Understanding the Thermal Stability of Silver Nanoparticles Embedded in a-Si

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• 作者：Anna L. Gould ; Shima Kadkhodazadeh ; Jakob B. Wagner ; C. Richard A. Catlow ; Andrew J. Logsdail ; Marcel Di Vece
• 刊名：Journal of Physical Chemistry C
• 出版年：2015
• 出版时间：October 15, 2015
• 年：2015
• 卷：119
• 期：41
• 页码：23767-23773
• 全文大小：679K
• ISSN：1932-7455

文摘

The inclusion of silver plasmonic nanoparticles in silicon is highly relevant for photovoltaics as it may enhance optical absorption. We report an investigation of the stability of such pristine silver nanoparticles embedded in a-Si upon heat treatment. We have investigated the morphological changes via in situ and ex situ high-resolution and high-angle annular dark-field scanning transmission electron microscopy (HRTEM and HAADF STEM). The melting of Ag particles and subsequent interdiffusion of Ag and Si atoms are strongly related to the size of the Ag nanoparticles, as well as the presence of surface imperfections. Partial voids in the amorphous-Si framework are formed where sections of the Ag nanoparticles are found preferentially to diffuse away due to geometric instability. Computational simulations using ensemble molecular dynamics confirm the experimental results: the structural properties of the amorphous-Si environment are important as well as incomplete packing of the Ag nanoparticle surfaces. These factors affect the melting temperature, causing some parts of the Ag nanoparticles to dissolve preferentially and other areas to remain stable at high temperatures.