Enhanced performance of ultraviolet photodetector based on sputtered ZnO/Au/ZnO multilayer structure

This work presents the optimization, elaboration and characterization of a new MSM UV photodetector (PD) design based on an amended active region with ZnO/Au/ZnO (ZAZ) hetero-structure. An experimental investigation assisted by Genetic Algorithm (GA) global optimization was conducted for engineering the proposed ZAZ multilayer in order to achieve high-responsivity UV sensor. The RF magnetron sputtering technique was then used to elaborate the optimized tri-layered structure yielding the highest photoresponse. The structural and optical properties of the sputtered multilayer design were also investigated via X-ray diffraction (XRD) and UV-Vis absorbance measurements. Interestingly, electrical characterizations show that the optimized design is beneficial in two ways, firstly an ultrahigh responsivity of 1.3A/W was successfully demonstrated and secondly, the dark current was greatly reduced in comparison with that of the conventional design. This is attributed to the global optimization approach, enabling exciting opportunities for promoting strong light-matter interactions by improving the light trapping capability and photocurrent generation. Moreover, the inserted Au layer induces the band bending gradient benefit, leading to an efficient transfer of the photogenerated carrier and hinders the recombination effects, which paves a new path toward fabricating high-responsivity UV PDs based on low-cost ZnO earth abundant material.