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    Title: 半導體薄膜沉積成長過程之動力蒙地卡羅方法探討
    Other Titles: The investigation of thin film growth process with semiconductor materials: a kinetic monte carlo study
    Authors: 林奕君;Lin, Yih-jiun
    Contributors: 淡江大學化學學系博士班
    王伯昌;Wang, Bo-cheng
    Keywords: 動力蒙地卡羅;階梯流動效應;半階寬;擴散長度;轉移溫度;沉積速率;kMC;thin film growth;diffusion length;step-width effect;transition temperature;step-flow growth;Alq3;deposition rate
    Date: 2008
    Issue Date: 2010-01-11 02:47:43 (UTC+8)
    Abstract: 薄膜技術在現代的材料科學中佔有重要的地位,在許多高科技元件製程中薄膜成長條件之控制更是其關鍵技術,因此薄膜結構和性質的基礎研究以及相關製造技術的研發已經成為現今學術界及產業界的重要研究課題。在本論文中,主要使用蒙地卡羅方法,並藉由引進亂數統計機率之概念探討兩種表面成長的現象。
    在本研究的第一部分(第五章)—探討半導體階梯表面上的成長過程。利用與溫度相關之擴散長度R和半階梯寬度(L/2)的大小關係來預估Tc值,並可以依據Tc來預測階梯流動成長之現象。當表面上的溫度低於Tc時,半導體表面階梯流動成長現象中容易發生的step-bunching將不會發生。當階梯系統處於轉移區間時,階梯寬度效應對於階梯流動成長的影響最大。而當溫度遠高於Tc時,表面上的成長模式完全屬於全面性之階梯流動成長,因此在半導體表面的step-bunching現象將會非常明顯。
    而在本研究的第二部分(第六章)—探討沉積速率效應對Alq3沉積結果之影響。當薄膜成長速率小於1.1Å/sec時,表面生長是屬於島狀生長,表面上長條狀之島狀結構明顯。而當沉積速率高於3Å/sec時,表面生長屬於隨機沉積生長,過快的沉積速率導致薄膜表面粗糙度以及內部的空洞率大幅上升。而當沉積速率介於1.1 Å/sec~3 Å/sec時,適量的加快沉積速率可以使薄膜表面上島狀結構逐漸消失並改善薄膜表面的均勻度,對於電子發光裝置效率來說應為最佳的沉積速率之結果。
    Applying Kinetic Monte Carlo (KMC) technique, we investigated the influence of temperature and step-width on the step-flow growth of a (2D+1) semiconductor-like uniform-spacing stepped model with inverse Ehrlich-Schwoebel (iES) barrier (chapter 5, part I) and the effect of deposition rate on the growth pattern of the Alq3 thin film (chapter 6, part II). In the part I, the relation between diffusion length (R) and half of step width (L/2) was established to characterize the transition temperature Tc for switching between the random deposition growth and step-flow growth on surface. When temperature is lower than Tc, the surface growth mode is dominated by random deposition growth. As temperature approaches to Tc, the surface growth mode gradually switches to step-flow growth. However, only when the temperature is much higher than Tc, the random deposition growth is completely replaced by the step-flow growth. It is found that the step-width effect has a profound influence on surface growth mode in the transition region.
    In the part II, we successfully investigated the effect of deposition rate on the growth pattern of the Alq3 thin film. In a good agreement with experimental results, our simulation results indicate that there exists a transition growth in terms of the deposition rate corresponding to the transition between the island growth and random deposition growth. In the island growth (deposition rate is lower then 1.1 Å/s) and random deposition growth (deposition rate is higher then 3 Å/s) region, the surface morphology is insensitive to the increasing in the deposition rate. Within the transition growth region (deposition rate is between 1.1 Å/s and 3 Å/s), the homogeneity of film surface improves as the deposition rate increases. Not only the pattern of the island structures becomes blurred but also the inner vacancy ratio and surface roughness remain in low values as the deposition rate increases. From our results, there may exist a deposition rate to optimize the Alq3 film suitable for the luminant devices.
    Appears in Collections:[Graduate Institute & Department of Chemistry] Thesis

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