Exciton-polariton dynamics and photoluminescence line shapes in cadmium telluride.

Abstract

Time-resolved and steady-state photoluminescence (PL) data on excitonic polaritons in CdTe are presented and analyzed in terms of polariton formation, transport, and relaxation processes. The sample-to-sample variation in the polariton line shape and the shapes of the various polariton phonon sideband indicates that there is substantial polariton emission from below the bottleneck region, which shows that transport effects dominate the polariton line shape. Time-resolved PL data from the polariton band show that both formation and decay rates vary with time and k state, producing complex polariton decay waveforms. Polariton formation at the bottom of the band persists for up to 3 ns after optical excitation. Bound-exciton lifetimes can be extracted from the bound-exciton PL decay waveforms if the time dependence of the binding-polariton population is known. These results are compared with previous experimental and theoretical studies of polariton dynamics.