X-ray investigations on CoSi2 nano wires manufactured by focused ion beam synthesis


X-ray investigations on CoSi2 nano wires manufactured by focused ion beam synthesis

Grenzer, J.; Roshchupkina, O.; Fritzsche, M.; Mücklich, A.; Bischoff, L.

Nanowires and chains of nanoparticles are of emerging interest in nanoelectronics, nano-optics and plasmonics as well as for their monolithic integration into microelectronic devices. Epitaxial buried or surface CoSi2 layers in silicon can be formed by implanting Co in stoichiometric concentration and subsequent annealing. Ion beam synthesis allows the fabrication of submicron pattern, which can be formed either directly by a mass separated writing Co focused ion beam (FIB) or indirectly by a Ga FIB in combination with a thin Co film on the rear side of the Si wafer, providing the Co for the nanowire formation by diffusion.

We have studied the strain of the Si host lattice around a single nanostructure depending on their crystallographic orientation using high-resolution x-ray diffraction and TEM. The X-ray experiment was carried out using a highly focused beam (~0.5µm) at the beam line ID01 at ESRF. Surrounding a wire a peak was found indicating a tensile strain of approx. -1.4%.

The CoSi2 peak intensity is strongly modulated by moving from one wire to another. Moreover the diffuse scattered intensity around the Si bulk reflection is increased and is getting even more enhanced between the wires. A possible mechanism lying behind the CoSi2 structure formation is the lattice relaxation by stable dislocation loops. A zigzag like defect structure, characteristic for the formation of 311 defects, was identified by TEM at the grain boundary between the CoSi2 nanowires and the Si bulk.

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Publ.-Id: 16533