Yonsei University · Materials Science
Professor Keonwook Kang's research lab specializes in computational and atomistic materials science, focusing on the mechanical behavior and defect engineering of advanced nanomaterials. Key research directions include dislocation dynamics and plasticity in crystalline materials, interfacial structure and stability in heterostructured composites, and the design of functional nano-heterostructures for energy and electronic applications. The lab employs advanced simulation techniques such as molecular dynamics, density functional theory, and dislocation-based modeling to understand and predict material properties at the atomic scale.
Figures are computed from collected data and may differ slightly.
Fracture of silicon and germanium nanowires in tension at room temperature is studied by molecular dynamics simulations using several interatomic potential models. While some potentials predict brittle fracture initiated by crack nucleation from the surface, most potentials predict ductile fracture initiated by dislocation nucleation and slip. A simple parameter based on the ratio between the ideal tensile strength and the ideal shear strength is found to correlate very well with the observed br
Dislocation mobility is a fundamental material property that controls strength and ductility of crystals. An important measure of dislocation mobility is its Peierls stress, i.e., the minimal stress required to move a dislocation at zero temperature. Here we report that, in the body-centered cubic metal tantalum, the Peierls stress as a function of dislocation orientation exhibits fine structure with several singular orientations of high Peierls stress-stress spikes-surrounded by vicinal plateau
It has recently been shown that under severe plastic deformation processing bi-metal fcc/bcc composites develop a mechanically stable heterophase interface that joins the {112}fcc//{112}bcc planes in the Kurdjumov-Sachs orientation relationship. In this article, we study variations in the relaxed equilibrium atomic structure of this interface with changes in fcc stacking fault energy (SFE) and lattice mismatch between the two crystals. Using molecular statics/dynamics simulations for three fcc/b
In this article, we describe a method for quantifying the dislocation distribution in incoherent faceted fcc/bcc interfaces, including details such as the facet length and crystallography and the location, Burgers vector, and line orientation of each interface dislocation. The method is applied to a variety of relaxed equilibrium interface structures obtained from atomistic simulations. The results show that minimum energy forms of faceted interfaces are achieved when the serrated interface plan
Abstract The inferior electrical conductivity of conventional electrodes and their slow charge transport impose limitations on the electrochemical performance of supercapacitors (SCs) using those electrodes, necessitating strategies to overcome the limitations. An in situ Ag ion‐incorporated cation‐exchanged bimetallic sulfide/metal oxide heterostructure (Ag‐Co 9‐x Fe x S 8 @α‐Fe x O y ) is synthesized using a two‐step hydrothermal method. The coordination bond formation and Ag nanoparticle (NP)
Abstract Doping of van der Waals layered semiconductor materials is an essential technique to realize their full potential for implementation in nanoelectronics. Herein, defect‐engineered and area‐selective n‐doping of ambipolar multi‐layer WSe 2 are demonstrated via Ar plasma treatment. The contact regions of the WSe 2 are exposed to a mild Ar plasma treatment to induce Se vacancy, while the channel region is protected by a hexagonal boron nitride. The results are systematically analyzed using
Many stimulus‐induced release systems have been studied for the smart control of drug delivery. Mechanical strain is rarely investigated as means of stimulation for these systems, despite the fact that there are many biological processes and human body motions that involve strain changes. In this study, a design for a stretchable reservoir‐based patch‐type release system is suggested. The reservoir made of an elastomer undergoes a decrease in volume when the system is deformed by bending and str
Two-dimensional layered materials have attracted attention for optoelectronic applications owing to their remarkable photonic properties. Here, we report a homojunction device fabricated using n-type ReS2 flakes; the device exhibits p–n diode characteristics. The band structures of 1–5 L ReS2 are theoretically calculated, and the insensitivity of work function to the thickness is experimentally investigated using Kelvin probe force microscopy. The contact resistance and intrinsic mobility of ReS
As semiconductor devices have become miniaturized and highly integrated, interconnection problems such as RC delays, power dissipation, and crosstalk appear. To alleviate these problems, materials with a low dielectric constant should be used for the interlayer dielectric in nanoscale semiconductor devices. Silica aerogel as a porous structure composed of silica and air can be used as the interlayer dielectric material to achieve a very low dielectric constant. However, the problem of its low st
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