealing the Si surface in between them. The surface with the mesa stripes resembles a corrugated surface. The top and sidewalls of the mesa stripes were then covered by a SiO 2 mask after which the line openings on top of the mesa stripes were patterned. Growth of InP was performed on this corrugated surface. It is shown that growth of InP emerges selectively from the openings and not on the exposed silicon surface, but gradually spreads laterally to create a direct interface with the silicon, hence the name CELOG. We study the growth behavior using growth parameters. The lateral growth is bounded by high index boundary planes of {3 3 1} and {2 1 1}. The atomic arrangement of these planes, crystallographic orientation dependent dopant incorporation and gas phase supersaturation are shown to affect the extent of lateral growth. A lateral to vertical growth rate ratio as large as 3.6 is achieved. X-ray diffraction studies confirm substantial crystalline quality improvement of the CELOG InP compared to the InP seed layer. Transmission electron microscopy studies reveal the formation of a direct InP–Si heterointerface by CELOG without threading dislocations. While CELOG is shown to avoid dislocations that could arise due to the large lattice mismatch (8%) between InP and Si, staking faults could be seen in the layer. These are probably created by the surface roughness of the Si surface or SiO 2 mask which in turn would have been a consequence of the initial process treatments. The direct InP–Si heterointerface can find applications in high efficiency and cost-effective Si based III–V semiconductor multijunction solar cells and optoelectronics integration. (paper)

  11. Single-nanowire, low-bandgap hot carrier solar cells with tunable open-circuit voltage

    Science.gov (United States)

    Limpert, Steven; Burke, Adam; Chen, I.-Ju; Anttu, Nicklas; Lehmann, Sebastian; Fahlvik, Sofia; Bremner, Stephen; Conibeer, Gavin; Thelander, Claes; Pistol, Mats-Erik; Linke, Heiner

    2017-10-01

    Compared to traditional pn-junction photovoltaics, hot carrier solar cells offer potentially higher efficiency by extracting work from the kinetic energy of photogenerated ‘hot carriers’ before they cool to the lattice temperature. Hot carrier solar cells have been demonstrated in high-bandgap ferroelectric insulators and GaAs/AlGaAs heterostructures, but so far not in low-bandgap materials, where the potential efficiency gain is highest. Recently, a high open-circuit voltage was demonstrated in an illuminated wurtzite InAs nanowire with a low bandgap of 0.39 eV, and was interpreted in terms of a photothermoelectric effect. Here, we point out that this device is a hot carrier solar cell and discuss its performance in those terms. In the demonstrated devices, InP heterostructures are used as energy filters in order to thermoelectrically harvest the energy of hot electrons photogenerated in InAs absorber segments. The obtained photovoltage depends on the heterostructure design of the energy filter and is therefore tunable. By using a high-resistance, thermionic barrier, an open-circuit voltage is obtained that is in excess of the Shockley-Queisser limit. These results provide generalizable insight into how to realize high voltage hot carrier solar cells in low-bandgap materials, and therefore are a step towards the demonstration of higher efficiency hot carrier solar cells.

  12. Low-Cost High-Efficiency Solar Cells with Wafer Bonding and Plasmonic Technologies

    Science.gov (United States)

    Tanake, Katsuaki

    We fabricated a direct-bond interconnected multijunction solar cell, a two-terminal monolithic GaAs/InGaAs dual-junction cell, to demonstrate a proof-of-principle for the viability of direct wafer bonding for solar cell applications. The bonded interface is a metal-free n+GaAs/n +InP tunnel junction with highly conductive Ohmic contact suitable for solar cell applications overcoming the 4% lattice mismatch. The quantum efficiency spectrum for the bonded cell was quite similar to that for each of unbonded GaAs and InGaAs subcells. The bonded dual-junction cell open-circuit voltage was equal to the sum of the unbonded subcell open-circuit voltages, which indicates that the bonding process does not degrade the cell material quality since any generated crystal defects that act as recombination centers would reduce the open-circuit voltage. Also, the bonded interface has no significant carrier recombination rate to reduce the open circuit voltage. Engineered substrates consisting of thin films of InP on Si handle substrates (InP/Si substrates or epitaxial templates) have the potential to significantly reduce the cost and weight of compound semiconductor solar cells relative to those fabricated on bulk InP substrates. InGaAs solar cells on InP have superior performance to Ge cells at photon energies greater than 0.7 eV and the current record efficiency cell for 1 sun illumination was achieved using an InGaP/GaAs/InGaAs triple junction cell design with an InGaAs bottom cell. Thermophotovoltaic (TPV) cells from the InGaAsP-family of III-V materials grown epitaxially on InP substrates would also benefit from such an InP/Si substrate. Additionally, a proposed four-junction solar cell fabricated by joining subcells of InGaAs and InGaAsP grown on InP with subcells of GaAs and AlInGaP grown on GaAs through a wafer-bonded interconnect would enable the independent selection of the subcell band gaps from well developed materials grown on lattice matched substrates. Substitution of

  13. High resistivity in InP by helium bombardment

    International Nuclear Information System (INIS)

    Focht, M.W.; Macrander, A.T.; Schwartz, B.; Feldman, L.C.

    1984-01-01

    Helium implants over a fluence range from 10 11 to 10 16 ions/cm 2 , reproducibly form high resistivity regions in both p- and n-type InP. Average resistivities of greater than 10 9 Ω cm for p-type InP and of 10 3 Ω cm for n-type InP are reported. Results are presented of a Monte Carlo simulation of helium bombardment into the compound target InP that yields the mean projected range and the range straggling

  14. [Effects of reduced solar radiation on winter wheat flag leaf net photosynthetic rate].

    Science.gov (United States)

    Zheng, You-Fei; Ni, Yan-Li; Mai, Bo-Ru; Wu, Rong-Jun; Feng, Yan; Sun, Jian; Li, Jian; Xu, Jing-Xin

    2011-06-01

    Taking winter wheat Triticum aestivum L. (cv. Yangmai 13) as test material, a field experiment was conducted in Nanjing City to study the effects of simulated reduced solar radiation on the diurnal variation of winter wheat flag leaf photosynthetic rate and the main affecting factors. Five treatments were installed, i. e., 15% (T15), 20% (T20) , 40% (T40), 60% (T60), and 100% (CK) of total incident solar radiation. Reduced solar irradiance increased the chlorophyll and lutein contents significantly, but decreased the net photosynthetic rate (Pn). Under different solar irradiance, the diurnal variation of Pn had greater difference, and the daily maximum Pn was in the order of CK > T60 > T40 > T 20 > T15. In CK, the Pn exhibited a double peak diurnal curve; while in the other four treatments, the Pn showed a single peak curve, and the peak was lagged behind that of CK. Correlation analysis showed that reduced solar irradiance was the main factor affecting the diurnal variation of Pn, but the physiological parameters also played important roles in determining the diurnal variation of Pn. In treatments T60 and T40, the photosynthesis active radiation (PAR), leaf temperature (T1) , stomatal conductance (Gs) , and transpiration rate (Tr) were significantly positively correlated with Pn, suggesting their positive effects on Pn. The intercellular CO2 concentration (Ci) and stomatal limitation (Ls) had significant negative correlations with Pn in treatments T60 and T40 but significant positive correlations with Pn in treatments T20 and T15, implying that the Ci and Ls had negative (or positive) effects on Pn when the solar irradiance was higher (or lower) than 40% of incident solar irradiance.

  15. The electronic structure of radial p-n junction silicon nanowires

    Science.gov (United States)

    Chiou, Shan-Haw; Grossman, Jeffrey

    2007-03-01

    Silicon nanowires with radial p-n junctions have recently been suggested for photovoltaic applications because incident light can be absorbed along the entire length of the wire, while photogenerated carriers only need to diffuse a maximum of one radius to reach the p-n junction. If the differential of the potential is larger than the binding energy of the electron-hole pair and has a range larger than the Bohr radius of electron-hole pair, then the charge separation mechanism will be similar to traditional silicon solar cells. However, in the small-diameter limit, where quantum confinement effects are prominent, both the exciton binding energy and the potential drop will increase, and the p-n junction itself may have a dramatically different character. We present ab initio calculations based on the generalized gradient approximation (GGA) of silicon nanowires with 2-3 nm diameter in the [111] growth direction. A radial p-n junction was formed by symmetrically doping boron and phosphorous at the same vertical level along the axis of the nanowire. The competition between the slope and character of the radial electronic potential and the exciton binding energy will presented in the context of a charge separation mechanism.

  16. Effect of Plasma, RF, and RIE Treatments on Properties of Double-Sided High Voltage Solar Cells with Vertically Aligned p-n Junctions

    Directory of Open Access Journals (Sweden)

    Mykola O. Semenenko

    2016-01-01

    Full Text Available Si-based solar cells with vertically aligned p-n junctions operating at high voltage were designed and fabricated. The plasma treatments and antireflection coating deposition on the working surfaces of both single- and multijunction cells were made using the special holders. It was shown that additional treatment of solar cells in argon plasma prior to hydrogen plasma treatment and deposition of diamond-like carbon antireflection films led to the improvement of the cell efficiency by up to 60%. Radio frequency waves support plasma generation and improve photoelectric conversion mainly due to reduction of internal stresses at the interfaces. Application of reactive ion etching technique removes the broken layer, reduces elastic strain in the wafer, decreases recombination of charge carriers in the bulk, and provides cell efficiency increase by up to ten times.

  17. On the Adjacent Strong Equitable Edge Coloring of PnPn, Pn ∨ Cn and Cn ∨ Cn

    OpenAIRE

    Liu Jun; Zhao Chuan Cheng; Yao Shu Xia; Guo Ren Zhi; Yue Qiu Ju

    2016-01-01

    A proper edge coloring of graph G is called equitable adjacent strong edge coloring if colored sets from every two adjacent vertices incident edge are different,and the number of edges in any two color classes differ by at most one,which the required minimum number of colors is called the adjacent strong equitable edge chromatic number. In this paper, we discuss the adjacent strong equitable edge coloring of join-graphs about PnPn, Pn ∨ Cn and Cn ∨ Cn.

  18. Indium phosphide (InP) for optical interconnects

    NARCIS (Netherlands)

    Lebby, M.; Ristic, S.; Calabretta, N.; Stabile, R.; Tekin, T.; Pitwon, R.; Håkansson, A.; Pleros, N.

    2016-01-01

    We present InP as the incumbent technology for data center transceiver and switching optics. We review the most popular InP monolithic integration approaches in light of photonic integration being recognized as an increasingly important technology for data center optics. We present Multi-Guide

  19. Thermal diffusion in nanostructured porous InP

    Indian Academy of Sciences (India)

    Nanostructured porous InP samples were prepared by electrochemical anodic dissolution of InP for various current densities and etching periods. The samples were characterized by SEM and photoluminescence (PL) where a blue shift was observed in PL. Thermal properties studied by photoacoustic (PA) spectroscopy ...

  20. Analysis of the photo voltage decay /PVD/ method for measuring minority carrier lifetimes in P-N junction solar cells

    Science.gov (United States)

    Von Roos, O.

    1981-01-01

    The photo voltage decay (PVD) method for the measurement of minority carrier lifetimes in P-N junction solar cells with cell thickness comparable to or even less than the minority carrier diffusion length is examined. The method involves the generation of free carriers in the quasi-neutral bulk material by flashes of light and the monitoring of the subsequent decay of the induced open-circuit voltages as the carriers recombine, which is dependent on minority carrier recombination lifetime. It is shown that the voltage versus time curve for an ordinary solar cell (N(+)-P junction) is proportional to the inverse minority carrier lifetime plus a factor expressing the ratio of diffusion length to cell thickness. In the case of an ideal back-surface-field cell (N(+)-P-P(+) junction) however, the slope is directly proportional to the inverse minority carrier lifetime. It is noted that since most BSF cells are not ideal, possessing a sizable back surface recombination velocity, the PVD measurements must be treated with caution and supplemented with other nonstationary methods.

  1. InP nanopore arrays for photoelectrochemical hydrogen generation.

    Science.gov (United States)

    Li, Qiang; Zheng, Maojun; Zhang, Bin; Zhu, Changqing; Wang, Faze; Song, Jingnan; Zhong, Miao; Ma, Li; Shen, Wenzhong

    2016-02-19

    We report a facile and large-scale fabrication of highly ordered one-dimensional (1D) indium phosphide (InP) nanopore arrays (NPs) and their application as photoelectrodes for photoelectrochemical (PEC) hydrogen production. These InP NPs exhibit superior PEC performance due to their excellent light-trapping characteristics, high-quality 1D conducting channels and large surface areas. The photocurrent density of optimized InP NPs is 8.9 times higher than that of planar counterpart at an applied potential of +0.3 V versus RHE under AM 1.5G illumination (100 mW cm(-2)). In addition, the onset potential of InP NPs exhibits 105 mV of cathodic shift relative to planar control. The superior performance of the nanoporous samples is further explained by Mott-Schottky and electrochemical impedance spectroscopy ananlysis.

  2. Solar cells based on InP/GaP/Si structure

    Science.gov (United States)

    Kvitsiani, O.; Laperashvil, D.; Laperashvili, T.; Mikelashvili, V.

    2016-10-01

    Solar cells (SCs) based on III-V semiconductors are reviewed. Presented work emphases on the Solar Cells containing Quantum Dots (QDs) for next-generation photovoltaics. In this work the method of fabrication of InP QDs on III-V semiconductors is investigated. The original method of electrochemical deposition of metals: indium (In), gallium (Ga) and of alloys (InGa) on the surface of gallium phosphide (GaP), and mechanism of formation of InP QDs on GaP surface is presented. The possibilities of application of InP/GaP/Si structure as SC are discussed, and the challenges arising is also considered.

  3. Effects of the electron beam on InP(100)

    International Nuclear Information System (INIS)

    Bouslama, M.; Jardin, C.; Ghamnia, M.

    1996-01-01

    Auger Electron Spectroscopy (AES) is performed to monitor the InP(100) surface evolution while it is irradiated by an electron beam of 5 KeV energy and 10 -3 A.cm -2 current density. A charge phenomenon appears during the irradiation of sputter-cleaned InP(100) by Ar + at low energy (500 eV). The deposition of phosphorus or antimony at room temperature on cleaned InP(100) is a good way of preventing this charging problem. This is also achieved by the growth of stoichiometric indium phosphide on InP(100) substrate, from an injection of phosphine and indium trimethyl whose ratio V/III is of 50, in a MOCVD (Metal Organic Chemical Vapor Deposition) reactor. The electron beam even acts to stimulate oxidation of the stoichiometric InP(100) surface involving on the top layers, into a well defined oxide such as InPO 4 or a contamination layer composed of carbon and oxygen. The partial pressure in the spectrometer is about 10 -9 Torr. The incident electrons produce breaking of (In-P) chemical bonds so that the resulting indium takes part in the oxidation process. The phosphorus is thought to be desorbed from the surface. (author)

  4. Growth of semi-insulating InP through nuclear doping

    International Nuclear Information System (INIS)

    Aliyev, M.I; Rashidova, Sh.Sh; Huseynli, M.A.

    2012-01-01

    Full text : Semi-insulating semiconductors are widely used in so-called dielectronics. Dielectric devices have quick response, good frequency characteristics, a low noise level, low sensitivity to temperature changes, etc. One of the most promising semiconductor materials is InP. At present annealing and doping are commonly used techniques to grow semi-insulating InP. The aim of this work was to grow semi-insulating InP through nuclear doping (by irradiation with gamma-quanta). InP single crystals were obtained by Czochralski method. Specimens were irradiated with doses of 10kGr at room temperature. Electrical conductivity and Hall effect were measured before and after irradiation in the temperature range 77 to 320K. After irradiation reduction in electrical conductivity was observed. This fact can be associated with formation of M-centers in positively threefold charged states of vacancy and antisite defects. Under irradiation first Ini interstitial atoms and phosphorus vacancies form. Further, the Ini atoms occupy the phosphorus vacancies. As a result there appear InP antiste defects, which along with indium vacancies form V I nI n p + In p + + complexes of the acceptor type. These complexes turn out to be traps for charge carriers and electrical conductivity of irradiated InP are sharply reduced to semi-insulating specimens

  5. Design issues for optimum solar cell configuration

    Science.gov (United States)

    Kumar, Atul; Thakur, Ajay D.

    2018-05-01

    A computer based simulation of solar cell structure is performed to study the optimization of pn junction configuration for photovoltaic action. The fundamental aspects of photovoltaic action viz, absorption, separation collection, and their dependence on material properties and deatails of device structures is discussed. Using SCAPS 1D we have simulated the ideal pn junction and shown the effect of band offset and carrier densities on solar cell performance. The optimum configuration can be achieved by optimizing transport of carriers in pn junction under effect of field dependent recombination (tunneling) and density dependent recombination (SRH, Auger) mechanisms.

  6. Interfacial reactions between thin films of zinc and (100) InP

    International Nuclear Information System (INIS)

    Kaminska, E.; Piotrowska, A.; Barcz, A.; Mizera, E.; Dynowska, E.

    1995-01-01

    The effects of interaction between thin films of Zn and (100)InP were studied with secondary ion mass spectrometry, X-ray diffraction and transmission electron microscopy. Zn was found to penetrate the native oxide on InP surface during deposition and to form an ohmic contact when deposited on highly doped n-type InP. Heat treatment causes the formation of Zn 3 P 2 phase lattice matched to InP. (author)

  7. Why does the disorder of R-pn and rac-pn ligands in the quasi-one-dimensional bromo-bridged NiIII complexes, [Ni(pn)2Br]Br2 (pn=1,2-diaminopropane) afford similar STM patterns?

    Science.gov (United States)

    Wu, Hashen; Kawakami, Daisuke; Sasaki, Mari; Xie, Jimin; Takaishi, Shinya; Kajiwara, Takashi; Miyasaka, Hitoshi; Yamashita, Masahiro; Matsuzaki, Hiroyuki; Okamoto, Hiroshi

    2007-09-03

    The disordered patterns of R- and rac-1,2-diaminopropane (pn) in quasi-one-dimensional bromo-bridged Ni(III) complexes, [NiIII(pn)2Br]Br2, have been investigated by single-crystal X-ray structure determination and scanning tunneling microscopy (STM). X-ray structure determination shows that the methyl moieties are disordered on the right- and left-hand sides with half occupancies in both compounds, while the carbon atoms of the ethylene moieties of pn ligands are disordered in [Ni(rac-pn)2Br]Br2 and not disordered in [Ni(R-pn)2Br]Br2. In the STM images of both compounds, the bright spots are not straight but fluctuated with the similar patterns. We have concluded that tunnel current from the STM tip to metal ions are detected via methyl groups of pn ligands.

  8. The X-ray mirror telescope and the pn-CCD detector of CAST

    CERN Document Server

    Kuster, M; Englhauser, J; Franz, J; Friedrich, P; Hartmann, R; Kang, D; Kotthaus, R; Lutz, Gerhard; Moralez, J; Serber, W; Strüder, L

    2004-01-01

    The Cern Axion Solar Telescope - CAST - uses a prototype 9 Tesla LHC superconducting dipole magnet to search for a hypothetical pseudoscalar particle, the axion, which was proposed by theory in the 1980s to solve the strong CP problem and which could be a dark matter candidate. In CAST a strong magnetic field is used to convert the solar axions to detectable photons via inverse Primakoff effect. The resulting X-rays are thermally distributed in the energy range of 1-7 keV and can be observed with conventional X-ray detectors. The most sensitive detector system of CAST is a pn-CCD detector originally developed for XMM-Newton combined with a Wolter I type X-ray mirror system. The combination of a focusing X-ray optics and a state of the art pn-CCD detector which combines high quantum efficiency, good spacial and energy resolution, and low background improves the sensitivity of the CAST experiment such that for the first time the axion photon coupling constant can be probed beyond the best astrophysical constrai...

  9. First principle analyses of direct bandgap solar cells with absorbing substrates versus mirrors

    Energy Technology Data Exchange (ETDEWEB)

    Kirk, Alexander P. [School of Electrical, Computer and Energy Engineering, Arizona State University, Tempe, Arizona 85287 (United States); Kirk, Wiley P. [Department of Materials Science and Engineering, University of Texas at Arlington, Arlington, Texas 76019 (United States)

    2013-11-07

    Direct bandgap InP, GaAs, CdTe, and Ga{sub 0.5}In{sub 0.5}P solar cells containing backside mirrors as well as parasitically absorbing substrates are analyzed for their limiting open circuit voltage and power conversion efficiency with comparison to record solar cells. From the principle of detailed balance, it is shown quantitatively that mirror solar cells have greater voltage and power conversion efficiency than their substrate counterparts. Next, the radiative recombination coefficient and maximum radiative lifetime of GaAs mirror and substrate solar cells are calculated and compared to the nonradiative Auger and Shockley-Read-Hall (SRH) lifetimes. Mirror solar cells have greater radiative lifetime than their substrate variants. Auger lifetime exceeds radiative lifetime for both substrate and mirror cells while SRH lifetime may be less or greater than radiative lifetime depending on trap concentration and capture cross section. Finally, the change in free energy of the photogenerated carriers is analyzed in a comparison between InP, GaAs, CdTe, and Ga{sub 0.5}In{sub 0.5}P mirror and substrate solar cells in order to characterize the relationship between solar photon quality and free energy management in solar cells with differing bandgaps. Wider bandgap visible threshold Ga{sub 0.5}In{sub 0.5}P solar cells make better use of the available change in free energy of the photogenerated charge carriers, even when normalized to the bandgap energy, than narrower bandgap near-IR threshold InP, GaAs, and CdTe solar cells.

  10. Study by AES, EELS Spectroscopy of electron Irradiation on InP and InPO4/InP in comparison with Monte Carlo simulation

    International Nuclear Information System (INIS)

    Lounis, Z; Bouslama, M; Hamaida, K; Abdellaoui, A; Ouerdane, A; Ghaffour, M; Berrouachedi, N; Jardin, C

    2012-01-01

    We give the great interest to characterise the InP and InPO 4 /InP submitted to electron beam irradiation owing to the Auger Electron Spectroscopy (AES) associated to both methods Electron Energy Loss Spectroscopy (EELS). The incident electron produces breaking of (In-P) chemical bonds. The electron beam even acts to stimulate oxidation of InP surface involving on the top layers. Other, the oxide InPO 4 developed on InP does appear very sensitive to the irradiation due to electron beam shown by the monitoring of EELS spectra recorded versus the irradiated times of the surface. There appears a new oxide thought to be In 2 O 3 . We give the simulation methods Casino (Carlo simulation of electron trajectory in solids) for determination with accuracy the loss energy of backscattered electrons and compared with reports results have been obtained with EELS Spectroscopy. These techniques of spectroscopy alone do not be able to verify the affected depth during interaction process. So, using this simulation method, we determine the interaction of electrons in the matter.

  11. Engineering MoSx/Ti/InP Hybrid Photocathode for Improved Solar Hydrogen Production.

    Science.gov (United States)

    Li, Qiang; Zheng, Maojun; Zhong, Miao; Ma, Liguo; Wang, Faze; Ma, Li; Shen, Wenzhong

    2016-07-19

    Due to its direct band gap of ~1.35 eV, appropriate energy band-edge positions, and low surface-recombination velocity, p-type InP has attracted considerable attention as a promising photocathode material for solar hydrogen generation. However, challenges remain with p-type InP for achieving high and stable photoelectrochemical (PEC) performances. Here, we demonstrate that surface modifications of InP photocathodes with Ti thin layers and amorphous MoSx nanoparticles can remarkably improve their PEC performances. A high photocurrent density with an improved PEC onset potential is obtained. Electrochemical impedance analyses reveal that the largely improved PEC performance of MoSx/Ti/InP is attributed to the reduced charge-transfer resistance and the increased band bending at the MoSx/Ti/InP/electrolyte interface. In addition, the MoSx/Ti/InP photocathodes function stably for PEC water reduction under continuous light illumination over 2 h. Our study demonstrates an effective approach to develop high-PEC-performance InP photocathodes towards stable solar hydrogen production.

  12. Young's Modulus of Wurtzite and Zinc Blende InP Nanowires.

    Science.gov (United States)

    Dunaevskiy, Mikhail; Geydt, Pavel; Lähderanta, Erkki; Alekseev, Prokhor; Haggrén, Tuomas; Kakko, Joona-Pekko; Jiang, Hua; Lipsanen, Harri

    2017-06-14

    The Young's modulus of thin conical InP nanowires with either wurtzite or mixed "zinc blende/wurtzite" structures was measured. It has been shown that the value of Young's modulus obtained for wurtzite InP nanowires (E [0001] = 130 ± 30 GPa) was similar to the theoretically predicted value for the wurtzite InP material (E [0001] = 120 ± 10 GPa). The Young's modulus of mixed "zinc blende/wurtzite" InP nanowires (E [111] = 65 ± 10 GPa) appeared to be 40% less than the theoretically predicted value for the zinc blende InP material (E [111] = 110 GPa). An advanced method for measuring the Young's modulus of thin and flexible nanostructures is proposed. It consists of measuring the flexibility (the inverse of stiffness) profiles 1/k(x) by the scanning probe microscopy with precise control of loading force in nanonewton range followed by simulations.

  13. An ellipsometric measurement of optical properties for InP surfaces

    International Nuclear Information System (INIS)

    Liu, X.; Irene, E.A.; Hattangady, S.; Fountain, G.

    1990-01-01

    Several chemical cleaning procedures for InP surfaces have been studied using ellipsometry. The strong influence of cleaning on the optical properties of InP surfaces suggests that the measurements involved the formation of surface films. In order to determine the complex index of refraction for InP, a novel method which employs ellipsometry measurements of a thin nonabsorbing film on a substrate rather than measurements of a bare surface has been explored. From the knowledge of the refractive index for a series of thicknesses of films on a substrate, the complex refractive index value for the substrate can be determined. Plasma enhanced chemical vapor deposition (PECVD) SiO 2 and Si 3 N 4 films on InP have been used for this experiment, and the complex refractive index for InP has been determined to be 3.521 + i0.300 at the wavelength of 632.8 nm

  14. Effective Surface Passivation of InP Nanowires by Atomic-Layer-Deposited Al2O3 with POx Interlayer.

    Science.gov (United States)

    Black, L E; Cavalli, A; Verheijen, M A; Haverkort, J E M; Bakkers, E P A M; Kessels, W M M

    2017-10-11

    III/V semiconductor nanostructures have significant potential in device applications, but effective surface passivation is critical due to their large surface-to-volume ratio. For InP such passivation has proven particularly difficult, with substantial depassivation generally observed following dielectric deposition on InP surfaces. We present a novel approach based on passivation with a phosphorus-rich interfacial oxide deposited using a low-temperature process, which is critical to avoid P-desorption. For this purpose we have chosen a PO x layer deposited in a plasma-assisted atomic layer deposition (ALD) system at room temperature. Since PO x is known to be hygroscopic and therefore unstable in atmosphere, we encapsulate this layer with a thin ALD Al 2 O 3 capping layer to form a PO x /Al 2 O 3 stack. This passivation scheme is capable of improving the photoluminescence (PL) efficiency of our state-of-the-art wurtzite (WZ) InP nanowires by a factor of ∼20 at low excitation. If we apply the rate equation analysis advocated by some authors, we derive a PL internal quantum efficiency (IQE) of 75% for our passivated wires at high excitation. Our results indicate that it is more reliable to calculate the IQE as the ratio of the integrated PL intensity at room temperature to that at 10 K. By this means we derive an IQE of 27% for the passivated wires at high excitation (>10 kW cm -2 ), which constitutes an unprecedented level of performance for undoped InP nanowires. This conclusion is supported by time-resolved PL decay lifetimes, which are also shown to be significantly higher than previously reported for similar wires. The passivation scheme displays excellent long-term stability (>7 months) and is additionally shown to substantially improve the thermal stability of InP surfaces (>300 °C), significantly expanding the temperature window for device processing. Such effective surface passivation is a key enabling technology for InP nanowire devices such as

  15. Effects of impurities on radiation damage in InP

    International Nuclear Information System (INIS)

    Yamaguchi, M.; Ando, K.

    1986-01-01

    Strong impurity effects upon introduction and annealing behavior of radiation-induced defects in InP irradiated with 1-MeV electrons have been found. The main defect center of 0.37-eV hole trap H4 in p-InP, which must be due to a point defect, is annealed even at room temperature. Its annealing rate is found to be proportional to the 2/3 power of the preirradiation carrier concentration in InP. Moreover, the density of the hole trap H5 (E/sub v/+0.52 eV) in p-InP, which must be due to a point defect--impurity complex, increases with increase in the InP carrier concentration. These results suggest that the radiation-induced defects in InP must recover through long-range diffusion mediated by impurity atoms. A model is proposed in which point defects diffuse to sinks through impurities so as to disappear or bind impurities so as to form point defect--impurity complexes. In addition to the long-range diffusion mechanism, the possibility of charge-state effects responsible for the thermal annealing of radiation-induced defects in InP is also discussed

  16. Wurtzite InP nanowire arrays grown by selective area MOCVD

    International Nuclear Information System (INIS)

    Chu, Hyung-Joon; Stewart, Lawrence; Yeh, Ting-Wei; Dapkus, P.D.

    2010-01-01

    InP nanowires are a unique material phase because this normally zincblende material forms in the wurtzite crystal structure below a critical diameter owing to the contribution of sidewalls to the total formation energy. This may allow control of the carrier transport and optical properties of InP nanowires for applications such as nano scale transistors, lasers and detectors. In this work, we describe the fabrication of InP nanowire arrays by selective area growth using MOCVD in the diameter range where the wurtzite structure is formed. The spatial growth rate in selective area growth is modeled by a diffusion model for the precursors. The proposed model achieves an average error of 9%. Electron microscopy shows that the grown InP nanowires are in the wurtzite crystal phase with many stacking faults. The threshold diameter of the crystal phase transition of InP nanowires is larger than the thermodynamic estimation. In order to explain this tendency, we propose a surface kinetics model based on a 2 x 2 reconstruction. This model can explain the increased tendency for wurtzite nanowire formation on InP (111)A substrates and the preferred growth direction of binary III-V compound semiconductor nanowires. (copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  17. Graphene enhanced field emission from InP nanocrystals.

    Science.gov (United States)

    Iemmo, L; Di Bartolomeo, A; Giubileo, F; Luongo, G; Passacantando, M; Niu, G; Hatami, F; Skibitzki, O; Schroeder, T

    2017-12-08

    We report the observation of field emission (FE) from InP nanocrystals (NCs) epitaxially grown on an array of p-Si nanotips. We prove that FE can be enhanced by covering the InP NCs with graphene. The measurements are performed inside a scanning electron microscope chamber with a nano-controlled W-thread used as an anode. We analyze the FE by Fowler-Nordheim theory and find that the field enhancement factor increases monotonically with the spacing between the anode and the cathode. We also show that InP/p-Si junction has a rectifying behavior, while graphene on InP creates an ohmic contact. Understanding the fundamentals of such nanojunctions is key for applications in nanoelectronics.

  18. GaInAs Junction FET with InP buffer layer prepared by selective ion implantation of Be and rapid thermal annealing

    International Nuclear Information System (INIS)

    Selders, J.; Wachs, H.J.; Jurgensen, H.

    1986-01-01

    GaInAs JFETs were fabricated on VPE-grown GaInAs layers. The pn junctions have been realised with Be ion implantation and rapid thermal annealing. The devices show a high transconductance of 130 mS/mm and an electron saturation velocity of 1.8 x 10 7 cm/s. Channel mobilities measured at the complete device are as high as 6800 cm 2 /Vs. These excellent device properties are due to the use of an undoped InP buffer layer which avoids the diffusion of Fe from the substrate into the active layer. The data were supported by S-parameter measurements which gave a frequency limit of 20 GHz for gate dimensions of 1.6 by 200 μm 2 . (author)

  19. Characterization of InP and InGaN quantum dots for single photon sources and AlGaInAs quantum dots in intermediate band solar cells

    International Nuclear Information System (INIS)

    Kremling, Stefan

    2014-01-01

    This thesis describes the characterization of semiconductor quantum dots (QDs) in different material systems with potential applications as single photon emitters or intermediate band solar cells. All investigations were carried out by means of optical spectroscopy methods. First, the theoretical background regarding the physics of QDs with respect to their electronic structure and their associated statistical properties are presented. Especially peculiarities of photon statistics of light are explained. Moreover, a closer look at the physics of solar cells and the respective carrier transport is given. Then experimental methods, which were used to characterize the QD-samples, are briefly explained. First, the components and techniques of optical spectroscopy for the study of individual, isolated QDs are described. Second, different experimental technologies for the characterization of solar cells are discussed. The method for measuring the two-photon-absorption process is explained in detail. The section of experimental results begins with studies of individual and spectrally isolated InP QD. Due to the low surface density of one QD per μm 2 , it is possible to study the physical properties of individual QDs optically without additional lateral sample structuring. Based on power and polarization dependent measurements, various luminescence peaks of a single QD were associated with different exciton states. In addition, the QDs were tested subject to an external magnetic field in a Faraday configuration. Finally, the temporal photon statistics of a single QD was tested using autocorrelation measurement. Afterwards, InP QDs manufactured by cyclic material deposition with growth interruptions were investigated by means of PL spectroscopy. Based on excitation power and time-resolved measurements on the QD ensemble, a bimodal QD distribution of type-I and type-II band alignment was observed. In addition, different exciton states were identified on spectrally isolated

  20. Long-Term INP Measurements within the BACCHUS project

    Science.gov (United States)

    Schrod, Jann; Bingemer, Heinz; Curtius, Joachim

    2016-04-01

    The European research project BACCHUS (Impact of Biogenic versus Anthropogenic emissions on Clouds and Climate: towards a Holistic UnderStanding) studies the interactions between aerosols, clouds and the climate system, and tries to reconstruct pre-industrial aerosol and cloud conditions from data collected in pristine environments. The number concentration of Ice Nucleating Particles (INP) is an important, yet scarcely known parameter. As a partner of Work package 1 of BACCHUS we began in September 2014 to operate a globally spanned network of four INP sampling stations, which is the first of its kind. The stations are located at the ATTO observatory in the Brazilian Rainforest, the Caribbean Sea (Martinique), the Zeppelin Observatory at Svalbard in the Arctic, and in central Europe (Germany). Samples are collected routinely every day or every few days by electrostatic precipitation of aerosol particles onto Si substrates. The samples are stored in petri-slides, and shipped to our laboratory in Frankfurt, Germany. The number of ice nucleating particles on the substrate is analyzed in the isothermal static diffusion chamber FRIDGE by growing ice on the INP and photographing and counting the crystals. The measurements in the temperature range from -20°C to -30°C and relative humidities of 100-135% (with respect to ice) address primarily the deposition/condensation nucleation modes. Here we present INP and supporting aerosol data from this novel INP network for the first time.

  1. Epitaxial growth of InP on SI by MOCVD

    International Nuclear Information System (INIS)

    Konushi, F.; Seki, A.; Kudo, J.; Sato, H.; Kakimoto, S.; Fukushima, T.; Kubota, Y.; Koba, M.

    1988-01-01

    The authors have studied the heteroepitaxial growth of InP on large diameter Si substrates using MOCVD. A new MOCVD system with four inch wafer size capability was utilized in the growth. Single domain InP films have been successfully grown on four inch Si substrates by using a new heterostructure with a thin GaAs intermediate layer. In this paper, the authors describe the crystalline quality and residual stress of InP epilayers, estimated by etch pit density and x-ray diffraction, respectively. The authors also reports on the reduction of EPD by post-growth annealing

  2. Susceptor and proximity rapid thermal annealing of InP

    International Nuclear Information System (INIS)

    Katz, A.; Pearton, S.J.; Geva, M.

    1990-01-01

    This paper presents a comparison between the efficiency of InP rapid thermal annealing within two types of SiC-coated graphite susceptors and by using the more conventional proximity approach, in providing degradation-free substrate surface morphology. The superiority of annealing within a susceptor was clearly demonstrated through the evaluation of AuGe contact performance to carbon-implanted InP substrates, which were annealed to activate the implants prior to the metallization. The susceptor annealing provided better protection against edge degradation, slip formation and better surface morphology, due to the elimination of P outdiffusion and pit formation. The two SiC-coated susceptors that were evaluated differ from each other in their geometry. The first type must be charged with the group V species prior to any annealing cycle. Under the optimum charging conditions, effective surface protection was provided only to one anneal (750 degrees C, 10s) of InP before charging was necessary. The second contained reservoirs for provision of the group V element partial pressure, enabled high temperature annealing at the InP without the need for continual recharging of the susceptor. Thus, one has the ability to subsequentially anneal a lot of InP wafers at high temperatures without inducing any surface deterioration

  3. Photocurrent generation in lateral graphene p-n junction created by electron-beam irradiation

    KAUST Repository

    Yu, Xuechao; Shen, Youde; Liu, Tao; Wu, Tao; Jie Wang, Qi

    2015-01-01

    Graphene has been considered as an attractive material for optoelectronic applications such as photodetectors owing to its extraordinary properties, e.g. broadband absorption and ultrahigh mobility. However, challenges still remain in fundamental and practical aspects of the conventional graphene photodetectors which normally rely on the photoconductive mode of operation which has the drawback of e.g. high dark current. Here, we demonstrated the photovoltaic mode operation in graphene p-n junctions fabricated by a simple but effective electron irradiation method that induces n-type doping in intrinsic p-type graphene. The physical mechanism of the junction formation is owing to the substrate gating effect caused by electron irradiation. Photoresponse was obtained for this type of photodetector because the photoexcited electron-hole pairs can be separated in the graphene p-n junction by the built-in potential. The fabricated graphene p-n junction photodetectors exhibit a high detectivity up to ~3 × 1010 Jones (cm Hz1/2 W−1) at room temperature, which is on a par with that of the traditional III–V photodetectors. The demonstrated novel and simple scheme for obtaining graphene p-n junctions can be used for other optoelectronic devices such as solar cells and be applied to other two dimensional materials based devices.

  4. Photocurrent generation in lateral graphene p-n junction created by electron-beam irradiation

    KAUST Repository

    Yu, Xuechao

    2015-07-08

    Graphene has been considered as an attractive material for optoelectronic applications such as photodetectors owing to its extraordinary properties, e.g. broadband absorption and ultrahigh mobility. However, challenges still remain in fundamental and practical aspects of the conventional graphene photodetectors which normally rely on the photoconductive mode of operation which has the drawback of e.g. high dark current. Here, we demonstrated the photovoltaic mode operation in graphene p-n junctions fabricated by a simple but effective electron irradiation method that induces n-type doping in intrinsic p-type graphene. The physical mechanism of the junction formation is owing to the substrate gating effect caused by electron irradiation. Photoresponse was obtained for this type of photodetector because the photoexcited electron-hole pairs can be separated in the graphene p-n junction by the built-in potential. The fabricated graphene p-n junction photodetectors exhibit a high detectivity up to ~3 × 1010 Jones (cm Hz1/2 W−1) at room temperature, which is on a par with that of the traditional III–V photodetectors. The demonstrated novel and simple scheme for obtaining graphene p-n junctions can be used for other optoelectronic devices such as solar cells and be applied to other two dimensional materials based devices.

  5. A study of 1/f noise in InP grown by CBE

    NARCIS (Netherlands)

    Chen, X.Y.; Leijs, M.R.

    1996-01-01

    The origin of low-frequency noise in InP was studied experimentally by measuring the noise of InP layers grown by chemical beam epitaxy (CBE). Such InP layers are unintentionally doped, but of varying purity and always of n-type conductivity. We performed noise measurements at temperatures from 77

  6. Single Atomically Sharp Lateral Monolayer p-n Heterojunction Solar Cells with Extraordinarily High Power Conversion Efficiency

    KAUST Repository

    Tsai, Meng-Lin

    2017-06-26

    The recent development of 2D monolayer lateral semiconductor has created new paradigm to develop p-n heterojunctions. Albeit, the growth methods of these heterostructures typically result in alloy structures at the interface, limiting the development for high-efficiency photovoltaic (PV) devices. Here, the PV properties of sequentially grown alloy-free 2D monolayer WSe-MoS lateral p-n heterojunction are explores. The PV devices show an extraordinary power conversion efficiency of 2.56% under AM 1.5G illumination. The large surface active area enables the full exposure of the depletion region, leading to excellent omnidirectional light harvesting characteristic with only 5% reduction of efficiency at incident angles up to 75°. Modeling studies demonstrate the PV devices comply with typical principles, increasing the feasibility for further development. Furthermore, the appropriate electrode-spacing design can lead to environment-independent PV properties. These robust PV properties deriving from the atomically sharp lateral p-n interface can help develop the next-generation photovoltaics.

  7. Damage formation and annealing in InP due to swift heavy ions

    International Nuclear Information System (INIS)

    Kamarou, A.; Wesch, W.; Wendler, E.; Klaumuenzer, S.

    2004-01-01

    Virgin and pre-damaged InP samples were irradiated at room temperature (RT) and at liquid nitrogen temperature (LNT) with different fluences of 140 MeV Kr, 390 MeV Xe and 600 MeV Au ions. The pre-damaging was performed with 600 keV Ge ions at LNT to obtain different damage levels. The samples were analysed by means of Rutherford backscattering spectrometry (RBS) in random and channelling geometry. A relatively weak damage accumulation in virgin InP and a very significant defect annealing in pre-damaged InP occurs due to 140 MeV Kr irradiation. The damaging of virgin InP with 390 MeV Xe and 600 MeV Au is much more efficient in comparison with that of 140 MeV Kr. Further, annealing of the pre-damaged InP due to 390 MeV Xe irradiation is hardly visible. At LNT InP appears to be much more radiation-resistant to swift heavy ion (SHI) irradiation than at RT. Our results show that during SHI irradiation of InP both damage formation and damage annealing occur simultaneously. Whether the first or the second one plays a more important role depends on the SHI mass and energy

  8. Upper atmosphere research at INPE

    International Nuclear Information System (INIS)

    Clemesha, B.R.

    1984-01-01

    Upper atmosphere research at INPE is mainly concerned with the chemistry and dynamics of the stratosphere, upper mesosphere and lower thermosphere, and the middle thermosphere. Experimental work includes lidar observations of the stratospheric aerosol, measurements of stratospheric ozone by Dobson spectrophotometers and by balloon and rocket-borne sondes, lidar measurements of atmospheric sodium, and photometric observations of O, O 2 , OH and Na emissions, including interferrometric measurements of the OI6300 emission for the purpose of determing thermospheric winds and temperature. The airglow observations also include measurements of a number of emissions produced by the precipitation of energetic neutral particles generated by charge exchange in the ring current. Some recent results of INPE's upper atmosphere program are presented. (Author) [pt

  9. Surface photovoltage study of InP and Zn3P2

    International Nuclear Information System (INIS)

    Thurgate, S.M.; Lacuesta, T.D.; Huck, N.R.

    1989-01-01

    The surface photovoltage spectra of InP and Zn 3 P 2 were measured using a Kelvin probe to determine the contact potential difference between the sample and the probe as a function of the wavelength of illuminating light. The features in the resulting spectra were found to be sensitive to ion bombardment. The photovoltage spectra obtained from the InP differed from previously reported SPC spectra in that it showed clear evidence of surface states (or interfacial states) at 0.86 eV and 0.68 eV above VBM. It was found that the features in the spectrum of Zn 3 P 2 were reduced by ion bombardment, but not removed completely, whereas the features in the InP spectra were completely removed. Exposure of the ion bombarded urface to air restored the features of Zn 3 P 2 but only produced a small change in the spectrum of the InP. The loss of features in the InP spectra can be attributed to damage in the substrate caused by the ion bombardment even though the oxide layer was not removed before the damage occurred. Zn 3 P 2 was not as sensitive to ion damage as InP. (orig.)

  10. Modelling and design of high efficiency radiation tolerant indium phosphide space solar cells

    International Nuclear Information System (INIS)

    Goradia, C.; Geier, J.V.; Weinberg, I.

    1987-01-01

    Using a fairly comprehensive model, the authors did a parametric variation study of the InP shallow homojunction solar cell with a view to determining the maximum realistically achievable efficiency and an optimum design that would yield this efficiency. Their calculations show that with good quality epitaxial material, a BOL efficiency of about 20.3% at 1AMO, 25 0 C may be possible. The design parameters of the near-optimum cell are given. Also presented are the expected radiation damage of the performance parameters by 1MeV electrons and a possible explanation of the high radiation tolerance of InP solar cells

  11. Superconductivity and Competing Ordered Phase in RuPn (Pn = As, P)

    Science.gov (United States)

    Hirai, Daigorou; Takayama, Tomohiro; Hashizume, Daisuke; Yamamoto, Ayako; Takagi, Hidenori

    2011-03-01

    Unconventional superconductivity likely manifests itself when some competing electronic phases are suppressed down to zero temperature such as cuprates and iron-pnictide superconductors. Therefore, the correlated metallic state neighboring a competing electronic ordering can be a promising playground for unconventional superconductivity. Here we report superconductivity emerging adjacent to electronically ordered phases of RuPn (Pn = As, P). We found that RuAs(P) exhibits phase transitions at 240 (265) K, which is discerned as a drop of magnetic susceptibility or a resistivity upturn. Such anomalies can be suppressed by substituting Rh to the Ru site. Accompanied by the disappearance of the electronic order, superconductivity was found to emerge below 1.8 K and 3.8 K for RuAs and RuP, respectively. The superconductivity in Rh substituted RuPn, which neighbors a competing electronic order, might exhibit an exotic pairing state as seen in the unconventional superconductors known to date.

  12. Spectroscopic determination of valence band parameters in InP

    International Nuclear Information System (INIS)

    Lewis, R.A.; Lough, B.C.C.

    2003-01-01

    Full text: The general form of the Hamiltonian for an electron or hole in a semiconductor has been given by Luttinger. The valence band is characterised by three parameters - γ 1 , γ 2 , γ 3 -now commonly known as the Luttinger parameters. Despite many investigations there is still considerable uncertainty regarding the Luttinger parameters of InP. The situation has been reviewed by Hackenberg et al. These authors themselves sought to determine the Luttinger parameters by hot-electron luminescence and discovered that many Luttinger parameter triplets were consistent with their data. We employ a spectroscopic approach to estimating valence-band parameters in InP. Calculations have been made for both the unperturbed energy levels and the energy levels in a magnetic field of acceptor impurities in semiconductors characterised by different Luttinger parameters. We compare our recent experimental data for the transitions associated with the Zn acceptor impurity in InP in magnetic fields up to 30 T to determine the most appropriate set of valence-band parameters for InP

  13. Carrier thermalization dynamics in single zincblende and wurtzite InP Nanowires.

    Science.gov (United States)

    Wang, Yuda; Jackson, Howard E; Smith, Leigh M; Burgess, Tim; Paiman, Suriati; Gao, Qiang; Tan, Hark Hoe; Jagadish, Chennupati

    2014-12-10

    Using transient Rayleigh scattering (TRS) measurements, we obtain photoexcited carrier thermalization dynamics for both zincblende (ZB) and wurtzite (WZ) InP single nanowires (NW) with picosecond resolution. A phenomenological fitting model based on direct band-to-band transition theory is developed to extract the electron-hole-plasma density and temperature as a function of time from TRS measurements of single nanowires, which have complex valence band structures. We find that the thermalization dynamics of hot carriers depends strongly on material (GaAs NW vs InP NW) and less strongly on crystal structure (ZB vs WZ). The thermalization dynamics of ZB and WZ InP NWs are similar. But a comparison of the thermalization dynamics in ZB and WZ InP NWs with ZB GaAs NWs reveals more than an order of magnitude slower relaxation for the InP NWs. We interpret these results as reflecting their distinctive phonon band structures that lead to different hot phonon effects. Knowledge of hot carrier thermalization dynamics is an essential component for effective incorporation of nanowire materials into electronic devices.

  14. Design and Photovoltaic Properties of Graphene/Silicon Solar Cell

    Science.gov (United States)

    Xu, Dikai; Yu, Xuegong; Yang, Lifei; Yang, Deren

    2018-04-01

    Graphene/silicon (Gr/Si) Schottky junction solar cells have attracted widespread attention for the fabrication of high-efficiency and low-cost solar cells. However, their performance is still limited by the working principles of Schottky junctions. Modulating the working mechanism of the solar cells into a quasi p-n junction has advantages, including higher open-circuit voltage (V OC) and less carrier recombination. In this study, Gr/Si quasi p-n junction solar cells were formed by inserting a tunneling Al2O3 interlayer in-between graphene and silicon, which led to obtain the PCE up to 8.48% without antireflection or chemical doping techniques. Our findings could pave a new way for the development of Gr/Si solar cells.

  15. High efficiency double sided solar cells

    International Nuclear Information System (INIS)

    Seddik, M.M.

    1990-06-01

    Silicon technology state of the art for single crystalline was given to be limited to less than 20% efficiency. A proposed new form of photovoltaic solar cell of high current high efficiency with double sided structures has been given. The new forms could be n ++ pn ++ or p ++ np ++ double side junctions. The idea of double sided devices could be understood as two solar cells connected back-to-back in parallel electrical connection, in which the current is doubled if the cell is illuminated from both sides by a V-shaped reflector. The cell is mounted to the reflector such that each face is inclined at an angle of 45 deg. C to each side of the reflector. The advantages of the new structure are: a) High power devices. b) Easy to fabricate. c) The cells are used vertically instead of horizontal use of regular solar cell which require large area to install. This is very important in power stations and especially for satellite installation. If the proposal is made real and proved to be experimentally feasible, it would be a new era for photovoltaic solar cells since the proposal has already been extended to even higher currents. The suggested structures could be stated as: n ++ pn ++ Vp ++ np ++ ;n ++ pn ++ Vn ++ pn ++ ORp ++ np ++ Vp ++ np ++ . These types of structures are formed in wedged shape to employ indirect illumination by either parabolic; conic or V-shaped reflectors. The advantages of these new forms are low cost; high power; less in size and space; self concentrating; ... etc. These proposals if it happens to find their ways to be achieved experimentally, I think they will offer a short path to commercial market and would have an incredible impact on solar cell technology and applications. (author). 12 refs, 5 figs

  16. TP53inp1 Gene Is Implicated in Early Radiation Response in Human Fibroblast Cells

    Directory of Open Access Journals (Sweden)

    Nikolett Sándor

    2015-10-01

    Full Text Available Tumor protein 53-induced nuclear protein-1 (TP53inp1 is expressed by activation via p53 and p73. The purpose of our study was to investigate the role of TP53inp1 in response of fibroblasts to ionizing radiation. γ-Ray radiation dose-dependently induces the expression of TP53inp1 in human immortalized fibroblast (F11hT cells. Stable silencing of TP53inp1 was done via lentiviral transfection of shRNA in F11hT cells. After irradiation the clonogenic survival of TP53inp1 knockdown (F11hT-shTP cells was compared to cells transfected with non-targeting (NT shRNA. Radiation-induced senescence was measured by SA-β-Gal staining and autophagy was detected by Acridine Orange dye and microtubule-associated protein-1 light chain 3 (LC3B immunostaining. The expression of TP53inp1, GDF-15, and CDKN1A and alterations in radiation induced mitochondrial DNA deletions were evaluated by qPCR. TP53inp1 was required for radiation (IR induced maximal elevation of CDKN1A and GDF-15 expressions. Mitochondrial DNA deletions were increased and autophagy was deregulated following irradiation in the absence of TP53inp1. Finally, we showed that silencing of TP53inp1 enhances the radiation sensitivity of fibroblast cells. These data suggest functional roles for TP53inp1 in radiation-induced autophagy and survival. Taken together, we suppose that silencing of TP53inp1 leads radiation induced autophagy impairment and induces accumulation of damaged mitochondria in primary human fibroblasts.

  17. Ultralow surface recombination velocity in InP nanowires probed by terahertz spectroscopy.

    Science.gov (United States)

    Joyce, Hannah J; Wong-Leung, Jennifer; Yong, Chaw-Keong; Docherty, Callum J; Paiman, Suriati; Gao, Qiang; Tan, H Hoe; Jagadish, Chennupati; Lloyd-Hughes, James; Herz, Laura M; Johnston, Michael B

    2012-10-10

    Using transient terahertz photoconductivity measurements, we have made noncontact, room temperature measurements of the ultrafast charge carrier dynamics in InP nanowires. InP nanowires exhibited a very long photoconductivity lifetime of over 1 ns, and carrier lifetimes were remarkably insensitive to surface states despite the large nanowire surface area-to-volume ratio. An exceptionally low surface recombination velocity (170 cm/s) was recorded at room temperature. These results suggest that InP nanowires are prime candidates for optoelectronic devices, particularly photovoltaic devices, without the need for surface passivation. We found that the carrier mobility is not limited by nanowire diameter but is strongly limited by the presence of planar crystallographic defects such as stacking faults in these predominantly wurtzite nanowires. These findings show the great potential of very narrow InP nanowires for electronic devices but indicate that improvements in the crystallographic uniformity of InP nanowires will be critical for future nanowire device engineering.

  18. Heterostructures (CaSrBa)F2 on InP for Optoelectronics

    National Research Council Canada - National Science Library

    Pyshkin, Sergei

    1995-01-01

    Temperature-reduced MBE growth of group II-a fluorides onto InP( 100) surface as well as optimal cleaning and passivation procedures for InP wafers have been newly developed taking into account exsisting literature data...

  19. All-optical signal processing using InP photonic-crystal nanocavity switches

    DEFF Research Database (Denmark)

    Yu, Yi; Vukovic, Dragana; Heuck, Mikkel

    2014-01-01

    In this paper, we present recent progress in experimental characterization of InP photonic-crystal nanocavity switches. Pump-probe measurements on an InP PhC H0 cavity show large-contrast ultrafast switching at low pulse energy. At large pulse energies, a large resonance shift passing across...... for the joint effects of fast carrier diffusion, slow surface and bulk recombination. Utilizin g the simple InP PhC nanocavity structure, we successfully dem onstrate 10-Gb/s RZ- OOK all-optical modulation with low energy consumption....

  20. Unit cell parameters of wurtzite InP nanowires determined by x-ray diffraction.

    Science.gov (United States)

    Kriegner, D; Wintersberger, E; Kawaguchi, K; Wallentin, J; Borgström, M T; Stangl, J

    2011-10-21

    High resolution x-ray diffraction is used to study the structural properties of the wurtzite polytype of InP nanowires. Wurtzite InP nanowires are grown by metal-organic vapor phase epitaxy using S-doping. From the evaluation of the Bragg peak position we determine the lattice parameters of the wurtzite InP nanowires. The unit cell dimensions are found to differ from the ones expected from geometric conversion of the cubic bulk InP lattice constant. The atomic distances along the c direction are increased whereas the atomic spacing in the a direction is reduced in comparison to the corresponding distances in the zinc-blende phase. Using core/shell nanowires with a thin core and thick nominally intrinsic shells we are able to determine the lattice parameters of wurtzite InP with a negligible influence of the S-doping due to the much larger volume in the shell. The determined material properties will enable the ab initio calculation of electronic and optical properties of wurtzite InP nanowires.

  1. Novel pneumoviruses (PnVs): Evolution and inflammatory pathology

    International Nuclear Information System (INIS)

    Glineur, Stephanie F.; Renshaw, Randall W.; Percopo, Caroline M.; Dyer, Kimberly D.; Dubovi, Edward J.; Domachowske, Joseph B.; Rosenberg, Helene F.

    2013-01-01

    A previous report of a novel pneumovirus (PnV) isolated from the respiratory tract of a dog described its significant homology to the rodent pathogen, pneumonia virus of mice (PVM). The original PnV–Ane4 pathogen replicated in and could be re-isolated in infectious state from mouse lung but elicited minimal mortality compared to PVM strain J3666. Here we assess phylogeny and physiologic responses to 10 new PnV isolates. The G/glycoprotein sequences of all PnVs include elongated amino-termini when compared to the characterized PVMs, and suggest division into groups A and B. While we observed significant differences in cytokine production and neutrophil recruitment to the lungs of BALB/c mice in response to survival doses (50 TCID 50 units) of representative group A (114378-10-29-KY-F) and group B (7968-11-OK) PnVs, we observed no evidence for positive selection (dN>dS) among the PnV/PnV, PVM/PnV or PVM/PVM G/glycoprotein or F/fusion protein sequence pairs. - Highlights: • We consider ten novel isolates of the pneumovirus (PnV) first described by Renshaw and colleagues. • The G/glycoprotein sequences of all PnVs include elongated amino-termini when compared to PVM. • We detect cytokine production and neutrophil recruitment to the lungs of mice in response to PnV. • We observed no evidence for positive selection (dN>dS) among the gene sequence pairs

  2. Novel pneumoviruses (PnVs): Evolution and inflammatory pathology

    Energy Technology Data Exchange (ETDEWEB)

    Glineur, Stephanie F. [Inflammation Immunobiology Section, Laboratory of Allergic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892-1883 (United States); Renshaw, Randall W. [Animal Health Diagnostic Center, College of Veterinary Medicine, Cornell University, PO Box 5786, Ithaca, New York, NY 14851-5786 (United States); Percopo, Caroline M.; Dyer, Kimberly D. [Inflammation Immunobiology Section, Laboratory of Allergic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892-1883 (United States); Dubovi, Edward J. [Animal Health Diagnostic Center, College of Veterinary Medicine, Cornell University, PO Box 5786, Ithaca, New York, NY 14851-5786 (United States); Domachowske, Joseph B. [Department of Pediatrics, SUNY Upstate Medical University, Syracuse, NY 13210 (United States); Rosenberg, Helene F., E-mail: hrosenberg@niaid.nih.gov [Inflammation Immunobiology Section, Laboratory of Allergic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892-1883 (United States)

    2013-09-01

    A previous report of a novel pneumovirus (PnV) isolated from the respiratory tract of a dog described its significant homology to the rodent pathogen, pneumonia virus of mice (PVM). The original PnV–Ane4 pathogen replicated in and could be re-isolated in infectious state from mouse lung but elicited minimal mortality compared to PVM strain J3666. Here we assess phylogeny and physiologic responses to 10 new PnV isolates. The G/glycoprotein sequences of all PnVs include elongated amino-termini when compared to the characterized PVMs, and suggest division into groups A and B. While we observed significant differences in cytokine production and neutrophil recruitment to the lungs of BALB/c mice in response to survival doses (50 TCID{sub 50} units) of representative group A (114378-10-29-KY-F) and group B (7968-11-OK) PnVs, we observed no evidence for positive selection (dN>dS) among the PnV/PnV, PVM/PnV or PVM/PVM G/glycoprotein or F/fusion protein sequence pairs. - Highlights: • We consider ten novel isolates of the pneumovirus (PnV) first described by Renshaw and colleagues. • The G/glycoprotein sequences of all PnVs include elongated amino-termini when compared to PVM. • We detect cytokine production and neutrophil recruitment to the lungs of mice in response to PnV. • We observed no evidence for positive selection (dN>dS) among the gene sequence pairs.

  3. Different growth regimes in InP nanowire growth mediated by Ag nanoparticles.

    Science.gov (United States)

    Oliveira, D S; Zavarize, M; Tizei, L H G; Walls, M; Ospina, C A; Iikawa, F; Ugarte, D; Cotta, M A

    2017-12-15

    We report on the existence of two different regimes in one-step Ag-seeded InP nanowire growth. The vapor-liquid-solid-mechanism is present at larger In precursor flows and temperatures, ∼500 °C, yielding high aspect ratio and pure wurtzite InP nanowires with a semi-spherical metal particle at the thin apex. Periodic diameter oscillations can be achieved under extreme In supersaturations at this temperature range, showing the presence of a liquid catalyst. However, under lower temperatures and In precursor flows, large diameter InP nanowires with mixed wurtzite/zincblende segments are obtained, similarly to In-assisted growth. Chemical composition analysis suggest that In-rich droplet formation is catalyzed at the substrate surface via Ag nanoparticles; this process might be facilitated by the sulfur contamination detected in these nanoparticles. Furthermore, part of the original Ag nanoparticle remains solid and is embedded inside the actual catalyst, providing an in situ method to switch growth mechanisms upon changing In precursor flow. Nevertheless, our Ag-seeded InP nanowires exhibit overall optical emission spectra consistent with the observed structural properties and similar to Au-catalyzed InP nanowires. We thus show that Ag nanoparticles may be a suitable replacement for Au in InP nanowire growth.

  4. Photoacoustic investigation of doped InP using open cell configuration

    NARCIS (Netherlands)

    George, S.D.; Vallabhan, C.P.G.; Heck, M.J.R.; Radhakrishnan, P.; Nampoori, V.P.N.

    2002-01-01

    An open cell photoacoustic (PA) configuration was employed to evaluate the thermal diffusivity of intrinsic InP as well as InP doped with tin and iron. Thermal diffusivity data were evaluated from variation of phase of PA signal as a function of modulation frequency. In doped samples, we observe a

  5. Control of persistent photoconductivity in nanostructured InP through morphology design

    International Nuclear Information System (INIS)

    Monaico, Ed; Postolache, V; Borodin, E; Lupan, O; Tiginyanu, I M; Ursaki, V V; Adelung, R; Nielsch, K

    2015-01-01

    In this paper, we show that long-duration-photoconductivity decay (LDPCD) and persistent photoconductivity (PPC) in porous InP structures fabricated by anodic etching of bulk substrates can be controlled through the modification of the sample morphology. Particularly, the PPC inherent at low temperatures to porous InP layers with the thickness of skeleton walls comparable with pore diameters is quenched in structures consisting of ultrathin walls produced at high anodization voltages. The relaxation of photoconductivity in bulk InP substrates, porous layers, and utrathin membranes is investigated as a function of temperature and excitation power density. The obtained results suggest that PPC in porous InP layers is due to porosity induced potential barriers which hinder the recombination of photoexcited carriers, while the photoconductivity relaxation processes in ultrathin membranes are governed by surface states. (paper)

  6. Optical phonon modes of wurtzite InP

    Science.gov (United States)

    Gadret, E. G.; de Lima, M. M.; Madureira, J. R.; Chiaramonte, T.; Cotta, M. A.; Iikawa, F.; Cantarero, A.

    2013-03-01

    Optical vibration modes of InP nanowires in the wurtzite phase were investigated by Raman scattering spectroscopy. The wires were grown along the [0001] axis by the vapor-liquid-solid method. The A1(TO), E2h, and E1(TO) phonon modes of the wurtzite symmetry were identified by using light linearly polarized along different directions in backscattering configuration. Additionally, forbidden longitudinal optical modes have also been observed. Furthermore, by applying an extended 11-parameter rigid-ion model, the complete dispersion relations of InP in the wurtzite phase have been calculated, showing a good agreement with the Raman experimental data.

  7. Diffusion length variation in 0.5- and 3-MeV-proton-irradiated, heteroepitaxial indium phosphide solar cells

    Science.gov (United States)

    Jain, Raj K.; Weinberg, Irving; Flood, Dennis J.

    1993-01-01

    Indium phosphide (InP) solar cells are more radiation resistant than gallium arsenide (GaAs) and silicon (Si) solar cells, and their growth by heteroepitaxy offers additional advantages leading to the development of light weight, mechanically strong, and cost-effective cells. Changes in heteroepitaxial InP cell efficiency under 0.5- and 3-MeV proton irradiations have been explained by the variation in the minority-carrier diffusion length. The base diffusion length versus proton fluence was calculated by simulating the cell performance. The diffusion length damage coefficient, K(sub L), was also plotted as a function of proton fluence.

  8. Synthesis of colloidal InP nanocrystal quantum dots

    International Nuclear Information System (INIS)

    Sirbu, L.; Gutul, T.; Todosiciuc, A.; Danila, M.; Muller, R.; Sarua, A.; Webster, R.; Tiginyanu, I.M.; Ursaki, V.

    2013-01-01

    InP nano dots with the diameter of 4-10 nm were synthesized using sol-gel method. The nano dot dimensions were obtained using TEM, and we found the d(111) spacing to be 0.328 nm which agrees within 3% of the literature value. Prepared nanoparticles where characterized then by Raman spectroscopy and Xray diffraction. Performed measurements confirm good crystalline quality of obtained InP particles, which can be used as a basis for THz emitters, LED, and OLED displays. (authors)

  9. Personal network (PN) applications

    DEFF Research Database (Denmark)

    Prasad, R.; Skouby, Knud Erik

    2005-01-01

    The applications of PN will be realised under many scenarios where users can have access to their personal network all the time. This network will enable the user to share critical information, play games, control their home remotely, etc. All this will be achieved with seamless interworking...... and handover between networks and user devices. This paper presents an array of use case scenarios that validates the ubiquitous usage of PN....

  10. Triple and Quadruple Junctions Thermophotovoltaic Devices Lattice Matched to InP

    Science.gov (United States)

    Bhusal, L.; Freundlich, A.

    2007-01-01

    Thermophotovoltaic (TPV) conversion of IR radiation emanating from a radioisotope heat source is under consideration for deep space exploration. Ideally, for radiator temperatures of interest, the TPV cell must convert efficiently photons in the 0.4-0.7 eV spectral range. Best experimental data for single junction cells are obtained for lattice-mismatched 0.55 eV InGaAs based devices. It was suggested, that a tandem InGaAs based TPV cell made by monolithically combining two or more lattice mismatched InGaAs subcells on InP would result in a sizeable efficiency improvement. However, from a practical standpoint the implementation of more than two subcells with lattice mismatch systems will require extremely thick graded layers (defect filtering systems) to accommodate the lattice mismatch between the sub-cells and could detrimentally affect the recycling of the unused IR energy to the emitter. A buffer structure, consisting of various InPAs layers, is incorporated to accommodate the lattice mismatch between the high and low bandgap subcells. There are evidences that the presence of the buffer structure may generate defects, which could extend down to the underlying InGaAs layer. The unusual large band gap lowering observed in GaAs(1-x)N(x) with low nitrogen fraction [1] has sparked a new interest in the development of dilute nitrogen containing III-V semiconductors for long-wavelength optoelectronic devices (e.g. IR lasers, detector, solar cells) [2-7]. Lattice matched Ga1-yInyNxAs1-x on InP has recently been investigated for the potential use in the mid-infrared device applications [8], and it could be a strong candidate for the applications in TPV devices. This novel quaternary alloy allows the tuning of the band gap from 1.42 eV to below 1 eV on GaAs and band gap as low as 0.6eV when strained to InP, but it has its own limitations. To achieve such a low band gap using the quaternary Ga1-yInyNxAs1-x, either it needs to be strained on InP, which creates further

  11. Agent-based Personal Network (PN) service architecture

    DEFF Research Database (Denmark)

    Jiang, Bo; Olesen, Henning

    2004-01-01

    In this paper we proposte a new concept for a centralized agent system as the solution for the PN service architecture, which aims to efficiently control and manage the PN resources and enable the PN based services to run seamlessly over different networks and devices. The working principle...

  12. Schottky barrier enhancement on n-InP solar cell applications

    DEFF Research Database (Denmark)

    Clausen, Thomas; Leistiko, Otto

    1994-01-01

    It is demonstrated that the Schottky barrier height on n-type InP can be enhanced to values close to the energy bandgap (1.35 eV) by employing a AuZnCr metallization. The process is simple and requires only mild and fast annealing sequences with temperatures not exceeding 500°C. Also, no critical...... epitaxial growth step of junctions is needed, making the process fairly cheap. Thus, prospects for an efficient and simple solar cell device structure for space application purposes based on highly radiant-resistant InP are greatly improved...

  13. InP quantum dots embedded in GaP: Optical properties and carrier dynamics

    International Nuclear Information System (INIS)

    Hatami, F.; Masselink, W.T.; Schrottke, L.; Tomm, J.W.; Talalaev, V.; Kristukat, C.; Goni, A.R.

    2003-01-01

    The optical emission and dynamics of carriers in Stranski-Krastanow self-organized InP quantum dots embedded in a GaP matrix are studied. InP deposited on GaP (001) using gas-source molecular-beam epitaxy forms quantum dots for InP coverage greater than 1.8 monolayers. Strong photoluminescence from the quantum dots is observed up to room temperature at about 2 eV; photoluminescence from the two-dimensional InP wetting layer is measured at about 2.2 eV. Modeling based on the 'model-solid theory' indicates that the band alignment for the InP quantum dots is direct and type I. Furthermore, low-temperature time-resolved photoluminescence measurements indicate that the carrier lifetime in the quantum dots is about 2 ns, typical for type-I quantum dots. Pressure-dependent photoluminescence measurements provide further evidence for a type-I band alignment for InP/GaP quantum dots at normal pressure with the GaP X states lying about 30 meV higher than the Γ states in the InP quantum dots, but indicate that they become type II under hydrostatic pressures of about 1.2 GPa

  14. 1.0 MeV irradiation of OHMIC, MS, MIS contacts to InP

    International Nuclear Information System (INIS)

    Warren, C.E.; Wagner, B.F.; Anderson, W.A.

    1986-01-01

    The radiation effects of 1.0 MeV electrons with a dose of 10/sup 15/cm/sup -2/ to MS and MIS Schottky diodes on InP have been compared to the radiation effects of MIS diodes on GaAs and Si. The radiation effects to ohmic contacts were also investigated. The metal for the diodes on the InP was gold. Au/Ti/Al was used for the GaAs diodes and Cr for the silicon diodes. Oxide layers on InP were grown by anodization in 0.1 N KOH. Oxides to GaAs and Si were grown thermally. Ohmic contacts to InP were formed using AuGe/Ni and AuSn alloys, followed by annealing in N/sub 2//H/sub 2/ (85%/15%). Metal Semiconductor diodes on InP were found to be at least sensitive to the irradiation. The InP MS and MIS diodes showed only small changes in the current voltage (I-V) characteristic, whereas the GaAs and Si devices showed a decrease in reverse current after irradiation. The ohmic contact resistance was increased by a factor of 2 to 5 after irradiation

  15. Single n+-i-n+ InP nanowires for highly sensitive terahertz detection.

    Science.gov (United States)

    Peng, Kun; Parkinson, Patrick; Gao, Qian; Boland, Jessica L; Li, Ziyuan; Wang, Fan; Mokkapati, Sudha; Fu, Lan; Johnston, Michael B; Tan, Hark Hoe; Jagadish, Chennupati

    2017-03-24

    Developing single-nanowire terahertz (THz) electronics and employing them as sub-wavelength components for highly-integrated THz time-domain spectroscopy (THz-TDS) applications is a promising approach to achieve future low-cost, highly integrable and high-resolution THz tools, which are desirable in many areas spanning from security, industry, environmental monitoring and medical diagnostics to fundamental science. In this work, we present the design and growth of n + -i-n + InP nanowires. The axial doping profile of the n + -i-n + InP nanowires has been calibrated and characterized using combined optical and electrical approaches to achieve nanowire devices with low contact resistances, on which the highly-sensitive InP single-nanowire photoconductive THz detectors have been demonstrated. While the n + -i-n + InP nanowire detector has a only pA-level response current, it has a 2.5 times improved signal-to-noise ratio compared with the undoped InP nanowire detector and is comparable to traditional bulk THz detectors. This performance indicates a promising path to nanowire-based THz electronics for future commercial applications.

  16. A fast and zero-biased photodetector based on GaTe-InSe vertical 2D p-n heterojunction

    Science.gov (United States)

    Feng, W.; Jin, Z.; Yuan, J.; Zhang, J.; Jia, S.; Dong, L.; Yoon, J.; Zhou, L.; Vajtai, R.; Tour, J. M.; Ajayan, P. M.; Hu, P.; Lou, J.

    2018-04-01

    p-n junctions serve as the building blocks for fundamental semiconductor devices, such as solar cells, light-emitting diodes (LEDs) and photodetectors. With recent studies unveiling the excellent optoelectronic properties of two-dimensional (2D) semiconductors, they are considered to be superb candidates for high performance p-n junctions. Here, we fabricate a vertical GaTe-InSe van der Waals (vdWs) p-n heterojunction by a PDMS-assisted transfer technique without etching. The fabricated p-n heterojunction shows gate-tunable current-rectifying behavior with a rectification factor reaching 1000. In addition, it features fast photodetection under zero bias as well as a high power conversion efficiency (PCE). Under 405 nm laser excitation, the zero-biased photodetector shows a high responsivity of 13.8 mA W-1 as well as a high external quantum efficiency (EQE) of 4.2%. Long-term stability is also observed and a response time of 20 µs is achieved due to stable and fast carrier transit through the built-in electric field in the depletion region. Fast and efficient charge separation in the vertical 2D p-n junction paves the way for developing 2D photodetectors with zero dark current, high speed and low power consumption.

  17. InP Heterojunction Bipolar Transistor Amplifiers to 255 GHz

    Science.gov (United States)

    Radisic, Vesna; Sawdai, Donald; Scott, Dennis; Deal, William; Dang, Linh; Li, Danny; Cavus, Abdullah; To, Richard; Lai, Richard

    2009-01-01

    Two single-stage InP heterojunction bipolar transistor (HBT) amplifiers operate at 184 and 255 GHz, using Northrop Grumman Corporation s InP HBT MMIC (monolithic microwave integrated circuit) technology. At the time of this reporting, these are reported to be the highest HBT amplifiers ever created. The purpose of the amplifier design is to evaluate the technology capability for high-frequency designs and verify the model for future development work.

  18. Vector grammars and PN machines

    Institute of Scientific and Technical Information of China (English)

    蒋昌俊

    1996-01-01

    The concept of vector grammars under the string semantic is introduced.The dass of vector grammars is given,which is similar to the dass of Chomsky grammars.The regular vector grammar is divided further.The strong and weak relation between the vector grammar and scalar grammar is discussed,so the spectrum system graph of scalar and vector grammars is made.The equivalent relation between the regular vector grammar and Petri nets (also called PN machine) is pointed.The hybrid PN machine is introduced,and its language is proved equivalent to the language of the context-free vector grammar.So the perfect relation structure between vector grammars and PN machines is formed.

  19. Porous InP as piezoelectric matrix material in 1-3 magnetoelectric composite sensors

    International Nuclear Information System (INIS)

    Gerngross, M.-D.; Leisner, M.; Carstensen, J.; Foell, H.

    2011-01-01

    This work shows the results of the fabrication of semi-insulating piezoelectric porous InP structures by electrochemical etching and subsequent purely chemical post-etching in an isotropic HF, HNO 3 , EtOH and HAc containing electrolyte. The piezoelectric modulus d 14 of porous InP is measured to around |60| pm / V, which larger by a factor of 30 compared to bulk InP.

  20. The temperature dependence of 1/f noise in InP

    NARCIS (Netherlands)

    Chen, X.Y.; Hooge, F.N.; Leijs, M.R.

    1997-01-01

    Noise spectra were measured on CBE grown InP samples in the frequency range from 1 Hz to 104 kHz at temperatures from 77 to 500 K. The experimental results show that llfnoise stems from the lattice scattering. The 1/f noise in InP is well characterised by a parameter CtL~,, in this temperature

  1. Electrochemical formation of InP porous nanostructures and its application to amperometric chemical sensors

    International Nuclear Information System (INIS)

    Sato, Taketomo; Mizohata, Akinori; Fujino, Toshiyuki; Hashizume, Tamotsu

    2008-01-01

    In this paper, we report the electrochemical formation of the InP porous nanostructures and their feasibility for the application to the amperometric chemical sensors. Our two step electrochemical process consists of the pore formation on a (001) n-type InP substrate and the subsequent etching of pore walls caused by changing the polarity of the InP electrode in a HCl-based electrolyte. By applying the anodic bias to the InP electrode, the high-density array of uniform nanopores was formed on the surface. Next, the cathodic bias was applied to the porous sample to reduce the wall thickness by cathodic decomposition of InP, where the thickness of InP nanowall decreased uniformly along the entire depth of the porous layer. From the amperometric measurements of the porous electrode, it was found that the electrocatalytic activity was much higher than that of the planar electrode. Furthermore, the current sensitivity for the H 2 O 2 detection was much enhanced after the cathodic decomposition process. The InP porous nanostructure formed by the present process is one of the promising structures for the application to the semiconductor-based bio/chemical sensors. (copyright 2008 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  2. Mapping Pn amplitude spreading and attenuation in Asia

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Xiaoning [Los Alamos National Laboratory; Phillips, William S [Los Alamos National Laboratory; Stead, Richard J [Los Alamos National Laboratory

    2010-12-06

    Pn travels most of its path in the mantle lid. Mapping the lateral variation of Pn amplitude attenuation sheds light on material properties and dynamics of the uppermost region of the mantle. Pn amplitude variation depends on the wavefront geometric spreading as well as material attenuation. We investigated Pn geometric spreading, which is much more complex than a traditionally assumed power-law spreading model, using both synthetic and observed amplitude data collected in Asia. We derived a new Pn spreading model based on the formulation that was proposed previously to account for the spherical shape of the Earth (Yang et. al., BSSA, 2007). New parameters derived for the spreading model provide much better correction for Pn amplitudes in terms of residual behavior. Because we used observed Pn amplitudes to construct the model, the model incorporates not only the effect of the Earth's spherical shape, but also the effect of potential upper-mantle velocity gradients in the region. Using the new spreading model, we corrected Pn amplitudes measured at 1, 2, 4 and 6 Hz and conducted attenuation tomography. The resulting Pn attenuation model correlates well with the regional geology. We see high attenuation in regions such as northern Tibetan Plateau and the western Pacific subduction zone, and low attenuation for stable blocks such as Sichuan and Tarim basins.

  3. An improved large signal model of InP HEMTs

    Science.gov (United States)

    Li, Tianhao; Li, Wenjun; Liu, Jun

    2018-05-01

    An improved large signal model for InP HEMTs is proposed in this paper. The channel current and charge model equations are constructed based on the Angelov model equations. Both the equations for channel current and gate charge models were all continuous and high order drivable, and the proposed gate charge model satisfied the charge conservation. For the strong leakage induced barrier reduction effect of InP HEMTs, the Angelov current model equations are improved. The channel current model could fit DC performance of devices. A 2 × 25 μm × 70 nm InP HEMT device is used to demonstrate the extraction and validation of the model, in which the model has predicted the DC I–V, C–V and bias related S parameters accurately. Project supported by the National Natural Science Foundation of China (No. 61331006).

  4. Oxidation of InP nanowires: a first principles molecular dynamics study.

    Science.gov (United States)

    Berwanger, Mailing; Schoenhalz, Aline L; Dos Santos, Cláudia L; Piquini, Paulo

    2016-11-16

    InP nanowires are candidates for optoelectronic applications, and as protective capping layers of III-V core-shell nanowires. Their surfaces are oxidized under ambient conditions which affects the nanowire physical properties. The majority of theoretical studies of InP nanowires, however, do not take into account the oxide layer at their surfaces. In this work we use first principles molecular dynamics electronic structure calculations to study the first steps in the oxidation process of a non-saturated InP nanowire surface as well as the properties of an already oxidized surface of an InP nanowire. Our calculations show that the O 2 molecules dissociate through several mechanisms, resulting in incorporation of O atoms into the surface layers. The results confirm the experimental observation that the oxidized layers become amorphous but the non-oxidized core layers remain crystalline. Oxygen related bonds at the oxidized layers introduce defective levels at the band gap region, with greater contributions from defects involving In-O and P-O bonds.

  5. A high-coverage nanoparticle monolayer for the fabrication of a subwavelength structure on InP substrates.

    Science.gov (United States)

    Kim, Dae-Seon; Park, Min-Su; Jang, Jae-Hyung

    2011-08-01

    Subwavelength structures (SWSs) were fabricated on the Indium Phosphide (InP) substrate by utilizing the confined convective self-assembly (CCSA) method followed by reactive ion etching (RIE). The surface condition of the InP substrate was changed by depositing a 30-nm-thick SiO2 layer and subsequently treating the surface with O2 plasma to achieve better surface coverage. The surface coverage of nanoparticle monolayer reached 90% by using O2 plasma-treated SiO2/InP substrate among three kinds of starting substrates such as the bare InP, SiO2/InP and O2 plasma-treated SiO2/InP substrate. A nanoparticle monolayer consisting of polystyrene spheres with diameter of 300 nm was used as an etch mask for transferring a two-dimensional periodic pattern onto the InP substrate. The fabricated conical SWS with an aspect ratio of 1.25 on the O2 plasma-treated SiO2/InP substrate exhibited the lowest reflectance. The average reflectance of the conical SWS was 5.84% in a spectral range between 200 and 900 nm under the normal incident angle.

  6. Performance, size, mass, and cost estimates for projected 1kW EOL Si, InP, and GaAs arrays

    Science.gov (United States)

    Slifer, Luther W., Jr.

    1991-01-01

    One method of evaluating the potential of emerging solar cell and array technologies is to compare their projected capabilities in space flight applications to those of established Si solar cells and arrays. Such an application-oriented comparison provides an integrated view of the elemental comparisons of efficiency, radiation resistance, temperature sensitivity, size, mass, and cost in combination. In addition, the assumptions necessary to make the comparisons provide insights helpful toward determining necessary areas of development or evaluation. Finally, as developments and evaluations progress, the results can be used in more precisely defining the overall potential of the new technologies in comparison to existing technologies. The projected capabilities of Si, InP, and GaAs cells and arrays are compared.

  7. Synthesis and structural characterization of the ternary Zintl phases AE3Al2Pn4 and AE3Ga2Pn4 (AE=Ca, Sr, Ba, Eu; Pn=P, As)

    International Nuclear Information System (INIS)

    He, Hua; Tyson, Chauntae; Saito, Maia; Bobev, Svilen

    2012-01-01

    Ten new ternary phosphides and arsenides with empirical formulae AE 3 Al 2 Pn 4 and AE 3 Ga 2 Pn 4 (AE=Ca, Sr, Ba, Eu; Pn=P, As) have been synthesized using molten Ga, Al, and Pb fluxes. They have been structurally characterized by single-crystal and powder X-ray diffraction to form with two different structures—Ca 3 Al 2 P 4 , Sr 3 Al 2 As 4 , Eu 3 Al 2 P 4 , Eu 3 Al 2 As 4 , Ca 3 Ga 2 P 4 , Sr 3 Ga 2 P 4 , Sr 3 Ga 2 As 4 , and Eu 3 Ga 2 As 4 crystallize with the Ca 3 Al 2 As 4 structure type (space group C2/c, Z=4); Ba 3 Al 2 P 4 and Ba 3 Al 2 As 4 adopt the Na 3 Fe 2 S 4 structure type (space group Pnma, Z=4). The polyanions in both structures are made up of TrPn 4 tetrahedra, which share common corners and edges to form 2 ∞ [TrPn 2 ] 3– layers in the phases with the Ca 3 Al 2 As 4 structure, and 1 ∞ [TrPn 2 ] 3– chains in Ba 3 Al 2 P 4 and Ba 3 Al 2 As 4 with the Na 3 Fe 2 S 4 structure type. The valence electron count for all of these compounds follows the Zintl–Klemm rules. Electronic band structure calculations confirm them to be semiconductors. - Graphical abstract: AE 3 Al 2 Pn 4 and AE 3 Ga 2 Pn 4 (AE=Ca, Sr, Ba, Eu; Pn=P, As) crystallize in two different structures—Ca 3 Al 2 P 4 , Sr 3 Al 2 As 4 , Eu 3 Al 2 P 4 , Eu 3 Al 2 As 4 , Ca 3 Ga 2 P 4 , Sr 3 Ga 2 P 4 , Sr 3 Ga 2 As 4 , and Eu 3 Ga 2 As 4 , are isotypic with the previously reported Ca 3 Al 2 As 4 (space group C2/c (No. 15)), while Ba 3 Al 2 P 4 and Ba 3 Al 2 As 4 adopt a different structure known for Na 3 Fe 2 S 4 (space group Pnma (No. 62). The polyanions in both structures are made up of TrPn 4 tetrahedra, which by sharing common corners and edges, form 2 ∞ [TrPn 2 ] 3– layers in the former and 1 ∞ [TrPn 2 ] 3– chains in Ba 3 Al 2 P 4 and Ba 3 Al 2 As 4 . Highlights: ► AE 3 Ga 2 Pn 4 (AE=Ca, Sr, Ba, Eu; Pn=P, As) are new ternary pnictides. ► Ba 3 Al 2 P 4 and Ba 3 Al 2 As 4 adopt the Na 3 Fe 2 S 4 structure type. ► The Sr- and Ca-compounds crystallize with the Ca 3

  8. Tumor protein 53-induced nuclear protein 1 (TP53INP1 enhances p53 function and represses tumorigenesis

    Directory of Open Access Journals (Sweden)

    Jeyran eShahbazi

    2013-05-01

    Full Text Available Tumor protein 53-induced nuclear protein 1 (TP53INP1 is a stress-induced p53 target gene whose expression is modulated by transcription factors such as p53, p73 and E2F1. TP53INP1 gene encodes two isoforms of TP53INP1 proteins, TP53INP1α and TP53INP1β, both of which appear to be key elements in p53 function. When associated with homeodomain-interacting protein kinase-2 (HIPK2, TP53INP1 phosphorylates p53 protein at Serine 46, enhances p53 protein stability and its transcriptional activity, leading to transcriptional activation of p53 target genes such as p21, PIG-3 and MDM2, cell growth arrest and apoptosis upon DNA damage stress. The anti-proliferative and pro-apoptotic activities of TP53INP1 indicate that TP53INP1 has an important role in cellular homeostasis and DNA damage response. Deficiency in TP53INP1 expression results in increased tumorigenesis; while TP53INP1 expression is repressed during early stages of cancer by factors such as miR-155. This review aims to summarize the roles of TP53INP1 in blocking tumor progression through p53-dependant and p53-independent pathways, as well as the elements which repress TP53INP1 expression, hence highlighting its potential as a therapeutic target in cancer treatment.

  9. InGaP Heterojunction Barrier Solar Cells

    Science.gov (United States)

    Welser, Roger E. (Inventor)

    2014-01-01

    A new solar cell structure called a heterojunction barrier solar cell is described. As with previously reported quantum-well and quantum-dot solar cell structures, a layer of narrow band-gap material, such as GaAs or indium-rich InGaP, is inserted into the depletion region of a wide band-gap PN junction. Rather than being thin, however, the layer of narrow band-gap material is about 400-430 nm wide and forms a single, ultrawide well in the depletion region. Thin (e.g., 20-50 nm), wide band-gap InGaP barrier layers in the depletion region reduce the diode dark current. Engineering the electric field and barrier profile of the absorber layer, barrier layer, and p-type layer of the PN junction maximizes photogenerated carrier escape. This new twist on nanostructured solar cell design allows the separate optimization of current and voltage to maximize conversion efficiency.

  10. Amorphization and recrystallization in MeV ion implanted InP crystals

    International Nuclear Information System (INIS)

    Xiong, F.; Nieh, C.W.; Jamieson, D.N.; Vreeland, T. Jr.; Tombrello, T.A.

    1988-01-01

    A comprehensive study of MeV- 15 N-ion-implanted InP by a variety of analytical techniques has revealed the physical processes involved in MeV ion implantation into III-V compound semiconductors as well as the influence of post-implantation annealing. It provides a coherent picture of implant distribution, structural transition, crystalline damage, and lattice strain in InP crystals induced by ion implantation and thermal annealing. The experimental results from the different measurements are summarized in this report. Mechanisms of amorphization by implantation and recrystallization through annealing in MeV-ion-implanted InP are proposed and discussed in light of the results obtained

  11. Role of pn-pairs in nuclear structure

    International Nuclear Information System (INIS)

    Nie, G.K.

    2003-01-01

    An α-cluster model of nuclear structure based on power of proton + neutron (pn)-pairs to bind themselves to α-clusters is proposed. The α-cluster is taken as the perfect condition of coupling of 2 pn- pairs, reminding complete electron shell in atomic physics. Pn-pairs create 2 other types of coupling of considerably less power between pn-pairs of nearby α-clusters ε α c and between pn-pair not bound into α-cluster with pn-pairs of nearby cluster ε pn c . Last two types of coupling are called covalent because of reminding similar electron coupling in chemistry. According the model nucleus is a liquid drop consisting of molecules, which are α-clusters, tied by covalent coupling with those ones which are in close vicinity. Then in case of even-even nuclei spin of the nucleus has to be zero I=0 + as sum of spinless particles. In case of nucleus has some nucleons (i) in intermolecular space, I=Σj i ; with taking into account that there is coupling of p and n in pn-pair. Therefore for 6 Li (1=0)I=2·1/2=1 + . The values ε α c , ε pn c and binding energy of the pn-pair itself ε pn have been estimated from analysis of binding energy of nuclei 6 Li, 10 B and 12 C. With the values the binding energy of the other nuclei with N=Z up to 58 Cu have been described with difference between experimental values and model ones in average less than 0.4 MeV. The structure reveals some regular forms, in which every cluster has reduced amount of covalent coupling, 3 or 4, and free pn-pair has 6 covalent coupling with 3 nearby clusters pn-pairs. Then the magic numbers are supposed to be the matter of geometry, when total amount of covalent couplings is optimal (minimal for the amount of clusters), α- clusters are placed in the same fixed distant from center of mass. It means that protons of the clusters can be considered as belonging to one shell. In the cluster model single particle effects have to be considered as single particle binding in one of the surface

  12. Channeling study of laser-induced defect generation in InP and InAs

    International Nuclear Information System (INIS)

    Burdel', K.K.; Kashkarov, P.K.; Timoshenko, V.Yu.; Chechenin, N.G.

    1992-01-01

    Damage production in InP and InAs single crystals induced by a ruby-laser pulse irradiation with τ p =20 ms in the energy density region W=0.05-1.0 J/cm 2 is studied by the channeling and Rutherford backscattering techniques. The defect generation threshold was determined to be equal to 0.2 J/cm 2 and 0.55 J/cm 2 for InP and InAs crystals, respectively. Stoichiometric defects in InP crystals were observed at W>=0.5 J/cm 2 . The temperature fields in InP and InAs under laser irradiation were calculated. The experimental observations are considered as a result of a selective evaporation of the components from the melt

  13. Enhanced light output from the nano-patterned InP semiconductor substrate through the nanoporous alumina mask.

    Science.gov (United States)

    Jung, Mi; Kim, Jae Hun; Lee, Seok; Jang, Byung Jin; Lee, Woo Young; Oh, Yoo-Mi; Park, Sun-Woo; Woo, Deokha

    2012-07-01

    A significant enhancement in the light output from nano-patterned InP substrate covered with a nanoporous alumina mask was observed. A uniform nanohole array on an InP semiconductor substrate was fabricated by inductively coupled plasma reactive ion etching (ICP-RIE), using the nanoporous alumina mask as a shadow mask. The light output property of the semiconductor substrate was investigated via photoluminescence (PL) intensity measurement. The InP substrate with a nanohole array showed a more enhanced PL intensity compared with the raw InP substrate without a nanohole structure. After ICP-RIE etching, the light output from the nanoporous InP substrate covered with a nanoporous alumina mask showed fourfold enhanced PL intensity compared with the raw InP substrate. These results can be used as a prospective method for increasing the light output efficiency of optoelectronic devices.

  14. Low temperature synthesis of InP nanocrystals

    International Nuclear Information System (INIS)

    Ung Thi Dieu Thuy; Tran Thi Thuong Huyen; Nguyen Quang Liem; Reiss, Peter

    2008-01-01

    We present a simple method for the chemical synthesis of InP nanocrystals, which comprises several advantages: (i) the use of simple reagents, namely InCl 3 .4H 2 O and yellow P as the In and P precursors, respectively, and NaBH 4 as the reducing agent in a mixed solvent of ethanol and toluene; (ii) a short reaction time (1-5 h) and low temperature (<75 deg. C); (iii) a high reaction yield approaching 100%. InP NCs in the zinc-blende structure have been obtained as confirmed by powder X-ray diffraction and Raman scattering measurements. Their mean size of 4 nm has been determined by transmission electron microscopy, Raman scattering and absorption spectroscopy

  15. Low energy Ar ion bombardment damage of Si, GaAs, and InP surfaces

    International Nuclear Information System (INIS)

    Williams, R.S.

    1982-01-01

    Argon bombardment damage to (100) surfaces of Si, GaAs, and InP for sputter ion-gun potentials of 1, 2, and 3 kilovolts was studied using Rutherford backscattering. Initial damage rates and saturation damage levels were determined. Bombardment damage sensitivity increased for the sequence Si, GaAs, and InP. Saturation damage levels for Si and GaAs correspond reasonably to LSS projected range plus standard deviation estimates; damage to InP exceeded this level significantly. For an ion-gun potential of 3 keV, the initial sputter yield of P from an InP surface exceeded the sputter yield of In by four atoms per incident Ar projectile. (author)

  16. Carrier concentration effects on radiation damage in InP

    International Nuclear Information System (INIS)

    Yamaguchi, M.; Ando, K.; Uemura, C.

    1984-01-01

    Minority carrier diffusion length and carrier concentration studies have been made on room-temperature 1-MeV electron irradiated liquid-encapsulated Czochralski grown Zn-doped p-InP. The damage rate for the diffusion length and carrier removal rate due to irradiation have been found to strongly decrease with an increase in the carrier concentration in InP. These phenomena suggest that the induced defects interact with impurities in InP. A preliminary study on the annealing behavior has also been performed

  17. Single Atomically Sharp Lateral Monolayer p-n Heterojunction Solar Cells with Extraordinarily High Power Conversion Efficiency

    KAUST Repository

    Tsai, Meng-Lin; Li, Ming-yang; Duran Retamal, Jose Ramon; Lam, Kai-Tak; Lin, Yung-Chang; Suenaga, Kazu; Chen, Lih-Juann; Liang, Gengchiau; Li, Lain-Jong; He, Jr-Hau

    2017-01-01

    The recent development of 2D monolayer lateral semiconductor has created new paradigm to develop p-n heterojunctions. Albeit, the growth methods of these heterostructures typically result in alloy structures at the interface, limiting

  18. Effect of Varying Pnictogen Elements (Pn=N, P, As, Sb, Bi) on the Optoelectronic Properties of SrZn2Pn2

    Science.gov (United States)

    Murtaza, G.; Yousaf, N.; Laref, A.; Yaseen, M.

    2018-03-01

    Pnictogen-based Zintl compounds have fascinating properties. Nowadays these compounds have gained exceptional interest in thermoelectric and optoelectronic fields. Therefore, in this work the structural, electronic and optical properties of SrZn2Pn2 (Pn=N, P, As, Sb, Bi) compounds were studied using state-of-the-art density functional theory. The optimised lattice parameters (ɑ, c, c/ɑ and bond lengths) are consistent with the experimental results. The bulk moduli and c/a showed a decrease when changing the Pnictogen (Pn) anion from N to Bi in SrZn2Pn2 (Pn=N, P, As, Sb, Bi). The modified Becke-Johnson potential is used for band structure calculations. All compounds show semiconducting behaviour except SrZn2Bi2, which is metallic. Pn-p, Zn-d and Sr-d play an important role in defining the electronic structure of the compounds. The optical conductivity and absorption coefficient strength are high in visible and ultraviolet regions. These band structures and optical properties clearly show that SrZn2Pn2 compounds are potential candidates in the fields of optoelectronic and photonic devices.

  19. Photoluminescence study of as-grown vertically standing wurtzite InP nanowire ensembles.

    Science.gov (United States)

    Iqbal, Azhar; Beech, Jason P; Anttu, Nicklas; Pistol, Mats-Erik; Samuelson, Lars; Borgström, Magnus T; Yartsev, Arkady

    2013-03-22

    We demonstrate a method that enables the study of photoluminescence of as-grown nanowires on a native substrate by non-destructively suppressing the contribution of substrate photoluminescence. This is achieved by using polarized photo-excitation and photoluminescence and by making an appropriate choice of incident angle of both excitation beam and photoluminescence collection direction. Using TE-polarized excitation at a wavelength of 488 nm at an incident angle of ∼70° we suppress the InP substrate photoluminescence relative to that of the InP nanowires by about 80 times. Consequently, the photoluminescence originating from the nanowires becomes comparable to and easily distinguishable from the substrate photoluminescence. The measured photoluminescence, which peaks at photon energies of ∼1.35 eV and ∼1.49 eV, corresponds to the InP substrate with zinc-blende crystal structure and to the InP nanowires with wurtzite crystal structure, respectively. The photoluminescence quantum yield of the nanowires was found to be ∼20 times lower than that of the InP substrate. The nanowires, grown vertically in a random ensemble, neither exhibit substantial emission polarization selectivity to the axis of the nanowires nor follow excitation polarization preferences observed previously for a single nanowire.

  20. Actinide-pnictide (An-Pn) bonds spanning non-metal, metalloid, and metal combinations (An=U, Th; Pn=P, As, Sb, Bi)

    Energy Technology Data Exchange (ETDEWEB)

    Rookes, Thomas M.; Wildman, Elizabeth P.; Gardner, Benedict M.; Wooles, Ashley J.; Gregson, Matthew; Tuna, Floriana; Liddle, Stephen T. [School of Chemistry, The University of Manchester (United Kingdom); Balazs, Gabor; Scheer, Manfred [Institute of Inorganic Chemistry, University of Regensburg (Germany)

    2018-01-26

    The synthesis and characterisation is presented of the compounds [An(Tren{sup DMBS}){Pn(SiMe_3)_2}] and [An(Tren{sup TIPS}){Pn(SiMe_3)_2}] [Tren{sup DMBS}=N(CH{sub 2}CH{sub 2}NSiMe{sub 2}Bu{sup t}){sub 3}, An=U, Pn=P, As, Sb, Bi; An=Th, Pn=P, As; Tren{sup TIPS}=N(CH{sub 2}CH{sub 2}NSiPr{sup i}{sub 3}){sub 3}, An=U, Pn=P, As, Sb; An=Th, Pn=P, As, Sb]. The U-Sb and Th-Sb moieties are unprecedented examples of any kind of An-Sb molecular bond, and the U-Bi bond is the first two-centre-two-electron (2c-2e) one. The Th-Bi combination was too unstable to isolate, underscoring the fragility of these linkages. However, the U-Bi complex is the heaviest 2c-2e pairing of two elements involving an actinide on a macroscopic scale under ambient conditions, and this is exceeded only by An-An pairings prepared under cryogenic matrix isolation conditions. Thermolysis and photolysis experiments suggest that the U-Pn bonds degrade by homolytic bond cleavage, whereas the more redox-robust thorium compounds engage in an acid-base/dehydrocoupling route. (copyright 2018 The Authors. Published by Wiley-VCH Verlag GmbH and Co. KGaA.)

  1. Low temperature synthesis of InP nanocrystals

    Energy Technology Data Exchange (ETDEWEB)

    Ung Thi Dieu Thuy [Institute of Materials Science (IMS), Vietnamese Academy of Science and Technology (VAST), 18 Hoang Quoc Viet, Cau Giay, Hanoi (Viet Nam); Tran Thi Thuong Huyen [Institute of Materials Science (IMS), Vietnamese Academy of Science and Technology (VAST), 18 Hoang Quoc Viet, Cau Giay, Hanoi (Viet Nam); National University of Thai Nguyen, 2 Luong Ngoc Quyen, Thai Nguyen (Viet Nam); Nguyen Quang Liem [Institute of Materials Science (IMS), Vietnamese Academy of Science and Technology (VAST), 18 Hoang Quoc Viet, Cau Giay, Hanoi (Viet Nam)], E-mail: liemnq@ims.vast.ac.vn; Reiss, Peter [DSM/INAC/SPrAM, UMR 5819 CEA-CNRS-Universite Joseph Fourier/LEMOH, CEA Grenoble, 17 rue des Martyrs, 38054 Grenoble Cedex 9 (France)

    2008-12-20

    We present a simple method for the chemical synthesis of InP nanocrystals, which comprises several advantages: (i) the use of simple reagents, namely InCl{sub 3}.4H{sub 2}O and yellow P as the In and P precursors, respectively, and NaBH{sub 4} as the reducing agent in a mixed solvent of ethanol and toluene; (ii) a short reaction time (1-5 h) and low temperature (<75 deg. C); (iii) a high reaction yield approaching 100%. InP NCs in the zinc-blende structure have been obtained as confirmed by powder X-ray diffraction and Raman scattering measurements. Their mean size of 4 nm has been determined by transmission electron microscopy, Raman scattering and absorption spectroscopy.

  2. Solar cells

    International Nuclear Information System (INIS)

    1980-01-01

    A method of producing solar cells is described which consists of producing a substantially monocrystalline tubular body of silicon or other suitable semiconductor material, treating this body to form an annular rectifying junction and then cutting it longitudinally to form a number of nearly flat ribbons from which the solar cells are fabricated. The P=N rectifying junction produced by the formation of silicon dioxide on the layers at the inner and outer surfaces of the body can be formed by ion-implantation or diffusion. (U.K.)

  3. Silicon fiber with p-n junction

    International Nuclear Information System (INIS)

    Homa, D.; Cito, A.; Pickrell, G.; Hill, C.; Scott, B.

    2014-01-01

    In this study, we fabricated a p-n junction in a fiber with a phosphorous doped silicon core and fused silica cladding. The fibers were fabricated via a hybrid process of the core-suction and melt-draw techniques and maintained overall diameters ranging from 200 to 900 μm and core diameters of 20–800 μm. The p-n junction was formed by doping the fiber with boron and confirmed via the current-voltage characteristic. The demonstration of a p-n junction in a melt-drawn silicon core fiber paves the way for the seamless integration of optical and electronic devices in fibers.

  4. Enhanced photovoltaic performance of an inclined nanowire array solar cell.

    Science.gov (United States)

    Wu, Yao; Yan, Xin; Zhang, Xia; Ren, Xiaomin

    2015-11-30

    An innovative solar cell based on inclined p-i-n nanowire array is designed and analyzed. The results show that the inclined geometry can sufficiently increase the conversion efficiency of solar cells by enhancing the absorption of light in the active region. By tuning the nanowire array density, nanowire diameter, nanowire length, as well as the proportion of intrinsic region of the inclined nanowire solar cell, a remarkable efficiency in excess of 16% can be obtained in GaAs. Similar results have been obtained in InP and Si nanowire solar cells, demonstrating the universality of the performance enhancement of inclined nanowire arrays.

  5. Palladium nanoparticles on InP for hydrogen detection

    Directory of Open Access Journals (Sweden)

    Zdansky Karel

    2011-01-01

    Full Text Available Abstract Layers of palladium (Pd nanoparticles on indium phosphide (InP were prepared by electrophoretic deposition from the colloid solution of Pd nanoparticles. Layers prepared by an opposite polarity of deposition showed different physical and morphological properties. Particles in solution are separated and, after deposition onto the InP surface, they form small aggregates. The size of the aggregates is dependent on the time of deposition. If the aggregates are small, the layer has no lateral conductance. Forward and reverse I-V characteristics showed a high rectification ratio with a high Schottky barrier height. The response of the structure on the presence of hydrogen was monitored.

  6. Low-fat, high-carbohydrate parenteral nutrition (PN) may potentially reverse liver disease in long-term PN-dependent infants

    DEFF Research Database (Denmark)

    Jakobsen, Marianne Skytte; Jørgensen, Marianne Hørby; Husby, Steffen

    2015-01-01

    INTRODUCTION: Parenteral nutrition-associated cholestasis (PNAC) is a complication of long-term parenteral nutrition (PN). Removal of lipids may reverse PNAC but compromises the energy to ensure infant growth. The purpose of this study was to test whether a low-fat, high-carbohydrate PN regimen......, which prevents and reverses PNAC in adults, could do the same in infants. This regimen could potentially avoid the problem of diminished energy input after removing nutritional lipids. METHODS: Infants developing PNAC over a 2-year period were started on a low-fat PN regimen with calories primarily from...

  7. Aqueous bromine etching of InP: a specific surface chemistry

    Energy Technology Data Exchange (ETDEWEB)

    Causier, A.; Bouttemy, M.; Gerard, I.; Aureau, D.; Vigneron, J.; Etcheberry, A. [Institut Lavoisier de Versailles, Versailles-Saint-Quentin University, UMR CNRS 8180, 45 Av. des Etats-Unis, 78035 Versailles (France)

    2012-06-15

    The n -InP behaviour in HBr (0.1-1.0 M)/Br{sub 2} (1.25 x 10{sup -2}M) aqueous solutions is studied by AAS, XPS and SEM-FEG. Indium AAS-titrations of the HBr/Br{sub 2} solutions demonstrate that InP undergoes an etching mechanism whatever the HBr/Br{sub 2} formulation. The etching process is always linear with time but its rate depends on the HBr concentration. XPS analyses permit to link the apparent slow-down of the dissolution process when decreasing the HBr molarity from 1.0 M to 0.1 M to the presence of a mixed (In,P){sub ox} oxide layer on the surface. Therefore, the dissolution process of InP in HBr/Br{sub 2} solution appears to be ruled by the surface chemical state (copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  8. Radiation resistant low bandgap InGaAsP solar cell for multi-junction solar cells

    International Nuclear Information System (INIS)

    Khan, Aurangzeb; Yamaguchi, Masafumi; Dharmaras, Nathaji; Yamada, Takashi; Tanabe, Tatsuya; Takagishi, Shigenori; Itoh, Hisayoshi; Ohshima, Takeshi

    2001-01-01

    We have explored the superior radiation tolerance of metal organic chemical vapor deposition (MOCVD) grown, low bandgap, (0.95eV) InGaAsP solar cells as compared to GaAs-on-Ge cells, after 1 MeV electron irradiation. The minority carrier injection due to forward bias and light illumination under low concentration ratio, can lead to enhanced recovery of radiation damage in InGaAsP n + -p junction solar cells. An injection anneal activation energy (0.58eV) of the defects involved in damage/recovery of the InGaAsP solar cells has been estimated from the resultant recovery of the solar cell properties following minority carrier injection. The results suggest that low bandgap radiation resistant InGaAsP (0.95eV) lattice matched to InP substrates provide an alternative to use as bottom cells in multi-junction solar cells instead of less radiation ressitant conventional GaAs based solar cells for space applications. (author)

  9. Diameter Dependence of Planar Defects in InP Nanowires.

    Science.gov (United States)

    Wang, Fengyun; Wang, Chao; Wang, Yiqian; Zhang, Minghuan; Han, Zhenlian; Yip, SenPo; Shen, Lifan; Han, Ning; Pun, Edwin Y B; Ho, Johnny C

    2016-09-12

    In this work, extensive characterization and complementary theoretical analysis have been carried out on Au-catalyzed InP nanowires in order to understand the planar defect formation as a function of nanowire diameter. From the detailed transmission electron microscopic measurements, the density of stacking faults and twin defects are found to monotonically decrease as the nanowire diameter is decreased to 10 nm, and the chemical analysis clearly indicates the drastic impact of In catalytic supersaturation in Au nanoparticles on the minimized planar defect formation in miniaturized nanowires. Specifically, during the chemical vapor deposition of InP nanowires, a significant amount of planar defects is created when the catalyst seed sizes are increased with the lower degree of In supersaturation as dictated by the Gibbs-Thomson effect, and an insufficient In diffusion (or Au-rich enhancement) would lead to a reduced and non-uniform In precipitation at the NW growing interface. The results presented here provide an insight into the fabrication of "bottom-up" InP NWs with minimized defect concentration which are suitable for various device applications.

  10. Silicon doped InP as an alternative plasmonic material for mid-infrared

    DEFF Research Database (Denmark)

    Panah, Mohammad Esmail Aryaee; Han, Li; Christensen, Dennis Valbjørn

    2016-01-01

    Silicon-doped InP is grown on top of semiinsulating iron-doped and sulfur-doped InP substrates by metalorganic vapor phase epitaxy (MOVPE), and the growth parameters are adjusted to obtain various free carrier concentrations from 1.05×1019 cm-3 up to 3.28×1019 cm-3. Midinfrared (IR) reflection...

  11. Ternary CaCu4P2-type pnictides AAg4Pn2 (A=Sr, Eu; Pn=As, Sb)

    Science.gov (United States)

    Stoyko, Stanislav S.; Khatun, Mansura; Scott Mullen, C.; Mar, Arthur

    2012-08-01

    Four ternary pnictides AAg4Pn2 (A=Sr, Eu; Pn=As, Sb) were prepared by reactions of the elements at 850 °C and their crystal structures were determined from single-crystal X-ray diffraction studies. These silver-containing pnictides AAg4Pn2 adopt the trigonal CaCu4P2-type structure (Pearson symbol hR21, space group R3¯m, Z=3; a=4.5555(6) Å, c=24.041(3) Å for SrAg4As2; a=4.5352(2) Å, c=23.7221(11) Å for EuAg4As2; a=4.7404(4) Å, c=25.029(2) Å for SrAg4Sb2; a=4.7239(3) Å, c=24.689(2) Å for EuAg4Sb2), which can be derived from the trigonal CaAl2Si2-type structure of the isoelectronic zinc-containing pnictides AZn2Pn2 by insertion of additional Ag atoms into trigonal planar sites within [M2Pn2]2- slabs built up of edge-sharing tetrahedra. Band structure calculations on SrAg4As2 and SrAg4Sb2 revealed that these charge-balanced Zintl phases actually exhibit no gap at the Fermi level and are predicted to be semimetals.

  12. ESCA and electron diffraction studies of InP surface heated under As molecular beam exposure

    International Nuclear Information System (INIS)

    Sugiura, Hideo; Yamaguchi, Masafumi; Shibukawa, Atsushi

    1983-01-01

    Chemical composition of InP substrate surface heattreated under As molecular beam exposure in an ultrahigh vacuum chamber was studied with ESCA, and surface reconstruction of the substrate was examined by in-situ electron diffraction. The InP substrate heated under the exposure of As molecular beam has mirror surface up to 590 0 C while the surface of InP heated above 400 0 C in vacuum is roughened. The ESCA study shows that thin InAs layer (thickness 0 C under the exposure of As. The electron diffraction study indicates that the InP is cleaned at about 500 0 C in As pressures of 10 -7 - 10 -5 Torr. The InP surface is prevented from thermally decomposing by the coverage of the InAs layer, which may be formed through the following process: 2InPO 4 + As 4 → 2InAs + P 2 O 5 + As 2 O 3 . (author)

  13. Electrical properties of bulk InP synthesized by modified horizontal Bridgman method

    International Nuclear Information System (INIS)

    Pak, K.; Matsui, M.; Fukuhara, H.; Nishinaga, T.; Nakamura, T.; Yasuda, Y.

    1986-01-01

    High purity polycrystalline InP has been required for preparation of starting materials in LEC pulling. Usually, these materials are synthesized by the horizontal Bridgman (HB) or gradient freeze (GF) method. The major problem for InP synthesis has been attributed to silicon contamination during the growth, as shown by several workers. In a previous paper, the authors proposed a model in which the silicon contamination would occur due to the transport of SiO and In/sub 2/O gas species from the In-P melt to the phosphorus region by the reaction of the melt with the quartz boat in the HB growth system and suggested that the Si concentration in the In-P melt would have an intimate correlation with the temperature in the phosphorus region. However, the effect of the temperature in the phosphorus region on the electrical properties has not been studied in details as of yet. In this note, a modified horizontal Bridgman (MHB) method was developed to reduce the residual donor impurities, and the reduction mechanism is discussed

  14. Fabrication and magnetic properties of granular Co/porous InP nanocomposite materials

    Directory of Open Access Journals (Sweden)

    Ma Li

    2011-01-01

    Full Text Available Abstract A novel Co/InP magnetic semiconductor nanocomposite was fabricated by electrodeposition magnetic Co nanoparticles into n-type porous InP templates in ethanol solution of cobalt chloride. The content or particle size of Co particles embedded in porous InP increased with increasing deposition time. Co particles had uniform distribution over pore sidewall surface of InP template, which was different from that of ceramic template and may open up new branch of fabrication of nanocomposites. The magnetism of such Co/InP nanocomposites can be gradually tuned from diamagnetism to ferromagnetism by increasing the deposition time of Co. Magnetic anisotropy of this Co/InP nanocomposite with magnetization easy axis along the axis of InP square channel was well realized by the competition between shape anisotropy and magnetocrystalline anisotropy. Such Co/InP nanocomposites with adjustable magnetism may have potential applications in future in the field of spin electronics. PACS: 61.46. +w · 72.80.Tm · 81.05.Rm · 75.75. +a · 82.45.Aa

  15. Fabrication and magnetic properties of granular Co/porous InP nanocomposite materials.

    Science.gov (United States)

    Zhou, Tao; Cheng, Dandan; Zheng, Maojun; Ma, Li; Shen, Wenzhong

    2011-03-31

    A novel Co/InP magnetic semiconductor nanocomposite was fabricated by electrodeposition magnetic Co nanoparticles into n-type porous InP templates in ethanol solution of cobalt chloride. The content or particle size of Co particles embedded in porous InP increased with increasing deposition time. Co particles had uniform distribution over pore sidewall surface of InP template, which was different from that of ceramic template and may open up new branch of fabrication of nanocomposites. The magnetism of such Co/InP nanocomposites can be gradually tuned from diamagnetism to ferromagnetism by increasing the deposition time of Co. Magnetic anisotropy of this Co/InP nanocomposite with magnetization easy axis along the axis of InP square channel was well realized by the competition between shape anisotropy and magnetocrystalline anisotropy. Such Co/InP nanocomposites with adjustable magnetism may have potential applications in future in the field of spin electronics.PACS: 61.46. +w · 72.80.Tm · 81.05.Rm · 75.75. +a · 82.45.Aa.

  16. Tailoring the optical characteristics of microsized InP nanoneedles directly grown on silicon.

    Science.gov (United States)

    Li, Kun; Sun, Hao; Ren, Fan; Ng, Kar Wei; Tran, Thai-Truong D; Chen, Roger; Chang-Hasnain, Connie J

    2014-01-08

    Nanoscale self-assembly offers a pathway to realize heterogeneous integration of III-V materials on silicon. However, for III-V nanowires directly grown on silicon, dislocation-free single-crystal quality could only be attained below certain critical dimensions. We recently reported a new approach that overcomes this size constraint, demonstrating the growth of single-crystal InGaAs/GaAs and InP nanoneedles with the base diameters exceeding 1 μm. Here, we report distinct optical characteristics of InP nanoneedles which are varied from mostly zincblende, zincblende/wurtzite-mixed, to pure wurtzite crystalline phase. We achieved, for the first time, pure single-crystal wurtzite-phase InP nanoneedles grown on silicon with bandgaps of 80 meV larger than that of zincblende-phase InP. Being able to attain excellent material quality while scaling up in size promises outstanding device performance of these nanoneedles. At room temperature, a high internal quantum efficiency of 25% and optically pumped lasing are demonstrated for single nanoneedle as-grown on silicon substrate. Recombination dynamics proves the excellent surface quality of the InP nanoneedles, which paves the way toward achieving multijunction photovoltaic cells, long-wavelength heterostructure lasers, and advanced photonic integrated circuits.

  17. Room-temperature annealing of Si implantation damage in InP

    International Nuclear Information System (INIS)

    Akano, U.G.; Mitchell, I.V.

    1991-01-01

    Spontaneous recovery at 295 K of Si implant damage in InP is reported. InP(Zn) and InP(S) wafers of (100) orientation have been implanted at room temperature with 600 keV Si + ions to doses ranging from 3.6x10 11 to 2x10 14 cm -2 . Room-temperature annealing of the resultant damage has been monitored by the Rutherford backscattering/channeling technique. For Si doses ≤4x10 13 cm -2 , up to 70% of the initial damage (displaced atoms) annealed out over a period of ∼85 days. The degree of recovery was found to depend on the initial level of damage. Recovery is characterized by at least two time constants t 1 2 ∼100 days. Anneal rates observed between 295 and 375 K are consistent with an activation energy of 1.2 eV, suggesting that the migration of implant-induced vacancies is associated with the reordering of the InP lattice

  18. Selective-area vapour-liquid-solid growth of InP nanowires

    International Nuclear Information System (INIS)

    Dalacu, Dan; Kam, Alicia; Guy Austing, D; Wu Xiaohua; Lapointe, Jean; Aers, Geof C; Poole, Philip J

    2009-01-01

    A comparison is made between the conventional non-selective vapour-liquid-solid growth of InP nanowires and a novel selective-area growth process where the Au-seeded InP nanowires grow exclusively in the openings of a SiO 2 mask on an InP substrate. This new process allows the precise positioning and diameter control of the nanowires required for future advanced device fabrication. The growth temperature range is found to be extended for the selective-area growth technique due to removal of the competition between material incorporation at the Au/nanowire interface and the substrate. A model describing the growth mechanism is presented which successfully accounts for the nanoparticle size-dependent and time-dependent growth rate. The dominant indium collection process is found to be the scattering of the group III source material from the SiO 2 mask and subsequent capture by the nanowire, a process that had previously been ignored for selective-area growth by chemical beam epitaxy.

  19. Selective-area vapour-liquid-solid growth of InP nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Dalacu, Dan; Kam, Alicia; Guy Austing, D; Wu Xiaohua; Lapointe, Jean; Aers, Geof C; Poole, Philip J, E-mail: dan.dalacu@nrc-cnrc.gc.c [Institute for Microstructural Sciences, National Research Council of Canada, Ottawa, K1A 0R6 (Canada)

    2009-09-30

    A comparison is made between the conventional non-selective vapour-liquid-solid growth of InP nanowires and a novel selective-area growth process where the Au-seeded InP nanowires grow exclusively in the openings of a SiO{sub 2} mask on an InP substrate. This new process allows the precise positioning and diameter control of the nanowires required for future advanced device fabrication. The growth temperature range is found to be extended for the selective-area growth technique due to removal of the competition between material incorporation at the Au/nanowire interface and the substrate. A model describing the growth mechanism is presented which successfully accounts for the nanoparticle size-dependent and time-dependent growth rate. The dominant indium collection process is found to be the scattering of the group III source material from the SiO{sub 2} mask and subsequent capture by the nanowire, a process that had previously been ignored for selective-area growth by chemical beam epitaxy.

  20. Reverse Current Characteristics of InP Gunn Diodes for W-Band Waveguide Applications.

    Science.gov (United States)

    Kim, Hyun-Seok; Heo, Jun-Woo; Chol, Seok-Gyu; Ko, Dong-Sik; Rhee, Jin-Koo

    2015-07-01

    InP is considered as the most promising material for millimeter-wave laser-diode applications owing to its superior noise performance and wide operating frequency range of 75-110 GHz. In this study, we demonstrate the fabrication of InP Gunn diodes with a current-limiting structure using rapid thermal annealing to modulate the potential height formed between an n-type InP active layer and a cathode contact. We also explore the reverse current characteristics of the InP Gunn diodes. Experimental results indicate a maximum anode current and an oscillation frequency of 200 mA and 93.53 GHz, respectively. The current-voltage characteristics are modeled by considering the Schottky and ohmic contacts, work function variations, negative differential resistance (NDR), and tunneling effect. Although no direct indication of the NDR is observed, the simulation results match the measured data well. The modeling results show that the NDR effect is always present but is masked because of electron emission across the shallow Schottky barrier.

  1. InP HEMT Integrated Circuits for Submillimeter Wave Radiometers in Earth Remote Sensing

    Science.gov (United States)

    Deal, William R.; Chattopadhyay, Goutam

    2012-01-01

    The operating frequency of InP integrated circuits has pushed well into the Submillimeter Wave frequency band, with amplification reported as high as 670 GHz. This paper provides an overview of current performance and potential application of InP HEMT to Submillimeter Wave radiometers for earth remote sensing.

  2. Electronic and magnetic properties of digitally Ti doped InP: A first principles study

    International Nuclear Information System (INIS)

    Rahman, Gul; Cho, Sunglae; Hong, Soon Cheol

    2008-01-01

    Using the full-potential linearized augmented plane wave method within the generalized gradient approximation, we study the electronic and the magnetic properties of digitally Ti doped InP. It is quite interesting that digitally Ti-doped InP system shows half metallic ferromagnetism even though both bulk zinc blende TiP and InP are paramagnetic. We also investigate the electronic and the magnetic properties as a function of spacer layer thickness. Their properties such as exchange coupling constant and atomic projected density of states are more or less independent of the InP thickness. Spin density contour maps indicate that the spin-polarization is confined within the TiP plane. The system may show a highly anisotropic property in spin-polarized transport. (copyright 2008 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  3. Twin and grain boundary in InP: A synchrotron radiation study

    International Nuclear Information System (INIS)

    Han, Y.; Liu, X.; Jiao, J.; Lin, L.; Jiang, J.; Wang, Z.; Tian, Y.

    1998-01-01

    Experimentally observed X-ray reflectivity curves show bi-crystal(twin) characteristics. The study revealed that there was defect segregation at the twin boundary. Stress was relaxed at the edge of the boundary. Relaxation of the stress resulted in formation of twin and other defects. As a result of formation of such defects, a defect-free and stress-free zone or low defect density and small stress zone is created around the defects. So a twin model was proposed to explain the experimental results. Stress(mainly thermal stress), chemical stoichiometry deviation and impurities nonhomogeneous distributions are the key factors that cause twins in LEC InP crystal growth. Twins on (111) face in LEC InP crystal were studied. Experimental evidence of above mentioned twin model and suggestions on how to get twin-free LEC InP single crystals will be discussed

  4. InP on SOI devices for optical communication and optical network on chip

    Science.gov (United States)

    Fedeli, J.-M.; Ben Bakir, B.; Olivier, N.; Grosse, Ph.; Grenouillet, L.; Augendre, E.; Phillippe, P.; Gilbert, K.; Bordel, D.; Harduin, J.

    2011-01-01

    For about ten years, we have been developing InP on Si devices under different projects focusing first on μlasers then on semicompact lasers. For aiming the integration on a CMOS circuit and for thermal issue, we relied on SiO2 direct bonding of InP unpatterned materials. After the chemical removal of the InP substrate, the heterostructures lie on top of silicon waveguides of an SOI wafer with a separation of about 100nm. Different lasers or photodetectors have been achieved for off-chip optical communication and for intra-chip optical communication within an optical network. For high performance computing with high speed communication between cores, we developed InP microdisk lasers that are coupled to silicon waveguide and produced 100μW of optical power and that can be directly modulated up to 5G at different wavelengths. The optical network is based on wavelength selective circuits with ring resonators. InGaAs photodetectors are evanescently coupled to the silicon waveguide with an efficiency of 0.8A/W. The fabrication has been demonstrated at 200mm wafer scale in a microelectronics clean room for CMOS compatibility. For off-chip communication, silicon on InP evanescent laser have been realized with an innovative design where the cavity is defined in silicon and the gain localized in the QW of bonded InP hererostructure. The investigated devices operate at continuous wave regime with room temperature threshold current below 100 mA, the side mode suppression ratio is as high as 20dB, and the fibercoupled output power is {7mW. Direct modulation can be achieved with already 6G operation.

  5. Boron profiles in doped amorphous-silicon solar cells formed by plasma ion deposition

    International Nuclear Information System (INIS)

    Stoddart, C.T.H.; Hunt, C.P.; Coleman, J.H.

    1979-01-01

    Amorphous silicon p-n junction solar cells of large area (100 cm 2 ) and having a quantum efficiency approaching 100% in the blue region have been prepared by plasma ion-plating, the p layer being formed from diborane and silane gases in a cathode glow-discharge. Surface secondary ion mass spectrometry combined with ion beam etching was found to be a very sensitive method with high in-depth resolution for obtaining the initial boron-silicon profile of the solar cell p-n junction. (author)

  6. InAs quantum wires on InP substrate for VCSEL applications

    OpenAIRE

    Lamy , Jean-Michel; Paranthoën , Cyril; Levallois , Christophe; Nakkar , Abdulhadi; Folliot , Hervé; Dehaese , Olivier; Le Corre , Alain; Loualiche , Slimane; Castany , Olivier; Dupont , Laurent

    2008-01-01

    International audience; Quantum dash based vertical cavity surface emitting lasers (VCSEL) on InP substrate are presented. Single and close stacking layers were successfully grown with molecular beam epitaxy. Optimized quantum dash layers exhibit a strong polarized 1.55 µm photoluminescence along the [1-10] crystallographic axis. Continuous wave laser emission is demonstrated at room temperature for the first time on a quantum dash VCSEL structure on InP susbtrate. The quantum dash VCSEL lase...

  7. Magnetic circular dichroism study of electron-irradiation induced defects in InP

    International Nuclear Information System (INIS)

    Gislason, H.P.

    1989-01-01

    A strong magnetic circular dichroism (MCD) absorption band centered at 1.07 eV in electron irradiated InP is reported. Temperature and magnetic field dependence of the signal reveal that the centre giving rise to this band is a spin triplet. By simulating neutral and reverse bias conditions of junction measurements through a careful choice of irradiation dose and starting material, the MCD band is shown to have an annealing behaviour closely resembling that of the majority carrier traps which control the Fermi level position in n- and p-type InP. The 1.07 eV MCD band represents the first magneto-optical signal connected with this family of complex irradiation-induced defects in InP. (author) 19 refs., 5 figs., 1 tab

  8. High Radiation Resistance IMM Solar Cell

    Science.gov (United States)

    Pan, Noren

    2015-01-01

    Due to high launch costs, weight reduction is a key driver for the development of new solar cell technologies suitable for space applications. This project is developing a unique triple-junction inverted metamorphic multijunction (IMM) technology that enables the manufacture of very lightweight, low-cost InGaAsP-based multijunction solar cells. This IMM technology consists of indium (In) and phosphorous (P) solar cell active materials, which are designed to improve the radiation-resistant properties of the triple-junction solar cell while maintaining high efficiency. The intrinsic radiation hardness of InP materials makes them of great interest for building solar cells suitable for deployment in harsh radiation environments, such as medium Earth orbit and missions to the outer planets. NASA Glenn's recently developed epitaxial lift-off (ELO) process also will be applied to this new structure, which will enable the fabrication of the IMM structure without the substrate.

  9. Anodic oxidation of InP in pure water

    International Nuclear Information System (INIS)

    Robach, Y.; Joseph, J.; Bergignat, E.; Hollinger, G.

    1989-01-01

    It is shown that thin InP native oxide films can be grown by anodization of InP in pure water. An interfacial phosphorus-rich In(PO 3 ) 3 -like condensed phosphate is obtained this way. This condensed phosphate has good passivating properties and can be used in electronic device technology. The chemical composition of these native oxides was found similar to that of an anodic oxide grown in an anodization in glycol and water (AGW) electrolyte. From the similarity between the two depth profiles observed in pure water and AGW electrolyte, they can conclude that dissolution phenomena do not seem to play a major role. The oxide growth seems to be controlled by the drift of ionic species under the electric field

  10. Ternary CaCu4P2-type pnictides AAg4Pn2 (A=Sr, Eu; Pn=As, Sb)

    International Nuclear Information System (INIS)

    Stoyko, Stanislav S.; Khatun, Mansura; Scott Mullen, C.; Mar, Arthur

    2012-01-01

    Four ternary pnictides AAg 4 Pn 2 (A=Sr, Eu; Pn=As, Sb) were prepared by reactions of the elements at 850 °C and their crystal structures were determined from single-crystal X-ray diffraction studies. These silver-containing pnictides AAg 4 Pn 2 adopt the trigonal CaCu 4 P 2 -type structure (Pearson symbol hR21, space group R3-bar m, Z=3; a=4.5555(6) Å, c=24.041(3) Å for SrAg 4 As 2 ; a=4.5352(2) Å, c=23.7221(11) Å for EuAg 4 As 2 ; a=4.7404(4) Å, c=25.029(2) Å for SrAg 4 Sb 2 ; a=4.7239(3) Å, c=24.689(2) Å for EuAg 4 Sb 2 ), which can be derived from the trigonal CaAl 2 Si 2 -type structure of the isoelectronic zinc-containing pnictides AZn 2 Pn 2 by insertion of additional Ag atoms into trigonal planar sites within [M 2 Pn 2 ] 2− slabs built up of edge-sharing tetrahedra. Band structure calculations on SrAg 4 As 2 and SrAg 4 Sb 2 revealed that these charge-balanced Zintl phases actually exhibit no gap at the Fermi level and are predicted to be semimetals. - Graphical abstract: SrAg 4 As 2 and related pnictides adopt a CaCu 4 P 2 -type structure in which additional Ag atoms enter trigonal planar sites within slabs built from edge-sharing tetrahedra. Highlights: ► AAg 4 Pn 2 are the first Ag-containing members of the CaCu 4 P 2 -type structure. ► Ag atoms are stuffed in trigonal planar sites within CaAl 2 Si 2 -type slabs. ► Ag–Ag bonding develops through attractive d 10 –d 10 interactions.

  11. Vapor-phase etching of InP using anhydrous HCl and PH/sub 3/ gas

    International Nuclear Information System (INIS)

    Pak, K.; Koide, Y.; Imai, K.; Yoshida, A.; Nakamura, T.; Yasuda, Y.; Nishinaga, T.

    1986-01-01

    In situ etching of the substrate surface for vapor-phase epitaxy is a useful technique for obtaining a smooth and damage-free surface prior to the growth. Previous work showed that the incorporation of in situ etching of InP substrate with anhydrous HCl gas resulted in a significant improvement in the surface morphologies for MOVPE-grown InGaAs/InP and InP epitaxial layers. However, the experiment on the HCl etching of the InP substrate for a wide temperature range has not been performed as yet. In this note, the authors describe the effect of the substrate temperature on the etching morphology of InP substrate by using the anhydrous HCl and PH/sub 3/ gases. In the experiment, they used a standard MOVPE horizontal system. A quartz reactor tube in a 60 mm ID, 60 cm long, was employed

  12. High resolution resonant Raman scattering in InP and GaAs

    International Nuclear Information System (INIS)

    Kernohan, E.T.M.

    1996-04-01

    Previous studies of III-V semiconductors using resonant Raman scattering have concentrated on measuring the variations in scattering intensity under different excitation conditions. The shape of the Raman line also contains important information, but this has usually been lost because the low signal strengths mean that resolution has been sacrificed for sensitivity. It might therefore be expected that further insights into the processes involved in Raman scattering could be obtained by using high resolution methods. In this thesis I have measured single- and multiple- phonon scattering from bulk GaAs and InP with a spectral resolution better than the intrinsic widths of the Raman lines. For scattering in the region of one longitudinal optic (LO) phonon energy, it is found that in InP the scattering in the allowed and forbidden configurations occur at different Raman shifts, above and below the zone-centre phonon energy respectively. These shifts are used to determine the scattering processes involved, and how they differ between InP and GaAs. The lineshapes obtained in multiple-phonon scattering are found to depend strongly on the excitation energy used, providing evidence for the presence of intermediate resonances. The measured spectra are used to provide information about the phonon dispersion of InP, whose dispersion it is difficult to measure in any other way, and the first evidence is found for an upward dispersion of the LO mode. Raman lineshapes are measured for InP in a magnetic field. The field alters the electronic bandstructure, leading to a series of strong resonances in the Raman efficiency due to interband magneto-optical transitions between Landau levels. This allows multiphonon processes up to sixth-order to be investigated. (author)

  13. Epitaxial growth and processing of InP films in a ``novel`` remote plasma-MOCVD apparatus

    Energy Technology Data Exchange (ETDEWEB)

    Bruno, G. [Bari Univ. (Italy). Centro di Studio per la Chimica; Losurdo, M. [Bari Univ. (Italy). Centro di Studio per la Chimica; Capezzuto, P. [Bari Univ. (Italy). Centro di Studio per la Chimica; Capozzi, V. [Bari Univ. (Italy). Ist. di Fisica; Lorusso, F.G. [Bari Univ. (Italy). Ist. di Fisica; Minafra, A. [Bari Univ. (Italy). Ist. di Fisica

    1996-06-01

    A new remote plasma MOCVD apparatus for the treatment and deposition of III-V materials and, specifically, of indium phosphide, has been developed. The plasma source is used to produce hydrogen atoms and to predissociate phosphine for, respectively, the reduction of native oxide on InP substrate surface and the InP deposition. In situ diagnostics by optical emission spectroscopy, mass spectrometry, and spectroscopic ellipsometry are used to fingerprint the gas phase and the growth surface. The plasma cleaning process effectively reduce the InP oxide layer without surface damage. Indium phosphide epilayers deposited from trimethylindium and plasma activated PH{sub 3} show singular photoluminescence spectra with signal intensity higher than that of the best InP film deposited under conventional MOCVD condition (without PH{sub 3} plasma preactivation). (orig.)

  14. Single-electron tunneling in InP nanowires

    NARCIS (Netherlands)

    Franceschi, De S.; Dam, Van J.A.; Bakkers, E.P.A.M.; Feiner, L.F.; Gurevich, L.; Kouwenhoven, L.P.

    2003-01-01

    A study was performed on single-electron tunneling in InP nanowires. The contact resistances as low as ~10 k¿, with minor temperature dependence were obtained. The Coulomb-blockade behavior was shown with single-electron charging energies of ~1 meV.

  15. InP membrane on silicon integration technology

    NARCIS (Netherlands)

    Smit, M.K.

    2013-01-01

    Integration of light sources in silicon photonics is usually done with an active InP-based layer stack on a silicon-based photonic circuit-layer. InP Membrane On Silicon (IMOS) technology integrates all functionality in a single InP-based layer.

  16. Assembly of phosphide nanocrystals into porous networks: formation of InP gels and aerogels.

    Science.gov (United States)

    Hitihami-Mudiyanselage, Asha; Senevirathne, Keerthi; Brock, Stephanie L

    2013-02-26

    The applicability of sol-gel nanoparticle assembly routes, previously employed for metal chalcogenides, to phosphides is reported for the case of InP. Two different sizes (3.5 and 6.0 nm) of InP nanoparticles were synthesized by solution-phase arrested precipitation, capped with thiolate ligands, and oxidized with H₂O₂ or O₂/light to induce gel formation. The gels were aged, solvent-exchanged, and then supercritically dried to obtain aerogels with both meso- (2-50 nm) and macropores (>50 nm) and accessible surface areas of ∼200 m²/g. Aerogels showed higher band gap values relative to precursor nanoparticles, suggesting that during the process of assembling nanoparticles into 3D architectures, particle size reduction may have taken place. In contrast to metal chalcogenide gelation, InP gels did not form using tetranitromethane, a non-oxygen-transferring oxidant. The requirement of an oxygen-transferring oxidant, combined with X-ray photoelectron spectroscopy data showing oxidized phosphorus, suggests gelation is occurring due to condensation of phosphorus oxoanionic moieties generated at the interfaces. The ability to link discrete InP nanoparticles into a 3D porous network while maintaining quantum confinement is expected to facilitate exploitation of nanostructured InP in solid-state devices.

  17. High microwave performance ion-implanted GaAs MESFETs on InP substrates

    International Nuclear Information System (INIS)

    Wada, M.; Kato, K.

    1990-01-01

    Ion implantation was employed, for the first time, in fabricating GaAs MESFETs in undoped 2 μm thick GaAs epitaxial layers directly grown on InP substrates by low-pressure MOVPE. The Si-ion-implanted GaAs layer on InP substrates showed excellent electrical characteristics: a mobility of 4300 cm 2 /Vs with a carrier density of 2 x 10 17 cm -3 at room temperature. The MESFET (0.8 μm gate length) exhibited a current-gain cutoff frequency of 25 GHz and a maximum frequency of oscillation of 53 GHz, the highest values yet reported to GaAs MESFETs on InP substrates. These results demonstrate the high potential of ion-implanted MESFETs as electronic devices for high-speed InP-based OEICs. (author)

  18. Titanium-dioxide nanotube p-n homojunction diode

    Science.gov (United States)

    Alivov, Yahya; Ding, Yuchen; Singh, Vivek; Nagpal, Prashant

    2014-12-01

    Application of semiconductors in functional optoelectronic devices requires precise control over their doping and formation of junction between p- and n-doped semiconductors. While doped thin films have led to several semiconductor devices, need for high-surface area nanostructured devices for photovoltaic, photoelectrochemical, and photocatalytic applications has been hindered by lack of desired doping in nanostructures. Here, we show titanium-dioxide (TiO2) nanotubes doped with nitrogen (N) and niobium (Nb) as acceptors and donors, respectively, and formation of TiO2 nanotubes p-n homojunction. This TiO2:N/TiO2:Nb homojunction showed distinct diode-like behaviour with rectification ratio of 1115 at ±5 V and exhibited good photoresponse for ultraviolet light (λ = 365 nm) with sensitivity of 0.19 A/W at reverse bias of -5 V. These results can have important implications for development of nanostructured metal-oxide solar-cells, photodiodes, LED's, photocatalysts, and photoelectrochemical devices.

  19. Titanium-dioxide nanotube p-n homojunction diode

    Energy Technology Data Exchange (ETDEWEB)

    Alivov, Yahya, E-mail: y.alivov@colorado.edu, E-mail: pnagpal@colorado.edu; Ding, Yuchen; Singh, Vivek [Department of Chemical and Biological Engineering, University of Colorado Boulder, 3415 Colorado Avenue, Boulder, Colorado 80303 (United States); Nagpal, Prashant, E-mail: y.alivov@colorado.edu, E-mail: pnagpal@colorado.edu [Department of Chemical and Biological Engineering, University of Colorado Boulder, 3415 Colorado Avenue, Boulder, Colorado 80303 (United States); Materials Science and Engineering, University of Colorado Boulder, 3415 Colorado Avenue, Boulder, Colorado 80303 (United States); Renewable and Sustainable Energy Institute, University of Colorado Boulder, 2445 Kittredge Loop, Boulder, Colorado 80309 (United States)

    2014-12-29

    Application of semiconductors in functional optoelectronic devices requires precise control over their doping and formation of junction between p- and n-doped semiconductors. While doped thin films have led to several semiconductor devices, need for high-surface area nanostructured devices for photovoltaic, photoelectrochemical, and photocatalytic applications has been hindered by lack of desired doping in nanostructures. Here, we show titanium-dioxide (TiO{sub 2}) nanotubes doped with nitrogen (N) and niobium (Nb) as acceptors and donors, respectively, and formation of TiO{sub 2} nanotubes p-n homojunction. This TiO{sub 2}:N/TiO{sub 2}:Nb homojunction showed distinct diode-like behaviour with rectification ratio of 1115 at ±5 V and exhibited good photoresponse for ultraviolet light (λ = 365 nm) with sensitivity of 0.19 A/W at reverse bias of −5 V. These results can have important implications for development of nanostructured metal-oxide solar-cells, photodiodes, LED's, photocatalysts, and photoelectrochemical devices.

  20. Electrical properties of InP irradiated by fast neutrons of a nuclear reactor

    International Nuclear Information System (INIS)

    Kolin, N.G.; Merkurisov, D.I.; Solov'ev, S.P.

    2000-01-01

    Electrophysical properties of InP single crystalline samples with different initial concentration of charge carriers have been studied in relation to irradiation conditions with fast neutrons of a nuclear reactor and subsequent heat treatments within the temperature range of 20-900 deg C. It has been shown that changes of the properties depend on the initial doping level. The annealing in the temperature range mentioned above results in the elimination of radiation defects. This makes possible to use the nuclear doping method for InP samples. In this respect the contribution of intermediate neutron reactions to the whole effect of the InP nuclear doping is estimated to be ∼ 10% [ru

  1. Surface protection during plasma hydrogenation for acceptor passivation in InP

    International Nuclear Information System (INIS)

    Lopata, J.; Dautremont-Smith, W.C.; Pearton, S.J.; Lee, J.W.; Ha, N.T.; Luftman, H.S.

    1990-01-01

    Various dielectric and metallic films were examined as H-permeable surface protection layers on InP during H 2 or D 2 plasma exposure for passivation of acceptors in the InP. Plasma deposited SiN x , SiO 2 , and a-Si(H) films ranging in thickness from 85 to 225 angstrom were used to protect p-InP during d 2 plasma exposure at 250 degrees C. Optimum protective layer thicknesses were determined by a trade-off between the effectiveness of the layer to prevent P loss from the wafer surface and the ability to diffuse atomic H or D at a rate greater than or equal to that in the underlying InP. SIMS and capacitance-voltage depth profiling were used to determine the extent of D in-diffusion and acceptor passivation respectively. Sputter deposited W and e-beam evaporated Ti films ∼100 Angstrom thick were also evaluated. The W coated sample yielded similar results to those with dielectric films in that acceptors in p-InP were passivated to a similar depth for the same plasma exposure. The 100 Angstrom Ti film, however, did not allow the D to diffuse into the InP substrate. It is surmised that the Ti film trapped the D, thus preventing diffusion into the substrate

  2. Thermal stability of atom configurations around Er atoms doped in InP by OMVPE

    International Nuclear Information System (INIS)

    Ofuchi, Hironori; Ito, Takashi; Kawamoto, Takeshi; Tabuchi, Masao; Fujiwara, Yasufumi; Takeda, Yoshikazu

    1999-01-01

    It has been found that there is a threshold growth temperature between 550 deg C and 580 deg C for the change of local structure around Er atoms in InP doped Er atoms grown by organometallic vapor phase epitaxy (OMVPE). To understand whether the structure change is induced at the growing surface or during the growth as an in situ annealing, the thermal stability of the local structures around the Er atoms doped in InP by the OMVPE at 530 deg C has been investigated by the extended X-ray absorption fine structure (EXAFS). The EXAFS analysis revealed that the local structure around the Er atoms, which existed substitutionally on In sites in the InP lattice, was stable against the post-growth annealing even for 1 h at 650 deg C. Therefore, it is concluded that the local structures are formed on the growth front, and not in the volume of InP by thermal annealing during or after the growth. (author)

  3. Synthesis and structural characterization of the Zintl phases Na{sub 3}Ca{sub 3}TrPn{sub 4}, Na{sub 3}Sr{sub 3}TrPn{sub 4}, and Na{sub 3}Eu{sub 3}TrPn{sub 4} (Tr=Al, Ga, In; Pn=P, As, Sb)

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Yi [Department of Chemistry & Biochemistry, University of Delaware, 304A Drake Hall, Newark, DE 19716 (United States); Suen, Nian-Tzu [Department of Chemistry & Biochemistry, University of Delaware, 304A Drake Hall, Newark, DE 19716 (United States); College of Chemistry and Chemical Engineering, Yangzhou University, Yangzhou 225002 (China); Kunene, Thabiso; Stoyko, Stanislav [Department of Chemistry & Biochemistry, University of Delaware, 304A Drake Hall, Newark, DE 19716 (United States); Bobev, Svilen, E-mail: bobev@udel.edu [Department of Chemistry & Biochemistry, University of Delaware, 304A Drake Hall, Newark, DE 19716 (United States)

    2017-05-15

    15 new quaternary Zintl phases have been synthesized by solid-state reactions from the respective elements, and their structures have been determined by single-crystal X-ray diffraction. Na{sub 3}E{sub 3}TrPn{sub 4} (E=Ca, Sr, Eu; Tr=Al, Ga, In; Pn=P, As, Sb) crystallize in the hexagonal crystal system with the non-centrosymmetric space group P6{sub 3}mc (No. 186). The structure represents a variant of the K{sub 6}HgS{sub 4} structure type (Pearson index hP22) and features [TrPn{sub 4}]{sup 9–} tetrahedral units, surrounded by Na{sup +} and Ca{sup 2+}, Sr{sup 2+}, Eu{sup 2+} cations. The nominal formula rationalization [Na{sup +}]{sub 3}[E{sup 2+}]{sub 3}[TrPn{sub 4}]{sup 9–} follows the octet rule, suggesting closed-shell configurations for all atoms and intrinsic semiconducting behavior. However, structure refinements for several members hint at disorder and mixing of cations that potentially counteract the optimal valence electron count. - Graphical abstract: The hexagonal, non-centrosymmetric structure of Na{sub 3}E{sub 3}TrPn{sub 4} (E=Ca, Sr, Eu; Tr=Al, Ga, In; Pn=P, As, Sb) features [TrPn{sub 4}]{sup 9–} tetrahedral units, surrounded by Na{sup +} and Ca{sup 2+}, Sr{sup 2+}, Eu{sup 2+} cations. - Highlights: • 15 quaternary phosphides, arsenides, and antimonides are synthesized and structurally characterized. • The structure is a variant of the hexagonal K{sub 6}HgS{sub 4}-type, with distinctive pattern for the cations. • Occupational and/or positional disorder of yet unknown origin exists for some members of the series.

  4. Chemically fixed p-n heterojunctions for polymer electronics by means of covalent B-F bond formation

    Science.gov (United States)

    Hoven, Corey V.; Wang, Huiping; Elbing, Mark; Garner, Logan; Winkelhaus, Daniel; Bazan, Guillermo C.

    2010-03-01

    Widely used solid-state devices fabricated with inorganic semiconductors, including light-emitting diodes and solar cells, derive much of their function from the p-n junction. Such junctions lead to diode characteristics and are attained when p-doped and n-doped materials come into contact with each other. Achieving bilayer p-n junctions with semiconducting polymers has been hindered by difficulties in the deposition of thin films with independent p-doped and n-doped layers. Here we report on how to achieve permanently fixed organic p-n heterojunctions by using a cationic conjugated polyelectrolyte with fluoride counteranions and an underlayer composed of a neutral conjugated polymer bearing anion-trapping functional groups. Application of a bias leads to charge injection and fluoride migration into the neutral layer, where irreversible covalent bond formation takes place. After the initial charging and doping, one obtains devices with no delay in the turn on of light-emitting electrochemical behaviour and excellent current rectification. Such devices highlight how mobile ions in organic media can open opportunities to realize device structures in ways that do not have analogies in the world of silicon and promise new opportunities for integrating organic materials within technologies now dominated by inorganic semiconductors.

  5. Modeling pN2 through Geological Time: Implications for Planetary Climates and Atmospheric Biosignatures.

    Science.gov (United States)

    Stüeken, E E; Kipp, M A; Koehler, M C; Schwieterman, E W; Johnson, B; Buick, R

    2016-12-01

    Nitrogen is a major nutrient for all life on Earth and could plausibly play a similar role in extraterrestrial biospheres. The major reservoir of nitrogen at Earth's surface is atmospheric N 2 , but recent studies have proposed that the size of this reservoir may have fluctuated significantly over the course of Earth's history with particularly low levels in the Neoarchean-presumably as a result of biological activity. We used a biogeochemical box model to test which conditions are necessary to cause large swings in atmospheric N 2 pressure. Parameters for our model are constrained by observations of modern Earth and reconstructions of biomass burial and oxidative weathering in deep time. A 1-D climate model was used to model potential effects on atmospheric climate. In a second set of tests, we perturbed our box model to investigate which parameters have the greatest impact on the evolution of atmospheric pN 2 and consider possible implications for nitrogen cycling on other planets. Our results suggest that (a) a high rate of biomass burial would have been needed in the Archean to draw down atmospheric pN 2 to less than half modern levels, (b) the resulting effect on temperature could probably have been compensated by increasing solar luminosity and a mild increase in pCO 2 , and (c) atmospheric oxygenation could have initiated a stepwise pN 2 rebound through oxidative weathering. In general, life appears to be necessary for significant atmospheric pN 2 swings on Earth-like planets. Our results further support the idea that an exoplanetary atmosphere rich in both N 2 and O 2 is a signature of an oxygen-producing biosphere. Key Words: Biosignatures-Early Earth-Planetary atmospheres. Astrobiology 16, 949-963.

  6. Composition and structure of ion-bombardment-induced growth cones on InP

    International Nuclear Information System (INIS)

    Malherbe, J.B.; Lakner, H.; Gries, W.H.

    1991-01-01

    The previously reported effect of low-energy (several keV) ion bombardment on the surface topography of InP was investigated by scanning transmission electron microscopy. Convergent beam electron diffraction patterns of the surface growth 'cones' induced by argon ion bombardment of (100) InP between 7 and 10 keV proved the cones to consist of crystalline InP (and not metallic indium, as has sometimes been claimed). The investigation showed that the irradiated surface region is not rendered completely amorphous but that it recrystallizes from the crystalline/amorphous interface in a columnar growth pattern, often terminating in growth cones protruding above the surface. Weak beam investigations revealed that the overwhelming majority of the cones have the orientation of the substrate. These phenomena were observed at all dose densities from 7 x 10 15 to 2 x 10 17 cm -2 . (author)

  7. n-p Short-Range Correlations from (p,2p+n) Measurements

    Science.gov (United States)

    Tang, A.; Watson, J. W.; Aclander, J.; Alster, J.; Asryan, G.; Averichev, Y.; Barton, D.; Baturin, V.; Bukhtoyarova, N.; Carroll, A.; Gushue, S.; Heppelmann, S.; Leksanov, A.; Makdisi, Y.; Malki, A.; Minina, E.; Navon, I.; Nicholson, H.; Ogawa, A.; Panebratsev, Yu.; Piasetzky, E.; Schetkovsky, A.; Shimanskiy, S.; Zhalov, D.

    2003-01-01

    We studied the 12C(p,2p+n) reaction at beam momenta of 5.9, 8.0, and 9.0 GeV/c. For quasielastic (p,2p) events pf, the momentum of the knocked-out proton before the reaction, was compared (event by event) with pn, the coincident neutron momentum. For |pn|>kF=0.220 GeV/c (the Fermi momentum) a strong back-to-back directional correlation between pf and pn was observed, indicative of short-range n-p correlations. From pn and pf we constructed the distributions of c.m. and relative motion in the longitudinal direction for correlated pairs. We also determined that 49±13% of events with |pf|>kF had directionally correlated neutrons with |pn|>kF.

  8. Structural analysis of erbium {delta}-doped InP by OMVPE with RBS-channeling

    Energy Technology Data Exchange (ETDEWEB)

    Yuhara, Junji; Takeda, Hitoshi; Matsubara, Naoki; Tabuchi, Masao; Fujiwara, Yasufumi; Morita, Kenji; Takeda, Yoshikazu [Nagoya Univ. (Japan). School of Engineering

    1997-03-01

    We have determined the lattice location of Er in InP {delta}-doped by OMVPE with RBS-channeling. Er concentrations along the <001> and <011> directions are same as random yields, while a significant flux peaking effect is seen for the <111> direction. These data suggest that Er atoms occupy the site equivalent to the hexahedral site in InP lattice. (author)

  9. Saturation broadening effect in an InP photonic-crystal nanocavity switch

    DEFF Research Database (Denmark)

    Yu, Yi; Palushani, Evarist; Heuck, Mikkel

    2014-01-01

    Pump-probe measurements on InP photonic-crystal nanocavities show large-contrast fast switching at low pulse energy. For large pulse energies, large resonance shifts passing across the probe lead to switching contrast saturation and switching time-window broadening. © 2014 OSA.......Pump-probe measurements on InP photonic-crystal nanocavities show large-contrast fast switching at low pulse energy. For large pulse energies, large resonance shifts passing across the probe lead to switching contrast saturation and switching time-window broadening. © 2014 OSA....

  10. Metastability of the phosphorus antisite defect in low-temperature InP

    International Nuclear Information System (INIS)

    Mikucki, J.; Baj, M.; Wasik, D.; Walukiewicz, W.; Bi, W. G.; Tu, C. W.

    2000-01-01

    We report on the transport properties of low-temperature (LT) InP/In x Ga 1-x As/InP heterostructures and LT InP thin films. Hall effect measurements performed at hydrostatic pressure up to 1.5 GPa and temperatures ranging from 4.2 K to 250 K on both types of samples as well as Shubnikov-de Haas experiments made on heterostructures clearly reveal the metastable character of phosphorus antisite defects present in LT InP layers. (c) 2000 The American Physical Society

  11. Oxide p-n Heterojunction of Cu2O/ZnO Nanowires and Their Photovoltaic Performance

    Directory of Open Access Journals (Sweden)

    Seung Ki Baek

    2013-01-01

    Full Text Available Oxide p-n heterojunction devices consisting of p-Cu2O/n-ZnO nanowires were fabricated on ITO/glass substrates and their photovoltaic performances were investigated. The vertically arrayed ZnO nanowires were grown by metal organic chemical vapor deposition, which was followed by the electrodeposition of the p-type Cu2O layer. Prior to the fabrication of solar cells, the effect of bath pH on properties of the absorber layers was studied to determine the optimal condition of the Cu2O electrodeposition process. With the constant pH 11 solution, the Cu2O layer preferred the (111 orientation, which gave low electrical resistivity and high optical absorption. The Cu2O (pH 11/ZnO nanowire-based solar cell exhibited a higher conversion efficiency of 0.27% than the planar structure solar cell (0.13%, because of the effective charge collection in the long wavelength region and because of the enhanced junction area.

  12. Budker INP in the LHC Machine (2)

    CERN Multimedia

    2001-01-01

    The main BINP contributions to the LHC machine are magnets for transfer lines (26 MCHF) and bus- bar sets (23 MCHF). Budker INP is also responsible for construction of some other LHC magnets and vacuum parts. In total, the contribution to the LHC machine will reach about 90 MCHF.

  13. Surface Plasmons on Highly Doped InP

    DEFF Research Database (Denmark)

    Panah, Mohammad Esmail Aryaee; Ottaviano, Luisa; Semenova, Elizaveta

    2016-01-01

    Silicon doped InP is grown by metal-organic vapor phase epitaxy (MOVPE) using optimized growth parameters to achieve high free carrier concentration. Reflectance of the grown sample in mid-IR range is measured using FTIR and the result is used to retrieve the parameters of the dielectric function...

  14. Influence of the cone angle and crystal shape on the formation of twins in InP crystals

    International Nuclear Information System (INIS)

    Li, Xiaolan; Yang, Ruixia; Yang, Fan; Sun, Tongnian; Sun, Niefeng

    2012-01-01

    We present the investigation of twinning phenomena of LEC InP crystal growth which has been carried out in our laboratory in recent years. It is observed that the yield of twin-free single crystal InP can be grown by control the cone angle and crystal shape of a gradually increased diameter. Twin formation has been correlated to many growth factors. The influence of ingot shape on the formation of twins can be looked as the conical angle dependent twin probability of InP crystals. Twin-free InP crystals can be grown by large cone angle over 75 to 90 . (copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  15. Temperature Dependence of Interband Transitions in Wurtzite InP Nanowires.

    Science.gov (United States)

    Zilli, Attilio; De Luca, Marta; Tedeschi, Davide; Fonseka, H Aruni; Miriametro, Antonio; Tan, Hark Hoe; Jagadish, Chennupati; Capizzi, Mario; Polimeni, Antonio

    2015-04-28

    Semiconductor nanowires (NWs) formed by non-nitride III-V compounds grow preferentially with wurtzite (WZ) lattice. This is contrary to bulk and two-dimensional layers of the same compounds, where only zincblende (ZB) is observed. The absorption spectrum of WZ materials differs largely from their ZB counterparts and shows three transitions, referred to as A, B, and C in order of increasing energy, involving the minimum of the conduction band and different critical points of the valence band. In this work, we determine the temperature dependence (T = 10-310 K) of the energy of transitions A, B, and C in ensembles of WZ InP NWs by photoluminescence (PL) and PL excitation (PLE) spectroscopy. For the whole temperature and energy ranges investigated, the PL and PLE spectra are quantitatively reproduced by a theoretical model taking into account contribution from both exciton and continuum states. WZ InP is found to behave very similarly to wide band gap III-nitrides and II-VI compounds, where the energy of A, B, and C displays the same temperature dependence. This finding unveils a general feature of the thermal properties of WZ materials that holds regardless of the bond polarity and energy gap of the crystal. Furthermore, no differences are observed in the temperature dependence of the fundamental band gap energy in WZ InP NWs and ZB InP (both NWs and bulk). This result points to a negligible role played by the WZ/ZB differences in determining the deformation potentials and the extent of the electron-phonon interaction that is a direct consequence of the similar nearest neighbor arrangement in the two lattices.

  16. Ultrafast recombination in H+ bombarded InP and GaAs: Consequences for the carrier distribution functions

    International Nuclear Information System (INIS)

    Lamprecht, K.F.; Juen, S.; Hoepfel, R.A.; Palmetshofer, L.

    1992-01-01

    The authors studied the lifetimes and the luminescence spectra of photoexcited carriers in H + bombarded InP and GaAs for different damage doses by means of femtosecond luminescence spectroscopy. For InP the lifetime decreases down to 95 fs for the highest dose, whereas for GaAs no shorter lifetime than 650 fs could be observed. With decreasing lifetime they observe an increase of the high energy tail of the time-integrated luminescence spectrum which is even inverted for the 95 fs InP sample

  17. InP and InAs nanowires hetero- and homojunctions: energetic stability and electronic properties.

    Science.gov (United States)

    Dionízio Moreira, M; Venezuela, P; Miwa, R H

    2010-07-16

    We performed an ab initio total energy investigation, within the density functional theory, of the energetic stability and the electronic properties of hydrogenated InAs/InP nanowire (NW) heterojunctions, as well as InAs and InP homojunctions composed of different structural arrangements, zinc-blend (zb) and wurtzite (w). For InAs/InP NW heterojunctions our results indicate that w and zb NW heterojunctions are quite similar, energetically, for thin NWs. We also examined the robustness of the abrupt interface through an atomic swap at the InAs/InP interface. Our results support the formation of abrupt (non-abrupt) interfaces in w (zb) InAs/InP heterojunctions. Concerning InAs/InP NW-SLs, our results indicate a type-I band alignment, with the energy barrier at the InP layers, in accordance with experimental works. For InAs or InP zb/w homojunctions, we also found a type-I band alignment for thin NWs, however, on increasing the NW diameter both InAs and InP homojunctions exhibit a type-II band alignment.

  18. InP and InAs nanowires hetero- and homojunctions: energetic stability and electronic properties

    International Nuclear Information System (INIS)

    Dionizio Moreira, M; Venezuela, P; Miwa, R H

    2010-01-01

    We performed an ab initio total energy investigation, within the density functional theory, of the energetic stability and the electronic properties of hydrogenated InAs/InP nanowire (NW) heterojunctions, as well as InAs and InP homojunctions composed of different structural arrangements, zinc-blend (zb) and wurtzite (w). For InAs/InP NW heterojunctions our results indicate that w and zb NW heterojunctions are quite similar, energetically, for thin NWs. We also examined the robustness of the abrupt interface through an atomic As↔P swap at the InAs/InP interface. Our results support the formation of abrupt (non-abrupt) interfaces in w (zb) InAs/InP heterojunctions. Concerning InAs/InP NW-SLs, our results indicate a type-I band alignment, with the energy barrier at the InP layers, in accordance with experimental works. For InAs or InP zb/w homojunctions, we also found a type-I band alignment for thin NWs, however, on increasing the NW diameter both InAs and InP homojunctions exhibit a type-II band alignment.

  19. Optical properties of Sulfur doped InP single crystals

    Science.gov (United States)

    El-Nahass, M. M.; Youssef, S. B.; Ali, H. A. M.

    2014-05-01

    Optical properties of InP:S single crystals were investigated using spectrophotometric measurements in the spectral range of 200-2500 nm. The absorption coefficient and refractive index were calculated. It was found that InP:S crystals exhibit allowed and forbidden direct transitions with energy gaps of 1.578 and 1.528 eV, respectively. Analysis of the refractive index in the normal dispersion region was discussed in terms of the single oscillator model. Some optical dispersion parameters namely: the dispersion energy (Ed), single oscillator energy (Eo), high frequency dielectric constant (ɛ∞), and lattice dielectric constant (ɛL) were determined. The volume and the surface energy loss functions (VELF & SELF) were estimated. Also, the real and imaginary parts of the complex conductivity were calculated.

  20. Effects of mask imperfections on InP etching profiles

    International Nuclear Information System (INIS)

    Huo, D.T.C.; Yan, M.F.; Wynn, J.D.; Wilt, D.P.

    1990-01-01

    The authors have demonstrated that the quality of etch masks has a significant effect on the InP etching profiles. In particular, the authors have shown that mask imperfections can cause defective etching profiles, such as vertical sidewalls and extra mask undercutting in InP. The authors also discovered that the geometry of these defective profiles is determined by the orientation of the substrate relative to the direction of the mask imperfections. Along a left-angle 110 right-angle line mask defect, the downward etching process changes the left-angle 110 right-angle v-grooves to vertical sidewalls without extra undercutting. For v-grooves aligned along the left-angle 110 right-angle direction, defects on the mask give a significant extra undercutting without changing the etching profile

  1. Band gap and band offset of (GaIn)(PSb) lattice matched to InP

    Science.gov (United States)

    Köhler, F.; Böhm, G.; Meyer, R.; Amann, M.-C.

    2005-07-01

    Metastable (GaxIn1-x)(PySb1-y) layers were grown on (001) InP substrates by gas source molecular beam epitaxy. Low-temperature photoluminescence spectroscopy was applied to these heterostructures and revealed spatially indirect band-to-band recombination of electrons localized in the InP with holes in the (GaxIn1-x)(PySb1-y). In addition, samples with layer thicknesses larger than 100nm showed direct PL across the band gap of (GaxIn1-x)(PySb1-y). Band-gap energies and band offset energies of (GaxIn1-x)(PySb1-y) relative to InP were derived from these PL data. A strong bowing parameter was observed.

  2. Dielectric properties of semi-insulating Fe-doped InP in the terahertz spectral region.

    Science.gov (United States)

    Alyabyeva, L N; Zhukova, E S; Belkin, M A; Gorshunov, B P

    2017-08-04

    We report the values and the spectral dependence of the real and imaginary parts of the dielectric permittivity of semi-insulating Fe-doped InP crystalline wafers in the 2-700 cm -1 (0.06-21 THz) spectral region at room temperature. The data shows a number of absorption bands that are assigned to one- and two-phonon and impurity-related absorption processes. Unlike the previous studies of undoped or low-doped InP material, our data unveil the dielectric properties of InP that are not screened by strong free-carrier absorption and will be useful for designing a wide variety of InP-based electronic and photonic devices operating in the terahertz spectral range.

  3. Molecular beam epitaxy of InxGa1-xAs on InP (100) substrates

    International Nuclear Information System (INIS)

    Dvoryankina, G.G.; Dvoryankin, V.F.; Petrov, A.G.; Kudryashov, A.A.; Khusid, L.B.

    1991-01-01

    Heteroepitaxy layers of In x Ga 1-x As in the wide field of compositions (x=0.2-0.8) of 0.2-2.0 μm thick on (100) InP substrates were grown using the methods of epitaxy from molecular beams. Structure, surface morphology and electric properties of layers in relation to their thick and composition were investigated. It was shown that the quality of In x Ga 1-x As layers on (100) InP was more sensitive to tensile strain than compressive strain. Different mechanisms of scattering of free electrons in layers of In x Ga 1-x As(x∼=0.53) on (101) InP were considered

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

    Science.gov (United States)

    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. Effect of Zinc Incorporation on the Performance of Red Light Emitting InP Core Nanocrystals.

    Science.gov (United States)

    Xi, Lifei; Cho, Deok-Yong; Besmehn, Astrid; Duchamp, Martial; Grützmacher, Detlev; Lam, Yeng Ming; Kardynał, Beata E

    2016-09-06

    This report presents a systematic study on the effect of zinc (Zn) carboxylate precursor on the structural and optical properties of red light emitting InP nanocrystals (NCs). NC cores were assessed using X-ray photoelectron spectroscopy (XPS), X-ray absorption spectroscopy (XAS), energy-dispersive X-ray spectroscopy (EDX), and high-resolution transmission electron microscopy (HRTEM). When moderate Zn:In ratios in the reaction pot were used, the incorporation of Zn in InP was insufficient to change the crystal structure or band gap of the NCs, but photoluminescence quantum yield (PLQY) increased dramatically compared with pure InP NCs. Zn was found to incorporate mostly in the phosphate layer on the NCs. PL, PLQY, and time-resolved PL (TRPL) show that Zn carboxylates added to the precursors during NC cores facilitate the synthesis of high-quality InP NCs by suppressing nonradiative and sub-band-gap recombination, and the effect is visible also after a ZnS shell is grown on the cores.

  6. Defects in mitophagy promote redox-driven metabolic syndrome in the absence of TP53INP1.

    Science.gov (United States)

    Seillier, Marion; Pouyet, Laurent; N'Guessan, Prudence; Nollet, Marie; Capo, Florence; Guillaumond, Fabienne; Peyta, Laure; Dumas, Jean-François; Varrault, Annie; Bertrand, Gyslaine; Bonnafous, Stéphanie; Tran, Albert; Meur, Gargi; Marchetti, Piero; Ravier, Magalie A; Dalle, Stéphane; Gual, Philippe; Muller, Dany; Rutter, Guy A; Servais, Stéphane; Iovanna, Juan L; Carrier, Alice

    2015-06-01

    The metabolic syndrome covers metabolic abnormalities including obesity and type 2 diabetes (T2D). T2D is characterized by insulin resistance resulting from both environmental and genetic factors. A genome-wide association study (GWAS) published in 2010 identified TP53INP1 as a new T2D susceptibility locus, but a pathological mechanism was not identified. In this work, we show that mice lacking TP53INP1 are prone to redox-driven obesity and insulin resistance. Furthermore, we demonstrate that the reactive oxygen species increase in TP53INP1-deficient cells results from accumulation of defective mitochondria associated with impaired PINK/PARKIN mitophagy. This chronic oxidative stress also favors accumulation of lipid droplets. Taken together, our data provide evidence that the GWAS-identified TP53INP1 gene prevents metabolic syndrome, through a mechanism involving prevention of oxidative stress by mitochondrial homeostasis regulation. In conclusion, this study highlights TP53INP1 as a molecular regulator of redox-driven metabolic syndrome and provides a new preclinical mouse model for metabolic syndrome clinical research. © 2015 The Authors. Published under the terms of the CC BY 4.0 license.

  7. Opto-electrical magnetic-field studies on solar silicon; Optoelektrische Magnetfelduntersuchungen an Solarsilizium

    Energy Technology Data Exchange (ETDEWEB)

    Buchwald, Rajko

    2010-05-21

    In the framework of this thesis opto-electrical studies on polycrystalline (pc) solar cells and solar materials have been performed. For this by magnetic-field topographical measurements the current distributions of the silicon samples were determined. For this the new, highly position-resolving magnetic-field measuring method CAIC has been developed and applied. The arrangement, the measurement principle, and the particularities of the method are explained. The results of the CAIC measurements have been compared with results of optical and electrical characterization methods, like the IR transmission-light microscopy, the LBIC, and the LIT method and evaluated. Special grain boundaries in the pc silicon samples with and without pn junction show photocurrent fluxes to the grain boundaries. On the base of the performed studies and the assumption of the existence of a grain-boundary decoration the current-flow model of an electrically active grain boundary is shown for a sample with pn junction as well as for a sample without pn junction. Furthermore macroscopical SiC and Si{sub 3}N{sub 4} precipitations in pc silicon were studied. By means of CAIC measurements hereby the position and the orientation of the conducting and near-surface precipitations could be determined. A current-flow model for macroscopic precipitations in silicon samples without pn junction is presented. Furthermore cell microcracks, failures in the contact structure and layout differences of the contact structure are uniquely detected by CAIC measurements on solar cells.

  8. [Managment system in safety and health at work organization. An Italian example in public sector: Inps].

    Science.gov (United States)

    Di Loreto, G; Felicioli, G

    2010-01-01

    The Istituto Nazionale della Previdenza Sociale (Inps) is one of the biggest Public Sector organizations in Italy; about 30.000 people work in his structures. Fifteen years ago, Inps launched a long term project with the objective to create a complex and efficient safety and health at work organization. Italian law contemplates a specific kind of physician working on safety and health at work, called "Medico competente", and 85 Inps's physicians work also as "Medico competente". This work describes how IT improved coordination and efficiency in this occupational health's management system.

  9. Time-of-flight neutron diffraction investigation of temperature factors in the Zn blende semiconductor InP

    International Nuclear Information System (INIS)

    Ferrari, C.; Bocchi, C.; Fornari, R.; Moze, O.; Wilson, C.C.

    1992-01-01

    A structural investigation of the Zn blende structure semiconductor InP has been carried out using the single crystal diffractometer SXD at the pulsed neutron facility ISIS. The ability to measure structure factors accurately at large Q values even with highly absorbing materials such as InP is demonstrated. Measurements were performed on a single crystal of InP at 293, 100 and 50 K with the crystallographic axis mounted perpendicular to the scattering plane. This enabled collection of (hhl) reflections up to a maximum with Miller indices (10, 10, 8). (orig.)

  10. AFM observation of OMVPE-grown ErP on InP substrates using a new organometal tris(ethylcyclopentadienyl)erbium (Er(EtCp)3)

    International Nuclear Information System (INIS)

    Akane, T.; Jinno, S.; Yang, Y.; Kuno, T.; Hirata, T.; Isogai, Y.; Watanabe, N.; Fujiwara, Y.; Nakamura, A.; Takeda, Y.

    2003-01-01

    ErP has been grown on InP(0 0 1) substrates by organometallic vapor phase epitaxy (OMVPE) using a new liquid organic Er source: tris(ethylcyclopentadienyl)erbium (Er(EtCp) 3 ). Morphological change of an ErP layer on InP(0 0 1) is investigated together with that of an overgrown capping InP layer. Optimum growth condition of InP causes islanding on over-monolayer-ErP. A relatively low overgrowth temperature of InP is a key factor for attaining complete capping coverage on ErP

  11. Bandgap Engineering of InP QDs Through Shell Thickness and Composition

    Energy Technology Data Exchange (ETDEWEB)

    Dennis, Allison M. [Los Alamos National Laboratory; Mangum, Benjamin D. [Los Alamos National Laboratory; Piryatinski, Andrei [Los Alamos National Laboratory; Park, Young-Shin [Los Alamos National Laboratory; Htoon, Han [Los Alamos National Laboratory; Hollingsworth, Jennifer A. [Los Alamos National Laboratory

    2012-06-21

    Fields as diverse as biological imaging and telecommunications utilize the unique photophysical and electronic properties of nanocrystal quantum dots (NQDs). The development of new NQD compositions promises material properties optimized for specific applications, while addressing material toxicity. Indium phosphide (InP) offers a 'green' alternative to the traditional cadmium-based NQDs, but suffers from extreme susceptibility to oxidation. Coating InP cores with more stable shell materials significantly improves nanocrystal resistance to oxidation and photostability. We have investigated several new InP-based core-shell compositions, correlating our results with theoretical predictions of their optical and electronic properties. Specifically, we can tailor the InP core-shell QDs to a type-I, quasi-type-II, or type-II bandgap structure with emission wavelengths ranging from 500-1300 nm depending on the shell material used (ZnS, ZnSe, CdS, or CdSe) and the thickness of the shell. Single molecule microscopy assessments of photobleaching and blinking are used to correlate NQD properties with shell thickness.

  12. Measurement of excitation functions and analysis of isomeric population in some reactions induced by proton on natural indium at low energy

    Science.gov (United States)

    Muhammed Shan, P. T.; Musthafa, M. M.; Najmunnisa, T.; Mohamed Aslam, P.; Rajesh, K. K.; Hajara, K.; Surendran, P.; Nair, J. P.; Shanbagh, Anil; Ghugre, S.

    2018-06-01

    The excitation functions for reaction residues populated via 115In(p , p) 115 mIn, 115In(p , pn) 114 mIn, 115In(p , p 2 n) 113 mIn, 113In(p , p) 113 mIn, 115In(p , nα) 111 mCd, 115In(p , 3 n) 113Sn and 113In(p , n) 113Sn channels were measured over the proton energy range of 8-22 MeV using stacked foil activation technique. Theoretical analysis of the data were performed within the framework of two statistical model codes EMPIRE-3.2 and TALYS-1.8. Isomeric cross section ratio for isomeric pairs m,g 115In, m,g 114In, m,g 113In, 113Sn m,g and m,g 111Cd were determined for the first time. The dependence of isomeric cross section ratio on various factors are analysed.

  13. Band Offsets and Interfacial Properties of HfAlO Gate Dielectric Grown on InP by Atomic Layer Deposition.

    Science.gov (United States)

    Yang, Lifeng; Wang, Tao; Zou, Ying; Lu, Hong-Liang

    2017-12-01

    X-ray photoelectron spectroscopy and high-resolution transmission electron microscopy have been used to determine interfacial properties of HfO 2 and HfAlO gate dielectrics grown on InP by atomic layer deposition. An undesirable interfacial InP x O y layer is easily formed at the HfO 2 /InP interface, which can severely degrade the electrical performance. However, an abrupt interface can be achieved when the growth of the HfAlO dielectric on InP starts with an ultrathin Al 2 O 3 layer. The valence and conduction band offsets for HfAlO/InP heterojunctions have been determined to be 1.87 ± 0.1 and 2.83 ± 0.1 eV, respectively. These advantages make HfAlO a potential dielectric for InP MOSFETs.

  14. Solar energy converters based on multi-junction photoemission solar cells.

    Science.gov (United States)

    Tereshchenko, O E; Golyashov, V A; Rodionov, A A; Chistokhin, I B; Kislykh, N V; Mironov, A V; Aksenov, V V

    2017-11-23

    Multi-junction solar cells with multiple p-n junctions made of different semiconductor materials have multiple bandgaps that allow reducing the relaxation energy loss and substantially increase the power-conversion efficiency. The choice of materials for each sub-cell is very limited due to the difficulties in extracting the current between the layers caused by the requirements for lattice- and current-matching. We propose a new vacuum multi-junction solar cell with multiple p-n junctions separated by vacuum gaps that allow using different semiconductor materials as cathode and anode, both activated to the state of effective negative electron affinity (NEA). In this work, the compact proximity focused vacuum tube with the GaAs(Cs,O) photocathode and AlGaAs/GaAs-(Cs,O) anode with GaAs quantum wells (QWs) is used as a prototype of a vacuum single-junction solar cell. The photodiode with the p-AlGaAs/GaAs anode showed the spectral power-conversion efficiency of about 1% at V bias  = 0 in transmission and reflection modes, while, at V bias  = 0.5 V, the efficiency increased up to 10%. In terms of energy conservation, we found the condition at which the energy cathode-to-anode transition was close to 1. Considering only the energy conservation part, the NEA-cell power-conversion efficiency can rich a quantum yield value which is measured up to more than 50%.

  15. Proposal of leak path passivation for InGaN solar cells to reduce the leakage current

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Ke, E-mail: ke.wang@chiba-u.jp; Imai, Daichi; Kusakabe, Kazuhide [Center for SMART Green Innovation Research, Chiba University, 1-33, Yayoi-cho, Inage-ku, Chiba 263-8522 (Japan); Yoshikawa, Akihiko, E-mail: yoshi@faculty.chiba-u.jp [Center for SMART Green Innovation Research, Chiba University, 1-33, Yayoi-cho, Inage-ku, Chiba 263-8522 (Japan); Department of Information and Communication Engineering, Graduate School of Engineering, Kogakuin University, Nakano-cho, Hachioji, Tokyo 2665-1 (Japan)

    2016-01-25

    We propose some general ways to passivate the leak paths in InGaN solar cells and report some experimental evidences of its effectiveness. By adopting an AlOx passivation process, the photovoltaic performances of GaN pn-junctions and InGaN solar cells, grown by molecular beam epitaxy, have been significantly improved. The open circuit voltage under 1 sun illumination increases from 1.46 to 2.26 V for a GaN pn junction, and from 0.95 to 1.27 V for an InGaN solar cell, demonstrating evidence of leak path passivation (LPP) by AlOx. The proposed LPP is expected to be a realistic way to exploit the potential of thick and relaxed but defective InGaN for solar cell applications.

  16. Switching dynamics in InP photonic-crystal nanocavity

    DEFF Research Database (Denmark)

    Yu, Yi; Palushani, Evarist; Heuck, Mikkel

    2016-01-01

    In this paper, we presented switching dynamic investigations on an InP photonic-crystal (PhC) nanocavity structure using homodyne pump-probe measurements. The measurements were compared with simulations based on temporal nonlinear coupled mode theory and carrier rate equations for the dynamics of...

  17. Two-dimensional non-volatile programmable p-n junctions

    Science.gov (United States)

    Li, Dong; Chen, Mingyuan; Sun, Zhengzong; Yu, Peng; Liu, Zheng; Ajayan, Pulickel M.; Zhang, Zengxing

    2017-09-01

    Semiconductor p-n junctions are the elementary building blocks of most electronic and optoelectronic devices. The need for their miniaturization has fuelled the rapid growth of interest in two-dimensional (2D) materials. However, the performance of a p-n junction considerably degrades as its thickness approaches a few nanometres and traditional technologies, such as doping and implantation, become invalid at the nanoscale. Here we report stable non-volatile programmable p-n junctions fabricated from the vertically stacked all-2D semiconductor/insulator/metal layers (WSe2/hexagonal boron nitride/graphene) in a semifloating gate field-effect transistor configuration. The junction exhibits a good rectifying behaviour with a rectification ratio of 104 and photovoltaic properties with a power conversion efficiency up to 4.1% under a 6.8 nW light. Based on the non-volatile programmable properties controlled by gate voltages, the 2D p-n junctions have been exploited for various electronic and optoelectronic applications, such as memories, photovoltaics, logic rectifiers and logic optoelectronic circuits.

  18. Applications of transient annealing to solar cell processing

    Energy Technology Data Exchange (ETDEWEB)

    Bentini, G.G. (C.N.R. Istituto LAMEL, Bologna (Italy))

    1983-01-01

    The economical reasons supporting the introduction of transient annealing in solar cell manufacturing are briefly discussed. Such techniques may play an important role, as they are compatible with the request of high throughput, automated processing together with the high quality of the p-n junction which are necessary for large scale economical production of photovoltaic energy. A survey of the applications of the different transient annealing techniques to solar cell processing has been developed by comparing in detail the results obtained up to now the case of solid and liquid phase transient annealing, associated with dry techniques such as Ion Implantation or dopant deposition on the wafer surface. The possibility of using laser pulses for the formation of the p-n junction by incorporation of dopant atoms from a suitable gaseous environment, has also been examined.

  19. N/P GaAs concentrator solar cells with an improved grid and bushbar contact design

    International Nuclear Information System (INIS)

    Desalvo, G.C.; Mueller, E.H.; Barnett, A.M.

    1985-01-01

    The major requirements for a solar cell used in space applications are high efficiency at AMO irradiance and resistance to high energy radiation. Gallium arsenide, with a band gap of 1.43 eV, is one of the most efficient sunlight to electricity converters (25%) when the the simple diode model is used to calculate efficiencies at AMO irradiance, GaAs solar cells are more radiation resistant than silicon solar cells and the N/P GaAs device has been reported to be more radiation resistant than similar P/N solar cells. This higher resistance is probably due to the fact that only 37% of the current is generated in the top N layer of the N/P cell compared to 69% in the top layer of a P/N solar cell. This top layer of the cell is most affected by radiation. It has also been theoretically calculated that the optimized N/P device will prove to have a higher efficiency than a similar P/N device. The use of a GaP window layer on a GaAs solar cell will avoid many of the inherent problems normally associated with a GaAlAs window while still proving good passivation of the GaAs surface. An optimized circular grid design for solar cell concentrators has been shown which incorporates a multi-layer metallization scheme. This multi-layer design allows for a greater current carrying capacity for a unit area of shading, which results in a better output efficiency

  20. Lattice location of diffused Zn atoms in GaAs and InP single crystals

    International Nuclear Information System (INIS)

    Chan, L.Y.; Yu, K.M.; Ben-Tzur, M.; Haller, E.E.; Jaklevic, J.M.; Walukiewicz, W.; Hanson, C.M.

    1991-01-01

    We have investigated the saturation phenomenon of the free carrier concentration in p-type GaAs and InP single crystals doped by zinc diffusion. The free hole saturation occurs at 10 20 cm -3 for GaAs, but the maximum concentration for InP appears at mid 10 18 cm -3 . The difference in the saturation hole concentrations for these materials is investigated by studying the incorporation and the lattice location of the impurity zinc, an acceptor when located on a group III atom site. Zinc is diffused into the III-V wafers in a sealed quartz ampoule. Particle-induced x-ray emission with ion-channeling techniques are employed to determine the exact lattice location of the zinc atoms. We have found that over 90% of all zinc atoms occupy Ga sites in the diffused GaAs samples, while for the InP case, the zinc substitutionality is dependent on the cooling rate of the sample after high-temperature diffusion. For the slowly cooled sample, a large fraction (∼90%) of the zinc atoms form random precipitates of Zn 3 P 2 and elemental Zn. However, when rapidly cooled only 60% of the zinc forms such precipitates while the rest occupies specific sites in the InP. We analyze our results in terms of the amphoteric native defect model. We show that the difference in the electrical activity of the Zn atoms in GaAs and InP is a consequence of the different location of the Fermi level stabilization energy in these two materials

  1. Questionable effects of antireflective coatings on inefficiently cooled solar cells

    DEFF Research Database (Denmark)

    Akhmatov, Vladislav; Galster, Georg; Larsen, Esben

    1998-01-01

    of the output power and efficiency curves throughout the day the coherence between technical parameters of the solar cells and the climate in the operation region is observed and examined. It is shown how the drop in output power around noon can be avoided by fitting technical parameters of the solar cells......A model for temperature effects in p-n junction solar cells is introduced. The temperature of solar cells and the losses in the solar cell junction region caused by elevating temperature are discussed. The model developed is examined for low-cost silicon solar cells. In order to improve the shape...

  2. Radiation defects in electron-irradiated InP crystals

    International Nuclear Information System (INIS)

    Brailovskii, E.Yu.; Karapetyan, F.K.; Megela, I.G.; Tartachnik, V.P.

    1982-01-01

    The results are presented of formation and annealing of defects in InP crystals at 1 to 50 MeV electron irradiation. The recovery of electrical properties in the range of 77 to 970 K during annealing processes is studied. Five low temperature annealing states in n-InP and the reverse annealing in p-InP are observed at 77 to 300 K. Four annealing stages at temperatures higher than 300 K are present. When the electron energy is increased more complicated thermostable defects are formed, and at 50 MeV electron energy besides of the point defect clusters are formed, which anneal at temperatures of 800 to 970 K. It is shown that the peculiarities of the Hall mobility at irradiation and annealing are caused by the scattering centres E/sub c/ - 0.2 eV. The 'limiting' position of the Fermi level in electron irradiated InP crystals is discussed. (author)

  3. Radiation defects in electron-irradiated InP crystals

    Energy Technology Data Exchange (ETDEWEB)

    Brailovskii, E.Yu.; Karapetyan, F.K.; Megela, I.G.; Tartachnik, V.P. (AN Ukrainskoj SSR, Kiev. Inst. Yadernykh Issledovanij)

    1982-06-16

    The results are presented of formation and annealing of defects in InP crystals at 1 to 50 MeV electron irradiation. The recovery of electrical properties in the range of 77 to 970 K during annealing processes is studied. Five low temperature annealing states in n-InP and the reverse annealing in p-InP are observed at 77 to 300 K. Four annealing stages at temperatures higher than 300 K are present. When the electron energy is increased more complicated thermostable defects are formed, and at 50 MeV electron energy besides of the point defect clusters are formed, which anneal at temperatures of 800 to 970 K. It is shown that the peculiarities of the Hall mobility at irradiation and annealing are caused by the scattering centres E/sub c/ - 0.2 eV. The 'limiting' position of the Fermi level in electron irradiated InP crystals is discussed.

  4. Design and modeling of InP DHBT power amplifiers at millimeter-wave frequencies

    DEFF Research Database (Denmark)

    Yan, Lei; Johansen, Tom K.

    2012-01-01

    In this paper, the design and modeling of InP DHBT based millimeter-wave(mm-wave) power amplifiers is described. This includes the modeling of InP DHBT devices and layout parasitics. An EM-circuit co-simulation approach is described to allow all parasitics to be modeled for accurate circuit...... demonstrates a power gain of 4.5dB with a saturated output power of 14.2dBm at 69.2GHz. © 2012 European Microwave Assoc....

  5. Inverse metal-assisted chemical etching produces smooth high aspect ratio InP nanostructures.

    Science.gov (United States)

    Kim, Seung Hyun; Mohseni, Parsian K; Song, Yi; Ishihara, Tatsumi; Li, Xiuling

    2015-01-14

    Creating high aspect ratio (AR) nanostructures by top-down fabrication without surface damage remains challenging for III-V semiconductors. Here, we demonstrate uniform, array-based InP nanostructures with lateral dimensions as small as sub-20 nm and AR > 35 using inverse metal-assisted chemical etching (I-MacEtch) in hydrogen peroxide (H2O2) and sulfuric acid (H2SO4), a purely solution-based yet anisotropic etching method. The mechanism of I-MacEtch, in contrast to regular MacEtch, is explored through surface characterization. Unique to I-MacEtch, the sidewall etching profile is remarkably smooth, independent of metal pattern edge roughness. The capability of this simple method to create various InP nanostructures, including high AR fins, can potentially enable the aggressive scaling of InP based transistors and optoelectronic devices with better performance and at lower cost than conventional etching methods.

  6. Formation of nanogaps in InAs nanowires by selectively etching embedded InP segments.

    Science.gov (United States)

    Schukfeh, M I; Storm, K; Hansen, A; Thelander, C; Hinze, P; Beyer, A; Weimann, T; Samuelson, L; Tornow, M

    2014-11-21

    We present a method to fabricate nanometer scale gaps within InAs nanowires by selectively etching InAs/InP heterostructure nanowires. We used vapor-liquid-solid grown InAs nanowires with embedded InP segments of 10-60 nm length and developed an etching recipe to selectively remove the InP segment. A photo-assisted wet etching process in a mixture of acetic acid and hydrobromic acid gave high selectivity, with accurate removal of InP segments down to 20 nm, leaving the InAs wire largely unattacked, as verified using scanning electron and transmission electron microscopy. The obtained nanogaps in InAs wires have potential as semiconducting electrodes to investigate electronic transport in nanoscale objects. We demonstrate this functionality by dielectrophoretically trapping 30 nm diameter gold nanoparticles into the gap.

  7. Formation of nanogaps in InAs nanowires by selectively etching embedded InP segments

    International Nuclear Information System (INIS)

    Schukfeh, M I; Hansen, A; Tornow, M; Storm, K; Thelander, C; Samuelson, L; Hinze, P; Weimann, T; Beyer, A

    2014-01-01

    We present a method to fabricate nanometer scale gaps within InAs nanowires by selectively etching InAs/InP heterostructure nanowires. We used vapor–liquid–solid grown InAs nanowires with embedded InP segments of 10–60 nm length and developed an etching recipe to selectively remove the InP segment. A photo-assisted wet etching process in a mixture of acetic acid and hydrobromic acid gave high selectivity, with accurate removal of InP segments down to 20 nm, leaving the InAs wire largely unattacked, as verified using scanning electron and transmission electron microscopy. The obtained nanogaps in InAs wires have potential as semiconducting electrodes to investigate electronic transport in nanoscale objects. We demonstrate this functionality by dielectrophoretically trapping 30 nm diameter gold nanoparticles into the gap. (paper)

  8. Segregation of antimony in InP in MOVPE

    Energy Technology Data Exchange (ETDEWEB)

    Weeke, Stefan

    2008-07-01

    In this work the segregation of antimony in indium phosphide in metal organic vapour phase epitaxy (MOVPE)was systematically investigated. Therefore phosphine stabilized InP surfaces were treated with tri-methyl-antimony (TMSb) in MOVPE. An antimony rich Sb/InP surface was established, showing a typical spectra for the antimonides observed in reflectance anisotropy spectroscopy (RAS).Adsorption and desorption of antimony are investigated, as well as the incorporation of Sb during overgrowth of the Sb/InP surface with InP. Therefore the growth parameters temperature, TMSb partial pressure and treatment time are varied and their influence investigated. The experiments are monitored in-situ with RAS, the achieved data is correlated with ex-situ characterisation such as X-ray diffraction (XRD) and secondary ion mass spectroscopy (SIMS). It is shown that under treatment with TMSb a stable Sb/InP surface is formed within seconds, which does not change under further TMSb treatment. This process is rarely influenced by the TMSb partial pressure. On the contrary, the desorption of Sb is a very slow process. Two main processes can be distinguished: The desorption of excess Sb from the surface and the formation of the MOVPE prepared InP (2 x 1) surface. The reaction velocity of adsorption and desorption increases with temperature. Above a critical value the increase of TMSb partial pressure has no influence on the time for desorption. During overgrowth of the Sb/InP surface the opposite temperature dependence is observed: with increasing growth temperature the typical spectra for antimonides is observed longer. An analysis of the grown samples with XRD and SIMS showed the formation of an InPSb double quantum well. One layer is formed at the interface, the second one 50 nm-120 nm deep in the InP. The location of the 2nd InPSb layer can be correlated with the vanishing of the Sb signature in RAS. The distance between the quantum wells increases with growth temperature, until it

  9. Segregation of antimony in InP in MOVPE

    International Nuclear Information System (INIS)

    Weeke, Stefan

    2008-01-01

    In this work the segregation of antimony in indium phosphide in metal organic vapour phase epitaxy (MOVPE)was systematically investigated. Therefore phosphine stabilized InP surfaces were treated with tri-methyl-antimony (TMSb) in MOVPE. An antimony rich Sb/InP surface was established, showing a typical spectra for the antimonides observed in reflectance anisotropy spectroscopy (RAS).Adsorption and desorption of antimony are investigated, as well as the incorporation of Sb during overgrowth of the Sb/InP surface with InP. Therefore the growth parameters temperature, TMSb partial pressure and treatment time are varied and their influence investigated. The experiments are monitored in-situ with RAS, the achieved data is correlated with ex-situ characterisation such as X-ray diffraction (XRD) and secondary ion mass spectroscopy (SIMS). It is shown that under treatment with TMSb a stable Sb/InP surface is formed within seconds, which does not change under further TMSb treatment. This process is rarely influenced by the TMSb partial pressure. On the contrary, the desorption of Sb is a very slow process. Two main processes can be distinguished: The desorption of excess Sb from the surface and the formation of the MOVPE prepared InP (2 x 1) surface. The reaction velocity of adsorption and desorption increases with temperature. Above a critical value the increase of TMSb partial pressure has no influence on the time for desorption. During overgrowth of the Sb/InP surface the opposite temperature dependence is observed: with increasing growth temperature the typical spectra for antimonides is observed longer. An analysis of the grown samples with XRD and SIMS showed the formation of an InPSb double quantum well. One layer is formed at the interface, the second one 50 nm-120 nm deep in the InP. The location of the 2nd InPSb layer can be correlated with the vanishing of the Sb signature in RAS. The distance between the quantum wells increases with growth temperature, until it

  10. Design and Simulation of InGaN p-n Junction Solar Cell

    Directory of Open Access Journals (Sweden)

    A. Mesrane

    2015-01-01

    Full Text Available The tunability of the InGaN band gap energy over a wide range provides a good spectral match to sunlight, making it a suitable material for photovoltaic solar cells. The main objective of this work is to design and simulate the optimal InGaN single-junction solar cell. For more accurate results and best configuration, the optical properties and the physical models such as the Fermi-Dirac statistics, Auger and Shockley-Read-Hall recombination, and the doping and temperature-dependent mobility model were taken into account in simulations. The single-junction In0.622Ga0.378N (Eg = 1.39 eV solar cell is the optimal structure found. It exhibits, under normalized conditions (AM1.5G, 0.1 W/cm2, and 300 K, the following electrical parameters: Jsc=32.6791 mA/cm2, Voc=0.94091 volts, FF = 86.2343%, and η=26.5056%. It was noticed that the minority carrier lifetime and the surface recombination velocity have an important effect on the solar cell performance. Furthermore, the investigation results show that the In0.622Ga0.378N solar cell efficiency was inversely proportional with the temperature.

  11. Amorphization of Ge and InP studied using nuclear hyperfine methods

    International Nuclear Information System (INIS)

    Byrne, A.P.; Bezakova, E.; Glover, C.J.; Ridgway, M.C.

    1999-01-01

    The ion beam amorphization of InP and Ge has been studied using the Perturbed Angular Correlation (PAC) technique. Semiconductor samples were preimplanted with the radioisotope 111 In using a direct production-recoil implantation method and beams from the ANU Heavy-ion Facility. Following annealing samples were amorphized using Ge beams with doses between 2 x 10 12 ion/cm 2 and 5000 x 10 12 ion/cm 2 . For InP the PAC spectra identified three distinct regimes, crystalline, disordered and amorphous environments, with a smooth transition observed as a function of dose. The dose dependence of the relative fractions of the individual probe environments has been determined. A direct amorphization process consistent with the overlap model was quantified and evidence for a second amorphization process via the overlap of disordered regions was observed. The PAC method compares favorably with other methods used in its ability to differentiate changes at high dose. The results for InP will be compared with those in Ge. The implantation method will be discussed, as will developments in the establishment of a dedicated facility for the implantation of radioisotopes

  12. Synthesis and characterization of metal oxide semiconductors by a facile co-electroplating-annealing method and formation of ZnO/CuO pn heterojunctions with rectifying behavior

    Science.gov (United States)

    Turkdogan, Sunay; Kilic, Bayram

    2018-01-01

    We have developed a unique growth method and demonstrated the growth of CuO and ZnO semiconductor materials and the fabrication of their pn heterojunctions in ambient atmosphere. The pn heterojunctions were constructed using inherently p-type CuO and inherently n-type ZnO materials. Both p- and n-type semiconductors and pn heterojunctions were prepared using a simple but versatile growth method that relies on the transformation of electroplated Cu and Zn metals into CuO and ZnO semiconductors, respectively and is capable of a large-scale production desired in most of the applications. The structural, chemical, optical and electrical properties of the materials and junctions were investigated using various characterization methods and the results show that our growth method, materials and devices are quite promising to be utilized for various applications including but not limited to solar cells, gas/humidity sensors and photodetectors.

  13. Ultra-Fast Low Energy Switching Using an InP Photonic Crystal H0 Nanocavity

    DEFF Research Database (Denmark)

    Yu, Yi; Palushani, Evarist; Heuck, Mikkel

    2013-01-01

    Pump-probe measurements on InP photonic crystal H0 nanocavities show large-contrast ultrafast switching at low pulse energy. For large pulse energies, high-frequency carrier density oscillations are induced, leading to pulsesplitting.......Pump-probe measurements on InP photonic crystal H0 nanocavities show large-contrast ultrafast switching at low pulse energy. For large pulse energies, high-frequency carrier density oscillations are induced, leading to pulsesplitting....

  14. The lower yield point of InP and GaAs

    International Nuclear Information System (INIS)

    Siethoff, H.

    1987-01-01

    A study of the strain-rate and temperature dependence of the lower yield stress (τ ly ) in undoped InP and of the strain-rate dependence of τ ly in undoped and Zn-doped GaAs is reported. The deformation along (123) orientation was carried out in compression at constant strain rates ranging from 10 -5 to 10 -2 s -1 . The temperature range extended from 540 to 780 0 C. The activation energy and stress exponent of the dislocation velocity were calculated. Experiments have shown that τ ly of InP depends on temperature and strain rate in a manner similar to other semiconductors like Si and InSb, whereas τ ly of GaAs shows an unusual strain-rate dependence

  15. [The Detection of Ultra-Broadband Terahertz Spectroscopy of InP Wafer by Using Coherent Heterodyne Time-Domain Spectrometer].

    Science.gov (United States)

    Zhang, Liang-liang; Zhang, Rui; Xu, Xiao-yan; Zhang, Cun-lin

    2016-02-01

    Indium Phosphide (InP) has attracted great physical interest because of its unique characteristics and is indispensable to both optical and electronic devices. However, the optical property of InP in the terahertz range (0. 110 THz) has not yet been fully characterized and systematically studied. The former researches about the properties of InP concentrated on the terahertz frequency between 0.1 and 4 THz. The terahertz optical properties of the InP in the range of 4-10 THz are still missing. It is fairly necessary to fully understand its properties in the entire terahertz range, which results in a better utilization as efficient terahertz devices. In this paper, we study the optical properties of undoped (100) InP wafer in the ultra-broad terahertz frequency range (0.5-18 THz) by using air-biased-coherent-detection (ABCD) system, enabling the coherent detection of terahertz wave in gases, which leads to a significant improvement on the dynamic range and sensitivity of the system. The advantage of this method is broad frequency bandwidth from 0.2 up to 18 THz which is only mainly limited by laser pulse duration since it uses ionized air as terahertz emitter and detector instead of using an electric optical crystal or photoconductive antenna. The terahertz pulse passing through the InP wafer is delayed regarding to the reference pulse and has much lower amplitude. In addition, the frequency spectrum amplitude of the terahertz sample signal drops to the noise floor level from 6.7 to 12.1 THz. At the same time InP wafer is opaque at the frequencies spanning from 6.7 to 12.1 THz. In the frequency regions of 0.8-6.7 and 12.1-18 THz it has relativemy low absorption coefficient. Meanwhile, the refractive index increases monotonously in the 0.8-6.7 THz region and 12.1-18 THz region. These findings will contribute to the design of InP based on nonlinear terahertz devices.

  16. Determination of the spin orbit coupling and crystal field splitting in wurtzite InP by polarization resolved photoluminescence

    Science.gov (United States)

    Chauvin, Nicolas; Mavel, Amaury; Jaffal, Ali; Patriarche, Gilles; Gendry, Michel

    2018-02-01

    Excitation photoluminescence spectroscopy is usually used to extract the crystal field splitting (ΔCR) and spin orbit coupling (ΔSO) parameters of wurtzite (Wz) InP nanowires (NWs). However, the equations expressing the valence band splitting are symmetric with respect to these two parameters, and a choice ΔCR > ΔSO or ΔCR InP NWs grown on silicon. The experimental results combined with a theoretical model and finite difference time domain calculations allow us to conclude that ΔCR > ΔSO in Wz InP.

  17. Enhanced EOS photovoltaic power system capability with InP solar cells

    Science.gov (United States)

    Bailey, Sheila G.; Weinberg, Irving; Flood, Dennis J.

    1991-01-01

    The Earth Observing System (EOS), which is part of the International Mission to Planet Earth, is NASA's main contribution to the Global Change Research Program which opens a new era in international cooperation to study the Earth's environment. Five large platforms are to be launched into polar orbit, two by NASA, two by ESA, and one by the Japanese. In such an orbit the radiation resistance of indium phosphide solar cells combined with the potential of utilizing five micron cell structures yields an increase of 10 percent in the payload capability. If further combined with the advanced photovoltaic solar array the payload savings approaches 12 percent.

  18. 1990's annual report of INPE's Plasma Associated Laboratory

    International Nuclear Information System (INIS)

    1991-06-01

    This is the 1990's annual report of INPE's Plasma Associated Laboratory it contains information on current research developed at the laboratory including quiescent plasma, magnetized plasma, plasma centrifuge, plasma and radiation (gyrotron), ionic propulsion, and toroidal plasma. (A.C.A.S.)

  19. Technetium-99m labeling of N-[N-(3-diphenylphosphino propionyl)glycyl]cysteine (PN2S-OH) and its methyl ester derivative (PN2S-OMe)

    International Nuclear Information System (INIS)

    Visentin, Roberta; Giron, Maria Cecilia; Bello, Michele; Mazzi, Ulderico

    2004-01-01

    N-[N-(3-diphenylphosphinopropionyl)glycyl]cysteine and its methyl ester derivative were labeled with 99m Tc at neutral pH, leading to a single species in high yield (>95%) in 30 min. RP-HPLC comparison with the analogue Re V -oxo complexes identified the labeled compounds as the anti isomers of pentacoordinated 99m TcO[PN 2 S]-OH and 99m TcO[PN 2 S]-OMe complexes. The compounds are stable from pH 7 to pH 9 when 99m TcO[PN 2 S]-OH interconverts to related syn isomer, while 99m TcO[PN 2 S]-OMe undergoes both saponification and interconversion. They exhibit high stability in human plasma and in vivo (mice), and a biodistribution characterized by hepatobiliary excretion

  20. Pressure-Dependent Photoluminescence Study of Wurtzite InP Nanowires.

    Science.gov (United States)

    Chauvin, Nicolas; Mavel, Amaury; Patriarche, Gilles; Masenelli, Bruno; Gendry, Michel; Machon, Denis

    2016-05-11

    The elastic properties of InP nanowires are investigated by photoluminescence measurements under hydrostatic pressure at room temperature and experimentally deduced values of the linear pressure coefficients are obtained. The pressure-induced energy shift of the A and B transitions yields a linear pressure coefficient of αA = 88.2 ± 0.5 meV/GPa and αB = 89.3 ± 0.5 meV/GPa with a small sublinear term of βA = βB = -2.7 ± 0.2 meV/GPa(2). Effective hydrostatic deformation potentials of -6.12 ± 0.04 and -6.2 ± 0.04 eV are derived from the results for the A and B transitions, respectively. A decrease of the integrated intensity is observed above 0.5 GPa and is interpreted as a carrier transfer from the first to the second conduction band of the wurtzite InP.

  1. Effects of nitrogen incorporation in HfO(2) grown on InP by atomic layer deposition: an evolution in structural, chemical, and electrical characteristics.

    Science.gov (United States)

    Kang, Yu-Seon; Kim, Dae-Kyoung; Kang, Hang-Kyu; Jeong, Kwang-Sik; Cho, Mann-Ho; Ko, Dae-Hong; Kim, Hyoungsub; Seo, Jung-Hye; Kim, Dong-Chan

    2014-03-26

    We investigated the effects of postnitridation on the structural characteristics and interfacial reactions of HfO2 thin films grown on InP by atomic layer deposition (ALD) as a function of film thickness. By postdeposition annealing under NH3 vapor (PDN) at 600 °C, an InN layer formed at the HfO2/InP interface, and ionized NHx was incorporated in the HfO2 film. We demonstrate that structural changes resulting from nitridation of HfO2/InP depend on the film thickness (i.e., a single-crystal interfacial layer of h-InN formed at thin (2 nm) HfO2/InP interfaces, whereas an amorphous InN layer formed at thick (>6 nm) HfO2/InP interfaces). Consequently, the tetragonal structure of HfO2 transformed into a mixture structure of tetragonal and monoclinic because the interfacial InN layer relieved interfacial strain between HfO2 and InP. During postdeposition annealing (PDA) in HfO2/InP at 600 °C, large numbers of oxidation states were generated as a result of interfacial reactions between interdiffused oxygen impurities and out-diffused InP substrate elements. However, in the case of the PDN of HfO2/InP structures at 600 °C, nitrogen incorporation in the HfO2 film effectively blocked the out-diffusion of atomic In and P, thus suppressing the formation of oxidation states. Accordingly, the number of interfacial defect states (Dit) within the band gap of InP was significantly reduced, which was also supported by DFT calculations. Interfacial InN in HfO2/InP increased the electron-barrier height to ∼0.6 eV, which led to low-leakage-current density in the gate voltage region over 2 V.

  2. The Outcome for Patients With Pathologic Node-Positive Prostate Cancer Treated With Intensity Modulated Radiation Therapy and Androgen Deprivation Therapy: A Case-Matched Analysis of pN1 and pN0 Patients

    International Nuclear Information System (INIS)

    Van Hemelryk, Annelies; De Meerleer, Gert; Ost, Piet; Poelaert, Filip; De Gersem, Werner; Decaestecker, Karel; De Visschere, Pieter; Fonteyne, Valérie

    2016-01-01

    Purpose: Improved outcome is reported after surgery or external beam radiation therapy (EBRT) plus androgen deprivation therapy (ADT) for patients with lymph node (LN) positive (N1) prostate cancer (PC). Surgical series have shown that pathologic (p)N1 PC does not behave the same in all patients. The aim of this study was to perform a matched-case analysis to compare the outcome of pN1 and pN0 PC after high-dose EBRT plus ADT. Methods and Materials: Radiation therapy up to 80 Gy was delivered to the prostate with a minimal dose of 45 Gy to the pelvis for pN1 patients. After matching, Kaplan-Meier statistics were used to compare the 5-year biochemical and clinical relapse-free survival (bRFS and cRFS), prostate cancer–specific survival (PCSS), and overall survival (OS). Acute and late rectal and urinary toxicity was evaluated. Results: Sixty-nine pN1 PC patients were matched 1:1 with pN0 PC patients. The median follow-up time was 60 months. The 5-year bRFS and cRFS for pN1 versus pN0 PC patients were 65% ± 7% versus 79% ± 5% (P=.08) and 70% ± 6% versus 83% ± 5% (P=.04) respectively. No significant difference was found in bRFS or cRFS rates between low volume pN1 (≤2 positive LNs) and pN0 patients. The 5-year PCSS and OS were comparable between pN1 and pN0 PC patients: PCSS: 92% ± 4% versus 93% ± 3% (P=.66); OS: 82% ± 5% versus 80% ± 5% (P=.58). Severe toxicity was rare for both groups, although pN1 patients experienced significantly more acute grade 2 rectal toxicity. Conclusion: Primary EBRT plus 2 to 3 years of ADT is a legitimate treatment option for pN1 PC patients, especially those with ≤2 positive LNs, and this with bRFS and cRFS rates comparable to those in pN0 PC patients. For pN1 PC patients with >2 positive LNs, bRFS and cRFS are worse than in pN0 patients, but even in this subgroup, long-term disease control is obtained.

  3. The Outcome for Patients With Pathologic Node-Positive Prostate Cancer Treated With Intensity Modulated Radiation Therapy and Androgen Deprivation Therapy: A Case-Matched Analysis of pN1 and pN0 Patients

    Energy Technology Data Exchange (ETDEWEB)

    Van Hemelryk, Annelies [Department of Urology, Ghent University Hospital, Ghent (Belgium); De Meerleer, Gert; Ost, Piet [Department of Radiation Oncology, Ghent University Hospital, Ghent (Belgium); Poelaert, Filip [Department of Urology, Ghent University Hospital, Ghent (Belgium); De Gersem, Werner [Department of Radiation Oncology, Ghent University Hospital, Ghent (Belgium); Decaestecker, Karel [Department of Urology, Ghent University Hospital, Ghent (Belgium); De Visschere, Pieter [Department of Radiology, Ghent University Hospital, Ghent (Belgium); Fonteyne, Valérie, E-mail: valerie.fonteyne@uzgent.be [Department of Radiation Oncology, Ghent University Hospital, Ghent (Belgium)

    2016-10-01

    Purpose: Improved outcome is reported after surgery or external beam radiation therapy (EBRT) plus androgen deprivation therapy (ADT) for patients with lymph node (LN) positive (N1) prostate cancer (PC). Surgical series have shown that pathologic (p)N1 PC does not behave the same in all patients. The aim of this study was to perform a matched-case analysis to compare the outcome of pN1 and pN0 PC after high-dose EBRT plus ADT. Methods and Materials: Radiation therapy up to 80 Gy was delivered to the prostate with a minimal dose of 45 Gy to the pelvis for pN1 patients. After matching, Kaplan-Meier statistics were used to compare the 5-year biochemical and clinical relapse-free survival (bRFS and cRFS), prostate cancer–specific survival (PCSS), and overall survival (OS). Acute and late rectal and urinary toxicity was evaluated. Results: Sixty-nine pN1 PC patients were matched 1:1 with pN0 PC patients. The median follow-up time was 60 months. The 5-year bRFS and cRFS for pN1 versus pN0 PC patients were 65% ± 7% versus 79% ± 5% (P=.08) and 70% ± 6% versus 83% ± 5% (P=.04) respectively. No significant difference was found in bRFS or cRFS rates between low volume pN1 (≤2 positive LNs) and pN0 patients. The 5-year PCSS and OS were comparable between pN1 and pN0 PC patients: PCSS: 92% ± 4% versus 93% ± 3% (P=.66); OS: 82% ± 5% versus 80% ± 5% (P=.58). Severe toxicity was rare for both groups, although pN1 patients experienced significantly more acute grade 2 rectal toxicity. Conclusion: Primary EBRT plus 2 to 3 years of ADT is a legitimate treatment option for pN1 PC patients, especially those with ≤2 positive LNs, and this with bRFS and cRFS rates comparable to those in pN0 PC patients. For pN1 PC patients with >2 positive LNs, bRFS and cRFS are worse than in pN0 patients, but even in this subgroup, long-term disease control is obtained.

  4. Structural and thermoelectric properties of zintl-phase CaLiPn (Pn=As, Sb, Bi)

    Energy Technology Data Exchange (ETDEWEB)

    Chandran, Anoop K.; Gudelli, Vijay Kumar; Sreeparvathy, P.C.; Kanchana, V., E-mail: kanchana@iith.ac.in

    2016-11-15

    First-principles calculations were carried out to study the structural, mechanical, dynamical and transport properties of zintl phase materials CaLiPn (Pn=As, Sb and Bi). We have used two different approaches to solve the system based on density functional theory. The plane wave pseudopotential approach has been used to study the structural and dynamical properties whereas, full potential linear augment plane wave method is used to examine the electronic structure, mechanical and thermoelectric properties. The calculated ground-state properties agree quite well with experimental values. The computed electronic structure shows the investigated compounds to be direct band gap semiconductors. Further, we have calculated the thermoelectric properties of all the investigated compounds for both the carriers at various temperatures. We found a high thermopower for both the carriers, especially n-type doping to be more favourable, which enabled us to predict that CaLiPn might have promising applications as a good thermoelectric material. Further, the phonon dispersion curves of the investigated compounds showed flat phonon modes and we also find lower optical and acoustic modes to cut each other at the lower frequency range, which further indicate the investigated compounds to possess reasonably low thermal conductivity. We have also analysed the low value of the thermal conductivity through the empirical relations and discussions are presented here. - Highlights: • Electronic band structure and chemical bonding. • Single crystalline elastic constants and poly crystalline elastic moduli. • Thermoelectric properties of zintl phase. • Lattice dynamics and phonon density of states.

  5. Impacto da utilização de previsões "defasadas" no sistema de previsão de tempo por conjunto do CPTEC/INPE The impact of using lagged forecasts on the CPTEC/INPE ensemble prediction system

    Directory of Open Access Journals (Sweden)

    Lúcia Helena Ribas Machado

    2010-03-01

    Full Text Available Neste trabalho é descrita a aplicação da técnica de previsões defasadas no sistema de previsão de tempo por conjuntos do Centro de Previsão de Tempo e Estudos Climáticos (EPS-CPTEC/INPE. Os dados do CPTEC/INPE consistem em uma amostra de dois meses com previsões de 15 dias para as variáveis: altura geopotencial em 500 hPa, temperatura do ar no nível de 850 hPa, e pressão atmosférica ao nível médio do mar. O estudo consiste em investigar: 1 o desempenho do EPS-CPTEC/INPE utilizando a técnica de previsões defasadas comparado àquele do conjunto operacional; 2 a relação entre o espalhamento e o desempenho da previsão, a fim de avaliar o uso da dispersão como preditor do desempenho. Os resultados indicam que a utilização de previsões defasadas em 12h, melhora o desempenho do conjunto operacional, contribuindo para aumentar o espalhamento do conjunto e, conseqüentemente, reduzir a sub-dispersão do sistema. Também foi observado que o conjunto defasado tem desempenho comparável àquele do conjunto operacional e que há uma tendência de desempenho alto quando o espalhamento é baixo, para os prazos de 5 e 7 dias de previsão. Estes resultados servem como base para a implementação operacional desta técnica, que apresenta baixo custo computacional, e contribui para a utilização mais eficiente das previsões por conjunto do CPTEC/INPE.In this work we report the application of the lagged average forecasting technique to CPTEC/INPE ensemble forecast. The CPTEC/INPE data consist of two months samples of 15 days forecast for the variables: geopotential height at 500 hPa, air temperature at 850 hPa and mean sea level atmospheric pressure. We focus on the following: 1 Does the lagged averaged ensemble forecast improve forecast skill compared to the CPTEC/INPE operational ensemble? 2 Is the dispersion of the ensemble useful in predicting forecast skill? The results indicate that the utilization of 12h-lagged average forecasts

  6. Controllable growth and optical properties of InP and InP/InAs nanostructures on the sidewalls of GaAs nanowires

    International Nuclear Information System (INIS)

    Yan, Xin; Zhang, Xia; Li, Junshuai; Cui, Jiangong; Ren, Xiaomin

    2014-01-01

    The growth and optical properties of InP and InP/InAs nanostructures on GaAs nanowires are investigated. InP quantum well and quantum dots (QDs) are formed on the sidewalls of GaAs nanowires successively with increasing the deposition time of InP. The GaAs/InP nanowire heterostructure exhibits a type-II band alignment. The wavelength of the InP quantum well is in the range of 857–892 nm at 77 K, which means that the quantum well is nearly fully strained. The InP quantum dot, which has a bow-shaped cross section, exhibits dislocation-free pure zinc blende structure. Stranski-Krastanow InAs quantum dots are subsequently formed on the GaAs/InP nanowire core-shell structure. The InAs quantum dots are distributed over the middle part of the nanowire, indicating that the In atoms contributing to the quantum dots mainly come from the vapor rather than the substrate. The longest emission wavelength obtained from the InAs QDs is 1039 nm at 77 K. The linewidth is as narrow as 46.3 meV, which is much narrower than those on planar InP substrates and wurtzite InP nanowires, suggesting high-crystal-quality, phase-purity, and size-uniformity of quantum dots

  7. The electrochemistry of InP in Br2/HBr solutions and its relevance to etching behaviour

    NARCIS (Netherlands)

    Notten, P.H.L.; Damen, A.A.J.M.

    1987-01-01

    Etch rate-potential curves of p-InP in HBr and Br2/HBr solutions in the dark and under illumination were correlated with current-potential curves. It was found that InP is etched via a "chemical" mechanism both by HBr and Br2. In aqueous HBr solutions InP is only etched at a significant rate at

  8. Semiclassical Monte Carlo simulation studies of spin dephasing in InP and InSb nanowires

    Directory of Open Access Journals (Sweden)

    Ashish Kumar

    2012-03-01

    Full Text Available We use semiclassical Monte Carlo approach to investigate spin polarized transport in InP and InSb nanowires. D’yakonov-Perel (DP relaxation and Elliott-Yafet (EY relaxation are the two main relaxation mechanisms for spin dephasing in III-V channels. The DP relaxation occurs because of bulk inversion asymmetry (Dresselhaus spin-orbit interaction and structural inversion asymmetry (Rashba spin-orbit interaction. The injection polarization direction studied is that along the length of the channel. The dephasing rate is found to be very strong for InSb as compared to InP which has larger spin dephasing lengths. The ensemble averaged spin components vary differently for both InP and InSb nanowires. The steady state spin distribution also shows a difference between the two III-V nanowires.

  9. Particle detectors based on InP Schottky diodes

    Czech Academy of Sciences Publication Activity Database

    Yatskiv, Roman; Grym, Jan

    2012-01-01

    Roč. 10, č. 7 (2012), C100051-C100055 ISSN 1748-0221 R&D Projects: GA MŠk(CZ) OC10021; GA MŠk LD12014 Institutional support: RVO:67985882 Keywords : Particle detector * High purity InP layer * Schottky diode Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering Impact factor: 1.869, year: 2011

  10. Photoelectrochemistry of III-V epitaxial layers and nanowires for solar energy conversion

    Science.gov (United States)

    Parameshwaran, Vijay; Enck, Ryan; Chung, Roy; Kelley, Stephen; Sampath, Anand; Reed, Meredith; Xu, Xiaoqing; Clemens, Bruce

    2017-05-01

    III-V materials, which exhibit high absorption coefficients and charge carrier mobility, are ideal templates for solar energy conversion applications. This work describes the photoelectrochemistry research in several IIIV/electrolyte junctions as an enabler for device design for solar chemical reactions. By designing lattice-matched epitaxial growth of InGaP and GaP on GaAs and Si, respectively, extended depletion region electrodes achieve photovoltages which provide an additional boost to the underlying substrate photovoltage. The InGaP/GaAs and GaP/Si electrodes drive hydrogen evolution currents under aqueous conditions. By using nanowires of InN and InP under carefully controlled growth conditions, current and capacitance measurements are obtained to reveal the nature of the nanowire-electrolyte interface and how light is translated into photocurrent for InP and a photovoltage in InN. The materials system is expanded into the III-V nitride semiconductors, in which it is shown that varying the morphology of GaN on silicon yields insights to how the interface and light conversion is modulated as a basis for future designs. Current extensions of this work address growth and tuning of the III-V nitride electrodes with doping and polarization engineering for efficient coupling to solar-driven chemical reactions, and rapid-throughput methods for III-V nanomaterials synthesis in this materials space.

  11. Design of mm-wave InP DHBT power amplifiers

    DEFF Research Database (Denmark)

    Johansen, Tom Keinicke; Yan, Lei

    2011-01-01

    In this paper suitable topologies for mm-wave integrated power amplifiers using InP DHBT technology is investigated. Among the standard topologies for mm-wave power cells: common-emitter, common-base, and cascode configuration, the cascode configuration proves the most promising in terms of output...

  12. Phosphorus-hydrogen complexes in LEC-grown InP

    International Nuclear Information System (INIS)

    Ulrici, W.; Kwasniewski, A.; Czupalla, M.; Neubert, M.

    2005-01-01

    In LEC-grown InP, about 30 sharp vibrational absorption lines are measured in the frequency region 2200 to 2350 cm -1 . All these lines are due to phosphorus-hydrogen stretching modes. Experiments on InP containing both hydrogen and deuterium finally proved that the line at 2202.4 cm -1 is due to a single hydrogen atom bonded to P in an indium vacancy (V In ) and that the line at 2315.6 cm -1 is due to the complex of four P-H bonds in an V In . In InP:H:D, this V In H 4 complex gives rise to six vibrational lines in the region of P-H modes and six lines in the region of P-D modes because of the five different types of V In H n D m complexes. The measured frequencies of these 12 lines are in excellent agreement with those obtained from ab initio calculations reported in the literature. Additional P-H complexes are discussed. (copyright 2005 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  13. Modeling of High-Speed InP DHBTs using Electromagnetic Simulation Based De-embedding

    DEFF Research Database (Denmark)

    Johansen, Tom Keinicke; Krozer, Viktor; Konczykowska, Agnieszka

    2006-01-01

    In this paper an approach for high-speed InP DHBT modeling valid to 110 GHz is reported. Electromagnetic (EM) simulation is applied to predict the embedded network model caused by pad parasitics. The form of the parasitic network calls for a 4-step de-embedding approach. Applying direct parameter...... extraction on the de-embedded device response leads to accurate small-signal model description of the InP DHBT. An parameter extraction approach is described for the Agilent HBT model, which assures consistency between large-signal and bias-dependent smallsignal modeling....

  14. (p,n) reaction at intermediate energy

    International Nuclear Information System (INIS)

    Goodman, C.D.

    1979-01-01

    The use of the (p,n) reaction in exploring effective interactions is reviewed. Some recent data on self-conjugate nuclei taken at the Indiana University Cyclotron Facility (IUCF) are presented, and the differences between low- and high-energy data are emphasized. Experimental problems and techniques used are briefly described. It is concluded that forward-angle (p,n) spectra at energies greater than 100 MeV are dominated by Gamow-Teller (GT) transitions, while Fermi transitions (IAS transitions) dominate near 45 MeV. Prominent GT transitions are expected from a pion-exchange interaction, and it is expected that OPEP is the dominant component of the interaction in the energy range of 100 to 200 MeV. 27 figures, 2 tables

  15. Minimum entropy principle-based solar cell operation without a pn-junction and a thin CdS layer to extract the holes from the emitter

    Science.gov (United States)

    Böer, Karl W.

    2016-10-01

    The solar cell does not use a pn-junction to separate electrons from holes, but uses an undoped CdS layer that is p-type inverted when attached to a p-type collector and collects the holes while rejecting the backflow of electrons and thereby prevents junction leakage. The operation of the solar cell is determined by the minimum entropy principle of the cell and its external circuit that determines the electrochemical potential, i.e., the Fermi-level of the base electrode to the operating (maximum power point) voltage. It leaves the Fermi level of the metal electrode of the CdS unchanged, since CdS does not participate in the photo-emf. All photoelectric actions are generated by the holes excited from the light that causes the shift of the quasi-Fermi levels in the generator and supports the diffusion current in operating conditions. It is responsible for the measured solar maximum power current. The open circuit voltage (Voc) can approach its theoretical limit of the band gap of the collector at 0 K and the cell increases the efficiency at AM1 to 21% for a thin-film CdS/CdTe that is given as an example here. However, a series resistance of the CdS forces a limitation of its thickness to preferably below 200 Å to avoid unnecessary reduction in efficiency or Voc. The operation of the CdS solar cell does not involve heated carriers. It is initiated by the field at the CdS/CdTe interface that exceeds 20 kV/cm that is sufficient to cause extraction of holes by the CdS that is inverted to become p-type. Here a strong doubly charged intrinsic donor can cause a negative differential conductivity that switches-on a high-field domain that is stabilized by the minimum entropy principle and permits an efficient transport of the holes from the CdTe to the base electrode. Experimental results of the band model of CdS/CdTe solar cells are given and show that the conduction bands are connected in the dark, where the electron current must be continuous, and the valence bands are

  16. Terahertz-radiation generation in low-temperature InGaAs epitaxial films on (100) and (411) InP substrates

    Energy Technology Data Exchange (ETDEWEB)

    Galiev, G. B., E-mail: galiev-galib@mail.ru [Russian Academy of Sciences, Institute of Ultra-High Frequency Semiconductor Electronics (Russian Federation); Grekhov, M. M. [National Research Nuclear University “MEPhI” (Russian Federation); Kitaeva, G. Kh. [Moscow State University, Faculty of Physics (Russian Federation); Klimov, E. A.; Klochkov, A. N. [Russian Academy of Sciences, Institute of Ultra-High Frequency Semiconductor Electronics (Russian Federation); Kolentsova, O. S. [National Research Nuclear University “MEPhI” (Russian Federation); Kornienko, V. V.; Kuznetsov, K. A. [Moscow State University, Faculty of Physics (Russian Federation); Maltsev, P. P.; Pushkarev, S. S. [Russian Academy of Sciences, Institute of Ultra-High Frequency Semiconductor Electronics (Russian Federation)

    2017-03-15

    The spectrum and waveforms of broadband terahertz-radiation pulses generated by low-temperature In{sub 0.53}Ga{sub 0.47}As epitaxial films under femtosecond laser pumping are investigated by terahertz time-resolved spectroscopy. The In{sub 0.53}Ga{sub 0.47}As films are fabricated by molecular-beam epitaxy at a temperature of 200°C under different arsenic pressures on (100)-oriented InP substrates and, for the first time, on (411)A InP substrates. The surface morphology of the samples is studied by atomic-force microscopy and the structural quality is established by high-resolution X-ray diffraction analysis. It is found that the amplitude of terahertz radiation from the LT-InGaAs layers on the (411)A InP substrates exceeds that from similar layers formed on the (100) InP substrates by a factor of 3–5.

  17. P-N junction solar cell grown by molecular beam epitaxy

    International Nuclear Information System (INIS)

    Hazrati Fard, M.

    2001-01-01

    Growth of GaAs epilayers by Molecular Beam Epitaxy was accomplished for the first time in Iran. The layers were grown on GaAs (001) substrates (p+ wafer) with Si impurity for p n junction solar cell fabrication at a rate of nearly one micron per hour and 0.25 micron per quarter. Crystalline quality of grown layers had been monitored during growth by Reflection High Energy Electron Diffraction system. Doping profile and layer thickness was assessed by electrochemical C-V profiling method. Then Hall measurements were conducted on small samples both in room temperature and liquid nitrogen temperature so giving average carrier concentration and compensation ratio. The results as like: V oc , I sc , F F, η were comparable with other laboratory reports. information for obtaining good and repeatable growths was collected. Therefore, the conditions of repeatable quality growth p n junction solar cells onto GaAs (001) substrates were determined

  18. Optical reflectance studies of highly specular anisotropic nanoporous (111) InP membrane

    International Nuclear Information System (INIS)

    Steele, J A; Lewis, R A; Sirbu, L; Enachi, M; Tiginyanu, I M; Skuratov, V A

    2015-01-01

    High-precision optical angular reflectance measurements are reported for a specular anisotropic nanoporous (111) InP membrane prepared by doping-assisted wet-electrochemical etching. The membrane surface morphology was investigated using scanning electron microscope imaging and revealed a quasi-uniform and self-organized nanoporous network consisting of semiconductor ‘islands’ in the sub-wavelength regime. The optical response of the nanoporous InP surface was studied at 405 nm (740 THz; UV), 633 nm (474 THz; VIS) and 1064 nm (282 THz; NIR), and exhibited a retention of basic macro-dielectric properties. Refractive index determinations demonstrate an optical anisotropy for the membrane which is strongly dependent on the wavelength of incident light, and exhibits an interesting inversion (positive anisotropy to negative) between 405 and 633 nm. The inversion of optical anisotropy is attributed to a strongly reduced ‘metallic’ behaviour in the membrane when subject to above-bandgap illumination. For the simplest case of sub-bandgap incident irradiation, the optical properties of the nanoporous InP sample are analysed in terms of an effective refractive index n eff and compared to effective media approximations. (invited article)

  19. InP DHBT MMICs for millimeter-wave front-ends

    DEFF Research Database (Denmark)

    Johansen, Tom Keinicke; Hadziabdic, Dzenan; Krozer, Viktor

    2009-01-01

    In this paper, we show advanced MMIC's using InP DHBT technology. In particular, we demonstrate front-end circuits covering a broad frequency range from Q-band to E-band. Realizations of power amplifiers, quadrature VCOs, and sub-harmonic mixers, are presented and experimental results are discussed....

  20. Method of making quasi-grain boundary-free polycrystalline solar cell structure and solar cell structure obtained thereby

    Science.gov (United States)

    Gonzalez, Franklin N.; Neugroschel, Arnost

    1984-02-14

    A new solar cell structure is provided which will increase the efficiency of polycrystalline solar cells by suppressing or completely eliminating the recombination losses due to the presence of grain boundaries. This is achieved by avoiding the formation of the p-n junction (or other types of junctions) in the grain boundaries and by eliminating the grain boundaries from the active area of the cell. This basic concept can be applied to any polycrystalline material; however, it will be most beneficial for cost-effective materials having small grains, including thin film materials.

  1. X-ray photoelectron spectroscopy/Ar+ ion profile study of thin oxide layers on InP

    International Nuclear Information System (INIS)

    Thurgate, S.M.; Erickson, N.E.

    1990-01-01

    The effect of incremental ion bombardment on the surface layers of an aqua regia etched InP sample was studied by monitoring the components of the In 3d 5/2 and O 1s x-ray photoelectron spectroscopy (XPS) lines as the sample was bombarded with low energy (1 keV) Ar + ions. The changes in the stoichiometry of the surface produced large shifts in the position of the In 3d and O 1s lines that were not paralleled by shifts in the P 2p line. Analysis of these shifts indicated that the surface was covered with a mixture of indium hydroxide and indium phosphate, with the phosphate closer to the InP substrate. It is proposed that this layer structure is due to differences in the dissolution rates of the oxidation products in the acid etch and the effect of the distilled water rinse. It may be possible to alter the composition of such oxides by carefully tailoring the etch conditions to optimize the kinetics for the particular oxide phase required. The analysis of the XPS lines also showed that the InP substrate was damaged at very low ion doses, and finally decomposed by the ion beam. When the ion ''cleaned'' sample was exposed to oxygen, a different oxide system was produced which consisted largely of In 2 O 3 and InPO 4 [or In(PO 3 ) x ]. This model of the oxidized surface of InP is consistent with other measurements and we conclude that ion milling together with XPS and careful curve fitting can be used to find the nature of the thin oxides on InP

  2. Photoreflection investigations of the dopant activation in InP doped with beryllium ions

    International Nuclear Information System (INIS)

    Avakyants, L.P.; Bokov, P.Yu.; Chervyakov, A.V.

    2005-01-01

    The processes of the dopant activation in the InP crystals implanted with Be + ions (energy 100 keV, dose 10 13 cm -2 and subsequent thermal annealing during 10 s) have been studied by means of photoreflection spectroscopy. Spectral lines of the crystal InP were absent in the photoreflection spectra of the samples annealed at temperatures less then 400 Deg C. This fact is connected with the disordering of the crystal structure due to the ion implantation. In the temperature range 400-700 Deg C the lines from InP band gap (1.34 eV) and conductance band-spin-orbit splitting valence subband (1.44 eV) have been observed due to the recovery of the crystal structure. In the photoreflectance spectra of a 800 Deg C annealed sample the Franz-Keldysh oscillations have been observed, which can be an evidence in favour of the dopant activation. Carrier concentration calculated from the period of Franz-Keldysh oscillations was equal to 2.2 x 10 16 cm -3 [ru

  3. Thermal conductivity of InAs quantum dot stacks using AlAs strain compensating layers on InP substrate

    International Nuclear Information System (INIS)

    Salman, S.; Folliot, H.; Le Pouliquen, J.; Chevalier, N.; Rohel, T.; Paranthoën, C.; Bertru, N.; Labbé, C.; Letoublon, A.; Le Corre, A.

    2012-01-01

    Highlights: ► The thermal conductivity of InAs on InP (1 1 3)B quantum dots stacks is measured. ► The growth of a close stack of 100 layers of InAs using AlAs strain compensating layers is presented. ► New data on the thermal conductivity of InP n-doped susbtrate are given. - Abstract: The growth and thermal conductivity of InAs quantum dot (QD) stacks embedded in GaInAs matrix with AlAs compensating layers deposited on (1 1 3)B InP substrate are presented. The effect of the strain compensating AlAs layer is demonstrated through Atomic Force Microscopy (AFM) and X-ray diffraction structural analysis. The thermal conductivity (2.7 W/m K at 300 K) measured by the 3ω method reveals to be clearly reduced in comparison with a bulk InGaAs layer (5 W/m K). In addition, the thermal conductivity measurements of S doped InP substrates and the SiN insulating layer used in the 3ω method in the 20–200 °C range are also presented. An empirical law is proposed for the S doped InP substrate, which slightly differs from previously presented results.

  4. Effects of Be doping on InP nanowire growth mechanisms

    Energy Technology Data Exchange (ETDEWEB)

    Yee, R. J.; Gibson, S. J.; LaPierre, R. R. [Department of Engineering Physics, Centre for Emerging Device Technologies, McMaster University, Hamilton, Ontario L8S 4L7 (Canada); Dubrovskii, V. G. [St. Petersburg Academic University, Khlopina 8/3, 194021 St. Petersburg (Russian Federation); Ioffe Physical Technical Institute RAS, Politekhnicheskaya 26, 194021 St. Petersburg (Russian Federation)

    2012-12-24

    Be-doped InP nanowires were grown by the gold-assisted vapour-liquid-solid mechanism in a gas source molecular beam epitaxy system. The InP nanowire length versus diameter [L(D)] dependence revealed an unexpected transition with increasing Be dopant concentration. At Be dopant concentration below {approx}10{sup 18} cm{sup -3}, nanowires exhibited the usual inverse L(D) relationship, indicating a diffusion-limited growth regime. However, as dopant concentration increased, the nanowire growth rate was suppressed for small diameters, resulting in an unusual L(D) dependence that increased before saturating in height at about 400 nm. The cause of this may be a change in the droplet chemical potential, introducing a barrier to island nucleation. We propose a model accounting for the limitations of diffusion length and monolayer nucleation to explain this behaviour.

  5. Bootstrap inversion for Pn wave velocity in North-Western Italy

    Directory of Open Access Journals (Sweden)

    C. Eva

    1997-06-01

    Full Text Available An inversion of Pn arrival times from regional distance earthquakes (180-800 km, recorded by 94 seismic stations operating in North-Western Italy and surrounding areas, was carried out to image lateral variations of P-wave velocity at the crust-mantle boundary, and to estimate the static delay time at each station. The reliability of the obtained results was assessed using both synthetic tests and the bootstrap Monte Carlo resampling technique. Numerical simulations demonstrated the existence of a trade-off between cell velocities and estimated station delay times along the edge of the model. Bootstrap inversions were carried out to determine the standard deviation of velocities and time terms. Low Pn velocity anomalies are detected beneath the outer side of the Alps (-6% and the Western Po plain (-4% in correspondence with two regions of strong crustal thickening and negative Bouguer anomaly. In contrast, high Pn velocities are imaged beneath the inner side of the Alps (+4% indicating the presence of high velocity and density lower crust-upper mantle. The Ligurian sea shows high Pn velocities close to the Ligurian coastlines (+3% and low Pn velocities (-1.5% in the middle of the basin in agreement with the upper mantle velocity structure revealed by seismic refraction profiles.

  6. Electroplated Ni on the PN Junction Semiconductor

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jin Joo; Uhm, Young Rang; Son, Kwang Jae; Kim, Jong Bum; Choi, Sang Moo; Park, Jong Han; Hong, Jintae [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2015-05-15

    Nickel (Ni) electroplating was implemented by using a metal Ni powder in order to establish a Ni-63 plating condition on the PN junction semiconductor needed for production of betavoltaic battery. PN junction semiconductors with a Ni seed layer of 500 and 1000 A were coated with Ni at current density from 10 to 50 mA cm{sup 2}. The surface roughness and average grain size of Ni deposits were investigated by XRD and SEM techniques. The roughness of Ni deposit was increased as the current density was increased, and decreased as the thickness of Ni seed layer was increased.

  7. Electroplated Ni on the PN Junction Semiconductor

    International Nuclear Information System (INIS)

    Kim, Jin Joo; Uhm, Young Rang; Son, Kwang Jae; Kim, Jong Bum; Choi, Sang Moo; Park, Jong Han; Hong, Jintae

    2015-01-01

    Nickel (Ni) electroplating was implemented by using a metal Ni powder in order to establish a Ni-63 plating condition on the PN junction semiconductor needed for production of betavoltaic battery. PN junction semiconductors with a Ni seed layer of 500 and 1000 A were coated with Ni at current density from 10 to 50 mA cm 2 . The surface roughness and average grain size of Ni deposits were investigated by XRD and SEM techniques. The roughness of Ni deposit was increased as the current density was increased, and decreased as the thickness of Ni seed layer was increased

  8. Ionospheric research at INPE

    International Nuclear Information System (INIS)

    Abdu, M.A.

    1984-01-01

    Ionosphere investigations at INPE are mainly concerned with the problems of equatorial and tropical ionospheres and their electrodynamic coupling with the high latitude ionosphere. Present research objectives include investigations in the following specific areas: equatorial ionospheric plasma dynamics; plasma irregularity generation and morphology, and effects on space borne radar operations; ionospheric response to disturbance dynamo and magnetospheric electric fields; aeronomic effcts of charged particle precipitation in the magnetic anomaly, etc. These problems are being investigated using experimental datacollected from ionospheric diagnostic instruments being operated at different locations in Brazil. These instruments are: ionosondes, VHF electronic polarimeters, L-band scintillation receivers, airglow photometers, riometers and VLF receivers. A brief summary of the research activities and some recnet results will be presented. (Author) [pt

  9. Facile synthesis of uniform large-sized InP nanocrystal quantum dots using tris(tert-butyldimethylsilyl)phosphine

    Science.gov (United States)

    2012-01-01

    Colloidal III-V semiconductor nanocrystal quantum dots [NQDs] have attracted interest because they have reduced toxicity compared with II-VI compounds. However, the study and application of III-V semiconductor nanocrystals are limited by difficulties in their synthesis. In particular, it is difficult to control nucleation because the molecular bonds in III-V semiconductors are highly covalent. A synthetic approach of InP NQDs was presented using newly synthesized organometallic phosphorus [P] precursors with different functional moieties while preserving the P-Si bond. Introducing bulky side chains in our study improved the stability while facilitating InP formation with strong confinement at a readily low temperature regime (210°C to 300°C). Further shell coating with ZnS resulted in highly luminescent core-shell materials. The design and synthesis of P precursors for high-quality InP NQDs were conducted for the first time, and we were able to control the nucleation by varying the reactivity of P precursors, therefore achieving uniform large-sized InP NQDs. This opens the way for the large-scale production of high-quality Cd-free nanocrystal quantum dots. PMID:22289352

  10. Plasmonic thin film InP/graphene-based Schottky-junction solar cell using nanorods

    Directory of Open Access Journals (Sweden)

    Abedin Nematpour

    2018-03-01

    Full Text Available Herein, the design and simulation of graphene/InP thin film solar cells with a novel periodic array of nanorods and plasmonic back-reflectors of the nano-semi sphere was proposed. In this structure, a single-layer of the graphene sheet was placed on the vertical nanorods of InP to form a Schottky junction. The electromagnetic field was determined using solving three-dimensional Maxwell's equations discretized by the finite difference method (FDM. The enhancement of light trapping in the absorbing layer was illustrated, thereby increasing the short circuit current to a maximum value of 31.57 mA/cm2 with nanorods having a radius of 400 nm, height of 1250 nm, and nano-semi sphere radius of 50 nm, under a solar irradiation of AM1.5G. The maximum ultimate efficiency was determined to be 45.8% for an angle of incidence of 60°. This structure has shown a very good light trapping ability when graphene and ITO layers were used at the top and as a back-reflector in the proposed photonic crystal structure of the InP nanorods. Thence, this structure improves the short-circuit current density and the ultimate efficiency of 12% and 2.7%, respectively, in comparison with the InP-nanowire solar cells.

  11. Investigation of the transport properties and compositions of the Ca{sub 2}RE{sub 7}Pn{sub 5}O{sub 5} series (RE=Pr, Sm, Gd, Dy; Pn=Sb, Bi)

    Energy Technology Data Exchange (ETDEWEB)

    Forbes, Scott [Department of Chemistry and Chemical Biology, McMaster University, 1280 Main Street West, Hamilton, Ontario L8S 4M1 (Canada); Yuan, Fang [Department of Chemistry and Chemical Biology, McMaster University, 1280 Main Street West, Hamilton, Ontario L8S 4M1 (Canada); Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044 (Japan); Kosuda, Kosuke; Kolodiazhnyi, Taras [Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044 (Japan); Mozharivskyj, Yurij, E-mail: mozhar@mcmaster.ca [Department of Chemistry and Chemical Biology, McMaster University, 1280 Main Street West, Hamilton, Ontario L8S 4M1 (Canada)

    2016-10-15

    The Ca{sub 2}RE{sub 7}Pn{sub 5}O{sub 5} phases (RE=Pr, Sm, Gd, Dy; Pn=Sb, Bi) were successfully prepared from high temperature reactions at 1225–1300 °C. These phases maintain the same structure types as the parent RE{sub 9}Pn{sub 5}O{sub 5} phases, except for a Ca/RE mixing. The study and preparation of these phases was motivated by the desire to shift the metallic type properties of the parent RE{sub 9}Pn{sub 5}O{sub 5} phases to a level more suitable for thermoelectric applications. Electrical resistivity measurements performed on pure, bulk samples indicated all phases to be narrow band gap semiconductors or semimetals, supporting the charge balanced electron count of the Ca{sub 2}RE{sub 7}Pn{sub 5}O{sub 5} composition. Unfortunately, all samples are too electrically resistive for any potential usage as thermoelectrics. Electronic band structure calculations performed on idealized RE{sub 9}Pn{sub 5}O{sub 5} structures revealed the presence of a pseudogap at the Fermi level, which is consistent with the observed electrical resistivity and Seebeck coefficient behavior. - Graphical abstract: Ca substitution in RE{sub 9}Pn{sub 5}O{sub 5} leads to charge-balanced Ca{sub 2}RE{sub 7}Pn{sub 5}O{sub 5} phases with semiconducting or semimetallic properties. - Highlights: • The RE{sub 9}Pn{sub 5}O{sub 5} structure may be stabilized with calcium substitution in the form of Ca{sub 2}RE{sub 7}Pn{sub 5}O{sub 5}. • The Ca{sub 2}RE{sub 7}Pn{sub 5}O{sub 5} phases maintain the parent P 4/n structure, albeit with Ca/RE mixing. • The Ca{sub 2}RE{sub 7}Sb{sub 5}O{sub 5} phases behave as semiconductors while Ca{sub 2}RE{sub 7}Bi{sub 5}O{sub 5} are semimetals with electron-electron correlations. • Electronic structure calculations yield a semimetal-like density of states for both Ca{sub 2}RE{sub 7}Sb{sub 5}O{sub 5} and Ca{sub 2}RE{sub 7}Bi{sub 5}O{sub 5}.

  12. Design and optimization of the plasmonic graphene/InP thin-film solar-cell structure

    Science.gov (United States)

    Nematpour, Abedin; Nikoufard, Mahmoud; Mehragha, Rouholla

    2018-06-01

    In this paper, a graphene/InP thin-film Schottky-junction solar cell with a periodic array of plasmonic back-reflector is proposed. In this structure, a single-layer graphene sheet is deposited on the surface of the InP to form a Schottky junction. Then, the layer stack of the proposed solar-cell is optimized to have a maximum optical absorption of 〈A W〉  =  0.985 (98.5%) and short-circuit current density of J sc  =  33.01 mA cm‑2.

  13. Use of halide transport in epitaxial growth of InP and related compounds

    Energy Technology Data Exchange (ETDEWEB)

    Somogyi, K. [Hungarian Academy of Sciences, Budapest (Hungary). Research Inst. for Technical Physics

    1996-12-31

    In this paper methods and results in the InP (and related) growth practice are reviewed, classified and summarized on the basis of the recent literature. The aim is to show the present place and role of the halogen transport in the epitaxial growth. In the case of InP the importance of the classical hydride method is still high. Though MOVPE technique dominates in the case of growth of the compounds with In content, atomic layer epitaxy and selective area growth are successful with auxiliary application of the halogen transport. Chlorine assisted MOVPE has an increasing role.

  14. Chemical etching and polishing of InP

    International Nuclear Information System (INIS)

    Kurth, E.; Reif, A.; Gottschalch, V.; Finster, J.; Butter, E.

    1988-01-01

    This paper describes possibilities of several chemical preparations for the selective cleaning of InP surfaces. The investigations of the surface states after the chemical treatment were carried out by means of XPS measurements. A pre-etching with (NH 4 ) 2 S 2 O 8 :H 2 SO 4 :H 2 O and a polishing with 1% bromine in methanol produce optically smooth (100)-and (111) P surfaces free of oxides. (author)

  15. Homojunction p-n photodiodes based on As-doped single ZnO nanowire

    International Nuclear Information System (INIS)

    Cho, H. D.; Zakirov, A. S.; Yuldashev, Sh. U.; Kang, T. W.; Ahn, C. W.; Yeo, Y. K.

    2013-01-01

    Photovoltaic device was successfully grown solely based on the single ZnO p-n homojunction nanowire. The ZnO nanowire p-n diode consists of an as-grown n-type segment and an in-situ arsenic doped p-type segment. This p-n homojunction acts as a good photovoltaic cell, producing a photocurrent almost 45 times larger than the dark current under reverse-biased condition. Our results demonstrate that present ZnO p-n homojunction nanowire can be used as a self-powered ultraviolet photodetector as well as a photovoltaic cell, which can also be used as an ultralow electrical power source for nano-scale electronic, optoelectronic, and medical devices

  16. Characterization of a pnCCD for applications with synchrotron radiation

    Energy Technology Data Exchange (ETDEWEB)

    Send, S., E-mail: send@physik.uni-siegen.de [University of Siegen, Department of Physics, Walter-Flex-Straße 3, 57068 Siegen (Germany); Abboud, A. [University of Siegen, Department of Physics, Walter-Flex-Straße 3, 57068 Siegen (Germany); Hartmann, R.; Huth, M. [PNSensor GmbH, Römerstraße 28, 80803 München (Germany); Leitenberger, W. [University of Potsdam, Department of Physics, Karl-Liebknecht-Straße 24/25, 14476 Potsdam (Germany); Pashniak, N. [University of Siegen, Department of Physics, Walter-Flex-Straße 3, 57068 Siegen (Germany); Schmidt, J. [PNSensor GmbH, Römerstraße 28, 80803 München (Germany); Strüder, L. [University of Siegen, Department of Physics, Walter-Flex-Straße 3, 57068 Siegen (Germany); PNSensor GmbH, Römerstraße 28, 80803 München (Germany); Max-Planck-Institut für extraterrestrische Physik, Giessenbachstraße, 85748 Garching (Germany); Pietsch, U. [University of Siegen, Department of Physics, Walter-Flex-Straße 3, 57068 Siegen (Germany)

    2013-05-21

    In this work we study the response of a pnCCD by means of X-ray spectroscopy in the energy range between 6 keV and 20 keV and by Laue diffraction techniques. The analyses include measurements of characteristic detector parameters like energy resolution, count rate capability and effects of different gain settings. The limit of a single photon counting operation in white beam X-ray diffraction experiments is discussed with regard to the occurrence of pile-up events, for which the energy information about individual photons is lost. In case of monochromatic illumination the pnCCD can be used as a fast conventional CCD with a charge handling capacity (CHC) of about 300,000 electrons per pixel. If the CHC is exceeded, any surplus charge will spill to neighboring pixels perpendicular to the transfer direction due to electrostatic repulsion. The possibilities of increasing the number of storable electrons are investigated for different voltage settings by exposing a single pixel with X-rays generated by a microfocus X-ray source. The pixel binning mode is tested as an alternative approach that enables a pnCCD operation with significantly shorter readout times. -- Highlights: ► The pnCCD acts as a four-dimensional detector for white X-rays. ► Its performance for applications with synchrotron radiation is investigated. ► The pnCCD can be used for single photon counting and photon integration. ► The operation mode depends on the local frequencies of pile-up events. ► The pnCCD can be optimized for X-ray spectroscopy and X-ray imaging.

  17. Lattice defects in LPE InP-InGaAsP-InGaAs structure epitaxial layers on InP substrates

    International Nuclear Information System (INIS)

    Ishida, K.; Matsumoto, Y.; Taguchi, K.

    1982-01-01

    Lattice defects generated during LPE growth of InP-InGaAsP-InGaAs structure epitaxial layers on InP substrates are studied. Two different kinds of dislocations are observed at the two interfaces of the epitaxial layers; at the InP-InGaAsP interface, misfit dislocations are generated in the InP layer by carry over of InGaAsP melt into the InP one and at the InGaAs-InP interface, V-shaped dislocations are generated in the InGaAs layer. It is shown that the critical amount of lattice mismatch to suppress generation of misfit dislocations in InP is about two times smaller than that of other III-V compound semiconductors. Conditions to suppress the generation of these dislocations are clarified. (author)

  18. Impedance spectroscopy of CdTe thin film solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Weiss, Charlotte; Heisler, Christoph; Reisloehner, Udo; Ronning, Carsten; Wesch, Werner [Institute of Solid State Physics, University of Jena, Max-Wien-Platz 1, D-07743 Jena (Germany)

    2012-07-01

    Impedance Spectroscopy (IS) is a widely used method to analyze dielectric properties of specimen as a function of frequency. Typically this characterization method delivers an equivalent circuit diagram of the device under examination to describe its electrical properties. Traditionally IS is used in coating evaluation, corrosion monitoring and in electrochemistry. During the last years the method became more important also in the field of electrical characterization of solar cells. In our work we use IS for the electrical characterization of thin film CdTe solar cells. The measurement is done at room temperature without illumination in a frequency domain from 20 Hz to 2 MHz. The samples are measured under variable forward bias. The results match insufficiently with the model of two resistor-capacitor circuits in series which is commonly used to describe the p-n junction and the blocking back contact. For better consistency, other models from the literature are used and discussed. From the results a conclusion is drawn about the properties of the solar cell such as the nature of the p-n junction or the performance of the back contact.

  19. Post deposition annealing effect on the properties of Al2O3/InP interface

    Science.gov (United States)

    Kim, Hogyoung; Kim, Dong Ha; Choi, Byung Joon

    2018-02-01

    Post deposition in-situ annealing effect on the interfacial and electrical properties of Au/Al2O3/n-InP junctions were investigated. With increasing the annealing time, both the barrier height and ideality factor changed slightly but the series resistance decreased significantly. Photoluminescence (PL) measurements showed that the intensities of both the near band edge (NBE) emission from InP and defect-related bands (DBs) from Al2O3 decreased with 30 min annealing. With increasing the annealing time, the diffusion of oxygen (indium) atoms into Al2O3/InP interface (into Al2O3 layer) occurred more significantly, giving rise to the increase of the interface state density. Therefore, the out-diffusion of oxygen atoms from Al2O3 during the annealing process should be controlled carefully to optimize the Al2O3/InP based devices.

  20. Model of deep centers formation and reactions in electron irradiated InP

    International Nuclear Information System (INIS)

    Sibille, A.; Suski, J.; Gilleron, M.

    1986-01-01

    We present a model of the production of deep centers and their reactions following electron irradiations in InP. We propose that the dominant hole traps in p-InP and electron traps in p + n InP junctions are complexes between shallow acceptors and a common intrinsic entity, the phosphorus interstitial or vacancy. The reactions observed below and above room temperature are then due to a local mobility of this entity, which can be obtained as well by thermal as by electronic stimulation of the reactions. This model implies the long-range migration (at least down to 16 K) of this entity, and explains the strongly different behavior of n-InP compared to p-InP samples

  1. Fabrication and doping methods for silicon nano- and micropillar arrays for solar cell applications: a review

    NARCIS (Netherlands)

    Elbersen, R.; Vijselaar, Wouter Jan, Cornelis; Tiggelaar, Roald M.; Gardeniers, Johannes G.E.; Huskens, Jurriaan

    2015-01-01

    Silicon is one of the main components of commercial solar cells and is used in many other solar-light-harvesting devices. The overall efficiency of these devices can be increased by the use of structured surfaces that contain nanometer- to micrometer-sized pillars with radial p/n junctions. High

  2. Thermal crosstalk investigation in an integrated InP multiwavelength laser

    NARCIS (Netherlands)

    Gilardi, G.; Wale, M.J.; Smit, M.K.

    2012-01-01

    We numerically investigate the thermal crosstalk effects in an integrated InP multiwavelength laser. The multiwavelength laser under investigation consists of a number of Distributed Bragg Reflector lasers and an Arrayed Waveguide Grating. Each laser generates a fixed wavelength and the Arrayed

  3. Low-frequency photocurrent oscillations in InP in magnetic field

    International Nuclear Information System (INIS)

    Slobodchikov, S.V.; Salikhov, Kh.M.; Kovalevskaya, G.G.

    1994-01-01

    Results of investigations of magnetic field effect on the oscillating photocurrent in InP crytals are presented. It is shown that the magnetic field plays the part of an additional source of photocarrier injection in the sample bulk. 3 refs., 2 figs

  4. Novel Fractional Order Calculus Extended PN for Maneuvering Targets

    Directory of Open Access Journals (Sweden)

    Jikun Ye

    2017-01-01

    Full Text Available Based on the theory of fractional order calculus (FOC, a novel extended proportional guidance (EPN law for intercepting the maneuvering target is proposed. In the first part, considering the memory function and filter characteristic of FOC, the novel extended PN guidance algorithm is developed based on the conventional PN after introducing the properties and operation rules of FOC. Further, with the help of FOC theory, the average load and ballistics characteristics of proposed guidance law are analyzed. Then, using the small offset kinematic model, the robustness of the new guidance law against autopilot parameters is studied theoretically by analyzing the sensitivity of the closed loop guidance system. At last, representative numerical results show that the designed guidance law obtains a better performance than the traditional PN for maneuvering target.

  5. InGaAs/InP solar cells for space application

    Science.gov (United States)

    Karlina, L. B.; Kazantsev, A. B.; Kozlovskii, V. V.; Mokina, I. A.; Shvarts, M. Z.

    1995-01-01

    The effects of irradiation of In(0.53)Ga(0.47)As/InP (InGaAs/InP) solar cells illuminated through a transparent InP substrate with 1 MeV electrons were measured. These solar cells were developed for bottom cells in tandem solar photovoltaic cell structures. Some InGaAs/InP heterostructures with four layers were grown by liquid phase epitaxy. The structure of the solar cells allowed lightly doped materials in n and p photoactive layers to be used. The base dopant levels ranged from 1.10(exp 17) to 5.10(exp 17) cm(exp -3). The open circuit voltage and the short circuit current were moderately degraded after irradiation with 10(exp 16) cm(exp-2) 1 MeV electrons. This behavior is explained in terms of the device structure and the n and p layer thicknesses.

  6. Phosphorus-hydrogen complexes in LEC-grown InP

    Energy Technology Data Exchange (ETDEWEB)

    Ulrici, W. [Paul-Drude-Institut fuer Festkoerperelektronik, Hausvogteiplatz 5-7, 10117 Berlin (Germany); Kwasniewski, A.; Czupalla, M.; Neubert, M. [Institut fuer Kristallzuechtung, Max-Born-Str. 2, 12489 Berlin (Germany)

    2005-03-01

    In LEC-grown InP, about 30 sharp vibrational absorption lines are measured in the frequency region 2200 to 2350 cm{sup -1}. All these lines are due to phosphorus-hydrogen stretching modes. Experiments on InP containing both hydrogen and deuterium finally proved that the line at 2202.4 cm{sup -1} is due to a single hydrogen atom bonded to P in an indium vacancy (V{sub In}) and that the line at 2315.6 cm{sup -1} is due to the complex of four P-H bonds in an V{sub In}. In InP:H:D, this V{sub In}H{sub 4} complex gives rise to six vibrational lines in the region of P-H modes and six lines in the region of P-D modes because of the five different types of V{sub In}H{sub n}D{sub m} complexes. The measured frequencies of these 12 lines are in excellent agreement with those obtained from ab initio calculations reported in the literature. Additional P-H complexes are discussed. (copyright 2005 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  7. pnCCD for photon detection from near-infrared to X-rays

    International Nuclear Information System (INIS)

    Meidinger, Norbert; Andritschke, Robert; Hartmann, Robert; Herrmann, Sven; Holl, Peter; Lutz, Gerhard; Strueder, Lothar

    2006-01-01

    A pnCCD is a special type of charge-coupled device developed for spectroscopy and imaging of X-rays with high time resolution and quantum efficiency. Its most famous application is the operation on the XMM-Newton satellite, an X-ray astronomy mission that was launched by the European space agency in 1999. The excellent performance of the focal plane camera has been maintained for more than 6 years in orbit. The energy resolution in particular has shown hardly any degradation since launch. In order to satisfy the requirements of future X-ray astronomy missions as well as those of ground-based experiments, a new type of pnCCD has been developed. This 'frame-store pnCCD' shows an enhanced performance compared to the XMM-Newton type of pnCCD. Now, more options in device design and operation are available to tailor the detector to its respective application. Part of this concept is a programmable analog signal processor, which has been developed for the readout of the CCD signals. The electronic noise of the new detector has a value of only 2 electrons equivalent noise charge (ENC), which is less than half of the figure achieved for the XMM-Newton-type pnCCD. The energy resolution for the Mn-K α line at 5.9 keV is approximately 130 eV FWHM. We have close to 100% quantum efficiency for both low- and high-energy photon detection (e.g. the C-K line at 277 eV, and the Ge-K α line at 10 keV, respectively). Very high frame rates of 1000 images/s have been achieved due to the ultra-fast readout accomplished by the parallel architecture of the pnCCD and the analog signal processor. Excellent spectroscopic performance is shown even at the relatively high operating temperature of -25 deg. C that can be achieved by a Peltier cooler. The applications of the low-noise and fast pnCCD detector are not limited to the detection of X-rays. With an anti-reflective coating deposited on the photon entrance window, we achieve high quantum efficiency also for near-infrared and optical

  8. Pathway to 50% Efficient Inverted Metamorphic Concentrator Solar Cells

    Energy Technology Data Exchange (ETDEWEB)

    Geisz, John F [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Steiner, Myles A [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Jain, Nikhil [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Schulte, Kevin L [National Renewable Energy Laboratory (NREL), Golden, CO (United States); France, Ryan M [National Renewable Energy Laboratory (NREL), Golden, CO (United States); McMahon, William E [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Perl, Emmett [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Horowitz, Kelsey A [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Friedman, Daniel J [National Renewable Energy Laboratory (NREL), Golden, CO (United States)

    2017-09-06

    Series-connected five (5J) and six junction (6J) concentrator solar cell strategies have the realistic potential to exceed 50% efficiency to enable low-cost CPV systems. We propose three strategies for developing a practical 6J device. We have overcome many of the challenges required to build such concentrator solar cell devices: We have developed 2.1 eV AlGaInP, 1.7 eV AlGaAs, and 1.7 eV GaInAsP junctions with external radiative efficiency greater than 0.1%. We have developed a transparent tunnel junction that absorbs minimal light intended for the second junction yet resists degradation under thermal load. We have developed metamorphic grades from the GaAs to the InP lattice constant that are transparent to sub-GaAs bandgap light. We have grown and compared low bandgap junctions (0.7eV - 1.2 eV) using metamorphic GaInAs, metamorphic GaInAsP, and GaInAsP lattice-matched to InP. And finally, we have demonstrated excellent performance in a high voltage, low current 4 junction inverted metamorphic device using 2.1, 1.7, 1.4, and 1.1 eV junctions with over 8.7 mA/cm2 one-sun current density that operates up to 1000 suns without tunnel junction failure.

  9. Electronic structure and transport properties of Ba2Cd2Pn3 (Pn = As and Sb): An efficient materials for energy conversion

    International Nuclear Information System (INIS)

    Reshak, A.H.

    2016-01-01

    The full potential method within the recently modified Becke-Johnson potential explore that the Ba 2 Cd 2 Pn 3 (Pn = As and Sb) compounds are narrow band gap semiconductors of about 0.49 and 0.32 eV, which confute the finding of the previous TB-LMTO-ASA calculation that Ba 2 Cd 2 Sb 3 is a poor metal. It has been found that there are subtle difference in band desperations of the two compounds, resulting in significant influence on the electronic and transport properties, taking into account the size and the electro-negativity differences between As and Sb atoms. Calculation show that there exists a strong hybridization between the orbitals which may lead to form covalent bonding which is more favorable for the transport of the carriers than ionic one. The electronic structure, the anisotropy and the inter-atomic interactions are further analyzed by calculating the valence electronic charge density distribution in two crystallographic planes. The semi-classical Boltzmann theory as incorporated in BoltzTraP code was used to calculate the transport properties of Ba 2 Cd 2 As 3 and Ba 2 Cd 2 Sb 3 at different temperatures and chemical potentials to ascertain the influence of temperatures and substituting As by Sb on the transport properties. The carries mobility decreases with increasing the temperature also with increasing the carriers concentration. We have observed that substituting As by Sb lead to increase the carries mobility of Ba 2 Cd 2 Sb 3 along the whole temperature interval and the carries concentration range. It has been found that Ba 2 Cd 2 As 3 exhibit higher carriers concentration, electronic electrical conductivity and Seebeck coefficient than that of Ba 2 Cd 2 Sb 3 along the investigated temperature range. The highest value of Seebeck coefficient occurs at 300 K, which show good agreement with the experimental data. The power factor increases linearly with increasing the temperature and Ba 2 Cd 2 As 3 exhibit a bit higher power factor than that of Ba

  10. Evidence of mesoniums in anti pn annihilations and γγ reactions

    International Nuclear Information System (INIS)

    Liu, K.F.; Li, B.A.

    1987-01-01

    A new resonance at 1480 MeV with a width of 110 MeV is found in anti pn annihilations in the channel anti pn → π - X 0 (1480) → π - ρ 0 ρ 0 . Its mass, width and spin-parity are shown to be consistent with the ρ 0 ρ 0 enhancement observed in γγ reactions. Together with the suppression in the γγ → ρ + ρ - data which requires the admixture of an isotensor structure, this ρ 0 ρ 0 resonance in anti pn annihilation and γγ reactions and their small ππ branching ratios represent the best evidence yet for the Q 2 Q-bar 2 nature of the mesoniums. A ρ - ρ - resonance in anti pn annihilations which would betray the exotic isotensor nature of the resonance is predicted. (author)

  11. A new class of PN3-pincer ligands for metal–ligand cooperative catalysis

    KAUST Repository

    Li, Huaifeng

    2014-12-01

    Work on a new class of PN3-pincer ligands for metal-ligand cooperative catalysis is reviewed. While the field of the pyridine-based PN3-transition metal pincer complexes is still relatively young, many important applications of these complexes have already emerged. In several cases, the PN3-pincer complexes for metal-ligand cooperative catalysis result in significantly improved or unprecedented activities. The synthesis and coordination chemistry of PN3-pincer ligands are briefly summarized first to cover the synthetic routes for their preparation, followed by a focus review on their applications in catalysis. A specific emphasis is placed on the later section about the role of PN3-pincer ligands\\' dearomatization-rearomatization steps during the catalytic cycles. The mechanistic insights from density functional theory (DFT) calculations are also discussed.

  12. A new class of PN3-pincer ligands for metal–ligand cooperative catalysis

    KAUST Repository

    Li, Huaifeng; Zheng, Bin; Huang, Kuo-Wei

    2014-01-01

    Work on a new class of PN3-pincer ligands for metal-ligand cooperative catalysis is reviewed. While the field of the pyridine-based PN3-transition metal pincer complexes is still relatively young, many important applications of these complexes have already emerged. In several cases, the PN3-pincer complexes for metal-ligand cooperative catalysis result in significantly improved or unprecedented activities. The synthesis and coordination chemistry of PN3-pincer ligands are briefly summarized first to cover the synthetic routes for their preparation, followed by a focus review on their applications in catalysis. A specific emphasis is placed on the later section about the role of PN3-pincer ligands' dearomatization-rearomatization steps during the catalytic cycles. The mechanistic insights from density functional theory (DFT) calculations are also discussed.

  13. The influence of pressure on the birefringence in semiconductor compounds ZnS, CuGaS2, and InPS4

    International Nuclear Information System (INIS)

    Lavrentyev, A.A.; Gabrelian, B.V.; Kulagin, B.B.; Nikiforov, I.Ya.; Sobolev, V.V.

    2007-01-01

    Using the modified method of augmented plane waves and the code WIEN2k the calculations of the electron band structure, densities of electron states, and imaginary part of dielectric response function were carried out for different polarization of the vector of electrical field ε xx and ε zz for the semiconductor compounds ZnS, CuGaS 2 , and InPS 4 . The calculations were performed both for undisturbed crystals and for distorted crystals due to the applied pressure. The compounds studied have the similar crystallographic structures: ZnS - sphalerite, CuGaS 2 - chalcopyrite, and InPS 4 - twice defective chalcopyrite. It is known, that in cubic ZnS there is no birefringence, whereas in CuGaS 2 and InPS 4 there is one. But CuGaS 2 has so called isotropic point (where ε xx =ε zz ) in the visible optical range, and InPS 4 has no such point. Our calculations of ε xx and ε zz have shown that in ZnS under the pressure the isotropic points arise, but in InPS 4 they do not exist. (copyright 2007 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  14. Ternary CaCu{sub 4}P{sub 2}-type pnictides AAg{sub 4}Pn{sub 2} (A=Sr, Eu; Pn=As, Sb)

    Energy Technology Data Exchange (ETDEWEB)

    Stoyko, Stanislav S.; Khatun, Mansura; Scott Mullen, C. [Department of Chemistry, University of Alberta, Edmonton, Alberta, T6G 2G2 (Canada); Mar, Arthur, E-mail: arthur.mar@ualberta.ca [Department of Chemistry, University of Alberta, Edmonton, Alberta, T6G 2G2 (Canada)

    2012-08-15

    Four ternary pnictides AAg{sub 4}Pn{sub 2} (A=Sr, Eu; Pn=As, Sb) were prepared by reactions of the elements at 850 Degree-Sign C and their crystal structures were determined from single-crystal X-ray diffraction studies. These silver-containing pnictides AAg{sub 4}Pn{sub 2} adopt the trigonal CaCu{sub 4}P{sub 2}-type structure (Pearson symbol hR21, space group R3-bar m, Z=3; a=4.5555(6) A, c=24.041(3) A for SrAg{sub 4}As{sub 2}; a=4.5352(2) A, c=23.7221(11) A for EuAg{sub 4}As{sub 2}; a=4.7404(4) A, c=25.029(2) A for SrAg{sub 4}Sb{sub 2}; a=4.7239(3) A, c=24.689(2) A for EuAg{sub 4}Sb{sub 2}), which can be derived from the trigonal CaAl{sub 2}Si{sub 2}-type structure of the isoelectronic zinc-containing pnictides AZn{sub 2}Pn{sub 2} by insertion of additional Ag atoms into trigonal planar sites within [M{sub 2}Pn{sub 2}]{sup 2-} slabs built up of edge-sharing tetrahedra. Band structure calculations on SrAg{sub 4}As{sub 2} and SrAg{sub 4}Sb{sub 2} revealed that these charge-balanced Zintl phases actually exhibit no gap at the Fermi level and are predicted to be semimetals. - Graphical abstract: SrAg{sub 4}As{sub 2} and related pnictides adopt a CaCu{sub 4}P{sub 2}-type structure in which additional Ag atoms enter trigonal planar sites within slabs built from edge-sharing tetrahedra. Highlights: Black-Right-Pointing-Pointer AAg{sub 4}Pn{sub 2} are the first Ag-containing members of the CaCu{sub 4}P{sub 2}-type structure. Black-Right-Pointing-Pointer Ag atoms are stuffed in trigonal planar sites within CaAl{sub 2}Si{sub 2}-type slabs. Black-Right-Pointing-Pointer Ag-Ag bonding develops through attractive d{sup 10}-d{sup 10} interactions.

  15. High uniformity of self-organized InAs quantum wires on InAlAs buffers grown on misoriented InP(001)

    International Nuclear Information System (INIS)

    Wang Yuanli; Jin, P.; Ye, X.L.; Zhang, C.L.; Shi, G.X.; Li, R.Y.; Chen, Y.H.; Wang, Z.G.

    2006-01-01

    Highly uniform InAs quantum wires (QWRs) have been obtained on the In 0.5 Al 0.5 As buffer layer grown on the InP substrate 8 (convolutionsign) off (001) towards (111) by molecular-beam epitaxy. The quasi-periodic composition modulation was spontaneously formed in the In 0.5 Al 0.5 As buffer layer on this misoriented InP (001). The width and period of the In-rich bands are about 10 and 40 nm, respectively. The periodic In-rich bands play a major role in the sequent InAs QWRs growth and the InAs QWRs are well positioned atop In-rich bands. The photoluminescence (PL) measurements showed a significant reduction in full width at half maximum and enhanced PL efficiency for InAs QWRs on misoriented InP(001) as compared to that on normal InP(001)

  16. All-Optical 9.35 Gb/s Wavelength Conversion in an InP Photonic Crystal Nanocavity

    DEFF Research Database (Denmark)

    Vukovic, Dragana; Yu, Yi; Heuck, Mikkel

    2013-01-01

    Wavelength conversion of a 9.35 Gb/s RZ signal is demonstrated using an InP photonic crystal H0 nanocavity. A clear eye is observed for the converted signal showing a pre-FEC bit error ratio down to 10-3.......Wavelength conversion of a 9.35 Gb/s RZ signal is demonstrated using an InP photonic crystal H0 nanocavity. A clear eye is observed for the converted signal showing a pre-FEC bit error ratio down to 10-3....

  17. Charge exchange reactions and the efficiency of solar neutrino detectors

    International Nuclear Information System (INIS)

    Austin, S.M.; Anantaraman, N.; Love, W.G.

    1994-01-01

    The efficiencies of solar neutrino detectors are often based in part on weak interaction strengths determined by (p,n) and other charge exchange reactions. Although the (p,n) determinations are surprisingly good, it is shown that they may be inaccurate for important Gamow-Teller transitions whose strengths are a small fraction of the sum rule limit. This emphasizes the importance of direct calibration with ν sources for detectors such as 127 I and 115 In where direct β-decay information cannot be obtained. It may also bear on recent attempts to compare charge exchange and beta decay in the mass-37 system

  18. Formation mechanisms for the dominant kinks with different angles in InP nanowires.

    Science.gov (United States)

    Zhang, Minghuan; Wang, Fengyun; Wang, Chao; Wang, Yiqian; Yip, SenPo; Ho, Johnny C

    2014-01-01

    The morphologies and microstructures of kinked InP nanowires (NWs) prepared by solid-source chemical vapor deposition method were examined using scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HRTEM). Statistical analysis and structural characterization reveal that four different kinds of kinks are dominant in the grown InP NWs with a bending angle of approximately 70°, 90°, 110°, and 170°, respectively. The formation mechanisms of these kinks are discussed. Specifically, the existence of kinks with bending angles of approximately 70° and 110° are mainly attributed to the occurrence of stacking faults and nanotwins in the NWs, which could easily form by the glide of {111} planes, while approximately 90° kinks result from the local amorphorization of InP NWs. Also, approximately 170° kinks are mainly caused by small-angle boundaries, where the insertion of extra atomic planes could make the NWs slightly bent. In addition, multiple kinks with various angles are also observed. Importantly, all these results are beneficial to understand the formation mechanisms of kinks in compound semiconductor NWs, which could guide the design of nanostructured materials, morphologies, microstructures, and/or enhanced mechanical properties.

  19. Enhancement of radiation tolerance in GaAs/AlGaAs core–shell and InP nanowires

    Science.gov (United States)

    Li, Fajun; Xie, Xiaolong; Gao, Qian; Tan, Liying; Zhou, Yanping; Yang, Qingbo; Ma, Jing; Fu, Lan; Tan, Hark Hoe; Jagadish, Chennupati

    2018-06-01

    Radiation effects on semiconductor nanowires (NWs) have attracted the attention of the research community due to their potential applications in space and atomic fields. The effective implementation of NW devices in a radiation environment is a matter of concern. Here, the photoluminescence (PL) and time-resolved PL (TRPL) measurements were performed on both GaAs and InP NWs at room temperature before and after 1 MeV H+ irradiation with fluences ranging from 1 × 1011 to 5 × 1013 p cm‑2. It is found that the degradation of lifetime is size-dependent, and typically the minority carrier lifetime damage coefficient is closely correlated with the material and NW diameter. Compared to GaAs and InP bulk material counterparts, the lifetime damage coefficient of NWs decreases by a factor of about one order of magnitude. After irradiation, GaAs NWs with a smaller diameter show a much lower lifetime damage coefficient while InP NWs show an increase in carrier radiative lifetime. The increased size-dependent radiation hardness is mainly attributed to the defect sink effect and/or the improvement of a room temperature dynamic annealing mechanism of the NWs. The InP NWs also showed higher radiation tolerance than GaAs NWs.

  20. Enhancement of radiation tolerance in GaAs/AlGaAs core-shell and InP nanowires.

    Science.gov (United States)

    Li, Fajun; Xie, Xiaolong; Gao, Qian; Tan, Liying; Zhou, Yanping; Yang, Qingbo; Ma, Jing; Fu, Lan; Tan, Hark Hoe; Jagadish, Chennupati

    2018-06-01

    Radiation effects on semiconductor nanowires (NWs) have attracted the attention of the research community due to their potential applications in space and atomic fields. The effective implementation of NW devices in a radiation environment is a matter of concern. Here, the photoluminescence (PL) and time-resolved PL (TRPL) measurements were performed on both GaAs and InP NWs at room temperature before and after 1 MeV H + irradiation with fluences ranging from 1 × 10 11 to 5 × 10 13 p cm -2 . It is found that the degradation of lifetime is size-dependent, and typically the minority carrier lifetime damage coefficient is closely correlated with the material and NW diameter. Compared to GaAs and InP bulk material counterparts, the lifetime damage coefficient of NWs decreases by a factor of about one order of magnitude. After irradiation, GaAs NWs with a smaller diameter show a much lower lifetime damage coefficient while InP NWs show an increase in carrier radiative lifetime. The increased size-dependent radiation hardness is mainly attributed to the defect sink effect and/or the improvement of a room temperature dynamic annealing mechanism of the NWs. The InP NWs also showed higher radiation tolerance than GaAs NWs.

  1. Solution-grown organic single-crystalline p-n junctions with ambipolar charge transport.

    Science.gov (United States)

    Fan, Congcheng; Zoombelt, Arjan P; Jiang, Hao; Fu, Weifei; Wu, Jiake; Yuan, Wentao; Wang, Yong; Li, Hanying; Chen, Hongzheng; Bao, Zhenan

    2013-10-25

    Organic single-crystalline p-n junctions are grown from mixed solutions. First, C60 crystals (n-type) form and, subsequently, C8-BTBT crystals (p-type) nucleate heterogeneously on the C60 crystals. Both crystals continue to grow simultaneously into single-crystalline p-n junctions that exhibit ambipolar charge transport characteristics. This work provides a platform to study organic single-crystalline p-n junctions. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Charge exchange probes of nuclear structure and interactions with emphasis on (p,n)

    International Nuclear Information System (INIS)

    Goodman, C.D.

    1980-01-01

    New results from (p,n) studies at IUCF show that it is possible to observe Gamow-Teller (GT) strength and extract GT matrix elements from (p,n) measurements. The charge exchange reactions ( 6 Li, 6 He) and (π + ,π 0 ) involve different projectile quantum numbers, and the relationships of these reactions to (p,n) is discussed

  3. Experimental analysis and modeling of the IV characteristics of photovoltaic solar cells under solar spectrum spot illumination

    Energy Technology Data Exchange (ETDEWEB)

    Munji, M.K., E-mail: mathew.munji@nmmu.ac.z [Department of Physics, Nelson Mandela Metropolitan University, PO Box 7700 Port Elizabeth 6031 (South Africa); Dyk, E.E. van; Vorster, F.J. [Department of Physics, Nelson Mandela Metropolitan University, PO Box 7700 Port Elizabeth 6031 (South Africa)

    2009-12-01

    In this paper, some models that have been put forward to explain the characteristics of a photovoltaic solar cell device under solar spot-illumination are investigated. In the experimental procedure, small areas of the cell were selected and illuminated at different solar intensities. The solar cell open circuit voltage (V{sub oc}) and short circuit current (I{sub sc}) obtained at different illumination intensities was used to determine the solar cell ideality factor. By varying the illuminated area on the solar cell, changes in the ideality factor were studied. The ideality factor obtained increases with decreasing illumination surface ratio. The photo-generated current at the illuminated part of the cell is assumed to act as a dc source that injects charge carriers into the p-n junction of the whole solar cell while the dark region of the solar cell operates in a low space charge recombination regime with small diffusion currents. From this analysis, a different model of a spot illuminated cell that uses the variation of ideality factor with the illuminated area is proposed.

  4. Experimental analysis and modeling of the IV characteristics of photovoltaic solar cells under solar spectrum spot illumination

    International Nuclear Information System (INIS)

    Munji, M.K.; Dyk, E.E. van; Vorster, F.J.

    2009-01-01

    In this paper, some models that have been put forward to explain the characteristics of a photovoltaic solar cell device under solar spot-illumination are investigated. In the experimental procedure, small areas of the cell were selected and illuminated at different solar intensities. The solar cell open circuit voltage (V oc ) and short circuit current (I sc ) obtained at different illumination intensities was used to determine the solar cell ideality factor. By varying the illuminated area on the solar cell, changes in the ideality factor were studied. The ideality factor obtained increases with decreasing illumination surface ratio. The photo-generated current at the illuminated part of the cell is assumed to act as a dc source that injects charge carriers into the p-n junction of the whole solar cell while the dark region of the solar cell operates in a low space charge recombination regime with small diffusion currents. From this analysis, a different model of a spot illuminated cell that uses the variation of ideality factor with the illuminated area is proposed.

  5. Investigation of semi-insulating InP co-doped with Ti and various acceptors for use in X-ray detection

    International Nuclear Information System (INIS)

    Zdansky, K.; Gorodynskyy, V.; Kozak, H.; Pekarek, L.

    2005-01-01

    Semi-insulating InP single crystals co-doped with Zn and Ti and co-doped with Ti and Mn were grown by Czochralski technique. Wafers of these crystals were annealed for a long time at a high temperature and cooled slowly. The samples were characterized by temperature dependent resistivity and Hall coefficient measurements. The binding energies of Ti in semi-insulating InP co-doped with Ti and Zn and co-doped with Ti and Mn were found to differ which shows that Ti may occupy different sites in InP. The curves of Hall coefficient vs. reciprocal temperature deviate from straight lines at low temperatures due to electron and hole mixed conductance. The value of resistivity of the annealed semi-insulating InP co-doped with Ti and Mn reaches high resistivity at a reduced temperature easily achievable by thermo-electric devices which could make this material useable in X-ray detection. (copyright 2005 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  6. Highly doped InP as a low loss plasmonic material for mid-IR region.

    Science.gov (United States)

    Panah, M E Aryaee; Takayama, O; Morozov, S V; Kudryavtsev, K E; Semenova, E S; Lavrinenko, A V

    2016-12-12

    We study plasmonic properties of highly doped InP in the mid-infrared (IR) range. InP was grown by metal-organic vapor phase epitaxy (MOVPE) with the growth conditions optimized to achieve high free electron concentrations by doping with silicon. The permittivity of the grown material was found by fitting the calculated infrared reflectance spectra to the measured ones. The retrieved permittivity was then used to simulate surface plasmon polaritons (SPPs) propagation on flat and structured surfaces, and the simulation results were verified in direct experiments. SPPs at the top and bottom interfaces of the grown epilayer were excited by the prism coupling. A high-index Ge hemispherical prism provides efficient coupling conditions of SPPs on flat surfaces and facilitates acquiring their dispersion diagrams. We observed diffraction into symmetry-prohibited diffraction orders stimulated by the excitation of surface plasmon-polaritons in a periodically structured epilayer. Characterization shows good agreement between the theory and experimental results and confirms that highly doped InP is an effective plasmonic material aiming it for applications in the mid-IR wavelength range.

  7. X-ray diffraction analysis of multilayer porous InP(001) structure

    Czech Academy of Sciences Publication Activity Database

    Lomov, A. A.; Punegov, V. I.; Vasil'ev, A. L.; Nohavica, Dušan; Gladkov, Petar; Kartsev, A. A.; Novikov, D. V.

    2010-01-01

    Roč. 55, č. 2 (2010), s. 182-190 ISSN 1063-7745 Institutional research plan: CEZ:AV0Z20670512 Keywords : silicon layers * INP Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering Impact factor: 0.644, year: 2010

  8. Roadmap for integration of InP based photonics and silicon electronics

    NARCIS (Netherlands)

    Williams, K.A.

    2015-01-01

    We identify the synergies and a roadmap for the intimate integration of InP photonic integrated circuits and Silicon electronic ICs using wafer-scale processes. Advantages are foreseen in terms of bandwidth, energy savings and package simplification.

  9. Peculiarities of defect formation in InP single crystals doped with donor (S, Ge) and acceptor (Zn) impurities

    International Nuclear Information System (INIS)

    Morozov, A.N.; Mikryukova, E.V.; Bublik, V.T.; Berkova, A.V.; Nashel'skij, A.Ya.; Yakobson, S.V.

    1988-01-01

    Effect of alloying with donor (S,Ge) and acceptor (Zn) impurities on the concentration of proper point defects in monocrystals InP grown up from equiatomic (relative to In and P) melts by the Czochralski method under flux layer is investigated. Changes in boundary positions of the InP homogeneity region caused by alloying are analysed on the basis of experimental results according to the precision measurement of the lattice parameter and crystal density, as well as measurements of the Hall concentration of charge carriers and their mobility. The concentrations of Frenkel nonequilibrium (V in -In i ) defects formed in the initial stage of indium solid solution decomposition in InP are estimated

  10. Development of III-Sb Quantum Dot Systems for High Efficiency Intermediate Band Solar Cells

    Energy Technology Data Exchange (ETDEWEB)

    Huffaker, Diana [Univ. of California, Los Angeles, CA (United States); Hubbard, Seth [Rochester Inst. of Technology, NY (United States); Norman, Andrew [National Renewable Energy Lab. (NREL), Golden, CO (United States)

    2015-07-31

    This project aimed to develop solar cells that can help reduce cost per watt. This work focused on developing solar cells that utilize quantum dot (QD) nanomaterials to provide multijunction solar cell efficiency at the cost of single junction solar cell. We focused on a novel concept known as intermediate band solar cells (IBSC) where an additional energy band is inserted in a single solar cell to accommodate sub-bandgap photons absorption which otherwise are lost through transmission. The additional energy band can be achieved by growing QDs within a solar cell p-n junction. Though numerous studies have been conducted to develop such QD systems, very small improvements in solar energy conversion efficiency have been reported. This is mainly due to non-optimal material parameters such as band gap, band offset etc. In this work, we identified and developed a novel QD material system that meets the requirements of IBSC more closely than the current state-of-the-art technology. To achieve these goals, we focused on three important areas of solar cell design: band structure calculations of new materials, efficient device design for high efficiency, and development of new semiconductor materials. In this project, we focused on III-Sb materials as they possess a wide range of energy bandgaps from 0.2 eV to 2eV. Despite the difficulty involved in realizing these materials, we were successfully developed these materials through a systematic approach. Materials studied in this work are AlAsSb (Aluminum Arsenide Antimonide), InAlAs (Indium Aluminum Arsenide) and InAs (Indium Arsenide). InAs was used to develop QD layers within AlAsSb and InAlAs p-n junctions. As the QDs have very small volume, up to 30 QD layers been inserted into the p-n junction to enhance light absorption. These QD multi-stack devices helped in understanding the challenges associated with the development of quantum dot solar cells. The results from this work show that the quantum dot solar cells indeed

  11. Mid-IR optical properties of silicon doped InP

    DEFF Research Database (Denmark)

    Panah, Mohammad Esmail Aryaee; Han, Li; Norrman, Kion

    2017-01-01

    of growth conditions on the optical and electrical properties of silicon doped InP (InP:Si) in the wavelength range from 3 to 40 μm was studied. The carrier concentration of up to 3.9 × 1019 cm-3 is achieved by optimizing the growth conditions. The dielectric function, effective mass of electrons and plasma...

  12. Tandem photovoltaic solar cells and increased solar energy conversion efficiency

    Science.gov (United States)

    Loferski, J. J.

    1976-01-01

    Tandem photovoltaic cells, as proposed by Jackson (1955) to increase the efficiency of solar energy conversion, involve the construction of a system of stacked p/n homojunction photovoltaic cells composed of different semiconductors. It had been pointed out by critics, however, that the total power which could be extracted from the cells in the stack placed side by side was substantially greater than the power obtained from the stacked cells. A reexamination of the tandem cell concept in view of the development of the past few years is conducted. It is concluded that the use of tandem cell systems in flat plate collectors, as originally envisioned by Jackson, may yet become feasible as a result of the development of economically acceptable solar cells for large scale terrestrial power generation.

  13. Effect of Fe inter-diffusion on properties of InP layers grown with addition of RE elements

    International Nuclear Information System (INIS)

    Prochazkova, O.; Zavadil, J.; Zdansky, K.

    2005-01-01

    This contribution reports the redistribution behaviour of Fe during the growth of InP layers from liquid phase with addition of some rare earth elements on semi-insulating InP:Fe substrates. We have studied the influence of different rare earths on the Fe diffusion into InP layer and compared it with the phenomenon of an extraction of iron from Fe doped materials into adjacent layers doped by Zn, Cd and Be, reported recently. In the case of Tm addition a conversion of electrical conductivity of InP layer to semi-insulating as a consequence of Fe diffusion has been observed while no significant Fe inter-diffusion has been confirmed in the presence of other investigated rare earth additions. (copyright 2005 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  14. Effects of adding butyric acid to PN on gut-associated lymphoid tissue and mucosal immunoglobulin A levels.

    Science.gov (United States)

    Murakoshi, Satoshi; Fukatsu, Kazuhiko; Omata, Jiro; Moriya, Tomoyuki; Noguchi, Midori; Saitoh, Daizoh; Koyama, Isamu

    2011-07-01

    Parenteral nutrition (PN) causes intestinal mucosal atrophy, gut-associated lymphoid tissue (GALT) atrophy and dysfunction, leading to impaired mucosal immunity and increased susceptibility to infectious complications. Therefore, new PN formulations are needed to maintain mucosal immunity. Short-chain fatty acids have been demonstrated to exert beneficial effects on the intestinal mucosa. We examined the effects of adding butyric acid to PN on GALT lymphocyte numbers, phenotypes, mucosal immunoglobulin A (IgA) levels, and intestinal morphology in mice. Male Institute of Cancer Research mice (n = 103) were randomized to receive either standard PN (S-PN), butyric acid-supplemented PN (Bu-PN), or ad libitum chow (control) groups. The mice were fed these respective diets for 5 days. In experiment 1, cells were isolated from Peyer's patches (PPs) to determine lymphocyte numbers and phenotypes (αβTCR(+), γδTCR(+), CD4(+), CD8(+), B220(+) cells). IgA levels in small intestinal washings were also measured. In experiment 2, IgA levels in respiratory tract (bronchoalveolar and nasal) washings were measured. In experiment 3, small intestinal morphology was evaluated. Lymphocyte yields from PPs and small intestinal, bronchoalveolar, and nasal washing IgA levels were all significantly lower in the S-PN group than in the control group. Bu-PN moderately, but significantly, restored PP lymphocyte numbers, as well as intestinal and bronchoalveolar IgA levels, as compared with S-PN. Villous height and crypt depth in the small intestine were significantly decreased in the S-PN group vs the control group, however Bu-PN restored intestinal morphology. A new PN formula containing butyric acid is feasible and would ameliorate PN-induced impairment of mucosal immunity.

  15. Electronic properties of wurtzite-phase InP nanowires determined by optical and magneto-optical spectroscopy

    Science.gov (United States)

    De Luca, Marta; Polimeni, Antonio

    2017-12-01

    Thanks to their peculiar shape and dimensions, semiconductor nanowires (NWs) are emerging as building components of novel devices. The presence of wurtzite (WZ) phase in the lattice structure of non-nitride III-V NWs is one of the most surprising findings in these nanostructures: this phase, indeed, cannot be found in the same materials in the bulk form, where the zincblende (ZB) structure is ubiquitous, and therefore the WZ properties are poorly known. This review focuses on WZ InP NWs, because growth techniques have reached a high degree of control on the structural properties of this material, and optical studies performed on high-quality samples have allowed determining the most useful electronic properties, which are reviewed here. After an introduction summarizing the reasons for the interest in WZ InP nanowires (Sec. I), we give an overview on growth process and structural and optical properties of WZ InP NWs (Sec. II). In Sec. III, a complete picture of the energy and symmetry of the lowest-energy conduction and valence bands, as assessed by polarization-resolved photoluminescence (PL) and photoluminescence-excitation (PLE) studies is drawn and compared to all the available theoretical information. The elastic properties of WZ InP (determined by PL under hydrostatic pressure) and the radiative recombination dynamics of spatially direct and indirect (namely, occurring across the WZ/ZB interfaces) transitions are also discussed. Section IV, focuses on the magneto-optical studies of WZ InP NWs. The diagram of the energy levels of excitons in WZ materials—with and without magnetic field—is first provided. Then, all theoretical and experimental information available about the changes in the transport properties (i.e., carrier effective mass) caused by the ZB→WZ phase variation are reviewed. Different NW/magnetic field geometrical configurations, sensitive to polarization selection rules, highlight anisotropies in the diamagnetic shifts, Zeeman splitting

  16. Design procedure for millimeter-wave InP DHBT stacked power amplifiers

    DEFF Research Database (Denmark)

    Squartecchia, Michele; Johansen, Tom Keinicke; Midili, Virginio

    2015-01-01

    The stacked-transistor concept for power amplifiers (PA) has been investigated in this work. Specifically, this architecture has been applied in the design of millimeter-wave monolithic microwave integrated circuits (MMICs) using indium phosphide (InP) double heterojunction bipolar transistors...

  17. InP integrated photonics : state of the art and future directions

    NARCIS (Netherlands)

    Williams, Kevin

    2017-01-01

    InP integrated circuits enable transceiver technologies with more than 200Gb/s per wavelength and 2Tb/s per fiber. Advances in monolithic integration are poised to reduce energy. remove assembly complexity, and sustain future year-on-year performance increases.

  18. The delicate electronic and magnetic structure of the LaFePnO system (Pn = pnicogen)

    Energy Technology Data Exchange (ETDEWEB)

    Lebegue, S [Laboratoire de Cristallographie et de Modelisation des Materiaux Mineraux et Biologiques, UMR 7036, CNRS-Universite Henri Poincare, BP 239, F-54506 Vandoeuvre-les-Nancy (France); Yin, Z P; Pickett, W E [Department of Physics, University of California Davis, Davis, CA 95616 (United States)], E-mail: sebastien.lebegue@lcm3b.uhp-nancy.fr

    2009-02-15

    The occurrence of high-temperature superconductivity, and the competition with magnetism, in stoichiometric and doped LaFeAsO and isostructural iron oxypnictides is raising many fundamental questions about the electronic structure and magnetic interactions in this class of materials. There are now sufficient experimental data that it may be possible to identify the important issues whose resolution will lead to the understanding of this system. In this paper, we address a number of the important issues. One important characteristic is the Fe-As distance (or more abstractly the pnicogen (Pn) height z(Pn)); we present results for the effect of z(Pn) on the electronic structure, energetics and Fe magnetic moment. We also study LaFeAsO under pressure, and investigate the effects of both electron and hole doping within the virtual crystal approximation. The electric field gradients for all atoms in the LaFeAsO compound are presented (undoped and doped) and compared with available data. The observed ({pi}, {pi}, {pi}) magnetic order is studied and compared with the computationally simpler ({pi}, {pi}, 0) order which is probably a very good model in most respects. We investigate the crucial role of the pnicogen atom in this class, and predict the structures and properties of the N and Sb counterparts that have not yet been reported experimentally. At a certain volume a gap opens at the Fermi level in LaFeNO, separating bonding from antibonding bands. This is the first evidence that this class of materials indeed has an underlying semimetallic character, and this separation suggests directions for a better simple understanding of the seemingly intricate electronic structure of this system. Finally, we address briefly differences resulting from substitution of post-lanthanum rare earth atoms, which have been observed to enhance the superconducting critical temperature substantially.

  19. Label swapper device for spectral amplitude coded optical packet networks monolithically integrated on InP.

    Science.gov (United States)

    Muñoz, P; García-Olcina, R; Habib, C; Chen, L R; Leijtens, X J M; de Vries, T; Robbins, D; Capmany, J

    2011-07-04

    In this paper the design, fabrication and experimental characterization of an spectral amplitude coded (SAC) optical label swapper monolithically integrated on Indium Phosphide (InP) is presented. The device has a footprint of 4.8x1.5 mm2 and is able to perform label swapping operations required in SAC at a speed of 155 Mbps. The device was manufactured in InP using a multiple purpose generic integration scheme. Compared to previous SAC label swapper demonstrations, using discrete component assembly, this label swapper chip operates two order of magnitudes faster.

  20. InP Devices For Millimeter-Wave Monolithic Circuits

    Science.gov (United States)

    Binari, S. C.; Neidert, R. E.; Dietrich, H. B.

    1989-11-01

    High efficiency, mm-wave operation has been obtained from lateral transferred-electron devices (TEDs) designed with a high resistivity region located near the cathode contact. At 29.9 GHz, a CW power output of 29.1 mW with a conversion efficiency of 6.7% has been achieved with cavity-tuned discrete devices. This result represents the highest power output and efficiency of a lateral TED in this frequency range. The lateral devices also had a CW power output of 0.4 mW at 98.5 GHz and 0.9 mW at 75.2 GHz. In addition, a monolithic oscillator incorporating the lateral TED has been demonstrated at 79.9 GHz. InP Schottky-barrier diodes have been fabricated using selective MeV ion implantation into semi-insulating InP substrates. Using Si implantation with energies of up to 6.0 MeV, n+ layers as deep as 3 μm with peak carrier concentrations of 2 x 1018 cm-3 have been obtained. These devices have been evaluated as mixers and detectors at 94 GHz and have demonstrated a conversion loss of 7.6 dB and a zero-bias detector sensitivity as high as 400 mV/mW.

  1. Solvothermal synthesis of InP quantum dots and their enhanced luminescent efficiency by post-synthetic treatments.

    Science.gov (United States)

    Byun, Ho-June; Lee, Ju Chul; Yang, Heesun

    2011-03-01

    InP quantum dots (QDs) were solvothermally synthesized by using a greener phosphorus source of P(N(CH(3))(2))(3) instead of highly toxic P(TMS)(3) widely used, and subsequently subjected to a size-sorting processing. While as-grown QDs showed an undetectably low emission intensity, post-synthetic treatments such as photo-etching, photo-radiation, and photo-assisted ZnS shell coating gave rise to a substantial increase in emission efficiency due to the effective removal and passivation of surface states. The emission efficiency of the photo-etched QDs was further enhanced by a consecutive UV photo-radiation, attributable to the photo-oxidation at QD surface. Furthermore, a relatively thick ZnS shell on the surface of InP QDs that were surface-modified with hydrophilic ligands beforehand was photochemically generated in an aqueous solution at room temperature. The resulting InP/ZnS core/shell QDs, emitting from blue to red wavelengths, were more efficient than the above photo-treated InP QDs, and their luminescent properties (emission bandwidth and quantum yield) were comparable to those of InP QDs synthesized with P(TMS)(3). Structural, size, and compositional analyses on InP/ZnS QDs were also conducted to elucidate their core/shell structure. Copyright © 2010 Elsevier Inc. All rights reserved.

  2. Electronic properties of pure and p-type doped hexagonal sheets and zigzag nanoribbons of InP

    International Nuclear Information System (INIS)

    Longo, R C; Carrete, J; Alemany, M M G; Gallego, L J

    2013-01-01

    Unlike graphene, a hexagonal InP sheet (HInPS) cannot be obtained by mechanical exfoliation from the native bulk InP, which crystallizes in the zinc blende structure under ambient conditions. However, by ab initio density functional theory calculations we found that a slightly buckled HInPS is stable both in pristine form and when doped with Zn atoms; the same occurred for hydrogen-passivated zigzag InP nanoribbons (ZInPNRs), quasi-one-dimensional versions of the quasi-two-dimensional material. We investigated the electronic properties of both nanostructures, in the latter case also in the presence of an external transverse electric field, and the results are compared with those of hypothetical planar HInPS and ZInPNRs. The band gaps of planar ZInPNRs were found to be tunable by the choice of strength of this field, and to show an asymmetric behavior under weak electric fields, by which the gap can either be increased or decreased depending on their direction; however, this effect is absent from slightly buckled ZInPNRs. The binding energies of the acceptor impurity states of Zn-doped HInPS and ZInPNRs were found to be similar and much larger than that of Zn-doped bulk InP. These latter findings show that the reduction of the dimensionality of these materials limits the presence of free carriers. (paper)

  3. Antiperovskite nitridophosphate oxide Ho{sub 3}[PN{sub 4}]O by high-pressure metathesis

    Energy Technology Data Exchange (ETDEWEB)

    Kloss, Simon D.; Weidmann, Niels; Schnick, Wolfgang [Department of Chemistry, University of Munich (LMU), Butenandtstrasse 5-13, 81377, Munich (Germany)

    2017-04-03

    Rare-earth nitridophosphates are a recently discovered class of materials, which are accessible by high-pressure metathesis. Antiperovskite-type Ho{sub 3}[PN{sub 4}]O was synthesized from HoF{sub 3}, LiPN{sub 2}, Li{sub 3}N, and Li{sub 2}O at 5 GPa and ca. 1025 C by this method and the multianvil technique. Ho{sub 3}[PN{sub 4}]O contains rarely observed isolated PN{sub 4} tetrahedra and can be derived by the hierarchical substitution of the ABX{sub 3} perovskite, in which Ho occupies the X positions, O occupies the B position, and the PN{sub 4} tetrahedra occupy the A position. The structure was refined on the basis of powder diffraction data [I4/mcm, a = 6.36112(3), c = 10.5571(1) Aa, Z = 4, R{sub wp} = 0.04, R{sub Bragg} = 0.01, χ{sup 2} = 2.275] starting from the structural model of isotypic Gd{sub 3}[SiN{sub 3}O]O. To characterize Ho{sub 3}[PN{sub 4}]O, elemental analyses were performed through energy-dispersive X-ray spectroscopy (EDX) and inductively coupled plasma optical emission spectroscopy (ICP-OES). Ho{sub 3}[PN{sub 4}]O is paramagnetic down to low temperatures with μ{sub eff} = 10.43(1) μ{sub B} and a Curie temperature (Θ) of 0.11(4) K. It shows the optical characteristics of Ho{sup 3+} ions and vibrations corresponding to isolated PN{sub 4} tetrahedra. On the basis of DFT calculations [generalized gradient approximation (GGA)], Ho{sub 3}[PN{sub 4}]O has an indirect band gap of 1.87 eV. We demonstrate the versatility of high-pressure metathesis by attaining the low end of the P/N atomic ratio κ = 1/4. This confirms the previous assumption that rare-earth nitridophosphates with κ = 1/2 to 1/4 are feasible by this method. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  4. Transient behavior of interface state continuum at InP insulator-semiconductor interface

    International Nuclear Information System (INIS)

    Hasegawa, H.; Masuda, H.; He, L.; Luo, J.K.; Sawada, T.; Ohno, H.

    1987-01-01

    To clarify the drain current drift mechanism in InP MISFETs, an isothermal capacitance transient spectroscopy (ICTS) study of the interface state continuum is made on the anodic Al 2 O 3 /native oxide/ InP MIS system. Capture behavior is temperature-independent, non-exponential and extremely slow, whereas emission behavior is temperature- and bias- dependent, and is much faster. The observed behavior is explained quantitatively by the disorder induced gap state (DIGS) model, where states are distributed both in energy and in space. By comparing the transient behavior of interface states with the observed drift behavior of MISFETs, it is concluded that the electron capture by the DIGS continuum is responsible for the drain current drift of MISFETs. This led to a complete computer simulation of the observed current drift behavior

  5. Peculiarities of defect formation in InP single crystals doped with donor (S, Ge) and acceptor (Zn) impurities

    International Nuclear Information System (INIS)

    Mikryukova, E.V.; Morozov, A.N.; Berkova, A.V.; Nashel'skij, A.Ya.; Yakobson, S.V.

    1988-01-01

    Peculiarities of dislocation and microdefect formation in InP monocrystals doped with donor (S,Ge) and acceptor (Zn) impurities are investigated by the metallography. Dependence of dislocation density on the concentration of alloying impurity is established. Microdefects leading to the appearance of 5 different types of etch figures are shown to be observed in doped InP monocrystals. The mechanism of microdefect formation is suggested

  6. Microscopic optoelectronic defectoscopy of solar cells

    Directory of Open Access Journals (Sweden)

    Dallaeva D.

    2013-05-01

    Full Text Available Scanning probe microscopes are powerful tool for micro- or nanoscale diagnostics of defects in crystalline silicon solar cells. Solar cell is a large p-n junction semiconductor device. Its quality is strongly damaged by the presence of defects. If the cell works under low reverse-biased voltage, defects emit a light in visible range. The suggested method combines three different measurements: electric noise measurement, local topography and near-field optical beam induced current and thus provides more complex information. To prove its feasibility, we have selected one defect (truncated pyramid in the sample, which emitted light under low reverse-biased voltage.

  7. Engineered nanomaterials for solar energy conversion.

    Science.gov (United States)

    Mlinar, Vladan

    2013-02-01

    Understanding how to engineer nanomaterials for targeted solar-cell applications is the key to improving their efficiency and could lead to breakthroughs in their design. Proposed mechanisms for the conversion of solar energy to electricity are those exploiting the particle nature of light in conventional photovoltaic cells, and those using the collective electromagnetic nature, where light is captured by antennas and rectified. In both cases, engineered nanomaterials form the crucial components. Examples include arrays of semiconductor nanostructures as an intermediate band (so called intermediate band solar cells), semiconductor nanocrystals for multiple exciton generation, or, in antenna-rectifier cells, nanomaterials for effective optical frequency rectification. Here, we discuss the state of the art in p-n junction, intermediate band, multiple exciton generation, and antenna-rectifier solar cells. We provide a summary of how engineered nanomaterials have been used in these systems and a discussion of the open questions.

  8. Growth of semiconductor alloy InGaPBi on InP by molecular beam epitaxy

    International Nuclear Information System (INIS)

    Wang, K; Wang, P; Pan, W W; Wu, X Y; Yue, L; Gong, Q; Wang, S M

    2015-01-01

    We report the first successful growth of InGaPBi single crystals on InP substrate with Bi concentration far beyond the doping level by gas source molecular beam epitaxy. The InGaPBi thin films reveal excellent surface and structural qualities, making it a promising new III–V compound family member for heterostructures. The strain can be tuned between tensile and compressive by adjusting Ga and Bi compositions. The maximum achieved Bi concentration is 2.2 ± 0.4% confirmed by Rutherford backscattering spectroscopy. Room temperature photoluminescence shows strong and broad light emission at energy levels much smaller than the InP bandgap. (paper)

  9. Semiconductor device comprising a pn-heterojunction

    NARCIS (Netherlands)

    2007-01-01

    An electric device is disclosed comprising a pn-heterojunction ( 4 ) formed by a nanowire ( 3 ) of 111 -V semiconductor material and a semiconductor body ( 1 ) comprising a group IV semiconductor material. The nanowire ( 3 ) is positioned in direct contact with the surface ( 2 ) of the semiconductor

  10. Fabrication and Doping Methods for Silicon Nano- and Micropillar Arrays for Solar-Cell Applications: A Review.

    Science.gov (United States)

    Elbersen, Rick; Vijselaar, Wouter; Tiggelaar, Roald M; Gardeniers, Han; Huskens, Jurriaan

    2015-11-18

    Silicon is one of the main components of commercial solar cells and is used in many other solar-light-harvesting devices. The overall efficiency of these devices can be increased by the use of structured surfaces that contain nanometer- to micrometer-sized pillars with radial p/n junctions. High densities of such structures greatly enhance the light-absorbing properties of the device, whereas the 3D p/n junction geometry shortens the diffusion length of minority carriers and diminishes recombination. Due to the vast silicon nano- and microfabrication toolbox that exists nowadays, many versatile methods for the preparation of such highly structured samples are available. Furthermore, the formation of p/n junctions on structured surfaces is possible by a variety of doping techniques, in large part transferred from microelectronic circuit technology. The right choice of doping method, to achieve good control of junction depth and doping level, can contribute to an improvement of the overall efficiency that can be obtained in devices for energy applications. A review of the state-of-the-art of the fabrication and doping of silicon micro and nanopillars is presented here, as well as of the analysis of the properties and geometry of thus-formed 3D-structured p/n junctions. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. New PN Even Balanced Sequences for Spread-Spectrum Systems

    Directory of Open Access Journals (Sweden)

    Inácio JAL

    2005-01-01

    Full Text Available A new class of pseudonoise even balanced (PN-EB binary spreading sequences is derived from existing classical odd-length families of maximum-length sequences, such as those proposed by Gold, by appending or inserting one extra-zero element (chip to the original sequences. The incentive to generate large families of PN-EB spreading sequences is motivated by analyzing the spreading effect of these sequences from a natural sampling point of view. From this analysis a new definition for PG is established, from which it becomes clear that very high processing gains (PGs can be achieved in band-limited direct-sequence spread-spectrum (DSSS applications by using spreading sequences with zero mean, given that certain conditions regarding spectral aliasing are met. To obtain large families of even balanced (i.e., equal number of ones and zeros sequences, two design criteria are proposed, namely the ranging criterion (RC and the generating ranging criterion (GRC. PN-EB sequences in the polynomial range are derived using these criteria, and it is shown that they exhibit secondary autocorrelation and cross-correlation peaks comparable to the sequences they are derived from. The methods proposed not only facilitate the generation of large numbers of new PN-EB spreading sequences required for CDMA applications, but simultaneously offer high processing gains and good despreading characteristics in multiuser SS scenarios with band-limited noise and interference spectra. Simulation results are presented to confirm the respective claims made.

  12. Antireflection coating on InP for semiconductor detectors

    International Nuclear Information System (INIS)

    Hantehzadeh, M.R.; Ghoranneviss, M.; Sari, A.H.; Sahlani, F.; Shokuhi, A.; Shariati, M.

    2006-01-01

    Aluminum nitride thin film by RF magnetron sputtering is used to produce antireflection coating on InP. The index of refection variation of aluminum nitride for different thickness at different wavelength in the range of 400 to 1500 nm is investigated using reflection spectroscopy. Subsequent Ar+ ion implantation at 30 keV with different doses on these coated layers has been performed. The morphology of aluminum nitride after ion implantation is characterized using atomic force microscopy AFM

  13. Antireflection coating on InP for semiconductor detectors

    Energy Technology Data Exchange (ETDEWEB)

    Hantehzadeh, M.R. [Plasma Physics Research Center, Science and Research Campus of Islamic Azad University, Tehran (Iran, Islamic Republic of)]. E-mail: hanteh@sr.iau.ac.ir; Ghoranneviss, M. [Plasma Physics Research Center, Science and Research Campus of Islamic Azad University, Tehran (Iran, Islamic Republic of); Sari, A.H. [Plasma Physics Research Center, Science and Research Campus of Islamic Azad University, Tehran (Iran, Islamic Republic of); Sahlani, F. [Plasma Physics Research Center, Science and Research Campus of Islamic Azad University, Tehran (Iran, Islamic Republic of); Shokuhi, A. [Plasma Physics Research Center, Science and Research Campus of Islamic Azad University, Tehran (Iran, Islamic Republic of); Shariati, M. [Plasma Physics Research Center, Science and Research Campus of Islamic Azad University, Tehran (Iran, Islamic Republic of)

    2006-10-25

    Aluminum nitride thin film by RF magnetron sputtering is used to produce antireflection coating on InP. The index of refection variation of aluminum nitride for different thickness at different wavelength in the range of 400 to 1500 nm is investigated using reflection spectroscopy. Subsequent Ar+ ion implantation at 30 keV with different doses on these coated layers has been performed. The morphology of aluminum nitride after ion implantation is characterized using atomic force microscopy AFM.

  14. Fabrication of InP-pentacene inorganic-organic hybrid heterojunction using MOCVD grown InP for photodetector application

    Science.gov (United States)

    Sarkar, Kalyan Jyoti; Pal, B.; Banerji, P.

    2018-04-01

    We fabricated inorganic-organic hybrid heterojunction between indium phosphide (InP) and pentacene for photodetector application. InP layer was grown on n-Si substrate by atmospheric pressure metal organic chemical vapour deposition (MOCVD) technique. Morphological properties of InP and pentacene thin film were characterized by atomic force microscopy (AFM). Current-voltage characteristics were investigated in dark and under illumination condition at room temperature. During illumination, different wavelengths of visible and infrared light source were employed to perform the electrical measurement. Enhancement of photocurrent was observed with decreasing in wavelength of incident photo radiation. Ideality factor was found to be 1.92. High rectification ratio of 225 was found at ± 3 V in presence of infrared light source. This study provides new insights of inorganic-organic hybrid heterojunction for broadband photoresponse in visible to near infrared (IR) region under low reverse bias condition.

  15. Study of the electroplated of Ni for betavoltaic battery using PN junction without seed layer

    Energy Technology Data Exchange (ETDEWEB)

    Uhm, Young Rang; Kim, Jong Bum; Son, Kwang Jae [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Cho, Byoung Gun [Electronics and Telecommunications Research Institute, Daejeon (Korea, Republic of)

    2015-10-15

    The mechanism of a nuclear battery is same as the P.N junction diode for solar cell application. The photovoltaic is operated by converting photons into electrical energy in the junction. In a betavoltaic battery, beta particles are collected and converted into electrical energy with a similar principle as a photovoltaic. If a radioisotope (RI) with a long half-life (over 100 years) is used, the lifetime of the power source is extended to as long as the half-life time of the RI. Hence, the power sources we describe could extend a system's operating life by several decades or even a century, during which time the system can gain learned behavior without worrying about the power turning off. The beta spectrum of {sup 63}Ni is below the radiation damage threshold (approximately 200 keV for Si) of semiconductors such as Si and SiC. Beta particles of 63Ni were deposited by electroplating on the Ni-foil substrate and attached on the trench P-N absorber with a spacing of 50 μm. The optimum total thickness of the 63Ni layer was determined to be about 2 μm, when regarding the minimum self-shielding effect of the beta-ray (β-ray). The optimum condition of the electroplating {sup 63}Ni was determined at current density of 20 mA/cm{sup 2}.

  16. Study of the electroplated of Ni for betavoltaic battery using PN junction without seed layer

    International Nuclear Information System (INIS)

    Uhm, Young Rang; Kim, Jong Bum; Son, Kwang Jae; Cho, Byoung Gun

    2015-01-01

    The mechanism of a nuclear battery is same as the P.N junction diode for solar cell application. The photovoltaic is operated by converting photons into electrical energy in the junction. In a betavoltaic battery, beta particles are collected and converted into electrical energy with a similar principle as a photovoltaic. If a radioisotope (RI) with a long half-life (over 100 years) is used, the lifetime of the power source is extended to as long as the half-life time of the RI. Hence, the power sources we describe could extend a system's operating life by several decades or even a century, during which time the system can gain learned behavior without worrying about the power turning off. The beta spectrum of 63 Ni is below the radiation damage threshold (approximately 200 keV for Si) of semiconductors such as Si and SiC. Beta particles of 63Ni were deposited by electroplating on the Ni-foil substrate and attached on the trench P-N absorber with a spacing of 50 μm. The optimum total thickness of the 63Ni layer was determined to be about 2 μm, when regarding the minimum self-shielding effect of the beta-ray (β-ray). The optimum condition of the electroplating 63 Ni was determined at current density of 20 mA/cm 2

  17. Unique Three-Dimensional InP Nanopore Arrays for Improved Photoelectrochemical Hydrogen Production.

    Science.gov (United States)

    Li, Qiang; Zheng, Maojun; Ma, Liguo; Zhong, Miao; Zhu, Changqing; Zhang, Bin; Wang, Faze; Song, Jingnan; Ma, Li; Shen, Wenzhong

    2016-08-31

    Ordered three-dimensional (3D) nanostructure arrays hold promise for high-performance energy harvesting and storage devices. Here, we report the fabrication of InP nanopore arrays (NPs) in unique 3D architectures with excellent light trapping characteristic and large surface areas for use as highly active photoelectrodes in photoelectrochemical (PEC) hydrogen evolution devices. The ordered 3D NPs were scalably synthesized by a facile two-step etching process of (1) anodic etching of InP in neutral 3 M NaCl electrolytes to realize nanoporous structures and (2) wet chemical etching in HCl/H3PO4 (volume ratio of 1:3) solutions for removing the remaining top irregular layer. Importantly, we demonstrated that the use of neutral electrolyte of NaCl instead of other solutions, such as HCl, in anodic etching of InP can significantly passivate the surface states of 3D NPs. As a result, the maximum photoconversion efficiency obtained with ∼15.7 μm thick 3D NPs was 0.95%, which was 7.3 and 1.4 times higher than that of planar and 2D NPs. Electrochemical impedance spectroscopy and photoluminescence analyses further clarified that the improved PEC performance was attributed to the enhanced charge transfer across 3D NPs/electrolyte interfaces, the improved charge separation at 3D NPs/electrolyte junction, and the increased PEC active surface areas with our unique 3D NP arrays.

  18. Minority-carrier lifetime in InP as a function of light bias

    Science.gov (United States)

    Yater, Jane A.; Weinberg, I.; Jenkins, Phillip P.; Landis, Geoffrey A.

    1995-01-01

    Minority-carrier lifetime in InP is studied as a function of doping level and laser intensity using time-resolved photoluminescence. A continuous wave diode laser illuminates bulk InP and acts as a light bias, injecting a steady-state concentration of carriers. A 200 ps laser pulse produces a small transient signal on top of the steady-state luminescence, allowing lifetime to be measured directly as a function of incident intensity. For p-InP, lifetime increases with light bias up to a maximum value. Bulk recombination centers are presumably filled to saturation, allowing minority carriers to live longer. The saturation bias scales with dopant concentration for a particular dopant species. As light bias is increased for n-InP, minority-carrier lifetime increases slightly but then decreases, suggesting radiative recombination as a dominant decay mechanism.

  19. Exploring the effective photon management by InP nanoparticles: Broadband light absorption enhancement of InP/In0.53Ga0.47As/InP thin-film photodetectors

    International Nuclear Information System (INIS)

    Fu, Dong; Zhu, Xi; Li, Jian; Xu, Yun; Song, Guofeng; Wei, Xin; Liu, Jietao

    2015-01-01

    High-index dielectric and semiconductor nanoparticles with the characteristics of low absorption loss and strong scattering have attracted more and more attention for improving performance of thin-film photovoltaic devices. In this paper, we focus our attention on InP nanoparticles and study the influence of the substrate and the geometrical configurations on their scattering properties. We demonstrate that, compared with the InP sphere, the InP cylinder has higher coupling efficiency due to the stronger interactions between the optical mode in the nanoparticle and its induced mirror image in the substrate. Moreover, we propose novel thin-film InGaAs photodetectors integrated with the periodically arranged InP nanoparticles on the substrate. Broadband light absorption enhancement is achieved over the wavelength range between 1.0 μm and 1.7 μm. The highest average absorption enhancement of 59.7% is realized for the photodetector with the optimized cylinder InP nanoparticles. These outstanding characteristics attribute to the preferentially forward scattering of single InP nanoparticle along with the effective coupling of incident light into the guided modes through the collective diffraction effect of InP nanoparticles array

  20. Array of titanium dioxide nanostructures for solar energy utilization

    Science.gov (United States)

    Qiu, Xiaofeng; Parans Paranthaman, Mariappan; Chi, Miaofang; Ivanov, Ilia N; Zhang, Zhenyu

    2014-12-30

    An array of titanium dioxide nanostructures for solar energy utilization includes a plurality of nanotubes, each nanotube including an outer layer coaxial with an inner layer, where the inner layer comprises p-type titanium dioxide and the outer layer comprises n-type titanium dioxide. An interface between the inner layer and the outer layer defines a p-n junction.

  1. Crystallinity, Surface Morphology, and Photoelectrochemical Effects in Conical InP and InN Nanowires Grown on Silicon.

    Science.gov (United States)

    Parameshwaran, Vijay; Xu, Xiaoqing; Clemens, Bruce

    2016-08-24

    The growth conditions of two types of indium-based III-V nanowires, InP and InN, are tailored such that instead of yielding conventional wire-type morphologies, single-crystal conical structures are formed with an enlarged diameter either near the base or near the tip. By using indium droplets as a growth catalyst, combined with an excess indium supply during growth, "ice cream cone" type structures are formed with a nanowire "cone" and an indium-based "ice cream" droplet on top for both InP and InN. Surface polycrystallinity and annihilation of the catalyst tip of the conical InP nanowires are observed when the indium supply is turned off during the growth process. This growth design technique is extended to create single-crystal InN nanowires with the same morphology. Conical InN nanowires with an enlarged base are obtained through the use of an excess combined Au-In growth catalyst. Electrochemical studies of the InP nanowires on silicon demonstrate a reduction photocurrent as a proof of photovolatic behavior and provide insight as to how the observed surface polycrystallinity and the resulting interface affect these device-level properties. Additionally, a photovoltage is induced in both types of conical InN nanowires on silicon, which is not replicated in epitaxial InN thin films.

  2. X-ray structure amplitudes for GaAs and InP

    International Nuclear Information System (INIS)

    Pietsch, U.

    1985-01-01

    The structure amplitudes of GaAs and InP are calculated taking into account the nonspherical parts of the valence electron density by means of a static bond charge model. The best known temperature factors and dispersion coefficients are employed. The calculated structure amplitudes should help determining exactly the shape of X-ray diffraction patterns. (author)

  3. High-speed carrier-depletion silicon Mach-Zehnder optical modulators with lateral PN junctions

    Directory of Open Access Journals (Sweden)

    Graham Trevor Reed

    2014-12-01

    Full Text Available This paper presents new experimental data from a lateral PN junction silicon Mach-Zehnder optical modulator. Efficiencies in the 1.4V.cm to 1.9V.cm range are demonstrated for drive voltages between 0V and 6V. High speed operation up to 52Gbit/s is also presented. The performance of the device which has its PN junction positioned in the centre of the waveguide is then compared to previously reported data from a lateral PN junction device with the junction self-aligned to the edge of the waveguide rib. An improvement in modulation efficiency is demonstrated when the junction is positioned in the centre of the waveguide. Finally we propose schemes for achieving high modulation efficiency whilst retaining self-aligned formation of the PN junction.

  4. Switching characteristics of an InP photonic crystal nanocavity: Experiment and theory

    DEFF Research Database (Denmark)

    Yu, Yi; Palushani, Evarist; Heuck, Mikkel

    2013-01-01

    The dynamical properties of an InP photonic crystal nanocavity are experimentally investigated using pump-probe techniques and compared to simulations based on coupled-mode theory. Excellent agreement between experimental results and simulations is obtained when employing a rate equation model...

  5. The effect of phosphorus and sulfur treatment on the surface properties of InP

    Science.gov (United States)

    Iyer, R.; Chang, R. R.; Dubey, A.; Lile, D. L.

    1988-01-01

    Experimental results are presented for InP surfaces treated by using red phosphorus as a source to create an excess overpressure of phosphorus during annealing and prior to silicon dioxide deposition. The surface has been probed by in situ photoluminescence, noncontacting remote gate C-V, and conventional high-frequency and quasi-static C-V methods. A study has also been made of the surface of sulfurized InP following heating in aqueous (NH4)2S(x). MISFETs fabricated using the benefits of these surface treatments show high transconductances and stabilities approaching those of thermal SiO2/Si with less than 5-percent variation in drain current over a 12-hr period.

  6. Formation and characterization of Ni nanostructures in porous InP - from crystallites to wires

    International Nuclear Information System (INIS)

    Gerngross, M.-D.; Hrkac, V.; Kienle, L.; Carstensen, J.; Foell, H.

    2013-01-01

    In this work the galvanic formation of Ni crystallites and Ni nanowires with very high aspect ratios (>1000:1) in porous InP is presented. By depositing a dielectric interlayer on the InP pore walls it is possible to produce very high aspect ratio Ni nanowires. The coercivity of these nanowires is about 100 Oe (in-plane) and 240 Oe (out-of-plane), while the coercivity of the crystallites lies in between these values. The in-plane remanence squareness of the Ni nanowires is very low (S ∼ 0.08), out-of-plane it is 0.36. For the Ni crystallites the remanence squareness lies in between the range given for the Ni nanowires. (author)

  7. Synthesis and properties of ultra-long InP nanowires on glass.

    Science.gov (United States)

    Dhaka, Veer; Pale, Ville; Khayrudinov, Vladislav; Kakko, Joona-Pekko; Haggren, Tuomas; Jiang, Hua; Kauppinen, Esko; Lipsanen, Harri

    2016-12-16

    We report on the synthesis of Au-catalyzed InP nanowires (NWs) on low-cost glass substrates. Ultra-dense and ultra-long (up to ∼250 μm) InP NWs, with an exceptionally high growth rate of ∼25 μm min -1 , were grown directly on glass using metal organic vapor phase epitaxy (MOVPE). Structural properties of InP NWs grown on glass were similar to the ones grown typically on Si substrates showing many structural twin faults but the NWs on glass always exhibited a stronger photoluminescence (PL) intensity at room temperature. The PL measurements of NWs grown on glass reveal two additional prominent impurity related emission peaks at low temperature (10 K). In particular, the strongest unusual emission peak with an activation energy of 23.8 ± 2 meV was observed at 928 nm. Different possibilities including the role of native defects (phosphorus and/or indium vacancies) are discussed but most likely the origin of this PL peak is related to the impurity incorporation from the glass substrate. Furthermore, despite the presence of suspected impurities, the NWs on glass show outstanding light absorption in a wide spectral range (60%-95% for λ = 300-1600 nm). The optical properties and the NW growth mechanism on glass is discussed qualitatively. We attribute the exceptionally high growth rate mostly to the atmospheric pressure growth conditions of our MOVPE reactor and stronger PL intensity on glass due to the impurity doping. Overall, the III-V NWs grown on glass are similar to the ones grown on semiconductor substrates but offer additional advantages such as low-cost and light transparency.

  8. Physicochemical Characterization and Skin Permeation of Cationic Transfersomes Containing the Synthetic Peptide PnPP-19.

    Science.gov (United States)

    Almeida, Flavia De Marco; Silva, Carolina Nunes; de Araujo Lopes, Savia Caldeira; Santos, Daniel Moreira; Torres, Fernanda Silva; Cardoso, Felipe Lima; Martinelli, Patricia Massara; da Silva, Elizabeth Ribeiro; de Lima, Maria Elena; Miranda, Lucas Antonio Ferreira; Oliveira, Monica Cristina

    2018-01-08

    PnPP-19 is a 19-amino-acid synthetic peptide previously described as a novel drug for the treatment of erectile dysfunction. The aim of this work was to evaluate the physicochemical properties of cationic transfersomes containing PnPP-19 and the skin permeation of free PnPP-19 and PnPP-19-loaded transfersomes. Three different liposomal preparation methods were evaluated. Cationic transfersomes contained egg phosphatidyl choline: stearylamine (9:1 w/w) and Tween 20 (84.6:15.4 lipid:Tween, w/w). Lipid concentration varied from 20 to 40 mM. We evaluated the entrapment percentage, mean diameter, zeta potential and stability at 4 oC of the formulations. The skin permeation assays were performed with abdominal human skin using Franz diffusion cell with 3 cm2 diffusion area at 32 oC and a fluorescent derivative of the peptide, containing 5-TAMRA, bound to PnPP-19 C-terminal region, where an extra lysine was inserted. Our results showed variable entrapment efficiencies, from 6% to 30%, depending on the preparation method and the lipid concentration used. The reverse phase evaporation method using a total lipid concentration equal to 40 mM led to the best entrapment percentage (30.2 + 4.5%). Free PnPP-19 was able to permeate skin at a rate of 10.8 ng/cm2/h. However, PnPP-19 was specifically hydrolyzed by skin proteases, generating a fragment of 15 amino acid residues. Encapsulated PnPP-19 permeated the skin at a rate of 19.8 ng/cm2/h. The encapsulation of PnPP-19 in cationic transfersomes protected the peptide from degradation, favoring its topical administration. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

  9. A positron annihilation study of compensation defects responsible for conduction-type conversions in LEC-grown InP

    International Nuclear Information System (INIS)

    Shan, Y.Y.; Ling, C.C.; Fung, S.; Beling, C.D.; Zhao, Y.W.

    2001-01-01

    Positron annihilation techniques have been employed to investigate the formation of vacancy type of compensation defects in undoped LEC-grown InP. N-type InP becomes p-type semiconducting by short time annealing at 700 C, and then turns to be n-type again after further annealing but with a much higher resistivity. Positron lifetime measurements show that the positron average lifetime τ av increases to a high value of 247ps for the first n-type to p-type conversion and decreases to 240ps for the following p-type to n-type conversion. τ av increases slightly and saturates at 242ps upon further annealing. The results of positron annihilation Doppler-broadening measurements are consistent with the positron lifetime measurements. The correlation between the characteristics of positron annihilation and the conversions of conduction type indicates that the formation of vacancy type defects and the progressive variation of their concentrations during annealing are critical to the electrical properties of the bulk InP material. (orig.)

  10. Effect of sulphur-doping on the formation of deep centers in n-type InP under irradiation

    International Nuclear Information System (INIS)

    Kol'chenko, T.I.; Lomako, V.M.; Moroz, S.E.

    1988-01-01

    Effect of sulfur-doping on the efficiency of electron trap formation in InP under irradiation was studied using deep level capacity nonstationary spectroscopy method (DLCNS). Structures with Schottky barrier based on epitaxial InP films with ∼10μm thickness (n 0 =8x10 14 -6x10 17 cm -3 ) were irradiated with 60 Co γ-quanta at 40 deg C; the particle flux intensity made up ∼10 12 cm -2 xs -1 . Experimental results presented allow one to conclude that InP doping with sulfur up to n 0 =6x10 17 cm -3 in contrast to the case of silicon doping does not produce a notable effect on the electron trap formation efficiency under irradiation. The observed reduction of configuration-bistable M-center introduction rate in samples with n 0 >10 16 cm -3 is explained by the change of filling of E c -0.12 eV level belonging to unknown X defect

  11. Self-Catalyzed Growth and Characterization of In(As)P Nanowires on InP(111)B Using Metal-Organic Chemical Vapor Deposition.

    Science.gov (United States)

    Park, Jeung Hun; Pozuelo, Marta; Setiawan, Bunga P D; Chung, Choong-Heui

    2016-12-01

    We report the growth of vertical -oriented InAs x P1-x (0.11 ≤ x ≤ 0.27) nanowires via metal-organic chemical vapor deposition in the presence of indium droplets as catalysts on InP(111)B substrates at 375 °C. Trimethylindium, tertiarybutylphosphine, and tertiarybutylarsine are used as the precursors, corresponding to P/In and As/In molar ratios of 29 and 0.01, respectively. The as-grown nanowire growth morphologies, crystallinity, composition, and optical characteristics are determined using a combination of scanning and transmission electron microscopies, electron diffraction, and X-ray photoelectron, energy dispersive X-ray, and Raman spectroscopies. We find that the InAs x P1-x nanowires are tapered with narrow tops, wider bases, and In-rich In-As alloy tips, characteristic of vapor-liquid-solid process. The wires exhibit a mixture of zinc blende and wurtzite crystal structures and a high density of structural defects such as stacking faults and twins. Our results suggest that the incorporation of As into InP wires decreases with increasing substrate temperature. The Raman spectra obtained from the In(As)P nanowires reveal a red-shift and lower intensity of longitudinal optical mode relative to both InP nanowires and InP(111)B bulk, due to the incorporation of As into the InP matrix.

  12. Photoluminescence properties of ZnO films grown on InP by thermally oxidizing metallic Zn films

    CERN Document Server

    Chen, S J; Zhang, J Y; Lu, Y M; Shen, D Z; Fan, X W

    2003-01-01

    Photoluminescence (PL) properties of ZnO films grown on (001) InP substrates by thermal oxidization of metallic Zn films, in which oxygen vacancies and interstitial Zn ions are compensated by P ions diffusing from (001) InP substrates, are investigated. X-ray diffraction spectra indicate that P ions have diffused into the Zn films and chemically combined with Zn ions to form Zn sub 3 P sub 2. Intense free exciton emission dominates the PL spectra of ZnO films with very weak deep-level emission. Low-temperature PL spectra at 79 K are dominated by neutral-donor bound exciton emission at 3.299 eV (I sub 4) with a linewidth of 17.3 meV and neutral-acceptor bound exciton emission at 3.264 eV. The free exciton emission increases with increasing temperature and eventually dominates the emission spectrum for temperature higher than 170 K. Furthermore, the visible emission around 2.3 eV correlated with oxygen deficiencies and interstitial Zn defects was quenched to a remarkable degree by P diffusing from InP substrate...

  13. Selective Epitaxy of InP on Si and Rectification in Graphene/InP/Si Hybrid Structure.

    Science.gov (United States)

    Niu, Gang; Capellini, Giovanni; Hatami, Fariba; Di Bartolomeo, Antonio; Niermann, Tore; Hussein, Emad Hameed; Schubert, Markus Andreas; Krause, Hans-Michael; Zaumseil, Peter; Skibitzki, Oliver; Lupina, Grzegorz; Masselink, William Ted; Lehmann, Michael; Xie, Ya-Hong; Schroeder, Thomas

    2016-10-12

    The epitaxial integration of highly heterogeneous material systems with silicon (Si) is a central topic in (opto-)electronics owing to device applications. InP could open new avenues for the realization of novel devices such as high-mobility transistors in next-generation CMOS or efficient lasers in Si photonics circuitry. However, the InP/Si heteroepitaxy is highly challenging due to the lattice (∼8%), thermal expansion mismatch (∼84%), and the different lattice symmetries. Here, we demonstrate the growth of InP nanocrystals showing high structural quality and excellent optoelectronic properties on Si. Our CMOS-compatible innovative approach exploits the selective epitaxy of InP nanocrystals on Si nanometric seeds obtained by the opening of lattice-arranged Si nanotips embedded in a SiO 2 matrix. A graphene/InP/Si-tip heterostructure was realized on obtained materials, revealing rectifying behavior and promising photodetection. This work presents a significant advance toward the monolithic integration of graphene/III-V based hybrid devices onto the mainstream Si technology platform.

  14. Photoluminescence properties of ZnO films grown on InP by thermally oxidizing metallic Zn films

    International Nuclear Information System (INIS)

    Chen, S J; Liu, Y C; Zhang, J Y; Lu, Y M; Shen, D Z; Fan, X W

    2003-01-01

    Photoluminescence (PL) properties of ZnO films grown on (001) InP substrates by thermal oxidization of metallic Zn films, in which oxygen vacancies and interstitial Zn ions are compensated by P ions diffusing from (001) InP substrates, are investigated. X-ray diffraction spectra indicate that P ions have diffused into the Zn films and chemically combined with Zn ions to form Zn 3 P 2 . Intense free exciton emission dominates the PL spectra of ZnO films with very weak deep-level emission. Low-temperature PL spectra at 79 K are dominated by neutral-donor bound exciton emission at 3.299 eV (I 4 ) with a linewidth of 17.3 meV and neutral-acceptor bound exciton emission at 3.264 eV. The free exciton emission increases with increasing temperature and eventually dominates the emission spectrum for temperature higher than 170 K. Furthermore, the visible emission around 2.3 eV correlated with oxygen deficiencies and interstitial Zn defects was quenched to a remarkable degree by P diffusing from InP substrates

  15. Effects of multiple substitution upon the P...N noncovalent interaction

    International Nuclear Information System (INIS)

    Scheiner, Steve

    2011-01-01

    Graphical abstract: The presence of one halogen opposite the N results in strong attraction between P and N. This force is little affected by identity of Y atoms, whether H or halogen. Highlights: → Strong attractive force directly between trivalent P and N atoms. → P...N force is unlike H-bonds or halogen bonds, but stronger than both. → Multiple halogenation beyond a single atom on P slightly weakens the interaction. - Abstract: The attractive noncovalent interaction of a P atom with N is derived primarily from two sources. Charge transfer from the N lone pair into the σ * antibonding orbital of a P-X bond that is turned away from the N atom combines with attractive Coulombic forces. As in the case of H-bonding, which is parallel in some ways to P...N attraction, placement of an electron-withdrawing substituent on the P atom enhances both of these components, and strengthens the overall interaction. However, in stark contrast with H-bonding, halogenation beyond monosubstitution does not lead to any further strengthening of the P...N noncovalent bond. Indeed, di and tri-substitution lead to small reductions in the interaction energy. In all cases, the geometry which contains a P...N bond is more stable than other candidate structures, some of which contain hydrogen or halogen bonds.

  16. Unraveling aminophosphine redox mechanisms for glovebox-free InP quantum dot syntheses.

    Science.gov (United States)

    Laufersky, Geoffry; Bradley, Siobhan; Frécaut, Elian; Lein, Matthias; Nann, Thomas

    2018-05-10

    The synthesis of colloidal indium phosphide quantum dots (InP QDs) has always been plagued by difficulties arising from limited P3- sources. Being effectively restricted to the highly pyrophoric tris(trimethylsilyl) phosphine (TMS3P) creates complications for the average chemist and presents a significant risk for industrially scaled reactions. The adaptation of tris(dialkylamino) phosphines for these syntheses has garnered attention, as these new phosphines are much safer and can generate nanoparticles with competitive photoluminescence properties to those from (TMS)3P routes. Until now, the reaction mechanics of this precursor were elusive due to many experimental optimizations, such as the inclusion of a high concentration of zinc salts, being atypical of previous InP syntheses. Herein, we utilize density functional theory calculations to outline a logical reaction mechanism. The aminophosphine precursor is found to require activation by a zinc halide before undergoing a disproportionation reaction to self-reduce this P(iii) material to a P(-iii) source. We use this understanding to adapt this precursor for a two-pot nanoparticle synthesis in a noncoordinating solvent outside of glovebox conditions. This allowed us to generate spherical InP/ZnS nanoparticles possessing fluorescence quantum yields >55% and lifetimes as fast as 48 ns, with tunable emission according to varying zinc halide acidity. The development of high quality and efficient InP QDs with this safer aminophosphine in simple Schlenk environments will enable a broader range of researchers to synthesize these nontoxic materials for a variety of high-value applications.

  17. Diffusion length variation and proton damage coefficients for InP/In(x)Ga(1-x)As/GaAs solar cells

    Science.gov (United States)

    Jain, R. K.; Weinberg, I.; Flood, D. J.

    1993-01-01

    Indium phosphide solar cells are more radiation resistant than gallium arsenide and silicon solar cells, and their growth by heteroepitaxy offers additional advantages leading to the development of lighter, mechanically strong and cost-effective cells. Changes in heteroepitaxial InP cell efficiency under 0.5 and 3 MeV proton irradiations are explained by the variation in the minority-carrier diffusion length. The base diffusion length versus proton fluence is calculated by simulating the cell performance. The diffusion length damage coefficient K(L) is plotted as a function of proton fluence.

  18. Pn-waves Travel-time Anomaly beneath Taiwan from Dense Seismic Array Observations and its Possible Tectonic Implications

    Science.gov (United States)

    Lin, Y. Y.; Huang, B. S.; Ma, K. F.; Hsieh, M. C.

    2015-12-01

    We investigated travel times of Pn waves, which are of great important for understanding the Moho structure in Taiwan region. Although several high quality tomographic studies had been carried out, observations of Pn waves are still the most comprehensive way to elucidate the Moho structure. Mapping the Moho structure of Taiwan had been a challenging due to the small spatial dimension of Taiwan island with two subduction systems. To decipher the tectonic structure and understanding of earthquake hazard, the island of Taiwan have been implemented by several high density seismic stations, including 71 short-period stations of Central Weather Bureau Seismic Network (CWBSN) and 42 broardband stations of Broadband Array in Taiwan for Seismology (BATS). High quality seismic records of these stations would be used to identify precise Pn-wave arrival times. After station-elevation correction, we measure the difference between the observed and theoretical Pn arrivals from the IASPI 91 model for each station. For correcting uncertainties of earthquake location and origin time, we estimate relative Pn anomaly, ΔtPn , between each station and a reference station. The pattern of ΔtPn reflects the depth anomaly of Moho beneath Taiwan. In general, Pn waves are commonly observed from shallow earthquake at epicentral distance larger than 120 km. We search the global catalog since 2005 and the criteria are M > 5.5, focal depth 150 km. The 12 medium earthquakes from north Luzon are considered for analysis. We choose a station, TWKB, in the most southern point of Taiwan as the reference station due to that all events are from the south. The results indicate obvious different patterns of ΔtPn from different back-azimuths. The ΔtPn pattern of the events in the first group from the south south-east indicates that the Pn arrivals delay suddenly when the Pn waves pass through the Central Range, suggesting the Moho becomes deep rapidly. However, we cannot recognize the same pattern when

  19. The etching of InP in HCl solutions : a chemical mechanism

    NARCIS (Netherlands)

    Notten, P.H.L.

    1984-01-01

    The etch rate of InP in solutions of high HCl concentration was shown to be independent of the applied potential ina wide potential range negative with respect to the flatband value. Dissolution of the solid led to the formation of PH3.The etch rate, which was not mass-transport controlled, was

  20. Electrical/thermal transport and electronic structure of the binary cobalt pnictides CoPn2 (Pn = As and Sb

    Directory of Open Access Journals (Sweden)

    Yosuke Goto

    2015-06-01

    Full Text Available We demonstrate the electrical and thermal transport properties of polycrystalline CoPn2 (Pn = As and Sb between 300 and 900 K. CoAs2 shows semiconducting electrical transport up to 900 K, while CoSb2 exhibits degenerate conduction. Sign inversion of the Seebeck coefficient is observed at ∼310 and ∼400 K for CoAs2 and CoSb2, respectively. Thermal conductivity at 300 K is 11.7 Wm−1K−1 for CoAs2 and 9.4 Wm−1K−1 for CoSb2. The thermoelectric power factor of CoAs2 is ∼10 μWcm−1K−2, although the dimensionless figure of merit is limited to ∼0.1 due to relatively high thermal conductivity. Using electronic structure calculations, the band gap value is calculated to be 0.55 eV for CoAs2 and 0.26 eV for CoSb2.

  1. Electrical and thermal characterization of single and multi-finger InP DHBTs

    DEFF Research Database (Denmark)

    Midili, Virginio; Nodjiadjim, V.; Johansen, Tom Keinicke

    2015-01-01

    This paper presents the characterization of single and multi-finger Indium Phosphide Double Heterojunction Bipolar transistors (InP DHBTs). It is used as the starting point for technology optimization. Safe Operating Area (SOA) and small signal AC parameters are investigated along with thermal ch...

  2. Potential high efficiency solar cells: Applications from space photovoltaic research

    Science.gov (United States)

    Flood, D. J.

    1986-01-01

    NASA involvement in photovoltaic energy conversion research development and applications spans over two decades of continuous progress. Solar cell research and development programs conducted by the Lewis Research Center's Photovoltaic Branch have produced a sound technology base not only for the space program, but for terrestrial applications as well. The fundamental goals which have guided the NASA photovoltaic program are to improve the efficiency and lifetime, and to reduce the mass and cost of photovoltaic energy conversion devices and arrays for use in space. The major efforts in the current Lewis program are on high efficiency, single crystal GaAs planar and concentrator cells, radiation hard InP cells, and superlattice solar cells. A brief historical perspective of accomplishments in high efficiency space solar cells will be given, and current work in all of the above categories will be described. The applicability of space cell research and technology to terrestrial photovoltaics will be discussed.

  3. Formation of quantum wires and dots on InP(001) by As/P exchange

    International Nuclear Information System (INIS)

    Yang, Haeyeon; Ballet, P.; Salamo, G. J.

    2001-01-01

    We report on the use of in situ scanning tunneling microscopy to study As/P exchange on InP(001) surfaces by molecular beam epitaxy. Results demonstrate that the exchange process can be controlled to selectively produce either quantum wires or quantum dots. 15 nm wide self-assembled nanowires are observed, and they are elongated along the dimer row direction of the InP(001)-2x4 surface with a length of over 1 μm and flat top 2x4 surfaces. In addition, when the nanowires are annealed with no arsenic overpressure, the surface reconstruction transforms from 2x4 to 4x2 and the nanowires transform into dots with a rectangular base and flat top. [copyright] 2001 American Institute of Physics

  4. Atomic-scaled characterization of graphene PN junctions

    Science.gov (United States)

    Zhou, Xiaodong; Wang, Dennis; Dadgar, Ali; Agnihotri, Pratik; Lee, Ji Ung; Reuter, Mark C.; Ross, Frances M.; Pasupathy, Abhay N.

    Graphene p-n junctions are essential devices for studying relativistic Klein tunneling and the Veselago lensing effect in graphene. We have successfully fabricated graphene p-n junctions using both lithographically pre-patterned substrates and the stacking of vertical heterostructures. We then use our 4-probe STM system to characterize the junctions. The ability to carry out scanning electron microscopy (SEM) in our STM instrument is essential for us to locate and measure the junction interface. We obtain both the topography and dI/dV spectra at the junction area, from which we track the shift of the graphene chemical potential with position across the junction interface. This allows us to directly measure the spatial width and roughness of the junction and its potential barrier height. We will compare the junction properties of devices fabricated by the aforementioned two methods and discuss their effects on the performance as a Veselago lens.

  5. On P2 ⋄ Pn -supermagic labeling of edge corona product of cycle and path graph

    Science.gov (United States)

    Yulianto, R.; Martini, Titin S.

    2018-04-01

    A simple graph G = (V, E) admits a H-covering, where H is subgraph of G, if every edge in E belongs to a subgraph of G isomorphic to H. Graph G is H-magic if there is a total labeling f:V(G)\\cup E(G)\\to 1,2,\\ldots,|V(G)|+|E(G)|, such that each subgraph {H}{\\prime }=({V}{\\prime },{E}{\\prime }) of G isomorphic to H and satisfying f{({H}{\\prime })}=def{\\sum }\\upsilon \\in {V{\\prime }}f(\\upsilon )+{\\sum }e\\in {E{\\prime }}f(e)=m(f) where m(f) is a constant magic sum. Additionaly, G admits H-supermagic if f(V)=1,2,\\ldots,|V|. The edge corona {C}n \\diamond {P}n of Cn and Pn is defined as the graph obtained by taking one copy of Cn and n copies of Pn , and then joining two end-vertices of the i-th edge of Cn to every vertex in the i-th copy of Pn . This research aim is to find H-supermagic covering on an edge corona product of cycle and path graph {C}n \\diamond {P}n where H is {P}2 \\diamond {P}n. We use k-balanced multiset to solve our reserarch. Here, we find that an edge corona product of cycle and path graph {C}n \\diamond {P}n is {P}2 \\diamond {P}n supermagic for n > 3.

  6. Control of morphology and crystal purity of InP nanowires by variation of phosphine flux during selective area MOMBE

    Science.gov (United States)

    Kelrich, A.; Dubrovskii, V. G.; Calahorra, Y.; Cohen, S.; Ritter, D.

    2015-02-01

    We present experimental results showing how the growth rate, morphology and crystal structure of Au-catalyzed InP nanowires (NWs) fabricated by selective area metal organic molecular beam epitaxy can be tuned by the growth parameters: temperature and phosphine flux. The InP NWs with 20-65 nm diameters are grown at temperatures of 420 and 480 °C with the PH3 flow varying from 1 to 9 sccm. The NW tapering is suppressed at a higher temperature, while pure wurtzite crystal structure is preferred at higher phosphine flows. Therefore, by combining high temperature and high phosphine flux, we are able to fabricate non-tapered and stacking fault-free InP NWs with the quality that other methods rarely achieve. We also develop a model for NW growth and crystal structure which explains fairly well the observed experimental tendencies.

  7. Effects of surface states on device and interconnect isolation in GaAs MESFET and InP MISFET integrated circuits

    International Nuclear Information System (INIS)

    Hasegawa, H.; Kitagawa, T.; Masuda, H.; Yano, H.; Ohno, H.

    1985-01-01

    Surface electrical breakdown and side-gating which cause failure of device and interconnect isolation are investigated for GaAs MESFET and InP MISFET integrated circuit structures. Striking differences in behavior are observed between GaAs and InP as regards to the surface conduction, surface breakdown and side-gating. These differences are shown to be related to the surface state properties of the insulator-semiconductor interface. In GaAs, high density of surface states rather than bulk trap states control the surface I-V characteristics and side-gating, causing serious premature avalanche breakdown and triggering side-gating at a low nominal field intensity of 1-3 kV/cm. On the other hand, InP MISFET integrated circuits are virtually free from these premature breakdown and side-gating effect under normal dark operating condition because of very low surface state density

  8. The Horizontal Ice Nucleation Chamber (HINC): INP measurements at conditions relevant for mixed-phase clouds at the High Altitude Research Station Jungfraujoch

    Science.gov (United States)

    Lacher, Larissa; Lohmann, Ulrike; Boose, Yvonne; Zipori, Assaf; Herrmann, Erik; Bukowiecki, Nicolas; Steinbacher, Martin; Kanji, Zamin A.

    2017-12-01

    In this work we describe the Horizontal Ice Nucleation Chamber (HINC) as a new instrument to measure ambient ice-nucleating particle (INP) concentrations for conditions relevant to mixed-phase clouds. Laboratory verification and validation experiments confirm the accuracy of the thermodynamic conditions of temperature (T) and relative humidity (RH) in HINC with uncertainties in T of ±0.4 K and in RH with respect to water (RHw) of ±1.5 %, which translates into an uncertainty in RH with respect to ice (RHi) of ±3.0 % at T > 235 K. For further validation of HINC as a field instrument, two measurement campaigns were conducted in winters 2015 and 2016 at the High Altitude Research Station Jungfraujoch (JFJ; Switzerland, 3580 m a. s. l. ) to sample ambient INPs. During winters 2015 and 2016 the site encountered free-tropospheric conditions 92 and 79 % of the time, respectively. We measured INP concentrations at 242 K at water-subsaturated conditions (RHw = 94 %), relevant for the formation of ice clouds, and in the water-supersaturated regime (RHw = 104 %) to represent ice formation occurring under mixed-phase cloud conditions. In winters 2015 and 2016 the median INP concentrations at RHw = 94 % was below the minimum detectable concentration. At RHw = 104 %, INP concentrations were an order of magnitude higher, with median concentrations in winter 2015 of 2.8 per standard liter (std L-1; normalized to standard T of 273 K and pressure, p, of 1013 hPa) and 4.7 std L-1 in winter 2016. The measurements are in agreement with previous winter measurements obtained with the Portable Ice Nucleation Chamber (PINC) of 2.2 std L-1 at the same location. During winter 2015, two events caused the INP concentrations at RHw = 104 % to significantly increase above the campaign average. First, an increase to 72.1 std L-1 was measured during an event influenced by marine air, arriving at the JFJ from the North Sea and the Norwegian Sea. The contribution from anthropogenic or other

  9. Magnetic electron focusing and tuning of the electron current with a pn-junction

    Energy Technology Data Exchange (ETDEWEB)

    Milovanović, S. P., E-mail: slavisa.milovanovic@uantwerpen.be; Ramezani Masir, M., E-mail: mrmphys@gmail.com; Peeters, F. M., E-mail: francois.peeters@uantwerpen.be [Departement Fysica, Universiteit Antwerpen, Groenenborgerlaan 171, B-2020 Antwerpen (Belgium)

    2014-01-28

    Transverse magnetic focusing properties of graphene using a ballistic four terminal structure are investigated. The electric response is obtained using the semiclassical billiard model. The transmission exhibits pronounced peaks as a consequence of skipping orbits at the edge of the structure. When we add a pn-junction between the two probes, snake states along the pn-interface appear. Injected electrons are guided by the pn-interface to one of the leads depending on the value of the applied magnetic field. Oscillations in the resistance are found depending on the amount of particles that end up in each lead.

  10. Effect of uniaxial stress on free and bismuth-bound excitons in InP

    International Nuclear Information System (INIS)

    Weber, G.; Ruehle, W.

    1979-01-01

    The reduction of the shear deformation potentials of holes bound to the isoelectronic impurity Bi in InP is determined by piezoluminescence. It is compared with the corresponding reduction for holes bound to the Coulomb-type acceptors C and Zn. The theory for an effective mass acceptor describes well the cases of C and Zn. However, additional effects as local strain and Stark fields must be involved in the case of Bi leading to an extremely large reduction of the deformation potentials. No change in binding energy with applied stress as well as no exchange splitting of the Bi-bound exciton can be detected within experimental accuracy. The stress dependence of the free exciton reflectance reveals values for the band deformation potentials and a value of 0.07 meV for the exchange splitting of the free exciton in InP. (author)

  11. Direct observation of the carrier transport process in InGaN quantum wells with a pn-junction

    Science.gov (United States)

    Wu, Haiyan; Ma, Ziguang; Jiang, Yang; Wang, Lu; Yang, Haojun; Li, Yangfeng; Zuo, Peng; Jia, Haiqiang; Wang, Wenxin; Zhou, Junming; Liu, Wuming; Chen, Hong

    2016-11-01

    A new mechanism of light-to-electricity conversion that uses InGaN/GaN QWs with a p-n junction is reported. According to the well established light-to-electricity conversion theory, quantum wells (QWs) cannot be used in solar cells and photodetectors because the photogenerated carriers in QWs usually relax to ground energy levels, owing to quantum confinement, and cannot form a photocurrent. We observe directly that more than 95% of the photoexcited carriers escape from InGaN/GaN QWs to generate a photocurrent, indicating that the thermionic emission and tunneling processes proposed previously cannot explain carriers escaping from QWs. We show that photoexcited carriers can escape directly from the QWs when the device is under working conditions. Our finding challenges the current theory and demonstrates a new prospect for developing highly efficient solar cells and photodetectors. Project supported by the National Natural Science Foundation of China (Grant Nos. 11574362, 61210014, and 11374340) and the Innovative Clean-energy Research and Application Program of Beijing Municipal Science and Technology Commission, China (Grant No. Z151100003515001).

  12. Impact of P/In flux ratio and epilayer thickness on faceting for nanoscale selective area growth of InP by molecular beam epitaxy.

    Science.gov (United States)

    Fahed, M; Desplanque, L; Coinon, C; Troadec, D; Wallart, X

    2015-07-24

    The impact of the P/In flux ratio and the deposited thickness on the faceting of InP nanostructures selectively grown by molecular beam epitaxy (MBE) is reported. Homoepitaxial growth of InP is performed inside 200 nm wide stripe openings oriented either along a [110] or [1-10] azimuth in a 10 nm thick SiO2 film deposited on an InP(001) substrate. When varying the P/In flux ratio, no major shape differences are observed for [1-10]-oriented apertures. On the other hand, the InP nanostructure cross sections strongly evolve for [110]-oriented apertures for which (111)B facets are more prominent and (001) ones shrink for large P/In flux ratio values. These results show that the growth conditions allow tailoring the nanocrystal shape. They are discussed in the framework of the equilibrium crystal shape model using existing theoretical calculations of the surface energies of different low-index InP surfaces as a function of the phosphorus chemical potential, directly related to the P/In ratio. Experimental observations strongly suggest that the relative (111)A surface energy is probably smaller than the calculated value. We also discuss the evolution of the nanostructure shape with the InP-deposited thickness.

  13. Fabrication of Affordable and Sustainable Solar Cells Using NiO/TiO2 P-N Heterojunction

    Directory of Open Access Journals (Sweden)

    Kingsley O. Ukoba

    2018-01-01

    Full Text Available The need for affordable, clean, efficient, and sustainable solar cells informed this study. Metal oxide TiO2/NiO heterojunction solar cells were fabricated using the spray pyrolysis technique. The optoelectronic properties of the heterojunction were determined. The fabricated solar cells exhibit a short-circuit current of 16.8 mA, open-circuit voltage of 350 mV, fill factor of 0.39, and conversion efficiency of 2.30% under 100 mW/cm2 illumination. This study will help advance the course for the development of low-cost, environmentally friendly, and sustainable solar cell materials from metal oxides.

  14. Study of discharge in quiescent plasma machine of the INPE

    International Nuclear Information System (INIS)

    Ferreira, J.G.; Ferreira, J.L.; Ludwig, G.O.; Maciel, H.S.

    1988-12-01

    Measurements of principal plasma parameters produced by quiescent plasma machine of the Instituto de Pesquisas Espaciais (INPE) for current of 500 mA and several values of pressure and discharge power are presented. A qualitative interpretation for obtained results is done and a simple model for plasma density is compared with experimental values. The conditions of cathode operation are also investigated. (M.C.K.)

  15. Phosphine synthetic route features and postsynthetic treatment of InP quantum dots

    International Nuclear Information System (INIS)

    Mordvinova, Natalia; Vinokurov, Alexander; Dorofeev, Sergey; Kuznetsova, Tatiana; Znamenkov, Konstantin

    2014-01-01

    Highlights: • Quantum dots with average diameter of 3–5 nm were synthesized. • PH 3 was used as novel phosphorous precursor. • Electrophoresis was demonstrated to be an effective method of purification of QDs. • Photoeching leads to quantum yields about 20%. • The concentration and time dependencies for photoetching of QDs were obtained. -- Abstract: In this paper we report on the development of synthesis of InP quantum dots with a gaseous phosphine PH 3 as a source of phosphorus and myristic acid and TOP/TOPO as stabilizers. Samples synthesized using myristic acid as stabilizer at relatively low temperatures were found to contain admixture of In(OH) 3 . We studied the influence of HF concentration and duration of illumination on luminescence properties of InP quantum dots during photoetching process. Quantum yields of photoetched samples reached about 20%. Additionally, electrophoresis as a new technique of purification and size-depended separation of synthesized quantum dots was developed

  16. Effect of reactor neutron radiation and temperature on the structure of InP single crystals

    International Nuclear Information System (INIS)

    Bojko, V.M.; Kolin, N.G.; Merkurisov, D.I.; Bublik, V.T.; Voronova, M.I.; Shcherbachev, K.D.

    2006-01-01

    The structural characteristics of InP single crystals have been investigated depending on the radiation effects produced by fast and full spectrum neutrons and subsequent heat treatment. A lattice period in InP single crystals decreases under neutron irradiation. Fast neutrons make the main contribution into the change of the lattice period. Availability of the thermal neutrons initiates the formation of Sn atoms, but does not make a significant influence on the change of the lattice period. Heat treatment of the irradiated samples up to 600 deg C causes the annealing of radiation defects and recovery of the lattice period. With increasing neutron fluences a lattice period becomes even higher than before irradiation [ru

  17. Nondestructive evaluation of differently doped InP wafers by time-resolved four-wave mixing technique

    International Nuclear Information System (INIS)

    Kadys, A.; Sudzius, M.; Jarasiunas, K.; Mao Luhong; Sun Niefeng

    2006-01-01

    Photoelectric properties of semi-insulating, differently doped, and undoped indium phosphide wafers, grown by the liquid encapsulation Czochralski method, have been investigated by time-resolved picosecond four-wave mixing technique. Deep defect related carrier generation, recombination, and transport properties were investigated experimentally by measuring four-wave mixing kinetics and exposure characteristics. The presence of deep donor states in undoped InP was confirmed by a pronounced effect of a space charge electric field to carrier transport. On the other hand, the recharging dynamics of electrically active residual impurities was observed in undoped and Fe-doped InP through the process of efficient trapping of excess carriers. The bipolar diffusion coefficients and mobilities were determined for the all wafers

  18. Polarization transfer in (p,n) reactions at 495 MeV

    International Nuclear Information System (INIS)

    Taddeucci, T.N.

    1991-01-01

    Polarization transfer observables have been measured with the NTOF facility at LAMPF for (p,n) reactions at 495 MeV. Measurements of the longitudinal polarization transfer parameter D LL for transitions to discrete states at 0 degrees show convincing evidence for tensor interaction effects. Complete sets of polarization transfer observables have been measured for quasifree (p,n) reactions on 2 H, 12 C, 40 Ca at a scattering angle of 18 degrees. These measurements show no evidence for an enhancement in the isovector spin longitudinal response. 19 refs., 10 figs

  19. Three-dimensional Ag2O/Bi5O7I p-n heterojunction photocatalyst harnessing UV-vis-NIR broad spectrum for photodegradation of organic pollutants.

    Science.gov (United States)

    Chen, Yannan; Zhu, Gangqiang; Hojamberdiev, Mirabbos; Gao, Jianzhi; Zhu, Runliang; Wang, Chenghui; Wei, Xiumei; Liu, Peng

    2018-02-15

    Ag 2 O nanoparticles-loaded Bi 5 O 7 I microspheres forming a three dimensional Ag 2 O/Bi 5 O 7 I p-n heterojunction photocatalyst with wide-spectrum response were synthesized in this study. The results of transmission electron microscopy observations revealed that the Ag 2 O nanoparticles with the diameter of ca. 10-20nm were distributed on the surfaces of Bi 5 O 7 I nanosheets. The as-synthesized Ag 2 O/Bi 5 O 7 I exhibited an excellent wide-spectrum response to wavelengths ranging from ultraviolet (UV) to near-infrared (NIR), indicating its potential for effective utilization of solar energy. Compared with pure Bi 5 O 7 I, the Ag 2 O/Bi 5 O 7 I composite also demonstrated excellent photocatalytic activity for the degradation of Bisphenol A and phenol in aqueous solution under visible LED light irradiation. Among samples, the 20% Ag 2 O/Bi 5 O 7 I composite photocatalyst showed the highest photocatalytic activity for the degradation of Bisphenol A and phenol in aqueous solution. In addition, the 20% Ag 2 O/Bi 5 O 7 I composite also exhibited a photocatalytic activity for the degradation of Bisphenol A under NIR light irradiation. The improved photocatalytic activity is attributed to the formation of a p-n heterojunction between Ag 2 O and Bi 5 O 7 I, allowing the efficient utilization of solar energy (from UV to NIR) and high separation efficiency of photogenerated electron-hole pairs. The present work is desirable to explore a possible avenue for the full utilization of solar energy. Copyright © 2017 Elsevier B.V. All rights reserved.

  20. High temperature annealing of minority carrier traps in irradiated MOCVD n(+)p InP solar cell junctions

    Science.gov (United States)

    Messenger, S. R.; Walters, R. J.; Summers, G. P.

    1993-01-01

    Deep level transient spectroscopy was used to monitor thermal annealing of trapping centers in electron irradiated n(+)p InP junctions grown by metalorganic chemical vapor deposition, at temperatures ranging from 500 up to 650K. Special emphasis is given to the behavior of the minority carrier (electron) traps EA (0.24 eV), EC (0.12 eV), and ED (0.31 eV) which have received considerably less attention than the majority carrier (hole) traps H3, H4, and H5, although this work does extend the annealing behavior of the hole traps to higher temperatures than previously reported. It is found that H5 begins to anneal above 500K and is completely removed by 630K. The electron traps begin to anneal above 540K and are reduced to about half intensity by 630K. Although they each have slightly different annealing temperatures, EA, EC, and ED are all removed by 650K. A new hole trap called H3'(0.33 eV) grows as the other traps anneal and is the only trap remaining at 650K. This annealing behavior is much different than that reported for diffused junctions.

  1. Defect formation in n-type InP at elevated temperatures of irradiation

    International Nuclear Information System (INIS)

    Kozlovskij, V.V.; Kol'chenko, T.I.; Lomako, V.M.; Moroz, S.E.

    1990-01-01

    Effect of irradiation temperature within 25-250 deg C traps in InP. Rate of most deep level introduction, as well as, rate of charge carrier removing at the increase of irradiation temperature are shown to decrease and it is explained by defect annealing occuring simultaneously with irradiation

  2. AES, EELS and TRIM simulation method study of InP(100 subjected to Ar+, He+ and H+ ions bombardment.

    Directory of Open Access Journals (Sweden)

    Abidri B.

    2012-06-01

    Full Text Available Auger Electron Spectroscopy (AES and Electron Energy Loss Spectroscopy (EELS have been performed in order to investigate the InP(100 surface subjected to ions bombardment. The InP(100 surface is always contaminated by carbon and oxygen revealed by C-KLL and O-KLL AES spectra recorded just after introduction of the sample in the UHV spectrometer chamber. The usually cleaning process of the surface is the bombardment by argon ions. However, even at low energy of ions beam (300 eV indium clusters and phosphorus vacancies are usually formed on the surface. The aim of our study is to compare the behaviour of the surface when submitted to He+ or H+ ions bombardment. The helium ions accelerated at 500V voltage and for 45 mn allow removing contaminants but induces damaged and no stoichiometric surface. The proton ions were accelerated at low energy of 500 eV to bombard the InP surface at room temperature. The proton ions broke the In-P chemical bonds to induce the formation of In metal islands. Such a chemical reactivity between hydrogen and phosphorus led to form chemical species such as PH and PH3, which desorbed from the surface. The chemical susceptibly and the small size of H+ advantaged their diffusion into bulk. Since the experimental methods alone were not able to give us with accuracy the disturbed depth of the target by these ions. We associate to the AES and EELS spectroscopies, the TRIM (Transport and Range of Ions in Matter simulation method in order to show the mechanism of interaction between Ar+, He+ or H+ ions and InP and determine the disturbed depth of the target by argon, helium or proton ions.

  3. Study of seed layer effect in nuclear battery with P-N diode junction

    Energy Technology Data Exchange (ETDEWEB)

    Uhm, Young Rang; Son, Kwang Jae; Lee, Jun Sig [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Choi, Byoung Gun [Kookmin Univ., Seoul (Korea, Republic of)

    2014-10-15

    A nuclear battery with diode junction is a device that converts nuclear radiation directly to electric power. The mechanism of a nuclear battery is same as the P-N junction diode for solar cell application. The photovoltaic is operated by converted photons to electrical energy in the junction. In betavoltaic battery, beta particles are collected and converted to electrical energy as similar principle as photovoltaic. A very low current, order of nano or micro amps, is generated in devices. If a radioisotope (RI) with a long halflife (over 50 years) is used, a lifetime of a power source is extended as long as halflife time of RI.. Some special applications require long-lived compact power sources. These include space equipment, sensors in remote locations (space, underground, etc.), and implantable medical devices. Conventionally, these sources rely on converting chemical energy to electricity. This means they require a large storage of chemical 'fuel' since the amount of energy released per reaction is small. The nuclear battery is a novel solution to solve the power needs of these applications. For the {sup 63}Ni beta-source we used, the half-life is 100.2 years. Hence, the power sources we describe could extend a system's operating life by several decades or even a century, during which time the system could gain learned behavior without worrying about the power turning off. Radioactive thin-film-based power sources also have energy density orders of magnitude higher than chemical-reaction-based energy sources. In this study, we fabricate nuclear battery using {sup 63}Ni source with diode junction, and studied seed layer effect for optimization of structure of p-n junction.

  4. Structural and electronic properties of zigzag InP nanoribbons with Stone–Wales type defects

    International Nuclear Information System (INIS)

    Longo, R C; Carrete, J; Varela, L M; Gallego, L J

    2016-01-01

    By means of density-functional-theoretic calculations, we investigate the structural and electronic properties of a hexagonal InP sheet and of hydrogen-passivated zigzag InP nanoribbons (ZInPNRs) with Stone–Wales (SW)-type defects. Our results show that the influence of this kind of defect is not limited to the defected region but it leads to the formation of ripples that extend across the systems, in keeping with the results obtained recently for graphene and silicene sheets. The presence of SW defects in ZInPNRs causes an appreciable broadening of the band gap and transforms the indirect-bandgap perfect ZInPNR into a direct-bandgap semiconductor. An external transverse electric field, regardless of its direction, reduces the gap in both the perfect and defective ZInPNRs. (paper)

  5. Highly doped InP as a low loss plasmonic material for mid-IR region

    DEFF Research Database (Denmark)

    Panah, Mohammad Esmail Aryaee; Takayama, Osamu; Morozov, S. V.

    2016-01-01

    by fitting the calculated infrared reflectance spectra to the measured ones. The retrieved permittivity was then used to simulate surface plasmon polaritons (SPPs) propagation on flat and structured surfaces, and the simulation results were verified in direct experiments. SPPs at the top and bottom......We study plasmonic properties of highly doped InP in the mid-infrared (IR) range. InP was grown by metal-organic vapor phase epitaxy (MOVPE) with the growth conditions optimized to achieve high free electron concentrations by doping with silicon. The permittivity of the grown material was found...... interfaces of the grown epilayer were excited by the prism coupling. A high-index Ge hemispherical prism provides efficient coupling conditions of SPPs on flat surfaces and facilitates acquiring their dispersion diagrams. We observed diffraction into symmetry-prohibited diffraction orders stimulated...

  6. Systematics in p-n interaction vs deformation

    International Nuclear Information System (INIS)

    Singh, M.; Singh, Yuvraj; Kumar, Rajesh; Vrshney, A.K.; Gupta, K.K.

    2017-01-01

    The correlation of integrated valance p-n interaction in the onset of collectivity and deformation has been described phenomenologically in terms of N p N n scheme. L. Esser et al. presented the graphs between N p N n and deformation β and γ for some heavy nuclei

  7. Modeling of InP HBTs in Transferred-Substrate Technology for Millimeter-Wave Applications

    DEFF Research Database (Denmark)

    Johansen, Tom Keinicke; Rudolph, Matthias; Jensen, Thomas

    2013-01-01

    In this paper, the modeling of InP heterojunction bipolar transistors (HBTs) in transferred substrate (TS) technology is investigated. At first, a direct parameter extraction methodology dedicated to III-V based HBTs is employed to determine the small-signal equivalent circuit parameters from...

  8. Small- and large-signal modeling of InP HBTs in transferred-substrate technology

    DEFF Research Database (Denmark)

    Johansen, Tom Keinicke; Rudolph, Matthias; Jensen, Thomas

    2014-01-01

    In this paper, the small- and large-signal modeling of InP heterojunction bipolar transistors (HBTs) in transferred substrate (TS) technology is investigated. The small-signal equivalent circuit parameters for TS-HBTs in two-terminal and three-terminal configurations are determined by employing...

  9. Characterization of vertical GaN p-n diodes and junction field-effect transistors on bulk GaN down to cryogenic temperatures

    Science.gov (United States)

    Kizilyalli, I. C.; Aktas, O.

    2015-12-01

    There is great interest in wide-bandgap semiconductor devices and most recently in vertical GaN structures for power electronic applications such as power supplies, solar inverters and motor drives. In this paper the temperature-dependent electrical behavior of vertical GaN p-n diodes and vertical junction field-effect transistors fabricated on bulk GaN substrates of low defect density (104 to 106 cm-2) is described. Homoepitaxial MOCVD growth of GaN on its native substrate and the ability to control the doping in the drift layers in GaN have allowed the realization of vertical device architectures with drift layer thicknesses of 6 to 40 μm and net carrier electron concentrations as low as 1 × 1015 cm-3. This parameter range is suitable for applications requiring breakdown voltages of 1.2 kV to 5 kV. Mg, which is used as a p-type dopant in GaN, is a relatively deep acceptor (E A ≈ 0.18 eV) and susceptible to freeze-out at temperatures below 200 K. The loss of holes in p-GaN has a deleterious effect on p-n junction behavior, p-GaN contacts and channel control in junction field-effect transistors at temperatures below 200 K. Impact ionization-based avalanche breakdown (BV > 1200 V) in GaN p-n junctions is characterized between 77 K and 423 K for the first time. At higher temperatures the p-n junction breakdown voltage improves due to increased phonon scattering. A positive temperature coefficient in the breakdown voltage is demonstrated down to 77 K; however, the device breakdown characteristics are not as abrupt at temperatures below 200 K. On the other hand, contact resistance to p-GaN is reduced dramatically above room temperature, improving the overall device performance in GaN p-n diodes in all cases except where the n-type drift region resistance dominates the total forward resistance. In this case, the electron mobility can be deconvolved and is found to decrease with T -3/2, consistent with a phonon scattering model. Also, normally-on vertical junction

  10. An InP HBT sub-harmonic mixer for E-band wireless communication

    DEFF Research Database (Denmark)

    Johansen, Tom Keinicke; Krozer, Viktor

    2010-01-01

    This paper reports on a novel balanced HBT subharmonic mixer (SHM) for E-band wireless communication. An LO spiral type Marchand balun is integrated with the SHM. The SHM has been fabricated in a InP double heterojunction bipolar transistor (DHBT) circuit-oriented technology with fT /fmax = 180GHz...

  11. Measurement of third-order nonlinear susceptibility tensor in InP using extended Z-scan technique with elliptical polarization

    Science.gov (United States)

    Oishi, Masaki; Shinozaki, Tomohisa; Hara, Hikaru; Yamamoto, Kazunuki; Matsusue, Toshio; Bando, Hiroyuki

    2018-05-01

    The elliptical polarization dependence of the two-photon absorption coefficient β in InP has been measured by the extended Z-scan technique for thick materials in the wavelength range from 1640 to 1800 nm. The analytical formula of the Z-scan technique has been extended with consideration of multiple reflections. The Z-scan results have been fitted very well by the formula and β has been evaluated accurately. The three independent elements of the third-order nonlinear susceptibility tensor in InP have also been determined accurately from the elliptical polarization dependence of β.

  12. Constraining Phosphorus Chemistry in Carbon- and Oxygen-Rich Circumstellar Envelopes: Observations of PN, HCP, and CP

    Science.gov (United States)

    Milam, S. N.; Halfen, D. T.; Tenenbaum, E. D.; Apponi, A. J.; Woolf, N. J.; Ziurys, L. M.

    2008-09-01

    Millimeter-wave observations of PN, CP, and HCP have been carried out toward circumstellar envelopes of evolved stars using the Arizona Radio Observatory (ARO). HCP and PN have been identified in the carbon-rich source CRL 2688 via observations at 1 mm using the Submillimeter Telescope (SMT) and 2-3 mm with the Kitt Peak 12 m. An identical set of measurements were carried out toward IRC +10216, as well as observations of CP at 1 mm. PN was also observed toward VY Canis Majoris (VY CMa), an oxygen-rich supergiant star. The PN and HCP line profiles in CRL 2688 and IRC +10216 are roughly flat topped, indicating unresolved, optically thin emission; CP, in contrast, has a distinct "U" shape in IRC +10216. Modeling of the line profiles suggests abundances, relative to H2, of f(PN) ~ (3-5) × 10-9 and f(HCP) ~ 2 × 10-7 in CRL 2688, about an order of magnitude higher than in IRC +10216. In VY CMa, f(PN) is ~4 × 10-8. The data in CRL 2688 and IRC +10216 are consistent with LTE formation of HCP and PN in the inner envelope, as predicted by theoretical calculations, with CP a photodissociation product at larger radii. The observed abundance of PN in VY CMa is a factor of 100 higher than LTE predictions. In IRC +10216, the chemistry of HCP/CP mimics that of HCN/CN and suggests an N2 abundance of f ~ 1 × 10-7. The chemistry of phosphorus appears active in both carbon- and oxygen-rich envelopes of evolved stars.

  13. Use of Advanced Solar Cells for Commercial Communication Satellites

    Science.gov (United States)

    Bailey, Sheila G.; Landis, Geoffrey A.

    1995-01-01

    The current generation of communications satellites are located primarily in geosynchronous Earth orbit (GEO). Over the next decade, however, a new generation of communications satellites will be built and launched, designed to provide a world-wide interconnection of portable telephones. For this mission, the satellites must be positioned in lower polar and near-polar orbits. To provide complete coverage, large numbers of satellites will be required. Because the required number of satellites decreases as the orbital altitude is increased, fewer satellites would be required if the orbit chosen were raised from low to intermediate orbit. However, in intermediate orbits, satellites encounter significant radiation due to trapped electrons and protons. Radiation tolerant solar cells may be necessary to make such satellites feasible. We analyze the amount of radiation encountered in low and intermediate polar orbits at altitudes of interest to next-generation communication satellites, calculate the expected degradation for silicon, GaAs, and InP solar cells, and show that the lifetimes can be significantly increased by use of advanced solar cells.

  14. The Horizontal Ice Nucleation Chamber (HINC: INP measurements at conditions relevant for mixed-phase clouds at the High Altitude Research Station Jungfraujoch

    Directory of Open Access Journals (Sweden)

    L. Lacher

    2017-12-01

    Full Text Available In this work we describe the Horizontal Ice Nucleation Chamber (HINC as a new instrument to measure ambient ice-nucleating particle (INP concentrations for conditions relevant to mixed-phase clouds. Laboratory verification and validation experiments confirm the accuracy of the thermodynamic conditions of temperature (T and relative humidity (RH in HINC with uncertainties in T of ±0.4 K and in RH with respect to water (RHw of ±1.5 %, which translates into an uncertainty in RH with respect to ice (RHi of ±3.0 % at T > 235 K. For further validation of HINC as a field instrument, two measurement campaigns were conducted in winters 2015 and 2016 at the High Altitude Research Station Jungfraujoch (JFJ; Switzerland, 3580 m a. s. l.  to sample ambient INPs. During winters 2015 and 2016 the site encountered free-tropospheric conditions 92 and 79 % of the time, respectively. We measured INP concentrations at 242 K at water-subsaturated conditions (RHw = 94 %, relevant for the formation of ice clouds, and in the water-supersaturated regime (RHw = 104 % to represent ice formation occurring under mixed-phase cloud conditions. In winters 2015 and 2016 the median INP concentrations at RHw = 94 % was below the minimum detectable concentration. At RHw = 104 %, INP concentrations were an order of magnitude higher, with median concentrations in winter 2015 of 2.8 per standard liter (std L−1; normalized to standard T of 273 K and pressure, p, of 1013 hPa and 4.7 std L−1 in winter 2016. The measurements are in agreement with previous winter measurements obtained with the Portable Ice Nucleation Chamber (PINC of 2.2 std L−1 at the same location. During winter 2015, two events caused the INP concentrations at RHw = 104 % to significantly increase above the campaign average. First, an increase to 72.1 std L−1 was measured during an event influenced by marine air, arriving at the JFJ

  15. The Oklahoma PN/ADN Articulation Project Report.

    Science.gov (United States)

    Oklahoma State Regents for Higher Education, Oklahoma City.

    In response to a critical nursing shortage in the state of Oklahoma, the Oklahoma Practical Nursing (PN)/Associate Degree Nursing (ADN) Articulation Project Coordinating Committee was formed in spring 1990 to develop a proposal for program articulation. A curriculum matrix was designed and adopted for use by five regional subcommittees which…

  16. Changes in structure of the short-range order of the InP melt when heated

    International Nuclear Information System (INIS)

    Glazov, V.M.; Dovletov, K.; Nashel'skij, A.Ya.; Mamedov, M.M.

    1977-01-01

    An investigation of the temperature dependence of the InP viscosity has indicated an ''after-melting'' effect similar to that observed in other A 3 V 5 compounds having a sphalerite structure. The termodynamic parameters of the viscous flow of indium phosphide melt have been calculated, and a suggestion has been made on the loosening of the short-range order structure of the melt during the period preceding solidification. With the similarity in the behaviour of InP and of A 3 Sb compound melts as a basis, a suggestion has been put forward that the influence of the thermal dissociation upon the character of the changes in the short-range order structure directly after transition from the solid to the liquid phase is negligible

  17. Valence-band splitting energies in wurtzite InP nanowires: Photoluminescence spectroscopy and ab initio calculations

    Science.gov (United States)

    Gadret, E. G.; Dias, G. O.; Dacal, L. C. O.; de Lima, M. M., Jr.; Ruffo, C. V. R. S.; Iikawa, F.; Brasil, M. J. S. P.; Chiaramonte, T.; Cotta, M. A.; Tizei, L. H. G.; Ugarte, D.; Cantarero, A.

    2010-09-01

    We investigated experimentally and theoretically the valence-band structure of wurtzite InP nanowires. The wurtzite phase, which usually is not stable for III-V phosphide compounds, has been observed in InP nanowires. We present results on the electronic properties of these nanowires using the photoluminescence excitation technique. Spectra from an ensemble of nanowires show three clear absorption edges separated by 44 meV and 143 meV, respectively. The band edges are attributed to excitonic absorptions involving three distinct valence-bands labeled: A, B, and C. Theoretical results based on “ab initio” calculation gives corresponding valence-band energy separations of 50 meV and 200 meV, respectively, which are in good agreement with the experimental results.

  18. New connecting elements for cascade photoelectric converters based on InP

    Science.gov (United States)

    Marichev, A. E.; Pushnyi, B. V.; Levin, R. V.; Lebedeva, N. M.; Prasolov, N. D.; Kontrosh, E. V.

    2018-03-01

    In this paper, we report on the initial studies of connecting elements for cascade photodetectors. The heterostructures used in this work are based on InP. As a connecting element, it is proposed to use nanocrystalline inclusions instead of the tunnel junction. GaP nanocrystals are most suitable for this purpose because this material does not cause absorption of the incident radiation.

  19. New Pn and Sn tomographic images of the uppermost mantle beneath the Mediterranean region

    Science.gov (United States)

    Gil, A.; Díaz, J.; Gallart, J.

    2012-04-01

    We present here new images of the seismic velocity and anisotropy variations in the uppermost mantle beneath the Mediterranean region, compiled from inversion of Pn and Sn phases. The method of Hearn (1996) has been applied to Pn and Sn lectures from the catalogs of the International Seismological Center and the Spanish Instituto Geografico Nacional. A total of 1,172,293 Pn arrivals coming from 16,527 earthquakes recorded at 1,657 stations with epicentral distances between 220 km and 1400 km have been retained (331,567 arrivals from 15,487events at 961 stations for Sn). Our results, grossly consistent with available 3D tomography images, show significant features well correlated with surface geology. The Pn velocities are high (>8.2 km/s) beneath major sedimentary basins (western Alboran Sea, Valencia Trough, Adriatic Sea, Aquitaine, Guadalquivir, Rharb, Aquitaine and Po basins), and low (Islands, probably related to a thermal anomaly associated to the westward displacement of the Alboran block along the Emile Baudot escarpment 16 Ma ago. The Pn anisotropic image shows consistent orientations sub-parallel to major orogenic structures, such as Betics, Apennines, Calabrian Arc and Alps. The station delays beneath Betic and Rif ranges are strongly negative, suggesting the presence of crustal thickening all along the Gibraltar Arc. However, only the Betics have a very strong low-velocity anomaly and a pronounced anisotropy pattern. The Sn tomographic image correlates well with the Pn image, even if some relevant differences can be observed beneath particular regions.

  20. Experimental studies of thin films deposition by magnetron sputtering method for CIGS solar cell fabrication

    Science.gov (United States)

    Gułkowski, Sławomir; Krawczak, Ewelina

    2017-10-01

    Among a variety of the thin film solar cell technologies of second generation, copper-indium-gallium-diselenide device (CIGS) with the latest highest lab cell efficiency record of 22.4 % seems to be the most promising for the power generation. This is partly due to the advantages of using low cost films of few microns thick not only as a metallic contacts but also as a main structure of the solar cell consisted of high quality semiconductor layers. This paper reports the experimental studies of the CIGS absorber formation on Soda Lime Glass substrate covered by thin molybdenum film as a back contact layer. All structures were deposited with the use of magnetron sputtering method only. Technological parameters of the deposition process such as deposition power, pressure and deposition time were optimized for each layer of the structure. Mo back contact was examined in terms of resistivity. EDS measurements were carried out to verify stoichiometric composition of CIGS absorber. Thin film of Al was used as a top contact in order to examine the quality of p-n junction. The I-V electrical characteristic of the p-n junction was analysed in terms of solar cell application.

  1. Velocity auto-correlation and hot-electron diffusion constant in GaAs and InP

    International Nuclear Information System (INIS)

    Deb Roy, M.

    1982-01-01

    Auto-correlation functions of the fluctuations in the electron velocities transverse and parallel to the applied electric field are calculated by the Monte Carlo method for GaAs and InP at three different values of field strength which are around three times the threshold field for negative differential mobility in each case. From these the frequency-dependent diffusion coefficients transverse and parallel to the applied field and the figure of merit for noise performance when used in a microwave amplifying device are determined. The results indicate that the transverse auto-correlation function Csub(t)(s) falls nearly exponentially to zero with increasing interval s while the parallel function Csub(p)(s) falls sharply, attains a minimum and then rises towards zero. In each case a higher field gives a higher rate of fall and makes the correlation functions zero within a shorter interval. The transverses diffusion coefficient falls monotonically with the frequency but the parallel diffusion coefficient generally starts with a low value at low frequencies, rises to a maximum and then falls. InP, with a larger separation between the central and the satellite valleys, has a higher value of the low frequency transverse diffusion coefficient and a lower value of its parallel counterpart. The noise performance of microwave semiconductor amplifying devices depends mainly on the low frequency parallel diffusion constant and consequently devices made out of materials like InP with a large separation between valleys are likely to have better noise characteristics. (orig.)

  2. Molecular beam epitaxial growth and characterization of zinc-blende ZnMgSe on InP (001)

    International Nuclear Information System (INIS)

    Sohel, Mohammad; Munoz, Martin; Tamargo, Maria C.

    2004-01-01

    High crystalline quality zinc-blende structure Zn (1-x) Mg x Se epitaxial layers were grown on InP (001) substrates by molecular beam epitaxy. Their band gap energies were determined as a function of Mg concentration and a linear dependence was observed. The band gap of the Zn (1-x) Mg x Se closely lattice matched to InP was found to be 3.59 eV at 77 K and the extrapolated value for zinc-blende MgSe was determined to be 3.74 eV. Quantum wells of Zn (1-x) Cd x Se with Zn (1-x) Mg x Se as the barrier layer were grown which exhibit near ultraviolet emission

  3. Valley detection using a graphene gradual pn junction with spin–orbit coupling: An analytical conductance calculation

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Mou, E-mail: yang.mou@hotmail.com [Guangdong Provincial Key Laboratory of Quantum Engineering and Quantum Materials, School of Physics and Telecommunication Engineering, South China Normal University, Guangzhou 510006 (China); Wang, Rui-Qiang [Guangdong Provincial Key Laboratory of Quantum Engineering and Quantum Materials, School of Physics and Telecommunication Engineering, South China Normal University, Guangzhou 510006 (China); Bai, Yan-Kui [College of Physical Science and Information Engineering and Hebei Advance Thin Films Laboratory, Hebei Normal University, Shijiazhuang, Hebei 050024 (China)

    2015-09-04

    Graphene pn junction is the brick to build up variety of graphene nano-structures. The analytical formula of the conductance of graphene gradual pn junctions in the whole bipolar region has been absent up to now. In this paper, we analytically calculated that pn conductance with the spin–orbit coupling and stagger potential taken into account. Our analytical expression indicates that the energy gap causes the conductance to drop a constant value with respect to that without gap in a certain parameter region, and manifests that the curve of the conductance versus the stagger potential consists of two Gaussian peaks – one valley contributes one peak. The latter feature allows one to detect the valley polarization without using double-interface resonant devices. - Highlights: • Analytical conductance formula of the gradual graphene pn junction with spin–orbit coupling in the whole bipolar region. • Exploring the valley-dependent transport of gradual graphene pn junctions analytically. • Conductance peak without resonance.

  4. 19th Scientific Readings Devoted to P.N. Chirvinskiy

    Directory of Open Access Journals (Sweden)

    I. Ya. Ilaltdinov

    2017-03-01

    Full Text Available Scientific conference devoted to P.N. Chirvinskiy was held in the Perm State University (January 2017. The problems of mineralogy, petrology, lithology, metallogeny and geochemistry were discussed.

  5. Electronic properties of GaAs, InAs and InP nanowires studied by terahertz spectroscopy

    International Nuclear Information System (INIS)

    Joyce, Hannah J; Docherty, Callum J; Lloyd-Hughes, James; Herz, Laura M; Johnston, Michael B; Gao Qiang; Tan, H Hoe; Jagadish, Chennupati

    2013-01-01

    We have performed a comparative study of ultrafast charge carrier dynamics in a range of III–V nanowires using optical pump–terahertz probe spectroscopy. This versatile technique allows measurement of important parameters for device applications, including carrier lifetimes, surface recombination velocities, carrier mobilities and donor doping levels. GaAs, InAs and InP nanowires of varying diameters were measured. For all samples, the electronic response was dominated by a pronounced surface plasmon mode. Of the three nanowire materials, InAs nanowires exhibited the highest electron mobilities of 6000 cm 2 V −1 s −1 , which highlights their potential for high mobility applications, such as field effect transistors. InP nanowires exhibited the longest carrier lifetimes and the lowest surface recombination velocity of 170 cm s −1 . This very low surface recombination velocity makes InP nanowires suitable for applications where carrier lifetime is crucial, such as in photovoltaics. In contrast, the carrier lifetimes in GaAs nanowires were extremely short, of the order of picoseconds, due to the high surface recombination velocity, which was measured as 5.4 × 10 5   cm s −1 . These findings will assist in the choice of nanowires for different applications, and identify the challenges in producing nanowires suitable for future electronic and optoelectronic devices. (paper)

  6. INP studies for a Tau-Charm Factory

    International Nuclear Information System (INIS)

    Skrinsky, A.

    1994-01-01

    This paper presents the results of studies undertaken at INP of options for a Tau Charm Factory. Three different beam options have been studied. First is a 'round beam option', allowing axially symmetric beams which yield high tau-pair productivity. The second option involves monochromatic beams, which enhances productivity for narrow c bar c states, gives good tau pair productions in a clean manner, and has a good resonant-to-nonresonant ratio. The third option allows longitudinal polarization, should it prove to be interesting. It is an easy option to implement because it only involves polarized electrons. Work on some of these options is described in terms of experiments on the VEPP-2 device

  7. InP based lasers and optical amplifiers with wire-/dot-like active regions

    DEFF Research Database (Denmark)

    Reithmaier, J. P.; Somers, A.; Deubert, S.

    2005-01-01

    Long wavelength lasers and semiconductor optical amplifiers based on InAs quantum wire/dot-like active regions were developed on InP substrates dedicated to cover the extended telecommunication wavelength range between 1.4 - 1.65 mm. In a brief overview different technological approaches will be ...

  8. InP MMIC Chip Set for Power Sources Covering 80-170 GHz

    Science.gov (United States)

    Ngo, Catherine

    2001-01-01

    We will present a Monolithic Millimeter-wave Integrated Circuit (MMIC) chip set which provides high output-power sources for driving diode frequency multipliers into the terahertz range. The chip set was fabricated at HRL Laboratories using a 0.1-micrometer gate-length InAlAs/InGaAs/InP high electron mobility transistor (HEMT) process, and features transistors with an f(sub max) above 600 GHz. The HRL InP HEMT process has already demonstrated amplifiers in the 60-200 GHz range. In this paper, these high frequency HEMTs form the basis for power sources up to 170 GHz. A number of state-of-the-art InP HEMT MMICs will be presented. These include voltage-controlled and fixed-tuned oscillators, power amplifiers, and an active doubler. We will first discuss an 80 GHz voltage-controlled oscillator with 5 GHz of tunability and at least 17 mW of output power, as well as a 120 GHz oscillator providing 7 mW of output power. In addition, we will present results of a power amplifier which covers the full WRIO waveguide band (75-110 GHz), and provides 40-50 mW of output power. Furthermore, we will present an active doubler at 164 GHz providing 8% bandwidth, 3 mW of output power, and an unprecedented 2 dB of conversion loss for an InP HEMT MMIC at this frequency. Finally, we will demonstrate a power amplifier to cover 140-170 GHz with 15-25 mW of output power and 8 dB gain. These components can form a power source in the 155-165 GHz range by cascading the 80 GHz oscillator, W-band power amplifier, 164 GHz active doubler and final 140-170 GHz power amplifier for a stable, compact local oscillator subsystem, which could be used for atmospheric science or astrophysics radiometers.

  9. Transport properties of monolayer and bilayer graphene p-n junctions with charge puddles in the quantum Hall regime

    International Nuclear Information System (INIS)

    Cheng Shuguang

    2010-01-01

    Recent experiments have confirmed that the electron-hole inhomogeneity in graphene is a new type of charge disorder. Motivated by such confirmation, we theoretically study the transport properties of a monolayer graphene (MLG) based p-n junction and a bilayer graphene (BLG) p-n junction in the quantum Hall regime where electron-hole puddles are considered. By using the non-equilibrium Green function method, both the current and conductance are obtained. We find that, in the presence of the electron-hole inhomogeneity, the lowest quantized conductance plateau at e 2 /h emerges in the MLG p-n junction under very small charge puddle disorder strength. For a BLG p-n junction, however, the conductance in the p-n region is enhanced with charge puddles, and the lowest quantized conductance plateau emerges at 2e 2 /h. Besides, when an ideal quantized conductance plateau is formed for a MLG p-n junction, the universal conductance fluctuation is found to be 2e 2 /3h. Furthermore, we also investigate the influence of Anderson disorder on such p-n junctions and the comparison and discussion are given accordingly. To compare the two models with different types of disorder, we investigate the conductance distribution specially. Finally the influence of disorder strength on the conductance of a MLG p-n junction is investigated.

  10. Hydrogen bonding interactions in PN...HX complexes: DFT and ab initio studies of structure, properties and topology.

    Science.gov (United States)

    Varadwaj, Pradeep Risikrishna

    2010-05-01

    Spin-restricted DFT (X3LYP and B3LYP) and ab initio (MP2(fc) and CCSD(fc)) calculations in conjunction with the Aug-CC-pVDZ and Aug-CC-pVTZ basis sets were performed on a series of hydrogen bonded complexes PN...HX (X = F, Cl, Br) to examine the variations of their equilibrium gas phase structures, energetic stabilities, electronic properties, and vibrational characteristics in their electronic ground states. In all cases the complexes were predicted to be stable with respect to the constituent monomers. The interaction energy (Delta E) calculated using a super-molecular model is found to be in this order: PN...HF > PN...HCl > PN...HBr in the series examined. Analysis of various physically meaningful contributions arising from the Kitaura-Morokuma (KM) and reduced variational space self-consistent-field (RVS-SCF) energy decomposition procedures shows that the electrostatic energy has significant contribution to the over-all interaction energy. Dipole moment enhancement (Delta mu) was observed in these complexes expected of predominant dipole-dipole electrostatic interaction and was found to follow the trend PN...HF > PN...HCl > PN...HBr at the CCSD level. However, the DFT (X3LYP and B3LYP) and MP2 levels less accurately determined these values (in this order HF 0, nabla(2)rho(c) > 0 and H(c) > 0 at the BCP) whilst the bonds in PN (rho(c) > 0, nabla(2)rho(c) > 0 and H(c) 0, nabla(2)rho(c) BD*(HX) delocalization.

  11. Ab initio electronic band structure calculation of InP in the wurtzite phase

    Science.gov (United States)

    Dacal, Luis C. O.; Cantarero, Andrés

    2011-05-01

    We present ab initio calculations of the InP band structure in the wurtzite phase and compare it with that of the zincblende phase. In both calculations, we use the full potential linearized augmented plane wave method as implemented in the WIEN2k code and the modified Becke-Johnson exchange potential, which provides an improved value of the bandgap. The structural optimization of the wurtizte InP gives a=0.4150 nm, c=0.6912 nm, and an internal parameter u=0.371, showing the existence of a spontaneous polarization along the growth axis. As compared to the ideal wurtzite structure (that with the lattice parameter derived from the zincblende structure calculations), the actual wurtzite structure is compressed (-1.3%) in plane and expanded (0.7%) along the c-direction. The value of the calculated band gaps agrees well with recent optical experiments. The calculations are also consistent with the optical transitions found using polarized light.

  12. EM simulation assisted parameter extraction for the modeling of transferred-substrate InP HBTs

    DEFF Research Database (Denmark)

    Johansen, Tom Keinicke; Weimann, Nils; Doerner, Ralf

    2017-01-01

    In this paper an electromagnetic (EM) simulation assisted parameters extraction procedure is demonstrated for accurate modeling of down-scaled transferred-substrate InP HBTs. The external parasitic network associated with via transitions and device electrodes is carefully extracted from calibrate...

  13. Raman spectroscopy for characterization of annealing of ion-implanted InP

    International Nuclear Information System (INIS)

    Myers, D.R.; Gourley, P.L.; Vaidyanathan, K.V.; Dunlap, H.L.

    1983-01-01

    Raman spectroscopy has been used as a noncontacting, nondestructive tool to evaluate the properties of Si + - and Be + implanted InP samples annealed at temperatures ranging from 600 to 750C using phospho-silicate glass (PSG) as the encapsulant. Carrier activation, carrier mobility and recovery of damage as a function of anneal temperature obtained from analysis of Raman data agree very well with independent electrical measurements. (author)

  14. The empirical connection between (p,n) cross sections and beta decay transition strengths

    International Nuclear Information System (INIS)

    Taddeucci, T.N.

    1988-01-01

    A proportionality is assumed to exist between 0/degree/ (p,n) cross sections and the corresponding beta decay transition strengths. The validity of this assumption is tested by comparison of measured (p,n) cross sections and analogous beta decay strengths. Distorted waves impulse approximation calculations also provide useful estimates of the accuracy of the proportionality relationship. 14 refs., 10 figs

  15. Electronic band structure calculations for GaxIn1−xASyP1−y alloys lattice matched to InP

    International Nuclear Information System (INIS)

    Bechiri, A; Benmakhlouf, F; Allouache, H; Bacha, S; Bouarissa, N

    2012-01-01

    A pseudopotential formalism coupled with the virtual crystal approximation are applied to study the effect of compositional disorder upon electronic band structure of cubic Ga x In 1−x As y P 1−y quarternary alloys lattice matched to InP. The effects of compositional variations are properly included in the calculations. Very good agreement is obtained between the calculated values and the available experimental data for the lattice–matched alloy to InP. The absorption at the fundamental optical gaps is found to be direct within a whole range of the y composition whatever the lattice-matching to the substrate of interest. The alloy system Ga x In 1−x As y P 1−y lattice matched to InP is suggested to be suitable for an efficient light emitting device (ELED) material.

  16. Ink jet assisted metallization for low cost flat plate solar cells

    Science.gov (United States)

    Teng, K. F.; Vest, R. W.

    1987-01-01

    Computer-controlled ink-jet-assisted metallization of the front surface of solar cells with metalorganic silver inks offers a maskless alternative method to conventional photolithography and screen printing. This method can provide low cost, fine resolution, reduced process complexity, avoidance of degradation of the p-n junction by firing at lower temperature, and uniform line film on rough surface of solar cells. The metallization process involves belt furnace firing and thermal spiking. With multilayer ink jet printing and firing, solar cells of about 5-6 percent efficiency without antireflection (AR) coating can be produced. With a titanium thin-film underlayer as an adhesion promoter, solar cells of average efficiency 8.08 percent without AR coating can be obtained. This efficiency value is approximately equal to that of thin-film solar cells of the same lot. Problems with regard to lower inorganic content of the inks and contact resistance are noted.

  17. Role of electrode metallization in the performance of bulk semi-insulating InP radiation detectors

    International Nuclear Information System (INIS)

    Zatko, B.; Dubecky, F.; Prochazkova, O.; Necas, V.

    2007-01-01

    This work deals with the study of three different electrode metallizations with the aim to form a Schottky barrier contact. Electrode geometry corresponds to the requirements of digital radiography systems. As substrates bulk Liquid Encapsulated Czochralski (LEC) SI InP wafers doped with Fe and Fe+Zn are used. Results of this study show that no one of the used metallization performs as a blocking contact. However, detectors with Ti/Pt/Au metallization attained a relatively good energy resolution of 7.0 keV in full-width at half-maximum (FWHM) and the charge collection efficiency (CCE) higher than 83% for 122 keV γ-photons at 255 K. The development of SI InP radiation detectors and in particular their electrode technology is discussed in the light of observed results

  18. Manufacturing P-N junctions in germanium bodies

    International Nuclear Information System (INIS)

    Hall, R.N.

    1980-01-01

    A method of producing p-n junctions in Ge so as to facilitate their use as radiation detectors involves forming a body of high purity p-type germanium, diffusing lithium deep into the body, in the absence of electrolytic processes, to form a junction between n-type and p-type germanium greater than 1 mm depth. (UK)

  19. Sb2S3:C/CdS p-n junction by laser irradiation

    International Nuclear Information System (INIS)

    Arato, A.; Cardenas, E.; Shaji, S.; O'Brien, J.J.; Liu, J.; Castillo, G. Alan; Das Roy, T.K.; Krishnan, B.

    2009-01-01

    In this paper, we report laser irradiated carbon doping of Sb 2 S 3 thin films and formation of a p-n junction photovoltaic structure using these films. A very thin carbon layer was evaporated on to chemical bath deposited Sb 2 S 3 thin films of approximately 0.5 μm in thickness. Sb 2 S 3 thin films were prepared from a solution containing SbCl 3 and Na 2 S 2 O 3 at 27 deg. C for 5 h and the films obtained were highly resistive. These C/Sb 2 S 3 thin films were irradiated by an expanded laser beam of diameter approximately 0.5 cm (5 W power, 532 nm Verdi laser), for 2 min at ambient atmosphere. Morphology and composition of these films were analyzed. These films showed p-type conductivity due to carbon diffusion (Sb 2 S 3 :C) by the thermal energy generated by the absorption of laser radiation. In addition, these thin films were incorporated in a photovoltaic structure Ag/Sb 2 S 3 :C/CdS/ITO/Glass. For this, CdS thin film of 50 nm in thickness was deposited on a commercially available ITO coated glass substrate from a chemical bath containing CdCl 2 , sodium citrate, NH 4 OH and thiourea at 70 deg. C . On the CdS film, Sb 2 S 3 /C layers were deposited. This multilayer structure was subjected to the laser irradiation, C/Sb 2 S 3 side facing the beam. The p-n junction formed by p-Sb 2 S 3 :C and n-type CdS showed V oc = 500 mV and J sc = 0.5 mA/cm 2 under illumination by a tungsten halogen lamp. This work opens up a new method to produce solar cell structures by laser assisted material processing

  20. Hopping conductivity via deep impurity states in InP

    International Nuclear Information System (INIS)

    Kuznetsov, V.P.; Messerer, M.A.; Omel'yanovskij, Eh.M.

    1984-01-01

    Hopping (epsilon 3 ) and Mott conductivities via deep impurity compounds with localization radius below 10 A have been studied using as an example Mn in InP. It is shown, that the existing theory of hopping conductivity in low-alloyed semiconductors with Na 3 << 1 can be Used for the case of deep centres as successfully as for the case of insignificant hydrogen-like impurities. Fundamental parameters of the theory: localization radius of wave function of deep impurities, state density near the Fermi level, mean hop length, are determined

  1. The ZnO p-n homojunctions modulated by ZnMgO barriers

    International Nuclear Information System (INIS)

    Yang, Jing-Jing; Fang, Qing-Qing; Wang, Dan-Dan; Du, Wen-Han

    2015-01-01

    In this paper, we fabricated the ultrathin ZnO p-n homojunctions, which modulated by ZnMgO asymmetrical double barriers (ADB). The ADB p-n homojunctions displays step-like curve in the absorption spectrums, this is the first time that quantum confinement effect has been observed in the absorption spectrums at room temperature (RT). The Hall-effect data confirm there is 2-dimensional electron gas in the interface of the ZnMgO ADB p-n junctions. The quantum confinement effect enhances the hall-mobility μ to 10 3 cm 2 V −1 s −1 based on the polarity of the films. There was no rectification property in the ZnO homojunctions with thickness of 250nm, however, when the ADB was added in the n-type layer of the homojunctions, it displays a typical Zener diode rectification property in the I-V curve

  2. Optical properties of ion-implanted InP and GaAs: Selectivity-excited photoluminescence spectra

    International Nuclear Information System (INIS)

    Makita, Yunosuke; Yamada, Akimasa; Kimura, Shinji; Niki, Shigeru; Yoshinaga, Hiroshi; Matsumori, Tokue; Iida, Tsutomu; Uekusa, Ichiro

    1993-01-01

    Implantation of Mg+ ions was carried out into high purity InP grown by liquid encapsulated Czochralski method. Mg+ ion-implanted InP presented the formation of plural novel emissions with increasing Mg concentration, [Mg] in the low temperature photoluminescence spectra. Selectively-excited photoluminescence (SPL) measurements were made to examine the features of two-hole replicas pertinent to the emissions of excitons bound to neutral Mg and residual Zn acceptors. Systematic variation of the emission intensities from the two types of two-hole replicas was found to be utilized for the evaluation of ion-implanted materials. The significant discrepancy of emission spectra between PL and SPL was attributed to the difference of the depth examined by using the excitation light with high and low absorption coefficient. The results revealed that the diffusion of ion-implanted Mg is extremely enhanced when [Mg] exceeds 1x10 17 cm -3

  3. Imaging the p-n junction in a gallium nitride nanowire with a scanning microwave microscope

    Energy Technology Data Exchange (ETDEWEB)

    Imtiaz, Atif [Physical Measurement Laboratory, National Institute of Standards and Technology, Boulder, Colorado 80305 (United States); Department of Electrical, Computer, and Energy Engineering, University of Colorado, Boulder, Colorado 80309 (United States); Wallis, Thomas M.; Brubaker, Matt D.; Blanchard, Paul T.; Bertness, Kris A.; Sanford, Norman A.; Kabos, Pavel, E-mail: kabos@boulder.nist.gov [Physical Measurement Laboratory, National Institute of Standards and Technology, Boulder, Colorado 80305 (United States); Weber, Joel C. [Physical Measurement Laboratory, National Institute of Standards and Technology, Boulder, Colorado 80305 (United States); Department of Mechanical Engineering, University of Colorado, Boulder, Colorado 80309 (United States); Coakley, Kevin J. [Information Technology Laboratory, National Institute of Standards and Technology, Boulder, Colorado 80305 (United States)

    2014-06-30

    We used a broadband, atomic-force-microscope-based, scanning microwave microscope (SMM) to probe the axial dependence of the charge depletion in a p-n junction within a gallium nitride nanowire (NW). SMM enables the visualization of the p-n junction location without the need to make patterned electrical contacts to the NW. Spatially resolved measurements of S{sub 11}{sup ′}, which is the derivative of the RF reflection coefficient S{sub 11} with respect to voltage, varied strongly when probing axially along the NW and across the p-n junction. The axial variation in S{sub 11}{sup ′}  effectively mapped the asymmetric depletion arising from the doping concentrations on either side of the junction. Furthermore, variation of the probe tip voltage altered the apparent extent of features associated with the p-n junction in S{sub 11}{sup ′} images.

  4. Study on synthesis, kit formulation and chemical kinetics of dissociation of 99mTc labeled PnAO biotin complex

    International Nuclear Information System (INIS)

    Afshan, A.; Jafri, S.R.A.; Maecke, H.

    2004-01-01

    Full text: A bifunctional ligand of PnAO-biotin has recently been synthesized, with a better percentage yield of 63% in the presence of newly developed coupling agent 0-(7-azabenzotriazol-1-yl)-1,1,3,3-tetramethyluronium hexaflorophos phate (HATU). Then lyophilized kit with 150μg of PnAObiotin has been developed and labeled with high specific activity of technetium-99m (2500-3000MBq) to get maximum radiochemical purity of 99mTc-PnAO-biotin complex i.e. > 97%. The association of avidin and streptavidin is among the strongest known non-covalent protein ligand interaction Ka 1015 M-1 and 1013 M-1 respectively. We measured the dissociation rate constant of PnAO-biotin from avidin and streptavidin challenged with excess of cold biotin. For the separation of bound and free-labeled biotin we employed ultrafilteration technique. The results of these experiments demonstrated that the non-covalent binding between 99mTc-PnAO-biotin with avidin and 99mTc-PnAO-biotin with streptavidin is more than 99%. Both biotin-binding proteins exhibited a faster initial phase and the rate of dissociation of 99mTc-PnAO-biotin with avidin is found to be 8.2x10-8 at 250C and 2.6x10-7 at 370C while the rate of dissociation 99mTc-PnAO-biotin from streptavidin is found to be 6x10-7 at 250C and 1.06x10-6 at 370C. The in-vitro study of the kinetics of dissociation exhibits the strong interaction of 99mTc-PnAO-biotin complex with both proteins, which suggests that this bifunctional PnAO-biotin ligand can be used for tumor localization with monoclonal antibodies to achieve high tumor to non-tumor ratio. (author)

  5. Systematic optimization of quantum junction colloidal quantum dot solar cells

    KAUST Repository

    Liu, Huan

    2012-01-01

    The recently reported quantum junction architecture represents a promising approach to building a rectifying photovoltaic device that employs colloidal quantum dot layers on each side of the p-n junction. Here, we report an optimized quantum junction solar cell that leverages an improved aluminum zinc oxide electrode for a stable contact to the n-side of the quantum junction and silver doping of the p-layer that greatly enhances the photocurrent by expanding the depletion region in the n-side of the device. These improvements result in greater stability and a power conversion efficiency of 6.1 under AM1.5 simulated solar illumination. © 2012 American Institute of Physics.

  6. InP monolithically integrated label swapper device for spectral amplitude coded optical packet networks

    NARCIS (Netherlands)

    Muñoz, P.; García-Olcina, R.; Doménech, J.D.; Rius, M.; Sancho, J.C.; Capmany, J.; Chen, L.R.; Habib, C.; Leijtens, X.J.M.; Vries, de T.; Heck, M.J.R.; Augustin, L.M.; Nötzel, R.; Robbins, D.J.

    2010-01-01

    In this paper a label swapping device, for spectral amplitude coded optical packet networks, fully integrated using InP technology is presented. Compared to previous demonstrations using discrete component assembly, the device footprint is reduced by a factor of 105 and the operation speed is

  7. Southern hemisphere solar radio heliograph

    Science.gov (United States)

    Sawant, H. S.; Fernandes, F. C. R.; Neri, J. A. C. F.; Cecatto, J. R.; Faria, C.; Stephany, S.; Rosa, R. R.; Andrade, M. C.; Ludke, E.; Subramanian, K. R.; Ramesh, R.; Sundrarajan, M. S.; Sankararaman, M. R.; Ananthakrishnan, S.; Swarup, G.; Boas, J. W. V.; Botti, L. C. L.; Moron, C. E.; Saito, J. H.; Karlický, M.

    2002-12-01

    The Brazilian Decimetric Array (BDA) is being developed at National Institute for Space Research (INPE) as an international collaborative program. Initially, the BDA will operate in the tuneable frequency range of 1.2-1.7 GHz. The initial planned baseline for BDA 'T' array is 256×144 m and will be extended to 2.2×1.1 km. In this paper, we present the results of developments concerning the prototype of BDA (PBDA). The PBDA will initially operate in the frequency range of 1.2-1.7 GHz, with a five-antenna array, using 4-meter parabolic dishes with altitude and azimuth mountings and complete tracking capability. The spatial resolution for solar images with the PBDA will be about 3.5 arc-minutes leading to a sensitivity of ≍2×104 mJy/beam for an integration time of 1 sec. The array will be installed at -22°41'19" latitude and 45°0'22" W longitude and it is under operation between 9 and 21 UT for continuous solar flux monitoring. Details of the PBDA system are presented.

  8. Fokker-Planck-Rosenbluth-type equations for self-gravitating systems in the 1PN approximation

    International Nuclear Information System (INIS)

    Ramos-Caro, Javier; Gonzalez, Guillermo A

    2008-01-01

    We present two formulations of Fokker-Planck-Rosenbluth-type (FPR) equations for many-particle self-gravitating systems, with first-order relativistic corrections in the post-Newtonian approach (1PN). The first starts from a covariant Fokker-Planck equation for a simple gas, introduced recently by Chacon-Acosta and Kremer (2007 Phys. Rev. E 76 021201). The second derivation is based on the establishment of an 1PN-BBGKY hierarchy, developed systematically from the 1PN microscopic law of force and using the Klimontovich-Dupree (KD) method. We close the hierarchy by the introduction of a two-point correlation function that describes adequately the relaxation process. This picture reveals an aspect that is not considered in the first formulation: the contribution of ternary correlation patterns to the diffusion coefficients, as a consequence of the nature of 1PN interaction. Both formulations can be considered as a generalization of the equation derived by Rezania and Sobouti (2000 Astron. Astrophys. 354 1110), to stellar systems where the relativistic effects of gravitation play a significant role

  9. Charge exchange reactions and solar neutrino detection in 81Br

    International Nuclear Information System (INIS)

    Liu, K.F.; Gabbard, F.

    1983-01-01

    The feasibility of 81 Br as the detector of the solar neutrino flux hinges upon the knowledge of the Gamow-Teller matrix element from the ground state of 81 Br to the (5/2) - state at 0.457 MeV in 81 Kr. The possibility of obtaining this matrix element is discussed in terms of the (p,n) and ( 3 He, t) charge exchange reactions. .ID CR2009 .PG 98 112

  10. Regrowth of InP by MOVPE on dry-etched heterostructures of InP-GaInAsP

    Energy Technology Data Exchange (ETDEWEB)

    Catana, A. (IBM Research Div., Zurich Research Lab., Rueschlikon (Switzerland)); Broom, R.F. (IBM Research Div., Zurich Research Lab., Rueschlikon (Switzerland)); Germann, R. (IBM Research Div., Zurich Research Lab., Rueschlikon (Switzerland)); Roentgen, P. (IBM Research Div., Zurich Research Lab., Rueschlikon (Switzerland))

    1993-04-01

    The MOVPE growth behavior of InP on masked and dry-etched ridges in InP/InGaAsP heterostructures grown on (001)-oriented InP substrates has been studied by scanning electron and transmission electron microscopy. It is found that the orientation of the ridges is critical for obtaining good planarization. For ridges oriented along the 100 direction, the growth is uniform and defect-free, leasing to a plane surface. In the orthogonal 110 direction 60 twins are nucleated adjacent to the walls of the ridge. The resultant high density of (111)/(001) facets enhances the growth rate in these regions, leading to projecting walls at the sides of the ridge. (orig.)

  11. Epitaxial Growth of an Organic p-n Heterojunction: C60 on Single-Crystal Pentacene.

    Science.gov (United States)

    Nakayama, Yasuo; Mizuno, Yuta; Hosokai, Takuya; Koganezawa, Tomoyuki; Tsuruta, Ryohei; Hinderhofer, Alexander; Gerlach, Alexander; Broch, Katharina; Belova, Valentina; Frank, Heiko; Yamamoto, Masayuki; Niederhausen, Jens; Glowatzki, Hendrik; Rabe, Jürgen P; Koch, Norbert; Ishii, Hisao; Schreiber, Frank; Ueno, Nobuo

    2016-06-01

    Designing molecular p-n heterojunction structures, i.e., electron donor-acceptor contacts, is one of the central challenges for further development of organic electronic devices. In the present study, a well-defined p-n heterojunction of two representative molecular semiconductors, pentacene and C60, formed on the single-crystal surface of pentacene is precisely investigated in terms of its growth behavior and crystallographic structure. C60 assembles into a (111)-oriented face-centered-cubic crystal structure with a specific epitaxial orientation on the (001) surface of the pentacene single crystal. The present experimental findings provide molecular scale insights into the formation mechanisms of the organic p-n heterojunction through an accurate structural analysis of the single-crystalline molecular contact.

  12. Submicron InP DHBT technology for high-speed high-swing mixed-signal ICs

    DEFF Research Database (Denmark)

    Godin, Jean; Nodjiadjim, V.; Riet, Muriel

    2008-01-01

    We report on the development of a submicron InP DHBT technology, optimized for the fabrication of 50-GHz-clock mixed signal ICs. In-depth study of device geometry and structure has allowed to get the needed performances and yield. Special attention has been paid to critical thermal behavior. Vari...... applications of interest....

  13. Diffusion length measurements in bulk and epitaxially grown 3-5 semiconductors using charge collection microscopy

    Science.gov (United States)

    Leon, R. P.

    1987-01-01

    Diffusion lengths and surface recombination velocities were measured in GaAs diodes and InP finished solar cells. The basic techniques used was charge collection microscopy also known as electron beam induced current (EBIC). The normalized currents and distances from the pn junction were read directly from the calibrated curves obtained while using the line scan mode in an SEM. These values were then equated to integral and infinite series expressions resulting from the solution of the diffusion equation with both extended generation and point generation functions. This expands previous work by examining both thin and thick samples. The surface recombination velocity was either treated as an unknown in a system of two equations, or measured directly using low e(-) beam accelerating voltages. These techniques give accurate results by accounting for the effects of surface recombination and the finite size of the generation volume.

  14. Experimental studies of thin films deposition by magnetron sputtering method for CIGS solar cell fabrication

    Directory of Open Access Journals (Sweden)

    Gułkowski Sławomir

    2017-01-01

    Full Text Available Among a variety of the thin film solar cell technologies of second generation, copper-indium-gallium-diselenide device (CIGS with the latest highest lab cell efficiency record of 22.4 % seems to be the most promising for the power generation. This is partly due to the advantages of using low cost films of few microns thick not only as a metallic contacts but also as a main structure of the solar cell consisted of high quality semiconductor layers. This paper reports the experimental studies of the CIGS absorber formation on Soda Lime Glass substrate covered by thin molybdenum film as a back contact layer. All structures were deposited with the use of magnetron sputtering method only. Technological parameters of the deposition process such as deposition power, pressure and deposition time were optimized for each layer of the structure. Mo back contact was examined in terms of resistivity. EDS measurements were carried out to verify stoichiometric composition of CIGS absorber. Thin film of Al was used as a top contact in order to examine the quality of p-n junction. The I-V electrical characteristic of the p-n junction was analysed in terms of solar cell application.

  15. A miniature solar device for overall water splitting consisting of series-connected spherical silicon solar cells

    KAUST Repository

    Kageshima, Yosuke

    2016-04-18

    A novel “photovoltaics (PV) + electrolyzer” concept is presented using a simple, small, and completely stand-alone non-biased device for solar-driven overall water splitting. Three or four spherical-shaped p-n junction silicon balls were successfully connected in series, named “SPHELAR.” SPHELAR possessed small projected areas of 0.20 (3PVs) and 0.26 cm2 (4PVs) and exhibited working voltages sufficient for water electrolysis. Impacts of the configuration on the PV module performance were carefully analyzed, revealing that a drastic increase in the photocurrent (≈20%) was attained by the effective utilization of a reflective sheet. Separate investigations on the electrocatalyst performance showed that non-noble metal based materials with reasonably small sizes (<0.80 cm2) exhibited substantial currents at the PV working voltage. By combining the observations of the PV characteristics, light management and electrocatalyst performance, solar-driven overall water splitting was readily achieved, reaching solar-to-hydrogen efficiencies of 7.4% (3PVs) and 6.4% (4PVs).

  16. A miniature solar device for overall water splitting consisting of series-connected spherical silicon solar cells

    KAUST Repository

    Kageshima, Yosuke; Shinagawa, Tatsuya; Kuwata, Takaaki; Nakata, Josuke; Minegishi, Tsutomu; Takanabe, Kazuhiro; Domen, Kazunari

    2016-01-01

    A novel “photovoltaics (PV) + electrolyzer” concept is presented using a simple, small, and completely stand-alone non-biased device for solar-driven overall water splitting. Three or four spherical-shaped p-n junction silicon balls were successfully connected in series, named “SPHELAR.” SPHELAR possessed small projected areas of 0.20 (3PVs) and 0.26 cm2 (4PVs) and exhibited working voltages sufficient for water electrolysis. Impacts of the configuration on the PV module performance were carefully analyzed, revealing that a drastic increase in the photocurrent (≈20%) was attained by the effective utilization of a reflective sheet. Separate investigations on the electrocatalyst performance showed that non-noble metal based materials with reasonably small sizes (<0.80 cm2) exhibited substantial currents at the PV working voltage. By combining the observations of the PV characteristics, light management and electrocatalyst performance, solar-driven overall water splitting was readily achieved, reaching solar-to-hydrogen efficiencies of 7.4% (3PVs) and 6.4% (4PVs).

  17. Dopant-free twinning superlattice formation in InSb and InP nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Yuan, Xiaoming [School of Physics and Electronics, Hunan Key Laboratory for Supermicrostructure and Ultrafast Process, Central South University, Changsha, Hunan (China); Department of Electronic Materials Engineering, Research School of Physics and Engineering, The Australian National University, Canberra, ACT (Australia); Guo, Yanan; Caroff, Philippe; Tan, Hark Hoe; Jagadish, Chennupati [Department of Electronic Materials Engineering, Research School of Physics and Engineering, The Australian National University, Canberra, ACT (Australia); He, Jun [School of Physics and Electronics, Hunan Key Laboratory for Supermicrostructure and Ultrafast Process, Central South University, Changsha, Hunan (China)

    2017-11-15

    Periodic arrangement of twin planes creates a controllable polytype that can affect both the electronic and optical properties of nanowires. The approach that is most used for inducing twinning superlattice (TSL) formation in III-V nanowires is introducing impurity dopants during growth. Here, we demonstrate that controlling the growth parameters is sufficient to produce regular twinning planes in Au-catalysed InSb and InP nanowires. Our results show that TSL formation in InSb nanowires only exists in a very narrow growth window. We suggest that growth conditions induce a high concentration of In (or Sb) in the Au droplet, which plays a similar role to that of surfactant impurities such as Zn, and increases the droplet wetting angle to yield a geometry that is favorable for TSL formation. The demonstration of TSL structure in InSb and InP nanowires by controlling the input of In (or Sb) further enhances fundamental understanding of TSL formation in III-V nanowires and allows us to tune the properties of these nanowires by crystal phase engineering. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  18. High-efficiency red electroluminescent device based on multishelled InP quantum dots.

    Science.gov (United States)

    Jo, Jung-Ho; Kim, Jong-Hoon; Lee, Ki-Heon; Han, Chang-Yeol; Jang, Eun-Pyo; Do, Young Rag; Yang, Heesun

    2016-09-01

    We report on the synthesis of highly fluorescent red-emitting InP quantum dots (QDs) and their application to the fabrication of a high-efficiency QD-light-emitting diode (QLED). The core/shell heterostructure of the QDs is elaborately tailored toward a multishelled structure with a composition-gradient ZnSeS intermediate shell and an outer ZnS shell. Using the resulting InP/ZnSeS/ZnS QDs as an emitting layer, all-solution-processible red InP QLEDs are fabricated with a hybrid multilayered device structure having an organic hole transport layer (HTL) and an inorganic ZnO nanoparticle electron transport layer. Two HTLs of poly(9-vinlycarbazole) or poly[(9,9-dioctylfluorenyl-2,7-diyl)-co-(4,4'-(N-(4-sec-butylphenyl))diphenyl-amine), whose hole mobilities are different by at least three orders of magnitude, are individually applied for QLED fabrication and such HTL-dependent device performances are compared. Our best red device displays exceptional figures of merit such as a maximum luminance of 2849  cd/m2, a current efficiency of 4.2  cd/A, and an external quantum efficiency of 2.5%.

  19. Dopant-free twinning superlattice formation in InSb and InP nanowires

    International Nuclear Information System (INIS)

    Yuan, Xiaoming; Guo, Yanan; Caroff, Philippe; Tan, Hark Hoe; Jagadish, Chennupati; He, Jun

    2017-01-01

    Periodic arrangement of twin planes creates a controllable polytype that can affect both the electronic and optical properties of nanowires. The approach that is most used for inducing twinning superlattice (TSL) formation in III-V nanowires is introducing impurity dopants during growth. Here, we demonstrate that controlling the growth parameters is sufficient to produce regular twinning planes in Au-catalysed InSb and InP nanowires. Our results show that TSL formation in InSb nanowires only exists in a very narrow growth window. We suggest that growth conditions induce a high concentration of In (or Sb) in the Au droplet, which plays a similar role to that of surfactant impurities such as Zn, and increases the droplet wetting angle to yield a geometry that is favorable for TSL formation. The demonstration of TSL structure in InSb and InP nanowires by controlling the input of In (or Sb) further enhances fundamental understanding of TSL formation in III-V nanowires and allows us to tune the properties of these nanowires by crystal phase engineering. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  20. Trap-mediated electronic transport properties of gate-tunable pentacene/MoS2 p-n heterojunction diodes.

    Science.gov (United States)

    Kim, Jae-Keun; Cho, Kyungjune; Kim, Tae-Young; Pak, Jinsu; Jang, Jingon; Song, Younggul; Kim, Youngrok; Choi, Barbara Yuri; Chung, Seungjun; Hong, Woong-Ki; Lee, Takhee

    2016-11-10

    We investigated the trap-mediated electronic transport properties of pentacene/molybdenum disulphide (MoS 2 ) p-n heterojunction devices. We observed that the hybrid p-n heterojunctions were gate-tunable and were strongly affected by trap-assisted tunnelling through the van der Waals gap at the heterojunction interfaces between MoS 2 and pentacene. The pentacene/MoS 2 p-n heterojunction diodes had gate-tunable high ideality factor, which resulted from trap-mediated conduction nature of devices. From the temperature-variable current-voltage measurement, a space-charge-limited conduction and a variable range hopping conduction at a low temperature were suggested as the gate-tunable charge transport characteristics of these hybrid p-n heterojunctions. Our study provides a better understanding of the trap-mediated electronic transport properties in organic/2-dimensional material hybrid heterojunction devices.

  1. Pn seismic wave travel time at the Semipalatinsk Test Site - Borovoe seismic station trace

    International Nuclear Information System (INIS)

    An, V.A.; Kaazik, P.B.; Ovchinnikov, V.M.

    2001-01-01

    This paper preparation involved 160 explosions at the Degelen Site conducted in 1961-1989 and 89 explosions at the Balapan Site conducted in 1968-1989. Pn wave travel time was tied to the sea level in accordance with velocity characteristics of the explosion hypocenter medium; and to average epicentral distance for every site basing on their local travel time curves of Pn wave relative to Borovoe station. Maximum amplitude of mean-year travel times variations is 0.3-0.5 s as at the Nevada Test Site - Borovoe trace and Mirniy (Antarctica). However, the linear trend in contrast to previous traces has negative sign (0.08 s for Degelen and 0.1 s for Balapan). Thus, Pn wave velocity increases with calendar time. (author)

  2. Balanced G-band Gm-boosted frequency doublers in transferred substrate InP HBT technology

    DEFF Research Database (Denmark)

    Johansen, Tom Keinicke; Thualfiqar, Al-Sawaf; Weimann, Nils

    2016-01-01

    In this paper, balanced G-band Gm-boosted frequency doublers in transferred substrate (TS) InP HBT technology are reported for the first time. The Gm-boosted frequency doublers consist of a phase compensated Marchand balun, Gm-boosted doubler stage, and an optional cascode gain stage at the outpu...

  3. W-Band InP Wideband MMIC LNA with 30K Noise Temperature

    Science.gov (United States)

    Weinreb, S.; Lai, R.; Erickson, N.; Gaier, T.; Wielgus, J.

    2000-01-01

    This paper describe a millimeter wave low noise amplifier with extraordinary low noise, low consumption, and wide frequency range. These results are achieved utilizing state-of-the-art InP HEMT transistors coupled with CPW circuit design. The paper describes the transistor models, modeled and measured on-wafer and in-module results at both 300K am 24K operating temperatures for many samples of the device.

  4. Temperature-Dependent Asymmetry of Anisotropic Magnetoresistance in Silicon p-n Junctions.

    Science.gov (United States)

    Yang, D Z; Wang, T; Sui, W B; Si, M S; Guo, D W; Shi, Z; Wang, F C; Xue, D S

    2015-09-01

    We report a large but asymmetric magnetoresistance in silicon p-n junctions, which contrasts with the fact of magnetoresistance being symmetric in magnetic metals and semiconductors. With temperature decreasing from 293 K to 100 K, the magnetoresistance sharply increases from 50% to 150% under a magnetic field of 2 T. At the same time, an asymmetric magnetoresistance, which manifests itself as a magnetoresistance voltage offset with respect to the sign of magnetic field, occurs and linearly increases with magnetoresistance. More interestingly, in contrast with other materials, the lineshape of anisotropic magnetoresistance in silicon p-n junctions significantly depends on temperature. As temperature decreases from 293 K to 100 K, the width of peak shrinks from 90° to 70°. We ascribe these novel magnetoresistance to the asymmetric geometry of the space charge region in p-n junction induced by the magnetic field. In the vicinity of the space charge region the current paths are deflected, contributing the Hall field to the asymmetric magnetoresistance. Therefore, the observed temperature-dependent asymmetry of magnetoresistance is proved to be a direct consequence of the spatial configuration evolution of space charge region with temperature.

  5. Three-Stage InP Submillimeter-Wave MMIC Amplifier

    Science.gov (United States)

    Pukala, David; Samoska, Lorene; Man, King; Gaier, Todd; Deal, William; Lai, Richard; Mei, Gerry; Makishi, Stella

    2008-01-01

    A submillimeter-wave monolithic integrated- circuit (S-MMIC) amplifier has been designed and fabricated using an indium phosphide (InP) 35-nm gate-length high electron mobility transistor (HEMT) device, developed at Northrop Grumman Corporation. The HEMT device employs two fingers each 15 micrometers wide. The HEMT wafers are grown by molecular beam epitaxy (MBE) and make use of a pseudomorphic In0.75Ga0.25As channel, a silicon delta-doping layer as the electron supply, an In0.52Al0.48As buffer layer, and an InP substrate. The three-stage design uses coplanar waveguide topology with a very narrow ground-to-ground spacing of 14 micrometers. Quarter-wave matching transmission lines, on-chip metal-insulator-metal shunt capacitors, series thin-film resistors, and matching stubs were used in the design. Series resistors in the shunt branch arm provide the basic circuit stabilization. The S-MMIC amplifier was measured for S-parameters and found to be centered at 320 GHz with 13-15-dB gain from 300-345 GHz. This chip was developed as part of the DARPA Submillimeter Wave Imaging Focal Plane Technology (SWIFT) program (see figure). Submillimeter-wave amplifiers could enable more sensitive receivers for earth science, planetary remote sensing, and astrophysics telescopes, particularly in radio astronomy, both from the ground and in space. A small atmospheric window at 340 GHz exists and could enable ground-based observations. However, the submillimeter-wave regime (above 300 GHz) is best used for space telescopes as Earth s atmosphere attenuates most of the signal through water and oxygen absorption. Future radio telescopes could make use of S-MMIC amplifiers for wideband, low noise, instantaneous frequency coverage, particularly in the case of heterodyne array receivers.

  6. Growth and anisotropic transport properties of self-assembled InAs nanostructures in InP

    International Nuclear Information System (INIS)

    Bierwagen, O.

    2007-01-01

    Self-assembled InAs nanostructures in InP, comprising quantum wells, quantum wires, and quantum dots, are studied in terms of their formation and properties. In particular, the structural, optical, and anisotropic transport properties of the nanostructures are investigated. The focus is a comprehending exploration of the anisotropic in-plane transport in large ensembles of laterally coupled InAs nanostructures. The self-assembled Stranski-Krastanov growth of InAs nanostructures is studied by gas-source molecular beam epitaxy on both nominally oriented and vicinal InP(001). Optical polarization of the interband transitions arising from the nanostructure type is demonstrated by photoluminescence and transmission spectroscopy. The experimentally convenient four-contact van der Pauw Hall measurement of rectangularly shaped semiconductors, usually applied to isotropic systems, is extended to yield the anisotropic transport properties. Temperature dependent transport measurements are performed in large ensembles of laterally closely spaced nanostructures. The transport of quantum wire-, quantum dash- and quantum dot containing samples is highly anisotropic with the principal axes of conductivity aligned to the directions. The direction of higher mobility is [ anti 110], which is parallel to the direction of the quantum wires. In extreme cases, the anisotropies exceed 30 for electrons, and 100 for holes. The extreme anisotropy for holes is due to diffusive transport through extended states in the [ anti 110], and hopping transport through laterally localized states in the [110] direction, within the same sample. A novel 5-terminal electronic switching device based on gate-controlled transport anisotropy is proposed. The gate-control of the transport anisotropy in modulation-doped, self-organized InAs quantum wires embedded in InP is demonstrated. (orig.)

  7. Growth and anisotropic transport properties of self-assembled InAs nanostructures in InP

    Energy Technology Data Exchange (ETDEWEB)

    Bierwagen, O.

    2007-12-20

    Self-assembled InAs nanostructures in InP, comprising quantum wells, quantum wires, and quantum dots, are studied in terms of their formation and properties. In particular, the structural, optical, and anisotropic transport properties of the nanostructures are investigated. The focus is a comprehending exploration of the anisotropic in-plane transport in large ensembles of laterally coupled InAs nanostructures. The self-assembled Stranski-Krastanov growth of InAs nanostructures is studied by gas-source molecular beam epitaxy on both nominally oriented and vicinal InP(001). Optical polarization of the interband transitions arising from the nanostructure type is demonstrated by photoluminescence and transmission spectroscopy. The experimentally convenient four-contact van der Pauw Hall measurement of rectangularly shaped semiconductors, usually applied to isotropic systems, is extended to yield the anisotropic transport properties. Temperature dependent transport measurements are performed in large ensembles of laterally closely spaced nanostructures. The transport of quantum wire-, quantum dash- and quantum dot containing samples is highly anisotropic with the principal axes of conductivity aligned to the <110> directions. The direction of higher mobility is [ anti 110], which is parallel to the direction of the quantum wires. In extreme cases, the anisotropies exceed 30 for electrons, and 100 for holes. The extreme anisotropy for holes is due to diffusive transport through extended states in the [ anti 110], and hopping transport through laterally localized states in the [110] direction, within the same sample. A novel 5-terminal electronic switching device based on gate-controlled transport anisotropy is proposed. The gate-control of the transport anisotropy in modulation-doped, self-organized InAs quantum wires embedded in InP is demonstrated. (orig.)

  8. Theoretical study on pp → pnπ+ reaction at medium energies

    International Nuclear Information System (INIS)

    Ouyang, Zhen; Xie, Jujun; Zou, Bingsong; Xu, Hushan

    2009-01-01

    The pp → pnπ + reaction is a channel with the largest total cross section for pp collision in COSY/CSR energy region. In this work, we investigate individual contributions from various N* and Δ* resonances with mass up to about 2 GeV for the pp → pnπ + reaction. We extend a resonance model, which can reproduce the observed total cross section quite well, to give theoretical predictions of various differential cross sections for the present reaction at T p = 2.88 GeV. It could serve as a reference for identifying new physics in the future experiments at HIRFL-CSR. (author)

  9. Biological constraints limit the use of rapamycin-inducible FKBP12-Inp54p for depleting PIP2 in dorsal root ganglia neurons.

    Science.gov (United States)

    Coutinho-Budd, Jaeda C; Snider, Samuel B; Fitzpatrick, Brendan J; Rittiner, Joseph E; Zylka, Mark J

    2013-09-08

    Rapamycin-induced translocation systems can be used to manipulate biological processes with precise temporal control. These systems are based on rapamycin-induced dimerization of FK506 Binding Protein 12 (FKBP12) with the FKBP Rapamycin Binding (FRB) domain of mammalian target of rapamycin (mTOR). Here, we sought to adapt a rapamycin-inducible phosphatidylinositol 4,5-bisphosphate (PIP2)-specific phosphatase (Inp54p) system to deplete PIP2 in nociceptive dorsal root ganglia (DRG) neurons. We genetically targeted membrane-tethered CFP-FRBPLF (a destabilized FRB mutant) to the ubiquitously expressed Rosa26 locus, generating a Rosa26-FRBPLF knockin mouse. In a second knockin mouse line, we targeted Venus-FKBP12-Inp54p to the Calcitonin gene-related peptide-alpha (CGRPα) locus. We hypothesized that after intercrossing these mice, rapamycin treatment would induce translocation of Venus-FKBP12-Inp54p to the plasma membrane in CGRP+ DRG neurons. In control experiments with cell lines, rapamycin induced translocation of Venus-FKBP12-Inp54p to the plasma membrane, and subsequent depletion of PIP2, as measured with a PIP2 biosensor. However, rapamycin did not induce translocation of Venus-FKBP12-Inp54p to the plasma membrane in FRBPLF-expressing DRG neurons (in vitro or in vivo). Moreover, rapamycin treatment did not alter PIP2-dependent thermosensation in vivo. Instead, rapamycin treatment stabilized FRBPLF in cultured DRG neurons, suggesting that rapamycin promoted dimerization of FRBPLF with endogenous FKBP12. Taken together, our data indicate that these knockin mice cannot be used to inducibly deplete PIP2 in DRG neurons. Moreover, our data suggest that high levels of endogenous FKBP12 could compete for binding to FRBPLF, hence limiting the use of rapamycin-inducible systems to cells with low levels of endogenous FKBP12.

  10. Fabrication and characterization of InP fresnel microlenses

    International Nuclear Information System (INIS)

    Diadiuk, V.; Walpole, J.N.; Liau, Z.L.

    1987-01-01

    Since diode lasers typically have a beam divergence of a few tens of degrees, collimating the laser outputs leads to greatly far-field patterns, which, in turn translates into more power in the main lobe of the combined output. Achieving this collimation in the case of a diode laser array, with its small device-to-device distance, requires an array of similarly spaced microlenses with very short focal length, small diameter and small F number. In this paper, the authors describe the fabrication and performance of a Fresnel microlens array etched directly in InP wafers; these microlenses have been used successfully to collimate the output of GainAsP/InP buried-heterostructure (BH) diode lasers

  11. Axial p-n junction and space charge limited current in single GaN nanowire

    Science.gov (United States)

    Fang, Zhihua; Donatini, Fabrice; Daudin, Bruno; Pernot, Julien

    2018-01-01

    The electrical characterizations of individual basic GaN nanostructures, such as axial nanowire (NW) p-n junctions, are becoming indispensable and crucial for the fully controlled realization of GaN NW based devices. In this study, electron beam induced current (EBIC) measurements were performed on two single axial GaN p-n junction NWs grown by plasma-assisted molecular beam epitaxy. I-V characteristics revealed that both ohmic and space charge limited current (SCLC) regimes occur in GaN p-n junction NW. Thanks to an improved contact process, both the electric field induced by the p-n junction and the SCLC in the p-part of GaN NW were disclosed and delineated by EBIC signals under different biases. Analyzing the EBIC profiles in the vicinity of the p-n junction under 0 V and reverse bias, we deduced a depletion width in the range of 116-125 nm. Following our previous work, the acceptor N a doping level was estimated to be 2-3 × 1017 at cm-3 assuming a donor level N d of 2-3 × 1018 at cm-3. The hole diffusion length in n-GaN was determined to be 75 nm for NW #1 and 43 nm for NW #2, demonstrating a low surface recombination velocity at the m-plane facet of n-GaN NW. Under forward bias, EBIC imaging visualized the electric field induced by the SCLC close to p-side contact, in agreement with unusual SCLC previously reported in GaN NWs.

  12. Axial p-n junction and space charge limited current in single GaN nanowire.

    Science.gov (United States)

    Fang, Zhihua; Donatini, Fabrice; Daudin, Bruno; Pernot, Julien

    2018-01-05

    The electrical characterizations of individual basic GaN nanostructures, such as axial nanowire (NW) p-n junctions, are becoming indispensable and crucial for the fully controlled realization of GaN NW based devices. In this study, electron beam induced current (EBIC) measurements were performed on two single axial GaN p-n junction NWs grown by plasma-assisted molecular beam epitaxy. I-V characteristics revealed that both ohmic and space charge limited current (SCLC) regimes occur in GaN p-n junction NW. Thanks to an improved contact process, both the electric field induced by the p-n junction and the SCLC in the p-part of GaN NW were disclosed and delineated by EBIC signals under different biases. Analyzing the EBIC profiles in the vicinity of the p-n junction under 0 V and reverse bias, we deduced a depletion width in the range of 116-125 nm. Following our previous work, the acceptor N a doping level was estimated to be 2-3 × 10 17 at cm -3 assuming a donor level N d of 2-3 × 10 18 at cm -3 . The hole diffusion length in n-GaN was determined to be 75 nm for NW #1 and 43 nm for NW #2, demonstrating a low surface recombination velocity at the m-plane facet of n-GaN NW. Under forward bias, EBIC imaging visualized the electric field induced by the SCLC close to p-side contact, in agreement with unusual SCLC previously reported in GaN NWs.

  13. Optical properties of InxGa1-xP/InP grown at high fluence Ga+ implantation on InP using focused ion beam

    International Nuclear Information System (INIS)

    Fang, Hsin-Chiao; Liu, Chuan-Pu; Dhara, Sandip

    2011-01-01

    Single-crystalline InP(1 0 0) substrate was implanted by 30 keV Ga + ions with fluences of 1 x 10 16 -1.5 x 10 17 cm -2 followed by post-annealing treatment at 750 o C to recover implantation-induced structural defects and activate dopants into the lattices. The optical property, composition, and microstructure of the Ga + -implanted InP were studied by Raman spectroscopy and transmission electron microscopy (TEM). Raman spectra show that the In x Ga 1-x P phase is formed at a critical fluence of 7 x 10 16 cm -2 . The newly grown phase was identified with the appearance of Ga rich TO InP and In rich TO GaP modes of a random alloy in the 1 bond-2 phonon mode configuration along with TEM structural identification.

  14. Photoeffect on the p-n silicon junction under conditions of interband heating of carriers by light

    Energy Technology Data Exchange (ETDEWEB)

    Andrianov, A V; Valov, P M; Sukhanov, V L; Tuchkevich, V V; Shmidt, N M [AN SSSR, Leningrad. Fiziko-Tekhnicheskij Inst.

    1980-05-01

    Photoeffect on the p-n silicon junction conditioned by interband heating of carriers by the CO/sub 2/-laser light has been studied experimentally at room temperature and under nonstationary conditions. Photoelectromotive force (p.e.m.f.) with the sign opposite to the value p.e.m.f. appears in the case of direct displacement of p-n structures. The p.e.m.f. value increases with the increase of direct desplacement. Photoelectrons are shown to make the main contribution into the mechanism of p.e.m.f. formation. Lateral p.e.m.f. connected with spreading currents in the direction parallel to the surface of the p-n junction appears in the p-n structure base. It has been found out that structures with highly alloyed emitter at reverse displacement operates under standard photodiod conditions, that is due to the semiconductor lattice heating by CO/sub 2/-laser irradiation.

  15. Photoeffect on the p-n silicon junction under conditions of interband heating of carriers by light

    International Nuclear Information System (INIS)

    Andrianov, A.V.; Valov, P.M.; Sukhanov, V.L.; Tuchkevich, V.V.; Shmidt, N.M.

    1980-01-01

    Photoeffect on the p-n silicon junction conditioned by interband heating of carriers by the CO 2 -laser light has been studied experimentally at room temperature and under nonstationary conditions. Photoelectromotive force (p.e.m.f.) with the sign opposite to the value p.e.m.f. appears in the case of direct displacement of p-n structures. The p.e.m.f. value increases with the increase of direct desplacement. Photoelectrons are shown to make the main contribution into the mechanism of p.e.m.f. formation. Lateral p.e.m.f. connected with spreading currents in the direction parallel to the surface of the p-n junction appears in the p-n structure base. It has been found out that structures with highly alloyed emitter at reverse displacement operates under standard photodiod conditions, that is due to the semiconductor lattice heating by CO 2 -laser irradiation

  16. Passive InP regenerator integrated on SOI for the support of broadband silicon modulators

    NARCIS (Netherlands)

    Tassaert, M.; Dorren, H.J.S.; Roelkens, G.; Raz, O.

    2012-01-01

    Passive signal regeneration based on the Membrane InP Switch (MIPS) is demonstrated. Because of the high confinement of light in the active region of the MIPS, the device acts as a saturable absorber with a highly non-linear response. Using this effect, the extinction ratio (ER) of low-ER signals

  17. Application of MSM InP detectors to the measurement of pulsed X-ray radiation

    Czech Academy of Sciences Publication Activity Database

    Ryc, L.; Dobrzanski, L.; Dubecký, L.; Kaczmarczyk, J.; Pfeifer, Miroslav; Riesz, F.; Slysz, W.; Surma, B.

    2008-01-01

    Roč. 163, 4-6 (2008), 559-567 ISSN 1042-0150 R&D Projects: GA MŠk(CZ) LC528 Institutional research plan: CEZ:AV0Z10100523 Keywords : InP detector * X-ray detector * picosecond detector * laser plasma Subject RIV: BH - Optics, Masers, Lasers Impact factor: 0.415, year: 2008

  18. High quality InAsSb grown on InP substrates using AlSb/AlAsSb buffer layers

    International Nuclear Information System (INIS)

    Wu, B.-R.; Liao, C.; Cheng, K. Y.

    2008-01-01

    High quality InAsSb grown on semi-insulating InP substrates by molecular beam epitaxy was achieved using AlSb/AlAsSb structure as the buffer layer. A 1000 A InAsSb layer grown on top of 1 μm AlSb/AlAsSb buffer layer showed a room temperature electron mobility of ∼12 000 cm 2 /V s. High structural quality and low misfit defect density were also demonstrated in the InAsSb layer. This novel AlSb/AlAsSb buffer layer structure with the AlAsSb layer lattice matched to InP substrates could enhance the performance of optoelectronic devices utilizing 6.1 A family of compound semiconductor alloys

  19. Nitrogen atom transfer mediated by a new PN3P-pincer nickel core via a putative nitrido nickel intermediate

    KAUST Repository

    Yao, Changguang

    2018-02-13

    A 2nd generation PN3P-pincer azido nickel complex (PN3P)Ni(N3) reacts with isocyanides to afford monosubstituted carbodiimides under irradiation, presumably via a transient nitrido intermediate. The resulting species can further generate unsymmetrical carboddimides and the PN3P nickel halide complex, accomplishing a synthetic cycle for a complete nitrogen atom transfer reaction.

  20. Nitrogen atom transfer mediated by a new PN3P-pincer nickel core via a putative nitrido nickel intermediate

    KAUST Repository

    Yao, Changguang; Wang, Xiufang; Huang, Kuo-Wei

    2018-01-01

    A 2nd generation PN3P-pincer azido nickel complex (PN3P)Ni(N3) reacts with isocyanides to afford monosubstituted carbodiimides under irradiation, presumably via a transient nitrido intermediate. The resulting species can further generate unsymmetrical carboddimides and the PN3P nickel halide complex, accomplishing a synthetic cycle for a complete nitrogen atom transfer reaction.

  1. Technology for obtaining of solar elements based on heterostructure basis

    International Nuclear Information System (INIS)

    Camalova, A.Q.; Aliyeva, A.K.; Zeynalova, S.M.; Latifova, N.A.

    2013-01-01

    As it is known the level of energy sources usage reflects the level of development of civilization and was accepted by all as main factor. Currently, there are mainly oil, coal and natural gas are used as raw material in traditional energy, which leads to formation of environmental problems. They are not endless reserves of traditional energy sources and there is a danger of their extinction in the near future. For that reason, recently, the use of wind, solar, thermal waters and some other natural resources rapidly increased in many countries. The most important place among these natural resources belongs to solar energy. Thus, the amount of solar energy coming into the earth is much more than the amount of energy of oil, gas, coal and uranium reserves in the world taken together. At present the annual production of solar components exceeds 500 MW in the world. Photoelectric stations are silent and do not waste harmful products to the environment. The majority of modern solar cells are made on the basis of a single p-n junction

  2. Naringenin (NAR) and 8-prenylnaringenin (8-PN) reduce the developmental competence of porcine oocytes in vitro

    NARCIS (Netherlands)

    Solak, Kamila A.; Santos, Regiane R.; van den Berg, Martin; Blaauboer, Bas J.; Roelen, Bernard A J; van Duursen, Majorie B M

    2014-01-01

    Flavanones such as naringenin (NAR) and 8-prenylnaringenin (8-PN) are increasingly used as dietary supplements despite scientific concern regarding adverse effects on female reproduction upon excessive intake. In the present study, NAR and 8-PN (0.3-1. μM) significantly affected porcine oocyte

  3. Dynamic SPECT of the brain using a lipophilic technetium-99m complex, PnAO

    DEFF Research Database (Denmark)

    Holm, S; Andersen, A R; Vorstrup, S

    1985-01-01

    m PnAO was injected i.v. as a bolus of 15 to 25 mCi. The distribution was followed over 10-sec intervals using a highly sensitive, rapidly rotating SPECT (Tomomatic 64) and compared to 133Xe flow maps. Upon arrival of the PnAO bolus to the brain, a high uptake was found in brain tissue with high......The lipophilic 99mTc-labeled oxime propylene amine oxime (PnAO) should, according to recent reports behave like 133Xe in the human brain. This study compares SPECT images of the two tracers in six subjects: four stroke cases, one transitory ischemic attack case and one normal subject. Technetium-99......AO has a high yet incomplete brain extraction yielding a flow dominated initial distribution with limitations mentioned....

  4. Design review of the Brazilian Experimental Solar Telescope

    Science.gov (United States)

    Dal Lago, A.; Vieira, L. E. A.; Albuquerque, B.; Castilho, B.; Guarnieri, F. L.; Cardoso, F. R.; Guerrero, G.; Rodríguez, J. M.; Santos, J.; Costa, J. E. R.; Palacios, J.; da Silva, L.; Alves, L. R.; Costa, L. L.; Sampaio, M.; Dias Silveira, M. V.; Domingues, M. O.; Rockenbach, M.; Aquino, M. C. O.; Soares, M. C. R.; Barbosa, M. J.; Mendes, O., Jr.; Jauer, P. R.; Branco, R.; Dallaqua, R.; Stekel, T. R. C.; Pinto, T. S. N.; Menconi, V. E.; Souza, V. M. C. E. S.; Gonzalez, W.; Rigozo, N.

    2015-12-01

    The Brazilian's National Institute for Space Research (INPE), in collaboration with the Engineering School of Lorena/University of São Paulo (EEL/USP), the Federal University of Minas Gerais (UFMG), and the Brazilian's National Laboratory for Astrophysics (LNA), is developing a solar vector magnetograph and visible-light imager to study solar processes through observations of the solar surface magnetic field. The Brazilian Experimental Solar Telescope is designed to obtain full disk magnetic field and line-of-sight velocity observations in the photosphere. Here we discuss the system requirements and the first design review of the instrument. The instrument is composed by a Ritchey-Chrétien telescope with a 500 mm aperture and 4000 mm focal length. LCD polarization modulators will be employed for the polarization analysis and a tuning Fabry-Perot filter for the wavelength scanning near the Fe II 630.25 nm line. Two large field-of-view, high-resolution 5.5 megapixel sCMOS cameras will be employed as sensors. Additionally, we describe the project management and system engineering approaches employed in this project. As the magnetic field anchored at the solar surface produces most of the structures and energetic events in the upper solar atmosphere and significantly influences the heliosphere, the development of this instrument plays an important role in advancing scientific knowledge in this field. In particular, the Brazilian's Space Weather program will benefit most from the development of this technology. We expect that this project will be the starting point to establish a strong research program on Solar Physics in Brazil. Our main aim is to progressively acquire the know-how to build state-of-art solar vector magnetograph and visible-light imagers for space-based platforms.

  5. Monte Carlo investigation of minority electron transport in InP

    International Nuclear Information System (INIS)

    Osman, M.A.; Grubin, H.L.

    1989-01-01

    This paper discusses the investigation of the transport of minority electrons in p-type InP for acceptor doping level of 10 18 cm 3 using Monte Carlo procedures. It is found that the velocity of minority electrons are significantly lower than that of majority electrons for fields below 15 kV/cm and slightly higher at higher fields. The study shows that the interaction between the electrons and majority holes leads to reducing the mobility of electrons from 2000 cm 2 /Vs to 1500 cm 2 /Vs

  6. Wavelength tuning of InAs quantum dots grown on InP (100) by chemical-beam epitaxy

    International Nuclear Information System (INIS)

    Gong, Q.; Noetzel, R.; Veldhoven, P.J. van; Eijkemans, T.J.; Wolter, J.H.

    2004-01-01

    We report on an effective way to continuously tune the emission wavelength of InAs quantum dots (QDs) grown on InP (100) by chemical-beam epitaxy. The InAs QD layer is embedded in a GaInAsP layer lattice matched to InP. With an ultrathin GaAs layer inserted between the InAs QD layer and the GaInAsP buffer, the peak wavelength from the InAs QDs can be continuously tuned from above 1.6 μm down to 1.5 μm at room temperature. The major role of the thin GaAs layer is to greatly suppress the As/P exchange during the deposition of InAs and subsequent growth interruption under arsenic flux, as well as to consume the segregated surface In layer floating on the GaInAsP buffer layer

  7. Quantifying losses and thermodynamic limits in nanophotonic solar cells

    Science.gov (United States)

    Mann, Sander A.; Oener, Sebastian Z.; Cavalli, Alessandro; Haverkort, Jos E. M.; Bakkers, Erik P. A. M.; Garnett, Erik C.

    2016-12-01

    Nanophotonic engineering shows great potential for photovoltaics: the record conversion efficiencies of nanowire solar cells are increasing rapidly and the record open-circuit voltages are becoming comparable to the records for planar equivalents. Furthermore, it has been suggested that certain nanophotonic effects can reduce costs and increase efficiencies with respect to planar solar cells. These effects are particularly pronounced in single-nanowire devices, where two out of the three dimensions are subwavelength. Single-nanowire devices thus provide an ideal platform to study how nanophotonics affects photovoltaics. However, for these devices the standard definition of power conversion efficiency no longer applies, because the nanowire can absorb light from an area much larger than its own size. Additionally, the thermodynamic limit on the photovoltage is unknown a priori and may be very different from that of a planar solar cell. This complicates the characterization and optimization of these devices. Here, we analyse an InP single-nanowire solar cell using intrinsic metrics to place its performance on an absolute thermodynamic scale and pinpoint performance loss mechanisms. To determine these metrics we have developed an integrating sphere microscopy set-up that enables simultaneous and spatially resolved quantitative absorption, internal quantum efficiency (IQE) and photoluminescence quantum yield (PLQY) measurements. For our record single-nanowire solar cell, we measure a photocurrent collection efficiency of >90% and an open-circuit voltage of 850 mV, which is 73% of the thermodynamic limit (1.16 V).

  8. Changes of surface electron states of InP under soft X-rays irradiation

    International Nuclear Information System (INIS)

    Yang Zhian; Yang Zushen; Jin Tao; Qui Rexi; Cui Mingqi; Liu Fengqin

    1999-01-01

    Changes of surface electronic states of InP under 1 keV X-ray irradiation is studied by X-ray photoelectron spectroscopy (XPS) and ultraviolet ray energy spectroscopy (UPS). The results show that the soft X-ray irradiation has little effect on In atoms but much on P atoms. The authors analysed the mechanism of irradiation and explained the major effect

  9. Fabrication and Photovoltaic Characteristics of Coaxial Silicon Nanowire Solar Cells Prepared by Wet Chemical Etching

    Directory of Open Access Journals (Sweden)

    Chien-Wei Liu

    2012-01-01

    Full Text Available Nanostructured solar cells with coaxial p-n junction structures have strong potential to enhance the performances of the silicon-based solar cells. This study demonstrates a radial junction silicon nanowire (RJSNW solar cell that was fabricated simply and at low cost using wet chemical etching. Experimental results reveal that the reflectance of the silicon nanowires (SNWs declines as their length increases. The excellent light trapping was mainly associated with high aspect ratio of the SNW arrays. A conversion efficiency of ∼7.1% and an external quantum efficiency of ∼64.6% at 700 nm were demonstrated. Control of etching time and diffusion conditions holds great promise for the development of future RJSNW solar cells. Improving the electrode/RJSNW contact will promote the collection of carries in coaxial core-shell SNW array solar cells.

  10. Visualizing the photovoltaic behavior of a type-II p-n heterojunction superstructure

    Energy Technology Data Exchange (ETDEWEB)

    Xing, Juanjuan, E-mail: xingjuanjuan@mail.sic.ac.cn [State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, 1295 Dingxi Road, Shanghai 200050 (China); Electron Microscopy Group, Surface Physics and Structure Unit, National Institute for Materials Science, 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047 (Japan); Takeguchi, Masaki [Electron Microscopy Group, Surface Physics and Structure Unit, National Institute for Materials Science, 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047 (Japan); Hashimoto, Ayako [Electron Microscopy Group, Surface Physics and Structure Unit, National Institute for Materials Science, 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047 (Japan); Global Research Center for Environment and Energy Based on Nanomaterials Science, 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047 (Japan); Cao, Junyu; Ye, Jinhua [International Center for Materials Nanoarchitectonics (WPI-MANA), 1-1 Namiki, Tsukuba, Ibaraki 305-0044 (Japan)

    2014-04-21

    Photovoltaic behavior of a CaFe{sub 2}O{sub 4}/ZnFe{sub 2}O{sub 4} p-n multi-junction was investigated with electron holography combined with an in situ light irradiation system. Potential profiles of the samples with and without light irradiation were extracted to measure the open circuit photovoltage generated either by the whole heterojunction superstructure or from each p-n junction. Investigation on the variation in the energy band configuration under light irradiation revealed the mechanism involved in the photoelectric effect, with respect to the properties of the heterojunction and its periodic quantum structure.

  11. P-N semiconductor junctions used as X-ray detectors

    International Nuclear Information System (INIS)

    Pela, C.A.; Bruco, J.L.; Navas, E.A.; Paula, E. de; Guilardi Neto, T.

    1987-01-01

    The current response of some comercial P-N semiconductor junctions in function of X-ray incidency, in 40 to 140 KVp band used in diagnosis was characterized. Some junctions were also exposed to radiation of 80 to 250 KVp used in therapy. (C.G.C.) [pt

  12. Comparative study of porosification in InAs, InP, ZnSe and ZnCdS

    International Nuclear Information System (INIS)

    Monaico, Eduard; Tiginyanu, Ion; Nielsch, Kornelius; Ursaki, Veaceslav; Colibaba, Gleb; Nedeoglo, Dmitrii; Cojocaru, Ala; Foell Helmut

    2013-01-01

    We report on a comparative study of the pore growth during anodization of a narrow-bandgap III-V compound (InAs), a medium-bandgap III-V one (InP) and wide-bandgap II-VI semiconductors (ZnSe and Zn 0,4 Cd 0,6 S). According to the obtained results, the morphology of the porous layers can be controlled by the composition of the electrolyte and the applied electrochemical parameters. It was evidenced that in the narrow bandgap semiconductor InAs it is difficult to control the mechanism of pore growth. Both current line oriented pores and crystallographically oriented pores were produced in the medium-bandgap material InP. The electrochemical nanostructuring of wide-bandgap semiconductors realized in single crystalline high conductivity samples evidenced only current-line oriented pores. This behavior is explained in terms of difference in the values of electronegativity of the constituent atoms and the degree of ionicity. (authors)

  13. Investigation of room-temperature wafer bonded GaInP/GaAs/InGaAsP triple-junction solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Wen-xian; Dai, Pan; Ji, Lian; Tan, Ming; Wu, Yuan-yuan [Key Lab of Nanodevices and Applications, Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences (CAS), Suzhou 215123 (China); Uchida, Shiro [Department of Mechanical Science and Engineering Faculty of Engineering, Chiba Institute of Technology, 2-17-1, Tsudanuma, Narashino, Chiba 275-0016 (Japan); Lu, Shu-long, E-mail: sllu2008@sinano.ac.cn [Key Lab of Nanodevices and Applications, Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences (CAS), Suzhou 215123 (China); Yang, Hui [Key Lab of Nanodevices and Applications, Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences (CAS), Suzhou 215123 (China)

    2016-12-15

    Highlights: • High quality InGaAsP material with a bandgap of 1.0 eV was grown by MBE. • Room-temperature wafer-bonded GaInP/GaAs/InGaAsP SCs were fabricated. • An efficiency of 30.3% of wafer-bonded triple-junction SCs was obtained. - Abstract: We report on the fabrication of III–V compound semiconductor multi-junction solar cells using the room-temperature wafer bonding technique. GaInP/GaAs dual-junction solar cells on GaAs substrate and InGaAsP single junction solar cell on InP substrate were separately grown by all-solid state molecular beam epitaxy (MBE). The two cells were then bonded to a triple-junction solar cell at room-temperature. A conversion efficiency of 30.3% of GaInP/GaAs/InGaAsP wafer-bonded solar cell was obtained at 1-sun condition under the AM1.5G solar simulator. The result suggests that the room-temperature wafer bonding technique and MBE technique have a great potential to improve the performance of multi-junction solar cell.

  14. Peripheral pn production and decay angular distributions in the reaction pi /sup -/p to (pn)p at 12 GeV/c incident momentum

    CERN Document Server

    Ghidini, B; Cantore, A; Di Corato, M; Donald, R A; Eades, John; Edwards, D N; Edwards, M E; French, Bernard R; Fry, J R; Houlden, M A; Mandelli, L; Moebes, J P; Müller, K; Navach, F; Palano, A; Palazzi-Cerrina, C; Paul, E; Picciarelli, V; Renneberg, W; Rühmer, W; Smith, I; Zito, G

    1978-01-01

    The reaction pi /sup -/p to (pn)p/sub s/, where p/sub s/ is a slow proton, was measured at 12 GeV/c incident momentum with the CERN-OMEGA spectrometer. Both antiproton and proton were identified uniquely by electronics information. 1844 events with four-momentum transfer squared in the range 0.13pn) up to 2.5 GeV were obtained. The corresponding cross section in this t range is determined to be sigma =4+or-0.4 mu b. Extrapolating the differential cross section over the whole t range assuming d sigma /dt approximately exp(5.3 t) a cross section of sigma =9.3+or-2.0 mu b is estimated. Comparison is made with data on pi /sup -/p to (pp)n/sub s/ (where n/sub s/ is a slow neutron) in the same t range. (12 refs).

  15. Sulfur as a surface passivation for InP

    Science.gov (United States)

    Iyer, R.; Chang, R. R.; Lile, D. L.

    1988-01-01

    The use of liquid and gas phase sulfur pretreatment of the surface of InP as a way to form a near-ideal passivated surface prior to chemical vapor deposition of SiO2 was investigated. Results of high-frequency and quasi-static capacitance-voltage measurements, as well as enhancement mode insulated gate field-effect transistor (FET) transductance and drain current stability studies, all support the efficacy of this approach for metal-insulator-semiconductor application of this semiconductor. In particular, surface state values in the range of 10 to the 10th to a few 10 to the 11th/sq cm per eV and enhancement mode FET drain current drifts of less than 5 percent over a 12 h test period were measured.

  16. A high conversion-gain Q-band InP DHBT subharmonic mixer using LO frequency doubler

    DEFF Research Database (Denmark)

    Johansen, Tom Keinicke; Vidkjær, Jens; Krozer, Viktor

    2008-01-01

    The paper presents analysis and design of a Q-band subharmonic mixer (SHM) with high conversion gain. The SHM consists of a local oscillator (LO) frequency doubler, RF pre-amplifier, and single-ended mixer. The SHM has been fabricated in a high-speed InP double heterojunction bipolar transistor (...

  17. A Psychometric Evaluation of a Swedish Version of the Positive–Negative Sex-Role Inventory (PN-SRI

    Directory of Open Access Journals (Sweden)

    Therese Rydberg Sterner

    2018-02-01

    Full Text Available The Positive–Negative Sex-Role Inventory (PN-SRI assesses gender identity. The aim of this study was to evaluate the validity and reliability of a Swedish version of the PN-SRI in a population of 70-year-olds within the Gothenburg H70-study in Sweden. The overarching objective of testing the PN-SRI within the H70-study was to evaluate its usability to further study gender identity in large population-based samples of older adults. A total of 1124 individuals participated in the psychometric testing. A sub-sample of these (n = 406 provided a comprehensive survey regarding societal norms on femininity and masculinity. Reliability and validity tests were performed using Cronbach’s Alpha and factor analyses. The Cronbach’s α coefficients (0.734–0.787 indicated a satisfactory level of internal consistency, and the four-factor model (Model 2 fitted the data at an acceptable level (root-mean-square error of approximation, RMSEA = 0.068, standardized root-mean-square residual, SRMR = 0.07. This cross-cultural adaptation of the PN-SRI indicates that it may be applicable in a Swedish research setting comprising older adults. Future research is needed to further test the psychometric properties of this scale. Adding the PN-SRI to population-based studies will contribute to providing a nuanced way of analyzing differences and similarities among men and women.

  18. Field-effect P-N junction

    Science.gov (United States)

    Regan, William; Zettl, Alexander

    2015-05-05

    This disclosure provides systems, methods, and apparatus related to field-effect p-n junctions. In one aspect, a device includes an ohmic contact, a semiconductor layer disposed on the ohmic contact, at least one rectifying contact disposed on the semiconductor layer, a gate including a layer disposed on the at least one rectifying contact and the semiconductor layer and a gate contact disposed on the layer. A lateral width of the rectifying contact is less than a semiconductor depletion width of the semiconductor layer. The gate contact is electrically connected to the ohmic contact to create a self-gating feedback loop that is configured to maintain a gate electric field of the gate.

  19. Seeded growth of InP and InAs quantum rods using indium acetate and myristic acid

    International Nuclear Information System (INIS)

    Shweky, Itzhak; Aharoni, Assaf; Mokari, Taleb; Rothenberg, Eli; Nadler, Moshe; Popov, Inna; Banin, Uri

    2006-01-01

    A synthesis of soluble III-V semiconductor quantum rods using gold nanoparticles to direct and catalyze one-dimensional growth is developed. The growth takes place via the solution-liquid-solid (SLS) mechanism where proper precursors are injected into a coordinating solvent. We report the synthesis of InP nanorods using indium acetate and myristic acid with gold nanoparticles as the catalysts in the SLS growth mode. A similar route was successfully developed for the growth of InAs nanorods. We find that the amount of Au catalyst in the reaction is an important parameter to achieve shape control. Transmission electron microscope (TEM) images of InP and InAs nanocrystals revealed that the crystals are mostly rod-shaped, and provide strong evidence for Au presence in one edge. The rods were characterized structurally using X-ray diffraction and high-resolution TEM and optically by absorption and photoluminescence

  20. Optimum third harmonic generation efficiency in the far infrared in Si, GaAs and InP

    International Nuclear Information System (INIS)

    Brazis, R.; Raguotis, R.; Siegrist, M.R.

    1997-12-01

    We investigate by means of a Monte Carlo technique the nonlinear drift response of electrons to high power electromagnetic waves in Si, GaAs and InP. The first and third harmonic drift velocity amplitudes and phases are presented as function of the pumping wave frequency in the range of 200 to 500 GHz. The third harmonic generation efficiency is found to reach a maximum at a pumping wave amplitude of 10-25 kV/cm depending on the material and the lattice temperature. Cooling down to liquid nitrogen temperature results in an improvement of the efficiency by a factor of 2 to 10, depending on the material and the pumping wave amplitude. Cooled GaAs and InP are both an order of magnitude more efficient than Si at ambient temperature, for which to date the best measured performance has been reported. (author) 2 figs., 5 refs