Increased Channel Mobility in 4H-SiC UMOSFETs Using On-Axis Substrates

The achievement of high channel mobility in UMOSFETs by utilizing on-axis substrates is reported. UMOSFETs were fabricated on commercially available C-face 4H-SiC on-axis substrates. The MOS channels were formed on the single side of the trench sidewalls to be (1120), (1120), (1100), and (1100). By using on-axis substrates, channel mobility on (1120) was greatly improved to 66cm 2 /Vs, which is similar value (71cm 2 /Vs) on (1120). These values are the highest inversion channel mobility in 4H-SiC UMOSFETs ever reported. These results suggest that the channel plane should be close to the crystallographically accurate {1120} to increase channel mobility.