Zinc selenide (ZnSe) is a light-yellow, solid compound comprising

zinc Zinc is a chemical element with the symbol Zn and atomic number 30. Zinc is a slightly brittle metal at room temperature and has a shiny-greyish appearance when oxidation is removed. It is the first element in group 12 (IIB) of the periodic t ...

(Zn) and

selenium Selenium is a chemical element with the symbol Se and atomic number 34. It is a nonmetal (more rarely considered a metalloid) with properties that are intermediate between the elements above and below in the periodic table, sulfur and telluriu ...

(Se). It is an

intrinsic semiconductor An intrinsic (pure) semiconductor, also called an undoped semiconductor or i-type semiconductor, is a pure semiconductor without any significant dopant species present. The number of charge carriers is therefore determined by the properties of the ...

with a

band gap In solid-state physics, a band gap, also called an energy gap, is an energy range in a solid where no electronic states can exist. In graphs of the electronic band structure of solids, the band gap generally refers to the energy difference ( ...

of about 2.70 eV at . ZnSe rarely occurs in nature, and is found in the

mineral In geology and mineralogy, a mineral or mineral species is, broadly speaking, a solid chemical compound with a fairly well-defined chemical composition and a specific crystal structure that occurs naturally in pure form.John P. Rafferty, ed. ...

that was named after

Hans Stille Hans Wilhelm Stille (8 October 1876 – 26 December 1966) was an influential German geologist working primarily on tectonics and the collation of tectonic events during the Phanerozoic. Stille adhered to the contracting Earth hypothesis and toget ...

called "

stilleite Stilleite is a selenide mineral, zinc selenide, with the formula Zn Se. It has been found only as microscopic gray crystals occurring as inclusions in linnaeite associated with other selenide and sulfides. It was originally discovered in Katan ...

Properties

ZnSe can be made in both hexagonal ( wurtzite) and cubic (

zincblende Sphalerite (sometimes spelled sphaelerite) is a sulfide mineral with the chemical formula . It is the most important ore of zinc. Sphalerite is found in a variety of deposit types, but it is primarily in sedimentary exhalative, Mississippi-Va ...

) crystal structure. It is a wide-bandgap semiconductor of the II-VI semiconductor group (since

and

belong to the 12th and 16th groups of the

periodic table The periodic table, also known as the periodic table of the (chemical) elements, is a rows and columns arrangement of the chemical elements. It is widely used in chemistry, physics, and other sciences, and is generally seen as an icon of ...

, respectively). The material can be doped n-type

doping Doping may refer to: * Doping, adding a dopant to something * Doping (semiconductor), intentionally introducing impurities into an extremely pure semiconductor to change its electrical properties * Aircraft dope, a lacquer that is applied to fabr ...

with, for instance, halogen elements. P-type doping is more difficult, but can be achieved by introducing

gallium Gallium is a chemical element with the symbol Ga and atomic number 31. Discovered by French chemist Paul-Émile Lecoq de Boisbaudran in 1875, Gallium is in group 13 of the periodic table and is similar to the other metals of the group ( alum ...

Applications

* ZnSe is used to form II-VI

light-emitting diode A light-emitting diode (LED) is a semiconductor device that emits light when current flows through it. Electrons in the semiconductor recombine with electron holes, releasing energy in the form of photons. The color of the light ( ...

s and

diode laser The laser diode chip removed and placed on the eye of a needle for scale A laser diode (LD, also injection laser diode or ILD, or diode laser) is a semiconductor device similar to a light-emitting diode in which a diode pumped directly with e ...

s. It emits blue light. * ZnSe doped with

chromium Chromium is a chemical element with the symbol Cr and atomic number 24. It is the first element in group 6. It is a steely-grey, lustrous, hard, and brittle transition metal. Chromium metal is valued for its high corrosion resistance and h ...

(ZnSe:Cr) has been used as an

infrared Infrared (IR), sometimes called infrared light, is electromagnetic radiation (EMR) with wavelengths longer than those of visible light. It is therefore invisible to the human eye. IR is generally understood to encompass wavelengths from aroun ...

laser gain medium The active laser medium (also called gain medium or lasing medium) is the source of optical gain within a laser. The gain results from the stimulated emission of photons through electronic or molecular transitions to a lower energy state from a h ...

emitting at about 2.4

μm The micrometre ( international spelling as used by the International Bureau of Weights and Measures; SI symbol: μm) or micrometer (American spelling), also commonly known as a micron, is a unit of length in the International System of Unit ...

. * It is used as an infrared optical material with a remarkably wide transmission wavelength range (0.45 μm to 21.5 μmhttps://web.archive.org/web/20190422005411/http://www.kayelaby.npl.co.uk/general_physics/2_5/2_5_8.html Kaye and Laby online at NPL via archive.org). The

refractive index In optics, the refractive index (or refraction index) of an optical medium is a dimensionless number that gives the indication of the light bending ability of that medium. The refractive index determines how much the path of light is bent, o ...

is about 2.67 at 550 nm (green), and about 2.40 at 10.6 μm ( LWIR). Similar to

zinc sulfide Zinc sulfide (or zinc sulphide) is an inorganic compound with the chemical formula of ZnS. This is the main form of zinc found in nature, where it mainly occurs as the mineral sphalerite. Although this mineral is usually black because of various i ...

, ZnSe is produced as

microcrystalline A microcrystalline material is a crystallized substance or rock that contains small crystals visible only through microscopic examination. There is little agreement on the range of crystal sizes that should be regarded as microcrystalline, but th ...

sheets by synthesis from

hydrogen selenide Hydrogen selenide is an inorganic compound with the formula H2Se. This hydrogen chalcogenide is the simplest and most commonly encountered hydride of selenium. H2Se is a colorless, flammable gas under standard conditions. It is the most toxic sele ...

gas and

vapour. Another method of producing is a growth from melt under excessive pressure of inert gas ( Ar usually). When free of absorption and inclusions it is ideally suited for CO₂ laser optics at 10.6 μm wavelength. It is thus a very important IR material. In daily life, it can be found as the entrance optic in the new range of "in-ear" clinical thermometers, seen as a small yellow window. Zinc selenide can slowly react with atmospheric moisture if poorly polished, but this is not generally a serious problem. Except where optics are used in

spectroscopy Spectroscopy is the field of study that measures and interprets the electromagnetic spectra that result from the interaction between electromagnetic radiation and matter as a function of the wavelength or frequency of the radiation. Matter ...

or at the

Brewster angle Brewster's angle (also known as the polarization angle) is an angle of incidence at which light with a particular polarization is perfectly transmitted through a transparent dielectric surface, with ''no reflection''. When ''unpolarized'' ligh ...

, antireflection or beamsplitting

optical coating An optical coating is one or more thin layers of material deposited on an optical component such as a lens, prism or mirror, which alters the way in which the optic reflects and transmits light. These coatings have become a key technology in t ...

s are generally employed. * ZnSe activated with

tellurium Tellurium is a chemical element with the symbol Te and atomic number 52. It is a brittle, mildly toxic, rare, silver-white metalloid. Tellurium is chemically related to selenium and sulfur, all three of which are chalcogens. It is occasionally fo ...

(ZnSe(Te)) is a

scintillator A scintillator is a material that exhibits scintillation, the property of luminescence, when excited by ionizing radiation. Luminescent materials, when struck by an incoming particle, absorb its energy and scintillate (i.e. re-emit the absorbe ...

with emission peak at 640 nm, suitable for matching with photodiodes. It is used in

x-ray X-rays (or rarely, ''X-radiation'') are a form of high-energy electromagnetic radiation. In many languages, it is referred to as Röntgen radiation, after the German scientist Wilhelm Conrad Röntgen, who discovered it in 1895 and named it ' ...

and

gamma ray A gamma ray, also known as gamma radiation (symbol γ or \gamma), is a penetrating form of electromagnetic radiation arising from the radioactive decay of atomic nucleus, atomic nuclei. It consists of the shortest wavelength electromagnetic wav ...

detectors. ZnSe scintillators are significantly different from the ZnS ones.

Chemistry

ZnSe is insoluble in water, but reacts with acids to form toxic

gas. It can be deposited as a thin film by

chemical vapour deposition Chemical vapor deposition (CVD) is a vacuum deposition method used to produce high quality, and high-performance, solid materials. The process is often used in the semiconductor industry to produce thin films. In typical CVD, the wafer (substra ...

techniques including

MOVPE Metalorganic vapour-phase epitaxy (MOVPE), also known as organometallic vapour-phase epitaxy (OMVPE) or metalorganic chemical vapour deposition (MOCVD), is a chemical vapour deposition method used to produce single- or polycrystalline thin films. ...

and vacuum evaporation.

References

External links

II-VI - INFRARED
optical data & more
University of Reading, Infrared Multilayer Laboratory
optical data {{Selenides

selenide A selenide is a chemical compound containing a selenium anion with oxidation number of −2 (Se2−), much as sulfur does in a sulfide. The chemistry of the selenides and sulfides is similar. Similar to sulfide, in aqueous solution, the selenide ion ...

Selenides II-VI semiconductors Optical materials Phosphors and scintillators Laser gain media Zincblende crystal structure Wurtzite structure type