Chemical interaction of pulsed laster deposited Co with the MoS2(0001) surface

Abstract The interaction between MoS 2 (0001) and pulsed laser deposited Co was studied with X-ray photoelectron spectroscopy, Auger electron spectroscopy, glancing angle high energy electron diffraction and scanning electron microscopy. 150 shots from a KrF excimer laser of wavelength 248 nm with fluence 10 J cm −2 aimed at a solid Co target resulted in an energetic source of Co which produced an overlayer of randomly oriented crystallites at the MoS 2 (0001) surface. The deposition of Co was accompanied by the formation of metallic Mo and a net depletion of S at the substrate surface. Annealing to 770 K induced the formation of a limited quantity of metallic Mo. We interpret the formation of metallic Mo after Co deposition and annealing to 770 K as caused by surface damage suffered by the substrate due to sputtering by the energetic ions and neutrals produced by pulsed laser deposition. Annealing did not drive a reaction between Co and MoS 2 (0001) to completion indicating that Co is not strongly reactive with MoS 2 (0001). The relative concentrations of species calculated from XPS and AES intensities after deposition were consistent with S incorporated in the overlayer film and metallic Mo situated at the overlayer/substrate interface. Annealing between 770 and 1070 K caused agglomeration of the Co overlayer, resulting in particles of average size 1000 A distributed on the basal plane, and a high concentration of Co at the step edges.