Swift Heavy Ions (SHI) Induced Grain Size Reduction in Fluoride Thin Films

摘要: In present paper, effect of swift heavy ions (SHI) irradiation has been studied on the grain sizes of 100 nm CaF 2 and 150 nm BaF 2 thin films for fluences in the range of 5× 10 11-2× 10 13 ions/cm 2. The thin films were grown on Si substrate using electron beam evaporation method at room temperature. All the irradiation was performed using 100 MeV Au+ 8 ions at normal incidence, scanning entire area (1cm× 1cm) of the samples.From glancing angle X-ray diffraction (GAXRD) results of irradiated and pristine CaF 2 and BaF 2 samples (Fig. 1), the broadening and shifting of the peaks were observed due to SHI irradiation. The broadening of the peak indicates the reduction in the grain size due to ion irradiation. The grain size decreases from about 29 nm for the pristine samples to a minimum of about 15 nm for CaF 2 and from 38 nm for pristine sample to 22 nm for BaF 2 for high fluence irradiation and remains almost unaltered thereafter depending on the growth and irradiation parameters, as shown in Fig. 2.