Atmospheric pressure chemical vapour deposition of vanadium nitride and oxynitride films on glass from reaction of VCl4 with NH3

Abstract

Atmospheric pressure chemical vapour deposition of vanadium nitride and oxynitride coatings was achieved on glass substrates from the reaction of VCl4 and NH3 at 350–650°C. The coatings show excellent uniformity, surface coverage, adherence and a range of colours (yellow, blue–silver) dependent on deposition temperature and film thickness. Growth rates were of the order of 1 µm min−1. All films deposited at greater than 450°C were crystalline, single phase with an fcc NaCl diffraction pattern, a = 4.065–4.116(2) A. Scanning electron microscopy (SEM) revealed different film thicknesses and surface morphologies consistent with an island growth mechanism. X-Ray photoelectron spectroscopy (XPS) revealed that individual samples were homogeneous. Compositional variations between films were related to reaction conditions; VN0.8O0.18–VN0.56O0.8. XPS binding energy shifts were seen for V 2p at 513.3 eV for O 1s at 530.8 eV and for N 1s at 397.1 eV and were largely invariant between samples. Energy dispersive X-ray analysis (EDXA) and electron probe studies gave elemental ratios that were in agreement with the XPS measurements, indicating no chlorine incorporation. Raman spectra showed a broad band at 600 cm−1. Sheet resistance measurements indicated that all films were metallic. Optically, the films were reflective in the range 800–2600 nm and showed reasonable transmission in the range 300–800 nm. The films show promise as solar-control coatings.