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RHEED investigation of the self-assembly of InAs quantum dots on AlGaAs.

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Title: RHEED investigation of the self-assembly of InAs quantum dots on AlGaAs.
Authors: Espinosa-Vega, L.I.1 (AUTHOR), Yépez-Barradas, G.1 (AUTHOR), Cortés-Mestizo, I.E1,2 (AUTHOR), Vilchis, Daniel1 (AUTHOR), Mora-Herrera, M.F.1 (AUTHOR), Vázquez-Cortés, David3 (AUTHOR), LaGrow, Alec P.3 (AUTHOR), Cuellar-Camacho, J.L.2,4 (AUTHOR), Ruíz-García, J.5 (AUTHOR), Méndez-García, Víctor H.1 (AUTHOR) victor.mendez@uaslp.mx
Source: Journal of Crystal Growth. Sep2026, Vol. 690, pN.PAG-N.PAG. 1p.
Subjects: Reflection high energy electron diffraction, Nucleation, Nanofabrication, Quantum dots, Diffusion kinetics, Ternary alloys, Molecular beam epitaxy
Abstract: • Critical thickness remains nearly constant across Al x Ga 1−x As. • Weak dependence of nucleation onset challenges classical models. • Nucleation shifts toward diffusion-limited regime with Al content. • QD density and morphology correlate with nucleation dynamics. • Decoupled roles of strain and kinetics govern QD formation. The growth of InAs QDs on Al x Ga 1−x As layers with systematically varied Al molar fraction using molecular beam epitaxy is investigated. The growth process is monitored in situ by reflection high-energy electron diffraction (RHEED), enabling a detailed analysis of the nucleation dynamics, the critical thickness for the two-dimensional to three-dimensional (2D–3D) transition, and diffusion-related kinetic parameters within a single stacked heterostructure. Contrary to previously reported investigations performed on single heterostructures, the critical thickness of InAs on AlGaAs is found to remain nearly constant for intermediate Al content, exhibiting only minor variations, while a modest increase is observed in the AlAs limit (x = 1). Diffusion-related parameters extracted from the RHEED intensity evolution display a slight but clear dependence on the aluminum composition, indicating a progressive transition toward diffusion-limited growth. These kinetic effects are further correlated with changes in the initial surface roughness. It is also found that surface diffusion during growth, which presumably varies with Al content, has direct consequences on the pyramidal shape of the nano islands. [ABSTRACT FROM AUTHOR]
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Database: Engineering Source
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Abstract:• Critical thickness remains nearly constant across Al x Ga 1−x As. • Weak dependence of nucleation onset challenges classical models. • Nucleation shifts toward diffusion-limited regime with Al content. • QD density and morphology correlate with nucleation dynamics. • Decoupled roles of strain and kinetics govern QD formation. The growth of InAs QDs on Al x Ga 1−x As layers with systematically varied Al molar fraction using molecular beam epitaxy is investigated. The growth process is monitored in situ by reflection high-energy electron diffraction (RHEED), enabling a detailed analysis of the nucleation dynamics, the critical thickness for the two-dimensional to three-dimensional (2D–3D) transition, and diffusion-related kinetic parameters within a single stacked heterostructure. Contrary to previously reported investigations performed on single heterostructures, the critical thickness of InAs on AlGaAs is found to remain nearly constant for intermediate Al content, exhibiting only minor variations, while a modest increase is observed in the AlAs limit (x = 1). Diffusion-related parameters extracted from the RHEED intensity evolution display a slight but clear dependence on the aluminum composition, indicating a progressive transition toward diffusion-limited growth. These kinetic effects are further correlated with changes in the initial surface roughness. It is also found that surface diffusion during growth, which presumably varies with Al content, has direct consequences on the pyramidal shape of the nano islands. [ABSTRACT FROM AUTHOR]
ISSN:00220248
DOI:10.1016/j.jcrysgro.2026.128639