radiation (40 kV, 30 mA) in steps of 0.01 at a scanning rate
of 7/min from 20 to 70 under the atmospheric pressure.
The optical constants and thicknesses of the films were characterized
using Variable Angle Spectroscopic Ellipsometer
(VASE) (J.A. Woollam Co., Inc) at wavelengths ranging from
300 nm to 800 nm at an angle of 70. Absorbance, transmittance
was recorded using UV–vis spectrophotometer
(Shimadzu) along a range of wavelengths from 200 nm to
800 nm