Epitaxial SrTaO3 and Heterostructures Grown by Hybrid Molecular Beam Epitaxy

SrTaO3, a metallic perovskite oxide, possesses invaluable properties such as large SOC, high mobility, large magnetoresistance, and transparency. Integration into heterostructures can induce distinctive states and properties, including 2DEGs and topological states. While SrTaO3 has been grown previously by methods such as solid-state reactions and PLD, these methods can lead to various defects (e.g., chemical impurities or dislocations), which can hinder optimization or realization of the intended phenomena. MBE offers a route to synthesis of thin films with precise control of stoichiometry, lattice structure, and defect mitigation. Due to the high melting point of elemental tantalum and its propensity to overoxidize from the desired Ta4+ to Ta5+, the material was grown by hybrid MBE using a nitrogenous organometallic precursor. Characterization by in-situ reflection high energy electron diffraction and x-ray photoelectron spectroscopy, as well as ex-situ high resolution XRD, electrical transport, and STEM was undertaken to confirm the formation of epitaxial SrTaO3. Following successful implementation of single-layer SrTaO3, various (SrCoO3)m/( SrTaO3)n heterostructures were grown to probe the emergent interfacial and superlattice states.