Metal–insulator transition of valence-controlled VO2 thin film prepared by RF magnetron sputtering using oxygen radical
Metal–insulator transition of valence-controlled VO2 thin film prepared by RF magnetron sputtering using oxygen radical
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DOI：
10.7567/jjap.55.06gj11
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发表时间：
2016-05
影响因子：
1.5
通讯作者：
T. Suetsugu;Y. Shimazu;T. Tsuchiya;Masaki Kobayashi;M. Minohara;E. Sakai;K. Horiba;H. Kumigashira-H.-Kumig
中科院分区：
文献类型：
--
作者：
T. Suetsugu;Y. Shimazu;T. Tsuchiya;Masaki Kobayashi;M. Minohara;E. Sakai;K. Horiba;H. Kumigashira-H.-Kumig
以氧自由基为反应气体，采用射频磁控溅射法制备了b轴取向的VO2薄膜。VO2薄膜由氧空位形成的混合价V3+/V4+态组成。在沉积过程中，V3+比强烈地依赖于薄膜厚度和自由基枪的氧分压。随着V3+含量的降低，薄膜的b轴晶格常数增大，金属-绝缘体转变温度(MIT)降低，但V3+含量高达42%的VO2薄膜没有金属-绝缘体转变。在低V3+比的VO2薄膜中，V3Da1g和费米能级附近的能级对应于300K绝缘相的带宽和光谱重量都较小。这些结果表明，混合价态V3+/V4+的控制对于b轴取向的VO2薄膜的MIT是重要的。
We have prepared b-axis-oriented VO2 thin films by RF magnetron sputtering using oxygen radicals as the reactive gas. The VO2 thin films consist of a mixed-valence V3+/V4+ state formed by oxygen vacancies. The V3+ ratio strongly depends on the film thickness and the oxygen partial pressure of the radical gun during deposition. The lattice constant of the b-axis increases and the metal–insulator transition (MIT) temperature decreases with decreasing V3+ ratio, although the VO2 thin films with a high V3+ ratio of 42% do not exhibit MIT. The bandwidths and spectral weights of V 3d a1g and bands at around the Fermi level, which correspond to the insulating phase at 300 K, are smaller in the VO2 thin films with a low V3+ ratio. These results indicate that the control of the mixed-valence V3+/V4+ state is important for the MIT of b-axis-oriented VO2 thin films.