Wide-gap II-VI heterostructures

New advances in epitaxial growth techniques have contributed to an improved understanding of the properties of II-VI materials and their alloys. The creation of novel heterojunctions, quantum well structures, and strained-layer superlattices, composed of II-VI/III-V and II-VI/II-VI multilayers, can be attributed to their successful epitaxial growth by molecular beam epitaxy (MBE). The objective of this paper is to discuss some recent advances in the growth of II-VI/III-V and II-VI/II-VI heterostructures, with emphasis on two particular topics. In the first, pseudomorphic epilayer/epilayer heterojunctions consisting of ZnTe on AlSb, a configuration with potential for the development of injection light emitting devices, have been grown by MBE. Microstructural and optical evaluation has indicated a high structural quality. The second topic describes the use of MBE for the growth of novel structures incorporating a previously hypothetical magnetic semiconductor, the zincblende phase of MnTe. Characterization using TEM and X-ray diffraction reveals only the zincblende phases of MnTe. Whereas bulk crystals of MnTe having a NiAs structure with a bandgap of 1.3 eV, the zincblende phase exhibits a bandgap of 3.2 eV. Single quantum well structures incorporating zincblende MnTe exhibit 2D electron and hole confinement in both CdTe and ZnTe quantum wells, and serve to confirm the zincblende MnTe bandgap at 3.2 eV.