• Current Photovoltaic Research
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• v.1 no.1
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• pp.38-43
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• 2013

$Cu(In,Ga)_3Se_5$ is a candidate material for the top cell of $Cu(In,Ga)Se_2$ tandem cells. This phase is often found at the surface of the $Cu(In,Ga)Se_2$ film during $Cu(In,Ga)Se_2$ cell fabrication, and plays a positive role in $Cu(In,Ga)Se_2$ cell performance. However, the exact properties of the $Cu(In,Ga)_3Se_5$ film have not been extensively studied yet. In this work, $Cu(In,Ga)_3Se_5$ films were fabricated on Mo-coated soda-lime glass substrates by a three-stage co-evaporation process. The Cu content in the film was controlled by varying the deposition time of each stage. X-ray diffraction and Raman spectroscopy analyses showed that, even though the stoichiometric Cu/(In+Ga) ratio is 0.25, $Cu(In,Ga)_3Se_5$ is easily formed in a wide range of Cu content as long as the Cu/(In+Ga) ratio is held below 0.5. The optical band gap of $Cu_{0.3}(In_{0.65}Ga_{0.35})_3Se_5$ composition was found to be 1.35eV. As the Cu/(In+Ga) ratio was decreased further below 0.5, the grain size became smaller and the band gap increased. Unlike the $Cu(In,Ga)Se_2$ solar cell, an external supply of Na with $Na_2S$ deposition further increased the cell efficiency of the $Cu(In,Ga)_3Se_5$ solar cell, indicating that more Na is necessary, in addition to the Na supply from the soda lime glass, to suppress deep level defects in the $Cu(In,Ga)_3Se_5$ film. The cell efficiency of $CdS/Cu(In,Ga)_3Se_5$ was improved from 8.8 to 11.2% by incorporating Na with $Na_2S$ deposition on the CIGS film. The fill factor was significantly improved by the Na incorporation, due to a decrease of deep-level defects.

• Current Photovoltaic Research
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• v.3 no.3
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• pp.85-90
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• 2015

Two-step processes for preparing $Cu(In,Ga)Se_2$ absorber layers consist of precursor layer formation and subsequent annealing in a Se-containing atmosphere. Among the various deposition methods for precursor layer, the nonvacuum (wet) processes have been spotlighted as alternatives to vacuum-based methods due to their potential to realize low-cost, scalable PV devices. However, due to its porous nature, the precursor layer deposited on Mo substrate by nonvacuum methods often suffers from thick $MoSe_2$ formation during selenization under a high Se vapor pressure. On the contrary, selenization under a low Se pressure to avoid $MoSe_2$ formation typically leads to low crystal quality of absorber films. Although TiN has been reported as a diffusion barrier against Se, the additional sputtering to deposit TiN layer may induce the complexity of fabrication process and nullify the advantages of nonvacuum deposition of absorber film. In this work, Mo oxide layers via thermal oxidation of Mo substrate have been explored as an alternative diffusion barrier. The morphology and phase evolution was examined as a function of oxidation temperature. The resulting Mo/Mo oxides double layers were employed as a back contact electrode for $CuInSe_2$ solar cells and were found to effectively suppress the formation of $MoSe_2$ layer.

• Journal of Animal Science and Technology
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• v.48 no.6
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• pp.897-906
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• 2006

This study was conducted to determine effects of different supplementation periods (2, 3 and 4 months) of spent composts of Se-enriched mushrooms (Se-SMC) on plasma glutathione peroxidase (GSH-Px) activity and selenium deposition of finishing Hanwoo steers for the optimal supplementing period determination in order to produce Se-fortified Hanwoo beef. In the present study, 30 Hanwoo steers were allotted to treatments in six groups of five steers per pen. Treatments were separated into control and Se-SMC for each supplementation period. Dietary selenium contents were 0.1 and 0.9 ppm for control and Se-SMC treatments, respectively. At the end of each supplementation period, steers by periods were slaughtered to collect hind leg and liver samples for their selenium analyses. Blood samples were taken to analyze whole blood Se concentration and plasma GSH-Px activity at the last day of each supplementation period. Dry matter intakes were unaffected by Se-SMC and supplementation periods. In addition, average daily gain was not different between control and Se-SMC treatments and among supplementation periods. There was no difference for total body weight gain between control and Se-SMC treatments within each supplementation period. The supplementation of Se-SMC significantly (P<0.001) increased whole blood Se concentration, but whole blood selenium concentration was not affected by the supplementation period. Furthermore, plasma GSH-Px activity showed similar trend as shown in the pattern of whole blood Se concentration, but no difference by supplementation periods was observed. Selenium contents in hind legs significantly (P<0.05) increased with increasing supplementation periods, and also they were significantly (P<0.001) higher for Se-SMC supplementation groups in comparison to controls. However, there was no difference for selenium contents of hind legs between three and four months supplementation. Selenium contents in livers tended to slightly increase with increasing supplementation periods with no significant difference, but they were significantly (P<0.01) higher for Se-SMC supplementation groups compared with controls within the same period. The results indicated that the optimal Se-SMC supplementation period for the selenium deposition in Hanwoo steers might be around two or three months when we considered selenium contents in hind legs and livers.

• Journal of the Korean Electrochemical Society
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• v.14 no.3
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• pp.145-151
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• 2011

ZnSe, as a II-VI compound semiconductor which has a wide band gap in the visible region is applicable to the various fields such as laser diode, display and solar cell. By using the electrochemical deposition method, ZnSe thin film was synthesized on the ITO glass substrate. The synthesis of ZnSe grains and their structure having zinc blende shape were verified through the analysis of XRD and SEM. UV spectrophotometric method determined the band gap as the value of 2.76 eV. Applying the DFT (Density Functional Theory) in the molecular dynamics, the band structure of ZnSe grains was analyzed. For ZnSe grains with zinc blende structure, the band structure and its density of state were simulated using LDA (Local Density Approximation), PBE (Perdew Burke Ernzerhof), and B3LYP (Becke, 3-parameter, Lee-Yang-Parr) functionals. Among the calculations of energy band gap upon each functional, the simulated one of 2.65 eV based on the B3LYP functional was mostly near by the experimental measurement.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.457-457
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• 2012

We presented plasma processing using a DC Arc Plasmatron for diamond deposition on Al2O3 ceramic substrates. Plasma surface treatments were conducted to improve deposition condition before processing for diamond deposition. The Al2O3 ceramic substrates deposited, $5{\times}15mm^2$, were investigated by Scanning Electron Microscopy (SEM), Fourier Transform Infrared Spectroscopy (FTIR) and X-ray Diffraction (XRD). Properties of diamond (111), (220) and (311) peaks were shown in XRD. We identified nanocrystalline diamond films on substrates. The results showed that deposition rate was approximately $2.2{\mu}m/h$ after plasma surface treatments. Comparing the above result with a common processing, deposition rate was improved. Also, the surface condition was improved more than a common processing for diamond deposition on Al2O3 ceramic substrates.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.382-382
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• 2012

CIGS thin films have received great attention as a promising material for solar cells due to their high absorption coefficient, appropriate bandgap, long-term stability, and low cost production. CIGS thin films are deposited by various methods such as co-evaporation, sputtering, spray pyrolysis and electro-deposition. The deposition technique is one of the most important processes in preparing CIGS thin film solar cells. Among these methods, co-evaporation is one of the best technique for obtaining high quality and stoichiometric CIGS films. However, co-evaporation method is known to be unsuitable for commercialization. The sputtering is known to be very effective and feasible process for mass production. In this study, CIGS thin films have prepared by rf magnetron sputtering using a $Cu(In_{1-x}Ga_x)Se_2$ single quaternary target without post deposition selenization. This process has been examined by the effects of deposition parameters on the structural and compositional properties of the films. In addition, we will explore the influences of substrate temperature and additional annealing treatment after deposition on the characteristics of CIGS thin films. The thickness of CIGS films will be measured by Tencor-P1 profiler. The crystalline properties and surface morphology of the films will be analyzed using X-ray diffraction and scanning electron microscopy, respectively. The optical properties of the films will be determined by UV-Visible spectroscopy. Electrical properties of the films will be measured using van der Pauw geometry and Hall effect measurement at room temperature using indium ohmic contacts.

• Proceedings of the Materials Research Society of Korea Conference
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• 2007.11a
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• pp.61.2-61.2
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• 2007

• Bulletin of the Korean Chemical Society
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• v.30 no.4
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• pp.853-856
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• 2009

Highly polycrystalline copper indium diselenide (CuInSe2, CIS) thin films were deposited on glass or ITO glass substrates by two-stage metal organic chemical vapor deposition (MOCVD) at relatively mild conditions, using Cuand In/Se-containing precursors. First, pure Cu thin film was prepared on glass or ITO glass substrates by using a single-source precursor, bis(ethylbutyrylacetate)copper(II) or bis(ethylisobutyrylacetato)copper(II). Second, on the resulting Cu films, tris(N,N-ethylbutyldiselenocarbamato)indium(III) was treated to produce CuInSe2 films by MOCVD method at 400 ${^{\circ}C}$. These precursors are very stable in ambient conditions. In our process, it was quite easy to obtain high quality CIS thin films with less impurities and uniform thickness. Also, it was found that it is easy to control the stoichiometric ratio of relevant elements on demands, leading to Cu or In rich CIS thin films. These CIS films were analyzed by XRD, SEM, EDX, and Near-IR spectroscopy. The optical band gap of the stoichiometric CIS films was about 1.06 eV, which is within an optimal range for harvesting solar radiation energy.

• Solar Energy
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• v.7 no.2
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• pp.7-13
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• 1987

Indium-Tin-Oxide (ITO)/Selenium heterojunction solar cells which fabricated by vacuum deposition technique and annealing process has been investigated. Prior to the Selenium deposition, a thin tellurium layer (about $10{\AA}$) was deposited onto the ITO layers to provide a sufficient mechanical bond between the Oxide and Selenium layers. The amorphous Selenium layer was deposited onto the Te-ITO layers, and then the crystallization of the amorphous Selenium was carried out using a hot plate at about $180^{\circ}C$ for 4 min. Efficient Selenium solar cells with conversion efficiency as high as 4.52% under AM1 condition has been fabricated in polycrystalline Selenium layer ($6{\mu}m$). The optimum data in manufacturing Se solar cell was listed in table.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.398.1-398.1
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• 2014

The $Cu_2ZnSnSe_4$ (CZTSe) thin films solar cell is one of the next generation candidates for photovoltaic materials as the absorber of thin film solar cells because it has optimal bandgap (Eg=1.0eV) and high absorption coefficient of $10^4cm^{-1}$ in the visible length region. More importantly, CZTSe consists of abundant and non-toxic elements, so researches on CZTSe thin film solar cells have been increasing significantly in recent years. CZTSe thin film has very similar structure and properties with the CIGS thin film by substituting In with Zn and Ga with Sn. In this study, As-deposited CZTSe thin films have been deposited onto soda lime glass (SLG) substrates at different deposition condition using Pulsed Laser Deposition (PLD) technique without post-annealing process. The effects of deposition conditions (deposition time, deposition temperature) onto the structural, compositional and optical properties of CZTSe thin films have been investigated, without experiencing selenization process. The XRD pattern shows that quaternary CZTSe films with a stannite single phase. The existence of (112), (204), (312), (008), (316) peaks indicates all films grew and crystallized as a stannite-type structure, which is in a good agreement with the diffraction pattern of CZTSe single crystal. All the films were observed to be polycrystalline in nature with a high (112) predominant orientation at $2{\theta}{\sim}26.8^{\circ}$. The carrier concentration, mobility, resistivity and optical band gap of CZTSe thin films depending on the deposition conditions. Average energy band gap of the CZTSe thin films is about 1.3 eV.