Mercury(II) telluride

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

General
Name	mercury telluride
Chemical Formula	HgTe
Appearance	near black cubic crystals
CAS number	CASREF|CAS=12068-90-5
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 "m"e
Light hole effective mass	0.002 "m"e
Heavy hole effective mass	0.6 "m"e
Electron mobility at 300 K	15000 cm²/(V·s)
Hole mobility at 300 K	8000 cm²/(V·s)
Precautions
NFPA 704
Toxic	red|YES
Decomposition products	Highly toxic mercury and tellurium fumes
SI units were used where possible.

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.

ee 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).

External links

* [http://www.fiz-chemie.de/infotherm/html/molpages/03%5C06%5C/mol30632.html Thermophysical properties database] at Germany's Chemistry Information Centre, Berlin