Makoto Konagai

Wide Bandgap II-VI Compound Superlattices Prepared by MBE and MOMBE

II–VI compound semiconductors, especially ZnS, ZnSe and ZnTe, are considered to be the promising materials for LEDs and laser diodes emitting blue light. Recently, ZnSe pn diodes have been successfully grown on GaAs by MOCVD using lithium nitride as a p-type dopant. To make a pn junction in the wide bandgap II–VI compound semiconductors, we selected a ZnSe-ZnTe superlattice structure2. We have prepared ZnSe-ZnTe strained-layer superlattices(SLS) by MBE with a modulation doping technique3. The concept of producing both p and n-type conduction using a superlattice is illustrated in Fig.1. Modulation doping of the ZnSe layers with Ga is thought to result in a n-type SLS. P-type SLS can similarly be obtained by modulation doping with Sb in the ZnTe layers. This opens up the possibility of fabricating a pn junction by using ZnSe-ZnTe SLSs. The modulation doping technique can be also applied to the ZnS(ZnSSe)- ZnTe system.