Thermal and Electronic Properties of Exfoliated Metal Chalcogenides

Abstract

The thermal conductivity of layered metal chalcogenides such as <TEX>$MT_2$</TEX> (M = Mo, W; T = S, Se) shows a marked decrease after exfoliation and subsequent restacking process. Random stacking of two-dimensional crystalline sheets circumvents thermal conduction pathways along a longitudinal direction, which results in a reduction in thermal conductivity. <TEX>$WS_2$</TEX> and <TEX>$WSe_2$</TEX> compounds retain p-type conducting behavior after exfoliation and restacking with decreased electrical conductivity due to the change in carrier concentration. <TEX>$MoSe_2$</TEX> compound exhibits metallic behavior < <TEX>$130^{\circ}C$</TEX> with a small Seebeck coefficient, which results from metastable 1T-<TEX>$MoSe_2$</TEX> structure of the restacked phase.