A5034774040- GaN-based semiconductor devices and materials
- Semiconductor materials and devices
- Silicon Carbide Semiconductor Technologies
- HVDC Systems and Fault Protection
- Advancements in Semiconductor Devices and Circuit Design
- Ga2O3 and related materials
- High-Voltage Power Transmission Systems
- Superconducting Materials and Applications
- Radio Frequency Integrated Circuit Design
- Semiconductor Quantum Structures and Devices
- Physics of Superconductivity and Magnetism
- Gas Sensing Nanomaterials and Sensors
- Integrated Circuits and Semiconductor Failure Analysis
- ZnO doping and properties
- Acoustic Wave Resonator Technologies
- Photonic and Optical Devices
- Analytical Chemistry and Sensors
- Thin-Film Transistor Technologies
- Thermal Analysis in Power Transmission
- Thermal properties of materials
- Metal and Thin Film Mechanics
- Nanowire Synthesis and Applications
- Spectroscopy and Laser Applications
- Electrical Fault Detection and Protection
- Advanced Photonic Communication Systems
Samsung (South Korea)
2000-2025
Hongik University
2016-2025
ON Semiconductor (United States)
2024
Inha University
2021
Korea Electric Power Corporation (South Korea)
2008-2020
Sungkyunkwan University
2018-2020
Kookmin University
2003-2018
Samsung Medical Center
2018
Korea Institute of Machinery and Materials
2015
Korea University
2013
Undoped AlGaN/GaN structures are used to fabricate high electron mobility transistors (HEMTs). Using the strong spontaneous and piezoelectric polarization inherent in this crystal structure a two-dimensional gas (2DEG) is induced. Three-dimensional (3-D) nonlinear thermal simulations made determine temperature rise from heat dissipation various geometries. Epitaxial growth by MBE OMVPE described, reaching mobilities of 1500 1700 cm/sup 2//Ns, respectively, For sheet density near 1/spl...
For the past decades, density of DRAM has been remarkably increased by making access transistors and capacitors smaller in size per unit area. However, shrinking devices far beyond 10 nm process node increasingly poses reliability challenges. As Flash technology made a pivotal successful innovation via 3D NAND, may also adopt vertical stacking memory cells. Vertically stacked (VS-DRAM) continues to increase bit on die increasing number layers along with reducing transistor. In this paper,...
The authors report on the effects of silicon nitride (SiN) surface passivation and high-electric field stress (hot electron stress) degradation undoped AlGaN-GaN power HFETs. Stressed devices demonstrated a decrease in drain current maximum transconductance an increase parasitic series resistance, gate leakage, subthreshold current. unpassivated showed more significant than SiN passivated devices. Gate lag phenomenon was observed from removed by passivation. However, also phenomena after...
The dependence of current slump in AlGaN/GaN HEMTs on the thickness AlGaN barrier was observed. Power measurements a 2×125×0.3 μm HEMT made Silicon Carbide (SiC) substrates with an 10 nm gave saturated output power 1.23 W/mm at 8 GHz whereas device same dimensions fabricated samples 20 2.65 frequency. RF load line clearly show reduction full channel as compared to dc and increase knee voltage voltage, effect being more pronounced thin samples. Passivation improved large signal performance...
Self-heating in AlGaN/GaN high electron mobility transistors (HEMTs) negatively impacts device performance and reliability. Under nominal operating conditions, a hot-spot the channel develops under drain side corner of gate due to concentration volumetric heat generation leading nonequilibrium carrier interactions non-Fourier conduction. These subcontinuum effects obscure identification most salient processes impacting heating. In response, we examine self-heating GaN-on-Si HEMTs via...
This report presents efforts for introducing a hybrid superconducting fault current limiter (SFCL) associated with the substation upgrade in Korea Electric Power Corporation (KEPCO) grid and points at issue on utility demands. The includes replacement of 154 kV/22.9 kV main transformers applying 22.9 kV/3 kA SFCLs to protect them. SFCL is expected meet not only general requirements, but also such local conditions as (1) small size be installed an in-house substation, (2) sustainable...
A combination of the multifrequency <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$C$</tex></formula> – Notation="TeX">$V$</tex></formula> and generation–recombination current spectroscopy is proposed for a complete extraction density states (DOS) in amorphous InGaZnO thin-film transistors (a-IGZO TFTs) over full subband-gap energy range Notation="TeX">$(E_{V}\leq E\leq E_{C})$</tex> </formula>...
The noble synthesis method for hydroxyapatite (HAp) nanoparticles was exploited using a fairly simple reaction of Ca(OH)2 and H3PO4, which does not generate residual harmful anions consequently need an additional washing process. HAp were found to yield from dicalcium phosphate dehydrate (DCPD) as the only intermediate phase, monitored by in situ observation study X-ray diffraction (XRD), Fourier transform infrared (FT-IR), 1H 31P magic-angle spinning (MAS) NMR. Furthermore, we that phase...
We have developed a high-quality <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$\hbox{SiO}_{2}$</tex></formula> deposition process using an inductively coupled plasma chemical vapor system for use as gate oxide of AlGaN/GaN-on-Si metal–oxide–semiconductor heterostructure field-effect transistor (MOSHFET) power switching applications. A breakdown field Notation="TeX">$\sim$</tex></formula> 12 MV/cm...
Daily pre-work safety training for workers is essential due to their exposure various hazardous factors. However, existing methods often fail effectively deliver information in a way that supports workers’ learning and comprehension, resulting poor job performance lack of adherence protocols. This study explores novel approach structuring by examining the cognitive characteristics relation placement order composition materials. An educational recall experiment involving 660 construction was...
Broad-band high-power cascode AlGaN/GaN high electron-mobility transistor monolithic-microwave integrated-circuit (MMIC) amplifiers with gain and power-added efficiency (PAE) have been fabricated on high-thermal conductivity SiC substrates. A cell exhibiting 5 W of power at 8 GHz a small-signal 19 dB was realized. nonuniform distributed amplifier (NDA) based this process designed, fabricated, tested, yielding saturated output 3-6 over dc-8-GHz bandwidth an associated PAE 13%-31%. broad-band...
This paper presents a detailed study of high-field effects in GaN MODFETs. Degradation DC characteristics and change flicker noise due to hot electron high-reverse current stresses Si/sub 3/N/sub 4/ passivated MODFETs have been investigated. The authors observe that during stress, trapping the barrier layer interface state creation occur. These cause positive shift V/sub t/, reduce I/sub D/, skew transfer characteristics, degrade g/sub m/. Flicker (1/f) measurements show after scaled drain...
We have investigated reliability enhancement of the fast switch (FS) by using power electronic switches such as integrated gate commutated thyristors (IGCT) in line commutation type hybrid superconducting fault current limiter (SFCL). The FS utilizes a vacuum interrupter (VI) to open and close primary line. operation highly relies upon complete breaking VI. Since resistance including arc may not be extremely high after VI opens, there non-zero VI, causing failure communication. IGCTs are...
The effect of temperature on gate degradation behavior was analyzed in Schottky-type p-GaN HEMTs under a positive voltage. TDDB measurements were conducted at various temperatures, revealing an accelerated failure rate lower temperatures. A Weibull distribution analysis employed to predict the 10-year rated voltage, showing that voltage −10 °C is significantly than 60 °C. Furthermore, derived activation energy −0.22 eV indicates intensifies colder environments. Hole accumulation occurring...
Undoped AlGaN/GaN HEMTs grown on SiC substrates have recently demonstrated record output power density of 10.7 W/mm (cw) and total 10 W at GHz (L. F. Eastman, Joint ONR/MURI Review (5/15–16, 2001), CA (USA) [1]). In this paper, we present the results reliability tests performed undoped under dc rf stress conditions. been submitted to on-wafer conditions a room temperature degradation in device performance induced by hot electron thermal effects observed.
This paper reports on the operation test of a 22.9 kV hybrid superconducting fault current limiter (SFCL) in KEPCO grid. The SFCL works at rated voltage and 630 A, respectively. There are two major objectives test: (1) long-term (2) tests for protection coordination study. lasted more than year. We experienced several times cryostat suspension due to blackouts false alarms sensor failures during operation. also carried out short circuit grid, equipped with breakers recloser. An artificial...
The Dirac delta function can be defined by the limitation of rectangular covering a unit area with decrease width rectangle to zero, and in quantum mechanics eigenvectors position operator take form function. When discussing measurement mechanics, one is prompted mathematical convention that uses wave sufficiently narrow approximate order making state physical. We argue such an approximation improper physics, because during energy transfer particle might infinitely large. continuous...
A monolithic X-band oscillator based on an AlGaN/GaN high electron mobility transistor (HEMT) has been designed, fabricated, and characterized. common-gate HEMT with 1.5 mm of gate width in conjunction inductive feedback is used to generate negative resistance. Q resonator implemented a short-circuit low-loss coplanar waveguide transmission line. The delivers 1.7 W at 9.556 GHz into 50-/spl Omega/ load when biased V/sub ds/=30 V gs/=-5 V, dc-to-RF efficiency 16%. Phase noise was estimated be...
Development and grid operation of superconducting fault current limiters (SFCLs) have been carried out in Korea Electric Power Corporation (KEPCO), as a possible measure to handle the increasing Korea. A 22.9 kV SFCL has successfully operated unmanned on distribution line Icheon Substation. It very stable throughout more than 1.5 year. Temperatures level liquid nitrogen that cools element maintained constant. Performance initial level. The was modified so it can limit within first half...
Presents investigations of a hybrid type superconducting fault current limiter (SFCL), which consists transformers and resistive switches. The secondary windings the transformer were separated into several electrically isolated circuits linked inductively with each other by mutual flux, has limiting unit YBa/sub 2/Cu/sub 3/O/sub 7/ (YBCO) stripes as switch. Simple connection in series SFCL switches tends to produce ill-timed switching because power dissipation imbalance between units. Both...
Broadband, high power cascode AlGaN/GaN HEMT MMIC amplifiers with gain and power-added efficiency (PAE) have been fabricated on high-thermal conductivity SiC substrates. A cell exhibiting 5 W of at 8 GHz a small signal 19 dB was realized. broadband amplifier using these cells in conjunction lossy-match input matching network designed, fabricated, evaluated, showing useful operating range DC-8 an output 5-7.5 PAE 20-33% respectively. nonuniform distributed (NDA) based this same process...
Although a long loop delay in an optoelectronic oscillator (OEO) is essential for achieving low-phase-noise signal, it generates narrowly spaced spurious modes that cannot be filtered out. Conventional dual-loop OEOs proposed to suppress the exhibit degraded phase-noise performance compared with single-loop because of short fiber OEOs. To overcome decrease performance, we investigated both theoretically and experimentally open-loop characteristics OEO. We found can eliminated without...
The impact of proton irradiation on the self-heating AlGaN/GaN high-electron-mobility transistors (HEMTs) was studied at an energy 1 MeV and under a fluence level 2 × 1015 cm–2. Severe degradation in electrical characteristics observed these conditions (5× reduction drain saturation current VGS = 0 V, positive shift threshold voltage by 3.1 V). Concomitantly, 80% increase device gate temperature using thermoreflectance thermal imaging technique, power dissipation 5 W/mm. One key contributing...