An Integrated H-type Method to Measure Thermoelectric Properties of Two-Dimensional Materials

Abstract

This paper presents a new integrated H-type method for precisely characterizing the thermoelectric properties of suspended two-dimensional (2D) materials. The current method combines the micro-device electrical measurement and laser heating together. The electrical measurement offers high accuracy, while the measurement principle and operation can be much simplified by using the noncontact laser heat source. The 2D material is suspended between two metallic nanofilms to form a H-type structure, i.e. named as H-type method. The metallic nanofilms can be used as an electrical Joule heater and a temperature sensor. By simply changing the external circuit, the electrical conductivity, thermal conductivity and Seebeck coefficient can be measured on the same nanomaterial sample, simultaneously. Thus, the main origin of measurement uncertainty caused by the sample discrepancy can be avoided. In the measurement, the laser absorption rate of the 2D material can be obtained as well. Taking monolayer graphene as an example, a detailed uncertainty analysis was carried out. This work provides a reliable and accurate measurement method to achieve full thermoelectric properties of 2D materials, setting a foundation for practical design of efficient 2D thermoelectric devices.