Electronic devices

• US 20090315017A1
• Filed: 05/09/2006
• Published: 12/24/2009
• Est. Priority Date: 05/09/2005
• Status: Active Grant

• Current Assignee: PragmatIC Printing Ltd.
• Original Assignee: Nano Eprint Limited
• Inventors: Song, Aimin
• Granted Patent: US 8,624,216 B2
• Time in Patent Office: Days
• US Class Current: 257/24
• 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 30/00 Nanotechnology for materials or surface science, e.g. nanocomposites
• CPC Class Codes: B82Y 40/00 Manufacture or treatment of nanostructures
• CPC Class Codes: H01L 29/0688 characterised by the particular shape of a junction between semiconductor regions
• CPC Class Codes: H01L 29/66977 Quantum effect devices, e.g. using quantum reflection, diffraction or interference effects, i.e. Bragg- or Aharonov-Bohm effects
• CPC Class Codes: H01L 29/778 with two-dimensional charge carrier gas channel, e.g. HEMT ; with two-dimensional charge-carrier layer formed at a heterojunction interface H01L29/803 takes precedence
• CPC Class Codes: H10K 10/20 Organic diodes
• CPC Class Codes: H10K 10/23 Schottky diodes
• CPC Class Codes: H10K 10/46 Field-effect transistors, e.g. organic thin-film transistors [OTFT] H10K10/43 takes precedence
• CPC Class Codes: H10K 71/221 by lift-off techniques
• CPC Class Codes: H10K 71/233 by photolithographic etching
• CPC Class Codes: H10K 77/111 Flexible substrates
• CPC Class Codes: H10K 85/113 Heteroaromatic compounds comprising sulfur or selene, e.g. polythiophene

Abstract

An electronic device includes a substrate supporting mobile charge carriers, insulative features formed on the substrate surface to define first and second substrate areas on either side of the insulative features, the first and second substrate areas being connected by an elongate channel defined by the insulative features, the channel providing a charge carrier flow path in the substrate from the first area to the second area, the conductivity between the first and second substrate areas being dependent upon the potential difference between the areas. The mobile charge carriers can be within at least two modes in each of the three dimensions within the substrate. The substrate can be an organic material. The mobile charge carriers can have a mobility within the range 0.01 cm²/Vs to 100 cm²/Vs, and the electronic device may be an RF device. Methods for forming such devices are also described.

Claims

1. An electronic device comprising a substrate supporting mobile charge carriers, insulative features formed on the substrate surface to define first and second substrate areas on either side of the insulative features, the first and second substrate areas being connected by an elongate channel defined by the insulative features, the channel providing a charge carrier flow path in the substrate from the first area to the second area, the conductivity between the first and second substrate areas being dependent upon the potential difference between the areas, wherein the mobile charge carriers can be within at least two modes in each of the three dimensions within the substrate.

2. A device as claimed in claim 1, wherein the substrate layer containing the mobile charge carriers has a thickness greater than the charge carrier wavelength.

8. A device as claimed in claim 1, wherein said mobile charge carriers are electrons.

9. A device as claimed in claim 1, wherein said mobile charge carriers are holes.

10. A device as claimed in claim 1, wherein said substrate is greater than 20 nm thick.

11. A device as claimed in claim 1, wherein the device functions as a diode.

12. A device as claimed in claim 1, wherein the insulative features further define a third substrate area adjacent the elongate channel for application of a voltage to control the conductivity of the channel.

13. A device as claimed in claim 12, wherein the insulative features further define a fourth substrate area adjacent the elongate channel, on the opposite side of the channel to the third substrate area, for application of a voltage to control the conductivity of the channel.

14. A device as claimed in claim 12, wherein the device functions as a transistor.

15. A device as claimed in claim 1, wherein said device is a planar device, with said substrate being positioned within a single layer.

16. A device as claimed in claim 15, wherein said single layer is not sandwiched between two additional layers of other material within a laminate structure.

17. A device as claimed in claim 15, wherein said single layer defines an outer surface of the device.

18. A device as claimed in claim 1, wherein said substrate is formed as a thin film, disposed on an insulative substrate.

19. A device as claimed in claim 1, wherein said substrate comprises at least one of:

semi-conducting polymer;

poly(3-hexyl)thiophene (P3HT);

organic small molecules;

pentacene;

solution processed semiconductor nanoparticle/quantum dot materials; and

said insulative substrate comprises at least one of flexible paper;

polyethylene terephthalate (PET); and

polyethylene naphthalate (PEN) material.

20. A device as claimed in claim 1, further comprising a respective electrical terminal located on each of said areas for application of a voltage thereto.

21. An electronic circuit comprising at least one electronic device as claimed in claim 1.

22. An electronic circuit as claimed in claim 21, comprising a plurality of said electronic devices arranged in parallel between said first and second substrate areas to provide a desired impedance.

23. An electronic circuit as claimed in claim 21, comprising an RFID tag.

3. An electronic device comprising a substrate supporting mobile charge carriers, insulative features formed on the substrate surface to define first and second substrate areas on either side of the insulative features, the first and second substrate areas being connected by an elongate channel defined by the insulative features, the channel providing a charge carrier flow path in the substrate from the first area to the second area, the conductivity between the first and second substrate areas being dependent upon the potential difference between the areas,

wherein the substrate comprises an organic material.

4. An electronic device comprising a substrate supporting mobile charge carriers, insulative features formed on the substrate surface to define first and second substrate areas on either side of the insulative features, the first and second substrate areas being connected by an elongate channel defined by the insulative features, the channel providing a charge carrier flow path in the substrate from the first area to the second area, the conductivity between the first and second substrate areas being dependent upon the potential difference between the areas,

wherein the mobile charge carriers have a mobility within the range 0.01 cm²/Vs to 100 cm²/Vs.

5. A device as claimed in claim 4, where the mobile charge carriers have a mobility of at least 0.1 cm²/Vs.

6. A device according to claim 4, wherein said elongate channel is of predetermined width such that when a voltage difference is applied between said first and second substrate areas such as to cause flow of said mobile charge carriers through said elongate channel, the voltage existing in the second substrate area influences, via said insulative features, the size of depletion regions existing within said elongate channel, whereby the conductivity characteristics of the channel are dependent on said voltage difference.

7. A device according to claim 4, wherein the device comprises a diode for rectifying an RF signal, for example between 0.5 MHz and 1 GHz.

24. A method of manufacture of an electronic device comprising a substrate supporting mobile charge carriers, insulative features formed on the substrate surface to define first and second substrate areas on either side of the insulative features, the first and second substrate areas being connected by an elongate channel defined by the insulative features, the channel providing a charge carrier flow path in the substrate from the first area to the second area, the conductivity between the first and second substrate areas being dependent upon the potential difference between the area;

wherein the method comprises

providing a substrate supporting mobile charge carriers; and

forming insulative features formed on the substrate surface to define first and second substrate areas on either side of the insulative features, the first and second substrate areas being connected by an elongate channel defined by the insulative features, the channel providing a charge carrier flow path in the substrate from the first area to the second area, and the conductivity between the first and second substrate areas being dependent upon the potential difference between the areas.

25. A method of patterning organic films, comprising:

(a) providing a substrate and forming on the substrate a layer of photoresist material;

(b) forming a desired pattern in the photoresist material by a process of photolithography;

(c) forming a layer of organic material on the patterned photoresist material; and

(d) performing a lift off process to selectively remove the organic material so that the organic material conforms to the patterning of the photoresist material.

26. A method as claimed in claim 25, wherein the resulting patterned organic material forms an electronic device comprising a substrate supporting mobile charge carriers, insulative features formed on the substrate surface to define first and second substrate areas on either side of the insulative features, the first and second substrate areas being connected by an elongate channel defined by the insulative features, the channel providing a charge carrier flow path in the substrate from the first area to the second area, and the conductivity between the first and second substrate areas being dependent upon the potential difference between the areas.

27. A method according to claim 25, wherein the organic material comprises polymer material such as P3HT, or small molecule material such as pentacene.

28. A method according to claim 27, wherein a solvent is employed for applying P3HT that is non-reactive with the photoresist material, preferably xylene.

29. A method according to claim 28, wherein the solvent employed to perform the lift off process, preferably diluted acetone, has a sufficiently weak action to avoid lifting off the entire layer of organic material.

30. A method according to claims 25, wherein said substrate is silicon having a layer of silica thereon.

31. A method according to claim 30, wherein the substrate has source and drain contacts, and the patterned organic material forms a conductive channel therebetween.

32. A method according to claim 25, wherein the integrity of the patterned organic material is maintained after lift-off in order that the electrical properties of the material are unaffected.

33. A method of patterning organic films, comprising:

(a) providing a substrate and forming on the substrate a layer of organic material;

(b) allowing the organic material to completely dry;

(c) forming a layer of photoresist material on the organic material;

(d) forming a desired pattern in the photoresist material by a process of photolithography; and

(e) selectively removing the organic material by etching so that the remaining organic material conforms to the patterning of the photoresist material.

34. A method as claimed in claim 33, wherein the resulting patterned organic material forms an electronic device comprising a substrate supporting mobile charge carriers, insulative features formed on the substrate surface to define first and second substrate areas on either side of the insulative features, the first and second substrate areas being connected by an elongate channel defined by the insulative features, the channel providing a charge carrier flow path in the substrate from the first area to the second area, and the conductivity between the first and second substrate areas being dependent upon the potential difference between the areas.

35. A method as claimed in claim 33, wherein the organic material is P3HT.