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Application of intermixing to p-type GaAs/AlAs distributed Bragg reflectors for series resistance reduction in vertical cavity devices (1995)

Khan, A. ; Woodbridge, K. ; Ghisoni, M. ; [weitere]

[S.l.] : American Institute of Physics (AIP)

Journal of Applied Physics 77 (1995), S. 4921-4926

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ISSN: 1089-7550

Quelle: AIP Digital Archive

Thema: Physik

Notizen: In this paper we experimentally investigate the application of selective interdiffusion to p-type (Zn doped) distributed Bragg reflectors, as employed within a range of vertical cavity devices, as a means of lowering the series resistance. Various rapid thermal anneal temperatures and times are studied, both with and without silica encapsulants. The degree of intermixing, and hence series resistance reduction, is found to be cap dependent and this is verified both by secondary ion mass spectrometry and electrical resistance measurements. Both these techniques suggest that the intermixing, due primarily to Zn enhanced interdiffusion, is increased when no encapsulant is used. In this case a series resistance reduction approaching 50% is achieved within the 14 period GaAs/AlAs Bragg reflector. In the silica encapsulated case Ga vacancies are injected into the structure and these suppress the movement of Zn. The resulting Ga diffusion coefficient in this case is found to decrease by a factor of 3 relative to the uncapped case. The effects of interdiffusion on the reflection properties of the reflector, under various anneal conditions, are also described. This has previously been studied theoretically [Floyd et al., J. Appl. Phys. 75, 7666 (1994)] but here we offer experimental evidence on the optical effects of intermixing. We show that the peak reflectivity is found to decrease only slightly with temperature and time, again depending on capping conditions. The major effect contributing to the reflectivity decrease however is surface degradation due to As out-diffusion. The reflectivity does decrease appreciably (∼10%) when the interdiffusion length of the group III atoms becomes a significant fraction of the quarter-wave thickness of the GaAs/AlAs layers, as demonstrated in samples annealed at high temperatures and for long times (960 °C/360 s). These issues, along with that of planar integration of vertical cavity lasers and other devices such as modulators and detectors, are of importance for future applications. © 1995 American Institute of Physics.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1063/1.359297

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Two-step room temperature grain growth in electroplated copper (1999)

Brongersma, S. H. ; Richard, E. ; Vervoort, I. ; [weitere]

[S.l.] : American Institute of Physics (AIP)

Journal of Applied Physics 86 (1999), S. 3642-3645

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ISSN: 1089-7550

Quelle: AIP Digital Archive

Thema: Physik

Notizen: Electroplated copper exhibits some surprising changes at room temperature in sheet resistance, stress, and microstructure. This behavior, now known as self-annealing, is shown here to be intimately linked to the composition of the plating bath and the resulting incorporation of organic additives in the Cu layer. Their addition is a necessary condition for self-annealing to occur, but slows down the process for higher concentrations. The phenomenon also depends critically on film thickness, showing an accelerated transformation when film thickness increases. This dependence is explained in terms of a very rapid primary crystallization from the top surface down just after deposition, followed by a slower lateral recrystallization producing large secondary grains. The stress and sheet resistance during recrystallization are identified as two noncorrelated variables. © 1999 American Institute of Physics.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1063/1.371272

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Thermally induced solid state polycondensation of nylon 66, nylon 6-10 and polyethylene terephthalate (1969)

Chen, F. C. ; Griskey, Richard G. ; Beyer, G. H.

Hoboken, NJ : Wiley-Blackwell

AIChE Journal 15 (1969), S. 680-685

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ISSN: 0001-1541

Schlagwort(e): Chemistry ; Chemical Engineering

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung

Notizen: The mechanism of solid state polycondensation has been subjected to a fundamental analysis. Equations were formulated for combined diffusion and chemical reaction for two separate situations. One was for solid state polycondensation in polymer flakes or chips. The other dealt with polymer powders. The resultant solutions related molecular weight changes to rate functions. A technique for deriving the rate functions from experimental data is described.Solid state polycondensations were then studied for nylon 66, nylon 6-10, and polyethylene terephthalate. These data which ranged from 120 to 200°C. were tested with various mechanisms. The most appropriate one was found to be that developed in the present work. Chemical reaction was found to be the rate controlling step in solid state polycondensation in nylon 66, polyethylene terephthalate, powders of nylon 6-10 and larger particles of nylon 6-10 at and above 160°C. Diffusion of byproduct through the solid was the rate controlling step for larger particles of nylon 6-10 at temperatures below 160°C. Thermograms of nylon 6-10 indicated morphological changes which possibly influenced the behavior of the larger nylon 6-10 particles. The Arrhenius relation was fitted to the situations where chemical reaction controlled.

Zusätzliches Material: 11 Ill.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1002/aic.690150510

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Radiochemische Messung der Löslichkeit von Bleisulfat (1965)

Lieser, K. H. ; Beyer, G. ; Lakatos, E.

Weinheim : Wiley-Blackwell

Zeitschrift für anorganische Chemie 339 (1965), S. 208-213

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ISSN: 0044-2313

Schlagwort(e): Chemistry ; Inorganic Chemistry

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Chemie und Pharmazie

Beschreibung / Inhaltsverzeichnis: Using 210Pb as an indicator, the solubility and conductivity of PbSO4 in water and aqueous solutions of Na2SO4 at various concentrations have been measured as functions of the time, partially in 0.5 M NaClO4 medium. PbSO4 shows a strong time dependence of its solubility being due to the slow formation of neutral complexes in the solution. The formation of a disulfato-complex [Pb(SO4)2]2-, however, is not indicated, even in 1 M Na2SO4.

Notizen: Unter Verwendung von Pb-210 wurde die Löslichkeit von Bleisulfat in Wasser und in Natriumsulfatlösungen verschiedener Konzentration als Funktion der Zeit gemessen. Eine Versuchsreihe wurde ohne Zusatz eines weiteren Elektrolyten ausgeführt, eine weitere Versuchsreihe in 0,5 m NaClO4-Lösung. Auch die Leitfähigkeit wurde als Funktion der Zeit verfolgt. Als Besonderheit des Bleisulfats wurde eine stark ausgeprägte Zeitabhängigkeit der Löslichkeit gefunden, die auf die langsame Bildung neutraler Komplexe in der Lösung zurückzuführen ist. Die Bildung eines Disulfatokomplexes [Pb(SO4)2]2- ist jedoch auch in 1 m Na2SO4-Lösung noch nicht erkennbar.

Zusätzliches Material: 4 Ill.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1002/zaac.19653390310

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