Excitation and Recombination Processes in rare Earth Doped II–VI Semiconductors

Abstract

AbstractRare Earth (RE) doped II–VI semiconductors are currently used for production of thin film light emitting electroluminescence devices. The excitation and recombination processes in RE activated wide band gap II–VI semiconductors (ZnS, ZnSe, SrS and CaS) are reviewed. Mechanisms relevant for obtaining bright photoluminescence (energy transfer processes, RE ionisation and exciton binding), electroluminescence (impact excitation and impact ionisation) and cathodoluminescence are described based on the recent experimental results. Efficiency of the light emission from RE doped II–VI materials is limited by several processes of nonradiative recombination. The Auger-type energy transfer processes and electric field- or thermally-activated processes responsible for 4f-4f nonradiative recombination of RE ions are discussed.