Reflection electron-energy-loss spectroscopy (ELS) and ultraviolet-photoemission spectroscopy (UPS) have been used to study the electronic properties of VNx(0.0x<0.96). Polycrystalline samples of several compositions have been fabricated with special care to avoid oxygen contamination. ELS is used to examine the collective oscillations ("plasmons") of the valence electrons, and one-electron core-level excitations, while angle-integrated UPS experiments using the resonance lines of He and Ne are used to probe the valence-band density of states. The ELS experiments are the first of this type on any of the transition-metal nitrides or carbides, while the UPS results are the first reported for VNx. Good overall agreement is found with the calculated density of states of Neckel et al. The experimental results seem to indicate that composition changes result in a reshaping of the hybridized (V-3d)+(N-2p) valence band rather than a simple rigid-bandlike shift of the Fermi level.
ASJC Scopus subject areas
- Condensed Matter Physics