Upper-conduction-band effects in heavily strained low-dimensional zinc-blende semiconductor systems.

Abstract

We show the existence of a stress-induced coupling between upper-conduction-band states and valence-band states in bulk zinc-blende semiconductors and in their strained-layer low-dimensional systems. This coupling is calculated by an empirical tight-binding method which exactly includes the full crystal symmetry of the strained semiconductor compounds. As an application, we report a study of CdTe-ZnTe superlattices having thin ZnTe layers which exhibit an anomalously high energy for the electron to light-hole transition. We show that the large shift of this transition is well accounted for via mixing between valence and upper-conduction bands.