  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.
