ZnO/P-Si heterojunctions are fabricated by pulsed laser deposition of ZnO films on P-Si substrates.The substrate temperatures of 400 ℃,500 ℃,550 ℃ and 600 ℃ are taken for the ZnO film deposition.All the heterojunctions show typical rectifying behaviors and the reverse dark current increases with the substrate temperature.The sample prepared at 550 ℃ shows the best photoelectric effects.There are different I-V characteristics as the ZnO/P-Si heterojunction is exposed to visible and ultraviolet (UV) photons.The photocurrent increases rapidly in the initial several voltages,but slowly beyond a certain reverse bias voltage.When the sample is illuminated by UV photon,the photocurrents show a gradual increase with the bias.According to the transmittance spectra of the ZnO films,it is thought that the electron-hole pairs are induced in the different depletion of the heterojunction for the visible and UV photons.