quantum dot
abbr.,
QD; ND
otherwise
nano-dot
(rus. квантовая точка abbr., КТ)
—
particle of a material, whose size is close to the wavelength of an electron in such material (usually 1-10 nm); the electron potential energy in such particle is lower than outside of it, therefore motion of the electron is limited in all three dimensions.
Description
Examples of quantum dots include:
- semiconductor heterostructures with spatial restriction of charge carriers in three dimensions that represent the extreme case of size quantisation;
- isolated metal or semiconductor nanoparticles/nanobeads, whose diameter satisfies the conditions of size quantisation, small (1-10 nm) molecules and molecular clusters;
-Fine particles of semiconductors, either colloidal or deposited on a porous carrier, 1-30 nm in diameter.
The electronic spectrum of an ideal quantum dot is a set of discrete levels, separated by regions of forbidden states; it formally corresponds to an electronic spectrum of a single atom. However, the real quantum dot can consist of hundreds of thousands of atoms. The minimum and maximum sizes of quantum dots depend on their substance; for example, in the system InAs-AlGaAs the minimum size of quantum dots is 4 nm and their maximum size shall not exceed 30 nm.
- semiconductor heterostructures with spatial restriction of charge carriers in three dimensions that represent the extreme case of size quantisation;
- isolated metal or semiconductor nanoparticles/nanobeads, whose diameter satisfies the conditions of size quantisation, small (1-10 nm) molecules and molecular clusters;
-Fine particles of semiconductors, either colloidal or deposited on a porous carrier, 1-30 nm in diameter.
The electronic spectrum of an ideal quantum dot is a set of discrete levels, separated by regions of forbidden states; it formally corresponds to an electronic spectrum of a single atom. However, the real quantum dot can consist of hundreds of thousands of atoms. The minimum and maximum sizes of quantum dots depend on their substance; for example, in the system InAs-AlGaAs the minimum size of quantum dots is 4 nm and their maximum size shall not exceed 30 nm.
Illustrations
|
A section of Si(100) surface with a dimple ~100 nm in diameter and 16 nm deep having a quantum dot at the bottom represented by a thin layer of Ge atoms. On the right - cross profile of the dimple with the quantum dot sized ~30 nm in diameter and 1.5 nm in height. |
Authors
- Gusev Alexander I.
- Tolkachev Nikolay N.
Sources
- Gusev A. I. Nanomaterials, Nanostructures, and Nanotechnologies (in Russian) // Fizmatlit, Moscow (2007) - 416 pp.
- Gusev A. I. Rempel A.A. Nanocrystalline Materials. — Cambridge: Cambridge International Science Publishing, 2004. — 351 p.