Remarkable Increase in the Channel Mobility of SiC-MOSFETs by Controlling the Interfacial $\hbox{SiO}_{2}$ Layer Between $\hbox{Al}_{2}\hbox{O}_{3}$ and SiC

Abstract

The impact of a thin SiO2 layer inserted between Al2O3 and SiC on channel mobility in AI2O3/SiC MOSFETs was investigated. The remarkable increase in the channel mobility is demonstrated when the SiO2 thickness is around 1 nm. The thin SiO2 layer is formed by the thermal oxidation of the SiC substrate at 600 or 800degC in O2 atmosphere. The peak value of the field-effect mobility in AI2O3/SiO2/SiC MOSFETs is as high as 300 cm2 / (V ldr s). On the other hand, when the SiO2 layer is 2.0 nm, the field-effect mobility drastically reduces to 40 cm2/ (V ldr s), which is most likely due to the high interface trap density as seen in conventional SiO2/SiC MOSFETs.