Due to their wide potential applications in short-wavelength optoelectronic devices

ZnO and it’s alloy have become one of the main topics in the research field of optoelectronic materials and devices.Although high quality ZnO films are available due to the improvement of material growth techniques

the luminescence behavior

mechanism and their relations with the structure of material are still unclear.Much work is needed for further understanding of the optical properties of ZnO films.In this paper

the photoluminescence properties of ZnO film grown by Laser-MBE method have been experimentally investigated.The optical characterization methods we used include temperature-dependent and excitation-intensity-dependent photoluminescence.When using YAG pulse laser as the excitation source

a new emission band appeared on the low energy side

it might be originated from electron-hole-plasma(EHP) recombination.Stimulated emission can be detected both from the surface and the edge of the film

this shows that the film contains certainty quantity of defects.However

the spectrum excited by an Xe lamp under room temperature contains two emission bands: the violet band with a peak at 381 nm and the blue-green band with a peak at 450 nm

based on the information given by the PLE spectrum

a simple model for blue emission in ZnO was proposed.By comparison of the different spectrum using different excitation sources

it is concluded that the violet band emission may require certain high excitation intensity

and the blue band emission saturates rapidly with the increasing excitation intensity.