Electronic phase diagram of single-element silicon "strain" superlattices.
The evidence that the band gap of Si changes significantly with strain suggests that by alternating regions of strained and unstrained Si one creates a single-element electronic heterojunction superlattice (SL), with the carrier confinement defined by strain rather than by the chemical differences in conventional compositional SLs. Using first-principles calculations, we map out the electronic phase diagram of a one-dimensional pure-silicon SL. It exhibits a high level of phase tunability, e.g., tuning from type I to type II. Our theory rationalizes a recent observation of a strain SL in a Si nanowire and provides general guidance for the fabrication of single-element strain SLs.
Liu
Zheng
Z
Institute for Advanced Study, Tsinghua University, Beijing, China, 100084.
Wu
Jian
J
Duan
Wenhui
W
Lagally
Max G
MG
Liu
Feng
F