Transverse component of the electrical conductivity of porous silicon — I

Abstract

The study of transport in porous materials is a very challenging problem. In particular, the understanding of electric transport in porous silicon is fundamental for its promising technological impact. In a previous work we obtained an analytical expression for the axial effective electrical conductivity of a model simulating porous silicon (PS). We used the averaging volume method that has proven to be successful in treating fluid transport in porous media. The PS model was based on experimental information about this new material's structure and experimental data for crystalline Si and hydrogenated a-Si thin films. With this method we can calculate the bulk and the surface contribution to the tensorial effective conductivity. Here we present the transverse effective conductivity results where percolation effects can be observed, using the same method and model. However, in the XY plane the calculation is more complicated and it can only be solved numerically. We find that there is a range at low porosities where the effective electrical conductivity can be enhanced due to the surface contribution.