CARBON NANOTUBE PRINTED ELECTRONICS DEVICES

• US 20150108429A1
• Filed: 10/22/2013
• Published: 04/23/2015
• Est. Priority Date: 10/22/2013
• Status: Abandoned Application

• Current Assignee: Harsha Sudarsan Uppili
• Original Assignee: Harsha Sudarsan Uppili
• Inventors: Uppili, Harsha Sudarsan
• Application Number:
  US14/060,430
• Publication Number:
  US 20150108429A1
• Time in Patent Office: Days
• US Class Current: 257/20
• CPC Class Codes: B82Y 10/00 Nanotechnology for information processing, storage or transmission, e.g. quantum computing or single electron logic
• CPC Class Codes: B82Y 40/00 Manufacture or treatment of nanostructures
• CPC Class Codes: H01L 29/0673 oriented parallel to a substrate
• CPC Class Codes: H01L 29/78696 characterised by the structure of the channel, e.g. multichannel, transverse or longitudinal shape, length or width, doping structure, or the overlap or alignment between the channel and the gate, the source or the drain, or the contacting structure of the channel H01L29/78612 takes precedence; transistors having a drain offset region or a lightly doped drain [LDD] H01L29/78621
• CPC Class Codes: H10K 10/484 characterised by the channel regions
• CPC Class Codes: H10K 71/40 Thermal treatment, e.g. annealing in the presence of a solvent vapour
• CPC Class Codes: H10K 85/221 Carbon nanotubes

Abstract

Electronic devices include a network of purified and randomly aligned carbon nanotubes. The electronic devices include conductive regions that comprise conductive inks, and substrates such as flexible plastic materials including PET. Networks of randomly aligned carbon nanotubes are exposed to UV radiation to convert metallic carbon nanotubes to semiconductive carbon nanotubes. Conductive regions are printed onto a substrate using printing techniques such as inkjet printing and gravure printing. Devices are fabricated at low temperatures, without annealing and without vacuum.

Claims

1. An electronic device, comprising:

a first conductive region and a second conductive region; and

a network of purified and randomly oriented carbon nanotubes electrically coupled to the first and the second conductive regions, wherein the network of purified and randomly oriented carbon nanotubes comprises both metallic and semiconductive carbon nanotubes such that greater than about 99 percent of the carbon nanotubes in the network are semiconductive nanotubes.

2. The electronic device of claim 1, further comprising:

a substrate having a top surface and a bottom surface, wherein the first conductive region and the second conductive region are situated on the top surface and separated by a third region and at least a portion of the network of purified and randomly oriented carbon nanotubes is situated within the third region.

3. The electronic device of claim 2, wherein the substrate comprises a material selected from the following:

a plastic, polyethylene terephthalate (PET), a flexible material, a material having a surface roughness that is between about 1 and 20 times an average diameter of the carbon nanotubes, and an adhesion promoting material.

4. The electronic device of claim 1, wherein the network of purified and randomly oriented carbon nanotubes is achieved by treating the network with UV radiation to convert metallic nanotubes into semiconductive nanotubes.

5. The electronic device of claim 1, wherein the network of purified and randomly oriented carbon nanotubes includes between about 99.5 percent and about 99.9 percent semiconductive nanotubes.

6. The electronic device of claim 2, wherein the first conductive region is a source region, the second conductive region is a drain region, the third conductive region is a channel region, the device is a transistor, and the transistor further comprises:

a dielectric layer situated so that the source region, the drain region, and the network of nanotubes are situated between the substrate and the dielectric layer; and

a gate electrode situated above the dielectric layer and the channel region and electrically insulated from the source region and the drain region by the dielectric layer.

7. The electronic device of claim 6, wherein the dielectric layer comprises polyimide.

8. The electronic device of claim 1, wherein the first and the second conductive regions comprise unannealed silver nanoparticle ink.

9. A logic circuit comprising a plurality of electronic devices according to claim 1.

10. A method of fabricating an electronic device, comprising:

depositing carbon nanotube ink including both metallic and semiconductive carbon nanotubes on a substrate to form a randomly aligned network of carbon nanotubes; and

applying UV radiation to the randomly aligned network of carbon nanotubes to convert some of the metallic carbon nanotubes into semiconductive carbon nanotubes.

11. The method of claim 10, wherein about 99 percent or less of the network of randomly aligned carbon nanotubes are semiconductive nanotubes before the applying of the UV radiation, and more than about 99 percent of the plurality of randomly aligned carbon nanotubes are semiconductive nanotubes after the applying of the UV radiation.

12. The method of claim 10, further comprising:

printing a first region using conductive ink;

printing a second region using conductive ink, wherein the randomly aligned network of carbon nanotubes electrically couples the first region to the second region.

13. The method of claim 12, wherein the printing of the first and the second regions is performed using an inkjet printer or gravure printing techniques.

14. The method of claim 12, wherein the printing, the depositing and the applying are performed in an atmospheric pressure between about 80 kPa and about 105 kPa and at a temperature less than about 100 degrees Celsius.

15. The method of claim 12, further comprising:

depositing a dielectric layer above the first region, the second region, and the network of randomly aligned carbon nanotubes; and

depositing a conductive material above the dielectric layer to form a gate electrode electrically insulated from the first and the second regions by the dielectric layer.

16. The method of claim 12, wherein a resistance of the randomly aligned network of carbon nanotubes between the first and the second regions after the application of the UV radiation is at least two times greater than a resistance of the randomly aligned network of carbon nanotubes between the first and the second regions before the application of the UV radiation.

17. A device, comprising:

an adhesion promoting substrate layer; and

a network of purified and randomly-oriented carbon nanotubes situated on the adhesion promoting substrate layer, wherein the network of purified and randomly oriented carbon nanotubes comprises between about 0.1% and about 0.9% photo-oxidized carbon nanotubes.

18. The device of claim 17, further comprising:

a plurality of pairs of printed source and drain regions comprising conductive ink, each pair of source and drain regions connected to each other by a network of nanotubes formed from the plurality of randomly-oriented carbon nanotubes.

19. The device of claim 17, wherein the substrate is selected from the following:

a flexible material, polyethylene terephthalate (PET), or a plastic.

20. The device of claim 17, wherein the device contains no layer of adhesion promoter modified material.