Strain relaxation and surface morphology of ultrathin high ge content SiGe buffers grown on Si(001) substrate

Epitaxial growth by variable-temperature approach and structural characterization of relaxed, ultra thin 50 nm thick, high Ge content Si0.34Ge0.66 epilayers on Si(001) Substrate is demonstrated. All epilayers are grown in a single process by solid-source molecular beam epitaxy. Smooth surface and full relaxation of Si0.34Ge0.66 epilayers are achieved by introducing initial seeding layer, with high density of point defects, grown at low-temperature followed by the growth at rapidly elevating substrate temperature. Variation of growth temperature of Si0.34Ge0.66 seeding layer from 50 up to 450 degrees C exhibits strong effect on changes of surface morphology and appearance of strain in the Si0.34Ge0.66 epilayers. These epilayers grown under optimum conditions can be used as a buffer layer for the growth of semiconductor heterostructures with high hole mobility compressive strained SiGe or Ge quantum wells.