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

Abstract

We report on a direct comparison of the out-of-plane thermoelectric properties, such as Seebeck coefficient and electrical conductivity, of 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 129.4, 143.3, and 152.2 mu V/K, respectively. Such behavior is seen because the increasing number of MoS2 layers increases the density of states of a system. In contrast to conventional thermoelectric materials, the electrical conductivities of these MoS2 films have the same tendency as the Seebeck coefficients. Our results show that thermoelectric devices can utilize the out-of-plane properties of MoS2 thin films with high power factors.