Suppression of Buffer Trapping Effect in GaN-on-Si Active-Passivation p-GaN Gate HEMT via Light/Hole Pumping

This work investigates the effect of hole injection/light emission to suppress buffer-related dynamic <inline-formula> <tex-math notation="LaTeX">${R}_{\text {ON}}$ </tex-math></inline-formula> degradation in an E-mode GaN-on-Si active-passivation p-GaN gate high electron mobility transistor (AP-HEMT). The AP-HEMT features a thin p-GaN layer (i.e., the active passivation) covering the drain-side access region. The conventional p-GaN gate HEMT (Conv-HEMT) has been reported to mitigate the buffer trapping by hole injection/light emission from gate that pumps out the trapped electrons in buffer. In the AP-HEMT, hole injection and light emission occurs at the active passivation region as well. To evaluate the effectiveness of the hole/light pumping effect in AP-HEMT, back-gating measurements were performed to assess the recovery of buffer-related dynamic <inline-formula> <tex-math notation="LaTeX">${R}_{\text {ON}}$ </tex-math></inline-formula>. In the positive substrate voltage (<inline-formula> <tex-math notation="LaTeX">${V}_{\text {SUB}}{)}$ </tex-math></inline-formula> sweep test, the <inline-formula> <tex-math notation="LaTeX">${I}_{\text {D}}$ </tex-math></inline-formula> of Conv-HEMTs drops significantly during the back-sweep due to the negative charges trapped in the buffer. However, the AP-HEMT shows no reduction in <inline-formula> <tex-math notation="LaTeX">${I}_{\text {D}}$ </tex-math></inline-formula> during VSUB back-sweeps. In the recovery test after a <inline-formula> <tex-math notation="LaTeX">${V}_{\text {SUB stress}}$ </tex-math></inline-formula>, the AP-HEMT experiences much smaller initial <inline-formula> <tex-math notation="LaTeX">${I}_{\text {D}}$ </tex-math></inline-formula> degradation and recovers much faster than the Conv-HEMT. These results confirm that the hole/light pumping effect in the AP-HEMT effectively suppresses buffer-related dynamic <inline-formula> <tex-math notation="LaTeX">${R}_{\text {ON}}$ </tex-math></inline-formula> degradation.