SWITCHING PHENOMENON IN EVAPORATED SE-GE-AS THIN-FILMS OF AMORPHOUS-CHALCOGENIDE GLASS

Both dynamic and static I-V characteristic curves of amorphous thin films of Se75Ge25-xAsx (5 less-than-or-equal-to x less-than-or-equal-to 20) for switching and memory behaviour have been studied. The films were prepared by thermal evaporation of high purity (99.999%) material. X-ray diffraction patterns revealed the formation of amorphous films. The electrical measurements are made at room temperature and at elevated temperatures up to the glass transition temperature (T(g) approximately 418 K). The conduction activation energy, E(sigma) is determined. The threshold voltage, V(th) is determined. It is found that V(th) increases linearly with the film thickness and decreases with As content. Moreover, V(th)BAR decreases exponentially with temperature. The rapid transition between the highly resistive and conductive states is attributed to an electrothermal mechanism from the Joule heating of a current channel.