Direct imaging of single dopant atom in blue-light-emitting c-BN
Advanced electron microscopy reveals atomic-scale structure
Graduate School of Engineering / Faculty of Engineering
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 is 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.
Ryo Ishikawa, Naoya Shibata, Fumiyasu Oba, Takashi Taniguchi,
Scott D. Findlay, Isao Tanaka and Yuichi Ikuhara,
“Functional Complex Point-Defect Structure in a Huge-Size-Mismatch System”,
Phys. Rev. Lett. 110, 065504 (2013). doi: 10.1103/PhysRevLett.110.065504.