Advanced Electron Microscopy
& Functional Imaging Lab
Si-Young Choi (Material Science and Engineering)
An atom is the smallest component of an element and consists of a nucleus with several electrons that orbit around it. A nucleus contains protons and neutrons, and the number of protons, neutrons and electrons determines the properties of an atom. Not only the quantity, but also the layout of these three basic particles affects an atom. To provide a comparison, think of how we often perceive gold as a yellowish colored solid. However, when this same gold is ground into fine powder, it becomes blue and then it becomes red. Not just its color, but also its conductivity and other characteristics change. Unfortunately, the inner dimensions of an atom which serve as a reliable glimpse into its properties remain quite a mystery in most materials.
The Advanced Electron Microscopy & Functional Imaging Laboratory (AEFI Lab) headed by Professor Si-Young Choi at the Department of Material Science and Engineering, POSTECH, observes atoms and electrons on the microscopic level to delve right to the core nature of a material. The Lab seeks to develop useful materials that can be viewed with the naked eye. Researchers at the Lab call this ‘material imaging’, whose name lends itself to the intention of examining atoms and electrons just as easily as we view a photograph.
Material imaging research basically requires transmission electron microscopy (TEM). A transmission electron microscope is a cutting-edge device where a high-voltage beam of electrons is transmitted through a specimen to form an image of its inner structure. The image is then magnified hundreds of thousands of times to enable researchers to observe the specimen. With its nanometer-level resolution (1 nm = one billionth of a meter), TEM enables highly sophisticated observations at the atomic level. The AEFI Lab embraced an AI-enabled machine learning model to improve the accuracy of analyzing the structural data of atoms by nearly five times to that of microscopes alone.
Such an achievement led to great success in unraveling the mystery of structural elucidation on two materials: Mn3GaN is capable of elaborately controlling the pathway of electrons and helps improve the performance of semiconductors that continue to get more and more tiny, and CaTi03, a perovskite-structured oxide, is drawing attention for its exceptional photoelectron properties that discover applications for solar cells and light-emitting devices. These research findings were featured in the international academic journals of ‘Science Advances’ in July and ‘Nature Communications’ in October of last year.
The research team plans to focus on building on its analytical competency to better understand the target material based on material imaging outcomes, in addition to developing analysis competency required for material imaging. While the Lab is definitely not first to arrive on the global stage, it aims to one day enlarge its influence beyond the nation and emerge as a world-renowned leading lab and progress along with the younger generations of researchers in the new materials sector. With this plan and goal in mind, the AEFI Lab will leverage its material imaging technology to understand the unique physical phenomena that manifests itself in new materials and continue on to lay the foundation to design novel materials.
Head of Lab