Charge Distribution in the Single Crystalline Ti2AlN Thin Films Grown on MgO(111) Substrates

Single crystalline Ti2AlN thin films have been grown on MgO(111) substrates at 750 °C using DC magnetron sputtering from a Ti2Al alloy target in a mixed N2/Ar plasma. X-ray diffraction, atomic force microscopy, and transmission electron microscopy demonstrate layered growth of a Ti2AlN{0002} thin film on the MgO(111) substrate. X-ray photoelectron spectroscopy detects a TiN-like conducting nature of the Ti2AlN thin film. However, the binding energies (BEs) of Ti 2p3/2 and Al 2p have shifted to 454.7 ± 0.2 and 72.3 ± 0.2 eV, respectively, lower than their corresponding values in nitrides (TiN and AlN). The BE of Al 2p is even lower than that in metallic Al. The unusual shifts are attributed to charge transfer from Ti to Al as shown by the density functional theory calculations.