Transport in Surface Passivated Porous Silicon Membranes

Permeable porous silicon membranes for ultra-and nanofiltration are realized by combination of microfabrication methods and self-organized nanostructuring. The material properties of native and surface passivated membranes are investigated for different substrate doping and fabrication conditions. Transport mechanisms in the membranes are investigated by permeability measurements for both gases and liquids. A transport model using an electric analog circuit as equivalent model is proposed for simulation of gas transport in nanostructured membranes. Adsorption and desorption isotherms are used to analyze the surface interaction between porous surface and adsorbate. As independent measure, AFM based distance-force measurements have been performed to investigate the adhesion forces as function of the surface properties. The influence of surface passivation on transport processes is evaluated.