• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.362.1-362.1
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• 2016

InAs nanowires were synthesized by a vapor-liquid-solid method with InAs powder. The composition and crystalline structure of nanowires were confirmed by energy-dispersive spectroscopy (EDS) and high resolution transmission electron microscopy (HRTEM), respectively. The thermal conduction of nanowires was investigated by the optical method using Raman spectroscopy: i.e., the local temperature on nanowire was determined by laser heating. As temperature increased, the Raman peaks are shifted to low frequency and broadened. The temperature dependent Raman scattering experiments was realized on InAs nanowires with different percentages of zinc-blende and wurtzite structure. The temperature dependence on the nanowire structure has been successfully obtained: the phonon scattering was more increased in InAs heretostructure nanowires, compared to the InAs nanowires with homostructure. The result strongly suggests that the thermal conduction can be effectively controlled by ordered interface without any decrease in electrical conduction.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1995.11a
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• pp.126-130
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• 1995

$CdS_{1-x}Te_{1-x}$ polycrystalline thin films were fabricated from CdS and CdTe powder by co-evaporation method at $10^{-6}$ Torr. The Optimum evaporation condition was substrate temperature $T_{s}$=$150^{\circ}C$, evaporation time t=30 min. XRD spectrums indicated that the crystal structure chanced from zinc blonde (x$\leq$0.22) to wurtzite (x$\geq$0.96) through mixed structure (0.22$\leq$0.74) as composition value x increase to CdS. Conductive type was n-type by hot point probe method. van der Pauw method was not applicable for x<0,5 due to high hall voltages, Electrical resistivity and Hall carrier mobility were decreased as x increase, while Hall carrier concentration was increased. The optical bandgap of $CdS_{1-x}Te_{1-x}$ polycrystalline thin films measure d at R.T. had quardratic form and the bowing parameter was fitted as 1.98eV for theoretical value of 2.0eV. I-V characteristics of In/CdTe/$CdS_{x}Te_{1-x}$Au Schottky diodes showed that CdS-rich one had better forward characteristics than CdTe-rich one.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.21 no.12
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• pp.1576-1585
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• 1997

The microexplosive combustion of a slurry droplet was investigated experimentally. The microexplosion has been approximately considered to be caused by pressure build-up in the shell and to be promoted by heterogeneous nucleation of liquid carrier, which is due to the suppression of evaporation and subsequent superheating of liquid carrier. To closely investigate the pressure build-up and the heterogeneous nucleation, the experiments were conducted in an electric combustor, of which temperature was controllable (400 K-900 K). And the effects of two aligned droplets on the interactive combustion and microexplosion were found in a hot post region of a flat flame burner. Transient internal temperature distributions for slurry droplets were measured. And the shell formation and the microexplosion of suspended A1/JP-8 and Al/n-heptane slurry droplets were examined with various surfactant concentrations (0.5-5 wt%) and solid loadings (10-50 wt.%). The microexplosion time of binary array of droplets was found to be less than that of the isolated droplet due to radiative interaction between droplets.

• Current Applied Physics
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• v.18 no.12
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• pp.1534-1539
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• 2018

SnSe single crystal showed a high thermoelectric zT of 2.6 at 923 K mainly due to an extremely low thermal conductivity $0.23W\;m^{-1}\;K^{-1}$. It has anisotropic crystal structure resulting in deterioration of thermoelectric performance in polycrystalline SnSe, providing a low zT of 0.6 and 0.8 for Ag and Na-doped SnSe, respectively. Here, we presented the thermoelectric properties on the K-doped $K_xSn_{1-x}Se$ (x = 0, 0.1, 0.3, 0.5, 1.5, and 2.0%) polycrystals, synthesized by a high-temperature melting and hot-press sintering with annealing process. The K-doping in SnSe efficiently enhances the hole carrier concentration without significant degradation of carrier mobility. We find that there exist widespread Se-rich precipitates, inducing strong phonon scattering and thus resulting in a very low thermal conductivity. Due to low thermal conductivity and moderate power factor, the $K_{0.001}Sn_{0.999}Se$ sample shows an exceptionally high zT of 1.11 at 823 K which is significantly enhanced value in polycrystalline compounds.

• Bulletin of the Korean Chemical Society
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• v.32 no.5
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• pp.1587-1592
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• 2011

The aim of the present study was to improve the solubility and bioavailability of a poorly water-soluble drug in human body, using a solid dispersion technique (hot melt extrusion). The solid dispersion was prepared by cooling the hot melt of the drug in the carrier (Vitamin E TPGS and PVP). The dissolution rate of formulation 1 from a novel formulation prepared by solid dispersion technique was equal to release of formulation 6 (40% of eprosartan mesylate is in contrast to teveten$^{(R)}$) within 60 min (Table 1). The oral bioavailability of new eprosartan mesylate tablet having vitamin E TPGS and PVP K29 was tested on rats and dogs. Of the absorption enhancer and polymer tested, vitamin E TPGS and PVP K29, resulted in the greatest increases of AUC in animals (about 2.5-fold increase in rat and dog). When eprosartan mesylate was mixed with the absorption enhancer and polymer in a ratio of 2.94:2:1, vitamin E TPGS and PVP K29 improved eprosartan mesylate bioavailability significantly compared with the conventional immediate release (IR) tablet Teveten$^{(R)}$ (formulation 7). These results show that solid dispersion using vitamin E TPGS and PVP K29 is a promising approach for developing eprosartan mesylate drug products.

• Transactions on Electrical and Electronic Materials
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• v.12 no.3
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• pp.93-97
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• 2011

In this paper, we discuss design considerations for an n-channel metal-oxide-semiconductor field-effect transistor (MOSFET) with a lateral asymmetric channel (LAC) doping profile. We employed a 0.35 ${\mu}M$ standard complementary MOSFET process for fabrication of the devices. The gates to the LAC doping overlap lengths were 0.5, 1.0, and 1.5 ${\mu}M$. The drain current ($I_{ON}$), transconductance ($g_m$), substrate current ($I_{SUB}$), drain to source leakage current ($I_{OFF}$), and channel-hot-electron (CHE) reliability characteristics were taken into account for optimum device design. The LAC devices with shorter overlap lengths demonstrated improved $I_{ON}$ and $g_m$ characteristics. On the other hand, the LAC devices with longer overlap lengths demonstrated improved CHE degradation and $I_{OFF}$ characteristics.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.353-353
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• 2012

채널 도핑이 다른 비대칭 구조를 갖는 NMOSFET의 게이트 전압에 따른 Drain saturation current (IDSAT), maximum transconductance (GM) 및 threshold voltage (VT)와 같은 다양한 변수를 측정하였고 DAHC (Drain avalanche hot carriers) 스트레스에 따른 특성을 추출하였다. 전기적 특성은 반도체 파라미터 분석기를 사용하여 Probe system에서 진행되었다. 문턱전압은 Normal channel dopoing의 경우 0.67 V, High channel doping의 경우 0.74 V로 High channel doping된 소자가 상대적으로 높은 문턱전압을 보였다. Swing의 경우 Normal channel doping의 경우 87 mV/decade, high channel doping의 경우 92 mV/decade으로 High channel doping된 소자가 더 높은 Swing값을 보였다. 스트레스 인가 후 두 소자 모두 문턱전압이 증가하고 ON-current가 감소하였다. High channel doing된 소자의 경우 Normal channel doping된 소자보다 문턱전압의 증가율과 Current 감소율 측면 모두 스트레스에 더 민감하게 반응하였다. 문턱전압이 서로 다른 비대칭 NMOSFET의 핫 캐리어 특성을 비교, 분석결과 스트레스 인가에 따라 채널 도핑이 높아질수록 드레인과 게이트간의 더 높은 전계가 생겨 게이트 산화막과 Si/SiO2 계면의 손상이 더 발생하였다. 따라서 채널 도핑이 상대적으로 높은 트랜지스터가 핫 캐리어에 의한 계면 트랩 생성 비율이 더 높다는 것을 알 수 있다.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.18 no.11
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• pp.996-1000
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• 2005

Experimental results are presented for the degradation of 3 nm-thick gate oxide $(SiO_2)$ under both Negative-bias Temperature Instability (NBTI) and Hot-carrier-induced (HCI) stresses using P and NMOSFETS, The devices are annealed with hydrogen or deuterium gas at high-pressure $(1\~5\;atm.)$ to introduce higher concentration in the gate oxide. Both interface trap and oxide bulk trap are found to dominate the reliability of gate oxide during electrical stress. The degradation mechanism depends on the condition of electrical stress that could change the location of damage area in the gate oxide. It was found the trap generation in the gate oxide film is mainly related to the breakage of Si-H bonds in the interface or the bulk area. We suggest that deuterium bonds in $SiO_2$ film are effective in suppressing the generation of traps related to the energetic hot carriers.

• Journal of Integrative Natural Science
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• v.3 no.1
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• pp.54-59
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• 2010

A stoichiometric mixture of evaporating materials for $ZnIn_2Se_4$ single crystal thin films was prepared from horizontal electric furnace. To obtain the single crystal thin films, $ZnIn_2Se_4$ mixed crystal was deposited on thoroughly etched semi-insulating GaAs(100) substrate by the Hot Wall Epitaxy (HWE) system. The source and substrate temperatures were $630^{\circ}C$ and $400^{\circ}C$, respectively. The crystalline structure of the single crystal thin films was investigated by the photoluminescence and double crystal X-ray diffraction (DCXD). The carrier density and mobility of $ZnIn_2Se_4$ single crystal thin films measured from Hall effect by van der Pauw method are $9.41{\times}10^{16}cm^{-3}$ and $292cm^2/v{\cdot}s$ at 293 K, respectively. The temperature dependence of the energy band gap of the $ZnIn_2Se_4$ obtained from the absorption spectra was well described by the Varshni's relation, $Eg(T)=1.8622eV-(5.23{\times}10^{-4}eV/K)T^2/(T+775.5K)$.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09a
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• pp.480-481
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• 2006

The n-type $(95%Bi_2Te_3-5%Bi_2Se_3)$ compound was newly fabricated by gas atomization and hot extrusion, which is considered to be a mass production technique of this alloy. The effect of powder size on thermoelectric properties of 0.04% $SbI_3$ doped $95%Bi_2Te_3-5%Bi_2Se_3$ alloy were investigated. Seebeck coefficient $({\alpha})$ and Electrical resistivity $(\rho)$ increased with increasing powder size due to the decrease in carrier concentration by oxygen content. With increasing powder size, the compressive strength of $95%Bi_2Te_3-5%Bi_2Se_3$ alloy was increased due to the relative high density. The compound with ${\sim}300\;{\mu}m$ size shows the highest power factor among the four different powder sizes. The rapidly solidified and hot extruded compound using $200[\sim}300{\mu}m$ powder size shows the highest compressive strength.