Kyung Hee University · Materials Science
Professor Seong Jun Kang's research lab specializes in advanced oxide semiconductors and 2D materials for next-generation optoelectronic and neuromorphic devices. The lab focuses on developing transparent and flexible electronics, including high-performance phototransistors, transparent conductive electrodes, and optoelectronic logic circuits. Key research directions include enhancing device performance through surface engineering, heterostructure design, and defect control in wide-bandgap semiconductors like ZnO and TiO₂, with applications in wearable electronics, robotics, and autonomous systems.
Figures are computed from collected data and may differ slightly.
We developed means to form multilayer superstructures of large collections of single-walled carbon nanotubes (SWNTs) configured in horizontally aligned arrays, random networks, and complex geometries of arrays and networks on a wide range of substrates. The approach involves guided growth of SWNTs on crystalline and amorphous substrates followed by sequential, multiple step transfer of the resulting collections of tubes to target substrates, such as high-k thin dielectrics on silicon wafers, tra
We report the use of graphene as a highly transparent conductive film in liquid-crystal displays (LCDs). Graphene films were synthesised via chemical vapour deposition, transferred onto glass substrates, and then used to fabricate typical twisted nematic LCD cells. LCD cells using graphene as transparent electrodes exhibited optical transmittances 7.7% higher than LCD cells fabricated using conventional conducting layers based on indium tin oxide (ITO) films. The device characteristics of LCD ce
We developed a method to reduce the persistent photoconductivity (PPC) effect of zinc oxide (ZnO) thin film transistors (TFTs) by sequential surface treatment, which includes preannealing/ultraviolet ozone/postannealing (PUP) treatments. Preannealing treatment improves the surface uniformity of the film and eliminates the residual solvent and contaminant molecules without affecting the zinc–oxygen bonds. The ultraviolet ozone (UVO) treatment reduces the oxygen vacancy and increases the amount of
Visible-light phototransistors have been fabricated based on the heterojunction of zinc oxide (ZnO) and titanium oxide (TiO<sub>2</sub>). A thin layer of TiO<sub>2</sub> was deposited onto the spin-coated ZnO film <i>via</i> atomic layer deposition (ALD). The electrical characteristics of the TiO<sub>2</sub> layer were optimized by controlling the purge time of titanium isopropoxide (TTIP). The optimized TiO<sub>2</sub> layer could absorb the visible-light from the sub-gap states near the conduc
Abstract Optoelectronic neuromorphic devices based on oxide semiconductors have been potentially investigated to mimic the functions of human visual synapses. However, the challenge comes from the wide bandgap characteristics of numerous oxide semiconductors, which restricts the response range of the device under ultra‐violet (UV) region. Strategies for widening the response range are mostly focused on artificially generating the defect states, however, most of them results in mimicking the tetr
Highly transparent optical logic circuits operated with visible light signals are fabricated using phototransistors with a heterostructure comprised of an oxide semiconductor (ZnO) with a wide bandgap and quantum dots (CdSe/ZnS QDs) with a small bandgap. ZnO serves as a highly transparent active channel, while the QDs absorb visible light and generate photoexcited charge carriers. The induced charge carriers can then be injected into the ZnO conduction band from the QD conduction band, which ena
The effect of octadecyltrichlorosilane (OTS) treatment on the electronic properties of organic thin-film transistors is investigated using soft x-ray absorption and emission spectroscopy. Analysis of Carbon Kα x-ray emission spectra reveals that treating the SiO2 layer with OTS prior to pentacene deposition increases the number of π-bonding states in the active pentacene layer, which is strongly correlated with the conduction of charge carriers. The role of the increased π-bonding states is veri
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