  Cuprous oxide (Cu2O) nanowires were grown by a simple, catalyst-free thermal
oxidation method starting from a copper foil substrate. Wire growth was
performed at different conditions by varying oxygen partial pressure and
heating temperature, and produced structural defects such as stacking faults
and twin structures of grown nanowires were characterized by transmission
electron microscopy. A moderate oxygen partial pressure ~5% with a relatively
high temperature at 500 oC is found to be an optimal condition for growing
high-quality Cu2O nanowires, while either lowering temperature or enhancing O2
partial pressure can yield higher density of planar defects. In order to
further investigate optical properties of grown nanowires, photoluminescence
measurements were also performed and correlated with structural
characterization results, indicating that increase of structural defects such
as stacking faults and twins tended to enhance broad defect-related emissions
and suppress the exciton emissions near Cu2O band-edge.
