Surface electronic structure, relaxations and thermodynamic energies of (100), (110) and (111) surfaces of Mg2Si: A first-principles theoretical study

Interplay between structural changes, surface states and quantum confinement effects in semiconducting Mg2Si and Ca2Si thin films

“…For the sake of comparison, the surface energy of Mg 2 Si(110) was also calculated and it turned out to be higher than the surface energy of Mg 2 Si(111) (see Table 1), which is consistent with the results in ref. 18 and 19. Hence, we do not further investigate Mg 2 Si thin films other than the cubic Mg 2 Si(111).…”

“…In the case of the cubic Mg 2 Si(111) thin films we did not detect any electronic states in the extrema points associated with surface atoms, which is consistent with the results of ref. 18 (see Fig. 10(a) therein).…”

“…14 After that it was possible to grow thicker (50-400 nm) epitaxial Ca 2 Si(100) and Ca 2 Si(010) films by the molecular beam epitaxy method. 14 The up-to-date reported results of first-principles investigations of Mg 2 Si surfaces (in particular (100), ( 110) and (111) ones) [15][16][17][18][19] suggest that the Mg-terminated Mg 2 Si(111) surface possesses the smallest surface energy. 18,19 For the orthorhombic Ca 2 Si thin films there is only one study 20 where the surface energy and the appearance of surface states have been discussed for the (100), ( 010) and (001) slabs.…”

“…The comparison of the total energies of the orthorhombic and cubic Ca 2 Si slabs with thickness below 1.5 nm indicated a possibility to stabilize cubic Ca 2 Si(111) thin films. 6 However, previous theoretical studies 6,[15][16][17][18][19][20] did not focus on thickness-dependent properties (such as an influence of quantum confinement effects on the band-gap variation and changes in the band dispersion with thickness) of Mg 2 Si and Ca 2 Si thin films.…”