Raman diagnostics of free charge carriers in boron-doped silicon nanowires

Raman spectroscopy is used to probe free charge carriers in layers of silicon nanowires (SiNWs) formed by metal-assisted chemical etching of crystalline silicon (c-Si) wafers followed by additional doping with boron. One-phonon Raman spectra of the boron-doped SiNWs are strongly modified due to the Fano effect that allowed us to determine the free carrier concentration in the nanowires in the range from 10(19) to 10(20) cm(-3), depending on the doping conditions. The micro-Raman mapping was used to determine the depth profile of charge carrier density along nanowires, which decreases toward the SiNWs/c-Si interface. The obtained results are discussed in view of possible applications of the Raman spectroscopy for express-diagnostics of doped Si nanostructures for photonics and thermoelectric applications.