Surface properties of topological insulator Bi2Se3 nanoparticles separated by impedance spectroscopy

• Published in: Applied physics letters 2017-06, Vol.110 (25)
• Main Authors: Choi, Dong Min, Lee, Kyu Won, Jeon, Gi Wan, Kim, Do Wan, Lee, Cheol Eui
• Format: Article
• Language: English
• Subjects: Aluminum oxide; Applied physics; Electrical properties; Electrical resistivity; Equivalent circuits; Impedance spectroscopy; Inductance; Nanoparticles; Scientific apparatus & instruments; Spectrum analysis; Surface properties; Surface resistivity; Temperature dependence
• ISSN: 0003-6951; 1077-3118
• DOI: 10.1063/1.4986960

We have separated the surface and bulk electrical properties of the Bi2Se3 nanoparticles by means of impedance spectroscopy. An equivalent circuit analysis of the complex impedance data comprising two separate resistance components, R B and R S, and two separate inductance components, L B and L S, enabled us to separate the bulk and surface properties of the topological insulator. One of the resistance components, R S, attributed to the surface, showed no temperature dependence, whereas the other, R B, attributed to the bulk, showed a weak metallic behavior. With increasing surface-to-bulk ratio by mixing with insulating Al2O3 nanoparticles up to the ratio of 1:1, the surface resistivity showed decrease up to ∼70%, whereas the bulk resistivity showed increase up to ∼150%. While the bulk state showed increasing electrical resistivity up to 200% with aging up to 30 days, the surface state resistivity did not show an aging effect.