霧化式化學氣相沉積氧化鋅磊晶薄膜

Abstract

本計畫主要研究新型霧化化學氣相沉積法在藍寶石基板成長 n 型氧化鋅半導體磊晶 薄膜。使用乙醯丙酮鋅前驅物之霧化化學氣相沉積法具有簡易、穩定、低成本、高效率、 無毒等特性，並可混合乙醯丙酮鋁及乙醯丙酮鎵，易於n 型摻雜氧化鋅半導體磊晶薄膜 之沉積。非極性與半極性氧化鋅具有優越之光電特性，可應用於發光元件。 本計畫分三年進行。從霧化系統的建置開始，嘗試各種不同的沉積條件，經由探討 成核與成長的過程與缺陷分析，改進結晶品質，基板則以最常用的藍寶石基板為主，最 終則在非極性與半極性氧化鋅單晶基板上成長摻雜鋁及鎵之磊晶薄膜。第一年建置前驅 物超音波霧化系統，並於a面藍寶石基板成長c面氧化鋅，同時試驗摻雜鋁及鎵之n型半 導體效果。第二年進行c面氧化鋅摻雜鋁及鎵之最佳化條件，並沉積非極性氧化鋅於r面 與m面藍寶石基板，也評估成長半極性氧化鋅薄膜的可行性。第三年進行非極性與半極 性氧化鋅摻雜鋁及鎵於之最佳化條件。 計畫利用電子顯微鏡、X 光繞射、二次離子質譜等材料分析技術研究薄膜成長過 程、磊晶關係、摻雜濃度與晶體缺陷，並測量薄膜摻雜後之電子遷移率及載子濃度，研 究影響電性之因子。

A novel chemical vapor deposition (CVD) method using mist of precursors will be developed to grow n-type epitaxial zinc oxide (ZnO) films on sapphire substrate. This mist-CVD with precursor of zinc acetylacetonate is simple, stable, and nontoxic with low-cost, high-efficiency. As zinc precursor can easily mix with aluminum (Al) and gallium (Ga) acetylacetonates, it is beneficial for ZnO deposition with n-type doping of Al and Ga. Nonpolar and semipolar ZnO possess better optoelectronic properties than polar ZnO, which can be useful for light-emitting devices. The project is proposed to carry out for three years. The study starts from setting up a mist apparatus, and various deposition conditions for growth of ZnO on sapphire will be tried to find out an optimized CVD condition through film characterization which allows understanding the growth mechanism and improves the film quality. Finally, epitaxial ZnO doped with Al or Ga will be deposited on single crystalline ZnO substrate to explore the doping effects on properties of n-type semiconductor including electron mobility and carrier concentration. The first year will focus on the mist system with precursors, and growth of ZnO on a-plane sapphire. Also preliminary doping experiments will be carried out. In the second year, optimized growth of c-plane ZnO doped with Al and Ga will be the task, followed by growth of nonpolar ZnO on r-plane and m-plane sapphire substrates. Deposition of semipolar ZnO will be evaluated. Third year will focus on doping of nonpolar and semipolar ZnO. Material analytical techniques of electron microscopy, x-ray diffraction, and secondary ion mass spectroscopy will be utilized to study the growth of ZnO film, the doping effect, defects. Also, the relationship of electron mobility and carrier concentration with film microstructure will be studied as well.