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  • 1990-1994  (7)
  • 1994  (7)
Materialart
Erscheinungszeitraum
  • 1990-1994  (7)
Jahr
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  • 1
    Digitale Medien
    Digitale Medien
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 76 (1994), S. 4705-4712 
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: Carrier concentration and mobility of unintentionally doped InP layers, grown directly on Si using metal-organic vapor-phase epitaxy, have been studied. The formation of antiphase domains (APDs) was found to depend on annealing of the Si substrate in an AsH3 flow prior to epitaxial growth. Dislocation densities determined by the wet chemical delineation technique were (8±1)×107 cm−3, seemingly uncorrelated to APDs in the layers. In addition to a shallow donor and a compensating acceptor, a deep donor was observed affecting the temperature dependence of the free-electron concentration between 77 and 300 K. The electron mobility in this temperature range could be described in terms of the scattering mechanisms which are dominant in homoepitaxial InP, namely, scattering due to polar optical phonons, to ionized impurities, and to space charges. Electron scattering due to either of these mechanisms was strongly influenced by the occurrence of antiphase boundaries (APBs). The space-charge density as well as the degree of compensation of the epitaxial layers increases with the density of APBs. Degraded 300 K mobilities were obtained indicating the effect of local stress at the APB.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 101 (1994), S. 10481-10484 
    ISSN: 1089-7690
    Quelle: AIP Digital Archive
    Thema: Physik , Chemie und Pharmazie
    Notizen: We calculate the modifications of the unimolecular rate constants for free metallic clusters due to thermally exited electronic degrees of freedom. The effect is essentially taken into account by substituting Helmholtz's free energy of the electronic system for the ground state energy. The activation energy pertaining to the electronic ground states of the mother and daughter cluster is then replaced by the first difference in Helmholtz's free energy. © 1994 American Institute of Physics.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 3
    Digitale Medien
    Digitale Medien
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 2615-2622 
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: A computer controlled acquisition and evaluation system for electrostatic probes is presented. Fully automatic evaluation of the probe characteristics yields electron temperature, plasma potential, and density during the recording. Two-dimensional probe positioning is accomplished with stepping motors. The system is characterized by 12-bit probe current resolution and extremely wide probe voltage range (±130 V). It is tested in a collisionless argon magnetoplasma and compared to standard wave diagnostic techniques for magnetized plasmas, i.e., the resonance cone technique. The influence of the probe radius on the electron current in a magnetized plasma is studied experimentally. The two techniques yield identical density and temperature values within 20% accuracy and therefore show the reliable applicability of the automatic evaluation system.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 4
    ISSN: 1359-5997
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Architektur, Bauingenieurwesen, Vermessung
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 5
    Digitale Medien
    Digitale Medien
    Springer
    International journal of colorectal disease 9 (1994), S. 177-179 
    ISSN: 1432-1262
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Beschreibung / Inhaltsverzeichnis: Résumé Les patients danois porteurs d'un syndrome de Peutz-Jeghers sont enregistrés dans le registre danois des polyposes. Nous avons débuté un nouveau programme de follow-up en nous basant sur les données récentes de la littérature et sur nos propres cas. Le suivi a été ajusté sur la vitesse de croissance des polypes alors que chez les patients asymptomatiques et qui présentaient un taux de croissance lent, les contrôles ont pu être espacés. Le programme comporte des endoscopies hautes et basses du tractus gastro-intestinal, un transit baryté suivi et, dans certains cas, chez des porteurs de polypes étendus ou asymptomatiques, une laparotomie a été réalisée avec une entéroscopie pertopératoire totale complétée par des polypectomies. Un examen de la cavité pelvienne, un frottis cervical, une palpation du sein et des testicules ont été réalisés chez toux les patients âgés de plus de 30 ans.
    Notizen: Abstract Danish patients with Peutz-Jeghers syndrome are registered in the Danish Polyposis Register. We have initiated a new follow-up programme based on recent literature including our own cases. This has been adjusted to the regrowth rate of the polyps whereby patients with no symptoms and low regrowth rate are followed with few examinations. The programme includes upper and lower gastrointestinal endoscopy, small bowel enema and in cases with large or symptomatic polyps, laparotomy with intraoperative total enteroscopy with polypectomy as required. Pelvic examination, cervical smear, breast and testicular examination are carried out after the age of 30 years.
    Materialart: Digitale Medien
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  • 6
    ISSN: 1434-6036
    Schlagwort(e): 71.25.T ; 71.25.J
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract Shubnikov-de Haas investigations onn-InP are presented and the effective mass as a function of carrier concentration is determined. The experiments are carried out with bulk and liquid phase epitactically grown material and carrier concentrations betweenn=1017 and 1019cm−3. Temperatures employed ranged fromT=2 to 77 K and magnetic fields were applied up toB=22 T. Supplementing Kane's theory by introducing both temperature and electron concentration dependence, the nonparabolicity of the effective mass for temperatures betweenT=0 K and 300 K is calculated. The result fits quite well to the experimental results.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 7
    ISSN: 1434-6052
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract K+K+ and K−K− correlations from S+Pb collisions at 200 GeV/c per nucleon and K+K+ correlations from p+Pb collisions at 450 GeV/c per nucleon, are presented as measured by the focusing spectrometer of the NA44 experiment at CERN. Multidimensional fits are performed in order to characterize the kaon-emission volume, which is found to be smaller than the pion-emission volume.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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