Investigation of the interfacial quality and the influence of different substrates in ZnSe homoepitaxy

ZnSe substrates grown by the seeded chemical vapour transport and recrystallization as well as by the Bridgman method are compared for their use in molecular beam epitaxy. Intrinsic and extrinsic defects were analysed by low-temperature photoluminescence and especially by electron-paramagnetic-resonance. The transition region between substrate and epitaxial layers is studied by cross-sectional transmission electron microscopy. The defect densities in the interface are found to be lower than for heteroepitaxial layers on GaAs substrates. The strained multi-quantum-well region of homoepitaxial light-emitting diodes is also investigated. They were tested at room temperature and emit sharply at 490 nm with a full-width at half-maximum of 51 meV.