Devices having vertically-disposed nanofabric articles and methods of making the same
Electro-mechanical switches and memory cells using vertically-oriented nanofabric articles and methods of making the same. Under one aspect, a nanotube device includes a substantially horizontal substrate having a vertically oriented feature; and a nanotube film substantially conforming to a horizontal feature of the substrate and also to at least the vertically oriented feature. Under another aspect, an electromechanical device includes a structure having a major horizontal surface and a channel formed therein, the channel having first and second wall electrodes defining at least a portion of first and second vertical walls of the channel; first and second nanotube articles vertically suspended in the channel and in spaced relation to a corresponding first and second wall electrode, and electromechanically deflectable in a horizontal direction toward or away from the corresponding first and second wall electrode in response to electrical stimulation.
1. An nanotube switching device, comprising:
a structure having a major horizontal surface and a channel formed therein,
the channel having a vertical wall and first and second electrodes each forming a portion of the vertical wall;
a nanotube article vertically disposed in the channel and in contact with said first and second electrodes, the nanotube article responsive to electrical stimulus to form and unform an electrically conductive pathway between said first and second electrodes.
2. The nanotube switching device of claim 1 , wherein forming and unforming an electrically conductive pathway corresponds to switching between a first and a second resistance state between the first and second electrodes.
3. The nanotube switching device of claim 1 , wherein the nanotube article comprises a portion of a nanotube fabric.
4. The nanotube switching device of claim 3 , wherein the nanotube fabric is conformally disposed on the vertical wall of the channel.
5. The nanotube switching device of claim 1 , wherein the first electrode comprises a conductive material disposed in and forming a bottom surface of the channel.
6. The nanotube switching device of claim 5 , wherein the second electrode comprises a conductive material forming an upper portion of the vertical wall.
7. The nanotube switching device of claim 6 , wherein the structure comprises a dielectric material and wherein the dielectric layer is interposed between the first electrode and the second electrode.
8. The nanotube switching device of claim 1 , wherein the nanotube article nonvolatilely forms and unforms the electrically conductive pathway.
9. The nanotube switching device of claim 1 , wherein the vertically disposed nanotube article comprises a pinned section disposed over the second electrode and pinned by an insulating layer.
10. A memory array comprising a plurality of nanotube switching devices, each device having:
a structure having a vertical wall and first and second electrodes each forming a portion of the vertical wall;
a nanotube article vertically disposed in contact with said first and second electrodes, the nanotube article responsive to electrical stimulus to form and unform an electrically conductive pathway between said first and second electrodes;
wherein at least two of the plurality of nanotube switching devices are vertically stacked.
11. The memory array of claim 10 , wherein forming and unforming an electrically conductive pathway corresponds to switching between a first and a second resistance state between the first and second electrodes.
12. The memory array of claim 10 , wherein the nanotube article comprises a portion of a nanotube fabric.
13. The memory array of claim 12 , wherein the nanotube fabric is conformally disposed on the vertical wall of the structure.
14. The memory array of claim 10 , wherein the nanotube article volatilely forms and unforms the electrically conductive pathway.
15. The memory array of claim 10 , wherein the nanotube article nonvolatilely forms and unforms the electrically conductive pathway.
16. The memory array of claim 15 , further comprising sensing circuitry in electrical communication with the first and second electrodes of each nanotube switching device for sensing a resistance state between the first and second electrodes, wherein the resistance state is substantially undisturbed by the sensing circuitry sensing the resistance state.
17. The memory array of claim 10 , wherein for at least two vertically stacked nanotube switching devices, the first nanotube switching device and the second nanotube switching device share one of the first and second electrodes.
18. The memory array of claim 10 , wherein for each nanotube switching device, the first electrode comprises a layer of conductive material having a surface forming a bottom portion of the vertical wall.
19. The memory array of claim 18 , wherein the second electrode comprises a layer of conductive material having a surface forming an upper portion of the vertical wall.
20. The memory array of claim 19 , wherein the structure comprises a dielectric material and wherein the dielectric layer is interposed between the first electrode and the second electrode.
21. The memory array of claim 20 , wherein the nanotube article is printed over an upper surface of the second electrode, the vertical wall, and an upper surface of the first electrode.
22. The memory array of claim 20 , wherein the nanotube article is conformally disposed over a surface of the dielectric layer, and wherein the portion of the nanotube article in contact with the dielectric layer switches between a first and a second resistance state to form and unform the electrically conductive pathway.
23. A nanotube switching device comprising:
a substrate having a major surface defining a horizontal orientation;
a nanotube article having a plurality of nanotubes, wherein the article is oriented substantially vertically, wherein the article is in electrical contact with a first and second electrode at either end of said article, and wherein said article is switchable between two informational states.
24. The nanotube switching device of claim 23 , wherein the first electrode comprises a bottom electrode disposed on the substrate and wherein the second electrode comprises a top electrode disposed over an upper surface of the nanotube article.
25. The nanotube switching device of claim 23 , wherein the nanotube article comprises a plurality of non-woven nanotubes, providing a plurality of electrically conductive pathways between the first and second electrodes.