Tuneable properties of aluminium oxynitride thin films

Abstract

In this subchapter is discussed some characteristics and properties of AlOxNy thin films produced by reactive DC magnetron sputtering. The films were deposited using Ar as working gas and a reactive gas mixture of N2+O2 (17:3). The reactive gas flow was varied in order to produce a wide range of chemical compositions. Sub-stoichiometric AlOxNy films, with CO+N/CAl atomic ratios up to 0.85 were produced, with Al-type crystalline structure. Transmission electron microscopy (TEM) analysis and X-ray photoelectron spectroscopy (XPS) spectra suggests that the films are a percolating network, composed by aluminium nanocrystals with different shapes and sizes embedded in an oxide/nitride matrix. The particular composition, structure and morphology of the films results in very different electrical properties, which can be explained using a tunnel barrier conduction mechanism for the electric charge transport, as well as distinct optical responses, such as an unusual large broadband absorption for some films.