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Photoluminescence and Optically Pumped Ultraviolet Lasing from Nanocrystalline ZnO Thin Films Prepared by Thermal Oxidation of High—Quality ZnS Thin Films 总被引:2,自引:0,他引:2 下载免费PDF全文
We present a simple and useful method for preparing high-quality nanocrystalline ZnO thin films,i.e.the thermal oxidation of high-quality ZnS films prepared by the low-pressure metal-organic chemical vapour deposition technique.The x-ray diffraction measurements reveal that the nanocrystalline ZnO has a hexagonal wurtzite structure.Raman spectra show that the longitudinal optical phonon with the E1-mode appears at 578 cm^-1.The multiple phonon scattering process is also observed,indicating the formation of a high-quality nanocrystalline ZnO thin film.The photoluminescence spectrum has a single emission peak at 3.264eV from the free-exciton mission,under the condition of low excitation power at room temperature.However,when excitation intensities exceed the threshold of 150kW/cm^2,a new and narrow peak emerges at lower energies,which are attributed to exciton-exciton collisions,and is called the P line.The intensity of this peak increases superlinearly with the pumping power over a threshold value.This supplies strong evidence of stimulated emission.The multiple longitudinal cavity modes observed in the stimulated emission spectrum indicate the successful realization of optically pumped lasing from nanocrystalline ZnO films at room temperature. 相似文献
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利用化学气相沉积(CVD)的方法通过热氧化高纯锌粉在硅衬底上得到氧化锌微米花. X射线衍射(XRD)结果表明,其具有六角纤锌矿晶体结构.场发射扫描电子显微镜(FE-SEM)图像表明,合成的样品是由很多长且直的ZnO亚微米棒组成的微米花, 具有六角棱柱端面,棒的长度在30μm到50μm之间.在背向共振拉曼散射光谱测量中,观测到ZnO A1(LO)的五阶声子紫外共振拉曼散射,表明样品具有较高的晶体质量.在变温光致发光谱测量中,观察到明显的中性受主束缚激子(A0X)的
关键词:
ZnO微米花
光致发光
共振拉曼
“负热淬灭”效应 相似文献
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本文研究了用电子束分蒸技术制备的ZnO∶Er薄膜的结构和发光特性.X射线衍射(XRD)谱表明,六角晶体结构的ZnO∶Er薄膜具有强的择优c轴取向(002).在室温下,用阴极射线激发样品,观测到强的蓝光(455nm)发射.本文认为,蓝光发射是ZnO∶Er薄膜中铒离子(Er3+)的激发态4F5/2到基态4I15/2的辐射跃迁.研究薄膜的阴极射线发光强度与电子束流的关系时发现,蓝光发射强度强烈地依赖于电子束流的大小.此外,超过阈值电子束流0.6μA,蓝光发射强度首先迅速增加,然后缓慢地增加,趋于饱和,根据瓶颈效应和稀土发光理论很好地解释了这一实验结果. 相似文献
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通过简单的水热合成路线,在没有模板、表面活性剂的作用和未处理的基底上合成出铝掺杂ZnO 纳米盘,并以纳米盘为基底自组装合成了ZnO纳米棒阵列.扫描电镜(SEM)观察到铝掺杂ZnO纳米盘的厚度为 200 nm,纳米盘的尺寸约为2 μm;纳米棒的直径约为150 nm,长约1.5 μm.通过不同生长阶段的形貌变化探讨了ZnO纳米结构的形成机理,表明自组装过程存在两个成核阶段.另外, 研究了铝离子掺杂对样品光致发光性质的影响. 相似文献
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A new rare earth catalyst system was found in our laboratory. Not only styrene and iso-prene are copolymerized but also styrene and butadiene are copolymerized with the new catalyst system-4f metal compounds-alkyl aluminium compounds-other components. The copolymers are characterized as the block copolymers containing 4.0-4.5(%) gels, 22.0-97.7(%) cis-l,4-contents and 8.3-79.8 (mol%) styrene contents by means of IR, 1H-NMR,13C-NMR and Dynamic mechanic properties. 相似文献
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Block polymer of alternating copolymers, poly[(ST-a-MA)-b(IP-a-MMA)-b-(ST-a-MA)](I), has been synthesized in the presence of AlEt_(1.5)Cl_(1.5),by using Mn_2(CO)_(10)/CBr_4. initiation system.The GPC results indicate that there is no unreacted prepolymer in I purified by precipitation andfractionation. The study of NMR shows that every block of polymer I has alternating structure. The dynamicmechanical properties of I measured by torsional braid method indicate that the polymer has two T_g s,being 38 and 75℃, respectively. The transmission electron micrographs of I show they have two phasestructure and the domain size increases with increasing molecular weight of hard block. 相似文献
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Using a mixture of ZnO and Te powders as the source material, ZnO nanoleaves with high yield and uniform morphology are fabricated by thermal evaporation. Each nanoleaf is constructed with a nanowire and a nanodisc on one side of the nanowire near the top. The polygonal nanodisc is in symmetric distribution in relation to the nanowires and has polar planes ±(0001) as surfaces. A local homoepitaxial growth mechanism of ZnO polar nanodiscs induced by Te is proposed. With thin nanodiscs, the ZnO nanoleaves could be used in nanolasers, sensors, and photoelectronic nanodevices. Room-temperature photoluminescence result implies good crystalline quality of the ZnO nanoleaves. 相似文献