Catalyst free N-doped carbon nanotube arrays based on a ZnO nanorod template with high performance field emission

Abstract

Nitrogen doped carbon nanotube arrays (NCNTA) were synthesized by a catalyst-free chemical vapor deposition (CVD) method using ZnO nanorod arrays as a template. The as-prepared NCNT samples, with open-ended morphologies, were characterized by SEM, Raman, TEM, EDS, and XPS analysis. The field emission (FE) properties of the NCNT emitters were investigated and optimized by improving the deposition time of pyridine with a low turn-on field of 0.36 V μm⁻¹ and a high field enhancement factor of 65 199, which are superior to those of CNTs prepared using an anodic alumina oxide template. First-principles calculations indicate that the improved FE performance of the NCNT is attributed highly to the decrease of the work function. In addition, in comparison with the NCNT prepared by the catalyst-support CVD method, the enhancement of the FE performance of the NCNT is mainly due to the higher field enhancement factor. Meanwhile, the current fluctuation of the NCNT sample is about 2.3% at 1.36 mA cm⁻² after 1200 min continuous operation under a pressure of 4.5 × 10⁻⁵ Pa. These results suggest that the NCNT emitter based on the ZnO nanotemplate is promising to develop FE devices.