Dynamics of the Er1.54μm emission of Er-dope SiO_2/Si ultrathin multilayer structures

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The objectives of this study is to make an Er/SiO_2/Si ultra thin multilayer structure and to measure the energy transfer between carriers in Si and Er as a function of the thickness of the oxide layer which separates carriers and Er, in order to make clear the physical meanings of the effect of the oxide interlayer for the strong Er-related 1.54 μm emission at room temperature and to obtain a design principle for room temperature 1.54 μm luminescent devices.First, the energy transfer from photocarriers generated in Si to Er^<3+> ions is measured from the photoluminescence intensity and fluorescent decay time of the 1.54 μm emission as a function of the thickness of the oxide interlayer. Next, the reduction of the decay time under the cw illumination due to Auger quenching is measured to estimate the energy backtransfer from Er^<3+> ions to photocarriers.It is found that, though both the energy transfer and backtransfer are decreased with increasing the oxide thickness, the latter is decreased much more rapidly. In addition, it is shown that the energy transfer between carriers and Er^<3+> ions is due to the exchange mechanism. In conclusion, a thin oxide layer of 〜 2nm thickness improves the temperature quenching (γ = I_<300K>/I_<20K> = 1/2 〜 1/3 ) and gives the strongest room temperature intensity of the Er-related 1.54 μm luminescence.