Auger electron spectroscopy and transmission electron microscopy were applied to understand the grain boundary phenomena of ZnO and SrTiO3. The interface structure of SrTiO3 bicrystals was analyzed by molecular dynamics method; peculiar local configurations around the interfaces and their electronic states were investigated in relation to the formation of interfacial states. Regards ZnO grain boundaries, molecular orbital calculation was adopted for the elucidation of chemical bonding state and frontier electron state.
