Atomic-scale structural characterization of grain boundaries in epitaxial Ge/Si microcrystals by HAADF-STEM. (1st April 2019)

• Record Type: Journal Article
• Authors: Arroyo Rojas Dasilva, Yadira; Erni, Rolf; Isa, Fabio; Isella, Giovanni; von Känel, Hans; Gröning, Pierangelo; Rossell, Marta D.
• Is Part Of: Acta materialia. Volume 167(2019)
• Page Start: 159
• Page End: 166
• Publication Date: 2019-04-01
• Subjects: Grain boundaries -- Twin boundaries -- Triple junctions; Materials -- Periodicals; Materials science -- Periodicals; Materials -- Mechanical properties -- Periodicals; Metallurgy -- Periodicals; Chemistry, Inorganic -- Periodicals; 620.112
• DOI: 10.1016/j.actamat.2019.01.031
• Languages: English
• ISSNs: 1359-6454

Abstract

Abstract: The atomic structure of grain boundaries in Ge micro-crystals grown on Si pillars for the fabrication of a monolithically integrated X-ray detector was studied by high-resolution high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM). Three different boundaries are found in Ge: Σ 3 { 111 } coherent twin boundaries, Σ 3 { 112 } incoherent twin boundaries, and Σ 9 { 122 } and Σ 27 { 552 } grain boundaries. They are described using the structural unit models containing single columns. Remarkably, we find for the first time a Σ 3 { 112 } incoherent twin boundary exhibiting two different atomic structures; one symmetric and one asymmetric. Their co-occurrence is explained by the presence of a small step in the boundary plane and the introduction of dislocations. Likewise, the atomic structure of junctions formed by the interaction of twin boundaries which result in Σ 9 { 122 } and Σ 27 { 552 } grain boundaries is also revealed. Geometrical phase analysis is applied to map the strain fields at two triple junctions and to uncover the position of the dislocations. Graphical abstract: Image 1