Abstract

The growth of thin layers of the transition metal sulfides Cr₂S₃, α-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 °C and the substrate was heated to 450 °C 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 µm h⁻¹ were achieved. In a separate series of experiments thin layers of α-MnS and FeS have been grown onto Pyrex substrates using propylene sulfide (C₃H₆S) as the sulfur source and CpMn(CO)₃ (Cp = η-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 °C gave a growth rate of α-MnS of some 4 µm 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 °C. A growth rate of around 2.5 µm h⁻¹ was achieved.