Yonsei University · Engineering
Professor Kimoon Lee's research lab specializes in the development and characterization of oxide-based thin-film transistors (TFTs), with a focus on ZnO and other wide-bandgap semiconductors for flexible and transparent electronics. The lab pioneers advanced electrical and optical techniques—such as photo-excited charge-collection spectroscopy and work function engineering using polymer/high-k dielectrics—to directly probe and quantify interfacial trap states and electronic properties at the nanoscale. Key research directions include dielectric engineering for low-voltage operation, atomic doping in two-dimensional materials, and the integration of ZnO-TFTs into functional logic circuits like inverters. The lab emphasizes both fundamental understanding of charge transport and interface physics and practical device applications in next-generation optoelectronics and energy-efficient electronics.
Figures are computed from collected data and may differ slightly.
A History of the Korean Language is the first book on the subject ever published in English. It traces the origin, formation, and various historical stages through which the language has passed, from Old Korean through to the present day. Each chapter begins with an account of the historical and cultural background. A comprehensive list of the literature of each period is then provided and the textual record described, along with the script or scripts used to write it. Finally, each stage of the
Direct quantitative mapping of the density-of-states, named the photo-excited charge-collection technique, for the interface traps at the n-ZnO and/or p-pentacene thin-film transistor channel is implemented by using monochromatic photons which are carried by optical fibers and are probed onto thin-film transistors.
The authors report on the fabrication of a low-voltage-driven top-gate ZnO thin-film transistor with a polymer/high-k oxide double-layer dielectric. Hybrid double-layer dielectric (k=∼9.8) was formed on patterned ZnO through sequential deposition processes: spin casting of 45-nm-thin poly-4-vinylphenol and e-beam evaporation of 50-nm-thick amorphous high-k oxide (CeO2–SiO2 mixture). Room-temperature-deposited ZnO channel exhibits much rougher surfaces compared to that of 100°C deposited ZnO, so
We report on the fabrication and application of top-gate ZnO thin-film transistors (TFTs) with a poly-4-vinylphenol (PVP) gate dielectric layer formed on n-ZnO by spin casting. Al, Au, and NiOx top-gate metals patterned on the PVP of a top-gate TFT by thermal evaporation exhibited different threshold voltages (Vt) and saturation currents. This provides us with an all-electrical way to measure the work function of an unknown new electrode (NiOx) based on those of two reference electrodes (Al and
We report on photo-excited trap-charge-collection spectroscopy, contrived to measure the density of deep-level traps near channel/dielectric interface in a working ZnO based thin-film transistor as a function of photon probe energy. Free charges trapped at a certain energy level are liberated by the correspondingly energetic photons and then electrically collected at the source/drain electrodes. During this photo-electric process, the threshold voltage of TFT shifts and its magnitude provides th
Discoveries of two-dimensional (2D) magnetism originated from confined atomic layers in van der Waals (vdW) crystals provide an interesting arena for elucidating its fundamentals and enrich magneto-electric and quantum properties. However, a material that exhibits intrinsic 2D magnetism of interstitial electrons occupying layered space, as a root system of magnetic vdW crystals, remains obscure. In this work, 2D ferromagnetic vdW electride, [RECl]2+·2e− (RE = Y and La) is reported with perfectly
Abstract Substitutional atomic doping is one of the most convenient and precise routes to modulate semiconducting material properties. Although two‐dimensional (2D) layered transition metal dichalcogenides (TMDs) are of great interest as a prominent semiconducting material due to their unique physical/chemical properties, such a practical atomic doping is still rare, possibly due to the intrinsic localization nature of conduction paths based on d‐band states. Here, using single‐crystalline Cl‐do
We report on the fabrication of ZnO-based depletion-load-type inverter composed of two n-channel ZnO thin-film transistors (TFTs) with a low-k poly-4-vinylphenol and high-k poly(vinylidene fluoride-trifluoroethylene) double polymer dielectric. One of the two ZnO channels in the inverter was illuminated by 352 nm wavelength ultraviolet so that the illuminated ZnO channel might be depleted. That ZnO-TFT plays as a driver transistor in the inverter set where the original TFT is used as a load one.
We report the origin of improved hole conduction without band-gap collapse in Cu-doped NiO.
Improved dynamic properties of ZnO-based photo-transistor with polymer gate dielectric by ultraviolet treatment, Lee, Kimoon, Kim, Ki-tae, Choi, Jeong-M, Oh, Min Suk, Hwang, D K, Jang, Sungjin, Kim, Eugene, Im, Seongil
Interlayer coupling between individual unit layers is known to be critical in manipulating the layer-dependent properties of two-dimensional (2D) materials. While recent studies have revealed that several 2D materials with significant degrees of interlayer interaction (such as black phosphorus) show strongly layer-dependent properties, the origin based on the electronic structure is drawing intensive attention along with 2D materials exploration. Here, the direct observation of a highly dispersi
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