A Gate Sinking Threshold Voltage Adjustment Technique for High Voltage GaN HEMT.

摘要

GaN-based power electronics receive many interests because of its wider bandgap, higher electron mobility and higher critical electrical field than silicon. However, the intrinsic AlGaN/GaN-based HEMT is a "normally-on" device. This thesis proposes a gate sinking method during the metal gate deposition to adjust the VT towards enhancement mode operation. This recessed gate process relies on the chemical reaction between Ta and AlGaN using a simple RTA procedure rather than the more complicated RIE method. This eliminates the need for etching with nanometer precision. During the Ta sputtering process, both Ar and N2 carrier gases are used to form TaN with work function in the range of 4.15 to 4.7 eV. The fabricated HV GaN HEMTs exhibit VT shift from -5 to -2 V. Moreover, the proposed device is compatible with silicon-CMOS technology to ensure cost-effective implementation of future high performance smart power ICs.