- 學位論文
以脈衝雷射沉積法在氧化鋅上成長氧化亞銅薄膜
Pulsed Laser Deposition of Cuprous Oxide on Zinc Oxide
摘要
Cu2O為一優越的p型半導體材料，在可見光區有很大的吸收係數，可應用於太陽能電池上，但由於n型摻雜不易，許多將Cu2O沉積在異質介面上的研究不斷出現。ZnO為一n型半導體，且為一個被普遍研究的材料，再加上Cu2O(111)方向的晶格排列方式與ZnO(0001)方向的晶個排列方式相近，此時晶格不匹配度只有7.1%，因此將Cu2O沉積於ZnO上並期望Cu2O會沿著ZnO(0001)方向沉積。 本論文是利用脈衝雷射沉積法(pulsed laser deposition，PLD)在氧化鋅上成長氧化亞銅薄膜，以一系列的參數探討氧化亞銅在氧化鋅上的結晶性及其特性。本實驗所使用的雷射光源為Nd：YAG雷射，透過晶體將四倍頻266nm波長輸出，脈衝頻率為10Hz，脈衝寬度＜10ns。首先先在C面藍寶石基板成長一層厚度約15nm的氧化鋅緩衝層，所使用的靶材為自製的氧化鋅靶；接著在氧化鋅上成長氧化亞銅薄膜，所使用的靶材為自製的氧化亞銅靶。 根據實驗結果在特定參數下，在氧化鋅上成長出單晶的Cu2O薄膜，結晶方向也如預期的為(111)方向且為單晶的Cu2O薄膜，並透過穿透光譜轉換成吸收係數進而定義吸收能隙為2.45電子伏特。
並列摘要
Cu2O , a p-type semiconductor, which has high absorption coefficient in visible regions, has potential in solar cells applications. Since n-type doping is difficult to Cu2O, many researches on heterojunctions are found in order to apply Cu2O. ZnO, a well-known n-type semiconductor, seems to be a good candidate. ZnO (0001) and Cu2O (111) orientations have similar arrangements with lattice mismatch calculated to be 7.1%. The Cu2O thin films were deposited by pulsed laser deposition on the ZnO, and discussing the characteristics of Cu2O thin films with series of parameters. The Nd:YAG Q-switched laser with 266nm wavelength was used for ablation. First, ZnO buffer layers with thickness about 15nm were deposited on C-sapphire substrates. The ZnO targets were made by pressed ZnO sintered under high temperature. Then, Cu2O thin films were grown on the ZnO buffer layers. The Cu2O targets were made by pressed CuO pellet which was sintered under high temperature and oxygen-free condition. Due to the experiment results, single phase Cu2O crystals were deposited on ZnO along the expected (111) orientation. The absorption band gap, defined by absorption coefficient which was obtained trough transforming the transmittance, was 2.45eV.