Adjustment of Abrupt Drops in the C-V Curves of Various 4H-SiC MOSFETs and JBS Diodes

This study demonstrates the corresponding voltages to the abrupt drops in the C-V curves of the planar metal-oxide-semiconductor field-effect transistors (MOSFETs) and junction barrier Schottky (JBS) diodes without the P-pillar can be adjusted by designing the concentrations and structures of P-type regions, N-type junction field-effect transistor (JFET) regions, and N-type drift regions. When the concentrations of the upper N-type regions are much higher than those of the lower N-type regions and the widths are narrower than those of the N-type region beneath, both the C-V curves of MOSFETs and JBS show abrupt drops. From the measured results, the abrupt drop of the JBS becomes relatively steep and obvious when the concentration of the upper N-type region is 5 times higher than that of the lower N-type region in this study. The simulation results of the MOSFETs with multiple (equal to or more than 3) P- and N-type regions also demonstrate the multiple abrupt drops in the C-V curve under the above-mentioned conditions. The critical values of the concentrations and widths are decided in this study only. Additionally, the measured and simulated switching waveforms show when the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${V}_{\textit {ds}}$ </tex-math></inline-formula> corresponding to the abrupt drop decreases, the reverse recovery time (<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${t}_{\textit {rr}}\text {)}$ </tex-math></inline-formula> is shortened, and turn-on energy loss (<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${E}_{\textit {on}}\text {)}$ </tex-math></inline-formula> may be reduced.