Abstract

Reaction of VCl₄ or VOCl₃ with water under atmospheric pressure chemical vapour deposition conditions in a cold-wall horizontal-bed reactor at 350–600 °C produces clear yellow V₂O₅ films. Films grown at temperatures in excess of 500 °C were crystalline and indexed with an orthorhombic unit cell a = 11.527(5), b = 4.382(5), c = 3.557(5) Å by glancing angle X-ray diffraction (XRD). X-Ray photoelectron spectroscopy (XPS) showed the presence of carbon, vanadium and oxygen in the surface layer. Depth profile sputtering removed the carbon and left only vanadium and oxygen with binding energies of 516.0 eV for V 2p_3/2 and 530.5 eV for O 1s. The vanadium to oxygen ratio, as determined by XPS, was 1∶2, indicating some preferential loss of oxygen during sputtering. Raman spectroscopy of the films showed identical patterns to bulk and magnetron sputtered V₂O₅ with bands at 697, 524, 478, 401, 300, 283, 194, 145 and 103 cm⁻¹. All films passed the Scotch tape test and could not be abraded with a paper towel or scratched with a scalpel. The visible and near IR reflectance spectra of the films show that they are more reflective than plain glass in the IR region. Transmission spectra of the films showed that they have equivalent transmission to plain glass but have a transmission cut off that is shifted 110 nm into the visible. The conditions established are attractive for the large scale rapid production of vanadium(V) oxide films.