Effects of Ga-induced reconstructed surfaces and atomic steps on the morphology of GaSb islands on Si(1 0 0)

Abstract

The effects of the Ga-induced reconstructed surface and atomic step type on the shape and morphology of GaSb islands on a Si(100) surface were studied using ultrahigh-vacuum scanning tunneling microscopy and atomic force microscopy. Though both anisotropic elongated islands and isotropic islands were formed on clean Si and Ga/Si(100)-2×3 substrates, isotropic islands were dominantly formed on Ga/Si(100)-2×2 substrates at 300°C. The density and size of GaSb islands on 2×2-Ga at 300°C were estimated to be 4.9×1010cm−2 and 29.1nm, respectively. The difference in the GaSb island shapes could be caused by the terrace and step of the substrate surface being changed by step rearrangement due to the deposition of Ga atoms at high temperatures. Above 350°C, the density and size of islands decreased to 2.7×109cm−2 and increased to 62.0nm, respectively. In the initial growth stage, scanning tunneling microscopy results revealed that a Sb/Si(100)-2×1 reconstructed surface was formed above 350°C. The large islands were assumed to aggregate from the surface diffusion of each atom because the Sb-terminated Si surface is inactive against Ga and Sb atoms. The type of the reconstructed surface is also suggested to affect the density and size of the islands.