Three-dimensional dopant imaging in semiconductor crystals using photoelectron holography with chemical state identification

Doping is an important technology for modern science. For example, to create a semiconductor device, a circuit is formed by controlling carriers by doping. It is important to search for appropriate conditions since the carrier emission from dopant differs depending on the doping conditions. The atomic arrangement around the dopant differs depending on the conditions. Therefore, it has been desired to observe the atomic arrangement around the dopant, but it has been difficult with conventional measurement methods. The atomic resolution holography such as photoelectron holography, X-ray fluorescence holography, neutron holography, which are methods that can measure the three-dimensional (3D) atomic arrangement of the dopant. Among them, photoelectron holography can measure the atomic structure of each dopant depending on the chemical state. We have built photoelectron holography apparatuses at BL25SU in SPring-8. We also developed a software platform 3D-AIR-IMAGE for data processing, simulation of photoelectron holograms, and 3D atomic image reconstruction.