WorldWideScience

Sample records for semiconductor devices quantum

  1. The Quantum Hydrodynamic Model for Semiconductor Devices: Theory and Computations

    National Research Council Canada - National Science Library

    Gardner, Carl

    1998-01-01

    .... This "smooth" quantum hydrodynamic (QHD) model is derived specifically to handle in a mathematically rigorous way the discontinuities in the classical potential energy which occur at heterojunction barriers in quantum semiconductor devices...

  2. Physical models of semiconductor quantum devices

    CERN Document Server

    Fu, Ying

    2013-01-01

    The science and technology relating to nanostructures continues to receive significant attention for its applications to various fields including microelectronics, nanophotonics, and biotechnology. This book describes the basic quantum mechanical principles underlining this fast developing field. From the fundamental principles of quantum mechanics to nanomaterial properties, from device physics to research and development of new systems, this title is aimed at undergraduates, graduates, postgraduates, and researchers.

  3. Quantum confined laser devices optical gain and recombination in semiconductors

    CERN Document Server

    Blood, Peter

    2015-01-01

    The semiconductor laser, invented over 50 years ago, has had an enormous impact on the digital technologies that now dominate so many applications in business, commerce and the home. The laser is used in all types of optical fibre communication networks that enable the operation of the internet, e-mail, voice and skype transmission. Approximately one billion are produced each year for a market valued at around $5 billion. Nearly all semiconductor lasers now use extremely thin layers of light emitting materials (quantum well lasers). Increasingly smaller nanostructures are used in the form of quantum dots. The impact of the semiconductor laser is surprising in the light of the complexity of the physical processes that determine the operation of every device. This text takes the reader from the fundamental optical gain and carrier recombination processes in quantum wells and quantum dots, through descriptions of common device structures to an understanding of their operating characteristics. It has a consistent...

  4. A quantum energy transport model for semiconductor device simulation

    Energy Technology Data Exchange (ETDEWEB)

    Sho, Shohiro, E-mail: shoshohiro@gmail.com [Graduate School of Information Science and Technology, Osaka University, Osaka (Japan); Odanaka, Shinji [Computer Assisted Science Division, Cybermedia Center, Osaka University, Osaka (Japan)

    2013-02-15

    This paper describes numerical methods for a quantum energy transport (QET) model in semiconductors, which is derived by using a diffusion scaling in the quantum hydrodynamic (QHD) model. We newly drive a four-moments QET model similar with a classical ET model. Space discretization is performed by a new set of unknown variables. Numerical stability and convergence are obtained by developing numerical schemes and an iterative solution method with a relaxation method. Numerical simulations of electron transport in a scaled MOSFET device are discussed. The QET model allows simulations of quantum confinement transport, and nonlocal and hot-carrier effects in scaled MOSFETs.

  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. Heterostructures and quantum devices

    CERN Document Server

    Einspruch, Norman G

    1994-01-01

    Heterostructure and quantum-mechanical devices promise significant improvement in the performance of electronic and optoelectronic integrated circuits (ICs). Though these devices are the subject of a vigorous research effort, the current literature is often either highly technical or narrowly focused. This book presents heterostructure and quantum devices to the nonspecialist, especially electrical engineers working with high-performance semiconductor devices. It focuses on a broad base of technical applications using semiconductor physics theory to develop the next generation of electrical en

  7. Quantum interference measurement of spin interactions in a bio-organic/semiconductor device structure

    Science.gov (United States)

    Deo, Vincent; Zhang, Yao; Soghomonian, Victoria; Heremans, Jean J.

    2015-03-01

    Quantum interference is used to measure the spin interactions between an InAs surface electron system and the iron center in the biomolecule hemin in nanometer proximity in a bio-organic/semiconductor device structure. The interference quantifies the influence of hemin on the spin decoherence properties of the surface electrons. The decoherence times of the electrons serve to characterize the biomolecule, in an electronic complement to the use of spin decoherence times in magnetic resonance. Hemin, prototypical for the heme group in hemoglobin, is used to demonstrate the method, as a representative biomolecule where the spin state of a metal ion affects biological functions. The electronic determination of spin decoherence properties relies on the quantum correction of antilocalization, a result of quantum interference in the electron system. Spin-flip scattering is found to increase with temperature due to hemin, signifying a spin exchange between the iron center and the electrons, thus implying interactions between a biomolecule and a solid-state system in the hemin/InAs hybrid structure. The results also indicate the feasibility of artificial bioinspired materials using tunable carrier systems to mediate interactions between biological entities.

  8. Quantum transport through complex networks - from light-harvesting proteins to semiconductor devices

    Energy Technology Data Exchange (ETDEWEB)

    Kreisbeck, Christoph

    2012-06-18

    Electron transport through small systems in semiconductor devices plays an essential role for many applications in micro-electronics. One focus of current research lies on establishing conceptually new devices based on ballistic transport in high mobility AlGaAs/AlGa samples. In the ballistic regime, the transport characteristics are determined by coherent interference effects. In order to guide experimentalists to an improved device design, the characterization and understanding of intrinsic device properties is crucial. We develop a time-dependent approach that allows us to simulate experimentally fabricated, complex devicegeometries with an extension of up to a few micrometers. Particularly, we explore the physical origin of unexpected effects that have been detected in recent experiments on transport through Aharonov-Bohm waveguide-interferometers. Such interferometers can be configured as detectors for transfer properties of embedded quantum systems. We demonstrate that a four-terminal waveguide-ring is a suitable setup for measuring the transmission phase of a harmonic quantum dot. Quantum effects are not restricted exclusively to artificial devices but have been found in biological systems as well. Pioneering experiments reveal quantum effects in light-harvesting complexes, the building blocks of photosynthesis. We discuss the Fenna-Matthews-Olson complex, which is a network of coupled bacteriochlorophylls. It acts as an energy wire in the photosynthetic apparatus of green sulfur bacteria. Recent experimental findings suggest that energy transfer takes place in the form of coherent wave-like motion, rather than through classical hopping from one bacteriochlorophyll to the next. However, the question of why and how coherent transfer emerges in light-harvesting complexes is still open. The challenge is to merge seemingly contradictory features that are observed in experiments on two-dimensional spectroscopy into a consistent theory. Here, we provide such a

  9. 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.

  10. 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...

  11. Modeling direct band-to-band tunneling: From bulk to quantum-confined semiconductor devices

    Science.gov (United States)

    Carrillo-Nuñez, H.; Ziegler, A.; Luisier, M.; Schenk, A.

    2015-06-01

    A rigorous framework to study direct band-to-band tunneling (BTBT) in homo- and hetero-junction semiconductor nanodevices is introduced. An interaction Hamiltonian coupling conduction and valence bands (CVBs) is derived using a multiband envelope method. A general form of the BTBT probability is then obtained from the linear response to the "CVBs interaction" that drives the system out of equilibrium. Simple expressions in terms of the one-electron spectral function are developed to compute the BTBT current in two- and three-dimensional semiconductor structures. Additionally, a two-band envelope equation based on the Flietner model of imaginary dispersion is proposed for the same purpose. In order to characterize their accuracy and differences, both approaches are compared with full-band, atomistic quantum transport simulations of Ge, InAs, and InAs-Si Esaki diodes. As another numerical application, the BTBT current in InAs-Si nanowire tunnel field-effect transistors is computed. It is found that both approaches agree with high accuracy. The first one is considerably easier to conceive and could be implemented straightforwardly in existing quantum transport tools based on the effective mass approximation to account for BTBT in nanodevices.

  12. 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

  13. 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...

  14. Epitaxial semiconductor quantum wires.

    Science.gov (United States)

    Wu, J; Chen, Y H; Wang, Z G

    2008-07-01

    The investigation on the direct epitaxial quantum wires (QWR) using MBE or MOCVD has been persuited for more than two decades, more lengthy in history as compared with its quantum dot counterpart. Up to now, QWRs with various structural configurations have been produced with different growth methods. This is a reviewing article consisting mainly of two parts. The first part discusses QWRs of various configurations, together with laser devices based on them, in terms of the two growth mechanisms, self-ordering and self-assembling. The second part gives a brief review of the electrical and optical properties of QWRs.

  15. 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

  16. Semiconductor nanocrystals or quantum dots

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 18; Issue 8. Various Quantum Mechanical Concepts for Confinements in Semiconductor Nanocrystals. Jayakrishna Khatei Karuna Kar Nanda. Classroom Volume 18 Issue 8 August 2013 pp 771-776 ...

  17. Superconducting detectors for semiconductor quantum photonics

    International Nuclear Information System (INIS)

    Reithmaier, Guenther M.

    2015-01-01

    In this thesis we present the first successful on-chip detection of quantum light, thereby demonstrating the monolithic integration of superconducting single photon detectors with individually addressable semiconductor quantum dots in a prototypical quantum photonic circuit. Therefore, we optimized both the deposition of high quality superconducting NbN thin films on GaAs substrates and the fabrication of superconducting detectors and successfully integrated these novel devices with GaAs/AlGaAs ridge waveguides loaded with self-assembled InGaAs quantum dots.

  18. Semiconductor-based, large-area, flexible, electronic devices

    Science.gov (United States)

    Goyal, Amit [Knoxville, TN

    2011-03-15

    Novel articles and methods to fabricate the same resulting in flexible, large-area, triaxially textured, single-crystal or single-crystal-like, semiconductor-based, electronic devices are disclosed. Potential applications of resulting articles are in areas of photovoltaic devices, flat-panel displays, thermophotovoltaic devices, ferroelectric devices, light emitting diode devices, computer hard disc drive devices, magnetoresistance based devices, photoluminescence based devices, non-volatile memory devices, dielectric devices, thermoelectric devices and quantum dot laser devices.

  19. Conductance enhancement in quantum-point-contact semiconductor-superconductor devices

    DEFF Research Database (Denmark)

    Mortensen, Asger; Jauho, Antti-Pekka; Flensberg, Karsten

    1999-01-01

    We present numerical calculations of the conductance of an interface between a phase-coherent two-dimensional electron gas and a superconductor with a quantum point contact in the normal region. Using a scattering matrix approach we reconsider the geometry of De Raedt, Michielsen, and Klapwijk...... [Phys. Rev. B 50, 631 (1994)] which was studied within the time-dependent Bogoliubov-de Gennes formalism. We find that the factor-of-2 enhancement of the conductance G(NS) compared to the normal state conductance GN for ideal interfaces may be suppressed for interfaces with a quantum point contact...

  20. Semiconductors and semimetals intersubband transitions in quantum wells physics and device applications

    CERN Document Server

    Weber, Eicke R; Liu, H C

    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 producing 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. Pro

  1. Electrostatic Doping in Semiconductor Devices

    NARCIS (Netherlands)

    Gupta, Gaurav; Rajasekharan, Bijoy; Hueting, Raymond J.E.

    2017-01-01

    To overcome the limitations of chemical doping in nanometer-scale semiconductor devices, electrostatic doping (ED) is emerging as a broadly investigated alternative to provide regions with a high electron or hole density in a semiconductor device. In this paper, we review various reported ED

  2. Semiconductor device physics and simulation

    CERN Document Server

    Yuan, J S

    1998-01-01

    This volume provides thorough coverage of modern semiconductor devices -including hetero- and homo-junction devices-using a two-dimensional simulator (MEDICI) to perform the analysis and generate simulation results Each device is examined in terms of dc, ac, and transient simulator results; relevant device physics; and implications for design and analysis Two hundred forty-four useful figures illustrate the physical mechanisms and characteristics of the devices simulated Comprehensive and carefully organized, Semiconductor Device Physics and Simulation is the ideal bridge from device physics to practical device design

  3. Simulation of semiconductor devices

    CERN Document Server

    Oriato, D

    2001-01-01

    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. In chapter 6 an extensive simulation of the dependence of the optical band gap of a single InGaN quantum well on the piezoelectric and spontaneous polarization is reported. Quantum Confined Stark Effect and screening mechanisms are found to play a major role. The simulation of a novel InGaN/GaN double quantum well LED is presented. A wide well is used to capture electrons that tunnels in a narrow well where they recombine with holes. Resonant asymmetric tunneling of electron and holes is used to increase the efficie...

  4. Transport Imaging for the Study of Quantum Scattering Phenomena in Next Generation Semiconductor Devices

    National Research Council Canada - National Science Library

    Bradley, Frank M

    2005-01-01

    ...) and highly efficient solar cells. A novel technique has been developed utilizing direct imaging of electron/hole recombination via an optical microscope and a high sensitivity charge coupled device coupled to a scanning electron...

  5. Quantum correlations in semiconductor microcavities

    Science.gov (United States)

    Kira, M.; Hoyer, W.; Koch, S. W.; Brick, P.; Ell, C.; Hübner, M.; Khitrova, G.; Gibbs, H. M.

    2003-10-01

    The quantum mechanical nature of the light field in semiconductor microcavities leads to non-classical coupling effects between photons and electron-hole excitations. It is shown that these quantum correlations give rise to characteristic corrections of the semiclassical light-matter coupling dynamics. Examples of quantum correlation signatures include entanglement effects in the probe reflection of a microcavity system and squeezing in the incoherent emission.

  6. Fundamental Quantum 1/f Noise in Ultrasmall Semiconductor Devices and Their Optimal Design Principles.

    Science.gov (United States)

    1985-12-01

    forms of low frequency current noise observed in diodes and other junction devices. As forms which are not of i/f type we mention here: 1) Shot noise...the surface, and the additional electric field arising from the potential jumo 2U at the interface between the bulX and the oxide and passivation...Poissonian) shot noise to be present. ’What Kind of fluctuations are these? This auestion was answered in a orevious oaoer 27 . The additional

  7. Quantum Dot Devices for Optical Signal Processing

    DEFF Research Database (Denmark)

    Chen, Yaohui

    This thesis describes the physics and applications of quantum dot semiconductor optical ampliers through numerical simulations. As nano-structured materials with zero-dimensional quantum connement, semiconductor quantum dot material provides a number of unique physical properties compared...... with other semiconductor materials. The understanding of such properties is important in order to improve the performance of existing devices and to trigger the development of new semiconductor devices for dierent optical signal processing functionalities in the future. We present a detailed quantum dot...... semiconductor optical amplier model incorporating a carrier dynamics rate equation model for quantum dots with inhomogeneous broadening as well as equations describing propagation. A phenomenological description has been used to model the intradot electron scattering between discrete quantum dot states...

  8. Rhombohedrel Hybrid Crystal Semiconductor Device

    Data.gov (United States)

    National Aeronautics and Space Administration — Development of a new high speed and high efficiency hybrid crystal structure semiconductor device based on the the recent invention of rhombohedral hybrid crystal...

  9. 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

  10. Survey of cryogenic semiconductor devices

    Energy Technology Data Exchange (ETDEWEB)

    Talarico, L.J.; McKeever, J.W.

    1996-04-01

    Improved reliability and electronic performance can be achieved in a system operated at cryogenic temperatures because of the reduction in mechanical insult and in disruptive effects of thermal energy on electronic devices. Continuing discoveries of new superconductors with ever increasing values of T{sub c} above that of liquid nitrogen temperature (LNT) have provided incentive for developing semiconductor electronic systems that may also operate in the superconductor`s liquid nitrogen bath. Because of the interest in high-temperature superconductor (HTS) devices, liquid nitrogen is the cryogen of choice and LNT is the temperature on which this review is focused. The purpose of this survey is to locate and assemble published information comparing the room temperature (298 K), performance of commercially available conventional and hybrid semiconductor device with their performance at LNT (77K), to help establish their candidacy as cryogenic electronic devices specifically for use at LNT. The approach to gathering information for this survey included the following activities. Periodicals and proceedings were searched for information on the behavior of semiconductor devices at LNT. Telephone calls were made to representatives of semiconductor industries, to semiconductor subcontractors, to university faculty members prominent for their research in the area of cryogenic semiconductors, and to representatives of the National Aeronautics and Space Administration (NASA) and NASA subcontractors. The sources and contacts are listed with their responses in the introduction, and a list of references appears at the end of the survey.

  11. Quantum Optical Effects in Semiconductors

    Science.gov (United States)

    Hoyer, W.; Kira, M.; Koch, S. W.

    Quantum optical effects in semiconductors are studied using a density-matrix approach which takes into account the many-body Coulomb interaction among the charge carriers, coupling to lattice vibrations, and the quantum nature of light. The theory provides a consistent set of equations which is used to compute photoluminescence spectra, predict the emission of squeezed light, investigate correlations between photons emitted by quantum-well structures, and to show examples where light-matter entanglement influences experiments done with classical optical fields.

  12. 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

  13. Quantum Confined Semiconductors

    Science.gov (United States)

    2015-02-01

    RCR    , (5) which considers all elastic scattering events on the energy shell kk EEE   , which is appropriate for all scattering...fluctuations in semiconductor superlattices using a magneto -transport technique,” Superlattices and Microstructures 15, 225-228 (1994). 12. I. Dharssi and...εyy is consistently slightly tensile (≈ -1%), which agreed with theoretical calculations of εyy based on published values of elastic constants. An

  14. Overview of antimonide based III-V semiconductor epitaxial layers and their applications at the center for quantum devices

    Science.gov (United States)

    Razeghi, M.

    2003-09-01

    The properties of Sb-based III-V semiconductor compounds for optoelectronic applications in the mid-wavelength infrared (MWIR) and long-wavelength infrared (LWIR) range were reviewed. The growths of the Sb-based binary, ternary and quaternary were studied by molecular beam epitaxy (MBE) and metalorganic chemical vapor deposition (MOCVD). The structural, optical and electrical characterizations were carried out. Focal plane array, photoconductors and photodiodes were fabricated for the MWIR and LWIR range. Doublehetero structure (DH), multi-quantum well (MQW) and strained superlattice (SSL) lasers in the 3 5 μm range were fabricated. InAs-GaSb type-II superlattices were designed, grown and fabricated into photodetectors for the MWIR and LWIR range.

  15. 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.)

  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. 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...

  18. Electronic states of semiconductor-metal-semiconductor quantum-well structures

    Science.gov (United States)

    Huberman, M. L.; Maserjian, J.

    1988-01-01

    Quantum-size effects are calculated in thin layered semiconductor-metal-semiconductor structures using an ideal free-electron model for the metal layer. The results suggest new quantum-well structures having device applications. Structures with sufficiently high-quality interfaces should exhibit effects such as negative differential resistance due to tunneling between allowed states. Similarly, optical detection by intersubband absorption may be possible. Ultrathin metal layers are predicted to behave as high-density dopant sheets.

  19. GaAs metal-oxide-semiconductor based non-volatile flash memory devices with InAs quantum dots as charge storage nodes

    International Nuclear Information System (INIS)

    Islam, Sk Masiul; Chowdhury, Sisir; Sarkar, Krishnendu; Nagabhushan, B.; Banerji, P.; Chakraborty, S.; Mukherjee, Rabibrata

    2015-01-01

    Ultra-thin InP passivated GaAs metal-oxide-semiconductor based non-volatile flash memory devices were fabricated using InAs quantum dots (QDs) as charge storing elements by metal organic chemical vapor deposition technique to study the efficacy of the QDs as charge storage elements. The grown QDs were embedded between two high-k dielectric such as HfO 2 and ZrO 2 , which were used for tunneling and control oxide layers, respectively. The size and density of the QDs were found to be 5 nm and 1.8×10 11 cm −2 , respectively. The device with a structure Metal/ZrO 2 /InAs QDs/HfO 2 /GaAs/Metal shows maximum memory window equivalent to 6.87 V. The device also exhibits low leakage current density of the order of 10 −6 A/cm 2 and reasonably good charge retention characteristics. The low value of leakage current in the fabricated memory device is attributed to the Coulomb blockade effect influenced by quantum confinement as well as reduction of interface trap states by ultra-thin InP passivation on GaAs prior to HfO 2 deposition

  20. Voltage-controlled quantum light from an atomically thin semiconductor

    Science.gov (United States)

    Chakraborty, Chitraleema; Kinnischtzke, Laura; Goodfellow, Kenneth M.; Beams, Ryan; Vamivakas, A. Nick

    2015-06-01

    Although semiconductor defects can often be detrimental to device performance, they are also responsible for the breadth of functionality exhibited by modern optoelectronic devices. Artificially engineered defects (so-called quantum dots) or naturally occurring defects in solids are currently being investigated for applications ranging from quantum information science and optoelectronics to high-resolution metrology. In parallel, the quantum confinement exhibited by atomically thin materials (semi-metals, semiconductors and insulators) has ushered in an era of flatland optoelectronics whose full potential is still being articulated. In this Letter we demonstrate the possibility of leveraging the atomically thin semiconductor tungsten diselenide (WSe2) as a host for quantum dot-like defects. We report that this previously unexplored solid-state quantum emitter in WSe2 generates single photons with emission properties that can be controlled via the application of external d.c. electric and magnetic fields. These new optically active quantum dots exhibit excited-state lifetimes on the order of 1 ns and remarkably large excitonic g-factors of 10. It is anticipated that WSe2 quantum dots will provide a novel platform for integrated solid-state quantum photonics and quantum information processing, as well as a rich condensed-matter physics playground with which to explore the coupling of quantum dots and atomically thin semiconductors.

  1. Introductory quantum mechanics for semiconductor nanotechnology

    International Nuclear Information System (INIS)

    Kim, Dae Mann

    2010-01-01

    The result of the nano education project run by the Korean Nano Technology Initiative, this has been recommended for use as official textbook by the Korean Nanotechnology Research Society. The author is highly experienced in teaching both physics and engineering in academia and industry, and naturally adopts an interdisciplinary approach here. He is short on formulations but long on applications, allowing students to understand the essential workings of quantum mechanics without spending too much time covering the wide realms of physics. He takes care to provide sufficient technical background and motivation for students to pursue further studies of advanced quantum mechanics and stresses the importance of translating quantum insights into useful and tangible innovations and inventions. As such, this is the only work to cover semiconductor nanotechnology from the perspective of introductory quantum mechanics, with applications including mainstream semiconductor technologies as well as (nano)devices, ranging from photodetectors, laser diodes, and solar cells to transistors and Schottky contacts. Problems are also provided to test the reader's understanding and supplementary material available includes working presentation files, solutions and instructors manuals. (orig.)

  2. Quantum Confined Semiconductors for High Efficiency Photovoltaics

    Science.gov (United States)

    Beard, Matthew

    2014-03-01

    Semiconductor nanostructures, where at least one dimension is small enough to produce quantum confinement effects, provide new pathways for controlling energy flow and therefore have the potential to increase the efficiency of the primary photon-to-free energy conversion step. In this discussion, I will present the current status of research efforts towards utilizing the unique properties of colloidal quantum dots (NCs confined in three dimensions) in prototype solar cells and demonstrate that these unique systems have the potential to bypass the Shockley-Queisser single-junction limit for solar photon conversion. The solar cells are constructed using a low temperature solution based deposition of PbS or PbSe QDs as the absorber layer. Different chemical treatments of the QD layer are employed in order to obtain good electrical communication while maintaining the quantum-confined properties of the QDs. We have characterized the transport and carrier dynamics using a transient absorption, time-resolved THz, and temperature-dependent photoluminescence. I will discuss the interplay between carrier generation, recombination, and mobility within the QD layers. A unique aspect of our devices is that the QDs exhibit multiple exciton generation with an efficiency that is ~ 2 to 3 times greater than the parental bulk semiconductor.

  3. Semiconductor quantum optics with tailored photonic nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Laucht, Arne

    2011-06-15

    This thesis describes detailed investigations of the effects of photonic nanostructures on the light emission properties of self-assembled InGaAs quantum dots. Nanoscale optical cavities and waveguides are employed to enhance the interaction between light and matter, i.e. photons and excitons, up to the point where optical non-linearities appear at the quantum (single photon) level. Such non-linearities are an essential component for the realization of hardware for photon based quantum computing since they can be used for the creation and detection of non-classical states of light and may open the way to new genres of quantum optoelectronic devices such as optical modulators and optical transistors. For single semiconductor quantum dots in photonic crystal nanocavities we investigate the coupling between excitonic transitions and the highly localized mode of the optical cavity. We explore the non-resonant coupling mechanisms which allow excitons to couple to the cavity mode, even when they are not spectrally in resonance. This effect is not observed for atomic cavity quantum electrodynamics experiments and its origin is traced to phonon-assisted scattering for small detunings ({delta}E<{proportional_to}5 meV) and a multi-exciton-based, Auger-like process for larger detunings ({delta}E >{proportional_to}5 meV). For quantum dots in high-Q cavities we observe the coherent coupling between exciton and cavity mode in the strong coupling regime of light-matter interaction, probe the influence of pure dephasing on the coherent interaction at high excitation levels and high lattice temperatures, and examine the coupling of two spatially separated quantum dots via the exchange of real and virtual photons mediated by the cavity mode. Furthermore, we study the spontaneous emission properties of quantum dots in photonic crystal waveguide structures, estimate the fraction of all photons emitted into the propagating waveguide mode, and demonstrate the on-chip generation of

  4. Semiconductor quantum optics with tailored photonic nanostructures

    International Nuclear Information System (INIS)

    Laucht, Arne

    2011-01-01

    This thesis describes detailed investigations of the effects of photonic nanostructures on the light emission properties of self-assembled InGaAs quantum dots. Nanoscale optical cavities and waveguides are employed to enhance the interaction between light and matter, i.e. photons and excitons, up to the point where optical non-linearities appear at the quantum (single photon) level. Such non-linearities are an essential component for the realization of hardware for photon based quantum computing since they can be used for the creation and detection of non-classical states of light and may open the way to new genres of quantum optoelectronic devices such as optical modulators and optical transistors. For single semiconductor quantum dots in photonic crystal nanocavities we investigate the coupling between excitonic transitions and the highly localized mode of the optical cavity. We explore the non-resonant coupling mechanisms which allow excitons to couple to the cavity mode, even when they are not spectrally in resonance. This effect is not observed for atomic cavity quantum electrodynamics experiments and its origin is traced to phonon-assisted scattering for small detunings (ΔE ∝5 meV). For quantum dots in high-Q cavities we observe the coherent coupling between exciton and cavity mode in the strong coupling regime of light-matter interaction, probe the influence of pure dephasing on the coherent interaction at high excitation levels and high lattice temperatures, and examine the coupling of two spatially separated quantum dots via the exchange of real and virtual photons mediated by the cavity mode. Furthermore, we study the spontaneous emission properties of quantum dots in photonic crystal waveguide structures, estimate the fraction of all photons emitted into the propagating waveguide mode, and demonstrate the on-chip generation of single photon emission into the waveguide. The results obtained during the course of this thesis contribute significantly to

  5. Method for fabricating semiconductor devices

    Science.gov (United States)

    Kaiser, William J. (Inventor); Grunthaner, Frank J. (Inventor); Hecht, Michael H. (Inventor); Bell, Lloyd D. (Inventor)

    1995-01-01

    A process for fabricating gold/gallium arsenide structures, in situ, on molecular beam epitaxially grown gallium arsenide. The resulting interface proves to be Ohmic, an unexpected result which is interpreted in terms of increased electrode interdiffusion. More importantly, the present invention surprisingly permits the fabrication of Ohmic contacts in a III-V semiconductor material at room temperature. Although it may be desireable to heat the Ohmic contact to a temperature of, for example, 200 degrees Centigrade if one wishes to further decrease the resistance of the contact, such low temperature annealing is much less likely to have any deleterious affect on the underlying substrate. The use of the term in situ herein, contemplates continuously maintaining an ultra-high vacuum, that is a vacuum which is at least 10.sup.-8 Torr, until after the metallization has been completed. An alternative embodiment of the present invention comprising an additional step, namely the termination of the gallium arsenide by a two monolayer thickness of epitaxial aluminum arsenide as a diffusion barrier, enables the recovery of Schottky barrier behavior, namely a rectified I-V characteristic. The present invention provides a significant breakthrough in the fabrication of III-V semiconductor devices wherein excellent Ohmic contact and Schottky barrier interfaces to such devices can be achieved simply and inexpensively and without requiring the high temperature processing of the prior art and also without requiring the use of exotic high temperature refractory materials as substitutes for those preferred contact metals such as gold, aluminum and the like.

  6. Semiconductor quantum dot amplifiers for optical signal processing

    DEFF Research Database (Denmark)

    Berg, Tommy Winther; Uskov, A. V.; Bischoff, Svend

    2001-01-01

    The dynamics of quantum dot semiconductor amplifiers are investigated theoretically with respect to the potential for ultrafast signal processing. The high-speed signal processing capacity of these devices is found to be limited by the wetting layer dynamics in case of electrical pumping, while...... optical pumping partly removes this limitation. Also, the possibility of using spectral hole burning for signal processing is discussed....

  7. Gain dynamics and saturation in semiconductor quantum dot amplifiers

    DEFF Research Database (Denmark)

    Berg, Tommy Winther; Mørk, Jesper; Hvam, Jørn Märcher

    2004-01-01

    Quantum dot (QD)-based semiconductor optical amplifiers offer unique properties compared with conventional devices based on bulk or quantum well material. Due to the bandfilling properties of QDs and the existence of a nearby reservoir of carriers in the form of a wetting layer, QD semiconductor...... optical amplifiers may be operated in regimes of high linearity, i.e. with a high saturation power, but can also show strong and fast nonlinearities by breaking the equilibrium between discrete dot states and the continuum of wetting layer states. In this paper, we analyse the interplay of these two...

  8. Semiconductor power devices physics, characteristics, reliability

    CERN Document Server

    Lutz, Josef; Scheuermann, Uwe; De Doncker, Rik

    2011-01-01

    Semiconductor power devices are the heart of power electronics. They determine the performance of power converters and allow topologies with high efficiency. Semiconductor properties, pn-junctions and the physical phenomena for understanding power devices are discussed in depth. Working principles of state-of-the-art power diodes, thyristors, MOSFETs and IGBTs are explained in detail, as well as key aspects of semiconductor device production technology. In practice, not only the semiconductor, but also the thermal and mechanical properties of packaging and interconnection technologies are esse

  9. Semiconductor-based, large-area, flexible, electronic devices on {110} oriented substrates

    Science.gov (United States)

    Goyal, Amit

    2014-08-05

    Novel articles and methods to fabricate the same resulting in flexible, oriented, semiconductor-based, electronic devices on {110} textured substrates are disclosed. Potential applications of resulting articles are in areas of photovoltaic devices, flat-panel displays, thermophotovoltaic devices, ferroelectric devices, light emitting diode devices, computer hard disc drive devices, magnetoresistance based devices, photoluminescence based devices, non-volatile memory devices, dielectric devices, thermoelectric devices and quantum dot laser devices.

  10. [100] or [110] aligned, semiconductor-based, large-area, flexible, electronic devices

    Science.gov (United States)

    Goyal, Amit

    2015-03-24

    Novel articles and methods to fabricate the same resulting in flexible, large-area, [100] or [110] textured, semiconductor-based, electronic devices are disclosed. Potential applications of resulting articles are in areas of photovoltaic devices, flat-panel displays, thermophotovoltaic devices, ferroelectric devices, light emitting diode devices, computer hard disc drive devices, magnetoresistance based devices, photoluminescence based devices, non-volatile memory devices, dielectric devices, thermoelectric devices and quantum dot laser devices.

  11. {100} or 45.degree.-rotated {100}, semiconductor-based, large-area, flexible, electronic devices

    Science.gov (United States)

    Goyal, Amit [Knoxville, TN

    2012-05-15

    Novel articles and methods to fabricate the same resulting in flexible, {100} or 45.degree.-rotated {100} oriented, semiconductor-based, electronic devices are disclosed. Potential applications of resulting articles are in areas of photovoltaic devices, flat-panel displays, thermophotovoltaic devices, ferroelectric devices, light emitting diode devices, computer hard disc drive devices, magnetoresistance based devices, photoluminescence based devices, non-volatile memory devices, dielectric devices, thermoelectric devices and quantum dot laser devices.

  12. Hybrid quantum-classical modeling of quantum dot devices

    Science.gov (United States)

    Kantner, Markus; Mittnenzweig, Markus; Koprucki, Thomas

    2017-11-01

    The design of electrically driven quantum dot devices for quantum optical applications asks for modeling approaches combining classical device physics with quantum mechanics. We connect the well-established fields of semiclassical semiconductor transport theory and the theory of open quantum systems to meet this requirement. By coupling the van Roosbroeck system with a quantum master equation in Lindblad form, we introduce a new hybrid quantum-classical modeling approach, which provides a comprehensive description of quantum dot devices on multiple scales: it enables the calculation of quantum optical figures of merit and the spatially resolved simulation of the current flow in realistic semiconductor device geometries in a unified way. We construct the interface between both theories in such a way, that the resulting hybrid system obeys the fundamental axioms of (non)equilibrium thermodynamics. We show that our approach guarantees the conservation of charge, consistency with the thermodynamic equilibrium and the second law of thermodynamics. The feasibility of the approach is demonstrated by numerical simulations of an electrically driven single-photon source based on a single quantum dot in the stationary and transient operation regime.

  13. Electron Spins in Semiconductor Quantum Dots

    NARCIS (Netherlands)

    Hanson, R.

    2005-01-01

    This thesis describes a series of experiments aimed at understanding and controlling the behavior of the spin degree of freedom of single electrons, confined in semiconductor quantum dots. This research work is motivated by the prospects of using the electron spin as a quantum bit (qubit), the basic

  14. Many electron effects in semiconductor quantum dots

    Indian Academy of Sciences (India)

    Home; Journals; Bulletin of Materials Science; Volume 26; Issue 1. Many electron effects in ... Semiconductor quantum dots (QDs) exhibit shell structures, very similar to atoms. Termed as 'artificial atoms' by some, ... Our calculations have been performed in a three-dimensional quantum dot. We have carried out a study of ...

  15. 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...

  16. Semiconductor radiation detectors device physics

    CERN Document Server

    Lutz, Gerhard

    1999-01-01

    Describes the field of modern semiconductor detectors used for energy and position measurement radiation. This book includes an introduction to semiconductor physics. It explains the principles of semiconductor radiation detectors, followed by formal quantitative analysis. It also covers electronic signal readout.

  17. Quantum theory of the optical and electronic properties of semiconductors

    CERN Document Server

    Haug, Hartmut

    1990-01-01

    The current technological revolution in the development of computing devices has created a demand for a textbook on the quantum theory of the electronic and optical properties of semiconductors and semiconductor devices. This book successfully fulfills this need. Based on lectures given by the authors, it is a comprehensive introduction for researchers or graduate-level students to the subject. Certain sections can also serve as a graduate-level textbook for use in solid state physics courses or for more specialized courses. The final chapters establish a direct link to current research in sem

  18. Quantum Thermal Transport in Semiconductor Nanostructures

    Science.gov (United States)

    Miao, Kai

    Modern semiconductor devices scale down to the nanometer range. Heat dissipation becomes a critical issue in the chip design. From a different perspective, energy conservation has attracted much of attention from researchers. The essence of heat dissipation and energy conservation is the heat transport. Thermal properties of semiconductors have been under intense investigation in recent decades. Classical models fail to consider the quantum effects in devices on the scale of nanometers. First-principle methods only can deal with small devices and is computationally intensive. Instead, a modified valence force field (VFF) model is applied to reproduce the phonon properties of different materials and devices. Phonon transport is explored using the Green's functions. The concept of a Buttiker probe model is first used to mimic the scattering mechanisms in phonon transport. This energy conservation model is straightforward and efficient in describing scattering. In the quasiparticle approximation, phonon scattering will cause a phonon energy shift. This energy shift is represented by the scattering self-energy in a retarded Green's function. Phonon lifetime is extracted from the scattering self-energy expression. Different relaxation time approximation (RTA) models are studied and coupled with the phonon Green's function method for the first time. We prove that the widely used and proven RTA models in the Boltzmann transport equation (BTE) survive in the atomistic Green's function method. This method can give accurate thermal properties agreeing closely with the experimental results for bulk devices. This atomistic method can also consider quantum confinement effects at the nanoscale. The heat transport across a Si/Ge interface is introduced in this work as an example for this application. The heat transfer across metal/semiconductor (MS) interfaces is investigated as well. Relaxation at the interface can be done in two different ways. Using VFF model to relax the

  19. Quantum information processing with electronic and nuclear spins in semiconductors

    Science.gov (United States)

    Klimov, Paul Victor

    Traditional electronic and communication devices operate by processing binary information encoded as bits. Such digital devices have led to the most advanced technologies that we encounter in our everyday lives and they influence virtually every aspect of our society. Nonetheless, there exists a much richer way to encode and process information. By encoding information in quantum mechanical states as qubits, phenomena such as coherence and entanglement can be harnessed to execute tasks that are intractable to digital devices. Under this paradigm, it should be possible to realize quantum computers, quantum communication networks and quantum sensors that outperform their classical counterparts. The electronic spin states of color-center defects in the semiconductor silicon carbide have recently emerged as promising qubit candidates. They have long-lived quantum coherence up to room temperature, they can be controlled with mature magnetic resonance techniques, and they have a built-in optical interface operating near the telecommunication bands. In this thesis I will present two of our contributions to this field. The first is the electric-field control of electron spin qubits. This development lays foundation for quantum electronics that operate via electrical gating, much like traditional electronics. The second is the universal control and entanglement of electron and nuclear spin qubits in an ensemble under ambient conditions. This development lays foundation for quantum devices that have a built-in redundancy and can operate in real-world conditions. Both developments represent important steps towards practical quantum devices in an electronic grade material.

  20. Quantum dot devices for optical communications

    DEFF Research Database (Denmark)

    Mørk, Jesper

    2005-01-01

    -low threshold currents and amplifiers with record-high power levels. In this tutorial we will review the basic properties of quantum dots, emphasizing the properties which are important for laser and amplifier applications, as well as devices for all-optical signal processing. The high-speed properties....... The main property of semiconductor quantum dots compared to bulk material or even quantum well structures is the discrete nature of the allowed states, which means that inversion of the medium can be obtained for very low electron densities. This has led to the fabrication of quantum dot lasers with record...

  1. 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)

  2. Fluctuations in quantum devices

    Directory of Open Access Journals (Sweden)

    H.Haken

    2004-01-01

    Full Text Available Logical gates can be formalized by Boolean algebra whose elementary operations can be realized by devices that employ the interactions of macroscopic numbers of elementary excitations such as electrons, holes, photons etc. With increasing miniaturization to the nano scale and below, quantum fluctuations become important and can no longer be ignored. Based on Heisenberg equations of motion for the creation and annihilation operators of elementary excitations, I determine the noise sources of composite quantum systems.

  3. 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

  4. 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.

  5. Electron Spin Dynamics in Semiconductor Quantum Dots

    International Nuclear Information System (INIS)

    Marie, X.; Belhadj, T.; Urbaszek, B.; Amand, T.; Krebs, O.; Lemaitre, A.; Voisin, P.

    2011-01-01

    An electron spin confined to a semiconductor quantum dot is not subject to the classical spin relaxation mechanisms known for free carriers but it strongly interacts with the nuclear spin system via the hyperfine interaction. We show in time resolved photoluminescence spectroscopy experiments on ensembles of self assembled InAs quantum dots in GaAs that this interaction leads to strong electron spin dephasing.

  6. Biosensing with Luminescent Semiconductor Quantum Dots

    OpenAIRE

    Sapsford, Kim E.; Pons, Thomas; Medintz, Igor L.; Mattoussi, Hedi

    2006-01-01

    Luminescent semiconductor nanocrystals or quantum dots (QDs) are a recently developed class of nanomaterial whose unique photophysical properties are helping to create a new generation of robust fluorescent biosensors. QD properties of interest for biosensing include high quantum yields, broad absorption spectra coupled to narrow size-tunable photoluminescent emissions and exceptional resistance to both photobleaching and chemical degradation. In this review, we examine the progress in adapti...

  7. 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)

  8. Semiconductor radiation detectors. Device physics

    Energy Technology Data Exchange (ETDEWEB)

    Lutz, G. [Max-Planck-Institutes for Physics and Extraterrestrial Physics, Muenchen (Germany). Semiconductor Lab.

    2007-07-01

    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. Band structures of graphene hexagonal lattice semiconductor quantum dots

    Science.gov (United States)

    Peng, Juan; Li, Shu-Shen

    2010-12-01

    Electronic structures of coupled semiconductor quantum dots (QDs) arranged as graphene hexagonal lattice are studied theoretically using the tight-binding method. In our calculations, the electrons can hop to the third-nearest-neighbors, and the overlap matrix as well as the multicenter integral are taken into account. The novel two-dimensional Dirac-like electronic excitations in graphene are found in these artificial planar QD structures. The results provide the theoretical basis for searching Dirac fermions in QD materials and have great significance for investigating and making semiconductor QD devices.

  10. Coprocessors for quantum devices

    Science.gov (United States)

    Kay, Alastair

    2018-03-01

    Quantum devices, from simple fixed-function tools to the ultimate goal of a universal quantum computer, will require high-quality, frequent repetition of a small set of core operations, such as the preparation of entangled states. These tasks are perfectly suited to realization by a coprocessor or supplementary instruction set, as is common practice in modern CPUs. In this paper, we present two quintessentially quantum coprocessor functions: production of a Greenberger-Horne-Zeilinger state and implementation of optimal universal (asymmetric) quantum cloning. Both are based on the evolution of a fixed Hamiltonian. We introduce a technique for deriving the parameters of these Hamiltonians based on the numerical integration of Toda-like flows.

  11. Quantum dot optoelectronic devices: lasers, photodetectors and solar cells

    International Nuclear Information System (INIS)

    Wu, Jiang; Chen, Siming; Seeds, Alwyn; Liu, Huiyun

    2015-01-01

    Nanometre-scale semiconductor devices have been envisioned as next-generation technologies with high integration and functionality. Quantum dots, or the so-called ‘artificial atoms’, exhibit unique properties due to their quantum confinement in all 3D. These unique properties have brought to light the great potential of quantum dots in optoelectronic applications. Numerous efforts worldwide have been devoted to these promising nanomaterials for next-generation optoelectronic devices, such as lasers, photodetectors, amplifiers, and solar cells, with the emphasis on improving performance and functionality. Through the development in optoelectronic devices based on quantum dots over the last two decades, quantum dot devices with exceptional performance surpassing previous devices are evidenced. This review describes recent developments in quantum dot optoelectronic devices over the last few years. The paper will highlight the major progress made in 1.3 μm quantum dot lasers, quantum dot infrared photodetectors, and quantum dot solar cells. (topical review)

  12. A quantum computer based on recombination processes in microelectronic devices

    International Nuclear Information System (INIS)

    Theodoropoulos, K; Ntalaperas, D; Petras, I; Konofaos, N

    2005-01-01

    In this paper a quantum computer based on the recombination processes happening in semiconductor devices is presented. A 'data element' and a 'computational element' are derived based on Schokley-Read-Hall statistics and they can later be used to manifest a simple and known quantum computing process. Such a paradigm is shown by the application of the proposed computer onto a well known physical system involving traps in semiconductor devices

  13. Many electron effects in semiconductor quantum dots

    Indian Academy of Sciences (India)

    Semiconductor quantum dots (QDs) exhibit shell structures, very similar to atoms. Termed as 'artificial atoms' by some, they are much larger (1 100 nm) than real atoms. One can study a variety of manyelectron effects in them, which are otherwise difficult to observe in a real atom. We have treated these effects within the ...

  14. Competing interactions in semiconductor quantum dots

    NARCIS (Netherlands)

    van den Berg, R.; Brandino, G.P.; El Araby, O.; Konik, R.M.; Gritsev, V.; Caux, J.S.

    2014-01-01

    We introduce an integrability-based method enabling the study of semiconductor quantum dot models incorporating both the full hyperfine interaction as well as a mean-field treatment of dipole-dipole interactions in the nuclear spin bath. By performing free-induction decay and spin-echo simulations

  15. Mathematical Modelling and Simulation of Electrical Circuits and Semiconductor Devices

    CERN Document Server

    Merten, K; Bulirsch, R

    1990-01-01

    Numerical simulation and modelling of electric circuits and semiconductor devices are of primal interest in today's high technology industries. At the Oberwolfach Conference more than forty scientists from around the world, in­ cluding applied mathematicians and electrical engineers from industry and universities, presented new results in this area of growing importance. The contributions to this conference are presented in these proceedings. They include contributions on special topics of current interest in circuit and device simulation, as well as contributions that present an overview of the field. In the semiconductor area special lectures were given on mixed finite element methods and iterative procedures for the solution of large linear systems. For three dimensional models new discretization procedures including software packages were presented. Con­ nections between semiconductor equations and the Boltzmann equation were shown as well as relations to the quantum transport equation. Other issues dis...

  16. Semiconductor Quantum Dash Broadband Emitters: Modeling and Experiments

    KAUST Repository

    Khan, Mohammed Zahed Mustafa

    2013-10-01

    Broadband light emitters operation, which covers multiple wavelengths of the electromagnetic spectrum, has been established as an indispensable element to the human kind, continuously advancing the living standard by serving as sources in important multi-disciplinary field applications such as biomedical imaging and sensing, general lighting and internet and mobile phone connectivity. In general, most commercial broadband light sources relies on complex systems for broadband light generation which are bulky, and energy hungry. \\tRecent demonstration of ultra-broadband emission from semiconductor light sources in the form of superluminescent light emitting diodes (SLDs) has paved way in realization of broadband emitters on a completely novel platform, which offered compactness, cost effectiveness, and comparatively energy efficient, and are already serving as a key component in medical imaging systems. The low power-bandwidth product is inherent in SLDs operating in the amplified spontaneous emission regime. A quantum leap in the advancement of broadband emitters, in which high power and large bandwidth (in tens of nm) are in demand. Recently, the birth of a new class of broadband semiconductor laser diode (LDs) producing multiple wavelength light in stimulated emission regime was demonstrated. This very recent manifestation of a high power-bandwidth-product semiconductor broadband LDs relies on interband optical transitions via quantum confined dot/dash nanostructures and exploiting the natural inhomogeneity of the self-assembled growth technology. This concept is highly interesting and extending the broad spectrum of stimulated emission by novel device design forms the central focus of this dissertation. \\tIn this work, a simple rate equation numerical technique for modeling InAs/InP quantum dash laser incorporating the properties of inhomogeneous broadening effect on lasing spectra was developed and discussed, followed by a comprehensive experimental analysis

  17. Niobium Nitride Josephson Devices with Semiconductor Barriers.

    Science.gov (United States)

    1981-09-01

    impedance of the semiconductor side of the device.17 (An exception is the silicon membrane structures of Huang and Van Duzer . 2) In our devices this...and T. Van Duzer , Appl. Phys. Lett. 25, 753 (1974). 3. M. Schyfter, J. Maah-Sango, N. Ralez, R. Rubz, B. T. Alrich, and T. Van Duzer , IEEE Trans

  18. 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...

  19. Optical generation and control of quantum coherence in semiconductor nanostructures

    CERN Document Server

    Slavcheva, Gabriela

    2010-01-01

    The unprecedented control of coherence that can be exercised in quantum optics of atoms and molecules has stimulated increasing efforts in extending it to solid-state systems. One motivation to exploit the coherent phenomena comes from the emergence of the quantum information paradigm, however many more potential device applications ranging from novel lasers to spintronics are all bound up with issues in coherence. The book focuses on recent advances in the optical control of coherence in excitonic and polaritonic systems as model systems for the complex semiconductor dynamics towards the goal

  20. Device for measuring semiconductor radiation sources

    International Nuclear Information System (INIS)

    Schubert, W.; Wendt, H.; Doss, R.

    1975-01-01

    In a measuring device, the determination of the local dependence of the intensity and/or the delay time of the recombination radiation on the radiation band of a semiconductor radiation source is reduced to phase measuring so as to enable short delays at 10 -11 seconds to be determined. The measuring device comprises an excitation source for a semiconductor radiation source, a magnifying optical system which images the semiconductor radiation source on a diaphragm having a radiation receiver in its rear. A phasemeter connected to the excitation receiver on the one hand and to the radiation receiver on the other, compares the phase of the excitation signal to the phase of the received signal. The image of the semiconductor radiation source is displaceable relatively to the diaphragm and can be viewed through an observation system. (auth)

  1. Quantum optics with single quantum dot devices

    International Nuclear Information System (INIS)

    Zwiller, Valery; Aichele, Thomas; Benson, Oliver

    2004-01-01

    A single radiative transition in a single-quantum emitter results in the emission of a single photon. Single quantum dots are single-quantum emitters with all the requirements to generate single photons at visible and near-infrared wavelengths. It is also possible to generate more than single photons with single quantum dots. In this paper we show that single quantum dots can be used to generate non-classical states of light, from single photons to photon triplets. Advanced solid state structures can be fabricated with single quantum dots as their active region. We also show results obtained on devices based on single quantum dots

  2. NATO Advanced Study Institute on Physics of Submicron Semiconductor Devices

    CERN Document Server

    Ferry, David; Jacoboni, C

    1988-01-01

    The papers contained in the volume represent lectures delivered as a 1983 NATO ASI, held at Urbino, Italy. The lecture series was designed to identify the key submicron and ultrasubmicron device physics, transport, materials and contact issues. Nonequilibrium transport, quantum transport, interfacial and size constraints issues were also highlighted. The ASI was supported by NATO and the European Research Office. H. L. Grubin D. K. Ferry C. Jacoboni v CONTENTS MODELLING OF SUB-MICRON DEVICES.................. .......... 1 E. Constant BOLTZMANN TRANSPORT EQUATION... ... ...... .................... 33 K. Hess TRANSPORT AND MATERIAL CONSIDERATIONS FOR SUBMICRON DEVICES. . .. . . . . .. . . . .. . .. . .... ... .. . . . .. . . . .. . . . . . . . . . . 45 H. L. Grubin EPITAXIAL GROWTH FOR SUB MICRON STRUCTURES.................. 179 C. E. C. Wood INSULATOR/SEMICONDUCTOR INTERFACES.......................... 195 C. W. Wilms en THEORY OF THE ELECTRONIC STRUCTURE OF SEMICONDUCTOR SURFACES AND INTERFACES...................

  3. 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...

  4. 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.

  5. Quantum theory of the optical and electronic properties of semiconductors

    CERN Document Server

    Haug, Hartmut

    2009-01-01

    This invaluable textbook presents the basic elements needed to understand and research into semiconductor physics. It deals with elementary excitations in bulk and low-dimensional semiconductors, including quantum wells, quantum wires and quantum dots. The basic principles underlying optical nonlinearities are developed, including excitonic and many-body plasma effects. Fundamentals of optical bistability, semiconductor lasers, femtosecond excitation, the optical Stark effect, the semiconductor photon echo, magneto-optic effects, as well as bulk and quantum-confined Franz-Keldysh effects, are covered. The material is presented in sufficient detail for graduate students and researchers with a general background in quantum mechanics.This fifth edition includes an additional chapter on 'Quantum Optical Effects' where the theory of quantum optical effects in semiconductors is detailed. Besides deriving the 'semiconductor luminescence equations' and the expression for the stationary luminescence spectrum, the resu...

  6. Chaotic electron transport in semiconductor devices

    Science.gov (United States)

    Scannell, William Christian

    The field of quantum chaos investigates the quantum mechanical behavior of classically chaotic systems. This dissertation begins by describing an experiment conducted on an apparatus constructed to represent a three dimensional analog of a classically chaotic system. Patterns of reflected light are shown to produce fractals, and the behavior of the fractal dimension D F is shown to depend on the light's ability to escape the apparatus. The classically chaotic system is then used to investigate the conductance properties of semiconductor heterostructures engineered to produce a conducting plane relatively free of impurities and defects. Introducing walls that inhibit conduction to partition off sections considerably smaller than the mean distance between impurities defines devices called 'billiards'. Cooling to low temperatures enables the electrons traveling through the billiard to maintain quantum mechanical phase. Exposure to a changing electric or magnetic field alters the electron's phase, leading to fluctuations in the conductance through the billiard. Magnetoconductance fluctuations in billiards have previously been shown to be fractal. This behavior has been charted using an empirical parameter, Q, that is a measure of the resolution of the energy levels within the billiard. The relationship with Q is shown to extend beyond the ballistic regime into the 'quasi-ballistic' and 'diffusive' regimes, characterized by having defects within the conduction plane. A model analogous to the classically chaotic system is proposed as the origin of the fractal conductance fluctuations. This model is shown to be consistent with experiment and to account for changes of fine scale features in MCF known to occur when a billiard is brought to room temperature between low temperature measurements. An experiment is conducted in which fractal conductance fluctuations (FCF) are produced by exposing a billiard to a changing electric field. Comparison of DF values of FCF produced by

  7. Property analysis of colloidal quantum dot in semiconductor nanostructure

    Science.gov (United States)

    Mary, Nusrat Irin Chowdhury; Islam, Md. Ariful

    2017-12-01

    Colloidal Quantum Dots (Semiconductor self-assembled QD), as a result of their fully quantized electronic states and high radiative efficiencies, which enable major advances in fundamental physics studies of electrons in zero-dimensionality semiconductor systems and in a variety of novel device applications. This paper reviews the analysis, covering the simulation reading of conical quantum dot with both-single QD and multi-layer QD structure as well as the analytical model for exploration of conical QD waveshape of the quantum-confined systems with different light polarized absorption and sweep parameters. The corresponding temperature of the electron Fermi level with different boundary conditions with the X, Y, and Z - dimensional of the QD conical structure is a responsible for unlike eigen-energy states. The paper shows a comprehensive understanding of the quantum confined 0D electronic structure with its conduction and valence energy band and with varying eigen-energy states, this dynamic process underpins the various device applications.

  8. Fast gain and phase recovery of semiconductor optical amplifiers based on submonolayer quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Herzog, Bastian, E-mail: BHerzog@physik.tu-berlin.de; Owschimikow, Nina; Kaptan, Yücel; Kolarczik, Mirco; Switaiski, Thomas; Woggon, Ulrike [Institut für Optik und Atomare Physik, Technische Universität Berlin, Straße des 17. Juni 135, 10623 Berlin (Germany); Schulze, Jan-Hindrik; Rosales, Ricardo; Strittmatter, André; Bimberg, Dieter; Pohl, Udo W. [Institut für Festkörperphysik, Technische Universität Berlin, Hardenbergstrasse 36, 10623 Berlin (Germany)

    2015-11-16

    Submonolayer quantum dots as active medium in opto-electronic devices promise to combine the high density of states of quantum wells with the fast recovery dynamics of self-assembled quantum dots. We investigate the gain and phase recovery dynamics of a semiconductor optical amplifier based on InAs submonolayer quantum dots in the regime of linear operation by one- and two-color heterodyne pump-probe spectroscopy. We find an as fast recovery dynamics as for quantum dot-in-a-well structures, reaching 2 ps at moderate injection currents. The effective quantum well embedding the submonolayer quantum dots acts as a fast and efficient carrier reservoir.

  9. Calculation of the thermal mode in semiconductor devices in conditions of their operation in semiconductor apparatuses

    OpenAIRE

    Сосков, Анатолій Георгійович; Глєбова, Марина Леонідівна; Сабалаєва, Наталія Олегівна; Форкун, Яна Борисівна

    2014-01-01

    The study of the temperature field of power semiconductor devices, operating in semiconductor apparatuses, either non-contact or hybrid was carried out in the paper.It was also shown that the main mode of the current load of power semiconductor devices, operating in semiconductor apparatuses is a pulse mode.Analytical method for calculating the values of the temperature rise in the structure of power semiconductor devices when subjected to a current pulse of arbitrary shape based on a model t...

  10. Si-semiconductor device failure mechanisms

    International Nuclear Information System (INIS)

    Clauss, H.

    1976-12-01

    This report presents investigations on failure mechanisms that may cause defects during production and operation of silicon semiconductor devices. The failure analysis of aluminium metallization defects covers topics such as step coverage, dissolution pits and electromigration. Furthermore, the generation of process induced lattice defects was investigated. Improved processes avoiding those defects were developed. (orig.) [de

  11. Semiconductor devices for all-optical regeneration

    DEFF Research Database (Denmark)

    Öhman, Filip; Bischoff, Svend; Tromborg, Bjarne

    2003-01-01

    We review different implementations of semiconductor devices for all-optical regeneration. A general model will be presented for all-optical regeneration in fiber links, taking into consideration the trade-off between non-linearity and noise. Furthermore we discuss a novel regenerator type, based...

  12. All optical regeneration using semiconductor devices

    DEFF Research Database (Denmark)

    Mørk, Jesper; Öhman, Filip; Tromborg, Bjarne

    All-optical regeneration is a key functionality for implementing all-optical networks. We present a simple theory for the bit-error-rate in links employing all-optical regenerators, which elucidates the interplay between the noise and and nonlinearity of the regenerator. A novel device structure ...... is analyzed, emphasizing general aspects of active semiconductor waveguides....

  13. Method for manufacturing a semiconductor device

    NARCIS (Netherlands)

    Ishihara, R.; Baiano, A.

    2009-01-01

    The invention relates to a method for manufacturing a semiconductor device on a substrate provided with a silicon-oxide layer, by forming at least one hole in said silicon-oxide layer and depositing on said silicon-oxide layer an amorphous silicon-film which fills said at least one hole and covers a

  14. A theoretical study of the influence of barrier thickness variations on optical properties of a semiconductor multiple quantum well slow light device

    Science.gov (United States)

    Abdolhosseini, S.; Kaatuzian, H.; Kohandani, R.; Choupanzadeh, B.

    2018-01-01

    The influence of barrier thickness variations on the operation of GaAs/AlGaAs multiple quantum well (MQW) slow light devices based on coherence population oscillations (CPOs) is explained. The variations are shown to affect the slow down factor (SDF) and bandwidth of these devices. Bloch equations and the analytical model in fractional dimension are used to analyse and simulate the slow light device. It is shown that other physical parameters of MQW structures (QW width and barrier alloy concentration) affect significantly the optical properties of the device. The presented approaches make it possible to achieve suitable values of SDF and focal energy by adjusting the barrier thickness, QW width and aluminium content. The maximum range of the centre frequency tuning is estimated to be about 1 THz in our calculations, while the slow down factor can reach a high value of 8.5 × 104.

  15. Guiding effect of quantum wells in semiconductor lasers

    Energy Technology Data Exchange (ETDEWEB)

    Aleshkin, V Ya; Dikareva, Natalia V; Dubinov, A A; Zvonkov, B N; Karzanova, Maria V; Kudryavtsev, K E; Nekorkin, S M; Yablonskii, A N

    2013-05-31

    The guiding effect of InGaAs quantum wells in GaAs- and InP-based semiconductor lasers has been studied theoretically and experimentally. The results demonstrate that such waveguides can be effectively used in laser structures with a large refractive index difference between the quantum well material and semiconductor matrix and a large number of quantum wells (e.g. in InP-based structures). (semiconductor lasers. physics and technology)

  16. Electrical Characterization of Semiconductor Materials and Devices

    Science.gov (United States)

    Deen, M.; Pascal, Fabien

    Semiconductor materials and devices continue to occupy a preeminent technological position due to their importance when building integrated electronic systems used in a wide range of applications from computers, cell-phones, personal digital assistants, digital cameras and electronic entertainment systems, to electronic instrumentation for medical diagnositics and environmental monitoring. Key ingredients of this technological dominance have been the rapid advances made in the quality and processing of materials - semiconductors, conductors and dielectrics - which have given metal oxide semiconductor device technology its important characteristics of negligible standby power dissipation, good input-output isolation, surface potential control and reliable operation. However, when assessing material quality and device reliability, it is important to have fast, nondestructive, accurate and easy-to-use electrical characterization techniques available, so that important parameters such as carrier doping density, type and mobility of carriers, interface quality, oxide trap density, semiconductor bulk defect density, contact and other parasitic resistances and oxide electrical integrity can be determined. This chapter describes some of the more widely employed and popular techniques that are used to determine these important parameters. The techniques presented in this chapter range in both complexity and test structure requirements from simple current-voltage measurements to more sophisticated low-frequency noise, charge pumping and deep-level transient spectroscopy techniques.

  17. Hot carrier degradation in semiconductor devices

    CERN Document Server

    2015-01-01

    This book provides readers with a variety of tools to address the challenges posed by hot carrier degradation, one of today’s most complicated reliability issues in semiconductor devices.  Coverage includes an explanation of carrier transport within devices and book-keeping of how they acquire energy (“become hot”), interaction of an ensemble of colder and hotter carriers with defect precursors, which eventually leads to the creation of a defect, and a description of how these defects interact with the device, degrading its performance. • Describes the intricacies of hot carrier degradation in modern semiconductor technologies; • Covers the entire hot carrier degradation phenomenon, including topics such as characterization, carrier transport, carrier-defect interaction, technological impact, circuit impact, etc.; • Enables detailed understanding of carrier transport, interaction of the carrier ensemble with the defect precursors, and an accurate assessment of how the newly created defects imp...

  18. Activation of molecular catalysts using semiconductor quantum dots

    Science.gov (United States)

    Meyer, Thomas J [Chapel Hill, NC; Sykora, Milan [Los Alamos, NM; Klimov, Victor I [Los Alamos, NM

    2011-10-04

    Photocatalytic materials based on coupling of semiconductor nanocrystalline quantum dots (NQD) and molecular catalysts. These materials have capability to drive or catalyze non-spontaneous chemical reactions in the presence of visible radiation, ultraviolet radiation, or both. The NQD functions in these materials as a light absorber and charge generator. Following light absorption, the NQD activates a molecular catalyst adsorbed on the surface of the NQD via transfer of one or more charges (either electrons or electron-holes) from the NQD to the molecular catalyst. The activated molecular catalyst can then drive a chemical reaction. A photoelectrolytic device that includes such photocatalytic materials is also described.

  19. Computer-automated tuning of semiconductor double quantum dots into the single-electron regime

    Energy Technology Data Exchange (ETDEWEB)

    Baart, T. A.; Vandersypen, L. M. K. [QuTech, Delft University of Technology, P.O. Box 5046, 2600 GA Delft (Netherlands); Kavli Institute of Nanoscience, Delft University of Technology, P.O. Box 5046, 2600 GA Delft (Netherlands); Eendebak, P. T. [QuTech, Delft University of Technology, P.O. Box 5046, 2600 GA Delft (Netherlands); Netherlands Organisation for Applied Scientific Research (TNO), P.O. Box 155, 2600 AD Delft (Netherlands); Reichl, C.; Wegscheider, W. [Solid State Physics Laboratory, ETH Zürich, 8093 Zürich (Switzerland)

    2016-05-23

    We report the computer-automated tuning of gate-defined semiconductor double quantum dots in GaAs heterostructures. We benchmark the algorithm by creating three double quantum dots inside a linear array of four quantum dots. The algorithm sets the correct gate voltages for all the gates to tune the double quantum dots into the single-electron regime. The algorithm only requires (1) prior knowledge of the gate design and (2) the pinch-off value of the single gate T that is shared by all the quantum dots. This work significantly alleviates the user effort required to tune multiple quantum dot devices.

  20. Computational electronics semiclassical and quantum device modeling and simulation

    CERN Document Server

    Vasileska, Dragica; Klimeck, Gerhard

    2010-01-01

    Starting with the simplest semiclassical approaches and ending with the description of complex fully quantum-mechanical methods for quantum transport analysis of state-of-the-art devices, Computational Electronics: Semiclassical and Quantum Device Modeling and Simulation provides a comprehensive overview of the essential techniques and methods for effectively analyzing transport in semiconductor devices. With the transistor reaching its limits and new device designs and paradigms of operation being explored, this timely resource delivers the simulation methods needed to properly model state-of

  1. Semiconductor devices for entangled photon pair generation: a review

    Science.gov (United States)

    Orieux, Adeline; Versteegh, Marijn A. M.; Jöns, Klaus D.; Ducci, Sara

    2017-07-01

    Entanglement is one of the most fascinating properties of quantum mechanical systems; when two particles are entangled the measurement of the properties of one of the two allows the properties of the other to be instantaneously known, whatever the distance separating them. In parallel with fundamental research on the foundations of quantum mechanics performed on complex experimental set-ups, we assist today with bourgeoning of quantum information technologies bound to exploit entanglement for a large variety of applications such as secure communications, metrology and computation. Among the different physical systems under investigation, those involving photonic components are likely to play a central role and in this context semiconductor materials exhibit a huge potential in terms of integration of several quantum components in miniature chips. In this article we review the recent progress in the development of semiconductor devices emitting entangled photons. We will present the physical processes allowing the generation of entanglement and the tools to characterize it; we will give an overview of major recent results of the last few years and highlight perspectives for future developments.

  2. Quantum simulation of a Fermi-Hubbard model using a semiconductor quantum dot array

    Science.gov (United States)

    Hensgens, T.; Fujita, T.; Janssen, L.; Li, Xiao; van Diepen, C. J.; Reichl, C.; Wegscheider, W.; Das Sarma, S.; Vandersypen, L. M. K.

    2017-08-01

    Interacting fermions on a lattice can develop strong quantum correlations, which are the cause of the classical intractability of many exotic phases of matter. Current efforts are directed towards the control of artificial quantum systems that can be made to emulate the underlying Fermi-Hubbard models. Electrostatically confined conduction-band electrons define interacting quantum coherent spin and charge degrees of freedom that allow all-electrical initialization of low-entropy states and readily adhere to the Fermi-Hubbard Hamiltonian. Until now, however, the substantial electrostatic disorder of the solid state has meant that only a few attempts at emulating Fermi-Hubbard physics on solid-state platforms have been made. Here we show that for gate-defined quantum dots this disorder can be suppressed in a controlled manner. Using a semi-automated and scalable set of experimental tools, we homogeneously and independently set up the electron filling and nearest-neighbour tunnel coupling in a semiconductor quantum dot array so as to simulate a Fermi-Hubbard system. With this set-up, we realize a detailed characterization of the collective Coulomb blockade transition, which is the finite-size analogue of the interaction-driven Mott metal-to-insulator transition. As automation and device fabrication of semiconductor quantum dots continue to improve, the ideas presented here will enable the investigation of the physics of ever more complex many-body states using quantum dots.

  3. Quantum simulation of a Fermi-Hubbard model using a semiconductor quantum dot array.

    Science.gov (United States)

    Hensgens, T; Fujita, T; Janssen, L; Li, Xiao; Van Diepen, C J; Reichl, C; Wegscheider, W; Das Sarma, S; Vandersypen, L M K

    2017-08-02

    Interacting fermions on a lattice can develop strong quantum correlations, which are the cause of the classical intractability of many exotic phases of matter. Current efforts are directed towards the control of artificial quantum systems that can be made to emulate the underlying Fermi-Hubbard models. Electrostatically confined conduction-band electrons define interacting quantum coherent spin and charge degrees of freedom that allow all-electrical initialization of low-entropy states and readily adhere to the Fermi-Hubbard Hamiltonian. Until now, however, the substantial electrostatic disorder of the solid state has meant that only a few attempts at emulating Fermi-Hubbard physics on solid-state platforms have been made. Here we show that for gate-defined quantum dots this disorder can be suppressed in a controlled manner. Using a semi-automated and scalable set of experimental tools, we homogeneously and independently set up the electron filling and nearest-neighbour tunnel coupling in a semiconductor quantum dot array so as to simulate a Fermi-Hubbard system. With this set-up, we realize a detailed characterization of the collective Coulomb blockade transition, which is the finite-size analogue of the interaction-driven Mott metal-to-insulator transition. As automation and device fabrication of semiconductor quantum dots continue to improve, the ideas presented here will enable the investigation of the physics of ever more complex many-body states using quantum dots.

  4. Universal quantum computation in a semiconductor quantum wire network

    International Nuclear Information System (INIS)

    Sau, Jay D.; Das Sarma, S.; Tewari, Sumanta

    2010-01-01

    Universal quantum computation (UQC) using Majorana fermions on a two-dimensional topological superconducting (TS) medium remains an outstanding open problem. This is because the quantum gate set that can be generated by braiding of the Majorana fermions does not include any two-qubit gate and also no single-qubit π/8 phase gate. In principle, it is possible to create these crucial extra gates using quantum interference of Majorana fermion currents. However, it is not clear if the motion of the various order parameter defects (vortices, domain walls, etc.), to which the Majorana fermions are bound in a TS medium, can be quantum coherent. We show that these obstacles can be overcome using a semiconductor quantum wire network in the vicinity of an s-wave superconductor, by constructing topologically protected two-qubit gates and any arbitrary single-qubit phase gate in a topologically unprotected manner, which can be error corrected using magic-state distillation. Thus our strategy, using a judicious combination of topologically protected and unprotected gate operations, realizes UQC on a quantum wire network with a remarkably high error threshold of 0.14 as compared to 10 -3 to 10 -4 in ordinary unprotected quantum computation.

  5. Biosensing with Luminescent Semiconductor Quantum Dots

    Directory of Open Access Journals (Sweden)

    Hedi Mattoussi

    2006-08-01

    Full Text Available Luminescent semiconductor nanocrystals or quantum dots (QDs are a recentlydeveloped class of nanomaterial whose unique photophysical properties are helping tocreate a new generation of robust fluorescent biosensors. QD properties of interest forbiosensing include high quantum yields, broad absorption spectra coupled to narrow sizetunablephotoluminescent emissions and exceptional resistance to both photobleaching andchemical degradation. In this review, we examine the progress in adapting QDs for severalpredominantly in vitro biosensing applications including use in immunoassays, asgeneralized probes, in nucleic acid detection and fluorescence resonance energy transfer(FRET - based sensing. We also describe several important considerations when workingwith QDs mainly centered on the choice of material(s and appropriate strategies forattaching biomolecules to the QDs.

  6. III-V semiconductor devices integrated with silicon III-V semiconductor devices integrated with silicon

    Science.gov (United States)

    Hopkinson, Mark; Martin, Trevor; Smowton, Peter

    2013-09-01

    The integration of III-V semiconductor devices with silicon is one of the most topical challenges in current electronic materials research. The combination has the potential to exploit the unique optical and electronic functionality of III-V technology with the signal processing capabilities and advanced low-cost volume production techniques associated with silicon. Key industrial drivers include the use of high mobility III-V channel materials (InGaAs, InAs, InSb) to extend the performance of Si CMOS, the unification of electronics and photonics by combining photonic components (GaAs, InP) with a silicon platform for next-generation optical interconnects and the exploitation of large-area silicon substrates and high-volume Si processing capabilities to meet the challenges of low-cost production, a challenge which is particularly important for GaN-based devices in both power management and lighting applications. The diverse nature of the III-V and Si device approaches, materials technologies and the distinct differences between industrial Si and III-V processing have provided a major barrier to integration in the past. However, advances over the last decade in areas such as die transfer, wafer fusion and epitaxial growth have promoted widespread renewed interest. It is now timely to bring some of these topics together in a special issue covering a range of approaches and materials providing a snapshot of recent progress across the field. The issue opens a paper describing a strategy for the epitaxial integration of photonic devices where Kataria et al describe progress in the lateral overgrowth of InP/Si. As an alternative, Benjoucef and Reithmaier report on the potential of InAs quantum dots grown direct onto Si surfaces whilst Sandall et al describe the properties of similar InAs quantum dots as an optical modulator device. As an alternative to epitaxial integration approaches, Yokoyama et al describe a wafer bonding approach using a buried oxide concept, Corbett

  7. Fano Effect and Quantum Entanglement in Hybrid Semiconductor Quantum Dot-Metal Nanoparticle System.

    Science.gov (United States)

    He, Yong; Zhu, Ka-Di

    2017-06-20

    In this paper, we review the investigation for the light-matter interaction between surface plasmon field in metal nanoparticle (MNP) and the excitons in semiconductor quantum dots (SQDs) in hybrid SQD-MNP system under the full quantum description. The exciton-plasmon interaction gives rise to the modified decay rate and the exciton energy shift which are related to the exciton energy by using a quantum transformation method. We illustrate the responses of the hybrid SQD-MNP system to external field, and reveal Fano effect shown in the absorption spectrum. We demonstrate quantum entanglement between two SQD mediated by surface plasmon field. In the absence of a laser field, concurrence of quantum entanglement will disappear after a few ns. If the laser field is present, the steady states appear, so that quantum entanglement produced will reach a steady-state entanglement. Because one of all optical pathways to induce Fano effect refers to the generation of quantum entangled states, It is shown that the concurrence of quantum entanglement can be obtained by observation for Fano effect. In a hybrid system including two MNP and a SQD, because the two Fano quantum interference processes share a segment of all optical pathways, there is correlation between the Fano effects of the two MNP. The investigations for the light-matter interaction in hybrid SQD-MNP system can pave the way for the development of the optical processing devices and quantum information based on the exciton-plasmon interaction.

  8. Fano Effect and Quantum Entanglement in Hybrid Semiconductor Quantum Dot-Metal Nanoparticle System

    Directory of Open Access Journals (Sweden)

    Yong He

    2017-06-01

    Full Text Available In this paper, we review the investigation for the light-matter interaction between surface plasmon field in metal nanoparticle (MNP and the excitons in semiconductor quantum dots (SQDs in hybrid SQD-MNP system under the full quantum description. The exciton-plasmon interaction gives rise to the modified decay rate and the exciton energy shift which are related to the exciton energy by using a quantum transformation method. We illustrate the responses of the hybrid SQD-MNP system to external field, and reveal Fano effect shown in the absorption spectrum. We demonstrate quantum entanglement between two SQD mediated by surface plasmon field. In the absence of a laser field, concurrence of quantum entanglement will disappear after a few ns. If the laser field is present, the steady states appear, so that quantum entanglement produced will reach a steady-state entanglement. Because one of all optical pathways to induce Fano effect refers to the generation of quantum entangled states, It is shown that the concurrence of quantum entanglement can be obtained by observation for Fano effect. In a hybrid system including two MNP and a SQD, because the two Fano quantum interference processes share a segment of all optical pathways, there is correlation between the Fano effects of the two MNP. The investigations for the light-matter interaction in hybrid SQD-MNP system can pave the way for the development of the optical processing devices and quantum information based on the exciton-plasmon interaction.

  9. Electron transport and coherence in semiconductor quantum dots and rings

    NARCIS (Netherlands)

    Van der Wiel, W.G.

    2002-01-01

    A number of experiments on electron transport and coherence in semiconductor vertical and lateral quantum dots and semiconductor rings is described. Quantum dots are often referred to as "artificial atoms", because of their similarities with real atoms. Examples of such atom-like properties that

  10. Study of radiation effects on semiconductor devices

    International Nuclear Information System (INIS)

    Kuboyama, Satoshi; Shindou, Hiroyuki; Ikeda, Naomi; Iwata, Yoshiyuki; Murakami, Takeshi

    2004-01-01

    Fine structure of the recent semiconductor devices has made them more sensitive to the space radiation environment with trapped high-energy protons and heavy ions. A new failure mode caused by bulk damage had been reported on such devices with small structure, and its effect on commercial synchronous dynamic random access memory (SDRAMs) was analyzed from the irradiation test results performed at Heavy ion Medical Accelerator in Chiba (HIMAC). Single event upset (SEU) data of static random access memory (SRAMs) were also collected to establish the method of estimating the proton-induced SEU rate from the results of heavy ion irradiation tests. (authors)

  11. Technology of quantum devices

    CERN Document Server

    Razeghi, Manijeh

    2009-01-01

    This overview of solid state physics provides up-to-date developments in semiconductors and nanotechnology. Mathematical results are carefully described in a standardized style and notation, while ample problems illustrate principles throughout the text.

  12. The electronic properties of semiconductor quantum dots

    International Nuclear Information System (INIS)

    Barker, J.A.

    2000-10-01

    This work is an investigation into the electronic behaviour of semiconductor quantum dots, particularly self-assembled quantum dot arrays. Processor-efficient models are developed to describe the electronic structure of dots, deriving analytic formulae for the strain tensor, piezoelectric distribution and diffusion- induced evolution of the confinement potential, for dots of arbitrary initial shape and composition profile. These models are then applied to experimental data. Transitions due to individual quantum dots have a narrow linewidth as a result of their discrete density of states. By contrast, quantum dot arrays exhibit inhomogeneous broadening which is generally attributed to size variations between the individual dots in the ensemble. Interpreting the results of double resonance spectroscopy, it is seen that variation in the indium composition of the nominally InAs dots is also present. This result also explains the otherwise confusing relationship between the spread in the ground-state and excited-state transition energies. Careful analysis shows that, in addition to the variations in size and composition, some other as yet unidentified broadening mechanism must also be present. The influence of rapid thermal annealing on dot electronic structure is also considered, finding that the experimentally observed blue-shift and narrowing of the photoluminescence linewidth may both be explained in terms of normal In/Ga interdiffusion. InAs/GaAs self-assembled quantum dots are commonly assumed to have a pyramidal geometry, so that we would expect the energy separation of the ground-state electron and hole levels in the dot to be largest at a positive applied field. This should also be the case for any dot of uniform composition whose shape tapers inwards from base to top, counter to the results of experimental Stark-shift spectroscopy which show a peak transition energy at a negative applied field. It is demonstrated that this inversion of the ground state

  13. 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...

  14. 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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Matocha, Kevin; Chatty, Kiran; Banerjee, Sujit

    2018-01-23

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

  16. Interfacing external quantum devices to a universal quantum computer.

    Science.gov (United States)

    Lagana, Antonio A; Lohe, Max A; von Smekal, Lorenz

    2011-01-01

    We present a scheme to use external quantum devices using the universal quantum computer previously constructed. We thereby show how the universal quantum computer can utilize networked quantum information resources to carry out local computations. Such information may come from specialized quantum devices or even from remote universal quantum computers. We show how to accomplish this by devising universal quantum computer programs that implement well known oracle based quantum algorithms, namely the Deutsch, Deutsch-Jozsa, and the Grover algorithms using external black-box quantum oracle devices. In the process, we demonstrate a method to map existing quantum algorithms onto the universal quantum computer. © 2011 Lagana et al.

  17. Quantum spin transport in semiconductor nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Schindler, Christoph

    2012-05-15

    In this work, we study and quantitatively predict the quantum spin Hall effect, the spin-orbit interaction induced intrinsic spin-Hall effect, spin-orbit induced magnetizations, and spin-polarized electric currents in nanostructured two-dimensional electron or hole gases with and without the presence of magnetic fields. We propose concrete device geometries for the generation, detection, and manipulation of spin polarization and spin-polarized currents. To this end a novel multi-band quantum transport theory, that we termed the multi-scattering Buettiker probe model, is developed. The method treats quantum interference and coherence in open quantum devices on the same footing as incoherent scattering and incorporates inhomogeneous magnetic fields in a gauge-invariant and nonperturbative manner. The spin-orbit interaction parameters that control effects such as band energy spin splittings, g-factors, and spin relaxations are calculated microscopically in terms of an atomistic relativistic tight-binding model. We calculate the transverse electron focusing in external magnetic and electric fields. We have performed detailed studies of the intrinsic spin-Hall effect and its inverse effect in various material systems and geometries. We find a geometry dependent threshold value for the spin-orbit interaction for the inverse intrinsic spin-Hall effect that cannot be met by n-type GaAs structures. We propose geometries that spin polarize electric current in zero magnetic field and analyze the out-of-plane spin polarization by all electrical means. We predict unexpectedly large spin-orbit induced spin-polarization effects in zero magnetic fields that are caused by resonant enhancements of the spin-orbit interaction in specially band engineered and geometrically designed p-type nanostructures. We propose a concrete realization of a spin transistor in HgTe quantum wells, that employs the helical edge channel in the quantum spin Hall effect.

  18. Quantum spin transport in semiconductor nanostructures

    International Nuclear Information System (INIS)

    Schindler, Christoph

    2012-01-01

    In this work, we study and quantitatively predict the quantum spin Hall effect, the spin-orbit interaction induced intrinsic spin-Hall effect, spin-orbit induced magnetizations, and spin-polarized electric currents in nanostructured two-dimensional electron or hole gases with and without the presence of magnetic fields. We propose concrete device geometries for the generation, detection, and manipulation of spin polarization and spin-polarized currents. To this end a novel multi-band quantum transport theory, that we termed the multi-scattering Buettiker probe model, is developed. The method treats quantum interference and coherence in open quantum devices on the same footing as incoherent scattering and incorporates inhomogeneous magnetic fields in a gauge-invariant and nonperturbative manner. The spin-orbit interaction parameters that control effects such as band energy spin splittings, g-factors, and spin relaxations are calculated microscopically in terms of an atomistic relativistic tight-binding model. We calculate the transverse electron focusing in external magnetic and electric fields. We have performed detailed studies of the intrinsic spin-Hall effect and its inverse effect in various material systems and geometries. We find a geometry dependent threshold value for the spin-orbit interaction for the inverse intrinsic spin-Hall effect that cannot be met by n-type GaAs structures. We propose geometries that spin polarize electric current in zero magnetic field and analyze the out-of-plane spin polarization by all electrical means. We predict unexpectedly large spin-orbit induced spin-polarization effects in zero magnetic fields that are caused by resonant enhancements of the spin-orbit interaction in specially band engineered and geometrically designed p-type nanostructures. We propose a concrete realization of a spin transistor in HgTe quantum wells, that employs the helical edge channel in the quantum spin Hall effect.

  19. Semiconductor Nanomembranes for Quantum Photonics: Quantum Light Sources and Optomechanics

    DEFF Research Database (Denmark)

    Liu, Jin

    This thesis describes the fabrication and characterizations of semiconductor nanomembranes, i.e., gallium arsenide (GaAs) photonic crystal (PC) and optomechanical nanomemebranes. Processing techniques are developed and optimized in order to fabricate PC membranes for quantum light sources......-record mechanical Q-factor up to 1 million have been fabricated with two step selective wet etches. These optomechanical naonmembranes exhibit superb performances in cavity optomechanical cooling experiments in which a mechanical mode has been cooled from room temperature to 4 K. The interaction between single...... quantum dots (QDs) and PC cavities has been modeled in the framework of Jaynes-Cummings model (JCM) with the focus on single artificial atom lasers. In the experiments, a highly efficient single photon source with a collection efficiency up to 38% has been achieved and detailed measurements suggest...

  20. Specific heat in diluted magnetic semiconductor quantum ring

    Science.gov (United States)

    Babanlı, A. M.; Ibragimov, B. G.

    2017-11-01

    In the present paper, we have calculated the specific heat and magnetization of a quantum ring of a diluted magnetic semiconductor (DMS) material in the presence of magnetic field. We take into account the effect of Rashba spin-orbital interaction, the exchange interaction and the Zeeman term on the specific heat. We have calculated the energy spectrum of the electrons in diluted magnetic semiconductor quantum ring. Moreover we have calculated the specific heat dependency on the magnetic field and Mn concentration at finite temperature of a diluted magnetic semiconductor quantum ring.

  1. Optical properties of semiconductors quantum microcavity structures

    International Nuclear Information System (INIS)

    Afshar, A.M.

    1996-12-01

    The principal phenomenon investigated in this thesis is vacuum Rabi coupling in semiconductor microcavity structures. In these structures quantum well excitons are embedded in a Fabry - Perot like cavity, defined by two semiconductor dielectric mirrors. In such a system the coupled exciton and cavity photon mode form a mixed - mode polariton, where on - resonance there are two branches, each having 50% exciton and 50% photon character. The separation between the upper and lower branches is a measure of the coupling strength where the strength is dependent on the exciton oscillator strength. This interaction is known as vacuum Rabi coupling, and clear anticrossing is seen when the exciton is tuned through the cavity. In our reflectivity experiments we demonstrate control of the coupling between the cavity mode and the exciton by varying temperature, applied electric or magnetic field. Modelling of the reflectivity spectra and the tuning was done using a Transfer Matrix Reflectivity (TMR) model or a linear dispersion model, where in both cases the excitons are treated as Lorentz oscillators. Temperature tuning is achieved because exciton energy decreases with temperature at a much faster rate than the cavity mode. We have demonstrated vacuum Rabi coupling of the cavity mode with both the heavy - hole and light - hole excitons. Electric field tuning is achieved via the quantum confined Stark effect which decreases the exciton energy with increasing field, whilst at the same time the cavity mode energy remains constant. A study of how the electric field reduction of exciton oscillator strength reduces the vacuum Rabi coupling strength is performed. We report the first observation in a semiconductor structure of motional narrowing, seen in both electric field and in temperature tuning experiments at high magnetic field. In magnetic field studies we show how magnetic field induced increase in exciton oscillator strength affects the vacuum Rabi coupling. We also show by

  2. Aptamer-Modified Semiconductor Quantum Dots for Biosensing Applications

    Directory of Open Access Journals (Sweden)

    Lin Wen

    2017-07-01

    Full Text Available Semiconductor quantum dots have attracted extensive interest in the biosensing area because of their properties, such as narrow and symmetric emission with tunable colors, high quantum yield, high stability and controllable morphology. The introduction of various reactive functional groups on the surface of semiconductor quantum dots allows one to conjugate a spectrum of ligands, antibodies, peptides, or nucleic acids for broader and smarter applications. Among these ligands, aptamers exhibit many advantages including small size, high chemical stability, simple synthesis with high batch-to-batch consistency and convenient modification. More importantly, it is easy to introduce nucleic acid amplification strategies and/or nanomaterials to improve the sensitivity of aptamer-based sensing systems. Therefore, the combination of semiconductor quantum dots and aptamers brings more opportunities in bioanalysis. Here we summarize recent advances on aptamer-functionalized semiconductor quantum dots in biosensing applications. Firstly, we discuss the properties and structure of semiconductor quantum dots and aptamers. Then, the applications of biosensors based on aptamer-modified semiconductor quantum dots by different signal transducing mechanisms, including optical, electrochemical and electrogenerated chemiluminescence approaches, is discussed. Finally, our perspectives on the challenges and opportunities in this promising field are provided.

  3. Aptamer-Modified Semiconductor Quantum Dots for Biosensing Applications.

    Science.gov (United States)

    Wen, Lin; Qiu, Liping; Wu, Yongxiang; Hu, Xiaoxiao; Zhang, Xiaobing

    2017-07-28

    Semiconductor quantum dots have attracted extensive interest in the biosensing area because of their properties, such as narrow and symmetric emission with tunable colors, high quantum yield, high stability and controllable morphology. The introduction of various reactive functional groups on the surface of semiconductor quantum dots allows one to conjugate a spectrum of ligands, antibodies, peptides, or nucleic acids for broader and smarter applications. Among these ligands, aptamers exhibit many advantages including small size, high chemical stability, simple synthesis with high batch-to-batch consistency and convenient modification. More importantly, it is easy to introduce nucleic acid amplification strategies and/or nanomaterials to improve the sensitivity of aptamer-based sensing systems. Therefore, the combination of semiconductor quantum dots and aptamers brings more opportunities in bioanalysis. Here we summarize recent advances on aptamer-functionalized semiconductor quantum dots in biosensing applications. Firstly, we discuss the properties and structure of semiconductor quantum dots and aptamers. Then, the applications of biosensors based on aptamer-modified semiconductor quantum dots by different signal transducing mechanisms, including optical, electrochemical and electrogenerated chemiluminescence approaches, is discussed. Finally, our perspectives on the challenges and opportunities in this promising field are provided.

  4. Strain-tunable quantum dot devices

    International Nuclear Information System (INIS)

    Rastelli, A.; Trotta, R.; Zallo, E.; Atkinson, P.; Magerl, E.; Ding, F.; Plumhof, J.D.; Kumar, S.; Doerr, K.; Schmidt, O.G.

    2011-01-01

    We introduce a new class of quantum dot-based devices, in which the semiconductor structures are integrated on top of piezoelectric actuators. This combination allows on one hand to study in detail the effects produced by variable strains (up to about 0.2%) on the excitonic emission of single quantum dots and on the other to manipulate their electronic- and optical properties to achieve specific requirements. In fact, by combining strain with electric fields we are able to obtain (i) independent control of emission energy and charge-state of a QD, (II) wavelength-tunable single-QD light-emitting diodes and (III) frequency-stabilized sources of single photons at predefined wavelengths. Possible future extensions and applications of this technology will be discussed.

  5. Diamond semiconductor technology for RF device applications

    Science.gov (United States)

    Gurbuz, Yasar; Esame, Onur; Tekin, Ibrahim; Kang, Weng P.; Davidson, Jimmy L.

    2005-07-01

    This paper presents a comprehensive review of diamond electronics from the RF perspective. Our aim was to find and present the potential, limitations and current status of diamond semiconductor devices as well as to investigate its suitability for RF device applications. While doing this, we briefly analysed the physics and chemistry of CVD diamond process for a better understanding of the reasons for the technological challenges of diamond material. This leads to Figure of Merit definitions which forms the basis for a technology choice in an RF device/system (such as transceiver or receiver) structure. Based on our literature survey, we concluded that, despite the technological challenges and few mentioned examples, diamond can seriously be considered as a base material for RF electronics, especially RF power circuits, where the important parameters are high speed, high power density, efficient thermal management and low signal loss in high power/frequencies. Simulation and experimental results are highly regarded for the surface acoustic wave (SAW) and field emission (FE) devices which already occupies space in the RF market and are likely to replace their conventional counterparts. Field effect transistors (FETs) are the most promising active devices and extremely high power densities are extracted (up to 30 W/mm). By the surface channel FET approach 81 GHz operation is developed. Bipolar devices are also promising if the deep doping problem can be solved for operation at room temperature. Pressure, thermal, chemical and acceleration sensors have already been demonstrated using micromachining/MEMS approach, but need more experimental results to better exploit thermal, physical/chemical and electronic properties of diamond.

  6. THERMOELECTRIC SEMICONDUCTOR DEVICE FOR CAUTERY OF BLEEDING

    Directory of Open Access Journals (Sweden)

    Denis V. Yevdulov

    2017-01-01

    Full Text Available Abstract. Objectives The aim of the work is to study the possibilities for using a semiconductor device to cauterise bleeding by means of cooling (cryocautery. Method The study is based on methods for approximate modeling of heat exchange processes. Results The construction of a device for cauterisation of bleeding, the actuating element of which consists of a thermoelectric battery operating in cooling mode at the time of blood flow cautery and in heating mode when removing the device from the damaged area, is considered. A model of a device, realised on the basis of the solution of the problem of solidification of a viscous liquid by the method of L.S. Leibenson, is proposed, taking into account the electro- and thermo-physical characteristics of the thermoelectric battery cold source. As a result of the numerical experiment, the dependence of the duration of the ice crust formation on tissues 1 mm thick (which corresponds to the cauterisation of bleeding is obtained on the value of the supply current of the thermoelectric battery. With increasing current, the duration of the ice crust formation is reduced; this can be of the order of 160 s at 5 A. It was demonstrated that the selection of thermoelectric battery parameters and current should be guided by medical norms and standards in order to avoid frostbite in the tissues adjacent to the bleeding zone. Conclusion The special design of thermoelectric device provides an effective technical means for cauterising bleeding by freezing (cryocautery, providing high intensity of cooling, shortenened thrombus formation duration, and eliminating painful sensations when removing the device from a damaged area. 

  7. Semiconductor Nanowires from Materials Science and Device Physics Perspectives

    Science.gov (United States)

    Samuelson, Lars

    2005-03-01

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

  8. Optical Two-Dimensional Spectroscopy of Disordered Semiconductor Quantum Wells and Quantum Dots

    Energy Technology Data Exchange (ETDEWEB)

    Cundiff, Steven T. [Univ. of Colorado, Boulder, CO (United States)

    2016-05-03

    This final report describes the activities undertaken under grant "Optical Two-Dimensional Spectroscopy of Disordered Semiconductor Quantum Wells and Quantum Dots". The goal of this program was to implement optical 2-dimensional Fourier transform spectroscopy and apply it to electronic excitations, including excitons, in semiconductors. Specifically of interest are quantum wells that exhibit disorder due to well width fluctuations and quantum dots. In both cases, 2-D spectroscopy will provide information regarding coupling among excitonic localization sites.

  9. Exciton absorption of entangled photons in semiconductor quantum wells

    Science.gov (United States)

    Rodriguez, Ferney; Guzman, David; Salazar, Luis; Quiroga, Luis; Condensed Matter Physics Group Team

    2013-03-01

    The dependence of the excitonic two-photon absorption on the quantum correlations (entanglement) of exciting biphotons by a semiconductor quantum well is studied. We show that entangled photon absorption can display very unusual features depending on space-time-polarization biphoton parameters and absorber density of states for both bound exciton states as well as for unbound electron-hole pairs. We report on the connection between biphoton entanglement, as quantified by the Schmidt number, and absorption by a semiconductor quantum well. Comparison between frequency-anti-correlated, unentangled and frequency-correlated biphoton absorption is addressed. We found that exciton oscillator strengths are highly increased when photons arrive almost simultaneously in an entangled state. Two-photon-absorption becomes a highly sensitive probe of photon quantum correlations when narrow semiconductor quantum wells are used as two-photon absorbers. Research funds from Facultad de Ciencias, Universidad de los Andes

  10. Transient electro-thermal modeling of bipolar power semiconductor devices

    CERN Document Server

    Gachovska, Tanya Kirilova; Du, Bin

    2013-01-01

    This book presents physics-based electro-thermal models of bipolar power semiconductor devices including their packages, and describes their implementation in MATLAB and Simulink. It is a continuation of our first book Modeling of Bipolar Power Semiconductor Devices. The device electrical models are developed by subdividing the devices into different regions and the operations in each region, along with the interactions at the interfaces, are analyzed using the basic semiconductor physics equations that govern device behavior. The Fourier series solution is used to solve the ambipolar diffusio

  11. Physical limitations of semiconductor devices defects, reliability and esd protection

    CERN Document Server

    Vashchenko, V A

    2008-01-01

    Provides an important link between the theoretical knowledge in the field of non-linier physics and practical application problems in microelectronics. This title focuses on power semiconductor devices and self-triggering pulsed power devices for ESD protection clamps.

  12. Microwave mediated synthesis of semiconductor quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Afrasiabi, Roodabeh; Sugunan, Abhilash; Shahid, Robina; Toprak, Muhammet S.; Muhammed, Mamoun [Division of Functional Materials, Royal Institute of Technology (KTH), Stockholm (Sweden)

    2012-07-15

    Colloidal quantum dots (QD) have tuneable optoelectronic properties and can be easily handled by simple solution processing techniques, making them very attractive for a wide range of applications. Over the past decade synthesis of morphology controlled high quality (crystalline, monodisperse) colloidal QDs by thermal decomposition of organometallic precursors has matured and is well studied. Recently, synthesis of colloidal QDs by microwave irradiation as heating source is being studied due to the inherently different mechanisms of heat transfer, when compared to solvent convection based heating. Under microwave irradiation, polar precursor molecules directly absorb the microwave energy and heat up more efficiently. Here we report synthesis of colloidal II-VI semiconductor QDs (CdS, CdSe, CdTe) by microwave irradiation and compare it with conventional synthesis based on convection heating. Our findings show that QD synthesis by microwave heating is more efficient and the chalcogenide precursor strongly absorbs the microwave radiation shortening the reaction time and giving a high reaction yield (copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  13. Opto-electronic and quantum transport properties of semiconductor nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Sabathil, M.

    2005-01-01

    In this work a novel and efficient method for the calculation of the ballistic transport properties of open semiconductor nanostructures connected to external reservoirs is presented. It is based on the Green's function formalism and reduces the effort to obtain the transmission and the carrier density to a single solution of a hermitian eigenvalue problem with dimensions proportional to the size of the decoupled device and the multiple inversion of a small matrix with dimensions proportional to the size of the contacts to the leads. Using this method, the 4-band GaAs hole transport through a 2-dimensional three-terminal T-junction device, and the resonant tunneling current through a 3-dimensional InAs quantum dot molecule embedded into an InP heterostructure have been calculated. The further extension of the method into a charge self-consistent scheme enables the efficient prediction of the IV-characteristics of highly doped nanoscale field effect transistors in the ballistic regime, including the influence of quasi bound states and the exchange-correlation interaction. Buettiker probes are used to emulate the effect of inelastic scattering on the current for simple 1D devices, systematically analyzing the dependence of the density of states and the resulting self-consistent potential on the scattering strength. The second major topic of this work is the modeling of the optical response of quantum confined neutral and charged excitons in single and coupled self-assembled InGaAs quantum dots. For this purpose the existing device simulator nextnano{sup 3} has been extended to incorporate particle-particle interactions within the means of density functional theory in local density approximation. In this way the exciton transition energies for neutral and charged excitons as a function of an externally applied electric field have been calculated, revealing a systematic reduction of the intrinsic dipole with the addition of extra holes to the exciton, a finding

  14. Physics of Quantum Structures in Photovoltaic Devices

    Science.gov (United States)

    Raffaelle, Ryne P.; Andersen, John D.

    2005-01-01

    There has been considerable activity recently regarding the possibilities of using various nanostructures and nanomaterials to improve photovoltaic conversion of solar energy. Recent theoretical results indicate that dramatic improvements in device efficiency may be attainable through the use of three-dimensional arrays of zero-dimensional conductors (i.e., quantum dots) in an ordinary p-i-n solar cell structure. Quantum dots and other nanostructured materials may also prove to have some benefits in terms of temperature coefficients and radiation degradation associated with space solar cells. Two-dimensional semiconductor superlattices have already demonstrated some advantages in this regard. It has also recently been demonstrated that semiconducting quantum dots can also be used to improve conversion efficiencies in polymeric thin film solar cells. Improvement in thin film cells utilizing conjugated polymers has also be achieved through the use of one-dimensional quantum structures such as carbon nanotubes. It is believed that carbon nanotubes may contribute to both the disassociation as well as the carrier transport in the conjugated polymers used in certain thin film photovoltaic cells. In this paper we will review the underlying physics governing some of the new photovoltaic nanostructures being pursued, as well as the the current methods being employed to produce III-V, II-VI, and even chalcopyrite-based nanomaterials and nanostructures for solar cells.

  15. Polarization-insensitive quantum-dot coupled quantum-well semiconductor optical amplifier

    International Nuclear Information System (INIS)

    Huang Lirong; Yu Yi; Tian Peng; Huang Dexiu

    2009-01-01

    The optical gain of a quantum-dot semiconductor optical amplifier is usually seriously dependent on polarization; we propose a quantum-dot coupled tensile-strained quantum-well structure to obtain polarization insensitivity. The tensile-strained quantum well not only serves as a carrier injection layer of quantum dots but also offers gain to the transverse-magnetic mode. Based on the polarization-dependent coupled carrier rate-equation model, we study carrier competition among quantum well and quantum dots, and study the polarization dependence of the quantum-dot coupled quantum-well semiconductor optical amplifier. We also analyze polarization-dependent photon-mediated carrier distribution among quantum well and quantum dots. It is shown that polarization-insensitive gain can be realized by optimal design

  16. Iterative solution of the semiconductor device equations

    Energy Technology Data Exchange (ETDEWEB)

    Bova, S.W.; Carey, G.F. [Univ. of Texas, Austin, TX (United States)

    1996-12-31

    Most semiconductor device models can be described by a nonlinear Poisson equation for the electrostatic potential coupled to a system of convection-reaction-diffusion equations for the transport of charge and energy. These equations are typically solved in a decoupled fashion and e.g. Newton`s method is used to obtain the resulting sequences of linear systems. The Poisson problem leads to a symmetric, positive definite system which we solve iteratively using conjugate gradient. The transport equations lead to nonsymmetric, indefinite systems, thereby complicating the selection of an appropriate iterative method. Moreover, their solutions exhibit steep layers and are subject to numerical oscillations and instabilities if standard Galerkin-type discretization strategies are used. In the present study, we use an upwind finite element technique for the transport equations. We also evaluate the performance of different iterative methods for the transport equations and investigate various preconditioners for a few generalized gradient methods. Numerical examples are given for a representative two-dimensional depletion MOSFET.

  17. Charge transport in nanoscale lateral and vertical organic semiconductor devices

    NARCIS (Netherlands)

    Xu, Bojian

    2017-01-01

    Organic semiconductors have been drawing more and more attention due to their huge potential for low-cost, flexible, printable electronics and spintronics. In this thesis research, we have investigated charge transport in two organic semiconductors, DXP and P3HT, in different device configurations.

  18. Light Emission and Energy Transfer in Nanoscale Semiconductor Photonic Devices

    National Research Council Canada - National Science Library

    Kolbas, Robert

    1997-01-01

    The overall objective of this experimental program is to control the light emission properties and energy transfer mechanisms in nanoscale semiconductor structures in order to realize new or improved photonic devices...

  19. Development of a multi-physics simulation framework for semiconductor materials and devices

    Science.gov (United States)

    Almeida, Nuno Sucena

    Modern day semiconductor technology devices face the ever increasing issue of accounting for quantum mechanics effects on their modeling and performance assessment. The objective of this work is to create a user-friendly, extensible and powerful multi-physics simulation blackbox for nano-scale semiconductor devices. By using a graphical device modeller this work will provide a friendly environment were a user without deep knowledge of device physics can create a device, simulate it and extract optical and electrical characteristics deemed of interest to his engineering occupation. Resorting to advanced template C++ object-oriented design from the start, this work was able to implement algorithms to simulate 1,2 and 3D devices which along with scripting using the well known Python language enables the user to create batch simulations, to better optimize device performance. Higher-dimensional semiconductors, like wires and dots, require a huge computational cost. MPI parallel libraries enable the software to tackle complex geometries which otherwise would be unfeasible on a small single-CPU computer. Quantum mechanical phenomena is described by Schrodinger's equation which must be solved self-consistently with Poisson's equation for the electrostatic charge and, if required, make use of piezoelectric charge terms from elasticity constraints. Since the software implements a generic n-dimensional FEM engine, virtually any kind of Partial Differential Equation can be solved and in the future, other required solvers besides the ones already implemented will also be included for easy of use. In particular for the semiconductor device physics, we solve the quantum mechanics effective mass conduction-valence band k·p approximation to the Schrodinger-Poisson, in any crystal growth orientation (C,polar M,A and semi-polar planes or any user defined angle) and also include Piezoelectric effects caused by strain in lattice mismatched layers, where the implemented software

  20. Frequency-domain thermal modelling of power semiconductor devices

    DEFF Research Database (Denmark)

    Ma, Ke; Blaabjerg, Frede; Andresen, Markus

    2015-01-01

    to correctly predict the device temperatures, especially when considering the thermal grease and heat sink attached to the power semiconductor devices. In this paper, the frequency-domain approach is applied to the modelling of thermal dynamics for power devices. The limits of the existing RC lump...

  1. Semiconductor terahertz technology devices and systems at room temperature operation

    CERN Document Server

    Carpintero, G; Hartnagel, H; Preu, S; Raisanen, A

    2015-01-01

    Key advances in Semiconductor Terahertz (THz) Technology now promises important new applications enabling scientists and engineers to overcome the challenges of accessing the so-called "terahertz gap".  This pioneering reference explains the fundamental methods and surveys innovative techniques in the generation, detection and processing of THz waves with solid-state devices, as well as illustrating their potential applications in security and telecommunications, among other fields. With contributions from leading experts, Semiconductor Terahertz Technology: Devices and Systems at Room Tempe

  2. 77 FR 19032 - Certain Semiconductor Integrated Circuit Devices and Products Containing Same Notice of Receipt...

    Science.gov (United States)

    2012-03-29

    ... INTERNATIONAL TRADE COMMISSION [DN 2888] Certain Semiconductor Integrated Circuit Devices and... the U.S. International Trade Commission has received a complaint entitled Certain Semiconductor... importation of certain semiconductor integrated circuit devices and products containing same. The complaint...

  3. Separating semiconductor devices from substrate by etching graded composition release layer disposed between semiconductor devices and substrate including forming protuberances that reduce stiction

    Science.gov (United States)

    Tauke-Pedretti, Anna; Nielson, Gregory N; Cederberg, Jeffrey G; Cruz-Campa, Jose Luis

    2015-05-12

    A method includes etching a release layer that is coupled between a plurality of semiconductor devices and a substrate with an etch. The etching includes etching the release layer between the semiconductor devices and the substrate until the semiconductor devices are at least substantially released from the substrate. The etching also includes etching a protuberance in the release layer between each of the semiconductor devices and the substrate. The etch is stopped while the protuberances remain between each of the semiconductor devices and the substrate. The method also includes separating the semiconductor devices from the substrate. Other methods and apparatus are also disclosed.

  4. Simulation of neutron radiation damage in silicon semiconductor devices.

    Energy Technology Data Exchange (ETDEWEB)

    Shadid, John Nicolas; Hoekstra, Robert John; Hennigan, Gary Lee; Castro, Joseph Pete Jr.; Fixel, Deborah A.

    2007-10-01

    A code, Charon, is described which simulates the effects that neutron damage has on silicon semiconductor devices. The code uses a stabilized, finite-element discretization of the semiconductor drift-diffusion equations. The mathematical model used to simulate semiconductor devices in both normal and radiation environments will be described. Modeling of defect complexes is accomplished by adding an additional drift-diffusion equation for each of the defect species. Additionally, details are given describing how Charon can efficiently solve very large problems using modern parallel computers. Comparison between Charon and experiment will be given, as well as comparison with results from commercially-available TCAD codes.

  5. Quantum statistical theory of semiconductor junctions in thermal equilibrium

    Science.gov (United States)

    Von Roos, O.

    1977-01-01

    Free carrier and electric field distributions of one-dimensional semiconductor junctions are evaluated using a quantum mechanical phase-space distribution and its corresponding Boltzmann equation. Attention is given to quantum and exchange corrections in cases of high doping concentrations when carrier densities become degenerate. Quantitative differences between degenerate and classical junction characteristics, e.g., maximum electric field and built-in voltage and carrier concentration within the transition region, are evaluated numerically.

  6. Quantum-size-controlled photoelectrochemical etching of semiconductor nanostructures

    Science.gov (United States)

    Fischer, Arthur J.; Tsao, Jeffrey Y.; Wierer, Jr., Jonathan J.; Xiao, Xiaoyin; Wang, George T.

    2016-03-01

    Quantum-size-controlled photoelectrochemical (QSC-PEC) etching provides a new route to the precision fabrication of epitaxial semiconductor nanostructures in the sub-10-nm size regime. For example, quantum dots (QDs) can be QSC-PEC-etched from epitaxial InGaN thin films using narrowband laser photoexcitation, and the QD sizes (and hence bandgaps and photoluminescence wavelengths) are determined by the photoexcitation wavelength.

  7. Exploring semiconductor quantum dots and wires by high resolution electron microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Molina, S I [Departamento de Ciencia de los Materiales e Ing Metalurgica y Q. Inorganica, F. de Ciencias, Universidad de Cadiz, Campus Rio San Pedro. 11510 Puerto Real (Cadiz) (Spain); Galindo, P L [Departamento de Lenguajes y Sistemas Informaticos, CASEM, Universidad de Cadiz, Campus Rio San Pedro. 11510 Puerto Real (Cadiz) (Spain); Gonzalez, L; Ripalda, J M [Instituto de Microelectronica de Madrid (CNM, CSIC), Isaac Newton 8, 28760 Tres Cantos, Madrid (Spain); Varela, M; Pennycook, S J, E-mail: sergio.molina@uca.e [Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge TN 37831 (United States)

    2010-02-01

    We review in this communication our contribution to the structural characterisation of semiconductor quantum dots and wires by high resolution electron microscopy, both in phase-contrast and Z-contrast modes. We show how these techniques contribute to predict the preferential sites of nucleation of these nanostructures, and also determine the compositional distribution in 1D and 0D nanostructures. The results presented here were produced in the framework of the European Network of Excellence entitled {sup S}elf-Assembled semiconductor Nanostructures for new Devices in photonics and Electronics (SANDiE){sup .}

  8. Spin Splitting in Different Semiconductor Quantum Wells

    International Nuclear Information System (INIS)

    Hao Yafei

    2012-01-01

    We theoretically investigate the spin splitting in four undoped asymmetric quantum wells in the absence of external electric field and magnetic field. The quantum well geometry dependence of spin splitting is studied with the Rashba and the Dresselhaus spin-orbit coupling included. The results show that the structure of quantum well plays an important role in spin splitting. The Rashba and the Dresselhaus spin splitting in four asymmetric quantum wells are quite different. The origin of the distinction is discussed in this work. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

  9. Formation of strain-induced quantum dots in gated semiconductor nanostructures

    Directory of Open Access Journals (Sweden)

    Ted Thorbeck

    2015-08-01

    Full Text Available A long-standing mystery in the field of semiconductor quantum dots (QDs is: Why are there so many unintentional dots (also known as disorder dots which are neither expected nor controllable. It is typically assumed that these unintentional dots are due to charged defects, however the frequency and predictability of the location of the unintentional QDs suggests there might be additional mechanisms causing the unintentional QDs besides charged defects. We show that the typical strains in a semiconductor nanostructure from metal gates are large enough to create strain-induced quantum dots. We simulate a commonly used QD device architecture, metal gates on bulk silicon, and show the formation of strain-induced QDs. The strain-induced QD can be eliminated by replacing the metal gates with poly-silicon gates. Thus strain can be as important as electrostatics to QD device operation operation.

  10. Ultrafast Dynamics of Quantum-Dot Semiconductor Optical Amplifiers

    DEFF Research Database (Denmark)

    Poel, Mike van der; Hvam, Jørn Märcher

    2007-01-01

    We report on a series of experiments on the dynamical properties of quantum-dot semiconductor optical amplifiers. We show how the amplifier responds to one or several ultrafast (170 fs) pulses in rapid succession and our results demonstrate applicability and ultimate limitations to application...

  11. Magnetospatial dispersion of semiconductor quantum wells

    Science.gov (United States)

    Kotova, L. V.; Kats, V. N.; Platonov, A. V.; Kochereshko, V. P.; André, R.; Golub, L. E.

    2018-03-01

    Polarization conversion of light reflected from quantum wells governed by both magnetic field and light propagation direction is observed. We demonstrate that the polarization conversion is caused by the magnetospatial dispersion in quantum wells which manifests itself in the reflection coefficient contribution bilinear in the in-plane components of the magnetic field and the light wave vector. The magnetospatial dispersion is shown to arise due to structure inversion asymmetry of the quantum wells. The effect is resonantly enhanced in the vicinity of the heavy-hole exciton. We show that microscopically the magnetospatial dispersion is caused by the mixing of heavy- and light-hole states in the quantum well due to both orbital effect of the magnetic field and the in-plane hole motion. The degree of the structure inversion asymmetry is determined for GaAs/AlGaAs and CdTe quantum wells.

  12. Quantum computation in semiconductor quantum dots of electron-spin asymmetric anisotropic exchange

    International Nuclear Information System (INIS)

    Hao Xiang; Zhu Shiqun

    2007-01-01

    The universal quantum computation is obtained when there exists asymmetric anisotropic exchange between electron spins in coupled semiconductor quantum dots. The asymmetric Heisenberg model can be transformed into the isotropic model through the control of two local unitary rotations for the realization of essential quantum gates. The rotations on each qubit are symmetrical and depend on the strength and orientation of asymmetric exchange. The implementation of the axially symmetric local magnetic fields can assist the construction of quantum logic gates in anisotropic coupled quantum dots. This proposal can efficiently use each physical electron spin as a logical qubit in the universal quantum computation

  13. 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

  14. Tunnelling and relaxation in semiconductor double quantum wells

    International Nuclear Information System (INIS)

    Ferreira, R.; Bastard, G.

    1997-01-01

    Double quantum wells are among the simplest semiconductor heterostructures exhibiting tunnel coupling. The existence of a quantum confinement effect for the energy levels of a narrow single quantum well has been largely studied. In double quantum wells, in addition to these confinement effects which characterize the levels of the isolated wells, one faces the problem of describing the eigenstates of systems interacting weakly through a potential barrier. In addition, the actual structures differ from the ideal systems studied in the quantum mechanics textbooks in many aspects. The presence of defects leads, for instance, to an irreversible time evolution for a population of photocreated carriers. This irreversible transfer is now clearly established experimentally. The resonant behaviour of the transfer has also been evidenced, from the study of biased structures. If the existence of an interwell transfer is now clearly established from the experimental point of view, its theoretical description, however, is not fully satisfactory. This review focuses on the theoretical description of the energy levels and of the interwell assisted transfer in double quantum wells. We shall firstly outline the problem of tunnel coupling in semiconductor heterostructures and then discuss the single particle and exciton eigenstates in double quantum wells. In the remaining part of the review we shall present and critically review a few theoretical models used to describe the assisted interwell transfer in these structures. (author)

  15. Wonder of nanotechnology quantum optoelectronic devices and applications

    CERN Document Server

    Razeghi, Manijeh; von Klitzing, Klaus

    2013-01-01

    When you look closely, Nature is nanotechnology at its finest. From a single cell, a factory all by itself, to complex systems, such as the nervous system or the human eye, each is composed of specialized nanostructures that exist to perform a specific function. This same beauty can be mirrored when we interact with the tiny physical world that is the realm of quantum mechanics.The Wonder of Nanotechnology: Quantum Optoelectronic Devices and Applications, edited by Manijeh Razeghi, Leo Esaki, and Klaus von Klitzing focuses on the application of nanotechnology to modern semiconductor optoelectr

  16. Pulse train amplification and regeneration based on semiconductor quantum dots waveguide

    DEFF Research Database (Denmark)

    Chen, Yaohui; Öhman, Filip; Mørk, Jesper

    2008-01-01

    We numerical analyze pulse train amplification up to 200 Gbit/s in quantum dot amplifiers and present regeneration properties with saturable absorber based on semiconductor quantum dot waveguides.......We numerical analyze pulse train amplification up to 200 Gbit/s in quantum dot amplifiers and present regeneration properties with saturable absorber based on semiconductor quantum dot waveguides....

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

    CERN Document Server

    Pearton, Stephen

    2013-01-01

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

  18. 3D TCAD Simulation for Semiconductor Processes, Devices and Optoelectronics

    CERN Document Server

    Li, Simon

    2012-01-01

    Technology computer-aided design, or TCAD, is critical to today’s semiconductor technology and anybody working in this industry needs to know something about TCAD.  This book is about how to use computer software to manufacture and test virtually semiconductor devices in 3D.  It brings to life the topic of semiconductor device physics, with a hands-on, tutorial approach that de-emphasizes abstract physics and equations and emphasizes real practice and extensive illustrations.  Coverage includes a comprehensive library of devices, representing the state of the art technology, such as SuperJunction LDMOS, GaN LED devices, etc. Provides a vivid, internal view of semiconductor devices, through 3D TCAD simulation; Includes comprehensive coverage of  TCAD simulations for both optic and electronic devices, from nano-scale to high-voltage high-power devices; Presents material in a hands-on, tutorial fashion so that industry practitioners will find maximum utility; Includes a comprehensive library of devices, re...

  19. Handbook of compound semiconductors growth, processing, characterization, and devices

    CERN Document Server

    Holloway, Paul H

    1996-01-01

    This book reviews the recent advances and current technologies used to produce microelectronic and optoelectronic devices from compound semiconductors. It provides a complete overview of the technologies necessary to grow bulk single-crystal substrates, grow hetero-or homoepitaxial films, and process advanced devices such as HBT's, QW diode lasers, etc.

  20. Dimensionality effects on the conductance of semiconductor quantum wires

    International Nuclear Information System (INIS)

    Dacal, Luis C.O.; Damiao, Alvaro Jose; Andrada e Silva, E.A. de

    2004-01-01

    Full text: 'Spintronics' is a new kind of electronics based on the spin instead of charge of electrons [1]. It opens the possibility for faster devices and reduction of power consuming. This new field of research has received great attention from scientists in recent years [2]. Within the Kane model, spin-orbit interaction couples the three spatial coordinates dynamics for electrons in semiconductor heterostructures [3]. As a consequence, the control of spin transport in semiconductor nanostructures requires a three-dimensional description of the system. Strictly two-dimensional (2D) and three-dimensional (3D) descriptions are known in literature [4], but no attention has been devoted to the transition between them. In this work, we address this question calculating the conductance of a quantum wire with infinite contacts in a strictly 2D, quasi-2D and strictly 3D models. This study allows to better understand the mechanisms that contribute to the conductance in absence of spin-orbit interaction. We consider ballistic quantum regime, the same material for contacts and wire and we employ Landauer-Buttiker formula, 'mode matching' technique [4] and envelope function formalism. Our results reproduce the typical conductance oscillations and the well known mode degeneracy for 3D systems [4]. We prove that the critical parameters controlling the amplitude of these oscillations are the ratios between the wire and contacts transversal lengths, while the wire longitudinal length determines the position and shape of the peaks. This work is supported by FAPESP and CNPq. [1] Min Ouyang and David D. Awschalom, Science 301, 1074 (2003); Shuichi Murakami, Naoto Nagaosa, and Shou-Cheng Zhang, Science 301, 1348 (2003) [2] Proceedings of the 2002 PASPS, Wuerzburg, Germany, Journal of Superconductivity, Special Issue, April 2003[3] E. A. de Andrada e Silva, G. C. La Rocca and F. Bassani, Phys. Rev. B 50, 8523 (1994) [4] George Kirczenow, Phys. Rev. B 39, 10452 (1989); Karl

  1. Second-harmonic imaging of semiconductor quantum dots

    DEFF Research Database (Denmark)

    Østergaard, John Erland; Bozhevolnyi, Sergey I.; Pedersen, Kjeld

    2000-01-01

    Resonant second-harmonic generation is observed at room temperature in reflection from self-assembled InAlGaAs quantum dots grown on a GaAs (001) substrate. The detected second-harmonic signal peaks at a pump wavelength of similar to 885 nm corresponding to the quantum-dot photoluminescence maximum....... In addition, the second-harmonic spectrum exhibits another smaller but well-pronounced peak at 765 nm not found in the linear experiments. We attribute this peak to the generation of second-harmonic radiation in the AlGaAs spacer layer enhanced by the local symmetry at the quantum-dot interface. We further...... observe that second-harmonic images of the quantum-dot surface structure show wavelength-dependent spatial variations. Imaging at different wavelength is used to demonstrate second-harmonic generation from the semiconductor quantum dots. (C) 2000 American Institute of Physics....

  2. Closed-loop design of active semiconductor quantum well material systems

    Science.gov (United States)

    Moloney, J. V.; Hader, J.; Koch, S. W.

    2005-10-01

    Semiconductor quantum well active structures are pervasive in many applications of defense related systems ranging from low power edge (DFB), VCSEL and VCSEL emitter arrays to high power low brightness broad area emitters and diode bars. Recent breakthroughs in the development of a new class of high brightness vertical external cavity (VECSEL) emitters offers the potential to replace solid state YAG kW-class laser weapons systems. Remarkably, despite the maturity and dramatic improvement in quality of semiconductor QW growth over the past three decades, there has been no truly predictive means of designing the semiconductor active structure and fast-tracking to a final packaged device. We will describe a fully self-consistent microscopic many-body approach to calculate optical gain, absorption, refractive index spectra and nonradiative recombination rates for a broad class of semiconductor quantum well material systems. The theoretical calculations are free of ad hoc parameter adjustments and provide, for the first time, a means of designing an active semiconductor epi-structure in a predictive manner.

  3. Full quantum treatment of charge dynamics in amorphous molecular semiconductors

    Science.gov (United States)

    de Vries, Xander; Friederich, Pascal; Wenzel, Wolfgang; Coehoorn, Reinder; Bobbert, Peter A.

    2018-02-01

    We present a treatment of charge dynamics in amorphous molecular semiconductors that accounts for the coupling of charges to all intramolecular phonon modes in a fully quantum mechanical way. Based on ab initio calculations, we derive charge transfer rates that improve on the widely used semiclassical Marcus rate and obtain benchmark results for the mobility and energetic relaxation of electrons and holes in three semiconductors commonly applied in organic light-emitting diodes. Surprisingly, we find very similar results when using the simple Miller-Abrahams rate. We conclude that extracting the disorder strength from temperature-dependent charge transport studies is very possible but extracting the reorganization energy is not.

  4. Molecular and polymeric organic semiconductors for applications in photovoltaic devices

    CERN Document Server

    Meinhardt, G

    2000-01-01

    Photovoltaic devices based on molecular as well as polymeric semiconductors were investigated and characterized. The organic materials presented here exhibit the advantages of low price, low processing costs and the possibility of tuning their optical properties. The photovoltaic properties were investigated by photocurrent action spectroscopy and I/V-characterization and the electric field distribution in each layer by electroabsorption spectroscopy. Single layer devices of molecular semiconductors and semiconducting polymers like methyl-substituted polyparaphenylene, CN-Ether-PPV, copper-phthalocyanine, the terryleneimide DOTer, the perylene derivatives BBP-perylene and polyBBP-perylene show low photocurrents as well as a small photovoltaic effect in their pristine form. One way to enhance the performance is to blend the active layer with molecular dopands like a soluble form of titaniumoxophthalocyanine or the aromatic macromolecule RS19 or to combine two organic semiconductors in heterostructure devices. ...

  5. Quantum computing based on semiconductor nanowires

    NARCIS (Netherlands)

    Frolov, S.M.; Plissard, S.R.; Nadj-Perge, S.; Kouwenhoven, L.P.; Bakkers, E.P.A.M.

    2013-01-01

    A quantum computer will have computational power beyond that of conventional computers, which can be exploited for solving important and complex problems, such as predicting the conformations of large biological molecules. Materials play a major role in this emerging technology, as they can enable

  6. Development and Application of Semiconductor Quantum Dots to Quantum Computing

    National Research Council Canada - National Science Library

    Steel, Duncan

    2002-01-01

    .... Several major milestones were achieved during the present program including the demonstration of optically induced and detected quantum entanglement of two qubits, Rabi oscillation (one bit rotation...

  7. QCAD simulation and optimization of semiconductor double quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Nielsen, Erik; Gao, Xujiao; Kalashnikova, Irina; Muller, Richard Partain; Salinger, Andrew Gerhard; Young, Ralph Watson

    2013-12-01

    We present the Quantum Computer Aided Design (QCAD) simulator that targets modeling quantum devices, particularly silicon double quantum dots (DQDs) developed for quantum qubits. The simulator has three di erentiating features: (i) its core contains nonlinear Poisson, e ective mass Schrodinger, and Con guration Interaction solvers that have massively parallel capability for high simulation throughput, and can be run individually or combined self-consistently for 1D/2D/3D quantum devices; (ii) the core solvers show superior convergence even at near-zero-Kelvin temperatures, which is critical for modeling quantum computing devices; (iii) it couples with an optimization engine Dakota that enables optimization of gate voltages in DQDs for multiple desired targets. The Poisson solver includes Maxwell- Boltzmann and Fermi-Dirac statistics, supports Dirichlet, Neumann, interface charge, and Robin boundary conditions, and includes the e ect of dopant incomplete ionization. The solver has shown robust nonlinear convergence even in the milli-Kelvin temperature range, and has been extensively used to quickly obtain the semiclassical electrostatic potential in DQD devices. The self-consistent Schrodinger-Poisson solver has achieved robust and monotonic convergence behavior for 1D/2D/3D quantum devices at very low temperatures by using a predictor-correct iteration scheme. The QCAD simulator enables the calculation of dot-to-gate capacitances, and comparison with experiment and between solvers. It is observed that computed capacitances are in the right ballpark when compared to experiment, and quantum con nement increases capacitance when the number of electrons is xed in a quantum dot. In addition, the coupling of QCAD with Dakota allows to rapidly identify which device layouts are more likely leading to few-electron quantum dots. Very efficient QCAD simulations on a large number of fabricated and proposed Si DQDs have made it possible to provide fast feedback for design

  8. Resistive field structures for semiconductor devices and uses therof

    Science.gov (United States)

    Marinella, Matthew; DasGupta, Sandeepan; Kaplar, Robert; Baca, Albert G.

    2017-09-12

    The present disclosure relates to resistive field structures that provide improved electric field profiles when used with a semiconductor device. In particular, the resistive field structures provide a uniform electric field profile, thereby enhancing breakdown voltage and improving reliability. In example, the structure is a field cage that is configured to be resistive, in which the potential changes significantly over the distance of the cage. In another example, the structure is a resistive field plate. Using these resistive field structures, the characteristics of the electric field profile can be independently modulated from the physical parameters of the semiconductor device. Additional methods and architectures are described herein.

  9. Finite element method for simulation of the semiconductor devices

    International Nuclear Information System (INIS)

    Zikatanov, L.T.; Kaschiev, M.S.

    1991-01-01

    An iterative method for solving the system of nonlinear equations of the drift-diffusion representation for the simulation of the semiconductor devices is worked out. The Petrov-Galerkin method is taken for the discretization of these equations using the bilinear finite elements. It is shown that the numerical scheme is a monotonous one and there are no oscillations of the solutions in the region of p-n transition. The numerical calculations of the simulation of one semiconductor device are presented. 13 refs.; 3 figs

  10. 77 FR 25747 - Certain Semiconductor Integrated Circuit Devices and Products Containing Same; Institution of...

    Science.gov (United States)

    2012-05-01

    ... INTERNATIONAL TRADE COMMISSION [Inv. No. 337-TA-840] Certain Semiconductor Integrated Circuit... States after importation of certain semiconductor integrated circuit devices and products containing same... importation, or the sale within the United States after importation of certain semiconductor integrated...

  11. THz quantum-confined Stark effect in semiconductor quantum dots

    DEFF Research Database (Denmark)

    Turchinovich, Dmitry; Monozon, Boris S.; Livshits, Daniil A.

    2012-01-01

    We demonstrate an instantaneous all-optical manipulation of optical absorption at the ground state of InGaAs/GaAs quantum dots (QDs) via a quantum-confined Stark effect (QCSE) induced by the electric field of incident THz pulses with peak electric fields reaching 200 kV/cm in the free space...

  12. Dynamics of spins in semiconductor quantum wells under drift

    International Nuclear Information System (INIS)

    Idrish Miah, M.

    2009-01-01

    The dynamics of spins in semiconductor quantum wells under applied electric bias has been investigated by photoluminescence (PL) spectroscopy. The bias-dependent polarization of PL (P PL ) was measured at different temperatures. The P PL was found to decay with an enhancement of increasing the strength of the negative bias, with an exception occurred for a low value of the negative bias. The P PL was also found to depend on the temperature. The P PL in the presence of a transverse magnetic field was also studied. The results showed that P PL in the magnetic field oscillates under an applied bias, demonstrating that the dephasing of electron spin occurs during the drift transport in semiconductor quantum wells.

  13. Dynamics of spins in semiconductor quantum wells under drift

    Energy Technology Data Exchange (ETDEWEB)

    Idrish Miah, M., E-mail: m.miah@griffith.edu.a [Nanoscale Science and Technology Centre, Griffith University, Nathan, Brisbane, QLD 4111 (Australia); School of Biomolecular and Physical Sciences, Griffith University, Nathan, Brisbane, QLD 4111 (Australia); Department of Physics, University of Chittagong, Chittagong 4331 (Bangladesh)

    2009-09-15

    The dynamics of spins in semiconductor quantum wells under applied electric bias has been investigated by photoluminescence (PL) spectroscopy. The bias-dependent polarization of PL (P{sub PL}) was measured at different temperatures. The P{sub PL} was found to decay with an enhancement of increasing the strength of the negative bias, with an exception occurred for a low value of the negative bias. The P{sub PL} was also found to depend on the temperature. The P{sub PL} in the presence of a transverse magnetic field was also studied. The results showed that P{sub PL} in the magnetic field oscillates under an applied bias, demonstrating that the dephasing of electron spin occurs during the drift transport in semiconductor quantum wells.

  14. Single electron-spin memory with a semiconductor quantum dot

    International Nuclear Information System (INIS)

    Young, Robert J; Dewhurst, Samuel J; Stevenson, R Mark; Atkinson, Paola; Bennett, Anthony J; Ward, Martin B; Cooper, Ken; Ritchie, David A; Shields, Andrew J

    2007-01-01

    We show storage of the circular polarization of an optical field, transferring it to the spin-state of an individual electron confined in a single semiconductor quantum dot. The state is subsequently read out through the electronically-triggered emission of a single photon. The emitted photon shares the same polarization as the initial pulse but has a different energy, making the transfer of quantum information between different physical systems possible. With an applied magnetic field of 2 T, spin memory is preserved for at least 1000 times more than the exciton's radiative lifetime

  15. Electron Liquids in Semiconductor Quantum Structures

    International Nuclear Information System (INIS)

    Pinczuk, Aron

    2009-01-01

    The groups led by Stormer and Pinczuk have focused this project on goals that seek the elucidation of novel many-particle effects that emerge in two-dimensional electron systems (2DES) as the result from fundamental quantum interactions. This experimental research is conducted under extreme conditions of temperature and magnetic field. From the materials point of view, the ultra-high mobility systems in GaAs/AlGaAs quantum structures continue to be at the forefront of this research. The newcomer materials are based on graphene, a single atomic layer of graphite. The graphene research is attracting enormous attention from many communities involved in condensed matter research. The investigated many-particle phenomena include the integer and fractional quantum Hall effect, composite fermions, and Dirac fermions, and a diverse group of electron solid and liquid crystal phases. The Stormer group performed magneto-transport experiments and far-infrared spectroscopy, while the Pinczuk group explores manifestations of such phases in optical spectra.

  16. Electron Liquids in Semiconductor Quantum Structures

    Energy Technology Data Exchange (ETDEWEB)

    Aron Pinczuk

    2009-05-25

    The groups led by Stormer and Pinczuk have focused this project on goals that seek the elucidation of novel many-particle effects that emerge in two-dimensional electron systems (2DES) as the result from fundamental quantum interactions. This experimental research is conducted under extreme conditions of temperature and magnetic field. From the materials point of view, the ultra-high mobility systems in GaAs/AlGaAs quantum structures continue to be at the forefront of this research. The newcomer materials are based on graphene, a single atomic layer of graphite. The graphene research is attracting enormous attention from many communities involved in condensed matter research. The investigated many-particle phenomena include the integer and fractional quantum Hall effect, composite fermions, and Dirac fermions, and a diverse group of electron solid and liquid crystal phases. The Stormer group performed magneto-transport experiments and far-infrared spectroscopy, while the Pinczuk group explores manifestations of such phases in optical spectra.

  17. Computational models for the berry phase in semiconductor quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Prabhakar, S., E-mail: rmelnik@wlu.ca; Melnik, R. V. N., E-mail: rmelnik@wlu.ca [M2NeT Lab, Wilfrid Laurier University, 75 University Ave W, Waterloo, ON N2L 3C5 (Canada); Sebetci, A. [Department of Mechanical Engineering, Mevlana University, 42003, Konya (Turkey)

    2014-10-06

    By developing a new model and its finite element implementation, we analyze the Berry phase low-dimensional semiconductor nanostructures, focusing on quantum dots (QDs). In particular, we solve the Schrödinger equation and investigate the evolution of the spin dynamics during the adiabatic transport of the QDs in the 2D plane along circular trajectory. Based on this study, we reveal that the Berry phase is highly sensitive to the Rashba and Dresselhaus spin-orbit lengths.

  18. Coherently driven semiconductor quantum dot at a telecommunication wavelength.

    Science.gov (United States)

    Takagi, Hiroyuki; Nakaoka, Toshihiro; Watanabe, Katsuyuki; Kumagai, Naoto; Arakawa, Yasuhiko

    2008-09-01

    We proposed and demonstrate use of optical driving pulses at a telecommunication wavelength for exciton-based quantum gate operation. The exciton in a self-assembled quantum dot is coherently manipulated at 1.3 microm through Rabi oscillation. The telecom-band exciton-qubit system incorporates standard optical fibers and fiber optic devices. The coherent manipulation of the two-level system compatible with flexible and stable fiber network paves the way toward practical optical implementation of quantum information processing devices.

  19. Semiconductor Radiation Physics: From Defects to Devices

    National Research Council Canada - National Science Library

    Witt, Gerald L

    2005-01-01

    Radiation effects have been a serious problem for electronics used in defense and space systems for decades and radiation-hardened devices, circuits, and systems have been developed to meet the needs of these systems...

  20. Carrier-phonon interaction in semiconductor quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Seebeck, Jan

    2009-03-10

    In recent years semiconductor quantum dots have been studied extensively due to their wide range of possible applications, predominantly for light sources. For successful applications, efficient carrier scattering processes as well as a detailed understanding of the optical properties are of central importance. The aims of this thesis are theoretical investigations of carrier scattering processes in InGaAs/GaAs quantum dots on a quantum-kinetic basis. A consistent treatment of quasi-particle renormalizations and carrier kinetics for non-equilibrium conditions is presented, using the framework of non-equilibrium Green's functions. The focus of our investigations is the interaction of carriers with LO phonons. Important for the understanding of the scattering mechanism are the corresponding quasi-particle properties. Starting from a detailed study of quantum-dot polarons, scattering and dephasing processes are discussed for different temperature regimes. The inclusion of polaron and memory effects turns out to be essential for the description of the carrier kinetics in quantum-dot systems. They give rise to efficient scattering channels and the obtained results are in agreement with recent experiments. Furthermore, a consistent treatment of the carrier-LO-phonon and the carrier-carrier interaction is presented for the optical response of semiconductor quantum dots, both giving rise to equally important contributions to the dephasing. Beside the conventional GaAs material system, currently GaN based light sources are of high topical interest due to their wide range of possible emission frequencies. In this material additionally intrinsic properties like piezoelectric fields and strong band-mixing effects have to be considered. For the description of the optical properties of InN/GaN quantum dots a procedure is presented, where the material properties obtained from an atomistic tight-binding approach are combined with a many-body theory for non

  1. Third generation photovoltaics based on multiple exciton generation in quantum confined semiconductors.

    Science.gov (United States)

    Beard, Matthew C; Luther, Joseph M; Semonin, Octavi E; Nozik, Arthur J

    2013-06-18

    Improving the primary photoconversion process in a photovoltaiccell by utilizing the excess energy that is otherwise lost as heat can lead to an increase in the overall power conversion efficiency (PCE). Semiconductor nanocrystals (NCs) with at least one dimension small enough to produce quantum confinement effects provide new ways of controlling energy flow not achievable in thin film or bulk semiconductors. Researchers have developed various strategies to incorporate these novel structures into suitable solar conversion systems. Some of these methods could increase the PCE past the Shockley-Queisser (SQ) limit of ∼33%, making them viable "third generation photovoltaic" (TGPV) cell architectures. Surpassing the SQ limit for single junction solar cells presents both a scientific and a technological challenge, and the use of semiconductor NCs to enhance the primary photoconversion process offers a promising potential solution. The NCs are synthesized via solution phase chemical reactions producing stable colloidal solutions, where the reaction conditions can be modified to produce a variety of shapes, compositions, and structures. The confinement of the semiconductor NC in one dimension produces quantum films, wells, or discs. Two-dimensional confinement leads to quantum wires or rods (QRs), and quantum dots (QDs) are three-dimensionally confined NCs. The process of multiple exciton generation (MEG) converts a high-energy photon into multiple electron-hole pairs. Although many studies have demonstrated that MEG is enhanced in QDs compared with bulk semiconductors, these studies have either used ultrafast spectroscopy to measure the photon-to-exciton quantum yields (QYs) or theoretical calculations. Implementing MEG in a working solar cell has been an ongoing challenge. In this Account, we discuss the status of MEG research and strategies towards implementing MEG in working solar cells. Recently we showed an external quantum efficiency for photocurrent of greater

  2. Semiconductor-inspired design principles for superconducting quantum computing.

    Science.gov (United States)

    Shim, Yun-Pil; Tahan, Charles

    2016-03-17

    Superconducting circuits offer tremendous design flexibility in the quantum regime culminating most recently in the demonstration of few qubit systems supposedly approaching the threshold for fault-tolerant quantum information processing. Competition in the solid-state comes from semiconductor qubits, where nature has bestowed some very useful properties which can be utilized for spin qubit-based quantum computing. Here we begin to explore how selective design principles deduced from spin-based systems could be used to advance superconducting qubit science. We take an initial step along this path proposing an encoded qubit approach realizable with state-of-the-art tunable Josephson junction qubits. Our results show that this design philosophy holds promise, enables microwave-free control, and offers a pathway to future qubit designs with new capabilities such as with higher fidelity or, perhaps, operation at higher temperature. The approach is also especially suited to qubits on the basis of variable super-semi junctions.

  3. 77 FR 60721 - Certain Semiconductor Integrated Circuit Devices and Products Containing Same; Notice of...

    Science.gov (United States)

    2012-10-04

    ... INTERNATIONAL TRADE COMMISSION [Investigation No. 337-TA-840] Certain Semiconductor Integrated Circuit Devices and Products Containing Same; Notice of Commission Determination Not To Review an Initial... certain semiconductor integrated circuit devices and products containing same by reason of infringement of...

  4. 77 FR 39510 - Certain Semiconductor Integrated Circuit Devices and Products Containing Same; Determination Not...

    Science.gov (United States)

    2012-07-03

    ... INTERNATIONAL TRADE COMMISSION [Investigation No. 337-TA-840] Certain Semiconductor Integrated Circuit Devices and Products Containing Same; Determination Not To Review an Initial Determination... certain semiconductor integrated circuit devices and products containing same by reason of infringement of...

  5. Semiconductor Nanomembrane-Based Light-Emitting and Photodetecting Devices

    Directory of Open Access Journals (Sweden)

    Dong Liu

    2016-06-01

    Full Text Available Heterogeneous integration between silicon (Si, III-V group material and Germanium (Ge is highly desirable to achieve monolithic photonic circuits. Transfer-printing and stacking between different semiconductor nanomembranes (NMs enables more versatile combinations to realize high-performance light-emitting and photodetecting devices. In this paper, lasers, including vertical and edge-emitting structures, flexible light-emitting diode, photodetectors at visible and infrared wavelengths, as well as flexible photodetectors, are reviewed to demonstrate that the transfer-printed semiconductor nanomembrane stacked layers have a large variety of applications in integrated optoelectronic systems.

  6. Electromagnetic radiation screening of semiconductor devices for long life applications

    Science.gov (United States)

    Hall, T. C.; Brammer, W. G.

    1972-01-01

    A review is presented of the mechanism of interaction of electromagnetic radiation in various spectral ranges, with various semiconductor device defects. Previous work conducted in this area was analyzed as to its pertinence to the current problem. The task was studied of implementing electromagnetic screening methods in the wavelength region determined to be most effective. Both scanning and flooding type stimulation techniques are discussed. While the scanning technique offers a considerably higher yield of useful information, a preliminary investigation utilizing the flooding approach is first recommended because of the ease of implementation, lower cost and ability to provide go-no-go information in semiconductor screening.

  7. Exciton coherence in semiconductor quantum dots

    International Nuclear Information System (INIS)

    Ishi-Hayase, Junko; Akahane, Kouichi; Yamamoto, Naokatsu; Sasaki, Masahide; Kujiraoka, Mamiko; Ema, Kazuhiro

    2009-01-01

    The coherent dynamics of excitons in InAs quantum dots (QDs) was investigated in the telecommunication wavelength range using a transient four-wave mixing technique. The sample was fabricated on an InP(311)B substrate using strain compensation to control the emission wavelength. This technique also enabled us to fabricate a 150-layer stacked QD structure for obtaining a high S/N in the four-wave mixing measurements, although no high-sensitive heterodyne detection was carried out. The dephasing time and transition dipole moment were precisely estimated from the polarization dependence of signals, taking into account their anisotropic properties. The population lifetimes of the excitons were also measured by using a polarization-dependent pumpprobe technique. A quantitative comparison of these anisotropies demonstrates that in our QDs, non-radiative population relaxation, polarization relaxation and pure dephasing are considerably smaller than the radiative relaxation. A comparison of the results of the four-wave mixing and pump-probe measurements revealed that the pure dephasing could be directly estimated with an accuracy of greater than 0.1 meV by comparing the results of four-wave mixing and pump-probe measurements. (copyright 2009 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  8. Impact of Relativistic Electron Beam on Hole Acoustic Instability in Quantum Semiconductor Plasmas

    Science.gov (United States)

    Siddique, M.; Jamil, M.; Rasheed, A.; Areeb, F.; Javed, Asif; Sumera, P.

    2018-01-01

    We studied the influence of the classical relativistic beam of electrons on the hole acoustic wave (HAW) instability exciting in the semiconductor quantum plasmas. We conducted this study by using the quantum-hydrodynamic model of dense plasmas, incorporating the quantum effects of semiconductor plasma species which include degeneracy pressure, exchange-correlation potential and Bohm potential. Analysis of the quantum characteristics of semiconductor plasma species along with relativistic effect of beam electrons on the dispersion relation of the HAW is given in detail qualitatively and quantitatively by plotting them numerically. It is worth mentioning that the relativistic electron beam (REB) stabilises the HAWs exciting in semiconductor (GaAs) degenerate plasma.

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

    Science.gov (United States)

    Singh, Kalpana; Nowotny, Janusz; Thangadurai, Venkataraman

    2013-03-07

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

  10. Optical gain and laser properties of semiconductor quantum-dot systems

    Energy Technology Data Exchange (ETDEWEB)

    Lorke, Michael

    2008-12-17

    For practical applications of quantum dots in light emitters as well as for fundamental studies of their emission properties, the understanding of many-body processes plays a central role. We employ a microscopic theory to study the optical properties of semiconductor quantum dots. The excitation-induced polarization dephasing due to carrier-phonon and carrier-carrier Coulomb interaction as well as the corresponding lineshifts of the optical interband transitions are determined on the basis of a quantum-kinetic treatment of correlation processes. Our theoretical model includes non-Markovian effects as well as renormalized single-particle states. Thus we achieve an accurate description of the partial compensation between different dephasing contributions and are able to systematically study their temperature and density dependencies. Applications of this theoretical model include optical gain spectra for quantum-dot systems that reveal a novel effect, not present in other gain materials. For large carrier densities, the maximum gain can decrease with increasing carrier density. This behavior arises from a delicate balancing of state filling and dephasing, and implies the necessity of an accurate treatment of the carrier-density dependence of correlations. Measurements of the coherence properties of the light emitted from semiconductor quantum-dot lasers have raised considerable attention in recent years. We study the correlations between individual emission events on the basis of a microscopic semiconductor laser theory. This allows for a study of effects like Pauli blocking, modifications to the source term of spontaneous emission, and the absence of complete inversion, that strongly influence the emission characteristics of quantum dot based devices. A new and challenging material system for applications in the visible spectral range are nitride semiconductors. As crystal symmetry and bandmixing effects strongly influence the optical selection rules, the single

  11. Quantum Electrodynamics with Semiconductor Quantum Dots Coupled to Anderson‐localized Random Cavities

    DEFF Research Database (Denmark)

    Sapienza, Luca; Nielsen, Henri Thyrrestrup; Stobbe, Søren

    2011-01-01

    We demonstrate that the spontaneous emission decay rate of semiconductor quantum dots can be strongly modified by the coupling to disorder-induced Anderson-localized photonic modes. We experimentally measure, by means of time-resolved photoluminescence spectroscopy, the enhancement of the spontan...

  12. Microwave impedance imaging on semiconductor memory devices

    Science.gov (United States)

    Kundhikanjana, Worasom; Lai, Keji; Yang, Yongliang; Kelly, Michael; Shen, Zhi-Xun

    2011-03-01

    Microwave impedance microscopy (MIM) maps out the real and imaginary components of the tip-sample impedance, from which the local conductivity and dielectric constant distribution can be derived. The stray field contribution is minimized in our shielded cantilever design, enabling quantitative analysis of nano-materials and device structures. We demonstrate here that the MIM can spatially resolve the conductivity variation in a dynamic random access memory (DRAM) sample. With DC or low-frequency AC bias applied to the tip, contrast between n-doped and p-doped regions in the dC/dV images is observed, and p-n junctions are highlighted in the dR/dV images. The results can be directly compared with data taken by scanning capacitance microscope (SCM), which uses unshielded cantilevers and resonant electronics, and the MIM reveals more information of the local dopant concentration than SCM.

  13. A Novel Laser Technology for Nanostructure Formation in Elementary Semiconductors: Quantum Confinement Effect

    OpenAIRE

    Medvids, A; Onufrijevs, P; Dmitruk, M; Dmitruk, I; Pundyk, I

    2009-01-01

    Nowadays, nanostructures are one of the most investigated objects in solid-state physics, especially Quantum confinement effect in quantum dots, quantum wires and quantum wells. In the case of nanosize structures the energy band diagram of semiconductor has strongly changed. This leads to a crucial change of semiconductor properties such as: electrical (due to the change of free charge carrier concentration and electrons’ and holes’ mobility); optical (absorption coefficient, reflectivity in...

  14. Photoluminescence intermittency of semiconductor quantum dots in dielectric environments

    Energy Technology Data Exchange (ETDEWEB)

    Isaac, A.

    2006-08-11

    The experimental studies presented in this thesis deal with the photoluminescence intermittency of semiconductor quantum dots in different dielectric environments. Detailed analysis of intermittency statistics from single capped CdSe/ZnS, uncapped CdSe and water dispersed CdSe/ZnS QDs in different matrices provide experimental evidence for the model of photoionization with a charge ejected into the surrounding matrix as the source of PL intermittency phenomenon. We propose a self-trapping model to explain the increase of dark state lifetimes with the dielectric constant of the matrix. (orig.)

  15. Critical strain region evaluation of self-assembled semiconductor quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Sales, D L [Departamento de Ciencia de los Materiales e I. M. y Q. I., Universidad de Cadiz, Puerto Real, Cadiz (Spain); Pizarro, J [Departamento de Lenguajes y Sistemas Informaticos, Universidad de Cadiz, Puerto Real, Cadiz (Spain); Galindo, P L [Departamento de Lenguajes y Sistemas Informaticos, Universidad de Cadiz, Puerto Real, Cadiz (Spain); Garcia, R [Departamento de Ciencia de los Materiales e I. M. y Q. I., Universidad de Cadiz, Puerto Real, Cadiz (Spain); Trevisi, G [CNR-IMEM Institute, Parco delle Scienze 37a, 43100, Parma (Italy); Frigeri, P [CNR-IMEM Institute, Parco delle Scienze 37a, 43100, Parma (Italy); Nasi, L [CNR-IMEM Institute, Parco delle Scienze 37a, 43100, Parma (Italy); Franchi, S [CNR-IMEM Institute, Parco delle Scienze 37a, 43100, Parma (Italy); Molina, S I [Departamento de Ciencia de los Materiales e I. M. y Q. I., Universidad de Cadiz, Puerto Real, Cadiz (Spain)

    2007-11-28

    A novel peak finding method to map the strain from high resolution transmission electron micrographs, known as the Peak Pairs method, has been applied to In(Ga)As/AlGaAs quantum dot (QD) samples, which present stacking faults emerging from the QD edges. Moreover, strain distribution has been simulated by the finite element method applying the elastic theory on a 3D QD model. The agreement existing between determined and simulated strain values reveals that these techniques are consistent enough to qualitatively characterize the strain distribution of nanostructured materials. The correct application of both methods allows the localization of critical strain zones in semiconductor QDs, predicting the nucleation of defects, and being a very useful tool for the design of semiconductor devices.

  16. (DARPA) Topologically Protected Quantum Information Processing In Spin-Orbit Compled Semiconductors

    Science.gov (United States)

    2013-12-17

    tunneling peak experiments performed in our proposed semiconductor heterostructures in detail, explaining the absence of the gap closing signatures...true smoking-gun signature of MFs in spin-orbit coupled semiconductor nanowires in terms of a charge tunneling quantum interference experiment...5) Unambiguous determination of Majorana fermions: Charge tunneling interference in semiconductor nanowires : Using the fractionalization property

  17. Zinc Alloys for the Fabrication of Semiconductor Devices

    Science.gov (United States)

    Ryu, Yungryel; Lee, Tae S.

    2009-01-01

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

  18. Predictive Models for Semiconductor Device Design and Processing

    Science.gov (United States)

    Meyyappan, Meyya; Arnold, James O. (Technical Monitor)

    1998-01-01

    The device feature size continues to be on a downward trend with a simultaneous upward trend in wafer size to 300 mm. Predictive models are needed more than ever before for this reason. At NASA Ames, a Device and Process Modeling effort has been initiated recently with a view to address these issues. Our activities cover sub-micron device physics, process and equipment modeling, computational chemistry and material science. This talk would outline these efforts and emphasize the interaction among various components. The device physics component is largely based on integrating quantum effects into device simulators. We have two parallel efforts, one based on a quantum mechanics approach and the second, a semiclassical hydrodynamics approach with quantum correction terms. Under the first approach, three different quantum simulators are being developed and compared: a nonequlibrium Green's function (NEGF) approach, Wigner function approach, and a density matrix approach. In this talk, results using various codes will be presented. Our process modeling work focuses primarily on epitaxy and etching using first-principles models coupling reactor level and wafer level features. For the latter, we are using a novel approach based on Level Set theory. Sample results from this effort will also be presented.

  19. Artificially Structured Semiconductors to Model Novel Quantum Phenomena

    Energy Technology Data Exchange (ETDEWEB)

    Pinczuk, Aron [Columbia Univ., New York, NY (United States). Dept. of Applied Physics and Applied Mathematics; Wind, Shalom J. [Columbia Univ., New York, NY (United States). Dept. of Applied Physics and Applied Mathematics

    2018-01-13

    Award Period: September 1st, 2013 through February 15th, 2017 Submitted to the USDOE Office of Basic Energy Sciences By Aron Pinczuk and Shalom J. Wind Department of Applied Physics and Applied Mathematics Columbia University New York, NY 10027 January 2017 Award # DE-SC0010695 ABSTRACT Research in this project seeks to design, create and study a class of tunable artificial quantum structures in order to extend the range and scope of new and exciting physical phenomena and to explore the potential for new applications. Advanced nanofabrication was used to create an external potential landscape that acts as a lattice of confinement sites for electrons (and/or holes) in a two-dimensional electron gas in a high perfection semiconductor in such a manner that quantum interactions between different sites dictate the significant physics. Our current focus is on ‘artificial graphene’ (AG) in which a set of quantum dots (or sites) are patterned in a honeycomb lattice. The combination of leading edge nanofabrication with ultra-pure semiconductor materials in this project extends the frontier for small period, low-disorder AG systems, enabling the exploration of graphene physics in a semiconductor platform. TECHNICAL DESCRIPTION Contemporary condensed matter science has entered an era of discovery of new low-dimensional materials, such as graphene and other atomically thin materials, that exhibit exciting new physical phenomena that were previously inaccessible. Concurrent with the discovery and development of these new materials are impressive advancements in nanofabrication, which offer an ever-expanding toolbox for creating a myriad of high quality patterns at nanoscale dimensions. This project started about four years ago. Among its major achievements are the realizations of very small period artificial lattices with honeycomb topology in GaAs quantum wells. In our most recent work the periods of the ‘artificial graphene’ (AG) lattices extend down to 40 nm. These

  20. Quantum correlation control for two semiconductor microcavities connected by an optical fiber

    Science.gov (United States)

    Mohamed, A.-B. A.; Eleuch, H.

    2017-06-01

    We explore the quantum correlations for two coupled quantum wells. Each quantum well is inside a semiconductor microcavity. The two cavities are connected by an optical fiber. The study of quantum correlations, namely the geometric quantum discord, measurement-induced non-locality and negativity, reveals sudden death and sudden birth phenomena. These effects depend not only on the initial states, coupling strengths of the cavity-fiber and cavity-exciton constants, but also on the dissipation rates of the semiconductor microcavities. We show that the coupling constants control the quantum correlations.

  1. Quantum confinement in semiconductor nanofilms: Optical spectra and multiple exciton generation

    Science.gov (United States)

    Khmelinskii, Igor; Makarov, Vladimir I.

    2016-04-01

    We report optical absorption and photoluminescence (PL) spectra of Si and SnO2 nanocrystalline films in the UV-vis-NIR range, featuring discrete bands resulting from transverse quantum confinement, observed in the optical spectra of nanofilms for the first time ever. The film thickness ranged from 3.9 to 12.2 nm, depending on the material. The results are interpreted within the particle-in-a-box model, with infinite walls. The calculated values of the effective electron mass are independent on the film thickness and equal to 0.17mo (Si) and 0.21mo (SnO2), with mo the mass of the free electron. The second calculated model parameter, the quantum number n of the HOMO (valence band), was also thickness-independent: 8.00 (Si) and 7.00 (SnO2). The transitions observed in absorption all start at the level n and correspond to Δn = 1, 2, 3, …. The photoluminescence bands exhibit large Stokes shifts, shifting to higher energies with increased excitation energy. In effect, nanolayers of Si, an indirect-gap semiconductor, behave as a direct-gap semiconductor, as regards the transverse-quantized level system. A prototype Si-SnO2 nanofilm photovoltaic cell demonstrated photoelectron quantum yields achieving 2.5, showing clear evidence of multiple exciton generation, for the first time ever in a working nanofilm device.

  2. Dependence of the modulation response of quantum dot based nanocavity devices on the number of emitters

    DEFF Research Database (Denmark)

    Lorke, Michael; Nielsen, Torben Roland; Mørk, Jesper

    2011-01-01

    A microscopic theory is used to study the dynamical properties of semiconductor quantum dot based nanocavity laser systems. The carrier kinetics and photon populations are determined using a fully quantum mechanical treatment of the light‐matter coupling. In this work, we investigate the dependency...... of the modulation response in such devices on the number of emitters coupled to the cavity mode. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)...

  3. Diamond Quantum Devices in Biology.

    Science.gov (United States)

    Wu, Yuzhou; Jelezko, Fedor; Plenio, Martin B; Weil, Tanja

    2016-06-01

    The currently available techniques for molecular imaging capable of reaching atomic resolution are limited to low temperatures, vacuum conditions, or large amounts of sample. Quantum sensors based on the spin-dependent photoluminescence of nitrogen-vacancy (NV) centers in diamond offer great potential to achieve single-molecule detection with atomic resolution under ambient conditions. Diamond nanoparticles could also be prepared with implanted NV centers, thereby generating unique nanosensors that are able to traffic into living biological systems. Therefore, this technique might provide unprecedented access and insight into the structure and function of individual biomolecules under physiological conditions as well as observation of biological processes down to the quantum level with atomic resolution. The theory of diamond quantum sensors and the current developments from their preparation to sensing techniques have been critically discussed in this Minireview. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Quantum theory of spontaneous emission and coherent effects in semiconductor microstructures

    Science.gov (United States)

    Kira, M.; Jahnke, F.; Hoyer, W.; Koch, S. W.

    1999-11-01

    A fully quantum-mechanical theory for the interaction of light and electron-hole excitations in semiconductor quantum-well systems is developed. The resulting many-body hierarchy for the correlation functions is truncated using a dynamical decoupling scheme leading to coupled semiconductor luminescence and Bloch equations. For incoherent excitation conditions, the theory is used to describe nonlinear excitonic emission properties of single-quantum wells, optically coupled multiple quantum-well systems, and quantum wells in a microcavity. Resonant coherent optical excitation leads to a direct coupling between the induced coherent polarization and photoluminescence. The resulting quantum corrections to the semiclassical semiconductor Bloch equations and the coherent contributions to the semiconductor luminescence equations are discussed. The secondary emission in directions deviating from the coherent excitation direction after femtosecond-pulse excitation is studied. Coherent control and quadrature squeezing for the light emission are analyzed.

  5. Optimal control and quantum simulations in superconducting quantum devices

    Energy Technology Data Exchange (ETDEWEB)

    Egger, Daniel J.

    2014-10-31

    Quantum optimal control theory is the science of steering quantum systems. In this thesis we show how to overcome the obstacles in implementing optimal control for superconducting quantum bits, a promising candidate for the creation of a quantum computer. Building such a device will require the tools of optimal control. We develop pulse shapes to solve a frequency crowding problem and create controlled-Z gates. A methodology is developed for the optimisation towards a target non-unitary process. We show how to tune-up control pulses for a generic quantum system in an automated way using a combination of open- and closed-loop optimal control. This will help scaling of quantum technologies since algorithms can calibrate control pulses far more efficiently than humans. Additionally we show how circuit QED can be brought to the novel regime of multi-mode ultrastrong coupling using a left-handed transmission line coupled to a right-handed one. We then propose to use this system as an analogue quantum simulator for the Spin-Boson model to show how dissipation arises in quantum systems.

  6. Theory of semiconductor junction devices a textbook for electrical and electronic engineers

    CERN Document Server

    Leck, J H

    1967-01-01

    Theory of Semiconductor Junction Devices: A Textbook for Electrical and Electronic Engineers presents the simplified numerical computation of the fundamental electrical equations, specifically Poisson's and the Hall effect equations. This book provides the fundamental theory relevant for the understanding of semiconductor device theory. Comprised of 10 chapters, this book starts with an overview of the application of band theory to the special case of semiconductors, both intrinsic and extrinsic. This text then describes the electrical properties of conductivity, semiconductors, and Hall effe

  7. Irradiation damages of semiconductor devices and their improvement

    Energy Technology Data Exchange (ETDEWEB)

    Uwatoko, Yoshiya [Saitama Univ., Urawa (Japan); Ohyama, Hidenori; Hayama, Kiyoteru; Hakata, Tetsuya; Kudou, Tomohiro

    1998-01-01

    In this study, effect of radiation on semiconductor devices was evaluated at both sides of electrical and crystalline properties for two years from 1995 fiscal years. And, damage of Si(sub 1-x)Ge(sub x) device was considered at viewpoints of Ge content and sprung-out atomic number and non ionization energy loss of constituting atom formed by radiation on its radiation source dependency of damage. This paper was a report on proton beam damage of the Si(sub 1-x)Ge(sub x) device, neutron damage of InGaAs photodiode, and effect of Ga content and kinds of beam on their damages. (G.K.)

  8. Semiconductor Modeling Techniques

    CERN Document Server

    Xavier, Marie

    2012-01-01

    This book describes the key theoretical techniques for semiconductor research to quantitatively calculate and simulate the properties. It presents particular techniques to study novel semiconductor materials, such as 2D heterostructures, quantum wires, quantum dots and nitrogen containing III-V alloys. The book is aimed primarily at newcomers working in the field of semiconductor physics to give guidance in theory and experiment. The theoretical techniques for electronic and optoelectronic devices are explained in detail.

  9. Light-matter Interactions in Semiconductors and Metals: From Nitride Optoelectronics to Quantum Plasmonics

    Science.gov (United States)

    Narang, Prineha

    This thesis puts forth a theory-directed approach coupled with spectroscopy aimed at the discovery and understanding of light-matter interactions in semiconductors and metals. The first part of the thesis presents the discovery and development of Zn-IV nitride materials. The commercial prominence in the optoelectronics industry of tunable semiconductor alloy materials based on nitride semiconductor devices, specifically InGaN, motivates the search for earth-abundant alternatives for use in efficient, high-quality optoelectronic devices. II-IV-N2 compounds, which are closely related to the wurtzite-structured III-N semiconductors, have similar electronic and optical properties to InGaN namely direct band gaps, high quantum efficiencies and large optical absorption coefficients. The choice of different group II and group IV elements provides chemical diversity that can be exploited to tune the structural and electronic properties through the series of alloys. The first theoretical and experimental investigation of the ZnSnxGe1--xN2 series as a replacement for III-nitrides is discussed here. The second half of the thesis shows ab-initio calculations for surface plasmons and plasmonic hot carrier dynamics. Surface plasmons, electromagnetic modes confined to the surface of a conductor-dielectric interface, have sparked renewed interest because of their quantum nature and their broad range of applications. The decay of surface plasmons is usually a detriment in the field of plasmonics, but the possibility to capture the energy normally lost to heat would open new opportunities in photon sensors, energy conversion devices and switching. A theoretical understanding of plasmon-driven hot carrier generation and relaxation dynamics in the ultrafast regime is presented here. Additionally calculations for plasmon-mediated upconversion as well as an energy-dependent transport model for these non-equilibrium carriers are shown. Finally, this thesis gives an outlook on the

  10. Irradiation damage of SiC semiconductor device (I)

    International Nuclear Information System (INIS)

    Park, Ji Yeon; Kim, Weon Ju

    2000-09-01

    This report reviewed the irradiation damage of SiC semiconductor devices and examined a irradiation behavior of SiC single crystal as a pre-examination for evaluation of irradiation behavior of SiC semiconductor devices. The SiC single was crystal irradiated by gamma-beam, N+ ion and electron beam. Annealing examinations of the irradiated specimens also were performed at 500 deg C. N-type 6H-SiC dopped with N+ ion was used and irradiation doses of gamma-beam, N+ion and electron beam were up to 200 Mrad, 1x10 16 N + ions/cm 2 and 3.6 x 10 17 e/cm 2 and 1.08 x 10 18 e/cm 2 , respectively. Irradiation damages were analyzed by the EPR method. Additionally, properties of SiC, information about commercial SiC single crystals and the list of web sites with related to the SiC device were described in the appendix

  11. Irradiation damage of SiC semiconductor device (I)

    Energy Technology Data Exchange (ETDEWEB)

    Park, Ji Yeon; Kim, Weon Ju

    2000-09-01

    This report reviewed the irradiation damage of SiC semiconductor devices and examined a irradiation behavior of SiC single crystal as a pre-examination for evaluation of irradiation behavior of SiC semiconductor devices. The SiC single was crystal irradiated by gamma-beam, N+ ion and electron beam. Annealing examinations of the irradiated specimens also were performed at 500 deg C. N-type 6H-SiC dopped with N+ ion was used and irradiation doses of gamma-beam, N+ion and electron beam were up to 200 Mrad, 1x10{sup 16} N{sup +} ions/cm{sup 2} and 3.6 x 10{sup 17} e/cm{sup 2} and 1.08 x 10{sup 18} e/cm{sup 2} , respectively. Irradiation damages were analyzed by the EPR method. Additionally, properties of SiC, information about commercial SiC single crystals and the list of web sites with related to the SiC device were described in the appendix.

  12. Efficient calculation of dissipative quantum transport properties in semiconductor nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Greck, Peter

    2012-11-26

    We present a novel quantum transport method that follows the non-equilibrium Green's function (NEGF) framework but side steps any self-consistent calculation of lesser self-energies by replacing them by a quasi-equilibrium expression. We termed this method the multi-scattering Buettiker-Probe (MSB) method. It generalizes the so-called Buettiker-Probe model but takes into account all relevant individual scattering mechanisms. It is orders of magnitude more efficient than a fully selfconsistent non-equilibrium Green's function calculation for realistic devices, yet accurately reproduces the results of the latter method as well as experimental data. This method is fairly easy to implement and opens the path towards realistic three-dimensional quantum transport calculations. In this work, we review the fundamentals of the non-equilibrium Green's function formalism for quantum transport calculations. Then, we introduce our novel MSB method after briefly reviewing the original Buettiker-Probe model. Finally, we compare the results of the MSB method to NEGF calculations as well as to experimental data. In particular, we calculate quantum transport properties of quantum cascade lasers in the terahertz (THz) and the mid-infrared (MIR) spectral domain. With a device optimization algorithm based upon the MSB method, we propose a novel THz quantum cascade laser design. It uses a two-well period with alternating barrier heights and complete carrier thermalization for the majority of the carriers within each period. We predict THz laser operation for temperatures up to 250 K implying a new temperature record.

  13. Fundamental properties of devices for quantum information technology

    DEFF Research Database (Denmark)

    Nielsen, Per Kær

    This thesis reports a theoretical investigation of the influence of the electronphonon interaction on semiconductor cavity quantum electrodynamical systems, specifically a quantum dot coupled to an optical microcavity. We develop a theoretical description of the decay dynamics of the quantum dot ...

  14. Optical control of the spin of a magnetic atom in a semiconductor quantum dot

    Directory of Open Access Journals (Sweden)

    Besombes L.

    2015-04-01

    Full Text Available The control of single spins in solids is a key but challenging step for any spin-based solid-state quantumcomputing device. Thanks to their expected long coherence time, localized spins on magnetic atoms in a semiconductor host could be an interesting media to store quantum information in the solid state. Optical probing and control of the spin of individual or pairs of Manganese (Mn atoms (S = 5/2 have been obtained in II-VI and IIIV semiconductor quantum dots during the last years. In this paper, we review recently developed optical control experiments of the spin of an individual Mn atoms in II-VI semiconductor self-assembled or strain-free quantum dots (QDs.We first show that the fine structure of the Mn atom and especially a strained induced magnetic anisotropy is the main parameter controlling the spin memory of the magnetic atom at zero magnetic field. We then demonstrate that the energy of any spin state of a Mn atom or pairs of Mn atom can be independently tuned by using the optical Stark effect induced by a resonant laser field. The strong coupling with the resonant laser field modifies the Mn fine structure and consequently its dynamics.We then describe the spin dynamics of a Mn atom under this strong resonant optical excitation. In addition to standard optical pumping expected for a resonant excitation, we show that the Mn spin population can be trapped in the state which is resonantly excited. This effect is modeled considering the coherent spin dynamics of the coupled electronic and nuclear spin of the Mn atom optically dressed by a resonant laser field. Finally, we discuss the spin dynamics of a Mn atom in strain-free QDs and show that these structures should permit a fast optical coherent control of an individual Mn spin.

  15. Quantum effects in ion implanted devices

    International Nuclear Information System (INIS)

    Jamieson, D.N.; Chan, V.; Hudson, F.E.; Andresen, S.E.; Yang, C.; Hopf, T.; Hearne, S.M.; Pakes, C.I.; Prawer, S.; Gauja, E.; Yang, C.; Dzurak, A.S.; Yang, C.; Clark, R.G.; Yang, C.

    2005-01-01

    Fabrication of nanoscale devices that exploit the rules of quantum mechanics to process information presents formidable technical challenges because it will be necessary to control quantum states at the level of individual atoms, electrons or photons. We have developed a pathway to the construction of quantum devices using ion implantation and demonstrate, using charge transport analysis, that the devices exhibit single electron effects. We construct devices that employ two P donors in Si by employing the technique of ion beam induced charge (IBIC) in which single 14 keV P ions can be implanted into ultra-pure silicon by monitoring on-substrate detector electrodes. We have used IBIC with a MeV nuclear microprobe to map and measure the charge collection efficiency in the development of the electrode structure and show that 100% charge collection efficiency can be achieved leading to the fabrication of prototype devices that display quantum effects in the transport of single charge quanta between the islands of implanted donors. (author). 9 refs., 4 figs., 1 tab

  16. Quantum effects in ion implanted devices

    International Nuclear Information System (INIS)

    Jamieson, D.N.; Chan, V.; Hudson, F.E.; Andresen, S.E.; Yang, C.; Hopf, T.; Hearne, S.M.; Pakes, C.I.; Prawer, S.; Gauja, E.; Dzurak, A.S.; Clark, R.G.

    2006-01-01

    Fabrication of nanoscale devices that exploit the rules of quantum mechanics to process information presents formidable technical challenges because of the need to control quantum states at the level of individual atoms, electrons or photons. We have used ion implantation to fabricate devices on the scale of 10 nm that have allowed the development and test of nanocircuitry for the control of charge transport at the level of single electrons. This fabrication method is compatible with the construction of devices that employ counted P dopants in Si by employing the technique of ion beam induced charge (IBIC) in which single 14 keV P ions can be implanted into ultra-pure silicon substrates by monitoring on-substrate detector electrodes. We have used IBIC with a MeV nuclear microprobe to map and measure the charge collection efficiency in the development of the electrode structure and show that 100% charge collection efficiency can be achieved. Prototype devices fabricated by this method have been used to investigate quantum effects in the control and transport of single electrons with potential applications to solid state quantum information processing devices

  17. Development of segmented semiconductor arrays for quantum imaging

    CERN Document Server

    Mikulec, Bettina

    2003-01-01

    The field of pixel detectors has grown strongly in recent years through progress in CMOS technology, which permits many hundreds of transistors to be implemented in an area of 50-200 um2. Pulse processing electronics with noise of the order of 100 e- RMS permits to distinguish photons of a few keV from background noise. Techniques are under development, which should allow single chip systems (area ~1 cm2) to be extended to larger areas. This paper gives an introduction into the concept of quantum imaging using direct conversion in segmented semiconductor arrays. An overview of projects from this domain using strip, pad and in particular hybrid pixel detectors will be presented. One of these projects, the Medipix project, is described in more detail. The effect of different correction methods like threshold adjustment and flat field correction is illustrated and new measurement results and images presented.

  18. Neutron radiation effects on metal oxide semiconductor (MOS) devices

    Energy Technology Data Exchange (ETDEWEB)

    Abdul Amir, Haider F. [School of Science and Technology, University Malaysia Sabah, 88999 Kota Kinabalu, Sabah (Malaysia)], E-mail: haider@ums.edu.my; Chik, Abdulah [School of Science and Technology, University Malaysia Sabah, 88999 Kota Kinabalu, Sabah (Malaysia)

    2009-09-15

    The main purpose of this study is to provide the knowledge and data on Deuterium-Tritium (D-T) fusion neutron induced damage in MOS devices. Silicon metal oxide semiconductor (MOS) devices are currently the cornerstone of the modern microelectronics industry. However, when a MOS device is exposed to a flux of energetic radiation or particles, the resulting effects from this radiation can cause several degradation of the device performance and of its operating life. The part of MOS structure (metal oxide semiconductor) most sensitive to neutron radiation is the oxide insulating layer (SiO{sub 2}). When ionizing radiation passes through the oxide, the energy deposited creates electron-hole pairs. These electron-hole pairs have been seriously hazardous to the performance of these electronic components. The degradation of the current gain of the dual n-channel depletion mode MOS caused by neutron displacement defects, was measured using in situ method during neutron irradiation. The average degradation of the gain of the current is about 35 mA, and the change in channel current gain increased proportionally with neutron fluence. The total fusion neutron displacement damage was found to be 4.8 x 10{sup -21} dpa per n/cm{sup 2}, while the average fraction of damage in the crystal of silicon was found to be 1.24 x 10{sup -12}. All the MOS devices tested were found to be controllable after neutron irradiation and no permanent damage was caused by neutron fluence irradiation below 10{sup 10}n/cm{sup 2}. The calculation results shows that (n,{alpha}) reaction induced soft-error cross-section about 8.7 x 10{sup -14} cm{sup 2}, and for recoil atoms about 2.9 x 10{sup -15} cm{sup 2}, respectively.

  19. Neutron radiation effects on metal oxide semiconductor (MOS) devices

    International Nuclear Information System (INIS)

    Abdul Amir, Haider F.; Chik, Abdulah

    2009-01-01

    The main purpose of this study is to provide the knowledge and data on Deuterium-Tritium (D-T) fusion neutron induced damage in MOS devices. Silicon metal oxide semiconductor (MOS) devices are currently the cornerstone of the modern microelectronics industry. However, when a MOS device is exposed to a flux of energetic radiation or particles, the resulting effects from this radiation can cause several degradation of the device performance and of its operating life. The part of MOS structure (metal oxide semiconductor) most sensitive to neutron radiation is the oxide insulating layer (SiO 2 ). When ionizing radiation passes through the oxide, the energy deposited creates electron-hole pairs. These electron-hole pairs have been seriously hazardous to the performance of these electronic components. The degradation of the current gain of the dual n-channel depletion mode MOS caused by neutron displacement defects, was measured using in situ method during neutron irradiation. The average degradation of the gain of the current is about 35 mA, and the change in channel current gain increased proportionally with neutron fluence. The total fusion neutron displacement damage was found to be 4.8 x 10 -21 dpa per n/cm 2 , while the average fraction of damage in the crystal of silicon was found to be 1.24 x 10 -12 . All the MOS devices tested were found to be controllable after neutron irradiation and no permanent damage was caused by neutron fluence irradiation below 10 10 n/cm 2 . The calculation results shows that (n,α) reaction induced soft-error cross-section about 8.7 x 10 -14 cm 2 , and for recoil atoms about 2.9 x 10 -15 cm 2 , respectively.

  20. Computer-automated tuning of semiconductor double quantum dots into the single-electron regime

    NARCIS (Netherlands)

    Baart, T.A.; Eendebak, P.T.; Reichl, C.; Wegscheider, W.; Vandersypen, L.M.K.

    2016-01-01

    We report the computer-automated tuning of gate-defined semiconductor double quantum dots in GaAs heterostructures. We benchmark the algorithm by creating three double quantum dots inside a linear array of four quantum dots. The algorithm sets the correct gate voltages for all the gates to tune the

  1. Nonvolatile and Cryogenic-Compatible Quantum Memory Devices (QuMEM)

    Science.gov (United States)

    2016-06-01

    11 3.1 COMPLIMENTARY METAL-OXIDE- SEMICONDUCTOR (CMOS)......................... 11 3.2 RAPID- SINGLE -FLUX QUANTUM (RSFQ...in the plasma treatment . Section 6 explains the electrical characterization of these devices. 41 Table 5. Al/AlOx/Al device process flow. Step ...collection and storage of all data each clock cycle (generated by a single gigahertz ADC) approaches petabyte scale each day

  2. Modeling and simulation of bulk gallium nitride power semiconductor devices

    Directory of Open Access Journals (Sweden)

    G. Sabui

    2016-05-01

    Full Text Available Bulk gallium nitride (GaN power semiconductor devices are gaining significant interest in recent years, creating the need for technology computer aided design (TCAD simulation to accurately model and optimize these devices. This paper comprehensively reviews and compares different GaN physical models and model parameters in the literature, and discusses the appropriate selection of these models and parameters for TCAD simulation. 2-D drift-diffusion semi-classical simulation is carried out for 2.6 kV and 3.7 kV bulk GaN vertical PN diodes. The simulated forward current-voltage and reverse breakdown characteristics are in good agreement with the measurement data even over a wide temperature range.

  3. Modeling and simulation of bulk gallium nitride power semiconductor devices

    Science.gov (United States)

    Sabui, G.; Parbrook, P. J.; Arredondo-Arechavala, M.; Shen, Z. J.

    2016-05-01

    Bulk gallium nitride (GaN) power semiconductor devices are gaining significant interest in recent years, creating the need for technology computer aided design (TCAD) simulation to accurately model and optimize these devices. This paper comprehensively reviews and compares different GaN physical models and model parameters in the literature, and discusses the appropriate selection of these models and parameters for TCAD simulation. 2-D drift-diffusion semi-classical simulation is carried out for 2.6 kV and 3.7 kV bulk GaN vertical PN diodes. The simulated forward current-voltage and reverse breakdown characteristics are in good agreement with the measurement data even over a wide temperature range.

  4. Theory of photovoltaic characteristics of semiconductor quantum dot solar cells

    International Nuclear Information System (INIS)

    Wu, Yuchang; Asryan, Levon V.

    2016-01-01

    We develop a comprehensive rate equations model for semiconductor quantum dot solar cells (QDSCs). The model is based on the continuity equations with a proper account for quantum dots (QDs). A general analytical expression for the total current density is obtained, and the current-voltage characteristic is studied for several specific situations. The degradation in the open circuit voltage of the QDSC is shown to be due to strong spontaneous radiative recombination in QDs. Due to small absorption coefficient of the QD ensemble, the improvement in the short circuit current density is negligible if only one QD layer is used. If spontaneous radiative recombination would be suppressed in QDs, a QDSC with multiple QD layers would have significantly higher short circuit current density and power conversion efficiency than its conventional counterpart. The effects of photoexcitation of carriers from discrete-energy states in QDs to continuum-energy states are discussed. An extended model, which includes excited states in QDs, is also introduced.

  5. Optical Design of Dilute Nitride Quantum Wells Vertical Cavity Semiconductor Optical Amplifiers for Communication Systems

    Directory of Open Access Journals (Sweden)

    Faten A. Chaqmaqchee

    2016-04-01

    Full Text Available III-V semiconductors components such as Gallium Arsenic (GaAs, Indium Antimony (InSb, Aluminum Arsenic (AlAs and Indium Arsenic (InAs have high carrier mobilities and direct energy gaps. This is making them indispensable for today’s optoelectronic devices such as semiconductor lasers and optical amplifiers at 1.3 μm wavelength operation. In fact, these elements are led to the invention of the Gallium Indium Nitride Arsenic (GaInNAs, where the lattice is matched to GaAs for such applications. This article is aimed to design dilute nitride GaInNAs quantum wells (QWs enclosed between top and bottom of Aluminum (Gallium Arsenic Al(GaAs distributed bragg mirrors (DBRs using MATLAB® program. Vertical cavity semiconductor optical amplifiers (VCSOAs structures are based on Fabry Perot (FP method to design optical gain and bandwidth gain to be operated in reflection and transmission modes. The optical model gives access to the contact layer of epitaxial structure and the reflectivity for successive radiative modes, their lasing thresholds, emission wavelengths and optical field distributions in the laser cavity.

  6. Magnetoexcitons in type-II semiconductor quantum dots

    Science.gov (United States)

    Fuster, Gonzalo; Barticevic, Zdenka; Pacheco, Monica; Oliveira, Luiz E.

    2004-03-01

    We present a theoretical investigation of excitons in type-II semiconductor quantum dots (QD). In these systems the confinement of electrons inside the QD and the hole outside the QD produces a ring-like structure [1-2]. Recently, Ribeiro et al [3], in a magnetophotoluminescence study of type-II InP/GaAs self-assembled quantum dots, observed Aharonov-Bohm-type oscillations characteristic of the ring topology for neutral excitons. Using a simple model they have derived the groundstate hole energy as a function of the magnetic field, and obtained values for the ring parameters which are in good agreement with the measured values. However, some of the features observed experimentally, in the photoluminescence intensity, can not be well explained under that approach. In this work we present a more realistic model which considers the finite width of the ring and the electron-hole interaction included via a perturbative approach. The calculations are performed within the oneparticle formalism using the effective mass approximation. The confinement potential for electrons is modelled as the superposition of a quantum well potential along the axial direction, and a parabolic lateral confinement potential. The energies for the hole in the ring plane are calculated using the method of reference [4]. Theoretical calculations are in good agreement with the experimental results of reference [3] provided that excitonic effects are properly taken into account. References 1. A.O. Govorov et al., Physica E 13 , 297 (2002). 2. K. L. Janssens et al. Phys. Rev B64, 155324 (2001), and Phys. Rev. B66, 075314 (2002). 3. E. Ribeiro, G. Medeiros-Ribeiro, and W.Carvalho Jr., and A.O. Govorov, condmat/0304092 (2003). 4. Z. Barticevic, G. Fuster, and M. Pacheco,Phys. Rev. B 65, 193307 (2002).

  7. Measurement device-independent quantum dialogue

    Science.gov (United States)

    Maitra, Arpita

    2017-12-01

    Very recently, the experimental demonstration of quantum secure direct communication (QSDC) with state-of-the-art atomic quantum memory has been reported (Zhang et al. in Phys Rev Lett 118:220501, 2017). Quantum dialogue (QD) falls under QSDC where the secrete messages are communicated simultaneously between two legitimate parties. The successful experimental demonstration of QSDC opens up the possibilities for practical implementation of QD protocols. Thus, it is necessary to analyze the practical security issues of QD protocols for future implementation. Since the very first proposal for QD by Nguyen (Phys Lett A 328:6-10, 2004), a large number of variants and extensions have been presented till date. However, all of those leak half of the secret bits to the adversary through classical communications of the measurement results. In this direction, motivated by the idea of Lo et al. (Phys Rev Lett 108:130503, 2012), we propose a measurement device-independent quantum dialogue scheme which is resistant to such information leakage as well as side-channel attacks. In the proposed protocol, Alice and Bob, two legitimate parties, are allowed to prepare the states only. The states are measured by an untrusted third party who may himself behave as an adversary. We show that our protocol is secure under this adversarial model. The current protocol does not require any quantum memory, and thus, it is inherently robust against memory attacks. Such robustness might not be guaranteed in the QSDC protocol with quantum memory (Zhang et al. 2017).

  8. Nanosecond-timescale spin transfer using individual electrons in a quadruple-quantum-dot device

    Energy Technology Data Exchange (ETDEWEB)

    Baart, T. A.; Jovanovic, N.; Vandersypen, L. M. K. [QuTech and Kavli Institute of Nanoscience, Delft University of Technology, P.O. Box 5046, 2600 GA Delft (Netherlands); Reichl, C.; Wegscheider, W. [Solid State Physics Laboratory, ETH Zürich, 8093 Zürich (Switzerland)

    2016-07-25

    The ability to coherently transport electron-spin states between different sites of gate-defined semiconductor quantum dots is an essential ingredient for a quantum-dot-based quantum computer. Previous shuttles using electrostatic gating were too slow to move an electron within the spin dephasing time across an array. Here, we report a nanosecond-timescale spin transfer of individual electrons across a quadruple-quantum-dot device. Utilizing enhanced relaxation rates at a so-called hot spot, we can upper bound the shuttle time to at most 150 ns. While actual shuttle times are likely shorter, 150 ns is already fast enough to preserve spin coherence in, e.g., silicon based quantum dots. This work therefore realizes an important prerequisite for coherent spin transfer in quantum dot arrays.

  9. Instantaneous amplitude and frequency dynamics of coherent wave mixing in semiconductor quantum wells

    International Nuclear Information System (INIS)

    Chemla, D.S.

    1993-01-01

    This article reviews recent investigations of nonlinear optical processes in semiconductors. Section II discusses theory of coherent wave mixing in semiconductors, with emphasis on resonant excitation with only one exciton state. Section III reviews recent experimental investigations of amplitude and phase of coherent wave-mixing resonant with quasi-2d excitons in GaAs quantum wells

  10. Quantum dynamical phenomena of independent electrons in semiconductor superlattices subject to a uniform electric field

    International Nuclear Information System (INIS)

    Bouchard, A.M.

    1994-01-01

    This report discusses the following topics: Bloch oscillations and other dynamical phenomena of electrons in semiconductor superlattices; solvable dynamical model of an electron in a one-dimensional aperiodic lattice subject to a uniform electric field; and quantum dynamical phenomena of electrons in aperiodic semiconductor superlattices

  11. Semiconductor Devices Inspired By and Integrated With Biology

    Energy Technology Data Exchange (ETDEWEB)

    Rogers, John [University of Illinois

    2012-04-25

    Biology is curved, soft and elastic; silicon wafers are not. Semiconductor technologies that can bridge this gap in form and mechanics will create new opportunities in devices that adopt biologically inspired designs or require intimate integration with the human body. This talk describes the development of ideas for electronics that offer the performance of state-of-the-art, wafer- based systems but with the mechanical properties of a rubber band. We explain the underlying materials science and mechanics of these approaches, and illustrate their use in (1) bio- integrated, ‘tissue-like’ electronics with unique capabilities for mapping cardiac and neural electrophysiology, and (2) bio-inspired, ‘eyeball’ cameras with exceptional imaging properties enabled by curvilinear, Petzval designs.

  12. System for characterizing semiconductor materials and photovoltaic devices through calibration

    Science.gov (United States)

    Sopori, B.L.; Allen, L.C.; Marshall, C.; Murphy, R.C.; Marshall, T.

    1998-05-26

    A method and apparatus are disclosed for measuring characteristics of a piece of material, typically semiconductor materials including photovoltaic devices. The characteristics may include dislocation defect density, grain boundaries, reflectance, external LBIC, internal LBIC, and minority carrier diffusion length. The apparatus includes a light source, an integrating sphere, and a detector communicating with a computer. The measurement or calculation of the characteristics is calibrated to provide accurate, absolute values. The calibration is performed by substituting a standard sample for the piece of material, the sample having a known quantity of one or more of the relevant characteristics. The quantity measured by the system of the relevant characteristic is compared to the known quantity and a calibration constant is created thereby. 44 figs.

  13. Optical dynamics in low-dimensional semiconductor heterostructures. Quantum dots and quantum cascade lasers

    Energy Technology Data Exchange (ETDEWEB)

    Weber, Carsten

    2008-07-01

    This work is focused on the optical dynamics of mesoscopic semiconductor heterostructures, using as prototypes zero-dimensional quantum dots and quantum cascade lasers which consist of quasitwo- dimensional quantum wells. Within a density matrix theory, a microscopic many-particle theory is applied to study scattering effects in these structures: the coupling to external as well as local fields, electron-phonon coupling, coupling to impurities, and Coulomb coupling. For both systems, the investigated effects are compared to experimentally observed results obtained during the past years. In quantum dots, the three-dimensional spatial confinement leads to the necessity to consider a quantum kinetic description of the dynamics, resulting in non-Markovian electron-phonon effects. This can be seen in the spectral phonon sidebands due to interaction with acoustic phonons as well as a damping of nonlinear Rabi oscillations which shows a nonmonotonous intensity and pulse duration dependence. An analysis of the inclusion of the self-interaction of the quantum dot shows that no dynamical local field terms appear for the simple two-level model. Considering local fields which have their origin in many quantum dots, consequences for a two-level quantum dot such as a zero-phonon line broadening and an increasing signal in photon echo experiments are found. For the use of quantum dots in an optical spin control scheme, it is found that the dephasing due to the electron-phonon interaction can be dominant in certain regimes. Furthermore, soliton and breather solutions are studied analytically in nonlinear quantum dot ensembles. Generalizing to quasi-two-dimensional structures, the intersubband dynamics of quantum cascade laser structures is investigated. A dynamical theory is considered in which the temporal evolution of the subband populations and the current density as well as the influence of scattering effects is studied. In the nonlinear regime, the scattering dependence and

  14. Application of copper-carbon fiber composites to power semiconductor devices

    Science.gov (United States)

    Kuniya, Keiichi; Arakawa, Hideo; Sakaue, Tadashi; Minorikawa, Hitoshi; Akeyama, Kenji; Sakamoto, Tatsuji

    1988-01-01

    Copper-carbon composite electrodes are used in a series of power semiconductor devices, i.e., resin molded diodes, button-type diodes, stud-type diodes, power modules, and integrated circuit igniter modules. The properties of these power semiconductor devices compare favorably with those conventional devices using Mo or W electrodes. In thermal fatigue tests, no degradation in the electrical and mechanical characteristics of these devices are observed. The new composite electrode with carbon fibers satisfies all of the major requirements for the electrodes in power semiconductor devices.

  15. Python Scripts for Automation of Current-Voltage Testing of Semiconductor Devices (FY17)

    Science.gov (United States)

    2017-01-01

    ARL-TR-7923 ● JAN 2017 US Army Research Laboratory Python Scripts for Automation of Current- Voltage Testing of Semiconductor ...Laboratory Python Scripts for Automation of Current- Voltage Testing of Semiconductor Devices (FY17) by Bryan H Zhao Oak Ridge Institute for Science...Testing of Semiconductor Devices (FY17) 5a. CONTRACT NUMBER 1120-1120-99 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) Bryan H Zhao

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

    Science.gov (United States)

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

    2017-06-01

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

  17. Fabrication of a graphene quantum dot device

    Science.gov (United States)

    Lee, Jeong Il; Kim, Eunseong

    2014-03-01

    Graphene, which exhibits a massless Dirac-like spectrum for its electrons, has shown impressive properties for nano-electronics applications including a high mobility and a width dependent bandgap. We will report the preliminary report on the transport property of the suspended graphene nano-ribbon(GNR) quantum dot device down to dilution refrigerator temperature. This GNR QD device was fabricated to realize an ideal probe to investigate Kondo physics--a characteristic phenomenon in the physics of strongly correlated electrons. We gratefully acknowledge the financial support by the National Research Foundation of Korea through the Creative Research Initiatives.

  18. Femtosecond spectroscopy in semiconductors: a key to coherences, correlations and quantum kinetics

    International Nuclear Information System (INIS)

    Axt, V M; Kuhn, T

    2004-01-01

    The application of femtosecond spectroscopy to the study of ultrafast dynamics in semiconductor materials and nanostructures is reviewed with particular emphasis on the physics that can be learned from it. Excitation with ultrashort optical pulses in general results in the creation of coherent superpositions and correlated many-particle states. The review comprises a discussion of the dynamics of this correlated many-body system during and after pulsed excitation as well as its analysis by means of refined measurements and advanced theories. After an introduction of basic concepts-such as coherence, correlation and quantum kinetics-a brief overview of the most important experimental techniques and theoretical approaches is given. The remainder of this paper is devoted to specific results selected in order to highlight how femtosecond spectroscopy gives access to the physics of coherences, correlations and quantum kinetics involving charge, spin and lattice degrees of freedom. First examples deal with the dynamics of basic laser-induced coherences that can be observed, e.g. in quantum beat spectroscopy, in coherent control measurements or in experiments using few-cycle pulses. The phenomena discussed here are basic in the sense that they can be understood to a large extent on the mean-field level of the theory. Nevertheless, already on this level it is found that semiconductors behave substantially differently from atomic systems. Subsequent sections report on the occurrence of coherences and correlations beyond the mean-field level that are mediated either by carrier-phonon or carrier-carrier interactions. The corresponding analysis gives deep insight into fundamental issues such as the energy-time uncertainty, pure dephasing in quantum dot structures, the role of two-pair or even higher correlations and the build-up of screening. Finally results are presented concerning the ultrafast dynamics of resonantly coupled excitations, where a combination of different

  19. Towards quantum optics and entanglement with electron spin ensembles in semiconductors

    NARCIS (Netherlands)

    van der Wal, Caspar H.; Sladkov, Maksym

    We discuss a technique and a material system that enable the controlled realization of quantum entanglement between spin-wave modes of electron ensembles in two spatially separated pieces of semiconductor material. The approach uses electron ensembles in GaAs quantum wells that are located inside

  20. Recent progress in InAs/InP quantum dash nanostructures and devices

    KAUST Repository

    Ooi, Boon S.

    2016-03-24

    In this talk, we will give an outline and introduction to the broad inter-band emission devices focusing on the InAs/InP quantum dash material system, device physics and establishment of ultrabroad stimulated emission behavior. In addition, technologies for growing these nanostructures as well as engineer the bandgap of quantum dash based system using epitaxy growth techniques and postgrowth intermixing methods will be presented. At device level, we will focus our discussion on our recent progress in extending the ultra-broad lasing emission from quantum dash lasers, and achievements in broad gain semiconductor optical amplifiers (SOA), mode locked lasers, comb-lasers, wide band superluminsect diodes fabricated on this material system. © 2015 IEEE.

  1. Readout of the atomtronic quantum interference device

    Science.gov (United States)

    Haug, Tobias; Tan, Joel; Theng, Mark; Dumke, Rainer; Kwek, Leong-Chuan; Amico, Luigi

    2018-01-01

    A Bose-Einstein condensate confined in ring shaped lattices interrupted by a weak link and pierced by an effective magnetic flux defines the atomic counterpart of the superconducting quantum interference device: the atomtronic quantum interference device (AQUID). In this paper, we report on the detection of current states in the system through a self-heterodyne protocol. Following the original proposal of the NIST and Paris groups, the ring-condensate many-body wave function interferes with a reference condensate expanding from the center of the ring. We focus on the rf AQUID which realizes effective qubit dynamics. Both the Bose-Hubbard and Gross-Pitaevskii dynamics are studied. For the Bose-Hubbard dynamics, we demonstrate that the self-heterodyne protocol can be applied, but higher-order correlations in the evolution of the interfering condensates are measured to readout of the current states of the system. We study how states with macroscopic quantum coherence can be told apart analyzing the noise in the time of flight of the ring condensate.

  2. 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.

  3. 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.

  4. Modeling of Electronic Properties in Organic Semiconductor Device Structures

    Science.gov (United States)

    Chang, Hsiu-Chuang

    Organic semiconductors (OSCs) have recently become viable for a wide range of electronic devices, some of which have already been commercialized. With the mechanical flexibility of organic materials and promising performance of organic field effect transistors (OFETs) and organic bulk heterojunction devices, OSCs have been demonstrated in applications such as radio frequency identification tags, flexible displays, and photovoltaic cells. Transient phenomena play decisive roles in the performance of electronic devices and OFETs in particular. The dynamics of the establishment and depletion of the conducting channel in OFETs are investigated theoretically. The device structures explored resemble typical organic thin-film transistors with one of the channel contacts removed. By calculating the displacement current associated with charging and discharging of the channel in these capacitors, transient effects on the carrier transport in OSCs may be studied. In terms of the relevant models it is shown that the non-linearity of the process plays a key role. The non-linearity arises in the simplest case from the fact that channel resistance varies during the charging and discharging phases. Traps can be introduced into the models and their effects examined in some detail. When carriers are injected into the device, a conducting channel is established with traps that are initially empty. Gradual filling of the traps then modifies the transport characteristics of the injected charge carriers. In contrast, dc measurements as they are typically performed to characterize the transport properties of organic semiconductor channels investigate a steady state with traps partially filled. Numerical and approximate analytical models of the formation of the conducting channel and the resulting displacement currents are presented. For the process of transient carrier extraction, it is shown that if the channel capacitance is partially or completely discharged through the channel

  5. Using Quantum Confinement to Uniquely Identify Devices

    Science.gov (United States)

    Roberts, J.; Bagci, I. E.; Zawawi, M. A. M.; Sexton, J.; Hulbert, N.; Noori, Y. J.; Young, M. P.; Woodhead, C. S.; Missous, M.; Migliorato, M. A.; Roedig, U.; Young, R. J.

    2015-11-01

    Modern technology unintentionally provides resources that enable the trust of everyday interactions to be undermined. Some authentication schemes address this issue using devices that give a unique output in response to a challenge. These signatures are generated by hard-to-predict physical responses derived from structural characteristics, which lend themselves to two different architectures, known as unique objects (UNOs) and physically unclonable functions (PUFs). The classical design of UNOs and PUFs limits their size and, in some cases, their security. Here we show that quantum confinement lends itself to the provision of unique identities at the nanoscale, by using fluctuations in tunnelling measurements through quantum wells in resonant tunnelling diodes (RTDs). This provides an uncomplicated measurement of identity without conventional resource limitations whilst providing robust security. The confined energy levels are highly sensitive to the specific nanostructure within each RTD, resulting in a distinct tunnelling spectrum for every device, as they contain a unique and unpredictable structure that is presently impossible to clone. This new class of authentication device operates with minimal resources in simple electronic structures above room temperature.

  6. Simple Atomic Quantum Memory Suitable for Semiconductor Quantum Dot Single Photons.

    Science.gov (United States)

    Wolters, Janik; Buser, Gianni; Horsley, Andrew; Béguin, Lucas; Jöckel, Andreas; Jahn, Jan-Philipp; Warburton, Richard J; Treutlein, Philipp

    2017-08-11

    Quantum memories matched to single photon sources will form an important cornerstone of future quantum network technology. We demonstrate such a memory in warm Rb vapor with on-demand storage and retrieval, based on electromagnetically induced transparency. With an acceptance bandwidth of δf=0.66  GHz, the memory is suitable for single photons emitted by semiconductor quantum dots. In this regime, vapor cell memories offer an excellent compromise between storage efficiency, storage time, noise level, and experimental complexity, and atomic collisions have negligible influence on the optical coherences. Operation of the memory is demonstrated using attenuated laser pulses on the single photon level. For a 50 ns storage time, we measure η_{e2e}^{50  ns}=3.4(3)% end-to-end efficiency of the fiber-coupled memory, with a total intrinsic efficiency η_{int}=17(3)%. Straightforward technological improvements can boost the end-to-end-efficiency to η_{e2e}≈35%; beyond that, increasing the optical depth and exploiting the Zeeman substructure of the atoms will allow such a memory to approach near unity efficiency. In the present memory, the unconditional read-out noise level of 9×10^{-3} photons is dominated by atomic fluorescence, and for input pulses containing on average μ_{1}=0.27(4) photons, the signal to noise level would be unity.

  7. Simple Atomic Quantum Memory Suitable for Semiconductor Quantum Dot Single Photons

    Science.gov (United States)

    Wolters, Janik; Buser, Gianni; Horsley, Andrew; Béguin, Lucas; Jöckel, Andreas; Jahn, Jan-Philipp; Warburton, Richard J.; Treutlein, Philipp

    2017-08-01

    Quantum memories matched to single photon sources will form an important cornerstone of future quantum network technology. We demonstrate such a memory in warm Rb vapor with on-demand storage and retrieval, based on electromagnetically induced transparency. With an acceptance bandwidth of δ f =0.66 GHz , the memory is suitable for single photons emitted by semiconductor quantum dots. In this regime, vapor cell memories offer an excellent compromise between storage efficiency, storage time, noise level, and experimental complexity, and atomic collisions have negligible influence on the optical coherences. Operation of the memory is demonstrated using attenuated laser pulses on the single photon level. For a 50 ns storage time, we measure ηe2 e 50 ns=3.4 (3 )% end-to-end efficiency of the fiber-coupled memory, with a total intrinsic efficiency ηint=17 (3 )%. Straightforward technological improvements can boost the end-to-end-efficiency to ηe 2 e≈35 %; beyond that, increasing the optical depth and exploiting the Zeeman substructure of the atoms will allow such a memory to approach near unity efficiency. In the present memory, the unconditional read-out noise level of 9 ×10-3 photons is dominated by atomic fluorescence, and for input pulses containing on average μ1=0.27 (4 ) photons, the signal to noise level would be unity.

  8. Monolithically integrated quantum dot optical modulator with Semiconductor optical amplifier for short-range optical communications

    Science.gov (United States)

    Yamamoto, Naokatsu; Akahane, Kouichi; Umezawa, Toshimasa; Kawanishi, Tetsuya

    2015-04-01

    A monolithically integrated quantum dot (QD) optical gain modulator (OGM) with a QD semiconductor optical amplifier (SOA) was successfully developed. Broadband QD optical gain material was used to achieve Gbps-order high-speed optical data transmission, and an optical gain change as high as approximately 6-7 dB was obtained with a low OGM voltage of 2.0 V. Loss of optical power due to insertion of the device was also effectively compensated for by the SOA section. Furthermore, it was confirmed that the QD-OGM/SOA device helped achieve 6.0-Gbps error-free optical data transmission over a 2.0-km-long photonic crystal fiber. We also successfully demonstrated generation of Gbps-order, high-speed, and error-free optical signals in the >5.5-THz broadband optical frequency bandwidth larger than the C-band. These results suggest that the developed monolithically integrated QD-OGM/SOA device will be an advantageous and compact means of increasing the usable optical frequency channels for short-reach communications.

  9. Control of electromagnetically induced transparency via a hybrid semiconductor quantum dot-vanadium dioxide nanoparticle system

    Science.gov (United States)

    Zamani, Naser; Hatef, Ali; Nadgaran, Hamid; Keshavarz, Alireza

    2017-07-01

    We numerically investigate the electromagnetically induced transparency (EIT) of a hybrid system consisting of a three-level quantum dot (QD) in the vicinity of vanadium dioxide nanoparticle (VO2NP). VO2NP has semiconductor and metallic phases where the transition between the two phases occurs around a critical temperature. When the QD-VO2NP hybrid system interacts with continuous wave laser fields in an infrared regime, it supports a coherent coupling of exciton-polariton and exciton-plasmon polariton in semiconductor and metal phases of VO2NP, respectively. In our calculations a filling fraction factor controls the VO2NP phase transition. A probe and control laser field configuration is studied for the hybrid system to measure the absorption of QD through the filling fraction factor manipulations. We show that for the VO2NP semiconductor phase and proper geometrical configuration, the absorption spectrum profile of the QD represents an EIT with two peaks and a clear minimum. These two peaks merge to one through the VO2NP phase transition to metal. We also show that the absorption spectrum profile is modified by different orientations of the laser fields with the axis of the QD-VO2NP hybrid system. The innovation in comparison to other research in the field is that robust variation in the absorption profile through EIT is due to the phase transition in VO2NP without any structural change in the QD-VO2NP hybrid system. Our results can be employed to design nanothermal sensors, optical nanoswitches, and energy transfer devices.

  10. Quantum-engineered interband cascade photovoltaic devices

    Energy Technology Data Exchange (ETDEWEB)

    Razeghi, Manijeh; Tournié, Eric; Brown, Gail J.; Yang, Rui Q.; Lotfi, Hossein; Li, Lu; Hinkey, Robert T.; Ye, Hao; Klem, John F.; Lei, L.; Mishima, T. D.; Keay, J. C.; Santos, M. B.; Johnson, M. B.

    2013-12-18

    Quantum-engineered multiple stage photovoltaic (PV) devices are explored based on InAs/GaSb/AlSb interband cascade (IC) structures. These ICPV devices employ multiple discrete absorbers that are connected in series by widebandgap unipolar barriers using type-II heterostructure interfaces for facilitating carrier transport between cascade stages similar to IC lasers. The discrete architecture is beneficial for improving the collection efficiency and for spectral splitting by utilizing absorbers with different bandgaps. As such, the photo-voltages from each individual cascade stage in an ICPV device add together, creating a high overall open-circuit voltage, similar to conventional multi-junction tandem solar cells. Furthermore, photo-generated carriers can be collected with nearly 100% efficiency in each stage. This is because the carriers travel over only a single cascade stage, designed to be shorter than a typical diffusion length. The approach is of significant importance for operation at high temperatures where the diffusion length is reduced. Here, we will present our recent progress in the study of ICPV devices, which includes the demonstration of ICPV devices at room temperature and above with narrow bandgaps (e.g. 0.23 eV) and high open-circuit voltages. © (2013) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.

  11. Electronic transport in semiconductor nanowires: physics studies and possible device applications

    Science.gov (United States)

    Samuelson, Lars

    2007-03-01

    Semiconductor nanowires are attractive for physics as well as for applications due to the highly ideal character of their electronic and structural properties. We grow our III-V nanowires by what can be described as guided self-assembly, by which we can accurately control location as well as dimensions of epitaxially nucleated nanowires. The level of control of growth allows controlled formation of axial as well as radial heterostructures. I will describe studies of charge transport via single, double and multiple quantum dots positioned inside InAs/InP nanowires. Such studies have allowed detailed studies of the addition of electrons one-by-one, from the very first electron into an empty quantum dot to the addition of up to 50 electrons. By replacing the one-dimensional emitter by a small quantum dot in a double-dot configuration, the discrete character of the injecting state allows ever more detailed spectroscopic studies of the charge additions to the second dot. Comparisons will be made with transport through quantum dots defined by tunnel barriers induced via gating techniques. Finally, a recently developed technique for the formation vertical wrap-gate field-effect transistors around InAs nanowires will be described, suggesting interesting opportunities for the realization of high-speed and low-power transistors and circuits. The geometrical design of such nanowire wrap-gate field-effect transistors, offers exciting ways of formation of ultra-short transistor gate-lengths as well as the use of heterostructures to further enhance the performance of such devices.

  12. Optically Active 3-Dimensional Semiconductor Quantum Dot Assemblies in Heterogeneous Nanoscale Hosts

    Energy Technology Data Exchange (ETDEWEB)

    Nurmikko, Arto V [Brown Univ., Providence, RI (United States). Division of Engineering

    2017-05-07

    Synthesis of semiconductor nanomaterials by low-cost, solution-based methods is shown to lead to new classes of thin film light emitting materials. These materials have been integrated to demonstrative compact laser device testbeds to illustrate their potential for coherent emitters across the visible spectrum to disrupt established photonics technologies, particularly semiconductor lasers?

  13. Multi-valley effective mass theory for device-level modeling of open quantum dynamics

    Science.gov (United States)

    Jacobson, N. Tobias; Baczewski, Andrew D.; Frees, Adam; Gamble, John King; Montano, Ines; Moussa, Jonathan E.; Muller, Richard P.; Nielsen, Erik

    2015-03-01

    Simple models for semiconductor-based quantum information processors can provide useful qualitative descriptions of device behavior. However, as experimental implementations have matured, more specific guidance from theory has become necessary, particularly in the form of quantitatively reliable yet computationally efficient modeling. Besides modeling static device properties, improved characterization of noisy gate operations requires a more sophisticated description of device dynamics. Making use of recent developments in multi-valley effective mass theory, we discuss device-level simulations of the open system quantum dynamics of a qubit interacting with phonons and other noise sources. Sandia is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the US Department of Energy National Nuclear Security Administration under Contract No. DE-AC04-94AL85000.

  14. Optical response of hybrid semiconductor quantum dot-metal nanoparticle system: Beyond the dipole approximation

    Science.gov (United States)

    Mohammadzadeh, Atefeh; Miri, MirFaez

    2018-01-01

    We study the response of a semiconductor quantum dot-metal nanoparticle system to an external field E 0 cos ( ω t ) . The borders between Fano, double peaks, weak transition, strong transition, and bistability regions of the phase diagram move considerably as one regards the multipole effects. The exciton-induced transparency is an artifact of the dipole approximation. The absorption of the nanoparticle, the population inversion of the quantum dot, the upper and lower limits of intensity where bistability occurs, the characteristic time to reach the steady state, and other features of the hybrid system change due to the multipole effects. The phase diagrams corresponding to the fields parallel and perpendicular to the axis of system are quite distinguishable. Thus, both the intensity and the polarization of the incident field can be used to control the system. In particular, the incident polarization can be used to switch on and switch off the bistable behavior. For applications such as miniaturized bistable devices and nanosensors sensitive to variations of the dielectric constant of the surrounding medium, multipole effects must be considered.

  15. THE QUANTUM-WELL STRUCTURES OF SELF ELECTROOPTIC-EFFECT DEVICES AND GALLIUM-ARSENIDE

    Directory of Open Access Journals (Sweden)

    Mustafa TEMİZ

    1996-02-01

    Full Text Available Multiple quantum-well (MQW electroabsorptive self electro optic-effect devices (SEEDs are being extensively studied for use in optical switching and computing. The self electro-optic-effect devices which has quantum-well structures is a new optoelectronic technology with capability to obtain both optical inputs and outputs for Gallium-Arsenide/Aluminum Gallium-Arsenide (GaAs/AlGaAs electronic circuits. The optical inputs and outputs are based on quantum-well absorptive properties. These quantum-well structures consist of many thin layers of semiconductors materials of GaAs/AlGaAs which have emerged some important directions recently. The most important advance in the physics of these materials since the early days has been invention of the heterojunction structures which is based at present on GaAs technology. GaAs/AlGaAs structures present some important advantages to relevant band gap and index of refraction which allow to form the quantum-well structures and also to make semiconductor lasers, dedectors and waveguide optical switches.

  16. Key Topics in Producing New Ultraviolet Led and Laser Devices Based on Transparent Semiconductor Zinc Oxide

    International Nuclear Information System (INIS)

    Tuezemen, S.

    2004-01-01

    Recently, it has been introduced that ZnO as II-VI semiconductor is promising various technological applications, especially for optoelectronic short wavelength light emitting devices due to its wide and direct band gap profile. The most important advantage of ZnO over the other currently used wide band gap semiconductors such as GaN is that its nearly 3 times higher exciton binding energy (60 meV), which permits efficient excitonic emission at room temperature and above. As-grown ZnO is normally n-type because of the Zn-rich defects such as zinc interstitials (Zn i ) oxygen vacancies (Vo), natively acting as shallow donors and main source of n-type conductivity in as-grown material. Therefore, making p-type ZnO has been more difficult due to unintentional compensation of possible acceptors by these residual donors. In order to develop electro luminescent and laser devices based on the ultraviolet (UV) exciton emission of ZnO, it will be important to fabricate good p-n junctions. Attempts to observe p-type conductivity in ours and our collaborators' laboratories in USA, either by co-doping with N or tuning O pressure have been first successful achievements, resulting in hole concentrations up to 10 1 9 cm - 3 in reactively sputtered thin layers of ZnO. Moreover, in order to produce ZnO based quantum well lasers similar to the previously introduced n-AlGaAs/GaAs/p-AlGaAs structures; we have attempted to grow Zn 1 -xSn x O thin films to enlarge the band gap energy. An increase up to 170 meV has been observed in Zn 1 -xSn x O thin films and this is enough barrier to be able to trap electron-hole pairs in quantum well structures. As a result, two important key issues; p-type conductivity and enhancement of the band gap energy in order to step forward towards the production of electro luminescent UV LEDs and quantum well lasers have been investigated and will be presented in this study

  17. High Photoluminescence Quantum Yields in Organic Semiconductor-Perovskite Composite Thin Films.

    Science.gov (United States)

    Longo, Giulia; La-Placa, Maria-Grazia; Sessolo, Michele; Bolink, Henk J

    2017-10-09

    One of the obstacles towards efficient radiative recombination in hybrid perovskites is a low exciton binding energy, typically in the orders of tens of meV. It has been shown that the use of electron-donor additives can lead to a substantial reduction of the non-radiative recombination in perovskite films. Herein, the approach using small molecules with semiconducting properties, which are candidates to be implemented in future optoelectronic devices, is presented. In particular, highly luminescent perovskite-organic semiconductor composite thin films have been developed, which can be processed from solution in a simple coating step. By tuning the relative concentration of methylammonium lead bromide (MAPbBr 3 ) and 9,9spirobifluoren-2-yl-diphenyl-phosphine oxide (SPPO1), it is possible to achieve photoluminescent quantum yields (PLQYs) as high as 85 %. This is attributed to the dual functions of SPPO1 that limit the grain growth while passivating the perovskite surface. The electroluminescence of these materials was investigated by fabricating multilayer LEDs, where charge injection and transport was found to be severely hindered for the perovskite/SPPO1 material. This was alleviated by partially substituting SPPO1 with a hole-transporting material, 1,3-bis(N-carbazolyl)benzene (mCP), leading to bright electroluminescence. The potential of combining perovskite and organic semiconductors to prepare materials with improved properties opens new avenues for the preparation of simple lightemitting devices using perovskites as the emitter. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Broadband microwave phase shifter based on high speed cross gain modulation in quantum dot semiconductor optical amplifiers

    DEFF Research Database (Denmark)

    Chen, Yaohui; Mørk, Jesper

    2009-01-01

    We present a scheme to achieve tunable ~180 degrees microwave phase shifts at frequencies exceeding 100 GHz based on high speed cross gain modulation in quantum dot semiconductor optical amplifiers.......We present a scheme to achieve tunable ~180 degrees microwave phase shifts at frequencies exceeding 100 GHz based on high speed cross gain modulation in quantum dot semiconductor optical amplifiers....

  19. Enhancement of superconducting critical current by injection of quasiparticles in superconductor semiconductor devices

    DEFF Research Database (Denmark)

    Kutchinsky, Jonatan; Taboryski, Rafael Jozef; Sørensen, C. B.

    2000-01-01

    We report new measurements on 3-terminal superconductor semiconductor injection devices, demonstrating enhancement of the supercurrent by injection from a superconducting injector electrode. Two other electrodes were used as detectors. Applying a small voltage to the injector, reduced the maximum...

  20. Nano-scaled semiconductor devices physics, modelling, characterisation, and societal impact

    CERN Document Server

    Gutiérrez-D, Edmundo A

    2016-01-01

    This book describes methods for the characterisation, modelling, and simulation prediction of these second order effects in order to optimise performance, energy efficiency and new uses of nano-scaled semiconductor devices.

  1. Nonlinear structures: Cnoidal, soliton, and periodical waves in quantum semiconductor plasma

    Energy Technology Data Exchange (ETDEWEB)

    Tolba, R. E., E-mail: tolba-math@yahoo.com; El-Bedwehy, N. A., E-mail: nab-elbedwehy@yahoo.com [Department of Mathematics, Faculty of Science Damietta University, New Damietta 34517 (Egypt); Moslem, W. M., E-mail: wmmoslem@hotmail.com [Department of Physics, Faculty of Science Port Said University, Port Said 42521 (Egypt); Centre for Theoretical Physics, The British University in Egypt (BUE), El-Shorouk City, Cairo (Egypt); El-Labany, S. K., E-mail: skellabany@hotmail.com [Department of Physics, Faculty of Science Damietta University, New Damietta 34517 (Egypt); Yahia, M. E., E-mail: meyahia@gmail.com [Faculty of Engineering and Natural Sciences, International University of Sarajevo (IUS), 71210 Ilidža, Sarajevo, Bosnia and Herzegovina (Bosnia and Herzegovina)

    2016-01-15

    Properties and emerging conditions of various nonlinear acoustic waves in a three dimensional quantum semiconductor plasma are explored. A plasma fluid model characterized by degenerate pressures, exchange correlation, and quantum recoil forces is established and solved. Our analysis approach is based on the reductive perturbation theory for deriving the Kadomtsev-Petviashvili equation from the fluid model and solving it by using Painlevé analysis to come up with different nonlinear solutions that describe different pulse profiles such as cnoidal, soliton, and periodical pulses. The model is then employed to recognize the possible perturbations in GaN semiconductor.

  2. Enhancing slow- and fast-light effects in quantum dot semiconductor waveguides through ultrafast dynamics

    DEFF Research Database (Denmark)

    Chen, Yaohui; Mørk, Jesper

    2011-01-01

    In this paper we review our theoretical work on slow and fast light effects in quantum dot semiconductor optical amplifiers (QD SOAs), in particular we investigate the carrier dynamical contributions to the dynamic gain grating and cross gain modulation induced by unique ultrafast inter-subband c......In this paper we review our theoretical work on slow and fast light effects in quantum dot semiconductor optical amplifiers (QD SOAs), in particular we investigate the carrier dynamical contributions to the dynamic gain grating and cross gain modulation induced by unique ultrafast inter...

  3. Optical properties of colloidal semiconductor quantum dots in dielectric media: A natural potential well approach

    Science.gov (United States)

    Jeong, Hwajun; Shin, Seung Koo

    2018-01-01

    Colloidal quantum dots exhibit size-dependent optical properties due to quantum and dielectric confinements at the semiconductor/solvent boundary. To consider both confinement effects, we take a natural potential well approach that assumes separate potential wells for electron and hole which are surrounded by dielectric media. The potential well depths for electron and hole are set by the band offsets at the semiconductor/solvent heterojunction. The kinetic energy is calculated using an effective mass approximation and the electron-hole interaction energy is obtained by taking image charges into account. For cadmium chalcogenides, resulting transition energies agree well with size-dependent optical bandgaps from experiments.

  4. Critical components for diamond-based quantum coherent devices

    International Nuclear Information System (INIS)

    Greentree, Andrew D; Olivero, Paolo; Draganski, Martin; Trajkov, Elizabeth; Rabeau, James R; Reichart, Patrick; Gibson, Brant C; Rubanov, Sergey; Huntington, Shane T; Jamieson, David N; Prawer, Steven

    2006-01-01

    The necessary elements for practical devices exploiting quantum coherence in diamond materials are summarized, and progress towards their realization documented. A brief review of future prospects for diamond-based devices is also provided

  5. Ion implantation in compound semiconductors for high-performance electronic devices

    International Nuclear Information System (INIS)

    Zolper, J.C.; Baca, A.G.; Sherwin, M.E.; Klem, J.F.

    1996-01-01

    Advanced electronic devices based on compound semiconductors often make use of selective area ion implantation doping or isolation. The implantation processing becomes more complex as the device dimensions are reduced and more complex material systems are employed. The authors review several applications of ion implantation to high performance junction field effect transistors (JFETs) and heterostructure field effect transistors (HFETs) that are based on compound semiconductors, including: GaAs, AlGaAs, InGaP, and AlGaSb

  6. Nonequilibrium spin transport through a diluted magnetic semiconductor quantum dot system with noncollinear magnetization

    International Nuclear Information System (INIS)

    Ma, Minjie; Jalil, Mansoor Bin Abdul; Tan, Seng Gee

    2013-01-01

    The spin-dependent transport through a diluted magnetic semiconductor quantum dot (QD) which is coupled via magnetic tunnel junctions to two ferromagnetic leads is studied theoretically. A noncollinear system is considered, where the QD is magnetized at an arbitrary angle with respect to the leads’ magnetization. The tunneling current is calculated in the coherent regime via the Keldysh nonequilibrium Green’s function (NEGF) formalism, incorporating the electron–electron interaction in the QD. We provide the first analytical solution for the Green’s function of the noncollinear DMS quantum dot system, solved via the equation of motion method under Hartree–Fock approximation. The transport characteristics (charge and spin currents, and tunnel magnetoresistance (TMR)) are evaluated for different voltage regimes. The interplay between spin-dependent tunneling and single-charge effects results in three distinct voltage regimes in the spin and charge current characteristics. The voltage range in which the QD is singly occupied corresponds to the maximum spin current and greatest sensitivity of the spin current to the QD magnetization orientation. The QD device also shows transport features suitable for sensor applications, i.e., a large charge current coupled with a high TMR ratio. - Highlights: ► The spin polarized transport through a diluted magnetic quantum dot is studied. ► The model is based on the Green’s function and the equation of motion method.► The charge and spin currents and tunnel magnetoresistance (TMR) are investigated. ► The system is suitable for current-induced spin-transfer torque application. ► A large tunneling current and a high TMR are possible for sensor application.

  7. Classification of methods for measuring current-voltage characteristics of semiconductor devices

    Directory of Open Access Journals (Sweden)

    Iermolenko Ia. O.

    2014-06-01

    Full Text Available It is shown that computer systems for measuring current-voltage characteristics are very important for semiconductor devices production. The main criteria of efficiency of such systems are defined. It is shown that efficiency of such systems significantly depends on the methods for measuring current-voltage characteristics of semiconductor devices. The aim of this work is to analyze existing methods for measuring current-voltage characteristics of semiconductor devices and to create the classification of these methods in order to specify the most effective solutions in terms of defined criteria. To achieve this aim, the most common classifications of methods for measuring current-voltage characteristics of semiconductor devices and their main disadvantages are considered. Automated and manual, continuous, pulse, mixed, isothermal and isodynamic methods for measuring current-voltage characteristics are analyzed. As a result of the analysis and generalization of existing methods the next classification criteria are defined: the level of automation, the form of measurement signals, the condition of semiconductor device during the measurements, and the use of mathematical processing of the measurement results. With the use of these criteria the classification scheme of methods for measuring current-voltage characteristics of semiconductor devices is composed and the most effective methods are specified.

  8. Radiation hardness and qualification of semiconductor electronic devices for nuclear reactors

    International Nuclear Information System (INIS)

    Friant, A.; Payat, R.

    1984-05-01

    After a brief review of radiation effects in semiconductors and radiation damage in semiconductor devices, the problems of qualification of electronic equipment to be used in nuclear reactors are compared to those relative to nuclear weapons or space experiments. The conclusion is that data obtained at very high dose rates or under pulsed irradiation in weapons and space programs should not be directly applied to nuclear plant instrumentation. The need for a specific qualification of semiconductor devices appropriate for nuclear reactors is emphasized. Some irradiation studies at IRDI/DEIN (CEN-Saclay) are related [fr

  9. A new generation of high-power semiconductor devices

    Directory of Open Access Journals (Sweden)

    Drndarević Vujo R.

    2014-01-01

    Full Text Available Due to the constant development of technology and production, silicon semiconductor electronic components reach performance approaching the theoretical characteristics of the material. However, in many applications, especially in the field of power electronics, the available Si components can not meet the demands that are placed on the issue of operating voltage, switching frequency, efficiency and reliability. In order to overcome the resulting limitations, intensive research of new semiconductor materials that enable cost-effective implementation of semiconductor components with required characteristics are carried out. This paper presents a comparative analysis of semiconductor materials with wide energy band gap bearing in mind the possibility of their application in the field of power electronics and provides an overview of commercially available switching components implemented using new technologies and materials.

  10. Colloidal quantum dot light-emitting devices

    Directory of Open Access Journals (Sweden)

    Vanessa Wood

    2010-07-01

    Full Text Available Colloidal quantum dot light-emitting devices (QD-LEDs have generated considerable interest for applications such as thin film displays with improved color saturation and white lighting with a high color rendering index (CRI. We review the key advantages of using quantum dots (QDs in display and lighting applications, including their color purity, solution processability, and stability. After highlighting the main developments in QD-LED technology in the past 15 years, we describe the three mechanisms for exciting QDs – optical excitation, Förster energy transfer, and direct charge injection – that have been leveraged to create QD-LEDs. We outline the challenges facing QD-LED development, such as QD charging and QD luminescence quenching in QD thin films. We describe how optical downconversion schemes have enabled researchers to overcome these challenges and develop commercial lighting products that incorporate QDs to achieve desirable color temperature and a high CRI while maintaining efficiencies comparable to inorganic white LEDs (>65 lumens per Watt. We conclude by discussing some current directions in QD research that focus on achieving higher efficiency and air-stable QD-LEDs using electrical excitation of the luminescent QDs.

  11. 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

  12. Exploring graphene field effect transistor devices to improve spectral resolution of semiconductor radiation detectors

    Energy Technology Data Exchange (ETDEWEB)

    Harrison, Richard Karl [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Howell, Stephen Wayne [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Martin, Jeffrey B. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Hamilton, Allister B. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2013-12-01

    Graphene, a planar, atomically thin form of carbon, has unique electrical and material properties that could enable new high performance semiconductor devices. Graphene could be of specific interest in the development of room-temperature, high-resolution semiconductor radiation spectrometers. Incorporating graphene into a field-effect transistor architecture could provide an extremely high sensitivity readout mechanism for sensing charge carriers in a semiconductor detector, thus enabling the fabrication of a sensitive radiation sensor. In addition, the field effect transistor architecture allows us to sense only a single charge carrier type, such as electrons. This is an advantage for room-temperature semiconductor radiation detectors, which often suffer from significant hole trapping. Here we report on initial efforts towards device fabrication and proof-of-concept testing. This work investigates the use of graphene transferred onto silicon and silicon carbide, and the response of these fabricated graphene field effect transistor devices to stimuli such as light and alpha radiation.

  13. 2-Dimensional coupled algorithm for simulating dose-rate transient effects of semiconductor devices

    International Nuclear Information System (INIS)

    Wei Yuan; Huang Liuxing; Gong Ding; Niu Shengli

    2010-01-01

    Most commercial semiconductor simulators introduce an analytical equation to calculate the energy deposited by particles or gamma ray when simulating radiation effects of semiconductor devices. However, this method is insufficient as the size of devices becomes smaller and smaller. In order to solve the limitation of analytical method, this paper presents a 2-dimensional algorithm for calculating dose-rate transient response of semiconductor devices by coupling Finite Volume method with Monte Carlo method, which is used to trace the history of particles and generate the distribution of deposited energy. An integrated program is established by combining an open source semiconductor simulator named GSS and a Monte Carlo code. And the computational results for two reverse biased diodes with different structures are compared with MEDICI's and Enlow's theoretical photocurrent model. It shows that the coupled algorithm is consistent with traditional analytical method and Enlow's model. (author)

  14. High-rate measurement-device-independent quantum cryptography

    DEFF Research Database (Denmark)

    Pirandola, Stefano; Ottaviani, Carlo; Spedalieri, Gaetana

    2015-01-01

    Quantum cryptography achieves a formidable task - the remote distribution of secret keys by exploiting the fundamental laws of physics. Quantum cryptography is now headed towards solving the practical problem of constructing scalable and secure quantum networks. A significant step in this direction...... than those currently achieved. Our protocol could be employed to build high-rate quantum networks where devices securely connect to nearby access points or proxy servers....

  15. Generic Hubbard model description of semiconductor quantum-dot spin qubits

    Science.gov (United States)

    Yang, Shuo; Wang, Xin; Das Sarma, S.

    2011-04-01

    We introduce a Hubbard model as the simple quantum generalization of the classical capacitance circuit model to study semiconductor quantum-dot spin qubits. We prove theoretically that our model is equivalent to the usual capacitance circuit model in the absence of quantum fluctuations. However, our model naturally includes quantum effects such as hopping and spin exchange. The parameters of the generalized Hubbard model can either be directly read off from the experimental plot of the stability diagram or be calculated from the microscopic theory, establishing a quantitative connection between the two. We show that, while the main topology of the charge stability diagram is determined by the ratio between intersite and on-site Coulomb repulsion, fine details of the stability diagram reveal information about quantum effects. Extracting quantum information from experiments using our Hubbard model approach is simple, but would require the measurement resolution to increase by an order of magnitude.

  16. Signatures of Quantized Energy States in Solution-Processed Ultrathin Layers of Metal-Oxide Semiconductors and Their Devices

    KAUST Repository

    Labram, John G.

    2015-02-13

    Physical phenomena such as energy quantization have to-date been overlooked in solution-processed inorganic semiconducting layers, owing to heterogeneity in layer thickness uniformity unlike some of their vacuum-deposited counterparts. Recent reports of the growth of uniform, ultrathin (<5 nm) metal-oxide semiconductors from solution, however, have potentially opened the door to such phenomena manifesting themselves. Here, a theoretical framework is developed for energy quantization in inorganic semiconductor layers with appreciable surface roughness, as compared to the mean layer thickness, and present experimental evidence of the existence of quantized energy states in spin-cast layers of zinc oxide (ZnO). As-grown ZnO layers are found to be remarkably continuous and uniform with controllable thicknesses in the range 2-24 nm and exhibit a characteristic widening of the energy bandgap with reducing thickness in agreement with theoretical predictions. Using sequentially spin-cast layers of ZnO as the bulk semiconductor and quantum well materials, and gallium oxide or organic self-assembled monolayers as the barrier materials, two terminal electronic devices are demonstrated, the current-voltage characteristics of which resemble closely those of double-barrier resonant-tunneling diodes. As-fabricated all-oxide/hybrid devices exhibit a characteristic negative-differential conductance region with peak-to-valley ratios in the range 2-7.

  17. Magnetosonic solitons in semiconductor plasmas in the presence of quantum tunneling and exchange correlation effects

    Science.gov (United States)

    Hussain, S.; Mahmood, S.

    2018-01-01

    Low frequency magnetosonic wave excitations are investigated in semiconductor hole-electron plasmas. The quantum mechanical effects such as Fermi pressure, quantum tunneling, and exchange-correlation of holes and electrons in the presence of the magnetic field are considered. The two fluid quantum magnetohydrodynamic model is used to study magnetosonic wave dynamics, while electric and magnetic fields are coupled via Maxwell equations. The dispersion relation of the magnetosonic wave in electron-hole semiconductor plasma propagating in the perpendicular direction of the magnetic field is obtained, and its dispersion effects are discussed. The Korteweg-de Vries equation (KdV) for magnetosonic solitons is derived by employing the reductive perturbation method. For numerical analysis, the plasma parameters are taken from the semiconductors such as GaAs, GaSb, GaN, and InP already existing in the literature. It is found that the phase velocity of the magnetosonic wave is increased with the inclusion of exchange-correlation force in the model. The soliton dip structures of the magnetosonic wave in GaN semiconductor plasma are obtained, which satisfy the quantum plasma conditions for electron and hole fluids. The magnetosonic soliton dip structures move with speed less than the magnetosonic wave phase speed in the lab frame. The effects of exchange-correlation force in the model and variations of magnetic field intensity and electron/hole density on the magnetosonic wave dip structures are also investigated numerically for illustration.

  18. Carrier-carrier relaxation kinetics in quantum well semiconductor structures with nonparabolic energy bands

    DEFF Research Database (Denmark)

    Dery, H.; Tromborg, Bjarne; Eisenstein, G.

    2003-01-01

    We describe carrier-carrier scattering dynamics in an inverted quantum well structure including the nonparabolic nature of the valance band. A solution of the semiconductor Bloch equations yields strong evidence to a large change in the temporal evolution of the carrier distributions compared...

  19. Spectroscopic quantum imaging using pixel-level ADCS in Semiconductor-based Hybrid pixel detectors

    NARCIS (Netherlands)

    San Segundo Bello, D.

    2009-01-01

    This thesis describes the design of a microelectronic system that can be used to build a spectroscopic imaging system, in particular a spectroscopic quantum imaging using pixel-level ADCs in semiconductor-based hybrid pixel detectors. In such a system the signal generated in the sensor by a photon

  20. Self-slowdown and -advancement of fs pulses in a quantum-dot semiconductor optical amplifier

    DEFF Research Database (Denmark)

    Poel, Mike van der; Mørk, Jesper; Hvam, Jørn Märcher

    2005-01-01

    We demonstrate changes in the propagation time of 180 femtosecond pulses in a quantum-dot semiconductor optical amplifier as function of pulse input power and bias current. The results interpreted as a result of pulse reshaping by gain saturation but are also analogous to coherent population osci...

  1. Quantum wells, wires and dots theoretical and computational physics of semiconductor nanostructures

    CERN Document Server

    Harrison, Paul

    2016-01-01

    Quantum Wells, Wires and Dots provides all the essential information, both theoretical and computational, to develop an understanding of the electronic, optical and transport properties of these semiconductor nanostructures. The book will lead the reader through comprehensive explanations and mathematical derivations to the point where they can design semiconductor nanostructures with the required electronic and optical properties for exploitation in these technologies. This fully revised and updated 4th edition features new sections that incorporate modern techniques and extensive new material including: - Properties of non-parabolic energy bands - Matrix solutions of the Poisson and Schrodinger equations - Critical thickness of strained materials - Carrier scattering by interface roughness, alloy disorder and impurities - Density matrix transport modelling -Thermal modelling Written by well-known authors in the field of semiconductor nanostructures and quantum optoelectronics, this user-friendly guide is pr...

  2. High-resolution photoluminescence studies of single semiconductor quantum dots

    DEFF Research Database (Denmark)

    Leosson, Kristjan; Østergaard, John Erland; Jensen, Jacob Riis

    2000-01-01

    developed in the study of single quantum dots, characterized by sharp atomic-like transition lines revealing their zero-dimensional density of states. Substantial information about the fundamental properties of individual quantum dots, as well as their interactions with other dots and the host lattice, can...

  3. DSP control of superconducting quantum interference devices

    Energy Technology Data Exchange (ETDEWEB)

    Bracht, R.R.; Kung, Pang-Jen; Lewis, P.S.; Flynn, E.R.

    1994-08-01

    Superconducting quantum interference devices (SQUIDS) are used to defect very law level magnetic fields. Los Alamos National Laboratory is involved in developing digital signal processing (DSP) based instrumentation for these devices in conjunction with detecting magnetic flux from the human brain. This field of application is known as magnetoencephalography (MEG). The magnetic signals generated by the brain are on the order of a billion times smaller than the earth`s magnetic field, yet they can readily be detected with these highly ,sensitive magnetic detectors. Los Alamos National Laboratory has developed and implemented DSP control of the SQUID system. This has been accomplished by using an AT&T DSP32C DSP in conjunction with dual 18 bit a-to-d and d-to-a converters. The DSP performs the signal demodulation by synchronously sampling the recovered signal and applying the appropriate full wave rectification. The signal is then integrated and filtered and applied to the output. Also, the modulation signal is generated with the DSP system. All of the flux lock loop electronics are replaced except for the low noise analog preamplifier at the front of the recovery components. The system has been tested with both an electronic SQUID simulator and a low temperature thin film SQUID from Conductus. A number of experiments have been performed to allow evaluation of the system improvement made possible by use of DSP control.

  4. Near-field optical spectroscopy of semiconductor quantum wires

    Science.gov (United States)

    Gershoni, D.; Harris, T. D.; Pfeiffer, L. N.

    1997-09-01

    We discuss low temperature near-field scanning optical spectroscopical studies of single, nanometer dimension, cleaved edge overgrown quantum wires. We use the enhanced spatial resolution of near-field microscopy, to spectroscopically investigate these single wires, which are inaccessible to conventional far-field optical spectroscopy. We thus performed a direct experimental comparison between a two-dimensional quantum system and a single genuine one-dimensional quantum system. We show that the photoluminescence of a single quantum wire is easily distinguished from that of the surrounding quantum well. Emission from localized centers is shown to dominate the photoluminescence from both wires and wells at low temperatures. A factor of three enhancement in the optical absorption of a wire, in comparison with that of a similar well, is concluded from the photoluminescence excitation data.

  5. Temperature-dependent resonance energy transfer from semiconductor quantum wells to graphene.

    Science.gov (United States)

    Yu, Young-Jun; Kim, Keun Soo; Nam, Jungtae; Kwon, Se Ra; Byun, Hyeryoung; Lee, Kwanjae; Ryou, Jae-Hyun; Dupuis, Russell D; Kim, Jeomoh; Ahn, Gwanghyun; Ryu, Sunmin; Ryu, Mee-Yi; Kim, Jin Soo

    2015-02-11

    Resonance energy transfer (RET) has been employed for interpreting the energy interaction of graphene combined with semiconductor materials such as nanoparticles and quantum-well (QW) heterostructures. Especially, for the application of graphene as a transparent electrode for semiconductor light emitting diodes, the mechanism of exciton recombination processes such as RET in graphene-semiconductor QW heterojunctions should be understood clearly. Here, we characterized the temperature-dependent RET behaviors in graphene/semiconductor QW heterostructures. We then observed the tuning of the RET efficiency from 5% to 30% in graphene/QW heterostructures with ∼60 nm dipole-dipole coupled distance at temperatures of 300 to 10 K. This survey allows us to identify the roles of localized and free excitons in the RET process from the QWs to graphene as a function of temperature.

  6. Controlling the Photophysical Properties of Semiconductor Quantum Dot Arrays by Strategically Altering Their Surface Chemistry

    Science.gov (United States)

    Marshall, Ashley R.

    Semiconductor quantum dots (QDs) are interesting materials that, after less than 40 years of research, are used in commercial products. QDs are now found in displays, such as Samsung televisions and the Kindle Fire, and have applications in lighting, bio-imaging, quantum computing, and photovoltaics. They offer a large range of desirable properties: a controllable band gap, solution processability, controlled energy levels, and are currently the best materials for multiple exciton generation. The tunable optoelectronic properties of QDs can be controlled using size, shape, composition, and surface treatments--as shown here. Due to the quasi-spherical shape of QDs the surface to volume ratio is high, i.e. many of the constituent atoms are found on the QD surface. This makes QDs highly sensitive to surface chemistry modifications. This thesis encompasses the effects of surface treatments for QDs of two semiconducting materials: lead chalcogenides and CsPbI3. Our group developed a new synthetic technique for lead chalcogenide QDs via the cation exchange of cadmium chalcogenides. An in-depth chemical analysis is paired with optical and electrical studies and we find that metal halide residue contributes to the oxidative stability and decreased trap state density in cation-exchanged PbS QDs. We exploit these properties to make air-stable QD photovoltaic devices from both PbS and PbSe QD materials. Beyond the effects of residual atoms left from the synthetic technique, I investigated how to controllably add atoms onto the surface of QDs. I found that by introducing metal halides as a post-treatment in an electronically coupled array I am able to control the performance parameters in QD photovoltaic devices. These treatments fully infiltrate the assembled film, even under short exposure times and allow me to add controlled quantities of surface atoms to study their effects on film properties and photovoltaic device performance. Finally, I sought to apply the knowledge of

  7. Electron Transport in Quantum Dots Defined in Low-Dimensional Semiconductor Structures

    OpenAIRE

    Larsson, Marcus

    2011-01-01

    This thesis focuses on electron transport in single and double quantum dots defined in low-dimensional, narrow-band-gap III-V semiconductor materials. Fabrication schemes are presented for defining single and double quantum dots in lateral InGaAs/InP heterostructures, either by a combination of etching and local gating or solely by local top gating. The quantum dots are here electrostatically confined in at least one dimension. This allows for insitu control of the tunnel coupling of the quan...

  8. Spin dynamics and hyperfine interaction in InAs semiconductor quantum dots

    International Nuclear Information System (INIS)

    Eble, B.; Krebs, O.; Voisin, P.; Lemaitre, A.; Kudelski, A.; Braun, P.F.; Lombez, L.; Marie, X.; Urbaszek, B.; Amand, T.; Lagarde, D.; Renucci, P.; Kowalik, K.; Kalevich, V.K.; Kavokin, K.V.

    2006-01-01

    We present a detailed study of the hyperfine interaction between carrier and nuclear spins in InAs semiconductor quantum dots. Time resolved measurements on excitons in positively charged quantum dots show the electron spin relaxation due to random fluctuations of the spin orientation of the nuclei in the quantum dot. A complimentary aspect of the hyperfine interaction can be uncovered in single dot continuous wave photoluminescence experiments in a weak magnetic field, namely the Overhauser shift due to the dynamic polarisation of the nuclei following excitation with circularly polarised light. (copyright 2006 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  9. Quantum transport in nanowire-based hybrid devices

    Energy Technology Data Exchange (ETDEWEB)

    Guenel, Haci Yusuf

    2013-05-08

    We have studied the low-temperature transport properties of nanowires contacted by a normal metal as well as by superconducting electrodes. As a consequence of quantum coherence, we have demonstrated the electron interference effect in different aspects. The mesoscopic phase coherent transport properties were studied by contacting the semiconductor InAs and InSb nanowires with normal metal electrodes. Moreover, we explored the interaction of the microscopic quantum coherence of the nanowires with the macroscopic quantum coherence of the superconductors. In superconducting Nb contacted InAs nanowire junctions, we have investigated the effect of temperature, magnetic field and electric field on the supercurrent. Owing to relatively high critical temperature of superconducting Nb (T{sub c} ∝ 9 K), we have observed the supercurrent up to 4 K for highly doped nanowire-based junctions, while for low doped nanowire-based junctions a full control of the supercurrent was achieved. Due to low transversal dimension of the nanowires, we have found a monotonous decay of the critical current in magnetic field dependent measurements. The experimental results were analyzed within narrow junction model which has been developed recently. At high bias voltages, we have observed subharmonic energy gap structures as a consequence of multiple Andreev reflection. Some of the nanowires were etched, such that the superconducting Nb electrodes are connected to both ends of the nanowire rather than covering the surface of the nanowire. As a result of well defined nanowire-superconductor interfaces, we have examined quasiparticle interference effect in magnetotransport measurements. Furthermore, we have developed a new junction geometry, such that one of the superconducting Nb electrodes is replaced by a superconducting Al. Owing to the smaller critical magnetic field of superconducting Al (B{sub c} ∝ 15-50,mT), compared to superconducting Nb (B{sub c} ∝ 3 T), we were able to studied

  10. Andreev molecules in semiconductor nanowire double quantum dots.

    Science.gov (United States)

    Su, Zhaoen; Tacla, Alexandre B; Hocevar, Moïra; Car, Diana; Plissard, Sébastien R; Bakkers, Erik P A M; Daley, Andrew J; Pekker, David; Frolov, Sergey M

    2017-09-19

    Chains of quantum dots coupled to superconductors are promising for the realization of the Kitaev model of a topological superconductor. While individual superconducting quantum dots have been explored, control of longer chains requires understanding of interdot coupling. Here, double quantum dots are defined by gate voltages in indium antimonide nanowires. High transparency superconducting niobium titanium nitride contacts are made to each of the dots in order to induce superconductivity, as well as probe electron transport. Andreev bound states induced on each of dots hybridize to define Andreev molecular states. The evolution of these states is studied as a function of charge parity on the dots, and in magnetic field. The experiments are found in agreement with a numerical model.Quantum dots in a nanowire are one possible approach to creating a solid-state quantum simulator. Here, the authors demonstrate the coupling of electronic states in a double quantum dot to form Andreev molecule states; a potential building block for longer chains suitable for quantum simulation.

  11. Color-selective photodetection from intermediate colloidal quantum dots buried in amorphous-oxide semiconductors.

    Science.gov (United States)

    Cho, Kyung-Sang; Heo, Keun; Baik, Chan-Wook; Choi, Jun Young; Jeong, Heejeong; Hwang, Sungwoo; Lee, Sang Yeol

    2017-10-10

    We report color-selective photodetection from intermediate, monolayered, quantum dots buried in between amorphous-oxide semiconductors. The proposed active channel in phototransistors is a hybrid configuration of oxide-quantum dot-oxide layers, where the gate-tunable electrical property of silicon-doped, indium-zinc-oxide layers is incorporated with the color-selective properties of quantum dots. A remarkably high detectivity (8.1 × 10 13 Jones) is obtained, along with three major findings: fast charge separation in monolayered quantum dots; efficient charge transport through high-mobility oxide layers (20 cm 2  V -1  s -1 ); and gate-tunable drain-current modulation. Particularly, the fast charge separation rate of 3.3 ns -1 measured with time-resolved photoluminescence is attributed to the intermediate quantum dots buried in oxide layers. These results facilitate the realization of efficient color-selective detection exhibiting a photoconductive gain of 10 7 , obtained using a room-temperature deposition of oxide layers and a solution process of quantum dots. This work offers promising opportunities in emerging applications for color detection with sensitivity, transparency, and flexibility.The development of highly sensitive photodetectors is important for image sensing and optical communication applications. Cho et al., report ultra-sensitive photodetectors based on monolayered quantum dots buried in between amorphous-oxide semiconductors and demonstrate color-detecting logic gates.

  12. Space- and time-dependent quantum dynamics of spatially indirect excitons in semiconductor heterostructures

    Energy Technology Data Exchange (ETDEWEB)

    Grasselli, Federico, E-mail: federico.grasselli@unimore.it; Goldoni, Guido, E-mail: guido.goldoni@unimore.it [Department of Physics, Informatics and Mathematics, University of Modena and Reggio Emilia, Modena (Italy); CNR-NANO S3, Institute for Nanoscience, Via Campi 213/a, 41125 Modena (Italy); Bertoni, Andrea, E-mail: andrea.bertoni@nano.cnr.it [CNR-NANO S3, Institute for Nanoscience, Via Campi 213/a, 41125 Modena (Italy)

    2015-01-21

    We study the unitary propagation of a two-particle one-dimensional Schrödinger equation by means of the Split-Step Fourier method, to study the coherent evolution of a spatially indirect exciton (IX) in semiconductor heterostructures. The mutual Coulomb interaction of the electron-hole pair and the electrostatic potentials generated by external gates and acting on the two particles separately are taken into account exactly in the two-particle dynamics. As relevant examples, step/downhill and barrier/well potential profiles are considered. The space- and time-dependent evolutions during the scattering event as well as the asymptotic time behavior are analyzed. For typical parameters of GaAs-based devices, the transmission or reflection of the pair turns out to be a complex two-particle process, due to comparable and competing Coulomb, electrostatic, and kinetic energy scales. Depending on the intensity and anisotropy of the scattering potentials, the quantum evolution may result in excitation of the IX internal degrees of freedom, dissociation of the pair, or transmission in small periodic IX wavepackets due to dwelling of one particle in the barrier region. We discuss the occurrence of each process in the full parameter space of the scattering potentials and the relevance of our results for current excitronic technologies.

  13. Quantitative Determination of Organic Semiconductor Microstructure from the Molecular to Device Scale

    KAUST Repository

    Rivnay, Jonathan

    2012-10-10

    A study was conducted to demonstrate quantitative determination of organic semiconductor microstructure from the molecular to device scale. The quantitative determination of organic semiconductor microstructure from the molecular to device scale was key to obtaining precise description of the molecular structure and microstructure of the materials of interest. This information combined with electrical characterization and modeling allowed for the establishment of general design rules to guide future rational design of materials and devices. Investigations revealed that a number and variety of defects were the largest contributors to the existence of disorder within a lattice, as organic semiconductor crystals were dominated by weak van der Waals bonding. Crystallite size, texture, and variations in structure due to spatial confinement and interfaces were also found to be relevant for transport of free charge carriers and bound excitonic species over distances that were important for device operation.

  14. Measurement of the transient response of semiconductor devices to ionizing radiation

    International Nuclear Information System (INIS)

    McMorrow, Dale; Boos, J. Brad; Melinger, Joseph S.; Ferlet-Cavrois, Veronique; Paillet, Philippe; Duhamel, Olivier; Baggio, Jacques

    2007-01-01

    Recent developments in the measurement of heavy-ion induced charge-collection transients of semiconductor devices are described. The information content of transient SET measurement is significantly enhanced relative to that of conventional charge-collection measurement. Examples of recent measurements on InP HEMT and SOI NMOS devices are presented

  15. High Temperature Superconductor/Semiconductor Hybrid Microwave Devices and Circuits

    Science.gov (United States)

    Romanofsky, Robert R.; Miranda, Felix A.

    1999-01-01

    Contents include following: film deposition technique; laser ablation; magnetron sputtering; sequential evaporation; microwave substrates; film characterization at microwave frequencies; complex conductivity; magnetic penetration depth; surface impedance; planar single-mode filters; small antennas; antenna arrays phase noise; tunable oscillations; hybrid superconductor/semiconductor receiver front ends; and noise modeling.

  16. Nodal ground states and orbital textures in semiconductor quantum dots

    Czech Academy of Sciences Publication Activity Database

    Lee, J.; Výborný, Karel; Han, J.E.; Žutič, I.

    2014-01-01

    Roč. 89, č. 4 (2014), "045315-1"-"045315-17" ISSN 1098-0121 Institutional support: RVO:68378271 Keywords : quantum dots * electronic structure Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.736, year: 2014

  17. Light Scattering Spectroscopies of Semiconductor Nanocrystals (Quantum Dots)

    International Nuclear Information System (INIS)

    Yu, Peter Y; Gardner, Grat; Nozaki, Shinji; Berbezier, Isabelle

    2006-01-01

    We review the study of nanocrystals or quantum dots using inelastic light scattering spectroscopies. In particular recent calculations of the phonon density of states and low frequency Raman spectra in Ge nanocrystals are presented for comparison with experimental results

  18. Nanobubble induced formation of quantum emitters in monolayer semiconductors

    Science.gov (United States)

    Shepard, Gabriella D.; Ajayi, Obafunso A.; Li, Xiangzhi; Zhu, X.-Y.; Hone, James; Strauf, Stefan

    2017-06-01

    The recent discovery of exciton quantum emitters in transition metal dichalcogenides (TMDCs) has triggered renewed interest of localized excitons in low-dimensional systems. Open questions remain about the microscopic origin previously attributed to dopants and/or defects as well as strain potentials. Here we show that the quantum emitters can be deliberately induced by nanobubble formation in WSe2 and BN/WSe2 heterostructures. Correlations of atomic-force microscope and hyperspectral photoluminescence images reveal that the origin of quantum emitters and trion disorder is extrinsic and related to 10 nm tall nanobubbles and 70 nm tall wrinkles, respectively. We further demonstrate that ‘hot stamping’ results in the absence of 0D quantum emitters and trion disorder. The demonstrated technique is useful for advances in nanolasers and deterministic formation of cavity-QED systems in monolayer materials.

  19. Quantum Dots in Vertical Nanowire Devices

    NARCIS (Netherlands)

    Van Weert, M.

    2010-01-01

    The research described in this thesis is aimed at constructing a quantum interface between a single electron spin and a photon, using a nanowire quantum dot. Such a quantum interface enables information transfer from a local electron spin to the polarization of a photon for long distance readout.

  20. Photon-Storage in Optical Memory Cells Based on a Semiconductor Quantum Dot-Quantum Well Hybrid Structure

    Science.gov (United States)

    Bian, Song-Bao; Tang, Yan; Li, Gui-Rong; Li, Yue-Xia; Yang, Fu-Hua; Zheng, Hou-Zhi; Zeng, Yi-Ping

    2003-08-01

    We report a new type of photonic memory cell based on a semiconductor quantum dot (QD)-quantum well (QW) hybrid structure, in which photo-generated excitons can be decomposed into separated electrons and holes, and stored in QW and QDs respectively. Storage and retrieval of photonic signals are verified by time-resolved photoluminescence experiments. A storage time in excess of 100 ms has been obtained at a temperature of 10 K while the switching speed reaches the order of ten megahertz.

  1. The effects of geometrical configurations on the head collision on nonlinear solitary pulses in a quantum semiconductor plasma: A case study on GaAs semiconductor

    Science.gov (United States)

    EL-Shamy, E. F.; Gohman, F. S.; Alqahtani, M. M.; AlFaify, S.

    2018-01-01

    An investigation is presented to examine nonlinear electrostatic waves in a quantum semiconductor plasma. A quantum semiconductor plasma model consisting of electrons and holes is going to be used, which includes exchange-correlation potentials, the quantum recoil effect, and degenerate pressures of electrons and holes. Actually, a nonlinear solitary pulse can be used to represent the intrinsic coherent electrostatic wave in a quantum semiconductor plasma. The propagation and the collision of nonlinear solitary pulses are examined by the extended Poincaré-Lighthill-Kuo method. Typical values for the GaAs semiconductors are employed to investigate the basic characteristics of solitary pulses. The numerical studies show that the energies and then the trajectories of nonlinear solitary pulses after the collision are significantly changed due to the effects of the exchange and correlation potentials and the variety in the studied system's geometry. The results obtained here may be useful for gaining a better understanding of the basic features of the nonlinear solitary pulses in quantum semiconductor plasmas.

  2. Low threshold amplified spontaneous emission from tin oxide quantum dots: a instantiation of dipole transition silence semiconductors.

    Science.gov (United States)

    Pan, Shu Sheng; Yu, Siu Fung; Zhang, Wen Fei; Zhu, Hai; Lu, Wei; Jin, Li Min

    2013-12-07

    Direct bandgap semiconductors, such as In2O3, Cu2O, and SnO2, have enormous applications in photochemistry, photovoltaics, and optoelectronics. Due to the same parity of conduction and valence bands, the dipole transition is silent in these direct bandgap semiconductors. The low band-to-band transition efficiency prevents them from high intensity light emission or absorption. Here, we report the fabrication of SnO2 quantum dots (QDs) with sizes less than the exciton Bohr radius by a facile "top-down" strategy based on laser fragmentation of SnO in water. The SnO2 QDs shows exciton emission at ∼300 nm with a high quantum yield of ~17%. Amplified spontaneous exciton emission is also achieved from a thin layer of SnO2 QDs dispersed in PEG400 on a quartz substrate. Therefore, we have shown that SnO2 QDs can be a potential luminescent material suitable for the realization of ultraviolet B lasing devices.

  3. Photo-Induced Spin Dynamics in Semiconductor Quantum Wells.

    Science.gov (United States)

    Miah, M Idrish

    2009-01-17

    We experimentally investigate the dynamics of spins in GaAs quantum wells under applied electric bias by photoluminescence (PL) measurements excited with circularly polarized light. The bias-dependent circular polarization of PL (P(PL)) with and without magnetic field is studied. The P(PL) without magnetic field is found to be decayed with an enhancement of increasing the strength of the negative bias. However, P(PL) in a transverse magnetic field shows oscillations under an electric bias, indicating that the precession of electron spin occurs in quantum wells. The results are discussed based on the electron-hole exchange interaction in the electric field.

  4. Photo-Induced Spin Dynamics in Semiconductor Quantum Wells

    Directory of Open Access Journals (Sweden)

    Miah M

    2009-01-01

    Full Text Available Abstract We experimentally investigate the dynamics of spins in GaAs quantum wells under applied electric bias by photoluminescence (PL measurements excited with circularly polarized light. The bias-dependent circular polarization of PL (P PL with and without magnetic field is studied. TheP PLwithout magnetic field is found to be decayed with an enhancement of increasing the strength of the negative bias. However,P PLin a transverse magnetic field shows oscillations under an electric bias, indicating that the precession of electron spin occurs in quantum wells. The results are discussed based on the electron–hole exchange interaction in the electric field.

  5. A triple quantum dot based nano-electromechanical memory device

    International Nuclear Information System (INIS)

    Pozner, R.; Lifshitz, E.; Peskin, U.

    2015-01-01

    Colloidal quantum dots (CQDs) are free-standing nano-structures with chemically tunable electronic properties. This tunability offers intriguing possibilities for nano-electromechanical devices. In this work, we consider a nano-electromechanical nonvolatile memory (NVM) device incorporating a triple quantum dot (TQD) cluster. The device operation is based on a bias induced motion of a floating quantum dot (FQD) located between two bound quantum dots (BQDs). The mechanical motion is used for switching between two stable states, “ON” and “OFF” states, where ligand-mediated effective interdot forces between the BQDs and the FQD serve to hold the FQD in each stable position under zero bias. Considering realistic microscopic parameters, our quantum-classical theoretical treatment of the TQD reveals the characteristics of the NVM

  6. Spatially correlated two-dimensional arrays of semiconductor and metal quantum dots in GaAs-based heterostructures

    Energy Technology Data Exchange (ETDEWEB)

    Nevedomskiy, V. N., E-mail: nevedom@mail.ioffe.ru; Bert, N. A.; Chaldyshev, V. V. [Russian Academy of Sciences, Ioffe Physical–Technical Institute (Russian Federation); Preobrazhernskiy, V. V.; Putyato, M. A.; Semyagin, B. R. [Russian Academy of Sciences, Institute of Semiconductor Physics, Siberian Branch (Russian Federation)

    2015-12-15

    A single molecular-beam epitaxy process is used to produce GaAs-based heterostructures containing two-dimensional arrays of InAs semiconductor quantum dots and AsSb metal quantum dots. The twodimensional array of AsSb metal quantum dots is formed by low-temperature epitaxy which provides a large excess of arsenic in the epitaxial GaAs layer. During the growth of subsequent layers at a higher temperature, excess arsenic forms nanoinclusions, i.e., metal quantum dots in the GaAs matrix. The two-dimensional array of such metal quantum dots is created by the δ doping of a low-temperature GaAs layer with antimony which serves as a precursor for the heterogeneous nucleation of metal quantum dots and accumulates in them with the formation of AsSb metal alloy. The two-dimensional array of InAs semiconductor quantum dots is formed via the Stranski–Krastanov mechanism at the GaAs surface. Between the arrays of metal and semiconductor quantum dots, a 3-nm-thick AlAs barrier layer is grown. The total spacing between the arrays of metal and semiconductor quantum dots is 10 nm. Electron microscopy of the structure shows that the arrangement of metal quantum dots and semiconductor quantum dots in the two-dimensional arrays is spatially correlated. The spatial correlation is apparently caused by elastic strain and stress fields produced by both AsSb metal and InAs semiconductor quantum dots in the GaAs matrix.

  7. Spatially correlated two-dimensional arrays of semiconductor and metal quantum dots in GaAs-based heterostructures

    International Nuclear Information System (INIS)

    Nevedomskiy, V. N.; Bert, N. A.; Chaldyshev, V. V.; Preobrazhernskiy, V. V.; Putyato, M. A.; Semyagin, B. R.

    2015-01-01

    A single molecular-beam epitaxy process is used to produce GaAs-based heterostructures containing two-dimensional arrays of InAs semiconductor quantum dots and AsSb metal quantum dots. The twodimensional array of AsSb metal quantum dots is formed by low-temperature epitaxy which provides a large excess of arsenic in the epitaxial GaAs layer. During the growth of subsequent layers at a higher temperature, excess arsenic forms nanoinclusions, i.e., metal quantum dots in the GaAs matrix. The two-dimensional array of such metal quantum dots is created by the δ doping of a low-temperature GaAs layer with antimony which serves as a precursor for the heterogeneous nucleation of metal quantum dots and accumulates in them with the formation of AsSb metal alloy. The two-dimensional array of InAs semiconductor quantum dots is formed via the Stranski–Krastanov mechanism at the GaAs surface. Between the arrays of metal and semiconductor quantum dots, a 3-nm-thick AlAs barrier layer is grown. The total spacing between the arrays of metal and semiconductor quantum dots is 10 nm. Electron microscopy of the structure shows that the arrangement of metal quantum dots and semiconductor quantum dots in the two-dimensional arrays is spatially correlated. The spatial correlation is apparently caused by elastic strain and stress fields produced by both AsSb metal and InAs semiconductor quantum dots in the GaAs matrix

  8. Semiconductor Quantum Dot Structures for Integrated Optic Switches

    Science.gov (United States)

    2008-12-23

    quantum boxes. These pillars are extremely fragile at this stage and are set in place by placing a drop of BCB and spinning off the excess. After the... BCB has been cured, the top surface is cleaned off of the BCB using reactive ion etching. Another photolithographic stage is performed to delineate

  9. Bandgap Engineering of 1300 nm Quantum Dots/Quantum Well Nanostructures Based Devices

    KAUST Repository

    Alhashim, Hala H.

    2016-05-29

    The main objectives of this thesis are to develop viable process and/or device technologies for bandgap tuning of 1300-nm InGaAs/GaAs quantum-dot (QD) laser structures, and broad linewidth 1300-nm InGaAsP/InP quantum well (QW) superluminescent diode structures. The high performance bandgap-engineered QD laser structures were achieved by employing quantum-dot intermixing (QDI) based on impurity free vacancy diffusion (IFVD) technique for eventual seamless active-passive integration, and bandgap-tuned lasers. QDI using various dielectric-capping materials, such as HfO2, SrTiO3, TiO2, Al2O3 and ZnO, etc, were experimented in which the resultant emission wavelength can be blueshifted to ∼ 1100 nm ─ 1200 nm range depending on process conditions. The significant results extracted from the PL characterization were used to perform an extensive laser characterization. The InAs/GaAs quantum-dot lasers with QDs transition energies were blueshifted by ~185 nm, and lasing around ~1070 – 1190 nm was achieved. Furthermore, from the spectral analysis, a simultaneous five-state lasing in the InAs/InGaAs intermixed QD laser was experimentally demonstrated for the first time in the very important wavelength range from 1030 to 1125 nm. The QDI methodology enabled the facile formation of a plethora of devices with various emission wavelengths suitable for a wide range of applications in the infrared. In addition, the wavelength range achieved is also applicable for coherent light generation in the green – yellow – orange visible wavelength band via frequency doubling, which is a cost-effective way of producing compact devices for pico-projectors, semiconductor laser based solid state lighting, etc. [1, 2] In QW-based superluminescent diode, the problem statement lies on achieving a flat-top and ultra-wide emission bandwidth. The approach was to design an inhomogeneous active region with a comparable simultaneous emission from different transition states in the QW stacks, in

  10. Quantum theory of the electronic and optical properties of low-dimensional semiconductor systems

    Science.gov (United States)

    Lau, Wayne Heung

    This thesis examines the electronic and optical properties of low-dimensional semiconductor systems. A theory is developed to study the electron-hole generation-recombination process of type-II semimetallic semiconductor heterojunctions based on a 3 x 3 k·p matrix Hamiltonian (three-band model) and an 8 x 8 k·p matrix Hamiltonian (eight-band model). A novel electron-hole generation and recombination process, which is called activationless generation-recombination process, is predicted. It is demonstrated that the current through the type-II semimetallic semiconductor heterojunctions is governed by the activationless electron-hole generation-recombination process at the heterointerfaces, and that the current-voltage characteristics are essentially linear. A qualitative agreement between theory and experiments is observed. The numerical results of the eight-band model are compared with those of the threeband model. Based on a lattice gas model, a theory is developed to study the influence of a random potential on the ionization equilibrium conditions for bound electron-hole pairs (excitons) in III--V semiconductor heterostructures. It is demonstrated that ionization equilibrium conditions for bound electron-hole pairs change drastically in the presence of strong disorder. It is predicted that strong disorder promotes dissociation of excitons in III--V semiconductor heterostructures. A theory of polariton (photon dressed by phonon) spontaneous emission in a III--V semiconductor doped with semiconductor quantum dots (QDs) or quantum wells (QWs) is developed. For the first time, superradiant and subradiant polariton spontaneous emission phenomena in a polariton-QD (QW) coupled system are predicted when the resonance energies of the two identical QDs (QWs) lie outside the polaritonic energy gap. It is also predicted that when the resonance energies of the two identical QDs (QWs) lie inside the polaritonic energy gap, spontaneous emission of polariton in the polariton

  11. 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...

  12. Nano-Bio Quantum Technology for Device-Specific Materials

    Science.gov (United States)

    Choi, Sang H.

    2009-01-01

    The areas discussed are still under development: I. Nano structured materials for TE applications a) SiGe and Be.Te; b) Nano particles and nanoshells. II. Quantum technology for optical devices: a) Quantum apertures; b) Smart optical materials; c) Micro spectrometer. III. Bio-template oriented materials: a) Bionanobattery; b) Bio-fuel cells; c) Energetic materials.

  13. Layer-by-layer assembly of multicolored semiconductor quantum dots towards efficient blue, green, red and full color optical films

    International Nuclear Information System (INIS)

    Zhang Jun; Li Qian; Di Xiaowei; Liu Zhiliang; Xu Gang

    2008-01-01

    Multicolored semiconductor quantum dots have shown great promise for construction of miniaturized light-emitting diodes with compact size, low weight and cost, and high luminescent efficiency. The unique size-dependent luminescent property of quantum dots offers the feasibility of constructing single-color or full-color output light-emitting diodes with one type of material. In this paper, we have demonstrated the facile fabrication of blue-, green-, red- and full-color-emitting semiconductor quantum dot optical films via a layer-by-layer assembly technique. The optical films were constructed by alternative deposition of different colored quantum dots with a series of oppositely charged species, in particular, the new use of cationic starch on glass substrates. Semiconductor ZnSe quantum dots exhibiting blue emission were deposited for fabrication of blue-emitting optical films, while semiconductor CdTe quantum dots with green and red emission were utilized for construction of green- and red-emitting optical films. The assembly of integrated blue, green and red semiconductor quantum dots resulted in full-color-emitting optical films. The luminescent optical films showed very bright emitting colors under UV irradiation, and displayed dense, smooth and efficient luminous features, showing brighter luminescence in comparison with their corresponding quantum dot aqueous colloid solutions. The assembled optical films provide the prospect of miniaturized light-emitting-diode applications.

  14. Metal/Semiconductor and Transparent Conductor/Semiconductor Heterojunctions in High Efficient Photoelectric Devices: Progress and Features

    Directory of Open Access Journals (Sweden)

    M. Melvin David Kumar

    2014-01-01

    Full Text Available Metal/semiconductor and transparent conductive oxide (TCO/semiconductor heterojunctions have emerged as an effective modality in the fabrication of photoelectric devices. This review is following a recent shift toward the engineering of TCO layers and structured Si substrates, incorporating metal nanoparticles for the development of next-generation photoelectric devices. Beneficial progress which helps to increase the efficiency and reduce the cost, has been sequenced based on efficient technologies involved in making novel substrates, TCO layers, and electrodes. The electrical and optical properties of indium tin oxide (ITO and aluminum doped zinc oxide (AZO thin films can be enhanced by structuring the surface of TCO layers. The TCO layers embedded with Ag nanoparticles are used to enhance the plasmonic light trapping effect in order to increase the energy harvesting nature of photoelectric devices. Si nanopillar structures which are fabricated by photolithography-free technique are used to increase light-active surface region. The importance of the structure and area of front electrodes and the effect of temperature at the junction are the value added discussions in this review.

  15. Spin dynamics of an individual Cr atom in a semiconductor quantum dot under optical excitation

    Energy Technology Data Exchange (ETDEWEB)

    Lafuente-Sampietro, A. [Université Grenoble Alpes, Institut Néel, F-38000 Grenoble (France); CNRS, Institut Néel, F-38000 Grenoble (France); Institute of Materials Science, University of Tsukuba, 305-8573 Tsukuba (Japan); Utsumi, H.; Kuroda, S. [Institute of Materials Science, University of Tsukuba, 305-8573 Tsukuba (Japan); Boukari, H.; Besombes, L., E-mail: lucien.besombes@grenoble.cnrs.fr [Université Grenoble Alpes, Institut Néel, F-38000 Grenoble (France); CNRS, Institut Néel, F-38000 Grenoble (France)

    2016-08-01

    We studied the spin dynamics of a Cr atom incorporated in a II-VI semiconductor quantum dot using photon correlation techniques. We used recently developed singly Cr-doped CdTe/ZnTe quantum dots to access the spin of an individual magnetic atom. Auto-correlation of the photons emitted by the quantum dot under continuous wave optical excitation reveals fluctuations of the localized spin with a timescale in the 10 ns range. Cross-correlation gives quantitative transfer time between Cr spin states. A calculation of the time dependence of the spin levels population in Cr-doped quantum dots shows that the observed spin dynamics is dominated by the exciton-Cr interaction. These measurements also provide a lower bound in the 20 ns range for the intrinsic Cr spin relaxation time.

  16. Light Emission and Energy Transfer in Nanoscale Semiconductor Photonic Devices

    National Research Council Canada - National Science Library

    Kolbas, Robert

    1997-01-01

    .... The proposed research impacts device development and system architectures by demonstrating light emitters for wavelength division multiplexing, three dimensional IOEC structures, broadly tunable...

  17. Ultrahigh-frequency microwave phase shifts mediated by ultrafast dynamics in quantum-dot semiconductor optical amplifiers

    DEFF Research Database (Denmark)

    Chen, Yaohui; Mørk, Jesper

    2010-01-01

    We present a novel scheme to achieve tunable microwave phase shifts at frequencies exceeding 100 GHz based on wavelength conversion induced by high-speed cross-gain modulation in quantum-dot semiconductor optical amplifiers.......We present a novel scheme to achieve tunable microwave phase shifts at frequencies exceeding 100 GHz based on wavelength conversion induced by high-speed cross-gain modulation in quantum-dot semiconductor optical amplifiers....

  18. Tests and Analysis of Electromagnetic Models for Semiconductor-Metal Quantum-Well Lasers

    Science.gov (United States)

    Shih, Meng-Mu

    2012-03-01

    This work tests the proposed electromagnetic models for quantum-well lasers by using several materials of semiconductors and metals. Different combinations of semiconductors and metals can generate various wavelengths and mode-couplings in such semiconductor waveguide structures with built-in metal-gratings. The numerical results of these models are computed by the photonic approach and verified by the optical approach. Even for the weak mode-coupling cases, the numerical results computed by both approaches have close values. Numerical results with post-analysis can summarize how the key parameters, such as grating geometry, well thickness, and layer thickness, affect the mode-couplings. The above results can be further interpreted by physics intuition and fundamental concepts so as to provide insights into the modeling and design of lasers for more applications.

  19. Nanoscale semiconductor hybrids: fundamental physics and advanced devices

    Energy Technology Data Exchange (ETDEWEB)

    Nguyen, Binh-Minh [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2014-04-09

    Key summary: Low dimensional hybrids: more flexibility and better controllability of materials properties. Type-II Antimonide-based superlattice: system of interacting quantum wells, for infrared detection and imaging. Hetero-designs in core/multi-shell nanowires: promising candidate for high performance electronic and sensing applications. An interdisciplinary research plan could trigger interest and collaboration within RIT.

  20. Potential energy surface of excited semiconductors: Graphene quantum dot and BODIPY

    Energy Technology Data Exchange (ETDEWEB)

    Colherinhas, Guilherme [Departamento de Física-CEPAE, Universidade Federal de Goiás, 74690-900 Goiânia (Brazil); Fileti, Eudes Eterno [Instituto de Ciência e Tecnologia, Universidade Federal de São Paulo, 12231-280 São José dos Campos, SP (Brazil); Chaban, Vitaly V., E-mail: vvchaban@gmail.com [Instituto de Ciência e Tecnologia, Universidade Federal de São Paulo, 12231-280 São José dos Campos, SP (Brazil)

    2016-08-02

    Graphical abstract: Excitation of graphene quantum dot significantly alters its interaction with water. - Abstract: Binding energy (BE) is an important descriptor in chemistry, which determines thermodynamics and phase behavior of a given substance. BE between two molecules is not directly accessible from the experiment. It has to be reconstructed from cohesive energies, vaporization heats, etc. We report BE for the excited states of two semiconductor molecules – boron-dipyrromethene (BODIPY) and graphene quantum dot (GQD) – with water. We show, for the first time, that excitation increases BE twofold at an optimal separation (energy minimum position), whereas higher separations lead to higher differences. Interestingly, the effects of excitation are similar irrespective of the dominant binding interactions (van der Waals or electrostatic) in the complex. This new knowledge is important for simulations of the excited semiconductors by simplified interaction functions.

  1. Electron-electron scattering and mobilities in semiconductors and quantum wells

    International Nuclear Information System (INIS)

    Lyo, S.K.

    1986-01-01

    The effect of electron-electron scattering on the mobility in semiconductors and semiconductor quantum wells is examined. A general exact formula is derived for the mobility, when the electron-electron collision rate is much faster than other scattering rates such as those by ionized impurities and phonons. In this limit, the transport relaxation rate is independent of the carrier's energy and contributions to the inverse mobility from individual scattering mechanism add up. The mobility becomes significantly reduced from its value in the absence of electron-electron scattering. When the collision rates are not necessarily dominated by electron-electron scattering, the mobility is calculated by the Kohler-Sondheimer variational method in the presence of ionized-impurity scattering and acoustic-phonon scattering in a nondegenerate two-dimensional quantum well

  2. Advanced Semiconductor Heterostructures Novel Devices, Potential Device Applications and Basic Properties

    CERN Document Server

    Stroscio, Michael A

    2003-01-01

    This volume provides valuable summaries on many aspects of advanced semiconductor heterostructures and highlights the great variety of semiconductor heterostructures that has emerged since their original conception. As exemplified by the chapters in this book, recent progress on advanced semiconductor heterostructures spans a truly remarkable range of scientific fields with an associated diversity of applications. Some of these applications will undoubtedly revolutionize critically important facets of modern technology. At the heart of these advances is the ability to design and control the pr

  3. Practical device-independent quantum cryptography via entropy accumulation.

    Science.gov (United States)

    Arnon-Friedman, Rotem; Dupuis, Frédéric; Fawzi, Omar; Renner, Renato; Vidick, Thomas

    2018-01-31

    Device-independent cryptography goes beyond conventional quantum cryptography by providing security that holds independently of the quality of the underlying physical devices. Device-independent protocols are based on the quantum phenomena of non-locality and the violation of Bell inequalities. This high level of security could so far only be established under conditions which are not achievable experimentally. Here we present a property of entropy, termed "entropy accumulation", which asserts that the total amount of entropy of a large system is the sum of its parts. We use this property to prove the security of cryptographic protocols, including device-independent quantum key distribution, while achieving essentially optimal parameters. Recent experimental progress, which enabled loophole-free Bell tests, suggests that the achieved parameters are technologically accessible. Our work hence provides the theoretical groundwork for experimental demonstrations of device-independent cryptography.

  4. Periodic dark pulse emission induced by delayed feedback in a quantum well semiconductor laser

    Directory of Open Access Journals (Sweden)

    L. Li

    2012-12-01

    Full Text Available We report the experimental observation of periodic dark pulse emission in a quantum-well semiconductor laser with delayed optical feedback. We found that under appropriate operation conditions the laser can also emit a stable train of dark pulses. The repetition frequency of the dark pulse is determined by the external cavity length. Splitting of the dark pulse was also observed. We speculate that the observed dark pulse is a kind of temporal cavity soliton formed in the laser.

  5. Space-charge solitary waves and double layers in n-type compensated semiconductor quantum plasma

    Science.gov (United States)

    Banerjee, S.; Ghosh, B.

    2018-03-01

    Using quantum hydrodynamic (QHD) model and standard reductive perturbation method, we have investigated the formation and characteristics of space-charge solitary waves and double layers in n-type compensated drifting semiconductor plasma with varying doping profiles. Through numerical analysis, it is shown that the structures of space-charge solitary waves and double layers depend significantly on electron drift and compensation parameter which measures a comparative proportion of the donor, acceptor and intrinsic ion concentrations.

  6. Effect of intravalley acoustic phonon scattering on quantum transport in multigate silicon nanowire metal-oxide-semiconductor field-effect transistors

    Science.gov (United States)

    Akhavan, Nima Dehdashti; Afzalian, Aryan; Lee, Chi-Woo; Yan, Ran; Ferain, Isabelle; Razavi, Pedram; Yu, Ran; Fagas, Giorgos; Colinge, Jean-Pierre

    2010-08-01

    In this paper we investigate the effects of intravalley acoustic phonon scattering on the quantum transport and on the electrical characteristics of multigate silicon nanowire metal-oxide-semiconductor field-effect transistors. We show that acoustic phonons cause a shift and broadening of the local DOS in the nanowire, which modifies the electrical characteristics of the device. The influence of scattering on off-state and on-state currents is investigated for different values of channel length. In the ballistic transport regime, source-to-drain tunneling current is predominant, whereas in the presence of acoustic phonons, diffusion becomes the dominant current transport mechanism. A three-dimensional quantum mechanical device simulator based on the nonequilibrium Green's function formalism in uncoupled-mode space has been developed to extract device parameters in the presence of electron-phonon interactions. Electron-phonon scattering is accounted for by adopting the self-consistent Born approximation and using the deformation potential theory.

  7. Low contact resistance in epitaxial graphene devices for quantum metrology

    Energy Technology Data Exchange (ETDEWEB)

    Yager, Tom, E-mail: yager@chalmers.se, E-mail: ywpark@snu.ac.kr; Lartsev, Arseniy; Lara-Avila, Samuel; Kubatkin, Sergey [Department of Microtechnology and Nanoscience, Chalmers University of Technology Göteborg, S-412 96 (Sweden); Cedergren, Karin [School of Physics, University of New South Wales, Sydney, NSW-2052 (Australia); Yakimova, Rositsa [Department of Physics, Chemistry and Biology (IFM), Linköping University Linköping, S-581 83 (Sweden); Panchal, Vishal; Kazakova, Olga [National Physical Laboratory, Teddington, TW11 0LW (United Kingdom); Tzalenchuk, Alexander [National Physical Laboratory, Teddington, TW11 0LW (United Kingdom); Department of Physics, Royal Holloway, University of London, Egham, TW20 0EX (United Kingdom); Kim, Kyung Ho; Park, Yung Woo, E-mail: yager@chalmers.se, E-mail: ywpark@snu.ac.kr [Department of Physics and Astronomy, Seoul National University, Seoul 151-747 (Korea, Republic of)

    2015-08-15

    We investigate Ti/Au contacts to monolayer epitaxial graphene on SiC (0001) for applications in quantum resistance metrology. Using three-terminal measurements in the quantum Hall regime we observed variations in contact resistances ranging from a minimal value of 0.6 Ω up to 11 kΩ. We identify a major source of high-resistance contacts to be due bilayer graphene interruptions to the quantum Hall current, whilst discarding the effects of interface cleanliness and contact geometry for our fabricated devices. Moreover, we experimentally demonstrate methods to improve the reproducibility of low resistance contacts (<10 Ω) suitable for high precision quantum resistance metrology.

  8. Low contact resistance in epitaxial graphene devices for quantum metrology

    Directory of Open Access Journals (Sweden)

    Tom Yager

    2015-08-01

    Full Text Available We investigate Ti/Au contacts to monolayer epitaxial graphene on SiC (0001 for applications in quantum resistance metrology. Using three-terminal measurements in the quantum Hall regime we observed variations in contact resistances ranging from a minimal value of 0.6 Ω up to 11 kΩ. We identify a major source of high-resistance contacts to be due bilayer graphene interruptions to the quantum Hall current, whilst discarding the effects of interface cleanliness and contact geometry for our fabricated devices. Moreover, we experimentally demonstrate methods to improve the reproducibility of low resistance contacts (<10 Ω suitable for high precision quantum resistance metrology.

  9. 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...

  10. A measurement system for the photoelectric and electrical characterization of modern semiconductor devices

    Science.gov (United States)

    Piskorski, K.; Niemiec, M.; Borowicz, L.; Przewlocki, H. M.

    2017-05-01

    In this article a universal system for photoelectric measurements (USPM) is described, with several subsystems allowing comprehensive characterization of various semiconductor devices, primarily MOS (metal-oxide-semiconductor) structures. MOS structures are fundamental components of all modern integrated circuits and the key parameters of these structures can be determined by several electrical and photoelectric techniques. In particular, photoelectric investigations are very important and useful in the characterization of micro- and nanoelectronic semiconductor devices since they offer very accurate and reproducible measurements of important electric parameters, e.g. barrier heights on interfaces of multilayered structures. In the case of integrated circuits with structures of nm aerial dimensions, photoelectric measurements have to be made on test structures with larger aerial dimensions, accompanying the integrated circuits, since the minimum diameter of the light beam used is in the range of micrometers. The USPM system has been designed and built in our laboratory and allows very precise and sensitive measurements to be taken.

  11. Quantum Dot Semiconductor Optical Amplifiers - Physics and Applications

    DEFF Research Database (Denmark)

    Berg, Tommy Winther

    2004-01-01

    respects is comparable to those of fiber amplifiers. The possibility of inverting the optically active states to a large degree is essential in order to achieve this performance. Optical signal processing through cross gain modulation and four wave mixing is modeled and described. For both approaches...... quantum dot amplifiers are found to be able to operate with high efficiency and at high bitrates. Strong spectral hole-burning arising from a relatively slow carrier capture time, is shown to play a dominant role is this context. The results obtained numerically are compared to the properties of bulk...

  12. Second-harmonic scanning optical microscopy of semiconductor quantum dots

    DEFF Research Database (Denmark)

    Vohnsen, B.; Bozhevolnyi, S.I.; Pedersen, K.

    2001-01-01

    Second-harmonic (SH) optical imaging of self-assembled InAlGaAs quantum dots (QD's) grown on a GaAs(0 0 1) substrate has been accomplished at room temperature by use of respectively a scanning far-field optical microscope in reflection mode and a scanning near-field optical microscope...... in transmission mode. In both cases the SH signal peaks at a pump wavelength of similar to 885 nm in correspondence to the maximum in the photoluminescence spectrum of the QD sample. SH near-field optical images exhibit spatial signal variations on a subwavelength scale that depend on the pump wavelength. We...

  13. Ordered Dissipative Structures in Exciton Systems in Semiconductor Quantum Wells

    Directory of Open Access Journals (Sweden)

    Andrey A. Chernyuk

    2006-02-01

    Full Text Available A phenomenological theory of exciton condensation in conditions of inhomogeneous excitation is proposed. The theory is applied to the study of the development of an exciton luminescence ring and the ring fragmentation at macroscopical distances from the central excitation spot in coupled quantum wells. The transition between the fragmented and the continuous ring is considered. With assumption of a defect in the structure, a possibility of a localized island of the condensed phase in a fixed position is shown. Exciton density distribution is also analyzed in the case of two spatially separated spots of the laser excitation.

  14. Second-harmonic scanning optical microscopy of semiconductor quantum dots

    DEFF Research Database (Denmark)

    Vohnsen, B.; Bozhevolnyi, S.I.; Pedersen, K.

    2001-01-01

    in transmission mode. In both cases the SH signal peaks at a pump wavelength of similar to 885 nm in correspondence to the maximum in the photoluminescence spectrum of the QD sample. SH near-field optical images exhibit spatial signal variations on a subwavelength scale that depend on the pump wavelength. We......Second-harmonic (SH) optical imaging of self-assembled InAlGaAs quantum dots (QD's) grown on a GaAs(0 0 1) substrate has been accomplished at room temperature by use of respectively a scanning far-field optical microscope in reflection mode and a scanning near-field optical microscope...

  15. Long coherence times in self-assembled semiconductor quantum dots

    DEFF Research Database (Denmark)

    Birkedal, Dan; Leosson, K.; Hvam, Jørn Märcher

    2002-01-01

    We report measurements of ultra-long coherence in self-assembled quantum dots. Transient four-wave mixing experiments at 5 K show an average dephasing time of 372 ps, corresponding to a homogeneous linewidth of 3.5 mueV, which is significantly smaller than the linewidth observed in single-dot...... luminescence. Time-resolved luminescence measurements show a lifetime of the dot ground state of 800 ps demonstrating the presence of pure dephasing at finite temperature. The homogeneous width is lifetime limited only at temperatures approaching 0 K....

  16. On-Chip Quantum-Dot Light Source for Quantum-Device Readout

    Science.gov (United States)

    Liu, Y.-Y.; Stehlik, J.; Mi, X.; Hartke, T. R.; Gullans, M. J.; Petta, J. R.

    2018-01-01

    We use microwave radiation generated by a semiconductor double-quantum-dot (DQD) micromaser for charge-state detection. A cavity is populated with nc˜6000 photons by driving a current through an emitter DQD. These photons are used to sense the charge state of a target DQD that is located at the opposite end of the cavity. The charge dynamics in the target DQD influences the output power and emission frequency of the maser. Three different readout mechanisms are compared. The detection scheme requires no cavity input field and may potentially be used to improve the scalability of semiconductor and superconducting qubit readout technologies.

  17. Interface Design Principles for High-Performance Organic Semiconductor Devices.

    Science.gov (United States)

    Nie, Wanyi; Gupta, Gautam; Crone, Brian K; Liu, Feilong; Smith, Darryl L; Ruden, P Paul; Kuo, Cheng-Yu; Tsai, Hsinhan; Wang, Hsing-Lin; Li, Hao; Tretiak, Sergei; Mohite, Aditya D

    2015-06-01

    Precise manipulation of organic donor-acceptor interfaces using spacer layers is demonstrated to suppress interface recombination in an organic photo-voltaic device. These strategies lead to a dramatic improvement in a model bilayer system and bulk-heterojunction system. These interface strategies are applicable to a wide variety of donor-acceptor systems, making them both fundamentally interesting and technologically relevant for achieving high efficiency organic electronic devices.

  18. Off-axis electron holography for the measurement of active dopants in silicon semiconductor devices

    International Nuclear Information System (INIS)

    Cooper, David

    2016-01-01

    There is a need in the semiconductor industry for a dopant profiling technique with nm-scale resolution. Here we demonstrate that off-axis electron holography can be used to provide maps of the electrostatic potential in semiconductor devices with nm-scale resolution. In this paper we will discuss issues regarding the spatial resolution and precision of the technique. Then we will discuss problems with specimen preparation and how this affects the accuracy of the measurements of the potentials. Finally we show results from experimental off-axis electron holography applied to nMOS and pMOS CMOS devices grown on bulk silicon and silicon- on-insulator type devices and present solutions to common problems that are encountered when examining these types of devices. (paper)

  19. Single-electron regime and Pauli spin blockade in a silicon metal-oxide-semiconductor double quantum dot

    Science.gov (United States)

    Rochette, Sophie; Ten Eyck, Gregory A.; Pluym, Tammy; Lilly, Michael P.; Carroll, Malcolm S.; Pioro-Ladrière, Michel

    2015-03-01

    Silicon quantum dots are promising candidates for quantum information processing as spin qubits with long coherence time. We present electrical transport measurements on a silicon metal-oxide-semiconductor (MOS) double quantum dot (DQD). First, Coulomb diamonds measurements demonstrate the one-electron regime at a relatively high temperature of 1.5 K. Then, the 8 mK stability diagram shows Pauli spin blockade with a large singlet-triplet separation of approximatively 0.40 meV, pointing towards a strong lifting of the valley degeneracy. Finally, numerical simulations indicate that by integrating a micro-magnet to those devices, we could achieve fast spin rotations of the order of 30 ns. Those results are part of the recent body of work demonstrating the potential of Si MOS DQD as reliable and long-lived spin qubits that could be ultimately integrated into modern electronic facilities. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. DOE's National Nuclear Security Administration under Contract DE-AC04-94AL85000.

  20. Resonance fluorescence and electron spin in semiconductor quantum dots

    International Nuclear Information System (INIS)

    Zhao, Yong

    2009-01-01

    The work presented in this dissertation contains the first observation of spin-resolved resonance fluorescence from a single quantum dot and its application of direct measurement of electron spin dynamics. The Mollow triplet and the Mollow quintuplet, which are the hallmarks of resonance fluorescence, are presented as the non-spin-resolved and spin-resolved resonance fluorescence spectrum, respectively. The negligible laser background contribution, the near pure radiative broadened spectrum and the anti-bunching photon statistics imply the sideband photons are background-free and near transform-limited single photons. This demonstration is a promising step towards the heralded single photon generation and electron spin readout. Instead of resolving spectrum, an alternative spin-readout scheme by counting resonance fluorescence photons under moderate laser power is demonstrated. The measurements of n-shot time-resolved resonance fluorescence readout are carried out to reveal electron spin dynamics of the measurement induced back action and the spin relaxation. Hyperfine interaction and heavy-light hole mixing are identified as the relevant mechanisms for the back action and phonon-assistant spin-orbit interaction dominates the spin relaxation. After a detailed discussion on charge-spin configurations in coupled quantum dots system, the single-shot readout on electron spin are proposed. (orig.)

  1. Resonance fluorescence and electron spin in semiconductor quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Yong

    2009-11-18

    The work presented in this dissertation contains the first observation of spin-resolved resonance fluorescence from a single quantum dot and its application of direct measurement of electron spin dynamics. The Mollow triplet and the Mollow quintuplet, which are the hallmarks of resonance fluorescence, are presented as the non-spin-resolved and spin-resolved resonance fluorescence spectrum, respectively. The negligible laser background contribution, the near pure radiative broadened spectrum and the anti-bunching photon statistics imply the sideband photons are background-free and near transform-limited single photons. This demonstration is a promising step towards the heralded single photon generation and electron spin readout. Instead of resolving spectrum, an alternative spin-readout scheme by counting resonance fluorescence photons under moderate laser power is demonstrated. The measurements of n-shot time-resolved resonance fluorescence readout are carried out to reveal electron spin dynamics of the measurement induced back action and the spin relaxation. Hyperfine interaction and heavy-light hole mixing are identified as the relevant mechanisms for the back action and phonon-assistant spin-orbit interaction dominates the spin relaxation. After a detailed discussion on charge-spin configurations in coupled quantum dots system, the single-shot readout on electron spin are proposed. (orig.)

  2. Proceedings of the 3rd international workshop on radiation effects on semiconductor devices for space application

    International Nuclear Information System (INIS)

    1998-10-01

    This publication is the collection of the paper presented at the title workshop. The main purpose of the workshop is to bring the chance for exchange of information between scientists and engineers who work in the field of research and development of semiconductor devices used in strong radiation environment in space. The 27 of the presented papers are indexed individually. (J.P.N.)

  3. Injection induced enhancement of supercurrent in a mesoscopic three terminal superconductor semiconductor device

    DEFF Research Database (Denmark)

    Kutchinsky, Jonatan; Taboryski, Rafael Jozef; Jensen, S

    2001-01-01

    The studied devices consist of three superconducting (Al) electrodes connected to the same piece of degenerate Semiconductor (n++ GaAs) in a planar geometry. When a current is injected from one of the superconducting electrodes at an injection bias V = Delta (T)/e, the critical supercurrent betwe...

  4. A variance-reduced electrothermal Monte Carlo method for semiconductor device simulation

    Energy Technology Data Exchange (ETDEWEB)

    Muscato, Orazio; Di Stefano, Vincenza [Univ. degli Studi di Catania (Italy). Dipt. di Matematica e Informatica; Wagner, Wolfgang [Weierstrass-Institut fuer Angewandte Analysis und Stochastik (WIAS) Leibniz-Institut im Forschungsverbund Berlin e.V., Berlin (Germany)

    2012-11-01

    This paper is concerned with electron transport and heat generation in semiconductor devices. An improved version of the electrothermal Monte Carlo method is presented. This modification has better approximation properties due to reduced statistical fluctuations. The corresponding transport equations are provided and results of numerical experiments are presented.

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

    KAUST Repository

    Wang, Zhenwei

    2016-02-16

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

  6. Development of heavy-ion irradiation technique for single-event in semiconductor devices

    Energy Technology Data Exchange (ETDEWEB)

    Nemoto, Norio; Akutsu, Takao; Matsuda, Sumio [National Space Development Agency of Japan, Tsukuba, Ibaraki (Japan). Tsukuba Space Center; Naitoh, Ichiro; Itoh, Hisayoshi; Agematsu, Takashi; Kamiya, Tomihiro; Nashiyama, Isamu

    1997-03-01

    Heavy-ion irradiation technique has been developed for the evaluation of single-event effects on semiconductor devices. For the uniform irradiation of high energy heavy ions to device samples, we have designed and installed a magnetic beam-scanning system in a JAERI cyclotron beam course. It was found that scanned area was approximately 4 x 2 centimeters and that the deviation of ion fluence from the average value was less than 7%. (author)

  7. Improvement of cosmic ray ruggedness of hybrid vehicles power semiconductor devices

    International Nuclear Information System (INIS)

    Nishida, Shuichi; Ohnishi, Toyokazu; Fujikawa, Touma; Nose, Noboru; Hamada, Kimimori; Shoji, Tomoyuki; Ishiko, Masayasu

    2010-01-01

    Power semiconductors which are used under high voltage conditions in HVs (Hybrid Vehicles) are required to have high destruction tolerance against cosmic rays as well as to meet conventional quality standards. In this paper, an SEB (Single Event Burnout) failure mechanism induced by cosmic rays in IGBTs (Insulated Gate Bipolar Transistors) was investigated. Through an optimized device design in which thyristor action was suppressed, the device destruction tolerance was greatly improved. (author)

  8. Fabrication of quantum-dot devices in graphene

    Directory of Open Access Journals (Sweden)

    Satoshi Moriyama, Yoshifumi Morita, Eiichiro Watanabe, Daiju Tsuya, Shinya Uji, Maki Shimizu and Koji Ishibashi

    2010-01-01

    Full Text Available We describe our recent experimental results on the fabrication of quantum-dot devices in a graphene-based two-dimensional system. Graphene samples were prepared by micromechanical cleavage of graphite crystals on a SiO2/Si substrate. We performed micro-Raman spectroscopy measurements to determine the number of layers of graphene flakes during the device fabrication process. By applying a nanofabrication process to the identified graphene flakes, we prepared a double-quantum-dot device structure comprising two lateral quantum dots coupled in series. Measurements of low-temperature electrical transport show the device to be a series-coupled double-dot system with varied interdot tunnel coupling, the strength of which changes continuously and non-monotonically as a function of gate voltage.

  9. High Density Memory Based on Quantum Device Technology

    Science.gov (United States)

    vanderWagt, Paul; Frazier, Gary; Tang, Hao

    1995-01-01

    We explore the feasibility of ultra-high density memory based on quantum devices. Starting from overall constraints on chip area, power consumption, access speed, and noise margin, we deduce boundaries on single cell parameters such as required operating voltage and standby current. Next, the possible role of quantum devices is examined. Since the most mature quantum device, the resonant tunneling diode (RTD) can easily be integrated vertically, it naturally leads to the issue of 3D integrated memory. We propose a novel method of addressing vertically integrated bistable two-terminal devices, such as resonant tunneling diodes (RTD) and Esaki diodes, that avoids individual physical contacts. The new concept has been demonstrated experimentally in memory cells of field effect transistors (FET's) and stacked RTD's.

  10. Monolithically integrated quantum dot optical modulator with semiconductor optical amplifier for thousand and original band optical communication

    Science.gov (United States)

    Yamamoto, Naokatsu; Akahane, Kouichi; Umezawa, Toshimasa; Matsumoto, Atsushi; Kawanishi, Tetsuya

    2016-04-01

    A monolithically integrated quantum dot (QD) optical gain modulator (OGM) with a QD semiconductor optical amplifier (SOA) was successfully developed with T-band (1.0 µm waveband) and O-band (1.3 µm waveband) QD optical gain materials for Gbps-order, high-speed optical data generation. The insertion loss due to coupling between the device and the optical fiber was effectively compensated for by the SOA section. It was also confirmed that the monolithic QD-OGM/SOA device enabled >4.8 Gbps optical data generation with a clear eye opening in the T-band. Furthermore, we successfully demonstrated error-free 4.8 Gbps optical data transmissions in each of the six wavelength channels over a 10-km-long photonic crystal fiber using the monolithic QD-OGM/SOA device in multiple O-band wavelength channels, which were generated by the single QD gain chip. These results suggest that the monolithic QD-OGM/SOA device will be advantageous in ultra-broadband optical frequency systems that utilize the T+O-band for short- and medium-range optical communications.

  11. Theory of semiconductor lasers from basis of quantum electronics to analyses of the mode competition phenomena and noise

    CERN Document Server

    Yamada, Minoru

    2014-01-01

    This book provides a unified and complete theory for semiconductor lasers, covering topics ranging from the principles of classical and quantum mechanics to highly advanced levels for readers who need to analyze the complicated operating characteristics generated in the real application of semiconductor lasers.   The author conducts a theoretical analysis especially on the instabilities involved in the operation of semiconductor lasers. A density matrix into the theory for semiconductor lasers is introduced and the formulation of an improved rate equation to help understand the mode competition phenomena which cause the optical external feedback noise is thoroughly described from the basic quantum mechanics. The derivation of the improved rate equation will allow readers to extend the analysis for the different types of semiconductor materials and laser structures they deal with.   This book is intended not only for students and academic researchers but also for engineers who develop lasers for the market, ...

  12. Quantum theory of terahertz conductivity of semiconductor nanostructures

    Science.gov (United States)

    Ostatnický, T.; Pushkarev, V.; Němec, H.; Kužel, P.

    2018-02-01

    Efficient and controlled charge carrier transport through nanoelements is currently a primordial question in the research of nanoelectronic materials and structures. We develop a quantum-mechanical theory of the conductivity spectra of confined charge carriers responding to an electric field from dc regime up to optical frequencies. The broken translation symmetry induces a broadband drift-diffusion current, which is not taken into account in the analysis based on Kubo formula and relaxation time approximation. We show that this current is required to ensure that the dc conductivity of isolated nanostructures correctly attains zero. It causes a significant reshaping of the conductivity spectra up to terahertz or multiterahertz spectral ranges, where the electron scattering rate is typically comparable to or larger than the probing frequency.

  13. Temperature and Dilatation Estimation for Modern Semiconductor Devices

    Directory of Open Access Journals (Sweden)

    Eric JOUBERT

    2015-01-01

    Full Text Available This paper presents a new approach for measuring physical variables on micro- electronic components. An optical system is used to simultaneously quantify the surface temperature of a component and its expansion. This double acquisition is realized by a Michelson interferometer coupled with a Charge Coupled Device (CCD line device. To validate this method, the temperature measurements were directly compared with the results obtained by an infrared camera and by a measurement of variation of I (V. The displacement measurements were compared with those obtained by a laser 3D vibrometer, whose physical principle is completely different. Consistent results were obtained regarding the different techniques.

  14. Optical Spectroscopy of Hybrid Semiconductor Quantum Dots and Metal Nanoparticles

    Science.gov (United States)

    2014-11-07

    vehicle head lights by replacing the filament bulbs for energy saving and lifetime, while the spectral purity is more important than the spectral...Dots for Hybrid Light Emitting Devices,” The 12th International Conference on Nano Science and Nano Technology, November 6-7, 2014, Mokpo, South Korea...of Personnel receiving masters degrees Names of personnel receiving PHDs Names of other research staff Inventions (DD882) Scientific Progress Please

  15. Optical determination of vacuum Rabi splitting in a semiconductor quantum dot induced by a metal nanoparticle.

    Science.gov (United States)

    He, Yong; Jiang, Cheng; Chen, Bin; Li, Jin-Jin; Zhu, Ka-Di

    2012-07-15

    We propose a theoretical scheme to determine the vacuum Rabi splitting in a single semiconductor quantum dot (SQD) induced by a metal nanoparticle (MNP). Based on cavity quantum electrodynamics, the exciton-plasmon interaction between the SQD and the MNP is considered while a strong pump laser and a weak probe laser are simultaneously presented. By decreasing the distance between them, we can increase the coupling strength. At resonance, thanks to the strong coupling, a vacuum Rabi splitting can be observed clearly in the probe absorption spectrum. The coupling strength can be obtained by measuring the vacuum Rabi splitting. This strong coupling is significant for the investigation of surface-plasmon-based quantum information processing.

  16. Phonon induced pure dephasing process of excitonic state in colloidal semiconductor quantum dots

    Science.gov (United States)

    Huang, Tongyun; Han, Peng; Wang, Xinke; Feng, Shengfei; Sun, Wenfeng; Ye, Jiasheng; Zhang, Yan

    2016-04-01

    We present a theoretical study on the pure dephasing process of colloidal semiconductor quantum dots induced by lattice vibrations using continuum model calculations. By solving the time dependent Liouville-von Neumann equation, we present the ultrafast Rabi oscillations between excitonic state and virtual state via exciton-phonon interaction and obtain the pure dephasing time from the fast decayed envelope of the Rabi oscillations. The interaction between exciton and longitudinal optical phonon vibration is found to dominate the pure dephasing process and the dephasing time increases nonlinearly with the reduction of exciton-phonon coupling strength. We further find that the pure dephasing time of large quantum dots is more sensitive to temperature than small quantum dots.

  17. Intrinsic normal Zeeman effect for spin plasmons in semiconductor quantum wells

    Science.gov (United States)

    Ullrich, C. A.; D'Amico, I.; Baboux, F.; Perez, F.

    2013-09-01

    The normal Zeeman effect gives rise to a three-fold splitting of atomic spectral lines in the presence of strong external magnetic fields. In n-doped semiconductor quantum wells, a similar three-fold splitting occurs in the intersubband spin plasmon resonance, as was recently demonstrated experimentally using inelastic light scattering. The plasmon splitting is caused by the interplay of intrinsic spin-orbit crystal magnetic fields and dynamical many-body effects. We show that it can be regarded as an intrinsic normal Zeeman effect in quantum wells. We present a formal framework for calculating the quantum well electronic states and their collective linear response in the presence of Rashba and Dresselhaus spin-orbit coupling, and we show how the intrinsic normal Zeeman effect of the spin plasmons can be controlled by external magnetic fields.

  18. Direct self-assembling and patterning of semiconductor quantum dots on transferable elastomer layer

    Energy Technology Data Exchange (ETDEWEB)

    Coppola, Sara [Institute of Applied Sciences and Intelligent System- CNR, Via Campi Flegrei 34, Pozzuoli, 80078 (Italy); Vespini, Veronica, E-mail: v.vespini@isasi.cnr.it [Institute of Applied Sciences and Intelligent System- CNR, Via Campi Flegrei 34, Pozzuoli, 80078 (Italy); Olivieri, Federico [Institute of Applied Sciences and Intelligent System- CNR, Via Campi Flegrei 34, Pozzuoli, 80078 (Italy); University of Naples Federico II, Department of Chemical Materials and Production Engineering, Piazzale Tecchio 80, Naples 80125 (Italy); Nasti, Giuseppe; Todino, Michele; Mandracchia, Biagio; Pagliarulo, Vito; Ferraro, Pietro [Institute of Applied Sciences and Intelligent System- CNR, Via Campi Flegrei 34, Pozzuoli, 80078 (Italy)

    2017-03-31

    Highlights: • A quantum dots self-patterning on micrometrical polymeric array is proposed. • The effect of a quantum dots mix on the array is evaluated. • A PDMS membrane is exploited to transfer the pattern on it. - Abstract: Functionalization of thin and stretchable polymer layers by nano- and micro-patterning of nanoparticles is a very promising field of research that can lead to many different applications in biology and nanotechnology. In this work, we present a new procedure to self-assemble semiconductor quantum dots (QDs) nanoparticles by a simple fabrication process on a freestanding flexible PolyDiMethylSiloxane (PDMS) membrane. We used a Periodically Poled Lithium Niobate (PPLN) crystal to imprint a micrometrical pattern on the PDMS membrane that drives the QDs self-structuring on its surface. This process allows patterning QDs with different wavelength emissions in a single step in order to tune the overall emission spectrum of the composite, tuning the QDs mixing ratio.

  19. Two stream instability in n-type gallium arsenide semiconductor quantum plasma

    Science.gov (United States)

    Ghosh, S.; Muley, Apurva

    2018-01-01

    By using quantum hydrodynamic model, we derive a generalized dielectric response function for two stream instability (convective only) in n-type gallium arsenide semiconductor plasma. We investigate the phase and amplification profiles of two stream instability with externally applied electric field ranging from 2600 to 4000 kV m-1 in presence of non-dimensional quantum parameter- H. In this range, a significant number of electrons in satellite valley become comparable to the number of electrons in central valley. The presence of quantum corrections in plasma medium induces two novel modes; one of it has amplifying nature and propagates in forward direction. It also modifies the spectral profile of four pre-existing modes in classical plasma. The existence of two stream instability is also established analytically by deriving the real part of longitudinal electrokinetic power flow density.

  20. Novel compound semiconductor devices based on III-V nitrides

    Energy Technology Data Exchange (ETDEWEB)

    Pearton, S.J.; Abernathy, C.R. [Florida Univ., Gainesville, FL (United States); Ren, F. [AT & T Bell Laboratories, Murray Hill, NJ (United States)] [and others

    1995-10-01

    New developments in dry and wet etching, ohmic contacts and epitaxial growth of Ill-V nitrides are reported. These make possible devices such as microdisk laser structures and GaAs/AlGaAs heterojunction bipolar transistors with improved InN ohmic contacts.

  1. A Process for the Manufacture of a Semiconductor Device

    NARCIS (Netherlands)

    Ishihara, R.; Van der Zwan, M.

    2013-01-01

    A method for the manufacture of at least part of a thin-film device is described wherein, said method comprise: forming one or more indentations in a substrate, preferably a plastic substrate, an indentation comprising sidewalls and a base; filling at least one of said one or more indentations with

  2. Surface Preparation and Deposited Gate Oxides for Gallium Nitride Based Metal Oxide Semiconductor Devices

    Science.gov (United States)

    Long, Rathnait D.; McIntyre, Paul C.

    2012-01-01

    The literature on polar Gallium Nitride (GaN) surfaces, surface treatments and gate dielectrics relevant to metal oxide semiconductor devices is reviewed. The significance of the GaN growth technique and growth parameters on the properties of GaN epilayers, the ability to modify GaN surface properties using in situ and ex situ processes and progress on the understanding and performance of GaN metal oxide semiconductor (MOS) devices are presented and discussed. Although a reasonably consistent picture is emerging from focused studies on issues covered in each of these topics, future research can achieve a better understanding of the critical oxide-semiconductor interface by probing the connections between these topics. The challenges in analyzing defect concentrations and energies in GaN MOS gate stacks are discussed. Promising gate dielectric deposition techniques such as atomic layer deposition, which is already accepted by the semiconductor industry for silicon CMOS device fabrication, coupled with more advanced physical and electrical characterization methods will likely accelerate the pace of learning required to develop future GaN-based MOS technology.

  3. The role of surface ligands in quantum-dot devices: Villain or unsung hero?

    Energy Technology Data Exchange (ETDEWEB)

    Pietryga, Jeffrey Michael [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2018-02-20

    For over three decades, the study of nanocrystal quantum dots (QDs), which are solution-synthesized nanometer-scale bits of semiconductor materials, has produced singular advances in both our understanding of quantum confinement effects, and in our ability to make use of them in tech-relevant materials. Accordingly, QDs have found their way into the marketplace, specifically as high-performance fluorophores for, e.g., displays and biolabeling. In such applications, optimization of the QD surface, including the passivating ligands, is key to keeping photo-excited carriers from leaving the QD interior before recombining, resulting in a high fluorescence efficiency. Increasingly, attention has turned to realize the promise of QDs for optoelectronic applications (e.g., solar cells, LEDs, sensors) which require charge carriers to controllably enter, exit and/or travel through QDs, a much more challenging problem. In this scenario, the role of the QD surface must be completely reimagined, from being an impenetrable wall to being a gateway, or even a ramp. In this talk, I’ll explore the inherent contrast between QD fluorophore and device applications, and describe how ligands, originally thought only to be impediments to QD electronic devices, may actually give the savvy QD device designer control over function and performance in a manner unknown in bulk semiconductor devices. Finally, I’ll survey recent efforts at Los Alamos to develop a universal tool box for deposition of conductive QD films that may finally allow the manufacturing of economical, high-performance devices for a wide range of applications.

  4. Electron–hole two-stream instability in a quantum semiconductor plasma with exchange-correlation effects

    International Nuclear Information System (INIS)

    Zeba, I.; Yahia, M.E.; Shukla, P.K.; Moslem, W.M.

    2012-01-01

    The electron–hole two-stream instability in a quantum semiconductor plasma has been studied including electrons and holes quantum recoil effects, exchange-correlation potentials, and degenerate pressures of the plasma species. Typical values of GaAs and GaSb semiconductors are used to estimate the growth rate of the two-stream instability. The effects of electron– and hole–phonon collision, quantum recoil effects, the streaming velocities, and the corresponding threshold on the growth rate are investigated numerically. Considering the phonon susceptibility allows the acoustic mode to exist and the collisional instability arises in combination with drift of the holes. -- Highlights: ► Electron–hole two stream instability in quantum plasmas is presented. ► Typical values of GaAs and GaSb semiconductors are used to estimate the growth rate. ► The streaming velocities and the corresponding threshold on the growth rate are investigated numerically.

  5. Improving the Performance of Semiconductor Sensor Devices Using Surface Functionalization

    Science.gov (United States)

    Rohrbaugh, Nathaniel W.

    As production and understanding of III-nitride growth has progressed, this class of material has been used for its semiconducting properties in the fields of computer processing, microelectronics, and LEDs. As understanding of materials properties has advanced, devices were fabricated to be sensitive to environmental surroundings such as pH, gas, or ionic concentration. Simultaneously the world of pharmaceuticals and environmental science has come to the age where the use of wearable devices and active environmental sensing can not only help us learn more about our surroundings, but help save lives. At the crossroads of these two fields work has been done in marrying the high stability and electrical properties of the III-nitrides with the needs of a growing sensor field for various environments and stimuli. Device architecture can only get one so far, and thus the need for well understood surface functionalization techniques has arisen in the field of III-nitride environmental sensing. Many existing schemes for functionalization involve chemistries that may be unfriendly to a biological environment, unstable in solution, or expensive to produce. One possible solution to these issues is the work presented here, which highlights a surface modification scheme utilizing phosphonic acid based chemistry and biomolecular attachment. This dissertation presents a set of studies and experiments quantifying and analyzing the response behaviors of AlGaN/GaN field effect transistor (FET) devices via their interfacial electronic properties. Additional investigation was done on the modification of these surfaces, effects of stressful environmental conditions, and the utility of the phosphonic acid surface treatments. Signals of AlGaN/GaN FETs were measured as IDrain values and in the earliest study an average signal increase of 96.43% was observed when surfaces were incubated in a solution of a known recognition peptide sequence (SVSVGMKPSPRP). This work showed that even without

  6. Peptide mediated intracellular delivery of semiconductor quantum dots

    Science.gov (United States)

    Kapur, Anshika; Safi, Malak; Domitrovic, Tatiana; Medina, Scott; Palui, Goutam; Johnson, John E.; Schneider, Joel; Mattoussi, Hedi

    2017-02-01

    As control over the growth, stabilization and functionalization of inorganic nanoparticles continue to advance, interest in integrating these materials with biological systems has steadily grown in the past decade. Much attention has been directed towards identifying effective approaches to promote cytosolic internalization of the nanoparticles while avoiding endocytosis. We describe the use of NωV virus derived gamma peptide and a chemically synthesized anticancer peptide, SVS-1 peptide, as vehicles to promote the non-endocytic uptake of luminescent quantum dots (QDs) inside live cells. The gamma peptide is expressed in E. coli as a fusion protein with poly-his tagged MBP (His-MBP-γ) to allow self-assembly onto QDs via metal-histidine conjugation. Conversely, the N-terminal cysteine residue of the SVS-1 peptide is attached to the functionalized QDs via covalent coupling chemistry. Epi-fluorescence microscopy images show that the QD-conjugate staining is distributed throughout the cytoplasm of cell cultures. Additionally, the QD staining does not show co-localization with transferrin-dye-labelled endosomes or DAPI stained nuclei. The QD uptake observed in the presence of physical and pharmacological endocytosis inhibitors further suggest that a physical translocation of QDs through the cell membrane is the driving mechanism for the uptake.

  7. Accelerated Aging System for Prognostics of Power Semiconductor Devices

    Science.gov (United States)

    Celaya, Jose R.; Vashchenko, Vladislav; Wysocki, Philip; Saha, Sankalita

    2010-01-01

    Prognostics is an engineering discipline that focuses on estimation of the health state of a component and the prediction of its remaining useful life (RUL) before failure. Health state estimation is based on actual conditions and it is fundamental for the prediction of RUL under anticipated future usage. Failure of electronic devices is of great concern as future aircraft will see an increase of electronics to drive and control safety-critical equipment throughout the aircraft. Therefore, development of prognostics solutions for electronics is of key importance. This paper presents an accelerated aging system for gate-controlled power transistors. This system allows for the understanding of the effects of failure mechanisms, and the identification of leading indicators of failure which are essential in the development of physics-based degradation models and RUL prediction. In particular, this system isolates electrical overstress from thermal overstress. Also, this system allows for a precise control of internal temperatures, enabling the exploration of intrinsic failure mechanisms not related to the device packaging. By controlling the temperature within safe operation levels of the device, accelerated aging is induced by electrical overstress only, avoiding the generation of thermal cycles. The temperature is controlled by active thermal-electric units. Several electrical and thermal signals are measured in-situ and recorded for further analysis in the identification of leading indicators of failures. This system, therefore, provides a unique capability in the exploration of different failure mechanisms and the identification of precursors of failure that can be used to provide a health management solution for electronic devices.

  8. Quantum computation: algorithms and implementation in quantum dot devices

    Science.gov (United States)

    Gamble, John King

    In this thesis, we explore several aspects of both the software and hardware of quantum computation. First, we examine the computational power of multi-particle quantum random walks in terms of distinguishing mathematical graphs. We study both interacting and non-interacting multi-particle walks on strongly regular graphs, proving some limitations on distinguishing powers and presenting extensive numerical evidence indicative of interactions providing more distinguishing power. We then study the recently proposed adiabatic quantum algorithm for Google PageRank, and show that it exhibits power-law scaling for realistic WWW-like graphs. Turning to hardware, we next analyze the thermal physics of two nearby 2D electron gas (2DEG), and show that an analogue of the Coulomb drag effect exists for heat transfer. In some distance and temperature, this heat transfer is more significant than phonon dissipation channels. After that, we study the dephasing of two-electron states in a single silicon quantum dot. Specifically, we consider dephasing due to the electron-phonon coupling and charge noise, separately treating orbital and valley excitations. In an ideal system, dephasing due to charge noise is strongly suppressed due to a vanishing dipole moment. However, introduction of disorder or anharmonicity leads to large effective dipole moments, and hence possibly strong dephasing. Building on this work, we next consider more realistic systems, including structural disorder systems. We present experiment and theory, which demonstrate energy levels that vary with quantum dot translation, implying a structurally disordered system. Finally, we turn to the issues of valley mixing and valley-orbit hybridization, which occurs due to atomic-scale disorder at quantum well interfaces. We develop a new theoretical approach to study these effects, which we name the disorder-expansion technique. We demonstrate that this method successfully reproduces atomistic tight-binding techniques

  9. Emergence of the persistent spin helix in semiconductor quantum wells

    International Nuclear Information System (INIS)

    Koralek, Jake; Weber, Chris; Orenstein, Joe; Bernevig, Andrei; Zhang, Shoucheng; Mack, Shawn; Awschalom, David

    2008-01-01

    According to Noether's theorem, for every symmetry in nature there is a corresponding conservation law. For example, invariance with respect to spatial translation corresponds to conservation of momentum. In another well-known example, invariance with respect to rotation of the electron's spin, or SU(2) symmetry, leads to conservation of spin polarization. For electrons in a solid, this symmetry is ordinarily broken by spin-orbit (SO) coupling, allowing spin angular momentum to flow to orbital angular momentum. However, it has recently been predicted that SU(2) can be recovered in a two-dimensional electron gas (2DEG), despite the presence of SO coupling. The corresponding conserved quantities include the amplitude and phase of a helical spin density wave termed the 'persistent spin helix' (PSH) .2 SU(2) is restored, in principle, when the strength of two dominant SO interactions, the Rashba (alpha) and linear Dresselhaus (beta 1), are equal. This symmetry is predicted to be robust against all forms of spin-independent scattering, including electron-electron interactions, but is broken by the cubic Dresselhaus term (beta 3) and spin-dependent scattering. When these terms are negligible, the distance over which spin information can propagate is predicted to diverge as alpha approaches beta 1. Here we observe experimentally the emergence of the PSH in GaAs quantum wells (QW's) by independently tuning alpha and beta 1. Using transient spin-grating spectroscopy (TSG), we find a spin-lifetime enhancement of two orders of magnitude near the symmetry point. Excellent quantitative agreement with theory across a wide range of sample parameters allows us to obtain an absolute measure of all relevant SO terms, identifying beta 3 as the main SU(2) violating term in our samples. The tunable suppression of spin-relaxation demonstrated in this work is well-suited for application to spintronics

  10. Emergence of the Persistent Spin Helix in Semiconductor Quantum Wells

    International Nuclear Information System (INIS)

    Koralek, Jake

    2011-01-01

    According to Noether's theorem, for every symmetry in nature there is a corresponding conservation law. For example, invariance with respect to spatial translation corresponds to conservation of momentum. In another well-known example, invariance with respect to rotation of the electron's spin, or SU(2) symmetry, leads to conservation of spin polarization. For electrons in a solid, this symmetry is ordinarily broken by spin-orbit (SO) coupling, allowing spin angular momentum to flow to orbital angular momentum. However, it has recently been predicted that SU(2) can be recovered in a two-dimensional electron gas (2DEG), despite the presence of SO coupling. The corresponding conserved quantities include the amplitude and phase of a helical spin density wave termed the 'persistent spin helix' (PSH). SU(2) is restored, in principle, when the strength of two dominant SO interactions, the Rashba (α) and linear Dresselhaus (β 1 ), are equal. This symmetry is predicted to be robust against all forms of spin-independent scattering, including electron-electron interactions, but is broken by the cubic Dresselhaus term (β 3 ) and spin-dependent scattering. When these terms are negligible, the distance over which spin information can propagate is predicted to diverge as α → β 1 . Here we observe experimentally the emergence of the PSH in GaAs quantum wells (QW's) by independently tuning α and β 1 . Using transient spin-grating spectroscopy (TSG), we find a spin-lifetime enhancement of two orders of magnitude near the symmetry point. Excellent quantitative agreement with theory across a wide range of sample parameters allows us to obtain an absolute measure of all relevant SO terms, identifying β 3 as the main SU(2) violating term in our samples. The tunable suppression of spin-relaxation demonstrated in this work is well-suited for application to spintronics.

  11. Magneto-Gyrotropic Photogalvanic Effects in Semiconductor Quantum Wells

    Science.gov (United States)

    Ganichev, S. D.

    The spin-orbit coupling provides a versatile tool to generate and to manipulate the spin degree of freedom in low-dimensional semiconductor structures. The spin Hall effect, where an electric current drives a transverse spin current and causes a nonequilibrium spin accumulation near the sample boundary,1,2 the spin-galvanic effect, where a nonequilibrium spin polarization drives an electric current3,4 or the reverse process, in which an electrical current generates a non-equilibrium spin-polarization,5-9 are all consequences of spin-orbit coupling. In order to observe a spin Hall effect a bias driven current is an essential prerequisite. Then spin separation is caused via spin-orbit coupling either by Mott scattering (extrinsic spin Hall effect) or by spin splitting of the band structure (intrinsic spin Hall effect). Recently an elementary effect causing spin separation which is fundamentally different from that of the spin Hall effect has been observed.10 In contrast to the spin Hall effect it does not require an electric current to flow: it is spin separation achieved by spin-dependent scattering of electrons in media with suitable symmetry. It is show that by free carrier (Drude) absorption of terahertz radiation spin separation is achieved in a wide range of temperatures from liquid helium temperature up to room temperature. Moreover the experimental results demonstrate that simple electron gas heating by any means is already sufficient to yield spin separation due to spin-dependent energy relaxation processes of non-equilibrium carriers. In order to demonstrate the existence of the spin separation due to asymmetric scattering the pure spin current was converted into an electric current. It is achieved by application of a magnetic field which polarizes spins. This is analogues to spin-dependent scattering in transport experiments: spin-dependent scattering in an unpolarized electron gas causes the extrinsic spin Hall effect, whereas in a spin-polarized electron

  12. Development of Quantum Devices and Algorithms for Radiation Detection and Radiation Signal Processing

    International Nuclear Information System (INIS)

    El Tokhy, M.E.S.M.E.S.

    2012-01-01

    The main functions of spectroscopy system are signal detection, filtering and amplification, pileup detection and recovery, dead time correction, amplitude analysis and energy spectrum analysis. Safeguards isotopic measurements require the best spectrometer systems with excellent resolution, stability, efficiency and throughput. However, the resolution and throughput, which depend mainly on the detector, amplifier and the analog-to-digital converter (ADC), can still be improved. These modules have been in continuous development and improvement. For this reason we are interested with both the development of quantum detectors and efficient algorithms of the digital processing measurement. Therefore, the main objective of this thesis is concentrated on both 1. Study quantum dot (QD) devices behaviors under gamma radiation 2. Development of efficient algorithms for handling problems of gamma-ray spectroscopy For gamma radiation detection, a detailed study of nanotechnology QD sources and infrared photodetectors (QDIP) for gamma radiation detection is introduced. There are two different types of quantum scintillator detectors, which dominate the area of ionizing radiation measurements. These detectors are QD scintillator detectors and QDIP scintillator detectors. By comparison with traditional systems, quantum systems have less mass, require less volume, and consume less power. These factors are increasing the need for efficient detector for gamma-ray applications such as gamma-ray spectroscopy. Consequently, the nanocomposite materials based on semiconductor quantum dots has potential for radiation detection via scintillation was demonstrated in the literature. Therefore, this thesis presents a theoretical analysis for the characteristics of QD sources and infrared photodetectors (QDIPs). A model of QD sources under incident gamma radiation detection is developed. A novel methodology is introduced to characterize the effect of gamma radiation on QD devices. The rate

  13. Characterization of Semiconductor Nanocrystal Assemblies as Components of Optoelectronic Devices

    Science.gov (United States)

    Malfavon-Ochoa, Mario

    This dissertation presents new insight into the ability of small molecule passivated NCs to achieve intimate approach distances, despite being well passivated, while developing guiding principles in the area of ligand mediated microstructure control and the resulting macroscopic optical and electronic properties that close packing of high quality NCs enables. NC ligand coverage will be characterized quantitatively through thermogravimetric analysis (TGA), and qualitatively by photoluminescence and electroluminescence, in the case of functional devices; illustrating the importance of practitioner dependent control of ligand coverage through variations in the dispersion precipitation purification procedure. A unique examination of the relative contribution of energy and charge transfer in NC LEDs will demonstrate the ability to achieve charge transfer, at a level competitive with energy transfer, to well passivated NCs at various wt% loading in a polymer matrix. The observation of potential dependent recombination zones within an active layer further suggest novel, NC surface passivation mediated control of blend microstructure during solution processing towards the development of a bi-continuous network. Next, NC self-assembly and resulting microstructure dependent optical and electronic properties will be examined through electroluminescence and high-resolution transmission electron microscopy (TEM) micrographs of functional NC/polymer bulk heterojunction LEDs. The joint characterization of NC optical properties, and self-assembly microstructure provide a deeper understanding of the significant and inseparable effects of minimal changes in NC surface passivation on structure and function, and emphasize the potential to rely on strongly passivating ligands to control physical properties and processing parameters concurrently towards higher efficiency devices via low cost processing. Finally, micro-contact printing of blazed transmission gratings, using stable

  14. Use of a scanning electron microscope for characterizing semiconductor devices

    International Nuclear Information System (INIS)

    Borel, J.; Bresse, J.F.; Carme, H.; Monnier, J.

    1974-01-01

    The electron beam from the scanning microscope had three different uses: 1) in induced mode for characterizing the substrate of a P + N junction by measuring the diffusion length and in controlling surface recombination velocities; 2) for controlling Si/SiO 2 interface degradation by measuring very low frequency capacitance and for evaluating the oxide quality by measuring μ/tau: application to the fast control of any device, in this case the evolution of the current of an avalanche photodiode; 3) in using the beam as a Castaing probe for determining features of the generation volume, Si thickness on Al 2 O 3 , or Si thickness [fr

  15. Robustness and device independence of verifiable blind quantum computing

    International Nuclear Information System (INIS)

    Gheorghiu, Alexandru; Kashefi, Elham; Wallden, Petros

    2015-01-01

    Recent advances in theoretical and experimental quantum computing bring us closer to scalable quantum computing devices. This makes the need for protocols that verify the correct functionality of quantum operations timely and has led to the field of quantum verification. In this paper we address key challenges to make quantum verification protocols applicable to experimental implementations. We prove the robustness of the single server verifiable universal blind quantum computing protocol of Fitzsimons and Kashefi (2012 arXiv:1203.5217) in the most general scenario. This includes the case where the purification of the deviated input state is in the hands of an adversarial server. The proved robustness property allows the composition of this protocol with a device-independent state tomography protocol that we give, which is based on the rigidity of CHSH games as proposed by Reichardt et al (2013 Nature 496 456–60). The resulting composite protocol has lower round complexity for the verification of entangled quantum servers with a classical verifier and, as we show, can be made fault tolerant. (paper)

  16. Multiplexed charge-locking device for large arrays of quantum devices

    Energy Technology Data Exchange (ETDEWEB)

    Puddy, R. K., E-mail: rkp27@cam.ac.uk; Smith, L. W; Chong, C. H.; Farrer, I.; Griffiths, J. P.; Ritchie, D. A.; Smith, C. G. [Cavendish Laboratory, University of Cambridge, Cambridge CB3 0HE (United Kingdom); Al-Taie, H.; Kelly, M. J. [Cavendish Laboratory, University of Cambridge, Cambridge CB3 0HE (United Kingdom); Centre for Advanced Photonics and Electronics, Electrical Engineering Division, Department of Engineering, 9 J. J. Thomson Avenue, University of Cambridge, Cambridge CB3 0FA (United Kingdom); Pepper, M. [Department of Electronic and Electrical Engineering, University College London, WC1E 7JE (United Kingdom)

    2015-10-05

    We present a method of forming and controlling large arrays of gate-defined quantum devices. The method uses an on-chip, multiplexed charge-locking system and helps to overcome the restraints imposed by the number of wires available in cryostat measurement systems. The device architecture that we describe here utilises a multiplexer-type scheme to lock charge onto gate electrodes. The design allows access to and control of gates whose total number exceeds that of the available electrical contacts and enables the formation, modulation and measurement of large arrays of quantum devices. We fabricate such devices on n-type GaAs/AlGaAs substrates and investigate the stability of the charge locked on to the gates. Proof-of-concept is shown by measurement of the Coulomb blockade peaks of a single quantum dot formed by a floating gate in the device. The floating gate is seen to drift by approximately one Coulomb oscillation per hour.

  17. RADIATION PERFORMANCE OF GAN AND INAS/GAAS QUANTUM DOT BASED DEVICES SUBJECTED TO NEUTRON RADIATION

    Directory of Open Access Journals (Sweden)

    Dhiyauddin Ahmad Fauzi

    2017-05-01

    Full Text Available In addition to their useful optoelectronics functions, gallium nitride (GaN and quantum dots (QDs based structures are also known for their radiation hardness properties. With demands on such semiconductor material structures, it is important to investigate the differences in reliability and radiation hardness properties of these two devices. For this purpose, three sets of GaN light-emitting diode (LED and InAs/GaAs dot-in-a well (DWELL samples were irradiated with thermal neutron of fluence ranging from 3×1013 to 6×1014 neutron/cm2 in PUSPATI TRIGA research reactor. The radiation performances for each device were evaluated based on the current-voltage (I-V and capacitance-voltage (C-V electrical characterisation method. Results suggested that the GaN based sample is less susceptible to electrical changes due to the thermal neutron radiation effects compared to the QD based sample.

  18. Threshold for photoelectric emission from a quantum ring of narrow-gap semiconductor

    International Nuclear Information System (INIS)

    Das, N.R.; Sen, Susmita

    2008-01-01

    In this paper, we have investigated the threshold energy required for photoelectric emission of electrons from a torroidal quantum ring of degenerate narrow-gap semiconductor. Current density due to electrons emitted from the ring illuminated by normal radiation has been calculated considering the effect of band non-parabolicity of the narrow-gap semiconductor. The computed results show that the current density increases in a staircase manner with the increase of incident photon energy. The band non-parabolicity causes the increase in threshold energy for photoelectric emission of electrons. The photoemission becomes an oscillatory function of the cross-sectional radius of the ring, and may serve as an important tool for estimating parameters like cross-sectional radius, doping density and band non-parabolicity

  19. Comparative examination of the stability of semiconductor quantum dots in various biochemical buffers.

    Science.gov (United States)

    Boldt, Klaus; Bruns, Oliver T; Gaponik, Nikolai; Eychmüller, Alexander

    2006-02-09

    Due to their greater photostability compared to established organic fluorescence markers, semiconductor quantum dots provide an attractive alternative for the biolabeling of living cells. On the basis of a comparative investigation using differently sized thiol-stabilized CdTe nanocrystals in a variety of commonly used biological buffers, a method is developed to quantify the stability of such a multicomponent system. Above a certain critical size, the intensity of the photoluminescence of the nanocrystals is found to diminish with pseudo-zero-order kinetics, whereas for specific combinations of particle size, ligand, and buffer there appears to be no decay below this critical particle size, pointing out the necessity for thorough investigations of this kind in the view of prospect applications of semiconductor nanocrystals in the area of biolabeling.

  20. Thermal modeling of wide bandgap semiconductor devices for high frequency power converters

    Science.gov (United States)

    Sharath Sundar Ram, S.; Vijayakumari, A.

    2018-02-01

    The emergence of wide bandgap semiconductors has led to development of new generation semiconductor switches that are highly efficient and scalable. To exploit the advantages of GaNFETs in power converters, in terms of reduction in the size of heat sinks and filters, a thorough understanding of the thermal behavior of the device is essential. This paper aims to establish a thermal model for wideband gap semiconductor GaNFETs commercially available, which will enable power electronic designers to obtain the thermal characteristics of the device more effectively. The model parameters is obtained from the manufacturer’s data sheet by adopting an exponential curve fitting technique and the thermal model is validated using PSPICE simulations. The model was developed based on the parametric equivalence that exists between the thermal and electrical components, such that it responds for transient thermal stresses. A suitable power profile has been generated to evaluate the GaNFET model under different power dissipation scenarios. The results were compared with a Silicon MOSFETs to further highlight the advantages of the GaN devices. The proposed modeling approach can be extended for other GaN devices and can provide a platform for the thermal study and heat sink optimization.

  1. Quantum communications system with integrated photonic devices

    Energy Technology Data Exchange (ETDEWEB)

    Nordholt, Jane E.; Peterson, Charles Glen; Newell, Raymond Thorson; Hughes, Richard John

    2017-11-14

    Security is increased in quantum communication (QC) systems lacking a true single-photon laser source by encoding a transmitted optical signal with two or more decoy-states. A variable attenuator or amplitude modulator randomly imposes average photon values onto the optical signal based on data input and the predetermined decoy-states. By measuring and comparing photon distributions for a received QC signal, a single-photon transmittance is estimated. Fiber birefringence is compensated by applying polarization modulation. A transmitter can be configured to transmit in conjugate polarization bases whose states of polarization (SOPs) can be represented as equidistant points on a great circle on the Poincare sphere so that the received SOPs are mapped to equidistant points on a great circle and routed to corresponding detectors. Transmitters are implemented in quantum communication cards and can be assembled from micro-optical components, or transmitter components can be fabricated as part of a monolithic or hybrid chip-scale circuit.

  2. Investigation of plasma etch induced damage in compound semiconductor devices

    Energy Technology Data Exchange (ETDEWEB)

    Shul, R.J.; Lovejoy, M.L.; Hetherington, D.L.; Rieger, D.J.; Vawter, G.A.; Klem, J.F. [Sandia National Labs., Albuquerque, NM (United States); Melloch, M.R. [Purdue Univ., Lafayette, IN (United States). School of Electrical Engineering

    1993-11-01

    We have investigated the electrical performance of mesa-isolated GaAs pn-junction diodes to determine the plasma-induced damage effects from reactive ion and reactive ion beam etching. A variety of plasma chemistries (SiCl{sub 4}, BCl{sub 3}, BCl{sub 3}/Cl{sub 2}, and Cl{sub 2}) and ion energies ranging from 100 to 400 eV were studied. We have observed that many of the RIE BCl{sub 3}/Cl{sub 2} plasmas and RIBE Cl{sub 2} plasmas yield diodes with low reverse-bias currents that are comparable to the electrical characteristics of wet-chemical-etched devices. The reverse-bias leakage currents are independent of surface morphology and sidewall profiles.

  3. Toxicological studies of semiconductor quantum dots on immune cells.

    Energy Technology Data Exchange (ETDEWEB)

    Ricken, James Bryce; Rios, Lynette; Poschet, Jens Fredrich; Bachand, Marlene; Bachand, George David; Greene, Adrienne Celeste; Carroll-Portillo, Amanda

    2008-11-01

    Nanoengineered materials hold a vast promise of enabling revolutionary technologies, but also pose an emerging and potentially serious threat to human and environmental health. While there is increasing knowledge concerning the risks posed by engineered nanomaterials, significant inconsistencies exist within the current data based on the high degree of variability in the materials (e.g., synthesis method, coatings, etc) and biological test systems (e.g., cell lines, whole organism, etc). In this project, we evaluated the uptake and response of two immune cell lines (RAW macrophage and RBL mast cells) to nanocrystal quantum dots (Qdots) with different sizes and surface chemistries, and at different concentrations. The basic experimental design followed a 2 x 2 x 3 factorial model: two Qdot sizes (Qdot 520 and 620), two surface chemistries (amine 'NH{sub 2}' and carboxylic acid 'COOH'), and three concentrations (0, 1 nM, and 1 {micro}M). Based on this design, the following Qdots from Evident Technologies were used for all experiments: Qdot 520-COOH, Qdot 520-NH{sub 2}, Qdot 620-COOH, and Qdot 620-NH{sub 2}. Fluorescence and confocal imaging demonstrated that Qdot 620-COOH and Qdot 620-NH{sub 2} nanoparticles had a greater level of internalization and cell membrane association in RAW and RBL cells, respectively. From these data, a two-way interaction between Qdot size and concentration was observed in relation to the level of cellular uptake in RAW cells, and association with RBL cell membranes. Toxicity of both RBL and RAW cells was also significantly dependent on the interaction of Qdot size and concentration; the 1 {micro}M concentrations of the larger, Qdot 620 nanoparticles induced a greater toxic effect on both cell lines. The RBL data also demonstrate that Qdot exposure can induce significant toxicity independent of cellular uptake. A significant increase in TNF-{alpha} and decrease in IL-10 release was observed in RAW cells, and suggested

  4. Dynamic detection of spin accumulation in ferromagnet-semiconductor devices by ferromagnetic resonance (Conference Presentation)

    Science.gov (United States)

    Crowell, Paul A.; Liu, Changjiang; Patel, Sahil; Peterson, Tim; Geppert, Chad C.; Christie, Kevin; Stecklein, Gordon; Palmstrøm, Chris J.

    2016-10-01

    A distinguishing feature of spin accumulation in ferromagnet-semiconductor devices is its precession in a magnetic field. This is the basis for detection techniques such as the Hanle effect, but these approaches become ineffective as the spin lifetime in the semiconductor decreases. For this reason, no electrical Hanle measurement has been demonstrated in GaAs at room temperature. We show here that by forcing the magnetization in the ferromagnet to precess at resonance instead of relying only on the Larmor precession of the spin accumulation in the semiconductor, an electrically generated spin accumulation can be detected up to 300 K. The injection bias and temperature dependence of the measured spin signal agree with those obtained using traditional methods. We further show that this new approach enables a measurement of short spin lifetimes (C. Liu, S. J. Patel, T. A. Peterson, C. C. Geppert, K. D. Christie, C. J. Palmstrøm, and P. A. Crowell, "Dynamic detection of electron spin accumulation in ferromagnet-semiconductor devices by ferromagnetic resonance," Nature Communications 7, 10296 (2016). http://dx.doi.org/10.1038/ncomms10296

  5. Large and tunable negative refractive index via electromagnetically induced chirality in a semiconductor quantum well nanostructure

    Science.gov (United States)

    Zhao, Sh.-C.; Zhang, Sh.-Y.; Xu, Y.-Y.

    2014-11-01

    Large and tunable negative refractive index (NRI) via electromagnetically induced chirality is demonstrated in a semiconductor quantum wells (SQWs) nanostructure by using the reported experimental parameters in J.F. Dynes et al., Phys. Rev. Lett. 94, 157403 (2005). It is found: the large and controllable NRI with alterable frequency regions is obtained when the coupling laser field and the relative phase are modulated, which will increase the flexibility and possibility of implementing NRI in the SQWs nanostructure. The scheme rooted in the experimental results may lead a new avenue to NRI material in solid-state nanostructure.

  6. Theory of Pulse Train Amplification Without Patterning Effects in Quantum Dot Semiconductor Optical Amplifiers

    DEFF Research Database (Denmark)

    Uskov, Alexander V.; Berg, Tommy Winther; Mørk, Jesper

    2004-01-01

    A theory for pulse amplification and saturation in quantum dot (QD) semiconductor optical amplifiers (SOAs) is developed. In particular, the maximum bit rate at which a data stream of pulses can be amplified without significant patterning effects is investigated. Simple expressions are derived th...... energies of 0.2–0.4 pJ. The superiority of QD SOAs is based on: 1) the faster achievement of the regime of maximum gain in QD SOAs compared to QW and bulk SOAs and 2) the lower effective cross section of photon-carrier interaction in QDs....

  7. Quantum Wells, Wires and Dots Theoretical and Computational Physics of Semiconductor Nanostructures

    CERN Document Server

    Harrison, Paul

    2011-01-01

    Quantum Wells, Wires and Dots, 3rd Edition is aimed at providing all the essential information, both theoretical and computational, in order that the reader can, starting from essentially nothing, understand how the electronic, optical and transport properties of semiconductor heterostructures are calculated. Completely revised and updated, this text is designed to lead the reader through a series of simple theoretical and computational implementations, and slowly build from solid foundations, to a level where the reader can begin to initiate theoretical investigations or explanations of their

  8. Memory attacks on device-independent quantum cryptography.

    Science.gov (United States)

    Barrett, Jonathan; Colbeck, Roger; Kent, Adrian

    2013-01-04

    Device-independent quantum cryptographic schemes aim to guarantee security to users based only on the output statistics of any components used, and without the need to verify their internal functionality. Since this would protect users against untrustworthy or incompetent manufacturers, sabotage, or device degradation, this idea has excited much interest, and many device-independent schemes have been proposed. Here we identify a critical weakness of device-independent protocols that rely on public communication between secure laboratories. Untrusted devices may record their inputs and outputs and reveal information about them via publicly discussed outputs during later runs. Reusing devices thus compromises the security of a protocol and risks leaking secret data. Possible defenses include securely destroying or isolating used devices. However, these are costly and often impractical. We propose other more practical partial defenses as well as a new protocol structure for device-independent quantum key distribution that aims to achieve composable security in the case of two parties using a small number of devices to repeatedly share keys with each other (and no other party).

  9. AlN film deposition as a semiconductor device

    Directory of Open Access Journals (Sweden)

    Julio Cesar Caicedo

    2013-05-01

    Full Text Available AlN films were deposited by pulsed laser deposition (PLD using an Nd: YAG laser (λ = 1064 nm. The films were deposited in a nitrogen atmosphere as working gas; the cathode was an aluminium high purity (99.99% target. The films were deposited using 7 J/cm2 laser fluence for 10 minutes on silicon (100 substrates. The working pressure was 9x10-3 mbar and the substrate temperature was varied from 200°C to 630°C. The thickness measured by profilometer was 150 nm for all films. Moreover, surface acoustic wave (SAW devices with a Mo/AlN/Si configuration have been fabricated using AlN-buffer and Mo Channel. The films’ morphology and composition were studied using scanning electron microscopy (SEM and energy dispersive X-ray analysis (EDX, respectively. The films’ optical reflectance spectra and colour coordinates were obtained by optical spectral reflectometry in the 400-900 cm-1 range using an Ocean Optics 2000 spectrophotometer. The present work found clear dependence on morphological properties, reflectance, dominant wavelength colour purity, frequency response and acoustic wave speed in terms of the temperature applied to the substrate. About 30% reduction in reflectance was observed and increased acoustic wave speed of about 1.3 % when the temperature was increased from 200°C to 630°C.

  10. Predicting the valley physics of silicon quantum dots directly from a device layout

    Science.gov (United States)

    Gamble, John King; Harvey-Collard, Patrick; Jacobson, N. Tobias; Bacewski, Andrew D.; Nielsen, Erik; Montaño, Inès; Rudolph, Martin; Carroll, Malcolm S.; Muller, Richard P.

    Qubits made from electrostatically-defined quantum dots in Si-based systems are excellent candidates for quantum information processing applications. However, the multi-valley structure of silicon's band structure provides additional challenges for the few-electron physics critical to qubit manipulation. Here, we present a theory for valley physics that is predictive, in that we take as input the real physical device geometry and experimental voltage operation schedule, and with minimal approximation compute the resulting valley physics. We present both effective mass theory and atomistic tight-binding calculations for two distinct metal-oxide-semiconductor (MOS) quantum dot systems, directly comparing them to experimental measurements of the valley splitting. We conclude by assessing these detailed simulations' utility for engineering desired valley physics in future devices. Sandia is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the US Department of Energy's National Nuclear Security Administration under Contract No. DE-AC04-94AL85000. The authors gratefully acknowledge support from the Sandia National Laboratories Truman Fellowship Program, which is funded by the Laboratory Directed Research and Development (LDRD) Program.

  11. Direct Nanoscale Sensing of the Internal Electric Field in Operating Semiconductor Devices Using Single Electron Spins.

    Science.gov (United States)

    Iwasaki, Takayuki; Naruki, Wataru; Tahara, Kosuke; Makino, Toshiharu; Kato, Hiromitsu; Ogura, Masahiko; Takeuchi, Daisuke; Yamasaki, Satoshi; Hatano, Mutsuko

    2017-02-28

    The electric field inside semiconductor devices is a key physical parameter that determines the properties of the devices. However, techniques based on scanning probe microscopy are limited to sensing at the surface only. Here, we demonstrate the direct sensing of the internal electric field in diamond power devices using single nitrogen-vacancy (NV) centers. The NV center embedded inside the device acts as a nanoscale electric field sensor. We fabricated vertical diamond p-i-n diodes containing the single NV centers. By performing optically detected magnetic resonance measurements under reverse-biased conditions with an applied voltage of up to 150 V, we found a large splitting in the magnetic resonance frequencies. This indicated that the NV center senses the transverse electric field in the space-charge region formed in the i-layer. The experimentally obtained electric field values are in good agreement with those calculated by a device simulator. Furthermore, we demonstrate the sensing of the electric field in different directions by utilizing NV centers with different N-V axes. This direct and quantitative sensing method using an electron spin in a wide-band-gap material provides a way to monitor the electric field in operating semiconductor devices.

  12. Device-independent quantum key distribution secure against collective attacks

    International Nuclear Information System (INIS)

    Pironio, Stefano; Gisin, Nicolas; AcIn, Antonio; Brunner, Nicolas; Massar, Serge; Scarani, Valerio

    2009-01-01

    Device-independent quantum key distribution (DIQKD) represents a relaxation of the security assumptions made in usual quantum key distribution (QKD). As in usual QKD, the security of DIQKD follows from the laws of quantum physics, but contrary to usual QKD, it does not rely on any assumptions about the internal working of the quantum devices used in the protocol. In this paper, we present in detail the security proof for a DIQKD protocol introduced in AcIn et al (2008 Phys. Rev. Lett. 98 230501). This proof exploits the full structure of quantum theory (as opposed to other proofs that exploit only the no-signaling principle), but only holds against collective attacks, where the eavesdropper is assumed to act on the quantum systems of the honest parties independently and identically in each round of the protocol (although she can act coherently on her systems at any time). The security of any DIQKD protocol necessarily relies on the violation of a Bell inequality. We discuss the issue of loopholes in Bell experiments in this context.

  13. Rapid parallelization of the drift-diffusion model for semiconductor devices

    OpenAIRE

    Gazzaniga, Giovanna; Lanucara, Piero; Pietra, Paola; Rovida, Sergio; Sacchi, Gianni

    2002-01-01

    The expensive reengineering of the sequential software and the difficult parallel programming are two of the many technical and economic obstacles to the wide use of HPC. We investigate the chance to improve, in a rapid way, the performance of a numerical serial code modelling semiconductor devices, exploiting the parallel features of shared memory architectures. OpenMP seems to be the good choice in order to guarantee the portability, that is one of the big issues in parall...

  14. An efficient method-of-lines simulation procedure for organic semiconductor devices.

    Science.gov (United States)

    Rogel-Salazar, J; Bradley, D D C; Cash, J R; Demello, J C

    2009-03-14

    We describe an adaptive grid method-of-lines (MOL) solution procedure for modelling charge transport and recombination in organic semiconductor devices. The procedure we describe offers an efficient, robust and versatile means of simulating semiconductor devices that allows for much simpler coding of the underlying equations than alternative simulation procedures. The MOL technique is especially well-suited to modelling the extremely stiff (and hence difficult to solve) equations that arise during the simulation of organic-and some inorganic-semiconductor devices. It also has wider applications in other areas, including reaction kinetics, combustion and aero- and fluid dynamics, where its ease of implementation also makes it an attractive choice. The MOL procedure we use converts the underlying semiconductor equations into a series of coupled ordinary differential equations (ODEs) that can be integrated forward in time using an appropriate ODE solver. The time integration is periodically interrupted, the numerical solution is interpolated onto a new grid that is better matched to the solution profile, and the time integration is then resumed on the new grid. The efficacy of the simulation procedure is assessed by considering a single layer device structure, for which exact analytical solutions are available for the electric potential, the charge distributions and the current-voltage characteristics. Two separate state-of-the-art ODE solvers are tested: the single-step Runge-Kutta solver Radau5 and the multi-step solver ODE15s, which is included as part of the Matlab ODE suite. In both cases, the numerical solutions show excellent agreement with the exact analytical solutions, yielding results that are accurate to one part in 1 x 10(4). The single-step Radau5 solver, however, is found to provide faster convergence since its efficiency is not compromised by the periodic interruption of the time integration when the grid is updated.

  15. Open quantum spin systems in semiconductor quantum dots and atoms in optical lattices

    International Nuclear Information System (INIS)

    Schwager, Heike

    2012-01-01

    In this Thesis, we study open quantum spin systems from different perspectives. The first part is motivated by technological challenges of quantum computation. An important building block for quantum computation and quantum communication networks is an interface between material qubits for storage and data processing and travelling photonic qubits for communication. We propose the realisation of a quantum interface between a travelling-wave light field and the nuclear spins in a quantum dot strongly coupled to a cavity. Our scheme is robust against cavity decay as it uses the decay of the cavity to achieve the coupling between nuclear spins and the travelling-wave light fields. A prerequiste for such a quantum interface is a highly polarized ensemble of nuclear spins. High polarization of the nuclear spin ensemble is moreover highly desirable as it protects the potential electron spin qubit from decoherence. Here we present the theoretical description of an experiment in which highly asymmetric dynamic nuclear spin pumping is observed in a single self-assembled InGaAs quantum dot. The second part of this Thesis is devoted to fundamental studies of dissipative spin systems. We study general one-dimensional spin chains under dissipation and propose a scheme to realize a quantum spin system using ultracold atoms in an optical lattice in which both coherent interaction and dissipation can be engineered and controlled. This system enables the study of non-equilibrium and steady state physics of open and driven spin systems. We find, that the steady state expectation values of different spin models exhibit discontinuous behaviour at degeneracy points of the Hamiltonian in the limit of weak dissipation. This effect can be used to dissipatively probe the spectrum of the Hamiltonian. We moreover study spin models under the aspect of state preparation and show that dissipation drives certain spin models into highly entangled state. Finally, we study a spin chain with

  16. Open quantum spin systems in semiconductor quantum dots and atoms in optical lattices

    Energy Technology Data Exchange (ETDEWEB)

    Schwager, Heike

    2012-07-04

    In this Thesis, we study open quantum spin systems from different perspectives. The first part is motivated by technological challenges of quantum computation. An important building block for quantum computation and quantum communication networks is an interface between material qubits for storage and data processing and travelling photonic qubits for communication. We propose the realisation of a quantum interface between a travelling-wave light field and the nuclear spins in a quantum dot strongly coupled to a cavity. Our scheme is robust against cavity decay as it uses the decay of the cavity to achieve the coupling between nuclear spins and the travelling-wave light fields. A prerequiste for such a quantum interface is a highly polarized ensemble of nuclear spins. High polarization of the nuclear spin ensemble is moreover highly desirable as it protects the potential electron spin qubit from decoherence. Here we present the theoretical description of an experiment in which highly asymmetric dynamic nuclear spin pumping is observed in a single self-assembled InGaAs quantum dot. The second part of this Thesis is devoted to fundamental studies of dissipative spin systems. We study general one-dimensional spin chains under dissipation and propose a scheme to realize a quantum spin system using ultracold atoms in an optical lattice in which both coherent interaction and dissipation can be engineered and controlled. This system enables the study of non-equilibrium and steady state physics of open and driven spin systems. We find, that the steady state expectation values of different spin models exhibit discontinuous behaviour at degeneracy points of the Hamiltonian in the limit of weak dissipation. This effect can be used to dissipatively probe the spectrum of the Hamiltonian. We moreover study spin models under the aspect of state preparation and show that dissipation drives certain spin models into highly entangled state. Finally, we study a spin chain with

  17. Monolithically integrated quantum dot optical gain modulator with semiconductor optical amplifier for 10-Gb/s photonic transmission

    Science.gov (United States)

    Yamamoto, Naokatsu; Akahane, Kouichi; Umezawa, Toshimasa; Kawanishi, Tetsuya

    2015-03-01

    Short-range interconnection and/or data center networks require high capacity and a large number of channels in order to support numerous connections. Solutions employed to meet these requirements involve the use of alternative wavebands to increase the usable optical frequency range. We recently proposed the use of the T- and O-bands (Thousand band: 1000-1260 nm, Original band: 1260-1360 nm) as alternative wavebands because large optical frequency resources (>60 THz) can be easily employed. In addition, a simple and compact Gb/s-order high-speed optical modulator is a critical photonic device for short-range communications. Therefore, to develop an optical modulator that acts as a highfunctional photonic device, we focused on the use of self-assembled quantum dots (QDs) as a three-dimensional (3D) confined structure because QD structures are highly suitable for realizing broadband optical gain media in the T+O bands. In this study, we use the high-quality broadband QD optical gain to develop a monolithically integrated QD optical gain modulator (QD-OGM) device that has a semiconductor optical amplifier (QD-SOA) for Gb/s-order highspeed optical data generation in the 1.3-μm waveband. The insertion loss of the device can be compensated through the SOA, and we obtained an optical gain change of up to ~7 dB in the OGM section. Further, we successfully demonstrate a 10-Gb/s clear eye opening using the QD-OGM/SOA device with a clock-data recovery sequence at the receiver end. These results suggest that the monolithic QD-EOM/SOA is suitable for increasing the number of wavelength channels for smart short-range communications.

  18. AFM diagnostics of graphene-based quantum Hall devices

    Czech Academy of Sciences Publication Activity Database

    Sikora, A.; Woszczyna, M.; Friedemann, M.; Ahlers, F. J.; Kalbáč, Martin

    2012-01-01

    Roč. 43, 2-3 (2012), s. 479-486 ISSN 0968-4328 Institutional research plan: CEZ:AV0Z40400503 Keywords : graphene * quantum Hall effect devices * atomic force microscopy Subject RIV: CG - Electrochemistry Impact factor: 1.876, year: 2012

  19. Coulomb blockade due to quantum phase slips illustrated with devices

    NARCIS (Netherlands)

    Hriscu, A.M.; Nazarov, Y.V.

    2011-01-01

    To illustrate the emergence of Coulomb blockade from coherent quantum phase-slip processes in thin superconducting wires, we propose and theoretically investigate two elementary setups, or devices. The setups are derived from the Cooper-pair box and Cooper-pair transistor, so we refer to them as the

  20. Quantum Devices Bonded Beneath a Superconducting Shield: Part 2

    Science.gov (United States)

    McRae, Corey Rae; Abdallah, Adel; Bejanin, Jeremy; Earnest, Carolyn; McConkey, Thomas; Pagel, Zachary; Mariantoni, Matteo

    The next-generation quantum computer will rely on physical quantum bits (qubits) organized into arrays to form error-robust logical qubits. In the superconducting quantum circuit implementation, this architecture will require the use of larger and larger chip sizes. In order for on-chip superconducting quantum computers to be scalable, various issues found in large chips must be addressed, including the suppression of box modes (due to the sample holder) and the suppression of slot modes (due to fractured ground planes). By bonding a metallized shield layer over a superconducting circuit using thin-film indium as a bonding agent, we have demonstrated proof of concept of an extensible circuit architecture that holds the key to the suppression of spurious modes. Microwave characterization of shielded transmission lines and measurement of superconducting resonators were compared to identical unshielded devices. The elimination of box modes was investigated, as well as bond characteristics including bond homogeneity and the presence of a superconducting connection.

  1. Experimental measurement-device-independent quantum digital signatures.

    Science.gov (United States)

    Roberts, G L; Lucamarini, M; Yuan, Z L; Dynes, J F; Comandar, L C; Sharpe, A W; Shields, A J; Curty, M; Puthoor, I V; Andersson, E

    2017-10-23

    The development of quantum networks will be paramount towards practical and secure telecommunications. These networks will need to sign and distribute information between many parties with information-theoretic security, requiring both quantum digital signatures (QDS) and quantum key distribution (QKD). Here, we introduce and experimentally realise a quantum network architecture, where the nodes are fully connected using a minimum amount of physical links. The central node of the network can act either as a totally untrusted relay, connecting the end users via the recently introduced measurement-device-independent (MDI)-QKD, or as a trusted recipient directly communicating with the end users via QKD. Using this network, we perform a proof-of-principle demonstration of QDS mediated by MDI-QKD. For that, we devised an efficient protocol to distil multiple signatures from the same block of data, thus reducing the statistical fluctuations in the sample and greatly enhancing the final QDS rate in the finite-size scenario.

  2. Memory-assisted measurement-device-independent quantum key distribution

    Science.gov (United States)

    Panayi, Christiana; Razavi, Mohsen; Ma, Xiongfeng; Lütkenhaus, Norbert

    2014-04-01

    A protocol with the potential of beating the existing distance records for conventional quantum key distribution (QKD) systems is proposed. It borrows ideas from quantum repeaters by using memories in the middle of the link, and that of measurement-device-independent QKD, which only requires optical source equipment at the user's end. For certain memories with short access times, our scheme allows a higher repetition rate than that of quantum repeaters with single-mode memories, thereby requiring lower coherence times. By accounting for various sources of nonideality, such as memory decoherence, dark counts, misalignment errors, and background noise, as well as timing issues with memories, we develop a mathematical framework within which we can compare QKD systems with and without memories. In particular, we show that with the state-of-the-art technology for quantum memories, it is potentially possible to devise memory-assisted QKD systems that, at certain distances of practical interest, outperform current QKD implementations.

  3. Evaluation of semiconductor devices for Electric and Hybrid Vehicle (EHV) ac-drive applications, volume 1

    Science.gov (United States)

    Lee, F. C.; Chen, D. Y.; Jovanovic, M.; Hopkins, D. C.

    1985-01-01

    The results of evaluation of power semiconductor devices for electric hybrid vehicle ac drive applications are summarized. Three types of power devices are evaluated in the effort: high power bipolar or Darlington transistors, power MOSFETs, and asymmetric silicon control rectifiers (ASCR). The Bipolar transistors, including discrete device and Darlington devices, range from 100 A to 400 A and from 400 V to 900 V. These devices are currently used as key switching elements inverters for ac motor drive applications. Power MOSFETs, on the other hand, are much smaller in current rating. For the 400 V device, the current rating is limited to 25 A. For the main drive of an electric vehicle, device paralleling is normally needed to achieve practical power level. For other electric vehicle (EV) related applications such as battery charger circuit, however, MOSFET is advantageous to other devices because of drive circuit simplicity and high frequency capability. Asymmetrical SCR is basically a SCR device and needs commutation circuit for turn off. However, the device poses several advantages, i.e., low conduction drop and low cost.

  4. Performance analysis of Arithmetic Mean method in determining peak junction temperature of semiconductor device

    Directory of Open Access Journals (Sweden)

    Mohana Sundaram Muthuvalu

    2015-12-01

    Full Text Available High reliability users of microelectronic devices have been derating junction temperature and other critical stress parameters to improve device reliability and extend operating life. The reliability of a semiconductor is determined by junction temperature. This paper gives a useful analysis on mathematical approach which can be implemented to predict temperature of a silicon die. The problem could be modeled as heat conduction equation. In this study, numerical approach based on implicit scheme and Arithmetic Mean (AM iterative method will be applied to solve the governing heat conduction equation. Numerical results are also included in order to assert the effectiveness of the proposed technique.

  5. Semiconductor device-based sensors for gas, chemical, and biomedical applications

    CERN Document Server

    Ren, Fan

    2011-01-01

    Sales of U.S. chemical sensors represent the largest segment of the multi-billion-dollar global sensor market, which includes instruments for chemical detection in gases and liquids, biosensors, and medical sensors. Although silicon-based devices have dominated the field, they are limited by their general inability to operate in harsh environments faced with factors such as high temperature and pressure. Exploring how and why these instruments have become a major player, Semiconductor Device-Based Sensors for Gas, Chemical, and Biomedical Applications presents the latest research, including or

  6. 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.

  7. The Influence of Surface Chemistry on the Optoelectronic Properties of Semiconductor Quantum Dots

    Science.gov (United States)

    Harris, Rachel Dory

    This dissertation describes the relationship between the surface chemistry of colloidal semiconductor nanocrystals (quantum dots, QDs) and their optoelectronic properties, such as photoluminescence and degree of quantum confinement. We primarily focus our efforts on one particular subset of ligands known to couple strongly to the inorganic core of the QD to decrease its quantum confinement, phenyldithiocarbamates (PTCs). We focus first on the development of quantitative Nuclear Magnetic Resonance (NMR) techniques to characterize the identity and quantity of ligands (such as PTCs and oleic acid) bound to nanocrystal surfaces. When we correlate the surface chemistry information obtained from NMR with the optical spectra of our QDs, we find that for strongly-delocalizing ligands like PTC, the spatial distribution of ligands on the QD surface affects the overall degree of delocalization. In the later chapters of this thesis, we describe two avenues for exploiting the relationship between surface coverage of exciton-delocalizing ligands and quantum confinement to design strongly coupled, hierarchical nanomaterials for efficient charge transport in films or in solution. We explore the treatment of thin lead sulfide QD films with a PTC derivative to improve their overall conductivity relative to benzoic acid, a similar molecule that does not affect confinement. Finally, we describe a potential strategy to improve the yield and rate of hole transfer to a tethered phthalocyanine molecule using dithiocarbamate and thiolate linkers.

  8. Frequency doubling of an InGaAs multiple quantum wells semiconductor disk laser

    Science.gov (United States)

    Lidan, Jiang; Renjiang, Zhu; Maohua, Jiang; Dingke, Zhang; Yuting, Cui; Peng, Zhang; Yanrong, Song

    2018-01-01

    We demonstrate a good beam quality 483 nm blue coherent radiation from a frequency doubled InGaAs multiple quantum wells semiconductor disk laser. The gain chip is consisted of 6 repeats of strain uncompensated InGaAs/GaAs quantum wells and 25 pairs of GaAs/AlAs distributed Bragg reflector. A 4 × 4 × 7 mm3 type I phase-matched BBO nonlinear crystal is used in a V-shaped laser cavity for the second harmonic generation, and 210 mW blue output power is obtained when the absorbed pump power is 3.5 W. The M2 factors of the laser beam in x and y directions are about 1.04 and 1.01, respectively. The output power of the blue laser is limited by the relatively small number of the multiple quantum wells, and higher power can be expected by increasing the number of the multiple quantum wells and improving the heat management of the laser.

  9. Piezoelectric and deformation potential effects of strain-dependent luminescence in semiconductor quantum well structures

    DEFF Research Database (Denmark)

    Zhang, Aihua; Peng, Mingzeng; Willatzen, Morten

    2017-01-01

    The mechanism of strain-dependent luminescence is important for the rational design of pressure-sensing devices. The interband momentum-matrix element is the key quantity for understanding luminescent phenomena. We analytically solved an infinite quantum well (IQW) model with strain...

  10. Mini array of quantum Hall devices based on epitaxial graphene

    Energy Technology Data Exchange (ETDEWEB)

    Novikov, S.; Lebedeva, N. [Department of Micro and Nanosciences, Aalto University, Micronova, Tietotie 3, Espoo (Finland); Hämäläinen, J.; Iisakka, I.; Immonen, P.; Manninen, A. J.; Satrapinski, A. [VTT Technical Research Centre of Finland Ltd., Centre for Metrology MIKES, P.O. Box 1000, 02044 VTT (Finland)

    2016-05-07

    Series connection of four quantum Hall effect (QHE) devices based on epitaxial graphene films was studied for realization of a quantum resistance standard with an up-scaled value. The tested devices showed quantum Hall plateaux R{sub H,2} at a filling factor v = 2 starting from a relatively low magnetic field (between 4 T and 5 T) when the temperature was 1.5 K. The precision measurements of quantized Hall resistance of four QHE devices connected by triple series connections and external bonding wires were done at B = 7 T and T = 1.5 K using a commercial precision resistance bridge with 50 μA current through the QHE device. The results showed that the deviation of the quantized Hall resistance of the series connection of four graphene-based QHE devices from the expected value of 4×R{sub H,2} = 2 h/e{sup 2} was smaller than the relative standard uncertainty of the measurement (<1 × 10{sup −7}) limited by the used resistance bridge.

  11. Frequency-Domain Thermal Modelling and Characterization of Power Semiconductor Devices

    DEFF Research Database (Denmark)

    Ma, Ke; He, Ning; Liserre, Marco

    2016-01-01

    their limits to correctly predict the device temperatures, especially when considering the thermal grease and heat sink attached to the power semiconductor devices. In this paper, frequency-domain approach is applied to the modelling of the thermal dynamics for power devices. The limits of the existing RC lump......The thermal behavior of power electronics devices has being a crucial design consideration because it is closely related to the reliability and also the cost of the converter system. Unfortunately, the widely used thermal models based on lumps of thermal resistances and capacitances have......-based thermal networks are explained from a point of view of frequency domain. Based on the discovery, a more advanced thermal model developed in the frequency domain is proposed, which can be easily established by characterizing the slope variation from the bode diagram of the typically used Foster thermal...

  12. Infrared studies of impurity states and ultrafast carrier dynamics in semiconductor quantum structures

    Energy Technology Data Exchange (ETDEWEB)

    Stehr, D.

    2007-12-28

    This thesis deals with infrared studies of impurity states, ultrafast carrier dynamics as well as coherent intersubband polarizations in semiconductor quantum structures such as quantum wells and superlattices, based on the GaAs/AlGaAs material system. In the first part it is shown that the 2p{sub z} confined impurity state of a semiconductor quantum well develops into an excited impurity band in the case of a superlattice. This is studied by following theoretically the transition from a single to a multiple quantum well or superlattice by exactly diagonalizing the three-dimensional Hamiltonian for a quantum well system with random impurities. These results also require reinterpretation of previous experimental data. The relaxation dynamics of interminiband transitions in doped GaAs/AlGaAs superlattices in the mid-IR are studied. This involves single-color pump-probe measurements to explore the dynamics at different wavelengths, which is performed with the Rossendorf freeelectron laser (FEL), providing picosecond pulses in a range from 3-200 {mu}m and are used for the first time within this thesis. In these experiments, a fast bleaching of the interminiband transition is observed followed by thermalization and subsequent relaxation, whose time constants are determined to be 1-2 picoseconds. This is followed by an additional component due to carrier cooling in the lower miniband. In the second part, two-color pump-probe measurements are performed, involving the FEL as the pump source and a table-top broad-band tunable THz source for probing the transmission changes. In addition, the dynamics of excited electrons within the minibands is explored and their contribution quantitatively extracted from the measurements. Intersubband absorption experiments of photoexcited carriers in single quantum well structures, measured directly in the time-domain, i.e. probing coherently the polarization between the first and the second subband, are presented. By varying the carrier

  13. Novel Photovoltaic Devices Using Ferroelectric Material and Colloidal Quantum Dots

    Science.gov (United States)

    Paik, Young Hun

    As the global concern for the financial and environmental costs of traditional energy resources increases, research on renewable energy, most notably solar energy, has taken center stage. Many alternative photovoltaic (PV) technologies for 'the next generation solar cell' have been extensively studied to overcome the Shockley-Queisser 31% efficiency limit as well as tackle the efficiency vs. cost issues. This dissertation focuses on the novel photovoltaic mechanism for the next generation solar cells using two inorganic nanomaterials, nanocrystal quantum dots and ferroelectric nanoparticles. Lead zirconate titanate (PZT) materials are widely studied and easy to synthesize using solution based chemistry. One of the fascinating properties of the PZT material is a Bulk Photovoltaic effect (BPVE). This property has been spotlighted because it can produce very high open circuit voltage regardless of the electrical bandgap of the materials. However, the poor optical absorption of the PZT materials and the required high temperature to form the ferroelectric crystalline structure have been obstacles to fabricate efficient photovoltaic devices. Colloidal quantum dots also have fascinating optical and electrical properties such as tailored absorption spectrum, capability of the bandgap engineering due to the wide range of material selection and quantum confinement, and very efficient carrier dynamics called multiple exciton generations. In order to utilize these properties, many researchers have put numerous efforts in colloidal quantum dot photovoltaic research and there has been remarkable progress in the past decade. However, several drawbacks are still remaining to achieve highly efficient photovoltaic device. Traps created on the large surface area, low carrier mobility, and lower open circuit voltage while increasing the absorption of the solar spectrum is main issues of the nanocrystal based photovoltaic effect. To address these issues and to take the advantages of

  14. SCOOP - Semiconductor COmponents for Optical signal Processing

    DEFF Research Database (Denmark)

    Mørk, Jesper; Yvind, Kresten; Oxenløwe, Leif Katsuo

    2001-01-01

    Opto-electronic semiconductor devices operating at very high bitrates play a central role in the continued expansion of the transmission capacity of optical communication systems. A number of different devices based on quantum well structures have been manufactured within the framework of the nat......Opto-electronic semiconductor devices operating at very high bitrates play a central role in the continued expansion of the transmission capacity of optical communication systems. A number of different devices based on quantum well structures have been manufactured within the framework...

  15. Direct CVD Graphene Growth on Semiconductors and Dielectrics for Transfer-Free Device Fabrication.

    Science.gov (United States)

    Wang, Huaping; Yu, Gui

    2016-07-01

    Graphene is the most broadly discussed and studied two-dimensional material because of its preeminent physical, mechanical, optical, and thermal properties. Until now, metal-catalyzed chemical vapor deposition (CVD) has been widely employed for the scalable production of high-quality graphene. However, in order to incorporate the graphene into electronic devices, a transfer process from metal substrates to targeted substrates is inevitable. This process usually results in contamination, wrinkling, and breakage of graphene samples - undesirable in graphene-based technology and not compatible with industrial production. Therefore, direct graphene growth on desired semiconductor and dielectric substrates is considered as an effective alternative. Over the past years, there have been intensive investigations to realize direct graphene growth using CVD methods without the catalytic role of metals. Owing to the low catalytic activity of non-metal substrates for carbon precursor decomposition and graphene growth, several strategies have been designed to facilitate and engineer graphene fabrication on semiconductors and insulators. Here, those developed strategies for direct CVD graphene growth on semiconductors and dielectrics for transfer-free fabrication of electronic devices are reviewed. By employing these methods, various graphene-related structures can be directly prepared on desired substrates and exhibit excellent performance, providing versatile routes for varied graphene-based materials fabrication. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. Quantum dot lasers: From promise to high-performance devices

    Science.gov (United States)

    Bhattacharya, P.; Mi, Z.; Yang, J.; Basu, D.; Saha, D.

    2009-03-01

    Ever since self-organized In(Ga)As/Ga(AI)As quantum dots were realized by molecular beam epitaxy, it became evident that these coherently strained nanostructures could be used as the active media in devices. While the expected advantages stemming from three-dimensional quantum confinement were clearly outlined, these were not borne out by the early experiments. It took a very detailed understanding of the unique carrier dynamics in the quantum dots to exploit their full potential. As a result, we now have lasers with emission wavelengths ranging from 0.7 to 1.54 μm, on GaAs, which demonstrate ultra-low threshold currents, near-zero chip and α-factor and large modulation bandwidth. State-of-the-art performance characteristics of these lasers are briefly reviewed. The growth, fabrication and characteristics of quantum dot lasers on silicon substrates are also described. With the incorporation of multiple quantum dot layers as a dislocation filter, we demonstrate lasers with Jth=900 A/cm 2. The monolithic integration of the lasers with guided wave modulators on silicon is also described. Finally, the properties of spin-polarized lasers with quantum dot active regions are described. Spin injection of electrons is done with a MnAs/GaAs tunnel barrier. Laser operation at 200 K is demonstrated, with the possibility of room temperature operation in the near future.

  17. Quantum size effects on spin-transfer torque in a double barrier magnetic tunnel junction with a nonmagnetic-metal (semiconductor) spacer

    International Nuclear Information System (INIS)

    Daqiq, Reza; Ghobadi, Nader

    2016-01-01

    We study the quantum size effects of an MgO-based double barrier magnetic tunnel junction with a nonmagnetic-metal (DBMTJ-NM) (semiconductor (DBMTJ-SC)) spacer on the charge current and the spin-transfer torque (STT) components using non-equilibrium Green's function (NEGF) formalism. The results show oscillatory behavior due to the resonant tunneling effect depending on the structure parameters. We find that the charge current and the STT components in the DBMTJ-SC demonstrate the magnitude enhancement in comparison with the DBMTJ-NM. The bias dependence of the STT components in a DBMTJ-NM shows different behavior in comparison with spin valves and conventional MTJs. Therefore, by choosing a specific SC spacer with suitable thickness in a DBMTJ the charge current and the STT components significantly increase so that one can design a device with high STT and faster magnetization switching. - Highlights: • The quantum size effects are studied in double barrier magnetic tunnel junctions. • Spin torque (ST) components oscillate for increasing of middle spacer thicknesses. • Due to the resonant tunneling in the quantum well, oscillations have appeared. • By replacement a metal spacer with a semiconductor (ZnO) ST has increased. • The ST components vs. bias show gradually decreasing unlike spin valves or MTJs.

  18. Memory effects in a Al/Ti:HfO2/CuPc metal-oxide-semiconductor device

    Science.gov (United States)

    Tripathi, Udbhav; Kaur, Ramneek

    2016-05-01

    Metal oxide semiconductor structured organic memory device has been successfully fabricated. Ti doped hafnium oxide (Ti:HfO2) nanoparticles has been fabricated by precipitation method and further calcinated at 800 °C. Copper phthalocyanine, a hole transporting material has been utilized as an organic semiconductor. The electrical properties of the fabricated device have been studied by measuring the current-voltage and capacitance-voltage characteristics. The amount of charge stored in the nanoparticles has been calculated by using flat band condition. This simple approach for fabricating MOS memory device has opens up opportunities for the development of next generation memory devices.

  19. Modeling of semiconductor devices for high-speed all-optical signal processing

    DEFF Research Database (Denmark)

    Bischoff, Svend; Højfeldt, Sune; Mørk, Jesper

    2001-01-01

    The all-optical signal processing performance of devices based on active semiconductor waveguides is investigated. A large signal model is used to analyse the physical mechanisms limiting the high-speed performance of both semiconductor optical amplifiers (SOAs) and electro-absorption modulators...... (EAMs). Wavelength conversion and signal regeneration in EAMs is discussed at 10 and 40 Gbit/s. The finite carrier sweep-out time is shown to limit the EAM performance. Four-wave mixing (FWM) in SOAs is almost instantaneous. However, with increasing bit rates and advanced processing functionalities some...... limitations arise. These limitations are elucidated by studying bi-directional simultaneous clear and drop (de-multiplexing) for a 4x40 Gbit/s signal. The simultaneous clearing and de-multiplexing (drop) of an optical time division multiplexing signal channel for an 8x40 Gbit/s signal is investigated...

  20. Modeling of semiconductor devices for high-speed all-optical signal processing

    DEFF Research Database (Denmark)

    Bischoff, Svend; Højfeldt, Sune; Mørk, Jesper

    2001-01-01

    limitations arise. These limitations are elucidated by studying bi-directional simultaneous clear and drop (de-multiplexing) for a 4x40 Gbit/s signal. The simultaneous clearing and de-multiplexing (drop) of an optical time division multiplexing signal channel for an 8x40 Gbit/s signal is investigated......The all-optical signal processing performance of devices based on active semiconductor waveguides is investigated. A large signal model is used to analyse the physical mechanisms limiting the high-speed performance of both semiconductor optical amplifiers (SOAs) and electro-absorption modulators...... (EAMs). Wavelength conversion and signal regeneration in EAMs is discussed at 10 and 40 Gbit/s. The finite carrier sweep-out time is shown to limit the EAM performance. Four-wave mixing (FWM) in SOAs is almost instantaneous. However, with increasing bit rates and advanced processing functionalities some...

  1. Solution manufacturing of 2D piezoelectric semiconductors for smart wearable devices

    Science.gov (United States)

    Wang, Yixiu; Qiu, Gang; Ye, Peide; Wu, Wenzhuo

    Due to two-dimensional (2D) nanomaterials, such as graphene and transition metal dichalcogenide (TMD) nanosheets, with single- or few-layer thickness have shown some extraordinary properties in contrast to their bulk counter parts. For example, some of the 2D nanomaterials exhibit layer-dependent bandgap. Besides, the high flexibility, ultrahigh surface area and good mechanical strength make them promising for electronics/optoelectronics and sensors. Here, we report a low-temperature, solution-based method to produce a new class of 2D piezoelectric semiconductors with controlled thickness and lateral dimensions at large scale. Such material shows non-centrosymmetric crystal structure, which enable us to not only explore its basic piezoelectric and semiconductor properties but also its application in wearable devices.

  2. Determination of charge transport activation energy and injection barrier in organic semiconductor devices

    Science.gov (United States)

    Züfle, S.; Altazin, S.; Hofmann, A.; Jäger, L.; Neukom, M. T.; Brütting, W.; Ruhstaller, B.

    2017-09-01

    Charge carrier transport in organic semiconductor devices is thermally activated with characteristic activation energies in the range of 0.2-0.6 eV, leading to strongly temperature-dependent behaviour. For designing efficient organic semiconductor materials and devices, it is therefore indispensable to understand the origin of these activation energies. We propose that in bilayer organic light-emitting diodes (OLEDs) employing a polar electron transport layer, as well as in metal-insulator-semiconductor (MIS) devices, the hole injection barrier Einj and the hole mobility activation energy Eμ can be decoupled from each other if temperature-dependent capacitance-frequency (C-f-T) and MIS-CELIV (charge extraction by linearly increasing voltage) experiments are combined. While the C-f-T signal contains information of both injection and transport, the CELIV current is expected to be insensitive to the electrode injection properties. We employ numerical drift-diffusion simulations to investigate the accuracy of this analytical parameter extraction approach and to develop criteria for its validity. We show that the implicit assumption of constant charge density and field profiles leads to systematic errors in determining the activation energies. Thus, one should be aware of the intrinsic limitations of the analytical Arrhenius fit, and for more accurate parameter determination a full drift-diffusion modelling is advised. Applying the analytical method to a standard bilayer OLED, we find that the total activation energy of 0.5 eV for the hole current can be split into contributions of ≈0.25 eV each for injection barrier and mobility. Finally, we also discuss the broader applicability of this method for other device stacks and material combinations.

  3. Resonances in superconducting quantum interference devices: SQUID's

    International Nuclear Information System (INIS)

    Faris, S.M.; Valsamakis, E.A.

    1981-01-01

    Resonances in asymmetric two junction SQUID's are analyzed. The distinction between current-controlled and voltage-controlled cases is found to be crucial to the full understanding of the device dynamics. In the current-controlled case, three modes of oscillation are predicted at frequencies [(L 1 +L 2 )C 1 ]/sup -1/2/, [(L 1 +L 2 )C 2 ]/sup -1/2/, and [(L 1 +L 2 )C 1 +C 2 /(C 1 +C 2 )]/sup -1/2/, and confirmed experimentally. In the voltage-controlled case only two modes are predicted at frequencies (L 1 C 1 )/sup -1/2/ and (L 2 C 2 )/sup -1/2/, which in practice are difficult to observe. We show that such a distinction leads to a better interpretation of experimental observations

  4. Charge Carrier Dynamics of Quantum Confined Semiconductor Nanoparticles Analyzed via Transient Absorption Spectroscopy

    Science.gov (United States)

    Thibert, Arthur Joseph, III

    Semiconductor nanoparticles are tiny crystalline structures (typically range from 1 - 100 nm) whose shape in many cases can be dictated through tailored chemical synthesis with atomic scale precision. The small size of these nanoparticles often results in quantum confinement (spatial confinement of wave functions), which imparts the ability to manipulate band-gap energies thus allowing them to be optimally engineered for different applications (i.e., photovoltaics, photocatalysis, imaging). However, charge carriers excited within these nanoparticles are often involved in many different processes: trapping, trap migration, Auger recombination, non-radiative relaxation, radiative relaxation, oxidation / reduction, or multiple exciton generation. Broadband ultrafast transient absorption laser spectroscopy is used to spectrally resolve the fate of excited charge carriers in both wavelength and time, providing insight as to what synthetic developments or operating conditions will be necessary to optimize their efficiency for certain applications. This thesis outlines the effort of resolving the dynamics of excited charge carriers for several Cd and Si based nanoparticle systems using this experimental technique. The thesis is organized into five chapters and two appendices as indicated below. Chapter 1 provides a brief introduction to the photophysics of semiconductor nanoparticles. It begins by defining what nanoparticles, semiconductors, charge carriers, and quantum confinement are. From there it details how the study of charge carrier dynamics within nanoparticles can lead to increased efficiency in applications such as photocatalysis. Finally, the experimental methodology associated with ultrafast transient absorption spectroscopy is introduced and its power in mapping charge carrier dynamics is established. Chapter 2 (JPCC, 19647, 2011) introduces the first of the studied samples: water-solubilized 2D CdSe nanoribbons (NRs), which were synthesized in the Osterloh

  5. A gate defined quantum dot on the two-dimensional transition metal dichalcogenide semiconductor WSe2

    Science.gov (United States)

    Song, Xiang-Xiang; Liu, Di; Mosallanejad, Vahid; You, Jie; Han, Tian-Yi; Chen, Dian-Teng; Li, Hai-Ou; Cao, Gang; Xiao, Ming; Guo, Guang-Can; Guo, Guo-Ping

    2015-10-01

    Two-dimensional layered materials, such as transition metal dichalcogenides (TMDCs), are promising materials for future electronics owing to their unique electronic properties. With the presence of a band gap, atomically thin gate defined quantum dots (QDs) can be achieved on TMDCs. Herein, standard semiconductor fabrication techniques are used to demonstrate quantum confined structures on WSe2 with tunnel barriers defined by electric fields, therefore eliminating the edge states induced by etching steps, which commonly appear in gapless graphene QDs. Over 40 consecutive Coulomb diamonds with a charging energy of approximately 2 meV were observed, showing the formation of a QD, which is consistent with the simulations. The size of the QD could be tuned over a factor of 2 by changing the voltages applied to the top gates. These results shed light on a way to obtain smaller quantum dots on TMDCs with the same top gate geometry compared to traditional GaAs/AlGaAs heterostructures with further research.

  6. Intermediate-band photosensitive device with quantum dots having tunneling barrier embedded in organic matrix

    Science.gov (United States)

    Forrest, Stephen R.

    2008-08-19

    A plurality of quantum dots each have a shell. The quantum dots are embedded in an organic matrix. At least the quantum dots and the organic matrix are photoconductive semiconductors. The shell of each quantum dot is arranged as a tunneling barrier to require a charge carrier (an electron or a hole) at a base of the tunneling barrier in the organic matrix to perform quantum mechanical tunneling to reach the respective quantum dot. A first quantum state in each quantum dot is between a lowest unoccupied molecular orbital (LUMO) and a highest occupied molecular orbital (HOMO) of the organic matrix. Wave functions of the first quantum state of the plurality of quantum dots may overlap to form an intermediate band.

  7. Theoretical and experimental study of the effects of a ionizing pulse in semiconductor devices

    International Nuclear Information System (INIS)

    1970-01-01

    A semiconductor device exposed to a penetrating ionizing radiation is passed through by a transitory current, or photocurrent, that may disturb the operation of the device. Especially in the case of a nuclear explosion, the devices put at one kilometer from the location of the event, are submitted to a γ ray burst of a few tenths of nanoseconds with a dose rate of about 10 11 rad(Si)s. As there is no possibility of reaching dose rates upper than 10 10 Rad(Si)s using a pulsed γ irradiation in the laboratory, the very high dose rates were obtained using a pulsed laser, with a doped Nd glass head intended for silicon study. Results obtained are concerned with diodes, or bipolar and MOS transistors irradiated with both γ and laser pulse radiations. The dependence of the photocurrent response on the dose rate, and surface and bulk properties is emphasized [fr

  8. NATO Advanced Study Institute on Nondestructive Evaluation of Semiconductor Materials and Devices

    CERN Document Server

    1979-01-01

    From September 19-29, a NATO Advanced Study Institute on Non­ destructive Evaluation of Semiconductor Materials and Devices was held at the Villa Tuscolano in Frascati, Italy. A total of 80 attendees and lecturers participated in the program which covered many of the important topics in this field. The subject matter was divided to emphasize the following different types of problems: electrical measurements; acoustic measurements; scanning techniques; optical methods; backscatter methods; x-ray observations; accele­ rated life tests. It would be difficult to give a full discussion of such an Institute without going through the major points of each speaker. Clearly this is the proper task of the eventual readers of these Proceedings. Instead, it would be preferable to stress some general issues. What came through very clearly is that the measurements of the basic scientists in materials and device phenomena are of sub­ stantial immediate concern to the device technologies and end users.

  9. Relaxation of a kinetic hole due to carrier-carrier scattering in multisubband single-quantum-well semiconductors

    DEFF Research Database (Denmark)

    Dery, H.; Tromborg, Bjarne; Eisenstein, G.

    2003-01-01

    We describe a theoretical model for carrier-carrier scattering in an inverted semiconductor quantum well structure using a multisubband diagram. The model includes all possible nonvanishing interaction terms within the static screening approximation, and it enables one to calculate accurately...

  10. Statistical analysis of time-resolved emission from ensembles of semiconductor quantum dots: interpretations of exponantial decay models

    NARCIS (Netherlands)

    van Driel, A.F.; Nikolaev, I.; Vergeer, P.; Lodahl, P.; Vanmaekelbergh, D.; Vos, Willem L.

    2007-01-01

    We present a statistical analysis of time-resolved spontaneous emission decay curves from ensembles of emitters, such as semiconductor quantum dots, with the aim of interpreting ubiquitous non-single-exponential decay. Contrary to what is widely assumed, the density of excited emitters and the

  11. Fundamentals and Applications of Semiconductor Nanocrystals : A study on the synthesis, optical properties, and interactions of quantum dots

    NARCIS (Netherlands)

    Koole, R.

    2008-01-01

    This thesis focuses on both the fundamental aspects as well as applications of colloidal semiconductor nanocrystals, also called quantum dots (QDs). Due to the unique size-dependent optical and electronic properties of QDs, they hold great promise for a wide range of applications like solar cells,

  12. Security of Device-Independent Quantum Key Distribution in the Bounded-Quantum-Storage Model

    Directory of Open Access Journals (Sweden)

    S. Pironio

    2013-08-01

    Full Text Available Device-independent quantum key distribution (DIQKD is a formalism that supersedes traditional quantum key distribution, as its security does not rely on any detailed modeling of the internal working of the devices. This strong form of security is only possible using devices producing correlations that violate a Bell inequality. Full security proofs of DIQKD have recently been reported, but they tolerate zero or small amounts of noise and are restricted to protocols based on specific Bell inequalities. Here, we provide a security proof of DIQKD that is both more efficient and noise resistant, and also more general, as it applies to protocols based on arbitrary Bell inequalities and can be adapted to cover supraquantum eavesdroppers limited by the no-signaling principle only. It is formulated, however, in the bounded-quantum-storage model, where an upper bound on the adversary’s quantum memory is a priori known. This condition is not a limitation at present, since the best existing quantum memories have very short coherence times.

  13. A multiscale quantum mechanics/electromagnetics method for device simulations.

    Science.gov (United States)

    Yam, ChiYung; Meng, Lingyi; Zhang, Yu; Chen, GuanHua

    2015-04-07

    Multiscale modeling has become a popular tool for research applying to different areas including materials science, microelectronics, biology, chemistry, etc. In this tutorial review, we describe a newly developed multiscale computational method, incorporating quantum mechanics into electronic device modeling with the electromagnetic environment included through classical electrodynamics. In the quantum mechanics/electromagnetics (QM/EM) method, the regions of the system where active electron scattering processes take place are treated quantum mechanically, while the surroundings are described by Maxwell's equations and a semiclassical drift-diffusion model. The QM model and the EM model are solved, respectively, in different regions of the system in a self-consistent manner. Potential distributions and current densities at the interface between QM and EM regions are employed as the boundary conditions for the quantum mechanical and electromagnetic simulations, respectively. The method is illustrated in the simulation of several realistic systems. In the case of junctionless field-effect transistors, transfer characteristics are obtained and a good agreement between experiments and simulations is achieved. Optical properties of a tandem photovoltaic cell are studied and the simulations demonstrate that multiple QM regions are coupled through the classical EM model. Finally, the study of a carbon nanotube-based molecular device shows the accuracy and efficiency of the QM/EM method.

  14. Manipulating the Flow of Thermal Noise in Quantum Devices

    Science.gov (United States)

    Barzanjeh, Shabir; Aquilina, Matteo; Xuereb, André

    2018-02-01

    There has been significant interest recently in using complex quantum systems to create effective nonreciprocal dynamics. Proposals have been put forward for the realization of artificial magnetic fields for photons and phonons; experimental progress is fast making these proposals a reality. Much work has concentrated on the use of such systems for controlling the flow of signals, e.g., to create isolators or directional amplifiers for optical signals. In this Letter, we build on this work but move in a different direction. We develop the theory of and discuss a potential realization for the controllable flow of thermal noise in quantum systems. We demonstrate theoretically that the unidirectional flow of thermal noise is possible within quantum cascaded systems. Viewing an optomechanical platform as a cascaded system we show here that one can ultimately control the direction of the flow of thermal noise. By appropriately engineering the mechanical resonator, which acts as an artificial reservoir, the flow of thermal noise can be constrained to a desired direction, yielding a thermal rectifier. The proposed quantum thermal noise rectifier could potentially be used to develop devices such as a thermal modulator, a thermal router, and a thermal amplifier for nanoelectronic devices and superconducting circuits.

  15. Radiation effects on semiconductor devices in high energy heavy ion accelerators

    Energy Technology Data Exchange (ETDEWEB)

    Belousov, Anton

    2014-10-20

    Radiation effects on semiconductor devices in GSI Helmholtz Center for Heavy Ion Research are becoming more and more significant with the increase of beam intensity due to upgrades. Moreover a new accelerator is being constructed on the basis of GSI within the project of facility for antiproton and ion research (FAIR). Beam intensities will be increased by factor of 100 and energies by factor of 10. Radiation fields in the vicinity of beam lines will increase more than 2 orders of magnitude and so will the effects on semiconductor devices. It is necessary to carry out a study of radiation effects on semiconductor devices considering specific properties of radiation typical for high energy heavy ion accelerators. Radiation effects on electronics in accelerator environment may be divided into two categories: short-term temporary effects and long-term permanent degradation. Both may become critical for proper operation of some electronic devices. This study is focused on radiation damage to CCD cameras in radiation environment of heavy ion accelerator. Series of experiments with irradiation of devices under test (DUTs) by secondary particles produced during ion beam losses were done for this study. Monte Carlo calculations were performed to simulate the experiment conditions and conditions expected in future accelerator. Corresponding comparisons and conclusions were done. Another device typical for accelerator facilities - industrial Ethernet switch was tested in similar conditions during this study. Series of direct irradiations of CCD and MOS transistors with heavy ion beams were done as well. Typical energies of the primary ion beams were 0.5-1 GeV/u. Ion species: from Na to U. Intensities of the beam up to 10{sup 9} ions/spill with spill length of 200-300 ns. Criteria of reliability and lifetime of DUTs in specific radiation conditions were formulated, basing on experimental results of the study. Predictions of electronic device reliability and lifetime were

  16. Innovative Ge Quantum Dot Functional Sensing/Metrology Devices

    Science.gov (United States)

    2015-05-20

    International Electron Devices and Materials Symposium (IEDMS), Haulien, Taiwan. (Nov19-21, 2014) (9) Wei-Ting Lai, Kuo-Ching Yang, Ting- Chia Hsu, Po...International Conference on Solid-State Devices and Materials, Tsukuba, Japan (Sep. 8-11, 2014). (12) Wei-Ting Lai, Kuo-Ching Yang, Ting- Chia Hsu, Po...Ting- Chia Hsu, Tzu-Hsuan Cheng, Tzu-Min Hsu, and Pei-Wen Li, 2014, ”Size Tunable Strain and Interfacial Engineering of Germanium Quantum Dots,” 2014

  17. Fault localization and analysis in semiconductor devices with optical-feedback infrared confocal microscopy

    International Nuclear Information System (INIS)

    Sarmiento, Raymund; Cemine, Vernon Julius; Tagaca, Imee Rose; Salvador, Arnel; Mar Blanca, Carlo; Saloma, Caesar

    2007-01-01

    We report on a cost-effective optical setup for characterizing light-emitting semiconductor devices with optical-feedback confocal infrared microscopy and optical beam-induced resistance change.We utilize the focused beam from an infrared laser diode to induce local thermal resistance changes across the surface of a biased integrated circuit (IC) sample. Variations in the multiple current paths are mapped by scanning the IC across the focused beam. The high-contrast current maps allow accurate differentiation of the functional and defective sites, or the isolation of the surface-emittingp-i-n devices in the IC. Optical beam-induced current (OBIC) is not generated since the incident beam energy is lower than the bandgap energy of the p-i-n device. Inhomogeneous current distributions in the IC become apparent without the strong OBIC background. They are located at a diffraction-limited resolution by referencing the current maps against the confocal reflectance image that is simultaneously acquired via optical-feedback detection. Our technique permits the accurate identification of metal and semiconductor sites as well as the classification of different metallic structures according to thickness, composition, or spatial inhomogeneity

  18. Differential-phase-shift quantum key distribution experiment using fast physical random bit generator with chaotic semiconductor lasers.

    Science.gov (United States)

    Honjo, Toshimori; Uchida, Atsushi; Amano, Kazuya; Hirano, Kunihito; Someya, Hiroyuki; Okumura, Haruka; Yoshimura, Kazuyuki; Davis, Peter; Tokura, Yasuhiro

    2009-05-25

    A high speed physical random bit generator is applied for the first time to a gigahertz clocked quantum key distribution system. Random phase-modulation in a differential-phase-shift quantum key distribution (DPS-QKD) system is performed using a 1-Gbps random bit signal which is generated by a physical random bit generator with chaotic semiconductor lasers. Stable operation is demonstrated for over one hour, and sifted keys are successfully generated at a rate of 9.0 kbps with a quantum bit error rate of 3.2% after 25-km fiber transmission.

  19. Evaluation of dosimetric parameters of a commercial semiconductor device in computed tomography

    Energy Technology Data Exchange (ETDEWEB)

    Magalhaes, C. M. S.; Sobrinho, M. C.; Souza, D. N. [Departmento de Fisica, Universidade Federale de Sergipe, Av. Marechal Rondon s/n, 49.100-000, Rosa Elze, Sao Cristovao-SE (Brazil); Santos, L. A. P. [Laboratorio de Instrumentacao Nuclear, Centro Regional de Ciencias Nucleares, Av. Professor Luiz Freire, 200, 50.740-540 Recife-PE (Brazil)

    2009-10-15

    Semiconductor devices have been widely used for dosimetry in radiotherapy and more recently in diagnostic radiology. In order to evaluate the performance of a phototransistor as a radiation detector in computed tomography (CT), some dosimetric parameters were evaluated, such as: repetitive, angular dependence, response for different tube potentials, dose and dose rate dependence. The irradiation was performed with the detector on the axis of rotation of a X-ray tube in CT scanner. The results showed that, making the necessary corrections, it is possible to use the phototransistor for dosimetry in tomography. (Author)

  20. Micro and nanophotonics for semiconductor infrared detectors towards an ultimate uncooled device

    CERN Document Server

    Jakšic, Zoran

    2014-01-01

    The advent of microelectromechanic system (MEMS) technologies and nanotechnologies has resulted in a multitude of structures and devices with ultra compact dimensions and with vastly enhanced or even completely novel properties. In the field of photonics it resulted in the appearance of new paradigms, including photonic crystals that exhibit photonic bandgap and represent an optical analog of semiconductors and metamaterials that have subwavelength features and may have almost arbitrary values of effective refractive index, including those below zero. In addition to that, a whole new field of

  1. Environmental conditions effect on characteristics of some unijunction and bijunction semiconductor devices

    Science.gov (United States)

    Kamh, Sanaa A.; Soliman, F. A. S.

    2006-08-01

    This paper is an attempt to shed further light on the investigation of radiation effect on unijunction and bijunction semiconductor devices. The radiation damage in silicon bipolar junction transistor (BJT) and solar cell is analyzed experimentally and theoretically using computer programming. It was found that for low-frequency transistors, 90% of the damage in forward current gain occurs at low gamma-doses, around 100 krad. For solar cells, the radiation damage is attributed mainly to the change in the lifetime of minority carriers contained in the base region, which depends on both radiation fluence and energy, as well as the solar cell structure.

  2. Evaluation of pelletron accelerator facility to study radiation effects on semiconductor devices

    Science.gov (United States)

    Prakash, A. P. Gnana; Pushpa, N.; Praveen, K. C.; Naik, P. S.; Revannasiddaiah, D.

    2012-06-01

    In this paper we present the comprehensive results on the effects of different radiation on the electrical characteristics of different semiconductor devices like Si BJT, n-channel MOSFETs, 50 GHz and 200 GHz silicon-germanium heterojunction bipolar transistor (SiGe HBTs). The total dose effects of different radiation are compared in the same total dose ranging from 100 krad to 100 Mrad. We show that the irradiation time needed to reach very high total dose can be reduced by using Pelletron accelerator facilities instead of conventional irradiation facilities.

  3. Evaluation of pelletron accelerator facility to study radiation effects on semiconductor devices

    Energy Technology Data Exchange (ETDEWEB)

    Prakash, A. P. Gnana; Pushpa, N.; Praveen, K. C.; Naik, P. S.; Revannasiddaiah, D. [Department of Studies in Physics, University of Mysore, Manasagangotri, Mysore-570006, Karnataka (India)

    2012-06-05

    In this paper we present the comprehensive results on the effects of different radiation on the electrical characteristics of different semiconductor devices like Si BJT, n-channel MOSFETs, 50 GHz and 200 GHz silicon-germanium heterojunction bipolar transistor (SiGe HBTs). The total dose effects of different radiation are compared in the same total dose ranging from 100 krad to 100 Mrad. We show that the irradiation time needed to reach very high total dose can be reduced by using Pelletron accelerator facilities instead of conventional irradiation facilities.

  4. Spin Manipulation through geometric phase in III-V semiconductor quantum dots

    Science.gov (United States)

    Prbahakar, Sanjay; Melnik, Roderick

    2015-03-01

    A more robust technique is proposed to flip the spin completely through geometric phase in III-V semiconductor quantum dots (QDs). We transport the QDs adiabatically in a closed loop along the circular trajectory in the plane of two dimensional electron gas with the application of time dependent gate controlled electric fields and investigate the manipulation of Berry phase with the spin-orbit couplings. Here we show that both the Rashba and the Dresselhaus couplings are present for inducing a phase necessary for spin flip. If one of them is absent, the induced phase is trivial and irrelevant for spin-flip (Phys. Rev. B 89, 245310 (2014), Applied Physics Letters 104, 142411 (2014)). We acknowledge the funding agency: Natural Sciences and Engineering Research Council of Canada and Canada Research Chair Program.

  5. Nonlinear optics response of semiconductor quantum wells under high magnetic fields

    International Nuclear Information System (INIS)

    Chemla, D.S.

    1993-07-01

    Recent investigations on the nonlinear optical response of semiconductor quantum wells in a strong perpendicular magnetic field, H, are reviewed. After some introductory material the evolution of the linear optical properties of GaAs QW's as a function of H is discussed; an examination is made of how the magneto-excitons (MX) extrapolate continuously between quasi-2D QW excitons (X) when H = 0, and pairs of Landau levels (LL) when H → ∞. Next, femtosecond time resolved investigations of their nonlinear optical response are presented; the evolution of MX-MX interactions with increasing H is stressed. Finally, how, as the dimensionality is reduced by application of H, the number of scattering channels is limited and relaxation of electron-hole pairs is affected. How nonlinear optical spectroscopy can be exploited to access the relaxation of angular momentum within magneto-excitons is also discussed

  6. Coherent manipulation of spontaneous emission spectra in coupled semiconductor quantum well structures.

    Science.gov (United States)

    Chen, Aixi

    2014-11-03

    In triple coupled semiconductor quantum well structures (SQWs) interacting with a coherent driving filed, a coherent coupling field and a weak probe field, spontaneous emission spectra are investigated. Our studies show emission spectra can easily be manipulated through changing the intensity of the driving and coupling field, detuning of the driving field. Some interesting physical phenomena such as spectral-line enhancement/suppression, spectral-line narrowing and spontaneous emission quenching may be obtained in our system. The theoretical studies of spontaneous emission spectra in SQWS have potential application in high-precision spectroscopy. Our studies are based on the real physical system [Appl. Phys. Lett.86(20), 201112 (2005)], and this scheme might be realizable with presently available techniques.

  7. Plasmon-enhanced second harmonic generation in semiconductor quantum dots close to metal nanoparticles

    Directory of Open Access Journals (Sweden)

    Andrea V. Bragas

    2011-03-01

    Full Text Available We report the enhancement of the optical second harmonic signal in non-centrosymmetric semiconductor CdS quantum dots, when they are placed in close contact with isolated silver nanoparticles. The intensity enhancement is about 1000. We also show that the enhancement increases when the incoming laser frequency $omega$ is tuned toward the spectral position of the silver plasmon at $2omega$, proving that the silver nanoparticle modifies the nonlinear emission.Received: 8 March 2011, Accepted: 30 May 2011; Edited by: L. Viña; Reviewed by: R. Gordon, Department of Electrical and Computer Engineering, University of Victoria, British Columbia, Canada; DOI: 10.4279/PIP.030002Cite as: P. M. Jais, C. von Bilderling, A. V. Bragas, Papers in Physics 3, 030002 (2011

  8. High-order sideband generation in a semiconductor quantum well driven by two orthogonal terahertz fields

    Science.gov (United States)

    Yan, Jie-Yun

    2017-08-01

    The theory of excitonic high-order sideband generation (HSG) in a semiconductor quantum well irradiated by two orthogonal terahertz (THz) fields (one frequency is an integral multiple of the other) is presented. The exact analytical solution to the sideband spectrum is given with the help of the generalized Bessel functions. As a special case, the HSG when the frequencies of these two THz fields are the same is derived and its dependence on the ellipticity of the THz field is discussed. The theory could explain the experiments, especially concerning the sensitive dependence of HSG signals on the ellipticity of the THz field: the signals are strong when the THz field has a linear polarization and totally vanish in case of a circular polarization. More interestingly, it was found that the strongest signal is not produced in the case of linear polarization for some sidebands. The theory is supported by numerical calculations.

  9. Design and fabrication of 6.1-.ANG. family semiconductor devices using semi-insulating A1Sb substrate

    Energy Technology Data Exchange (ETDEWEB)

    Sherohman, John W [Livermore, CA; Coombs, III, Arthur W. (Patterson, CA); Yee, Jick Hong [Livermore, CA; Wu, Kuang Jen J [Cupertino, CA

    2007-05-29

    For the first time, an aluminum antimonide (AlSb) single crystal substrate is utilized to lattice-match to overlying semiconductor layers. The AlSb substrate establishes a new design and fabrication approach to construct high-speed, low-power electronic devices while establishing inter-device isolation. Such lattice matching between the substrate and overlying semiconductor layers minimizes the formation of defects, such as threaded dislocations, which can decrease the production yield and operational life-time of 6.1-.ANG. family heterostructure devices.

  10. Acousto-optic modulation of III-V semiconductor multiple quantum wells

    International Nuclear Information System (INIS)

    Smith, D.L.; Kogan, S.M.; Ruden, P.P.; Mailhiot, C.

    1996-01-01

    We present an analysis of the effect of surface acoustic waves (SAW close-quote s) on the optical properties of III-V semiconductor multiple quantum wells (MQW close-quote s). Modulation spectra at the fundamental and second harmonic of the SAW frequency are presented. The SAW modulates the optical properties of the MQW primarily by changing optical transition energies. The SAW generates both strains, which modulate the transition energies by deformation potential effects, and electric fields, which modulate the transition energies by the quantum confined Stark effect. We find that modulation of the transition energies by strain effects is usually more important than by electric-field effects. If large static electric fields occur in the MQW, the SAW-generated electric field can mix with the static field to give optical modulation, which is comparable in magnitude to modulation from the deformation potential effect. If there are no large static electric fields, modulation by the SAW-generated fields is negligible. A large static electric field distributes oscillator strength among the various optical transitions so that no single transition is as strong as the primary allowed transitions without a static electric field. To achieve the maximum modulation for fixed SAW parameters, it is best to modulate a strong optical transition. Thus optimum modulation occurs when there are no large static electric fields present and that modulation is primarily from deformation potential effects. We specifically consider Ga x In 1-x As/Ga x Al 1-x As MQW close-quote s grown on (100) and (111) oriented substrates, but our general conclusions apply to other type I MQW close-quote s fabricated from III-V semiconductors. copyright 1996 The American Physical Society

  11. Study of surface modifications for improved selected metal (II-VI) semiconductor based devices

    Science.gov (United States)

    Blomfield, Christopher James

    Metal-semiconductor contacts are of fundamental importance to the operation of all semiconductor devices. There are many competing theories of Schottky barrier formation but as yet no quantitative predictive model exists to adequately explain metal-semiconductor interfaces. The II-VI compound semiconductors CdTe, CdS and ZnSe have recently come to the fore with the advent of high efficiency photovoltaic cells and short wavelength light emitters. Major problems still exist however in forming metal contacts to these materials with the desired properties. This work presents results which make a significant contribution to the theory of metal/II-VI interface behaviour in terms of Schottky barriers to n-type CdTe, CdS and ZnSe.Predominantly aqueous based wet chemical etchants were applied to the surfaces of CdTe, CdS and ZnSe which were subsequently characterised by X-ray photoelectron spectroscopy. The ionic nature of these II-VI compounds meant that they behaved as insoluble salts of strong bases and weak acids. Acid etchants induced a stoichiometric excess of semiconductor anion at the surface which appeared to be predominantly in the elemental or hydrogenated state. Alkaline etchants conversely induced a stoichiometric excess of semiconductor cation at the surface which appeared to be in an oxidised state.Metal contacts were vacuum-evaporated onto these etched surfaces and characterised by current-voltage and capacitance-voltage techniques. The surface preparation was found to have a clear influence upon the electrical properties of Schottky barriers formed to etched surfaces. Reducing the native surface oxide produced near ideal Schottky diodes. An extended study of Au, Ag and Sb contacts to [mathematical formula] substrates again revealed the formation of several discrete Schottky barriers largely independent of the metal used; for [mathematical formula]. Deep levels measured within this study and those reported in the literature led to the conclusion that Fermi

  12. Group III nitride semiconductors for short wavelength light-emitting devices

    Science.gov (United States)

    Orton, J. W.; Foxon, C. T.

    1998-01-01

    The group III nitrides (AlN, GaN and InN) represent an important trio of semiconductors because of their direct band gaps which span the range 1.95-6.2 eV, including the whole of the visible region and extending well out into the ultraviolet (UV) range. They form a complete series of ternary alloys which, in principle, makes available any band gap within this range and the fact that they also generate efficient luminescence has been the main driving force for their recent technological development. High brightness visible light-emitting diodes (LEDs) are now commercially available, a development which has transformed the market for LED-based full colour displays and which has opened the way to many other applications, such as in traffic lights and efficient low voltage, flat panel white light sources. Continuously operating UV laser diodes have also been demonstrated in the laboratory, exciting tremendous interest for high-density optical storage systems, UV lithography and projection displays. In a remarkably short space of time, the nitrides have therefore caught up with and, in some ways, surpassed the wide band gap II-VI compounds (ZnCdSSe) as materials for short wavelength optoelectronic devices. The purpose of this paper is to review these developments and to provide essential background material in the form of the structural, electronic and optical properties of the nitrides, relevant to these applications. We have been guided by the fact that the devices so far available are based on the binary compound GaN (which is relatively well developed at the present time), together with the ternary alloys AlGaN and InGaN, containing modest amounts of Al or In. We therefore concentrate, to a considerable extent, on the properties of GaN, then introduce those of the alloys as appropriate, emphasizing their use in the formation of the heterostructures employed in devices. The nitrides crystallize preferentially in the hexagonal wurtzite structure and devices have so

  13. Charge collection efficiency degradation induced by MeV ions in semiconductor devices: Model and experiment

    Energy Technology Data Exchange (ETDEWEB)

    Vittone, E., E-mail: ettore.vittone@unito.it [Department of Physics, NIS Research Centre and CNISM, University of Torino, via P. Giuria 1, 10125 Torino (Italy); Pastuovic, Z. [Centre for Accelerator Science (ANSTO), Locked bag 2001, Kirrawee DC, NSW 2234 (Australia); Breese, M.B.H. [Centre for Ion Beam Applications (CIBA), Department of Physics, National University of Singapore, Singapore 117542 (Singapore); Garcia Lopez, J. [Centro Nacional de Aceleradores (CNA), Sevilla University, J. Andalucia, CSIC, Av. Thomas A. Edison 7, 41092 Sevilla (Spain); Jaksic, M. [Department for Experimental Physics, Ruder Boškovic Institute (RBI), P.O. Box 180, 10002 Zagreb (Croatia); Raisanen, J. [Department of Physics, University of Helsinki, Helsinki 00014 (Finland); Siegele, R. [Centre for Accelerator Science (ANSTO), Locked bag 2001, Kirrawee DC, NSW 2234 (Australia); Simon, A. [International Atomic Energy Agency (IAEA), Vienna International Centre, P.O. Box 100, 1400 Vienna (Austria); Institute of Nuclear Research of the Hungarian Academy of Sciences (ATOMKI), Debrecen (Hungary); Vizkelethy, G. [Sandia National Laboratories (SNL), PO Box 5800, Albuquerque, NM (United States)

    2016-04-01

    Highlights: • We study the electronic degradation of semiconductors induced by ion irradiation. • The experimental protocol is based on MeV ion microbeam irradiation. • The radiation induced damage is measured by IBIC. • The general model fits the experimental data in the low level damage regime. • Key parameters relevant to the intrinsic radiation hardness are extracted. - Abstract: This paper investigates both theoretically and experimentally the charge collection efficiency (CCE) degradation in silicon diodes induced by energetic ions. Ion Beam Induced Charge (IBIC) measurements carried out on n- and p-type silicon diodes which were previously irradiated with MeV He ions show evidence that the CCE degradation does not only depend on the mass, energy and fluence of the damaging ion, but also depends on the ion probe species and on the polarization state of the device. A general one-dimensional model is derived, which accounts for the ion-induced defect distribution, the ionization profile of the probing ion and the charge induction mechanism. Using the ionizing and non-ionizing energy loss profiles resulting from simulations based on the binary collision approximation and on the electrostatic/transport parameters of the diode under study as input, the model is able to accurately reproduce the experimental CCE degradation curves without introducing any phenomenological additional term or formula. Although limited to low level of damage, the model is quite general, including the displacement damage approach as a special case and can be applied to any semiconductor device. It provides a method to measure the capture coefficients of the radiation induced recombination centres. They can be considered indexes, which can contribute to assessing the relative radiation hardness of semiconductor materials.

  14. Simulation of space protons influence on silicon semiconductor devices using gamma-neutron irradiation

    International Nuclear Information System (INIS)

    Zhukov, Y.N.; Zinchenko, V.F.; Ulimov, V.N.

    1999-01-01

    In this study the authors focus on the problems of simulating the space proton energy spectra under laboratory gamma-neutron radiation tests of semiconductor devices (SD). A correct simulation of radiation effects implies to take into account and evaluate substantial differences in the processes of formation of primary defects in SD in space environment and under laboratory testing. These differences concern: 1) displacement defects, 2) ionization defects and 3) intensity of radiation. The study shows that: - the energy dependence of nonionizing energy loss (NIEL) is quite universal to predict the degradation of SD parameters associated to displacement defects, and - MOS devices that are sensitive to ionization defects indicated the same variation of parameters under conditions of equality of ionization density generated by protons and gamma radiations. (A.C.)

  15. The world's first high voltage GaN-on-Diamond power semiconductor devices

    Science.gov (United States)

    Baltynov, Turar; Unni, Vineet; Narayanan, E. M. Sankara

    2016-11-01

    This paper presents the detailed fabrication method and extensive electrical characterisation results of the first-ever demonstrated high voltage GaN power semiconductor devices on CVD Diamond substrate. Fabricated circular GaN-on-Diamond HEMTs with gate-to-drain drift length of 17 μm and source field plate length of 3 μm show an off-state breakdown voltage of ∼1100 V. Temperature characterisation of capacitance-voltage characteristics and on-state characteristics provides insight on the temperature dependence of key parameters such as threshold voltage, 2DEG sheet carrier concentration, specific on-state resistance, and drain saturation current in the fabricated devices.

  16. Double relaxation oscillation superconducting quantum interference devices with gradiometric layout

    International Nuclear Information System (INIS)

    van Duuren, M.J.; Brons, G.C.; Adelerhof, D.J.; Flokstra, J.; Rogalla, H.

    1997-01-01

    Double relaxation oscillation superconducting quantum interference devices (DROSs) with a gradiometric signal SQUID and either a reference SQUID or a reference junction will be presented in this article. The devices are user friendly, particularly those with a reference junction. Because of the large flux-to-voltage transfer of ∂V/∂Φ=0.7 endash 1mV/Φ 0 , the devices can be operated in a flux locked loop based on direct voltage readout without loss of sensitivity. The typical white flux noise of the DROSs amounts to √S Φ =5 endash 6μΦ 0 /√Hz, which corresponds to an energy resolution ε=S Φ /2L sq ≅200h. Coupled to an external planar first-order gradiometer, a white magnetic field sensitivity of √S B <2fT/√Hz was measured inside a magnetically shielded room. copyright 1997 American Institute of Physics

  17. Prospects of IMPATT devices based on wide bandgap semiconductors as potential terahertz sources

    Science.gov (United States)

    Acharyya, Aritra; Banerjee, J. P.

    2014-01-01

    In this paper the potentiality of impact avalanche transit time (IMPATT) devices based on different semiconductor materials such as GaAs, Si, InP, 4H-SiC and Wurtzite-GaN (Wz-GaN) has been explored for operation at terahertz frequencies. Drift-diffusion model is used to design double-drift region (DDR) IMPATTs based on different materials at millimeter-wave (mm-wave) and terahertz (THz) frequencies. The performance limitations of these devices are studied from the avalanche response times at different mm-wave and THz frequencies. Results show that the upper cut-off frequency limits of GaAs and Si DDR IMPATTs are 220 GHz and 0.5 THz, respectively, whereas the same for InP and 4H-SiC DDR IMPATTs is 1.0 THz. Wz-GaN DDR IMPATTs are found to be excellent candidate for generation of RF power at THz frequencies of the order of 5.0 THz with appreciable DC to RF conversion efficiency. Further, it is observed that up to 1.0 THz, 4H-SiC DDR IMPATTs excel Wz-GaN DDR IMPATTs as regards their RF power outputs. Thus, the wide bandgap semiconductors such as Wz-GaN and 4H-SiC are highly suitable materials for DDR IMPATTs at both mm-wave and THz frequency ranges.

  18. 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

  19. (Nanotechnology Initiative) Revision of Quantum Engineering of Nanostructures for Optoelectronic Devices with Optimum Performance

    Science.gov (United States)

    2011-10-11

    based on Quantum Dots and Resonant- Tunneling Diodes Coupled with Conductive Polymers Growth and Properties of Tin Oxide Nanowires and the Effect...Physical Limit for Nanoscale Optoelectronic Device Three-color Photodetector based on Quantum Dots and Resonant- tunneling Diodes coupled with...Bottleneck Effects in Rectangular Graphene Quantum Dots Interface Optical Phonon Modes in Wurtzite Quantum Heterostructures Multi-Color Photodetector

  20. A cost-effective measurement-device-independent quantum key distribution system for quantum networks

    Science.gov (United States)

    Valivarthi, Raju; Zhou, Qiang; John, Caleb; Marsili, Francesco; Verma, Varun B.; Shaw, Matthew D.; Nam, Sae Woo; Oblak, Daniel; Tittel, Wolfgang

    2017-12-01

    We experimentally realize a measurement-device-independent quantum key distribution (MDI-QKD) system. It is based on cost-effective and commercially available hardware such as distributed feedback lasers and field-programmable gate arrays that enable time-bin qubit preparation and time-tagging, and active feedback systems that allow for compensation of time-varying properties of photons after transmission through deployed fiber. We examine the performance of our system, and conclude that its design does not compromise performance. Our demonstration paves the way for MDI-QKD-based quantum networks in star-type topology that extend over more than 100 km distance.

  1. Binding of two-electron metastable states in semiconductor quantum dots under a magnetic field

    Science.gov (United States)

    Garagiola, Mariano; Pont, Federico M.; Osenda, Omar

    2018-04-01

    Applying a strong enough magnetic field results in the binding of few-electron resonant states. The mechanism was proposed many years ago but its verification in laboratory conditions is far more recent. In this work we study the binding of two-electron resonant states. The electrons are confined in a cylindrical quantum dot which is embedded in a semiconductor wire. The geometry considered is similar to the one used in actual experimental setups. The low-energy two-electron spectrum is calculated numerically from an effective-mass approximation Hamiltonian modelling the system. Methods for binding threshold calculations in systems with one and two electrons are thoroughly studied; in particular, we use quantum information quantities to assess when the strong lateral confinement approximation can be used to obtain reliable low-energy spectra. For simplicity, only cases without bound states in the absence of an external field are considered. Under these conditions, the binding threshold for the one-electron case is given by the lowest Landau energy level. Moreover, the energy of the one-electron bounded resonance can be used to obtain the two-electron binding threshold. It is shown that for realistic values of the two-electron model parameters it is feasible to bind resonances with field strengths of a few tens of tesla.

  2. Silver Nanoshell Plasmonically Controlled Emission of Semiconductor Quantum Dots in the Strong Coupling Regime.

    Science.gov (United States)

    Zhou, Ning; Yuan, Meng; Gao, Yuhan; Li, Dongsheng; Yang, Deren

    2016-04-26

    Strong coupling between semiconductor excitons and localized surface plasmons (LSPs) giving rise to hybridized plexciton states in which energy is coherently and reversibly exchanged between the components is vital, especially in the area of quantum information processing from fundamental and practical points of view. Here, in photoluminescence spectra, rather than from common extinction or reflection measurements, we report on the direct observation of Rabi splitting of approximately 160 meV as an indication of strong coupling between excited states of CdSe/ZnS quantum dots (QDs) and LSP modes of silver nanoshells under nonresonant nanosecond pulsed laser excitation at room temperature. The strong coupling manifests itself as an anticrossing-like behavior of the two newly formed polaritons when tuning the silver nanoshell plasmon energies across the exciton line of the QDs. Further analysis substantiates the essentiality of high pump energy and collective strong coupling of many QDs with the radiative dipole mode of the metallic nanoparticles for the realization of strong coupling. Our finding opens up interesting directions for the investigation of strong coupling between LSPs and excitons from the perspective of radiative recombination under easily accessible experimental conditions.

  3. Memory-assisted measurement-device-independent quantum key distribution

    International Nuclear Information System (INIS)

    Panayi, Christiana; Razavi, Mohsen; Ma, Xiongfeng; Lütkenhaus, Norbert

    2014-01-01

    A protocol with the potential of beating the existing distance records for conventional quantum key distribution (QKD) systems is proposed. It borrows ideas from quantum repeaters by using memories in the middle of the link, and that of measurement-device-independent QKD, which only requires optical source equipment at the user's end. For certain memories with short access times, our scheme allows a higher repetition rate than that of quantum repeaters with single-mode memories, thereby requiring lower coherence times. By accounting for various sources of nonideality, such as memory decoherence, dark counts, misalignment errors, and background noise, as well as timing issues with memories, we develop a mathematical framework within which we can compare QKD systems with and without memories. In particular, we show that with the state-of-the-art technology for quantum memories, it is potentially possible to devise memory-assisted QKD systems that, at certain distances of practical interest, outperform current QKD implementations. (paper)

  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. 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.

  6. Fast pixelated sensors for radiation detection and imaging based on quantum confined structures in III/V semiconductors

    International Nuclear Information System (INIS)

    Tortora, M.; Biasiol, G.; Cautero, G.; Menk, R.H.; Plaisier, J.R.; Antonelli, M.

    2017-01-01

    In order to improve the characterisation of the delivered beams in many types of photon sources, innovative beam profilers based on III/V semiconductor materials (InGaAs/InAlAs) have been deeply investigated. Owing to a tunable and direct band gap these devices allow radiation detection in a wide spectral range. In order to increase the sensitivity of the device in radiation detection charge amplification on the sensor level is implemented. This is obtained by exploiting In 0.75 Ga 0.25 As/In 0.75 Al 0.25 As quantum wells (QW) hosting a two-dimensional electron gas (2DEG) through molecular beam epitaxy (MBE). Internal charge-amplification mechanism can be achieved for very low applied voltages, while the high carrier mobility allows the design of very fast photon detectors with sub-nanosecond response times. This technology has been preliminarily exploited to fabricate prototype beam profilers with a strip geometry (with 50-μm-wide strips). Tests were carried out both with conventional X-ray tubes and at the Elettra synchrotron facility. The results testify how these profilers are capable of reconstructing the shape of the beam, as well as estimating the position of the beam centroid with a precision of about 400 nm. Further measurements with different samples of decreasing thickness have shown how this precision could be further improved by an optimised microfabrication. For this reason a new design, based on a membrane-photodetector, is proposed. Results regarding the spatial resolution as function of the sensor thickness will be presented and discussed.

  7. Quantifying the cellular uptake of semiconductor quantum dot nanoparticles by analytical electron microscopy.

    Science.gov (United States)

    Hondow, Nicole; Brown, M Rowan; Starborg, Tobias; Monteith, Alexander G; Brydson, Rik; Summers, Huw D; Rees, Paul; Brown, Andy

    2016-02-01

    Semiconductor quantum dot nanoparticles are in demand as optical biomarkers yet the cellular uptake process is not fully understood; quantification of numbers and the fate of internalized particles are still to be achieved. We have focussed on the characterization of cellular uptake of quantum dots using a combination of analytical electron microscopies because of the spatial resolution available to examine uptake at the nanoparticle level, using both imaging to locate particles and spectroscopy to confirm identity. In this study, commercially available quantum dots, CdSe/ZnS core/shell particles coated in peptides to target cellular uptake by endocytosis, have been investigated in terms of the agglomeration state in typical cell culture media, the traverse of particle agglomerates across U-2 OS cell membranes during endocytosis, the merging of endosomal vesicles during incubation of cells and in the correlation of imaging flow cytometry and transmission electron microscopy to measure the final nanoparticle dose internalized by the U-2 OS cells. We show that a combination of analytical transmission electron microscopy and serial block face scanning electron microscopy can provide a comprehensive description of the internalization of an initial exposure dose of nanoparticles by an endocytically active cell population and how the internalized, membrane bound nanoparticle load is processed by the cells. We present a stochastic model of an endosome merging process and show that this provides a data-driven modelling framework for the prediction of cellular uptake of engineered nanoparticles in general. © 2015 The Authors Journal of Microscopy © 2015 Royal Microscopical Society.

  8. The importance of Fe interface states for ferromagnet-semiconductor based spintronic devices

    Science.gov (United States)

    Chantis, Athanasios

    2009-03-01

    I present our recent theoretical studies of the bias-controlled spin injection, detection sensitivity and tunneling anisotropic magnetoresistance in ferromagnetic-semiconductor tunnel junctions. Using first-principles electron transport methods we have shown that Fe 3d minority-spin surface (interface) states are responsible for at least two important effects for spin electronics. First, they can produce a sizable Tunneling Anisotropic Magnetoresistance in magnetic tunnel junctions with a single Fe electrode. The effect is driven by a Rashba shift of the resonant surface band when the magnetization changes direction. This can introduce a new class of spintronic devices, namely, Tunneling Magnetoresistance junctions with a single ferromagnetic electrode that can function at room temperatures. Second, in Fe/GaAs(001) magnetic tunnel junctions they produce a strong dependence of the tunneling current spin-polarization on applied electrical bias. A dramatic sign reversal within a voltage range of just a few tenths of an eV is found. This explains the observed sign reversal of spin-polarization in recent experiments of electrical spin injection in Fe/GaAs(001) and related reversal of tunneling magnetoresistcance through vertical Fe/GaAs/Fe trilayers. We also present a theoretical description of electrical spin-detection at a ferromagnet/semiconductor interface. We show that the sensitivity of the spin detector has strong bias dependence which, in the general case, is dramatically different from that of the tunneling current spin-polarization. We show that in realistic ferromagnet/semiconductor junctions this bias dependence can originate from two distinct physical mechanisms: 1) the bias dependence of tunneling current spin-polarization, which is of microscopic origin and depends on the specific properties of the interface, and 2) the macroscopic electron spin transport properties in the semiconductor. Our numerical results show that the magnitude of the voltage signal

  9. Implementation of quantum partial search with superconducting quantum interference device qudits in cavity QED

    International Nuclear Information System (INIS)

    Li Hong-Yi; Wu Chun-Wang; Chen Yu-Bo; Lin Yuan-Gen; Chen Ping-Xing; Li Cheng-Zu

    2013-01-01

    We present a method to implement the quantum partial search of the database separated into any number of blocks with qudits, D-level quantum systems. Compared with the partial search using qubits, our method needs fewer iteration steps and uses the carriers of the information more economically. To illustrate how to realize the idea with concrete physical systems, we propose a scheme to carry out a twelve-dimensional partial search of the database partitioned into three blocks with superconducting quantum interference devices (SQUIDs) in cavity QED. Through the appropriate modulation of the amplitudes of the microwave pulses, the scheme can overcome the non-identity of the cavity—SQUID coupling strengths due to the parameter variations resulting from the fabrication processes. Numerical simulation under the influence of the cavity and SQUID decays shows that the scheme could be achieved efficiently within current state-of-the-art technology

  10. Development of Room Temperature Excitonic Lasing From ZnO and MgZnO Thin Film Based Metal-Semiconductor-Metal Devices

    Science.gov (United States)

    Suja, Mohammad Zahir Uddin

    Room temperature excitonic lasing is demonstrated and developed by utilizing metal-semiconductor-metal devices based on ZnO and MgZnO materials. At first, Cu-doped p-type ZnO films are grown on c-sapphire substrates by plasma-assisted molecular beam epitaxy. Photoluminescence (PL) experiments reveal a shallow acceptor state at 0.15 eV above the valence band edge. Hall effect results indicate that a growth condition window is found for the formation of p-type ZnO thin films and the best conductivity is achieved with a high hole concentration of 1.54x1018 cm-3, a low resistivity of 0.6 O cm and a moderate mobility of 6.65 cm2 V -1 s-1 at room temperature. Metal oxide semiconductor (MOS) capacitor devices have been fabricated on the Cu-doped ZnO films and the characteristics of capacitance-voltage measurements demonstrate that the Cu-doped ZnO thin films under proper growth conditions are p-type. Seebeck measurements on these Cu-doped ZnO samples lead to positive Seebeck coefficients and further confirm the p-type conductivity. Other measurements such as XRD, XPS, Raman and absorption are also performed to elucidate the structural and optical characteristics of the Cu-doped p-type ZnO films. The p-type conductivity is explained to originate from Cu substitution of Zn with a valency of +1 state. However, all p-type samples are converted to n-type over time, which is mostly due to the carrier compensation from extrinsic defects of ZnO. To overcome the stability issue of p-type ZnO film, alternate devices other than p-n junction has been developed. Electrically driven plasmon-exciton coupled random lasing is demonstrated by incorporating Ag nanoparticles on Cu-doped ZnO metal-semiconductor-metal (MSM) devices. Both photoluminescence and electroluminescence studies show that emission efficiencies have been enhanced significantly due to coupling between ZnO excitons and Ag surface plasmons. With the incorporation of Ag nanoparticles on ZnO MSM structures, internal quantum

  11. Self-assembling hybrid diamond-biological quantum devices

    Science.gov (United States)

    Albrecht, A.; Koplovitz, G.; Retzker, A.; Jelezko, F.; Yochelis, S.; Porath, D.; Nevo, Y.; Shoseyov, O.; Paltiel, Y.; Plenio, M. B.

    2014-09-01

    The realization of scalable arrangements of nitrogen vacancy (NV) centers in diamond remains a key challenge on the way towards efficient quantum information processing, quantum simulation and quantum sensing applications. Although technologies based on implanting NV-centers in bulk diamond crystals or hybrid device approaches have been developed, they are limited by the achievable spatial resolution and by the intricate technological complexities involved in achieving scalability. We propose and demonstrate a novel approach for creating an arrangement of NV-centers, based on the self-assembling capabilities of biological systems and their beneficial nanometer spatial resolution. Here, a self-assembled protein structure serves as a structural scaffold for surface functionalized nanodiamonds, in this way allowing for the controlled creation of NV-structures on the nanoscale and providing a new avenue towards bridging the bio-nano interface. One-, two- as well as three-dimensional structures are within the scope of biological structural assembling techniques. We realized experimentally the formation of regular structures by interconnecting nanodiamonds using biological protein scaffolds. Based on the achievable NV-center distances of 11 nm, we evaluate the expected dipolar coupling interaction with neighboring NV-centers as well as the expected decoherence time. Moreover, by exploiting these couplings, we provide a detailed theoretical analysis on the viability of multiqubit quantum operations, suggest the possibility of individual addressing based on the random distribution of the NV intrinsic symmetry axes and address the challenges posed by decoherence and imperfect couplings. We then demonstrate in the last part that our scheme allows for the high-fidelity creation of entanglement, cluster states and quantum simulation applications.

  12. Self-assembled InAs/InP quantum dots and quantum dashes: Material structures and devices

    KAUST Repository

    Khan, Mohammed Zahed Mustafa

    2014-11-01

    The advances in lasers, electronic and photonic integrated circuits (EPIC), optical interconnects as well as the modulation techniques allow the present day society to embrace the convenience of broadband, high speed internet and mobile network connectivity. However, the steep increase in energy demand and bandwidth requirement calls for further innovation in ultra-compact EPIC technologies. In the optical domain, advancement in the laser technologies beyond the current quantum well (Qwell) based laser technologies are already taking place and presenting very promising results. Homogeneously grown quantum dot (Qdot) lasers and optical amplifiers, can serve in the future energy saving information and communication technologies (ICT) as the work-horse for transmitting and amplifying information through optical fiber. The encouraging results in the zero-dimensional (0D) structures emitting at 980 nm, in the form of vertical cavity surface emitting laser (VCSEL), are already operational at low threshold current density and capable of 40 Gbps error-free transmission at 108 fJ/bit. Subsequent achievements for lasers and amplifiers operating in the O-, C-, L-, U-bands, and beyond will eventually lay the foundation for green ICT. On the hand, the inhomogeneously grown quasi 0D quantum dash (Qdash) lasers are brilliant solutions for potential broadband connectivity in server farms or access network. A single broadband Qdash laser operating in the stimulated emission mode can replace tens of discrete narrow-band lasers in dense wavelength division multiplexing (DWDM) transmission thereby further saving energy, cost and footprint. We herein reviewed the1 progress of both Qdots and Qdash devices, based on the InAs/InGaAlAs/InP and InAs/InGaAsP/InP material systems, from the angles of growth and device performance. In particular, we discussed the progress in lasers, semiconductor optical amplifiers (SOA), mode locked lasers, and superluminescent diodes, which are the building

  13. Organic-inorganic semiconductor devices and 3, 4, 9, 10 perylenetetracarboxylic dianhydride: an early history of organic electronics

    International Nuclear Information System (INIS)

    Forrest, S R

    2003-01-01

    The demonstration, over 20 years ago, of an organic-inorganic heterojunction (OI HJ) device along with investigations of the growth and physical properties of the archetypal crystalline molecular organic semiconductor 3, 4, 9, 10 perylenetetracarboxylic dianhydride are discussed. Possible applications of OI HJ devices are introduced and the dramatic change in conductive properties of these materials when exposed to high-energy ion beams is described. The past and future prospects for hybrid organic-on-inorganic semiconductor structures for use in electronic and photonic applications are also presented

  14. Device independent quantum key distribution secure against coherent attacks with memoryless measurement devices

    International Nuclear Information System (INIS)

    McKague, Matthew

    2009-01-01

    Device independent quantum key distribution (QKD) aims to provide a higher degree of security than traditional QKD schemes by reducing the number of assumptions that need to be made about the physical devices used. The previous proof of security by Pironio et al (2009 New J. Phys. 11 045021) applies only to collective attacks where the state is identical and independent and the measurement devices operate identically for each trial in the protocol. We extend this result to a more general class of attacks where the state is arbitrary and the measurement devices have no memory. We accomplish this by a reduction of arbitrary adversary strategies to qubit strategies and a proof of security for qubit strategies based on the previous proof by Pironio et al and techniques adapted from Renner.

  15. Single-electron-occupation metal-oxide-semiconductor quantum dots formed from efficient poly-silicon gate layout

    Energy Technology Data Exchange (ETDEWEB)

    Carroll, Malcolm S.; rochette, sophie; Rudolph, Martin; Roy, A. -M.; Curry, Matthew Jon; Ten Eyck, Gregory A.; Manginell, Ronald P.; Wendt, Joel R.; Pluym, Tammy; Carr, Stephen M; Ward, Daniel Robert; Lilly, Michael; pioro-ladriere, michel

    2017-07-01

    We introduce a silicon metal-oxide-semiconductor quantum dot structure that achieves dot-reservoir tunnel coupling control without a dedicated barrier gate. The elementary structure consists of two accumulation gates separated spatially by a gap, one gate accumulating a reservoir and the other a quantum dot. Control of the tunnel rate between the dot and the reservoir across the gap is demonstrated in the single electron regime by varying the reservoir accumulation gate voltage while compensating with the dot accumulation gate voltage. The method is then applied to a quantum dot connected in series to source and drain reservoirs, enabling transport down to the single electron regime. Finally, tuning of the valley splitting with the dot accumulation gate voltage is observed. This split accumulation gate structure creates silicon quantum dots of similar characteristics to other realizations but with less electrodes, in a single gate stack subtractive fabrication process that is fully compatible with silicon foundry manufacturing.

  16. Photoinduced electron transfer from semiconductor quantum dots to metal oxide nanoparticles.

    Science.gov (United States)

    Tvrdy, Kevin; Frantsuzov, Pavel A; Kamat, Prashant V

    2011-01-04

    Quantum dot-metal oxide junctions are an integral part of next-generation solar cells, light emitting diodes, and nanostructured electronic arrays. Here we present a comprehensive examination of electron transfer at these junctions, using a series of CdSe quantum dot donors (sizes 2.8, 3.3, 4.0, and 4.2 nm in diameter) and metal oxide nanoparticle acceptors (SnO(2), TiO(2), and ZnO). Apparent electron transfer rate constants showed strong dependence on change in system free energy, exhibiting a sharp rise at small driving forces followed by a modest rise further away from the characteristic reorganization energy. The observed trend mimics the predicted behavior of electron transfer from a single quantum state to a continuum of electron accepting states, such as those present in the conduction band of a metal oxide nanoparticle. In contrast with dye-sensitized metal oxide electron transfer studies, our systems did not exhibit unthermalized hot-electron injection due to relatively large ratios of electron cooling rate to electron transfer rate. To investigate the implications of these findings in photovoltaic cells, quantum dot-metal oxide working electrodes were constructed in an identical fashion to the films used for the electron transfer portion of the study. Interestingly, the films which exhibited the fastest electron transfer rates (SnO(2)) were not the same as those which showed the highest photocurrent (TiO(2)). These findings suggest that, in addition to electron transfer at the quantum dot-metal oxide interface, other electron transfer reactions play key roles in the determination of overall device efficiency.

  17. An enzymatically-sensitized sequential and concentric energy transfer relay self-assembled around semiconductor quantum dots.

    Science.gov (United States)

    Samanta, Anirban; Walper, Scott A; Susumu, Kimihiro; Dwyer, Chris L; Medintz, Igor L

    2015-05-07

    The ability to control light energy within de novo nanoscale structures and devices will greatly benefit their continuing development and ultimate application. Ideally, this control should extend from generating the light itself to its spatial propagation within the device along with providing defined emission wavelength(s), all in a stand-alone modality. Here we design and characterize macromolecular nanoassemblies consisting of semiconductor quantum dots (QDs), several differentially dye-labeled peptides and the enzyme luciferase which cumulatively demonstrate many of these capabilities by engaging in multiple-sequential energy transfer steps. To create these structures, recombinantly-expressed luciferase and the dye-labeled peptides were appended with a terminal polyhistidine sequence allowing for controlled ratiometric self-assembly around the QDs via metal-affinity coordination. The QDs serve to provide multiple roles in these structures including as central assembly platforms or nanoscaffolds along with acting as a potent energy harvesting and transfer relay. The devices are activated by addition of coelenterazine H substrate which is oxidized by luciferase producing light energy which sensitizes the central 625 nm emitting QD acceptor by bioluminescence resonance energy transfer (BRET). The sensitized QD, in turn, acts as a relay and transfers the energy to a first peptide-labeled Alexa Fluor 647 acceptor dye displayed on its surface. This dye then transfers energy to a second red-shifted peptide-labeled dye acceptor on the QD surface through a second concentric Förster resonance energy transfer (FRET) process. Alexa Fluor 700 and Cy5.5 are both tested in the role of this terminal FRET acceptor. Photophysical analysis of spectral profiles from the resulting sequential BRET-FRET-FRET processes allow us to estimate the efficiency of each of the transfer steps. Importantly, the efficiency of each step within this energy transfer cascade can be controlled to

  18. On high-speed cross-gain modulation without pattern effects in quantum dot semiconductor optical amplifiers

    DEFF Research Database (Denmark)

    Uskov, A.V.; Mørk, Jesper; Tromborg, Bjarne

    2003-01-01

    In the regime with maximum linear gain in a quantum dot (QD) semiconductor optical amplifier (SOA), instantaneous gain modulation by change of the photon density is possible due to spectral hole burning effects. This, in turn, leads to the opportunity of ultrafast cross-gain modulation (XGM) with......) without pattern effects at modulation bit-rates much higher than the interband relaxation rate. The maximum bit-rate for this pattern-effect-free XGM grows with increasing pump current density of the QD SOA.......In the regime with maximum linear gain in a quantum dot (QD) semiconductor optical amplifier (SOA), instantaneous gain modulation by change of the photon density is possible due to spectral hole burning effects. This, in turn, leads to the opportunity of ultrafast cross-gain modulation (XGM...

  19. An empirical formula for yield estimation from singly truncated performance data of qualified semiconductor devices

    International Nuclear Information System (INIS)

    Liang Tao; Jia Xinzhang

    2012-01-01

    The problem of yield estimation merely from performance test data of qualified semiconductor devices is studied. An empirical formula is presented to calculate the yield directly by the sample mean and standard deviation of singly truncated normal samples based on the theoretical relation between process capability indices and the yield. Firstly, we compare four commonly used normality tests under different conditions, and simulation results show that the Shapiro—Wilk test is the most powerful test in recognizing singly truncated normal samples. Secondly, the maximum likelihood estimation method and the empirical formula are compared by Monte Carlo simulation. The results show that the simple empirical formulas can achieve almost the same accuracy as the maximum likelihood estimation method but with a much lower amount of calculations when estimating yield from singly truncated normal samples. In addition, the empirical formula can also be used for doubly truncated normal samples when some specific conditions are met. Practical examples of yield estimation from academic and IC test data are given to verify the effectiveness of the proposed method. (semiconductor integrated circuits)

  20. Heterodyne mixing of millimetre electromagnetic waves and sub-THz sound in a semiconductor device.

    Science.gov (United States)

    Heywood, Sarah L; Glavin, Boris A; Beardsley, Ryan P; Akimov, Andrey V; Carr, Michael W; Norman, James; Norton, Philip C; Prime, Brian; Priestley, Nigel; Kent, Anthony J

    2016-08-01

    We demonstrate heterodyne mixing of a 94 GHz millimetre wave photonic signal, supplied by a Gunn diode oscillator, with coherent acoustic waves of frequency ~100 GHz, generated by pulsed laser excitation of a semiconductor surface. The mixing takes place in a millimetre wave Schottky diode, and the intermediate frequency electrical signal is in the 1-12 GHz range. The mixing process preserves all the spectral content in the acoustic signal that falls within the intermediate frequency bandwidth. Therefore this technique may find application in high-frequency acoustic spectroscopy measurements, exploiting the nanometre wavelength of sub-THz sound. The result also points the way to exploiting acoustoelectric effects in photonic devices working at sub-THz and THz frequencies, which could provide functionalities at these frequencies, e.g. acoustic wave filtering, that are currently in widespread use at lower (GHz) frequencies.

  1. Low Temperature Processed Complementary Metal Oxide Semiconductor (CMOS) Device by Oxidation Effect from Capping Layer

    KAUST Repository

    Wang, Zhenwei

    2015-04-20

    In this report, both p- and n-type tin oxide thin-film transistors (TFTs) were simultaneously achieved using single-step deposition of the tin oxide channel layer. The tuning of charge carrier polarity in the tin oxide channel is achieved by selectively depositing a copper oxide capping layer on top of tin oxide, which serves as an oxygen source, providing additional oxygen to form an n-type tin dioxide phase. The oxidation process can be realized by annealing at temperature as low as 190°C in air, which is significantly lower than the temperature generally required to form tin dioxide. Based on this approach, CMOS inverters based entirely on tin oxide TFTs were fabricated. Our method provides a solution to lower the process temperature for tin dioxide phase, which facilitates the application of this transparent oxide semiconductor in emerging electronic devices field.

  2. Semiconductor device simulation by a new method of solving poisson, Laplace and Schrodinger equations

    International Nuclear Information System (INIS)

    Sharifi, M. J.; Adibi, A.

    2000-01-01

    In this paper, we have extended and completed our previous work, that was introducing a new method for finite differentiation. We show the applicability of the method for solving a wide variety of equations such as poisson, Laplace and Schrodinger. These equations are fundamental to the most semiconductor device simulators. In a section, we solve the Shordinger equation by this method in several cases including the problem of finding electron concentration profile in the channel of a HEMT. In another section, we solve the Poisson equation by this method, choosing the problem of SBD as an example. Finally we solve the Laplace equation in two dimensions and as an example, we focus on the VED. In this paper, we have shown that, the method can get stable and precise results in solving all of these problems. Also the programs which have been written based on this method become considerably faster, more clear, and more abstract

  3. Total-dose radiation effects data for semiconductor devices. 1985 supplement. Volume 2, part A

    International Nuclear Information System (INIS)

    Martin, K.E.; Gauthier, M.K.; Coss, J.R.; Dantas, A.R.V.; Price, W.E.

    1986-05-01

    Steady-state, total-dose radiation test data, are provided in graphic format for use by electronic designers and other personnel using semiconductor devices in a radiation environment. The data were generated by JPL for various NASA space programs. This volume provides data on integrated circuits. The data are presented in graphic, tabular, and/or narrative format, depending on the complexity of the integrated circuit. Most tests were done using the JPL or Boeing electron accelerator (Dynamitron) which provides a steady-state 2.5 MeV electron beam. However, some radiation exposures were made with a cobalt-60 gamma ray source, the results of which should be regarded as only an approximate measure of the radiation damage that would be incurred by an equivalent electron dose

  4. Semiconductor devices as track detectors in high energy colliding beam experiments

    Energy Technology Data Exchange (ETDEWEB)

    Ludlam, T

    1980-01-01

    In considering the design of experiments for high energy colliding beam facilities one quickly sees the need for better detectors. The full exploitation of machines like ISABELLE will call for detector capabilities beyond what can be expected from refinements of the conventional approaches to particle detection in high energy physics experiments. Over the past year or so there has been a general realization that semiconductor device technology offers the possibility of position sensing detectors having resolution elements with dimensions of the order of 10 microns or smaller. Such a detector could offer enormous advantages in the design of experiments, and the purpose of this paper is to discuss some of the possibilities and some of the problems.

  5. Semiconductor devices as track detectors in high energy colliding beam experiments

    International Nuclear Information System (INIS)

    Ludlam, T.

    1980-01-01

    In considering the design of experiments for high energy colliding beam facilities one quickly sees the need for better detectors. The full exploitation of machines like ISABELLE will call for detector capabilities beyond what can be expected from refinements of the conventional approaches to particle detection in high energy physics experiments. Over the past year or so there has been a general realization that semiconductor device technology offers the possibility of position sensing detectors having resolution elements with dimensions of the order of 10 microns or smaller. Such a detector could offer enormous advantages in the design of experiments, and the purpose of this paper is to discuss some of the possibilities and some of the problems

  6. Comparison of the Optical Properties of Graphene and Alkyl-terminated Si and Ge Quantum Dots

    NARCIS (Netherlands)

    de Weerd, C.; Shin, Y.; Marino, E.; Kim, J.; Lee, H.; Saeed, S.; Gregorkiewicz, T.

    2017-01-01

    Semiconductor quantum dots are widely investigated due to their size dependent energy structure. In particular, colloidal quantum dots represent a promising nanomaterial for optoelectronic devices, such as photodetectors and solar cells, but also luminescent markers for biotechnology, among other

  7. Bioengineered II-VI semiconductor quantum dot-carboxymethylcellulose nanoconjugates as multifunctional fluorescent nanoprobes for bioimaging live cells

    Science.gov (United States)

    Mansur, Alexandra A. P.; Mansur, Herman S.; Mansur, Rafael L.; de Carvalho, Fernanda G.; Carvalho, Sandhra M.

    2018-01-01

    Colloidal semiconductor quantum dots (QDs) are light-emitting ultra-small nanoparticles, which have emerged as a new class of nanoprobes with unique optical properties for bioimaging and biomedical diagnostic. However, to be used for most biomedical applications the biocompatibility and water-solubility are mandatory that can achieved through surface modification forming QD-nanoconjugates. In this study, semiconductor II-VI quantum dots of type MX (M = Cd, Pb, Zn, X = S) were directly synthesized in aqueous media and at room temperature using carboxymethylcellulose sodium salt (CMC) behaving simultaneously as stabilizing and surface biofunctional ligand. These nanoconjugates were extensively characterized using UV-visible spectroscopy, photoluminescence spectroscopy, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, X-ray diffraction, transmission electron microscopy, dynamic light scattering and zeta potential. The results demonstrated that the biopolymer was effective on nucleating and stabilizing the colloidal nanocrystals of CdS, ZnS, and PbS with the average diameter ranging from 2.0 to 5.0 nm depending on the composition of the semiconductor core, which showed quantum-size confinement effect. These QD/polysaccharide conjugates showed luminescent activity from UV-visible to near-infrared range of the spectra under violet laser excitation. Moreover, the bioassays performed proved that these novel nanoconjugates were biocompatible and behaved as composition-dependent fluorescent nanoprobes for in vitro live cell bioimaging with very promising perspectives to be used in numerous biomedical applications and nanomedicine.

  8. The Physics and Operation of Ultra-Submicron Length Semiconductor Devices.

    Science.gov (United States)

    1994-05-01

    r d CUBo ddmq.b de I,~ tha th dceseAe so the same ,7* -lhml na.i lmg, qpy o-to Cmt a deo-sui= QWI g, 1S O . the oawud ID electron ps coolHng rue bma...the complexity of the RTD and the puzzle associated with understanding its detailed operational principles has led Ferry’ to describe it as the fruit...OUtilization of Quantum Distribution Functions for Uitra-Submicron Device Transport, J. De Physique, 10, C7-307 (1981). 𔃿M. A. Stroscio: ’Moment-Equafion

  9. Optical properties of diluted magnetic semiconductor Cu:ZnS quantum dots

    Science.gov (United States)

    Imam, N. G.; Bakr Mohamed, Mohamed

    2014-09-01

    Herein quantum dots (QDs) of diluted magnetic semiconductor Cu:ZnS have been synthesized via a simple chemical synthesis method. A single phase solid solution is formed up to x = 0.1 which confirmed by using X-ray diffraction. Crystal structure and microstructure analyses were performed by Rietveld refinement. Photoluminescence (PL) emission spectra were recorded for pure and Cu doped ZnS QDs excited at 268 and 228 nm respectively. PL emission and excitation spectra were investigated in different wavelength regions within the range of 200-900 nm. PL results in the range of 220-300 nm emission band reveals that the band gap of pure ZnS QDs is about 4.43 eV which greater than that of bulk ZnS (3.7 eV). The band gap of Cu:ZnS QDs is tunable with Cu content (x) as well as the crystalline size, and it is peaked around 4.47 eV. PL emission in the range of 350-650 nm exhibits a green fluorescence band peaking around 552 nm for pure ZnS QDs, which confirms the characteristic feature of Zn2+ as luminescent centers in the lattice, while blue emission bands peaked around 471 nm for Cu:ZnS QDs that is attributed to the transition of electrons from conduction band of ZnS to the Cu impurity level. The blue shift of the absorption peak directly reflects the effect of quantum confinement. The PL results have been supported by X-ray phase analysis, high-resolution electron microscopy (HRTEM and SEM), compositional evaluation (EDX) and magnetic measurements (VSM).

  10. Review on the degradation and device physics of quantum dot solar cells

    Science.gov (United States)

    Afshar, Elham N.; Rouhi, Rasoul; Gorji, Nima E.

    2015-12-01

    Briefly, we reviewed the latest progress in energy conversion efficiency and degradation rate of the quantum dot (QD) solar cells. QDs are zero dimension nanoparticles with tunable size and accordingly tunable band gap. The maximum performance of the most advanced QD solar cells was reported to be around 10%. Nevertheless, majority of research groups do not investigate the stability of such devices. QDs are cheaper replacements for silicon or other thin film materials with a great potential to significantly increase the photon conversion efficiency via two ways: (i) creating multiple excitons by absorbing a single hot photon, and (ii) formation of intermediate bands (IBs) in the band gap of the background semiconductor that enables the absorption of low energy photons (two-step absorption of sub-band gap photons). Apart from low conversion efficiency, QD solar cells also suffer from instability under real operation and stress conditions. Strain, dislocations and variation in size of the dots (under pressure of the other layers) are the main degradation resources. While some new materials (i.e. perovskites) showed an acceptable high performance, the QD devices are still inefficient with an almost medium rate of 4% (2010) to 10% (2015).

  11. Transmission line pulse system for avalanche characterization of high power semiconductor devices

    Science.gov (United States)

    Riccio, Michele; Ascione, Giovanni; De Falco, Giuseppe; Maresca, Luca; De Laurentis, Martina; Irace, Andrea; Breglio, Giovanni

    2013-05-01

    Because of the increasing in power density of electronic devices for medium and high power application, reliabilty of these devices is of great interest. Understanding the avalanche behaviour of a power device has become very important in these last years because it gives an indication of the maximum energy ratings which can be seen as an index of the device ruggedness. A good description of this behaviour is given by the static IV blocking characteristc. In order to avoid self heating, very relevant in high power devices, very short pulses of current have to be used, whose value can change from few milliamps up to tens of amps. The most used method to generate short pulses is the TLP (Transmission Line Pulse) test, which is based on charging the equivalent capacitance of a transmission line to high value of voltage and subsequently discharging it onto a load. This circuit let to obtain very short square pulses but it is mostly used for evaluate the ESD capability of semiconductor and, in this environment, it generates pulses of low amplitude which are not high enough to characterize the avalanche behaviour of high power devices . Advanced TLP circuit able to generate high current are usually very expensive and often suffer of distorption of the output pulse. In this article is proposed a simple, low cost circuit, based on a boosted-TLP configuration, which is capable to produce very square pulses of about one hundreds of nanosecond with amplitude up to some tens of amps. A prototype is implemented which can produce pulses up to 20A of amplitude with 200 ns of duration which can characterize power devices up to 1600V of breakdown voltage. Usage of microcontroller based logic make the circuit very flexible. Results of SPICE simulation are provided, together with experimental results. To prove the effectiveness of the circuit, the I-V blocking characteristics of two commercial devices, namely a 600V PowerMOS and a 1200V Trench-IGBT, are measured at different

  12. Implementations of quantum and classical gates with linear optical devices and photon number quantum non-demolition measurement for polarization encoded qubits

    International Nuclear Information System (INIS)

    Rosa Silva, Joao Batista; Ramos, Rubens Viana

    2006-01-01

    Aiming the construction of quantum computers and quantum communication systems based on optical devices, in this work we present possible implementations of quantum and classical CNOTs gates, as well an optical setup for generation and distribution of bipartite entangled states, using linear optical devices and photon number quantum non-demolition measurement

  13. Using metal complex-labeled peptides for charge transfer-based biosensing with semiconductor quantum dots

    Science.gov (United States)

    Medintz, Igor L.; Pons, Thomas; Trammell, Scott A.; Blanco-Canosa, Juan B.; Dawson, Philip E.; Mattoussi, Hedi

    2009-02-01

    Luminescent colloidal semiconductor quantum dots (QDs) have unique optical and photonic properties and are highly sensitive to charge transfer in their surrounding environment. In this study we used synthetic peptides as physical bridges between CdSe-ZnS core-shell QDs and some of the most common redox-active metal complexes to understand the charge transfer interactions between the metal complexes and QDs. We found that QD emission underwent quenching that was highly dependent on the choice of metal complex used. We also found that quenching traces the valence or number of metal complexes brought into close proximity of the nanocrystal surface. Monitoring of the QD absorption bleaching in the presence of the metal complex provided insight into the charge transfer mechanism. The data suggest that two distinct charge transfer mechanisms can take place. One directly to the QD core states for neutral capping ligands and a second to surface states for negatively charged capping ligands. A basic understanding of the proximity driven charge-transfer and quenching interactions allowed us to construct proteolytic enzyme sensing assemblies with the QD-peptide-metal complex conjugates.

  14. Development of a Handmade Conductivity Measurement Device for a Thin-Film Semiconductor and Its Application to Polypyrrole

    Science.gov (United States)

    Seng, Set; Shinpei, Tomita; Yoshihiko, Inada; Masakazu, Kita

    2014-01-01

    The precise measurement of conductivity of a semiconductor film such as polypyrrole (Ppy) should be carried out by the four-point probe method; however, this is difficult for classroom application. This article describes the development of a new, convenient, handmade conductivity device from inexpensive materials that can measure the conductivity…

  15. Method for sputtering a PIN amorphous silicon semi-conductor device having partially crystallized P and N-layers

    Science.gov (United States)

    Moustakas, Theodore D.; Maruska, H. Paul

    1985-07-09

    A high efficiency amorphous silicon PIN semiconductor device having partially crystallized (microcrystalline) P and N layers is constructed by the sequential sputtering of N, I and P layers and at least one semi-transparent ohmic electrode. The method of construction produces a PIN device, exhibiting enhanced electrical and optical properties, improved physical integrity, and facilitates the preparation in a singular vacuum system and vacuum pump down procedure.

  16. Isotope-based quantum information

    CERN Document Server

    G Plekhanov, Vladimir

    2012-01-01

    The present book provides to the main ideas and techniques of the rapid progressing field of quantum information and quantum computation using isotope - mixed materials. It starts with an introduction to the isotope physics and then describes of the isotope - based quantum information and quantum computation. The ability to manipulate and control electron and/or nucleus spin in semiconductor devices provides a new route to expand the capabilities of inorganic semiconductor-based electronics and to design innovative devices with potential application in quantum computing. One of the major challenges towards these objectives is to develop semiconductor-based systems and architectures in which the spatial distribution of spins and their properties can be controlled. For instance, to eliminate electron spin decoherence resulting from hyperfine interaction due to nuclear spin background, isotopically controlled devices are needed (i.e., nuclear spin-depleted). In other emerging concepts, the control of the spatial...

  17. Quantum dot spectroscopy

    DEFF Research Database (Denmark)

    Leosson, Kristjan

    Semiconductor quantum dots ("solid-state atoms") are promising candidates for quantum computers and future electronic and optoelectronic devices. Quantum dots are zero-dimensional electronic systems and therefore have discrete energy levels, similar to atoms or molecules. The size distribution...... of quantum dots, however, results in a large inhomogeneous broadening of quantum dot spectra. Work on self-assembled InGaAs/GaAs quantum dots will be presented. Properties of atom-like single-dot states are investigated optically using high spatial and spectral resolution. Single-dot spectra can be used...

  18. Quantum dot spectroscopy

    DEFF Research Database (Denmark)

    Leosson, Kristjan

    1999-01-01

    Semiconductor quantum dots ("solid state atoms") are promising candidates for quantum computers and future electronic and optoelectronic devices. Quantum dots are zero-dimensional electronic systems and therefore have discrete energy levels, similar to atoms or molecules. The size distribution...... of quantum dots, however, results in a large inhomogeneous broadening of quantum dot spectra.Work on self-assembled InGaAs/GaAs quantum dots will be presented. Properties of atom-like single-dots states are investigated optically using high spatial and spectral resolution. Single-dot spectra can be used...

  19. Plasmonic effects in metal-semiconductor nanostructures

    CERN Document Server

    Toropov, Alexey A

    2015-01-01

    Metal-semiconductor nanostructures represent an important new class of materials employed in designing advanced optoelectronic and nanophotonic devices, such as plasmonic nanolasers, plasmon-enhanced light-emitting diodes and solar cells, plasmonic emitters of single photons, and quantum devices operating in infrared and terahertz domains. The combination of surface plasmon resonances in conducting structures, providing strong concentration of an electromagnetic optical field nearby, with sharp optical resonances in semiconductors, which are highly sensitive to external electromagnetic fields, creates a platform to control light on the nanoscale. The design of the composite metal-semiconductor system imposes the consideration of both the plasmonic resonances in metal and the optical transitions in semiconductors - a key issue being their resonant interaction providing a coupling regime. In this book the reader will find descriptions of electrodynamics of conducting structures, quantum physics of semiconducto...

  20. Multifunctional semiconductor micro-Hall devices for magnetic, electric, and photo-detection

    Energy Technology Data Exchange (ETDEWEB)

    Gilbertson, A. M.; Cohen, L. F. [Blackett Laboratory, Imperial College London, Prince Consort Road, London SW7 2BZ (United Kingdom); Sadeghi, Hatef; Lambert, C. J. [Department of Physics, Lancaster University, Lancaster LA1 4YB (United Kingdom); Panchal, V.; Kazakova, O. [National Physical Laboratory, Teddington TW11 0LW (United Kingdom); Solin, S. A. [Blackett Laboratory, Imperial College London, Prince Consort Road, London SW7 2BZ (United Kingdom); Department of Physics and Institute for Materials Science and Engineering, Washington University in St. Louis, St. Louis, Missouri 63130 (United States)

    2015-12-07

    We report the real-space voltage response of InSb/AlInSb micro-Hall devices to local photo-excitation, electric, and magnetic fields at room temperature using scanning probe microscopy. We show that the ultrafast generation of localised photocarriers results in conductance perturbations analogous to those produced by local electric fields. Experimental results are in good agreement with tight-binding transport calculations in the diffusive regime. The magnetic, photo, and charge sensitivity of a 2 μm wide probe are evaluated at a 10 μA bias current in the Johnson noise limit (valid at measurement frequencies > 10 kHz) to be, respectively, 500 nT/√Hz; 20 pW/√Hz (λ = 635 nm) comparable to commercial photoconductive detectors; and 0.05 e/√Hz comparable to that of single electron transistors. These results demonstrate the remarkably versatile sensing attributes of simple semiconductor micro-Hall devices that can be applied to a host of imaging and sensing applications.