Masao Urayama

Silicon Field Emitter Capable of Low Voltage Emission

A silicon field emitter of a very low voltage emission type has been obtained. In this emitter, a thermal SiO 2 film was used as an insulator which separates the gate electrode from the cathode substrate. It is easy to decrease the distance between the gate electrode and the emitter by thermal oxidation and oblique deposition process. In this field emitter, in spite of 3 μm diameter of initial mask size, we were able to obtain a 400 nm gap which is the distance between the gate electrode and the emitter tip. Therefore, the onset of emission was established at gate voltages as low as 10 V with Fowler-Nordheim-like emission characteristics. Then anode current was 2.5 μA at 25 V in one emitter and transconductance (g m =ΔIA/ΔVG) was 0.5 μS

Improvement of Field Emission Characteristics by Fabricating Aligned Open-Edged Particle-Free Carbon Nanotubes.

We have developed a process to thin the tips of the aligned carbon nanotubes grown by the microwave plasma enhanced chemical vapor deposition. In the process, an oxygen-plasma oxidation treatment was performed at first to reduce the thicknesses of the nanotubes, and a magnetic-force particle-drawing treatment was then performed to remove the catalyst particles capped on the tops of the nanotubes. Scanning and transmission electron microscopy images of thus treated nanotubes show that the average radius of curvature at the tips has been reduced by over 50% of that of the as-grown nanotubes and most of the catalyst particles have been successfully removed. The field emission characteristics of the open-edged particle-free nanotubes show that the turn-on voltage has been reduced by 23% of that of the as-grown nanotubes.