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Zero Valley Splitting at Zero Magnetic Field for Strained Si/SiGe Quantum Wells

Published online by Cambridge University Press:  01 February 2011

Seungwon Lee
Affiliation:
[email protected], Jet Propulsion Laboratory, High Capability Computing and Modeling, 4800 Oak Grove Dr. M/S 169-315, Pasadena, CA, 91109, United States, 818-393-7720
Paul von Allmen
Affiliation:
[email protected], Jet Propulsion Laboratory, 4800 Oak Grove Drive, Pasadena, CA, 91109, United States
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Abstract

The electronic structure for a strained silicon quantum well grown on a tilted SiGe substrate is calculated using an empirical tight-binding method. For a zero substrate tilt angle the two lowest minima of the conduction band define a non-zero valley splitting at the center of the Brillouin zone. A finite tilt angle for the substrate results in displacing the two lowest conduction band minima to finite k0 and -k0 in the Brillouin zone with equal energy. The vanishing of the valley splitting for quantum wells grown on tilted substrates is found to be a direct consequence of the periodicity of the steps at the interfaces between the quantum well and the buffer materials.

Type
Research Article
Copyright
Copyright © Materials Research Society 2007

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