- 學位論文
含氮奈米晶鑽石膜之光電特性及在太陽能電池之應用
Optoelectronic Properties of Nitrogen-Doped Nanocrystalline Diamond Films and Solar Cell Applications
摘要
鑽石本身具有許多優異的物理與化學複合特性，因此被喻為下個世代的半導體材料，但是一般CVD所合成的微米晶鑽石膜(Microncrystalline diamond films, MCD films)，除了表面刻面(Facet)造成粗糙度過大以外，MCD膜不易透過摻雜提高其半導體特性，是MCD膜無法導入半導體應用的最大問題。因此，本論文將使用自組裝之微波電漿束化學氣相沉積系統合成奈米晶鑽石膜(Nanocrystalline diamond films, NCD)，並且透過氮元素之摻雜形成含氮奈米晶鑽石膜(NCD:N films)，提升NCD膜之半導體特性。製程中討論電漿中氮氣濃度對薄膜之結構、光學、電性及薄膜基本性質之影響，並且將NCD:N膜複合p-type矽晶圓做成NCD:N/p-Si太陽能電池，並探討其太陽能電池之特性。研究中發現薄膜之表面微結構、粗糙度、薄膜內部結構、N/C比值、電性及光學性質，均明顯受到氮元素摻雜之影響。 研究結果發現隨著氮氣摻雜量越多，薄膜表面的團聚現象伴隨著電漿中CN物種的濃度增高而提升，其薄膜表面粗糙度為Rms:16.5 nm ~ 20.4 nm，潤濕性隨之增加(接觸角 94.4° ~ 64.6°)，光學穿透率則是隨著氮氣的增加而有降低的趨勢(87% ~ 72%)，霍爾量測顯示載子濃度經由氮元素之摻雜可有效提升2 級數，由1016 cm-3提升至1018 cm-3。 利用NCD:N復合p-type矽晶所製作之太陽能電池元件，其光電轉換效率為2.8%，開路電壓為0.52 V，短路電流為3 mA，填充因子為0.38。
並列摘要
Diamond is called the semiconductor material in next generation owing to the outstanding composite physical and chemical features. However, the roughness of CVD-composited MCD films was large due to the surface facet. Additionally, the main problem is that the properties of semiconductor were hard to improve through the doped MCD films. Therefore, the nanocrystalline diamond films (Nanocrystalline diamond films, NCD) was composited by the self-assembly microwave plasma-jet chemical vapor deposition system in this research. The semiconductor properties of NCD film were improved by nitrogen doping. The structure, optical, electrical and basic film properties were discussed with the nitrogen ratio of the plasma. The NCD:N/p-Si solar cell was compounded by NCD:N film and p-type silicon wafer and the properties were discussed. The results of this research showed that the micro structure, roughness, internal structure of the film, N/C ratio, electrical properties, and optical properties were affected by the nitrogen doping. Additionally, the agglomeration of the film was increased with the higher concentration of CN species when the ratio of doped nitrogen was increased. The roughness of the film was Rms:16.5 nm ~ 20.4 nm and the wettability was increased (contact angle 94.4° ~ 64.6°). The optical transmittance was decreased (87% ~ 72%) with the higher nitrogen. The results of Hall measurements showed that the carrier concentration increased 2 order (1016 cm-3 to 1018 cm-3) through nitrogen doping. The solar cell was made by NCD: N compound with p-type silicon. The photoelectric conversion efficiency was 2.8%. The open-circuit voltage was 0.52 V. The short-circuit current was 3 mA and the fill factor was 0.38.