291547 Vapor Phase Growth of Bismuth Telluride Nanoplatelets On Flexible Polyimide Films

Monday, October 29, 2012
Hall B (Convention Center )
Benjamin C. Ivey, Chemical and Biomolecular Engineering, Georgia Institute of Technology, Atlanta, GA

To facilitate flexible thermoelectric modules device development and the fundamental science of topological insulators, bismuth telluride (Bi2Te3) nanoplatelets were synthesized on flexible polyimide films (Kapton films) by a chemical vapor transport process. Bi2Te3 has been the predominant thermoelectric material for applications below 300oC, and Bi2Te3 nanoplatelets display effects of topological insulators, matter with conducting states that are protected against time reversal symmetry perturbations. Unfortunately, mostly rigid substrates have been used in chemical vapor transport syntheses of Bi2Te3 nanoplatelets. To grow the nanoplatelets, the Kapton film was first wet-cleaned with acetone and isopropanol and dry-cleaned with oxygen plasma. Then, the film was placed downstream from Bi2Te3 powder in a Lindberg/Blue horizontal tube furnace. Heating of the Bi2Te3 powder under vacuum pressures formed Bi2Te3 vapor that was carried downstream by argon gas and deposited on the polyimide film substrate to form nanoplatelets. We developed a dry transfer technique that takes advantage of the electrostatic attraction between 3-aminopropyltrimethoxysilane (APTMS) and Bi2Te3 to transfer these as-grown nanoplatelets from the Kapton films onto SiO2(300 nm)/Si substrates for atomic force microscopy (AFM) characterization. AFM observations revealed that triangular, hexagonal, and ribbon-shaped nanoplatelets with surface areas within 3 - 40 µm2 were synthesized on the Kapton films. The nanoplate thickness range was 10 - 100 nm, which was thinner than Bi2Te3 nanoplatelets grown on rigid glass and silicon substrates. We have demonstrated that Bi2Te3 nanoplatelets can be synthesized on flexible substrates and with characteristic thicknesses of topological insulators. We also suggest a growth mechanism based on our AFM observations.

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