Stacked Strongly Coupled GaN/SiC Cascode Device With Fast Switching and Reclaimed Strong dv/dt Control

We present a GaN-HEMT/SiC-JFET cascode device that replaces the most performance- and reliability-limiting low-mobility MOS channel of SiC MOSFETs with a high-quality GaN 2-D-electron-gas (2DEG) channel. Compared with SiC MOSFETs, the p-GaN gate-stack of the GaN/SiC cascode device delivers much lower gate charge ${Q}_{\text {G}}$ , thermally stable threshold voltage ${V}_{\text {TH}}$ , smaller specific on-resistance ${R}_{\text {ON. {SP}}}$ , and faster switching speed with substantially lower switching loss. A compact 3-D co-packaging solution with stacked GaN and SiC chips results in greatly reduced parasitic interconnection inductance ( ${L}_{\text {P}}\text {)}$ , thereby suppressing the switching delay and switching loss. More importantly, the ultralow ${L}_{\text {P}}$ is shown to play a critical role in reclaiming the dv/dt controllability, which has long been a prevalent issue for cascode devices that make them vulnerable to electromagnetic interference (EMI) issues. With an ultralow ${L}_{\text {P}}$ , an increased capacitive gate-to-drain coupling (i.e., ${C}_{\text {GD}}\text {)}$ in the low-voltage gate control GaN HEMT would allow strong dv/dt control via changing the external gate resistance ${R}_{\text {G}}$ in the gate driver circuit, which is the most simple and user-friendly control method in applications. The demonstrated GaN/SiC cascode device unveils an ultimate power device that unlocks the full potential of wide bandgap (WBG) semiconductors.