Evolution of the Local Environment Around Er Upon Thermal Annealing in Er and O Co-implanted Si

We present extended x-ray absorption fine structure (EXAFS) analyses of the Er L(III) edge in Er-doped (100) Si samples. The samples were prepared by multiple implants of Er and O resulting in the incorporation of 1x10(19) Er/cm(3) and 1x10(20) O/cm(3) in a 2.3-mu m-thick amorphous layer. It has been found that the local environment around the Er sites, which consists of six Si first neighbors in the amorphous layer, evolves towards a mixed coordination with O and Si atoms after epitaxial regrowth of the layer at 620 degrees C for 3 h. A further thermal treatment at 900 degrees C removes the residual Er-Si coordination and produces a full oxygen coordinated first shell with an average of 5 O neighbors. The effects of the different thermal processes on the high resolution spectra of the 1.54 mu m Er photoluminescence were also measured and related to the EXAFS results.