Epitaxy, strain, and composition effects on metal-insulator transition characteristics of SmNiO3 thin films

SmNiO3 (SNO) thin films were deposited on LaAlO3 (LAO), SrTiO3, SrLaAlO4, Si, and Al2O3 (sapphire) substrates by RF magnetron sputtering and studies were conducted to understand how film structure and composition influence the insulator-metal transition properties. It is observed that the compressive strain induces the insulator to metal transition (MIT), while tensile strain suppresses it. In the case of non-epitaxial films, semiconducting behavior is obtained on sapphire over a broad temperature range, while on heavily-doped Si substrate; an MIT is seen in out-of-plane resistance measurement. In addition, thickness dependence on the resistance behavior and nickel oxidation state has been examined for epitaxial SNO films on LAO substrates. Fine control of the MIT by modifications to the mismatch strain and thickness provides insights to enhance the performance and the functionality of these films for emerging electron devices.