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physica status solidi (a) 02/2006; 64(1):K39 - K41. · 1.21 Impact Factor
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ABSTRACT: From capacitance measurements, the thermal capture cross-section of electrons at neutral gold centres is determined through the time dependence of the net ionized recombination centres concentration to σ = 1.24 × 10−16 (T/300)−(0.21 ± 0.03) cm2 in the temperature range 80 to 205 K.La section de capture thermique des électrons sur l'or neutre est déduite de la dépendance temporelle de la densité de centres profonds ionisés, mesurée par une technique capacitive. Pour le domaine de température 80 à 205 K le résultat est: σ = 1,24 × 10−16 (T/300)−(0,21 ± 0.03) cm2.
physica status solidi (a) 02/2006; 36(2):495 - 498. · 1.21 Impact Factor
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ABSTRACT: The energy levels and electrically active concentrations for platinum in n- and p-type Si, and for palladium in n-type silicon are measured by the dark transient capacitance technique, p+—n—p+ and n+—p—n+ structures have been platinum-diffused at low temperatures (820 to 844 °C). Two levels are found, a donor at Ev + 0.32 eV in p-type silicon and an acceptor at Ec — 0.24 eV in n-type silicon. These two levels are associated with the usual substitutional site (Pt(I)). The second usual site (Pt(II)) does not appear in samples, p+—n—p+ structures have been palladium-diffused at 898 °C. An acceptor level at Ec — 0.20 eV is found which is probably associated with the substitutional site of palladium in silicon.Nous avons déterminé, par la méthode des transitoires isothermes de capacité, les niveaux d'énergie et les densités d'atomes électriquement actifs pour le platine dans du silicium de type n et p et pour le palladium dans du silicium de type n. Des structures p+—n—p+ et n+—p—n+ ont été dopées au platine à basse température (820 à 844 °C). Nous trouvons deux niveaux, un donneur à Ev + 0.32 eV dans le type p et un accepteur à Ec — 0.24 eV dans le type n. Ces deux niveaux sont associés au site usuel substitutionnel (Pt(I)). Le second site couramment rencontré, (Pt(II)), n'est pas présent dans nos échantillons. Nous avons effectué des diffusions de palladium à 898 °C sur des structures p+—n—p+ et nous trouvons un niveau accepteur à Ec — 0,20 eV qui est probablement associé au site substitutionnel du palladium dans le silicium.
physica status solidi (a) 02/2006; 35(2):533 - 543. · 1.21 Impact Factor
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ABSTRACT: In a previous paper the authors proposed an interpretation of the fine structure of the no-phonon luminescence at 0.84 eV as arising from transitions at a substitutional Cr2+ ion on a Ga site subjected to a perturbation of C3v symmetry, and built a theoretical model. They now use this model in order to predict the Zeeman splittings; they observe good agreement with experiments.
Journal of Physics C Solid State Physics 11/2000; 14(13):1855.
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ABSTRACT: In a series of three papers (1981) the authors have recently proposed a coherent interpretation of different experimental results on the defect emitting a no-phonon luminescence at 0.84 eV in GaAs:Cr. According to the model, the transitions arise from a substitutional Cr2+ ion on a Ga site submitted to a perturbation having C3v symmetry but in which this trigonal effect is completely quenched in the ground set of states. This perturbation is induced by another defect present in the neighbourhood. In this paper they present a more precise study of the centre in its ground set of states. They extend the theory to try to interpret some phonon scattering experiments, but the complexity of the data prevents us from getting definitive conclusions on this point. The authors also present theoretical Zeeman splitting of the luminescence spectrum in the (110) direction, a result not given in their previous work.
Journal of Physics C Solid State Physics 11/2000; 14(36):5725.
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ABSTRACT: In a previous paper, (J. Physique Lett., vol.41, p.415, 1980), the authors proposed an interpretation of the fine structure of the no-phonon luminescence at 0.84 eV as arising from transitions at a substitutional Cr2+ ion on a Ga site subjected to a perturbation of C3v symmetry and advanced the main features of a theoretical model. In a second paper (ibid., vol.14, p.1855, 1981) they showed that this model leads to the proper description of the splittings in a magnetic field. Here they use this model to predict the splittings of the no-phonon luminescence lines under uniaxial stress, presenting experimental results and verifying that the model provides a correct interpretation of the observations. It is believed that this set of three papers offers a consistent view of the different experimental results on the defect. Few experimental facts-essentially the oscillator strengths for the electric-dipole transitions and the absence of shift of the low-energy lines for stress parallel to (110)-remains incompletely explained which is very satisfying with regard to the simplifying assumptions inherent in this type of calculation.
Journal of Physics C Solid State Physics 11/2000; 14(23):3447.
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Superlattices and Microstructures 01/1992; 12(1):7-15. · 1.49 Impact Factor
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ABSTRACT: We have unambiguously shown that low‐energy optical transitions generate electrons that belong either to the Γ minimum of GaAs or to the X minimum of AlAs, depending on the mean aluminum concentration, for a series of 5‐nm period GaAs/AlAs superlattices. We estimate the intensity of the potential responsible for the Γ‐X mixing to be on the order of 1–2 meV. For this kind of study, the photocurrent technique, which gives well‐structured spectra recorded on large spectral (≂0.7 eV) and temperature (4–300 K) ranges, appears more favorable than the photoluminescence excitation spectroscopy technique.
Journal of Applied Physics 06/1989; · 2.17 Impact Factor
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ABSTRACT: Point defects, introduced at 4.2 °K in p‐type silicon by 1.5‐MeV electron irradiation, are studied by means of the thermally stimulated capacitance technique. Electronic states associated with the vacancy and the divacancy are observed, which enables us to study their correlated annealing. The respective donor energy levels, hole thermal emission rates, and annihilation activation energies are measured.
Journal of Applied Physics 12/1976; · 2.17 Impact Factor
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ABSTRACT: A relaxation model for oscillations observed in deep-trap-doped pin structures under double-carrier injection is proposed. It appears that, when a critical voltage is reached, the cross-over zone (n0 = p0) of region i becomes unstable and initiates the propagation of damped waves toward the contacts, the decay time of which determines the frequency.Nous proposons un modéle de relaxation pour expliquer les oscillations observées dans les structures pin, dopées de centres recombinants profonds, en régime de double injection. Nous montrons que lorsque un potentiel critique est appliqué, la «zone de croisement» (définie par n0 = p0) de la région centrale devient instable et est la source d'ondes amorties qui se propagent vers les extrémités. Le temps d'amortissement de ces ondes détermine en général la fréquence des oscillations.
physica status solidi (a) 05/1971; 5(2):471 - 479. · 1.21 Impact Factor
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ABSTRACT: We have performed high resolution luminescence spectroscopy of a chromium related no-phonon multiplet. We deduce a new level scheme. This scheme and the oscillator strengths are conveniently interpreted as arising from transitions at substitutional Cr2+ ions on a Ga-site subjected to a perturbation of C3V symmetry. Nous avons effectué des expériences de spectroscopie à haute résolution sur la luminescence à 0,84 eV émise par GaAs : Cr. Nous obtenons un nouveau schéma des niveaux d'énergie. Ce schéma ainsi que les forces d'oscillateur sont bien interprétés en considérant l'émission par l'ion Cr2+ en site Ga soumis à une perturbation de symétrie C3V.
http://dx.doi.org/10.1051/jphyslet:019800041017041500.
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ABSTRACT: We adapt the thermally stimulated capacitance and dark transient capacitance technique to the study of silicon power devices. We use this method for the characterization of deep levels which appear at each stage of thyristor fabrication. We find three levels at Ec — (160 ± 5) meV, E c — (257 ± 4) meV and Ec — (542 ± 4) meV. The second and third levels are associated with quench induced recombination centers (Quenched-in centers). Nous appliquons la thermocapacitance et la méthode des transitoires de capacité dans l'obscurité aux dispositifs de puissance au silicium. Nous utilisons ces méthodes pour caractériser les niveaux d'énergie profonds induits à chaque étape de la fabrication de thyristors. Nous trouvons trois niveaux à Ec — (160 ± 5) meV, Ec — (257 ± 4) meV et Ec — (542 ± 4) meV. Le second et le troisième niveau sont associés à des centres recombinants induits par la trempe (Quenched-in centers).
http://dx.doi.org/10.1051/rphysap:01976001103040300.
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ABSTRACT: From capacitance measurements, the thermal capture cross-section of free holes at the platinium centre located at Ev + 0.34 eV is determined through the time dependence of the net ionized charges. In the temperature range [77 K, 120 K] the result is $$. La section efficace de capture thermique des trous sur le centre à Ev + 0,34 eV associé au platine dans le silicium est déduite de la dépendance temporelle de la densité des centres profonds ionisés, mesurée par technique capacitive. Pour le domaine de température [77 K, 120 K], le résultat est $$.
http://dx.doi.org/10.1051/rphysap:01980001504084300.
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ABSTRACT: We study two defects into natural semiconductor diamond. The first one emit a line positioned at 3.158 eV at 4 K : we assigne this luminescence to a transition between the excited and the ground state levels of the ND 1 centre. The second which emit in the range 3.8-4.581 eV and is characterized by a privileged coupling with one local phonon-mode, the energy of which is 236 meV, was named 5 RL by Wight [7]. We specify some features of its electronic structure and propose the identification to a carbon vacancy-acceptor complex. Nous étudions deux défauts dans le diamant naturel semiconducteur. La raie d'émission du premier, située à 3,158 eV à 4 K, est attribuable à une transition entre le niveau excité 4T1 et le niveau de base 4A2 du centre ND 1. Le second est positionné entre 3,8 et 4,581 eV et est caractérisé par un couplage privilégié avec un mode local de vibration d'énergie 236 meV : son spectre a été noté 5 RL par Wight [7]. Nous proposons l'identification à un complexe lacune de carbone-accepteur.
http://dx.doi.org/10.1051/rphysap:019800015010900.
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ABSTRACT: Using a time-resolved cathodoluminescence technique, we have investigated the radiative recombination in highly doped (Ga, Al)As epitaxial layers (the dopant was Si or Ge). We have realized in homogeneous Si-doped epitaxial (Ga, Al)As layers the conditions of large luminescence efficiency and great decay time usually observed in L.E.D. obtained by double liquid phase epitaxy of (Ga, Al)As on GaAs substrate. The phenomena are well explained if we consider the effect of charge impurity fluctuations in compensated semiconductors on the density of state tails at the edges of the band-gap. Au moyen d'une expérience de cathodoluminescence pulsée, nous avons étudié les recombinaisons radiatives dans des couches épitaxiées (Ga, Al) As fortement dopé ; le dopant est Si ou Ge. Dans des couches homogènes dopées au silicium nous avons obtenu les conditions de fort rendement lumineux et de longue durée de vie observées dans les diodes électroluminescentes réalisées par double épitaxie en phase liquide de (Ga, Al)As sur substrat GaAs. Les phénomènes sont bien expliqués en considérant l'effet des fluctuations des impuretés chargées dans les semiconducteurs fortement compensés sur les queues de densité d'états en bords de bande interdite.
http://dx.doi.org/10.1051/rphysap:01980001504086100.
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ABSTRACT: We study the electroluminescence of laser diodes GaAs/(Ga, Al)As. The I.R. band, located near 1 eV at room temperature, has three components at 77 K. One of them incomes from the active layer, another is emitted by the substrate. Nous étudions la bande d'électroluminescence des diodes laser à double hétérostructure GaAs/(Ga, Al)As située au voisinage de 1 eV à la température ambiante. Nous montrons que la bande d'électroluminescence comprend trois raies à 77 K : une est attribuée à la zone active et une au substrat.
http://dx.doi.org/10.1051/rphysap:01980001503071700.
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ABSTRACT: We report on photocurrent spectra of quasiperiodic superlattices which are greatly modified when an electric field is applied along the growth axis. We explain this behavior with a simple tight-binding model including only the superlattices sequences on which the different electronic states are peaked at zero electric field thus confirming the wavefunction “localization” of critical states.
Surface Science.
