Ultraviolet band-pass Schottky barrier photodetectors formed by Al-doped ZnO contacts to n-GaN

This work prepared Al-doped ZnO(AZO) films using dc sputtering to form Schottky contacts onto GaN films with low-temperature-grown GaN cap layer. Application of ultraviolet photodetector showed that spectral responsivity exhibits a narrow bandpass characteristic ranging from 345to375nm. Moreover, unbiased peak responsivity was estimated to be around 0.12A∕W at 365nm, which corresponds to a quantum efficiency of around 40%. In our study, relatively low responsivity can be explained by the marked absorption of the AZO contact layer. When the reverse biases were below 5V, the study revealed that dark currents were well below 5×10−12A even though the samples were annealed at increased temperatures.