Electronics - Quantum Dots

Quantum Dots are particular type of crystal which is emerged by nanotechnology and will obsolete or expel the present semiconductor technology. This nanocrystal has the property of ‘tunable’ emission and absorption spectra and can emit all the frequencies in the visible region and infra-red.

Special class of nanocrystal semiconductors composed of II–VI, III-V and IV-VI combination of materials are used for quantum dots. The main advantages of this crystal is that its size is very small and its band gap can be tuned or controlled by its manufacturing technique. It will have the diameter of the order of a few nanometres(2nm-10nm).

Since the size is so small its energy gap is specified in ‘Excitation Bohr Radius’. It is the physical distance that must be taken into consideration when the size of the dot is compared with. This parameter is different for different materials.
In the case of bulk semiconductors, its size is not comparable with Bohr radius. Due to this, the electron energy level of these crystals should be treated as discrete (not-continuous) i.e. finite separation between the energy levels. Under this condition, semiconductor behaves entirely in different way than the bulk semiconductor and it is called quantum dot.