Epitaxial growth of three-dimensionally mesostructured single-crystalline Cu₂O via templated electrodeposition

Significant efforts have been made over the past few decades to realize functional three-dimensional photonic crystal devices including zero-threshold lasers, waveguides, light-emitting diodes (LEDs), and solar cells; however, progress has been limited because of difficulties in creating three-dimensional photonic crystals from single-crystal materials. Most have been formed from polycrystalline materials and thus have generally exhibited poor electronic properties. Realization of materials containing complex three-dimensional mesostructures, in single-crystal form, remains a significant challenge. Here, we demonstrate the epitaxial growth of three-dimensionally mesostructured Cu₂O by bottom-up electrodeposition through a 3D silica colloidal template. Not only is the templated Cu₂O single crystal, but when the electrodeposition continues past the colloidal template, the crystallinity of the overlying solid Cu₂O appears to be improved because the template blocks threading dislocations, resulting in substantial reductions in the dislocation density of the overlying solid Cu₂O.