Analytical and numerical studies on strain and crystal-orientation effects on the valence bands in hexagonal semiconductor layers and quantum wells

Abstract

The effects of strain and crystal orientation on the effective masses of holes in bulk layers and in quantum wells (QWs) of hexagonal semiconductors are studied systematically within a six-band effective-mass theory. Analytical expressions of the effective masses in strained bulk layers are derived in some specific cases. The sum rule among the inverse effective masses in bulk layers as well as that among the inverse quantization masses in QWs is proved. Numerically calculated results on GaN bulk layers grown on non-polar planes reveal that strain modifies anisotropy in zone-center effective masses. The quantization energies of holes in unstrained GaN QWs are calculated as a function of the growth direction. The calculated results are also shown for quantization masses in (0 0 0 1) and ( 1 0 1 ¯ 0 ) strained QWs as functions of the well width and strain.