Berlin 2015 – wissenschaftliches Programm
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DS: Fachverband Dünne Schichten
DS 36: Poster Session I
DS 36.44: Poster
Donnerstag, 19. März 2015, 09:30–12:00, Poster A
Silicon nanocrystals of uncontrollable sizes formed in SiNx/SiO2 hetero-superlattices — •Anastasiya Zelenina1, Andrey Sarikov2, Denis Zhigunov3, and Margit Zacharias1 — 1Georges-Koehler-Allee 103, Freiburg 79110, Germany — 245 Nauki Avenue, Kiev 03028, Ukraine — 3Leninskie Gory 1, Moscow 119991, Russia
SiNx/SiO2 hetero-superlattices with SiNx sublayer thickness of 3 nm and SiO2 barrier thicknesses of 3 and 10 nm were prepared by PECVD. In contrast to the number of the publications based on the preparation of silicon nanocrystals (Si NCs) by size-controlled superlattice approach, high-temperature annealing at 1200°C leaded to the formation of silicon nanocrystals (Si NCs) with various sizes in the range of 2.5 - 12.5 nm embedded in mainly oxynitride matrix. The multilayer structure was completely destroyed after the high-temperature annealing and no periodicity was observed for the sample with 3 nm SiO2 barrier. The increasing of SiO2 barrier thickness up to 10 nm did not change the results: the multilayer structure was destroyed and Si NCs of uncontrollable sizes were formed. It is worth noting that according to the TEM images the as-prepared structures were well-organized and had smooth sublayer interfaces. To investigate this unusual behavior, the phase separation and PL were investigated at different temperatures of annealing. Based on the experimental results, we conclude that the loss of size control occurs due to the oxygen migration from SiO2 barriers into SiNx sublayers. Thermodynamic reasons are assumed to be responsible for this process.