Evaluation of Thermoelectric Performance of Bi2Te3 Films as a Function of Temperature Increase Rate during Heat Treatment

Thin film thermoelectric generators are expected to be applied as power supplies for various Internet of Thing devices owing to their small size and flexible structure. However, the primary challenges of thin film thermoelectric generators are to improve their thermoelectric performance and reduce their manufacturing cost. Hence, Bi2Te3 thin films were deposited using direct current magnetron sputtering, followed by heat treatment at 573 K with different temperature increase rates ranging from 4 to 16 K/min. The in-plane Seebeck coefficient and electrical conductivity were measured at approximately 293 K. The in-plane thermal conductivity was calculated using the models to determine the power factor (PF) and dimensionless figure of merit (ZT). The temperature increase rate clearly affected the atomic composition, crystal orientation, and lattice strains, but not the crystallite size. The PF and dimensionless ZT increased as the temperature increase rate increased. The highest PF of 17.5 mu W/(cm center dot K-2) and ZT of 0.48 were achieved at a temperature increase rate of 16 K/min, while the unannealed thin film exhibited the lowest PF of 0.7 mu W/(cm center dot K-2) and ZT of 0.05. Therefore, this study demonstrated a method to enhance the thermoelectric performance of Bi2Te3 thin films by heat treatment at the appropriate temperature increase rate.

Automated summary

Thin film thermoelectric generators are expected to be used in various IoT devices due to their small size and flexibility. Improving thermoelectric performance and reducing manufacturing costs are primary challenges. This study demonstrated that by heat treating Bi2Te3 thin films at specific temperature increase rates, their thermoelectric properties can be significantly enhanced, leading to higher PF and ZT values.