Charge-Modulated Schottky Barrier Lowering Effect in GaN Double-Channel Lateral Power SBDs with Gated Anode

The charge-modulated Schottky barrier lowering (SBL) effect is revealed and studied on an AlGaN/GaN lateral SBD with gated anode. The fabricated SBD features a metal-2DEG Schottky contact and a leakage suppression MIS field plate to provide both low turn-on voltage ( VT) and low reverse leakage current ( IR). It is revealed that the SBDs with higher carrier density in the channel under the MIS field plate (MIS-channel) exhibits lower VT, higher IR and lower Schottky barrier height ( φB, which is extracted from the forward I-V curves based on the thermionic emission model). The φB of the metal-GaN junction can be lowered by the image charge in the metal electrode. A higher carrier density in the MIS-channel yields a narrower Schottky barrier, which benefits a more prominent image force induced SBL effect and leads to a lower φB.