The optical properties of cdte films prepared by flash thermal evaporation method

Abstract EN

The films of CdTe with different thickness (300, 1500, 3000) Ao have been prepared by flash thermal evaporation method onto clean glass substrate.

The effect of thickness on the optical properties of CdTe has been studied.

Its found that they have direct and indirect gaps.

The absorption edge was shift slightly towards higher wavelength.

The value of energy gaps (Eg) for direct transition are decreases with increasing the thickness from (2.5-1.7)eV, and (2.7-2.5) eV for r (= 1 / 2 and 3 / 2) respectively, whereas for indirect transition the value of Eg varies between (2.1-1.3) eV, and (1.5-0.8) eV for r (= 2 and 3) respectively with increasing thicknesses, this behavior due to the decreasing in the amount of free Te with the increase in thicknesses.

Also the absorption coefficient is decreased from (0.9X105, 0.3 X105 and 0.1 X105)cm-1 with increases of thicknesses from (300, 1500, 3000) Ao respectively.

The refractive index (n) and the real part (ε1) of dielectric constant increases with the increasing of thicknesses.

The extinction coefficient and the imaginary part (ε2) of the dielectric constant have similar termed of variation for the absorption coefficient.