Estimation of Zero-Field Activation Energy for Traps in Fe- and C-Doped GaN-Based HEMTs

Carrier emission rate accelerates from a trap with the increase in drain voltage due to the self-heating (SH) and Poole–Frenkel (PF) emission effects; thus, the conventional Arrhenius analysis underestimates the trap activation energy. For this purpose, this work estimates the zero-field (actual) activation energy of a trap in InAlN/GaN and AlN/GaN high-electron mobility transistors (HEMTs) by including SH and PF effects in the emission rate equation. The HEMT thermal resistance (
${R}_{\text {TH}}$
) is computed from the technology computer aided design (TCAD) simulation results. Subsequently, the SH-induced increase in the channel temperature (
${\Delta }{T}$
) is incorporated in the Arrhenius plot, constructed from drain current transient (DCT) and output-admittance (
${Y}_{{22}}$
) parameters. The apparent trap activation energy (
${E}_{\text {ap}}$
) is calculated from the measured DCT and
${Y}_{{22}}$
at different drain voltages, and the respective electric field (
${F}$
) at each bias condition is extracted from the simulation. Finally, zero-field activation energy (
${E}_{{0}}$
) is estimated from the
${E}_{\text {ap}}$
versus (
${F}$
)
$^{{0.5}}$
plot intercept.
${E}_{{0}}$
for the well-known Fe-related buffer trap is identified at
${E}_{C}- {0.7}$
eV in the InAlN/GaN HEMT. Similarly,
${E}_{{0}}$
at
${E}_{C}- {0.51}$
eV is found for the trap in the C-doped AlN/GaN HEMT.