• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.27 no.2
• /
• pp.121-125
• /
• 2014

In this research, nanocomposite layers consisting of poly (3,4,-ethylene dioxythiophene):polystyrene sulfonic acid (PEDOT:PSS) and CuO nanoparticles were investigated as hole transport layers in organic solar cells based on poly (3-hexylthiophene) (P3HT) as the electron donor and (6.6) phenyl-C61-butyric acid methyl ester (PCBM) as the electron acceptor. The addition of CuO nanoparticles to PEDOT:PSS layer improved the solar cell performance with 0.5% CuO nanoparticle concentration. At optimized concentration, CuO mixed PEDOT:PSS films had good electrical ($4.131{\Omega}{\cdot}cm$) and optical (transmittance > 90%) properties for using hole transporting layer. We investigated that improved solar cell performance with CuO nanoparticles mixed PEDOT:PSS films.

• Progress in Superconductivity and Cryogenics
• /
• v.5 no.3
• /
• pp.11-14
• /
• 2003

The detailed conditions of dc-sputtering for depositions of yttria-stabilized ZrO$_2$ (YSZ) films were investigated, while the films were grown on the CeO$_2$ template layers on biaxially textured Ni-tapes. The window of oxygen pressures for proper growth of YSZ films, which was dependent on sputtering powers, was determined by sufficient oxidations of the YSZ films and the de-oxidation of the target surface, which was required for rapid sputtering. The window turned out to be fairly wide under certain values of argon pressure. When the sputtering power was raised, the deposition rate increased without narrowing the window. The fabricated YSZ films showed good texture qualities and surface morphologies.

• Journal of Pharmaceutical Investigation
• /
• v.37 no.1
• /
• pp.7-13
• /
• 2007

To produce stable polymer coating layer using the interaction between metal stent and polymer layer, Ahx-HSAB was synthesized by coupling 6-aminoheanoic acid (Ahx) with N-Hydroxy succinimidyl 4-azidobenzonate (HSAB) containing photo reactive group. Then, Ahx-HSAB was applied to self·assembled monolayer (SAM) on $TiO_2$-coated surface, since one end of Ahx-HSAB was carboxyl acid which was known to be able to interact with $TiO_2$ surface. That SAM layer was incubated in 1% polycaprolacton (PCL) solution and photoreacted by ultraviolet light (254 nm) to produce the chemical bond between SAM and polymer layer, followed by PCL polymer coating ({\sim}5\;{\mu}m$) by the method of spray coating. The surface change was investigated by measuring of contact angle of the surface. The contact angle values of stainless steel (SS) surface, $TiO_2$-coated surface, SAM layer by Ahx-HSAB, photoreacted surface with PCL and PCL layer by spray coating were 70.48${\pm}$1.89, 38.57${\pm}$3.31, 60.14${\pm}$2.21, 54.91${\pm}$2.70 and 56.47${\pm}$2.12, respectively. The stability of polymer layers was tested by incubation of PCL-coated plates in 0.1M PBS buffer (pH 7.4, 0.05%, Tween 80) with vigorous shaking (200 rpm). While the poiymer layer prepared by these processes showed the intact surface morphology over 3 days, the polymer layers prepared by spray coating of PCL onto SS plate (control 1) and $TiO_2$-coated SS plate (control 2) were Peeled off in 3 days. Thus, the polymer coating method using SAM and photoreaction seems to be a effective method to obtain the stable polymer layer onto SS surface.

• Journal of the Institute of Electronics Engineers of Korea SD
• /
• v.37 no.6
• /
• pp.64-71
• /
• 2000

An optical switch composed of identical, equally-spaced $Ti:LiNbO_3$ three-waveguides was designed and fabricated. Patterned Ti was diffused into z-cut $LiNbO_3$ substrates. $SiO_2$ buffer layer was evaporated to reduce the propagation loss of TM mode, and Al electrodes of CPW structure were built on the layer for switching of the guided beam. The optical switching phenomenon was confirmed when a beam of ${\lambda}=1.3{\mu}m$ was launched into the center waveguide and an electric field was applied to detune the three waveguides symmetrically.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2001.07a
• /
• pp.45-49
• /
• 2001

We have investigated physical and electrical properties of the Hf $O_2$/HfS $i_{x}$/ $O_{y}$ thin film for alternative gate dielectrics in the metal-oxide-semiconductor device. The oxidation of Hf deposited directly on the Si substrate results in the H $f_{x}$/ $O_{y}$ interfacial layer and the high-k Hf $O_2$film simultaneously. Interestingly, the post-oxidation N2 annealing of the H102/H1Si70y thin films reduces(increases) the thickness of an amorphous HfS $i_{x}$/ $O_{y}$ layer(Hf $O_2$ layer). This phenomenon causes the increase of the effective dielectric constant, while maintaining the excellent interfacial properties. The hysteresis window in C-V curves and the midgap interface state density( $D_{itm}$) of Hf $O_2$/HfS $i_{x}$/ $O_{y}$ thin films less than 10 mV and ~3$\times$10$^{11}$ c $m^{-2}$ -eV without post-metallization annealing, respectively. The leakage current was also low (1$\times$10-s A/c $m^2$ at $V_{g}$ = +2 V). It is believed that these excellent results were obtained due to existence of the amorphous HfS $i_{x}$/ $O_{y}$ buffer layer. We also investigated the charge trapping characteristics using Fowler-Nordheim electron injection: We found that the degradation of Hf $O_2$/HfS $i_{x}$/ $O_{y}$ gate oxides is more severe when electrons were injected from the gate electrode.e electrode.e.e electrode.e.

• Proceedings of the Materials Research Society of Korea Conference
• /
• 1998.08a
• /
• pp.133.4-133
• /
• 1998

• Proceedings of the Korean Ceranic Society Conference
• /
• 2003.10a
• /
• pp.173.1-173
• /
• 2003

• Journal of the Korean institute of surface engineering
• /
• v.47 no.6
• /
• pp.341-346
• /
• 2014

Ga-doped ZnO (GZO) single layer and $SiO_2/GZO$ bi-layered films were deposited on Polycarbonate(PC) substrate by radio frequency magnetron sputtering. Influence of the structural, electrical, and optical properties of the films was considered. We have considered the influence of electron irradiation energy of 450 and 900 eV on the stuctural, electrical and optical properties of $SiO_2/GZO$ thin films. The optical transmittance in a visible wave length region increased with the electron irradiation energy. The electrical resistivity of the films were dependent on the electron's irradiation energy. The $SiO_2/GZO$ films irradiated at 900 eV were showen the lowest resistivity of $7.8{\times}10^{-3}{\Omega}cm$. The film which was irradiated by electron at 900 eV shows 84.3% optical transmittance and also shows lower than contact angle of $58^{\circ}$ in this study.

• Corrosion Science and Technology
• /
• v.2 no.4
• /
• pp.171-177
• /
• 2003

The electronic properties of the passive film formed on Fe-20Cr ferritic stainless steel in pH 8.5 buffer solution containing 0.05 M EDTA (ethylene diammine tetraacetic acid) were examined by the photocurrent measurements and Mott-Schottky analysis for the film. XPS depth profile for the film demonstrated that Cr content in the outermost layer of the passive film was higher in the solution with EDTA than that in the solution without EDTA, due to selective dissolution of Fe by EDTA. In the solution with EDTA, the passive film showed characteristics of an amorphous or highly disordered n-type semiconductor. The band gap energies of the passive film are estimated to be ~ 3.0 eV, irrespective of film formation potential from 0 to 700 $mV_SCE$ and of presence of EDTA. However, the donor density of the passive film formed in the solution with EDTA is much higher than that formed in the solution without EDTA, due to an increase in oxygen vacancy resulted from the dissolution of Fe-oxide in the outermost layer of the passive film. These results support the proposed model that the passive film formed on Fe-20Cr in pH 8.5 buffer solution mainly consists of Cr-substituted $\gamma$-$Fe_2O_3$.

• Proceedings of the Materials Research Society of Korea Conference
• /
• 2003.03a
• /
• pp.211-211
• /
• 2003

PbTiO$_3$ 씨앗층을 이용하여 완화형 강유전체 Pb(Mg$_{1}$3/Ta$_{2}$3/)O$_3$ (PMT) 박막의 페로브스카이트 상안정화와 열처리 조건에 따른 미세구조변화, 이에 따른 전기적 특성 변화에 관하여 조사하였다. PbTiO$_3$ 박막을 스핀코팅법으로 3000 rpm에서 20초간(111) 방향으로 배향된 Pt / Ti / SiO$_2$/ Si 기판에 증착하여 안정화된 페로브스카이트 박막을 얻었다. 이렇게 제조된 PbTiO$_3$를 Buffer 층으로 사용하고 그 위에 Pb(Mg$_{1}$3/Ta$_{2}$3/)O$_3$를 박막을 Spin coating방법으로 증착한 후, 급속열처리 방법(RTA)으로 550- $650^{\circ}C$ 사이에서 열처리하였다. 제조된 박막의 열처리 온도에 따른 미세구조 변화와 결정성을 XRD, SEM, TEM으로 분석하였고 박막의 저온 강유전 특성을 RT66A를 이용하여 평가하였다. Pb(Mg$_{1}$3/Ta$_{2}$3/)O$_3$ 박막의 경우 씨앗층이 없는 경우에는 pyrochlore상이 주상이었지만 씨앗층을 사용한 경우 페로브스카이트 상이 주상임을 확인하였고 열처리 온도가 증가할수록 페로브스카이트상의 상대적 양이 증가함을 확인하였다. 미세구조와 상의 변화에 따른 전기적 특성 변화에 관하여 자세하게 논의할 것이다.