Reflection high-energy electron diffraction (RHEED) is a ubiquitous in situ molecular beam epitaxial (MBE) characterization tool. Although RHEED can be a powerful means for crystal surface structure determination, it is often used as a static qualitative surface characterization method at discrete intervals during a growth. A full analysis of RHEED data collected during the entirety of MBE growths is made possible using principle component analysis (PCA) and k-means clustering to examine significant boundaries that occur in the temporal clusters grouped from RHEED data and identify statistically significant patterns. This process is applied to data from homoepitaxial SrTiO3 growths, heteroepitaxial SrTiO3 grown on scandate substrates, BaSnO3 films grown on SrTiO3 substrates, and LaNiO3 films grown on SrTiO3 substrates. This analysis may provide additional insights into the surface evolution and transitions in growth modes at precise times and depths during growth, and that video archival of an entire RHEED image sequence may be able to provide more insight and control overgrowth processes and film quality.
Bibliographical noteFunding Information:
The authors would like to acknowledge the Auburn University Hopper Cluster for support of this work. The authors thank Matthew Brahlek and Jason Lapano for assistance with X-ray diffraction measurements. Scandate substrates were provided through the National Science Foundation [Platform for the Accelerated Realization, Analysis, and Discovery of Interface Materials (PARADIM)] Materials Innovation Platform under Cooperative Agreement No. DMR-1539918. S.T. and S.R.P. gratefully acknowledge support from the Auburn University Department of Physics. R.J.P. and R.B.C. gratefully acknowledge support for the work from NSF-DMR-1809847. Work at the UMN involving thin film growth and characterization was supported by the U.S. Department of Energy through DE-SC0020211.