• 한국신재생에너지학회:학술대회논문집
• /
• 2010.06a
• /
• pp.85.1-85.1
• /
• 2010

$Cu(In,Ga)Se_2$ (CIGS) thin film solar cell is currently 19.5% higher efficiency and developing a large area technology. The structure of CIGS solar cell that make five unit layers as back contact, light absorption, buffer, front transparent conducting electrode and antireflection to make them sequentially forming. Materials and various compositions of thin film unit which also manufacture a variety method used by the physical and chemical method for CIGS solar cell. The construction and performance test of evaporator for CIGS thin film solar cell has been done. The vapor pressures were changed by using vapor flux meter. The vapor pressure were copper (Cu) $2.1{\times}10^{-7}{\sim}3.0{\times}10^{-7}$ Torr, indium (In) $8.0{\times}10^{-7}{\sim}9.0{\times}10^{-7}$ Torr, gallium (Ga) $1.4{\times}10^{-7}{\sim}2.8{\times}10^{-7}$ Torr, and selenium (Se) $2.1{\times}10^{-6}{\sim}3.2{\times}10^{-6}$ Torr, respectively. The characteristics of the CIGS thin film was investigated by using X-ray diffraction (XRD), scanning electron microscopy/energy dispersive spectroscopy (SEM/EDS) and photoluminescence (PL) spectroscopy using a He-Ne laser. In PL spectrum, temperature dependencies of PL spectra were measured at 1137 nm wavelength.

• Current Applied Physics
• /
• v.18 no.12
• /
• pp.1571-1576
• /
• 2018

Recent study shows that the main reason for limiting CZTS device performance lies in the low open circuit voltage, and crucial factor that could affect the $V_{oc}$ is secondary phases like ZnS existing in absorber layer and its interfaces. In this work, the $Cu_2ZnSnS_4$ thin film solar cells were prepared by sputtering CuSn and CuZn alloy targets. Through tuning the Zn/Sn ratios of the CZTS thin films, the crystal structure, morphology, chemical composition and phase purity of CZTS thin films were characterized by X-Ray Diffraction (XRD), scanning electron microscopy (SEM) equipped with an energy dispersive spectrometer (EDS) and Raman spectroscopy. The statistics data show that the CZTS solar cell with a ratio of Zn/Sn = 1.2 have the best power convention efficiency of 5.07%. After HCl etching process, the CZTS thin film solar cell with the highest efficiency 5.41% was obtained, which demonstrated that CZTS film solar cells with high efficiency could be developed by sputtering CuSn and CuZn alloy targets.

• Journal of the Korean institute of surface engineering
• /
• v.48 no.2
• /
• pp.38-42
• /
• 2015

Atomic layer deposition (ALD) is essential for the fabrication of nanoscale electronic devices because it has excellent conformality, atomic scale thickness control, and large area uniformity. Metal thin films are one of the important material components for electronic devices as a conductor. As the size of electronic devices shrinks, the thickness of metal thin films is decreased down to few nanometers, and the metal films become non-continuous due to inherent island growth of metal below a critical thickness. So, fabrication of continuous metal thin films by ALD is fundamentally and practically important. Since ALD films are grown through self-saturated reactions between precursors on surface, initial growth characteristics significantly depend on the surface properties and the selection of precursors. In this work, we investigated ALD Pt on $TiO_2$ substrate by using trimethyl-methyl-cyclopentadienyl-Platinum ($MeCpPtMe_3$) precursor and $O_3$ reactant. By using $O_3$ instead of $O_2$, initial nucleation rate of ALD Pt was increased on $TiO_2$ surface, resulting in formation of continuous thin Pt films. Morphologies of ALD Pt on $TiO_2$ were characterized by using Scanning Electron Microscope (SEM) and Energy-Dispersive X-ray Spectroscopy (EDS). Crystallinity of ALD Pt on $TiO_2$ correlated with its growth characteristics was analyzed by X-Ray Diffraction (XRD).

• Proceedings of the Korean Vacuum Society Conference
• /
• 2012.08a
• /
• pp.278-279
• /
• 2012

최근 들어 세계적인 고유가 행진과 화석연료 고갈에 대응하기 위하여 대체 에너지원 발굴에 대한 필요성이 높아지고 있다. 그 중 CIGS 박막 태양전지는 미래 신재생 에너지 자원의 가장 유망한 후보군 중 하나이다. 기존의 Si 기반의 태양전지의 경우 시간경과에 따른 효율 저하, 높은 재료비, 복잡한 공정으로 인하여 대량생산이 힘든 단점을 가지고 있다. 반면 박막 태양전지의 경우 생산 원가를 낮출 수 있는 태양전지 제조기술로서는 2세대 태양전지로 불리우며, 에너지 변환 효율과 생산 원가에서 우월성을 가진다. 그리고 이러한 CIGS 박막 태양전지를 단일 CIGS 타겟을 이용하여 스퍼터링 공정으로 제작하면 기존에 사용되었던 동시 증발법에 비해서 간단하고 대면적 코팅 및 대량 생산이 가능하다. 본 연구에서 사용된 기판으로는 $25{\times}25mm$ 크기의 Soda Lime Glass (SLG) 위에 DC 마그네트론 스퍼터링 공정으로 Mo가 $1{\mu}m$ 증착된 시편을 이용하여, 2 inch 단일 CIGS 타겟 (MATERION, CIGS Target 25-17.5-7.5-50 at%)을 기판 가열하여 증착하였다. RF 파워는 80 W, 기판 온도는 RT, 100, 200, 300, $400^{\circ}C$로 가열 후 증착하였고, CIGS 박막의 두께는 약 $1{\mu}m$로 일정하게 하였다. CIGS/Mo 박막의 파워별 미세구조 분석을 위해 X-ray Diffraction (XRD, BRUKER GADDS)로 측정하였으며, 박막의 결정립 크기를 확인하기 위해 Field Emission Scanning Electron Microscopy (FE-SEM, HITACHI)을 사용하여 측정하였다. 조건별 박막의 조성 분석 및 표면조도는 Energy Dispersive X-ray Spectroscopy (EDS, HORIBA 7395-H)와 Atomic Force Microscopy (AFM)을 이용하여 각각 평가하였다. 마지막으로 광학적 특성을 평가하고 박막의 밴드갭 에너지를 계산하기 위해서 190 nm에서 1,100 nm의 영역 대에서 자외선 광학 측정기(UV-Vis, HP-8453, AGLIENT)로 투과도를 측정하여 밴드갭 에너지를 계산하였다. 증착된 CIGS 박막은 기판 온도가 증가함에 따라 결정립 크기가 커지는 경향을 보였다. 이는 기판 상에 도달한 스퍼터 원자의 확산 에너지 증가로 인한 것으로 생각되어진다. 또한, 기판온도에 따른 결정립 성장 변화는 4성분계의 박막의 조성 및 핵생성 밀도와 관련되어 설명되어질 것이다.

• Journal of Soil and Groundwater Environment
• /
• v.25 no.1
• /
• pp.95-105
• /
• 2020

In this study, iron nanoparticles impregnated hydrochar (FeNPs@HC) was synthesized using lignocellulosic waste and simple one-pot synthetic method. During hydrothermal carbonization (HTC) process, the mixture of lignocellulosic waste and ferric nitrate (0.1~0.5 M) as a precursor of iron nanoparticles was added and heated to 220℃ for 3 h in a teflon sealed autoclave, followed by calcination at 600℃ in N₂ atmosphere for 1 h. For the characterization of the as-prepared materials, X-ray diffraction (XRD), cation exchange capacity (CEC), fourier transform infrared spectrometer (FT-IR), Brunauer-Emmett-Teller (BET), transmission electron microscope (TEM), Energy Dispersive X-ray Spectroscopy (EDS) were used. The change of Fe(III) concentration in the feedstock influenced characteristics of produced FeNPs@HC and removal efficiency towards As(V) and Pb(II). According to the Langmuir isotherm test, maximum As(V) and Pb(II) adsorption capacity of Fe_0.25NPs@HC were found to be 11.81 and 116.28 mg/g respectively. The results of this study suggest that FeNPs@HC can be potentially used as an adsorbent or soil amendment for remediation of groundwater or soil contaminated with arsenic and cation heavy metals.

• Journal of Electrochemical Science and Technology
• /
• v.9 no.3
• /
• pp.202-211
• /
• 2018

In this work, Fe-Pd alloy films have been electrodeposited on different substrates using an electrolyte containing $[Pd(NH_3)_4]^{2+}$ (0.02 M) and $[Fe-Citrate]^{2+}$ (0.2 M). The influences of substrate and overpotential on chemical composition, nucleation and growth kinetics as well as the electrodeposited films morphology have been investigated using energy dispersive X-ray spectroscopy (EDS), current-time transients, scanning electron microscopy (SEM), atomic force microscopy (AFM) and X-ray diffraction (XRD) patterns. In all substrates - brass, copper and sputtered fluorine doped tin oxide on glass (FTO/glass) - Fe content of the electrodeposited alloys increases by increasing the overpotential. Also the cathodic current efficiency is low due to high rate of $H_2$ co-reduction. Regarding the chronoamperometry current-time transients, it has been demonstrated that the nucleation mechanism is instantaneous with a typical three dimensional (3D) diffusion-controlled growth in the case of brass and copper substrates; while for FTO, the growth mode changes to 3D progressive. At a constant overpotential, the calculated number of active nucleation sites for metallic substrates is much higher than that of FTO/glass; however by increasing the overpotential, the number of active nucleation sites increases. The SEM micrographs as well as the XRD patterns reveal the formation of Fe-Pd alloy thin films with nanostructure arrangement and ultra-fine grains.

• Proceedings of the Korean Institute of Surface Engineering Conference
• /
• 2017.05a
• /
• pp.154-154
• /
• 2017

Ti-6Al-4V alloys are widely used as metal-lic biomaterials in dentistry and orthopedics due to its excellent biocompatibility and me-chanical properties. However, because of low biological activity, it is difficult to form bone growth directly on the surface of titanium implants. For this reason, surface treatment of plasma electrolytic oxidation(PEO) was used for dental implants. To enhance bioac-tivity on the surface, strontium(Sr) and sili-con(Si) ions can be added to PEO treated sur-face in the electrolyte containing these ions. The presence of Sr in the coating enhances osteoblast activity and differentiation, where-as it inhibits osteoclast production and prolif-eration. And Si has been found to be essen-tial for normal bone, cartilage growth, and development. In this study, electrochemical characteristics of Ca, P, Sr, and Si ions from PEO-treated Ti-6Al-4V alloy surface was re-searched using various experimental instruments. DC power is used and Ti-6Al-4V al-loy was subjected to a voltage of 280 V for 3 minutes in the electrolyte containing 5, 10, 20M% Sr ion and 5M% Si ion. The morphol-ogies of PEO-treated Ti-6Al-4V alloy by electrochemical anodization were examined by field-emission scanning electron micro-scopes (FE-SEM), energy dispersive x-ray spectroscopy (EDS), x-ray diffraction (XRD) and corrosion analysis using AC impedance and potentiodynamic polarization test in 0.9% NaCl solution at similar body tempera-ture using a potentiostat with a scan rate of 1.67mV/s and potential range from -1500mV to + 2000mV.

• Journal of Powder Materials
• /
• v.20 no.6
• /
• pp.432-438
• /
• 2013

In this study, analysis on the oxidation behavior was conducted by a series of high-temperature oxidation tests at both $800^{\circ}C$, $900^{\circ}C$ and 1000 in the air with sintered STS 316L. The weight gain of each oxidized specimen was measured, the oxidized surface morphologies and composition of oxidation layer were analyzed with Scanning Electron Microscope-Energy Dispersive x-ray Spectroscopy (SEM-EDS), finally, the phase change and composition of the oxidized specimen were shown by X-Ray Diffraction (XRD). As a result, the weight gain increased sharply at $1000^{\circ}C$ when oxidation test was conducted for 210 hours. Also, a plentiful of pores were observed in the surface oxidation layers at $900^{\circ}C$ for 210 hours. In addition, the following conclusions on oxidation behavior of sintered STS 316L can be obtained: $Cr_2O_3$ can be formed on pores by influxing oxygen through open-pores, $(Fe_{0.6}Cr_{0.4})_2O_3$ can be generated on the inner oxidation layer, and $Fe_2O_3$ was on the outer oxidation layer. Also, $NiFe_2O_4$ could be precipitated if the oxidation time was kept longer.

• Korean Journal of Materials Research
• /
• v.24 no.1
• /
• pp.48-52
• /
• 2014

The Mg-enriched magnesium aluminum silicate (MAS) glass is known for its higher mechanical strength and chemical resistance. Among such glasses, cordierite ($Mg_2Al_4Si_5O_{18}$) is well known to have a low thermal expansion and low melting point. Polycrystalline engineering ceramics such as alumina can be strengthened by a surface modification with low thermal expansion materials. The present study involves the synthesis of cordierite by a sol-gel process and investigates the effect of glass penetration on the surface of alumina. The cordierite powders were prepared from $Al(OC_3H_7)_3$, $Mg(OC_2H_5)_2$ and tetraethyl orthosilicate by hydrolysis and condensation reaction. The cordierite powders were characterized by X-ray diffraction (XRD, Rigaku), scanning electron microscope (SEM, JEOL: JSM-5610), energy dispersive spectroscopy (EDS, JEOL: JSM-5610), and universal testing machine (UTM, INSTRON). The X-ray diffraction patterns showed that the synthesized particles were ${\mu}$-cordierite calcined at $1100^{\circ}C$ for 1 h. The shape of synthesized cordierite was changed from ${\mu}$-cordierite to ${\alpha}$-cordierite with increasing calcination temperature. Synthesized cordierite was used for surface modification of alumina. Cordierite powders penetrated deeply into the alumina sample along grain boundaries with increasing temperature. The results of surface modification tests showed that the strength of the prepared alumina sample increased after surface modification. The strength of a surface modified with synthesized cordierite increased the most, to about 134.6MPa.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.34 no.4
• /
• pp.256-261
• /
• 2021

Indium-doped Mg_0.05Zn_0.95O thin films were deposited on glass substrates by a sol-gel method. Three types of indium precursors such as indium chloride, indium acetate, and indium nitrate were used as doping sources. Physical properties of fabricated thin films were analyzed through XRD (x-ray diffraction), UV-vis spectrophotometer, Hall effect measurement, and EDS (energy dispersive x-ray spectroscopy). All In-doped thin films grown in this study exhibited a preferred orientation of (002) with over 80% transmittance. The results showed that the Mg_0.05Zn_0.95O thin film from indium chloride as the indium precursor has higher crystallinity and transmittance with lower resistivity when compared with those from other indium precursors.