GaN-Based Metal-Insulator-Semiconductor Ultraviolet Photodetectors with CsF Current-Suppressing Layer

GaN metal-insulator-semiconductor (MIS) ultraviolet (UV) photodetectors (PDs) with the CsF current-suppressing layer were, for the first time, fabricated and characterized successfully. It was found that we can achieve a low dark current and large photocurrent-to-dark-current contrast ratio from the proposed devices with the use of the CsF current-suppressing layer. With a 5 V applied bias, it was found that the leakage current of the fabricated MIS PDs with the CsF current-suppressing layer was 7.1 x 10(-10) A. This small leakage current should be attributed to the large barrier height caused by the insertion of the CsF current-suppressing layer. With a 5 V applied bias, the barrier height of Phi(B) = 0.942 can be calculated from the dark current-voltage (I-V) characteristics. We can also achieve a large UV-to-visible rejection ratio from the PDs with the CsF current-suppressing layer. (C) 2012 The Japan Society of Applied Physics