The metal-semiconductor-metal (MSM) structured ZnO photodetectors with same electrode spacings are made by radio frequency magnetron sputtering. A study of the thermal annealing effects on photodetectors with sequential annealing temperature (300, 400, 500 and 600 ℃).The responsivity of the photodetector was enlarged greatly after annealing the MSM device. Meanwhile, the enhancement in the dark current that resulted from the experiment was accompanied by the increasing annealing temperature. These results demonstrate that a simple route to improve the responsivities of photodetectors can be realized easily by annealing the devices.
Two sets of ZnO ultraviolet photodetectors were fabricated on the quartz and sapphire, respectively. Because of the different lattice matching of the substrate for the ZnO, the ZnO thin film based on the high matching substrate has a better crystalline quality and it is more sensitive to ultraviolet light. The ultraviolet photodetector based on the sapphire not only has a stronger absorption for the light, but also has a higher photo response than the ultraviolet photodetector based on the quartz. Which will have a profound influence for fabricating the excellent photodetectors.