Investigation of interface state density near conduction band edge of 4H-SiC MOSFET based on inversion capacitance and drain-current characteristics

We propose a simple method to evaluate interface state density ( D it ) near the conduction band edge of 4H-SiC MOSFETs, which is difficult to observe by conventional methods although it degrades device characteristics. We focus on a capacitance–voltage method with inversion capacitance, applying high voltage to a set reference point where almost all traps are occupied and sweeping downward gradually. Our method is applicable for mass production because of the convenient sequence. We also demonstrate that the device characteristics calculated based on the extracted D it are in good agreement with the measured characteristics.