Titanium aluminum nitride (Ti-Al-N) films were deposited by reactive magnetron cosputtering. Core-level photoelectron spectroscopy and valence-band photoelectron spectroscopy served to characterize these films. Samples can consist of one single nanocrystalline phase, the substitutional solid solution (Ti, Al)N. There exist also ranges of compositions where a nanocomposite material is formed. This inhomogeneous film structure is indicated by shifts of the Fermi edge, which can be explained by a one-electron charging effect of nanometer-sized metallic clusters being embedded in an electrically insulating matrix. The multitude of possible chemical bonding situations within the ternary system are reflected by the core-level spectra. Complex Ti $2p$ line shapes may also be due to the screening properties of the conduction electrons. Valence-band spectra reveal electronic properties from metallic to dielectric character, depending on the elemental composition. In the case of nitrogen-saturated films the spectral intensity close to the Fermi edge is correlated with the Ti content.

• Received 20 July 2000

DOI:https://doi.org/10.1103/PhysRevB.63.115413