# Predicting Pulsed-Laser Deposition SrTiO3 Homoepitaxy Growth Dynamics Using High-Speed Reflection High-Energy Electron Diffraction

## TL;DR

Researchers developed a high-speed method to study how materials grow using laser deposition, revealing new insights into surface dynamics.

## Contribution

A high-speed RHEED platform and open-source analysis tool are introduced to study PLD growth dynamics at >500 Hz.

## Key findings

- High-speed RHEED captures single-pulse surface reconstruction kinetics previously obscured by slower systems.
- Surface termination and step width affect diffraction intensity decay and adatom deposition rates.
- The method enables real-time insights into growth mechanisms with implications for machine learning and autonomous control.

## Abstract

Pulsed-laser deposition (PLD) is a powerful technique
for growing
complex oxides with controlled stoichiometry. To understand growth
dynamics therein, it is common to leverage in situ spectroscopies, such as reflection high-energy electron diffraction
(RHEED), to monitor surface crystallinity. Most commercial systems
rely on video-rate cameras operating at 60–120 Hz that lack
sufficient temporal resolution to capture growth dynamics at practical
deposition frequencies. Here, a high-speed platform to record in situ dynamics via RHEED at >500 Hz is implemented.
An
open-source analysis package is designed to fit diffraction spots
to 2D Gaussians, allowing single-pulse surface reconstruction kinetics
extraction. Using homoepitaxially deposited (001)-oriented SrTiO3 as a model system, we demonstrate how high-speed RHEED can
provide real-time insight into growth processes obscured by slower
acquisition systems. By fitting the single-pulse intensity to a set
of exponential functions, we observe changes in the characteristic
decay time and mechanism correlated to the substrate step width and
surface termination. We observe distinct surface effects, with diffraction
intensity decaying on lower-energy TiO2-terminated surfaces
and stabilizing on SrO- or mixed-terminated surfaces. Similarly, using
an exponential model, the extracted characteristic time of adatom
deposition decreases with increased density of bonding sites associated
with mixed termination and narrower step widths. Ultimately, this
work shows how increasing RHEED temporal resolution can uncover new
insights into growth processes, with practical implications for the
design and control of PLD processes. This experimental platform provides
new capabilities to enable data-driven machine learning analysis and
autonomous control systems to enhance the complexity and fecundity
of PLD.