Photodiode and other sensor structures in flat-panel x-ray imagers and method for improving topological uniformity of the photodiode and other sensor structures in flat-panel x-ray imagers based on thin-film electronics

1. A radiation sensor comprising:

a photoconductor detector including in order a first electrode, a photoconductive layer, and an ionizing radiation transmissive second electrode, the photoconductive layer being configured to generate electron-hole pairs upon interaction with ionizing radiation;

pixel circuitry electrically connected to the first electrode and configured to measure an imaging signal indicative of the electron-hole pairs generated in the photoconductive layer; and

a planarization layer disposed on the pixel circuitry between the first electrode and the pixel circuitry such that the first electrode is above a plane including the pixel circuitry;

wherein at least one of the first electrode and the second electrode at least partially overlaps the pixel circuitry, and

wherein the planarization layer at least partially planarizes over a feature of the pixel circuitry.

2. The radiation sensor of claim 1 , wherein:

the pixel circuitry comprises an array of thin-film transistors; and

the planarization layer at least partially planarizes over the array of thin-film transistors.

3. The radiation sensor of claim 1 , wherein:

the pixel circuitry comprises a via interconnect; and

the planarization layer at least partially planarizes over the via interconnect.

4. The radiation sensor of claim 3 , wherein:

the pixel circuitry further comprises a thin-film transistor, the thin-film transistor comprising a source and a drain; and

the via interconnect is connected to the source or to the drain.

5. The radiation sensor of claim 1 , wherein:

the pixel circuitry comprises an in-pixel amplifier element; and

the planarization layer at least partially planarizes over the in-pixel amplifier element.

6. The radiation sensor of claim 1 , wherein:

the pixel circuitry comprises a two-stage in-pixel amplifier element; and

the planarization layer at least partially planarizes over the two-stage in-pixel amplifier element.

7. The radiation sensor of claim 1 , wherein the planarization layer comprises a passivation layer.

8. The radiation sensor of claim 1 , wherein the planarization layer comprises a dielectric layer.

9. The radiation sensor of claim 1 , wherein the planarization layer comprises an insulation layer.

10. The radiation sensor of claim 1 , wherein:

the pixel circuitry comprises address and data lines disposed underneath the photoconductor detector; and

the planarization layer is disposed on the address and data lines.

11. The radiation sensor of claim 1 , wherein the pixel circuitry comprises a via interconnect that extends through the planarization layer.

12. The radiation sensor of claim 2 , wherein the pixel circuitry comprises a silicon semiconductor, an oxide semiconductor, a chalcogenide semiconductor, a cadmium selenide semiconductor, an organic semiconductor, an organic small molecule or polymer semiconductor, carbon nanotubes, or graphene.

13. A radiation sensor comprising:

a scintillation layer configured to emit photons upon interaction with ionizing radiation;

a photodetector including in order a first electrode, a photosensitive layer, and a photon-transmissive second electrode disposed in proximity to the scintillation layer;

said photosensitive layer configured to generate electron-hole pairs upon interaction with a part of said photons;

pixel circuitry electrically connected to the first electrode and configured to measure an imaging signal indicative of the electron-hole pairs generated in the photosensitive layer; and

a planarization layer disposed on the pixel circuitry between the first electrode and the pixel circuitry such that the first electrode is above a plane including the pixel circuitry;

wherein at least one of the first electrode and the second electrode at least partially overlaps the pixel circuitry, and

wherein the planarization layer at least partially planarizes over a feature of the pixel circuitry.

14. The radiation sensor of claim 13 , wherein:

the pixel circuitry comprises an array of thin-film transistors; and

the planarization layer at least partially planarizes over the array of thin-film transistors.

15. The radiation sensor of claim 13 , wherein:

the pixel circuitry comprises a via interconnect; and

the planarization layer at least partially planarizes over the via interconnect.

16. The radiation sensor of claim 15 , wherein:

the pixel circuitry further comprises a thin-film transistor, the thin-film transistor comprising a source and a drain; and

the via interconnect is connected to the source or to the drain.

17. The radiation sensor of claim 13 , wherein:

the pixel circuitry comprises an in-pixel amplifier element; and

the planarization layer at least partially planarizes over the in-pixel amplifier element.

18. The radiation sensor of claim 13 , wherein:

the pixel circuitry comprises a two-stage in-pixel amplifier element; and

the planarization layer at least partially planarizes over the two-stage in-pixel amplifier element.

19. The radiation sensor of claim 13 , wherein the planarization layer comprises a passivation layer.

20. The radiation sensor of claim 13 , wherein the planarization layer comprises a dielectric layer.

21. The radiation sensor of claim 13 , wherein the planarization layer comprises an insulation layer.

22. The radiation sensor of claim 13 , wherein:

the pixel circuitry comprises address and data lines disposed underneath the photoconductor detector; and

the planarization layer is disposed on the address and data lines.

23. The radiation sensor of claim 13 , wherein the pixel circuitry comprises a via interconnect that extends through the planarization layer.

24. The radiation sensor of claim 13 , wherein the pixel circuitry comprises a silicon semiconductor, an oxide semiconductor, a chalcogenide semiconductor, a cadmium selenide semiconductor, an organic semiconductor, an organic small molecule or polymer semiconductor, carbon nanotubes, or graphene.

25. A method for fabricating a radiation sensor, comprising:

forming pixel circuitry elements on a base substrate;

forming a planarization layer over the pixel circuitry elements to at least partially planarize over a feature of the pixel circuitry elements;

forming a hole in the planarization layer to expose a connection to the pixel circuitry elements;

metallizing the patterned hole;

forming a first electrode in electrical contact to the metallized hole; and

forming on the first electrode a layer sensitive to light or ionizing radiation.

26. The method of claim 25 , wherein:

forming the pixel circuitry comprises forming an array of thin-film transistors; and

forming the planarization layer comprises at least partially planarizing over the array of thin-film transistors.

27. The method of claim 25 , wherein:

forming the pixel circuitry comprises forming a via interconnect; and

forming the planarization layer comprises at least partially planarizing over the via interconnect.

28. The method of claim 25 , wherein:

forming the pixel circuitry comprises forming an in-pixel amplifier element; and

forming the planarization layer comprises at least partially planarizing over the in-pixel amplifier element.

29. The method of claim 25 , wherein forming the planarization layer comprises forming a passivation layer.

30. The method of claim 25 , wherein forming the planarization layer comprises forming a dielectric layer.

31. The method of claim 25 , wherein forming the planarization layer comprises forming an insulation layer.

32. The method of claim 25 , wherein:

forming the pixel circuitry comprises forming address and data lines; and

forming the planarization layer comprises forming the planarization layer on the address and data lines.

33. The method of claim 25 , wherein forming the pixel circuitry comprises forming a via interconnect that extends through the planarization layer.

34. The method of claim 25 , wherein forming the pixel circuitry comprises forming, on the base substrate, a silicon semiconductor, an oxide semiconductor, a chalcogenide semiconductor, a cadmium selenide semiconductor, an organic semiconductor, an organic small molecule or polymer semiconductor, carbon nanotubes, or graphene.