Title:	Computational studies of thin metal film growth on weakly-interacting 2D substrates
DNr:	SNIC 2022/5-144
Project Type:	SNIC Medium Compute
Principal Investigator:	Konstantinos Sarakinos <kosa@kth.se>
Affiliation:	Kungliga Tekniska högskolan
Duration:	2022-03-29 – 2022-10-01
Classification:	10304
Keywords:

Abstract

The goal of the project is to study, by means of deterministic (non-equilibrium ab initio molecular dynamics) and stochastic (kinetic Monte-Carlo), simulations the initial stages of thin metal film growth on weakly-interacting 2D substrates. Atoms deposited from the vapor phase on weakly-interacting substrates self-assemble in dispersed three-dimensional (3D) nanoscale islands (i.e., nanostructures). A notable example is the deposition of metal films on two-dimensional (2D) crystals (e.g., graphene and MoS2) and functional oxides (e.g., ZnO and TiO2) for which the tendency toward the formation of 3D agglomerates imposes technological obstacles for the use of advanced materials in a wide range of energy, catalytic, sensing, and switching devices. Thus, understanding the currently unknown atomistic mechanisms that govern 3D island formation and shape evolution is a key step toward controlling film morphology and, by extension, the functionality of devices based on weakly-interacting film/substrate materials systems. Over the past few years, we have carried out theoretical studies on the growth of thin metal films on weakly-interacting oxide and 2D material substrates using an in-house kinetic Monte-Carlo (kMC) algorithm and ab initio molecular dynamics simulations. Our results reveal possible pathways and mechanisms for 3D island formation, and provided new insights into the very initial stages of film formations. The goal of this project is to build upon the knowledge we have generated and the results we have achieved and continue modelling initial and late stages of noble-metal (e.g., Ag, Au, and Pd) film formation on model MoS2, TiO2, and ZnO surfaces. Our previously developed kMC code will be used as starting point and it will refined and augmented as detailed below: (1) We will use DFT calculations to determine surface adsorption energies and diffusion barriers of metal adatoms on MoS2, TiO2, and ZnO. (2) We will also employ non-equilibrium ab initio molecular dynamics simulations (modified version of VASP developed by us (Sangiovanni et al. PhysRevB 93, 094305 (2016)), to investigate atomistic processes and dynamics during the initial stages of film island nucleation and growth and improve the accuracy of KMC simulations. Publications from our group where use of SNIC resources is acknowledged: Smirnova et al., Phys. Rev. Mat. 4, 013605 (2020) Zarshenas et al., Phys. Chem. Chem. Phys. 23, 13087(2021) Gervilla et al., J. Phys. Chem. Lett. 11 (2020) 8930. Gervilla et al., Sci. Rep. 10 (2020) 2031. Sangiovanni et al., Physical Review Materials 4, 033605 (2020) Mei et al., Acta Materialia 192, 78 (2020) Kakanakova-Georgieva et al., Nanoscale 12, 19470 (2020) Kakanakova-Georgieva et al., CrystEngComm 10.1039/D0CE01426E Mikula et al, Surface and Coatings Technology 405, 126723 (2021)