• 대한전자공학회논문지
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• 제14권3호
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• pp.6-11
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• 1977

GaAs Schottky Barrier Gate 전계효과트랜지스터의 잡음동작을 잡음등가회로를 사용하여 연구하였으며, 부가구인 잡음근원은 pinch-off영역에서 GaAs FET bias에 의하여 구현되었다. 이것이 바로 intervalley 산란잡음과 hot electron에 의한 잡음이었다. 본 논문의 잡음등가회로에서는 carrier의 포화속도와 기생저항의 영향을 고려한 parameter를 정하였다.

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 1997년도 춘계학술발표회논문집(2)
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• pp.401-406
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• 1997

This paper presents preliminary results on the degradation of BJTs(Bipolar Junction Transistors) and MOSFETs(Metal Oxide Semiconductor Field Effect Transistors) by 1MeV electron beam. Exposure experimental results show that the change of minority-carrier life time in base region dominates the behavior of BJTs and that the buildup of charges in oxide region can affect the value of threshold voltage for MOSFETs. It was possible to correlate the decrease of the minority-carrier life time of BJTs with irradiation dose, while the shift of MOSFETs' threshold voltage was not only a function of charge buildup in oxide region.

• 한국광학회:학술대회논문집
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• 한국광학회 2001년도 제12회 정기총회 및 01년도 동계학술발표회
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• pp.48-49
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• 2001

GaN는 wurzite structure를 갖는 wide bandgap III-V족 반도체로서, 청색 반도체 laser diode (LD), light emitting diode (LED)등으로 응용되는 물질이다. InGaN quantum well은 GaN계의 청색 LD, LED 구조에서 활성층으로 사용되기 때문에 이에 대한 광학적 연구가 활발하다. InGaN는 GaN위에 성장하면 strain에 의해 piezoelectric 효과가 크게 나타나는 것으로 알려져 있다. 이러한 piezoelectric potential에 의해 외부에서 voltage가 가해지지 않은 상황에서도 InGaN quantum well내의 electron, hole의 wave function이 비대칭 potential의 영향을 받게된다. (중략)

• 대한전자공학회논문지
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• 제5권1호
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• pp.1-5
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• 1968

GaAs의 단결정은 Ga의 용액으로부터 epitaxial 방법으로 성장시키는데 300°K에서는 carrier concentration 10 /㎤에서 electron-mobility 7,500∼9,300㎠/V-sec. 정도의 것이 얻어지며 77°K에서는 electron-mobility 50,000∼95,000㎠/V-sec.의 것이 얻어진다. mobility-온도 관계곡선의 이론적인 것과 실험적인 것을 비교해 보면 77°K에서 430°K의 온도범위내에서 ion화한 불순물과 phonon이 주요한 scattering mechanism이라는 것을 나타낸다. 이것은 epitaxial층이 mobility를 제한하는 다른 결함을 별로 내포하지 않는다는 것을 의미한다. epitaxial층의 photoluminescence spectra는 심부에 존재하는 결함의 준위에 의한 방출을 나타내지 않는다.

• 전자공학회논문지A
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• 제32A권6호
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• pp.59-66
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• 1995

The hot electron induced effective channel length modulation (${\Delta}L_{H}$) and HEIP characteristics in PMOSFET's after bidirectional stress are presented. Trapped electron charges in gate oxide and lateral field are calculated from the gate current model, and ${\Delta}L_{H}$(${\Delta}L_{HD},\;{\Delta}L_{HS}$) is calculated using trapped electron charges and lateral field. It has been found that ${\Delta}I_{d}$and ${\Delta}L_{H}$ are more affected by the stress order (Forward-Reverse of Reverse or Reverse-Forward) than the stress direction, and they vary logarithmically with the stress time. In contrast, ${\Delta}V_{t}$ and ${\Delta}V_{pt}$ are more affected by the stress direction thatn the stress order. The correlation between ${\Delta}V_{pt}$ and the stress time can be explanined as the following polynomial functin: ${\Delta}V_{pt}$=AT$^{n}$. It has also been shown that PMOSFET degradation is related with the gate current and the effects of ${\Delta}V_{pt}$ is the most significant.

• 폴리머
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• 제26권4호
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• pp.543-550
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• 2002

곁사슬에 정공 및 전자 전달체로 triphenylamine moiety와 triazine moiety를 갖는 새로운 공중합체를 합성하였다. ITO/공중합체와 발광물질 (DCM, coumarin 6, DPvBi)/Al으로 구성되는 단층형 유기 EL 소자는 정공 전달 단위체와 전자 전달 단위체 비율이 6:4와 방광물질의 함유량이 30 wt%일 때 최고의 외부 양자 효율을 나타내었다. 특히 위에서 제작한 유기 EL 소자는 각각 발광물질에 상응하는 빨강 (620 nm), 초록 (520 nm)과 파랑색 (450 nm)의 빛을 발광하였다. 최고 휘도는 DC 12V에서 ITO/공중합체 (6:4)와 DCM (30 wt%)/Al으로 구성되는 소자를 구동하였을 때 500 cd/$m^2$이었다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2015년도 제49회 하계 정기학술대회 초록집
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• pp.61.2-61.2
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• 2015

In the past decades, green energy, such as solar energy, wind power, hydropower, biomass energy, geothermal energy, and so on, has been widely investigated and developed to solve energy shortage. Recently, organic solar cells have attracted much attention, because they have many advantages, including low-cost, flexibility, light weight, and easy fabrication [1-3]. Organic solar cells are as a potential candidate of the next generation solar cells. In this abstract, to improve the power conversion efficiency and the stability, the inverted polymer solar cells with various structures were developed [4-6]. The novel cell structures included the P3HT:PCBM inverted polymer solar cells with AZO nanorods array, with pentacene-doped active layer, and with extra P3HT interfacial layer and PCBM interfacial layer. These three difference structures could respectively improve the performance of the P3HT:PCBM inverted polymer solar cells. For the inverted polymer solar cells with AZO nanorods array as the electronic transportation layer, by using the nanorod structure, the improvement of carrier collection and carrier extraction capabilities could be expected due to an increase in contact area between the nanorod array and the active layer. For the inverted polymer solar cells with pentacene-doped active layer, the hole-electron mobility in the active layer could be balanced by doping pentacene contents. The active layer with the balanced hole-electron mobility could reduce the carrier recombination in the active layers to enhance the photocurrent of the resulting inverted polymer solar cells. For the inverted polymer solar cells with extra P3HT and PCBM interfacial layers, the extra PCBM and P3HT interfacial layers could respectively improve the electron transport and hole transport. The extra PCBM interfacial layer served another function was that led more P3HT moving to the top side of the absorption layer, which reduced the non-continuous pathways of P3HT. It indicated that the recombination centers could be further reduced in the absorption layer. The extra P3HT interfacial layer could let the hole be more easily transported to the MoO3 hole transport layer. The high performance of the novel P3HT:PCBM inverted polymer solar cells with various structures were obtained.

• Journal of Microbiology and Biotechnology
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• 제27권3호
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• pp.500-506
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• 2017

To investigate the potential applications of bacterial heme, aminolevulinic acid synthase (HemA) was expressed in a Corynebacterium glutamicum HA strain that had been adaptively evolved against oxidative stress. The red pigment from the constructed strain was extracted and it exhibited the typical heme absorbance at 408 nm from the spectrum. To investigate the potential of this strain as an iron additive for swine, a prototype feed additive was manufactured in pilot scale by culturing the strain in a 5 ton fermenter followed by spray-drying the biomass with flour as an excipient (biomass: flour = 1:10 (w/w)). The 10% prototype additive along with regular feed was supplied to a pig, resulting in a 1.1 kg greater increase in weight gain with no diarrhea in 3 weeks as compared with that in a control pig that was fed an additive containing only flour. To verify if C. glutamicum-synthesized heme is a potential electron carrier, lactic acid bacteria were cultured under aerobic conditions with the extracted heme. The biomasses of the aerobically grown Lactococcus lactis, Lactobacillus rhamosus, and Lactobacillus casei were 97%, 15%, and 4% greater, respectively, than those under fermentative growth conditions. As a potential preservative, cultures of the four strains of lactic acid bacteria were stored at $4^{\circ}C$ with the extracted heme and living lactic acid bacterial cells were counted. There were more L. lactis and L. plantarum live cells when stored with heme, whereas L. rhamosus and L. casei showed no significant differences in live-cell numbers. The potential uses of the heme from C. glutamicum are further discussed.

• 한국재료학회지
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• 제23권9호
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• pp.517-524
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• 2013

The electrical and optical properties of fluorine-doped tin oxide films grown on polyethylene terephthalate film with a hardness of 3 using electron cyclotron resonance plasma with linear microwave of 2.45 GHz of high ionization energy were investigated. Fluorine-doped tin oxide films with a magnetic field of 875 Gauss and the highest resistance uniformity were obtained. In particular, the magnetic field could be controlled by varying the distribution in electron cyclotron deposition positions. The films were deposited at various gas flow rates of hydrogen and carrier gas of an organometallic source. The surface morphology, electrical resistivity, transmittance, and color in the visible range of the deposited film were examined using SEM, a four-point probe instrument, and a spectrophotometer. The electromagnetic field for electron cyclotron resonance condition was uniformly formed in at a position 16 cm from the center along the Z-axis. The plasma spatial distribution of magnetic current on the roll substrate surface in the film was considerably affected by the electron cyclotron systems. The relative resistance uniformity of electrical properties was obtained in film prepared with a magnetic field in the current range of 180~200A. SEM images showing the surface morphologies of a film deposited on PET with a width of 50 cm revealed that the grains were uniformly distributed with sizes in the range of 2~7 nm. In our experimental range, the electrical resistivity of film was able to observe from $1.0{\times}10^{-2}$ to $1.0{\times}10^{-1}{\Omega}cm$ where optical transmittance at 550 nm was 87~89 %. These properties were depended on the flow rate of the gas, hydrogen and carrier gas of the organometallic source, respectively.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
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• pp.467.1-467.1
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• 2014

Quantum dots (QD) solar cells has received considerable attention due to their potential of improving the overall conversion efficiency by harvesting excess energy via multiple excitons generation (MEG). Although there have been many reports which show MEG phenomena by using optical measurement of quantum dots themselves, carrier multiplication in real QD photovoltaic devices has been sparsely reported due to difficulty in dissociation of excitons and charge collection. In this reports, heterojunction QD solar cells composed of PbS QD monolayer on highly crystalline $TiO_2$ thin films were fabricated by using Langmuir-Blodgett deposition technique to significantly reduce charge recombination at the interfaces between each QD. The PbS CQDs monolayer was characterized by using UV-vis, transmission electron microscopy (TEM) and atomic force microscopy (AFM). The internal quantum efficiency (IQE) for the monolayer QD solar cells was obtained by measurement of external quantum efficiency and determining light absorption efficiency of active layer. Carrier multiplication was observed by measuring IQE greater than 100% over threshold photon energy. Our findings demonstrate that monolayer QD solar cell structure is potentially capable of realizing highly efficient solar cells based on carrier multiplication.