Quantum Electronics

Question 021-08: What are Quantum Dots & Wires? Which phenomenon leads to the study of Quantum Dots & Wires? How the problems are solved using Quantum Dots & Wires in comparison with conventional device? 

Answer 021-08: When an electron is confined spatially on a scale that is comparable to its wavelength, then quantum mechanics controls its properties.  This is the reason for energy level in atoms and molecules.  It is also possible to artificially confine electrons by producing a very small "dot" of a semiconductor.  The energy levels for the electron can then be engineered.  For example, the wavelengths (i.e. colors) of light that are absorbed can be engineered by the size and shape of the quantum dot. Quantum dots of this kind have applications in medical diagnostics (for optical labeling). They are also being explored as a possible avenue for increasing the efficiency of solar cells and of thermoelectric materials.

Quantum wires are similarly-engineered quantum structures. Instead of confining electrons in all three dimensions as in a quantum dot, electrons are confined in two dimensions but are free to move in a third dimension. This produces a wire in which electrons behave as one-dimensional particles.  Again, the quantum confinement changes the electronic properties (e.g. the density-of-states) in ways that may be beneficial to transistors performance, thermoelectrics, and possibly other applications.