Free-standing Si/SiGe micro- and nano-objects

Free-standing SiGe/Si microtubes, microneedles, helical coils, bridges and submicron vertical rings have been fabricated from elastically strained SiGe/Si heterostructures grown by ultra-high vacuum chemical vapor deposition. Three-dimensional micro- and nano-objects have been formed by self-scrolling after electron beam lithography, reactive ion etching and wet selective etching. Vertical rings with very smooth sidewalls may have applications in hot embossing lithography as well as in microelectronics and micromechanics. By adjusting the SiGe/Si bilayer thickness or Ge concentration, the diameter of tube or ring could be decreased into the nanometer scale.