GAAS EPITAXY AND HETEROEPITAXY - A SCANNING TUNNELING MICROSCOPY STUDY

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 2X4 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. © 1990, American Vacuum Society. All rights reserved.