quantum well (rus. квантовая яма) — flat thin layer of semiconductor material (typically between 1 and 10 nm thick) within which the potential energy of an electron is less than outside the layer, therefore the motion of the electron is limited in one dimension. The motion of the electron perpendicular to the quantum well plane is quantised, and its energy can take on only discrete values.

Description

The simplest quantum structure in which electron motion is restricted in one direction is a thin film or a sufficiently thin layer of a semiconductor. It was in thin films of semimetal bismuth and InSb semiconductor that size quantisation effects were first observed. Today quantum structures are manufactured differently. Their production is based on so-called heterostructures, which are obtained by creating semiconductor contacts with different band gaps. A thin layer of a semiconductor with a narrow band gap is placed between two layers of a material with a wider band gap. As a result, the electron is trapped in one dimension, while in the other two dimensions the electron can move freely.

Several sophisticated processes have been developed for manufacturing such structures, but the best results in the formation of quantum heterostructures have been achieved by the method of molecular beam epitaxy. Heterostructures can be grown using different materials, but the best pair for growing quantum wells is gallium arsenide GaAs and the solid solution of AlxGa1-xAs (x = 0.15-0.35).

Today quantum wells are successfully used in the production of lasers.

Illustrations

Schematic representation of a quantum well. The vertical ax
Schematic representation of a quantum well. The vertical axis represents the quantum particle energy, and the horizontal line - its coordinate; a is the width of quantum well; E1,..., En is the set of discrete values of quantum particle's energy.

Authors

  • Saranin Alexander A.
  • Zaitsev Dmitry D.

Source

  1. Demikhovskijj V. J. Quantum well, string, point. What is that? // Sorosovskijj obrazovatel'nyjj zhurnal. 1997. №5. 80–86 pp.

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