- 學位論文
以奈米鑽石的表面改質來提高鑽石薄膜之成核並應用於紫外光感測器
Surface modification of nanodiamond particles for nucleation enhancement in diamond film growth toward application of UV detector
摘要
奈米鑽石本身擁有極為優異的材料特性，像是高穿透性、高熱傳導性與優異的化學惰性等，不論是物理還是化學性質，都是許多材料無法比擬的，因此被認為具有極高的應用潛力，所以本研究利用實驗室自組裝之微波電漿束化學氣相沉積(MPJCVD)系統沉積奈米晶鑽石(NCD)薄膜，製程具有大面積、低成本操作方便與不受環境限制等優點。 研究中先利用氫電漿對奈米鑽石粉末進行表面改質處理，來提高奈米鑽石粉末之分散性，過程中探討改變工作壓力及微波功率的影響，並利用表面形貌與微結構特性檢測進行分析，再將最佳分散參數之鑽石粉末依特定比例所調成的鑽石溶液，透過簡單且快速之前處理-旋轉塗佈法(Spin coating)旋塗於基板後利用MPJCVD系統進行奈米鑽石薄膜的成長。發現所成長之奈米鑽石膜晶粒大小為32 nm，具有低粗糙度(rms~29.3 nm)、高sp3含量(76.1 %)與潤濕性(106ﾟ)。 再將製備好的NCD薄膜透過微影製程與濺鍍技術製作出UV感測器並進行光電特性之探討，過程中比較金薄膜與ITO薄膜之指叉狀電極所製作出的紫外光感測器，發現ITO電極因為具有良好導電性與高透光性，能有相較於金電極還高的時間響應，且經過400℃退火處理後不但時間響應有提高(2.4 order)，也獲得線性的電流-電壓曲線達到良好的歐姆接觸，將測量次數與測量時間拉長發現其亦具有優異的穩定性與再現性，相信此研究中製作之紫外光感測器的應用在光電產業中深具潛力。
並列摘要
In last decades, nanodiamonds have attained much interests because of their own unique characteristics given by intrinsic diamond and low-dimensional structures including of unrivalled hardness, highly chemical inertness, high thermal conductivity, optical transmittance, good biocompatibility, and so forth. This study presents a complete fabrication process of NCD films using microwave plasma jet chemical vapour deposition (MPJCVD) technique with low manufacturing cost, large deposition area, easy to operate, and friendly with environment. Hydrogen plasma was first employed for surface modification of nanodiamond particles (NDPs) aiming at their stable suspension for further seeding nucleation procedure. The effects of microwave power and working pressure on microstructure, surface characteristics, and dispersion of NDPs in methanol were investigated. The seeding nucleation using spin-coating technique with the as-prepared diamond suspension was found to ensure highly uniform and high nucleation density on the substrate surface. Also, the NCD films deposited by the MPJCVD technique possessed low surface roughness (rms ~ 29.3 nm), high sp3 fraction (~ 76.1 %), good wettability (contact angle with water of 106o), and uniform diamond crystallite size of 32 nm. In second stages of this study, the as-prepared NCD film was then used for UV irradiation detector. In order to investigate the effects of electrode materials on the performance of diamond-based UV detector, intedigitated Au and indium-tin oxide (ITO) electrodes were deposited onto the surface of NCD films by a nanolithography and sputtering techniques. The photoconductivity measurements shown that UV detector using NCD/Au and NCD/ITO revealed high performance with fast photoresponse, high repeatability and reproducibility. Moreover, the NCD/ITO structure was found to have better photoconductivity which achieved photo-dark current ratio of 2.4 orders. The achievement of our present study indeed open up a prospect application of NCD films in UV detector, photo catalyst, etc.