ИСТИНА

In this study the monocrystalline silicon and germanium was irradiated by ultrashort laser pulses in gases (helium and nitrogen) and liquids (water and liquid nitrogen). The choice of silicon as material of research is caused by biocompatibility and biodegradability of silicon nanoparticles, which in turn allows using it in biomedical field as contrasting agents in optical coherence tomography [1]. Ablation of germanium is interesting due to its high refractive index, possessing small effective mass and high mobility as compared to Si. [2]. Ge nanometer-sized structures have attracted tremendous attention due to their quantum confinement effects. Determination and comparison of the structural properties of silicon and germanium nanoparticles formed by means of picosecond laser ablation (1064 nm, 30 ps, 10 Hz, 17 J/cm2) is very important due its influence on optical and electrical properties of the particles. Raman spectra indicated the presence of mainly crystalline phase in the formed nanoparticles. The broadening and shifting of the Raman peak in all samples evidenced about the phonon confinement [3]. Using the calibration curve, we determined the size of nanoparticles by shift of peak. The size of nanoparticles corresponding to shift 2 cm-1 is equal to 6 nm, as confirmed by AFM studies. This work was supported by RFBR grant nos. 14–22–01086. [1] A.D. Krainov, P.D. Agrba, E.A. Sergeeva et al., Study of contrasting properties of nanoparticles for optical diffuse spectroscopy problems, Quantum Electronics, vol. 44, pp. 757-762 (2014). [2]A.F. Khan, M. Mehmood, A.M. Rana et al. Effect of annealing on structural, optical and electrical properties of nanostructured Ge thin films, Applied Surface Science, vol. 256, pp. 2031-2037 (2010). [3] V.A. Volodin, V.A. Sachkov, The improved model of localization of optical phonons in silicon nanocrystals, JETP, vol. 143, pp. 100-108 (2013).