Jansson Ville, Baibuz Ekaterina, Kyritsakis Andreas, Vigonski Simon, Zadin Vahur, Parviainen Stefan, Aabloo Alvo, Djurabekova Flyura
Helsinki Institute of Physics and Department of Physics, P.O. Box 43, (Pehr Kalms gata 2), FI-00014, University of Helsinki, Helsinki, Finland.
Nanotechnology. 2020 Aug 28;31(35):355301. doi: 10.1088/1361-6528/ab9327. Epub 2020 May 14.
In this work we show using atomistic simulations that the biased diffusion in high electric field gradients creates a mechanism whereby nanotips may start growing from small surface asperities. It has long been known that atoms on a metallic surface have biased diffusion if electric fields are applied and that microscopic tips may be sharpened using fields, but the exact mechanisms have not been well understood. Our Kinetic Monte Carlo simulation model uses a recently developed theory for how the migration barriers are affected by the presence of an electric field. All parameters of the model are physically motivated and no fitting parameters are used. The model has been validated by reproducing characteristic faceting patterns of tungsten surfaces that have in previous experiments been observed to only appear in the presence of strong electric fields. The growth effect is found to be enhanced by increasing fields and temperatures.
在这项工作中，我们通过原子模拟表明，在高电场梯度下的偏向扩散产生了一种机制，通过该机制纳米尖端可能从小的表面粗糙度处开始生长。长期以来，人们已经知道，如果施加电场，金属表面的原子会有偏向扩散，并且微观尖端可以通过电场来锐化，但确切的机制尚未得到很好的理解。我们的动力学蒙特卡罗模拟模型使用了一种最近开发的理论，该理论描述了迁移势垒如何受到电场存在的影响。模型的所有参数都基于物理原理，未使用拟合参数。该模型已通过再现钨表面的特征刻面图案得到验证，这些图案在先前的实验中被观察到仅在强电场存在时才会出现。研究发现，通过增加电场和温度，生长效应会增强。
