Oxygen Pressure Influence on Properties of Nanocrystalline LiNbO₃ Films Grown by Laser Ablation

Energy conversion devices draw much attention due to their effective usage of energy and resulting decrease in CO₂ emissions, which slows down the global warming processes. Fabrication of energy conversion devices based on ferroelectric and piezoelectric lead-free films is complicated due to the difficulties associated with insufficient elaboration of growth methods. Most ferroelectric and piezoelectric materials (LiNbO₃, BaTiO₃, etc.) are multi-component oxides, which significantly complicates their integration with micro- and nanoelectronic technology. This paper reports the effect of the oxygen pressure on the properties of nanocrystalline lithium niobate (LiNbO₃) films grown by pulsed laser deposition on SiO₂/Si structures. We theoretically investigated the mechanisms of LiNbO₃ dissociation at various oxygen pressures. The results of x-ray photoelectron spectroscopy study have shown that conditions for the formation of LiNbO₃ films are created only at an oxygen pressure of 1 × 10^-2 Torr. At low residual pressure (1 × 10^-5 Torr), a lack of oxygen in the formed films leads to the formation of niobium oxide (Nb₂O₅) clusters. The presented theoretical and experimental results provide an enhanced understanding of the nanocrystalline LiNbO₃ films growth with target parameters using pulsed laser deposition for the implementation of piezoelectric and photoelectric energy converters.