Anisotropic epitaxial ZnO/CdO core/shell heterostructure nanorods.

Various surface structures and polarities of one-dimensional nanostructures offer additional control in synthesizing heterostructures suitable for optoelectronic and electronic applications. In this work, we report synthesis and characterization of ZnO-CdO nanorod-based heterostructures grown on a-plane sapphire. The heterojunction formed on the sidewall surface of the nanorod shows that wurtzite ZnO {1010} planes are interfaced with rocksalt CdO {100}. This is evidently different from the heterojunction formed on the nanorod top surface, where a ZnO (0001) top plane is interfaced with a CdO (111) plane. Such anisotropic heterostructures are determined by different surface structures of the nanorods and their polarities. Revelation of such anisotropic heterojunctions will provide a clue for understanding charge transport properties in electronic and optoelectronic nanodevices.