利用溶液法在矽基板上成長氧化鋅微奈米柱陣列之研究

Abstract

本論文的研究主要在於探討如何透過溶膠凝膠法搭配水熱法於矽基板上製作出高品質且準直性良好的氧化鋅微奈米柱陣列。在論文之中，首先介紹溶膠凝膠法和水熱法的基本原理，接著透過薄膜的調製來消除依溶膠凝膠法製備之氧化鋅薄膜表面產生之不均勻的條紋現象，而當無條紋的氧化鋅薄膜經一般熱退火處理後，雖然薄膜表面在退火後已無條紋所產生的結晶顆粒現象，但會出現一區一區高底起伏之形貌，所以需再經金層壓制退火處理使其表面的形態在退火完依然保持很平整，使之後成長在其上之氧化鋅微奈米柱陣列都可釣百分之百準直的目的 。最後再藉由改變退火溫度、生長溫度、成長液濃度、成長時間，了解氧化鋅奈米柱成長在退火後很平整之氧化鋅薄膜上的影響，進一步再提升氧化鋅的結晶品質和降低氧化鋅的缺陷放光比。最後再搭配黃光曝光顯影技術或E-beam顯影技術來限制奈米柱成長之位子，但因氧化鋅薄膜單晶排列不整齊且重疊，所以在同一個位子上會有不同方向之微奈米柱成長在同一個位子上，所以我們透過圖形化種子層來觀察種子層在何種尺寸下所成長出來的氧化鋅奈米柱是單根性的。 接著我們以掃描式電子顯微鏡分析氧化鋅薄膜表面的型態在預熱過程和退火過程後所產生的形貌變化，並且在不同退火溫度的氧化鋅薄膜使用不同濃度的生長溶液成長氧化鋅奈米柱。最後再藉由XRD分析和PL分析，探討在鍍金退火完後之非常平整之薄膜表面上所成長奈米柱的尺寸、結晶性及缺陷放光比上和退火溫度、成長條件的關係。透過以上的分析發現，在0.45 M的薄膜依300度預熱後經鍍金退火後所成長出來的奈米柱品質最佳，且經900度鍍金退火一小時後氧化鋅在XRD ( 0 0 2)的peak強度可由500度的44,006提升到75,684，缺陷放光比則由55%降低到20%。接在再藉由調整生長條件從90度100mM成長十小時調整到120度200mM成長十時，可進一步將氧化鋅在XRD(0 0 2)的peak強度從75,684提升到36,3070，缺陷放光比則由20 %降低到9 %

The main goal of this thesis is how to grow the well-aligned and high quality ZnO microrod/nanorod arrays on silicon substrates by solution process. At first, we introduce the basic principles of the sol-gel method and hydrothermal method, and then by using the modulation of the ZnO thin film eliminates the uneven wrinkles of the surface of ZnO thin films prepared by sol-gel method. After thermal annealling, although, the surface of ZnO thin film have no particles appeared around the wrinkles , the morphology of surface appears ups and downs and uneven. Therefore, ZnO films were coated by the gold layer before annealing treatment to eliminate the uneven surface, and the surface of ZnO thin films becomes more uniform and smooth after annealing. Then the ZnO microrod/nanorod arrays grown on that surface have very good collimation. In the following experiments, annealing temperature, concentration of growth, temperature of growth and time of growth were tried to enhance the quality of ZnO microrod/nanorod arrays and reduce the defect density of ZnO microrod/nanorod arrays. Then we can understand the relationship of ZnO thin films and ZnO rods or growing conditions and ZnO rods through these modulations. Finally, optical lithography or E-beam lithography technologies were applied to limiting the position of nanorods/ microrods, achieving orderly-arranged ZnO microrods/nanorods on silicon substrates by solution process. However, the single crystal areas of ZnO thin films overlap, and the ZnO rods appear different directions at one position. In order to solve this phenomenon, we limit the diameter of patterned ZnO thin films to find out what is the smallest diameter of ZnO thin films that can grow single-direction ZnO microrod/nanorod. Then we observe the surface morphology changes of ZnO thin films in the preheating process and annealing process by scanning electron microscope analysis. Finally, XRD analysis and PL analysis were used to explore the relationships among the crystalline and defect ratio of ZnO microrod/nanorod arrays, the annealing temperature of ZnO thin films or the growth conditions of hydrothermal methods. Through the above analysis, the best quality ZnO microrod/nanorod arrays grow on 0.45M ZnO thin film preheated at 300 ℃ and annealed with Au-layer , and the intensity of XRD (0 0 2) peak of ZnO rods enhance from 44006 to 75684, the defect ratio from 55% to 20% as the annealing temperature of ZnO thin films changes from 500 ℃ to 900 ℃. The intensity of XRD (0 0 2) peak of ZnO rods can increase from 75,684 to 36,3070 and the defect ratio of ZnO rods can reduce from 20 % to 9 % by adjusting the growth conditions from 90 ℃,100 mM ,10 hours to 120 ℃, 200 mM, 10 hours.