Generation‐recombination noise analysis in heavily doped p‐type GaAs transmission line models

Low-frequency noise measurements are performed on heavily doped p-type GaAs transmission line models. Excess noise exhibits 1/f noise and generation-recombination (GR) noise components. A study of the GR components vs device geometry shows the spectral densities due to contact resistances to be negligible. Thus the noise sources due to the volume resistances are predominant, and have to be located in the bulk layer or in the space-charge region of the devices. These two possibilities concerning the location of the GR noise sources are investigated. For both cases, expressions for the variance and the relaxation time associated to fluctuations in the charge carriers are given. The comparison between the experimental data with the theoretical results shows that the GR noise sources are located in all probability in the space-charge region

Shot noise in mesoscopic systems

This is a review of shot noise, the time-dependent fluctuations in the electrical current due to the discreteness of the electron charge, in small conductors. The shot-noise power can be smaller than that of a Poisson process as a result of correlations in the electron transmission imposed by the Pauli principle. This suppression takes on simple universal values in a symmetric double-barrier junction (suppression factor 1/2), a disordered metal (factor 1/3), and a chaotic cavity (factor 1/4). Loss of phase coherence has no effect on this shot-noise suppression, while thermalization of the electrons due to electron-electron scattering increases the shot noise slightly. Sub-Poissonian shot noise has been observed experimentally. So far unobserved phenomena involve the interplay of shot noise with the Aharonov-Bohm effect, Andreev reflection, and the fractional quantum Hall effect.Comment: 37 pages, Latex, 10 figures (eps). To be published in "Mesoscopic Electron Transport," edited by L. P. Kouwenhoven, G. Schoen, and L. L. Sohn, NATO ASI Series E (Kluwer Academic Publishing, Dordrecht

Generation‐recombination noise in submicron semiconductor layers: Influence of the edge

In highly doped thin semiconductor layers one often observes generation-recombination (g-r) noise with a broadened Lorentzian-like spectrum. In a theoretical analysis we have shown that such a spectrum can be ascribed to g-r processes between conduction band and monoenergetic traps in the edge of the layers

HOT CARRIERS IN REDUCED GEOMETRY SURFACE-CHANNEL CHARGE-COUPLED DEVICES

In a surface-channel C.C.D., electric fields have been computed with the help of a finite-difference method. The normal field, higher than the critical value, can create impact ionization under the gates but not in the gaps. Nevertheless this field is not crucial for the C.C.D. operation as a shift register. The longitudinal field, defined as the sum of two components, is higher than the critical field but at the very beginning of the transfer. All those results have been found again for a theoretical device with 1.5 µm gate length. Nevertheless this heating of the carriers is found to be the major limitation to the maximum transfer frequency

Generation‐recombination noise in submicron semiconductor layers: Influence of the edge

In highly doped thin semiconductor layers one often observes generation-recombination (g-r) noise with a broadened Lorentzian-like spectrum. In a theoretical analysis we have shown that such a spectrum can be ascribed to g-r processes between conduction band and monoenergetic traps in the edge of the layers

HOT CARRIERS IN REDUCED GEOMETRY SURFACE-CHANNEL CHARGE-COUPLED DEVICES

Pour un C.C.D. à canal en surface, les champs électriques à l'interface ont été calculés par une méthode numérique (différences finies). Le champ normal supérieur au champ critique peut donner lieu à de l'ionisation par impact sous le milieu des grilles mais pas dans les espaces interelectrodes. Néanmoins, le rôle de ce champ a peu de conséquences sur le fonctionnement en registre à décalage de ces dispositifs. Le champ longitudinal, défini comme la somme de deux composantes n'est supérieur au champ critique que pour une très faible partie du stade initial du transfert. Tous ces résultats ont été retrouvés sur une structure théorique ayant une longueur de grille de 1.5 µm. Néanmoins, cet effet de chauffage des porteurs est la cause principale de la limitation de la fréquence maximum des transferts.In a surface-channel C.C.D., electric fields have been computed with the help of a finite-difference method. The normal field, higher than the critical value, can create impact ionization under the gates but not in the gaps. Nevertheless this field is not crucial for the C.C.D. operation as a shift register. The longitudinal field, defined as the sum of two components, is higher than the critical field but at the very beginning of the transfer. All those results have been found again for a theoretical device with 1.5 µm gate length. Nevertheless this heating of the carriers is found to be the major limitation to the maximum transfer frequency

Utilisation des mesures de bruit pour la détermination du photocourant primaire dans les photodiodes à avalanche N+Pπ P+ au silicium

The use of a photodetector requires a satisfactory knowledge about the noise equivalent power which is a function of the multiplication of the charge carriers. In a silicon diode of the type N+PπP+, the extension of the space charge and the impact ionisation together cause an increase in the initial photocurrent. It is the purpose of this paper to make a distinction between these two effects. The former increases the primary photocurrent whereas the latter multiplies it. Noise measurements are used to mark this transition. The authors show in particular that the increase of the primary photocurrent due to the extended space charge region can attain a factor of two (if this value is unknown, the errors in the determination of the noise equivalent power of the photodiode can be substantial).L'utilisation d'un photodétecteur nécessite la connaissance de sa puissance équivalente de bruit qui est une fonction du facteur de multiplication des porteurs de charges. Dans une photodiode au Si du type N+PπP +, l'extension de la zone de charge d'espace et l'ionisation par impact des porteurs entraînent simultanément une augmentation du photocourant initial. L'objet de cet article est de dissocier les deux effets, le premier ayant pour conséquence l'augmentation du photocourant primaire qui sera alors multiplié pour donner le courant résultant. Les mesures de bruit de fond permettent d'atteindre le photocourant non multiplié. Les auteurs montrent dans le cas particulier de ces dispositifs que l'augmentation du photocourant primaire due à l'extension de la charge d'espace peut atteindre un facteur 2. (La non-connaissance de cette valeur entraînant naturellement d'importantes erreurs sur la détermination de la puissance équivalente de bruit de la photodiode en régime de fonctionnement)