Structural and electronic properties of the 6H-SiC(0001)/Al_2O_3 interface prepared by atomic layer deposition

摘要

Al_2O_3 films were grown by Atomic Layer Deposition (ALD) on H-terminated 6H-SiC(0001). The films were characterized by photoelectron spectroscopy (PES) and admittance spec-troscopy measurements. The Si2p core level spectra of thin films indicate an abrupt interface. A band gap of 7.0 +-0.1 eV was measured for the deposited Al_2O_3 films. The valence and conduction band offsets were determined as 2.2 +- 0.1 and 1.8 +- 0.1 eV, respectively. The admittance spectroscopy measurements yield an interface state density that is lower than that observed with thermally grown SiO_2. Al_2O_3 films grown on substrates prepared by other methods (wet-chemical cleaning and H_2 plasma etching) exhibit inferior interface properties which stresses the importance of a proper surface preparation.