Structure and low- temperature thermal relaxation of ion- implanted germanium

The structure of implantation-induced damage in Ge has been investigated us ing high resolution extended X-ray absorption fine structure spectroscopy ( EXAFS). EXAFS data analysis was performed with the Cumulant Method. For the crystalline-to-amorphous transformation, a progressive increase in bond-le ngth was observed without the presence of an asymmetry in interatomic dista nce distribution (RDF). Beyond the amorphization threshold the RDF was dose dependent and asymmetric, where the bond-length and asymmetry increased as functions of ion dose. Such an effect was attributed to the formation of t hree- and five-fold coordinated atoms within the amorphous phase. Low-tempe rature thermal annealing resulted in structural relaxation of the amorphous phase as evidenced by a reduction in the centroid, asymmetry and width of the RDF, as consistent with a reduction in the fraction of non four-fold co ordinated atoms. The results have been compared to other EXAFS studies of a morphous Ge, and it is suggested that the range of bond-lengths reported th erein is related to the sample preparation method and state of relaxation.