Carbon nanotube integrated on silicon tips for electron field emitter: Tip apex patterning and emission characterization

In this work, we developed a selective patterning and lift-off technique for synthesis and patterning of carbon nanotube (CNT) at the apex of a silicon tip. Purpose of this work is to improve the throughput and yield rate of forming CNT at the silicon tip as electron field emitters. The sharp silicon micro-tip were formed by an ICP-RIE dry etching and wet etching in a TMAH solution. After thermally oxidation at 950°C and selective etching in a buffer-HF (BHF) solution, a sharp silicon tip was formed at the center of a small silicon oxide aperture. CNTs were entirely grown over the tip by a Hot Filament-Chemical Vapor Deposition (HF-CVD) using Fe as a catalyst. After removing of the sacrificial silicon oxide layer in the BHF solution, small size CNTs bundles were remained at the apex of the silicon tip. The emission properties of the grown individual and bundle CNT at the Si tip were measured, and compared with a single silicon tip. The threshold voltage of the individual CNT was found to be 4V/μm, that is 5 times lower than that of the silicon tip. Emission pattern of the bundle CNT/Si tip was observed using a phosphor anode screen (ZnO, Zn).