• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.11 no.2
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• pp.189-194
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• 2018

Nowadays most integrated circuits are built using the bulk CMOS technology, but it has much difficulty in further reduction of the power consumption and die size. As a super low-power technology to solve such problems, the SOI technology attracts great attention recently. In this paper, the study results of the temperature dependency of the hot carrier effects in the n-channel MOSFETs fabricated on the thin SOI substrate were discussed. In spite that the devices employed the LDD structure, the hot carrier effects were more serious than expected due to the high series resistance between the channel region and the substrate contact to the ground, and were found to be less serious for the higher temperature with the more phonon scattering in the channel region, which resulted in reducing the hot electron generation.

• Journal of the Korean Institute of Telematics and Electronics
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• v.27 no.4
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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.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.11a
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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.

• Journal of the Korean Ceramic Society
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• v.22 no.4
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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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• v.3 no.1
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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.

• Electrical & Electronic Materials
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• v.16 no.9
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• pp.62.3-63
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• 2003

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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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.

• Applied Chemistry for Engineering
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• v.31 no.1
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• pp.73-83
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• 2020

As electronic devices become more advanced and smaller, one of the biggest problems to solve is the heat affecting the efficiency and lifetime of instruments. High thermal conductivity materials, in particular, metal or ceramic ones, have been used to reduce the heat generated from devices. However, due to their low mechanical properties and high weight, thermally conductive composites composed with polymers having a light-weight and good mechanical properties as a matrix and carbon materials having high thermal conductivity as a thermally conductive filler have been attracting great attention. To improve the thermal conductivity of the composites, a phonon scattering must be suppressed to move phonon effectively. In this review, we classified researches related to phonon migration and scattering inhibition of carbon/polymer composites, and discussed various methods to improve thermal conductivity.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.20 no.7
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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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• v.14 no.5
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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.