Ga-ZnS nanowire heterojunctions, uniformly sheathed with very thin silica nanotubes, are prepared via thermal evaporation of SiO, Ga2O3, and ZnS powder precursors followed by thermo-chemical reaction. Some nanowires have a single junction (Figure, top), while others have multiple junctions (bottom). The Ga-ZnS interface is particularly sensitive to electron-beam irradiation (EBI), making possible an EBI-driven switch.