Atmospheric Pressure Chemical Vapour Deposition of NbSe2 Thin Films on Glass

Atmospheric pressure chemical vapour deposition (APCVD) of niobium selenide films on glass substrates was achieved by reaction of di‐tert‐butyl selenide with NbCl5 at 250–600 °C. X‐ray diffraction showed that the NbSe2 films were crystalline and of the 2Ha poly‐type with cell constants close to those expected (a = 3.44 Å; c = 12.58 Å). Marked preferred orientation along either (101) or (200) was noted at higher deposition temperature and this unexpectedly varied depending on distance from the reactor inlet. The films produced at 600 °C showed exactly the Nb/Se ratio expected for NbSe2 by energy dispersive analysis by X‐rays. The films deposited at the substrate temperatures of 500 °C or less were selenium rich with a niobium to selenium ratio of 1:2.5. The films produced at 600 °C were dark‐green, powdery and poorly adhesive. The films produced at 500 °C and below were dark‐brown matte in appearance, they passed the Scotch tape test, but could be scratched with a steel scalpel. SEM showed that the films were composed of plate‐like crystals, which become longer and thicker with increasing deposition temperature. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)