This project is aimed at systematically probe how the local atomic structure and chemical order at the atomic scale is related to the optical and thermal properties of SiGeSn thin films. Here we propose to carry out Sn-K edge EXAFS data on SiGeSn thin films deposited on Ge/Si relaxed substrates by means of CVD or MBE. The deposition parameters will be modified in order to relate the Sn local atomic structure to the optical and thermal properties of the films.