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  • 1
    Electronic Resource
    Electronic Resource
    Optical modeling of a-Si:H solar cells with rough interfaces: Effect of back contact and interface roughness (2000)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 88 (2000), S. 6436-6443 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: An approach to study the optical behavior of hydrogenated amorphous silicon solar cells with rough interfaces using computer modeling is presented. In this approach the descriptive haze parameters of a light scattering interface are related to the root mean square roughness of the interface. Using this approach we investigated the effect of front window contact roughness and back contact material on the optical properties of a single junction a-Si:H superstrate solar cell. The simulation results for a-Si:H solar cells with SnO2:F as a front contact and ideal Ag, ZnO/Ag, and Al/Ag as a back contact are shown. For cells with an absorber layer thickness of 150–600 nm the simulations demonstrate that the gain in photogenerated current density due to the use of a textured superstrate is around 2.3 mA cm−2 in comparison to solar cells with flat interfaces. The effect of the front and back contact roughness on the external quantum efficiency (QE) of the solar cell for different parts of the light spectrum was determined. The choice of the back contact strongly influences the QE and the absorption in the nonactive layers for the wavelengths above 650 nm. A practical Ag back contact can be successfully simulated by introducing a thin buffer layer between the n-type a-Si:H and Ag back contact, which has optical properties similar to Al, indicating that the actual reflection at the n-type a-Si:H/Ag interface is smaller than what is expected from the respective bulk optical parameters. In comparison to the practical Ag contact the QE of the cell can be strongly improved by using a ZnO layer at the Ag back contact or an ideal Ag contact. The photogenerated current densities for a solar cell with a 450 nm thick intrinsic a-Si:H layer with ZnO/Ag and ideal Ag are 16.7 and 17.3 mA cm−2, respectively, compared to 14.4 mA cm−2 for the practical Ag back contact. The effect of increasing the roughness of the contact interfaces was investigated for both superstrate and substrate types of solar cells. Increasing the roughness of the carrier electrode, i.e., the rough electrode on which the silicon cell structure is deposited, up to 35 nm leads to a strong increase in the photogenerated current density; for higher values of the interface roughness the photogenerated current density tends to saturate. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1324690
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  • 2
    Electronic Resource
    Electronic Resource
    Electrical and optical properties of plasma-deposited a-SiGe:H alloys: Role of growth temperature and postgrowth anneal (1996)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 80 (1996), S. 6496-6504 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Basic properties of hydrogenated amorphous silicon–germanium (a-SiGe:H) alloys deposited by plasma-enhanced chemical-vapor deposition were studied. We found that there is an optimal growth temperature in the range 250–280 °C. Infrared-absorption spectra measurements show that in this temperature range the alloys have optimal composition of hydrogen content and bonding, providing a minimum in dangling bond defect density Ns and a high photoconductivity σph. Growth at lower temperatures results in hydrogen-rich alloys with high Ns. Hydrogen in these alloys is mainly bonded as SiH2 and as clusters on internal voids. Growth at temperatures above the optimal value gives less deterioration of the properties of a-SiGe:H than the growth below this optimal temperature. We found two different dependencies of σph on Ns: in optimized alloys σph changes proportionally to N−1s and in low-temperature alloys σph decreases more steeply with N−1s due to a decrease in electron mobility. It is shown that annealing of a-SiGe:H causes a sharp increase in Ns starting at annealing temperatures about 20 °C below the temperature at which the alloy was grown. We observed a new phenomenon that during annealing Ns increases much more (by two orders of magnitude) than the photoconductivity decreases (only factor of 5). The entropy-based model was applied to explain this experimental phenomenon. We found that annealing shifted the centrum energy of the D+/0 dangling bond levels to the valence-band edge. The rate of electron recombination lowers due to this shift and the change in the effective electron capture crosssection of the defects, and therefore the decrease in σph is smaller than the increase in Ns. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.363640
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  • 3
    Electronic Resource
    Electronic Resource
    Hydrogenated amorphous silicon transverse junction solar cell (1998)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 72 (1998), S. 209-210 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: In this letter, we introduce a new thin film solar cell design on amorphous silicon, called the transverse junction solar cell. In this concept, the p-i-n junction is formed perpendicular to the surface. With conventional deposition and silicon device processing techniques test cells have been made with a conversion efficiency up to 5.2%±1.4% under standard AM1.5 illumination. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.120687
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  • 4
    Electronic Resource
    Electronic Resource
    Glucose Tolerance, Insulin Secretion, Plasma Lipid Fatty Acids, and the Hypolipidemic Effects of Fish Oil (1993)
    Oxford, UK : Blackwell Publishing Ltd
    Annals of the New York Academy of Sciences 683 (1993), S. 0 
    Details
    ISSN: 1749-6632
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Natural Sciences in General
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1749-6632.1993.tb35740.x
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  • 5
    Electronic Resource
    Electronic Resource
    Seasonal variations in RNA–DNA ratios and in indicators of feeding, reproduction, energy storage, and condition in a population of bluegill, Lepomis macrochirus Rafinesque (1981)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of fish biology 18 (1981), S. 0 
    Details
    ISSN: 1095-8649
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Liver and epaxial muscle RNA concentrations and RNA-DNA ratios (RNA/DNA) of bluegill Lepomis macrochirus from a central Tennessee lake were maximum in the spring, low during the summer, high again in the fall, and low during the winter. Liver-somatic indexes and DNA concentrations indicated that liver cell volume and energy storage varied seasonally and were lowest during late spring and summer. Seasonal variations in gonosomatic indexes were typical of this species, and RNA/DNA decreased as gonads matured during the spring. RNA/DNA and energy storage in the liver decreased during the major spawning season. Seasonal variations in food consumption may have effected seasonal growth and energy storage. However, a summer depression in RNA/DNA may have been more closely associated with the effects of thermal stratification and dissolved oxygen stress.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1095-8649.1981.tb03766.x
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  • 6
    Electronic Resource
    Electronic Resource
    Effects of dietary n-3 fatty acids on the composition of cholesteryl esters and triglycerides in plasma and liver perfusate of the rat
    Amsterdam : Elsevier
    Journal of Nutritional Biochemistry 1 (1990), S. 472-477 
    Details
    ISSN: 0955-2863
    Keywords: n-3 fatty acids ; plasma and liver perfusate lipids
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/0955-2863(90)90083-W
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  • 7
    Electronic Resource
    Electronic Resource
    Ontogeny of N-acetyltransferase activity rhythm in pineal gland of chick embryo
    Amsterdam : Elsevier
    Comparative Biochemistry and Physiology -- Part A: Physiology 97 (1990), S. 175-178 
    Details
    ISSN: 0300-9629
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1016/0300-9629(90)90166-P
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  • 8
    Electronic Resource
    Electronic Resource
    Effects of exogenous melatonin on some endocrine, behavioural and metabolic parameters in japanese quail Coturnix coturnix japonica
    Amsterdam : Elsevier
    Comparative Biochemistry and Physiology -- Part A: Physiology 105 (1993), S. 323-328 
    Details
    ISSN: 0300-9629
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1016/0300-9629(93)90215-P
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  • 9
    Electronic Resource
    Electronic Resource
    Development of melatonin rhythm in the pineal gland and eyes of chick embryo (1992)
    Springer
    Cellular and molecular life sciences 48 (1992), S. 765-768 
    Details
    ISSN: 1420-9071
    Keywords: Melatonin ; circadian rhythm ; embryo ; ontogeny
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract A melatonin rhythm was observed in the pineals of 18-day-old chick embryos incubated under a light-dark regime of 18∶6 h. A low pineal melatonin content was found during the light phase of the day. Concentrations started to increase 2 h after dark onset and reached maximum levels after 4 h of darkness. The amplitude of the pineal melatonin rhythm increased considerably after 2 days and night-time concentrations in 20-day-old embryos were more than 5 times higher than in 18-day-old ones. Significant day/night differences in melatonin production were found both in pineals and eyes. Exposure of eggs to 1 h of light during the dark period decreased the high melatonin concentrations in the eyes but not in the pineals of the 20-day-old chick embryo. The results suggest that in this precocial bird at least part of the circadian system may already operate during embryonic life.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02124299
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  • 10
    Electronic Resource
    Electronic Resource
    Regulation of rhythmic melatonin production in pineal cells of chick embryo by cyclic AMP (1998)
    Springer
    Cellular and molecular life sciences 54 (1998), S. 461-466 
    Details
    ISSN: 1420-9071
    Keywords: Key words. Chick embryo; circadian rhythms; cAMP; melatonin; forskolin; IBMX; pineal cells.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract. The pineal cells of chick embryos incubated in vitro exhibited a daily rhythm of melatonin synthesis under a 1212 lightdark (LD) cycle at the embryonic days 16 and 19. In order to elucidate whether cyclic adenosine monophosphate (cAMP) – a component of the melatonin generating system – is already at work in the embryonic period, we measured the effects of forskolin and isobuthylmethylxantine (IBMX) on melatonin production, cAMP efflux and accumulation. Forskolin (after 10, 20, 30, 45, 60 and 90 min of administration) and IBMX (6 h), when applied during the light phase of LD cycle, stimulated melatonin production and cAMP efflux and accumulation during the embryonic period (at days 16 and 19 of development). Our results suggest that the biochemical pathway involving cAMP, which controls melatonin production in the postnatal period, is developed before hatching and already on embryonic day 19 works in a way similar to that in post-hatched chicks. Differences in response to cAMP stimulation between 16- and 19-day-old pinealo cytes seem to be mostly quantitative.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s000180050174
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