Sb-mediated growth of Si-doped AlGaAs by molecular-beam epitaxy

Abstract

The Sb-mediated growth of Al0.65Ga0.35As is studied for Sb/III flux ratios from 0 to 2% and growth temperatures from 580 to 720 °C. The electrical properties and surface morphology are found to depend strongly on both the growth temperature and the Sb flux. As an isoelectronic dopant, Sb improves the conductivity of n-Al0.65Ga0.35As with the highest conductivities occurring at the highest growth temperatures. As a surfactant, Sb improves the surface morphology at all growth temperatures, with the most dramatic improvement occurring at 670 °C. The smoothest surface (0.2 nm rms roughness) was obtained at 700 °C using a Sb/III flux ratio of 0.02. Furthermore, we have demonstrated that the use of Sb during the molecular-beam-epitaxy growth of AlGaAs effectively eliminates the “forbidden temperature gap.”