GaN metal-semiconductor-metal UV photodetector with recessed electrodes

GaN-based metal-semiconductor-metal photodetectors (MSM-PDs) with a recessed-electrode structure have been fabricated and characterized. The photodiodes exhibited low leakage currents with a typical value of 51 pA at 10 V. Spectral response revealed a responsivity up to 0.14 A/W at 350 nm under 10 V bias, corresponding to an internal quantum efficiency of about 90%, which is a 55.6% improvement over that of conventional MSM-PDs with planar electrodes. The improvement was attributed to the enhanced and uniform electric field due to the recessed electrodes in the photoactive region, leading to a more efficient carrier collection.