ABSTRACT
The open porous structure and very large specific surface area of porous silicon (PSi) have driven scientists to introduce different foreign substances into its pores to fabricate PSi-based composite and hybrid materials (Hérino et al. 1997; Hérino 2000). Under this approach, PSi plays a role of host material, which receives foreign substances as “guests”: metals, semiconductors, and carboncontaining materials (polymers, fullerenes, carbon nanotubes, and graphene). Nowadays in most cases, PSi is considered a template, that is, a type of host material with the structure that defines a shape of a “guest” substance. Elongated pores of PSi provide a formation of nanowires (NWs) and nanotubes (NTs) with high aspect ratio (more than 1:100) or formation of nanoparticles (NPs) at initial stages of the filling process. Process flow for fabrication of NWs, NTs, and NPs using PSi as template is shown schematically in Figure 9.1. The aims of filling of PSi pores are: (1) to obtain 1D nanostructures with high aspect ratio and anisotropy of properties; (2) to fabricate 1D and 0D structures showing unusual properties caused by quantum size effects; (3) to provide an electrical contact to the whole PSi surface; and (4) to integrate composite and hybrid materials with CMOS, MEMS, and NEMS devices. Composite material is a mixture of similar kinds of materials while hybrid consists of different kinds of materials (organic and inorganic) with chemical bonds between them. The main distinction between composite and hybrid is that the second one possesses properties, which do not exist in either of its parent components (Drisko and Sanchez 2012).
