Surface HCl treatment in ZnO photoconductive sensors

In this paper, we report the effect of surface HCl treatment on ZnO photoconductive sensors with Ni/Au electrodes after the etching process. Epitaxial ZnO photoconductive sensor film on sapphire substrates was fabricated and then treated with different HCl concentrations. With an incident light wavelength of 370 nm and an applied bias of 10 V, the responsivity of the sensor measured is around 141 mA/W after being treated with 0.7% HCl solution. The result indicates that the a larger surface available for photodetection could be realized by increasing the surface roughness of the ZnO photoconductive sensor. It was also found that the low-frequency and high-frequency noises of the fabricated sensors were dominated by 1/f-type and shot noises, respectively.