Surface morphology and reconstruction changes during heteroepitaxial growth of InAs on GaAs(0 0 1)-(2×4)

The evolution of the surface morphology and reconstruction during growth by molecular beam epitaxy of InAs on the GaAs(0 0 1)-(2×4) surface has been studied using rapid-quench scanning tunnelling microscopy. At a growth temperature of 500°C and with an As2:In flux ratio of 2:1 (growth rate 0.068 ML s−1), the two-dimensional islands formed at sub-monolayer (ML) coverages exhibit an In-terminated locally (3×1) reconstruction, in contrast to the (2×4) reconstruction of islands grown at higher flux ratios. The island size distributions exhibit scaling behaviour for all flux ratios, which also matches the scaling form for GaAs homoepitaxy on the (2×4) surface. Deposition of more than 1 ML InAs results in the formation of a disordered and alloyed wetting layer whose characteristics are independent of the flux ratio and which exhibits a (1×3) reconstruction. The role of heteroepitaxial strain in these changes is discussed.