An integrated circuit may be formed by forming a buried isolation layer in an isolation recess in a single-crystal silicon-based substrate. Exposed lateral surfaces of the substrate at the buried isolation layer are covered with a dielectric sidewall. A seed trench is formed through the buried isolation layer to expose the substrate. A single-crystal silicon-based seed layer is formed through the seed trench, extending above the top surface of the buried isolation layer. A silicon-based non-crystalline layer is formed contacting the seed layer. A cap layer is formed over the non-crystalline layer. A radiant-induced recrystallization process converts the non-crystalline layer to a single-crystal layer aligned with the seed layer. The cap layer is removed and the single-crystal layer is planarized, leaving an isolated semiconductor layer over the buried isolation layer.