Image sensors and electronic devices
An image sensor may include a first photo-sensing device on a semiconductor substrate and configured to sense light of a first wavelength spectrum, and second and third photo-sensing devices integrated in the semiconductor substrate and configured to sense light of a second and third wavelength spectrum, respectively. The first photo-sensing device may overlap each of the second and third photo-sensing devices in a thickness direction of the semiconductor substrate. The second and third photo-sensing devices do not overlap in the thickness direction and each have an upper surface, a lower surface, and a doped region therebetween. The third photo-sensing device includes an upper surface deeper further from the upper surface of the semiconductor substrate than the upper surface of the second photo-sensing device and a doped region thicker than the doped region of the second photo-sensing device. The image sensor may omit the first photo-sensing device.
1. An image sensor, comprising:
a first photo-sensing device on a semiconductor substrate, the first photo-sensing device being configured to sense light in a first wavelength spectrum associated with a first color,
a second photo-sensing device integrated in the semiconductor substrate, the second photo-sensing device being configured to sense light of in a second wavelength spectrum associated with a second color, and
a third photo-sensing device integrated in the semiconductor substrate, the third photo-sensing device being configured to sense light in a third wavelength spectrum associated with a third color,
wherein the first photo-sensing device and the second photo-sensing device are overlapped with each other in a thickness direction of the semiconductor substrate, the thickness direction being perpendicular to an upper surface of the semiconductor substrate,
wherein the first photo-sensing device and the third photo-sensing device are overlapped with each other in the thickness direction,
wherein the second photo-sensing device and the third photo-sensing device are not overlapped with each other in the thickness direction,
wherein the second photo-sensing device and the third photo-sensing device each include
an upper surface that is proximate to the upper surface of the semiconductor substrate,
a lower surface facing the upper surface and distal from the upper surface of the semiconductor substrate, and
a doped region between the upper surface and the lower surface,
wherein the upper surface of the third photo-sensing device is distal from the upper surface of the semiconductor substrate in relation to the upper surface of the second photo-sensing device, and
wherein the doped region of the third photo-sensing device is thicker, in the thickness direction, than the doped region of the second photo-sensing device,
wherein an external quantum efficiency at a wavelength included in the third wavelength spectrum of the third photo-sensing device is different based on a thickness, in the thickness direction, of the doped region of the third photo-sensing device, and
wherein the thickness of the doped region of the third photo-sensing device satisfies Relationship Equation 1:
2.5×EQE( T 3 )≥EQE( T 2 ) [Relationship Equation 1]
wherein, in Relationship Equation 1,
EQE (T 3 ) is external quantum efficiency at a wavelength included in the third wavelength spectrum based on the thickness of the doped region of the third photo-sensing device in the thickness direction being a thickness T 3 ,
EQE (T 2 ) is external quantum efficiency at a wavelength included in the second wavelength spectrum based on the thickness of the doped region of the second photo-sensing device in the thickness direction being a thickness T 2 , and
T 3 >T 2 .
2. The image sensor of claim 1 , wherein the image sensor does not include any color filter.
3. The image sensor of claim 1 , further comprising:
an insulation layer between the semiconductor substrate and the first photo-sensing device.
4. The image sensor of claim 1 , wherein the upper surface of the third photo-sensing device is distal from the upper surface of the semiconductor substrate in relation to the upper surface of the second photo-sensing device by a distance that is equal to or greater than about 300 nm.
5. The image sensor of claim 4 , wherein the upper surface of the second photo-sensing device is at a depth of about 0 nm to about 200 nm from the upper surface of the semiconductor substrate in the thickness direction.
6. The image sensor of claim 1 , wherein
a wavelength selectivity of the third wavelength spectrum relative to the second wavelength spectrum of the third photo-sensing device varies depending on a depth of the upper surface of the third photo-sensing device from the upper surface of the semiconductor substrate in the thickness direction, and
the depth of the upper surface of the third photo-sensing device from the upper surface of the semiconductor substrate in the thickness direction is a depth D 3 that satisfies Relationship Equation 2:
EQE(λ 3 )≥3×EQE(λ 2 ) [Relationship Equation 2]
wherein, in Relationship Equation 2,
EQE (λ 3 ) is external quantum efficiency at a wavelength (λ 3 ) included in the third wavelength spectrum of the third photo-sensing device based on the depth of the upper surface of the third photo-sensing device in the semiconductor substrate being the depth D 3 , and
EQE (λ 2 ) is external quantum efficiency at a wavelength (λ 2 ) included in the second wavelength spectrum of the third photo-sensing device based on the depth of the upper surface of the third photo-sensing device in the semiconductor substrate being the depth D 3 .
7. The image sensor of claim 6 , wherein the depth of the upper surface of the third photo-sensing device from the upper surface of the semiconductor substrate in the thickness direction is about 400 nm to about 1 μm.
8. The image sensor of claim 1 , wherein the doped region of the third photo-sensing device is about 1.5 times to about 5 times thicker, in the thickness direction, than the doped region of the second photo-sensing device.
9. The image sensor of claim 1 , wherein the thickness T 3 is greater than or equal to about 1 μm.
10. The image sensor of claim 1 , wherein the thickness T 2 is about 200 nm to about 800 nm.
11. The image sensor of claim 1 , wherein
the thickness T 3 is about 1 μm to about 3 μm, and
the thickness T 2 is about 300 nm to about 700 nm.
12. The image sensor of claim 1 , wherein an external quantum efficiency at a wavelength included in the second wavelength spectrum of the second photo-sensing device is about 1.1 times to about 2.5 times higher than an external quantum efficiency at a wavelength included in the third wavelength spectrum of the third photo-sensing device.
13. The image sensor of claim 1 , wherein differences among external quantum efficiency of the image sensor at a wavelength included in the first wavelength spectrum, external quantum efficiency of the image sensor at a wavelength included in the second wavelength spectrum, and external quantum efficiency of the image sensor at a wavelength included in the third wavelength spectrum is less than or equal to about 50%.
14. The image sensor of claim 1 , wherein the third wavelength spectrum includes longer wavelengths than the second wavelength spectrum.
15. The image sensor of claim 1 , wherein the first color is green, the second color is blue, and the third color is red.
16. The image sensor of claim 1 , wherein
the first photo-sensing device includes
a first electrode and a second electrode facing each other, and
a photoelectric conversion layer between the first electrode and the second electrode.
17. The image sensor of claim 16 , further comprising:
an insulation layer between the semiconductor substrate and the first photo-sensing device, and
the first electrode is integrated in the insulation layer.
18. The image sensor of claim 16 , wherein
the first photo-sensing device further includes a buffer layer between the first electrode and the photoelectric conversion layer or between the second electrode and the photoelectric conversion layer,
wherein the buffer layer includes a lanthanide element, calcium (Ca), potassium (K), aluminum (Al), or an alloy thereof.
19. An electronic device comprising the image sensor of claim 1 .
20. An image sensor, comprising:
a first photo-sensing device integrated in a semiconductor substrate, the first photo-sensing device being configured to sense light of a first wavelength spectrum, and
a second photo-sensing device integrated in the semiconductor substrate, the second photo-sensing device being configured to sense light of a second wavelength spectrum,
wherein the first photo-sensing device and the second photo-sensing device are not overlapped with each other in a thickness direction extending perpendicular to an upper surface of the semiconductor substrate and are spaced apart from each other in a surface direction extending parallel to the upper surface of the semiconductor substrate,
wherein the first photo-sensing device and the second photo-sensing device each include
an upper surface that is proximate to the upper surface of the semiconductor substrate,
a lower surface facing the upper surface and distal from the upper surface of the semiconductor substrate, and
a doped region between the upper surface and the lower surface, wherein the second photo-sensing device has at least one of
the upper surface of the second photo-sensing device being distal from the upper surface of the semiconductor substrate in relation to the upper surface of the first photo-sensing device, or
the doped region of the second photo-sensing device being thicker, in the thickness direction, than the doped region of the first photo-sensing device,
wherein an external quantum efficiency at a wavelength included in the second wavelength spectrum of the second photo-sensing device is different based on a thickness, in the thickness direction, of the doped region of the second photo-sensing device, and
wherein the thickness of the doped region of the second photo-sensing device satisfies Relationship Equation 1:
2.5×EQE( T 2 )≥EQE( T 1 ) [Relationship Equation 1]
wherein, in Relationship Equation 1,
EQE (T 2 ) is external quantum efficiency at a wavelength included in the second wavelength spectrum based on the thickness of the doped region of the second photo-sensing device in the thickness direction being a thickness T 2 ,
EQE (T 1 ) is external quantum efficiency at a wavelength included in the first wavelength spectrum based on the thickness of the doped region of the first photo-sensing device in the thickness direction being a thickness T 1 , and
T 2 >T 1 .
21. The image sensor of claim 20 , further comprising:
a third photo-sensing device on the semiconductor substrate, the third photo-sensing device being configured to sense light of a third wavelength spectrum,
wherein the third photo-sensing device is overlapped with at least one of the first photo-sensing device or the second photo-sensing device in the thickness direction.
22. The image sensor of claim 21 , wherein
the third photo-sensing device is overlapped with the first photo-sensing device in the thickness direction, and
the third photo-sensing device is overlapped with the second photo-sensing device in the thickness direction.
23. The image sensor of claim 21 , further comprising:
a fourth photo-sensing device on the semiconductor substrate, the fourth photo-sensing device being configured to sense light of a fourth wavelength spectrum,
wherein the fourth photo-sensing device overlaps with the third photo-sensing device in the surface direction,
wherein the third photo-sensing device is overlapped with the first photo-sensing device and is not overlapped with the second photo-sensing device in the thickness direction, and
wherein the fourth photo-sensing device is overlapped with the second photo-sensing device and is not overlapped with the first photo-sensing device in the thickness direction.
24. The image sensor of claim 20 , wherein the first photo-sensing device and the second photo-sensing device are at least partially overlapped with each other in the surface direction, such that the lower surface of the first photo-sensing device is equidistant or distal from the upper surface of the semiconductor substrate in relation to the upper surface of the second photo-sensing device.
25. The image sensor of claim 20 , wherein the first photo-sensing device and the second photo-sensing device are not overlapped with each other in the surface direction, such that the lower surface of the first photo-sensing device is proximate to the upper surface of the semiconductor substrate in relation to the upper surface of the second photo-sensing device.
26. The image sensor of claim 20 , wherein the image sensor does not include any color filter.
27. An electronic device including the image sensor of claim 20 .