Suyong Kim
Seoul National University · Engineering
About the Lab
Professor Suyong Kim's research lab specializes in advanced functional materials, with a focus on defect engineering, ferroelectricity, and surface science for next-generation electronic and energy applications. The lab investigates the role of defects and polarization in perovskite and ferroelectric materials to enhance device performance, particularly in solar cells and high-density memory devices. Using advanced characterization techniques such as high-resolution XPS and in-situ spectroscopy, the group explores electronic structures and surface reactions on single-crystalline substrates, especially Pt-based systems, to understand and control catalytic and electronic properties at the atomic level. Their work bridges fundamental materials physics with practical applications in energy conversion and nanoelectronics.
Research Overview
Research Output Trend
Figures are computed from collected data and may differ slightly.
Selected Papers
15We report the presence of defects in CH<sub>3</sub>NH<sub>3</sub>PbI<sub>3</sub>, which is one of the main factors that deteriorates the performance of perovskite solar cells.
Multilevel non-volatile memory for high-density date storage is achieved by using the deterministic control of ferroelectric polarization. In a real ferroelectric thin-film system, eight stable and reproducible polarization states are realized (i.e., 3-bit data storage) by adjusting the displacement current. This approach can be used to triple or quadruple the memory density, even at existing feature scales.
We present a method for decoupling epitaxial graphene grown on SiC(0001) by intercalation of a layer of fluorine at the interface. The fluorine atoms do not enter into a covalent bond with graphene but rather saturate the substrate Si bonds. This configuration of the fluorine atoms induces a remarkably large hole density of p ≈ 4.5×10<sup>13</sup> cm<sup>-2</sup>, equivalent to the location of the Fermi level at 0.79 eV above the Dirac point ED.
Active control of defect structures and associated polarization switching in a ferroelectric material is achieved without compromising its ferroelectric properties. Based on dipolar interaction between defect dipole and polarization, the unique functionality of the defect dipole to control ferroelectric switching is visualized. This approach can provide a foundation for novel ferroelectric applications, such as high-density multilevel data storage.
Revealing the electronic structures of Pt-alloys explains why the addition of transition metal to Pt speeds up the oxygen reduction reaction. It is found that transition metals in the subsurface induce charge polarization at the surface and suppresses the surface-states. The modified surface-states of Pt surface layer critically affects the chemical bonding between oxygen and Pt surfaces.
By using high resolution x-ray photoelectron spectroscopy, we show that inelastic scattering of photoelectron at low temperature (30-50 K) generates two kinds of oxygen species on Pt (111) surface. Intense synchrotron radiation source dissociates oxygen molecules into chemisorbed atomic oxygen and induces the formation of PtO on the surface. Estimated coverage of dissociated atomic oxygen is 0.5 ML, suggesting possible formation of p(2 x 1) surface structure, while PtO coverage shows saturation
In practical applications to bipolar resistance switching (BRS) memory devices with enhanced performance and high-scalability, oxide materials are commonly fabricated to highly nonstoichiometric and nanometer scale films. In this study, we fabricated ultrathin strontium titanate film, which shows two types of BRS behavior. By using micro-beam X-ray photoemission spectroscopy, the changes of core-level spectra depending on the resistance states are spatially resolved. Experimental and calculated
We investigate room-temperature (RT) ferroelectricity in tensile-strained SrTiO3 (STO) thin films grown on GdScO3 (110) substrates. To separate the strain and the defect dipole effect, we apply an electric field to measure the polarization in the direction perpendicular to the elongation axis, and the RT ferroelectric polarization is found to be perpendicular to that axis. These results clearly demonstrate the importance of the contribution of defect dipoles to the RT ferroelectricity observed i
We report on the chemical adsorption mechanism of atomic oxygen on the Pt(111) surface using angle-resolved-photoemission spectroscopy (ARPES) and density functional calculations. The detailed band structure of Pt(111) from ARPES reveals that most of the bands near the Fermi level are surface-states. By comparing band maps of Pt and O/Pt, we identify that dxz (dyz) and dz(2) orbitals are strongly correlated in the surface-states around the symmetry point M and K, respectively. Additionally, we d
To employ Li-based batteries to their full potential in a wide range of energy-storage applications, their capacity and performance stability must be improved. Si is a viable anode material for Li-based batteries in electric vehicles due to its high theoretical capacity and good economic feasibility. However, it suffers from physical and chemical degradation, leading to unstable electrochemical performance and preventing its incorporation in new Li-based battery systems. Herein, we applied a pol
The bevel structure of organic multilayers produced by finely controlled Ar gas cluster ion beam sputtering preserves both the molecular distribution and chemical states. Nevertheless, there is still an important question of whether this method can be applicable to organic multilayer structures composed of complex or ambiguous interfaces used in real organic optoelectronic devices. Herein, various bevel structures are fabricated from different types of organic semiconductors using a solution-bas
Research Areas
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