The time evolution of the 1.54 µm Er3+ photoluminescence intensity of Er-doped silicon following a 30 µs excitation pulse in investigated. It is found that a 9 K, the 1.54 µm luminescence from Er3+ continues to increase up to 50 µs after the pulse is terminated, when excess photocarriers no longer exist. The provides the first direct experimental evidence that a state in the forbidden gap of silicon acts as the gateway to the excitation of Er3+. Further analysis indicates recombination of bound excitons to be the most likely excitation mechanism.

Appl. Phys. Lett.
Photonic Materials

Shin, J. H., van den Hoven, G. N., & Polman, A. (1995). Direct experimental evidence for trap-state mediated excitation of Er3+ in silicon. Appl. Phys. Lett., 67, 377–379.