We present a new method for making monodisperse highly spherical poly-crystalline silicon (Si) nanoparticles dispersed in solution and a method for trapping, moving and printing these nanoparticles on a substrate. Spherical Si nanoparticles with low dispersion in size (<3.5%) and diameter of 130 nm and 210 nm were fabricated using combined hole-mask colloidal lithography and laser-induced transfer. The particles are
highly crystalline and possess electric and magnetic dipole resonances in the visible spectrum varying with the diameter. They could be trapped in 2D against a substrate using an optical tweezer and then printed onto the substrate by means of radiation pressure. The proposed method pave the way to the use of optical forces for assembling complex resonant dielectric nanostructures with engineered optical properties.
This work was supported by the A*STAR SERC Pharos programme (grant number 152 73 00025; Singapore), the Knut and Alice Wallenberg Foundation, Chalmers Excellence Initiative Nano and the Swedish Research Council.