Nitrogen-implanted Ge₂Sb₂Te₅film used as multilevel storage media for phase change random access memory

Abstract

Ge2Sb2Te5 films were deposited by RF magnetron sputtering on Si(100)/SiO2 substrates. N+ ion was implanted into Ge2Sb2Te5 films. Two obvious steps were observed in the resistance–temperature curve of the Ge2Sb2Te5-N film with a minor nitrogen implant dose. The two steps may change into one step because the phase transition from FCC to hexagonal structure was suppressed by nitrogen implantation if the nitrogen implant dose is higher than 4.51 × 1016 cm−2. The favourite nitrogen implant dose is about 6.44 × 1015 to 1.92 × 1016 cm−2 in our study. This phenomenon is very important for multilevel storage. Three-level storage with Ge2Sb2Te5-N media for chalcogenide random access memory (C-RAM) can be performed easily, and hence, the capacity of C-RAM will be dramatically increased.