Quantum Confinement

QUANTUM CONFINEMENT

Definition

The effect achieved by reducing the volume of a solid so that the energy levels within it becomes discrete is called quantum cofinement.

When we decrease the volume of a solid to such an extent that the energy levels inside become discrete, we have acheived quantum cofinement.

By doing so, small 'droplets' of isolated electrons are formed. Hence, it is possible for us to count few electrons.

Explanation

The quantum confinement effect is observed when the size of the particle is too small to be comparable to the wavelength of the electron.

To know this effect we break the words like quantum and confinement. The word confinement means to confine the motion of randomly moving electron to restrict its motion in specific energy levels (discreteness) and quantum reflects the atomic dimension of particles.

Fig. 5.2 Quantum confinement is responsible for the increase of energy difference between energy states and band gap

If we decrease the size of the particle to the nano size, the decrease in confining size creates the energy levels discrete. The formation of discrete energy levels increases or widens up the band gap and finally the band gap energy also increases as shown in Fig. 5.2.

Due to this, there is a significant change in the electronic and optical materials of nano-dimensions as compared to the bulk materials.

Since, the band gap and wavelength are inversely related to each other the wavelength decreases with decrease in size and the proof is the emission of blue radiation.