The crystal strucure of Mercury Telluride

Description

Mercury Telluride is a binary inorganic compound composed of tellurium and mercury elements. It is a black crystal at room temperature and is ideal for making infrared detectors. It is the bulk gapless semiconductor.

Synthesis method

HgSe and HgTe are prepared by direct reaction of the elements in evacuated thick-walledquartz capsules. Because the vapor pressure of free Hg at the melting point of HgSe is over100 atm, explosions are frequent. Explosions of HgTe, which has a melting point of 670℃,are less frequent. Ingots of HgSe and HgTe are prepared by slowly heating the capsulescontaining the elements at temperatures well below the compound melting point until the reaction has occurred and little or no free Hg exists. The capsules are then heated to approximately 30 °C above the compound melting points and slowly lowered through a Bridgman furnace.

The ingots so formed are polycrystalline with average crystallite sizesof the order of 5 mm. Hall and resistivity measurements over the interval from 77°K to 300°K indicate the HgSe to be invariably n-type，whereas all HgTe ingots prepared to date have been p-type. The purity, of the order of 1017-1018cm-3, is believed to be controlled by deviations from stoichiometry; the HgSe containing excess Hg atoms either interstitially or due to vacancies in the Se sublattice, and the HgTe containing excess Teatoms, either interstitially or due to vacancies in the Hg sublattice.

Crystal Structure

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. The crystal structure is Sphalerite, cF8. The space group is F43m, No. 216.