Nucleation and epitaxial growth of InAs on Si (100) by ion-assisted deposition

The nucleation mechanism and crystalline perfection of InAs on Si(100) were found to depend strongly on the substrate bias voltage V_s used to accelerate Ar ions to the growing film during triode ion-assisted deposition. Increasing the V_s value used during the first ∼10 monolayers (ML) of growth from 15 to 30 V decreased the x-ray diffraction rocking curve full width at half maximum (FWHM) by a factor of ∼2. Further increases in V _s yielded an increase in the FWHM. Reflection high-energy electron diffraction studies showed that the use of V_s=30 V promoted layer-by-layer nucleation. While three-dimensional islands formed at a critical coverage θ_cr of 2 - 3 ML for V_s=15 V, increasing V_s to 30 V increased θ_cr to ∼10 ML. The fact that V_s=30 V both promoted layer-by-layer growth and decreased the FWHM suggests that defect generation is dependent upon the nucleation mechanism.