Subnanosecond spectroscopy of disorder-localized excitons in CdS0.53Se0.47

Abstract

Time-resolved luminescence spectra from excitons in Cd${\mathrm{S}}_{0.53}$ ${\mathrm{Se}}_{0.47}$ at 2 K with 250 psec resolution reveal line narrowing at short times, followed by broadening and a shift towards lower energy, during the first few nanoseconds. We interpret the spectral diffusion as exciton transfer between states localized as a result of random potential fluctuations of the mixed crystal. The variation of luminescence decay kinetics with temperature suggests that a gradual transition from localized to extended states exists within a disorder-broadened exciton band.