Laser-Assisted on demand growth of semiconducting nanowires

We present laser-Assisted direct synthesis of nanowires with site-, composition-, and shape-selectivity on a single substrate by employing a spatially confined laser heat source. Laser-Assisted nanowire growth based on vapor-liquid-solid mechanism is conveniently studied with multiple growth parameters such as temperature, time, and illumination direction. On-demand direct integration of silicon and germanium nanowires are demonstrated in a hetero-Array configuration by simply switching the reactant gases as the growth of nanowires is limited within the heat-Affected zone induced by the laser. Since laser-induced local temperature field is able to drive the individual growth, each germanium nanowire is successfully synthesized with distinctively different geometric features from cylindrical to hexagonal pyramid shape. By regularly patterning gold catalysts prepared by electron beam lithography on Si(111), especially, we accomplished site- And shape-selective direct integration of germanium nanowires on a single substrate in vertical architecture. Considering that blanket furnace heating only produce nanowires with uniform size and shape, therefore, our work shows a route toward the facile fabrication of multifunctional nanowire based devices.