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Spectroscopic ellipsometry and morphological studies of nanocrystalline NiO and NiO/ITO thin films deposited by e-beams technique
Optical Materials ( IF 3.8 ) Pub Date : 2020-12-26 , DOI: 10.1016/j.optmat.2020.110763
M. Emam-Ismail , M. El-Hagary , H.M. El-Sherif , A.M. El-Naggar , M.M. El-Nahass

The current article reported a new data on the structural, surface morphology and optical properties of multi-thickness nanocrystalline NiO/glass substrate and NiO/ITO/glass substrate semiconductor thin films prepared by electron beam deposition technique. Structural investigation shows that the as-deposited multi-thickness NiO films deposited on a glass substrate crystallize in the form of cubic NaCl type structure. However, ITO thin film has a cubic type structure. Besides, the increase in the crystallite size was observed with increasing the thickness of NiO film, this behavior was confirmed by AFM micrographs. In the spectral range 280 nm–1800 nm, the optical properties of the NiO/glass substrate and NiO/ITO/glass substrate thin films have been investigated using spectroscopic ellipsometry (SE) technique. For NiO/glass substrate sample, the SE results providing direct energy Egdir≈ 3.954 eV, indirect energy Egindir≈ 2.855eV and phonon energy of order 200 meV. In addition, the analysis of the refractive index dispersion gives the atomic number density to be Nfij=2.213x1022cm3. On the other hand, for the NiO (410 nm)/ITO (99 nm)/glass substrate thin film sample, a reduction in the direct transition energy to Egdir≈ 3.24eV and also in the factor Nfij to 1.6x1022cm3was observed. Additionally, the values of the oscillator parameters were calculated for NiO/glass substrate and NiO/ITO/glass substrate thin films using the Wemple-DiDomenico single oscillator model (WDD). Finally, it was found that the values of Urbach energy for NiO/glass substrate and NiO (410 nm)/ITO (99 nm)/glass substrate are very small relative to the energy gap values which indicates that the region of localized sates is very narrow compared to the width of the energy gap.



中文翻译:

电子束技术沉积的纳米晶NiO和NiO / ITO薄膜的光谱椭圆偏振和形态学研究

当前文章报道了有关通过电子束沉积技术制备的多厚度纳米晶态NiO /玻璃衬底和NiO / ITO /玻璃衬底半导体薄膜的结构,表面形态和光学性质的新数据。结构研究表明,沉积在玻璃基板上的沉积后的多厚度NiO薄膜以立方NaCl型结构形式结晶。但是,ITO薄膜具有立方型结构。此外,随着NiO膜厚度的增加,观察到微晶尺寸的增加,这种行为已通过AFM显微照片得到证实。在280 nm–1800 nm的光谱范围内,已经使用分光椭圆偏振光谱(SE)技术研究了NiO /玻璃基板和NiO / ITO /玻璃基板薄膜的光学特性。对于NiO /玻璃基板样品,ËGd一世[R≈3.954 eV,间接能量 ËG一世ñd一世[R≈2.855eV,声子能量为200 meV。另外,通过对折射率色散进行分析,得出原子序数密度为ñF一世Ĵ=2.213X1022C-3。另一方面,对于NiO(410 nm)/ ITO(99 nm)/玻璃基板薄膜样品,直接跃迁能降低到ËGd一世[R≈3.24eV,也是该因子 ñF一世Ĵ1.6X1022C-3被观测到。此外,使用Wemple-DiDomenico单振荡器模型(WDD)计算NiO /玻璃基板和NiO / ITO /玻璃基板薄膜的振荡器参数值。最后,发现相对于能隙值,NiO /玻璃基板和NiO(410 nm)/ ITO(99 nm)/玻璃基板的Urbach能量值非常小,这表明局部态的区域非常小。与能隙宽度相比要窄。

更新日期:2020-12-27
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