Effect of Gamma Irradiation on Electrical and Photoelectrical Properties of CdFeTe Thin Films

Öz

Cd_1−xFe_xTe solid solutions (purity 99.999%) was used to obtain thin films by the Molecular Beam Condensation method in a vacuum of 10^-4Pa at substrate temperature T_sub=670 K and source temperature T_sour=1100 K. The condensation rate was υ = 18-20Ả / s and film thickness was d = 2 μm.

      The crystal structure and surface morphology of thin films were studied by XRD method on Bruker D8 Advance XRD and SEM scanning electron microscope on Carl Zeiss Sigma VP.

      VAC of Cd_1−xFe_xTe, x=0.08 thin films and the effect of γ-irradiation on them were studied at T=300K temperature. VAX measurements were performed at D_γ ≤ 1kGy γ-irradiation doze. The observed dependence shows that when Cd_1−xFe_xTe (x=0.08) thin films are irradiated with small doses, deep levels are formed in the forbidden zone, and these levels are occupied by a part of electrons, the remaining electrons participate in conduction and cause an increase in current. When samples are irradiated with a dose of D_γ = 500 Gy, decrease in conductivity are observed, which indicates an increase in the concentration of defects. At doses D_γ ≥ 1kGy, conductivity decreases, which explained by an increase in the concentration of defects and thus a violation of the crystal structure.

       Illumination of semiconductors leads to optical filling of local levels, which differs significantly from that in the dark. The effect of γ-irradiation on the photoconductivity can be explained by the formation of various types of defects in them. Spectral characteristics of photoconductivity shows that spectral range covers the wavelength range λ = 400 nm-1500 nm. There is a broad band in the PC spectrum, the width of the forbidden zone calculated from the PC maximum (λ = 800 nm) E_g= 1.55 eV at T = 300 K. The effect of γ-irradiation on spectral characteristics shows that Cd_1−xFe_xTe, x=0.08 thin films are sensitive to illumination and γ –irradiation.