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Serge Luryi - One of the best experts on this subject based on the ideXlab platform.

  • edge excitation geometry for studying intrinsic emission spectra of bulk n inp
    Journal of Luminescence, 2014
    Co-Authors: Oleg G Semyonov, Arsen Subashiev, Zhichao Chen, Serge Luryi
    Abstract:

    The shape of the photoluminescence line excited at an edge face of InP wafer and registered from the broadside is used to investigate the intrinsic emission spectrum. The procedure is much less sensitive to the surface properties and the carrier kinetics than the conventional methods used with the reflection or transmission geometry of photoluminescence. Our method provides a tool for studying the effects of non-equilibrium distribution of Minority Carriers in doped direct-band semiconductors.

  • temperature controlled levy flights of Minority Carriers in photoexcited bulk n inp
    Physics Letters A, 2014
    Co-Authors: Arsen Subashiev, Oleg G Semyonov, Zhichao Chen, Serge Luryi
    Abstract:

    Article history: We study by photoluminescence the spatial distribution of Minority Carriers (holes) arising from their anomalous photon-assisted diffusion upon photo-excitation at an edge of n-InP slab for temperatures ranging from 300 K to 78 K. Giant enhancement in the spread of holes — over distances exceeding 1 cm from the excitation edge — is seen at lower temperatures. We show that the experiment provides a realization of the "Levy flight" random walk of holes, in which the Levy distribution index γ is controlled by the temperature. The variation γ (T ) is close to that predicted earlier, γ = 1−Δ/kT ,w hereΔ(T ) is the Urbach tailing parameter of the absorption spectra. This theoretical prediction is based on the assumption of a quasi-equilibrium intrinsic emission spectrum in the form due to van Roosbroeck and Shockley. © 2013 Elsevier B.V. All rights reserved.

  • levy flight of photoexcited Minority Carriers in moderately doped semiconductors theory and observation
    Future Trends in Microelectronics: Frontiers and Innovations, 2013
    Co-Authors: Arsen Subashiev, Serge Luryi
    Abstract:

    This chapter contains sections titled: Introduction Anomalous Diffusion of the Minority Carriers Single Step Probability Distribution Distribution Along a Band: Boundary Effects Experimental Luminescence Spectra and Observation of the L��vy Flight Distribution of the Minority Carriers A Single Big Jump Approximation for the Truncated L��vy Flight Conclusions ]]>

  • levy flight of photoexcited Minority Carriers in moderately doped semiconductors theory and observation
    arXiv: Materials Science, 2012
    Co-Authors: Arsen Subashiev, Serge Luryi
    Abstract:

    Spatial spread of Minority Carriers produced by optical excitation in semiconductors is usually well described by a diffusion equation. The classical diffusion process can be viewed as a result of a random walk of particles in which every step has the same probability distribution with a finite second moment. This allows applying the central limit theorem to the calculation of the particle distribution after many steps. However, in moderately doped direct-gap semiconductors the photon recycling process can radically modify the spatial spread. For this process, the steps in the random walk are defined by the reabsorption length of photons produced in radiative recombination. The step distribution has an asymptotic power-law decline. Moments of this distribution diverge and the displacement is governed by rare but large steps. Random walk of this kind is called the Levy flight. It corresponds to an anomalously large spread in space and a modified ("super-diffusive") temporal evolution. Here we discuss the first direct observation of the hole profile in n-doped InP samples over distances of the order of a centimeter and more than two orders of magnitude in hole concentration. Luminescence spectra and intensity were studied as a function of distance from the photo-excitation in a rather unusual geometry (homogeneous excitation of the wafer edge and observation of the luminescence spectra from the broadside). The intensity is proportional to the Minority-carrier concentration and exhibits a slow power-law drop-off with no changes in the spectral shape. This power law gives a direct evidence of Levy-flight transport. It has enabled us to evaluate the index of the distribution, the characteristic distance of the Minority-carrier spread and the photon recycling factor. The results are in good agreement with the theoretical analysis.

  • photon assisted levy flights of Minority Carriers in n inp
    Journal of Luminescence, 2012
    Co-Authors: Oleg G Semyonov, Arsen Subashiev, Zhichao Chen, Serge Luryi
    Abstract:

    Abstract We study the photoluminescence spectra of n-doped InP bulk wafers, both in the reflection and the transmission geometries relative to the excitation beam. From the observed spectra we estimate the spatial distribution of Minority Carriers allowing for the spectral filtering due to reabsorption of luminescence in the wafer. This distribution unambiguously demonstrates a non-exponential drop-off with distance from the excitation region. Such a behavior evidences an anomalous photon-assisted transport of Minority Carriers enhanced owing to the high quantum efficiency of emission. It is shown that the transport conforms very well to the so-called Levy-flights process corresponding to a peculiar random walk that does not reduce to diffusion. The index γ of the Levy flights distribution is found to be in the range γ = 0.64 –0.79, depending on the doping. Thus, we propose the high-efficiency direct-gap semiconductors as a remarkable laboratory system for studying the anomalous transport.

Jeanmichel Sallese - One of the best experts on this subject based on the ideXlab platform.

  • methodology for 3 d substrate network extraction for spice simulation of parasitic currents in smart power ics
    IEEE Transactions on Computer-Aided Design of Integrated Circuits and Systems, 2016
    Co-Authors: Pietro Buccella, Yasser Moursy, Ramy Iskander, Hao Zou, Camillo Stefanucci, Jeanmichel Sallese, Maher Kayal
    Abstract:

    A 3-D simulation of substrate currents is crucial to analyze parasitic coupling effects due to Minority carrier injection in smart power ICs. In this paper, a substrate parasitic extraction methodology is introduced by dividing the IC layout into elementary elements to solve the continuity equation for Minority Carriers in the volume based on the finite-difference method. A substrate parasitic network is derived from the mesh generated through the existing mixed-signal design flow. The induced substrate model is included in circuit simulators such as SPICE to predict the effects of substrate couplings during the design phase. Furthermore, this analysis enables optimization of layout with minimal parasitic effects. By linking the substrate model to the active components, the couplings between the integrated circuit with the substrate parasitic currents can be analyzed during circuit simulations. Simulations and measurements on an high voltage driver reveal consistent results and therefore confirm the validity of the method. Therefore, the approach developed herein is effective to predict parasitic couplings due the injection of Minority Carriers.

  • spice compatible modeling of high injection and propagation of Minority Carriers in the substrate of smart power ics
    Solid-state Electronics, 2015
    Co-Authors: Camillo Stefanucci, Pietro Buccella, Maher Kayal, Jeanmichel Sallese
    Abstract:

    Abstract Classical substrate noise analysis considers the silicon resistivity of an integrated circuit only as doping dependent besides neglecting diffusion currents as well. In power circuits Minority Carriers are injected into the substrate and propagate by drift–diffusion. In this case the conductivity of the substrate is spatially modulated and this effect is particularly important in high injection regime. In this work a description of the coupling between majority and Minority drift–diffusion currents is presented. A distributed model of the substrate is then proposed to take into account the conductivity modulation and its feedback on diffusion processes. The model is expressed in terms of equivalent circuits in order to be fully compatible with circuit simulators. The simulation results are then discussed for diodes and bipolar transistors and compared to the ones obtained from physical device simulations and measurements.

  • modeling Minority Carriers related capacitive effects for transient substrate currents in smart power ics
    IEEE Transactions on Electron Devices, 2015
    Co-Authors: Camillo Stefanucci, Pietro Buccella, Maher Kayal, Jeanmichel Sallese
    Abstract:

    This paper presents an extended model for transient and ac circuit-level simulation of Minority Carriers propagation through the substrate of smart power integrated circuits (ICs). A p-n junction and a diffusion resistor with capacitive components are proposed to efficiently simulate transient parasitic coupled currents in high-power stages. From a general chip layout, an equivalent substrate network including capacitive effects (junction and diffusion capacitances) can be extracted and parasitic bipolar transistor can be simulated for the first time in transient operation by circuit simulators once the Minority Carriers continuity conditions are satisfied. This paper shows simulation results of the implemented models in good agreement with those obtained from technology computer-aided design. This implies that transient layout dependent mechanisms between high-voltage aggressor wells and low-voltage victims can be verified in early stages of IC design flow.

  • impact of enhanced contact doping on Minority Carriers diffusion currents
    Conference on Ph.D. Research in Microelectronics and Electronics, 2014
    Co-Authors: Camillo Stefanucci, Pietro Buccella, Maher Kayal, Jeanmichel Sallese
    Abstract:

    Minority Carriers diffusion currents are particularly important in parasitic substrate couplings of Smart Power ICs. In CMOS technologies the P-substrate potential is imposed by P+ contacts and N-wells by N+ highly doped implantations. The doping concentration discontinuity of these contact regions can have a big impact on parasitic diffusion currents of Minority Carriers. This work gives a description of these effects by device physical simulations of PN junctions under different injection levels of Minority Carriers. The perturbation of boundary conditions for electrons diffusion is also studied inside the substrate bulk in case a highly-doped substrate is used for high-voltage technologies.

  • spice simulation of substrate Minority Carriers propagation with equivalent electrical circuit
    International Conference Mixed Design of Integrated Circuits and Systems, 2014
    Co-Authors: Pietro Buccella, Camillo Stefanucci, Jeanmichel Sallese, Maher Kayal
    Abstract:

    This paper presents an equivalent electrical circuit for one dimensional substrate Minority Carriers spice simulation. The electrical circuit parameters are extracted from substrate meshing applying the finite difference method. This model is derived from a linearization of drift-diffusion equations and not from the closed form solution. Further, the proposed circuit is solved with available SPICE simulators because of electrical analogies with physical quantities. Spice simulation results are compared with device simulator results. The accuracy of the model is dependent on the number of the discretization elements used. The Minority carrier diffusion current is included automatically in the total substrate current computation.

Yoshiaki Hara - One of the best experts on this subject based on the ideXlab platform.

  • lifetime and diffusion length of photogenerated Minority Carriers in single crystalline n type β fesi2 bulk
    Applied Physics Letters, 2008
    Co-Authors: Teruhisa Ootsuka, Takashi Suemasu, Jun Chen, Takashi Sekiguchi, Yoshiaki Hara
    Abstract:

    We have evaluated the lifetime and diffusion length of photogenerated Minority Carriers (holes) in single-crystalline n-type β-FeSi2 bulk grown by chemical vapor transport. The diffusion length measured by optical-beam-induced current agreed well with that measured by electron-beam-induced current, that is, 51 and 38μm, respectively, for samples annealed at 800°C for 8h. The decay curve of photoconductivity obtained by 1.31 and 1.55μm light pulses was well fitted by assuming a carrier lifetime of approximately a few microseconds. The mobility of photogenerated Minority Carriers was estimated to be approximately 200–360cm2∕Vs from the measured lifetime and diffusion length.

Maher Kayal - One of the best experts on this subject based on the ideXlab platform.

  • methodology for 3 d substrate network extraction for spice simulation of parasitic currents in smart power ics
    IEEE Transactions on Computer-Aided Design of Integrated Circuits and Systems, 2016
    Co-Authors: Pietro Buccella, Yasser Moursy, Ramy Iskander, Hao Zou, Camillo Stefanucci, Jeanmichel Sallese, Maher Kayal
    Abstract:

    A 3-D simulation of substrate currents is crucial to analyze parasitic coupling effects due to Minority carrier injection in smart power ICs. In this paper, a substrate parasitic extraction methodology is introduced by dividing the IC layout into elementary elements to solve the continuity equation for Minority Carriers in the volume based on the finite-difference method. A substrate parasitic network is derived from the mesh generated through the existing mixed-signal design flow. The induced substrate model is included in circuit simulators such as SPICE to predict the effects of substrate couplings during the design phase. Furthermore, this analysis enables optimization of layout with minimal parasitic effects. By linking the substrate model to the active components, the couplings between the integrated circuit with the substrate parasitic currents can be analyzed during circuit simulations. Simulations and measurements on an high voltage driver reveal consistent results and therefore confirm the validity of the method. Therefore, the approach developed herein is effective to predict parasitic couplings due the injection of Minority Carriers.

  • spice compatible modeling of high injection and propagation of Minority Carriers in the substrate of smart power ics
    Solid-state Electronics, 2015
    Co-Authors: Camillo Stefanucci, Pietro Buccella, Maher Kayal, Jeanmichel Sallese
    Abstract:

    Abstract Classical substrate noise analysis considers the silicon resistivity of an integrated circuit only as doping dependent besides neglecting diffusion currents as well. In power circuits Minority Carriers are injected into the substrate and propagate by drift–diffusion. In this case the conductivity of the substrate is spatially modulated and this effect is particularly important in high injection regime. In this work a description of the coupling between majority and Minority drift–diffusion currents is presented. A distributed model of the substrate is then proposed to take into account the conductivity modulation and its feedback on diffusion processes. The model is expressed in terms of equivalent circuits in order to be fully compatible with circuit simulators. The simulation results are then discussed for diodes and bipolar transistors and compared to the ones obtained from physical device simulations and measurements.

  • modeling Minority Carriers related capacitive effects for transient substrate currents in smart power ics
    IEEE Transactions on Electron Devices, 2015
    Co-Authors: Camillo Stefanucci, Pietro Buccella, Maher Kayal, Jeanmichel Sallese
    Abstract:

    This paper presents an extended model for transient and ac circuit-level simulation of Minority Carriers propagation through the substrate of smart power integrated circuits (ICs). A p-n junction and a diffusion resistor with capacitive components are proposed to efficiently simulate transient parasitic coupled currents in high-power stages. From a general chip layout, an equivalent substrate network including capacitive effects (junction and diffusion capacitances) can be extracted and parasitic bipolar transistor can be simulated for the first time in transient operation by circuit simulators once the Minority Carriers continuity conditions are satisfied. This paper shows simulation results of the implemented models in good agreement with those obtained from technology computer-aided design. This implies that transient layout dependent mechanisms between high-voltage aggressor wells and low-voltage victims can be verified in early stages of IC design flow.

  • impact of enhanced contact doping on Minority Carriers diffusion currents
    Conference on Ph.D. Research in Microelectronics and Electronics, 2014
    Co-Authors: Camillo Stefanucci, Pietro Buccella, Maher Kayal, Jeanmichel Sallese
    Abstract:

    Minority Carriers diffusion currents are particularly important in parasitic substrate couplings of Smart Power ICs. In CMOS technologies the P-substrate potential is imposed by P+ contacts and N-wells by N+ highly doped implantations. The doping concentration discontinuity of these contact regions can have a big impact on parasitic diffusion currents of Minority Carriers. This work gives a description of these effects by device physical simulations of PN junctions under different injection levels of Minority Carriers. The perturbation of boundary conditions for electrons diffusion is also studied inside the substrate bulk in case a highly-doped substrate is used for high-voltage technologies.

  • spice simulation of substrate Minority Carriers propagation with equivalent electrical circuit
    International Conference Mixed Design of Integrated Circuits and Systems, 2014
    Co-Authors: Pietro Buccella, Camillo Stefanucci, Jeanmichel Sallese, Maher Kayal
    Abstract:

    This paper presents an equivalent electrical circuit for one dimensional substrate Minority Carriers spice simulation. The electrical circuit parameters are extracted from substrate meshing applying the finite difference method. This model is derived from a linearization of drift-diffusion equations and not from the closed form solution. Further, the proposed circuit is solved with available SPICE simulators because of electrical analogies with physical quantities. Spice simulation results are compared with device simulator results. The accuracy of the model is dependent on the number of the discretization elements used. The Minority carrier diffusion current is included automatically in the total substrate current computation.

Eric A. Kittlaus - One of the best experts on this subject based on the ideXlab platform.

  • Diffusion of degenerate Minority Carriers in a p-type semiconductor
    Journal of Applied Physics, 2013
    Co-Authors: Christopher Weber, Eric A. Kittlaus
    Abstract:

    We report ultrafast transient-grating experiments on heavily p-type InP at 15 K. Our measurement reveals the dynamics and diffusion of photoexcited electrons and holes as a function of their density n in the range 2E16 to 6E17 cm-3. After the first few picoseconds the grating decays primarily due to ambipolar diffusion. While at low density we observe a regime in which the ambipolar diffusion is electron-dominated and increases rapidly with n, at high n it appears to saturate at 34 cm2/s. We present a simple calculation that reproduces the main results of our measurements as well as of previously published measurements that had shown diffusion to be a flat or decreasing function of n. By accounting for effect of density on charge susceptibility we show that, in p-type semiconductors, the regime we observe of increasing ambipolar diffusion is unique to heavy doping and low temperature, where both the holes and electrons are degenerate; in this regime the electronic and ambipolar diffusion are nearly equal. The saturation is identified as a crossover to ambipolar diffusion dominated by the majority Carriers, the holes. At short times the transient-grating signal rises gradually. This rise reveals cooling of hot electrons and, at high photocarrier density, allows us to measure ambipolar diffusion of 110 cm2/s in the hot-carrier regime

  • diffusion of degenerate Minority Carriers in a p type semiconductor
    Journal of Applied Physics, 2013
    Co-Authors: Chris Weber, Eric A. Kittlaus
    Abstract:

    We report ultrafast transient-grating experiments on heavily p-type InP at 15 K. Our measurement reveals the dynamics and diffusion of photoexcited electrons and holes as a function of their density n in the range 2  ×  1016 to 6  ×  1017 cm−3. After the first few picoseconds, the grating decays primarily due to ambipolar diffusion. While, at low density, we observe a regime in which the ambipolar diffusion is electron-dominated and increases rapidly with n, it appears to saturate at 34 cm2/s at high n. We present a simple calculation that reproduces the main results of our measurements as well as of previously published measurements that had shown diffusion to be a flat or decreasing function of n. By accounting for effect of density on charge susceptibility, we show that, in p-type semiconductors, the regime we observe of increasing ambipolar diffusion is unique to heavy doping and low temperature, where both the holes and electrons are degenerate; in this regime, the electronic and ambipolar diffusion are nearly equal. The saturation is identified as a crossover to ambipolar diffusion dominated by the majority Carriers, the holes. At short times, the transient-grating signal rises gradually. This rise reveals cooling of hot electrons and, at high photocarrier density, allows us to measure ambipolar diffusion of 110 cm2/s in the hot-carrier regime.