LaTiO3外延薄膜的显微结构与电学性能研究

LaTiO₃外延薄膜的显微结构与电学性能研究

乔贝贝, 姚婷婷，江亦潇，陈春林^*，马秀良，叶恒强

(1.中国科学院金属研究所沈阳材料科学国家研究中心,辽宁沈阳110016; 2.中国科学技术大学材料科学与工程学院，辽宁沈阳110016; 3.季华实验室，广东佛山528200)

摘  要 本文利用脉冲激光沉积技术在LaAlO₃(100)和SrTiO₃(100)衬底上生长了LaTiO₃薄膜，利用高分辨X射线衍射和透射电子显微术对薄膜的显微结构进行了系统表征，利用霍尔效应测量系统对薄膜的电学性能进行了研究。XRD结果表明在两种衬底上生长的LaTiO₃薄膜均为单晶薄膜，SrTiO₃衬底上的薄膜具有更高的结晶度。透射电镜显微结构表征的结果显示，LaTiO₃薄膜在两种衬底上均实现了外延生长，SrTiO₃衬底上的薄膜具有更少的晶格缺陷，薄膜与衬底之间的界面也更平直和明锐。薄膜I-V曲线测量的结果表明SrTiO₃衬底上的LaTiO₃薄膜具有更低的电阻率。两种薄膜显微结构和电学性能的优劣主要源自于薄膜与衬底之间的晶格失配大小，更小的界面失配有利于高质量薄膜的外延生长。

关键词   LaTiO₃；脉冲激光沉积；显微结构；透射电子显微学；电阻率

中图分类号：O76；O78；N34；TG115.2 

文献标识码：A   doi:10.3969/j.issn.1000-6281.2022.04.007

Microstructure and electrical properties of LaTiO₃ epitaxial thin films

QIAO Bei-bei^1，2, YAO Ting-ting^1，3, JIANG Yi-xiao^1，3, CHEN Chun-lin^1，3*, MA Xiu-liang¹, YE Heng-qiang³

(1.Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang Liaoning 110016; 2.School of Materials Science and Engineering，University of Science and Technology of China，Shenyang Liaoning 110016; 3.Ji Hua Laboratory, Foshan Guangdong 528200, China)

Abstract   Single-crystal LaTiO₃ thin films were grown on SrTiO₃(100) and LaAlO₃(100) substrates by using pulsed laser deposition (PLD). The microstructures of the thin films were systematically characterized by high-resolution X-ray diffraction and transmission electron microscopy. The electrical properties of the thin films were investigated using a Hall effect measurement system. XRD results indicate that the LaTiO₃ thin films grown on the two substrates are single-crystal films. The thin films on SrTiO₃ substrates have a higher crystallinity. TEM microstructure characterizations reveal that epitaxial growth is achieved on both LaAlO₃(100) and SrTiO₃(100) substrates, and the thin films grown on SrTiO₃(100) substrates have less lattice defects and more flat and sharp film-substrate interfaces. Measurements of I-V curves reveal that the LaTiO₃ thin films on SrTiO₃(100) substrates have a lower electrical resistivity. The different microstructures and electrical properties of the two kinds of thin films mainly originate from their different lattice misfit between films and substrates. A smaller interfacial misfit is beneficial to the epitaxial growth of high-quality thin films.

Keywords   LaTiO₃; pulsed laser deposition; microstructure; transmission electron microscopy; Hall-effect

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