• Journal of Sensor Science and Technology
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• v.32 no.6
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• pp.455-461
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• 2023

We investigated the electrical characteristics of ZnO nanoparticles (NPs) with air exposure that is a widely used electron transport layer for quantum dot light-emitting diodes (QLEDs). Upon air exposure, we observed changes in the density of states (DOS) of the trap levels of ZnO NPs. In particular, with air exposure, the concentration of deep trap energy levels in ZnO NPs decreased and electron mobility significantly improved. Consequently, the air-exposed ZnO reduced leakage current by approximately one order of magnitude and enhanced the external quantum efficiency at the low driving voltage region of the QLED. In addition, based on the excellent conductivity properties, high-brightness QLEDs could be achieved.

• Journal of the Korean Vacuum Society
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• v.15 no.2
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• pp.186-193
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• 2006

In this study, we analyzed the electrical and optical properties of metalorganic chemical vapor deposition grown InGaAs/InGaAsP/InP quantum dot(QD) molecules by using photoluminescence and deep-level transient spectroscopy. From these resulte, the energy levels of the large QDs are located at deeper region from the conduction band edge of the barrier than that of the small QDs, The large QDs seem to have the energy states more than two, and these energy levels of the QD molecules are located at 0.35, 0.42, and 0.45 eV from conduction band edge under -4 V reverse bias conditions. The energy levels are closely coupled under low reverse bias, and then decoupled as the bias voltage is increased.

• Bulletin of the Korean Chemical Society
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• v.31 no.7
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• pp.2091-2093
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• 2010

• Bulletin of the Korean Chemical Society
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• v.34 no.11
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• pp.3183-3184
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• 2013

• Proceedings of the Korean Society Of Semiconductor Equipment Technology
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• 2005.09a
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• pp.137-141
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• 2005

Quantum dot(QD) 메모리용 silicon nano-particle을 corona 방전방법에 의해 상온에서 대량 발생하는 방법을 개발하였다. Silicon QD는 SiH4 가스를 코로나 방전 영역을 통과시켜 발생시켰으며, 코로나 전압은 2.75kV를 사용하였다. SiH4 몰농도 $0.33{\times}10^{-7}\;mol/l$ 일 경우 발생된 QD입자 크기는 약 10nm이며 기하학적 표준편차(geometric standard deviation)는 1.31이었다. 이 조건에서 nonvolatile quantum dot semiconductor memory (NVQDM)를 제작하였으며, 이렇게 제작된 NVQDM flat band voltage는 1.5 volt였다.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.18 no.6
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• pp.527-531
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• 2005

Fully coherent self-assembled InAs quantum dots(QDs) grown on Si (100) substrates by atmospheric pressure metalorganic chemical vapor deposition(APMOCVD) were grown and the effect of growth conditions such as growth rate and growth time on quantum dots' morphology such as densities and sizes was investigated. InAs QDs of 30 - 80 nm in diameters with densities in the range of (0.6 - 1.7) x $10^{10}\;cm^{-2}$ were achieved on Si substrates and InAs layer was changed from 2 dimensional growth to 3 dimensional one at a nominal thickness less than 0.48 ML. This is attributed to the higher ambient pressure of APMOCVD suppressing of In segregation from the 2 dimensional InAs layer. This In segregation looked to disturb the dot formation especially when the growth rate was low so that the dots became less dense and bigger as the growth rate was lower.

• Journal of the Korean Vacuum Society
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• v.18 no.5
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• pp.365-371
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• 2009

We analyzed photoluminescence (PL) and electroluminescence characteristics of various chirped quantum dot structures. Peaks in EL curves were contributed by excited states of quantum dots (QD), while those in PL curves by grounded states. Based on these characteristics, we suggested that superluminescent diodes with wide spectral bandwidth may be developed if chirped QD structures are designed to make a contribution by ground states to EL characteristics.

• Bulletin of the Korean Chemical Society
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• v.25 no.6
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• pp.934-936
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• 2004

• Journal of the Korean Magnetic Resonance Society
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• v.23 no.2
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• pp.51-55
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• 2019

Quantum dot (QD) is an emerging novel nanomaterial that has wide applicability and superior functionality with relatively low cost. Nuclear magnetic resonance (NMR) spectroscopy has been contributed to elucidate various features of QDs and to improve their overall performance. In particular, NMR spectroscopy becomes an essential analytical tool to monitor and analyze organic ligands on the QD surface. In the present mini-review, application of NMR spectroscopy as a superb methodology to appreciate organic ligands is discussed. In addition, it was recently noted that ligands exert rather greater influence on diverse features of QDs than our initial anticipation, for which contribution of NMR spectroscopy is briefly reviewed.

• 한국초전도학회:학술대회논문집
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• v.16
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• pp.18-18
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• 2006