Full color single pixel including doublet or quadruplet si nanowires for image sensors

1. An image sensor comprising a substrate and one or more of pixels thereon, wherein each of the pixels comprises a first subpixel and a second subpixel; the first subpixel comprises a first nanowire operable to generate an electrical signal upon exposure to light of a first wavelength; the second subpixel comprises a second nanowire operable to generate an electrical signal upon exposure to light of a second wavelength different from the first wavelength; the first and second nanowires extend essentially perpendicularly from the substrate, wherein the first nanowire and/or the second nanowire has a transistor therein or thereon.

2. The image sensor of claim 1 , wherein each pixel of the image sensor further comprises one or more photodiodes located between the substrate and the first and second nanowires.

3. The image sensor of claim 1 , wherein the substrate comprises silicon, silicon oxide, silicon nitride, sapphire, diamond, silicon carbide, gallium nitride, germanium, indium gallium arsenide, lead sulfide and/or a combination thereof.

4. The image sensor of claim 1 , wherein at least one pixel comprises a clad; the first subpixel and the second subpixel of the at least one pixel are embedded in the clad.

5. The image sensor of claim 4 , further comprising a material in space between the pixels.

6. The image sensor of claim 4 , wherein the clad comprises silicon nitride, silicon oxide, and/or a combination thereof.

7. The image sensor of claim 4 , wherein the clad is substantially transparent to visible light.

8. The image sensor of claim 4 , wherein the first and second nanowires have refractive indexes equal to or greater than a refractive index of the clad.

9. The image sensor of claim 5 , wherein the material has a refractive index smaller than a refractive index of the clad.

10. The image sensor of claim 1 , wherein the first nanowire and the second nanowire have different absorption spectra.

11. The image sensor of claim 1 , wherein the first nanowire and the second nanowire have a distance of at least 100 nm.

12. The image sensor of claim 1 , wherein each of the first and second nanowires has a p-n or p-i-n junction therein.

13. The image sensor of the claim 1 , wherein the electrical signal comprise an electrical voltage, an electrical current, an electrical conductance or resistance, and/or a change thereof.

14. The image sensor of claim 1 , wherein the first nanowire and/or the second nanowire has a surface passivation layer.

15. The image sensor of claim 1 , being operable to absorb at least 50% of all visible light impinged thereon.

16. The image sensor of claim 1 , further comprising electronic circuitry operable to detect electrical signals generated by the first and second nanowires.

17. The image sensor of claim 1 , wherein the first and second nanowires comprise silicon.

18. The image sensor of claim 1 , wherein the first nanowire has a radius of about 25 nm and the second nanowire has a radius of about 40 nm.

19. The image sensor of claim 4 , wherein the clad has a cylindrical shape with a diameter of about 300 nm.

20. The image sensor of claim 1 , wherein the pixels have different orientations.

21. The image sensor of claim 2 , wherein the photodiodes have absorption spectra different from absorption spectra of the first and second nanowires.

22. The image sensor of claim 1 , wherein each of the pixels further comprises a third subpixel and the third subpixel comprises a third nanowire operable to generate an electrical signal upon exposure to light of a third wavelength different from the first and second wavelengths, wherein the third nanowire extends essentially perpendicularly from the substrate.

23. The image sensor of claim 22 , wherein the third nanowire comprises silicon.

24. The image sensor of claim 22 , wherein the third nanowire has a radius of about 45 nm.

25. The image sensor of claim 22 , wherein each of the pixels further comprises a fourth subpixel and the fourth subpixel comprises a fourth nanowire operable to generate an electrical signal upon exposure to light of a fourth wavelength different from the first, second and third wavelengths, wherein the fourth nanowire extends essentially perpendicularly from the substrate.

26. The image sensor of claim 25 , wherein the fourth nanowire comprises silicon.

27. The image sensor of claim 25 , wherein the fourth nanowire has a radius of about 40 nm.

28. The image sensor of claim 4 , further comprising couplers above each of the pixels, each of the couplers having a convex surface and being effective to focus substantially all visible light impinged thereon into the clad.

29. The image sensor of claim 28 , wherein each of the couplers has substantially the same footprint as the pixel underneath.

30. The image sensor of claim 1 , further comprising an infrared filter operable to prevent infrared light from reaching the pixels.

31. The image sensor of claim 1 , wherein the image sensor does not comprise an infrared filter.

32. The image sensor of claim 2 , further comprising electronic circuitry operable to detect electrical signals from the photodiodes.

33. A method of manufacturing an image sensor, comprising dry etching or VLS growth, wherein the image sensor comprises a substrate and one or more of pixels thereon, wherein each of the pixels comprises at a first subpixel and a second subpixel, the first subpixel comprises a first nanowire operable to generate an electrical signal upon exposure to light of a first wavelength, the second subpixel comprises a second nanowire operable to generate an electrical signal upon exposure to light of a second wavelength different from the first wavelength, wherein the first and second nanowires extend essentially perpendicularly from the substrate, wherein the first nanowire and/or the second nanowire has a transistor therein or thereon.

34. A method of sensing an image comprises:

projecting the image onto an image sensor, wherein the image sensor comprises a substrate and one or more of pixels thereon, wherein each of the pixels comprises at a first subpixel and a second subpixel, the first subpixel comprises a first nanowire operable to generate an electrical signal upon exposure to light of a first wavelength, the second subpixel comprises a second nanowire operable to generate an electrical signal upon exposure to light of a second wavelength different from the first wavelength, wherein the first and second nanowires extend essentially perpendicularly from the substrate, wherein the first nanowire and/or the second nanowire has a transistor therein or hereon;

detecting the electrical signals from the first nanowire and the second nanowire; and

calculating a color of each pixel from the electrical signals.

35. The image sensor of claim 1 , wherein the first nanowire and the second nanowire are embedded in a same clad.

36. The image sensor of claim 1 , wherein at least one pixel comprises a clad; wherein the clad covers substantially an entire sidewall of the first nanowire.

37. The image sensor of claim 22 , color-matching functions of the first, second and third subpixels are substantially the same as the color matching functions of the CIE 1931 2° Standard Observer or the CIE 196410° Standard Observer.

38. The image sensor of claim 1 , wherein different pixels of the one or more of pixels comprise spatially separated clads.