0.9-A/mm, 2.6-V Flash-Like Normally-Off Al2O3/AlGaN/GaN MIS-HEMTs Using Charge Trapping Technique

Flash-like Al
₂
O
₃
/AlGaN/GaN metal–insulator–semiconductor high electron mobility transistors (MIS-HEMTs) were fabricated using a charge trapping technique. These MISHEMTs showed a large threshold voltage (
${V}_{\text {th}}$
) shift of 9.35 V after applying a 10-V program voltage (
${V}_{P}$
), resulting in a normally-off device with a high
${V}_{\text {th}}$
of 2.6 V and a high maximum drain current (
${I}_{\mathrm {dmax}}$
) of 0.9 A/mm. The
${V}_{\text {th}}$
dependence on
${V}_{P}$
was analyzed and
$V_{\text {th}}$
was above 0 V for
${V}_{P} = 8$
V. Photo-assisted
$C$
–
$V$
measurements revealed that the traps contributing to the large
${V}_{\text {th}}$
shift had a density of
$2.18\times 10^{13}$
cm
⁻²
and the activation energy for the photo-assisted de-trapping process ranged from 2.67 to 3.06 eV. These traps were attributed to border or oxide defects. The retention level of the device was up to 10
²
s after applying 10-V
${V}_{P}$
. These results indicate that the charge trapping method with a single Al
₂
O
₃
dielectric is a promising way to achieve normally-off devices with both high
${V}_{\mathrm {th}}$
and high
${I}_{\mathrm {dmax}}$
.