Quantum well

Schematic of a semiconductor heterostructure quantum well. The shaded (well) region should be narrow enough (L should be typically less than 30 nm) for quantum effects to be manifested, in particular, for a discrete energy spectrum of charge carriers to be sufficiently resolved at room temperature.

A quantum well is a potential well wherein the energy spectrum of charge carriers is discrete.

As opposed to a bulk region, wherein the carriers are free to move in three spatial directions, their motion is free only in two (planar) directions in a quantum well. The quantum size effects take place when the size of a region in at least one of the directions (the direction of growth in the case of semiconductor heterostructure quantum wells - the transverse direction) becomes comparable to the de Broglie wavelength of the carriers (electrons and holes in a semiconductor), resulting in a discrete energy spectrum for them.

Semiconductor quantum wells can be realized in double heterostructures. The double heterostructure concept was proposed in 1963 independently by Herbert Kroemer and by Zhores Alferov and Rudolf Kazarinov.

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