Nitride-based photodetectors with unactivated Mg-doped GaN cap layer

Nitride-based MIS-like photodetectors with in situ grown 30 nm thick unactivated semi-insulating Mg-doped GaN cap layers were fabricated. It was found that the reverse leakage current of aforementioned photodetector was comparably much smaller than that of conventional photodetector without the semi-insulating layer, due to the facts that inserting a semi-insulating layer would result in a thicker and higher potential barrier. We could also improve the ultraviolet to visible rejection ratio by inserting a semi-insulating Mg-doped GaN cap layer. To sum up, we have determined that the benefits of incorporating a semi-insulating Mg-doped GaN cap layer into the photodetector would encompass larger effective Schottky barrier height, and larger ultraviolet to visible rejection ratio. (c) 2007 Elsevier B.V. All rights reserved.