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Intervalley splitting and intersubband transitions in n-type Si/SiGe quantum wells: Pseudopotential vs. effective mass calculation

Valavanis, A, Ikonic, Z and Kelsall, RW (2007) Intervalley splitting and intersubband transitions in n-type Si/SiGe quantum wells: Pseudopotential vs. effective mass calculation. Physical Review B (Condensed Matter), 75 (20). pp.205332 . ISSN 0163-1829

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Abstract

Intervalley mixing between conduction band states in low-dimensional Si/SiGe heterostructures induces splitting between nominally degenerate energy levels. The symmetric double-valley effective mass approximation (DVEMA) and the empirical pseudopotential method (EPM) are used to find the electronic states in different types of quantum wells. A reasonably good agreement between the two methods is found, with the former being much faster computationally. Aside from being an oscillatory function of well width, the splitting is found to be almost independent of in-plane wave vector, and an increasing function of the magnitude of interface gradient. Whilst the model is defined for symmetric envelope potentials, it is shown to remain reasonably accurate for slightly asymmetric structures such as a double quantum well, making it acceptable for simulation of multilayer intersubband optical devices. Intersubband optical transitions are investigated under both approximations and it is shown that in most cases valley splitting causes linewidth broadening, although under extreme conditions, transition line doublets may result.

Item Type: Article
Copyright, Publisher and Additional Information: © 2007 The American Physical Society. This is an author produced version of a paper published in Physical Review B. Uploaded in accordance with the publisher's self-archving policy.
Keywords: Quantum Wells, silicon, elemental semiconductors, Ge-Si alloys, semiconductor quantum wells, effective mass, conduction bands
Institution: The University of Leeds
Academic Units: The University of Leeds > Faculty of Engineering (Leeds) > School of Electronic & Electrical Engineering (Leeds) > Institute of Microwaves and Photonics (Leeds)
Depositing User: Dr Alexander Valavanis
Date Deposited: 15 Jun 2011 09:00
Last Modified: 24 Jun 2014 09:41
Published Version: http://link.aps.org/abstract/PRB/v75/e205332
Status: Published
Publisher: American Institute of Physics
Refereed: Yes
URI: http://eprints.whiterose.ac.uk/id/eprint/42943

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