• Title, Summary, Keyword: $GA_{3}$

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Simulation of Optical Characteristics of 1.3 μm GaAs-Based GaAsSb/InGaAs and GaAsSb/InGaNAs Quantum Well Lasers for Optical Communication (광통신용 GaAs 기반 1.3 μm GaAsSb/InGaAs와 GaAsSb/InGaNAs 양자우물 레이저의 광학적특성 시뮬레이션)

  • Park, Seoung-Hwan
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.24 no.1
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    • pp.1-6
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    • 2011
  • Optical gain characteristics of $1.3{\mu}m$ type-II GaAsSb/InGaNAs/GaAs trilayer quantum well structures were studied using multi-band effective mass theory. The results were compared with those of $1.3{\mu}m$ GaAsSb/InGaNAs/GaAs trilayer quantum well structures. In the case of $1.3{\mu}m$ GaAsSb/InGaNAs/GaAs trilayer quantum well structure, the energy difference between the first two subbands in the valence band is smaller than that of $1.3{\mu}m$ GaAsSb/InGaNAs/GaAs trilayer quantum well structure. Also, $1.3{\mu}m$ GaAsSb/InGaNAs/GaAs trilayer quantum well structure shows larger optical gain than $1.3{\mu}m$ GaAsSb/InGaNAs/GaAs trilayer quantum well structure. This means that GaAsSb/InGaNAs/GaAs system is promising as long-wavelength optoelectronic devices for optical communication.

A Study on Correlation among Length Changes of Body Surface Total lines and Segment Lines -Changed Amount Caused by the Lower Limb Movements- (체표(體表)길이 변화(變化)의 상관성(相關性) 연구(硏究) - 다리(下肢) 동작(動作)에 따른 변화량(變化量)을 중심(中心)으로 -)

  • Cho, Sung Hee
    • Journal of the Korean Society of Clothing and Textiles
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    • v.17 no.4
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    • pp.622-637
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    • 1993
  • The Purposes of this study were to investigate the significant correlation among the length changes of body surface total lines and between the length changes of body surface total lines and those of component body surface segment lines, and to reveal anticipated relation among body surface length changes by the lower limb movement including all movement direction of hip joint, knee joint & ankle joint for the more functional clothing making & designing. 10 Crosswise & 5 lengthwise body surface total lines and 48 crosswise & 39 lengthwise body surface segment lines of 26 female college students aged from 18 to 24 years were measured directly on the body surface and analyzed by ANOYA & Multiple Comparison Test(Tukey), and the length changes of them were calculated as the difference of the mean length at Fl movement from the mean length at each movement and were analyzed by PEARSON CORRELATION. The results were as following : 1. Correlation among the length changes of body surface total lines (1) Correlation among the length changes of body surface total lines significantly changed by the movement ; 1) The more GA5 expanded, the more GA6 & GA7 each expanded, and the more GA18 expanded, the more GA1 & GA3 each expanded. 2) The more GA15 expanded, the less GA14 each contracted. 3) The more GA7 expanded, the larger GA17 contracted. 4) The more GA1 & GA18 expanded, the larger GA16 contracted, and the larger GM contracted, the less GA16 contracted. (2) Only GA7 and GA17(at F4) showed high (over r=0.7) correlation coefficient, But others' correlation coefficients were r=0.4~0.7. (3) Correlation coefficients among & between girth items and length items 1) Correlation coefficients among girth items were shown + ; between GA3 and GA4, GA5, GA8, between GA5 and GA6, GA7, GA9 each, between GA1 and GA6 and between GA4 and GA7. 2) Correlation coefficients among length items were shown + or - ; shown + between GA14 and GA15 and between GA17 and GA16 ; but Shown - Between GAlS and GA16. 3) Correlation coefficients between girth items and length items were mainly shown - : shown-between GA1 and GA16, GA17, between, GA4 and GA16, between GA6, GA7 each and GA17, between GA8 and GA18 ; but shown + between GA1, GA3 each and GA18 and between GA8 and GA14 were shown +. 2. Correlation between the length changes of body surface total lines and those of component body surface segment lines. (1) All correlation coefficients were + except A147 of GA14. (2) Correlation coefficient over r=0.7 was shown ; between GA3 and CB3, A35 each, between GA5 and A054, between GA6 and A63, between GA7 and A72, A74 each, between GA8 and A83, A84 each, between GA15 and A153, between GA16 and Al64, Al65 each, between GA18 and A189 : but was not shown between GA4, GA17 and it's component body surface segment lines each. (3) Characteristics of correlation between the length changes of body surface total lines and those of body surface segment lines ; 1) If significant correlation of body surface total lines were expansion parts, it's component body surface segment lines was also expansion segment and the otherwise were the same. But exception was shown between expansion line GA3 and A031 (at F4), between GA18 and AlS9 (at F6) and between GA14 and A147, so to speak GA3 & lines and GA14 was contraction total line oppositely A147 was expansion. 2) The more GA3, GAlS expanded, the less A031, A189 contracted. 3) The more GA14 contracted, the more A147 expanded. 4) All correlation except the above 2), 3), the more total lines (GA1, GA3, GA5, GA15, GA16, GA18) expanded, the more segment lines (A15, CB1, A31, A34, CB3, A52, A54, A153, A169, A181) expanded, or the larger total lines (GA14, GA16, GA17) contracted, the larger segment lines (A141, A142, A161, A164, A165, A172) contracted.

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Effect of Carrier Confinement and Optical Properties of Two-dimensional Electrons in Al0.3Ga0.7N/GaN and Al0.3Ga0.7N/GaN/Al0.15Ga0.85N/GaN Heterostructures (Al0.3Ga0.7N/GaN 및 Al0.3Ga0.7N/GaN/Al0.15Ga0.85N/GaN 이종접합 구조에서 운반자 구속 효과와 이차원 전자가스의 광학적 특성)

  • Kwack, H.S.;Lee, K.S.;Cho, H.E.;Lee, J.H.;Cho, Y.H.
    • Journal of the Korean Vacuum Society
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    • v.17 no.4
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    • pp.359-364
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    • 2008
  • We have investigated optical and structural properties of $Al_{0.3}Ga_{0.7}N$/GaN and $Al_{0.3}Ga_{0.7}N/GaN/Al_{0.15}Ga_{0.85}N/GaN$ heterostructures (HSs) grown by metal-organic chemical vapor deposition, by means of Hall measurement, high-resolution X-ray diffraction, and temperature- and excitation power-dependent photoluminescence (PL) spectroscopy. A strong GaN band edge emission and its longitudinal optical phonon replicas were observed for all the samples. At 10 K, a 2DEG-related PL peak located at ${\sim}\;3.445\;eV$ was observed for $Al_{0.3}Ga_{0.7}N$/GaN HS, while two 2DEG peaks at ${\sim}\;3.42$ and ${\sim}\;3.445\;eV$ were observed for $Al_{0.3}Ga_{0.7}N/GaN/Al_{0.15}Ga_{0.85}N/GaN$ HS due to the additional $Al_{0.15}Ga_{0.85}N$ layers. Moreover, the emission intensity of the 2DEG peak was higher in $Al_{0.3}Ga_{0.7}N/GaN/Al_{0.15}Ga_{0.85}N/GaN$ HS than in $Al_{0.3}Ga_{0.7}N$/GaN HS probably due to an effective confinement of the photo-excited holes by the additional $Al_{0.15}Ga_{0.85}N$ layers. The 2DEG-related emission intensity decreased with increasing temperature and disappeared at temperatures above 150 K. To investigate the origin of the new 2DEG peaks, the energy-band structure for multiple AlGaN/GaN HSs were simulated and compared with the experimental data. As a result, the observed high- and low-energy peaks of 2DEG can be attributed to the spatially-separated 2DEG emissions formed at different AlGaN/GaN heterointerfaces.

Synthesis and Characterization of Gallium Nitride Powders and Nanowires Using Ga(S2CNR2)3(R = CH3, C2H5) Complexes as New Precursors

  • Jung, Woo-Sik;Ra, Choon-Sup;Min, Bong-Ki
    • Bulletin of the Korean Chemical Society
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    • v.26 no.1
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    • pp.131-135
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    • 2005
  • Gallium nitride (GaN) powders and nanowires were prepared by using tris(N,N-dimethyldithiocarbamato)gallium(III) (Ga(DmDTC)$_3$) and tris(N,N-diethyldithiocarbamato)gallium(III) (Ga(DeDTC)$_3$) as new precursors. The GaN powders were obtained by reaction of the complexes with ammonia in the temperature ranging from 500 to 1100 ${^{\circ}C}$. The process of conversion of the complexes to GaN was monitored by their weight loss, XRD, and $^{71}$Ga magic-angle spinning (MAS) NMR spectroscopy. Most likely the complexes decompose to $\gamma$ -Ga$_2$S$_3$ and then turn into GaN via amorphous gallium thionitrides (GaS$_x$N$_y$). The reactivity of Ga(DmDTC)$_3$ with ammonia was a little higher than that of Ga(DeDTC)$_3$. Room-temperature photoluminescence spectra of asprepared GaN powders exhibited the band-edge emission of GaN at 363 nm. GaN nanowires were obtained by nitridation of as-ground $\gamma$ -Ga$_2$S$_3$ powders to GaN powders, followed by sublimation without using templates or catalysts.

Preparation of $Ga_2O_3:Eu^{3+}$ phosphors by homogeneous precipitation (균일침전법에 의한 $Ga_2O_3:Eu^{3+}$ 형광체의 제조)

  • 천민호;박인용;이종원;김선태
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.12 no.3
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    • pp.149-156
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    • 2002
  • Europium-activated $Ga_2O_3$ phosphor powders were prepared by homogeneous precipitation method. The resulting powders were characterized by means of TG/DTA, XRD, FT-IR and SEM, Two kinds of powders formed were the crystalline GaOOH and the amorphous-like $\gamma$-$Ga_2O_3$ phases. When the urea concentration was below 0,5 M, rod-like micrometer-sized GaOOH powders were formed. They were transformed via $\alpha$-$Ga_2O_3$ to $\beta$-$Ga_2O_3$ phases under heat treatment. On the other hand, the nanometer-sized $\gamma$-$Ga_2O_3$ powders were formed with urea concentrations higher than 1.0 M, and they were directly changed into $\beta$-$Ga_2O_3$.Photoluminescence (PL) spectra were observed at room temperature, and PL intensities of nanometer-sized $Ga_2O_3$ : $Eu^{3+}$ powders around 610 nm were higher than those of micrometer-sized ones.

Changes in Gibberellin Hydroxylase Activity during Seed Maturation of Phaseolus vulgaris L. I. $3{\beta}-Hydroxylase$ Converting $GA_{20}\;to\;GA_1$ (강낭콩 (Phaseolus vulgaris L.) 종자성숙에 따른 지베렐린 수산화효소 활성의 변화 I. $GA_{20}을\;GA_1$으로 변환시키는 $3{\beta}-Hydroxylase$)

  • 정상수
    • Journal of Plant Biology
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    • v.35 no.3
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    • pp.185-190
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    • 1992
  • Changes in activity of gibberellin $3{\beta}-hydroxylase$ which converts $[^3H]GA_{20}\;to\;GA_1$ were studied during seed maturation using partially purified enzyme preparations of two cultivars, Kentucky Wonder (normal) and Masterpiece (dwarf) of Phaseolus vulgaris. The specific activity of $3{\beta}-hydroxylase$ per seed reached maximum at 21 days after flowering and subsequently decreased during seed maturation in both cultivars. The ratios of conversion of $[17-^{13}C,\;^3H_2]GA_{20}\;to\;GA_1.\;GA_5,\;and\;GA_6$ by the same amount of $3{\beta}-hydroxylase$ were almost identical. Epoxidation of $GA_5\;to\;GA_6$ is also catalyzed by the partially purified $3{\beta}-hydroxylase$ preparation(Kobayashi et aI., 1991) and the conversion was inhibited by the substrates of $3{\beta}-hydroxylase$. These results suggest that the same enzyme might catalyze $3{\beta}-hydroxylase{\;}of{\;}GA_{20}\;to\;GA_1$ and epoxidation of $GA_5\;to\;GA_6$..

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Ga Distribution in Cu(In,Ga)Se2 Thin Film Prepared by Selenization of Co-Sputtered Cu-In-Ga Precursor with Ga2Se3 Layer (Ga2Se3 층을 Cu-In-Ga 전구체 위에 적용하여 제조된 Cu(In,Ga)Se2 박막의 Ga 분포 변화 연구)

  • Jung, Gwang-Sun;Shin, Young-Min;Cho, Yang-Hwi;Yun, Jae-Ho;Ahn, Byung-Tae
    • Korean Journal of Materials Research
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    • v.20 no.8
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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.

Purification and Characterization of Gibberellin $3Beta$-Hydroxylase from Immature Seeds of Phaseolus vulgaris (강낭콩미숙종자로부터 Gibberellin $3Beta$-Hydroxylase 정제 및 성질)

  • 곽상수
    • Proceedings of the Botanical Society of Korea Conference
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    • pp.133-148
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    • 1987
  • Gibberellin(GA) 3-$\beta$ hydroxylation is very important for the shoot elogation in the higher plants, since only 3$\beta$-hydryoxylated GAs promote shoot elogation in several plants. Fluctuation of 3$\beta$-hydryoxylase activity was examined during seed maturation using two cultivars of , P. vulgaris, Kentucky Wonder (normal) and Masterpiece (dwarf). Very immature seeds of both cultivars contain high level of 3$\beta$-hydroxylase activity (per mg protein). Both cultivars showed maximum of enzyme activity (per seed) in the middle of their maturation process. Gibberellin 3$\beta$-hydroxylase catalyzing the hydroxylation of GA20 to GA1 was purified 313-fold from very early immature seeds of P. vulgaris. Crude soluble enzyme extracts were purified by 15% methanol precipitation, hydrophobic interaction chromatogrphy, DEAE ion exchange column chromatography and gel filtration HPLC. The 3$\beta$-hydroxylase activity was unstable and lost much of its activity duting the purification. The molecular weight of purified enzyme was extimated to be 42, 000 by gel filtration HPLC and SDS-PAGE. The enzyme exhibited maximum activity at pH 7.7. The Km values for [2.3-3H] GA20 and [2.3-3H]GA9 were 0.29 $\mu$M and 0.33 $\mu$M, respectively. The enzyme requires 2-oxoglutarate as a cosubstrate; the Km value for 2-oxoglutarate was 250 $\mu$M using 3H GA20 as a substrate. Fe2+ and ascorbate significantly activated the enzyme at all purification steps, while catalase and BSA activated the purified enzyme only. The enzyme was inhibited by divalent cations Mn2+, Co2+, Ni2+, Cu2+, Zn2+, Cd2+ and Hg2+. Effects of several GAs and GA anaogues on the putrified 3$\beta$-hydroxylase were examined using [3H]GA9 and GA20 as a substrates. Among them, GA5, GA9, GA15, GA20 and GA44 inhibited the enzyme activity. [13C, 3H] GA20 was converted by the partially purified enzyme preparation to [13C, 3H]GA1, GA5 and GA6, which were identified by GC-MS, GA9 was converted only GA4, GA15 and GA44 were converted to GA37 and GA38, respectively. GA5 was epoxidized to GA6 by the preparation. This suggests that 3$\beta$-hydroxylation of GA20 and epoxidation of GA5 are catalyzed by the same enzyme in P, vulgaris.

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Properties of Beta-Ga2O3 Film from the Furnace Oxidation of Freestanding GaN (FS-GaN을 열산화하여 제작된 Beta-Ga2O3 박막의 특성)

  • Son, Hoki;Lee, YoungJin;Lee, Mijai;Kim, Jin-Ho;Jeon, Dae-Woo;Hwang, Jonghee;Lee, Hae-Yong
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.30 no.7
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    • pp.427-431
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    • 2017
  • In this paper, we discuss ${\beta}-Ga_2O_3$ thin films that have been grown on freestanding GaN (FS-GaN) using furnace oxidation. A GaN template was grown by horizontalhydride vapor phase epitaxy (HVPE), and FS-GaN was fabricated using the laser lift off (LLO) system. To obtain ${\beta}-Ga_2O_3$ thin film, FS-GaN was oxidized at $900{\sim}1,100^{\circ}C$. Surface and cross-section of prepared ${\beta}-Ga_2O_3$ thin films were observed by field emission scanning electron microscopy (FE-SEM). The single crystal FS-GaNs were changed to poly-crystal ${\beta}-Ga_2O_3$. The oxidized ${\beta}-Ga_2O_3$ thin film at $1,100^{\circ}C$ was peel off from FS-GaN. Next, oxidation of FS-GaNwas investigated for 0.5~12 hours with variation of the oxidation time. The thicknesses of ${\beta}-Ga_2O_3$ thin films were measured from 100 nm to 1,200 nm. Moreover, the 2-theta XRD result indicated that (-201), (-402), and (-603) peaks were confirmed. The intensity of peaks was increased with increased oxidation time. The ${\beta}-Ga_2O_3$ thin film was generated to oxidize FS-GaN.

Segregation Mode of Plant Height in Crosses of Rice Cultivars ⅩIV. Segregation of Culm Length and $GA_3$ Response in Crosses of Dwarf Cultivars (수도 품종간 교잡에 있어서 간장의 유전분리 ⅩIV. 단간 품종간 조합에 있어서 간장과 $GA_3$ 반응성의 분리)

  • ;Mun-Hue Heu
    • KOREAN JOURNAL OF CROP SCIENCE
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    • v.35 no.2
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    • pp.165-170
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    • 1990
  • In order to determine the relationship between dwarf gene and GA$_3$ response, three dwarf cultivars, Fukei 71, Seolak, and Tanginbozu, which were known to have d 50, d 47 and d 35 gene, respectively, were used as parents in this study. Three parents and their F$_1$ and F$_2$ generations were grown. Tillers of each plant were devided into two parts at 15 days after transplanting and was transplanted. One part of them was sprayed with GA$_3$ 50 ppm at booting stage. The internode length were measured at ripening stage in terms of GA$_3$ response. The internode was significantly elongated in Seolak and Tanginbozu, but not in Fukei 71. All F$_1$ plants of the crosses were tall, and their internode and culm were significantly elongated with the spraying of GA$_3$. Dwarf plants which are not responded to GA$_3$ were selected in the F$_2$'s of Seolak/Fukei 71 and Fukei 71/Tanginbozu crosses, and backcrossed to Fukei 71. All of these BC$_1$F$_1$ plants were uniform in the culm length and not responded to GA$_3$ treatment. The dwarf gene, d 50 of Fukei 71 seems to be closely associated with the facter of non-response to GA$_3$.

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