The Experts below are selected from a list of 216 Experts worldwide ranked by ideXlab platform
Simon Fafard - One of the best experts on this subject based on the ideXlab platform.
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Challenges and strategies for implementing the vertical Epitaxial Heterostructure architechture (VEHSA) design for concentrated photovoltaic applications
Solar Energy Materials and Solar Cells, 2018Co-Authors: Mark C. A. York, Richard Arès, Vincent Aimez, Antoine Mailhot, Abderraouf Boucherif, Simon FafardAbstract:Monochromatic conversion efficiencies in excess of 60% have been achieved with Vertical Epitaxial Heterostructure Architechture laser power converters (with anywhere from 5 to 20+ n/p junctions stacked vertically). We are presently investigating the applicability of this design to solar cells, whereby the individual junctions of a multi-junction cell are replaced with a current matched stack of subcells. If viable, such a design offers the potential for efficiency gains via reduced I R 2 losses and elevated V oc. Moreover, splitting the short-circuit current over additional junctions opens up the possibility of operation under concentration ratios otherwise considered impractical for conventional cells.
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High efficiency phototransducers based on a novel vertical Epitaxial Heterostructure architecture (VEHSA) with thin p/n junctions
Journal of Physics D: Applied Physics, 2017Co-Authors: Mark York, Simon FafardAbstract:This review outlines a series of developments in the design, modelling and growth of multi-junction laser power converters, including several observations of multi-junction GaAs monolithic vertical Epitaxial Heterostructure architecture devices with astonishing mono-chromatic optical to electrical conversion efficiencies in the 65–70% range. Experimental data is presented for devices ranging from single up to 20 p/n junctions, generally exhibiting weak dependence on source detuning which serves as evidence for strong photon recycling effects in these devices. Considerations for further design optimizations are discussed in detail, as well as the future direction of this research including the growth of devices with up to 100 subcells.
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Measurement of strong photon recycling in ultra-thin GaAs n/p junctions monolithically integrated in high-photovoltage vertical Epitaxial Heterostructure architectures with conversion efficiencies exceeding 60%
physica status solidi (RRL) - Rapid Research Letters, 2016Co-Authors: F. Proulx, Mark C. A. York, Richard Arès, Vincent Aimez, Denis Masson, Philippe-olivier Provost, Simon FafardAbstract:Photon-recycling effects are studied experimentally in photovoltaic power converting III–V semiconductor devices designed with the vertical Epitaxial Heterostructure architecture (VEHSA). The responsivity of VEHSA structures with multiple thin GaAs n/p junctions is measured for various optical input powers and for different wavelength detuning values with respect to the peak of the spectral response. While the detuning of the optical excitation decreases the external quantum efficiency and the responsivity at low input powers, this study demonstrates that at high optical intensities, a large fraction of the performance can be recovered despite significant detuning values. The photon coupling effects therefore broaden the spectral range for which the VEHSA devices convert high-power optical inputs with high efficiencies into an electrical output having a preset voltage. The devices exhibit a near optimum responsivity of up to 0.645 A/W for tuned excitation conditions or at high optical intensities for spectral detuning values of up to ∼25 nm and corresponding to an external quantum efficiency of ∼94%. Efficiencies of 62.0% and 61.8% have been obtained for current-matched excitations and for a detuning of >10 nm, respectively. An output power of 5.87 W is reported and an open circuit voltage enhancement of 92 meV per n/p junction is measured compared to a device with a side by side planar architecture. (© 2016 WILEY-VCH Verlag GmbH &Co. KGaA, Weinheim)
Denis Masson - One of the best experts on this subject based on the ideXlab platform.
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Measurement of strong photon recycling in ultra-thin GaAs n/p junctions monolithically integrated in high-photovoltage vertical Epitaxial Heterostructure architectures with conversion efficiencies exceeding 60%
physica status solidi (RRL) - Rapid Research Letters, 2016Co-Authors: F. Proulx, Mark C. A. York, Richard Arès, Vincent Aimez, Denis Masson, Philippe-olivier Provost, Simon FafardAbstract:Photon-recycling effects are studied experimentally in photovoltaic power converting III–V semiconductor devices designed with the vertical Epitaxial Heterostructure architecture (VEHSA). The responsivity of VEHSA structures with multiple thin GaAs n/p junctions is measured for various optical input powers and for different wavelength detuning values with respect to the peak of the spectral response. While the detuning of the optical excitation decreases the external quantum efficiency and the responsivity at low input powers, this study demonstrates that at high optical intensities, a large fraction of the performance can be recovered despite significant detuning values. The photon coupling effects therefore broaden the spectral range for which the VEHSA devices convert high-power optical inputs with high efficiencies into an electrical output having a preset voltage. The devices exhibit a near optimum responsivity of up to 0.645 A/W for tuned excitation conditions or at high optical intensities for spectral detuning values of up to ∼25 nm and corresponding to an external quantum efficiency of ∼94%. Efficiencies of 62.0% and 61.8% have been obtained for current-matched excitations and for a detuning of >10 nm, respectively. An output power of 5.87 W is reported and an open circuit voltage enhancement of 92 meV per n/p junction is measured compared to a device with a side by side planar architecture. (© 2016 WILEY-VCH Verlag GmbH &Co. KGaA, Weinheim)
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high photovoltage gaas vertical Epitaxial monolithic Heterostructures with 20 thin p n junctions and a conversion efficiency of 60
Applied Physics Letters, 2016Co-Authors: S. Fafard, Mark C. A. York, F. Proulx, Richard Arès, Vincent Aimez, Philippe-olivier Provost, L S Richard, Denis MassonAbstract:Photovoltaic power converting III–V semiconductor devices based on the Vertical Epitaxial Heterostructure Architecture (VEHSA) design have been achieved with up to 20 thin p/n junctions (PT20). Open circuit photovoltages in excess of 23 V are measured for a continuous wave monochromatic optical input power of ∼1 W tuned in the 750 nm–875 nm wavelength range. Conversion efficiencies greater than 60% are demonstrated when the PT20 devices are measured near the peak of their spectral response. Noticeably, the PT20 structure is implemented with its narrowest ultrathin base having a thickness of only 24 nm. In the present study, the spectral response of the PT20 peaks at external quantum efficiency (EQE) of 89%/20 for an input wavelength of 841 nm. We also performed a detailed analysis of the EQE dependence with temperature and for VEHSA structures realised with a varied number of p/n junctions. The systematic study reveals the correlations between the measured conversion efficiencies, the EQE behavior, and th...
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Ultrahigh efficiencies in vertical Epitaxial Heterostructure architectures
Applied Physics Letters, 2016Co-Authors: S. Fafard, Mark C. A. York, F. Proulx, Valdivia Christopher, Matthew M. Wilkins, Richard Arès, Vincent Aimez, Karin Hinzer, Denis MassonAbstract:Optical to electrical power converting semiconductor devices were achieved with breakthrough performance by designing a Vertical Epitaxial Heterostructure Architecture. The devices are featuring modeled and measured conversion efficiencies greater than 65%. The ultrahigh conversion efficiencies were obtained by monolithically integrating several thin GaAs photovoltaic junctions tailored with submicron absorption thicknesses and grown in a single crystal by epitaxy. The Heterostructures that were engineered with a number N of such ultrathin junctions yielded an optimal external quantum efficiencies approaching 100%/N. The Heterostructures are capable of output voltages that are multiple times larger than the corresponding photovoltage of the input light. The individual nanoscale junctions are each generating up to ∼1.2 V of output voltage when illuminated in the infrared. We compare the optoelectronic properties of phototransducers prepared with designs having 5 to 12 junctions and that are exhibiting volt...
Mark C. A. York - One of the best experts on this subject based on the ideXlab platform.
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Challenges and strategies for implementing the vertical Epitaxial Heterostructure architechture (VEHSA) design for concentrated photovoltaic applications
Solar Energy Materials and Solar Cells, 2018Co-Authors: Mark C. A. York, Richard Arès, Vincent Aimez, Antoine Mailhot, Abderraouf Boucherif, Simon FafardAbstract:Monochromatic conversion efficiencies in excess of 60% have been achieved with Vertical Epitaxial Heterostructure Architechture laser power converters (with anywhere from 5 to 20+ n/p junctions stacked vertically). We are presently investigating the applicability of this design to solar cells, whereby the individual junctions of a multi-junction cell are replaced with a current matched stack of subcells. If viable, such a design offers the potential for efficiency gains via reduced I R 2 losses and elevated V oc. Moreover, splitting the short-circuit current over additional junctions opens up the possibility of operation under concentration ratios otherwise considered impractical for conventional cells.
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Measurement of strong photon recycling in ultra-thin GaAs n/p junctions monolithically integrated in high-photovoltage vertical Epitaxial Heterostructure architectures with conversion efficiencies exceeding 60%
physica status solidi (RRL) - Rapid Research Letters, 2016Co-Authors: F. Proulx, Mark C. A. York, Richard Arès, Vincent Aimez, Denis Masson, Philippe-olivier Provost, Simon FafardAbstract:Photon-recycling effects are studied experimentally in photovoltaic power converting III–V semiconductor devices designed with the vertical Epitaxial Heterostructure architecture (VEHSA). The responsivity of VEHSA structures with multiple thin GaAs n/p junctions is measured for various optical input powers and for different wavelength detuning values with respect to the peak of the spectral response. While the detuning of the optical excitation decreases the external quantum efficiency and the responsivity at low input powers, this study demonstrates that at high optical intensities, a large fraction of the performance can be recovered despite significant detuning values. The photon coupling effects therefore broaden the spectral range for which the VEHSA devices convert high-power optical inputs with high efficiencies into an electrical output having a preset voltage. The devices exhibit a near optimum responsivity of up to 0.645 A/W for tuned excitation conditions or at high optical intensities for spectral detuning values of up to ∼25 nm and corresponding to an external quantum efficiency of ∼94%. Efficiencies of 62.0% and 61.8% have been obtained for current-matched excitations and for a detuning of >10 nm, respectively. An output power of 5.87 W is reported and an open circuit voltage enhancement of 92 meV per n/p junction is measured compared to a device with a side by side planar architecture. (© 2016 WILEY-VCH Verlag GmbH &Co. KGaA, Weinheim)
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high photovoltage gaas vertical Epitaxial monolithic Heterostructures with 20 thin p n junctions and a conversion efficiency of 60
Applied Physics Letters, 2016Co-Authors: S. Fafard, Mark C. A. York, F. Proulx, Richard Arès, Vincent Aimez, Philippe-olivier Provost, L S Richard, Denis MassonAbstract:Photovoltaic power converting III–V semiconductor devices based on the Vertical Epitaxial Heterostructure Architecture (VEHSA) design have been achieved with up to 20 thin p/n junctions (PT20). Open circuit photovoltages in excess of 23 V are measured for a continuous wave monochromatic optical input power of ∼1 W tuned in the 750 nm–875 nm wavelength range. Conversion efficiencies greater than 60% are demonstrated when the PT20 devices are measured near the peak of their spectral response. Noticeably, the PT20 structure is implemented with its narrowest ultrathin base having a thickness of only 24 nm. In the present study, the spectral response of the PT20 peaks at external quantum efficiency (EQE) of 89%/20 for an input wavelength of 841 nm. We also performed a detailed analysis of the EQE dependence with temperature and for VEHSA structures realised with a varied number of p/n junctions. The systematic study reveals the correlations between the measured conversion efficiencies, the EQE behavior, and th...
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advances with vertical Epitaxial Heterostructure architecture vehsa phototransducers for optical to electrical power conversion efficiencies exceeding 50 percent
Proceedings of SPIE, 2016Co-Authors: S. Fafard, Mark C. A. York, F. Proulx, Matthew M. Wilkins, Christopher E Valdivia, Michal Bajcsy, Dayan Ban, Abdelatif Jaouad, Boussairi Bouzazi, Richard ArèsAbstract:A monolithic compound semiconductor phototransducer optimized for narrow-band light sources was designed for and has achieved conversion efficiencies exceeding 50%. The III-V Heterostructure was grown by MOCVD, based on the vertical stacking of a number of partially absorbing GaAs n/p junctions connected in series with tunnel junctions. The thicknesses of the p-type base layers of the diodes were engineered for optimal absorption and current matching for an optical input with wavelengths centered in the 830 nm to 850 nm range. The device architecture allows for improved open-circuit voltage in the individual base segments due to efficient carrier extraction while simultaneously maintaining a complete absorption of the input photons with no need for complicated fabrication processes or reflecting layers. Progress for device outputs achieving in excess of 12 V is reviewed in this study.
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Thin n/p GaAs Junctions for Novel High-Efficiency Phototransducers Based on a Vertical Epitaxial Heterostructure Architecture
MRS Advances, 2016Co-Authors: Mark C. A. York, F. Proulx, Richard Arès, Vincent Aimez, D. P. Masson, A. Jaouad, B. Bouzazi, S. FafardAbstract:Thin GaAs photovoltaic Heterostructures are grown by MOCVD with various p-GaAs base thicknesses. The total n/p absorbing thickness is varied systematically. Output voltages up to ~1.155V were obtained for individual n/p junctions at an average illumination intensity of ~8W/cm^2. Novel phototransducer devices are then achieved with a vertical Epitaxial Heterostructure architecture, monolithically integrating 5 or more such thin n/p junctions. Around the design wavelength, the stacked Heterostructure design is yielding an optimal external quantum efficiency approaching unity divided by the number of junctions. The modeled and measured conversion efficiencies are exceeding 60%. The photocarrier extraction properties are simulated for different junction thicknesses using a model based on a 3-dimensional (3D) radially-symmetric TCAD implementation of the Heterostructures. The study clearly demonstrates that for such thin n/p junctions the photocarrier extraction can still be efficient due to the operation at reduced current densities and higher voltages in Heterostructures enhancing electrical power extraction. With the supplementary add-on of a window layer with a reduced sheet resistance for the stacked structure, we demonstrate the possible efficient operation of phototransducers for optical inputs exceeding 150 W/cm^2, even for the case of devices designed without gridlines.
Richard Arès - One of the best experts on this subject based on the ideXlab platform.
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Challenges and strategies for implementing the vertical Epitaxial Heterostructure architechture (VEHSA) design for concentrated photovoltaic applications
Solar Energy Materials and Solar Cells, 2018Co-Authors: Mark C. A. York, Richard Arès, Vincent Aimez, Antoine Mailhot, Abderraouf Boucherif, Simon FafardAbstract:Monochromatic conversion efficiencies in excess of 60% have been achieved with Vertical Epitaxial Heterostructure Architechture laser power converters (with anywhere from 5 to 20+ n/p junctions stacked vertically). We are presently investigating the applicability of this design to solar cells, whereby the individual junctions of a multi-junction cell are replaced with a current matched stack of subcells. If viable, such a design offers the potential for efficiency gains via reduced I R 2 losses and elevated V oc. Moreover, splitting the short-circuit current over additional junctions opens up the possibility of operation under concentration ratios otherwise considered impractical for conventional cells.
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Measurement of strong photon recycling in ultra-thin GaAs n/p junctions monolithically integrated in high-photovoltage vertical Epitaxial Heterostructure architectures with conversion efficiencies exceeding 60%
physica status solidi (RRL) - Rapid Research Letters, 2016Co-Authors: F. Proulx, Mark C. A. York, Richard Arès, Vincent Aimez, Denis Masson, Philippe-olivier Provost, Simon FafardAbstract:Photon-recycling effects are studied experimentally in photovoltaic power converting III–V semiconductor devices designed with the vertical Epitaxial Heterostructure architecture (VEHSA). The responsivity of VEHSA structures with multiple thin GaAs n/p junctions is measured for various optical input powers and for different wavelength detuning values with respect to the peak of the spectral response. While the detuning of the optical excitation decreases the external quantum efficiency and the responsivity at low input powers, this study demonstrates that at high optical intensities, a large fraction of the performance can be recovered despite significant detuning values. The photon coupling effects therefore broaden the spectral range for which the VEHSA devices convert high-power optical inputs with high efficiencies into an electrical output having a preset voltage. The devices exhibit a near optimum responsivity of up to 0.645 A/W for tuned excitation conditions or at high optical intensities for spectral detuning values of up to ∼25 nm and corresponding to an external quantum efficiency of ∼94%. Efficiencies of 62.0% and 61.8% have been obtained for current-matched excitations and for a detuning of >10 nm, respectively. An output power of 5.87 W is reported and an open circuit voltage enhancement of 92 meV per n/p junction is measured compared to a device with a side by side planar architecture. (© 2016 WILEY-VCH Verlag GmbH &Co. KGaA, Weinheim)
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high photovoltage gaas vertical Epitaxial monolithic Heterostructures with 20 thin p n junctions and a conversion efficiency of 60
Applied Physics Letters, 2016Co-Authors: S. Fafard, Mark C. A. York, F. Proulx, Richard Arès, Vincent Aimez, Philippe-olivier Provost, L S Richard, Denis MassonAbstract:Photovoltaic power converting III–V semiconductor devices based on the Vertical Epitaxial Heterostructure Architecture (VEHSA) design have been achieved with up to 20 thin p/n junctions (PT20). Open circuit photovoltages in excess of 23 V are measured for a continuous wave monochromatic optical input power of ∼1 W tuned in the 750 nm–875 nm wavelength range. Conversion efficiencies greater than 60% are demonstrated when the PT20 devices are measured near the peak of their spectral response. Noticeably, the PT20 structure is implemented with its narrowest ultrathin base having a thickness of only 24 nm. In the present study, the spectral response of the PT20 peaks at external quantum efficiency (EQE) of 89%/20 for an input wavelength of 841 nm. We also performed a detailed analysis of the EQE dependence with temperature and for VEHSA structures realised with a varied number of p/n junctions. The systematic study reveals the correlations between the measured conversion efficiencies, the EQE behavior, and th...
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advances with vertical Epitaxial Heterostructure architecture vehsa phototransducers for optical to electrical power conversion efficiencies exceeding 50 percent
Proceedings of SPIE, 2016Co-Authors: S. Fafard, Mark C. A. York, F. Proulx, Matthew M. Wilkins, Christopher E Valdivia, Michal Bajcsy, Dayan Ban, Abdelatif Jaouad, Boussairi Bouzazi, Richard ArèsAbstract:A monolithic compound semiconductor phototransducer optimized for narrow-band light sources was designed for and has achieved conversion efficiencies exceeding 50%. The III-V Heterostructure was grown by MOCVD, based on the vertical stacking of a number of partially absorbing GaAs n/p junctions connected in series with tunnel junctions. The thicknesses of the p-type base layers of the diodes were engineered for optimal absorption and current matching for an optical input with wavelengths centered in the 830 nm to 850 nm range. The device architecture allows for improved open-circuit voltage in the individual base segments due to efficient carrier extraction while simultaneously maintaining a complete absorption of the input photons with no need for complicated fabrication processes or reflecting layers. Progress for device outputs achieving in excess of 12 V is reviewed in this study.
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Thin n/p GaAs Junctions for Novel High-Efficiency Phototransducers Based on a Vertical Epitaxial Heterostructure Architecture
MRS Advances, 2016Co-Authors: Mark C. A. York, F. Proulx, Richard Arès, Vincent Aimez, D. P. Masson, A. Jaouad, B. Bouzazi, S. FafardAbstract:Thin GaAs photovoltaic Heterostructures are grown by MOCVD with various p-GaAs base thicknesses. The total n/p absorbing thickness is varied systematically. Output voltages up to ~1.155V were obtained for individual n/p junctions at an average illumination intensity of ~8W/cm^2. Novel phototransducer devices are then achieved with a vertical Epitaxial Heterostructure architecture, monolithically integrating 5 or more such thin n/p junctions. Around the design wavelength, the stacked Heterostructure design is yielding an optimal external quantum efficiency approaching unity divided by the number of junctions. The modeled and measured conversion efficiencies are exceeding 60%. The photocarrier extraction properties are simulated for different junction thicknesses using a model based on a 3-dimensional (3D) radially-symmetric TCAD implementation of the Heterostructures. The study clearly demonstrates that for such thin n/p junctions the photocarrier extraction can still be efficient due to the operation at reduced current densities and higher voltages in Heterostructures enhancing electrical power extraction. With the supplementary add-on of a window layer with a reduced sheet resistance for the stacked structure, we demonstrate the possible efficient operation of phototransducers for optical inputs exceeding 150 W/cm^2, even for the case of devices designed without gridlines.
Vincent Aimez - One of the best experts on this subject based on the ideXlab platform.
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Challenges and strategies for implementing the vertical Epitaxial Heterostructure architechture (VEHSA) design for concentrated photovoltaic applications
Solar Energy Materials and Solar Cells, 2018Co-Authors: Mark C. A. York, Richard Arès, Vincent Aimez, Antoine Mailhot, Abderraouf Boucherif, Simon FafardAbstract:Monochromatic conversion efficiencies in excess of 60% have been achieved with Vertical Epitaxial Heterostructure Architechture laser power converters (with anywhere from 5 to 20+ n/p junctions stacked vertically). We are presently investigating the applicability of this design to solar cells, whereby the individual junctions of a multi-junction cell are replaced with a current matched stack of subcells. If viable, such a design offers the potential for efficiency gains via reduced I R 2 losses and elevated V oc. Moreover, splitting the short-circuit current over additional junctions opens up the possibility of operation under concentration ratios otherwise considered impractical for conventional cells.
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Measurement of strong photon recycling in ultra-thin GaAs n/p junctions monolithically integrated in high-photovoltage vertical Epitaxial Heterostructure architectures with conversion efficiencies exceeding 60%
physica status solidi (RRL) - Rapid Research Letters, 2016Co-Authors: F. Proulx, Mark C. A. York, Richard Arès, Vincent Aimez, Denis Masson, Philippe-olivier Provost, Simon FafardAbstract:Photon-recycling effects are studied experimentally in photovoltaic power converting III–V semiconductor devices designed with the vertical Epitaxial Heterostructure architecture (VEHSA). The responsivity of VEHSA structures with multiple thin GaAs n/p junctions is measured for various optical input powers and for different wavelength detuning values with respect to the peak of the spectral response. While the detuning of the optical excitation decreases the external quantum efficiency and the responsivity at low input powers, this study demonstrates that at high optical intensities, a large fraction of the performance can be recovered despite significant detuning values. The photon coupling effects therefore broaden the spectral range for which the VEHSA devices convert high-power optical inputs with high efficiencies into an electrical output having a preset voltage. The devices exhibit a near optimum responsivity of up to 0.645 A/W for tuned excitation conditions or at high optical intensities for spectral detuning values of up to ∼25 nm and corresponding to an external quantum efficiency of ∼94%. Efficiencies of 62.0% and 61.8% have been obtained for current-matched excitations and for a detuning of >10 nm, respectively. An output power of 5.87 W is reported and an open circuit voltage enhancement of 92 meV per n/p junction is measured compared to a device with a side by side planar architecture. (© 2016 WILEY-VCH Verlag GmbH &Co. KGaA, Weinheim)
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high photovoltage gaas vertical Epitaxial monolithic Heterostructures with 20 thin p n junctions and a conversion efficiency of 60
Applied Physics Letters, 2016Co-Authors: S. Fafard, Mark C. A. York, F. Proulx, Richard Arès, Vincent Aimez, Philippe-olivier Provost, L S Richard, Denis MassonAbstract:Photovoltaic power converting III–V semiconductor devices based on the Vertical Epitaxial Heterostructure Architecture (VEHSA) design have been achieved with up to 20 thin p/n junctions (PT20). Open circuit photovoltages in excess of 23 V are measured for a continuous wave monochromatic optical input power of ∼1 W tuned in the 750 nm–875 nm wavelength range. Conversion efficiencies greater than 60% are demonstrated when the PT20 devices are measured near the peak of their spectral response. Noticeably, the PT20 structure is implemented with its narrowest ultrathin base having a thickness of only 24 nm. In the present study, the spectral response of the PT20 peaks at external quantum efficiency (EQE) of 89%/20 for an input wavelength of 841 nm. We also performed a detailed analysis of the EQE dependence with temperature and for VEHSA structures realised with a varied number of p/n junctions. The systematic study reveals the correlations between the measured conversion efficiencies, the EQE behavior, and th...
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Thin n/p GaAs Junctions for Novel High-Efficiency Phototransducers Based on a Vertical Epitaxial Heterostructure Architecture
MRS Advances, 2016Co-Authors: Mark C. A. York, F. Proulx, Richard Arès, Vincent Aimez, D. P. Masson, A. Jaouad, B. Bouzazi, S. FafardAbstract:Thin GaAs photovoltaic Heterostructures are grown by MOCVD with various p-GaAs base thicknesses. The total n/p absorbing thickness is varied systematically. Output voltages up to ~1.155V were obtained for individual n/p junctions at an average illumination intensity of ~8W/cm^2. Novel phototransducer devices are then achieved with a vertical Epitaxial Heterostructure architecture, monolithically integrating 5 or more such thin n/p junctions. Around the design wavelength, the stacked Heterostructure design is yielding an optimal external quantum efficiency approaching unity divided by the number of junctions. The modeled and measured conversion efficiencies are exceeding 60%. The photocarrier extraction properties are simulated for different junction thicknesses using a model based on a 3-dimensional (3D) radially-symmetric TCAD implementation of the Heterostructures. The study clearly demonstrates that for such thin n/p junctions the photocarrier extraction can still be efficient due to the operation at reduced current densities and higher voltages in Heterostructures enhancing electrical power extraction. With the supplementary add-on of a window layer with a reduced sheet resistance for the stacked structure, we demonstrate the possible efficient operation of phototransducers for optical inputs exceeding 150 W/cm^2, even for the case of devices designed without gridlines.
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Ultrahigh efficiencies in vertical Epitaxial Heterostructure architectures
Applied Physics Letters, 2016Co-Authors: S. Fafard, Mark C. A. York, F. Proulx, Valdivia Christopher, Matthew M. Wilkins, Richard Arès, Vincent Aimez, Karin Hinzer, Denis MassonAbstract:Optical to electrical power converting semiconductor devices were achieved with breakthrough performance by designing a Vertical Epitaxial Heterostructure Architecture. The devices are featuring modeled and measured conversion efficiencies greater than 65%. The ultrahigh conversion efficiencies were obtained by monolithically integrating several thin GaAs photovoltaic junctions tailored with submicron absorption thicknesses and grown in a single crystal by epitaxy. The Heterostructures that were engineered with a number N of such ultrathin junctions yielded an optimal external quantum efficiencies approaching 100%/N. The Heterostructures are capable of output voltages that are multiple times larger than the corresponding photovoltage of the input light. The individual nanoscale junctions are each generating up to ∼1.2 V of output voltage when illuminated in the infrared. We compare the optoelectronic properties of phototransducers prepared with designs having 5 to 12 junctions and that are exhibiting volt...