Effect of strain relaxation on forward bias dark currents in GaAs/InGaAs multiquantum well p–i–n diodes

a b s t r a c tA series of GaAsBi/GaAs multiple quantum well p-i-n diodes were grown by molecular beam epitaxy. Nomarski images showed evidence of sub-surface damage in each diode, with an increase in the crosshatching associated with strain relaxation for the diodes containing more than 40 quantum wells. X-ray diffraction ω-2θ scans of the (004) reflections showed that multiple quantum well regions with clearly defined well periodicities were grown. The superlattice peaks of the diodes containing more than 40 wells were much broader than those of the other diodes. The photoluminescence spectra showed a redshift of 56 meV and an attenuation of nearly two orders of magnitude for the 54 and 63 well diodes. Calculations of the quantum confinement and strain induced band gap modifications suggest that the wells in all diodes are thinner than their intended widths and that both loss of quantum confinement and strain probably contributed to the observed redshift and attenuation in the 54 and 63 well diodes. Comparison of this data with that gathered for InGaAs/GaAs multiple quantum wells, suggests that the onset of relaxation occurs at a similar average strain-thickness product for both systems. Given the rapid band gap reduction of GaAsBi with Bi incorporation, this data suggests that GaAsBi is a promising photovoltaic material candidate.

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“…The results from this work are compared to those of Griffin et al [13] from the InGaAs/GaAs material system in Fig. 6.…”

Section: Comparison With Ingaas/gaasmentioning

confidence: 91%

“…Even so, this data suggests that GaAsBi could be a suitable alternative to InGaAs for PV applications The calculations were performed using the method of Ref. [13]. The error bars were estimated from the range of Bi contents that produced a reasonable fit between the measured and modelled XRD scans.…”

Section: Comparison With Ingaas/gaasmentioning

confidence: 99%

MBE grown GaAsBi/GaAs multiple quantum well structures: Structural and optical characterization

Richards

Bastiman

Roberts

et al. 2015

Journal of Crystal Growth

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“…This is why strain-balancing was shown before long to be a critical issue in developing efficient solar cells involving nanostructures such as quantum wells 10, 11 . Therefore, materials lattice-matched to GaAs/Ge and with a 1.0 eV or 1.15 eV bandgap are being extensively investigated.…”

Section: Introductionmentioning

confidence: 99%

Strain-balanced type-II superlattices for efficient multi-junction solar cells

Gonzalo

Utrilla

Reyes

et al. 2017

Sci Rep

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Multi-junction solar cells made by assembling semiconductor materials with different bandgap energies have hold the record conversion efficiencies for many years and are currently approaching 50%. Theoretical efficiency limits make use of optimum designs with the right lattice constant-bandgap energy combination, which requires a 1.0–1.15 eV material lattice-matched to GaAs/Ge. Nevertheless, the lack of suitable semiconductor materials is hindering the achievement of the predicted efficiencies, since the only candidates were up to now complex quaternary and quinary alloys with inherent epitaxial growth problems that degrade carrier dynamics. Here we show how the use of strain-balanced GaAsSb/GaAsN superlattices might solve this problem. We demonstrate that the spatial separation of Sb and N atoms avoids the ubiquitous growth problems and improves crystal quality. Moreover, these new structures allow for additional control of the effective bandgap through the period thickness and provide a type-II band alignment with long carrier lifetimes. All this leads to a strong enhancement of the external quantum efficiency under photovoltaic conditions with respect to bulk layers of equivalent thickness. Our results show that GaAsSb/GaAsN superlattices with short periods are the ideal (pseudo)material to be integrated in new GaAs/Ge-based multi-junction solar cells that could approach the theoretical efficiency limit.

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“…В силу эффективной релаксации упругих напряжений вертикальное складирование большого числа рядов КТ может быть реализовано без возникновения дислока-ций. Квантовые ямы обладают значительно большим оптическим усилением/поглощением по сравнению с КТ, однако вследствие накопления упругих напряжений возможности их складирования ограничены [9].…”

Section: Introductionunclassified

Бимодальность в массивах гибридных квантово-размерных гетероструктур In-=SUB=-0.4-=/SUB=-Ga-=SUB=-0.6-=/SUB=-As, выращенных на подложках GaAs

Надточий¹,

Mintairov²,

Калюжный³

et al. 2018

Физика И Техника Полупроводников

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Hybrid quantum-confined heterostructures grown by metal-organic vapor-phase epitaxy (MOVPE) via the deposition of In_0.4Ga_0.6As layers with various nominal thicknesses onto vicinal GaAs substrates are studied by photoluminescence spectroscopy and transmission electron microscopy. The photoluminescence spectra of these structures show the superposition of two spectral lines, which is indicative of the bimodal distribution of the size and/or shape of light-emitting objects in an array. The dominant spectral line is attributed to the luminescence of hybrid “quantum well–dot” nanostructures in the form of a dense array of relatively small quantum dots (QDs) with weak electron and hole localization. The second, lower intensity line is attributed to luminescence from a less dense array of comparatively larger QDs. Analysis of the behavior of the spectral line intensities at various temperatures showed that the density of larger QDs grows with increasing thickness of the InGaAs layer.

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Effect of strain relaxation on forward bias dark currents in GaAs/InGaAs multiquantum well p–i–n diodes

Cited by 45 publications

References 15 publications

MBE grown GaAsBi/GaAs multiple quantum well structures: Structural and optical characterization

MBE grown GaAsBi/GaAs multiple quantum well structures: Structural and optical characterization

Strain-balanced type-II superlattices for efficient multi-junction solar cells

Бимодальность в массивах гибридных квантово-размерных гетероструктур In-=SUB=-0.4-=/SUB=-Ga-=SUB=-0.6-=/SUB=-As, выращенных на подложках GaAs

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