• 한국정보디스플레이학회:학술대회논문집
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• 2008.10a
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• pp.239-242
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• 2008

We have investigated the reliability of short channel ($L=1.5{\mu}m$) p-type ELA poly-Si TFTs under hot carrier stress. Threshold voltage of short channel TFT was significantly more shifted to positive direction than that of long channel TFT under the same stress. This result may be attributed to electron trapping at the interface between poly-Si film and gate oxide layer.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09b
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• pp.718-719
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• 2006

Two different commercial aluminium powder grades have been densified by direct hot extrusion. The extrusion temperature was $425^{\circ}C$, with an extrusion ratio of 1:16. Prior to extrusion, some green compacts were pre-sintered ($500^{\circ}C$). The evolution of the extrusion load during the process and the hardness of the final products have been investigated. Additionally, microstructural characterization by X-ray diffraction (XRD), Scanning Electron Microscopy (SEM) and Electron Backscattered Diffraction (EBSD) was carried out. The obtained results evidence grain refinement. Additionally, inter-metallic precipitation, dynamic recovery and geometric dynamic recrystallization take place depending on some process variables, powder composition, heat treatment, strain $\ldots$

• Journal of the Korean Institute of Telematics and Electronics A
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• v.32A no.6
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• pp.59-66
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• 1995

The hot electron induced effective channel length modulation (${\Delta}L_{H}$) and HEIP characteristics in PMOSFET's after bidirectional stress are presented. Trapped electron charges in gate oxide and lateral field are calculated from the gate current model, and ${\Delta}L_{H}$(${\Delta}L_{HD},\;{\Delta}L_{HS}$) is calculated using trapped electron charges and lateral field. It has been found that ${\Delta}I_{d}$and ${\Delta}L_{H}$ are more affected by the stress order (Forward-Reverse of Reverse or Reverse-Forward) than the stress direction, and they vary logarithmically with the stress time. In contrast, ${\Delta}V_{t}$ and ${\Delta}V_{pt}$ are more affected by the stress direction thatn the stress order. The correlation between ${\Delta}V_{pt}$ and the stress time can be explanined as the following polynomial functin: ${\Delta}V_{pt}$=AT$^{n}$. It has also been shown that PMOSFET degradation is related with the gate current and the effects of ${\Delta}V_{pt}$ is the most significant.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.40 no.9
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• pp.638-643
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• 2003

Channel width dependence of hot-carrier effect in nMOSFET with shallow trench isolation is analyzed. $I_{sub}$- $V_{G}$ and $\Delta$ $I_{ㅇ}$ measurement data show that MOSFETs with narrow channel-width are more susceptible to the hot-carrier degradation than MOSFETs with wide channel-width. By analysing $I_{sub}$/ $I_{D}$, linear $I_{D}$- $V_{G}$ characteristics, thicker oxide-thickness at the STI edge is identified as the reason for the channel-width dependent hot-carrier degradation. Using the charge-pumping method, $N_{it}$ generation due to the drain avalanche hot-carrier (DAHC) and channel hot-electron (CHE) stress are compared. are compared.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.35D no.11
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• pp.62-69
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• 1998

The general degradation model has been applied to analyze the hot carrier induced degradation of the DC and RF characteristics of RF-nMOSFET. The degradation of cut-off frequency has been severer than the degradation of bulk MOSFET drain current. The value of the degradation rate n and the degradation parameter m for RF-nMOSFET has been equal to those for bulk MOSFET. The decrease of device degradation with the increase of fingers could be explained by the large source/drain parasitic resistance and drain saturation voltage. It has been also found that the RF performance degradation could be explained by the decrease of $g_{m}$ and $C_{gd}$ and the increase of $g_{ds}$ after stress. The degradation of the DC and RF characteristics of RF-nMOSFET could be predicted by the measurement of the substrate current.t.

• Journal of Powder Materials
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• v.24 no.2
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• pp.122-127
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• 2017

Fe-6.5 wt.% Si alloys are widely known to have excellent soft magnetic properties such as high magnetic flux density, low coercivity, and low core loss at high frequency. In this work, disc-shaped preforms are prepared by spark plasma sintering at 1223 K after inert gas atomization of Fe-6.5 wt.% Si powders. Fe-6.5 wt.% Si sheets are rolled by a powder hot-rolling process without cracking, and their microstructure and soft magnetic properties are investigated. The microstructure and magnetic properties (saturation magnetization and core loss) of the hot-rolled Fe-6.5 wt.% Si sheets are examined by scanning electron microscopy, electron backscatter diffraction, vibration sample magnetometry, and AC B-H analysis. The Fe-6.5 wt.% Si sheet rolled at a total reduction ratio of 80% exhibits good soft magnetic properties such as a saturation magnetization of 1.74 T and core loss ($W_{5/1000}$) of 30.7 W/kg. This result is caused by an increase in the electrical resistivity resulting from an increased particle boundary density and the oxide layers between the primary particle boundaries.

• Korean Journal of Materials Research
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• v.30 no.11
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• pp.595-600
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• 2020

The photovoltaic properties of perovskite solar cells (PSCs) with a carbon electrode fabricated using different annealing processes are investigated. Perovskite formation (50 ℃, 60 min) using a hot-plate and an oven is carried out on cells with a glass/fluorine doped TiO₂/TiO₂/ZrO₂/carbon structure, and the photovoltaic properties of the PSCs are analyzed using a solar simulator. The microstructures of the PSCs are characterized using an optical microscope, a field emission scanning electron microscope, and an electron probe micro-analyzer (EPMA). Photovoltaic analysis shows that the energy conversion efficiency of the samples fabricated using the hot-plate and the oven processes are 2.08% and 6.90%, respectively. Based on the microstructure of the samples and the results of the EPMA, perovskite is formed locally on the carbon electrode surface as the γ-butyrolactone (GBL) solvent evaporates and moves to the top of the carbon electrode due to heat from the bottom of the sample during the hot plate process. When the oven process is used, perovskite forms evenly inside the carbon electrode, as the GBL solvent evaporates extremely slowly because heat is supplied from all directions. The importance of the even formation of perovskite inside the carbon electrode is emphasized, and the feasibility of oven annealing is confirmed for PSCs with carbon electrodes.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.07a
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• pp.328-331
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• 2004

Hot filament 플라즈마 화학기상 증착법(HFPECVD)를 사용하여 질산화철의 농도에 따른 탄소나노튜브의 성장 특성을 관찰하기 위해 실험을 진행하였다. 암모니아($NH_3$)를 희석가스로 사용하였고, 아세틸렌($C_2H_2$)를 탄소 원료가스로 각각 사용하였다. 암모니아 가스 플라즈마를 사용하여 전처리 된 질산화철 촉매층의 SEM(Scanning Electron Microscopy) 이미지를 관찰하여 본 결과, 나노 사이즈의 촉매 그레인(grain)을 발견할 수 있었다. 그리고 탄소 나노튜브의 직경과 성장 밀도 또한 전처리 된 촉매 층에 따라 다른 양상을 보였다. TEM(Transmission Electron Microscopy)를 사용하여 탄소나노튜브를 관찰한 결과 bamboo 구조를 한 다중벽 탄소 나노튜브(MWCNT)를 관찰할 수 있었다.

• 대한방사선치료학회:학술대회논문집
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• 2005.06a
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• pp.27-32
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• 2005

Electron is used for the treatment of skin cancer, breast cancer, and head and neck cancer in clinic. Our study is performed to check the isodose distribut ion in source surface distance(SSD) and source bolus distance(SBD) setup, nipple influence to isodose distribution of electron, junctional area isodose variation of photon and electron field. Dosimetry is carried out with phantom, acryl, and film as the same condition of treatment setup. $8\%$ of isodose difference is noted with the surface distance(SSD) and source bolus distance(SBD) setup. To reduce the influence of nipple. corresponding volume of bolus should be removed. And bolus covering all the electron field reduced hot and cold spot of junctional area of photon.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2006.05a
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• pp.222-225
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• 2006

The effect of lubrication on the development of textures and Microstructure was studied by different lubricating condition during hot rolling of AA1050 aluminum alloy. Hot rolling without lubrication led to the evolution of the pronounced through-thickness texture gradients, whereas hot rolling with lubrication gave rise to the formation of uniform rolling texture in the whole thickness layer. The variation of texture and microstructure according to hot rolling condition are investigated by X-ray diffractometer (XRD) and Electron Back-Scattered Diffraction (EBSD). The experimental results were discussed base on the finite element method (FEM) simulation. FEM calculation reveals that a larger friction between roll and sheet causes the deviated strain state from a plane strain leading to the formation of shear textures in the thickness layers close to the surface.