- Advanced Memory and Neural Computing
- Organic Electronics and Photovoltaics
- Ferroelectric and Negative Capacitance Devices
- Conducting polymers and applications
- 2D Materials and Applications
- Advanced Sensor and Energy Harvesting Materials
- Semiconductor materials and devices
- Graphene research and applications
- Neural dynamics and brain function
- Perovskite Materials and Applications
- Neuroscience and Neural Engineering
- MXene and MAX Phase Materials
- ZnO doping and properties
- Transition Metal Oxide Nanomaterials
- Photoreceptor and optogenetics research
- Nanowire Synthesis and Applications
- Machine Learning and ELM
- Thermal properties of materials
- Carbon Nanotubes in Composites
- Electronic and Structural Properties of Oxides
- Analytical Chemistry and Sensors
- TiO2 Photocatalysis and Solar Cells
- Tactile and Sensory Interactions
- Molecular Junctions and Nanostructures
- Radiation Effects in Electronics
Kwangwoon University
2024
Korea University
2019-2024
Korea Institute of Science and Technology
2018-2020
Seoul National University
2013-2018
Institute of Applied Physics
2015
University of Seoul
2015
We investigated the physical properties of molybdenum disulfide (MoS2) atomic crystals with a sulfur vacancy passivation after treatment alkanethiol molecules including their electrical, Raman, and photoluminescence (PL) characteristics. MoS2, one transition metal dichalcogenide materials, is promising two-dimensional semiconductor material good properties. It known that vacancies exist in resulting n-type behavior MoS2. The on MoS2 surface tend to form covalent bonds sulfur-containing...
We investigated the gate bias stress effects of multilayered MoS2 field effect transistors (FETs) with a back-gated configuration. The electrical stability FETs can be significantly influenced by type, relative sweep rate, and time in an ambient environment. Specifically, when positive was applied to FET, current device decreased its threshold shifted direction. In contrast, negative stress, increased were enhanced for longer or slower rate used. These phenomena explained charge trapping due...
One-dimensional (1D) devices are becoming the most desirable format for wearable electronic technology because they can be easily woven into (e-) textile(s) with versatile functional units while maintaining their inherent features under mechanical stress. In this study, we designed 1D fiber-shaped multi-synapses comprising ferroelectric organic transistors fabricated on a 100-μm Ag wire and used them as multisynaptic channels in an e-textile neural network neuromorphic applications. The...
A wide reservoir computing system is an advanced architecture composed of multiple layers in parallel, which enables more complex and diverse internal dynamics for time-series information processing. However, its hardware implementation has not yet been realized due to the lack a high-performance physical complexity fabricating stacks. Here, we achieve proof-of-principle demonstration such made multilayered three-dimensional stacked 3 × 10 tungsten oxide memristive crossbar array, with...
We investigated the effects of passivation on electrical characteristics molybdenum disulfide (MoS(2)) field effect transistors (FETs) under nitrogen, vacuum, and oxygen environments. When MoS(2) FETs were exposed to oxygen, on-current decreased threshold voltage shifted in positive gate bias direction as a result electrons being trapped by adsorbed at surface. In contrast, properties changed only slightly different environments when layer was created using polymethyl methacrylate (PMMA)....
Recently, two-dimensional materials such as molybdenum disulfide (MoS2) have been extensively studied channel for field effect transistors (FETs) because MoS2 has outstanding electrical properties a low subthreshold swing value, high on/off ratio, and good carrier mobility. In this study, we characterized the photo-responsive of FET when stacking p-type organic copper phthalocyanine (CuPc) layer on surface. We observed that threshold voltage could be controlled by CuPc layers due to charge...
We investigated the trap-mediated electronic transport properties of pentacene/molybdenum disulphide (MoS2) p-n heterojunction devices. observed that hybrid heterojunctions were gate-tunable and strongly affected by trap-assisted tunnelling through van der Waals gap at interfaces between MoS2 pentacene. The pentacene/MoS2 diodes had high ideality factor, which resulted from conduction nature From temperature-variable current-voltage measurement, a space-charge-limited variable range hopping...
Abstract Realization of memristor‐based neuromorphic hardware system is important to achieve energy efficient bigdata processing and artificial intelligence in integrated device system‐level. In this sense, uniform reliable titanium oxide (TiO x ) memristor array devices are fabricated be utilized as constituent element neural network, representing passive matrix structure enabling vector‐matrix multiplication process between multisignal trained synaptic weight. particular, situ...
We investigated the photoconductive characteristics of molybdenum disulfide (MoS2) field-effect transistors (FETs) that were fabricated with mechanically exfoliated multi-layer MoS2 flakes. Upon exposure to UV light, we observed an increase in FET current because electron–hole pair generation. The decayed after light was turned off. decay processes fitted using exponential functions different characteristics. Specifically, a fast used at early stages immediately turning off account for...
High-quality channel layer is required for next-generation flexible electronic devices. Graphene a good candidate due to its high carrier mobility and unique ambipolar transport characteristics but typically shows low on/off ratio caused by gapless band structure. Popularly investigated organic semiconductors, such as pentacene, suffer from poor mobility. Here, we propose graphene/pentacene with high-k ion-gel gate dielectric. The device both well excellent mechanical flexibility. Most...
One of the long-standing problems in field organic electronics is their instability an open environment, especially poor water resistance. For reliable operation devices, introducing effective protection layer using organo-compatible materials and processes highly desirable. Here, we report a facile method for depositing superhydrophobic on semiconductors under ambient conditions. The exhibiting excellent water-repellent self-cleaning properties was deposited onto directly dip-coating...
Photoswitching response times (rise and decay times) of a vertical organic inorganic heterostructure with p-type copper phthalocyanine (CuPc) n-type molybdenum disulfide (MoS2) semiconductors are investigated. By stacking CuPc layer on MoS2 field effect transistors, better photodetection capability fast photoswitching rise phenomena observed. Specifically, 2 nm-thick the channel, time decreases from 3.57 s to 0.18 s. The layer, as passivation prevents absorption oxygen surface channel which...
Abstract Multilayer aluminum oxide (Al 2 O 3 ) resistive memory devices, exhibiting robust switching properties fabricated on a flexible polyethylene naphthalate substrate using only physical vapor deposition methods at room temperature, are reported here. Improved reliability and of the multilayer Al devices observed compared to those single‐layer with assistance guide filament formed in bottom layer. The exhibit nonvolatile bipolar high ON/OFF ratio (>10 4 ), DC sweep endurance cycles...
We studied noise characteristics of a nanocomposite polyimide (PI) and phenyl-C61-butyric acid methyl ester (PCBM) (denoted as PI:PCBM), composite for the organic nonvolatile resistive memory material. The current fluctuations were investigated over bias range that covers various intermediate states negative differential resistance (NDR) in unipolar devices. From analysis 1/f(γ) type noises, scaling behavior between relative power spectral density S̃ R was observed, indicating percolating...
Abstract The origin of negative differential resistance (NDR) and its derivative intermediate resistive states (IRSs) nanocomposite memory systems have not been clearly analyzed for the past decade. To address this issue, we investigate current fluctuations organic devices with NDR IRSs under various temperature conditions. 1/f noise scaling behaviors at conditions in telegraphic indicate localized pathways layers each IRS. observed a long characteristic time low indicates that are...
Three-terminal neuromorphic transistors have garnered considerable attention owing to their superior learning and recognition capabilities in neural computing. For efficient rapid computing of parallel arithmetic unstructured large-sized data, a high-synaptic channel conductance (G) (i.e., synaptic weight) large dynamic range (DR) weight update) are necessary. In this study, we successfully fabricated high-performance all-solution-processed by employing thiol–ene photoclick chemistry-based,...
Micro-scale pentacene organic field effect transistors (OFETs) were fabricated on a flexible poly(ethylene terephthalate) (PET) substrate. By applying highly fluorinated developing solvents and its compatible photoresist materials, it has become possible to make the micro-scale patterning for devices using standard photolithography without damaging underlying polymer layers. The OFETs with 3 μm-sized channel length exhibited stable electrical characteristics under bent configurations large...
Fluorous materials are receiving significant attention as photolithographic that can be used in fabrication processes, particular organic electronic devices, due to their material advantages such orthogonality most materials, non-flammability and low toxicity. Compared with conventional which generally cause chemical damage fluorous construct micro-scale patterned device architecture on devices without physical electrical advantageous properties. developments have improved solvents imaging...
The energy consumption during the operation of organic nonvolatile memory devices fabricated on a flexible polyethylene naphthalate (PEN) substrate is investigated. For bistable resistive devices, applied external voltage and time are essential factors for switching cell from OFF to ON state because amounts determine needed set cell. Using composite material polyimide (PI) [6,6]‐phenyl‐C 61 butyric acid methyl ester (PCBM) as active layer PEN substrate, unipolar behavior good electrical...