Impact of material composition on the write performance of phase-change memory devices

The phase-change memory (PCM) technology represents one of the most attractive concepts for next generation data storage. PCM operation is based on the particular properties of a chalcogenide alloy, the ternary compound Ge
₂
Sb
₂
Te
₅
, which is able to perform fast and reversible transitions between a crystalline, high-conductive phase and an amorphous, low-conductive one, thus enabling the binary data storage. Although the ternary alloy Ge
₂
Sb
₂
Te
₅
is the best recognised solution to meet the device reliability and performance specifications, other alloys are being studied within the GeSbT e ternary compound system in order to investigate and to enlarge the possible spectrum of PCM applications. This work focuses both on the program parameters and on the write performances of a Sb-rich GST composition, suggesting a change in the physical properties of the PCM material and a transition from nucleation to growth-dominated crystallization mechanism, both controlled by the material composition engineering. This enables new challenging performance parameters.