ZnO thin films were grown on single-crystal Si(100) substrate by pulsed laser deposition (PLD) technique. The crystal structure and electrical properties were investigated as a function of oxygen partial pressure. Results indicate that highly c-axis oriented ZnO films can be obtained at all oxygen pressure range. With the increase of oxygen pressure, the crystallinity is further enhanced and the film presents smooth, uniform and dense packed columnar microstructure. Hall measurement indicates the resistivity of ZnO films increases with oxygen pressure. ZnO film grown at optimum conditions is employed to fabricate the MSM structured UV detectors with Ti/Pt/Au interdigital electrode configuration by standard photolithography and lift-off technique. The I-V characteristic and photo response measurement indicate a good ohmic contact between the ZnO film and electrode, and significant photoresponsivity under ultraviolet illumination.