Crystallization in Er/Yb:BaTiO₃ Perovskite Induced by fs-Laser Pulses

Perovskite films have been attracting tremendous attention as promising candidates for applications in photonics and optoelectronics, including light-emitting diodes, photo-detectors, energy-harvesting devices, etc. Such applications are sensitive to changes in crystallization, size, and distribution of grains in the perovskite films. Hence, studies have been carried out to improve the quality of thin films and investigate the effect of sintering on the crystalline phase of the sample. Even though several sintering methods have been developed, fs-laser sintering has appeared as a versatile and rapid option, offering precise and localized energy distribution to the sample. The fs-laser sintering can produce highly crystalline devices with complex structures, although it depends on the processing parameters.<br/>This study demonstrates the crystallization of amorphous Er³⁺/Yb³⁺:BaTiO₃ (BTEY) thin film upon fs-laser processing at 1030 nm. The threshold fluence to achieve laser processing was determined as 1.1 J/cm² at 1 kHz, as well as the irradiation conditions for crystallization. Raman spectroscopy confirmed crystallization when irradiation was carried out at a 1 kHz repetition rate. Also, an increase in the sample emission was observed in the crystallized regions and on the surface potential. Such results provide insights into using fs-laser pulses for the crystallization of BTEY, which is relevant for device applications.