Abstract: This paper focuses on how to reduce the gate leakage current caused by plasma dry etching.X-ray photoelectron spectroscopy (XPS) is employed to measure the AlGaN surface before and after etching.N vacancies are introduced,which cause that gate currents are not dominated by the thermal electron emission mechanism.N vacancies enhance the tunneling effect and reduce the Schottky barrier height as n-type doped in the etched AlGaN surface.A post-gate process for AlGaN/GaN HEMTs,annealing at 400℃ in a nitrogen ambient for 10min is introduced.After annealing,Ni atoms of gate metal reacted with Ga atoms of AlGaN,and N vacancies were reduced.The reverse leakage decreased by three orders of magnitude,the forward turn-on voltage increased and the ideality factor reduced from 3.07 to 2.08.

Key words: GaN, dry etching, gate leakage, annealing, N vacancy