Photoluminescence lifetime of Al-doped ZnO films in visible region

ZnO and Al-doped ZnO films have been deposited on quartz substrates by ultrasonically assisted chemical vapor deposition technique. Photoluminescence (PL) spectra of the films reveal that Al doping leads to suppression of defect related visible band. Time resolved photoluminescence studies have been carried out for the measurement of lifetime of deep level luminescence. The decay of PL intensity with time has been found to follow biexponential behavior. The relative contributions of fast decay component (τ1)(τ1) and slow decay component (τ2)(τ2) in total decay process are found to be ∼99% and ∼1% respectively. The values of τ1τ1 and τ2τ2 are found to decrease with Al doping in ZnO film. The decrease of both τ1τ1 and τ2τ2 is attributed to increase in non-radiative recombination due to reduction in grain sizes and the decrease in radiative recombination due to suppression of defects.