Improved performance of thermoelectric micro-device by integrating a layered Bi2Te3 film

•Highly oriented Bi2Te3 thin film is fabricated and integrated into device.•The layered Bi2Te3 film is beneficial for the improvement of thermoelectric properties.•2-μm-thick film device shows excellent power generation and cooling performance.•Introduction of such special layered film into device is a very promising approach.

An approach for fabrication of planar devices integrating layered Bi2Te3 thin-films with different microscale thicknesses instead of bulk materials is reported. The films were prepared by the radio-frequency magnetron sputtering. The microstructure, composition, and thermoelectric (TE) properties of the thin-films were characterized using X-ray diffraction, scanning electron microscopy with energy dispersive X-ray spectroscopy, and a TE measurement system, respectively. The results show that the Bi2Te3 films with layered microstructure possess promising TE properties. The power generation and cooling performance of parallel micro-devices with n-type thermolegs were tested and found to be superior to those of bulk material devices. For a typical parallel device with 38 optimized 2-μm-thick legs, the output voltage, estimated maximum power and corresponding power density are up to 5.6 mV, 6.53 μW and 43 mW cm− 2, respectively, for a temperature difference of 81 K. The coefficient of performance (COPmax) of the device was also estimated. The minimum value of COPmax approaches 6.8 at ΔT = 3.2 K. The results prove that high performance of micro-device with low internal resistance can be realized by integrating special layered Bi2Te3 thin-films.