X-ray Photoelectron Spectroscopy Analyses of the Electronic Structure of Polycrystalline Ti1-xAlxN Thin Films with 0 ≤ x ≤ 0.96

Abstract

Metastable Ti1-xAlxN (0 ≤ x ≤ 0.96) alloy thin films are grown by reactive magnetron sputter deposition using a combination of high-power pulsed magnetron (HIPIMS) and DC magnetron sputtering (DCMS). Layers are deposited from elemental Ti and Al targets onto Si(001) substrates at 500 °C. All Ti1-xAlxN film surfaces are analyzed by x-ray photoelectron spectroscopy (XPS) employing monochromatic Al Kα radiation (hν = 1486.6 eV). Prior to spectra acquisition, TiAlN surfaces are sputter-cleaned in-situ with 4 keV Ar+ ions incident at an angle of 70° with respect to the surface normal. XPS results reveal satellite structures on the high binding energy side of the Ti 2p, Ti 3s, and Ti 3p core-level signals. The intensities of the primary Ti features (Ti 2p, Ti 3s, and Ti 3p) decrease with increasing AlN concentration such that the satellite peaks dominate spectra from films with x ≥ 0.67. The density-of-states at the Fermi level also decrease with increasing x indicating that the satellite peaks are due to screening of core holes created by the photoionization event. Film compositions, obtained using XPS sensitivity factors, agree to within ±3% with values determined by time-of-flight elastic recoil detection analyses.