ИСТИНА

Silicon nanowires (SiNWs) were prepared by metalassisted chemical etching (MACE) of crystalline silicon (cSi) wafers with crystallographic orientation (100), ptype conductivity and doping density about 110 mOhm*cm in solutions based on AgNO3/HF during 30 sec and H2O2/HF during 20–180 min. Micrographs in scanning electron microscope showed that SiNWs had porous structure and consisted of a plurality of intersecting small nanocrystals and pores. Diameters of SiNWs were 50300 nm. SiNWs were investigated by means of the Raman scattering spectroscopy under excitation with wavelength of 632.8 nm. An asymmetrical shape of the Raman spectrum of SiNWs was observed and it was explained by evidences of the Fano resonance. A comparison of the Raman spectra for SiNWs and cSi substrates allows us to estimate the concentration of free charge carriers in SiNWs of the order of 10^19 cm^3. The total reflectance spectra of SiNWs at wavelength longer than 1000 nm indicate also the high concentration of free charge carriers. The reflectance values did not significantly depend on the thickness of SiNWs layer. This fact confirms the preservation of free charge carriers in the samples prepared for long etching time. The observed high concentration of free charge carriers in SiNWs can be useful for their applications in microand optoelectronics. The reported study was funded by RFBR according to the research project No. 160000001 мол_a.