Structural investigation of high-transmittance aluminum oxynitride films deposited by ion beam sputtering

Abstract

Aluminum oxynitride films were deposited by ion beam sputtering technique at room temperature. The optical properties and morphologies of the aluminum oxynitride films were studied and reported previously. It was found that the optical properties are closely related to the O contents in the films. In this study, the structures of the films were investigated by X-ray diffractometer and XPS. Three oxidation states of N1s in oxynitride films, N +, N2+ and N3+, were clearly deduced from N1s spectra in the amorphous films fabricated under various oxygen partial pressures (PO2). To our knowledge, three oxidation states of N1s have not been simultaneously observed and reported in the aluminum oxynitride films previously. Corresponding bonding variations in Al2p and O1s spectra indicated more oxygen in oxynitride in the film as PO2 increases. Three aluminum oxynitride networks, AlO2N, AlO2.5N and AlO3N were deduced. Optical properties of aluminum oxynitride films resemble those of AlN and Al 2O3 films when PO2 is low and high during the deposition. The refractive indices and extinction coefficients of the aluminum oxynitride films can be adjusted by using proper PO2 during the film depositions. Copyright © 2010 John Wiley & Sons, Ltd.