Atomistic and Continuum Modeling Strategies for Homoepitaxial Thin Film Growth

James Evans, Iowa State University

Homoepitaxial thin film growth reveals a rich variety of far-from-equilibrium morphologies. Atomistic lattice-gas models analyzed by KMC simulation have been most successful to date in predicting behavior observed in specific experiments. However, I shall also discuss 2D continuum formulations (level-set, phase-field, stochastic-geometry based) retaining discrete layers, and 3D continuum formulations for multilayer kinetic roughening.

Complete characterization of island formation during submonolayer deposition remains a basic challenge due to the failure of traditional mean-field formulations [1]. One goal of recent multiscale approaches is to efficiently and reliably treat the regime of highly reversible island formation. We discuss the special features of this regime and present results for the island size distribution obtained from the geometry-based simulation approach [2].

Step edge (SE) barriers inhibiting downward transport produce unstable multilayer growth characterized by mound formation. We analyze this phenomonon using realistic atomistic modeling to show that Ag/Ag(100) [regarded as the prototype for smooth growth due to a low SE barrier] actually grows very rough in the 100-1000 layer regime [3]. Furthermore, mound dynamics is more complex than predicted by standard 3D continuum models.

[1] PRB 54 (96) 17359;
[2] PRB 68 (03) 121401; SIAM MMS 3 (05);
[3] PRB 65 (02) 193407.