Hong-yeol Ju
Yonsei University
研究室紹介
Professor Hong-yeol Ju's research lab specializes in the development and characterization of transparent and oxide-based semiconducting materials, with a focus on thin-film transistors (TTFTs) and metal-insulator transition (MIT) phenomena in vanadium dioxide (VO2) films. The lab explores compositional engineering of complex oxide semiconductors such as a-IGZO and In-Ga-Sn-O (IGSO) to optimize electronic properties like mobility, on/off ratio, and threshold voltage. Additionally, the lab investigates the temperature-dependent optical and electrical behaviors of p-type transparent oxides like CuAlO2 and the dynamic electrical responses during current-induced MIT in VO2 films, aiming to advance applications in transparent electronics and smart devices.
Research Overview
Research Output Trend
Figures are computed from collected data and may differ slightly.
Selected Papers
7Transparent thin-film transistors (TTFTs) with amorphous InGaZnO (a-IGZO) channels have ben prepared by using a combinatorial thin-film synthesis approach. The In composition ratio, In(%)[= In×10 In+Zn+Ga(%)], of the channel of the TTFTs varied with position from 50% to 85%. This alowed us to study TTFTs characteristics as a function of channel composition. The mobility, the on-off ratio and the threshold voltage of the TTFTs varied from 0.2 cm/V·s to 13 cm/V·s, 3 × 100 to 8 × 107 and -24 to 20
Transparent thin-film transistors (TTFTs) with compositionally-graded In-Ga-Sn-O (IGSO)channels were deposited by using a combinatorial approach. The mobilities, the on-off current ratios, and the threshold voltages of the IGSO TTFTs ranged from 0 to 13 cm2V−1s−1, 1 to 2 × 107, -26 to 12 V, respectively. The optimal channel compositions of the IGSO TTFTs were found to be In0.50Ga0.28Sn0.22O and In0.60Ga0.35−0.32Sn0.05−0.08O. The TTFTs with In0.50Ga0.28Sn0.22O channels showed a mobility as high a
The temperature-dependent behavior of p-type transparent semiconducting oxide CuAlO2 singlecrystals prepared by using a flux self-removal method in alumina crucibles was investigated throughtransmittance and photoluminescence (PL) measurements at temperatures from 12 K to roomtemperature. The low-temperature (12 K) PL spectrum shows two weak, broad emission peaks,one at 3.52 eV and the other at 3.08 eV, which we assign to excitonic emission and to defectrelatedemission originating from copper va
The I-V characteristics of two terminal planar VO2 film devices are investigated as the devices undergo the current induced metal insulator transition (I-MIT). The I-MIT occured when the device resistivity reached ~7 Ucm, where metallic grains formed initial conductive current path within insulating matrix. The transition time needed for the I-MIT increased with increasing external resistance, REXT, connected to the device in series, i.e. ~390 ms (REXT ¼ 5 kU) to ~1400 ms (REXT ¼ 20 kU). The tra
We have investigated the effect of over oxidized surface layer on the characteristics of metal-insulator transition (MIT) of vanadium dioxide (VO2) films grown by thermal oxidation method. During the oxidation, the over-oxidized V6O13 layer was formed, which increased contact resistance and thus reduced the resistivity ratio before and after MIT. The contact resistivity of the VO2 film with overoxidized surface layer was in the range 4.2 102 ~ 9.4 104 Ucm2. Interestingly, the over-oxidized sur