Thickness Dependence of Structural and Superconducting Properties of Single-Crystal-Like GdBCO Films Prepared by Photo-Assisted MOCVD
Thickness Dependence of Structural and Superconducting Properties of Single-Crystal-Like GdBCO Films Prepared by Photo-Assisted MOCVD
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光辅助MOCVD制备的类单晶GdBCO薄膜的结构和超导性能的厚度依赖性
DOI：
10.1109/tasc.2012.2237514
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发表时间：
2013-04-01
影响因子：
1.8
通讯作者：
Chou, Penchu
中科院分区：
文献类型：
--
作者：
Li, Wei;Li, Shanwen;Chou, Penchu
采用光辅助金属有机化学气相沉积技术在(100)取向的LaAlO3基底上沉积了厚度为0.14-1.62μm的高质量GdBa2Cu3O7-δ(GdBCO)薄膜。研究了生长薄膜中薄膜微观结构和应变弛豫现象的评估及其对 GdBCO 薄膜晶体学和超导性能的影响。观察到类似单晶的横截面形貌，表面致密且无裂纹，并且没有可见的晶界。使用不同厚度生长的 GdBCO 薄膜的 c 轴晶格参数来确定面外应变。结果表明，随着膜厚的增加，应变逐渐缓解。已获得高度双轴织构的 GdBCO 薄膜。对于 0.31μm GdBCO 薄膜样品，面外和面内取向的半峰全宽分别为 0.08 度和 0.47 度。如此低的值与单晶 GdBCO 的值相似。最高临界电流密度 (J(c)) 值类似于 2.5 MA/cm(2)（77 K 和 0 T）。随着薄膜变厚，它们的 J(c) 值逐渐减小。这主要是由于较厚的薄膜中缺乏钉扎中心。
High-quality GdBa2Cu3O7-delta (GdBCO) films with thicknesses of 0.14-1.62 mu m were deposited on (100)-oriented LaAlO3 substrates by photo-assisted metal-organic chemical vapor deposition technique. Evaluation of film microstructure and strain-relaxation phenomenon in the growing films and their effects on the crystallographic and superconducting properties of the GdBCO films have been investigated. A single-crystal-like cross-sectional morphology with dense and crack-free surface and no grain boundary visible was observed. The c-axis lattice parameters of the GdBCO films grown with different thicknesses were used to determine the out-of-plane strain. The result shows that the strain could be gradually relieved as film thickness increases. Highly biaxially textured GdBCO films have been obtained. For a 0.31-mu m GdBCO film sample, the full-widths at half-maximum were 0.08 degrees and 0.47 degrees for out-of-plane and in-plane orientations, respectively. Such low values were similar to that of single-crystal GdBCO. The highest critical current density (J(c)) value is similar to 2.5 MA/cm(2) (77 K and 0 T). As films were getting thicker, their J(c) values decrease gradually. This is mainly attributed to a lack of pinning centers in the thicker films.