Exact interband transition energies of VO2 films
Exact interband transition energies of VO2 films
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DOI：
10.1016/j.tsf.2017.09.059
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发表时间：
2018-01-01
期刊：
影响因子：
2.1
通讯作者：
Zhang, Zengming
中科院分区：
文献类型：
--
作者：
Wang, Xiangqi;Fan, Lele;Zhang, Zengming
采用椭圆偏振光谱法测量了不同衬底上不同厚度VO 2薄膜的光学常数随温度的变化。利用标准临界点模型拟合得到了VO 2金属-绝缘体跃迁的带间跃迁能。在测量能量范围内，获得了加热和冷却过程中所有临界点的动态图像。通过在能带模型中引入精细轨道结构，将每个临界点归属于相应的能带跃迁。理论预测的4.7eV的临界点是首次在实验上得到的，这是对O2 P到上a1 g跃迁的响应。我们的工作为单斜和金红石相VO 2的复能带结构提供了新的视角。此外，绝缘体到金属的转变温度被修改，通过调节膜的厚度和基板。
The temperature dependent optical constants of VO2 thin films with different thicknesses on variable substrates were measured by spectroscopic ellipsometry. The exact interband transition energies crossover metal-to-insulator transition of VO2 were obtained using a standard critical point model fitting based on the measured optical constants. The dynamic image of all critical points was obtained during the heating and cooling processes within the measured energy region. By introducing the fine orbital structure into the band model, every critical point was assigned to the corresponding band transition. The critical point of 4.7 eV predicted theoretically, which is response to the transition from O2P to upper a1g, was obtained experimentally for the first time. Our work provides a new view for the complex band scheme of the monoclinic and rutile phase VO2. Moreover, the insulator-to-metal transition temperature is modified by regulating both film thickness and substrate.