• Title/Summary/Keyword: doping component

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Effects of Isolation Oxide Structure on Base-Collector Capacitance (소자격리구조가 바이폴라 트랜지스터의 콜렉터 전기용량에 주는 영향)

  • Hang Geun Jeong
    • Journal of the Korean Institute of Telematics and Electronics A
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    • v.30A no.10
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    • pp.20-26
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    • 1993
  • The base-collector capacitance of an npn bipolar transistor in bipolar or BiCMOS technology has significant influence on the switching performances, and comprises pnjunction component and MOS component. Both components have complicated dependences on the isolation oxide structure, epitaxial doping density, and bias voltage. Analytical/empirical formulas for both components are derived in this paper for a generic isolation structure as a function of epitaxial doping density and bias voltage based on some theoretical understanding and two-dimensional device simulations. These formulas are useful in estimating the effect of device isoation schemes on the switching speed of bipolar transistors.

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Removal Efficiency of Harmful Substances in Side-stream Tobacco Smoke by the Doping Components of Commercial TiO2 Photocatalysts (시판용 TiO2 광촉매의 doping 성분에 따른 비주류 담배연기의 유해물질 제거효율)

  • Kim, Tae-Young;Cho, Yeong-Tae;Moon, Gi-Hak;Kim, Jae-Yong
    • Applied Chemistry for Engineering
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    • v.28 no.5
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    • pp.565-570
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    • 2017
  • Tobacco smoke emitted during smoking is divided into a main-stream and side-stream smoke. Most of the tobacco smoke that spreads to a room while smoking is a side-stream one. The side-stream tobacco smoke is two to three times more harmful than that of the main-stream tobacco smoke. In this study, the removal efficiency of CO, $H_2S$, $NH_3$ and HCHO in a side-stream tobacco smoke using the doping component of $TiO_2$ photocatalysts was confirmed. As a result, CO was removed up to 78.37%, which indicated that the $TiO_2$ photocatalytic process is effective for CO removal. Also, the removal efficiencies of CO, $H_2S$ and HCHO were greatly affected by the amount of doped O and Si components of the $TiO_2$ photocatalyst. In conclusion, the more doped O and Si components had, the higher removal efficiencies of harmful substances were achieved.

Diffusion Behaviors of B and P at the Interfaces of Si/$SiO_2$ Multilayer System After the Annealing Process

  • Jang, Jong-Shik;Kang, Hee-Jae;Hwang, Hyun-Hye;Kim, Kyung-Joong
    • Proceedings of the Korean Vacuum Society Conference
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    • 2012.08a
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    • pp.232-232
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    • 2012
  • The doping of semiconducting elements is essential for the development of silicon quantum dot (QD) solar cells. Especially the doping elements should be activated by substitution at the crystalline sites in the crystalline silicon QDs. However, no analysis technique has been developed for the analysis of the activated dopants in silicon QDs in $SiO_2$ matrix. Secondary ion mass spectrometry (SIMS) is a powerful technique for the in-depth analysis of solid materials and the impurities analysis of boron and phosphorus in semiconductor materials. For the study of diffusion behaviour of B and P by SIMS, Si/$SiO_2$ multilayer films doped by B or P were fabricated and annealed at high temperatures for the activated doping of B and P. The distributions of doping elements were analyzed by SIMS. Boron found to be preferentially distributed in Si layer rather than the $SiO_2$ layer. Especially the B in the Si layers was separated to two components of an interfacial component and a central one. The central component was understood as the activated elements. On the other hand, phosphorus did not show any preferred diffusion.

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Tuning of the ferromagnetic transition by impurity doping in Ru$Sr_2$EuCe$Cu_2$$O_z$ (불순물 치환을 통한 Ru$Sr_2$EuCe$Cu_2$$O_z$ 계의 강자성 천이온도의 조절특성)

  • Lee H. K;Kim Y. H;Kwon O. H
    • Progress in Superconductivity
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    • v.6 no.1
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    • pp.37-40
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    • 2004
  • We investigated the effects of impurity doping on the electrical transport and magnetic properties of TEX>$(Ru, Sn)(Sr, La)<_2$$EuCeCu_2$$O_{z}$ samples. We found that Sn substitution fur Ru causes a significant decrease of the volume fraction of ferromagnetic phase, as well as a decrease of the temperature where the ferromagnetic component is observed. La substitution for Sr leads to an increase of the magnetic ordering temperature with a moderate change of ferromagnetic component. The experimental results are discussed in conjunction with the structural data, transport properties and a possible change of oxygen content.

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Poly-4-vinylphenol and Poly (melamine-co-formaldehyde)-based Tungsten Diselenide (WSe2) Doping Method

  • Nam, Hyo-Jik;Park, Hyung-Youl;Park, Jin-Hong
    • Proceedings of the Korean Vacuum Society Conference
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    • 2015.08a
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    • pp.194.1-194.1
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    • 2015
  • Transition metal dichalcogenide (TMD) with layered structure, has recently been considered as promising candidate for next-generation flexible electronic and optoelectronic devices because of its superior electrical, optical, and mechanical properties.[1] Scalability of thickness down to a monolayer and van der Waals expitaxial structure without surface dangling bonds (consequently, native oxides) make TMD-based thin film transistors (TFTs) that are immune to the short channel effect (SCE) and provide very high field effect mobility (${\sim}200cm^2/V-sec$ that is comparable to the universal mobility of Si), respectively.[2] In addition, an excellent photo-detector with a wide spectral range from ultraviolet (UV) to close infrared (IR) is achievable with using $WSe_2$, since its energy bandgap varies between 1.2 eV (bulk) and 1.8 eV (monolayer), depending on layer thickness.[3] However, one of the critical issues that hinders the successful integration of $WSe_2$ electronic and optoelectronic devices is the lack of a reliable and controllable doping method. Such a component is essential for inducing a shift in the Fermi level, which subsequently enables wide modulations of its electrical and optical properties. In this work, we demonstrate n-doping method for $WSe_2$ on poly-4-vinylphenol and poly (melamine-co-formaldehyde) (PVP/PMF) insulating layer and adjust the doping level of $WSe_2$ by controlling concentration of PMF in the PVP/PMF layer. We investigated the doping of $WSe_2$ by PVP/PMF layer in terms of electronic and optoelectronic devices using Raman spectroscopy, electrical measurements, and optical measurements.

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The Effects of Lithium-Incorporated on N-ZTO/P-SiC Heterojunction Diodes by Using a Solution Process (용액공정으로 제작한 리튬 도핑된 N-ZTO/P-SiC 이종접합 구조의 전기적 특성)

  • Lee, Hyun-Soo;Park, Sung-Joon;An, Jae-In;Cho, Seulki;Koo, Sang-Mo
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.31 no.4
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    • pp.203-207
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    • 2018
  • In this work, we investigate the effects of lithium doping on the electric performance of solution-processed n-type zinc tin oxide (ZTO)/p-type silicon carbide (SiC) heterojunction diode structures. The proper amount of lithium doping not only affects the carrier concentration and interface quality but also influences the temperature sensitivity of the series resistance and activation energy. We confirmed that the device characteristics vary with lithium doping at concentrations of 0, 10, and 20 wt%. In particular, the highest rectification ratio of $1.89{\times}107$ and the lowest trap density of $4.829{\times}1,022cm^{-2}$ were observed at 20 wt% of lithium doping. Devices at this doping level showed the best characteristics. As the temperature was increased, the series resistance value decreased. Additionally, the activation energy was observed to change with respect to the component acting on the trap. We have demonstrated that lithium doping is an effective way to obtain a higher performance ZTO-based diode.

Quantitative and Pattern Recognition Analyses for the Quality Evaluationof Herba Epimedii by HPLC

  • Nurul Islam, M.;Lee, Sang-Kyu;Jeong, Seo-Young;Kim, Dong-Hyun;Jin, Chang-Bae;Yoo, Hye-Hyun
    • Bulletin of the Korean Chemical Society
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    • v.30 no.1
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    • pp.137-144
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    • 2009
  • In this study, quantitative and pattern recognition analyses for the quality evaluation of Herba Epimedii using HPLC was developed. For quantitative analysis, five major bioactive constituents, hyperin, epimedin A, epimedin B, epimedin C, and icariin were determined. Analysis was carried out on Capcell pak $C_{18}$ column ($250{\time}4.6$ mm, 5 ${\mu}m$) with a mobile phase of mixture of acetonitrile and 0.1% formic acid, using UV detection at 270 nm. The linear behavior was observed over the investigated concentration range (2-50 ${\mu}g/mL;\;r_2\;>$ 0.99) for all analytes. The intraand inter-day precisions were lower than 4.3% (as a relative standard deviation, RSD) and accuracies between 95.1% and 104.4%. The HPLC analytical method for pattern recognition analysis was validated by repeated analysis of one reference sample. The RSD of intra- and inter-day variation of relative retention time (RRT) and relative peak area (RPA) of the 12 selected common peaks were below 0.8% and 4.7%, respectively. The developed methods were applied to analysis of twenty Herba Epimedii extract samples. Contents of hyperin, epimedin A, epimedin B, epimedin C, and icariin were calculated to be 0$\sim$0.79, 0.69$\sim$1.91, 0.93$\sim$9.58, 0.65$\sim$3.05, and 2.43$\sim$11.8 mg/g dried plant. Principal component analysis (PCA) showed that most samples were clustered together with the reference samples but several apart from the main cluster in the PC score plot, indicating differences in overall chemical composition between two clusters. The present study suggests that quantitative determination of marker compounds combined with pattern-recognition method can provide a comprehensive approach for the quality assessment of herbal medicines.

Study on the validity of PEAS for analyzing doping attitude and disposition of Korean elite player through Rasch model (엘리트 선수의 도핑 사고성향 분석을 위한 한국형 PEAS의 타당도 검증: Rasch 모형 적용)

  • Kim, Tae Gyu;Kim, Sae Hyung
    • Journal of the Korean Data and Information Science Society
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    • v.25 no.3
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    • pp.567-578
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    • 2014
  • PEAS (performance enhancement attitude scale) has been used to measure attitude and disposition toward doping in elite athlete. It is constructed of 17-item, 6-point scale. The purpose of this study was to verify validity of the PEAS for Korean elite player through Rasch model. The scale was administered to 438 Korean elite players. Principal component analysis was used to verify unidimensionality using SPSS program. Rasch measurement computer program, WISTEPS, was used to estimate goodness-of-fit of items and category structure. Differenctial item functioning by gender was also estimated by the WINSTEPS program. All alpha level was set at 0.05. First, principal component analysis showed that unidimensionality is satisfied as over 20.0% of variance of eigenvalue. Second, category probabilities curve showed 5-point scale was better than 6-point scaled statistically. Third, seven items (1, 9, 10, 12, 13, 14, 17) in the 17-item were not good model fit and three items (3, 12, 13) were estimated as the differential item functioning. This study showed that 9-item, 5-point scale is better PEAS to Korean elite player.

A Study on the High Frequency Properties of Mn-Zn ferrite with Re2O3(R=Dy, Gd, Ho) Addition (Re2O3(R=Dy, Gd, Ho)첨가에 따른 Mn-Zn ferrite의 고주파 특성에 관한 연구)

  • 최우성
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.16 no.6
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    • pp.538-548
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    • 2003
  • We studied effects by Re$_2$O$_3$(R=Dy, Gd, Ho) addition on the properties of Mn-Zn ferrite. The doping concentration range from 0.05 wt% to 0.25 wt%. All samples were prepared by standard fabrication of ceramics. With increasing the rare earth oxides, specific density and initial permeability increased on the whole. But, the tendencies such as upper result had the measured value on limitation and characteristics saturated or decreased properties after that. In case of excessive addition of additive beyond some level, initial permeability properties of ferrite have gone down in spite of anomalous grain. With increasing the content of additive, both the real and imaginary component of complex permeability and the magnetic loss (tan$\delta$) increased. Because the increased rate of real component had higher than imaginary component, magnetic loss increased none the less for increasing the real component related with magnetic permeability. But, the magnetic loss of ferrite doped with the rare earth oxides was lower than that of Mn-Zn ferrite at any rate. The small amount of present rare earth oxides in Mn-Zn ferrite composition led to enhancement of resistivity in bulk, and more so in the grain boundary. It was seem to be due to the formation of mutual reaction such as between iron ions and rare earth element ions.

Stability Improvement of CdTe Solar Cells using ZnTe:Na Back Contact (Na 도핑된 ZnTe 후면전극을 이용한 CdTe 태양전지의 안정성 개선에 관한 연구)

  • Cha, Eun Seok;Park, Kyu Charn;Ahn, Byung Tae
    • Current Photovoltaic Research
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    • v.3 no.1
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    • pp.10-15
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    • 2015
  • Cu doping by copper or $Cu_2Te$ materials enhances p+ formation in CdTe near the back contact interface, allowing better formation of ohmic contact. However, the Cu in CdTe junction is also considered as a principal component of CdTe cell degradation. In this paper, Na-doped ZnTe layer was employed as a back contact material to improve the stability of CdTe solar cells. As a process variable, post $CdCl_2$ treatment of CdS/CdTe film was conducted before or after depositing ZnTe:Na on CdTe. The change of the photovoltaic properties of CdTe cells were investigated with aging time. Low-temperature photoluminescence analysis was conducted to describe the degradation mechanism. The result showed that the CdTe solar cells with better stability compare to Cu contact were achieved using an optimized ZnTe:Na back contact.