Stack-type image sensor including meta-filter

1. A stack-type image sensor comprising:

a photodiode comprising:

a first photodiode configured to absorb first light of a first wavelength band, and

a second photodiode disposed on the first photodiode and configured to absorb second light of a second wavelength band; and

a meta-filter comprising a plurality of nanostructures that satisfy a subwavelength condition, the meta-filter being configured to reflect light of a previously determined wavelength band, and to transmit light of wavelength bands other than the previously determined wavelength band,

wherein the meta-filter further comprises a first meta-filter disposed in a lower portion of the first photodiode, the first meta-filter being configured to reflect the first light of the first wavelength band to the first photodiode.

2. The stack-type image sensor of claim 1 , wherein the meta-filter further comprises a second meta-filter disposed between the first photodiode and the second photodiode, the second meta-filter being configured to reflect the second light of the second wavelength band to the second photodiode and to transmit the first light of the first wavelength band.

3. The stack-type image sensor claim 1 , wherein the first photodiode is one of (i) a silicon photodiode having no light selectivity and (ii) one of an organic photodiode and a quantum dot photodiode, having light selectivity to sense the first light of the first wavelength band.

4. The stack-type image sensor of claim 3 , wherein the photodiode has a thickness ranging from 30 nm to 250 nm.

5. The stack-type image sensor of claim 1 , wherein the second photodiode is one of an organic photodiode and a quantum dot photodiode, having light selectivity to sense the second light of the second wavelength band.

6. The stack-type image sensor of claim 1 ,

wherein the photodiode further comprises a third photodiode disposed on the second photodiode and configured to absorb third light of a third wavelength band, and

wherein the meta-filter further comprises a third meta-filter disposed between the second photodiode and the third photodiode, and configured to reflect the third light of the third wavelength band to the third photodiode and to transmit light of other wavelength bands.

7. The stack-type image sensor of claim 6 , wherein the third photodiode is one of an organic photodiode and a quantum dot photodiode, having light selectivity to sense the third light of the third wavelength band.

8. The stack-type image sensor of claim 6 , wherein the third wavelength band is one of a red wavelength band, a green wavelength band, and a blue wavelength band,

wherein the second wavelength band is one of the red wavelength band, the green wavelength band, and the blue wavelength band, the second wavelength band being different from the third wavelength band, and

wherein the first wavelength band is one of the red wavelength band, the green wavelength band, and the blue wavelength band, the first wavelength band being different from the second wavelength band and the third wavelength band.

9. The stack-type image sensor of claim 1 , wherein a nanostructure from the plurality of nanostructures has one of a one-dimensional arrangement and a two-dimensional arrangement.

10. The stack-type mage sensor of claim 9 , wherein when the nanostructure has the two-dimensional arrangement, the nanostructure has one of a square shape, a cylindrical shape, a cylindroid shape, a rectangular shape, a triangular pyramid shape, and a conical shape.

11. The stack-type image sensor of claim 9 , wherein when the nanostructure has the one-dimensional arrangement, the nanostructure has a bar shape,

wherein the bar shape has a cross-section of one of a polygonal shape, a circular shape, and an oval shape, and

wherein the polygonal shape is one of a triangular shape, a quadrilateral shape, and a pentagonal shape.

12. The stack-type image sensor of claim 9 , wherein the meta-filter further comprises a surrounding structure that surrounds the nanostructure, the surrounding structure having a lower refractive index than the nanostructure.

13. The stack-type image sensor of claim 12 , wherein the surrounding structure comprises one of a polymer and an oxide.

14. The stack-type image sensor of claim 9 , wherein the meta-filter further comprises a surrounding structure that surrounds the nanostructure, the surrounding structure having a higher refractive index than the nanostructure.

15. The stack-type image sensor of claim 14 , wherein the nanostructure comprises one of a polymer and an oxide, and

wherein the surrounding structure comprises one of single crystal silicon, polycrystalline silicon, amorphous silicon, Si 3 N 4 , GaP, TiO 2 , AlSb, AlAs, AlGaAs, AlGaInP, BP, and ZnGeP 2 .

16. The stack-type image sensor of claim 9 , wherein the meta-filter further comprises a nanostructure arrangement having at least one of a width, an interval, and a symmetrical axis direction varying in a horizontal direction.

17. The stack-type image sensor of claim 1 , wherein a nanostructure from the plurality of nanostructures comprises one of single crystal silicon, polycrystalline silicon, amorphous silicon, silicon nitride (Si 3 N 4 ), gallium phosphide (GaP), gallium arsenide (GaAs), titanium dioxide (TiO 2 ), aluminum antimony (AlSb), aluminum arsenide (AlAs), aluminum gallium arsenide (AlGaAs), aluminum gallium indium phosphide (AlGaInP), boron phosphide (BP), and zinc-germanium diphosphide (ZnGeP 2 ).

18. A stack-type image sensor comprising:

a first photodiode configured to absorb first light of a first wavelength band;

a second photodiode disposed on the first photodiode and configured to absorb second light of a second wavelength band; and

a meta-filter comprising a plurality of nanostructures that satisfy a subwavelength condition, the meta-filter being configured to reflect light of a previously determined wavelength band, and to transmit light of wavelength bands other than the previously determined wavelength band,

wherein the meta-filter further comprises a first meta-filter disposed between the first photodiode and the second photodiode, the first meta-filter being configured to reflect the second light of the second wavelength band to the second photodiode and to transmit the first light of the first wavelength band.

19. The image sensor of claim 18 , wherein the meta-filter further comprises a second meta-filter disposed in a lower portion of the first photodiode, the second meta-filter being configured to reflect the first light of the first wavelength band to the first photodiode.

20. The image sensor of claim 18 , further comprising:

a third photodiode disposed on the second photodiode and configured to absorb third light of a third wavelength band,

wherein the meta-filter further comprises a third meta-filter disposed between the second photodiode and the third photodiode, the third meta-filter being configured to reflect the third light of the third wavelength band to the third photodiode and to transmit the second light of the second wavelength band.