Enhanced field emission of vertically aligned core-shelled carbon nanotubes with molybdenum oxide encapsulation

Abstract

The field emission characteristics of the core-shelled nanostructures obtained by directly coating molybdenum oxide onto vertically aligned multiwalled carbon nanotubes (MWNTs) was investigated. A metal-organic chemical vapor deposition technique was used with Mo(CO)6 as the precursor and films deposited at process temperatures of 200, 400, and 700 °C. X-ray photoelectron spectroscopy, scanning electron microscopy, and x-ray diffraction were used to study and understand the material properties of the deposited coatings. Enhanced field emission performance was observed for molybdenum oxide coated MWNT samples at 400 °C with a turn-on field of 1.33 V μm−1 and a field enhancement factor β estimated to be ∼7000. The enhanced performance may be due to both the shape of the coated emitters and a decrease in the effective barrier height.