• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제45회 하계 정기학술대회 초록집
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• pp.240.2-240.2
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• 2013

The device scale of flash memory was confronted with quantum mechanical limitation. The next generation memory device will be required a break-through for the device scaling problem. Especially, graphene is one of important materials to overcome scaling and operation problem for the memory device, because ofthe high carrier mobility, the mechanicalflexibility, the one atomic layer thick and versatile chemistry. We demonstrate the hybrid memory consisted with the metal-oxide quantum dots and the mono-layered graphene which was transferred to $SiO_2$ (5 nm)/Si substrate. The 5-nm thick secondary $SiO_2$ layer was deposited on the mono-layered graphene by using ultra-high vacuum sputtering system which base pressure is about $1{\times}10^{-10}$ Torr. The $In_2O_3$ quantum dots were distributed on the secondary $SiO_2$2 layer after chemical reaction between deposited In layer and polyamic acid layer through soft baking at $125^{\circ}C$ for 30 min and curing process at $400^{\circ}C$ for 1 hr by using the furnace in $N_2$ ambient. The memory devices with the $In_2O_3$ quantum dots on graphene monolayer between $SiO_2$ thin films have demonstrated and evaluated for the application of next generation nonvolatile memory device. We will discuss the electrical properties to understating memory effect related with quantum mechanical transport between the $In_2O_3$ quantum dots and the Fermi level of graphene layer.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2012년도 춘계학술대회 논문집
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• pp.871-872
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• 2012

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2010년도 추계학술대회 논문집
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• pp.429-430
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• 2010

• Journal of Electrochemical Science and Technology
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• 제11권3호
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• pp.220-237
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• 2020

Modern electrochemical energy devices involve generation and reduction of fuel gases through electrochemical reactions of water splitting, alcohol oxidation, oxygen reduction, etc. Initially, these processes were executed in the presence of noble metal-based catalyst that showed low overpotential and high current density. However, its high cost, unavailability, corrosion and related toxicity limited its application. The search for alternative with high stability, durability, and efficiency led scientists towards carbon nanoparticles supported catalysts which has high surface area, good electrical conductivity, tunable morphology, low cost, ease of synthesis and stability. Carbon nanoparticles are classified into two groups based on morphology, one and zero dimensional particles. Carbon nanoparticles at zero dimension, denoted as carbon dots, are less used carbon support compared to other forms. However, recently carbon dots with improved electronic properties have become popular as catalyst as well as catalyst support. This review focused on the recent advances in electrocatalytic activities of carbon dots. The mechanisms of common electrocatalytic reactions and the role of the catalysts are also discussed. The review also proposed future developments and other research directions to overcome current limitations.

• 정보처리학회논문지C
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• 제11C권1호
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• pp.123-134
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• 2004

동기 망과 전송망에서의 동기클럭 성능은 망의 안정성 화보와 데이터 전송 보장 측면에서 중요한 요소이다. 그러므로 망을 설계할 때 동기망과 전송망의 동기클럭 성능을 분석하기 위하여 다양한 파라메타를 적용할 수 있고, 그리고 최상상태에서 최악상태까지 망에서 나타날 수 있는 여러 가지 입력레벨을 적용할 수 있는 시뮬레이터가 필요하다. 따라서 본 논문에서는 동기망과 전송망에서의 동기클럭 특성을 분석할 수 있는 SNCA와 TNCA를 개발하였고, 또한 개발된 시뮬레이터를 활용하여 다양한 원더생성, 노드 수, 클럭 상태 등의 입력조건에 따른 NEl, NE2, NE3 등 전송망과 DOTS1과 DOTS2 등 동기 망에서의 동기 클럭 특성과 최대 노드수 결과를 얻었다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2012년도 제42회 동계 정기 학술대회 초록집
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• pp.533-534
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• 2012

Colloidal III-V semiconductor nanocrystal quantum dots (NQDs) have attracted attention as they can be applied in various areas such as LED, solar cell, biological imaging, and so on because they have decreased ionic lattices, lager exciton diameter, and reduced toxicity compared with II-VI compounds. However, the study and application of III-V semiconductor nanocrystals is limited by difficulties in control nucleation because the molecular bonds in III-V semiconductors are highly covalent compared to II-VI compounds. There is a need for a method that provides rapid and scalable production of highly quality nanoparticles. We present a new synthetic scheme for the preparation of InP nanocrystal quantum dots using new phosphorus precursor, P(SiMe2tbu)3. InP nanocrystals from 530nm to 600nm have been synthesized via the reaction of In(Ac)3 and new phosphorus precursor in noncoordinating solvent, ODE. This opens the way for the large-scale production of high quality Cd-free nanocrystal quantum dots.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2012년도 제42회 동계 정기 학술대회 초록집
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• pp.541-541
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• 2012

InP quantum dots capped by myristic acid (InP-MA QDs) were synthesized by a typical hot injection method using MA as stablizing agent. The current density across the InP-MA QDs thin film which was fabricated by spin-coating method is about $10^{-4}A/cm^2$ at the electric field of 0.1 MV/cm from I-V measurement on a metal-insulator-metal (MIM) device. The low conductivity of the InP-MA QDs thin film is interpreted as due to the long interdistances among the dots governed by the MA molecules. Therefore, replacing the MA with thioacetic acid (TAA) by biphasic ligand exchange was conducted in order to obtain TAA capped InP QDs (InP-TAA). InP-TAA QDs were designed due to: 1) the TAA is very short molecule; 2) the thiolate groups on the surface of the InP-TAA QDs are expected to undergo condensation reaction upon thermal annealing which connects the QDs within the QD thin film through a very short linker -S-; and 3) TAA provides better passivation to the QDs both in the solution and thin film states which minimizing the effect of surface trapping states.

• 대한의생명과학회지
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• 제29권4호
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• pp.344-354
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• 2023

This study emphasizes the importance of early diagnosis and response to COVID-19, leading to the development of a rapid diagnostic kit using quantum dots. The research focuses on finely tuning bioconjugation with quantum dots to enhance the accuracy and sensitivity of COVID-19 diagnosis. We have developed a COVID-19 rapid diagnostic kit that exhibits a sensitivity more than 50 times higher than existing COVID-19 diagnostic kits. Quantum dots enable the accurate detection of COVID-19 viral antigens even at low concentrations, providing a rapid response in the early stages of infection. The COVID-19 quantum dot diagnostic kit offers quick analysis time, utilizing the quantum properties of particles to swiftly measure COVID-19 infection for immediate response and isolation measures. Additionally, this diagnostic kit allows for multiple analyses with ease, as multiple quantum dots can detect various antigens and antibodies simultaneously in a single experiment. This efficiency enhances testing, reduces sample requirements, and lowers experimental costs. The application of this diagnostic technology is anticipated in the future for early diagnosis and monitoring of other infectious diseases.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2015년도 제49회 하계 정기학술대회 초록집
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• pp.222.1-222.1
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• 2015

Recently, graphene quantum dots (GQDs) have attracted great attention due to various properties including cost-effectiveness of synthesis, low toxicity, and high photostability. Nevertheless, the origins of photoluminescence (PL) from GQDs are unclear because of extrinsic states of the impurities, disorder structures, and oxygen-functional groups. Therefore, to utilize GQDs in various applications, their optical properties generated from the extrinsic states should be understood. In this work, we have focused on the effect of oxygen-functional groups in PL of the GQDs. The GQDs with nanoscale and single layer are synthesized by employing graphite nanoparticles (GNPs) with 4 nm. The series of GQDs with different amount of oxygen-functional groups were prepared by the chain of chemical oxidation and reduction process. The fabrication of a series of graphene oxide QDs (GOQDs) with different amounts of oxygen-contents is first reported by a direct oxidation route of GNPs. In addition, for preparing a series of reduced GOQDs (rGOQDs), we employed the conventional chemical reduction to GOQDs solution and controlled the amount of reduction agents. The GOQDs and rGOQDs showed irreversible PL properties even though both routes have similar amount of oxyen-functional groups. In the case of a series of GOQDs, the PL spectrum was clearly redshifted into blue and green-yellowish color. On the other hand, the PL spectrum of rGOQDs did not change significantly. By various optical measurement such as the PL excitation, UV-vis absorbance, and time-resolved PL, we could verify that their PL mechanisms of GOQDs and rGOQDs are closely associated with different atomic structures formed by chemical oxidation and reduction. Our study provides an important insights for understanding the optical properties of GQDs affected by oxygen-functional groups. [1]

• 한국진공학회지
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• 제18권3호
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• pp.208-212
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• 2009

MBE법으로 성장된 InAs/AlAs 양자점(quantum dots; QD) 구조의 광학적 특성을 photoreflectance(PR) 이용하여 조사하였다. Wetting layer(WL) 두께에 따른 전체 장벽의 폭이 달라짐에 따라 GaAs 완충층 및 WL 신호의 세기가 변화되었다. QD 층이 식각된 시료의 상온 PR측정 결과로부터 $1.1{\sim}1.4\;eV$ 영역의 완만한 신호는 InAs QDs과 WL에 관련된 신호임을 알았다. 온도 $450{\sim}750^{\circ}C$범위에서 열처리 시켰을 때 WL층의 PR 신호가 red shift하였는데, 이는 열처리 후 InAs WL와 AlAs층 사이에 Al과 In의 내부 확산에 의해 양자점의 크기가 균일하게 재분포 되고, WL의 임계 두께가 증가하였음을 나타낸다.