GaN MSM photodetectors with photo-CVD annealed Ni/Au electrodes

Thin Ni/Au (3/6 nm) bi-layer metal films annealed by photo-chemical vapor deposition (photo-CVD) were investigated. With proper annealing in oxygen by the photo-CVD systems, it was found that the transmittance of the deposited Ni/Au increased from 67 to 85% in the region between 350 and 450 nm. GaN metal–semiconductor–metal (MSM) ultraviolet (UV) photodetectors with photo-CVD annealed Ni/Au contact electrodes were also fabricated. It was found that dark current of the detector became significantly smaller after annealing. With a 1 V applied bias, it was found that we can achieve a photocurrent to dark current contrast ratio of 2.54×103 from the photodetectors with 600 °C photo-CVD annealed Ni/Au contacts.