High 366/254-nm Rejection Contrast GaN MIS Photodetectors Using Nano Spin-Oxide

In this paper, GaN-based metal-insulator-semiconductor (MIS) photodetectors (PDs) with liquid-phase deposition oxide (LPD oxide) or nanospin oxide were fabricated and compared. Compared to the MIS-PDs with LPD oxide, the nanospin-oxide device can dramatically reduce the optical response of 254 nm by two orders while still retaining the same 366-nm optical response as LPD oxide. The 366/254-nm rejection contrast is raised from 5.13 to 413 for the MIS-PDs with LPD and spin oxides, respectively. Thus, one can simply insert a thin (10 nm) nanospin-oxide layer between the metal and GaN to significantly reduce the response of 254 nm. Possible mechanism is discussed here.