Size-and doping-dependent time-resolved photoluminescence of doped Si nanocrystals

摘要

Time-resolved photoluminescence (PL) has been studied for B-and Sb-doped Si nanocrystals (NCs) fabricated by ion beam sputtering and annealing. For B-doped Si NCs, the PL intensity as well as the PL lifetime (τ_(PL)) increases as NC size (d) varies from 1.5 to 2.6nm, similar to the case for undoped Si NCs, but with further increase of d, they decrease, possibly resulting from the increase of optically less active NCs with the increase of NCs containing more dopants. The PL intensity and τ_(PL) monotonically decrease with increasing doping concentration (nD), irrespective of doping element. Si NCs show smaller τ_(PL) in B doping than in Sb doping over the full range of n_D. The sharp decrease in PL intensity, accompanied by the gradual decrease in τ_(PL) for the higher n_D of Sb, may be attributed to Auger recombination due to the presence of Sb inside Si NCs. The higher PL quench rate by Sb compared to B could be attributed to better ionization of Sb dopants in Si NCs.