• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.583-583
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• 2012

최근 석유 자원의 고갈로 인한 대체자원의 관심이 커지면서 박막 태양전지에 대한 연구가 활발히 진행되고 있다. 기존의 단일 박막 태양전지는 Shockley-Queisser limit인 40.7%가 변환 효율의 최대값으로 한계가 정해져있다. 이 한계를 넘기기 위하여 현재 여러 층의 박막을 쌓은 tandem 태양전지, 양자점을 이용한 태양전지, 그리고 중간밴드계 태양전지가 제시되고 있다. 중간 밴드계 태양전지는 이론적으로 변환 효율이 63.2%에 달하며 제조 공정이 매우 용이하다는 장점을 가지고 있다. 이중에 ZnSe는 에너지밴드갭이 상온에서 2.7 eV를 가지고 있는 물질로서 파란색 빛을 내는 발광소자로 각광을 받고 있고, 산소를 주입했을 경우에 p형이 되는 성질과 자연적으로 n 형인 성질로 인해 박막 태양전지로 응용성에 대한 관심이 커지고 있다. 산소나 질소를 주입했을 경우 페르미준위 근처에서 중간밴드가 형성되었다는 연구결과들은 ZnTe(O)나 GaNAs를 통하여 확인되었으나, 현재까지 ZnSe를 이용한 중간밴드 태양전지에 대한 연구결과들은 거의 없는 상태이다. 본 연구에서는 ZnSe를 다양한 기판 온도에서 펄스레이저 증착법을 이용하여 성장하였고 성장하는 동안 산소 노출조건을 조절하여 깊은준위 에너지밴드형성에 대한 연구를 진행하였다. 성장온도와 산소 노출량에 따른 깊은준위에 대한 변화를 관찰하기 위하여 photoluminescence 스펙트럼을 분석하였으며, 박막의 품질에 대해 조사하기 위하여 X-ray diffraction을 이용하였다.

• Nuclear Engineering and Technology
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• v.55 no.6
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• pp.2166-2171
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• 2023

In the present study, six silicone rubber doped by tellurium borate oxides were fabricated using the casting method. The densities of the fabricated silicon rubber-doped by tellurium borate oxides samples were measured using the Archimedes Method. Moreover, the linear attenuation coefficient of silicone rubber doped tellurium borate oxides samples was evaluated experimentally using the hyper pure germanium, and the recorded linear attenuation coefficient values were affirmed using the theoretical Phy-X program. The experimental measurements were performed using the narrow beam transmission method with radioactive isotopes Am-241, Cs-137, and Co-60 with energies of 59, 661, 1173, and 1332 keV. The linear attenuation coefficient values showed an enhancement by 4.73 times, 1.20 time, 1.17, time, and 1.17 time, respectively at gamma photon energies of 59, 661, 1173, and 1332 keV, when the TeO₂ concentration increased in the fabricated composites from 0 to 50 wt%. The enhancement of the linear attenuation coefficient values has a positive effect on the transmission rate values where the half-value thickness and transmission rate were decreased accompanied by an increase in the RPE.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.08a
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• pp.25-30
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• 2002

The ternary semiconducting compounds of the $A_{4}BX_{6}$(A=Cd, Zn, Hg; B=Si, Sn, Ge; X=S, Se, Te) type exhibit strong fluorescence and high photosensitivity in the visible and near infrared ranges, so these are supposed to be materials applicable to photoelectrical devices. These materials were synthesized and single crystals were first grown by Nitsche, who identified the crystal structure of the single crystals. In this paper. author describe the undoped and $Co^{2+}$-doped $Zn_{4}SnSe_{6}$ single crystals were grown by the chemical transport reaction(CTR) method using iodine of $6mg/cm^{3}$ as a transport agent. For the crystal. growth, the temperature gradient of the CTR furnace was kep at $700^{\circ}C$ for the source aone and at $820^{\circ}C$ for the growth zone for 7-days. It was found from the analysis of x-ray diffraction that undoped and $Co^{2+}$-doped $Zn_{4}SnSe_{6}$ compounds have a monoclinic structure. The optical absorption spectra obtained near the fundamental absorption edge showed that these compounds have a direct energy gaps. These temperature dependence of the optical energy gap were closely investigated over the temperature range 10[K]~300[K]

• Journal of the Korean Society of Radiology
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• v.6 no.1
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• pp.73-77
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• 2012

Recently, Interest to the photoconductor, which is used to flat form X-ray detector such as a-Se, $HgI_2$, PbO, CdTe, $PbI_2$ etc. is increasing. In this study, the film layer by using the photoconductive material with particle sedimentation was fabricated and evaluated. The quantization efficiency of the continuous X-ray with the 70 kVp energy bandwidth was analyzed by using the Monte Carlo simulation. With the results, the thickness of film with 64 % quantization efficiency was 180 ${\mu}m$ which is similar to the efficiency of 500 ${\mu}m$ a-Se film. And $HIg_2$ film has the high quantization efficiency of 74 % on 240 ${\mu}m$ thickness. The electrical characteristics of the 239 ${\mu}m$ $Hgl_2$ films produced by particle sedimentation were shown as very low dark current(under 10 $pA/mm^2$), and high sensitivity(19.8 mC/mR-sec) with 1 $V/{\mu}m$ input voltage. The SNR, which is influence to the contrast of X-ray image, was shown highly as 3,125 in low driving voltage on 0.8 $V/{\mu}m$. With the results of this study, the development of the low-cost, high-performance image detector with film could be possible by replacing the film produced by particle sedimentation instead to a-Se detector.

• Resources Recycling
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• v.8 no.4
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• pp.45-56
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• 1999

The purpose of tlus sludy was to preparc raw material powder for Mn-Zn iclrile, h m mined mill scale and fero-Mn, usins a co-spray roasting process The mill scale and ferra-Mn uscd in this raalins process was rcf~nedb y mesn-ns of a slxc~apl rxcss ~nvolvinm~a te~ialsc ontalning imp~u-ltleso r less than 100 pprn In this study an effeclive spray roaster system. wllich produces fme complex oxide powder, collects produccd ~owder.,m d prcvel~tse ~~llssiooifi HCI gas. was also manufactured. By means of spray~ngp urifcd raw malerial solu~lionl nln a manufacued high tcmpervture rumace. &-ferrite powder and a comnpleu o ~ d e powder of Fe,O; and M,x203 were manufactured. The chmcterlstics of the composllion. surface urca, and p'miicle size dismbulion or the produced powder were exmined. ptoduced powdcr was then ~ m e dwi tli ZnO powder. aid olher addilives of defined cornposnion, and Mn-Zn femite cares werc praiuccil by meuns of Sorlning and closely controlled sintering processes. The magpelic p~oprlieso f c olo~ss, initlal permeability. mauin~u~mnn agnehc flux. coz~civcr orcc and residual magnccic flux for the above cores we,= measured, and fmm Il~ase I-csulls the eflicacy of lhe co-spray roasling pncess to pl.ellare raw material powder lor Mn-Zn ferntc was established

• Korean Journal of Materials Research
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• v.9 no.5
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• pp.446-451
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• 1999

Surface of Polymethylmethacrylate (PMMA) was modified by ion assisted reaction in which ion beam of Ar or$ O_2$is irradiated on polymer in reaction gas environment. Ion beam energy was changed from 600 to 1000eV, and ion doses were varied from $5\times10^{14} ions/cm^2 to 1\times10^{17} ions/cm^2$. Contact angle and surface energy of modified PMMA were measured by contact angle micrometer using distilled water and formamide. In the case of $Ar^+$ ion irradiation only, the contact angle reduced from $68^{\circ} to $35^{\circ}$ and the surface energy was changed from 46 dyne/cm to 60 dyne/cm. The contact angle significantly decreased to $14^{\circ}$and the surface energy increased to 72 dyne/cm when the surface of PMMA was modified by oxygen ion irradiation in oxygen gas environment. Improvement of wettability results from the formation of new hydrophilic group which is identified as C-O chain by XPS analysis. Recovery of wettability in dry air and maintenance of it in water condition were explained in view of the formation of hydrophilic group.

• Proceedings of the Korean Vacuum Society Conference
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• 2015.08a
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• pp.170.1-170.1
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• 2015

안티모니 (Sb)를 기반으로 한 제2형 초격자 (Type II superlattice, T2SL)구조 적외선 검출기 연구는 2000년대 들어 Sb 계열의 화합물 반도체 성장 기술이 발전함에 따라 HgCdTe (MCT), InSb, 양자우물 적외선 검출기 (QWIP)를 대체할 수 있는 고성능의 양자형 적외선 검출 소재로 부상하였으며, 현재 전 세계적으로 활발한 연구가 진행되고 있다. 특히, 기존의 양자형 적외선 검출소자에 비해 전자의 유효질량이 상대적으로 커서 밴드 간의 투과전류가 줄어들 뿐만 아니라, 전자와 정공이 서로 다른 물질 영역에 분포하여 Auger 재결합률을 효과적으로 줄일 수 있어 상온 동작이 가능한 소재로 주목을 받고 있다. 또한, T2SL 구조는 초격자를 구성하는 물질의 두께나 조성 변화를 통한 밴드갭 변조가 용이하여 단파장에서 장파장 적외선에 이르는 광범위한 파장 대역에서 동작이 가능할 뿐만 아니라 구조적 변화를 통해 이중 대역을 동시에 검출 할 수 있는 차세대 적외선 열영상 소자로 알려져 있다. 본 연구에서는 분자선 에피택시(MBE)법을 이용하여 300 주기의 InAs/GaSb (10/10 ML) 제2형 초격자 구조를 성장하여 적외선 검출소자를 제작하였다. 제2형 초격자 구조를 구성하는 물질계에 p-type dopant인 Be을 이용하여 각각 도핑 농도가 다른 시료를 성장하였다. 이때 p-type 도핑 농도는 각각 $1/5/10{\times}10^{15}cm^{-3}$로 변화를 주었다. 성장된 시료의 구조적 특성 분석을 위해 고분해능 X선 회절 (High resolution X-ray diffraction, HRXRD)법을 이용하였으며, 초격자 한 주기의 두께가 6.2~6.4 nm 로 설계된 구조와 동일하게 성장됨을 확인 하였으며, 1차 위성피크의 반치폭은 30~80 arcsec로 우수한 결정성을 가짐을 확인하였다. 적외선 검출을 위한 $410{\times}410{\mu}m^2$ 크기의 단위 소자 공정을 진행하였으며 이때 적외선의 전면 입사를 위해 소자 위에 $300{\mu}m$의 윈도우 창을 제작하였다. 단위 소자의 측벽에는 표면 누설 전류가 흐르는데 이를 방지하기 위해서 표면보호막을 증착하였다. 적외선 검출 소자의 전기적 특성 평가를 위해 각각의 시료의 암전류 (dark current)와 파장별 반응 (spectral response)을 온도별로 측정하여 비교 및 분석하였다.

• Journal of Nutrition and Health
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• v.19 no.4
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• pp.246-254
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• 1986

Weanling female Sprague Dawley rats were fed d diets containing 22mg pyridoxine. BCI/kg diet (control diet) and l.2mg pyridoxine. BCI/kg diet (deficient diet). One control group and one defi­c dent group were fed their diet throughout growth, g gestation and lactation. After the pups were born and weaned, the deficient group was divided into two groups. One switched to control diet(supple­I mented group) and the other continued the same d deficient diet( deficient group) until 10 week -old. The liver mitochondrial and cytosolic asparate a aminotransferase activity and pyridoxal phosphate content were determined in offspring rats. The aspartate aminotransferase activities in both liver mito$\phi$ondrial and cytosolic fractions of den­d cient group were significantly lower than those of controls, but there were no significant differences between two groups after addition of 1O^{-4}M pyri­d do뼈I phosphate to the medium. By pyridoxine s supplementation after weaning, the reduced aspar­a tate aminotnmsferase activities were only partialy I restored to control levels. The pyridoxal phospha­t te content of deficient group in Iiver mitochondr­ial and cytosoIic fractions were alo significantly different from those of controls, but readily restored by dietary supplementation. These results suggest that there is a quantitative and a qualitative changes of aspartate amino trans­f ferase and pyridoxal phosphate in liver mitochon­d drial and cytosolic fraction by long-term pyrido­x xine deficiency and these reductions can partially recovered by dietary pyridoxine supplementation after weaning.