Si incorporation during molecular beam epitaxy growth of GaAs and preferential attachment of Si atoms at misorientation steps

Abstract

The effect of Si doping on the growth process of GaAs on the singular GaAs(001) surface and the attachment kinetics of Si atoms at misorientation steps on vicinal GaAs(001) surfaces have been studied by reflection high-energy electron diffraction (RHEED). During the successive growth of undoped and doped layers on the singular surface, its smoothness degrades due to Si incorporation at concentrations as low as 1016 cm−3. At high concentrations the surface ordering of undoped layers grown before and after the doped layers differs considerably. As evidenced by RHEED intensity recovery curves recorded after growth interruption the surface diffusion processes are hindered by Si atoms or clusters. The behavior of the RHEED intensity during Si deposition on vicinal GaAs(001) surfaces tilted toward the (111)Ga plane is used to analyze the surface migration kinetics with a competition between incorporation of Si atoms at step edges and their islanding on terraces. For a misorientation of 2° and a substrate temperature of 580 °C a self-organized in-plane incorporation of Si atoms in a (3×2) symmetry along the step edges is observed. For Si depositions not exceeding the amount to be attached at the step edges, the GaAs growth can be continued without adverse effects on the growth front.