Enhancement-Mode Multi-Channel AlGaN/GaN Transistors With LiNiO Junction Tri-Gate
Taifang Wang, Yuan Zong, Luca Nela, Elison Matioli
Abstract
Multi-channel GaN power device, consisting of stacking multiple two-dimensional-electron-gas (2DEG) channels, has been demonstrated to achieve unprecedented on-state performance while maintaining high breakdown voltage ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${V}_{BR}$ </tex-math></inline-formula> ). However, the large carrier density ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${N}_{s}$ </tex-math></inline-formula> ) makes it more challenging to achieve high positive threshold voltages ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${V}_{TH}$ </tex-math></inline-formula> ) on multi-channel epitaxies. In this work, we demonstrate enhancement-mode (e-mode) multi-channel GaN transistors based on conformally deposited p-type LiNiO over tri-gates to form a multi-channel junction gate structure. Compared to the normal MOS gate, the p-type LiNiO junction gate provides an additional depletion of the channels to yield a more positive <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${V}_{TH}$ </tex-math></inline-formula> , reaching a maximum <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${V}_{TH}$ </tex-math></inline-formula> of 1.2 V (defined at <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$1 ~\mu \text{A}$ </tex-math></inline-formula> /mm). Moreover, high-quality LiNiO provided excellent on-state performance in multi-channel tri-gate devices with a stable operation at high temperature, which present small <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${V}_{TH}$ </tex-math></inline-formula> shift and hysteresis, and low off-state leakage current. The e-mode devices in this work presented a small specific <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${R}_{ON}$ </tex-math></inline-formula> ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${R}_{ON, sp}$ </tex-math></inline-formula> ) of 0.62 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{m}\Omega \cdot $ </tex-math></inline-formula> cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−2</sup> along with a hard breakdown voltage ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${V}_{BR}$ </tex-math></inline-formula> ) of 920 V. This work demonstrates the potential of LiNiO for high-performance e-mode power devices.