Raman spectroscopy of self-assembled Ge islands on Si

We present a Raman scattering study for self-organized Ge dots on Si substrate. By means of difference Raman spectroscopy technique, we have separated the Raman signals from the Ge islands and Si substrate. The wetting layer thickness and strain were estimated from the line width and peak frequency. The estimated wetting layer thickness values are comparative with the Ge dot height obtained from microscopy measurements. The strain is decreased with an increase of the thickness.