Memory switching of ZnGa 2Se 4 thin films as a new material for phase change memories (PCMs)

Abstract

ZnGa 2Se 4 thin films were prepared by using thermal evaporation technique. X-ray diffraction patterns revealed the amorphous nature of the as- deposited films. The dc conductivity was studied as a function of temperature and thickness. The obtained results of dc electrical conductivity showed its semiconductor behavior and can be explained according to Mott and Davis model. The conduction activation energy Δ E σ has one value for each thickness indicating the presence of one conduction mechanism through the studied range of temperature. Both dynamic and static I– V characteristic curves of amorphous ZnGa 2Se 4 thin films for switching and memory behavior have been studied as a function of thickness in the range (136–260 nm) and temperature in the range (305–373 K). I– V characteristic curves showed a memory switching at the threshold point [turnover point (TOP)] from the high resistance state (OFF state) to the low resistance state (ON state). The mean value of threshold voltage V ¯ th increases linearly with increasing the film thickness while decreases exponentially with the increase of temperature. The mean value of the threshold electrical field E ¯ th decreases exponentially with increasing temperature. The values of threshold activation energy ɛ and threshold resistance activation energy Δ E R were calculated. The rapid transitions between the high resistive and conductive states were attributed to an electrothermal model initiated from Joule heating of current channel.