Luminescence of CdSe and CdS and the Influence of Defects

摘要

Spontaneous luminescence of 'pure' CdSe and CdS at low temperature, excited by mercury lamp, shows a number of peaks attributed to bound exciton and free exciton recombination mechanisms. Temperature dependence (6K to 80K) of various emission lines has been determined to characterize the transition mechanisms responsible for them. Stimulated emission of a number of CdSe platelets has been studied as function of exciton intensity and temperature by using Ga(As,P) pulsed laser diode as pump. These results indicate that there is no unique origin of the stimulated emission at low temperatures. A number of transition mechanisms, involving free and bound excitons, simultaneously compete and generate stimulated emission dependent on the level of excitation and the platelet being excited. Several of the stimulated peaks appear to be correlated to the spontaneous lines resulting from bound exciton transitions accompanied by emission of an LO phonon. (Author)