Correlation Between DC–RF Dispersion and Gate Leakage in Deeply Recessed GaN/AlGaN/GaN HEMTs

摘要

Employing deeply recessed GaN/AlGaN/GaN high-electron mobility transistors, we experimentally demonstrate the correlation between the dc–RF dispersion and the gate leakage current. It was found that both the dc–RF dispersion and the gate leakage are strongly affected by surface charging. The impact of surface charging can be controlled by using GaN/AlGaN/GaN structures with varied GaN cap thickness. In the absence of field plates, the tradeoff between the dc–RF dispersion and the gate leakage can be compromised by choosing a proper GaN cap thickness. Our optimum epistructure design yields an output power density of 5.6 W/mm with an associated power added efficiency of 72% at 28-V bias and 4-GHz frequency. The gate leakage current is as low as 30 $muhbox{A/mm}$ at up to 40-V gate–drain bias.