Monolithic E/D-mode P-GaN/AlGaN/GaN HFETs using reactivation annealing process

A reactivation annealing process was developed to restore the deactivated p-type characteristics of an Mg-doped p-type GaN layer subsequent to exposure to the SiNx passivation step in a p-GaN gated AlGaN/GaN heterojunction field-effect transistor (HFET). The deactivation, induced by the formation of H–Mg complexes during the passivation process, necessitates an additional activation annealing procedure. Notably, it was observed that the passivation film on the p-GaN layer must be removed through etching prior to annealing, aiming to eliminate H atoms from H–Mg complexes. The reactivation annealing process was conducted at 800 °C. Employing this reactivation approach, we successfully demonstrated monolithic enhancement- and depletion-mode p-GaN/AlGaN/GaN HFETs.