On the Growth, Structure, and Optical Reflection of Magnesium Silicide Films Grown on Porous Silicon under High-Vacuum Conditions

The growth of magnesium silicide on porous silicon under high vacuum conditions (10^–5–10^‒6 Torr) without the chemical removal of silicon oxide and in a limited temperature range of preliminary annealing (T_a = 450°C) is tested for the first time. It is found that the minimum substrate temperature at which deposited magnesium begins to destroy silicon oxide and interact with silicon by forming magnesium silicide (Mg₂Si) is 290°C. In the solid phase reaction of magnesium with porous silicon, the optimum temperature at which, after the destruction of silicon oxide, the formation of a continuous Mg₂Si film begins is 350°C. It is shown that, at an annealing temperature T_a = 420°C, only a Mg₂Si island film of good crystalline quality is formed. The formation of magnesium silicide in all cases is confirmed by X-ray diffraction, scanning electron microscopy, Raman spectroscopy, or Raman micromapping. It is established that the reflection spectrum of the Mg₂Si/PS/Si system corresponds to the reflection from porous silicon with a partial increase at 500–900 nm due to the contribution to reflection from magnesium silicide, which increases with increasing film thickness. It is proved that after the heat treatment of porous silicon and the growth of magnesium silicide with a thickness of up to 90 nm, PS photoluminescence is retained, the radiation of which is recorded with partial attenuation in the Mg₂Si film without changing the spectral composition, both immediately after growth and after long-term storage under atmospheric conditions (up to 8 months).