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Electron Emission Properties of Hetero-Junction Structured Carbon Nanotube Microtips Coated With BN And CN Thin Films

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

  • 노영록 (한양대 전자전기제어계측공학과) ;
  • 김종필 (한양대 전자전기제어계측공학과) ;
  • 박진석 (한양대 전자컴퓨터공학)
  • Received : 2010.01.21
  • Accepted : 2010.03.08
  • Published : 2010.04.01

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 $1{\mu}A$. 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; $176{\mu}A$-500V for the 5nm CN-coated emitter and $289{\mu}A$-540V for the 2nm BN-coated emitter, respectively, while the $I_{max}-V_{on}$ of the as-grown (i.e., uncoated) emitter was $134{\mu}A$-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.

Keywords

Carbon Nanotubes;Microtip X-Ray Electron Source;Amorphous Boron Nitride;Amorphous Carbon Nitride;Field Emission;Long-Term Stability

Acknowledgement

Supported by : 한국학술진흥재단

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