Tuning the pore wall morphology of mesoporous silicon from branchy to smooth, tubular by chemical treatment

The effect of chemical treatment on physical and chemical properties, i.e., pore diameter, porosity, specific surface area, and chemical bonding of electrochemically formed mesoporous silicon were investigated by using of nitrogen sorption isotherm, scanning electron microscopy, and Fourier transform infrared spectroscopy. The adsorption isotherms measurements show the general behavior found for the porous materials, but at the same time, they exhibit clear differences following different chemical treatments of porous layer. It was clearly observed from Fourier transform infrared spectroscopy that the chemical environment of porous silicon wall changes significantly after chemical treatment. In scanning electron microscopy images, we see that the rough dendritic structure of the pore walls is modified to smooth tubular pore wall structure on chemical treatment. The changes in nanocrystalline porous silicon were also clearly observed by an asymmetric broadening and shift of the optical silicon phonons in Raman spectra. Furthermore, changes are observed in the multiphonon regime due to surface assisted multiphonon processes, which are enhanced in highly porous silicon. The chemically modified porous silicon samples suggest possibilities of use as a porous matrix for fundamental study and technological application.

DDC Class

530: Physik

More Funding Information

This work has been supported within the Priority Program 1164 of the German Research Foundation DFG, Nano- and Microfluidics, Grant No. Hu850/2.

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Tuning the pore wall morphology of mesoporous silicon from branchy to smooth, tubular by chemical treatment