Comparison of Crystal and Phonon Structures for Polycrystalline BaSi₂ Films Grown by SPE Method on Si(111) Substrate

Abstract:

The search for inexpensive and efficient methods of forming thin BaSi₂ films as a promising material for photovoltaic is an actual task. The co-deposition of Ba and Si atoms with alloy thickness of 100-120 nm on the silicon substrate at room temperature with following annealing (SPE method) was proposed. Ba-Si alloy compounds then were thermally annealed at different temperatures and three samples were formed: #1 at T = 600 ° C, #2 at T = 700 ° C and #3 at T = 800 ° C. Polycrystalline films with an orthorhombic BaSi₂ structure were formed by XRD, UV-VIS, FIR and Raman spectroscopies data. BaSi₂ grains in samples #1 and #2 have sizes 62-64 nm and 86 nm in the sample #3 from XRD data calculations by Scherrer formula. Proposed growth method resulted to strong compression of the BaSi₂ unit cell volume on 1.78 – 2.70%. The strongest compression was observed after annealing at 800 °C, which was accompanied by desorption of a noticeable amount of barium and a strong decrease in the film thickness in the sample #3. The formation of nanosize Si clusters was confirmed by Raman data for samples #2 and #3, but they did not observed in the sample #3. So, the film, formed at 800 °C, is the most qualitative in terms of structure and single-phase BaSi₂, but with strong decrease of initial Ba-Si alloy thickness due to Ba desorption.

• Periodical: Defect and Diffusion Forum (Volume 386)
• Pages: 48-54
• DOI: https://doi.org/10.4028/www.scientific.net/DDF.386.48
• Online since: September 2018
• Authors: Nikolay G. Galkin, Dmitrii Vladimirovich Fomin, Victor Leonidovich Dubov, Konstantin Nickolaevich Galkin, Sergey Anatolyevich Pyachin, Alexander Burkov
• Keywords: Barium Silicide, Crystal, Film, Lattice Compression, Phonon Structure, Solid Phase Growth

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