Switching materials comprising mixed nanoscopic particles and carbon nanotubes and method of making and using the same

• US 8,586,424 B2
• Filed: 03/29/2011
• Issued: 11/19/2013
• Est. Priority Date: 11/19/2008
• Status: Active Grant

• Current Assignee: ZEON Corporation
• Original Assignee: Nantero Incorporated
• Inventors: Ghenciu, Eliodor G., Rueckes, Thomas, Yao, Thierry, Kocab, Thomas
• Primary Examiner(s): Stark, Jarrett
• Assistant Examiner(s): TOBERGTE, NICHOLAS J
• Application Number:
  US13/074,792
• Publication Number:
  US 20110183489A1
• Time in Patent Office: 966 Days
• Field of Search: 257/109, 438/139
• US Class Current: 438/139
• CPC Class Codes: B82Y 10/00 Nanotechnology for information processing, storage or transmission, e.g. quantum computing or single electron logic
• CPC Class Codes: G11C 13/0069 Writing or programming circuits or methods
• CPC Class Codes: G11C 13/025 using fullerenes, e.g. C60, or nanotubes, e.g. carbon or silicon nanotubes
• CPC Class Codes: G11C 2013/009 Write using potential difference applied between cell electrodes
• CPC Class Codes: G11C 2213/79 Array wherein the access device being a transistor
• CPC Class Codes: H10B 63/30 comprising selection components having three or more electrodes, e.g. transistors
• CPC Class Codes: H10K 10/50 Bistable switching devices
• CPC Class Codes: H10K 19/202 Integrated devices comprising a common active layer
• CPC Class Codes: H10K 71/12 using liquid deposition, e.g. spin coating
• CPC Class Codes: H10K 85/20 Carbon compounds, e.g. carbon nanotubes or fullerenes
• CPC Class Codes: H10K 85/221 Carbon nanotubes
• CPC Class Codes: H10N 70/021 Formation of the switching material, e.g. layer deposition
• CPC Class Codes: H10N 70/20 Multistable switching devices, e.g. memristors
• CPC Class Codes: H10N 70/231 based on solid-state phase change, e.g. between amorphous and crystalline phases, Ovshinsky effect
• CPC Class Codes: H10N 70/826 adapted for essentially vertical current flow, e.g. sandwich or pillar type devices
• CPC Class Codes: H10N 70/8845 Carbon or carbides
• CPC Class Codes: Y10T 428/25 Web or sheet containing structurally defined element or component and including a second component containing structurally defined particles

Abstract

An improved switching material for forming a composite article over a substrate is disclosed. A first volume of nanotubes is combined with a second volume of nanoscopic particles in a predefined ration relative to the first volume of nanotubes to form a mixture. This mixture can then be deposited over a substrate as a relatively thick composite article via a spin coating process. The composite article may possess improved switching properties over that of a nanotube-only switching article. A method for forming substantially uniform nanoscopic particles of carbon, which contains one or more allotropes of carbon, is also disclosed.

Claims

1. A method for forming a composite nanofabric article over a substrate, said method comprising:

combining a first volume of nanotubes with a second volume of nanoscopic particles at a predefined ratio relative to said first volume of nanotubes to form a mixture; and

depositing said mixture over said substrate to form the composite nanofabric article;

wherein said second volume of nanoscopic particles includes at least one of silicon nitride particles and multi-walled nanotubes.

2. The method of claim 1, wherein the nanotubes comprising said first volume are substantially all carbon nanotubes.

3. The method of claim 1 wherein said second volume of nanoscopic particles includes nanoscopic particles containing at least one allotrope of carbon.

4. The method of claim 1, wherein said second volume of nanoscopic particles includes silicon oxide particles.

5. The method of claim 1, wherein substantially all of said nanoscopic particles within said second volume fall within a predetermined volume tolerance.

6. The method of claim 1, wherein at least one of the magnitude of said first volume of nanotubes and the magnitude of said second volume of nanoscopic particles is selected to realize a desired volume density of nanotubes within said composite article.

7. The method of claim 1, wherein the mixture is a homogeneous mixture.

8. The method of claim 1, wherein the mixture is a heterogeneous mixture.

9. The method of claim 1, wherein the composite nanofabric article has less than about 10¹¹ metal atoms/cm.

10. The method of claim 1, wherein said depositing said mixture over said substrate is performed via a spin coat process.

11. A method of forming substantially uniform nanoscopic particles of carbon particles from a volume of carbon black material, said method comprising:

reacting said volume of carbon black material with an oxidizing agent to form a carbon slurry;

removing metallic contaminants from said carbon slurry by solubilizing said metallic contaminants;

filtering said carbon slurry to remove the solubilized metallic contaminants;

increasing a pH level of the carbon slurry to obtain a colloidal system; and

filtering said colloidal system to obtain carbon particles which fall above a predetermined volume threshold;

wherein said carbon particles contain one or more carbon allotropes.

12. The method of claim 11, wherein said colloidal system is a homogeneous and stable colloidal system.

13. The method of claim 11, wherein said colloidal system is a heterogeneous and stable colloidal system.

14. The method of claim 11, wherein said oxidizing agent comprises nitric acid.

15. The method of claim 14, wherein said increasing the pH level of the carbon slurry includes a sonication process.

16. A method for forming a switching device, said method comprising:

depositing a first electrode over a substrate,

depositing a first volume of nanotubes over said first electrode to form a layer of nanotubes,

depositing a second volume of nanoscopic particles, at a predefined ratio relative to said first volume of nanotubes, on said layer of nanotubes to form said composite article, and

depositing a second electrode over said composite article to form the switching device.

17. The method of claim 16, wherein said second volume of nanoscopic particles is deposited using ion implantation.

18. The method of claim 16, wherein said second volume of nanoscopic particles is deposited using vapor deposition.

19. The method of claim 16, wherein said second volume of nanoscopic particles is deposited using sputtering.

20. The method of claim 16, wherein said depositing a first volume of nanotubes is performed by spin coating.