Electron Confinement (Quantum Confinement)

Electron confinement or quantum confinement is another process that occur in nanoparticles

What is Quantum Confinement?

Quantum confinement describes how the electronic and optical properties change when the material size is at the nanoscale.

One of the most direct effects of reducing the size of materials to nanoscale is the appearance Of Quantisation effects due to the confinement of the movement of electrons. This leads to the discrete energy levels depending on the size of the structure. Control over dimensions as well as the composition of structures thus makes it possible to tailor material properties to specific application quantization effects play a major role in semiconductor electronics and optoelectronic components

The quantization confinement can be observed only when the diameter of the material is of the same magnitude as the wavelength of the electron wave function.

Quantum confinement effects describe elect•ons in terms of energy levels, the potential well, valence band, conduction band, and energy band gap. The electrons in a bulk material can be described as by energy bands or electron energy levels. These energy levels are described as continuous, because of the difference in energy is negligible. In this case, the electrons behave as if it were free in which case the confinement dimensions are large compared to the wavelength of the particle. At this, stage the band gap remains at its original energy due to a continuous energy state.

However, when the material size is decreased towards nanoscale, the confinement dimensions naturally decrease. In other words, the energy spectrum becomes discrete measured as quanta rather than continuous as in bulk materials. This situation of discrete energy levels is called quantum confinement.

Thus to conclude; in nanomaterials, the electrons are confined in space rather than free to move the case of bulk materials.

Nanoscale quantum confinement can be 0D, ID or 2D.

0D confinement is found in quantum dots. In quantum dots, the electrons have no freedom in Any dimension and the electrons are said to be localized at a point implying that; a change in any of the directions changes the properties.

1D confinement is found in nanowires. Electron confinement in one direction results in a quantum wire, leaving the electrons free to move only along one direction.

2D confinement is found in quantum wells. In the quantum well, the electrons are confined within a two-dimensional area.

Note:

In 1 D and 2D nanomaterials, the electron confinement and delocalization coexist but in

3D nanomaterials, the electrons are fully delocalized.

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