[001]-STRAIN-INDUCED BAND MIXING IN ZINCBLENDE SEMICONDUCTORS - INTRAVALENCE VERSUS UPPER-CONDUCTION-VALENCE BAND EFFECTS

We study theoretically the possible band mixings induced by a biaxial strain perpendicular to the [001] axis, at the Γ point of zinc-blende semiconductors. Simple group-theory arguments reveal that the usually labeled light-hole state is mixed both with the split-off valence band (intravalence band mixing) and with the upper conduction band (upper-conduction-valence interband mixing). This latter coupling often has been previously neglected in former studies concerning strained compounds and heterostructures. These mixings are related to the interband deformation potentials. The competition of this upper-conduction-valence interband mixing with the intravalence band mixing is analyzed as a function of the spin-orbit energy and of the ionicity at the zone center. Effects of the upper conduction bands comprise at least 30% for usual semiconductors. We specify the conditions and the experimental situations for which it must be taken into account. © 1994 The American Physical Society.