The Experts below are selected from a list of 8718 Experts worldwide ranked by ideXlab platform
Aaron J Ptak - One of the best experts on this subject based on the ideXlab platform.
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gallium arsenide solar cells grown at rates exceeding 300 µm h 1 by hydride Vapor Phase Epitaxy
Nature Communications, 2019Co-Authors: Wondwosen Metaferia, Kevin L Schulte, John Simon, Steve Johnston, Aaron J PtakAbstract:We report gallium arsenide (GaAs) growth rates exceeding 300 µm h−1 using dynamic hydride Vapor Phase Epitaxy. We achieved these rates by maximizing the gallium to gallium monochloride conversion efficiency, and by utilizing a mass-transport-limited growth regime with fast kinetics. We also demonstrate gallium indium phosphide growth at rates exceeding 200 µm h−1 using similar growth conditions. We grew GaAs solar cell devices by incorporating the high growth rate of GaAs and evaluated its material quality at these high rates. Solar cell growth rates ranged from 35 to 309 µm h−1 with open circuit voltages ranging from 1.04 to 1.07 V. The best devices exceeded 25% efficiency under the AM1.5 G solar spectrum. The high open-circuit voltages indicate that high material quality can be maintained at these extremely high growth rates. These results have strong implications toward lowering the deposition cost of III-V materials potentially enabling the deposition of high efficiency devices in mere seconds. Gallium arsenide holds record efficiency for single junction solar cells, but high production costs limit applications. Here Metaferia et al. show high quality GaAs and GaInP at rates exceeding 300 and 200 micrometers per hour by dynamic hydride Vapor Phase Epitaxy and > 25% efficient solar cells.
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iii v based optoelectronics with low cost dynamic hydride Vapor Phase Epitaxy
Crystals, 2018Co-Authors: John Simon, Kevin L Schulte, Kelsey A W Horowitz, Timothy Remo, David L Young, Aaron J PtakAbstract:Silicon is the dominant semiconductor in many semiconductor device applications for a variety of reasons, including both performance and cost. III-V materials exhibit improved performance compared to silicon, but currently, they are relegated to applications in high-value or niche markets, due to the absence of a low-cost, high-quality production technique. Here we present an advance in III-V materials synthesis, using a hydride Vapor Phase Epitaxy process that has the potential to lower III-V semiconductor deposition costs, while maintaining the requisite optoelectronic material quality that enables III-V-based technologies to outperform Si. We demonstrate the impacts of this advance by addressing the use of III-Vs in terrestrial photovoltaics, a highly cost-constrained market.
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Upright and Inverted Single-Junction GaAs Solar Cells Grown by Hydride Vapor Phase Epitaxy
IEEE Journal of Photovoltaics, 2017Co-Authors: John Simon, Kevin L Schulte, Steve Johnston, David L Young, Nikhil Jain, Michelle Young, Matthew R. Young, Aaron J PtakAbstract:Hydride Vapor Phase Epitaxy (HVPE) is a low-cost alternative to conventional metal-organic Vapor Phase Epitaxy (MOVPE) growth of III-V solar cells. In this work, we show continued improvement of the performance of HVPE-grown single-junction GaAs solar cells. We show over an order of magnitude improvement in the interface recombination velocity between GaAs and GaInP layers through the elimination of growth interrupts, leading to increased short-circuit current density and open-circuit voltage compared with cells with interrupts. One-sun conversion efficiencies as high as 20.6% were achieved with this improved growth process. Solar cells grown in an inverted configuration that were removed from the substrate showed nearly identical performance to on-wafer cells, demonstrating the viability of HVPE to be used together with conventional wafer reuse techniques for further cost reduction. These devices utilized multiple heterointerfaces, showing the potential of HVPE for the growth of complex and high-quality III-V devices.
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GaAs Solar Cells Grown by Hydride Vapor-Phase Epitaxy and the Development of GaInP Cladding Layers
IEEE Journal of Photovoltaics, 2016Co-Authors: John Simon, Kevin L Schulte, David L Young, Nancy M. Haegel, Aaron J PtakAbstract:The high cost of high-efficiency III-V photovoltaic devices currently limits them to niche markets. Hydride Vapor-Phase Epitaxy (HVPE) growth of III-V materials recently reemerged as a low-cost, high-throughput alternative to conventional metal- organic Vapor-Phase Epitaxy (MOVPE) growth of high-efficiency solar cells. Previously, we demonstrated unpassivated HVPEgrown GaAs p-n junctions with good quantum efficiency and high open-circuit voltage (Voc). In this work, we demonstrate the growth of GaInPby HVPE for use as a high-quality surface passivation layer to GaAs solar cells. Solar cells grown with GaInP window layers show significantly improved quantum efficiency compared with unpassivated cells, increasing the short-circuit current (JSC ) of these low-cost devices. These results show the potential of low-cost HVPE for the growth of high-quality III-V devices.
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low cost iii v solar cells grown by hydride Vapor Phase Epitaxy
Photovoltaic Specialists Conference, 2014Co-Authors: John Simon, David L Young, Aaron J PtakAbstract:The high epitaxial cost of high-efficiency III–V photovoltaic devices has limited these cells to niche markets. In this work, we demonstrate hydride Vapor-Phase Epitaxy (HVPE) growth of III–V materials as a low-cost, high-throughput alternative to conventional metal-organic Vapor-Phase Epitaxy (MOVPE). A brand new, custom-built HVPE reactor was used to obtain high-quality GaAs films at growth rates as high as 1.5 µm/min (90 µm/h). Near-ideal Hall mobilities for both n- and p-type carriers are demonstrated. Preliminary GaAs p-n junctions with unpassivated surfaces show significant rectifying behavior and excellent carrier collection, open-circuit voltage as high as 0.95 V, and fill factors of 86% under AM1.5G illumination. These results show the viability of HVPE for the growth of high-quality III–V devices at significantly lower costs.
Federico Capasso - One of the best experts on this subject based on the ideXlab platform.
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high temperature continuous wave operation of strain balanced quantum cascade lasers grown by metal organic Vapor Phase Epitaxy
Applied Physics Letters, 2006Co-Authors: Laurent Diehl, David P Bour, Scott W Corzine, Mariano Troccoli, Jintian Zhu, Gloria E Hofler, M Loncar, Federico CapassoAbstract:The authors report the fabrication of high-power strained quantum cascade lasers working in continuous mode above 370K. The devices, processed in narrow buried heterostructures, were grown by low-pressure metal organic Vapor-Phase Epitaxy. Continuous wave output power as high as 312mW at 300K was obtained at a wavelength of 5.29μm from a 3.25mm long, 7.5μm wide laser with a high-reflectivity back facet coating. The slope efficiency was in excess of 1.5W∕A and the power conversion efficiency reached almost 5%.
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pulsed and continuous mode operation at high temperature of strained quantum cascade lasers grown by metalorganic Vapor Phase Epitaxy
Applied Physics Letters, 2006Co-Authors: Laurent Diehl, David P Bour, Scott W Corzine, G Hofler, C Y Wang, Mariano Troccoli, Federico CapassoAbstract:We present the pulsed operation at room temperature of different strained InGaAs∕AlInAs quantum-cascade lasers grown by low-pressure metalorganic Vapor-Phase Epitaxy. Devices based on a bound-to-continuum transition design have threshold current densities in pulsed mode as low as 1.84kA∕cm2 at 300K. Identical lasers grown at higher rate (0.5nm∕s) also have threshold current densities lower than 2kA∕cm2 at 300K. Buried heterostructure lasers based on a double phonon resonance design were operated in continuous mode up to 280K. Overall, the performance obtained from strained quantum cascade lasers deposited by metalorganic Vapor-Phase Epitaxy are comparable with that of similar structures grown by molecular beam Epitaxy.
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low threshold continuous wave operation of quantum cascade lasers grown by metalorganic Vapor Phase Epitaxy
Applied Physics Letters, 2004Co-Authors: Mariano Troccoli, Laurent Diehl, David P Bour, Scott W Corzine, G Hofler, Ashish Tandon, D E Mars, David J Smith, Federico CapassoAbstract:We report on the realization of InGaAs∕InAlAs quantum-cascade lasers grown by metalorganic Vapor Phase Epitaxy operating in continuous wave with low-threshold current densities at temperatures as high as 188K. Threshold current densities of 950A∕cm2 and output powers of 125mW are measured at 80K, while 3mW of continuous output power are measured at 180K, with a threshold of 2.5kA∕cm2. In pulsed mode, peak output powers of more than 0.4W were obtained at 80K and of 160mW at 300K with thresholds of 700A∕cm2 and 2.75kA∕cm2, respectively.
R J Molnar - One of the best experts on this subject based on the ideXlab platform.
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evolution of deep centers in gan grown by hydride Vapor Phase Epitaxy
Applied Physics Letters, 2001Co-Authors: Zq Fang, David C Look, Jacek B Jasinski, Mourad Benamara, Z Lilientalweber, R J MolnarAbstract:Deep centers and dislocation densities in undoped n GaN, grown by hydride Vapor Phase Epitaxy (HVPE), were characterized as a function of the layer thickness by deep level transient spectroscopy and transmission electron microscopy, respectively. As the layer thickness decreases, the variety and concentration of deep centers increase, in conjunction with the increase of dislocation density. Based on comparison with electron-irradiation induced centers, some dominant centers in HVPE GaN are identified as possible point defects.
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strain variation with sample thickness in gan grown by hydride Vapor Phase Epitaxy
Journal of Applied Physics, 2000Co-Authors: D C Reynolds, David C Look, B Jogai, J E Hoelscher, R E Sherriff, R J MolnarAbstract:High quality GaN crystals can be grown on sapphire by hydride Vapor Phase Epitaxy. The thermal expansion mismatch between sapphire and GaN produces strain in the GaN crystal as it is cooled from the growth temperature to room temperature. The strain is evidenced by shifts in the photoluminescence and reflectance line positions. By analyzing the surface strain as the crystal thickness is increased, the thickness required to obtain zero surface strain can be estimated. This structure might provide a lattice matched and thermally matched substrate for further epitaxial growth of GaN.
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gan avalanche photodiodes grown by hydride Vapor Phase Epitaxy
Applied Physics Letters, 1999Co-Authors: K A Mcintosh, R J Molnar, L J Mahoney, A Lightfoot, M W Geis, K M Molvar, I Melngailis, R L Aggarwal, W D Goodhue, S S ChoiAbstract:Avalanche photodiodes have been demonstrated utilizing GaN grown by hydride Vapor-Phase Epitaxy. Spatially uniform gain regions were achieved in devices fabricated on low-defect-density GaN layers that exhibit no microplasma behavior. A uniform multiplication gain up to 10 has been measured in the 320–360 nm wavelength range. The external quantum efficiency at unity gain is measured to be 35%. The electric field in the avalanche region has been determined from high-voltage C–V measurements to be ∼1.6 MV/cm at the onset of the multiplication gain. Electric fields as high as 4 MV/cm have been measured in these devices. Response times are found to be less than 5 μs, limited by the measurement system.
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structure of gan films grown by hydride Vapor Phase Epitaxy
Applied Physics Letters, 1997Co-Authors: Linda T Romano, Brent S Krusor, R J MolnarAbstract:The structure of GaN films grown by hydride Vapor Phase Epitaxy on sapphire substrates has been studied by x-ray diffraction, transmission electron microscopy (TEM), and atomic force microscopy. Films, 15–80 μm thick, were grown on c-plane sapphire that were either pretreated with GaCl or contained a ZnO sputter deposited layer. The defect density, for both types of films, was found by plan view TEM to range between mid-107 to mid-108 dislocations/cm2 despite very different structural defects at the film/substrate interface. Nanovoids were found; however, no cracks were observed in the films that were investigated by TEM.
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growth of gallium nitride by hydride Vapor Phase Epitaxy
Journal of Crystal Growth, 1997Co-Authors: R J Molnar, W Gotz, Linda T Romano, N M JohnsonAbstract:Abstract This paper reviews the growth of GaN thick films by hydride Vapor-Phase Epitaxy (HVPE). Emphasis is placed on recent developments, including the growth of nondegenerate material, characterization of film properties and suitability of such films for epitaxial device overgrowths. Films up to 74 μm thick have been deposited on sapphire substrates with no evidence of thermally induced cracking and a room-temperature Hall mobility of 880 cm 2 /V s at 293 K. Dislocation densities have been found to decrease with film thickness to 5 × 10 7 cm −2 for a 40 μm thick sample. Epitaxial films overgrown on these HVPE GaN buffers, both by organometallic Vapor-Phase Epitaxy and molecular-beam Epitaxy, replicate the defect structure of the HVPE buffer, resulting in dislocation densities no higher than the HVPE buffer and lower than are typically observed for nitride epilayers grown on other substrate materials. Efforts towards film/substrate separation will be discussed.
John Simon - One of the best experts on this subject based on the ideXlab platform.
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gallium arsenide solar cells grown at rates exceeding 300 µm h 1 by hydride Vapor Phase Epitaxy
Nature Communications, 2019Co-Authors: Wondwosen Metaferia, Kevin L Schulte, John Simon, Steve Johnston, Aaron J PtakAbstract:We report gallium arsenide (GaAs) growth rates exceeding 300 µm h−1 using dynamic hydride Vapor Phase Epitaxy. We achieved these rates by maximizing the gallium to gallium monochloride conversion efficiency, and by utilizing a mass-transport-limited growth regime with fast kinetics. We also demonstrate gallium indium phosphide growth at rates exceeding 200 µm h−1 using similar growth conditions. We grew GaAs solar cell devices by incorporating the high growth rate of GaAs and evaluated its material quality at these high rates. Solar cell growth rates ranged from 35 to 309 µm h−1 with open circuit voltages ranging from 1.04 to 1.07 V. The best devices exceeded 25% efficiency under the AM1.5 G solar spectrum. The high open-circuit voltages indicate that high material quality can be maintained at these extremely high growth rates. These results have strong implications toward lowering the deposition cost of III-V materials potentially enabling the deposition of high efficiency devices in mere seconds. Gallium arsenide holds record efficiency for single junction solar cells, but high production costs limit applications. Here Metaferia et al. show high quality GaAs and GaInP at rates exceeding 300 and 200 micrometers per hour by dynamic hydride Vapor Phase Epitaxy and > 25% efficient solar cells.
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iii v based optoelectronics with low cost dynamic hydride Vapor Phase Epitaxy
Crystals, 2018Co-Authors: John Simon, Kevin L Schulte, Kelsey A W Horowitz, Timothy Remo, David L Young, Aaron J PtakAbstract:Silicon is the dominant semiconductor in many semiconductor device applications for a variety of reasons, including both performance and cost. III-V materials exhibit improved performance compared to silicon, but currently, they are relegated to applications in high-value or niche markets, due to the absence of a low-cost, high-quality production technique. Here we present an advance in III-V materials synthesis, using a hydride Vapor Phase Epitaxy process that has the potential to lower III-V semiconductor deposition costs, while maintaining the requisite optoelectronic material quality that enables III-V-based technologies to outperform Si. We demonstrate the impacts of this advance by addressing the use of III-Vs in terrestrial photovoltaics, a highly cost-constrained market.
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Upright and Inverted Single-Junction GaAs Solar Cells Grown by Hydride Vapor Phase Epitaxy
IEEE Journal of Photovoltaics, 2017Co-Authors: John Simon, Kevin L Schulte, Steve Johnston, David L Young, Nikhil Jain, Michelle Young, Matthew R. Young, Aaron J PtakAbstract:Hydride Vapor Phase Epitaxy (HVPE) is a low-cost alternative to conventional metal-organic Vapor Phase Epitaxy (MOVPE) growth of III-V solar cells. In this work, we show continued improvement of the performance of HVPE-grown single-junction GaAs solar cells. We show over an order of magnitude improvement in the interface recombination velocity between GaAs and GaInP layers through the elimination of growth interrupts, leading to increased short-circuit current density and open-circuit voltage compared with cells with interrupts. One-sun conversion efficiencies as high as 20.6% were achieved with this improved growth process. Solar cells grown in an inverted configuration that were removed from the substrate showed nearly identical performance to on-wafer cells, demonstrating the viability of HVPE to be used together with conventional wafer reuse techniques for further cost reduction. These devices utilized multiple heterointerfaces, showing the potential of HVPE for the growth of complex and high-quality III-V devices.
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GaAs Solar Cells Grown by Hydride Vapor-Phase Epitaxy and the Development of GaInP Cladding Layers
IEEE Journal of Photovoltaics, 2016Co-Authors: John Simon, Kevin L Schulte, David L Young, Nancy M. Haegel, Aaron J PtakAbstract:The high cost of high-efficiency III-V photovoltaic devices currently limits them to niche markets. Hydride Vapor-Phase Epitaxy (HVPE) growth of III-V materials recently reemerged as a low-cost, high-throughput alternative to conventional metal- organic Vapor-Phase Epitaxy (MOVPE) growth of high-efficiency solar cells. Previously, we demonstrated unpassivated HVPEgrown GaAs p-n junctions with good quantum efficiency and high open-circuit voltage (Voc). In this work, we demonstrate the growth of GaInPby HVPE for use as a high-quality surface passivation layer to GaAs solar cells. Solar cells grown with GaInP window layers show significantly improved quantum efficiency compared with unpassivated cells, increasing the short-circuit current (JSC ) of these low-cost devices. These results show the potential of low-cost HVPE for the growth of high-quality III-V devices.
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low cost iii v solar cells grown by hydride Vapor Phase Epitaxy
Photovoltaic Specialists Conference, 2014Co-Authors: John Simon, David L Young, Aaron J PtakAbstract:The high epitaxial cost of high-efficiency III–V photovoltaic devices has limited these cells to niche markets. In this work, we demonstrate hydride Vapor-Phase Epitaxy (HVPE) growth of III–V materials as a low-cost, high-throughput alternative to conventional metal-organic Vapor-Phase Epitaxy (MOVPE). A brand new, custom-built HVPE reactor was used to obtain high-quality GaAs films at growth rates as high as 1.5 µm/min (90 µm/h). Near-ideal Hall mobilities for both n- and p-type carriers are demonstrated. Preliminary GaAs p-n junctions with unpassivated surfaces show significant rectifying behavior and excellent carrier collection, open-circuit voltage as high as 0.95 V, and fill factors of 86% under AM1.5G illumination. These results show the viability of HVPE for the growth of high-quality III–V devices at significantly lower costs.
Laurent Diehl - One of the best experts on this subject based on the ideXlab platform.
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high temperature continuous wave operation of strain balanced quantum cascade lasers grown by metal organic Vapor Phase Epitaxy
Applied Physics Letters, 2006Co-Authors: Laurent Diehl, David P Bour, Scott W Corzine, Mariano Troccoli, Jintian Zhu, Gloria E Hofler, M Loncar, Federico CapassoAbstract:The authors report the fabrication of high-power strained quantum cascade lasers working in continuous mode above 370K. The devices, processed in narrow buried heterostructures, were grown by low-pressure metal organic Vapor-Phase Epitaxy. Continuous wave output power as high as 312mW at 300K was obtained at a wavelength of 5.29μm from a 3.25mm long, 7.5μm wide laser with a high-reflectivity back facet coating. The slope efficiency was in excess of 1.5W∕A and the power conversion efficiency reached almost 5%.
-
pulsed and continuous mode operation at high temperature of strained quantum cascade lasers grown by metalorganic Vapor Phase Epitaxy
Applied Physics Letters, 2006Co-Authors: Laurent Diehl, David P Bour, Scott W Corzine, G Hofler, C Y Wang, Mariano Troccoli, Federico CapassoAbstract:We present the pulsed operation at room temperature of different strained InGaAs∕AlInAs quantum-cascade lasers grown by low-pressure metalorganic Vapor-Phase Epitaxy. Devices based on a bound-to-continuum transition design have threshold current densities in pulsed mode as low as 1.84kA∕cm2 at 300K. Identical lasers grown at higher rate (0.5nm∕s) also have threshold current densities lower than 2kA∕cm2 at 300K. Buried heterostructure lasers based on a double phonon resonance design were operated in continuous mode up to 280K. Overall, the performance obtained from strained quantum cascade lasers deposited by metalorganic Vapor-Phase Epitaxy are comparable with that of similar structures grown by molecular beam Epitaxy.
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low threshold continuous wave operation of quantum cascade lasers grown by metalorganic Vapor Phase Epitaxy
Applied Physics Letters, 2004Co-Authors: Mariano Troccoli, Laurent Diehl, David P Bour, Scott W Corzine, G Hofler, Ashish Tandon, D E Mars, David J Smith, Federico CapassoAbstract:We report on the realization of InGaAs∕InAlAs quantum-cascade lasers grown by metalorganic Vapor Phase Epitaxy operating in continuous wave with low-threshold current densities at temperatures as high as 188K. Threshold current densities of 950A∕cm2 and output powers of 125mW are measured at 80K, while 3mW of continuous output power are measured at 180K, with a threshold of 2.5kA∕cm2. In pulsed mode, peak output powers of more than 0.4W were obtained at 80K and of 160mW at 300K with thresholds of 700A∕cm2 and 2.75kA∕cm2, respectively.
