Study on the Optimization of Off-State Breakdown Performance of p-GaN HEMTs

Normally-off Gallium Nitride (GaN) transistors with p-GaN gated technology for power applications are studied for the optimization of off-state breakdown performance. The gate-drain distance, gate length, field plate length and its configuration have been studied. Increase gate-drain distance will not only enhance the breakdown performance but also increase the
$\mathrm{R}_{\mathrm{on}},\ \mathrm{L}_{\mathrm{GD}}$
between
$10 -20\ \mu\mathrm{m}$
is recommended. Extra gate length will lead to the rising of the gate leakage current under high voltage. The overhang length of the field plate is a critical factor for breakdown performance, over placing the length of overhang may result in an additional current leakage path.