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 degreesC. The surface morphology and electrical properties are found to strongly depend on both the growth temperature and Sb flux. As an isoelectronic dopant, Sb improves the conductivity of n-Al0.65Ga0.35As and reduces the conductivity of p-Al0.65Ga0.35As. As a surfactant, Sb improves the,surface morphology of Al0.65Ga0.35As at all growth temperatures with the most dramatic improvement occurring at 670 degreesC. The smoothest surface (0.2 nm root-mean-square roughness height) was obtained at 700 degreesC using a Sb/III flux ratio of 0.02. This work demonstrates that Sb-mediated molecular beam epitaxy growth of n-AlGaAs effectively eliminates the "forbidden temperature gap" for device quality n-AlGaAs. (C) 2004 American Vacuum Society.