Meandering growth of in-plane silicon nanowire springs

Despite the fundamental difference in material systems and temporal evolution, self-oscillating growth of silicon nanowires (SiNWs), led by metal droplets, resembles very much natural river meanders in terms of their sinuosity, fractal dimensions, and scaling law. Both of them are driven by the release of higher potential energy stored in the disorder hydrogenated amorphous Si (a-Si:H) matrix or at highlands, tailored by a streamwise flow mechanism and subject to an erodible boundary constraint imposed by the a-Si:H thin film or the soil banks, respectively. Under specific conditions, the cross-droplet/stream velocity difference can be magnified, during the in-plane growth of SiNWs, to stimulate regular swaggering dynamics that produce continuous and smooth SiNW meanders. This interesting phenomenon indicates a rather simple and highly efficient strategy to shape complex elastic channels with only a few control parameters. A kinetic model has been established to explain the underlying mechanism of the self-oscillating meandering growth, which has unique potential to transform rigid SiNW channels into elastic forms for flexible or stretchable electronic applications.