High interfacial quality metal-oxide-semiconductor capacitor on (111) oriented 3C-SiC with Al2O3 interlayer and its internal charge analysis

Abstract

Metal-oxide-semiconductor (MOS) capacitors with various gate dielectrics were fabricated on (111) oriented n-type 3C-SiC. Deposited SiO2 by sputtering without an interlayer (IL) and thermally grown SiO2 show deteriorated capacitance–voltage (C–V) characteristics and high interface trap density (Dit) over 1011–1012 cm−2 eV−1. By inserting an IL, C–V and leakage current characteristics are improved. In particular, an atomic layer deposited (ALD) Al2O3-IL is suitable for 3C-SiC, which successfully achieved low Dit in the order of 1010 cm−2 eV−1. MOS capacitor with the same gate dielectric on n-Si shows contradictory characteristics. Structural analysis shows it is considered the flat and uniform interface at Al2O3/3C-SiC leads good electrical characteristics. The 3C-SiC MOS capacitor with Al2O3-IL showed slightly negative flatband voltage and it is induced by negative interfacial dipole generated at the Al2O3/3C-SiC interface. This 3C-SiC MOS structure can be fabricated at low process temperature (<600 °C), which means the overall process for device application can be designed more flexibly.