High-detectivity GaN MSM photodetectors with low-temperature GaN cap layers and Ir/Pt contact electrodes

GaN-based metal-semiconductor-metal (MSM) UV photodetectors (PDs) with a low-temperature (LT) GaN cap layer and Ir/Pt contact electrodes were fabricated. Compared with the conventional Ni/Au contacts, we found that Ir/Pt contacts can reduce the dark current. Further, a smaller dark current and larger UV-to-visible rejection ratio obtained from the PD with LT GaN cap layer and Ir/Pt contact electrodes were determined. Furthermore, the noise equivalent power and detectivity (D*) were respectively obtained as 2.75 x 10(-13) W and 1.76 x 10(12) cm Hz(0.5) W-1 for the aforementioned PDs. (c) 2007 The Electrochemical Society.