Surfactant-Mediated Surface Growth: Nonequilibrium Theory

TL;DR

This paper develops a nonequilibrium theoretical model describing how surfactants influence epitaxial film growth, potentially leading to smoother, flat surfaces by modifying growth dynamics.

Contribution

It introduces coupled equations based on experimental characteristics and symmetry principles to model surfactant effects on surface growth.

Findings

Surfactants can induce a phase with negative surface roughness.

The model predicts surfactant-driven transition to flat surface growth.

Scaling relations between roughness exponents are derived.

Abstract

A number of recent experiments have showed that surfactants can modify the growth mode of an epitaxial film, suppressing islanding and promoting layer-by-layer growth. Here a set of coupled equations are introduced to describe the coupling between a growing interface and a thin surfactant layer deposited on the top of the nonequilibrium surface . The equations are derived using the main experimentally backed characteristics of the system and basic symmetry principles. The system is studied using a dynamic-renormalization-group scheme, which provides scaling relations between the roughness exponents. It is found that the surfactant may drive the system into a novel phase, in which the surface roughness is negative, corresponding to a flat surface.