• 한국전기전자재료학회논문지
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• 제21권6호
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• pp.575-579
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• 2008

Al-doped p-type ZnO films were fabricated on n-Si (100) and homo-buffer layers in pure oxygen at $450^{\circ}C$ of by RF magnetron sputtering. Target was ZnO ceramic mixed with 2 wt% $Al_2O_3$. XRD spectra show that the Al-doped ZnO thin films have ZnO crystal structure and homo-buffer layers are beneficial to Al-doped ZnO films to grow along c-axis. Hall Effect experiments with Van der Pauw configuration show that p-type carrier concentrations are ranged from $1.66{\times}10^{16}$ to $4.04{\times}10^{18}\;cm^{-3}$, mobilities from 0.194 to $2.3\;cm^2V^{-1}s^{-1}$ and resistivities from 7.97 to $18.4\;{\Omega}cm$. p-type sample has density of $5.40\;cm^{-3}$ which is smaller than theoretically calculated value of $5.67\;cm^{-3}$. XPS spectra show that Ols has O-O and Zn-O structures and Al2p has only Al-O structure. P-ZnO:Al/n-ZnO:Al junctions were fabricated by magnetron sputtering. V-I curves show that the p-n junctions have rectifying characteristics.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2007년도 추계학술대회 논문집
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• pp.408-409
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• 2007

Al-doped p-type ZnO films were fabricated on n-Si (100) and homo-buffer layers in pure oxygen at $450^{\circ}C$ by RF magnetron sputtering. Target was ZnO ceramic mixed with 2wt% $Al_2O_3$. XRD spectra show that the Al-doped ZnO thin films have ZnO crystal structure and homo-buffer layers are beneficial to Al-doped ZnO films to grow along c-axis. Hall Effect experiments with Van der Pauw configuration show that p-type carrier concentrations are ranged from $1.66{\times}10^{16}\;to\;4.04{\times}10^{18}cm^{-3}$, mobilities from 0.194 to $2.3cm^2V^{-1}s^{-1}$ and resistivities from 7.97 to $18.4{\Omega}cm$. P-type sample has density of $5.40cm^{-3}$ which is smaller than theoretically calculated value of $5.67cm^{-3}$. XPS spectra show that O1s has O-O and Zn-O structures and A12p has only Al-O structure. P-ZnO:Al/n-ZnO:Al junctions were fabricated by magnetron sputtering. V-I curves show that the p-n junctions have rectifying characteristics.

• Electronic Materials Letters
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• 제14권6호
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• pp.755-765
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• 2018

In situ nitrogen doped hard carbon nanotubes (NHCNT) were fabricated by pyrolyzing tubular nitrogen doped conjugated microporous polymer. KOH activated NHCNT (K-NHCNT) were also prepared to improve their porous structure. XRD, SEM, TEM, EDS, XPS, Raman spectra, $N_2$ adsorption-desorption, galvanostatic charging-discharge, cyclic voltammetry and EIS were used to characterize the structure and performance of NHCNT and K-NHCNT. XRD and Raman spectra reveal K-NHCNT own a more disorder carbon. SEM indicate that the diameters of K-NHCNT are smaller than that of NHCNT. TEM and EDS further indicate that K-NHCNT are hollow carbon nanotubes with nitrogen uniformly distributed. $N_2$ adsorption-desorption analysis reveals that K-NHCNT have an ultra high specific surface area of $1787.37m^2g^{-1}$, which is much larger than that of NHCNT ($531.98m^2g^{-1}$). K-NHCNT delivers a high reversible capacity of $918mAh\;g^{-1}$ at $0.6A\;g^{-1}$. Even after 350 times cycling, the capacity of K-NHCNT cycled after 350 cycles at $0.6A\;g^{-1}$ is still as high as $591.6mAh\;g^{-1}$. Such outstanding electrochemical performance of the K-NHCNT are clearly attributed by its superior characters, which have great advantages over those commercial available carbon nanotubes ($200-450mAh\;g^{-1}$) not only for its desired electrochemical performance but also for its easily and scaling-up preparation.

• 한국전기전자재료학회논문지
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• 제35권3호
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• pp.292-296
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• 2022

(La_0.5Nd_0.2Sr_0.3)MnO₃ specimens were prepared by a solid-state reaction. In all specimens, X-ray diffraction patterns of an orthorhombic structure were shown. The fracture surfaces of (La_0.5Nd_0.2Sr_0.3)MnO₃ specimens showed a transgranular fracture pattern be possibly due to La ions (0.122 nm) as a perovskite A-site dopant substituting for Nd ions (0.115 nm) having a small ionic radius. The full-width at half maximum (FWHM) of the Mn 2p XPS spectra showed a value greater than that [8] of the single valence state, which is believed to be due to the overlapping of Mn²⁺, Mn³⁺, and Mn⁴⁺ ions. The dependence of Mn 2p spectra on the Mn³⁺/Mn⁴⁺ ratio according to sintering time was not observed. Electrical resistivity resulted in the minimum value of 100.7 Ω-cm for the specimen sintered for 9 hours. All specimens show a typical negative temperature coefficient of resistance (NTCR) characteristics. In the 9-hour sintered specimen, TCR, activation energy, and B25/65-value were -1.24%/℃, 0.19 eV, and 2,445 K, respectively.

• 한국진공학회지
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• 제6권3호
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• pp.200-205
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• 1997

고분자 Polyethylene(PE) film 표면을 1keV의 산소 이온 빔만을 사용하여, 또는 산 소 분위기에서 1keV의 아르곤 이온 빔으로 조사하는 이온보조반응(ion assisted reaction)법 을 이용하여 개질을 하였다. 개질된 polyethylene 표면의 친수성(wettability)과 표면 에너지 를 측정하기 위해 접촉각 측정기(contact angle micrometer)를 사용하였으며, 개질된 표면의 화학적 변화를 측정하기 위해 x-ray photoelectron spectroscopy(XPS)를 이용하였다. 표면 개질을 위한 이온 조사량은 $1\times 10^{14}-1\times\;ions/\textrm{cm}^2$, 산소 가스는 0~4sccm(ml/min.)까지 변화 시켰다. 산소 이온 빔만으로 조사 후 polyethylene 표면과 물과의 접촉각은 $95^{\circ}$에서 최대 $62^{\circ}$까지 변화하였으며, 산소를 4sccm(ml/min.) 주입하면서 아르곤 이온 빔으로 조사 하면 물과의 접촉각이 최대 $28^{\circ}$까지 감소하였으며, 이때 이온 조사량은 $1\times 10^{17}-1\times\;ions/\textrm{cm}^2$이 었다. 또한 polyethylene을 산소 이온 빔으로만 표면 개질시 표면 에너지는 작은 증가를 보 였으며, 산소 분위기에서 아르곤 이온 빔으로 표면 개질 하였을 때에는 표면 에너지가 2배 에 가까운 증가를 하였다. 이와 같은 표면의 친수성과 표면 에너지의 증가는 이온보조반응 법에 의해 polyethylene의 표면을 산소 분위기에서 아르곤 이온 빔으로 조사한 시료의 XPS 의 spectra결과로 보아 PE의 표면에 C-O 또는 C=O와 관련된 결합의 증가로 인한 친수성 작용기가 poluethlene표면에 형성되었기 때문이라고 사료된다.

• 한국자기학회지
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• 제18권1호
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• pp.19-23
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• 2008

Sol-gel 법을 이용하여 $V_xFe_{3-x}O_4$(x=0.0, 0.15, 0.5, 1.0) 박막 시료을 만들어 V 치환에 따른 $Fe_3O_4$의 결정구조적 특성을 X-ray diffraction(XRD)과 X-ray photoelectron spectroscopy(XPS)로 조사하였다. 특히 Fe 이온의 전하상태와 거동에 관하여 강력하게 조사할 수 있는 conversion electron $M\"{o}ssbauer$(CEMS) 분광법을 이용하여 양이온들의 거동과 초미세 자기적 성질을 분석하였다. X-선 회절실험의 결과 $V_xFe_{3-x}O_4(X{\leq}1.0)$ 박막 시료들의 결정구조는 스피넬구조로서 V 조성값 증가에 따라 격자상수값이 약간 증가함을 보여준다. XPS 조사에서 x값 증가에 따라 처음에는 $V^{3+}$ 이온이 B-자리의 $Fe^{3+}$ 이온을 주로 치환하고 x값이 더 커지면서 $V^{2+}$ 이온의 $Fe^{2+}$ 치환도 발생되는 것으로 나타났다. 이것은 격자상수값이 증가하는 분석 결과를 잘 설명하여 준다. CEMS 측정 결과에서 나타난 양이온 거동은 주로 B-자리의 $Fe^{3+}$ 이온에 대한 $V^{3+}$ 이온 치환이 나타나고, V 조성값이 더 크게 증가함에 따라 $V^{2+}$ 이온의 $Fe^{2+}$ 치환도 발생됨을 알 수 있었다. 그리고 이것은 V 치환이 Fe 이온 주위의 국부적 전하분포와 대칭성의 변화를 가져와 초미세 자기적 성질의 변화를 초래함을 의미한다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1995년도 추계학술대회 논문집
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• pp.217-220
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• 1995

By substituting Cd$\^$2+/ into both A-site and B-site in PNN-PZ-PT ternary perovskite material, it is possible to determine the effects of the substitution site of Cd$\^$2+/ on sintering behavior. Sintering was performed in the temperature range from 1000$^{\circ}C$ to 1300$^{\circ}C$. The substitution site of Cd$\^$2+/ is identified by XPS spectra. Although Cd$\^$2+/ is substituted into both A-site and B-site in PNN-PZ-PT, Cd$\^$2+/ prefers A-site to B-site. The density is influenced by substitution site of Cd$\^$2+/. If Cd$\^$2+/ replaces Pv$\^$2+/, weight gain is observed during sinterig process. On the contrary, if Cd$\^$2+/ replaces Ni$\^$2+/, weight loss is promoted during sintering. From these weight changes, it is believed that Cd$\^$2+/ changes the bonding strength between B-site cation and oxygen of octahedron in perovskite structure. The changes of lattice parameters as a function of Cd$\^$2+/ content were consistent with those of the bonding strength. The densities of A-site-doped compositions were higher than those of B-site-doped composition.

• Bulletin of the Korean Chemical Society
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• 제32권8호
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• pp.2531-2536
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• 2011

Ethanol is a prototype molecule used in probing catalytic reactivity of oxide catalysts such as $TiO_2$. In the present study, we adsorbed ethanol on $TiO_2$(001) at room temperature (RT) and the corresponding bonding state of ethanol was systematically studied by x-ray photoemission spectroscopy (XPS) using synchrotron radiation. Especially, we compared $TiO_2$(001) surfaces prepared in ultra-high vacuum (UHV) with different surface treatments such as $Ar^+$-sputtering and oxidation with molecular $O_2$, respectively. We find that the saturation coverage of ethanol at RT varies depending on the amount of reduced surface defects (e.g., $Ti^{3+}$) which are introduced by $Ar^+$-sputtering. We also find that the oxidized $TiO_2$(001) surface has other type of surface defects (not related to Ti 3d state) which can dissociate ethanol for further reaction above 600 K. Our C 1s core level spectra indicate clearly resolved features for the two chemically distinct carbon atoms from ethanol adsorbed on $TiO_2$(001), showing the adsorption of ethanol proceeds without C-C bond dissociation. No other C 1s feature for a possible oxidized intermediate was observed up to the substrate temperature of 650 K.

• Journal of Information Display
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• 제6권1호
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• pp.28-32
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• 2005

The electronic structures of Al/RbF/tris-(8-hydroxyquinoline)aluminium ($Alq_3$) and $Al/CaF_2/Alq_3$interfaces were investigated using x-ray photoelectron spectroscopy (XPS) and ultraviolet photoelectron spectroscopy (UPS). For both systems, the UPS showed a significant valence band shift following the deposition of the thin fluoride layers on $Alq_3$. However, the formation of gap state in valence region and the extra peak N 1s core level spectra showed different trends, suggesting that the alkali fluoride and alkali-earth fluoride interlayer have different reaction mechanisms at the interface between Al cathode and $Alq_3$. In addition, the deposition of Al has considerably less effect on the valence band shift compared to the deposition of both RbF and $CaF_2$. These results suggest that the charge transfer across the interface and the resulting gap state formation may have lesser effect on the enhancement of organic light-emitting device performance than the observed valence band shift, which is thought to lower the electron injection barrier.

• 한국전기전자재료학회논문지
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• 제15권11호
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• pp.953-957
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• 2002

Single crystal 3C-SiC (cubic silicon carbide) thin-films were deposited on Si(100) wafer up to the thickness of 4.3 ${\mu}{\textrm}{m}$ by APCVD (atmospheric pressure chemical vapor deposition) method using HMDS (hexamethyildisilane; ｛CH$_{3}$｝$_{6}$ Si$_{2}$) at 135$0^{\circ}C$. The HMDS flow rate was 0.5 sccm and the carrier gas flow rate was 2.5 slm. The HMDS flow rate was important to get a mirror-like crystal surface. The growth rate of the 3C-SiC film was 4.3 ${\mu}{\textrm}{m}$/hr. The 3C-SiC epitaxial film grown on Si(100) wafer was characterized by XRD (X-ray diffraction), AFM (atomic force microscopy), RHEED (reflection high energy electron diffraction), XPS (X-ray photoelecron spectroscopy), and Raman scattering, respectively. Two distinct phonon modes of TO (transverse optical) near 796 $cm^{-1}$ / and LO (longitudinal optical) near 974$\pm$1 $cm^{-1}$ / of 3C-SiC were observed by Raman scattering measurement. The heteroepitaxially grown film was identified as the single crystal 3C-SiC phase by XRD spectra (2$\theta$=41.5。).).