Nucleation and growth kinetics for intercalated islands during deposition on layered materials with isolated point-like surface defects

Theory and stochastic lattice-gas modeling is developed for the formation of intercalated metal islands in the gallery between the top layer and the underlying layer at the surface of layered materials. Our model for this process involves deposition of atoms, some fraction of which then enter the gallery through well-separated point-like defects in the top layer. Subsequently, these atoms diffuse within the subsurface gallery leading to nucleation and growth of intercalated islands nearby the defect point source. For the case of a single point defect, continuum diffusion equation analysis provides insight into the nucleation kinetics. However, complementary tailored lattice-gas modeling produces a more comprehensive and quantitative characterization. We analyze the large spread in nucleation times and positions relative to the defect for the first nucleated island. We also consider the formation of subsequent islands and the evolution of island growth shapes. The shapes reflect in part our natural adoption of a hexagonal close-packed island structure. Motivation and support for the model is provided by scanning tunneling microscopy observations of the formation of intercalated metal islands in highly-ordered pyrolytic graphite at higher temperatures. Disciplines Condensed Matter Physics | Engineering Physics | Materials Chemistry | Materials Science and Engineering Authors Yong Han, Ann Lii-Rosales, Y. Zhou, C.-J. Wang, M. Kim, Michael C. Tringides, Cai-Zhuang Wang, Patricia A. Thiel, and James W. Evans This article is available at Iowa State University Digital Repository: http://lib.dr.iastate.edu/ameslab_manuscripts/26 PHYSICAL REVIEW MATERIALS 1, 053403 (2017) Nucleation and growth kinetics for intercalated islands during deposition on layered materials with isolated pointlike surface defects Yong Han,1,2 A. Lii-Rosales,1,3 Y. Zhou,1,4 C.-J. Wang,5 M. Kim,1,2 M. C. Tringides,1,2 C.-Z. Wang,1,2 P. A. Thiel,1,3,6 and James W. Evans1,2,7 1Ames Laboratory–USDOE, Iowa State University, Ames, Iowa 50011, USA 2Department of Physics and Astronomy, Iowa State University, Ames, Iowa 50011, USA 3Department of Chemistry, Iowa State University, Ames, Iowa 50011, USA 4Department of Physics, Xiamen University, Xiamen 361005, China 5Department of Mathematics, National Chung Cheng University, Chiayi 62102, Taiwan 6Department of Materials Science and Engineering, Iowa State University, Ames, Iowa 50011, USA 7Department of Mathematics, Iowa State University, Ames, Iowa 50011, USA (Received 8 June 2017; revised manuscript received 14 August 2017; published 13 October 2017) Theory and stochastic lattice-gas modeling is developed for the formation of intercalated metal islands in the gallery between the top layer and the underlying layer at the surface of layered materials. Our model for this process involves deposition of atoms, some fraction of which then enter the gallery through well-separated pointlike defects in the top layer. Subsequently, these atoms diffuse within the subsurface gallery leading to nucleation and growth of intercalated islands nearby the defect point source. For the case of a single point defect, continuum diffusion equation analysis provides insight into the nucleation kinetics. However, complementary tailored lattice-gas modeling produces a more comprehensive and quantitative characterization. We analyze the large spread in nucleation times and positions relative to the defect for the first nucleated island. We also consider the formation of subsequent islands and the evolution of island growth shapes. The shapes reflect in part our natural adoption of a hexagonal close-packed island structure. Motivation and support for the model is provided by scanning tunneling microscopy observations of the formation of intercalated metal islands in highly-ordered pyrolytic graphite at higher temperatures. DOI: 10.1103/PhysRevMaterials.1.053403