Low temperature reactions of thin layers of Mn with Si

Reactions between manganese thin films and silicon substrates, annealed at relatively low temperatures (<430 °C), have been systematically investigated. Three phases, i.e., Mn₃Si, Mn₅Si₃, and MnSi, were formed through a layered growth process. The formation sequence for these silicides was Mn₃Si, MnSi, and then Mn₅Si₃. The unusual phenomena of coexistence of these three phases and simultaneous growth of two phases (MnSi and Mn₅Si₃) were also observed. A model has been proposed to explain the growth behavior. The formation sequence of Mn₃Si, MnSi, and then Mn₅Si₃, and simultaneous growth of MnSi and Mn₅Si₃, can be explained by considering both thermodynamic and kinetic effects. Only those reactions that are thermodynamically allowed and kinetically preferred can take place. Kinetic preference is determined by the composition in the reaction region, which is controlled by the diffusion flux of the moving reactant. The proposed model is also compared with existing models.