CHEMICAL INTERACTION OF PULSED-LASER DEPOSITED CO WITH THE MOS2(0001)SURFACE

The interaction between Mos(2) (0001) and pulsed laser deposited Co wa s studied with X-ray photoelectron spectroscopy, Auger electron spectr oscopy, glancing angle high energy electron diffraction and scanning e lectron microscopy. 150 shots from a KrF excimer laser of wavelength 2 48 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 orie nted crystallites at the MoS2(0001) surface. The deposition of Co was accompanied by the formation of metallic Mo and a net depletion of S a t the substrate surface. Annealing to 770 K induced the formation of a limited quantity of metallic Mo. We interpret the formation of metall ic Mo after Co deposition and annealing to 770 K as caused by surface damage suffered by the substrate due to sputtering by the energetic io ns and neutrals produced by pulsed laser deposition. Annealing did not drive a reaction between Co and MoS2(0001) to completion indicating t hat Co is not strongly reactive with MoS2(0001). The relative concentr ations of species calculated from XPS and AES intensities after deposi tion were consistent with S incorporated in the overlayer film and met allic Mo situated at the overlayer/substrate interface. Annealing betw een 770 and 1070 K caused agglomeration of the Co overlayer, resulting in particles of average size 1000 Angstrom distributed on the basal p lane, and a high concentration of Co at the step edges.