Tilt boundary induced heteroepitaxy in chemically grown dendritic silver nanostructures on germanium and their optical properties.

Dendritic silver nanostructures were prepared by a simple dip-and-rinse galvanic displacement reaction directly on germanium surfaces. The formation and evolution of these dendrites were investigated using scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM) and energy-dispersive X-ray spectroscopy (EDX). The present results clearly show a new type of heteroepitaxy, where the large lattice mismatch between silver and germanium is accommodated at the interface by the formation of low-energy asymmetric tilt boundaries. The overgrown samples reduce the strain by introducing crystal defects. Additionally, by employing cathodoluminescence (CL) spectroscopy and imaging with a field emission gun scanning electron microscope (FEG-SEM), we provide information on the surface plasmon assisted photon emission of a stack of Ag hexagonal nanostructures. Surface enhanced Raman scattering (SERS) studies show the suitability of such Ag nanodendritic structures as SERS active substrates.