TY  - JOUR
AU  - Corley-Wiciak, Agnieszka Anna
AU  - Ryzhak, Diana
AU  - Zoellner, Marvin Hartwig
AU  - Manganelli, Costanza Lucia
AU  - Concepción, Omar
AU  - Skibitzki, Oliver
AU  - Grützmacher, Detlev
AU  - Buca, Dan
AU  - Capellini, Giovanni
AU  - Spirito, Davide
TI  - Thermal expansion and temperature dependence of Raman modes in epitaxial layers of Ge and Ge 1 − x Sn x
JO  - Physical review materials
VL  - 8
IS  - 2
SN  - 2475-9953
CY  - College Park, MD
PB  - APS
M1  - FZJ-2024-01644
SP  - 023801
PY  - 2024
AB  - Temperature dependence of vibrational modes in semiconductors depends on lattice thermal expansion andanharmonic phonon-phonon scattering. Evaluating the two contributions from experimental data is not straightforward,especially for epitaxial layers that present mechanical deformation and anisotropic lattice expansion.In this paper, a temperature-dependent Raman study in epitaxial Ge and Ge1−xSnx layers is presented. A modelis introduced for the Raman mode energy shift as a function of temperature, comprising thermal expansion ofthe strained lattice and anharmonic corrections. With support of x-ray diffraction, the model is calibrated onexperimental data of epitaxial Ge grown on Si and Ge1−xSnx grown on Ge/Si, finding that the main differencebetween bulk and epitaxial layers is related to the anisotropic lattice expansion. The phonon anharmonicity andother parameters do not depend on dislocation defect density (in the range 7×106 – 4×108 cm−2) nor on alloycomposition in the range 5–14 at.%. The strain-shift coefficient for the main model of Ge and for the Ge-Gevibrational mode of Ge1−xSnx is weakly dependent on temperature and is around –500 cm–1. In Ge1−xSnx, thecomposition-shift coefficient amounts to –100 cm-1, independent of temperature and strain.
LB  - PUB:(DE-HGF)16
UR  - <Go to ISI:>//WOS:001156744300001
DO  - DOI:10.1103/PhysRevMaterials.8.023801
UR  - https://juser.fz-juelich.de/record/1023071
ER  -