Molybdenum telluride

mP12, P21/m, No. 11 (β or 1T)Molybdenum(IV) telluride, molybdenum ditelluride or just molybdenum telluride is a compound of molybdenum and tellurium with formula MoTe2, corresponding to a mass percentage of 27.32% molybdenum and 72.68% tellurium. It can crystallise in two dimensional sheets which can be thinned down to monolayers that are flexible and almost transparent. It is a semiconductor, and can fluoresce. It is part of a class of materials called transition metal dichalcogenides. As a semiconductor the band gap lies in the infrared region. This raises the potential use as a semiconductor in electronics or an infrared detector. Molybdenum(IV) telluride, molybdenum ditelluride or just molybdenum telluride is a compound of molybdenum and tellurium with formula MoTe2, corresponding to a mass percentage of 27.32% molybdenum and 72.68% tellurium. It can crystallise in two dimensional sheets which can be thinned down to monolayers that are flexible and almost transparent. It is a semiconductor, and can fluoresce. It is part of a class of materials called transition metal dichalcogenides. As a semiconductor the band gap lies in the infrared region. This raises the potential use as a semiconductor in electronics or an infrared detector. MoTe2 can be prepared by heating the correct ratio of the elements together at 1100 °C in a vacuum. Another method is via vapour deposition, where molybdenum and tellurium are volatilised in bromine gas and then deposited. Using bromine results in forming an n-type semiconductor, whereas using tellurium only results in a p-type semiconductor. The amount of tellurium in molybdenum ditelluride can vary, with tellurium being slightly deficient unless it is added in excess during production. Tellurium molecular proportion range from 1.97 to 2. Excess tellurium deposited during this process can be dissolved off with sulfuric acid. By annealing molybdenum film in a tellurium vapour at 850 to 870 °C for several hours, a thin layer of MoTe2 is formed. An amorphous form can be produced by sonochemically reacting molybdenum hexacarbonyl with tellurium dissolved in decalin. Molybdenum ditelluride can be formed by electrodeposition from a solution of molybdic acid (H2MoO4) and tellurium dioxide (TeO2). The product can be electroplated on stainless steel or indium tin oxide. In powdered form MoTe2 is black. Very thin crystals of MoTe2 can be made using sticky tape. When they are thin around 500 nm thick red light can be transmitted. Even thinner layers can be orange or transparent. An absorption edge occurs in the spectrum with wavelengths longer than 6720 Å transmitted and shorter wavelengths heavily attenuated. At 77 K this edge changes to 6465 Å. This corresponds to deep red. MoTe2 reflects about 43% in the infrared band but has a peak at 234.5 cm−1 and a minimum at 245.8 cm−1.