Impact of 2D-Graphene on SiN Passivated AlGaN/GaN MIS-HEMTs under Mist Exposure

The effect of a two dimensional (2D) graphene layer (GL) on top of the silicon nitride (SiN) passivation layer of AlGaN/GaN metal-insulator-semiconductor high-electron-mobility transistors (MIS-HEMTs) has been systematically analyzed. Results showed that in the devices without the GL, the maximum drain current density (I_D,max) and the maximum transconductance (g_m,max) decreased gradually as the mist exposure time increased, up to 23% and 10%, respectively. Moreover, the gate lag ratio (GLR) increased around 10% during mist exposure. In contrast, devices with a GL showed a robust behavior and not significant changes in the electrical characteristics in both DC and pulsed conditions. The origin of these behaviors has been discussed and the results pointed to the GL as the key factor for improving the moisture resistance of the SiN passivation layer.