Mercury telluride is a binary chemical compound of mercury

Mercury (element)

Mercury is a chemical element with the symbol Hg and atomic number 80. It is also known as quicksilver or hydrargyrum...

 and tellurium. It is a semi-metal related to the II-VI group of semiconductor

Semiconductor

A semiconductor is a material with electrical conductivity due to electron flow intermediate in magnitude between that of a conductor and an insulator. This means a conductivity roughly in the range of 103 to 10−8 siemens per centimeter...

 materials. Alternative names are mercuric telluride and mercury(II) telluride.

HgTe occurs in nature as the mineral form coloradoite

Coloradoite

Coloradoite, also known as mercury telluride , is a rare telluride ore associated with metallic deposit . Gold usually occurs within tellurides as a high finess native-metal ....

.

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 is low at 2.7W·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

Boron

Boron is the chemical element with atomic number 5 and the chemical symbol B. Boron is a metalloid. Because boron is not produced by stellar nucleosynthesis, it is a low-abundance element in both the solar system and the Earth's crust. However, boron is concentrated on Earth by the...

, aluminium

Aluminium

Aluminium or aluminum is a silvery white member of the boron group of chemical elements. It has the symbol Al, and its atomic number is 13. It is not soluble in water under normal circumstances....

, gallium

Gallium

Gallium is a chemical element that has the symbol Ga and atomic number 31. Elemental gallium does not occur in nature, but as the gallium salt in trace amounts in bauxite and zinc ores. A soft silvery metallic poor metal, elemental gallium is a brittle solid at low temperatures. As it liquefies...

, or indium

Indium

Indium is a chemical element with the symbol In and atomic number 49. This rare, very soft, malleable and easily fusible post-transition metal is chemically similar to gallium and thallium, and shows the intermediate properties between these two...

. 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.

Chemistry

HgTe bonds are weak. Their enthalpy of formation, 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

Hydrobromic acid is a strong acid formed by dissolving the diatomic molecule hydrogen bromide in water. "Constant boiling" hydrobromic acid is an aqueous solution that distills at 124.3 °C and contains 47.6% HBr by weight, which is 8.89 mol/L. Hydrobromic acid has a pKa of −9, making it a...

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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

Metalorganic vapour phase epitaxy , also known as organometallic vapour phase epitaxy or metalorganic chemical vapour deposition , is a chemical vapour deposition method of epitaxial growth of materials, especially compound semiconductors, from the surface reaction of organic compounds or...

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Unique physical properties

Recently it was shown both theoretically and experimentally, that mercury-telluride quantum well shows a unique new state of matter—the "topological insulator

Topological insulator

A topological insulator is a material that behaves as an insulator in its interior or bulk while permitting the movement of charges on its surface....

". In this phase, while the bulk is an insulator, current can be carried by electronic states confined close to the sample edges. Unlike the quantum hall effect, here no magnetic field is required to create this unique behavior. In addition, oppositely directed edge states carry opposite spin projections.

External links

• Thermophysical properties database at Germany's Chemistry Information Centre, Berlin