Influence of the stoichiometry deviation on the electrical properties of MoTe2-x
Year: 1988
Type: article
Abstract: Transport coefficient measurements (electrical conductivity, Hall effect, thermoelectric power) have been performed on single crystals of MoTe 2-x (x = 0.01 and 0.015) in a wide range of temperatures. The samples were prepared by a based Te flux method and the deviation from stoichiometry was obtained by a thermal treatment. Experimental results are interpreted on the basis of a compensated p-type semiconductor model. The lacunar origin of the two impurity levels is clearly shown. For a weak departure from stoichiometry, the carriers are scattered in two ways : ionized impurities and thermal lattice modes. For a larger departure, the donor and acceptor levels broaden in two narrow energy bands. At low temperatures, the conduction mechanisms are mainly governed by a thermal hopping of small polarons in these bands. At higher temperatures, the contribution of the extended states must be taken into account. It is shown that the presence of Te-lacunar-sites leads to a greater polarization of the material and a much higher interaction between the valence and the acceptor energy bands. The model adopted here is in agreement with the band structure of the group VI transition metal dichalcogenides which have a trigonal prism coordination.
Source: Journal de physique
Authors: A. Bonnet, A. Conan, M. Spiesser, M. Zoaeter
Language: French
Subfield: Materials Chemistry
Field: Materials Science
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W2013378736