Effect of nucleation mechanism on planar defects in InAs on Si (100)

Abstract

Suppression of three-dimensional (3D) island nucleation during growth of InAs on Si (100), achieved by using very low energy, high-flux Ar ion irradiation, reduced planar defect densities. For 13 eV ion irradiation, 3D islands nucleated after ∼2 monolayers (ML) of deposition, similar to conventional molecular beam epitaxy. High-resolution transmission electron microscopy studies of nominally 18-ML-thick films showed 3D InAs islands with {111} facets. A high density of {111} twins and stacking faults was observed adjacent to many of the {111} facets. Most of these defects propagated into the film upon further growth. When nucleation was carried out with 28 eV ion irradiation, flat InAs films were observed for thicknesses up to ∼10 ML. The 3D islands that nucleated at higher thicknesses were flatter with less faceting than in the 13 eV case. The density of planar defects in the initial nucleation layer and in thicker InAs films was reduced when 3D island nucleation was suppressed. These results indicate that planar defects formed directly on the {111} facets of the 3D islands.