Formation of beta-Bi₂O₃ and delta-Bi₂O₃ during laser irradiation of Bi films studied in-situ by spatially resolved Raman spectroscopy

Abstract

The formation of different phases of Bi₂O₃ induced by laser irradiation of Bi films has been assessed in situ by micro-Raman spectroscopy as a function of laser wavelength, power density and irradiation time. Raman mapping of the irradiated samples enabled a spatially-resolved study of the distribution of the formed Bi₂O₃ phases. Red laser (633 nm) irradiation was found to induce the appearance of ß- Bi₂O₃, within a certain range of power densities, by diffusion- controlled processes. In contrast, ultraviolet (UV, 325 nm) laser irradiation, above a certain power density threshold, initially induces the formation of both beta and δ- Bi₂O₃ phases. The amount of the produced δ- Bi₂O₃ phase increases by increasing the irradiation time, while that of the beta phase follows the opposite trend. UV laser irradiation seems to be a suitable method to produce room temperature stable δ- Bi₂O₃ patterns on Bi films.