Suppression of back-gating effects in GaN-on-Si p-GaN gate double-channel HEMT by enhanced storage and spreading of photon-generated holes

This work demonstrates effective suppression of back-gating effects in Schottky-type p-GaN gate double-channel high-electron-mobility transistors (DC-HEMTs) under ultraviolet (UV) illumination, offering a promising pathway for monolithic integration of half-bridge circuits. When the DC-HEMTs are subjected to UV illumination, electron–hole pairs (EHPs) are generated in the access regions by incident photons from an external 340-nm UV light-emitting diode and subsequently separated by the vertical electric field induced by either a negative substrate bias (VSUB) or buffer electron trapping. The photon-generated electrons migrate toward the two-dimensional electron gas (2DEG) channels, thereby restoring the 2DEG in the access regions. Critically, a dedicated hole-spreading channel is formed between the closely coupled 2DEG channels, enabling efficient storage and transport of photon-generated holes. Those holes generated in the upper channel are partially blocked by the thin AlN insertion layer (AlN-ISL) and then spread along the intermediate channel toward the gated region that is not exposed to UV light. The resulting hole storage beneath the entire active channel provides effective screening to the upper channel and induces electrons in the lower channel to compensate back-gating effects. The hole-spreading dynamics can be described by the drift-diffusion model, which indicates an efficient spreading process. These findings highlight the significant potential of the p-GaN gate DC platform for integrated half-bridge circuits by harnessing the photon-generated carriers to suppress the back-gating effects.