Epitaxial ZnSe and Cubic GaN: Wide-Band-Gap Semiconductors with Similar Properties?

Due to a number of interesting applications, the interest in optoelectronic devices emitting coherent light with short wavelengths, such as blue or ultraviolet light emitting laser diodes (LDs) has increased dramatically. Two different approaches, one using II–VI wide-band-gap semiconductors (ZnSe-based devices) and one using III-nitrides (GaN-based devices), have been used to reach the goal of long-lifetime, continuously working LDs. Currently, ZnSe-based multilayer structures grown on lattice matched GaAs substrates are the more mature material for LD application. However, progress has been achieved also with the development of GaN-based, blue light emitting LDs. The III-nitrides crystallize in the wurtzite (hexagonal) crystal structure. This is an obstacle for the production of cleaved laser cavities. The growth of the metastable, zincblende (cubic) modification of group-III-nitrides, which may be an alternative material for the realization of LDs with cleaved cavities has been improved in the last few years. In this paper, some physical properties related to LD application of cubic II–VI and III–V wide-band-gap semiconductors are compared.