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



Cd1−xFexTe 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 Tsub=670 K and source temperature Tsour=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 Cd1−xFexTe, x=0.08 thin films and the effect of γ-irradiation on them were studied at T=300K temperature. VAX measurements were performed at Dγ ≤ 1kGy γ-irradiation doze. The observed dependence shows that when Cd1−xFexTe (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 Dγ = 500 Gy, decrease in conductivity are observed, which indicates an increase in the concentration of defects. At doses Dγ ≥ 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) Eg= 1.55 eV at T = 300 K. The effect of γ-irradiation on spectral characteristics shows that Cd1−xFexTe, x=0.08 thin films are sensitive to illumination and γ –irradiation.

Anahtar Kelimeler

Semimagnetic, Semiconductor, Thin film, γ-irradiation, VAX, Photoconductivity, XRD, SEM

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