Article
Chemistry, Physical
Ki Chang Kwon, Tae Hyung Lee, Seokhoon Choi, Kyoung Soon Choi, Seung O. Gim, Sa-Rang Bae, Jong-Lam Lee, Ho Won Jang, Soo Young Kim
Summary: This study presents a simple method for synthesizing alloyed transition metal disulfides (TMD) thin films and their application as hole transport layers in OLEDs. The physical and chemical properties of the alloyed TMD layers can be controlled by varying precursor concentrations. The device performance of OLEDs based on alloyed TMD layers is comparable to conventional PEDOT:PSS, and device stability in air is significantly improved.
APPLIED SURFACE SCIENCE
(2021)
Article
Chemistry, Multidisciplinary
Geun Woo Baek, Seung Gi Seo, Donghyo Hahm, Yeon Jun Kim, Kyunghwan Kim, Taesoo Lee, Jaeyoul Kim, Wan Ki Bae, Sung Hun Jin, Jeonghun Kwak
Summary: In this study, efficient and stable AM-QLEDs for next-generation displays are demonstrated by comparing different configurations of QLEDs and TFTs. A 5x5 AM-QLED display array controlled using SWNT TFTs is successfully demonstrated, contributing to the development of advanced AM-QLED displays.
ADVANCED MATERIALS
(2023)
Article
Chemistry, Multidisciplinary
Volodymyr B. Koman, Xun Gong, Naveed A. Bakh, Kevin Silmore, Daniel P. Salem, Tedrick Thomas Salim Lew, Matthias Kuehne, Daichi Kozawa, Minkyung Park, Michael S. Strano
Summary: This study develops a novel sensing platform using MoS2 monolayers as 2D sensing interfaces to assess molecular transport through cell layers with subcellular spatial resolution. The technique allows spatial imaging of molecular permeability and detection of nanoscale cellular junctions.
ADVANCED FUNCTIONAL MATERIALS
(2022)
Article
Materials Science, Multidisciplinary
Tara Pena, Shoieb A. Chowdhury, Ahmad Azizimanesh, Arfan Sewaket, Hesam Askari, Stephen M. Wu
Summary: A method to induce tensile and compressive strain into two-dimensional transition metal dichalcogenide (TMDC) MoS2 via deposition of stressed thin films is demonstrated, allowing for direct engineering of strain magnitude on a flake-to-flake level. Optically transparent stressors are chosen to probe MoS2 strain through Raman spectroscopy, showing layer-by-layer strain transfer. By using thin films with higher stress, strain can be engineered to be even higher, with negligible defects induced into MoS2 when thermal evaporation is used.
Article
Materials Science, Multidisciplinary
Thi Thu Thuy Can, Young-Jin Kwack, Woon-Seop Choi
Summary: In this study, fine MoS2 patterns were successfully fabricated using electrohydrodynamic (EHD)-jet printing technology for the first time with highly uniform coverage. These patterns were applied in thin-film transistors (TFTs) and exhibited good electrical performance.
MATERIALS & DESIGN
(2021)
Review
Chemistry, Multidisciplinary
Paramaguru Ganesan, Hoi Nok Tsao, Peng Gao
Summary: Organic light-emitting transistors (OLETs) combine the switching functionality of field-effect transistors (FETs) with the light-emitting characteristics of organic light-emitting diodes (OLEDs) to simplify device architecture for flat panel and flexible display technology. Key tactics include improving electrode design, utilizing vertical architecture for short channel lengths and high aperture ratios, and incorporating high–k dielectric materials to enhance device performance.
ADVANCED FUNCTIONAL MATERIALS
(2021)
Article
Physics, Applied
Hattan Abuzaid, Nicholas X. Williams, Aaron D. Franklin
Summary: Research in semiconducting 2D materials, particularly transition metal dichalcogenides, has shown promising potential in competing with silicon in various application areas. Despite the benefits, 2D materials still face challenges such as poor reliability, performance variability, and limited scalability in fabrication. Continuous research efforts and appropriate benchmarking are crucial for further development of 2D materials in future technologies.
APPLIED PHYSICS LETTERS
(2021)
Article
Engineering, Chemical
Marwin R. Gallardo, Micah Belle Marie Yap Ang, Jeremiah C. Millare, Chi-Lan Li, Hui-An Tsai, Shu-Hsien Huang, Kueir-Rarn Lee
Summary: Functionalized MoS2 nanosheets were synthesized and incorporated into polyamide matrix to develop TFN membranes for dehydration. The TFN membrane with amine-modified MoS2 exhibited the highest separation performance. The membrane showed robust performance under challenging conditions and stable long-term operational performance.
JOURNAL OF MEMBRANE SCIENCE
(2023)
Article
Optics
Longheng Qi, Peian Li, Xu Zhang, Ka Ming Wong, Kei May Lau
Summary: A prototype of full-color micro-LED micro-display with a pixel density of 391 ppi is demonstrated using InGaN/AlGaInP heterogeneous integration. This display shows the feasibility and prospects of high brightness, good color performance, and high-resolution micro-LED micro-displays in future metaverse applications.
LIGHT-SCIENCE & APPLICATIONS
(2023)
Article
Chemistry, Multidisciplinary
Seunghyeon Ji, Sa-Rang Bae, Luhing Hu, Anh Tuan Hoang, Myeong Jin Seol, Juyeong Hong, Ajit Kumar Katiyar, Beom Jin Kim, Duo Xu, Soo Young Kim, Jong-Hyun Ahn
Summary: This study presents a fabrication method for an active-matrix PeLED display, achieved through the heterogeneous integration of perovskite light-emitting diodes with MoS2 TFTs. The display exhibits excellent brightness control capability and high switching speed, showcasing the potential of PeLEDs as candidates for next-generation displays.
ADVANCED MATERIALS
(2023)
Article
Chemistry, Multidisciplinary
Yu-Ming Chang, Ni Yang, Jiacheng Min, Fangyuan Zheng, Chun-Wei Huang, Jui-Yuan Chen, Yuxiang Zhang, Pengfei Yang, Chenyang Li, Hao-Yu Liu, Beilin Ye, Jian-Bin Xu, Han-Yi Chen, Zhengtang Luo, Wen-Wei Wu, Kaimin Shih, Jing-Kai Huang, Lain-Jong Li, Yi Wan
Summary: 2D semiconducting transition metal dichalcogenides (TMDs) are promising candidates for advancing semiconductor technology. This study demonstrates robust and reproducible growth of single-oriented MoS2 on Fe2O3-decorated sapphire, achieving an impressive 99% ratio. Simulations show a preferred 0 degrees alignment on the Fe2O3-(0001) surface, ensuring single-oriented growth even on mirror-reflected surfaces. These findings highlight Fe2O3-decorated sapphires as effective substrates enabling epitaxial control of TMD orientation.
ADVANCED FUNCTIONAL MATERIALS
(2023)
Article
Physics, Applied
Jaewon Kim, Seunghyeon Oh, Hyerin Jo, Hongseok Oh
Summary: We present the fabrication and characterization of indium gallium zinc oxide (IGZO) tunneling thin-film transistors. Radio-frequency magnetron sputtering was used to deposit both the IGZO channel and an Al2O3 tunneling barrier layer. Our device showed rapid saturation at a minimal drain bias compared to a conventional device. Moreover, we observed two distinct current saturation mechanisms within a single device, attributed to the competition between the depletion envelope near the source electrode and channel depletion near the drain electrode. This work provides an industry-friendly method for implementing tunnel-contact approach in the display industry.
APPLIED PHYSICS EXPRESS
(2023)
Article
Engineering, Chemical
Shuxuan Li, Shenju Du, Shaoxiao Liu, Baowei Su, Lihui Han
Summary: In this study, an ultra-thin and ultra-smooth TFN OSN membrane was fabricated using an interfacial polymerization process. The membrane exhibited excellent solvent resistance and fouling resistance.
SEPARATION AND PURIFICATION TECHNOLOGY
(2022)
Article
Engineering, Electrical & Electronic
Yan Xue, Longjie Wang, Yu Zhang, Guangmin Liang, Junwei Chu, Baixiang Han, Weiran Cao, Congwei Liao, Shengdong Zhang
Summary: A 31-inch 4K flexible AMOLED display with GOA technology has been developed to reduce leakage current and achieve high pixel density using IJP OLED process. TG IGZO TFTs are utilized to further improve signal transfer speed in the display.
IEEE ELECTRON DEVICE LETTERS
(2021)
Article
Materials Science, Ceramics
Kumar Kaushlendra, Pradeep Kumar, Diksha Arora, Bhanu Ranjan, Davinder Kaur
Summary: This article presents a Cu/MoS2/NiMnIn memory structure for flexible electronics, and investigates the resistive switching characteristics. Two different devices were fabricated, one without sulfur vacancies and one with sulfur vacancies in the MoS2 thin film. The memory structure showed stable resistive switching behavior, good endurance cycles and data retention capability. Furthermore, the external temperature and magnetic field were found to affect the SET voltage and enhance the data storage capability of the device.
CERAMICS INTERNATIONAL
(2023)
Article
Engineering, Electrical & Electronic
Gyusoup Lee, Jungyeop Oh, Eui Joong Shin, Seongho Kim, Youngkeun Park, Min Ju Kim, Sung-Yool Choi, Byung Jin Cho
Summary: We propose a single device neuron called SD L-FeFET that simulates neuronal dynamics for both excitatory and inhibitory connections while reducing standby power. The spiking neural network (SNN) using SD L-FeFET achieves a pattern recognition accuracy of 92.5% for MNIST handwriting digits and 91.7% for face recognition, comparable to state-of-the-art SNN simulations with conventional complex cell designs.
IEEE ELECTRON DEVICE LETTERS
(2023)
Article
Chemistry, Multidisciplinary
Joon Pyo Kim, Seong Kwang Kim, Seohak Park, Song-hyeon Kuk, Taeyoon Kim, Bong Ho Kim, Seong-Hun Ahn, Yong-Hoon Cho, YeonJoo Jeong, Sung-Yool Choi, Sanghyeon Kim
Summary: The advent of big data has created a need for power-efficient computing beyond the capabilities of the Von Neumann architecture. Inspired by the human brain, neuromorphic computing has the potential to greatly reduce power consumption through matrix multiplication, but current synaptic devices often suffer from limited linearity and symmetry without the use of incremental step pulse programming (ISPP). In this study, we successfully demonstrated a charge-trap flash (CTF)-based synaptic transistor using a trap-level engineered Al2O3/Ta2O5/Al2O3 gate stack for efficient neuromorphic computing. By precisely controlling the conductance with a precision of more than 6 bits, we achieved highly linear and symmetric modulation of conductance using short and low-voltage pulses, resulting in low power consumption and high reliability. Additionally, we achieved high learning accuracy in training 60,000 MNIST images.
Article
Chemistry, Multidisciplinary
Cheolmin Park, Seung Hun Han, Hyeok Jun Jin, Woonggi Hong, Sung-Yool Choi
Summary: In order to solve the image deterioration caused by the pixel miniaturization in high-resolution CMOS image sensor technology, a photodiode with an enhanced mechanism based on a distinctive device structure is needed. This study introduced a photodiode consisting of gold nanoparticles/monolayer graphene/n-type trilayer MoS2/p-type Si bulk, which achieved ultrafast rising/falling times due to the narrow depletion width resulting from the 2D/3D heterojunction. To compensate for the expected low absorbance, plasmonic gold nanoparticles on monolayer graphene were introduced, resulting in broadband enhanced EQE.
Article
Chemistry, Multidisciplinary
Jungyeop Oh, Sungkyu Kim, Changhyeon Lee, Jun-Hwe Cha, Sang Yoon Yang, Sung Gap Im, Cheolmin Park, Byung Chul Jang, Sung-Yool Choi
Summary: With advances in artificial intelligent services, brain-inspired neuromorphic systems with synaptic devices are recently attracting significant interest to solve the von Neumann bottleneck. However, deep neural networks suffer from huge power consumption and vanishing gradient problem. This research proposes a memristor-based compact and energy-efficient neuron device to implement the ReLU activation function, successfully resolving the vanishing gradient problem and achieving high-density and energy-efficient hardware neuromorphic systems.
ADVANCED MATERIALS
(2023)
Article
Engineering, Electrical & Electronic
Yonghee Jeong, Hyunjin Kim, Jungyeop Oh, Sung-Yool Choi, Hamin Park
Summary: This study comprehensively investigates the bias temperature instability of a-IGZO thin-film transistors (TFTs) by analyzing the behavior of transfer characteristics under repeated bias stress and recovery at different temperatures. The results reveal that the correlation between transfer characteristics and stress time depends on temperature, exhibiting opposite trends. This can be explained by the competition between trapped electron and oxygen vacancy mechanisms, with the predominant mechanism determined by temperature.
JOURNAL OF ELECTRONIC MATERIALS
(2023)
Article
Chemistry, Multidisciplinary
Wonbae Ahn, Han Beom Jeong, Jungyeop Oh, Woonggi Hong, Jun-Hwe Cha, Hu Young Jeong, Sung-Yool Choi
Summary: This study proposes a copper migration-controlled electrochemical metallization (ECM) memristor using two-dimensional materials, MoS2 and Al2O3, as the switching medium. The device exhibits low switching voltage, uniform switching, and a wide switching range, with excellent retention characteristics in the long-term reliable neuromorphic system. The contribution of the Al2O3 layer to the retention characteristic is investigated through filament morphology observation and copper migration component analysis.
Article
Engineering, Electrical & Electronic
Juwon Kim, Hyunjin Kim, Jungyeop Oh, Sung-Yool Choi, Hamin Park
Summary: The threshold voltage of a-IGZO TFTs can shift under certain stress conditions, and the direction of the shift depends on the illumination condition. The shift is mainly influenced by ionized oxygen vacancies and trapped electrons.
SOLID-STATE ELECTRONICS
(2023)
Article
Materials Science, Multidisciplinary
Injun Lee, Cheolmin Park, Tae Soo Kim, Minsoo Kang, Hyeongyeol Oh, Jinhyeong Jang, Jungjae Park, Jong Min Yuk, Hohjai Lee, Chan Beum Park, Sung-Yool Choi, Kibum Kang, Wonryung Lee, Byeong-Soo Bae
Summary: Upconversion nanoparticles (UCNPs) are encapsulated with a siloxane polymer (UCNP@SiOx) through a sol-gel process, enabling water stability and photo-patternability. The UCNP@SiOx demonstrates no significant decrease in upconversion photoluminescence (PL) intensities and PL decay time after immersion in water, and is found to be non-toxic. Integration of UCNP@SiOx with MoS2 phototransistors results in enhanced responsivity and specific detectivity, as well as excellent mechanical durability. This work introduces a facile synthesis method for water-stable and photo-patternable siloxane-encapsulated UCNPs and a strategy for fabricating high-performance flexible NIR phototransistors through wavelength conversion.
ADVANCED OPTICAL MATERIALS
(2023)
Article
Nanoscience & Nanotechnology
Cheolmin Park, Gi Woong Shim, Woonggi Hong, Sung-Yool Choi
Summary: In this study, large-area hierarchical transition metal dichalcogenide (TMD) nanostructures were grown vertically on a substrate, showing potential for electrochemical applications due to their high density of edge states. A singular point promoting vertical growth was identified through optical dark-field data and micro-Raman spectroscopy, attributed to the layer-dependent dielectric constant of MoS2. Furthermore, a method for expanding the vertically grown MoS2 region on a substrate was discussed using analytical methods based on hydromechanics.
ACS APPLIED NANO MATERIALS
(2023)
Article
Chemistry, Multidisciplinary
Dong-Ha Kim, Jun-Hwe Cha, Sanggyu Chong, Su-Ho Cho, Hamin Shin, Jaewan Ahn, Dogyeong Jeon, Jihan Kim, Sung-Yool Choi, Il-Doo Kim
Summary: This paper reports an ultrafast flash-thermal shock (FTS)-induced annealing technique for the preparation of single-atom-stabilized N-doped graphene in an ambient-air environment. The method offers advantages such as high throughput, large area, and vacuum-free manufacturing of single-atom catalysts. Experimental results demonstrate that the single-atom-stabilized N-doped graphene produced by this method exhibits excellent chemiresistive gas sensing capabilities and electrocatalytic activities.
Article
Chemistry, Multidisciplinary
Jun-Hwe Cha, Su-Ho Cho, Dong-Ha Kim, Dogyeong Jeon, Seohak Park, Ji-Won Jung, Il-Doo Kim, Sung-Yool Choi
Summary: High-entropy alloys (HEAs) have unique physicochemical properties compared to unary nanoparticles (NPs). Conventional alloying guidelines limit the possible combinations of alloying elements, but recent research has shown that carbon thermal shocks (CTS) and a high-entropy environment play a critical role in HEA synthesis. This study proposes a photo-thermal approach using carbon nanofibers to successfully synthesize HEA NPs with up to nine elements, demonstrating high activity and stability in water splitting reactions.
ADVANCED MATERIALS
(2023)
Article
Chemistry, Multidisciplinary
Inseong Lee, Mingu Kang, Seohak Park, Cheolmin Park, Hyeonji Lee, Sanggeun Bae, Hyeongjin Lim, Sungkyu Kim, Woonggi Hong, Sung-Yool Choi
Summary: This study proposes a method to heal donor defect states in monolayer MoS2 using oxygen plasma, with an aluminum oxide (Al2O3) barrier layer that protects the MoS2 channel from damage. The successful healing of donor defect states in MoS2 by oxygen atoms, even in the presence of an Al2O3 barrier layer, has been confirmed. The proposed method enhances the channel properties of MoS2.
Article
Nanoscience & Nanotechnology
Hyeok Jun Jin, Cheolmin Park, Hyo Hoon Byun, Seo Hak Park, Sung-Yool Choi
Summary: A multicolor imaging system using a two-dimensional van der Waals MoTe2/MoS2 heterostructure has been developed, achieving high responsivity within ultra-broadband for high-resolution photodetection. The system is capable of detecting and identifying target objects at visible-to-infrared wavelengths, with fast photoresponse time and unique cutoff wavelengths.
Article
Chemistry, Multidisciplinary
Cheolmin Park, Woonggi Hong, Sung-Yool Choi
Summary: By using thermal process, the high defect concentration in a large area (2 x 2 cm(2)) few-layer MoS2 (2.3 nm thick) was uniformly repaired. The defect concentration of the healed sample decreased by 3.8 times, and both the PL intensity and field-effect mobility over the entire area increased by more than two times.
ADVANCED MATERIALS INTERFACES
(2023)
Article
Chemistry, Multidisciplinary
Jungyeop Oh, Sang Yoon Yang, Sungkyu Kim, Changhyeon Lee, Jun-Hwe Cha, Byung Chul Jang, Sung Gap Im, Sung-Yool Choi
Summary: This study proposes a novel method to enhance the stability and controllability of conductive filaments by introducing imidazole groups that boost the nucleation of Cu nanoclusters in the ultrathin polymer switching layer through the initiated chemical vapor deposition (iCVD) process. It is confirmed that conductive filaments based on nanoclusters with specific gaps are generated in the copolymer medium using this method. Furthermore, by modulating the tunneling gaps, an ultra-wide conductance range of analog tunable conductive filaments is achieved from several hundreds of nS to a few mS with a sub-1 V driving voltage. This approach paves the way for the extension of state availability in synaptic devices to overcome the tunability-stability dilemma, which is essential for the synaptic elements in neuromorphic systems.
MATERIALS HORIZONS
(2023)
