First-principles investigation of phase transition from zincblende to L10 at high temperature in Si0.5Sn0.5 alloys

Silicon tin (Si1-xSnx) alloy with a Sn composition of nearly 50% is promising in indirect-to-direct transition by the introduction of Sn atoms into silicon crystals. Theoretical calculations of the thermal stability were performed for each of the five unique crystal structures in Si0.5Sn0.5, including the zincblende. The results show a phase transition from zincblende to L-10 structure at 1020 K. The energy bandgap narrows from 1.05 eV to 0.75 eV at 450 K and to 0.54 eV at higher temperatures. It suggests that annealing above 450 K should be avoided for near-infrared light emission.