• 한국전기전자재료학회논문지
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• 제30권11호
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• pp.717-721
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• 2017

We studied the performance enhancement of organic light-emitting diodes (OLEDs) using 2,3,5,6-fluoro-7,7,8,8-tetracyanoquinodimethane ($F_4-TCNQ$) as the hole-transport layer. To investigate how $F_4-TCNQ$ affects the device performance, we fabricated a reference device in an ITO (170 nm)/TPD(40 nm)/$Alq_3$(60 nm)/LiF(0.5 nm)/Al(100 nm) structure. Several types of test devices were manufactured by either doping the $F_4-TCNQ$ in the TPD layer or forming a separate $F_4-TCNQ$ layer between the ITO anode and TPD layer. N,N'-diphenyl-N,N'-di(m-tolyl)-benzidine (TPD), tri(8-hydroxyquinoline) aluminum ($Alq_3$), and $F_4-TCNQ$ layers were formed by thermal evaporation at a pressure of $10_{-6}$ torr. The deposition rate was $1.0-1.5{\AA}/s$ for TPD and $Alq_3$. The LiF was subsequently thermally evaporated at a deposition rate of $0.2{\AA}/s$. The performance of the OLEDs was considered with respect to the turn-on voltage, luminance, and current efficiency. It was found that the use of $F_4-TCNQ$ in OLEDs enhances the performance of the device. In particular, the use of a separate layer of $F_4-TCNQ$ realizes better device performance than other types of OLEDs.

• 대한화학회지
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• 제43권3호
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• pp.315-320
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• 1999

고성능 전계발광(electroluminescent, EL) 소자에 사용되는 발광물질의 개발을 위하여 설계된 발광기능기의 분자구조는 비스스틸렌구조의 발광기능기에 전자주입과 수송을 위한 시안기와 정공주입과 수송을 위한 페닐아민기를 가진 구조이다. 위의 발광기능기로 구성 된 고분자물질, PU-BCN과 저분자물질, D-BCN을 합성하였다. PU-BCN과 D-BCN을 발광층으로 사용하여 만들어진 단층형 소자(SL)의 구조는 Indium-tin oxide(ITO)/발광층/MgAg이고, 적층형소자의 구조는 ITO/발광층/oxadiazole dehvative/MgAg, (DL-E)와 ITO/tri-phenylamine derivative/발광층/MgAg,(DL-H)의 두 종류이다. 동일한 발광기능기를 가진 고분자 발광물질, PU-BCN과 저분자발광물질, D-BCN은 전하주입과 수송성이 띄어난 물질로 평가되었으며, 두 발광물질들은 높은 전류밀도하에서 거의 동일한 발광특성을 보였다. 발광물질들의 최대 발광 피이크는 약 640 nm의 적색 발광영역에서 측정되었다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2005년도 추계학술대회 논문집 Vol.18
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• pp.260-261
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• 2005

The heterolayered thick/thin structure consisting of $Pb(Zr_{0.52}Ti_{0.48})O_3$ and $BaTiO_3(BT)$ were fabricated by a sol-gel process. PZT powders, prepared by the sol-gel method, were mixed with an organic vehicle and the PZT thick films were fabricated by the screen printing techniques on alumina substrate with Pt electrodes. The microstructural and dielectric characteristics of the stacked heterolayered PZT/BT/PZT films were investigated by varying the number of coating $BaTiO_3$ layers. The existence of a $BaTiO_3$ layer between the PZT thick films of the tri-layer $Pb(Zr_xTi_{1-x})O_3/BaTiO_3/Pb(Zr_xTi_{1-x})O_3$thick/thin/thick film can greatly improve the leakage current properties of the PZT thick films. The average thickness of a PZT(5248)/$BaTiO_3$ heterolayered thick/thin film was 25$\mu$m. The relative dielectric constant and dielectric loss of the PZT(5248)/$BaTiO_3$-3 heterolayered thin film coated three times were 1087 and 1.00% at 1[MHz].

• 한국진공학회:학술대회논문집
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• 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
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• pp.281.1-281.1
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• 2016

Transition metal dichalcogenides (TMDCs) are promising layered structure materials for next-generation nano electronic devices. Many investigation on the FET device using TMDCs channel material have been performed with some integrated approach. To use TMDCs for channel material of top-gate thin film transistor(TFT), the study on high-k dielectrics on TMDCs is necessary. However, uniform growth of atomic-layer-deposited high-k dielectric film on TMDCs is difficult, owing to the lack of dangling bonds and functional groups on TMDC's basal plane. We demonstrate the effect of remote oxygen plasma pretreatment of large area synthesized few-layer MoSe2 on the growth behavior of Al2O3, which were formed by atomic layer deposition (ALD) using tri-methylaluminum (TMA) metal precursors with water oxidant. We investigated uniformity of Al2O3 by Atomic force microscopy (AFM) and Scanning electron microscopy (SEM). Raman features of MoSe2 with remote plasma pretreatment time were obtained to confirm physical plasma damage. In addition, X-ray photoelectron spectroscopy (XPS) was measured to investigate the reaction between MoSe2 and oxygen atom after the remote O2 plasma pretreatment. Finally, we have uniform Al2O3 thin film on the MoSe2 by remote O2 plasma pretreatment before ALD. This study can provide interfacial engineering process to decrease the leakage current and to improve mobility of top-gate TFT much higher.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2004년도 하계학술대회 논문집 Vol.5 No.2
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• pp.1070-1073
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• 2004

In this study, Tri(1-phenylpyrazolato)iridium $(Ir(ppz)_3)$ was prepared for the pure blue phosphorescent dopant and various host materials were used for the appropriate energy alignment. Although the luminance was pure blue with the CIE coordinates of x = 0.158, y = 0.139, device efficiencies didn't improve yet. Instead of finding the proper host materials, the alteration of structure of OLEDs affected the improvement of electrical and optical characteristics of the devices. It was worthy that insertion the exciton formation zone with the host material between the emitting zone and the exciton blocking layer. The device with a structure of ITO/NPB/Ir(ppz)3 doped in CBP/CBP for the exciton formation zone/BCP/Liq/Al was fabricated and the characteristics were observed compared with the devices without the exciton formation zone. When CBP was used for the exciton formation zone, the device efficiency reached to over 0.25 cd/A. While the device used CBP only for the host showed the luminous efficiency of under 0.11 cd/A

• 한국세라믹학회지
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• 제43권11호
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• pp.715-723
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• 2006

Perovskite oxide materials are very important for the electronics industry, because they exhibit promising properties. With an interest in the obvious applications, significant effort has been invested in the growth of highly crystalline epitaxial perovskite oxide thin films in our laboratory. And the desired structure of films was formed to achieve excellent properties. $Y_1Ba_2Cu_3O_{7-x}$ (YBCO) superconducting thin films were simultaneously deposited on both sides of 3 inch wafer by inverted cylindrical sputtering. Values of microwave surface resistance R$_2$ (75 K, 145 GHz, 0 T) smaller than 100 m$\Omega$ were reached over the whole area of YBCO thin films by pre-seeded a self-template layer. For implementation of voltage tunable high-quality varactor, A tri-layer structured SrTiO$_3$ (STO) thin films with different tetragonal distortion degree was prepared in order to simultaneously achieve a large relative capacitance change and a small dielectric loss. Highly a-axis textured $Ba_{0.65}Sr_{0.35}TiO_3$ (BST65/35) thin films was grown on Pt/Ti/SiO$_2$/Si substrate for monolithic bolometers by introducing $Ba_{0.65}Sr_{0.35}RuO_3$ (BSR65/35) thin films as buffer layer. With the buffer layer, the leakage current density of BST65/35 thin films were greatly reduced, and the pyroelectric coefficient of $7.6\times10_{-7}$ C $cm^{-2}$ $K^{-1}$ was achieved at 6 V/$\mu$m bias and room temperature.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2009년도 하계학술대회 논문집
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• pp.275-276
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• 2009

We have studied physical properties of organic light-emitting diodes (OLEDs) in a device with 7,7,8,8-tetracyanoquinodimethane (TCNQ). Since the TCNQ has a high electron affinity, it is widely used for a charge-transport and injection layer. And the TCNQ-derivatives have also been used to control the conductivity of the materials. It is known that a charge injection and transport in OLEDs with a TCNQ-derivative enhances a performance of the devices such as operating voltage and efficiency. To see how the TCNQ affects on the device performance, we have made a reference device in a structure of ITO(170nm)/TPD(40nm)/$Alq_3$(60nm)/LiF(0.5nm)/Al(100nm). And several type of devices were manufactured by doping TCNQ either in TPD or $Alq_3$ layer. The TCNQ layer was also formed in between the organic layers. N,N'-diphenyl-N,N'-di(m-tolyl)-benzidine (TPD), tri(8-hydroxy quinoline) aluminium ($Alq_3$), and TCNQ layers were formed by thermal evaporation at a pressure of $10^{-6}$ torr. The deposition rate was $1.0{\sim}1.5\;{\AA}/s$ for TPD, and $1.0{\sim}1.5\;{\AA}$ for $Alq_3$. The LiF was thermally evaporated at a deposition rate of $0.2\;{\AA}/s$ successively. The device with TCNQ-derivative improved the turn-on voltage compared to the one without TCNQ-derivative.

• Current Photovoltaic Research
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• 제2권4호
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• pp.147-151
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• 2014

A boron doping process using a boron tri-bromide ($BBr_3$) as a boron source was applied to form a $p^+$ emitter layer on an n-type mono-crystalline CZ substrate. Nitrogen ($N_2$) gas as an additive of the diffusion process was varied in order to study the variations in sheet resistance and the uniformity of doped layer. The flow rate of $N_2$ gas flow was changed in the range 3 slm~10 slm. The sheet resistance uniformity however was found to be variable with the variation of the $N_2$ flow rate. The optimal flow rate for $N_2$ gas was found to be 4 slm, resulting in a sheet resistance value of $50{\Omega}/sq$ and having a uniformity of less than 10%. The process temperature was also varied in order to study its influence on the sheet resistance and minority carrier lifetimes. A higher lifetime value of $1727.72{\mu}s$ was achieved for the emitter having $51.74{\Omega}/sq$ sheet resistances. The thickness of the boron rich layer (BRL) was found to increase with the increase in the process temperature and a decrease in the sheet resistance was observed with the increase in the process temperature. Furthermore, a passivated emitter solar cell (PESC) type solar cell structure comprised of a boron doped emitter and phosphorus doped back surface field (BSF) having Ni/Cu contacts yielding 15.32% efficiency is fabricated.

• 한국세라믹학회지
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• 제52권6호
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• pp.441-448
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• 2015

Silicon carbide (SiC) coatings for tri-isotropic (TRISO) nuclear fuel particles were fabricated using a chemical vapor deposition (CVD) process onto graphite. A micro-tensile-testing system was developed for the mechanical characterization of SiC coatings at high temperatures. The fracture strength of the SiC coatings was characterized by the developed micro-tensile test in the range of $25^{\circ}C$ to $1000^{\circ}C$. Two types of CVD-SiC films were prepared for the micro-tensile test. SiC-A exhibited a large grain size (0.4 ~ 0.6 m) and the [111] preferred orientation, while SiC-B had a small grain size (0.2 ~ 0.3 mm) and the [220] preferred orientation. Free silicon (Si) was co-deposited onto SiC-B, and stacking faults also existed in the SiC-B structure. The fracture strengths of the CVD-SiC coatings, as measured by the high-temperature micro-tensile test, decreased with the testing temperature. The high-temperature fracture strengths of CVD-SiC coatings were related to the microstructure and defects of the CVD-SiC coatings.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2017년도 추계 학술논문 발표대회
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• pp.139-140
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• 2017

This technology employs a method of forming a single-ply PLUS waterproofing sheet layer comprised of applying a single-ply synthetic polymer layer on a vibrating structure (steel frame, RC) or an inclined surface by using a T joint lap-filling coil and an embedded metal coated sheet. The T - joint reinforcing lap-filling coil was used to block the ingress channel of the rainwater by applying the material in the vulnerable area where the three sides of the waterproof sheet overlapped. Conventional waterproofing techniques have a problem in that the waterproof sheet is pierced because the end portion of the waterproof sheet applied to the vertical portion is fixed by a nail, and the sealant applied to the end portion of the sheet cannot easily secure long-term waterproof durability due to the influence of the external environment. Therefore, the developed technology secured the waterproof durability against the vertical part by using the embedded metal sheet. In addition, automatic hot-air fusing is used to improve the quality of waterproof construction and point fixation method using fixed hardware. This is a technology that is not significantly restricted in the high degradation level regions of domestic waterproof construction environments in Korea such as low-temperature environment, wet floor.