Pohang University of Science and Technology · Engineering
Professor Sangsul Lee's research lab specializes in advanced materials characterization using synchrotron radiation techniques, with a focus on energy storage materials and nanofabrication. The lab investigates cathode materials for lithium-ion batteries through X-ray absorption spectroscopy and X-ray diffraction, aiming to understand electrochemical behavior at the electronic and structural levels. Additionally, the lab explores extreme ultraviolet (EUV) lithography for next-generation semiconductor patterning, addressing challenges such as mask shadowing and critical dimension uniformity. The integration of advanced X-ray instrumentation and in-situ spectroscopic methods enables high-resolution chemical and electronic imaging of functional materials.
Figures are computed from collected data and may differ slightly.
Feature detection is important in various mesh processing techniques, such as mesh editing, mesh morphing, mesh compression, and mesh signal processing. In spite of much research in computer vision, automatic feature detection even for images still remains a difficult problem. To avoid this difficulty, semi-automatic or interactive techniques for image feature detection have been investigated. In this paper, we propose a geometric snake as an interactive tool for feature detection on a 3D triang
Herein, we report the soft X-ray absorption spectroscopic investigation for Li(Ni<sub>0.8</sub>Co<sub>0.1</sub>Mn<sub>0.1</sub>)O<sub>2</sub> cathode material during charging and discharging. These measurements were carried out at the Mn <i>L</i>-, Co <i>L</i>-, and Ni <i>L</i>-edges during various stages of charging and discharging. Both the Mn and Co <i>L</i>-edge spectroscopic measurements reflect the invariance in the oxidation states of Mn and Co ions. The Ni <i>L</i>-edge measurements show
Investigations to evaluate the extreme ultraviolet (EUV) lithographic performance of 160 nm thick poly(methyl methacrylate) with 13.5 nm wavelength EUV light were performed using a synchrotron radiation source at Pohang Light Source-II (PLS-II). The single system enabled the determination of the sensitivity, contrast, linear absorption coefficient, critical dimension, and line edge roughness of polymer thin films through tests and measurements. The experimental findings were also compared to the
Li-ion rechargeable batteries are promising systems for large-scale energy storage solutions. Understanding the electrochemical process in the cathodes of these batteries using suitable techniques is one of the crucial steps for developing them as next-generation energy storage devices. Due to the broad energy range, synchrotron X-ray techniques provide a better option for characterizing the cathodes compared to the conventional laboratory-scale characterization instruments. This work gives an o
For spectral imaging of chemical distributions using X-ray absorption near-edge structure (XANES) spectra, a modified double-crystal monochromator, a focusing plane mirrors system and a newly developed fluorescence-type X-ray beam-position monitoring and feedback system have been implemented. This major hardware upgrade provides a sufficiently stable X-ray source during energy scanning of more than hundreds of eV for acquisition of reliable XANES spectra in two-dimensional and three-dimensional
The mask shadowing effect is a unique phenomenon caused by a mirror-based mask structure and an oblique incident angle of light in the extreme ultraviolet lithography process. This results in a horizontal–vertical (H–V) bias, an ellipticity in the contact hole pattern and, eventually, a patterning limit and critical dimension (CD) nonuniformity. Reducing the absorber thickness is the most effective method to minimize the mask shadowing effect, but this can deteriorate the mask image contrast. In
This work depicts the recent progress towards utilizing several methods to grow Li7La3Zr2O12 (LLZO) thin film electrolytes of Li-rechargeable batteries. The composition, crystalline phase, and Li-ion conductivity of the electrolyte are affected by the pre and post synthesis processing and synthesis method. The properties of the target material used to deposit SSE thin films also affect the nature of electrolyte. Thus, this review article depicts the synthesis of bulk SSE and the various depositi
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