Ternary SiGeSn alloys have emerged as a promising material system for applications in diverse fields such as photonics, electronics, and thermoelectrics. Its development still requires understanding the alloy properties, where an important role is alleged to be the local arrangement of the Si, Ge, and Sn atoms. Structural properties of SiGeSn epitaxial layers deposited on Ge/Si virtual substrates are investigated here by polarized Raman spectroscopy; in particular, we selected a series of samples with Ge content of at.% and variable Si and Sn content. This technique, which provides access not only to the energy but also to the symmetry of the vibrational modes, makes it possible to observe the effect of composition on the local alloy ordering. By studying how the Raman modes change the energy and the relative intensity variation under different polarization configurations, we could isolate the role of alloy …