The photochemical growth of silver nanoparticles on semiconductor surfaces—initial nucleation stage
The photochemical growth of silver nanoparticles on semiconductor surfaces—initial nucleation stage
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DOI：
10.1088/0957-4484/20/11/115604
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发表时间：
2009-03
期刊：
影响因子：
3.5
通讯作者：
Steve Dunn;S. Sharp;S. Burgess
中科院分区：
文献类型：
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作者：
Steve Dunn;S. Sharp;S. Burgess
围绕使用光化学技术在半导体（例如锆钛酸铅）上生长的纳米结构的成核机制的问题包括“什么是成核过程？”到“有可能产生均匀的纳米级图案吗？”。在这里，我们证明，成核发生在离散的位置上的衬底的表面上，这是指示的中断的局部斯特恩层由于在衬底中的局部缺陷或电场。该系统的能带图是这样的，当形成团簇时，电子可以迁移到银金属中，从而用局部负电荷取代与铁电体的正畴相关的表面正电荷。一旦初始团簇开始形成，单个团簇的生长速率由于Stern层的重组以及电子与溶液中阳离子反应的可能性增加而增加。我们发现，成核密度并没有显着改变从初始成核密度，并且大约15%的颗粒，形成在表面上的50%比其他颗粒大。成核密度没有显着变化的原因干从可用的中断位置的斯特恩层的浓度，并在生长速率的变化进行了讨论的局部电场和缺陷的影响。
Questions surrounding the nucleation mechanism for nanostructures that are grown on semiconductors, such as lead zirconate titanate, using photochemical techniques have ranged from ‘What is the nucleation process?’ to ‘Is it possible to produce homogeneous nanoscale patterns?’. Here we demonstrate that nucleation occurs at discrete locations on the surface of the substrate that are indicative of a disruption of the local Stern layer due to a local defect or electric field in the substrate. The band diagram for the system is such that when a cluster forms it is possible for electrons to migrate into the silver metal and so replace the surface positive charge, associated with the positive domain of the ferroelectric, with a local negative charge. Once the initial cluster starts to form, the rate of growth of an individual cluster increases due to a restructuring of the Stern layer and increased probability of reaction of an electron with the cations in solution. We show that the nucleation density does not change significantly from the initial nucleation density, and that approximately 15% of the particles that form on the surface are 50% larger than the other particles. The reasons for no significant change in nucleation density stem from the concentration of available disrupted locations in the Stern layer, and variations in the growth rate are discussed in terms of the local electric field and defect influences.