钙钛矿氧化物薄膜和异质结的外延生长与物性研究  

Atomic scale controlled epitaxial growth and charaterization investigation of perovskite oxide films and heterojunctions

作　　者：杨国桢[1] 

机构地区：[1]中国科学院物理研究所光物理实验室

出　　处：《量子电子学报》2004年第2期181-187,共7页Chinese Journal of Quantum Electronics

基　　金：国家重大基础研究发展规划资助项目(G1998061412)

摘　　要：用激光分子束外延,原子尺度控制的外延生长出多种钙钛矿氧化物薄膜和异质结。原子力显微镜和高分辨透射电镜测量结果表明,薄膜与异质结的表面和界面均达到原子尺度的光滑。制备出在可见光波段透过率大于85％的导电氧化物薄膜;物性研究结果表明,随着含氧量的不同, BaTiO3薄膜具有绝缘体、半导体和导体的不同特性。BaTiO3/SrTiO3超晶格的光学非线性效应比BaTiO3体材增大23倍。首次在La0.9Sr0.1MnO3/srNb0.01Ti0.99O3(LSMO/SNTO)异质结上,观测到全氧化物p—n结电流和电压的磁调制与正磁电阻效应。在255K条件下,当外加磁场分别为5和1000 Oe时, LSMO/SNTO p-n结的磁电阻变化率R/R0达到: .46.7％和83.4％;在外加磁场为3T时,在100 K条件下,在LSMO/SNTO多层p-n异质结上观测515％的正磁电阻变化率。Perovskite oxide thin films and heterojunctions have been fabricated by laser molecular beam epitaxy controlled in atomic scale. Measurements of atomic force microscopy (AFM) and high-resolution transmission electron microscopy (HRTEM) reveal that the surfaces and interfaces of the thin films and heterojunctions are atom-level-smooth. The optically transparent oxide thin films with transmittances higher than 85% in the visible region have been fabricated. The electrical and optical properties of BaTiO3-x thin films and BaTiO3/SrTiO3 (BTO/STO) superlattices were examined. The BaTiO3-x thin films have the properties of insulator, semiconductor or conductor with different oxygen content. The coefficient of the second harmonic generation of BTO/STO is 23 times larger than that of bulk BaTiO3 crystal. We observed the current and voltage modulations of La0.9Sr0.1MnO3/SrNb0.01Ti0.99O3 p-n junctions by applied magnetic fields and found that the p-n junctions exhibited the positive colossal magnetoresistance (CMR) behavior for the first time. The CMR ratios (△R/R0, △R = RH - R0) are 46.7%, and 83.4% in 5 Oe, and 1000 Oe at 255 K for LSMO/SNTO p-n junction; and the positive CMR ratio as large as 515% at 100 K at 3 T in LSMO/SNTO multilayer p-n heterostructure are found.

关 键 词：薄膜光学 钙钛矿氧化物 异质结 外延生长 激光分子束外延 原子尺度控制 

分 类 号：O484.1[理学—固体物理] O484.41[理学—物理]