材料科学
薄膜
钙钛矿(结构)
结晶度
氧气
四方晶系
外延
化学物理
二次离子质谱法
结晶学
纳米技术
离子
晶体结构
复合材料
量子力学
物理
有机化学
化学
图层(电子)
作者
Kelvin H. L. Zhang,Guoqiang Li,Steven R. Spurgeon,Le Wang,Pengfei Yan,Zhaoying Wang,Meng Gu,Tamás Varga,Mark E. Bowden,Zihua Zhu,Chongmin Wang,Yingge Du
标识
DOI:10.1021/acsami.8b03278
摘要
Changes in the structure and composition resulting from oxygen deficiency can strongly impact the physical and chemical properties of transition-metal oxides, which may lead to new functionalities for novel electronic devices. Oxygen vacancies (VO) can be readily formed to accommodate the lattice mismatch during epitaxial thin film growth. In this paper, the effects of substrate strain and oxidizing power on the creation and distribution of VO in WO3−δ thin films are investigated in detail. An 18O2 isotope-labeled time-of-flight secondary-ion mass spectrometry study reveals that WO3−δ films grown on SrTiO3 substrates display a significantly larger oxygen vacancy gradient along the growth direction compared to those grown on LaAlO3 substrates. This result is corroborated by scanning transmission electron microscopy imaging, which reveals a large number of defects close to the interface to accommodate interfacial tensile strain, leading to the ordering of VO and the formation of semi-aligned Magnéli phases. The strain is gradually released and a tetragonal phase with much better crystallinity is observed at the film/vacuum interface. The changes in the structure resulting from oxygen defect creation are shown to have a direct impact on the electronic and optical properties of the films.
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