Site-Selective Oxygen Vacancy Formation Derived from the Characteristic Crystal Structures of Sn-Nb Complex Oxides
Site-Selective Oxygen Vacancy Formation Derived from the Characteristic Crystal Structures of Sn-Nb Complex Oxides
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Sn-Nb 复合氧化物特征晶体结构衍生的位点选择性氧空位形成
DOI：
10.1021/acs.jpcc.0c11423
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发表时间：
2021
期刊：
影响因子：
--
通讯作者：
Nishio Keishi
中科院分区：
文献类型：
--
作者：
Samizo Akane;Minohara Makoto;Kikuchi Naoto;Bando Kyoko K.;Aiura Yoshihiro;Mibu Ko;Nishio Keishi
二价锡氧化物作为一种新型的p型氧化物半导体材料，是实现未来氧化物电子器件的关键材料，受到人们的广泛关注。最近，p型Sn2Nb2O7和SnNb2O6被开发出来，但实际应用需要通过降低缺陷浓度来提高空穴迁移率。在本工作中，我们研究了降低空穴产生效率和空穴迁移率的氧空位(VO··)的形成与锡-Nb复合氧化物晶体结构之间的关系。扩展X射线吸收精细结构谱和Rietveld X射线衍射数据分析表明，在这两种Nb锡酸盐中，VO··都是在与锡离子键合的O位上优先形成的。此外，p型Sn2Nb2O7中Sn2Nb2O7中锡离子周围的VO··比p型SnNb2O6中的VO··多，说明VO··对空穴产生效率较低有影响。为了解释VO··的形成与晶体结构的关系，我们基于键价和和德拜温度来评估SnO键的强度。两种锡-Nb复合氧化物的键强差异是通过Sn2+的空间位阻和非对称电子密度分布联系在一起的。这表明材料设计的重要性，重点放在锡离子周围的局部结构上，以防止p型Sn2+氧化物中VO··的形成。
Divalent tin oxides have attracted considerable attention as novel p-type oxide semiconductors, which are essential for realizing future oxide electronic devices. Recently, p-type Sn2Nb2O7and SnNb2O6were developed; however, an enhanced hole mobility by reducing defect concentrations is required for practical use. In this work, we investigated the correlation between the formation of oxygen vacancy (VO··), which may reduce the hole-generation efficiency and hole mobility, and the crystal structure in Sn–Nb complex oxides. Extended X-ray absorption fine structure spectroscopy and a Rietveld analysis of X-ray diffraction data revealed the preferential formation of VO··at the O site bonded to the Sn ions in both the tin niobates. Moreover, a larger amount of VO··around the Sn ions was found in the p-type Sn2Nb2O7than in the p-type SnNb2O6, indicating the effect of VO··on the low hole-generation efficiency. To elucidate the dependence of the formation of VO··on the crystal structure, we evaluated the Sn–O bond strength based on the bond valence sum and Debye temperature. The differences in the bond strengths of the two Sn–Nb complex oxides are correlated through the steric hindrance of Sn2+with an asymmetric electron density distribution. This suggests the importance of the material design with a focus on the local structure around the Sn ions to prevent the formation of VO··in p-type Sn2+oxides.