EVIDENCE OF GE ISLAND FORMATION DURING THERMAL ANNEALING OF SIGE ALLOYS - COMBINED ATOMIC-FORCE MICROSCOPY AND AUGER-ELECTRON SPECTROSCOPY STUDY

The effect of thermal annealing on the composition and morphology of t he surface of strained SiGe layers grown on Si is investigated in the temperature range 400-900 degrees C, We show that Ge segregation start s at 400 degrees C and increases with increasing temperature. Above 70 0 degrees C, strain relaxation leads to the formation of islands on th e surface. By combining atomic force microscopy and Auger electron spe ctroscopy we demonstrate that these islands are Ge rich and that at 90 0 degrees C rather pure Ge islands are formed on a Si rich underlying layer. (C) 1998 American Vacuum Society.