Large Thermoelectricity via Variable Range Hopping in Chemical Vapor Deposition Grown Single-layer MoS2

TL;DR

This study reveals high thermoelectric efficiency in CVD-grown single-layer MoS2, driven by variable range hopping, with potential implications for future thermoelectric devices.

Contribution

First investigation of thermoelectric properties in CVD-grown single-layer MoS2, demonstrating large thermopower and variable range hopping behavior.

Findings

Thermopower up to ~30 mV/K at room temperature.

Seebeck coefficient follows S~T^1/3, indicating 2D variable range hopping.

Large thermoelectric response surpassing other 2D materials.

Abstract

Ultrathin layers of semiconducting molybdenum disulfide (MoS2) offer significant prospects in future electronic and optoelectronic applications. Although an increasing number of experiments bring light into the electronic transport properties of these crystals, their thermoelectric properties are much less known. In particular, thermoelectricity in chemical vapor deposition grown MoS2, which is more practical for wafer-scale applications, still remains unexplored. Here, for the first time, we investigate these properties in grown single layer MoS2. Micro-fabricated heaters and thermometers are used to measure both electrical conductivity and thermopower. Large values of up to ~30 mV/K at room temperature are observed, which are much larger than those observed in other two dimensional crystals and bulk MoS2. The thermopower is strongly dependent on temperature and applied gate voltage with a large enhancement at the vicinity of the conduction band edge. We also show that the Seebeck coefficient follows S~T^1/3 suggesting a two-dimensional variable range hopping mechanism in the system, which is consistent with electrical transport measurements. Our results help to understand the physics behind the electrical and thermal transports in MoS2 and the high thermopower value is of interest to future thermoelectronic research and application.