OPTICAL AND ELECTRONIC PROPERTIES OF M2Si (M = Mg, Ca, Sr) GROWN BY REACTIVE DEPOSITION TECHNIQUE

Single phase M 2 Si ( M = Mg , Ca , Sr ) silicides were grown using Si substrates, by thermal treatment of the substrates in the vapors of the metallic sources, M , and the electronic structures and optical property of the silicides were investigated. The electronic band structures of the silicides were calculated using the first-principles total-energy calculation program in pseudopotential schemes with plane-wave basis functions. The calculated optical reflectance spectra were also deduced from the theoretical band structures, and roughly agreed with the experimental results except for the low reflectance intensity around 2 eV. This suggests that the energy band gap of the silicides roughly agree with the calculated values of 0.15, 0.31 and 0.35 eV for Mg 2 Si , Ca 2 Si and Sr 2 Si , respectively, within the underestimation of the band gap by the density functional calculation. The optical property of the silicides is also discussed in relation to the morphological structures of the silicides.