Novel method of strain-relaxed Si1−xGex growth on Si(100) by MBE

In order to realize high quality strain-relaxed Si1−xGex layers without island growth, the Si1−xGex layers with Ge fractions of 0.3 to 1 have been grown on Si(100) substrates by a two-step growth method. The first Si1−xGex layer was grown on Si substrates with a thickness of 50 nm at room temperature. After the growth, the substrate was annealed at 710°C for 20 min and then the 200 nm thick second layer was grown at 710°C. By this method, the strain-relaxation is well achieved in the Ge fraction range fromx = 0.3to1. This method has been found to have also the advantages that the atomic mixing at theSi/1−xGexSiinterface is prevented and the crystalline quality of Si1−xGex layers is improved.