Different Growth Modes of Al on Si(111)7 ×7 and Si(111)√3×√3–Al Surfaces

Abstract

Initial growth modes of Al atoms on Si(111)7 ×7 and on Si(111)√3×√3–Al surfaces were clarified by energy-filtered reflection high-energy electron diffraction (EF-RHEED). The growth experiments were carried out at room temperature with a deposition thickness up to about 15 Å. The EF-RHEED patterns and the intensity oscillation curves of the reflection beams were observed under the condition of the energy loss threshold E loss=30 eV of the retarding potential in order to decrease the background intensity. It was found that, in the case of the Al/Si(111)7 ×7 system, Al atoms grow as three-dimensional islands with the orientations Al(001) ∥Si(111) and Al[110] ∥Si[110] accompanying a twelvefold symmetry axis due to the combination of the fourfold symmetry [Al(001) deposition plane] and threefold symmetry [Si(111) substrate surface]. However, in the case of the Al/Si(111)√3×√3–Al system, Al atoms exhibit an almost two-dimensional layer-by-layer growth mode with Al(111) ∥Si(111) and Al[110] ∥Si[110]. In the latter case, a newly proposed entirely filled T4 site (EFT) surface structure in the transient growth stage is expected to play an important part in achieving excellent epitaxial growth of Al(111).

Optimization of Al/AlOx/Al-layer systems for Josephson junctions from a microstructure point of view

“…Even epitaxial growth of -Al2O3(111) on Al(111) has been observed under UHV conditions in a MBE system [24,25] because AlOx layers on Al(111) have the lowest calculated critical thickness above which crystalline -Al2O3 layers are thermodynamically preferred over amorphous AlOx layers [24]. Despite the lattice mismatch of 25.5% between Al and Si, epitaxial growth of Al(111) can be best achieved on Si(111) substrates [26,27]. Using Si(100) substrates, Al tends to grow in [110] direction [28], which is unwanted for the oxidation process [24].…”

Quantum Confinement Drives Macroscopic Stress Oscillations at the Initial Stage of Thin Film Growth

“…Refs. [16,17]), resulting in the formation of a single crystalline Al(111) film with an orientation relationship with the substrate described by Alð111ÞkSið111Þ and Alð110ÞkSið110Þ (see supplemental material [14] Fig. S2).…”