Post-gate process annealing effects of recessed AlGaN/GaN HEMTs

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 400C in a nitrogen ambient for l0min 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. ©2008 Chinese Institute of Electronics.