Optical excitation of Er ions with 1.5 μm luminescence via the luminescent state in Si nanocrystallites embedded in SiO2 matrices

Optical excitation bands have been investigated for Er-doped SiO2 films, including Si nanocrystallites as sensitizers. The Er-doped films with photoluminescence at 1.5 μm were fabricated using a laser ablation technique. It is found that the major continuous portion of the excitation bands for Er ions completely coincides with that of Si nanocrystallites at room temperature. Thus, it has been demonstrated that the second indirect absorption band of Si nanocrystallites can be used for efficient excitation of Er ions. The photoluminescence spectroscopy revealed that Er ions are possibly excited from the ground state 4I15/2 to the first excited state 4I13/2 by the energy transfer from the singlet excitons in Si nanocrystallites.