Temperature-dependent exciton dynamics in a ZnO thin film

Abstract

We measured the temperature-dependent photoluminescence (PL) decay time of the mixed system of free exciton (FX) and donor-bound exciton (DX0) in a ZnO thin film. From the measured cw PL spectra, we also calibrated the individual spectral widths and integrated PL intensities of FX and DX0 by fitting the spectra with four Lorentzian functions. The radiative lifetime of the mixed system was then calibrated based on the thermal quenching rate of the total integrated PL intensity of the system. With the system radiative lifetime data, FX radiative lifetimes were estimated by using a theoretical relation between the lifetime and the spectral width. From the results of FX radiative lifetime, we calibrated the DX0 radiative lifetimes by considering the emission intensity ratio between FX and DX0. The results support our model that the DX0 radiative behavior is similar to that of FX when the thermal energy is smaller than the donor binding energy.