A novel way of integrating epitaxial Si and carbon (C) doping capabilities within an existing solid-source III-V molecular beam epitaxy system by means of electron-beam evaporation is reported. By significantly increasing the Si evaporation rate over conventional effusion cells, this technique offers a practical way of growing high Si content (III-V)-Si alloys and superlattices. The use of GaAs-Si alloys with adjustable lattice constants for GaAs on Si growth with improved crystalline quality over previous methods is also demonstrated. Both uniform layer and delta-doped C in GaAs (p-type concentration up to the mid 10(19)/cm3 range) are demonstrated with carrier mobility comparable to other doping sources. These extended capabilities should find wide applications ranging from material synthesis to III-V devices and technology.