Document Detail

Direct Measurement of Coherency Limits for Strain Relaxation in Heteroepitaxial Core/Shell Nanowires.
MedLine Citation:
PMID:  23030346     Owner:  NLM     Status:  Publisher    
The growth of heteroepitaxially-strained semiconductors at the nanoscale enables tailoring of material properties for improved device performance. For core/shell nanowires (NWs), theoretical predictions of the coherency limits and the implications they carry remain uncertain without proper identification of the mechanisms by which strains relax. We present here for the Ge/Si core/shell NW system the first experimental measurement of critical shell thickness for strain relaxation in a semiconductor NW heterostructure and identification of the relaxation mechanisms. Axial and tangential strain relief is initiated by the formation of periodic a/2<110> perfect dislocations via nucleation and glide on {111} slip-planes. Glide of dislocation segments is directly confirmed by real-time in-situ transmission electron microscope observations and by Dislocation Dynamics simulations. Additional shell growth leads to roughening and grain formation which provides additional strain relief. As a consequence of core/shell strain sharing in NWs, a 16 nm radius Ge NW with a 3 nm Si shell is shown to accommodate 3 % coherent strain at equilibrium, a factor of 3 increase over the 1 nm equilibrium critical thickness for planar Si/Ge heteroepitaxial growth.
Shadi Ahmad Dayeh; Wei Tang; Francesca Boiolo; Karen L Kavanagh; He Zheng; Jian Wang; Nathan H Mack; John Greg Swadener; Jian Yu Huang; Leo Miglio; King-Ning Tu; S Tom Picraux
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Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2012-10-3
Journal Detail:
Title:  Nano letters     Volume:  -     ISSN:  1530-6992     ISO Abbreviation:  Nano Lett.     Publication Date:  2012 Oct 
Date Detail:
Created Date:  2012-10-3     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  101088070     Medline TA:  Nano Lett     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
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