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

Abstract

The e ect of annealing at di erent temperatures between Tg and Tc on the AC conductivity and dielectric properties was studied for Se70Te15Bi15 lms grown by thermal evaporation technique. The lms were characterized by X-ray di raction, di erential thermal analysis, and energy dispersive X-ray spectroscopy. X-ray di raction analysis shows the occurrence of amorphous to polycrystalline transformation for lms 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 s 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 lms, respectively. The DC and AC activation energies were determined as a function of Ta. Values of dielectric constant e1 and dielectric loss e2 were found to increase with increasing Ta. A Debye-like relaxation of dielectric behavior was observed for polycrystalline lms, and was found to be a thermally activated process.