Intense Ultraviolet Photoluminescence Observed at Room Temperature from NiO Nano-porous Thin Films Grown by the Hydrothermal Technique
Intense Ultraviolet Photoluminescence Observed at Room Temperature from NiO Nano-porous Thin Films Grown by the Hydrothermal Technique
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DOI：
10.1557/opl.2012.1699
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发表时间：
2013
期刊：
影响因子：
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通讯作者：
S. Sarangi;Dongyuan Zhang;P. Sahoo;K. Uchida;S. Sahu;S. Nozaki
中科院分区：
文献类型：
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作者：
S. Sarangi;Dongyuan Zhang;P. Sahoo;K. Uchida;S. Sahu;S. Nozaki
摘要采用水热法成功制备了高质量的纳米多孔NiO薄膜，并在室温下观察到了强的紫外发光。SEM图像显示纳米多孔NiO膜的孔径从70到500 nm。XRD、Micro拉曼和FTIR表征结果证实了NiO的立方结构。从吸收光谱估计的光学带隙被发现是3.86和4.51 eV。前者与体相NiO的氧化还原能力相近，后者则远高于体相NiO。增加的带隙归因于NiO纳米晶体中的量子限制，这可能存在于纳米多孔NiO膜中。室温光致发光（PL）谱显示出在3.70 eV处的强发光峰以及在UV和近UV波长区域的其他几个峰。在3.70 eV的强烈的紫外发光与近带边发射和其他与缺陷相关的发射。高质量的纳米多孔NiO壁具有大的表面积与体积比，提供了强烈的紫外发射。
ABSTRACT We have successfully formed high-quality nanoporous NiO films by the hydrothermal technique and observed intense ultraviolet (UV) luminescence at room temperature. The SEM image reveals nanoporous NiO films with pore diameters from 70 to 500 nm. The results of XRD, Micro Raman and FTIR characterizations confirm the cubic structure of NiO. The optical band gaps estimated from the absorption spectrum are found to be 3.86 and 4.51 eV. The former is similar to that of bulk NiO, while the latter is much higher than that of bulk NiO. The increased band gap was attributed to the quantum confinement in the NiO nanocrystals, which may be present in the nanoporous NiO film. The room-temperature photoluminescence (PL) spectrum shows a peak of intense luminescence at 3.70 eV and several other peaks in the UV and near-UVwavelength regions. The intense UV luminescence at 3.70 eV was associated with the near band-edge emission and the others with defect-related emission. The high-quality wall of nanoporous NiO with a large surface-to-volume ratio provided the intense UV emission.