The substitution of Ge atoms into ion implanted AlSb is investigated by extended x‐ray absorption fine structure spectroscopy. Our results reveal that in the as‐implanted material, the implanted Ge atoms are equally distributed between two specific sites, one surrounded by Al atoms and the other surrounded by Sb atoms. After annealing at 750 °C for 5 s, the coordination number of the Ge atoms increases from ∼3 to ∼4 indicating solid phase regrowth of the implantation induced amorphous surface layer. Moreover, in the annealed AlSb, the substitution of Ge atoms into the Al sublattice dominates with an estimatedGeAl]:[GeSb]∼0.8:0.2. These results suggest that Ge atoms act preferentially as donor species in AlSb. ©1995 American Institute of Physics.