Effects of donor concentration on the electrical properties of Nb-doped BaTiO3 thin films
Effects of donor concentration on the electrical properties of Nb-doped BaTiO3 thin films
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DOI：
10.1063/1.1858056
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发表时间：
2005-02
影响因子：
3.2
通讯作者：
Lifeng Liu;Haizhong Guo;Hui‐bin Lu;S. Dai;B. Cheng;Zheng-hao Chen
中科院分区：
文献类型：
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作者：
Lifeng Liu;Haizhong Guo;Hui‐bin Lu;S. Dai;B. Cheng;Zheng-hao Chen
采用激光分子束外延的方法在MgO衬底上外延生长出BaNbxTi1−xO3（0<x≤0.5）薄膜。x射线衍射和电阻率测量表明，随着铌浓度的增加，薄膜经历了四方到立方和半导体到金属的转变。室温电阻率随铌浓度的增加而单调降低，范围在101 ~ 10−4Ωcm之间。利用小型极化子模型可以很好地拟合薄膜电阻率的温度依赖性，揭示了薄膜中载流子的极化子性质。基于同步辐射的紫外光电子能谱进一步证实了BaTiO3带隙内局域态的存在。
Thin films of BaNbxTi1−xO3(0<x⩽0.5) were epitaxially grown on MgO substrates by laser molecular beam epitaxy. The thin films undergo tetragonal to cubic and semiconductor to metal transitions with Nb concentrations as shown by x-ray diffraction and electrical resistivity measurements. Room temperature resistivities are found to decrease monotonically with increasing Nb concentration and range from 101 to 10−4Ωcm. The fact that the temperature dependence of resistivity of the thin films can be fitted well using a small polaron model reveals the polaronic nature of the charge carriers in the thin films. This conclusion is further confirmed by the existence of localized states within the band gap of BaTiO3 as revealed by synchrotron radiation-based ultraviolet photoelectron spectroscopy.