Influence of Laser Radiation Power on Raman Spectra of Nanostructured Silicon Wires with Crystallographic Orientation (111)

In this paper an experimental study of laser irradiation power effect on the Raman spectra of nanostructured porous silicon wires (NPSW) obtained on n-Si(111) is reported. NPSW were obtained by modified metal-assisted electrochemical etching of c-Si. The laser radiation power varied from 0.064 mW to 5.94 mW. Analysis of the spectra showed the following at low power density the received signal is poorly distinguishable against the background of the main mode for Si at 520 cm
⁻¹
. As the power increases, one can observe characteristic shifts of the entire Raman spectrum towards low frequencies up to 483 cm
⁻¹
for the fundamental optical phonon mode. Repeated studies at lower powers did not reveal significant structural changes in the NPSW. Based on the data obtained, new possibilities of the technique for characterizing of NPSW by the Raman scattering are discussed.