Strain-induced photoresponsivity in gallium-doped ZnO thin film based UV photodetectors

The effect of varying Ga-doping on structural, optical, and UV detection properties of ZnO/p-Si based photodetectors is reported in this paper. Herein, the pure and gallium (Ga) (1 at%, 2 at%, and 3 at%) doped ZnO thin films are deposited on p-Si substrates by the sol–gel spin-coating method. On the basis of characteristic investigations, it is found that the varying Ga-doping affects not only the structural and optical properties of ZnO films, but also their electrical characteristics and hence significantly changes the performance of the devices employing ZnO films. Moreover, it is observed that the band gap size of the films is linearly dependent on strain values. As for the photodetector performance, it is found that the photodetector with 2 at% Ga doped ZnO demonstrates an excellent device performance, yielding a RR of 7908, PDCR of 171.7, PR of 8.15 (A/W) with D* of 5.4 × 1012 Jones, EQE of 2769.5%, and G of 27.69. The results suggest that the resulting device has a high potential for UV sensor applications.