Exciton Transfer between Localized States in CdS_1–<i>x</i>Se_<i>x</i> Alloys

Abstract

Abstract Picosecond time resolved luminescence is investigated of excitons localized by alloy potential fluctuations in CdS 1– x Se x . Time resolved luminescence spectra, as well as time decay curves and time integrated luminescence spectra of a CdS 0.36 Se 0.64 sample are fitted using a model in which transfer to lower energy states occurs through the tunnel effect assisted by acoustic phonons. The density of states is taken to be exponential with a characteristic energy, E 0 , equal to 2.2 meV. The radiative lifetime is 1.5 ns. The nonradiative lifetime due to transfer is inversely proportional to the number of available states at lower energy. Close agreement with the experimental results can also be found with a phenomenological model.