• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.05c
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• pp.197-200
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• 2001

반응성 스퍼터링법으로 TaN film을 증착한 후 열처리온도에 따라 TaN 박막의 $R_s$(sheet resistance) 특성을 평가하고 미세구조 변화에 따른 전기적 특성 변화를 고찰하였다. TaN 박막을 열처리한 결과 $400^{\circ}C$에서 $600^{\circ}C$까지는 (110)의 회절피크만 보이다가 $700^{\circ}C$ 에서는 (200)의 회절 피크가 나타났고 특히 as-deposition 상태와 $300^{\circ}C$ 열처리시에는 Ta와 TaN 상이 혼재한 상태로 나타났으며 전기저항 변화는 as-deposition 상태가 $140{\Omega}/{\square}$로 가장 높았으며 열처리 온도가 증가함에 따라 저항은 점차적으로 감소하다가 $600^{\circ}C$와 $700^{\circ}C$에서는 전기저항이 다시 증가하였다. $500^{\circ}C$까지는 표면 형상이나 표면조도보다는 열처리 온도의 증가에 따른 TaN 박막의 결정구조 변화가 전기저항에 영향을 주는 주 요인으로 작용하고, $600^{\circ}C$와 $700^{\circ}C$ 열처리시에 결정립의 증가에도 불구하고 전기저항이 증가하는 것은 고온 열처리에 의한 표면조도가 증가하였기 때문이라고 생각된다.

• Proceedings of the Optical Society of Korea Conference
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• 2001.02a
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• pp.6-11
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• 2001

More than ten kinds of oxide thin films and their heterostructure have been successfully fabricated on SrTiO$_3$(001) substrates by laser molecular beam epitaxy (laser MBE). Measurements of atomic force microscopy (AFM), high-resolution transmission electron microscopy (HRTEM) and X-ray small-angle reflectivity reveal that the surfaces and interfaces are atom-level-smooth. The unit cell layers and the lattice structure are perfect. The electrical and optical properties of BaTiO$_3$-x thin films and BaTiO$_3$/SrTiO$_3$ (BTO/STO) superlattices were examined. The all-perovskite oxide P-N junctions have been successfully fabricated and the better I-V curves were observed.

• Environmental Engineering Research
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• v.24 no.4
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• pp.646-653
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• 2019

Recovery of valuable metals in the industrial wastewater and sludge has attracted an attention owing to limited metallic resources in the earth. In this study, we firstly fabricated Ti/Ir-Ru electrodes by spin coating technique for effective recovery of Cu in electrowinning process. Two different Ti/Ir-Ru electrodes were fabricated using 100 and 500 mM of precursors (i.e., Ir-Ru). SEM-EDX and AFM revealed that Ir and Ru were homogenously distributed on the surface of Ti plate by the spin coating, in particular the electrode prepared by 500 mM showed distinct boundary line between Ir-Ru layer and Ti substrate. XRD, XPS, and cyclic voltammetry also revealed that characteristics of IrO₂, RuO₂, and TiO₂ and its electrocatalytic property increased as the concentration of coating precursor increased. Finally, we carried out Cu recovery experiments using two Ti/Ir-Ru as anodes in electrowinning process, showing that both anodes showed a complete removal of Cu (1 and 10 g/L) within 6 h reaction, but much higher kinetic rate constant was obtained by the anode prepared by 500 mM. The findings in this study can provide a fundamental knowledge for surface characteristics of Ti/Ir-Ru electrode prepared by spin coating method and its potential feasibility for effective electrowinning process.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.15 no.9
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• pp.764-769
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• 2002

The effect of excess Bi contents on the ferroelectric properties of B $i_{3.25}$ L $a_{0.75}$ $Ti_3$ $O_{12}$ (BLT) thin films has been investigated. Bismuth lanthanum titanate thin films with excess Bi contents were prepared onto Pt/Ti/ $SiO_2$/Si substrate by metalorganic decomposition (MOD) technique. The structure and morphology of the films were analyzed using X-ray diffraction (XRD) and atomic force microscopy (AFM), respectively. From the XRD analysis, BLT thin films show polycrystalline structure and the layered-perovskite phase was obtained over 10% excess of Bi contents. As a result of ferroelectric characteristics related to the Bi content of the BLT thin film, the remanent polarization and dielectric constant decreased with increasing over Bi content of 10% excess. The BLT film with Bi content of 10% excess was measured to have a dielectric constant of 326 and dielectric loss of 0.024. The BLT thin films showed little polarization fatigue test up to 3.5$\times$10$^{9}$ bipolar switching cycling.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.22 no.5
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• pp.419-424
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• 2009

ZnO films doped with different contents of indium ($0.1{\sim}10$ at.%) were deposited on Si (111) substrate by Pulsed Laser Deposition (PLD). The structural, electrical and optical properties of the films were investigated using XRD, AFM, Hall and PL measurement. Results showed that un-doped ZnO film had (002) plane as the c-axis orientated growth, whereas indium doped ZnO films exhibited the peak of (002) and the weak (101) plane. In addition, in the indium doped ZnO films, the electron concentration is ten times higher than that of un-doped ZnO film, while the resistivity is ten times lower than that of un-doped ZnO film. The indium doped ZnO films have UV emission about 380 nm and show a red shift with increasing contents of indium. The I-V curve of the fabricated diode show the typical diode characteristics and have the turn on voltage of about 2 V.

• Proceedings of the Membrane Society of Korea Conference
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• 2004.05a
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• pp.207-210
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• 2004

The pore-filled anion-exchange membranes were prepared in this study with an asymmetric poly(vinylidene fluoride)(PVDF) membrane as a nascent membrane and poly(vinylbenzyl chloride)(PVBCl) as a polyelectrolyte. The solution of PVBCI having the chloromethylate aryl ring of 80 percents and 1,4-diaminobicyclo [2,2,2]octane(DABCO) was made with the solvent of tetrahydrofuran(THF) and N,N-Dimethylformamide(DMF), which is in the rotio of 8:2. A new preparation method in this study, i.e. in-situ crosslinking, enabled us to produce the pore-filled membranes without change of size, and to control the properties of final membrane with various degree of cross-linking. From the result of surface morphologies of SEM and AFM the polyelectrolyte exists in the pores of nascent membrane as a certain configuration. From the investigation of the solvent affecting much to the permeability and rejection, it was found. that the membranes using DMF and THF showed better performances than the membranes produced by THF only. The water permeability of the final membrane at low pressure(100㎪) showed a typical ultrafiltation membrane's permeability (8-10kg/㎡hr) and good values of rejection(55∼60 percent).

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.52 no.5
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• pp.213-213
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• 2003

We investigated the monolayer behavior at the air-water interface with metal solution, the surface morphologies and the electrical properties such as conductivity, The calculated conductivity values of pure water subphase and its complexes with L $i^{+}$ ions are 5.6$\times$10$^{-l6}$ and 1.9$\times$10$^{-14}$ [S/cm], respectively. And the calculated barrier height D values of pure water subphase and its complexes with Li. ions are 0.70 and 0.66 [eV], respectively. We also attempted to fabricate a crown dendrimer Langmuir-Blodgett (LB) films containing functional end group that could form a complex structure with metal ions. Also, we investigated the surface activity of dendrimer films at air-water interface. In AFM images. the larger domains irregularly shaped structures on the top while the smaller ones were free from such defects. In conclusion, it is demonstrated that the metal ion around dendrimer and polymer included crown function group can contribute to make formation of network structure among crown function group and result in change of electrical properties.s.s.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.52 no.5
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• pp.213-218
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• 2003

We investigated the monolayer behavior at the air-water interface with metal solution, the surface morphologies and the electrical properties such as conductivity, The calculated conductivity values of pure water subphase and its complexes with L $i^{+}$ ions are 5.6$\times$10$^{-l6}$ and 1.9$\times$10$^{-14}$ [S/cm], respectively. And the calculated barrier height D values of pure water subphase and its complexes with Li. ions are 0.70 and 0.66 [eV], respectively. We also attempted to fabricate a crown dendrimer Langmuir-Blodgett (LB) films containing functional end group that could form a complex structure with metal ions. Also, we investigated the surface activity of dendrimer films at air-water interface. In AFM images. the larger domains irregularly shaped structures on the top while the smaller ones were free from such defects. In conclusion, it is demonstrated that the metal ion around dendrimer and polymer included crown function group can contribute to make formation of network structure among crown function group and result in change of electrical properties.s.s.

• Journal of the Korean institute of surface engineering
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• v.41 no.3
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• pp.102-108
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• 2008

In this paper, the LiF and polymer thin film as passivation layer have been evaporated on green OLED devices. HDPE, polyacenaphthylene, polytetrafluoroethylene, poly(2,6-dimethyl-1,4-pheneylene oxide), poly sulfone and poly(dimer-acid-co-alkyl poly-amine) have been used as polymer materials. The optical transmittance of evaporated polymer thin film was very good as an above 90% in visible range. The morphology of polymer thin film was measured by AFM. As a result of the measurement average roughness($R_a$) value of the polysulfone was very low as 2.2 nm. The green OLED devices with a structure of ITO/HIL/HTL/EML/Buffer/Al in series of various passivation films were fabricated and analyzed. It was observed that an OLED device with LiF as first passivation film has shown the good electrical and optical property, and all kind of polymer films did not influence on the I-V-L characteristics and the life time of OLED devices. Therefore, we found that polymer layer played a key role as a buffer layer between the inorganic passivation layers to relieve the stress of the inorganic layers.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.1347-1348
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• 2007

In this paper, ITO gate electrode surface was modified using $O_2$ plasma and organic gate insulating layers were deposited on the ITO surface using plasma polymerization technique. In order to investigate the influence of the plasma coupling method and plasma conditions on the plasma polymerized methyl methacrylate (ppMMA) thin film properties, inductively coupled (ICP) and capacitively coupled plasma (CCP) were used to generate the plasma and the plasma parameters were varied. The ppMMAs were investigated using atomic force microscopy (AFM) and a Fourier Transform Infrared (FT-IR) spectroscopy. Dielectric constants of the ppMMA thin films were investigated using a impedance analyzer (HP4192A, LF Impedance Analyzer). Current-Voltage (I-V) characteristics of the organic thin film transistors (OTFTs) were investigated using a source measurement unit (SMU: Keithley 2612). Proposed method can be applied to dry-process to fabricate OTFTs during overall fabricating steps.