• Bulletin of the Korean Chemical Society
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• v.28 no.8
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• pp.1341-1345
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• 2007

The surface chemistry of D2O dosed Zircaloy-4 (Zry-4) surface followed by Ar-ion bombardment and annealing was studied by means of X-ray photoelectron spectroscopy (XPS) and Ultraviolet photoelectron spectroscopy (UPS). In the XPS study, Ar-ion bombardment caused decrease of the oxygen on the surface region of Zry-4 and therefore led to change the oxidation states of the zirconium from oxide to metallic form. In addition, oxidation states of zirconium were changed to lower oxidation states of zirconium due to depopulation of oxygen on the surface region by annealing. Up to about 787 K, the bulk oxygen diffused out to the subsurface region and after this temperature, the oxygen on the surface of Zry-4 was depopulated. UPS study showed that the valence band spectrum of the D2O exposed Zry-4 exhibited a dominant peak at around 13 eV and no clear Fermi edge was detected. After stepwise Ar+ sputtering processes, the decrease of the oxygen on the surface of Zry-4 led to suppress the dominant peak around 13 eV, the peak around 9 eV and develop a new peak of the metallic Zr 4d state (20.5-21.0 eV) at the Fermi level.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.15 no.5
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• pp.321-327
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• 2022

In this paper, a wrinkled structure was formed on the PDMS surface through UV/Ozone treatment, and the wrinkle structure formation mechanism was revealed through physicochemical characterization. A wrinkle structure was formed on the PDMS surface through UV/Ozone treatment for 30 min, and periodic wrinkle formation on the PDMS surface was confirmed by cross-sectional imaging of the scanning electron microscope. In addition, through x-ray photoelectron spectroscopy spectral analysis, it was confirmed that the silica-like-surface of SiOx on the PDMS surface was formed by UV/Ozone. The results of this study not only improve the understanding of the mechanism of wrinkle structure formation on the PDMS surface by UV/Ozone treatment, but also can be used as a basic study to adjust the amplitude and period of the wrinkle structure according to UV/Ozone irradiation conditions in the future.contact angles and the surface energies of FSAMs, it was confirmed that pretilt angles of LC molecules increased according to the alkyl chain length. High optical transparency and uniform homeotropic LC alignment characteristics of FSAMs showed the possibility of FSAMs as an LC alignment layers.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.418-418
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• 2012

We fabricated a new type of hybrid film using molecular layer deposition (MLD). The MLD is a gas phase process analogous to atomic layer deposition (ALD) and also relies on a saturated surface reaction sequentially which results in the formation of a monolayer in each sequence. In the MLD process, polydiacetylene (PDA) layers were grown by repeated sequential surface reactions of titanium tetrachloride and 2,4-hexadiyne-1,6-diol with ultraviolet (UV) polymerization under a substrate temperature of $100^{\circ}C$. Ellipsometry analysis showed a self-limiting surface reaction process and linear growth of the hybrid films. Polymerization of the hybrid films was confirmed by infrared (IR) spectroscopy and UV-Vis spectroscopy. Composition of the films was confirmed by IR spectroscopy and X-ray photoelectron (XP) spectroscopy. The titanium oxide cross-linked polydiacetylene (TiOPDA) hybrid films exhibited good thermal and mechanical stabilities.

• Korean Chemical Engineering Research
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• v.48 no.1
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• pp.98-102
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• 2010

Magnolia kobus leaf extract was used for the synthesis of bimetallic Au core-Ag shell nanoparticles. Gold seeds and silver shells were formed by first treating aqueous solution of $HAuCl_4$ and then $AgNO_3$ with the plant leaf extract as reducing agent. UV-visible spectroscopy was monitored as a function of reaction time to follow the formation of bimetallic nanoparticles. The synthesized bimetallic nanoparticles were characterized with transmission electron microscopy(TEM), energy dispersive X-ray spectroscopy(EDS), and X-ray photoelectron spectroscopy(XPS). TEM images showed that the bimetallic nanoparticles are a mixture of plate(triangles, pentagons, and hexagons) and spherical structures. The atomic Ag contents of the bimetallic Au/Ag nanoparticles determined from EDS and XPS analysis were 34 and 65 wt%, respectively, suggesting the formation of bimetallic Au core-Ag shell nanostructure. This core-shell type nanostructure is expected to have potential for application in surface enhanced Raman spectroscopy and in the sensitive detection of biomolecules.

• Bulletin of the Korean Chemical Society
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• v.33 no.2
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• pp.505-510
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• 2012

Cobalt oxide nanostructure materials have been prepared by adding several concentrations of spectator Ni ions in solution, and analyzed by electron microscopy, X-day diffraction, calorimetry/thermogravimetric analysis, UV-vis absorption, Raman, and X-ray photoelectron spectroscopy. The electron microscopy results show that the morphology of the nanostructures is dramatically altered by changing the concentration of spectator ions. The bulk XRD patterns of $350^{\circ}C$-annealed samples indicate that the structure of the cobalt oxide is all of cubic Fd-3m $Co_3O_4$, and show that the major XRD peaks shift slightly with the concentration of Ni ions. In Raman spectroscopy, we can confirm the XRD data through a more obvious change in peak position, broadness, and intensity. For the un-sputtered samples in the XPS measurement process, the XPS peaks of Co 2p and O 1s for the samples prepared without Ni ions exhibit higher binding energies than those for the sample prepared with Ni ions. Upon $Ar^+$ ion sputtering, we found $Co_3O_4$ reduces to CoO, on the basis of XPS data. Our study could be further applied to controlling morphology and surface oxidation state.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.211.1-211.1
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• 2013

We fabricate the conductive zinc oxide(ZnO) thin film using UV-enhanced atomic layer deposition. ZnO is semiconductor with a wide band gap(3.37eV) and transparent in the visible region. ZnO can be deposited with various method, such as metal organic chemical vapour deposition, magnetron sputtering and pulsed laser ablation deposition. In this experiment, ZnO thin films was deposited by atomic layer deposition using diethylzinc (DEZ) and D.I water as precursors with UV irradiation during water dosing. As a function of UV exposure time, the resistivity of ZnO thin films decreased dramatically. We were able to confirm that UV irradiation is one of the effective way to improve conductivity of ZnO thin film. The resistivity was investigated by 4 point probe. Additionally, we confirm the thin film composition is ZnO by X-ray photoelectron spectroscopy. We anticipate that this UV-enhanced ZnO thin film can be applied to electronics or photonic devices as transparent electrode.

• 한국신재생에너지학회:학술대회논문집
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• 2011.11a
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• pp.61.1-61.1
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• 2011

We report on a detailed study on gap-state distribution in thin amorphous silicon layers(a-Si:H) with film thickness between 5 nm and 20 nm c-Si wafers performed by UV excited photoelectron spectroscopy(UV-PES). We measured how the work function, the gap state density, the position of the Fermi-level and the Urbch-energy depend on the layer thickness and the doping level of the ultra thin a-Si:H(n) layer. It was found, that for phosphorous doping the position of the Fermi level saturates at $E_F-E_V$=1.47 eV. This is achieved at a gas phase concentration of 10000 ppm $PH_3$ in the $SiH_4/H_2$ mixture which was used for the PECVD deposition process. The variation of the doping level from 0 to 20000 ppm $PH_3$ addition results in an increase of the Urbach energy from 65 meV to 101 meV and in an increase of the gap state density at midgap($E_i-E_V$=0.86eV) from $3{\times}10^{18}$ to $2{\times}1019cm^{-3}eV^{-1}$.

• Carbon letters
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• v.21
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• pp.74-80
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• 2017

A highly facile and eco-friendly green synthesis of Annona squamosa (custard apple) leaf extract reduced graphene oxide (CRG) nanosheets was achieved by the reduction of graphene oxide (GO). The as-prepared CRG was characterized with X-ray diffraction (XRD), transmission electron microscope (TEM), Fourier-transform infrared spectroscopy (FT-IR), ultraviolet-visible (UV-Vis), X-ray photoelectron spectroscopy (XPS) and Raman spectroscopic techniques. Removal of oxygen containing moieties from the GO was confirmed by UV-Vis, FT-IR and XPS spectroscopic data. The XRD and Raman data further confirmed the formation of the CRG. TEM images showed the sheet structure of the synthesized CRG. These results show that the phytochemicals present in custard apple leaf extract act as excellent reducing agents. The CRG showed good dispersion in water.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.181.2-181.2
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• 2016

OLED 소자는 발광 방향에 따라 Bottom Emission 방식과 Top Emission 방식으로 나뉜다. 이 중 대면적 OLED TV 적용에 개구율이 더 높은 Top Emission방식을 선호하는 추세이다. 높은 개구율을 가진 Top Emission OLED소자를 위해서는 투명하고 전도성이 높은 캐소드가 중요하다. 본 연구에서는 Themal Evaporation 시스템을 이용하여 증착한 $SnO_2/Ag-Pd-Cu(APC)/SnO_2$ hybrid 전극의 특성을 연구하고 Oxide/Metal/Oxide(OMO) hybrid 박막의 bending mechanism을 제시하였다. base pressure는 $1{\times}10^{-6}Torr$로 고정하고 $SnO_2$ 박막은 0.34A / 0.32V, APC 박막은 0.46A / 0.40V의 power로 성막하였다. APC와 $SnO_2$의 두께를 변수로 OMO 전극을 제작하였고 그 전기적, 광학적 특성을 Hall measurement, UV/Visible spectroscopy을 이용하여 분석하고 Figure of merit 값을 바탕으로 최적 두께를 설정하였다. UPS(Ultraviolet Photoelectron Spectroscopy) 분석으로 $SnO_2/APC/SnO_2$ 전극의 일함수을 통해 투명 cathode로 쓰였을 때 $SnO_2$ 층이 buffer layer역할을 함을 확인하였다. XPS(X-ray photoelectron spectroscopy)를 이용하여 정성분석과 정량분석을 하였고 OMO hybrid 전극의 bending mechanism 연구를 위해 다양한 bending test (Inner/Outer dynamic fatigue test, twisting test, rolling test)를 진행하였다. 물리적 힘이 가해진 OMO hybrid 전극의 표면과 구조는 FE-SEM(Field Emission Scanning Electron Microscope) 분석을 통해서 확인할 수 있었다.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.178.1-178.1
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• 2014

본 연구에서는 RF스퍼터링법에 의하여 유리기판에 NiO를 40 nm만큼 증착시킨후, 30분 동안 각각 상온, $100^{\circ}C$, $200^{\circ}C$, $300^{\circ}C$, $400^{\circ}C$로 후 열처리 하였다. 박막의 전자적, 광학적 특성은 XPS (X-ray Photoelectron Spectroscopy), REELS (Reflection Electron Energy Loss Spectroscopy)와 UV-Spectrometer를 이용하여 =측정하였고, Hall Effect를 이용하여 전기적 특성을 측정하였다. XPS측정결과, $400^{\circ}C$ 후 열처리 한 NiO박막은 NiO 결합인 Ni2+가 줄어 들면서 금속 결합인 Ni0가 증가하면, 상온에서 띠틈이 4.0eV, 3.4eV로 줄어드는 것을 REELS로 확인 했다. 이 값은 UV-Spectrometer를 이용한 광학적 띠틈과 같음을 보였다. Hall Effect측정 결과 $400^{\circ}C$ 후 열처리한 샘플에서 P-type에서 N-type으로 바뀜을 보였으며, 비저항이 낮아지는 경향을 보였다. UV-Spectrometer를 이용한 광학적 특성을 측정해본 결과, 가시광선영역인 380 nm~780 nm에서의 투과율이 75%이상으로 투명전자소자로의 응용이 가능하다는 것을 보여 주었다.