Exciton Transfer between Localized States in CdS1–xSex Alloys

TLDR: In this article, the authors investigated the effect of excitons localized by alloy potential fluctuations in CdS1-xSex on the time resolved luminescence spectra.

Abstract: Picosecond time resolved luminescence is investigated of excitons localized by alloy potential fluctuations in CdS1–xSex. Time resolved luminescence spectra, as well as time decay curves and time integrated luminescence spectra of a CdS0.36Se0.64 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, E0, 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. Nous etudions la luminescence resolue en temps due aux excitons localises par les fluctuations de potential d'alliage dans CdS1–xSex. Les spectres de luminescence resolue en temps, les courbes de decroissance temporelle ainsi que les spectres de luminescence integree en temps d'un echantillon de composition CdS0,36Se0,64 sont ajustes en utilisant le modele de transfert par effet tunnel assiste par phonon acoustique. La densite d'etats decroit exponentiellement avec une energie caracteristique E0 = 2,2 meV. Le temps de vie radiatif est egal a 1,5 ns. Le temps de vie non-radiatif dǔ au transfert est inversement proportionnel au nombre d'etats disponsibles a plus basse energie. Un modele phenomenologique donne egalement un bon accord avec les resultats experimentaux.