Tri-Gate GaN Junction HEMTs: Physics and Performance Space

Abstract

We present the physics and performance space of the tri-gate GaN junction high electron mobility transistor (Tri-JHEMT), a new tri-gate GaN device proposed recently. In Tri-JHEMTs, p-n junctions wrap around two-dimensional-electron-gas (2DEG) fins in the gate region. Our fabricated Tri-JHEMT demonstrates, for the first time, the kilovolt blocking capability at 150 °C in all tri-gate GaN high electron mobility transistors (HEMTs). Three-dimensional TCAD simulations were then calibrated with experimental devices and used to study p-GaN-based Tri-JHEMTs with various design parameters for a direct comparison with the industrial planar p-gate GaN HEMTs. Owing to the unique physics of the sidewall p-GaN/2DEG junction, the 2DEG distribution in junction tri-gates is very different from that in conventional tri-gates, enabling smaller gate capacitance and superior gate controllability. As a result, a lower resistance in the gated channel, a higher wafer 2DEG density, and a scaled gate length can be concurrently realized in normally-OFF Tri-JHEMTs. GaN Tri-JHEMTs designed for a wide range of voltage classes (15-1200 V) are predicted to enable a 15%-75% lower ON-resistance (RON), 3-10-fold smaller RON QG (gate charge), and 45%-63% smaller RON QOSS (output charge) as compared with similarly rated planar p-gate HEMTs. Considering their fabrication compatibility with existing foundry process, Tri-JHEMTs show great potentials as the next-generation lateral GaN power switches.