| Summary: | We demonstrate the making of BaZrS3 thin films by molecular beam epitaxy (MBE). BaZrS3
forms in the orthorhombic distorted-perovskite structure with corner-sharing ZrS6 octahedra. The
single-step MBE process results in films smooth on the atomic scale, with near-perfect BaZrS3
stoichiometry and an atomically-sharp interface with the LaAlO3 substrate. The films grow
epitaxially via two, competing growth modes: buffered epitaxy, with a self-assembled interface
layer that relieves the epitaxial strain, and direct epitaxy, with rotated-cube-on-cube growth that
accommodates the large lattice constant mismatch between the oxide and the sulfide perovskites.
This work sets the stage for developing chalcogenide perovskites as a family of semiconductor
alloys with properties that can be tuned with strain and composition in high-quality epitaxial thin
films, as has been long-established for other systems including Si-Ge, III-Vs, and II-Vs. The
methods demonstrated here also represent a revival of gas-source chalcogenide MBE.
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