MEV ION-IMPLANTATION INDUCED DAMAGE IN RELAXED SI1-XGEX

The damage produced by implanting, at room temperature, 3-mu m-thick r elaxed 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 accumu lation of damage with increasing dose has been investigated by Rutherf ord backscattering spectrometry, optical reflectivity depth profiling, and transmission electron microscopy. An enhanced level of damage, an d a strong decrease in the critical dose for the formation of a buried amorphous layer in Si1-xGex is observed with increasing x. Electron p aramagnetic resonance studies show that the dominant defects produced by the implantation are Si and Ge dangling bonds in amorphouslike zone s 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 amorphou s layer is formed. A comparative study of the optically determined dam age in the alloys with the use of a damage model indicates a significa nt increase in the primary production of amorphous nuclei in the alloy s of Ge content x>0.04. (C) 1997 American Institute of Physics.