Photoemission study of the electronic structure of stoichiometric and substoichiometric TiN and ZrN

The electronic structure of stoichiometric and substoichiometric titanium nitride (TiN) and zirconium nitride (ZrN) have been studied with ultraviolet and X-ray photoelectron spectroscopy. The valence-band spectrum of stoichiometric TiN is compared with calculations of the density-of-states. Peak positions and widths agree quite well, whereas photon-energy-dependent intensity variations do not seem to follow the trends expected from the atomic photoionization cross-sections. The more tightly bound metal core lines are shifted to higher binding energies by approx 1.4 eV in the compounds compared to those in the pure metals. An extra peak approx 2 eV binding energy was found in the substoichiometric TiN and ZrN samples and assigned to an occupied defect state. For TiN sub 1--x the peak intensity is comparable to that of the peak at the Fermi level, whereas for ZrN sub 1--x this peak is broader and less pronounced. 44 ref.--AA