Regrowth mechanism for oxide isolation of GaAs nanowires

Oxide-isolated GaAs nanowires (NWs) were obtained through a lithography-free method in which axial growth of NWs coated in aluminum oxide (Al₂O₃) is restarted using an annealing step. NWs are grown using the vapor-liquid-solid method and coated in nanometer thin oxide films using atomic layer deposition. Continued growth at the oxide-coated nanoparticle (NP) occurs after the thermally-induced fracture of the oxide during annealing. This oxide fracture is observed to depend on NP diameter, oxide thickness and annealing temperature. A thermal expansion mismatch model for stresses on the oxide shell is put forward to explain these results.