THz Transmittance and Electrical Properties Tuning across IMT in Vanadium Dioxide Films by Al Doping
THz Transmittance and Electrical Properties Tuning across IMT in Vanadium Dioxide Films by Al Doping
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通过 Al 掺杂调节二氧化钒薄膜中 IMT 的太赫兹透射率和电性能
DOI：
10.1021/acsami.5b12417
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发表时间：
2016
影响因子：
9.5
通讯作者：
Jiang Yadong
中科院分区：
文献类型：
--
作者：
Wu Xuefei;Wu Zhiming;Ji Chunhui;Zhang Huafu;Su Yuanjie;Huang Zehua;Gou Jun;Wei Xiongbang;Wang Jun;Jiang Yadong
VO 2薄膜由于其绝缘体-金属过渡（IMT）特性覆盖了整个太赫兹（THz）波段，因此被广泛研究，作为调制、开关和存储器件的理想候选材料。但是，由于红外激活声子模引起的一些显著的吸收峰抑制了薄膜的调制能力，限制了薄膜在高THz频率下的应用。本文在（111）方向硅衬底上制备了Al掺杂VO 2薄膜，该薄膜能迅速抵消吸收峰，并表现出广泛的调制特性。Al掺杂使薄膜的拉曼光谱向高频方向移动。这是由于改性VO 2晶体使V <$O键的应变更大，缩短了V <$V二聚体的距离。所有的拉曼结果表明，氧化效果的Al掺杂。XPS分析结果表明，由于Al和V原子的价态不同，钒元素的价态发生了还原。除了表面形貌表征外，还从电学和太赫兹光学两个方面系统地分析了磁滞宽度收缩和电阻变化的IMT特性。另一个不同之处是光学跃迁的温度低于观察到的电学跃迁，这是由跃迁传播机制和边界势垒引起的。
Due to the insulator–metal transition (IMT) performance covering the full terahertz (THz) band, VO2films were extensively investigated as an excellent candidate for modulating, switching, and memory devices. However, some remarkable absorption peaks owing to the infrared-active phonon modes suppressed the films’ modulation ability and restricted the films’ application in high THz frequency. Here we prepared Al-doped VO2films on (111) directional silicon substrate, which rapidly counteracted the absorption peak and exhibited widely modulating properties. Al dopants introduced into the films brought a significant shift to high frequency in Raman spectra. The result was attributed to the effect of modifying VO2crystal, leading the VO bond to be strained more intensively, contracting the distance of the VV dimers. All the Raman results indicated an oxidation effect by Al doping. However, the XPS results showed a valence reduction of the vanadium element, which was caused by the valence difference between V and Al atoms. In addition to the surface morphology characterization, the IMT properties of the shrinkage of hysteresis width and resistance variations in both electrical and THz optical aspects have been systemically analyzed. An additional difference is that the temperature of the optical transition behaves lower than the electrical transition observed, which resulted from the mechanism of transition propagation and boundary barriers.