Thermal stability of Mg₂Si epitaxial film formed on Si(111) substrate by solid phase reaction

A single crystalline Mg₂Si film was formed by solid phase reaction (SPR) of a Si(111) substrate with an Mg overlayer capped with an oxide layer(s), which was enhanced by post annealing from room temperature to 100 ℃ in a molecular beam epitaxy (MBE) system. The thermal stability of the Mg₂Si film was then systematically investigated by post annealing in an oxygen-radical ambient at 300 ℃, 450 ℃ and 650 ℃, respectively. The Mg₂Si film stayed stable until the annealing temperature reached 450 ℃ then it transformed into amorphous MgO_x attributed to the decomposition of Mg₂Si and the oxidization of dissociated Mg.