Control challenges in semiconductor nanostructure devices

A superlattice is an artificial crystal made out by repeating periodically a basic unit comprising layers of two or more semiconductors. Superlattice based devices include infrared detectors, quantum cascade lasers and fast oscillators. A simple device consists of a finite superlattice with attached contacts and connected to an external circuit. If it is connected to a current source, the electric field profile inside the superlattice may be a wave front, which is possible to leave stationary or to move upstream or downstream of the electron flow depending on the value of the current. Under dc voltage bias, it is possible to attain stationary states or self-sustained oscillations of the current by controlling the voltage.