Selective sorting of metallic/semiconducting single-walled carbon nanotube arrays by ‘igniter-assisted gas-phase etching’

Abstract

Towards future applications, like nanoelectronic devices, techniques to obtain single-walled carbon nanotubes (SWNTs) with specific electronic types (semiconducting or metallic ones) are urgently required. Herein, we developed a rational approach for the preferential etching of either metallic or semiconducting SWNTs assisted by selective adsorption of molecules onto the corresponding SWNTs. The adsorbed molecules were easily oxidized under a temperature below the threshold for the etching of SWNTs, and the heat generated during oxidation could accelerate the etching process of nearby SWNTs. Based on this design, we could obtain semiconducting-enriched or metallic-enriched SWNT arrays with a purity of 93% and 86% assisted by the adsorption of different molecules. Further in-situ observation by polarized optical microscope ensured the acceleration of the etching process of SWNTs adsorbed by the molecular igniters. Our method combines the advantages of solution separation (high selectivity and diversity) and gas-phase etching (clean and high efficiency), providing more feasibility in obtaining SWNT horizontal arrays with uniform properties.