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.


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.


A section of Si(100) surface with a dimple ~100 nm in diameter and 16 nm deep having a quantum
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.


  • Gusev Alexander I.
  • Tolkachev Nikolay N.


  1. Gusev A. I. Nanomaterials, Nanostructures, and Nanotechnologies (in Russian) // Fizmatlit, Moscow (2007) - 416 pp.
  2. Gusev A. I. Rempel A.A. Nanocrystalline Materials. — Cambridge: Cambridge International Science Publishing, 2004. — 351 p.

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