Metallization of Epitaxial VO2 Films by Ionic Liquid Gating through Initially Insulating TiO2 Layers,Nano Letters

当前位置： X-MOL 学术 › Nano Lett. › 论文详情

Our official English website, www.x-mol.net, welcomes your feedback! (Note: you will need to create a separate account there.)

Metallization of Epitaxial VO2 Films by Ionic Liquid Gating through Initially Insulating TiO2 Layers
Nano Letters ( IF 9.6 ) Pub Date : 2016-08-18 00:00:00 , DOI: 10.1021/acs.nanolett.6b01882
Donata Passarello _{1,

2} , Simone G. Altendorf ₂ , Jaewoo Jeong ₁ , Mahesh G. Samant ₁ , Stuart S. P. Parkin _{1,

2}

Affiliation

Ionic liquid gating has been shown to metallize initially insulating layers formed from several different oxide materials. Of these vanadium dioxide (VO₂) is of especial interest because it itself is metallic at temperatures above its metal–insulator transition. Recent studies have shown that the mechanism of ionic liquid gated induced metallization is entirely distinct from that of the thermally driven metal–insulator transition and is derived from oxygen migration through volume channels along the (001) direction of the rutile structure of VO₂. Here we show that it is possible to metallize the entire volume of 10 nm thick layers of VO₂ buried under layers of rutile titanium dioxide (TiO₂) up to 10 nm thick. Key to this process is the alignment of volume channels in the respective oxide layers, which have the same rutile structure with clamped in-plane lattice constants. The metallization of the VO₂ layers is accompanied by large structural expansions of up to ∼6.5% in the out-of-plane direction, but the structure of the TiO₂ layer is hardly affected by gating. The TiO₂ layers become weakly conducting during the gating process, but in contrast to the VO₂ layers, the conductivity disappears on exposure to air. Indeed, even after air exposure, X-ray photoelectron spectroscopy studies show that the VO₂ films have a reduced oxygen content after metallization. Ionic liquid gating of the VO₂ films through initially insulating TiO₂ layers is not consistent with conventional models that have assumed the gate induced carriers are of electrostatic origin.

中文翻译：

通过离子液体门控通过初始绝缘的TiO ₂层对外延VO ₂膜进行金属化

离子液体浇口已经显示出可以金属化最初由几种不同氧化物材料形成的绝缘层。其中二氧化钒（VO ₂）特别受关注，因为它本身在高于其金属-绝缘体转变温度时是金属。最近的研究表明，离子液体门控诱导金属化的机理与热驱动金属-绝缘体跃迁的机理完全不同，并且是由于氧沿VO ₂的金红石结构沿（001）方向通过体积通道迁移而产生的。在这里，我们表明，有可能金属化的VO的10nm厚的层的整个体积₂下金红石型二氧化钛的层埋入（的TiO ₂），厚度可达10 nm。该过程的关键是各个氧化物层中的体积通道的对齐，这些氧化物层具有相同的金红石结构，并具有固定的面内晶格常数。VO ₂层的金属化伴随着在面外方向上高达〜6.5％的大结构膨胀，但是TiO ₂层的结构几乎不受浇铸的影响。TiO ₂层在门控过程中导电性较弱，但与VO ₂层相反，导电性在暴露于空气中时消失。实际上，即使在暴露于空气之后，X射线光电子能谱研究也表明，VO ₂膜在金属化后具有降低的氧含量。VO的离子液体门控_2层膜通过最初绝缘的TiO ₂层是不与已经假定栅极诱导的载体是静电来源的常规型号一致的。

更新日期：2016-08-18

点击分享查看原文

点击收藏

阅读更多本刊新发论文本刊介绍/投稿指南