| About this Abstract |
| Meeting |
MS&T24: Materials Science & Technology
|
| Symposium
|
2024 Graduate Student Poster Contest
|
| Presentation Title |
SPG-55: Intrinsically Large Effective Mass and Multi-Valley Band Characteristics of n-Type Bi2-Bi2Te3 Superlattice-Like Films |
| Author(s) |
Yujie Ouyang |
| On-Site Speaker (Planned) |
Yujie Ouyang |
| Abstract Scope |
Thermoelectric superlattices are expected to be an important strategy for excellent thermoelectric performances. The superlattices of (Bi2)m(Bi2Te3)n homologous series are well-known for low lattice thermal conductivity and intriguing topological surface states. However, the impacts of electronic structure on the thermoelectric performance were still not well-understood in (Bi2)m(Bi2Te3)n. In this work, Bi2-Bi2Te3 superlattice-like films with adjustable Bi2/(Bi2+Bi2Te3) molar ratio (R) were successfully fabricated by the MBE technique. Angle-resolved photoemission spectroscopy measurements combined with theoretical calculations revealed the conduction band evolution from single-valley to multi-valley as R = 0.46, leading to intrinsically high carrier effective mass of 3.9 m0 and improved thermoelectric power factor of 1.49 mW·m–1·K–2 at 420 K, outperforming that of other (Bi2)m(Bi2Te3)n superlattices. This work lays an essential foundation on understanding the electronic structure and further improving thermoelectric performances of (Bi2)m(Bi2Te3)n homologous series. |