Temperature-Dependent Excitonic Luminescence in ZnO Thin Film Grown by Metal Organic Chemical Vapor Deposition

In this study. the excitonic luminescence behaviors of ZnO thin films in the temperature range of 10 -300K were investigated The photoluminescence (PL) spectrum exhibits the bound-exciton emission and the donor-acceptor recombination accompanying its multiphonon replicas at low temperatures. The observed features exhibit redshift with an increase in temperature, and the temperature dependence of the peak position was analyzed by the Varshni empirical expression. The study showed the dominant presence of bound excitonic transition below 160K or free excitonic transition at higher temperatures for the observed PL spectrum. The free exciton emission can be observed up to room temperature The Debye temperature of ZnO was evaluated by taking into account the elastic constants of ZnO and utilized as a parameter in the Varshni empirical expression giving an accurate description of the free exciton emission behavior up to room temperature (C) 2009 The Japan Society of Applied Physics