• 전기전자학회논문지
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• 제25권4호
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• pp.770-773
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• 2021

본 논문에서는 tapering과 ferroelectric(HfO₂)구조가 적용된 3D NAND flash memory의 프로그램 이후 시간경과에 따른 retention특징을 분석했다. Nitride에 trap된 전자는 시간이 지남에 따라 lateral charge migration이 발생한다. 프로그램 이후 시간이 지남에 따라 trap된 전자가 tapering에 의해 두꺼워진 채널 쪽으로 lateral charge migration이 더 많이 발생하는 것을 확인했다. 또한 Oxide-Nitride-Ferroelectric (ONF) 구조는 polarization에 의해 lateral charge migration이 완화되기 때문에 기존 Oxide-Nitride-Oxide (ONO) 구조 보다 문턱전압(V_th)의 변화량이 줄어든다.

• 반도체디스플레이기술학회지
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• 제18권4호
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• pp.138-142
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• 2019

As the NAND flash memory goes to 3D vertical Silicon-Oxide-Nitride-Oxide-Silicon (SONOS) structure, the lateral charge migration can be critical in the reliability performance. Even more, with miniaturization of flash memory cell device, just a little movement of trapped charge can cause reliability problems. In this paper, we propose a method of predicting the trapped charge profile in the retention mode. Charge diffusivity in the charge trapping layer (Si₃N₄) was extracted experimentally, and the effect on the trapped charge profile was demonstrated by the simulation and experiment.

• 반도체디스플레이기술학회지
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• 제18권2호
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• pp.82-86
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• 2019

The reliability of 3D NAND flash memory cell is affected by the charge migration which can be divided into the vertical migration and the lateral migration. To clarify the difference of two migrations, the activation energy of the charge loss is extracted and compared in a conventional square device pattern and a new test pattern where the perimeter of the gate is exaggerated but the area is same. The charge loss is larger in the suggested test pattern and the activation energy is extracted to be 0.058 eV while the activation energy is 0.28 eV in the square pattern.

• 전기전자학회논문지
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• 제26권2호
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• pp.329-332
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• 2022

본 논문에서는 ferroelectric(HfO₂)구조가 적용된 3D NAND flash memory의 parameter에 따른 lateral charge migration의 retention과 V_th를 분석하였다. P_s가 클수록 Program 시 ferroelectric에서 가능한 최대 polarization이 크기 때문에 초기 V_th는 P_s 25µC/cm² 보다 P_s 70µC/cm²에서 약 1.04V차이로 커진다. 또한 Program 이후 trap된 전자는 시간이 지남에 따라서 lateral charge migration이 발생한다. Program 이후 gate에 전압을 가하지 않고 ferroelectric은 polarization을 유지하기 때문에 P_s와 크게 관계없이 P_r이 클수록 polarization이 커지고 lateral charge migration에 의한 ∆V_th는 P_r 5µC/cm² 보다 P_r 50µC/cm²에서 약 1.54V차이로 작아진다.

• Computers and Concrete
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• 제13권1호
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• pp.117-133
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• 2014

This study presents a rapid method for determining the steady state migration coefficient of concrete by measuring the electric current. This study determines the steady state chloride migration coefficient using the accelerated chloride migration test (ACMT). There are two stages to obtain the chloride migration coefficient. The first stage, the steady-state condition was obtained from the initial electric current at the beginning of ACMT. The second stage, the average electrical current in the steady state condition was used to determine the steady state chloride migration coefficient. The chloride migration coefficient can be determined from the average steady state current to avoid sampling and analyzing chlorides during the ACMT.

• 한국세라믹학회지
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• 제53권3호
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• pp.312-316
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• 2016

The energetics of defects in the presence of domain walls in $LiNbO_3$ are characterized using density-functional theory calculations. Domain walls show stronger interactions with antisite defects than with interstitial defects or vacancies. As a result, antisite defects act as a strong pinning center for the domain wall in $LiNbO_3$. Analysis of migration behavior of the antisite defects across the domain wall shows that the migration barrier of the antisite defects is significantly high, such that the migration of antisite defects across the domain wall is energetically not preferable. However, further study on excess electrons shows that the migration barrier of antisite defects can be lowered by changing the charge states of the antisite defects. So, excess electrons can enhance the migration of antisite defects and thus facilitate domain wall movement by weakening the pinning effect.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2008년도 추계학술대회 논문집 전기설비전문위원
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• pp.233-234
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• 2008

We observed internal space charge behavior for two types of epoxy composites under dc electric fields to investigate the influence of water at high temperature. In the case of glass/epoxy specimen, homocharge is observed at water-treated specimen, and spatial oscillations become clearer in the water-treated specimens. Electric field in the vicinity of the electrodes shows the injection of homocharge. In aramid/epoxy specimens, heterocharge is observed at water-treated specimens, i.e. negative charge accumulates near the anode, while positive charge accumulates near the cathode. Electric field is enhanced just before each electrode. In order to further examine the mechanism of space charge formation, we have developed a new system that allows in situ space charge observation during ion migration tests at high temperature and high humidity. Using this in situ system.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2008년도 제39회 하계학술대회
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• pp.2307-2308
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• 2008

We observed internal space charge behavior for two types of epoxy composites under dc electric fields to investigate the influence of water at high temperature. In the case of glass/epoxy specimen, homocharge is observed at water-treated specimen, and spatial oscillations become clearer in the water-treated specimens. Electric field in the vicinity of the electrodes shows the injection of homocharge. In aramid/epoxy specimens, heterocharge is observed at water-treated specimens, i.e. negative charge accumulates near the anode, while positive charge accumulates near the cathode. Electric field is enhanced just before each electrode. In order to further examine the mechanism of space charge formation, we have developed a new system that allows in situ space charge observation during ion migration tests at high temperature and high humidity. Using this in situ system.

• Bulletin of the Korean Chemical Society
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• 제21권5호
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• pp.477-482
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• 2000

Phenyl group migration within protonated 1,2-diphenyl hydrazines has been studied theoretically using the semi-empirical AM1 method. This reaction proceeds through a 3-membered cyclic transition state and requires high activation energy. In the reactant, there was no resonance stabilization for the moving Z-ring, however, hammett $p_Z^+$ values are large due to the direct involvement of the Z-ring inthe reaction, and the development of a negative charge on the reaction center gives them a posifive value. In the case of the non-moving ring, $p_Y^+$ values are small and negative owing to the smaller positive charge increase in the reaction center. The cross-interaction constant, $p_YZ^+$, was obtained from the activation enthalpies, using the multipe linear regression methdo, and the interaction between two substituents, Y and Z, is examined.

• Nuclear Engineering and Technology
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• 제52권10호
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• pp.2285-2289
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• 2020

Protactinium contamination is a mayor issue in the thorium fuel cycle. We investigate, in this work, the consequences of Pa incorporation in vacancy defects and interstitials in Th, ThC and ThN. We calculate charge transfers and lattice distortions due to these incorporations as well as migration paths and energies involved in the diffusion of Pa.