Ar+ irradiation of Si nanocrystal-doped SiO2: Evolution of photoluminescence

We report the evolution of photoluminescence (PL) of Si nanocrystals (nc-Si) embedded in a matrix of SiO2 during Ar+ ion bombardment. The integrated intensity of nc-Si PL falls down drastically before the Ar+ ion fluence of 1015 ions cm 2, and then decreases slowly with the increasing ion fluence. At the meantime, the PL peak position blueshifts steadily before the fluence of 1015 ions cm 2, and then changes in an oscillatory manner. Also it is found that the nc-Si PL of the Ar+-irradiated sample can be partly recovered after annealing at 800 8C in nitrogen, but can be almost totally recovered after annealing in oxygen. The results confirm that the ion irradiation-induced defects are made up of oxygen vacancies, which absorb light strongly. The oscillatory peak shift of nc-Si can be related to a size-distance distribution of nc-Si in SiO2.