Materials with temperature-dependent metal-to-insulator transitions (MIT) have gained attention for the abrupt collapse of the band gap during the transition. Various novel transistor structures which utilize MITs have been suggested and realized to produce more energy efficient transistors. To achieve practical operation temperatures for device applications, however, MIT materials with transition temperatures below 400 K are unsuitable. This work focuses on one MIT material with a high

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... ure transition, LaCoO 3 . Using oxide molecular-beam epitaxy (MBE) a series of LaCoO 3-x thin films with varied La and Co compositions were grown. All films were grown on LaAlO 3 (001) p substrates, which like LaCoO 3 , has a pseudocubic perovskite structure. The lattice mismatch is less than 0.9%. X-ray diffraction θ-2θ measurements were used to assess the structure of the films; the out-of-plane lattice constant of each film was calculated using a Nelson-Riley analysis. The temperature-dependent resistivity of each film was measured and each shows a change in electrical resistivity of more than two orders of magnitude in the MIT temperature range of 400 -600 K, which is similar to that of bulk single crystal LaCoO 3 . The abruptness and magnitude of the MIT is found to be insensitive to the film composition for samples ranging from La 1.1 CoO 3-x to LaCo 1.1 O 3-x . iii BIOGRAPHICAL SKETCH Lindsey E. Noskin received her Bachelor of Science degree from Cornell University in May of 2017 with a thesis entitled, "Growth of NbO 2 by Molecular-Beam Epitaxy and Characterization of its Metal-Insulator Transition." During her undergraduate career, she spent one semester on the Neubauer Exchange Program at the Technion in Haifa, Israel. As an undergraduate student, Lindsey was given the Milton Fisher Scholarship for Innovation and Creativity and was a Hunter R. Rawlings III Cornell Presidential Research Scholar. Upon acceptance to the accelerated Master of Science program offered by the department of Materials Science and Engineering at Cornell, Lindsey was also awarded the Intel Corporation/Semiconductor Research Corporation Fellowship for her Master's Degree.