Abstracts Book - IMRC 2018

• SF2-O001 Invited Talk
CRYSTAL GROWTH PHENOMENA OF CHALCOGENIDE
MULTILAYERS WITH ATOMIC-SCALE RESOLUTION VIA
MOLECULAR DYNAMICS
David Zubia 1 , Rodolfo Aguirre 1 , Jose Juan Chavez 2 , Sharmin Abdullah 3 , Xiaowang Zhou 2
1 The University of Texas at El Paso, Electrical and Computer Engineering, United States. 2 Sandia
National Laboratories, Mechanics of Materials Department, United States. 3 The University of
Texas at El Paso, Computational Science Department, United States.
Important crystal growth phenomena of single- and poly-crystalline
chalcogenide multilayers are studied with atomic-scale resolution using
molecular dynamics. Studying the growth evolution of chalcogenide multilayers
with atomic scale resolution is crucial for the development of infrared imaging,
radiation detectors, and photovoltaic devices. Molecular dynamics is a powerful
simulation technique that essentially solves Newton’s equation of motion for a
system containing 100s of thousands of atoms. The technique yields threedimensional
information of atom positions as a function of time. This enables
visualization of crystal and defect evolution. The molecular dynamics capability
used in this work is based on a Stillinger-Weber potential and is able to simulate
Zn, Cd, S, Te, Cu, Se, and Hg giving it wide latitude to study a variety of material
stacks and deposition conditions. Time-resolved 3D visualizations of any region
within the material stack can be used to investigate crystalline and defect
structure evolution. In this work, atom diffusion, grain boundary migration and
dislocation dynamics are studied in single- and poly-crystalline films. Predicted
crystal and defect structures are shown to be in remarkable agreement with
experimental results. Atom diffusion through defected and pristine regions are
analyzed. It is observed that grain boundaries and stacking faults act as
transport channels for diffusing atoms. Secondly, propagation of Σ3, Σ7, and Σ11
coincidence-site lattice and stacking fault grain boundaries in single and
polycrystalline films is investigated. Thermally activated grain boundary
migration is observed; however, boundary character has a strong influence on
mobility. Finally, dislocation interactions are also studied during crystal growth.
It is observed that dislocation interactions nucleate at crystal surfaces and
interfaces and propagate much faster than the growth rate. Videos of the
dislocation evolution are presented showing fascinating misfit and threading
dislocation interaction dynamics. These insights are useful to interpret
experimental results and guide future investigations.