A stochastic model of solid state thin film deposition: application to chalcopyrite growth

TL;DR

This paper introduces a mesoscale stochastic model for solid state thin film growth, capturing inhomogeneities and reactions with the atmosphere, demonstrated on chalcopyrite photovoltaic film deposition.

Contribution

It presents a novel stochastic modeling approach that accounts for inhomogeneities in thin film growth, specifically applied to chalcopyrite photovoltaic materials.

Findings

Model explains composition variations in chalcopyrite films

Captures inhomogeneities and agglomerations in film growth

Applicable to various semiconductor and energy materials

Abstract

Developing high fidelity quantitative models of solid state reaction systems can be challenging, especially in deposition systems where, in addition to the multiple competing processes occurring simultaneously, the solid interacts with its atmosphere. In this work, we develop a model for the growth of a thin solid film where species from the atmosphere adsorb, diffuse, and react with the film. The model is mesoscale and describes an entire film with thickness on the order of microns. Because it is stochastic, the model allows us to examine inhomogeneities and agglomerations that would be impossible to characterize with deterministic methods. We demonstrate the modeling approach with the example of chalcopyrite Cu(InGa)(SeS)$_2$ thin film growth via precursor reaction, which is a common industrial method for fabricating thin film photovoltaic modules. The model is used to understand how and why through-film variation in the composition of Cu(InGa)(SeS)$_2$ thin films arises and persists. We believe that the model will be valuable as an effective quantitative description of many other materials systems used in semiconductors, energy storage, and other fast-growing industries.