MODELING OF STRUCTURAL PROPERTIESOF Ge1–xSnx ALLOYS  

Vasin Aleksandr Sergeevich, Candidate of physical and mathematical sciences, associate professor, sub-department of information technologies in physical research, Lobachevsky State University of Nizhny Novgorod (23 Gagarina avenue, Nizhny Novgorod, Russia), vasin@phys.unn.ru

538.91:548.31

10.21685/2072-3040-2016-4-9

Background. The literature indicates the possibility of creating interesting optoelectronic devices on the basis of semiconductor solid solutions of elements of group IV of the periodic system with the prospect of integration into silicon technology. The Ge1-xSnx alloy seems to be the most promising for this purpose and is intensively studied experimentally and theoretically. The aim of this work is to model the alloy’s structural properties: restructuring of the crystal lattice, lengths of atomic bonds, angles between bonds depending on the composition.
Materials and methods. The author investigated a Ge1–xSnx solid solution both for the practically important range of tin fraction 0 < x < 0,2, and for any theoretically interesting value of x. There was simulated a cluster of about 4 thousand atoms, which was investigated by molecular dynamics (MD) using the Tersoff potential.  
Results. The researcher has obtained dependences of lattice parameters, bond lengths, angles between bonds on the composition, as well as compared with experimental and calculated (ab initio) results. There has been discovered a deviation from the Vegard law, as well as significantly different contributions of Ge-Ge, Ge-Sn, SnSn bonds in the lattice distortion when changing the composition of the alloy.
Conclusions. The obtained results can be used in evaluation of the elastic-stress state of GeSn films grown on various substrates. The study of the Ge1–xSnx alloy by the MD method allows to conduct researches on much larger clusters than by quantum-mechanical calculations and to obtain comparable results.

solid solutions, germanium–tin alloy, molecular dynamics method, Tersoff potential

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