Free-standing SiGe-based nanopipelines on Si (001) substrates

Thin solid films form nanopipelines if the films are released from a substrate and put back onto their own surface. We give a detailed description of free-standing SiGe-based nanopipelines created on Si (001) substrates. The initial layer sequence is grown by molecular beam epitaxy and comprises SiGe-based epitaxial layers grown on a Ge sacrificial layer. After selectively etching away the Ge sacrificial layer, SiGe nanopipelines have formed on the surface. Nanopipelines as long as 20 mum with diameters ranging from 50 to 530 nm are fabricated. We show that SiGe nanopipelines perform multiple revolutions if selective etching is carried out long enough. Adding carbon to Si epitaxial layers is proposed to extend the design freedom of Si-based nanopipelines and nanotubes. (C) 2001 American Institute of Physics.