(649a) Microscopic Modeling of a Two-Species Thin Film Deposition Process Arising in Transparent Conducting Oxide Layer Manufacturing

Thin film solar cells constitute an important and growing
component of the overall solar cell market owing to their potential of
yielding improved light conversion efficiencies. The Transparent
Conducting Oxide (TCO) layer, which typically consists of zinc oxide (ZnO)
and aluminum (Al), is an important component of thin film solar cells and has
a crucial influence on the performance of thin film solar cell systems. In addition to
investigating the performance with respect to light conversion efficiency and
long-term stability of an array of materials, thin film solar cell
technology stands to benefit from fundamental microscopic modeling and optimal thin film
manufacturing (deposition) control strategies that
produce thin films with desired light trapping properties.
This work focuses on the modeling of a large-scale two-species thin film
deposition process and its application in the manufacturing process of TCO layers.
Aggregate surface roughness and slope are
introduced to characterize the properties of TCO thin film surface
properties. Both kinetic Monte Carlo (kMC) models and stochastic partial differential equation
(SPDE) models are introduced to describe the film surface morphology
dynamics. In the kMC models, a solid-on-solid square lattice is used to simulate the process and
different growth mechanisms are utilized for each component, zinc oxide (ZnO) and
aluminum (Al). Specifically, a deposition/migration mechanism is used for
ZnO and a random deposition with surface relaxation mechanism
is used for Al. In SPDE models, an Edwards-Wilkinson type equation is used to
predict the process dynamics, which can be used in future work to design a
feedback controller. Extensive simulation results will be presented to elucidate
the dynamic behavior of surface morphology and pave the
way for model-based feedback control.