A5034250677- Semiconductor Quantum Structures and Devices
- Organic Electronics and Photovoltaics
- Conducting polymers and applications
- Luminescence and Fluorescent Materials
- Organic Light-Emitting Diodes Research
- Spectroscopy and Quantum Chemical Studies
- Advanced Semiconductor Detectors and Materials
- Organoboron and organosilicon chemistry
- Scientific Measurement and Uncertainty Evaluation
- Synthesis and characterization of novel inorganic/organometallic compounds
- Advanced Electrical Measurement Techniques
- Optical Network Technologies
- Electromagnetic Compatibility and Measurements
- GaN-based semiconductor devices and materials
- Strong Light-Matter Interactions
- Spectroscopy and Laser Applications
- Optical properties and cooling technologies in crystalline materials
- Advanced Thermodynamics and Statistical Mechanics
- Porphyrin and Phthalocyanine Chemistry
- Photochromic and Fluorescence Chemistry
- nanoparticles nucleation surface interactions
- Terahertz technology and applications
- Microwave and Dielectric Measurement Techniques
- Thin-Film Transistor Technologies
- Nanowire Synthesis and Applications
Korea Research Institute of Standards and Science
1995-2024
Korea Institute of Science & Technology Information
2008
Seoul National University
1996-1997
Chungnam National University
1992
We have studied the anti-Stokes photoluminescence (ASPL) of a type-II ${\mathrm{Al}}_{x}{\mathrm{Ga}}_{1\ensuremath{-}x}{\mathrm{A}\mathrm{s}\ensuremath{-}\mathrm{G}\mathrm{a}\mathrm{I}\mathrm{n}\mathrm{P}}_{2}$ heterojunction. found that ASPL can appear in both layers adjacent to heterojunction when excitation photon energy is higher than below-band-gap (BBG) luminescence. The intensity ${\mathrm{GaInP}}_{2}$-related shows an almost linear dependence on intensity. Time-resolved experiments...
We discuss a few examples of cases in which the widely used mean-field approaches to alloys and alloy superlattices may not give complete solutions. These include anomalously large Stokes anti-Stokes real space-charge transfer over thick barriers spatial extent optical phonons superlattices, have remained unsolved or controversial. argue, both theoretically experimentally, that fully account for inhomogeneities, partial ordering, disorder effects as well proper understanding coupled...
Time resolved photoluminescence (PL) characteristics of a SiN cap disordered GaAs/AlGaAs multiple quantum well (MQW) structure exhibit decrease in carrier lifetime conjunction with an increase disordering (QWD) as the capping layer thickness is increased. The attributed to enhanced trapping due defects introduced during dielectric and relaxation momentum conservation radiative recombination by QWD. Potential applications these effects on high speed optical devices such laser diodes (LD’s)...
A type I InAs(Sb)/InAsPSb strain engineered multiple quantum wells light emitting diodes system has been demonstrated. Tensile InAsPSb barriers with a high degree of band offset (∆EC = 116–123 meV, ∆EV 193–250 meV) were used to compensate for the compressive InAs(Sb) wells. The structure was grown on n+-InAsxP1−x metamorphic buffer relaxation (98%), low surface roughness (0.69 nm), and dislocation density. Through careful engineering design, reaches 0.57%–1.52% without relaxation....
The piston guide and magnet assembly for the KRISS watt balance were tested. velocity of was controlled within 4×10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-3</sup> at 2 mm s xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> using a linear motor encoder feedback. which consists two permanent rings closed yokes fabricated. B-field air gap 25 measured Hall probe. uniformity 5×10 xmlns:xlink="http://www.w3.org/1999/xlink">-4</sup> over...
In the present study, we introduce a wideband calibration method of electric field strength sensors by using gigahertz transverse electromagnetic (GTEM) cell and reference sensor. A preliminary comparison shows good agreement between proposed other ones. Another measurement result will be presented at conference.
Abstract Light emitting properties of poly(2-fluoro-l,4-phenylenevinylene) (PFPV) were investigated by using steady-state and time-resolved photoluminescence spectroscopies, EL spectra current-voltage characteristics. PFPV exhibited a red-shifted structureless emission with higher PL quantum efficiency in comparison PPV. The experiments revealed that the shorter wavelength is attributable to free excitons longer self-trapped excitons. I-V characteristics polymers showed typical diode...
The authors report on the syntheses of a series fully conjugated porphyrin pentamers in which units are arranged cruciform fashion. molecules display strong Q absorption their UV/Vis spectra.
Recombination characteristics of n-AlxGa1−xAs/n-In0.5Ga0.5P type-II band line-up heterostructures are investigated using time-integrated and time-resolved photoluminescence (PL) measurements. It is observed that the decay time AlxGa1−xAs luminescence depends on whether or not excitation photon energy,ℏωe, larger than In0.5Ga0.5Pband-gap energy, Eg,InGaP. If ℏωe&gt;Eg,InGaP, photoexcited holes in In0.5Ga0.5P layers found to be equilibrium within about 0.4 ns. The interface-related...
Abstract PPV was sensitized by ethyl viologen which is well known as a good electron acceptor, to achieve efficient ionization of the excitons created photoexcitation PPV. PPV/ethyl-viologen composites were successfully prepared from PPV-precursor and ethyl-viologen because both compounds could be soluble in polar solvents such methanol, water etc. We observed dramatic decrease photoluminescence efficiency composite film compared with film. This attributed photoinduced transfer occurred this...
KRISS Kibble balance was successfully set up and weighing moving mode experiments were performed. The repeatability of experiment, ( <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">B</i> · xmlns:xlink="http://www.w3.org/1999/xlink">l</i> ) <sub xmlns:xlink="http://www.w3.org/1999/xlink">stat</sub> , is about 3 ×10 <sup xmlns:xlink="http://www.w3.org/1999/xlink">-7</sup> . In mode, xmlns:xlink="http://www.w3.org/1999/xlink">dyn</sub> also evaluated...
The quantum efficiency of the blended polymeric system consisting poly[2-methoxy-5-(2-ethylhexyloxy)-l,4-phenylenevinylene] (MEH-PPV) and conjugated-nonconjugated multi-block copolymer (CNMBC), poly[l,3-propane-dioxy-1,4-phenylene-1,2-ethylene-(2,5-bis(trimethylsilyl)-1,4 -phenylene)-1,2-ethylene-1,4-phenylene] (DSiPV) is several times higher than that constituent polymers, which explained in terms Forster energy transfer theory. But ultrafast photoexcitation dynamics MEH-PPV polymer DSiPV...
Dimethyl or diphenyl branched conjugated polycarbosilane oligomers in solutions, including poly[[1,4-bis(thiophenyl)buta-1,3-diyne]-alt-(dimethylsilane)], poly[[1,4-bis(thiophenyl)buta-1,3-diyne]-alt-(diphenylsilane)], poly[[1,4-bis(phenyl)buta-1,3-diyne]-alt-(dimethylsilane)], and poly[[1,4-bis(phenyl)buta-1,3-diyne]-alt-(diphenylsilane)], were investigated by steady-state picosecond time-resolved spectroscopies to elucidate the effect of silicon-atom introduction into π-conjugated...
We develop a theoretical model to analyze nonequilibrium optical- (LO-) phonon population by Raman scattering in GaAs/${\mathrm{Al}}_{\mathit{x}}$${\mathrm{Ga}}_{1\mathrm{\ensuremath{-}}\mathit{x}}$As quantum wells. With the assumption of bulklike hot-electron relaxation, effect LO-phonon confinement on optical-phonon (NOP) is isolated. Our analysis shows that decrease spatial extent or coherence length LO phonons reflected NOP. This because contributions from large q wave vectors with small...
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