▎ 摘　　要

Carbon materials like nanotubes and graphene have been previously used for field emission application due to their high emission currents and low turn-on voltages. However, in most cases, these devices show low reliability and poor endurance after a few hours of testing. The poor performance is usually attributed to lack of alignment, poor structure quality, and/or non-conformal coating. In this paper, a hybrid structure of graphene-silicon nanorod arrays (NRAs) was demonstrated by direct growth of self-crystallized graphene with Ni vaporassisted growth via a conventional chemical vapor deposition (CVD) system. By carefully adjusting parameters and reducing the deposition rate, thicknesses of graphene layers can be systematically coated in a controllable manner, even on high aspect ratio surfaces such as aligned silicon NRAs. Detailed surface morphologies and microstructures of the graphene-NRAs core-shell hybrid structures were investigated. Findings in field emissionmeasurements indicate that the graphene coating exhibits a remarkable enhancement by lowering the turn-on field, increasing the current density over 4 orders of magnitude, and greatly improving the endurance. The endurance test shows a stable current density of 1000 mu A cm(-2) after more than 15 hours of operation under a constant applied high bias stress.