Structure Design and Development of Metal Oxide Superlattice as New Electronic Materials

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Metal oxides have gained much attention as new electronics materials because of their interesting properties which can not be accomplished by the silicon electronics materials. The atomic control of the metal oxide structure is a key technology for the development of their new functionality. Especially, in order to develop the metal oxide superlattice which have a novel function, the structure design on atomic level which is based on the accurate chemical and physical theories are essential. Hence, in the present study we elucidated the 2-dimensional epitaxial growth process of metal oxide superlattice by theoretical chemistry, as well as we investigated how we can construct atomically flat and smooth hetero-interface, which combination of atomic layers is stable, and what is a best buffer layer to construct ideal hetero-interface. Concretely, we developed a novel molecular dynamics program MOMODY, which can simulate the crystal growth process of metal oxide superlattice. By using the … More above simulator we clarified the crystal growth mechanism of metal oxide electronics materials, hetero-interface structure, relaxation process of lattice mismatch, surface reaction, and surface defects. Moreover, we succeeded in the design of the best buffer layer and best crystal growth condition. Especially, we clarified that the BaO/SrO is a best buffer layer for the YBCO/SrTiOィイD23ィエD2(001) interface. Furthermore, we elucidated that MgO quantum dots can be fabricated on the sapphire(0001) surface and the stability of several MgO Miller plane controls the structure of MgO thin films and quantum dots. Moreover, we developed coarse-grained crystal growth simulator and accelerated quantum chemical molecular dynamics programs which enable us to simulate the large system and chemical reaction dynamics, respectively. Some of the simulation results were confirmed by the experiments and the validity of our design was demonstrated. Finally we concluded that this project produced much amount of fruitful results for the development of atomically controlled metal oxide superlattice by the development and application of our newly developed theories and programs. Less