Effect of the post-gate annealing on the gate reliability of AlGaN/GaN HEMTs

In this paper,we investigated the effect of post-gate annealing(PGA)on reverse gate leakage and the reverse bias reliability of Al_(0.23)Ga_(0.77)N/GaN high electron mobility transistors(HEMTs).We found that the Poole-Frenkel(PF)emission is dominant in the reverse gate leakage current at the low reverse bias region(V_(th)<V_(G)<0 V)for the unannealed and annealed HEMTs.The emission barrier height of HEMT is increased from 0.139 to 0.256 eV after the PGA process,which results in a reduction of the reverse leakage current by more than one order.Besides,the reverse step stress was conducted to study the gate reliability of both HEMTs.After the stress,the unannealed HEMT shows a higher reverse leakage current due to the permanent damage of the Schottky gate.In contrast,the annealed HEMT shows a little change in reverse leakage current.This indicates that the PGA can reduce the reverse gate leakage and improve the gate reliability.