Directionally Integrated VLS Nanowire Growth in a Local Temperature Gradient

Abstract

Going straight: A simple and robust mechanism coherently directs nanowire growth directions by introducing a local temperature gradient as the local kinetic variable during the conventional vapor–liquid–solid (VLS) growth (see picture, scale bar=200 μm). The nanowires grow straight in the vertical direction, but possess kinks near the catalytic tips.

Regenerated cellulose-silk fibroin blends fibers

“…This process is environmentally benign because the nontoxic NMMO solvent is used and almost all the solvent used is totally recycled [31]. Owing to these advantages, lots of technical developments of Lyocell ® fibre have been reported by many manufacturers [32][33][34][35]. Lyocell ® fibers have proved commercially successful because of better mechanical properties when compared with viscose rayon [36][37][38][39].…”

Vectorial nanowire growth by local kinetic manipulation

“…Here, we demonstrate that this NW growth is spontaneous vectorial [19,20], i.e. both of the NW growth direction and magnitude are proportional to the locally established TG, and facilely controllable and reproducible during the VLS growth in large area over $ 1 cm 2 regardless of shape of a substrate.…”

“…in diameter, surrounded by a uniformly heating zone, with the susceptor underneath the growth substrates that can be cooled by air-circulation [19]. When the furnace was heating the reactor at 650 1C, the temperature near the substrate was stably measured to be 490 1C under air-circulation.…”

“…Using 10% SiH 4 premixed in He of a total pressure of 50 Torr at the 50 sccm the typical NW growth was performed upon the nanoclusters of Au catalysts prepared by deposition of 2 nm thick Au films on 300 nm thick SiO 2 /Si (100) substrate. We estimated the temperature distribution and its gradient in our CVD reactor under the identical experimental condition by computing the steady state thermal conduction, precisely described in our previous work [19].…”

“…local temperatures at the interfaces, can influence the elemental growth behaviors. In this aspect, we have earlier reported a simple and robust integrated growth scheme of SiNWs on the flat Si substrates along the temperature gradient (TG) in the anisothermal condition [19], as depicted in Fig. 1(b).…”