Effect of Annealing Temperature on the Electric and Dielectric Properties of Se70Te15Bi15Films

Abstract

The effect of annealing at different temperatures between Tg and Tc on the AC conductivity and dielectric properties was studied for Se70Te 15Bi15 films grown by thermal evaporation technique. The films were characterized by X-ray diffraction, differential thermal analysis, and energy dispersive X-ray spectroscopy. X-ray diffraction analysis shows the occurrence of amorphous to polycrystalline transformation for films annealed at annealing temperature Ta ≤ 473 K. AC conductivity σAC(ω) was studied as a function of Ta, frequencies (0.1-100 kHz) and working temperatures (303-393 K). It was found that σAC(ω) obeyed Aω law. According to the values of s and its temperature dependence, the AC conduction mechanism was determined in terms of the correlated barrier hopping and quantum mechanical tunneling models for the as deposited and annealed films, respectively. The DC and AC activation energies were determined as a function of Ta. Values of dielectric constant "1 and dielectric loss "2 were found to increase with increasing Ta. A Debye-like relaxation of dielectric behavior was observed for polycrystalline films, and was found to be a thermally activated process.