HTRB Stress Effects on Static and Dynamic Characteristics of 0.15 μm AlGaN/GaN HEMTs

High-temperature reverse bias (HTRB) stress effects on static and dynamic characteristics of 0.15
$\mu \text{m}$
AlGaN/GaN high-electron mobility transistors (HEMTs) are reported. The HEMTs were stressed to OFF-state bias (
$V_{\mathrm {GS}} \,\,=\,\,-7$
V and
$V_{\mathrm {DS}} \,\,=$
30 V) at a high temperature of 175 °C for 1000 h of duration. The HTRB-induced changes in drain current (
$I_{\mathrm {DS}}$
) are analyzed. The
$I_{G} - V_{G}$
characteristics are evaluated at
$V_{\mathrm {DS}} \,\,=$
0 V (emulating gate Schottky diode leakage) before and after the stress to examine the Schottky gate diode properties upon aging. The gate leakage current variations are further inspected with
$V_{G}$
and
$V_{D}$
sweeps. After aging test, a considerable drift in the output power (
$P_{\mathrm {out}}$
) is observed during the interim RF measurement of the stressed HEMTs. The pulsed
$I_{\mathrm {DS}} - V_{\mathrm {DS}}$
characteristics reveal the reduction in
$I_{\mathrm {DS}}$
, particularly in the transition between linear and saturation regions; which is referred as knee-voltage smoothing. The output-admittance (
$Y_{22}$
) and drain current transient (DCT) measurements are conducted to track any new defects created in the stressed HEMT and also assess the evolution of the pre-existing trap parameters. Especially, the physical location of the traps responsible for the knee-voltage smoothing and output power drift is identified by TCAD simulations.