The photoluminescence of ZnOepitaxial film grown by MBEmethod was investigated. Some obvious interference fringes were observed in the reflection spectrum of ZnOfilm at room temperature due to Fabry-Perot interference

the Fabry-Perot interference indicates that optical quality of the sample is very good. Using the empirical equation of refractive index

the thickness of the film is estimated about 800 nm. The PL spectrum of the ZnOwas investigated under different excitation intensity using waveguide and backward configurations. In PL spectrum of waveguide configuration

six peaks at 383

390

392

406

438 and 502 nm were observed obviously. The peak at 392 nm appeared when excitation intensity is above certain values and then increased superlinearly. Wide spontaneous emission was observed in PL spectrum in backward configurations with low intensity. With the increasing of the excitation intensity

a new peak at 392 nm appeared. With further increasing of the excitation intensity

another new peak at 396 nm appeared

its intensity increases rapidly

its location shifts to red and width of the peak is broaden with the increasing of excitation intensity. It is thought that mechanism of the two peaks is identical

which is due to both defect scattering and exciton-exciton scattering. It was analyzed that there are the angle dependence of photoluminescence and striking difference in spontaneous spectrum between the two different configurations. The spectrum using waveguide configuration is more structured. Two effects may be responsible for the experiment results: one is the wavelength selection effect due to the absorption of guided-mode in asymmetric waveguide; the other is Fabry-Perot like interference of the grazing light in substrate (micro-cavity effect). The theory results of the two different explanations are thought to be equal in the film plane.