Publications by authors named "Kyung-Eun Byun"

18 Publications

  • Page 1 of 1

Triboelectric Series of 2D Layered Materials.

Adv Mater 2018 Sep 16;30(39):e1801210. Epub 2018 Aug 16.

Samsung Advanced Institute of Technology, Suwon, 443-803, Republic of Korea.

Recently, as applications based on triboelectricity have expanded, understanding the triboelectric charging behavior of various materials has become essential. This study investigates the triboelectric charging behaviors of various 2D layered materials, including MoS , MoSe , WS , WSe , graphene, and graphene oxide in a triboelectric series using the concept of a triboelectric nanogenerator, and confirms the position of 2D materials in the triboelectric series. It is also demonstrated that the results are obviously related to the effective work functions. The charging polarity indicates the similar behavior regardless of the synthetic method and film thickness ranging from a few hundred nanometers (for chemically exfoliated and restacked films) to a few nanometers (for chemical vapor deposited films). Further, the triboelectric charging characteristics could be successfully modified via chemical doping. This study provides new insights to utilize 2D materials in triboelectric devices, allowing thin and flexible device fabrication.
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http://dx.doi.org/10.1002/adma.201801210DOI Listing
September 2018

Two-Dimensional Materials Inserted at the Metal/Semiconductor Interface: Attractive Candidates for Semiconductor Device Contacts.

Nano Lett 2018 08 26;18(8):4878-4884. Epub 2018 Jul 26.

Samsung Advanced Institute of Technology , Suwon 443-803 , Republic of Korea.

Metal-semiconductor junctions are indispensable in semiconductor devices, but they have recently become a major limiting factor precluding device performance improvement. Here, we report the modification of a metal/n-type Si Schottky contact barrier by the introduction of two-dimensional (2D) materials of either graphene or hexagonal boron nitride (h-BN) at the interface. We realized the lowest specific contact resistivities (ρ) of 3.30 nΩ cm (lightly doped n-type Si, ∼ 10/cm) and 1.47 nΩ cm (heavily doped n-type Si, ∼ 10/cm) via 2D material insertion are approaching the theoretical limit of 1.3 nΩ cm. We demonstrated the role of the 2D materials at the interface in achieving a low ρ value by the following mechanisms: (a) 2D materials effectively form dipoles at the metal-2D material (M/2D) interface, thereby reducing the metal work function and changing the pinning point, and (b) the fully metalized M/2D system shifts the pinning point toward the Si conduction band, thus decreasing the Schottky barrier. As a result, the fully metalized M/2D system using atomically thin and well-defined 2D materials shows a significantly reduced ρ. The proposed 2D material insertion technique can be used to obtain extremely low contact resistivities in metal/n-type Si systems and will help to achieve major performance improvements in semiconductor technologies.
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http://dx.doi.org/10.1021/acs.nanolett.8b01509DOI Listing
August 2018

Control of Triboelectrification by Engineering Surface Dipole and Surface Electronic State.

ACS Appl Mater Interfaces 2016 Jul 5;8(28):18519-25. Epub 2016 Jul 5.

Samsung Advanced Institute of Technology , Suwon 443-803, Republic of Korea.

Although triboelectrification is a well-known phenomenon, fundamental understanding of its principle on a material surface has not been studied systematically. Here, we demonstrated that the surface potential, especially the surface dipoles and surface electronic states, governed the triboelectrification by controlling the surface with various electron-donating and -withdrawing functional groups. The functional groups critically affected the surface dipoles and surface electronic states followed by controlling the amount of and even the polarity of triboelectric charges. As a result, only one monolayer with a thickness of less than 1 nm significantly changed the conventional triboelectric series. First-principles simulations confirmed the atomistic origins of triboelectric charges and helped elucidate the triboelectrification mechanism. The simulation also revealed for the first time where charges are retained after triboelectrification. This study provides new insights to understand triboelectrification.
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http://dx.doi.org/10.1021/acsami.6b02802DOI Listing
July 2016

Polythiophene nanofibril bundles surface-embedded in elastomer: a route to a highly stretchable active channel layer.

Adv Mater 2015 Feb 7;27(7):1255-61. Epub 2015 Jan 7.

Department of Materials Science and Engineering, Yonsei University, 134 Shinchon, dong, Seoul, Korea.

A stretchable polymer channel layer for organic field-effect transistors is obtained by spin-coating a blend solution of polythiophene and rubber polymer. A network of the polythiophene nanofibril bundles surface-embedded in the rubber matrix allows large stretchability of the polythiophene film layer.
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http://dx.doi.org/10.1002/adma.201404602DOI Listing
February 2015

Highly stretchable resistive pressure sensors using a conductive elastomeric composite on a micropyramid array.

Adv Mater 2014 Jun 17;26(21):3451-8. Epub 2014 Feb 17.

Samsung Advanced Institute of Technology (SAIT), Samsung Electronics Company, San 14, Nongseo-dong, Giheung-gu, Yongin-si, Gyeonggi-do, Korea.

A stretchable resistive pressure sensor is achieved by coating a compressible substrate with a highly stretchable electrode. The substrate contains an array of microscale pyramidal features, and the electrode comprises a polymer composite. When the pressure-induced geometrical change experienced by the electrode is maximized at 40% elongation, a sensitivity of 10.3 kPa(-1) is achieved.
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http://dx.doi.org/10.1002/adma.201305182DOI Listing
June 2014

A flexible bimodal sensor array for simultaneous sensing of pressure and temperature.

Adv Mater 2014 Feb 23;26(5):796-804. Epub 2013 Oct 23.

School of Advanced Materials Science & Engineering and Sungkyunkwan University, Suwon, Kyunggi-do, 440-746, Republic of Korea.

Diverse signals generated from the sensing elements embedded in flexible electronic skins (e-skins) are typically interfered by strain energy generated through processes such as touching, bending, stretching or twisting. Herein, we demonstrate a flexible bimodal sensor that can separate a target signal from the signal by mechanical strain through the integration of a multi-stimuli responsive gate dielectric and semiconductor channel into the single field-effect transistor (FET) platform.
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http://dx.doi.org/10.1002/adma.201302869DOI Listing
February 2014

Graphene and thin-film semiconductor heterojunction transistors integrated on wafer scale for low-power electronics.

Nano Lett 2013 25;13(12):5967-71. Epub 2013 Nov 25.

Samsung Advanced Institute of Technology, Samsung Electronics Co. , 97 Samsung2-ro, Giheung-gu, Yongin-si, Gyeonggi-do 446-712, Korea.

Graphene heterostructures in which graphene is combined with semiconductors or other layered 2D materials are of considerable interest, as a new class of electronic devices has been realized. Here we propose a technology platform based on graphene-thin-film-semiconductor-metal (GSM) junctions, which can be applied to large-scale and power-efficient electronics compatible with a variety of substrates. We demonstrate wafer-scale integration of vertical field-effect transistors (VFETs) based on graphene-In-Ga-Zn-O (IGZO)-metal asymmetric junctions on a transparent 150 × 150 mm(2) glass. In this system, a triangular energy barrier between the graphene and metal is designed by selecting a metal with a proper work function. We obtain a maximum current on/off ratio (Ion/Ioff) up to 10(6) with an average of 3010 over 2000 devices under ambient conditions. For low-power logic applications, an inverter that combines complementary n-type (IGZO) and p-type (Ge) devices is demonstrated to operate at a bias of only 0.5 V.
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http://dx.doi.org/10.1021/nl403142vDOI Listing
September 2014

Graphene for true Ohmic contact at metal-semiconductor junctions.

Nano Lett 2013 Sep 30;13(9):4001-5. Epub 2013 Aug 30.

Samsung Advanced Institute of Technology, Samsung Electronics Co. , Yongin-si 446-712, Korea.

The rectifying Schottky characteristics of the metal-semiconductor junction with high contact resistance have been a serious issue in modern electronic devices. Herein, we demonstrated the conversion of the Schottky nature of the Ni-Si junction, one of the most commonly used metal-semiconductor junctions, into an Ohmic contact with low contact resistance by inserting a single layer of graphene. The contact resistance achieved from the junction incorporating graphene was about 10(-8) ~ 10(-9) Ω cm(2) at a Si doping concentration of 10(17) cm(-3).
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http://dx.doi.org/10.1021/nl402367yDOI Listing
September 2013

Graphene nanonet for biological sensing applications.

Nanotechnology 2013 Sep 21;24(37):375302. Epub 2013 Aug 21.

Department of Physics and Astronomy, Seoul National University, Seoul, Korea.

We report a simple but efficient method to fabricate versatile graphene nanonet (GNN)-devices. In this method, networks of V2O5 nanowires (NWs) were prepared in specific regions of single-layer graphene, and the graphene layer was selectively etched via a reactive ion etching method using the V2O5 NWs as a shadow mask. The process allowed us to prepare large scale patterns of GNN structures which were comprised of continuous networks of graphene nanoribbons (GNRs) with chemical functional groups on their edges. The GNN can be easily functionalized with biomolecules for fluorescent biochip applications. Furthermore, electrical channels based on GNN exhibited a rather high mobility and low noise compared with other network structures based on nanostructures such as carbon nanotubes, which was attributed to the continuous connection of nanoribbons in GNN structures. As a proof of concept, we built DNA sensors based on GNN channels and demonstrated the selective detection of DNA. Since our method allows us to prepare high-performance networks of GNRs over a large surface area, it should open up various practical biosensing applications.
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http://dx.doi.org/10.1088/0957-4484/24/37/375302DOI Listing
September 2013

Electrical control of kinesin-microtubule motility using a transparent functionalized-graphene substrate.

Nanotechnology 2013 May 17;24(19):195102. Epub 2013 Apr 17.

Department of Biophysics and Chemical Biology, Seoul National University, Seoul, Korea.

We report a new strategy to selectively localize and control microtubule translocation via electrical control of microtubules using a microfabricated channel on a functionalized-graphene electrode with high transparency and conductivity. A patterned SU-8 film acts as an insulation layer which shields the electrical field generated by the graphene underneath while the localized electric field on the exposed graphene surface guides the negatively charged microtubules. This is the first report showing that functionalized graphene can support and control microtubule motility.
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http://dx.doi.org/10.1088/0957-4484/24/19/195102DOI Listing
May 2013

Graphene barristor, a triode device with a gate-controlled Schottky barrier.

Science 2012 Jun 17;336(6085):1140-3. Epub 2012 May 17.

Graphene Research Center, Samsung Advanced Institute of Technology, Yongin 446-712, Korea.

Despite several years of research into graphene electronics, sufficient on/off current ratio I(on)/I(off) in graphene transistors with conventional device structures has been impossible to obtain. We report on a three-terminal active device, a graphene variable-barrier "barristor" (GB), in which the key is an atomically sharp interface between graphene and hydrogenated silicon. Large modulation on the device current (on/off ratio of 10(5)) is achieved by adjusting the gate voltage to control the graphene-silicon Schottky barrier. The absence of Fermi-level pinning at the interface allows the barrier's height to be tuned to 0.2 electron volt by adjusting graphene's work function, which results in large shifts of diode threshold voltages. Fabricating GBs on respective 150-mm wafers and combining complementary p- and n-type GBs, we demonstrate inverter and half-adder logic circuits.
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http://dx.doi.org/10.1126/science.1220527DOI Listing
June 2012

Graphene-polymer hybrid nanostructure-based bioenergy storage device for real-time control of biological motor activity.

ACS Nano 2011 Nov 28;5(11):8656-64. Epub 2011 Oct 28.

Department of Physics and Astronomy, Seoul National University, Seoul, 151-742 Korea.

We report a graphene-polymer hybrid nanostructure-based bioenergy storage device to turn on and off biomotor activity in real-time. In this strategy, graphene was functionalized with amine groups and utilized as a transparent electrode supporting the motility of biomotors. Conducting polymer patterns doped with adenosine triphosphate (ATP) were fabricated on the graphene and utilized for the fast release of ATP by electrical stimuli through the graphene. The controlled release of biomotor fuel, ATP, allowed us to control the actin filament transportation propelled by the biomotor in real-time. This strategy should enable the integrated nanodevices for the real-time control of biological motors, which can be a significant stepping stone toward hybrid nanomechanical systems based on motor proteins.
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http://dx.doi.org/10.1021/nn202421nDOI Listing
November 2011

Scanning noise microscopy on graphene devices.

ACS Nano 2011 Nov 6;5(11):8620-8. Epub 2011 Oct 6.

Department of Physics and Astronomy,Seoul National University, Seoul 151-747, Korea.

We developed a scanning noise microscopy (SNM) method and demonstrated the nanoscale noise analysis of a graphene strip-based device. Here, a Pt tip made a direct contact on the surface of a nanodevice to measure the current noise spectrum through it. Then, the measured noise spectrum was analyzed by an empirical model to extract the noise characteristics only from the device channel. As a proof of concept, we demonstrated the scaling behavior analysis of the noise in graphene strips. Furthermore, we performed the nanoscale noise mapping on a graphene channel, allowing us to study the effect of structural defects on the noise of the graphene channel. The SNM method is a powerful tool for nanoscale noise analysis and should play a significant role in basic research on nanoscale devices.
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http://dx.doi.org/10.1021/nn202135gDOI Listing
November 2011

Polarization-controlled differentiation of human neural stem cells using synergistic cues from the patterns of carbon nanotube monolayer coating.

ACS Nano 2011 Jun 13;5(6):4704-11. Epub 2011 May 13.

Interdisciplinary Program in Nano-Science and Technology, Seoul National University, Seoul 151-747, Korea.

We report a method for selective growth and structural-polarization-controlled neuronal differentiation of human neural stem cells (hNSCs) into neurons using carbon nanotube network patterns. The CNT patterns provide synergistic cues for the differentiation of hNSCs in physiological solution and an optimal nanotopography at the same time with good biocompatibility. We demonstrated a polarization-controlled neuronal differentiation at the level of individual NSCs. This result should provide a stable and versatile platform for controlling the hNSC growth because CNT patterns are known to be stable in time unlike commonly used organic molecular patterns.
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http://dx.doi.org/10.1021/nn2006128DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3125501PMC
June 2011

Dual transport systems based on hybrid nanostructures of microtubules and actin filaments.

Small 2011 Jul 12;7(13):1755-60. Epub 2011 May 12.

Department of Nano Science and Engineering, Seoul National University, Seoul, 151-747, Korea.

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http://dx.doi.org/10.1002/smll.201002267DOI Listing
July 2011

Functionalization of silicon nanowires with actomyosin motor protein for bioinspired nanomechanical applications.

Small 2009 Dec;5(23):2659-64

Department of Physics and Astronomy, Seoul National University, Seoul, Korea.

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http://dx.doi.org/10.1002/smll.200900964DOI Listing
December 2009

Selective assembly and guiding of actomyosin using carbon nanotube network monolayer patterns.

Langmuir 2007 Sep 18;23(19):9535-9. Epub 2007 Aug 18.

Physics and Astronomy, Seoul National University, Shilim-Dong, Kwanak-Gu, Seoul, Korea.

We report a new method for the selective assembly and guiding of actomyosin using carbon nanotube patterns. In this method, monolayer patterns of the single-walled carbon nanotube (swCNT) network were prepared via the self-limiting mechanism during the directed assembly process, and they were used to block the adsorption of both myosin and actin filaments on specific substrate regions. The swCNT network patterns were also used as an efficient barrier for the guiding experiments of actomyosin. This is the first result showing that inorganic nanostructures such as carbon nanotubes can be used to control the adsorption and activity of actomyosin. This strategy is advantageous over previous methods because it does not require complicated biomolecular linking processes and nonbiological nanostructures are usually more stable than biomolecular linkers.
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http://dx.doi.org/10.1021/la7019318DOI Listing
September 2007

Selective assembly and alignment of actin filaments with desired polarity on solid substrates.

Langmuir 2006 Oct;22(21):8635-8

Department of Physics and MARTECH, Florida State University, Tallahassee, Florida 32306, USA.

We report a new strategy to selectively assemble and align filamentous actin (F-actin) onto desired locations on a solid substrate with a specific structural polarity. In this strategy, biotinylated gelsolin caps the structural minus end of F-actin so that the F-actin binds onto a streptavidin pattern with a specific structural polarity. We also demonstrate that an electric field can be utilized to align bound F-actin along a desired direction. This can be one of the major technical breakthroughs toward the assembly of nanomechanical systems based on myosin biomotors.
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http://dx.doi.org/10.1021/la061008aDOI Listing
October 2006