Park Yunkyu, Sim Hyeji, Jo Minguk, Kim Gi-Yeop, Yoon Daseob, Han Hyeon, Kim Younghak, Song Kyung, Lee Donghwa, Choi Si-Young, Son Junwoo
Department of Materials Science and Engineering (MSE), Pohang University of Science and Technology (POSTECH), Pohang, 37673, Republic of Korea.
Max Planck Institute of Microstructure Physics, Weinberg 2, Halle (Saale), 06120, Germany.
Nat Commun. 2020 Mar 16;11(1):1401. doi: 10.1038/s41467-020-15142-x.
Heterogeneous interfaces exhibit the unique phenomena by the redistribution of charged species to equilibrate the chemical potentials. Despite recent studies on the electronic charge accumulation across chemically inert interfaces, the systematic research to investigate massive reconfiguration of charged ions has been limited in heterostructures with chemically reacting interfaces so far. Here, we demonstrate that a chemical potential mismatch controls oxygen ionic transport across TiO/VO interfaces, and that this directional transport unprecedentedly stabilizes high-quality rutile TiO epitaxial films at the lowest temperature (≤ 150 °C) ever reported, at which rutile phase is difficult to be crystallized. Comprehensive characterizations reveal that this unconventional low-temperature epitaxy of rutile TiO phase is achieved by lowering the activation barrier by increasing the "effective" oxygen pressure through a facile ionic pathway from VO sacrificial templates. This discovery shows a robust control of defect-induced properties at oxide interfaces by the mismatch of thermodynamic driving force, and also suggests a strategy to overcome a kinetic barrier to phase stabilization at exceptionally low temperature.
异质界面通过带电物种的重新分布展现出独特现象，以平衡化学势。尽管近期有关于化学惰性界面上电荷积累的研究，但迄今为止，在具有化学反应界面的异质结构中，对带电离子大规模重新配置进行系统研究仍很有限。在此，我们证明化学势失配控制着氧离子在TiO/VO界面的传输，并且这种定向传输前所未有地在有史以来报道的最低温度（≤150°C）下稳定了高质量的金红石TiO外延膜，在该温度下金红石相难以结晶。综合表征表明，金红石TiO相这种非常规的低温外延是通过从VO牺牲模板经由便捷的离子途径增加“有效”氧压来降低活化能垒实现的。这一发现表明通过热力学驱动力失配对氧化物界面缺陷诱导性质进行有力控制，也提出了一种在极低温度下克服相稳定动力学障碍的策略。
