ITON Schottky contacts for GaN based UV photodetectors

Lateral Schottky ultraviolet detectors were fabricated in GaN using indium-tin-oxynitride (ITON) as a contact metal. The GaN semiconductor material was grown on 2 in. sapphire substrate by metal–organic chemical vapor deposition (MOCVD). The Schottky contact has been realized using ITON that has been deposited using sputter techniques. I–V characteristics have been measured with and without UV illumination. The device shows photo-to-dark current ratios of 103 at -1 V bias. The spectral responsivity of the UV detectors has been determined. The high spectral responsivity of more than 30 A/W at 240 nm is explained by a high internal gain caused by generation–recombination centers at the ITON/GaN interface. Persistent photocurrent effect has been observed in UV light (on–off) switching operation, time constant and electron capture coefficient of the transition has been determined.