共查询到19条相似文献,搜索用时 296 毫秒
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采用低压化学气相沉积方法,依靠纯SiH4气体的热分解反应,在SiO2表面上自组织生长了Si纳米量子点.实验研究了SiO2膜的薄层化对Si纳米量子点光致发光特性的影响.结果表明,当SiO2膜厚度减薄至6nm以下时,Si纳米量子点中的光生载流子会量子隧穿超薄SiO2层,并逃逸到单晶Si衬底中去,从而减少了光生载流子通过SiO2/Si纳米量子点界面区域内发光中心的辐射复合效率,致使光致发光强度明显减弱.测试温度的变化对Si纳米量子点光致发光特性的影响,则源自于光生载流子通过SiO2/Si纳米量子点界面区域附近非发光中心的非辐射复合所产生的贡献. 相似文献
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SiO2膜的薄层化对自组织生长Si纳米量子点发光特性的影响 总被引:4,自引:0,他引:4
采用低压化学气相沉积方法,依靠纯SiH4气体的热分解反应,在SiO2表面上自组织生长了Si纳米量子点.实验研究了SiO2膜的薄层化对Si纳米量子点光致发光特性的影响.结果表明,当SiO2膜厚度减薄至6nm以下时,Si纳米量子点中的光生载流子会量子隧穿超薄SiO2层,并逃逸到单晶Si衬底中去,从而减少了光生载流子通过SiO2/Si纳米量子点界面区域内发光中心的辐射复合效率,致使光致发光强度明显减弱.测试温度的变化对Si纳米量子点光致发光特性的影响,则源自于光生载流子通过SiO2/Si纳米量子点界面区域附近非发光中心的非辐射复合所产生的贡献. 相似文献
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Si基纳米结构的电子性质 总被引:1,自引:0,他引:1
各种Si基纳米发光材料在Si基光电子器件及其全Si光电子集成技术中具有潜在的应用前景,从理论和实验上对其电子结构进行研究,有助于我们深化对其发光机制的认识与理解。本文主要从量子限制效应发光这一角度,着重介绍了Si纳米晶粒、Ge/Si量子点,SiO2/Si超晶格和超小尺寸Si纳米团簇等不同Si基纳米结构的电子性质以及它们与发光特性之间的关系。还讨论了介质镶嵌和表面钝化对其电子结构的影响。 相似文献
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在量子点表面包覆二氧化硅壳层,能够有效的保护纳米粒子核不受外界环境的影响,使得它在光电子器件和生物标记等领域中有着广泛的应用前景。通过一锅法制备高质量CdS:Mn/ZnS量子点,然后利用反相微乳液方法在量子点的表面继续包覆SiO2层,得到CdS:Mn/ZnS@SiO2多层核壳结构量子点材料。化学性质稳定的ZnS及SiO2材料的包覆使CdS量子点材料的毒副作用降低并有效提高其稳定性,然而CdS:Mn/ZnS量子点的大部分性能在包覆SiO2后都保持不变,因此CdS:Mn/ZnS@SiO2量子点在光学应用中有很大的应用潜力。 相似文献
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采用水相法制备了颗粒尺寸为3.75nm的硒化锌(ZnSe)量子点,采用表面活性剂将ZnSe量子点转移到有机相聚(2-甲氧基-5-辛氧基)对苯乙炔(MO-PPV)中,获得了MO-PPV/ZnSe复合材料。通过对MO-PPV和ZnSe量子点的吸收光谱(ABS)和光致发光(PL)光谱的研究发现,随着ZnSe量子点掺杂浓度的提高,复合材料的发光强度明显增强,发光峰位置出现了蓝移。当ZnSe∶MO-PPV的质量比为1∶0.181时,发光峰位置蓝移10nm。结果表明,MO-PPV与ZnSe量子点之间存在着能量传递,这是导致MO-PPV/ZnSe量子点复合材料具有PL增强的重要原因。 相似文献
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用PL谱测试研究了GaAs和不同In组份InxGa1-xAs(x=0.1,0.2,0.3)覆盖层对分子外延生长的InAs/GaAs自组织量子点发光特性的影响,用InxGa1-xAs外延层覆盖InAs/GaAs量子点,比用GaAs做 其发光峰能量向低有端移动,发光峰半高度变窄,量子点发光峰能量随温度的红移幅度较小,理论计算证实这是由于覆盖层InxGa1-xAs减小了InAs表面应力导致发光峰红移,而In元素有效抑制了InAs/GaAs界面组份的混杂,量子点的均匀性得到改善,PL谱半高宽变窄,用InGaAs覆盖的In0.5Ga0.5As/GaAs自组织量子点实现了1.3μm发光,室温下PL谱半高宽为19.2meV,是目前最好的实验结果。 相似文献
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报道了在无水无氧环境下利用热解反应将硒化锌量子点组装入介孔二氧化硅有序孔道内的方法,采用X射线衍射、透射电子显微成像及能量散射谱等测试方法分析了体系的微观结构,并采用紫外-可见光吸收光谱仪和荧光光谱仪研究了其光学性质.结果表明硒化锌量子点被组装在介孔二氧化硅的孔道内;与硒化锌体材料本征吸收谱相比,组装在介孔内的量子点的吸收光谱表现出显著的蓝移,这归结于量子尺寸效应. 相似文献
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CdS Quantum Dots Encapsulated in Chiral Nematic Mesoporous Silica: New Iridescent and Luminescent Materials 下载免费PDF全文
Thanh‐Dinh Nguyen Wadood Y. Hamad Mark J. MacLachlan 《Advanced functional materials》2014,24(6):777-783
Simultaneous integration of light emission and iridescence into a semiconducting photonic material is attractive for the design of new optical devices. Here, a straightforward, one‐pot approach for liquid crystal self‐assembly of semiconductor quantum dots into cellulose nanocrystal‐templated silica is developed. Through a careful balance of the intermolecular interactions between a lyotropic tetraalkoxysilane/cellulose nanocrystal dispersion and water‐soluble polyacrylic acid/mercaptopropionic acid‐stabilized CdS quantum dots, CdS/silica/nanocellulose composites that retain both chiral nematic order of the cellulose nanocrystals and emission of the quantum dots are successfully co‐assembled. Subsequent removal of the cellulose template and organic stabilizers in the composites by controlled calcination generates new freestanding iridescent, luminescent chiral nematic mesoporous silica‐encapsulated CdS films. The pores of these materials are accessible to analytes and, consequently, the CdS quantum dots undergo strong luminescence quenching when exposed to TNT solutions or vapor. 相似文献
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Shirui Guo Duoduo Bao Srigokul Upadhyayula Wei Wang Ali B. Guvenc Jennifer R. Kyle Hamed Hosseinibay Krassimir N. Bozhilov Valentine I. Vullev Cengiz S. Ozkan Mihrimah Ozkan 《Advanced functional materials》2013,23(41):5199-5211
Interest in graphene as a two‐dimensional quantum‐well material for energy applications and nanoelectronics has increased exponentially in the last few years. The recent advances in large‐area single‐sheet fabrication of pristine graphene have opened unexplored avenues for expanding from nano‐ to meso‐scale applications. The relatively low level of absorptivity and the short lifetimes of excitons of single‐sheet graphene suggest that it needs to be coupled with light sensitizers in order to explore its feasibility for photonic applications, such as solar‐energy conversion. Red‐emitting CdSe quantum dots are employed for photosensitizing single‐sheet graphene with areas of several square centimeters. Pyridine coating of the quantum dots not only enhances their adhesion to the graphene surface, but also provides good electronic coupling between the CdSe and the two‐dimensional carbon allotrope. Illumination of the quantum dots led to injection of n‐carrier in the graphene phase. Time‐resolved spectroscopy reveals three modes of photoinduced electron transfer between the quantum dots and the graphene occurring in the femtosecond and picosecond time‐domains. Transient absorption spectra provide evidence for photoinduced hole‐shift from the CdSe to the pyridine ligands, thereby polarizing the surface of the quantum dots. That is, photoinduced electrical polarization, which favors the simultaneous electron transfer from the CdSe to the graphene phase. These mechanistic insights into the photoinduced interfacial charge transfer have a promising potential to serve as guidelines for the design and development of composites of graphene and inorganic nanomaterials for solar‐energy conversion applications. 相似文献
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硅基量子点的制备及其发光特性 总被引:1,自引:0,他引:1
硅基光电子学无疑是今后光电子学发展的方向,这就要求硅基材料能够满足发光器件的要求,从而达到光电集成的目的。因为硅体具有非直接带隙的特点,共发光效率低,所以利用硅基低维量子结构,尤其是量子点结构提高硅基材料的发光性能一直是国内外本领域的一个研究特点。本文对近年来硅基量子点的制备及发光特性研究所取得的进展和结果进行了总结和评述,并对今后的发展提出了看法。 相似文献
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量子点电致发光器件发光层能级变化与驱动电压的关系研究 总被引:1,自引:0,他引:1
以量子点电致发光器件(QLED)中能级分布和载流子浓度的关系为理论基础,研究了QLED发光层能级变化与驱动电压的关系,建立了数学模型.以CdSe/ZnS核壳结构量子点为发光层,计算了器件正常发光时的阈值电压,分析了电流密度与量子点中电子准费米能级与空穴准费米能级之差的关系.结果表明,当驱动电压大于9.8V时,CdSe/ZnS中电子的准费米能级与空穴的准费米能级之差大于1.03 eV,量子点电致发光器件正常发光;理论模型证实由于电子在发光层与电子传输层界面的大量积聚,导致淬灭发生,降低发光效率. 相似文献
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Wei Yang Tianchi Leng Hao Sun Weicheng Miao Xinyi Wang Dou Xu Can Zhang Yimin Fang 《Advanced functional materials》2023,33(45):2306103
Significant progress has recently been made in the application of oxidized graphene (GO) quantum dots as enzyme mimics in various biomedical fields due to their bio-compatibility and excellent solubility in physiological media. However, their catalytic performance and controllability are barely satisfactory. Here, this study constructs oxygen-functionalized polypyrrole quantum dots (o-ppy QDs) with excellent peroxidase activity in a mild condition. Compared with oxidized graphene QDs, o-ppy QDs exhibit superior catalytic efficiency (120 times higher than HRP). More importantly, it is found that guanine (G) and adenine (A) bases possess higher binding affinities to o-ppy QDs. G base is able to significantly increase the peroxidase activity while A base decreases the activity, providing a fascinating method to precisely regulate the catalytic activity of o-ppy QDs in a programmable manner by the design of DNA sequences. The enhancement on the peroxidase by G base regulation is attributed to the existence of carbonyl group that promotes its catalytic activity, while A base tends to block the original carbonyl group on o-ppy QDs. Based on this feature, a colorimetric and fluorescent dual-mode biosensor for detecting DNA methylation is developed. This study holds significant theoretical and practical implications for the development of nanozymes and precise regulation of their catalytic activity. 相似文献
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S. Chakrabarti S. Fathpour K. Moazzami J. Phillips Y. Lei N. Browning P. Bhattacharya 《Journal of Electronic Materials》2004,33(4):L5-L8
The effect of pulsed laser annealing (PLA), using an excimer laser, on the luminescence efficiency of self-organized InAs/GaAs
and In0.4Ga0.6As/GaAs quantum dots has been investigated. It is found that such annealing can enhance both the peak and integrated photoluminescence
(PL) efficiency of the dots, up to a factor of 5–10 compared to as-grown samples, without any spectral shift of the luminescence
spectrum. The improved luminescence is attributed to the annealing of nonradiative point and extended defects in and around
the dots. 相似文献
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基于石墨烯/铟砷量子点/砷化镓异质结新型光电探测器 总被引:1,自引:1,他引:0
研究了一种石墨烯/铟砷量子点/砷化镓界面形成的异质结探测器的暗电流特性以及光电响应性质.虽然石墨烯具有很高的电子迁移率,但受限于较低的光子吸收率,使其在光电探测领域的应用受到了限制.而半导体量子点具有量子效率高,光吸收能力强等独特优点.于是利用石墨烯-砷化铟量子点-砷化镓异质结结构制备了一种新型光电探测器.并对该探测器的响应率、I-V特性曲线、暗电流特性、探测率、开关比等关键性能进行了研究.其在637 nm入射光情况下的响应率、探测率以及开关比可分别达到为17. 0 m A/W、2. 3×10~(10)cm Hz~(1/2)W~(-1)和1×10~3.而当入射光为近红外波段的940纳米时,响应率进一步增加到了207 m A/W.同时,还证实了该器件的暗电流、肖特基势垒高度和理想因子对温度的都具有较高的依赖性都较强. 相似文献