Monolithic Investigation of Hydrogen Plasma-Treated and Etched p-GaN Gate HEMTs Under OFF-State Drain Stress

In power conversion systems, the power devices often need to block high voltage levels during the OFF-state. The impact of such voltage stress can cause instability for the device. This article presents the investigation of the pulsed
${I}$
–
${V}$
(PIV) OFF-state drain stress test for the etch-free hydrogen plasma-treated p-GaN gate HEMT (H-treated devices). To quantitatively demonstrate the effect of the hydrogen plasma treatment process, the device with conventional p-GaN etching at the access region (etched devices) is monolithically fabricated. Remarkably, the hydrogen treatment could eliminate surface damage from the conventional etching process and provide passivation at the access region. The direct comparison of devices’ threshold voltage (
${V} _{\text {TH}}$
) shift and dynamic ON-resistance (
${R} _{\text {on}}$
) is obtained. Under a 200-V OFF-state drain stress, the H-treated device has a low
${V} _{\text {TH}}$
shift of 0.18 V, and the dynamic
${R} _{\text {on}}$
could also be efficiently suppressed by 24%. Meanwhile, the H-treated device has only a marginal 5% current reduction compared with 48% for the etched device at 200-V stress. An exploration of the origin of the superior device performances is carried out with the TCAD simulation, activation energy derivation, and capacitance measurement. For the H-treated device, the surface state improvement at the region and the reduction of the peak electric field at the gate edge become major reasons for the improved performance.