First-principles calculations on the electronic structure and optical properties of Mg2Si epitaxial on Si (111)

The electronic structure and optical properties of Mg2Si for the epitaxial relationship Mg2Si (111)//Si (111) are calculated by using the first-principles pseudopotential method based on the density functional theory. The results show that Mg2Si is the most steady state when the lattice parameter a of the primitive cell is 0.4522 nm; Mg2Si is an indirect semiconductor with the band gap of 0.2261 eV; the valence bands of Mg2Si near the Fermi surface are composed of Si 3p, Mg 3s, 3p and the conduction bands are mainly composed of Mg 3s, 3p as well as Si 3p; the static dielectric function is 18.7369.