Anomalously anisotropic channel mobility on trench sidewalls in 4 H - Si C trench-gate metal-oxide-semiconductor field-effect transistors fabricated on 8° off substrates

Metal-oxide-semiconductor (MOS) channel properties in 4 H - Si C trench-gate MOS field-effect transistors fabricated on 8° off substrates were characterized. The MOS channel was formed only on one side of the trench sidewalls. The MOS field effect transistor performance depended strongly on the MOS channel planes of ( 11 2 ¯ 0 ) , ( 1 ¯ 1 ¯ 2 0 ) , ( 1 1 ¯ 00 ) , and ( 1 ¯ 100 ) . The highest channel mobility of 43 cm 2 ∕ V s was obtained on ( 11 2 ¯ 0 ) . However, only a half value of 21 cm 2 ∕ V s was observed on ( 1 ¯ 1 ¯ 20 ) , which is the opposite face to ( 11 2 ¯ 0 ) . The anomalously anisotropic channel mobility is discussed based on the deviation from the crystallographically accurate { 11 2 ¯ 0 } plane caused by the combination of substrate off angle and sloped trench sidewalls.