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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 a certain crystal momentum (k-vector) in the Brillouin zone. If the k-vectors are different, the ...
The optical band gap (see below) determines what portion of the solar spectrum a photovoltaic cell absorbs. [18] Strictly, a semiconductor will not absorb photons of energy less than the band gap; whereas most of the photons with energies exceeding the band gap will generate heat. Neither of them contribute to the efficiency of a solar cell.
Wide-bandgap semiconductors (also known as WBG semiconductors or WBGSs) are semiconductor materials which have a larger band gap than conventional semiconductors. Conventional semiconductors like silicon and selenium have a bandgap in the range of 0.7 – 1.5 electronvolt (eV), whereas wide-bandgap materials have bandgaps in the range above 2 eV.
In a semiconductor or band insulator, the Fermi level is surrounded by a band gap, referred to as the band gap (to distinguish it from the other band gaps in the band structure). The closest band above the band gap is called the conduction band, and the closest band beneath the band gap is called the valence band.
Tin sulfide (SnS) is a semiconductor with direct optical band gap of 1.3 eV and absorption coefficient above 10 4 cm −1 for photon energies above 1.3 eV. It is a p-type semiconductor whose electrical properties can be tailored by doping and structural modification and has emerged as one of the simple, non-toxic and affordable material for ...
Importantly, an insulator can be made to conduct by increasing its temperature: heating provides energy to promote some electrons across the band gap, inducing partially filled states in both the band of states beneath the band gap (valence band) and the band of states above the band gap (conduction band). An (intrinsic) semiconductor has a ...
Gallium nitride (Ga N) is a binary III/V direct bandgap semiconductor commonly used in blue light-emitting diodes since the 1990s. The compound is a very hard material that has a Wurtzite crystal structure. Its wide band gap of 3.4 eV affords it special properties for applications in optoelectronics, [9] [10] [11] high-power
The three types of semiconductor heterojunctions organized by band alignment. Band diagram for straddling gap, n-n semiconductor heterojunction at equilibrium.. The behaviour of a semiconductor junction depends crucially on the alignment of the energy bands at the interface.