MeV Ion Implantation Induced Damage in Relaxed Si1-xGex

The damage produced by implanting, at room temperature, 3-mu m-thick relaxed Si1-xGex alloys of high crystalline quality with 2 MeV Si+ ions has been studied as a function of Ge content (x=0.04, 0.13, 0.24, or 0.36) and Si dose in the dose range 10(10)-2X10(15) cm(-2). The accumulation of damage with increasing dose has been investigated by Rutherford backscattering spectrometry, optical reflectivity depth profiling, and transmission electron microscopy. An enhanced level of damage, and a strong decrease in the critical dose for the formation of a buried amorphous layer in Si1-xGex is observed with increasing x. Electron paramagnetic resonance studies show that the dominant defects produced by the implantation are Si and Ge dangling bonds in amorphouslike zones of structure similar to a-Si1-xGex films of the same x, and that the effect of increasing the ion dose is primarily to increase the volume fraction of material present in this form until a continuous amorphous layer is formed. A comparative study of the optically determined damage in the alloys with the use of a damage model indicates a significant increase in the primary production of amorphous nuclei in the alloys of Ge content x>0.04.