Abstract: Er-doped silicon-rich SiO₂ were prepared by ion implantation. Its microstructure was investigated by using Transmition Electron Microscope （TEM） and X-ray Diffraction （XRD） Meter. Photoluminescence and its relation with the measured temperatures were also investigated. It is shown that silicon nanocrystals, which enwrapped by amorphous Si, are observed when the implanted films are annealed above 1173K. Er ions lie in amorphous Si and couple with nc-Si through a-Si. The excitation energy from nc-Si to Er is shared by a-Si. At T ＞ 150K, energy back transfer between excited Er and a- Si decreases the PL efficiency.