Formation of NiSi₂ nanocrystalline platelets endotaxially growth in Si(001) wafer

Full text: The interest in studies of silicide nanocrystals integrated to the Si has been increased in the last decades. The reason is that silicides like NiSi₂ and CoSi₂ present high electrical conductivity, excellent thermal stability and are structurally compatible with the crystalline lattice of Si making these nanocomposites potential candidates for applications in nanoelectronic [1-2]. Therefore, new reproducible synthesis methods which require greater control of silicide nanoparticles size and shape are currently being sought for application in the processes of producing these devices in large scale. In this work an alternative method is proposed to obtain NiSi₂ nanoplatelets embedded in single crystalline Si wafers having the shape of nearly regular hexagons and small size dispersion. The method of preparation consists in the deposition of a Ni-doped thin film on a Si(001) wafer followed by thermal treatments to promote the diffusion on Ni atoms into Si substrate and subsequent formation of the NiSi₂ nanoplatelets. The sample was characterized by X-ray reflectivity and grazing incidence small-angle X-ray scattering. The results showed the NiSi₂ nanoplatelets grow coherently with crystalline lattice of Si having their hexagonal surface parallel to the lattice planes of the Si{111} crystallographic form and one of their lateral sides intercepting the wafer surface. The values of the lateral size and thickness of the nanohexagons determined from X-ray scattering analysis were L = (28.0 ± 0.6) nm and t = (3.0 ± 0.5) nm, respectively. References: [1] G L. P. Berning and L. L. Levenson. Diffusion of Nickel in Silicon below 475°C. Thin Solid Films, 55, (1978), pp. 473-482. [2] C. Y. Lee, et al. Free-Standing Single-Crystal NiSi₂ Nanowires with Excellent Electrical Transport and Field Emission Properties. J. Phys. Chem. 113, (2009) 2286–2289. (author)