Publication Date:
2015-05-05
Description:
Silicon nanocrystals formed in the annealed SiN x /Si 3 N 4 superlattices are attractive for research due to the smaller band offsets of Si 3 N 4 matrix to Si in comparison with commonly used SiO x /SiO 2 superlattices. However, the annealed SiN x /Si 3 N 4 structures contain an increased number of nanocrystal interface defects, which completely suppress nanocrystal emission spectrum. In this work, we study a novel SiO x N y /Si 3 N 4 hetero multilayer combination, which compromises the major issues of SiO x /SiO 2 and SiN x /Si 3 N 4 superlattices. The annealed SiO x N y /Si 3 N 4 superlattices are investigated by TEM, demonstrating a precise sublayer thicknesses control. The PL spectra of the annealed SiO x N y /Si 3 N 4 superlattices are centered at 845–950 nm with an expected PL peak shift for silicon nanocrystals of different sizes albeit the PL intensity is drastically reduced as compared to SiO 2 separation barriers. The comparison of PL spectra of annealed SiO x N y /Si 3 N 4 superlattice with those of SiO x N y /SiO 2 superlattice enables the analysis of the interface quality of silicon nanocrystals. Using the literature data, the number of the interface defects and their distribution on the nanocrystal facets are estimated. Finally, it is shown that the increase of the Si 3 N 4 barrier thickness leads to the increased energy transfer from the Si nanocrystals into the Si 3 N 4 matrix, which explains an additional drop of the nanocrystal PL intensity.
Print ISSN:
0021-8979
Electronic ISSN:
1089-7550
Topics:
Physics
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