Deep sub micron normally off AlGaN/GaN MOSFET on silicon with VTH > 5V and On Current > 0.5 A/mm

TL;DR

This paper demonstrates a deep sub-micron normally-off AlGaN/GaN HEMT on silicon with high on-current and threshold voltage, achieved through precise gate recess engineering and dielectric annealing, with insights from device simulations.

Contribution

It introduces a novel fabrication process for high-performance normally-off AlGaN/GaN HEMTs with VTH > 5V and on-current > 0.5 A/mm on silicon substrate.

Findings

Achieved VTH > 5V and on-current > 0.5 A/mm in a sub-micron device.

Optimized device performance through gate recess and dielectric annealing.

Identified breakdown limitations via 2D-TCAD simulations.

Abstract

We report on the demonstration of a deep sub-micron normally-off AlGaN/GaN HEMT with high on-current and high threshold voltage (VTH). The high-performance device was realized by utilizing a gate recess with length and depth of 200 nm and 124 nm respectively. The recess etched region had a roughness of 0.7 nm. Various recess etch depths and dielectric annealing conditions were used to tune the VTH. The optimized device exhibited on-current and VTH of 500 mA/mm and 5 V respectively. The measured breakdown characteristics of the devices and their limitations were investigated using 2D-TCAD device simulation. The penetration of the residual electric field in most of the recess region could be the reason for the premature breakdown of deeply scaled recess-gate e-mode HEMTs.