• 한국결정학회지
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• 제14권2호
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• pp.62-66
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• 2003

VGF법을 사용하여 CuBr₂ dopant가 첨가된 Bi₂Te/sub 2.55/Se/sub 0.45/ 열전재료를 제조하였다. 이 방법을 사용하여 일방향으로 성장된 Bi₂Te/sub 2.55/Se/sub 0.45/ 잉곳의 제조가 가능하였으며 XRD 분석 결과 우선성장 방향이 (0 1 5)면임이 밝혀졌다. 본 실험을 통하여 제조한 열전재료의 Seebeck 계수와 전기전도도를 373∼523 K 범위에서 측정하였다.

• 한국전기전자재료학회논문지
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• 제32권5호
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• pp.376-381
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• 2019

In this work, we evaluated the structural, electrical and optical properties of $Ge_8Sb_2Te_{11}$ and Cu-doped $Ge_8Sb_2Te_{11}$ thin films prepared by rf-magnetron reactive sputtering. The 200-nm-thick deposited films were annealed in a range of $100{\sim}400^{\circ}C$ using a furnace in an $N_2$ atmosphere. The amorphous-to-crystalline phase changes of the thin films were investigated by X-ray diffraction (XRD), UV-Vis-IR spectrophotometry, a 4-point probe, and a source meter. A one-step phase transformation from amorphous to face-centered-cubic (fcc) and an increase of the crystallization temperature ($T_c$) was observed in the Cu-doped film, which indicates an enhanced thermal stability in the amorphous state. The difference in the optical energy band gap ($E_{op}$) between the amorphous and crystalline phases was relatively large, approximately 0.38~0.41 eV, which is beneficial for reducing the noise in the memory devices. The sheet resistance($R_s$) of the amorphous phase in the Cu-doped film was about 1.5 orders larger than that in undoped film. A large $R_s$ in the amorphous phase will reduce the programming current in the memory device. An increase of threshold voltage ($V_{th}$) was seen in the Cu-doped film, which implied a high thermal efficiency. This suggests that the Cu-doped $Ge_8Sb_2Te_{11}$ thin film is a good candidate for PRAM.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2004년도 추계학술대회 논문집 Vol.17
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• pp.167-170
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• 2004

The stochiometric mix of evaporating materials for the $CuGaT_2$ single crystal thin films was prepared from horizontal furnance. Using extrapolation method of X-ray diffraction patterns for the $CuGaTe_2$ polycrystal, it was found tetragonal structure whose lattice constant $a_0$ and $c_0$ were 6.025 ${\AA}$ and 11.931 ${\AA}$, respectively. To obtain the single crystal thin films, $CuGaTe_2$ mixed crystal was deposited on throughly etched semi-insulator GaAs(100) substrate by the Hot Wall Epitaxy (HWE) system. The source and substrate temperature were $670^{\circ}C$ and $410^{\circ}C$ respectively, and the thickness of the single crystal thin films is $2.1{\mu}m$. The crystalline structure of single crystal thin films was investigated by the photoluminescence and double crystal X-ray diffraction (DCXD). From the photocurrent spectrum by illumination of perpendicular light on the c - axis of the $CuGaTe_2$ single crystal thin film, we have found that the values of spin orbit coupling ${\Delta}s.o$ and the crystal field splitting ${\Delta}cr$ were $0.079\underline{1}eV$ and $0.246\underline{3}eV$ at 10 K, respectively. From the PL spectra at 10K, the peaks corresponding to free bound excitons and D-A pair and a broad emission band due to SA is identified. The binding energy of the free excitons are determined to be $0.047\underline{0}eV$ and the dissipation energy of the donor-bound exciton and acceptor-bound exciton to be $0.049\underline{0}eV$, $0.055\underline{8}eV$, respectively.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2004년도 하계학술대회 논문집 Vol.5 No.2
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• pp.842-844
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• 2004

Ternary tellurite glassy systems $(CuO-V_2O_5-TeO_2)$ have been synthesised using tellurium oxide as a network former and copper oxide as network modifier. The addition of a transition-matal oxide makes them electric or mixed electric-ionic conductors, which are of potential interest as cathode materials for solid-state batteries. This glass-ceramics crystallized from the $CuO-V_2O_5-TeO_2$ system are particularly interesting, because they exhibit high conductivity ( up to $6.03{\times}10^{-3}S/cm$) at room temperature. the glass samples were prepared by quenching the melt on the copper plate and the glass-ceramics were heat-treated at crystallizing temperature determined from differential thermal analysis (DTA). The electric D.C conductivity result have been analyzed in terms of a small polaron-hopping model.

• Applied Science and Convergence Technology
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• 제23권6호
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• pp.392-397
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• 2014

CuO nanotubes are synthesized using $TeO_2$ nanorod templates for application to $H_2S$ gas sensors. $TeO_2$ nanorod templates were synthesized by using the VS method through thermal evaporation. Scanning electron microscopy, transmission electron microscopy and X-ray diffraction showed that the synthesized nanotubes were monoclinic-structured polycrystalline CuO with diameter and wall thickness of approximately 100~300 nm and 5~10 nm, respectively. The CuO nanotube sensor showed responses of 136~325% for the $H_2S$ concentration of 0.1~5 ppm at room temperature. These response values are approximately twice as high as that of the CuO nanowire sensor for the same concentrations of $H_2S$ gas. Along with the investigation of the performance of the sensors, the mechanisms of $H_2S$ gas sensing of the CuO nanotubes are also discussed in this study.

• 한국결정학회지
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• 제8권1호
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• pp.48-58
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• 1997

[ $CuInTe_2$ ] 다결정은 수평전기로에서 합성하고, $CuInTe_2$ 단결정은 수직 Bridgman 방법으로 성장시켰다. $CuInTe_2$ 단결정의 c축에 수직 및 평행한 시료의 광전도도와 광발광특성을 293K에서 20 K의 온도영역에서 측정하였다. 측정된 광전류 봉우리로부터 구한 c축에 수직 및 평행한 시료의 에너지 띠 간격은 상온에서 각각 0.948 eV와 0.952 eV였다. 광전류 봉우리와 광발광 봉우리의 에너지차는 포논에너지이며 상온에서 c축에 수직 및 평행한 시료의 에너지차는 각각 22.12 meV와 21.4 meV였다. 또한 광전류 스펙트럼으로부터 시료의 spin-orbit 상호작용과 결정장 상호작용에 의한 가전자대의 갈라짐 ${\Delta}cr$과 ${\Delta}so$는 각각 0.046, 0.014 eV였다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2003년도 추계학술대회 논문집 Vol.16
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• pp.156-159
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• 2003

The stochiometric mixture of evaporating materials for the $CuInTe_2$ single crystal thin films was prepared from horizontal furnace. To obtain the single crystal thin films, $CuInTe_2$ mixed crystal was deposited on throughly etched GaAs(100) by the Hot Wall Epitaxy(HWE) system. The source and substrate temperature were $610^{\circ}C\;and\;450^{\circ}C$ respectively, and the growth rate of the single crystal thin films was about $0.5{\mu}m/h$. The crystalline structure of single crystal thin films was investigated by the double crystal X-ray diffraction(DCXD). From the photocurrent spectra, we have found that values of spin orbit coupling ${\Delta}So$ and crystal field splitting ${\Delta}Cr$ ware $0.283{\underline{3}}eV\;and\;0.120{\underline{0}}eV$, respectively.

• Progress in Superconductivity
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• 제1권1호
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• pp.36-41
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• 1999

Methods for mode identification and accurate measurements of the unloaded Q ($Q_0$) of a dielectric-loaded $TE_{01{\delta}}$ mode cavity resonator with HTS endplates are proposed. A resonator with a sapphire rod and $YBa_2Cu_3O_{7-x}$(YBCO) endplates was prepared and its microwave properties were studied at temperatures above 30 K. The $TE_{01{\delta}}$ mode $Q_0$ of the resonator, designed to work as a tunable resonator with variations in the gap distance (s) between the sapphire rod and the top YBCO, was more than 1000000 at s = 0 mm and at 30 K with the resonant frequency of 19.56 GHz. The $TE_{01{\delta}}$ mode $Q_0$ decreases as s increases for s < 2 mm until mode couplings between the $TE_{01{\delta}}$ mode and other modes appeared at s = 2 mm. Significant dependence of the $TE_{01{\delta}}$ mode $Q_0$ on the input and output coupling constants was also observed. Applications of the open-ended $TE_{01{\delta}}$ mode cavity resonator for a tunable resonator with a very high Q as well as a characterization tool for the surface resistance measurements of HTS films are described.

• Journal of Electrochemical Science and Technology
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• 제6권3호
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• pp.106-110
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• 2015

This study investigates Cu(II) complexes of cyclam, propylene cross-bridged cyclam (PCB-cyclam), and propylene cross-bridged cyclam diacetate (PCB-TE2A) as homogeneous electrocatalysts for CO₂ reduction in comparison with Ni(II)-cyclam. It is found that Cu(II)-cyclam can catalyze CO₂ reduction at the potential close to its thermodynamic value (0.75 V vs. Ag/AgCl) in tris-HCl buffer (pH 8.45) on a glassy carbon electrode. Cu(II)-cyclam, however, suffers from severe demetalation due to the insufficient stability of Cu(I)-cyclam. Cu(II)-PCB-cyclam and Cu(II)-PCB-TE2A are revealed to exhibit much less demetalation behavior, but poor CO₂ reduction activities as well. The inferior electrocatalytic ability of Cu(II)-PCB-cyclam is ascribed to its redox potential that is too high for CO₂ reduction, and that of Cu(II)-PCB-TE2A to the steric hindrance preventing facile contact with CO₂ molecules. This study suggests that in addition to the redox potential and chemical stability, the stereochemical aspect has to be considered in designing efficient electrocatalysts for CO₂ reduction.

• 한국초전도학회:학술대회논문집
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• 한국초전도학회 1999년도 High Temperature Superconductivity Vol.IX
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• pp.75-82
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• 1999

TE$_{01\;{\delta}}$ mode Cavity Resonators with a low loss dielectric rod and YBa$_2Cu_3O_{7-{\delta}}$ (YBCO) endplates were prepared and their microwave properties were studied at temperatures above 30 K. Both sapphire and rutile were used as the dielectrics. The TE$_{01\;{\delta}}$ mode Q$_0$ of the resonator, designed to work as a tunable resonator with variations in the gap distance (s) between the dielectric rod and the top YBCO, was more than 1000000 at s = 0 mm and at 30 K and .the resonant frequency of 19.56GHz when a sapphire rod was used for the dielectric. The TE$_2Cu_3O_{7-{\delta}}$ mode resonant frequency (f$_0$) appeared to decrease as the temperature is raised. Meanwhile, the temperature dependence of the TE$_2Cu_3O_{7-{\delta}}$ mode f$_0$ of the rutile-loaded resonator appeared different with f$_0$ increasing according to the temperature and Q$_0$ more than 300000 at 30 K and f$_0$ = 8.56 CHz. Comparisons were made between the microwave properties of the sapphire-loaded and the rutile-loaded resonators. Also, applications of the TE$_2Cu_3O_{7-{\delta}}$ mode cavity resonator for a tunable resonator with a very high Q$_0$ as · well as a characterization tool for surface resistance measurements of HTS films are described.