Nitride-based MIS-like photodiodes with semiinsulating Mg-doped GaN cap layers

Nitride-based metal-insulator-semiconductor (MIS)-like photodiodes (PDs) with in situ grown 30-nm-thick unactivated semiinsulating Mg-doped GaN cap layers were fabricated. The authors found that the reverse leakage current of the aforementioned PD was comparably much smaller than that of conventional PD without the semiinsulating layer due to the facts that inserting a semiinsulating layer would result in a thicker and higher potential barrier, and also less amounts of interface states introduced. To sum up, it was determined that the benefits of incorporating a semiinsulating Mg-doped cap layer into the PD would encompass a larger photocurrent-to-dark-current contrast ratio and larger ultraviolet-to-visible rejection ratio.