• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.398.1-398.1
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• 2014

The $Cu_2ZnSnSe_4$ (CZTSe) thin films solar cell is one of the next generation candidates for photovoltaic materials as the absorber of thin film solar cells because it has optimal bandgap (Eg=1.0eV) and high absorption coefficient of $10^4cm^{-1}$ in the visible length region. More importantly, CZTSe consists of abundant and non-toxic elements, so researches on CZTSe thin film solar cells have been increasing significantly in recent years. CZTSe thin film has very similar structure and properties with the CIGS thin film by substituting In with Zn and Ga with Sn. In this study, As-deposited CZTSe thin films have been deposited onto soda lime glass (SLG) substrates at different deposition condition using Pulsed Laser Deposition (PLD) technique without post-annealing process. The effects of deposition conditions (deposition time, deposition temperature) onto the structural, compositional and optical properties of CZTSe thin films have been investigated, without experiencing selenization process. The XRD pattern shows that quaternary CZTSe films with a stannite single phase. The existence of (112), (204), (312), (008), (316) peaks indicates all films grew and crystallized as a stannite-type structure, which is in a good agreement with the diffraction pattern of CZTSe single crystal. All the films were observed to be polycrystalline in nature with a high (112) predominant orientation at $2{\theta}{\sim}26.8^{\circ}$. The carrier concentration, mobility, resistivity and optical band gap of CZTSe thin films depending on the deposition conditions. Average energy band gap of the CZTSe thin films is about 1.3 eV.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.439-440
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• 2008

Indium Zinc Tin Oxide (IZTO) thin films for transparent thin film transistor (TTFT) were deposited on glass substrate at room temperature by facing targets sputtering (FTS). The FTS system was designed to array two targets facing each other and forms the high- density plasma between. Two different kinds of targets were installed on FTS system. One is ITO ($In_2O_3$ 90wt.%, $SnO_2$ 10wt.%), the other is IZO($In_2O_3$ 90wt%, ZnO 10wt%). The conductive and optical properties of IZTO thin film is determined depending on variation of DC power and working pressure. Therefore, IZTO thin films were prepared with different DC power and working pressure. As-deposited IZTO thin films were investigated by a UV/VIS spectrometer, an X-ray diffractometer (XRD), a scanning electron microscopy (SEM), a Hall Effect measurement system. As a result, all IZTO thin films deposited on glass substrate showed over 80% of transmittance in visible range (400~800 nm) at $O_2$ gas flow rate. We could obtain IZTO thin films with the lowest resistivity $5.67\times10^{-4}$ [$\Omega{\cdot}cm$] at $O_2$ gas flow rate 0.4 [sccm).

• Journal of Conservation Science
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• v.29 no.4
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• pp.355-366
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• 2013

Diverse scientific analyses, including microstructure, ICP-AES, SEM-EDS, and P-XRF(Bench Top type and Gun type), were carried out on 6 bronze artefacts which handed from generation to generation. Also, we attempted to study applicability for authenticity of the bronze artefacts using scientific analyses based on the specific element. The results of ICP-AES analysis showed that the bronze were formed from an alloy of Cu, Sn, Pb with trace elements such as Ag, As, Co, Fe, but there were not Zn found. The result of P-XRF are 10~25% lower in Cu and 10~20% higher in Sn than that of ICP-AES. This is because of destannification that the compound of $SnO_2$ are present on the surface. The results of SEM-EDS represented that there is lead segregation. It was difficult to study applicability for authenticity of bronze artefact according to the microstructures and chemical components of the bronze artefacts. Therefore, as bronze artefacts have shown different corrosion materials depending on the buried environment and conserving environment, identifying the authenticity would be possible on the basis of the additional researches on the corrosion and comparative research of ancient art.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.11a
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• pp.108-108
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• 2009

ITO에 사용되는 주된 재료인 인듐의 bixbyite 구조는 TCOs의 전기적 특성에서 매우 중요한 것으로 알려져 있다. 때문에 인듐의 Bixbyite구조를 유지하면서 인듐의 사용량을 줄이기 위해 최적의 Solubility limit에 관해 연구하였다. 이를 위해 In2O3-ZnO-SnO2의 삼성분계 기본 조성에 두가지 물질을 추가로 첨가하여 첨가량에 따른 Solubility limit을 연구하였다. Solubility limit의 측정을 위해 X-ray Diffractometer(XRD)를 사용하였으며, 첨가 원소의 양이 증가할수록 TCOs target의 Latice parameter값은 작아졌다, SEM을 통한 미세구조의 관찰로 원소첨가에 따른 샘플의 소결에너지 변화를 분석할 수 있었다. 제작된 시편의 정성분석 및 Chemical binding Energy를 측정하기 위해 X-ray Photo Spectroscopy (XPS)를 이용하였으며, 전기적인 특성 측정을위해 4-Point prove mesurement 방법을 사용하였다.

• Restorative Dentistry and Endodontics
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• v.19 no.1
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• pp.1-26
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• 1994

The purpose of this study was to investigate the dissolution components during corrosion of amalgams and to identify surface corrosion products in the modified Fusayama artificial saliva. Four type of amalgam alloys were used: low copper lathe cut amalgam alloy (Cavex 68), low copper spherical amalgam alloy (Caulk Spherical Alloy), high copper admixed amalgam alloy (Dispersalloy) and high copper single composition amalgam alloy (Tytin). Each amalgam alloy and Hg were triturated according to the manufacturer's direction by means of mechanical amalgamator (Capmaster, S.S.White), and then the triturated mass was inserted into the cylindrical metal mold which was 10mm in diameter and 2.0mm in height and condensed with compression of 150kg/$cm^2$ using oil pressor. The specimens were removed from the mold and stored at room temperature for 7 days and cleansed with distiled water for 30 minutes in an ultrasonic cleaner. The specimens were immersed in the modified Fusayama artificial saliva for the periods of 1 month, 3 months and 6 months. The amounts of Hg, Cu, Sn and Zn dissolved from each amalgam specimen immersed in the artificial saliva for the periods of 1 month, 3 months and 6 months were measured using Inductivity Coupled Plasma Atomic Emission Spectrometry (ICPQ-1000, Shimadzu, Japan) and amount of Ag dissolved from amalgam specimen was measured using Atomic Absorption Spectrophotometry (Atomic Absorption/Flame emission spectrophotometer M-670, Shimadzu, Japan). A surface corrosion products of specimens were analysed using Electron Spectroscopy Chemical Analyser (ESCA PHI-558, PERKIN ELMER, U.S.A.). The secondary image and back scattered image of corroded surface of specimens was observed under the SEM, and the corroded surface of specimens was analysed with the EDX. The following results were obtained. 1. The dissolution amount of Cu was the most in high copper admixed amalgam(Dispersalloy) and the least in high copper single composition amalgam(Tytin). 2. Sn and Zn were dissolved during all the experiment periods, and dissolution amounts were decreased as the time elapsed. 3. Initial surface corrosion products were ZnO and SnO. 4. Corrosion of ${\gamma}$ and ${\gamma}_2$ phase in low copper amalgams was observed and Ag-Cu eutectic alloy phase was corroded in low copper spherical amalgam(Caulk Sperical Alloy). 5. Corrosion of ${\gamma}$ and $\eta$' phase in high copper amalgams was observed and Ag-Cu eutectic alloy phase was corroded in high copper admixed amalgam(Dispersalloy). 6. Sn-Cl was produced in the subsurface of low copper amalgams and high copper admixed amalgam.

• Transactions on Electrical and Electronic Materials
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• v.18 no.1
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• pp.55-57
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• 2017

Amorphous oxide thin film transistors (TFTs) were fabricated with 0.5 wt% silicon doped zinc tin oxide (a-0.5SZTO) thin film deposited by radio frequency (RF) magnetron sputtering. In order to investigate the effect of annealing treatment on the electrical properties of TFTs, a-0.5SZTO thin films were annealed at three different temperatures ($300^{\circ}C$, $500^{\circ}C$, and $700^{\circ}C$ for 2 hours in a air atmosphere. The structural and electrical properties of a-0.5SZTO TFTs were measured using X-ray diffraction and a semiconductor analyzer. As annealing temperature increased from $300^{\circ}C$ to $500^{\circ}C$, no peak was observed. This provided crystalline properties indicating that the amorphous phase was observed up to $500^{\circ}C$. The electrical properties of a-0.5SZTO TFTs, such as the field effect mobility (${\mu}_{FE}$) of $24.31cm^2/Vs$, on current ($I_{ON}$) of $2.38{\times}10^{-4}A$, and subthreshold swing (S.S) of 0.59 V/decade improved with the thermal annealing treatment. This improvement was mainly due to the increased carrier concentration and decreased structural defects by rearranged atoms. However, when a-0.5SZTO TFTs were annealed at $700^{\circ}C$, a crystalline peak was observed. As a result, electrical properties degraded. ${\mu}_{FE}$ was $0.06cm^2/Vs$, $I_{ON}$ was $5.27{\times}10^{-7}A$, and S.S was 2.09 V/decade. This degradation of electrical properties was mainly due to increased interfacial and bulk trap densities of forming grain boundaries caused by the annealing treatment.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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• pp.203-204
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• 2009

The Indium Zinc Tin Oxide (IZTO) thin films for flexible display electrode were deposited on poly carbonate (PC) and polyethersulfone(PES) and glass substrates at room temperature by facing targets sputtering (FTS). Two different kinds of targets were installed on FTS system. One is ITO ($In_2O_3$ 90 wt.%, $SnO_2$ 10 wt.%), the other is IZO ($In_2O_3$ 90 wt.%, ZnO 10 wt.%). As-deposited IZTO thin films were investigated by a UV/VIS spectrometer, an X-ray diffractometer (XRD), an atomic force microscope (AFM) and a Hall Effect measurement system. As a result, we could prepare the IZTO thin films with the resistivity of under $10^{-4}\;[{\Omega}{\cdot}cm]$ and IZTO thin films deposited on glass substrate showed an average transmittance over 80% in visible range (400~800 nm) in all IZTO thin films except in IZTO thin film deposited at $O_2$ gas flow rate of 0.1[sccm].

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.402.2-402.2
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• 2016

In photoelectrochemical (PEC) water splitting, Cu2ZnSnS4 (CZTS) compound has attracted intense attention as a photocathode due to not only large optical absorption coefficient, but also earth-abundance of constituent elements and suitable band alignment. With rapid development of nanotechnology, one-dimensional nanostructures of CZTS have been investigated as a potential form to achieve high efficiency because the nanostructures are expected to be capable of capturing more light and enhancing charge separation and transport. Here, we report a well-controlled fabrication route for vertically-aligned CZTS nanorod arrays on anodic aluminium oxide (AAO) template via simple sol-gel process followed by deposition of ZnS or CdS buffer layers on the CZTS nanorod to enhance charge separation. The structure, morphology, composition, optical absorption, and PEC properties of the resulting CZTS nanorod samples were characterized using X-ray diffraction, Raman spectroscopy, transmission electron microscopy, energy dispersive X-ray spectrometry, scanning electron microscopy, and UV-vis spectroscopy.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2010.06a
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• pp.208-208
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• 2010

Indium zinc tin oxide (IZTO) thin films were studied as a possible alternative to indium tin oxide (ITO) films for providing low-cost transparent conducting oxide (TCO) for thin film photovoltaic devices. IZTO films were deposited onto glass substrates at room temperature. A dc/rf magnetron co-sputtering system equipped with a ceramic target of the same composition was used to deposit TCO films. Earlier studies showed that the resistivity value of $In_{0.6}Zn_{0.2}Sn_{0.2}O_{1.5}$ (IZTO20) films could be lowered to approximately $6{\times}10^{-4}ohm{\cdot}cm$ without sacrificing optical transparency and still maintaining amorphous structure through the optimization of process variables. The growth rate was kept at about 8 nm/min while the oxygen-to-argon pressure ratio varied from 0% to 7.5%. As-deposited films were always amorphous and showed strong oxygen pressure dependence of electrical resistivity and electron concentration values. Influence of forming gas anneal (FGA) at medium temperatures was also studied and proven effective in improving electrical properties. In this study, the chemical composition of the targets and the films varied around the $In_{0.6}Zn_{0.2}Sn_{0.2}O_{1.5}$ (IZTO20). It was the main objective of this paper to investigate how off-stoichiometry affected TCO characteristics including electrical resistivity and optical transmission. In addition to the composition effect, we have also studied how film properties changed with processing variables. IZTO thin films have shown their potential as a possible alternative to ITO thin films, in such way that they could be adopted in some applications where currently ITO and IZO thin films are being used. Our experimental results are compared to those obtained for commercial ITO thin films from solar cell application view point.

• Journal of Sensor Science and Technology
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• v.27 no.4
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• pp.221-226
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• 2018

Misfueling accidents significantly damage the engines of both gasoline and diesel vehicles, and should be avoided by rapid and accurate fuel discrimination. Gasoline fuel contains bioethanol. Thus, the detection of ethanol vapor produced by gasoline can be used to distinguish between gasoline and diesel. In the present study, Pt-doped $SnO_2$ hollow nanospheres, Mg-doped $In_2O_3$ hollow microspheres, and Pt-doped ZnO nanostructures have been used as gas sensors to discriminate between gasoline and diesel fuels. All three sensors are able to detect and discriminate between gases evaporating from gasoline and diesel. Among the sensors, the Mg-doped $In_2O_3$ hollow microspheres show a significant gas response (resistance ratio = 4.97) quickly (~3 s) after exposure to gasoline-evaporated gas at $225^{\circ}C$, but did not show any substantial response to diesel-evaporated gas. This demonstrates that gasoline and diesel fuels can be discriminated using small and cost-effective oxide semiconductor gas sensors.