Micro Four-Point Probe for Anisotropic Thermal Diffusivity Mapping

High-resolution microscale thermal diffusivity characterization is vital for a deeper understanding of materials used in thermoelectric energy harvesters, nano/microelectronic, and thermal management. Analyzing the thermal properties of individual grains can advance the development of these materials, however, only a few techniques currently exist for microscale characterization of the thermal properties.<br/>Micro four-point probe (M4PP) has been widely used by the semiconductor industry to characterize thin films for sheet resistance, carrier mobility, and magnetoresistance. Currently, we are exploring the use of M4PP for estimating the thermal properties of materials including the Seebeck coefficient, thermal diffusivity, and the temperature coefficient of resistance.<br/>Here, I will present a novel method for measuring the thermal diffusivity of individual grains with varying orientations using the M4PP. The local thermal diffusivity measurements were performed on a prototypical bulk thermoelectric Bi₂Te₃sample at room temperature. The thermal diffusivity was then correlated with the orientation of the grains measured with electron-backscattered diffraction (EBSD). The method for measuring thermal diffusivity proposed in this study provides rapid and accurate thermal characterization, thereby opening up opportunities for a detailed understanding of microstructures.