ZnSe-based laser diodes and LEDs grown on ZnSe and GaAs substrates

CdZnSSe quaternary and CdZnSe ternary quantum wells have been compared concerning their thermal stability. The Cd diffusion started from the II-VI/III-V interface side, and was suppressed by introducing S in the quantum well region. It was found that these CdZnSSe wells have advantages for application in laser diodes compared to the commonly used CdZnSe wells. A laser diode with a CdZnSSe quantum well has operated with low threshold current density at room temperature under pulsed operation. Since homoepitaxy on ZnSe substrates can avoid the interface problem caused by the heterovalency between ZnSe and GaAs, light-emitting diode structures were grown on a conducting ZnSe:I substrate. Electroluminescence from the structures showed two peaks, a band-edge emission and a broad deep-level emission. It was found that the deep-level emission was internal photoluminescence from the ZuSe substrates excited by the band-edge emission.