Memory elements and cross point switches and arrays of same using nonvolatile nanotube blocks
View Patent ↗Under one aspect, a covered nanotube switch includes: (a) a nanotube element including an unaligned plurality of nanotubes, the nanotube element having a top surface, a bottom surface, and side surfaces; (b) first and second terminals in contact with the nanotube element, wherein the first terminal is disposed on and substantially covers the entire top surface of the nanotube element, and wherein the second terminal contacts at least a portion of the bottom surface of the nanotube element; and (c) control circuitry capable of applying electrical stimulus to the first and second terminals. The nanotube element can switch between a plurality of electronic states in response to a corresponding plurality of electrical stimuli applied by the control circuitry to the first and second terminals. For each different electronic state, the nanotube element provides an electrical pathway of different resistance between the first and second terminals.
1. A nanotube memory device, comprising:
a first and second electrodes;
a switching element having a predetermined pattern comprising a porous network of non-woven nanotubes wherein at least a first nanotube is in electrical communication with the first electrode and at least a second nanotube is in electrical communication with the second electrode, wherein said porous network of non-woven nanotubes is capable of switching between at least two non-volatile resistive states; and
a protective barrier to protect the switching element.
2. The nanotube switch of claim 1 , wherein the protective barrier includes a passivation layer that permeates at least partially into said porous network of nanotubes.
3. The nanotube memory device of claim 2 wherein said passivation layer is an insulator.
4. The nanotube memory device of claim 2 , wherein said passivation layer is a conductor.
5. The nanotube memory device of claim 2 , wherein said passivation layer is a semiconductor.
6. The nanotube memory device of claim 2 , wherein said passivation layer is formed from at least one of SiO 2 , SiN, Al 2 O 3 , and polyimide.
7. The nanotube memory device of claim 2 , wherein said passivation layer is formed from at least one of phosphosilicate glass oxide, planarizing low temperature oxide, sputtered oxide, sputtered nitride, flowfill oxide, chemical vapor deposition of oxide and nitride, atomic layer deposition oxides, and polyvinylidene fluoride.
8. The nanotube memory device of claim 1 , wherein the protective barrier seals the switching element.
9. The nanotube memory device of claim 1 , wherein the protective barrier protects at least a portion of the switching element.
10. The nanotube memory device of claim 1 , wherein the switching element is capable of switching between a plurality of electronic states in response to electrical stimuli applied to the first and second electrodes.