Correlative raman and SEM-EDX investigation of sputtered chalcogenide perovskite BaZrS 3 Hasan Arif Yetkin 1 , Comparotto C. 2 , Scragg J. 2 , Guennou M. 1 , Dale, P. 1 1 University of Luxembourg, Luxembourg, 2 Uppsala University, Sweden High band gap halide organic inorganic perovskite solar cells have made remarkable progress in the last years and have achieved efficiencies similar to that of silicon solar cells. This progress stimulates the large-scale research and production of halide perovskite – silicon tandem solar cells, overcoming the Shockley-Queisser limit for single junction solar cells. However, serious concerns about the toxicity and stability issues inherent to halide perovskites are rising in the photovoltaic community. Taking advantage of the similar crystal structures of halide perovskites, chalcogenide perovskites are attracting a lot of attention since they are reported to be stable and consist of non-toxic earth abundant elements. Of these, BaZrS 3 with a suitable band gap range is of paramount interest for the application of tandem solar cells. When starting to research a new material it is imperative to investigate its phase purity to ensure sound conclusions about its opto-electronic properties. Here we report a correlative multi-wavelength Raman and SEM-EDX investigation on a BaZrS 3 library sample deposited on a Si-wafer in order to differentiate and identify secondary phases, if any. The BaZrS 3 thin film was synthesized by reactively co-sputtering BaS and Zr in H 2 S and post annealing at 900 °C [1]. To probe identical locations with both characterization techniques, some fiducial markers are scratched into the sample. Raman spectra were measured with 532, 633 and 785 nm irradiation. It was found that 633 nm irradiation produced the best signal to noise ratio of all the excitation sources. The majority of the probed areas exhibit a Raman spectrum similar to that reported in the literature. Some of the measured Raman spectra of BaZrS 3 thin films exhibit slight peak shift, hinging on the location. These shifts are most likely stemming from the strain in the thin film, since there are a lot of pinholes and cracks caused by the synthesis procedure. However, SEM-EDX analysis on the identical location show inconsistency with the Raman measurements in terms of the stoichiometry of the BaZrS 3 thin film, revealing the moderate amount of oxygen and S off-stoichiometry. References 1. Comparotto, Corrado, et al. "Chalcogenide Perovskite BaZrS 3 : Thin Film Growth by Sputtering and Rapid Thermal Processing." ACS Applied Energy Materials 3.3 (2020): 2762-2770.
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