RAPID THERMAL ANNEALING OF ARSENIC-IMPLANTED SI0.6GE0.4 ALLOYS - TEMPERATURE EFFECTS

Structural transformations produced in strain-relaxed, low-dislocation -density Si0.6Ge0.4 films by As+ implantation and rapid thermal anneal ing were studied by transmission electron microscopy and x-ray microan alysis. The type of residual defects was found to be strongly dependen t on annealing temperature. Only perfect dislocation loops were observ ed in implanted layers after annealing at 800 degrees C. Annealing at higher temperature (900 degrees C) results in complete removal of irra diation damage accompanied by the formation of GeAs precipitates of mo noclinic phase and spherical shape. The results show that the behavior of As in Si-Ge alloys during thermal processing is remarkably differe nt from that in Si. In particular, precipitation of As atoms in Si0.6G e0.4 was found at an As concentration of 9 x 10(20) cm(-3) which is at least one order of magnitude lower than the critical As concentration for As precipitation in Si. (C) 1996 American Institute of Physics.