Growth of thin layers of metal sulfides by chemical vapour deposition using dual source and single source precursors: routes to Cr2S3, alpha-MnS and FeS

The growth of thin layers of the transition metal sulfides Cr2S3, alpha -MnS and FeS by Chemical Vapour Deposition (CVD) is reported. Layers of Cr2S3 in the rhombohedral or trigonal form have been grown onto Pyrex, molybdenum or aluminium substrates using the single-source precursor Cr(S2CN(C2H5)(2))(3) in a low-pressure flow reactor. The temperature of the precursor was held at 255 degreesC and the substrate was heated to 450 degreesC for these experiments. The nature of the layer formed was determined by a combination of EDX analysis and glancing angle XRD. Growth rates up to 10 mum h(-1) were achieved. In a separate series of experiments thin layers of alpha -MnS and FeS have been grown onto Pyrex substrates using propylene sulfide (C3H6S) as the sulfur source and CpMn(CO)(3) (Cp = eta -C5H5) or Cp2Fe as the metal source using a CVD reactor under a flow of nitrogen gas. An approximately 1:1 molar ratio of C3H6S and CpMn(CO)(3) and a substrate temperature of 410 degreesC gave a growth rate of alpha -MnS of some 4 mum h(-1) and a crystalline layer as shown by EDX analysis and powder XRD. However, increasing the flow rate of the sulfur source or decreasing that of the metal source gave rise to sulfur-rich layers. Layers of FeS were grown on Pyrex substrates from C3H6S and Cp2Fe with a molar ratio of reactants of 1:3 or higher and a substrate temperature of 410 degreesC. A growth rate of around 2.5 mum h(-1) was achieved.