Effects of forward gate bias stressing on the leakage current of AlGaN/GaN high electron mobility transistors

Reliability of AlGaN/GaN-on-Si high electron mobility transistors (HEMTs) under forward gate bias was studied. During stressing, devices were observed to degrade through an increase in the gate leakage current. The degradation was correlated with a decrease in the Schottky barrier height. Using photon emission microscopy (PEM), transmission electron microscopy (TEM) and electron energy loss spectroscopy (EELS), the physical cause of the degradation was identified as localized carbon residue at the AlGaN/Ni gate interface.