中文摘要
本論文利用分子束磊晶系統蒸鍍五環素(pentacene)，並摻雜不同濃度的鎳(Ni)，來探討以塊材相的pentacene的2p軌域與Ni的3d軌域耦合來作為磁性傳遞橋樑下的物理特性。實驗上，先利用本實驗室的相溶劑轉變技術使預先蒸鍍在基板上的pentacene之薄膜相(thin-film phase)轉為塊材相(bulk phase)，使接續共蒸鍍Ni的pentacene為具塊材相的薄膜，藉此來提高pentacene分子間電子耦合(electron coupling)。
從XRD的量測結果可以得知，pentacene由原本的薄膜相轉變為塊材相，但隨著Ni摻雜濃度的提高，pentacene的薄膜相訊號又逐漸增強，因此我們可以得知Ni的摻雜濃度提高時會降低pentacene分子之間的電子耦合。又由paracrystal理論分析得知，塊材相的pentacene其crystalline size、disorder、tilt angle並不會因為Ni得摻雜濃度提高而有明顯的變化。另外由AFM圖中我們可以得知，當Ni的摻雜濃度提高時，會使晶粒有逐漸變大的趨勢且呈現不規則的區域性分佈。
從偏極化拉曼激發光譜中我們發現隨著Ni的摻雜量提高，pentacene的拉曼激發光譜有藍移的趨勢，表示pentacene分子間的耦合程度下降，原因為Ni摻雜濃度提高時，使pentacene的薄膜相逐漸提高造成分子間的耦合程度下降，因此造成藍位移。然而我們外加垂直磁場(3000 Oe)後，拉曼激發光譜隨著Ni的含量提高又有紅移的趨勢，表示pentacene分子間的耦合程度上升，原因為外加磁場使pentacene的2p軌域和Ni的3d軌域的耦合程度提升，進而使分子振動不易，因此造成振動光譜紅位移。
在超導量子干涉儀的分析當中，pentacene與Ni的摻雜比例大於1:0.25時，矯頑力開始呈現線性的增加，且從不同Ni摻雜濃度下的M-T圖當中，我們可以觀察出磁化量隨著溫度變化的物理特性。在零場冷卻的曲線[zero-field-cooled (ZFC) curve]中，我們可以發現溫度由3K上升至25 K時，磁化量因為磁矩受到熱擾動的干擾而逐漸減小。但在溫度大於25 K後磁化量逐漸升高，原因為Ni的磁性傳遞藉由著pentacene的2p軌域和Ni的3d軌域彼此間耦合的橋樑來感應，因此磁化量不會因為熱擾動的關係而下降，反而逐漸上升。在加場冷卻的曲線[field-cooled (FC) curve]中，磁矩因為熱擾動的干擾減少而使磁化量逐漸上升，而當溫度下降至100 K時，磁矩幾乎轉為同方向因此磁化量開始急速上升。

Abstract
We studied the physical property of the intermolecular electron coupling between the 2p orbit of pentacene and 3d orbit of Ni, called “magnetic transmission bridge”, in different concentration of Ni-doped pentacene thin films. First, we used organic solvent (chlorobenzene, CB) to make a phase transformation from thin-film phase to bulk phase for beforehand deposited pentacene film. This process keeps the bulk phase on later deposited Ni-doped pentacene film to enhance intermolecular electron coupling. Second, we coevaported pentacene and Ni by molecular beam expitaxy (MBE).
Polymorphic phase transformation within pentacene films could be examined by x-ray diffraction (XRD). The result showed that a phase transformation from the thin-film phase to the bulk phase occurs after solvent annealing process. The intensity of XRD peak of the thin-film phase increased with increasing Ni-doping concentration, indicating that the intermolecular electron coupling of pentacene decreased with increasing Ni concentration. Based on the calculations by paracrystal theory, crystalline size, disorder, and molecular tilt angle in pentacene film were almost unchanged when increasing Ni-doping concentration. Besides, the pentacene grain became larger and irregular distribution with increasing Ni-doping concentration.
To study the electron coupling of pentacene molecules further, Raman spectroscopy measurements were performed on Ni-doped pentacene film. The blue-shift level of peak at 1155cm-1, which corresponds the vibration hydrogen atom located at both ends of the pentacene, increased with increasing Ni-doping concentration. This indicates that the thin-film phase pentacene easily formed at higher Ni-doping concentration to result in the decrease of intermolecular electron coupling. When a magnetic field (3000 Oe) was applied on Ni-doped pentacene film, the Raman peak became red shift due to the increase of intermolecular electron coupling by overlap of the 2p orbit of pentacene and the 3d orbit of Ni.
Coercivity of Ni-doped pentacene thin film increased linearly when the ratio of pentacene to Ni was above 1:0.25. Moreover, the variation of magnetic moment at different temperatures could be obtained from the magnetization-temperature (M-T) curvee. According to the result of the zero-field-cooled (ZFC) curve, magnetic moment decreased when the temperature increased from 3 K to 25 K because the magnitude of the magnetic moment of the equivalent dipole was decreased by thermal disturbance. As the temperature was above 25 K, magnetic moment increased gradually owing to the increase of “magnetic transmission bridge” of pentacene molecules. Then, the field-cooled (FC) curve was measured. The magnetic moment increased because of the reduction of thermal disturbance. When the temperature was dropped to 100 K, magnetic moment increased quickly because the direction of the magnetic dipole moment of each Ni atom was turned to the same direction.

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