STRAIN AND DEFECT MICROSTRUCTURE IN ION-IRRADIATED GESI SI STRAINED LAYERS AS A FUNCTION OF ANNEALING TEMPERATURE/

High-energy (1 MeV), ion irradiation of GeSi/Si strained layers at ele vated temperatures can cause strain relaxation. This study examines th e defects responsible for relaxation and for the evolution of the stra in during subsequent annealing. Three distinct annealing stages are id entified and correlated with the defect microstructure. In the tempera ture range from 350 to 600 degrees C, a gradual recovery of strain is observed. This is shown to correlate with annealing of small defect cl usters and the growth of voids. The voids are visible at annealing tem peratures in excess of 600 degrees C, consistent with an excess vacanc y concentration in the irradiated alloy layer. In the temperature rang e 600-750 degrees C, the strain recovers to a maximum value which is c orrelated with the ripening of voids, dissolution of alloy layer {113} rodlike defects, and {113} planar interstitiai defects in the substra te. At temperatures in the range 750-1000 degrees C, strain relaxation is observed and is correlated with the growth of intrinsic dislocatio ns within the alloy layer. These intrinsic, looplike dislocations nucl eate at the alloy-substrate interface and grow within the alloy layer, toward the surface. (C) 1998 American Institute of Physics.