Synthesis of crystalline Mg2Si films by ultrafast deposition of Mg on Si(111) and Si(001) at high temperatures. Mg/Si intermixing and reaction mechanisms

• Published in: Materials chemistry and physics 2021-01, Vol.258, p.123903, Article 123903
• Main Authors: Gouralnik, Alexander S., Shevlyagin, Alexander V., Chernev, Igor M., Ustinov, Alexander Yu, Gerasimenko, Andrey V., Gutakovskii, Anton K.
• Format: Article
• Language: English
• Subjects: Cross-sectional HRTEM; Crystal structure; Deposition; Evaporators; Intermetallic compounds; Magnesium compounds; Magnesium silicide; Metal silicides; Photovoltaic cells; Pulse duration; Reaction mechanisms; Silicides; Silicon substrates; Solar cells; Solid state intermixing mechanism; Ultra-fast deposition
• ISSN: 0254-0584; 1879-3312
• DOI: 10.1016/j.matchemphys.2020.123903

Mg2Si films have been grown on Si(111) and Si(001) surfaces at ~ 387–477 °C by ultra-fast deposition in vacuum. The original pulse-type evaporator used allows Mg deposition rates of ~103–104 nm/s which provide effective accumulation of Mg on hot Si surfaces despite its fast re-evaporation. The silicide films at different stages of formation and growth have been obtained by varying the pulse duration, Mg deposit amounts and substrate temperatures. The local structure and crystal quality of the obtained Mg2Si films have been studied. The mechanism of the Mg2Si film formation and growth process is considered. The role of high temperatures in the formation of film texture is demonstrated. The existing to date experimental data on Mg–Si intermixing and Mg2Si formation are explained. Technologies of Si/Mg2Si solar cells can be based on these results. [Display omitted] •Different stages and mechanism of Mg2Si formation on Si above 300–400 °C are studied.•Textured Mg2Si films grow on Si(111) and (001) by fast deposition of Mg at 400 °C.•By XRD and HRTEM data, the films' crystal quality is the best to date.•11 nm-thick film is continuous, 45-90 nm-thick films have the columnar structure.•Texture forms during nucleation at high T; only the best-oriented nuclei are stable.