Memory switching and the switching mechanism of Se60Ge40 and Se60Ge36In4 phase change alloys

Abstract Static I − V characteristic curves for memory switching behavior have been studied as a function of film thickness in the range (67–159 nm) and temperature in the range (293–373 K), for amorphous Se 60 Ge 40 and Se 60 Ge 36 In 4 chalcogenide thin films. The films are prepared by thermal evaporation of high purity 5 N materials. X-ray diffraction patterns for the studied materials revealed the amorphicity of the prepared films. The I − V characteristic curves display a memory switching at the threshold point from the state of high resistance (OFF state) to state of the negative differential resistance NDRS (ON state). The average values of threshold voltage ( V t h ) decreased exponentially with increasing temperature and linearly increase with increasing film thickness while they decrease with In addition to Se 60 Ge 40 . The average values of the threshold electric field E t h were calculated and were found to decrease with increasing temperature for both the studied compositions. The electrical conduction activation energies Δ E σ for Se 60 Ge 40 and Se 60 Ge 36 In 4 were calculated and found to be 0.269  eV and 0.19 eV respectively. The threshold voltage activation energy Δ e t h and the ratio ( Δ e t h / Δ E σ ) were calculated for Se 60 Ge 40 and Se 60 Ge 36 In 4 and the values of ( Δ e t h / Δ E σ ) were found to be 0.327 and 0.52 respectively, which supports the electrothermal model. The transition between the Off-State and On-States was attributed to the Joule heating of current channel according to the electrothermal model. The effect of In addition to SeGe on the studied parameters was discussed.