Atmospheric pressure chemical vapour deposition of vanadium diselenide thin films

Atmospheric pressure chemical vapour deposition (APCVD) of vanadium diselenide thin films on glass substrates was achieved by reaction of [V(NMe2)4] and tBu2Se. X-ray diffraction showed that the VSe2 films were crystalline with preferential growth either along the (1 0 1) or the (1 1 0) direction. Energy-dispersive analysis by X-rays (EDAX) gave a V:Se ratio close to 1:2 for all films. The films were matt black in appearance, were adhesive, passed the Scotch tape test but could be scratched with a steel scalpel. SEM showed that the films were composed of plate-like crystallites orientated parallel to the substrate which become longer and thicker with increasing deposition temperature. Attempts to produce vanadium selenide films were also performed using tBu2Se and two different vanadium precursors: VCl4 and VOCl3. Both were found to be unsuitable for producing VSe2 from the APCVD reaction with tBu2Se. The VSe2 showed charge density wave transition at 110-115 K.