• Journal of IKEEE
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• v.24 no.1
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• pp.59-66
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• 2020

In this study, the characteristics of ITO thin film was investigated to finding a low cost and highly transparent electrodes for display of mobile communication devices. The ITO film was deposited by DC magnetron sputter. The experimental conditions were changed as follows: 1. ambient pressure changed 1 to 3 mTorr with 1mTorr step, 2. bias electric voltage changed with 10V step. The chamber was pumped out by rotary pump until 10^-3Torr then the diffusion pump was used to lower the pressure of 10^-6Torr. The results shows us the film growth was obvious when the bias voltage was larger than 300V, but the overall thickness tendency was existed: the more voltage is the thicker thickness. At 330V bias voltage condition, the deposition rate was the largest and apparent grain was showed.

• Journal of the Korea Institute of Military Science and Technology
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• v.7 no.2 s.17
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• pp.81-87
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• 2004

Semiconductor thick film gas sensors based on tin oxide are fabricated and their gas response characteristics are examined for four simulant gases of chemical warfare agent (CWA)s. The sensing materials are prepared in three different sets. 1) The Pt or Pd $(1,\;2,\;3\;wt.\%)$ as catalyst is impregnated in the base material of $SnO_2$ by impregnation method.2) $Al_2O_3\;(0,\;4,\;12,\;20\;wt.\%),\;In_2O_3\;(1,\;2,\;3\;wt.\%),\;WO_3\;(1,\;2,\;3\;wt.\%),\;TiO_2\;(3,\;5,\;10\;wt.\%)$ or $SiO_2\;(3,\;5,\;10\;wt.\%)$ is added to $SnO_2$ by physical ball milling process. 3) ZnO $(1,\;2,\;3,\;4,\;5\;wt.\%)$ or $ZrO_2\;(1,\;3,\;5\;wt.\%)$ is added to $SnO_2$ by co-precipitation method. Surface morphology, particle size, and specific surface area of fabricated sensing films are performed by the SEM, XRD and BET respectively. Response characteristics are examined for simulant gases with temperature in the range 200 to $400^{\circ}C$, with different gas concentrations. These sensors have high sensitivities more than $50\%$ at 500ppb concentration for test gases and also have shown good repetition tests. Four sensing materials are selected with good sensitivity and stability and are fabricated as a sensor array A sensor array Identities among the four simulant gases through the principal component analysis (PCA). High sensitivity is acquired by using the semiconductor thick film gas sensors and four CWA gases are classified by using a sensor array through PCA.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.411-412
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• 2008

We have studied a property change of organic light-emitting diodes (OLED) due to an indium tin oxide (ITO) surface reformation. The characteristics of OLED were improved by oxygen plasma processing of an ITO in this work. ITO is widely used as a transparent electrode in light-emitting devices, and the OLED device performance is sensitive to the surface properties of the ITO. The OLED devices with the structure of ITO/TPD(50nm)/$Alq_3$(70nm)/LiF(0.5nm)/Al(100nm) were fabricated, and the surface properties of ITO were investigated by using various characterization techniques. The oxygen plasma process of an ITO was processed by using RF power of 125W and oxygen partial pressure of $2\times10^{-2}$ Torr. The oxygen plasma processing of an ITO processed for 0/1/2/3/4min. Current-voltage-luminance characteristics of the devices show that turn-on voltage is 4V for 2min device and the luminance reaches about 27,000cd/$m^2$ for 4min device. The current efficiency shows that 3min device becomes saturated to be about 8cd/ A. They show that emission was from the $Alq_3$ layer, because the peak wavelength is about 525nm. View angle-dependent emission spectra show that the emission intensity decreases as the angle increases.

• Transactions on Electrical and Electronic Materials
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• v.16 no.3
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• pp.124-129
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• 2015

Organic electronics are the domain in which the components and circuits are made of organic materials. This new electronics help to realize electronic and optoelectronic devices on flexible substrates. In recent years, organic materials have replaced conventional semiconductors in many electronic components such as, organic light-emitting diodes (OLEDs), organic field-effect transistors (OFETs) and organic photovoltaic (OPVs). It is well known that organic light emitting diodes (OLEDs) have many advantages in comparison with inorganic light-emitting diodes LEDs. These advantages include the low price of manufacturing, large area of electroluminescent display, uniform emission and lower the requirement for power. The aim of this paper is to model polymer LEDs and OLEDs made with small molecules for studying the electrical and optical characteristics. The purpose of this modeling process is, to obtain information about the running of OLEDs, as well as, the injection and charge transport mechanisms. The first simulation structure used in this paper is a mono layer device; typically consisting of the poly (2-methoxy-5(2'-ethyl) hexoxy-phenylenevinylene) (MEH-PPV) polymer sandwiched between an anode with a high work function, usually an indium tin oxide (ITO) substrate, and a cathode with a relatively low work function, such as Al. Electrons will then be injected from the cathode and recombine with electron holes injected from the anode, emitting light. In the second structure, we replaced MEH-PPV by tris (8-hydroxyquinolinato) aluminum (Alq₃). This simulation uses, the Poole-Frenkel -like mobility model and the Langevin bimolecular recombination model as the transport and recombination mechanism. These models are enabled in ATLAS- SILVACO. To optimize OLED performance, we propose to change some parameters in this device, such as doping concentration, thickness and electrode materials.

• Bulletin of the Korean Chemical Society
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• v.32 no.10
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• pp.3629-3633
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• 2011

The effect of a dense $TiO_2$ blocking layer prepared using the sol-gel method on the performance of dye-sensitized solar cells was studied. The blocking layer formed directly on the working electrode, separated it from the electrolyte, and prevented the back transfer of electrons from the electrode to the electrolyte. The dyesensitized solar cells were prepared with a working electrode of fluorine-doped tin oxide glass coated with a blocking layer of dense $TiO_2$, a dye-attached mesoporous $TiO_2$ film, and a nano-gel electrolyte, and a counter electrode of Pt-deposited FTO glass. The gel processing conditions and heat treatment temperature for blocking layer formation affected the morphology and performance of the cells, and their optimal values were determined. The introduction of the blocking layer increased the conversion efficiency of the cell by 7.37% for the cell without a blocking layer to 8.55% for the cell with a dense $TiO_2$ blocking layer, under standard illumination conditions. The short-circuit current density ($J_{sc}$) and open-circuit voltage ($V_{oc}$) also were increased by the addition of a dense $TiO_2$ blocking layer.

• Composites Research
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• v.23 no.6
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• pp.1-6
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• 2010

The electrical conductivity of carbon-fiber reinforced plastics (CFRP's) has been improved by indium-tin oxide (ITO) nano-particle coating on carbon fibers for the purpose of lightning strike protection of composite fuselage skins. ITO nano-particles were coated on the surface of carbon fibers by spraying the colloidal suspension with 10~40% ITO content. The electrical conductivity of the CFRP has been increased more than three times after ITO coating, comparable to or higher than that of B-787 composite fuselage skins with metal wire-meshes on the outer surface, without sacrificing the tensile property due to the existence of nano-particles at fiber-matrix interface. The damage area by the simulated lightning strike was also verified for different materials and conditions by using ultrasonic C-scan image. As the electrical conductivity of 40% nano-ITO coated sample surpass that of the B-787 sample, the damage area by lightning strike also appeared comparable to that of the materials currently employed for composite fuselage construction.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.40 no.1
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• pp.11-19
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• 2003

A micro sensor array with 4 discrete sensors integrated on a microhotplate was developed for identifying the kinds and quantities of explosive gases. The sensor array consisited of four tin oxide-based thin films with the high and broad sensitivity to the tested explosive gases and uniform thermal distribution on the plate. The microhotplate, using silicon substrate with N/O/N membrane, dangling in air by Al bonding wires, and controlling the thickness by chemical mechanical process (CMP), has been designed and fabricated. By employing the sensitivity signal of the sensor array at 40$0^{\circ}C$, we could reliably classily the kinds and quantities of the explosive gases like butan, propane, LPG, and carbon monoxide within the range of threshold limit values (TLVs), employing principal component analysis (PCA).

• Corrosion Science and Technology
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• v.11 no.2
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• pp.65-69
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• 2012

One dimensional(1D) $Na_2Ti_6O_{13}$ nanorods with 70 nm in diameter was synthesized by a molten salt method. Using the synthesized nanorods, about 750 nm thick $Na_2Ti_6O_{13}$ film was coated on Fluorine-doped tin oxide(FTO) glasss substrate by the Layer-by-layer self-assembly(LBL-SA) method in which a repetitive self-assembling of ions containing an opposite electric charge in an aqueous solution was utilized. Using the Kubelka-Munk function, the band gap energy of the 1D-$Na_2Ti_6O_{13}$ nanorods was nalyzed to be 3.5 eV. On the other hand, the band gap energy of the $Na_2Ti_6O_{13}$ film coated on FTO was found to be a reduced value of 2.9 eV, resulting from the nano-scale and high porosity of the film processed by LBL-SA method, which was favorable for the photo absorption capability. A significant improvement of photocurrent and onset voltage was observed with the $Na_2Ti_6O_{13}$ film incorporated into the conventional $Fe_2O_3$ photoelectrode: the photocurrent increased from 0.25 to 0.82 mA/$cm^2$, the onset voltage decreased from 0.95 to 0.78 V.

• Journal of the Semiconductor & Display Technology
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• v.7 no.2
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• pp.49-53
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• 2008

The yellow base polymer light emitting diodes(PLEDs) with double emission and hole blocking layers were prepared to improve the light efficiency. ITO(indium tin oxide) and PEDOT : PSS[poly(3,4-ethylenedioxythiophene) : poly(styrene sulfolnate)] were used as cathode and hole transport materials. The PFO[poly(9,9-dioctylfluorene)] and MEH-PPV[poly(2-methoxy-5(2-ethylhe xoxy)-1,4-phenylenevinyle)] were used as the light emitting host and guest materials, respectively. TPBI[Tpbi1,3,5-tris(N-phenylbenzimidazol-2-yl)benzene] was used as hole blocking layer. To investigate the optimization of device structure, we prepared four kinds of PLED devices with different structures such as single emission layer(PFO : MEH-PPV), two double emission layer(PFO/PFO : MEH-PPV, PFO : MEH-PPV/PFO) and double emission layer with hole blocking layer(PFO/PFO : MEH-PPV/TPBI). The electrical and optical properties of prepared devices were compared. The prepared PLED showed yellow emission color with CIE color coordinates of x = 0.48, y = 0.48 at the applied voltage of 14V. The maximum luminance and current density were found to be about 3920 cd/$m^2$ and 130 mA/$cm^2$ at 14V, respectively for the PLED device with the structure of ITO/PEDOT : PSS/PFO/PFO : MEH-PPV/TPBI/LiF/Al.

• Proceedings of the Korean Vacuum Society Conference
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• 1999.07a
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• pp.200-200
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• 1999

^g , pp V (Poly-para phenylene vinylene) 유도체와^g , pp P(Poly-para phennylene) 유도체에 Ar, H2, N2 및 O2 등의 이온을 조사하여 PL(Photoluminescence)의 변화를 실험하였다. 각각의 전도성 고분자는 ITO9indium tin oxide)가 증착되어 있는 유리기판위에 spin coating을 하였으며 이렇게 처리된 전도성 고분자의 표면에 이온을 조사하였다. 여기에서 조사된 이온의 가속 에너지는 300eV에서 700eV까지 변화시켰고 이온 조사량은 1$\times$1013ions/cm2에서 1$\times$1017ions/cm2까지 변화시켰다. 이때 이온빔의 전류밀도는 0.2$\mu\textrm{A}$/$\textrm{cm}^2$이하로 고정하였으며 chamber내의 진공도는 $1.5\times$10-4Torr를 유지하였다. 이온 빔처리후 불안정한 고분자의 표면이 대기와 반응하는 것을 어느정도 방지하기 위해 이온 빔으로 처리된 시료를 chamber의 내부에 일정시간동안 방치하였다. Ar, H등의 이온으로 처리된 MEH-PPV의 경우는 PL의 세기가 감소하였고 이온 조사량이 1016ions/cm2 보다 클 때 PL의 세기는 급속히 감소하였다.^g , pp V와^g , pp P 유도체의 경우는 특정 이온 조사량에서 PL의 증가현상을 보였는데^g , pp P 도체중에서 P3의 경우를 보면 이온 빔 에너지가 300eV이고 이온 전류 밀도가 0.05$\mu\textrm{A}$/$\textrm{cm}^2$인 N2이온을 조사하면 이온 조사량이 1$\times$1013ions/cm2가 될 때 PL의 세기가 39%까지 증가하였다. PL의 변화에 대한 비교를 위해 이온빔으로 처리된 시료와 처리되지 않은 시료의 UV흡수스펙트럼과 IR 흡수 스펙트럼을 분석하였다. 본 실험에 사용된 모든 시료의 PL 세기는 1016ons/cm2이상의 dose에서 급격한 감소 현상을 나타내었고 PL의 최대값을 나타내는 파장의 이동은 관찰되지 않았다.