Layer number dependence of out-of-plane electrical conductivity and Seebeck coefficient in continuous mono- to multilayer MoS2 films

Abstract

We report on direct comparison of out-of-plane thermoelectric properties, such as Seebeck coefficient and electrical conductivity, of the atomically thin MoS2 films. The films were prepared by a chemical vapor deposition method and were simultaneously investigated using a Cu-sandwiched structure. Specifically, this is the first study that measures the out-of-plane Seebeck coefficients of atomically thin mono- and bilayer MoS2 at 300 K. At room temperature, out-of-plane Seebeck coefficients for MoS2 films with one, two, and seven layers were measured to be approximately 42.9, 72.8, and 112.4 μV/K, respectively. Such behavior is seen because the increasing number of MoS2 layers increases the density of states of a system. Contrary to the conventional thermoelectric materials, the electrical conductivities of these MoS2 films have the same tendency as the Seebeck coefficients. Our results show that the thermoelectric devices can utilize out-of-plane properties of MoS2 thin films with high power factors