The semi-conductor Ge 1x Sn x exhibits interesting properties for optoelectronic applications. In particular, Ge 1x Sn x alloys with x 0.1 exhibit a direct band-gap, and integrated in complementary-metal-oxide-semiconductor (CMOS) technology, should allow the development of Si photonics. CMOS-compatible magnetron sputtering deposition was shown to produce monocrystalline Ge 1x Sn x films with good electrical properties at low cost. However, these layers were grown at low temperature (< 430 K) and contained less than 6% of Sn. In this work, Ge 1x Sn x thin films were elaborated at higher temperature (> 600 K) on Si(001) by magnetron sputtering in order to produce low-cost and CMOS-compatible relaxed pseudocoherent layers with x ≥ 0.1 exhibiting a better crystallinity. Ge 1x Sn x crystallization and Ge 1x Sn x crystal growth were investigated. Crystallization of an amorphous Ge 1x Sn x layer deposited on Si(001) or Ge(001) grown on Si(001) leads to the growth of polycrystalline films. Furthermore, the competition between Ge/Sn phase separation and Ge 1x Sn x growth prevents the formation of large-grain Sn-rich Ge 1x Sn x layers without the formation of -Sn islands on the layer surface, due to significant atomic redistribution kinetics at the crystallization temperature (T = 733 K for x = 0.17). However, the growth at T = 633 K of a highly-relaxed pseudo-coherent Ge 0.9 Sn 0.1 film with low impurity concentrations (< 2 × 10 19 at cm 3 ) and an electrical resistivity four orders of 2 magnitude smaller than undoped Ge is demonstrated. Consequently, magnetron sputtering appears as an interesting technique for the integration of optoelectronic and photonic devices based on Ge 1x Sn x layers in the CMOS technology.