Design and Simulation of High Performance Lattice Matched Double Barrier Normally Off AlInGaN/GaN HEMTs

A novel lattice matched double barrier Al
_0.72
In
_0.16
Ga
_0.12
N/Al
_0.18
In
_0.04
Ga
_0.78
N/GaN normally-off high electron mobility transistor (HEMT) is designed and simulated by solving a set of thermodynamic transport equations. Using the experimentally calibrated physical models with bearing mobility degradation by surface roughness in account, the recess gate and double barrier of the proposed device achieves a maximum drain current density (
$I_{D,max}$
) of 1149 mA/mm and a maximum transconductance (
$g_{m,max}$
) of 358 mS/mm with a positive threshold voltage (
$V_{th}$
) of 0.2 V. The small polarization charge of first barrier is responsible for positive
$V_{th}$
.
$I_{DS,max}$
in the double barrier HEMT at high gate bias condition is due to injection of electrons from upper 2DEG which is almost impossible at lower gate voltage because of insufficient energy to cross the barrier. The injection of electrons is further supported by the second peak in the
$\text{g}_{m}$
curve at low gate bias
$V_{G} = 1\text{V}$
. The outcome of this study suggests that the proposed device will be beneficial for high-frequency and high-power electronic applications.