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利用电化学阳极腐蚀的方法制备了多孔硅膜,实验发现多孔硅膜为多层结构,表面层为纳米结构,其余为微米结构,多孔硅的物理及化学结构的研究表明多孔硅是一种表面上含硅、氧、氢、氟元素组成的化合物包覆着的纳米晶硅粒和微米硅丝.多孔硅的发光主要来自表面纳米结构层,亚微米结构层并未见发光,从实验上证实了多孔硅的发光与量子尺寸效应紧密关联. 相似文献
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研究了掺钛水热法制备多孔硅的Raman光谱和光致发光谱.实验发现,当激光功率较低时,多孔硅的Raman光谱在略低于520cm-1附近表现为一锐的单峰,和晶体硅的Raman光谱类似.随激光功率增大,该单峰向低波数移动,Raman和光致发光峰的强度与激光强度的一次方成正比.当激光功率增大到一定值时,该单峰分裂成两个Raman峰,光致发光谱的强度突然增大,与激光强度之间不再满足一次方的关系,位于低波数一侧的Raman峰随激光功率增大进一步向低波数移动.多孔硅Raman光谱随激光功率的变化是
关键词:
多孔硅
Raman光谱
光致发光 相似文献
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多孔硅表面Ag层对吸附其上的若丹明B染料分子表面增强Raman散射的影响 总被引:1,自引:1,他引:0
采用溶液电镀方法在多孔硅表面制备纳米尺寸的银颗粒,测量了不同镀银多孔硅表面吸附的RhB染料分子以及固态的RhB染料的Raman散射谱。在相同的激发强度下,固态RhB染料的Raman散射最弱,而镀银的多孔硅表面具有明显的增强效果(~10^4)。 相似文献
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采用电化学腐蚀的方法制备多孔硅。对不同实验条件下所得到的多孔硅的拉曼光谱进行了分析,确认多孔硅是具有纳米晶结构特征的材料,肯定了量子限制效应在多孔硅光致发光中的作用。 相似文献
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采用电化学腐蚀制备多孔硅,利用场致发射扫描式电子显微镜(field emission scanning electron microscope,FESEM)观测多孔硅的二维微观形貌,利用Nano Indenter XP中的纳米轮廓扫描仪组件(nano profilometry, NP)得到其三维拓扑分析图像,分析了微观结构差异的原因并讨论了多孔硅内部微观结构对其机械性能的影响;利用MTS Nano Indenter XP纳米压入测量仪器,研究了多孔硅的显微硬度和杨氏模量随压入深度的变化规律,比较了不同孔隙率多孔硅的机械性能差别.实验结果测得40mA/cm2,60mA/cm2,80mA/cm2和100mA/cm2四个不同腐蚀电流密度条件下制备多孔硅样品的孔隙率在60%—80%范围内,孔隙率随着腐蚀电流密度的增加而增大;在氢氟酸(HF)浓度为20%的条件下制备出多孔硅样品的厚度在40μm—50μm范围内;测得多孔硅的平均硬度、平均杨氏模量分别在0.478GPa—1.171GPa和10.912GPa—17.15GPa范围内,并且其数值随腐蚀电流密度的增加而减小,在纳米硬度范围内随压入深度的增加而减小,在显微硬度范围内其数值保持相对恒定,分析了样品表面、厚度、微观结构,及环境对其机械性能的影响,得到了多孔硅力学性能随其微观尺度形貌的变化规律.
关键词:
多孔硅
微观结构
硬度
杨氏模量 相似文献
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多孔硅/多孔氧化铝与PVK复合光致发光特性 总被引:2,自引:1,他引:1
用旋涂法实现了多孔硅、多孔氧化铝与聚乙烯咔唑(PVK)的复合,研究了多孔硅/PVK、多孔氧化铝/PVK复合体系的光致发光性能。PL谱的测试发现,多孔硅/PVK复合体系的PL谱同时具有多孔硅和PVK的发射峰。此外,在485nm的位置出现了一个新峰,讨论了这个峰的来源。而多孔氧化铝与PVK复合后,没有产生新的峰。但多孔氧化铝与PVK复合后,由于多孔氧化铝纳米孔的纳米限制效应使PVK的发光峰出现大幅度蓝移。从多孔硅与多孔氧化铝发光机制的不同出发,讨论了多孔硅、多孔氧化铝与PVK复合后产生不同结果的原因。 相似文献
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量子点或纳米材料发光现象—界面极化子和多孔硅发光 总被引:1,自引:0,他引:1
量子点中的极化子效应是当前量子点研究中的重要问题,其特征急需了解,文章在综述了量子点中限域极化子的概念、可能性和能量随尺寸的变化规律之后,提出了界面限域极化子模型,该模型首次指明本征声子和外来声子都地界面限域分子化的形成有贡献,作者利用此模型分析了多孔硅体系中的光谱特征,证实了表面覆有氧化层的纳米硅的行为十分符合量子限域极化子的特征,这一极化子模型与单个纳米硅结构的发光谱十分一致,此结果对最终揭示多孔硅发光机理有重要意义。 相似文献
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Using a pulsed microplasma source, clusters were produced through the ablation
of a Si cathode and successive supersonic expansion.
The Si cluster beam was deposited onto different substrates and the partial oxidation of the cluster
surface avoided the growth of large agglomerates, preserving their nanocrystalline morphology.
Micro-Raman spectroscopy was used for an accurate size diagnosis of the deposited nanoparticles. The size of the Si dots ranges between 2 and about 15 nm. The Si dots appear to have a Si oxide shell, as confirmed also by structural and compositional analysis through transmission electron microscopy and atomic force microscopy. Double Raman peaks were attributed to small Si agglomerates having a thin substoichiometric Si-O interface. 相似文献
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研究了自组织生长SiGe岛(量子点)中Si组分对形状演化的影响.采用UHV/CVD方法生长了 不同Si组分的SiGe岛,用AFM对其形状和尺寸分布进行了分析,实验结果表明SiGe岛从金字 塔形向圆顶形转变的临界体积随Si组分的增大而增大.通过对量子点能量的应变能项进行修正,解释了量子点中Si组分对形状演化的影响.在特定的工艺条件下得到了单模尺寸分布的 金字塔和圆顶形量子点.结果表明,通过调节SiGe岛中的Si组分,可以实现对SiGe岛形状和 尺寸的控制.
关键词:
自组织生长SiGe岛
Si组分
临界体积 相似文献
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利用准分子脉冲激光晶化非晶硅薄膜是制备高密度尺寸可控的硅基纳米结构的有效方法之一.本文将脉冲激光对非晶硅超薄膜的影响处理为热传导问题,采用了基于Tersoff势函数的分子动力学方法模拟了在非晶氮化硅衬底上2.7 nm超薄非晶硅膜的脉冲激光晶化过程.研究了不同激光能量对非晶硅薄膜晶化形成纳米硅的影响,发现在合适的激光能量窗口下,可以获得高密度尺寸可控的纳米硅薄膜,进而模拟了在此能量作用下非晶硅膜中成核与生长的机理与微观过程,并对晶化所获得的纳米硅薄膜的微结构进行了分析.
关键词:
非晶硅
分子动力学
脉冲激光晶化 相似文献
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Photoluminescence from Si implanted silica is studied as a function of Si fluence and Si concentration profile in order to assess the effect of particle size and size distribution on emission spectra. Peaked (skewed Gaussian) concentration profiles were produced by implanting with 400 keV Si ions and uniform Si profiles were produced by a multi-energy implant sequences. Both as-implanted and annealed samples are shown to exhibit a distinct maximum in the emission intensity as a function of ion fluence, with the intensity increasing with fluence up to the maximum and then decreasing at higher fluences. Samples with a uniform Si profile are also shown to produce emission which is significantly red-shifted relative to that of samples with a peaked Si profile. This is consistent with the fact that such samples are expected to have a narrower particle size distribution (i.e. a greater fraction of larger particles). 相似文献
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提出一种控制脉冲激光烧蚀制备纳米Si晶粒尺寸分布的新方法。在10Pa的Ar环境中,采用脉冲激光烧蚀高阻抗单晶硅靶沉积制备了纳米Si晶薄膜。在羽辉正上方2.0cm,距靶0.3~3.0cm范围内的不同位置引入氩气流,在烧蚀点正下方2.0cm处水平放置单晶Si(111)衬底来收集制备的纳米Si晶粒。利用扫描电子显微镜观察样品表面形貌,并对衬底不同位置上纳米Si晶粒进行统计。结果表明:在不引入气流时,晶粒的尺寸随靶衬间距的增加先增大后减小,晶粒尺寸峰值出现在距靶1.7cm处;引入气流后,晶粒尺寸分布发生变化,在距靶1.7cm引入气流时晶粒尺寸峰值最大,在距靶3.0cm引入气流时晶粒尺寸峰值最小,且出现晶粒尺寸峰值的位置随着引入气流位置的增加而增大。 相似文献
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Cryomilled eutectic aluminum–12% silicon powder was sintered using spark plasma sintering (SPS) to create bulk compacts. The cryomilling serves to break up and disperse the eutectic phase in the powder to create a well-distributed Si phase throughout the matrix and to modify the morphology of the Si phase from plate-like to spherical, whilst refining the aluminium grain size to the nanometric level. The effects of different sintering times and temperatures using SPS on the densification of the powder, the aluminium grain size evolution, the growth of the Si phase and the morphology change of the Si phase were investigated. The compacts were analysed using X-ray diffraction, scanning electron microscopy and optical microscopy. The initial stages of densification appear to be highly dependent on the yield strength of the powder. An estimate of the temperature gradient seen in the powder bed was made and calculated to be near 200?°C at the highest point. The Al and Si phase growth was investigated and it was observed that the Si coarsening rate is increased due to the increased volume of grain boundaries. As the Si coarsens, any pinning effect on the Al grains is lost, resulting in a highly unstable microstructure that coarsens rapidly. 相似文献
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Optimum Quantum Yield of the Light Emission from 2 to 10 nm Hydrosilylated Silicon Quantum Dots 下载免费PDF全文
Xiangkai Liu Yuheng Zhang Ting Yu Xvsheng Qiao Xiaodong Pi Deren Yang 《Particle & Particle Systems Characterization》2016,33(1):44-52
Optimizing the light‐emitting efficiency of silicon quantum dots (Si QDs) has been recently intensified by the demand of the practical use of Si QDs in a variety of fields such as optoelectronics, photovoltaics, and bioimaging. It is imperative that an understanding of the optimum light‐emitting efficiency of Si QDs should be obtained to guide the design of the synthesis and processing of Si QDs. Here an investigation is presented on the characteristics of the photoluminescence (PL) from hydrosilylated Si QDs in a rather broad size region (≈2–10 nm), which enables an effective mass approximation model to be developed, which can very well describe the dependence of the PL energy on the QD size for Si QDs in the whole quantum‐confinement regime, and demonstrates that an optimum PL quantum yield (QY) appears at a specific QD size for Si QDs. The optimum PL QY results from the interplay between quantum‐confinement effect and surface effect. The current work has important implications for the surface engineering of Si QDs. To optimize the light‐emission efficiency of Si QDs, the surface of Si QDs must be engineered to minimize the formation of defects such as dangling bonds at the QD surface and build an energy barrier that can effectively prevent carriers in Si QDs from tunneling out. 相似文献