This paper presents the study of surface morphological, optical and microstructural features of zinc oxide (ZnO) nanofilm layered upon p-type Si substrate of <100> orientation by employing conventional RF magnetron sputtering system at different annealing temperatures. The effect of annealing on the nano-film is examined using different characterization techniques such as Atomic Force Microscopy (AFM), Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD), FTIR (Fourier Transform Infrared Spectroscopy), UV-vis spectroscopy and Raman spectroscopy. The sharp diffraction peak at (002) orientation is seen by the XRD spectra which signifies a better growth of single crystalline thin film along the z-axis with the hexagonal wurtzite crystal structure. The surface morphological study shows that the grain size of the thin film intensifies from 22.06 nm to 36.77 nm when the annealing temperature is increased whereas there is a decrease in the values of lattice constants (a=b, c), FWHM (full width at half maximum), residual stress, lattice strain and dislocation density by increasing annealing temperature. The enhancement in the grain size makes the thin film appropriate for MEMS device applications including piezoelectric energy harvesters, gas sensors, etc. The optical bandgap of the ZnO thin film is estimated using Kubelka-Munk (KM) approach and it decreases from 3.23 to 3.16 eV for As-deposited, 400 °C, 600 °C and 800 °C respectively which makes the annealed thin film apposite for optoelectronic device applications. The intensity of the Raman peaks strengthens with the annealing temperature. These results prove that the annealing extensively enhances the crystallinity, structural, morphological and optical features of ZnO thin film and hence becomes suitable for nanoelectronic device applications.

中文翻译：

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增强热退火氧化锌纳米膜的结构，形态和光学特性

本文介绍了采用常规RF磁控溅射系统在不同退火温度下对<100>取向的p型Si衬底上形成的氧化锌（ZnO）纳米膜的表面形貌，光学和微观结构特征的研究。使用不同的表征技术，例如原子力显微镜（AFM），扫描电子显微镜（SEM），X射线衍射（XRD），傅立叶变换红外光谱（Fourier Transform Infrared Spectroscopy），傅里叶变换红外光谱（UV-vis），检查了退火对纳米膜的影响光谱和拉曼光谱。通过XRD光谱观察到在（002）方向上的尖锐衍射峰，这表明具有六方纤锌矿晶体结构的单晶薄膜沿z轴更好地生长。表面形貌研究表明，当退火温度升高时，薄膜的晶粒尺寸从22.06 nm增大到36.77 nm，而晶格常数（a = b，c），FWHM（在最大值），残余应力，晶格应变和位错密度（通过提高退火温度）。晶粒尺寸的增加使该薄膜适用于包括压电能量收集器，气体传感器等在内的MEMS器件应用。使用Kubelka-Munk（KM）方法估算ZnO薄膜的光学带隙，并将其从3.23降低至3.16 eV分别用于沉积后的400°C，600°C和800°C，这使得退火的薄膜适合用于光电器件。拉曼峰的强度随着退火温度的增加而增强。