Semiconductor tubes, rods and rings of nanometer and micrometer dimension

Strained semiconductor bilayers are released from their substrate and formed into free-standing tubes, rods and rings on semiconductor surfaces. We present nanotubes based on the InGaAs/GaAs, SiGe/Si, and InGaP material system. The inner diameters of our tubes vary from 15 to View the MathML source. We present rolled-up nanotubes, which have performed up to 30 revolutions. The wall thickness of the nanotubes depends on the number of rotations. As a consequence, the inner to outer diameter ratio can be tuned over a wide range, i.e. from 1 to 0.125. In the latter case the nanotubes become nanorods. Strained layers are bent in two directions, vertical and horizontal. The result are ultra-thin and ring-like vertical free-standing membranes. The wide range of possible materials and structural properties make these tubes and rings interesting candidates for fundamental investigations as well as for applications.