Electronic structure of cadmium-telluride–zinc-telluride strained-layer superlattices under pressure

The pressure dependence of the low-temperature photoluminescence of CdTe/ZnTe strained-layer superlattices is reported, up to the phase transition of the structure at about 6 GPa. The superlattices can be simultaneously type I for heavy holes and type II for light holes. A theoretical fit to the pressure dependence of the type-I and type-II luminescence lines confirms a number of bulk and superlattice parameters. In particular, the results are consistent with a treatment of the band structure in the framework of the envelope-function approach. The ground valence-band state is found to be the first light-hole valence subband. The valence-band offset has been fitted to be pressure dependent; we found 75+4.5P meV. Under pressure, a type-I--type-II transition is observed, due to a crossover in the valence band of the superlattice.