Cubic boron nitride is a promising system for photonics and optoelectronics. Determining the inclusion mechanisms for dopants with a large size mismatch, such as luminous rare-earth elements, is prerequisite to understanding their functional properties and to effective doping control.
In this study, Professor Yuichi Ikuhara, Associate Professor Naoya Shibata and their group at the University of Tokyo’s Graduate School of Engineering Institute of Engineering Innovation directly imaged individual Ce single dopant atoms inside a c-BN host crystal using an atomic-resolution scanning transmission electron microscope equipped with an aberration corrector.
It was found that Ce single atoms occupy the N sites but not B sites. Combining the experimental findings with first-principles calculations, the researchers discovered that the Ce atoms are forming a complex point-defect structure inside c-BN. This surprising result is the fundamental reason that very large Ce atoms can be accommodated inside c-BN crystals.
Paper: “Functional Complex Point-Defect Structure in a Huge-Size-Mismatch System”, Phys. Rev. Lett. 110, 065504 (2013). DOI: 10.1103/PhysRevLett.110.065504. Article link
Source: University of Tokyo