- 學位論文
超音波霧化熱解法成長YBCO薄膜之研究
The Study of YBCO Thin Films Fabricated by Ultrasonic Spray Pyrolysis
摘要
本論文尋求使用設備簡單與製程容易的超音波噴霧熱解法，在便宜的鈮酸鋰基板上成長超導薄膜。實驗中比較二步驟與單一製程，首先將硝酸釔、硝酸鋇、硝酸銅溶解於去離子水中，再用超音波噴霧系統將先驅物沉積在鈮酸鋰基板上。沉積後之樣品放入高溫爐中作加熱反應，是為二步驟製程，過程中改變反應氣體及溫度成長YBCO薄膜，接著再利用XRD、SEM及四點探針分析結構與電性，找出最佳實驗參數。 二步驟製程當中，實驗發現最佳沉積時間為10分鐘，使用氬氣進行熱反應，不同反應時間將影響超導薄膜的晶相。實驗發現最佳反應時間為80分鐘。 單一製程實驗中，從XRD分析發現，升溫過程中會有其它化合物產生；反應時間的增加，會幫助Y-123往c軸成長。R-T量測分析顯示，薄膜都顯示有超導相變。因此本實驗發現確實可以利用單一製程，在鈮酸鋰基板上成長出具有超導相Y-Ba-Cu-O薄膜。
並列摘要
In this study, two-step and one-step, processes were employed to fabricate YBCO superconducting thin films. Y-Ba-Cu-O thin films were deposited on inexpensive LiNbO3 by using ultrasonic spray technique. First, nitrate solution which includes yttrium nitrate, barium nitrate and copper nitrate was dissolved in DI water. Then, ultrasonic spray system was employed to deposit precursor on the LiNbO3 substrates. Finally, the as-deposited samples were reacted in furnace. The different experiment parameters, reacting atmosphere and reacting temperature, were optimized by XRD、SEM and four-probe measurements results. In two-step process, the reacting atmosphere and reacting temperature affects the YBCO crystalline structure. The 80-min reacting time in argon and the 930℃ reacting temperature had the best result of XRD, R-T and SEM. In one-step process, In the analysis discovered from XRD that will have other compound production in the elevation of temperature process. As reacting time goes up, it helps YBCO grow along the c-axis. The R-T measurement shows that thin films have transition-curve. In this study, Y-Ba-Cu-O thin films were grown on LiNbO3 by using ultrasonic spray pyrolysis with superconducting transition.