Drain-Bias-Dependent Study of Reverse Gate-Leakage Current in AlGaN/GaN HFETs

Reverse gate-leakage of the AlGaN/GaN heterostructure field-effect transistors (HFETs) is studied at different values of drain-source voltage (V-DS), ranging from 0 to 10 V. Throughout the investigated range of V-DS, the reported analysis confirms the applicability of the Fowler-Nordheim (FN) tunneling as the dominant contributor to the gate-leakagefor reverse gate biases until the onset of the threshold voltage. Device simulations were performed using Comsol Multiphysics to estimate the electric field (E) across the polar III-nitride barrier layer at different positions along the gate length. We observe that the FN tunneling takes place predominantly corresponding to the average electric field observed to be close to E at the center of the gate for lower values of V-DS, whereas at larger values of V-DS, FN tunneling corresponding to E only at the drain edge of the gate seems poised to deliver the gate-leakage current. In formulating the FN tunneling, the value of the electron effective mass is selected consistently within an acceptable range for analyzing gate-leakage. Investigating the applicability of FN tunneling in explaining the reverse gate-leakagecurrent of AlGaN/GaN HFETs for the aforementioned values of gate to source voltage (V-GS) not just at zero V-DS, but across a range of V-DS values, seems to offer a more convincing argument for the hypothesis on tunneling through small leakage zones.

Automated summary

The study investigates the reverse gate-leakage of AlGaN/GaN HFETs at different drain-source voltages, revealing that Fowler-Nordheim tunneling contributes to leakage predominantly at the gate center for lower drain-source voltages, while at higher drain-source voltages, leakage occurs mainly at the drain edge. The electron effective mass is consistently chosen within an acceptable range for analyzing gate-leakage.