Impacts of Al2O3/SiO2 interface dipole layer formation on the electrical characteristics of 4H-SiC MOSFET

In this letter, we demonstrated an approach to introduce a positive shift in transfer curves of lateral metal-oxide-semiconductor field-effect transistors (MOSFETs) on 4H-SiC (0001), without deterioration of channel conductance. With an additional Al2O3 thin film on thermally grown SiO2 after the nitridation process, a dipole layer was formed at the Al2O3/SiO2 interface, which induced the positive shift of flat-band voltage. The field-effect mobility of MOSFET was not changed after the Al2O3 fabrication process, which means that the quality of the nitrogen-passivated SiO2/SiC interface was not damaged by this process.