The use of dopant as a catalyst in the vapour-liquid-solid mode of growth offers a unique way to dope simultaneously the growing nanostructure. This paper reports the use of Mn as a catalyst to grow ZnS nanostructures and simultaneously doping it. It was also shown here that the diffusion rate of Mn in ZnS could be varied to compete with the growth rate of the nanostructures. The diffusion of Mn was found to depend strongly on the Mn layer thickness. The composition of nanowires was determined from X-ray diffraction and X-ray photo-emission spectroscopy measurements. X-ray photo-emission spectroscopy revealed that Mn diffused only on the surface forming MnS2 compound and its concentration on the surface of nanowires showed a strong dependence on its droplet size. The thermodynamic models were used to examine the interplay of the growth of ZnS nanostructures and Mn diffusion in them. The results showed that uniform doping during the growth could be achieved by carefully tuning the growth temperature and the catalyst layer thickness or catalyst droplet size.

Competitive Role of Mn Diffusion with Growth in Mn Catalyzed Nanostructures. S.Rehman, M.Hafeez, U.Manzoor, M.A.Khan, A.S.Bhatti: Journal of Applied Physics, 2012, 111[8], 084301