Evolution of the morphology of Cu films on nanoporous Si pillar arrays

The morphology of nanoporous Si pillar arrays (Si-NPA) prepared by hydrothermal etching was characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and high-resolution TEM (HRTEM). The results reveal that Si-NPA has a silicon micro/nanometer composite structure, which makes it an ideal template. Si-NPA-based Cu nanocomposite systems (Cu/Si-NPA) were obtained by immersing Si-NPA in 0.01 M CuCl2 for 1, 5, 10 or 30 min at room temperature. Time-dependent morphological changes and the elemental composition of Cu/Si-NPA were analyzed by SEM, X-ray diffraction (XRD) and X-ray energy-dispersive spectroscopy (EDS). The number and the average size of Cu nanoparticles increased with the immersion time. Besides, Cu/Si-NPA inherited the morphological characteristics of Si-NPA. The results indicate that the morphological evolution of Cu/Si-NPA can be explained by the existence of microscopic electrochemical cells.