BROWSE
Detail
Conference Paper
Process-Dependent Interfacial Chemistry and Elemental Diffusion in Bi2Se3/Nb Heterostructures
Cited - time in 
Share 
Share
- Authors
- CHO Dae-Hyung, HWANG Tae-Ha, CHUNG Yong-Duck, LEE Suji, LEE Woo-Jung
- Issue Date
- 2026-04
- Citation
- 한국물리학회 학술 논문 발표회 (봄) 2026, pp.1-1
- Publisher
- 한국물리학회
- Language
- English
- Type
- Conference Paper
- Abstract
- Bi2Se3/Nb heterostructures have emerged as promising platforms for investigating superconducting proximity effects and superconducting topological systems. Achieving functional heterostructures requires simultaneous preservation of the superconducting properties of Nb and the crystalline integrity of Bi2Se3, while minimizing interfacial chemical reactions. However, the Nb surface is chemically active toward chalcogenide compounds, frequently leading to interdiffusion and secondary phase formation that degrade the Bi2Se3 layer. In this study, the evolution of interfacial chemistry and elemental diffusion in Bi2Se3/Nb structures is systematically examined by modifying growth-related parameters, including substrate material, post-growth annealing temperature, and the repetition number of alternating Bi and Se deposition cycles. Approximately 20-QL-thick Bi2Se3 films were fabricated by sequential thermal evaporation of Bi and Se under high vacuum (below 10⁻⁷ Torr). The Nb thin films were deposited using DC magnetron sputtering. Thermal annealing plays a decisive role in determining interface stability. When Bi2Se3 is grown on Nb and annealed above 175 °C, significant diffusion of Nb and oxygen into the Bi2Se3 layer is observed, accompanied by the emergence of Bi–O and Nb–Se bonding and a measurable reduction in film thickness. In contrast, annealing below 150 °C effectively suppresses such diffusion, allowing Bi–Se bonding to dominate. Nevertheless, an interfacial layer with a thickness of approximately 5 nm, attributed to an NbxSey phase, forms irrespective of annealing temperature. This contrasts sharply with Bi2Se3 films grown on SiO2, which retain structural stability without interfacial reaction even at temperatures exceeding 200 °C, underscoring the strong chemical influence of Nb. The repetition number of Bi/Se deposition cycles is also found to significantly affect diffusion behavior. A higher repetition number reduces Nb penetration into the Bi2Se3 layer and improves stoichiometric stability, whereas fewer cycles result in enhanced Nb incorporation and Bi deficiency. Importantly, the superconducting transition temperature of the Nb layer remains above 8.7 K under all processing conditions, indicating that Nb superconductivity is preserved despite interfacial modification. These findings clarify the diffusion mechanisms and interfacial phase formation in Bi2Se3/Nb systems and provide process guidelines for achieving structurally stable superconducting heterostructures.
- Keyword
- Bi2Se3/Nb heterostructure, Interfacial chemistry, Elemental diffusion, Superconducting thin film, Topological insulator
- KSP Keywords
- 5 nm, Annealing temperature, Chalcogenide compounds, Film thickness, High vacuum, Influence of Nb, Interface stability, Interfacial chemistry, Interfacial layer, Interfacial modification, Interfacial phase