脉冲激光沉积法制备取向性钇钡铜氧薄膜的研究

发布时间：2018-02-27 03:12

  本文关键词： 脉冲激光沉积 YBa_2Cu_3O_(7-x)薄膜 取向生长　出处：《西安理工大学》2017年硕士论文　论文类型：学位论文

【摘要】：YBa_2Cu_3O_(7-x)(YBCO)高温超导薄膜因具有高临界电流密度、高临界转变温度而受到广泛关注,并且在高温超导电子器件领域有着广泛的应用前景,因此高质量、高性能YBCO薄膜的制备是超导电子器件应用的基础。 YBCO薄膜具有强烈的各向异性,所以其超导性和生长取向密切相关,而在实际应用中以c轴和a轴取向的超导薄膜为主,其中c轴主要应用于电极和涂层导体的制备方面,a轴主要应用于对于超导机制的研究以及约瑟夫森结的制备方面。但要获得单一取向生长的YBCO薄膜比较困难,相比于溶胶凝胶法,脉冲激光沉积法具有厚度可控、薄膜均匀致密、可原位沉积多层膜等优点,所以本文拟采用脉冲激光沉积法来实现对YBCO薄膜的生长取向的控制,获得具有单一取向的外延薄膜。首先,通过不同实验参数在铝酸镧(LaAlO3)单晶基片上沉积了一系列YBCO薄膜。研究发现,沉积温度和气压是影响薄膜取向的主要因素,低温度、高气压下容易生长出a轴取向的YBCO薄膜,高温度、低气压有助于c轴YBCO薄膜的生长,本文在对样品台进行加工后得出:在沉积温度为725℃、氧压为70Pa条件下可制备出纯a轴取向生长的YBCO薄膜:在沉积温度为850℃、氧压为1OPa条件下可制备出纯c轴取向生长的YBCO薄膜,其临界转变温度为67K。其次,引入氩气作为传热介质来提高衬底的实际温度,有利于氧原子的扩散,从而提高临界转变温度,得出在沉积温度为85(T℃、总气压为30Pa条件下YBCO薄膜的临界转变温度提高至88.57K,较未引入氩气时有大幅提高。并尝试制备不同取向YBCO的多层膜结构,通过控制沉积参数得到底层和顶层均为c轴外延取向,中间层为a轴外延取向的YBCO(c)/YBCO(a)/YBCO(c)结构,测试结果表明成功外延出多层膜结构,为后续基于约瑟夫森结的超导电子器件的制备奠定基础。
[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，

本文编号：1540865