Dynamics of formation of the mosaic structure of porous silicon during prolonged anodic etching in electrolytes with an internal current source

Abstract

The spontaneous self-organization of a porous surface mosaic structure in the form of islands of oxidized por-Si nanocrystallites separated by silicon ledges has been observed during prolonged anodic etching of p-Si (100) in electrolytes with an internal current source. The por-Si mosaic structure is spontaneously formed as a result of relaxation of an elastically strained layer of the porous surface. The self-organization of the mosaic structure of the por-Si surface, island sizes, and the period of their arrangement are controlled by a number of factors arising in the complex heterophase system electrolyte/por-Si/c-Si/during etching, i.e., the spatio-temporal distribution of point defects of interstitials I _Si and vacancies V _Si in the c-Si surface region, the formation of capillary fluctuation forces at the electrolyte/por-Si/c-Si/interface, the elastic deformation forces induced by the lattice parameter mismatch between the oxidized por-Si nanocrystallites and the c-Si matrix. The conditions responsible for the manifestation of these forces depend on the self-consistent parameters of etching of the complex heterophase electrochemical system electrolyte/por-Si/c-Si/with an internal current source, including the electrode characteristics and cell parameters.