Photoluminescence and Raman scattering in three-dimensional Si/Si _1-xGe _x nanostructures

Raman and photoluminescence measurements in Si/Si _1-xGe _x nanostructures grown by molecular-beam epitaxy under conditions close to Stranski-Krastanov growth mode, were presented. Raman spectra were collected at room temperature in a backscattering geometry using Ar ⁺ laser as the excitation source. It was found that, a Ge concentration of higher than 50% induced Ge segregation in the form of Ge-core/SiGe shell nanoclusters. The results indicate that better control over Ge segregation in three dimensional Si/SiGe nanostructures may result in optoelectronic devices compatible with CMOS technology.