Sungkyunkwan University · Materials Science
Professor Se-Young Jeong's research lab specializes in advanced functional materials, with a focus on oxide semiconductors, 2D materials, and high-conductivity metals. The lab investigates the magnetic and electronic properties of doped ZnO systems, particularly the origins of ferromagnetism in transition-metal-doped oxides, and explores the synthesis and characterization of high-quality graphene heterostructures. A key research direction involves enhancing electrical conductivity in single-crystalline copper through high-pressure annealing, aiming to improve performance in next-generation electronic devices. The lab combines advanced characterization techniques such as neutron and X-ray diffraction with theoretical modeling to understand defect-mediated phenomena and interface engineering in functional oxides and 2D materials.
Figures are computed from collected data and may differ slightly.
Oxidation can deteriorate the properties of copper that are critical for its use, particularly in the semiconductor industry and electro-optics applications<sup>1-7</sup>. This has prompted numerous studies exploring copper oxidation and possible passivation strategies<sup>8</sup>. In situ observations have, for example, shown that oxidation involves stepped surfaces: Cu<sub>2</sub>O growth occurs on flat surfaces as a result of Cu adatoms detaching from steps and diffusing across terraces<sup>9
Abstract The ferromagnetism of ZnO‐based magnetic semiconductors has been investigated by theoretical calculation and many kinds of experiments. In the Cu‐doped ZnO system, ferromagnetic ordering by Cu magnetic moments does not exist, but Cu‐doped ZnO can have ferromagnetism due to the distortion of the ZnO‐based structure by Cu doping. In this study, we investigated the magnetic properties of Cu‐doped ZnO and discussed the possible origin of magnetism in this system. (© 2004 WILEY‐VCH Verlag Gm
The scientific community has attempted to fabricate superconductors that work at room temperature; however, this goal has not yet been achieved. Considering miniaturization of devices and the requirement of low-power consumption in electronics, it is important to enhance room-temperature conductivity. We prepared the best conductor using crystallization and enhanced its conduction using high-pressure annealing. Single-crystal copper showed a conductivity enhancement of 12–14% after treatment und
Abstract We report on a study of magnetic cluster in Co‐doped ZnO using neutron diffraction. The samples are fabricated by the sol–gel process and the structural properties are characterized by X‐ray diffraction and neutron diffraction. The diffraction data obtained by neutron are compared with the results of X‐ray diffraction and refined by the Rietveld refinement method. The secondary phases are detected by neutron diffraction in above 5 mol% Co‐doping of ZnO samples and the fractions of the p
Abstract Large single crystals of orthorhombic K 2 ZnCl 4 with optical quality have been grown by the Czochralski method. The elastic constants and their temperature and pressure derivatives have been determined from ultrasonic resonance frequencies of thick plates of different orientation and the shift of these frequencies induced by temperature and pressure changes, respectively. K 2 ZnCl 4 shows a small elastic anisotropy. Measurement of the dielectric constant was made along the ferroelectri
Ultrasmooth single-crystalline metallic thin films provide several key advantages for the fabrication of well-defined and high-resolution plasmonic nanostructures, particularly complex integrated nanocircuits. For this purpose, copper is generally regarded as a poor plasmonic material compared to gold and silver because of its notorious oxidation issues when subjected to air exposure. Here, we report on the use of large-area grain-boundary-free copper films grown epitaxially on sapphire substrat
The electrical transport characteristics and anomalous Hall effect (AHE) were investigated for a hydrogen-injected Co-doped ZnO thin film. Based on the measurements of resistivity and the Hall effect between 5 K and 300 K, the existence of Co-H-Co complexes was observed to introduce the AHE and enable the AHE to persist up to room temperature. The observed H-induced AHE originates from the asymmetric scattering of carrier hopping between the localized states driven by ferromagnetic Co-H-Co compl
Realizing laterally continuous, ultraflat silver (Ag) single-crystal films is a significant technological challenge. Ag thin film grown on various hetero-substrates has been used in numerous applications, due to its superior electrical and optical properties. To exploit these properties without degradation and apply these films to high-precision patterning, surface plasmonics, and so on, a high-quality thin film having an ultraflat surface and few grain boundaries is needed. A zinc oxide (ZnO) b
${\mathrm{Pb}}_{3}$(${\mathrm{PO}}_{4}$${)}_{2}$ has two types of domain walls, the W wall and the W' wall. However, both types of domain walls in ${\mathrm{Pb}}_{3}$(${\mathrm{PO}}_{4}$${)}_{2}$ belong to the W wall, because they both can be represented as crystallographically prominent planes of fixed indices. We will call them the ${\mathit{W}}_{\mathit{m}}$ wall and the ${\mathit{W}}_{\mathit{b}}$ wall instead of the W wall and the W' wall, respectively. The z axis of the prototypic phase is
Abstract Temperature and pressure derivatives of the elastic constants, indices of refraction, dielectric constants, Faraday effect and thermal expansion of RbMnCl 3 near T c = 278 K confirm the existence of a second‐order phase transition. A strongly anomalous behaviour is observed with the elastic shear stiffness c 44 which possesses a positive temperature derivative and a negative pressure derivative. These properties and also the pressure derivative of the transition temperature, dT c / dp =
Copper surfaces that exhibit a wide range of achromatic colors while still metallic have not been studied, despite advancements in antireflection coatings. A series of achromatic copper films grown with [111] preferred orientation by depositing 3D porous nanostructures is introduced via coherent/incoherent atomic sputtering epitaxy. The porous copper nanostructures self-regulate the giant oxidation resistance by constructing a curved surface that generates a series of monoatomic steps, followed
Electron beam irradiation can be used to remove shallow donor type hydrogen located in Zn(Co)–O bonding centers in Co-doped ZnO, which enables to modify the conduction band and the magneto-transport characteristics of Co-doped ZnO.
In 2D noble metals like copper, the carrier scattering at grain boundaries has obscured the intrinsic nature of electronic transport. However, it is demonstrated that the intrinsic nature of transport by hole carriers in 2D copper can be revealed by growing thin films without grain boundaries. As even a slight deviation from the twin boundary is perceived as grain boundaries by electrons, it is only through the thorough elimination of grain boundaries that the hidden hole-like attribute of 2D si
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