Growth and properties of silicon heterostructures with buried nanosize Mg_2Si clusters

摘要

The technology of solid-phase growth of nanosize islands of magnesium silicide on Si (111) 7x7 with narrow distributions of lateral size and height (60 - 80 and 5 - 7 nanometers, respectively) and density of up to 210~9 sm~(-2) is proposed. A 20-50 nm thick Si layer has been grown upon these islands. Basing on the data of AES, EELS, AFM and IR spectroscopy, a conclusion is made that the Mg_2Si islands remain in depth of the Si layer. The suggestion is made that sizes, density and crystal structure of the buried magnesium silicide clusters preserves. It is shown, that the system of three as-grown layers of buried clusters has smoother surface than the one layer system. The contribution of the Mg_2Si clusters into the dielectric function is observed at the energy 0.8 - 1.2 eV, it is maximal if the clusters are localized on the silicon surface. It is shown, that with increase of the number of Mg_2Si cluster layers their contribution increases into the effective number of electrons per a unit cell and effective dielectric function of the sample.