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In a semiconductor, the energy gap between valence band and conduction band is about ___________.

Last updated date: 25th Jul 2024
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Hint:Semiconductors are materials with conductivity intermediate between conductors (typically metals) and non-conductors or insulators (such as most ceramics). Semiconductors can be pure elements like silicon or germanium, or they can be additives like gallium arsenide or cadmium selenide.

Complete answer:
A band gap, also known as an energy gap in solid-state physics, is an energy spectrum in a solid where no electronic states can occur. The band gap is the energy difference (in electron volts) between the top of the valence band and the bottom of the conduction band of insulators and semiconductors in diagrams of the electrical band configuration of solids.

That is the amount of energy needed to convert a valence electron bound to an atom into a conduction electron, which is free to travel inside the crystal lattice and act as a charge carrier to conduct electric current. In chemistry, it is closely similar to the HOMO/LUMO gap.Electrons cannot pass in a solid if the valence band is fully full and the conduction band is completely empty; however, if any electrons migrate from the valence to the conduction band, current will flow (see carrier generation and recombination).

As a result, the band gap is an important element in deciding a solid's electrical conductivity. Insulators have big band gaps, semiconductors have smaller band gaps, and conductors have very small band gaps or none at all when the valence and conduction bands overlap.Between the valence band and the conduction band in a semiconductor, there is a slight energy difference of around 1 eV.

The forbidden energy gap, also known as band gap, in materials corresponds to the energy difference (eV) between the top of the valence band and the bottom of the conduction band. The electron transfer from the valence band to the conduction band causes current to pass through the materials.Since semiconductors' electrical conductivity lies between conductors and insulators, a minimal but non-zero bandgap (1eV) exists in semiconductors.For example, the bandgaps of silicon and germanium are 1.11eV and 0.67eV, respectively.

Note:A semiconductor is a substance with a non-zero band gap that acts as an insulator at absolute zero but enables thermal excitation of electrons into its conduction band at temperatures below its melting point. A substance with a big band difference, on the other hand, is an insulator. Since the valence and conduction bands in conductors may overlap, they may not have a band difference.