Impact of Composition x on the Refractive Index of NixO
Impact of Composition x on the Refractive Index of NixO
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DOI：
10.1002/pssb.201700463
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发表时间：
2018-03
期刊：
影响因子：
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通讯作者：
M. Becker;F. Michel;A. Polity;P. Klar
中科院分区：
文献类型：
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作者：
M. Becker;F. Michel;A. Polity;P. Klar
在氩氧混合气氛中，通过 Ni 金属靶的离子束溅射 (IBS) 在 c 面 (0001) 蓝宝石衬底上生长外延 NixO 薄膜。通过改变 IBS 过程中的 O2:Ar 比例，可以系统地改变薄膜的组成。通过X射线衍射和扫描电子显微镜进行结构表征。所有 NixO 样品均以 (111) 面外取向生长，并且相对于晶体基底具有明确的双重面内取向关系。样品的表面形貌非常相似。通过 X 射线光电子能谱检查了薄膜的化学键合信息，表明组成 x 可以在 x ≈ 0.9 至 1.5 的宽范围内变化。对于这一系列结构非常相似的样品，光学表征表明 NixO 的折射率光谱色散和带隙对成分有很强的依赖性。 NixO 的折射率对成分 x 的依赖性对文献中报道的 NixO 值的广泛影响有很大贡献。
Epitaxial NixO thin films were grown on c‐plane (0001) sapphire substrates by ion beam sputtering (IBS) of a Ni metal target in a mixed argon and oxygen atmosphere. The composition of the film was varied systematically by varying the O2:Ar ratio in the IBS process. Structural characterization was carried out by X‐ray diffraction and scanning electron microscopy. All the NixO samples grew (111)‐oriented out‐of‐plane and with a defined two‐fold in‐plane orientation relationship relative to the crystalline substrate. The surface morphologies of the samples were very similar. The chemical bonding information of the films was examined by X‐ray photoelectron spectroscopy showing that the composition x could be varied in a wide range of x ≈ 0.9 to 1.5. Optical characterization yielded a strong dependence of the spectral dispersion of the refractive index and the band gap of NixO on composition for this otherwise structurally very similar series of samples. The dependence of the refractive index of NixO on composition x contributes significantly to the wide range of values reported for NixO in literature.