Abstract:

In this paper, an improved sol-gel method was suggested to obtain high-concentration LiTaO₃ precursor solution for simplified experimental conditions and thicker films, by mixing lithium acetate and tantalum ethoxide in a 1, 2-Propylene glycol solution. Compared to traditional methods, the process was done without weak acidic solution and absolute dry experimental condition. Results of a comparative study of LiTaO₃ thin films derived by the improved sol-gel process and a traditional process using 2-methoxy ethanol as solvent were presented. Nano-crystalline LiTaO₃ films with rhombohedral structures were formed in both methods after annealing at 650℃ for 5 min. The thickness of each LiTaO₃ layer coated onto the substrate increased from 25 nm to 110 nm when 2-methoxy ethanol was replaced by 1, 2-Propylene glycol. LiTaO₃ films with a stronger preferential orientation were obtained in 1, 2-Propylene glycol due to its higher boiling point and slower volatilization rate. On the other hand, the diffraction peak intensity of LiTaO₃ thin films prepared using 1, 2-Propylene glycol was weaker than that of the films prepared using 2-methoxy ethanol due to decreased times of annealing.

Key words: LiTaO₃, Thin film, Sol-gel, Crystallization