Enhanced Yb3+-related 0.98 μm emission in porous silicon and its time decay characteristics

A strong enhancement in the intensity of the ∼0.98 μm emission (2F5/2→2F7/2) of Yb3+-ions in porous silicon is obtained by adding a pre-annealing process to host porous silicon in O2 or H2 prior to Yb3+-ion incorporation and subsequent post-dope annealing. The luminescence intensity shows a small temperature quenching, decreasing from 20 K to 300 K by a factor of ∼10. The time decay measurements show that there are two major Yb3+-related luminescence centers in Yb-doped porous silicon. One is a fast decaying center with a decay time of ∼30 μs at 20 K which decreases rapidly with increasing temperature. The other is a slowly decaying center with an almost temperature independent decay time of ∼400 μs. The latter is responsible for the small temperature quenching of Yb3+-related 0.98 μm emission.