Luminescence Property Of Erbium-doped Silicon-rich Oxide Films

Recently, more and more researchers have focused on silicon photonics, which combines the merits of opto-electronics and micro-electronics. It can not only increase the transportation rate and decrease the energy consumption of the devices by using photons as the information carriers, but also cut the fabrication cost by employing the current silicon-based integration technique to achieve the large-scale applications. However, the silicon-based light source that can be integrated into the silicon photonic chip is still lack, which restricts the development of the silicon-based photonics. Erbium-doped silicon-rich oxide (SROEr) film is a promising candidate material for silicon-based light sources since its fabrication is compatible with current silicon-based integration technique and the luminescence peak of Er3+(1.54μm) corresponds to the low-loss window of silica-based fibers. Consequently, the achievement of highly-efficient luminescence from SROEr matrix is imperative.In this thesis, abundant amount of silicon nanocrystals (Si NCs) and stable luminescence centers were introduced into the SROEr films by the control of the fabrication process. The sensitization of both Si NCs and luminescence centers to Er3+is achieved, and the SROEr films with promising luminescence properties were obtained. The primary achievement of this work is described as follow:(1) SRO films with excellent luminescence properties were acquired by the optimization of the fabrication technique. SRO films with tunable compositions and micro-structures were fabricated by different methods (electron-beam evaporation and magnetron sputtering) and by the modulation of the post thermal annealing process, such as the time and temperature of the annealing. Si NCs of denser and better-quality can be obtained in the loose and porous SRO films, which possesses superior luminescence properties than those in dense SRO films.(2) The tunability of the luminescence from Si NCs and luminescence centers in SROEr films is achieved. SROEr films with different amounts of silicon excess were fabricated by electron-beam evaporation. Si NCs of larger sizes were obtained in the SROEr films with higher silicon excess, whose luminescence regime of amorphous network is small and the luminescence from Si NCs dominates. While for the SROEr films with lower silicon excess, abundant amount of luminescence centers (mainly Si=O bonds) co-exists with Si NCs in the network, and the luminescence from luminescence centers dominate. Equivalent luminescence intensity from luminescence centers and Si NCs can be obtained in the SROEr films with moderate amount of silicon excess.(3) The fabrication of SROEr films with stable luminescence centers (mainly Si=O bonds) is achieved by electron-beam evaporation. And the sensitization of both the luminescence centers and Si NCs to Er3+is investigated. The optimal luminescence properties of Er3+were obtained when the equivalent luminescence intensity of luminescence centers and Si NCs was achieved, where the optimal coupling between the sensitizers and Er+can be achieved.(4) The control of the micro-structures and sizes of Si NCs is achieved by modulating the fabrication process of SRO and SROEr films, and the evolution of luminescence from Er3+with the micro-structures and sizes of Si NCs is investigated. SRO and SROEr films with various amounts of silicon excesses were fabricated by magnetron sputtering. Smaller sized and separated Si NCs were obtained in the films with lower silicon excess. While larger sized and overlapped Si NCs were obtained in the films with higher silicon excess, where a higher energy transfer efficiency from Si NCs to Er3+but lower luminescence intensites of Si NCs and Er3+were obtained due to the non-radiative recombination at the interface of the overlapped Si NCs.(5) The explanation on the luminescent saturation of Er3+in highly-doped SROEr films is provided. We attributed this phenomenon to the separated out of the large sized Er2O3in highly-doped SROEr films, where the coupling efficiency between Si NCs and Er3+is degenerated.