탄소 나노튜브 위에 붕소 및 탄소 질화 박막이 코팅된 이종접합 구조 미세팁의 전자방출 특성

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 (Imax) at 1kV and turn-on voltage (Von) for approaching 1 µA. The results showed that the Imax current was significantly increased and the Von voltage were remarkably reduced by the coating of CN or BN films. The measured values of Imax-Von were as follows; 176 µA-500V for the 5nm CN-coated emitter and 289 µA-540V for the 2nm BN-coated emitter, respectively, while the Imax-Von of the as-grown (i.e., uncoated) emitter was 134 µA-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.