Synthesis and characterization of well-aligned Cd–Al codoped ZnO nanorod arrays

Well-aligned Cd–Al codoped ZnO nanorod arrays have been synthesized on Ni catalyst-coated p+-Si (1 1 1) substrates by a chemical vapor deposition technique. It is demonstrated that the obtained codoped ZnO nanorod arrays are single crystallinity with the wurtzite hexagonal phase and preferably grown along the [0 0 0 1] direction. The optical properties of the nanostructures are characterized by the Raman and photoluminescence techniques. The rectifying characteristics of the p–n heterojunction composed of codoped ZnO nanorod arrays and a p+ silicon chip are observed. The possible growth process based on VLS mechanism is proposed for the formation of codoped ZnO nanorod arrays.