Investigating the Impact of Gate Metals on the Electrical Properties of AlGaN/GaN HEMTs

In GaN-HEMTs, the choice of gate metal plays a significant role in defining electrical properties like threshold voltage, gate breakdown voltage, and output current. This work investigates the effect of different gate metals on electrical parameters in AlGaN/GaN HEMT. The AlGaN/GaN HEMT utilizing various gate metal work functions- Cu, Ni, and Pt are simulated in the Silvaco TCAD ATLAS Tool. Compared to Ni and Cu gates, the Pt gate shows a low value of drain saturation current, high threshold voltage, and breakdown voltage. The simulation result shows a trade-off between threshold voltage and drain current. A positive shift in threshold voltage and sizeable current collapse due to high gate metal work function depicts the reduced charge concentration in 2DEG. The increased Schottky barrier height (SBH) is responsible for reduced 2DEG concentration.