Al Islands on Si(111): Growth Temperature, Morphology, and Strain

Comprehensive structural studies of thin island Al films with a thickness of 20–50 nm deposited by magnetron sputtering on Si(111) substrates in an argon plasma at a pressure of 6 × 10 –3 mbar and a temperature ranging from 20 to 500°C are presented. The morphology and microstructure of the films are studied using XRD, SEM, EDS, and TEM methods. It is found that most of the islands are Al {001} and Al {111} crystallites with lateral sizes of 10–100 nm, differently conjugated with the Si(111) substrate. At room temperature of the substrate, only Al {001} crystallites are epitaxially formed on it. The epitaxial growth of Al {111} crystallites is predominant as the substrate temperature increases above 400°C. The influence of the temperature of the Si(111) substrate on the process of epitaxial growth of crystallites, the dynamics of their shape, and structural perfection is shown. It is found that crystallites epitaxially connected to the substrate experience deformation at ε = 7 × 10 –3 and ε = –2 × 10 –3 for Al {001} and Al {111}, respectively. It is shown that for thin island Al films on Si(111), the dependence of the number of crystallization centers and the particle growth rate on the supercooling temperature is consistent with the band model of crystallization. At the same time, a shift in the characteristic temperatures for the zone boundaries is observed due to the properties of the substrate. This must be taken into account when engineering the surface morphology and structural perfection of crystallites in Al island magnetron films.