Enhancing responsivity of porous GaN metal-semiconductor-metal ultraviolet photodiodes by using photoelectrochemical etching

Abstract

In this paper porous and as-grown GaN metal-semiconductor-metal photodiodes with Ni contact electrodes were fabricated. Structural and optical properties were studied of the both samples. Both detectors show a sharp cut-off wavelength at 370 nm, with a maximum responsivity of 0.14 A/W and 0.065 A/W achieved at 360 nm for porous GaN and as-grown metal-semiconductor-metal photodetectors, respectively. The metal-semiconductormetal photodiode based on porous GaN shows enhanced twice magnitude of responsivity relative to the as-grown GaN metal-semiconductor-metal photodiode. Enhancement of responsivity can be attributed to the relaxation of stress and reduction of surface pit density in the porous sample. The porous sample showed a significantly low dark current at 5 V as compared to as grown sample.