Probing the growth window of LaVO3 perovskites thin films elaborated using magnetron co-sputtering
Résumé
LaVO3 is a promising material for tuning and improving solar cell performances when modifying the La/V stoichiometry. However, the production of LaVO3 thin films still requires a complex process (MBE, PLD), and the growth window of LaVO3 structure in terms of La/V ratio, already defined in the literature using hybrid-MBE is not determined for elaboration based on magnetron co-sputtering of both vanadium and lanthanum targets followed by an external reducing annealing that we use here. La/V ratio has been varied from 0.52 to 1.68 by changing the power applied to the vanadium target in order to synthesize films with different La/V ratios. The off-stoichiometry growth window has been investigated by complementary methods (XRD, XPS, FTIR and TEM). X-ray diffraction highlights the LaVO3 structure for all the films. For La-rich samples (La/V ratio andgt;1.2), the formation of lanthanum oxide La2O3 is observed at the top surface and interface with the substrate, according to XPS, FTIR and TEM investigations. On the other hand, for V-rich samples, only a slight modification of the structure is observed below the La/V ratio = 0.6; with the presence of a new IR vibration mode corresponding to a small contribution of vanadium oxide(s) present in volume. Our study allows a better definition of the LaVO3 growth window in terms of La/V ratio, estimated from 0.6 to 1.2. © 2019
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