Real-time formation, accurate positioning, and fluid filling of single rolled-up nanotubes

We apply real-time video microscopy to monitor the formation of rolled-up InAs/GaAs tubes in great detail. The roll-up process is highly nonlinear at the beginning, linear at an intermediate stage, and ceases for long etching times. This self-limitation effect allows precise positioning of the tubes on a substrate surface. We investigate the formation of rolled-up nanotubes (RUNTs) on lithographically patterned substrates as a function of sacrificial layer thickness and tube diameter, and our results are well-described by a simple diffusion model. We fill well-positioned RUNTs of well-defined lengths with dye liquid and we observe strong fluorescence signal of these structures in the red spectral range. (C) 2004 American Institute of Physics.