Publications by authors named "Won Ja Min"

This study aims to develop a reference material that enables precise management of dopant distribution in power semiconductors. We thoroughly investigate the structural and surface properties of 4H-silicon carbide (4H-SiC) single crystals implanted without annealing using aluminum (Al) and phosphorus (P) ions. Ion-implanted 4H-SiC was thoroughly evaluated using advanced techniques, including X-ray diffraction (XRD), field emission transmission electron microscopy (FE-TEM), atomic force microscopy (AFM), time of flight medium energy ion scattering (ToF-MEIS), and secondary ion mass spectrometry (SIMS).

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Article Synopsis
  • Core/shell quantum dots (QDs), particularly CdSe/ZnS, display varying optical properties due to differences in their interfacial structures, which are influenced by the synthetic methods used.
  • This study utilized time-of-flight medium energy ion-scattering spectroscopy (TOF-MEIS) to analyze the QDs, revealing the presence of an alloyed layer at the CdSe/ZnS interface.
  • The research concluded that this interfacial alloying occurs because CdSe seeds dissolve during synthesis, and the type of ligand in the solvent affects the interface shape.
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We have developed a methodology that analyzes the dimensions and conformal doping profiles in fin field effect transistors (FinFET) using time-of-flight medium energy ion scattering (TOF-MEIS). The structure of a 3D FinFET and As dopant profiles were determined by comprehensive simulations of TOF-MEIS measurements made in three different scattering geometries. The width and height of a FinFET and the As doping profiles in the top, side, and bottom of fin were analyzed simultaneously.

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We report the quantitative compositional profiling of 3-5 nm CdSe/ZnS quantum dots (QDs) conjugated with a perfluorooctanethiol (PFOT) layer using the newly developed time-of-flight (TOF) medium-energy ion scattering (MEIS) spectroscopy with single atomic layer resolution. The collection efficiency of TOF-MEIS is 3 orders of magnitude higher than that of conventional MEIS, enabling the analysis of nanostructured materials with minimized ion beam damage and without ion neutralization problems. The spectra were analyzed using PowerMEIS ion scattering simulation software to allow a wide acceptance angle.

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The metal (M = Cd2+ and Zn2+) complexes with trioctylphosphine chalcogenide (TOPE, E = O, S, and Se) are prepared by electrospray ionization, and their relative stabilities and intramolecular reactions are studied by collision-induced dissociation (CID) with Xe under single collision conditions. These metal-TOPE complexes are considered as molecular precursors for the colloidal synthesis of II-VI compound semiconductor nanocrystals employing TOPO as a metal-coordinating solvent and TOPS or TOPSe as a chalcogen precursor. Of the various [M + nTOPE]2+ (n = 2-7) ions generated by ESI, the n = 2-4 complexes are characterized by CID as a function of collision energy.

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