Yonsei University · Materials Science
Professor Seongil Im's research lab specializes in the development and characterization of two-dimensional (2D) semiconductor devices and transparent/ferroelectric thin-film transistors for next-generation optoelectronic and memory applications. The lab focuses on innovative device architectures using materials such as ZnO, MoS2, and transition metal dichalcogenides, emphasizing defect engineering, interface control, and novel fabrication techniques like direct imprinting. Key research directions include high-performance transparent and nonvolatile memory devices, with a strong emphasis on material integration, contact engineering, and scalable fabrication methods for flexible and transparent electronics.
Figures are computed from collected data and may differ slightly.
Transparent ZnO thin-film transistors (TFTs) with a defect-controlled channel and channel/dielectric interface maintain good photo-stability during device operation. The figure shows a cross-sectional view of a top-gate ZnO-based transparent TFT/storage capacitor cell structure, connected to front-panel organic-light-emitting-diode pixels to operate in bottom emission mode.
Nonvolatile memory ferroelectric thin-film transistors (FeTFT) with P(VDF-TrFE) polymer are demonstrated with both n-channel ZnO and p-channel pentacene. A high mobility of ≈1 cm2 V−1 s−1 and large memory window of ≈20 V are achieved through the organic ferroelectric– inorganic channel hybrid device of ZnO-FeTFT. WRITE/ERASE states are clearly distinguished by ±20 V switching for ZnO- and pentacene-FeTFTs.
Two MoS2 field-effect transistors are compared using graphene and Au/Ti source-drain contacts in respects of their Ohmic and OFF behavior on an identical MoS2 nanosheet. As a result, graphene-contact appears not only to show superior ohmic behavior to those of Au/Ti but also more enhanced OFF state behavior. Such results are attributed to the electric-field-induced work function tuning of exfoliated graphene.
Nanosheet transistors based on mechanically exfoliated MoS2 and other transition metal dichalcogenide layers have already been reported demonstrating good device performances. In an approach to synthesize a large area two-dimensional (2D) sheet, chemical vapor deposition methods were reported and the transfer of those sheets onto other arbitrary substrates was also attempted, although studies on the direct imprinting of such 2D semiconductor sheets are rare. Here, we report on a direct imprintin
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