Field emission energy distribution studies of single multi-walled carbon nanotube emitter with gas adsorptions

Abstract

The field emission electron energy distribution (FEED) investigation on the individual carbon nanotube (CNT) is a powerful approach to study the intrinsic electronic properties, including the work function and field emission energy level, for CNT devices. We fabricated the single multi-walled carbon nanotube (MWNT) emitter by the solution evaporation dielectrophoretic process after the chemical vapor deposition (CVD) synthesis of the MWNT film. The FEED properties of the MWNT emitter in hydrogen and nitrogen environments were investigated. The FEED peaks shifted up gradually in both hydrogen and nitrogen ambiences, indicating the effective work function reduction effect with gas adsorptions. The amounts of spectrum displacements increased with raising gas partial pressures, with larger displacements of up to 0.65 eV for hydrogen between 10−7 Pa and 10−4 Pa. The double peak spectra imply that emission electrons could be from the hexagonal and the pentagonal carbons. Meanwhile, high carbon content was detected in the ultimate vacuum, attributed highly to the MWNT etching from the emission. This investigation suggests that the work function variation plays key role for the field emission instability and the pressure sensing effect of CNT emitters.