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Characterization of lattice parameters gradient of Cu(In1-xGax)Se2 absorbing layer in thin-film solar cell by glancing incidence X-ray diffraction technique

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journal of Materials Science & Technology 2020年第16期47卷 193-201页

作者： Yong-Il kim Ki-Bok kim Miso kim Department of Nano Science University of Science and Technology217GajeongYuseongDaejeon34113Republic of Korea Korea Research Institute of Standards and Science 267GajeongYuseongDaejseon34113Republic of Korea

In or Ga gradients in the Cu(In1-xGax)Se2(CIGS)absorbing layer lead to change the lattice parameters of the absorbing layer,giving rise to the bandgap grading in the absorbing layer which is directly associated with the degree of absorbing ability of the CIGS solar *** tried to characterize the depth profile of the lattice parameters of the CIGS absorbing layer using a glancing incidence X-ray diffraction(GIXRD)technique,and then investigate the bandgap grading of the CIGS absorbing *** the glancing incident angle increased from 0.50 to 5.00°,the a and c lattice parameters of the CIGS absorbing layer gradually decreased from 5.7776(3)to 5.6905(2)?,and 11.3917(3)to 11.2114(2)?,*** depth profile of the lattice parameters as a function of the incident angle was consistent with vertical variation in the compositionof In or Ga with depth in the absorbing *** variation of the lattice parameters was due to the difference between the ionic radius of In and Ga co-occupying at the same crystallographic *** to the results of the depth profile of the refined parameters using GIXRD data,the bandgap of the CIGS absorber layer was graded over a range of 1.222-1.532 *** approach allows to determine the In or Ga gradients in the CIGS absorbing layer,and to nondestructively guess the bandgap depth profile through the refinement of the lattice parameters using GIXRD data on the assumption that the changes of the lattice parameters or unit-cell volume follow a good approximation to Vegard’s law.

关键词： Cu(In1-xGax)Se2 absorbing layer Depth profile Glancing incidence X-ray diffraction technique Bandgap grading Vegard’s law

Report of a Dicephalic Steppes Ratsnake (Elaphe dione) Collected in South Korea

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Asian Herpetological Research 2013年第3期4卷 182-186页

作者： Il-Hun kim ja-Kyeong kim jonathan j.FONG Daesik PARK Department of Biology Kangwon National University School of Biological Sciences Seoul National University Division of Science Education Kangwon National University

In this report, we describe morphological characteristics of a dicephalic Steppes Ratsnake （Elaphe dione） collected from the wild in 2011 in South Korea. The specimen has two heads and two long necks. Unlike normal individuals, the dicephalic snake has divided ventral scales under the necks of the bifurcated columns. The snout- vent length （SVL） and overall total length of the individual are shorter than those of normal snakes of the same age. Nevertheless, the counts of nine different scale types that are often used for classification are all within the ranges of normal individuals. As far as we know, this is the first detailed morphological description of a dicephalic E. dione in the scientific literature.

关键词： dicephalism morphology Steppes Ratsnake Elaphe dione

Plasma density measurement and downstream etching of silicon and silicon oxide in Ar/NF3 mixture remote plasma source

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Plasma Science and Technology 2019年第6期21卷 52-57页

作者： H j YEOM D H CHOI Y S LEE j H kim D j SEONG S j YOU H C LEE Korea Research Institute of Standards and Science(KRISS) Daejeon 34113 Republic of Korea Department of Physics Chungnam National University Daejeon 34134 Republic of Korea

In this study,plasma density measurements were performed near the plume region of the remote plasma source (RPS) in Ar/NF3 gas mixtures using a microwave cutoff *** measured plasma density is in the range of 1010-1011 cm-3 in the discharge conditions with RPS powers of 2-4 kw and gas pressures of 0.87-4 *** plasma density decreased with increasing gas pressures and RPS powers under various Ar/NF3 mixing *** decrease in the plasma density measured at the fixed measurement position (plume region) can be understood by the reduction of the electron energy relaxation length with increases in the gas pressures and mixing ratio of NF3/(Ar/NF3).we also performed downstream etching of silicon and silicon oxide films in this *** etch rate of the silicon films significantly increases while the silicon oxide is slightly etched with the gas pressures and *** was also found that the etch rate strongly depends on the wafer position on the processing chamber electrode,and that the etch selectivity reached 96-131 in the discharge conditions of RF powers (3730-4180 w) and gas pressures (3.6-4 Torr).

关键词： remote plasma source electron density cutoff probe downstream etch

Adaptively driven X-ray diffraction guided by machine learning for autonomous phase identification

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npj Computational Materials 2023年第1期9卷 2036-2043页

作者： Nathan j.Szymanski Christopher j.Bartel Yan Zeng Mouhamad Diallo Haegyeom kim Gerbrand Ceder Department of Materials Science&Engineering UC BerkeleyBerkeleyCA 94720USA Materials Sciences Division Lawrence Berkeley National LaboratoryBerkeleyCA 94720USA

Machine learning(ML)has become a valuable tool to assist and improve materials characterization,enabling automated interpretation of experimental results with techniques such as X-ray diffraction(XRD)and electron *** ML models are fast once trained,there is a key opportunity to bring interpretation in-line with experiments and make on-the-fly decisions to achieve optimal measurement effectiveness,which creates broad opportunities for rapid learning and information extraction from ***,we demonstrate such a capability with the development of autonomous and adaptive *** coupling an ML algorithm with a physical diffractometer,this method integrates diffraction and analysis such that early experimental information is leveraged to steer measurements toward features that improve the confidence of a model trained to identify crystalline *** validate the effectiveness of an adaptive approach by showing that ML-driven XRD can accurately detect trace amounts of materials in multi-phase mixtures with short measurement *** improved speed of phase detection also enables in situ identification of short-lived intermediate phases formed during solid-state reactions using a standard in-house *** findings showcase the advantages of in-line ML for materials characterization and point to the possibility of more general approaches for adaptive experimentation.

关键词： phase diffraction autonomous

A plant-based diet and hypertension

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journal of Geriatric Cardiology 2017年第5期14卷 327-330页

作者： Sarah Alexander Robert j Ostfeld Kathleen Allen kim A williams Rush University Medical Center Division of Cardiology Chicago IL USA Montefiore Medical Center Division of Cardiology Bronx NY USA New York University Department of Nutrition & Food Studies NY USA

Hypertension is an insidious, common, and deadly dis-ease, often detected incidentally at a routine doctor＇s visit orworkplace health screening. worldwide, it is estimated thatone billion people have hypertension and... 详细信息

关键词： Hypertension Vegan Vegetarian Plant-based diet

Estimation of premature forests in Georgia (USA) using *** Service FIA data and Landsat imagery

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journal of Forestry Research 2017年第6期28卷 1241-1252页

作者： Hojung kim Chris j. Cieszewski Roger C. Lowe warnell School of Forestry and Natural Resources University of Georgia 180 E. Green Street AthensGA 30602 USA

we used geographic information system applications and statistical analyses to classify young, premature forest areas in southeastern Georgia using combined data from Landsat TM 5 satellite imagery and ground inventory data. we defined premature stands as forests with trees up to 15 years old. we estimated the premature forest areas using three methods: maximum likelihood classification(MLC), regression analysis, and k-nearest neighbor(k NN)modeling. Overall accuracy(OA) of classifying the premature forest using MLC was 82% and the Kappa coefficient of agreement was 0.63, which was the highest among the methods that we have tested. The k NN approach ranked second in accuracy with OA of 61% and a Kappa coefficient of agreement of 0.22. Regression analysis yielded an OA of 57% and a Kappa coefficient of 0.14. we conclude that Landsat imagery can be effectively used for estimating premature forest areas in combination with image processing classifiers such as MLC.

关键词： Landsat Maximum likelihood classification Regression analysis k-nearest neighbor

Automated segmentation of optical coherence tomography images

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Chinese Optics Letters 2019年第1期17卷 66-71页

作者： C.Kharmyssov M.w.L.Ko j.R.kim School of Engineering Nazarbayev University The University of Hong Kong

we propose a fast and accurate automated algorithm to segment retinal pigment epithelium and internal limiting membrane layers from spectral domain optical coherence tomography(SDOCT) B-scan images. A hybrid algorithm, which combines intensity thresholding and graph-based algorithms, was used to process and analyze SDOCT radial scans(120 B scans) images obtained from twenty patients. The relative difference in position of the layers segmented by the proposed hybrid algorithm and by the clinical expert was 1.49% ± 0.01%. The processing time of the hybrid algorithm was 9.3 s for six B scans. Dice's coefficient of the hybrid algorithm was 96.7% ± 1.6%. The proposed hybrid algorithm for the segmentation of SDOCT images had good agreement with manual segmentation and reduced processing time.

关键词： Automated segmentation optical coherence tomography images

Luminescence characteristics of Dy^(3+) doped Gd_2O_3-CaO-SiO_2-B_2O_3 scintillating glasses

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journal of Rare Earths 2016年第6期34卷 583-589页

作者： j.Kaewkhao N.wantana S.Kaewjaeng S.Kothan H.j.kim Center of Excellence in Glass Technology and Materials Science (CEGM) Nakhon Pathom Rajabhat University Department of Radiologic Technology Faculty of Associated Medical Sciences Chiang Mai University Department of Physics Kyungpook National University

Glasses were prepared from the compositions of 25Gd_2O_3-10 CaO-10 SiO_2-（55–x）B_2O_3-xDy_2O_3（where x is 0.0 mol.%–1.0 mol.%） by the conventional melt-quenching technique at 1400 oC. The results demonstrated the increase in the glass density with respect to the increase in the doping concentrations of Dy_2O_3. Nine absorption bands were observed. The emission spectra of the developed glass showed two strong peaks at 577 nm（~4F_（9/2）→~6H_（13/2）） and 482 nm（~4F_（9/2）→~6H_（15/2））. The highest emission intensity was observed from the developed glass prepared at 0.4 mol.% of Dy_2O_3, as the efficient energy transfer took place from Gd^（3＋） to Dy^（3＋）. From the X-ray induced optical luminescence, the emission spectra were identical to those from PL measurements, but with the highest intensity observed from the glass quenched at 0.45 mol.% of Dy_2O_3. Finally, the integral scintillation efficiency of the developed glass was determined at 27% of that of the commercially available BGO crystal.

关键词： amorphous materials glasses oxides optical properties luminescence rare earths

A High Dielectric N-Type Small Molecular Acceptor Containing Oligoethyleneglycol Side-Chains for Organic Solar Cellst

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Chinese journal of Chemistry 2018年第3期36卷 199-205页

作者： Bomee jang Changyeon Lee Young woong Lee Donguk kim Mohammad Afsar Uddin Felix Sunjoo kim Bumjoon j. kim Han Young woo Department of Chemistry Korea University Seoul 02841 Republic of Korea Department of Chemical and Biornolecular Engineering Korea Advanced Institute of Science and Technology (KAIST) Daejeon 34141 Republic of Korea School of Chemical Engineering and Materials Science Chung-Ang UniversitySeoul 06974 Republic of Korea

we report a new small molecular acceptor, ITIC-OEG, which is based on indacenodithieno[3,2-b]thiophene and 1,1-（dicyanomethylene）-3- indanone including oligoethyleneglycol （OEG） side-chains. ITIC-OEG was found to have higher dielectric constant （ε1=5.6} than that of a reference molecule of ITIC with normal alkyl substituents （ε1=3.9）. The dielectric constant of medium influences significantly the exciton binding energy and the resulting charge separation and recombination. The optical, electrochemical and morphological properties of ITIC-OEG and its photovoltaic characteristics were investigated by blending with a semi-crystalline donor polymer, PPDT2FBT, with comparison to those of ITIC. ITIC-OEG shows more red-shifted absorption and stronger crystalline packing than ITIC. However, the lower photovoltaic performance （with 1.58% power conversion efficiency, PCE） was measured for PPDT2FBT-ITIC-OEG, compared to PPDT2FBT：ITIC （5..52% PCE）. The incompatibility between PPDT2FBT and ITIC-OEG （due to high hydrophilic nature of OEG chains） resulted in poor intermixing with large domain separation over 300 nm, showing inefficient charge separation and significant charge recombination. Therefore, to investigate the effect of dielectric constant of the materials on the charge separation and recombination, the blend morphology of the PPDT2FBT：ITIC-OEG should be optimized first by improving their miscibility and phase separation.

关键词： N-type small molecule dielectric constant morphology organic solar cells