Ultraviolet band-pass photodetectors formed by Ga-doped ZnO contacts to n-GaN

In this study, Ga-doped ZnO (GZO) films prepared by cosputtering were deposited onto n-GaN films with a low-temperature-grown GaN cap layer to form Schottky barrier photodetectors (PDs). The ultraviolet (UV) PDs exhibited a narrow band-pass spectral response ranging from 340 to 390 nm. The short-wavelength cutoff at around 340 nm can be attributed to the marked absorption of the GZO contact layer. With a zero-biased condition, the UV PDs exhibited a typical peak responsivity of around 0.10 A/W at 365 nm, which corresponds to the quantum efficiency of around 34%. When the reverse biases were below 10 V, the dark currents of the PDs were well below 30 pA. (c) 2008 American Institute of Physics.