TEM and HREM study of 3D silicon and platinum nanoscale assemblies in dielectric opal matrix
In this paper, regular systems of silicon and platinum assemblies have been fabricated in a three-dimensional (3D) void sublattice of synthetic opal. Silicon was introduced into opal pores by thermal CVD. The filling of the opal pores was varied by changing the parameters of the CVD process. The samples were also filled with platinum from a solution of platinum tetrachloride in ethanol in order to fabricate metal contact to silicon. A detailed TEM and HREM structural study of opal-Si and opal-Pt-Si composites was carried out using JEM4000EXII and JEM2010 electron microscopes. It was found that silica spheres in regular opal-Si composites are uniformly covered with a nanocrystalline silicon layer up to 25-30 nm thick. To form the Pt-Si contact, the silica spheres were coated with platinum before being embedded in silicon. The presence of a substructure in the silica spheres ensures a uniform distribution of platinum over the sphere surface.