Three-Dimensional Imaging of a Single Dopant in a Crystal

Single dopants in materials have strong influences on the fundamental properties in extensive fields. Annular dark-field scanning tranmission electron microscopy (ADF STEM) has been contributed to directly investigate the occupation site of single dopants and their spatial distributions at atomic scale. However, the resultant atomic resolution images are projected in two dimensions, lacking in depth information. Here, we demonstrate the direct determination of three-dimensional atomic locations of single Ce dopants embedded in cubic boron nitride by ADF STEM depth sectioning with a significantly large illumination angle of 63 mrad in semiangle. Furthermore, we directly evaluate the Ce-Ce partial pair distribution function in the considerably long distance up to 8.5 nm, which opens the way to study a far-long-range interaction between impurities especially in a dilute doping system.