Field emission from flat graphene sheets is a challenge due to fewer emission sites. Here, we have synthesized free-standing vertically oriented few-layer graphene (FLG) films directly on dielectric substrates by hot-filament chemical vapor deposition (HFCVD) without any catalyst or special substrate treatment. The fabricated FLGs with a large smooth surface topography, standing roughly vertical to the substrate are found to grow according to the Stranski–Krastanov growth mechanism. The ease of large-area preparation and the low turn-on field of 22 V µm−1 in addition to the large field enhancement factor of ≈6520 for electron field emission suggest that the vertically oriented FLGs could be used as a potential edge emitter.
Scanning electron microscopy image of vertically oriented few-layer graphene on a SiO2/Si substrate with the schematic of field electron emission.