Very Thin 2D GaAs Films on Si During the Early Stages of Growth by MBE

Abstract

ABSTRACTGaAs samples deposited on Si by molecular beam epitaxy (MBE) with a graded thickness of 0–3 nm initially show the presence of a metastable two dimensional (2D) layer containing Ga and As. In the thicker regions of the wedge samples, islands (3D topography) form in the presence of the 2D sea, i.e., Stranski – Krastanov growth. Compositional profiles of these wedges were made with in situ Auger electron spectroscopy (AES) which has allowed the identification of at least four regimes of growth. Lattice images from cross – sectional transmission electron microscopy (XTEM) are consistent with the AES profiles. Substrate temperature during deposition of the films has a strong effect on film topography, as does the beam – flux ratio on film stoichiometry.