Zexuan Guo

Improving the performance of the ultraviolet photodetectors based on the ZnO thin film by changing the substrate

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.

ZnO ultraviolet photodetector based metal-semiconductor-metal structure

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.

Controlled response wavelength shifting in ultraviolet photodetectors based on double-layer films

By integrating ZnO and MgZnO films onto a quartz substrate (both films with the same growth time), the ultraviolet photodetectors (Au/ZnO/MgZnO/SiO2 and Au/MgZnO/ZnO/SiO2 structured photodetectors) have been fabricated. The responsivity peaks blue-shift from 380 to 370 nm (380 to 375 nm) by increasing the bias voltage in 1.0 h (1.5 h) photodetectors, which is denoted by the growth time of one layer of the films. More interestingly, the Au/MgZnO/ZnO/SiO2 photodetectors shift the same response wavelength range at smaller bias voltages than the Au/ZnO/MgZnO/SiO2 photodetectors. The results are well-rationalized in term of the role played by the double-layer structure.