Films enriched with semiconducting single-walled carbon nanotubes by aerosol N2O etching

Abstract

Semiconducting single-walled carbon nanotubes (SWCNTs) are of particular interest to electronics. As most of synthesis methods yield 1/3 of metallic SWCNTs, the route for a purely semiconducting species is a complex multistep procedure. Herein, we report a simple one-step method for selective etching of metallic SWCNTs in the aerosol phase with nitrous oxide. Our approach is based on a tandem of two flow reactors, where the first one is needed to produce individual SWCNTs, and the second one is to eliminate metallic SWCNTs due to their faster oxidization rate. The oxidant (N2O) adsorption on the SWCNT surface was modelled by DFTB taking into account geometric characteristics of the nanotube and its electronic properties, resulting in less N2O adsorption energy for metallic SWCNTs of some chiralities than for semiconducting ones. Thus, we obtained SWCNT films enriched with semiconducting nanotubes up to optical selectivity of 97% by treatment of pristine SWCNT aerosols for 6 s at 600 °C in an atmosphere of 30% N2O. The treated films show a turnaround of the temperature dependence of the resistance. As a proof of the concept, enriched SWCNT films were utilized as a channel material for thin film field effect transistors, which show an average improvement of ON/OFF current ratio from 1- 10 to 10 - 104 for the same open state resistance for the statistical sampling based on more than 7500 devices.