Switching Phenomena of Amorphous Ga₅Ge₁₅Te₈₀ Chalcogenide Thin Films for Phase-Change Memories

Abstract

a-Ga₅Ge₁₅Te₈₀ chalcogenide thin films have been prepared using the e-beam evaporation technique. The amorphous structure of the deposited films has been confirmed using x-ray diffraction and transmission electron microscopy techniques. The direct-current (DC) electrical conductivity and switching phenomena were studied for different Ga₅Ge₁₅Te₈₀ film thicknesses at different temperatures. The determined activation energy ΔE _σ was found to be independent of the film thickness (268 nm to 562 nm) in the measured temperature range (300 K to 380 K). I–V characteristic curves of the amorphous Ga₅Ge₁₅Te₈₀ films show a memory switching behavior. The mean value of the threshold voltage $\bar{V}_{\rm{th}}$ increases linearly with increasing film thickness, and decreases exponentially with increasing temperature. The values of switching activation energy ε were calculated for different film thicknesses. The obtained results were explained on the basis of a thermal model for initiating the switching process, which indicates the possibility of using the composition for phase-change memory.