A semiconductor is a material with an intermediate-sized, non-zero band gap that behaves as an insulator at T=0K, but allows thermal excitation of electrons into its conduction band at temperatures that are below its melting point.

The band gap is a very important property of a semiconductor because it determines its color and conductivity. Many of the applications of semiconductors are related to band gaps: Narrow gap materials (Hg x Cd 1 - x Te, VO 2 , InSb, Bi 2 Te 3 ) are used as infrared photodetectors and thermoelectrics (which convert heat to electricity).

In semiconductors, the band gap of a semiconductor can be of two basic types, a direct band gap or an indirect band gap. The minimal-energy state in the conduction band and the maximal-energy state in the valence band are each characterized by …

Data from Kittel, C., Introduction to Solid State Physics, 6th Ed., New York:John Wiley, 1986, p. 185.

2019年6月11日 · The bandgap, or band gap, describes the space in all solids where no electrons go, between those two bands, valence and conduction. The gap, also known as an energy gap, varies by material from no bandgap to wide bandgap.

A low band gap implies higher intrinsic conduction, and a high band gap implies a larger possible photon energy associated with a transition across the gap in light emitting diodes. Band gaps in electron volts are given for a few semiconductor materials in the table below.

According to the band theory of solids, which is an outcome of quantum mechanics, semiconductors possess a band gap, i.e., there is a range of forbidden energy values for the electrons and holes.

2010年7月23日 · When electricity passes through a semiconductor, it can emit a photon, whose color is determined by the material’s bandgap. That’s the basis for light-emitting diodes, which are increasingly being used for displays and computer screens, and are seen as the ultimate low-power light bulbs.

Therefore, semiconductors (at least those with a narrow band gap) appear opaque and can transmit only infrared light – and that with a rather high refractive index. The details, however, substantially depend on whether we have a direct or indirect band gap – see below.

Semiconductors are classified by the fully occupied valence band and unoccupied conduction band. With the small band gap in between these two bands, it takes a certain amount of energy to excite the electrons from the valence to conduction band.