Paper AS-TuP9
Deposition and Characterization of Aluminum Oxynitride Optical Coatings

Tuesday, October 21, 2008, 6:30 pm, Room Hall D

Aluminum oxynitride (AlON) has received extensive attention due to its composition-dependent tunability in mechanical and optical properties. Aluminum oxynitride has been identified as a potential candidate material to replace sapphire (single crystal aluminum oxide) in various optical applications. However, it is still relatively expensive to fabricate bulk AlON by the conventional ceramic processing technique. The cubic AlON phase in the bulk material is obtained by a high temperature-synthesizing process to retain the crystal structure, which gives it optical, IR transparency and other attractive properties. It would be of importance for a number of applications, if the benefits of AlON properties could also be achieved in thin films. This thin film could then be applied on a variety of base substrates cost effectively. In this work, aluminum oxynitride coatings were deposited by magnetron sputtering followed by thermal treatments at different temperatures to evaluate phase conversions. Microstructures and phase constitution of both as-deposited and thermally treated AlON coatings were characterized by scanning electron microscopy (SEM), atomic force microscopy (AFM) and grazing incidence X-ray diffraction (GID). X-ray photoelectron spectroscopy (XPS) was employed to study the AlON coatings with respect to the stoichiometric composition and atomic bonding states. Mechanical properties such as Young’s modulus, hardness and coefficient of friction of AlON coatings were investigated by depth-sensing nano-indentation and nano-scratching experiments. Optical properties of AlON coatings were examined by measuring refractive index, reflectance and transmittance in both visible and infrared range. The mechanical and optical properties of AlON coatings were compared with the powder-processed AlON ceramics.