Silicon (Si) nanopartcles (NPs) embedded in the insulating or semiconducting matrices has attracted much interest for the third generation of photovoltaics, so called “all-Si” tandem solar cells. In this work, the amorphous Si rich silicon carbide (SRSC) absorber layers with 30% carbon content were deposited using plasma enhanced chemical vapour deposition (PECVD) on quartz substrate at 500 ˚C, and then the SRSC films were annealed at 1100 ˚C in nitrogen for 1 hour 1. The thermal treatment leads to the SRSC films spinodally decomposed into a Si-SiC nanocomposite. The nanostructures of the phase separated Si and SiC presented in the 15 minutes and 1 hour annealed SRSC films were investigated by two dimensional (2D) energy-filtered transmission electron microscopy (EFTEM). After the thermal treatment, the coexistence of crystalline Si and SiC nanoparticles (NPs) were observed from the high resolution TEM (HRTEM) images and verified by the selected area diffraction (SAD) patterns. After 1 hour annealing, neither Si nor SiC phases are complelely crystallized, the detailed morphologies of Si and SiC nanostructures were studied by electron tomography. For the first time, we make use of EFTEM spectra-imaging (SI) dataset to reveal the three dimensional distributions of Si, a-SiC and c-SiC in sub-volumes. In particular, to obtain more detailed and quantitative information, we have fitted the plasmon spectra with reference plasmon peaks. This enables us to not only to get a quantitative 3D image of all components involved in the materials system in the final tomogram, but also to obtain information about hitherto undetected phases in this system. In such energy resolved plasmon tomograms, the 3D shape of a thin amorphous SiC layer (1) was observed at interface between the crystalline Si network like structure and crystalline SiC NPs. The appearance of the a-SiC interfacial layer is expected from nucleation theory.
The authors ackonwledge the support from the EU funded FP7 Project SNAPSUN, the Knut and Alice Wallenberg Foundation and the Swedish Science Council.
1. Perraud, S. et al. Silicon nanocrystals: Novel synthesis routes for photovoltaic applications. Phys. Status Solidi a-Applications Mater. Sci. 210, 649–657 (2013).
To cite this abstract:Ling Xie, Karol Jarolimek, Rene Van Swaaij, Klaus Leifer; Three dimesional nano- and interfacial structures in the Si rich SiC systems analysed by spectroscopic electron tomography. The 16th European Microscopy Congress, Lyon, France. https://emc-proceedings.com/abstract/three-dimesional-nano-and-interfacial-structures-in-the-si-rich-sic-systems-analysed-by-spectroscopic-electron-tomography/. Accessed: April 3, 2020
EMC Abstracts - https://emc-proceedings.com/abstract/three-dimesional-nano-and-interfacial-structures-in-the-si-rich-sic-systems-analysed-by-spectroscopic-electron-tomography/