Chalcogenide devices exhibiting stable operation from the as-fabricated state
View Patent ↗A chalcogenide material and chalcogenide memory device having less stringent requirements for formation, improved thermal stability and/or faster operation. The chalcogenide materials include materials comprising Ge, Sb and Te in which the Ge and/or Te content is lean relative to the commonly used Ge 2 Sb 2 Te 5 chalcogenide composition. Electrical devices containing the instant chalcogenide materials show a rapid convergence of the set resistance during cycles of setting and resetting the device from its as-fabricated state, thus leading to a reduced or eliminated need to subject the device to post-fabrication electrical formation prior to end-use operation. Improved thermal stability is manifested in terms of prolonged stability of the resistance of the device at elevated temperatures, which leads to an inhibition of thermally induced setting of the reset state in the device. Significant improvements in the 10 year data retention temperature are demonstrated. Faster device operation is achieved through an increased speed of crystallization, which acts to shorten the time required to transform the chalcogenide material from its reset state to its set state in an electrical memory device.
1. An electrical device comprising
a chalcogenide material, said chalcogenide material comprising Ge, Sb, and Te; said Ge having an atomic concentration between 11% and 18%, said Sb having an atomic concentration between 37% and 61.1%, and said Te having an atomic concentration between 27% and 45%;
a first electrode in electrical communication with said chalcogenide material; and
a second electrode in electrical communication with said chalcogenide material, said device having: a virgin state, a first set state formed by setting said virgin state, a first reset state formed by resetting said first set state, a second set state formed by setting said first reset state, a second reset state formed by resetting said second set state, and a third set state formed by setting said second reset state,
wherein the resistance of said first set state differs from the resistance of said virgin state by less than 50%.
2. The electrical device of claim 1 , wherein the resistance of said first set state differs from the resistance of said virgin state by less than 25%.
3. The electrical device of claim 1 , wherein the resistance of said first set state differs from the resistance of said virgin state by less than 15%.
4. The electrical device of claim 1 , wherein the resistance of said second set state differs from the resistance of said first set state by less than 25%.
5. The electrical device of claim 4 , wherein the resistance of said third set state differs from the resistance of said second set state by less than 15%.
6. The electrical device of claim 1 , wherein the resistance of said second set state differs from the resistance of said first set state by less than 15%.
7. The electrical device of claim 1 , wherein the atomic concentration of said Ge is between 15% and 18%.
8. The electrical device of claim 1 , wherein the atomic concentration of said Sb is between 37% and 46%.
9. The electrical device of claim 1 , wherein the atomic concentration of said Te is between 38% and 45%.