GaN -based electronic devices—such as Schottky barrier diodes, pin diodes, and AlGaN/GaN HEMTs—have demonstrated superior figures of merit (FOMs) compared with Si-based electronics for power-switching-circuit applications. For example, in the Baliga FOM (BV²/R_ON), where BV is the breakdown voltage and R_ON is the on-state resistance, GaN-based power devices have lower R_ON at the same BV, reducing conduction loss and increasing efficiency. In the switching FOM (R_ON × Q_G), where Q_G is the gate charge, GaN-based devices demonstrate much lower Q_G at the same R_ON, further lessening the switching loss at higher frequencies. These effects are explained by the higher mobility of electrons in the 2DEG and the electric field breakdown of GaN-based materials as opposed to that in Si materials. However, to continue replacing Si power electronics, enhancement-mode (E-mode) operation of AlGaN/GaN HEMTs is required. Approaches to implementing E-mode operation have included a p-GaN gate, recess MIS gate, F-doped gate, and cascode configurations. As for the p-GaN gate HEMT, this technology is more popular in commercial products with controllable V_TH. However, challenges remain for this p-GaN gate structure, including low gate swing range, high gate leakage, and high gate reliability from Mg-doped GaN. A large V_TH is required to prevent power switches from faulty turn-on by EMI, noise, and a large slew rate of drain voltage (dV/dt). In this talk, methods to improve the V_TH in the E-mode p-GaN gate AlGaN/GaN HEMTs are presented.