微波電漿輔助化學汽相沈積法合成鑽石膜
機制探討及場發射特性之研究

本論文研究以微波電漿輔助化學氣相沈積法（MPECVD），在甲烷/氬氣電漿中加入氫氣(甲烷/氬/氫=1/99-X/X)成長鑽石薄膜，結合穿透式電子顯微鏡(TEM)、掃瞄式電子顯微鏡(SEM)及即時電漿放射光譜(OES)，對鑽石薄膜特性及成長機制深入研究。第二部分，我們採取一種修改的成長薄膜方式，在矽(Si)基板成長UNCD作為核層來代替偏壓輔助成核過程，再以甲烷/氫氣電漿於UNCD核層上成長微米鑽石薄膜(MCD/UNCD/Si)，由於其異於一般的電子場發射特性，因此我們設計了一個實驗以試圖找出其原因。研究中發現，我們對於在甲烷/氬氣電漿中加入氫氣，即使氫氣含量為0.1%也會使薄膜樣品上鑽石晶粒由圓形改變為片狀結構，並由OES顯示，微結構的形成，是經由鑽石表面碳氫化合物的黏附與侵蝕之間的競爭所造成的結果，而造成此差異的原因則是視腔體中氫氣電漿的活性決定，而氫氣電漿侵蝕鑽石表面碳氫化合物的想法，在第二部分以甲烷/氫氣電漿於UNCD核層上成長微米鑽石薄膜的方式中，此機制也扮演主要的角色，以致能造成如此特殊的成長方式及異於一般的場發射特性，相信由於這個機制的瞭解，將可以引導出更多的變化及鑽石薄膜特性的進步。

關鍵字

電子場發射特性；成長機制；穿透式電子顯微鏡

並列摘要

The modification on microstructure of diamond films due to the incorporation of H2 species into the Ar/CH4 ((CH4/Ar/ H2=1/99-X/X)) plasma was systematically investigated. How the characteristics of plasma modified the microstructure and the electron field emission properties of the diamond films were investigated using transmission electron microscopy. The possible mechanism for the modification of microstructure was discussed. Micron-crystalline diamond (MCD) films with a unique microstructure were synthesized using a modified nucleation & growth process, in which a thin layer of ultrananocrystalline diamond (UNCD) was used as nucleation layer for growing diamond films in H2-plasma. This modified nucleation and growth process was adopted so as to improve the electron field emission (EFE) properties of diamonds films. From study imply clearly that the transition in microstructure has already been initiated when only 0.1% H2 was incorporated into Ar-plasma. Large spherical clusters (plate grains), around 30 nm in size, were observed for UNCD01 films different from equi-axed geometry for D0 samples (UNCD). Optical emission spectroscopies indicated that addition of H2-species in the Ar/CH4 plasma lead to the decrease in CH-species and increase in atomic hydrogen species. The H2 containing plasma can partially etch away the hydrocarbons (trans-polyacetylene) adhered onto the diamond clusters such that the active-carbon-species in the plasma can attach to diamond surface anisotropically, forming plate diamond grains. The amount of plate-like grains increased with the H2-content in the plasma and evolved into dendrite geometry. In contrast, when H2 is increased, the proportion of atomic hydrogen is abundant and the plasma temperature of hydrogen species is high, so that the atomic hydrogen is very active and can efficiently etch the hydrocarbons adhered on the surfaces of diamonds. The C2-species can thus attach to the surface of diamonds, forming sp3-bonds, and enlarge the diamond grains isotropically. In the second part, by the same mechanism, thus obtained (MCD)UNCD diamond films consist of nano-sized diamond clusters surrounding the large diamond grains and exhibiting better electron field emission (EFE) properties than the conventional diamond materials with faceted grains.

並列關鍵字

electron field emission properties ； growth mechanism

參考文獻

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微波電漿輔助化學汽相沈積法合成鑽石膜機制探討及場發射特性之研究

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