Mercury(II) telluride
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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.
| General | |
|---|---|
| Name | mercury telluride |
| Chemical Formula | HgTe |
| Appearance | near black cubic crystals |
| CAS number | [12068-90-5] [1] |
| Structure | |
| Formula weight | 328.19 u |
| Lattice constant | 0.646 nm |
| Crystal structure | zincblende |
| Physical | |
| State of matter at STP | solid |
| Melting point at SP | 943 K |
| Boiling point at SP | ? |
| Specific gravity | 8.1 |
| Electronic | |
| Band gap at 300 K | -0.01 eV |
| Electron effective mass | 0.002 me |
| Light hole effective mass | 0.002 me |
| Heavy hole effective mass | 0.6 me |
| Electron mobility at 300 K | 15000 cm²/(V·s) |
| Hole mobility at 300 K | 8000 cm²/(V·s) |
| Precautions | |
| NFPA 704 | |
| Toxic | YES |
| Decomposition products | Highly toxic mercury and tellurium fumes |
| SI units were used where possible. | |
Contents |
[edit] 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 5.2x10-6.K-1. Static dielectric constant 20.8, dynamic dielectric constant 15.1. Thermal conductivity is low at 2.7W.m-1.K-1. HgTe bonds are weak leading to low hardness values. Hardness 2.7x107 kg. m-2.
[edit] 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.
[edit] Chemistry
HgTe bonds are weak, the enthalpy of formation is around -32kJ/mol, this value is less than a third of the related compound cadmium telluride. HgTe is easily etched by acids, such as hydrobromic acid.
[edit] 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.
[edit] See also
[edit] Related compounds
[edit] 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).
[edit] External links
- Thermophysical properties database at Germany's Chemistry Information Centre, Berlin
