Suppression of Buffer Trapping Effect in GaN-on-Si Active-Passivation p-GaN Gate HEMT via Light/Hole Pumping
Yanlin Wu, Muqin Nuo, Junjie Yang, Wei Lin, Xiaosen Liu, Xuelin Yang, Jinyan Wang, Yilong Hao, Bo Shen, Maojun Wang, Jin Wei
Abstract
This work investigates the effect of hole injection/light emission to suppress buffer-related dynamic <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <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 xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${R}_{\text {ON}}$ </tex-math></inline-formula> . In the positive substrate voltage ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${V}_{\text {SUB}}{)}$ </tex-math></inline-formula> sweep test, the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <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 xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${I}_{\text {D}}$ </tex-math></inline-formula> during VSUB back-sweeps. In the recovery test after a <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${V}_{\text {SUB stress}}$ </tex-math></inline-formula> , the AP-HEMT experiences much smaller initial <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <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 xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${R}_{\text {ON}}$ </tex-math></inline-formula> degradation.