Enhanced Inversion Mobility on 4H-SiC Using Phosphorus and Nitrogen Interface Passivation

Low interface trap density and high channel mobility on nonpolar faces of 4H-SiC, such as the (11[2̅]0) a-face, are of fundamental importance in the understanding of SiC MOS devices. It is also critical for high-voltage trench power MOSFET development. We report new results on the passivation of the SiO₂/a-face 4H-SiC interface using phosphorus, yielding field effect mobility of ~125 cm₂/V · s. We also revisit the conventional NO passivation, for which a mobility of ~85 cm₂/V · s was achieved on the a-face. These results not only establish new levels of mobility in SiC MOSFETS but also lead to further insights into factors currently limiting SiC inversion layer mobility.