Mercury telluride

Mercury telluride
Systematic name Mercury telluride
Other names Mercuric telluride, mercury(II) telluride
Identifiers
CAS number	12068-90-5 Y
Properties
Molecular formula	HgTe
Molar mass	329.18 g/mol
Appearance	near black cubic crystals
Density	8.1 g/cm3
Structure
Crystal structure	Sphalerite, cF8
Space group	F-43m, No. 216
Y telluride (verify) (what is: Y/N?) Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

Mercury telluride (HgTe) is a binary chemical compound of mercury and tellurium. It is a semi-metal related to the II-VI group of semiconductor materials. Alternative names are mercuric telluride and mercury(II) telluride.

HgTe occurs in nature as the mineral form coloradoite.

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, aluminium, gallium, or indium. 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.

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.

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". 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.

See also

• coloradoite

Related compounds

• Cadmium telluride
• HgSe
• HgCdTe

References

• Properties of mercury cadmium telluride, Ed. J. Brice and P. Capper, EMIS datareview, (INSPEC, IEE, London, UK, 1987).
• Properties of Narrow-Gap Cadmium-Based Compounds Ed. P. Capper (INSPEC, IEE, London, UK, 1994) ISBN 0-85296-880-9
• Tellurium and Tellurides, D. M. Chizhikov and V. P. Shchastlivyi, 1966, Nauka Publishing, Moscow
• Mercury selenide stoichiometry and phase relations in the mercury-selenium system, N. Z. Boctor and G. Kullerud, Journal of Solid State Chemistry Vol. 62, pp. 177–183 (1986) doi:10.1016/0022-4596(86)90229-X
• Total-energy study of the equation of state of HgTe and HgSe, Z. W. Lu, David Singh, and Henry Krakauer, Phys. Rev. B vol. 39, pp. 10154 (1989).
• Quantum Spin Hall Insulator State in HgTe Quantum Wells, M. Konig et al., Science 318 766 (2007).

External links

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