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Sample records for p-type semiconductor material

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

    KAUST Repository

    Wang, Zhenwei

    2016-02-16

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

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

    Science.gov (United States)

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

    2016-05-01

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

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

    Science.gov (United States)

    Welch, James D.

    2000-01-01

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

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

    Science.gov (United States)

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

    2013-08-20

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

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

    Science.gov (United States)

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

    2015-09-21

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

  6. (Ga,Fe)Sb: A p-type ferromagnetic semiconductor

    Energy Technology Data Exchange (ETDEWEB)

    Tu, Nguyen Thanh; Anh, Le Duc; Tanaka, Masaaki [Department of Electrical Engineering and Information Systems, The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-8656 (Japan); Hai, Pham Nam [Department of Electrical Engineering and Information Systems, The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-8656 (Japan); Department of Physical Electronics, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro, Tokyo 152-0033 (Japan)

    2014-09-29

    A p-type ferromagnetic semiconductor (Ga{sub 1−x},Fe{sub x})Sb (x = 3.9%–13.7%) has been grown by low-temperature molecular beam epitaxy (MBE) on GaAs(001) substrates. Reflection high energy electron diffraction patterns during the MBE growth and X-ray diffraction spectra indicate that (Ga,Fe)Sb layers have the zinc-blende crystal structure without any other crystallographic phase of precipitates. Magnetic circular dichroism (MCD) spectroscopy characterizations indicate that (Ga,Fe)Sb has the zinc-blende band structure with spin-splitting induced by s,p-d exchange interactions. The magnetic field dependence of the MCD intensity and anomalous Hall resistance of (Ga,Fe)Sb show clear hysteresis, demonstrating the presence of ferromagnetic order. The Curie temperature (T{sub C}) increases with increasing x and reaches 140 K at x = 13.7%. The crystal structure analyses, magneto-transport, and magneto-optical properties indicate that (Ga,Fe)Sb is an intrinsic ferromagnetic semiconductor.

  7. Nanostructured p-Type Semiconductor Electrodes and Photoelectrochemistry of Their Reduction Processes

    Directory of Open Access Journals (Sweden)

    Matteo Bonomo

    2016-05-01

    Full Text Available This review reports the properties of p-type semiconductors with nanostructured features employed as photocathodes in photoelectrochemical cells (PECs. Light absorption is crucial for the activation of the reduction processes occurring at the p-type electrode either in the pristine or in a modified/sensitized state. Beside thermodynamics, the kinetics of the electron transfer (ET process from photocathode to a redox shuttle in the oxidized form are also crucial since the flow of electrons will take place correctly if the ET rate will overcome that one of recombination and trapping events which impede the charge separation produced by the absorption of light. Depending on the nature of the chromophore, i.e., if the semiconductor itself or the chemisorbed dye-sensitizer, different energy levels will be involved in the cathodic ET process. An analysis of the general properties and requirements of electrodic materials of p-type for being efficient photoelectrocatalysts of reduction processes in dye-sensitized solar cells (DSC will be given. The working principle of p-type DSCs will be described and extended to other p-type PECs conceived and developed for the conversion of the solar radiation into chemical products of energetic/chemical interest like non fossil fuels or derivatives of carbon dioxide.

  8. Inorganic p-Type Semiconductors: Their Applications and Progress in Dye-Sensitized Solar Cells and Perovskite Solar Cells

    Directory of Open Access Journals (Sweden)

    Ming-Hsien Li

    2016-04-01

    Full Text Available Considering the increasing global demand for energy and the harmful ecological impact of conventional energy sources, it is obvious that development of clean and renewable energy is a necessity. Since the Sun is our only external energy source, harnessing its energy, which is clean, non-hazardous and infinite, satisfies the main objectives of all alternative energy strategies. With attractive features, i.e., good performance, low-cost potential, simple processibility, a wide range of applications from portable power generation to power-windows, photoelectrochemical solar cells like dye-sensitized solar cells (DSCs represent one of the promising methods for future large-scale power production directly from sunlight. While the sensitization of n-type semiconductors (n-SC has been intensively studied, the use of p-type semiconductor (p-SC, e.g., the sensitization of wide bandgap p-SC and hole transport materials with p-SC have also been attracting great attention. Recently, it has been proved that the p-type inorganic semiconductor as a charge selective material or a charge transport material in organometallic lead halide perovskite solar cells (PSCs shows a significant impact on solar cell performance. Therefore the study of p-type semiconductors is important to rationally design efficient DSCs and PSCs. In this review, recent published works on p-type DSCs and PSCs incorporated with an inorganic p-type semiconductor and our perspectives on this topic are discussed.

  9. Prediction and theoretical characterization of p-type organic semiconductor crystals for field-effect transistor applications.

    Science.gov (United States)

    Atahan-Evrenk, Sule; Aspuru-Guzik, Alán

    2014-01-01

    The theoretical prediction and characterization of the solid-state structure of organic semiconductors has tremendous potential for the discovery of new high performance materials. To date, the theoretical analysis mostly relied on the availability of crystal structures obtained through X-ray diffraction. However, the theoretical prediction of the crystal structures of organic semiconductor molecules remains a challenge. This review highlights some of the recent advances in the determination of structure-property relationships of the known organic semiconductor single-crystals and summarizes a few available studies on the prediction of the crystal structures of p-type organic semiconductors for transistor applications.

  10. A Density Functional Theory Study of Doped Tin Monoxide as a Transparent p-type Semiconductor

    KAUST Repository

    Bianchi Granato, Danilo

    2012-05-01

    In the pursuit of enhancing the electronic properties of transparent p-type semiconductors, this work uses density functional theory to study the effects of doping tin monoxide with nitrogen, antimony, yttrium and lanthanum. An overview of the theoretical concepts and a detailed description of the methods employed are given, including a discussion about the correction scheme for charged defects proposed by Freysoldt and others [Freysoldt 2009]. Analysis of the formation energies of the defects points out that nitrogen substitutes an oxygen atom and does not provide charge carriers. On the other hand, antimony, yttrium, and lanthanum substitute a tin atom and donate n-type carriers. Study of the band structure and density of states indicates that yttrium and lanthanum improves the hole mobility. Present results are in good agreement with available experimental works and help to improve the understanding on how to engineer transparent p-type materials with higher hole mobilities.

  11. New photovoltaic devices based on the sensitization of p-type semiconductors: challenges and opportunities.

    Science.gov (United States)

    Odobel, Fabrice; Le Pleux, Loïc; Pellegrin, Yann; Blart, Errol

    2010-08-17

    Because solar energy is the most abundant renewable energy resource, the clear connection between human activity and global warming has strengthened the interest in photovoltaic science. Dye-sensitized solar cells (DSSCs) provide a promising low-cost technology for harnessing this energy source. Until recently, much of the research surrounding DSSCs had been focused on the sensitization of n-type semiconductors, such as titanium dioxide (Gratzel cells). In an n-type dye-sensitized solar cell (n-DSSC), an electron is injected into the conduction band of an n-type semiconductor (n-SC) from the excited state of the sensitizer. Comparatively few studies have examined the sensitization of wide bandgap p-type semiconductors. In a p-type DSSC (p-DSSC), the photoexcited sensitizer is reductively quenched by hole injection into the valence band of a p-type semiconductor (p-SC). The study of p-DSSCs is important both to understand the factors that control the rate of hole photoinjection and to aid the rational design of efficient p-DSSCs. In theory, p-DSSCs should be able to work as efficiently as n-DSSCs. In addition, this research provides a method for preparing tandem DSSCs consisting of a TiO(2)-photosensitized anode and a photosensitized p-type SC as a cathode. Tandem DSSCs are particularly important because they represent low-cost photovoltaic devices whose photoconversion efficiencies could exceed 15%. This Account describes recent research results on p-DSSCs. Because these photoelectrochemical devices are the mirror images of conventional n-DSSCs, they share some structural similarities, but they use different materials and have different charge transfer kinetics. In this technology, nickel oxide is the predominant p-SC material used, but much higher photoconversion efficiencies could be achieved with new p-SCs materials with deeper valence band potential. Currently, iodide/triiodide is the main redox mediator of electron transport within these devices, but we expect

  12. Methods for enhancing P-type doping in III-V semiconductor films

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Feng; Stringfellow, Gerald; Zhu, Junyi

    2017-08-01

    Methods of doping a semiconductor film are provided. The methods comprise epitaxially growing the III-V semiconductor film in the presence of a dopant, a surfactant capable of acting as an electron reservoir, and hydrogen, under conditions that promote the formation of a III-V semiconductor film doped with the p-type dopant. In some embodiments of the methods, the epitaxial growth of the doped III-V semiconductor film is initiated at a first hydrogen partial pressure which is increased to a second hydrogen partial pressure during the epitaxial growth process.

  13. Transparent p-type SnO nanowires with unprecedented hole mobility among oxide semiconductors

    KAUST Repository

    Caraveo-Frescas, J. A.

    2013-11-25

    p-type tin monoxide (SnO) nanowire field-effect transistors with stable enhancement mode behavior and record performance are demonstrated at 160 °C. The nanowire transistors exhibit the highest field-effect hole mobility (10.83 cm2 V−1 s−1) of any p-type oxide semiconductor processed at similar temperature. Compared to thin film transistors, the SnO nanowire transistors exhibit five times higher mobility and one order of magnitude lower subthreshold swing. The SnO nanowire transistors show three times lower threshold voltages (−1 V) than the best reported SnO thin film transistors and fifteen times smaller than p-type Cu 2O nanowire transistors. Gate dielectric and process temperature are critical to achieving such performance.

  14. Wide bandgap n-type and p-type semiconductor porous junction devices as photovoltaic cells

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Yuan-Pai; Horng, Sheng-Fu [Institute of Electronics Engineering, National Tsing Hua University, Hsinchu 300, Taiwan (China); Chao, Yu-Chiang; Meng, Hsin-Fei [Institute of Physics, National Chiao Tung University, Hsinchu 300, Taiwan (China); Zan, Hsiao-Wen, E-mail: yuchiangchao@gmail.com, E-mail: meng@mail.nctu.edu.tw [Department of Photonics and Institute of Electro-Optical Engineering, National Chiao Tung University, Hsinchu 300, Taiwan (China)

    2011-10-12

    In junction absorber photovoltaics doped wide bandgap n-type and p-type semiconductors form a porous interpenetrating junction structure with a layer of low bandgap absorber at the interface. The doping concentration is high enough such that the junction depletion width is smaller than the pore size. The highly conductive neutral region then has a dentrite shape with fingers reaching the absorber to effectively collect the photo-carriers swept out by the junction electric field. With doping of 10{sup 19} cm{sup -3} corresponding to a depletion width of 25 nm, pore size of 32 nm, absorber thickness close to exciton diffusion length of 17 nm, absorber bandgap of 1.4 eV and carrier mobility over 10{sup -5} cm{sup 2} V{sup -1} s{sup -1}, numerical calculation shows the power conversion efficiency is as high as 19.4%. It rises to 23% for a triplet exciton absorber.

  15. Semiconductor surface protection material

    Science.gov (United States)

    Packard, R. D. (Inventor)

    1973-01-01

    A method and a product for protecting semiconductor surfaces is disclosed. The protective coating material is prepared by heating a suitable protective resin with an organic solvent which is solid at room temperature and converting the resulting solution into sheets by a conventional casting operation. Pieces of such sheets of suitable shape and thickness are placed on the semiconductor areas to be coated and heat and vacuum are then applied to melt the sheet and to drive off the solvent and cure the resin. A uniform adherent coating, free of bubbles and other defects, is thus obtained exactly where it is desired.

  16. P-type thin films transistors with solution-deposited lead sulfide films as semiconductor

    Energy Technology Data Exchange (ETDEWEB)

    Carrillo-Castillo, A.; Salas-Villasenor, A.; Mejia, I. [Department of Materials Science and Engineering, The University of Texas at Dallas. 800 West Campbell Rd, Richardson, TX 75083 (United States); Aguirre-Tostado, S. [Centro de Investigacion en Materiales Avanzados, S. C. Alianza Norte 202, Parque de Investigacion e Innovacion Tecnologica, Apodaca, Nuevo Leon, C.P. 666000 (Mexico); Gnade, B.E. [Department of Materials Science and Engineering, University of Texas at Dallas. 800 West Campbell Rd, Richardson, TX 75083 (United States); Quevedo-Lopez, M.A., E-mail: mxq071000@utdallas.edu [Department of Materials Science and Engineering, University of Texas at Dallas. 800 West Campbell Rd, Richardson, TX 75083 (United States)

    2012-01-31

    In this paper we demonstrate p-type thin film transistors fabricated with lead sulfide (PbS) as semiconductor deposited by chemical bath deposition methods. Crystallinity and morphology of the resulting PbS films were characterized using X-ray diffraction, atomic force microscopy and scanning electron microscopy. Devices were fabricated using photolithographic processes in a bottom gate configuration with Au as source and drain top contacts. Field effect mobility for as-fabricated devices was {approx} 0.09 cm{sup 2} V{sup -1} s{sup -1} whereas the mobility for devices annealed at 150 Degree-Sign C/h in forming gas increased up to {approx} 0.14 cm{sup 2} V{sup -1} s{sup -1}. Besides the thermal annealing, the entire fabrications process was maintained below 100 Degree-Sign C. The electrical performance of the PbS-thin film transistors was studied before and after the 150 Degree-Sign C anneal as well as a function of the PbS active layer thicknesses. - Highlights: Black-Right-Pointing-Pointer Thin film transistors with PbS as semiconductor deposited by chemical bath deposition. Black-Right-Pointing-Pointer Photolithography-based thin film transistors with PbS films at low temperatures. Black-Right-Pointing-Pointer Electron mobility for anneal-PbS devices of {approx} 0.14 cm{sup 2} V{sup -1} s{sup -1}. Black-Right-Pointing-Pointer Highest mobility reported in thin film transistors with PbS as the semiconductor.

  17. Handbook of luminescent semiconductor materials

    CERN Document Server

    Bergman, Leah

    2011-01-01

    Photoluminescence spectroscopy is an important approach for examining the optical interactions in semiconductors and optical devices with the goal of gaining insight into material properties. With contributions from researchers at the forefront of this field, Handbook of Luminescent Semiconductor Materials explores the use of this technique to study semiconductor materials in a variety of applications, including solid-state lighting, solar energy conversion, optical devices, and biological imaging. After introducing basic semiconductor theory and photoluminescence principles, the book focuses

  18. Two-dimensional ferromagnet/semiconductor transition metal dichalcogenide contacts: p-type Schottky barrier and spin-injection control

    KAUST Repository

    Gan, Liyong

    2013-09-26

    We study the ferromagnet/semiconductor contacts formed by transition metal dichalcogenide monolayers, focusing on semiconducting MoS2 and WS2 and ferromagnetic VS2. We investigate the degree of p-type doping and demonstrate tuning of the Schottky barrier height by vertical compressive pressure. An analytical model is presented for the barrier heights that accurately describes the numerical findings and is expected to be of general validity for all transition metal dichalcogenide metal/semiconductor contacts. Furthermore, magnetic proximity effects induce a 100% spin polarization at the Fermi level in the semiconductor where the spin splitting increases up to 0.70 eV for increasing pressure.

  19. Screening of inorganic wide-bandgap p-type semiconductors for high performance hole transport layers in organic photovoltaic devices

    Science.gov (United States)

    Ginley, David; Zakutayev, Andriy; Garcia, Andreas; Widjonarko, Nicodemus; Ndione, Paul; Sigdel, Ajaya; Parilla, Phillip; Olson, Dana; Perkins, John; Berry, Joseph

    2011-03-01

    We will report on the development of novel inorganic hole transport layers (HTL) for organic photovoltaics (OPV). All the studied materials belong to the general class of wide-bandgap p-type oxide semiconductors. Potential candidates suitable for HTL applications include SnO, NiO, Cu2O (and related CuAlO2, CuCrO2, SrCu2O4 etc) and Co3O4 (and related ZnCo2O4, NiCo2O4, MgCo2O4 etc.). Materials have been optimized by high-throughput combinatorial approaches. The thin films were deposited by RF sputtering and pulsed laser deposition at ambient and elevated temperatures. Performance of the inorganic HTLs and that of the reference organic PEDOT:PSS HTL were compared by measuring the power conversion efficiencies and spectral responses of the P3HT/PCBM- and PCDTBT/PCBM-based OPV devices. Preliminary results indicate that Co3O4-based HTLs have performance comparable to that of our previously reported NiOs and PEDOT:PSS HTLs, leading to a power conversion efficiency of about 4 percent. The effect of composition and work function of the ternary materials on their performance in OPV devices is under investigation.

  20. Method for depositing high-quality microcrystalline semiconductor materials

    Science.gov (United States)

    Guha, Subhendu; Yang, Chi C.; Yan, Baojie

    2011-03-08

    A process for the plasma deposition of a layer of a microcrystalline semiconductor material is carried out by energizing a process gas which includes a precursor of the semiconductor material and a diluent with electromagnetic energy so as to create a plasma therefrom. The plasma deposits a layer of the microcrystalline semiconductor material onto the substrate. The concentration of the diluent in the process gas is varied as a function of the thickness of the layer of microcrystalline semiconductor material which has been deposited. Also disclosed is the use of the process for the preparation of an N-I-P type photovoltaic device.

  1. Optical characteristics of p-type GaAs-based semiconductors towards applications in photoemission infrared detectors

    Science.gov (United States)

    Lao, Y. F.; Perera, A. G. U.; Wang, H. L.; Zhao, J. H.; Jin, Y. J.; Zhang, D. H.

    2016-03-01

    Free-carrier effects in a p-type semiconductor including the intra-valence-band and inter-valence-band optical transitions are primarily responsible for its optical characteristics in infrared. Attention has been paid to the inter-valence-band transitions for the development of internal photoemission (IPE) mid-wave infrared (MWIR) photodetectors. The hole transition from the heavy-hole (HH) band to the spin-orbit split-off (SO) band has demonstrated potential applications for 3-5 μm detection without the need of cooling. However, the forbidden SO-HH transition at the Γ point (corresponding to a transition energy Δ0, which is the split-off gap between the HH and SO bands) creates a sharp drop around 3.6 μm in the spectral response of p-type GaAs/AlGaAs detectors. Here, we report a study on the optical characteristics of p-type GaAs-based semiconductors, including compressively strained InGaAs and GaAsSb, and a dilute magnetic semiconductor, GaMnAs. A model-independent fitting algorithm was used to derive the dielectric function from experimental reflection and transmission spectra. Results show that distinct absorption dip at Δ0 is observable in p-type InGaAs and GaAsSb, while GaMnAs displays enhanced absorption without degradation around Δ0. This implies the promise of using GaMnAs to develop MWIR IPE detectors. Discussions on the optical characteristics correlating with the valence-band structure and free-hole effects are presented.

  2. Comparison of ferromagnetism in n- and p-type magnetic semiconductor thin films of ZnCoO

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Y.H., E-mail: yuhua@phys.ncku.edu.t [Department of Physics, National Cheng Kung University, No. 1, Ta-Shuei Road, Tainan 70101, Taiwan (China); Lee, J.C.; Min, J.F. [Department of Physics, National Cheng Kung University, No. 1, Ta-Shuei Road, Tainan 70101, Taiwan (China); Su, C.W. [Department of Applied Physics, National Chiayi University, Chiayi 60004, Taiwan (China)

    2011-07-15

    Both n- and p-type diluted magnetic semiconductor ZnCoO are made by magnetron co-sputtering with, respectively, dopants of Al and dual dopants of Al and N. The two sputtering targets are compound ZnCoO with 5% weight of Co and pure metal Al. Sputtering gases for n- and p-type films are pure Ar and N{sub 2}, respectively. These films are magnetic at room temperature and possess free electron- and hole-concentration of 5.34x10{sup 20} and 5.27x10{sup 13} cm{sup -3}. Only the n-type film exhibits anomalous Hall-effect signals. Magnetic properties of these two types of films are compared and discussed based on measurements of microstructure and magneto-transport properties. - Research highlights: n-type ZnCoO:Al and p-type ZnCoO:(Al, N) films are made and are both ferromagnetic at room temperature. Signal of anomalous Hall-effect (AHE) is clearly observed only for n-type film but not for p-type film. Photoluminescence (PL) spectrum shows a peak attributed to shallow acceptor band of N. Ferromagnetic exchange coupling between magnetic ions in n-type film is through spin polarized free electrons. Ferromagnetism in p-type film is not attributed to the free hole-carriers mediation but to the overlap of BMP.

  3. Selective growth of n-type nanoparticles on p-type semiconductors for Z-scheme photocatalysis.

    Science.gov (United States)

    Miyauchi, Masahiro; Nukui, Yuuya; Atarashi, Daiki; Sakai, Etsuo

    2013-10-09

    Nanoparticles of an n-type WO3 semiconductor were segregated on the surface of p-type CaFe2O4 particles by a heterogeneous nucleation process under controlled hydrothermal conditions. By use of this approach, WO3 nanoparticles were selectively deposited on the surface of CaFe2O4, resulting in a significant increase in the photocatalytic reaction rate of the WO3/CaFe2O4 composite for the decomposition of gaseous acetaldehyde under visible-light irradiation. The high visible-light activity of the WO3/CaFe2O4 composite was due to efficient charge recombination through the junctions that formed between the two semiconductors.

  4. Application of neutron transmutation doping method to initially p-type silicon material.

    Science.gov (United States)

    Kim, Myong-Seop; Kang, Ki-Doo; Park, Sang-Jun

    2009-01-01

    The neutron transmutation doping (NTD) method was applied to the initially p-type silicon in order to extend the NTD applications at HANARO. The relationship between the irradiation neutron fluence and the final resistivity of the initially p-type silicon material was investigated. The proportional constant between the neutron fluence and the resistivity was determined to be 2.3473x10(19)nOmegacm(-1). The deviation of the final resistivity from the target for almost all the irradiation results of the initially p-type silicon ingots was at a range from -5% to 2%. In addition, the burn-up effect of the boron impurities, the residual (32)P activity and the effect of the compensation characteristics for the initially p-type silicon were studied. Conclusively, the practical methodology to perform the neutron transmutation doping of the initially p-type silicon ingot was established.

  5. Semiconductor packaging materials interaction and reliability

    CERN Document Server

    Chen, Andrea

    2012-01-01

    In semiconductor manufacturing, understanding how various materials behave and interact is critical to making a reliable and robust semiconductor package. Semiconductor Packaging: Materials Interaction and Reliability provides a fundamental understanding of the underlying physical properties of the materials used in a semiconductor package. The book focuses on an important step in semiconductor manufacturing--package assembly and testing. It covers the basics of material properties and explains how to determine which behaviors are important to package performance. The authors also discuss how

  6. The processing of semiconductor materials

    Science.gov (United States)

    1979-01-01

    Five experiments involving the processing of semiconductor materials were performed during the Skylab mission. After discussions on semiconductors and their unique electronic properties, and techniques of crystal growth, these five experiments are presented. Four melt growth experiments were attempted: (1) steady state growth and segregation under zero gravity (InSb); (2) seeded, containerless solidification of InSb; (3) influence of gravity-free solidification on microsegregation; and (4) directional solidification of InSb-GaSb alloys. One vapor growth experiment, crystal growth by vapor transport, was attempted.

  7. A theoretical description of charge reorganization energies in molecular organic P-type semiconductors.

    Science.gov (United States)

    Brückner, Charlotte; Engels, Bernd

    2016-06-05

    Charge transport properties of materials composed of small organic molecules are important for numerous optoelectronic applications. A material's ability to transport charges is considerably influenced by the charge reorganization energies of the composing molecules. Hence, predictions about charge-transport properties of organic materials deserve reliable statements about these charge reorganization energies. However, using density functional theory which is mostly used for the predictions, the computed reorganization energies depend strongly on the chosen functional. To gain insight, a benchmark of various density functionals for the accurate calculation of charge reorganization energies is presented. A correlation between the charge reorganization energies and the ionization potentials is found which suggests applying IP-tuning to obtain reliable values for charge reorganization energies. According to benchmark investigations with IP-EOM-CCSD single-point calculations, the tuned functionals provide indeed more reliable charge reorganization energies. Among the standard functionals, ωB97X-D and SOGGA11X yield accurate charge reorganization energies in comparison with IP-EOM-CCSD values. © 2016 Wiley Periodicals, Inc.

  8. Novel p-Type Conductive Semiconductor Nanocrystalline Film as the Back Electrode for High-Performance Thin Film Solar Cells.

    Science.gov (United States)

    Zhang, Ming-Jian; Lin, Qinxian; Yang, Xiaoyang; Mei, Zongwei; Liang, Jun; Lin, Yuan; Pan, Feng

    2016-02-10

    Thin film solar cells, due to the low cost, high efficiency, long-term stability, and consumer applications, have been widely applied for harvesting green energy. All of these thin film solar cells generally adopt various metal thin films as the back electrode, like Mo, Au, Ni, Ag, Al, graphite, and so forth. When they contact with p-type layer, it always produces a Schottky contact with a high contact potential barrier, which greatly affects the cell performance. In this work, we report for the first time to find an appropriate p-type conductive semiconductor film, digenite Cu9S5 nanocrystalline film, as the back electrode for CdTe solar cells as the model device. Its low sheet resistance (16.6 Ω/sq) could compare to that of the commercial TCO films (6-30 Ω/sq), like FTO, ITO, and AZO. Different from the traditonal metal back electrode, it produces a successive gradient-doping region by the controllable Cu diffusion, which greatly reduces the contact potential barrier. Remarkably, it achieved a comparable power conversion efficiency (PCE, 11.3%) with the traditional metal back electrode (Cu/Au thin films, 11.4%) in CdTe cells and a higher PCE (13.8%) with the help of the Au assistant film. We believe it could also act as the back electrode for other thin film solar cells (α-Si, CuInS2, CIGSe, CZTS, etc.), for their performance improvement.

  9. P-type AlAs/[GaAs/AlAs] Semiconductor/Superlattice DBR Grown by MBE

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    A p-type AlAs(70.2 nm)/16.5 period [GaAs(3 nm)/AlAs(0.7 nm)] semiconductor/superlatice distributed Bragg reflector (DBR) has been grown on n+-GaAs(100) substrate by V80H molecular beam epitaxy system. Experimental reflection spectrum shows that its central wavelength is 820 nm, with the peak reflectivity for 10-pair DBR of as high as 96 %, and the reflection bandwidth of as wide as 90 nm. We formed a 20×20 μm2 square mesa to measure the series resistance using wet chemical etching. From the measurement result, the series resistance of about 50 Ω is obtained at a moderate doping (3×1018 cm-3). Finally, the dependence of the resistance of the DBR on the temperature is analyzed. From the experimental result, it is found that the mechanism of the low series resistance of this kind of DBR may increase the tunneling current in the semiconductor/superlattice mirror structure, which will result in a decrease in series resistance.

  10. Fundamentals of semiconductors physics and materials properties

    CERN Document Server

    Yu, Peter Y

    2005-01-01

    Provides detailed explanations of the electronic, vibrational, transport, and optical properties of semiconductors. This textbook emphasizes understanding the physical properties of Si and similar tetrahedrally coordinated semiconductors and features an extensive collection of tables of material parameters, figures, and problems.

  11. Interaction of cochlear nucleus explants with semiconductor materials.

    Science.gov (United States)

    Mlynski, Robert; Volkenstein, Stefan; Hansen, Stefan; Brors, Dominik; Ebmeyer, Joerg; Dazert, Stefan

    2007-07-01

    Implantable hearing devices such as cochlear implants and auditory brainstem implants deliver auditory information through electrical stimulation of auditory neurons. The combination of microelectronic electrodes with auditory nerve cells may lead to further improvement of the hearing quality with these devices. Whereas several kinds of neurons are known to grow on semiconductor substrates, interactions of cochlear nucleus (CN) neurons with such materials have yet to be described. To investigate survival and growth behavior of CN neurons on different semiconductor materials. CN explants from postnatal day 10 Sprague-Dawley rats were cultured for 96 hours in Neurobasal medium on polished and unpolished silicon wafers (p-type Si [100] and p-type Si3N4[100]) as well as plastic surface. These surfaces had been coated with poly-L-lysine and laminin. Neuronal outgrowth was examined using image analysis software after immunohistologic staining for neurofilament. Neurite length and directional changes were quantified. Additionally, neurite morphology and adhesion to the semiconductor material was evaluated by scanning electron microscopy. Although proper adhesion of CN explants was seen, no neurite growth could be detected on unpolished silicon wafers (Si and Si3N4). Compared with the other test conditions, polished, laminin-coated Si3N4 wafers showed best biocompatibility regarding neurite length and number per explant. CN explants developed a mean of eight neurons with an average length of 236 mum in 96 hours of culture on these wafers. The results of this study demonstrate the general possibility of CN neuron growth in culture on semiconductors in vitro. The differences in neuron length and number per explant indicate that the growth of CN neurons is influenced by the semiconductor substrate as well as extracellular matrix proteins, with laminin-coated p-type Si3N4[100] being a preferable material for future hybrid experiments on auditory-neuron semiconductor chips.

  12. Trace analysis of semiconductor materials

    CERN Document Server

    Cali, J Paul; Gordon, L

    1964-01-01

    Trace Analysis of Semiconductor Materials is a guidebook concerned with procedures of ultra-trace analysis. This book discusses six distinct techniques of trace analysis. These techniques are the most common and can be applied to various problems compared to other methods. Each of the four chapters basically includes an introduction to the principles and general statements. The theoretical basis for the technique involved is then briefly discussed. Practical applications of the techniques and the different instrumentations are explained. Then, the applications to trace analysis as pertaining

  13. Rhodium-doped barium titanate perovskite as a stable p-type semiconductor photocatalyst for hydrogen evolution under visible light.

    Science.gov (United States)

    Maeda, Kazuhiko

    2014-02-12

    Rhodium-doped barium titanate (BaTiO3:Rh) powder was prepared by the polymerized complex (PC) method, and the photocatalytic activity for H2 evolution from water was examined. BaTiO3 is a wide-gap n-type semiconductor having a band gap of 3.0 eV. Doping Rh species into the lattice of BaTiO3 resulted in the formation of new absorption bands in visible light region. Upon visible light (λ > 420 nm), BaTiO3:Rh modified with nanoparticulate Pt as a water reduction promoter was capable of producing H2 from water containing an electron donor such as methanol and iodide. The best material prepared by the PC method exhibited higher activity than that made by a conventional solid-state reaction method. Visible-light-driven Z-scheme water splitting was also accomplished using Pt/BaTiO3:Rh as a building block for H2 evolution in combination with PtOx-loaded WO3 as an O2 evolution photocatalyst in the presence of an IO3(-)/I(-) shuttle redox mediator. Photoelectrochemical analysis indicated that a porous BaTiO3:Rh electrode exhibited cathodic photoresponse due to water reduction in a neutral aqueous Na2SO4 solution upon visible light.

  14. Semiconductor device PN junction fabrication using optical processing of amorphous semiconductor material

    Science.gov (United States)

    Sopori, Bhushan; Rangappan, Anikara

    2014-11-25

    Systems and methods for semiconductor device PN junction fabrication are provided. In one embodiment, a method for fabricating an electrical device having a P-N junction comprises: depositing a layer of amorphous semiconductor material onto a crystalline semiconductor base, wherein the crystalline semiconductor base comprises a crystalline phase of a same semiconductor as the amorphous layer; and growing the layer of amorphous semiconductor material into a layer of crystalline semiconductor material that is epitaxially matched to the lattice structure of the crystalline semiconductor base by applying an optical energy that penetrates at least the amorphous semiconductor material.

  15. High throughput combinatorial screening of semiconductor materials

    Science.gov (United States)

    Mao, Samuel S.

    2011-11-01

    This article provides an overview of an advanced combinatorial material discovery platform developed recently for screening semiconductor materials with properties that may have applications ranging from radiation detectors to solar cells. Semiconductor thin-film libraries, each consisting of 256 materials of different composition arranged into a 16×16 matrix, were fabricated using laser-assisted evaporation process along with a combinatorial mechanism to achieve variations. The composition and microstructure of individual materials on each thin-film library were characterized with an integrated scanning micro-beam x-ray fluorescence and diffraction system, while the band gaps were determined by scanning optical reflection and transmission of the libraries. An ultrafast ultraviolet photon-induced charge probe was devised to measure the mobility and lifetime of individual thin-film materials on semiconductor libraries. Selected results on the discovery of semiconductors with desired band gaps and transport properties are illustrated.

  16. All-vapor processing of P-type tellurium-containing II-VI semiconductor and ohmic contacts thereof

    Energy Technology Data Exchange (ETDEWEB)

    McCandless, Brian E.

    2000-03-01

    An all dry method for producing solar cells is provided comprising first heat-annealing a II-VI semiconductor; enhancing the conductivity and grain size of the annealed layer; modifying the surface and depositing a tellurium layer onto the enhanced layer; and then depositing copper onto the tellurium layer so as to produce a copper tellurium compound on the layer.

  17. Back-side readout semiconductor photomultiplier

    Science.gov (United States)

    Choong, Woon-Seng; Holland, Stephen E

    2014-05-20

    This disclosure provides systems, methods, and apparatus related to semiconductor photomultipliers. In one aspect, a device includes a p-type semiconductor substrate, the p-type semiconductor substrate having a first side and a second side, the first side of the p-type semiconductor substrate defining a recess, and the second side of the p-type semiconductor substrate being doped with n-type ions. A conductive material is disposed in the recess. A p-type epitaxial layer is disposed on the second side of the p-type semiconductor substrate. The p-type epitaxial layer includes a first region proximate the p-type semiconductor substrate, the first region being implanted with p-type ions at a higher doping level than the p-type epitaxial layer, and a second region disposed on the first region, the second region being doped with p-type ions at a higher doping level than the first region.

  18. Controlling the stoichiometry and doping of semiconductor materials

    Science.gov (United States)

    Albin, David; Burst, James; Metzger, Wyatt; Duenow, Joel; Farrell, Stuart; Colegrove, Eric

    2016-08-16

    Methods for treating a semiconductor material are provided. According to an aspect of the invention, the method includes annealing the semiconductor material in the presence of a compound that includes a first element and a second element. The first element provides an overpressure to achieve a desired stoichiometry of the semiconductor material, and the second element provides a dopant to the semiconductor material.

  19. Nitride Semiconductors Handbook on Materials and Devices

    CERN Document Server

    Ruterana, Pierre; Neugebauer, Jörg

    2003-01-01

    Semiconductor components based on silicon have been used in a wide range of applications for some time now. These elemental semiconductors are now well researched and technologically well developed. In the meantime the focus has switched to a new group of materials: ceramic semiconductors based on nitrides are currently the subject of research due to their optical and electronic characteristics. They open up new industrial possibilities in the field of photosensors, as light sources or as electronic components. This collection of review articles provides a systematic and in-depth overview of t

  20. Semiconductor materials for solar photovoltaic cells

    CERN Document Server

    Wong-Ng, Winnie; Bhattacharya, Raghu

    2016-01-01

    This book reviews the current status of semiconductor materials for conversion of sunlight to electricity, and highlights advances in both basic science and manufacturing.  Photovoltaic (PV) solar electric technology will be a significant contributor to world energy supplies when reliable, efficient PV power products are manufactured in large volumes at low cost.  Expert chapters cover the full range of semiconductor materials for solar-to-electricity conversion, from crystalline silicon and amorphous silicon to cadmium telluride, copper indium gallium sulfide selenides, dye sensitized solar cells, organic solar cells, and environmentally friendly copper zinc tin sulfide selenides. The latest methods for synthesis and characterization of solar cell materials are described, together with techniques for measuring solar cell efficiency. Semiconductor Materials for Solar Photovoltaic Cells presents the current state of the art as well as key details about future strategies to increase the efficiency and reduce ...

  1. Scanning probe characterization of novel semiconductor materials and devices

    Science.gov (United States)

    Zhou, Xiaotian

    As semiconductor devices shrink in size, it becomes more important to characterize and understand electronic properties of the materials and devices at the nanoscale. Scanning probe techniques offers numerous advantages over traditional tools used for semiconductor materials and devices characterization including high spatial resolution, ease of use and multi-functionality for electrical characterization, such as current, potential and capacitance, etc. In the first chapter, the basic principle of atomic force microscopy (AFM), and its application to characterization of semiconductor materials and devices are discussed. In the second part of the thesis, scanning capacitance microscopy (SCM), spectroscopy (SCS) and scanning Kelvin probe microscopy (SKPM) are used to investigate the structure and electronic properties of nitride based materials and devices, specifically doping in p-type GaN and electronic structure and morphology of InxGa1-xN/GaN quantum wells. In this work, AFM is used to characterize the local electronic structure in nitride thin film and heterostructures devices. In next part the thesis, AFM is used as an active part of the device, in conductive atomic force microscopy (C-AFM) and scanning gate microscopy (SGM), to study the transport properties and gating effect of InAs semiconductor nanowire based field effect transistor. This is made possible because the nanowire, as a potential one-dimension building block for high performance electronics and optoelectronics, has a diameter comparable to the size of AFM tips. In the last part of the thesis (appendix), SKPM is used to characterize semiconductor-like organic thin films, where measurements of the potential profile along the channel of an organic thin film transistor (OTFT) at different gate bias are presented to illustrate the unique transport property of such devices.

  2. A Novel Sr2CuInO3S p-type semiconductor photocatalyst for hydrogen production under visible light irradiation

    Institute of Scientific and Technical Information of China (English)

    Yushuai Jia; Jingxiu Yang; Dan Zhao; Hongxian Han; Can Li

    2014-01-01

    A novel Sr2CuInO3S oxysulfide p-type semiconductor photocatalyst has been prepared by solid state reaction method and it exhibits intriguing visible light absorption properties with a bandgap of 2.3 eV. The p-type semiconductor character of the synthesized Sr2CuInO3S was confirmed by Hall efficient measurement and Mott-Schottky plot analysis. First-principles density functional theory calculations (DFT) and electrochem-ical measurements were performed to elucidate the electronic structure and the energy band locations. It was found that the as-synthesized Sr2CuInO3S photocatalyst has appreciate conduction and valence band positions for hydrogen and oxygen evolution, respectively. Photocat-alytic hydrogen production experiments under a visible light irradiation (λ>420 nm) were carried out by loading different metal and metal-like cocatalysts on Sr2CuInO3S and Rh was found to be the best one among the tested ones.

  3. Electronic Band Structure and New Magneto-transport Properties in p-type Semiconductor Medium-infrared HgTe / CdTe Superlattice

    Science.gov (United States)

    Nafidi, Ab.; EL Abidi, A.; El Kaaouachi, A.; Nafidi, Ah.

    2005-06-01

    We report here the band structure and new magneto-transport results for HgTe (56 Å) / CdTe (30 Å) superlattice grown by molecular beam epitaxy (MBE). The angular dependence of the transverse magnetoresistance follows the two-dimensional (2D) behaviour. At low temperature, the sample exhibits p type conductivity with a concentration of 1.84×1012 cm-2 and a Hall mobility of 8200 cm2/Vs. The observed Shubnikov-de Haas effect gives a carrier density of 1.80×1012 cm-2. The superlattice heavy holes dominate the conduction in plane with an effective mass of 0.297 m0 and Fermi energy (2D) of 14 meV. In intrinsic regime, the measured gap Eg = 190 meV agree well with calculated Eg(Γ, 300 K) =178 meV. The formalism used here predicts that the system is semiconductor, for our HgTe to CdTe thickness ratio d1/d2 = 1,87, when d2 < 140 Å. In our case, d2=30 Å and Eg (Γ, 4.2 K) = 111 meV. In spite of it, the sample exhibits the features typical of a p type semiconductor and is a medium-infrared detector (7 μm< λ< 11 μm).

  4. Measurements of radioactive contaminants in semiconductor materials

    Science.gov (United States)

    Gordon, Michael S.; Rodbell, Kenneth P.; Murray, Conal E.; McNally, Brendan D.

    2016-12-01

    The emission of alpha particles from materials used to manufacture semiconductors can contribute substantially to the single-event upset rate. The alpha particles originate from contamination in the materials, or from radioactive isotopes, themselves. In this review paper, we discuss the sources of the radioactivity and the measurement methods to detect the emitted particles.

  5. Templated Chemically Deposited Semiconductor Optical Fiber Materials

    Science.gov (United States)

    Sparks, Justin R.; Sazio, Pier J. A.; Gopalan, Venkatraman; Badding, John V.

    2013-07-01

    Chemical deposition is a powerful technology for fabrication of planar microelectronics. Optical fibers are the dominant platform for telecommunications, and devices such as fiber lasers are forming the basis for new industries. High-pressure chemical vapor deposition (HPCVD) allows for conformal layers and void-free wires of precisely doped crystalline unary and compound semiconductors inside the micro-to-nanoscale-diameter pores of microstructured optical fibers (MOFs). Drawing the fibers to serve as templates into which these semiconductor structures can be fabricated allows for geometric design flexibility that is difficult to achieve with planar fabrication. Seamless coupling of semiconductor optoelectronic and photonic devices with existing fiber infrastructure thus becomes possible, facilitating all-fiber technological approaches. The deposition techniques also allow for a wider range of semiconductor materials compositions to be exploited than is possible by means of preform drawing. Gigahertz bandwidth junction-based fiber devices can be fabricated from doped crystalline semiconductors, for example. Deposition of amorphous hydrogenated silicon, which cannot be drawn, allows for the exploitation of strong nonlinear optical function in fibers. Finally, crystalline compound semiconductor fiber cores hold promise for high-power infrared light-guiding fiber devices and subwavelength-resolution, large-area infrared imaging.

  6. Solution-processable low-molecular weight extended arylacetylenes: versatile p-type semiconductors for field-effect transistors and bulk heterojunction solar cells.

    Science.gov (United States)

    Silvestri, Fabio; Marrocchi, Assunta; Seri, Mirko; Kim, Choongik; Marks, Tobin J; Facchetti, Antonio; Taticchi, Aldo

    2010-05-05

    We report the synthesis and characterization of a series of five extended arylacetylenes, 9,10-bis-{[m,p-bis(hexyloxy)phenyl]ethynyl}-anthracene (A-P6t, 1), 9,10-bis-[(p-{[m,p-bis(hexyloxy) phenyl]ethynyl}phenyl)ethynyl]-anthracene (PA-P6t, 2), 4,7-bis-{[m,p-bis(hexyloxy)phenyl]ethynyl}-2,1,3-benzothiadiazole (BTZ-P6t, 5), 4,7-bis(5-{[m,p-bis(hexyloxy)phenyl]ethynyl}thien-2-yl)-2,1,3-benzothiadiazole (TBTZ-P6t, 6), and 7,7'-({[m,p-bis(hexyloxy)phenyl]ethynyl}-2,1,3-benzothiadiazol-4,4'-ethynyl)-2,5-thiophene (BTZT-P6t, 7), and two arylvinylenes, 9,10-bis-{(E)-[m,p-bis(hexyloxy)phenyl]vinyl}-anthracene (A-P6d, 3), 9,10-bis-[(E)-(p-{(E)-[m,p-bis(hexyloxy)phenyl]vinyl}phenyl)vinyl]-anthracene (PA-P6d, 4). Trends in optical absorption spectra and electrochemical redox processes are first described. Next, the thin-film microstructures and morphologies of films deposited from solution under various conditions are investigated, and organic field-effect transistors (OFETs) and bulk heterojunction photovoltaic (OPV) cells fabricated. We find that substituting acetylenic for olefinic linkers on the molecular cores significantly enhances device performance. OFET measurements reveal that all seven of the semiconductors are FET-active and, depending on the backbone architecture, the arylacetylenes exhibit good p-type mobilities (mu up to approximately 0.1 cm(2) V(-1) s(-1)) when optimum film microstructural order is achieved. OPV cells using [6,6]-phenyl C(61)-butyric acid methyl ester (PCBM) as the electron acceptor exhibit power conversion efficiencies (PCEs) up to 1.3% under a simulated AM 1.5 solar irradiation of 100 mW/cm(2). These results demonstrate that arylacetylenes are promising hole-transport materials for p-channel OFETs and promising donors for organic solar cells applications. A direct correlation between OFET arylacetylene hole mobility and OPV performance is identified and analyzed.

  7. p-Type Transparent Conducting Oxide/n-Type Semiconductor Heterojunctions for Efficient and Stable Solar Water Oxidation.

    Science.gov (United States)

    Chen, Le; Yang, Jinhui; Klaus, Shannon; Lee, Lyman J; Woods-Robinson, Rachel; Ma, Jie; Lum, Yanwei; Cooper, Jason K; Toma, Francesca M; Wang, Lin-Wang; Sharp, Ian D; Bell, Alexis T; Ager, Joel W

    2015-08-05

    Achieving stable operation of photoanodes used as components of solar water splitting devices is critical to realizing the promise of this renewable energy technology. It is shown that p-type transparent conducting oxides (p-TCOs) can function both as a selective hole contact and corrosion protection layer for photoanodes used in light-driven water oxidation. Using NiCo2O4 as the p-TCO and n-type Si as a prototypical light absorber, a rectifying heterojunction capable of light driven water oxidation was created. By placing the charge separating junction in the Si using a np(+) structure and by incorporating a highly active heterogeneous Ni-Fe oxygen evolution catalyst, efficient light-driven water oxidation can be achieved. In this structure, oxygen evolution under AM1.5G illumination occurs at 0.95 V vs RHE, and the current density at the reversible potential for water oxidation (1.23 V vs RHE) is >25 mA cm(-2). Stable operation was confirmed by observing a constant current density over 72 h and by sensitive measurements of corrosion products in the electrolyte. In situ Raman spectroscopy was employed to investigate structural transformation of NiCo2O4 during electrochemical oxidation. The interface between the light absorber and p-TCO is crucial to produce selective hole conduction to the surface under illumination. For example, annealing to produce more crystalline NiCo2O4 produces only small changes in its hole conductivity, while a thicker SiOx layer is formed at the n-Si/p-NiCo2O4 interface, greatly reducing the PEC performance. The generality of the p-TCO protection approach is demonstrated by multihour, stable, water oxidation with n-InP/p-NiCo2O4 heterojunction photoanodes.

  8. New materials for radiation hard semiconductor detectors

    CERN Document Server

    Sellin, P J; CERN. Geneva

    2006-01-01

    We present a review of the current status of research into new semiconductor materials for use as particle tracking detectors in very high radiation environments. This work is carried out within the framework of the CERN RD50 collaboration, which is investigating detector technologies suitable for operation at the proposed Super-LHC facility (SLHC). Tracking detectors operating at the SLHC in this environment will have to be capable of withstanding radiation levels arising from a luminosity of 1035 cm-2s-1 which will present severe challenges to current tracking detector technologies. The "new materials" activity within RD50 is investigating the performance of various semiconductor materials that potentially offer radiation hard alternatives to silicon devices. The main contenders in this study are silicon carbide, gallium nitride and amorphous silicon. In this paper we review the current status of these materials, in terms of material quality, commercial availability, charge transport properties, and radiati...

  9. Dopant type and/or concentration selective dry photochemical etching of semiconductor materials

    Energy Technology Data Exchange (ETDEWEB)

    Ashby, C.R.H.; Dishman, J.L.

    1985-10-11

    Disclosed is a method of selectively photochemically dry etching a first semiconductor material of a given composition in the presence of a second semiconductor material which is of a composition different from said first material, said second material substantially not being etched during said method. The method comprises subjecting both materials to the same photon flux of an energy greater than their respective direct bandgaps and to the same gaseous chemical etchant under conditions where said etchant would be ineffective for chemical etching of either material were the photons not present, said conditions also being such that the resultant electronic structure of the first semiconductor material under said photon flux is sufficient for the first material to undergo substantial photochemical etching under said conditions and being such that the resultant electronic structure of the second semiconductor material under said photon flux is not sufficient for the second material to undergo substantial photochemical etching under said conditions. In a preferred mode, the materials are subjected to a bias voltage which suppresses etching in n- or p-type material but not in p- or n-type material, respectively; or suppresses etching in the more heavily doped of two n-type or two p-type materials.

  10. Dopant type and/or concentration selective dry photochemical etching of semiconductor materials

    Energy Technology Data Exchange (ETDEWEB)

    Ashby, Carol I. H. (Edgewood, NM); Dishman, James L. (Albuquerque, NM)

    1987-01-01

    A method of selectively photochemically dry etching a first semiconductor material of a given composition in the presence of a second semiconductor material which is of a composition different from said first material, said second material substantially not being etched during said method, comprises subjecting both materials to the same photon flux of an energy greater than their respective direct bandgaps and to the same gaseous chemical etchant under conditions where said etchant would be ineffective for chemical etching of either material were the photons not present, said conditions also being such that the resultant electronic structure of the first semiconductor material under said photon flux is sufficient for the first material to undergo substantial photochemical etching under said conditions and being such that the resultant electronic structure of the second semiconductor material under said photon flux is not sufficient for the second material to undergo substantial photochemical etching under said conditions. In a preferred mode, the materials are subjected to a bias voltage which suppresses etching in n- or p- type material but not in p- or n-type material, respectively; or suppresses etching in the more heavily doped of two n-type or two p-type materials.

  11. Influence of chemically p-type doped active organic semiconductor on the film thickness versus performance trend in cyanine/C60 bilayer solar cells

    Science.gov (United States)

    Jenatsch, Sandra; Geiger, Thomas; Heier, Jakob; Kirsch, Christoph; Nüesch, Frank; Paracchino, Adriana; Rentsch, Daniel; Ruhstaller, Beat; C Véron, Anna; Hany, Roland

    2015-01-01

    Simple bilayer organic solar cells rely on very thin coated films that allow for effective light absorption and charge carrier transport away from the heterojunction at the same time. However, thin films are difficult to coat on rough substrates or over large areas, resulting in adverse shorting and low device fabrication yield. Chemical p-type doping of organic semiconductors can reduce Ohmic losses in thicker transport layers through increased conductivity. By using a Co(III) complex as chemical dopant, we studied doped cyanine dye/C60 bilayer solar cell performance for increasing dye film thickness. For films thicker than 50 nm, doping increased the power conversion efficiency by more than 30%. At the same time, the yield of working cells increased to 80%. We addressed the fate of the doped cyanine dye, and found no influence of doping on solar cell long term stability. PMID:27877804

  12. Influence of chemically p-type doped active organic semiconductor on the film thickness versus performance trend in cyanine/C60 bilayer solar cells.

    Science.gov (United States)

    Jenatsch, Sandra; Geiger, Thomas; Heier, Jakob; Kirsch, Christoph; Nüesch, Frank; Paracchino, Adriana; Rentsch, Daniel; Ruhstaller, Beat; C Véron, Anna; Hany, Roland

    2015-06-01

    Simple bilayer organic solar cells rely on very thin coated films that allow for effective light absorption and charge carrier transport away from the heterojunction at the same time. However, thin films are difficult to coat on rough substrates or over large areas, resulting in adverse shorting and low device fabrication yield. Chemical p-type doping of organic semiconductors can reduce Ohmic losses in thicker transport layers through increased conductivity. By using a Co(III) complex as chemical dopant, we studied doped cyanine dye/C60 bilayer solar cell performance for increasing dye film thickness. For films thicker than 50 nm, doping increased the power conversion efficiency by more than 30%. At the same time, the yield of working cells increased to 80%. We addressed the fate of the doped cyanine dye, and found no influence of doping on solar cell long term stability.

  13. Nanostructured Semiconductor Materials for Dye-Sensitized Solar Cells

    Directory of Open Access Journals (Sweden)

    Carmen Cavallo

    2017-01-01

    Full Text Available Since O’Regan and Grätzel’s first report in 1991, dye-sensitized solar cells (DSSCs appeared immediately as a promising low-cost photovoltaic technology. In fact, though being far less efficient than conventional silicon-based photovoltaics (being the maximum, lab scale prototype reported efficiency around 13%, the simple design of the device and the absence of the strict and expensive manufacturing processes needed for conventional photovoltaics make them attractive in small-power applications especially in low-light conditions, where they outperform their silicon counterparts. Nanomaterials are at the very heart of DSSC, as the success of its design is due to the use of nanostructures at both the anode and the cathode. In this review, we present the state of the art for both n-type and p-type semiconductors used in the photoelectrodes of DSSCs, showing the evolution of the materials during the 25 years of history of this kind of devices. In the case of p-type semiconductors, also some other energy conversion applications are touched upon.

  14. III-V semiconductor materials and devices

    CERN Document Server

    Malik, R J

    1989-01-01

    The main emphasis of this volume is on III-V semiconductor epitaxial and bulk crystal growth techniques. Chapters are also included on material characterization and ion implantation. In order to put these growth techniques into perspective a thorough review of the physics and technology of III-V devices is presented. This is the first book of its kind to discuss the theory of the various crystal growth techniques in relation to their advantages and limitations for use in III-V semiconductor devices.

  15. Fundamentals of semiconductors physics and materials properties

    CERN Document Server

    Yu, Peter Y

    1996-01-01

    Fundamentals of Semiconductors attempts to fill the gap between a general solid-state physics textbook and research articles by providing detailed explanations of the electronic, vibrational, transport, and optical properties of semiconductors The approach is physical and intuitive rather than formal and pedantic Theories are presented to explain experimental results This textbook has been written with both students and researchers in mind Its emphasis is on understanding the physical properties of Si and similar tetrahedrally coordinated semiconductors The explanations are based on physical insights Each chapter is enriched by an extensive collection of tables of material parameters, figures and problems Many of these problems 'lead the student by the hand' to arrive at the results

  16. Fundamentals of semiconductors physics and materials properties

    CERN Document Server

    Yu, Peter Y

    2010-01-01

    This fourth edition of the well-established Fundamentals of Semiconductors serves to fill the gap between a general solid-state physics textbook and research articles by providing detailed explanations of the electronic, vibrational, transport, and optical properties of semiconductors. The approach is physical and intuitive rather than formal and pedantic. Theories are presented to explain experimental results. This textbook has been written with both students and researchers in mind. Its emphasis is on understanding the physical properties of Si and similar tetrahedrally coordinated semiconductors. The explanations are based on physical insights. Each chapter is enriched by an extensive collection of tables of material parameters, figures, and problems. Many of these problems "lead the student by the hand" to arrive at the results. The major changes made in the fourth edition include: an extensive appendix about the important and by now well-established deep center known as the DX center, additional problems...

  17. Solar Superabsorption of Semiconductor Materials

    CERN Document Server

    Yu, Yiling; Cao, Linyou

    2013-01-01

    We theoretically demonstrate the fundamental limit in volume for given materials (e.g. Si, a-Si, CdTe) to fully absorb the solar radiation above bandgap, which we refer as solar superabsorption limit. We also point out the general principles for experimentally designing light trapping structures to approach the superabsorption. This study builds upon an intuitive model, coupled leaky mode theory (CLMT), for the analysis of light absorption in nanostructures. The CLMT provides a useful variable transformation. Unlike the existing methods that rely on information of physical features (e.g. morphology, dimensionality) to analyze light absorption, the CLMT can evaluate light absorption in given materials with only two variables, the radiative loss and the resonant wavelength, of leaky modes, regardless the physical features of the materials. This transformation allows for surveying the entire variable space to find out the solar superabsorption and provides physical insights to guide the design of solar superabso...

  18. Chemical Defects, Electronic Structure, and Transport in N-type and P-type Organic Semiconductors: First Principles Theory

    Science.gov (United States)

    2012-11-29

    boundaries. A paper describing the work was published in Nature Materials. {J. Rivnay, L.H. Jimison, J. E. Northrup, M. F. Toney, R. Noriega , S. Lu, T. J...Switzerland.[4] [1] J. Rivnay, R. Noriega , J. E. Northrup, R. J. Kline, M. F. Toney, and A. Salleo, Structural origin of gap states in semicrystalline...1] J. Rivnay, L.H. Jimison, J. E. Northrup, M. F. Toney, R. Noriega , S. Lu, T. J. Marks, A, Facchetti, and A. Salleo, Large modulation of

  19. Wide-gap layered oxychalcogenide semiconductors: materials, electronic structures and optoelectronic properties.

    OpenAIRE

    Ueda, Kazushige; Hiramatsu, Hidenori; Hirano, Masahiro; Kamiya, Toshio; Hosono, Hideo

    2006-01-01

    Applying the concept of materials design for transparent conductive oxides to layered oxychalcogenides, several p-type and n-type layered oxychalcogenides were proposed as wide-gap semiconductors and examined their basic optical and electrical properties. The layered oxychalcogenides are composed of ionic oxide layers and covalent chalcogenide layers, which bring wide-gap and conductive properties to these materials, respectively. The electronic structures of the materials were...

  20. Fundamental properties of semiconductor materials, and material performance in detectors

    Science.gov (United States)

    Casper, K. J.

    1973-01-01

    Procedures for determining fundamental properties of semiconductor materials, their performance as radiation detectors, and their service life as such detectors are given. Relationships were established between the minority carrier lifetime in the bulk of the material and the charge collection efficiency of the detector.

  1. New materials for radiation hard semiconductor dectectors

    Science.gov (United States)

    Sellin, P. J.; Vaitkus, J.

    2006-02-01

    We present a review of the current status of research into new semiconductor materials for use as particle tracking detectors in very high radiation environments. This work is carried out within the framework of the CERN RD50 collaboration, which is investigating detector technologies suitable for operation at the proposed super-LHC facility (SLHC). Tracking detectors operating at the SLHC in this environment will have to be capable of withstanding radiation levels arising from a luminosity of 10 35 cm -2 s -1 which will present severe challenges to current tracking detector technologies. The "new materials" activity within RD50 is investigating the performance of various semiconductor materials that potentially offer radiation hard alternatives to silicon devices. The main contenders in this study are silicon carbide, gallium nitride and amorphous silicon. In this paper we review the current status of these materials, in terms of material quality, commercial availability, charge transport properties, and radiation hardness studies. Whilst these materials currently show considerable promise for use as radiation hard tracking detectors, their ultimate success will depend on the continued improvement of the availability of high quality material.

  2. Thermoelectric properties of p-type Bi-Sb-Te compositionally graded thermoelectric materials with different barriers

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    In order to find more suitable materials as barriers and to improve the thermoelectric properties, p-type (BiSb)2Te3 (0.85, 0.9) two segments compositionally graded thermoelectric materials (CGTM) with different barriers were fabricated by conventional hot pressure method. Metals Fe, Co, Cu and Al were used as barriers between two segments. The effects of different barriers on thermoelectric properties of CGTM were investigated. The results show that metal Fe is more stable and suitable as the barrier.

  3. Liquid Crystalline Semiconductors Materials, properties and applications

    CERN Document Server

    Kelly, Stephen; O'Neill, Mary

    2013-01-01

    This is an exciting stage in the development of organic electronics. It is no longer an area of purely academic interest as increasingly real applications are being developed, some of which are beginning to come on-stream. Areas that have already been commercially developed or which are under intensive development include organic light emitting diodes (for flat panel displays and solid state lighting), organic photovoltaic cells, organic thin film transistors (for smart tags and flat panel displays) and sensors. Within the family of organic electronic materials, liquid crystals are relative newcomers. The first electronically conducting liquid crystals were reported in 1988 but already a substantial literature has developed. The advantage of liquid crystalline semiconductors is that they have the easy processability of amorphous and polymeric semiconductors but they usually have higher charge carrier mobilities. Their mobilities do not reach the levels seen in crystalline organics but they circumvent all of t...

  4. Advances in Rare Earth Application to Semiconductor Materials and Devices

    Institute of Scientific and Technical Information of China (English)

    屠海令

    2004-01-01

    The development of rare earths (RE) applications to semiconductor materials and devices is reviewed. The recent advances in RE doped silicon light emitting diodes (LED) and display materials are described. The various technologies of incorporating RE into semiconductor materials and devices are presented. The RE high dielectric materials, RE silicides and the phase transition of RE materials are also discussed. Finally, the paper describes the prospects of the RE application to semiconductor industry.

  5. Current transport mechanism at metal-semiconductor nanoscale interfaces based on ultrahigh density arrays of p-type NiO nano-pillars.

    Science.gov (United States)

    Nandy, Suman; Gonçalves, Gonçalo; Pinto, Joana Vaz; Busani, Tito; Figueiredo, Vitor; Pereira, Luís; Paiva Martins, Rodrigo Ferrão; Fortunato, Elvira

    2013-12-07

    The present work focuses on a qualitative analysis of localised I-V characteristics based on the nanostructure morphology of highly dense arrays of p-type NiO nano-pillars (NiO-NPs). Vertically aligned NiO-NPs have been grown on different substrates by using a glancing angle deposition (GLAD) technique. The preferred orientation of as grown NiO-NPs was controlled by the deposition pressure. The NiO-NPs displayed a polar surface with a microscopic dipole moment along the (111) plane (Tasker's type III). Consequently, the crystal plane dependent surface electron accumulation layer and the lattice disorder at the grain boundary interface showed a non-uniform current distribution throughout the sample surface, demonstrated by a conducting AFM technique (c-AFM). The variation in I-V for different points in a single current distribution grain (CD-grain) has been attributed to the variation of Schottky barrier height (SBH) at the metal-semiconductor (M-S) interface. Furthermore, we observed that the strain produced during the NiO-NPs growth can modulate the SBH. Inbound strain acts as an external field to influence the local electric field at the M-S interface causing a variation in SBH with the NPs orientation. This paper shows that vertical arrays of NiO-NPs are potential candidates for nanoscale devices because they have a great impact on the local current transport mechanism due to its nanostructure morphology.

  6. Impact of strain on gate-induced floating body effect for partially depleted silicon-on-insulator p-type metal–oxide–semiconductor-field-effect-transistors

    Energy Technology Data Exchange (ETDEWEB)

    Lo, Wen-Hung [Department of Physics, National Sun Yat-Sen University, Kaohsiung, Taiwan, ROC (China); Chang, Ting-Chang, E-mail: tcchang@mail.phys.nsysu.edu.tw [Department of Physics, National Sun Yat-Sen University, Kaohsiung, Taiwan, ROC (China); Center for Nanoscience and Nanotechnology, National Sun Yat-Sen University, Kaohsiung, Taiwan, ROC (China); Dai, Chih-Hao [Department of Photonics, National Sun Yat-Sen University, Kaohsiung, Taiwan, ROC (China); Chung, Wan-Lin [Department of Physics, National Sun Yat-Sen University, Kaohsiung, Taiwan, ROC (China); Chen, Ching-En; Ho, Szu-Han [Department of Electronics Engineering, National Chiao Tung University, Hsinchu, Taiwan, ROC (China); Tsai, Jyun-Yu [Department of Physics, National Sun Yat-Sen University, Kaohsiung, Taiwan, ROC (China); Chen, Hua-Mao [Department of Photonics and Institute of Electro-Optical Engineering, National Chiao Tung University, Hsinchu, Taiwan, ROC (China); Liu, Guan-Ru [Department of Physics, National Sun Yat-Sen University, Kaohsiung, Taiwan, ROC (China); Cheng, Osbert; Huang, Cheng-Tung [Device Department, United Microelectronics Corporation, Tainan Science Park, Taiwan, ROC (China)

    2013-01-01

    This work investigates impact of mechanical strain on gate-induced-floating-body-effect (GIFBE) for partially depleted silicon-on-insulator p-type metal–oxide–semiconductor field effect transistors (PD SOI p-MOSFETs). First part, the original mechanism of GIFBE on PD SOI p-MOSFETs is studied. The experimental results indicate that GIFBE causes a reduction in oxide electric field (E{sub ox}), resulting in an underestimate of negative-bias temperature instability (NBTI) degradation. This can be attributed to the electrons tunneling from the process-induced partial n{sup +} poly gate and anode electron injection (AEI) model, rather than the electron valence band tunneling (EVB) widely accepted as the mechanism for n-MOSFETs. And then, the second part shows that the strained FB device has less NBTI degradation than the unstrained devices. This behavior can be attributed to the fact that more electron accumulation was induced by strain-induced band gap narrowing, reducing NBTI significantly. - Highlights: ► This work investigates the impact of mechanical strain on GIFBE for PD SOI p-MOSFETs. ► FB device shows an insignificant NBTI due to GIFBE. ► GIFBE results from the partial n{sup +} poly gate and anode electron injection model. ► The strained FB device has less NBTI degradation than unstrained devices. ► We verify the band gap narrowing causes less NBTI on strained FB device.

  7. Impact of mechanical stress on gate tunneling currents of germanium and silicon p-type metal-oxide-semiconductor field-effect transistors and metal gate work function

    Science.gov (United States)

    Choi, Youn Sung; Numata, Toshinori; Nishida, Toshikazu; Harris, Rusty; Thompson, Scott E.

    2008-03-01

    Uniaxial four-point wafer bending stress-altered gate tunneling currents are measured for germanium (Ge)/silicon (Si) channel metal-oxide-semiconductor field-effect transistors (MOSFETs) with HfO2/SiO2 gate dielectrics and TiN/P+ poly Si electrodes. Carrier separation is used to measure electron and hole currents. The strain-altered hole tunneling current from the p-type inversion layer of Ge is measured to be ˜4 times larger than that for the Si channel MOSFET, since the larger strain-induced valence band-edge splitting in Ge results in more hole repopulation into a subband with a smaller out-of-plane effective mass and a lower tunneling barrier height. The strain-altered electron tunneling current from the metal gate is measured and shown to change due to strain altering the metal work function as quantified by flatband voltage shift measurements of Si MOS capacitors with TaN electrodes.

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

    Science.gov (United States)

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

    2014-11-25

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

  9. Space Research Results Purify Semiconductor Materials

    Science.gov (United States)

    2010-01-01

    While President Obama's news that NASA would encourage private companies to develop vehicles to take NASA into space may have come as a surprise to some, NASA has always encouraged private companies to invest in space. More than two decades ago, NASA established Commercial Space Centers across the United States to encourage industry to use space as a place to conduct research and to apply NASA technology to Earth applications. Although the centers are no longer funded by NASA, the advances enabled by that previous funding are still impacting us all today. For example, the Space Vacuum Epitaxy Center (SVEC) at the University of Houston, one of the 17 Commercial Space Centers, had a mission to create advanced thin film semiconductor materials and devices through the use of vacuum growth technologies both on Earth and in space. Making thin film materials in a vacuum (low-pressure environment) is advantageous over making them in normal atmospheric pressures, because contamination floating in the air is lessened in a vacuum. To grow semiconductor crystals, researchers at SVEC utilized epitaxy the process of depositing a thin layer of material on top of another thin layer of material. On Earth, this process took place in a vacuum chamber in a clean room lab. For space, the researchers developed something called the Wake Shield Facility (WSF), a 12-foot-diameter disk-shaped platform designed to grow thin film materials using the low-pressure environment in the wake of the space shuttle. Behind an orbiting space shuttle, the vacuum levels are thousands of times better than in the best vacuum chambers on Earth. Throughout the 1990s, the WSF flew on three space shuttle missions as a series of proof-of-concept missions. These experiments are a lasting testament to the success of the shuttle program and resulted in the development of the first thin film materials made in the vacuum of space, helping to pave the way for better thin film development on Earth.

  10. Electrochemical Characterization of Semiconductor Materials and Structures

    Science.gov (United States)

    1997-01-01

    For a period covering October 1, 1995 through August 12, 1996, the research group at CSU has conducted theoretical and experimental research on "Electrochemical Characterization of Semiconductor Materials and Structures. " The objective of this investigation was to demonstrate the applicability of electrochemical techniques for characterization of complex device structures based on InP and GaAs, Ge, InGaAs, InSb, InAs and InSb, including: (1) accurate EC-V net majority carrier concentration depth profiling, and (2) surface and bulk structural and electrical type defect densities. Our motivation for this R&D effort was as follows: "Advanced space solar cells and ThermoPhotoVoltaic (TPV) cells are fabricated using a large variety of III-V materials based on InP and GaAs for solar cells and low bandgap materials such as Ge, InGaAs, InAs and InSb for TPV applications. At the present time for complex device structures using these materials, however, there is no simple way to assess the quality of these structures prior to device fabrication. Therefore, process optimization is a very time consuming and a costly endeavor". Completion of this R&D effort would have had unquestionable benefits for space solar cell and TPV cells, since electrochemical characterization of the above cell structures, if properly designed can provide many useful structural and electrical material information virtually at any depth inside various layers and at the interfaces. This, could have been applied for step-by-step process optimization, which could have been used for fabrication of new generation high efficiency, low cost space PV and TPV cells.

  11. Chalcogenoarene Semiconductors: New Ideas From Old Materials

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Lei; Fakhouri, Sami M.; Liu, Feng; Timmons, Justin C.; Ran, Niva A.; Briseno, Alejandro L.

    2010-01-01

    There are certain aspects of the electronic and packing behavior of planar aromatic molecules containing exocyclic chalcogen atoms (i.e., sulfur, selenium, tellurium) which need considerable re-enlightenment. This class of semiconductors was once regarded as next-generation π-donors for applications in charge-transfer complexes. With the advent of new device technologies such as light-emitting diodes, solar cells, and organic transistors, the interest in charge-transfer complexes eventually tapered off. However, significant progress in the use of this class of materials in modern organic devices has been reported over the last five years. In this article, we review the exocyclic arenes with chalcogen atoms in peri-positions, summarize synthetic routes to these compounds and take a close look at their basic properties. Particular emphasis is placed upon their packing arrangements and the effect of exocyclic chalcogen atoms on the crystal packing motifs. Selected example applications from this class of materials in different fields will be highlighted. As a final note, we provide a prediction for their use in mainstream applications such as energy and fundamental charge transport/generation.

  12. Composition/bandgap selective dry photochemical etching of semiconductor materials

    Energy Technology Data Exchange (ETDEWEB)

    Ashby, C.I.H.; Dishman, J.L.

    1985-10-11

    Disclosed is a method of selectively photochemically dry etching a first semiconductor material of a given composition and direct bandgap Eg/sub 1/ in the presence of a second semiconductor material of a different composition and direct bandgap Eg/sub 2/, wherein Eg/sub 2/ > Eg/sub 1/, said second semiconductor material substantially not being etched during said method. The method comprises subjecting both materials to the same photon flux and to the same gaseous etchant under conditions where said etchant would be ineffective for chemical etching of either material were the photons not present, said photons being of an energy greater than Eg/sub 1/ but less than Eg/sub 2/, whereby said first semiconductor material is photochemically etched and said second material is substantially not etched.

  13. Composition/bandgap selective dry photochemical etching of semiconductor materials

    Energy Technology Data Exchange (ETDEWEB)

    Ashby, Carol I. H. (Edgewood, NM); Dishman, James L. (Albuquerque, NM)

    1987-01-01

    A method of selectively photochemically dry etching a first semiconductor material of a given composition and direct bandgap Eg.sub.1 in the presence of a second semiconductor material of a different composition and direct bandgap Eg.sub.2, wherein Eg.sub.2 >Eg.sub.1, said second semiconductor material substantially not being etched during said method, comprises subjecting both materials to the same photon flux and to the same gaseous etchant under conditions where said etchant would be ineffective for chemical etching of either material were the photons not present, said photons being of an energy greater than Eg.sub.1 but less than Eg.sub.2, whereby said first semiconductor material is photochemically etched and said second material is substantially not etched.

  14. Composition/bandgap selective dry photochemical etching of semiconductor materials

    Energy Technology Data Exchange (ETDEWEB)

    Ashby, C.I.H.; Dishman, J.L.

    1987-03-10

    A method is described of selectively photochemically dry etching a first semiconductor material of a given composition and direct bandgap E/sub g1/ in the presence of a second semiconductor material of a different composition and direct bandgap E/sub g2/, wherein E/sub g2/>E/sub g1/. The second semiconductor material is not substantially etched during the method, comprising subjecting both materials to the same photon flux and to the same gaseous etchant under conditions where the etchant would be ineffective for chemical etching of either material where the photons are not present, the photons being of an energy greater than E/sub g1/ but less than E/sub g2/, whereby the first semiconductor material is photochemically etched and the second material is substantially not etched.

  15. Optical correlators with fast updating speed using photorefractive semiconductor materials

    Science.gov (United States)

    Gheen, Gregory; Cheng, Li-Jen

    1988-01-01

    The performance of an updatable optical correlator which uses a photorefractive semiconductor to generate real-time matched filters is discussed. The application of compound semiconductors makes possible high-speed operation and low optical input intensities. The Bragg diffraction is considered, along with the speed and power characteristics of these materials. Experimental results on photorefractive GaAs are presented.

  16. Semiconductor Metal-Organic Frameworks: Future Low-Bandgap Materials.

    Science.gov (United States)

    Usman, Muhammad; Mendiratta, Shruti; Lu, Kuang-Lieh

    2017-02-01

    Metal-organic frameworks (MOFs) with low density, high porosity, and easy tunability of functionality and structural properties, represent potential candidates for use as semiconductor materials. The rapid development of the semiconductor industry and the continuous miniaturization of feature sizes of integrated circuits toward the nanometer (nm) scale require novel semiconductor materials instead of traditional materials like silicon, germanium, and gallium arsenide etc. MOFs with advantageous properties of both the inorganic and the organic components promise to serve as the next generation of semiconductor materials for the microelectronics industry with the potential to be extremely stable, cheap, and mechanically flexible. Here, a perspective of recent research is provided, regarding the semiconducting properties of MOFs, bandgap studies, and their potential in microelectronic devices. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Engineering the cell-semiconductor interface: a materials modification approach using II-VI and III-V semiconductor materials.

    Science.gov (United States)

    Bain, Lauren E; Ivanisevic, Albena

    2015-02-18

    Developing functional biomedical devices based on semiconductor materials requires an understanding of interactions taking place at the material-biosystem interface. Cell behavior is dependent on the local physicochemical environment. While standard routes of material preparation involve chemical functionalization of the active surface, this review emphasizes both biocompatibility of unmodified surfaces as well as use of topographic features in manipulating cell-material interactions. Initially, the review discusses experiments involving unmodified II-VI and III-V semiconductors - a starting point for assessing cytotoxicity and biocompatibility - followed by specific surface modification, including the generation of submicron roughness or the potential effect of quantum dot structures. Finally, the discussion turns to more recent work in coupling topography and specific chemistry, enhancing the tunability of the cell-semiconductor interface. With this broadened materials approach, researchers' ability to tune the interactions between semiconductors and biological environments continues to improve, reaching new heights in device function.

  18. Fe-Cr-Al containing oxide semiconductors as potential solar water-splitting materials.

    Science.gov (United States)

    Sliozberg, Kirill; Stein, Helge S; Khare, Chinmay; Parkinson, Bruce A; Ludwig, Alfred; Schuhmann, Wolfgang

    2015-03-01

    A high-throughput thin film materials library for Fe-Cr-Al-O was obtained by reactive magnetron cosputtering and analyzed with automated EDX and XRD to elucidate compositional and structural properties. An automated optical scanning droplet cell was then used to perform photoelectrochemical measurements of 289 compositions on the library, including electrochemical stability, potentiodynamic photocurrents and photocurrent spectroscopy. The photocurrent onset and open circuit potentials of two semiconductor compositions (n-type semiconducting: Fe51Cr47Al2Ox, p-type semiconducting Fe36.5Cr55.5Al8Ox) are favorable for water splitting. Cathodic photocurrents are observed at 1.0 V vs RHE for the p-type material exhibiting an open circuit potential of 0.85 V vs RHE. The n-type material shows an onset of photocurrents at 0.75 V and an open circuit potential of 0.6 V. The p-type material showed a bandgap of 1.55 eV, while the n-type material showed a bandgap of 1.97 eV.

  19. Semiconductor Material and Device Characterization, 3rd Edition

    Science.gov (United States)

    Schroder, Dieter K.

    2005-12-01

    Semiconductor Material and Device Characterizationis the only book on the market devoted to the characterization techniques used by the modern semiconductor industry to measure diverse semiconductor materials and devices. It covers the full range of electrical and optical characterization methods while thoroughly treating the more specialized chemical and physical techniques. In the third edition, Professor Schroder has rewritten parts of each chapter and added two new chapters (Charge Based Measurements and Failure Analysis and Reliability), redrawn and updated most figures, and included new problems and approximately 100 new references. * New end of chapter problems * Outdated figures have been redone and replaced with current data * Up-to-date bibliography with over 1400 references * Professor Schroder is recognized as the authority in the field of semiconductor characterization

  20. Synthesis and characterization of a new organic semiconductor material

    Energy Technology Data Exchange (ETDEWEB)

    Tiffour, Imane [Laboratoire de Génie Physique, Département de Physique, Université de Tiaret, Tiaret 14000 (Algeria); Faculté des Sciences et Technologies, Université Mustapha Stambouli, Mascara 29000 (Algeria); Dehbi, Abdelkader [Laboratoire de Génie Physique, Département de Physique, Université de Tiaret, Tiaret 14000 (Algeria); Mourad, Abdel-Hamid I., E-mail: ahmourad@uaeu.ac.ae [Mechanical Engineering Department, Faculty of Engineering, United Arab Emirates University, Al-Ain, P.O. Box 15551 (United Arab Emirates); Belfedal, Abdelkader [Faculté des Sciences et Technologies, Université Mustapha Stambouli, Mascara 29000 (Algeria); LPCMME, Département de Physique, Université d' Oran Es-sénia, 3100 Oran (Algeria)

    2016-08-01

    The objective of this study is to create an ideal mixture of Acetaminophen/Curcumin leading to a new and improved semiconductor material, by a study of the electrical, thermal and optical properties. This new material will be compared with existing semiconductor technology to discuss its viability within the industry. The electrical properties were investigated using complex impedance spectroscopy and optical properties were studied by means of UV-Vis spectrophotometry. The electric conductivity σ, the dielectric constant ε{sub r}, the activation energy E{sub a}, the optical transmittance T and the gap energy E{sub g} have been investigated in order to characterize our organic material. The electrical conductivity of the material is approximately 10{sup −5} S/m at room temperature, increasing the temperature causes σ to increase exponentially to approximately 10{sup −4} S/m. The activation energy obtained for the material is equal to 0.49 ± 0.02 ev. The optical absorption spectra show that the investigating material has absorbance in the visible range with a maximum wavelength (λ{sub max}) 424 nm. From analysis, the absorption spectra it was found the optical band gap equal to 2.6 ± 0.02 eV and 2.46 ± 0.02 eV for the direct and indirect transition, respectively. In general, the study shows that the developed material has characteristics of organic semiconductor material that has a promising future in the field of organic electronics and their potential applications, e.g., photovoltaic cells. - Highlights: • Development of a new organic acetaminophen/Curcumin semiconductor material. • The developed material has characteristics of an organic semiconductor. • It has electrical conductivity comparable to available organic semiconductors. • It has high optical transmittance and low permittivity/dielectric constant.

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

    Energy Technology Data Exchange (ETDEWEB)

    Dib, E., E-mail: elias.dib@for.unipi.it [Dipartimento di Ingegneria dell' Informazione, Università di Pisa, 56122 Pisa (Italy); Carrillo-Nuñez, H. [Integrated Systems Laboratory ETH Zürich, Gloriastrasse 35, 8092 Zürich (Switzerland); Cavassilas, N.; Bescond, M. [IM2NP, UMR CNRS 6242, Bât. IRPHE, Technopôle de Château-Gombert, 13384 Marseille Cedex 13 (France)

    2016-01-28

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

  2. Compound Semiconductor Materials, Devices and Circuits

    Science.gov (United States)

    1988-06-01

    Semiconductors", L.A. Coldren, J.G. Mendoza - Alvarez and R.H. Yan, Aopl. Phys. Lett., 51, 792-794 (1987). JSEP PUBLICATIONS AND PRESENTATIONS 1. "Room...self-consistent Monte Carlo transport formulation and its applicat... to small graded heterostructure devices; (e) optical modulation based on the...L.F. Eastman 1 0 TASK 3 FUNDAMENTAL PHENOMENON IN ULTRASHORT DEVICES E.D. Wolf, L.F. Eastman and P.J. Tasker 1 9 TASK 4 ENSEMBLE MONTE CARLO

  3. Optimization of p-type Segmented Bi2Te3/CoSb3 Thermoelectric Material Prepared by Spark Plasma Sintering

    Institute of Scientific and Technical Information of China (English)

    WANG Jun; TANG Xinfeng; LIU Haiqiang; YANG Xiuli; ZHANG Qingjie

    2006-01-01

    A kind of p- type segmented Bi2 Te3/ CoSb3 thermoelectric material was prepared by spark plasma sintering( SPS ). When the segmented materials were used at the temperature ranging from 300 K to 800 K, the junction temperature was optimized, which is about 500 K, and the corresponding length ratio of CoSb3 to Bi2 Te3 is about 15:2. The measured maximum power output of segmented materials is about 320 W·m-2, which is about 1.8 times as high as that of monolithic material CoSb3 under the same measuring conditions.

  4. Conduit for high temperature transfer of molten semiconductor crystalline material

    Science.gov (United States)

    Fiegl, George (Inventor); Torbet, Walter (Inventor)

    1983-01-01

    A conduit for high temperature transfer of molten semiconductor crystalline material consists of a composite structure incorporating a quartz transfer tube as the innermost member, with an outer thermally insulating layer designed to serve the dual purposes of minimizing heat losses from the quartz tube and maintaining mechanical strength and rigidity of the conduit at the elevated temperatures encountered. The composite structure ensures that the molten semiconductor material only comes in contact with a material (quartz) with which it is compatible, while the outer layer structure reinforces the quartz tube, which becomes somewhat soft at molten semiconductor temperatures. To further aid in preventing cooling of the molten semiconductor, a distributed, electric resistance heater is in contact with the surface of the quartz tube over most of its length. The quartz tube has short end portions which extend through the surface of the semiconductor melt and which are lef bare of the thermal insulation. The heater is designed to provide an increased heat input per unit area in the region adjacent these end portions.

  5. Tuning Bandgap of p-Type Cu2Zn(Sn, Ge)(S, Se)4 Semiconductor Thin Films via Aqueous Polymer-Assisted Deposition.

    Science.gov (United States)

    Yi, Qinghua; Wu, Jiang; Zhao, Jie; Wang, Hao; Hu, Jiapeng; Dai, Xiao; Zou, Guifu

    2017-01-18

    Bandgap engineering of kesterite Cu2Zn(Sn, Ge)(S, Se)4 with well-controlled stoichiometric composition plays a critical role in sustainable inorganic photovoltaics. Herein, a cost-effective and reproducible aqueous solution-based polymer-assisted deposition approach is developed to grow p-type Cu2Zn(Sn, Ge)(S, Se)4 thin films with tunable bandgap. The bandgap of Cu2Zn(Sn, Ge)(S, Se)4 thin films can be tuned within the range 1.05-1.95 eV using the aqueous polymer-assisted deposition by accurately controlling the elemental compositions. One of the as-grown Cu2Zn(Sn, Ge)(S, Se)4 thin films exhibits a hall coefficient of +137 cm(3)/C. The resistivity, concentration and carrier mobility of the Cu2ZnSn(S, Se)4 thin film are 3.17 ohm·cm, 4.5 × 10(16) cm(-3), and 43 cm(2)/(V·S) at room temperature, respectively. Moreover, the Cu2ZnSn(S, Se)4 thin film when used as an active layer in a solar cell leads to a power conversion efficiency of 3.55%. The facile growth of Cu2Zn(Sn, Ge)(S, Se)4 thin films in an aqueous system, instead of organic solvents, provides great promise as an environmental-friendly platform to fabricate a variety of single/multi metal chalcogenides for the thin film industry and solution-processed photovoltaic devices.

  6. Photoconductive terahertz generation from textured semiconductor materials.

    Science.gov (United States)

    Collier, Christopher M; Stirling, Trevor J; Hristovski, Ilija R; Krupa, Jeffrey D A; Holzman, Jonathan F

    2016-01-01

    Photoconductive (PC) terahertz (THz) emitters are often limited by ohmic loss and Joule heating-as these effects can lead to thermal runaway and premature device breakdown. To address this, the proposed work introduces PC THz emitters based on textured InP materials. The enhanced surface recombination and decreased charge-carrier lifetimes of the textured InP materials reduce residual photocurrents, following the picosecond THz waveform generation, and this diminishes Joule heating in the emitters. A non-textured InP material is used as a baseline for studies of fine- and coarse-textured InP materials. Ultrafast pump-probe and THz setups are used to measure the charge-carrier lifetimes and THz response/photocurrent consumption of the respective materials and emitters. It is found that similar temporal and spectral characteristics can be achieved with the THz emitters, but the level of photocurrent consumption (yielding Joule heating) is greatly reduced in the textured materials.

  7. Growth of crystalline semiconductor materials on crystal surfaces

    CERN Document Server

    Aleksandrov, L

    2013-01-01

    Written for physicists, chemists, and engineers specialising in crystal and film growth, semiconductor electronics, and various applications of thin films, this book reviews promising scientific and engineering trends in thin films and thin-films materials science. The first part discusses the physical characteristics of the processes occurring during the deposition and growth of films, the principal methods of obtaining semiconductor films and of reparing substrate surfaces on which crystalline films are grown, and the main applications of films. The second part contains data on epitaxial i

  8. Wafer Fusion for Integration of Semiconductor Materials and Devices

    Energy Technology Data Exchange (ETDEWEB)

    Choquette, K.D.; Geib, K.M.; Hou, H.Q.; Allerman, A.A.; Kravitz, S.; Follstaedt, D.M.; Hindi, J.J.

    1999-05-01

    We have developed a wafer fusion technology to achieve integration of semiconductor materials and heterostructures with widely disparate lattice parameters, electronic properties, and/or optical properties for novel devices not now possible on any one substrate. Using our simple fusion process which uses low temperature (400-600 C) anneals in inert N{sub 2} gas, we have extended the scope of this technology to examine hybrid integration of dissimilar device technologies. As a specific example, we demonstrate wafer bonding vertical cavity surface emitting lasers (VCSELs) to transparent AlGaAs and GaP substrates to fabricate bottom-emitting short wavelength VCSELs. As a baseline fabrication technology applicable to many semiconductor systems, wafer fusion will revolutionize the way we think about possible semiconductor devices, and enable novel device configurations not possible by epitaxial growth.

  9. New semiconductor materials for magnetoelectronics at room temperature

    Indian Academy of Sciences (India)

    S K Kamilla; S Basu

    2002-11-01

    Most of the semiconductor materials are diamagnetic by nature and therefore cannot take active part in the operation of the magneto electronic devices. In order to enable them to be useful for such devices a recent effort has been made to develop diluted magnetic semiconductors (DMS) in which small quantity of magnetic ion is introduced into normal semiconductors. The first known such DMS are II–VI and III–V semiconductors diluted with magnetic ions like Mn, Fe, Co, Ni, etc. Most of these DMS exhibit very high electron and hole mobility and thus useful for high speed electronic devices. The recent DMS materials reported are (CdMn)Te, (GaMn)As, (GaMn)Sb, ZnMn(or Co)O, TiMn(or Co)O etc. They have been produced as thin films by MBE and other methods. This paper will discuss the details of the growth and properties of the DMS materials and some of their applications.

  10. Ferroelectric Rashba semiconductors as a novel class of multifunctional materials

    OpenAIRE

    Picozzi, Silvia

    2014-01-01

    The discovery of novel properties, effects or microscopic mechanisms in modern materials science is often driven by the quest for combining, into a single compound, several functionalities: not only the juxtaposition of the latter functionalities, but especially their coupling, can open new horizons in basic condensed matter physics, in materials science and technology. Semiconductor spintronics makes no exception. In this context, we have discovered by means of density-functional simulations...

  11. Anisotropy-based crystalline oxide-on-semiconductor material

    Science.gov (United States)

    McKee, Rodney Allen; Walker, Frederick Joseph

    2000-01-01

    A semiconductor structure and device for use in a semiconductor application utilizes a substrate of semiconductor-based material, such as silicon, and a thin film of a crystalline oxide whose unit cells are capable of exhibiting anisotropic behavior overlying the substrate surface. Within the structure, the unit cells of the crystalline oxide are exposed to an in-plane stain which influences the geometric shape of the unit cells and thereby arranges a directional-dependent quality of the unit cells in a predisposed orientation relative to the substrate. This predisposition of the directional-dependent quality of the unit cells enables the device to take beneficial advantage of characteristics of the structure during operation. For example, in the instance in which the crystalline oxide of the structure is a perovskite, a spinel or an oxide of similarly-related cubic structure, the structure can, within an appropriate semiconductor device, exhibit ferroelectric, piezoelectric, pyroelectric, electro-optic, ferromagnetic, antiferromagnetic, magneto-optic or large dielectric properties that synergistically couple to the underlying semiconductor substrate.

  12. Selective Conversion from p-Type to n-Type of Printed Bottom-Gate Carbon Nanotube Thin-Film Transistors and Application in Complementary Metal-Oxide-Semiconductor Inverters.

    Science.gov (United States)

    Xu, Qiqi; Zhao, Jianwen; Pecunia, Vincenzo; Xu, Wenya; Zhou, Chunshan; Dou, Junyan; Gu, Weibing; Lin, Jian; Mo, Lixin; Zhao, Yanfei; Cui, Zheng

    2017-03-30

    The fabrication of printed high-performance and environmentally stable n-type single-walled carbon nanotube (SWCNT) transistors and their integration into complementary (i.e., complementary metal-oxide-semiconductor, CMOS) circuits are widely recognized as key to achieving the full potential of carbon nanotube electronics. Here, we report a simple, efficient, and robust method to convert the polarity of SWCNT thin-film transistors (TFTs) using cheap and readily available ethanolamine as an electron doping agent. Printed p-type bottom-gate SWCNT TFTs can be selectively converted into n-type by deposition of ethanolamine inks on the transistor active region via aerosol jet printing. Resulted n-type TFTs show excellent electrical properties with an on/off ratio of 10(6), effective mobility up to 30 cm(2) V(-1) s(-1), small hysteresis, and small subthreshold swing (90-140 mV dec(-1)), which are superior compared to the original p-type SWCNT devices. The n-type SWCNT TFTs also show good stability in air, and any deterioration of performance due to shelf storage can be fully recovered by a short low-temperature annealing. The easy polarity conversion process allows construction of CMOS circuitry. As an example, CMOS inverters were fabricated using printed p-type and n-type TFTs and exhibited a large noise margin (50 and 103% of 1/2 Vdd = 1 V) and a voltage gain as high as 30 (at Vdd = 1 V). Additionally, the CMOS inverters show full rail-to-rail output voltage swing and low power dissipation (0.1 μW at Vdd = 1 V). The new method paves the way to construct fully functional complex CMOS circuitry by printed TFTs.

  13. Estimating Seebeck Coefficient of a p-Type High Temperature Thermoelectric Material Using Bee Algorithm Multi-layer Perception

    Science.gov (United States)

    Uysal, Fatih; Kilinc, Enes; Kurt, Huseyin; Celik, Erdal; Dugenci, Muharrem; Sagiroglu, Selami

    2017-08-01

    Thermoelectric generators (TEGs) convert heat into electrical energy. These energy-conversion systems do not involve any moving parts and are made of thermoelectric (TE) elements connected electrically in a series and thermally in parallel; however, they are currently not suitable for use in regular operations due to their low efficiency levels. In order to produce high-efficiency TEGs, there is a need for highly heat-resistant thermoelectric materials (TEMs) with an improved figure of merit ( ZT). Production and test methods used for TEMs today are highly expensive. This study attempts to estimate the Seebeck coefficient of TEMs by using the values of existing materials in the literature. The estimation is made within an artificial neural network (ANN) based on the amount of doping and production methods. Results of the estimations show that the Seebeck coefficient can approximate the real values with an average accuracy of 94.4%. In addition, ANN has detected that any change in production methods is followed by a change in the Seebeck coefficient.

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

    Science.gov (United States)

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

    2016-01-01

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

  15. Quantum materials. Lateral semiconductor nanostructures, hybrid systems and nanocrystals

    Energy Technology Data Exchange (ETDEWEB)

    Heitmann, Detlef (ed.) [Hamburg Univ. (Germany). Inst. fuer Angewandte Physik

    2010-07-01

    Semiconductor nanostructures are ideal systems to tailor the physical properties via quantum effects, utilizing special growth techniques, self-assembling, wet chemical processes or lithographic tools in combination with tuneable external electric and magnetic fields. Such systems are called ''Quantum Materials''.The electronic, photonic, and phononic properties of these systems are governed by size quantization and discrete energy levels. The charging is controlled by the Coulomb blockade. The spin can be manipulated by the geometrical structure, external gates and by integrating hybrid ferromagnetic emitters.This book reviews sophisticated preparation methods for quantum materials based on III-V and II-VI semiconductors and a wide variety of experimental techniques for the investigation of these interesting systems. It highlights selected experiments and theoretical concepts and gives such a state-of-the-art overview about the wide field of physics and chemistry that can be studied in these systems. (orig.)

  16. Materials and Reliability Handbook for Semiconductor Optical and Electron Devices

    CERN Document Server

    Pearton, Stephen

    2013-01-01

    Materials and Reliability Handbook for Semiconductor Optical and Electron Devices provides comprehensive coverage of reliability procedures and approaches for electron and photonic devices. These include lasers and high speed electronics used in cell phones, satellites, data transmission systems and displays. Lifetime predictions for compound semiconductor devices are notoriously inaccurate due to the absence of standard protocols. Manufacturers have relied on extrapolation back to room temperature of accelerated testing at elevated temperature. This technique fails for scaled, high current density devices. Device failure is driven by electric field or current mechanisms or low activation energy processes that are masked by other mechanisms at high temperature. The Handbook addresses reliability engineering for III-V devices, including materials and electrical characterization, reliability testing, and electronic characterization. These are used to develop new simulation technologies for device operation and ...

  17. n-Channel semiconductor materials design for organic complementary circuits.

    Science.gov (United States)

    Usta, Hakan; Facchetti, Antonio; Marks, Tobin J

    2011-07-19

    Organic semiconductors have unique properties compared to traditional inorganic materials such as amorphous or crystalline silicon. Some important advantages include their adaptability to low-temperature processing on flexible substrates, low cost, amenability to high-speed fabrication, and tunable electronic properties. These features are essential for a variety of next-generation electronic products, including low-power flexible displays, inexpensive radio frequency identification (RFID) tags, and printable sensors, among many other applications. Accordingly, the preparation of new materials based on π-conjugated organic molecules or polymers has been a central scientific and technological research focus over the past decade. Currently, p-channel (hole-transporting) materials are the leading class of organic semiconductors. In contrast, high-performance n-channel (electron-transporting) semiconductors are relatively rare, but they are of great significance for the development of plastic electronic devices such as organic field-effect transistors (OFETs). In this Account, we highlight the advances our team has made toward realizing moderately and highly electron-deficient n-channel oligomers and polymers based on oligothiophene, arylenediimide, and (bis)indenofluorene skeletons. We have synthesized and characterized a "library" of structurally related semiconductors, and we have investigated detailed structure-property relationships through optical, electrochemical, thermal, microstructural (both single-crystal and thin-film), and electrical measurements. Our results reveal highly informative correlations between structural parameters at various length scales and charge transport properties. We first discuss oligothiophenes functionalized with perfluoroalkyl and perfluoroarene substituents, which represent the initial examples of high-performance n-channel semiconductors developed in this project. The OFET characteristics of these compounds are presented with an

  18. Chalcopyrite semimagnetic semiconductors: From nanocomposite to homogeneous material

    Directory of Open Access Journals (Sweden)

    Kilanski L.

    2014-01-01

    Full Text Available Currently, complex ferromagnetic semiconductor systems are of significant interest due to their potential applicability in spintronics. A key feature in order to use semiconductor materials in spintronics is the presence of room temperature ferromagnetism. This feature was recently observed and is intensively studied in several Mn-alloyed II-IV-V2 group diluted magnetic semiconductor systems. The paper reviews the origin of room temperature ferromagnetism in II-IV-V2 compounds. In view of our recent reports the room temperature ferromagnetism in Mn-alloyed chalcopyrite semiconductors with more than 5 molar % of Mn is due to the presence of MnAs clusters. The solubility of magnetic impurities in bulk II-IV-V2 materials is of the order of a few percent, depending on the alloy composition. High values of the conducting hole - Mn ion exchange constant Jpd have significant value equal to 0.75 eV for Zn0.997Mn0.003GeAs2. The sample quality has significant effect on the magnetotransport of the alloy. The magnetoresistance of the alloy change main physical mechanism from spin-disorder scattering and weak localization for homogeneous samples to cluster-related geometrical effect observed for nanocomposite samples. The magnetoresistance of the II-IV-V2 alloys can be then tuned up to a few hundreds of percent via changes of the chemical composition of the alloy as well as a degree of disorder present in a material. [Projekat Ministarstva nauke Republike Srbije, br. III45003

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

    Science.gov (United States)

    Banerjee, Arghya; Chattopadhyay, Kalyan K

    2008-01-01

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

  20. New Organic Semiconductor Materials Applied in Organic Photovoltaic and Optical Devices

    National Research Council Canada - National Science Library

    Andre F. S. Guedes; Vilmar P. Guedes; Simone Tartari; Mônica L. Souza; Idaulo J. Cunha

    2015-01-01

    The development of flexible organic photovoltaic solar cells, using an optically transparent substrate material and organic semiconductor materials, has been widely utilized by the electronic industry...

  1. Neutron detection using boron gallium nitride semiconductor material

    Energy Technology Data Exchange (ETDEWEB)

    Atsumi, Katsuhiro [Department of Electrical and Electronic Engineering, Graduate School of Engineering, Shizuoka University, 3-5-1 Johoku, Naka-ku, Hamamatsu 432-8561 (Japan); Inoue, Yoku; Nakano, Takayuki, E-mail: ttnakan@ipc.shizuoka.ac.jp [Department of Electrical and Materials Science, Graduate School of Engineering, Shizuoka University, 3-5-1 Johoku, Naka-ku, Hamamatsu 432-8561 (Japan); Mimura, Hidenori; Aoki, Toru [Research Institute of Electronics, Shizuoka University, 3-5-1 Johoku, Naka-ku, Hamamatsu 432-8011 (Japan)

    2014-03-01

    In this study, we developed a new neutron-detection device using a boron gallium nitride (BGaN) semiconductor in which the B atom acts as a neutron converter. BGaN and gallium nitride (GaN) samples were grown by metal organic vapor phase epitaxy, and their radiation detection properties were evaluated. GaN exhibited good sensitivity to α-rays but poor sensitivity to γ-rays. Moreover, we confirmed that electrons were generated in the depletion layer under neutron irradiation. This resulted in a neutron-detection signal after α-rays were generated by the capture of neutrons by the B atoms. These results prove that BGaN is useful as a neutron-detecting semiconductor material.

  2. Neutron detection using boron gallium nitride semiconductor material

    Directory of Open Access Journals (Sweden)

    Katsuhiro Atsumi

    2014-03-01

    Full Text Available In this study, we developed a new neutron-detection device using a boron gallium nitride (BGaN semiconductor in which the B atom acts as a neutron converter. BGaN and gallium nitride (GaN samples were grown by metal organic vapor phase epitaxy, and their radiation detection properties were evaluated. GaN exhibited good sensitivity to α-rays but poor sensitivity to γ-rays. Moreover, we confirmed that electrons were generated in the depletion layer under neutron irradiation. This resulted in a neutron-detection signal after α-rays were generated by the capture of neutrons by the B atoms. These results prove that BGaN is useful as a neutron-detecting semiconductor material.

  3. Tris(2-(1H-pyrazol-1-yl)pyridine)cobalt(III) as p-type dopant for organic semiconductors and its application in highly efficient solid-state dye-sensitized solar cells.

    Science.gov (United States)

    Burschka, Julian; Dualeh, Amalie; Kessler, Florian; Baranoff, Etienne; Cevey-Ha, Ngoc-Lê; Yi, Chenyi; Nazeeruddin, Mohammad K; Grätzel, Michael

    2011-11-16

    Chemical doping is an important strategy to alter the charge-transport properties of both molecular and polymeric organic semiconductors that find widespread application in organic electronic devices. We report on the use of a new class of Co(III) complexes as p-type dopants for triarylamine-based hole conductors such as spiro-MeOTAD and their application in solid-state dye-sensitized solar cells (ssDSCs). We show that the proposed compounds fulfill the requirements for this application and that the discussed strategy is promising for tuning the conductivity of spiro-MeOTAD in ssDSCs, without having to rely on the commonly employed photo-doping. By using a recently developed high molar extinction coefficient organic D-π-A sensitizer and p-doped spiro-MeOTAD as hole conductor, we achieved a record power conversion efficiency of 7.2%, measured under standard solar conditions (AM1.5G, 100 mW cm(-2)). We expect these promising new dopants to find widespread applications in organic electronics in general and photovoltaics in particular.

  4. Tris(2-(1 H -pyrazol-1-yl)pyridine)cobalt(III) as p-Type Dopant for Organic Semiconductors and Its Application in Highly Efficient Solid-State Dye-Sensitized Solar Cells

    KAUST Repository

    Burschka, Julian

    2011-11-16

    Chemical doping is an important strategy to alter the charge-transport properties of both molecular and polymeric organic semiconductors that find widespread application in organic electronic devices. We report on the use of a new class of Co(III) complexes as p-type dopants for triarylamine-based hole conductors such as spiro-MeOTAD and their application in solid-state dye-sensitized solar cells (ssDSCs). We show that the proposed compounds fulfill the requirements for this application and that the discussed strategy is promising for tuning the conductivity of spiro-MeOTAD in ssDSCs, without having to rely on the commonly employed photo-doping. By using a recently developed high molar extinction coefficient organic D-π-A sensitizer and p-doped spiro-MeOTAD as hole conductor, we achieved a record power conversion efficiency of 7.2%, measured under standard solar conditions (AM1.5G, 100 mW cm -2). We expect these promising new dopants to find widespread applications in organic electronics in general and photovoltaics in particular. © 2011 American Chemical Society.

  5. Methods for forming group III-arsenide-nitride semiconductor materials

    Science.gov (United States)

    Major, Jo S. (Inventor); Welch, David F. (Inventor); Scifres, Donald R. (Inventor)

    2002-01-01

    Methods are disclosed for forming Group III-arsenide-nitride semiconductor materials. Group III elements are combined with group V elements, including at least nitrogen and arsenic, in concentrations chosen to lattice match commercially available crystalline substrates. Epitaxial growth of these III-V crystals results in direct bandgap materials, which can be used in applications such as light emitting diodes and lasers. Varying the concentrations of the elements in the III-V crystals varies the bandgaps, such that materials emitting light spanning the visible spectra, as well as mid-IR and near-UV emitters, can be created. Conversely, such material can be used to create devices that acquire light and convert the light to electricity, for applications such as full color photodetectors and solar energy collectors. The growth of the III-V crystals can be accomplished by growing thin layers of elements or compounds in sequences that result in the overall lattice match and bandgap desired.

  6. Methods for the additive manufacturing of semiconductor and crystal materials

    Science.gov (United States)

    Stowe, Ashley C.; Speight, Douglas

    2016-11-22

    A method for the additive manufacturing of inorganic crystalline materials, including: physically combining a plurality of starting materials that are used to form an inorganic crystalline compound to be used as one or more of a semiconductor, scintillator, laser crystal, and optical filter; heating or melting successive regions of the combined starting materials using a directed heat source having a predetermined energy characteristic, thereby facilitating the reaction of the combined starting materials; and allowing each region of the combined starting materials to cool in a controlled manner, such that the desired inorganic crystalline compound results. The method also includes, prior to heating or melting the successive regions of the combined starting materials using the directed heat source, heating the combined starting materials to facilitate initial reaction of the combined starting materials. The method further includes translating the combined starting materials and/or the directed heat source between successive locations. The method still further includes controlling the mechanical, electrical, photonic, and/or optical properties of the inorganic crystalline compound.

  7. Methods for the additive manufacturing of semiconductor and crystal materials

    Energy Technology Data Exchange (ETDEWEB)

    Stowe, Ashley C.; Speight, Douglas

    2016-11-22

    A method for the additive manufacturing of inorganic crystalline materials, including: physically combining a plurality of starting materials that are used to form an inorganic crystalline compound to be used as one or more of a semiconductor, scintillator, laser crystal, and optical filter; heating or melting successive regions of the combined starting materials using a directed heat source having a predetermined energy characteristic, thereby facilitating the reaction of the combined starting materials; and allowing each region of the combined starting materials to cool in a controlled manner, such that the desired inorganic crystalline compound results. The method also includes, prior to heating or melting the successive regions of the combined starting materials using the directed heat source, heating the combined starting materials to facilitate initial reaction of the combined starting materials. The method further includes translating the combined starting materials and/or the directed heat source between successive locations. The method still further includes controlling the mechanical, electrical, photonic, and/or optical properties of the inorganic crystalline compound.

  8. Thermoelectric properties of p-type (Bi0.15Sb0.85)2Te3-PbTe graded thermoelectric materials with different barriers

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    The p-type (Bi0.15Sb0.85)2Te3 and PbTe are typical thermoelectric materials used for low and middle temperature range and functional graded materials (FGM) is an inevitable way to widen the working temperature range. Here two segments graded thermoelectric materials (GTM) consisting of (Bi0.15Sb0.85)2Te3, PbTe and different barriers were fabricated by the common hot pressure method. Metals Fe, Mg and Ni were used as barriers between the two segments. The diffusion of different barriers between the barriers and bases were analyzed by electron microprobe analysis (EMA). The phase and crystal structures were determined by X-ray diffraction analysis (XRD). The thermoelectric properties were measured at 303 K along the direction parallel to the pressing direction.The results show that the compositional diffusion occurs when there is no barrier at the interface of the two segments, and the diffusion of Pb is most obvious; as the barrier material, the diffusion of metals Fe, Mg and Ni between different bases is not very obvious,and the thermoelectric properties of GTM is much better than that of the original segment.

  9. High-performance green semiconductor devices: materials, designs, and fabrication

    Science.gov (United States)

    Jung, Yei Hwan; Zhang, Huilong; Gong, Shaoqin; Ma, Zhenqiang

    2017-06-01

    From large industrial computers to non-portable home appliances and finally to light-weight portable gadgets, the rapid evolution of electronics has facilitated our daily pursuits and increased our life comforts. However, these rapid advances have led to a significant decrease in the lifetime of consumer electronics. The serious environmental threat that comes from electronic waste not only involves materials like plastics and heavy metals, but also includes toxic materials like mercury, cadmium, arsenic, and lead, which can leak into the ground and contaminate the water we drink, the food we eat, and the animals that live around us. Furthermore, most electronics are comprised of non-renewable, non-biodegradable, and potentially toxic materials. Difficulties in recycling the increasing amount of electronic waste could eventually lead to permanent environmental pollution. As such, discarded electronics that can naturally degrade over time would reduce recycling challenges and minimize their threat to the environment. This review provides a snapshot of the current developments and challenges of green electronics at the semiconductor device level. It looks at the developments that have been made in an effort to help reduce the accumulation of electronic waste by utilizing unconventional, biodegradable materials as components. While many semiconductors are classified as non-biodegradable, a few biodegradable semiconducting materials exist and are used as electrical components. This review begins with a discussion of biodegradable materials for electronics, followed by designs and processes for the manufacturing of green electronics using different techniques and designs. In the later sections of the review, various examples of biodegradable electrical components, such as sensors, circuits, and batteries, that together can form a functional electronic device, are discussed and new applications using green electronics are reviewed.

  10. Progress Made in the Studies of Novel Materials for Organic Semiconductors

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    @@ Co-funded by NSFC, Ministry of Science & Technology of China (MOST) and the Chinese Academy of Sciences (CAS), researchers at the Key Laboratory of Organic Solids, ICCAS, made progress in designing and synthesis of n- and p-type organic semiconductors.

  11. Material Engineering for Monolithic Semiconductor Mode-Locked Lasers

    DEFF Research Database (Denmark)

    Kulkova, Irina

    This thesis is devoted to the materials engineering for semiconductor monolithic passively mode-locked lasers (MLLs) as a compact energy-efficient source of ultrashort optical pulses. Up to the present day, the achievement of low-noise sub-picosecond pulse generation has remained a challenge....... This work has considered the role of the combined ultrafast gain and absorption dynamics in MLLs as a main factor limiting laser performance. An independent optimization of MLL amplifier and saturable absorber active materials was performed. Two promising approaches were considered: quantum dot (QD...... application in MLLs. Improved QW laser performance was demonstrated using the asymmetric barrier layer approach. The analysis of the gain characteristics showed that the high population inversion beneficial for noise reduction cannot be achieved for 10 GHz QW MLLs and would have required lowering the modal...

  12. Materials science: Screen printing of 2D semiconductors

    Science.gov (United States)

    Kim, Young Duck; Hone, James

    2017-04-01

    Atomically thin semiconductors have been made by transferring the oxide 'skin' of a liquid metal to substrates. This opens the way to the low-cost mass production of 2D semiconductors at the sizes needed for electronics applications.

  13. Binary copper oxide semiconductors: From materials towards devices

    Energy Technology Data Exchange (ETDEWEB)

    Meyer, B.K.; Polity, A.; Reppin, D.; Becker, M.; Hering, P.; Klar, P.J.; Sander, T.; Reindl, C.; Benz, J.; Eickhoff, M.; Heiliger, C.; Heinemann, M. [1. Physics Institute, Justus-Liebig University of Giessen (Germany); Blaesing, J.; Krost, A. [Institute of Experimental Physics (IEP), Otto-von-Guericke University Magdeburg (Germany); Shokovets, S. [Institute of Physics, Ilmenau University of Technology (Germany); Mueller, C.; Ronning, C. [Institute of Solid State Physics, Friedrich Schiller University Jena (Germany)

    2012-08-15

    Copper-oxide compound semiconductors provide a unique possibility to tune the optical and electronic properties from insulating to metallic conduction, from bandgap energies of 2.1 eV to the infrared at 1.40 eV, i.e., right into the middle of the efficiency maximum for solar-cell applications. Three distinctly different phases, Cu{sub 2}O, Cu{sub 4}O{sub 3}, and CuO, of this binary semiconductor can be prepared by thin-film deposition techniques, which differ in the oxidation state of copper. Their material properties as far as they are known by experiment or predicted by theory are reviewed. They are supplemented by new experimental results from thin-film growth and characterization, both will be critically discussed and summarized. With respect to devices the focus is on solar-cell performances based on Cu{sub 2}O. It is demonstrated by photoelectron spectroscopy (XPS) that the heterojunction system p-Cu{sub 2}O/n-AlGaN is much more promising for the application as efficient solar cells than that of p-Cu{sub 2}O/n-ZnO heterojunction devices that have been favored up to now. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  14. Methods of use of semiconductor nanocrystal probes for treating a material

    Science.gov (United States)

    Weiss, Shimon; Bruchez, Marcel; Alivisatos, Paul

    2007-04-27

    A semiconductor nanocrystal compound and probe are described. The compound is capable of linking to one or more affinity molecules. The compound comprises (1) one or more semiconductor nanocrystals capable of, in response to exposure to a first energy, providing a second energy, and (2) one or more linking agents, having a first portion linked to one or more semiconductor nanocrystals and a second portion capable of linking to one or more affinity molecules. One or more semiconductor nanocrystal compounds are linked to one or more affinity molecules to form a semiconductor nanocrystal probe capable of bonding with one or more detectable substances in a material being analyzed, and capable of, in response to exposure to a first energy, providing a second energy. Also described are processes for respectively: making the semiconductor nanocrystal compound; making the semiconductor nanocrystal probe; and treating materials with the probe.

  15. Hydrogen-bond Specific Materials Modification in Group IV Semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    Tolk, Norman H. [Vanderbilt Univ., Nashville, TN (United States); Feldman, L. C. [Vanderbilt Univ., Nashville, TN (United States); Luepke, G. [College of William and Mary, Williamsburg, VA (United States)

    2015-09-14

    Executive summary Semiconductor dielectric crystals consist of two fundamental components: lattice atoms and electrons. The former component provides a crystalline structure that can be disrupted by various defects or the presence of an interface, or by transient oscillations known as phonons. The latter component produces an energetic structure that is responsible for the optical and electronic properties of the material, and can be perturbed by lattice defects or by photo-excitation. Over the period of this project, August 15, 1999 to March 31, 2015, a persistent theme has been the elucidation of the fundamental role of defects arising from the presence of radiation damage, impurities (in particular, hydrogen), localized strain or some combination of all three. As our research effort developed and evolved, we have experienced a few title changes, which reflected this evolution. Throughout the project, ultrafast lasers usually in a pump-probe configuration provided the ideal means to perturb and study semiconductor crystals by both forms of excitation, vibrational (phonon) and electronic (photon). Moreover, we have found in the course of this research that there are many interesting and relevant scientific questions that may be explored when phonon and photon excitations are controlled separately. Our early goals were to explore the dynamics of bond-selective vibrational excitation of hydrogen from point defects and impurities in crystalline and amorphous solids, initiating an investigation into the behavior of hydrogen isotopes utilizing a variety of ultrafast characterization techniques, principally transient bleaching spectroscopy to experimentally obtain vibrational lifetimes. The initiative could be divided into three related areas: (a) investigation of the change in electronic structure of solids due to the presence of hydrogen defect centers, (b) dynamical studies of hydrogen in materials and (c) characterization and stability of metastable hydrogen

  16. MATERIAL ELEMENT MODEL FOR EXTRINSIC SEMICONDUCTORS WITH DEFECTS OF DISLOCATION

    Directory of Open Access Journals (Sweden)

    Maria Paola Mazzeo

    2011-07-01

    Full Text Available In a previous paper we outlined a geometric model for the thermodynamic description of extrinsic semiconductors with defects of dislocation.Applying a geometrization technique, within the rationalextended irreversible thermodynamics with internal variables, the dynamical system for simple material elements of these media, the expressions of the entropy function and the entropy 1-form were obtained. In this contribution we deepen the study of this geometric model. We give a detailed description of the defective media under consideration and of the dislocation core tensor, we introduce the transformation induced by the process and, applying the closure conditions for the entropy 1-form, we derive the necessary conditions for the existence of the entropy function. These and other results are new in the paper.The derivation of the relevant entropy 1-form is the starting point to introduce an extended thermodynamical phase space.

  17. Bipolar magnetic semiconductors: a new class of spintronics materials.

    Science.gov (United States)

    Li, Xingxing; Wu, Xiaojun; Li, Zhenyu; Yang, Jinlong; Hou, J G

    2012-09-21

    Electrical control of spin polarization is very desirable in spintronics, since electric fields can be easily applied locally, in contrast to magnetic fields. Here, we propose a new concept of bipolar magnetic semiconductors (BMS) in which completely spin-polarized currents with reversible spin polarization can be created and controlled simply by applying a gate voltage. This is a result of the unique electronic structure of BMS, where the valence and conduction bands possess opposite spin polarization when approaching the Fermi level. BMS is thus expected to have potential for various applications. Our band structure and spin-polarized electronic transport calculations on semi-hydrogenated single-walled carbon nanotubes confirm the existence of BMS materials and demonstrate the electrical control of spin-polarization in them.

  18. Efficient bifacial perovskite solar cell based on a highly transparent poly(3,4-ethylenedioxythiophene) as the p-type hole-transporting material

    Science.gov (United States)

    Xiao, Yaoming; Han, Gaoyi; Wu, Jihuai; Lin, Jeng-Yu

    2016-02-01

    A novel bifacial perovskite solar cell (PSC) is devised and prepared by using a highly transparent poly(3,4-ethylenedioxythiophene) (PEDOT) electrode. The PEDOT is used as the p-type hole-transporting material (HTM) due to the well matched band positions for the charge separation and transport. Moreover, the PEDOT layer can play a role of electron blocking layer at the CH3NH3PbI3/PEDOT interface to reduce the electron recombination rate because of its LUMO level is higher than that of the perovskite sensitizer. As a result, the bifacial PSC based on the PEDOT HTM yields front and rear efficiencies of 12.33% and 11.78% respectively, which are higher than those of the PSC without the PEDOT HTM (8.67% and 8.27% of the front and rear efficiencies). And the front efficiency is only decreased by 4.46% to the rear efficiency. These promising results highlight the potential application of the PEDOT in the cost-effective and transparent PSC, which could be used in the bifacial solar cell and tandem solar cell.

  19. Group IV all-semiconductor spintronics. Materials aspects and optical spin selection rules

    Energy Technology Data Exchange (ETDEWEB)

    Sircar, Narayan

    2012-04-03

    In the scope of the present thesis various aspects for the realization of spintronic applications based on group IV semiconductors are discussed. This work comprises a refined material characterization of the magnetic semiconductor GeMn. We furthermore present efforts to utilize this material as spin injector for a Si-based optical spintronic device. Applying transmission electron microscopy and atom probe tomography, we are able to resolve a vertical anisotropy in the self-assembly, leading to the stacking of well-defined clusters in the growth direction. Three-dimensional atom distribution maps confirm that clusters are built from a nonstoichiometric GeMn alloy and exhibit a high-Mn-concentration core with a decreasing Mn concentration toward a shell. An amorphous nature of the cluster cores as well as the crystallinity of the shells, coherent with the surrounding Ge lattice, are revealed in scanning transmission electron microscopy. We localize a strain field surrounding each GeMn cluster by scanning transmission electron microscopy. The importance of strain to the stacking phenomenon of the clusters becomes clear in studies of Ge/GeMn superlattice structures, where a vertical spatial correlation of clusters over 30 nm-thick Ge spacer layers is observed. We present evidence that electrical transport properties of the p-type GeMn thin films fabricated on high-resistivity Ge substrates are severely influenced by parallel conduction through the substrate. It is shown that substrate conduction persists also for wellconducting degenerate p-type reference thin films, giving rise to an effective two-layer conduction scheme. GeMn thin films fabricated on these substrates exhibit only a negligible magnetoresistance effect. Before integrating GeMn in an optical spintronic device, some key aspects important for an understanding of the optical injection and detection of carrier spins in Si and Si-based heterostructures are clarified in the second part of this thesis. In

  20. Dopant type and/or concentration selective dry photochemical etching of semiconductor materials

    Energy Technology Data Exchange (ETDEWEB)

    Ashby, C.I.H.; Dishman, J.L.

    1987-03-10

    A method is described of selectively photochemically dry etching a first semiconductor material of a given composition in the presence of a second semiconductor material which is of a composition different from the first material. The second material is not substantially etched during the method which comprises: subjecting both materials to the same photon flux of an energy greater than their respective direct bandgaps and to the same gaseous chemical etchant under conditions where the etchant would be ineffective for chemical etching of either material where the photons not present, the conditions also being such that the resultant electronic structure of the first semiconductor material under the photon flux is sufficient for the first material to undergo substantial photochemical etching under the conditions. The conditions also are such that the resultant electronic structure of the second semiconductor material under the photon flux is not sufficient for the second material to undergo substantial photochemical etching under the conditions.

  1. Semiconductor Nanowires from Materials Science and Device Physics Perspectives

    Science.gov (United States)

    Samuelson, Lars

    2005-03-01

    Realization of extremely down-scaled devices gives tough challenges related to technology and materials science. One reason for the concern is that top-down fabricated nano-devices tend to have their properties dominated by process-induced damage, rendering ultra-small devices not so useful. Alternatively, bottom-up fabrication methods may allow dimensions on the scale even below 10 nm, still with superb device properties. I will in this talk describe our research on catalytically induced growth of semiconductor nanowires. Our method uses catalytic gold nanoparticles, allowing tight control of diameter as well as position of where the nanowire grows, with our work completely focused on epitaxially nucleated nanowires in which the nanowire structure can be seen as a coherent, monolithic extension of the crystalline substrate material. One of the most important achievements in this field of research is the realization of atomically abrupt heterostructures within nanowires, in which the material composition can be altered within only one or a few monolayers, thus allowing 1D heterostructure devices to be realized. This has allowed a variety of quantum devices to be realized, such as single-electron transistors, resonant tunneling devices as well as memory storage devices. A related recent field of progress has been the realization of ideally nucleated III-V nanowires on Si substrates, cases where we have also reported functioning III-V heterostructure device structures on Si. All of these device related challenges evolve from an improved understanding of the materials science involved in nucleation of nanowires, in altering of composition of the growing nanowire, in control of the growth direction etc. I will give examples of these materials science issues and will especially dwell on the opportunities to form new kinds of materials, e.g. as 3D complex nanowire structures, resembling nanotrees or nanoforests.

  2. III-V aresenide-nitride semiconductor materials and devices

    Science.gov (United States)

    Major, Jo S. (Inventor); Welch, David F. (Inventor); Scifres, Donald R. (Inventor)

    1997-01-01

    III-V arsenide-nitride semiconductor crystals, methods for producing such crystals and devices employing such crystals. Group III elements are combined with group V elements, including at least nitrogen and arsenic, in concentrations chosen to lattice match commercially available crystalline substrates. Epitaxial growth of these III-V crystals results in direct bandgap materials, which can be used in applications such as light emitting diodes and lasers. Varying the concentrations of the elements in the III-V crystals varies the bandgaps, such that materials emitting light spanning the visible spectra, as well as mid-IR and near-UV emitters, can be created. Conversely, such material can be used to create devices that acquire light and convert the light to electricity, for applications such as full color photodetectors and solar energy collectors. The growth of the III-V crystals can be accomplished by growing thin layers of elements or compounds in sequences that result in the overall lattice match and bandgap desired.

  3. Hydrogen-bond Specific Materials Modification in Group IV Semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    Tolk, Norman H. [Vanderbilt Univ., Nashville, TN (United States); Feldman, L. C. [Vanderbilt Univ., Nashville, TN (United States); Luepke, G. [College of William and Mary, Williamsburg, VA (United States)

    2015-09-14

    Executive summary Semiconductor dielectric crystals consist of two fundamental components: lattice atoms and electrons. The former component provides a crystalline structure that can be disrupted by various defects or the presence of an interface, or by transient oscillations known as phonons. The latter component produces an energetic structure that is responsible for the optical and electronic properties of the material, and can be perturbed by lattice defects or by photo-excitation. Over the period of this project, August 15, 1999 to March 31, 2015, a persistent theme has been the elucidation of the fundamental role of defects arising from the presence of radiation damage, impurities (in particular, hydrogen), localized strain or some combination of all three. As our research effort developed and evolved, we have experienced a few title changes, which reflected this evolution. Throughout the project, ultrafast lasers usually in a pump-probe configuration provided the ideal means to perturb and study semiconductor crystals by both forms of excitation, vibrational (phonon) and electronic (photon). Moreover, we have found in the course of this research that there are many interesting and relevant scientific questions that may be explored when phonon and photon excitations are controlled separately. Our early goals were to explore the dynamics of bond-selective vibrational excitation of hydrogen from point defects and impurities in crystalline and amorphous solids, initiating an investigation into the behavior of hydrogen isotopes utilizing a variety of ultrafast characterization techniques, principally transient bleaching spectroscopy to experimentally obtain vibrational lifetimes. The initiative could be divided into three related areas: (a) investigation of the change in electronic structure of solids due to the presence of hydrogen defect centers, (b) dynamical studies of hydrogen in materials and (c) characterization and stability of metastable hydrogen

  4. Analysis of Interface Charge Densities for High-k Dielectric Materials based Metal Oxide Semiconductor Devices

    Science.gov (United States)

    Maity, N. P.; Thakur, R. R.; Maity, Reshmi; Thapa, R. K.; Baishya, S.

    2016-10-01

    In this paper, the interface charge densities (Dit) are studied and analyzed for ultra thin dielectric metal oxide semiconductor (MOS) devices using different high-k dielectric materials such as Al2O3, ZrO2 and HfO2. The Dit have been calculated by a new approach using conductance method and it indicates that by reducing the thickness of the oxide, the Dit increases and similar increase is also found by replacing SiO2 with high-k. For the same oxide thickness, SiO2 has the lowest Dit and found to be the order of 1011cm-2eV-1. Linear increase in Dit has been observed as the dielectric constant of the oxide increases. The Dit is found to be in good agreement with published fabrication results at p-type doping level of 1×1017cm-3. Numerical calculations and solutions are performed by MATLAB and device simulation is done by ATLAS.

  5. Investigation of L-cystine assisted Cu3BiS 3 synthesis for energetically and environmentally improved integration as thin-film solar cell p-type semiconductor absorber

    Science.gov (United States)

    Viezbicke, Brian D.

    Solar photovoltaic energy technology is increasingly implemented in response to continuously growing global energy needs. While legacy technology utilizing silicon has captured much of the market, thin-film solar modules are projected to rise particularly in the U.S. production sector. Current materials utilized in production and deployment encounter resource and environmental impact constraints. This research investigates the viably controllable synthesis of multi-crystalline copper bismuth sulfide for potential use as an absorber layer in thin-film solar cells and early investigation of thin-film growth parameters which may enable a cost-effective route to full scale production of epitaxial copper bismuth sulfide films. The first step of this investigation has entailed a novel route for the solvo-thermally grown Cu3BiS 3 films facilitated by L-cystine as a sulfur donating and complexing agent. In the characterization of the nanoparticulate product UV-VIS spectra were analyzed via the Tauc method of bandgap interpolation. The validity of the Tauc method in application to polycrystalline films has been investigated and proven to be robust for the material class. This justifies the bandgap assessment of the subject material and provides support for wider use of the method. With the synthesis method established, the reaction was transferred to a custom built continuous flow reactor to explore this process and help understand its capabilities and limits with respect to producing single layers for an eventual photovoltaic cell stack. Though the published work has established novel chemistry, the need to deposit and/or grow a functional p-type layer for further characterization and eventual device incorporation is key to the material evolution. First evidence of continuous flow micro-reactor deposition of Cu3BiS3 has been shown with an array of resulting microstructures. The grown microstructures are evaluated with relevance to prior synthesis laboratory procedure and

  6. Hall and thermoelectric evaluation of p-type InAs

    Energy Technology Data Exchange (ETDEWEB)

    Wagener, M.C., E-mail: magnus.wagener@nmmu.ac.z [Department of Physics, Nelson Mandela Metropolitan University, Port Elizabeth (South Africa); Wagener, V.; Botha, J.R. [Department of Physics, Nelson Mandela Metropolitan University, Port Elizabeth (South Africa)

    2009-12-15

    This paper compares the galvanometric and thermoelectric evaluation of the electrical characteristics of narrow gap semiconductors. In particular, the influence of a surface inversion layer is incorporated into the analysis of the temperature-dependent Hall and thermoelectric measurements of p-type InAs. The temperature at which the Seebeck coefficient of p-type material changes sign is shown to be unaffected by the presence of degenerate conduction paths. This finding consequently facilitated the direct determination of the acceptor density of lightly doped thin film InAs.

  7. Possible lattice formation of new materials within a piezoelectric semiconductor plasma

    Indian Academy of Sciences (India)

    M Salimullah; S Ghosh; M R Amin

    2000-05-01

    The possible lattice formation of grains of chosen material in a magnetized current carrying -type piezoelectric semiconductor plasma has been examined. In addition to the repulsive Coulomb potential, there appears a non-Coulombic oscillatory potential among the highly charged grains due to the strong resonant collective interaction of the grains and the electron-acoustic mode of the host semiconductor giving rise to the possibility of the lattice formation of grains of new materials.

  8. Novel semiconductor materials for the development of chemical sensors and biosensors: A review

    Energy Technology Data Exchange (ETDEWEB)

    Chaniotakis, Nikos [Laboratory of Analytical Chemistry, Department of Chemistry, University of Crete, Voutes 71003 Iraklion, Crete (Greece)], E-mail: nchan@chemistry.uoc.gr; Sofikiti, Nikoletta [Laboratory of Analytical Chemistry, Department of Chemistry, University of Crete, Voutes 71003 Iraklion, Crete (Greece)

    2008-05-12

    The aim of this manuscript is to provide a condensed overview of the contribution of certain relatively new semiconductor substrates in the development of chemical and biochemical field effect transistors. The silicon era is initially reviewed providing the background onto which the deployment of the new semiconductor materials for the development of bio-chem-FETs is based on. Subsequently emphasis is given to the selective interaction of novel semiconductor surfaces, including doped conductive diamond, gallium nitride, and indium nitride, with the analyte, and how this interaction can be properly transduced using semiconductor technology. The main advantages and drawbacks of these materials, as well as their future prospects for their applications in the sensor area are also described.

  9. Materials chemistry. Composition-matched molecular "solders" for semiconductors.

    Science.gov (United States)

    Dolzhnikov, Dmitriy S; Zhang, Hao; Jang, Jaeyoung; Son, Jae Sung; Panthani, Matthew G; Shibata, Tomohiro; Chattopadhyay, Soma; Talapin, Dmitri V

    2015-01-23

    We propose a general strategy to synthesize largely unexplored soluble chalcogenidometallates of cadmium, lead, and bismuth. These compounds can be used as "solders" for semiconductors widely used in photovoltaics and thermoelectrics. The addition of solder helped to bond crystal surfaces and link nano- or mesoscale particles together. For example, CdSe nanocrystals with Na2Cd2Se3 solder was used as a soluble precursor for CdSe films with electron mobilities exceeding 300 square centimeters per volt-second. CdTe, PbTe, and Bi2Te3 powders were molded into various shapes in the presence of a small additive of composition-matched chalcogenidometallate or chalcogel, thus opening new design spaces for semiconductor technologies.

  10. Methods of measurement for semiconductor materials, process control, and devices

    Science.gov (United States)

    Bullis, W. M. (Editor)

    1972-01-01

    Significant accomplishments include development of a procedure to correct for the substantial differences of transistor delay time as measured with different instruments or with the same instrument at different frequencies; association of infrared response spectra of poor quality germanium gamma ray detectors with spectra of detectors fabricated from portions of a good crystal that had been degraded in known ways; and confirmation of the excellent quality and cosmetic appearance of ultrasonic bonds made with aluminum ribbon wire. Work is continuing on measurement of resistivity of semiconductor crystals; study of gold-doped silicon, development of the infrared response technique; evaluation of wire bonds and die attachment; and measurement of thermal properties of semiconductor devices, delay time and related carrier transport properties in junction devices, and noise properties of microwave diodes.

  11. Maxwell-Bloch Equations Modeling of Ultrashort Optical Pulse Propagation in Semiconductor Materials

    Science.gov (United States)

    Goorjian, Peter M.; Agrawal, Govind, P.

    1997-01-01

    An algorithm has been developed that solves the semiconductor Maxwell-Bloch equations, without making the standard slowly-varying envelope (SVEA) and rotating-wave (RWA) approximations. It is applied to study the propagation of ultrashort pulses in semiconductor materials. The results include many-body effects due to the Coulomb interaction among the charge carriers as well as the nonlinear effects resulting from spectral hole-burning.

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

    Science.gov (United States)

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

    2016-10-01

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

  13. Neutron detection using boron gallium nitride semiconductor material

    OpenAIRE

    Katsuhiro Atsumi; Yoku Inoue; Hidenori Mimura; Toru Aoki; Takayuki Nakano

    2014-01-01

    In this study, we developed a new neutron-detection device using a boron gallium nitride (BGaN) semiconductor in which the B atom acts as a neutron converter. BGaN and gallium nitride (GaN) samples were grown by metal organic vapor phase epitaxy, and their radiation detection properties were evaluated. GaN exhibited good sensitivity to α-rays but poor sensitivity to γ-rays. Moreover, we confirmed that electrons were generated in the depletion layer under neutron irradiation. This resulted in ...

  14. Emission energy control of semiconductor quantum dots using phase change material

    Science.gov (United States)

    Kanazawa, Shohei; Sato, Yu; Yamamura, Ariyoshi; Saiki, Toshiharu

    2015-03-01

    Semiconductor quantum dots have paid much attention as it is a promising candidate for quantum, optical devices, such as quantum computer and quantum dot laser. We propose a local emission energy control method of semiconductor quantum dots using applying strain by volume expansion of phase change material. Phase change material can change its phase crystalline to amorphous, and the volume expand by its phase change. This method can control energy shift direction and amount by amorphous religion and depth. Using this method, we matched emission energy of two InAs/InP quantum dots. This achievement can connect to observing superradiance phenomenon and quantum dot coupling effect.

  15. What can be expected from high-Z semiconductor detectors. [Assessment of promising semiconductor materials; 25 references

    Energy Technology Data Exchange (ETDEWEB)

    Armantrout, G.A.; Swierkowski, S.P.; Sherohman, J.W.; Lee, J.H.

    1976-11-17

    It has been hoped that high-Z semiconductors would offer efficient ..gamma..-ray detection at or near ambient temperatures with energy resolution significantly better than NaI (Tl) scintillators. For use at X-ray energies, this goal has been achieved with both HgI/sub 2/, CdTe, and GaAs detectors. However, at higher energies (approximately 660 keV) all current detectors have one or more significant deficiencies in terms of attainable volume, charge collection efficiency, and polarization effects. Starting with first principles, all potential compounds which can be formed by the binary combination of elements from the periodic chart were considered as possible detector materials. A rank-ordered listing of the most promising materials for further development is given as well as an assessment of the prospects for future success. 25 references.

  16. Comparison of Ohmic contact resistances of n- and p-type Ge source/drain and their impact on transport characteristics of Ge metal oxide semiconductor field effect transistors

    Energy Technology Data Exchange (ETDEWEB)

    Oh, Jungwoo, E-mail: jungwoo.oh@sematech.org [SEMATECH, 2706 Montopolis Drive, Austin, TX 78741 (United States); Huang, Jeff [SEMATECH, 2706 Montopolis Drive, Austin, TX 78741 (United States); Chen, Yen-Ting [Universityof Texas, Austin, TX (United States); Ok, Injo [SEMATECH, 2706 Montopolis Drive, Austin, TX 78741 (United States); Jeon, Kanghoon [Universityof California, Berkeley, CA (United States); Lee, Se-Hoon [Universityof Texas, Austin, TX (United States); Sassman, Barry; Loh, Wei-Yip [SEMATECH, 2706 Montopolis Drive, Austin, TX 78741 (United States); Lee, Hi-Deok [Chungnam National University (Korea, Republic of); Ko, Dea-Hong [Yonsei University (Korea, Republic of); Majhi, Prashant; Kirsch, Paul; Jammy, Raj [SEMATECH, 2706 Montopolis Drive, Austin, TX 78741 (United States)

    2011-10-31

    We report the results of a systematic study to understand low drive current of Ge-nMOSFET (metal-oxide-semiconductor field-effect transistor). The poor electron transport property is primarily attributed to the low dopant activation efficiency and high contact resistance. Results are supported by analyzing source/drain Ohmic metal contacts to n-type Ge using the transmission line method. Ni contacts to Ge nMOSFETs exhibit specific contact resistances of 10{sup -3}-10{sup -5} {Omega} cm{sup 2}, which is significantly higher than the 10{sup -7}-10{sup -8} {Omega} cm{sup 2} of Ni contacts to Ge pMOSFETs. The high resistance of Ni Ohmic contacts to n-type Ge is attributed mainly to insufficient dopant activation in Ge (or high sheet resistance) and a high tunneling barrier. Results obtained in this work identify one of the root causes of the lower than expected Ge nMOSFET transport issue, advancing high mobility Ge channel technology.

  17. Center for Semiconductor Materials and Device Modeling: expanding collaborative research opportunities between government, academia, and industry

    Science.gov (United States)

    Perconti, Philip; Bedair, Sarah S.; Bajaj, Jagmohan; Schuster, Jonathan; Reed, Meredith

    2016-09-01

    To increase Soldier readiness and enhance situational understanding in ever-changing and complex environments, there is a need for rapid development and deployment of Army technologies utilizing sensors, photonics, and electronics. Fundamental aspects of these technologies include the research and development of semiconductor materials and devices which are ubiquitous in numerous applications. Since many Army technologies are considered niche, there is a lack of significant industry investment in the fundamental research and understanding of semiconductor technologies relevant to the Army. To address this issue, the US Army Research Laboratory is establishing a Center for Semiconductor Materials and Device Modeling and seeks to leverage expertise and resources across academia, government and industry. Several key research areas—highlighted and addressed in this paper—have been identified by ARL and external partners and will be pursued in a collaborative fashion by this Center. This paper will also address the mechanisms by which the Center is being established and will operate.

  18. A Study on Photothermal Waves in a Semiconductor Material Photogenerated by a Focused Laser Beam

    Science.gov (United States)

    Abbas, Ibrahim A.; Aly, K. A.

    2016-11-01

    In this work, the theory of coupled plasma, thermal and elastic waves were used to investigate the wave propagation on semiconductor material during photo-thermo-elastic process. A thin slim strip (TSS) medium, elastic semiconductor with isotropic and homogeneous thermal and elastic properties have been considered. The plasma, thermal and elastic waves in a TSS photo generated by a focused and intensity modulated laser beam were analyzed. Laplace transform techniques and eigenvalue approach were used to obtain the analytical solutions for carrier density, displacement, temperature, and stress. Numerical computations have been carried out on silicon-like semiconductor material. The results are presented graphically to show the effect of the coupling between the plasma, thermal, and elastic waves.

  19. Method of making macrocrystalline or single crystal semiconductor material

    Science.gov (United States)

    Shlichta, P. J. (Inventor); Holliday, R. J. (Inventor)

    1986-01-01

    A macrocrystalline or single crystal semiconductive material is formed from a primary substrate including a single crystal or several very large crystals of a relatively low melting material. This primary substrate is deposited on a base such as steel or ceramic, and it may be formed from such metals as zinc, cadmium, germanium, aluminum, tin, lead, copper, brass, magnesium silicide, or magnesium stannide. These materials generally have a melting point below about 1000 C and form on the base crystals the size of fingernails or greater. The primary substrate has an epitaxial relationship with a subsequently applied layer of material, and because of this epitaxial relationship, the material deposited on the primary substrate will have essentially the same crystal size as the crystals in the primary substrate. If required, successive layers are formed, each of a material which has an epitaxial relationship with the previously deposited layer, until a layer is formed which has an epitaxial relationship with the semiconductive material. This layer is referred to as the epitaxial substrate, and its crystals serve as sites for the growth of large crystals of semiconductive material. The primary substrate is passivated to remove or otherwise convert it into a stable or nonreactive state prior to deposition of the seconductive material.

  20. Instrumentation for characterizing materials and composed semiconductors for ionizing radiation detectors

    Energy Technology Data Exchange (ETDEWEB)

    Paschoal, Arquimedes J.A.; Leite, Adolfo M.B.; Nazzre, Fabio V.B.; Santos, Luiz A.P. [Centro Regional de Ciencias Nucleares (CRCN/CNEN-PE), Recife, PE (Brazil). Lab. de Instrumentacao Nuclear]. E-mail: lasantos@cnen.gov.br

    2007-07-01

    The purpose of this work is the development of instrumentation for characterizing some type of ionizing radiation detectors. Those detectors are being manufactured by the Nuclear Instrumentation Laboratory at CRCN/Recife and can be used both on photon beam and with particles. Such detectors consist of semiconductor material in the form of films generated by oxide growing or by means of semiconductor material deposition in a substrate. Those materials can be made of metals, semi-metals, composites or semiconductor polymers. Prior to expose those detectors to ionizing radiation, it must be physically and electrically characterized. In this intention it was developed an electromechanical system. An electrical circuit was built to measure the signal from the detector and another circuit to control the movement of four probes (4-points technique) by using a stepper motor and the micro stepping technique avoiding damage to the detector. This system can be of interest to researchers that work with a sort of semiconductor materials in the form of thin film and in nanotechnological processes aiming the design of radiation ionizing detectors. (author)

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

    Science.gov (United States)

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

    2014-02-26

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

  2. Superatoms and Metal-Semiconductor Motifs for Cluster Materials

    Energy Technology Data Exchange (ETDEWEB)

    Castleman, A. W.

    2013-10-11

    A molecular understanding of catalysis and catalytically active materials is of fundamental importance in designing new substances for applications in energy and fuels. We have performed reactivity studies and ultrafast ionization and coulomb explosion studies on a variety of catalytically-relevant materials, including transition metal oxides of Fe, Co, Ni, Cu, Ti, V, Nb, and Ta. We demonstrate that differences in charge state, geometry, and elemental composition of clusters of such materials determine chemical reactivity and ionization behavior, crucial steps in improving performance of catalysts.

  3. Hydrogenated bilayer wurtzite SiC nanofilms: a two-dimensional bipolar magnetic semiconductor material.

    Science.gov (United States)

    Yuan, Long; Li, Zhenyu; Yang, Jinlong

    2013-01-14

    Recently, a new kind of spintronics material, bipolar magnetic semiconductors (BMS), has been proposed. The spin polarization of BMS can be conveniently controlled by a gate voltage, which makes it very attractive in device engineering. Now, the main challenge is finding more BMS materials. In this article, we propose that hydrogenated wurtzite SiC nanofilm is a two-dimensional BMS material. Its BMS character is very robust under the effect of strain, substrate or even a strong electric field. The proposed two-dimensional BMS material paves the way to use this promising new material in an integrated circuit.

  4. Rhombohedral cubic semiconductor materials on trigonal substrate with single crystal properties and devices based on such materials

    Science.gov (United States)

    Park, Yeonjoon (Inventor); Choi, Sang Hyouk (Inventor); King, Glen C. (Inventor); Elliott, James R. (Inventor)

    2012-01-01

    Growth conditions are developed, based on a temperature-dependent alignment model, to enable formation of cubic group IV, group II-V and group II-VI crystals in the [111] orientation on the basal (0001) plane of trigonal crystal substrates, controlled such that the volume percentage of primary twin crystal is reduced from about 40% to about 0.3%, compared to the majority single crystal. The control of stacking faults in this and other embodiments can yield single crystalline semiconductors based on these materials that are substantially without defects, or improved thermoelectric materials with twinned crystals for phonon scattering while maintaining electrical integrity. These methods can selectively yield a cubic-on-trigonal epitaxial semiconductor material in which the cubic layer is substantially either directly aligned, or 60 degrees-rotated from, the underlying trigonal material.

  5. Biasing, operation and parasitic current limitation in single device equivalent to CMOS, and other semiconductor systems

    Science.gov (United States)

    Welch, James D.

    2003-09-23

    Disclosed are semiconductor devices including at least one junction which is rectifying whether the semiconductor is caused to be N or P-type, by the presence of applied gate voltage field induced carriers in essentially intrinsic, essentially homogeneously simultaneously containing both N and P-type metallurgical dopants at substantially equal doping levels, essentially homogeneously simultaneously containing both N and P-type metallurgical dopants at different doping levels, and containing a single metallurgical doping type, and functional combinations thereof. In particular, inverting and non-inverting gate voltage channel induced semiconductor single devices with operating characteristics similar to conventional multiple device CMOS systems, which can be operated as modulators, are disclosed as are a non-latching SCR and an approach to blocking parasitic currents utilizing material(s) which form rectifying junctions with both N and P-type semiconductor whether metallurigically or field induced.

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

    Energy Technology Data Exchange (ETDEWEB)

    Benecha, E. M. [Department of Physics, University of South Africa, P.O Box 392, UNISA 0003, Pretoria (South Africa); Lombardi, E. B. [College of Graduate Studies, University of South Africa, P.O Box 392, UNISA 0003, Pretoria (South Africa)

    2014-02-21

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

  7. Density functional theory and beyond-opportunities for quantum methods in materials modeling semiconductor technology.

    Science.gov (United States)

    Shankar, Sadasivan; Simka, Harsono; Haverty, Michael

    2008-02-13

    In the semiconductor industry, the use of new materials has been increasing with the advent of nanotechnology. As critical dimensions decrease, and the number of materials increases, the interactions between heterogeneous materials themselves and processing increase in complexity. Traditionally, applications of ab initio techniques are confined to electronic structure and band gap calculations of bulk materials, which are then used in coarse-grained models such as mesoscopic and continuum models. Density functional theory is the most widely used ab initio technique that was successfully extended to several applications. This paper illustrates applications of density functional theory to semiconductor processes and proposes further opportunities for use of such techniques in process development.

  8. The 1.7 kilogram microchip: energy and material use in the production of semiconductor devices.

    Science.gov (United States)

    Williams, Eric D; Ayres, Robert U; Heller, Miriam

    2002-12-15

    The scale of environmental impacts associated with the manufacture of microchips is characterized through analysis of material and energy inputs into processes in the production chain. The total weight of secondary fossil fuel and chemical inputs to produce and use a single 2-gram 32MB DRAM chip are estimated at 1600 g and 72 g, respectively. Use of water and elemental gases (mainly N2) in the fabrication stage are 32,000 and 700 g per chip, respectively. The production chain yielding silicon wafers from quartz uses 160 times the energy required for typical silicon, indicating that purification to semiconductor grade materials is energy intensive. Due to its extremely low-entropy, organized structure, the materials intensity of a microchip is orders of magnitude higher than that of "traditional" goods. Future analysis of semiconductor and other low entropy high-tech goods needs to include the use of secondary materials, especially for purification.

  9. Synthesis and Characterization of Novel Organic Semiconductors

    Institute of Scientific and Technical Information of China (English)

    Prashant; Sonar; Samarendra; P.Singh; Ananth; Dodabalapur; Alan; Sellinger

    2007-01-01

    1 Results Development of new organic semiconductors for use in low-cost,large-area applications is very important for growth of the organic electronic industry.Existing non-polymer based organic semiconductors can be roughly classified into linear,star-shaped,branched or lamellar molecules on the basis of their shape[1]. Generally hole (p-type) and electron (n-type) transporting semiconductors have been prepared from electron donating and accepting π-systems respectively[2]. These materials can be used ...

  10. Enhancement of p-type mobility in tin monoxide by native defects

    KAUST Repository

    Granato, D. B.

    2013-05-31

    Transparent p-type materials with good mobility are needed to build completely transparent p-n junctions. Tin monoxide (SnO) is a promising candidate. A recent study indicates great enhancement of the hole mobility of SnO grown in Sn-rich environment [E. Fortunato et al., Appl. Phys. Lett. 97, 052105 (2010)]. Because such an environment makes the formation of defects very likely, we study defect effects on the electronic structure to explain the increased mobility. We find that Sn interstitials and O vacancies modify the valence band, inducing higher contributions of the delocalized Sn 5p orbitals as compared to the localized O 2p orbitals, thus increasing the mobility. This mechanism of valence band modification paves the way to a systematic improvement of transparent p-type semiconductors.

  11. Preparation and Photovoltaic Properties of p-Type Nano-ZnFe2O4

    Institute of Scientific and Technical Information of China (English)

    LI Zi-heng; ZOU Xu; LI Gen; ZOU Guang-tian

    2012-01-01

    p-Type nano-ZnFe2O4 semiconductors were gained by high-prssure treatment.Surface photovoltaic spectrum(SPS) and transient photovoltaic technology(TPV) were used for studying the photogenerated charge of nano-ZnFe2O4.Results show that the photovoltaic behavior of nano-ZnFe2O4 changed as the processing pressure increased.When the processing pressure was higher than 2 GPa,both SPS response interval and peak changed significantly.XPS results show that the non-lattice oxygen entered into the lattice and the content of lattice oxygen increased with the increase of processing pressure.The material changed from oxygen vacancy type to oxygen excess type and the photoelectric properties changed from n-type to p-type when the processing pressure is higher than 2GPa.

  12. Materials processing threshold report. 1: Semiconductor crystals for infrared detectors

    Science.gov (United States)

    Sager, E. V.; Thompson, T. R.; Nagler, R. G.

    1980-01-01

    An extensive search was performed of the open literature pertaining to infrared detectors to determine what constitutes a good detector and in what way performance is limited by specific material properties. Interviews were conducted with a number of experts in the field to assess their perceptions of the state of the art and of the utility of zero-gravity processing. Based on this information base and on a review of NASA programs in crystal growth and infrared sensors, NASA program goals were reassessed and suggestions are presented as to possible joint and divergent efforts between NASA and DOD.

  13. Nanomembrane-based materials for Group IV semiconductor quantum electronics.

    Science.gov (United States)

    Paskiewicz, D M; Savage, D E; Holt, M V; Evans, P G; Lagally, M G

    2014-02-27

    Strained-silicon/relaxed-silicon-germanium alloy (strained-Si/SiGe) heterostructures are the foundation of Group IV-element quantum electronics and quantum computation, but current materials quality limits the reliability and thus the achievable performance of devices. In comparison to conventional approaches, single-crystal SiGe nanomembranes are a promising alternative as substrates for the epitaxial growth of these heterostructures. Because the nanomembrane is truly a single crystal, in contrast to the conventional SiGe substrate made by compositionally grading SiGe grown on bulk Si, significant improvements in quantum electronic-device reliability may be expected with nanomembrane substrates. We compare lateral strain inhomogeneities and the local mosaic structure (crystalline tilt) in strained-Si/SiGe heterostructures that we grow on SiGe nanomembranes and on compositionally graded SiGe substrates, with micro-Raman mapping and nanodiffraction, respectively. Significant structural improvements are found using SiGe nanomembranes.

  14. Semimetal/Semiconductor Nanocomposites for Thermoelectrics

    Energy Technology Data Exchange (ETDEWEB)

    Lu, Hong [Univ. of California, Santa Barbara, CA (United States). Materials Dept.; Burke, Peter G. [Univ. of California, Santa Barbara, CA (United States). Materials Dept.; Gossard, Arthur C. [Univ. of California, Santa Barbara, CA (United States). Materials Dept.; Zeng, Gehong [Univ. of California, Santa Barbara, CA (United States). Dept. of Electrical and Computer Engineering; Ramu, Ashok T. [Univ. of California, Santa Barbara, CA (United States). Dept. of Electrical and Computer Engineering; Bahk, Je-Hyeong [Univ. of California, Santa Barbara, CA (United States). Dept. of Electrical and Computer Engineering; Bowers, John E. [Univ. of California, Santa Barbara, CA (United States). Dept. of Electrical and Computer Engineering

    2011-04-15

    In this work, we present research on semimetal-semiconductor nanocomposites grown by molecular beam epitaxy (MBE) for thermoelectric applications. We study several different III-V semiconductors embedded with semimetallic rare earth-group V (RE-V) compounds, but focus is given here to ErSb:InxGa1-xSb as a promising p-type thermoelectric material. Nano­structures of RE-V compounds are formed and embedded within the III-V semiconductor matrix. By codoping the nanocomposites with the appropriate dopants, both n-type and p-type materials have been made for thermoelectric applications. The thermoelectric properties have been engineered for enhanced thermoelectric device performance. Segmented thermoelectric power generator modules using 50 μm thick Er-containing nanocomposites have been fabricated and measured. Research on different rare earth elements for thermoelectrics is discussed.

  15. Theory of light propagation in nano-structured materials and semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    Schaarschmidt, M.

    2006-05-03

    This work presents a theory for the propagation of intense electromagnetic radiation in nano-structures materials and semiconductors. One main area is the modelling and simulation of the microscopic material dynamics of low dimensional semiconductors, both structured and bulk, and of a laser induced plasma. The ultrafast microscopic dynamics of these electronic many particle systems under the influence of light fields and scattering mechanisms like electron-electron interaction or interaction with lattice vibrations is described in the density matrix formalism. This description in second quantization yields the temporal nonlocal and nonlinear response of the material to electromagnetic fields. Laser induced plasma in quantum wells will be shown to be a possible new semiconductor source for terahertz-emission (wavelength mm to micrometer). The second focus of interest of this work lies in the simulation of the propagation of electromagnetic waves in different systems like photonic crystals, optical fibers and wave guides. The propagation in bulk semiconductors and waveguides is considered in both slowly varying envelope approximation (SVEA) and with the nonlinear Schroedinger equation. For complex systems like photonic band gap structures with high symmetry a matrix-transfer formalism is applied. For arbitrary structured systems (which may include local breaches of symmetry) a very flexible finite-differences algorithm is employed. The combination of microscopic material dynamics and light propagation enables the calculation of reflection and transmission properties of nano-structured materials not only in linear excitation but also for high intensities where nonlinear light-matter coupling dominates and novel effects arise. One used model system are Bragg-resonant multiple quantum wells. On this one dimensional resonant absorbing photonic crystal new nonlinear effects are studied. Some effect to mention are the possible application as an ultrafast optical switch

  16. CsSnI3: Semiconductor or metal? High electrical conductivity and strong near-infrared photoluminescence from a single material. High hole mobility and phase-transitions.

    Science.gov (United States)

    Chung, In; Song, Jung-Hwan; Im, Jino; Androulakis, John; Malliakas, Christos D; Li, Hao; Freeman, Arthur J; Kenney, John T; Kanatzidis, Mercouri G

    2012-05-23

    CsSnI(3) is an unusual perovskite that undergoes complex displacive and reconstructive phase transitions and exhibits near-infrared emission at room temperature. Experimental and theoretical studies of CsSnI(3) have been limited by the lack of detailed crystal structure characterization and chemical instability. Here we describe the synthesis of pure polymorphic crystals, the preparation of large crack-/bubble-free ingots, the refined single-crystal structures, and temperature-dependent charge transport and optical properties of CsSnI(3), coupled with ab initio first-principles density functional theory (DFT) calculations. In situ temperature-dependent single-crystal and synchrotron powder X-ray diffraction studies reveal the origin of polymorphous phase transitions of CsSnI(3). The black orthorhombic form of CsSnI(3) demonstrates one of the largest volumetric thermal expansion coefficients for inorganic solids. Electrical conductivity, Hall effect, and thermopower measurements on it show p-type metallic behavior with low carrier density, despite the optical band gap of 1.3 eV. Hall effect measurements of the black orthorhombic perovskite phase of CsSnI(3) indicate that it is a p-type direct band gap semiconductor with carrier concentration at room temperature of ∼ 10(17) cm(-3) and a hole mobility of ∼585 cm(2) V(-1) s(-1). The hole mobility is one of the highest observed among p-type semiconductors with comparable band gaps. Its powders exhibit a strong room-temperature near-IR emission spectrum at 950 nm. Remarkably, the values of the electrical conductivity and photoluminescence intensity increase with heat treatment. The DFT calculations show that the screened-exchange local density approximation-derived band gap agrees well with the experimentally measured band gap. Calculations of the formation energy of defects strongly suggest that the electrical and light emission properties possibly result from Sn defects in the crystal structure, which arise

  17. Conjugated polymers/semiconductor nanocrystals hybrid materials--preparation, electrical transport properties and applications.

    Science.gov (United States)

    Reiss, Peter; Couderc, Elsa; De Girolamo, Julia; Pron, Adam

    2011-02-01

    This critical review discusses specific preparation and characterization methods applied to hybrid materials consisting of π-conjugated polymers (or oligomers) and semiconductor nanocrystals. These materials are of great importance in the quickly growing field of hybrid organic/inorganic electronics since they can serve as active components of photovoltaic cells, light emitting diodes, photodetectors and other devices. The electronic energy levels of the organic and inorganic components of the hybrid can be tuned individually and thin hybrid films can be processed using low cost solution based techniques. However, the interface between the hybrid components and the morphology of the hybrid directly influences the generation, separation and transport of charge carriers and those parameters are not easy to control. Therefore a large variety of different approaches for assembling the building blocks--conjugated polymers and semiconductor nanocrystals--has been developed. They range from their simple blending through various grafting procedures to methods exploiting specific non-covalent interactions between both components, induced by their tailor-made functionalization. In the first part of this review, we discuss the preparation of the building blocks (nanocrystals and polymers) and the strategies for their assembly into hybrid materials' thin films. In the second part, we focus on the charge carriers' generation and their transport within the hybrids. Finally, we summarize the performances of solar cells using conjugated polymer/semiconductor nanocrystals hybrids and give perspectives for future developments.

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

    Science.gov (United States)

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

    2013-09-01

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

  19. Compensation of native donor doping in ScN: Carrier concentration control and p-type ScN

    Science.gov (United States)

    Saha, Bivas; Garbrecht, Magnus; Perez-Taborda, Jaime A.; Fawey, Mohammed H.; Koh, Yee Rui; Shakouri, Ali; Martin-Gonzalez, Marisol; Hultman, Lars; Sands, Timothy D.

    2017-06-01

    Scandium nitride (ScN) is an emerging indirect bandgap rocksalt semiconductor that has attracted significant attention in recent years for its potential applications in thermoelectric energy conversion devices, as a semiconducting component in epitaxial metal/semiconductor superlattices and as a substrate material for high quality GaN growth. Due to the presence of oxygen impurities and native defects such as nitrogen vacancies, sputter-deposited ScN thin-films are highly degenerate n-type semiconductors with carrier concentrations in the (1-6) × 1020 cm-3 range. In this letter, we show that magnesium nitride (MgxNy) acts as an efficient hole dopant in ScN and reduces the n-type carrier concentration, turning ScN into a p-type semiconductor at high doping levels. Employing a combination of high-resolution X-ray diffraction, transmission electron microscopy, and room temperature optical and temperature dependent electrical measurements, we demonstrate that p-type Sc1-xMgxN thin-film alloys (a) are substitutional solid solutions without MgxNy precipitation, phase segregation, or secondary phase formation within the studied compositional region, (b) exhibit a maximum hole-concentration of 2.2 × 1020 cm-3 and a hole mobility of 21 cm2/Vs, (c) do not show any defect states inside the direct gap of ScN, thus retaining their basic electronic structure, and (d) exhibit alloy scattering dominating hole conduction at high temperatures. These results demonstrate MgxNy doped p-type ScN and compare well with our previous reports on p-type ScN with manganese nitride (MnxNy) doping.

  20. EDITORIAL: Semiconductor nanotechnology: novel materials and devices for electronics, photonics and renewable energy applications Semiconductor nanotechnology: novel materials and devices for electronics, photonics and renewable energy applications

    Science.gov (United States)

    Goodnick, Stephen; Korkin, Anatoli; Krstic, Predrag; Mascher, Peter; Preston, John; Zaslavsky, Alex

    2010-04-01

    Electronic and photonic information technology and renewable energy alternatives, such as solar energy, fuel cells and batteries, have now reached an advanced stage in their development. Cost-effective improvements to current technological approaches have made great progress, but certain challenges remain. As feature sizes of the latest generations of electronic devices are approaching atomic dimensions, circuit speeds are now being limited by interconnect bottlenecks. This has prompted innovations such as the introduction of new materials into microelectronics manufacturing at an unprecedented rate and alternative technologies to silicon CMOS architectures. Despite the environmental impact of conventional fossil fuel consumption, the low cost of these energy sources has been a long-standing economic barrier to the development of alternative and more efficient renewable energy sources, fuel cells and batteries. In the face of mounting environmental concerns, interest in such alternative energy sources has grown. It is now widely accepted that nanotechnology offers potential solutions for securing future progress in information and energy technologies. The Canadian Semiconductor Technology Conference (CSTC) forum was established 25 years ago in Ottawa as an important symbol of the intrinsic strength of the Canadian semiconductor research and development community, and the Canadian semiconductor industry as a whole. In 2007, the 13th CSTC was held in Montreal, moving for the first time outside the national capital region. The first three meetings in the series of 'Nano and Giga Challenges in Electronics and Photonics'— NGCM2002 in Moscow, NGCM2004 in Krakow, and NGC2007 in Phoenix— were focused on interdisciplinary research from the fundamentals of materials science to the development of new system architectures. In 2009 NGC2009 and the 14th Canadian Semiconductor Technology Conference (CSTC2009) were held as a joint event, hosted by McMaster University (10

  1. P-type transparent conducting oxides

    Science.gov (United States)

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

    2016-09-01

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

  2. Composite THz materials using aligned metallic and semiconductor microwires, experiments and interpretation

    CERN Document Server

    Mazhorova, Anna; Dupuis, Alexandre; Tsuneyuki, Ozaki; Paccianti, Marco; Morandotti, Roberto; Minamide, Hiroaki; Tang, Ming; Wang, Yuye; Ito, Hiromasa; Skorobogatiy, Maksim

    2010-01-01

    We report fabrication method and THz characterization of composite films containing either aligned metallic (tin alloy) microwires or chalcogenide As2Se3 microwires. The microwire arrays are made by stack-and-draw fiber fabrication technique using multi-step co-drawing of low-melting-temperature metals or semiconductor glasses together with polymers. Fibers are then stacked together and pressed into composite films. Transmission through metamaterial films is studied in the whole THz range (0.1-20 THz) using a combination of FTIR and TDS. Metal containing metamaterials are found to have strong polarizing properties, while semiconductor containing materials are polarization independent and could have a designable high refractive index. Using the transfer matrix theory, we show how to retrieve the complex polarization dependent refractive index of the composite films. We then detail the selfconsistent algorithm for retrieving the optical properties of the metal alloy used in the fabrication of the metamaterial l...

  3. Electronic structure and optical properties of a new type of semiconductor material:graphene monoxide

    Institute of Scientific and Technical Information of China (English)

    Yang Gui; Zhang Yufeng; Yan Xunwang

    2013-01-01

    The electronic and optical properties of graphene monoxide,a new type of semiconductor material,are theoretically studied by first-principles density functional theory.The calculated band structure shows that graphene monoxide is a semiconductor with a direct band gap of 0.95 eV.The density of states of graphene monoxide and the partial density of states for C and O are given to understand the electronic structure.In addition,we calculate the optical properties of graphene monoxide,including the complex dielectric function,absorption coefficient,complex refractive index,loss-function,reflectivity and conductivity.These results provide a physical basis for potential application in optoelectronic devices.

  4. Growth and applications of GeSn-related group-IV semiconductor materials

    Science.gov (United States)

    Zaima, Shigeaki; Nakatsuka, Osamu; Taoka, Noriyuki; Kurosawa, Masashi; Takeuchi, Wakana; Sakashita, Mitsuo

    2015-08-01

    We review the technology of Ge1-xSnx-related group-IV semiconductor materials for developing Si-based nanoelectronics. Ge1-xSnx-related materials provide novel engineering of the crystal growth, strain structure, and energy band alignment for realising various applications not only in electronics, but also in optoelectronics. We introduce our recent achievements in the crystal growth of Ge1-xSnx-related material thin films and the studies of the electronic properties of thin films, metals/Ge1-xSnx, and insulators/Ge1-xSnx interfaces. We also review recent studies related to the crystal growth, energy band engineering, and device applications of Ge1-xSnx-related materials, as well as the reported performances of electronic devices using Ge1-xSnx related materials.

  5. Hybrid bandgap engineering for super-hetero-epitaxial semiconductor materials, and products thereof

    Science.gov (United States)

    Park, Yeonjoon (Inventor); Choi, Sang H. (Inventor); King, Glen C. (Inventor); Elliott, James R. (Inventor)

    2012-01-01

    "Super-hetero-epitaxial" combinations comprise epitaxial growth of one material on a different material with different crystal structure. Compatible crystal structures may be identified using a "Tri-Unity" system. New bandgap engineering diagrams are provided for each class of combination, based on determination of hybrid lattice constants for the constituent materials in accordance with lattice-matching equations. Using known bandgap figures for previously tested materials, new materials with lattice constants that match desired substrates and have the desired bandgap properties may be formulated by reference to the diagrams and lattice matching equations. In one embodiment, this analysis makes it possible to formulate new super-hetero-epitaxial semiconductor systems, such as systems based on group IV alloys on c-plane LaF.sub.3; group IV alloys on c-plane langasite; Group III-V alloys on c-plane langasite; and group II-VI alloys on c-plane sapphire.

  6. Growth and applications of GeSn-related group-IV semiconductor materials.

    Science.gov (United States)

    Zaima, Shigeaki; Nakatsuka, Osamu; Taoka, Noriyuki; Kurosawa, Masashi; Takeuchi, Wakana; Sakashita, Mitsuo

    2015-08-01

    We review the technology of Ge1-x Sn x -related group-IV semiconductor materials for developing Si-based nanoelectronics. Ge1-x Sn x -related materials provide novel engineering of the crystal growth, strain structure, and energy band alignment for realising various applications not only in electronics, but also in optoelectronics. We introduce our recent achievements in the crystal growth of Ge1-x Sn x -related material thin films and the studies of the electronic properties of thin films, metals/Ge1-x Sn x , and insulators/Ge1-x Sn x interfaces. We also review recent studies related to the crystal growth, energy band engineering, and device applications of Ge1-x Sn x -related materials, as well as the reported performances of electronic devices using Ge1-x Sn x related materials.

  7. Functionalization of Organic Semiconductors and Other Carbon-based Materials by Self-Assembled Monolayers (SAMs) and Charge Transport in Organic Field-effect Transistors (OFETs)

    Science.gov (United States)

    Lee, Bumsu

    In the first part of the thesis, studies of the charge carrier transport in organic semiconductors performed using organic field-effect transistors (OFETs) with polymeric gate dielectric (parylene) are presented. By combining OFET and ultraviolet photoelectron spectroscopy (UPS) studies, the effect of bias-stress instability at the semiconductor/insulator interface have been investigated and understood. The effect is understood in terms of the transfer of holes from an accumulation channel of the semiconductor to localized states of the insulator that depends on energetic overlap between HOMO band tails of the semiconductor and the insulator. Second, surface functionalization of various materials such as organic single crystals, conjugated semiconductor polymers, graphene and carbon nanotubes (CNTs) with Self-Assembled Monolayers (SAMs) is described. In most cases, an enhanced surface conductivity is observed as a result of SAM treatment. Especially, fluorinated alkyl-silane (FTS) SAM induces the highest density of p-type charge carriers (in excess of an order of 1013cm-2), which leads to a strong surface hole-doping of these materials. In this thesis, (1) the mechanism of SAM nucleation, growth process and doping effect at the surface of organic single crystals and graphene is revealed. SAM nucleation occurs predominantly at molecular step edges or defect sites present at the surface and a consecutive lateral growth proceeds by cross-linking between SAM molecules. The strong hole-doping is explained by an interfacial charge transfer that during SAM formation. In addition, conductive atomic force microscopy (C-AFM) confirms that conducting paths along the step edges are formed by FTS nucleation at the early stage of FTS growth on rubrene. (2) it is reported that conductivity of solution-deposited thin film of conjugated polymers increases by up to six orders of magnitude, reaching (1.1 ± 0.1) × 103 Scm-1 for poly (2,5-bis(3-tetradecylthiophen-2-yl)thieno[3,2-b

  8. Methods for forming group III-V arsenide-nitride semiconductor materials

    Science.gov (United States)

    Major, Jo S. (Inventor); Welch, David F. (Inventor); Scifres, Donald R. (Inventor)

    2000-01-01

    Methods are disclosed for forming Group III--arsenide-nitride semiconductor materials. Group III elements are combined with group V elements, including at least nitrogen and arsenic, in concentrations chosen to lattice match commercially available crystalline substrates. Epitaxial growth of these III-V crystals results in direct bandgap materials, which can be used in applications such as light emitting diodes and lasers. Varying the concentrations of the elements in the III-V crystals varies the bandgaps, such that materials emitting light spanning the visible spectra, as well as mid-IR and near-UV emitters, can be created. Conversely, such material can be used to create devices that acquire light and convert the light to electricity, for applications such as full color photodetectors and solar energy collectors. The growth of the III-V crystals can be accomplished by growing thin layers of elements or compounds in sequences that result in the overall lattice match and bandgap desired.

  9. Structural semiconductor-to-semimetal phase transition in two-dimensional materials induced by electrostatic gating.

    Science.gov (United States)

    Li, Yao; Duerloo, Karel-Alexander N; Wauson, Kerry; Reed, Evan J

    2016-01-01

    Dynamic control of conductivity and optical properties via atomic structure changes is of technological importance in information storage. Energy consumption considerations provide a driving force towards employing thin materials in devices. Monolayer transition metal dichalcogenides are nearly atomically thin materials that can exist in multiple crystal structures, each with distinct electrical properties. By developing new density functional-based methods, we discover that electrostatic gating device configurations have the potential to drive structural semiconductor-to-semimetal phase transitions in some monolayer transition metal dichalcogenides. Here we show that the semiconductor-to-semimetal phase transition in monolayer MoTe2 can be driven by a gate voltage of several volts with appropriate choice of dielectric. We find that the transition gate voltage can be reduced arbitrarily by alloying, for example, for Mo(x)W(1-x)Te2 monolayers. Our findings identify a new physical mechanism, not existing in bulk materials, to dynamically control structural phase transitions in two-dimensional materials, enabling potential applications in phase-change electronic devices.

  10. Modification of semiconductor materials using laser-produced ion streams additionally accelerated in the electric fields

    Science.gov (United States)

    Rosinski, M.; Badziak, B.; Parys, P.; Wołowski, J.; Pisarek, M.

    2009-03-01

    The laser-produced ion stream may be attractive for direct ultra-low-energy ion implantation in thin layer of semiconductor for modification of electrical and optical properties of semiconductor devices. Application of electrostatic fields for acceleration and formation of laser-generated ion stream enables to control the ion stream parameters in broad energy and current density ranges. It also permits to remove the useless laser-produced ions from the ion stream designed for implantation. For acceleration of ions produced with the use of a low fluence repetitive laser system (Nd:glass: 2 Hz, pulse duration: 3.5 ns, pulse energy:˜0.5 J, power density: 10 10 W/cm 2) in IPPLM the special electrostatic system has been prepared. The laser-produced ions passing through the diaphragm (a ring-shaped slit in the HV box) have been accelerated in the system of electrodes. The accelerating voltage up to 40 kV, the distance of the diaphragm from the target, the diaphragm diameter and the gap width were changed for choosing the desired parameters (namely the energy band of the implanted ions) of the ion stream. The characteristics of laser-produced Ge ion streams were determined with the use of precise ion diagnostic methods, namely: electrostatic ion energy analyser and various ion collectors. The laser-produced and post-accelerated Ge ions have been used for implantation into semiconductor materials for nanocrystal fabrication. The characteristics of implanted samples were measured using AES.

  11. Semiconductor Nanocrystals Hybridized with Functional Ligands: New Composite Materials with Tunable Properties

    Directory of Open Access Journals (Sweden)

    Nathan I. Hammer

    2010-01-01

    Full Text Available Semiconductor nanocrystals hybridized with functional ligands represent an important new class of composite nanomaterials. The development of these new nanoscale building blocks has intensified over the past few years and offer significant advantages in a wide array of applications. Functional ligands allow for incorporation of nanocrystals into areas where their unique photophysics can be exploited. Energy and charge transfer between the ligands and the nanocrystal also result in enhanced physical properties that can be tuned by the choice of ligand architecture. Here, progress in the development and applications involving this new class of composite materials will be discussed.

  12. Dual-Material Surrounding-Gate Metal-Oxide-Semiconductor Field Effect Transistors with Asymmetric Halo

    Institute of Scientific and Technical Information of China (English)

    LI Zun-Chao

    2009-01-01

    Asymmetrical halo and dual-material gate structure are used in the sub-100 nm surrounding-gate metal-oxide-semiconductor field effect transistor (MOSFET) to improve the performance. Using three-region parabolic po-tential distribution and universal boundary condition, analytical surface potential and threshold voltage models of the novel MOSFET are developed based on the solution of Poisson's equation. The performance of the MOS-FET is examined by the analytical models and the 3D numerical device simulator Davinci. It is shown that the novel MOSFET can suppress short channel effect and improve carrier transport efficiency. The derived analytical models agree well with Davinci.

  13. First-principles study of p-type ZnO by S-Na co-doping

    Science.gov (United States)

    Tan, Xingyi; Li, Qiang; Zhu, Yongdan

    2017-08-01

    Using the first-principles method based on the density functional theory, the formation energy, electronic structures of S-Na co-doping in ZnO were calculated. The calculated results show that NaZn-SO have smaller formation energy than Nain-SO in energy ranges from -3.10 to 0 eV of {μ }{{O}}, indicating that it opens up a new opportunity for growth the p-type ZnO. The band structure shows that the NaZn system is a p-type direct-band-gap semiconductor material and the calculated band gap (0.84 eV) is larger than pure ZnO (0.74 eV). The NaZn-SO system is also a p-type semiconductor material with a direct band gap (0.80 eV). The influence of S-Na co-doping in ZnO on p-type conductivity is also discussed. The effective masses of NaZn-SO are larger than effective masses of NaZn and the NaZn-SO have more hole carriers than NaZn, meaning the hole in the NaZn-SO system may have a better carrier transfer character. So we inferred that NaZn-SO should be a candidate of p-type conduction. Project supported by the Natural Science Foundation of Hubei Province, China (Nos. 2014CFB342, 2014CFB619) and the Doctoral Foundation for Scientific Research of Hubei University for Nationalities (No. MY2013B020).

  14. Rashba semiconductor as spin Hall material: Experimental demonstration of spin pumping in wurtzite $n$-GaN:Si

    OpenAIRE

    2016-01-01

    Pure spin currents in semiconductors are essential for implementation in the next generation of spintronic elements. Heterostructures of III- nitride semiconductors are currently employed as central building-blocks for lighting and high-power devices. Moreover, the long relaxation times and the spin-orbit coupling (SOC) in these materials indicate them as privileged hosts for spin currents and related phenomena. Spin pumping is an efficient mechanism for the inception of spin current and its ...

  15. Spectrophotometric method for optical band gap and electronic transitions determination of semiconductor materials

    Science.gov (United States)

    Sangiorgi, Nicola; Aversa, Lucrezia; Tatti, Roberta; Verucchi, Roberto; Sanson, Alessandra

    2017-02-01

    The optical band gap energy and the electronic processes involved are important parameters of a semiconductor material and it is therefore important to determine their correct values. Among the possible methods, the spectrophotometric is one of the most common. Several methods can be applied to determine the optical band gap energy and still now a defined consensus on the most suitable one has not been established. A highly diffused and accurate optical method is based on Tauc relationship, however to apply this equation is necessary to know the nature of the electronic transitions involved commonly related to the coefficient n. For this purpose, a spectrophotometric technique was used and we developed a graphical method for electronic transitions and band gap energy determination for samples in powder form. In particular, the n coefficient of Tauc equation was determined thorough mathematical elaboration of experimental results on TiO2 (anatase), ZnO, and SnO2. The results were used to calculate the band gap energy values and then compared with the information obtained by Ultraviolet Photoelectron Spectroscopy (UPS). This approach provides a quick and accurate method for band gap determination through n coefficient calculation. Moreover, this simple but reliable method can be used to evaluate the nature of electronic transition that occurs in a semiconductor material in powder form.

  16. Synthesis and characterization of LiZnP and LiZnAs semiconductor material

    Science.gov (United States)

    Montag, Benjamin W.; Reichenberger, Michael A.; Arpin, Kevin R.; Sunder, Madhana; Nelson, Kyle A.; Ugorowski, Philip B.; McGregor, Douglas S.

    2015-02-01

    Research for a reliable solid-state semiconductor neutron detector continues because such a device has not been developed, and would have greater efficiency, than present-day gas-filled 3He and 10BF3 neutron detectors. Further, a semiconductor neutron detector would be more compact and rugged than most gas-filled or scintillator neutron detectors. The 6Li(n,t)4He reaction yields a total Q value of 4.78 MeV, a larger yield than the 10B(n,α)7Li, and is easily identified above background radiation interactions. Hence, devices composed of either natural Li (naturally 7.5% 6Li) or enriched 6Li (approximately 95% 6Li) may provide a semiconductor material for compact high-efficiency neutron detectors. A sub-branch of the III-V semiconductors, the filled tetrahedral compounds, known as Nowotny-Juza compounds (AIBIICV), are desirable for their cubic crystal structure and semiconducting electrical properties. These compounds were originally studied for photonic applications. In the present work, Equimolar portions of Li, Zn, and P or As were sealed under vacuum (10-6 Torr) in quartz ampoules with a boron nitride lining, and loaded into a compounding furnace. The ampoule was heated to 200 °C to form the Li-Zn alloy, subsequently heated to 560 °C to form the ternary compound, LiZnP or LiZnAs, and finally annealed to promote crystallization. The chemical composition of the synthesized starting material was confirmed at Galbraith Laboratories, Inc. by Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES), which showed the compounds can be reacted in equal ratios, 1-1-1, to form ternary compounds. Recent additions to the procedure have produced higher yields, and greater synthesis reliability. Synthesized powders were also characterized by x-ray diffraction, where lattice constants of 5.751±.001 Å and 5.939±.002 Å for LiZnP and LiZnAs, respectively, were determined.

  17. Quantum modeling of semiconductor gain materials and vertical-external-cavity surface-emitting laser systems

    Energy Technology Data Exchange (ETDEWEB)

    Bueckers, Christina; Kuehn, Eckhard; Schlichenmaier, Christoph; Koch, Stephan W. [Department of Physics and Material Sciences Center, Philipps-University Marburg (Germany); Imhof, Sebastian; Thraenhardt, Angela [Faculty of Natural Sciences, Chemnitz University of Technology, Chemnitz (Germany); Hader, Joerg; Moloney, Jerome V. [Nonlinear Control Strategies, Inc., Tucson, AZ (United States); College of Optical Sciences, University of Arizona, Tucson, AZ (United States); Rubel, Oleg [Thunder Bay Regional Research Institute, Thunder Bay, ON (Canada); Department of Physics, Lakehead University, Thunder Bay, ON (Canada); Zhang, Wei [Centre for Biophotonics, SIPBS, University of Strathclyde, Glasgow, Scotland (United Kingdom); Ackemann, Thorsten [SUPA and Department of Physics, University of Strathclyde, Glasgow, Scotland (United Kingdom)

    2010-04-15

    This article gives an overview of the microscopic theory used to quantitatively model a wide range of semiconductor laser gain materials. As a snapshot of the current state of research, applications to a variety of actual quantum-well systems are presented. Detailed theory-experiment comparisons are shown and it is analyzed how the theory can be used to extract poorly known material parameters. The intrinsic laser loss processes due to radiative and nonradiative Auger recombination are evaluated microscopically. The results are used for realistic simulations of vertical-external-cavity surface-emitting laser systems. To account for nonequilibrium effects, a simplified model is presented using pre-computed microscopic scattering and dephasing rates. Prominent deviations from quasi-equilibrium carrier distributions are obtained under strong in-well pumping conditions. (Abstract Copyright [2010], Wiley Periodicals, Inc.)

  18. Magnetism in alkali-metal-doped wurtzite semiconductor materials controlled by strain engineering

    Science.gov (United States)

    Guo, J. H.; Li, T. H.; Liu, L. Z.; Hu, F. R.

    2016-09-01

    The study of the magnetism and optical properties of semiconductor materials by defect engineering has attracted much attention because of their potential uses in spintronic and optoelectronic devices. In this paper, first-principle calculations discloses that cationic vacancy formation energy of the doped wurtzite materials can be sharply decreased due to alkali metal dopants and shows that their magnetic properties strongly depend on defect and doping concentration. This effect can be ascribed to the volume change induced by foreign elements doped into the host system and atomic population's difference. The symmetric deformation induced by biaxial strain can further regulate this behavior. Our results suggest that the formation of cationic vacancy can be tailored by strain engineering and dopants incorporation.

  19. Preparation of P-type Bi2Te3 based thermoelectric material by hot pressing%热压法制备P型Bi2Te3基温差电材料研究

    Institute of Scientific and Technical Information of China (English)

    葛晓丽; 杨文昭; 张丽丽

    2012-01-01

    In this article,with the p-type pseudo-binary thermoelectric material Bi2Te3-Sb2Te3 as the precursor,the samples were prepared with vacuum hot pressing technology,and their properties were measured before and after the hot pressing.The results indicate that the hot pressing samples have higher density and mechanical strength,which improves the phenomenon of splitting along the cleavage plane.Meanwhile,the hot pressing method changes the crystal structure and carrier concentration in the materials,which lead to the decrease of electric conductivity and the change of Seebeck coefficient,and then results in the decrease of thermal conductivity.For comprehensive consideration,the thermoelectric figure of merit of the hot pressing material is basically equivalent to that of zone-melting samples,but the mechanical properties of the former are much better than the later,which will provide a great advantage in practical application.%以P型赝二元Bi2Te3-Sb2Te3体系温差电材料区熔晶棒为前驱体,采用真空热压烧结法制备材料样品.测试热压前后材料样品性能,测试结果表明:热压样品较区熔材料具有更高的致密度和机械强度,改善了Bi2Te3基温差电材料易沿解理面发生劈裂的现象;同时,热压工艺促使了材料内部晶体结构和载流子浓度的变化,引起材料电导率的降低和塞贝克系数的改变,导致材料热导率显著降低.综合考虑材料各项性能参数,热压材料的热电优值基本与区熔材料相当,但前者的力学强度明显优于后者,在实际使用中将占有明显的优势.

  20. Modification of semiconductor materials using laser-produced ion streams additionally accelerated in the electric fields

    Energy Technology Data Exchange (ETDEWEB)

    Rosinski, M. [Institute of Plasma Physics and Laser Microfusion, P.O. Box 49, Hery Street 23, 00-908 Warsaw (Poland)], E-mail: rosinski@ifpilm.waw.pl; Badziak, B.; Parys, P.; Wolowski, J. [Institute of Plasma Physics and Laser Microfusion, P.O. Box 49, Hery Street 23, 00-908 Warsaw (Poland); Pisarek, M. [Warsaw University of Technology, Material Science and Engineering Faculty, Warsaw (Poland)

    2009-03-01

    The laser-produced ion stream may be attractive for direct ultra-low-energy ion implantation in thin layer of semiconductor for modification of electrical and optical properties of semiconductor devices. Application of electrostatic fields for acceleration and formation of laser-generated ion stream enables to control the ion stream parameters in broad energy and current density ranges. It also permits to remove the useless laser-produced ions from the ion stream designed for implantation. For acceleration of ions produced with the use of a low fluence repetitive laser system (Nd:glass: 2 Hz, pulse duration: 3.5 ns, pulse energy:{approx}0.5 J, power density: 10{sup 10} W/cm{sup 2}) in IPPLM the special electrostatic system has been prepared. The laser-produced ions passing through the diaphragm (a ring-shaped slit in the HV box) have been accelerated in the system of electrodes. The accelerating voltage up to 40 kV, the distance of the diaphragm from the target, the diaphragm diameter and the gap width were changed for choosing the desired parameters (namely the energy band of the implanted ions) of the ion stream. The characteristics of laser-produced Ge ion streams were determined with the use of precise ion diagnostic methods, namely: electrostatic ion energy analyser and various ion collectors. The laser-produced and post-accelerated Ge ions have been used for implantation into semiconductor materials for nanocrystal fabrication. The characteristics of implanted samples were measured using AES.

  1. Rare earth-doped materials with enhanced thermoelectric figure of merit

    Science.gov (United States)

    Venkatasubramanian, Rama; Cook, Bruce Allen; Levin, Evgenii M.; Harringa, Joel Lee

    2016-09-06

    A thermoelectric material and a thermoelectric converter using this material. The thermoelectric material has a first component including a semiconductor material and a second component including a rare earth material included in the first component to thereby increase a figure of merit of a composite of the semiconductor material and the rare earth material relative to a figure of merit of the semiconductor material. The thermoelectric converter has a p-type thermoelectric material and a n-type thermoelectric material. At least one of the p-type thermoelectric material and the n-type thermoelectric material includes a rare earth material in at least one of the p-type thermoelectric material or the n-type thermoelectric material.

  2. Composite THz materials using aligned metallic and semiconductor microwires, experiments and interpretation.

    Science.gov (United States)

    Mazhorova, Anna; Gu, Jian Feng; Dupuis, Alexandre; Peccianti, Marco; Tsuneyuki, Ozaki; Morandotti, Roberto; Minamide, Hiroaki; Tang, Ming; Wang, Yuye; Ito, Hiromasa; Skorobogatiy, Maksim

    2010-11-22

    We report fabrication method and THz characterization of composite films containing either aligned metallic (tin alloy) microwires or chalcogenide As2Se3 microwires. The microwire arrays are made by stack-and-draw fiber fabrication technique using multi-step co-drawing of low-melting-temperature metals or semiconductor glasses together with polymers. Fibers are then stacked together and pressed into composite films. Transmission through metamaterial films is studied in the whole THz range (0.1-20 THz) using a combination of FTIR and TDS. Metal containing metamaterials are found to have strong polarizing properties, while semiconductor containing materials are polarization independent and could have a designable high refractive index. Using the transfer matrix theory, we show how to retrieve the complex polarization dependent refractive index of the composite films. Finally, we study challenges in the fabrication of metamaterials with sub-micrometer metallic wires by repeated stack-and-draw process by comparing samples made using 2, 3 and 4 consecutive drawings. When using metallic alloys we observe phase separation effects and nano-grids formation on small metallic wires.

  3. Abatement kinetics of 30 sulfonylurea herbicide residues in water by photocatalytic treatment with semiconductor materials.

    Science.gov (United States)

    Fenoll, José; Sabater, Paula; Navarro, Ginés; Vela, Nuria; Pérez-Lucas, Gabriel; Navarro, Simón

    2013-11-30

    Sulfonylurea herbicides (SUHs) are a family of environmentally compatible herbicides but their high water solubility, moderate to high mobility through the soil profile, and slow degradation rate make them potential contaminants of groundwater as demonstrated in this paper. The photodegradation of a mixture of 30 SUHs in aqueous suspensions of semiconductor materials (ZnO and TiO2 in tandem with Na2S2O8 as electron acceptor) under artificial light (300-460 nm) irradiation was investigated. As expected, the influence of both semiconductors on the degradation of SUHs was very significant in all cases. Photocatalytic experiments show that the addition of photocatalyst, especially for the ZnO/Na2S2O8 system, greatly improves the removal of SUHs compared with photolytic tests, significantly increasing the reaction rates. The first-order equation (monophasic model) satisfactorily explained the disappearance process although it overlooked small residues remaining late in the process. These residues are important from an environmental point of view and the Hoerl function (biphasic model), was a better predicter of the results obtained. In our conditions, the average time required for 90% degradation was about 3 and 30 min for ZnO/Na2S2O8 and TiO2/Na2S2O8 systems, respectively.

  4. Material degradation of liquid organic semiconductors analyzed by nuclear magnetic resonance spectroscopy

    Directory of Open Access Journals (Sweden)

    Tatsuya Fukushima

    2015-08-01

    Full Text Available Liquid organic light-emitting diodes (liquid OLEDs are unique devices consisting only of liquid organic semiconductors in the active layer, and the device performances have been investigated recently. However, the device degradation, especially, the origin has been unknown. In this study, we show that material degradation occurs in liquid OLEDs, whose active layer is composed of carbazole with an ethylene glycol chain. Nuclear magnetic resonance (NMR experiments clearly exhibit that the dimerization reaction of carbazole moiety occurs in the liquid OLEDs during driving the devices. In contrast, cleavages of the ethylene glycol chain are not detected within experimental error. The dimerization reaction is considered to be related to the device degradation.

  5. Detection of fast neutrons from shielded nuclear materials using a semiconductor alpha detector.

    Science.gov (United States)

    Pöllänen, R; Siiskonen, T

    2014-08-01

    The response of a semiconductor alpha detector to fast (>1 MeV) neutrons was investigated by using measurements and simulations. A polyethylene converter was placed in front of the detector to register recoil protons generated by elastic collisions between neutrons and hydrogen nuclei of the converter. The developed prototype equipment was tested with shielded radiation sources. The low background of the detector and insensitivity to high-energy gamma rays above 1 MeV are advantages when the detection of neutron-emitting nuclear materials is of importance. In the case of a (252)Cf neutron spectrum, the intrinsic efficiency of fast neutron detection was determined to be 2.5×10(-4), whereas three-fold greater efficiency was obtained for a (241)AmBe neutron spectrum.

  6. Fast and high light yield scintillation in the Ga2O3 semiconductor material

    Science.gov (United States)

    Yanagida, Takayuki; Okada, Go; Kato, Takumi; Nakauchi, Daisuke; Yanagida, Satoko

    2016-04-01

    We report the distinct scintillation properties of the well-known Ga2O3 semiconductor material. Under UV excitation, the photoluminescence (PL) emission peak appeared near a wavelength of 380 nm with a quantum yield of 6%, and fast decays of 8 and 793 ns were observed. In contrast, the X-ray-induced scintillation spectrum showed an intense emission band near a wavelength of 380 nm, whose decay curve was reproduced using two exponential decay components with time constants of 8 and 977 ns. The pulse height spectrum of 137Cs γ-rays measured using Ga2O3 showed a clear photoabsorption peak with a light yield of 15000 ± 1500 photons/MeV.

  7. Universal solders for direct and powerful bonding on semiconductors, diamond, and optical materials

    Science.gov (United States)

    Mavoori, Hareesh; Ramirez, Ainissa G.; Jin, Sungho

    2001-05-01

    The surfaces of electronic and optical materials such as nitrides, carbides, oxides, sulfides, fluorides, selenides, diamond, silicon, and GaAs are known to be very difficult to bond with low melting point solders (<300 °C). We have achieved a direct and powerful bonding on these surfaces by using low temperature solders doped with rare-earth elements. The rare earth is stored in micron-scale, finely-dispersed intermetallic islands (Sn3Lu or Au4Lu), and when released, causes chemical reactions at the interface producing strong bonds. These solders directly bond to semiconductor surfaces and provide ohmic contacts. They can be useful for providing direct electrical contacts and interconnects in a variety of electronic assemblies, dimensionally stable and reliable bonding in optical fiber, laser, or thermal management assemblies.

  8. Diamond Structure BeO, Designable Super-Hard Materials and Semiconductor Be-Diamond

    Institute of Scientific and Technical Information of China (English)

    XU Ji-An; SI Yan; SUN Zong-Qi; XIE Hong-Sen

    2009-01-01

    It is possible for Beryllium oxide (BeO) to have a cubic diamond structure although it normally has a hexagonal structure under ambient conditions. As the solution of cubic BN and diamond, the solid solution of cubic BeO-diamond or BeO-cBN-diamond can potentially be a kind of super-hard materials with designable hardness; and this solution has also been confirmed based on our preliminary first principles calculations. In addition, the nonstoichiometry of BeO could create a mobile carrier in the cubic BeO-C or BeO-BN-C system and it might lead to a new type of semiconductor Be-diamond.

  9. A Novel Semiconductor CIGS Photovoltaic Material and Thin-Film ED Technology

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    In order to achieve low-cost high-efficiency thin-film solar cells, a novel Semiconductor Photovoltaic (PV) active material CuIn1-xGaxSe2 (CIGS) and thin-film Electro-Deposition (ED) technology is explored. Firstly,the PV materials and technologies is investigated, then the detailed experimental processes of CIGS/Mo/glass structure by using the novel ED technology and the results are reported. These results shows that high quality CIGS polycrystalline thin-films can be obtained by the ED method, in which the polycrystalline CIGS is definitely identified by the (112), (204, 220) characteristic peaks of the tetragonal structure, the continuous CIGS thin-film layers with particle average size of about 2μm of length and around 1.6μm of thickness. The thickness and solargrade quality of CIGS thin-films can be produced with good repeatability. Discussion and analysis on the ED technique, CIGS energy band and sodium (Na) impurity properties, were also performed. The alloy CIGS exhibits not only increasing band-gap with increasing x, but also a change in material properties that is relevant to the device operation. The beneficial impurity Na originating from the low-cost soda-lime glass substrate becomes one prerequisite for high quality CIGS films. These novel material and technology are very useful for low-cost high-efficiency thin-film solar cells and other devices.

  10. Piezoresistance in p-type silicon revisited

    DEFF Research Database (Denmark)

    Richter, Jacob; Pedersen, Jesper; Brandbyge, Mads;

    2008-01-01

    We calculate the shear piezocoefficient pi44 in p-type Si with a 6×6 k·p Hamiltonian model using the Boltzmann transport equation in the relaxation-time approximation. Furthermore, we fabricate and characterize p-type silicon piezoresistors embedded in a (001) silicon substrate. We find that the ...

  11. Comprehensive Characterization of Extended Defects in Semiconductor Materials by a Scanning Electron Microscope.

    Science.gov (United States)

    Hieckmann, Ellen; Nacke, Markus; Allardt, Matthias; Bodrov, Yury; Chekhonin, Paul; Skrotzki, Werner; Weber, Jörg

    2016-01-01

    Extended defects such as dislocations and grain boundaries have a strong influence on the performance of microelectronic devices and on other applications of semiconductor materials. However, it is still under debate how the defect structure determines the band structure, and therefore, the recombination behavior of electron-hole pairs responsible for the optical and electrical properties of the extended defects. The present paper is a survey of procedures for the spatially resolved investigation of structural and of physical properties of extended defects in semiconductor materials with a scanning electron microscope (SEM). Representative examples are given for crystalline silicon. The luminescence behavior of extended defects can be investigated by cathodoluminescence (CL) measurements. They are particularly valuable because spectrally and spatially resolved information can be obtained simultaneously. For silicon, with an indirect electronic band structure, CL measurements should be carried out at low temperatures down to 5 K due to the low fraction of radiative recombination processes in comparison to non-radiative transitions at room temperature. For the study of the electrical properties of extended defects, the electron beam induced current (EBIC) technique can be applied. The EBIC image reflects the local distribution of defects due to the increased charge-carrier recombination in their vicinity. The procedure for EBIC investigations is described for measurements at room temperature and at low temperatures. Internal strain fields arising from extended defects can be determined quantitatively by cross-correlation electron backscatter diffraction (ccEBSD). This method is challenging because of the necessary preparation of the sample surface and because of the quality of the diffraction patterns which are recorded during the mapping of the sample. The spatial resolution of the three experimental techniques is compared.

  12. Plasmon resonances in semiconductor materials for detecting photocatalysis at the single-particle level.

    Science.gov (United States)

    Yan, Jiahao; Lin, Zhaoyong; Ma, Churong; Zheng, Zhaoqiang; Liu, Pu; Yang, Guowei

    2016-08-11

    Hot carriers, generated via the non-radiative decay of localized surface plasmon, can be utilized in photovoltaic and photocatalytic devices. In recent years, most studies have focused on conventional plasmon materials like Au and Ag. However, they suffer from several drawbacks like low energy of the generated hot carriers and a high charge-carrier recombination rate. To resolve these problems, here, we propose the plasmon resonances in heavily self-doped titanium oxide (TiO1.67) to realize effective hot carrier generation. Since the plasmon resonant energy of TiO1.67 nanoparticles (2.56 eV) is larger than the bandgap (2.15 eV), plasmon resonances through interband transition can realize both the generation and separation of hot carriers and bring a new strategy for visible-light photodegradation. The photodegradation rate for methyl orange was about 0.034 min(-1). More importantly, the combination of plasmonic and catalytic properties makes it feasible to investigate the degradation process of different materials and different structures at the single particle level in situ. By detecting the scattering shift, we demonstrated that the TiO1.67 dimer (Δλ/ΔλRIU = 0.16) possesses a higher photodegradation rate than an individual nanoparticle (Δλ/ΔλRIU = 0.09). We hope this finding may be a beginning, paving the way toward the development of semiconductor plasmonic materials for new applications beyond noble metals.

  13. Inkjet-Printed Organic Field-Effect Transistor by Using Composite Semiconductor Material of Carbon Nanoparticles and Poly(3-Hexylthiophene

    Directory of Open Access Journals (Sweden)

    Chih-Ting Lin

    2011-01-01

    Full Text Available Poly(3-hexylthiophene, P3HT, has been widely used in organic electronics as a semiconductor material. It suffers from the low carrier mobility characteristics. This limits P3HT to be employed in applications. Therefore, the blending semiconductor material, carbon nanoparticle (CNP, and P3HT, are developed and examined by inkjet-printing organic field-effect transistor technology in this work. The effective carrier mobility of fabricated OFETs can be enhanced by 8 folds with adding CNP and using O2 plasma treatment. At the same time, the transconductance of fabricated OFETs is also raised by 5 folds. Based on the observations of SEM, XRD, and FTIR, these improvements are contributed to the local field induced by the formation of CNP/P3HT complexes. This observation presents an insight of the development in organic semiconductor materials. Moreover, this work also offers a low-cost and effective semiconductor material for inkjet-printing technology in the development of organic electronics.

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

    Science.gov (United States)

    Okojie, Robert S. (Inventor)

    2013-01-01

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

  15. New Organic Semiconductor Materials Applied in Organic Photovoltaic and Optical Devices

    Directory of Open Access Journals (Sweden)

    Andre F. S. Guedes

    2015-04-01

    Full Text Available The development of flexible organic photovoltaic solar cells, using an optically transparent substrate material and organic semiconductor materials, has been widely utilized by the electronic industry when producing new technological products. The flexible organic photovoltaic solar cells are the base Poly (3,4-ethylenedioxythiophene, PEDOT, Poly(3-hexyl thiophene, P3HT, Phenyl-C61-butyric acid methyl ester, PCBM and Polyaniline, PANI, were deposited in Indium Tin Oxide, ITO, and characterized by Electrical Measurements and Scanning Electron Microscopy (SEM. In addition, the thin film obtained by the deposition of PANI, prepared in perchloric acid solution, was identified through PANI-X1. The result obtained by electrical Measurements has demonstrated that the PET/ITO/PEDOT/P3HT:PCBM Blend/PANI-X1 layer presents the characteristic curve of standard solar cell after spin-coating and electrodeposition. The Thin film obtained by electrodeposition of PANI-X1 on P3HT/PCBM Blend was prepared in perchloric acid solution. These flexible organic photovoltaic solar cells presented power conversion efficiency of 12%. The inclusion of the PANI-X1 layer reduced the effects of degradation these organic photovoltaic panels induced for solar irradiation. In Scanning Electron Microscopy (SEM these studies reveal that the surface of PANI-X1 layers is strongly conditioned by the surface morphology of the dielectric.

  16. The Preemptive Stocker Dispatching Rule of Automatic Material Handling System in 300 mm Semiconductor Manufacturing Factories

    Science.gov (United States)

    Wang, C. N.; Lin, H. S.; Hsu, H. P.; Wang, Yen-Hui; Chang, Y. P.

    2016-04-01

    The integrated circuit (IC) manufacturing industry is one of the biggest output industries in this century. The 300mm wafer fabs is the major fab size of this industry. The automatic material handling system (AMHS) has become one of the most concerned issues among semiconductor manufacturers. The major lot delivery of 300mm fabs is used overhead hoist transport (OHT). The traffic jams are happened frequently due to the wide variety of products and big amount of OHTs moving in the fabs. The purpose of this study is to enhance the delivery performance of automatic material handling and reduce the delay and waiting time of product transportation for both hot lots and normal lots. Therefore, this study proposes an effective OHT dispatching rule: preemptive stocker dispatching (PSD). Simulation experiments are conducted and one of the best differentiated preemptive rule, differentiated preemptive dispatching (DPD), is used for comparison. Compared with DPD, The results indicated that PSD rule can reduce average variable delivery time of normal lots by 13.15%, decreasing average variable delivery time of hot lots by 17.67%. Thus, the PSD rule can effectively reduce the delivery time and enhance productivity in 300 mm wafer fabs.

  17. X-ray photoemission electron microscopy for the study of semiconductor materials

    Energy Technology Data Exchange (ETDEWEB)

    Anders, S.; Stammler, T.; Padmore, H.A. [Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94720 (United States); Terminello, L.J.; Jankowski, A.F. [Lawrence Livermore National Laboratory, 7000 East Ave., Livermore, California 94550 (United States); Stoehr, J. [IBM Almaden Research Center, 650 Harry Road, San Jose, California 95120 (United States); Diaz, J. [Departamento de Fisic, Facultad de Ciencias, Universidad de Oviedo, Avda. Calvo Sotelo s/n, Oviedo, 33007 (Spain); Cossy-Favre, A. [EMPA, Duebendorf, Ueberlandstrasse 129, 8600 Duebendorf (Switzerland); Singh, S. [Center for X-ray Lithography, University of Wisconsin-Madison, Stoughton, Wisconsin 53589 (United States)

    1998-11-01

    Photoemission Electron Microscopy using X-rays (X-PEEM) is a novel combination of two established materials analysis techniques{emdash}PEEM using UV light, and Near Edge X-ray Absorption Fine Structure (NEXAFS) spectroscopy. This combination allows the study of elemental composition and bonding structure of the sample by NEXAFS spectroscopy with a high spatial resolution given by the microscope. A simple, two lens, 10 kV operation voltage PEEM has been used at the Stanford Synchrotron Radiation Laboratory and at the Advanced Light Source (ALS) in Berkeley to study various problems including materials of interest for the semiconductor industry. In the present paper we give a short overview over the method and the instrument which was used, and describe in detail a number of applications. These applications include the study of the different phases of titanium disilicide, various phases of boron nitride, and the analysis of small particles. A brief outlook is given on possible new fields of application of the PEEM technique, and the development of new PEEM instruments. {copyright} {ital 1998 American Institute of Physics.}

  18. X-ray photoemission electron microscopy for the study of semiconductor materials

    Energy Technology Data Exchange (ETDEWEB)

    Anders, S.; Stammler, T.; Padmore, H. [Lawrence Berkeley National Lab., CA (United States). Advanced Light Source Div.; Terminello, L.J.; Jankowski, A.F. [Lawrence Livermore National Lab., CA (United States); Stohr, J. [IBM Almaden Research Center, San Jose, CA (United States); Diaz, J. [Univ. de Oviedo (Spain). Dept. de Fisica; Cossy-Gantner, A. [EMPA, Duebendorf (Germany)

    1998-03-01

    Photoemission Electron Microscopy (PEEM) using X-rays is a novel combination of two established materials analysis techniques--PEEM using UV light, and Near Edge X-ray Absorption Fine Structure (NEXAFS) spectroscopy. This combination allows the study of elemental composition and bonding structure of the sample by NEXAFS spectroscopy with a high spatial resolution given by the microscope. A simple, two lens, 10 kV operation voltage PEEM has been used at the Stanford Synchrotron Radiation Laboratory and at the Advanced Light Source (ALS) in Berkeley to study various problems including materials of interest for the semiconductor industry. In the present paper the authors give a short overview over the method and the instrument which was used, and describe in detail a number of applications. These applications include the study of the different phases of titanium disilicide, various phases of boron nitride, and the analysis of small particles. A brief outlook is given on possible new fields of application of the PEEM technique, and the development of new PEEM instruments.

  19. Transparent Oxide Semiconductors for Emerging Electronics

    KAUST Repository

    Caraveo-Frescas, Jesus Alfonso

    2013-11-01

    Transparent oxide electronics have emerged as promising materials to shape the future of electronics. While several n-type oxides have been already studied and demonstrated feasibility to be used as active materials in thin film transistors, high performance p-type oxides have remained elusive. This dissertation is devoted to the study of transparent p-type oxide semiconductor tin monoxide and its use in the fabrication of field effect devices. A complete study on the deposition of tin monoxide thin films by direct current reactive magnetron sputtering is performed. Carrier density, carrier mobility and conductivity are studied over a set of deposition conditions where p-type conduction is observed. Density functional theory simulations are performed in order to elucidate the effect of native defects on carrier mobility. The findings on the electrical properties of SnO thin films are then translated to the fabrication of thin films transistors. The low processing temperature of tin monoxide thin films below 200 oC is shown advantageous for the fabrication of fully transparent and flexible thin film transistors. After careful device engineering, including post deposition annealing temperature, gate dielectric material, semiconductor thickness and source and drain electrodes material, thin film transistors with record device performance are demonstrated, achieving a field effect mobility >6.7 cm2V-1s-1. Device performance is further improved to reach a field effect mobility of 10.8 cm2V-1s-1 in SnO nanowire field effect transistors fabricated from the sputtered SnO thin films and patterned by electron beam lithography. Downscaling device dimension to nano scale is shown beneficial for SnO field effect devices not only by achieving a higher hole mobility but enhancing the overall device performance including better threshold voltage, subthreshold swing and lower number of interfacial defects. Use of p-type semiconductors in nonvolatile memory applications is then

  20. Improve sonocatalytic performance using modified semiconductor catalyst SnO2 and ZrO2 by magnetite materials

    Science.gov (United States)

    Paramarta, V.; Kristianto, Y.; Taufik, A.; Saleh, R.

    2017-04-01

    Modifying semiconductor catalysts using magnetic materials could enhance the efficiency of wastewater removal and the separation efficiency demonstrated in our previous studies. The catalytic performance of wide band gap ZrO2 and SnO2 semiconductors has not been studied with regard to the ultrasonic radiation catalytic process. Therefore, the ultrasound-assisted sonocatalytic performance of ZrO2 and SnO2 semiconductors combined with Fe3O4 (magnetite) nanoparticles has been studied using methylene blue as a model organic pollutant. The nanocomposites were synthesized using sol-gel methods. The structural properties of the samples were characterized using X-ray diffraction (XRD). Sample morphology was obtained by transmission electron microscopy (TEM). The magnetic properties of the samples were characterized using a vibrating sample magnetometer (VSM). The cubic spinel structure of Fe3O4 is successfully identified, as are the tetragonal structures from SnO2 and ZrO2. The samples exhibit ferromagnetic behavior at room temperature. Both ZrO2 and SnO2 combined with Fe3O4 show better sonocatalytic efficiency than without Fe3O4 and even better efficiency than the pioneering wide band gap semiconductor TiO2. The combination of magnetite nanoparticles with SnO2 exhibit the highest degradation efficiency. The incorporation of magnetic material into catalysts has been proved to enhance the reusability of catalysts with efficient separation process.

  1. Applications of ions produced by low intensity repetitive laser pulses for implantation into semiconductor materials

    Science.gov (United States)

    Wołowski, J.; Badziak, J.; Czarnecka, A.; Parys, P.; Pisarek, M.; Rosinski, M.; Turan, R.; Yerci, S.

    This work reports experiment concerning specific applications of implantation of laser-produced ions for production of semiconductor nanocrystals. The investigation was carried out in the IPPLM within the EC STREP `SEMINANO' project. A repetitive pulse laser system of parameters: energy up to 0.8 J in a 3.5 ns-pulse, wavelength of 1.06 μ m, repetition rate of up to 10 Hz, has been employed in these investigations. The characterisation of laser-produced ions was performed with the use of `time-of-flight' ion diagnostics simultaneously with other diagnostic methods in dependence on laser pulse parameters, illumination geometry and target material. The properties of laser-implanted and modified SiO2 layers on sample surface were characterised with the use of different methods (XPS + ASD, Raman spectroscopy, PL spectroscopy) at the Middle East Technological University in Ankara and at the Warsaw University of Technology. The production of the Ge nanocrystallites has been demonstrated for annealed samples prepared in different experimental conditions.

  2. Alpha-particle emissivity screening of materials used for semiconductor manufacturing

    Science.gov (United States)

    Gordon, Michael; Rodbell, Kenneth

    2015-03-01

    Single-Event Upsets (SEU's) in semiconductor memory and logic devices continue to be a reliability issue in modern CMOS devices. SEU's result from deposited charge in the Si devices caused by the passage of ionizing radiation. With technology scaling, the device area decreases, but the critical charge required to flip bits decreases as well. The interplay between both determines how the SEU rate scales with shrinking device geometries and dimensions. In order to minimize the alpha-particle component of SEU, the radiation in the device environment has to be at the Ultra-Low Alpha (ULA) activity levels, e.g. less than 2 α/khr-cm2. Most detectors have background levels that are significantly larger than that level which makes making these measurements difficult and time consuming. A new class of alpha particle detector, utilizing pulse shape discrimination, is now available which allows one to make measurements quickly with ultra-low detector background. This talk will discuss what is involved in making alpha particle measurements of materials in the ULA activity levels, in terms of calibration, radon adsorption mitigation, the time required for obtaining reasonable statistics and comparisons to other detectors.

  3. Large area growth and electrical properties of p-type WSe2 atomic layers.

    Science.gov (United States)

    Zhou, Hailong; Wang, Chen; Shaw, Jonathan C; Cheng, Rui; Chen, Yu; Huang, Xiaoqing; Liu, Yuan; Weiss, Nathan O; Lin, Zhaoyang; Huang, Yu; Duan, Xiangfeng

    2015-01-14

    Transition metal dichacogenides represent a unique class of two-dimensional layered materials that can be exfoliated into single or few atomic layers. Tungsten diselenide (WSe(2)) is one typical example with p-type semiconductor characteristics. Bulk WSe(2) has an indirect band gap (∼ 1.2 eV), which transits into a direct band gap (∼ 1.65 eV) in monolayers. Monolayer WSe(2), therefore, is of considerable interest as a new electronic material for functional electronics and optoelectronics. However, the controllable synthesis of large-area WSe(2) atomic layers remains a challenge. The studies on WSe(2) are largely limited by relatively small lateral size of exfoliated flakes and poor yield, which has significantly restricted the large-scale applications of the WSe(2) atomic layers. Here, we report a systematic study of chemical vapor deposition approach for large area growth of atomically thin WSe(2) film with the lateral dimensions up to ∼ 1 cm(2). Microphotoluminescence mapping indicates distinct layer dependent efficiency. The monolayer area exhibits much stronger light emission than bilayer or multilayers, consistent with the expected transition to direct band gap in the monolayer limit. The transmission electron microscopy studies demonstrate excellent crystalline quality of the atomically thin WSe(2). Electrical transport studies further show that the p-type WSe(2) field-effect transistors exhibit excellent electronic characteristics with effective hole carrier mobility up to 100 cm(2) V(-1) s(-1) for monolayer and up to 350 cm(2) V(-1) s(-1) for few-layer materials at room temperature, comparable or well above that of previously reported mobility values for the synthetic WSe(2) and comparable to the best exfoliated materials.

  4. Composite THz materials using aligned metallic and semiconductor microwires, experiments and interpretation

    National Research Council Canada - National Science Library

    Mazhorova, Anna; Gu, Jian Feng; Dupuis, Alexandre; Peccianti, Marco; Tsuneyuki, Ozaki; Morandotti, Roberto; Minamide, Hiroaki; Tang, Ming; Wang, Yuye; Ito, Hiromasa; Skorobogatiy, Maksim

    2010-01-01

    ...) microwires or chalcogenide As2Se3 microwires. The microwire arrays are made by stack-and-draw fiber fabrication technique using multi-step co-drawing of low-melting-temperature metals or semiconductor glasses together with polymers...

  5. Space processing of crystalline materials: A study of known methods of electrical characterization of semiconductors: Bibliography

    Science.gov (United States)

    Castle, J. G.

    1976-01-01

    A selective bibliography is given on electrical characterization techniques for semiconductors. Emphasis is placed on noncontacting techniques for the standard electrical parameters for monitoring crystal growth in space, preferably in real time with high resolution.

  6. Evolution of plant P-type ATPases

    Directory of Open Access Journals (Sweden)

    Christian N.S. Pedersen

    2012-02-01

    Full Text Available Five organisms having completely sequenced genomes and belonging to all major branches of green plants (Viridiplantae were analyzed with respect to their content of P-type ATPases encoding genes. These were the chlorophytes Ostreococcus tauria and Chlamydomonas reinhardtii, and the streptophytes Physcomitrella patens (a moss, Selaginella moellendorffii (a primitive vascular plant, and Arabidopsis thaliana (a model flowering plant. Each organism contained sequences for all five subfamilies of P-type ATPases. Our analysis demonstrates when specific subgroups of P-type ATPases disappeared in the evolution of Angiosperms. Na/K-pump related P2C ATPases were lost with the evolution of streptophytes whereas Na+ or K+ pumping P2D ATPases and secretory pathway Ca2+-ATPases remained until mosses. An N-terminally located calmodulin binding domain in P2B ATPases can only be detected in pumps from Streptophytae, whereas, like in animals, a C-terminally localized calmodulin binding domain might be present in chlorophyte P2B Ca2+-ATPases. Chlorophyte genomes encode P3A ATPases resembling protist plasma membrane H+-ATPases and a C-terminal regulatory domain is missing. The complete inventory of P-type ATPases in the major branches of Viridiplantae is an important starting point for elucidating the evolution in plants of these important pumps.

  7. Method of ions acceleration for laser-induced implantation of semiconductor materials

    Science.gov (United States)

    Czarnecka, A.; Badziak, J.; Parys, P.; Rosinski, M.; Wołowski, J.

    The application of electrostatic fields for the formation of laser-generated ions makes it possible to control the ion stream parameters in broad energy and current density ranges. It also permits to remove the useless ions from the ion stream designed for laser-induced implantation and deposition of layers of semiconductor materials. For acceleration of ions a special electrostatic system has been completed and tested at the Institute of Plasma Physics and Laser Microfusion (IPPLM). A repetitive Nd: glass laser with energy of ˜0.5 J in a 3.5 ns pulse, wavelength of 1.06 μm, repetition rate of up to 10 Hz and intensity on the target of up to 1011 W cm-2, has been recently employed to produce ions emitted from irradiated solid targets. The movable target holder was located inside the cylindrical box connected with a high-voltage source (up to 50 kV). The ions passing through the diaphragm in this box were accelerated in the system of electrodes in the electrostatic field formed in the gap between the box and a grid mounted at the end of the grounded cylindrical electrode. The parameters of the ion streams were measured with the use of several ion collectors and an electrostatic ion energy analyzer (IEA). The Ge ion stream attained energy of up to 30 keV and ion fluency 1011 ions/cm2 for one laser shot. The maximum ion charge state measured with the use of IEA was 3+.

  8. Full-band structure modeling of the radiative and non-radiative properties of semiconductor materials and devices (Presentation Recording)

    Science.gov (United States)

    Bellotti, Enrico; Wen, Hanqing; Pinkie, Benjamin; Matsubara, Masahiko; Bertazzi, Francesco

    2015-08-01

    Understanding the radiative and non-radiative properties of semiconductor materials is a prerequisite for optimizing the performance of existing light emitters and detectors and for developing new device architectures based on novel materials. Due to the ever increasing complexity of novel semiconductor systems and their relative technological immaturity, it is essential to have design tools and simulation strategies that include the details of the microscopic physics and their dependence on the macroscopic (continuum) variables in the macroscopic device models. Towards this end, we have developed a robust full-band structure based approach that can be used to study the intrinsic material radiative and non-radiative properties and evaluate the same characteristics of low-dimensional device structures. A parallel effort is being carried out to model the effect of substrate driven stress/strain and material quality (dislocations and defects) on microscopic quantities such as non-radiative recombination rate. Using this modeling approach, we have extensively studied the radiative and non-radiative properties of both elemental (Si and Ge) and compound semiconductors (HgCdTe, InGaAs, InAsSb and InGaN). In this work we outline the details of the modelling approach, specifically the challenges and advantages related to the use of the full-band description of the material electronic structure. We will present a detailed comparison of the radiative and Auger recombination rates as a function of temperature and doping for HgCdTe and InAsSb that are two important materials for infrared detectors and emitters. Furthermore we will discuss the role of non-radiatiave Auger recombination processes in explaining the performance of light emitter diodes. Finally we will present the extension of the model to low dimensional structures employed in a number of light emitter and detector structures.

  9. Synthesis and characterization of polymer matrix composite material with combination of ZnO filler and nata de coco fiber as a candidate of semiconductor material

    Science.gov (United States)

    Saputra, Asep Handaya; Anindita, Hana Nabila

    2015-12-01

    Synthesis of semiconductor composite using acrylic matrix filled with ZnO and nata de coco fiber has been conducted in this research. The purpose of this research is to obtain semiconductor composite material that has a good mechanical strength and thermal resistance. In situ polymerization method is used in this research and the composites are ready to be characterized after 12 hours. The main parameter that is characterized is the electric conductivity of the composite. Additional parameters are also characterized such as composite's elastic modulus and glass transition temperature. The composites that has been made in this research can be classified as semiconductor material because the conductivity is in the range of 10-8-103 S/cm. In general the addition of ZnO and nata de coco filler can increase the conductivity of the composite. The highest semiconductor characteristic in acrylic/ZnO composite is obtained from 30% volume filler that reach 3.4 x 10-7 S/cm. Similar with acrylic/ZnO composite, in acrylic/nata de coco fiber composite the highest semiconductor characteristic is also obtained from 30% volume filler that reach 1.15 x 10-7 S/cm. Combination of 20% volume of ZnO, 10% volume of nata de coco, and 70% volume of acrylic resulting in composite with electric conductivity of 1.92 x 10-7 S/cm. In addition, combination of ZnO and nata de coco fiber as filler in composite can also improve the characteristic of composite where composite with 20% volume of ZnO filler and 10% volume of nata de coco fiber resulting in composite with elastic modulus of 1.79 GPa and glass transition temperature of 175.73°C which is higher than those in acrylic/ZnO composite.

  10. 2014 Defects in Semiconductors Gordon Research Conference & Gordon Research Seminar. Research Area 1: Materials Science, 1.3 Physical Properties of Materials

    Science.gov (United States)

    2014-08-01

    graphene -like layered materials, novel photovoltaic materials, organic semiconductors and the likes in bulk, film, or nanostructured forms. We anticipate to...Pat Lenahan (Penn State University) "Interface Defects in SiO2 /SiC by Spin Resonance" 9:20 pm - 9:30 pm Discussion 9:30 pm Poster Session I... Graphene and Like Materials 7:30 pm - 7:50 pm Discussion Leader: Humberto Terrones (Rensselaer) "Introduction" 7:50 pm - 8:25 pm Mildred

  11. Applications of Secondary Electron Composition Contrast Imaging Method in Microstructure Studies on Heterojunction Semiconductor Devices and Multilayer Materials

    Institute of Scientific and Technical Information of China (English)

    1999-01-01

    The principle, imaging condition and experimental method for obtaining high resolution composition contrast in secondary electron image were described. A new technique of specimen preparation for secondary electron composition contrast observation was introduced and discussed. By using multilayer P+-Si1-xGex/p-Si heterojunction internal photoemission infrared detector as an example, the applications of secondary electron composition contrast imaging in microstructure studies on heterojunction semiconducting materials and devices were stated. The characteristics of the image were compared with the ordinary transmission electron diffraction contrast image. The prospects of applications of the imaging method in heterojunction semiconductor devices and multilayer materials are also discussed.

  12. Visible Light Enabled Photocatalytic Splitting of Water over Spatially Isolated Semiconductors Supported Mesoporous Materials

    Science.gov (United States)

    Peng, Rui

    Hydrogen generation from photocatalytic splitting of water is an ideal scenario that possesses promise for the sustainable development of human society and the establishment of the ultimate "green," infinitely renewable energy system. This work contains a series of novel photocatalytic systems in which the photoactive chromophores and/or the co-catalysts were incorporated into highly periodically cubic-phased MCM-48 mesoporous materials to achieve significantly higher photocatalytic efficiencies compared with conventional semiconductor photocatalysts. Cubic-phased MCM-48 mesoporous materials were chosen as supports to accommodate the photoactive species throughout the entire work. Several unique and iconic properties of these materials, such as large surface area, highly uniform mesoscale pores arrayed in a long-range periodicity, and an interconnected network of three-dimensional sets of pores that were recognized as positive parameters facilitated the photogenerated charge transfer and promoted the photocatalytic performance of the encapsulated photoactive species. It was validated that in the CdS/TiO2-incorporated MCM-48 photocatalytic system, the solar hydrogen conversion efficiency was prevalently governed by the photogenerated electron injection efficiency from the CdS conduction band to that of TiO2. The use of MCM-48 mesoporous host materials enabled the high and even dispersion of both CdS and TiO 2 so that the intimate and sufficient contact between CdS and TiO 2 was realized. In addition, with the presence of both TiO2 and MCM-48 mesoporous support, the photostability of CdS species was dramatically enhanced compared with that of bare CdS or CdS-incorporated MCM-48 photocatalysts. In advance, by loading the RuO2 co-catalyst into the CdS/TiO 2-incorporated MCM-48 photocatalytic system, the photocatalytic splitting of pure water to generate both hydrogen and oxygen under visible light illumination was achieved. In the various Pd-assisted, TiO2-incorporated

  13. Assembling non-ferromagnetic materials to ferromagnetic architectures using metal-semiconductor interfaces

    Science.gov (United States)

    Ma, Ji; Liu, Chunting; Chen, Kezheng

    2016-01-01

    In this work, a facile and versatile solution route was used to fabricate room-temperature ferromagnetic fish bone-like, pteridophyte-like, poplar flower-like, cotton-like Cu@Cu2O architectures and golfball-like Cu@ZnO architecture. The ferromagnetic origins in these architectures were found to be around metal-semiconductor interfaces and defects, and the root cause for their ferromagnetism lay in charge transfer processes from metal Cu to semiconductors Cu2O and ZnO. Owing to different metallization at their interfaces, these architectures exhibited different ferromagnetic behaviors, including coercivity, saturation magnetization as well as magnetic interactions. PMID:27680286

  14. Space processing of crystalline materials: A study of known methods of electrical characterization of semiconductors

    Science.gov (United States)

    Castle, J. G.

    1976-01-01

    A literature survey is presented covering nondestructive methods of electrical characterization of semiconductors. A synopsis of each technique deals with the applicability of the techniques to various device parameters and to potential in-flight use before, during, and after growth experiments on space flights. It is concluded that the very recent surge in the commercial production of large scale integrated circuitry and other semiconductor arrays requiring uniformity on the scale of a few microns, involves nondestructive test procedures which could well be useful to NASA for in-flight use in space processing.

  15. Implications of the Differential Toxicological Effects of III-V Ionic and Particulate Materials for Hazard Assessment of Semiconductor Slurries.

    Science.gov (United States)

    Jiang, Wen; Lin, Sijie; Chang, Chong Hyun; Ji, Zhaoxia; Sun, Bingbing; Wang, Xiang; Li, Ruibin; Pon, Nanetta; Xia, Tian; Nel, André E

    2015-12-22

    Because of tunable band gaps, high carrier mobility, and low-energy consumption rates, III-V materials are attractive for use in semiconductor wafers. However, these wafers require chemical mechanical planarization (CMP) for polishing, which leads to the generation of large quantities of hazardous waste including particulate and ionic III-V debris. Although the toxic effects of micron-sized III-V materials have been studied in vivo, no comprehensive assessment has been undertaken to elucidate the hazardous effects of submicron particulates and released III-V ionic components. Since III-V materials may contribute disproportionately to the hazard of CMP slurries, we obtained GaP, InP, GaAs, and InAs as micron- (0.2-3 μm) and nanoscale (materials that could appear in slurries. This finding is of importance for considering how to deal with the hazard potential of CMP slurries.

  16. Oxide semiconductors

    CERN Document Server

    Svensson, Bengt G; Jagadish, Chennupati

    2013-01-01

    Semiconductors and Semimetals has distinguished itself through the careful selection of well-known authors, editors, and contributors. Originally widely known as the ""Willardson and Beer"" Series, it has succeeded in publishing numerous landmark volumes and chapters. The series publishes timely, highly relevant volumes intended for long-term impact and reflecting the truly interdisciplinary nature of the field. The volumes in Semiconductors and Semimetals have been and will continue to be of great interest to physicists, chemists, materials scientists, and device engineers in academia, scient

  17. Semiconductor electrochemistry

    CERN Document Server

    Memming, Rüdiger

    2015-01-01

    Providing both an introduction and an up-to-date survey of the entire field, this text captivates the reader with its clear style and inspiring, yet solid presentation. The significantly expanded second edition of this milestone work is supplemented by a completely new chapter on the hot topic of nanoparticles and includes the latest insights into the deposition of dye layers on semiconductor electrodes. In his monograph, the acknowledged expert Professor Memming primarily addresses physical and electrochemists, but materials scientists, physicists, and engineers dealing with semiconductor technology and its applications will also benefit greatly from the contents.

  18. Semiconductor statistics

    CERN Document Server

    Blakemore, J S

    1962-01-01

    Semiconductor Statistics presents statistics aimed at complementing existing books on the relationships between carrier densities and transport effects. The book is divided into two parts. Part I provides introductory material on the electron theory of solids, and then discusses carrier statistics for semiconductors in thermal equilibrium. Of course a solid cannot be in true thermodynamic equilibrium if any electrical current is passed; but when currents are reasonably small the distribution function is but little perturbed, and the carrier distribution for such a """"quasi-equilibrium"""" co

  19. Semiconductor Detectors; Detectores de Semiconductores

    Energy Technology Data Exchange (ETDEWEB)

    Cortina, E.

    2007-07-01

    Particle detectors based on semiconductor materials are among the few devices used for particle detection that are available to the public at large. In fact we are surrounded by them in our daily lives: they are used in photoelectric cells for opening doors, in digital photographic and video camera, and in bar code readers at supermarket cash registers. (Author)

  20. Quasi-perpetual discharge behaviour in p-type Ge-air batteries.

    Science.gov (United States)

    Ocon, Joey D; Kim, Jin Won; Abrenica, Graniel Harne A; Lee, Jae Kwang; Lee, Jaeyoung

    2014-11-07

    Metal-air batteries continue to become attractive energy storage and conversion systems due to their high energy and power densities, safer chemistries, and economic viability. Semiconductor-air batteries - a term we first define here as metal-air batteries that use semiconductor anodes such as silicon (Si) and germanium (Ge) - have been introduced in recent years as new high-energy battery chemistries. In this paper, we describe the excellent doping-dependent discharge kinetics of p-type Ge anodes in a semiconductor-air cell employing a gelled KOH electrolyte. Owing to its Fermi level, n-type Ge is expected to have lower redox potential and better electronic conductivity, which could potentially lead to a higher operating voltage and better discharge kinetics. Nonetheless, discharge measurements demonstrated that this prediction is only valid at the low current regime and breaks down at the high current density region. The p-type Ge behaves extremely better at elevated currents, evident from the higher voltage, more power available, and larger practical energy density from a very long discharge time, possibly arising from the high overpotential for surface passivation. A primary semiconductor-air battery, powered by a flat p-type Ge as a multi-electron anode, exhibited an unprecedented full discharge capacity of 1302.5 mA h gGe(-1) (88% anode utilization efficiency), the highest among semiconductor-air cells, notably better than new metal-air cells with three-dimensional and nanostructured anodes, and at least two folds higher than commercial Zn-air and Al-air cells. We therefore suggest that this study be extended to doped-Si anodes, in order to pave the way for a deeper understanding on the discharge phenomena in alkaline metal-air conversion cells with semiconductor anodes for specific niche applications in the future.

  1. Impurities, Defects and Diffusion in Semiconductors: Bulk and Layered Structures. Materials Research Society Symposium Proceedings. Volume 163

    Science.gov (United States)

    1990-11-21

    Processing and Science, D.B. Poker, C. Ortiz, 1989, ISBN: 1-55899-025-9 Volume 153-Interfaces Between Polymers , Metals, and Ceramics, B.M. DeKoven, A.J...Interfaces in Composite Materials, C.G. Pantano, E.J.H. Chen, 1989, ISBN 1-55899-058-5 Volume 171- Polymer Based Molecular Composites, D.W. Schaefer, J.E...electrical characteristics of a semiconductor such as its free carrier concentration, mobility and minority cartier lifetime are determined by the

  2. Toward High Performance Integrated Semiconductor Micro and Nano Lasers Enabled by Transparent Conducting Materials: from Thick Structure to Thin Film

    Science.gov (United States)

    Ou, Fang

    Integrated semiconductor lasers working at the wavelength around 1.3 microm and 1.55 microm are of great interest for the research of photonic integrated circuit (PIC) since they are the crucial components for optical communications and many other applications. To satisfy the requirement of the next generation optical communication and computing systems, integrated semiconductor lasers are expected to have high device performance like very low lasing threshold, high output powers, high speed and possibility of being integrated with electronics. This dissertation focuses on the design and realization of InP based high performance electrically pumped integrated semiconductor lasers. In the dissertation, we first design the tall structure based electrically pumped integrated micro-lasers. Those lasers are capable of giving >10 mW output power with a moderate low threshold current density (0.5--5 kA/cm 2). Besides, a new enhanced radiation loss based coupler design is demonstrated to realize single directional output for curvilinear cavities. Second, the thin film structure based integrated semiconductor laser designs are proposed. Both structures use the side conduction geometry to enable the electrical injection into the thin film laser cavity. The performance enhancement of the thin film structure based lasers is analyzed compared to the tall structure. Third, we investigate the TCO materials. CdO deposited by PLD and In 2O3 deposited by IAD are studied from aspects of their physical, optical and electrical properties. Those materials can give a wide range of tunability in their conductivity (1--5000 S/cm) and optical transparency (loss 200--5000 cm-1), which is of great interest in realizing novel nanophotonic devices. In addition, the electrical contact properties of those materials to InP are also studied. Experiment result shows that both CdO and In2O3 can achieve good ohmic contact to n-InP with contact resistance as low as 10-6O·cm 2. At last, we investigate

  3. Local control of emission energy of semiconductor quantum dots using volume expansion of a phase-change material

    Science.gov (United States)

    Takahashi, Motoki; Syafawati Humam, Nurrul; Tsumori, Nobuhiro; Saiki, Toshiharu; Regreny, Philippe; Gendry, Michel

    2013-03-01

    A method is proposed to precisely control the emission energy of semiconductor quantum dots (QDs) by the application of local strain due to volume expansion of a phase-change material (GeSbTe) upon amorphization. The feasibility of the method is experimentally demonstrated using photoluminescence (PL) spectroscopy of single InAs/InP QDs on which a GeSbTe thin film is deposited. A significant red-shift of the PL peak energy upon amorphization and subsequent recovery by recrystallization with laser annealing were observed.

  4. Synthesis of Semiconductor Nanocrystals, Focusing on Nontoxic and Earth-Abundant Materials.

    Science.gov (United States)

    Reiss, Peter; Carrière, Marie; Lincheneau, Christophe; Vaure, Louis; Tamang, Sudarsan

    2016-09-28

    We review the synthesis of semiconductor nanocrystals/colloidal quantum dots in organic solvents with special emphasis on earth-abundant and toxic heavy metal free compounds. Following the Introduction, section 2 defines the terms related to the toxicity of nanocrystals and gives a comprehensive overview on toxicity studies concerning all types of quantum dots. Section 3 aims at providing the reader with the basic concepts of nanocrystal synthesis. It starts with the concepts currently used to describe the nucleation and growth of monodisperse particles and next takes a closer look at the chemistry of the inorganic core and its interactions with surface ligands. Section 4 reviews in more detail the synthesis of different families of semiconductor nanocrystals, namely elemental group IV compounds (carbon nanodots, Si, Ge), III-V compounds (e.g., InP, InAs), and binary and multinary metal chalcogenides. Finally, the authors' view on the perspectives in this field is given.

  5. Composite THz materials using aligned metallic and semiconductor microwires, experiments and interpretation

    OpenAIRE

    Mazhorova, Anna; Gu, Jian Feng; Dupuis, Alexandre; Tsuneyuki, Ozaki; Paccianti, Marco; Morandotti, Roberto; MINAMIDE, Hiroaki; Tang, Ming; Wang, Yuye; Ito, Hiromasa; Skorobogatiy, Maksim

    2010-01-01

    We report fabrication method and THz characterization of composite films containing either aligned metallic (tin alloy) microwires or chalcogenide As2Se3 microwires. The microwire arrays are made by stack-and-draw fiber fabrication technique using multi-step co-drawing of low-melting-temperature metals or semiconductor glasses together with polymers. Fibers are then stacked together and pressed into composite films. Transmission through metamaterial films is studied in the whole THz range (0....

  6. Semiconductor bridge (SCB) detonator

    Science.gov (United States)

    Bickes, Jr., Robert W.; Grubelich, Mark C.

    1999-01-01

    The present invention is a low-energy detonator for high-density secondary-explosive materials initiated by a semiconductor bridge igniter that comprises a pair of electrically conductive lands connected by a semiconductor bridge. The semiconductor bridge is in operational or direct contact with the explosive material, whereby current flowing through the semiconductor bridge causes initiation of the explosive material. Header wires connected to the electrically-conductive lands and electrical feed-throughs of the header posts of explosive devices, are substantially coaxial to the direction of current flow through the SCB, i.e., substantially coaxial to the SCB length.

  7. EDITORIAL: Oxide semiconductors

    Science.gov (United States)

    Kawasaki, M.; Makino, T.

    2005-04-01

    Blue or ultraviolet semiconducting light-emitting diodes have the potential to revolutionize illumination systems in the near-future. Such industrial need has propelled the investigation of several wide-gap semiconducting materials in recent years. Commercial applications include blue lasers for DVD memory and laser printers, while military applications are also expected. Most of the material development has so far been focused on GaN (band gap 3.5 eV at 2 K), and ZnSe (2.9 eV) because these two representative direct transition semiconductors are known to be bright emitting sources. GaN and GaN-based alloys are emerging as the winners in this field because ZnSe is subject to defect formation under high current drive. On the other hand, another II-VI compound, ZnO, has also excited substantial interest in the optoelectronics-oriented research communities because it is the brightest emitter of all, owing to the fact that its excitons have a 60 meV binding energy. This is compared with 26 meV for GaN and 20 meV for ZnSe. The stable excitons could lead to laser action based on their recombination even at temperatures well above room temperature. ZnO has additional major properties that are more advantageous than other wide-gap materials: availability of large area substrates, higher energy radiation stability, environmentally-friendly ingredients, and amenability to wet chemical etching. However, ZnO is not new to the semiconductor field as exemplified by several studies made during the 1960s on structural, vibrational, optical and electrical properties (Mollwo E 1982 Landolt-Boernstein New Series vol 17 (Berlin: Springer) p 35). In terms of devices, the luminescence from light-emitting diode structures was demonstrated in which Cu2O was used as the p-type material (Drapak I T 1968 Semiconductors 2 624). The main obstacle to the development of ZnO has been the lack of reproducible p-type ZnO. The possibility of achieving epitaxial p-type layers with the aid of thermal

  8. Sensitization of p-type NiO using n-type conducting polymers

    NARCIS (Netherlands)

    Chavhan, S.D.; Abellon, R.D.; Breemen, A.J.J.M. van; Koetse, M.M.; Sweelssen, J.; Savenije, T.J.

    2010-01-01

    We report on the sensitization of a p-type inorganic semiconductor, NiO, by n-type conjugated polymers. NiO thin films were deposited using RF sputtering in pure Ar (NiO A) or in Ar + O2 (90% + 10%) (NiO B). XPS and Kelvin probe measurements indicate the incorporation of oxygen in NiO B

  9. Sensitization of p-type NiO using n-type conducting polymers

    NARCIS (Netherlands)

    Chavhan, S.D.; Abellon, R.D.; Breemen, A.J.J.M. van; Koetse, M.M.; Sweelssen, J.; Savenije, T.J.

    2010-01-01

    We report on the sensitization of a p-type inorganic semiconductor, NiO, by n-type conjugated polymers. NiO thin films were deposited using RF sputtering in pure Ar (NiO A) or in Ar + O2 (90% + 10%) (NiO B). XPS and Kelvin probe measurements indicate the incorporation of oxygen in NiO B l

  10. Sensitization of p-type NiO using n-type conducting polymers

    NARCIS (Netherlands)

    Chavhan, S.D.; Abellon, R.D.; Breemen, A.J.J.M. van; Koetse, M.M.; Sweelssen, J.; Savenije, T.J.

    2010-01-01

    We report on the sensitization of a p-type inorganic semiconductor, NiO, by n-type conjugated polymers. NiO thin films were deposited using RF sputtering in pure Ar (NiO A) or in Ar + O2 (90% + 10%) (NiO B). XPS and Kelvin probe measurements indicate the incorporation of oxygen in NiO B l

  11. Structural change and power factor enhancement of thermoelectric p-type films

    Energy Technology Data Exchange (ETDEWEB)

    Rothe, Katrin; Leipner, Hartmut; Heyroth, Frank [Interdisziplinaeres Zentrum fuer Materialwissenschaften, Martin-Luther-Universitaet 06099 Halle (Germany); Stordeur, Matthias; Engers, Bernd [angaris GmbH, Heinrich-Damerow-Str. 1, 06120 Halle (Germany)

    2008-07-01

    By sputter-deposition thin films of the thermoelectric effective p-type compound semiconductor (Bi{sub 0.15}Sb{sub 0.85}){sub 2}Te{sub 3} were prepared. For the first time a distinct increase of the electrical conductivity s was observed after heating of the as-deposited films and afterwards cooling. For the enlightenment of this typical behavior, which seems to be similar found for phase change materials consisting of (Ge, Sb, Te)-alloys, also the Seebeck (S) and the Hall coefficient were measured. It was established that the increase of the electrical conductivity is not connected with an expected decrease of the Seebeck coefficient, because the charge carrier density is reduced but at the same time the hole mobility is increasing. Corresponding analytical investigations by XRD, EDX, and REM shows that besides a grain growth in the polycrystalline films a Te-rich phase appears after the heat treatment. The increase of the electrical conductivity at nearly unchanged Seebeck coefficient can be exploited for the enhancement of the film power factor (S{sup 2}s). This is important for the efficiency of thermoelectric thin films devices as miniaturized coolers, generators, and sensors. Nevertheless for a quantitative interpretation of the presented new experimental results further investigations and theoretical considerations are required.

  12. Development in p-type Doping of ZnO

    Institute of Scientific and Technical Information of China (English)

    YU Liping; ZHU Qiqiang; FAN Dayong; LAN Zili

    2012-01-01

    Zinc oxide (ZnO) is a wide band-gap material of the Ⅱ-Ⅵ group with excellent optical properties for optoelectronics applications,such as the flat panel displays and solar cells used in sports tournament.Despite its advantages,the application of ZnO is hampered by the lack of stable p-type doping.In this paper,the recent progress in this field was briefly reviewed,and a comprehensive summary of the research was carried out on ZnO fabrication methods and its electrical,optical,and magnetic properties were presented.

  13. Integrated Materials Design of Organic Semiconductors for Field-Effect Transistors

    KAUST Repository

    Mei, Jianguo

    2013-05-08

    The past couple of years have witnessed a remarkable burst in the development of organic field-effect transistors (OFETs), with a number of organic semiconductors surpassing the benchmark mobility of 10 cm2/(V s). In this perspective, we highlight some of the major milestones along the way to provide a historical view of OFET development, introduce the integrated molecular design concepts and process engineering approaches that lead to the current success, and identify the challenges ahead to make OFETs applicable in real applications. © 2013 American Chemical Society.

  14. Practical Issues for Atom Probe Tomography Analysis of III-Nitride Semiconductor Materials

    OpenAIRE

    2015-01-01

    This is the author accepted manuscript. The final version is available from Cambridge University Press via http://dx.doi.org/10.1017/S1431927615000422 Various practical issues affecting atom probe tomography (APT) analysis of III-nitride semiconductors have been studied as part of an investigation using a c-plane InAlN/GaN heterostructure. Specimen preparation was undertaken using a focused ion beam microscope with a mono-isotopic Ga source. This enabled the unambiguous observation of impl...

  15. Advances in graphene-based semiconductor photocatalysts for solar energy conversion: fundamentals and materials engineering

    Science.gov (United States)

    Xie, Xiuqiang; Kretschmer, Katja; Wang, Guoxiu

    2015-08-01

    Graphene-based semiconductor photocatalysis has been regarded as a promising technology for solar energy storage and conversion. In this review, we summarized recent developments of graphene-based photocatalysts, including preparation of graphene-based photocatalysts, typical key advances in the understanding of graphene functions for photocatalytic activity enhancement and methodologies to regulate the electron transfer efficiency in graphene-based composite photocatalysts, by which we hope to offer enriched information to harvest the utmost fascinating properties of graphene as a platform to construct efficient graphene-based composite photocatalysts for solar-to-energy conversion.

  16. Liquid-crystalline ordering as a concept in materials science: from semiconductors to stimuli-responsive devices.

    Science.gov (United States)

    Fleischmann, Eva-Kristina; Zentel, Rudolf

    2013-08-19

    While the unique optical properties of liquid crystals (LCs) are already well exploited for flat-panel displays, their intrinsic ability to self-organize into ordered mesophases, which are intermediate states between crystal and liquid, gives rise to a broad variety of additional applications. The high degree of molecular order, the possibility for large scale orientation, and the structural motif of the aromatic subunits recommend liquid-crystalline materials as organic semiconductors, which are solvent-processable and can easily be deposited on a substrate. The anisotropy of liquid crystals can further cause a stimuli-responsive macroscopic shape change of cross-linked polymer networks, which act as reversibly contracting artificial muscles. After illustrating the concept of liquid-crystalline order in this Review, emphasis will be placed on synthetic strategies for novel classes of LC materials, and the design and fabrication of active devices.

  17. Semiconductor Optics

    CERN Document Server

    Klingshirn, Claus F

    2012-01-01

    This updated and enlarged new edition of Semiconductor Optics provides an introduction to and an overview of semiconductor optics from the IR through the visible to the UV, including linear and nonlinear optical properties, dynamics, magneto and electrooptics, high-excitation effects and laser processes, some applications, experimental techniques and group theory. The mathematics is kept as elementary as possible, sufficient for an intuitive understanding of the experimental results and techniques treated. The subjects covered extend from physics to materials science and optoelectronics. Significantly updated chapters add coverage of current topics such as electron hole plasma, Bose condensation of excitons and meta materials. Over 120 problems, chapter introductions and a detailed index make it the key textbook for graduate students in physics. The mathematics is kept as elementary as possible, sufficient for an intuitive understanding of the experimental results and techniques treated. The subjects covered ...

  18. Semiconductor Physical Electronics

    CERN Document Server

    Li, Sheng

    2006-01-01

    Semiconductor Physical Electronics, Second Edition, provides comprehensive coverage of fundamental semiconductor physics that is essential to an understanding of the physical and operational principles of a wide variety of semiconductor electronic and optoelectronic devices. This text presents a unified and balanced treatment of the physics, characterization, and applications of semiconductor materials and devices for physicists and material scientists who need further exposure to semiconductor and photonic devices, and for device engineers who need additional background on the underlying physical principles. This updated and revised second edition reflects advances in semicondutor technologies over the past decade, including many new semiconductor devices that have emerged and entered into the marketplace. It is suitable for graduate students in electrical engineering, materials science, physics, and chemical engineering, and as a general reference for processing and device engineers working in the semicondi...

  19. Semiconductor devices incorporating multilayer interference regions

    Science.gov (United States)

    Biefeld, Robert M.; Drummond, Timothy J.; Gourley, Paul L.; Zipperian, Thomas E.

    1990-01-01

    A semiconductor high reflector comprising a number of thin alternating layers of semiconductor materials is electrically tunable and may be used as a temperature insensitive semiconductor laser in a Fabry-Perot configuration.

  20. Chemical Vapor Deposition Growth of Degenerate p-Type Mo-Doped ReS2 Films and Their Homojunction.

    Science.gov (United States)

    Qin, Jing-Kai; Shao, Wen-Zhu; Xu, Cheng-Yan; Li, Yang; Ren, Dan-Dan; Song, Xiao-Guo; Zhen, Liang

    2017-05-10

    Substitutional doping of transition metal dichalcogenide two-dimensional materials has proven to be effective in tuning their intrinsic properties, such as band gap, transport characteristics, and magnetism. In this study, we realized substitutional doping of monolayer rhenium disulfide (ReS2) with Mo via chemical vapor deposition. Scanning transmission electron microscopy demonstrated that Mo atoms are successfully doped into ReS2 by substitutionally replacing Re atoms in the lattice. Electrical measurements revealed the degenerate p-type semiconductor behavior of Mo-doped ReS2 field effect transistors, in agreement with density functional theory calculations. The p-n diode device based on a doped ReS2 and ReS2 homojunction exhibited gate-tunable current rectification behaviors, and the maximum rectification ratio could reach up to 150 at Vd = -2/+2 V. The successful synthesis of p-type ReS2 in this study could largely promote its application in novel electronic and optoelectronic devices.

  1. Use of a laser for the spectral analysis of semiconductor materials

    Science.gov (United States)

    Karyakin, A. V.; Akhmanova, M. V.; Kaygorodov, V. A.

    1978-01-01

    Conventional applications of lasers for emission spectroscopy involving direct recording of light pulses of an evaporated substance emitted from the sample under the action of the laser light (direct method) were examined. Use of the laser light for conversion of the substance to a vapor and feeding the vapors into the conventional source of emission such as arc, sparks, etc. (the so called 2 stage excitation) were studied for use in the spectral analysis, of semiconductors. The direct method has a high reproducibility (5-7%); the 2 stage excitation method, characterized by the same intensity as obtained with the conventional constant, current arc, has better reproducibility than the direct method (15-20%). Both methods can be used for the analysis of samples without prior preparation. Advantages of these methods are the elimination of impurities picked up during trituration of the samples into powders and shortening of the analytical procedures.

  2. Characterisation of Semiconductor Materials/Device Structures using SIMS (Review Paper

    Directory of Open Access Journals (Sweden)

    Anuradha Dhaul

    2009-07-01

    Full Text Available Secondary ion mass spectrometry (SIMS is an analytical technique that can be used to characterise the surface and near-surface region of solids. The instrument operation and data analysis have been discussed to obtain meaningful results. The paper discusses the technique of sequential sputtering to elucidate the thickness of individual layers in a multilayer structure. The application of the technique for failure analysis, standard generation and interface studies have been discussed in detail taking examples of multilayer structures of compound semiconductors being developed at SSPL.Defence Science Journal, 2009, 59(4, pp.342-350, DOI:http://dx.doi.org/10.14429/dsj.59.1532

  3. Surface Tension Directed Fluidic Self-Assembly of Semiconductor Chips across Length Scales and Material Boundaries

    Directory of Open Access Journals (Sweden)

    Shantonu Biswas

    2016-03-01

    Full Text Available This publication provides an overview and discusses some challenges of surface tension directed fluidic self-assembly of semiconductor chips which are transported in a liquid medium. The discussion is limited to surface tension directed self-assembly where the capture, alignment, and electrical connection process is driven by the surface free energy of molten solder bumps where the authors have made a contribution. The general context is to develop a massively parallel and scalable assembly process to overcome some of the limitations of current robotic pick and place and serial wire bonding concepts. The following parts will be discussed: (2 Single-step assembly of LED arrays containing a repetition of a single component type; (3 Multi-step assembly of more than one component type adding a sequence and geometrical shape confinement to the basic concept to build more complex structures; demonstrators contain (3.1 self-packaging surface mount devices, and (3.2 multi-chip assemblies with unique angular orientation. Subsequently, measures are discussed (4 to enable the assembly of microscopic chips (10 μm–1 mm; a different transport method is introduced; demonstrators include the assembly of photovoltaic modules containing microscopic silicon tiles. Finally, (5 the extension to enable large area assembly is presented; a first reel-to-reel assembly machine is realized; the machine is applied to the field of solid state lighting and the emerging field of stretchable electronics which requires the assembly and electrical connection of semiconductor devices over exceedingly large area substrates.

  4. Development and Processing of p-type Oxide Thermoelectric Materials

    DEFF Research Database (Denmark)

    Wu, NingYu; Van Nong, Ngo

    have attracted much attention due to features such as a natural abundance of constituent elements, environmental benignity and durability at high temperature in air. This research aims to develop and investigate the misfit-layered cobaltate Ca3Co4O9+δ, which demonstrates a large potential for high......-combustion reaction for the synthesis of Ca3Co4O9+δ nano-powder is developed to realize nanostructuring for enhanced thermoelectric properties. The procedure is a modification of the conventional citrate–nitrate sol–gel method where an auto-combustion process is initiated by a controlled thermal oxidation...

  5. Method of doping a semiconductor

    Science.gov (United States)

    Yang, Chiang Y.; Rapp, Robert A.

    1983-01-01

    A method for doping semiconductor material. An interface is established between a solid electrolyte and a semiconductor to be doped. The electrolyte is chosen to be an ionic conductor of the selected impurity and the semiconductor material and electrolyte are jointly chosen so that any compound formed from the impurity and the semiconductor will have a free energy no lower than the electrolyte. A potential is then established across the interface so as to allow the impurity ions to diffuse into the semiconductor. In one embodiment the semiconductor and electrolyte may be heated so as to increase the diffusion coefficient.

  6. Nitrogen-monoxide gas-sensing properties of transparent p-type copper-oxide nanorod arrays

    Energy Technology Data Exchange (ETDEWEB)

    Park, Soojeong; Kim, Hyojin; Kim, Dojin [Chungnam National University, Daejeon (Korea, Republic of)

    2015-01-15

    We report the nitrogen-monoxide (NO) gas-sensing properties of transparent p-type copper-oxide (CuO) nanorod arrays synthesized by using the hydrothermal method with a CuO nanoparticle seed layer deposited on a glass substrate via sputtering process. We synthesized polycrystalline CuO nanorods measuring 200 to 300 nm in length and 20 to 30 nm in diameter for three controlled molarity ratios of 1:1, 1:2 and 1:4 between copper nitrate trihydrate [Cu(NO{sub 2}){sub 2}·3H{sub 2}O] and hexamethylenetetramine (C{sub 6}H{sub 12}N{sub 4}). The crystal structures and morphologies of the synthesized CuO nanorod arrays were examined using grazing incidence X-ray diffraction and scanning electron microscopy. The gas-sensing measurements for NO gas in dry air indicated that the CuO nanorodarray-based gas sensors synthesized under hydrothermal condition at a molarity ratio of 1:2 showed the best gas sensing response to NO gas. These CuO nanorod-array gas sensors exhibited a highly sensitive response to NO gas, with a maximum sensitivity of about 650% for 10 ppm NO in dry air at an operating temperature of 100 .deg. C. These transparent p-type CuO nanorod-array gas sensors have shown a reversible and reliable response to NO gas over a range of operating temperatures. These results indicate certain potential use of p-type oxide semiconductor CuO nanorods as sensing materials for several types of gas sensors, including p - n junction gas sensors.

  7. Ionic and electronic behaviors of earth-abundant semiconductor materials and their applications toward solar energy harvesting

    Science.gov (United States)

    Mayer, Matthew T.

    Semiconductor devices offer promise for efficient conversion of sunlight into other useful forms of energy, in either photovoltaic or photoelectrochemical cell configurations to produce electrical power or chemical energy, respectively. This dissertation examines ionic and electronic phenomena in some candidate semiconductors and seeks to understand their implications toward solar energy conversion applications. First, copper sulfide (Cu2S) was examined as a candidate photovoltaic material. It was discovered that its unique property of cation diffusion allows the room-temperature synthesis of vertically-aligned nanowire arrays, a morphology which facilitates study of the diffusion processes. This diffusivity was found to induce hysteresis in the electronic behavior, leading to the phenomena of resistive switching and negative differential resistance. The Cu2S were then demonstrated as morphological templates for solid-state conversion into different types of heterostructures, including segmented and rod-in-tube morphologies. Near-complete conversion to ZnS, enabled by the out-diffusion of Cu back into the substrate, was also achieved. While the ion diffusion property likely hinders the reliability of Cu 2S in photovoltaic applications, it was shown to enable useful electronic and ionic behaviors. Secondly, iron oxide (Fe2O3, hematite) was examined as a photoanode for photoelectrochemical water splitting. Its energetic limitations toward the water electrolysis reactions were addressed using two approaches aimed at achieving greater photovoltages and thereby improved water splitting efficiencies. In the first, a built-in n-p junction produced an internal field to drive charge separation and generate photovoltage. In the second, Fe 2O3 was deposited onto a smaller band gap material, silicon, to form a device capable of producing enhanced total photovoltage by a dual-absorber Z-scheme mechanism. Both approaches resulted in a cathodic shift of the photocurrent onset

  8. High voltage semiconductor devices and methods of making the devices

    Energy Technology Data Exchange (ETDEWEB)

    Matocha, Kevin; Chatty, Kiran; Banerjee, Sujit

    2017-02-28

    A multi-cell MOSFET device including a MOSFET cell with an integrated Schottky diode is provided. The MOSFET includes n-type source regions formed in p-type well regions which are formed in an n-type drift layer. A p-type body contact region is formed on the periphery of the MOSFET. The source metallization of the device forms a Schottky contact with an n-type semiconductor region adjacent the p-type body contact region of the device. Vias can be formed through a dielectric material covering the source ohmic contacts and/or Schottky region of the device and the source metallization can be formed in the vias. The n-type semiconductor region forming the Schottky contact and/or the n-type source regions can be a single continuous region or a plurality of discontinuous regions alternating with discontinuous p-type body contact regions. The device can be a SiC device. Methods of making the device are also provided.

  9. CuNb3O8: A p-Type Semiconducting Metal Oxide Photoelectrode.

    Science.gov (United States)

    Joshi, Upendra A; Maggard, Paul A

    2012-06-07

    A new p-type CuNb3O8 polycrystalline photoelectrode was investigated and was determined to have indirect and direct bandgap sizes of 1.26 and 1.47 eV, respectively. The p-type polycrystalline film could be prepared on fluorine-doped tin oxide glass and yielded a cathodic photocurrent under visible-light irradiation (λ > 420 nm) with incident photon-to-current efficiencies of up to ∼6-7% and concomitant hydrogen evolution. A Mott-Schottky analysis yielded a flat band potential of +0.35 V versus RHE (pH = 6.3) and a calculated p-type dopant concentration of ∼7.2 × 10(15) cm(-3). The conduction band energies are found to be negative enough for the reduction of water under visible light irradiation. A hole mobility of ∼145 cm(2)/V·s was obtained from J(I)-V(2) measurements using the Mott-Gurney relation, which is ∼50% higher than that typically found for p-type Cu2O. DFT-based electronic structure calculations were used to probe the atomic and structural origins of the band gap transitions and carrier mobility. Thus, a new p-type semiconductor is discovered for potential applications in solar energy conversion.

  10. Kelvin Force Microscopy and corona charging for semiconductor material and device characterization

    Science.gov (United States)

    Marinskiy, Dmitriy; Edelman, Piotr; Lagowski, Jacek; Loy, Thye Chong; Almeida, Carlos; Savtchouk, Alexandre

    2016-11-01

    Novel developments in this review relate to μcorona-Kelvin, realized by miniaturization of corona charging spot and adaptation of Kelvin Force Microscopy, KFM. Resolution improvement has opened possibilities of non-contact characterization of miniature scribe line test sites on processed semiconductor wafers. Surface diffusion of corona ions can be quantified with μcorona-KFM leading to the development of the kinetic C-V method. The quantified decrease of charge due to diffusion creates a "charge-bias sweep". Application examples illustrate the determination of dielectric capacitance; flatband voltage; and effective gate metal work function indicators. Applications to SiC demonstrate doping density determination with kinetic CV. Non-Visible Defect, NVD, inspection benefits from micro-resolution characterization in two ways: 1) defects revealed by whole wafer mapping can now be examined in high resolution; illustrated using an example of Na contamination; and 2) detailed characterization can be performed within small defective areas providing a means for better understanding of a specific NVD.

  11. Thin film solid-state reactions forming carbides as contact materials for carbon-containing semiconductors

    Science.gov (United States)

    Leroy, W. P.; Detavernier, C.; Van Meirhaeghe, R. L.; Lavoie, C.

    2007-03-01

    Metal carbides are good candidates to contact carbon-based semiconductors (SiC, diamond, and carbon nanotubes). Here, we report on an in situ study of carbide formation during the solid-state reaction between thin films. The solid-state reaction was examined between 11 transition metals (W, Mo, Fe, Cr, V, Nb, Mn, Ti, Ta, Zr, and Hf) and an amorphous carbon layer. Capping layers (C or TiN) of different thicknesses were applied to prevent oxidation. Carbide formation is evidenced for nine metals and the phases formed have been identified (for a temperature ranging from 100to1100°C). W first forms W2C and then WC; Mo forms Mo2C; Fe forms Fe3C; Cr first forms metastable phases Cr2C and Cr3C2-x, and finally forms Cr3C2; V forms VCx; Nb transforms into Nb2C followed by NbC; Ti forms TiC; Ta first forms Ta2C and then TaC; and Hf transforms into HfC. The activation energy for the formation of the various carbide phases has been obtained by in situ x-ray diffraction.

  12. Amphoteric oxide semiconductors for energy conversion devices: a tutorial review.

    Science.gov (United States)

    Singh, Kalpana; Nowotny, Janusz; Thangadurai, Venkataraman

    2013-03-07

    In this tutorial review, we discuss the defect chemistry of selected amphoteric oxide semiconductors in conjunction with their significant impact on the development of renewable and sustainable solid state energy conversion devices. The effect of electronic defect disorders in semiconductors appears to control the overall performance of several solid-state ionic devices that include oxide ion conducting solid oxide fuel cells (O-SOFCs), proton conducting solid oxide fuel cells (H-SOFCs), batteries, solar cells, and chemical (gas) sensors. Thus, the present study aims to assess the advances made in typical n- and p-type metal oxide semiconductors with respect to their use in ionic devices. The present paper briefly outlines the key challenges in the development of n- and p-type materials for various applications and also tries to present the state-of-the-art of defect disorders in technologically related semiconductors such as TiO(2), and perovskite-like and fluorite-type structure metal oxides.

  13. ASTM E 1559 method for measuring material outgassing/deposition kinetics has applications to aerospace, electronics, and semiconductor industries

    Science.gov (United States)

    Garrett, J. W.; Glassford, A. P. M.; Steakley, J. M.

    1994-01-01

    The American Society for Testing and Materials has published a new standard test method for characterizing time and temperature-dependence of material outgassing kinetics and the deposition kinetics of outgassed species on surfaces at various temperatures. This new ASTM standard, E 1559(1), uses the quartz crystal microbalance (QCM) collection measurement approach. The test method was originally developed under a program sponsored by the United States Air Force Materials Laboratory (AFML) to create a standard test method for obtaining outgassing and deposition kinetics data for spacecraft materials. Standardization by ASTM recognizes that the method has applications beyond aerospace. In particular, the method will provide data of use to the electronics, semiconductor, and high vacuum industries. In ASTM E 1559 the material sample is held in vacuum in a temperature-controlled effusion cell, while its outgassing flux impinges on several QCM's which view the orifice of the effusion cell. Sample isothermal total mass loss (TML) is measured as a function of time from the mass collected on one of the QCM's which is cooled by liquid nitrogen, and the view factor from this QCM to the cell. The amount of outgassed volatile condensable material (VCM) on surfaces at higher temperatures is measured as a function of time during the isothermal outgassing test by controlling the temperatures of the remaining QCM's to selected values. The VCM on surfaces at temperatures in between those of the collector QCM's is determined at the end of the isothermal test by heating the QCM's at a controlled rate and measuring the mass loss from the end of the QCM's as a function of time and temperature. This reevaporation of the deposit collected on the QCM's is referred to as QCM thermogravimetric analysis. Isothermal outgassing and deposition rates can be determined by differentiating the isothermal TML and VCM data, respectively, while the evaporation rates of the species can be obtained as a

  14. Surface degradation mechanism during the fluorine-based plasma etching of a low-k material for nanoscale semiconductors.

    Science.gov (United States)

    Kim, Jong Kyu; Kang, Seung Hyun; Cho, Sung Il; Lee, Sung Ho; Kim, Kyong Nam; Yeom, G Y

    2014-12-01

    The degradation of a low-k material surface during the exposure to plasma etching is one of the most serious problems to be solved for the realization of high speed semiconductor devices. In this study, the factors causing the degradation of a low-k material surface during the etching using fluorine-based plasma etching have been investigated by using XPS. As the plasma factors, active radicals, bombardment energy, and charge of the ions were considered and, as the low-k material, methyl silsesquioxane (MSQ) has been used. The XPS results showed that the ion bombardment during the plasma etching of MSQ affects the breaking of MSQ bone structure by changing the Si-O bonds and Si-C bonds to Si-F mostly, while fluorine-based radicals in the plasma mostly affect the change of Si-CH3 bonds to Si-CH(x)F(y). By removing the charge of the ions during the bombardment, the MSQ properties were further improved. When F intensity which is related to the damage of the MSQ surface is estimated, the bombardment energy, reactive radical density, and charge of the ions were responsible for -18%, -53%, -19% of the F intensity in the MSQ. Therefore, by using the neutral beam etching instead of a conventional ICP etching, the degradation on the MSQ surface estimated by the F intensity remaining on the MSQ surface could be decreased to 10%.

  15. Designing small molecule polyaromatic p- and n-type semiconductor materials for organic electronics

    KAUST Repository

    Collis, Gavin E.

    2015-12-22

    By combining computational aided design with synthetic chemistry, we are able to identify core 2D polyaromatic small molecule templates with the necessary optoelectronic properties for p- and n-type materials. By judicious selection of the functional groups, we can tune the physical properties of the material making them amenable to solution and vacuum deposition. In addition to solubility, we observe that the functional group can influence the thin film molecular packing. By developing structure-property relationships (SPRs) for these families of compounds we observe that some compounds are better suited for use in organic solar cells, while others, varying only slightly in structure, are favoured in organic field effect transistor devices. We also find that the processing conditions can have a dramatic impact on molecular packing (i.e. 1D vs 2D polymorphism) and charge mobility; this has implications for material and device long term stability. We have developed small molecule p- and n-type materials for organic solar cells with efficiencies exceeding 2%. Subtle variations in the functional groups of these materials produces p- and ntype materials with mobilities higher than 0.3 cm2/Vs. We are also interested in using our SPR approach to develop materials for sensor and bioelectronic applications.

  16. Designing small molecule polyaromatic p- and n-type semiconductor materials for organic electronics

    Science.gov (United States)

    Collis, Gavin E.

    2015-12-01

    By combining computational aided design with synthetic chemistry, we are able to identify core 2D polyaromatic small molecule templates with the necessary optoelectronic properties for p- and n-type materials. By judicious selection of the functional groups, we can tune the physical properties of the material making them amenable to solution and vacuum deposition. In addition to solubility, we observe that the functional group can influence the thin film molecular packing. By developing structure-property relationships (SPRs) for these families of compounds we observe that some compounds are better suited for use in organic solar cells, while others, varying only slightly in structure, are favoured in organic field effect transistor devices. We also find that the processing conditions can have a dramatic impact on molecular packing (i.e. 1D vs 2D polymorphism) and charge mobility; this has implications for material and device long term stability. We have developed small molecule p- and n-type materials for organic solar cells with efficiencies exceeding 2%. Subtle variations in the functional groups of these materials produces p- and ntype materials with mobilities higher than 0.3 cm2/Vs. We are also interested in using our SPR approach to develop materials for sensor and bioelectronic applications.

  17. P-type ZnO thin films prepared by in situ oxidation of DC sputtered Zn{sub 3}N{sub 2}:Ga

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Jun; Xue Shuwen; Shao Lexi, E-mail: shaolxmail@163.co [School of Physical Science and Technology, Zhanjiang Normal University, Zhanjiang 524048 (China)

    2010-04-15

    The feasibility of a new fabrication route for N and Ga codoped p-type ZnO thin films on glass substrates, consisting of DC sputtering deposition of Zn{sub 3}N{sub 2}:Ga precursors followed by in situ oxidation in high purity oxygen, has been studied. The effects of oxidation temperature on the structural, optical and electrical properties of the samples were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), optical transmittance and Hall effect measurements. The results were compared to a control film without Ga. XRD analyses revealed that the Zn{sub 3}N{sub 2} films entirely transformed into ZnO films after annealing Zn{sub 3}N{sub 2} films in oxygen over 500 {sup 0}C for 2 h. Hall effect measurements confirmed p-type conduction in N and Ga codoped ZnO films with a low resistivity of 19.8 {Omega} {center_dot} cm, a high hole concentration of 4.6 x 10{sup 18} cm{sup -3} and a Hall mobility of 0.7 cm{sup 2}/(V{center_dot}s). These results demonstrate a promising approach to fabricate low resistivity p-type ZnO with high hole concentration. (semiconductor materials)

  18. Structural stability at high pressure, electronic, and magnetic properties of BaFZnAs: A new candidate of host material of diluted magnetic semiconductors

    Science.gov (United States)

    Bi-Juan, Chen; Zheng, Deng; Xian-Cheng, Wang; Shao-Min, Feng; Zhen, Yuan; Si-Jia, Zhang; Qing-Qing, Liu; Chang-Qing, Jin

    2016-07-01

    The layered semiconductor BaFZnAs with the tetragonal ZrCuSiAs-type structure has been successfully synthesized. Both the in-situ high-pressure synchrotron x-ray diffraction and the high-pressure Raman scattering measurements demonstrate that the structure of BaFZnAs is stable under pressure up to 17.5 GPa at room temperature. The resistivity and the magnetic susceptibility data show that BaFZnAs is a non-magnetic semiconductor. BaFZnAs is recommended as a candidate of the host material of diluted magnetic semiconductor. Project supported by the National Natural Science Foundation of China and Project of Ministry of Science and Technology of China.

  19. Skylab experiments. Volume 3: Materials science. [Skylab experiments on metallurgy, crystal growth, semiconductors, and combustion physics in weightless environment for high school level education

    Science.gov (United States)

    1973-01-01

    The materials science and technology investigation conducted on the Skylab vehicle are discussed. The thirteen experiments that support these investigations have been planned to evaluate the effect of a weightless environment on melting and resolidification of a variety of metals and semiconductor crystals, and on combustion of solid flammable materials. A glossary of terms which define the space activities and a bibliography of related data are presented.

  20. Avoiding bias effects in NMR experiments for heteronuclear dipole-dipole coupling determinations: principles and application to organic semiconductor materials.

    Science.gov (United States)

    Kurz, Ricardo; Cobo, Marcio Fernando; de Azevedo, Eduardo Ribeiro; Sommer, Michael; Wicklein, André; Thelakkat, Mukundan; Hempel, Günter; Saalwächter, Kay

    2013-09-16

    Carbon-proton dipole-dipole couplings between bonded atoms represent a popular probe of molecular dynamics in soft materials or biomolecules. Their site-resolved determination, for example, by using the popular DIPSHIFT experiment, can be challenged by spectral overlap with nonbonded carbon atoms. The problem can be solved by using very short cross-polarization (CP) contact times, however, the measured modulation curves then deviate strongly from the theoretically predicted shape, which is caused by the dependence of the CP efficiency on the orientation of the CH vector, leading to an anisotropic magnetization distribution even for isotropic samples. Herein, we present a detailed demonstration and explanation of this problem, as well as providing a solution. We combine DIPSHIFT experiments with the rotor-directed exchange of orientations (RODEO) method, and modifications of it, to redistribute the magnetization and obtain undistorted modulation curves. Our strategy is general in that it can also be applied to other types of experiments for heteronuclear dipole-dipole coupling determinations that rely on dipolar polarization transfer. It is demonstrated with perylene-bisimide-based organic semiconductor materials, as an example, in which measurements of dynamic order parameters reveal correlations of the molecular dynamics with the phase structure and functional properties.

  1. (TMTSF)2X materials and structural implications for low-dimensional polymeric and disordered molecular semiconductors

    DEFF Research Database (Denmark)

    Bechgaard, Klaus; Nielsen, Martin Meedom; Krebs, Frederik C

    2000-01-01

    The structural characteristics and the relation to the electronic properties of three types of molecular materials are discussed. In TMTSF2X salts a triclinic unit cell it suggested to be important in avoiding a 2k(F) Peierls distortion. In polythiophenes appropriate ordering of microcrystallites...

  2. Chemistry and Defects in Semiconductor Heterostructures. Materials Research Society Symposium Proceedings. Volume 148

    Science.gov (United States)

    1990-05-01

    energ7y for an overomowtbh (141. This work was sapported by’he𔃿.lpartmest ofPCro-t-CC-’F D53) r. Jules Soatbort, contract monitor, for which muon...found, indicating a single crystalline material. The patterns, however, are verN sensitive to small non-uniform lattice strains which can be detected to

  3. Photovoltaic semiconductor materials based on alloys of tin sulfide, and methods of production

    Energy Technology Data Exchange (ETDEWEB)

    Lany, Stephan

    2016-06-07

    Photovoltaic thin-film materials comprising crystalline tin sulfide alloys of the general formula Sn.sub.1-x(R).sub.xS, where R is selected from magnesium, calcium and strontium, as well as methods of producing the same, are disclosed.

  4. Recycling of p-type mc-si Top Cuts into p-type mono c-Si Solar Cells

    Energy Technology Data Exchange (ETDEWEB)

    Bronsveld, P.C.P.; Manshanden, P.; Lenzmann, F.O. [ECN Solar Energy, Westerduinweg 3, P.O. Box 1, NL-1755 ZG Petten (Netherlands); Gjerstad, O. [Si Pro Holding AS, Ornesveien 3, P.O. Box 37, 8161, Glomfjord (Norway); Oevrelid, E.J. [SINTEF, Alfred Getz Vei 2, 7465, Trondheim (Norway)

    2013-07-01

    Solar cell results and material analysis are presented of 2 p-type Czochralski (Cz) ingots pulled from a charge consisting of 100% and 50% recycled multicrystalline silicon top cuts. The top cuts were pre-cleaned with a dedicated low energy consuming technology. No structure loss was observed in the bodies of the ingots. The performance of solar cells made from the 100% recycled Si ingot decreases towards the seed end of the ingot, which could be related to a non-optimal pulling process. Solar cells from the tail end of this ingot and from the 50% recycled Si ingot demonstrated an average solar cell efficiency of 18.6%. This is only 0.1% absolute lower than the efficiency of higher resistivity reference solar cells from commercially available wafers that were co-processed.

  5. Method of passivating semiconductor surfaces

    Science.gov (United States)

    Wanlass, Mark W.

    1990-01-01

    A method of passivating Group III-V or II-VI semiconductor compound surfaces. The method includes selecting a passivating material having a lattice constant substantially mismatched to the lattice constant of the semiconductor compound. The passivating material is then grown as an ultrathin layer of passivating material on the surface of the Group III-V or II-VI semiconductor compound. The passivating material is grown to a thickness sufficient to maintain a coherent interface between the ultrathin passivating material and the semiconductor compound. In addition, a device formed from such method is also disclosed.

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

    Science.gov (United States)

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

    2015-12-01

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

  7. Theoretical investigation of the excitonic semiconductor response for varying material thickness: Transition from quantum well to bulk

    DEFF Research Database (Denmark)

    Bischoff, Svend; Knorr, A; Koch, S.W.

    1997-01-01

    For semiconductor slabs with thicknesses varying from the two-dimensional to the three-dimensional limit the linear optical response is calculated numerically by solving the semiconductor Maxwell-Bloch equations. For short-pulse excitation the spatiotemporal dynamics of the electronic mode...

  8. 2D Crystal Semiconductors New Materials for GHz-THz Devices

    Science.gov (United States)

    2015-10-02

    chemical catalysis (MoS2, graphite), lithium–ion batteries (lithium cobaltate and layered carbon), lubricants (MoS2), neutron moderation in nuclear ... reactors (graphite), and thermally and mechani- cally refractory crucibles used in much of electronic material and device processing (BN and graphite). The...SF298 Form Please attach your SF298 form. A blank SF298 can be found here. Please do not password protect or secure the PDF The maximum file size for

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

    Science.gov (United States)

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

    2017-01-01

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

  10. Organic / IV, III-V Semiconductor Hybrid Solar Cells

    Directory of Open Access Journals (Sweden)

    Pang-Leen Ong

    2010-03-01

    Full Text Available We present a review of the emerging class of hybrid solar cells based on organic-semiconductor (Group IV, III-V, nanocomposites, which states separately from dye synthesized, polymer-metal oxides and organic-inorganic (Group II-VI nanocomposite photovoltaics. The structure of such hybrid cell comprises of an organic active material (p-type deposited by coating, printing or spraying technique on the surface of bulk or nanostructured semiconductor (n-type forming a heterojunction between the two materials. Organic components include various photosensitive monomers (e.g., phtalocyanines or porphyrines, conjugated polymers, and carbon nanotubes. Mechanisms of the charge separation at the interface and their transport are discussed. Also, perspectives on the future development of such hybrid cells and comparative analysis with other classes of photovoltaics of third generation are presented.

  11. An efficient strategy for designing ambipolar organic semiconductor material: Introducing dehydrogenated phosphorus atoms into pentacene core

    Science.gov (United States)

    Tang, Xiao-Dan

    2017-09-01

    The charge transport properties of phosphapentacene (P-PEN) derivatives were systematically explored by theoretical calculation. The dehydrogenated P-PENs have reasonable frontier molecular orbital energy levels to facilitate both electron and hole injection. The reduced reorganization energies of dehydrogenated P-PENs could be intimately connected to the bonding nature of phosphorus atoms. From the idea of homology modeling, the crystal structure of TIPSE-4P-2p is constructed and fully optimized. Fascinatingly, TIPSE-4P-2p shows the intrinsic property of ambipolar transport in both hopping and band models. Thus, introducing dehydrogenated phosphorus atoms into pentacene core could be an efficient strategy for designing ambipolar material.

  12. Electron spin resonance investigaton of semiconductor materials for application in thin-film silicon solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Xiao, Lihong

    2012-07-01

    In the present work, hydrogenated silicon and its alloys silicon carbide and silicon oxide have been investigated using electron spin resonance (ESR). The microstructure of these materials ranges from highly crystalline to amorphous. The correlation between the paramagnetic defects, microstructure, optical and electrical properties has been discussed. Correspondingly, these properties were characterized by the spin density (N{sub S}), g-value and the lineshape of ESR spectra, Infrared (I{sup IR}{sub C}) and/or Raman crystallinity (I{sup RS}{sub C}) as well as optical absorption and electrical dark conductivity ({sigma}{sub D}). 1. As the light absorber, Si layers essentially should have low defect density and good stability against light exposure. The spin density (N{sub S}) measured by ESR is often used as a measure for the paramagnetic defect density (N{sub D}) in the material. However, ESR sample preparation procedures can potentially cause discrepancy between N{sub S} and N{sub D}. Using Mo-foil, Al-foil and ZnO:Al-covered glass as sacrificial substrates, {mu}c-Si:H and a-Si:H films were deposited by plasma-enhanced chemical vapor deposition (PECVD), and ESR powder samples have been prepared with corresponding procedures. Possible preparation-related metastability and instability effects have been investigated in terms of substrate dependence, HCl-etching and atmosphere exposure. A sequence of 'preparation - annealing - air-exposure - annealing' has been designed to investigate the metastability and instability effects. N{sub S} after post-preparation air exposure is higher than in the annealed states, especially for the highly crystalline {mu}c-Si:H material the discrepancy reached one order of magnitude. Low temperature ESR measurements at 40 K indicated that atmospheric exposure leads to a redistribution of the defect states which in turn influence the evaluated N{sub S}. In annealed conditions the samples tend to have lower N{sub S} presumably due

  13. Comparison of defects in crystalline oxide semiconductor materials by electron spin resonance

    Energy Technology Data Exchange (ETDEWEB)

    Matsuda, Tokiyoshi, E-mail: toki@rins.ryukoku.ac.jp; Kimura, Mutsumi [Department of Electronics and Informatics, Faculty of Science and Technology, Ryukoku University, 1-438, 1-5 Yokotani, Seta Oe-Cho, Otsu, Shiga 520-2194, Japan and Joint Research Center for Science and Technology, Ryukoku University, 1-5 Yokotani, Seta Oe-Cho, Otsu, Shiga 520-2194 (Japan)

    2015-03-15

    Defects in crystalline InGaZnO{sub 4} (IGZO) induced by plasma were investigated using electron spin resonance (ESR). Thermal stabilities and g factors of two ESR signals (A and B observed at g = 1.939 and 2.003, respectively) in IGZO were different from those of the ESR signals observed in component materials such as Ga{sub 2}O{sub 3} (signal observed at g = 1.969), In{sub 2}O{sub 3} (no signal), and ZnO (signal observed at g = 1.957). Signal A in IGZO increased upon annealing at 300 °C for 1 h, but decreased when annealing was continued for more than 2 h. On the other hand, signal B decreased upon annealing at 300 °C for 1 h. The ESR signal in ZnO decayed in accordance with a second-order decay model with a rate constant of 2.1 × 10{sup −4} s{sup −1}; however, this phenomenon was not observed in other materials. This difference might have been due to randomly formed IGZO lattices such as asymmetrical (Ga, Zn)O and In-O layers. Defects in signals A and B in IGZO were formed in trap states (at the deep level) and tail states, respectively.

  14. Electron spin resonance investigaton of semiconductor materials for application in thin-film silicon solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Xiao, Lihong

    2012-07-01

    In the present work, hydrogenated silicon and its alloys silicon carbide and silicon oxide have been investigated using electron spin resonance (ESR). The microstructure of these materials ranges from highly crystalline to amorphous. The correlation between the paramagnetic defects, microstructure, optical and electrical properties has been discussed. Correspondingly, these properties were characterized by the spin density (N{sub S}), g-value and the lineshape of ESR spectra, Infrared (I{sup IR}{sub C}) and/or Raman crystallinity (I{sup RS}{sub C}) as well as optical absorption and electrical dark conductivity ({sigma}{sub D}). 1. As the light absorber, Si layers essentially should have low defect density and good stability against light exposure. The spin density (N{sub S}) measured by ESR is often used as a measure for the paramagnetic defect density (N{sub D}) in the material. However, ESR sample preparation procedures can potentially cause discrepancy between N{sub S} and N{sub D}. Using Mo-foil, Al-foil and ZnO:Al-covered glass as sacrificial substrates, {mu}c-Si:H and a-Si:H films were deposited by plasma-enhanced chemical vapor deposition (PECVD), and ESR powder samples have been prepared with corresponding procedures. Possible preparation-related metastability and instability effects have been investigated in terms of substrate dependence, HCl-etching and atmosphere exposure. A sequence of 'preparation - annealing - air-exposure - annealing' has been designed to investigate the metastability and instability effects. N{sub S} after post-preparation air exposure is higher than in the annealed states, especially for the highly crystalline {mu}c-Si:H material the discrepancy reached one order of magnitude. Low temperature ESR measurements at 40 K indicated that atmospheric exposure leads to a redistribution of the defect states which in turn influence the evaluated N{sub S}. In annealed conditions the samples tend to have lower N{sub S} presumably due

  15. Colloidal Nanocrystalline Semiconductor Materials as Photocatalysts for Environmental Protection of Architectural Stone

    Directory of Open Access Journals (Sweden)

    Francesca Petronella

    2017-01-01

    Full Text Available Rod-shaped TiO2 nanocrystals (TiO2 NRs, capped by oleic acid molecules (OLEA, were synthesized with controlled size, shape and surface chemistry by using colloidal routes. They were investigated for application as coating materials for preserving architectural stone of monumental and archaeological interest, in consideration of their self-cleaning and protection properties. For this purpose, two different deposition techniques, namely casting and dipping, were tested for the application of a nanocrystal dispersion on a defined stone type, as a relevant example of porous calcarenites, namely the Pietra Leccese, a building stone widely used in monuments and buildings of cultural and historic interest of the Apulia region (Italy. The physical properties of the stone surface were investigated before and after the treatment with the prepared nanostructured materials. In particular, colour, wettability, water transfer properties and stability of the coating were monitored as a function of time and of the application method. The self-cleaning properties of the TiO2 NRs coated surfaces were tested under simulated and real solar irradiation. The obtained results were discussed in the light of the specific surface chemistry and morphology of TiO2 NRs, demonstrating the effectiveness of TiO2 NRs as an active component in formulations for stone protection.

  16. Sensing Performance Study of SiC, a Wide Bandgap Semiconductor Material Platform for Surface Plasmon Resonance Sensor

    Directory of Open Access Journals (Sweden)

    Wei Du

    2015-01-01

    Full Text Available The sensing properties of a surface plasmon resonance (SPR based waveguide sensor on a wide bandgap semiconductor, silicon carbide (SiC, were studied. Compared to other waveguide sensors, the large bandgap energy of SiC material allows the sensor to operate in the visible and near infrared wavelength range, while the SPR effect by a thin gold film is expected to improve the sensitivity. The confinement factor of the sensor at various wavelengths of the incident light and refractive index of the analyte were investigated using an effective index method. Since the change of analyte type and concentration is reflected by the change of refractive index, the sensing performance can be evaluated by the shift of resonant wavelength from the confinement factor spectrum at different refractive index. The results show that the shift of resonant wavelength demonstrates linear characteristics. A sensitivity of 1928 nm/RIU (refractive index unit shift could be obtained from the refractive index of 1.338~1.348 which attracts research interests because most biological analytes are in this range.

  17. Fabrication of smart chemical sensors based on transition-doped-semiconductor nanostructure materials with µ-chips.

    Science.gov (United States)

    Rahman, Mohammed M; Khan, Sher Bahadar; Asiri, Abdullah M

    2014-01-01

    Transition metal doped semiconductor nanostructure materials (Sb2O3 doped ZnO microflowers, MFs) are deposited onto tiny µ-chip (surface area, ∼0.02217 cm(2)) to fabricate a smart chemical sensor for toxic ethanol in phosphate buffer solution (0.1 M PBS). The fabricated chemi-sensor is also exhibited higher sensitivity, large-dynamic concentration ranges, long-term stability, and improved electrochemical performances towards ethanol. The calibration plot is linear (r(2) = 0.9989) over the large ethanol concentration ranges (0.17 mM to 0.85 M). The sensitivity and detection limit is ∼5.845 µAcm(-2)mM(-1) and ∼0.11±0.02 mM (signal-to-noise ratio, at a SNR of 3) respectively. Here, doped MFs are prepared by a wet-chemical process using reducing agents in alkaline medium, which characterized by UV/vis., FT-IR, Raman, X-ray photoelectron spectroscopy (XPS), powder X-ray diffraction (XRD), and field-emission scanning electron microscopy (FE-SEM) etc. The fabricated ethanol chemical sensor using Sb2O3-ZnO MFs is simple, reliable, low-sample volume (<70.0 µL), easy of integration, high sensitivity, and excellent stability for the fabrication of efficient I-V sensors on μ-chips.

  18. Materials Design via Optimized Intramolecular Noncovalent Interactions for High-Performance Organic Semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Xiaojie; Liao, Qiaogan; Manley, Eric F.; Wu, Zishan; Wang, Yulun; Wang, Weida; Yang, Tingbin; Shin, Young-Eun; Cheng, Xing; Liang, Yongye; Chen, Lin X.; Baeg, Kang-Jun; Marks, Tobin J.; Guo, Xugang

    2016-03-15

    We report the design, synthesis, and implemention in semiconducting polymers of a novel head-to-head linkage containing the TRTOR (3-alkyl-3'-alkoxy-2,2'-bithiophene) donor subunit having a single strategically optimized, planarizing noncovalent S···O interaction. Diverse complementary thermal, optical, electrochemical, X-ray scattering, electrical, photovoltaic, and electron microscopic characterization techniques are applied to establish structure-property correlations in a TRTOR-based polymer series. In comparison to monomers having double S···O interactions, replacing one alkoxy substituent with a less electron-donating alkyl one yields TRTOR-based polymers with significantly depressed (0.2-0.3 eV) HOMOs. Furthermore, the weaker single S···O interaction and greater TRTOR steric encumberance enhances materials processability without sacrificing backbone planarity. From another perspective, TRTOR has comparable electronic properties to ring-fused 5Hdithieno[ 3,2-b:2',3'-d]pyran (DTP) subunits, but a centrosymmetric geometry which promotes a more compact and ordered structure than bulkier, axisymmetric DTP. Compared to monosubstituted TTOR (3-alkoxy-2,2'-bithiophene), alkylation at the TRTOR bithiophene 3-position enhances conjugation and polymer crystallinity with contracted π-π stacking. Grazing incidence wide-angle X-ray scattering (GIWAXS) data reveal that the greater steric hindrance and the weaker single S···O interaction are not detrimental to close packing and high crystallinity. As a proof of materials design, copolymerizing TRTOR with phthalimides yields copolymers with promising thin-film transistor mobility as high as 0.42 cm2/(V·s) and 6.3% power conversion efficiency in polymer solar cells, the highest of any phthalimide copolymers reported to date. The depressed TRTOR HOMOs imbue these polymers with substantially increased Ion/Ioff ratios and Voc’s versus analogous subunits with multiple electron donating

  19. Theoretical prediction of p-type transparent conductivity in Zn-doped TiO2.

    Science.gov (United States)

    Han, Xiaoping; Shao, Guosheng

    2013-06-28

    It is very difficult and yet extremely important to fill the wide technological gap in developing transparent conducting oxides (TCOs) that exhibit excellent p-type conducting characteristics. Here, on the basis of extensive first-principles calculations, we discover for the first time potentially promising p-type transparent conductivity in Zn-doped TiO2 under oxygen rich conditions. Efforts have been made to elaborate the effects of possible defects and their interaction with Zn doping on the p-type transparent conductivity. This work offers a fundamental road map for cost-effective development of p-type TCOs based on TiO2, which is a cheap and stable material system of large natural resources.

  20. Limits on the use of cobalt sulfide as anode of p-type dye-sensitized solar cells

    Science.gov (United States)

    Bonomo, Matteo; Congiu, Mirko; De Marco, Maria Letizia; Dowling, Denis P.; Di Carlo, Aldo; Graeff, Carlos F. O.; Dini, Danilo

    2017-06-01

    Thin films of cobalt sulfide (CoS) of thickness l  traditional platinized fluorine-doped indium oxide (Pt-FTO) due to the lower cost of the starting materials (Co salts) and the easier procedure of deposition onto large area substrates. The latter process was carried out via direct precipitation of CoS from aqueous solutions. The photoconversion efficiency (η) of the corresponding device was 0.07%. This value is about 35% less than the efficiency that is obtained with the analogous p-DSC employing the Pt-FTO anode (η  =  0.11). Unlike p-DSCs based on Pt-FTO anodes, the photoelectrochemical cells employing CoS electrodes showed that this anodic material was not able to sustain the photocurrent densities generated by P1-sensitized NiO at a given photopotential. Illumination of the p-DSCs with CoS anodes and P1-sensitized NiO cathodes actually induced the reverse bias of the photoelectrochemical cell with CoS behaving like a p-type semiconductor with no degeneracy. Dedicated to Professor Roberto Federici on the occasion of his retirement.

  1. Experiment requirements and implementation plan (Erip) for semiconductor materials growth in low-G environment

    Science.gov (United States)

    Crouch, R. K.; Fripp, A. L.; Debnam, W. J.; Clark, I. O.

    1983-01-01

    The MEA-2 A facility was used to test the effect of the low gravity environment on suppressing convective mixing in the growth of Pb(1-x)Sn(x)Te crystals. The need to eliminate convection, the furnace characteristics and operation that will be required for successful experimental implementation, and to the level that is presently known, the measured physical properties of the Pb(1-x)Sn(x)Te system were discussed. In addition, a brief background of the present and potential utilization of Pb(1-x)Sn(x)Te is given. Additional experiments are anticipated in future MEA-A, improved MEA and other dedicated materials processing in space flight apparatus.

  2. 25th anniversary article: materials for high-performance biodegradable semiconductor devices.

    Science.gov (United States)

    Hwang, Suk-Won; Park, Gayoung; Cheng, Huanyu; Song, Jun-Kyul; Kang, Seung-Kyun; Yin, Lan; Kim, Jae-Hwan; Omenetto, Fiorenzo G; Huang, Yonggang; Lee, Kyung-Mi; Rogers, John A

    2014-04-01

    We review recent progress in a class of silicon-based electronics that is capable of complete, controlled dissolution when immersed in water or bio-fluids. This type of technology, referred to in a broader sense as transient electronics, has potential applications in resorbable biomedical devices, eco-friendly electronics, environmental sensors, secure hardware systems and others. New results reported here include studies of the kinetics of hydrolysis of nanomembranes of single crystalline silicon in bio-fluids and aqueous solutions at various pH levels and temperatures. Evaluations of toxicity using live animal models and test coupons of transient electronic materials provide some evidence of their biocompatibility, thereby suggesting potential for use in bioresorbable electronic implants.

  3. Microstructure and magnetic behavior of Mn doped GeTe chalcogenide semiconductors based phase change materials

    Science.gov (United States)

    Adam, Adam Abdalla Elbashir; Cheng, Xiaomin; Abuelhassan, Hassan H.; Miao, Xiang Shui

    2017-06-01

    Phase-change materials (PCMs) are the most promising candidates to be used as an active media in the universal data storage and spintronic devices, due to their large differences in physical properties of the amorphous-crystalline phase transition behavior. In the present study, the microstructure, magnetic and electrical behaviors of Ge0.94Mn0.06Te thin film were investigated. The crystallographic structure of Ge0.94Mn0.06Te thin film was studied sing X-ray diffractometer (XRD) and High Resolution Transmission Electron Microscope (HR-TEM). The XRD pattern showed that the crystallization structure of the film was rhombohedral phase for GeTe with a preference (202) orientation. The HR-TEM image of the crystalline Ge0.94Mn0.06Te thin film demonstrated that, there were two large crystallites and small amorphous areas. The magnetization as a function of the magnetic field analyses of both amorphous and crystalline states showed the ferromagnetic hysteretic behaviors. Then, the hole carriers concentration of the film was measured and it found to be greater than 1021 cm-3 at room temperature. Moreover, the anomalous of Hall Effect (AHE) was clearly observed for the measuring temperatures 5, 10 and 50 K. The results demonstrated that the magnitude of AHE decreased when the temperature was increasing.

  4. Semiconductor diode laser material and devices with emission in visible region of the spectrum

    Science.gov (United States)

    Ladany, I.; Kressel, H.

    1975-01-01

    Two alloy systems, (AlGa)As and (InGa)P, were studied for their properties relevant to obtaining laser diode operation in the visible region of the spectrum. (AlGa)As was prepared by liquid-phase epitaxy (LPE) and (InGa)P was prepared both by vapor-phase epitaxy and by liquid-phase epitaxy. Various schemes for LPE growth were applied to (InGa)P, one of which was found to be capable of producing device material. All the InGaP device work was done using vapor-phase epitaxy. The most successful devices were fabricated in (AlGa)As using heterojunction structures. At room temperature, the large optical cavity design yielded devices lasing in the red (7000 A). Because of the relatively high threshold due to the basic band structure limitation in this alloy, practical laser diode operation is presently limited to about 7300 A. At liquid-nitrogen temperature, practical continuous-wave operation was obtained at a wavelength of 6500 to 6600 A, with power emission in excess of 50 mW. The lowest pulsed lasing wavelength is 6280 A. At 223 K, lasing was obtained at 6770 A, but with high threshold currents. The work dealing with CW operation at room temperature was successful with practical operation having been achieved to about 7800 A.

  5. Compound Semiconductor Radiation Detectors

    CERN Document Server

    Owens, Alan

    2012-01-01

    Although elemental semiconductors such as silicon and germanium are standard for energy dispersive spectroscopy in the laboratory, their use for an increasing range of applications is becoming marginalized by their physical limitations, namely the need for ancillary cooling, their modest stopping powers, and radiation intolerance. Compound semiconductors, on the other hand, encompass such a wide range of physical and electronic properties that they have become viable competitors in a number of applications. Compound Semiconductor Radiation Detectors is a consolidated source of information on all aspects of the use of compound semiconductors for radiation detection and measurement. Serious Competitors to Germanium and Silicon Radiation Detectors Wide-gap compound semiconductors offer the ability to operate in a range of hostile thermal and radiation environments while still maintaining sub-keV spectral resolution at X-ray wavelengths. Narrow-gap materials offer the potential of exceeding the spectral resolutio...

  6. A study of the photocatalytic effects of aqueous suspensions of platinized semiconductor materials on the reaction rates of candidate redox reactions

    Science.gov (United States)

    Miles, A. M.

    1982-01-01

    The effectiveness of powdered semiconductor materials in photocatalyzing candidate redox reactions was investigated. The rate of the photocatalyzed oxidation of cyanide at platinized TiO2 was studied. The extent of the cyanide reaction was followed directly using an electroanalytical method (i.e. differential pulse polarography). Experiments were performed in natural or artificial light. A comparison was made of kinetic data obtained for photocatalysis at platinized powders with rate data for nonplatinized powders.

  7. Semiconductor statistics

    CERN Document Server

    Blakemore, J S

    1987-01-01

    In-depth exploration of the implications of carrier populations and Fermi energies examines distribution of electrons in energy bands and impurity levels of semiconductors. Also: kinetics of semiconductors containing excess carriers, particularly in terms of trapping, excitation, and recombination.

  8. Density functional theory based tight binding study on theoretical prediction of low-density nanoporous phases ZnO semiconductor materials

    Science.gov (United States)

    Tuoc, Vu Ngoc; Doan Huan, Tran; Viet Minh, Nguyen; Thi Thao, Nguyen

    2016-06-01

    Polymorphs or phases - different inorganic solids structures of the same composition usually have widely differing properties and applications, thereby synthesizing or predicting new classes of polymorphs for a certain compound is of great significance and has been gaining considerable interest. Herein, we perform a density functional theory based tight binding (DFTB) study on theoretical prediction of several new phases series of II-VI semiconductor material ZnO nanoporous phases from their bottom-up building blocks. Among these, three phases are reported for the first time, which could greatly expand the family of II- VI compound nanoporous phases. We also show that all these generally can be categorized similarly to the aluminosilicate zeolites inorganic open-framework materials. The hollow cage structure of the corresponding building block ZnkOk (k= 9, 12, 16) is well preserved in all of them, which leads to their low-density nanoporous and high flexibility. Additionally the electronic wide-energy gap of the individual ZnkOk is also retained. Our study reveals that they are all semiconductor materials with a large band gap. Further, this study is likely to be the common for II-VI semiconductor compounds and will be helpful for extending their range of properties and applications.

  9. Piezo-phototronic effect on electroluminescence properties of p-type GaN thin films.

    Science.gov (United States)

    Hu, Youfan; Zhang, Yan; Lin, Long; Ding, Yong; Zhu, Guang; Wang, Zhong Lin

    2012-07-11

    We present that the electroluminescence (EL) properties of Mg-doped p-type GaN thin films can be tuned by the piezo-phototronic effect via adjusting the minority carrier injection efficiency at the metal-semiconductor (M-S) interface by strain induced polarization charges. The device is a metal-semiconductor-metal structure of indium tin oxide (ITO)-GaN-ITO. Under different straining conditions, the changing trend of the transport properties of GaN films can be divided into two types, corresponding to the different c-axis orientations of the films. An extreme value was observed for the integral EL intensity under certain applied strain due to the adjusted minority carrier injection efficiency by piezoelectric charges introduced at the M-S interface. The external quantum efficiency of the blue EL at 430 nm was changed by 5.84% under different straining conditions, which is 1 order of magnitude larger than the change of the green peak at 540 nm. The results indicate that the piezo-phototronic effect has a larger impact on the shallow acceptor states related EL process than on the one related to the deep acceptor states in p-type GaN films. This study has great significance on the practical applications of GaN in optoelectronic devices under a working environment where mechanical deformation is unavoidable such as for flexible/printable light emitting diodes.

  10. Infrared Transparent Spinel Films with p -Type Conductivity

    Energy Technology Data Exchange (ETDEWEB)

    Windisch, Charles F.; Exarhos, Gregory J.; Ferris, Kim F.; Engelhard, Mark H.; Stewart, Donald C.

    2001-11-29

    Spinel oxide films containing at least two transition metal cations were found to exhibit p-type conductivity with high optical transparency from the visible to wavelengths near 15 micrometers. Resistivities as low as 0.003 ohm-cm were measured on 100 nm thick rf sputter deposited films that contained nickel and cobalt. Optical spectra, Raman scattering and XPS measurements indicated the valency of nickel localized on octahedral sites within the spinel lattice determines these properties. Electronic band structure calculations corroborated the experimental results. A resistivity minimum was found at the composition NiCo2O4 deposited from aqueous or alcoholic solutions followed by subsequent annealing at 400 degrees C in air. Solution deposited films richer in nickel than this stoichiometry always were found to phase separate into nickel oxide and a spinel phase with concomitant loss in conductivity. However, the phase stability region could be extended to higher nickel contents when rf-sputter deposition techniques were used. Sputter deposited spinel films having a nickel to cobalt ratio less than 2 were found to exhibit the highest conductivity. Results suggest that the phase stability region for these materials can be extended through appropriate choice of deposition conditions. A possible mechanism that promotes high conductivity in this system is thought to be charge transfer between the resident di- and trivalent cations that may be assisted by the magnetic nature of the oxide film.

  11. P type porous silicon resistivity and carrier transport

    Energy Technology Data Exchange (ETDEWEB)

    Ménard, S., E-mail: samuel.menard@st.com [STMicroelectronics, 10, rue Thalès de Milet, 37071 Tours Cedex 2 (France); Fèvre, A. [STMicroelectronics, 10, rue Thalès de Milet, 37071 Tours Cedex 2 (France); Université François Rabelais de Tours, CNRS, CEA, INSA CVL, GREMAN UMR 7347, Tours (France); Billoué, J.; Gautier, G. [Université François Rabelais de Tours, CNRS, CEA, INSA CVL, GREMAN UMR 7347, Tours (France)

    2015-09-14

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

  12. Photoconduction spectroscopy of p-type GaSb films

    Energy Technology Data Exchange (ETDEWEB)

    Shura, M.W., E-mail: Megersa.Shura@live.nmmu.ac.za [Department of Physics, P.O. Box 77000, Nelson Mandela Metropolitan University, Port Elizabeth 6031 (South Africa); Wagener, V.; Botha, J.R.; Wagener, M.C. [Department of Physics, P.O. Box 77000, Nelson Mandela Metropolitan University, Port Elizabeth 6031 (South Africa)

    2012-05-15

    Excess carrier lifetimes (77 K) have been measured as function of the absorbed flux density in undoped p-type gallium antimonide films (GaSb/GaAs) using steady state photoconductivity measurements with the illumination wavelength of 1.1 {mu}m. Using the results from Hall effect measurements along with the relations describing the lifetimes of the excess minority carriers in the bulk of the films and at the surface, the theoretical values of the effective excess carrier lifetime in the materials were also calculated. Discrepancies between the experimental and theoretical results were described using a two-layer model, by considering the variation in the charge distribution within the layer due to the presence of surface states, as well as the band offset between the layer and the substrate. Theoretical modeling of the experimental result yields values of different parameters such as band bending at the surface, minimum value of Shockley-Read-Hall lifetime and maximum value of the surface recombination velocity.

  13. Semiconductor structure and recess formation etch technique

    Energy Technology Data Exchange (ETDEWEB)

    Lu, Bin; Sun, Min; Palacios, Tomas Apostol

    2017-02-14

    A semiconductor structure has a first layer that includes a first semiconductor material and a second layer that includes a second semiconductor material. The first semiconductor material is selectively etchable over the second semiconductor material using a first etching process. The first layer is disposed over the second layer. A recess is disposed at least in the first layer. Also described is a method of forming a semiconductor structure that includes a recess. The method includes etching a region in a first layer using a first etching process. The first layer includes a first semiconductor material. The first etching process stops at a second layer beneath the first layer. The second layer includes a second semiconductor material.

  14. Defects in semiconductors

    CERN Document Server

    Romano, Lucia; Jagadish, Chennupati

    2015-01-01

    This volume, number 91 in the Semiconductor and Semimetals series, focuses on defects in semiconductors. Defects in semiconductors help to explain several phenomena, from diffusion to getter, and to draw theories on materials' behavior in response to electrical or mechanical fields. The volume includes chapters focusing specifically on electron and proton irradiation of silicon, point defects in zinc oxide and gallium nitride, ion implantation defects and shallow junctions in silicon and germanium, and much more. It will help support students and scientists in their experimental and theoret

  15. Semiconductors bonds and bands

    CERN Document Server

    Ferry, David K

    2013-01-01

    As we settle into this second decade of the twenty-first century, it is evident that the advances in micro-electronics have truly revolutionized our day-to-day lifestyle. The technology is built upon semiconductors, materials in which the band gap has been engineered for special values suitable to the particular application. This book, written specifically for a one semester course for graduate students, provides a thorough understanding of the key solid state physics of semiconductors. It describes how quantum mechanics gives semiconductors unique properties that enabled the micro-electronics revolution, and sustain the ever-growing importance of this revolution.

  16. Enhanced thermopower and low thermal conductivity in p-type polycrystalline ZrTe5

    Science.gov (United States)

    Hooda, M. K.; Yadav, C. S.

    2017-07-01

    Thermoelectric properties of polycrystalline p-type ZrTe5 are reported in the temperature (T) range of 2-340 K. Thermoelectric power (S) is positive and reaches up to 458 μV/K at 340 K on increasing T. The value of Fermi energy 16 meV suggests a low carrier density of ≈9.5 × 1018 cm-3. A sharp anomaly in S data is observed at 38 K, which seems intrinsic to p-type ZrTe5. The thermal conductivity (κ) value is low (2 W/m K at T = 300 K) with major contribution from the lattice part. Electrical resistivity data show the metal to semiconductor transition at T ˜ 150 K and non-Arrhenius behavior in the semiconducting region. The figure of merit zT (0.026 at T = 300 K) is ˜63% higher than that of HfTe5 (0.016) and better than those of the conventional SnTe, p-type PbTe, and bipolar pristine ZrTe5 compounds.

  17. Time-resolved THz studies of carrier dynamics in semiconductors, superconductors, and strongly-correlated electron materials

    Energy Technology Data Exchange (ETDEWEB)

    Kaindl, Robert A.; Averitt, Richard D.

    2006-11-14

    Perhaps the most important aspect of contemporary condensed matter physics involves understanding strong Coulomb interactions between the large number of electrons in a solid. Electronic correlations lead to the emergence of new system properties, such as metal-insulator transitions, superconductivity, magneto-resistance, Bose-Einstein condensation, the formation of excitonic gases, or the integer and fractional Quantum Hall effects. The discovery of high-Tc superconductivity in particular was a watershed event, leading to dramatic experimental and theoretical advances in the field of correlated-electron systems. Such materials often exhibit competition between the charge, lattice, spin, and orbital degrees of freedom, whose cause-effect relationships are difficult to ascertain. Experimental insight into the properties of solids is traditionally obtained by time-averaged probes, which measure e.g., linear optical spectra, electrical conduction properties, or the occupied band structure in thermal equilibrium. Many novel physical properties arise from excitations out of the ground state into energetically higher states by thermal, optical, or electrical means. This leads to fundamental interactions between the system's constituents, such as electron-phonon and electron-electron interactions, which occur on ultrafast timescales. While these interactions underlie the physical properties of solids, they are often only indirectly inferred from time-averaged measurements. Time-resolved spectroscopy, consequently, is playing an ever increasing role to provide insight into light-matter interaction, microscopic processes, or cause-effect relationships that determine the physics of complex materials. In the past, experiments using visible and near-infrared femtosecond pulses have been extensively employed, e.g. to follow relaxation and dephasing processes in metals and semiconductors. However, many basic excitations in strongly-correlated electron systems and nanoscale

  18. Electronic structure of semiconductor-metal-semiconductor heterostructures

    Science.gov (United States)

    Masri, Pierre

    For the first time, we present in this article a microscopic self-consistent theory of the electronic structure of semiconductor-metal-semiconductor (SMS) heterostructures. This is done within the framework of a tight-binding approximation. We use a one-band model and a simplified two-band model to describe metal and semiconductor bulk bands, respectively. Results are given for a material-symmetrical and interface-assymetrical SMS structure: this involves the same semiconductors, but different interface polarities (anion- and cation-like interfaces). These results include metal-like states (built-in metal band) and metal-induced semiconductor-like states. The relevance of the charge neutrality condition to this feature and to the determination of the position of the SMS Fermi level is discussed. We also emphasize the confining role of interfaces, with respect to semiconductor-like states, within the semiconductor gap.

  19. Radiation effects in semiconductors

    CERN Document Server

    2011-01-01

    There is a need to understand and combat potential radiation damage problems in semiconductor devices and circuits. Written by international experts, this book explains the effects of radiation on semiconductor devices, radiation detectors, and electronic devices and components. These contributors explore emerging applications, detector technologies, circuit design techniques, new materials, and innovative system approaches. The text focuses on how the technology is being used rather than the mathematical foundations behind it. It covers CMOS radiation-tolerant circuit implementations, CMOS pr

  20. Variable temperature semiconductor film deposition

    Science.gov (United States)

    Li, Xiaonan; Sheldon, Peter

    1998-01-01

    A method of depositing a semiconductor material on a substrate. The method sequentially comprises (a) providing the semiconductor material in a depositable state such as a vapor for deposition on the substrate; (b) depositing the semiconductor material on the substrate while heating the substrate to a first temperature sufficient to cause the semiconductor material to form a first film layer having a first grain size; (c) continually depositing the semiconductor material on the substrate while cooling the substrate to a second temperature sufficient to cause the semiconductor material to form a second film layer deposited on the first film layer and having a second grain size smaller than the first grain size; and (d) raising the substrate temperature, while either continuing or not continuing to deposit semiconductor material to form a third film layer, to thereby anneal the film layers into a single layer having favorable efficiency characteristics in photovoltaic applications. A preferred semiconductor material is cadmium telluride deposited on a glass/tin oxide substrate already having thereon a film layer of cadmium sulfide.

  1. Comparison of ultra-high-resolution parallel-hole collimator materials based on the CdTe pixelated semiconductor SPECT system

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Young-Jin; Ryu, Hyun-Ju; Lee, Seung-Wan; Park, Su-Jin; Kim, Hee-Joung, E-mail: hjk1@yonsei.ac.kr

    2013-06-11

    Recently, many studies have sought to improve the sensitivity and spatial resolution of pixelated semiconductor detectors. Spatial resolution can be improved by using a pinhole or pixelated parallel-hole collimator with equal hole and pixel sizes. We compared a pinhole to a pixelated parallel-hole collimator and found that the pixelated parallel-hole collimator had higher sensitivity. Additionally, collimator materials with high absorption efficiency are often used because of their high spatial resolution. The purpose of this study was to compare the quality of images generated using a pixelated semiconductor single photon emission computed tomography (SPECT) system simulated with pixelated parallel-hole collimators of lead, tungsten, gold, and depleted uranium. We performed a simulation study of the PID 350 (Ajat Oy Ltd., Finland) CdTe pixelated semiconductor detector, which consists of small pixels (0.35×0.35 mm{sup 2}), using a Geant4 Application for Tomographic Emission (GATE) simulation. Sensitivities and spatial resolutions were measured for the four collimator materials. To evaluate overall image performance, a hot-rod phantom was designed using GATE simulation. The results showed that with lead, sensitivity was 4.25%, 6.53%, and 10.28% higher than with tungsten, gold, and depleted uranium, respectively. Spatial resolution using depleted uranium was 3.19%, 4.19%, and 8.01% better than that of gold, tungsten, and lead, respectively. Sensitivity and spatial resolution showed little difference among the four types of collimator materials tested. It was difficult to visually distinguish between the reconstructed images of the hot-rod phantom for different collimator materials. The results are promising for notable cost reductions in collimator manufacturing while avoiding impractical and rare materials.

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

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Shuai; Liu, Shu-Liang; Liu, Ling-Zhi; Liu, Yi-Chen [College of Physics, Qingdao University, Qingdao 266071 (China); Long, Yun-Ze, E-mail: yunze.long@163.com [College of Physics, Qingdao University, Qingdao 266071 (China); Key Laboratory of Photonics Materials and Technology in Universities of Shandong (Qingdao University), Qingdao 266071 (China); State Key Laboratory Cultivation Base of New Fiber Materials and Modern Textile, Qingdao University, Qingdao 266071 (China); Collaborative Innovation Center for Marine Biomass Fibers, Materials and Textiles of Shandong Province, Qingdao 266071 (China); Zhang, Hong-Di; Zhang, Jun-Cheng; Han, Wen-Peng [College of Physics, Qingdao University, Qingdao 266071 (China); Key Laboratory of Photonics Materials and Technology in Universities of Shandong (Qingdao University), Qingdao 266071 (China)

    2014-01-27

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

  3. A simple model to estimate the optimal doping of p - Type oxide superconductors

    Directory of Open Access Journals (Sweden)

    Adir Moysés Luiz

    2008-12-01

    Full Text Available Oxygen doping of superconductors is discussed. Doping high-Tc superconductors with oxygen seems to be more efficient than other doping procedures. Using the assumption of double valence fluctuations, we present a simple model to estimate the optimal doping of p-type oxide superconductors. The experimental values of oxygen content for optimal doping of the most important p-type oxide superconductors can be accounted for adequately using this simple model. We expect that our simple model will encourage further experimental and theoretical researches in superconducting materials.

  4. Quantum size effects in layered VX{sub 2} (X = S, Se) materials: Manifestation of metal to semimetal or semiconductor transition

    Energy Technology Data Exchange (ETDEWEB)

    Wasey, A. H. M. Abdul; Chakrabarty, Soubhik; Das, G. P., E-mail: msgpd@iacs.res.in [Department of Materials Science, Indian Association for the Cultivation of Science, Jadavpur, Kolkata-700032 (India)

    2015-02-14

    Most of the two dimensional (2D) transition metal dichalcogenides (TMDC) are nonmagnetic in pristine form. However, 2D pristine VX{sub 2} (X = S, Se, Te) materials are found to be ferromagnetic. Using spin polarized density functional theory (DFT) calculations, we have studied the electronic, magnetic, and surface properties of this class of materials in both trigonal prismatic H- and octahedral T-phase. Our calculations reveal that they exhibit materially different properties in those two polymorphs. Most importantly, detailed investigation of electronic structure explored the quantum size effect in H-phase of these materials thereby leading to metal to semimetal (H-VS{sub 2}) or semiconductor (H-VSe{sub 2}) transition when downsizing from bilayer to corresponding monolayer.

  5. Platinum nanoparticles on gallium nitride surfaces: effect of semiconductor doping on nanoparticle reactivity.

    Science.gov (United States)

    Schäfer, Susanne; Wyrzgol, Sonja A; Caterino, Roberta; Jentys, Andreas; Schoell, Sebastian J; Hävecker, Michael; Knop-Gericke, Axel; Lercher, Johannes A; Sharp, Ian D; Stutzmann, Martin

    2012-08-01

    Platinum nanoparticles supported on n- and p-type gallium nitride (GaN) are investigated as novel hybrid systems for the electronic control of catalytic activity via electronic interactions with the semiconductor support. In situ oxidation and reduction were studied with high pressure photoemission spectroscopy. The experiments revealed that the underlying wide-band-gap semiconductor has a large influence on the chemical composition and oxygen affinity of supported nanoparticles under X-ray irradiation. For as-deposited Pt cuboctahedra supported on n-type GaN, a higher fraction of oxidized surface atoms was observed compared to cuboctahedral particles supported on p-type GaN. Under an oxygen atmosphere, immediate oxidation was recorded for nanoparticles on n-type GaN, whereas little oxidation was observed for nanoparticles on p-type GaN. Together, these results indicate that changes in the Pt chemical state under X-ray irradiation depend on the type of GaN doping. The strong interaction between the nanoparticles and the support is consistent with charge transfer of X-ray photogenerated free carriers at the semiconductor-nanoparticle interface and suggests that GaN is a promising wide-band-gap support material for photocatalysis and electronic control of catalysis.

  6. Photoelectronic properties of semiconductors

    CERN Document Server

    Bube, Richard H

    1992-01-01

    The interaction between light and electrons in semiconductors forms the basis for many interesting and practically significant properties. This book examines the fundamental physics underlying this rich complexity of photoelectronic properties of semiconductors, and will familiarise the reader with the relatively simple models that are useful in describing these fundamentals. The basic physics is also illustrated with typical recent examples of experimental data and observations. Following introductory material on the basic concepts, the book moves on to consider a wide range of phenomena, including photoconductivity, recombination effects, photoelectronic methods of defect analysis, photoeffects at grain boundaries, amorphous semiconductors, photovoltaic effects and photoeffects in quantum wells and superlattices. The author is Professor of Materials Science and Electrical Engineering at Stanford University, and has taught this material for many years. He is an experienced author, his earlier books having fo...

  7. Studies of arsenic incorporation and P-type doping in epitaxial mercury cadmium telluride thin films grown by molecular beam epitaxy

    Science.gov (United States)

    Zandian, Majid

    Doped layer semiconductor structures provide possibilities for novel electronic devices. Growth of Hg1-xCdxTe by molecular beam epitaxy (MBE) allows precise control over the doping profile and position of heterojunctions as well as structural properties of this ternary alloy. Even though n-type doping using indium is well established, little is known about p-type doping in this material system by MBE. Several elements such as Ag, Au, Sb, Bi and P have been previously used, however high diffusion coefficient and amphoteric behavior of these atoms in HgCdTe has restricted their use in heterojunction devices where control over doping profiles and concentrations is needed. We investigated arsenic incorporation efficiency as a function of As 4 flux and growth temperature. The sticking coefficient of As is substantially higher at lower growth temperature compared to growth at 190°C. For samples grown at 170°C, the etch pit density (EPD) is higher compared to p-type As doped samples grown at 190°C. Higher EPD is associated with columnar twin defects observed in transmission electron microscopy (TEM) studies of low growth temperature samples. Growth at low temperature of 170°C causes Hg rich condition promoting twin formation. Therefore, growth of p-type layers doped with As at low temperatures require optimization of II/VI flux ratio to eliminate columnar twin defects. It is possible to incorporate As at normal MBE growth temperature of 190°C but very high flux of As has to used to overcome low sticking coefficient of As at these temperatures. We proposed a mechanism for the activation of As involving Hg vacancies (VHg··) where Te is moved to a Hg vacancy, leaving behind a Te vacancy, which is then filled by an As atom. The Te that is now on a Hg site (i.e., Te antisite) migrates to the surface and leaves the crystal.

  8. Zinc Alloys for the Fabrication of Semiconductor Devices

    Science.gov (United States)

    Ryu, Yungryel; Lee, Tae S.

    2009-01-01

    ZnBeO and ZnCdSeO alloys have been disclosed as materials for the improvement in performance, function, and capability of semiconductor devices. The alloys can be used alone or in combination to form active photonic layers that can emit over a range of wavelength values. Materials with both larger and smaller band gaps would allow for the fabrication of semiconductor heterostructures that have increased function in the ultraviolet (UV) region of the spectrum. ZnO is a wide band-gap material possessing good radiation-resistance properties. It is desirable to modify the energy band gap of ZnO to smaller values than that for ZnO and to larger values than that for ZnO for use in semiconductor devices. A material with band gap energy larger than that of ZnO would allow for the emission at shorter wavelengths for LED (light emitting diode) and LD (laser diode) devices, while a material with band gap energy smaller than that of ZnO would allow for emission at longer wavelengths for LED and LD devices. The amount of Be in the ZnBeO alloy system can be varied to increase the energy bandgap of ZnO to values larger than that of ZnO. The amount of Cd and Se in the ZnCdSeO alloy system can be varied to decrease the energy band gap of ZnO to values smaller than that of ZnO. Each alloy formed can be undoped or can be p-type doped using selected dopant elements, or can be n-type doped using selected dopant elements. The layers and structures formed with both the ZnBeO and ZnCdSeO semiconductor alloys - including undoped, p-type-doped, and n-type-doped types - can be used for fabricating photonic and electronic semiconductor devices for use in photonic and electronic applications. These devices can be used in LEDs, LDs, FETs (field effect transistors), PN junctions, PIN junctions, Schottky barrier diodes, UV detectors and transmitters, and transistors and transparent transistors. They also can be used in applications for lightemitting display, backlighting for displays, UV and

  9. «Green» Synthesis of Noble Metal Nanoparticles and CdS Semiconductor Nanocrystals Using Biological Material

    Directory of Open Access Journals (Sweden)

    Blume, Ya.B.

    2015-01-01

    Full Text Available The basic principles of synthesis of metal nanoparticles and semiconductor nanocrystals and its application prospects are considered. The relevance of the exploiting living systems and their components for the development of «green » synthesis technology for nano-objects with the unique properties and a wide range of applications is analyzed. The biotechnological synthesis of nanoparticles of silver, gold and bimetallic silver-gold nanoparticles using plant extracts of Magnolia denudata, M. stellata, Camellia sinensis var. sinensis, C. sinensis var. assamica, Orthosiphon stamineus and Hypericum perforatum is described. The results of cadmium sulfide fluorescent semiconductor nanocrystal synthesis using bacteria Escherichia coli, basidiomycete Pleurotus ostreatus and plant Linaria maroccana are reported. Morphological and optical characteristics of the synthesized nanoparticles are presented.

  10. p-Type Semiconducting Nickel Oxide as an Efficiency-Enhancing Anode Interfacial Layer in Polymer Bulk-Heterojunction Solar Cells

    National Research Council Canada - National Science Library

    Michael D. Irwin; D. Bruce Buchholz; Alexander W. Hains; Robert P. H. Chang; Tobin J. Marks

    2008-01-01

    To minimize interfacial power losses, thin (5-80 nm) layers of NiO, a p-type oxide semiconductor, are inserted between the active organic layer, poly(3-hexylthiophene) (P3HT) + [6,6]-phenyl-C₆₁...

  11. New Material Transistor with Record-High Field-Effect Mobility among Wide-Band-Gap Semiconductors.

    Science.gov (United States)

    Shih, Cheng Wei; Chin, Albert

    2016-08-03

    At an ultrathin 5 nm, we report a new high-mobility tin oxide (SnO2) metal-oxide-semiconductor field-effect transistor (MOSFET) exhibiting extremely high field-effect mobility values of 279 and 255 cm(2)/V-s at 145 and 205 °C, respectively. These values are the highest reported mobility values among all wide-band-gap semiconductors of GaN, SiC, and metal-oxide MOSFETs, and they also exceed those of silicon devices at the aforementioned elevated temperatures. For the first time among existing semiconductor transistors, a new device physical phenomenon of a higher mobility value was measured at 45-205 °C than at 25 °C, which is due to the lower optical phonon scattering by the large SnO2 phonon energy. Moreover, the high on-current/off-current of 4 × 10(6) and the positive threshold voltage of 0.14 V at 25 °C are significantly better than those of a graphene transistor. This wide-band-gap SnO2 MOSFET exhibits high mobility in a 25-205 °C temperature range, a wide operating voltage of 1.5-20 V, and the ability to form on an amorphous substrate, rendering it an ideal candidate for multifunctional low-power integrated circuit (IC), display, and brain-mimicking three-dimensional IC applications.

  12. Synthesis of p-type and n-type nickel ferrites and associated electrical properties

    Energy Technology Data Exchange (ETDEWEB)

    Šutka, Andris, E-mail: andris.sutka@rtu.lv [Faculty of Material Science and Applied Chemistry, Riga Technical University, Paula Valdena 3, Riga, LV-1048 (Latvia); Institute of Physics, University of Tartu, Ravila 14c, 50411, 51014 Tartu (Estonia); Pärna, Rainer [Institute of Physics, University of Tartu, Ravila 14c, 50411, 51014 Tartu (Estonia); Estonian Nanotechnology Competence Centre, Ravila 14c, 50411, 51014 Tartu (Estonia); Käämbre, Tanel [Institute of Physics, University of Tartu, Ravila 14c, 50411, 51014 Tartu (Estonia); Kisand, Vambola [Institute of Physics, University of Tartu, Ravila 14c, 50411, 51014 Tartu (Estonia); Estonian Nanotechnology Competence Centre, Ravila 14c, 50411, 51014 Tartu (Estonia)

    2015-01-01

    We used sol–gel auto combustion to synthesize nickel ferrites of p-type and n-type conductivity by controlling the relative amounts of nickel and iron during synthesis. The obtained samples have been characterized by XRD, FE-SEM, electrical measurements and XPS. We observe huge differences in the effect of grain size on the electrical resistivity between the p-type and the n-type material when the grain size increases from nano to micro scale during annealing at temperatures from 900 {sup o}C to 1300 {sup o}C. The observed resistivity decrease (due to grain size) is four orders of magnitude in the n-type nickel ferrite, whereas the p-type material remains virtually unaffected. We rationalize this drastic difference to stem from a reverse contrast of the surface (grain shell) versus bulk (grain core) conductivity between p- and n-type ferrite. With the grain shells in p-type the easier charge carrier path the effect of scatter at grain boundaries is accordingly diminished, whereas in the n-type charge transport properties are controlled by (the number of) grain boundaries in a conduction path.

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

    Science.gov (United States)

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

    2013-03-01

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

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

    Science.gov (United States)

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

    2015-04-29

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

  15. NCD Diamond Semiconductor System for Advanced Power Electronics Systems Integration : CRADA report

    Energy Technology Data Exchange (ETDEWEB)

    Sumant, Anirudha [AKHAN Semiconductor, Inc., Hoffman Estates, IL (United States)

    2016-07-22

    The integration of 2D materials such as molybdenum disulphide (MoS2) with diamond (3D) was achieved by forming an heterojunction between these two materials and its electrical performance was studied experimentally. The device charactertics did show good rectifying nature when p-type single crystal diamond was integrated with n-type MoS2. These results are very encouraging indicating possible applications in semiconductor electronics, however further studies are required for a detailed understanding of the transport phenomena at the MoS2/diamond interface.

  16. Electrodes for Semiconductor Gas Sensors.

    Science.gov (United States)

    Lee, Sung Pil

    2017-03-25

    The electrodes of semiconductor gas sensors are important in characterizing sensors based on their sensitivity, selectivity, reversibility, response time, and long-term stability. The types and materials of electrodes used for semiconductor gas sensors are analyzed. In addition, the effect of interfacial zones and surface states of electrode-semiconductor interfaces on their characteristics is studied. This study describes that the gas interaction mechanism of the electrode-semiconductor interfaces should take into account the interfacial zone, surface states, image force, and tunneling effect.

  17. Semiconductor photocatalysis principles and applications

    CERN Document Server

    Kisch, Horst

    2014-01-01

    Focusing on the basic principles of semiconductor photocatalysis, this book also gives a brief introduction to photochemistry, photoelectrochemistry, and homogeneous photocatalysis. In addition, the author - one of the leading authorities in the field - presents important environmental and practical aspects. A valuable, one-stop source for all chemists, material scientists, and physicists working in this area, as well as novice researchers entering semiconductor photocatalysis.

  18. Characterization of Structural Defects in Wide Band-Gap Compound Materials for Semiconductor and Opto-Electronic Applications

    Science.gov (United States)

    Goue, Ouloide Yannick

    Single crystals of binary and ternary compounds are touted to replace silicon for specialized applications in the semiconductor industry. However, the relative high density of structural defects in those crystals has hampered the performance of devices built on them. In order to enhance the performance of those devices, structurally perfect single crystals must be grown. The aim of this thesis is to investigate the interplay between crystal growth process and crystal quality as well as structural defect types and transport property. To this end, the thesis is divided into two parts. The first part provides a general review of the theory of crystal growth (chapter I), an introduction to the materials being investigated (chapter II and III) and the characterization techniques being used (chapter IV). • In chapter I, a brief description of the theory of crystal growth is provided with an eye towards the driving force behind crystal nucleation and growth along with the kinetic factors affecting crystal growth. The case of crystal growth of silicon carbide (SiC) by physical vapor transport (PVT) and chemical vapor deposition (CVD) is discussed. The Bridgman, travelling heater method (THM) and physical transport growth of cadmium zinc telluride (CZT) is also treated. In chapters II and III, we introduce the compound materials being investigated in this study. While a description of their crystal structure and properties is provided, the issues associated with their growth are discussed. In chapter IV, a description of the characterization techniques used in these studies is presented. These techniques are synchrotron X-ray topography (SXRT), transmission electron microscopy, transmission infrared microscopy (TIM), micro-Raman spectroscopy (muRS) and light microscopy. Extensive treatment of SXRT technique is also provided. In the second part, the experimental results obtained in the course of these studies are presented and discussed. These results are divided into

  19. Anisotropic electron-transfer mobilities in diethynyl-indenofluorene-dione crystals as high-performance n-type organic semiconductor materials: remarkable enhancement by varying substituents.

    Science.gov (United States)

    Zhang, Xiao-Yu; Huang, Jin-Dou; Yu, Juan-Juan; Li, Peng; Zhang, Wei-Ping; Frauenheim, Thoma

    2015-10-14

    In this study, the electron-transfer properties of alkynylated indenofluorene-diones with various substituents (SiMe3, SiPr3, and SiPh3) that function as n-type organic semiconductors were comparatively investigated at the first-principles DFT level based on the Marcus-Hush theory. The reorganization energies are calculated by the adiabatic potential-energy surface method, and the coupling terms are evaluated through a direct adiabatic model. The maximum value of the electron-transfer mobility of SiPr3 is 0.485 cm(2) V(-1) s(-1), which appears at the orientation angle of the conducting channel on the reference plane a-b near to 172°/352°. The predicted maximum electron mobility value of SiPr3 is nearly 26 times larger than that of SiPh3. This may be attributed to the largest number of intermolecular π-π interactions. In addition, the mobilities in all three crystals show remarkable anisotropic behavior. The calculated results indicate that SiPr3 could be an ideal candidate as a high-performance n-type organic semiconductor material. Our investigations not only give us an opportunity to completely understand the charge transport mechanisms, but also provide guidelines for designing materials for electronic applications.

  20. Semiconductors for organic transistors

    Directory of Open Access Journals (Sweden)

    Antonio Facchetti

    2007-03-01

    Full Text Available Organic molecules/polymers with a π-conjugated (heteroaromatic backbone are capable of transporting charge and interact efficiently with light. Therefore, these systems can act as semiconductors in opto-electronic devices similar to inorganic materials. However, organic chemistry offers tools for tailoring materials' functional properties via modifications of the molecular/monomeric units, opening new possibilities for inexpensive device manufacturing. This article reviews the fundamental aspects behind the structural design/realization of p- (hole transporting and n-channel (electron-transporting semiconductors for organic field-effect transistors (OFETs. An introduction to OFET principles and history, as well as of the state-of-the-art organic semiconductor structure and performance of OFETs is provided.

  1. Hydrogen in semiconductors II

    CERN Document Server

    Nickel, Norbert H; Weber, Eicke R; Nickel, Norbert H

    1999-01-01

    Since its inception in 1966, the series of numbered volumes known as Semiconductors and Semimetals has distinguished itself through the careful selection of well-known authors, editors, and contributors. The "Willardson and Beer" Series, as it is widely known, has succeeded in publishing numerous landmark volumes and chapters. Not only did many of these volumes make an impact at the time of their publication, but they continue to be well-cited years after their original release. Recently, Professor Eicke R. Weber of the University of California at Berkeley joined as a co-editor of the series. Professor Weber, a well-known expert in the field of semiconductor materials, will further contribute to continuing the series' tradition of publishing timely, highly relevant, and long-impacting volumes. Some of the recent volumes, such as Hydrogen in Semiconductors, Imperfections in III/V Materials, Epitaxial Microstructures, High-Speed Heterostructure Devices, Oxygen in Silicon, and others promise that this tradition ...

  2. Synthesis and characterization of p-type boron-doped IIb diamond large single crystals

    Institute of Scientific and Technical Information of China (English)

    Li Shang-Sheng; Ma Hong-An; Li Xiao-Lei; Su Tai-Chao; Huang Guo-Feng; Li Yong; Jia Xiao-Peng

    2011-01-01

    High-quality p-type boron-doped II0b diamond large single crystals are successfully synthesized by the temperature gradient method in a china-type cubic anvil high-pressure apparatus at about 5.5 GPa and 1600 K. The morphologies and surface textures of the synthetic diamond crystals with different boron additive quantities are characterized by using an optical microscope and a scanning electron microscope respectively. The impurities of nitrogen and boron in diamonds are detected by micro Fourier transform infrared technique. The electrical properties including resistivities, Hall coefficients, Hall mobilities and carrier densities of the synthesized samples are measured by a four-point probe and the Hall effect method. The results show that large p-type boron-doped diamond single crystals with few nitrogen impurities have been synthesized. With the increase of quantity of additive boron, some high-index crystal faces such as {113} gradually disappear, and some stripes and triangle pits occur on the crystal surface. This work is helpful for the further research and application of boron-doped semiconductor diamond.

  3. Atomic layer deposition of undoped TiO2 exhibiting p-type conductivity.

    Science.gov (United States)

    Iancu, Andrei T; Logar, Manca; Park, Joonsuk; Prinz, Fritz B

    2015-03-11

    With prominent photocatalytic applications and widespread use in semiconductor devices, TiO2 is one of the most popular metal oxides. However, despite its popularity, it has yet to achieve its full potential due to a lack of effective methods for achieving p-type conductivity. Here, we show that undoped p-type TiO2 films can be fabricated by atomic layer deposition (ALD) and that their electrical properties can be controlled across a wide range using proper postprocessing anneals in various ambient environments. Hole mobilities larger than 400 cm(2)/(V·s) are accessible superseding the use of extrinsic doping, which generally produces orders of magnitude smaller values. Through a combination of analyses and experiments, we provide evidence that this behavior is primarily due to an excess of oxygen in the films. This discovery enables entirely new categories of TiO2 devices and applications, and unlocks the potential to improve existing ones. TiO2 homojunction diodes fabricated completely by ALD are developed as a demonstration of the utility of these techniques and shown to exhibit useful rectifying characteristics even with minimal processing refinement.

  4. Semiconductor spintronics

    CERN Document Server

    Xia, Jianbai; Chang, Kai

    2012-01-01

    Semiconductor Spintronics, as an emerging research discipline and an important advanced field in physics, has developed quickly and obtained fruitful results in recent decades. This volume is the first monograph summarizing the physical foundation and the experimental results obtained in this field. With the culmination of the authors' extensive working experiences, this book presents the developing history of semiconductor spintronics, its basic concepts and theories, experimental results, and the prospected future development. This unique book intends to provide a systematic and modern foundation for semiconductor spintronics aimed at researchers, professors, post-doctorates, and graduate students, and to help them master the overall knowledge of spintronics.

  5. 氧化锌材料p型掺杂研究进展%Recent Research on p-type Doping of ZnO

    Institute of Scientific and Technical Information of China (English)

    谭蜜; 张红; 李万俊; 秦国平; 阮海波; 孔春阳

    2016-01-01

    氧化锌(ZnO)是 II-VI 族直接带隙化合物半导体材料,室温下禁带宽度为3.37 eV,激子束缚能高达60 meV,是制造蓝紫外发光、探测以及激光器件的理想材料。高质量 n 型和 p 型 ZnO 以及同质 p-n 结的制备是实现器件化的关键。目前,n 型 ZnO 的制备技术已趋于成熟,但高质量稳定的 p 型 ZnO 的缺乏已成为制约其器件化的瓶颈。在过去的十余年里,通过国内外科研工作者的不懈努力,在理论和实验上都取得了显著的成果。本文主要概述了 ZnO 材料的 p 型掺杂、p 型导电机制以及 p-ZnO 基光电器件的研究进展,同时初步探索了 ZnO 材料 p 型导电稳定性问题。%Zinc oxide (ZnO),a typical direct wide bandgap (3.37 eV)semiconductor,has attracted an increasing interest tothe optoelectronics field.Its large exciton binding energy of 60 meV endows it with high radiative recom-bination efficiency,a unique advantage in light emitting and lasing devices.The fabrications of high quality n-and p-type ZnO as well as p-n junction are the key steps to realize these applications.although the techniques of fabri-cated n-type ZnO has been well developed,the reliable p type doping of the material remains a major challenge to optoelectronic applications,despitethe fact that p-doping of ZnO has been improved and that marked results in ex-periment and theory have been achieved during the past ten years.In this review,we examined the recent research progress in p-type doping of ZnO,including the p-type performance,the mechanism of p-type conduction,and p-ZnO based photoelectric devices,and so on.Moreover,based on the challenges of the current researches,we sum-marized the factors that may affect the p-type doping,especially the stability of p-type ZnO materials.

  6. Sol-gel derived precursors to Group 14 semiconductor nanocrystals - Convenient materials for enabling nanocrystal-based applications

    Energy Technology Data Exchange (ETDEWEB)

    Veinot, Jonathan G C; Henderson, Eric J; Hessel, Colin M, E-mail: jveinot@ualberta.ca [Department of Chemistry, University of Alberta, Edmonton, Alberta (Canada)

    2009-11-15

    Semiconductor nanocrystals are intriguing because of their electronic, optical, and chemical characteristics. Silicon nanocrystals (Si-NCs) of sub-5 nm dimension are of particular interest due to their intense photoluminescent response and the promise of linking silicon photonics and electronics. Other related nanomaterials of technological importance include SiC and Ge. The following contribution describes key experimental findings pertaining to synthetic methodology, investigation of nanodomain formation and growth, as determined by X-ray powder diffraction (XRD) and photoluminescence (PL) spectroscopy for a series of sol-gel derived prepolymers suitable for preparing Group 14 based nanocrystal containing composites.

  7. Sol-gel derived precursors to Group 14 semiconductor nanocrystals - Convenient materials for enabling nanocrystal-based applications

    Science.gov (United States)

    Veinot, Jonathan G. C.; Henderson, Eric J.; Hessel, Colin M.

    2009-11-01

    Semiconductor nanocrystals are intriguing because of their electronic, optical, and chemical characteristics. Silicon nanocrystals (Si-NCs) of sub-5 nm dimension are of particular interest due to their intense photoluminescent response and the promise of linking silicon photonics and electronics. Other related nanomaterials of technological importance include SiC and Ge. The following contribution describes key experimental findings pertaining to synthetic methodology, investigation of nanodomain formation and growth, as determined by X-ray powder diffraction (XRD) and photoluminescence (PL) spectroscopy for a series of sol-gel derived prepolymers suitable for preparing Group 14 based nanocrystal containing composites.

  8. Nanoparticulate dye-semiconductor hybrid materials formed by electrochemical self-assembly as electrodes in photoelectrochemical cells

    Energy Technology Data Exchange (ETDEWEB)

    Nonomura, Kazuteru; Loewenstein, Thomas; Schlettwein, Derck [Inst. fuer Angewandte Physik, Justus-Liebig-Univ. Giessen (Germany); Michaelis, Esther; Woehrle, Dieter [Inst. fuer Organische und Makromolekulare Chemie, Univ. Bremen (Germany); Kunze, Peter; Schiek, Manuela; Al-Shamery, Katharina; Yoshida, Tsukasa [Physikalische Chemie, Univ. Oldenburg (Germany); Reemts, Jens; Kittel, Achim; Parisi, Juergen [Abt. Energie- und Halbleiterforschung, Univ. Oldenburg (Germany); Iwaya, Mirian Yoshie [Environmental and Renewable Energy Systems, Gifu Univ. (Japan); Wark, Michael [Inst. fuer Physikalische Chemie und Elektrochemie, Univ. Hannover (Germany); Rathousky, Jiri [J. Heyrovsky Inst. of Physical Chemistry, Academy of Sciences of the Czech Republic, Prague (Czech Republic)

    2009-07-15

    Dye-sensitized zinc oxide thin films were prepared, characterized and optimized for applications as photoelectrochemically active electrodes. Conditions were established under which crystalline thin films of ZnO with a porous texture were formed by electrochemically induced crystallization controlled by structure-directing agents (SDA). Dye molecules were adsorbed either directly as SDA during this preparation step or, preferably, following desorption of a SDA. The external quantum efficiency (IPCE) could thereby be increased significantly. Particular emphasis was laid on dye molecules that absorb in the red part of the visible spectrum. Model experiments under ultrahigh vacuum (UHV) conditions with dye molecules adsorbed on defined crystal planes of single crystals aimed at a deeper understanding of the coupling of the chromophore electronic {pi}-system within molecular aggregates and to the semiconductor surface. Detailed photoelectrochemical kinetic measurements were used to characterize and optimize the electrochemically prepared dye-sensitized ZnO films. Parallel electrical characterization in vacuum served to distinguish between contributions of charge transport within the ZnO semiconductor matrix and the ions of the electrolyte in the pore system of the electrode. (orig.)

  9. Radiation damage studies of multi-guard ring p-type bulk diodes

    CERN Document Server

    Bortoletto, D; Günther, M; Grim, G P; Lander, R L; Willard, S; Li, Z

    1999-01-01

    Several diodes with different multi-guard ring structures were fabricated from 10 k OMEGA cm p-type bulk material. Studies on the performance of such devices are presented here. They include the measurement of the leakage current, breakdown voltage and charge collection efficiency before and after 2x10 sup 1 sup 4 p/cm sup 2 irradiation with 63.3 MeV kinetic protons. (author)

  10. Semiconductor heterojunctions

    CERN Document Server

    Sharma, B L

    1974-01-01

    Semiconductor Heterojunctions investigates various aspects of semiconductor heterojunctions. Topics covered include the theory of heterojunctions and their energy band profiles, electrical and optoelectronic properties, and methods of preparation. A number of heterojunction devices are also considered, from photovoltaic converters to photodiodes, transistors, and injection lasers.Comprised of eight chapters, this volume begins with an overview of the theory of heterojunctions and a discussion on abrupt isotype and anisotype heterojunctions, along with graded heterojunctions. The reader is then

  11. THERMOELECTRIC PROPERTIES OF HOT-PRESSED p-TYPE Mg2Si0.3Sn0.7 SOLID SOLUTION

    Directory of Open Access Journals (Sweden)

    G. N. Isachenko

    2014-05-01

    Full Text Available It is shown that thermoelectric energy conversion which gives the possibility for utilizing a low potential heat is one of the ways for adoption of energy-saving technologies; and semiconductor materials with p-type and n-type conductivities having high thermoelectric figure of merit are necessary for operation of thermoelectric generators. The paper deals with possibility of usage of the p-Mg2Si0.3Sn0.7 solid solution (with a nanostructured modification as a couple for the well studied thermoelectric material based on n-Mg2Si-Mg2Sn. A technological scheme for fabrication of heavily doped Mg2Si0.3Sn0.7 solid solution of p-type by hot pressing from nanopowder is developed. The given technology has made it possible to reduce duration of a homogeneous material fabrication and has improved its physical and chemical properties. The samples were made by three ways: direct fusion for polycrystals fabrication; hot pressing from microparticles; nanostructuring, i.e. hot pressing from nanoparticles. By X-ray diffraction it is shown that sizes of structural elements in the fabricated samples are about 40 nm. The probe technique is used for measurement of electric conductivity and Seebeck coefficient. The stationary absolute method is used for measurement of thermal conductivity. Thermoelectric figure of merit is defined by measured values of kinetic coefficients in the temperatures range of 77 – 800 K. It was demonstrated, that electric conductivity, Seebeck coefficient and the power factor do not depend practically on a way of solid solution preparation. Thermal conductivity of samples pressed from nanoparticles has appeared to be higher, than of samples, obtained by direct fusion; i.e. in this case nanostructuring has not led to increase of thermoelectric figure of merit. The conclusion is drawn, that polycrystalline semiconductor Mg2Si0.3Sn0.7 can be used as a p-branch for a thermoelectric generator though nanostructuring has not led to the figure of

  12. Methods of producing free-standing semiconductors using sacrificial buffer layers and recyclable substrates

    Science.gov (United States)

    Ptak, Aaron Joseph; Lin, Yong; Norman, Andrew; Alberi, Kirstin

    2015-05-26

    A method of producing semiconductor materials and devices that incorporate the semiconductor materials are provided. In particular, a method is provided of producing a semiconductor material, such as a III-V semiconductor, on a spinel substrate using a sacrificial buffer layer, and devices such as photovoltaic cells that incorporate the semiconductor materials. The sacrificial buffer material and semiconductor materials may be deposited using lattice-matching epitaxy or coincident site lattice-matching epitaxy, resulting in a close degree of lattice matching between the substrate material and deposited material for a wide variety of material compositions. The sacrificial buffer layer may be dissolved using an epitaxial liftoff technique in order to separate the semiconductor device from the spinel substrate, and the spinel substrate may be reused in the subsequent fabrication of other semiconductor devices. The low-defect density semiconductor materials produced using this method result in the enhanced performance of the semiconductor devices that incorporate the semiconductor materials.

  13. Semiconductor assisted metal deposition for nanolithography applications

    Science.gov (United States)

    Rajh, Tijana; Meshkov, Natalia; Nedelijkovic, Jovan M.; Skubal, Laura R.; Tiede, David M.; Thurnauer, Marion

    2001-01-01

    An article of manufacture and method of forming nanoparticle sized material components. A semiconductor oxide substrate includes nanoparticles of semiconductor oxide. A modifier is deposited onto the nanoparticles, and a source of metal ions are deposited in association with the semiconductor and the modifier, the modifier enabling electronic hole scavenging and chelation of the metal ions. The metal ions and modifier are illuminated to cause reduction of the metal ions to metal onto the semiconductor nanoparticles.

  14. p-Type Quasi-Mono Silicon Solar Cell Fabricated by Ion Implantation

    Directory of Open Access Journals (Sweden)

    Chien-Ming Lee

    2013-01-01

    Full Text Available The p-type quasi-mono wafer is a novel type of silicon material that is processed using a seed directional solidification technique. This material is a promising alternative to traditional high-cost Czochralski (CZ and float-zone (FZ material. Here, we evaluate the application of an advanced solar cell process featuring a novel method of ion implantation on p-type quasi-mono silicon wafer. The ion implantation process has simplified the normal industrial process flow by eliminating two process steps: the removal of phosphosilicate glass (PSG and the junction isolation process that is required after the conventional thermal POCl3 diffusion process. Moreover, the good passivation performance of the ion implantation process improves Voc. Our results show that, after metallization and cofiring, an average cell efficiency of 18.55% can be achieved using 156 × 156 mm p-type quasi-mono silicon wafer. Furthermore, the absolute cell efficiency obtained using this method is 0.47% higher than that for the traditional POCl3 diffusion process.

  15. Optical processes in semiconductors

    CERN Document Server

    Pankove, Jacques I

    1975-01-01

    Based on a series of lectures at Berkeley, 1968-1969, this is the first book to deal comprehensively with all of the phenomena involving light in semiconductors. The author has combined, for the graduate student and researcher, a great variety of source material, journal research, and many years of experimental research, adding new insights published for the first time in this book.Coverage includes energy states in semiconductors and their perturbation by external parameters, absorption, relationships between optical constants, spectroscopy, radiative transitions, nonradiative recombination

  16. Advances in semiconductor lasers

    CERN Document Server

    Coleman, James J; Jagadish, Chennupati

    2012-01-01

    Semiconductors and Semimetals has distinguished itself through the careful selection of well-known authors, editors, and contributors. Originally widely known as the ""Willardson and Beer"" Series, it has succeeded in publishing numerous landmark volumes and chapters. The series publishes timely, highly relevant volumes intended for long-term impact and reflecting the truly interdisciplinary nature of the field. The volumes in Semiconductors and Semimetals have been and will continue to be of great interest to physicists, chemists, materials scientists, and device engineers in academia, scien

  17. Growth of nitrogen-doped p-type ZnO thin films prepared by atomic layer epitaxy

    Institute of Scientific and Technical Information of China (English)

    LEE Chongmu; LIM Jongmin; PARK Suyoung; KIM Hyounwoo

    2006-01-01

    Nitrogen-doped, p-type ZnO thin films were grown successfully on sapphire (0001) substrates by using atomic layer epitaxy (ALE). Zn(C2H5)2[Diethylzinc,DEZn], H2O and NH3 were used as a zinc precursor, an oxidant and a doping source gas, respectively. The lowest electrical resistivity of the p-type ZnO films grown by ALE and annealed at 1000 ℃ in an oxygen atmosphere for 1 h was 18.3 Ω·m with a hole concentration of 3.71×1017cm-3 . Low temperature-photoluminescence analysis and time-dependent Hall measurement results support that the nitrogen-doped ZnO after annealing is ap-type semiconductor.

  18. Electronic structure of ferromagnetic semiconductor material on the monoclinic and rhombohedral ordered double perovskites La{sub 2}FeCoO{sub 6}

    Energy Technology Data Exchange (ETDEWEB)

    Fuh, Huei-Ru; Chang, Ching-Ray [Department of Physics, National Taiwan University, Taipei 106, Taiwan (China); Graduate Institute of Applied Physics, National Taiwan University, Taipei 106, Taiwan (China); Weng, Ke-Chuan [Department of Physics, National Taiwan University, Taipei 106, Taiwan (China); Wang, Yin-Kuo, E-mail: kant@ntnu.edu.tw [Center for General Education and Department of Physics, National Taiwan Normal University, Taipei 106, Taiwan (China)

    2015-05-07

    Double perovskite La{sub 2}FeCoO{sub 6} with monoclinic structure and rhombohedra structure show as ferromagnetic semiconductor based on density functional theory calculation. The ferromagnetic semiconductor state can be well explained by the superexchange interaction. Moreover, the ferromagnetic semiconductor state remains under the generalized gradient approximation (GGA) and GGA plus onsite Coulomb interaction calculation.

  19. A survey of ohmic contacts to III-V compound semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    Baca, A.G.; Zolper, J.C.; Briggs, R.D. [Sandia National Labs., Albuquerque, NM (United States); Ren, F. [Lucent Technologies, Murray Hill, NJ (United States); Pearton, S.J. [Univ. of Florida, Gainesville, FL (United States)

    1997-04-01

    A survey of ohmic contact materials and properties to GaAs, InP, GaN will be presented along with critical issues pertaining to each semiconductor material. Au-based alloys (e.g., GeAuNi for n-type GaAs) are the most commonly used contacts for GaAs and InP materials for both n- and p-type contacts due to the excellent contact resistivity, reliability, and usefulness over a wide range of doping levels. Research into new contacting schemes for these materials has focused on addressing limitations of the conventional Au-alloys in thermal stability, propensity for spiking, poor edge definition, and new approaches for a non-alloyed contact. The alternative contacts to GaAs and InP include alloys with higher temperature stability, contacts based on solid phase regrowth, and contacts that react with the substrate to form lower bandgap semiconductors alloys at the interface. A new area of contact studies is for the wide bandgap group III-Nitride materials. At present, low resistivity ohmic contact to p-type GaN has not been obtained primarily due to the large acceptor ionization energy and the resultant difficulty in achieving high free hole concentrations at room temperature. For n-type GaN, however, significant progress has been reported with reactive Ti-based metalization schemes or the use of graded InGaN layers. The present status of these approaches will be reviewed.

  20. Beyond amorphous organic semiconductors

    Science.gov (United States)

    Hanna, Jun-ichi

    2003-07-01

    Recently it has been discovered that some types of liquid crystals, which believed to be governed by ionic conduction, exhibit a very fast electronic conduction. Their charge carrier transport is characterized by high mobility over 10-2 cm2/Vs independent of electric field and temperature. Now, the liquid crystals are being recognized as a new class of organic semiconductors. In this article, a new aspect of liquid crystals as a self-organizing molecular semiconductor are reviewed, focused on their basic charge carrier transport properties and discussed in comparison with those of molecular crystals and amorphous materials. And it is concluded that the liquid crystal is promising as a quality organic semiconductor for the devices that require a high mobility.

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

    Science.gov (United States)

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

    2015-12-01

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

  2. Semiconductors for organic transistors

    OpenAIRE

    Antonio Facchetti

    2007-01-01

    Organic molecules/polymers with a π-conjugated (hetero)aromatic backbone are capable of transporting charge and interact efficiently with light. Therefore, these systems can act as semiconductors in opto-electronic devices similar to inorganic materials. However, organic chemistry offers tools for tailoring materials' functional properties via modifications of the molecular/monomeric units, opening new possibilities for inexpensive device manufacturing. This article reviews the fundamental as...

  3. Chromophore fluorination enhances crystallization and stability of soluble anthradithiophene semiconductors.

    Science.gov (United States)

    Subramanian, Sankar; Park, Sung Kyu; Parkin, Sean R; Podzorov, Vitaly; Jackson, Thomas N; Anthony, John E

    2008-03-05

    We report dramatic improvements in the stability and crystallinity arising from partial fluorination of soluble anthradithiophene derivatives. These fluorinated materials still behave as p-type semiconductors but with dramatic increases in thermal and photostability compared to the non-fluorinated derivatives. The triethylsilyl-substituted material forms highly crystalline films even from spin-cast solutions, leading to devices with maximum hole mobility greater than 1.0 cm(2)/V s. In contrast, the triisopropylsilyl derivative forms large, high-quality crystals that could serve as the substrate for transistor fabrication. For this compound, mobility as high as 0.1 cm(2)/V s was measured on the free-standing crystal.

  4. P-type conductivity in annealed strontium titanate

    Energy Technology Data Exchange (ETDEWEB)

    Poole, Violet M.; Corolewski, Caleb D.; McCluskey, Matthew D., E-mail: mattmcc@wsu.edu [Department of Physics and Astronomy, Washington State University, Pullman, WA 99164-2814 (United States)

    2015-12-15

    Hall-effect measurements indicate p-type conductivity in bulk, single-crystal strontium titanate (SrTiO{sub 3}, or STO) samples that were annealed at 1200°C. Room-temperature mobilities above 100 cm{sup 2}/V s were measured, an order of magnitude higher than those for electrons (5-10 cm{sup 2}/V s). Average hole densities were in the 10{sup 9}-10{sup 10} cm{sup −3} range, consistent with a deep acceptor.

  5. Synthesis and characterization by solid-state impedance spectroscopy of semiconductor Cu2ZnSnS4 material for photovoltaic technologies

    Science.gov (United States)

    Muñoz, M.; Vera-López, E.; Gómez-Cuaspud, J. A.; Pineda-Triana, Y.

    2017-01-01

    Current work is focused on the synthesis and characterization of a Cu2ZnSnS4 material (Abbreviated CZTS), identified as a potential candidate for the manufacture of photovoltaic cells. The material was obtained by means of a hydrothermal route which permits a simple and economical alternative to synthesize advanced materials for photovoltaic applications. The synthesis of a solid started from corresponding metal nitrates of Cu(NO3)2.6H2O, Zn(NO3)2, Sn(NO3)4.6H2O and thiourea as S source, which were dissolved in deionized water until complete a 1.0mol L-1 concentration. The solution was kept in a Teflon lined steel vessel with magnetic stirring (150 rpm) and treated at 300°C for 12 hours to form the crystalline phase. The initial characterization of solid was done using UV spectroscopy to validate the chemical process and identify the corresponding Band-gap around (1.43eV). The structural characterization by X-ray diffraction, confirmed the presence of nanometric solids (140-260nm). The morphological characterization by SEM analysis evidenced a homogeneous material in the form of micrometric aggregates, by a related synthesis method. Finally, the electrical characterization by means of solid state impedance spectroscopy demonstrated a semiconductor behaviour which evidenced the transport phenomena associated with a Warburg resistance.

  6. Microwave assisted synthesis and characterisation of a zinc oxide/tobacco mosaic virus hybrid material. An active hybrid semiconductor in a field-effect transistor device.

    Science.gov (United States)

    Sanctis, Shawn; Hoffmann, Rudolf C; Eiben, Sabine; Schneider, Jörg J

    2015-01-01

    Tobacco mosaic virus (TMV) has been employed as a robust functional template for the fabrication of a TMV/zinc oxide field effect transistor (FET). A microwave based approach, under mild conditions was employed to synthesize stable zinc oxide (ZnO) nanoparticles, employing a molecular precursor. Insightful studies of the decomposition of the precursor were done using NMR spectroscopy and material characterization of the hybrid material derived from the decomposition was achieved using dynamic light scattering (DLS), transmission electron microscopy (TEM), grazing incidence X-ray diffractometry (GI-XRD) and atomic force microscopy (AFM). TEM and DLS data confirm the formation of crystalline ZnO nanoparticles tethered on top of the virus template. GI-XRD investigations exhibit an orientated nature of the deposited ZnO film along the c-axis. FET devices fabricated using the zinc oxide mineralized virus template material demonstrates an operational transistor performance which was achieved without any high-temperature post-processing steps. Moreover, a further improvement in FET performance was observed by adjusting an optimal layer thickness of the deposited ZnO on top of the TMV. Such a bio-inorganic nanocomposite semiconductor material accessible using a mild and straightforward microwave processing technique could open up new future avenues within the field of bio-electronics.

  7. Microwave assisted synthesis and characterisation of a zinc oxide/tobacco mosaic virus hybrid material. An active hybrid semiconductor in a field-effect transistor device

    Directory of Open Access Journals (Sweden)

    Shawn Sanctis

    2015-03-01

    Full Text Available Tobacco mosaic virus (TMV has been employed as a robust functional template for the fabrication of a TMV/zinc oxide field effect transistor (FET. A microwave based approach, under mild conditions was employed to synthesize stable zinc oxide (ZnO nanoparticles, employing a molecular precursor. Insightful studies of the decomposition of the precursor were done using NMR spectroscopy and material characterization of the hybrid material derived from the decomposition was achieved using dynamic light scattering (DLS, transmission electron microscopy (TEM, grazing incidence X-ray diffractometry (GI-XRD and atomic force microscopy (AFM. TEM and DLS data confirm the formation of crystalline ZnO nanoparticles tethered on top of the virus template. GI-XRD investigations exhibit an orientated nature of the deposited ZnO film along the c-axis. FET devices fabricated using the zinc oxide mineralized virus template material demonstrates an operational transistor performance which was achieved without any high-temperature post-processing steps. Moreover, a further improvement in FET performance was observed by adjusting an optimal layer thickness of the deposited ZnO on top of the TMV. Such a bio-inorganic nanocomposite semiconductor material accessible using a mild and straightforward microwave processing technique could open up new future avenues within the field of bio-electronics.

  8. Elastic constants determined by nanoindentation for p-type thermoelectric half-Heusler

    Energy Technology Data Exchange (ETDEWEB)

    Gahlawat, S.; Wheeler, L.; White, K. W., E-mail: zren@uh.edu, E-mail: kwwhite@uh.edu [Department of Mechanical Engineering, University of Houston, Houston, Texas 77204 (United States); He, R.; Chen, S.; Ren, Z. F., E-mail: zren@uh.edu, E-mail: kwwhite@uh.edu [Department of Physics and TcSUH, University of Houston, Houston, Texas 77204 (United States)

    2014-08-28

    This paper presents a study of the elastic properties of the p-type thermoelectric half-Heusler material, Hf{sub 0.44}Zr{sub 0.44}Ti{sub 0.12}CoSb{sub 0.8}Sn{sub 0.2}, using nanoindentation. Large grain-sized polycrystalline specimens were fabricated for these measurements, providing sufficient indentation targets within single grains. Electron Backscatter Diffraction methods indexed the target grains for the correlation needed for our elastic analysis of individual single crystals for this cubic thermoelectric material. Elastic properties, including the Zener ratio and the Poisson ratio, obtained from the elasticity tensor are also reported.

  9. Sustained hole inversion layer in a wide-bandgap metal-oxide semiconductor with enhanced tunnel current.

    Science.gov (United States)

    Shoute, Gem; Afshar, Amir; Muneshwar, Triratna; Cadien, Kenneth; Barlage, Douglas

    2016-02-04

    Wide-bandgap, metal-oxide thin-film transistors have been limited to low-power, n-type electronic applications because of the unipolar nature of these devices. Variations from the n-type field-effect transistor architecture have not been widely investigated as a result of the lack of available p-type wide-bandgap inorganic semiconductors. Here, we present a wide-bandgap metal-oxide n-type semiconductor that is able to sustain a strong p-type inversion layer using a high-dielectric-constant barrier dielectric when sourced with a heterogeneous p-type material. A demonstration of the utility of the inversion layer was also investigated and utilized as the controlling element in a unique tunnelling junction transistor. The resulting electrical performance of this prototype device exhibited among the highest reported current, power and transconductance densities. Further utilization of the p-type inversion layer is critical to unlocking the previously unexplored capability of metal-oxide thin-film transistors, such applications with next-generation display switches, sensors, radio frequency circuits and power converters.

  10. Sustained hole inversion layer in a wide-bandgap metal-oxide semiconductor with enhanced tunnel current

    Science.gov (United States)

    Shoute, Gem; Afshar, Amir; Muneshwar, Triratna; Cadien, Kenneth; Barlage, Douglas

    2016-02-01

    Wide-bandgap, metal-oxide thin-film transistors have been limited to low-power, n-type electronic applications because of the unipolar nature of these devices. Variations from the n-type field-effect transistor architecture have not been widely investigated as a result of the lack of available p-type wide-bandgap inorganic semiconductors. Here, we present a wide-bandgap metal-oxide n-type semiconductor that is able to sustain a strong p-type inversion layer using a high-dielectric-constant barrier dielectric when sourced with a heterogeneous p-type material. A demonstration of the utility of the inversion layer was also investigated and utilized as the controlling element in a unique tunnelling junction transistor. The resulting electrical performance of this prototype device exhibited among the highest reported current, power and transconductance densities. Further utilization of the p-type inversion layer is critical to unlocking the previously unexplored capability of metal-oxide thin-film transistors, such applications with next-generation display switches, sensors, radio frequency circuits and power converters.

  11. Fabrication of p-type lithium niobate crystals by molybdenum doping and polarization

    Science.gov (United States)

    Tian, Tian; Kong, Yongfa; Liu, Hongde; Liu, Shiguo; Li, Wei; Chen, Shaolin; Xu, Jiayue

    2017-06-01

    The lack of p-type lithium niobate limits it serving as an active material. A series of Mo-doped and pure congruent lithium niobate crystals were grown by Czochralski method under different polarization conditions. Their dominant carrier species were characterized by holographic experiment. The results showed dominant charge carrier species may be changed from electrons to holes when lithium niobate crystal was doped with Mo ions and polarized under the current of 70mA for 30 minutes. It indicated that p-type lithium niobate crystal could be fabricated by Mo-doping and suitably controlling the polarization condition. Mo-doped lithium niobate crystals can be a promising candidate for active components.

  12. Perspectives of High-Temperature Thermoelectric Applications and p-type and n-type Aluminoborides

    Science.gov (United States)

    Mori, T.

    2016-10-01

    A need exists to develop high-temperature thermoelectric materials which can utilize high-temperature unutilized/waste heat in thermal power plants, steelworks, factories, incinerators, etc., and also focused solar power. The thermal power plant topping application is of potential high impact since it can sizably increase the efficiency of power plants which are the major supply of electrical power for many countries. Higher borides are possible candidates for their particular high-temperature stability, generally large Seebeck coefficients, α, and intrinsic low thermal conductivity. Excellent (|α| > 200 μV/K) p-type or n-type behavior was recently achieved in the aluminoboride YAl x B14 by varying the occupancy of Al sites, x. Finding p-type and n-type counterparts has long been a difficulty of thermoelectric research not limited to borides. This paper reviews possible high-temperature thermoelectric applications, and recent developments and perspectives of thermoelectric aluminoborides.

  13. Nanocrystalline ZnON; High mobility and low band gap semiconductor material for high performance switch transistor and image sensor application

    Science.gov (United States)

    Lee, Eunha; Benayad, Anass; Shin, Taeho; Lee, HyungIk; Ko, Dong-Su; Kim, Tae Sang; Son, Kyoung Seok; Ryu, Myungkwan; Jeon, Sanghun; Park, Gyeong-Su

    2014-01-01

    Interest in oxide semiconductors stems from benefits, primarily their ease of process, relatively high mobility (0.3–10 cm2/vs), and wide-bandgap. However, for practical future electronic devices, the channel mobility should be further increased over 50 cm2/vs and wide-bandgap is not suitable for photo/image sensor applications. The incorporation of nitrogen into ZnO semiconductor can be tailored to increase channel mobility, enhance the optical absorption for whole visible light and form uniform micro-structure, satisfying the desirable attributes essential for high performance transistor and visible light photo-sensors on large area platform. Here, we present electronic, optical and microstructural properties of ZnON, a composite of Zn3N2 and ZnO. Well-optimized ZnON material presents high mobility exceeding 100 cm2V−1s−1, the band-gap of 1.3 eV and nanocrystalline structure with multiphase. We found that mobility, microstructure, electronic structure, band-gap and trap properties of ZnON are varied with nitrogen concentration in ZnO. Accordingly, the performance of ZnON-based device can be adjustable to meet the requisite of both switch device and image-sensor potentials. These results demonstrate how device and material attributes of ZnON can be optimized for new device strategies in display technology and we expect the ZnON will be applicable to a wide range of imaging/display devices. PMID:24824778

  14. Microbial toxicity of ionic species leached from the II-VI semiconductor materials, cadmium telluride (CdTe) and cadmium selenide (CdSe).

    Science.gov (United States)

    Ramos-Ruiz, Adriana; Zeng, Chao; Sierra-Alvarez, Reyes; Teixeira, Luiz H; Field, Jim A

    2016-11-01

    This work investigated the microbial toxicity of soluble species that can potentially be leached from the II-VI semiconductor materials, cadmium telluride and cadmium selenide. The soluble ions tested included: cadmium, selenite, selenate, tellurite, and tellurate. Their toxicity towards the acetoclastic and hydrogen-consuming trophic groups in a methanogenic consortium as well as towards a bioluminescent marine bacterium, Aliivibrio fischeri (Microtox(®) test), was assessed. The acetoclastic methanogenic activity was the most affected as evidenced by the low 50% inhibiting concentrations (IC50) values obtained of 8.6 mg L(-1) for both cadmium and tellurite, 10.2 mg L(-1) for tellurate, and 24.1 mg L(-1) for selenite. Both tellurium oxyanions caused a strong inhibition of acetoclastic methanogenesis at low concentrations, each additional increment in concentration provided progressively less inhibition increase. In the case of the hydrogenotrophic methanogenesis, cadmium followed by selenite caused the greatest inhibition with IC50 values of 2.9 and 18.0 mg L(-1), respectively. Tellurite caused a moderate effect as evidenced by a 36.8% inhibition of the methanogenic activity at the highest concentration tested, and a very mild effect of tellurate was observed. Microtox(®) analyses showed a noteworthy inhibition of cadmium, selenite, and tellurite with 50% loss in bioluminescence after 30 min of exposure of 5.5, 171.1, and 458.6 mg L(-1), respectively. These results suggest that the leaching of cadmium, tellurium and selenium ions from semiconductor materials can potentially cause microbial toxicity.

  15. Semiconductor Lasers and Their Application in Optical Fiber Communication.

    Science.gov (United States)

    Agrawal, Govind P.

    1985-01-01

    Working principles and operating characteristics of the extremely compact and highly efficient semiconductor lasers are explained. Topics include: the p-n junction; Fabry-Perot cavity; heterostructure semiconductor lasers; materials; emission characteristics; and single-frequency semiconductor lasers. Applications for semiconductor lasers include…

  16. Performance analysis of series-shunt and TEE types of microwave switches of different semiconductor materials for Satellite communications

    Directory of Open Access Journals (Sweden)

    Cirilo Gabino León Vega

    2014-01-01

    Full Text Available Se presenta un análisis de desempeño de conmutadores de microondas compuestos, de una entrada y una salida (SPST, diseñados con diodos p-i-n tipo masa con diferentes tipos de materiales semiconductores para las bandas de frecuencia Ku y Ka. Las dos configuraciones de conmutadores compuestos más comunes son aquellos con diodos p-i-n ubicados en diseños serie-paralelo y serie-paralelo-serie (TEE y aquí son analizados utilizando materiales semiconductores de Si, GaAs, GaN-WZ, GaN-ZB, GaSb, InP y SiC. Se presenta la metodología utilizada en los cálculos de resistencia serie y capacitancia de unión en los diodos p-i-n con el propósito de calcular los parámetros de desempeño propios de cada dispositivo conmutador. Estos parámetros son pérdida de inserción y aislamiento. Los conmutadores de tipo serie-paralelo, exceptuando el conmutador basado en diodo p-i-n de SiC-6 H, exhiben pérdidas de inserción menores a 0.2 dB y aislamiento hasta 41dB a la frecuencia de operación de 12 GHz. El conmutador diodo p-i-n tipo TEE con base en GaN-ZB tiene la mejor respuesta de pérdida de inserción menor a 0.23 dB y aislamiento hasta 52 dB, a las frecuencias de operación de 12 GHz y 30 GHz. El conmutador compuesto con base en diodo p-i-n de GaSb alcanza el mejor desempeño a la frecuencia de 12 GHz. Los conmutadores de microondas con configuración TEE tienen respuestas satisfactorias para la frecuencia de 30 GHz.

  17. Characterization of the Structural and Optical Properties of III-V Semiconductor Materials for Solar Cell Applications

    Science.gov (United States)

    Xie, Hongen

    The work contained in this dissertation is focused on the structural and optical properties of III-V semiconductor structures for solar cell applications. By using transmission electron microscopy, many of their structural properties have been investigated, including morphology, defects, and strain relaxation. The optical properties of the semiconductor structures have been studied by photoluminescence and cathodoluminescence. Part of this work is focused on InAs quantum dots (QDs) embedded in AlGaAs matrices. This QD system is important for the realization of intermediate-band solar cells, which has three light absorption paths for high efficiency photovoltaics. The suppression of plastic strain relaxation in the QDs shows a significant improvement of the optoelectronic properties. A partial capping followed by a thermal annealing step is used to achieve spool-shaped QDs with a uniform height following the thickness of the capping layer. This step keeps the height of the QDs below a critical value that is required for plastic relaxation. The spool-shaped QDs exhibit two photoluminescence peaks that are attributed to ground and excited state transitions. The luminescence peak width is associated with the QD diameter distribution. An InAs cover layer formed during annealing is found responsible for the loss of the confinement of the excited states in smaller QDs. The second part of this work is focused on the investigation of the In xGa1-xN thin films having different bandgaps for double-junction solar cells. InxGa1-xN films with x ≤ 0.15 were grown by metal organic chemical vapor deposition. The defects in films with different indium contents have been studied. Their effect on the optical properties of the film have been investigated by cathodoluminescence. InxGa 1-xN films with indium contents higher than 20% were grown by molecular beam epitaxy. The strain relaxation in the films has been measured from electron diffraction patterns taken in cross-sectional TEM

  18. Metal Fluoride Inhibition of a P-type H+ Pump

    Science.gov (United States)

    Pedersen, Jesper Torbøl; Falhof, Janus; Ekberg, Kira; Buch-Pedersen, Morten Jeppe; Palmgren, Michael

    2015-01-01

    The plasma membrane H+-ATPase is a P-type ATPase responsible for establishing electrochemical gradients across the plasma membrane in fungi and plants. This essential proton pump exists in two activity states: an autoinhibited basal state with a low turnover rate and a low H+/ATP coupling ratio and an activated state in which ATP hydrolysis is tightly coupled to proton transport. Here we characterize metal fluorides as inhibitors of the fungal enzyme in both states. In contrast to findings for other P-type ATPases, inhibition of the plasma membrane H+-ATPase by metal fluorides was partly reversible, and the stability of the inhibition varied with the activation state. Thus, the stability of the ATPase inhibitor complex decreased significantly when the pump transitioned from the activated to the basal state, particularly when using beryllium fluoride, which mimics the bound phosphate in the E2P conformational state. Taken together, our results indicate that the phosphate bond of the phosphoenzyme intermediate of H+-ATPases is labile in the basal state, which may provide an explanation for the low H+/ATP coupling ratio of these pumps in the basal state. PMID:26134563

  19. Organic semiconductors in a spin

    CERN Document Server

    Samuel, I

    2002-01-01

    A little palladium can go a long way in polymer-based light-emitting diodes. Inorganic semiconductors such as silicon and gallium arsenide are essential for countless applications in everyday life, ranging from PCs to CD players. However, while they offer unrivalled computational speed, inorganic semiconductors are also rigid and brittle, which means that they are less suited to applications such as displays and flexible electronics. A completely different class of materials - organic semiconductors - are being developed for these applications. Organic semiconductors have many attractive features: they are easy to make, they can emit visible light, and there is tremendous scope for tailoring their properties to specific applications by changing their chemical structure. Research groups and companies around the world have developed a wide range of organic-semiconductor devices, including transistors, light-emitting diodes (LEDs), solar cells and lasers. (U.K.)

  20. CuSbS2: a promising semiconductor photo-absorber material for quantum dot sensitized solar cells.

    Science.gov (United States)

    Liu, Zhifeng; Huang, Jiajun; Han, Jianhuan; Hong, Tiantian; Zhang, Jing; Liu, Zhihua

    2016-06-22

    A facile, low-cost, simple solution-based process for preparing novel promising chalcostibite CuSbS2 sensitized ZnO nanorod arrays, and the application of these as photoanodes of semiconductor quantum dot sensitized inorganic-organic solar cells (QDSSCs) is reported for the first time. ZnO/CuSbS2 nanofilms were designed and prepared through a simple successive ionic layer adsorption and reaction (SILAR) method and heat treatment process by employing ZnO nanorods as reactive templates. Novel efficient QDSSCs based on the ZnO/CuSbS2 nanofilms plus a solid electrolyte of poly(3-hexylthiophene) (P3HT) were formed, and a power conversion efficiency of 1.61% was achieved. The excellent photoelectric performance is attributed to the improved light absorption efficiency, widened light absorption region, ideal band gap value, and high speed electron injection and transportation. The results demonstrate that a novel ternary sensitizer (I-V-VI2) can be synthesized via a low-cost method as described here and has great promising potential as a sensitizer in solar cells.

  1. Novel material for nonvolatile ovonic unified memory(OUM)-Ag11In12Te26Sb51 phase change semiconductor

    Institute of Scientific and Technical Information of China (English)

    Liu Bo; Song Zhi-Tang; Zhang Ting; Feng Song-Lin; Gan Fu-Xi

    2004-01-01

    In this paper, Ag11In12Te26Sb51 phase change semiconductor films have been prepared by dc sputtering. The crystallization behaviour of amorphous Ag11In12Te26Sb51 thin films was investigated by using differential scanning calorimetry and x-ray diffraction. It was found that the crystallization temperature is about 483K and the melting temperature is 754.8K and the activation energy for crystallization, Ea, is 2.07eV. The crystalline Ag11In12Te26Sb51 films were obtained using initializer. The initialization conditions have a great effect on the sheet resistance of Ag11In12Te26Sb51films. We found that the effect of the initialization condition on the sheet resistance can be ascribed to the crystallinity of Ag11In12Te26Sb51 films. The sheet resistance of the amorphous (Ramo) film is found to be larger than 1× 106Ω and that of the crystalline (Rcry) film lies in the range from about 103 to 104Ω. So we have the ratio Ramo/Rcry=10 2 ~ 103,which is sufficiently large for application in memory devices.

  2. Determination of bulk diffusion lengths for angle-lapped semiconductor material via the scanning electron microscope: A theoretical analysis

    Science.gov (United States)

    Vonroos, O.

    1978-01-01

    A standard procedure for the determination of the minority carrier diffusion length by means of a scanning electron microscope (SEM) consists in scanning across an angle-lapped surface of a P-N junction and measuring the resultant short circuit current I sub sc as a function of beam position. A detailed analysis of the I sub sc originating from this configuration is presented. It is found that, for a point source excitation, the I sub sc depends very simply on x, the variable distance between the surface and the junction edge. The expression for the I sub sc of a planar junction device is well known. If d, the constant distance between the plane of the surface of the semiconductor and the junction edge in the expression for the I of a planar junction is merely replaced by x, the variable distance of the corresponding angle-lapped junction, an expression results which is correct to within a small fraction of a percent as long as the angle between the surfaces, 2 theta sub 1, is smaller than 10 deg.

  3. Ultrathin Epitaxial Ferromagneticγ-Fe2O3Layer as High Efficiency Spin Filtering Materials for Spintronics Device Based on Semiconductors

    KAUST Repository

    Li, Peng

    2016-06-01

    In spintronics, identifying an effective technique for generating spin-polarized current has fundamental importance. The spin-filtering effect across a ferromagnetic insulating layer originates from unequal tunneling barrier heights for spin-up and spin-down electrons, which has shown great promise for use in different ferromagnetic materials. However, the low spin-filtering efficiency in some materials can be ascribed partially to the difficulty in fabricating high-quality thin film with high Curie temperature and/or partially to the improper model used to extract the spin-filtering efficiency. In this work, a new technique is successfully developed to fabricate high quality, ferrimagnetic insulating γ-Fe2O3 films as spin filter. To extract the spin-filtering effect of γ-Fe2O3 films more accurately, a new model is proposed based on Fowler–Nordheim tunneling and Zeeman effect to obtain the spin polarization of the tunneling currents. Spin polarization of the tunneled current can be as high as −94.3% at 2 K in γ-Fe2O3 layer with 6.5 nm thick, and the spin polarization decays monotonically with temperature. Although the spin-filter effect is not very high at room temperature, this work demonstrates that spinel ferrites are very promising materials for spin injection into semiconductors at low temperature, which is important for development of novel spintronics devices. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

  4. p-Type NiO Hybrid Visible Photodetector.

    Science.gov (United States)

    Mallows, John; Planells, Miquel; Thakare, Vishal; Bhosale, Reshma; Ogale, Satishchandra; Robertson, Neil

    2015-12-23

    A novel hybrid visible-light photodetector was created using a planar p-type inorganic NiO layer in a junction with an organic electron acceptor layer. The effect of different oxygen pressures on formation of the NiO layer by pulsed laser deposition shows that higher pressure increases the charge carrier density of the film and lowers the dark current in the device. The addition of a monolayer of small molecules containing conjugated π systems and carboxyl groups at the device interface was also investigated and with correct alignment of the energy levels improves the device performance with respect to the quantum efficiency, responsivity, and photogeneration. The thickness of the organic layer was also optimized for the device, giving a responsivity of 1.54 × 10(-2) A W(-1) in 460 nm light.

  5. Elucidating Functional Aspects of P-type ATPases

    DEFF Research Database (Denmark)

    Autzen, Henriette Elisabeth

    2015-01-01

    similar to that of the wild type (WT) protein. The discrepancy between the newly determined crystal structure of LpCopA and the functional manifestations of the missense mutation in human CopA, could indicate that LpCopA is insufficient in structurally elucidating the effect of disease-causing mutations...... cancer and pathogenic microbes. The goal of this Ph.D. dissertation was to functionally characterize SERCA1a and CopA from Legionella pneumophila (LpCopA) through a range of different methods within structural biology. Crystallographic studies of SERCA1a led to a newly determined crystal structure......P-type ATPases are proteins that act to maintain ion homeostasis and electrochemical gradients through the translocation of cations across cell membranes. Underscoring their significance in humans, dysfunction of the ATPases can lead to crucial diseases. Dysfunction of the sarco...

  6. Study on the p-type QWIP-LED device

    Institute of Scientific and Technical Information of China (English)

    ZHEN; Honglou; XIONG; Dayuan; ZHOU; Xuchang; LI; Ning; SHAO; Jun; LU; Wei

    2006-01-01

    A p-type quantum well infrared photodetector (QWIP) integrated with a light-emitting diode (LED) (named QWIP-LED) was fabricated and studied. The infrared photo-response spectrum was obtained from the device resistance variation and the near-infrared photo-emission intensity variation. A good agreement between these two spectra was observed, which demonstrates that the long-wavelength infrared radiation around 7.5 μm has been transferred to the near-infrared light at 0.8 μm by the photo-electronic process in the QWIP-LED structure. Moreover, the experimentally observed infrared response wavelength is in good agreement with the theoretical calculation value of 7.7 μm. The results on the upconversion of the infrared radiation will be very useful for the new infrared focal plane array technology.

  7. Comparing n- and p-type polycrystalline silicon absorbers in thin-film solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Deckers, J. [imec, Kapeldreef 75, B-3001 Heverlee, Leuven (Belgium); ESAT, KU Leuven, Kardinaal Mercierlaan 94, B-3001 Heverlee, Leuven (Belgium); Bourgeois, E. [Institute for Materials Research (IMO), Hasselt University, Wetenschapspark 1, B-3590 Diepenbeek (Belgium); IMOMEC, IMEC vzw, Wetenschapspark 1, B-3590 Diepenbeek (Belgium); Jivanescu, M. [Department of Physics and Astronomy, University of Leuven, Celestijnenlaan 200D, B-3001 Heverlee, Leuven (Belgium); Abass, A. [Photonics Research Group (INTEC), Ghent University-imec, Sint-Pietersnieuwstraat 41, B-9000 Ghent (Belgium); Van Gestel, D.; Van Nieuwenhuysen, K.; Douhard, B. [imec, Kapeldreef 75, B-3001 Heverlee, Leuven (Belgium); D' Haen, J.; Nesladek, M.; Manca, J. [Institute for Materials Research (IMO), Hasselt University, Wetenschapspark 1, B-3590 Diepenbeek (Belgium); IMOMEC, IMEC vzw, Wetenschapspark 1, B-3590 Diepenbeek (Belgium); Gordon, I.; Bender, H. [imec, Kapeldreef 75, B-3001 Heverlee, Leuven (Belgium); Stesmans, A. [Department of Physics and Astronomy, University of Leuven, Celestijnenlaan 200D, B-3001 Heverlee, Leuven (Belgium); Mertens, R.; Poortmans, J. [imec, Kapeldreef 75, B-3001 Heverlee, Leuven (Belgium); ESAT, KU Leuven, Kardinaal Mercierlaan 94, B-3001 Heverlee, Leuven (Belgium)

    2015-03-31

    We have investigated fine grained polycrystalline silicon thin films grown by direct chemical vapor deposition on oxidized silicon substrates. More specifically, we analyze the influence of the doping type on the properties of this model polycrystalline silicon material. This includes an investigation of defect passivation and benchmarking of minority carrier properties. In our investigation, we use a variety of characterization techniques to probe the properties of the investigated polycrystalline silicon thin films, including Fourier Transform Photoelectron Spectroscopy, Electron Spin Resonance, Conductivity Activation, and Suns-Voc measurements. Amphoteric silicon dangling bond defects are identified as the most prominent defect type present in these layers. They are the primary recombination center in the relatively lowly doped polysilicon thin films at the heart of the current investigation. In contrast with the case of solar cells based on Czochralski silicon or multicrystalline silicon wafers, we conclude that no benefit is found to be associated with the use of n-type dopants over p-type dopants in the active absorber of the investigated polycrystalline silicon thin-film solar cells. - Highlights: • Comparison of n- and p-type absorbers for thin-film poly-Si solar cells • Extensive characterization of the investigated layers' characteristics • Literature review pertaining the use of n-type and p-type dopants in silicon.

  8. Demethoxycurcumin Is A Potent Inhibitor of P-Type ATPases from Diverse Kingdoms of Life.

    Science.gov (United States)

    Dao, Trong Tuan; Sehgal, Pankaj; Tung, Truong Thanh; Møller, Jesper Vuust; Nielsen, John; Palmgren, Michael; Christensen, Søren Brøgger; Fuglsang, Anja Thoe

    2016-01-01

    P-type ATPases catalyze the active transport of cations and phospholipids across biological membranes. Members of this large family are involved in a range of fundamental cellular processes. To date, a substantial number of P-type ATPase inhibitors have been characterized, some of which are used as drugs. In this work a library of natural compounds was screened and we first identified curcuminoids as plasma membrane H+-ATPases inhibitors in plant and fungal cells. We also found that some of the commercial curcumins contain several curcuminoids. Three of these were purified and, among the curcuminoids, demethoxycurcumin was the most potent inhibitor of all tested P-type ATPases from fungal (Pma1p; H+-ATPase), plant (AHA2; H+-ATPase) and animal (SERCA; Ca2+-ATPase) cells. All three curcuminoids acted as non-competitive antagonist to ATP and hence may bind to a highly conserved allosteric site of these pumps. Future research on biological effects of commercial preparations of curcumin should consider the heterogeneity of the material.

  9. Semiconductor Nanocrystals for Biological Imaging

    Energy Technology Data Exchange (ETDEWEB)

    Fu, Aihua; Gu, Weiwei; Larabell, Carolyn; Alivisatos, A. Paul

    2005-06-28

    Conventional organic fluorophores suffer from poor photo stability, narrow absorption spectra and broad emission feature. Semiconductor nanocrystals, on the other hand, are highly photo-stable with broad absorption spectra and narrow size-tunable emission spectra. Recent advances in the synthesis of these materials have resulted in bright, sensitive, extremely photo-stable and biocompatible semiconductor fluorophores. Commercial availability facilitates their application in a variety of unprecedented biological experiments, including multiplexed cellular imaging, long-term in vitro and in vivo labeling, deep tissue structure mapping and single particle investigation of dynamic cellular processes. Semiconductor nanocrystals are one of the first examples of nanotechnology enabling a new class of biomedical applications.

  10. Boron doping a semiconductor particle

    Science.gov (United States)

    Stevens, Gary Don; Reynolds, Jeffrey Scott; Brown, Louanne Kay

    1998-06-09

    A method (10,30) of boron doping a semiconductor particle using boric acid to obtain a p-type doped particle. Either silicon spheres or silicon powder is mixed with a diluted solution of boric acid having a predetermined concentration. The spheres are dried (16), with the boron film then being driven (18) into the sphere. A melt procedure mixes the driven boron uniformly throughout the sphere. In the case of silicon powder, the powder is metered out (38) into piles and melted/fused (40) with an optical furnace. Both processes obtain a p-type doped silicon sphere with desired resistivity. Boric acid is not a restricted chemical, is inexpensive, and does not pose any special shipping, handling, or disposal requirements.

  11. Three dimensional strained semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    Voss, Lars; Conway, Adam; Nikolic, Rebecca J.; Leao, Cedric Rocha; Shao, Qinghui

    2016-11-08

    In one embodiment, an apparatus includes a three dimensional structure comprising a semiconductor material, and at least one thin film in contact with at least one exterior surface of the three dimensional structure for inducing a strain in the structure, the thin film being characterized as providing at least one of: an induced strain of at least 0.05%, and an induced strain in at least 5% of a volume of the three dimensional structure. In another embodiment, a method includes forming a three dimensional structure comprising a semiconductor material, and depositing at least one thin film on at least one surface of the three dimensional structure for inducing a strain in the structure, the thin film being characterized as providing at least one of: an induced strain of at least 0.05%, and an induced strain in at least 5% of a volume of the structure.

  12. Computational prediction of lattice defects in multinary comp ound semiconductors as photovoltaic materials%多元半导体光伏材料中晶格缺陷的计算预测

    Institute of Scientific and Technical Information of China (English)

    袁振坤; 许鹏; 陈时友

    2015-01-01

    defects in two types of multinary photovoltaic semiconductors, Cu2ZnSn(S,Se)4 and H3NH3PbI3. The result of the increased number of component elements involves various competing secondary phases, limiting the formation of single-phase multinary compound semiconductors. Unlike ternary CuInSe2, the dominant defect that determines the p-type conductivity in Cu2ZnSnS4 is Cu-on-Zn antisite (CuZn) defect rather than the copper vacancy (VCu). However, the ionization level of CuZn is deeper than that of VCu. The self-compensated defect pairs such as [2CuZn+SnZn] are easy to form in Cu2ZnSnS4, which causes band gap fluctuations and limits the Voc of Cu2ZnSnS4 cells. Additionally the formation energies of deep level defects, SnZn and VS, are not sufficiently high in Cu2ZnSnS4, leading to poor lifetime of minority carriers and hence low Voc. In order to enhance the formation of VCu and suppress the formation of CuZn as well as deep level defects, a Cu-poor/Zn-rich growth condition is required. Compared with Cu2ZnSnS4, the concentration of deep level defects is predicted to be low in Cu2ZnSnSe4, therefore, the devices fabri-cated based on the Se-rich Cu2ZnSn(S,Se)4 alloys exhibit better performances. Unlike Cu2ZnSnS4 cells, the CH3NH3PbI3 cells exhibit rather high Voc and long minority-carrier life time. The un-usually benign defect physics of CH3NH3PbI3 is responsible for the remarkable performance of CH3NH3PbI3 cells. First, CH3NH3PbI3 shows that flexible conductivity is dependent on growth condition. This behavior is distinguished from common p-type photovoltaic semiconductor, in which the n-type doping is generally difficult. Second, in CH3NH3PbI3, defects with low formation energies create only shallow levels. Through controlling the carrier concentration (Fermi level) and growth condition, the formation of deep-level defect can be suppressed in CH3NH3PbI3. We conclude that the predicted results from the first-principles calculations are very useful for guiding the experimental

  13. High-throughput screening of thin-film semiconductor material libraries II: characterization of Fe-W-O libraries.

    Science.gov (United States)

    Meyer, Robert; Sliozberg, Kirill; Khare, Chinmay; Schuhmann, Wolfgang; Ludwig, Alfred

    2015-04-13

    Metal oxides are promising materials for solar water splitting. To identify suitable materials within the ternary system FeWO, thin-film material libraries with combined thickness and compositional gradients were synthesized by combinatorial reactive magnetron sputtering. These libraries (>1000 different samples) were investigated by means of structural and functional high-throughput characterization techniques to establish correlations between composition, crystallinity, morphology, thickness, and photocurrent density in the compositional range between (Fe6 W94 )Ox and (Fe61 W39 )Ox . In addition to the well-known phase WO3 , the binary phase W5 O14 and the ternary phase Fe2 O6 W show enhanced photoelectrochemical activity. The highest photocurrent density of 65 μA cm(-2) was achieved for the composition (Fe15 W85 )Ox , which contains the W5 O14 phase and has a thickness of 1060 nm.

  14. P-Type Silicon Strip Sensors for the new CMS Tracker at HL-LHC

    Science.gov (United States)

    Adam, W.; Bergauer, T.; Brondolin, E.; Dragicevic, M.; Friedl, M.; Frühwirth, R.; Hoch, M.; Hrubec, J.; König, A.; Steininger, H.; Waltenberger, W.; Alderweireldt, S.; Beaumont, W.; Janssen, X.; Lauwers, J.; Van Mechelen, P.; Van Remortel, N.; Van Spilbeeck, A.; Beghin, D.; Brun, H.; Clerbaux, B.; Delannoy, H.; De Lentdecker, G.; Fasanella, G.; Favart, L.; Goldouzian, R.; Grebenyuk, A.; Karapostoli, G.; Lenzi, Th.; Léonard, A.; Luetic, J.; Postiau, N.; Seva, T.; Vanlaer, P.; Vannerom, D.; Wang, Q.; Zhang, F.; Abu Zeid, S.; Blekman, F.; De Bruyn, I.; De Clercq, J.; D'Hondt, J.; Deroover, K.; Lowette, S.; Moortgat, S.; Moreels, L.; Python, Q.; Skovpen, K.; Van Mulders, P.; Van Parijs, I.; Bakhshiansohi, H.; Bondu, O.; Brochet, S.; Bruno, G.; Caudron, A.; Delaere, C.; Delcourt, M.; De Visscher, S.; Francois, B.; Giammanco, A.; Jafari, A.; Komm, M.; Krintiras, G.; Lemaitre, V.; Magitteri, A.; Mertens, A.; Michotte, D.; Musich, M.; Piotrzkowski, K.; Quertenmont, L.; Szilasi, N.; Vidal Marono, M.; Wertz, S.; Beliy, N.; Caebergs, T.; Daubie, E.; Hammad, G. H.; Härkönen, J.; Lampén, T.; Luukka, P.; Peltola, T.; Tuominen, E.; Tuovinen, E.; Eerola, P.; Tuuva, T.; Baulieu, G.; Boudoul, G.; Caponetto, L.; Combaret, C.; Contardo, D.; Dupasquier, T.; Gallbit, G.; Lumb, N.; Mirabito, L.; Perries, S.; Vander Donckt, M.; Viret, S.; Agram, J.-L.; Andrea, J.; Bloch, D.; Bonnin, C.; Brom, J.-M.; Chabert, E.; Chanon, N.; Charles, L.; Conte, E.; Fontaine, J.-Ch.; Gross, L.; Hosselet, J.; Jansova, M.; Tromson, D.; Autermann, C.; Feld, L.; Karpinski, W.; Kiesel, K. M.; Klein, K.; Lipinski, M.; Ostapchuk, A.; Pierschel, G.; Preuten, M.; Rauch, M.; Schael, S.; Schomakers, C.; Schulz, J.; Schwering, G.; Wlochal, M.; Zhukov, V.; Pistone, C.; Fluegge, G.; Kuensken, A.; Pooth, O.; Stahl, A.; Aldaya, M.; Asawatangtrakuldee, C.; Beernaert, K.; Bertsche, D.; Contreras-Campana, C.; Eckerlin, G.; Eckstein, D.; Eichhorn, T.; Gallo, E.; Garay Garcia, J.; Hansen, K.; Haranko, M.; Harb, A.; Hauk, J.; Keaveney, J.; Kalogeropoulos, A.; Kleinwort, C.; Lohmann, W.; Mankel, R.; Maser, H.; Mittag, G.; Muhl, C.; Mussgiller, A.; Pitzl, D.; Reichelt, O.; Savitskyi, M.; Schuetze, P.; Walsh, R.; Zuber, A.; Biskop, H.; Buhmann, P.; Centis-Vignali, M.; Garutti, E.; Haller, J.; Hoffmann, M.; Lapsien, T.; Matysek, M.; Perieanu, A.; Scharf, Ch.; Schleper, P.; Schmidt, A.; Schwandt, J.; Sonneveld, J.; Steinbrück, G.; Vormwald, B.; Wellhausen, J.; Abbas, M.; Amstutz, C.; Barvich, T.; Barth, Ch.; Boegelspacher, F.; De Boer, W.; Butz, E.; Caselle, M.; Colombo, F.; Dierlamm, A.; Freund, B.; Hartmann, F.; Heindl, S.; Husemann, U.; Kornmayer, A.; Kudella, S.; Muller, Th.; Simonis, H. J.; Steck, P.; Weber, M.; Weiler, Th.; Anagnostou, G.; Asenov, P.; Assiouras, P.; Daskalakis, G.; Kyriakis, A.; Loukas, D.; Paspalaki, L.; Siklér, F.; Veszprémi, V.; Bhardwaj, A.; Dalal, R.; Jain, G.; Ranjan, K.; Bakhshiansohl, H.; Behnamian, H.; Khakzad, M.; Naseri, M.; Cariola, P.; Creanza, D.; De Palma, M.; De Robertis, G.; Fiore, L.; Franco, M.; Loddo, F.; Silvestris, L.; Maggi, G.; Martiradonna, S.; My, S.; Selvaggi, G.; Albergo, S.; Cappello, G.; Chiorboli, M.; Costa, S.; Di Mattia, A.; Giordano, F.; Potenza, R.; Saizu, M. A.; Tricomi, A.; Tuve, C.; Barbagli, G.; Brianzi, M.; Ciaranfi, R.; Ciulli, V.; Civinini, C.; D'Alessandro, R.; Focardi, E.; Latino, G.; Lenzi, P.; Meschini, M.; Paoletti, S.; Russo, L.; Scarlini, E.; Sguazzoni, G.; Strom, D.; Viliani, L.; Ferro, F.; Lo Vetere, M.; Robutti, E.; Dinardo, M. E.; Fiorendi, S.; Gennai, S.; Malvezzi, S.; Manzoni, R. A.; Menasce, D.; Moroni, L.; Pedrini, D.; Azzi, P.; Bacchetta, N.; Bisello, D.; Dall'Osso, M.; Pozzobon, N.; Tosi, M.; De Canio, F.; Gaioni, L.; Manghisoni, M.; Nodari, B.; Riceputi, E.; Re, V.; Traversi, G.; Comotti, D.; Ratti, L.; Alunni Solestizi, L.; Biasini, M.; Bilei, G. M.; Cecchi, C.; Checcucci, B.; Ciangottini, D.; Fanò, L.; Gentsos, C.; Ionica, M.; Leonardi, R.; Manoni, E.; Mantovani, G.; Marconi, S.; Mariani, V.; Menichelli, M.; Modak, A.; Morozzi, A.; Moscatelli, F.; Passeri, D.; Placidi, P.; Postolache, V.; Rossi, A.; Saha, A.; Santocchia, A.; Storchi, L.; Spiga, D.; Androsov, K.; Azzurri, P.; Arezzini, S.; Bagliesi, G.; Basti, A.; Boccali, T.; Borrello, L.; Bosi, F.; Castaldi, R.; Ciampa, A.; Ciocci, M. A.; Dell'Orso, R.; Donato, S.; Fedi, G.; Giassi, A.; Grippo, M. T.; Ligabue, F.; Lomtadze, T.; Magazzu, G.; Martini, L.; Mazzoni, E.; Messineo, A.; Moggi, A.; Morsani, F.; Palla, F.; Palmonari, F.; Raffaelli, F.; Rizzi, A.; Savoy-Navarro, A.; Spagnolo, P.; Tenchini, R.; Tonelli, G.; Venturi, A.; Verdini, P. G.; Bellan, R.; Costa, M.; Covarelli, R.; Da Rocha Rolo, M.; Demaria, N.; Rivetti, A.; Dellacasa, G.; Mazza, G.; Migliore, E.; Monteil, E.; Pacher, L.; Ravera, F.; Solano, A.; Fernandez, M.; Gomez, G.; Jaramillo Echeverria, R.; Moya, D.; Gonzalez Sanchez, F. J.; Vila, I.; Virto, A. L.; Abbaneo, D.; Ahmed, I.; Albert, E.; Auzinger, G.; Berruti, G.; Bianchi, G.; Blanchot, G.; Bonnaud, J.; Caratelli, A.; Ceresa, D.; Christiansen, J.; Cichy, K.; Daguin, J.; D'Auria, A.; Detraz, S.; Deyrail, D.; Dondelewski, O.; Faccio, F.; Frank, N.; Gadek, T.; Gill, K.; Honma, A.; Hugo, G.; Jara Casas, L. M.; Kaplon, J.; Kornmayer, A.; Kottelat, L.; Kovacs, M.; Krammer, M.; Lenoir, P.; Mannelli, M.; Marchioro, A.; Marconi, S.; Mersi, S.; Martina, S.; Michelis, S.; Moll, M.; Onnela, A.; Orfanelli, S.; Pavis, S.; Peisert, A.; Pernot, J.-F.; Petagna, P.; Petrucciani, G.; Postema, H.; Rose, P.; Tropea, P.; Troska, J.; Tsirou, A.; Vasey, F.; Vichoudis, P.; Verlaat, B.; Zwalinski, L.; Bachmair, F.; Becker, R.; di Calafiori, D.; Casal, B.; Berger, P.; Djambazov, L.; Donega, M.; Grab, C.; Hits, D.; Hoss, J.; Kasieczka, G.; Lustermann, W.; Mangano, B.; Marionneau, M.; Martinez Ruiz del Arbol, P.; Masciovecchio, M.; Meinhard, M.; Perozzi, L.; Roeser, U.; Starodumov, A.; Tavolaro, V.; Wallny, R.; Zhu, D.; Amsler, C.; Bösiger, K.; Caminada, L.; Canelli, F.; Chiochia, V.; de Cosa, A.; Galloni, C.; Hreus, T.; Kilminster, B.; Lange, C.; Maier, R.; Ngadiuba, J.; Pinna, D.; Robmann, P.; Taroni, S.; Yang, Y.; Bertl, W.; Deiters, K.; Erdmann, W.; Horisberger, R.; Kaestli, H.-C.; Kotlinski, D.; Langenegger, U.; Meier, B.; Rohe, T.; Streuli, S.; Cussans, D.; Flacher, H.; Goldstein, J.; Grimes, M.; Jacob, J.; Seif El Nasr-Storey, S.; Cole, J.; Hoad, C.; Hobson, P.; Morton, A.; Reid, I. D.; Auzinger, G.; Bainbridge, R.; Dauncey, P.; Hall, G.; James, T.; Magnan, A.-M.; Pesaresi, M.; Raymond, D. M.; Uchida, K.; Garabedian, A.; Heintz, U.; Narain, M.; Nelson, J.; Sagir, S.; Speer, T.; Swanson, J.; Tersegno, D.; Watson-Daniels, J.; Chertok, M.; Conway, J.; Conway, R.; Flores, C.; Lander, R.; Pellett, D.; Ricci-Tam, F.; Squires, M.; Thomson, J.; Yohay, R.; Burt, K.; Ellison, J.; Hanson, G.; Olmedo, M.; Si, W.; Yates, B. R.; Gerosa, R.; Sharma, V.; Vartak, A.; Yagil, A.; Zevi Della Porta, G.; Dutta, V.; Gouskos, L.; Incandela, J.; Kyre, S.; Mullin, S.; Patterson, A.; Qu, H.; White, D.; Dominguez, A.; Bartek, R.; Cumalat, J. P.; Ford, W. T.; Jensen, F.; Johnson, A.; Krohn, M.; Leontsinis, S.; Mulholland, T.; Stenson, K.; Wagner, S. R.; Apresyan, A.; Bolla, G.; Burkett, K.; Butler, J. N.; Canepa, A.; Cheung, H. W. K.; Chramowicz, J.; Christian, D.; Cooper, W. E.; Deptuch, G.; Derylo, G.; Gingu, C.; Grünendahl, S.; Hasegawa, S.; Hoff, J.; Howell, J.; Hrycyk, M.; Jindariani, S.; Johnson, M.; Kahlid, F.; Lei, C. M.; Lipton, R.; Lopes De Sá, R.; Liu, T.; Los, S.; Matulik, M.; Merkel, P.; Nahn, S.; Prosser, A.; Rivera, R.; Schneider, B.; Sellberg, G.; Shenai, A.; Spiegel, L.; Tran, N.; Uplegger, L.; Voirin, E.; Berry, D. R.; Chen, X.; Ennesser, L.; Evdokimov, A.; Evdokimov, O.; Gerber, C. E.; Hofman, D. J.; Makauda, S.; Mills, C.; Sandoval Gonzalez, I. D.; Alimena, J.; Antonelli, L. J.; Francis, B.; Hart, A.; Hill, C. S.; Parashar, N.; Stupak, J.; Bortoletto, D.; Bubna, M.; Hinton, N.; Jones, M.; Miller, D. H.; Shi, X.; Tan, P.; Baringer, P.; Bean, A.; Khalil, S.; Kropivnitskaya, A.; Majumder, D.; Wilson, G.; Ivanov, A.; Mendis, R.; Mitchell, T.; Skhirtladze, N.; Taylor, R.; Anderson, I.; Fehling, D.; Gritsan, A.; Maksimovic, P.; Martin, C.; Nash, K.; Osherson, M.; Swartz, M.; Xiao, M.; Bloom, K.; Claes, D. R.; Fangmeier, C.; Gonzalez Suarez, R.; Monroy, J.; Siado, J.; Hahn, K.; Sevova, S.; Sung, K.; Trovato, M.; Bartz, E.; Gershtein, Y.; Halkiadakis, E.; Kyriacou, S.; Lath, A.; Nash, K.; Osherson, M.; Schnetzer, S.; Stone, R.; Walker, M.; Malik, S.; Norberg, S.; Ramirez Vargas, J. E.; Alyari, M.; Dolen, J.; Godshalk, A.; Harrington, C.; Iashvili, I.; Kharchilava, A.; Nguyen, D.; Parker, A.; Rappoccio, S.; Roozbahani, B.; Alexander, J.; Chaves, J.; Chu, J.; Dittmer, S.; McDermott, K.; Mirman, N.; Rinkevicius, A.; Ryd, A.; Salvati, E.; Skinnari, L.; Soffi, L.; Tao, Z.; Thom, J.; Tucker, J.; Zientek, M.; Akgün, B.; Ecklund, K. M.; Kilpatrick, M.; Nussbaum, T.; Zabel, J.; Betchart, B.; Covarelli, R.; Demina, R.; Hindrichs, O.; Petrillo, G.; Eusebi, R.; Osipenkov, I.; Perloff, A.; Ulmer, K. A.

    2017-06-01

    The upgrade of the LHC to the High-Luminosity LHC (HL-LHC) is expected to increase the LHC design luminosity by an order of magnitude. This will require silicon tracking detectors with a significantly higher radiation hardness. The CMS Tracker Collaboration has conducted an irradiation and measurement campaign to identify suitable silicon sensor materials and strip designs for the future outer tracker at the CMS experiment. Based on these results, the collaboration has chosen to use n-in-p type silicon sensors and focus further investigations on the optimization of that sensor type. This paper describes the main measurement results and conclusions that motivated this decision.

  15. Cavity perturbation techniques for measurement of the microwave conductivity and dielectric constant of a bulk semiconductor material.

    Science.gov (United States)

    Eldumiati, I. I.; Haddad, G. I.

    1972-01-01

    Cavity perturbation techniques offer a very sensitive and highly versatile means for studying the complex microwave conductivity of a bulk material. A knowledge of the cavity coupling factor in the absence of perturbation, together with the change in the reflected power and the cavity resonance frequency shift, are adequate for the determination of the material properties. This eliminates the need to determine the Q-factor change with perturbation which may lead to appreciable error, especially in the presence of mismatch loss. The measurement accuracy can also be improved by a proper choice of the cavity coupling factor prior to the perturbation.

  16. Fabrication of p-type conductivity in SnO{sub 2} thin films through Ga doping

    Energy Technology Data Exchange (ETDEWEB)

    Tsay, Chien-Yie, E-mail: cytsay@fcu.edu.tw; Liang, Shan-Chien

    2015-02-15

    Highlights: • P-type Ga-doped SnO{sub 2} semiconductor films were prepared by sol-gel spin coating. • Optical bandgaps of the SnO{sub 2}:Ga films are narrower than that of the SnO{sub 2} film. • SnO{sub 2}:Ga films exhibited p-type conductivity as Ga doping content higher than 10%. • A p-n heterojunction composed of p-type SnO{sub 2}:Ga and n-type ZnO:Al was fabricated. - Abstract: P-type transparent tin oxide (SnO{sub 2}) based semiconductor thin films were deposited onto alkali-free glass substrates by a sol-gel spin-coating method using gallium (Ga) as acceptor dopant. In this study, we investigated the influence of Ga doping concentration ([Ga]/[Sn] + [Ga] = 0%, 5%, 10%, 15%, and 20%) on the structural, optical and electrical properties of SnO{sub 2} thin films. XRD analysis results showed that dried Ga-doped SnO{sub 2} (SnO{sub 2}:Ga) sol-gel films annealed in oxygen ambient at 520 °C for 1 h exhibited only the tetragonal rutile phase. The average optical transmittance of as-prepared thin film samples was higher than 87.0% in the visible light region; the optical band gap energy slightly decreased from 3.92 eV to 3.83 eV with increases in Ga doping content. Hall effect measurement showed that the nature of conductivity of SnO{sub 2}:Ga thin films changed from n-type to p-type when the Ga doping level was 10%, and when it was at 15%, Ga-doped SnO{sub 2} thin films exhibited the highest mean hole concentration of 1.70 × 10{sup 18} cm{sup -3}. Furthermore, a transparent p-SnO{sub 2}:Ga (Ga doping level of 15%)/n-ZnO:Al (Al doping level of 2%) heterojunction was fabricated on alkali-free glass. The I-V curve measurement for the p-n heterojunction diode showed a typical rectifying characteristic with a forward turn-on voltage of 0.65 V.

  17. Semiconductor sensors

    Energy Technology Data Exchange (ETDEWEB)

    Hartmann, Frank, E-mail: frank.hartmann@cern.c [Institut fuer Experimentelle Kernphysik, KIT, Wolfgang-Gaede-Str. 1, Karlsruhe 76131 (Germany)

    2011-02-01

    Semiconductor sensors have been around since the 1950s and today, every high energy physics experiment has one in its repertoire. In Lepton as well as Hadron colliders, silicon vertex and tracking detectors led to the most amazing physics and will continue doing so in the future. This contribution tries to depict the history of these devices exemplarily without being able to honor all important developments and installations. The current understanding of radiation damage mechanisms and recent R and D topics demonstrating the future challenges and possible technical solutions for the SLHC detectors are presented. Consequently semiconductor sensor candidates for an LHC upgrade and a future linear collider are also briefly introduced. The work presented here is a collage of the work of many individual silicon experts spread over several collaborations across the world.

  18. Optically and electrically controlled circularly polarized emission from cholesteric liquid crystal materials doped with semiconductor quantum dots.

    Science.gov (United States)

    Bobrovsky, Alexey; Mochalov, Konstantin; Oleinikov, Vladimir; Sukhanova, Alyona; Prudnikau, Anatol; Artemyev, Mikhail; Shibaev, Valery; Nabiev, Igor

    2012-12-04

    Novel types of electro- and photoactive quantum dot-doped cholesteric materials have been engineered. UV-irradiation or electric field application allows one to control the degree of circular polarization and intensity of fluorescence emission by prepared quantum dot-doped liquid crystal films. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. p-Type CuYO{sub 2} as hydrogen photocathode

    Energy Technology Data Exchange (ETDEWEB)

    Trari, M.; Bouguelia, A.; Bessekhouad, Y. [Laboratoire de Stockage et de Valorisation des Energies Renouvelables, BP 32 El-Alia 16311, Algiers (Algeria)

    2006-01-23

    A new photochemical system based on a CuYO{sub 2} dispersion in aqueous S{sup 2-} or SO{sub 3}{sup 2-} solution as hole scavengers is proposed. The delafossite CuYO{sub 2}, doped with calcium, is a low p-type semiconductor with a hole mobility of 7.3x10{sup -7}m{sup 2}V{sup -1}s{sup -1}. The band gap is 3.50eV and the transition is directly allowed. The valence band edge, located at 5.23eV below vacuum, is made up from Cu-3d type typical of delafossite oxides. The flat band potential V{sub fb} (+0.17V{sub sce}) lies below the H{sub 2}O/H{sub 2} potential permitting a spontaneous H{sub 2}-formation under band gap illumination in aqueous S{sup 2-} or SO{sub 3}{sup 2-} electrolytes. p-CuYO{sub 2} loaded with n-Cu{sub 2}O exhibited a higher performance with a H{sub 2} evolution rate of 0.4cm{sup 3}h{sup -1} in 0.1MS{sup 2-} (pH 13.4). The decrease of photoactivity over time is due to the formation of yellow polysulfides S{sub n}{sup 2-} which compete with H{sub 2}O in the reduction process. (author)

  20. Device Physics of Narrow Gap Semiconductors

    CERN Document Server

    Chu, Junhao

    2010-01-01

    Narrow gap semiconductors obey the general rules of semiconductor science, but often exhibit extreme features of these rules because of the same properties that produce their narrow gaps. Consequently these materials provide sensitive tests of theory, and the opportunity for the design of innovative devices. Narrow gap semiconductors are the most important materials for the preparation of advanced modern infrared systems. Device Physics of Narrow Gap Semiconductors offers descriptions of the materials science and device physics of these unique materials. Topics covered include impurities and defects, recombination mechanisms, surface and interface properties, and the properties of low dimensional systems for infrared applications. This book will help readers to understand not only the semiconductor physics and materials science, but also how they relate to advanced opto-electronic devices. The last chapter applies the understanding of device physics to photoconductive detectors, photovoltaic infrared detector...

  1. Electronic processes in uniaxially stressed p-type germanium

    Energy Technology Data Exchange (ETDEWEB)

    Dubon, Jr., Oscar Danilo [Univ. of California, Berkeley, CA (United States)

    1996-02-01

    Effect of uniaxial stress on acceptor-related electronic processes in Ge single crystals doped with Ga, Be, and Cu were studied by Hall and photo-Hall effect measurements in conjunction with infrared spectroscopy. Stress dependence of hole lifetime in p-type Ge single crystals is used as a test for competing models of non-radiative capture of holes by acceptors. Photo-Hall effect shows that hole lifetime in Ga- and Be-doped Ge increases by over one order of magnitude with uniaxial stress at liq. He temps. Photo-Hall of Ge:Be shows a stress-induced change in the temperature dependence of hole lifetime. This is consistent with observed increase of responsivity of Ge:Ga detectors with uniaxial stress. Electronic properties of Ge:Cu are shown to change dramatically with uniaxial stress; the results provide a first explanation for the performance of uniaxially stressed, Cu-diffused Ge:Ga detectors which display a high conductivity in absence of photon signal and therefore have poor sensitivity.

  2. Fabrication and photoelectric properties of La-doped p-type ZnO nanofibers and crossed p-n homojunctions by electrospinning.

    Science.gov (United States)

    Zhang, H D; Yu, M; Zhang, J C; Sheng, C H; Yan, X; Han, W P; Liu, Y C; Chen, S; Shen, G Z; Long, Y Z

    2015-06-21

    La-doped p-type ZnO nanofibers were successfully synthesized by electrospinning, followed by calcination. The microstructure and morphology of the La-doped ZnO nanofibers were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy. The field effect curve of individual nanofibers confirms that the resulting La-doped ZnO fibers are p-type semiconductors. The doping mechanism is discussed. Furthermore, crossed p-n homojunction nanofibers were also prepared based on electrospun La-doped p-type ZnO and n-type pure ZnO fibers. The current-voltage curve shows the typical rectifying characteristic of a p-n homojunction device. The turn-on voltage appears at about 2.5 V under the forward bias and the reverse current is impassable.

  3. Fabrication and photoelectric properties of La-doped p-type ZnO nanofibers and crossed p-n homojunctions by electrospinning

    Science.gov (United States)

    Zhang, H. D.; Yu, M.; Zhang, J. C.; Sheng, C. H.; Yan, X.; Han, W. P.; Liu, Y. C.; Chen, S.; Shen, G. Z.; Long, Y. Z.

    2015-06-01

    La-doped p-type ZnO nanofibers were successfully synthesized by electrospinning, followed by calcination. The microstructure and morphology of the La-doped ZnO nanofibers were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy. The field effect curve of individual nanofibers confirms that the resulting La-doped ZnO fibers are p-type semiconductors. The doping mechanism is discussed. Furthermore, crossed p-n homojunction nanofibers were also prepared based on electrospun La-doped p-type ZnO and n-type pure ZnO fibers. The current-voltage curve shows the typical rectifying characteristic of a p-n homojunction device. The turn-on voltage appears at about 2.5 V under the forward bias and the reverse current is impassable.

  4. Bonds and bands in semiconductors

    CERN Document Server

    Phillips, Jim

    2009-01-01

    This classic work on the basic chemistry and solid state physics of semiconducting materials is now updated and improved with new chapters on crystalline and amorphous semiconductors. Written by two of the world's pioneering materials scientists in the development of semiconductors, this work offers in a single-volume an authoritative treatment for the learning and understanding of what makes perhaps the world's most important engineered materials actually work. Readers will find: --' The essential principles of chemical bonding, electron energy bands and their relationship to conductive and s

  5. SEMICONDUCTOR TECHNOLOGY Effects of the reciprocating parameters of the carrier on material removal rate and non-uniformity in CMP

    Science.gov (United States)

    Cailing, Wang; Renke, Kang; Zhuji, Jin; Dongming, Guo

    2010-12-01

    Based on the Preston equation, the mathematical model of the material removal rate (MRR), aiming at a line-orbit chemical mechanical polisher, is established. The MRR and the material removal non-uniformity (MRNU) are numerically calculated by MATLAB, and the effects of the reciprocating parameters on the MRR and the MRNU are discussed. It is shown that the smaller the inclination angle and the larger the amplitude, the higher the MRR and the lower the MRNU. The reciprocating speed of the carrier plays a minor role to improve the MRR and decrease the MRNU. The results provide a guide for the design of a polisher and the determination of a process in line-orbit chemical mechanical polishing.

  6. Air-stable conversion of separated carbon nanotube thin-film transistors from p-type to n-type using atomic layer deposition of high-κ oxide and its application in CMOS logic circuits.

    Science.gov (United States)

    Zhang, Jialu; Wang, Chuan; Fu, Yue; Che, Yuchi; Zhou, Chongwu

    2011-04-26

    Due to extraordinary electrical properties, preseparated, high purity semiconducting carbon nanotubes hold great potential for thin-film transistors (TFTs) and integrated circuit applications. One of the main challenges it still faces is the fabrication of air-stable n-type nanotube TFTs with industry-compatible techniques. Here in this paper, we report a novel and highly reliable method of converting the as-made p-type TFTs using preseparated semiconducting nanotubes into air-stable n-type transistors by adding a high-κ oxide passivation layer using atomic layer deposition (ALD). The n-type devices exhibit symmetric electrical performance compared with the p-type devices in terms of on-current, on/off ratio, and device mobility. Various factors affecting the conversion process, including ALD temperature, metal contact material, and channel length, have also been systematically studied by a series of designed experiments. A complementary metal-oxide-semiconductor (CMOS) inverter with rail-to-rail output, symmetric input/output behavior, and large noise margin has been further demonstrated. The excellent performance gives us the feasibility of cascading multiple stages of logic blocks and larger scale integration. Our approach can serve as the critical foundation for future nanotube-based thin-film macroelectronics.

  7. The development of p-type silicon detectors for the high radiation regions of the LHC

    CERN Document Server

    Hanlon, M D L

    1998-01-01

    This thesis describes the production and characterisation of silicon microstrip detectors and test structures on p-type substrates. An account is given of the production and full parameterisation of a p-type microstrip detector, incorporating the ATLAS-A geometry in a beam test. This detector is an AC coupled device incorporating a continuous p-stop isolation frame and polysilicon biasing and is typical of n-strip devices proposed for operation at the LHC. It was successfully read out using the FELix-128 analogue pipeline chip and a signal to noise (s/n) of 17+-1 is reported, along with a spatial resolution of 14.6+-0.2 mu m. Diode test structures were fabricated on both high resistivity float zone material and on epitaxial material and subsequently irradiated with 24 GeV protons at the CERN PS up to a dose of (8.22+-0.23) x 10 sup 1 sup 4 per cm sup 2. An account of the measurement program is presented along with results on the changes in the effective doping concentration (N sub e sub f sub f) with irradiat...

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

    Directory of Open Access Journals (Sweden)

    Goyal Prabal

    2016-01-01

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

  9. Semiconductor microcavity polaritons

    Energy Technology Data Exchange (ETDEWEB)

    Vinogradov, Evgenii A [Institute of Spectroscopy, Russian Academy of Sciences, Troitsk, Moscow region (Russian Federation)

    2002-12-31

    The optical properties of wide-gap semiconductor films on metal substrates were investigated experimentally by infrared spectroscopy, Raman scattering, and femtosecond spectroscopy techniques as well as theoretically in the framework of linear crystal optics. The optical spectra of such planar structures (microresonators) were shown to bear information on electromagnetic excitations of both the surface and the volume of the structure. The optical spectra are determined by the interaction of all dipole-active excitations of the component materials with the electromagnetic modes of the microresonator, which in turn are determined by the permittivities of each component material, microcavity (microresonator) thickness, and the experimental conditions. (reviews of topical problems)

  10. Modeling of anisotropic two-dimensional materials monolayer HfS{sub 2} and phosphorene metal-oxide semiconductor field effect transistors

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Jiwon [SEMATECH, 257 Fuller Rd #2200, Albany, New York 12203 (United States)

    2015-06-07

    Ballistic transport characteristics of metal-oxide semiconductor field effect transistors (MOSFETs) based on anisotropic two-dimensional materials monolayer HfS{sub 2} and phosphorene are explored through quantum transport simulations. We focus on the effects of the channel crystal orientation and the channel length scaling on device performances. Especially, the role of degenerate conduction band (CB) valleys in monolayer HfS{sub 2} is comprehensively analyzed. Benchmarking monolayer HfS{sub 2} with phosphorene MOSFETs, we predict that the effect of channel orientation on device performances is much weaker in monolayer HfS{sub 2} than in phosphorene due to the degenerate CB valleys of monolayer HfS{sub 2}. Our simulations also reveal that at 10 nm channel length scale, phosphorene MOSFETs outperform monolayer HfS{sub 2} MOSFETs in terms of the on-state current. However, it is observed that monolayer HfS{sub 2} MOSFETs may offer comparable, but a little bit degraded, device performances as compared with phosphorene MOSFETs at 5 nm channel length.

  11. Survey of semiconductor physics

    CERN Document Server

    Böer, Karl W

    1992-01-01

    Any book that covers a large variety of subjects and is written by one author lacks by necessity the depth provided by an expert in his or her own field of specialization. This book is no exception. It has been written with the encouragement of my students and colleagues, who felt that an extensive card file I had accumulated over the years of teaching solid state and semiconductor physics would be helpful to more than just a few of us. This file, updated from time to time, contained lecture notes and other entries that were useful in my research and permitted me to give to my students a broader spectrum of information than is available in typical textbooks. When assembling this material into a book, I divided the top­ ics into material dealing with the homogeneous semiconductor, the subject of the previously published Volume 1, and the inhomoge­ neous semiconductor, the subject of this Volume 2. In order to keep the book to a manageable size, sections of tutorial character which can be used as text for a g...

  12. Molecular semiconductors photoelectrical properties and solar cells

    CERN Document Server

    Rees, Ch

    1985-01-01

    During the past thirty years considerable efforts have been made to design the synthesis and the study of molecular semiconductors. Molecular semiconductors - and more generally molecular materials - involve interactions between individual subunits which can be separately synthesized. Organic and metallo-organic derivatives are the basis of most of the molecular materials. A survey of the literature on molecular semiconductors leaves one rather confused. It does seem to be very difficult to correlate the molecular structure of these semiconductors with their experimental electrical properties. For inorganic materials a simple definition delimits a fairly homogeneous family. If an inorganic material has a conductivity intermediate between that of an 12 1 1 3 1 1 insulator « 10- n- cm- ) and that of a metal (> 10 n- cm- ), then it is a semiconductor and will exhibit the characteristic properties of this family, such as junction formation, photoconductivity, and the photovoltaic effect. For molecular compounds,...

  13. Perovskite Sr-doped LaCrO3 as a new p-type transparent conducting oxide

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Hongliang; Du, Yingge; Papadogianni, Alexandra; Bierwagen, Oliver; Sallis, Shawn; Piper, Louis F. J.; Bowden, Mark E.; Shutthanandan, V.; Sushko, Petr; Chambers, Scott A.

    2015-09-16

    Transparent conducting oxides (TCOs) constitute a unique class of materials which combine the seemingly mutually exclusive properties of electrical conductivity and optical transparency in a single material. TCOs are useful for a wide range of applications including solar cells, displays, light emitting diodes and transparent electronics. Simple post-transition metal oxides such as ZnO, In2O3 and SnO2 are wide gap insulators in which the ionic character generates an oxygen 2p-derived valence band (VB) and a metal s-derived conduction band (CB), resulting in large optical band gaps (>3.0 eV) and excellent n-type conductivity when donor doped. In contrast, the development of efficient p-type TCOs remains a global materials challenge. Converting n-type oxides to p-type analogs by acceptor doping is extremely difficult and these materials display poor conductivity.

  14. Bulk Crystal Growth, and High-Resolution X-ray Diffraction Results of LiZnAs Semiconductor Material

    Science.gov (United States)

    Montag, Benjamin W.; Reichenberger, Michael A.; Sunder, Madhana; Ugorowski, Philip B.; Nelson, Kyle A.; Henson, Luke C.; McGregor, Douglas S.

    2017-08-01

    LiZnAs is being explored as a candidate for solid-state neutron detectors. The compact form, solid-state device would have greater efficiency than present day gas-filled 3He and 10BF3 detectors. Devices fabricated from LiZnAs having either natural Li (nominally 7.5% 6Li) or enriched 6Li (usually 95% 6Li) as constituent atoms may provide a material for compact high efficiency neutron detectors. The 6Li( n, t)4He reaction yields a total Q-value of 4.78 MeV, an energy larger than that of the 10B reaction, which can easily be identified above background radiations. LiZnAs material was synthesized by preparing equimolar portions of Li, Zn, and As sealed under vacuum (10-6 Torr) in quartz ampoules lined with boron nitride and subsequently reacted in a compounding furnace (Montag et al. in J Cryst Growth 412:103, 2015). The raw synthesized LiZnAs was purified by a static vacuum sublimation in quartz (Montag et al. in J Cryst Growth 438:99, 2016). Bulk crystalline LiZnAs ingots were grown from the purified material with a high-temperature Bridgman-style growth process described here. One of the largest LiZnAs ingots harvested was 9.6 mm in diameter and 4.2 mm in length. Samples were harvested from the ingot and were characterized for crystallinity using a Bruker AXS Inc. D8 AXS Inc. D2 CRYSO, energy dispersive x-ray diffractometer, and a Bruker AXS Inc. D8 DISCOVER, high-resolution x-ray diffractometer equipped with molybdenum radiation, Gobel mirror, four bounce germanium monochromator and a scintillation detector. The primary beam divergence was determined to be 0.004°, using a single crystal Si standard. The x-ray based characterization revealed that the samples nucleated in the (110) direction and a high-resolution open detector rocking curve recorded on the (220) LiZnAs yielded a full width at half maximum (FWHM) of 0.235°. Sectional pole figures using off-axis reflections of the (211) LiZnAs confirmed in-plane ordering, and also indicated the presence of multiple

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

    Science.gov (United States)

    Brown, Gail J.; Szmulowicz, Frank

    1995-04-01

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

  16. Polymer semiconductor crystals

    Directory of Open Access Journals (Sweden)

    Jung Ah Lim

    2010-05-01

    Full Text Available One of the long-standing challenges in the field of polymer semiconductors is to figure out how long interpenetrating and entangled polymer chains self-assemble into single crystals from the solution phase or melt. The ability to produce these crystalline solids has fascinated scientists from a broad range of backgrounds including physicists, chemists, and engineers. Scientists are still on the hunt for determining the mechanism of crystallization in these information-rich materials. Understanding the theory and concept of crystallization of polymer semiconductors will undoubtedly transform this area from an art to an area that will host a bandwagon of scientists and engineers. In this article we describe the basic concept of crystallization and highlight some of the advances in polymer crystallization from crystals to nanocrystalline fibers.

  17. Stretchable semiconductor elements and stretchable electrical circuits

    Science.gov (United States)

    Rogers, John A.; Khang, Dahl-Young; Menard, Etienne

    2009-07-07

    The invention provides methods and devices for fabricating printable semiconductor elements and assembling printable semiconductor elements onto substrate surfaces. Methods, devices and device components of the present invention are capable of generating a wide range of flexible electronic and optoelectronic devices and arrays of devices on substrates comprising polymeric materials. The present invention also provides stretchable semiconductor structures and stretchable electronic devices capable of good performance in stretched configurations.

  18. Semiconductor laser

    Energy Technology Data Exchange (ETDEWEB)

    Ito, K.; Shyuue, M.

    1982-09-25

    A distributed feedback semiconductor laser is proposed which generates several beams with equal wavelengths in different directions. For this purpose, 1 millimeter grooves are cut into the surface of an n-type conductance GaAs plate in three different directions; these grooves form a diffraction grating. The center of this plate has no grooves and is bombarded by an He/Ne laser beam. The diffraction gratings provide resonance properties and generate laser beams with wavelengths of 8850, 9000 and 9200 angstroms.

  19. Radioisotope space power generator. Annual report, July 1, 1975--September 30, 1976. [TPM-217 P-type selenides

    Energy Technology Data Exchange (ETDEWEB)

    Elsner, N.B.; Chin, J.; Staley, H.G.; Steeger, E.J.; Gantzel, P.K.

    1977-09-01

    TPM-217 P-type selenide usefulness in thermoelectric converters depends on its dimensional, electrical and thermal stability at high temperature and its compatibility with other converter component materials in a low pressure environment. Experimental efforts have been directed at determining: the vaporization behavior at 900/sup 0/C, the partial pressures of vaporizing species versus temperature, vapor suppression coatings, thermal expansion, dimensional stability, and the high temperature compatibility of TPM-217 with proposed end cap materials.

  20. Doping of organic semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    Luessem, B.; Riede, M.; Leo, K. [Institut fuer Angewandte Photophysik, TU Dresden (Germany)

    2013-01-15

    The understanding and applications of organic semiconductors have shown remarkable progress in recent years. This material class has been developed from being a lab curiosity to the basis of first successful products as small organic LED (OLED) displays; other areas of application such as OLED lighting and organic photovoltaics are on the verge of broad commercialization. Organic semiconductors are superior to inorganic ones for low-cost and large-area optoelectronics due to their flexibility, easy deposition, and broad variety, making tailor-made materials possible. However, electrical doping of organic semiconductors, i.e. the controlled adjustment of Fermi level that has been extremely important to the success of inorganic semiconductors, is still in its infancy. This review will discuss recent work on both fundamental principles and applications of doping, focused primarily to doping of evaporated organic layers with molecular dopants. Recently, both p- and n-type molecular dopants have been developed that lead to efficient and stable doping of organic thin films. Due to doping, the conductivity of the doped layers increases several orders of magnitude and allows for quasi-Ohmic contacts between organic layers and metal electrodes. Besides reducing voltage losses, doping thus also gives design freedom in terms of transport layer thickness and electrode choice. The use of doping in applications like OLEDs and organic solar cells is highlighted in this review. Overall, controlled molecular doping can be considered as key enabling technology for many different organic device types that can lead to significant improvements in efficiencies and lifetimes. (Copyright copyright 2013 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  1. Metal oxide semiconductor thin-film transistors for flexible electronics

    Science.gov (United States)

    Petti, Luisa; Münzenrieder, Niko; Vogt, Christian; Faber, Hendrik; Büthe, Lars; Cantarella, Giuseppe; Bottacchi, Francesca; Anthopoulos, Thomas D.; Tröster, Gerhard

    2016-06-01

    The field of flexible electronics has rapidly expanded over the last decades, pioneering novel applications, such as wearable and textile integrated devices, seamless and embedded patch-like systems, soft electronic skins, as well as imperceptible and transient implants. The possibility to revolutionize our daily life with such disruptive appliances has fueled the quest for electronic devices which yield good electrical and mechanical performance and are at the same time light-weight, transparent, conformable, stretchable, and even biodegradable. Flexible metal oxide semiconductor thin-film transistors (TFTs) can fulfill all these requirements and are therefore considered the most promising technology for tomorrow's electronics. This review reflects the establishment of flexible metal oxide semiconductor TFTs, from the development of single devices, large-area circuits, up to entirely integrated systems. First, an introduction on metal oxide semiconductor TFTs is given, where the history of the field is revisited, the TFT configurations and operating principles are presented, and the main issues and technological challenges faced in the area are analyzed. Then, the recent advances achieved for flexible n-type metal oxide semiconductor TFTs manufactured by physical vapor deposition methods and solution-processing techniques are summarized. In particular, the ability of flexible metal oxide semiconductor TFTs to combine low temperature fabrication, high carrier mobility, large frequency operation, extreme mechanical bendability, together with transparency, conformability, stretchability, and water dissolubility is shown. Afterward, a detailed analysis of the most promising metal oxide semiconducting materials developed to realize the state-of-the-art flexible p-type TFTs is given. Next, the recent progresses obtained for flexible metal oxide semiconductor-based electronic circuits, realized with both unipolar and complementary technology, are reported. In particular

  2. Wafer-fused semiconductor radiation detector

    Science.gov (United States)

    Lee, Edwin Y.; James, Ralph B.

    2002-01-01

    Wafer-fused semiconductor radiation detector useful for gamma-ray and x-ray spectrometers and imaging systems. The detector is fabricated using wafer fusion to insert an electrically conductive grid, typically comprising a metal, between two solid semiconductor pieces, one having a cathode (negative electrode) and the other having an anode (positive electrode). The wafer fused semiconductor radiation detector functions like the commonly used Frisch grid radiation detector, in which an electrically conductive grid is inserted in high vacuum between the cathode and the anode. The wafer-fused semiconductor radiation detector can be fabricated using the same or two different semiconductor materials of different sizes and of the same or different thicknesses; and it may utilize a wide range of metals, or other electrically conducting materials, to form the grid, to optimize the detector performance, without being constrained by structural dissimilarity of the individual parts. The wafer-fused detector is basically formed, for example, by etching spaced grooves across one end of one of two pieces of semiconductor materials, partially filling the grooves with a selected electrical conductor which forms a grid electrode, and then fusing the grooved end of the one semiconductor piece to an end of the other semiconductor piece with a cathode and an anode being formed on opposite ends of the semiconductor pieces.

  3. Power semiconductors

    CERN Document Server

    Kubát, M

    1984-01-01

    The book contains a summary of our knowledge of power semiconductor structures. It presents first a short historic introduction (Chap. I) as well as a brief selection of facts from solid state physics, in particular those related to power semiconductors (Chap. 2). The book deals with diode structures in Chap. 3. In addition to fundamental facts in pn-junction theory, the book covers mainly the important processes of power structures. It describes the emitter efficiency and function of microleaks (shunts). the p +p and n + n junctions, and in particular the recent theory of the pin, pvn and p1tn junctions, whose role appears to be decisive for the forward mode not only of diode structures but also of more complex ones. For power diode structures the reverse mode is the decisive factor in pn-junction breakdown theory. The presentation given here uses engineering features (the multiplication factor M and the experimentally detected laws for the volume and surface of crystals), which condenses the presentation an...

  4. Magnetic semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    Bihler, Christoph

    2009-04-15

    In this thesis we investigated in detail the properties of Ga{sub 1-x}Mn{sub x}As, Ga{sub 1-x}Mn{sub x}P, and Ga{sub 1-x}Mn{sub x}N dilute magnetic semiconductor thin films with a focus on the magnetic anisotropy and the changes of their properties upon hydrogenation. We applied two complementary spectroscopic techniques to address the position of H in magnetic semiconductors: (i) Electron paramagnetic resonance, which provides direct information on the symmetry of the crystal field of the Mn{sup 2+} atoms and (ii) x-ray absorption fine structure analysis which allows to probe the local crystallographic neighborhood of the absorbing Mn atom via analysing the fine structure at the Mn K absorption edge. Finally, we discussed the obstacles that have to be overcome to achieve Curie temperatures above the current maximum in Ga{sub 1-x}Mn{sub x}As of 185 K. Here, we outlined in detail the generic problem of the formation of precipitates at the example of Ge:MN. (orig.)

  5. Enhanced photovoltaic effect of ruthenium complex-modified graphene oxide with P-type conductivity

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Wei, E-mail: jj_zw_js@sina.com.cn; Bai, Huicong; Zhang, Yu; Sun, Ying; Lin, Shen; Liu, Jian; Yang, Qi; Song, Xi-Ming, E-mail: songlab@lnu.edu.cn

    2014-10-15

    A graphene oxide nanocomposite with bis(1,10-phenanthroline)(N-(2-aminoethyl)-4-(4-methyl-2,2-bipyridine-4-yl) formamide) ruthenium (Ru(phen){sub 2}(bpy-NH{sub 2})(PF{sub 6}){sub 2}), a ruthenium complex, was synthesized by amidation reaction between amino group of the ruthenium complex and carboxyl group of GO. The as-prepared Ru(II)–GO composite was characterized by infrared (IR) spectroscopy, X-ray photoelectron spectroscopy (XPS), ultraviolet–visible (UV–Vis) absorption spectra, fluorescence spectra, surface photovoltage (SPV) spectrum and transient photovoltage (TPV) technology. This nanocomposite showed a typical p-type character and an enhanced photovoltaic effect at long timescale of about 3 × 10{sup −3} s compared to GO alone. A reversible rise/decay of the photocurrent in response to the on/off illumination step was also observed in a photoelectrochemical cell of the Ru(II)–GO composite. The photocurrent response of the Ru(II)–GO film was remarkably higher than that of GO film. Therefore, this Ru(II)–GO composite is believed to be a promising p-type photoelectric conversion material for further photovoltaic applications. - Highlights: • A new dye-sensitized graphene oxide nanocomposite was reported. • A photo-induced charge transfer process in this nanocomposite was confirmed. • This composite showed a typical p-type conductivity. • This composite showed an enhanced photovoltaic effect at a long timescale.

  6. On the nature of ferromagnetism in dilute magnetic semiconductors: GaAs:Mn and GaP:Mn

    Energy Technology Data Exchange (ETDEWEB)

    Ivanov, V.A. E-mail: ivanov@uia.ua.ac.be; Krstajic, P.M.; Peeters, F.M.; Fleurov, V.; Kikoin, K

    2003-03-01

    On the basis of a simplified Hamiltonian for transition metal impurities in diluted magnetic semiconductors (DMS), the nature of ferromagnetism in p-type III-V DMS are investigated. Ferromagnetism is governed by the Anderson-Hubbard parameter for 3d electrons of Mn{sup 2+} and their strong hybridization with the hole carriers in the semiconducting medium. The origin of ferromagnetism in these materials has similarity with the Zener mechanism. From the energetically preferable parallel orientation of Mn spins the Curie temperature is calculated for GaAs:Mn.

  7. Semiconductor Laser Measurements Laboratory

    Data.gov (United States)

    Federal Laboratory Consortium — The Semiconductor Laser Measurements Laboratory is equipped to investigate and characterize the lasing properties of semiconductor diode lasers. Lasing features such...

  8. NbFeSb based p-type half-Heusler for power generation applications

    Science.gov (United States)

    Joshi, Giri; He, Ran; Engber, Michael; Samsonidze, Georgy; Pantha, Tej; Dahal, Ekraj; Dahal, Keshab; Yang, Jian; Lan, Yucheng; Kozinsky, Boris; Ren, Zhifeng

    2015-03-01

    We report a peak dimensionless figure-of-merit (ZT) of ~1 at 700 oC in nanostructured p-type Nb0.6Ti0.4FeSb0.95Sn0.05composition. Even though the power factor of the Nb0.6Ti0.4FeSb0.95Sn0.05 composition is improved by 25% in comparison to the previously reported p-type Hf0.44Zr0.44Ti0.12CoSb0.8Sn0.2, the ZT value is not increased due to a higher thermal conductivity. However, the higher power factor of the Nb0.6Ti0.4FeSb0.95Sn0.05 composition led to a 15% increase in power output of a thermoelectric device in comparison to a device made from the previous best material Hf0.44Zr0.44Ti0.12CoSb0.8Sn0.2. The n-type material used to make the unicouple device is the best reported nanostructured Hf0.25Zr0.75NiSn0.99Sb0.01 composition with the lowest hafnium (Hf) content. Both the p- and n-type nanostructured samples are prepared by ball milling the arc melted ingot and hot pressing the finely ground powders. Moreover, the raw material cost of the Nb0.6Ti0.4FeSb0.95Sn0.05 composition is more than six times lower compared to the cost of the previous best p-type Hf0.44Zr0.44Ti0.12CoSb0.8Sn0.2. This cost reduction is crucial for these materials to be used in large-scale quantities for vehicle and industrial waste heat recovery applications. DOE:DE-EE0004840.

  9. P-type polymer-based Ag2S atomic switch for “tug of war” operation

    Science.gov (United States)

    Lutz, Carolin; Hasegawa, Tsuyoshi; Tsuchiya, Takashi; Adelsberger, Christoph; Hayakawa, Ryoma; Chikyow, Toyohiro

    2017-06-01

    The Ag2S gap-type atomic switch based “tug of war” device is a promising element for building a new type of CMOS free neuromorphic computer-hardware. Since Ag+ cations are reduced during operation of the device, it was thought that the gap-material should be a n-type polymer. In this study, we revealed that the polymer bithiophene-oligoethyleneoxide (BTOE) doped poly(ethylene oxide) (PEO), which was used as gap-material in the first demonstration of the “tug of war”, is a p-type polymer. For this we used impedance spectroscopy and transistor measurements. We elaborate on how the electrochemical processes in the “tug of war” devices could be explained in the case of p-type conductive gap-materials.

  10. Wide band gap p-type windows by CBD and SILAR methods

    Energy Technology Data Exchange (ETDEWEB)

    Sankapal, B.R.; Goncalves, E.; Ennaoui, A.; Lux-Steiner, M.Ch

    2004-03-22

    Chemical deposition methods, namely, chemical bath deposition (CBD) and successive ionic layer adsorption and reaction (SILAR) have been used to deposit wide band gap p-type CuI and CuSCN thin films at room temperature (25 deg. C) in aqueous medium. Growth of these films requires the use of Cu (I) cations as a copper ions source. This is achieved by complexing Cu (II) ions using Na{sub 2}S{sub 2}O{sub 3}. The anion sources are either KI as iodine or KSCN as thiocyanide ions for CuI and CuSCN films, respectively. The preparative parameters are optimized with the aim to use these p-type materials as windows for solar cells. Different substrates are used, namely: glass, fluorine doped tin oxide coated glass and CuInS{sub 2} (CIS). X-ray diffraction, scanning electron microscopy, atomic force microscopy and optical absorption spectroscopy are used for structural, surface morphological and optical studies, and the results are discussed.

  11. Carrier induced local moment magnetization in p-type Sn1-xMnxTe

    Science.gov (United States)

    Behera, Sashi S.; Tripathi, Pratibha; Nayak, Sanjeev K.; Tripathi, Gouri S.

    2017-08-01

    We derive a theory of carrier induced local moment magnetization of p-type Sn1-xMnxTe based on the Hubbard model, k → · π → electronic structure method (k → is the electronic wave vector and π → is the relativistic momentum operator) and the statistical paramagnetic approach for the localized moments. The Hubbard model is used to derive an internal exchange magnetic field. The difference in exchange self-energy is expressed in terms of an internal exchange field that is proportional to the parameter U, the onsite Coulomb repulsion, and the spin-density of carriers. In the present theory, the k → · π → + U model is integrated with the statistical paramagnetic theory for localized spins, which is then solved in a self-consistent manner by adding the exchange field to the applied field. The technique is applied to study the magnetic properties of p-type Sn1-xMnxTe, an important material for spintronics devices. The local moment magnetization calculated using the total magnetic field self-consistently agrees with the experimental observations. Magnetization and the exchange field studied as functions of the applied field, temperature and carrier concentration yield results on expected lines. Ours is a mechanism that is different from the RKKY interaction, normally invoked for carrier induced ferromagnetism and is thus a novelty.

  12. Porous and Nanoporous Semiconductors and Emerging Applications

    Directory of Open Access Journals (Sweden)

    Helmut Föll

    2006-01-01

    Full Text Available Pores in single-crystalline semiconductors can be produced in a wide range of geometries and morphologies, including the “nanometer” regime. Porous semiconductors may have properties completely different from the bulk, and metamaterials with, for example, optical properties not encountered in natural materials are emerging. Possible applications of porous semiconductors include various novel sensors, but also more “exotic” uses as, for example, high explosives or electrodes for micro-fuel cells. The paper briefly reviews pore formation (including more applied aspects of large area etching, properties of porous semiconductors, and emerging applications.

  13. Emission and Absorption Entropy Generation in Semiconductors

    DEFF Research Database (Denmark)

    Reck, Kasper; Varpula, Aapo; Prunnila, Mika

    2013-01-01

    While emission and absorption entropy generation is well known in black bodies, it has not previously been studied in semiconductors, even though semiconductors are widely used for solar light absorption in modern solar cells [1]. We present an analysis of the entropy generation in semiconductor...... materials due to emission and absorption of electromagnetic radiation. It is shown that the emission and absorption entropy generation reduces the fundamental limit on the efficiency of any semiconductor solar cell even further than the Landsberg limit. The results are derived from purely thermodynamical...

  14. Reliability tests of electroless barriers against copper diffusion under bias-temperature stress with n- and p-type substrates

    Science.gov (United States)

    Ueno, Kazuyoshi; Fujishima, Shota; Yamashita, Makoto; Mitsumori, Akiyoshi

    2016-05-01

    To investigate the similarity and difference of substrate conduction type in the time-dependent dielectric breakdown (TDDB) tests for the barrier integrity against Cu diffusion under bias-temperature stress (BTS), the TDDB reliability of electroless NiB and CoWP/NiB was determined by metal oxide semiconductor (MOS) structures on n-type Si (n-Si) substrates, and the test results were compared with those using p-type Si (p-Si) substrates. The TDDB results and mechanism were observed to be qualitatively the same as Cu diffusion for both conduction types. However, the TDDB lifetime using p-Si was found to be potentially shorter because of the reverse bias conditions than that using n-Si under the forward bias conditions.

  15. Identifying individual n- and p-type ZnO nanowires by the output voltage sign of piezoelectric nanogenerator

    Energy Technology Data Exchange (ETDEWEB)

    Lin, S S; Song, J H; Wang, Z L [School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, GA 30332 (United States); Lu, Y F, E-mail: zlwang@gatech.ed [State Key Laboratory of Silicon Materials, Zhejiang University, Hangzhou, 310027 (China)

    2009-09-09

    Based on a comparative study between the piezoelectric outputs of n-type nanowires (NWs) and n-core/p-shell NWs along with the previous study (Lu et al 2009 Nano. Lett. 9 1223), we demonstrate a one-step technique for identifying the conductivity type of individual ZnO nanowires (NWs) based on the output of a piezoelectric nanogenerator without destroying the sample. A negative piezoelectric output voltage indicates an NW is n-type and it appears after the tip scans across the center of the NW, while a positive output voltage reveals p-type conductivity and it appears before the tip scans across the central line of the NW. This atomic force microscopy based technique is reliable for statistically mapping the majority carrier type in ZnO NWs arrays. The technique may also be applied to other wurtzite semiconductors, such as GaN, CdS and ZnS.

  16. Characterization of micro-strip detectors made with high resistivity n- and p-type Czochralski silicon

    Energy Technology Data Exchange (ETDEWEB)

    Macchiolo, A. [INFN and Universita degli Studi di Florence (Italy)]. E-mail: Anna.Macchiolo@fi.infn.it; Borrello, L. [INFN and Universita degli Studi di Pisa (Italy); Boscardin, M. [ITC-IRST Trento, Povo, Trento (Italy); Bruzzi, M. [INFN and Universita degli Studi di Florence (Italy); Creanza, D. [INFN and Dipartimento Interateneo di Fisica, Bari (Italy); Dalla Betta, G.-F. [ITC-IRST Trento, Povo, Trento (Italy); DePalma, M. [INFN and Dipartimento Interateneo di Fisica, Bari (Italy); Focardi, E. [INFN and Universita degli Studi di Florence (Italy); Manna, N. [INFN and Dipartimento Interateneo di Fisica, Bari (Italy); Menichelli, D. [INFN and Universita degli Studi di Florence (Italy); Messineo, A. [INFN and Universita degli Studi di Pisa (Italy); Piemonte, C. [ITC-IRST Trento, Povo, Trento (Italy); Radicci, V. [INFN and Dipartimento Interateneo di Fisica, Bari (Italy); Ronchin, S. [ITC-IRST Trento, Povo, Trento (Italy); Scaringella, M. [INFN and Universita degli Studi di Florence (Italy); Segneri, G. [INFN and Universita degli Studi di Pisa (Italy); Sentenac, D. [INFN and Universita degli Studi di Pisa (Italy); Zorzi, N. [ITC-IRST Trento, Povo, Trento (Italy)

    2007-04-01

    The results of the pre- and post-irradiation characterization of n- and p-type magnetic Czochralski silicon micro-strip sensors are reported. This work has been carried out within the INFN funded SMART project aimed at the development of radiation-hard semiconductor detectors for the luminosity upgrade of the large Hadron collider (LHC). The detectors have been fabricated at ITC-IRST (Trento, Italy) on 4 in wafers and the layout contains 10 mini-sensors. The devices have been irradiated with 24 GeV/c and 26 MeV protons in two different irradiation campaigns up to an equivalent fluence of 3.4x10{sup 15} 1-MeV n/cm{sup 2}. The post-irradiation results show an improved radiation hardness of the magnetic Czochralski mini-sensors with respect to the reference float-zone sample.

  17. Identifying individual n- and p-type ZnO nanowires by the output voltage sign of piezoelectric nanogenerator

    KAUST Repository

    Lin, S S

    2009-08-18

    Based on a comparative study between the piezoelectric outputs of n-type nanowires (NWs) and n-core/p-shell NWs along with the previous study (Lu et al 2009 Nano. Lett. 9 1223), we demonstrate a one-step technique for identifying the conductivity type of individual ZnO nanowires (NWs) based on the output of a piezoelectric nanogenerator without destroying the sample. A negative piezoelectric output voltage indicates an NW is n-type and it appears after the tip scans across the center of the NW, while a positive output voltage reveals p-type conductivity and it appears before the tip scans across the central line of the NW. This atomic force microscopy based technique is reliable for statistically mapping the majority carrier type in ZnO NWs arrays. The technique may also be applied to other wurtzite semiconductors, such as GaN, CdS and ZnS. © 2009 IOP Publishing Ltd.

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

    Science.gov (United States)

    Yu, Eunseon; Cho, Seongjae

    2016-11-01

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

  19. Fabrication and Characterization of a Single Hole Transistor in p-type GaAs/AlGaAs Heterostructures

    Energy Technology Data Exchange (ETDEWEB)

    Tracy, Lisa A [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States); Reno, John L. [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States); Hargett, Terry W. [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States)

    2015-09-01

    Most spin qubit research to date has focused on manipulating single electron spins in quantum dots. However, hole spins are predicted to have some advantages over electron spins, such as reduced coupling to host semiconductor nuclear spins and the ability to control hole spins electrically using the large spin-orbit interaction. Building on recent advances in fabricating high-mobility 2D hole systems in GaAs/AlGaAs heterostructures at Sandia, we fabricate and characterize single hole transistors in GaAs. We demonstrate p-type double quantum dot devices with few-hole occupation, which could be used to study the physics of individual hole spins and control over coupling between hole spins, looking towards eventual applications in quantum computing. Intentionally left blank

  20. Coincident site lattice-matched growth of semiconductors on substrates using compliant buffer layers

    Science.gov (United States)

    Norman, Andrew

    2016-08-23

    A method of producing semiconductor materials and devices that incorporate the semiconductor materials are provided. In particular, a method is provided of producing a semiconductor material, such as a III-V semiconductor, on a silicon substrate using a compliant buffer layer, and devices such as photovoltaic cells that incorporate the semiconductor materials. The compliant buffer material and semiconductor materials may be deposited using coincident site lattice-matching epitaxy, resulting in a close degree of lattice matching between the substrate material and deposited material for a wide variety of material compositions. The coincident site lattice matching epitaxial process, as well as the use of a ductile buffer material, reduce the internal stresses and associated crystal defects within the deposited semiconductor materials fabricated using the disclosed method. As a result, the semiconductor devices provided herein possess enhanced performance characteristics due to a relatively low density of crystal defects.

  1. High pressure semiconductor physics I

    CERN Document Server

    Willardson, R K; Paul, William; Suski, Tadeusz

    1998-01-01

    Since its inception in 1966, the series of numbered volumes known as Semiconductors and Semimetals has distinguished itself through the careful selection of well-known authors, editors, and contributors. The "Willardson and Beer" Series, as it is widely known, has succeeded in publishing numerous landmark volumes and chapters. Not only did many of these volumes make an impact at the time of their publication, but they continue to be well-cited years after their original release. Recently, Professor Eicke R. Weber of the University of California at Berkeley joined as a co-editor of the series. Professor Weber, a well-known expert in the field of semiconductor materials, will further contribute to continuing the series' tradition of publishing timely, highly relevant, and long-impacting volumes. Some of the recent volumes, such as Hydrogen in Semiconductors, Imperfections in III/V Materials, Epitaxial Microstructures, High-Speed Heterostructure Devices, Oxygen in Silicon, and others promise indeed that this tra...

  2. Effects of p-type nickel oxide semiconductor and gold bilayer on highly efficient polymer solar cell

    Energy Technology Data Exchange (ETDEWEB)

    Park, Jeong Woo [R and D Center, Samsung Corning Precision Materials Co., Ltd., Asan (Korea, Republic of); Shin, Sang Chul; Shin, Jae Won [Dept. of Electronics and Electrical Engineering, Dongguk University-SeouL, Seoul (Korea, Republic of)

    2016-10-15

    In this study, we report a new hole-collecting interlayer (HCI) comprising NiO/Au/poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) for poly(3-hexylthiophene) (P3HT) and phenyl-C61-butyric acid methyl ester (PCBM)-based polymer solar cells (PSCs). The insertion of a bilayer of NiO/Au between indium tin oxide (ITO) and PEDOT:PSS improves the photocurrent generation of the PSCs. The NiO layer provides an intermediate step energy level between ITO and PEDOT:PSS, leading to enhanced hole collection. The ultrathin Au induces a surface plasmon resonance effect, allowing more photons to be absorbed by the photoactive layer and improving the hole-collecting properties by planarizing and doping the NiO. The PSCs with the NiO/Au/PEDOT:PSS HCIs yield a power-conversion efficiency of 3.9 ± 0.2%, which is approximately 15% higher than that of PSCs with a PEDOT:PSS-only HCI, under a simulated air mass 1.5 global (G) 100 mW/cm{sup 2} illumination.

  3. Ultraviolet light-emitting diodes with polarization-doped p-type layer

    Science.gov (United States)

    Hu, Wenxiao; Qin, Ping; Song, Weidong; Zhang, Chongzhen; Wang, Rupeng; Zhao, Liangliang; Xia, Chao; Yuan, Songyang; Yin, Yian; Li, Shuti

    2016-09-01

    We report ultraviolet light emitting diode (LEDs) with polarization doped p-type layer. Fabricated LEDs with polarization doped p-type layer exhibited reduced forward voltage and enhanced light output power, compared to those with traditional p-type AlGaN layer. The improvement is attributed to improved hole concentration and the smooth valence band by the polarization enhanced p-type doping. Our simulated results reveal that this p-type layer can further enhance the performance of ultraviolet LEDs by removing the electron blocking layer (EBL).

  4. Broad-range modulation of light emission in two-dimensional semiconductors by molecular physisorption gating.

    Science.gov (United States)

    Tongay, Sefaattin; Zhou, Jian; Ataca, Can; Liu, Jonathan; Kang, Jeong Seuk; Matthews, Tyler S; You, Long; Li, Jingbo; Grossman, Jeffrey C; Wu, Junqiao

    2013-06-12

    In the monolayer limit, transition metal dichalcogenides become direct-bandgap, light-emitting semiconductors. The quantum yield of light emission is low and extremely sensitive to the substrate used, while the underlying physics remains elusive. In this work, we report over 100 times modulation of light emission efficiency of these two-dimensional semiconductors by physical adsorption of O2 and/or H2O molecules, while inert gases do not cause such effect. The O2 and/or H2O pressure acts quantitatively as an instantaneously reversible "molecular gating" force, providing orders of magnitude broader control of carrier density and light emission than conventional electric field gating. Physi-sorbed O2 and/or H2O molecules electronically deplete n-type materials such as MoS2 and MoSe2, which weakens electrostatic screening that would otherwise destabilize excitons, leading to the drastic enhancement in photoluminescence. In p-type materials such as WSe2, the molecular physisorption results in the opposite effect. Unique and universal in two-dimensional semiconductors, the effect offers a new mechanism for modulating electronic interactions and implementing optical devices.

  5. Band structure of semiconductors

    CERN Document Server

    Tsidilkovski, I M

    2013-01-01

    Band Structure of Semiconductors provides a review of the theoretical and experimental methods of investigating band structure and an analysis of the results of the developments in this field. The book presents the problems, methods, and applications in the study of band structure. Topics on the computational methods of band structure; band structures of important semiconducting materials; behavior of an electron in a perturbed periodic field; effective masses and g-factors for the most commonly encountered band structures; and the treatment of cyclotron resonance, Shubnikov-de Haas oscillatio

  6. Physics of Organic Semiconductors

    CERN Document Server

    Brütting, Wolfgang

    2005-01-01

    Filling the gap in the literature currently available, this book presents an overview of our knowledge of the physics behind organic semiconductor devices. Contributions from 18 international research groups cover various aspects of this field, ranging from the growth of organic layers and crystals, their electronic properties at interfaces, their photophysics and electrical transport properties to the application of these materials in such different devices as organic field-effect transistors, photovoltaic cells and organic light-emitting diodes. From the contents:. * Excitation Dynamics in O

  7. X-ray absorption spectroscopy of semiconductors

    CERN Document Server

    Ridgway, Mark

    2015-01-01

    X-ray Absorption Spectroscopy (XAS) is a powerful technique with which to probe the properties of matter, equally applicable to the solid, liquid and gas phases. Semiconductors are arguably our most technologically-relevant group of materials given they form the basis of the electronic and photonic devices that now so widely permeate almost every aspect of our society. The most effective utilisation of these materials today and tomorrow necessitates a detailed knowledge of their structural and vibrational properties. Through a series of comprehensive reviews, this book demonstrates the versatility of XAS for semiconductor materials analysis and presents important research activities in this ever growing field. A short introduction of the technique, aimed primarily at XAS newcomers, is followed by twenty independent chapters dedicated to distinct groups of materials. Topics span dopants in crystalline semiconductors and disorder in amorphous semiconductors to alloys and nanometric material as well as in-sit...

  8. Heteroepitaxy of semiconductors theory, growth, and characterization

    CERN Document Server

    Ayers, John E

    2007-01-01

    Heteroepitaxy has evolved rapidly in recent years. With each new wave of material/substrate combinations, our understanding of how to control crystal growth becomes more refined. Most books on the subject focus on a specific material or material family, narrowly explaining the processes and techniques appropriate for each. Surveying the principles common to all types of semiconductor materials, Heteroepitaxy of Semiconductors: Theory, Growth, and Characterization is the first comprehensive, fundamental introduction to the field. This book reflects our current understanding of nucleation, growth modes, relaxation of strained layers, and dislocation dynamics without emphasizing any particular material. Following an overview of the properties of semiconductors, the author introduces the important heteroepitaxial growth methods and provides a survey of semiconductor crystal surfaces, their structures, and nucleation. With this foundation, the book provides in-depth descriptions of mismatched heteroepitaxy and la...

  9. Semiconductors for solar cell applications

    Energy Technology Data Exchange (ETDEWEB)

    Moeller, H.J. (Case Western Reserve Univ., Cleveland, OH (United States). Dept. of Materials Science and Engineering)

    1991-01-01

    This review covers the historical background of the solar cell development, the physical principles of photovoltaic energy conversion, technology of solar cell devices and the structural and physical properties of lattice defects in semiconductors. Single crystal and polycrystalline silicon, single crystal and epitaxial gallium arsenide, polycrystalline thin films and amorphous thin films are discussed in detail. Semiconductors have emerged as the most promising group of materials which can convert sunlight directly into electrical energy. They utilize the fundamental physical process that a photon that penetrates into the semiconductor and is absorbed can generate electron-hole pairs. Because of their opposite charges they can be separated by an internal electrical field and collected at two contacts thus giving rise to a voltage and photocurrent if the two contacts are connected externally. In semiconductors internal electric fields occur in connection with space charges at junctions and a variety of technological concepts are used to produce a built-in voltage. The most widely used device principle is the operation of a solar cell as a diode or p-n junction. Alternative concepts are heterojunction devices where the materials on either side of the junction are different semiconductors. (author).

  10. High performance printed N and P-type OTFTs enabling digital and analog complementary circuits on flexible plastic substrate

    Science.gov (United States)

    Jacob, S.; Abdinia, S.; Benwadih, M.; Bablet, J.; Chartier, I.; Gwoziecki, R.; Cantatore, E.; van Roermund, A. H. M.; Maddiona, L.; Tramontana, F.; Maiellaro, G.; Mariucci, L.; Rapisarda, M.; Palmisano, G.; Coppard, R.

    2013-06-01

    This paper presents a printed organic complementary technology on flexible plastic substrate with high performance N and P-type Organic Thin Film Transistors (OTFTs), based on small-molecule organic semiconductors in solution. Challenges related to the integration of both OTFT types in a common complementary flow are addressed, showing the importance of surface treatments. Stability on single devices and on an elementary complementary digital circuit (ring oscillator) is studied, demonstrating that a robust and reliable flow with high electrical performances can be established for printed organic devices. These devices are used to manufacture several analog and digital building blocks. The design is carried out using a model specifically developed for this technology, and taking into account the parametric variability. High-frequency measurements of printed envelope detectors show improved speed performance, resulting from the high mobility of the OTFTs. In addition, a compact dynamic flip-flop and a low-offset comparator are demonstrated, thanks to availability of both n-type and p-type OTFTs in the technology. Measurement results are in good agreement with the simulations. The circuits presented establish a complete library of building blocks for the realization of a printed RFID tag.

  11. Perovskite LaRhO{sub 3} as a p-type active layer in oxide photovoltaics

    Energy Technology Data Exchange (ETDEWEB)

    Nakamura, Masao, E-mail: masao.nakamura@riken.jp; Krockenberger, Yoshiharu [RIKEN Center for Emergent Matter Science (CEMS), Wako 351-0198 (Japan); Fujioka, Jun [Department of Applied Physics and Quantum-Phase Electronics Center (QPEC), University of Tokyo, Tokyo 113-8656 (Japan); Kawasaki, Masashi; Tokura, Yoshinori [RIKEN Center for Emergent Matter Science (CEMS), Wako 351-0198 (Japan); Department of Applied Physics and Quantum-Phase Electronics Center (QPEC), University of Tokyo, Tokyo 113-8656 (Japan)

    2015-02-16

    Perovskite-type transition-metal oxides have a wide variety of physical properties and triggered intensive research on functional devices in the form of heteroepitaxial junctions. However, there is a missing component that is a p-type conventional band semiconductor. LaRhO{sub 3} (LRO) is one of very few promising candidates having its bandgap between filled t{sub 2g} and empty e{sub g} of Rh in low-spin state, but there has been no report on the synthesis of large-size single crystals or thin films. Here, we report on the junction properties of single-crystalline thin films of LRO grown on (110) oriented Nb-doped SrTiO{sub 3} substrates. The external quantum efficiency of the photo-electron conversion exceeds 1% in the visible-light region due to the wide depletion layer and long diffusion length of minority carriers in LRO. Clear indication of p-type band semiconducting character in a perovskite oxide of LRO will pave a way to explore oxide electronics of perovskite heterostructures.

  12. Nanostructured p-type CZTS thin films prepared by a facile solution process for 3D p-n junction solar cells.

    Science.gov (United States)

    Park, Si-Nae; Sung, Shi-Joon; Sim, Jun-Hyoung; Yang, Kee-Jeong; Hwang, Dae-Kue; Kim, JunHo; Kim, Gee Yeong; Jo, William; Kim, Dae-Hwan; Kang, Jin-Kyu

    2015-07-07

    Nanoporous p-type semiconductor thin films prepared by a simple solution-based process with appropriate thermal treatment and three-dimensional (3D) p-n junction solar cells fabricated by depositing n-type semiconductor layers onto the nanoporous p-type thin films show considerable photovoltaic performance compared with conventional thin film p-n junction solar cells. Spin-coated p-type Cu2ZnSnS4 (CZTS) thin films prepared using metal chlorides and thiourea show unique nanoporous thin film morphology, which is composed of a cluster of CZTS nanograins of 50-500 nm, and the obvious 3D p-n junction structure is fabricated by the deposition of n-type CdS on the nanoporous CZTS thin films by chemical bath deposition. The photovoltaic properties of 3D p-n junction CZTS solar cells are predominantly affected by the scale of CZTS nanograins, which is easily controlled by the sulfurization temperature of CZTS precursor films. The scale of CZTS nanograins determines the minority carrier transportation within the 3D p-n junction between CZTS and CdS, which are closely related with the photocurrent of series resistance of 3D p-n junction solar cells. 3D p-n junction CZTS solar cells with nanograins below 100 nm show power conversion efficiency of 5.02%, which is comparable with conventional CZTS thin film solar cells.

  13. Suitability of integrated protection diodes from diverse semiconductor technologies

    NARCIS (Netherlands)

    Wanum, van Maurice; Lebouille, Tom; Visser, Guido; Vliet, van Frank E.

    2009-01-01

    Abstract In this article diodes from three different semiconductor technologies are compared based on their suitability to protect a receiver. The semiconductor materials involved are silicon, gallium arsenide and gallium nitride. The diodes in the diverse semiconductor technologies themselves are c

  14. Suitability of integrated protection diodes from diverse semiconductor technologies

    NARCIS (Netherlands)

    Wanum, M. van; Lebouille, T.T.N.; Visser, G.C.; Vliet, F.E. van

    2009-01-01

    In this article diodes from three different semiconductor technologies are compared based on their suitability to protect a receiver. The semiconductor materials involved are Silicon, Gallium Arsenide and Gallium Nitride. The diodes in the diverse semiconductor technologies themselves are close in p

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

    Science.gov (United States)

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

    2017-04-01

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

  16. Improved thermoelectric efficiency in p-type ZnSb through Zn deficiency

    Science.gov (United States)

    Guo, Qilong; Luo, Sijun

    2015-12-01

    We herein report a feasible approach to improve the thermoelectric performance of p-type ZnSb compound by Zn content regulation. It is found that Zn vacancies formed by Zn deficiency not only efficiently enhance the electrical conductivity due to the improved hole concentration but also markedly lower the lattice thermal conductivity on account of the reinforced point defect scattering of phonons. The ZnSb compound with a nominal 3 mol.% Zn deficiency shows a maximum thermoelectric figure of merit ZT of 0.8 at 700 K which is a 60% improvement over the pristine sample. The strategies of further enhancing the performance of ZnSb-based material have been discussed.

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

    Science.gov (United States)

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

    2017-04-01

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

  18. Semiconductor laser. Halbleiterlaser

    Energy Technology Data Exchange (ETDEWEB)

    Wuenstel, K.; Gohla, B.; Tegude, F.; Luz, G.; Hildebrand, O.

    1987-08-27

    A highly modulable semiconductor laser and a process for its manufacture are described. The semiconductor laser has a substrate, a stack of semiconductor layers and electrical contacts. To reduce the capacity, the width of the stack of semiconductor layers is reduced at the sides by anisotropic etching. The electrical contacts are situated on the same side of the substrate and are applied in the same stage of the process. The semiconductor laser is suitable for monolithic integration in other components.

  19. Manipulating semiconductor colloidal stability through doping.

    Science.gov (United States)

    Fleharty, Mark E; van Swol, Frank; Petsev, Dimiter N

    2014-10-10

    The interface between a doped semiconductor material and electrolyte solution is of considerable fundamental interest, and is relevant to systems of practical importance. Both adjacent domains contain mobile charges, which respond to potential variations. This is exploited to design electronic and optoelectronic sensors, and other enabling semiconductor colloidal materials. We show that the charge mobility in both phases leads to a new type of interaction between semiconductor colloids suspended in aqueous electrolyte solutions. This interaction is due to the electrostatic response of the semiconductor interior to disturbances in the external field upon the approach of two particles. The electrostatic repulsion between two charged colloids is reduced from the one governed by the charged groups present at the particles surfaces. This type of interaction is unique to semiconductor particles and may have a substantial effect on the suspension dynamics and stability.

  20. 2010 Defects in Semiconductors GRC

    Energy Technology Data Exchange (ETDEWEB)

    Shengbai Zhang

    2011-01-06

    Continuing its tradition of excellence, this Gordon Conference will focus on research at the forefront of the field of defects in semiconductors. The conference will have a strong emphasis on the control of defects during growth and processing, as well as an emphasis on the development of novel defect detection methods and first-principles defect theories. Electronic, magnetic, and optical properties of bulk, thin film, and nanoscale semiconductors will be discussed in detail. In contrast to many conferences, which tend to focus on specific semiconductors, this conference will deal with point and extended defects in a broad range of electronic materials. This approach has proved to be extremely fruitful for advancing fundamental understanding in emerging materials such as wide-band-gap semiconductors, oxides, sp{sup 2} carbon based-materials, and photovoltaic/solar cell materials, and in understanding important defect phenomena such as doping bottleneck in nanostructures and the diffusion of defects and impurities. The program consists of about twenty invited talks and a number of contributed poster sessions. The emphasis should be on work which has yet to be published. The large amount of discussion time provides an ideal forum for dealing with topics that are new and/or controversial.

  1. Semiconductor technology program: Progress briefs

    Science.gov (United States)

    Galloway, K. F.; Scace, R. I.; Walters, E. J.

    1981-01-01

    Measurement technology for semiconductor materials, process control, and devices, is discussed. Silicon and silicon based devices are emphasized. Highlighted activities include semiinsulating GaAs characterization, an automatic scanning spectroscopic ellipsometer, linewidth measurement and coherence, bandgap narrowing effects in silicon, the evaluation of electrical linewidth uniformity, and arsenicomplanted profiles in silicon.

  2. Atomistic Models of Amorphous Semiconductors

    NARCIS (Netherlands)

    Jarolimek, K.

    2011-01-01

    Crystalline silicon is probably the best studied material, widely used by the semiconductor industry. The subject of this thesis is an intriguing form of this element namely amorphous silicon. It can contain a varying amount of hydrogen and is denoted as a-Si:H. It completely lacks the neat long

  3. A variable frequency semiconductor laser

    Energy Technology Data Exchange (ETDEWEB)

    Tosikhiro, F.; Khiromoto, S.

    1984-03-27

    A variable frequency, power stabilized semiconductor laser is patented. This laser includes, in addition to an active layer, a photoconducting channel layer and a layer made from a material manifesting a Pockels effect. A voltage is injected between these two layers to vary the emission frequency. The laser pumping voltage is stabilized.

  4. Point Defects in Two-Dimensional Layered Semiconductors: Physics and Its Applications

    Science.gov (United States)

    Suh, Joonki

    thermoelectric materials are thoroughly investigated. Point defects can potentially beat the undesired coupling, often term "thermoelectric Bermuda triangle", among electrical conductivity, thermal conductivity and thermopower. The maximum thermoelectric performance is demonstrated with an intermediate density of defects when they beneficially and multi-functionally act as electron donors, as well as strongly energy-dependent electron and phonon scatterers. Therefore, this is a good example of how fundamental defect physics can be applied for practical devices toward renewable energy technology. Another interesting field of layered nanomaterials is on transition-metal dichalcogenides (TMDs), sensational candidates for 2D semiconductor physics and applications. At the reduced dimensionality of 2D where a far stronger correlation between point defects and charge carriers is expected, it is studied how chalcogen vacancies alter optical properties of monolayer TMDs. A new, sub-bandgap broad emission lines as well as increase in the overall photoluminescence intensity at low temperatures are reported as a result of high quantum efficiency of excitons, i.e., bound electron-hole pairs, localized at defect sites. On electrical transport, both n- and p-type materials are needed to form junctions and support bipolar carrier conduction while typically only one type of doping is stable for a particular TMD. For example, MoS2 is natively n-type, thus the lack of p-type doping hampers the development of charge-splitting p-n junctions of MoS2. To address this issue, we demonstrate stable p-type conduction in MoS2 by substitutional Nb doping up to the degenerate level. Proof-of-concept, van der Waals p-n homo-junctions based on vertically stacked MoS2 layers are also fabricated which enable gate-tuneable current rectification. Various electronic devices fabricated are stable in ambient air even without additional treatment such as capping layer protection, thanks to the substitutionality nature

  5. Sodium and potassium doped P-type ZnO films by sol-gel spin-coating technique

    Science.gov (United States)

    Au, Benedict Wen-Cheun; Chan, Kah-Yoong

    2017-07-01

    Zinc oxide (ZnO) is a promising material in a variety of applications including sensors, transistors and solar cells. Many researchers studied N-type ZnO films and reported enhanced properties. On the other hand, P-type ZnO films were rarely attempted due to the self-compensation effect. Success in achieving P-type ZnO films is important as it will pave the way for more advanced complementary devices. In this work, P-type sodium and potassium doped ZnO films were fabricated on glass substrates with doping concentration between 0 and 25 at.%. The influences of doping concentration on surface morphology, structural, optical and electrical properties were investigated using atomic force microscopy, X-ray diffraction spectroscopy, energy-dispersive X-ray spectroscopy, ultraviolet-visible (UV-Vis) spectrophotometer, photoluminescence spectroscopy and Hall-effect electrical transport measurement system. The distinctive behavior of P-type ZnO films with different doping concentrations will be discussed.

  6. Ab initio studies on n-type and p-type Li4Ti5O12

    Institute of Scientific and Technical Information of China (English)

    Zhong Zhi-Yong; Nie Zheng-Xin; Du Yan-Lan; Ouyang Chu-Ying; Shi Si-Qi; Lei Min-Sheng

    2009-01-01

    This paper studies the structure and electronic properties of Li4Ti5O12, as anode material for lithium ion batteries,from first principles calculations. The results suggest that there are two kinds of unit cell of Li4Ti5O12: n-type and p-type. The two unit cells have different structures and electronic properties: the n-type with two 16d site Li ions is metallic by electron, while the p-type with three 16d Li ions is metallic by hole. However, the Li4Ti5O12 is an insulator.It is very interesting that one n-type cell and two p-type cells constitute one Li4Ti5O12 supercell which is insulating.The results show that the intercalation potential obtained with a p-type unit cell with one additional electron is quite close to the experimental value of 1.5 V.

  7. Nonlinear Peltier effect in semiconductors

    Science.gov (United States)

    Zebarjadi, Mona; Esfarjani, Keivan; Shakouri, Ali

    2007-09-01

    Nonlinear Peltier coefficient of a doped InGaAs semiconductor is calculated numerically using the Monte Carlo technique. The Peltier coefficient is also obtained analytically for single parabolic band semiconductors assuming a shifted Fermi-Dirac electronic distribution under an applied bias. Analytical results are in agreement with numerical simulations. Key material parameters affecting the nonlinear behavior are doping concentration, effective mass, and electron-phonon coupling. Current density thresholds at which nonlinear behavior is observable are extracted from numerical data. It is shown that the nonlinear Peltier effect can be used to enhance cooling of thin film microrefrigerator devices especially at low temperatures.

  8. High brightness semiconductor lasers with reduced filamentation

    DEFF Research Database (Denmark)

    McInerney, John; O'Brien, Peter.; Skovgaard, Peter M. W.;

    1999-01-01

    High brightness semiconductor lasers have applications in spectroscopy, fiber lasers, manufacturing and materials processing, medicine and free space communication or energy transfer. The main difficulty associated with high brightness is that, because of COD, high power requires a large aperture...

  9. Subwavelength grating as both emission mirror and electrical contact for VCSELs in any material system

    Science.gov (United States)

    Czyszanowski, Tomasz; Gebski, Marcin; Dems, Maciej; Wasiak, Michał; Sarzała, Robert; Panajotov, Krassimir

    2017-01-01

    Semiconductor-metal subwavelength grating (SMSG) can serve a dual purpose in vertical-cavity surface-emitting lasers (VCSELs), as both optical coupler and current injector. SMSGs provide optical as well as lateral current confinement, eliminating the need for ring contacts and lateral build-in optical and current confinement, allowing their implementation on arbitrarily large surfaces. Using an SMSG as the top mirror enables fabrication of monolithic VCSELs from any type of semiconductor crystal. The construction of VCSELs with SMSGs requires significantly less p-type material, in comparison to conventional VCSELs. In this paper, using a three-dimensional, fully vectorial optical model, we analyse the properties of the stand-alone SMSG in a number of semiconductor materials for a broad range of wavelengths. Integrating the optical model with thermal and electrical numerical models, we then simulate the threshold operation of an exemplary SMSG VCSEL. PMID:28079149

  10. Subwavelength grating as both emission mirror and electrical contact for VCSELs in any material system

    Science.gov (United States)

    Czyszanowski, Tomasz; Gebski, Marcin; Dems, Maciej; Wasiak, Michał; Sarzała, Robert; Panajotov, Krassimir

    2017-01-01

    Semiconductor-metal subwavelength grating (SMSG) can serve a dual purpose in vertical-cavity surface-emitting lasers (VCSELs), as both optical coupler and current injector. SMSGs provide optical as well as lateral current confinement, eliminating the need for ring contacts and lateral build-in optical and current confinement, allowing their implementation on arbitrarily large surfaces. Using an SMSG as the top mirror enables fabrication of monolithic VCSELs from any type of semiconductor crystal. The construction of VCSELs with SMSGs requires significantly less p-type material, in comparison to conventional VCSELs. In this paper, using a three-dimensional, fully vectorial optical model, we analyse the properties of the stand-alone SMSG in a number of semiconductor materials for a broad range of wavelengths. Integrating the optical model with thermal and electrical numerical models, we then simulate the threshold operation of an exemplary SMSG VCSEL.

  11. Diffusion in semiconductors, other than silicon compilation

    CERN Document Server

    Fisher, David J

    2011-01-01

    Review from Book News Inc.: Summary reports of 337 experiments provide information on the diffusion of matter and heat in 31 materials used in semiconductors. Most of the compounds are based on cadmium, gallium, indium, lead, and zinc. Mercury telluride is included however, as is silicon carbide for some reason. Each article is thoroughly referenced to the authors and publication number, date, and page. The arrangement is alphabetical by semiconductor material. Indexes cover authors, hosts, and diffusants.

  12. Organic Semiconductors and its Applications

    Science.gov (United States)

    Kamalasanan, M. N.

    2011-10-01

    Organic semiconductors in the form of evaporated or spin coated thin films have many optoelectronic applications in the present electronic industry. They are frequently used in many type of displays, photo detectors, photoconductors for photocopiers and photovoltaic cells. But many p-conjugated molecules and polymer based devices do not provide satisfactory device performance and operational stability. Most of these problems are related to the interfaces they make with other organic materials and electrodes and the low conductivity of the organic layers. The study of organic-metal and organic—organic interfaces as well as electrical doping of organic semiconductors are very important areas of research at present. In this talk, I will be discussing some of the recent advances in this field as well as some of our own results in the area of interface modification and electrical doping of organic semiconductors.

  13. Chemical fabrication of p-type Cu{sub 2}O transparent thin film using molecular precursor method

    Energy Technology Data Exchange (ETDEWEB)

    Nagai, Hiroki [Research Institute of Science and Technology, Kogakuin University, 2665-1 Nakano, Hachioji, Tokyo 192-0015 (Japan); Suzuki, Tatsuya [Department of Applied Chemistry and Chemical Engineering, Graduate School of Kogakuin University, 2665-1 Nakano, Hachioji, Tokyo 192-0015 (Japan); Hara, Hiroki; Mochizuki, Chihiro; Takano, Ichiro; Honda, Tohru [Research Institute of Science and Technology, Kogakuin University, 2665-1 Nakano, Hachioji, Tokyo 192-0015 (Japan); Sato, Mitsunobu, E-mail: lccsato@cc.kogakuin.ac.jp [Research Institute of Science and Technology, Kogakuin University, 2665-1 Nakano, Hachioji, Tokyo 192-0015 (Japan)

    2012-11-15

    A transparent p-type Cu{sub 2}O thin film of 50 nm thickness was successfully fabricated by means of a solution-based process involving the thermal reaction of molecular precursor films spin-coated on a Na-free glass substrate. The precursor solution was prepared by the reaction of an isolated Cu{sup 2+} complex of ethylenediamine-N, N, N Prime , N Prime -tetraacetic acid with dibutylamine in ethanol. The Cu{sub 2}O thin films resulting from heat treatment of the precursor film at 450 Degree-Sign C for 10 min in Ar gas at a flow rate of 1.0 L min{sup -1} were characterized by X-ray diffraction which indicated a precise cubic lattice cell parameter of a = 0.4265(2) nm, with a crystallite size of 8(2) nm. X-ray photoelectron spectroscopy peaks, attributable to the O 1s and Cu 2p{sub 3/2} level of the Cu{sub 2}O film were found at 532.6 eV and 932.4 eV, respectively. An average grain size of the deposited Cu{sub 2}O particles of ca. 200 nm was observed via field-emission scanning electron microscopy. The optical band edge evaluated from the absorption spectrum of the Cu{sub 2}O transparent thin film was 2.3 eV, assuming a direct-transition semiconductor. Hall Effect measurements of the thin film indicated that the single-phase Cu{sub 2}O thin film is a typical p-type semiconductor, with a hole concentration of 1.7 Multiplication-Sign 10{sup 16} cm{sup -3} and hole mobility of 4.8 cm{sup 2} V{sup -1} s{sup -1} at ambient temperature. The activation energy from the valence band to the acceptor level determined from an Arrhenius plot was 0.34 eV. The adhesion strength of the thin film on the Na-free glass substrate was also determined as a critical load (Lc1) of 2.0 N by means of a scratch test. The method described is the first example of fabrication and characterization of a p-type Cu{sub 2}O transparent thin film by a wet process. -- Graphical abstract: The p-type Cu{sub 2}O transparent thin film was facilely fabricated on a Na-free grass substrate by a solution based

  14. Semiconductor nanowire lasers

    Science.gov (United States)

    Eaton, Samuel W.; Fu, Anthony; Wong, Andrew B.; Ning, Cun-Zheng; Yang, Peidong

    2016-06-01

    The discovery and continued development of the laser has revolutionized both science and industry. The advent of miniaturized, semiconductor lasers has made this technology an integral part of everyday life. Exciting research continues with a new focus on nanowire lasers because of their great potential in the field of optoelectronics. In this Review, we explore the latest advancements in the development of nanowire lasers and offer our perspective on future improvements and trends. We discuss fundamental material considerations and the latest, most effective materials for nanowire lasers. A discussion of novel cavity designs and amplification methods is followed by some of the latest work on surface plasmon polariton nanowire lasers. Finally, exciting new reports of electrically pumped nanowire lasers with the potential for integrated optoelectronic applications are described.

  15. Fundamentals of semiconductor devices

    CERN Document Server

    Lindmayer, Joseph

    1965-01-01

    Semiconductor properties ; semiconductor junctions or diodes ; transistor fundamentals ; inhomogeneous impurity distributions, drift or graded-base transistors ; high-frequency properties of transistors ; band structure of semiconductors ; high current densities and mechanisms of carrier transport ; transistor transient response and recombination processes ; surfaces, field-effect transistors, and composite junctions ; additional semiconductor characteristics ; additional semiconductor devices and microcircuits ; more metal, insulator, and semiconductor combinations for devices ; four-pole parameters and configuration rotation ; four-poles of combined networks and devices ; equivalent circuits ; the error function and its properties ; Fermi-Dirac statistics ; useful physical constants.

  16. Small molecule organic semiconductors on the move: promises for future solar energy technology.

    Science.gov (United States)

    Mishra, Amaresh; Bäuerle, Peter

    2012-02-27

    This article is written from an organic chemist's point of view and provides an up-to-date review about organic solar cells based on small molecules or oligomers as absorbers and in detail deals with devices that incorporate planar-heterojunctions (PHJ) and bulk heterojunctions (BHJ) between a donor (p-type semiconductor) and an acceptor (n-type semiconductor) material. The article pays particular attention to the design and development of molecular materials and their performance in corresponding devices. In recent years, a substantial amount of both, academic and industrial research, has been directed towards organic solar cells, in an effort to develop new materials and to improve their tunability, processability, power conversion efficiency, and stability. On the eve of commercialization of organic solar cells, this review provides an overview over efficiencies attained with small molecules/oligomers in OSCs and reflects materials and device concepts developed over the last decade. Approaches to enhancing the efficiency of organic solar cells are analyzed.

  17. Emission channeling with short-lived isotopes lattice location of impurities in semiconductors and oxides

    CERN Multimedia

    We propose to perform emission channeling lattice location experiments in a number of semiconductor and oxide systems of technological relevance: \\\\- The lattice location of the transition metal probes $^{56}$Mn ($\\textit{t}_{1/2}$=2.6 h), $^{59}$Fe (45 d), $^{61}$Co (1.6 h) and $^{65}$Ni (2.5 h) is to be investigated in materials of interest as dilute magnetic semiconductors, such as GaMnAs, GaMnN, GaFeN, AlGaN, SiC, and in a number of oxides that are candidates for “single ion ferromagnetism”, in particular SrTiO$_3$ and LiNbO$_3$.\\\\- The topic of $\\textit{p}$-type doping of nitride semiconductors shall be addressed by studying the lattice sites of the acceptor dopants Mg and Be in GaN and AlN using the short-lived probes $^{27}$Mg (9.5 min) and $^{11}$Be (13.8 s). The aim is to reach a lattice location precision around 0.05 Å in order to provide critical tests for recent theoretical models which e.g. have predicted displacements of the Mg atom from the ideal substitutional Ga and Al sites of the order...

  18. Enhancement of the thermoelectric performance of p-type layered oxide Ca3Co4O9+ through heavy doping and metallic nanoinclusions

    DEFF Research Database (Denmark)

    Van Nong, Ngo; Pryds, Nini; Linderoth, Søren

    2011-01-01

    An effective way to improve the thermoelectric performance (ZT) of layered structured oxide materials by carefully choosing heavy ion doping and introducing metallic nanoinclusions is proposed. A p-type oxide material with remarkable highly improved ZT is successfully fabricated using this approach...

  19. 不同半导体材料构成光子晶体在太赫兹波段能态密度特性%State Density Properties of Photonic Crystal Composited by Different Semiconductor Material in Terahertz Band

    Institute of Scientific and Technical Information of China (English)

    邴丕彬; 闫昕

    2012-01-01

    Based on the plane wave expansion method research Ⅳ, Ⅲ-Ⅴ and Ⅱ- Ⅵ semiconductor material composition family 2d triangle photonic crystal lattice terahertz band state density of characteristics, numerical simulation to get Ⅳ family in filling SiC rate f = 0. 8 form 0. 037 THz band gap width, Ⅱ-Ⅵ ZnO family in filling rate f = 0. 73 form 0. 0417 THz band gap width form, the filler rate case Ⅲ-Ⅴ race semiconductor material form 0.027 THz band gap width, more data Ⅱ-Ⅵ race semiconductor material form more wide band gap, the result is too Hertz photonic crystal devices to provide the theoretical basis for development.%基于平面波展开法研究Ⅳ、Ⅲ-Ⅴ和Ⅱ-Ⅵ族半导体材料构成二维三角晶格光子晶体在太赫兹波段的能态密度特性,数值模拟得到Ⅳ族SiC在填充率f=0.8时形成0.037 THz带隙宽度,Ⅱ-Ⅵ族ZnO在填充率f=0.73时形成0.0417 THz带隙宽度,不同填充率情况下Ⅲ-Ⅴ族半导体材料形成0.027 THz带隙宽度,比较数据Ⅱ-Ⅵ族半导体材料形成较宽的带隙,研究结果为太赫兹光子晶体器件的开发提供了理论依据.

  20. Raman spectra of p-type transparent semiconducting Cr{sub 2}O{sub 3}:Mg

    Energy Technology Data Exchange (ETDEWEB)

    Fleischer, Karsten, E-mail: fleisck@tcd.ie; Caffrey, David; Farrell, Leo; Norton, Emma; Mullarkey, Daragh; Arca, Elisabetta; Shvets, Igor V.

    2015-11-02

    We present an analysis of the Raman spectra of p-type transparent conducting Cr{sub 2}O{sub 3}:Mg grown by various techniques including spray pyrolysis, pulsed laser deposition, molecular beam epitaxy and reactive magnetron sputtering. The best performing films show a distinct broad range Raman signature related to defect-induced vibrational modes not seen in stoichiometric, undoped material. Our comparative study demonstrates that Raman spectroscopy can quantify unwanted dopant clustering in the material at high Mg concentrations, while also being sensitive to the Mg incorporation site. By correlating the Raman signature to the electrical properties of the films, growth processes can be optimised to give the best conducting films and the local defect structure for effective p-type doping can be studied. - Highlights: • Mg doping in Cr{sub 2}O{sub 3} can lead to dopant clustering in MgCr{sub 2}O{sub 4} phase. • Post-annealing in oxygen can dissolve these clusters improving doping. • High oxygen pressures during growth can prevent dopant clustering. • Raman spectroscopy is a powerful tool to assist growth optimization in p-type oxides.

  1. Photocatalytic semiconductors synthesis, characterization, and environmental applications

    CERN Document Server

    Hernández-Ramírez, Aracely

    2014-01-01

    This critical volume examines the different methods used for the synthesis of a great number of photocatalysts, including TiO2, ZnO and other modified semiconductors, as well as characterization techniques used for determining the optical, structural and morphological properties of the semiconducting materials. Additionally, the authors discuss photoelectrochemical methods for determining the light activity of the photocatalytic semiconductors by means of measurement of properties such as band gap energy, flat band potential and kinetics of hole and electron transfer. Photocatalytic Semiconductors: Synthesis, Characterization and Environmental Applications provide an overview of the semiconductor materials from first- to third-generation photocatalysts and their applications in wastewater treatment and water disinfection. The book further presents economic and toxicological aspects in the production and application of photocatalytic materials.

  2. Semiconductor High-Energy Radiation Scintillation Detector

    CERN Document Server

    Kastalsky, A; Spivak, B

    2006-01-01

    We propose a new scintillation-type detector in which high-energy radiation produces electron-hole pairs in a direct-gap semiconductor material that subsequently recombine producing infrared light to be registered by a photo-detector. The key issue is how to make the semiconductor essentially transparent to its own infrared light, so that photons generated deep inside the semiconductor could reach its surface without tangible attenuation. We discuss two ways to accomplish this, one based on doping the semiconductor with shallow impurities of one polarity type, preferably donors, the other by heterostructure bandgap engineering. The proposed semiconductor scintillator combines the best properties of currently existing radiation detectors and can be used for both simple radiation monitoring, like a Geiger counter, and for high-resolution spectrography of the high-energy radiation. The most important advantage of the proposed detector is its fast response time, about 1 ns, essentially limited only by the recombi...

  3. Inorganic semiconductors for flexible electronics.

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Y.; Rogers, J. A.; Center for Nanoscale Materials; Univ. of Illinois

    2007-08-03

    This article reviews several classes of inorganic semiconductor materials that can be used to form high-performance thin-film transistors (TFTs) for large area, flexible electronics. Examples ranging from thin films of various forms of silicon to nanoparticles and nanowires of compound semiconductors are presented, with an emphasis on methods of depositing and integrating thin films of these materials into devices. Performance characteristics, including both electrical and mechanical behavior, for isolated transistors as well as circuits with various levels of complexity are reviewed. Collectively, the results suggest that flexible or printable inorganic materials may be attractive for a range of applications not only in flexible but also in large-area electronics, from existing devices such as flat-panel displays to more challenging (in terms of both cost and performance requirements) systems such as large area radiofrequency communication devices, structural health monitors, and conformal X-ray imagers.

  4. Quantum processes in semiconductors

    CERN Document Server

    Ridley, B K

    2013-01-01

    Aimed at graduate students, this is a guide to quantum processes of importance in the physics and technology of semiconductors. The fifth edition includes new chapters that expand the coverage of semiconductor physics relevant to its accompanying technology.

  5. Electrical contacts for a thin-film semiconductor device

    Science.gov (United States)

    Carlson, David E.; Dickson, Charles R.; D'Aiello, Robert V.

    1989-08-08

    A method of fabricating spaced-apart back contacts on a thin film of semiconductor material by forming strips of buffer material on top of the semiconductor material in locations corresponding to the desired dividing lines between back contacts, forming a film of metal substantially covering the semiconductor material and buffer strips, and scribing portions of the metal film overlying the buffer strips with a laser without contacting the underlying semiconductor material to separate the metal layer into a plurality of back contacts. The buffer material serves to protect the underlying semiconductor material from being damaged during the laser scribing. Back contacts and multi-cell photovoltaic modules incorporating such back contacts also are disclosed.

  6. Squeezed light in semiconductors

    CERN Document Server

    Ward, M B

    2001-01-01

    Experimental evidence is presented for the generation of photon-number squeezed states of light as a result of multi-photon absorption. Photon-number squeezing as a result of non-linear absorption has long been predicted and results have been obtained utilising two very different material systems: (i) an AIGaAs waveguide in which high optical intensities can be maintained over a relatively long interaction length of 2 mm; (ii) the organic polymer p-toluene sulphonate polydiacetylene that is essentially a one-dimensional semiconductor possessing a highly nonlinear optical susceptibility. The resulting nonlinear absorption is shown to leave the transmitted light in a state that is clearly nonclassical, exhibiting photon-number fluctuations below the shot-noise limit. Tuning the laser wavelength across the half-bandgap energy has enabled a comparison between two- and three-photon processes in the semiconductor waveguide. The correlations created between different spectral components of a pulsed beam of light as ...

  7. A novel mechanism of P-type ATPase autoinhibition involving both termini of the protein

    DEFF Research Database (Denmark)

    Ekberg, Kira; Palmgren, Michael; Veierskov, Bjarke;

    2010-01-01

    The activity of many P-type ATPases is found to be regulated by interacting proteins or autoinhibitory elements located in N- or C-terminal extensions. An extended C terminus of fungal and plant P-type plasma membrane H+-ATPases has long been recognized to be part of a regulatory apparatus...

  8. Demethoxycurcumin is a potent inhibitor of P-type ATPases from diverse kingdoms of life

    DEFF Research Database (Denmark)

    Dao, Trong Tuan; Sehgal, Pankaj; Thanh Tung, Truong;

    2016-01-01

    P-type ATPases catalyze the active transport of cations and phospholipids across biological membranes. Members of this large family are involved in a range of fundamental cellular processes. To date, a substantial number of P-type ATPase inhibitors have been characterized, some of which are used ...

  9. Handbook of spintronic semiconductors

    CERN Document Server

    Chen, Weimin

    2010-01-01

    Offers a review of the field of spintronic semiconductors. This book covers a range of topics, including growth and basic physical properties of diluted magnetic semiconductors based on II-VI, III-V and IV semiconductors, developments in theory and experimental techniques and potential device applications.

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

    Science.gov (United States)

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

    2013-09-01

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

  11. Organic semiconductors as candidates for advanced optoelectronic devices:

    OpenAIRE

    Bratina, Gvido; Hudej, Robert

    2001-01-01

    Organic semiconductors are gaining an increasing attention due to their promise of novel optoelectronic devices. The main attraction of these materials stems from their potential integration with flexible materials, which would result in ultrathin flexible multicolor displays. Basic electronic properties of typical representatives of organic semiconductors are reviewed. The operation of a light-emitting device based on organic semiconductors is fundamentally different from its inorganic count...

  12. Characteristics and optimization of 4H-SiC MESFET with a novel p-type spacer layer incorporated with a field-plate structure based on improved trap models

    Energy Technology Data Exchange (ETDEWEB)

    Song Kun; Chai Changchun; Yang Yintang; Jia Hujun; Zhang Xianjun; Chen Bin, E-mail: sk88205853@sina.com [Key Laboratory of Wide Band-Gap Semiconductor Materials and Devices of the Ministry of Education, School of Microelectronics, Xidian University, Xi' an 710071 (China)

    2011-07-15

    A novel structure of 4H-SiC MESFETs is proposed that focuses on surface trap suppression. Characteristics of the device have been investigated based on physical models for material properties and improved trap models. By comparing with the performance of the well-utilized buried-gate incorporated with a field-plate (BG-FP) structure, it is shown that the proposed structure improves device properties in comprehensive aspects. A p-type spacer layer introduced in the channel layer suppresses the surface trap effect and reduces the gate-drain capacitance (C{sub gd}) under a large drain voltage. A p-type spacer layer incorporated with a field-plate improves the electric field distribution on the gate edge while the spacer layer induces less C{sub gd} than a conventional FP. For microwave applications, 4H-SiC MESFET for the proposed structure has a larger gate-lag ratio in the saturation region due to better surface trap isolation from the conductive channel. For high power applications, the proposed structure is able to endure higher operating voltage as well. The maximum saturation current density of 460 mA/mm is yielded. Also, the gate-lag ratio under a drain voltage of 20 V is close to 90%. In addition, 5% and 17.8% improvements in f{sub T} and f{sub max} are obtained compared with a BG-FP MESFET in AC simulation, respectively. Parameters and dimensions of the proposed structure are optimized to make the best of the device for microwave applications and to provide a reference for device design. (semiconductor devices)

  13. Diffusion in isotopically controlled semiconductor systems

    Science.gov (United States)

    Bracht, H.

    1999-12-01

    Isotopically controlled heterostructures of 28Si/natSi and Al71GaAs/Al69GaAs/71GaAs have been used to study the self-diffusion process in this elemental and compound semiconductor material. The directly measured Si self-diffusion coefficient is compared with the self-interstitial and vacancy contribution to self-diffusion which were deduced from metal diffusion experiments. The remarkable agreement between the Si self-diffusion coefficients and the individual contributions to self-diffusion shows that both self-interstitials and vacancies mediate Si self-diffusion. The Ga self-diffusion in undoped AlGaAs was found to decrease with increasing Al concentration. The activation enthalpy of Ga and Al diffusion in GaAs and of Ga diffusion in AlGaAs all lie in the range of (3.6±0.1) eV, but with different pre-exponential factors. The doping dependence of Ga self-diffusion reveals a retardation (enhancement) of Ga diffusion under p-type (n-type) doping compared to intrinsic conditions. All experimental results on the group-III atom diffusion are accurately described if vacancies on the group-III sublattice are assumed to mediate the Ga self- and Al-Ga interdiffusion in undoped AlGaAs and the Ga self-diffusion in Be- and Si-doped GaAs with an active dopant concentration of 3×1018 cm-3. The doping dependence of Ga self-diffusion in GaAs provides strong evidence that neutral, singly and doubly charged Ga vacancies govern the self-diffusion process.

  14. Unitary lens semiconductor device

    Science.gov (United States)

    Lear, Kevin L.

    1997-01-01

    A unitary lens semiconductor device and method. The unitary lens semiconductor device is provided with at least one semiconductor layer having a composition varying in the growth direction for unitarily forming one or more lenses in the semiconductor layer. Unitary lens semiconductor devices may be formed as light-processing devices such as microlenses, and as light-active devices such as light-emitting diodes, photodetectors, resonant-cavity light-emitting diodes, vertical-cavity surface-emitting lasers, and resonant cavity photodetectors.

  15. Studies on electrochemically constructed n- and p-type photoelectrodes for use in solar energy conversion

    Science.gov (United States)

    Kang, Donghyeon

    Among several pathways to harvest solar energy, solar water splitting is one of the most efficient methods to convert solar light to hydrogen, which is a clean and easy to store chemical that has the potential to be used as a fuel source. Solar water splitting can be achieved primarily by photoelectrochemical cells (PECs), which utilize semiconductors as photoelectrodes for the water splitting reaction. Photoelectrodes play the crucial role of generating hydrogen but, to date, very few photoelectrodes have been developed that can produce hydrogen in a stable and efficient manner. Thus, development and modification of efficient, stable photoelectrodes are highly desirable to improve performance of solar water splitting PECs. This dissertation demonstrates the development of semiconductors as photoelectrodes and their modifications to advance solar energy conversion performance by newly established electrochemical synthetic routes. To improve the photoelectrochemical performance of photoelectrodes, various strategies were introduced, such as, morphology control, extrinsic doping, and the integration of catalysts. After successfully demonstrating the electrochemical synthesis of photoelectrodes, photoelectrochemical and electrochemical properties of electrodeposited photoelectrodes in PECs are discussed. The chapters can be categorized into three major themes. The first theme is the preparation of Bi-based photoanodes for the water oxidation reaction. Chapter 2 presents a study of Mo-doping into the BiVO4 photoanode to enhance charge separation properties. After Mo-doping was achieved successfully, a FeOOH oxygen evoltuion catalyst was integrated into the Mo-doped BiVO 4 photoanode to increase the water oxidation performance. Chapter 3 introduces another electrochemical synthesis method to control the morphology of Bi-based oxide photoanode materials. The second theme of this dissertation is the preparation of photocathode materials for the water reduction reaction

  16. A semiconductor based electrode

    Energy Technology Data Exchange (ETDEWEB)

    Khamatani, A.; Kobayasi, K.

    1983-03-30

    The semiconductor electrode is submerged into an electrolyte which is held in the illuminated chamber. The other electrode is placed in a dark chamber connected with the channel to be illuminated, which has a partition in the form of a membrane. An electric current flows in the external circuit of the element with illumination of the first electrode. The illuminated electrode is covered with a thin film of a substance which is stable with the action of the electrolyte. The film is made of Si02, A1203, GaN or A1N. The protective coating makes it possible to use materials less stable than Ti02 in a rutile modification, but which have higher characteristics than the GaP, GaAs, CdS and InP, for making the electrode.

  17. Semiconductor Nanostructures Quantum States and Electronic Transport

    CERN Document Server

    Ihn, Thomas

    2009-01-01

    This textbook describes the physics of semiconductor nanostructures with emphasis on their electronic transport properties. At its heart are five fundamental transport phenomena: quantized conductance, tunnelling transport, the Aharonov-Bohm effect, the quantum Hall effect, and the Coulomb blockade effect. The book starts out with the basics of solid state and semiconductor physics, such as crystal structure, band structure, and effective mass approximation, including spin-orbit interaction effects important for research in semiconductor spintronics. It contains material aspects such as band e

  18. Comparative studies on p-type CuI grown on glass and copper substrate by SILAR method

    Energy Technology Data Exchange (ETDEWEB)

    Dhere, Sunetra L.; Latthe, Sanjay S. [Air Glass Laboratory, Department of Physics, Shivaji University, Kolhapur 416 004, Maharashtra (India); Kappenstein, Charles [University of Poitiers, Laboratory of Catalysis in Organic Chemistry, LA CCO, UMR CNRS 6503, Poitiers-86000 (France); Mukherjee, S.K. [Fuel Chemistry Division, Bhabha Atomic Research Centre, Trombay, Mumbai - 400085, Maharashtra India (India); Rao, A. Venkateswara, E-mail: avrao2012@gmail.com [Air Glass Laboratory, Department of Physics, Shivaji University, Kolhapur 416 004, Maharashtra (India)

    2010-04-01

    Depending upon the method of synthesis and the nature of substrate surface, there is variation in the physico-chemical properties of the material. Cuprous iodide films are deposited at room temperature on the glass and copper substrates by a simple SILAR method and the obtained results are compared. The p-type material with optical band gap 2.88 eV is found to be possessing face-centered cubic crystal structure with lattice parameter 6.134 A. We observed irregular particles for the CuI film on the glass substrate while patterned arrays of micro-rods with cabbage like tips on copper substrate, for the same preparative conditions. Also, the material deposited on copper is showing superhydrophobic nature (contact angle {approx}156{sup o}) while that on glass it is hydrophilic (contact angle {approx}88{sup o}). We have characterized the thin films by X-ray diffraction, scanning electron microscopy, surface roughness and contact angle measurement, thermoelectric power measurement and optical studies. This hydrophobic, p-type material with wide band gap will be helpful in the development of optoelectronic devices.

  19. Comparative studies on p-type CuI grown on glass and copper substrate by SILAR method

    Science.gov (United States)

    Dhere, Sunetra L.; Latthe, Sanjay S.; Kappenstein, Charles; Mukherjee, S. K.; Rao, A. Venkateswara

    2010-04-01

    Depending upon the method of synthesis and the nature of substrate surface, there is variation in the physico-chemical properties of the material. Cuprous iodide films are deposited at room temperature on the glass and copper substrates by a simple SILAR method and the obtained results are compared. The p-type material with optical band gap 2.88 eV is found to be possessing face-centered cubic crystal structure with lattice parameter 6.134 Å. We observed irregular particles for the CuI film on the glass substrate while patterned arrays of micro-rods with cabbage like tips on copper substrate, for the same preparative conditions. Also, the material deposited on copper is showing superhydrophobic nature (contact angle ˜156°) while that on glass it is hydrophilic (contact angle ˜88°). We have characterized the thin films by X-ray diffraction, scanning electron microscopy, surface roughness and contact angle measurement, thermoelectric power measurement and optical studies. This hydrophobic, p-type material with wide band gap will be helpful in the development of optoelectronic devices.

  20. SEMICONDUCTOR MATERIALS Theoretical investigation of efficiency of a p-a-SiC:H/i-a-Si:H/n-μc-Si solar cell

    Science.gov (United States)

    Qingwen, Deng; Xiaoliang, Wang; Hongling, Xiao; Zeyu, Ma; Xiaobin, Zhang; Qifeng, Hou; Jinmin, Li; Zhanguo, Wang

    2010-10-01

    A solar cell with a novel structure is investigated by means of the analysis of microelectronic and photonic structure (AMPS). The power conversion efficiency is investigated with the variations in interface recombination velocity, thicknesses of p-type layer, intrinsic layer, n-type layer, and doping density. Results show that it is available and preferable in theory to employ a-SiC:H as a window layer in p-a-SiC:H/i-a-Si:H/n-μc-Si solar cells, and provide a new approach to improving the power conversion efficiency of amorphous silicon solar cells.

  1. Using the hydrothermal method to grow p-type ZnO nanowires on Al-doped ZnO thin film to fabricate a homojunction diode.

    Science.gov (United States)

    Tseng, Yung-Kuan; Hung, Meng-Chun; Su, Shun-Lung; Li, Sheng-Kai

    2014-10-01

    In this study, the hydrothermal method is used to grow phosphorus-doped ZnO nanowires on Si/SiO2 substrates deposited with Al-doped ZnO thin film. This structure forms a homogeneous p-n junction. In this study, we are the pioneers to use ammonium hypophosphite (NH4H2PO2) as a source of phosphorus to prepare the precursor solution. Ammonium hypophosphite of different concentration levels is used to observe its effects on the growth of nanowires. The results show that the precursor solution prepared from ammonium hypophosphite can produce good crystalline ZnO nanowires while there is no linear relationship between the amounts and concentration levels of phosphorus doped into the nanowires. Whether the phosphorus-doped ZnO nanowires have the characteristics of a p-type semiconductor is indirectly verified by measuring whether the p-n junction made up of Al-doped ZnO thin film and phosphorus-doped ZnO nanowires shows rectifying behavior. I-V measurements are made on the specimens. The results show good rectifying behavior, proving that the phosphorus-doped ZnO nanowires and Al-doped AZO films have p-type and n-type semiconductor properties, constituting a good p-n junction. This result also proves that ammonium hypophosphite is a better source of phosphorus in the hydrothermal method to synthesize phosphorus-doped ZnO nanowires.

  2. Controlled growth of semiconductor crystals

    Science.gov (United States)

    Bourret-Courchesne, Edith D.

    1992-01-01

    A method for growth of III-V, II-VI and related semiconductor single crystals that suppresses random nucleation and sticking of the semiconductor melt at the crucible walls. Small pieces of an oxide of boron B.sub.x O.sub.y are dispersed throughout the comminuted solid semiconductor charge in the crucible, with the oxide of boron preferably having water content of at least 600 ppm. The crucible temperature is first raised to a temperature greater than the melt temperature T.sub.m1 of the oxide of boron (T.sub.m1 =723.degree. K. for boron oxide B.sub.2 O.sub.3), and the oxide of boron is allowed to melt and form a reasonably uniform liquid layer between the crucible walls and bottom surfaces and the still-solid semiconductor charge. The temperature is then raised to approximately the melt temperature T.sub.m2 of the semiconductor charge material, and crystal growth proceeds by a liquid encapsulated, vertical gradient freeze process. About half of the crystals grown have a dislocation density of less than 1000/cm.sup.2. If the oxide of boron has water content less than 600 ppm, the crucible material should include boron nitride, a layer of the inner surface of the crucible should be oxidized before the oxide of boron in the crucible charge is melted, and the sum of thicknesses of the solid boron oxide layer and liquid boron oxide layer should be at least 50 .mu.m.

  3. Thermal Stability of P-Type BiSbTe Alloys Prepared by Melt Spinning and Rapid Sintering

    Directory of Open Access Journals (Sweden)

    Yun Zheng

    2017-06-01

    Full Text Available P-type BiSbTe alloys have been widely implemented in waste heat recovery from low-grade heat sources below 600 K, which may involve assorted environments and conditions, such as long-term service, high-temperature exposure (generally 473–573 K and mechanical forces. It is important to evaluate the service performance of these materials in order to prevent possible failures in advance and extend the life cycle. In this study, p-type Bi0.5Sb1.5Te3 commercial zone-melting (ZM ingots were processed by melt spinning and subsequent plasma-activated sintering (MS-PAS, and were then subjected to vacuum-annealing at 473 and 573 K, respectively, for one week. The results show that MS-PAS samples exhibit excellent thermal stability when annealed at 473 K. However, thermal annealing at 573 K for MS-PAS specimens leads to the distinct sublimation of the element Te, which degrades the hole concentration remarkably and results in inferior thermoelectric performance. Furthermore, MS-PAS samples annealed at 473 K demonstrate a slight enhancement in flexural and compressive strengths, probably due to the reduction of residual stress induced during the sintering process. The current work guides the reliable application of p-type Bi0.5Sb1.5Te3 compounds prepared by the MS-PAS technique.

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

    Science.gov (United States)

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

    2016-06-28

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

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

    Science.gov (United States)

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

    2016-06-01

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

  6. Thermal Stability of P-Type BiSbTe Alloys Prepared by Melt Spinning and Rapid Sintering.

    Science.gov (United States)

    Zheng, Yun; Tan, Gangjian; Luo, Yubo; Su, Xianli; Yan, Yonggao; Tang, Xinfeng

    2017-06-06

    P-type BiSbTe alloys have been widely implemented in waste heat recovery from low-grade heat sources below 600 K, which may involve assorted environments and conditions, such as long-term service, high-temperature exposure (generally 473-573 K) and mechanical forces. It is important to evaluate the service performance of these materials in order to prevent possible failures in advance and extend the life cycle. In this study, p-type Bi0.5Sb1.5Te₃ commercial zone-melting (ZM) ingots were processed by melt spinning and subsequent plasma-activated sintering (MS-PAS), and were then subjected to vacuum-annealing at 473 and 573 K, respectively, for one week. The results show that MS-PAS samples exhibit excellent thermal stability when annealed at 473 K. However, thermal annealing at 573 K for MS-PAS specimens leads to the distinct sublimation of the element Te, which degrades the hole concentration remarkably and results in inferior thermoelectric performance. Furthermore, MS-PAS samples annealed at 473 K demonstrate a slight enhancement in flexural and compressive strengths, probably due to the reduction of residual stress induced during the sintering process. The current work guides the reliable application of p-type Bi0.5Sb1.5Te₃ compounds prepared by the MS-PAS technique.

  7. Crystal growth and characterization of the narrow-band-gap semiconductors OsPn₂ (Pn = P, As, Sb).

    Science.gov (United States)

    Bugaris, Daniel E; Malliakas, Christos D; Shoemaker, Daniel P; Do, Dat T; Chung, Duck Young; Mahanti, Subhendra D; Kanatzidis, Mercouri G

    2014-09-15

    Using metal fluxes, crystals of the binary osmium dipnictides OsPn2 (Pn = P, As, Sb) have been grown for the first time. Single-crystal X-ray diffraction confirms that these compounds crystallize in the marcasite structure type with orthorhombic space group Pnnm. The structure is a three-dimensional framework of corner- and edge-sharing OsPn6 octahedra, as well as [Pn2(4-)] anions. Raman spectroscopy shows the presence of P-P single bonds, consistent with the presence of [Pn2(-4)] anions and formally Os(4+) cations. Optical-band-gap and high-temperature electrical resistivity measurements indicate that these materials are narrow-band-gap semiconductors. The experimentally determined Seebeck coefficients reveal that nominally undoped OsP2 and OsSb2 are n-type semiconductors, whereas OsAs2 is p-type. Electronic band structure using density functional theory calculations shows that these compounds are indirect narrow-band-gap semiconductors. The bonding p orbitals associated with the Pn2 dimer are below the Fermi energy, and the corresponding antibonding states are above, consistent with a Pn-Pn single bond. Thermopower calculations using Boltzmann transport theory and constant relaxation time approximation show that these materials are potentially good thermoelectrics, in agreement with experiment.

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

    Science.gov (United States)

    Lin, Tengda; Li, Xiuling; Jang, Jin

    2016-06-01

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

  9. Robust p-type doping of copper oxide using nitrogen implantation

    Science.gov (United States)

    Jorge, Marina; Polyakov, Stanislav M.; Cooil, Simon; Schenk, Alex K.; Edmonds, Mark; Thomsen, Lars; Mazzola, Federico; Wells, Justin W.

    2017-07-01

    We demonstrate robust p-type doping of Cu2O using low/medium energy ion implantation. Samples are made by controlled oxidation of annealed Cu metal foils, which results in Cu2O with levels of doping close to intrinsic. Samples are then implanted with nitrogen ions using a kinetic energy in the few keV range. Using this method, we are able to produce very high levels of doping, as evidenced by a 350 meV shift in the Fermi level towards the VB maximum. The robustness of the nitrogen implanted samples are tested by exposing them to atmospheric contaminants, and elevated temperatures. The samples are found to survive an increase in temperature of many hundreds of degrees. The robustness of the samples, combined with the fact that the materials used are safe, abundant and non-toxic and that the methods used for the growth of Cu2O and N+ implantation are simple and cheap to implement industrially, underlines the potential of Cu2O:N for affordable intermediate band photovoltaics.

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

    Science.gov (United States)

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

    2017-01-01

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

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

    Science.gov (United States)

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

    2011-02-01

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

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

    Science.gov (United States)

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

    2017-03-01

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

  13. Silver-Assisted Chemical Etching of Semiconductor Materials%银辅助化学刻蚀半导体材料

    Institute of Scientific and Technical Information of China (English)

    耿学文; 贺春林; 徐仕翀; 李俊刚; 朱丽娟; 赵连城

    2012-01-01

    微电子器件的发展趋势是小型化和多功能化,这就对半导体材料的加工技术提出了更高的要求。与传统的加工技术相比,近年发展起来的贵金属粒子辅助化学刻蚀半导体材料制备微结构技术因操作简单、不需要精密设备、反应迅速和可批量生产等优点引起了国内外学者的广泛关注。本文以Si为主,详细介绍了Ag辅助化学刻蚀半导体材料的机理、反应现象及影响因素,总结了各种微结构的制备技术及其应用。此外,对Ge,Si1-xGex和GaAs等其他半导体材料的贵金属粒子辅助化学刻蚀技术也进行了综述。同时分析了贵金属粒子辅助化学刻蚀半导体目前存在的问题,并对未来的研究方向进行了展望。%Semiconductors with various structural morphologies are widely used in areas of electronics, optoelectronics, photovohaics, sensors and thermoelectrics. The fabrication of solid-state micro/nanostructures has been motivated by the miniaturization and multi-functionality of microelectronic devices. Although some traditional methods can be used for texturization treatment of semiconductors, their applications are limited to some extent owing to their intrinsic disadvantages. Recently, the technologies of noble metal-assisted chemical etching (MacEtch) of semiconductors to produce micro/nanostructures have been paid much attention due to their relatively simple processes, fast reacting rate, low cost, and applicability for mass production etc. In this review, firstly, the MacEtch mechanisms, reaction phenomena and effect factors (including the depositing methods, distribution, sizes, shape of Ag particles, and the composition of etchants) of Ag-assisted chemical etching of Si semiconductor are discussed in detail. And then the fabrication technologies of various microstructures such as porous Si, Si nanostructures, silicon nanowire arrays, and quasi-ordered micro/nanostructures are introduced to

  14. Photovoltaic healing of non-uniformities in semiconductor devices

    Energy Technology Data Exchange (ETDEWEB)

    Karpov, Victor G.; Roussillon, Yann; Shvydka, Diana; Compaan, Alvin D.; Giolando, Dean M.

    2006-08-29

    A method of making a photovoltaic device using light energy and a solution to normalize electric potential variations in the device. A semiconductor layer having nonuniformities comprising areas of aberrant electric potential deviating from the electric potential of the top surface of the semiconductor is deposited onto a substrate layer. A solution containing an electrolyte, at least one bonding material, and positive and negative ions is applied over the top surface of the semiconductor. Light energy is applied to generate photovoltage in the semiconductor, causing a redistribution of the ions and the bonding material to the areas of aberrant electric potential. The bonding material selectively bonds to the nonuniformities in a manner such that the electric potential of the nonuniformities is normalized relative to the electric potential of the top surface of the semiconductor layer. A conductive electrode layer is then deposited over the top surface of the semiconductor layer.

  15. Review of wide band-gap semiconductors technology

    Directory of Open Access Journals (Sweden)

    Jin Haiwei

    2016-01-01

    Full Text Available Silicon carbide (SiC and gallium nitride (GaN are typical representative of the wide band-gap semiconductor material, which is also known as third-generation semiconductor materials. Compared with the conventional semiconductor silicon (Si or gallium arsenide (GaAs, wide band-gap semiconductor has the wide band gap, high saturated drift velocity, high critical breakdown field and other advantages; it is a highly desirable semiconductor material applied under the case of high-power, high-temperature, high-frequency, anti-radiation environment. These advantages of wide band-gap devices make them a hot spot of semiconductor technology research in various countries. This article describes the research agenda of United States and European in this area, focusing on the recent developments of the wide band-gap technology in the US and Europe, summed up the facing challenge of the wide band-gap technology.

  16. Diffusion in Intrinsic and Highly Doped III-V Semiconductors

    CERN Multimedia

    Stolwijk, N

    2002-01-01

    %title\\\\ \\\\Diffusion plays a key role in the fabrication of semiconductor devices. The diffusion of atoms in crystals is mediated by intrinsic point defects. Investigations of the diffusion behaviour of self- and solute atoms on the Ga sublattice of gallium arsenide led to the conclusion that in intrinsic and n-type material charged Ga vacancies are involved in diffusion processes whereas in p-type material diffusion if governed by charged Ga self-interstitials. Concerning the As sublattice of gallium arsenide there is a severe lack of reliable diffusion data. The few available literature data on intrinsic GaAs are not mutually consistent. A systematic study of the doping dependence of diffusion is completely missing. The most basic diffusion process - self-diffusion of As and its temperature and doping dependence - is practically not known. For GaP a similar statement holds.\\\\ \\\\The aim of the present project is to perform a systematic diffusion study of As diffusion in intrinsic and doped GaAs and in GaP. P...

  17. Strain sensitivity of band gaps of Sn-containing semiconductors

    DEFF Research Database (Denmark)

    Li, Hong; Castelli, Ivano Eligio; Thygesen, Kristian Sommer

    2015-01-01

    Tuning of band gaps of semiconductors is a way to optimize materials for applications within photovoltaics or as photocatalysts. One way to achieve this is through applying strain to the materials. We investigate the effect of strain on a range of Sn-containing semiconductors using density...

  18. Workshop report and presentations from the Semiconductor Research Corporation-DOE Semiconductor Task Force Workshop

    Science.gov (United States)

    The Semiconductor Research Corporation-DOE Semiconductor Task Force Workshop was held in Oak ridge, Tennessee, on November 2-3, 1987. It was to provide a forum for representatives of the national laboratories, DOE, and the semiconductor industry in which to discuss capabilities of the national laboratories which could contribute to the future competitiveness of the US semiconductor industry, to identify specific large and small projects at the national laboratories which would be of direct benefit to the semiconductor industry, and to find ways of implementing these projects. Numerous small projects were identified which would utilize unique capabilities of the national laboratories in advanced ion implantation, plasma processing (including electron cyclotron resonance plasmas), ion and cluster beam deposition, materials characterization, electronic packaging, and laser processing and deposition. Five large-scale candidate projects were identified in synchrotron x-ray lithography, silicon process integration, advanced materials processing science, process analysis and diagnostics, and ultra clean room engineering. The major obstacle to implementing these projects if the lack of appropriate funds to initiate and stimulate interactions between the national laboratories and the semiconductor industry. SEMATECH and the federal government are potential sources of seed funds for these projects. The Semiconductor Research Corporation is ideally suited to interface the semiconductor industry and the national laboratories for many of these interactions.

  19. Recent progress in the development of semiconductor-based photocatalyst materials for applications in photocatalytic water splitting and degradation of pollutants

    CSIR Research Space (South Africa)

    Opoku, F

    2017-07-01

    Full Text Available . The VB and CB edges of commonly used semicon- ductors[36] with reference to EH /H2 + and EO /H O2 2 potentials are given in Figure 1. If ECB is positioned more negative than the EH /H2 + potential and the EVB is also aligned more positive than the EO.... Sustainable Syst. 2017, 1700006 Table 1. The band gap, CB (ECB) and VB (EVB) edge positions of commonly used semiconductors at pH zero versus normal hydrogen electrode (NHE) (Adapted with permission[36]). (ECB – conduction band edge, EVB – valence band edge...

  20. Electron beam pumped semiconductor laser

    Science.gov (United States)

    Hug, William F. (Inventor); Reid, Ray D. (Inventor)

    2009-01-01

    Electron-beam-pumped semiconductor ultra-violet optical sources (ESUVOSs) are disclosed that use ballistic electron pumped wide bandgap semiconductor materials. The sources may produce incoherent radiation and take the form of electron-beam-pumped light emitting triodes (ELETs). The sources may produce coherent radiation and take the form of electron-beam-pumped laser triodes (ELTs). The ELTs may take the form of electron-beam-pumped vertical cavity surface emitting lasers (EVCSEL) or edge emitting electron-beam-pumped lasers (EEELs). The semiconductor medium may take the form of an aluminum gallium nitride alloy that has a mole fraction of aluminum selected to give a desired emission wavelength, diamond, or diamond-like carbon (DLC). The sources may be produced from discrete components that are assembled after their individual formation or they may be produced using batch MEMS-type or semiconductor-type processing techniques to build them up in a whole or partial monolithic manner, or combination thereof.