Local Electrical Investigations of Nitric Acid Treatment Effects on Carbon Nanotube Networks

Abstract

Nitric acid is a commonly used chemical in preparing and functionalizing carbon nanotube (CNT) networks. It is also used to enhance the conductivity of CNT-based networks or films, which is usually attributed to p-type doping by NO3– ions. We used local electrical characterization methods based on atomic force microscopy to elucidate the effects of nitric acid treatments on sparse and random CNT networks. IV characteristics of CNT network devices before and after nitric acid treatments are obtained along with local electrical characteristics with both scanning gate microscopy and electrostatic force microscopy. Our results show both p-type doping of CNTs and reduction of CNT–CNT junction resistances after nitric acid treatments.