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A comparative study of the processes of metal-stimulated formation of silicon nanocrystals in SiOx–Sm structures was carried out. Samples with identical oxide matrix stoichiometry and Sm impurity content were formed using two methods: layer-by-layer deposition and coevaporation of SiO and Sm. Studies of PL and IR absorption spectra found that the admixture of samarium in samples of both types accelerates the thermally stimulated decomposition of samarium-doped SiOx films into Si and SiO2 and reduces the transition temperature of silicon nanoparticles from an amorphous state to a crystalline state. However, in (SiOx/Sm)10 multilayers, this effect is more pronounced than in single-layer films obtained using the co-evaporation method. Studying the Raman spectra of (SiOx/Sm)10 multilayers annealed at 750 °C determined that the relative volume fraction of nanocrystals in the silicon phase of the sample is ~ 38%. No line corresponding to the crystalline nc-Si was observed in the Raman spectra of samples deposited by co-evaporation and annealed under the same conditions. For these samples, a narrow line in the Raman spectrum corresponding to crystalline nc-Si appears only after annealing at 970 °C. In this case, the relative fraction of Si nanocrystals in the silicon phase of the sample was ~ 17%, 2.2 times less than for a similar multilayer annealed at 750 °C. This also indicates that, in multilayer (SiOx/Sm)10 samples, the thermally stimulated decomposition of SiOx, as well as the formation and crystallization of silicon nanoparticles, occurs at lower temperatures than in similar samples obtained by coevaporation. A possible mechanism for lowering the crystallization temperature of nc-Si in (SiOx/Sm)10 multilayers is discussed. [ABSTRACT FROM AUTHOR]

The effect of Sm on thermally stimulated decomposition of SiOx and the formation of silicon nanocrystals during high-temperature air annealing was studied by measuring the spectra of photoluminescence (PL), infrared (IR) reflection and transmission and Micro-Raman scattering (RS). The SiOx: Sm films were produced by thermal co-evaporation of silicon monoxide and metallic samarium powders in a vacuum onto polished c-Si and silica substrates. The Sm concentration varied from 0.8 to 2.0 wt. %. In the SiOx: Sm films annealed at 970 ºC, an intense PL band of silicon nanocrystals was found in the 850–900 nm region, the position and intensity of which depend on the samarium concentration. The formation of Si nanocrystals in those films is also confirmed by studying their Raman spectra. At the same time, no Si nanocrystals were found in undoped SiOx films annealed under similar conditions. The analysis of these spectra made it possible to determine the sizes of silicon nanocrystals: 3.7 nm from the PL spectra and 3.6 nm from the Raman spectra. A possible mechanism of thermally stimulated interaction of Sm atoms with the SiOx matrix is discussed. [ABSTRACT FROM AUTHOR]