• 한국정보전자통신기술학회논문지
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• 제11권2호
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• pp.189-194
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• 2018

현재 대부분의 집적회로는 bulk CMOS 기술을 사용해서 제작되고 있으나 전력 소모를 낮추고 die 크기를 줄이기에는 한계점에 도달해있다. 이러한 어려움을 획기적으로 극복할 수 있는 초저전력 기술로서 SOI CMOS 기술이 최근에 크게 각광을 받고 있다. 본 논문에서는 100 nm Thin SOI 기판 위에 제작된 n-채널 MOSFET 소자들의 열전자 효과들의 온도 의존성에 관한 연구 결과들이 논의되었다. 소자들이 LDD 구조를 갖고 있음에도 불구하고 열전자 효과들이 예상보다 더 심각한 것으로 나타났는데, 이는 채널과 기판 접지 사이의 직렬 저항이 크기 때문인 것으로 믿어졌다. 온도가 높을수록 채널에서의 phonon scattering의 증가와 함께 열전자 효과는 감소하였는데, 이는 phonon scattering의 증가는 결과적으로 열전자의 생성을 감소시켰기 때문인 것으로 판단된다.

• 대한전자공학회논문지
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• 제27권4호
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• pp.534-540
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• 1990

In this paper the characteristics of submicron gate GaAs MESFET's have been studied using a particle model which takes into account the hot-electron transport phenomena, i.e., the velocity overshoot. \ulcornervalley(<000> direction), L valley (<111>direction), X valley (<100>direction) as the GaAs conduction energy band and optical phonon, acoustic phonon, equivalent intervalley, nonequivalent intervalley scattering as the scattering models, have been considered in this simulation. And the GaAs material and the device simulation have been done by determination of the free flight time, scattering mechanism and scattering angle according to Monte-Carlo algorithm which makes use of a particle model. As a result of the particle simulation, firstly the electron distribution, the potential energy distribution and the situation of electron displacement in 0.6 \ulcorner gate length device have been obtained. Secondly, the cutoff frequency, obtained by this method, is k47GHz which is in good agreement with the calculated result of theory. And the current-voltage characteristics curve which takes account of the buffer layer effect has been obtained. Lastly it has been verified that parasitic current at the buffer layer can be analyzed using channel depth modulation.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2009년도 추계학술대회 논문집
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• pp.251-251
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• 2009

The generation of energy and the cooling of system using thermoelectric semiconductor material have been in spotlight. Thermoelectric effect increases with the decrease of the thermal conductivity. In the thermoelectric devices, thermal conductivity is related to phonon scattering. Therefore, few studies have been conducted in the thermoelectric materials dispersed nano oxide particle for increasing the phonon scattering. However, core-shell structure which nano particle disperses in solvents and then which thermoelectric materials coated on the nano oxide particles has not been reported. In this study, we selected commercial nano powder such as $Al_2O_3$. This nano particle was about 20nm and was crushed aggregate by mechanical treatment. We have developed the effect of the dispersant and the solvent. The properties of particles were evaluated by SEM, TEM, particle size analysis, and BET. Dispersion and dispersion stability were evaluated by electronic microscope and turbidity.

• 한국세라믹학회지
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• 제22권4호
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• pp.40-46
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• 1985

Thermal diffusivities of zirconia samples partially or fully stabilized by MgO and $Y_2O_3$ were measured b laser-flash method up to 140$0^{\circ}C$ The values of thermal diffusivity decreased as the contents of MgO and $Y_2O_3$ increased due to the phonon scattering effect of defect structure of cubic phase formed. The temperature dependence of thermal diffusivity showed that the thermal diffusivity values decreased due to phono-phonon scattering as the temperature increased. The difference in thermal diffusivity was observed on cooling after heating up to 140$0^{\circ}C$ for magnesia stabi-lized zirconia samples but not for yttria stabilized zirconia samples.

• The Korean Journal of Ceramics
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• 제3권1호
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• pp.29-33
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• 1997

Four diamond films were deposited by the microwave plasma assisted chemical vapor deposition method varying CH4 concentration from 2.5 to 10% in the feeding gases. Thermal conductivity was measured on these free standing films by the steady state method from 80 K to 400K. They showed higher thermal conductivity as the film deposited with lower methane concentration. One exception, 7.79% methane concentration deposited film, was observed to be the highest thermal conductivity. Phonon scattering processes were considered to analyze the thermal conductivity with the full Callaway model. The grain size and the concentration of the extended and the point defects were used as the fitting parameters. Microstructure of diamond films was investigated with the scanning electron microscopy and Raman spectroscopy.

• E2M - 전기 전자와 첨단 소재
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• 제16권9호
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• pp.62.3-63
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• 2003

• 한국진공학회:학술대회논문집
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• 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
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• pp.304.2-304.2
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• 2014

Chalcogenides (Te,Se) and pnictogens(Bi,Sb) materials have been widely investigated as thermoelectric materials. Especially, Bi2Te3 (Bismuth telluride) compound thermoelectric materials in thin film and nanowires are known to have the highest thermoelectric figure of merit ZT at room temperature. Currently, the thermoelectric material research is mostly driven in two directions: (1) enhancing the Seebeck coefficient, electrical conductivity using quantum confinement effects and (2) decreasing thermal conductivity using phonon scattering effect. Herein we demonstrated influence of annealing temperature on structural and thermoelectrical properties of Bismuth-telluride-selenide ternary compound thin film. Te-rich Bismuth-telluride-selenide ternary compound thin film prepared co-deposited by thermal evaporation techniques. After annealing treatment, co-deposited thin film was transformed amorphous phase to Bi2Te3-Bi2Te2Se1 polycrystalline thin film. In the experiment, to investigate the structural and thermoelectric characteristics of Bi2Te3-i2Te2Se1 films, we measured Rutherford Backscattering spectrometry (RBS), X-ray diffraction (XRD), Raman spectroscopy, Scanning eletron microscopy (SEM), Transmission electron microscopy (TEM), Seebeck coefficient measurement and Hall measurement. After annealing treatment, electrical conductivity and Seebeck coefficient was increased by defect states dominated by selenium vacant sites. These charged selenium vacancies behave as electron donors, resulting in carrier concentration was increased. Moreover, Thermal conductivity was significantly decreased because phonon scattering was enhanced through the grain boundary in Bi2Te3-Bi2Te2Se1 polycrystalline compound. As a result, The enhancement of thermoelectric figure-of-merit could be obtained by optimal annealing treatment.

• 공업화학
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• 제31권1호
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• pp.73-83
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• 2020

전자기기의 고도화 및 소형화에 따라, 기기의 효율 및 수명에 영향을 미치는 발열 문제를 해결하는 것은 가장 큰 해결 난제 중 하나가 되었다. 이를 해결하기 위하여 금속 및 세라믹 기반의 높은 열전도도를 가지는 재료가 많이 사용되어 왔으나, 낮은 기계적 물성 및 높은 중량으로 인해 가벼우면서도 기계적 특성이 좋은 고분자를 기지재로 사용하고 높은 열전도도를 갖는 탄소재료를 필러로 사용한 열전도성 복합재가 주목받고 있다. 열전도성 복합재의 열전도도를 향상시키기 위해서는 효과적인 포논의 이동이 이루어지도록 포논 산란이 억제되야한다. 본 논문에서는 탄소재료/고분자 복합재의 포논 이동 및 산란 억제에 관련된 연구를 분류하고, 열전도도 향상을 위하여 적용된 다양한 방법들에 대하여 논의하였다.

• 한국전기전자재료학회논문지
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• 제20권7호
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• pp.606-610
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• 2007

This paper describes the Raman scattering characteristics of polycrystalline (poly) 3C-SiC thin films, in which they were deposited on the oxidized Si substrate by APCVD method according to growth temperature. Since the phonon modes were not measured for $0.4{\mu}m$ thick 3C-SiC, $2.0{\mu}m$ thick 3C-SiC deposited on the oxidized Si at $1180^{\circ}C$, in which TO (transverse optical mode) and LO (longitudinal optical mode) phonon modes were appeared at 794.4 and $965.7cm^{-1}$, respectively. The broad FWHM (full width half maximum) can explain that the crystallinity of 3C-SiC deposited at $1180^{\circ}C$ becomes polycrystalline instead of disorder crystal. Additionally, the ratio of intensity $I_{LO}/I_{TO}{\approx}1.0$ of 3C-SiC indicates that the crystal disorder of $3C-SiC/SiO_2/Si$ is small. Compared poly $3C-SiC/SiO_2$ with $SiO_2/Si$ interfaces, $1122.6cm^{-1}$ phonon mode was measured which may belong to C-O bonding and two phonon modes, 1355.8 and $1596.8cm^{-1}$ related to D and G bands of C-C bonding in the Raman range of 200 to $2000cm^{-1}$.

• JSTS:Journal of Semiconductor Technology and Science
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• 제14권5호
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• pp.518-524
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• 2014

The substrate doping concentration dependence of strain-enhanced electron mobility in (110)/<110> nMOSFETs is investigated by using a self-consistent Schr$\ddot{o}$dinger-Poisson solver. The electron mobility model includes Coulomb, phonon, and surface roughness scattering. The calculated results show that, in contrast to (100)/<110> case, the longitudinal tensile strain-induced electron mobility enhancement on the (110)/<110> can be increased at high substrate doping concentration.