We evaluated the potential of polycrystalline (poly-) GeSn as channel material for the fabrication of thin film transistors (TFTs) at a low thermal budget (<600 degrees C). Poly-GeSn films with a grain size of similar to 50 nm showed a carrier mobility of similar to 30 cm(2) V-1 s(-1) after low-temperature annealing at 475-500 degrees C. Not only carrier mobility but also thermal conductivity of the films is important in assessing the self-heating effect of the poly-GeSn channel TFT. The thermal conductivity of the poly-GeSn films is 5-9 W m(-1) K-1, which is significantly lower compared with 30-60 W m(-1) K-1 of bulk Ge; this difference results from phonon scattering at grain boundaries and Sn interstitials. The poly-GeSn films have higher carrier mobility and thermal conductivity than poly-Ge films annealed at 600 degrees C, because of the improved crystal quality and coarsened grain size resulting from Sn-induced crystallization. Therefore, the poly-GeSn film is well-suited as channel material for TFTs, fabricated with a low thermal budget. (C) 2015 AIP Publishing LLC.