The structure of hybrid radial superlattices

A new class of integrative radial crystals (Krause et al 2006 Phys. Rev. Lett. 96 165502) and radial superlattices (RSLs) (Deneke et al 2004 Appl. Phys. Lett. 84 4475) has been realized by the roll-up of semiconductor-based hybrid layer systems on a substrate surface (Prinz et al 2000 Physica E 6 828, Schmidt and Eberl 2001 Nature 410 168). After a brief overview of different approaches to realize hybrid superlattices, we review the structure of semiconductor-based radial crystals and RSLs, and provide in-depth insight into the formation of these hybrid multilayer systems. Besides various transmission electron microscopy investigations, x-ray techniques to determine the lattice parameters, strain and mismatch are discussed. The overview is meant to provide a comprehensive structural summary of semiconductor/oxide, semiconductor/organic as well as semiconductor/metal hybrid RSLs at the current state of research. Furthermore, we focus on different interface types found in RSLs. Results from laterally resolved chemical analysis techniques are discussed to complete this review paper. (topical review)