LARGE AREA GaN METAL SEMICONDUCTOR METAL (MSM) PHOTODIODE USING A THIN LOW TEMPERATURE GaN CAP LAYER

Abstract

Small area metal semiconductor metal (MSM) photodiode (PD) has been one of the most favoured detector choices for high speed optoelectronics integrated circuits due to their low parasitic capacitance and simple planar device structure, which is compatible with FETs. Large MSM PDs, on the other hand, can also be useful in many network and interconnect applications such as fibre distributed data interfaces. An MBE grown GaN metal semiconductor metal photodiode with a thin low temperature GaN (50nm) barrier enhancement layer is reported, which has low dark current. The detector using Nickel ( Ni ) Schottky metal fingers with 400 μm spacing on a large active area exhibit a low dark current of 1.23 mA at 10 V bias, which is about three orders of magnitude lower than that of the normal GaN Schottky photodiode.