Luminescence of Bi₄Ge₃O₁₂ (BGO) crystals under KrF and XeF laser excitation

The results of a study of the luminescence of Bi₄Ge₃O₁₂ (BGO) crystals at low excitation intensity by a KrF laser (hv = 4.98 eV) and a two-photon excitation by an intense XeF laser (2hv = 7 eV) confirm that the main emission band (2.5 eV) is due to optical transitions in local Bi³⁺ ions. Under intense KrF laser excitation a broad structureless emission is observed. This emission may be assigned to the intraband optical transitions of highly excited electrons in the conduction band.