Valley degeneracies in (111) silicon quantum wells
Date of this Version1-26-2009
APPLIED PHYSICS LETTERS 94, 042101 (2009)
This document has been peer-reviewed.
(111) silicon quantum wells have been studied extensively, yet no convincing explanation exists for the experimentally observed breaking of sixfold valley degeneracy into two- and fourfold degeneracies. Here, systematic sp(3)d(5)s(*) tight-binding and effective mass calculations are presented to show that a typical miscut modulates the energy levels, which leads to breaking of sixfold valley degeneracy into two lower and four raised valleys. An effective mass based valley-projection model is used to determine the directions of valley minima in tight-binding calculations of large supercells. Tight-binding calculations are in better agreement with experiments compared to effective mass calculations.
Nanoscience and Nanotechnology