Controlling Metal–Insulator Transitions in Vanadium Oxide Thin Films by Modifying Oxygen Stoichiometry
Controlling Metal–Insulator Transitions in Vanadium Oxide Thin Films by Modifying Oxygen Stoichiometry
复制标题
通过改变氧化学计量控制氧化钒薄膜中的金属-绝缘体转变
DOI：
10.1021/acsami.0c18327
复制
发表时间：
2021
影响因子：
9.5
通讯作者：
Schuller, Ivan K.
中科院分区：
文献类型：
--
作者：
Lee, Min-Han;Kalcheim, Yoav;Valle, Javier del;Schuller, Ivan K.
钒氧化物是强相关材料，表现出金属-绝缘体转变（MIT）以及严重依赖于氧化学计量的各种结构和磁性。因此，精确控制这些材料中的氧化学计量至关重要，特别是在薄膜中。这项工作展示了一种高真空气体析出技术，该技术允许通过仔细调整热力学条件来改变 VOX 薄膜中的氧气浓度。我们能够控制蓝宝石基板上 VO2、V3O5 和 V2O3 相之间的演化，克服了相邻 Magnéli 相的狭窄相稳定性。人们发现了多种退火路线来实现所需的阶段并最终控制 MIT。转化膜显着的 MIT 以及基于 X 射线衍射测量和 X 射线光电子能谱的详细结构研究表明，获得并稳定了最佳化学计量。使用这种技术，我们发现由于应变和有限尺寸效应，薄膜 V-O 相图与块体材料的相图不同。我们的研究展示了战略性调整复杂氧化物中氧化学计量的新途径，并为了解 VOX 薄膜的相稳定性提供了路线图。
Vanadium oxides are strongly correlated materials which display metal–insulator transitions (MITs) as well as various structural and magnetic properties that depend heavily on oxygen stoichiometry. Therefore, it is crucial to precisely control oxygen stoichiometry in these materials, especially in thin films. This work demonstrates a high-vacuum gas evolution technique which allows for the modification of oxygen concentrations in VOXthin films by carefully tuning the thermodynamic conditions. We were able to control the evolution between VO2, V3O5, and V2O3phases on sapphire substrates, overcoming the narrow phase stability of adjacent Magnéli phases. A variety of annealing routes were found to achieve the desired phases and eventually control the MIT. The pronounced MIT of the transformed films along with the detailed structural investigations based on X-ray diffraction measurements and X-ray photoelectron spectroscopy show that optimal stoichiometry is obtained and stabilized. Using this technique, we find that the thin-film V–O phase diagram differs from that of the bulk material because of strain and finite size effects. Our study demonstrates new pathways to strategically tune the oxygen stoichiometry in complex oxides and provides a road map for understanding the phase stability of VOXthin films.