HgTe

HgTe, or mercury telluride, is a binary semiconductor compound formed from mercury and tellurium. It crystallizes in the zincblende structure, similar to other II-VI semiconductors. HgTe is notable for its zero-bandgap or semimetallic nature at ambient conditions. This unique electronic property arises from the inverted band ordering of its valence and conduction bands. At low temperatures or under strain, HgTe can transition into a topological insulator phase, exhibiting conducting surface states protected by time-reversal symmetry.

The synthesis of HgTe can be achieved through various techniques, including molecular beam epitaxy (MBE) and chemical vapor deposition (CVD). The material is typically grown as thin films or epilayers on substrates like cadmium telluride (CdTe) or gallium arsenide (GaAs). Its optical properties are characterized by strong absorption in the infrared region of the electromagnetic spectrum, making it a candidate for infrared photodetectors and imaging applications.

HgTe alloys with cadmium telluride (CdTe) to form HgCdTe, a tunable alloy system widely used in infrared optoelectronics. By varying the cadmium content (x in Hg1-xCdxTe), the bandgap can be precisely controlled, enabling devices that operate across a broad range of infrared wavelengths. Research into HgTe continues to explore its potential in spintronics and quantum computing due to its topological properties.