Demonstration of SiC n-channel MOSFETs fabricated on a high-purity semi-insulating substrate and investigation of the short-channel effects

Abstract N-channel MOSFETs fabricated on a high-purity semi-insulating (HPSI) 4H-SiC substrate were demonstrated. The fabricated MOSFETs exhibited normally-off transistor operation and the peak field effect mobility ( μ FE,peak ) was 30 cm 2 V −1 s −1 , which was lower than that of the p − -body MOSFETs ( N A = 2 × 10 15 cm −3 ). The critical channel length ( L crit ) was 1.48 μm for the HPSI MOSFETs, which was shorter than that for the p − -body MOSFETs. In the HPSI MOSFETs, electrons trapped by the compensating defects in the HPSI substrate increase as the Fermi level moves up, which may be the main cause for the resulting low μ FE,peak and short L crit .