Growth of II-VI/III-V heterovalent quantum structures

Lattice-matched heterovalent II-VI/III-V semiconductor structures, such as quantum wells and double heterostructures consisting of ZnSe/GaAs and ZnTe/GaSb, are grown using single and dual-chamber molecular beam epitaxy systems by utilizing migration-enhanced epitaxy and a substrate temperature ramp method. Specific elemental overpressures are utilized after each epilayer growth to control the surface termination and to prevent defective III-VI compounds from forming at the heterovalent interfaces. Characterization using x-ray diffraction and transmission electron microscopy confirms sharp interfaces and coherent bonding between the heterovalent materials. Photoluminescence measurements show optical transitions from the heterovalent double heterostructures and quantum wells, as well as evidence for midgap defect states in the III-V layers. The III-V layers have a very low density of structural defects, but some stacking faults are observed in the II-VI layers. Published by the AVS.