Enhancement-mode Multi-channel AlGaN/GaN Transistors with LiNiO Junction Tri-Gate

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 (VBR). However, the large carrier density (Ns) makes it more challenging to achieve high positive threshold voltages (VTH) 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 VTH, reaching a maximum VTH of 1.2 V (defined at 1 μA/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 VTH shift and hysteresis, and low off-state leakage current. The e-mode devices in this work presented a small specific RON (RON, sp) of 0.62 mΩ∙cm-2 along with a hard breakdown voltage (VBR) of 920 V. This work demonstrates the potential of LiNiO for high-performance e-mode power devices.