Spectroscopic Characterization of Ultra-thin Al 2 O 3 /SiO 2 /Si Films by SR-XPS

Al 2 O 3 films (2-5nm) deposited on SiO 2 /Si (100) n-type substrate with thickness 500μm were characterized by Synchrotron Radiation- X-ray Photoelectron Spectroscopy (SR-XPS). Excitation energy 730eV show surface sensitive results compare to 1000eV. Using excitation energy 730eV, Al, Si, O core-level elements and their excited species were analyzed. Plasmon loss peak with energy separation (18.8-19.1eV) for Al2p main peak and (14.7-15.3eV) for Al2s main peak is likely due to bulk plasmon. XPS spectra of O1s peak showed different onset and energy seperation for each sample. Energy seperation between O1s peak and onset of plasmon is 8.4eV for 5nm lead to band gap of Al 2 O 3 layer. But and in case of 2nm this value is 9.2eV, hence, it is likely corresponds to SiO 2 interfacial layer.The reason for this might consider as top Al 2 O 3 form island rather than homogenous oxide layer.