Photoelectron Diffraction and Holography Studies on Dopant Local Structures

Photoelectron holography (PEH) is an experimental technique that can be used to study the three-dimensional (3D) local structure around a focused atom. Recent advancements in reconstruction algorithm and the utilization of high-intensity soft X-rays generated from third-generation synchrotron facilities have made it possible to reveal detailed dopant local structures of less than 1% concentrations, with element and chemical site selectivities. Moreover, recent PEH studies have demonstrated that even the dopant occupancy for each crystal site of diamond and graphene can be estimated and that the orientation of a dopant vacancy complex can be determined. The information obtained by this technique is valuable for understanding and improving the physical properties of doped materials and also sheds light on how dopants are taken up in a crystal during synthesis. Here, photoelectron diffraction (PED) studies on dopant locations and recent PEH studies reporting detailed dopant local structures are reviewed, emphasizing the unique local structure information that can be obtained by this technique.