TEM characterisation of porous silicon.

In this work, the results of a structural investigation by transmission electron microscopy of porous silicon and porous silicon-based devices is reported. This investigation covers a wide range of porous silicon materials going from photoluminescent micro- or meso-porous silicon to macro-porous layers as well as some recent applications of this material for the fabrication of porous silicon and Si/SiO2 superlattices, suspended thick membranes and gas sensor devices. It appears that the structural investigation technique here employed, is a fundamental tool for the optimisation of the technological processing of this material. From the results reported in this work, a quite comprehensive view of the potentialities and limitations of the applications of porous silicon in the field of optical and gas sensor devices should also emerge. Finally, some solutions to the problems usually met during the technological processing of this material are proposed.