Mechanisms and Dynamics of Layered Structure Formation During Co-Deposition of Binary Compound Thin Films

• Main Authors: Gediminas Kairaitis, Arvaidas Galdikas
• Format: Article
• Language: English
• Published: MDPI AG 2019-12-01
• Series: Coatings
• Subjects: phase separation; surface segregation; kinetic modeling; thin films; multilayer
• Online Access: https://www.mdpi.com/2079-6412/10/1/21

In the present paper, the formation of columnar and layered structure during co-deposition of binary thin films is analyzed by kinetic modeling. The kinetic model is based on phase field theory and involves the main processes taking place during binary film growth: adsorption, phase separation, Gibbsian surface segregation, surface and bulk diffusion. The process of phase separation is defined by the Cahn−Hilliard equation, which describes well the kinetics of formation of nanoparticles in binary system with a limited solubility of components. The formation of columns and layers can occur only if other processes such as diffusion and segregation take place. In this paper, the most attention is paid to the formation of multilayered structures during binary components co-deposition, which is experimentally observed, but whose mechanism of formation is not well understood. In the work presented, the mechanism of formation of layers is shown, and the conditions at which this mechanism starts to work are formulated. It is shown that very important aspects are surface segregation of one of the components and depth dependent diffusion.