A one-dimensional surface relief with a 1.20  ±  0.02 µm period was formed in amorphous hydrogenated silicon films as a result of irradiation by femtosecond laser pulses (1.25 µm) with a fluence of 0.15 J cm−2. Orientation of the formed structures was determined by the polarization vector of the radiation and the number of acting pulses. Nanocrystalline silicon phases with volume fractions from 40 to 67% were detected in the irradiated films according to the analysis of Raman spectra. Observed micro- and nanostructuring processes were caused by surface plasmon–polariton excitation and near-surface region nanocrystallization, respectively, in the high-intensity femtosecond laser field. Furthermore, the formation of Si-III and Si-XII silicon polymorphous modifications was observed after laser treatment with a large exposure dose. The conductivity of the film increased by three orders of magnitude at proper conditions after femtosecond laser nanocrystallization compared to the conductivity of the untreated amorphous surface. The conductivity anisotropy of the irradiated regions was also observed due to the depolarizing contribution of the surface structure, and the non-uniform intensity distribution in the cross-section of the laser beam used for modification.

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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 1019 to 1020 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.