Issue |
Microsc. Microanal. Microstruct.
Volume 6, Number 5-6, October / December 1995
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Page(s) | 473 - 482 | |
DOI | https://doi.org/10.1051/mmm:1995138 |
DOI: 10.1051/mmm:1995138
Strain Relaxation of Si/Ge Multilayers Investigated by Transmission Electron Microscopy and High-Resolution X-Ray Diffractometry
Elvio Carlino1, Cinzia Giannini1, Leander Tapfer1, Kurt A. Mäder2 et Hans von Känel21 PASTIS-Centro Nazionale Ricerca e Sviluppo Materiali (PASTIS-CNRSM) S.S. 7 Appia km. 712, 72100 Brindisi, Italy
2 Laboratorium für Festkörperphysics, ETH-Zürich, CH-8093, Switzerland
Abstract
In this work we investigate the strain-relief mechanisms and the
formation of structural defects of Si/Ge multilayers grown by
molecular beam epitaxy on (100)- Si substrates. The investigated
specimens differ in number of periods, period thickness, and in
the Si/Ge layer thickness ratio. The structural analyses are
performed by transmission electron microscopy and
high-resolution X-ray diffraction. We found that a Si-Ge
interdiffusion induces a broadening of the nominal thickness of
the Ge layer, producing a
alloy as well as
a higher Ge
content in the last periods of the multilayer structure. Our
measurements suggest that the strain relaxation occurs in two
steps: i) in each period of the multilayer the strain energy
density is partially reduced by the formation of coherent
islands; ii) at a certain value of the strain energy density,
the shape of the coherent islands changes and the structures,
partially or completely, relax the accumulated strain energy by
nucleation of dislocations. The increase of the strain energy
density is related to the measured monotonic increase of the Ge
content as a function of the growth time.
6865 - Low dimensional structures: growth, structure and nonelectronic properties.
6825 - Mechanical and acoustical properties of solid surfaces and interfaces.
6220F - Deformation and plasticity.
8140L - Deformation, plasticity and creep.
6822 - Surface diffusion, segregation and interfacial compound formation.
6170J - Etch pits, decoration, transmission electron microscopy and other direct observations of dislocations.
Key words
chemical interdiffusion -- deformation -- dislocation nucleation -- elemental semiconductors -- germanium -- semiconductor epitaxial layers -- semiconductor heterojunctions -- silicon -- transmission electron microscopy -- X ray diffraction -- multilayers -- high resolution X ray diffractometry -- TEM -- strain relief -- structural defects -- molecular beam epitaxy -- Si 100 substrates -- layer thickness ratio -- interdiffusion -- strain relaxation -- strain energy density -- coherent islands -- dislocation nucleation -- Ge content -- growth time -- semiconductors -- Si Ge -- SiGe -- Si
© EDP Sciences 1995