GaAs epitaxy and heteroepitaxy: A scanning tunneling microscopy study

Abstract

In this paper, we will compare and contrast scanning tunneling microscopy images of homoepitaxially grown GaAs(100) and heteroepitaxially grown Si(100):As and Si(100):GaAs. Layers are grown by molecular beam epitaxy and imaged in situ. All samples are deposited under As-stabilized conditions. The GaAs homoepitaxial surface consists of 2×4 cells having predominantly three As-As dimers/cell. The earliest stages of heteroepitaxy are shown, including bare vicinal Si surfaces, the more ordered As-dimer terminated surface, and finally, a vicinal Si substrate with approximately two bilayers of GaAs. The later film shows essentially uniform two-dimensional topographic coverage but chemical inhomogeneity of dimer units.