  A rough interface seems to be one of the possible reasons for low channel
mobility (conductivity) in SiC MOSFETs. To evaluate the mobility by interface
roughness, we drew a boundary line between amorphous insulator and crystalline
4H-SiC in a cross-sectional image obtained by a transmission electron
microscope (TEM), by using the deep learning approach of convolutional neural
network (CNN). We show that the CNN model recognizes the interface very well,
even when the interface is too rough to draw the boundary line manually. Power
spectral density of interface roughness was calculated.
