• 한국안전학회지
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• 제31권3호
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• pp.42-46
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• 2016

In LCD Display or semiconductor manufacturing processes, the anti-static technology of glass substrates and wafers becomes one of the most difficult issues which influence the yield of the semiconductor manufacturing. In order to overcome the problems of wafer surface contamination various issues such as ionization in decompressed vacuum and inactive gas(i.e. $N_2$ gas, Ar gas, etc.) environment should be considered. Soft X ray radiation is adequate in air and $O_2$ gas at atmospheric pressure while UV radiation is effective in $N_2$ gas Ar gas and at reduced pressure. At this point of view, the "vacuum ultraviolet ray ionization" is one of the most suitable methods for static elimination. The vacuum ultraviolet can be categorized according to a short wavelength whose value is from 100nm to 200nm. this is also called as an Extreme Ultraviolet. Most of these vacuum ultraviolet is absorbed in various substances including the air in the atmosphere. It is absorbed substances become to transit or expose the electrons, then the ionization is initially activated. In this study, static eliminator based on the vacuum ultraviolet ray under the above mentioned environment was tested and the results show how the ionization performance based on vacuum ultraviolet ray can be optimized. These vacuum ultraviolet ray performs better in extreme atmosphere than an ordinary atmospheric environment. Neutralization capability, therefore, shows its maximum value at $10^{-1}{\sim}10^{-3}$ Torr pressure level, and than starts degrading as pressure is gradually reduced. Neutralization capability at this peak point is higher than that at reduced pressure about $10^4$ times on the atmospheric pressure and by about $10^3$ times on the inactive gas. The introductions of these technology make it possible to perfectly overcome problems caused by static electricity and to manufacture ULSI devices and LCD with high reliability.

• 한국진공학회지
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• 제12권4호
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• pp.275-280
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• 2003

Si(III) 표면위에 Gd$_2O_3:Eu^{3+}$ 결정성 형광체 박막을 이온화 집단체 증착방법으로 증착하여 이온선을 주입, 결정을 파괴한 후에 열처리를 통하여 결정구조를 변화시켰다. 초기 생장시의 결정성은 고에너지 전자회절 (RHEED)을 통해 확인하고, X선 회절과 적외선 분광법을 이용하여 시료의 결정구조의 변화를 관측하였다. Near Edge X-ray Absorption Fine Structure (NEXAFS)를 통해 전자구조의 변화를 확인하였다. 이러한 변화들이 발광 특성에 미치는 영향을 Photoluminescence (PL), Cathodoluminescence (CL), 그리고 Vacuum Ultraviolet (VUV) spectrum으로 알아보았다. 본 연구는 결정구조에 의해 변화된 전자구조가 형광체 박막의 발광특성에 미치는 영향을 보고한다.

• Applied Science and Convergence Technology
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• 제24권5호
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• pp.151-155
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• 2015

The interfacial electronic structure between zinc phthalocyanine (ZnPc) and aluminumdoped zinc oxide (AZO) substrates has been evaluated by ultraviolet photoemission spectroscopy and angle-dependent x-ray absorption spectroscopy to understanding the molecular orientation of a ZnPc layer on the performance of small molecule organic photovoltaics (OPVs). We find that the ZnPc tilt angle improves the ${\pi}-{\pi}$ interaction on the AZO substrate, thus leading to an improved short-circuit current in OPVs based on phthalocyanine. Furthermore, the molecular orientation-dependent energy level alignment has been analyzed in detail using ultraviolet photoemission spectroscopy. We also obtained complete energy level diagrams of ZnPc/AZO and ZnPc/indium thin oxide.

• 센서학회지
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• 제18권4호
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• pp.316-321
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• 2009

Er-doped ZnO(ZnO:Er) films were deposited onto MgO wafers by ultrasonic spray pyrolysis at 550 $^{\circ}C$ varying the concentration of Er in the deposition source from 0.5 wt% to 3.0 wt%. Annealing of the films in a vacuum was carried out to increase the intensity of ultraviolet(UV) emission from the films. The annealing temperature was between 600$^{\circ}C$ and 800$^{\circ}C$. The crystallographic properties and surface morphology of the films were investigated by X-ray diffraction(XRD)and scanning electron microscope(SEM), respectively. The properties of photoluminescence(PL) for the films were investigated by the dependence of PL spectra on the annealing temperature. X-ray photoelectron spectroscopy(XPS) was conducted to find the composition change in the films by the annealing.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
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• pp.290.1-290.1
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• 2016

Grapehen, a single atomic layer of graphite, has been in the spotlight and researched in vaious fields, because its fine mechanical, electrical properties, flexibility and transparence. Synthesis methods for large-area graphene such as chemical vaper deposition (CVD) and mechanical, chemical exfoliation have been reported. In particular, chemical exfoliation method receive attention due to low cost process. Chemical exfoliation method require reduction of graphene oxide in the process of exfoliation such as chemical reduction by strong reductant, thermal reduction on high temperature, and optical reduction via ultraviolet light exposure. Among these reduction methods, optical reduction is free from damage by strong reductant and high temperature. However, optical reduction is economically infeasible because the high cost of short-wavelength ultraviolet light sorce. In this paper, we make graphene-oxide and lanthanoid ion mixture aqueous solution which has highly optical absorbency in selective wevelength region. Sequentially, we synthesize reduced graphene oxide (RGO) using the solution and visible laser beam. Concretely, graphene oxide is made by modified hummer's method and mix with 1 ml each ultraviolet ray absorbent Gd3+ ion, Green laser absorbent Tb3+ ion, Red laser absorbent Eu3+ ion. After that, we revivify graphene oxide by laser exposure of 300 ~ 800 nm layser 1mW/cm2 +. We demonstrate reproducibility and repeatability of RGO through FT-IR, UV-VIS, Low temperature PL, SEM, XPS and electrical measurement.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2011년도 제40회 동계학술대회 초록집
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• pp.283-283
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• 2011

The n-doping effect by doping metal carbonate into an electron-injecting organic layer can improve the device performance by the balanced carrier injection because an electron ohmic contact between cathode and an electron-transporting layer, for example, a high current density, a high efficiency, a high luminance, and a low power consumption. In the study, first, we investigated an electron-ohmic property of electron-only device, which has a ITO/$Rb_2CO_3$-doped $C_{60}$/Al structure. Second, we examined the I-V-L characteristics of all-ohmic OLEDs, which are glass/ITO/$MoO_x$-doped NPB (25%, 5 nm)/NPB (63 nm)/$Alq_3$ (32 nm)/$Rb_2CO_3$-doped $C_{60}$(y%, 10 nm)/Al. The $MoO_x$doped NPB and $Rb_2CO_3$-doped fullerene layer were used as the hole-ohmic contact and electron-ohmic contact layer in all-ohmic OLEDs, respectively, Third, the electronic structure of the $Rb_2CO_3$-doped $C_{60}$-doped interfaces were investigated by analyzing photoemission properties, such as x-ray photoemission spectroscopy (XPS), Ultraviolet Photoemission spectroscopy (UPS), and Near-edge x-ray absorption fine structure (NEXAFS) spectroscopy, as a doping concentration at the interfaces of $Rb_2CO_3$-doped fullerene are changed. Finally, the correlation between the device performance in all ohmic devices and the interfacial property of the $Rb_2CO_3$-doped $C_{60}$ thin film was discussed with an energy band diagram.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2011년도 제41회 하계 정기 학술대회 초록집
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• pp.72-72
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• 2011

Surface science is intrinsically related to the performance of solar cells. In solar cells the generation and collection of charge carriers determines their efficiency. Effective transport of charge carriers across interfaces and minimization of their recombination at surfaces and interfaces is of utmost importance. Thus, the chemistry at the surfaces and interfaces of these devices must be determined, and related to their performance. In this talk we will discuss the role of two important interfaces, First, the role of surface passivation is very important in limiting the rate of carrier of recombination. Here we will combine x-ray photoelectron spectroscopy of the surface of a Si device with electrical measurements to ascertain what factors determine the quality of a solar cell passivation. In addition, the quality of the heterojunction interface in a ZnSe/CdTe solar cell affects the output voltage of this device. X-ray photoelectron spectroscopy gives some insight into the composition of the interface, while ultraviolet photoemission yields the relative energy of the two materials' valence bands at the junction, which controls the open circuit voltage of the solar cell. The relative energies of ZnSe and CdTe at the interface is directly affected by the material quality of the interface through processing.

• 대한화학회지
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• 제66권5호
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• pp.341-348
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• 2022

In this work, radio frequency magnetron sputtering was used to deposit zinc selenide thin films on p-type silicon (100) wafers and glass substrates in a high vacuum chamber. Several surface characterization instruments were implemented to study the thin films. X-ray photoelectron spectroscopy results revealed that oxidized Zn bound to Se (Zn-Se) at 1022.7 ± 0.1 eV becomes the dominant oxidized species when Se concentration exceeds 70%. Scanning electron microscopy coupled with energy dispersive spectroscopy showed that incorporating Se in Zn thin films will lead to formation of ZnSe grains on the surface. Contact angle measurements indicated that ZnSe-60 exhibited the lowest total surface free energy value of 24.94 mN/m. Lastly, ultraviolet-visible spectrophotometry and ultraviolet photoelectron spectroscopy data evinced that the energy band gap gradually increases with increasing Se concentration with ZnSe-70 having the highest work function value of 4.91 eV.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2011년도 제41회 하계 정기 학술대회 초록집
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• pp.353-353
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• 2011

Titanium dioxide is a suitable material for industrial use at present and in the future because titanium dioxide has efficient photoactivity, good stability and low cost [1]. Among the three phases (anatase, rutile, brookite) of titanium dioxide, the anatase form is particularly photocatalytically active under ultraviolet (UV) light. In fabrication of photocatalytic devices based on catalytic nanodiodes [2], it is challenging to obtain a photocatalytically active TiO2 thin film that can be prepared at low temperature (< 200$^{\circ}C$). Here, we present the synthesis of a titanium dioxide film using TiO2 nanoparticles and sol-gel methods. Titanium tetra-isopropoxide was used as the precursor and alcohol as the solvent. Titanium dioxide thin films were made using spin coating. The change of atomic structure was monitored after heating the thin film at 200$^{\circ}C$ and at 350$^{\circ}C$. The prepared samples have been characterized by X-ray diffraction (XRD), scanning electron microcopy, X-ray photoelectron spectroscopy, transmission electron microscopy, ultraviolet-visible spectroscopy (UV-vis), and ellipsometry. XRD spectra show an anatase phase at low temperature, 200$^{\circ}C$. UV-vis confirms the anatase phase band gap energy (3.2 eV) when using the photocatalyst. TEM images reveal crystallization of the titanium dioxide at 200$^{\circ}C$. We will discuss the switching behavior of the Pt /sol-gel TiO2 /Pt layers that can be a new type of resistive random-access memory.

• 한국세라믹학회지
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• 제38권9호
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• pp.817-821
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• 2001

새로운 형광체로 역스피넬 구조를 갖는 $Mg_{2-x}MN_xSnO_4$ 조성을 선정하여 고상반응에 의하여 제조하였다. $Mg_2SnO_4:Mn$의 광발광 특성이 147nm 파장의 진공 자외선 여기하에 측정되었다. Mn의 첨가에 의하여 $Mg_2SnO_4$ 형광체는 500nm 파장에 발광 중심을 가지며 매우 높은 발광강도를 나타내었다. 이것은 스피넬 구조의 산소 사면체 배위에 위치하는 Mg 자리를 치환하여 들어가는 $Mn^{2+}$ 이온의 $^4T_1$ 상태로부터 $^6A_1$ 상태로의 에너지 전이에 의한 발광으로 해석되었다. 진공 자외선 여기하에 최대의 발광강도를 나타내는 Mn 활성제의 농도는 0.25mol%이었고, 잔광시간은 10ms 이하인 것으로 조사되었다.