Incongruent melting phenomenon shows the feasibility of multilevel control using the phase‐change material Ga2Te3Sb5 (Ga‐TS). Electrical results showed that Ga‐TS cells require 25% less RESET current than do GST cells. Meanwhile it possesses a high programming speed, ultralong data retention extrapolated to one million years at 120 °C, and superior thermal properties for phase‐change random‐access‐memory applications.

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Thermal stability is one of the key issues in phase-change memory. We try to tackle it by developing new compositions based on Ga-Te-Sb system. Thermal stability is exemplified using Ga 18 Te 12 Sb 70 which shows crystallization-temperature (T x ) 248 C and activation energy of non-isothermal crystallization 5.9 eV. Films were isothermally soaked at 5 $ 30 C below T x to estimate the failure-time when electrical resistance dropped to a half of the original. Arrhenius plot attained using logarithm failure-time versus reciprocal temperature were extrapolated to the temperature corresponding to 10-year failure (T 10y ) as 183 C. Pre-crystallization structure upon heating to 2 $ 5 C below T x reflects stable amorphous phase of the alloy up to at least 240 C. Memory-cells made of Ga 18 Te 12 Sb 70 can be set-reset at 20 $ 500 ns with electrical currents around 66% those of our Ge 2 Sb 2 Te 5 cells. We suggest that compositions Ga 18-25 Te 8-12 Sb 67-70 are optimal to ensure T x > 240 C, T 10y > 180 C and with low operation-currents. V C 2012 American Institute of Physics.