The one phonon Raman spectrum of silicon nanostructures

Porous silicon is a structurally complex material, in which effects of the pore topology on its physical properties are even controversial. In this work, we use the Born potential and the Green's function, both applied to a supercell model, in order to analyze the Raman response and the phonon band structure of porous silicon. In this model the pores are simulated by empty columns of atoms, in direction [001], produced in a crystalline silicon structure. A consequence of the model is the interconnection between silicon nanocrystals, and then, all the states are extended. However, the results show a behavior similar to the quantum confinement. Moreover, a dependence of the Raman spectra with the pore topology is observed. Finally, a shift of the main Raman peak towards lower frequencies is found, in agreement with experimental data.