Nanostructures: Superlattices, Quantum Wires, and Quantum Dots
The advanced microfabrication techniques can produce objects which are sufficiently small, that new quantum effects appear. After discussing superlattices and Bloch oscillations, we turn to the Landauer transmission channels and the quantized conductance of quantum wires. The fullerenes are carbon molecules consisting of different distinct numbers of carbon atoms. Their outgrowth in form of carbon nanotubes represents a promising structure for molecular electronics. Conducting layers of graphene with a thickness of only a single carbon atom display a fascinating electronic band structure, where the concentration of charge carriers can be varied strongly by means of an attached gate electrode. Quantum dots find increasing use in optoelectronics. Topological insulators show surprising current-carrying edge or surface states. The topological properties of the electronic band structure and possible contact points between the valence band and the conduction band and band crossings turned into important points of modern developments.