Massively Strained VO2 Thin Film Growth on RuO2
Massively Strained VO2 Thin Film Growth on RuO2
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DOI：
10.1021/acs.cgd.0c00120
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发表时间：
2020-04-01
影响因子：
3.8
通讯作者：
Flege, Jan Ingo
中科院分区：
文献类型：
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作者：
Fischer, Simon;Krisponeit, Jon-Olaf;Flege, Jan Ingo
应变工程二氧化钒薄膜是改变这种材料从半导体到金属的一级转变特征的一种方法。在本研究中，我们通过利用 VO2/RuO2 系统中沿着金红石结构的 c 轴发生的 8.78% 的非常大的晶格失配来扩展可利用的应变范围。我们通过原子氧支持的反应分子束外延 (MBE) 在两个不同表面取向的单域 RuO2 岛上生长了 VO2 薄膜。通过空间分辨光电子和 X 射线吸收光谱检查这些薄膜，确认了正确的化学计量。低能电子衍射揭示了 VO2 薄膜确实在 RuO2(110) 上完全应变生长，表现出先前未报道的 (2 x 2) 重建。在 TiO2(110) 基底上，我们重现了这种重建，并将其归因于高氧化学势引起的富氧终止。相反，在 RuO2(100) 上，薄膜完全松弛。因此，所提出的生长方法允许同时访问从块状结构到大应变区域的显着应变窗口。
Strain engineering vanadium dioxide thin films is one way to alter this material's characteristic first order transition from semiconductor to metal. In this study, we extend the exploitable strain regime by utilizing the very large lattice mismatch of 8.78% occurring in the VO2/RuO2 system along the c axis of the rutile structure. We have grown VO2 thin films on single-domain RuO2 islands of two distinct surface orientations by atomic oxygen-supported reactive molecular beam epitaxy (MBE). These films were examined by spatially resolved photoelectron and X-ray absorption spectroscopy, confirming the correct stoichiometry. Low energy electron diffraction then reveals the VO2 films grow indeed fully strained on RuO2(110), exhibiting a previously unreported (2 x 2) reconstruction. On TiO2(110) substrates, we reproduce this reconstruction and attribute it to an oxygen-rich termination caused by the high oxygen chemical potential. On RuO2(100), on the contrary, the films grow fully relaxed. Hence, the presented growth method allows for simultaneous access to a remarkable strain window ranging from bulk-like structures to massively strained regions.