Interface formation of Al2O3 on carbon enriched 6H-SiC(0001): Photoelectron spectroscopy studies

The physical vapor deposition method is used to form layers of Al2O3 insulator on carbon enriched (0001)-oriented 6H-SiC substrate at room temperature. The substrate surface and the Al2O3/6H-SiC interface are characterized in situ by X-ray photoelectron spectroscopy (XPS) and ultraviolet photoelectron spectroscopy (UPS). The electron affinity (EA) of the pre-annealed up to 800 degrees C under ultrahigh vacuum 6H-SiC(0001) surface and the 7 nm thick Al2O3 layer deposited on the substrate amounts to 4.1 eV, and 1.9 eV respectively. The formation of the Al2O3 compound is confirmed by the appropriate binding energies of Al-2p and O-1s core level lines, which are 75.6 eV and 532.3 eV, respectively. The valence band offset (VBO) of the Al2O3/6H-SiC interface is found to be -3.2 eV and the conduction band offset is calculated to be 0.7 eV.