Anisotropic Strain-Induced Curvature in Type-II CdSe/CdTe Nanorod Heterostructures

Type-II band-offset CdSe/CdTe nanorod heterostructures with curved and linear shapes have been synthesized and examined with atomic-resolution transmission electron microscopy techniques. Strain from growth of larger-lattice CdTe partly on the sides of CdSe nanorod seeds is shown to lead to an overall curvature in the rods. Lattice expansion from the inner to the outer portion of the curved region exceeds the expected lattice mismatch between the two materials because of the buildup of an unusual compressive strain in the CdSe. In contrast, exclusive tip growth results in linear barbell-shaped heterostructures that do not exhibit strain-induced curvature. The ability to vary the anisotropie lattice strain should allow control over the underlying electronic structure, providing new approaches to directing photogenerated carriers that may facilitate incorporation of nanorod heterostructures in various energy applications.