Publications Repository - Helmholtz-Zentrum Dresden-Rossendorf

Ion implantation can be a very useful technique to dope silicon nanowires heavily to improve their electrical properties. However, heavy implantation can amorphize the nanowires completely. Subsequently, a complete recovery of their crystallinity, which is of utmost importance to ensure their improved electrical properties, becomes nontrivial. We have performed a controlled study of nanowire recrystallization using vertical Si < 111 > nanowires that were amorphized during doping by arsenic ion implantation. Upon a single-step thermal anneal by furnace (500-650 degrees C) or by rapid thermal annealing (800-1200 degrees C), the nanowires turned partly single-crystalline from the bottom and partly polycrystalline from the top, owing to a competition between solid phase epitaxial regrowth from the substrate and random nucleation and growth, probably originating from the free surface. A complete recrystallization of the amorphized nanowires was achieved only after the furnace-annealed nanowires were annealed for a second time at a higher temperature (950-1200 degrees C). The polycrystalline grains formed during the first anneal were successfully aligned to the < 111 > direction, leading to a recovery of the single-crystalline structure of the nanowires.