Field-plate structure dependence of current collapse phenomena in high-voltage GaN-HEMTs

Four types of the field-plate (FP) structure were fabricated to discuss the relation between the current collapse phenomena and the electric-field peak in high-voltage GaN-HEMTs. The on-resistance increase caused by current collapse phenomena is dramatically reduced by the single-gate-FP and dual-FP structures compared with the sourceFP structure, because the gate-edge electric field was reduced by the gate-FP electrode. The dual-FP structure was slightly more effective to suppress the collapse phenomena than the single-gate-FP structure, because the two-step FP structure relaxes the electric-field concentration at the FP edge. These results show that the gate-edge peak strongly affects the on-resistance modulation. Although the FP edge peak also causes the collapse phenomena, its influence is weak.