Preparation and characterization of thin films of NbO2

Thin films of NbO₂, with thicknesses ranging from 1000 to 20 000 Å, were prepared by r.f. sputtering powder targets of NbO₂ in a reducing atmosphere of 90vol.%Ar–10vol.%H. Transmission electron microscopy and X-ray diffraction studies of self-supported films indicate that the as-deposited material was amorphous. Compositional analysis, derived from interpretation of Rutherford back-scattering spectra and neutron activation analysis of films deposited onto vitreous carbon substrates, indicates a high degree of stoichiometry. The variation in the electrical conductivity with the rate of deposition is reported, and also a comparison is made between the electrical conductivity of the amorphous and crystalline phases of films of NbO₂.