Pulse voltage induced phase change characteristics of the ZnxSbyTez phase-change prototype device

Abstract

ZnxSbyTez thin films are deposited on quartz or glass substrates by the electron beam evaporation technique in an ultra-high vacuum. A prototype phase change memory device using the ZST (ZnxSbyTez) thin film is fabricated. The current–voltage test results of the device show the threshold voltage of ZST531 (Zn5.18Sb3.75Te1.10 at.%) is 2.4 V, which is similar to that of the device based on pure Ge2Sb2Te5. It is shown that the phase-change device with the ZST film is able to perform several reading and writing cycles and the off/on resistance ratio is nearly 10 under pulse voltage. The switching performance of the device is also investigated. Most importantly, the results of the in situ resistance measurements show that the increase of crystallization temperature and the higher 10-year data retention temperature are as high as 300 °C and 191 °C, respectively. This indicates that the ZnxSbyTez material is quite stable, and thus appropriate for use in phase-change memory.

Characterization of undoped and N–Ti codoped Zn5Sb3Te chalcogenides

“…However, Sb 2 Te 3 , Ge 2 Sb 2 Te 5 , and GeTe chalcogenides have low crystallization temperatures of 75 °C, 150 °C, and 220 °C, respectively. [21][22][23][24][25] This often indicates a low thermal stability of the amorphous phase. The activation energy of Ge 2 Sb 2 Te 5 is 2.98 eV, and the 10 year data retention temperature is as low as 89 °C.…”

“…33) In previous studies, researchers focused only on improving thermal stability by doping Zn or other elements into Sb 2 Te and Sb 3 Te. 24,33) There is still a lack of overall improvement of both thermal stability and surface roughness.…”