Wurtzite to zinc blende phase transition in GaAs nanowires induced by epitaxial burying.

We bury vertical free-standing core-shell GaAs/AlGaAs nanowires by a planar GaAs overgrowth. As the nanowires get buried, their crystalline structure progressively transforms: whereas the upper emerging part retains its initial wurtzite structure, the buried part adopts the zinc blende structure of the burying layer. The burying process also suppresses all the stacking faults that existed in the wurtzite nanowires. We consider two possible mechanisms for the structural transition upon burying, examine how they can be discriminated from each other, and explain why the transition is favorable.