• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2010.06a
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• pp.212-212
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• 2010

Recently, lithium transition metal phosphates with an ordered olivine-type structure, $LiMPO_4$ (M=Fe, Mn, Ni, and Co), have attracted extensive attention due to a high theoretical specific capacity (170 mAh/g). The $LiMPO_4$ is the most attractive because of its high stability, low cost, high compatibility with environment. However, it is difficult to attain its full capacity because its electronic conductivity is very low, and diffusion of Li-ion in the olivine structure is slow and the supervalue cation doping was used. In this research, we are used the supervalue cation doping methode such as Cu, Ti, and Mg were partially replace the Fe. The cycling performance resulted of the used $LiM_xFe_{1_x}PO_4$ cathode materials for lithium batteries exhibit excellent high capacity than $LiFePO_4$/Li cells.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.13 no.6
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• pp.1045-1050
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• 2009

The current-voltage characteristics of solar cell has been analyzed using MicroTec in this paper. The current-voltage characteristics represents a efficiency of solar cell. The part of metal contact is doped highly, but active region is doped lowly. We have investigated the current-voltage characteristics according to variation of doping concentration from $10^{14}cm^{-3}$ to $10^{17}cm^{-3}$. We has also determined the doping concentration to obtain the maximum efficiency of solar cell, and analyzed this current-voltage characteristics.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.11a
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• pp.43-46
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• 2002

Ferroelectric Mg-doped SBT and Ti-doped SBT were successfully deposited on Pt/Ti/$SiO_2/Si$ substrate by using a sol-gel solution coating method. The solutions were prepared through out adding the metal alkoxide solutions to SBT solution. The typical hysteresis loop of the films was obtained at 5V. The measured $2P_r$ value were $16.50{\mu}C/cm^2$ for SBT, $18.98{\mu}C/cm^2$ and for Mg-doped SBT, and $17.10{\mu}C/cm^2$ for Ti-doped SBT at an applied voltage of 5V, respectively. And it is found that the leakage current densities are less than $10^{-7}A/cm^2$ when applied voltage is less than 10.8MV/cm, which indicates the excellent insulating characteristics.

• Proceedings of the Korean Society Of Semiconductor Equipment Technology
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• 2002.11a
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• pp.81-84
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• 2002

The effects of the isoelectronic AI-doping of GaN grown by metal organic chemical vapor deposition were investigated for the first time using scanning electron microscopy (SEM), Hall measurements, photoluminescence (PL), and time-resolved PL. When a certain amount of Al was incorporated into the GaN films, the room temperature photoluminescence intensity of the films was approximately two orders larger than that of the undoped GaN. More importantly, the electron mobility significantly increased from 130 for the undoped sample to $500\textrm{cm}^2/Vs$ for the sample grown at a TMAl flow rate of $10{\mu}mol/min$, while the unintentional background concentration only increased slightly relative to the TMAl flow. The incorporation of Al as an isoelectronic dopant into GaN was easy during MOCVD growth and significantly improved the optical and electrical properties of the film. This was believed to result from a reduction in the dislocation-related non-radiative recombination centers or certain other defects due to the isoelectronic Al-doping.

• Journal of the Korean Ceramic Society
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• v.52 no.5
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• pp.331-337
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• 2015

$LaBO_3$ (B = Cr, Mn, Fe, Co, and Ni) perovskites, the most common perovskite-type mixed ionic-electronic conductors (MIECs), are promising candidates for intermediate-temperature solid oxide fuel cell (IT-SOFC) cathodes. The catalytic activity on MIEC-based cathodes is closely related to the bulk ionic conductivity. Doping B-site cations with other metals may be one way to enhance the ionic conductivity, which would also be sensitively influenced by the chemical composition of the dopants. Here, using density functional theory (DFT) calculations, we quantitatively assess the activation energies of bulk oxide ion diffusion in $LaBO_3$ perovskites with a wide range of combinations of B-site cations by calculating the oxygen vacancy formation and migration energies. Our results show that bulk oxide ion diffusion dominantly depends on oxygen vacancy formation energy rather than on the migration energy. As a result, we suggest that the late transition metal-based perovskites have relatively low oxygen vacancy formation energies, and thereby exhibit low activation energy barriers. Our results will provide useful insight into the design of new cathode materials with better performance.

• Journal of Satellite, Information and Communications
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• v.7 no.2
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• pp.18-24
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• 2012

High current behaviors of the extended drain n-type metal-oxide-semiconductor field effects transistor (EDNMOSFET) for electrostatic discharge (ESD) protection of high voltage operating LDI (LCD Driver IC) chip are analyzed. Both the transmission line pulse (TLP) data and the thermal incorporated 2-dimensional simulation analysis demonstrate a characteristic double snapback phenomenon after triggering of biploar junction transistor (BJT) operation. Also, background doping concentration (BDC) is proven to be a critical factor to affect the high current behavior of the EDNMOS devices. The EDNMOS device with low BDC suffers from strong snapback in the high current region, which results in poor ESD protection performance and high latchup risk. However, the strong snapback can be avoided in the EDNMOS device with high BDC. This implies that both the good ESD protection performance and the latchup immunity can be realized in terms of the EDNMOS by properly controlling its BDC.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.07a
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• pp.5-6
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• 2005

High performance SiGe heterostructure metal-oxide-semiconductor field effect transistors(MOSFETs) were fabricated using well-controlled delta-doping of boron and SiGe/Si heterostructure epitaxal layers grown by reduced pressure chemical vapor deposition. In this paper, we report 1/f noise characteristics of the SiGe MOSFETs measured under various bias conditions of the gate and drain voltages changing in linear operation regions. From the noise spectral density, we found that the gate and drain voltage dependence of the noise represented same features, as usually scaled with $f^1$. However, 1/f noise was found to be much lower in the device with boron delta-doped layer, by a factor of $10^{-1}\sim10^{-2}$ in comparion with the device fabricated without delta-doped layer. 1/f noise property of delta-doped device looks important because the device may replace bipolar transistors most commonly embedded in high-frequency oscillator circuits.

• 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.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.374.2-374.2
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• 2016

Volatile organic compounds (VOCs) in the atmosphere are harmful materials which influence indoor air environment and human health. Titanium dioxide ($TiO_2$) is photocatalyst extensively used in degradation of organic compound. To improve the photocatalytic activity in the visible light region, doping with non-metals element or loading noble metals on the surface of $TiO_2$ is generally proposed. In this study, N- doped $TiO_2$ having photocatalytic activity in visible light region was attached noble metal such as Pt, Ag, Pd, Au by coupling method. Catalytic activities of Noble metal coupled $N-TiO_2$ powders were evaluated by the improvement of their photocatalytic activities and the degradation of VOC gas. A UV-Vis spectrophotometer was used to measure the diffuse reflectance spectra of coupled $N-TiO_2$ sample. The photocatlytic activities of as prepared samples were characterized by the decoloration of aqueous MB solution under Xenon light source (UV and visible light). To measure of decomposition VOCs, ethylbenzene was selected for target VOC material and the concentration was monitored under UVLED irradiation in a closed chamber system. Adjusting the initial concentration of 10~12 ppm, to evaluate the removal characteristics by using the coupled $N-TiO_2$.

• Journal of Powder Materials
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• v.12 no.4 s.51
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• pp.266-272
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• 2005

Transition metal ions($Ni^{2+}$, $Cr^{3+}$ and $V^{5+}$) doped $TiO_2$ nanostructured powders were synthesized by mechanical alloying(MA) to shift the adsorption threshold into the visible light region. The synthesized powders were characterized by XRD, SEM, TEM and BET for structural analysis, UV-Vis and photoluminescence spectrum for the optical study. Also, photocatalytic abilities were evaluated by decomposition of 4-chlorophenol(4CP) under ultraviolet and visible light irradiations. Optical studies showed that the absorption wavelength of transition metal ions doped $TiO_2$ powders moved to visible light range, which was believed to be induced by the energy level change due to the doping. Among the prepared $TiO_2$ powders, $NiO^{2+}$ doped $TiO_2$ powders, showed excellent photooxidative ability in 4CP decomposition.