Method to fabricate a thin film non volatile memory device scalable to small sizes

1. A method to fabricate a flexible non-volatile memory device comprising the steps of

providing a flexible substrate;

fabricating a thin film transistor control circuitry on the flexible substrate, the thin film transistor control circuitry having a plurality of contact pads for electrical communication;

fabricating a plurality of bottom electrodes having electrical communication with the control circuitry;

depositing a photoconducting thin film;

fabricating a plurality of top electrodes having electrical communication with the control circuitry, wherein the top electrodes and the bottom electrodes form a cross bar configuration sandwiching the photoconductive thin film; and

providing an electromagnetic radiation source for irradiating a portion of the photoconductive thin film.

2. A method as in claim 1 wherein the fabrication of the bottom electrodes comprises

forming vias with thin film transistor control circuit contact pads;

depositing a metal layer; and

patterning the metal layer into array lines.

3. A method as in claim 1 wherein the deposition of the photoconductive thin film is by inkjet printing or other controlled droplet printing.

4. A method as in claim 1 wherein the deposition of the photoconductive thin film is spin coating.

5. A method as in claim 1 wherein the thin film transistor control circuitry comprises amorphous silicon transistors, microcrystalline silicon transistors or polysilicon transistors.

6. A method as in claim 1 wherein the flexible substrate is a plastic or paper substrate.

7. A method as in claim 1 wherein the electromagnetic radiation source is provided by a plurality of inorganic LED chips.

8. A method to fabricate a flexible RFID device comprising the steps of

providing a flexible substrate;

fabricating a thin film transistor wireless communication circuitry on the flexible substrate, the thin film transistor wireless communication circuitry having a plurality of contact pads for electrical communication;

fabricating a plurality of bottom electrodes having electrical communication with the control circuitry;

depositing a photoconducting thin film;

fabricating a plurality of top electrodes having electrical communication with the control circuitry, wherein the top electrodes and the bottom electrodes form a cross bar configuration sandwiching the photoconductive thin film;

providing an electromagnetic radiation source for irradiating a portion of the photoconductive thin film; and

connecting an antenna in communication with the thin film transistor wireless communication circuitry.

9. A method as in claim 8 further comprising a battery to provide power for the whole circuitry.

10. A method as in claim 8 wherein the fabrication of the bottom electrodes comprises

forming vias with thin film transistor control circuit contact pads;

depositing a metal layer; and

patterning the metal layer into array lines.

11. A method as in claim 8 wherein the deposition of the photoconductive thin film is by inkjet printing or other controlled droplet printing.

12. A method as in claim 8 wherein the deposition of the photoconductive thin film is spin coating.

13. A method as in claim 8 wherein the fabrication of the top electrodes comprises a process temperature of less than 300° C.

14. A method as in claim 8 wherein the fabrication of the top electrodes comprises an indium tin oxide deposition process having process temperature less than 130° C.

15. A method as in claim 8 wherein the fabrication of the top electrodes comprises a process having low ion bombardment to prevent damaging the photoconductive thin film.

16. A method as in claim 8 wherein the low ion bombardment process is a high density plasma process.

17. A method as in claim 8 wherein the thin film transistor control circuitry comprises amorphous silicon transistors, microcrystalline transistors or polysilicon transistors.

18. A method as in claim 8 wherein the flexible substrate is a plastic or paper substrate.

19. A method as in claim 8 wherein the photoconductive film thickness is between 1 to 2 μm.

20. A method as in claim 8 wherein the dark conductivity of the photoconductive film is less than 10 −7 Ohm −1 cm −1 .

21. A method as in claim 8 wherein the photoconductive film is (metal)(beta-decoxyethyl)porphyrins, wherein the metal is selected from a group consisting of Cu, Co, Ni, Pd.

22. A method as in claim 8 wherein the photoconductive film is zinc-octakis(beta-decoxyethyl)porphyrins.

23. A method as in claim 8 wherein the photoconductive film is phthalocyanine, an aromatic compound, or an organo-metallic compound.

24. A method as in claim 8 wherein the electromagnetic radiation source is a visible, infrared or ultraviolet light source.

25. A method as in claim 8 wherein the optoelectronic cross bar memory is positioned on top of thin film transistor control circuitry.

26. A method as in claim 8 wherein the optoelectronic cross bar memory is positioned on the flexible substrate, beside the thin film transistor control circuitry.

27. A method as in claim 8 wherein the top electrode material is transparent to the electromagnetic radiation.

28. A method as in claim 8 wherein the top electrode material is indium tin oxide, another inorganic transparent conducting oxide, a conducting polymer, or poly(ethylenedioxythiophene).

29. A method as in claim 8 wherein the electromagnetic radiation source is positioned on top of the top electrodes.

30. A method as in claim 8 wherein the electromagnetic radiation source is positioned on the edge of the top electrodes.

31. A method as in claim 8 wherein the electromagnetic radiation source is provided by a plurality of inorganic LED chips.