Breakdown voltage enhancement in lateral AlGaN/GaN heterojunction FETs with multiple field plates

It has been proposed in the literature to use metal field plates (FPs) in order to increase the breakdown voltage (BV) of AlGaN/GaN HEMTs. In this article we analyze the possibility of using multiple FPs to increase the gate-to-drain BV. We show that FPs with variable oxide thickness (with thinner oxide towards the gate electrode and thicker oxide thickness towards the drain electrode) increase the BV more efficiently than a single FP. FPs with variable oxide thickness can be built using multiple FPs with increasing oxide thickness from gate to drain and, when all FPs are connected to the source electrode.