Investigation of morphological surface features, wetting behavior and mechanical traits under various substrate temperatures for beta iron disilicide prepared via facing-targets sputtering

Using facing-targets sputtering, semiconducting iron disilicide (β-FeSi₂) film layers were sputtered and coated on Si wafers owning (111) orientation. Under experimental conditions, the heating temperatures of the substrate (T_substrate) were varied at 525 °C, 550 °C, 600 °C and 660 °C. The acquired XRD patterns indicated a strong β(202/220) peak of around 29.1° for the β-FeSi₂ films prepared at a T_substrate of at least 600 °C. The β-FeSi₂ film surface prepared at a T_substrate of 525 °C comprised several crystallites, which were arranged to form a grain format at a higher T_substrate. The root mean square roughness for the film surface prepared at a T_substrate of 525 °C was 0.49 nm, where it increased to 0.98 nm, 2.39 nm, and 4.23 nm at T_substrate of 550 °C, 600 °C, and 660 °C, respectively. The films prepared at a T_substrate of 525 °C exhibited an average contact angle (θ_CA) of 91.15°, and improved to 103.80° after employing a T_substrate of 660 °C. These results hinted at the possibility of employing the β-FeSi₂ films prepared at all T_substrate in the hydrophobic surface application. The estimated hardness and elastic modulus of the β-FeSi₂ films prepared at T_substrate of 525 °C were 12.78 GPa and 190.98 GPa, respectively, which increased to 21.27 GPa and 248.67 GPa, respectively, for the films prepared at 660 °C. According to mechanical results, the β-FeSi₂ films prepared at 660 °C exhibited the potential to be developed for use in hard coating application.