| Popis: |
Solution growth technique (SGT) was successfully used to deposit good quality BeF2 thin films on glass slides at 320K for 3 hours and at pH of 7 – 12. The bath constituents were beryllium nitrate-4-water, and sodium fluoride as starting materials, sodium hydroxide as complexing agent and ethelemediamine tetra-acetate to vary the pH values. Effects of pH and bath constitutions were also investigated. Our numerous investigations reveal that beryllium fluoride thin films were produced only in alkaline medium. The deposited thin films modify the optical properties of the glass substrates at various wavelength regions. Average transmittance (T) values ranges from 0.615 – 0.904, reflectance (R) from 0.052 – 0.175, coefficient of absorption (a) (0.106 – 0.486) x10-4 cm-1 and refractive index (n) from 1.59 – 2.43. Values of solid-state properties such as band gap (Eg) range from 2.22-2.66 eV, electrical conductivity (s) from 0.73 – 1.26) X10-5 (W-cm)-1 and film thickness (t) from 465 - 214Å. Films with refractive index (n) lower than 1.8 have high transmittance (T) and low reflectance (R) while those with refractive index (n) greater than 1.8 have low transmittance (T) and high reflectance (R). The possible applications of the deposited beryllium fluoride (BeF2) thin film in optical, architectural, agricultural and electronics industries were also discussed. (Nigeria Journal of Pure and Applied Physics: 2003 2 (1): 21-27) |
