• 한국신재생에너지학회:학술대회논문집
• /
• 2009.06a
• /
• pp.138-138
• /
• 2009

Recently, thin-film solar cells of Cu(In,Ga)$Se_2$(CIGS) have reached a high level of performance, which has resulted in a 19.9%-efficient device. These conventional devices were typically fabricated using chemical bath deposited CdS buffer layer between the CIGS absorber layer and ZnO window layer. However, the short wavelength response of CIGS solar cell is limited by narrow CdS band gap of about 2.42 eV. Taking into consideration the environmental aspect, the toxic Cd element should be replaced by a different material. It is why during last decades many efforts have been provided to achieve high efficiency Cd-free CIGS solar cells. In order to alternate CdS buffer layer, ZnS buffer layer is grown by using chemical bath deposition(CBD) technique. The thickness and chemical composition of ZnS buffer layer can be conveniently by varying the CBD processing parameters. The processing parameters were optimized to match band gap of ZnS films to the solar spectrum and exclude the creation of morphology defects. Optimized ZnS buffer layer showed higher optical transmittance than conventional thick-CdS buffer layer at the short wavelength below ~520 nm. Then, chemically deposited ZnS buffer layer was applied to CIGS solar cell as a alternative for the standard CdS/CIGS device configuration. This CIGS solar cells were characterized by current-voltage and quantum efficiency measurement.

• Applied Biological Chemistry
• /
• v.33 no.2
• /
• pp.138-142
• /
• 1990

The effects of heavy metals Cd, Cu, Cr, Ni, and Zn on the degradation of the insecticide fenitrothion (O, O-dimethyl O-4-nitro-m-tolyl phosphorothioate), the fungicide IBP (5-benzyl O, O-diisopropyl phosphorothioate), and the herbicide butachlor (N-butoxymetyl-2-chloro-2', 6'-diethylacetanilide) in flooded soils were examined in the laboratory. The degradation of the 3 pesticides in soil was greatly inhibited by the amendment of the 5 heavy metals. The inhibition rate was high in the order of butachlor>IBP>fenitrothion. Populations of fenitrothion-and butachlor-degrading microbes, which were counted by the MPN method, were lower in heavy metals added soil than in the control soil. The effect of heavy metals on the degradation of the 3 pesticides in soil varied with the kind and concentration of heavy metals and the kind of pesticides.

• Journal of Animal Science and Technology
• /
• v.60 no.1
• /
• pp.29.1-29.6
• /
• 2018

Background: Dietary supplementation of zinc oxide (ZnO) to 2000 to 4000 mg/kg is known to be effective for the prevention and treatment of post-weaning diarrhea in the pig. Such a 'pharmacological' supplementation, however, can potentially result in environmental pollution of the heavy metal, because dietary ZnO is mostly excreted unabsorbed. Two experiments (Exp.) were performed in the present study to determine the effects of a lipid-coated ZnO supplement Shield Zn (SZ) compared with those of ZnO. Methods: In Exp. 1, a total of 240 21-day-old weanling pigs were fed a diet supplemented with 100 mg Zn/kg as ZnO (ZnO-100), ZnO-2500, SZ-100, or SZ-200 in 24 pens for 14 days on a farm with its post-weaning pigs exhibiting a low incidence of diarrhea. Exp. 2 was performed using 192 24-day-old piglets as in Exp. 1 on a different farm, which exhibited a high incidence of diarrhea. Results: In Exp. 1, fecal consistency (diarrhea) score (FCS) was less for the ZnO-2500 and SZ-200 groups than for the SZ-100 group (P < 0.05), with no difference between the SZ-100 and ZnO-100 groups. Both average daily gain (ADG) and gain:feed ratio were less for the SZ-200 group than for the ZnO-2500 group, with no difference between the ZnO-100 group and SZ-100 or SZ-200 group. The villus height (VH), crypt depth (CD), and VH:CD ratio of the intestinal mucosa were not influenced by the treatment. In Exp. 2, FCS was lowest for the ZnO-2500 group, with no difference among the other groups. However, neither the ADG nor gain:feed ratio was influenced by the treatment. Conclusion: Results suggest that physiological SZ supplementation has less beneficial effects than pharmacological ZnO for the alleviation of diarrhea irrespective of its severity and for promoting growth without influencing their integrity of the intestinal mucosal structures with little advantage over physiological ZnO in weanling pigs with a small pen size.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2015.08a
• /
• pp.201.1-201.1
• /
• 2015

복합 유무기 혼합물을 사용하여 제작한 유기 쌍안정 메모리 소자는 저전력 소비, 고밀도 저장성, 높은 기계적 유연성, 저렴한 가격, 간단한 공정 과정 등의 장점들로 인하여 메모리 분야에서 많은 관심을 받고 있다. 그래핀 옥사이드층을 활용하여 만든 소자에 관한 연구는 이미 다양하게 진행되고 있으나, CdSe/ZnS 양자점을 활용한 메모리 소자에 관한 연구는 아직 많이 연구되고 있지 않다. 본 연구에서는 CdSe/ZnS 양자점을 그래핀 옥사이드에 내포한 유기 쌍안정 메모리 소자를 제작하여 메모리로써의 활용 가능성과 메커니즘을 확인하였다. Indium-tin-oxide (ITO) 기판을 세척한 후, CdSe/ZnS 양자점을 내포한 그래핀 옥사이드 층을 스핀코팅을 이용하여 1000 rpm, 3000 rpm, 1000 rpm으로 각각 3 s, 40 s, 3 s로 코팅한 후 핫플레이트에서 90oC로 30분 동안 열처리 한다. 이렇게 제작된 소자의 실온에서 전류-전압을 측정한 결과 높은 전도도와 낮은 전도도의 비율이 최대 [10]^3까지 나오는 것을 확인할 수 있었다. 투과전자 현미경 및 X선 광전자 분광법 측정결과 그래핀 옥사이드 층과 그 안에 내포된 양자점들의 유무를 확인할 수 있었다. 내구성을 측정한 결과 소자가 안정적이라는 것을 확인할 수 있었다.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2013.02a
• /
• pp.684-685
• /
• 2013

p-형 반도체인 Cu(In,Ga)$Se_2$ (CIGS) 광 흡수 층은 이보다 에너지 밴드 간격이 큰 n-형 반도체와 이종 접합을 형성한다. 흡수층과 윈도우층 사이의 결정구조 차이와 밴드갭 에너지 차이를 완화시키기 위해 버퍼층이 필요하다. 버퍼층을 형성하는 물질로 화학적 용액 성장법(Chemical Bath deposition)을 사용한 CdS가 많이 적용되어 왔으나 Cd의 유해성 및 습식 공정으로 인한 연속공정에 대한 어려움이 있다. 따라서 버퍼층을 Cd을 포함하지 않는 ZnS, $In_2S_3$, (Zn, Mg)O 등과 같은 물질로 대체하여 원자층 증착법(Atomic Layer Deposition), 펄스레이져증착법(Pulsed Laser Deposition), 스퍼터링(sputtering) 등과 같은 건식으로 성장시키는 연구가 활발히 진행되고 있다. 본 연구에서는 $ZnO_{1-x}S_x$ ($0.2{\leq}x{\leq}0.4$)를 반응성 스퍼터링으로 증착하여 큰 밴드갭 에너지와 높은 광투과율를 갖는 버퍼층을 제작하였다. CIGS 박막의 손상을 줄여주기 위하여 RF 파워는 240, 200, 150, 100 W로 변화시켰다. CIGS 태양전지의 I-V 측정 결과, RF 파워가 150 W일 때 10.7%의 가장 높은 변환 효율을 보였고, 150 W 이상에서는 파워가 증가할 때 단락전류는 감소하였으며 개방전압은 다소 증가하였다. 반면 100 W에서 단락전류는 다소 증가하는 것에 반해 개방 전압이 급격히 낮아졌다. 이것은 파워에 따라 결합되는 산소의 양이 다르기 때문으로 생각된다.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
• /
• v.7 no.4
• /
• pp.226-234
• /
• 2002

A sediment exposure experiment was conducted to investigate the influence of acid volatile sulfides (AVS) and simultaneously extracted metals (SEM) in sediments on the bioavailability and toxicity of Cd, Ni and Zn to a marine polychaetes Neanthes arenaceodentata. The test animals were exposed to contaminated sediments spiked by metal mixtures of Cd, Ni, Zn (0.5～15 $\mu$mol/g of total SEM) in low (～1 $\mu$mol/g), medium (～5 $\mu$mol/g) and high AVS series (～10 $\mu$mol/g) to determine bioaccumulation, mortality and individual growth rate in each treatment after 20 days. Cd and Zn bioaccumulation in test animals increased with increasing of overlying water (OW) concentration controlled by AVS. In contrast, Ni bioaccumulation increased with increase of SEM concentration. Mortalities and growth inhibitions of N. arenaceodentata observed in only treatments with ［SEM-AVS］>0, due to a high level of OW-Zn. With regard to the mortality, the 20-d LC5O value fur OW-Zn was 9.3(8.0$\pm$11.0) $\mu$M. The LOEC (Lowest Observed Effect Concentration) for Tissue-Zn was 7.8 $\mu$mol/g and the NOEC (No Observed Effect Concentration) was 6.2 $\mu$mol/g. Regarding the inhibition of individual growth rate, the LOEC fer Tissue-Zn was 5.9 $\mu$mol/g, and NOEC was 5.1 $\mu$mol/g. In this study, the toxicity of dissolved metals, especially for Zn, was overemphasized due to the reduced distribution coefficients (K$\_$d/s) of metals in the experimental sediments.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2008.06a
• /
• pp.73-73
• /
• 2008

일반적으로 청색 및 자외선 발광다이오드, 레이저 다이오드, UV 감지기 (detector)소자 등의 기술적인 중요성은 ZnO를 기반으로 하는 산화물 반도체와 함께 와이드 밴드갭 반도체 연구가 활발히 진행되고 있다. ZnO의 경우 밴드갭 엔지니어링을 위해 일반적으로 Cd과 Mg을 사용하고 있으며 특히, ZnO에 Mg을 첨가하여 MgZnO 화합물을 첨가할 경우 밴드갭을 3.3eV~7.8eV까지 증가 시킬 수 있고, MgZnO/ZnO 초격자 구조를 이용할 경우 자유 엑시톤 결합에너지를 100meV 이상까지 증가시킬 수 있는 장점을 가지고 있다. 그러나 MgO는 결정구조가 rocksalt 구조를 가지는 입방정 구조이기 때문에 Hexagonal 구조를 가진 ZnO에 첨가될 경우 고용도에 큰 제한을 가지게 된다. 이와 같은 문제점으로 인하여 밴드갭 엔지니어링 기술은 여전히 해결되지 않은 문제점으로 남아 있다. 본 실험에서는 RF 마그네트론 스퍼터링 방법으로 사파이어 기판위에 MgZnO/ZnO 박막을 co-sputtering 시켰다. Targer은 ZnO(99.999%) 와 MgO (99.999%) target을 사용하였고, 스퍼터링 가스는 아르곤과 산소가스를 2:1 비율로 혼합시켜 성장하였다. MgZnO 박막을 성장하기 전 ZnO 층을 ~500 두께로 성장 시켰다. RF-power는 ZnO target을 고정 시키고, MgO targe power를 변화시켜 Mg 농도를 조절 하였다. 실험 결과 MgO target power 가 증가 할수록 반치폭이 증가하고, c-plane을 따라 격자 상수가 감소하는 것을 확인 할 수 있고, UV emission peak intensity가 감소며 단파장쪽으로 blue shift 하고, activation energy 가 증가하는 것을 관찰 할 수 있었다.

• Journal of the Korea Organic Resources Recycling Association
• /
• v.22 no.2
• /
• pp.17-26
• /
• 2014

In this study, the adsorption efficiency of mixed heavy metals from an aqueous solution was examined using bentonite. The physical and chemical properties of bentonite was analyzed via scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FT-IR), Further, heavy metal adsorption was characterized using Freundlich and Langmuir equations. Equilibrium adsorption data were fitted well to the Langmuir model for bentonite. The adsorption uptake of heavy metals was high and followed the order $Pb^{2+}$ > $Cu^{2+}$ > $Cd^{2+}$ > $$Zn^{2+}{\sim_=}Ni^{2+}$$. The results also showed that adsorption uptake slightly increased as increasing pH from 6 to 10. The bentonite surface was observed viay SEM and FT-IR; Si-O and Si-O-Al were found to be the main functional groups by FT-IR analysis. From these results, the adsorption mechanisms of heavy metal were not only surface adsorption and ion exchange, but also surface precipitation. Thus, bentonite could be a useful adsorbent for treating heavy metal in aqueous solution.

• Korean Journal of Soil Science and Fertilizer
• /
• v.11 no.2
• /
• pp.119-126
• /
• 1979

Rice seeds, suweon 264, were germinated under 5 levels of toxic heavy metals, Cd(0, 0.05, 0.5, 5, 20ppm), Cu(0, 0.05, 0.5, 5, 20, ppm), Cr(0, 0.5, 1, 5, 10ppm), Ni(0, 0.5, 1, 5, 10ppm), Co(0, 0.5, 1, 5, 10ppm), Zn(0, 0.5, 5, 20, 40, ppm), Pb(0, 0.5, 5, 20, 40ppm) and Mn(0, 1, 10, 25, 50, ppm) in culture solution, and then grown with supplying culture solution contained respective concentrations. Germination and growth response to the toxic heavy metals were studied. Results obtained are as follows : 1) The germination injury of rice seeds by excess concentration of toxic heave metal in culture solution occured in Cd and Cu; below 0.05 ppm, Ni; below 0.5 ppm, Mn; below 1.0 ppm, Co and Cr; 0.5-1.0 ppm, and 0.5-5 ppm, Zn and Pb. Thereby, in the order of degrees of the elements toxicity to germination, they were arranged as follows : Cd>Cu>Ni>Co>Cr>Mn>Zn$$\geq_-$$Pb. 2) Toxic heavy metal concentrations in culture solution, which result in decreasing dry weight due to the injury of excess concentration of treated elements, were Cd: below 0.05 ppm, Ni, Cr and Co; below 0.5 ppm, Cu and Zn; 0.5-5 ppm, Pb; 5-20 ppm and Mn; 10-25 ppm. The order was Ni>Cd>Cr>Co>Cu$$\geq_-$$Zn>Pb>Mn. 3) The critical contents of Cd, Ni, Pb, Cu, Zn, Mn, and Co in dry matter, Which result in decreasing dry weight, were considered to be 0.05-15.5, 1.50-25.0, 24.0-28.0, 26.5-62.5, 470-645.0, 231.0-500.0 and below 15.0 ppm, respectively. 4) The contents of Cr, Co, Cd, Pb, Ni, Cu and Zn in dry matter by 0.5 ppm treatment concentration of each heavy metals was trace, 15.0, 17.5, 24.0, 25.0, 84.5 and 470.0 ppm, respectively. Thereby, in the order of each element to uptaked by rice seedlings, they were arranged as follow; Zn>Cu>Ni>Pb>Cd>Co>Cr. 5) The hazardous concentrations of root activity by toxic heavy metals in culture solution were Cd; below 0.05, Cu; 0.05-0.5, Cr; below 0.5, Ni; 0.5-1.0, Co; 0.5-1.0, Zn; above 0.5, Pb; 0.5-5.0 and Mn; 1.0-10.0 ppm. The hazardous degree of root activity by toxic heave metals was in the order of Cd>Cu>Cr>Zn>Ni>Co>Pb>Mn.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2013.08a
• /
• pp.208-208
• /
• 2013

ZnO는 직접천이형 반도체로 약 3.37 eV의 넓은 에너지 band-gap과 60 meV의 비교적 큰 엑시톤 결합 에너지를 가지고 있다. 또한 단결정 성장 가능과 투명성 등 많은 장점들로 인하여 GaN와 대체할 자외선 또는 청색 발광소자나 ITO를 대체할 투명전극 같은 광범위한 광전소자로 큰 주목을 받으며 연구되어 왔다. 이러한 ZnO는 다양한 물질들의 첨가를 통해 인위적으로 특성변화가 가능한데 Mg, Be, Cd 첨가를 통한 에너지 밴드갭의 확장과 수축, Al 첨가를 통한 전기전도성의 증가 등이 그 예이다. 최근에는 밴드갭 조절을 이용한 ZnO-ZnMgO와 같은 이종접합구조가 광소자 등의 응용을 목적으로 많은 연구가 이루어지고 있다. 더불어 나노선이나 나노막대 같은 1차원 구조를 갖는 ZnO 계열 반도체의 연구는 현재 큰 이슈가 되고 있는 나노 크기의 소자 개발에 매우 큰 적용 가능성을 가지고 있다. 우리는 수열합성법을 이용하여 hexagonal ZnO 나노막대를 성장하고 그 표면에 core-shell 형태의 $ZnO-Zn_{1-x}Mg_xO$ (x=0.084) 양자우물을 원자층증착법으로 증착하였다. 본 연구에서는 만들어진 ZnO 나노막대와 ZnO-ZnMgO 나노막대, core-shell ZnO-ZnMgO 양자우물 sample들의 저온(5 K) Photoluminescence 측정을 통하여 광학적 band 구조를 분석하였다. 실험적으로 의도된 양자우물 두께와 다른 실제 형성된 양자무물의 두께를 알아내기 위하여 2차원 hexagonal 양자우물 band 구조에서 self-consistent nonlinear Poisson-Schr$\"{o}$dinger 방정식 계산과 컴퓨터 시뮬레이션을 이용하였으며, 이 방법으로 계산된 값과 실험값의 비교를 통하여 실제 형성된 양자우물의 두께를 정량적으로 유출할 수 있었다.