Growth and characterization of self-assembled Ge-rich islands on Si

Ge-rich islands have been grown on Si (100) substrates by molecular beam epitaxy. Their density and size distribution are analysed by atomic force microscopy as a function of growth temperature, growth rate and Ge coverage. Overgrown islands have been studied by transmission electron microscopy, Raman scattering and photoluminescence. The first results of photocurrent spectroscopy on Si/Ge/Si pin diodes show the expected shift of the energy gap. Based on these results, novel device applications of Ge-rich islands in Si are proposed.