Search results
Results from the WOW.Com Content Network
Zinc selenide is the inorganic compound with the formula ZnSe. It is a lemon-yellow solid although most samples have a duller color due to the effects of oxidation. It is an intrinsic semiconductor with a band gap of about 2.70 eV at 25 °C (77 °F), equivalent to a wavelength of 459 nm.
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.
Ternary compositions allow adjusting the band gap within the range of the involved binary compounds; however, in case of combination of direct and indirect band gap materials there is a ratio where indirect band gap prevails, limiting the range usable for optoelectronics; e.g. AlGaAs LEDs are limited to 660 nm by this. Lattice constants of the ...
Tensions and impurities due to low crystal quality result in low optoelectronic properties. One example of the basic possibilities achievable with three different compounds is shown in the diagram with zinc oxide (ZnO), cadmium oxide (CdO) and magnesium oxide (MgO). Basically it is possible to gain any band gap between those of the three materials.
Copper zinc tin sulfide (CZTS) is a quaternary semiconducting compound which has received increasing interest since the late 2000s for applications in thin film solar cells. The class of related materials includes other I 2 -II-IV-VI 4 such as copper zinc tin selenide (CZTSe) and the sulfur-selenium alloy CZTSSe.
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 ...
Get AOL Mail for FREE! Manage your email like never before with travel, photo & document views. Personalize your inbox with themes & tabs. You've Got Mail!
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.