Hole Injection Effect and Dynamic Characteristic Analysis of Normally Off p-GaN HEMT with AlGaN Cap Layer on Low-Resistivity SiC Substrate

A p-GaN HEMT with an AlGaN cap layer was grown on a low resistance SiC substrate. The AlGaN cap layer had a wide band gap which can effectively suppress hole injection and improve gate reliability. In addition, we selected a 0° angle and low resistance SiC substrate which not only substantially reduced the number of lattice dislocation defects caused by the heterogeneous junction but also greatly reduced the overall cost. The device exhibited a favorable gate voltage swing of 18.5 V (@I(GS) = 1 mA/mm) and an off-state breakdown voltage of 763 V. The device dynamic characteristics and hole injection behavior were analyzed using a pulse measurement system, and Ron was found to increase and V(TH) to shift under the gate lag effect.