Cross-Plane Thermoelectric Transport Across Hetero-Epitaxial Growth of Nano-Flakes Bi₂Se₃ / Graphene Multi-layer

Jen Kai Wu^2*, Yan-Ting Chuang³, Mario Hofmann^2,3, Ya-Ping Hsieh^1,4, Yuan-Huei Chang^2,3

¹Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei, Taiwan
²Institute of Physics, National Taiwan University, Taipei, Taiwan
³Institute of Applied Physics, National Taiwan University, Taipei, Taiwan
⁴institute of Opto-Mechatronics, National Chung Cheng University, Chia-Yi, Taiwan

* Presenter:Jen Kai Wu, email:D01222011@ntu.edu.tw

The fabrication and properties of Bi₂Se₃ nano-flakes / graphene (BSG) hetero-structure multi-layer are reported. In our study, rhombohedral crystal structure Bi₂Se₃ nano-flakes were grown on graphene by physical vapor deposition method. Structural investigations of our BSG indicate that the sample has good crystalline quality. We propose that we obtain higher figure of merit by reducing the thermal conductance contributed by phonon because the Wiedemann–Franz law states that the ratio of σT/κe is a constant, where σ is the electrical conductivity, κe represents the thermal conductivity contributed by electron, and T is the absolute temperature. To reduce the thermal conductance of our device, a BSG layer was transferred by wet transfer to SiO₂ substrate and stack multi-layer. It was found that as the number of layers increases, the thermal conductance is lower. The results illustrate that our device is potentially an excellent candidate for thermoelectric applications in the cross-plane direction.

Keywords: Figure of Merit, Thermal Conductance, Bi₂Se₃, Graphene, Thermoelectric