Preparation and characterization of MgF₂ thin film by a trifluoroacetic acid method

The preparation of magnesium fluoride (MgF₂) thin films on silica glass substrates was studied by a trifluoroacetic acid (TFA) method using trifluoroacetic acid as a fluorine source. The coating solution was prepared by stirring a mixture of magnesium ethoxide, isopropanol and TFA. MgF₂ thin films were obtained by heat-treatment of the spin-coated films below 500°C in air. Higher optical transmittance of the films was observed as compared to the substrates. Field emission scanning electron microscope (FE-SEM) observation revealed a particle size of less than 50 nm in the films. The formation process of MgF₂ from trifluoroacetate gels was discussed according to the results of the thermal analysis of the gel.