Combination of selective area sublimation of p-GaN and regrowth of AlGaN for the co-integration of enhancement mode and depletion mode high electron mobility transistors

The sublimation of GaN is a powerful alternative etching technique to avoid the electrical traps usually induced by dry etching. It is selective towards Al containing alloys such as AlGaN and towards dielectric materials like silicon oxide or silicon nitride so that patterns can be defined to fabricate devices based on GaN/AlGaN heterostructures. In the present work, we report on the fabrication of enhancement mode p-GaN/Al(Ga)N/GaN high electron mobility transistors (HEMTs) with selective area sublimation under vacuum of the p-GaN cap layer used to define the gate. Furthermore, we show that sublimation can be combined with the regrowth of AlGaN, which is a key to increase the maximum drain current in the transistors and enables the co-integration of enhancement mode devices with depletion mode ones.