• Fairclough, Simon M.
• Graham, Darren M.
• Moghal, Jonathan
• Tyrrell, Edward J.
• Hardman, Samantha J. O.
• Pietzsch, Annette
• Watt, Andrew A. R.
• Lunt, Patrick J. B.
• Smith, Jason M.
• Flavell, Wendy R.
• Hennies, Franz

Abstract

We investigate the growth and the physical and optical properties of type-II heterostructured ZnTe/ZnSe colloidal nanocrystals, focusing on the role of the 7% lattice mismatch between the two materials in determining growth homogeneity and band structure. We find that the lattice mismatch between the two materials places limitations on the range of structures that can be grown, and for those in which coherent growth is achieved we present clear evidence that the low bulk modulus ZnTe cores are compressed by the higher modulus ZnSe shells, accentuating the red-shift of the excitonic state with increasing shell thickness. By employing a variety of characterization tools we build a clear picture of the core-shell architecture. We show how strain is manifested in structures with sharp core-shell interfaces and how intentional alloying of the interface can influence the growth and exciton energies. We show that a (2,6)-band effective mass model is able to distinguish between the as-grown "sharp" and "alloyed" interfaces, indicating that the alloyed structures incorporate reduced strain. © 2012 American Chemical Society.

Topics

• impedance spectroscopy
• band structure
• bulk modulus