Bandgap and optical absorption edge of GaAs1−xBix alloys with 0 &amp;lt; x &amp;lt; 17.8%

Masnadi-Shirazi, Mostafa; Lewis, Ryan B.; Bahrami-Yekta, Vahid; Tiedje, T.; Chicoine, M.; Servati, Peyman

doi:10.1063/1.4904081

Cited by 58 publications

(43 citation statements)

References 37 publications

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“…15 Such structures offer the potential to realize GaAs-based optoelectronics operating at longer wavelengths than those possible with conventional alloying elements such as In and Sb, owing to the large reduction of the GaAs band gap obtained by Bi alloying. 16 In this work, we show that surfactant Bi can induce the formation of InAs 3D nanostructures directly on the {110} sidewalls of GaAs NWs. The surface Bi provokes the nucleation of 3D InAs islands at the corners of the {110} facets, while growth in the absence of Bi results in a 2D shell.…”

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confidence: 70%

Self-Assembly of InAs Nanostructures on the Sidewalls of GaAs Nanowires Directed by a Bi Surfactant

et al. 2017

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Surface energies play a dominant role in the self-assembly of three dimensional (3D) nanostructures. In this letter, we show that using surfactants to modify surface energies can provide a means to externally control nanostructure self-assembly, enabling the synthesis of novel hierarchical nanostructures. We explore Bi as a surfactant in the growth of InAs on the {110} sidewall facets of GaAs nanowires. The presence of surface Bi induces the formation of InAs 3D islands by a process resembling the StranskiKrastanov mechanism, which does not occur in the absence of Bi on these surfaces. The InAs 3D islands nucleate at the corners of the {110} facets above a critical shell thickness and then elongate along 110 directions in the plane of the nanowire sidewalls. Exploiting this growth mechanism, we realize a series of novel hierarchical nanostructures, ranging from InAs quantum dots on single {110} nanowire facets to zig-zag shaped nanorings completely encircling nanowire cores. Photoluminescence spectroscopy and cathodoluminescence spectral line scans reveal that small surfactant-induced InAs 3D islands behave as optically active quantum dots. This work illustrates how surfactants can provide an unprecedented level of external control over nanostructure self-assembly. KEYWORDS: nanowire, quantum dot, bismuth, surfactant, GaAs, semiconductor 2The bottom-up self-assembly of semiconductor nanostructures is directed by energy minimization. As a result, many aspects of nanostructure self-assembly are intrinsic and therefore difficult to control externally. For example, nanostructures such as nanowires (NWs) and quantum dots (QDs) spontaneously form low-energy facets during their synthesis. In the case of GaAs NWs grown by the Ga-assisted vapor-liquid-solid (VLS) mode, the sidewall facets are of {110} orientation. 1 This poses challenges for the realization of advanced hierarchical structures, such as QDs embedded within NWs, 2,3 since two-dimensional (2D) layer growth is always favored on GaAs{110} surfaces and three-dimensional (3D) islands do not form by the StranskiKrastanov (SK) mechanism. 2,4-6 The SK growth of InAs 3D islands on these surfaces has been observed after covering the facets with a thin AlAs layer, but, this is undesirable for most applications. 2,7 In contrast, GaAs NWs synthesized by Au-catalyzed growth typically exhibit {112} sidewall facets and the SK mechanism does occur on these surfaces, 6,8 however, the presence of Au can be detrimental to NW optoelectronic properties. 9 We recently reported that the presence of surface Bi can induce the self-assembly of InAs 3D islands directly on planar GaAs(110) surfaces. 10 The Bi surfactant was shown to modify the surface energies, reducing the energetic cost of 3D island formation. Furthermore, in contrast to more common surface-segregating elements like Sb and Te, which have been shown to reduce adatom diffusion and consequently inhibit the formation of 3D islands, 11,12 Bi has been found to increase adatom diffusion. 13 This makes Bi of particular i...

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confidence: 70%

Self-Assembly of InAs Nanostructures on the Sidewalls of GaAs Nanowires Directed by a Bi Surfactant

et al. 2017

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“…Here a GaBi and a GaAs indicate respectively the lattice constants for the GaBi (6.33 Å238) and GaAs (5.65 Å), while P represents the distortion coefficient. For the case of a psuedomorphic dilute GaAsBi film, we input the pure GaAs distortion coefficient via the elastic constants; P = C 11 /( C 11 + 2 C 12 ) = 0.527.…”

Section: Resultsmentioning

confidence: 99%

“…In most cases, experimental probes are far larger than the dimensions of the droplets/tracks on the surface (order of nm to μ m7891011171934), with measurements unavoidably recording an unresolved average of the entire probed area. While the removal of Bi surface droplets post growth (through selective wet chemical etching), and prior to characterisation, appears to rid the Bi metal, a number of experimental studies383940 have neglected to consider their lasting impact on the structural and optical properties of the epitaxial surface. This issue we investigate in the present study using electron microscopy techniques and micro-optical probes (lateral resolution ~1 μ m).…”

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Surface effects of vapour-liquid-solid driven Bi surface droplets formed during molecular-beam-epitaxy of GaAsBi

Steele

Lewis

Horvat

et al. 2016

Sci Rep

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Herein we investigate a (001)-oriented GaAs1−xBix/GaAs structure possessing Bi surface droplets capable of catalysing the formation of nanostructures during Bi-rich growth, through the vapour-liquid-solid mechanism. Specifically, self-aligned “nanotracks” are found to exist trailing the Bi droplets on the sample surface. Through cross-sectional high-resolution transmission electron microscopy the nanotracks are revealed to in fact be elevated above surface by the formation of a subsurface planar nanowire, a structure initiated mid-way through the molecular-beam-epitaxy growth and embedded into the epilayer, via epitaxial overgrowth. Electron microscopy studies also yield the morphological, structural, and chemical properties of the nanostructures. Through a combination of Bi determination methods the compositional profile of the film is shown to be graded and inhomogeneous. Furthermore, the coherent and pure zincblende phase property of the film is detailed. Optical characterisation of features on the sample surface is carried out using polarised micro-Raman and micro-photoluminescence spectroscopies. The important light producing properties of the surface nanostructures are investigated through pump intensity-dependent micro-PL measurements, whereby relatively large local inhomogeneities are revealed to exist on the epitaxial surface for important optical parameters. We conclude that such surface effects must be considered when designing and fabricating optical devices based on GaAsBi alloys.

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“…Bi compositions up to x = 7% have been achieved in GaBi x As 1−x using MOVPE [27], while the ability to further lower the growth temperature using MBE means that larger Bi compositions can typically be achieved. GaBi x As 1−x alloys have recently been grown with Bi compositions as high as x = 17.8% using MBE [28].…”

Section: Devicesmentioning

confidence: 99%

Theory of the Electronic and Optical Properties of Dilute Bismide Quantum Well Lasers

Broderick

Harnedy

O’Reilly

2015

IEEE J. Select. Topics Quantum Electron.

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We present a theoretical study of the gain characteristics of GaBixAs1−x/(Al)GaAs dilute bismide quantum well (QW) lasers. After providing a brief overview of the current state of development of dilute bismide alloys for semiconductor laser applications, we introduce the theoretical model we have developed for the description of the electronic and optical properties of dilute bismide QWs. Using a theoretical approach based on a 12-band k·p Hamiltonian we then undertake a detailed analysis of the electronic and optical properties of a series of ideal and real GaBixAs1−x/(Al)GaAs QW laser structures as a function of Bi composition x. We theoretically optimize the gain characteristics of an existing low x device by varying the Al composition in the barrier layers, which governs a trade-off between the electronic and optical confinement. The theoretical results are compared to temperature-dependent spontaneous emission measurements at low x, which reveals the presence of significant Bi-induced inhomogeneous broadening of the optical spectra. We also investigate the gain characteristics of GaBixAs1−x/(Al)GaAs QW lasers at higher values of x, including a QW designed to emit at 1.55 µm. Our theoretical results elucidate the impact of Bi incorporation on the electronic and optical properties of GaAsbased QW lasers, and reveal several general trends in the gain characteristics as a function of x. Overall, our analysis confirms that dilute bismide alloys are a promising candidate material system for the development of highly efficient, uncooled GaAsbased QW lasers operating at telecommunication wavelengths.

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Bandgap and optical absorption edge of GaAs1−xBix alloys with 0 < x < 17.8%

Cited by 58 publications

References 37 publications

Self-Assembly of InAs Nanostructures on the Sidewalls of GaAs Nanowires Directed by a Bi Surfactant

Self-Assembly of InAs Nanostructures on the Sidewalls of GaAs Nanowires Directed by a Bi Surfactant

Surface effects of vapour-liquid-solid driven Bi surface droplets formed during molecular-beam-epitaxy of GaAsBi

Theory of the Electronic and Optical Properties of Dilute Bismide Quantum Well Lasers

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