Search query: Quantum size effect in three-dimensional microscopic semiconductor crystals

Related papers:

abstract: The exciton absorption spectrum of microscopic CuCl crystals grown in a transparent dielectric matrix has been studied. The size of the microscopic crystals was varied in a controlled manner from several tens of angstroms to hundreds of angstroms. There is a short wave shift (of up to 0.1 eV) of the exciton absorption lines, caused by a quantum size effect.
author_names: A I Ekimov

Alexei A Onushchenko
title: Quantum size effect in three dimensional microscopic semiconductor crystals
year: 1981

abstract: Current research into semiconductor clusters is focused on the properties of quantum dots fragments of semiconductor consisting of hundreds to many thousands of atoms with the bulk bonding geometry and with surface states eliminated by enclosure in a material that has a larger band gap. Quantum dots exhibit strongly size dependent optical and electrical properties. The ability to join the dots into complex assemblies creates many opportunities for scientific discovery.
author_names: A Paul Alivisatos
title: Semiconductor Clusters, Nanocrystals, and Quantum Dots
venue: Science
year: 1996

abstract: to Kinetics and Many Body Theory. Boltzmann Equation. Numerical Solutions of the Boltzmann Equation. Equilibrium Green Function Theory. Nonequilibrium Many Body Theory. Contour Ordered Green Functions. Basic Quantum Kinetic Equations. Boltzmann Limit. Gauge Invariance. Quantum Distribution Functions. Quantum Transport in Semiconductors. Linear Transport. Field Dependent Green Functions. Optical Absorption in Intense THz Fields. Transport in Mesoscopic Semiconductor Structures. Time Dependent Phenomena. Theory of Ultrafast Kinetics in Laser Excited Semiconductors. Optical Free Carrier Interband Kinetics in Semiconductors. Interband Quantum Kinetics with LO Phonon Scattering. Two Pulse Spectroscopy. Coulomb Quantum Kinetics in a Dense Electron Hole Plasma. The Buildup of Screening. Femtosecond Four Wave Mixing with Dense Plasmas.
author_names: Hartmut Haug

A P Jauho
title: Quantum Kinetics in Transport and Optics of Semiconductors
year: 2004

abstract: With their bright, photostable fluorescence, semiconductor quantum dots show promise as alternatives to organic dyes for biological labeling. Questions about their potential cytotoxicity, however, remain unanswered. While cytotoxicity of bulk cadmium selenide (CdSe) is well documented, a number of groups have suggested that CdSe QDs are cytocompatible, at least with some immortalized cell lines. Using primary hepatocytes as a liver model, we found that CdSe core QDs were indeed acutely toxic under certain conditions. Specifically, we found that the cytotoxicity of QDs was modulated by processing parameters during synthesis, exposure to ultraviolet light, and surface coatings. Our data further suggests that cytotoxicity correlates with the liberation of free Cd2+ ions due to deterioration of the CdSe lattice. When appropriately coated, CdSe core QDs can be rendered non toxic and used to track cell migration and reorganization in vitro. Our results inform design criteria for the use of QDs in vitro and especially in vivo where deterioration over time may occur.
author_names: Austin M Derfus

Warren C W Chan

Sangeeta N Bhatia
title: Probing the Cytotoxicity Of Semiconductor Quantum Dots.
venue: Nano letters
year: 2004

abstract: This revised second edition on the "Quantum Theory of the Optical and Electronic Properties of Semiconductors" presents the basic elements needed to understand and engage in research in semiconductor physics. In this revised second edition misprints are corrected and some new and more detailed material is added. In order to treat the valence band structure of semiconductors, an introduction to the k.p. theory and the related description in terms of the Luttinger Hamiltonian is included. An introductory chapter on mesoscopic semiconductor structures discussing the modifications of the envelope function approximation caused by the spatial quantum confinement is also included. Many results are developed in parallel first for bulk material, and then for quasi two dimensional quantum wells, and for quasi one dimensional quantum wires. Semiconductor quantum dots are treated in a separate chapter. The discussion of time dependent and coherent phenomena in semiconductors has been considerably extended by including a section dealing with the theoretical description of photon echoes in semiconductors. A new chapter on magneto absorption has been added, in which magneto excitons and magneto plasmas in two dimensional systems are discussed. The chapter on electron kinetics due to the interaction with longitudinal optical phonons has been extended. The material is presented in sufficient detail for graduate students and researchers who have a general background in quantum mechanics, and is aimed at solid state physicists, engineers, materials and optical scientists.
author_names: Hartmut Haug

Stephan W Koch
title: Quantum Theory of the Optical and Electronic Properties of Semiconductors
year: 1990

abstract: We show that the quantum spin Hall (QSH) effect, a state of matter with topological properties distinct from those of conventional insulators, can be realized in mercury telluride cadmium telluride semiconductor quantum wells. When the thickness of the quantum well is varied, the electronic state changes from a normal to an "inverted" type at a critical thickness dc. We show that this transition is a topological quantum phase transition between a conventional insulating phase and a phase exhibiting the QSH effect with a single pair of helical edge states. We also discuss methods for experimental detection of the QSH effect.
author_names: Bogdan Andrei Bernevig

Taylor L Hughes

Shou-Cheng Zhang
title: Quantum Spin Hall Effect and Topological Phase Transition in HgTe Quantum Wells
venue: Science
year: 2006

abstract: We report free standing atomic crystals that are strictly 2D and can be viewed as individual atomic planes pulled out of bulk crystals or as unrolled single wall nanotubes. By using micromechanical cleavage, we have prepared and studied a variety of 2D crystals including single layers of boron nitride, graphite, several dichalcogenides, and complex oxides. These atomically thin sheets (essentially gigantic 2D molecules unprotected from the immediate environment) are stable under ambient conditions, exhibit high crystal quality, and are continuous on a macroscopic scale.
author_names: Kostya S Novoselov

Da Jiang

Fred Schedin

Timothy J Booth

V V Khotkevich

S V Morozov

Andre K Geim
title: Two dimensional atomic crystals.
venue: Proceedings of the National Academy of Sciences of the United States of America
year: 2005

abstract: 1. Peculiarities of d=1 2. Bosonization 3. Luttinger liquids 4. Refinements 5. Microscopic methods 6. Spin 1/2 chains 7. Interacting fermions on a lattice 8. Coupled fermionic chains 9. Disordered systems 10. Boundaries and isolated impurities 11. Significant others A. Basics of many body B. Not so important fine technical points C. Correlation functions D. Bosonization directory E. Sine Gordon F. Numerical solution
author_names: Thierry Giamarchi
title: Quantum physics in one dimension
year: 2004

abstract: We study the effects of spin orbit interactions on the low energy electronic structure of a single plane of graphene. We find that in an experimentally accessible low temperature regime the symmetry allowed spin orbit potential converts graphene from an ideal two dimensional semimetallic state to a quantum spin Hall insulator. This novel electronic state of matter is gapped in the bulk and supports the transport of spin and charge in gapless edge states that propagate at the sample boundaries. The edge states are nonchiral, but they are insensitive to disorder because their directionality is correlated with spin. The spin and charge conductances in these edge states are calculated and the effects of temperature, chemical potential, Rashba coupling, disorder, and symmetry breaking fields are discussed.
author_names: C L Kane

Eugene J Mele
title: Quantum spin Hall effect in graphene.
venue: Physical review letters
year: 2005

abstract: We demonstrated coherent control of a quantum two level system based on two electron spin states in a double quantum dot, allowing state preparation, coherent manipulation, and projective readout. These techniques are based on rapid electrical control of the exchange interaction. Separating and later recombining a singlet spin state provided a measurement of the spin dephasing time, T2* of ~10 nanoseconds, limited by hyperfine interactions with the gallium arsenide host nuclei. Rabi oscillations of two electron spin states were demonstrated, and spin echo pulse sequences were used to suppress hyperfine induced dephasing. Using these quantum control techniques, a coherence time for two electron spin states exceeding 1 microsecond was observed.
author_names: Jason R Petta

A C Johnson

J M Taylor

E A Laird

Amir Yacoby

Mikhail D Lukin

Charles M Marcus

Micah P Hanson

Arthur C Gossard
title: Coherent Manipulation of Coupled Electron Spins in Semiconductor Quantum Dots
venue: Science
year: 2005