Si inversion layers with a sixfold valley degeneracy

Abstract

The inversion layer in n-channel MOSFETs on (111) Si, prepared with high temperature annealing in Ar and in N 2 ambient, has the long expected sixfold valley degeneracy. This sixfold level splits into a two-fold and a four-fold under the influence of an applied uniaxial stress. Our preliminary results show a splitting of ∼4.5 × 10 −9 meV cm 2 dyn , with stress along [110], and a conductivity anisotropy of ∼4 in the two-fold valley degenerate state.