UPPER-CONDUCTION-BAND EFFECTS IN HEAVILY STRAINED LOW-DIMENSIONAL ZINCBLENDE SEMICONDUCTOR SYSTEMS

We show the existence of a stress-induced coupling between upper-condu ction-band states and valence-band states in bulk zinc-blende semicond uctors and in their strained-layer low-dimensional systems. This coupl ing is calculated by an empirical tight-binding method which exactly i ncludes the full crystal symmetry of the strained semiconductor compou nds. As an application, we report a study of CdTe-ZnTe superlattices h aving thin ZnTe layers which exhibit an anomalously high energy for th e electron to light-hole transition. We show that the large shift of t his transition is well accounted for via mixing between valence and up per-conduction bands.