Strain-driven alloying in Ge/Si(100) coherent islands

Ge/Si(100) island size distributions were monitored for coverages between 3 .5 and 14.0 monolayers at growth temperatures from 450 to 600 degrees C. Fe atures in these distributions are correlated with characteristic island mor phologies. The mean dome cluster size increased and the onset of island dis location was delayed as the growth temperature increased. At 600 degrees C, very large hut clusters are formed. This behavior is attributed to strain- assisted alloying of the Ge clusters. Energy dispersive x-ray analysis conf irms Si diffusion into the Ge clusters at 600 degrees C. An atomistic elast ic model supports the interpretation that alloying is driven by strain ener gy enhancement near the island perimeters.