Mercury telluride (HgTe) is a binary chemical compound of mercury and

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 occasionall ...

. It is a

semi-metal A semimetal is a material with a very small overlap between the bottom of the conduction band and the top of the valence band. According to electronic band theory, solids can be classified as insulators, semiconductors, semimetals, or metals. ...

related to the II-VI group of

semiconductor A semiconductor is a material which has an electrical conductivity value falling between that of a conductor, such as copper, and an insulator, such as glass. Its resistivity falls as its temperature rises; metals behave in the opposite way. ...

materials. Alternative names are mercuric telluride and mercury(II) telluride. HgTe occurs in nature as the mineral form

coloradoite Coloradoite, also known as mercury telluride (HgTe), is a rare telluride ore associated with metallic deposit (especially gold and silver). Gold usually occurs within tellurides, such as coloradoite, as a high-finess native metal. The quest for ...

Physical properties

All properties are at standard temperature and pressure unless stated otherwise. The lattice parameter is about 0.646 nm in the cubic crystalline form. The bulk modulus is about 42.1 GPa. The thermal expansion coefficient is about 5.2×10⁻⁶/K. Static dielectric constant 20.8, dynamic dielectric constant 15.1.

Thermal conductivity The thermal conductivity of a material is a measure of its ability to conduct heat. It is commonly denoted by k, \lambda, or \kappa. Heat transfer occurs at a lower rate in materials of low thermal conductivity than in materials of high thermal ...

is low at 2.7 W·m²/(m·K). HgTe bonds are weak leading to low hardness values. Hardness 2.7×10⁷ kg/m².

Doping

N-type doping can be achieved with elements such as boron,

aluminium Aluminium (aluminum in American and Canadian English) is a chemical element with the symbol Al and atomic number 13. Aluminium has a density lower than those of other common metals, at approximately one third that of steel. I ...

, gallium, or

indium Indium is a chemical element with the symbol In and atomic number 49. Indium is the softest metal that is not an alkali metal. It is a silvery-white metal that resembles tin in appearance. It is a post-transition metal that makes up 0.21 parts ...

. Iodine and iron will also dope n-type. HgTe is naturally p-type due to mercury vacancies. P-type doping is also achieved by introducing zinc, copper, silver, or gold.

Topological insulation

Mercury telluride was the first

topological insulator A topological insulator is a material whose interior behaves as an electrical insulator while its surface behaves as an electrical conductor, meaning that electrons can only move along the surface of the material. A topological insulator is an ...

discovered, in 2007. Topological insulators cannot support an electric current in the bulk, but electronic states confined to the surface can serve as charge carriers.

Chemistry

HgTe bonds are weak. Their

enthalpy of formation Enthalpy , a property of a thermodynamic system, is the sum of the system's internal energy and the product of its pressure and volume. It is a state function used in many measurements in chemical, biological, and physical systems at a constant p ...

, around −32kJ/mol, is less than a third of the value for the related compound cadmium telluride. HgTe is easily etched by acids, such as

hydrobromic acid Hydrobromic acid is a strong acid formed by dissolving the diatomic molecule hydrogen bromide (HBr) in water. "Constant boiling" hydrobromic acid is an aqueous solution that distills at and contains 47.6% HBr by mass, which is 8.77 mol/L. ...

Growth

Bulk growth is from a mercury and tellurium melt in the presence of a high mercury vapour pressure. HgTe can also be grown epitaxially, for example, by sputtering or by

metalorganic vapour phase epitaxy 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. ...

. Nanoparticles of mercury telluride can be obtained via cation exchange from cadmium telluride nanoplatelets.

References

External links

Thermophysical properties database
at Germany's Chemistry Information Centre, Berlin {{Tellurides Mercury(II) compounds Tellurides II-VI semiconductors Zincblende crystal structure