Hybrid p-GaN/MIS Gate HEMT Suppressing Drain-Induced Dynamic Threshold Voltage Instability

This letter demonstrates a hybrid p-GaN/MIS gate HEMT (HG-HEMT) to suppress the drain-induced dynamic threshold voltage (<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${V}_{\text {th}}\text {)}$ </tex-math></inline-formula> instability. By implementing a depletion-mode (D-mode) MIS gate adjacent to Schottky-type p-GaN gate, the drain-induced bidirectional shift of dynamic <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${V}_{\text {th}}$ </tex-math></inline-formula> is significantly reduced. The fabricated HG-HEMT exhibits decent performances compared to the conventional Schottky-type p-GaN gate HEMT (Conv-HEMT), with saturation current (<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${I}_{\text {D, {sat}}}\text {)}$ </tex-math></inline-formula> of 345 mA/mm, on-resistance (<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${R}_{\text {ON}}\text {)}$ </tex-math></inline-formula> of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$13.2~\Omega \cdot $ </tex-math></inline-formula> mm, and hard breakdown voltage (<italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">BV</i>) of 1315 V, which are similar to the Conv-HEMT. The HG-HEMT demonstrates significantly improved dynamic <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${V}_{\text {th}}$ </tex-math></inline-formula> stability under drain bias, with a negligible dynamic <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${V}_{\text {th}}$ </tex-math></inline-formula> shift at on-state drain bias of 50 V, and a small positive dynamic <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${V}_{\text {th}}$ </tex-math></inline-formula> shift of +0.05 V after off-state drain bias of 400 V. As a comparison, <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${V}_{\text {th}}$ </tex-math></inline-formula> shifts of the Conv-HEMT are −0.28 V and +0.42 V, respectively. The improved dynamic <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${V}_{\text {th}}$ </tex-math></inline-formula> stability of the HG-HEMT is owing to a D-mode MIS-gate region that shields the interplay between drain and the p-GaN region. The proposed HG-HEMT paves the way for highly stable GaN power electronics applications.