The enhanced sensing performance of ZnO-based photodetector by Mg doping

In this paper, we study the effect of Mg on the structural, optical, and electrical properties of a ZnO-based photodetector. The sample was prepared by making a ZnO seed layer via spray pyrolysis. Then, the Mg-doped ZnO (MZO) nanorod was deposited on the seed layer via a hydrothermal technique with Mg concentrations of 0 wt % (ZnO), 1 wt% (MZ1), 3 wt% (MZ3), and 5 wt% (MZ5). From X-ray diffraction measurement, all samples show a hexagonal wurtzite structure. The nanorod formation of all samples was confirmed by scanning electron microscope images. Higher Mg dopant increases nanorod size from 872 +/- 8 nm (pure ZnO) to 1764 +/- 85 nm (5 % Mg). UV-Vis spectroscopy analysis shows that the bandgap generally increases with increased Mg content. Mg doping increases not only photoconductivity but also UV sensitivity by about 6 (ZnO), 46 (MZ1), 69 (MZ3), and 321 (MZ5). Responsivity increases linearly from 0.13 (ZnO) to 73.34 A/W (MZ5), and detectivity also increases linearly from 8.29 x 108 (ZnO) to 1.56 x 1011 Jones (MZ5). This study is essential to realize photodetector devices with low-cost fabrication techniques.