A5021376791- Quantum and electron transport phenomena
- Graphene research and applications
- Physics of Superconductivity and Magnetism
- Advancements in Semiconductor Devices and Circuit Design
- Thermal properties of materials
- 2D Materials and Applications
- Surface and Thin Film Phenomena
- Thermal Radiation and Cooling Technologies
- Electronic and Structural Properties of Oxides
- Magnetic and transport properties of perovskites and related materials
- Quantum Information and Cryptography
- Nanowire Synthesis and Applications
- Advanced Condensed Matter Physics
- Semiconductor materials and devices
- Carbon Nanotubes in Composites
- Semiconductor Quantum Structures and Devices
- Superconductivity in MgB2 and Alloys
- Topological Materials and Phenomena
- Mechanical and Optical Resonators
- Molecular Junctions and Nanostructures
- Advanced Thermodynamics and Statistical Mechanics
- Advanced Electrical Measurement Techniques
- Iron-based superconductors research
- Advanced Thermoelectric Materials and Devices
- Advanced Memory and Neural Computing
Korea Research Institute of Standards and Science
2016-2025
Korea University of Science and Technology
2015-2023
Korea Advanced Institute of Science and Technology
2021-2022
Korea Institute of Science and Technology
2022
Government of the Republic of Korea
2018
University of Science and Technology
2018
Daejeon University
2018
University of Illinois Urbana-Champaign
2008-2016
Institute of Micro and Nanotechnology
2010
Pohang University of Science and Technology
2002-2008
We examine mobility and saturation velocity in graphene on SiO2 above room temperature (300-500 K) at high fields (~1 V/um). Data are analyzed with practical models including gated carriers, thermal generation, "puddle" charge, Joule heating. Both decrease rising 300 K, carrier density 2x10^12 cm^-2. Saturation is >3x10^7 cm/s low density, remains greater than Si up to 1.2x10^13 Transport appears primarily limited by the substrate, but results suggest intrinsic could be more twice that observed here.
We report on fabrication and electrical characteristics of high-mobility field-effect transistors (FETs) using ZnO nanorods. For FET fabrications, single-crystal nanorods were prepared catalyst-free metalorganic vapor phase epitaxy. Although typical nanorod FETs exhibited good characteristics, with a transconductance ∼140nS mobility 75cm2∕Vs, the device significantly improved by coating polyimide thin layer surface, exhibiting large turn-ON/OFF ratio 104–105, high 1.9μS, electron above...
This paper describes the fabrication and design principles for using transparent graphene interconnects in stretchable arrays of microscale inorganic light emitting diodes (LEDs) on rubber substrates. We demonstrate several appealing properties this purpose, including its ability to spontaneously conform significant surface topography, a manner that yields effective contacts even deep, recessed device regions. Mechanics modeling reveals fundamental aspects process, as well use same layers...
We report the thermal conductance G of Au/Ti/graphene/SiO2 interfaces (graphene layers 1 ≤ n 10) typical graphene transistor contacts. find ≈ 25 MW m−2 K−1 at room temperature, four times smaller than a Au/Ti/SiO2 interface, even when = 1. attribute this reduction to resistance Au/Ti/graphene and graphene/SiO2 acting in series. The temperature dependence from 50 T 500 K also indicates that heat is predominantly carried by phonons through these interfaces. Our findings suggest metal contacts...
We report the development of a multilayered graphene-Al(2)O(3) nanopore platform for sensitive detection DNA and DNA-protein complexes. Graphene-Al(2)O(3) nanolaminate membranes are formed by sequentially depositing layers graphene Al(2)O(3), with nanopores being in these using an electron-beam sculpting process. The resulting highly robust, exhibit low electrical noise (significantly lower than pure graphene), to electrolyte pH at KCl concentrations (attributed high buffer capacity...
Polycrystalline graphene sensors easily obtained through chemical vapor deposition (CVD) have been developed for sensing. We show that linear defects or continuous lines of point on these result in significantly higher sensitivity than pristine and carbon nanotube film sensors. Further enhancement is by cutting the into ribbons width comparable to defect dimensions (micrometers).
We directly image hot spot formation in functioning mono- and bilayer graphene field effect transistors (GFETs) using infrared thermal microscopy. Correlating with an electrical-thermal transport model provides insight into carrier distributions, fields, GFET power dissipation. The corresponds to the location of minimum charge density along GFET; by changing applied bias, this can be shifted between electrodes or held middle channel ambipolar transport. Interestingly, shape bears imprint...
A fundamental understanding of chemical sensing mechanisms in graphene-based field-effect transistors (chemFETs) is essential for the development next generation sensors. Here we explore hidden modalities responsible tailoring gas detection ability pristine graphene sensors by exposing chemFETs to electron donor and acceptor trace vapors. We uncover that sensitivity (in terms modulation electrical conductivity) not necessarily intrinsic graphene, but rather it facilitated external defects...
Ultrafast electrically driven nanoscale light sources are critical components in nanophotonics. Compound semiconductor-based for the nanophotonic platforms have been extensively investigated over past decades. However, monolithic ultrafast with a small footprint remain challenge. Here, we demonstrate graphene emitters that achieve pulse generation up to 10 GHz bandwidth across broad spectral range from visible near-infrared. The fast response results charge-carrier dynamics and weak...
A central issue of nanoelectronics concerns their fundamental scaling limits, that is, the smallest and most energy-efficient devices can function reliably. Unlike charge-based electronics are prone to leakage at nanoscale dimensions, memory based on phase change materials (PCMs) more scalable, storing digital information as crystalline or amorphous state a material. Here, we describe novel approach self-align PCM nanowires with individual carbon nanotube (CNT) electrodes for first time. The...
Abstract The achievement of ultraclean Ohmic van der Waals (vdW) contacts at metal/transition-metal dichalcogenide (TMDC) interfaces would represent a critical step for the development high-performance electronic and optoelectronic devices based on two-dimensional (2D) semiconductors. Herein, we report fabrication vdW between indium (In) molybdenum disulfide (MoS 2 ) clarification atomistic origins its Ohmic-like transport properties. Atomically clean In/MoS are achieved by evaporating In...
We demonstrate a reliable technique for counting atomic planes (n) of few-layer graphene (FLG) on SiO2/Si substrates by Raman spectroscopy. Our approach is based measuring the ratio integrated intensity G peak and optical phonon Si, I(G)/I(Si), particularly useful in range n>4 where few methods exist. compare our results with force microscopy (AFM) measurements Fresnel equation calculations. Lastly, we apply method to unambiguously identify n FLG devices find that mobility (~2000 cm2 V-1...
We study graphene nanoribbon (GNR) interconnects obtained from grown by chemical vapor deposition (CVD). report low- and high-field electrical measurements over a wide temperature range, 1.7 to 900 K. Room mobilities range 100 500 cm2·V–1·s–1, comparable GNRs exfoliated graphene, suggesting that bulk defects or grain boundaries play little role in devices smaller than the CVD crystallite size. At high-field, peak current densities are limited Joule heating, but small amount of thermal...
We use infrared thermal imaging and electrothermal simulations to find that localized Joule heating in graphene field-effect transistors on SiO2 is primarily governed by device electrostatics. Hot spots become more (i.e., sharper) as the underlying oxide thickness reduced, such average peak temperatures scale differently, with significant long-term reliability implications. The temperature proportional thickness, but minimized at an of ∼90 nm due competing electrostatic effects. also careful...
With its electrical carrier type as well densities highly sensitive to light, graphene is potentially an ideal candidate for many optoelectronic applications. Beyond the direct light–graphene interactions, indirect effects arising from induced charge traps underneath photoactive light–substrate interactions must be better understood and harnessed. Here, we study local doping effect in using focused-laser irradiation, which governs trapping ejecting behavior of trap sites gate oxide. The...
We use simulations to examine current saturation in sub-micron graphene transistors on SiO2/Si. find self-heating is partly responsible for (lower output conductance), but degrades densities >1 mA/um by up 15%. Heating effects are reduced if the supporting insulator thinned, or shorter channel devices partial heat sinking at contacts. The transient behavior of such has thermal time constants ~30-300 ns, dominated thickness and that device capping layers (a also expected ultrathin body SOI...
The moderate band gap of black phosphorus (BP) in the range 0.3-2 eV, along a high mobility few hundred cm(2) V(-1) s(-1) provides bridge between gapless graphene and relatively low-mobility transition metal dichalcogenides. Here, we study mechanism electrical thermoelectric transport 10-30 nm thick BP devices by measurements conductance thermopower (S) with various temperatures (T) gate-electric fields. T dependences S sheet (σ□) show behaviors T(1/3) exp[-(1/T)(1/3)], respectively, where...
Abstract One-dimensional crystal growth enables the epitaxial integration of III-V compound semiconductors onto a silicon (Si) substrate despite significant lattice mismatch. Here, we report short-wavelength infrared (SWIR, 1.4–3 μm) photodetector that employs InAs nanowires (NWs) grown on Si. The wafer-scale NWs form Si without metal catalyst or pattern assistance; thus, is free metal-atom-induced contaminations and also cost-effective. NW arrays with an average height 50 μm provide...
We report on the successful terahertz emission (0.6$\sim$1 THz) that is continuous and tunable in its frequency power, by driving Josephson vortices resonance with collective standing plasma modes excited stacked Bi$_2$Sr$_2$CaCu$_2$O$_{8+x}$ intrinsic junctions. Shapiro-step detection was employed to confirm terahertz-wave emission. Our results provide a strong feasibility of developing long-sought solid-state devices.
We report transport measurements of gate-tunable Andreev bound states in a carbon nanotube quantum dot coupled to two superconducting leads. In particular, we observe clear features types Kondo ridges, which can be understood terms the interplay between effect and superconductivity. first type (type I), coupling is strong dominant. Levels display anti-crossing middle ridge. On other hand, crossing shown second II) together with 0-$\pi$ transition Josephson junction. Our scenario well only...