• 한국통신학회논문지
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• 제16권11호
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• pp.1179-1185
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• 1991

초박막 재산화 질화산화막을 $1050^{\circ}C-1100^{\circ}C$ 온도에서 20, 40초 동안 산소 분위기에서 램프 가열 방법의 급속 열처리 공정에 의해 형성 시켰다. 초박막의 전기적 특성은 누설전류, 항복전압, 시간종속 항복과 F-N 관통을 분석 하였다. 질화와 재산화 조건에 따른 전하포획의 의존성 즉 고전계 스트레스에 유기되는 항복전하량$(Q_{BD})$ 증가 여부와 평탄대역 전압이동$(\DeltaV_{FB})$을 연구하였다. 분석 결과에 의하면, 급속 열처리 재산화시 유전적 성질이 상당히 개선되었고, 항복전하량은 증가되었으며, 평탄대역전압은 감소 되었다.

• JSTS:Journal of Semiconductor Technology and Science
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• 제8권1호
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• pp.11-20
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• 2008

The structure of 2-bit/cell flash memory device was characterized for sub-50 nm non-volatile memory (NVM) technology. The memory cell has spacer-type storage nodes on both sidewalls in a recessed channel region, and is erased (or programmed) by using band-to-band tunneling hot-hole injection (or channel hot-electron injection). It was shown that counter channel doping near the bottom of the recessed channel is very important and can improve the $V_{th}$ margin for 2-bit/cell operation by ${\sim}2.5$ times. By controlling doping profiles of the channel doping and the counter channel doping in the recessed channel region, we could obtain the $V_{th}$ margin more than ${\sim}1.5V$. For a bit-programmed cell, reasonable bit-erasing characteristics were shown with the bias and stress pulse time condition for 2-bit/cell operation. The length effect of the spacer-type storage node is also characterized. Device which has the charge storage length of 40 nm shown better ${\Delta}V_{th}$ and $V_{th}$ margin for 2-bit/cell than those of the device with the length of 84 nm at a fixed recess depth of 100 nm. It was shown that peak of trapped charge density was observed near ${\sim}10nm$ below the source/drain junction.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 1999년도 제29회 춘계학술대회
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• pp.67-72
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• 1999

Scanning probe Microscope(SPM) such as Scanning Tunneling Microscope(STM) and Atomic Force Microscope(AFM) was shown to be the powerful tool for nano-scale characterization of material surfaces Using this technique, surface morphology of the cyclically deformed Cu or Cu-Al single crystal was observed. The surface became proportionately rough as the number of cycles increased, but after some number of cycles no further change was observed. Slip steps with the heights of 100 to 200 nm and the widths of 1000 to 2000 nm were prevailing at the stage. The slipped distance of one slip system at the surface was not uniform. and formation of the extrusions or intrusions was assumed to occur such place. By comparing the morphological change caused by crystallographic orientation, strain amplitude, number of cycles or stacking fault energy, some interesting results which help to clarify the basic mechanism of fatigue damage were obtained. Furthermore, applicability of the scanning tunneling microscopy to fatigue damage is discussed.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2000년도 하계학술대회 논문집
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• pp.460-463
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• 2000

The current-voltage characteristics of the sandwich system at different annealing temperatures and different bias voltages have been studied. In order to prepare the Al/V$O_X$/Al sandwich devices structure, thin films of vanadium oxide(V$O_X$) was deposited by r.f. magnetron sputtering from $V_2$$O_5$ target in 10% gas mixture of argon and oxygen, and annealed during lhour at different temperatures in vacuum. Crystall structure, surface morphology, and thickness of films were characterized through XRD, SEM and I-V characteristics were measured by electrometer. The films prepared below 20$0^{\circ}C$ were amorphous, and those prepared above 300 $^{\circ}C$were polycrystalline. At low fields electron injected to conduction band of vanadium oxide and formed space charge, current was limited by trap. Conduction mechanism at mid fields due to Schottky emission, while at high fields it changed to Fowler-Nordheim tunneling effects.

• Journal of Electrochemical Science and Technology
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• 제11권4호
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• pp.330-335
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• 2020

Silicon surface nanostructures, which can be easily prepared by electrochemical etching, have attracted considerable attention because of its useful physical properties that facilitate application in diverse fields. In this work, electrochemical and electrochemical-scanning tunneling microscopic (EC-STM) techniques were employed to study the evolution of surface morphology during the electrochemical etching of Si(111)-H in a fluoride solution. The results exhibited that silicon oxide of the Si(111) surface was entirely stripped and then the surface became hydrogen terminated, atomically flat, and anisotropic in the fluoride solution during chemical etching. At the potential more negative than the flat band one, the surface had a tendency to be eroded very slowly, whereas the steps of the terrace were not only etched quickly but the triangular pits also deepened on anodic potentials. These results provided information on the conditions required for the preparation of porous nanostructures on the Si(111) surface, which may be applicable for sensor (or device) preparation (Nanotechnology and Functional Materials for Engineers, Elsevier 2017, pp. 67-91).

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제45회 하계 정기학술대회 초록집
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• pp.132.2-132.2
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• 2013

Electrons in graphene make ballistic transport with very high mobility (${\sim}2{\times}105 $cm2V-1s-1), which holds promises for applications in fast electronic devices. However, such expectations have been hampered by the semi-metallicity or zero bandgap of graphene, which makes it impossible to completely turn off graphene transistor devices. Here, we report the observations of local bandgap modulations in Moir$\acute{e}$ patterned graphene on metal substrates using scanning tunneling microscopy and spectroscopy. The Moir$\acute{e}$ patterned graphene was made by combinations of self-assembly processes, and they showed additional electronic states that could be interpreted as sub-band states. Our experimental observations could be explained with orbital transitions of carbon atoms from sp2 to sp3, as supported by our density functional theory calculation results. Our findings will add new poweful components for device applications.

• 대한토목학회논문집
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• 제9권3호
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• pp.143-151
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• 1989

본 연구에서는 소성변형 이론에 근거한 무라야마의 침하 산정식에 탄성변형을 반영시켜 사질토층의 터널 굴착에 따른 지반침하를 보다 간편하고 정확하게 예측할 수 있는 식을 제안하였다. 국내외 터널현장의 계측자료들의 분석결과로부터, 사질토지반의 침하는 지반의 체적변화와 밀접한 관계를 갖고있어 터널의 단순한 기하학적 제원만으로는 해석이 불가능하다는 사실을 밝혔으며, 제안식의 구성요소인 전단대 폭, t값이 현장조건에서는 무라야마의 실험실 관측치보다 2~6배 정도 큰 값으로 나타남도 밝혔다. 본 제안식의 타당성을 검증하기 위하여 현장 실측결과와 무라야마 해석결과 및 탄소성 유한요소 해석결과 등과의 비교 분석을 수행하였으며, 그 결과 본 제안식에 의한 계산치는 탄소성 해석결과 및 실측치 등과 매우 근사한 값을 나타내며, 무라야마 방법은 실제 터널현장의 지반 침하량을 과소 평가함을 알 수 있었다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1999년도 춘계학술대회 논문집
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• pp.263-266
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• 1999

Electrolunlinescent devices based on conjugated polymer emitting materials have been much attracted possible applications for multicolor flat panel display, since the conjugated polymers have a small band gap emitting obtained at a low driving voltage. In this paper, we fabricated the single layer EL device using poly(3-hexylthiophene) as emitting material Electroluminescence(EL) and I-V-L characteristics of indium-tin-oxide[ITO]P3HT/AI device with a various thickness were investigated. It was demonstrate that the I-V characteristics depend, not the voltage but the electric- field strength, The current is dependent on the electric filed and not on the applied voltage, indicating that the carriers are injected by a tunneling process. In the device, the barrier to hole injection is only 0.5eV and the barrier to electron injection is 1.5eV.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 추계학술대회 논문집 전기물성,응용부문
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• pp.139-141
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• 2005

It is possble to study charge transfer property which is caused by height variation because we can see the organic materials barrier height and STM tip by organic materials energy band gap. Here, we investigated the negative differential resistance(NDR) and charge transfer property of self-assembled 4,4-Di(ethynylphenyl)-2'-nitro-1-(thioacetyl)benzene, which has been well known as a conducting molecule. Self-assembly monolayers(SAMs) were prepared on Au(111), which had been thermally deposited onto pre-treatment($H_{2}SO_{4}:H_{2}O_{2}$=3:1) Si. The Au substrate was exposed to a 1 mM/l solution of 1-dodecanethiol in ethanol for 24 hours to form a monolayer. After thorough rinsing the sample, it was exposed to a $0.1{\mu}M/1$ solution of 4,4-Di(ethynylphenyl)-2'-nitro-1-(thioacetyl)benzene in dimethylformamide(DMF) for 30 min and kept in the dark during immersion to avoid photo-oxidation. After the assembly, the samples were removed from the solutions, rinsed thoroughly with methanol, acetone, and $CH_{2}Cl_{2}$, and finally blown dry with $N_2$. Under these conditions, we measured electrical properties of self-assembly monolayers(SAMs) using ultra high vacuum scanning tunneling microscopy(UHV-STM). The applied voltages were from -1.50 V to -1.20 V with 298 K temperature. The vacuum condition is $6{\times}10^{-8}$ Torr. As a result, we found that NDR and charge transfer property by a little change of height when the voltage is applied between STM tip and electrode.

• 한국재료학회지
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• 제2권4호
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• pp.285-292
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• 1992

Si(100) 웨이퍼를 사용하여 RTP 장비에서 $O_2$와 $N_2$O 분위기에서 8nm의 oxynitride를 제조 하였다. 기존의 로(furnace) 열산화막과 비교해서 oxynitride는 I-V, TDDB 특성이 우수하였고, flat-band voltage shift도 적었으며 $BF_2이온$ 주입에 의한 붕소 투과 억제 특성도 우수하다. 유전상수는 oxynitride가 열산화막에 비해서 크다. Oxynitride는 순수한 Si$O_2$유사하게 V 〉${\varphi}_0$ 구간에서 Fowler-Nordheim 터널링 특성을 나타낸다. SIMS, AES, 그리고 XPS 분석 결과 질소 pile-up이 Si$O_2$/Si 계면에서 나타나고, 이것은 oxynitride 산화막 특성 향상과 깊은 관련이 있다.