Defects and transport in complex oxide thin films
Defects and transport in complex oxide thin films
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DOI：
10.1063/1.2921972
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发表时间：
2008-05-15
影响因子：
3.2
通讯作者：
Lippmaa, Mikk
中科院分区：
文献类型：
--
作者：
Ohnishi, Tsuyoshi;Shibuya, Keisuke;Lippmaa, Mikk
外延氧化物薄膜是新的“氧化物电子”应用的核心，例如激子紫外发光二极管和电阻开关存储器。复合氧化物薄膜通常通过脉冲激光沉积（PLD）来生长，因为该技术被认为是材料不可知的。在这里，我们表明，用于证明使用PLD的基本前提之一，即材料从烧蚀目标转移到膜没有化学计量偏差，是不正确的，即使没有挥发性元素参与。甚至更重要的是，将激光能量密度增加到材料特定阈值以上以获得化学计量膜的常用解决方案不能用于低载流子密度系统（例如SrTiO（3））的情况，其中即使是微小的10（18）cm（-3）阶阳离子非化学计量也会对输运产生显著影响。晶格参数偏差的氧化物薄膜，这往往是不正确地归因于氧的损失，与阳离子非化学计量关系非常好。我们发现，适当的同时选择的烧蚀激光能量密度和烧蚀面积是必不可少的，往往比生长温度和氧气压力获得块状的氧化物异质结构的属性更重要。(C)2008年美国物理研究所。
Epitaxial oxide thin films are at the heart of new "oxide electronic" applications, such as excitonic ultraviolet light-emitting diodes and resistive switching memories. Complex oxide films are often grown by pulsed laser deposition (PLD) because the technique is believed to be material agnostic. Here, we show that one of the fundamental premises used to justify the use of PLD, that material is transferred from an ablation target to the film without stoichiometry deviations, is incorrect even when no volatile elements are involved. Even more importantly, the commonly used solution of increasing the laser energy density above a material-specific threshold value to obtain stoichiometric films cannot be used in the case of low carrier density systems such as SrTiO(3), where even minute 10(18) cm(-3) order cation nonstoichiometry can have a dramatic effect on transport. Lattice parameter deviations in oxide films, which are often incorrectly ascribed to oxygen loss, correlate very well with cation nonstoichiometry. We show that proper simultaneous choice of ablation laser fluence and ablation area is essential and often more important than the growth temperature and oxygen pressure for obtaining bulklike properties in oxide heterostructures. (C) 2008 American Institute of Physics.