碳嵌入奈米晶鑽石薄膜及其電子場發射性質

鑽石薄膜由於其優異的物理及化學特性，被視為極具潛力的場發射陰極材料。它的場發射行為近年被廣泛的研究，從文獻資料可以大致歸納出幾個重要的影響因素。例如鑽石晶粒的大小，晶界的比例，薄膜導電度，鑽石的缺陷結構，表面官能基，表面粗糙度等等。本研究發現在薄膜成核過程先行添加奈米石墨纖維，將有助於提升鑽石薄膜成長後的場發射性質。這種薄膜的起始電場達到 4.4 V/μm ,且在7 V/μm 的電場下有0.06 mA/cm2 的電流密度。這種薄膜由於石墨的添加而提升了導電性，並且產生缺陷能帶讓電子場發射更加容易。薄膜中石墨與鑽石的連接還可使薄膜功函數降低，進而降低場發射的起始電場。本研究針對碳嵌入奈米鑽石薄膜的電子場發射行為進行深入探討。先以場發射掃描式電子顯微鏡和原子力顯微鏡觀察鑽石薄膜表面的形貌及粗糙度。用拉曼光譜儀，X光繞射分析儀，X光光電子能譜儀和穿透式電子顯微鏡觀察其結構，再用四點探針和陰極激發光譜儀量測其導電度和發光特性，最後以自組裝二極式場發射系統量測薄膜的場發射性質。未來可以調整鑽石薄膜在微波電漿輔助化學氣相沈積成長的製程參數，將其性質最佳化，讓它更符合場發射陰極材料實際應用的需求。

關鍵字

場發射；鑽石；石墨；奈米；化學氣相沉積

並列摘要

Diamond film has attracted immense attention as a field emission material due to its negative electron affinity and robust mechanical and chemical properties. It has been widely investigated. Based on literatures, the critical factors of diamond film field emission are grain size, the structure of grain boundary, conductivity, graphite structure distribution, structural defect density, surface roughness, surface functional groups, etc. In this work, nano-graphite fiber embedded nano-crystalline diamond films were synthesized, and it’s excellent electron field emission properties were studied. The nano-graphite fiber embedded nano-crystalline diamond film can be turned on at a low field as 4.4 V/μm and attain large field emission current density about 0.06 mA/cm2 at 7 V/μm applied field. The embedment of nano-graphite increased the conductivity of the film, and lowered the work function of nano-crystalline diamond film. The defects in the diamond structure created additional energy levels in the diamond band structure, which induced electron emission at low electric fields. The morphology and surface roughness of carbon embedded nano-crystalline diamond films were studied by field emission scanning electron microscope (FESEM) and AFM. Raman, XPS, XRD, TEM, CL are used to investigate the microstructure of the films. Conductivity and field emission properties were measured by four point probe and homemade field emission system respectively. In the future, the parameters of MPECVD grown nano-crystalline diamond film were further optimized to get better field emission cold cathode materials.

並列關鍵字

Field Emission ； Diamond ； Graphite ； Nano ； CVD

參考文獻

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碳嵌入奈米晶鑽石薄膜及其電子場發射性質

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