Spectroscopic Characterization of Ultra-thin Al₂O₃/SiO₂/Si Films by SR-XPS

Abstract

Al2O3 films (2-5nm) deposited on SiO2/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 Al2O3 layer. But and in case of 2nm this value is 9.2eV, hence, it is likely corresponds to SiO2 interfacial layer.The reason for this might consider as top Al2O3 form island rather than homogenous oxide layer.