Optically-tuned nanotube and nanowire growth

Carbon nanotubes (CNTs) and Si nanowires (SiNWs) are two classes of nano-materials expected to play a major role in nanoscience and -technology. Their extremely well defined structures make them perfectly suited for fundamental studies of nanoscale physics. Additionally, their unique mechanical, electrical and optical properties make both material systems very promising for future applications. In this context, controlled fabrication and the precise alignment and orientation of CNTs and SiNWs on suitable substrates still pose major problems. Optically controlled growth may offer a solution and will be investigated in the proposed project. Metal nanoparticles will serve as nanocatalysts for the growth. Heating the metallic catalysts directly by selective plasmonic absorption of light with tuneable wavelength will enable spatial and temporal controlled growth, not possible with standard techniques, where the entire substrate is heated. In addition, the laser parameters (polarization, wavelength, power, etc.), offer a completely new parameter space to control the growth. The main aim of the proposed project is to investigate the possibilities for controlling the growth direction and, in the case of CNTs, their chirality.