The Experts below are selected from a list of 234 Experts worldwide ranked by ideXlab platform

Kannan Ramanathan - One of the best experts on this subject based on the ideXlab platform.

  • Charge-carrier dynamics in polycrystalline thin-film CuIn1−xGaxSe2 photovoltaic devices after pulsed laser excitation: Interface and Space-Charge Region analysis
    Journal of Applied Physics, 2015
    Co-Authors: Darius Kuciauskas, Ana Kanevce, Harvey Guthrey, Miguel A. Contreras, Joel Pankow, Pat Dippo, Kannan Ramanathan
    Abstract:

    We used time-resolved photoluminescence (TRPL) spectroscopy to analyze time-domain and spectral-domain Charge-carrier dynamics in CuIn1−xGaxSe2 (CIGS) photovoltaic (PV) devices. This new approach allowed detailed characterization for the CIGS/CdS buffer interface and for the Space-Charge Region. We find that dynamics at the interface is dominated by diffusion, where the diffusion rate is several times greater than the thermionic emission or interface recombination rate. In the Space-Charge Region, the electric field of the pn junction has the largest effect on the carrier dynamics. Based on the minority-carrier (electron) drift-rate dependence on the electric field strength, we estimated drift mobility in compensated CuIn1−xGaxSe2 (with x ≈ 0.3) as 22 ± 2 cm2(Vs)−1. Analysis developed in this study could be applied to evaluate interface and junction properties of PV and other electronic devices. For CIGS PV devices, TRPL spectroscopy could contribute to understanding effects due to absorber compositional ...

  • Charge carrier dynamics in polycrystalline thin film cuin1 xgaxse2 photovoltaic devices after pulsed laser excitation interface and Space Charge Region analysis
    Journal of Applied Physics, 2015
    Co-Authors: Darius Kuciauskas, Ana Kanevce, Harvey Guthrey, Miguel A. Contreras, Joel Pankow, Pat Dippo, Kannan Ramanathan
    Abstract:

    We used time-resolved photoluminescence (TRPL) spectroscopy to analyze time-domain and spectral-domain Charge-carrier dynamics in CuIn1−xGaxSe2 (CIGS) photovoltaic (PV) devices. This new approach allowed detailed characterization for the CIGS/CdS buffer interface and for the Space-Charge Region. We find that dynamics at the interface is dominated by diffusion, where the diffusion rate is several times greater than the thermionic emission or interface recombination rate. In the Space-Charge Region, the electric field of the pn junction has the largest effect on the carrier dynamics. Based on the minority-carrier (electron) drift-rate dependence on the electric field strength, we estimated drift mobility in compensated CuIn1−xGaxSe2 (with x ≈ 0.3) as 22 ± 2 cm2(Vs)−1. Analysis developed in this study could be applied to evaluate interface and junction properties of PV and other electronic devices. For CIGS PV devices, TRPL spectroscopy could contribute to understanding effects due to absorber compositional ...

Rolf Brendel - One of the best experts on this subject based on the ideXlab platform.

  • Space-Charge Region-dominated steady-state photoconductance in low-lifetime Si wafers
    Applied Physics Letters, 2003
    Co-Authors: Michael Bail, Max J. Schulz, Rolf Brendel
    Abstract:

    We investigate the steady-state photoconductance of an oxidized low-lifetime monocrystalline Si wafer with an inversion layer at its surfaces. Photogenerated electrons and holes reduce the band bending and decrease the width of the carrier depleted Space-Charge Region. Mobile Charge carriers are stored on both sides of the Space-Charge Region and dominate the photoconductivity at a low illumination intensity. This Charge storage effect disappears under accumulation. We present an analytic model for the experimental observations. It is necessary to account for the Charge storage effect when deducing low (

  • Space Charge Region dominated steady state photoconductance in low lifetime si wafers
    Applied Physics Letters, 2003
    Co-Authors: Michael Bail, M Schulz, Rolf Brendel
    Abstract:

    We investigate the steady-state photoconductance of an oxidized low-lifetime monocrystalline Si wafer with an inversion layer at its surfaces. Photogenerated electrons and holes reduce the band bending and decrease the width of the carrier depleted Space-Charge Region. Mobile Charge carriers are stored on both sides of the Space-Charge Region and dominate the photoconductivity at a low illumination intensity. This Charge storage effect disappears under accumulation. We present an analytic model for the experimental observations. It is necessary to account for the Charge storage effect when deducing low (<10 μs) minority carrier lifetimes on surface-inverted solar Si wafers from one-sun steady-state photoconductance measurements.

Darius Kuciauskas - One of the best experts on this subject based on the ideXlab platform.

  • Charge-carrier dynamics in polycrystalline thin-film CuIn1−xGaxSe2 photovoltaic devices after pulsed laser excitation: Interface and Space-Charge Region analysis
    Journal of Applied Physics, 2015
    Co-Authors: Darius Kuciauskas, Ana Kanevce, Harvey Guthrey, Miguel A. Contreras, Joel Pankow, Pat Dippo, Kannan Ramanathan
    Abstract:

    We used time-resolved photoluminescence (TRPL) spectroscopy to analyze time-domain and spectral-domain Charge-carrier dynamics in CuIn1−xGaxSe2 (CIGS) photovoltaic (PV) devices. This new approach allowed detailed characterization for the CIGS/CdS buffer interface and for the Space-Charge Region. We find that dynamics at the interface is dominated by diffusion, where the diffusion rate is several times greater than the thermionic emission or interface recombination rate. In the Space-Charge Region, the electric field of the pn junction has the largest effect on the carrier dynamics. Based on the minority-carrier (electron) drift-rate dependence on the electric field strength, we estimated drift mobility in compensated CuIn1−xGaxSe2 (with x ≈ 0.3) as 22 ± 2 cm2(Vs)−1. Analysis developed in this study could be applied to evaluate interface and junction properties of PV and other electronic devices. For CIGS PV devices, TRPL spectroscopy could contribute to understanding effects due to absorber compositional ...

  • Charge carrier dynamics in polycrystalline thin film cuin1 xgaxse2 photovoltaic devices after pulsed laser excitation interface and Space Charge Region analysis
    Journal of Applied Physics, 2015
    Co-Authors: Darius Kuciauskas, Ana Kanevce, Harvey Guthrey, Miguel A. Contreras, Joel Pankow, Pat Dippo, Kannan Ramanathan
    Abstract:

    We used time-resolved photoluminescence (TRPL) spectroscopy to analyze time-domain and spectral-domain Charge-carrier dynamics in CuIn1−xGaxSe2 (CIGS) photovoltaic (PV) devices. This new approach allowed detailed characterization for the CIGS/CdS buffer interface and for the Space-Charge Region. We find that dynamics at the interface is dominated by diffusion, where the diffusion rate is several times greater than the thermionic emission or interface recombination rate. In the Space-Charge Region, the electric field of the pn junction has the largest effect on the carrier dynamics. Based on the minority-carrier (electron) drift-rate dependence on the electric field strength, we estimated drift mobility in compensated CuIn1−xGaxSe2 (with x ≈ 0.3) as 22 ± 2 cm2(Vs)−1. Analysis developed in this study could be applied to evaluate interface and junction properties of PV and other electronic devices. For CIGS PV devices, TRPL spectroscopy could contribute to understanding effects due to absorber compositional ...

J. Toušek - One of the best experts on this subject based on the ideXlab platform.

  • The role of the Space Charge Region in surface photovoltaic effect
    Journal of Applied Physics, 2014
    Co-Authors: J. Toušek, J. Toušková
    Abstract:

    The surface photovoltage method is an important tool for semiconductor characterization. Evaluation of photocarrier diffusion length represents one of the most essential applications of this method. The technique is usually limited to samples with thick neutral bulk and thin Space Charge Region (SCR) at the illuminated surface. The purpose of this paper is to remove these restrictions by introducing a more general model. Two different transport processes for the photogenerated carriers are assumed: drift in the SCR and diffusion in the neutral bulk. It was found that the SCR and the bulk contribute to the overall signal independently even in the case of recombination in the depletion Region. The presented surface photovoltage technique was successfully applied to samples of different thickness and with differently thick Space Charge Region at the surface. The diffusion length of the minority carrier in inorganic semiconductors as well as the diffusion length of excitons in organic materials were extracted. The thickness of the Space Charge Region is another important parameter obtained by using the model.

  • surface photovoltaic effect in cdte as influenced by recombination in the Space Charge Region
    Physica Status Solidi (a), 2007
    Co-Authors: J. Toušek, J. Toušková, Eduard Belas, L. Votoček
    Abstract:

    Diffusion length of minority carriers in CdTe wafers was measured by the surface photovoltage (SPV) method. A model including recombination in the Space-Charge Region (SCR) is presented to explain the SPV spectra. Assuming a thick neutral bulk and an electric field only in the SCR, five parameters are needed for characterization of the system. On analyzing the problem we have found that the most important of them – the diffusion length of minority carriers L – is not influenced by recombination in the SCR. The results are verified on samples with different resistivities, and extracted diffusion length is compared with literature data. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

  • Surface photovoltaic effect in CdTe as influenced by recombination in the Space‐Charge Region
    physica status solidi (a), 2007
    Co-Authors: J. Toušek, J. Toušková, Eduard Belas, L. Votoček
    Abstract:

    Diffusion length of minority carriers in CdTe wafers was measured by the surface photovoltage (SPV) method. A model including recombination in the Space-Charge Region (SCR) is presented to explain the SPV spectra. Assuming a thick neutral bulk and an electric field only in the SCR, five parameters are needed for characterization of the system. On analyzing the problem we have found that the most important of them – the diffusion length of minority carriers L – is not influenced by recombination in the SCR. The results are verified on samples with different resistivities, and extracted diffusion length is compared with literature data. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

  • Surface photovoltage measurements in μc-Si:H: Manifestation of the bottom Space Charge Region
    Journal of Applied Physics, 2002
    Co-Authors: Vladimir Svrcek, J. Toušek, Ivan Pelant, P. Fojtı́k, Jan Kočka, Antonín Fejfar, Michio Kondo, Akihisa Matsuda
    Abstract:

    We discuss results of surface photovoltage (U) measurements for d=10 μm thick layers of undoped hydrogenated microcrystalline silicon (μc-Si:H). By applying excitation with low energetic photons (down to 1.1 eV), i.e., with small absorption coefficient α and a large penetration depth α−1, a photovoltage peak appears on a curve U=U(α). This peak is located at α≳d−1 and its occurrence depends critically on the substrate material. The peak is present in a μc-Si:H film grown on p+ crystalline silicon (c-Si), on the other hand it is missing in the μc-Si:H samples grown on n+ c-Si or ZnO film. We present a mathematical model that enables us to link this peak to photoCharge separation in the bottom Space Charge Region at the interface μc-Si:H/substrate. Besides the magnitude of the ambipolar carrier diffusion length L, a parameter particularly critical for the occurrence of the peak turns out to be the ratio n of reverse saturation current densities of the two diodes representing surface and bottom Space Charge ...

  • Photovoltaic Effect in Heterojunctions with Recombination in the Space Charge Region
    Physica Status Solidi (a), 1993
    Co-Authors: J. Toušek
    Abstract:

    The theory of the photovoltaic effect is generalized taking into account the recombination in the Space Charge Region. The results are applied to the heterojunction CdS/CdTe and compared with experiment. La theorie d'effet photovoltaique est generalisee en comprenant la recombinaison dans la Region de Charge d'eSpace. Les resultats sont appliques sur les heterojonctions CdS/CdTe et compares avec l'expereiment.

Michael Bail - One of the best experts on this subject based on the ideXlab platform.

  • Space-Charge Region-dominated steady-state photoconductance in low-lifetime Si wafers
    Applied Physics Letters, 2003
    Co-Authors: Michael Bail, Max J. Schulz, Rolf Brendel
    Abstract:

    We investigate the steady-state photoconductance of an oxidized low-lifetime monocrystalline Si wafer with an inversion layer at its surfaces. Photogenerated electrons and holes reduce the band bending and decrease the width of the carrier depleted Space-Charge Region. Mobile Charge carriers are stored on both sides of the Space-Charge Region and dominate the photoconductivity at a low illumination intensity. This Charge storage effect disappears under accumulation. We present an analytic model for the experimental observations. It is necessary to account for the Charge storage effect when deducing low (

  • Space Charge Region dominated steady state photoconductance in low lifetime si wafers
    Applied Physics Letters, 2003
    Co-Authors: Michael Bail, M Schulz, Rolf Brendel
    Abstract:

    We investigate the steady-state photoconductance of an oxidized low-lifetime monocrystalline Si wafer with an inversion layer at its surfaces. Photogenerated electrons and holes reduce the band bending and decrease the width of the carrier depleted Space-Charge Region. Mobile Charge carriers are stored on both sides of the Space-Charge Region and dominate the photoconductivity at a low illumination intensity. This Charge storage effect disappears under accumulation. We present an analytic model for the experimental observations. It is necessary to account for the Charge storage effect when deducing low (<10 μs) minority carrier lifetimes on surface-inverted solar Si wafers from one-sun steady-state photoconductance measurements.