本文關(guān)鍵詞： 脈沖激光沉積 YBa_2Cu_3O_(7-x)薄膜 取向生長　出處：《西安理工大學(xué)》2017年碩士論文　論文類型：學(xué)位論文

【摘要】：YBa_2Cu_3O_(7-x)(YBCO)高溫超導(dǎo)薄膜因具有高臨界電流密度、高臨界轉(zhuǎn)變溫度而受到廣泛關(guān)注,并且在高溫超導(dǎo)電子器件領(lǐng)域有著廣泛的應(yīng)用前景,因此高質(zhì)量、高性能YBCO薄膜的制備是超導(dǎo)電子器件應(yīng)用的基礎(chǔ)。 YBCO薄膜具有強(qiáng)烈的各向異性,所以其超導(dǎo)性和生長取向密切相關(guān),而在實(shí)際應(yīng)用中以c軸和a軸取向的超導(dǎo)薄膜為主,其中c軸主要應(yīng)用于電極和涂層導(dǎo)體的制備方面,a軸主要應(yīng)用于對于超導(dǎo)機(jī)制的研究以及約瑟夫森結(jié)的制備方面。但要獲得單一取向生長的YBCO薄膜比較困難,相比于溶膠凝膠法,脈沖激光沉積法具有厚度可控、薄膜均勻致密、可原位沉積多層膜等優(yōu)點(diǎn),所以本文擬采用脈沖激光沉積法來實(shí)現(xiàn)對YBCO薄膜的生長取向的控制,獲得具有單一取向的外延薄膜。首先,通過不同實(shí)驗(yàn)參數(shù)在鋁酸鑭(LaAlO3)單晶基片上沉積了一系列YBCO薄膜。研究發(fā)現(xiàn),沉積溫度和氣壓是影響薄膜取向的主要因素,低溫度、高氣壓下容易生長出a軸取向的YBCO薄膜,高溫度、低氣壓有助于c軸YBCO薄膜的生長,本文在對樣品臺(tái)進(jìn)行加工后得出:在沉積溫度為725℃、氧壓為70Pa條件下可制備出純a軸取向生長的YBCO薄膜:在沉積溫度為850℃、氧壓為1OPa條件下可制備出純c軸取向生長的YBCO薄膜,其臨界轉(zhuǎn)變溫度為67K。其次,引入氬氣作為傳熱介質(zhì)來提高襯底的實(shí)際溫度,有利于氧原子的擴(kuò)散,從而提高臨界轉(zhuǎn)變溫度,得出在沉積溫度為85(T℃、總氣壓為30Pa條件下YBCO薄膜的臨界轉(zhuǎn)變溫度提高至88.57K,較未引入氬氣時(shí)有大幅提高。并嘗試制備不同取向YBCO的多層膜結(jié)構(gòu),通過控制沉積參數(shù)得到底層和頂層均為c軸外延取向,中間層為a軸外延取向的YBCO(c)/YBCO(a)/YBCO(c)結(jié)構(gòu),測試結(jié)果表明成功外延出多層膜結(jié)構(gòu),為后續(xù)基于約瑟夫森結(jié)的超導(dǎo)電子器件的制備奠定基礎(chǔ)。
[Abstract]:YBa2Cu3OC (YBa2Cu3O) high temperature superconducting thin films have received extensive attention because of their high critical current density and high critical transition temperature, and have wide application prospects in the field of high temperature superconducting electronic devices, so they are of high quality. The preparation of high performance YBCO thin films is the basis for the application of superconducting electronic devices. YBCO thin films have strong anisotropy, so their superconductivity is closely related to the growth orientation, while in practical applications, the superconducting films with c-axis and a-axis orientation are the main ones. The c-axis is mainly used in the preparation of electrodes and coated conductors. A axis is mainly used in the study of superconducting mechanism and the preparation of Josephson junctions, but it is difficult to obtain single oriented YBCO thin films. Compared with sol-gel method, pulsed laser deposition method has the advantages of controllable thickness, uniform and compact film, and in situ deposition of multilayer films. Therefore, the pulsed laser deposition method is proposed to control the growth orientation of YBCO thin films. A series of YBCO thin films were deposited on LaAlO3 single crystal substrates with different experimental parameters. It was found that the deposition temperature and pressure were the main factors affecting the orientation of the films. It is easy to grow a-axis oriented YBCO films at high pressure. High temperature and low pressure are helpful to the growth of c-axis YBCO films. In this paper, after processing the sample table, it is concluded that the deposition temperature is 725 鈩，

本文編號(hào)：1540865