Chemical vapor deposition of niobium disulfide thin films

Atmospheric pressure chemical vapor deposition (APCVD) of niobium sulfide coatings was achieved on glass substrates from the reaction of NbCl(5) and S(SiMe(3))(2), tBu(2)S(2), tBuSH, or HSCH(2)CH(2)SH at 250-600degreesC. The niobium sulfide films grown at temperatures above 500degreesC were crystalline, and powder X-ray diffraction showed that two polytypes of NbS(2) were produced. The sulfur precursor used is fundamental to the polytype of NbS(2) obtained; films that are grown from the APCVD reaction of NbCl(5) and S(SiMe(3))(2) or tBu(2)S(2) at 500-600degreesC crystallize into the 1T structure, whereas those grown from the APCVD reaction of NbCl(5) and tBuSH or HSCH(2)CH(2)SH at 500-600 degreesC crystallize into the 3R structure. Energy dispersive X-ray analysis (EDXA) studies gave elemental ratios close to the expected 1:2 ratio for Nb:S. Scanning electron microscopy (SEM) revealed surface morphologies consistent with an island growth mechanism. The films were also characterized using Raman and X-ray photoelectron spectroscopy, both of which showed differences consistent with the formation of the two polytypes, 1T and 3R-NbS(2). (C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004.