• 센서학회지
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• 제29권2호
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• pp.105-111
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• 2020

Interest and demand for hydrogen sensors are increasing in the field of H₂ leakage detection during storage/transport/use and detection of H₂ dissolved in transformer oil for safety issues as well as in the field of breath analysis for non-invasively diagnosing a number of disease states for a healthy life. In this study, various ZnO-based sensors were synthesized by controlling the reduction in crystallite size, decoration of Pt nanoparticles, doping of electron donating atoms, and doping of various atoms with different ionic radii. The sensing response of the various prepared ZnO-based nanoparticles and quantum dots (QDs) for 10 ppm H₂ was investigated. Among the samples, the smallest-sized (3.5 nm) In³⁺-doped ZnO QDs showed the best sensing response, which is superior to those in previously reported hydrogen sensors based on semiconducting metal oxides. The higher sensing response of In-doped ZnO QDs is attributed to the synergic effects of the increased number of oxygen vacancies, higher optical band gap, and larger specific surface area.

• 한국전기전자재료학회논문지
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• 제26권4호
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• pp.284-288
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• 2013

Power MOSFETs(Metal Oxide Semiconductor Field Effect Transistor) operate as energy control semiconductor switches. In order to reduce energy loss of the device during switch-on state, it is essential to increase its conductance. We have experimental results and explanations on the doping profile dependence of the electrical behavior of the vertical MOSFET. The device is fabricated as $8.25{\mu}m$ cell pitch and $4.25{\mu}m$ gate width. The performances of device with various p base doping concentration are compared at Vth from 1.77 V to 4.13 V. Also the effect of the cell structure on the on-resistance and breakdown voltage of the device are analyzed. The simulation results suggest that the device optimized for various applications can be further optimized at power device.

• 한국세라믹학회지
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• 제47권2호
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• pp.99-105
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• 2010

The electrical transport properties of mayenite ($Ca_{12}Al_{14}O_{33}$ or $12CaO{\cdot}7Al_2O_3$; mostly abbreviated as $C_{12}A_7$) can be controlled in a wide range by varying the oxygen deficiency: At high temperatures mayenite becomes either an oxygen solid electrolyte, a mixed ionic/electronic conductor or an inorganic electride with metal-like properties upon chemical reduction (removing oxygen). The underlying defect chemistry can be understood on the basis of a relatively simple model-despite the complex cage structure: A point defect model based on the assumption that the framework $[Ca_{12}Al_{14}O_{32}]^{2+}$ acts as a pseudo-donor describes well the high temperature transport properties. It accounts for the observed conductivity plateau at higher oxygen activities and also describes the experimentally observed oxygen activity dependence of the electronic conductivity with -1/4 slope at temperatures between 800 and $1000^{\circ}C$. Doping effects in mayenite are still not well explored, and we review briefly the existing data on doping by different elements. Hydration of mayenite plays a crucial role, as Mayenite is hygroscopic, which may be a major obstacle for technical applications.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2000년도 춘계종합학술대회
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• pp.470-473
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• 2000

지난 10여 년 동안 MOSFET는 전력감소, 도핑농도 증가, 캐리어 속도 증가를 위해서 많은 변화를 가져왔다. 이러한 변화를 받아들이기 위해서, 채널의 길이와 공급되어지는 전압이 감소해야만했으며, 그것으로 인해 소자가 더욱 작아지게 되었다. 그러므로 본 논문은 이러한 변화를 위해 채널의 길이와 전압에 의한 MOSFET 구조에서의 변화를 관찰하고, 드레인과 게이트 사이에서의 임팩트 이온화의 변화를 관찰하였다. 본 논문은 세 가지의 모델 즉, conventional MOSFET와 LDD(lightly doped drain) MOSFET, EPI MOSFET을 제시하였다. 게이트 길이는 0.15um, 0.075um을 사용하였고, 스케일링계수는 λ = 2를 사용하였다 스케일링방법은 Constant-Voltage 스케일링으로 하였고, TCAD를 사용하여, 스케일링에 의한 MOSFET의 특성과 임팩트 이온화, 전계를 비교 분석하였으며, 최적의 채널과 도필 농도에 대하여 분석하였다.

• 한국전기전자재료학회논문지
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• 제19권1호
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• pp.1-6
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• 2006

High performance $Si_{0.8}Ge_{0.2}$ heterostructure metal-oxide-semiconductor field effect transistors (MOSFETs) were fabricated using well-controlled delta-doping of boron and $Si_{0.8}Ge_{0.2}$/Si heterostructure epitaxal layers grown by reduced pressure chemical vapor deposition. In this paper, we report 1/f noise characteristics of the SiGe pMOSFETs 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 $10^{-1}_10^{-2}$ in comparison 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.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2010년도 하계학술대회 논문집
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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.

• 한국정보통신학회논문지
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• 제13권6호
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• pp.1045-1050
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• 2009

본 연구에서는 MicroTec을 이용하여 태양전지의 전류-전압 특성곡선을 분석하였다. 전류-전압 특성곡선은 태양전지의 효율을 나타낸다. 전극이 직접 접촉하는 부분에 고농도 도핑을 하고 전극이 없는 부분에 저농도 도핑으로 전면을 처리한다. 도핑 농도를 $10^{14}cm^{-3}$에서 $10^{17}cm^{-3}$까지 변화시켜 도핑 농도에 따른 전류전압특성을 조사하였다. 또한 태양전지의 최대효율을 얻을 수 있는 도핑 농도를 결정하여 이의 전류-전압특성곡선을 비교 분석 하고자한다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 추계학술대회 논문집 Vol.15
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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.

• 한국반도체및디스플레이장비학회:학술대회논문집
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• 한국반도체및디스플레이장비학회 2002년도 추계학술대회 발표 논문집
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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.

• 한국세라믹학회지
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• 제52권5호
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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.