Surface Conductance Induced Dielectrophoresis of Semiconducting Single-Walled Carbon Nanotubes

• Published in: Nano letters 2004-08, Vol.4 (8), p.1395-1399
• Main Authors: Krupke, Ralph, Hennrich, Frank, Kappes, Manfred M, v. Löhneysen, Hilbert
• Format: Article
• Language: English
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Cross-disciplinary physics: materials science; rheology; Electronic structure and electrical properties of surfaces, interfaces, thin films and low-dimensional structures; Exact sciences and technology; Materials science; Nanoscale materials and structures: fabrication and characterization; Nanotubes; Physics; Surface conductivity and carrier phenomena
• ISSN: 1530-6984; 1530-6992
• DOI: 10.1021/nl0493794

Dielectrophoresis on surfactant-stabilized single-walled carbon nanotube (SWNT) suspensions has been demonstrated to separate metallic from semiconducting tubes by their different electric field-induced polarizabilities. Here we report that the interaction between SWNTs and the surfactant induces a nanotube surface conductance which gives rise to a unique electric field frequency dependence of the nanotube dielectrophoresis. We observe a surfactant concentration dependent crossover frequency enabling separation of metallic from semiconducting SWNTs at high frequency and deposition of metallic and semiconducting SWNTs at low frequency − both being important aspects for building nanotube-based electronics. Moreover, the data demonstrate that the theoretical description of dielectrophoretic forces is valid beyond the dimensions of cells or viruses.