Gamma irradiation effect on the optical properties of tellurium dioxide films

Abstract

The gamma radiation induced optical properties of the tellurium dioxide films of thickness 1500 nm, deposited by thermal evaporation in the vacuum, were investigated. The dose dependences of the band gap and other optical parameters have been quantified from the transmittance spectra. The optical band gap decreases with the gamma radiation dose up to 400 Gy from 3.98 to 3.55 eV and increases beyond 400 Gy. Also, the refractive index and extinction coefficient increase appreciably with the gamma radiation dose up to 400 Gy and the two decrease beyond 400 Gy. This behavior of the optical properties is due to generation of the electronic localized states in the band gap and Urbach tail. The change in each of the optical properties due to gamma radiation can be an attractive idea for the TeO2 film as photo-sensitive film-based dosimeter. The proposed material as dosimeter has minimum detectable effect on a dose range of 400 Gy, which is best suited for possible industrial applications such as food processing and sterilization.