EFFECT OF COMPOSITION AND ANNEALING ON STRUCTURAL DEFECTS IN HIGH-DOSE ARSENIC-IMPLANTED SI1-XGEX ALLOYS

The evolution of structural defects in high-dose arsenic-implanted (pe ak concentration 9 x 10(20) - 2.7 x 10(21) cm(-3)), epitaxially grown, relaxed Si1-xGex (0.15 less than or equal to x less than or equal to 0.50) during rapid-thermal annealing (RTA) has been investigated as a function of composition x and RTA using transmission-electron microsco py. The formation of monoclinic GeAs precipitates is confirmed and exa mined at high RTA temperature. A new type of three-dimensional defect (which we call a ''hair-like'' defect) is found in the alloys of x = 0 .15-0.25. Such defects have not been observed in pure silicon and thei r presence in SiGe alloys is suggested to result from interactions bet ween dislocations and GeAs precipitates. The effects of heating rate, annealing ambient, and implantation dose on both the formation of GeAs precipitates and the removal of dislocations are investigated. A poss ible influence of point defects on precipitate formation is discussed. (C) 1998 American Institute of Physics. [S0021-8979(98)06820-0].