Ion-irradiation-induced suppression of three-dimensional island formation during InAs growth on Si(100)

Abstract

Nucleation and growth of InAs on Si(100) substrates during ion-assisted deposition has been investigated. Reflection high-energy electron diffraction studies showed that InAs films nucleated by the Stranski–Krastanov (SK) mechanism. Ar ion irradiation with energies E near 30 eV and a flux of 4 ions per deposited atom prolonged the layer-by-layer stage of SK nucleation. The transition from layer-by-layer to island growth was at 2–3 monolayers (ML) for growth temperature Ts=380 °C and E=13 eV. With Ts=380 °C and E=28 eV, on the other hand, layer-by-layer growth was maintained up to ∼10 ML. A further increase in E to 38 eV reduced the transition coverage to ∼7 ML. In addition, epitaxial temperatures were reduced from >345 to <250 °C by increasing the Ar ion energy E from 13 to 38 eV. Cross-sectional transmission electron microscopy studies of 500 nm thick films showed that increasing E from 13 to 28 eV during the nucleation stage smoothened the surface and improved the crystalline perfection. The effect of ion bombardment on the nucleation mechanism is explained as being due to ion-induced dissociation of three-dimensional islands and ion-enhanced surface diffusion.