High Drain Current Density E-Mode ${\rm Al}_{2}{\rm O}_{3}$/AlGaN/GaN MOS-HEMT on Si With Enhanced Power Device Figure-of-Merit $(4\times 10^{8}~{\rm V}^{2}\Omega^{-1}{\rm cm}^{-2})$

In this paper, we report on the enhancement-mode (E-mode) Al
₂
O
₃
/AlGaN/GaN metal-oxide-semiconductor high-electron mobility transistors (MOS-HEMTs) on Si. The E-mode operation is due to the negative charges in the atomic layer deposited Al
₂
O
₃
layer. The unrecessed E-mode MOS-HEMTs exhibit high drain current density with a low specific ON-state resistance (R
_ON
,
_sp
) of 0.7 mΩ·cm
²
. A low gate leakage current showed enhancements in the subthreshold characteristics such as ION/IOFF ratio ~10
⁸
and subthreshold slope of 75 mV/decade. This E-mode device showed good retention characteristics of threshold voltage upto 10
⁵
s. Furthermore, the E-mode MOS-HEMT exhibits an OFF-state breakdown voltage of 532 V for short gate-to-drain distance (L
_gd
=4 μm) that records a high power device figure of merit (FOM=BV
²
/R
_ON,sp
) value of 4×10
⁸
V
²
Ω
^-1
cm
^-2
.