A line‐source electron beam has been used to melt and recrystallize isolated Si layers to form Si‐on‐insulator structures. Heat flow calculations for these layered structures have been developed which correctly predict the observed recrystallization. Using sample sweep speeds of 100–600 cm/s and peak power densities up to 75 kW/cm2in the 1×20‐mm beam, we have obtained single‐crystal areas as large as 50×350 &mgr;m. Seed openings to the substrate are used to control the orientation of the regrowth and the heat flow in the recrystallization film.