Influence of process parameters on the microstructure of scandium films deposited by electron-beam evaporation

Microstructures of scandium films deposited on molybdenum (Mo) substrates by electron-beam evaporation are investigated. Influences of substrate temperatures and deposition rates are considered. It is found that the microstructural changes of scandium films with the substrate temperatures are consistent with the reported structure-zone models. Sc films, deposited at 5 nm/s with the temperature range of 373-923 K, as well as deposited at 923 K with the deposition rate from 0.5 to 5 nm/s, show a (002) preferred orientation. Both the texture coefficients of (002) peaks and the grain sizes increase with the substrate temperature. For films deposited at various deposition rates, the films show smoother surfaces at the lower deposition rate. Moreover, the grain sizes first increase with the increasing deposition rate and then decrease with it. The largest grain size (∼246 nm) is obtained at the deposition rate of 5 nm/s. The texture coefficients of the (002) preferred orientation decrease when the deposition rate increases from 0.5 nm/s to 5 nm/s. And the preferred growth of the film disappears at deposition rate of 10 nm/s.