Preparation and photoelectron spectroscopy study of UNx thin films

Abstract Thin films of UN and U 2 N 3 were prepared by reactive DC sputtering of U in N 2 -containing atmosphere. The composition of the films was modified by varying the partial pressure of N 2 . 4f-Core-level photoelectron spectra as well as valence-band spectra obtained with HeII and HeI photoexcitation confirm the itinerant character of the 5f-electronic states in UN, showing a high density of states at the Fermi energy. The 4f peaks in U 2 N 3 are shifted towards higher binding energy and are symmetric, indicating a low density of states at the Fermi level. Valence-band spectra show indeed a maximum of 5f emission at 0.8 eV below the Fermi level, but some 5f intensity at the Fermi level is preserved, contradicting full 5f localisation.