DC electrical conductivity and switching phenomena of amorphous Te81Ge15Bi4 films

Highlights: • Conduction in Te₈₁Ge₁₅Bi₄ occurs by hopping mechanism and is thermally activated. • I–V curves for Te₈₁Ge₁₅Bi₄ films have the behaviour of memory switches. • $V_{th}$ increases linearly with film thickness and decreases with temperature. • Memory switching in Te₈₁Ge₁₅Bi₄ follows the electrothermal model with Joule heating. Thin films of Te₈₁Ge₁₅Bi₄ were prepared from its bulk glass by thermal evaporation method. Amorphous structure of the prepared films was examined by X-ray diffraction (XRD). Differential thermal analysis (DTA) was carried out to obtain the glass transition temperature $T_g$. DC conductivity ${\sigma }_{dc}$ was studied as a function of temperature below $T_g$ in the range (303–393 K) and in thickness range (143–721 nm). The results obtained are based on the model of Mott and Davis. The obtained films were found to exhibit memory type of electrical switching behaviour. The threshold switching voltage $V_{th}$ is found to be reduced exponentially with temperature and enhanced with the thickness of the film in the considered range. The obtained results of the switching behaviour are interpreted according to the electrothermal model motivated by Joule heating.