Temperature dependence of the electrical conductivity and thermoelectric power in MoTe₂ single crystals

Abstract

Thermoelectric power and dc electrical conductivity measurements are made on MoTe, single crystals in a wide temperature range (77 to 770 K). The results are analyzed on the basis of impurity conduction. It is shown that three processes contribute to the total conductivity: hopping conduction between impurity sites, scattering by optical modes, and, in the intrinsic domain, scattering by impurities. The thermal energy gap (0.99 eV) is approximately the same as the optical one (1.03 eV). The effective mass of electrons in the conduction band is not very different from the mass of the free electron (m* == 0.76rn), and the dielectric constant of the medium is K = 34.The agreement between theoretical and experimental results is quite good. A comparison with previous results performed on compact polycrystalline samples is given.Des mesures de pouvoir thermoklectrique et de conductivitk klectrique sont effectukes entre 77 e t 770 K sur des kchantillons monocristallins MoTe,. Les rksultats expkrimentaux sont analyshs en terme de conduction par impuretks. On montre que la conductivith fait intervenir trois mkcanismes: conduction par sauts cntre sites d'impuretks, interaction avec 1es phonons optiques et, dans le domaine intrinsAque, interaction avec les impuretks. Les riesures de la bande d'knergie interdite thermique e t optique sont peu diffkrentes (0,99 e t 1.03 eV). La masse effective des electrons dans la bande de conduction est proche de celle de I'klectron libre (m* = 0,76m) e t la constante diBlectrique du milieu est K 34. L'accord entre rksultats thhoriques e t expkrimentaux est tr6s satisfaisant. Les rhsultats sur les kchantillons monocristallins sont compares & ceux obtenus prkckdemment sur des irchantillons polycristallins.

Dependence of the Total Mobility in a One‐Band Model Applicationto n‐Type MoTe2

“…I n the present paper, we explain the experimental rcsults which have been obtained in [3] on the basis of the theoretical model described in [l]. In order to study the oneband conduction model when two scattering mechanisms are present, the DebyeConwell formula and Mathiessen's rule have been compared.…”

“…(i) It has been shown in [3] that MoTe, behaves a s a pure semiconductor. The impurity at,oms of bromine have one outer shell electron more than the tellurium ones.…”

“…Less recently, transport coefficient measurements had been performed in MoTe, single crystals [3], prepared by the vapour transport method with bromine as transport reagent in a wide temperature range (77 to 770K). It had been shown that all the processes which take part in the conduction mechanisms were governed by the presence of bromine leading to n-type conduction.…”

Ambipolar MoTe2 Transistors and Their Applications in Logic Circuits

“…The mechanical properties of the single‐walled MoTe 2 nanotubes were found to strongly depend on the diameter and chirality of the tubes . Although the electrical properties of bulk MoTe 2 have been studied, layered MoTe 2 flake structures have not been investigated thus far and are still puzzling.…”

Mesure assistée par miniordinateur du pouvoir thermoélectrique de petits échantillons

“…Par ailleurs, les mesures du P.T.E. et de la conductivité électrique nous ont permis de caractériser les propriétés de MoTe2 monocristallin [10] préparé par la méthode de transport en phase gazeuse (agent de transport : brome) et des composés MoTe2-x [11,12] (0 x 0,05) appauvris en tellure. Cette méthode de caractérisation s'est révélée très fructueuse en raison de la précision des résultats confirmés par d'autres mesures (optique et diffraction X).…”