Controlled growth of extended arrays of CoSi2 hexagonal nanoplatelets buried in Si(001), Si(011) and Si(111) wafers

Abstract

Because of their high electrical conductivity CoSi₂ nanostructures are potential candidates for preparing ordered nano-arrays to be used as electrode interconnectors and contacts in microelectronic devices. We here describe a controlled procedure for the endotaxial growth of hexagonal CoSi₂ nanoplatelets buried in differently oriented single crystalline Si wafers on which a Co-doped SiO₂ thin film was previously deposited. These nanomaterials were obtained by a clean procedure consisting of isothermal annealing at 750 °C under a He atmosphere of Co-doped SiO₂ thin films deposited onto the surface of three differently oriented flat Si substrates, namely Si(001), Si(011) and Si(111). Buried CoSi₂ nanoplatelets are in all cases spontaneously formed as a consequence of the diffusion of Co atoms into the silicon wafer and their reaction with host Si atoms. Our TEM and GISAXS analyses demonstrated that these arrays, irrespective of host Si orientation, consist of CoSi₂ hexagonal nanoplatelets in all cases parallel to Si{111} crystallographic planes. Additionally, the dimensions of the nanoplatelets were consistently determined by TEM and GISAXS for the three different host Si single crystal orientations.