Library

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Electronic Resource
    Electronic Resource
    Wet thermal oxidation of AlxGa1−xAs compounds (1994)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 76 (1994), S. 5503-5507 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Results are presented on the wet thermal oxidation of AlxGa1−xAs. The growth of wet thermal oxides of AlxGa1−xAs is shown to be linear with time. An O2 carrier gas was found to form a self-terminating oxide for compositions investigated (x(approximately-greater-than)0.4), but required elevated temperatures for substantial growth. The use of a medium oxygen concentration (∼20%) in a N2 carrier formed nonuniform oxides for all compositions investigated. A low O2 concentration (0.1%) in the N2 carrier was found to reduce the activation energy of the oxidation process for Al0.6Ga0.4As from 1.9 to 1.0 eV while increasing the activation energy of Al0.8Ga0.2As from 1.6 to 1.75 eV. For these wet thermal oxides it is observed that lateral oxidation at heterojunction interfaces is enhanced. This enhanced lateral oxidation can be attributed to local stress due to the smaller volume of the growing oxide compared to the volume of the consumed semiconductor.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.357169
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    High-performance diffusion disordered AlxGa1−xAs lasers via a self-aligned process and conventional open-tube annealing (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 73 (1993), S. 2015-2018 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Process conditions for fabricating Si-O impurity-induced layer disorder defined AlxGa1−xAs-GaAs buried heterostructure quantum well lasers utilizing a fully self-aligned planar process and conventional As free open-tube-furnace annealing are presented. An SiO2 layer, deposited by sputtering, was used as a diffusion source for Si and O impurities as well as a source for Ga vacancies that enhance impurity diffusion and allow for a reduction in the required annealing temperature and time. A self-aligned native oxide of the AlxGa1−xAs cladding layer was used to form a Zn diffusion mask and dielectric layer. Lasers fabricated using this process exhibited threshold currents as low as 2.72 mA and external differential quantum efficiencies of 79% at room temperature in continuous operation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.353142
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Self-aligned native-oxide ridge-geometry AlxGa1−xAs-GaAs quantum well heterostructure laser arrays (1992)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 60 (1992), S. 1776-1778 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Process conditions for fabricating ridge geometry AlxGa1−xAs-GaAs quantum well heterostructure laser arrays utilizing a high quality self-aligned native oxide of AlxGa1−xAs are presented. Wet oxidation is performed, after etching ridges, via H2O vapor in a N2 or N2/H2(10%) carrier gas at 435–445 °C for 15–20 min. The formation of a uniform smooth oxide was found to be critically dependent on the crystal environment prior to the oxidation process. Characteristics of devices fabricated by this process are presented.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.107184
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    Mating system of the intertidal copepod Tigriopus californicus (1985)
    Springer
    Marine biology 86 (1985), S. 247-252 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Male Tigriopus californicus clasp immature females (copepodid stages II–V) for a period of up to a week prior to the female's terminal molt; upon maturation (stage VI) the female is inseminated and released. While females can mate anytime after their terminal molt, experiments using electrophoretically-detected genetic markers indicate that each mates only once in her lifetime. No evidence of sperm displacement was observed. Hence, male mating behavior can be interpreted as pre-copulatory mate guarding, a strategy employed to assure that a potential mate has not been previously inseminated. Males minimize the time investment required to insemiate a single female successfully by preferentially choosing to clasp more developmentally-advanced females; males clasped to stage III females will release them in order to clasp stage V females if the latter are present. Since males are capable of multiple mating, under most conditions of population sex ratio, this mating system results in low availability of unclasped, developmentally-advanced females; consequently, males must clasp successively younger (i.e. developmentally less-advanced) females in order to obtain a successful insemination.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00397511
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    Population structure of the intertidal copepod Tigriopus californicus as revealed by field manipulation of allele frequencies (1984)
    Springer
    Oecologia 65 (1984), S. 108-111 
    Details
    ISSN: 1432-1939
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Allele frequencies in natural T. californicus populations were perturbed by introduction of copepods from neighboring differentiated populations. In five experiments, the Gpt F allele was introduced into single recipient pools at a frequency of approximately 20%. In each case, the introduced allele declined to low frequencies (〈3%) in less than one month, apparently due to dilution by residents of other pools on the same outcrop. In a larger scale experiment, the Pgi F was introduced into four pools on a single small rock outcrop; all pools on the outcrop were subsequently monitored. While the allele frequency fell from approximately 40% to 10% during the first six weeks after the transplant, no further change in frequency was observed for the duration of the experiment (16 months). Within six weeks some spread of the allele to non-recipient pools on the same outcrop was observed; by eight months, allele frequencies in all pools on the outcrop were similar. Hence, despite the extensive turnover of subpopulations as single pools evaporate or are washed out, genetic homogeneity and stability of entire outcrops are maintained via extensive inter-pool gene flow; this contrasts sharply with the highly restricted levels of inter-outcrop gene flow.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00384471
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    Genetic differentiation of Texas Gulf Coast populations of the blue crab Callinectes sapidus (1993)
    Springer
    Marine biology 117 (1993), S. 227-233 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Allelic frequencies at three polymorphic, enzyme-encoding gene loci (GOT-2, EST-1, EST-2) were determined for Callinectes sapidus (Rathbun) megalopae and adults sampled along the Texas coast of the Gulf of Mexico. Significant temporal and spatial variation was observed at all three loci. Primary findings included: (1) megalopal allelic frequencies often differed significantly from those observed among neighboring adult populations; (2) larval allelic frequencies appeared to vary seasonally, with populations showing sharp differences in the summer months but tending to be more homogeneous in winter; (3) allelic frequencies among adult populations were significantly heterogeneous, but only one locus (EST-2) showed significant temporal variation; (4) juvenile and adult crabs sampled within one bay showed no size-specific differences in allelic frequencies. The spatial heterogeneity in allelic frequencies suggests that interpopulation gene flow is not sufficient to overcome population differentiation resulting from genetic drift and/or natural selection. Temporal variation in larval allelic frequencies suggests seasonal changes in larval source populations which may result from population differences in spawning season or developmental times or from seasonal changes in coastal current patterns.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00345667
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 7
    Electronic Resource
    Electronic Resource
    Genetic differentiation and reproductive incompatibility among Baja California populations of the copepod Tigriopus californicus (1995)
    Springer
    Marine biology 123 (1995), S. 821-827 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Populations of the harpacticoid copepod Tigriopus californicus were sampled from five sites from San Diego, California, to Playa Altamira, Baja California, Mexico. Allozyme analyses revealed that all the study populations are sharply differentiated genetically. At the extreme, two populations, Punta Baja and Playa Altamira, have no alleles in common at the seven allozyme loci studied. All pairwise interpopulation crosses successfully produced F2 hybrids except those involving the Playa Altamira population. All crosses using Playa Altamira females failed to produce F1 hybrids, while Playa Altamira males successfully produced F1 progeny with females from all other sites. These F1 offspring, however, were completely sterile (with San Diego and Punta Banda females) or only occasionally produced F2 offspring (with Punta Morro and Punta Baja females). These results suggest that allopatric differentiation among Baja populations has resulted in exceptionally high levels of genetic divergence and nearly complete reproductive isolation of the Playa Altamira population, which should now be recognized at the semispecies (or perhaps sibling species) level.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00349126
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 8
    Electronic Resource
    Electronic Resource
    Genetic heterogeneity among adult and recruit red sea urchins, Strongylocentrotus franciscanus (2000)
    Springer
    Marine biology 136 (2000), S. 773-784 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Allozyme electrophoresis was used to characterize genetic variation within and among natural populations of the red sea urchin Strongylocentrotus franciscanus. In 1995 to 1996, adult urchins were sampled from twelve geographically separated populations, seven from northern California and five from southern California (including Santa Rosa Island). Significant population heterogeneity in allelic frequencies was observed at five of six polymorphic loci. No geographic pattern of differentiation was evident; neighboring populations were often more genetically differentiated than distant populations. Northern and southern populations were not consistently distinguishable at any of the six loci. In order to assess within-population genetic variation and patterns of recruitment, large samples were collected from several northern California populations in 1996 and 1997, and were divided into three size classes, roughly representing large adults (〉60 mm), medium-sized individuals (31 to 60 mm, “subadults”) and individuals 〈2 yr of age (≤30 mm test diam, referred to as “recruits”). Comparisons of allelic counts revealed significant spatial and temporal differentiation among size-stratified population samples. Recruit samples differed significantly from adult samples collected at the same locale, and showed extensive between-year variation. Genetic differentiation among recruit samples was much higher in 1997 than in 1996. Between-year differences within populations were always greater for recruits than for adults. Potential explanations for the differentiation of recruit samples include pre- and post-settlement natural selection and high interfamily variance in reproductive success or “sweepstakes” recruitment. Unless recruit differentiation can be attributed to an improbable combination of strong and spatially diverse selection, such differentiation across northern California populations indicates that the larval pool is not well mixed geographically (even on spatial scales 〈20 km), despite long planktonic larval duration.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002270000281
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 9
    Electronic Resource
    Electronic Resource
    Allozyme and mitochondrial DNA evidence of population subdivision in the purple sea urchin Strongylocentrotus purpuratus (1996)
    Springer
    Marine biology 126 (1996), S. 443-450 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Despite high potential for dispersal, the purple sea urchin Strongylocentrotus purpuratus was found to have significant genetic subdivision among locations. Ten geographic locations along the coast of California and Baja California were sampled between 1994 and 1995. Samples from some locations included both adult and recruit urchins. Allozyme analyses revealed a genetic mosaic, where differentiation over short geographic distances could exceed differentiation over much larger distances. Significant allozyme differentiation was found among subpopulations of adults (standardized variance, F ST =0.033), among subpopulations of recruits (F ST =0.037), and between adults and recruits from the same location. DNA-sequence data for the mitochondrial cytochrome oxidase I gene also showed significant heterogeneity among locations, with a mild break in haplotype frequencies observed ≃ 300 km south of Point Conception. California. Repeated sampling over time is necessary to determine whether these patterns of differentiation are stable and to begin to understand what forces produce them.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00354626
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...