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Strain-Driven Dewetting and Interdiffusion in SiGe Thin Films on SOI for CMOS-Compatible Nanostructures

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Published in:Nanomaterials vol. 15, no. 13 (2025), p. 965-979
Main Author: Freddi Sonia
Other Authors: Gherardi, Michele, Chiappini, Andrea, Adam, Arette-Hourquet, Berbezier Isabelle, Fedorov Alexey, Chrastina, Daniel, Bollani, Monica
Published:
MDPI AG
Subjects:
Silicon
Nucleation
Energy dispersive X ray spectroscopy
Scanning electron microscopy
Investigations
Strain relaxation
Drying
Molecular beam epitaxy
X-ray diffraction
Silicon substrates
Atomic force microscopy
Raman spectroscopy
Thin films
Annealing
Epitaxial growth
Germanium
Spectrum analysis
Silicon germanides
Interdiffusion
Nanostructure
Lasers
Temperature
Concentration gradient
Etching
CMOS
Nanocrystals
SOI (semiconductors)
Quantum dots
X-ray spectroscopy
Microscopy
Morphology
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Abstract:This study provides new insight into the mechanisms governing solid state dewetting (SSD) in SiGe alloys and underscores the potential of this bottom-up technique for fabricating self-organized defect-free nanostructures for CMOS-compatible photonic and nanoimprint applications. In particular, we investigate the SSD of Si1−xGex thin films grown by molecular beam epitaxy on silicon-on-insulator (SOI) substrates, focusing on and clarifying the interplay of dewetting dynamics, strain elastic relaxation, and SiGe/SOI interdiffusion. Samples were annealed at 820 °C, and their morphological and compositional evolution was tracked using atomic force microscopy (AFM), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), and Raman spectroscopy, considering different annealing time steps. A sequential process typical of the SiGe alloy has been identified, involving void nucleation, short finger formation, and ruptures of the fingers to form nanoislands. XRD and Raman data reveal strain relaxation and significant Si-Ge interdiffusion over time, with the Ge content decreasing from 29% to 20% due to mixing with the underlying SOI layer. EDX mapping confirms a Ge concentration gradient within the islands, with higher Ge content near the top.
ISSN:2079-4991
DOI:10.3390/nano15130965
Source:Materials Science Database