• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.07a
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• pp.889-892
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• 2000

We have investigated the Pt doping effect on structural and electrochemical properties of amorphous vanadium oxide film, grown by radio frequency magnetron sputtering. Room temperature charge-discharge measurements based on a half-cell with a constant current clearly indicated that the Pt doping could improve the cyclibility of V$_2$O$_{5}$ cathode film. Using glancing angle x-ray diffraction (GXRD) and high resolution transmission electron microscopy (HRTEM) analysis, we found that the Pt doping with l0W r.f. power induce more random amorphous structure than undoped V$_2$O$_{5}$ film. As the r.f. power of Pt increases, large amount of Pt incorporates into amorphous V$_2$O$_{5}$ and makes PtOx microcrystalline phase in amorphous matrix. This result suggests that the semicondcuting PtOx microcrystalline phase in amorphous matrix lead to a drastically faded cyclibility of 50W Pt doped V$_2$O$_{5}$ cathode film. Possible explanations are given to describe the Pt doping effect on cyclibility of vanadium oxide cathode film.de film.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.13 no.9
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• pp.751-757
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• 2000

The r.f. power effect for Pt doping is investigated on structural and electrochemical properties of amorphous vanadium oxide(V$_2$O$_{5}$) film, grown by direct current (d.c.) magnetron sputtering. Room temperature charge-discharge measurements based on a half-cell with a constant current clearly indicated that the Pt doping could improve the cyclibility of V$_2$O$_{5}$ cathode film. Using glancing angle x-ray diffraction(GXRD) and high-resolution transmission electron microscopy (HRTEM) analysis, we found that the Pt doping with 10W r.f. power induces more random amorphous structure than undoped V$_2$O$_{5}$ film. As the r.f. power of Pt target increases. large amount of Pt atoms incorporates into the amorphous V$_2$O$_{5}$ film and makes $\alpha$-PtO$_2$microcrystalline phase in the amorphous V$_2$O$_{5}$ matrix. These results suggest that the semiconducting $\alpha$-PtO$_2$ microcrystalline phase in amorphous matrix lead to a drastically faded cyclibility of 50W Pt doped V$_2$O$_{5}$ cathode film. Possible explanations are given to describe the Pt doping effect on cyclibillity of the amorphous V$_2$O$_{5}$ cathode film battery. film battery.

• Journal of the Korean Ceramic Society
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• v.37 no.10
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• pp.968-974
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• 2000

Nb$_2$O$_{5}$와 MnO 첨가에 따른 Pb$_{0.6}$Sr$_{0.4}$TiO$_3$반도체 세라믹의 미세구조와 전기적 특성은 유전특성, I(current)-V(voltage) 측정, 그리고 복소 임피던스 측정 등을 이용하여 고찰하였다. Nb 도핑량이 0.4 mol% 이하인 경우 Nb 도핑량에 따라 전도성과 입성장은 증가되었으나 그 이상의 도핑량에서는 Sr이나 Pb 공공의 생성으로 인하여 전도성이 감소되고 입성장도 억제되는 것을 관찰할 수 있었다. 0.4 mol% Nb-doped Pb$_{0.6}$Sr$_{0.4}$TiO$_3$에 0.01 mol% MnO를 첨가한 경우 비저항비($ ho$$_{max}$/$\rho$/min/)가 $10^2$에서 $10^4$으로 크게 향상되었다. 그리고 전이 온도 주변에서 여러 개의 변곡점을 지니는 비옴성 거동이 발견되었다. 이와 같은 현상은 입계에 존재하는 Mn 이온이 부분적으로 편석되어 표면 전하의 보상 효과에 영향을 미치는 것이라고 사료된다.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.449-449
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• 2010

유기발광소자(organic light-emitting diodes, OLEDs)는 저공정비용, 경량화, 가용성 및 대면적화 등의 장점으로 조명 분야와 디스플레이 분야로의 응용 가능성으로 인해 크게 주목을 받아 왔다. 이러한 OLED 소자의 고효율, 고휘도 및 저소비전력 등을 구현하기 위해서는 전극으로부터 전하 주입 층으로 효율적인 전하 주입이 요구된다. 즉, 각 전극의 폐르미 준위로부터 전하 전도준위대로의 전하주입 장벽이 없어야 한다. 본 연구에서는 홀 주입장벽이 없는 정공주입 층으로 $MoO_x$(molybdenum oxide)가 도핑된 NPB(N, N'-diphenyl-N, N'-bis(1-naphthyl)-1,1'-biphenyl-4,4'-diamine) 층을 사용하여 hole-only 소자를 제작하고 전류-전압 특성을 통해 양극으로부터 홀주입 층으로의 hole-ohmic 특성을 고찰했다. 또한, 전자 주입장벽이 없는 전자주입 층으로 $C_{60}$(fullerene)/LiF(lithum fluoride)의 이종 층을 사용하여 electron-only 소자를 제작하고 음극으로부터 전자주입 층으로의 전자 ohmic 특성을 조사했다. 또한, 전극으로부터 전하주입 층으로 ohmic 특성을 더 자세히 이해하기 위하여 전하주입 층의 자외선 광방출 스펙트럼(ultraviolet photoemission spectra)을 조사했다. 한편, glass/ITO/$MoO_x$-doped NPB (x%: x=0,25, 50 및 75; 5nm)/NPB (63nm)/$Alq_3$ (37nm)/$C_{60}$ (5nm)/LiF (1nm)/Al (100nm)로 구성된 all-ohmic OLED 소자의 발광특성은 $MoO_x$의 도핑 농도가 25%이상일 때 최적의 특성을 보여줬다. 이러한 현상은 정공주입 층에서 p형 도핑 농도의 증가에 따른 정공 농도의 증가에 기인한다. 또한 $MoO_x$의 도핑 농도의 증가에 따라 정공주입 층의 new gap state와 전극의 페르미 준위의 pinning에 기인한다. 25%의 $MoO_x$을 가진 OLED소자는 7.2V의 낮은 전압에서 $58300 cd/m^2$의 높은 휘도를 보여줬다.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.193-193
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• 2013

실리콘 박막 태양전지는 광 흡수층에서 형성된 정공과 전자를 효과적으로 분리하기 위해 p형과 n형으로 도핑된 층을 형성하는 p-i-n구조를 갖게 된다. 이러한 도핑 층을 형성하기 위해 B2H6와 PH3와 같은 독성 가스를 사용하기 때문에, 공정 안정성과 환경적인 이슈가 대두된다. 또한 도핑은 추가적으로 실리콘 박막 태양전지의 안정화 효율을 지속적으로 저하시키는 요인이 된다. 이러한 문제점을 개선하기 위하여, 창층으로 MoO3, V2O5, WO3 등과 같이 높은 일함수를 갖는 전이금속 산화물을 사용하고, 광 흡수층으로 i-Si:H을, 후면 전극으로 낮은 일함수를 나타내는 LiF/Al을 사용하였다. 전이금속 산화물과 LiF/Al의 큰 일함수 차이에 의해서 흡수층인 i-Si:H 에서 생성된 캐리어들은 효과적으로 분리되고 수집이 된다. 금속 산화물은 스퍼터링 공정에 의하여 이루어졌으며, 스퍼터링 공정조건에 따라 산화도가 조절되며, 이러한 산화도에 따라 태양전지의 셀 특성이 결정된다. 도핑 층이 없는 새로운 형태의 실리콘 박막 태양전지는 기존 비정질 실리콘 박막 태양전지에 비해 높은 안정화 효율을 나타내며, 이는 도핑 층이 없기 때문에 기존 실리콘 박막 태양전지의 열화현상에 따른 효율저하가 발생하지 않는 장점을 지내고 있다.

• Journal of IKEEE
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• v.22 no.2
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• pp.427-431
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• 2018

This research was worked about $Ga_2O_3$ Epi wafer that was one of the mose wide band gap semiconductors to be used power semiconductor industry. This wafer was grown $5.3{\mu}m$ thickness on Sn doped $Ga_2O_3$ Substrate by HVPE(Hydride Vapor Phase Epitaxy). Generally, we can fabricate 600V class power semiconductor devices when the thickness of compoound power semiconductor is $5{\mu}m$. but in case of $Ga_2O_3$ Epi wafer, we can obtain over 1000V class. As a result of J-V measurment of the grown $Ga_2O_3$ Epi wafer, we obtain $2.9-7.7m{\Omega}{\cdot}cm^2$ on resistance. Specially, in case of reverse, we comfirmed a little leakage current when the reverse voltage is over 200V.

• 한국초전도학회:학술대회논문집
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• v.9
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• pp.256-259
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• 1999

The effects of Pr doping on structural and superconducting properties of (Pb$_{0.5}$V$_{0.5}$)Sr$_2$(Ca$_{1-x}$Pr$_x$)Cu$_2$O$_z$ have been studied. We have observed systematic variation of lattice parameters with increasing Pr content. A maximum Tc of about40 K has been observed in this system. The correlation between the crystal structure and superconductivity has been addressed.

• Journal of the Korean Electrochemical Society
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• v.5 no.1
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• pp.1-6
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• 2002

Silver doped vanadium pentoxides with a doping ratio Ag/V ranging from 0.03 to 0.11 were synthesized by sol-gel process, and $Li/Ag_xV_2O_5$ cell was investigated by the electrochemical methods. It appears to be amorphous layered material and entangled fibrous textures has been grown to form anisotropic corrugated fibrils. NMR measurements revealed that several different kinds of $Li^+$ ions exist in the lithium intercalated xerogel electrodes and the average cell potential was about 3.0V vs. $Li/Li^+$. The cell capacity of the silver doped $Ag_xV_2O_5$ xerogel cathodes was more than 359 mAh/g at discharge current 10mA/g and cycle efficiency $94\%$ was achieved.

• Korean Journal of Crystallography
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• v.12 no.2
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• pp.70-75
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• 2001

The purpose of this study is to investigate the effect of V₂O/sub 5/ addition on physical and magnetic properties of NiCuZn ferrite for multi-layer chip inductors. NiCuZn ferrite pastes doped with 0, 0.1, 0.3 and 0.5 wt% V₂O/sub 5/ were prepared and samples of ferrite sheets were prepared by the screen printing method. They were sintered at 870, 880, 890 and 900℃, and then their physical and magnetic properties were analyzed. After sintering at 870℃, the sintered density of the ferrite sheet doped with 0.5wt% V₂O/sub 5/ showed the highest value to 5.08g/cm³due to the best densification by the liquid phase sintering, while the microstructures of ferrite sheets doped with 0.1 and 0.3 wt% V₂O/sub 5/ showed and inhibited grain growth. Irrespective of the sintering temperature, the initial permeability of ferrite sheet doped with 0.5 wt% V₂O/sub 5/ was highest and after sintering beyond 880℃, the quality factor of 0.3 wt% V₂O/sub 5/-doped sample appeared to be highest.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.32 no.3
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• pp.229-233
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• 2019

Pure $BiFeO_3$ (BFO) and (Eu, V) co-doped $Bi_{0.9}Eu_{0.1}Fe_{0.975}V_{0.025}O_{3+{\delta}}$ (BEFVO) thin films were deposited on $Pt(111)/Ti/SiO_2/Si(100)$ substrates by chemical solution deposition. The effects of co-doping were observed by X-ray diffraction, Raman spectroscopy, and scanning electron microscopy (SEM). The electrical properties of the BEFVO thin film were improved as compared to those of the pure BFO thin film. The remnant polarization ($2P_r$) of the BEFVO thin film was approximately $26{\mu}C/cm^2$ at a maximum electric field of 1,190 kV/cm with a frequency of 1 kHz. The leakage current density of the co-doped BEFVO thin film ($4.81{\times}10^{-5}A/cm^2$ at 100 kV/cm) was two orders of magnitude lower than of that of the pure BFO thin film.