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We present a synergic experimental and theoretical investigation of the plastic relaxation onset in low-temperature Ge growth on Si (001). High-resolution transmission electron microscopy reveals that misfit is released by pairs of coupled 60 dislocations. Atomic resolution proved to be key in distinguishing pairs from single 90 dislocations because of the revealed small intrapair dislocation distance (even less than 1 nm). By exploiting dislocation theory and molecular dynamics simulations, we demonstrate that the observed pairing naturally occurs as a result of the mutual interactions between the two dislocations. In particular, analytical models show that the stress field arising in a thin film when a dislocation segment lies at the interface with the substrate determines the most favored nucleation site for a new (complementary) dislocation that leads, after migration, to the coupling with the first in a stable position. At the …
American Physical Society
Publication date: 
18 Oct 2013

Anna Marzegalli, Matteo Brunetto, Marco Salvalaglio, Francesco Montalenti, Giuseppe Nicotra, Mario Scuderi, Corrado Spinella, Monica De Seta, Giovanni Capellini

Biblio References: 
Volume: 88 Issue: 16 Pages: 165418
Physical Review B