X-ray-excited optical luminescence of impurity atom in semiconductor

We observed the x-ray-excited optical luminescence (XEOL) of erbium-doped silicon (Si:Er) thin films to make a site-selective x-ray absorption fine structure (XAFS) measurement of an optically active Er atom. The undulator beam was used for the increment of the electron population in the excited state, and following XEOL at an infrared wavelength of 1.54 µm with minimum absorption loss in the host Si was detected. The edge-jump and XAFS oscillation were successfully obtained at the Er L_III-edge. This spectrum originated from inner-shell excitation and relaxation of only the optically active Er atom, indicating that site-selectivity at an atomic level was achieved.