Fabrication and photoluminescence of hyperbranched silicon nanowire networks on silicon substrates by laser-induced forward transfer

The structure and photoluminescent properties of films obtained by modified laser-induced forward transfer of silicon are presented. Strong variations in structure with ambient gas composition are observed: in Ar, porous films of mutually agglomerated silicon nanoparticles are observed, while in air the films consist of a network of hyperbranched nanowires (SiHBNWs) whose diameter varies periodically along their length, and which are composed of crystalline silicon nanoparticles surrounded and interconnected by amorphous silicon oxide of varying stoichiometry. The mechanisms of formation of the structures are dwelt upon and explained in term of dynamics within the plume. For the SiHBNWs, the pioneering use of fluorescence imaging was employed to obtain evidence for the photoluminescence originating from the crystalline nanoparticles themselves, and origins of the emission bands are thus attributed to radiative recombination of excitons at the Si/SiO2 interface accordingly