김기석 교수

Emergent phenomena driven by electronic reconstructions in oxide heterostructures have been intensively discussed. However, the role of these phenomena in shaping the electronic properties in van der Waals heterointerfaces has hitherto not been established. By reducing the material thickness and forming a heterointerface, we find two types of charge-ordering transitions in monolayer VSe₂ on graphene substrates. Angle-resolved photoemission spectroscopy (ARPES) uncovers that Fermi-surf

The backstepping control method provides useful control logic, especially for a cascaded system. Because spacecraft dynamics and kinematics form a cascaded system, the spacecraft slew maneuver problem can be solved using the backstepping control method. However, the simple linear backstepping controller may result in poor design: sluggish motion, trivial nonlinear term cancellation, and excessive control input. To overcome these defects, an effective backstepping control method using a nonlinear

Weyl metal is regarded as a platform toward interacting topological states of matter, where its topological structure gives rise to anomalous transport phenomena, referred to as chiral magnetic effect and ``negative'' magnetoresistivity, the origin of which is chiral anomaly. Recently, the negative magnetoresistivity has been observed with the signature of weak antilocalization at $x=3--4%$ in ${\mathrm{Bi}}_{1\ensuremath{-}x}$${\mathrm{Sb}}_{x}$, where a magnetic field is applied in parallel wi

Abstract Position‐configurable, vertical, single‐crystalline ZnO nanorod arrays are fabricated via a polymer‐templated hydrothermal growth method at a low temperature of 93 °C. A sol‐gel processed dense c ‐oriented ZnO seed layer film is employed to grow nanorods along the c ‐axis direction [0001] regardless of any substrate crystal mismatches. Here, one‐beam laser‐interference lithography is utilized to fabricate nanoscale holes over an entire 2‐in. wafer during the preparation of the polymer t

A reconfigurable flight control system provides better survivability through the automatic reconfiguration of control system when faults occur during flight. The adaptive control method has been effectively applied to the reconfigurable flight control system design. However, reconfigurable flight control systems based on the indirect adaptive control method require persistent input excitation and smooth input-output data. To deal with the persistent input excitation problem and to obtain smooth

Among the layered transition metal dichalcogenides (TMDs) that can form stable two-dimensional crystal structures, molybdenum disulfide (MoS 2 ) has been intensively investigated because of its unique properties in various electronic and optoelectronic applications with different band gap energies from 1.29 to 1.9 eV as the number of layers decreases. To control the MoS 2 layers, atomic layer etching (ALE) (which is a cyclic etching consisting of a radical-adsorption step such as Cl adsorption a

Abstract The recent reports of various photodetectors based on molybdenum disulfide (MoS 2 ) field effect transistors showed that it was difficult to obtain optoelectronic performances in the broad detection range [visible–infrared (IR)] applicable to various fields. Here, by forming a mono-/multi-layer nano-bridge multi-heterojunction structure (more than > 300 junctions with 25 nm intervals) through the selective layer control of multi-layer MoS 2 , a photodetector with ultrasensitive optoe

A periodically aligned submicron ZnO hemispheres array was embedded into a TiO2 nanoparticulate thin film (thickness; ca. 12 μm) as a photoanode for dye-sensitized solar cells (DSSCs). The ZnO hemisphere array provided light scattering centers that excited more dyes and direct electron pathways to the electrodes, which is beneficial for high efficiency DSSCs. Detailed facts of importance to specialist readers are published as ”Supporting Information”. Such documents are peer-reviewed, but not co

Abstract The improvement of the light extraction efficiency (LEE) of a conventional InGaN blue light‐emitting diode (LED) by the incorporation of one‐dimensional ZnO sub‐microrods is reported. The LEE is improved by 31% through the wave‐guiding effect of ZnO sub‐microrods compared to LEDs without the sub‐microrods. Different types of ZnO microrods/sub‐microrods are produced using a simple non‐catalytic wet chemical growth method at a low temperature (90 °C) on an indium‐tin‐oxide (ITO) top conta