Influence of High-k Dielectric Materials on AlGaN/AlInGaN/GaN MOS-HEMT Grown on β-Ga2O3Substrate: Numerical Study

In this work, we have analyzed the influence of high-k dielectric materials including silicon nitride
$(\text{Si}_{3}\mathrm{N}_{4})$
, aluminum oxide
$(\text{Al}_{2}\mathrm{O}_{3})$
, hafnium oxide
$(\text{HfO}_{2})$
, and titanium dioxide
$(\text{TiO}_{2})$
on the operational characteristics of T-gate AlGaN/AlInGaN/GaN MOSHEMT on
$\beta-\text{Ga}_{2}\mathrm{O}_{3}$
substrate. The proposed MOSHEMT device structure with T- gate length of 50nm, 5 nm oxide thickness, and quaternary AlInGaN spacer layer was modeled in a
$2\mathrm{D}$
numerical simulation of the commercial Atlas-Silvaco tool. Maximum drain current
$(\mathrm{I}_{\mathrm{d},\max})$
, threshold voltage
$(\mathrm{V}_{\text{th}})$
, maximum transconductance
$(\mathrm{g}_{\mathrm{m},\max})$
, intrinsic capacitances (C
GS
and C
GD
), cut-off frequency
$(\mathrm{f}_{\mathrm{t}})$
, and maximum oscillation frequency were investigated. The analysis showed that the device's frequency performance is improved with high-k dielectric layers and the use of
$\beta-\text{Ga}_{2} \mathrm{O}_{3}$
substrate. The
$\text{HfO}_{2}$
oxide-based MOSHEMT shows excellent characteristics for both the high output current of 3A/mm with low knee voltage and the highest frequency performance of 1216/1770 GHz for ft/frnax, also its threshold voltage is close to the positive value. This analysis allowed the performance characteristics of different oxide layer materials to be observed and will be useful for the selection of suitable dielectric materials for future GaN-based HEMT applications.