Structural and photodetector characteristics of Zn and Al incorporated ZnGa2O4 films via co-sputtering

Abstract

Zn and Al-incorporated ZnGa2O4 films (ZGO:Zn and ZGO:Al) were deposited on sapphire substrates using radio-frequency magnetron sputtering in this work. The effects of Zn and Al incorporation on the microstructural and optoelectronic properties of ZGO films were systematically investigated and compared with each other. This investigation revealed that incorporation of Al enhanced the characteristics of the ZGO film, whereas incorporation of Zn affected the characteristics of the ZGO film. The annealed ZGO:Al film revealed high crystallinity, average transmittance of >82%, and wide-bandgap of 5.18 eV. First principles calculations were performed to investigate the defects associated with the ZGO:Al structure. The Al incorporated ZGO PD exhibited an optimum metal–semiconductor–metal photodetector achievement with a photo/dark current ratio of ∼104 order and responsivity of 3.01 A/W (at 3 V and 220 nm), demonstrating the responsivity of ZGO PD (0.25 A/W) can be increased up to 12 times by incorporating Al in ZGO films. This enhancement in the characteristics of the ZGO:Al film can be ascribed to the high crystalline nature and the formation of significant amount of oxygen vacancies in this film. These results demonstrate the potential of Al incorporated ZGO films in wide-bandgap devices and deep-ultraviolet applications.