Photovoltaic characterisation of GaAsBi/GaAs multiple quantum well devices

Richards, Robert D.; Mellor, A.; Harun, Faezah; Cheong, Jeng Shiuh; Hylton, Nicholas P.; Wilson, Terence; Thomas, Tomos; Roberts, J.S.; Ekins-Daukes, N. J.; David, J.P.R.

doi:10.1016/j.solmat.2017.07.029

Cited by 43 publications

(33 citation statements)

References 43 publications

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“…1,2 However, due to the large mismatch in atomic size and electronegativity between arsenic (As) and Bi, the bulk solubility limit of Bi in GaAs is extremely low (x < 5.2 9 10 À5 ), 3 requiring nonequilibrium growth techniques to access these unique bandgap/lattice constant combinations. Techniques such as molecular beam epitaxy (MBE) and metalorganic vaporphase epitaxy (MOVPE) are well suited for this purpose and have led to bismide devices with x = 0.02 to 0.074 Bi fraction, as demonstrated in photodiodes [4][5][6] and near-infrared (IR) lasers. 7 Additionally, there is great interest in incorporating higher-bismuth-fraction (x > 0.10) materials into devices to reduce Auger recombination in mid-IR lasers 8 and increase diode efficiency in thermophotovoltaic power systems.…”

Section: Introductionmentioning

confidence: 99%

Impact of Rotation Rate on Bismuth Saturation in GaAsBi Grown by Molecular Beam Epitaxy

Stevens

Grossklaus

McElearney

et al. 2019

Journal of Elec Materi

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GaAs 1Àx Bi x has been grown by solid-source molecular beam epitaxy using varying substrate rotation rates. Changes in local bismuth saturation were studied by varying the Bi/Ga pressure ratio across the wafer. Films were grown on both GaAs and InGaAs buffer layers with varying indium content to change the strain conditions of the bismide layer and the out-of-plane growth rate. All samples demonstrated vertical composition modulations with a period of $ 4 nm that tracked with the rate of growth per substrate rotation cycle. The thermal stability of these composition modulations was shown to behave similarly to bulk GaAsBi. Bismide composition modulations are attributed to the low growth temperature and the varying Bi/Ga pressure ratio across the sample rather than the varying V/III ratio.

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Section: Introductionmentioning

confidence: 99%

Impact of Rotation Rate on Bismuth Saturation in GaAsBi Grown by Molecular Beam Epitaxy

Stevens

Grossklaus

McElearney

et al. 2019

Journal of Elec Materi

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“…The incorporation of dilute quatities of bismuth into GaAs has been highlighted as a promising material system for a range of optoelectronic device applications, including telecommunications band (1550–1300 nm) lasers 1–3 , mid-IR photosensitive detectors 4–7 and multi-junction photovoltaics (PV) 8–10 . The application of dilute bismide alloys to multi-junction PV could offer a suitable pathway to realising a highly desirable 1.0 eV band-gap sub-cell, which is crucial for the development of future four junction solar cells.…”

Section: Introductionmentioning

confidence: 99%

Assessing the Nature of the Distribution of Localised States in Bulk GaAsBi

Wilson

Hylton

Harada

et al. 2018

Sci Rep

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A comprehensive assessment of the nature of the distribution of sub band-gap energy states in bulk GaAsBi is presented using power and temperature dependent photoluminescence spectroscopy. The observation of a characteristic red-blue-red shift in the peak luminescence energy indicates the presence of short-range alloy disorder in the material. A decrease in the carrier localisation energy demonstrates the strong excitation power dependence of localised state behaviour and is attributed to the filling of energy states furthest from the valence band edge. Analysis of the photoluminescence lineshape at low temperature presents strong evidence for a Gaussian distribution of localised states that extends from the valence band edge. Furthermore, a rate model is employed to understand the non-uniform thermal quenching of the photoluminescence and indicates the presence of two Gaussian-like distributions making up the density of localised states. These components are attributed to the presence of microscopic fluctuations in Bi content, due to short-range alloy disorder across the GaAsBi layer, and the formation of Bi related point defects, resulting from low temperature growth.

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“…This may allow suppressing the inter-valence band absorption and Auger-Meitner recombination in GaAs 1−x Bi x with concentrations x > 10% [4]. Combined with the reduced band gap sensitivity, these properties make the bismide an attractive candidate for applications in the long-wave infrared lasers, photodetectors, and multijunction solar cells, among others [1,[5][6][7].…”

Section: Introductionmentioning

confidence: 99%

Atomic-Resolution EDX, HAADF, and EELS Study of GaAs1-xBix Alloys

et al. 2020

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The distribution of alloyed atoms in semiconductors often deviates from a random distribution which can have significant effects on the properties of the materials. In this study, scanning transmission electron microscopy techniques are employed to analyze the distribution of Bi in several distinctly MBE grown GaAs 1−x Bi x alloys. Statistical quantification of atomic-resolution HAADF images, as well as numerical simulations, are employed to interpret the contrast from Bi-containing columns at atomically abrupt (001) GaAs-GaAsBi interface and the onset of CuPt-type ordering. Using monochromated EELS mapping, bulk plasmon energy red-shifts are examined in a sample exhibiting phase-separated domains. This suggests a simple method to investigate local GaAsBi unit-cell volume expansions and to complement standard X-ray-based lattice-strain measurements. Also, a single-variant CuPt-ordered GaAsBi sample grown on an offcut substrate is characterized with atomic scale compositional EDX mappings, and the order parameter is estimated. Finally, a GaAsBi alloy with a vertical Bi composition modulation is synthesized using a low substrate rotation rate. Atomically, resolved EDX and HAADF imaging shows that the usual CuPt-type ordering is further modulated along the [001] growth axis with a period of three lattice constants. These distinct GaAsBi samples exemplify the variety of Bi distributions that can be achieved in this alloy, shedding light on the incorporation mechanisms of Bi atoms and ways to further develop Bi-containing III-V semiconductors.

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Photovoltaic characterisation of GaAsBi/GaAs multiple quantum well devices

Cited by 43 publications

References 43 publications

Impact of Rotation Rate on Bismuth Saturation in GaAsBi Grown by Molecular Beam Epitaxy

Impact of Rotation Rate on Bismuth Saturation in GaAsBi Grown by Molecular Beam Epitaxy

Assessing the Nature of the Distribution of Localised States in Bulk GaAsBi

Atomic-Resolution EDX, HAADF, and EELS Study of GaAs1-xBix Alloys

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