• Current Photovoltaic Research
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• 제3권1호
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• pp.27-31
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• 2015

It is known that sulfide at the $Cu(In,Ga)Se_2$ ($CIGSe_2$) surface plays a positive role in $CIGSe_2$ solar cells. We investigated the substitution of S with Se on the $CIGSe_2$ surface in S atmosphere. We observed that the sulfur content in the $CIGSe_2$ films changed according to sulfurization temperature and Cu/(In+Ga) ratio. The sulfur content in the $CIGSe_2$ films increased with increasing the annealing temperature and Cu/(In+Ga) ratio. Also Cu migration toward the surface increased at higher temperature. Since high Cu concentration at the $CIGSe_2$ surface is detrimental role, it is necessary to reduce the S annealing temperature as low as $200^{\circ}C$. The cell performance was improved at $200^{\circ}C$ sulfurization.

• 원예과학기술지
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• 제29권3호
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• pp.165-171
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• 2011

식물생장억제물질의 처리는 날개하늘나리의 줄기 신장을 억제시키는데, 여기에 관여하는 식물호르몬을 찾기 위해 diniconazole의 엽면살포 후 내생 GA 및 ABA의 함량 변화를 조사하였다. 그 결과, 날개하늘나리(L. dauricum)는 $GA_1$을 활성형으로 하는 early C-13 hydroxylation($GA_{19}{\rightarrow}GA_{20}{\rightarrow}GA_1$) 경로와 $GA_4$를 활성형으로 하는 non C-13 hydroxylation(NCH, $GA_{12}{\rightarrow}GA_{24}{\rightarrow}GA_9{\rightarrow}GA_4$) 경로 모두를 가지고 있었으나, 주된 경로는 NCH 경로였다. NCH 경로의 GA 생합성은 diniconazole $50mg{\cdot}L^{-1}$ 살포에 의해 초기 단계에서부터 억제되었다. 즉 diniconazole 처리구의 $GA_{12}$ 함량은 대조구에 비해 1/17로 현저히 감소되었으며, 이러한 경향은 $GA_4$까지 계속되었다. 즉 건물 1g당 $GA_{12}$ 함량은 대조구가 213.8ng인 것에 비해, diniconazole 처리구는 12.7ng이었다. ABA의 함량도 GA에서와 같이 diniconazole 살포에 의해 1/3 수준으로 크게 감소되었다. 즉 건물 1g당 ABA 함량은 대조구 37.2ng인 것에 비해, diniconazole 처리구는 14.8ng이었다. 본 연구의 결과, 내생 $GA_4$, $GA_1$, 그리고 ABA의 함량을 고려할 때 diniconazole에 의한 날개하늘나리의 초장감소는 $GA_4$의 생합성 억제에 기인한 것으로 생각된다.

• 약학회지
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• 제25권1호
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• pp.1-7
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• 1981

Glycyrrhizin (GA) content in licorice was determined by a couple of methods using HPLC, respectively. In Method(I), GA content itself was determined from the licorice aqueous extract, while in Method (II) glycyrrhetinic acid (GHeA ; the aglicone of GA) content corresponding to the quantity of GA was measured from the chloroform extract of the hydrolyzed product of licorice aqueous extract. A reverse phase column Hibar Lichrosorb RP-18 (E. Merck) was used as the stationary phase. As the mobile phase MeOH: $H_{2}O$(0.05M-$NaH_{2}PO_{4}$)=58 : 42 solution in Method (I), and MeOH: $H_{2}O $: AcOH=78; 19: 3 solution in Method (II) were suitable, respectively. The value obtained by Method (II) appeared slightly higher than that by Method (I). The effect of some other herbal drugs on the assay of GA quantity in mixed sample was also observed in both above two methods. By Method (I) Cassiae Cortex, Rehmaniae Rhizoma, Paeoniae Radix, and Angelicae Radix gave the subtractive effect on the amount of GA compared with the value from licorice alone. In the case of Method (II) Cassiae Cortex and Rehmaniae Rhizoma appeared to have subtractive effect but Paeoniae Radix and Angelicae Radix scarcely showed any influence. Pachymae Fungus did not affect the GA content at all. It seems that glycyrrhizin in licorice interacts with certain components of other herbal drugs.

• 반도체디스플레이기술학회지
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• 제10권3호
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• pp.29-33
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• 2011

Film growth rate and composition variation are numerically analyzed during the selective area growth of InGaN on the GaN triangular stripe microfacet in this study. Both the vapor phase diffusion and the surface diffusion are considered to determine the In composition on the InGaN surface. To obtain the In composition on the surface, flux of In atoms due to the surface diffusion is added to the concentration determined from the Laplace equation which is governing the gas phase diffusion. The solution model is validated by comparing the growth rates from the analyses to the experimental results of GaN and InN films. The In composition and resulting wave length are increased when the surface diffusion is considered. The In content is also increased according to the increasing mask width. The effect of mask width to the In content and wave length is increasing in the case of a small open region.

• JSTS:Journal of Semiconductor Technology and Science
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• 제1권2호
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• pp.111-115
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• 2001

Metamorphic InAlAs/InGaAs HEMT are successfully demonstrated, exhibiting several advantages over conventional P-HEMT on GaAs and LM-HEMT on InP substrate. The strain-relaxed metamorphic structure is grown by MBE on the GaAs substrate with the inverse-step graded InAlAs metamorphic buffer. The device with 40% indium content shows the better characteristics than the device with 53% indium content. The fabricated metamorphic HEMT with $0.2\mu\textrm{m}$T-gate and 40% indium content shows the excellent DC and microwave characteristics of $V_{th}-0.65V,{\;}g_{m,max}=620{\;}mS/mm,{\;}f_T120GHZ{\;}and{\;}f_{max}=210GHZ$.

• 한국재료학회지
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• 제20권8호
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• pp.434-438
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• 2010

The selenization process has been a promising method for low-cost and large-scale production of high quality CIGS film. However, there is the problem that most Ga in the CIGS film segregates near the Mo back contact. So the solar cell behaves like a $CuInSe_2$ and lacks the increased open-circuit voltage. In this study we investigated the Ga distribution in CIGS films by using the $Ga_2Se_3$ layer. The $Ga_2Se_3$ layer was applied on the Cu-In-Ga metal layer to increase Ga content at the surface of CIGS films and to restrict Ga diffusion to the CIGS/Mo interface with Ga and Se bonding. The layer made by thermal evaporation was showed to an amorphous $Ga_2Se_3$ layer in the result of AES depth profile, XPS and XRD measurement. As the thickness of $Ga_2Se_3$ layer increased, a small-grained CIGS film was developed and phase seperation was showed using SEM and XRD respectively. Ga distributions in CIGS films were investigated by means of AES depth profile. As a result, the [Ga]/[In+Ga] ratio was 0.2 at the surface and 0.5 near the CIGS/Mo interface when the $Ga_2Se_3$ thickness was 220 nm, suggesting that the $Ga_2Se_3$ layer on the top of metal layer is one of the possible methods for Ga redistribution and open circuit voltage increase.

• 한국재료학회지
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• 제34권4호
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• pp.185-193
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• 2024

In this study, NASICON-type Li_1+XGa_XTi_2-X(PO₄)₃ (x = 0.1, 0.3 and 0.4) solid-state electrolytes for all-solid-state batteries were synthesized through the sol-gel method. In addition, the influence on the ion conductivity of solid-state electrolytes when partially substituted for Ti⁴⁺ (0.61Å) site to Ga³⁺ (0.62Å) of trivalent cations was investigated. The obtained precursor was heat treated at 450 ℃, and a single crystalline phase of Li_1+XGa_XTi_2-X(PO₄)₃ systems was obtained at a calcination temperature above 650 ℃. Additionally, the calcinated powders were pelletized and sintered at temperatures from 800 ℃ to 1,000 ℃ at 100 ℃ intervals. The synthesized powder and sintered bodies of Li_1+XGa_XTi_2-X(PO₄)₃ were characterized using TG-DTA, XRD, XPS and FE-SEM. The ionic conduction properties as solid-state electrolytes were investigated by AC impedance. As a result, Li_1+XGa_XTi_2-X(PO₄)₃ was successfully produced in all cases. However, a GaPO₄ impurity was formed due to the high sintering temperatures and high Ga content. The crystallinity of Li_1+XGa_XTi_2-X(PO₄)₃ increased with the sintering temperature as evidenced by FE-SEM observations, which demonstrated that the edges of the larger cube-shaped grains become sharper with increases in the sintering temperature. In samples with high sintering temperatures at 1,000 ℃ and high Ga content above 0.3, coarsening of grains occurred. This resulted in the formation of many grain boundaries, leading to low sinterability. These two factors, the impurity and grain boundary, have an enormous impact on the properties of Li_1+XGa_XTi_2-X(PO₄)₃. The Li_1.3Ga_0.3Ti_1.7(PO₄)₃ pellet sintered at 900 ℃ was denser than those sintered at other conditions, showing the highest total ion conductivity of 7.66 × 10^-5 S/cm at room temperature. The total activation energy of Li-ion transport for the Li_1.3Ga_0.3Ti_1.7(PO₄)₃ solid-state electrolyte was estimated to be as low as 0.36 eV. Although the Li_1+XGa_XTi_2-X(PO₄)₃ sintered at 1,000 ℃ had a relatively high apparent density, it had less total ionic conductivity due to an increase in the grain-boundary resistance with coarse grains.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2003년도 추계학술발표강연 및 논문개요집
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• pp.22-22
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• 2003

Studies on the optical properties related to the built-in internal field and the carrier localization present in various GaN-based structures are essential not only for the physical interest but in designing practical visible and ultraviolet light emitting device applications with better performance and quantum efficiency. We report on the optical characteristics of various dimensional GaN-based structures such as (i) GaN self-assembled quantum dots grown in Stranski-Krastanov mode (OD), vertically-aligned GaN nanorods (1D), graded-In-content InGaN quantum wells (2D), laterally-overgrown GaN pyramids (3D), and GaN epilayers grown on various substrates. We used a wide variety of optical techniques, such as photoluminescence (PL), PL excitation, micro-PL, cathodoluminescence, optically-pumped stimulated emission, and time-resolved PL spectroscopy. An overview and comparison of the optical characteristics of the above GaN-based structures will be given.

• Current Photovoltaic Research
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• 제1권1호
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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.

• 한국재료학회지
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• 제2권5호
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• pp.360-365
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• 1992

Ga 첨가효과 및 Sputter 제조조건이 전기적 특성에 미치는 영향을 고찰하기 위해 ZnO분말과 G$a_2O_3$분말을 소결하여 타겟트를 제조하여 Sputter법으로 유리기판에 Ga-doped ZnO 다결정박막을 제조하였다. RF 전력밀도, 아르곤 개스압력 및 Ga 함유량등을 최적화한 후 제조한 투명한 Ga-doped ZnO 박막의 비저항은 1$0^{-3}$ohm-cm이며, undoped 및 Ga-doped ZnO 박막의 전자농도는 각 $10^{18}$, $10^{21}$/c$m^2$이였다. 공기와 질소분위기에서 열처리를 행하였을 때 Ga-doped ZnO 박막의 비저항은 $10^{2}$ order 증가하였다. 가시광영역의 투과율은 80% 이상이였으며, Ga 함유량이 증가하면 optical band gap도 넓어졌다.