Local structure of 1.54-μm-luminescence Er3+ implanted in Si

Extended x-ray absorption fine structure measurements from Er-implanted Czochralski-grown Si samples, which exhibit strong luminescence at 1.54 μm, reveal a local sixfold coordination around Er−not of Si−but of oxygen atoms at an average distance of 2.25 Å. By contrast, similar concentrations of Er implanted in high purity float-zone Si samples, which are essentially optically inactive, show that Er is coordinated to 12 Si atoms at a mean distance of 3.00 Å.