A5100622996- 2D Materials and Applications
- Graphene research and applications
- Perovskite Materials and Applications
- ZnO doping and properties
- MXene and MAX Phase Materials
- Advanced Memory and Neural Computing
- GaN-based semiconductor devices and materials
- Ga2O3 and related materials
- Molecular Junctions and Nanostructures
- Nanowire Synthesis and Applications
- Advanced Sensor and Energy Harvesting Materials
- Complex Network Analysis Techniques
- Quantum Dots Synthesis And Properties
- Electrocatalysts for Energy Conversion
- Ferroelectric and Negative Capacitance Devices
- Conducting polymers and applications
- Semiconductor materials and devices
- Advanced Photocatalysis Techniques
- Chalcogenide Semiconductor Thin Films
- Quantum and electron transport phenomena
- Topological Materials and Phenomena
- Semiconductor Quantum Structures and Devices
- Supercapacitor Materials and Fabrication
- Markov Chains and Monte Carlo Methods
- Stochastic processes and statistical mechanics
Seoul National University
2010-2024
Korea University
2014-2023
Korea Institute of Science and Technology
2021-2023
Seoul Institute
2017-2020
Florida Institute of Technology
2015-2019
Government of the Republic of Korea
2016-2018
PRG S&Tech (South Korea)
2017-2018
Samsung (South Korea)
2015
North Carolina State University
2012-2014
Columbia University
2013-2014
Atomically thin forms of layered materials, such as conducting graphene, insulating hexagonal boron nitride (hBN), and semiconducting molybdenum disulfide (MoS2), have generated great interests recently due to the possibility combining diverse atomic layers by mechanical "stacking" create novel materials devices. In this work, we demonstrate field-effect transistors (FETs) with MoS2 channels, hBN dielectric, graphene gate electrodes. These devices show mobilities up 45 cm(2)/Vs operating...
To design fast neural networks, many works have been focusing on reducing the number of floating-point operations (FLOPs). We observe that such reduction in FLOPs, however, does not necessarily lead to a similar level re-duction latency. This mainly stems from inefficiently low per second (FLOPS). achieve faster we revisit popular operators and demonstrate FLOPS is due frequent memory access operators, especially depthwise con-volution. hence propose novel partial convolution (PConv)...
We fabricated transferable gallium nitride (GaN) thin films and light-emitting diodes (LEDs) using graphene-layered sheets. Heteroepitaxial were grown on graphene layers by high-density, vertically aligned zinc oxide nanowalls as an intermediate layer. The show excellent optical characteristics at room temperature, such stimulated emission. As one of the examples for device applications, LEDs that emit strong electroluminescence emission under illumination fabricated. Furthermore, layered...
Emerging two-dimensional (2D) semiconductors such as molybdenum disulfide (MoS2) have been intensively studied because of their novel properties for advanced electronics and optoelectronics. However, 2D materials are by nature sensitive to environmental influences, temperature, humidity, adsorbates, trapped charges in neighboring dielectrics. Therefore, it is crucial develop device architectures that provide both high performance long-term stability. Here we report dual-gated van der Waals...
Visible-color-tunable light-emitting diodes (LEDs) with electroluminescent color that changes continuously from red to blue by adjusting the external electric bias are fabricated using multifacetted GaN nanorods anisotropically formed 3D InGaN multiple-quantum wells. Monolithically integrated red, green, and LEDs on a single substrate, operating at fixed drive current, also demonstrated for inorganic full-color LED display applications.
Two-dimensional (2D) semiconductors hold promises for electronic and optoelectronic applications due to their outstanding electrical optical properties. Despite a short research history, wide range of 'proof-of-concept' devices based on 2D materials have been demonstrated, highlighting impact in advanced technology. Here we review the unique properties semiconducting terms devices. We summarize all engineering issues devices, including material quality, dielectric, contacts. also discuss...
Perovskite solar cells (PSCs) based on organic monovalent cation (methylammonium or formamidinium) have shown excellent optoelectronic properties with high efficiencies above 22%, threatening the status of silicon cells. However, critical issues long‐term stability to be solved for commercialization. The severe weakness state‐of‐the‐art PSCs against moisture originates mainly from hygroscopic cations. Here, rubidium (Rb) is suggested as a promising candidate an inorganic–organic mixed system...
Wafer-scale n-MoS<sub>2</sub>/p-Si photocathodes with high hydrogen evolution reaction activities are demonstrated.
Copper-indium-selenide (CISe) quantum dots (QDs) are a promising alternative to the toxic cadmium- and lead-chalcogenide QDs generally used in photovoltaics due their low toxicity, narrow band gap, high absorption coefficient. Here, we demonstrate that photovoltaic performance of CISe QD-sensitized solar cells (QDSCs) can be greatly enhanced simply by optimizing thickness ZnS overlayers on TiO2 electrodes. By roughly doubling compared conventional one, conversion efficiency is about 40%....
The development of energy-efficient artificial synapses capable manifoldly tuning synaptic activities can provide a significant breakthrough toward novel neuromorphic computing technology. Here, new class architecture, three-terminal device consisting vertically integrated monolithic tungsten oxide memristor, and variable-barrier selenide/graphene Schottky diode, termed as 'synaptic barrister,' are reported. implement essential characteristics, such short-term plasticity, long-term...
Epitaxial van der Waals (vdW) heterostructures of organic and layered materials are demonstrated to create high-performance electronic devices. High-quality rubrene films with large single-crystalline domains grown on h-BN dielectric layers via vdW epitaxy. In addition, high carrier mobility comparable free-standing single-crystal counterparts is achieved by forming interfacial electrical contacts graphene electrodes. As a service our authors readers, this journal provides supporting...
2D semiconductors, including transition metal dichalcogenides (TMDs), have been widely studied recently. However, the device performance is deteriorated due to significant contact resistance. The resistance of MoS2-metal contacts decreases with thickness MoS2. We obtained a Schottky barrier height as low about 70 meV when MoS2 trilayer-thick. It important find optimal choice and layer
Graph sampling via crawling has been actively considered as a generic and important tool for collecting uniform node samples so to consistently estimate uncover various characteristics of complex networks. The so-called simple random walk with re-weighting (SRW-rw) Metropolis-Hastings (MH) algorithm have popular in the literature such unbiased graph sampling. However, an unavoidable downside their core walks -- slow diffusion over space, can cause poor estimation accuracy. In this paper, we...
Short-chain aminosilanes, namely, bis(N,N-dimethylamino)dimethylsilane (DMADMS) and (N,N-dimethylamino)trimethylsilane (DMATMS), have been used as Si precursors for atomic layer deposition (ALD) of SiO2. In this work, the DMADMS DMATMS are utilized inhibitors area-selective ALD (AS-ALD). The selectively adsorb on a SiO2 surface but not H–Si, so that becomes deactivated toward subsequent ALD. deactivation by was investigated using various experimental theoretical methods, including potential...
There have been rapidly increasing demands for flexible lighting apparatus, and micrometer-scale light-emitting diodes (LEDs) are regarded as one of the promising sources deformable device applications. Herein, we demonstrate a method creating LED, based on remote heteroepitaxy GaN microrod (MR) p-n junction arrays c-Al2O3 wafer across graphene. The use graphene allows transfer MR LED onto copper plate, spatially separate offer ideal geometry suitable in various shapes without serious...
For practical applications of high-performance supercapacitors as wearable energy storage devices attached to skin or clothes, the are recommended have stable mechanical and electrochemical performances during dynamic deformations, including stretching, due real-time movements human body. In this work, we demonstrate a skin-like, dynamically stretchable, planar supercapacitor (SPS). The SPS consists buckled manganese/molybdenum (Mn/Mo) mixed oxide@multiwalled carbon nanotube (MWCNT)...
Although neurotransmitters are key substances closely related to evaluating degenerative brain diseases as well regulating essential functions in the body, many research efforts have not been focused on direct observation of such biochemical messengers, rather monitoring relatively associated physical, mechanical, and electrophysiological parameters. Here, a bioresorbable silicon-based neurochemical analyzer incorporated with 2D transition metal dichalcogenides is introduced completely...
Heterosynaptic neuromodulation is a key enabler for energy-efficient and high-level biological neural processing. However, such manifold synaptic modulation cannot be emulated using conventional memristors transistors. Thus, reported herein three-terminal heterosynaptic memtransistor an intentional-defect-generated molybdenum disulfide channel. Particularly, the defect-mediated space-charge-limited conduction in ultrathin channel results memristive switching characteristics between source...
Assembling solution-processed van der Waals (vdW) materials into thin films holds great promise for constructing large-scale, high-performance thin-film electronics, especially at low temperatures. While transition metal dichalcogenide assembled in solution have shown potential as channel materials, fully vdW electronics not been achieved due to the absence of suitable dielectric and high-temperature processing. In this work, we report on all-solution-processedvdW transistors (TFTs)...