WorldWideScience

Sample records for semiconductor heteroepitaxial islands

  1. Kinetic Monte Carlo simulation of intermixing during semiconductor heteroepitaxy

    Science.gov (United States)

    Rouhani, M. Djafari; Kassem, H.; Dalla Torre, J.; Landa, G.; Estève, D.

    2002-03-01

    We have used the kinetic Monte Carlo technique to investigate the intermixing mechanisms during the heteroepitaxial growth of semiconductors. We have shown that the temperature increases the intermixing between the substrate and deposited film, while an increasing growth rate inhibits this intermixing. We have also observed that intermixing is reduced when the energetics becomes unfavorable, i.e. with high lattice mismatches or hard-deposited materials.

  2. 3D heteroepitaxy of mismatched semiconductors on silicon

    International Nuclear Information System (INIS)

    Falub, Claudiu V.; Kreiliger, Thomas; Isa, Fabio; Taboada, Alfonso G.; Meduňa, Mojmír; Pezzoli, Fabio; Bergamaschini, Roberto; Marzegalli, Anna; Müller, Elisabeth; Chrastina, Daniel; Isella, Giovanni; Neels, Antonia; Niedermann, Philippe; Dommann, Alex; Miglio, Leo; Känel, Hans von

    2014-01-01

    We present a method for monolithically integrating mismatched semiconductor materials with Si, coined three-dimensional (3D) heteroepitaxy. The method comprises the replacement of conventional, continuous epilayers by dense arrays of strain- and defect-free, micron-sized crystals. The crystals are formed by a combination of deep-patterning of the Si substrates and self-limited lateral expansion during the epitaxial growth. Consequently, the longstanding issues of crack formation and wafer bowing can be avoided. Moreover, threading dislocations can be eliminated by appropriately choosing pattern sizes, layer thicknesses and surface morphology, the latter being dependent on the growth temperature. We show this approach to be valid for various material combinations, pattern geometries and substrate orientations. We demonstrate that Ge crystals evolve into perfect structures away from the heavily dislocated interface with Si, by using a synchrotron X-ray beam focused to a spot a few hundred nanometers in size and by recording 3D reciprocal space maps along their height. Room temperature photoluminescence (PL) experiments reveal that the interband integrated PL intensity of the Ge crystals is enhanced by almost three orders of magnitude with respect to that of Ge epilayers directly grown on flat Si substrates. Electrical measurements performed on single heterojunction diodes formed between 3D Ge crystals and the Si substrate exhibit rectifying behavior with dark currents of the order of 1 mA/cm 2 . For GaAs the thermal strain relaxation as a function of pattern size is similar to that found for group IV materials. Significant differences exist, however, in the evolution of crystal morphology with pattern size, which more and more tends to a pyramidal shape defined by stable {111} facets with decreasing width of the Si pillars. - Highlights: • Νew method for integrating mismatched semiconductors • Arrays of three-dimensional epitaxial Ge and GaAs crystals on Si

  3. Understanding the effects of strain on morphological instabilities of a nanoscale island during heteroepitaxial growth

    Energy Technology Data Exchange (ETDEWEB)

    Feng, Lu; Wang, Jing; Wang, Shibin; Li, Linan; Shen, Min; Wang, Zhiyong; Chen, Zhenfei; Zhao, Yang [Tianjin Key Laboratory of Modern Engineering Mechanics, Tianjin 300072 (China); Department of Mechanics, Tianjin University, Tianjin 300072 (China)

    2015-07-21

    A comprehensive morphological stability analysis of a nanoscale circular island during heteroepitaxial growth is presented based on continuum elasticity theory. The interplay between kinetic and thermodynamic mechanisms is revealed by including strain-related kinetic processes. In the kinetic regime, the Burton-Cabrera-Frank model is adopted to describe the growth front of the island. Together with kinetic boundary conditions, various kinetic processes including deposition flow, adatom diffusion, attachment-detachment kinetics, and the Ehrlich-Schwoebel barrier can be taken into account at the same time. In the thermodynamic regime, line tension, surface energy, and elastic energy are considered. As the strain relief in the early stages of heteroepitaxy is more complicated than commonly suggested by simple consideration of lattice mismatch, we also investigate the effects of external applied strain and elastic response due to perturbations on the island shape evolution. The analytical expressions for elastic fields induced by mismatch strain, external applied strain, and relaxation strain are presented. A systematic approach is developed to solve the system via a perturbation analysis which yields the conditions of film morphological instabilities. Consistent with previous experimental and theoretical work, parametric studies show the kinetic evolution of elastic relaxation, island morphology, and film composition under various conditions. Our present work offers an effective theoretical approach to get a comprehensive understanding of the interplay between different growth mechanisms and how to tailor the growth mode by controlling the nature of the crucial factors.

  4. Passivation of Si solar cells by hetero-epitaxial compound semiconductor coatings

    Science.gov (United States)

    Vernon, S. M.; Spitzer, M. B.; Keavney, C. J.; Haven, V. E.; Sekula, P. A.

    1986-01-01

    A development status evaluation is made for high efficiency Si solar cells, with emphasis on the suppression of the deleterious effects of surface recombination. ZnS(0.9)Se(0.1) and GaP are identified as candidates for the reduction of surface recombination. Attention is given to methods developed for the deposition of heteroepitaxial compounds designed to block minority carrier transport to the Si solar cell surface without interfering with the majority carrier flow.

  5. Intermixing in heteroepitaxial islands: fast, self-consistent calculation of the concentration profile minimizing the elastic energy

    International Nuclear Information System (INIS)

    Gatti, R; UhlIk, F; Montalenti, F

    2008-01-01

    We present a novel computational method for finding the concentration profile which minimizes the elastic energy stored in heteroepitaxial islands. Based on a suitable combination of continuum elasticity theory and configurational Monte Carlo, we show that such profiles can be readily found by a simple, yet fully self-consistent, iterative procedure. We apply the method to SiGe/Si islands, considering realistic three-dimensional shapes (pyramids, domes and barns), finding strongly non-uniform distributions of Si and Ge atoms, in qualitative agreement with several experiments. Moreover, our simulated selective-etching profiles display, in some cases, a remarkable resemblance to the experimental ones, opening intriguing questions on the interplay between kinetic, entropic and elastic effects

  6. Crystalline islands of semiconductor films

    International Nuclear Information System (INIS)

    Zmievskaya, G. I.; Bondareva, A. L.

    2011-01-01

    Silicon carbide (SiC) nucleation in the form of powder in a discharge plasma and the formation of thin film islands on a Si(100) substrate in the course of gas-phase epitaxy are simulated numerically. Models of plasma-like media and nonequilibrium processes accompanying phase transitions of the first kind (such as condensation and crystallization) in the initial fast (fluctuation) stage are described. The nonstationary evolution of nuclei size distribution functions is modeled by solving kinetic equations in partial derivatives and stochastic Ito-Stratonovich analog equations. This makes it possible to refine the formation mechanisms of microcrystalline state polytypes and calculate the nucleation rate and the initial roughness of a SiC coating.

  7. Heteroepitaxial growth of 3-5 semiconductor compounds by metal-organic chemical vapor deposition for device applications

    Science.gov (United States)

    Collis, Ward J.; Abul-Fadl, Ali

    1988-01-01

    The purpose of this research is to design, install and operate a metal-organic chemical vapor deposition system which is to be used for the epitaxial growth of 3-5 semiconductor binary compounds, and ternary and quaternary alloys. The long-term goal is to utilize this vapor phase deposition in conjunction with existing current controlled liquid phase epitaxy facilities to perform hybrid growth sequences for fabricating integrated optoelectronic devices.

  8. Spatial separation of electrons and holes for enhancing the gas-sensing property of a semiconductor: ZnO/ZnSnO3 nanorod arrays prepared by a hetero-epitaxial growth

    Science.gov (United States)

    Wang, Ying; Gao, Peng; Sha, Linna; Chi, Qianqian; Yang, Lei; Zhang, Jianjiao; Chen, Yujin; Zhang, Milin

    2018-04-01

    The construction of semiconductor composites is known as a powerful method used to realize the spatial separation of electrons and the holes in them, which can result in more electrons or holes and increase the dispersion of oxygen ions ({{{{O}}}2}- and O - ) (one of the most critical factors for their gas-sensing properties) on the surface of the semiconductor gas sensor. In this work, using 1D ZnO/ZnSnO3 nanoarrays as an example, which are prepared through a hetero-epitaxial growing process to construct a chemically bonded interface, the above strategy to attain a better semiconductor gas-sensing property has been realized. Compared with single ZnSnO3 nanotubes and no-matching ZnO/ZnSnO3 nanoarrays gas sensors, it has been proven by x-ray photoelectron spectroscopy and photoluminescence spectrum examination that the as-obtained ZnO/ZnSnO3 sensor showed a greatly increased quantity of active surface electrons with exceptional responses to trace target gases and much lower optimum working temperatures (less than about 170 °C). For example, the as-obtained ZnO/ZnSnO3 sensor exhibited an obvious response and short response/recovery time (less than 10 s) towards trace H2S gas (a detection limit down to 700 ppb). The high responses and dynamic repeatability observed in these sensors reveal that the strategy based on the as-presented electron and hole separation is reliable for improving the gas-sensing properties of semiconductors.

  9. The effect of threading dislocations on optical absorption and electron scattering in strongly mismatched heteroepitaxial III-V compound semiconductors on silicon

    CERN Document Server

    Peiner, E; Wehmann, H H

    2002-01-01

    The effect of threading dislocations on the optical and electrical properties of InP and GaAs heteroepitaxial layers on (001) silicon was investigated. Charged deep states act as scattering centres for electrons, thus affecting the electron mobility at low temperatures. The electric field arising from charged dislocations causes enhanced optical absorption at wavelengths near the fundamental absorption edge. The mean charge of the threading dislocations in GaAs/Si was found to be considerably higher than that for InP/Si. A model is described relating this effect to a regular arrangement of alpha-type 60 deg. dislocations at extended twin defects which were observed in InP/Si but were absent in GaAs/Si.

  10. Organic-organic heteroepitaxy: facts, concepts and perspectives

    Energy Technology Data Exchange (ETDEWEB)

    Moret, M.; Borghesi, A.; Fumagalli, E.; Raimondo, L.; Sassella, A. [Dipartimento di Scienza dei Materiali, Universita di Milano Bicocca, Milano (Italy); Campione, M. [Dipartimento di Scienze Geologiche e Geotecnologie, Universita di Milano Bicocca, Milano (Italy)

    2011-08-15

    Organic-organic heteroepitaxy can represent the winning technique for growing crystalline and oriented heterostructures of organic semiconductors. However, a sound physical interpretation of mechanisms that control epitaxy is still missing for these low symmetry molecular systems, generally not obeying the usual lattice matching rules for inorganic systems. We discuss here a couple of paradigmatic examples of organic-organic heteroepitaxy suggesting a possible physical rationale for the formation of the heterostructure interfaces as it arises from experimental characterization and computer modeling with atom-atom potential simulations. (copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  11. Semiconductor

    International Nuclear Information System (INIS)

    2000-01-01

    This book deals with process and measurement of semiconductor. It contains 20 chapters, which goes as follows; semiconductor industry, introduction of semiconductor manufacturing, yield of semiconductor process, materials, crystal growth and a wafer forming, PN, control pollution, oxidation, photomasking photoresist chemistry, photomasking technologies, diffusion and ion injection, chemical vapor deposition, metallization, wafer test and way of evaluation, semiconductor elements, integrated circuit and semiconductor circuit technology.

  12. Dislocation-free Ge Nano-crystals via Pattern Independent Selective Ge Heteroepitaxy on Si Nano-Tip Wafers.

    Science.gov (United States)

    Niu, Gang; Capellini, Giovanni; Schubert, Markus Andreas; Niermann, Tore; Zaumseil, Peter; Katzer, Jens; Krause, Hans-Michael; Skibitzki, Oliver; Lehmann, Michael; Xie, Ya-Hong; von Känel, Hans; Schroeder, Thomas

    2016-03-04

    The integration of dislocation-free Ge nano-islands was realized via selective molecular beam epitaxy on Si nano-tip patterned substrates. The Si-tip wafers feature a rectangular array of nanometer sized Si tips with (001) facet exposed among a SiO2 matrix. These wafers were fabricated by complementary metal-oxide-semiconductor (CMOS) compatible nanotechnology. Calculations based on nucleation theory predict that the selective growth occurs close to thermodynamic equilibrium, where condensation of Ge adatoms on SiO2 is disfavored due to the extremely short re-evaporation time and diffusion length. The growth selectivity is ensured by the desorption-limited growth regime leading to the observed pattern independence, i.e. the absence of loading effect commonly encountered in chemical vapor deposition. The growth condition of high temperature and low deposition rate is responsible for the observed high crystalline quality of the Ge islands which is also associated with negligible Si-Ge intermixing owing to geometric hindrance by the Si nano-tip approach. Single island as well as area-averaged characterization methods demonstrate that Ge islands are dislocation-free and heteroepitaxial strain is fully relaxed. Such well-ordered high quality Ge islands present a step towards the achievement of materials suitable for optical applications.

  13. Study of low dimensional SiGe island on Si for potential visible Metal-Semiconductor-Metal photodetector

    Science.gov (United States)

    Rahim, Alhan Farhanah Abd; Zainal Badri, Nur'Amirah; Radzali, Rosfariza; Mahmood, Ainorkhilah

    2017-11-01

    In this paper, an investigation of design and simulation of silicon germanium (SiGe) islands on silicon (Si) was presented for potential visible metal semiconductor metal (MSM) photodetector. The characterization of the performances in term of the structural, optical and electrical properties of the structures was analyzed from the simulation results. The project involves simulation using SILVACO Technology Computer Aided Design (TCAD) tools. The different structures of the silicon germanium (SiGe) island on silicon substrate were created, which were large SiGe, small SiGe, combination SiGe and bulk Ge. All the structures were tested for potential Metal Semiconductor Metal (MSM) photodetector. The extracted data such as current versus voltage characteristic, current gain and spectral response were obtained using ATLAS SILVACO tools. The performance of SiGe island structures and bulk Ge on Si substrate as (MSM) photodetector was evaluated by photo and dark current-voltage (I-V) characteristics. It was found that SiGe islands exhibited higher energy band gap compared to bulk Ge. The SiGe islands current-voltage characteristics showed improved current gain compared to bulk Ge. Specifically the enhancement of the islands gain was contributed by the enhanced photo currents and lower dark currents. The spectral responses of the SiGe islands showed peak response at 590 nm (yellow) which is at the visible wavelength. This shows the feasibility of the SiGe islands to be utilized for visible photodetections.

  14. Study of low dimensional SiGe island on Si for potential visible Metal-Semiconductor-Metal photodetector

    Directory of Open Access Journals (Sweden)

    Abd Rahim Alhan Farhanah

    2017-01-01

    Full Text Available In this paper, an investigation of design and simulation of silicon germanium (SiGe islands on silicon (Si was presented for potential visible metal semiconductor metal (MSM photodetector. The characterization of the performances in term of the structural, optical and electrical properties of the structures was analyzed from the simulation results. The project involves simulation using SILVACO Technology Computer Aided Design (TCAD tools. The different structures of the silicon germanium (SiGe island on silicon substrate were created, which were large SiGe, small SiGe, combination SiGe and bulk Ge. All the structures were tested for potential Metal Semiconductor Metal (MSM photodetector. The extracted data such as current versus voltage characteristic, current gain and spectral response were obtained using ATLAS SILVACO tools. The performance of SiGe island structures and bulk Ge on Si substrate as (MSM photodetector was evaluated by photo and dark current-voltage (I-V characteristics. It was found that SiGe islands exhibited higher energy band gap compared to bulk Ge. The SiGe islands current-voltage characteristics showed improved current gain compared to bulk Ge. Specifically the enhancement of the islands gain was contributed by the enhanced photo currents and lower dark currents. The spectral responses of the SiGe islands showed peak response at 590 nm (yellow which is at the visible wavelength. This shows the feasibility of the SiGe islands to be utilized for visible photodetections.

  15. Structural characterization of self-assembled semiconductor islands by three-dimensional X-ray diffraction mapping in reciprocal space

    International Nuclear Information System (INIS)

    Holy, V.; Mundboth, K.; Mokuta, C.; Metzger, T.H.; Stangl, J.; Bauer, G.; Boeck, T.; Schmidbauer, M.

    2008-01-01

    For the first time self-organized epitaxially grown semiconductor islands were investigated by a full three-dimensional mapping of the scattered X-ray intensity in reciprocal space. Intensity distributions were measured in a coplanar diffraction geometry around symmetric and asymmetric Bragg reflections. The 3D intensity maps were compared with theoretical simulations based on continuum-elasticity simulations of internal strains in the islands and on kinematical scattering theory whereby local chemical composition and strain profiles of the islands were retrieved

  16. Anisotropic Growth of Otavite on Calcite: Implications for Heteroepitaxial Growth Mechanisms

    Energy Technology Data Exchange (ETDEWEB)

    Riechers, Shawn L.; Kerisit, Sebastien N.

    2017-12-18

    Elucidating how cation intermixing can affect the mechanisms of heteroepitaxial growth in aqueous media has remained a challenging endeavor. Toward this goal, in situ atomic force microscopy was employed to image the heteroepitaxial growth of otavite (CdCO3) at the (10-14) surface of calcite (CaCO3) single crystals in static aqueous conditions. Heteroepitaxial growth proceeded via spreading of three-dimensional (3D) islands and two-dimensional (2D) atomic layers at low and high initial saturation levels, respectively. Experiments were carried out as a function of applied force and imaging mode thus enabling determination of growth mechanisms unaltered by imaging artifacts. This approach revealed the significant anisotropic nature of heteroepitaxial growth on calcite in both growth modes and its dependence on supersaturation, intermixing, and substrate topography. The 3D islands not only grew preferentially along the [42-1] direction relative to the [010] direction, resulting in rod-like surface precipitates, but also showed clear preference for growth from the island end rich in obtuse/obtuse kink sites. Pinning to step edges was observed to often reverse this tendency. In the 2D growth mode, the relative velocities of acute and obtuse steps were observed to switch between the first and second atomic layers. This phenomenon stemmed from the significant Cd-Ca intermixing in the first layer, despite bulk thermodynamics predicting the formation of almost pure otavite. Composition effects were also responsible for the inability of 3D islands to grow on 2D layers in cases where both modes were observed to occur simultaneously. Overall, the AFM images highlighted the effects of intermixing on heteroepitaxial growth, particularly how it can induce thickness-dependent growth mechanisms at the nanoscale.

  17. A novel planar vertical double-diffused metal-oxide-semiconductor field-effect transistor with inhomogeneous floating islands

    International Nuclear Information System (INIS)

    Ren Min; Li Ze-Hong; Liu Xiao-Long; Xie Jia-Xiong; Deng Guang-Min; Zhang Bo

    2011-01-01

    A novel planar vertical double-diffused metal-oxide-semiconductor (VDMOS) structure with an ultra-low specific on-resistance (R on,sp ), whose distinctive feature is the use of inhomogeneous floating p-islands in the n-drift region, is proposed. The theoretical limit of its R on,sp is deduced, the influence of structure parameters on the breakdown voltage (BV) and R on,sp are investigated, and the optimized results with BV of 83 V and R on,sp of 54 mΩ·mm 2 are obtained. Simulations show that the inhomogeneous-floating-islands metal-oxide-semiconductor field-effect transistor (MOSFET) has a superior 'R on,sp /BV' trade-off to the conventional VDMOS (a 38% reduction of R on,sp with the same BV) and the homogeneous-floating-islands MOSFET (a 10% reduction of R on,sp with the same BV). The inhomogeneous-floating-islands MOSFET also has a much better body-diode characteristic than the superjunction MOSFET. Its reverse recovery peak current, reverse recovery time and reverse recovery charge are about 50, 80 and 40% of those of the superjunction MOSFET, respectively. (interdisciplinary physics and related areas of science and technology)

  18. Modeling elastic anisotropy in strained heteroepitaxy.

    Science.gov (United States)

    Dixit, Gopal Krishna; Ranganathan, Madhav

    2017-09-20

    Using a continuum evolution equation, we model the growth and evolution of quantum dots in the heteroepitaxial Ge on Si(0 0 1) system in a molecular beam epitaxy unit. We formulate our model in terms of evolution due to deposition, and due to surface diffusion which is governed by a free energy. This free energy has contributions from surface energy, curvature, wetting effects and elastic energy due to lattice mismatch between the film and the substrate. In addition to anisotropy due to surface energy which favors facet formation, we also incorporate elastic anisotropy due to an underlying crystal lattice. The complicated elastic problem of the film-substrate system subjected to boundary conditions at the free surface, interface and the bulk substrate is solved by perturbation analysis using a small slope approximation. This permits an analysis of effects at different orders in the slope and sheds new light on the observed behavior. Linear stability analysis shows the early evolution of the instability towards dot formation. The elastic anisotropy causes a change in the alignment of dots in the linear regime, whereas the surface energy anisotropy changes the dot shapes at the nonlinear regime. Numerical simulation of the full nonlinear equations shows the evolution of the surface morphology. In particular, we show, for parameters of the [Formula: see text] [Formula: see text] on Si(0 0 1), the surface energy anisotropy dominates the shapes of the quantum dots, whereas their alignment is influenced by the elastic energy anisotropy. The anisotropy in elasticity causes a further elongation of the islands whose coarsening is interrupted due to [Formula: see text] facets on the surface.

  19. Modeling elastic anisotropy in strained heteroepitaxy

    Science.gov (United States)

    Krishna Dixit, Gopal; Ranganathan, Madhav

    2017-09-01

    Using a continuum evolution equation, we model the growth and evolution of quantum dots in the heteroepitaxial Ge on Si(0 0 1) system in a molecular beam epitaxy unit. We formulate our model in terms of evolution due to deposition, and due to surface diffusion which is governed by a free energy. This free energy has contributions from surface energy, curvature, wetting effects and elastic energy due to lattice mismatch between the film and the substrate. In addition to anisotropy due to surface energy which favors facet formation, we also incorporate elastic anisotropy due to an underlying crystal lattice. The complicated elastic problem of the film-substrate system subjected to boundary conditions at the free surface, interface and the bulk substrate is solved by perturbation analysis using a small slope approximation. This permits an analysis of effects at different orders in the slope and sheds new light on the observed behavior. Linear stability analysis shows the early evolution of the instability towards dot formation. The elastic anisotropy causes a change in the alignment of dots in the linear regime, whereas the surface energy anisotropy changes the dot shapes at the nonlinear regime. Numerical simulation of the full nonlinear equations shows the evolution of the surface morphology. In particular, we show, for parameters of the Ge0.25 Si0.75 on Si(0 0 1), the surface energy anisotropy dominates the shapes of the quantum dots, whereas their alignment is influenced by the elastic energy anisotropy. The anisotropy in elasticity causes a further elongation of the islands whose coarsening is interrupted due to facets on the surface.

  20. Low-coverage heteroepitaxial growth with interfacial mixing

    Science.gov (United States)

    Mazzitello, K. I.; Delgado, L. M.; Iguain, J. L.

    2015-01-01

    We investigate the influence of intermixing on heteroepitaxial growth dynamics, using a two-dimensional point island model, expected to be a good approximation in the early stages of epitaxy. In this model, which we explore both analytically and numerically, every deposited B atom diffuses on the surface with diffusion constant DB and can exchange with any A atom of the substrate at constant rate. There is no exchange back and emerging atoms diffuse on the surface with diffusion constant DA. When any two diffusing atoms meet, they nucleate a point island. The islands neither diffuse nor break and grow by capturing other diffusing atoms. The model leads to an island density governed by the diffusion of one of the species at low temperature and by the diffusion of the other at high temperature. We show that these limit behaviors, as well as intermediate ones, all belong to the same universality class, described by a scaling law. We also show that the island-size distribution is self-similarly described by a dynamic scaling law in the limits where only one diffusion constant is relevant to the dynamics and that this law is affected when both DA and DB play a role.

  1. Low-coverage heteroepitaxial growth with interfacial mixing

    International Nuclear Information System (INIS)

    Mazzitello, K I; Delgado, L M; Iguain, J L

    2015-01-01

    We investigate the influence of intermixing on heteroepitaxial growth dynamics, using a two-dimensional point island model, expected to be a good approximation in the early stages of epitaxy. In this model, which we explore both analytically and numerically, every deposited B atom diffuses on the surface with diffusion constant D B and can exchange with any A atom of the substrate at constant rate. There is no exchange back and emerging atoms diffuse on the surface with diffusion constant D A . When any two diffusing atoms meet, they nucleate a point island. The islands neither diffuse nor break and grow by capturing other diffusing atoms. The model leads to an island density governed by the diffusion of one of the species at low temperature and by the diffusion of the other at high temperature. We show that these limit behaviors, as well as intermediate ones, all belong to the same universality class, described by a scaling law. We also show that the island-size distribution is self-similarly described by a dynamic scaling law in the limits where only one diffusion constant is relevant to the dynamics and that this law is affected when both D A and D B play a role. (paper)

  2. A novel planar vertical double-diffused metal-oxide-semiconductor field-effect transistor with inhomogeneous floating islands

    Institute of Scientific and Technical Information of China (English)

    Ren Min; Li Ze-Hong; Liu Xiao-Long; Xie Jia-Xiong; Deng Guang-Min; Zhang Bo

    2011-01-01

    A novel planar vertical double-diffused metal-oxide-semiconductor (VDMOS) structure with an ultra-low specific on-resistance (Ron,sp),whose distinctive feature is the use of inhomogeneous floating p-islands in the n-drift region,is proposed.The theoretical limit of its Ron,sp is deduced,the influence of structure parameters on the breakdown voltage (BV) and Ron,sp are investigated,and the optimized results with BV of 83 V and Ron,sp of 54 mΩ.mm2 are obtained.Simulations show that the inhomogencous-floating-islands metal-oxide-semiconductor field-effect transistor (MOSFET)has a superior “Ron,sp/BV” trade-off to the conventional VDMOS (a 38% reduction of Ron,sp with the same BV) and the homogeneous-floating-islands MOSFET (a 10% reduction of Ron,sp with the same BV).The inhomogeneous-floatingislands MOSFET also has a much better body-diode characteristic than the superjunction MOSFET.Its reverse recovery peak current,reverse recovery time and reverse recovery charge are about 50,80 and 40% of those of the superjunction MOSFET,respectively.

  3. Monte Carlo determination of heteroepitaxial misfit structures

    DEFF Research Database (Denmark)

    Baker, J.; Lindgård, Per-Anker

    1996-01-01

    We use Monte Carlo simulations to determine the structure of KBr overlayers on a NaCl(001) substrate, a system with large (17%) heteroepitaxial misfit. The equilibrium relaxation structure is determined for films of 2-6 ML, for which extensive helium-atom scattering data exist for comparison...

  4. Direct evidence of strain transfer for InAs island growth on compliant Si substrates

    Energy Technology Data Exchange (ETDEWEB)

    Marçal, L. A. B.; Magalhães-Paniago, R.; Malachias, Angelo, E-mail: angeloms@fisica.ufmg.br [Universidade Federal de Minas Gerais, Av. Antonio Carlos 6627, CEP 31270-901, Belo Horizonte (Brazil); Richard, M.-I. [European Synchrotron (ESRF), ID01 beamline, CS 40220, 38043 Grenoble Cedex 9 (France); Aix-Marseille University, IM2NP-CNRS, Faculté des Sciences de St Jérôme, 13397 Marseille (France); Cavallo, F. [Center for High Technology Materials, University of New Mexico, 1313 Goddard St., Albuquerque, New Mexico 87106 (United States); University of Wisconsin-Madison, 1500 Engineering Drive, Madison, Wisconsin 53706 (United States); Lagally, M. G. [University of Wisconsin-Madison, 1500 Engineering Drive, Madison, Wisconsin 53706 (United States); Schmidt, O. G. [Institute for Integrative Nanosciences, IFW-Dresden, D-01171 Dresden (Germany); Schülli, T. Ü. [European Synchrotron (ESRF), ID01 beamline, CS 40220, 38043 Grenoble Cedex 9 (France); Deneke, Ch. [Laboratório Nacional de Nanotecnologia (LNNano/CNPEM), C.P. 6192, CEP 13083-970, Campinas (Brazil)

    2015-04-13

    Semiconductor heteroepitaxy on top of thin compliant layers has been explored as a path to make inorganic electronics mechanically flexible as well as to integrate materials that cannot be grown directly on rigid substrates. Here, we show direct evidences of strain transfer for InAs islands on freestanding Si thin films (7 nm). Synchrotron X-ray diffraction measurements using a beam size of 300 × 700 nm{sup 2} can directly probe the strain status of the compliant substrate underneath deposited islands. Using a recently developed diffraction mapping technique, three-dimensional reciprocal space maps were reconstructed around the Si (004) peak for specific illuminated positions of the sample. The strain retrieved was analyzed using continuous elasticity theory via Finite-element simulations. The comparison of experiment and simulations yields the amount of strain from the InAs islands, which is transferred to the compliant Si thin film.

  5. Shaping the composition profiles in heteroepitaxial quantum dots: Interplay of thermodynamic and kinetic effects

    Directory of Open Access Journals (Sweden)

    C. Georgiou

    2014-07-01

    Full Text Available Atomistic Monte Carlo simulations, coupling thermodynamic and kinetic effects, resolve a longstanding controversy regarding the origin of composition profiles in heteroepitaxial SiGe quantum dots. It is shown that profiles with cores rich in the unstrained (Si component derive from near-equilibrium processes and intraisland diffusion. Profiles with cores rich in the strained (Ge component are of nonequilibrium nature, i.e., they are strain driven but kinetically limited. They are shaped by the distribution of kinetic barriers of atomic diffusion in the islands. The diffusion pathways are clearly revealed for the first time. Geometrical kinetics play a minor role.

  6. Radiation effects in heteroepitaxial InP solar cells

    Science.gov (United States)

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

    1993-01-01

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

  7. Structure and optical properties of cored wurtzite (Zn,Mg)O heteroepitaxial nanowires

    International Nuclear Information System (INIS)

    Heo, Y.W.; Abernathy, C.; Pruessner, K.; Sigmund, W.; Norton, D.P.; Overberg, M.; Ren, F.; Chisholm, M.F.

    2004-01-01

    The synthesis, structure, and optical properties of one-dimensional heteroepitaxial cored (Zn,Mg)O semiconductor nanowires grown by a catalyst-driven molecular beam epitaxy technique are discussed. The structures form spontaneously in a Zn, Mg and O 2 /O 3 flux, consisting of a single crystal, Zn-rich Zn 1-x Mg x O(x 1-y Mg y O(y>>0.02) sheath. High resolution Z-contrast scanning transmission electron microscopy shows core diameters as small as 4 nm. The cored structure forms spontaneously under constant flux due to a bimodal growth mechanism in which the core forms via bulk like vapor-liquid-solid growth, while the outer sheath grows as a heteroepitaxial layer. Temperature-dependent photoluminescence shows a slight blueshift in the near band edge peak, which is attributed to a few percent Mg doping in the nanoscale ZnO core. The catalyst-driven molecular beam epitaxy technique provides for site-specific nanorod growth on arbitrary substrates

  8. Heteroepitaxially grown InP solar cells

    International Nuclear Information System (INIS)

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

    1990-01-01

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

  9. Facile Five-Step Heteroepitaxial Growth of GaAs Nanowires on Silicon Substrates and the Twin Formation Mechanism.

    Science.gov (United States)

    Yao, Maoqing; Sheng, Chunyang; Ge, Mingyuan; Chi, Chun-Yung; Cong, Sen; Nakano, Aiichiro; Dapkus, P Daniel; Zhou, Chongwu

    2016-02-23

    Monolithic integration of III-V semiconductors with Si has been pursued for some time in the semiconductor industry. However, the mismatch of lattice constants and thermal expansion coefficients represents a large technological challenge for the heteroepitaxial growth. Nanowires, due to their small lateral dimension, can relieve strain and mitigate dislocation formation to allow single-crystal III-V materials to be grown on Si. Here, we report a facile five-step heteroepitaxial growth of GaAs nanowires on Si using selective area growth (SAG) in metalorganic chemical vapor deposition, and we further report an in-depth study on the twin formation mechanism. Rotational twin defects were observed in the nanowire structures and showed strong dependence on the growth condition and nanowire size. We adopt a model of faceted growth to demonstrate the formation of twins during growth, which is well supported by both a transmission electron microscopy study and simulation based on nucleation energetics. Our study has led to twin-free segments in the length up to 80 nm, a significant improvement compared to previous work using SAG. The achievements may open up opportunities for future functional III-V-on-Si heterostructure devices.

  10. Large-area, laterally-grown epitaxial semiconductor layers

    Science.gov (United States)

    Han, Jung; Song, Jie; Chen, Danti

    2017-07-18

    Structures and methods for confined lateral-guided growth of a large-area semiconductor layer on an insulating layer are described. The semiconductor layer may be formed by heteroepitaxial growth from a selective growth area in a vertically-confined, lateral-growth guiding structure. Lateral-growth guiding structures may be formed in arrays over a region of a substrate, so as to cover a majority of the substrate region with laterally-grown epitaxial semiconductor tiles. Quality regions of low-defect, stress-free GaN may be grown on silicon.

  11. Ion beam synthesis and characterization of large area 3C-SiC pseudo substrates for homo- and heteroepitaxy; Ionenstrahlsynthese und Charakterisierung grossflaechiger 3C-SiC-Pseudosubstrate fuer die Homo- und Heteroepitaxie

    Energy Technology Data Exchange (ETDEWEB)

    Haeberlen, Maik

    2006-12-15

    In this work, large area epitaxial 3C-SiC films on Si(100) and Si(111) were formed by ion beam synthesis and subsequently characterized for their structural and crystalline properties. These SiC/Si structures are meant to be used as SiC pseudosubstrates for the homo- and heteroepitaxial growth of other compound semiconductors. The suitability of these pseudosubstrates for this purpose was tested using various epitaxial systems and thin film growth methods. For this the homoepitaxial growth of 3C-SiC employing C{sub 60}-MBE and the heteroepitaxial growth of hexagonal GaN films grown by MOCVD and IBAMBA was studied in detail. The comparison of the structural and crystalline properties with data from literature enabled a qualified judgement of the potential of the 3C-SiC pseudosubstrates as an alternative substrate for the epitaxial growth of such films. These new 3C-SiC pseudosubstrates also enabled studies of other little known epitaxial systems: For the first time hexagonal ZnO films on (111) oriented pseudosubstrates were grown using PLD. The method if IBAMBE enabled the growth of cubic GaN layers on (100)-oriented pseudosubstrates. (orig.)

  12. Defects in large-MISFIT heteroepitaxy

    International Nuclear Information System (INIS)

    Eaglesham, D.J.; Aindow, M.; Pond, R.C.

    1988-01-01

    A transmission electron microcopy (TEM) study is presented on GaAs on Si (100) and CdTe on GaAs (100), and the implications for defect nucleation mechanisms are discussed. MOCVD GaAs/Si is shown to grow by island nucleation followed by 3D growth. Single islands are free of inversion domain boundaries (or APBs) implying that a single domain is able to grow over a demi-step on the substrate surface during this 3D growth. MISFIT dislocations are shown to be edge type during island growth, with 60 degrees type being generated at island junctions. The predominant threading dislocations are found to have inclined a/2 left-angle 110 right-angle Burgers vectors. The implied mechanisms for the generation of both MISFIT and threading dislocations are discussed. In MOCVD CdTe/GaAs the microstructure is shown to have a number of qualitatively similar features; in addition, study of this much larger MISFIT system allows the authors to deduce a possible explanation for misorientation effects in these systems

  13. Controlling the optical properties of monocrystalline 3C-SiC heteroepitaxially grown on silicon at low temperatures

    Science.gov (United States)

    Colston, Gerard; Myronov, Maksym

    2017-11-01

    Cubic silicon carbide (3C-SiC) offers an alternative wide bandgap semiconductor to conventional materials such as hexagonal silicon carbide (4H-SiC) or gallium nitride (GaN) for the detection of UV light and can offer a closely lattice matched virtual substrate for subsequent GaN heteroepitaxy. As 3C-SiC can be heteroepitaxially grown on silicon (Si) substrates its optical properties can be manipulated by controlling the thickness and doping concentrations. The optical properties of 3C-SiC epilayers have been characterized by measuring the transmission of light through suspended membranes. Decreasing the thickness of the 3C-SiC epilayers is shown to shift the absorbance edge to lower wavelengths, a result of the indirect bandgap nature of silicon carbide. This property, among others, can be exploited to fabricate very low-cost, tuneable 3C-SiC based UV photodetectors. This study investigates the effect of thickness and doping concentration on the optical properties of 3C-SiC epilayers grown at low temperatures by a standard Si based growth process. The results demonstrate the potential photonic applications of 3C-SiC and its heterogeneous integration into the Si industry.

  14. Ion beam synthesis and characterization of large area 3C-SiC pseudo substrates for homo- and heteroepitaxy

    International Nuclear Information System (INIS)

    Haeberlen, Maik

    2006-12-01

    In this work, large area epitaxial 3C-SiC films on Si(100) and Si(111) were formed by ion beam synthesis and subsequently characterized for their structural and crystalline properties. These SiC/Si structures are meant to be used as SiC pseudosubstrates for the homo- and heteroepitaxial growth of other compound semiconductors. The suitability of these pseudosubstrates for this purpose was tested using various epitaxial systems and thin film growth methods. For this the homoepitaxial growth of 3C-SiC employing C 60 -MBE and the heteroepitaxial growth of hexagonal GaN films grown by MOCVD and IBAMBA was studied in detail. The comparison of the structural and crystalline properties with data from literature enabled a qualified judgement of the potential of the 3C-SiC pseudosubstrates as an alternative substrate for the epitaxial growth of such films. These new 3C-SiC pseudosubstrates also enabled studies of other little known epitaxial systems: For the first time hexagonal ZnO films on (111) oriented pseudosubstrates were grown using PLD. The method if IBAMBE enabled the growth of cubic GaN layers on (100)-oriented pseudosubstrates. (orig.)

  15. Electrical leakage phenomenon in heteroepitaxial cubic silicon carbide on silicon

    Science.gov (United States)

    Pradeepkumar, Aiswarya; Zielinski, Marcin; Bosi, Matteo; Verzellesi, Giovanni; Gaskill, D. Kurt; Iacopi, Francesca

    2018-06-01

    Heteroepitaxial 3C-SiC films on silicon substrates are of technological interest as enablers to integrate the excellent electrical, electronic, mechanical, thermal, and epitaxial properties of bulk silicon carbide into well-established silicon technologies. One critical bottleneck of this integration is the establishment of a stable and reliable electronic junction at the heteroepitaxial interface of the n-type SiC with the silicon substrate. We have thus investigated in detail the electrical and transport properties of heteroepitaxial cubic silicon carbide films grown via different methods on low-doped and high-resistivity silicon substrates by using van der Pauw Hall and transfer length measurements as test vehicles. We have found that Si and C intermixing upon or after growth, particularly by the diffusion of carbon into the silicon matrix, creates extensive interstitial carbon traps and hampers the formation of a stable rectifying or insulating junction at the SiC/Si interface. Although a reliable p-n junction may not be realistic in the SiC/Si system, we can achieve, from a point of view of the electrical isolation of in-plane SiC structures, leakage suppression through the substrate by using a high-resistivity silicon substrate coupled with deep recess etching in between the SiC structures.

  16. Strain relaxation studies of the Fe3O4/MgO (100) heteroepitaxial system grown by magnetron sputtering

    International Nuclear Information System (INIS)

    Balakrishnan, K; Arora, S K; Shvets, I V

    2004-01-01

    Detailed strain relaxation studies of epitaxial magnetite, Fe 3 O 4 , films on MgO(100) substrates grown by magnetron sputtering reveal the accommodation of strain up to 600 nm thickness, a thickness far above the critical thickness (t c ) predicted by theoretical models. The results are in agreement with the suggestion that the excess strain in Fe 3 O 4 /MgO (100) heteroepitaxy is accommodated by the presence of antiphase boundaries. The compressive strain generated by the antiphase boundaries compensates for the tensile strain within the growth islands, allowing the film to remain fully coherent with the substrate. Contrary to earlier findings, magnetization decreases with an increase in the film thickness. This vindicates the view that the structure of the antiphase boundaries depends on the growth conditions

  17. Heteroepitaxial Ge-on-Si by DC magnetron sputtering

    Directory of Open Access Journals (Sweden)

    Martin Steglich

    2013-07-01

    Full Text Available The growth of Ge on Si(100 by DC Magnetron Sputtering at various temperatures is studied by Spectroscopic Ellipsometry and Transmission Electron Microscopy. Smooth heteroepitaxial Ge films are prepared at relatively low temperatures of 380°C. Typical Stransky-Krastanov growth is observed at 410°C. At lower temperatures (320°C, films are essentially amorphous with isolated nanocrystallites at the Si-Ge interface. A minor oxygen contamination at the interface, developing after ex-situ oxide removal, is not seen to hinder epitaxy. Compensation of dislocation-induced acceptors in Ge by sputtering from n-doped targets is proposed.

  18. Automation and Integration in Semiconductor Manufacturing

    OpenAIRE

    Liao, Da-Yin

    2010-01-01

    Semiconductor automation originates from the prevention and avoidance of frauds in daily fab operations. As semiconductor technology and business continuously advance and grow, manufacturing systems must aggressively evolve to meet the changing technical and business requirements in this industry. Semiconductor manufacturing has been suffering pains from islands of automation. The problems associated with these systems are limited

  19. Heteroepitaxy of orientation-patterned nonlinear optical materials

    Science.gov (United States)

    Tassev, Vladimir L.; Vangala, Shivashankar R.; Peterson, Rita D.; Snure, Michael

    2018-03-01

    We report some recent results on thick heteroepitaxial growth of GaP on GaAs substrates and on orientation-patterned (OP) GaAs templates conducted in a hot-wall horizontal quartz reactor for Hydride Vapor Phase Epitaxy. The growths on the plain substrates resulted in up to 500 μm thick GaP with smooth surface morphology (RMS following stages of growth, as well on the mechanisms of the strain relaxation from the lattice and thermal mismatch between layer and substrate. The efforts to accommodate the growing film to the foreign substrate by engineering an intermediate buffer layer were extended to thick growths of GaAsxP1-x ternary with the idea to combine in one material the best of the nonlinear properties of GaP and GaAs that are strictly relevant to the pursued applications.

  20. 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.

  1. Semiconductor physics

    CERN Document Server

    Böer, Karl W

    2018-01-01

    This handbook gives a complete survey of the important topics and results in semiconductor physics. It addresses every fundamental principle and most research topics and areas of application in the field of semiconductor physics. Comprehensive information is provided on crystalline bulk and low-dimensional as well as amporphous semiconductors, including optical, transport, and dynamic properties.

  2. Nanoporous Silica Templated HeteroEpitaxy: Final LDRD Report.

    Energy Technology Data Exchange (ETDEWEB)

    Burckel, David Bruce; Koleske, Daniel; Rowen, Adam M.; Williams, John Dalton; Fan, Hongyou; Arrington, Christian Lew

    2006-11-01

    This one-year out-of-the-box LDRD was focused on exploring the use of porous growth masks as a method for defect reduction during heteroepitaxial crystal growth. Initially our goal was to investigate porous silica as a growth mask, however, we expanded the scope of the research to include several other porous growth masks on various size scales, including mesoporous carbon, and the UV curable epoxy, SU-8. Use of SU-8 as a growth mask represents a new direction, unique in the extensive literature of patterned epitaxial growth, and presents the possibility of providing a single step growth mask. Additional research included investigation of pore viability via electrochemical deposition into high aspect ratio photoresist patterns and pilot work on using SU-8 as a DUV negative resist, another significant potential result. While the late start nature of this project pushed some of the initial research goals out of the time table, significant progress was made. 3 Acknowledgements This work was performed in part at the Nanoscience @ UNM facility, a member of the National Nanotechnology Infrastructure Network, which is supported by the National Science Foundation (Grant ECS 03-35765). Sandia is multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United Stated Department of Energy's National Nuclear Security Administration under Contract DE-AC04-94AL85000. This work was supported under the Sandia LDRD program (Project 99405). 4

  3. Polarity Control of Heteroepitaxial GaN Nanowires on Diamond.

    Science.gov (United States)

    Hetzl, Martin; Kraut, Max; Hoffmann, Theresa; Stutzmann, Martin

    2017-06-14

    Group III-nitride materials such as GaN nanowires are characterized by a spontaneous polarization within the crystal. The sign of the resulting sheet charge at the top and bottom facet of a GaN nanowire is determined by the orientation of the wurtzite bilayer of the different atomic species, called N and Ga polarity. We investigate the polarity distribution of heteroepitaxial GaN nanowires on different substrates and demonstrate polarity control of GaN nanowires on diamond. Kelvin Probe Force Microscopy is used to determine the polarity of individual selective area-grown and self-assembled nanowires over a large scale. At standard growth conditions, mixed polarity occurs for selective GaN nanowires on various substrates, namely on silicon, on sapphire and on diamond. To obtain control over the growth orientation on diamond, the substrate surface is modified by nitrogen and oxygen plasma exposure prior to growth, and the growth parameters are adjusted simultaneously. We find that the surface chemistry and the substrate temperature are the decisive factors for obtaining control of up to 93% for both polarity types, whereas the growth mode, namely selective area or self-assembled growth, does not influence the polarity distribution significantly. The experimental results are discussed by a model based on the interfacial bonds between the GaN nanowires, the termination layer, and the substrate.

  4. Homo- and heteroepitaxial growth behavior of upright InAs nanowires on InAs and GaAs substrates

    Energy Technology Data Exchange (ETDEWEB)

    Bauer, Jens; Gottschalch, Volker; Paetzelt, Hendrik [Institut fuer Anorganische Chemie, Universitaet Leipzig, Johannesallee 29, D-04103 Leipzig (Germany); Wagner, Gerald [Institut fuer Kristallographie und Mineralogie, Universitaet Leipzig, Linnestr. 5, D-04103 Leipzig (Germany); Pietsch, Ulrich [Festkoerperphysik, Universitaet Siegen, D-57068 Siegen (Germany)

    2008-07-01

    Semiconductor nanowires (NW) acquire recently attraction because of promising new application fields in electronics and optoelectronic. We applied the vapor-liquid-solid mechanism with gold seeds in combination with low-pressure metal-organic vapor phase epitaxy (LP-MOVPE) to achieve replicable InAs NW growth with high growth rates. Since the initial alloying of the gold seeds with the substrate material plays a deciding role for the inceptive NW growth, InAs free standing nanowires were grown on GaAs(111)B substrate as well as on InAs/GaAs(111)B quasi-substrate. The influence of the MOVPE parameters will be discussed with respect to NW morphology and real-structure. A special focus will be set on the heteroepitaxial InAs NW growth on GaAs substrates. Gracing-incidence X-ray studies and transmission electron microscopy investigations revealed the existence of a thin Ga{sub x}In{sub 1-x}As graduated alloy layer with embedded crystalline gold alloy particles at the NW substrate interface. The effect of droplet composition on the VLS growth will be presented in a thermodynamic model.

  5. Si Complies with GaN to Overcome Thermal Mismatches for the Heteroepitaxy of Thick GaN on Si.

    Science.gov (United States)

    Tanaka, Atsunori; Choi, Woojin; Chen, Renjie; Dayeh, Shadi A

    2017-10-01

    Heteroepitaxial growth of lattice mismatched materials has advanced through the epitaxy of thin coherently strained layers, the strain sharing in virtual and nanoscale substrates, and the growth of thick films with intermediate strain-relaxed buffer layers. However, the thermal mismatch is not completely resolved in highly mismatched systems such as in GaN-on-Si. Here, geometrical effects and surface faceting to dilate thermal stresses at the surface of selectively grown epitaxial GaN layers on Si are exploited. The growth of thick (19 µm), crack-free, and pure GaN layers on Si with the lowest threading dislocation density of 1.1 × 10 7 cm -2 achieved to date in GaN-on-Si is demonstrated. With these advances, the first vertical GaN metal-insulator-semiconductor field-effect transistors on Si substrates with low leakage currents and high on/off ratios paving the way for a cost-effective high power device paradigm on an Si CMOS platform are demonstrated. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Proceedings of wide band gap semiconductors

    International Nuclear Information System (INIS)

    Moustakas, T.D.; Pankove, J.I.; Hamakawa, Y.

    1992-01-01

    This book contains the proceedings of wide band gap semiconductors. Wide band gap semiconductors are under intense study because of their potential applications in photonic devices in the visible and ultraviolet part of the electromagnetic spectrum, and devices for high temperature, high frequency and high power electronics. Additionally, due to their unique mechanical, thermal, optical, chemical, and electronic properties many wide band gap semiconductors are anticipated to find applications in thermoelectric, electrooptic, piezoelectric and acoustooptic devices as well as protective coatings, hard coatings and heat sinks. Material systems covered in this symposium include diamond, II-VI compounds, III-V nitrides, silicon carbide, boron compounds, amorphous and microcrystalline semiconductors, chalcopyrites, oxides and halides. The various papers addressed recent experimental and theoretical developments. They covered issues related to crystal growth (bulk and thin films), structure and microstructure, defects, doping, optoelectronic properties and device applications. A theoretical session was dedicated to identifying common themes in the heteroepitaxy and the role of defects in doping, compensation and phase stability of this unique class of materials. Important experimental milestones included the demonstrations of bright blue injection luminescence at room temperatures from junctions based on III-V nitrides and a similar result from multiple quantum wells in a ZnSe double heterojunction at liquid nitrogen temperatures

  7. Growth of two-dimensional Ge crystal by annealing of heteroepitaxial Ag/Ge(111) under N2 ambient

    Science.gov (United States)

    Ito, Koichi; Ohta, Akio; Kurosawa, Masashi; Araidai, Masaaki; Ikeda, Mitsuhisa; Makihara, Katsunori; Miyazaki, Seiichi

    2018-06-01

    The growth of a two-dimensional crystal of Ge atoms on an atomically flat Ag(111) surface has been demonstrated by the thermal annealing of a heteroepitaxial Ag/Ge structure in N2 ambient at atmospheric pressure. The surface morphology and chemical bonding features of heteroepitaxial Ag(111) grown on wet-cleaned Ge(111) after annealing at different temperatures and for various times have been systematically investigated to control the surface segregation of Ge atoms and the planarization of the heteroepitaxial Ag(111) surface.

  8. Semiconductor Manufacturing equipment introduction

    International Nuclear Information System (INIS)

    Im, Jong Sun

    2001-02-01

    This book deals with semiconductor manufacturing equipment. It is comprised of nine chapters, which are manufacturing process of semiconductor device, history of semiconductor manufacturing equipment, kinds and role of semiconductor manufacturing equipment, construction and method of semiconductor manufacturing equipment, introduction of various semiconductor manufacturing equipment, spots of semiconductor manufacturing, technical elements of semiconductor manufacturing equipment, road map of technology of semiconductor manufacturing equipment and semiconductor manufacturing equipment in the 21st century.

  9. 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.

  10. InGaAs Quantum Dots on Cross-Hatch Patterns as a Host for Diluted Magnetic Semiconductor Medium

    Directory of Open Access Journals (Sweden)

    Teeravat Limwongse

    2013-01-01

    Full Text Available Storage density on magnetic medium is increasing at an exponential rate. The magnetic region that stores one bit of information is correspondingly decreasing in size and will ultimately reach quantum dimensions. Magnetic quantum dots (QDs can be grown using semiconductor as a host and magnetic constituents added to give them magnetic properties. Our results show how molecular beam epitaxy and, particularly, lattice-mismatched heteroepitaxy can be used to form laterally aligned, high-density semiconducting host in a single growth run without any use of lithography or etching. Representative results of how semiconductor QD hosts arrange themselves on various stripes and cross-hatch patterns are reported.

  11. Semiconductor spintronics

    International Nuclear Information System (INIS)

    Fabian, J.; Abiague, A.M.; Ertler, Ch.; Stano, P.; Zutic, I.

    2007-01-01

    Spintronics refers commonly to phenomena in which the spin of electrons in a solid state environment plays the determining role. In a more narrow sense spintronics is an emerging research field of electronics: spintronics devices are based on a spin control of electronics, or on an electrical and optical control of spin of magnetism. While metal spintronics has already found its niche in the computer industry - giant magnetoresistance systems are used as hard disk read heads - semiconductor spintronics is vet demonstrate its full potential. This review presents selected themes of semiconductor spintronics, introducing important concepts in spin transport, spin transport, spin injection. Silsbee-Johnson spin-charge coupling, and spin-dependent tunneling, as well as spin relaxation and spin dynamics. The most fundamental spin-dependent interaction in nonmagnetic semiconductors is spin-orbit coupling. Depending on the crystal symmetries of the material, as well as on the structural properties of semiconductor based heterostructures, the spin-orbit coupling takes on different functional forms, giving a nice playground of effective spin-orbit Hamiltonians. The effective Hamiltonians for the most relevant classes of materials and heterostructures are derived here from realistic electronic band structure descriptions. Most semiconductor device systems are still theoretical concepts, waiting for experimental demonstrations. A review of selected proposed, and a few demonstrated devices is presented, with detailed description of two important classes: magnetic resonant tunnel structures and bipolar magnetic diodes and transistors. In view of the importance of ferromagnetic semiconductor material, a brief discussion of diluted magnetic semiconductors is included. In most cases the presentation is of tutorial style, introducing the essential theoretical formalism at an accessible level, with case-study-like illustrations of actual experimental results, as well as with brief

  12. Characterization of homoepitaxial and heteroepitaxial ZnO films grown by pulsed laser deposition

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Z.Q. [Japan Atomic Energy Research Institute, 1233 Watanuki, Takasaki, Gunma 370-1292 (Japan)]. E-mail: chenzq@taka.jaeri.go.jp; Yamamoto, S. [Japan Atomic Energy Research Institute, 1233 Watanuki, Takasaki, Gunma 370-1292 (Japan); Kawasuso, A. [Japan Atomic Energy Research Institute, 1233 Watanuki, Takasaki, Gunma 370-1292 (Japan); Xu, Y. [Japan Atomic Energy Research Institute, 1233 Watanuki, Takasaki, Gunma 370-1292 (Japan); Sekiguchi, T. [National Institute for Materials Science, 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047 (Japan)

    2005-05-15

    Homo- and heteroepitaxial ZnO films were grown on ZnO (0001) and Al{sub 2}O{sub 3} (1-bar 1-bar 2-bar -bar 0) substrates by using pulsed laser deposition. The X-ray diffraction and Raman measurements for these films show good correspondence with the bulk ZnO substrate, which confirms successful growth of c-axis oriented ZnO layer. Strong UV emission was also observed in these films, indicating good optical quality. However, the surface roughness differs very much for the homo- and heteroepitaxial film, that is, much less for the homoepitaxial layer. Positron annihilation measurements reveal a higher vacancy concentration in the homoepitaxial layer.

  13. Heteroepitaxial silicon film growth at 600 oC from an Al-Si eutectic melt

    International Nuclear Information System (INIS)

    Chaudhari, P.; Shim, Heejae; Wacaser, Brent A.; Reuter, Mark C.; Murray, Conal; Reuter, Kathleen B.; Jordan-Sweet, Jean; Ross, Frances M.; Guha, Supratik

    2010-01-01

    A method for growing heteroepitaxial Si films on sapphire was developed using a 6 nm thin Al layer at substrate temperature of 600 o C. Subsequently, the growth of Si nanowires was demonstrated on these films at 490 o C without breaking vacuum. We characterized the properties of the Si films by Raman scattering, X-ray diffraction and transmission electron microscopy and show that the crystal quality and dopant control are promising for photovoltaic applications.

  14. 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

  15. 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

  16. The control of stoichiometry in Epitaxial semiconductor structures. Interfacial Chemistry: Property relations. A workshop review

    Science.gov (United States)

    Bachmann, Klaus J.

    1995-01-01

    A workshop on the control of stoichiometry in epitaxial semiconductor structures was held on August 21-26, 1995 in the hotel Stutenhaus at Vesser in Germany. The secluded location of the workshop in the forest of Thuringia and its informal style stimulated extensive private discussions among the participants and promoted new contacts between young scientists from Eastern and Western Europe and the USA. Topics addressed by the presentations were interactions of precursors to heteroepitaxy and doping with the substrate surface, the control of interfacial properties under the conditions of heteroepitaxy for selected materials systems, methods of characterization of interfaces and native point defects in semiconductor heterostructures and an in depth evaluation of the present status of the control and characterization of the point defect chemistry for one specific semiconductor (ZnGeP2), including studies of both heterostructures and bulk single crystals. The selected examples of presentations and comments given here represent individual choices - made by the author to highlight major points of the discussions.

  17. Semiconductor Detectors

    International Nuclear Information System (INIS)

    Cortina, E.

    2007-01-01

    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)

  18. Low-temperature heteroepitaxial growth of InAlAs layers on ZnSnAs{sub 2}/InP(001)

    Energy Technology Data Exchange (ETDEWEB)

    Oomae, Hiroto; Suzuki, Akiko; Toyota, Hideyuki; Uchitomi, Naotaka [Department of Electrical Engineering, Nagaoka University of Technology, 1603-1 Kamitomioka, Nagaoka 940-2188, Niigata (Japan); Nakamura, Shin' ichi [Center for Instrumental Analysis, College of Science and Engineering, Aoyama Gakuin University, 5-10-1 Fuchinobe, Sagamihara 252-0206, Kanagawa (Japan)

    2015-06-15

    We studied the epitaxial growth of InAlAs on ZnSnAs{sub 2} thin films to establish magnetic heterostructures involving ferromagnetic Mn-doped ZnSnAs{sub 2} (ZnSnAs{sub 2}:Mn) thin films. These heterostructures were successfully grown at temperatures around 300 C to maintain room-temperature ferromagnetism in ZnSnAs{sub 2}:Mn. Reflection high-energy electron diffraction, X-ray diffraction measurements and cross-sectional transmission electron microscopy revealed that the InAlAs layers were pseudomorphically lattice-matched with ZnSnAs{sub 2,} even at the low temperature of 300 C. We attempted to prepare magnetic quantum well structures from the InAlAs/ZnSnAs{sub 2}:Mn magnetic multilayer structure. We found that InAlAs layers heteroepitaxially grown on ZnSnAs{sub 2} and ferromagnetic ZnSnAs{sub 2}:Mn films are suitable for preparing InP-based magnetic semiconductor quantum structures. (copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  19. Semiconductor sensors

    International Nuclear Information System (INIS)

    Hartmann, Frank

    2011-01-01

    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.

  20. 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 ...

  1. Semiconductor annealing

    International Nuclear Information System (INIS)

    Young, J.M.; Scovell, P.D.

    1982-01-01

    A process for annealing crystal damage in ion implanted semiconductor devices in which the device is rapidly heated to a temperature between 450 and 900 0 C and allowed to cool. It has been found that such heating of the device to these relatively low temperatures results in rapid annealing. In one application the device may be heated on a graphite element mounted between electrodes in an inert atmosphere in a chamber. (author)

  2. Effect of Ge nanocluster assembly self-organization at pulsed irradiation by low-energy ions during heteroepitaxy on Si

    CERN Document Server

    Dvurechenskij, A V; Smagina, Z V

    2001-01-01

    Using the method of scanning microscopy one studied experimentally size distribution of Ge clusters formed in course of experiments of two types at Ge heteroepitaxy on Si(111): regular process of molecular-beam epitaxy (MBE); pulse irradiation by approx = 200 eV energy Ge ions. The experiments were conducted at 350 deg C temperature. Pulse irradiation by an ion beam during heteroepitaxy was detected to result in reduction of the average size of Ge clusters, in compacting of their density and in reduction of mean square deviation from the average value in contrast to similar values in experiments devoted to regular MBE

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

    Science.gov (United States)

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

    1993-01-01

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

  4. Effects of Plasma Hydrogenation on Trapping Properties of Dislocations in Heteroepitaxial InP/GaAs

    Science.gov (United States)

    Ringel, S. A.; Chatterjee, B.

    1994-01-01

    In previous work, we have demonstrated the effectiveness of a post-growth hydrogen plasma treatment for passivating the electrical activity of dislocations in metalorganic chemical vapor deposition (MOCVD) grown InP on GaAs substrates by a more than two order of magnitude reduction in deep level concentration and an improvement in reverse bias leakage current by a factor of approx. 20. These results make plasma hydrogenation an extremely promising technique for achieving high efficiency large area and light weight heteroepitaxial InP solar cells for space applications. In this work we investigate the carrier trapping process by dislocations in heteroepitaxial InP/GaAs and the role of hydrogen passivation on this process. It is shown that the charge trapping kinetics of dislocations after hydrogen passivation are significantly altered, approaching point defect-like behavior consistent with a transformation from a high concentration of dislocation-related defect bands within the InP bandgap to a low concentration of individual deep levels after hydrogen passivation. It is further shown that the "apparent" activation energies of dislocation related deep levels, before and after passivation, reduce by approx. 70 meV as DLTS fill pulse times are increased from 1 usec. to 1 msec. A model is proposed which explains these effects based on a reduction of Coulombic interaction between individual core sites along the dislocation cores by hydrogen incorporation. Knowledge of the trapping properties in these specific structures is important to develop optimum, low loss heteroepitaxial InP cells.

  5. In situ boron doping during heteroepitaxial growth of diamond on Ir/YSZ/Si

    Energy Technology Data Exchange (ETDEWEB)

    Sartori, Andre F.; Fischer, Martin; Gsell, Stefan; Schreck, Matthias [Universitaet Augsburg, Institut fuer Physik, 86135 Augsburg (Germany)

    2012-09-15

    In situ boron doping of heteroepitaxial diamond films grown by microwave plasma chemical vapor deposition on Ir/YSZ/Si (001) is investigated. The study comprises the analysis of the gas phase by optical emission spectroscopy (OES) and measurements of B doped films by secondary ion mass spectroscopy (SIMS), cathodoluminescence (CL), and X-ray diffraction (XRD). The OE intensity of BH species scales linearly with the concentration of the boron precursor trimethylboron (TMB) in the feed gas. Addition of CO{sub 2} as an oxygen source causes a proportional reduction of the BH signal. At a ratio C:O = 1, a reduction factor of {proportional_to}50 is obtained. It is shown for two diamond samples that the boron incorporation drops nearly identical to the BH emission intensity. We conclude that the influence of oxygen on boron incorporation is a pure gas phase effect. In contrast, CN and BH emission indicate a negligible interaction between N{sub 2} and TMB added to the feed gas. At the same time, preliminary growth rate measurements show that the boron background pressure in the chamber after growth with TMB completely cancels the growth acceleration by nitrogen up to N{sub 2} concentrations of 100 ppm which points to the dominance of surface processes. Heteroepitaxial diamond films grown on Ir at 50 mbar between 720 and 900 C contain high intrinsic stress that varies from -2.2 GPa compressive at the lowest to slightly tensile at the highest deposition temperature. The observed behavior is similar to former work at 200 mbar in which effective climb of dislocations was suggested as responsible mechanism. Addition of boron rather enhances the stress formation than causing a relaxation. The B concentration in the heteroepitaxial films is deduced by SIMS, CL, and XRD and correlated with the TMB concentration in the gas phase. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  6. Lattice-parameter-difference measurement of heteroepitaxial structures by means of extremely asymmetrical Bragg diffraction

    International Nuclear Information System (INIS)

    Pietsch, U.; Borchard, W.

    1987-01-01

    The sensitivity of measurements of the lattice-parameter difference in monocrystalline heterostructures can be enhanced by use of an extremely asymmetrical diffraction geometry. If the angle of incidence is somewhat higher than the critical angle for total external reflection, the Bragg peak is shifted from the position calculated by kinematic theory. The amount of shift depends on the angle of incidence as well as on the mass density of the material used. For heteroepitaxial structures both the layer and the substrate peaks are shifted but by different amounts. Therefore it becomes possible to characterize layers of totally lattice-matched structures also. (orig.)

  7. Semiconductor annealing

    International Nuclear Information System (INIS)

    Young, J.M.; Scovell, P.D.

    1981-01-01

    A process for annealing crystal damage in ion implanted semiconductor devices is described in which the device is rapidly heated to a temperature between 450 and 600 0 C and allowed to cool. It has been found that such heating of the device to these relatively low temperatures results in rapid annealing. In one application the device may be heated on a graphite element mounted between electrodes in an inert atmosphere in a chamber. The process may be enhanced by the application of optical radiation from a Xenon lamp. (author)

  8. 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.)

  9. InGaAs/InP heteroepitaxial Schottky barrier diodes for terahertz applications

    Science.gov (United States)

    Bhapkar, Udayan V.; Li, Yongjun; Mattauch, Robert J.

    1992-01-01

    This paper explores the feasibility of planar, sub-harmonically pumped, anti-parallel InGaAs/InP heteroepitaxial Schottky diodes for terahertz applications. We present calculations of the (I-V) characteristics of such diodes using a numerical model that considers tunneling. We also present noise and conversion loss predictions of diode mixers operated at 500 GHz, and obtained from a multi-port mixer analysis, using the I-V characteristics predicted by our model. Our calculations indicate that InGaAs/InP heteroepitaxial Schottky barrier diodes are expected to have an I-V characteristic with an ideality factor comparable to that of GaAs Schottky diodes. However, the reverse saturation current of InGaAs/InP diodes is expected to be much greater than that of GaAs diodes. These predictions are confirmed by experiment. The mixer analyses predict that sub-harmonically pumped anti-parallel InGaAs/InP diode mixers are expected to offer a 2 dB greater conversion loss and a somewhat higher single sideband noise temperature than their GaAs counterparts. More importantly, the InGaAs/InP devices are predicted to require only one-tenth of the local oscillator power required by similar GaAs diodes.

  10. Optimization of hetero-epitaxial growth for the threading dislocation density reduction of germanium epilayers

    Science.gov (United States)

    Chong, Haining; Wang, Zhewei; Chen, Chaonan; Xu, Zemin; Wu, Ke; Wu, Lan; Xu, Bo; Ye, Hui

    2018-04-01

    In order to suppress dislocation generation, we develop a "three-step growth" method to heteroepitaxy low dislocation density germanium (Ge) layers on silicon with the MBE process. The method is composed of 3 growth steps: low temperature (LT) seed layer, LT-HT intermediate layer as well as high temperature (HT) epilayer, successively. Threading dislocation density (TDD) of epitaxial Ge layers is measured as low as 1.4 × 106 cm-2 by optimizing the growth parameters. The results of Raman spectrum showed that the internal strain of heteroepitaxial Ge layers is tensile and homogeneous. During the growth of LT-HT intermediate layer, TDD reduction can be obtained by lowering the temperature ramping rate, and high rate deposition maintains smooth surface morphology in Ge epilayer. A mechanism based on thermodynamics is used to explain the TDD and surface morphological dependence on temperature ramping rate and deposition rate. Furthermore, we demonstrate that the Ge layer obtained can provide an excellent platform for III-V materials integrated on Si.

  11. Heteroepitaxial growth of strained multilayer thin films of high-temperature superconductors

    International Nuclear Information System (INIS)

    Gross, R.; Gupta, A.; Olsson, E.; Segmueller, A.; Koren, G.

    1991-01-01

    Recently, the heteroepitaxial growth of multilayer structures of different copper oxide superconductors has been reported by several groups. In general, two different types of multilayer structures should be distinguished. The first kind of mulitlayer is formed by high-T c materials having the same crystal structure and almost the same lattice constants, as for example ReBa 2 Cu 3 O 7 (Re=rare earth) multilayers with alternating Re-elements. In these multilayers the two different rare earth copper oxides (Y/Dy, Y/Pr) have the same orthorhombic unit cell. Due to the very similar lattice constants, the misfit strain is easily accommodated without the formation of defects. The second kind of multilayer is formed by layers of materials having different crystal structure and lattice parameters. In these multilayers the misfit can be coherently accommodated below a critical modulation thickness as discussed below. This renders possible the heteroepitaxial growth of strained multilayer structures, both of two copper oxides of different crystal structure, as has been demonstrated recently for the system YBa 2 Cu 3 O 7-δ /Nd 1.83 Ce 0.17 CuO x , and of superconducting copper oxides and insulating materials. For multilayers of different copper oxides, a combination of almost all high-Tc materials should be possible, since the presence of the CuO 2 sheets in these materials results in similar lattice constants in their basal planes ('a' and 'b'). (orig./BHO)

  12. Charge-carrier transport and recombination in heteroepitaxial CdTe

    International Nuclear Information System (INIS)

    Kuciauskas, Darius; Farrell, Stuart; Dippo, Pat; Moseley, John; Moutinho, Helio; Li, Jian V.; Allende Motz, A. M.; Kanevce, Ana; Zaunbrecher, Katherine; Gessert, Timothy A.; Levi, Dean H.; Metzger, Wyatt K.; Colegrove, Eric; Sivananthan, S.

    2014-01-01

    We analyze charge-carrier dynamics using time-resolved spectroscopy and varying epitaxial CdTe thickness in undoped heteroepitaxial CdTe/ZnTe/Si. By employing one-photon and nonlinear two-photon excitation, we assess surface, interface, and bulk recombination. Two-photon excitation with a focused laser beam enables characterization of recombination velocity at the buried epilayer/substrate interface, 17.5 μm from the sample surface. Measurements with a focused two-photon excitation beam also indicate a fast diffusion component, from which we estimate an electron mobility of 650 cm 2 (Vs) −1 and diffusion coefficient D of 17 cm 2  s −1 . We find limiting recombination at the epitaxial film surface (surface recombination velocity S surface  = (2.8 ± 0.3) × 10 5  cm s −1 ) and at the heteroepitaxial interface (interface recombination velocity S interface  = (4.8 ± 0.5) × 10 5  cm s −1 ). The results demonstrate that reducing surface and interface recombination velocity is critical for photovoltaic solar cells and electronic devices that employ epitaxial CdTe.

  13. Heteroepitaxial growth of basal plane stacking fault free a-plane GaN

    Energy Technology Data Exchange (ETDEWEB)

    Wieneke, Matthias; Hempel, Thomas; Noltemeyer, Martin; Witte, Hartmut; Dadgar, Armin; Blaesing, Juergen; Christen, Juergen; Krost, Alois [Otto-von-Guericke Universitaet Magdeburg, FNW/IEP, Magdeburg (Germany)

    2010-07-01

    Growth of light emitting quantum-wells based on a-plane GaN is a possibility to reduce or even to avoid polarization correlated luminescence red shift and reduction of radiative recombination efficiency. But until now heteroepitaxially grown a-plane GaN films are characterized by a poor crystalline quality expressed by a high density of basal plane stacking faults (BSF) and partial dislocations. We present Si doped a-plane GaN films grown on r-plane sapphire substrates by metal organic vapor phase epitaxy using high temperature AlGaN nucleation layers. FE-SEM images revealed three dimensionally grown GaN crystallites sized up to tenth micrometer in the basal plane and a few tenth micrometers along the c-axes. Though, the full width at half maxima of the X-ray diffraction {omega}-scans of the in-plane GaN(1 anti 100) and GaN(0002) Bragg reflections exhibited a very high crystal quality. Furthermore, luminescence spectra were dominated by near band gap emission, while there was no separated peak of the basal plane stacking fault. In summary we present heteroepitaxially grown a-plane GaN without an evidence of basal plane stacking faults in X-ray diffraction measurements and luminescence spectra.

  14. Heat Islands

    Science.gov (United States)

    EPA's Heat Island Effect Site provides information on heat islands, their impacts, mitigation strategies, related research, a directory of heat island reduction initiatives in U.S. communities, and EPA's Heat Island Reduction Program.

  15. Island biogeography

    DEFF Research Database (Denmark)

    Whittaker, Robert James; Fernández-Palacios, José María; Matthews, Thomas J.

    2017-01-01

    Islands provide classic model biological systems. We review how growing appreciation of geoenvironmental dynamics of marine islands has led to advances in island biogeographic theory accommodating both evolutionary and ecological phenomena. Recognition of distinct island geodynamics permits gener...

  16. 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...

  17. CCST [Center for Compound Semiconductor Technology] research briefs

    International Nuclear Information System (INIS)

    Zipperian, T.E.; Voelker, E.R.

    1989-12-01

    This paper discusses the following topics: theoretical predictions of valence and conduction band offsets in III-V semiconductors; reflectance modulation of a semiconductor superlattice optical mirror; magnetoquantum oscillations of the phonon-drag thermoelectric power in quantum wells; correlation between photoluminescence line shape and device performance of p-channel strained-layer materials; control of threading dislocations in heteroepitaxial structures; improved growth of CdTe on GaAs by patterning; role of structure threading dislocations in relaxation of highly strained single-quantum-well structures; InAlAs growth optimization using reflection mass spectrometry; nonvolatile charge storage in III-V heterostructures; optically triggered thyristor switches; InAsSb strained-layer superlattice infrared detectors with high detectivities; resonant periodic gain surface-emitting semiconductor lasers; performance advantages of strained-quantum-well lasers in AlGaAs/InGaAs; optical integrated circuit for phased-array radar antenna control; and deposition and novel device fabrication from Tl 2 Ca 2 Ba 2 Cu 3 O y thin films

  18. Wafer bowing control of free-standing heteroepitaxial diamond (100) films grown on Ir(100) substrates via patterned nucleation growth

    International Nuclear Information System (INIS)

    Yoshikawa, Taro; Kodama, Hideyuki; Kono, Shozo; Suzuki, Kazuhiro; Sawabe, Atsuhito

    2015-01-01

    The potential of patterned nucleation growth (PNG) technique to control the wafer bowing of free-standing heteroepitaxial diamond films was investigated. The heteroepitaxial diamond (100) films were grown on an Ir(100) substrate via PNG technique with different patterns of nucleation regions (NRs), which were dot-arrays with 8 or 13 μm pitch aligned to < 100 > or < 110 > direction of the Ir(100) substrate. The wafer bows and the local stress distributions of the free-standing films were measured using a confocal micro-Raman spectrometer. For each NR pattern, the stress evolutions within the early stage of diamond growth were also studied together with a scanning electron microscopic observation of the coalescing diamond particles. These investigations revealed that the NR pattern, in terms of pitch and direction of dot-array, strongly affects the compressive stress on the nucleation side of the diamond film and dominantly contributes to the elastic deformation of the free-standing film. This indicates that the PNG technique with an appropriate NR pattern is a promising solution to fabricate free-standing heteroepitaxial diamond films with extremely small bows. - Highlights: • Wafer bowing control of free-standing heteroepitaxial diamond (100) films • Effect of patterned nucleation and growth (PNG) technique on wafer bowing reduction • Influence of nucleation region patterns of PNG on wafer bowing • Internal stress analysis of PNG films via confocal micro-Raman spectroscopy

  19. Implementation of ZnO/ZnMgO strained-layer superlattice for ZnO heteroepitaxial growth on sapphire

    Science.gov (United States)

    Petukhov, Vladimir; Bakin, Andrey; Tsiaoussis, Ioannis; Rothman, Johan; Ivanov, Sergey; Stoemenos, John; Waag, Andreas

    2011-05-01

    The main challenge in fabrication of ZnO-based devices is the absence of reliable p-type material. This is mostly caused by insufficient crystalline quality of the material and not well-enough-developed native point defect control of ZnO. At present high-quality ZnO wafers are still expensive and ZnO heteroepitaxial layers on sapphire are the most reasonable alternative to homoepitaxial layers. But it is still necessary to improve the crystalline quality of the heteroepitaxial layers. One of the approaches to reduce defect density in heteroepitaxial layers is to introduce a strained-layer superlattice (SL) that could stop dislocation propagation from the substrate-layer interface. In the present paper we have employed fifteen periods of a highly strained SL structure. The structure was grown on a conventional double buffer layer comprising of high-temperature MgO/low-temperature ZnO on sapphire. The influence of the SLs on the properties of the heteroepitaxial ZnO layers is investigated. Electrical measurements of the structure with SL revealed very high values of the carrier mobility up to 210 cm2/Vs at room temperature. Structural characterization of the obtained samples showed that the dislocation density in the following ZnO layer was not reduced. The high mobility signal appears to come from the SL structure or the SL/ZnO interface.

  20. Nanocavity effects on misfit accommodation in semiconductors

    International Nuclear Information System (INIS)

    Myers, S.M.; Follstaedt, D.M.; Floro, J.A.; Lee, S.R.; Dawson, L.R.; Reno, J.L.

    1997-04-01

    The authors report an experimental and theoretical examination of the interaction of dislocations with microscopic cavities in semiconductors and the consequences for strain relaxation in heteroepitaxial structures. Dislocation-mediated relaxation and control of the resulting defect microstructure is central to the exploitation of such heterostructures in devices, and they demonstrate here that the introduction of nanometer-scale voids provides a means of strongly influencing this microstructural evolution. Methods for nanocavity formation using He ion implantation and annealing were developed for Si, SiGe on Si, GaAs, and InGaAs on GaAs. In detailed microstructural studies of SiGe on Si, cavities in the interfacial zone were shown to bind dislocations strongly. This effect reduced the excursion of dislocations into the nearby matrix, although threads into the SiGe overlayer were not eliminated. Interfacial cavities also increased the rate of stress relaxation by more than an order of magnitude as a result of enhanced nucleation of misfit dislocations. Further, in the presence of such cavities, the development of thickness variations in the overlayer during relaxation was suppressed. A theoretical model was developed to describe semiquantitatively the forces on dislocations arising from the combined influences of cavities, misfit strain, and the external surface. Predictions of this model are in accord with microstructural observations

  1. EDITORIAL: Non-polar and semipolar nitride semiconductors Non-polar and semipolar nitride semiconductors

    Science.gov (United States)

    Han, Jung; Kneissl, Michael

    2012-02-01

    topics including growth and heteroepitaxy, bulk GaN substrates, theory and modelling, optical properties, laser diodes and LEDs as well as transport properties and electronics. Farrell et al review materials and growth issues for high-performance non- and semipolar light-emitting devices, and Scholz provides an overview of heteroepitaxial growth of semipolar GaN. Okada et al review growth mechanisms of non- and semipolar GaN layers on patterned sapphire substrates, and Vennéguès discusses defect reduction methods for heteroepitaxially grown non- and semipolar III-nitride films. Leung et al explain how kinetic Wulff plots can be used to design and control non-polar and semipolar GaN heteroepitaxy, and a contribution by Sawaki et al explores the impurity incorporation in (1-101) GaN grown on Si substrates. In the area of bulk crystal growth Kucharski et al review non- and semipolar GaN substrates by ammonothermal growth, and Chichibu et al discuss the challenges for epitaxial growth of InGaN on free-standing m-plane GaN substrates. Calculation of semipolar orientations for wurtzitic semiconductor heterostructures and their application to nitrides and oxides are reviewed by Bigenwald et al, and Ito et al present an ab initio approach to reconstruction, adsorption, and incorporation on GaN surfaces. Finally, the theoretical description of non-polar and semipolar nitride semiconductor quantum-well structures is presented by Ahn et al. In a discussion of the optical properties, Kisin et al discuss the effect of the quantum well population on the optical characteristics of polar, semipolar and non-polar III-nitride light emitters, and Jönen et al investigate the indium incorporation and optical properties of non- and semipolar GaInN QW structures. Wernicke et al explore the emission wavelength of polar, non-polar, and semipolar InGaN quantum wells and the incorporation of indium. In a contribution by Melo et al, the gain in polar and non-polar/semipolar gallium

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

    Science.gov (United States)

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

    1995-01-01

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

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

    Science.gov (United States)

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

    1996-01-01

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

  4. Semiconductor laser shearing interferometer

    International Nuclear Information System (INIS)

    Ming Hai; Li Ming; Chen Nong; Xie Jiaping

    1988-03-01

    The application of semiconductor laser on grating shearing interferometry is studied experimentally in the present paper. The method measuring the coherence of semiconductor laser beam by ion etching double frequency grating is proposed. The experimental result of lens aberration with semiconductor laser shearing interferometer is given. Talbot shearing interferometry of semiconductor laser is also described. (author). 2 refs, 9 figs

  5. Structural and optical characterization of GaN heteroepitaxial films on SiC substrates

    International Nuclear Information System (INIS)

    Morse, M.; Wu, P.; Choi, S.; Kim, T.H.; Brown, A.S.; Losurdo, M.; Bruno, G.

    2006-01-01

    We have estimated the threading dislocation density and type via X-ray diffraction and Williamson-Hall analysis to elicit qualitative information directly related to the electrical and optical quality of GaN epitaxial layers grown by PAMBE on 4H- and 6H-SiC substrates. The substrate surface preparation and buffer choice, specifically: Ga flashing for SiC oxide removal, controlled nitridation of SiC, and use of AlN buffer layers all impact the resultant screw dislocation density, but do not significantly influence the edge dislocation density. We show that modification of the substrate surface strongly affects the screw dislocation density, presumably due to impact on nucleation during the initial stages of heteroepitaxy

  6. Centimetre-scale micropore alignment in oriented polycrystalline metal-organic framework films via heteroepitaxial growth.

    Science.gov (United States)

    Falcaro, Paolo; Okada, Kenji; Hara, Takaaki; Ikigaki, Ken; Tokudome, Yasuaki; Thornton, Aaron W; Hill, Anita J; Williams, Timothy; Doonan, Christian; Takahashi, Masahide

    2017-03-01

    The fabrication of oriented, crystalline films of metal-organic frameworks (MOFs) is a critical step toward their application to advanced technologies such as optics, microelectronics, microfluidics and sensing. However, the direct synthesis of MOF films with controlled crystalline orientation remains a significant challenge. Here we report a one-step approach, carried out under mild conditions, that exploits heteroepitaxial growth for the rapid fabrication of oriented polycrystalline MOF films on the centimetre scale. Our methodology employs crystalline copper hydroxide as a substrate and yields MOF films with oriented pore channels on scales that primarily depend on the dimensions of the substrate. To demonstrate that an anisotropic crystalline morphology can translate to a functional property, we assembled a centimetre-scale MOF film in the presence of a dye and showed that the optical response could be switched 'ON' or 'OFF' by simply rotating the film.

  7. Heteroepitaxial Growth of Vacuum-Evaporated Si-Ge Films on Nano structured Silicon Substrates

    International Nuclear Information System (INIS)

    Ayu Wazira Azhari; Ayu Wazira Azhari; Kamaruzzaman Sopian; Saleem Hussain Zaidi

    2015-01-01

    In this study, a low-cost vacuum-evaporated technique is used in the heteroepitaxial growth of Si-Ge films. Three different surface variations are employed: for example polished Si, Si micro pyramids and Si nano pillars profiles. A simple metal-assisted chemical etching method is used to fabricate the Si nano pillars, with Ag acting as a catalyst. Following deposition, substrates are subjected to post-deposition thermal annealing at 1000 degree Celsius to improve the crystallinity of the Ge layer. Optical and morphological studies of surface area are conducted using field emission scanning electron microscopy (FE-SEM), Energy Dispersive X-ray (EDX), Raman spectroscopy and infrared spectroscopy. From the infrared spectroscopy analysis, the energy bandgap for Si-Ge films is estimated to be around 0.94 eV. This high-quality Si-Ge film is most favourable for optics, optoelectronics and high-efficiency solar cell applications. (author)

  8. Sublattice-specific ordering of ZnO layers during the heteroepitaxial growth at different temperatures

    International Nuclear Information System (INIS)

    Redondo-Cubero, A.; Vinnichenko, M.; Muecklich, A.; Kolitsch, A.; Krause, M.; Munoz, E.; Gago, R.

    2011-01-01

    The effect of the substrate temperature on the sublattice ordering in ZnO layers grown by reactive pulsed magnetron sputtering on sapphire has been investigated by different techniques. The improvement of the crystal quality and heteroepitaxial growth at relatively low temperatures (550 deg. C) is verified by x-ray diffraction, high-resolution transmission electron microscopy, Rutherford backscattering spectrometry in channeling mode (RBS/C), and Raman spectroscopy. Sublattice-resolved analysis by resonant RBS/C and Raman spectroscopy reveals that the progressive transition to the single crystal phase is accomplished in a faster way for Zn- than for O-sublattice. This behavior is attributed to the preferential annealing of defects in the Zn sublattice at low temperatures when compared to those of the O sublattice.

  9. Influence of Si-doping on heteroepitaxially grown a-plane GaN

    Energy Technology Data Exchange (ETDEWEB)

    Wieneke, Matthias; Bastek, Barbara; Noltemeyer, Martin; Hempel, Thomas; Rohrbeck, Antje; Witte, Hartmut; Veit, Peter; Blaesing, Juergen; Dadgar, Armin; Christen, Juergen; Krost, Alois [Otto-von-Guericke-Universitaet Magdeburg, FNW/IEP, Universitaetsplatz 2, 39106 Magdeburg (Germany)

    2011-07-01

    Si-doped a-plane GaN samples with nominal doping levels up to 10{sup 20} cm{sup -3} were grown on r-plane sapphire by metal organic vapor phase epitaxy. Silane flow rates higher than 59 nmol/min lead to three dimensional grown crystallites as revealed by scanning electron microscopy. High resolution X-ray diffraction, photoluminescence and cathodoluminescence suggest considerably reduced defect densities in the large micrometer-sized GaN crystallites. Especially, transmission electron microscopy images verify a very low density of basal plane stacking faults less than 10{sup 4} cm{sup -1} in these crystallites consisting of heteroepitaxially grown a-plane GaN. In our presentation the influence of the Si doping on the basal plane stacking faults will be discussed.

  10. Structural and optical characterization of GaN heteroepitaxial films on SiC substrates

    Energy Technology Data Exchange (ETDEWEB)

    Morse, M. [Department of Electrical and Computer Engineering, Duke University, 128 Hudson Hall, Durham, NC (United States) and Department of Physics, Duke University, 128 Hudson Hall, Durham, NC (United States)]. E-mail: michael.morse@duke.edu; Wu, P. [Department of Electrical and Computer Engineering, Duke University, 128 Hudson Hall, Durham, NC (United States); Department of Physics, Duke University, 128 Hudson Hall, Durham, NC (United States); Choi, S. [Department of Electrical and Computer Engineering, Duke University, 128 Hudson Hall, Durham, NC (United States); Department of Physics, Duke University, 128 Hudson Hall, Durham, NC (United States); Kim, T.H. [Department of Electrical and Computer Engineering, Duke University, 128 Hudson Hall, Durham, NC (United States); Department of Physics, Duke University, 128 Hudson Hall, Durham, NC (United States); Brown, A.S. [Department of Electrical and Computer Engineering, Duke University, 128 Hudson Hall, Durham, NC (United States) and Department of Physics, Duke University, 128 Hudson Hall, Durham, NC (United States)]. E-mail: abrown@ee.duke.edu; Losurdo, M. [Institute of Inorganic Methodologies and of Plasmas, IMIP-CNR, via Orabona, 4-70126 Bari (Italy); Bruno, G. [Institute of Inorganic Methodologies and of Plasmas, IMIP-CNR, via Orabona, 4-70126 Bari (Italy)

    2006-10-31

    We have estimated the threading dislocation density and type via X-ray diffraction and Williamson-Hall analysis to elicit qualitative information directly related to the electrical and optical quality of GaN epitaxial layers grown by PAMBE on 4H- and 6H-SiC substrates. The substrate surface preparation and buffer choice, specifically: Ga flashing for SiC oxide removal, controlled nitridation of SiC, and use of AlN buffer layers all impact the resultant screw dislocation density, but do not significantly influence the edge dislocation density. We show that modification of the substrate surface strongly affects the screw dislocation density, presumably due to impact on nucleation during the initial stages of heteroepitaxy.

  11. Semiconductor nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Marstein Erik Stensrud

    2003-07-01

    This thesis presents a study of two material systems containing semiconductor nanocrystals, namely porous silicon (PSi) films and germanium (Ge) nanocrystals embedded in silicon dioxide (SiO2) films. The PSi films were made by anodic etching of silicon (Si) substrates in an electrolyte containing hydrofluoric acid. The PSi films were doped with erbium (Er) using two different doping methods. electrochemical doping and doping by immersing the PSi films in a solution containing Er. The resulting Er concentration profiles were investigated using scanning electron microscopy (SEN1) combined with energy dispersive X-ray analysis (EDS). The main subject of the work on PSi presented in this thesis was investigating and comparing these two doping methods. Ge nanocrystals were made by implanting Ge ions into Si02 films that were subsequently annealed. However. nanocrystal formation occurred only for certain sets of processing parameters. The dependence of the microstructure of the Ge implanted Si02 films on the processing parameters were therefore investigated. A range of methods were employed for these investigations, including transmission electron microscopy (TEM) combined with EDS, X-ray photoelectron spectroscopy (XPS) and secondary ion mass spectroscopy (SIMS). The observed structures, ranging from Ge nanocrystals to voids with diameters of several tens of nanometers and Ge rich Si02 films without any nanocrystals is described. A model explaining the void formation is also presented. For certain sets of processing parameters. An accumulation of Ge at the Si-Si02 interface was observed. The effect of this accumulation on the electrical properties of MOS structures made from Ge implanted SiO2 films was investigated using CV-measurements. (Author)

  12. 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.

  13. Understanding the elastic relaxation mechanisms of strain in Ge islands on pit-patterned Si(001) substrates

    International Nuclear Information System (INIS)

    Vastola, G; Montalenti, F; Miglio, Leo

    2008-01-01

    Substrate pre-patterning is a new and effective route for growing ordered arrays of heteroepitaxial nanoislands. Here, by exploiting elasticity theory solved by using finite element methods, we show why islands growing inside pits are better relaxed with respect to the flat-substrate case. Pit pre-patterning is demonstrated to be more important than previously realized, allowing for further degrees of freedom in controlling not only positioning but also shape, strain, and coherence of the growing islands. Our results offer a solid interpretation for the recent experimental results obtained by the group of Professor Guenther Bauer.

  14. Solid spectroscopy: semiconductors

    International Nuclear Information System (INIS)

    Silva, C.E.T.G. da

    1983-01-01

    Photoemission as technique of study of the semiconductor electronic structure is shortly discussed. Homogeneous and heterogeneous semiconductors, where volume and surface electronic structure, core levels and O and H chemisorption in GaAs, Schottky barrier are treated, respectively. Amorphous semiconductors are also discussed. (L.C.) [pt

  15. Canary Islands

    Science.gov (United States)

    1992-01-01

    This easterly looking view shows the seven major volcanic islands of the Canary Island chain (28.0N, 16.5W) and offers a unique view of the islands that have become a frequent vacation spot for Europeans. The northwest coastline of Africa, (Morocco and Western Sahara), is visible in the background. Frequently, these islands create an impact on local weather (cloud formations) and ocean currents (island wakes) as seen in this photo.

  16. Influence of Microstructure on the Electrical Properties of Heteroepitaxial TiN Films

    Science.gov (United States)

    Xiang, Wenfeng; Liu, Yuan; Zhang, Jiaqi

    2018-03-01

    Heteroepitaxial TiN films were deposited on Si substrates by pulse laser deposition at different substrate temperature. The microstructure and surface morphology of the films were investigated by X-ray diffraction (θ-2θ scan, ω-scan, and ϕ-scan) and atomic force microscopy. The electrical properties of the prepared TiN films were studied using a physical property measurement system. The experimental results showed that the crystallinity and surface morphology of the TiN films were improved gradually with increasing substrate temperature below 700 °C. Specially, single crystal TiN films were prepared when substrate temperature is above 700 °C; However, the quality of TiN films gradually worsened when the substrate temperature was increased further. The electrical properties of the films were directly correlated to their crystalline quality. At the optimal substrate temperature of 700 °C, the TiN films exhibited the lowest resistivity and highest mobility of 25.7 μΩ cm and 36.1 cm2/V s, respectively. In addition, the mechanism concerning the influence of substrate temperature on the microstructure of TiN films is discussed in detail.

  17. Trends in heteroepitaxy of III-Vs on silicon for photonic and photovoltaic applications

    Science.gov (United States)

    Lourdudoss, Sebastian; Junesand, Carl; Kataria, Himanshu; Metaferia, Wondwosen; Omanakuttan, Giriprasanth; Sun, Yan-Ting; Wang, Zhechao; Olsson, Fredrik

    2017-02-01

    We present and compare the existing methods of heteroepitaxy of III-Vs on silicon and their trends. We focus on the epitaxial lateral overgrowth (ELOG) method as a means of achieving good quality III-Vs on silicon. Initially conducted primarily by near-equilibrium epitaxial methods such as liquid phase epitaxy and hydride vapour phase epitaxy, nowadays ELOG is being carried out even by non-equilibrium methods such as metal organic vapour phase epitaxy. In the ELOG method, the intermediate defective seed and the mask layers still exist between the laterally grown purer III-V layer and silicon. In a modified ELOG method called corrugated epitaxial lateral overgrowth (CELOG) method, it is possible to obtain direct interface between the III-V layer and silicon. In this presentation we exemplify some recent results obtained by these techniques. We assess the potentials of these methods along with the other existing methods for realizing truly monolithic photonic integration on silicon and III-V/Si heterojunction solar cells.

  18. Kinetic mechanism of V-shaped twinning in 3C/4H-SiC heteroepitaxy

    Energy Technology Data Exchange (ETDEWEB)

    Xin, Bin; Zhang, Yu-Ming; Jia, Ren-Xu, E-mail: rxjia@mail.xidian.edu.cn [School of Microelectronics, Xidian University, Key Laboratory of Wide Band-Gap Semiconductor Materials and Devices, Xi' an 710071 (China); Wu, Hong-Ming [Graduate Institute of Electronics Engineering, National Taiwan University, 10617 Taipei, Taiwan (China); Feng, Zhe Chuan [Graduate Institute of Photonics and Optoelectronics, National Taiwan University, 10617 Taipei, Taiwan and Laboratory of Optoelectronic Materials and Detection Technology, Guangxi Key Laboratory for the Relativistic Astrophysics, College of Physics Science and Technology, Guangxi University, Nanning 530004 (China); Lin, Hao-Hsiung [Graduate Institute of Electronics Engineering, National Taiwan University, 10617 Taipei, Taiwan and Graduate Institute of Photonics and Optoelectronics, National Taiwan University, 10617 Taipei, Taiwan (China)

    2016-05-15

    The authors investigated the kinetic mechanism of V-shaped twinning in 3C/4H-SiC heteroepitaxy. A fourfold V-shaped twinning complex was found, and its interface was measured with high-resolution transmission electron microscopy (HRTEM). Two linear coherent boundaries and a nonlinear incoherent boundary (also called the double-position boundary) were observed. On the basis of the HRTEM results, the authors proposed an adatom migration growth model, in which the activation barrier at the coherent boundary is much lower than that at the incoherent boundary. From a kinetic perspective, adatoms are prone to migrate to the side of the boundary with the lower potential energy if they have sufficient thermal energy to overcome the activation barrier. In the case of a coherent boundary, the growth rates of the domains either side of the boundary can be balanced through the intermigration of adatoms, leading to a linear boundary. Conversely, it is difficult for adatoms to migrate across an incoherent boundary, which results in asynchronous growth rates and a nonlinear boundary.

  19. Compound Semiconductor Radiation Detector

    International Nuclear Information System (INIS)

    Kim, Y. K.; Park, S. H.; Lee, W. G.; Ha, J. H.

    2005-01-01

    In 1945, Van Heerden measured α, β and γ radiations with the cooled AgCl crystal. It was the first radiation measurement using the compound semiconductor detector. Since then the compound semiconductor has been extensively studied as radiation detector. Generally the radiation detector can be divided into the gas detector, the scintillator and the semiconductor detector. The semiconductor detector has good points comparing to other radiation detectors. Since the density of the semiconductor detector is higher than that of the gas detector, the semiconductor detector can be made with the compact size to measure the high energy radiation. In the scintillator, the radiation is measured with the two-step process. That is, the radiation is converted into the photons, which are changed into electrons by a photo-detector, inside the scintillator. However in the semiconductor radiation detector, the radiation is measured only with the one-step process. The electron-hole pairs are generated from the radiation interaction inside the semiconductor detector, and these electrons and charged ions are directly collected to get the signal. The energy resolution of the semiconductor detector is generally better than that of the scintillator. At present, the commonly used semiconductors as the radiation detector are Si and Ge. However, these semiconductor detectors have weak points. That is, one needs thick material to measure the high energy radiation because of the relatively low atomic number of the composite material. In Ge case, the dark current of the detector is large at room temperature because of the small band-gap energy. Recently the compound semiconductor detectors have been extensively studied to overcome these problems. In this paper, we will briefly summarize the recent research topics about the compound semiconductor detector. We will introduce the research activities of our group, too

  20. Semiconductor apparatus and method of fabrication for a semiconductor apparatus

    NARCIS (Netherlands)

    2010-01-01

    The invention relates to a semiconductor apparatus (1) and a method of fabrication for a semiconductor apparatus (1), wherein the semiconductor apparatus (1) comprises a semiconductor layer (2) and a passivation layer (3), arranged on a surface of the semiconductor layer (2), for passivating the

  1. 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...

  2. Contacts to semiconductors

    International Nuclear Information System (INIS)

    Tove, P.A.

    1975-08-01

    Contacts to semiconductors play an important role in most semiconductor devices. These devices range from microelectronics to power components, from high-sensitivity light or radiation detectors to light-emitting of microwave-generating components. Silicon is the dominating material but compound semiconductors are increasing in importance. The following survey is an attempt to classify contact properties and the physical mechanisms involved, as well as fabrication methods and methods of investigation. The main interest is in metal-semiconductor type contacts where a few basic concepts are dealt with in some detail. (Auth.)

  3. Semiconductor Electrical Measurements Laboratory

    Data.gov (United States)

    Federal Laboratory Consortium — The Semiconductor Electrical Measurements Laboratory is a research laboratory which complements the Optical Measurements Laboratory. The laboratory provides for Hall...

  4. GaAs FETs and novel heteroepitaxial quaternary lasers grown on InP substrates by organometallic chemical vapor deposition

    International Nuclear Information System (INIS)

    Lo, Y.H.; Bhat, R.; Chang-Hasnain, C.; Caneau, C.; Zah, C.E.; Lee, T.P.

    1988-01-01

    This paper reports the GaAs MESFETs and 1.3μm buried hetero-structure lasers with AlGaAs/GaAs lateral confinement layers simultaneously grown by OMCVD and fabricated on InP structures. The 1μm recessed gate MESFET has a transconductance of 220 mS/mm and the novel structured laser has a CW threshold current of 45 mA. The heteroepitaxy technology and devices show great promises for long wavelength opto-electronic integrated circuits

  5. Synthesis of silicon carbide coating on diamond by microwave heating of diamond and silicon powder: A heteroepitaxial growth

    Energy Technology Data Exchange (ETDEWEB)

    Leparoux, S. [Empa, Department of Materials Technology, Feuerwerkerstrasse 39, CH-3602 Thun (Switzerland)], E-mail: susanne.leparoux@empa.ch; Diot, C. [Consultant, allee de Mozart 10, F-92300 Chatillon (France); Dubach, A. [Empa, Department of Materials Technology, Feuerwerkerstrasse 39, CH-3602 Thun (Switzerland); Vaucher, S. [Empa, Department of Materials Technology, Feuerwerkerstrasse 39, CH-3602 Thun (Switzerland)

    2007-10-15

    When a powder mixture of diamond and silicon is heated by microwaves, heteroepitaxial growth of SiC is observed on the (1 1 1) as well as on the (1 0 0) faces of the diamond. The SiC over-layer was characterized by X-ray diffraction and scanning electron microscopy. High-resolution scanning electron microscopy shows the presence of triangular silicon carbide on the (1 1 1) faces of diamond while prismatic crystals are found on the (1 0 0) faces. The crystal growth seems to be favored in the plane parallel to the face (1 1 1)

  6. Synthesis of silicon carbide coating on diamond by microwave heating of diamond and silicon powder: A heteroepitaxial growth

    International Nuclear Information System (INIS)

    Leparoux, S.; Diot, C.; Dubach, A.; Vaucher, S.

    2007-01-01

    When a powder mixture of diamond and silicon is heated by microwaves, heteroepitaxial growth of SiC is observed on the (1 1 1) as well as on the (1 0 0) faces of the diamond. The SiC over-layer was characterized by X-ray diffraction and scanning electron microscopy. High-resolution scanning electron microscopy shows the presence of triangular silicon carbide on the (1 1 1) faces of diamond while prismatic crystals are found on the (1 0 0) faces. The crystal growth seems to be favored in the plane parallel to the face (1 1 1)

  7. Bottom-Up Nano-heteroepitaxy of Wafer-Scale Semipolar GaN on (001) Si

    KAUST Repository

    Hus, Jui Wei

    2015-07-15

    Semipolar {101¯1} InGaN quantum wells are grown on (001) Si substrates with an Al-free buffer and wafer-scale uniformity. The novel structure is achieved by a bottom-up nano-heteroepitaxy employing self-organized ZnO nanorods as the strain-relieving layer. This ZnO nanostructure unlocks the problems encountered by the conventional AlN-based buffer, which grows slowly and contaminates the growth chamber. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Electronic properties of semiconductor surfaces and metal/semiconductor interfaces

    Energy Technology Data Exchange (ETDEWEB)

    Tallarida, M.

    2005-05-15

    This thesis reports investigations of the electronic properties of a semiconductor surface (silicon carbide), a reactive metal/semiconductor interface (manganese/silicon) and a non-reactive metal/semiconductor interface (aluminum-magnesium alloy/silicon). The (2 x 1) reconstruction of the 6H-SiC(0001) surface has been obtained by cleaving the sample along the (0001) direction. This reconstruction has not been observed up to now for this compound, and has been compared with those of similar elemental semiconductors of the fourth group of the periodic table. This comparison has been carried out by making use of photoemission spectroscopy, analyzing the core level shifts of both Si 2p and C 1s core levels in terms of charge transfer between atoms of both elements and in different chemical environments. From this comparison, a difference between the reconstruction on the Si-terminated and the C-terminated surface was established, due to the ionic nature of the Si-C bond. The growth of manganese films on Si(111) in the 1-5 ML thickness range has been studied by means of LEED, STM and photoemission spectroscopy. By the complementary use of these surface science techniques, two different phases have been observed for two thickness regimes (<1 ML and >1 ML), which exhibit a different electronic character. The two reconstructions, the (1 x 1)-phase and the ({radical}3 x {radical}3)R30 -phase, are due to silicide formation, as observed in core level spectroscopy. The growth proceeds via island formation in the monolayer regime, while the thicker films show flat layers interrupted by deep holes. On the basis of STM investigations, this growth mode has been attributed to strain due to lattice mismatch between the substrate and the silicide. Co-deposition of Al and Mg onto a Si(111) substrate at low temperature (100K) resulted in the formation of thin alloy films. By varying the relative content of both elements, the thin films exhibited different electronic properties

  9. Growth, stress, and defects of heteroepitaxial diamond on Ir/YSZ/Si(111)

    Science.gov (United States)

    Gallheber, B.-C.; Fischer, M.; Mayr, M.; Straub, J.; Schreck, M.

    2018-06-01

    Basic understanding of the fundamental processes in crystal growth as well as the structural quality of diamond synthesized by chemical vapour deposition on iridium surfaces has reached a high level for samples with (001) orientation. Diamond deposition on the alternative (111) surface is generally more challenging but of appreciable technological interest, too. In the present work, heteroepitaxy of diamond on Ir/YSZ/Si(111) with different off-axis angles and directions has been studied. During the growth of the first microns, strong and complex intrinsic stress states were rapidly formed. They restricted the range of suitable temperatures in this study to values between 830 °C and 970 °C. At low-stress conditions, the maximum growth rates were about 1 μm/h. They facilitated long-time processes which yielded pronounced structural improvements with minimum values of 0.08° for the azimuthal mosaic spread, 4 × 107 cm-2 for the dislocation density and 1.8 cm-1 for the Raman line width. This refinement is even faster than on (001) growth surfaces. It indicates substantial differences between the two crystal directions in terms of merging of mosaic blocks and annihilation of dislocations. Crystals with a thickness of up to 330 μm have been grown. The correlation of photoluminescence and μ-Raman tomograms with topography data also revealed fundamental differences in the off-axis growth between (001) and (111) orientation. Finally, the analysis of the microscopic structures at the growth surface provided the base for a model that can conclusively explain the intriguing reversal of stress tensor anisotropy caused by a simple inversion in sign of the off-axis angle.

  10. Semiconductors data handbook

    CERN Document Server

    Madelung, Otfried

    2004-01-01

    This volume Semiconductors: Data Handbook contains frequently used data from the corresponding larger Landolt-Börnstein handbooks in a low price book for the individual scientist working in the laboratory. The Handbook contain important information about a large number of semiconductors

  11. Semiconductor radiation detection systems

    CERN Document Server

    2010-01-01

    Covers research in semiconductor detector and integrated circuit design in the context of medical imaging using ionizing radiation. This book explores other applications of semiconductor radiation detection systems in security applications such as luggage scanning, dirty bomb detection and border control.

  12. Spin physics in semiconductors

    CERN Document Server

    Dyakonov, Mikhail I

    2008-01-01

    This book describes beautiful optical and transport phenomena related to the electron and nuclear spins in semiconductors with emphasis on a clear presentation of the physics involved. Recent results on quantum wells and quantum dots are reviewed. The book is intended for students and researchers in the fields of semiconductor physics and nanoelectronics.

  13. 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...

  14. Terahertz semiconductor nonlinear optics

    DEFF Research Database (Denmark)

    Turchinovich, Dmitry; Hvam, Jørn Märcher; Hoffmann, Matthias

    2013-01-01

    In this proceedings we describe our recent results on semiconductor nonlinear optics, investigated using single-cycle THz pulses. We demonstrate the nonlinear absorption and self-phase modulation of strong-field THz pulses in doped semiconductors, using n-GaAs as a model system. The THz...... nonlinearity in doped semiconductors originates from the near-instantaneous heating of free electrons in the ponderomotive potential created by electric field of the THz pulse, leading to ultrafast increase of electron effective mass by intervalley scattering. Modification of effective mass in turn leads...... to a decrease of plasma frequency in semiconductor and produces a substantial modification of THz-range material dielectric function, described by the Drude model. As a result, the nonlinearity of both absorption coefficient and refractive index of the semiconductor is observed. In particular we demonstrate...

  15. Organic semiconductor crystals.

    Science.gov (United States)

    Wang, Chengliang; Dong, Huanli; Jiang, Lang; Hu, Wenping

    2018-01-22

    Organic semiconductors have attracted a lot of attention since the discovery of highly doped conductive polymers, due to the potential application in field-effect transistors (OFETs), light-emitting diodes (OLEDs) and photovoltaic cells (OPVs). Single crystals of organic semiconductors are particularly intriguing because they are free of grain boundaries and have long-range periodic order as well as minimal traps and defects. Hence, organic semiconductor crystals provide a powerful tool for revealing the intrinsic properties, examining the structure-property relationships, demonstrating the important factors for high performance devices and uncovering fundamental physics in organic semiconductors. This review provides a comprehensive overview of the molecular packing, morphology and charge transport features of organic semiconductor crystals, the control of crystallization for achieving high quality crystals and the device physics in the three main applications. We hope that this comprehensive summary can give a clear picture of the state-of-art status and guide future work in this area.

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

    Science.gov (United States)

    Ringel, S. A.; Chatterjee, B.

    2004-01-01

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

  17. Heteroepitaxial growth of CuInS2 thin films on sapphire by radio frequency reactive sputtering

    International Nuclear Information System (INIS)

    He, Y.B.; Kriegseis, W.; Meyer, B.K.; Polity, A.; Serafin, M.

    2003-01-01

    Direct heteroepitaxial growth of uniform stoichiometric CuInS 2 (CIS) thin films on sapphire (0001) substrates has been achieved by radio frequency reactive sputtering. X-ray ω-2θ scans reveal that the sputtered layers grow in a (112) orientation with a chalcopyrite structure. A rocking curve full width at half maximum of about 0.05 deg. (180 arc sec) for the (112) peak demonstrates a nearly perfect out-of-plane arrangement of CIS (112) parallel sapphire (0001). X-ray diffraction Phi scans further illustrate an excellent in-plane ordering of CIS [1-bar10] parallel sapphire (101-bar0). The sputtered thin CIS epilayers had a smooth surface with a typical root-mean-square roughness of about 3.3 nm as evaluated by atomic force microscopy. The epitaxial growth of tetragonal CIS on hexagonal sapphire provides evidence that heteroepitaxial growth may be realized between structures of different symmetry, such as films of cubic or tetragonal structures on hexagonal substrates or vice versa

  18. Heteroepitaxy of zinc-blende SiC nano-dots on Si substrate by organometallic ion beam

    International Nuclear Information System (INIS)

    Matsumoto, T.; Kiuchi, M.; Sugimoto, S.; Goto, S.

    2006-01-01

    The self-assembled SiC nano-dots were fabricated on Si(111) substrate at low-temperatures using the organometallic ion beam deposition technique. The single precursor of methylsilicenium ions (SiCH 3 + ) with the energy of 100 eV was deposited on Si(111) substrate at 500, 550 and 600 deg. C. The characteristics of the self-assembled SiC nano-dots were analyzed by reflection high-energy electron diffraction (RHEED), Raman spectroscopy and atomic force microscope (AFM). The RHEED patterns showed that the crystal structure of the SiC nano-dots formed on Si(111) substrate was zinc-blende SiC (3C-SiC) and it was heteroepitaxy. The self-assembled SiC nano-dots were like a dome in shape, and their sizes were the length of 200-300 nm and the height of 10-15 nm. Despite the low-temperature of 500 deg. C as SiC crystallization the heteroepitaxial SiC nano-dots were fabricated on Si(111) substrate using the organometallic ion beam

  19. Kinetic Monte Carlo simulations and cross-sectional scanning tunneling microscopy as tools to investigate the heteroepitaxial capping of self-assembled quantum dots

    NARCIS (Netherlands)

    Keizer, J.G.; Koenraad, P.M.; Smereka, P.; Ulloa, J.M.; Guzman, A.; Hierro, A.

    2012-01-01

    In the last decade, an ever increasing understanding of heteroepitaxial growth has paved the way for the fabrication of a multitude of self-assembled nanostructures. Nowadays, nanostructures such as quantum rings,1 quantum wires,2 quantum dashes,3 quantum rods,4 and quantum dots (QDs)5 can be grown

  20. Analysis and evaluation for practical application of photovoltaic power generation system. Analysis and evaluation for development of extra-high efficiency solar cells (fundamental research on extra-high efficiency III-V compound semiconductor tandem solar cells); Taiyoko hatsuden system jitsuyoka no tame no kaiseki hyoka. Chokokoritsu taiyo denchi no gijutsu kaihatsu no tame no kaiseki hyoka (chokokoritsu III-V zoku kagobutsu taiyo denchi gijutsu kaihatsu)

    Energy Technology Data Exchange (ETDEWEB)

    Sekikawa, T; Kawanami, H; Sakata, I; Nagai, K; Matsumoto, K; Miki, K [Electrotechnical Laboratory, Tsukuba (Japan)

    1994-12-01

    Described herein are the results of the FY1994 research program for development of extra-high efficiency III-V compound semiconductor tandem solar cells. Heteroepitaxial structures of compound semiconductors, such as GaAs, on silicon substrates are analyzed and evaluated by EXAFS, Raman and RHEED for the initial stage of the film growth and heterointerfaces. The device capable of in-situ observation of the growing surface structures during the period of heteroepitaxial film growth is introduced, to investigate the effects of rise-up and initial growth conditions on defects. The effects of atomic hydrogen on growth of a GaAs film on a silicon substrate are investigated from photoluminescence and solar cell characteristics, to confirm the effects of reducing defects. Heteroepitaxial growth of InGaP, which has the optimum band width for forming multi-junction silicon solar cells, on a silicon substrate is investigated, to find that an interfacial buffer layer is necessary to form a good film. 2 figs.

  1. Defects in semiconductors

    International Nuclear Information System (INIS)

    Pimentel, C.A.F.

    1983-01-01

    Some problems openned in the study of defects in semiconductors are presented. In particular, a review is made of the more important problems in Si monocrystals of basic and technological interest: microdefects and the presence of oxigen and carbon. The techniques usually utilized in the semiconductor material characterization are emphatized according its potentialities. Some applications of x-ray techniques in the epitaxial shell characterization in heterostructures, importants in electronic optics, are shown. The increase in the efficiency of these defect analysis methods in semiconductor materials with the use of synchrotron x-ray sources is shown. (L.C.) [pt

  2. Introduction to Semiconductor Devices

    Science.gov (United States)

    Brennan, Kevin F.

    2005-03-01

    This volume offers a solid foundation for understanding the most important devices used in the hottest areas of electronic engineering today, from semiconductor fundamentals to state-of-the-art semiconductor devices in the telecommunications and computing industries. Kevin Brennan describes future approaches to computing hardware and RF power amplifiers, and explains how emerging trends and system demands of computing and telecommunications systems influence the choice, design and operation of semiconductor devices. In addition, he covers MODFETs and MOSFETs, short channel effects, and the challenges faced by continuing miniaturization. His book is both an excellent senior/graduate text and a valuable reference for practicing engineers and researchers.

  3. Spin physics in semiconductors

    CERN Document Server

    2017-01-01

    This book offers an extensive introduction to the extremely rich and intriguing field of spin-related phenomena in semiconductors. In this second edition, all chapters have been updated to include the latest experimental and theoretical research. Furthermore, it covers the entire field: bulk semiconductors, two-dimensional semiconductor structures, quantum dots, optical and electric effects, spin-related effects, electron-nuclei spin interactions, Spin Hall effect, spin torques, etc. Thanks to its self-contained style, the book is ideally suited for graduate students and researchers new to the field.

  4. Physics of semiconductor lasers

    CERN Document Server

    Mroziewicz, B; Nakwaski, W

    2013-01-01

    Written for readers who have some background in solid state physics but do not necessarily possess any knowledge of semiconductor lasers, this book provides a comprehensive and concise account of fundamental semiconductor laser physics, technology and properties. The principles of operation of these lasers are therefore discussed in detail with the interrelations between their design and optical, electrical and thermal properties. The relative merits of a large number of laser structures and their parameters are described to acquaint the reader with the various aspects of the semiconductor l

  5. 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.

  6. 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

  7. Biggest semiconductor installed

    CERN Multimedia

    2008-01-01

    Scientists and technicians at the European Laboratory for Particle Physics, commonly known by its French acronym CERN (Centre Europen pour la Recherche Nuclaire), have completed the installation of the largest semiconductor silicon detector.

  8. Compact semiconductor lasers

    CERN Document Server

    Yu, Siyuan; Lourtioz, Jean-Michel

    2014-01-01

    This book brings together in a single volume a unique contribution by the top experts around the world in the field of compact semiconductor lasers to provide a comprehensive description and analysis of the current status as well as future directions in the field of micro- and nano-scale semiconductor lasers. It is organized according to the various forms of micro- or nano-laser cavity configurations with each chapter discussing key technical issues, including semiconductor carrier recombination processes and optical gain dynamics, photonic confinement behavior and output coupling mechanisms, carrier transport considerations relevant to the injection process, and emission mode control. Required reading for those working in and researching the area of semiconductors lasers and micro-electronics.

  9. Marshall Islands

    OpenAIRE

    World Bank

    2015-01-01

    This note aims to build understanding of the existing disaster risk financing and insurance (DRFI) tools in use in The Marshall Islands and to identify gaps where potential engagement could further develop financial resilience. The likelihood that a hazardous event will have a significant impact on the Marshall Islands has risen with the increasing levels of population and assets in the urban ...

  10. 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

  11. Market survey of semiconductors

    International Nuclear Information System (INIS)

    Mackintosh, I.M.; Diegel, D.; Brown, A.; Brinker, C.S. den

    1977-06-01

    Examination of technology and product trends over the range of current and future products in integrated circuits and optoelectronic displays. Analysis and forecast of major economic influences that affect the production costs of integrated circuits and optoelectronic displays. Forecast of the applications and markets for integrated circuits up to 1985 in West Europe, the USA and Japan. Historic development of the semiconductor industry and the prevailing tendencies - factors which influence success in the semiconductor industry. (orig.) [de

  12. Electronic properties of semiconductor heterostructures

    International Nuclear Information System (INIS)

    Einevoll, G.T.

    1991-02-01

    Ten papers on the electronic properties of semiconductors and semiconductor heterostructures constitute the backbone of this thesis. Four papers address the form and validity of the single-band effective mass approximation for semiconductor heterostructures. In four other papers properties of acceptor states in bulk semiconductors and semiconductor heterostructures are studied using the novel effective bond-orbital model. The last two papers deal with localized excitions. 122 refs

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

    Science.gov (United States)

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

    1995-01-01

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

  14. The effect of Ge precursor on the heteroepitaxy of Ge1-x Sn x epilayers on a Si (001) substrate

    Science.gov (United States)

    Jahandar, Pedram; Weisshaupt, David; Colston, Gerard; Allred, Phil; Schulze, Jorg; Myronov, Maksym

    2018-03-01

    The heteroepitaxial growth of Ge1-x Sn x on a Si (001) substrate, via a relaxed Ge buffer, has been studied using two commonly available commercial Ge precursors, Germane (GeH4) and Digermane (Ge2H6), by means of chemical vapour deposition at reduced pressures (RP-CVD). Both precursors demonstrate growth of strained and relaxed Ge1-x Sn x epilayers, however Sn incorporation is significantly higher when using the more reactive Ge2H6 precursor. As Ge2H6 is significantly more expensive, difficult to handle or store than GeH4, developing high Sn content epilayers using the latter precursor is of great interest. This study demonstrates the key differences between the two precursors and offers routes to process optimisation which will enable high Sn content alloys at relatively low cost.

  15. Dislocation reduction in heteroepitaxial Ge on Si using SiO{sub 2} lined etch pits and epitaxial lateral overgrowth

    Energy Technology Data Exchange (ETDEWEB)

    Leonhardt, Darin; Han, Sang M. [Department of Chemical and Nuclear Engineering, University of New Mexico, Albuquerque, New Mexico 87131 (United States)

    2011-09-12

    We report a technique that significantly reduces threading dislocations in Ge on Si heteroepitaxy. Germanium is first grown on Si and etched to produce pits in the surface where threading dislocations terminate. Further processing leaves a layer of SiO{sub 2} only within etch pits. Subsequent selective epitaxial Ge growth results in coalescence above the SiO{sub 2}. The SiO{sub 2} blocks the threading dislocations from propagating into the upper Ge epilayer. With annealed Ge films grown on Si, the said method reduces the defect density from 2.6 x 10{sup 8} to 1.7 x 10{sup 6} cm{sup -2}, potentially making the layer suitable for electronic and photovoltaic devices.

  16. Analysis of the Si(111) surface prepared in chemical vapor ambient for subsequent III-V heteroepitaxy

    International Nuclear Information System (INIS)

    Zhao, W.; Steidl, M.; Paszuk, A.; Brückner, S.; Dobrich, A.; Supplie, O.; Kleinschmidt, P.; Hannappel, T.

    2017-01-01

    Highlights: • We investigate the Si(111) surface prepared in CVD ambient at 1000 °C in 950 mbar H_2. • UHV-based XPS, LEED, STM and FTIR as well as ambient AFM are applied. • After processing the Si(111) surface is free of contamination and atomically flat. • The surface exhibits a (1 × 1) reconstruction and monohydride termination. • Wet-chemical pretreatment and homoepitaxy are required for a regular step structure. - Abstract: For well-defined heteroepitaxial growth of III-V epilayers on Si(111) substrates the atomic structure of the silicon surface is an essential element. Here, we study the preparation of the Si(111) surface in H_2-based chemical vapor ambient as well as its atomic structure after contamination-free transfer to ultrahigh vacuum (UHV). Applying complementary UHV-based techniques, we derive a complete picture of the atomic surface structure and its chemical composition. X-ray photoelectron spectroscopy measurements after high-temperature annealing confirm a Si surface free of any traces of oxygen or other impurities. The annealing in H_2 ambient leads to a monohydride surface termination, as verified by Fourier-transform infrared spectroscopy. Scanning tunneling microscopy confirms a well ordered, atomically smooth surface, which is (1 × 1) reconstructed, in agreement with low energy electron diffraction patterns. Atomic force microscopy reveals a significant influence of homoepitaxy and wet-chemical pretreatment on the surface morphology. Our findings show that wet-chemical pretreatment followed by high-temperature annealing leads to contamination-free, atomically flat Si(111) surfaces, which are ideally suited for subsequent III-V heteroepitaxy.

  17. Analysis of the Si(111) surface prepared in chemical vapor ambient for subsequent III-V heteroepitaxy

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, W.; Steidl, M.; Paszuk, A. [Technische Universität Ilmenau, Institut für Physik, 98693 Ilmenau (Germany); Brückner, S. [Technische Universität Ilmenau, Institut für Physik, 98693 Ilmenau (Germany); Helmholtz-Zentrum Berlin, Institut für Solare Brennstoffe, 14109 Berlin (Germany); Dobrich, A. [Technische Universität Ilmenau, Institut für Physik, 98693 Ilmenau (Germany); Supplie, O. [Technische Universität Ilmenau, Institut für Physik, 98693 Ilmenau (Germany); Helmholtz-Zentrum Berlin, Institut für Solare Brennstoffe, 14109 Berlin (Germany); Kleinschmidt, P. [Technische Universität Ilmenau, Institut für Physik, 98693 Ilmenau (Germany); Hannappel, T., E-mail: thomas.hannappel@tu-ilmenau.de [Technische Universität Ilmenau, Institut für Physik, 98693 Ilmenau (Germany); Helmholtz-Zentrum Berlin, Institut für Solare Brennstoffe, 14109 Berlin (Germany)

    2017-01-15

    Highlights: • We investigate the Si(111) surface prepared in CVD ambient at 1000 °C in 950 mbar H{sub 2}. • UHV-based XPS, LEED, STM and FTIR as well as ambient AFM are applied. • After processing the Si(111) surface is free of contamination and atomically flat. • The surface exhibits a (1 × 1) reconstruction and monohydride termination. • Wet-chemical pretreatment and homoepitaxy are required for a regular step structure. - Abstract: For well-defined heteroepitaxial growth of III-V epilayers on Si(111) substrates the atomic structure of the silicon surface is an essential element. Here, we study the preparation of the Si(111) surface in H{sub 2}-based chemical vapor ambient as well as its atomic structure after contamination-free transfer to ultrahigh vacuum (UHV). Applying complementary UHV-based techniques, we derive a complete picture of the atomic surface structure and its chemical composition. X-ray photoelectron spectroscopy measurements after high-temperature annealing confirm a Si surface free of any traces of oxygen or other impurities. The annealing in H{sub 2} ambient leads to a monohydride surface termination, as verified by Fourier-transform infrared spectroscopy. Scanning tunneling microscopy confirms a well ordered, atomically smooth surface, which is (1 × 1) reconstructed, in agreement with low energy electron diffraction patterns. Atomic force microscopy reveals a significant influence of homoepitaxy and wet-chemical pretreatment on the surface morphology. Our findings show that wet-chemical pretreatment followed by high-temperature annealing leads to contamination-free, atomically flat Si(111) surfaces, which are ideally suited for subsequent III-V heteroepitaxy.

  18. Method of doping a semiconductor

    International Nuclear Information System (INIS)

    Yang, C.Y.; Rapp, R.A.

    1983-01-01

    A method is disclosed 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

  19. Fundamentals of semiconductor lasers

    CERN Document Server

    Numai, Takahiro

    2015-01-01

    This book explains physics under the operating principles of semiconductor lasers in detail based on the experience of the author, dealing with the first manufacturing of phase-shifted DFB-LDs and recent research on transverse modes.   The book also bridges a wide gap between journal papers and textbooks, requiring only an undergraduate-level knowledge of electromagnetism and quantum mechanics, and helps readers to understand journal papers where definitions of some technical terms vary, depending on the paper. Two definitions of the photon density in the rate equations and two definitions of the phase-shift in the phase-shifted DFB-LD are explained, and differences in the calculated results are indicated, depending on the definitions.    Readers can understand the physics of semiconductor lasers and analytical tools for Fabry-Perot LDs, DFB-LDs, and VCSELs and will be stimulated to develop semiconductor lasers themselves.

  20. Coherent dynamics in semiconductors

    DEFF Research Database (Denmark)

    Hvam, Jørn Märcher

    1998-01-01

    enhanced in quantum confined lower-dimensional systems, where exciton and biexciton effects dominate the spectra even at room temperature. The coherent dynamics of excitons are at modest densities well described by the optical Bloch equations and a number of the dynamical effects known from atomic......Ultrafast nonlinear optical spectroscopy is used to study the coherent dynamics of optically excited electron-hole pairs in semiconductors. Coulomb interaction implies that the optical inter-band transitions are dominated, at least at low temperatures, by excitonic effects. They are further...... and molecular systems are found and studied in the exciton-biexciton system of semiconductors. At densities where strong exciton interactions, or many-body effects, become dominant, the semiconductor Bloch equations present a more rigorous treatment of the phenomena Ultrafast degenerate four-wave mixing is used...

  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. 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...

  3. Advanced single-wafer sequential multiprocessing techniques for semiconductor device fabrication

    International Nuclear Information System (INIS)

    Moslehi, M.M.; Davis, C.

    1989-01-01

    Single-wafer integrated in-situ multiprocessing (SWIM) is recognized as the future trend for advanced microelectronics production in flexible fast turn- around computer-integrated semiconductor manufacturing environments. The SWIM equipment technology and processing methodology offer enhanced equipment utilization, improved process reproducibility and yield, and reduced chip manufacturing cost. They also provide significant capabilities for fabrication of new and improved device structures. This paper describes the SWIM techniques and presents a novel single-wafer advanced vacuum multiprocessing technology developed based on the use of multiple process energy/activation sources (lamp heating and remote microwave plasma) for multilayer epitaxial and polycrystalline semiconductor as well as dielectric film processing. Based on this technology, multilayer in-situ-doped homoepitaxial silicon and heteroepitaxial strained layer Si/Ge x Si 1 - x /Si structures have been grown and characterized. The process control and the ultimate interfacial abruptness of the layer-to-layer transition widths in the device structures prepared by this technology will challenge the MBE techniques in multilayer epitaxial growth applications

  4. 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

  5. Superconductivity in doped semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    Bustarret, E., E-mail: Etienne.bustarret@neel.cnrs.fr

    2015-07-15

    A historical survey of the main normal and superconducting state properties of several semiconductors doped into superconductivity is proposed. This class of materials includes selenides, tellurides, oxides and column-IV semiconductors. Most of the experimental data point to a weak coupling pairing mechanism, probably phonon-mediated in the case of diamond, but probably not in the case of strontium titanate, these being the most intensively studied materials over the last decade. Despite promising theoretical predictions based on a conventional mechanism, the occurrence of critical temperatures significantly higher than 10 K has not been yet verified. However, the class provides an enticing playground for testing theories and devices alike.

  6. Semiconductor opto-electronics

    CERN Document Server

    Moss, TS; Ellis, B

    1972-01-01

    Semiconductor Opto-Electronics focuses on opto-electronics, covering the basic physical phenomena and device behavior that arise from the interaction between electromagnetic radiation and electrons in a solid. The first nine chapters of this book are devoted to theoretical topics, discussing the interaction of electromagnetic waves with solids, dispersion theory and absorption processes, magneto-optical effects, and non-linear phenomena. Theories of photo-effects and photo-detectors are treated in detail, including the theories of radiation generation and the behavior of semiconductor lasers a

  7. Ternary chalcopyrite semiconductors

    CERN Document Server

    Shay, J L; Pamplin, B R

    2013-01-01

    Ternary Chalcopyrite Semiconductors: Growth, Electronic Properties, and Applications covers the developments of work in the I-III-VI2 and II-IV-V2 ternary chalcopyrite compounds. This book is composed of eight chapters that focus on the crystal growth, characterization, and applications of these compounds to optical communications systems. After briefly dealing with the status of ternary chalcopyrite compounds, this book goes on describing the crystal growth of II-IV-V2 and I-III-VI2 single crystals. Chapters 3 and 4 examine the energy band structure of these semiconductor compounds, illustrat

  8. Compound semiconductor device physics

    CERN Document Server

    Tiwari, Sandip

    2013-01-01

    This book provides one of the most rigorous treatments of compound semiconductor device physics yet published. A complete understanding of modern devices requires a working knowledge of low-dimensional physics, the use of statistical methods, and the use of one-, two-, and three-dimensional analytical and numerical analysis techniques. With its systematic and detailed**discussion of these topics, this book is ideal for both the researcher and the student. Although the emphasis of this text is on compound semiconductor devices, many of the principles discussed will also be useful to those inter

  9. Introductory semiconductor device physics

    CERN Document Server

    Parker, Greg

    2004-01-01

    ATOMS AND BONDINGThe Periodic TableIonic BondingCovalent BondingMetallic bondingvan der Waals BondingStart a DatabaseENERGY BANDS AND EFFECTIVE MASSSemiconductors, Insulators and MetalsSemiconductorsInsulatorsMetalsThe Concept of Effective MassCARRIER CONCENTRATIONS IN SEMICONDUCTORSDonors and AcceptorsFermi-LevelCarrier Concentration EquationsDonors and Acceptors Both PresentCONDUCTION IN SEMICONDUCTORSCarrier DriftCarrier MobilitySaturated Drift VelocityMobility Variation with TemperatureA Derivation of Ohm's LawDrift Current EquationsSemiconductor Band Diagrams with an Electric Field Presen

  10. Effect of dislocations on the open-circuit voltage, short-circuit current and efficiency of heteroepitaxial indium phosphide solar cells

    Science.gov (United States)

    Jain, Raj K.; Flood, Dennis J.

    1990-01-01

    Excellent radiation resistance of indium phosphide solar cells makes them a promising candidate for space power applications, but the present high cost of starting substrates may inhibit their large scale use. Thin film indium phosphide cells grown on Si or GaAs substrates have exhibited low efficiencies, because of the generation and propagation of large number of dislocations. Dislocation densities were calculated and its influence on the open circuit voltage, short circuit current, and efficiency of heteroepitaxial indium phosphide cells was studied using the PC-1D. Dislocations act as predominant recombination centers and are required to be controlled by proper transition layers and improved growth techniques. It is shown that heteroepitaxial grown cells could achieve efficiencies in excess of 18 percent AMO by controlling the number of dislocations. The effect of emitter thickness and surface recombination velocity on the cell performance parameters vs. dislocation density is also studied.

  11. Tunable radiation emitting semiconductor device

    NARCIS (Netherlands)

    2009-01-01

    A tunable radiation emitting semiconductor device includes at least one elongated structure at least partially fabricated from one or more semiconductor materials exhibiting a bandgap characteristic including one or more energy transitions whose energies correspond to photon energies of light

  12. Physical principles of semiconductor detectors

    International Nuclear Information System (INIS)

    Micek, S.L.

    1979-01-01

    The general properties of semiconductors with respect to the possibilities of their use as the ionization radiation detectors are discussed. Some chosen types of semiconductor junctions and their characteristics are briefly presented. There are also discussed the physical phenomena connected with the formation of barriers in various types of semiconductor counters. Finally, the basic properties of three main types of semiconductor detectors are given. (author)

  13. Metal semiconductor contacts and devices

    CERN Document Server

    Cohen, Simon S; Einspruch, Norman G

    1986-01-01

    VLSI Electronics Microstructure Science, Volume 13: Metal-Semiconductor Contacts and Devices presents the physics, technology, and applications of metal-semiconductor barriers in digital integrated circuits. The emphasis is placed on the interplay among the theory, processing, and characterization techniques in the development of practical metal-semiconductor contacts and devices.This volume contains chapters that are devoted to the discussion of the physics of metal-semiconductor interfaces and its basic phenomena; fabrication procedures; and interface characterization techniques, particularl

  14. 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

  15. Depletion field focusing in semiconductors

    NARCIS (Netherlands)

    Prins, M.W.J.; Gelder, Van A.P.

    1996-01-01

    We calculate the three-dimensional depletion field profile in a semiconductor, for a planar semiconductor material with a spatially varying potential upon the surface, and for a tip-shaped semiconductor with a constant surface potential. The nonuniform electric field gives rise to focusing or

  16. Nonlinear Elasticity of Doped Semiconductors

    Science.gov (United States)

    2017-02-01

    AFRL-RY-WP-TR-2016-0206 NONLINEAR ELASTICITY OF DOPED SEMICONDUCTORS Mark Dykman and Kirill Moskovtsev Michigan State University...2016 4. TITLE AND SUBTITLE NONLINEAR ELASTICITY OF DOPED SEMICONDUCTORS 5a. CONTRACT NUMBER FA8650-16-1-7600 5b. GRANT NUMBER 5c. PROGRAM...vibration amplitude. 15. SUBJECT TERMS semiconductors , microresonators, microelectromechanical 16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF

  17. Semi-conductor rectifiers

    International Nuclear Information System (INIS)

    1981-01-01

    A method is described for treating a semiconductor rectifier, comprising: heating the rectifier to a temperature in the range of 100 0 C to 500 0 C, irradiating the rectifier while maintaining its temperature within the said range, and then annealing the rectifier at a temperature of between 280 0 C and 350 0 C for between two and ten hours. (author)

  18. Semiconductor detector physics

    International Nuclear Information System (INIS)

    Equer, B.

    1987-01-01

    Comprehension of semiconductor detectors follows comprehension of some elements of solid state physics. They are recalled here, limited to the necessary physical principles, that is to say the conductivity. P-n and MIS junctions are discussed in view of their use in detection. Material and structure (MOS, p-n, multilayer, ..) are also reviewed [fr

  19. Electronic Properties of Metallic Nanoclusters on Semiconductor Surfaces: Implications for Nanoelectronic Device Applications

    International Nuclear Information System (INIS)

    Lee, Takhee; Liu Jia; Chen, N.-P.; Andres, R.P.; Janes, D.B.; Reifenberger, R.

    2000-01-01

    We review current research on the electronic properties of nanoscale metallic islands and clusters deposited on semiconductor substrates. Reported results for a number of nanoscale metal-semiconductor systems are summarized in terms of their fabrication and characterization. In addition to the issues faced in large-area metal-semiconductor systems, nano-systems present unique challenges in both the realization of well-controlled interfaces at the nanoscale and the ability to adequately characterize their electrical properties. Imaging by scanning tunneling microscopy as well as electrical characterization by current-voltage spectroscopy enable the study of the electrical properties of nanoclusters/semiconductor systems at the nanoscale. As an example of the low-resistance interfaces that can be realized, low-resistance nanocontacts consisting of metal nanoclusters deposited on specially designed ohmic contact structures are described. To illustrate a possible path to employing metal/semiconductor nanostructures in nanoelectronic applications, we also describe the fabrication and performance of uniform 2-D arrays of such metallic clusters on semiconductor substrates. Using self-assembly techniques involving conjugated organic tether molecules, arrays of nanoclusters have been formed in both unpatterned and patterned regions on semiconductor surfaces. Imaging and electrical characterization via scanning tunneling microscopy/spectroscopy indicate that high quality local ordering has been achieved within the arrays and that the clusters are electronically coupled to the semiconductor substrate via the low-resistance metal/semiconductor interface

  20. Class renormalization: islands around islands

    International Nuclear Information System (INIS)

    Meiss, J.D.

    1986-01-01

    An orbit of 'class' is one that rotates about a periodic orbit of one lower class with definite frequency. This contrasts to the 'level' of a periodic orbit which is the number of elements in its continued fraction expansion. Level renormalization is conventionally used to study the structure of quasi-periodic orbits. The scaling structure of periodic orbits encircling other periodic orbits in area preserving maps is discussed here. Fixed points corresponding to the accumulation of p/q bifurcations are found and scaling exponents determined. Fixed points for q > 2 correspond to self-similar islands around islands. Frequencies of the island boundary circles at the fixed points are obtained. Importance of this scaling for the motion of particles in stochastic regions is emphasized. (author)

  1. Single frequency semiconductor lasers

    CERN Document Server

    Fang, Zujie; Chen, Gaoting; Qu, Ronghui

    2017-01-01

    This book systematically introduces the single frequency semiconductor laser, which is widely used in many vital advanced technologies, such as the laser cooling of atoms and atomic clock, high-precision measurements and spectroscopy, coherent optical communications, and advanced optical sensors. It presents both the fundamentals and characteristics of semiconductor lasers, including basic F-P structure and monolithic integrated structures; interprets laser noises and their measurements; and explains mechanisms and technologies relating to the main aspects of single frequency lasers, including external cavity lasers, frequency stabilization technologies, frequency sweeping, optical phase locked loops, and so on. It paints a clear, physical picture of related technologies and reviews new developments in the field as well. It will be a useful reference to graduate students, researchers, and engineers in the field.

  2. Basic semiconductor physics

    CERN Document Server

    Hamaguchi, Chihiro

    2017-01-01

    This book presents a detailed description of basic semiconductor physics. The text covers a wide range of important phenomena in semiconductors, from the simple to the advanced. Four different methods of energy band calculations in the full band region are explained: local empirical pseudopotential, non-local pseudopotential, KP perturbation and tight-binding methods. The effective mass approximation and electron motion in a periodic potential, Boltzmann transport equation and deformation potentials used for analysis of transport properties are discussed. Further, the book examines experiments and theoretical analyses of cyclotron resonance in detail. Optical and transport properties, magneto-transport, two-dimensional electron gas transport (HEMT and MOSFET) and quantum transport are reviewed, while optical transition, electron-phonon interaction and electron mobility are also addressed. Energy and electronic structure of a quantum dot (artificial atom) are explained with the help of Slater determinants. The...

  3. Semiconductor physics an introduction

    CERN Document Server

    Seeger, Karlheinz

    1999-01-01

    Semiconductor Physics - An Introduction - is suitable for the senior undergraduate or new graduate student majoring in electrical engineering or physics. It will also be useful to solid-state scientists and device engineers involved in semiconductor design and technology. The text provides a lucid account of charge transport, energy transport and optical processes, and a detailed description of many devices. It includes sections on superlattices and quantum well structures, the effects of deep-level impurities on transport, the quantum Hall effect and the calculation of the influence of a magnetic field on the carrier distribution function. This 6th edition has been revised and corrected, and new sections have been added to different chapters.

  4. Three dimensional strained semiconductors

    Science.gov (United States)

    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.

  5. Compound semiconductor device modelling

    CERN Document Server

    Miles, Robert

    1993-01-01

    Compound semiconductor devices form the foundation of solid-state microwave and optoelectronic technologies used in many modern communication systems. In common with their low frequency counterparts, these devices are often represented using equivalent circuit models, but it is often necessary to resort to physical models in order to gain insight into the detailed operation of compound semiconductor devices. Many of the earliest physical models were indeed developed to understand the 'unusual' phenomena which occur at high frequencies. Such was the case with the Gunn and IMPATI diodes, which led to an increased interest in using numerical simulation methods. Contemporary devices often have feature sizes so small that they no longer operate within the familiar traditional framework, and hot electron or even quantum­ mechanical models are required. The need for accurate and efficient models suitable for computer aided design has increased with the demand for a wider range of integrated devices for operation at...

  6. Optically coupled semiconductor device

    Energy Technology Data Exchange (ETDEWEB)

    Kumagaya, Naoki

    1988-11-18

    This invention concerns an optically coupled semiconductor device using the light as input signal and a MOS transistor for the output side in order to control on-off of the output side by the input signal which is insulated from the output. Concerning this sort of element, when a MOS transistor and a load resistance are planned to be accumulated on the same chip, a resistor and control of impurity concentration of the channel, etc. become necessary despite that the only formation of a simple P-N junction is enough, for a solar cell, hence cost reduction thereof cannot be done. In order to remove this defect, this invention offers an optically coupled semiconductor device featuring that two solar cells are connected in reverse parallel between the gate sources of the output MOS transistors and an operational light emitting element is individually set facing a respective solar cell. 4 figs.

  7. 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)

  8. Images through semiconductors

    International Nuclear Information System (INIS)

    Anon.

    1986-01-01

    Improved image processing techniques are constantly being developed for television and for scanners using X-rays or other radiation for industrial or medical applications, etc. As Erik Heijne of CERN explains here, particle physics too has its own special requirements for image processing. The increasing use of semiconductor techniques for handling measurements down to the level of a few microns provides another example of the close interplay between scientific research and technological development. (orig.).

  9. Muonium states in semiconductors

    International Nuclear Information System (INIS)

    Patterson, B.D.

    1987-01-01

    There is a brief summary of what is known about the muonium states isotropic, anisotropic and diamagnetic in diamond and zincblende semiconductors. The report deals with muonium spectroscopy, including the formation probabilities, hyperfine parameters and electronic g-factors of the states. The dynamics of the states is treated including a discussion of the transition from isotropic Mu to anisotropic Mu in diamond, temperature-dependent linewidthes in silicon and germanium and effects of daping and radiation damage

  10. Nonradiative recombination in semiconductors

    CERN Document Server

    Abakumov, VN; Yassievich, IN

    1991-01-01

    In recent years, great progress has been made in the understandingof recombination processes controlling the number of excessfree carriers in semiconductors under nonequilibrium conditions. As a result, it is now possible to give a comprehensivetheoretical description of these processes. The authors haveselected a number of experimental results which elucidate theunderlying physical problems and enable a test of theoreticalmodels. The following topics are dealt with: phenomenological theory ofrecombination, theoretical models of shallow and deep localizedstates, cascade model of carrier captu

  11. Doping of organic semiconductors

    International Nuclear Information System (INIS)

    Luessem, B.; Riede, M.; Leo, K.

    2013-01-01

    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)

  12. Isotopically controlled semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    Haller, Eugene E.

    2006-06-19

    The following article is an edited transcript based on the Turnbull Lecture given by Eugene E. Haller at the 2005 Materials Research Society Fall Meeting in Boston on November 29, 2005. The David Turnbull Lectureship is awarded to recognize the career of a scientist who has made outstanding contributions to understanding materials phenomena and properties through research, writing, and lecturing, as exemplified by the life work of David Turnbull. Haller was named the 2005 David Turnbull Lecturer for his 'pioneering achievements and leadership in establishing the field of isotopically engineered semiconductors; for outstanding contributions to materials growth, doping and diffusion; and for excellence in lecturing, writing, and fostering international collaborations'. The scientific interest, increased availability, and technological promise of highly enriched isotopes have led to a sharp rise in the number of experimental and theoretical studies with isotopically controlled semiconductor crystals. This article reviews results obtained with isotopically controlled semiconductor bulk and thin-film heterostructures. Isotopic composition affects several properties such as phonon energies, band structure, and lattice constant in subtle, but, for their physical understanding, significant ways. Large isotope-related effects are observed for thermal conductivity in local vibrational modes of impurities and after neutron transmutation doping. Spectacularly sharp photoluminescence lines have been observed in ultrapure, isotopically enriched silicon crystals. Isotope multilayer structures are especially well suited for simultaneous self- and dopant-diffusion studies. The absence of any chemical, mechanical, or electrical driving forces makes possible the study of an ideal random-walk problem. Isotopically controlled semiconductors may find applications in quantum computing, nanoscience, and spintronics.

  13. 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...

  14. Semiconductor Ion Implanters

    International Nuclear Information System (INIS)

    MacKinnon, Barry A.; Ruffell, John P.

    2011-01-01

    In 1953 the Raytheon CK722 transistor was priced at $7.60. Based upon this, an Intel Xeon Quad Core processor containing 820,000,000 transistors should list at $6.2 billion! Particle accelerator technology plays an important part in the remarkable story of why that Intel product can be purchased today for a few hundred dollars. Most people of the mid twentieth century would be astonished at the ubiquity of semiconductors in the products we now buy and use every day. Though relatively expensive in the nineteen fifties they now exist in a wide range of items from high-end multicore microprocessors like the Intel product to disposable items containing 'only' hundreds or thousands like RFID chips and talking greeting cards. This historical development has been fueled by continuous advancement of the several individual technologies involved in the production of semiconductor devices including Ion Implantation and the charged particle beamlines at the heart of implant machines. In the course of its 40 year development, the worldwide implanter industry has reached annual sales levels around $2B, installed thousands of dedicated machines and directly employs thousands of workers. It represents in all these measures, as much and possibly more than any other industrial application of particle accelerator technology. This presentation discusses the history of implanter development. It touches on some of the people involved and on some of the developmental changes and challenges imposed as the requirements of the semiconductor industry evolved.

  15. The Physics of Semiconductors

    Science.gov (United States)

    Brennan, Kevin F.

    1999-02-01

    Modern fabrication techniques have made it possible to produce semiconductor devices whose dimensions are so small that quantum mechanical effects dominate their behavior. This book describes the key elements of quantum mechanics, statistical mechanics, and solid-state physics that are necessary in understanding these modern semiconductor devices. The author begins with a review of elementary quantum mechanics, and then describes more advanced topics, such as multiple quantum wells. He then disusses equilibrium and nonequilibrium statistical mechanics. Following this introduction, he provides a thorough treatment of solid-state physics, covering electron motion in periodic potentials, electron-phonon interaction, and recombination processes. The final four chapters deal exclusively with real devices, such as semiconductor lasers, photodiodes, flat panel displays, and MOSFETs. The book contains many homework exercises and is suitable as a textbook for electrical engineering, materials science, or physics students taking courses in solid-state device physics. It will also be a valuable reference for practicing engineers in optoelectronics and related areas.

  16. Effects of Pretreatment on the Electronic Properties of Plasma Enhanced Chemical Vapor Deposition Hetero-Epitaxial Graphene Devices

    Science.gov (United States)

    Zhang, Lian-Chang; Shi, Zhi-Wen; Yang, Rong; Huang, Jian

    2014-09-01

    Quasi-monolayer graphene is successfully grown by the plasma enhanced chemical vapor deposition heteroepitaxial method we reported previously. To measure its electrical properties, the prepared graphene is fabricated into Hall ball shaped devices by the routine micro-fabrication method. However, impurity molecules adsorbed onto the graphene surface will impose considerable doping effects on the one-atom-thick film material. Our experiment demonstrates that pretreatment of the device by heat radiation baking and electrical annealing can dramatically influence the doping state of the graphene and consequently modify the electrical properties. While graphene in the as-fabricated device is highly p-doped, as confirmed by the position of the Dirac point at far more than +60 V, baking treatment at temperatures around 180°C can significantly lower the doping level and reduce the conductivity. The following electrical annealing is much more efficient to desorb the extrinsic molecules, as confirmed by the in situ measurement, and as a result, further modify the doping state and electrical properties of the graphene, causing a considerable drop of the conductivity and a shifting of Dirac point from beyond +60 V to 0 V.

  17. The crystal orientation relation and macroscopic surface roughness in hetero-epitaxial graphene grown on Cu/mica

    International Nuclear Information System (INIS)

    Qi, J L; Nagashio, K; Nishimura, T; Toriumi, A

    2014-01-01

    Clean, flat and orientation-identified graphene on a substrate is in high demand for graphene electronics. In this study, the hetero-epitaxial graphene growth on Cu(111)/mica(001) by chemical vapor deposition is investigated to check the applicability for top-gate insulator research on graphene, as well as graphene channel research, by transferring graphene on to SiO 2 /Si substrates. After adjusting the graphene growth conditions, the surface roughness of the graphene/Cu/mica substrate and the average smoothed areas are ∼0.34 nm and ∼100 μm 2 , respectively. The orientation of graphene in the graphene/Cu/mica substrate can be identified by the hexagonal void morphology of Cu. Moreover, we demonstrate a relatively high mobility of ∼4500 cm 2 V −1 s −1 in graphene transferred on the SiO 2 /Si substrate. These results suggest that the present graphene/Cu/mica substrate can be used for top-gate insulator research on graphene. (papers)

  18. Influence of stress on morphology and magnetism of heteroepitaxial thin films

    International Nuclear Information System (INIS)

    Wedler, G.

    2001-01-01

    In this thesis the method of the bending-beam technique and the scanning tunnel microscopy was used in order to study the influence of mechanical stresses on growth and magnetoelastic coupling of selected epitaxial thin-layer systems. The Si x Ge 1-x alloy films deposited at 900 K on Si(001) substrates with Si concentrations 20% a change of the stress-behaviour is observed, which lets conclude to pure 3D island growth without wetting layer. Scanning-tunnel-microscopy studies show already at intermediate film thicknesses of 1 nm regular islands with a narrow size distribution. For the explanation of this surprising change of the growth modus the influence of kinetic parameters is discussed. Furthermore for the first time stress measurements of Fe/ GaAs(001) are presented. The behaviour of the film stress at 450 K hints to a few nm thick interdiffusion layer between film and substrate. This interdiffusion is at 300 K only by about 30% reduced and cannot by this be neglected anywhere. By means of on different substrates [Mg(001), lowly stressed Cr(001) buffer layer, GaAs(001)] growed Fe films for the first time a detailed picture of the stress dependence of the magnetoelastic coupling constants B 1 and B 2 of Fe in the layer-density range of 2-100 mm is presented. While the coupling constants of stress-free Fe(001) films exhibit volume behaviour, distinct deviations occur already at small stresses of about 0.1 GPa; at some GPa even the sign changes. The value of B 2 decreases linearly with the film stress up to 6 GPa, in B 1 after an initially linear slope above 2-3 GPa a saturation occurs. Magnetization and magnetic anisotropy however behave in whole studied layer-density range as in the volume

  19. Electrodes for Semiconductor Gas Sensors

    Science.gov (United States)

    Lee, Sung Pil

    2017-01-01

    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. PMID:28346349

  20. Development of semiconductor electronics

    International Nuclear Information System (INIS)

    Bardeen, John.

    1977-01-01

    In 1931, Wilson applied Block's theory about the energy bands for the motion of electrons in a crystal lattice to semiconductors and showed that conduction can take place in two different ways, by electrons and by holes. Not long afterwards Frenkel showed that these carriers can flow by diffusion in a concentration gradient as well as under the influence of an electric field and wrote down equations for the current flow. The third major contribution, in the late 1930's was the explanation of rectification at a metalsemiconductor contact by Mott and more completely by Schottky. In late 1947 the first transistor of the point contact type was invented by Brattin, Shockley and Bardeen. Then after single crystals of Ge were grown, the junction transistor was developed by the same group. The first silicon transistors appeared in 1954. Then an important step was discovery of the planar transistor by Hoenri in 1960 which led to development of integrated circuits by 1962. Many transistors are produced by batch processing on a slice of silicon. Then in 1965 Mos (Metal-Oxide Semiconductor) transistor and in 1968 LSI (Large Scale Intergration circuits) were developed. Aside from electronic circuits, there are many other applications of semiconductors, including junction power rectifiers, junction luminescence (including lasers), solar batteries, radiation detectors, microwave oscillators and charged-coupled devices for computer memories and devices. One of the latest developments is a microprocessor with thousands of transistors and associated circuitry on a single small chip of silicon. It can be programmed to provide a variety of circuit functions, thus it is not necessary to go through the great expense of LSI's for each desired function, but to use standard microprocessors and program to do the job

  1. Layered semiconductor neutron detectors

    Science.gov (United States)

    Mao, Samuel S; Perry, Dale L

    2013-12-10

    Room temperature operating solid state hand held neutron detectors integrate one or more relatively thin layers of a high neutron interaction cross-section element or materials with semiconductor detectors. The high neutron interaction cross-section element (e.g., Gd, B or Li) or materials comprising at least one high neutron interaction cross-section element can be in the form of unstructured layers or micro- or nano-structured arrays. Such architecture provides high efficiency neutron detector devices by capturing substantially more carriers produced from high energy .alpha.-particles or .gamma.-photons generated by neutron interaction.

  2. Basic properties of semiconductors

    CERN Document Server

    Landsberg, PT

    2013-01-01

    Since Volume 1 was published in 1982, the centres of interest in the basic physics of semiconductors have shifted. Volume 1 was called Band Theory and Transport Properties in the first edition, but the subject has broadened to such an extent that Basic Properties is now a more suitable title. Seven chapters have been rewritten by the original authors. However, twelve chapters are essentially new, with the bulk of this work being devoted to important current topics which give this volume an almost encyclopaedic form. The first three chapters discuss various aspects of modern band theory and the

  3. Electrowetting on semiconductors

    Science.gov (United States)

    Palma, Cesar; Deegan, Robert

    2015-01-01

    Applying a voltage difference between a conductor and a sessile droplet sitting on a thin dielectric film separating it from the conductor will cause the drop to spread. When the conductor is a good metal, the change of the drop's contact angle due to the voltage is given by the Young-Lippmann (YL) equation. Here, we report experiments with lightly doped, single crystal silicon as the conductive electrode. We derive a modified YL equation that includes effects due to the semiconductor and contact line pinning. We show that light induces a non-reversible wetting transition, and that our model agrees well with our experimental results.

  4. Semiconductor ionizino. radiation detectors

    International Nuclear Information System (INIS)

    1982-01-01

    Spectrometric semiconductor detectors of ionizing radiation with the electron-hole junction, based on silicon and germanium are presented. The following parameters are given for the individual types of germanium detectors: energy range of detected radiation, energy resolution given as full width at half maximum (FWHM) and full width at one tenth of maximum (FWTM) for 57 Co and 60 Co, detection sensitivity, optimal voltage, and electric capacitance at optimal voltage. For silicon detectors the value of FWHM for 239 Pu is given, the sensitive area and the depth of the sensitive area. (E.S.)

  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. Single filament semiconductor laser

    International Nuclear Information System (INIS)

    Botez, D.

    1980-01-01

    A semiconductor laser comprising: a body of semiconductor material including a substrate having a surface and a pair of spaced, substantially parallel dove-tailed shaped grooves in said surface, said body having a pair of end surfaces between which said grooves extend, said end surfaces being reflective to light with at least one of said end surfaces being partially transparent to light a first epitaxial layer over said surface of the substrate and the surfaces of the grooves, said first epitaxial layer having a flat surface portion over the portion of the substrate surface between the grooves, a thin second epitaxial layer over said first epitaxial layer, a third epitaxial layer over said second epitaxial layer, said first and third epitaxial layers being of opposite conductivity types and the second epitaxial layer being the active recombination region of the laser with the light being generated therein in the vicinity of the portion which is over the flat surface portion of the first epitaxial layer, and a pair of contacts on said body with one contact being over said third epitaxial body and the other being on said substrate

  7. Epitaxy of Polar Oxides and Semiconductors

    Science.gov (United States)

    Shelton, Christopher Tyrel

    remarkable surface morphologies. This work represents the first effort to extend SAE and CAE to true bulk single-crystal GaN substrates. By carefully controlling supersaturation during growth it is possible to prepare confined areas with a range of step densities, including surfaces that are entirely step-free. Single terrace GaN mesas up to 100 m in size have been observed, however the potential exists, due to the extremely low dislocation density of the substrate, to further extend the dimensions of these regions. Step-free GaN templates are ideal substrates for rocksalt heteroepitaxy and solve a long-standing challenge related to the integration of cubic and hexagonal materials. It has been previously observed that the origin of the two in-plane orientations in rocksalts grown on III-nitrides is a consequence of the stepped GaN surface. By using a substrate that is effectively step-free across a 100 m region, it is possible to prepare a rocksalt // GaN film with a single in-plane orientation. Heterojunctions of this type are disclination defect free and highly crystalline. The ability to locally prepare a single orientation rocksalt film, coupled with commensurate 2D layer-by-layer growth techniques, allows growth, for the first time, of a truly 'semiconductor-grade' oxide-nitride interface. To study the transport properties of oxide-nitride heterostructures, a series of experiments on standard GaN // sapphire template layers were conducted. Devices that allowed contact to the buried oxide-nitride interface were prepared and characterized using low-temperature Hall measurements. Although a high mobility 2DEG was not observed in these samples, a conduction path at the lattice matched Mg0.52Ca0.48O // GaN interface did appear. If confirmed, this finding could represent the first evidence for interfacial polar coupling between an oxide and a nitride. Overcoming the significant symmetry, chemistry and bonding environment barriers to forming a structurally perfect oxide

  8. II-VI semiconductor compounds

    CERN Document Server

    1993-01-01

    For condensed matter physicists and electronic engineers, this volume deals with aspects of II-VI semiconductor compounds. Areas covered include devices and applications of II-VI compounds; Co-based II-IV semi-magnetic semiconductors; and electronic structure of strained II-VI superlattices.

  9. Electronic structure of semiconductor interfaces

    Energy Technology Data Exchange (ETDEWEB)

    Herman, F

    1983-02-01

    The study of semiconductor interfaces is one of the most active and exciting areas of current semiconductor research. Because interfaces play a vital role in modern semiconductor technology (integrated circuits, heterojunction lasers, solar cells, infrared detectors, etc.), there is a strong incentive to understand interface properties at a fundamental level and advance existing technology thereby. At the same time, technological advances such as molecular beam epitaxy have paved the way for the fabrication of semiconductor heterojunctions and superlattices of novel design which exhibit unusual electronic, optical, and magnetic properties and offer unique opportunities for fundamental scientific research. A general perspective on this subject is offered treating such topics as the atomic and electronic structure of semiconductor surfaces and interfaces; oxidation and oxide layers; semiconductor heterojunctions and superlattices; rectifying metal-semiconductor contacts; and interface reactions. Recent progress is emphasized and some future directions are indicated. In addition, the role that large-scale scientific computation has played in furthering our theoretical understanding of semiconductor surfaces and interfaces is discussed. Finally, the nature of theoretical models, and the role they play in describing the physical world is considered.

  10. Quantum transport in semiconductor nanowires

    NARCIS (Netherlands)

    Van Dam, J.

    2006-01-01

    This thesis describes a series of experiments aimed at understanding the low-temperature electrical transport properties of semiconductor nanowires. The semiconductor nanowires (1-100 nm in diameter) are grown from nanoscale gold particles via a chemical process called vapor-liquid-solid (VLS)

  11. 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.

  12. Progress in semiconductor drift detectors

    International Nuclear Information System (INIS)

    Rehak, P.; Walton, J.; Gatti, E.

    1985-01-01

    Progress in testing semiconductor drift detectors is reported. Generally better position and energy resolutions were obtained than resolutions published previously. The improvement is mostly due to new electronics better matched to different detectors. It is shown that semiconductor drift detectors are becoming versatile and reliable detectors for position and energy measurements

  13. Semiconductor materials and their properties

    NARCIS (Netherlands)

    Reinders, Angelina H.M.E.; Verlinden, Pierre; van Sark, Wilfried; Freundlich, Alexandre; Reinders, Angele; Verlinden, Pierre; van Sark, Wilfried; Freundlich, Alexandre

    2017-01-01

    Semiconductor materials are the basic materials which are used in photovoltaic (PV) devices. This chapter introduces solid-state physics and semiconductor properties that are relevant to photovoltaics without spending too much time on unnecessary information. Usually atoms in the group of

  14. Optical coherent control in semiconductors

    DEFF Research Database (Denmark)

    Østergaard, John Erland; Vadim, Lyssenko; Hvam, Jørn Märcher

    2001-01-01

    of quantum control including the recent applications to semiconductors and nanostructures. We study the influence of inhomogeneous broadening in semiconductors on CC results. Photoluminescence (PL) and the coherent emission in four-wave mixing (FWM) is recorded after resonant excitation with phase...

  15. Terahertz Nonlinear Optics in Semiconductors

    DEFF Research Database (Denmark)

    Turchinovich, Dmitry; Hvam, Jørn Märcher; Hoffmann, Matthias C.

    2013-01-01

    We demonstrate the nonlinear optical effects – selfphase modulation and saturable absorption of a single-cycle THz pulse in a semiconductor. Resulting from THz-induced modulation of Drude plasma, these nonlinear optical effects, in particular, lead to self-shortening and nonlinear spectral...... breathing of a single-cycle THz pulse in a semiconductor....

  16. Electronic structure of semiconductor interfaces

    International Nuclear Information System (INIS)

    Herman, F.

    1983-01-01

    The study of semiconductor interfaces is one of the most active and exciting areas of current semiconductor research. Because interfaces play a vital role in modern semiconductor technology (integrated circuits, heterojunction lasers, solar cells, infrared detectors, etc.), there is a strong incentive to understand interface properties at a fundamental level and advance existing technology thereby. At the same time, technological advances such as molecular beam epitaxy have paved the way for the fabrication of semiconductor heterojunctions and superlattices of novel design which exhibit unusual electronic, optical, and magnetic properties and offer unique opportunities for fundamental scientific research. A general perspective on this subject is offered treating such topics as the atomic and electronic structure of semiconductor surfaces and interfaces; oxidation and oxide layers; semiconductor heterojunctions and superlattices; rectifying metal-semiconductor contacts; and interface reactions. Recent progress is emphasized and some future directions are indicated. In addition, the role that large-scale scientific computation has played in furthering our theoretical understanding of semiconductor surfaces and interfaces is discussed. Finally, the nature of theoretical models, and the role they play in describing the physical world is considered. (Author) [pt

  17. In-situ Ga doping of fully strained Ge1-xSnx heteroepitaxial layers grown on Ge(001) substrates

    International Nuclear Information System (INIS)

    Shimura, Y.; Takeuchi, S.; Nakatsuka, O.; Vincent, B.; Gencarelli, F.; Clarysse, T.; Vandervorst, W.; Caymax, M.; Loo, R.; Jensen, A.; Petersen, D.H.; Zaima, S.

    2012-01-01

    We have investigated the Ga and Sn content dependence of the crystallinity and electrical properties of Ga-doped Ge 1-x Sn x layers that are heteroepitaxially grown on Ge(001) substrates. The doping of Ga to levels as high as the solubility limit of Ga at the growth temperature leads to the introduction of dislocations, due to the increase in the strain of the Ge 1-x Sn x layers. We achieved the growth of a fully strained Ge 0.922 Sn 0.078 layer on Ge with a Ga concentration of 5.5 × 10 19 /cm 3 without any dislocations and stacking faults. The resistivity of the Ga-doped Ge 1-x Sn x layer decreased as the Sn content was increased. This decrease was due to an increase in the carrier concentration, with an increase in the activation level of Ga atoms in the Ge 1-x Sn x epitaxial layers being induced by the introduction of Sn. As a result, we found that the resistivity for the Ge 0.950 Sn 0.050 layer annealed at 600°C for 1 min is 3.6 times less than that of the Ga-doped Ge/Ge sample. - Highlights: ► Heavy Ga-doping into fully strained GeSn layers without the introduction of dislocations ► The uniform Ga depth profile allowed the introduction of Sn ► The decrease in resistivity with an increase in the activation level of Ga was caused by the introduction of Sn

  18. Effect of hydrogen flow on growth of 3C-SiC heteroepitaxial layers on Si(111) substrates

    International Nuclear Information System (INIS)

    Yan, Guoguo; Zhang, Feng; Niu, Yingxi; Yang, Fei; Liu, Xingfang; Wang, Lei; Zhao, Wanshun; Sun, Guosheng; Zeng, Yiping

    2015-01-01

    Highlights: • 3C-SiC thin films of preferential orientation along with Si(111) substrates were obtained using home-made horizontal LPCVD with different H_2 flow rate ranging from15 to 30 slm. • High H_2 flow rate will inhibit the out-diffusion of silicon atoms from silicon substrates effectively. Transformation and the mechanism of void formation are discussed based on our model. • The variation of growth rate and n-type doping with increasing H_2 flow rate is researched and the influencing mechanism is discussed. - Abstract: 3C-SiC thin films were grown on Si(111) substrates at 1250 °C by horizontal low pressure chemical vapor deposition (LPCVD). We performed an exhaustive study on the effect of H_2 flow rate on the crystalline quality, surface morphologies, growth rate, n-type doping of 3C-SiC thin films and the voids at the interface. The films show epitaxial nature with high crystal quality and surface morphology increase obviously with increasing H_2 flow rate. The growth rate and n-type doping are also dependent on H_2 flow rate. The properties of the voids at the interface are discussed based on the cross-sectional scanning electron microscope characterization. Transformation of voids with increasing H_2 flow rate are attributed to higher 3C-SiC film growth rate and H_2 etching rate. The mechanism of void formation is discussed based on our model, too. The results demonstrate that H_2 flow rate plays a very important role in the heteroepitaxial growth of 3C-SiC films.

  19. Local heteroepitaxy as an adhesion mechanism in aluminium coatings cold gas sprayed on AlN substrates

    International Nuclear Information System (INIS)

    Wüstefeld, Christina; Rafaja, David; Motylenko, Mykhaylo; Ullrich, Christiane; Drehmann, Rico; Grund, Thomas; Lampke, Thomas; Wielage, Bernhard

    2017-01-01

    Cold gas sprayed Al coatings deposited onto wurtzitic AlN substrates show excellent adhesion. As a possible adhesion mechanism, the local heteroepitaxy between Al and AlN was considered and verified experimentally in Al coatings, which were deposited using magnetron sputtering or cold gas spraying on single-crystalline and polycrystalline AlN substrates. Analysis of the local orientation relationships at the Al/AlN interfaces revealed that preferentially such lattice planes of Al align parallel with the upright lattice planes of AlN, which possess similar interplanar distances. The matching lattice planes in the Al coatings grew as continuations of the lattice planes in the AlN substrates. In all samples under study, the parallel alignment of the lattice planes {220}_A_l and {110}_A_l_N was found. Additional orientation relationships between Al and AlN arose if parallel lattice planes with similar interplanar spacing could be found in both counterparts via rotation of the lattice planes {220}_A_l around their normal direction. Still, the oriented growth of Al on AlN is only possible if Al atoms in the deposited coatings are mobile enough to rearrange along the AlN surface. Whereas the mobility of Al atoms in a magnetron sputtering process is expected to be sufficiently high, the intrinsic mobility of Al atoms in the cold gas sprayed particles is anticipated to be low. However, the auxiliary microstructure analyses have shown that local recrystallization and partial melting are two phenomena, which can facilitate the rearrangement of Al atoms within the cold gas sprayed coating.

  20. Effect of hydrogen flow on growth of 3C-SiC heteroepitaxial layers on Si(111) substrates

    Energy Technology Data Exchange (ETDEWEB)

    Yan, Guoguo [Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083 (China); Zhang, Feng, E-mail: fzhang@semi.ac.cn [Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083 (China); Niu, Yingxi; Yang, Fei [Electrical Engineering New Materials and Microelectronics Department, State Grid Smart Grid Research Institute, Beijing 100192 (China); Liu, Xingfang; Wang, Lei; Zhao, Wanshun [Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083 (China); Sun, Guosheng [Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083 (China); Dongguan Tianyu Semiconductor, Inc., Dongguan 523000 (China); Zeng, Yiping [Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083 (China)

    2015-10-30

    Highlights: • 3C-SiC thin films of preferential orientation along with Si(111) substrates were obtained using home-made horizontal LPCVD with different H{sub 2} flow rate ranging from15 to 30 slm. • High H{sub 2} flow rate will inhibit the out-diffusion of silicon atoms from silicon substrates effectively. Transformation and the mechanism of void formation are discussed based on our model. • The variation of growth rate and n-type doping with increasing H{sub 2} flow rate is researched and the influencing mechanism is discussed. - Abstract: 3C-SiC thin films were grown on Si(111) substrates at 1250 °C by horizontal low pressure chemical vapor deposition (LPCVD). We performed an exhaustive study on the effect of H{sub 2} flow rate on the crystalline quality, surface morphologies, growth rate, n-type doping of 3C-SiC thin films and the voids at the interface. The films show epitaxial nature with high crystal quality and surface morphology increase obviously with increasing H{sub 2} flow rate. The growth rate and n-type doping are also dependent on H{sub 2} flow rate. The properties of the voids at the interface are discussed based on the cross-sectional scanning electron microscope characterization. Transformation of voids with increasing H{sub 2} flow rate are attributed to higher 3C-SiC film growth rate and H{sub 2} etching rate. The mechanism of void formation is discussed based on our model, too. The results demonstrate that H{sub 2} flow rate plays a very important role in the heteroepitaxial growth of 3C-SiC films.

  1. 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.)

  2. KMC Simulation of Surface Growth of Semiconductors

    International Nuclear Information System (INIS)

    Esen, M.

    2004-01-01

    In this work we have studied the growth and equilibration of semiconductor surfaces consisting of monoatomic steps separated by flat terraces using kinetic Monte Carlo method. Atomistic processes such as diffusion on terraces, attachment/detachment particles to/from step edges, attachment of particles from an upper terrace to a bounding step, diffusion of particles along step edges are considered. A rate equation for each, these processes is written and the overall transition probabilities are calculated where processes are ordered to make the distinction between slow and fast processes Iractal The interaction of steps is also included in the calculation of rate equations. The growth of such a surface is simulated when there is a particle flux to the surface. The rough of the surface and its dependence on both temperature and kinetic parameters such edge diffusion barrier are investigated. The formation of islands on terraces is prohibited and the distribution of their number and sizes are investigated as a function of temperature and appropriate kinetic parameters. In the absence of a flux to the surface, the equilibration of the surface is investigated paying particular attention to the top of the profile when the initial surface is a periodic profile where parallel monoatomic steps separated by terraces. It is observed that during equilibration of the profile, the topmost step disintegrates quickly and leads to many islands on the top of the profile due to. collision and annihilation of step edges of opposite sign. The islands then quickly disintegrate due to the line tension effect and this scenario repeats itself until the surface completely flattens

  3. Ion implantation for semiconductors

    International Nuclear Information System (INIS)

    Grey-Morgan, T.

    1995-01-01

    Full text: Over the past two decades, thousands of particle accelerators have been used to implant foreign atoms like boron, phosphorus and arsenic into silicon crystal wafers to produce special embedded layers for manufacturing semiconductor devices. Depending on the device required, the atomic species, the depth of implant and doping levels are the main parameters for the implantation process; the selection and parameter control is totally automated. The depth of the implant, usually less than 1 micron, is determined by the ion energy, which can be varied between 2 and 600 keV. The ion beam is extracted from a Freeman or Bernas type ion source and accelerated to 60 keV before mass analysis. For higher beam energies postacceleration is applied up to 200 keV and even higher energies can be achieved by mass selecting multiplycharged ions, but with a corresponding reduction in beam output. Depending on the device to be manufactured, doping levels can range from 10 10 to 10 15 atoms/cm 2 and are controlled by implanter beam currents in the range up to 30mA; continuous process monitoring ensures uniformity across the wafer of better than 1 % . As semiconductor devices get smaller, additional sophistication is required in the design of the implanter. The silicon wafers charge electrically during implantation and this charge must be dissipated continuously to reduce the electrical stress in the device and avoid destructive electrical breakdown. Electron flood guns produce low energy electrons (below 10 electronvolts) to neutralize positive charge buildup and implanter design must ensure minimum contamination by other isotopic species and ensure low internal sputter rates. The pace of technology in the semiconductor industry is such that implanters are being built now for 256 Megabit circuits but which are only likely to be widely available five years from now. Several specialist companies manufacture implanter systems, each costing around US$5 million, depending on the

  4. Semiconductor radiation detector

    Science.gov (United States)

    Bell, Zane W.; Burger, Arnold

    2010-03-30

    A semiconductor detector for ionizing electromagnetic radiation, neutrons, and energetic charged particles. The detecting element is comprised of a compound having the composition I-III-VI.sub.2 or II-IV-V.sub.2 where the "I" component is from column 1A or 1B of the periodic table, the "II" component is from column 2B, the "III" component is from column 3A, the "IV" component is from column 4A, the "V" component is from column 5A, and the "VI" component is from column 6A. The detecting element detects ionizing radiation by generating a signal proportional to the energy deposited in the element, and detects neutrons by virtue of the ionizing radiation emitted by one or more of the constituent materials subsequent to capture. The detector may contain more than one neutron-sensitive component.

  5. Semiconductor testing method

    International Nuclear Information System (INIS)

    Brown, Stephen.

    1992-01-01

    In a method of avoiding use of nuclear radiation, eg gamma rays, X-rays, electron beams, for testing semiconductor components for resistance to hard radiation, which hard radiation causes data corruption in some memory devices and 'latch-up' in others, similar fault effects can be achieved using a xenon or other 'light' flash gun even though the penetration of light is significantly less than that of gamma rays. The method involves treating a device with gamma radiation, measuring a particular fault current at the onset of a fault event, repeating the test with light to confirm the occurrence of the fault event at the same measured fault current, and using the fault current value as a reference for future tests using light on similar devices. (author)

  6. Radial semiconductor drift chambers

    International Nuclear Information System (INIS)

    Rawlings, K.J.

    1987-01-01

    The conditions under which the energy resolution of a radial semiconductor drift chamber based detector system becomes dominated by the step noise from the detector dark current have been investigated. To minimise the drift chamber dark current attention should be paid to carrier generation at Si/SiO 2 interfaces. This consideration conflicts with the desire to reduce the signal risetime: a higher drift field for shorter signal pulses requires a larger area of SiO 2 . Calculations for the single shaping and pseudo Gaussian passive filters indicate that for the same degree of signal risetime sensitivity in a system dominated by the step noise from the detector dark current, the pseudo Gaussian filter gives only a 3% improvement in signal/noise and 12% improvement in rate capability compared with the single shaper performance. (orig.)

  7. Energy distribution in semiconductors

    International Nuclear Information System (INIS)

    Ance, C.

    1979-01-01

    For various semiconductors the dispersive energy Esub(d) defined in the Wemple-Didomenico model is connected with the covalent and ionic energies Esub(h) and C. A continuous curve of ionicity against the ratio of the two energies Esub(A) and Esub(B), connected to Esub(h) and C is reported. Afromowitz's model is applied to the ternary compounds Gasub(1-x)Alsub(x)Sb using optical decomposition. From these results the average energy gap Esub(g) is given by Esub(g) = D 0 M 0 sup((IB))/(epsilon 1 (0)-1) where M 0 sup((IB)) is the interband transition contribution to the optical moment M 0 . (author)

  8. Organic Semiconductor Photovoltaics

    Science.gov (United States)

    Sariciftci, Niyazi Serdar

    2005-03-01

    Recent developments on organic photovoltaic elements are reviewed. Semiconducting conjugated polymers and molecules as well as nanocrystalline inorganic semiconductors are used in composite thin films. The photophysics of such photoactive devices is based on the photoinduced charge transfer from donor type semiconducting molecules onto acceptor type molecules such as Buckminsterfullerene, C60 and/or nanoparticles. Similar to the first steps in natural photosynthesis, this photoinduced electron transfer leads to a number of potentially interesting applications which include sensitization of the photoconductivity and photovoltaic phenomena. Examples of photovoltaic architectures are discussed with their potential in terrestrial solar energy conversion. Several materials are introduced and discussed for their photovoltaic activities. Furthermore, nanomorphology has been investigated with AFM, SEM and TEM. The morphology/property relationship for a given photoactive system is found to be a major effect.

  9. Tenarife Island, Canary Island Archipelago, Atlantic Ocean

    Science.gov (United States)

    1991-01-01

    Tenarife Island is one of the most volcanically active of the Canary Island archipelago, Atlantic Ocean, just off the NW coast of Africa, (28.5N, 16.5W). The old central caldera, nearly filled in by successive volcanic activity culminating in two stratocones. From those two peaks, a line of smaller cinder cones extend to the point of the island. Extensive gullies dissect the west side of the island and some forests still remain on the east side.

  10. Numerical analysis of temperature profile and thermal-stress during excimer laser induced heteroepitaxial growth of patterned amorphous silicon and germanium bi-layers deposited on Si(100)

    Energy Technology Data Exchange (ETDEWEB)

    Conde, J.C., E-mail: jconde@uvigo.e [Dpto. Fisica Aplicada, E.T.S.I.I. University of Vigo, Campus Universitario, Rua Maxwell s/n, E-36310 Vigo (Spain); Martin, E. [Dpto. de Mecanica, Maquinas y Motores Termicos y Fluidos, E.T.S.I.I. University of Vigo, Campus Universitario, Rua Maxwell s/n, E-36310 Vigo (Spain); Gontad, F.; Chiussi, S. [Dpto. Fisica Aplicada, E.T.S.I.I. University of Vigo, Campus Universitario, Rua Maxwell s/n, E-36310 Vigo (Spain); Fornarini, L. [Enea-Frascati, Via Enrico Fermi 45, I-00044 Frascati (Roma) (Italy); Leon, B. [Dpto. Fisica Aplicada, E.T.S.I.I. University of Vigo, Campus Universitario, Rua Maxwell s/n, E-36310 Vigo (Spain)

    2010-02-26

    A Finite Element Method (FEM) study of the coupled thermal-stress during the heteroepitaxial growth induced by excimer laser radiation of patterned amorphous hydrogenated silicon (a-Si:H) and germanium (a-Ge:H) bi-layers deposited on a Si(100) wafer is presented. The ArF (193 nm) excimer laser provides high energy densities during very short laser pulse (20 ns) provoking, at the same time, melting and solidification phenomena in the range of several tenths of nanoseconds. These phenomena play an important role during the growth of heteroepitaxial SiGe structures characterized by high Ge concentration buried under a Si rich surface. In addition, the thermal-stresses that appear before the melting and after the solidification processes can also affect to the epitaxial growth of high quality SiGe alloys in these patterned structures and, in consequence, it is necessary to predict their effects. The aim of this work is to estimate the energy threshold and the corresponding thermal-stresses in the interfaces and the borders of these patterned structures.

  11. ZnO Nanorod-Induced Heteroepitaxial Growth of SOD Type Co-Based Zeolitic Imidazolate Framework Membranes for H2 Separation.

    Science.gov (United States)

    Nian, Pei; Li, Yujia; Zhang, Xiang; Cao, Yi; Liu, Haiou; Zhang, Xiongfu

    2018-01-31

    Up to now, the fabrication of well-intergrown Co-based zeolitic imidazolate framework (ZIF) membranes on porous tubular supports is still a major challenge. We report here a heteroepitaxial growth for preparing well-intergrown Co-based ZIFs (ZIF-67 and ZIF-9) tubular membranes with high performance and excellent thermal stability by employing a thin layer of ZnO nanorods acting as both nucleation centers and anchor sites for the growth of metal-organic framework membranes. The results show that well-intergrown Co-ZIF-67 and Co-ZIF-9 membranes are successfully achieved on the ZnO nanorod-modified porous ceramic tubes. This highly active heteroepitaxial growth may be attributed to the fact that the (Zn,Co) hydroxy double salt intermediate produced in situ from ZnO nanorods acts as heteroseeds and enables the uniform growth of Co-based membranes. The H 2 /CO 2 selectivity of the as-prepared Co-ZIF-9 tubular membrane could reach about 23.8 and the H 2 /CH 4 selectivity of Co-ZIF-67 tubular membrane is as high as 45.4. Moreover, the membranes demonstrate excellent stability because of the ZnO nanorods as linkers between the membrane and substrate.

  12. Hetero-epitaxial growth of TiC films on MgO(001) at 100 °C by DC reactive magnetron sputtering

    International Nuclear Information System (INIS)

    Braic, M.; Zoita, N.C.; Danila, M.; Grigorescu, C.E.A.; Logofatu, C.

    2015-01-01

    Hetero-epitaxial TiC thin films were deposited at 100 °C on MgO(001) by DC reactive magnetron sputtering in a mixture of Ar and CH 4 . The 62 nm thick films were analyzed for elemental composition and chemical bonding by Auger electron spectroscopy, X-ray photoelectron spectroscopy and micro-Raman spectroscopy. The crystallographic structure investigation by high resolution X-ray diffraction revealed that the films consist of two layers: an interface partially strained epilayer with high crystalline quality, and a relaxed layer, formed by columnar grains, maintaining the epitaxial relationship with the substrate. The films presented smooth surfaces (RMS roughness ~ 0.55 nm), with circular equi-sized grains/crystallites, as observed by atomic force microscopy. The Hall measurements in Van der Pauw geometry revealed relatively high resistivity value ~ 620 μΩ cm, ascribed to electron scattering on interfaces, on grain boundaries and on different defects/dislocations. - Highlights: • Hetero-epitaxial TiC 0.84 thin films were grown on MgO(001) at 100 °C by magnetron sputtering. • 62 nm thick films were synthesized by magnetron sputtering, using Ti, Ar and CH 4 . • The film comprises a partially strained interface epilayer and a relaxed top layer. • Both layers preserve the epitaxial relationship with the substrate. • Low RMS surface roughness ~ 0.55 nm and grains with mean lateral size of ~ 38.5 nm were observed

  13. Numerical analysis of temperature profile and thermal-stress during excimer laser induced heteroepitaxial growth of patterned amorphous silicon and germanium bi-layers deposited on Si(100)

    International Nuclear Information System (INIS)

    Conde, J.C.; Martin, E.; Gontad, F.; Chiussi, S.; Fornarini, L.; Leon, B.

    2010-01-01

    A Finite Element Method (FEM) study of the coupled thermal-stress during the heteroepitaxial growth induced by excimer laser radiation of patterned amorphous hydrogenated silicon (a-Si:H) and germanium (a-Ge:H) bi-layers deposited on a Si(100) wafer is presented. The ArF (193 nm) excimer laser provides high energy densities during very short laser pulse (20 ns) provoking, at the same time, melting and solidification phenomena in the range of several tenths of nanoseconds. These phenomena play an important role during the growth of heteroepitaxial SiGe structures characterized by high Ge concentration buried under a Si rich surface. In addition, the thermal-stresses that appear before the melting and after the solidification processes can also affect to the epitaxial growth of high quality SiGe alloys in these patterned structures and, in consequence, it is necessary to predict their effects. The aim of this work is to estimate the energy threshold and the corresponding thermal-stresses in the interfaces and the borders of these patterned structures.

  14. Hetero-epitaxial growth of TiC films on MgO(001) at 100 °C by DC reactive magnetron sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Braic, M. [National Institute for Optoelectronics, 409 Atomistilor St., 077125 Magurele (Romania); Zoita, N.C., E-mail: cnzoita@inoe.ro [National Institute for Optoelectronics, 409 Atomistilor St., 077125 Magurele (Romania); Danila, M. [National Institute for Research and Development in Microtechnology, 126A Erou Iancu Nicolae Blvd., 077190 Bucharest (Romania); Grigorescu, C.E.A. [National Institute for Optoelectronics, 409 Atomistilor St., 077125 Magurele (Romania); Logofatu, C. [National Institute of Materials Physics, 105 bis Atomistilor St., 077125 Magurele (Romania)

    2015-08-31

    Hetero-epitaxial TiC thin films were deposited at 100 °C on MgO(001) by DC reactive magnetron sputtering in a mixture of Ar and CH{sub 4}. The 62 nm thick films were analyzed for elemental composition and chemical bonding by Auger electron spectroscopy, X-ray photoelectron spectroscopy and micro-Raman spectroscopy. The crystallographic structure investigation by high resolution X-ray diffraction revealed that the films consist of two layers: an interface partially strained epilayer with high crystalline quality, and a relaxed layer, formed by columnar grains, maintaining the epitaxial relationship with the substrate. The films presented smooth surfaces (RMS roughness ~ 0.55 nm), with circular equi-sized grains/crystallites, as observed by atomic force microscopy. The Hall measurements in Van der Pauw geometry revealed relatively high resistivity value ~ 620 μΩ cm, ascribed to electron scattering on interfaces, on grain boundaries and on different defects/dislocations. - Highlights: • Hetero-epitaxial TiC{sub 0.84} thin films were grown on MgO(001) at 100 °C by magnetron sputtering. • 62 nm thick films were synthesized by magnetron sputtering, using Ti, Ar and CH{sub 4}. • The film comprises a partially strained interface epilayer and a relaxed top layer. • Both layers preserve the epitaxial relationship with the substrate. • Low RMS surface roughness ~ 0.55 nm and grains with mean lateral size of ~ 38.5 nm were observed.

  15. Magnetic excitations in ferromagnetic semiconductors

    International Nuclear Information System (INIS)

    Furdyna, J.K.; Liu, X.; Zhou, Y.Y.

    2009-01-01

    Magnetic excitations in a series of GaMnAs ferromagnetic semiconductor films were studied by ferromagnetic resonance (FMR). Using the FMR approach, multi-mode spin wave resonance spectra have been observed, whose analysis provides information on magnetic anisotropy (including surface anisotropy), distribution of magnetization precession within the GaMnAs film, dynamic surface spin pinning (derived from surface anisotropy), and the value of exchange stiffness constant D. These studies illustrate a combination of magnetism and semiconductor physics that is unique to magnetic semiconductors

  16. 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.

  17. State of the art in semiconductor detectors

    International Nuclear Information System (INIS)

    Rehak, P.; Gatti, E.

    1990-01-01

    The state of the art in semiconductor detectors for elementary particle physics and X-ray astronomy is briefly reviewed. Semiconductor detectors are divided into two groups; i) classical semiconductor diode detectors and ii) semiconductor memory detectors. Principles of signal formation for both groups of detectors are described and their performance is compared. New developments of silicon detectors are reported here. (orig.)

  18. State of the art in semiconductor detectors

    International Nuclear Information System (INIS)

    Rehak, P.; Gatti, E.

    1989-01-01

    The state of the art in semiconductor detectors for elementary particle physics and x-ray astronomy is briefly reviewed. Semiconductor detectors are divided into two groups; classical semiconductor diode detectors; and semiconductor memory detectors. Principles of signal formation for both groups of detectors are described and their performance is compared. New developments of silicon detectors are reported here. 13 refs., 8 figs

  19. Semiconductor device comprising a pn-heterojunction

    NARCIS (Netherlands)

    2007-01-01

    An electric device is disclosed comprising a pn-heterojunction ( 4 ) formed by a nanowire ( 3 ) of 111 -V semiconductor material and a semiconductor body ( 1 ) comprising a group IV semiconductor material. The nanowire ( 3 ) is positioned in direct contact with the surface ( 2 ) of the semiconductor

  20. Toward designing semiconductor-semiconductor heterojunctions for photocatalytic applications

    Science.gov (United States)

    Zhang, Liping; Jaroniec, Mietek

    2018-02-01

    Semiconductor photocatalysts show a great potential for environmental and energy-related applications, however one of the major disadvantages is their relatively low photocatalytic performance due to the recombination of electron-hole pairs. Therefore, intensive research is being conducted toward design of heterojunctions, which have been shown to be effective for improving the charge-transfer properties and efficiency of photocatalysts. According to the type of band alignment and direction of internal electric field, heterojunctions are categorized into five different types, each of which is associated with its own charge transfer characteristics. Since the design of heterojunctions requires the knowledge of band edge positions of component semiconductors, the commonly used techniques for the assessment of band edge positions are reviewed. Among them the electronegativity-based calculation method is applied for a large number of popular visible-light-active semiconductors, including some widely investigated bismuth-containing semiconductors. On basis of the calculated band edge positions and the type of component semiconductors reported, heterojunctions composed of the selected bismuth-containing semiconductors are proposed. Finally, the most popular synthetic techniques for the fabrication of heterojunctions are briefly discussed.

  1. Method of manufacturing a semiconductor device and semiconductor device obtained with such a method

    NARCIS (Netherlands)

    2008-01-01

    The invention relates to a method of manufacturing a semiconductor device (10) with a semiconductor body (1) which is provided with at least one semiconductor element, wherein on the surface of the semiconductor body (1) a mesa- shaped semiconductor region (2) is formed, a masking layer (3) is

  2. Selective, electrochemical etching of a semiconductor

    Science.gov (United States)

    Dahal, Rajendra P.; Bhat, Ishwara B.; Chow, Tat-Sing

    2018-03-20

    Methods for facilitating fabricating semiconductor structures are provided which include: providing a multilayer structure including a semiconductor layer, the semiconductor layer including a dopant and having an increased conductivity; selectively increasing, using electrochemical processing, porosity of the semiconductor layer, at least in part, the selectively increasing porosity utilizing the increased conductivity of the semiconductor layer; and removing, at least in part, the semiconductor layer with the selectively increased porosity from the multilayer structure. By way of example, the selectively increasing porosity may include selectively, anodically oxidizing, at least in part, the semiconductor layer of the multilayer structure.

  3. Metal-insulator-semiconductor photodetectors.

    Science.gov (United States)

    Lin, Chu-Hsuan; Liu, Chee Wee

    2010-01-01

    The major radiation of the sun can be roughly divided into three regions: ultraviolet, visible, and infrared light. Detection in these three regions is important to human beings. The metal-insulator-semiconductor photodetector, with a simpler process than the pn-junction photodetector and a lower dark current than the MSM photodetector, has been developed for light detection in these three regions. Ideal UV photodetectors with high UV-to-visible rejection ratio could be demonstrated with III-V metal-insulator-semiconductor UV photodetectors. The visible-light detection and near-infrared optical communications have been implemented with Si and Ge metal-insulator-semiconductor photodetectors. For mid- and long-wavelength infrared detection, metal-insulator-semiconductor SiGe/Si quantum dot infrared photodetectors have been developed, and the detection spectrum covers atmospheric transmission windows.

  4. Metal-Insulator-Semiconductor Photodetectors

    Directory of Open Access Journals (Sweden)

    Chu-Hsuan Lin

    2010-09-01

    Full Text Available The major radiation of the Sun can be roughly divided into three regions: ultraviolet, visible, and infrared light. Detection in these three regions is important to human beings. The metal-insulator-semiconductor photodetector, with a simpler process than the pn-junction photodetector and a lower dark current than the MSM photodetector, has been developed for light detection in these three regions. Ideal UV photodetectors with high UV-to-visible rejection ratio could be demonstrated with III-V metal-insulator-semiconductor UV photodetectors. The visible-light detection and near-infrared optical communications have been implemented with Si and Ge metal-insulator-semiconductor photodetectors. For mid- and long-wavelength infrared detection, metal-insulator-semiconductor SiGe/Si quantum dot infrared photodetectors have been developed, and the detection spectrum covers atmospheric transmission windows.

  5. Quantum optics with semiconductor nanostructures

    CERN Document Server

    Jahnke, Frank

    2012-01-01

    A guide to the theory, application and potential of semiconductor nanostructures in the exploration of quantum optics. It offers an overview of resonance fluorescence emission.$bAn understanding of the interaction between light and matter on a quantum level is of fundamental interest and has many applications in optical technologies. The quantum nature of the interaction has recently attracted great attention for applications of semiconductor nanostructures in quantum information processing. Quantum optics with semiconductor nanostructures is a key guide to the theory, experimental realisation, and future potential of semiconductor nanostructures in the exploration of quantum optics. Part one provides a comprehensive overview of single quantum dot systems, beginning with a look at resonance fluorescence emission. Quantum optics with single quantum dots in photonic crystal and micro cavities are explored in detail, before part two goes on to review nanolasers with quantum dot emitters. Light-matter interaction...

  6. Atomic layer deposition for semiconductors

    CERN Document Server

    Hwang, Cheol Seong

    2014-01-01

    This edited volume discusses atomic layer deposition (ALD) for all modern semiconductor devices, moving from the basic chemistry of ALD and modeling of ALD processes to sections on ALD for memories, logic devices, and machines.

  7. Semiconductor technology program. Progress briefs

    Science.gov (United States)

    Bullis, W. M.

    1980-01-01

    Measurement technology for semiconductor materials, process control, and devices is reviewed. Activities include: optical linewidth and thermal resistance measurements; device modeling; dopant density profiles; resonance ionization spectroscopy; and deep level measurements. Standardized oxide charge terminology is also described.

  8. Semiconductor radiation detectors. Device physics

    International Nuclear Information System (INIS)

    Lutz, G.

    2007-01-01

    Starting from basic principles, the author, whose own contributions to these developments have been significant, describes the rapidly growing field of modern semiconductor detectors used for energy and position measurement radiation. This development was stimulated by requirements in elementary particle physics where it has led to important scientific discoveries. It has now spread to many other fields of science and technology. The book is written in a didactic way and includes an introduction to semiconductor physics. The working principles of semiconductor radiation detectors are explained in an intuitive way, followed by formal quantitative analysis. Broad coverage is also given to electronic signal readout and to the subject of radiation damage. The book is the first to comprehensively cover the semiconductor radiation detectors currently in use. It is useful as a teaching guide and as a reference work for research and applications. (orig.)

  9. Self-assembling peptide semiconductors

    Science.gov (United States)

    Tao, Kai; Makam, Pandeeswar; Aizen, Ruth; Gazit, Ehud

    2017-01-01

    Semiconductors are central to the modern electronics and optics industries. Conventional semiconductive materials bear inherent limitations, especially in emerging fields such as interfacing with biological systems and bottom-up fabrication. A promising candidate for bioinspired and durable nanoscale semiconductors is the family of self-assembled nanostructures comprising short peptides. The highly ordered and directional intermolecular π-π interactions and hydrogen-bonding network allow the formation of quantum confined structures within the peptide self-assemblies, thus decreasing the band gaps of the superstructures into semiconductor regions. As a result of the diverse architectures and ease of modification of peptide self-assemblies, their semiconductivity can be readily tuned, doped, and functionalized. Therefore, this family of electroactive supramolecular materials may bridge the gap between the inorganic semiconductor world and biological systems. PMID:29146781

  10. Temperature controller of semiconductor laser

    Czech Academy of Sciences Publication Activity Database

    Matoušek, Vít; Číp, Ondřej

    2003-01-01

    Roč. 73, č. 3 (2003), s. 10 - 12 ISSN 0928-5008 Institutional research plan: CEZ:AV0Z2065902 Keywords : temperature controller * semiconductor laser * laser diode Subject RIV: BH - Optics, Masers, Lasers

  11. Diffusion of small Cu islands on the Ni(111) surface: A self-learning kinetic Monte Carlo study

    Science.gov (United States)

    Acharya, Shree Ram; Shah, Syed Islamuddin; Rahman, Talat S.

    2017-08-01

    We elucidate the diffusion kinetics of a heteroepitaxial system consisting of two-dimensional small (1-8 atoms) Cu islands on the Ni(111) surface at (100-600) K using the Self-Learning Kinetic Monte Carlo (SLKMC-II) method. Study of the statics of the system shows that compact CuN (3≤N≤8) clusters made up of triangular units on fcc occupancy sites are the energetically most stable structures of those clusters. Interestingly, we find a correlation between the height of the activation energy barrier (Ea) and the location of the transition state (TS). The Ea of processes for Cu islands on the Ni(111) surface are in general smaller than those of their counterpart Ni islands on the same surface. We find this difference to correlate with the relative strength of the lateral interaction of the island atoms in the two systems. While our database consists of hundreds of possible processes, we identify and discuss the energetics of those that are the most dominant, or are rate-limiting, or most contributory to the diffusion of the islands. Since the Ea of single- and multi-atom processes that convert compact island shapes into non-compact ones are larger (with a significantly smaller Ea for their reverse processes) than that for the collective (concerted) motion of the island, the later dominate in the system kinetics - except for the cases of the dimer, pentamer and octamer. Short-jump involving one atom, long jump dimer-shearing, and long-jump corner shearing (via a single-atom) are, respectively, the dominating processes in the diffusion of the dimer, pentamer and octamer. Furthermore single-atom corner-rounding are the rate-limiting processes for the pentamer and octamer islands. Comparison of the energetics of selected processes and lateral interactions obtained from semi-empirical interatomic potentials with those from density functional theory show minor quantitative differences and overall qualitative agreement.

  12. Wake fields in semiconductor plasmas

    International Nuclear Information System (INIS)

    Berezhiani, V.I.; Mahajan, S.M.

    1994-05-01

    It is shown that an intense short laser pulse propagating through a semiconductor plasma will generated longitudinal Langmuir waves in its wake. The measurable wake field can be used as a diagnostic to study nonlinear optical phenomena. For narrow gap semiconductors (for examples InSb) with Kane-type dispersion relation, the system can simulate, at currently available laser powers, the physics underlying wake-field accelerators. (author). 9 refs, 1 fig

  13. Semiconductor research with reactor neutrons

    International Nuclear Information System (INIS)

    Kimura, Itsuro

    1992-01-01

    Reactor neutrons play an important role for characterization of semiconductor materials as same as other advanced materials. On the other hand reactor neutrons bring about not only malignant irradiation effects called radiation damage, but also useful effects such as neutron transmutation doping and defect formation for opto-electronics. Research works on semiconductor materials with the reactor neutrons of the Kyoto University Reactor (KUR) are briefly reviewed. In this review, a stress is laid on the present author's works. (author)

  14. Semiconductor crystal high resolution imager

    Science.gov (United States)

    Levin, Craig S. (Inventor); Matteson, James (Inventor)

    2011-01-01

    A radiation imaging device (10). The radiation image device (10) comprises a subject radiation station (12) producing photon emissions (14), and at least one semiconductor crystal detector (16) arranged in an edge-on orientation with respect to the emitted photons (14) to directly receive the emitted photons (14) and produce a signal. The semiconductor crystal detector (16) comprises at least one anode and at least one cathode that produces the signal in response to the emitted photons (14).

  15. Dissipative chaos in semiconductor superlattices

    Directory of Open Access Journals (Sweden)

    F. Moghadam

    2008-03-01

    Full Text Available In this paper the motion of electron in a miniband of a semiconductor superlattice (SSL under the influence of external electric and magnetic fields is investigated. The electric field is applied in a direction perpendicular to the layers of the semiconductor superlattice, and the magnetic field is applied in different direction Numerical calculations show conditions led to the possibility of chaotic behaviors.

  16. Reducing leakage current in semiconductor devices

    Energy Technology Data Exchange (ETDEWEB)

    Lu, Bin; Matioli, Elison de Nazareth; Palacios, Tomas Apostol

    2018-03-06

    A semiconductor device includes a first region having a first semiconductor material and a second region having a second semiconductor material. The second region is formed over the first region. The semiconductor device also includes a current blocking structure formed in the first region between first and second terminals of the semiconductor device. The current blocking structure is configured to reduce current flow in the first region between the first and second terminals.

  17. Optical orientation in ferromagnet/semiconductor hybrids

    International Nuclear Information System (INIS)

    Korenev, V L

    2008-01-01

    The physics of optical pumping of semiconductor electrons in ferromagnet/semiconductor hybrids is discussed. Optically oriented semiconductor electrons detect the magnetic state of a ferromagnetic film. In turn, the ferromagnetism of the hybrid can be controlled optically with the help of a semiconductor. Spin–spin interactions near the ferromagnet/semiconductor interface play a crucial role in the optical readout and the manipulation of ferromagnetism

  18. Optical orientation in ferromagnet/semiconductor hybrids

    Science.gov (United States)

    Korenev, V. L.

    2008-11-01

    The physics of optical pumping of semiconductor electrons in ferromagnet/semiconductor hybrids is discussed. Optically oriented semiconductor electrons detect the magnetic state of a ferromagnetic film. In turn, the ferromagnetism of the hybrid can be controlled optically with the help of a semiconductor. Spin-spin interactions near the ferromagnet/semiconductor interface play a crucial role in the optical readout and the manipulation of ferromagnetism.

  19. Optical Orientation in Ferromagnet/Semiconductor Hybrids

    OpenAIRE

    Korenev, V. L.

    2008-01-01

    The physics of optical pumping of semiconductor electrons in the ferromagnet/semiconductor hybrids is discussed. Optically oriented semiconductor electrons detect the magnetic state of the ferromagnetic film. In turn, the ferromagnetism of the hybrid can be controlled optically with the help of the semiconductor. Spin-spin interactions near the interface ferromagnet/semiconductor play crucial role in the optical readout and the manipulation of ferromagnetism.

  20. Semiconductors for plasmonics and metamaterials

    DEFF Research Database (Denmark)

    Naik, G.V.; Boltasseva, Alexandra

    2010-01-01

    Plasmonics has conventionally been in the realm of metal-optics. However, conventional metals as plasmonic elements in the near-infrared (NIR) and visible spectral ranges suffer from problems such as large losses and incompatibility with semiconductor technology. Replacing metals with semiconduct......Plasmonics has conventionally been in the realm of metal-optics. However, conventional metals as plasmonic elements in the near-infrared (NIR) and visible spectral ranges suffer from problems such as large losses and incompatibility with semiconductor technology. Replacing metals...... with semiconductors can alleviate these problems if only semiconductors could exhibit negative real permittivity. Aluminum doped zinc oxide (AZO) is a low loss semiconductor that can show negative real permittivity in the NIR. A comparative assessment of AZO-based plasmonic devices such as superlens and hyperlens...... with their metal-based counterparts shows that AZO-based devices significantly outperform at a wavelength of 1.55 µm. This provides a strong stimulus in turning to semiconductor plasmonics at the telecommunication wavelengths. (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)....

  1. Ripening of Semiconductor Nanoplatelets.

    Science.gov (United States)

    Ott, Florian D; Riedinger, Andreas; Ochsenbein, David R; Knüsel, Philippe N; Erwin, Steven C; Mazzotti, Marco; Norris, David J

    2017-11-08

    Ostwald ripening describes how the size distribution of colloidal particles evolves with time due to thermodynamic driving forces. Typically, small particles shrink and provide material to larger particles, which leads to size defocusing. Semiconductor nanoplatelets, thin quasi-two-dimensional (2D) particles with thicknesses of only a few atomic layers but larger lateral dimensions, offer a unique system to investigate this phenomenon. Experiments show that the distribution of nanoplatelet thicknesses does not defocus during ripening, but instead jumps sequentially from m to (m + 1) monolayers, allowing precise thickness control. We investigate how this counterintuitive process occurs in CdSe nanoplatelets. We develop a microscopic model that treats the kinetics and thermodynamics of attachment and detachment of monomers as a function of their concentration. We then simulate the growth process from nucleation through ripening. For a given thickness, we observe Ostwald ripening in the lateral direction, but none perpendicular. Thicker populations arise instead from nuclei that capture material from thinner nanoplatelets as they dissolve laterally. Optical experiments that attempt to track the thickness and lateral extent of nanoplatelets during ripening appear consistent with these conclusions. Understanding such effects can lead to better synthetic control, enabling further exploration of quasi-2D nanomaterials.

  2. A semiconductor laser device

    Energy Technology Data Exchange (ETDEWEB)

    Takaro, K.; Naoki, T.; Satosi, K.; Yasutosi, K.

    1984-03-17

    A device is proposed which makes it possible to obtain single vertical mode emission in the absence of noise. Noise suppression is achieved by a method which determines the relationship between the donor densities in the second and third layers of an n type semiconductor laser, and the total output optical emission of layers with respect to the emission from the entire laser. The device consists of a photoresist film with a window applied to a 100 GaAs n type conductivity substrate using a standard method. Chemical etching through this window in the substrate is used to generate a slot approximately 1 micrometer in size. After the photoresist film is removed, the following layers are deposited from the liquid phase onto the substrate in the sequence indicated: a telurium doped protective layer of n type AlxGa(1-x) As; 2) an undoped active p type AlyGa(1-6) As layer and a tellurium doped upper protective n type conductivity GaAs layer.

  3. Semiconductor integrated circuits

    International Nuclear Information System (INIS)

    Michel, A.E.; Schwenker, R.O.; Ziegler, J.F.

    1979-01-01

    An improved method involving ion implantation to form non-epitaxial semiconductor integrated circuits. These are made by forming a silicon substrate of one conductivity type with a recessed silicon dioxide region extending into the substrate and enclosing a portion of the silicon substrate. A beam of ions of opposite conductivity type impurity is directed at the substrate at an energy and dosage level sufficient to form a first region of opposite conductivity within the silicon dioxide region. This impurity having a concentration peak below the surface of the substrate forms a region of the one conductivity type which extends from the substrate surface into the first opposite type region to a depth between the concentration peak and the surface and forms a second region of opposite conductivity type. The method, materials and ion beam conditions are detailed. Vertical bipolar integrated circuits can be made this way when the first opposite type conductivity region will function as a collector. Also circuits with inverted bipolar devices when this first region functions as a 'buried'' emitter region. (U.K.)

  4. Impurity gettering in semiconductors

    Science.gov (United States)

    Sopori, Bhushan L.

    1995-01-01

    A process for impurity gettering in a semiconductor substrate or device such as a silicon substrate or device. The process comprises hydrogenating the substrate or device at the back side thereof with sufficient intensity and for a time period sufficient to produce a damaged back side. Thereafter, the substrate or device is illuminated with electromagnetic radiation at an intensity and for a time period sufficient to cause the impurities to diffuse to the back side and alloy with a metal there present to form a contact and capture the impurities. The impurity gettering process also can function to simultaneously passivate defects within the substrate or device, with the defects likewise diffusing to the back side for simultaneous passivation. Simultaneously, substantially all hydrogen-induced damage on the back side of the substrate or device is likewise annihilated. Also taught is an alternate process comprising thermal treatment after hydrogenation of the substrate or device at a temperature of from about 500.degree. C. to about 700.degree. C. for a time period sufficient to cause the impurities to diffuse to the damaged back side thereof for subsequent capture by an alloying metal.

  5. Semiconductor acceleration sensor

    Science.gov (United States)

    Ueyanagi, Katsumichi; Kobayashi, Mitsuo; Goto, Tomoaki

    1996-09-01

    This paper reports a practical semiconductor acceleration sensor especially suited for automotive air bag systems. The acceleration sensor includes four beams arranged in a swastika structure. Two piezoresistors are formed on each beam. These eight piezoresistors constitute a Wheatstone bridge. The swastika structure of the sensing elements, an upper glass plate and a lower glass plate exhibit the squeeze film effect which enhances air dumping, by which the constituent silicon is prevented from breakdown. The present acceleration sensor has the following features. The acceleration force component perpendicular to the sensing direction can be cancelled. The cross-axis sensitivity is less than 3 percent. And, the erroneous offset caused by the differences between the thermal expansion coefficients of the constituent materials can be canceled. The high aspect ratio configuration realized by plasma etching facilitates reducing the dimensions and improving the sensitivity of the acceleration sensor. The present acceleration sensor is 3.9 mm by 3.9 mm in area and 1.2 mm in thickness. The present acceleration sensor can measure from -50 to +50 G with sensitivity of 0.275 mV/G and with non-linearity of less than 1 percent. The acceleration sensor withstands shock of 3000 G.

  6. Semiconductor lasers stability, instability and chaos

    CERN Document Server

    Ohtsubo, Junji

    2017-01-01

    This book describes the fascinating recent advances made concerning the chaos, stability and instability of semiconductor lasers, and discusses their applications and future prospects in detail. It emphasizes the dynamics in semiconductor lasers by optical and electronic feedback, optical injection, and injection current modulation. Applications of semiconductor laser chaos, control and noise, and semiconductor lasers are also demonstrated. Semiconductor lasers with new structures, such as vertical-cavity surface-emitting lasers and broad-area semiconductor lasers, are intriguing and promising devices. Current topics include fast physical number generation using chaotic semiconductor lasers for secure communication, development of chaos, quantum-dot semiconductor lasers and quantum-cascade semiconductor lasers, and vertical-cavity surface-emitting lasers. This fourth edition has been significantly expanded to reflect the latest developments. The fundamental theory of laser chaos and the chaotic dynamics in se...

  7. Researching Pacific island livelihoods:

    DEFF Research Database (Denmark)

    Egelund Christensen, Andreas; Mertz, Ole

    2010-01-01

    on contemporary theories of nissology and conceptual analytical frameworks for island research. Through a review of selected case-study-based island literature on changing livelihoods coming out of the South Pacific, we wish to illustrate and discuss advantages of finding common grounds for small island studies....... The focus is on two dimensions of island livelihood, migration and natural resource management, both of which are significant contributors in making island livelihoods and shaping Pacific seascapes. We argue that there is still a substantial lack of studies targeting small island dynamics that are empirical...

  8. Heteroepitaxial growth and surface structure of L1{sub 0}-MnGa(111) ultra-thin films on GaN(0001)

    Energy Technology Data Exchange (ETDEWEB)

    Mandru, Andrada-Oana; Wang, Kangkang; Cooper, Kevin; Ingram, David C.; Smith, Arthur R. [Department of Physics and Astronomy, Nanoscale and Quantum Phenomena Institute, Ohio University, Athens, Ohio 45701 (United States); Garcia Diaz, Reyes; Takeuchi, Noboru [Department of Physics and Astronomy, Nanoscale and Quantum Phenomena Institute, Ohio University, Athens, Ohio 45701 (United States); Centro de Nanociencias y Nanotecnologia, Universidad Nacional Autónoma de México, Apartado Postal 14, Ensenada Baja California, Codigo Postal 22800 (Mexico); Haider, Muhammad [Department of Physics and Astronomy, Nanoscale and Quantum Phenomena Institute, Ohio University, Athens, Ohio 45701 (United States); Department of Physics, King Fahd University of Petroleum and Minerals, Dhahran, 31261 (Saudi Arabia)

    2013-10-14

    L1{sub 0}-structured MnGa(111) ultra-thin films were heteroepitaxially grown on GaN(0001) under lightly Mn-rich conditions using molecular beam epitaxy. Room-temperature scanning tunneling microscopy (STM) investigations reveal smooth terraces and angular step edges, with the surface structure consisting primarily of a 2 × 2 reconstruction along with small patches of 1 × 2. Theoretical calculations were carried out using density functional theory, and the simulated STM images were calculated using the Tersoff-Hamman approximation, revealing that a stoichiometric 1 × 2 and a Mn-rich 2 × 2 surface structure give the best agreement with the observed experimental images.

  9. Heteroepitaxial growth of strained multilayer superconducting thin films of Nd1.83Ce0.17CuOx/YBa2Cu3O7-δ

    International Nuclear Information System (INIS)

    Gupta, A.; Gross, R.; Olsson, E.; Segmueller, A.; Koren, G.; Tsuei, C.C.

    1990-01-01

    Heteroepitaxial growth of strained multilayer thin films of YBa 2 Cu 3 O 7-δ /Nd 1.83 Ce 0.17 CuO x by pulsed-laser deposition is reported. The coherency strain results in biaxial compression of the tetragonal Nd 1.83 Ce 0.17 CuO x layers, whereas the biaxial tension in the YBa 2 Cu 3 O 7-δ layers removes the orthorhombic distortion and makes the unit cell isotropic in the basal plane (a=b). Depending on their oxygen content, either the YBa 2 Cu 3 O 7-δ or the Nd 1.83 Ce 0.17 CuO x layers are superconducting in these multilayers. The strain-induced structural modification has a significant influence on the superconducting transition temperature of the YBa 2 Cu 3 O 7-δ layers

  10. Spontaneous orientation-tuning driven by the strain variation in self-assembled ZnO-SrRuO3 heteroepitaxy

    International Nuclear Information System (INIS)

    Zhu, Yuanmin; Liu, Ruirui; Zhan, Qian; Chang, Wei Sea; Yu, Rong; Wei, Tzu-Chiao; He, Jr-Hau; Chu, Ying-Hao

    2015-01-01

    Heteroepitaxial ZnO and SrRuO 3 were grown on SrTiO 3 (111) substrates and formed a self-assembled wurtzite-perovskite nanostructure. Spontaneous orientation-tuning of the SrRuO 3 pillars was observed, with the growth direction changing from [111] SRO to [011] SRO as the film thickness increased, which is attributed to a misfit strain transition from the biaxial strain imposed by the SrTiO 3 substrate to the vertical strain provided by the ZnO matrix. The [011]-SrRuO 3 and [0001]-ZnO combination presents a favorable matching in the nanocomposite films, resulting in higher charge carrier mobility. This vertically integrated configuration and regulation on the crystallographic orientations are expected to be employed in designing multi-functional nanocomposite systems for applications in electronic devices

  11. Spontaneous orientation-tuning driven by the strain variation in self-assembled ZnO-SrRuO3 heteroepitaxy

    KAUST Repository

    Zhu, Yuanmin; Chang, Wei Sea; Yu, Rong; Liu, Ruirui; Wei, Tzu-Chiao; He, Jr-Hau; Chu, Ying-Hao; Zhan, Qian

    2015-01-01

    Heteroepitaxial ZnO and SrRuO3 were grown on SrTiO3 (111) substrates and formed a self-assembled wurtzite-perovskite nanostructure. Spontaneous orientation-tuning of the SrRuO3 pillars was observed, with the growth direction changing from [111]SRO to [011]SRO as the film thickness increased, which is attributed to a misfit strain transition from the biaxial strain imposed by the SrTiO3 substrate to the vertical strain provided by the ZnO matrix. The [011]-SrRuO3 and [0001]-ZnO combination presents a favorable matching in the nanocomposite films, resulting in higher charge carrier mobility. This vertically integrated configuration and regulation on the crystallographic orientations are expected to be employed in designing multi-functional nanocomposite systems for applications in electronic devices.

  12. Spontaneous orientation-tuning driven by the strain variation in self-assembled ZnO-SrRuO3 heteroepitaxy

    KAUST Repository

    Zhu, Yuanmin

    2015-11-09

    Heteroepitaxial ZnO and SrRuO3 were grown on SrTiO3 (111) substrates and formed a self-assembled wurtzite-perovskite nanostructure. Spontaneous orientation-tuning of the SrRuO3 pillars was observed, with the growth direction changing from [111]SRO to [011]SRO as the film thickness increased, which is attributed to a misfit strain transition from the biaxial strain imposed by the SrTiO3 substrate to the vertical strain provided by the ZnO matrix. The [011]-SrRuO3 and [0001]-ZnO combination presents a favorable matching in the nanocomposite films, resulting in higher charge carrier mobility. This vertically integrated configuration and regulation on the crystallographic orientations are expected to be employed in designing multi-functional nanocomposite systems for applications in electronic devices.

  13. Heteroepitaxial Patterned Growth of Vertically Aligned and Periodically Distributed ZnO Nanowires on GaN Using Laser Interference Ablation

    KAUST Repository

    Yuan, Dajun

    2010-08-23

    A simple two-step method of fabricating vertically aligned and periodically distributed ZnO nanowires on gallium nitride (GaN) substrates is described. The method combines laser interference ablation (LIA) and low temperature hydrothermal decomposition. The ZnO nanowires grow heteroepitaxially on unablated regions of GaN over areas spanning 1 cm2, with a high degree of control over size, orientation, uniformity, and periodicity. High resolution transmission electron microscopy and scanning electron microscopy are utilized to study the structural characteristics of the LIA-patterned GaN substrate in detail. These studies reveal the possible mechanism for the preferential, site-selective growth of the ZnO nanowires. The method demonstrates high application potential for wafer-scale integration into sensor arrays, piezoelectric devices, and optoelectronic devices. © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Spontaneous orientation-tuning driven by the strain variation in self-assembled ZnO-SrRuO{sub 3} heteroepitaxy

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Yuanmin; Liu, Ruirui; Zhan, Qian, E-mail: qzhan@mater.ustb.edu.cn [Department of Material Physics and Chemistry, University of Science and Technology Beijing, Beijing 100083 (China); Chang, Wei Sea [School of Engineering, Monash University Malaysia, Bandar Sunway, Selangor 47500 (Malaysia); Yu, Rong [National Center for Electron Microscopy in Beijing, School of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China); Wei, Tzu-Chiao [Institute of Photonics and Optoelectronics and Department of Electrical Engineering, National Taiwan University, Taipei 10617, Taiwan (China); He, Jr-Hau [Electrical Engineering Program, King Abdullah University of Science & Technology (Saudi Arabia); Chu, Ying-Hao [Department of Materials Science and Engineering, National Chiao Tung University, Hsinchu 30010, Taiwan (China); Institute of Physics, Academia Sinica, Taipei 105, Taiwan (China)

    2015-11-09

    Heteroepitaxial ZnO and SrRuO{sub 3} were grown on SrTiO{sub 3} (111) substrates and formed a self-assembled wurtzite-perovskite nanostructure. Spontaneous orientation-tuning of the SrRuO{sub 3} pillars was observed, with the growth direction changing from [111]{sub SRO} to [011]{sub SRO} as the film thickness increased, which is attributed to a misfit strain transition from the biaxial strain imposed by the SrTiO{sub 3} substrate to the vertical strain provided by the ZnO matrix. The [011]-SrRuO{sub 3} and [0001]-ZnO combination presents a favorable matching in the nanocomposite films, resulting in higher charge carrier mobility. This vertically integrated configuration and regulation on the crystallographic orientations are expected to be employed in designing multi-functional nanocomposite systems for applications in electronic devices.

  15. A step-by-step experiment of 3C-SiC hetero-epitaxial growth on 4H-SiC by CVD

    Energy Technology Data Exchange (ETDEWEB)

    Xin, Bin [School of Microelectronics, Xidian University, Key Laboratory of Wide Band-Gap Semiconductor Materials and Devices, Xi’an 710071 (China); Jia, Ren-Xu, E-mail: rxjia@mail.xidian.edu.cn [School of Microelectronics, Xidian University, Key Laboratory of Wide Band-Gap Semiconductor Materials and Devices, Xi’an 710071 (China); Hu, Ji-Chao [School of Microelectronics, Xidian University, Key Laboratory of Wide Band-Gap Semiconductor Materials and Devices, Xi’an 710071 (China); Tsai, Cheng-Ying [Graduate Institute of Electronics Engineering, National Taiwan University, 10617 Taipei, Taiwan (China); Lin, Hao-Hsiung, E-mail: hhlin@ntu.edu.tw [Graduate Institute of Electronics Engineering, National Taiwan University, 10617 Taipei, Taiwan (China); Graduate Institute of Photonics and Optoelectronics, National Taiwan University, 10617 Taipei, Taiwan (China); Zhang, Yu-Ming [School of Microelectronics, Xidian University, Key Laboratory of Wide Band-Gap Semiconductor Materials and Devices, Xi’an 710071 (China)

    2015-12-01

    Highlights: • A step-by-step experiment to investigate the growth mechanism of SiC hetero-epitaxial is proposed. • It has shown protrusive regular “hill” morphology with much lower density of DPB defect in our experiment, which normally were in high density with shallow groove. Based on the defect morphology, an anisotropy migration rate phenomenon of adatoms has been regarded as forming the morphology of DPB defects and a new “DPB defects assist epitaxy” growth mode has been proposed based on Frank-van der Merwe growth mode. - Abstract: To investigate the growth mechanism of hetero-epitaxial SiC, a step-by-step experiment of 3C-SiC epitaxial layers grown on 4H-SiC on-axis substrates by the CVD method are reported in this paper. Four step experiments with four one-quarter 4H-SiC wafers were performed. Optical microscopy and atomic force microscopy (AFM) were used to characterize the morphology of the epitaxial layers. It was previously found that the main factor affecting the epilayer morphology was double-positioning boundary (DPB) defects, which normally were in high density with shallow grooves. However, a protrusive regular “hill” morphology with a much lower density was shown in our experiment in high-temperature growth conditions. The anisotropic migration of adatoms is regarded as forming the morphology of DPB defects, and a new “DPB defects assist epitaxy” growth mode has been proposed based on the Frank-van der Merwe growth mode. Raman spectroscopy and X-ray diffraction were used to examine the polytypes and the quality of the epitaxial layers.

  16. Semiconductor optoelectronic infrared spectroscopy

    International Nuclear Information System (INIS)

    Hollingworth, A.R.

    2001-08-01

    We use spectroscopy to study infrared optoelectronic inter and intraband semiconductor carrier dynamics. The overall aim of this thesis was to study both III-V and Pb chalcogenide material systems in order to show their future potential use in infrared emitters. The effects of bandstructure engineering have been studied in the output characteristics of mid-IR III-V laser diodes to show which processes (defects, radiative, Auger and phonon) dominate and whether non-radiative processes can be suppressed. A new three-beam pump probe experiment was used to investigate interband recombination directly in passive materials. Experiments on PbSe and theory for non-parabolic near-mirror bands and non-degenerate statistics were in good agreement. Comparisons with HgCdTe showed a reduction in the Auger coefficient of 1-2 orders of magnitude in the PbSe. Using Landau confinement to model spatial confinement in quantum dots (QDs) 'phonon bottlenecking' was studied. The results obtained from pump probe and cyclotron resonance saturation measurements showed a clear suppression in the cooling of carriers when Landau level separation was not resonant with LO phonon energy. When a bulk laser diode was placed in a magnetic field to produce a quasi quantum wire device the resulting enhanced differential gain and reduced Auger recombination lowered I th by 30%. This result showed many peaks in the light output which occurred when the LO phonon energy was a multiple of the Landau level separation. This showed for the first time evidence of the phonon bottleneck in a working laser device. A new technique called time resolved optically detected cyclotron resonance, was used as a precursor to finding the carrier dynamics within a spatially confined quantum dot. By moving to the case of a spatial QD using an optically detected intraband resonance it was possible to measure the energy separation interband levels and conduction and valence sublevels within the dot simultaneously. Furthermore

  17. Simulation of semiconductor devices

    International Nuclear Information System (INIS)

    Oriato, D.

    2001-09-01

    In this thesis a drift diffusion model coupled with self-consistent solutions of Poisson's and Schroedinger's equations, is developed and used to investigate the operation of Gunn diodes and GaN-based LEDs. The model also includes parameters derived from Monte Carlo calculations of the simulated devices. In this way the characteristics of a Monte Carlo approach and of a quantum solver are built into a fast and flexible drift-diffusion model that can be used for testing a large number of heterostructure designs in a time-effective way. The full model and its numerical implementation are described in chapter 2. In chapter 3 the theory of Gunn diodes is presented. A basic model of the dynamics of domain formation and domain transport is described with particular regard to accumulation and dipole domains. Several modes of operation of the Gunn device are described, varying from the resonance mode to the quenched mode. Details about transferred electron devices and negative differential resistance in semiconductor materials are given. In chapter 4 results from the simulation of a simple conventional gunn device confirm the importance of the doping condition at the cathode. Accumulation or dipole domains are achieved respectively with high and low doping densities. The limits of a conventional Gunn diode are explained and solved by introducing the heterostructure Gunn diode. This new design consists of a conventional GaAs transit region coupled with an electron launcher at the cathode, made using an AIGaAs heterostructure step. Simulations show the importance of the insertion of a thin highly-doped layer between the transit region and the electron launcher in order to improve device operation. Chapter 5 is an introduction to Ill-nitrides, in particular GaN and its alloy ln-GaN. We outline the discrepancy in the elastic and piezoelectric parameters found in the literature. Strain, dislocations and piezoelectricity are presented as the main features of a InGaN/GaN system

  18. 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...

  19. Introduction to cathodoluminescence in semiconductors

    International Nuclear Information System (INIS)

    Dussac, M.

    1985-01-01

    The use of cathodoluminescence in a scanning electron microscope leads to acquire a spectrum in a place of the sample surface, or to register the intensity profile of a special emission band along a scanning line, or also to realize a map of the irradiated sample. Composition variations can then, at ambient temperature, be determined, also defects can be shown, together with grain joints and dislocations, radiative and non radiative regions can be distinguished and, at low temperature, elementary processes of luminescence can be studied and impurities identified in semiconductors. Through this analysis method is applicable to every insulating or semiconductor material (that is to say to every material having a gap), in this article only crystalline semi-conductor will be studied [fr

  20. Catalysts, Protection Layers, and Semiconductors

    DEFF Research Database (Denmark)

    Chorkendorff, Ib

    2015-01-01

    Hydrogen is the simplest solar fuel to produce and in this presentation we shall give a short overview of the pros and cons of various tandem devices [1]. The large band gap semiconductor needs to be in front, but apart from that we can chose to have either the anode in front or back using either...... acid or alkaline conditions. Since most relevant semiconductors are very prone to corrosion the advantage of using buried junctions and using protection layers offering shall be discussed [2-4]. Next we shall discuss the availability of various catalysts for being coupled to these protections layers...... and how their stability may be evaluated [5, 6]. Examples of half-cell reaction using protection layers for both cathode and anode will be discussed though some of recent examples under both alkaline and acidic conditions. Si is a very good low band gap semiconductor and by using TiO2 as a protection...

  1. High mobility emissive organic semiconductor

    Science.gov (United States)

    Liu, Jie; Zhang, Hantang; Dong, Huanli; Meng, Lingqiang; Jiang, Longfeng; Jiang, Lang; Wang, Ying; Yu, Junsheng; Sun, Yanming; Hu, Wenping; Heeger, Alan J.

    2015-01-01

    The integration of high charge carrier mobility and high luminescence in an organic semiconductor is challenging. However, there is need of such materials for organic light-emitting transistors and organic electrically pumped lasers. Here we show a novel organic semiconductor, 2,6-diphenylanthracene (DPA), which exhibits not only high emission with single crystal absolute florescence quantum yield of 41.2% but also high charge carrier mobility with single crystal mobility of 34 cm2 V−1 s−1. Organic light-emitting diodes (OLEDs) based on DPA give pure blue emission with brightness up to 6,627 cd m−2 and turn-on voltage of 2.8 V. 2,6-Diphenylanthracene OLED arrays are successfully driven by DPA field-effect transistor arrays, demonstrating that DPA is a high mobility emissive organic semiconductor with potential in organic optoelectronics. PMID:26620323

  2. Thiophene-Based Organic Semiconductors.

    Science.gov (United States)

    Turkoglu, Gulsen; Cinar, M Emin; Ozturk, Turan

    2017-10-24

    Thiophene-based π-conjugated organic small molecules and polymers are the research subject of significant current interest owing to their potential use as organic semiconductors in material chemistry. Despite simple and similar molecular structures, the hitherto reported properties of thiophene-based organic semiconductors are rather diverse. Design of high performance organic semiconducting materials requires a thorough understanding of inter- and intra-molecular interactions, solid-state packing, and the influence of both factors on the charge carrier transport. In this chapter, thiophene-based organic semiconductors, which are classified in terms of their chemical structures and their structure-property relationships, are addressed for the potential applications as organic photovoltaics (OPVs), organic field-effect transistors (OFETs) and organic light emitting diodes (OLEDs).

  3. Organic semiconductors in sensor applications

    CERN Document Server

    Malliaras, George; Owens, Róisín

    2008-01-01

    Organic semiconductors offer unique characteristics such as tunability of electronic properties via chemical synthesis, compatibility with mechanically flexible substrates, low-cost manufacturing, and facile integration with chemical and biological functionalities. These characteristics have prompted the application of organic semiconductors and their devices in physical, chemical, and biological sensors. This book covers this rapidly emerging field by discussing both optical and electrical sensor concepts. Novel transducers based on organic light-emitting diodes and organic thin-film transistors, as well as systems-on-a-chip architectures are presented. Functionalization techniques to enhance specificity are outlined, and models for the sensor response are described.

  4. Semiconductors and semimetals epitaxial microstructures

    CERN Document Server

    Willardson, Robert K; Beer, Albert C; Gossard, Arthur C

    1994-01-01

    Newly developed semiconductor microstructures can now guide light and electrons resulting in important consequences for state-of-the-art electronic and photonic devices. This volume introduces a new generation of epitaxial microstructures. Special emphasis has been given to atomic control during growth and the interrelationship between the atomic arrangements and the properties of the structures.Key Features* Atomic-level control of semiconductor microstructures* Molecular beam epitaxy, metal-organic chemical vapor deposition* Quantum wells and quantum wires* Lasers, photon(IR)detectors, heterostructure transistors

  5. Introduction to semiconductor manufacturing technology

    CERN Document Server

    2012-01-01

    IC chip manufacturing processes, such as photolithography, etch, CVD, PVD, CMP, ion implantation, RTP, inspection, and metrology, are complex methods that draw upon many disciplines. [i]Introduction to Semiconductor Manufacturing Technologies, Second Edition[/i] thoroughly describes the complicated processes with minimal mathematics, chemistry, and physics; it covers advanced concepts while keeping the contents accessible to readers without advanced degrees. Designed as a textbook for college students, this book provides a realistic picture of the semiconductor industry and an in-depth discuss

  6. Wide gap semiconductor microwave devices

    International Nuclear Information System (INIS)

    Buniatyan, V V; Aroutiounian, V M

    2007-01-01

    A review of properties of wide gap semiconductor materials such as diamond, diamond-like carbon films, SiC, GaP, GaN and AlGaN/GaN that are relevant to electronic, optoelectronic and microwave applications is presented. We discuss the latest situation and perspectives based on experimental and theoretical results obtained for wide gap semiconductor devices. Parameters are taken from the literature and from some of our theoretical works. The correspondence between theoretical results and parameters of devices is critically analysed. (review article)

  7. Detection of radioactivity by semiconductors

    International Nuclear Information System (INIS)

    Anon.

    1991-01-01

    The class of detectors discussed in this chapter has a responsive component involving a diode, a junction between two types of semiconductor materials. Although diode detectors are not particularly efficient in counting radioactive emissions, they are superior to other commercially available detectors in spectroscopy. Consequently, diode detectors are used extensively for quanlitative purposes and for quantitative purposes when mixtures of radionuclides are present, not the usual situation with biological or medical research. Topics addressed in this chapter are as follows: Band Theory; Semiconductors and Junctions; and Radiation Detectors. 6 refs., 14 figs

  8. Modeling of semiconductor optical amplifiers

    DEFF Research Database (Denmark)

    Mørk, Jesper; Bischoff, Svend; Berg, Tommy Winther

    We discuss the modelling of semiconductor optical amplifiers with emphasis on their high-speed properties. Applications in linear amplification as well as ultrafast optical signal processing are reviewed. Finally, the possible role of quantum-dot based optical amplifiers is discussed.......We discuss the modelling of semiconductor optical amplifiers with emphasis on their high-speed properties. Applications in linear amplification as well as ultrafast optical signal processing are reviewed. Finally, the possible role of quantum-dot based optical amplifiers is discussed....

  9. Semiconductor X-ray spectrometers

    International Nuclear Information System (INIS)

    Muggleton, A.H.F.

    1978-02-01

    An outline is given of recent developments in particle and photon induced x-ray fluorescence (XRF) analysis. Following a brief description of the basic mechanism of semiconductor detector operation a comparison is made between semiconductor detectors, scintillators and gas filled proportional devices. Detector fabrication and cryostat design are described in more detail and the effects of various device parameters on system performance, such as energy resolution, count rate capability, efficiency, microphony, etc. are discussed. The main applications of these detectors in x-ray fluorescence analysis, electron microprobe analysis, medical and pollution studies are reviewed

  10. Integrating magnetism into semiconductor electronics

    Energy Technology Data Exchange (ETDEWEB)

    Zakharchenya, Boris P; Korenev, Vladimir L [A.F. Ioffe Physico-Technical Institute, Russian Academy of Sciences, St. Petersburg (Russian Federation)

    2005-06-30

    The view of a ferromagnetic-semiconducting hybrid structure as a single tunable system is presented. Based on an analysis of existing experiments it is shown that, contrary to a 'common sense', a nonmagnetic semiconductor is capable of playing an important role in controlling ferromagnetism. Magnetic properties of a hybrid (the hysteresis loop and the spatial orientation of magnetization) can be tuned both optically and electrically by utilizing semiconductor-making the hybrid an electronic-write-in and electronic-read-out elementary storage unit. (methodological notes)

  11. Integrating magnetism into semiconductor electronics

    International Nuclear Information System (INIS)

    Zakharchenya, Boris P; Korenev, Vladimir L

    2005-01-01

    The view of a ferromagnetic-semiconducting hybrid structure as a single tunable system is presented. Based on an analysis of existing experiments it is shown that, contrary to a 'common sense', a nonmagnetic semiconductor is capable of playing an important role in controlling ferromagnetism. Magnetic properties of a hybrid (the hysteresis loop and the spatial orientation of magnetization) can be tuned both optically and electrically by utilizing semiconductor-making the hybrid an electronic-write-in and electronic-read-out elementary storage unit. (methodological notes)

  12. Semiconductor lasers and herterojunction leds

    CERN Document Server

    Kressel, Henry

    2012-01-01

    Semiconductor Lasers and Heterojunction LEDs presents an introduction to the subject of semiconductor lasers and heterojunction LEDs. The book reviews relevant basic solid-state and electromagnetic principles; the relevant concepts in solid state physics; and the p-n junctions and heterojunctions. The text also describes stimulated emission and gain; the relevant concepts in electromagnetic field theory; and the modes in laser structures. The relation between electrical and optical properties of laser diodes; epitaxial technology; binary III-V compounds; and diode fabrication are also consider

  13. Quasi-adiabatic Switching for Metal-Island Quantum-dot Cellular Automata

    OpenAIRE

    Toth, Geza; Lent, Craig S.

    2000-01-01

    Recent experiments have demonstrated a working cell suitable for implementing the Quantum-dot Cellular Automata (QCA) paradigm. These experiments have been performed using metal island clusters. The most promising approach to QCA operation involves quasi-adiabatically switching the cells. This has been analyzed extensively in gated semiconductor cells. Here we present a metal island cell structure that makes quasi-adiabatic switching possible. We show how this permits quasi-adiabatic clocking...

  14. Diomede Islands, Bering Straight

    Science.gov (United States)

    2008-01-01

    The Diomede Islands consisting of the western island Big Diomede (also known as Imaqliq, Nunarbuk or Ratmanov Island), and the eastern island Little Diomede (also known as Krusenstern Island or Inaliq), are two rocky islands located in the middle of the Bering Strait between Russia and Alaska. The islands are separated by an international border and the International Date Line which is approximately 1.5 km from each island; you can look from Alaska into tomorrow in Russia. At the closest land approach between the United States, which controls Little Diomede, and Russia, which controls Big Diomede, they are 3 km apart. Little Diomede Island constitutes the Alaskan City of Diomede, while Big Diomede Island is Russia's easternmost point. The first European to reach the islands was the Russian explorer Semyon Dezhnev in 1648. The text of the 1867 treaty finalizing the sale of Alaska uses the islands to designate the border between the two nations. The image was acquired July 8, 2000, covers an area of 13.5 x 10.8 km, and is located at 65.8 degrees north latitude, 169 degrees west longitude. The U.S. science team is located at NASA's Jet Propulsion Laboratory, Pasadena, Calif. The Terra mission is part of NASA's Science Mission Directorate.

  15. Tales of island tails

    NARCIS (Netherlands)

    Groot, de Alma V.; Oost, Albert P.; Veeneklaas, Roos M.; Lammerts, Evert Jan; Duin, van Willem E.; Wesenbeeck, van Bregje K.

    2016-01-01

    The Frisian islands (Southern North Sea) have extensive island tails, i.e. the entire downdrift side of an island consisting of salt marshes, dunes, beaches and beach plains, and green beaches. Currently, large parts of these tails are ageing and losing dynamics, partly due to human influence.

  16. Rhode Island unemployment

    OpenAIRE

    Leonard Lardaro

    2010-01-01

    How can a state like Rhode Island have such a high unemployment rate? This question has been asked often over the past year, especially since at one point, Rhode Island found itself with the dubious distinction of having the highest unemployment rate in the United States. Following that extreme, Rhode Island seemed to settle into a niche where its rank was third nationally.

  17. Zirconates heteroepitaxy on silicon

    Science.gov (United States)

    Fompeyrine, Jean; Seo, Jin Won; Seigwart, Heinz; Rossel, Christophe; Locquet, Jean-Pierre

    2002-03-01

    In the coming years, agressive scaling in CMOS technology will probably trigger the transition to more advanced materials, for example alternate gate dielectrics. Epitaxial thin films are attractive candidates, as long as the difficult chemical and structural issues can be solved, and superior properties can be obtained. Since very few binary oxides can match the electrical, physical and structural requirements which are needed, a combination of those binaries are used here to investigate other lattice matched oxides. We will report on the growth of crystalline zirconium oxide thin films stabilized with different cationic substitutions. All films have been grown in an oxide-MBE system by direct evaporation of the elements on silicon substrates and exposure to molecular or atomic oxygen. The conditions required to obtain epitaxial thin films will be discussed, and successful examples will be presented.

  18. Waveguide based external cavity semiconductor lasers

    NARCIS (Netherlands)

    Oldenbeuving, Ruud; Klein, E.J.; Offerhaus, Herman L.; Lee, Christopher James; Verhaegen, M.; Boller, Klaus J.

    2012-01-01

    We report on progress of the project waveguide based external cavity semiconductor laser (WECSL) arrays. Here we present the latest results on our efforts to mode lock an array of tunable, external cavity semiconductor lasers.

  19. Influence of phonons on semiconductor quantum emission

    Energy Technology Data Exchange (ETDEWEB)

    Feldtmann, Thomas

    2009-07-06

    A microscopic theory of interacting charge carriers, lattice vibrations, and light modes in semiconductor systems is presented. The theory is applied to study quantum dots and phonon-assisted luminescence in bulk semiconductors and heterostructures. (orig.)

  20. 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.

  1. 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.

  2. Nuclear radiation detection by a variband semiconductor

    International Nuclear Information System (INIS)

    Volkov, A.S.

    1981-01-01

    Possibilities of using a variband semiconductor for detecting nuclear radiations are considered. It is shown that the variaband quasielectric field effectively collects charges induced by a nuclear particle only at a small mean free path in the semiconductor (up to 100 μm), the luminescence spectrum of the variband semiconductor when a nuclear particle gets into it, in principle, permits to determine both the energy and mean free path in the semiconductor (even at large mean free paths) [ru

  3. Ultrafast THz Saturable Absorption in Doped Semiconductors

    DEFF Research Database (Denmark)

    Turchinovich, Dmitry; Hoffmann, Matthias C.

    2011-01-01

    We demonstrate ultrafast THz saturable absorption in n-doped semiconductors by nonlinear THz time-domain spectroscopy. This effect is caused by the semiconductor conductivity modulation due to electron heating and satellite-valley scattering in strong THz fields.......We demonstrate ultrafast THz saturable absorption in n-doped semiconductors by nonlinear THz time-domain spectroscopy. This effect is caused by the semiconductor conductivity modulation due to electron heating and satellite-valley scattering in strong THz fields....

  4. Laser semiconductor diode integrated with frequency doubler

    International Nuclear Information System (INIS)

    Tighineanu, I.; Dorogan, V.; Suruceanu, G.

    2003-01-01

    The invention relates to the technology of optoelectronic semiconductor devices and may be used in the production of laser semiconductor diodes integrated with optical nonlinear elements. The laser semiconductor diode integrated with frequency doubler includes a semiconductor substrate, a laser structure with waveguide. metal contacts in the waveguide of the laser structure it is formed a nanostructured field so that the nanostructure provides for the fulfillment of the phase synchronism conditions

  5. Diode having trenches in a semiconductor region

    Energy Technology Data Exchange (ETDEWEB)

    Palacios, Tomas Apostol; Lu, Bin; Matioli, Elison de Nazareth

    2016-03-22

    An electrode structure is described in which conductive regions are recessed into a semiconductor region. Trenches may be formed in a semiconductor region, such that conductive regions can be formed in the trenches. The electrode structure may be used in semiconductor devices such as field effect transistors or diodes. Nitride-based power semiconductor devices are described including such an electrode structure, which can reduce leakage current and otherwise improve performance.

  6. Semiconductor nanostructures for infrared applications

    NARCIS (Netherlands)

    Zurauskiene, N.; Asmontas, S.; Dargys, A.; Kundrotas, J.; Janssen, G.; Goovaerts, E.; Marcinkevicius, S.; Koenraad, P.M.; Wolter, J.H.; Leon, R.

    2004-01-01

    We present the results of time-resolved photoluminescence (TRPL) and optically detected microwave resonance (ODMR) spectroscopy investigations of semiconductor quantum dots and quantum wells. The ODMR spectra of InAs/GaAs QDs were detected via modulation of the total intensity of the QDs emission

  7. A Brief History of ... Semiconductors

    Science.gov (United States)

    Jenkins, Tudor

    2005-01-01

    The development of studies in semiconductor materials is traced from its beginnings with Michael Faraday in 1833 to the production of the first silicon transistor in 1954, which heralded the age of silicon electronics and microelectronics. Prior to the advent of band theory, work was patchy and driven by needs of technology. However, the arrival…

  8. Semiconductor radiation detectors: device physics

    National Research Council Canada - National Science Library

    Lutz, Gerhard

    1999-01-01

    ..., including nuclear physics, elementary particle physics, optical and x-ray astronomy, medicine, and materials testing - and the number of applications is growing continually. Closely related, and initiated by the application of semiconductors, is the development of low-noise low-power integrated electronics for signal readout. The success of semicond...

  9. Towards filament free semiconductor lasers

    DEFF Research Database (Denmark)

    McInerney, John; O'Brien, Peter; Skovgaard, Peter M. W.

    2000-01-01

    We outline physical models and simulations for suppression of self-focusing and filamentation in large aperture semiconductor lasers. The principal technical objective is to generate multi-watt CW or quasi-CW outputs with nearly diffraction limited beams, suitable for long distance free space...... propagation structures in lasers and amplifiers which suppress lateral reflections....

  10. Ultrafast Spectroscopy of Semiconductor Devices

    DEFF Research Database (Denmark)

    Borri, Paola; Langbein, Wolfgang; Hvam, Jørn Marcher

    1999-01-01

    In this work we present an experimental technique for investigating ultrafast carrier dynamics in semiconductor optical amplifiers at room temperature. These dynamics, influenced by carrier heating, spectral hole-burning and two-photon absorption, are very important for device applications in inf...

  11. Radiation damage in semiconductor detectors

    International Nuclear Information System (INIS)

    Kraner, H.W.

    1981-12-01

    A survey is presented of the important damage-producing interactions in semiconductor detectors and estimates of defect numbers are made for MeV protons, neutrons and electrons. Damage effects of fast neutrons in germanium gamma ray spectrometers are given in some detail. General effects in silicon detectors are discussed and damage constants and their relationship to leakage current is introduced

  12. Nanoscale “Quantum” Islands on Metal Substrates: Microscopy Studies and Electronic Structure Analyses

    Directory of Open Access Journals (Sweden)

    Da-Jiang Liu

    2010-07-01

    Full Text Available Confinement of electrons can occur in metal islands or in continuous films grown heteroepitaxially upon a substrate of a different metal or on a metallic alloy. Associated quantum size effects (QSE can produce a significant height-dependence of the surface free energy for nanoscale thicknesses of up to 10–20 layers. This may suffice to induce height selection during film growth. Scanning STM analysis has revealed remarkable flat-topped or mesa-like island and film morphologies in various systems. We discuss in detail observations of QSE and associated film growth behavior for Pb/Cu(111, Ag/Fe(100, and Cu/fcc-Fe/Cu(100 [A/B or A/B/A], and for Ag/NiAl(110 with brief comments offered for Fe/Cu3Au(001 [A/BC binary alloys]. We also describe these issues for Ag/5-fold i-Al-Pd-Mn and Bi/5-fold i-Al-Cu-Fe [A/BCD ternary icosohedral quasicrystals]. Electronic structure theory analysis, either at the level of simple free electron gas models or more sophisticated Density Functional Theory calculations, can provide insight into the QSE-mediated thermodynamic driving force underlying height selection.

  13. Transient photoconductivity in amorphous semiconductors

    International Nuclear Information System (INIS)

    Mpawenayo, P.

    1997-07-01

    Localized states in amorphous semiconductors are divided in disorder induced shallow trap levels and dangling bonds deep states. Dangling bonds are assumed here to be either neutral or charged and their energy distribution is a single gaussian. Here, it is shown analytically that transient photocurrent in amorphous semiconductors is fully controlled by charge carriers transitions between localized states for one part and tunneling hopping carriers on the other. Localized dangling bonds deep states act as non radiative recombination centres, while hopping tunnelling is assisted by the Coulomb interaction between defects sites. The half-width of defects distribution is the disorder parameter that determines the carrier hopping time between defects sites. The macroscopic time that explains the long decay response times observed will all types of amorphous semiconductors is duly thought to be temperature dependent. Basic equations developed by Longeaud and Kleider are solved for the general case of a semiconductor after photo-generation. It turns out that the transient photoconductivity decay has two components; one with short response times from carriers trap-release transitions between shallow levels and extended states and a hopping component made of inter-dependent exponentials whose time constants span in larger ranges depending on disorder. The photoconductivity hopping component appears as an additional term to be added to photocurrents derived from existing models. The results of the present study explain and complete the power law decay derived in the multiple trapping models developed 20 years ago only in the approximation of the short response time regime. The long response time regime is described by the hopping macroscopic time. The present model is verified for all samples of amorphous semiconductors known so far. Finally, it is proposed to improved the modulated photoconductivity calculation techniques by including the long-lasting hopping dark documents

  14. Delayed plastic relaxation limit in SiGe islands grown by Ge diffusion from a local source

    Energy Technology Data Exchange (ETDEWEB)

    Vanacore, G. M.; Zani, M.; Tagliaferri, A., E-mail: alberto.tagliaferri@polimi.it [CNISM-Dipartimento di Fisica, Politecnico di Milano, Piazza Leonardo da Vinci 32, I-20133 Milano (Italy); Nicotra, G. [IMM-CNR, Stradale Primosole 50, I-95121 Catania (Italy); Bollani, M. [CNR-IFN, LNESS, Via Anzani 42, I-22100 Como (Italy); Bonera, E.; Montalenti, F.; Picco, A.; Boioli, F. [Dipartimento di Scienza dei Materiali and L-NESS, Università Milano-Bicocca, via Cozzi 53, I-20125 Milano (Italy); Capellini, G. [Department of Sciences at the Università Roma Tre, Via Vasca Navale 79, 00146 Roma (Italy); Isella, G. [CNISM, LNESS, Dipartimento di Fisica, Politecnico di Milano (Polo di Como), Via Anzani 42, I-22100 Como (Italy); Osmond, J. [ICFO–The Institute of Photonic Sciences, Av. Carl Friedrich Gauss, 3, E-08860 Castelldefels (Barcelona) (Spain)

    2015-03-14

    The hetero-epitaxial strain relaxation in nano-scale systems plays a fundamental role in shaping their properties. Here, the elastic and plastic relaxation of self-assembled SiGe islands grown by surface-thermal-diffusion from a local Ge solid source on Si(100) are studied by atomic force and transmission electron microscopies, enabling the simultaneous investigation of the strain relaxation in different dynamical regimes. Islands grown by this technique remain dislocation-free and preserve a structural coherence with the substrate for a base width as large as 350 nm. The results indicate that a delay of the plastic relaxation is promoted by an enhanced Si-Ge intermixing, induced by the surface-thermal-diffusion, which takes place already in the SiGe overlayer before the formation of a critical nucleus. The local entropy of mixing dominates, leading the system toward a thermodynamic equilibrium, where non-dislocated, shallow islands with a low residual stress are energetically stable. These findings elucidate the role of the interface dynamics in modulating the lattice distortion at the nano-scale, and highlight the potential use of our growth strategy to create composition and strain-controlled nano-structures for new-generation devices.

  15. Fermi level dependent native defect formation: Consequences for metal-semiconductor and semiconductor-semiconductor interfaces

    International Nuclear Information System (INIS)

    Walukiewicz, W.

    1988-02-01

    The amphoteric native defect model of the Schottky barrier formation is used to analyze the Fermi level pinning at metal/semiconductor interfaces for submonolayer metal coverages. It is assumed that the energy required for defect generation is released in the process of surface back-relaxation. Model calculations for metal/GaAs interfaces show a weak dependence of the Fermi level pinning on the thickness of metal deposited at room temperature. This weak dependence indicates a strong dependence of the defect formation energy on the Fermi level, a unique feature of amphoteric native defects. This result is in very good agreement with experimental data. It is shown that a very distinct asymmetry in the Fermi level pinning on p- and n-type GaAs observed at liquid nitrogen temperatures can be understood in terms of much different recombination rates for amphoteric native defects in those two types of materials. Also, it is demonstrated that the Fermi level stabilization energy, a central concept of the amphoteric defect system, plays a fundamental role in other phenomena in semiconductors such as semiconductor/semiconductor heterointerface intermixing and saturation of free carrier concentration. 33 refs., 6 figs

  16. Optoelectronic device physics and technology of nitride semiconductors from the UV to the terahertz

    Science.gov (United States)

    Moustakas, Theodore D.; Paiella, Roberto

    2017-10-01

    This paper reviews the device physics and technology of optoelectronic devices based on semiconductors of the GaN family, operating in the spectral regions from deep UV to Terahertz. Such devices include LEDs, lasers, detectors, electroabsorption modulators and devices based on intersubband transitions in AlGaN quantum wells (QWs). After a brief history of the development of the field, we describe how the unique crystal structure, chemical bonding, and resulting spontaneous and piezoelectric polarizations in heterostructures affect the design, fabrication and performance of devices based on these materials. The heteroepitaxial growth and the formation and role of extended defects are addressed. The role of the chemical bonding in the formation of metallic contacts to this class of materials is also addressed. A detailed discussion is then presented on potential origins of the high performance of blue LEDs and poorer performance of green LEDs (green gap), as well as of the efficiency reduction of both blue and green LEDs at high injection current (efficiency droop). The relatively poor performance of deep-UV LEDs based on AlGaN alloys and methods to address the materials issues responsible are similarly addressed. Other devices whose state-of-the-art performance and materials-related issues are reviewed include violet-blue lasers, ‘visible blind’ and ‘solar blind’ detectors based on photoconductive and photovoltaic designs, and electroabsorption modulators based on bulk GaN or GaN/AlGaN QWs. Finally, we describe the basic physics of intersubband transitions in AlGaN QWs, and their applications to near-infrared and terahertz devices.

  17. Paradise Islands? Island States and Environmental Performance

    Directory of Open Access Journals (Sweden)

    Sverker C. Jagers

    2016-03-01

    Full Text Available Island states have been shown to outperform continental states on a number of large-scale coordination-related outcomes, such as levels of democracy and institutional quality. The argument developed and tested in this article contends that the same kind of logic may apply to islands’ environmental performance, too. However, the empirical analysis shows mixed results. Among the 105 environmental outcomes that we analyzed, being an island only has a positive impact on 20 of them. For example, island states tend to outcompete continental states with respect to several indicators related to water quality but not in aspects related to biodiversity, protected areas, or environmental regulations. In addition, the causal factors previously suggested to make islands outperform continental states in terms of coordination have weak explanatory power in predicting islands’ environmental performance. We conclude the paper by discussing how these interesting findings can be further explored.

  18. Semiconductor detectors in nuclear and particle physics

    International Nuclear Information System (INIS)

    Rehak, P.; Gatti, E.

    1992-01-01

    Semiconductor detectors for elementary particle physics and nuclear physics in the energy range above 1 GeV are briefly reviewed. In these two fields semiconductor detectors are used mainly for the precise position sensing. In a typical experiment, the position of a fast charged particle crossing a relatively thin semiconductor detector is measured. The position resolution achievable by semiconductor detectors is compared with the resolution achievable by gas filled position sensing detectors. Semiconductor detectors are divided into two groups: Classical semiconductor diode detectors and semiconductor memory detectors. Principles of the signal formation and the signal read-out for both groups of detectors are described. New developments of silicon detectors of both groups are reported

  19. Semiconductor detectors in nuclear and particle physics

    International Nuclear Information System (INIS)

    Rehak, P.; Gatti, E.

    1995-01-01

    Semiconductor detectors for elementary particle physics and nuclear physics in the energy range above 1 GeV are briefly reviewed. In these two fields semiconductor detectors are used mainly for the precise position sensing. In a typical experiment, the position of a fast charged particle crossing a relatively thin semiconductor detector is measured. The position resolution achievable by semiconductor detectors is compared with the resolution achievable by gas filled position sensing detectors. Semiconductor detectors are divided into two groups; (i) classical semiconductor diode detectors and (ii) semiconductor memory detectors. Principles of the signal formation and the signal read-out for both groups of detectors are described. New developments of silicon detectors of both groups are reported. copyright 1995 American Institute of Physics

  20. Transversal light forces in semiconductors

    CERN Document Server

    Lindberg, M

    2003-01-01

    The transversal light force is a well established effect in atomic and molecular systems that are exposed to spatially inhomogeneous light fields. In this paper it is shown theoretically that in an excited semiconductor, containing an electron-hole plasma or excitons, a similar light force exists, if the semiconductor is exposed to an ultrashort spatially inhomogeneous light field. The analysis is based on the equations of motion for the Wigner distribution functions of charge carrier populations and interband polarizations. The results show that, while the light force on the electron-hole plasma or the excitons does exist, its effects on the kinetic behaviour of the electron-hole plasma or the excitons are different compared to the situation in an atomic or molecular system. A detailed analysis presented here traces this difference back to the principal differences between atoms and molecules on the one hand and electron-hole plasmas or excitons on the other hand.

  1. Semiconductor electrolyte photovoltaic energy converter

    Science.gov (United States)

    Anderson, W. W.; Anderson, L. B.

    1975-01-01

    Feasibility and practicality of a solar cell consisting of a semiconductor surface in contact with an electrolyte are evaluated. Basic components and processes are detailed for photovoltaic energy conversion at the surface of an n-type semiconductor in contact with an electrolyte which is oxidizing to conduction band electrons. Characteristics of single crystal CdS, GaAs, CdSe, CdTe and thin film CdS in contact with aqueous and methanol based electrolytes are studied and open circuit voltages are measured from Mott-Schottky plots and open circuit photo voltages. Quantum efficiencies for short circuit photo currents of a CdS crystal and a 20 micrometer film are shown together with electrical and photovoltaic properties. Highest photon irradiances are observed with the GaAs cell.

  2. Hypersonic modes in nanophononic semiconductors.

    Science.gov (United States)

    Hepplestone, S P; Srivastava, G P

    2008-09-05

    Frequency gaps and negative group velocities of hypersonic phonon modes in periodically arranged composite semiconductors are presented. Trends and criteria for phononic gaps are discussed using a variety of atomic-level theoretical approaches. From our calculations, the possibility of achieving semiconductor-based one-dimensional phononic structures is established. We present results of the location and size of gaps, as well as negative group velocities of phonon modes in such structures. In addition to reproducing the results of recent measurements of the locations of the band gaps in the nanosized Si/Si{0.4}Ge{0.6} superlattice, we show that such a system is a true one-dimensional hypersonic phononic crystal.

  3. Dielectric function of semiconductor superlattice

    International Nuclear Information System (INIS)

    Qin Guoyi.

    1990-08-01

    We present a calculation of the dielectric function for semiconductor GaAs/Ga 1-x Al x As superlattice taking account of the extension of the electron envelope function and the difference of both the dielectric constant and width between GaAs and Ga 1-x Al x As layers. In the appropriate limits, our results exactly reduce to the well-known results of the quasi two-dimensional electron gas obtained by Lee and Spector and of the period array of two-dimensional electron layers obtained by Das Sarma and Quinn. By means of the dielectric function of the superlattice, the dispersion relation of the collective excitation and the screening property of semiconductor superlattice are discussed and compared with the results of the quasi two-dimensional system and with the results of the periodic array of the two-dimensional electron layers. (author). 4 refs, 3 figs

  4. Spectroscopic analysis of optoelectronic semiconductors

    CERN Document Server

    Jimenez, Juan

    2016-01-01

    This book deals with standard spectroscopic techniques which can be used to analyze semiconductor samples or devices, in both, bulk, micrometer and submicrometer scale. The book aims helping experimental physicists and engineers to choose the right analytical spectroscopic technique in order to get specific information about their specific demands. For this purpose, the techniques including technical details such as apparatus and probed sample region are described. More important, also the expected outcome from experiments is provided. This involves also the link to theory, that is not subject of this book, and the link to current experimental results in the literature which are presented in a review-like style. Many special spectroscopic techniques are introduced and their relationship to the standard techniques is revealed. Thus the book works also as a type of guide or reference book for people researching in optical spectroscopy of semiconductors.

  5. Efficient Spin Injection into Semiconductor

    International Nuclear Information System (INIS)

    Nahid, M.A.I.

    2010-06-01

    Spintronic research has made tremendous progress nowadays for making future devices obtain extra advantages of low power, and faster and higher scalability compared to present electronic devices. A spintronic device is based on the transport of an electron's spin instead of charge. Efficient spin injection is one of the very important requirements for future spintronic devices. However, the effective spin injection is an exceedingly difficult task. In this paper, the importance of spin injection, basics of spin current and the essential requirements of spin injection are illustrated. The experimental technique of electrical spin injection into semiconductor is also discussed based on the experimental experience. The electrical spin injection can easily be implemented for spin injection into any semiconductor. (author)

  6. Compound semiconductor optical waveguide switch

    Science.gov (United States)

    Spahn, Olga B.; Sullivan, Charles T.; Garcia, Ernest J.

    2003-06-10

    An optical waveguide switch is disclosed which is formed from III-V compound semiconductors and which has a moveable optical waveguide with a cantilevered portion that can be bent laterally by an integral electrostatic actuator to route an optical signal (i.e. light) between the moveable optical waveguide and one of a plurality of fixed optical waveguides. A plurality of optical waveguide switches can be formed on a common substrate and interconnected to form an optical switching network.

  7. Semiconductors put spin in spintronics

    International Nuclear Information System (INIS)

    Weiss, Dieter

    2000-01-01

    Electrons and holes, which carry the current in semiconductor devices, are quantum-mechanical objects characterized by a set of quantum numbers - the band index, the wave-vector (which is closely related to the electron or hole velocity) and spin. The spin, however, is one of the strangest properties of particles. In simple terms, we can think of the spin as an internal rotation of the electron, but it has no classical counterpart. The spin is connected to a quantized magnetic moment and hence acts as a microscopic magnet. Thus the electron spin can adopt one of two directions (''up'' or ''down'') in a magnetic field. The spin plays no role in conventional electronics and the current in any semiconductor device is made up of a mixture of electrons with randomly oriented spins. However, a new range of electronic devices that transport the spin of the electrons, in addition to their charge, is being developed. But the biggest obstacle to making practical ''spin electronic'' or ''spintronic'' devices so far has been finding a way of injecting spin-polarized electrons or holes into the semiconductor and then detecting them. Recently a team of physicists from the University of Wuerzburg in Germany, and also a collaboration of researchers from Tohoku University in Japan and the University of California at Santa Barbara, have found a way round these problems using either semi-magnetic or ferromagnetic semiconductors as ''spin aligners'' (R Fiederling et al. 1999 Nature 402 787; Y Ohno et al. 1999 Nature 402 790). In this article the author presents the latest breakthrough in spintronics research. (UK)

  8. Room-temperature heteroepitaxy of single-phase Al1−xInxN films with full composition range on isostructural wurtzite templates

    International Nuclear Information System (INIS)

    Hsiao, Ching-Lien; Palisaitis, Justinas; Junaid, Muhammad; Persson, Per O.Å.; Jensen, Jens; Zhao, Qing-Xiang; Hultman, Lars; Chen, Li-Chyong; Chen, Kuei-Hsien; Birch, Jens

    2012-01-01

    Al 1−x In x N heteroepitaxial layers covering the full composition range have been realized by magnetron sputter epitaxy on basal-plane AlN, GaN, and ZnO templates at room temperature (RT). Both Al 1−x In x N single layers and multilayers grown on these isostructural templates show single phase, single crystal wurtzite structure. Even at large lattice mismatch between the film and the template, for instance InN/AlN (∼ 13% mismatch), heteroepitaxy is achieved. However, RT-grown Al 1−x In x N films directly deposited on non-isostructural c-plane sapphire substrate exhibit a polycrystalline structure for all compositions, suggesting that substrate surface structure is important for guiding the initial nucleation. Degradation of Al 1−x In x N structural quality with increasing indium content is attributed to the formation of more point- and structural defects. The defects result in a prominent hydrostatic tensile stress component, in addition to the biaxial stress component introduced by lattice mismatch, in all RT-grown Al 1−x In x N films. These effects are reflected in the measured in-plane and out-of-plane strains. The effect of hydrostatic stress is negligible compared to the effects of lattice mismatch in high-temperature grown AlN layers thanks to their low amount of defects. We found that Vegard’s rule is applicable to determine x in the RT-grown Al 1−x In x N epilayers if the lattice constants of RT-sputtered AlN and InN films are used instead of those of the strain-free bulk materials. - Highlights: ► Magnetron sputter epitaxy of single-phase Al 1−x In x N(0001) at room temperature ► Growing Al 1−x In x N onto temperature sensitive substrates is desirable. ► Substrate surface structure plays a vital role at nucleation stage. ► Point and extended defects produce hydrostatic tensile stress. ► The applicability of Vegard's rule for these compounds is confirmed.

  9. Dry etching technology for semiconductors

    CERN Document Server

    Nojiri, Kazuo

    2015-01-01

    This book is a must-have reference to dry etching technology for semiconductors, which will enable engineers to develop new etching processes for further miniaturization and integration of semiconductor integrated circuits.  The author describes the device manufacturing flow, and explains in which part of the flow dry etching is actually used. The content is designed as a practical guide for engineers working at chip makers, equipment suppliers and materials suppliers, and university students studying plasma, focusing on the topics they need most, such as detailed etching processes for each material (Si, SiO2, Metal etc) used in semiconductor devices, etching equipment used in manufacturing fabs, explanation of why a particular plasma source and gas chemistry are used for the etching of each material, and how to develop etching processes.  The latest, key technologies are also described, such as 3D IC Etching, Dual Damascene Etching, Low-k Etching, Hi-k/Metal Gate Etching, FinFET Etching, Double Patterning ...

  10. Ballistic superconductivity in semiconductor nanowires

    Science.gov (United States)

    Zhang, Hao; Gül, Önder; Conesa-Boj, Sonia; Nowak, Michał P.; Wimmer, Michael; Zuo, Kun; Mourik, Vincent; de Vries, Folkert K.; van Veen, Jasper; de Moor, Michiel W. A.; Bommer, Jouri D. S.; van Woerkom, David J.; Car, Diana; Plissard, Sébastien R; Bakkers, Erik P.A.M.; Quintero-Pérez, Marina; Cassidy, Maja C.; Koelling, Sebastian; Goswami, Srijit; Watanabe, Kenji; Taniguchi, Takashi; Kouwenhoven, Leo P.

    2017-01-01

    Semiconductor nanowires have opened new research avenues in quantum transport owing to their confined geometry and electrostatic tunability. They have offered an exceptional testbed for superconductivity, leading to the realization of hybrid systems combining the macroscopic quantum properties of superconductors with the possibility to control charges down to a single electron. These advances brought semiconductor nanowires to the forefront of efforts to realize topological superconductivity and Majorana modes. A prime challenge to benefit from the topological properties of Majoranas is to reduce the disorder in hybrid nanowire devices. Here we show ballistic superconductivity in InSb semiconductor nanowires. Our structural and chemical analyses demonstrate a high-quality interface between the nanowire and a NbTiN superconductor that enables ballistic transport. This is manifested by a quantized conductance for normal carriers, a strongly enhanced conductance for Andreev-reflecting carriers, and an induced hard gap with a significantly reduced density of states. These results pave the way for disorder-free Majorana devices. PMID:28681843

  11. Radiation tolerance of amorphous semiconductors

    International Nuclear Information System (INIS)

    Nicolaides, R.V.; DeFeo, S.; Doremus, L.W.

    1976-01-01

    In an attempt to determine the threshold radiation damage in amorphous semiconductors, radiation tests were performed on amorphous semiconductor thin film materials and on threshold and memory devices. The influence of flash x-rays and neutron radiation upon the switching voltages, on- and off-state characteristics, dielectric response, optical transmission, absorption band edge and photoconductivity were measured prior to, during and following irradiation. These extensive tests showed the high radiation tolerance of amorphous semiconductor materials. Electrical and optical properties, other than photoconductivity, have a neutron radiation tolerance threshold above 10 17 nvt in the steady state and 10 14 nvt in short (50 μsec to 16 msec) pulses. Photoconductivity increases by 1 1 / 2 orders of magnitude at the level of 10 14 nvt (short pulses of 50 μsec). Super flash x-rays up to 5000 rads (Si), 20 nsec, do not initiate switching in off-state samples which are voltage biased up to 90 percent of the threshold voltage. Both memory and threshold amorphous devices are capable of switching on and off during nuclear radiation transients at least as high as 2 x 10 14 nvt in 50 μsec pulses

  12. Thienoacene-based organic semiconductors.

    Science.gov (United States)

    Takimiya, Kazuo; Shinamura, Shoji; Osaka, Itaru; Miyazaki, Eigo

    2011-10-11

    Thienoacenes consist of fused thiophene rings in a ladder-type molecular structure and have been intensively studied as potential organic semiconductors for organic field-effect transistors (OFETs) in the last decade. They are reviewed here. Despite their simple and similar molecular structures, the hitherto reported properties of thienoacene-based OFETs are rather diverse. This Review focuses on four classes of thienoacenes, which are classified in terms of their chemical structures, and elucidates the molecular electronic structure of each class. The packing structures of thienoacenes and the thus-estimated solid-state electronic structures are correlated to their carrier transport properties in OFET devices. With this perspective of the molecular structures of thienoacenes and their carrier transport properties in OFET devices, the structure-property relationships in thienoacene-based organic semiconductors are discussed. The discussion provides insight into new molecular design strategies for the development of superior organic semiconductors. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Identification of defects in semiconductors

    CERN Document Server

    Stavola, Michael; Weber, Eicke R; Stavola, Michael

    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 traditi...

  14. The Electrical Characteristics of The N-Organic Semiconductor/P-Inorganic Semiconductor Diode

    International Nuclear Information System (INIS)

    Aydin, M. E.

    2008-01-01

    n-organic semiconductor (PEDOT) / p-inorganic semiconductor Si diode was formed by deep coating method. The method has been achieved by coating n-inorganic semiconductor PEDOT on top of p-inorganic semiconductor. The n-organic semiconductor PEDOT/ p-inorganic semiconductor diode demonstrated rectifying behavior by the current-voltage (I-V) curves studied at room temperature. The barrier height , ideality factor values were obtained as of 0.88 eV and 1.95 respectively. The diode showed non-ideal I-V behavior with an ideality factor greater than unity that could be ascribed to the interfacial layer

  15. Tanzania - Mafia Island Airport

    Data.gov (United States)

    Millennium Challenge Corporation — The evaluation design and subsequent data gathering activities will address the following key research questions: a) Has the Mafia Island Airport Upgrade Project...

  16. New Icosahedral Boron Carbide Semiconductors

    Science.gov (United States)

    Echeverria Mora, Elena Maria

    Novel semiconductor boron carbide films and boron carbide films doped with aromatic compounds have been investigated and characterized. Most of these semiconductors were formed by plasma enhanced chemical vapor deposition. The aromatic compound additives used, in this thesis, were pyridine (Py), aniline, and diaminobenzene (DAB). As one of the key parameters for semiconducting device functionality is the metal contact and, therefore, the chemical interactions or band bending that may occur at the metal/semiconductor interface, X-ray photoemission spectroscopy has been used to investigate the interaction of gold (Au) with these novel boron carbide-based semiconductors. Both n- and p-type films have been tested and pure boron carbide devices are compared to those containing aromatic compounds. The results show that boron carbide seems to behave differently from other semiconductors, opening a way for new analysis and approaches in device's functionality. By studying the electrical and optical properties of these films, it has been found that samples containing the aromatic compound exhibit an improvement in the electron-hole separation and charge extraction, as well as a decrease in the band gap. The hole carrier lifetimes for each sample were extracted from the capacitance-voltage, C(V), and current-voltage, I(V), curves. Additionally, devices, with boron carbide with the addition of pyridine, exhibited better collection of neutron capture generated pulses at ZERO applied bias, compared to the pure boron carbide samples. This is consistent with the longer carrier lifetimes estimated for these films. The I-V curves, as a function of external magnetic field, of the pure boron carbide films and films containing DAB demonstrate that significant room temperature negative magneto-resistance (> 100% for pure samples, and > 50% for samples containing DAB) is possible in the resulting dielectric thin films. Inclusion of DAB is not essential for significant negative magneto

  17. Conductivity in transparent oxide semiconductors.

    Science.gov (United States)

    King, P D C; Veal, T D

    2011-08-24

    Despite an extensive research effort for over 60 years, an understanding of the origins of conductivity in wide band gap transparent conducting oxide (TCO) semiconductors remains elusive. While TCOs have already found widespread use in device applications requiring a transparent contact, there are currently enormous efforts to (i) increase the conductivity of existing materials, (ii) identify suitable alternatives, and (iii) attempt to gain semiconductor-engineering levels of control over their carrier density, essential for the incorporation of TCOs into a new generation of multifunctional transparent electronic devices. These efforts, however, are dependent on a microscopic identification of the defects and impurities leading to the high unintentional carrier densities present in these materials. Here, we review recent developments towards such an understanding. While oxygen vacancies are commonly assumed to be the source of the conductivity, there is increasing evidence that this is not a sufficient mechanism to explain the total measured carrier concentrations. In fact, many studies suggest that oxygen vacancies are deep, rather than shallow, donors, and their abundance in as-grown material is also debated. We discuss other potential contributions to the conductivity in TCOs, including other native defects, their complexes, and in particular hydrogen impurities. Convincing theoretical and experimental evidence is presented for the donor nature of hydrogen across a range of TCO materials, and while its stability and the role of interstitial versus substitutional species are still somewhat open questions, it is one of the leading contenders for yielding unintentional conductivity in TCOs. We also review recent work indicating that the surfaces of TCOs can support very high carrier densities, opposite to the case for conventional semiconductors. In thin-film materials/devices and, in particular, nanostructures, the surface can have a large impact on the total

  18. Numerical studies of temperature profile and hydrodynamic phenomena during excimer laser assisted heteroepitaxial growth of patterned silicon and germanium bi-layers

    Energy Technology Data Exchange (ETDEWEB)

    Conde, J.C., E-mail: jconde@uvigo.e [Dpto. Fisica Aplicada, E.T.S.I.I. University of Vigo, Campus Universitario, Rua Maxwell s/n, E-36310 Vigo (Spain); Chiussi, S. [Dpto. Fisica Aplicada, E.T.S.I.I. University of Vigo, Campus Universitario, Rua Maxwell s/n, E-36310 Vigo (Spain); Martin, E. [Dpto. de Mecanica, Maquinas Motores Termicos y Fluidos, E.T.S.I.I. University of Vigo, Campus Universitario, Rua Maxwell s/n, E-36310 Vigo (Spain); Gontad, F. [Dpto. Fisica Aplicada, E.T.S.I.I. University of Vigo, Campus Universitario, Rua Maxwell s/n, E-36310 Vigo (Spain); Fornarini, L. [Enea-Frascati, Via Enrico Fermi 45, I-00044 Frascati Roma (Italy); Leon, B. [Dpto. Fisica Aplicada, E.T.S.I.I. University of Vigo, Campus Universitario, Rua Maxwell s/n, E-36310 Vigo (Spain)

    2010-01-01

    In this manuscript, a 3-D axisymmetric model for the heteroepitaxial growth induced by irradiating thin patterned amorphous hydrogenated silicon (a-Si:H) and germanium (a-Ge:H) bi-layers on Si (100) with pulsed UV-laser radiation, is presented. For reducing optimization steps, an efficient simulation of the laser induced processes that include rapid heating and solidification phenomena in the range of several tenth of nanoseconds, must be performed, if alloy composition and quality has to be adjusted. In this study, the effects of various laser energy densities on different amorphous Si/Ge bi-layer structures has been predicted and adjusted to obtain the desired Ge concentration profiles for applications as sacrificial layers, i.e. a Ge containing film buried under a Si rich surface layer. The numerical model includes the temperature dependent variations of the thermophysical properties and takes the coupled effects of temperature and hydrodynamic phenomena for a Boussinesq fluid, to estimate the element interdiffusion during the process and predicting the concentration profiles.

  19. Critical thickness and strain relaxation in high-misfit heteroepitaxial systems: PbTe1-xSex on PbSe (001)

    International Nuclear Information System (INIS)

    Wiesauer, Karin; Springholz, G.

    2004-01-01

    Strain relaxation and misfit dislocation formation is investigated for the high-misfit PbTe 1-x Se x /PbSe (001) heteroepitaxial system in which the lattice mismatch varies from 0% to 5.5%. Because a two-dimensional (2D) layer growth prevails for all PbTe 1-x Se x ternary compositions, the lattice mismatch is relaxed purely by misfit dislocations. In addition, it is found that strain relaxation is not hindered by dislocation kinetics. Therefore, this material combination is an ideal model system for testing the equilibrium Frank-van der Merwe and Matthews-Blakeslee strain relaxation models. In our experiments, we find significantly lower values of the critical layer thickness as compared to the model predictions. This discrepancy is caused by the inappropriate description of the dislocation self-energies when the layer thickness becomes comparable to the dislocation core radius. To resolve this problem, a modified expression for the dislocation self-energy is proposed. The resulting theoretical critical thicknesses are in excellent agreement with the experimental data. In addition, a remarkable universal scaling behavior is found for the strain relaxation data. This underlines the breakdown of the current strain relaxation models

  20. Ultralow threading dislocation density in GaN epilayer on near-strain-free GaN compliant buffer layer and its applications in hetero-epitaxial LEDs.

    Science.gov (United States)

    Shih, Huan-Yu; Shiojiri, Makoto; Chen, Ching-Hsiang; Yu, Sheng-Fu; Ko, Chung-Ting; Yang, Jer-Ren; Lin, Ray-Ming; Chen, Miin-Jang

    2015-09-02

    High threading dislocation (TD) density in GaN-based devices is a long unresolved problem because of the large lattice mismatch between GaN and the substrate, which causes a major obstacle for the further improvement of next-generation high-efficiency solid-state lighting and high-power electronics. Here, we report InGaN/GaN LEDs with ultralow TD density and improved efficiency on a sapphire substrate, on which a near strain-free GaN compliant buffer layer was grown by remote plasma atomic layer deposition. This "compliant" buffer layer is capable of relaxing strain due to the absorption of misfit dislocations in a region within ~10 nm from the interface, leading to a high-quality overlying GaN epilayer with an unusual TD density as low as 2.2 × 10(5) cm(-2). In addition, this GaN compliant buffer layer exhibits excellent uniformity up to a 6" wafer, revealing a promising means to realize large-area GaN hetero-epitaxy for efficient LEDs and high-power transistors.

  1. Roadmap on semiconductor-cell biointerfaces

    Science.gov (United States)

    Tian, Bozhi; Xu, Shuai; Rogers, John A.; Cestellos-Blanco, Stefano; Yang, Peidong; Carvalho-de-Souza, João L.; Bezanilla, Francisco; Liu, Jia; Bao, Zhenan; Hjort, Martin; Cao, Yuhong; Melosh, Nicholas; Lanzani, Guglielmo; Benfenati, Fabio; Galli, Giulia; Gygi, Francois; Kautz, Rylan; Gorodetsky, Alon A.; Kim, Samuel S.; Lu, Timothy K.; Anikeeva, Polina; Cifra, Michal; Krivosudský, Ondrej; Havelka, Daniel; Jiang, Yuanwen

    2018-05-01

    This roadmap outlines the role semiconductor-based materials play in understanding the complex biophysical dynamics at multiple length scales, as well as the design and implementation of next-generation electronic, optoelectronic, and mechanical devices for biointerfaces. The roadmap emphasizes the advantages of semiconductor building blocks in interfacing, monitoring, and manipulating the activity of biological components, and discusses the possibility of using active semiconductor-cell interfaces for discovering new signaling processes in the biological world.

  2. Heteroepitaxial Growth of Germanium-on-Silicon Using Ultrahigh-Vacuum Chemical Vapor Deposition with RF Plasma Enhancement

    Science.gov (United States)

    Alharthi, Bader; Grant, Joshua M.; Dou, Wei; Grant, Perry C.; Mosleh, Aboozar; Du, Wei; Mortazavi, Mansour; Li, Baohua; Naseem, Hameed; Yu, Shui-Qing

    2018-05-01

    Germanium (Ge) films have been grown on silicon (Si) substrate by ultrahigh-vacuum chemical vapor deposition with plasma enhancement (PE). Argon plasma was generated using high-power radiofrequency (50 W) to assist in germane decomposition at low temperature. The growth temperature was varied in the low range of 250°C to 450°C to make this growth process compatible with complementary metal-oxide-semiconductor technology. The material and optical properties of the grown Ge films were investigated. The material quality was determined by Raman and x-ray diffraction techniques, revealing growth of crystalline films in the temperature range of 350°C to 450°C. Photoluminescence spectra revealed improved optical quality at growth temperatures of 400°C and 450°C. Furthermore, material quality study using transmission electron microscopy revealed existence of defects in the Ge layer grown at 400°C. Based on the etch pit density, the average threading dislocation density in the Ge layer obtained at this growth temperature was measured to be 4.5 × 108 cm-2. This result was achieved without any material improvement steps such as use of graded buffer or thermal annealing. Comparison between PE and non-plasma-enhanced growth, in the same machine at otherwise the same growth conditions, indicated increased growth rate and improved material and optical qualities for PE growth.

  3. Scanning electron microscopy of semiconductor materials

    International Nuclear Information System (INIS)

    Bresse, J.F.; Dupuy, M.

    1978-01-01

    The use of scanning electron microscopy in semiconductors opens up a large field of use. The operating modes lending themselves to the study of semiconductors are the induced current, cathodoluminescence and the use of the potential contrast which can also be applied very effectively to the study of the devices (planar in particular). However, a thorough knowledge of the mechanisms of the penetration of electrons, generation and recombination of generated carriers in a semiconductor is necessary in order to attain a better understanding of the operating modes peculiar to semiconductors [fr

  4. Reflection technique for thermal mapping of semiconductors

    Science.gov (United States)

    Walter, Martin J.

    1989-06-20

    Semiconductors may be optically tested for their temperatures by illuminating them with tunable monochromatic electromagnetic radiation and observing the light reflected off of them. A transition point will occur when the wavelength of the light corresponds with the actual band gap energy of the semiconductor. At the transition point, the image of the semiconductor will appreciably darken as the light is transmitted through it, rather than being reflected off of it. The wavelength of the light at the transition point corresponds to the actual band gap energy and the actual temperature of the semiconductor.

  5. 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.

  6. Metallurgy and purification of semiconductor materials

    International Nuclear Information System (INIS)

    Mughal, G.R.; Ali, M.M.; Ali, I.

    1996-01-01

    In this article the metallurgical aspects of semiconductor science and technology have been stressed here rather than of the physical and electronic aspect of the subject. Semiconductor technology has not merely presented the metallurgist with new challenges. The ease with which the semiconductor planes cleave make possible, the preparation and study of virgin surface. Semiconductor materials were being widely employed in the study of sub-boundaries and structures and can largely contribute to the study of certain aspects of nucleation and growth, precipitation phenomena, mechanical behaviour, in metallurgy. (A.B.)

  7. 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...

  8. Semiconductor Lasers Stability, Instability and Chaos

    CERN Document Server

    Ohtsubo, Junji

    2008-01-01

    This monograph describes fascinating recent progress in the field of chaos, stability and instability of semiconductor lasers. Applications and future prospects are discussed in detail. The book emphasizes the various dynamics induced in semiconductor lasers by optical and electronic feedback, optical injection, and injection current modulation. Recent results of both theoretical and experimental investigations are presented. Demonstrating applications of semiconductor laser chaos, control and noise, Semiconductor Lasers describes suppression and chaotic secure communications. For those who are interested in optics but not familiar with nonlinear systems, a brief introduction to chaos analysis is presented.

  9. Method of manufacturing a semiconductor sensor device and semiconductor sensor device

    NARCIS (Netherlands)

    2009-01-01

    The invention relates to a method of manufacturing a semiconductor sensor device (10) for sensing a substance comprising a plurality of mutually parallel mesa-shaped semiconductor regions (1) which are formed on a surface of a semiconductor body (11) and which are connected at a first end to a first

  10. Ultrafast laser-semiconductor interactions

    International Nuclear Information System (INIS)

    Schile, L.A.

    1996-01-01

    Studies of the ultrafast (< 100 fs) interactions of infrared, sub-100 fs laser pulses with IR, photosensitive semiconductor materials InGaAs, InSb, and HgCdTe are reported. Both the carrier dynamics and the associated Terahertz radiation from these materials are discussed. The most recent developments of femtosecond (< 100 fs) Optical Parametric Oscillators (OPO) has extended the wavelength range from the visible to 5.2 μm. The photogenerated semiconductor free carrier dynamics are determined in the 77 to 300 degrees K temperature range using the Transmission Correlation Peak (TCP) method. The electron-phonon scattering times are typically 200 - 600 fs. Depending upon the material composition and substrate on which the IR crystalline materials are deposited, the nonlinear TCP absorption gives recombination rates as fast as 10's of picoseconds. For the HgCdTe, there exists a 400 fs electron-phonon scattering process along with a much longer 3600 fs loss process. Studies of the interactions of these ultrashort laser pulses with semiconductors produce Terahertz (Thz) radiative pulses. With undoped InSb, there is a substantial change in the spectral content of this THz radiation between 80 - 260 degrees K while the spectrum of Te-doped InSb remains nearly unchanged, an effect attributed to its mobility being dominated by impurity scattering. At 80 degrees K, the terahertz radiation from undoped InSb is dependent on wavelength, with both a higher frequency spectrum and much larger amplitudes generated at longer wavelengths. No such effect is observed at 260 degrees K. Finally, new results on the dependence of the emitted THz radiation on the InSb crystal's orientation is presented

  11. Ion implantation in semiconductor bodies

    International Nuclear Information System (INIS)

    Badawi, M.H.

    1984-01-01

    Ions are selectively implanted into layers of a semiconductor substrate of, for example, semi-insulating gallium arsenide via a photoresist implantation mask and a metallic layer of, for example, titanium disposed between the substrate surface and the photoresist mask. After implantation the mask and metallic layer are removed and the substrate heat treated for annealing purposes. The metallic layer acts as a buffer layer and prevents possible contamination of the substrate surface, by photoresist residues, at the annealing stage. Such contamination would adversely affect the electrical properties of the substrate surface, particularly gallium arsenide substrates. (author)

  12. Method of manufacturing semiconductor devices

    International Nuclear Information System (INIS)

    Sun, Y.S.E.

    1980-01-01

    A method of improving the electrical characteristics of semiconductor devices such as SCR's, rectifiers and triacs during their manufacture is described. The system consists of electron irradiation at an energy in excess of 250 KeV and most preferably between 1.5 and 12 MeV, producing an irradiation dose of between 5.10 12 and 5.10 15 electrons per sq. cm., and at a temperature in excess of 100 0 C preferably between 150 and 375 0 C. (U.K.)

  13. Physics with isotopically controlled semiconductors

    International Nuclear Information System (INIS)

    Haller, E.E.

    1994-08-01

    Control of the isotopic composition of semiconductors offers a wide range of new scientific opportunities. In this paper a number of recent results obtained with isotopically pure as well as deliberately mixed diamond and Ge bulk single crystals and Ge isotope superlattices will be reviewed. Isotopic composition affects several properties such as phonon energies, bandstructure and lattice constant in subtle but theoretically well understood ways. Large effects are observed for thermal conductivity, local vibrational modes of impurities and after neutron transmutation doping (NTD). Several experiments which could profit greatly from isotope control are proposed

  14. Theory of semiconductor laser cooling

    Science.gov (United States)

    Rupper, Greg

    Recently laser cooling of semiconductors has received renewed attention, with the hope that a semiconductor cooler might be able to achieve cryogenic temperatures. In order to study semiconductor laser cooling at cryogenic temperatures, it is crucial that the theory include both the effects of excitons and the electron-hole plasma. In this dissertation, I present a theoretical analysis of laser cooling of bulk GaAs based on a microscopic many-particle theory of absorption and luminescence of a partially ionized electron-hole plasma. This theory has been analyzed from a temperature 10K to 500K. It is shown that at high temperatures (above 300K), cooling can be modeled using older models with a few parameter changes. Below 200K, band filling effects dominate over Auger recombination. Below 30K excitonic effects are essential for laser cooling. In all cases, excitonic effects make cooling easier then predicted by a free carrier model. The initial cooling model is based on the assumption of a homogeneous undoped semiconductor. This model has been systematically modified to include effects that are present in real laser cooling experiments. The following modifications have been performed. (1) Propagation and polariton effects have been included. (2) The effect of p-doping has been included. (n-doping can be modeled in a similar fashion.) (3) In experiments, a passivation layer is required to minimize non-radiative recombination. The passivation results in a npn heterostructure. The effect of the npn heterostructure on cooling has been analyzed. (4) The effect of a Gaussian pump beam was analyzed and (5) Some of the parameters in the cooling model have a large uncertainty. The effect of modifying these parameters has been analyzed. Most of the extensions to the original theory have only had a modest effect on the overall results. However we find that the current passivation technique may not be sufficient to allow cooling. The passivation technique currently used appears

  15. Chaotic bursting in semiconductor lasers

    Science.gov (United States)

    Ruschel, Stefan; Yanchuk, Serhiy

    2017-11-01

    We investigate the dynamic mechanisms for low frequency fluctuations in semiconductor lasers subjected to delayed optical feedback, using the Lang-Kobayashi model. This system of delay differential equations displays pronounced envelope dynamics, ranging from erratic, so called low frequency fluctuations to regular pulse packages, if the time scales of fast oscillations and envelope dynamics are well separated. We investigate the parameter regions where low frequency fluctuations occur and compute their Lyapunov spectra. Using the geometric singular perturbation theory, we study this intermittent chaotic behavior and characterize these solutions as bursting slow-fast oscillations.

  16. Processing of insulators and semiconductors

    Science.gov (United States)

    Quick, Nathaniel R.; Joshi, Pooran C.; Duty, Chad Edward; Jellison, Jr., Gerald Earle; Angelini, Joseph Attilio

    2015-06-16

    A method is disclosed for processing an insulator material or a semiconductor material. The method includes pulsing a plasma lamp onto the material to diffuse a doping substance into the material, to activate the doping substance in the material or to metallize a large area region of the material. The method may further include pulsing a laser onto a selected region of the material to diffuse a doping substance into the material, to activate the doping substance in the material or to metallize a selected region of the material.

  17. Bistable amphoteric centers in semiconductors

    International Nuclear Information System (INIS)

    Nikitina, A. G.; Zuev, V. V.

    2008-01-01

    It is shown that, at thermodynamic equilibrium, the release of charge carriers from the localized states of bistable amphoteric centers into quasi-free states depends on the degree of compensation. This brings about different functional dependences of the concentration of free charge carriers on temperature. It is found that, in uncompensated semiconductors, the concentration of free charge carriers follows the same dependence in the case of bistable amphoteric centers and bistable amphoteric U - centers, although the distributions of charge carriers over the charge states and configurations are different for these types of centers. The results can be used for interpreting various experimental data insufficiently explained in the context of the traditional approach

  18. Electron beam writing on semiconductors

    International Nuclear Information System (INIS)

    Bierhenke, H.; Kutzer, E.; Pascher, A.; Plitzner, H.; Rummel, P.; Siemens A.G., Muenchen; Siemens A.G., Muenchen

    1979-08-01

    Reported are the results of the 3 1/2 year research project 'Electron beam Writing on Semiconductors'. Work has been done in the field of direct wafer exposure techniques, and of mask making. Described are resist technology, setting up of a research device, exploration of alignment procedures, manufacturing of devices and their radiation influence. Furthermore, investigations and measurements of an electron beam machine bought for mask making purposes, the development of LSI-circuits with this machine, the software necessary and important developments of digital subsystems are reported. (orig.) [de

  19. 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

  20. Investigations on Substrate Temperature-Induced Growth Modes of Organic Semiconductors at Dielectric/semiconductor Interface and Their Correlation with Threshold Voltage Stability in Organic Field-Effect Transistors.

    Science.gov (United States)

    Padma, Narayanan; Maheshwari, Priya; Bhattacharya, Debarati; Tokas, Raj B; Sen, Shashwati; Honda, Yoshihide; Basu, Saibal; Pujari, Pradeep Kumar; Rao, T V Chandrasekhar

    2016-02-10

    Influence of substrate temperature on growth modes of copper phthalocyanine (CuPc) thin films at the dielectric/semiconductor interface in organic field effect transistors (OFETs) is investigated. Atomic force microscopy (AFM) imaging at the interface reveals a change from 'layer+island' to "island" growth mode with increasing substrate temperatures, further confirmed by probing the buried interfaces using X-ray reflectivity (XRR) and positron annihilation spectroscopic (PAS) techniques. PAS depth profiling provides insight into the details of molecular ordering while positron lifetime measurements reveal the difference in packing modes of CuPc molecules at the interface. XRR measurements show systematic increase in interface width and electron density correlating well with the change from layer + island to coalesced huge 3D islands at higher substrate temperatures. Study demonstrates the usefulness of XRR and PAS techniques to study growth modes at buried interfaces and reveals the influence of growth modes of semiconductor at the interface on hole and electron trap concentrations individually, thereby affecting hysteresis and threshold voltage stability. Minimum hole trapping is correlated to near layer by layer formation close to the interface at 100 °C and maximum to the island formation with large voids between the grains at 225 °C.

  1. Suitability of integrated protection diodes from diverse semiconductor technologies

    NARCIS (Netherlands)

    van Wanum, Maurice; Lebouille, Tom; Visser, Guido; van Vliet, Frank Edward

    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

  2. Semiconductor X-ray detectors

    CERN Document Server

    Lowe, Barrie Glyn

    2014-01-01

    Identifying and measuring the elemental x-rays released when materials are examined with particles (electrons, protons, alpha particles, etc.) or photons (x-rays and gamma rays) is still considered to be the primary analytical technique for routine and non-destructive materials analysis. The Lithium Drifted Silicon (Si(Li)) X-Ray Detector, with its good resolution and peak to background, pioneered this type of analysis on electron microscopes, x-ray fluorescence instruments, and radioactive source- and accelerator-based excitation systems. Although rapid progress in Silicon Drift Detectors (SDDs), Charge Coupled Devices (CCDs), and Compound Semiconductor Detectors, including renewed interest in alternative materials such as CdZnTe and diamond, has made the Si(Li) X-Ray Detector nearly obsolete, the device serves as a useful benchmark and still is used in special instances where its large, sensitive depth is essential. Semiconductor X-Ray Detectors focuses on the history and development of Si(Li) X-Ray Detect...

  3. Semiconductor nanostructures for artificial photosynthesis

    Science.gov (United States)

    Yang, Peidong

    2012-02-01

    Nanowires, with their unique capability to bridge the nanoscopic and macroscopic worlds, have already been demonstrated as important materials for different energy conversion. One emerging and exciting direction is their application for solar to fuel conversion. The generation of fuels by the direct conversion of solar energy in a fully integrated system is an attractive goal, but no such system has been demonstrated that shows the required efficiency, is sufficiently durable, or can be manufactured at reasonable cost. One of the most critical issues in solar water splitting is the development of a suitable photoanode with high efficiency and long-term durability in an aqueous environment. Semiconductor nanowires represent an important class of nanostructure building block for direct solar-to-fuel application because of their high surface area, tunable bandgap and efficient charge transport and collection. Nanowires can be readily designed and synthesized to deterministically incorporate heterojunctions with improved light absorption, charge separation and vectorial transport. Meanwhile, it is also possible to selectively decorate different oxidation or reduction catalysts onto specific segments of the nanowires to mimic the compartmentalized reactions in natural photosynthesis. In this talk, I will highlight several recent examples in this lab using semiconductor nanowires and their heterostructures for the purpose of direct solar water splitting.

  4. Dopants and defects in semiconductors

    CERN Document Server

    McCluskey, Matthew D

    2012-01-01

    "The book goes beyond the usual textbook in that it provides more specific examples of real-world defect physics … The book will be most useful for beginning graduate students in materials science. … an easy reading, broad introductory overview of the field …"-Materials Today, July-August 2012"… well written, with clear, lucid explanations …"-Chemistry World"The scientific development towards the method of controllable doping transformed the erratic and not reproducible family of semiconductor materials into the truly wonderful basis of modern microelectronics. This book tells the remarkable success story and I recommend it!"-Hans J. Queisser, Max-Planck-Institute, Stuttgart, Germany"McCluskey and Haller have written an outstanding modern guide to this field that will be useful to newcomers, and also to active researchers who want to broaden their horizons, as a means to learn the capabilities and limitations of the many techniques that are used in semiconductor-defect science."-Professor Michael J....

  5. The ATLAS semiconductor tracker (SCT)

    International Nuclear Information System (INIS)

    Jackson, J.N.

    2005-01-01

    The ATLAS detector (CERN,LHCC,94-43 (1994)) is designed to study a wide range of physics at the CERN Large Hadron Collider (LHC) at luminosities up to 10 34 cm -2 s -1 with a bunch-crossing rate of 40 MHz. The Semiconductor Tracker (SCT) forms a key component of the Inner Detector (vol. 1, ATLAS TDR 4, CERN,LHCC 97-16 (1997); vol. 2, ATLAS TDR 5, CERN,LHCC 97-17 (1997)) which is situated inside a 2 T solenoid field. The ATLAS Semiconductor Tracker (SCT) utilises 4088 silicon modules with binary readout mounted on carbon fibre composite structures arranged in the forms of barrels in the central region and discs in the forward region. The construction of the SCT is now well advanced. The design of the SCT modules, services and support structures will be briefly outlined. A description of the various stages in the construction process will be presented with examples of the performance achieved and the main difficulties encountered. Finally, the current status of the construction is reviewed

  6. Charge transport in organic semiconductors.

    Science.gov (United States)

    Bässler, Heinz; Köhler, Anna

    2012-01-01

    Modern optoelectronic devices, such as light-emitting diodes, field-effect transistors and organic solar cells require well controlled motion of charges for their efficient operation. The understanding of the processes that determine charge transport is therefore of paramount importance for designing materials with improved structure-property relationships. Before discussing different regimes of charge transport in organic semiconductors, we present a brief introduction into the conceptual framework in which we interpret the relevant photophysical processes. That is, we compare a molecular picture of electronic excitations against the Su-Schrieffer-Heeger semiconductor band model. After a brief description of experimental techniques needed to measure charge mobilities, we then elaborate on the parameters controlling charge transport in technologically relevant materials. Thus, we consider the influences of electronic coupling between molecular units, disorder, polaronic effects and space charge. A particular focus is given to the recent progress made in understanding charge transport on short time scales and short length scales. The mechanism for charge injection is briefly addressed towards the end of this chapter.

  7. Modeling of semiconductor nanostructures and semiconductor-electrolyte interfaces

    International Nuclear Information System (INIS)

    Birner, Stefan

    2011-01-01

    The main objective of Part I is to give an overview of some of the methods that have been implemented into the nextnano 3 software. Examples are discussed that give insight into doping, strain and mobility. Applications of the single-band Schroedinger equation include three-dimensional superlattices, and a qubit that is manipulated by a magnetic field. Results of the multi-band k.p method are presented for HgTe-CdTe and InAs-GaSb superlattices, and for a SiGe-Si quantum cascade structure. Particular focus is put on a detailed description of the contact block reduction (CBR) method that has been developed within our research group. By means of this approach, quantum transport in the ballistic limit in one, two and three dimensions can be calculated. I provide a very detailed description of the algorithm and present several well documented examples that highlight the key points of this method. Calculating quantum transport in three dimensions is a very challenging task where computationally efficient algorithms - apart from the CBR method - are not available yet. Part II describes the methods that I have implemented into the nextnano 3 software for calculating systems that consist of a combination of semiconductor materials and liquids. These biosensors have a solid-electrolyte interface, and the charges in the solid and in the electrolyte are coupled to each other through the Poisson-Boltzmann equation. I apply this model to a silicon based protein sensor, where I solve the Schroedinger equation together with the Poisson-Boltzmann equation self-consistently, and compare theoretical results with experiment. Furthermore, I have developed a novel approach to model the charge density profiles at semiconductor-electrolyte interfaces that allows us to distinguish hydrophobic and hydrophilic interfaces. Our approach extends previous work where ion specific potentials of mean force describe the distribution of ion species at the interface. I apply this new model to recently

  8. Modeling of semiconductor nanostructures and semiconductor-electrolyte interfaces

    Energy Technology Data Exchange (ETDEWEB)

    Birner, Stefan

    2011-11-15

    The main objective of Part I is to give an overview of some of the methods that have been implemented into the nextnano{sup 3} software. Examples are discussed that give insight into doping, strain and mobility. Applications of the single-band Schroedinger equation include three-dimensional superlattices, and a qubit that is manipulated by a magnetic field. Results of the multi-band k.p method are presented for HgTe-CdTe and InAs-GaSb superlattices, and for a SiGe-Si quantum cascade structure. Particular focus is put on a detailed description of the contact block reduction (CBR) method that has been developed within our research group. By means of this approach, quantum transport in the ballistic limit in one, two and three dimensions can be calculated. I provide a very detailed description of the algorithm and present several well documented examples that highlight the key points of this method. Calculating quantum transport in three dimensions is a very challenging task where computationally efficient algorithms - apart from the CBR method - are not available yet. Part II describes the methods that I have implemented into the nextnano{sup 3} software for calculating systems that consist of a combination of semiconductor materials and liquids. These biosensors have a solid-electrolyte interface, and the charges in the solid and in the electrolyte are coupled to each other through the Poisson-Boltzmann equation. I apply this model to a silicon based protein sensor, where I solve the Schroedinger equation together with the Poisson-Boltzmann equation self-consistently, and compare theoretical results with experiment. Furthermore, I have developed a novel approach to model the charge density profiles at semiconductor-electrolyte interfaces that allows us to distinguish hydrophobic and hydrophilic interfaces. Our approach extends previous work where ion specific potentials of mean force describe the distribution of ion species at the interface. I apply this new model

  9. Novel room temperature ferromagnetic semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    Gupta, Amita [KTH Royal Inst. of Technology, Stockholm (Sweden)

    2004-06-01

    Today's information world, bits of data are processed by semiconductor chips, and stored in the magnetic disk drives. But tomorrow's information technology may see magnetism (spin) and semiconductivity (charge) combined in one 'spintronic' device that exploits both charge and 'spin' to carry data (the best of two worlds). Spintronic devices such as spin valve transistors, spin light emitting diodes, non-volatile memory, logic devices, optical isolators and ultra-fast optical switches are some of the areas of interest for introducing the ferromagnetic properties at room temperature in a semiconductor to make it multifunctional. The potential advantages of such spintronic devices will be higher speed, greater efficiency, and better stability at a reduced power consumption. This Thesis contains two main topics: In-depth understanding of magnetism in Mn doped ZnO, and our search and identification of at least six new above room temperature ferromagnetic semiconductors. Both complex doped ZnO based new materials, as well as a number of nonoxides like phosphides, and sulfides suitably doped with Mn or Cu are shown to give rise to ferromagnetism above room temperature. Some of the highlights of this work are discovery of room temperature ferromagnetism in: (1) ZnO:Mn (paper in Nature Materials, Oct issue, 2003); (2) ZnO doped with Cu (containing no magnetic elements in it); (3) GaP doped with Cu (again containing no magnetic elements in it); (4) Enhancement of Magnetization by Cu co-doping in ZnO:Mn; (5) CdS doped with Mn, and a few others not reported in this thesis. We discuss in detail the first observation of ferromagnetism above room temperature in the form of powder, bulk pellets, in 2-3 mu-m thick transparent pulsed laser deposited films of the Mn (<4 at. percent) doped ZnO. High-resolution transmission electron microscopy (HRTEM) and electron energy loss spectroscopy (EELS) spectra recorded from 2 to 200nm areas showed homogeneous

  10. Vancouver Island gas supply

    International Nuclear Information System (INIS)

    Des Brisay, C.

    2005-01-01

    Terasen Gas is pursuing alternatives for the supply of additional natural gas capacity to Vancouver Island. Its subsidiary, Terasen Gas (Vancouver Island) Inc. (TGVI), is responding to the need for delivery of increased gas supply and, is supporting plans for new gas-fired power generation on Vancouver Island. TGVI's proposal for new natural gas capacity involves a combination of compression and pipeline loops as well as the addition of a storage facility for liquefied natural gas (LNG) at Mt. Hayes to help manage price volatility. This presentation outlined the objectives and components of the resource planning process, including demand forecast scenarios and the preferred infrastructure options. tabs., figs

  11. Hybrid anode for semiconductor radiation detectors

    Science.gov (United States)

    Yang, Ge; Bolotnikov, Aleksey E; Camarda, Guiseppe; Cui, Yonggang; Hossain, Anwar; Kim, Ki Hyun; James, Ralph B

    2013-11-19

    The present invention relates to a novel hybrid anode configuration for a radiation detector that effectively reduces the edge effect of surface defects on the internal electric field in compound semiconductor detectors by focusing the internal electric field of the detector and redirecting drifting carriers away from the side surfaces of the semiconductor toward the collection electrode(s).

  12. Terahertz plasmonics with semiconductor surfaces and antennas

    NARCIS (Netherlands)

    Gómez Rivas, J.; Berrier, A.

    2009-01-01

    Semiconductors have a Drude-like behavior at terahertz (THz) frequencies similar to metals at optical frequencies. Narrow band gap semiconductors have a dielectric constant with a negative real component and a relatively small imaginary component. This permittivity is characteristic of noble metals

  13. Redox properties of small semiconductor particles

    International Nuclear Information System (INIS)

    Liver, N.; Nitzan, A.

    1992-01-01

    The size dependence of electrical and thermodynamic quantities of intermediate-sized semiconductor particles in an electrolyte solution with a given redox pair are studied. The equilibrium constant for this system is then derived based on the relationship of the electrolytic redox components to the size, charges, and concentration of the semiconductor particles. 25 refs., 9 figs., 1 tab

  14. neutron-Induced Failures in semiconductor Devices

    Energy Technology Data Exchange (ETDEWEB)

    Wender, Stephen Arthur [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-03-13

    Single Event Effects are a very significant failure mode in modern semiconductor devices that may limit their reliability. Accelerated testing is important for semiconductor industry. Considerable more work is needed in this field to mitigate the problem. Mitigation of this problem will probably come from Physicists and Electrical Engineers working together

  15. Semiconductor composition containing iron, dysprosium, and terbium

    Science.gov (United States)

    Pooser, Raphael C.; Lawrie, Benjamin J.; Baddorf, Arthur P.; Malasi, Abhinav; Taz, Humaira; Farah, Annettee E.; Kalyanaraman, Ramakrishnan; Duscher, Gerd Josef Mansfred; Patel, Maulik K.

    2017-09-26

    An amorphous semiconductor composition includes 1 to 70 atomic percent iron, 15 to 65 atomic percent dysprosium, 15 to 35 atomic percent terbium, balance X, wherein X is at least one of an oxidizing element and a reducing element. The composition has an essentially amorphous microstructure, an optical transmittance of at least 50% in at least the visible spectrum and semiconductor electrical properties.

  16. Epitaxy of semiconductor-superconductor nanowires

    DEFF Research Database (Denmark)

    Krogstrup, P.; Ziino, N.L.B.; Chang, W.

    2015-01-01

    Controlling the properties of semiconductor/metal interfaces is a powerful method for designing functionality and improving the performance of electrical devices. Recently semiconductor/superconductor hybrids have appeared as an important example where the atomic scale uniformity of the interface...

  17. Power semiconductor device adaptive cooling assembly

    NARCIS (Netherlands)

    2011-01-01

    The invention relates to a power semiconductor device (100) cooling assembly for cooling a power semiconductor device (100), wherein the assembly comprises an actively cooled heat sink (102) and a controller (208; 300), wherein the controller (208; 300) is adapted for adjusting the cooling

  18. Two-fluid hydrodynamic model for semiconductors

    DEFF Research Database (Denmark)

    Maack, Johan Rosenkrantz; Mortensen, N. Asger; Wubs, Martijn

    2018-01-01

    The hydrodynamic Drude model (HDM) has been successful in describing the optical properties of metallic nanostructures, but for semiconductors where several different kinds of charge carriers are present an extended theory is required. We present a two-fluid hydrodynamic model for semiconductors...

  19. Miniature semiconductor detectors for in vivo dosimetry

    International Nuclear Information System (INIS)

    Rosenfeld, A. B.; Cutajar, D.; Lerch, M. L. F.; Takacs, G.; Cornelius, I. M.; Yudelev, M.; Zaider, M.

    2006-01-01

    Silicon mini-semiconductor detectors are found in wide applications for in vivo personal dosimetry and dosimetry and Micro-dosimetry of different radiation oncology modalities. These applications are based on integral and spectroscopy modes of metal oxide semiconductor field effect transistor and silicon p-n junction detectors. The advantages and limitations of each are discussed. (authors)

  20. Dispersion-induced nonlinearities in semiconductors

    DEFF Research Database (Denmark)

    Mørk, Jesper; Mecozzi, A.

    2002-01-01

    A dispersive and saturable medium is shown, under very general conditions, to possess ultrafast dynamic behaviour due to non-adiabatic polarisation dynamics. Simple analytical expressions relating the effect to the refractive index dispersion of a semiconductor ire derived and the magnitude...... of the equivalent Kerr coefficient is shown to be in qualitative agreement with measurements on active semiconductor waveguides....

  1. Electronic structure of filled tetrahedral semiconductors

    NARCIS (Netherlands)

    Wood, D.M.; Zunger, Alex; Groot, R. de

    1985-01-01

    We discuss the susceptibility of zinc-blende semiconductors to band-structure modification by insertion of small atoms at their tetrahedral interstitial states. GaP is found to become a direct-gap semiconductor with two He atoms present at its interstitial sites; Si does not. Analysis of the factors

  2. Apparatus for testing semiconductor devices and capacitors

    International Nuclear Information System (INIS)

    York, R.A.

    1984-01-01

    An apparatus is provided for testing semiconductor devices. The apparatus tests the impedance of the semiconductor devices in both conducting and non-conducting states to detect semiconductors whose impedance in the conducting state is too high or whose impedance in the non-conducting state is too low. The apparatus uses a battery source for low voltage d.c. The circuitry for detecting when the impedance is too high in the conducting state includes a lamp in series with the battery source and the semiconductor device, whereby the impedance of the semiconductor device determines whether sufficient current will flow through the lamp to cause the lamp to illuminate. A d.c. to d.c. converter is provided to boost the voltage from the battery source to a relatively high voltage d.c. The relatively high voltage d.c. can be connected by a switch to circuitry for detecting when the impedance of the semiconductor device in the non-conducting state is too low. The circuitry for detecting when the impedance of the semiconductor device is too low includes a resistor which senses the current flowing in the device and converts the current into a voltage proportional to the leakage current. This voltage is then compared against a fixed reference. Further circuitry is provided for providing a visual indication when the voltage representative of leakage in relation to the reference signal indicates that there is excessive current flow through the semiconductor device

  3. Island formation without attractive interaction

    NARCIS (Netherlands)

    Jansen, A.P.J.

    2008-01-01

    We show that adsorbates on surfaces can form islands even if there are no attractive interactions. Instead, strong repulsion between adsorbates at short distances can lead to islands, because such islands increase the entropy of the adsorbates that are not part of the islands. We suggest that this

  4. 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.

  5. 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...

  6. Semiconductor Lasers Stability, Instability and Chaos

    CERN Document Server

    Ohtsubo, Junji

    2013-01-01

    This third edition of “Semiconductor Lasers, Stability, Instability and Chaos” was significantly extended.  In the previous edition, the dynamics and characteristics of chaos in semiconductor lasers after the introduction of the fundamental theory of laser chaos and chaotic dynamics induced by self-optical feedback and optical injection was discussed. Semiconductor lasers with new device structures, such as vertical-cavity surface-emitting lasers and broad-area semiconductor lasers, are interesting devices from the viewpoint of chaotic dynamics since they essentially involve chaotic dynamics even in their free-running oscillations. These topics are also treated with respect to the new developments in the current edition. Also the control of such instabilities and chaos control are critical issues for applications. Another interesting and important issue of semiconductor laser chaos in this third edition is chaos synchronization between two lasers and the application to optical secure communication. One o...

  7. 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,...

  8. Two dimensional numerical simulations of carrier dynamics during time-resolved photoluminescence decays in two-photon microscopy measurements in semiconductors

    International Nuclear Information System (INIS)

    Kanevce, Ana; Kuciauskas, Darius; Levi, Dean H.; Johnston, Steven W.; Allende Motz, Alyssa M.

    2015-01-01

    We use two-dimensional numerical simulations to analyze high spatial resolution time-resolved spectroscopy data. This analysis is applied to two-photon excitation time-resolved photoluminescence (2PE-TRPL) but is broadly applicable to all microscopic time-resolved techniques. By solving time-dependent drift-diffusion equations, we gain insight into carrier dynamics and transport characteristics. Accurate understanding of measurement results establishes the limits and potential of the measurement and enhances its value as a characterization method. Diffusion of carriers outside of the collection volume can have a significant impact on the measured decay but can also provide an estimate of carrier mobility as well as lifetime. In addition to material parameters, the experimental conditions, such as spot size and injection level, can impact the measurement results. Although small spot size provides better resolution, it also increases the impact of diffusion on the decay; if the spot size is much smaller than the diffusion length, it impacts the entire decay. By reproducing experimental 2PE-TRPL decays, the simulations determine the bulk carrier lifetime from the data. The analysis is applied to single-crystal and heteroepitaxial CdTe, material important for solar cells, but it is also applicable to other semiconductors where carrier diffusion from the excitation volume could affect experimental measurements

  9. Coalescence of magnetic islands

    International Nuclear Information System (INIS)

    Pellat, R.

    1982-01-01

    The paper gives the analytical theory of the coalescence instability and of a new, one island, instability. These instabilities are expected to be relevant for the disruptions observed in Tokamak experiments and astrophysical plasmas

  10. Heat Island Compendium

    Science.gov (United States)

    Heat islands can be mitigated through measures like planting trees and vegetation, installing green roofs and cool roofs, and using cool pavements. The compendium describes all of these strategies and shows how communities around the country are being used

  11. Three Mile Island revisited

    International Nuclear Information System (INIS)

    MacLeod, G.K.

    1986-01-01

    The accident at Three Mile Island proved that the Pennsylvania Department of Health lacked the tools to deal with the serious health consequences that occurred during and after this emergency. Despite the relative safety of nuclear power generation, we must be better prepared for the health and medical consequences of serous radiation emergencies. The author reviews the Three Mile Island accident through the eyes of newspaper reporters

  12. Self-assembly of tin wires via phase transformation of heteroepitaxial germanium-tin on germanium substrate

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Wei; Li, Lingzi; Yeo, Yee-Chia, E-mail: yeo@ieee.org [Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117576 (Singapore); Tok, Eng Soon [Department of Physics, National University of Singapore, Singapore 117551 (Singapore)

    2015-06-14

    This work demonstrates and describes for the first time an unusual strain-relaxation mechanism by the formation and self-assembly of well-ordered tin wires during the thermal annealing of epitaxial Ge{sub 0.83}Sn{sub 0.17}-on-Ge(001) substrate. Fully strained germanium-tin alloys (Ge{sub 0.83}Sn{sub 0.17}) were epitaxially grown on Ge(001) substrate by molecular beam epitaxy. The morphological and compositional evolution of Ge{sub 0.83}Sn{sub 0.17} during thermal annealing is studied by atomic force microscopy, X-ray diffraction, transmission electron microscopy. Under certain annealing conditions, the Ge{sub 0.83}Sn{sub 0.17} layer decomposes into two stable phases, and well-defined Sn wires that are preferentially oriented along two orthogonal 〈100〉 azimuths are formed. The formation of the Sn wires is related to the annealing temperature and the Ge{sub 0.83}Sn{sub 0.17} thickness, and can be explained by the nucleation of a grain with Sn islands on the outer front, followed by grain boundary migration. The Sn wire formation process is found to be thermally activated, and an activation enthalpy (E{sub c}) of 0.41 eV is extracted. This thermally activated phase transformation, i.e., 2D epitaxial layer to 3D wires, occurs via a mechanism akin to “cellular precipitation.” This synthesis route of Sn wires opens new possibilities for creation of nanoscale patterns at high-throughput without the need for lithography.

  13. Optical characterization of free electron concentration in heteroepitaxial InN layers using Fourier transform infrared spectroscopy and a 2 × 2 transfer-matrix algebra

    International Nuclear Information System (INIS)

    Katsidis, C. C.; Ajagunna, A. O.; Georgakilas, A.

    2013-01-01

    Fourier Transform Infrared (FTIR) reflectance spectroscopy has been implemented as a non-destructive, non-invasive, tool for the optical characterization of a set of c-plane InN single heteroepitaxial layers spanning a wide range of thicknesses (30–2000 nm). The c-plane (0001) InN epilayers were grown by plasma-assisted molecular beam epitaxy (PAMBE) on GaN(0001) buffer layers which had been grown on Al 2 O 3 (0001) substrates. It is shown that for arbitrary multilayers with homogeneous anisotropic layers having their principal axes coincident with the laboratory coordinates, a 2 × 2 matrix algebra based on a general transfer-matrix method (GTMM) is adequate to interpret their optical response. Analysis of optical reflectance in the far and mid infrared spectral range has been found capable to discriminate between the bulk, the surface and interface contributions of free carriers in the InN epilayers revealing the existence of electron accumulation layers with carrier concentrations in mid 10 19 cm −3 at both the InN surface and the InN/GaN interface. The spectra could be fitted with a three-layer model, determining the different electron concentration and mobility values of the bulk and of the surface and the interface electron accumulation layers in the InN films. The variation of these values with increasing InN thickness could be also sensitively detected by the optical measurements. The comparison between the optically determined drift mobility and the Hall mobility of the thickest sample reveals a value of r H = 1.49 for the Hall factor of InN at a carrier concentration of 1.11 × 10 19 cm −3 at 300°Κ.

  14. Islands and Islandness in Rock Music Lyrics

    Directory of Open Access Journals (Sweden)

    Daniele Mezzana

    2012-05-01

    Full Text Available This paper presents a first exploration, qualitative in character, based on a review of 412 songs produced in the period 1960-2009, about islands in rock music as both social products and social tools potentially contributing to shaping ideas, emotions, will, and desires. An initial taxonomy of 24 themes clustered under five meta-themes of space, lifestyle, emotions, symbolism, and social-political relations is provided, together with some proposals for further research.

  15. TSOM method for semiconductor metrology

    Science.gov (United States)

    Attota, Ravikiran; Dixson, Ronald G.; Kramar, John A.; Potzick, James E.; Vladár, András E.; Bunday, Benjamin; Novak, Erik; Rudack, Andrew

    2011-03-01

    Through-focus scanning optical microscopy (TSOM) is a new metrology method that achieves 3D nanoscale measurement sensitivity using conventional optical microscopes; measurement sensitivities are comparable to what is typical when using scatterometry, scanning electron microscopy (SEM), and atomic force microscopy (AFM). TSOM can be used in both reflection and transmission modes and is applicable to a variety of target materials and shapes. Nanometrology applications that have been demonstrated by experiments or simulations include defect analysis, inspection and process control; critical dimension, photomask, overlay, nanoparticle, thin film, and 3D interconnect metrologies; line-edge roughness measurements; and nanoscale movements of parts in MEMS/NEMS. Industries that could benefit include semiconductor, data storage, photonics, biotechnology, and nanomanufacturing. TSOM is relatively simple and inexpensive, has a high throughput, and provides nanoscale sensitivity for 3D measurements with potentially significant savings and yield improvements in manufacturing.

  16. Semirelativity in semiconductors: a review.

    Science.gov (United States)

    Zawadzki, Wlodek

    2017-09-20

    An analogy between behavior of electrons in narrow-gap semiconductors (NGS) and relativistic electrons in vacuum is reviewed. Energy band structures [Formula: see text] are considered for various NGS materials and their correspondence to the energy-momentum relation in special relativity is emphasized. It is indicated that special relativity for vacuum is analogous to a two-band [Formula: see text] description for NGS. The maximum electron velocity in NGS is [Formula: see text], which corresponds to the light velocity in vacuum. An effective mass of charge carriers in semiconductors is introduced, relating their velocity to quasimomentum and it is shown that this mass depends on electron energy (or velocity) in a way similar to the mass of free relativistic electrons. In [Formula: see text] alloys one can reach vanishing energy gap at which electrons and light holes become three-dimensional massless Dirac fermions. A wavelength [Formula: see text] is defined for NGS, in analogy to the Compton wavelength in relativistic quantum mechanics. It is estimated that [Formula: see text] is on the order of tens of Angstroms in typical semiconducting materials which is experimentally confirmed in tunneling experiments on energy dispersion in the forbidden gap. Statistical properties of the electron gas in NGS are calculated and their similarity is demonstrated to those of the Juttner gas of relativistic particles. Interband electron tunneling in NGS is described and shown to be in close analogy to the predicted but unobserved tunneling between negative and positive energies resulting from the Dirac equation for free electrons. It is demonstrated that the relativistic analogy holds for orbital and spin properties of electrons in the presence of an external magnetic field. In particular, it is shown that the spin magnetic moment of both NGS electrons and relativistic electrons approaches zero with increasing energy. This conclusion is confirmed experimentally for NGS. Electrons

  17. Reconfigurable engineered motile semiconductor microparticles.

    Science.gov (United States)

    Ohiri, Ugonna; Shields, C Wyatt; Han, Koohee; Tyler, Talmage; Velev, Orlin D; Jokerst, Nan

    2018-05-03

    Locally energized particles form the basis for emerging classes of active matter. The design of active particles has led to their controlled locomotion and assembly. The next generation of particles should demonstrate robust control over their active assembly, disassembly, and reconfiguration. Here we introduce a class of semiconductor microparticles that can be comprehensively designed (in size, shape, electric polarizability, and patterned coatings) using standard microfabrication tools. These custom silicon particles draw energy from external electric fields to actively propel, while interacting hydrodynamically, and sequentially assemble and disassemble on demand. We show that a number of electrokinetic effects, such as dielectrophoresis, induced charge electrophoresis, and diode propulsion, can selectively power the microparticle motions and interactions. The ability to achieve on-demand locomotion, tractable fluid flows, synchronized motility, and reversible assembly using engineered silicon microparticles may enable advanced applications that include remotely powered microsensors, artificial muscles, reconfigurable neural networks and computational systems.

  18. High throughput semiconductor deposition system

    Science.gov (United States)

    Young, David L.; Ptak, Aaron Joseph; Kuech, Thomas F.; Schulte, Kevin; Simon, John D.

    2017-11-21

    A reactor for growing or depositing semiconductor films or devices. The reactor may be designed for inline production of III-V materials grown by hydride vapor phase epitaxy (HVPE). The operating principles of the HVPE reactor can be used to provide a completely or partially inline reactor for many different materials. An exemplary design of the reactor is shown in the attached drawings. In some instances, all or many of the pieces of the reactor formed of quartz, such as welded quartz tubing, while other reactors are made from metal with appropriate corrosion resistant coatings such as quartz or other materials, e.g., corrosion resistant material, or stainless steel tubing or pipes may be used with a corrosion resistant material useful with HVPE-type reactants and gases. Using HVPE in the reactor allows use of lower-cost precursors at higher deposition rates such as in the range of 1 to 5 .mu.m/minute.

  19. Magnetic susceptibility of semiconductor melts

    International Nuclear Information System (INIS)

    Kutvitskij, V.A.; Shurygin, P.M.

    1975-01-01

    The temperature dependences chi of various alloys confirm the existence of cluster formations in molten semiconductors, the stability of these formations in melts being considerably affected by the anion nature. The concentrational dependences of the magnetic susceptibility for all the investigated systems exhibit the diamagnetism maxima corresponding to the compound compositions. Heating the melt causes ''smearing'' the maxima, which is related with the cluster structure dissociation. The existence of the maxima concentrational dependence chi corresponding to BiTe and BiSe is found in the isotherms. The non-linear dependence of chi on the composition shows the absence of a single-valued relation between the phase diagram and the chi-diagram for melts

  20. Volatile organometallic and semiconductor materials

    International Nuclear Information System (INIS)

    Dickson, R.S.

    1991-01-01

    This article reports on a project concerned with the metal organic chemical vapour deposition (MOCVD) of mercury-cadmium telluride (MCT) undertaken by a research consortium based in the Clayton area involving Monash University Chemistry Department, Telecom Research Laboratories, and CSIRO Division of Material Sciences and Technology. An M.R. Semicon 226 MOCVD reactor, operating near atmospheric presure with hydrogen carrier gas has been used. Most applications of MCT are direct consequence of its responsiveness to radiation in infrared region spectrum. The main aims of the project were to prepare and assess a range of volatile organometallics that might find use as a dopant sources for MCT, to prepare and study the properties of a range of different lanthanide complexes for MOCVD applications and to fully characterize the semiconductor wafers after growth. 19 refs., 3 figs

  1. Theory of Defects in Semiconductors

    CERN Document Server

    Drabold, David A

    2007-01-01

    Semiconductor science and technology is the art of defect engineering. The theoretical modeling of defects has improved dramatically over the past decade. These tools are now applied to a wide range of materials issues: quantum dots, buckyballs, spintronics, interfaces, amorphous systems, and many others. This volume presents a coherent and detailed description of the field, and brings together leaders in theoretical research. Today's state-of-the-art, as well as tomorrow’s tools, are discussed: the supercell-pseudopotential method, the GW formalism,Quantum Monte Carlo, learn-on-the-fly molecular dynamics, finite-temperature treatments, etc. A wealth of applications are included, from point defects to wafer bonding or the propagation of dislocation.

  2. Semirelativity in semiconductors: a review

    Science.gov (United States)

    Zawadzki, Wlodek

    2017-09-01

    An analogy between behavior of electrons in narrow-gap semiconductors (NGS) and relativistic electrons in vacuum is reviewed. Energy band structures \\varepsilon ≤ft(\\mathbf{k}\\right) are considered for various NGS materials and their correspondence to the energy-momentum relation in special relativity is emphasized. It is indicated that special relativity for vacuum is analogous to a two-band \\mathbf{k}\\centerdot \\mathbf{p} description for NGS. The maximum electron velocity in NGS is u≃ 1× {{10}8}~\\text{cm}~{{\\text{s}}-1} , which corresponds to the light velocity in vacuum. An effective mass of charge carriers in semiconductors is introduced, relating their velocity to quasimomentum and it is shown that this mass depends on electron energy (or velocity) in a way similar to the mass of free relativistic electrons. In \\text{H}{{\\text{g}}1-x}\\text{C}{{\\text{d}}x}\\text{Te} alloys one can reach vanishing energy gap at which electrons and light holes become three-dimensional massless Dirac fermions. A wavelength {λz} is defined for NGS, in analogy to the Compton wavelength in relativistic quantum mechanics. It is estimated that {λz} is on the order of tens of Angstroms in typical semiconducting materials which is experimentally confirmed in tunneling experiments on energy dispersion in the forbidden gap. Statistical properties of the electron gas in NGS are calculated and their similarity is demonstrated to those of the Juttner gas of relativistic particles. Interband electron tunneling in NGS is described and shown to be in close analogy to the predicted but unobserved tunneling between negative and positive energies resulting from the Dirac equation for free electrons. It is demonstrated that the relativistic analogy holds for orbital and spin properties of electrons in the presence of an external magnetic field. In particular, it is shown that the spin magnetic moment of both NGS electrons and relativistic electrons approaches zero with increasing

  3. Semiconductor processing with excimer lasers

    International Nuclear Information System (INIS)

    Young, R.T.; Narayan, J.; Christie, W.H.; van der Leeden, G.A.; Rothe, D.E.; Cheng, L.J.

    1983-01-01

    The advantages of pulsed excimer lasers for semiconductor processing are reviewed. Extensive comparisons of the quality of annealing of ion-implanted Si obtained with XeCl and ruby lasers have been made. The results indicate that irrespective of the large differences in the optical properties of Si at uv and visible wavelengths, the efficiency of usage of the incident energy for annealing is comparable for the two lasers. However, because of the excellent optical beam quality, the XeCl laser can provide superior control of the surface melting and the resulting junction depth. Furthermore, the concentrations of electrically active point defects in the XeCl laser annealed region are 2 to 3 orders of magnitude lower than that obtained from ruby or Nd:YAG lasers. All these results seem to suggest that XeCl lasers should be suitable for fabricating not only solar cells but also the more advanced device structures required for VLSI or VHSIC applications

  4. Photodiodes based on fullerene semiconductor

    International Nuclear Information System (INIS)

    Voz, C.; Puigdollers, J.; Cheylan, S.; Fonrodona, M.; Stella, M.; Andreu, J.; Alcubilla, R.

    2007-01-01

    Fullerene thin films have been deposited by thermal evaporation on glass substrates at room temperature. A comprehensive optical characterization was performed, including low-level optical absorption measured by photothermal deflection spectroscopy. The optical absorption spectrum reveals a direct bandgap of 2.3 eV and absorption bands at 2.8 and 3.6 eV, which are related to the creation of charge-transfer excitons. Various photodiodes on indium-tin-oxide coated glass substrates were also fabricated, using different metallic contacts in order to compare their respective electrical characteristics. The influence of a poly(3,4-ethylenedioxythiophene) poly(styrenesulfonate) buffer layer between the indium-tin-oxide electrode and the fullerene semiconductor is also demonstrated. These results are discussed in terms of the workfunction for each electrode. Finally, the behaviour of the external quantum efficiency is analyzed for the whole wavelength spectrum

  5. Fundamentals of semiconductor processing technology

    CERN Document Server

    El-Kareh, Badih

    1995-01-01

    The drive toward new semiconductor technologies is intricately related to market demands for cheaper, smaller, faster, and more reliable circuits with lower power consumption. The development of new processing tools and technologies is aimed at optimizing one or more of these requirements. This goal can, however, only be achieved by a concerted effort between scientists, engineers, technicians, and operators in research, development, and manufac­ turing. It is therefore important that experts in specific disciplines, such as device and circuit design, understand the principle, capabil­ ities, and limitations of tools and processing technologies. It is also important that those working on specific unit processes, such as lithography or hot processes, be familiar with other unit processes used to manufacture the product. Several excellent books have been published on the subject of process technologies. These texts, however, cover subjects in too much detail, or do not cover topics important to modem tech­ n...

  6. Solid-state NMR of inorganic semiconductors.

    Science.gov (United States)

    Yesinowski, James P

    2012-01-01

    Studies of inorganic semiconductors by solid-state NMR vary widely in terms of the nature of the samples investigated, the techniques employed to observe the NMR signal, and the types of information obtained. Compared with the NMR of diamagnetic non-semiconducting substances, important differences often result from the presence of electron or hole carriers that are the hallmark of semiconductors, and whose theoretical interpretation can be involved. This review aims to provide a broad perspective on the topic for the non-expert by providing: (1) a basic introduction to semiconductor physical concepts relevant to NMR, including common crystal structures and the various methods of making samples; (2) discussions of the NMR spin Hamiltonian, details of some of the NMR techniques and strategies used to make measurements and theoretically predict NMR parameters, and examples of how each of the terms in the Hamiltonian has provided useful information in bulk semiconductors; (3) a discussion of the additional considerations needed to interpret the NMR of nanoscale semiconductors, with selected examples. The area of semiconductor NMR is being revitalized by this interest in nanoscale semiconductors, the great improvements in NMR detection sensitivity and resolution that have occurred, and the current interest in optical pumping and spintronics-related studies. Promising directions for future research will be noted throughout.

  7. The Role of Ge Wetting Layer and Ge Islands in Si MSM Photodetectors

    International Nuclear Information System (INIS)

    Mahmodi, H.; Hashim, M. R.

    2010-01-01

    In this work, Ge thin films were deposited on silicon substrates by radio frequency magnetron sputtering to form Ge islands from Ge layer on Si substrate during post-growth rapid thermal annealing (RTA). The size of the islands decreases from 0.6 to 0.1 as the rapid thermal annealing time increases from 30 s to 60 s at 900 deg. C. Not only that the annealing produces Ge islands but also wetting layer. Energy Dispersive X-ray Spectroscopy (EDX) and Scanning Electron Microscopy (SEM) were employed for structural analysis of Ge islands. Metal-Semiconductor-Metal photodetectors (MSM PDs) were fabricated on Ge islands (and wetting layer)/Si. The Ge islands and wetting layer between the contacts of the fabricated devices are etched in order to see their effects on the device. The performance of the Ge islands MSM-PD was evaluated by dark and photo current-voltage (I-V) measurements at room temperature (RT). It was found that the device with island and wetting layer significantly enhance the current gain (ratio of photo current to dark current) of the device.

  8. Foreword: Focus on Superconductivity in Semiconductors

    Directory of Open Access Journals (Sweden)

    Yoshihiko Takano

    2008-01-01

    Full Text Available Since the discovery of superconductivity in diamond, much attention has been given to the issue of superconductivity in semiconductors. Because diamond has a large band gap of 5.5 eV, it is called a wide-gap semiconductor. Upon heavy boron doping over 3×1020 cm−3, diamond becomes metallic and demonstrates superconductivity at temperatures below 11.4 K. This discovery implies that a semiconductor can become a superconductor upon carrier doping. Recently, superconductivity was also discovered in boron-doped silicon and SiC semiconductors. The number of superconducting semiconductors has increased. In 2008 an Fe-based superconductor was discovered in a research project on carrier doping in a LaCuSeO wide-gap semiconductor. This discovery enhanced research activities in the field of superconductivity, where many scientists place particular importance on superconductivity in semiconductors.This focus issue features a variety of topics on superconductivity in semiconductors selected from the 2nd International Workshop on Superconductivity in Diamond and Related Materials (IWSDRM2008, which was held at the National Institute for Materials Science (NIMS, Tsukuba, Japan in July 2008. The 1st workshop was held in 2005 and was published as a special issue in Science and Technology of Advanced Materials (STAM in 2006 (Takano 2006 Sci. Technol. Adv. Mater. 7 S1.The selection of papers describe many important experimental and theoretical studies on superconductivity in semiconductors. Topics on boron-doped diamond include isotope effects (Ekimov et al and the detailed structure of boron sites, and the relation between superconductivity and disorder induced by boron doping. Regarding other semiconductors, the superconducting properties of silicon and SiC (Kriener et al, Muranaka et al and Yanase et al are discussed, and In2O3 (Makise et al is presented as a new superconducting semiconductor. Iron-based superconductors are presented as a new series of high

  9. Frequency modulation of semiconductor disk laser pulses

    Energy Technology Data Exchange (ETDEWEB)

    Zolotovskii, I O; Korobko, D A; Okhotnikov, O G [Ulyanovsk State University, Ulyanovsk (Russian Federation)

    2015-07-31

    A numerical model is constructed for a semiconductor disk laser mode-locked by a semiconductor saturable absorber mirror (SESAM), and the effect that the phase modulation caused by gain and absorption saturation in the semiconductor has on pulse generation is examined. The results demonstrate that, in a laser cavity with sufficient second-order dispersion, alternating-sign frequency modulation of pulses can be compensated for. We also examine a model for tuning the dispersion in the cavity of a disk laser using a Gires–Tournois interferometer with limited thirdorder dispersion. (control of radiation parameters)

  10. Carrier concentration induced ferromagnetism in semiconductors

    International Nuclear Information System (INIS)

    Story, T.

    2007-01-01

    In semiconductor spintronics the key materials issue concerns ferromagnetic semiconductors that would, in particular, permit an integration (in a single multilayer heterostructure) of standard electronic functions of semiconductors with magnetic memory function. Although classical semiconductor materials, such as Si or GaAs, are nonmagnetic, upon substitutional incorporation of magnetic ions (typically of a few atomic percents of Mn 2+ ions) and very heavy doping with conducting carriers (at the level of 10 20 - 10 21 cm -3 ) a ferromagnetic transition can be induced in such diluted magnetic semiconductors (also known as semimagnetic semiconductors). In the lecture the spectacular experimental observations of carrier concentration induced ferromagnetism will be discussed for three model semiconductor crystals. p - Ga 1-x Mn x As currently the most actively studied and most perspective ferromagnetic semiconductor of III-V group, in which ferromagnetism appears due to Mn ions providing both local magnetic moments and acting as acceptor centers. p - Sn 1-x Mn x Te and p - Ge 1-x Mn x Te classical diluted magnetic semiconductors of IV-VI group, in which paramagnet-ferromagnet and ferromagnet-spin glass transitions are found for very high hole concentration. n - Eu 1-x Gd x Te mixed magnetic crystals, in which the substitution of Gd 3+ ions for Eu 2+ ions creates very high electron concentration and transforms antiferromagnetic EuTe (insulating compound) into ferromagnetic n-type semiconductor alloy. For each of these materials systems the key physical features will be discussed concerning: local magnetic moments formation, magnetic phase diagram as a function of magnetic ions and carrier concentration as well as Curie temperature and magnetic anisotropy engineering. Various theoretical models proposed to explain the effect of carrier concentration induced ferromagnetism in semiconductors will be briefly discussed involving mean field approaches based on Zener and RKKY

  11. Semiconductor quantum-dot lasers and amplifiers

    DEFF Research Database (Denmark)

    Hvam, Jørn Märcher; Borri, Paola; Ledentsov, N. N.

    2002-01-01

    -power surface emitting VCSELs. We investigated the ultrafast dynamics of quantum-dot semiconductor optical amplifiers. The dephasing time at room temperature of the ground-state transition in semiconductor quantum dots is around 250 fs in an unbiased amplifier, decreasing to below 50 fs when the amplifier...... is biased to positive net gain. We have further measured gain recovery times in quantum dot amplifiers that are significantly lower than in bulk and quantum-well semiconductor optical amplifiers. This is promising for future demonstration of quantum dot devices with high modulation bandwidth...

  12. Laser Cooling of 2-6 Semiconductors

    Science.gov (United States)

    2016-08-12

    AFRL-AFOSR-JP-TR-2016-0067 Laser Cooling of II-VI Semiconductors Qihua Xiong NANYANG TECHNOLOGICAL UNIVERSITY Final Report 08/12/2016 DISTRIBUTION A...From - To) 15 May 2013 to 14 May 2016 4. TITLE AND SUBTITLE Laser Cooling of II-VI Semiconductors 5a.  CONTRACT NUMBER 5b.  GRANT NUMBER FA2386-13-1...13. SUPPLEMENTARY NOTES 14. ABSTRACT The breakthrough of laser cooling in semiconductor has stimulated strong interest in further scaling up towards

  13. Diluted magnetic semiconductor nanowires exhibiting magnetoresistance

    Science.gov (United States)

    Yang, Peidong [El Cerrito, CA; Choi, Heonjin [Seoul, KR; Lee, Sangkwon [Daejeon, KR; He, Rongrui [Albany, CA; Zhang, Yanfeng [El Cerrito, CA; Kuykendal, Tevye [Berkeley, CA; Pauzauskie, Peter [Berkeley, CA

    2011-08-23

    A method for is disclosed for fabricating diluted magnetic semiconductor (DMS) nanowires by providing a catalyst-coated substrate and subjecting at least a portion of the substrate to a semiconductor, and dopant via chloride-based vapor transport to synthesize the nanowires. Using this novel chloride-based chemical vapor transport process, single crystalline diluted magnetic semiconductor nanowires Ga.sub.1-xMn.sub.xN (x=0.07) were synthesized. The nanowires, which have diameters of .about.10 nm to 100 nm and lengths of up to tens of micrometers, show ferromagnetism with Curie temperature above room temperature, and magnetoresistance up to 250 Kelvin.

  14. Improvements in or relating to semiconductor devices

    International Nuclear Information System (INIS)

    Cooper, K.; Groves, I.S.; Leigh, P.A.; McIntyre, N.; O'Hara, S.; Speight, J.D.

    1980-01-01

    A method of producing semiconductor devices is described consisting of a series of physical and chemical techniques which results in the production of semiconductor devices such as IMPATT diodes of DC-RF efficiency and high reliability (lifetime). The diodes can be mass produced without significant variation of the technology. One of the techniques used is the high energy proton bombardment of the semiconductor material in depth to passivate specific zones. The energy of the protons is increased in stages at intervals of less than 0.11 MeV up to a predetermined maximum energy. (UK)

  15. OPENING ADDRESS: Heterostructures in Semiconductors

    Science.gov (United States)

    Grimmeiss, Hermann G.

    1996-01-01

    Good morning, Gentlemen! On behalf of the Nobel Foundation, I should like to welcome you to the Nobel Symposium on "Heterostructures in Semiconductors". It gives me great pleasure to see so many colleagues and old friends from all over the world in the audience and, in particular, to bid welcome to our Nobel laureates, Prof. Esaki and Prof. von Klitzing. In front of a different audience I would now commend the scientific and technological importance of heterostructures in semiconductors and emphatically emphasise that heterostructures, as an important contribution to microelectronics and, hence, information technology, have changed societies all over the world. I would also mention that information technology is one of the most important global key industries which covers a wide field of important areas each of which bears its own character. Ever since the invention of the transistor, we have witnessed a fantastic growth in semiconductor technology, leading to more complex functions and higher densities of devices. This development would hardly be possible without an increasing understanding of semiconductor materials and new concepts in material growth techniques which allow the fabrication of previously unknown semiconductor structures. But here and today I will not do it because it would mean to carry coals to Newcastle. I will therefore not remind you that heterostructures were already suggested and discussed in detail a long time before proper technologies were available for the fabrication of such structures. Now, heterostructures are a foundation in science and part of our everyday life. Though this is certainly true, it is nevertheless fair to say that not all properties of heterostructures are yet understood and that further technologies have to be developed before a still better understanding is obtained. The organisers therefore hope that this symposium will contribute not only to improving our understanding of heterostructures but also to opening new

  16. Heron Island, Australia

    Science.gov (United States)

    2002-01-01

    Heron Island is located at the sourthern end of Australia's 2,050 km-long Great Barrier Reef. Surrounded by coral reef and home to over 1000 species of fish, scuba divers and scientists alike are drawn to the island's resort and research station. The true-color image above was taken by Space Imaging's Ikonos satellite with a resolution of 4 meters per pixel-high enough to see individual boats tied up at the small marina. The narrow channel leading from the marina to the ocean was blasted and dredged decades ago, before the island became a national park. Since then the Australian government has implemented conservation measures, such as limiting the number of tourists and removing or recycling, instead of incinerating, all trash. One of the applications of remote sensing data from Ikonos is environmental monitoring, including studies of coral reef health. For more information about the island, read Heron Island. Image by Robert Simmon, based on data copyright Space Imaging

  17. Life-cycle assessment of semiconductors

    CERN Document Server

    Boyd, Sarah B

    2012-01-01

    Life-Cycle Assessment of Semiconductors presents the first and thus far only available transparent and complete life cycle assessment of semiconductor devices. A lack of reliable semiconductor LCA data has been a major challenge to evaluation of the potential environmental benefits of information technologies (IT). The analysis and results presented in this book will allow a higher degree of confidence and certainty in decisions concerning the use of IT in efforts to reduce climate change and other environmental effects. Coverage includes but is not limited to semiconductor manufacturing trends by product type and geography, unique coverage of life-cycle assessment, with a focus on uncertainty and sensitivity analysis of energy and global warming missions for CMOS logic devices, life cycle assessment of flash memory and life cycle assessment of DRAM. The information and conclusions discussed here will be highly relevant and useful to individuals and institutions. The book also: Provides a detailed, complete a...

  18. Semiconductor applications of plasma immersion ion implantation ...

    Indian Academy of Sciences (India)

    Home; Journals; Bulletin of Materials Science; Volume 25; Issue 6. Semiconductor applications of plasma immersion ion implantation technology ... Department of Electronic Science, Kurukshetra University, Kurukshetra 136 119, India ...

  19. Second harmonic spectroscopy of semiconductor nanostructures

    DEFF Research Database (Denmark)

    Østergaard, John Erland; Yu, Ping; Bozhevolnyi, Sergey I.

    1999-01-01

    Semiconductor nanostructures and their application to optoelectronic devices have attracted much attention recently. Lower-dimensional structures, and in particular quantum dots, are highly anisotropic resulting in broken symmetry as compared to their bulk counterparts. This is not only reflected...

  20. 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...

  1. Semiconductors detectors: basics principals, fabrication and repair

    International Nuclear Information System (INIS)

    Souza Coelho, L.F. de.

    1982-05-01

    The fabrication and repairing techniques of semiconductor detectors, are described. These methods are shown in the way they are applied by the semiconductor detector laboratory of the KFA-Julich, where they have been developed during the last 15 years. The history of the semiconductor detectors is presented here, being also described the detector fabrication experiences inside Brazil. The key problems of manufacturing are raised. In order to understand the fabrication and repairing techniques the working principles of these detectors, are described. The cases in which worked during the stay in the KFA-Julich, particularly the fabrication of a plane Ge (Li) detector, with side entry, and the repair of a coaxial Ge (Li) is described. The vanguard problems being researched in Julich are also described. Finally it is discussed a timetable for the semiconductor detector laboratory of the UFRJ, which laboratory is in the mounting stage now. (Author) [pt

  2. 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.

  3. Analysis and simulation of semiconductor devices

    CERN Document Server

    Selberherr, Siegfried

    1984-01-01

    The invention of semiconductor devices is a fairly recent one, considering classical time scales in human life. The bipolar transistor was announced in 1947, and the MOS transistor, in a practically usable manner, was demonstrated in 1960. From these beginnings the semiconductor device field has grown rapidly. The first integrated circuits, which contained just a few devices, became commercially available in the early 1960s. Immediately thereafter an evolution has taken place so that today, less than 25 years later, the manufacture of integrated circuits with over 400.000 devices per single chip is possible. Coincident with the growth in semiconductor device development, the literature concerning semiconductor device and technology issues has literally exploded. In the last decade about 50.000 papers have been published on these subjects. The advent of so called Very-Large-Scale-Integration (VLSI) has certainly revealed the need for a better understanding of basic device behavior. The miniaturization of the s...

  4. Semiconductor-nanocrystal/conjugated polymer thin films

    Science.gov (United States)

    Alivisatos, A. Paul; Dittmer, Janke J.; Huynh, Wendy U.; Milliron, Delia

    2014-06-17

    The invention described herein provides for thin films and methods of making comprising inorganic semiconductor-nanocrystals dispersed in semiconducting-polymers in high loading amounts. The invention also describes photovoltaic devices incorporating the thin films.

  5. Advances in semiconductor photodetectors for scintillators

    International Nuclear Information System (INIS)

    Farrell, R.; Olschner, F.; Shah, K.; Squillante, M.R.

    1997-01-01

    Semiconductors photodetectors have long seemed an attractive alternative for scintillation detection, but only recently have semiconductor photodiodes been proven suitable for some room temperature applications. There are many applications, however for which the performance of standard silicon p-i-n photodiodes is not satisfactory. This article reviews recent progress in two different families of novel semiconductor photodetectors: (1) wide bandgap compound semiconductors and (2) silicon photodetectors with enhanced signal-to-noise ratio. The compounds discussed and compared in this paper are HgI 2 , PbI 2 , InI, TlBr, TlBr 1-x I x and HgBr 1-x I x . The paper will also examine unity gain silicon drift diodes and avalanche photodiodes with maximum room temperature gain greater than 10000. (orig.)

  6. Semiconductor Photonic Components for RF Applications

    National Research Council Canada - National Science Library

    Yu, Paul

    2002-01-01

    ... time delay beam formation and beam steering subsystem in phased array antennas. Device and material approaches were investigated to improve the modulator based on semiconductor structures for achieving high spur free dynamic range (SFDR...

  7. Semiconductor Photonic Components for RF Applications

    National Research Council Canada - National Science Library

    Yu, Paul

    2001-01-01

    ... delay beam formation and beam steering subsystems in phased array antennas. Device and material approaches were investigated to improve the modulator based on semiconductor structures for achieving high spur free dynamic range (SFDR...

  8. Room-temperature ductile inorganic semiconductor

    Science.gov (United States)

    Shi, Xun; Chen, Hongyi; Hao, Feng; Liu, Ruiheng; Wang, Tuo; Qiu, Pengfei; Burkhardt, Ulrich; Grin, Yuri; Chen, Lidong

    2018-05-01

    Ductility is common in metals and metal-based alloys, but is rarely observed in inorganic semiconductors and ceramic insulators. In particular, room-temperature ductile inorganic semiconductors were not known until now. Here, we report an inorganic α-Ag2S semiconductor that exhibits extraordinary metal-like ductility with high plastic deformation strains at room temperature. Analysis of the chemical bonding reveals systems of planes with relatively weak atomic interactions in the crystal structure. In combination with irregularly distributed silver-silver and sulfur-silver bonds due to the silver diffusion, they suppress the cleavage of the material, and thus result in unprecedented ductility. This work opens up the possibility of searching for ductile inorganic semiconductors/ceramics for flexible electronic devices.

  9. 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...

  10. Revenue sharing in semiconductor industry supply chain ...

    Indian Academy of Sciences (India)

    to reduce demand opportunities, inventory needs and production efficiencies, in addition to reducing .... design based on coalition structures in semiconductor supply chain. ..... supplier/contract manufacturer for a product/component category.

  11. Small Island Visitor Attractions

    Directory of Open Access Journals (Sweden)

    Haven Allahar

    2015-03-01

    Full Text Available This article proposes a process framework for developing and managing visitor attractions (VA in small island developing states with Trinidad and Tobago, a two-island state in the Caribbean, as the case study. An extensive literature review was conducted, supported by field observations, individual depth interviews, and small and large focus group meetings. The process framework identified four sets of processes: national policy formulation and legislation; inventory, classification, evaluation, and ranking of VA; general operations management involving project management activities; and site specific activities of development, operations, and maintenance. The value of the framework lies in the fact that no similar framework applicable to small islands was covered in the literature and validation was obtained from a panel of experts and a cross section of tourism stakeholders in Tobago.

  12. Small-signal analysis of granular semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    Varpula, Aapo; Sinkkonen, Juha; Novikov, Sergey, E-mail: aapo.varpula@tkk.f [Department of Micro and Nanosciences, Aalto University, PO Box 13500, FI-00076 Aalto, Espoo (Finland)

    2010-11-01

    The small-signal ac response of granular n-type semiconductors is calculated analytically using the drift-diffusion theory when electronic trapping at grain boundaries is present. An electrical equivalent circuit (EEC) model of a granular n-type semiconductor is presented. The analytical model is verified with numerical simulation performed by SILVACO ATLAS. The agreement between the analytical and numerical results is very good in a broad frequency range at low dc bias voltages.

  13. Small-signal analysis of granular semiconductors

    International Nuclear Information System (INIS)

    Varpula, Aapo; Sinkkonen, Juha; Novikov, Sergey

    2010-01-01

    The small-signal ac response of granular n-type semiconductors is calculated analytically using the drift-diffusion theory when electronic trapping at grain boundaries is present. An electrical equivalent circuit (EEC) model of a granular n-type semiconductor is presented. The analytical model is verified with numerical simulation performed by SILVACO ATLAS. The agreement between the analytical and numerical results is very good in a broad frequency range at low dc bias voltages.

  14. Nitride semiconductor devices fundamentals and applications

    CERN Document Server

    Morkoç, Hadis

    2013-01-01

    This book gives a clear presentation of the necessary basics of semiconductor and device physics and engineering. It introduces readers to fundamental issues that will enable them to follow the latest technological research. It also covers important applications, including LED and lighting, semiconductor lasers, high power switching devices, and detectors. This balanced and up-to-date treatment makes the text an essential educational tool for both advanced students and professionals in the electronics industry.

  15. Gain and Index Dynamics in Semiconductor Lasers

    DEFF Research Database (Denmark)

    Hvam, Jørn Märcher

    Semiconductor optical amplifiers (SOAs) provide ultrafast, i.e. broadband components for optical communication systems. They enter not only as signal generators and amplifiers, but also as nonlinear elements for ultrafast signal processing such as wavelength conversion, switching, and regeneration...... changed character from bulk semiconductor to quantum wells and most recently to quantum dots. By quantum confinement of the carriers, the light-matter interactions can be significantly modified and the optical properties, including dynamics, can be engineered to match the required functionalities...

  16. Semiconductor saturable absorbers for ultrafast THz signals

    DEFF Research Database (Denmark)

    Hoffmann, Matthias C.; Turchinovich, Dmitry

    We demonstrate saturable absorber behavior of n-type semiconductors in the THz frequency range using nonlinear THz spectroscopy. Further, we observe THz pulse shortening and increase of the group refractive index at high field strengths.......We demonstrate saturable absorber behavior of n-type semiconductors in the THz frequency range using nonlinear THz spectroscopy. Further, we observe THz pulse shortening and increase of the group refractive index at high field strengths....

  17. Work on the ATLAS semiconductor tracker barrel

    CERN Multimedia

    Maximilien Brice

    2005-01-01

    Precision work is performed on the semiconductor tracker barrel of the ATLAS experiment. All work on these delicate components must be performed in a clean room so that impurities in the air, such as dust, do not contaminate the detector. The semiconductor tracker will be mounted in the barrel close to the heart of the ATLAS experiment to detect the path of particles produced in proton-proton collisions.

  18. 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.

  19. Semiconductor high-energy radiation scintillation detector

    International Nuclear Information System (INIS)

    Kastalsky, A.; Luryi, S.; Spivak, B.

    2006-01-01

    We propose a new scintillation-type detector in which high-energy radiation generates 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. An important advantage of the proposed detector is its fast response time, about 1 ns, essentially limited only by the recombination time of minority carriers. Notably, the fast response comes without any degradation in brightness. When the scintillator is implemented in a qualified semiconductor material (such as InP or GaAs), the photo-detector and associated circuits can be epitaxially integrated on the scintillator slab and the structure can be stacked-up to achieve virtually any desired absorption capability

  20. Charge regulation at semiconductor-electrolyte interfaces.

    Science.gov (United States)

    Fleharty, Mark E; van Swol, Frank; Petsev, Dimiter N

    2015-07-01

    The interface between a semiconductor material and an electrolyte solution has interesting and complex electrostatic properties. Its behavior will depend on the density of mobile charge carriers that are present in both phases as well as on the surface chemistry at the interface through local charge regulation. The latter is driven by chemical equilibria involving the immobile surface groups and the potential determining ions in the electrolyte solution. All these lead to an electrostatic potential distribution that propagate such that the electrolyte and the semiconductor are dependent on each other. Hence, any variation in the charge density in one phase will lead to a response in the other. This has significant implications on the physical properties of single semiconductor-electrolyte interfaces and on the electrostatic interactions between semiconductor particles suspended in electrolyte solutions. The present paper expands on our previous publication (Fleharty et al., 2014) and offers new results on the electrostatics of single semiconductor interfaces as well as on the interaction of charged semiconductor colloids suspended in electrolyte solution. Copyright © 2014 Elsevier Inc. All rights reserved.

  1. Novel routes to nanodispersed semiconductors

    International Nuclear Information System (INIS)

    Green, M.A.

    1999-01-01

    Novel synthetic routes to nanodispersed compound semiconductors using organometallic precursors have been developed. The quantum dots have been studied by optical absorption spectroscopy, photoluminescence spectroscopy, transmission electron microscopy, high resolution transmission electron microscopy, infra red spectroscopy and nuclear magnetic resonance. Polar Lewis base solvents such as tri-n-octylphosphine oxide and 4-ethylpyridine were utilized as both passivating agent and dispersing medium. In the the search for new solvent systems and passivating agents, and investigation was also made into the use of dimethyl sulfoxide as a reaction solvent and capping agent in the preparation of nanocrystalline CdS. Existing routes using metal alkyls and silylated precursors in hot TOPO were improved by substituting the metal alkyl with an metal alkyl adduct. Cadmium monothiocarbamate and a related precursor, cadmium thioacetate were investigated as possible single source precursors to nanometer sized CdS. The thermolysis of diorganophosphides in the Lewis bases coordinating solvent (4-ethylpridine) has been investigated, including studies of decompositon mechanisms, and quantum dots of Cd 3 P 2 , Zn 3 P 2 , Inp and GaP have been prepared. The synthesis of InAs using the metal chloride and an aminoarsenide precursor in 4-ethylpridine has also been developed. A simple method for the organization of III-V materials into glass like aggregates has been described. (author)

  2. Quantum transport in semiconductor nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Kubis, Tillmann Christoph

    2009-11-15

    The main objective of this thesis is to theoretically predict the stationary charge and spin transport in mesoscopic semiconductor quantum devices in the presence of phonons and device imperfections. It is well known that the nonequilibrium Green's function method (NEGF) is a very general and all-inclusive scheme for the description of exactly this kind of transport problem. Although the NEGF formalism has been derived in the 1960's, textbooks about this formalism are still rare to find. Therefore, we introduce the NEGF formalism, its fundamental equations and approximations in the first part of this thesis. Thereby, we extract ideas of several seminal contributions on NEGF in literature and augment this by some minor derivations that are hard to find. Although the NEGF method has often been numerically implemented on transport problems, all current work in literature is based on a significant number of approximations with often unknown influence on the results and unknown validity limits. Therefore, we avoid most of the common approximations and implement in the second part of this thesis the NEGF formalism as exact as numerically feasible. For this purpose, we derive several new scattering self-energies and introduce new self-adaptive discretizations for the Green's functions and self-energies. The most important improvements of our NEGF implementation, however, affect the momentum and energy conservation during incoherent scattering, the Pauli blocking, the current conservation within and beyond the device and the reflectionless propagation through open device boundaries. Our uncommonly accurate implementation of the NEGF method allows us to analyze and assess most of the common approximations and to unveil numerical artifacts that have plagued previous approximate implementations in literature. Furthermore, we apply our numerical implementation of the NEGF method on the stationary electron transport in THz quantum cascade lasers (QCLs) and answer

  3. Self Organization in Compensated Semiconductors

    Science.gov (United States)

    Berezin, Alexander A.

    2004-03-01

    In partially compensated semiconductor (PCS) Fermi level is pinned to donor sub-band. Due to positional randomness and almost isoenergetic hoppings, donor-spanned electronic subsystem in PCS forms fluid-like highly mobile collective state. This makes PCS playground for pattern formation, self-organization, complexity emergence, electronic neural networks, and perhaps even for origins of life, bioevolution and consciousness. Through effects of impact and/or Auger ionization of donor sites, whole PCS may collapse (spinodal decomposition) into microblocks potentially capable of replication and protobiological activity (DNA analogue). Electronic screening effects may act in RNA fashion by introducing additional length scale(s) to system. Spontaneous quantum computing on charged/neutral sites becomes potential generator of informationally loaded microstructures akin to "Carl Sagan Effect" (hidden messages in Pi in his "Contact") or informational self-organization of "Library of Babel" of J.L. Borges. Even general relativity effects at Planck scale (R.Penrose) may affect the dynamics through (e.g.) isotopic variations of atomic mass and local density (A.A.Berezin, 1992). Thus, PCS can serve as toy model (experimental and computational) at interface of physics and life sciences.

  4. Photoemission studies of semiconductor nanocrystals

    International Nuclear Information System (INIS)

    Hamad, K.S.; Roth, R.; Alivisatos, A.P.

    1997-01-01

    Semiconductor nanocrystals have been the focus of much attention in the last ten years due predominantly to their size dependent optical properties. Namely, the band gap of nanocrystals exhibits a shift to higher energy with decreasing size due to quantum confinement effects. Research in this field has employed primarily optical techniques to study nanocrystals, and in this respect this system has been investigated extensively. In addition, one is able to synthesize monodisperse, crystalline particles of CdS, CdSe, Si, InP, InAs, as well as CdS/HgS/CdS and CdSe/CdS composites. However, optical spectroscopies have proven ambiguous in determining the degree to which electronic excitations are interior or surface admixtures or giving a complete picture of the density of states. Photoemission is a useful technique for understanding the electronic structure of nanocrystals and the effects of quantum confinement, chemical environments of the nanocrystals, and surface coverages. Of particular interest to the authors is the surface composition and structure of these particles, for they have found that much of the behavior of nanocrystals is governed by their surface. Previously, the authors had performed x-ray photoelectron spectroscopy (XPS) on CdSe nanocrystals. XPS has proven to be a powerful tool in that it allows one to determine the composition of the nanocrystal surface

  5. Spin Transport in Semiconductor heterostructures

    International Nuclear Information System (INIS)

    Marinescu, Domnita Catalina

    2011-01-01

    The focus of the research performed under this grant has been the investigation of spin transport in magnetic semiconductor heterostructures. The interest in these systems is motivated both by their intriguing physical properties, as the physical embodiment of a spin-polarized Fermi liquid, as well as by their potential applications as spintronics devices. In our work we have analyzed several different problems that affect the spin dynamics in single and bi-layer spin-polarized two-dimensional (2D) systems. The topics of interests ranged from the fundamental aspects of the electron-electron interactions, to collective spin and charge density excitations and spin transport in the presence of the spin-orbit coupling. The common denominator of these subjects is the impact at the macroscopic scale of the spin-dependent electron-electron interaction, which plays a much more subtle role than in unpolarized electron systems. Our calculations of several measurable parameters, such as the excitation frequencies of magneto-plasma modes, the spin mass, and the spin transresistivity, propose realistic theoretical estimates of the opposite-spin many-body effects, in particular opposite-spin correlations, that can be directly connected with experimental measurements.

  6. Faraday effect in semimagnetic semiconductors

    International Nuclear Information System (INIS)

    Nikitin, P.I.; Savchuk, A.I.

    1990-01-01

    Experimental and theoretical studies of the Faraday effect in a new class of materials -semimagnetic semiconductors (SS) have been received. Mechanisms of the giant Faraday effect in SS based on s, p-d exchange interaction of excitons, electrons and holes with magnetic ions have been discussed. Faraday rotation as a function of a radiation wavelength, magnetic component concentration, temperature, magnetic field intensity for crystals A 2 B 6 (Mn)A 2 x -1Mn xB 6 : and other SS (GaAs(Mn), CdP 2 (Mn),Pb 1-X2 )Mn x J 2 have been considered. We have attended to use FR for the study of a paramagnetic-spin glass transmission for determining the role of the relaxation effects with a participation of magnetic Mn 2+ ions, exitons, polarons in the direct and inverse Faraday effects. In addition the features of FR in thin films of SS and in spin superlattices have been discussed. Finally, we have analysed possibilities of applying the SS Faraday effect for developing magnetooptic devices (optical isolators and fibre optic sensors of magnetic fields)

  7. Island of Luzon, Philippines

    Science.gov (United States)

    1990-01-01

    In this north to south view of the Island of Luzon, Philippines (13.0N, 120.0E), the prominent Cordillera Central mountain range where gold, copper and silver are mined. The several large rivers that drain this region normally carry a heavy silt load to the sea but the absence of sediment plumes in this view is evidence of hot dry weather and lack of recent rains. Manila, the capital city is just visible at the south end of the island.

  8. Chatham Islands Climate Change

    International Nuclear Information System (INIS)

    Mullan, B.; Salinger, J.; Thompson, C.; Ramsay, D.; Wild, M.

    2005-06-01

    This brief report provides guidance on climate change specific to the Chatham Islands, to complement the information recently produced for local government by the Ministry for the Environment in 'Climate Change Effects and Impacts Assessment: A guidance manual for Local Government in New Zealand' and 'Coastal Hazards and Climate Change: A guidance manual for Local Government in New Zealand'. These previous reports contain a lot of generic information on climate change, and how to assess associated risks, that is relevant to the Chatham Islands Council.

  9. Island in the Air

    DEFF Research Database (Denmark)

    Simonsen, Dorthe Gert

    2017-01-01

    In this article, I explore the formation of airspace in Britain from 1910 to 1913. The technology of flight challenged the “flat discourse” of nationalized geography, drawing up instead a volumetric space in the sky as airplanes flew from the Continent to England. The drive to control aerial...... extension of the Island Kingdom, extrapolating its coastal borders into the sky. However, even as Parliament passed the Aerial Navigation Act in 1913, this legal construction of an island in the air could not endure the agency of airplanes. The formation of airspace, I argue, is a history particularly well...

  10. Archaeoastronomy of Easter Island

    Science.gov (United States)

    Edwards, Edmundo

    Astronomer priests or "skywatchers" on Easter Island lived in stone towers that were used as observatories and built stone markers in the periphery that indicated the heliacal rising of certain stars that served to indicate the arrival of marine birds, turtles, the offshore fishing season, and times for planting and harvest. Petroglyphs related to such sites depict outriggers, fishhooks, pelagic fish, and turtles and supposedly represented a star map. In this chapter, we analyze a set of such skywatchers dwellings, and stone markers located upon the North coast of Easter Island that have astronomic orientations, its related petroglyphs, and the relations between these directions with their yearly activities and their ritual calendar.

  11. Long Island Solar Farm

    Energy Technology Data Exchange (ETDEWEB)

    Anders, R.

    2013-05-01

    The Long Island Solar Farm (LISF) is a remarkable success story, whereby very different interest groups found a way to capitalize on unusual circumstances to develop a mutually beneficial source of renewable energy. The uniqueness of the circumstances that were necessary to develop the Long Island Solar Farm make it very difficult to replicate. The project is, however, an unparalleled resource for solar energy research, which will greatly inform large-scale PV solar development in the East. Lastly, the LISF is a superb model for the process by which the project developed and the innovation and leadership shown by the different players.

  12. Plasmonic Control of Radiation and Absorption Processes in Semiconductor Quantum Dots

    Energy Technology Data Exchange (ETDEWEB)

    Paiella, Roberto [Boston Univ., MA (United States); Moustakas, Theodore D. [Boston Univ., MA (United States)

    2017-07-31

    This document reviews a research program funded by the DOE Office of Science, which has been focused on the control of radiation and absorption processes in semiconductor photonic materials (including III-nitride quantum wells and quantum dots), through the use of specially designed metallic nanoparticles (NPs). By virtue of their strongly confined plasmonic resonances (i.e., collective oscillations of the electron gas), these nanostructures can concentrate incident radiation into sub-wavelength “hot spots” of highly enhanced field intensity, thereby increasing optical absorption by suitably positioned absorbers. By reciprocity, the same NPs can also dramatically increase the spontaneous emission rate of radiating dipoles located within their hot spots. The NPs can therefore be used as optical antennas to enhance the radiation output of the underlying active material and at the same time control the far-field pattern of the emitted light. The key accomplishments of the project include the demonstration of highly enhanced light emission efficiency as well as plasmonic collimation and beaming along geometrically tunable directions, using a variety of plasmonic excitations. Initial results showing the reverse functionality (i.e., plasmonic unidirectional absorption and photodetection) have also been generated with similar systems. Furthermore, a new paradigm for the near-field control of light emission has been introduced through rigorous theoretical studies, based on the use of gradient metasurfaces (i.e., optical nanoantenna arrays with spatially varying shape, size, and/or orientation). These activities have been complemented by materials development efforts aimed at the synthesis of suitable light-emitting samples by molecular beam epitaxy. In the course of these efforts, a novel technique for the growth of III-nitride quantum dots has also been developed (droplet heteroepitaxy), with several potential advantages in terms of compositional and geometrical

  13. Islanded operation of distribution networks

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2005-07-01

    This report summarises the results of a study assessing the benefits and risks to distribution network of generator islanding and examining the technical, commercial and regulatory changes required to facilitate the operation of islanding. The background to the study is traced, and details are given of a literature review, the technical criteria for operating sections of the network in islanding mode, and the impact of islanding on trading. Case studies and a detailed implementation plan, data acquisition, and commercial incentives are discussed.

  14. Islanded operation of distribution networks

    International Nuclear Information System (INIS)

    2005-01-01

    This report summarises the results of a study assessing the benefits and risks to distribution network of generator islanding and examining the technical, commercial and regulatory changes required to facilitate the operation of islanding. The background to the study is traced, and details are given of a literature review, the technical criteria for operating sections of the network in islanding mode, and the impact of islanding on trading. Case studies and a detailed implementation plan, data acquisition, and commercial incentives are discussed

  15. Pediatrics in the Marshall Islands

    International Nuclear Information System (INIS)

    Dungy, C.I.; Morgan, B.C.; Adams, W.H.

    1984-01-01

    The delivery of health care to children living on isolated island communities presents unique challenges to health professionals. An evolved method of providing longitudinal services to infants and children residing on islands of the Marshall Island chain - a central Pacific portion of the Micronesian archipelago - is presented. The difficulties associated with provision of comprehensive health care in a vast ocean area are discussed

  16. The Island Smart Energy System and Market

    DEFF Research Database (Denmark)

    Ma, Zheng; Billanes, Joy Dalmacio; Jørgensen, Bo Nørregaard

    2017-01-01

    developing island smart energy systems with the integration of renewable energy resources can increase the energy supply and address the global island energy issues. The island smart energy system operates either in a single-island or in multi-islands. However the island characteristics and influ...

  17. Solomon Islands Botany

    NARCIS (Netherlands)

    Steenis, van C.G.G.J.

    1969-01-01

    A discussion of the Results of the Royal Society Expedition to the British Solomon Islands Protectorate, 1965. Organized by E.J.H. Corner. Phil. Trans. R. Soc. B 255 (1969) 185-631, 196 fig. University Printing House, Shaftesbury Road, Cambridge. Obtainable through booksellers or direct to the Royal

  18. Pacific Island Pharmacovigilance

    DEFF Research Database (Denmark)

    McEwen, John; Vestergaard, Lasse S.; Sanburg, Amanda L C

    2016-01-01

    Many Pacific Island countries (PICs) are recipients of funding support from the Global Fund to Fight AIDS, Tuberculosis and Malaria (Global Fund). However, most of these countries cannot be expected to meet Global Fund and World Health Organization (WHO) minimum requirements for a functioning...

  19. Magnetic-island formation

    International Nuclear Information System (INIS)

    Boozer, A.H.

    1983-08-01

    The response of a finite conductivity plasma to resonant magnetic perturbations is studied. The equations, which are derived for the time development of magnetic islands, help one interpret the singular currents which occur under the assumption of perfect plasma conductivity. The relation to the Rutherford regime of resistive instabilities is given

  20. Bone island and leprosy

    Energy Technology Data Exchange (ETDEWEB)

    Carpintero, P.; Garcia-Frasquet, A. [Department of Orthopaedic Surgery, Cordoba University, Medical School, Reina Sofia University Hospital, Cordoba (Spain); Tarradas, E. [Department of Imaging, Cordoba University, Medical School, Cordoba (Spain); Logrono, C. [Department of Dermatology, Reina Sofia University Hospital, Cordoba (Spain); Carrascal, A. [Department of Radiology, Infanta Elena Hospital, Huelva (Spain); Carreto, A. [Department of Radiology, Reina Sofia University Hospital, Cordoba (Spain)

    1998-06-01

    Objective. To determine the incidence of bone islands in leprosy patients. Design. X-rays of feet and hands of patients with Hansen`s disease (leprosy) were reviewed retrospectively. A second group of related age- and sex-matched patients who did not have Hansen`s disease was used for control purposes. Controls had undergone hand or foot X-rays during diagnosis of other pathologies. The patients with Hansen`s disease were compared with the control group, and were also analyzed as subgroups with different types of leprosy. The results were subjected to statistical analysis. Patients. Ninety patients with Hansen`s disease were randomly selected for this study. Patients who had had ulcers on hands or feet were excluded from the study. Results and conclusions. Bone islands were demonstrated in 20 patients with Hansen`s disease; no bone islands were observed in the controls. This was statistically significant (P<0.01). Bone islands were only seen in patients with lepromatous leprosy and borderline types but were not demonstrated in patients with tuberculoid leprosy. There was also a statistically significant relationship for a disease duration of 15 years or more. The cause of this raised incidence of enostosis in leprosy patients is not clear, but there may be a genetic predisposition in patients with leprosy, or it may be a side effect of leprosy, especially the lepromatous form. (orig.) With 4 figs., 2 tabs., 9 refs.

  1. Bone island and leprosy

    International Nuclear Information System (INIS)

    Carpintero, P.; Garcia-Frasquet, A.; Tarradas, E.; Logrono, C.; Carrascal, A.; Carreto, A.

    1998-01-01

    Objective. To determine the incidence of bone islands in leprosy patients. Design. X-rays of feet and hands of patients with Hansen's disease (leprosy) were reviewed retrospectively. A second group of related age- and sex-matched patients who did not have Hansen's disease was used for control purposes. Controls had undergone hand or foot X-rays during diagnosis of other pathologies. The patients with Hansen's disease were compared with the control group, and were also analyzed as subgroups with different types of leprosy. The results were subjected to statistical analysis. Patients. Ninety patients with Hansen's disease were randomly selected for this study. Patients who had had ulcers on hands or feet were excluded from the study. Results and conclusions. Bone islands were demonstrated in 20 patients with Hansen's disease; no bone islands were observed in the controls. This was statistically significant (P<0.01). Bone islands were only seen in patients with lepromatous leprosy and borderline types but were not demonstrated in patients with tuberculoid leprosy. There was also a statistically significant relationship for a disease duration of 15 years or more. The cause of this raised incidence of enostosis in leprosy patients is not clear, but there may be a genetic predisposition in patients with leprosy, or it may be a side effect of leprosy, especially the lepromatous form. (orig.)

  2. Multidecadal shoreline changes of atoll islands in the Marshall Islands

    Science.gov (United States)

    Ford, M.

    2012-12-01

    Atoll islands are considered highly vulnerable to the impacts of continued sea level rise. One of the most commonly predicted outcomes of continued sea level rise is widespread and chronic shoreline erosion. Despite the widespread implications of predicted erosion, the decadal scale changes of atoll island shorelines are poorly resolved. The Marshall Islands is one of only four countries where the majority of inhabited land is comprised of reef and atoll islands. Consisting of 29 atolls and 5 mid-ocean reef islands, the Marshall Islands are considered highly vulnerable to the impacts of sea level rise. A detailed analysis of shoreline change on over 300 islands on 10 atolls was undertaken using historic aerial photos (1945-1978) and modern high resolution satellite imagery (2004-2012). Results highlight the complex and dynamic nature of atoll islands, with significant shifts in shoreline position observed over the period of analysis. Results suggest shoreline accretion is the dominant mode of change on the islands studied, often associated with a net increase in vegetated island area. However, considerable inter- and intra-atoll variability exists with regards to shoreline stability. Findings are discussed with respect to island morphodynamics and potential hazard mitigation and planning responses within atoll settings.

  3. Disorder phenomena in covalent semiconductors

    International Nuclear Information System (INIS)

    Popescu, M.A.

    1975-01-01

    The structure of the amorphous semiconductors has been investigated by means of X-ray diffraction and by computer simulation of random network models. Amorphous germanium contains mainly five and six-membered rings of atoms. In glassy state, the ternary compounds A 2 B 4 C 2 5 , such as CdGeAs 2 contain only even rings of atoms (six-membered and eight-membered rings). In the memory glasses of the type A 2 B 4 C 2 5 , such as GeAs 2 Te 7 , the valency state of every element is that from the crystal and important van der Waals forces are effective in the network. No Ge-Ge, Ge-As and As-As bonds are formed. The high pressure forms of the germanium have been simulated by computer. The force constants of the covalent bonds in Ge III and Ge IV differ from those in Ge I. The bond bending force constant decreases rapidly when the density of the crystal increases, a fact which has been imparted to a reduction of the sp 3 hybridization. The compressibility curve of the Ge I has been explained. The effect of the radial and uniaxial deformation on the non-crystalline networks has been studied. The compressibility of the amorphous germanium is by 1.5 per cent greater than that of crystalline germanium. The Poisson coefficient for a-Ge network is 0.233. The structure of the As 2 S 3 glass doped with different amounts of germanium (up to 40 at. per cent) and silver (up to 12 at. per cent) has been investigated. The As 2 S 3 Gesub(x) compositions are constituted from a disordered packing of structural units whose chemical composition and relative proportion in the glass essentially depends on the germanium content. (author)

  4. Extracting hot carriers from photoexcited semiconductor nanocrystals

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Xiaoyang

    2014-12-10

    This research program addresses a fundamental question related to the use of nanomaterials in solar energy -- namely, whether semiconductor nanocrystals (NCs) can help surpass the efficiency limits, the so-called “Shockley-Queisser” limit, in conventional solar cells. In these cells, absorption of photons with energies above the semiconductor bandgap generates “hot” charge carriers that quickly “cool” to the band edges before they can be utilized to do work; this sets the solar cell efficiency at a limit of ~31%. If instead, all of the energy of the hot carriers could be captured, solar-to-electric power conversion efficiencies could be increased, theoretically, to as high as 66%. A potential route to capture this energy is to utilize semiconductor nanocrystals. In these materials, the quasi-continuous conduction and valence bands of the bulk semiconductor become discretized due to confinement of the charge carriers. Consequently, the energy spacing between the electronic levels can be much larger than the highest phonon frequency of the lattice, creating a “phonon bottleneck” wherein hot-carrier relaxation is possible via slower multiphonon emission. For example, hot-electron lifetimes as long as ~1 ns have been observed in NCs grown by molecular beam epitaxy. In colloidal NCs, long lifetimes have been demonstrated through careful design of the nanocrystal interfaces. Due to their ability to slow electronic relaxation, semiconductor NCs can in principle enable extraction of hot carriers before they cool to the band edges, leading to more efficient solar cells.

  5. Controlling Molecular Doping in Organic Semiconductors.

    Science.gov (United States)

    Jacobs, Ian E; Moulé, Adam J

    2017-11-01

    The field of organic electronics thrives on the hope of enabling low-cost, solution-processed electronic devices with mechanical, optoelectronic, and chemical properties not available from inorganic semiconductors. A key to the success of these aspirations is the ability to controllably dope organic semiconductors with high spatial resolution. Here, recent progress in molecular doping of organic semiconductors is summarized, with an emphasis on solution-processed p-type doped polymeric semiconductors. Highlighted topics include how solution-processing techniques can control the distribution, diffusion, and density of dopants within the organic semiconductor, and, in turn, affect the electronic properties of the material. Research in these areas has recently intensified, thanks to advances in chemical synthesis, improved understanding of charged states in organic materials, and a focus on relating fabrication techniques to morphology. Significant disorder in these systems, along with complex interactions between doping and film morphology, is often responsible for charge trapping and low doping efficiency. However, the strong coupling between doping, solubility, and morphology can be harnessed to control crystallinity, create doping gradients, and pattern polymers. These breakthroughs suggest a role for molecular doping not only in device function but also in fabrication-applications beyond those directly analogous to inorganic doping. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Selective photochemical dry etching of compound semiconductors

    International Nuclear Information System (INIS)

    Ashby, C.I.H.

    1988-01-01

    When laser-driven etching of a semiconductor requires direct participation of photogenerated carriers, the etching quantum yield will be sensitive to the electronic properties of a specific semiconductor material. The band-gap energy of the semiconductor determines the minimum photon energy needed for carrier-driven etching since sub-gap photons do not generate free carriers. However, only those free carriers that reach the reacting surface contribute to etching and the ultimate carrier flux to the surface is controlled by more subtle electronic properties than the lowest-energy band gap. For example, the initial depth of carrier generation and the probability of carrier recombination between the point of generation and the surface profoundly influence the etching quantum yield. Appropriate manipulation of process parameters can provide additional reaction control based on such secondary electronic properties. Applications to selective dry etching of GaAs and related materials are discussed

  7. Positron annihilation and Wheeler complexes in semiconductors

    International Nuclear Information System (INIS)

    Prokop'ev, E.P.

    1995-01-01

    Properties of Ps-Ex (positron-exciton) complex nature Wheeler complexes that may be formed at irradiation of semiconductors and ion crystals by positrons at low temperature under conditions of optical excitation by excitons are studied. Binding energy of similar and more complex systems regarding decomposition in Ps and Ex and/or Ex ± exceeds, at least, 0.1 eV, while lifetime regarding biquantum-self-annihilation constitutes τ 2γ ∼5.02x10 - 10 κ c 3 c (κ c -phenomenological parameter of the effective mass method). The lifetime estimations enabled to conclude that Ps-Ex complexes may be detected in some oxide semiconductors, in zinc sulfide, as well as, in alkaline-haloid crystals. At the same time, in silicon, gallium arsenide and in other semiconductors of A 3 B 5 and A 2 B 6 it is highly improbable to observe these complexes. 27 refs

  8. Charged Semiconductor Defects Structure, Thermodynamics and Diffusion

    CERN Document Server

    Seebauer, Edmund G

    2009-01-01

    The technologically useful properties of a solid often depend upon the types and concentrations of the defects it contains. Not surprisingly, defects in semiconductors have been studied for many years, in many cases with a view towards controlling their behavior through various forms of "defect engineering." For example, in the bulk, charging significantly affects the total concentration of defects that are available to mediate phenomena such as solid-state diffusion. Surface defects play an important role in mediating surface mass transport during high temperature processing steps such as epitaxial film deposition, diffusional smoothing in reflow, and nanostructure formation in memory device fabrication. Charged Semiconductor Defects details the current state of knowledge regarding the properties of the ionized defects that can affect the behavior of advanced transistors, photo-active devices, catalysts, and sensors. Features: Group IV, III-V, and oxide semiconductors; Intrinsic and extrinsic defects; and, P...

  9. Fabrication and application of amorphous semiconductor devices

    International Nuclear Information System (INIS)

    Kumurdjian, Pierre.

    1976-01-01

    This invention concerns the design and manufacture of elecric switching or memorisation components with amorphous semiconductors. As is known some compounds, particularly the chalcogenides, have a resistivity of the semiconductor type in the amorphous solid state. These materials are obtained by the high temperature homogeneisation of several single elements such as tellurium, arsenic, germanium and sulphur, followed by water or air quenching. In particular these compounds have useful switching and memorisation properties. In particular they have the characteristic of not suffering deterioration when placed in an environment subjected to nuclear radiations. In order to know more about the nature and properties of these amorphous semiconductors the French patent No. 71 28048 of 30 June 1971 may be consulted with advantage [fr

  10. Long wave polar modes in semiconductor heterostructures

    CERN Document Server

    Trallero-Giner, C; García-Moliner, F; Garc A-Moliner, F; Perez-Alvarez, R; Garcia-Moliner, F

    1998-01-01

    Long Wave Polar Modes in Semiconductor Heterostructures is concerned with the study of polar optical modes in semiconductor heterostructures from a phenomenological approach and aims to simplify the model of lattice dynamics calculations. The book provides useful tools for performing calculations relevant to anyone who might be interested in practical applications. The main focus of Long Wave Polar Modes in Semiconductor Heterostructures is planar heterostructures (quantum wells or barriers, superlattices, double barrier structures etc) but there is also discussion on the growing field of quantum wires and dots. Also to allow anyone reading the book to apply the techniques discussed for planar heterostructures, the scope has been widened to include cylindrical and spherical geometries. The book is intended as an introductory text which guides the reader through basic questions and expands to cover state-of-the-art professional topics. The book is relevant to experimentalists wanting an instructive presentatio...

  11. Slow and fast light in semiconductor waveguides

    DEFF Research Database (Denmark)

    Mørk, Jesper; Hansen, Per Lunnemann; Xue, Weiqi

    2010-01-01

    Investigations of slow and fast light effects in semiconductor waveguides entail interesting physics and point to a number of promising applications. In this review we give an overview of recent progress in the field, in particular focusing on the physical mechanisms of electromagnetically induced...... transparency and coherent population oscillations. While electromagnetically induced transparency has been the most important effect in realizing slowdown effects in atomic gasses, progress has been comparatively slow in semiconductors due to inherent problems of fast dephasing times and inhomogeneous...... broadening in quantum dots. The physics of electromagnetically induced transparency in semiconductors is discussed, emphasizing these limitations and recent suggestions for overcoming them. On the other hand, the mechanism of coherent population oscillations relies on wave mixing effects and is well suited...

  12. 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...

  13. 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 ...

  14. Hybrid system of semiconductor and photosynthetic protein

    International Nuclear Information System (INIS)

    Kim, Younghye; Shin, Seon Ae; Lee, Jaehun; Yang, Ki Dong; Nam, Ki Tae

    2014-01-01

    Photosynthetic protein has the potential to be a new attractive material for solar energy absorption and conversion. The development of semiconductor/photosynthetic protein hybrids is an example of recent progress toward efficient, clean and nanostructured photoelectric systems. In the review, two biohybrid systems interacting through different communicating methods are addressed: (1) a photosynthetic protein immobilized semiconductor electrode operating via electron transfer and (2) a hybrid of semiconductor quantum dots and photosynthetic protein operating via energy transfer. The proper selection of materials and functional and structural modification of the components and optimal conjugation between them are the main issues discussed in the review. In conclusion, we propose the direction of future biohybrid systems for solar energy conversion systems, optical biosensors and photoelectric devices. (topical reviews)

  15. Semiconductor laser using multimode interference principle

    Science.gov (United States)

    Gong, Zisu; Yin, Rui; Ji, Wei; Wu, Chonghao

    2018-01-01

    Multimode interference (MMI) structure is introduced in semiconductor laser used in optical communication system to realize higher power and better temperature tolerance. Using beam propagation method (BPM), Multimode interference laser diode (MMI-LD) is designed and fabricated in InGaAsP/InP based material. As a comparison, conventional semiconductor laser using straight single-mode waveguide is also fabricated in the same wafer. With a low injection current (about 230 mA), the output power of the implemented MMI-LD is up to 2.296 mW which is about four times higher than the output power of the conventional semiconductor laser. The implemented MMI-LD exhibits stable output operating at the wavelength of 1.52 μm and better temperature tolerance when the temperature varies from 283.15 K to 293.15 K.

  16. Developing New Nanoprobes from Semiconductor Nanocrystals

    Energy Technology Data Exchange (ETDEWEB)

    Fu, Aihua [Univ. of California, Berkeley, CA (United States)

    2006-01-01

    In recent years, semiconductor nanocrystal quantum dots havegarnered the spotlight as an important new class of biological labelingtool. Withoptical properties superior to conventional organicfluorophores from many aspects, such as high photostability andmultiplexing capability, quantum dots have been applied in a variety ofadvanced imaging applications. This dissertation research goes along withlarge amount of research efforts in this field, while focusing on thedesign and development of new nanoprobes from semiconductor nanocrystalsthat are aimed for useful imaging or sensing applications not possiblewith quantum dots alone. Specifically speaking, two strategies have beenapplied. In one, we have taken advantage of the increasing capability ofmanipulating the shape of semiconductor nanocrystals by developingsemiconductor quantum rods as fluorescent biological labels. In theother, we have assembled quantum dots and gold nanocrystals into discretenanostructures using DNA. The background information and synthesis,surface manipulation, property characterization and applications of thesenew nanoprobes in a few biological experiments are detailed in thedissertation.

  17. Optical Biosensors Based on Semiconductor Nanostructures

    Directory of Open Access Journals (Sweden)

    Raúl J. Martín-Palma

    2009-06-01

    Full Text Available The increasing availability of semiconductor-based nanostructures with novel and unique properties has sparked widespread interest in their use in the field of biosensing. The precise control over the size, shape and composition of these nanostructures leads to the accurate control of their physico-chemical properties and overall behavior. Furthermore, modifications can be made to the nanostructures to better suit their integration with biological systems, leading to such interesting properties as enhanced aqueous solubility, biocompatibility or bio-recognition. In the present work, the most significant applications of semiconductor nanostructures in the field of optical biosensing will be reviewed. In particular, the use of quantum dots as fluorescent bioprobes, which is the most widely used application, will be discussed. In addition, the use of some other nanometric structures in the field of biosensing, including porous semiconductors and photonic crystals, will be presented.

  18. Reliability and radiation effects in compound semiconductors

    CERN Document Server

    Johnston, Allan

    2010-01-01

    This book discusses reliability and radiation effects in compound semiconductors, which have evolved rapidly during the last 15 years. Johnston's perspective in the book focuses on high-reliability applications in space, but his discussion of reliability is applicable to high reliability terrestrial applications as well. The book is important because there are new reliability mechanisms present in compound semiconductors that have produced a great deal of confusion. They are complex, and appear to be major stumbling blocks in the application of these types of devices. Many of the reliability problems that were prominent research topics five to ten years ago have been solved, and the reliability of many of these devices has been improved to the level where they can be used for ten years or more with low failure rates. There is also considerable confusion about the way that space radiation affects compound semiconductors. Some optoelectronic devices are so sensitive to damage in space that they are very difficu...

  19. X-ray characterization of Ge dots epitaxially grown on nanostructured Si islands on silicon-on-insulator substrates.

    Science.gov (United States)

    Zaumseil, Peter; Kozlowski, Grzegorz; Yamamoto, Yuji; Schubert, Markus Andreas; Schroeder, Thomas

    2013-08-01

    On the way to integrate lattice mismatched semiconductors on Si(001), the Ge/Si heterosystem was used as a case study for the concept of compliant substrate effects that offer the vision to be able to integrate defect-free alternative semiconductor structures on Si. Ge nanoclusters were selectively grown by chemical vapour deposition on Si nano-islands on silicon-on-insulator (SOI) substrates. The strain states of Ge clusters and Si islands were measured by grazing-incidence diffraction using a laboratory-based X-ray diffraction technique. A tensile strain of up to 0.5% was detected in the Si islands after direct Ge deposition. Using a thin (∼10 nm) SiGe buffer layer between Si and Ge the tensile strain increases to 1.8%. Transmission electron microscopy studies confirm the absence of a regular grid of misfit dislocations in such structures. This clear experimental evidence for the compliance of Si nano-islands on SOI substrates opens a new integration concept that is not only limited to Ge but also extendable to semiconductors like III-V and II-VI materials.

  20. Island solution; Inselloesung

    Energy Technology Data Exchange (ETDEWEB)

    Bah, Isaac

    2013-06-15

    On the Azores island Graciosa the Berlin-based company Younicos has installed a new electricity system with advanced storage technology, which will make the islanders independent from fossil fuels. With an energy mix of wind power, photovoltaics and biomass the dependence on fossil fuels should be terminated. In the center of the flagship project specifically developed hybrid batteries are used (combination of sodium-sulfur- and lithium-ion batteries) with 2.7 MW of power and a storage capacity of ten megawatts hours. [German] Auf der Azoren-Insel Graciosa installiert das Berliner Unternehmen Younicos ein neues Stromsystem mit modernster Speichertechnologie, das die Bewohner unabhaengig von fossilen Energietraegern machen soll. Mit einem Energiemix aus Windkraft, Photovoltaik und Biomasse soll die Abhaengigkeit von fossilen Brennstoffen beendet werden. Im Zentrum des Vorzeigeprojekts stehen speziell fuer den Inseleinsatz entwickelte Hybridbatterien (Kombination aus Natrium-Schwefel- und Lithium-Ionen-Akkus) mit 2,7 Megawatt Leistung und eine Speicherkapazitaet von zehn Megawattestunden.

  1. Urban heat island 1

    DEFF Research Database (Denmark)

    Bühler, Oliver; Jensen, Marina Bergen; Petersen, Karen Sejr

    2010-01-01

    Urban Heat Island beskriver det forhold, at temperaturen i byområder er højere end temperaturen i tilgrænsede landområder. Årsagen hertil ligger i den urbane arealanvendelse, hvor en mindre andel af arealerne er dækket af vegetation, og en større andel består af forseglede arealer.......Urban Heat Island beskriver det forhold, at temperaturen i byområder er højere end temperaturen i tilgrænsede landområder. Årsagen hertil ligger i den urbane arealanvendelse, hvor en mindre andel af arealerne er dækket af vegetation, og en større andel består af forseglede arealer....

  2. Monolithic integrated photoreceiver for 1.3--1.55-μm wavelengths: Association of a Schottky photodiode and a field-effect transistor on GaInP-GaInAs heteroepitaxy

    International Nuclear Information System (INIS)

    Therani, A.H.; Decoster, D.; Vilcot, J.P.; Razeghi, M.

    1988-01-01

    We present a monolithic integrated circuit associating a Schottky photodiode and a field-effect transistor which has been fabricated, for the first time, on Ga/sub 0.49/In/sub 0.51/P/Ga/sub 0.47/In/sub 0.53/As strained heteroepitaxial material. Static, dynamic, and noise properties of the Schottky photodiode, the field-effect transistor, and the integrated circuit have been investigated and are reported. As an example, dynamic responsivity up to 50 A/W can be achieved at 1.3-μm wavelength for the integrated photoreceiver. The performance of the device is discussed, taking into account the integrated circuit design and the main characteristics of the material

  3. Temperature dependent electronic conduction in semiconductors

    International Nuclear Information System (INIS)

    Roberts, G.G.; Munn, R.W.

    1980-01-01

    This review describes the temperature dependence of bulk-controlled electronic currents in semiconductors. The scope of the article is wide in that it contrasts conduction mechanisms in inorganic and organic solids and also single crystal and disordered semiconductors. In many experimental situations it is the metal-semiconductor contact or the interface between two dissimilar semiconductors that governs the temperature dependence of the conductivity. However, in order to keep the length of the review within reasonable bounds, these topics have been largely avoided and emphasis is therefore placed on bulk-limited currents. A central feature of electronic conduction in semiconductors is the concentrations of mobile electrons and holes that contribute to the conductivity. Various statistical approaches may be used to calculate these densities which are normally strongly temperature dependent. Section 1 emphasizes the relationship between the position of the Fermi level, the distribution of quantum states, the total number of electrons available and the absolute temperature of the system. The inclusion of experimental data for several materials is designed to assist the experimentalist in his interpretation of activation energy curves. Sections 2 and 3 refer to electronic conduction in disordered solids and molecular crystals, respectively. In these cases alternative approaches to the conventional band theory approach must be considered. For example, the velocities of the charge carriers are usually substantially lower than those in conventional inorganic single crystal semiconductors, thus introducing the possibility of an activated mobility. Some general electronic properties of these materials are given in the introduction to each of these sections and these help to set the conduction mechanisms in context. (orig.)

  4. Blasting detonators incorporating semiconductor bridge technology

    Energy Technology Data Exchange (ETDEWEB)

    Bickes, R.W. Jr.

    1994-05-01

    The enormity of the coal mine and extraction industries in Russia and the obvious need in both Russia and the US for cost savings and enhanced safety in those industries suggests that joint studies and research would be of mutual benefit. The author suggests that mine sites and well platforms in Russia offer an excellent opportunity for the testing of Sandia`s precise time-delay semiconductor bridge detonators, with the potential for commercialization of the detonators for Russian and other world markets by both US and Russian companies. Sandia`s semiconductor bridge is generating interest among the blasting, mining and perforation industries. The semiconductor bridge is approximately 100 microns long, 380 microns wide and 2 microns thick. The input energy required for semiconductor bridge ignition is one-tenth the energy required for conventional bridgewire devices. Because semiconductor bridge processing is compatible with other microcircuit processing, timing and logic circuits can be incorporated onto the chip with the bridge. These circuits can provide for the precise timing demanded for cast effecting blasting. Indeed tests by Martin Marietta and computer studies by Sandia have shown that such precise timing provides for more uniform rock fragmentation, less fly rock, reduce4d ground shock, fewer ground contaminants and less dust. Cost studies have revealed that the use of precisely timed semiconductor bridges can provide a savings of $200,000 per site per year. In addition to Russia`s vast mineral resources, the Russian Mining Institute outside Moscow has had significant programs in rock fragmentation for many years. He anticipated that collaborative studies by the Institute and Sandia`s modellers would be a valuable resource for field studies.

  5. Charge Islands Through Tunneling

    Science.gov (United States)

    Robinson, Daryl C.

    2002-01-01

    It has been recently reported that the electrical charge in a semiconductive carbon nanotube is not evenly distributed, but rather it is divided into charge "islands." This paper links the aforementioned phenomenon to tunneling and provides further insight into the higher rate of tunneling processes, which makes tunneling devices attractive. This paper also provides a basis for calculating the charge profile over the length of the tube so that nanoscale devices' conductive properties may be fully exploited.

  6. Islands in the Ocean

    Directory of Open Access Journals (Sweden)

    Elena Bagina

    2017-12-01

    Full Text Available Today’s China is an outpost of modern western architecture. All famous architects and firms build here. Having lost their historical context, the objects of traditional Chinese architecture become islands in the ocean of new development. Their destiny is controversial. Architectural masterpieces are perceived in a superficial manner not only by tourists, but also by local people. The link of times that used to be cherished in Chinese culture is being broken today.

  7. Semiconductor saturable absorbers for ultrafast terahertz signals

    DEFF Research Database (Denmark)

    Hoffmann, Matthias C.; Turchinovich, Dmitry

    2010-01-01

    states, due to conduction band onparabolicity and scattering into satellite valleys in strong THz fields. Saturable absorber parameters, such as linear and nonsaturable transmission, and saturation fluence, are extracted by fits to a classic saturable absorber model. Further, we observe THz pulse......We demonstrate saturable absorber behavior of n-type semiconductors GaAs, GaP, and Ge in the terahertz THz frequency range at room temperature using nonlinear THz spectroscopy. The saturation mechanism is based on a decrease in electron conductivity of semiconductors at high electron momentum...

  8. α-particle shielding of semiconductor device

    International Nuclear Information System (INIS)

    McKeown, P.J.A.; Perry, J.P.; Waddell, J.M.; Barker, K.D.

    1981-01-01

    Soft errors in semiconductor devices, e.g. random access memories, arising from the bombardment of the device by alpha particles produced by the disintegration of minute traces of uranium or thorium in the packaging materials are prevented by coating the active surface of the semiconductor chip with a thin layer, e.g. 20 to 100 microns of an organic polymeric material, this layer being of sufficient thickness to absorb the particles. Typically, the polymer is a poly-imide formed by u.v. electron-beam or thermal curing of liquid monomer applied to the chip surface. (author)

  9. Optically induced Hall effect in semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    Idrish Miah, M; Gray, E Mac A, E-mail: m.miah@griffith.edu.a [Nanoscale Science and Technology Centre, Griffith University, Nathan, Brisbane, QLD 4111 (Australia)

    2009-03-01

    We describe an experiment which investigates the effect of a longitudinal electric field on the spin-polarized carriers generated by a circularly polarized light in semiconductors. Our experiment observes the effect as a Hall voltage resulting from nonequilibrium magnetization induced by the spin-carrier electrons accumulating at the transverse boundaries of the sample as a result of asymmetries in scattering for spin-up and spin-down electrons in the presence of spin-orbit interaction. It is found that the effect depends on the longitudinal electric field and doping density as well as on temperature. The results are presented by discussing the dominant spin relaxation mechanisms in semiconductors.

  10. Ion implantation in semiconductors and other materials

    International Nuclear Information System (INIS)

    Guernet, G.; Bruel, M.; Gailliard, J.P.; Garcia, M.; Robic, J.Y.

    1977-01-01

    The evolution of ion implantation techniques in the field of semiconductors and its extension to various fields such as metallurgy, mechanics, superconductivity and opto-electronics are considered. As for semiconductors ion implantation is evoked as: a means of predeposition of impurities at low doping level (10 11 to 10 14 cm -2 ); a means for obtaining profiles of controlled concentration; a means of reaching high doping levels with using 'strong current' implantation machines of the second generation. Some results obtained are presented [fr

  11. Effect of gain nonlinearity in semiconductor lasers

    DEFF Research Database (Denmark)

    Jensen, Niels H.; Christiansen, Peter Leth; Skovgaard, Ove

    1988-01-01

    Semiconductor lasers are modeled by single-mode rate equations with Langevin noise terms and the influence of nonlinear gain is investigated. For cw operation the probability distribution for the carrier number and the photon number in the laser cavity is obtained. The corresponding (2+1)-dimensi......Semiconductor lasers are modeled by single-mode rate equations with Langevin noise terms and the influence of nonlinear gain is investigated. For cw operation the probability distribution for the carrier number and the photon number in the laser cavity is obtained. The corresponding (2...

  12. Optical Regeneration and Noise in Semiconductor Devices

    DEFF Research Database (Denmark)

    Öhman, Filip

    2005-01-01

    In this report all-optical 2R-regeneration in optical communication systems is investigated. A simple regenerator device based on concatenated semiconductor optical amplifiers (SOAs) and electro absorbers (EAs) is introduced and examined. Experiments show that the monolithic SOA-EA 2R-regenerator......In this report all-optical 2R-regeneration in optical communication systems is investigated. A simple regenerator device based on concatenated semiconductor optical amplifiers (SOAs) and electro absorbers (EAs) is introduced and examined. Experiments show that the monolithic SOA-EA 2R...

  13. Reduced filamentation in high power semiconductor lasers

    DEFF Research Database (Denmark)

    Skovgaard, Peter M. W.; McInerney, John; O'Brien, Peter

    1999-01-01

    High brightness semiconductor lasers have applications in fields ranging from material processing to medicine. The main difficulty associated with high brightness is that high optical power densities cause damage to the laser facet and thus require large apertures. This, in turn, results in spatio......-temporal instabilities such as filamentation which degrades spatial coherence and brightness. We first evaluate performance of existing designs with a “top-hat” shaped transverse current density profile. The unstable nature of highly excited semiconductor material results in a run-away process where small modulations...

  14. Offshoring in the Semiconductor Industry: Historical Perspectives

    OpenAIRE

    Brown, Clair; Linden, Greg

    2005-01-01

    Semiconductor design is a frequently-cited example of the new wave of offshoring and foreign-outsourcing of service sector jobs. It is certainly a concern to U.S. design engineers themselves. In addition to the current wave of white-collar outsourcing, the industry also has a rich experience with offshoring of manufacturing activity. Semiconductor companies were among the first to invest in offshore facilities to manufacture goods for imports back to the U.S. A brief review of these earlie...

  15. Cryogenic semiconductor high-intensity radiation monitors

    International Nuclear Information System (INIS)

    Palmieri, V.G.; Bell, W.H.; Borer, K.; Casagrande, L.; Da Via, C.; Devine, S.R.H.; Dezillie, B.; Esposito, A.; Granata, V.; Hauler, F.; Jungermann, L.; Li, Z.; Lourenco, C.; Niinikoski, T.O.; Shea, V. O'; Ruggiero, G.; Sonderegger, P.

    2003-01-01

    This paper describes a novel technique to monitor high-intensity particle beams by means of a semiconductor detector. It consists of cooling a semiconductor detector down to cryogenic temperature to suppress the thermally generated leakage current and to precisely measure the integrated ionization signal. It will be shown that such a device provides very good linearity and a dynamic range wider than is possible with existing techniques. Moreover, thanks to the Lazarus effect, extreme radiation hardness can be achieved providing in turn absolute intensity measurements against precise calibration of the device at low beam flux

  16. Solid state semiconductor detectorized survey meter

    International Nuclear Information System (INIS)

    Okamoto, Eisuke; Nagase, Yoshiyuki; Furuhashi, Masato

    1987-01-01

    Survey meters are used for measurement of gamma ray dose rate of the space and the surface contamination dencity that the atomic energy plant and the radiation facility etc. We have recently developed semiconductor type survey meter (Commercial name: Compact Survey Meter). This survey meter is a small-sized dose rate meter with excellent function. The special features are using semiconductor type detector which we have developed by our own technique, stablar wide range than the old type, long life, and easy to carry. Now we introduce the efficiency and the function of the survey meter. (author)

  17. Laser vapor phase deposition of semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    Karlov, N.V.; Luk' ianchuk, B.S.; Sisakian, E.V.; Shafeev, G.A.

    1987-06-01

    The pyrolytic effect of IR laser radiation is investigated with reference to the initiation and control of the vapor phase deposition of semiconductor films. By selecting the gas mixture composition and laser emission parameters, it is possible to control the deposition and crystal formation processes on the surface of semiconductors, with the main control action achieved due to the nonadiabatic kinetics of reactions in the gas phase and high temperatures in the laser heating zone. This control mechanism is demonstrated experimentally during the laser vapor deposition of germanium and silicon films from tetrachlorides on single-crystal Si and Ge substrates. 5 references.

  18. 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.

  19. Ion implantation methods for semiconductor substrates

    International Nuclear Information System (INIS)

    Matsushita, T.; Mamine, T.; Hayashi, H.; Nishiyama, K.

    1980-01-01

    A method of ion implantation for controlling the life time of minority carriers in a semiconductor substrate and hence to reduce the temperature dependency of the life time, comprises implanting iron ions into an N type semiconductor substrate with a dosage of 10 10 to 10 15 ions cm -2 , and then heat-treating the implanted substrate at 850 0 to 1250 0 C. The method is applicable to the production of diodes, transistors, Si controlled rectifiers and gate controlled switching devices. (author)

  20. Electroplated Ni on the PN Junction Semiconductor

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-05-15

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

  1. Electroplated Ni on the PN Junction Semiconductor

    International Nuclear Information System (INIS)

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

    2015-01-01

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

  2. Some aspects of ion implantation in semiconductors

    International Nuclear Information System (INIS)

    Klose, H.

    1982-01-01

    The advantages and disadvantages of ion implantation in the application of semiconductor technology are reviewed in short. This article describes some aspects of the state of the art and current developments of nonconventional annealing procedures, ion beam gettering of deep impurities, special applications of ion implantation using low or high energy ions and GaAs-electronics, respectively. Radiation defects in Si and the nonexponential emission and capture processes in GaAsP are discussed. Final future trends of ion beam methods in semiconductor production technology are summarized. (author)

  3. Carrier scattering in metals and semiconductors

    CERN Document Server

    Gantmakher, VF

    1987-01-01

    The transport properties of solids, as well as the many optical phenomena in them are determined by the scattering of current carriers. ``Carrier Scattering in Metals and Semiconductors'' elucidates the state of the art in the research on the scattering mechanisms for current carriers in metals and semiconductors and describes experiments in which these mechanisms are most dramatically manifested.The selection and organization of the material is in a form to prepare the reader to reason independently and to deal just as independently with available theoretical results and experimental

  4. Surface passivation process of compound semiconductor material using UV photosulfidation

    Science.gov (United States)

    Ashby, Carol I. H.

    1995-01-01

    A method for passivating compound semiconductor surfaces by photolytically disrupting molecular sulfur vapor with ultraviolet radiation to form reactive sulfur which then reacts with and passivates the surface of compound semiconductors.

  5. Modeling High Frequency Semiconductor Devices Using Maxwell's Equations

    National Research Council Canada - National Science Library

    El-Ghazaly, Samier

    1999-01-01

    .... In this research, we first replaced the conventional semiconductor device models, which are based on Poisson's Equation as a semiconductor model, with a new one that uses the full-wave electro...

  6. Semiconductor plasmonic crystals : active control of THz extinction

    NARCIS (Netherlands)

    Schaafsma, M.C.; Gomez Rivas, J.

    2013-01-01

    We investigate theoretically the enhanced THz extinction by periodic arrays of semiconductor particles. Scattering particles of doped semiconductors can sustain localized surface plasmon polaritons, which can be diffractively coupled giving rise to surface lattice resonances. These resonances are

  7. Structures and electronics of buried and unburied semiconductor interfaces

    International Nuclear Information System (INIS)

    Kamiya, Itaru

    2011-01-01

    The structure of interfaces plays an important role in determining the electronic properties of semiconductor nanostructures. Here, such examples are shown and discussed using semiconductor nanostructures prepared by molecular beam epitaxy and colloidal synthesis.

  8. Near-infrared light emitting device using semiconductor nanocrystals

    Energy Technology Data Exchange (ETDEWEB)

    Supran, Geoffrey J.S.; Song, Katherine W.; Hwang, Gyuweon; Correa, Raoul Emile; Shirasaki, Yasuhiro; Bawendi, Moungi G.; Bulovic, Vladimir; Scherer, Jennifer

    2018-04-03

    A near-infrared light emitting device can include semiconductor nanocrystals that emit at wavelengths beyond 1 .mu.m. The semiconductor nanocrystals can include a core and an overcoating on a surface of the core.

  9. Elementary steps in electrical doping of organic semiconductors

    KAUST Repository

    Tietze, Max Lutz; Benduhn, Johannes; Pahner, Paul; Nell, Bernhard; Schwarze, Martin; Kleemann, Hans; Krammer, Markus; Zojer, Karin; Vandewal, Koen; Leo, Karl

    2018-01-01

    Fermi level control by doping is established since decades in inorganic semiconductors and has been successfully introduced in organic semiconductors. Despite its commercial success in the multi-billion OLED display business, molecular doping

  10. Progress in semiconductor laser diodes: SPIE volume 723

    International Nuclear Information System (INIS)

    Eichen, E.

    1987-01-01

    This book contains proceedings arranged under the following session headings: High power diode lasers; single emitters and arrays; Ultrahigh speed modulation of semiconductor diode lasers; Coherence and linewidth stabilized semiconductor lasers; and Growth, fabrication, and evaluation of laser diodes

  11. MARICULTURE ON CROATIAN ISLANDS

    Directory of Open Access Journals (Sweden)

    Gordana Šarušić

    2000-09-01

    Full Text Available The first attempts of intensive mariculture in Croatia commenced at the very beginning of 1980’s. The mid-eighties brought an expansion of mariculture production, which has been continuously increasing. A few different marine organisms are intensively cultured - both fish and shellfish. Among them commercially most important and highly valued species are sea bass Dicentrarchus labrax and sea bream Sparus aurata. Mussel Mytilus galloprovincialis and oyster Ostrea edulis are the most important shellfish. Fish species such as dentex Dentex dentex, red sea bream Pagrus major and sheepshead bream Puntazzo puntazzo are reared too, but in a rather small quantities. Only recently the rearing, on-growing- of bluefin tuna Thunnus thynnus started in Croatia. The juveniles (70% are reared in a Croatian hatcheries, and 30% has to be imported mainly from Italy and France, due to a higher demand for this kind of culture among the small growers. Croatian part of Adriatic sea possesses a number of geomorfologicaly suitable sites and meteorological conditions which determined the choice - type - of intensive culture. All fish species are reared in a floating cages. The choice of cages i. e. semi off-shore or floating frames, size, rearing volume and design depend on the investors personal preference. The annual turnouf of a market size bass was about 600t and 300t bream in 1996., by 10 island farms which is 70% of total production in Croatia. Including other cultured fish species last year production was up to 1000t, and it™s being estimated to be about 1300t in the following year. The shellfish production on the islands is usually individual attempt of farmers, producing minor quantities mostly in polyculture. This production has bigger potential but it’s limited owing to the EU quality control regulations which do not allow the export, and by domestic market which has drastically decreased due to the collapse of tourism during the recent war. Almost 80

  12. Optical properties of single semiconductor nanowires and nanowire ensembles. Probing surface physics by photoluminescence spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Pfueller, Carsten

    2011-06-27

    This thesis presents a detailed investigation of the optical properties of semiconductor nanowires (NWs) in general and single GaN NWs and GaN NW ensembles in particular by photoluminescence (PL) spectroscopy. NWs are often considered as potential building blocks for future nanometer-scaled devices. This vision is based on several attractive features that are generally ascribed to NWs. For instance, they are expected to grow virtually free of strain and defects even on substrates with a large structural mismatch. In the first part of the thesis, some of these expectations are examined using semiconductor NWs of different materials. On the basis of the temperature-dependent PL of Au- and selfassisted GaAs/(Al,Ga)As core-shell NWs, the influence of foreign catalyst particles on the optical properties of NWs is investigated. For the Au-assisted NWs, we find a thermally activated, nonradiative recombination channel, possibly related to Auatoms incorporated from the catalyst. These results indicate the limited suitability of catalyst-assisted NWs for optoelectronic applications. The effect of the substrate choice is studied by comparing the PL of ZnO NWs grown on Si, Al{sub 2}O{sub 3}, and ZnO substrates. Their virtually identical optical characteristics indicate that the synthesis of NWs may indeed overcome the constraints that limit the heteroepitaxial deposition of thin films. The major part of this thesis discusses the optical properties of GaN NWs grown on Si substrates. The investigation of the PL of single GaN NWs and GaN NW ensembles reveals the significance of their large surface-to-volume ratio. Differences in the recombination behavior of GaNNW ensembles and GaN layers are observed. First, the large surface-to-volume ratio is discussed to be responsible for the different recombination mechanisms apparent in NWs. Second, certain optical features are only found in the PL of GaN NWs, but not in that of GaN layers. An unexpected broadening of the donor

  13. Is There a Better Semiconductor Firm in Taiwan?

    Directory of Open Access Journals (Sweden)

    Cheng-Wen LEE

    2017-06-01

    Full Text Available The authors investigate the firm value of semiconductor industry in Taiwan in order to differentiate between outstanding semiconductor company and weak semiconductor company. The authors use GAP which is analytical tool to perform four steps: the original maps, sorting maps with clustering trees, summary sufficient maps, and sediment maps. The findings offer a good instruction for policymakers to make related policies in semiconductor firms. Additionally, the paper helps to find firms needed to be reformed through classification by GAP.

  14. Injection of spin-polarized current into semiconductor

    International Nuclear Information System (INIS)

    Vedyayev, A.V.; Dieny, B.; Ryzhanova, N.V.; Zhukov, I.V.; Zhuravlev, M.Ye.; Lutz, H.O.

    2003-01-01

    A quantum-statistical theory of injection of spin-polarized current into a semiconductor in ferromagnet/tunnel barrier/semiconductor system is presented. The presence of Schottky barrier in the semiconductor is taken into account. The case of degenerated and non-degenerated semiconductors are considered. Both the diffusive and ballistic transport regime are investigated. The dependence of current polarization on barrier thickness and temperature is calculated

  15. Self-sustained magnetic islands

    Energy Technology Data Exchange (ETDEWEB)

    Chatenet, J H; Luciani, J F [Ecole Polytechnique, 91 - Palaiseau (France); Garbet, X [Association Euratom-CEA, Centre d` Etudes de Cadarache, 13 - Saint-Paul-lez-Durance (France). Dept. de Recherches sur la Fusion Controlee

    1996-06-01

    Numerical simulations of a single magnetic island evolution are presented in the regime where the island width is smaller than an ion Larmor radius. It is shown that the island rotation is controlled by particle diffusion due to collisions or a background of microturbulence. As expected from the theory of a stationary island, there exist cases where linearly stable magnetic perturbation are nonlinearly self-sustained. This situation corresponds to large poloidal beta and temperature gradient. The drive is due to diamagnetic frequency effects. However, this situation is not generic, and islands can also decay. It is found that a magnetic island is self-sustained for a negative off-diagonal diffusion coefficient. This case occurs in a tokamak if the inward particle pinch is due to the temperature gradient. (author). 30 refs.

  16. Self-sustained magnetic islands

    International Nuclear Information System (INIS)

    Chatenet, J.H.; Luciani, J.F.; Garbet, X.

    1996-06-01

    Numerical simulations of a single magnetic island evolution are presented in the regime where the island width is smaller than an ion Larmor radius. It is shown that the island rotation is controlled by particle diffusion due to collisions or a background of microturbulence. As expected from the theory of a stationary island, there exist cases where linearly stable magnetic perturbation are nonlinearly self-sustained. This situation corresponds to large poloidal beta and temperature gradient. The drive is due to diamagnetic frequency effects. However, this situation is not generic, and islands can also decay. It is found that a magnetic island is self-sustained for a negative off-diagonal diffusion coefficient. This case occurs in a tokamak if the inward particle pinch is due to the temperature gradient. (author)

  17. Semiconductors: A 21st Century Social Studies Topic.

    Science.gov (United States)

    Sunal, Cynthia

    2000-01-01

    Addresses the reasons for exploring semiconductor technology and organic semiconductors in schools for either middle school or secondary students in an interdisciplinary social studies and science environment. Provides background information on transistors and semiconductors. Offers three social studies lessons and related science lessons if an…

  18. 46 CFR 183.360 - Semiconductor rectifier systems.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 7 2010-10-01 2010-10-01 false Semiconductor rectifier systems. 183.360 Section 183.360... TONS) ELECTRICAL INSTALLATION Power Sources and Distribution Systems § 183.360 Semiconductor rectifier systems. (a) Each semiconductor rectifier system must have an adequate heat removal system that prevents...

  19. 46 CFR 129.360 - Semiconductor-rectifier systems.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 4 2010-10-01 2010-10-01 false Semiconductor-rectifier systems. 129.360 Section 129.360... INSTALLATIONS Power Sources and Distribution Systems § 129.360 Semiconductor-rectifier systems. (a) Each semiconductor-rectifier system must have an adequate heat-removal system to prevent overheating. (b) If a...

  20. 46 CFR 120.360 - Semiconductor rectifier systems.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 4 2010-10-01 2010-10-01 false Semiconductor rectifier systems. 120.360 Section 120.360... INSTALLATION Power Sources and Distribution Systems § 120.360 Semiconductor rectifier systems. (a) Each semiconductor rectifier system must have an adequate heat removal system that prevents overheating. (b) Where a...