Memory device with active passive layers
View Patent ↗A memory including memory cells having active and passive layers may store multiple information bits. The active layer may include an organic polymer that has a variable resistance based on the movement of charged species (ions or ions and electrons) between the passive layer and the active layer. The passive layer may be a super-ionic material that has high ion and electron mobility. The active layer may be self-assembled from a monomer in a liquid or gas.
1. A reversibly programmable memory comprising at least one memory cell, the at least one memory cell comprising:
a first conductive electrode layer;
a passive layer formed over the first conductive electrode layer, the passive layer comprising a super-ionic material comprising copper sulfide adapted to reversibly donate and accept charged species, the charged species comprising ions or ions and electrons;
an active layer formed over the passive layer, the active layer comprising an organic polymer that has a reversibly variable electrical conductivity upon the introduction and removal of charged species from the passive layer, the electrical conductivity of the organic polymer being variable between three or more states to store multiple information bits, the organic polymer having a relatively lower electrical conductivity when free of charged species and a relatively higher conductivity when charged species are introduced; and
a second conductive electrode layer formed over the active layer;
wherein the passive layer reversibly donates and accepts charged species to and from the active layer when an electrical potential difference is applied between the two conductive electrode layers, and the two conductive electrode layers are used to both program the memory cell to store information and read stored information from the memory cell.
2. The memory of claim 1 , wherein the first conductive electrode layer comprises copper.
3. The memory of claim 1 , wherein the active layer comprises one of polyphenylacetylene and polydiphenylacetylene.
4. The memory of claim 1 , wherein:
the first conductive electrode layer comprises copper, and
the active layer comprises one of polyphenylacetylene and polydiphenylacetylene.
5. The memory of claim 1 , further comprising:
a barrier layer comprising a material that impedes spontaneous movement of charged species between the active layer and the passive layer when an electrical potential difference is not applied between the two conductive electrode layers.
6. The memory of claim 5 , wherein the barrier layer is positioned between the active layer and the passive layer.
7. The memory of claim 1 , wherein the active layer has a thickness from about 50 to about 1000 Angstroms.
8. The memory of claim 1 , wherein the passive layer has a thickness from about 20 to about 100 Angstroms.
9. The memory of claim 1 , wherein the memory cell comprises only one active layer and only one passive layer between the first and second conductive electrode layers.
10. A reversibly programmable memory comprising at least one memory cell, the at least one memory cell comprising:
a first conductive electrode layer;
a passive layer formed over the first conductive electrode layer, the passive layer comprising a superionic material adapted to reversibly donate and accept charged species, the charged species comprising ions or ions and electrons;
an active layer formed over the passive layer, the active layer comprising an organic polymer that has a reversibly variable electrical conductivity upon the introduction and removal of charged species from the passive layer, the electrical conductivity of the organic polymer being variable between three or more states to store multiple information bits, the organic polymer having a relatively lower electrical conductivity when free of charged species and a relatively higher electrical conductivity when charged species are introduced; and
a second conductive electrode layer formed over the active layer;
wherein the passive layer reversibly donates and accepts charged species to and from the active layer when an electrical potential difference is applied between the two conductive electrode layers, and the two conductive electrode layers are used to both program the memory cell to store information and read stored information from the memory cell.
11. The memory of claim 10 , wherein the passive layer comprises copper sulfide.
12. The memory of claim 10 , wherein the first conductive electrode layer comprises copper.
13. The memory of claim 10 , wherein the active layer comprises one of polyphenylacetylene and polydiphenylacetylene.
14. The memory of claim 10 , wherein:
the first conductive electrode layer comprises copper,
the passive layer comprises copper sulfide, and
the active layer comprises one of polyphenylacetylene and polydiphenylacetylene.
15. The memory of claim 10 , further comprising:
a barrier layer comprising a material that impedes spontaneous movement of charged species between the active layer and the passive layer when an electrical potential difference is not applied between the two conductive electrode layers.
16. The memory of claim 15 , wherein the barrier layer is positioned between the active layer and the passive layer.
17. The memory of claim 10 , wherein the active layer has a thickness from about 50 to about 1000 Angstroms.
18. The memory of claim 10 , wherein the passive layer has a thickness from about 20 to about 100 Angstroms.
19. The memory of claim 10 , wherein the memory cell comprises only one active layer and only one passive layer between the first and second conductive electrode layers.
20. The memory of claim 10 , wherein the active layer comprises one of polyaniline, polythiophene, polypyrrole, polystyrene, polyfuran, and polyindole.