Femtosecond laser printing of single Ge and SiGe nanoparticles with electric and magnetic optical resonances

A recently introduced femtosecond laser printing technique was further developed for the fabrication of crystalline single Ge and SiGe nanoparticles (NPs). Amorphous Ge and SiGe thin films deposited by e-beam evaporation on a transparent substrate were used as donors. The developed approach is based on a laser-induced forward transfer process, which provides an opportunity for NP-controlled positioning on different types of receiver substrates. The size of the generated nanoparticles can be varied from about 100 to 300 nm depending on the laser pulse energy and wavelength. The crystallinity and composition of nanoparticles are both confirmed by the Raman spectroscopy measurements. The experimental visible scattering spectra of single nanoparticles are found to be well coincident with theoretical simulations performed on the basis of Mie theory. It is demonstrated that Ge and SiGe nanoparticles are characterized by electric and magnetic dipole resonances in the visible and near-infrared spectral ranges, wh...