https://scholar.dgist.ac.kr/handle/20.500.11750/1136 2026-04-04T18:35:13Z 2026-04-04T18:35:13Z Jeong, Jaewook Kim, Joonwoo https://scholar.dgist.ac.kr/handle/20.500.11750/10118 2025-07-24T07:31:01Z 2019-06-30T15:00:00Z

Title: Electrical characterization of graphene source/drain electrodes in amorphous indium-gallium-zinc-oxide thin-film transistors subjected to plasma treatment in contact regions Author(s): Jeong, Jaewook; Kim, Joonwoo Abstract: In this paper, the electrical characteristics of a-IGZO TFTs with graphene source/drain (S/D) electrodes subjected to argon plasma treatment are analyzed. Depending on the channel length (L), the a-IGZO TFTs showed parasitic resistance dominant (L < 30 μm) and channel conduction dominant regions (L ≥ 30 μm). Using the transmission line method, the intrinsic parameters were extracted. The intrinsic field-effect mobility was about 9.79 cm2 V-1 s-1 and the width-normalized parasitic resistance value was about 460 Ωcm, which are comparable with those of a-IGZO TFTs having S/D plasma-treated regions with no contact metal. Temperature-dependent measurement indicates that the graphene electrodes affected the thermally deactivated behavior of the a-IGZO TFTs, which is different from the case of a-IGZO TFTs having conventional metal electrodes. © 2019 The Japan Society of Applied Physics.

2019-06-30T15:00:00Z Jo, Jeong-Wan Kim, Kyung-Tae Park, Ho-Hyun Park, Sung Kyu Heo, Jae Sang Kim, Insoo Lee, Myoung-Jae https://scholar.dgist.ac.kr/handle/20.500.11750/9989 2025-07-24T07:30:25Z 2019-05-31T15:00:00Z

Title: High-Speed and Low-Temperature Atmospheric Photo-Annealing of Large-Area Solution-Processed IGZO Thin-Film Transistors by Using Programmable Pulsed Operation of Xenon Flash Lamp Author(s): Jo, Jeong-Wan; Kim, Kyung-Tae; Park, Ho-Hyun; Park, Sung Kyu; Heo, Jae Sang; Kim, Insoo; Lee, Myoung-Jae Abstract: An efficient photo-annealing approach for high-performance solution-processed metal-oxide thin film transistors (TFTs) was demonstrated by using programmable pulse operation of xenon flash lamp. The flash lamp annealing (FLA) process could offer not only low-temperature (≈100° C) processing but also ultra-fast annealing speed of the order of seconds under air ambient conditions. Solution-processed amorphous indium-gallium-zinc-oxide (α-IGZO) TFTs implemented by the FLA process typically exhibited much improved electrical performance such as saturation mobility of >10.8 cm2V−11s−1, ION/IOPP of >108, and subthreshold slope of as steep as 0.24 V/dec. X-ray photoelectron spectroscopy analysis of a-IGZO films indicates that the FLA can provide sufficient activation energy for rapid formation of solid a-IGZO bonds within 30 s. The high-quality metal-oxide films achieved by an atmospheric and low temperature FLA method may represent a significant advance for scalable fabrication of flexible and printed metal-oxide electronics. © 2019, The Korean Physical Society.

2019-05-31T15:00:00Z Oh, Jae Taek Bae, Sung Yong Ha, Su Ryong Cho, Hongjoo Lim, Sung Jun Boukhvalov, Dana W. Kim, Younghoon Choi, Hyosung https://scholar.dgist.ac.kr/handle/20.500.11750/9912 2025-07-24T07:32:14Z 2019-04-30T15:00:00Z

Title: Water-resistant AgBiS 2 colloidal nanocrystal solids for eco-friendly thin film photovoltaics Author(s): Oh, Jae Taek; Bae, Sung Yong; Ha, Su Ryong; Cho, Hongjoo; Lim, Sung Jun; Boukhvalov, Dana W.; Kim, Younghoon; Choi, Hyosung Abstract: Lead-free, water-resistant photovoltaic absorbers are of significant interest for use in environment-friendly and water-stable thin film solar cells. However, there are no reports on the water-resistance characteristics of such photoactive materials. Here, we demonstrate that silver bismuth sulfide (AgBiS 2 ) nanocrystal solids exhibit inherent water resistance and can be employed as effective photovoltaic absorbers in all-solid-state thin film solar cells that show outstanding air and moisture stabilities under ambient conditions. The results of X-ray photon spectroscopy (XPS) and X-ray diffraction (XRD) analyses show that there is no change in the chemical composition and crystal structure of the AgBiS 2 nanocrystal solids after a water treatment. Based on these results, AgBiS 2 nanocrystal solar cells are fabricated. These devices also do not show any drop in performance after a water treatment, confirming that the AgBiS 2 nanocrystal solids are indeed highly water-resistant. In contrast, lead sulfide (PbS) colloidal quantum dot (CQD) solar cells show significant decrease in performance after a similar water treatment. Using XPS analysis and density functional theory (DFT) calculations, we confirm that the iodine removal and the surface hydroxylation of the water-treated PbS CQD solids are the primary reasons for the observed decrease in the device performance of the CQD solar cells. © 2019 The Royal Society of Chemistry.

2019-04-30T15:00:00Z Hyun, Cheol-Min Choi, Jeong-Hun Lee, Seung Won Seo, Seung-Young Lee, Myoung-Jae Kwon, Se-Hun Ahn, Ji-Hoon https://scholar.dgist.ac.kr/handle/20.500.11750/9749 2025-07-24T07:32:14Z 2019-03-31T15:00:00Z

Title: Synthesis of Bi2Te3 Single Crystals with Lateral Size up to Tens of Micrometers by Vapor Transport and Its Potential for Thermoelectric Applications Author(s): Hyun, Cheol-Min; Choi, Jeong-Hun; Lee, Seung Won; Seo, Seung-Young; Lee, Myoung-Jae; Kwon, Se-Hun; Ahn, Ji-Hoon Abstract: Bismuth telluride (Bi 2 Te 3 ) has recently attracted significant attention owing to its unique physical properties as a three-dimensional topological insulator and excellent properties as a thermoelectric material. Meanwhile, it is important to develop a synthesis process yielding high-quality single crystals over a large area to study the inherent physical properties and device applications of two-dimensional materials. However, the maturity of Bi 2 Te 3 vapor-phase synthesis is not good, compared to those of other semiconductor two-dimensional crystals. In this study, therefore, we report the synthesis of relatively large-area Bi 2 Te 3 crystals by vapor transport method, and we investigated the key process parameters for a synthesis of relatively thin and large-area Bi 2 Te 3 crystals. The most important factor determining the crystal synthesis was the temperature of the substrate. A Bi 2 Te 3 device exhibited a considerable photocurrent when the laser was irradiated inside the electrode area. This indicated that the photo-thermoelectric effect was the main mechanism of generation of photocurrent. The estimated Seebeck coefficient of the device was ∼196 μV/K, which is comparable to the previously reported high Seebeck coefficient of Bi 2 Te 3 . This synthesis method can guide the development and applications of various types of layered crystals with the space group of R3̄m. © Copyright 2019 American Chemical Society.

2019-03-31T15:00:00Z