Anion exchange at the interfaces of mixed anion III-V heterostructures grown by molecular beam epitaxy
Brown, Terence D.
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The objective of this research was to investigate the microscopic processes occurring at the interfaces of mixed anion III-V heterostructures grown by molecular beam epitaxy (MBE). In particular, efforts were made to characterize the dominant chemical and physical mechanisms that lead to anion exchange and to develop semi-empirical models capable of predicting the atomic scale structure and composition at the interfaces of mixed anion heterostructures for the As/P and Sb/As material systems. This research considers the MBE growth of 20-period superlattices (SLs) formed by allowing a dissimilar anion flux to impinge on a static group-V stabilized surface. Statistical experimental design was used to determine the effects of substrate temperature, V/III growth flux ratio, and anion exposure time on the anion exchange process. The superlattice structures were analyzed via high resolution x-ray diffraction (HRXRD) and simulation, RHEED analysis, x-ray photoelectron spectroscopy (XPS), and other techniques, which allowed for the determination of both chemical composition and atomic structure at the interfaces. Finally, a semi-empirical hybrid neural network was developed that quantifies the effects of MBE growth processes at the interfaces of mixed anion III-V heterostructures by incorporating a first principles kinetic model with back-propagation neural networks.