Comparison study of microstructure, chemical composition and optical properties between resistive heating and electron beam evaporated LaF3 thin films

LaF3 thin films were deposited by electron beam (EB) and resistive heating (RH) evaporation, respectively. Properties such as microstructure, chemical composition, surface morphology and optical constants of the LaF3 thin films were characterized by measurements of X-ray diffraction, X-ray photoelectron spectroscopy, atomic force microscopy and spectrophotometer, then comparison was made between this two deposition methods. It's found that the microstructure properties of the LaF3 films deposited by these two methods were different, and slight content of oxyfluoride films was formed during deposition according to the result of chemical composition analysis. The microstructure of LaF3 bulk materials after interaction with electron beam and resistive heating was also characterized to analyze how the two deposition processes affect the formation of LaF3 thin films and their microstructure properties. When it was for the laser resistance of the films, although the EB evaporated LaF3 thin films occupied lower absorption and optical loss than those of the RH films, they showed slightly smaller laser induced damage thresholds at 355 nm, which was thought to be related to their much more rougher surface and higher tensile stress.