Effect of annealing temsperature on some optical properties of LiF thin films


LiF Polycrystalline thin films have been prepared by using thermal evaporation technique on substrates of glass heated at room temperature under vacuum of (10-6mb)and the thickness of films was ( 400 nm ). After that the films were treated thermally at pressure ( 10-3 mb) and a temperature of (323 K ) ,(423 K ) and (473 K) for one hour.The optical measurements which is included the absorbance spectra using UV-VIS spectroscopy in the spectrum range ( 250-850 )nm demonstrated that the values of the absorption coefficient ( α ) was greater than ( 104cm-1) and then ( α ) decreases with increasing of annealing temperature ( Ta ). Moreover, the absorbance spectra were used to find some optical constants such as refractive index ( n ), extinction coefficient ( k ) and dielectric constant ( ε ), and it was found that the optical constants were affected after treating the films thermally.