Effect of Thermal Annealing on the Structural, Optical, and Electrical Properties of a-Se Thin Films

Abstract

In this experimental study, Structural, electrical and optical properties of as-grown and annealed films for the amorphous Selenium was carried out. Growing for the samples was done on glass substrates by thermal evaporation technique under pressure range 10-5 - 10-6 Torr at room temperature. The structure of amorphous Selenium thin film was investigated by X-ray diffraction (XRD) for three different annealing temperatures (323, and 363K). The result of the X-ray diffraction studied at 363K indicated the formation of Selenium with Hexagonal Phase. The transmission spectra of annealed and as-deposited films have been carried out for the range UV-Visible transmittance spectrum (wavelength range of 200-1100 nm) at room temperature. Results showed that the absorption coefficient for the previous range was . Results for the optical band gap gave a direct one, within the energy range (2.01-2.11) eV. These experimental values of the optical band gap indicated an inversely proportionated with annealing temperature. Results for both D.C and A.C conductivity for the temperature range 295.5 to 363K showed that both type of conductivity related linearly temperature. Results showed that the A.C. conductivity increases linearly with the frequency at the range ( - ) Hz. Results for the activation energy ( ) shows that it related linearly with the annealing temperature.

Keywords: Amorphous Selenium, Chalcogenide, X-Ray diffraction (XRD).