| Title |
Electron Emission Properties of Hetero-Junction Structured Carbon Nanotube Microtips Coated With BN And CN Thin Films |
| Authors |
노영록(Noh, Young-Rok) ; 김종필(Kim, Jong-Pil) ; 박진석(Park, Jin-Seok) |
| Keywords |
Carbon Nanotubes ; Microtip X-Ray Electron Source ; Amorphous Boron Nitride ; Amorphous Carbon Nitride ; Field Emission ; Long-Term Stability |
| Abstract |
Boron nitride (BN) and carbon nitride (CN) films, which have relatively low work functions and commonly exhibit negative electron affinity behaviors, were coated on carbon nanotubes (CNTs) by magnetron sputtering. The CNTs were directly grown on metal-tip (tungsten, approximately 500nm in diameter at the summit part) substrates by inductively coupled plasma-chemical vapor deposition (ICP-CVD). The variations in the morphology and microstructure of CNTs due to coating of the BN and CN films were analyzed by field-emission scanning electron microscopy (FE-SEM). The energy dispersive x-ray (EDX) spectroscopy and Raman spectroscopy were used to identify the existence of the coated layers (CN and BN) on CNTs. The electron-emission properties of the BN-coated and CN-coated CNT-emitters were characterized using a high-vacuum field emission measurement system, in terms of their maximum emission currents (I_{max}) at 1kV and turn-on voltage (V_{on}) for approaching 1μA. The results showed that the I_{max} current was significantly increased and the V_{on} voltage were remarkably reduced by the coating of CN or BN films. The measured values of I_{max}-V_{on} were as follows; 176μA-500V for the 5nm CN-coated emitter and 289μA-540V for the 2nm BN-coated emitter, respectively, while the I_{max}-V_{on} of the as-grown (i.e., uncoated) emitter was 134μA-620V. In addition, the CNT emitters coated with thin CN or BN films also showed much better long-term (up to 25h) stability behaviors in electron emission, as compared with the conventional CNT emitter. |