Nonalloyed ohmic formation for p-type AlGaN with p-type GaN capping layers using ohmic recessed technique

In this study, we report that the p-type GaN (p-GaN) capping layer grown on top of p-type AlGaN (p-AlGaN) and the fabrication of recessed channels are used to demonstrate a new type of nonalloyed ohmic contact. Because the p-GaN layer grown on p-AlGaN led to the formation of spontaneous polarization fields in p-GaN and the lower band bending of p-AlGaN resulting in the formation of a two-dimensional hole gas (2DHG). As a result, we deduce that holes can be easily injected into the p-AlGaN layer through recessed channels and a 2DHG channel, which results in nonalloyed ohmic formation.