Optical, electrical and structural properties of AlN thin films

Aluminum nitride is a very interesting material because of its wide band gap (6.3 eV), high decomposition temperature (2490°C), chemical stability (in air up to 700°C) and good dielectric properties. In the last decade considerable interest arose in the use of thin films of AlN for various applications, from hard coatings and overcoatings for magneto-optic media, to thin film transducers and GHz-band surface acoustic wave devices. Thin films of AlN have been prepared by several techniques: chemical vapor deposition, reactive evaporation, ion implantation and reactive sputtering. The reactive magnetron sputtering allows the growth of monocrystalline thin films with smooth surface due to the low substrate (Si) temperature, below 300°C, which prevents AlN grain growth. In this paper we present the UV-VIS optical properties and the AC electrical conductivity on AlN layers prepared by reactive magnetron sputtering. We also report results of structure, hardness measurements and dissolution rate