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

本研究的目的是制作Er/SiO_2/Si超薄多层膜结构，测量Si中载流子与Er之间的能量传递随分隔载流子和Er的氧化层厚度的变化，以阐明氧化层对室温下与Er相关的1.54μm强发射的影响的物理意义，并得到室温1.54μm发光器件的设计原理。根据1.54μm发射的光致发光强度和荧光衰减时间作为氧化物夹层厚度的函数来测量离子。其次，测量了由于俄歇猝灭引起的连续光照射下衰减时间的缩短，以估算Er~(2+)&lt；3+&Gt；离子到光载流子的能量回传，发现虽然能量传递和回传都随着氧化层厚度的增加而减小，但后者下降得更快。此外，研究还表明，载流子与Er^&lt；3+&gt；离子之间的能量传递是由交换机制引起的。总而言之，厚度为2 nm的薄氧化层改善了Er的温度猝灭(γ=I_&lt；300K&gt；/I_&lt；20K&gt；=1/2~1/3)，并提供了与Er相关的1.54μm发光的最强的室温强度。

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.