Atomic defects exist in various heterojunctions and can remarkably affect their properties, yet it remains a challenging task to identify each individual defect. Here, by combining advanced transmission electron microscopy, spectroscopy and first-principles calculations, we obtain a structural and element-selective imaging of defects at an interface between MgO and SrTiO3. We demonstrate that even for structurally simple MgO and SrTiO3, their interface involves a defect complex comprising of substitutional Ti and Mg vacancies, which induce a marked shift in electronic states. The Ti atoms diffused into MgO exhibit a valence state of +4 and a certain degree of covalency to the surrounding oxygen. Such an ability to determine defects allows us to precisely alter heterojunctions so as to critically improve the device performances.
ASJC Scopus subject areas
- Chemical Engineering(all)