Growth of Aluminum on Silicon: Comparison of the Si(111)7 × 7 and Si(111)δ7 × 7–D Surfaces

The initial stages of Al film formation on the clean Si(111)7 × 7 and deuterium-induced Si(111)δ7 × 7–D surfaces have been investigated using AES, LEED and TDS. Our experimental data show that epitaxial Al films form on both surfaces though the growth mode depends strongly on the substrate temperature and surface conditions. At about 90 K Al grows on the (7 × 7) surface in the quasi-Frank–van der Merwe mode forming crystallites of size 10–15 Å with Al(111)‖Si(111) and predominantly${\rm AI}[11\bar{2}]||{\rm Si}[11\bar{2}]$. The azimuthal disorder of about 10° is considerably reduced by annealing at room temperature. At and above 300 K the films grow in the Stranski–Krastanov mode with epitaxial Al(111) and Al(100) orientations. On the δ7 × 7–D surface Al grows at room temperature in the Volmer–Weber mode with epitaxial Al(111) and Al(100) islands. The film does not become continuous even at 30 ML Al, the largest Al coverage studied.