DIRECT OBSERVATION OF THE 2-STAGE EXCITATION MECHANISM OF ER IN SI

In Er-doped silicon we have found direct evidence for the formation of the Er-related intermediate state that is a precursor of the final 4f -electron excited state responsible fur the 0.8 eV luminescence. Time- resolved photoluminescence following band-gap illumination shows disru ption of this center by a THz pulse from a free-electron laser. The de cay of the intermediate state could be directly monitored in this doub le-beam experiment and a lifetime of approximately 100 mu s has been f ound. Tn this way the most characteristic step in die excitation mecha nism of the Er ion in silicon has been revealed experimentally. [S0031 -9007(98)07761-8].