Mechanisms of electron transport in BaTiO3 ultrathin epitaxial films in the temperature range 40K-295K
Mechanisms of electron transport in BaTiO3 ultrathin epitaxial films in the temperature range 40K-295K
复制标题
DOI：
10.1088/2053-1591/aaf24f
复制
发表时间：
2019-02-01
影响因子：
2.3
通讯作者：
Rybkin, A. G.
中科院分区：
文献类型：
--
作者：
Andreeva, N., V;Petrov, A. A.;Rybkin, A. G.
本文报道了宽温区BaTiO_3外延铁电薄膜中电子输运机制的实验研究结果。为了实现这一目的，我们采用不同的铁电薄膜厚度（3 ~ 12 nm）制备了基于STO/LSMO/BTO/Au结构的铁电隧道结。在40 K到300 K的温度范围内测量了异质结构的铁电和电学性质。根据实验结果，我们发现，在钛酸钡外延薄膜的主要输运机制是由膜厚。低于一定厚度的钛酸钡膜，在通过该结构的电流的主要贡献是由于弹性隧穿。增加铁电膜的厚度导致非弹性隧穿的影响，主要是由于与氧化物亚晶格中的阳离子和阴离子空位引起的陷阱的相互作用。我们认为BaTiO_3薄膜输运机制的特异性是由薄膜厚度与注入电子的平均自由程之比决定的，沿着与铁电矫顽场同步的复极化过程。后一点已被广泛温度范围内的实验研究结果所证实。
In this paper, we report the results of experimental study of electron transport mechanisms in ferroelectric BaTiO3 ultrathin epitaxial films in a broad temperature range. For this purpose ferroelectric tunnel junctions based on STO/LSMO/BTO/Au structures were fabricated with different thicknesses of ferroelectric films (from 3 to 12 nm). Ferroelectric and electrical properties of heterostructures were measured at temperatures ranging from 40 Kto 300 K. Based on experimental results, we find that prevailing transport mechanisms in BaTiO3 epitaxial thin film is determined by the film thickness. Below the certain thickness of the BaTiO3 film, a dominant contribution in the current through the structure is due to elastic tunneling. Increasing the thickness of the ferroelectric film leads to an impact from inelastic tunneling, mainly due to an interaction with traps caused by cation and anion vacancies in oxide sub-lattices. Wesuppose that the specificity of transport mechanisms in BaTiO3 ultrathin films is defined by the ratio of film thickness and the mean free path of injected electrons, along with repolarization processes synchronized with the ferroelectric coercive field. The latter point has been confirmed by the results of experimental study in a broad temperature range.