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Effective Mass Approximation (effective + mass_approximation)

Distribution by Scientific Domains
Physics and Astronomy100%

Selected Abstracts

Auger recombination in silicon nanocrystals embedded in SiO2 wide band-gap lattice

PHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 11 2008
M. Mahdouani
Abstract We calculate the ground and excited electron and hole levels in spherical Si nanocrystals (quantum dots) embedded within SiO2 in a multiband effective mass approximation. The obtained energies of electron and hole are used to estimate the Auger Recombination (AR) lifetime in Si Nanocrystals (NCs). The excited electron, excited hole and biexciton AR types are considered. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Binding energy of a hydrogenic donor impurity in an ellipsoidal finite-potential quantum dot

PHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 7 2007
M. Barati
Abstract In this article, the binding energy of a hydrogenic donor impurity in weakly oblate Ellipsoidal Quantum Dot (EQD), using the perturbation theory within the framework of effective mass approximation, is investigated. In this regard, the binding energies of 1S, 2S and 2P0 states for GaAs/AlxGa1,xAs structures, as functions of the dot radius and ellipticity constant, are calculated. Results show that variations of binding energies of a hydrogenic impurity with respect to the dot dimension are similar to the case of Spherical Quantum Dot (SQD). In addition, it is found that the binding energy is inversely proportional to the ellipticity constant. This behavior is more profound for 2P0 state, where, depending on the dot's dimensionality and ellipticity, the binding energy may become negative. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Photoreflectance investigations of energy level structure of InAs quantum dashes embedded in InGaAs/InGaAlAs quantum well grown on InP substrate

PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 11 2006
W. Rudno-Rudzi
Abstract Photoreflectance (PR) and photoluminescence measurements have been performed on molecular beam epitaxy grown InAs quantum dashes (QDash) of various sizes, embedded in In0.53Ga0.47As/In0.53Ga0.23Al0.24As quantum well (QW), grown on InP substrate. PR response from all relevant parts of the structure, i.e InAs/In0.53Ga0.47As QDashes, InAs/In0.53Ga0.47As/In0.53Ga0.23Al0.24As QW, and In0.53Ga0.23Al0.24As barriers, has been obtained. The lowest energy transition related to the ground state transition in QDashes shifts towards red with the increase in QDash sizes (amount of deposited InAs material) reaching wavelengths longer than for structures without the intermediate QW. The experimental data on the energies of optical transitions combined with the numerical calculation within the effective mass approximation has allowed determining the energy level structure of the entire system, including the values of conduction band offset between InGaAs and InGaAlAs layers. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Electronic structure of three-dimensional triangular torus-shaped quantum rings under external magnetic fields

PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 4 2003
Yiming Li
Abstract In this paper, we calculate the electron,hole energy states and the magnetization for InAs/GaAs triangular torus-shaped (TTS) quantum rings in a magnetic field. Our three-dimensional (3D) model considers (i) the effective one-band Hamiltonian approximation, (ii) the position- and energy-dependent quasi-particle effective mass approximation, (iii) the finite hard wall confinement potential, and (iv) the Ben Daniel-Duke boundary conditions. This model is solved numerically with the nonlinear iterative method to obtain the "self-consistent" solutions. We investigate the electron-hole energy spectra versus magnetic field for two different ring widths: R0 = 20 and 50 nm, and find that they strongly depend on the ring shape and size. Since the magnetic field penetrates into the inside region of the nonsimply connected ring, the electron (hole) transition energy between the lowest states versus magnetic field oscillates nonperiodically and is different from that of quantum dots. We find the magnetization at zero temperature is a negative function, saturates, and oscillates nonperiodically when the magnetic field increases. [source]