Precise semiconductor nanotubes and nanoshells fabricated on (110) and (111) Si and GaAs

In our previous works, we showed that ultrathin epitaxial heterofilms (down to two monolayers for the case of InGaAs/GaAs) can be controllably detatched from substrates and rolled, under the action of internal stresses, into various cylindrical micro- and nanoshells (tubes, scrolls, rings, spirals, etc.). The present review outlines the cornerstone stages in the development of this fabrication technology for semiconductor and metal nanoobjects, including: (1) directional rolling of films yielding 3D micro- and nanoshells of various shapes; (2) assembling of micro- and nanoshells in more complex architectures; (3) super-critical drying of nanoshells, and (4) formation of nanoshells whose sizes can be precisely controlled in three dimensions. With this technology new possibilities that open up for the use of strained films, selectively, grown on uncommonly used (I 10) and (I 1 1) surfaces, are presented. The role of mechanical anisotropy in the formation of the 3D nanoshells and the electrical and mechanical properties of formed nanotubes are discussed. (C) 2004 Elsevier B.V. All rights reserved.