Stacked Strongly Coupled GaN/SiC Cascode Device With Fast Switching and Reclaimed Strong d<i>v</i>/d<i>t</i> 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 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${Q}_{\text {G}}$ </tex-math></inline-formula>, thermally stable threshold voltage <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${V}_{\text {TH}}$ </tex-math></inline-formula>, smaller specific on-resistance <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${R}_{\text {ON. {SP}}}$ </tex-math></inline-formula>, 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 (<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${L}_{\text {P}}\text {)}$ </tex-math></inline-formula>, thereby suppressing the switching delay and switching loss. More importantly, the ultralow <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${L}_{\text {P}}$ </tex-math></inline-formula> 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 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${L}_{\text {P}}$ </tex-math></inline-formula>, an increased capacitive gate-to-drain coupling (i.e., <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${C}_{\text {GD}}\text {)}$ </tex-math></inline-formula> in the low-voltage gate control GaN HEMT would allow strong dv/dt control via changing the external gate resistance <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${R}_{\text {G}}$ </tex-math></inline-formula> 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.