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  • 1
    Electronic Resource
    Electronic Resource
    Effective sulfur passivation of an n-type GaN surface by an alcohol-based sulfide solution (2000)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 87 (2000), S. 4591-4593 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The sulfur passivation of an n-GaN surface was investigated by employing an aqueous (NH4)2S solution and (NH4)2S+t-C4H9OH solution. Photoluminescence and Auger electron spectroscopy revealed that treatment with (NH4)2S+t-C4H9OH results in a more effective passivation of the n-GaN surface than that with (NH4)2S due to a higher chemical reactivity of sulfur species in the former solution. The (NH4)2S+t-C4H9OH-treated sample shows a stronger photoluminescence intensity by a factor of 2.5 with respect to an untreated sample. In addition, improved Ohmic characteristics of the sample are evident from current–voltage measurements. This result can be attributed to the effective removal of an insulating layer on the n-GaN surface. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.373107
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  • 2
    Electronic Resource
    Electronic Resource
    InGaN/GaN multiple quantum well light-emitting diodes with highly transparent Pt thin film contact on p-GaN (2000)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 87 (2000), S. 4464-4466 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The fabrication and characterization of an InGaN/GaN multiple quantum well light-emitting diode (LED) with a highly transparent Pt thin film as a current spreading layer are described. The room temperature electroluminescence exhibits a strong emission at 453 nm. Pt-contacted LEDs show good electrical properties and high light-output efficiency compared to Ni/Au-contacted ones. The light transmittance and the specific contact resistance of a Pt thin film with a thickness of 8 nm on p-GaN was determined to be 85% at 450 nm and 9.12×10−3 Ω cm2, demonstrating that a Pt thin film can be used as an effective current spreading layer with high light transparency. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.373092
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  • 3
    Electronic Resource
    Electronic Resource
    Dry etch damage in n-type GaN and its recovery by treatment with an N2 plasma (2000)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 87 (2000), S. 7667-7670 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report on etch-induced damage in n-type GaN caused by an inductively coupled plasma, and damage recovery by means of treatment with an N2 plasma. As the plasma dc bias was increased by increasing the rf table power during etching, the optical and electrical properties of the etched GaN films deteriorated as the result of etch-induced damage. However, an N2 plasma treatment for the etched samples effectively removed the etch-induced defects and damage on the surface, leading to improved surface morphology, photoluminescence, and ohmic contact in n-type GaN. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.373438
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  • 4
    Electronic Resource
    Electronic Resource
    Effects of sulfur treatment on electrical and optical performance of InGaN/GaN multiple-quantum-well blue light-emitting diodes (2001)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 78 (2001), S. 1766-1768 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The results of the sulfur treatment of multiple-quantum-well (MQW) light-emitting diodes (LEDs) with (NH4)2S and (NH4)2S+t-C4H9OH solutions prior to the deposition of a light-transmitting p-electrode metal are presented. The room-temperature I–V curves showed that the forward voltages of MQW LEDs treated with the two sulfur solutions decrease by 0.12 and 0.35 V at 20 mA, respectively, compared to the untreated MQW LED, as the result of an improvement in p-Ohmic contact characteristics. The relative light-output power and external quantum efficiency of MQW LEDs increased by a factor of 1.28 for the (NH4)2S treated sample and 2.23 for the (NH4)2S+t-C4H9OH treated sample compared to the untreated sample. In addition, the reverse leakage current characteristic of MQW LEDs was reduced as a result of sulfur treatment. This can be attributed to the passivation of surface and sidewall damages formed after the dry-etching process for a reliable pattern transfer. The present results indicate that the sulfur treatment greatly improves the electrical and optical performance of MQW LEDs. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1355990
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  • 5
    Electronic Resource
    Electronic Resource
    Effect of alcohol-based sulfur treatment on Pt Ohmic contacts to p-type GaN (2001)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 78 (2001), S. 1942-1944 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The effects of an alcohol-based (NH4)2S solution [t-C4H9OH+(NH4)2S] treatment on Pt Ohmic contacts to p-type GaN are presented. The specific contact resistance decreased by three orders of magnitude from 2.56×10−2 to 4.71×10−5 Ω cm2 as a result of surface treatment using an alcohol-based (NH4)2S solution compared to that of the untreated sample. The O 1s and Pt 4f core-level peaks in the x-ray photoemission spectra showed that the alcohol-based (NH4)2S treatment was effective in removing of the surface oxide layer. Compared to the untreated sample, the alcohol-based (NH4)2S-treated sample showed a Ga 2p core-level peak which was shifted toward the valence-band edge by 0.25 eV, indicating that the surface Fermi level was shifted toward the valence-band edge. These results suggest that the surface barrier height for hole injection from Pt metal to p-type GaN can be lowered by the surface treatment, thus resulting in a drastic reduction in specific contact resistance. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1358356
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  • 6
    Electronic Resource
    Electronic Resource
    Reactivation of Mg acceptor in Mg-doped GaN by nitrogen plasma treatment (2000)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 76 (2000), S. 3079-3081 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Mg-doped GaN films, grown by metalorganic chemical vapor deposition, were treated with a nitrogen plasma after a conventional rapid thermal annealing (RTA). The conductivity of the p-type GaN film was greatly enhanced by nitrogen plasma treatment, and exhibited a higher sheet hole concentration as well as lower sheet resistance than the RTA samples. A photoluminescence (PL) band which peaked at 3.27 eV was new, and a band at 2.95 eV was markedly attenuated in the plasma treated samples. PL measurements suggest that self-compensation in a Mg-doped GaN caused by the nitrogen vacancies is effectively reduced by the nitrogen plasma treatment, leading to an enhanced p-type conductivity. In addition, the plasma-treated sample revealed a drastic reduction in specific contact resistance by three orders of magnitude, compared with the RTA samples. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.126585
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  • 7
    Electronic Resource
    Electronic Resource
    Modeling of a GaN-based light-emitting diode for uniform current spreading (2000)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 77 (2000), S. 1903-1904 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The characteristics of the GaN/InGaN multiquantum-well light-emitting diode (LED) have been examined from the view point of uniform current spreading. By means of simple modeling, it was found that the current density and the length of the lateral current path through the transparent layer represent dominant parameters in determining uniform current spreading. In this regard, we studied the effect of current density on the reliability characteristics of the LED. We were able to significantly improve the electrical, optical, and reliability characteristics of the LED in terms of reducing the length of the lateral current path through the transparent layer. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1311819
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  • 8
    Electronic Resource
    Electronic Resource
    Protective Effect of Microencapsulation Consisting of Multiple Emulsification and Heat Gelation Processes on Immunoglobulin in Yolk (2005)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of food science 70 (2005), S. 0 
    Details
    ISSN: 1750-3841
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Process Engineering, Biotechnology, Nutrition Technology
    Notes: : Two different emulsification methods involving multiple emulsification and heat gelation were used for preparation of whey protein-based microcapsules containing immunoglobulin in yolk (IgY). The residual activity of IgY during the emulsion preparation and the effects of microencapsulation on IgY stability under harsh conditions were investigated. The residual activity of IgY in an emulsion prepared with a membrane emulsifier was higher than for an emulsion using a homogenizer. Microencapsulated IgY showed remarkable stability against both pepsin and acid. Both microencapsulated IgY and nonencapsulated IgY were relatively stable in bile and artificial intestinal juice. Microencapsulated IgY retained 74% of initial activity during heat treatment. There were no significant differences in the residual activities of microencapsulated IgY under storage temperatures of 4, 25, and 37°C.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2621.2005.tb07088.x
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  • 9
    Electronic Resource
    Electronic Resource
    Nucleophilic substitution reaction of benzyl bromide with N, N-Dimethylaniline: Significance of equilibrium cross-interaction constant (1994)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 7 (1994), S. 555-560 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Kinetic studies on the reversible reactions of benzyl bromides with N, N-dimethylanilines were carried out for both the forward (kf) and reverse (kr) directions. The equilibrium constants, K were calculated using the ratio kf/kr and the equilibrium cross-interaction constant, ρeXY was determined. The ρeXY value was shown to represent a maximum intensity of interactions between substituents X and Y through covalent bonds within a molecule. The normalized values of ρX (ρnuc) and ρXY indicate that in the transition state the fractional development or loss of polar and resonance interactions in the benzyl system are imbalanced or non-perfectly synchronized. In the forward reaction the fractional loss of resonance interaction becomes enhanced, whereas in the reverse reaction the fractional development of resonance interaction lags behind the corresponding changes of polar interactions by ca 45%.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610071006
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  • 10
    Electronic Resource
    Electronic Resource
    Cross-interaction constants as a measure of the transition state structure. Part 9. The degree of bond formation in the SN2 transition state involving anionic nucleophiles (1990)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 3 (1990), S. 550-554 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The second-order rate constants of the reactions between benzenesulphonyl chlorides and anionic nucleophiles, benzoates and cinnamates, in methanol at 30·0°C are reported. A marked increase in rate found with a p-nitro substituent in the substrate indicated the development of an electron-rich centre on the S atom in the transition state. The two types of cross-interaction constants, ρxy and λxy, suggested that bond formation in the SN2 transition state with anionic nucleophiles is greater than that for the corresponding reaction with aniline nucleophiles.
    Additional Material: 5 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610030809
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