Improved field emission characteristics of individual carbon nanotube coated with boron nitride nanofilm

Abstract

An individual multiwall carbon nanotube (CNT) synthesized without a catalyst by an arc discharge method is bonded to a tungsten tip. Field emission characteristics of the individual CNT coated with a boron nitride (BN) nanofilm are investigated. The BN film is synthesized by plasma-assisted chemical vapor deposition method in which boron trichloride (BCl3) and nitrogen (N2) are used as source gases. Deposition of the BN film with a thickness less than 10nm onto the individual CNT is attempted. Field emission characteristics are measured in the chamber evacuated to 2×10−8Pa. An anode electrode is set 25mm away from the CNT sample. The turn-on electric field, designated as an electric field at an emission current of 1.0nA, is compared between individual CNTs with and without the BN nanofilm. A significant reduction in the turn-on electric field is achieved by coating with the BN nanofilm. The turn-on electric field is estimated to be 1.2×10−2V∕μm for the uncoated individual CNT sample, and the turn-on electric field is estimated to be 8.2×10−3V∕μm for the CNT sample coated with BN nanofilm. Moreover, stable operation is demonstrated at an emission current as high as 1×10−5A.