Porous silicon (PS) is an artificially structured form of silicon to be used as a matrix for formation of nanocomposite materials by introducing different metals into PS. The fundamental understanding of the relationship between fabrication, structure and physical-chemical properties of porous silicon and porous silicon-based composites is essential for its further applications.
     In the present work we demonstrate Cu-Si nanocomposites formed by chemical displacement deposition of Cu into porous silicon matrix. The basic reaction of this process is the substitution of silicon atoms by copper atoms. The fundamental advantage of displacement deposition with respect to other deposition methods is that it can provide deep penetration of metals inside pore channels in PS.  Porous silicon layers with porosity from 30 % up to 80 % and with thicknesses from 1 to 10 micrometers were formed by anodizing of Czochralski (100) silicon wafers in HF electrolyte. PS porosity was controlled by varying the anodic current density in the range of 10 -150 mА/сm². After anodization, the HF electrolyte was replaced by a CuSO₄ + HF solution and Cu was deposited into porous silicon. SEM and X-ray microanalysis techniques were used to investigate the structure and elemental composition of Cu-Si samples. The distribution of the deposited metal, the structural features of Cu film and factors that influence Cu film structure are described. It is shown that variation of PS porosity and chemical displacement deposition regimes provide the formation of different nanocomposite PS-Cu structures. The potential fields of application of Cu-Si nanostructures are discussed: (a) electrical and mechanical Cu contacts with extremely high adhesion to PS; (b) nano- and micro-electromechanical systems; (c) assemblies of Si-nanowires carefully covered by Cu; (d) porous Cu membranes.

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