Solid-state image device, method for producing the same, and image pickup apparatus
A solid-state image device includes a silicon substrate, and a photoelectric conversion layer arranged on the silicon substrate and lattice-matched to the silicon substrate, the photoelectric conversion layer being composed of a chalcopyrite-based compound semiconductor of a copper-aluminum-gallium-indium-sulfur-selenium-based mixed crystal or a copper-aluminum-gallium-indium-zinc-sulfur-selenium-based mixed crystal.
1. A solid-state image device comprising:
a silicon substrate; and
a photoelectric conversion layer directly on the silicon substrate and lattice-matched to the silicon substrate,
wherein,
the photoelectric conversion layer comprises a first photoelectric conversion layer, a second photoelectric conversion layer, and a third photo electric conversion layer,
the first photoelectric conversion layer comprises CuAl x Ga y In z S 2 , wherein 0≦x≦0.12, 0.38≦y≦0.52, 0.48≦z≦0.50 and x+y+z=1,
the second photoelectric conversion layer comprises CuAl x Ga y In z S 2 , wherein 0.06≦x≦0.41, 0.01≦y≦0.45, 0.49≦z≦0.58 and x+y+z=1, and
the third photoelectric conversion layer comprises CuAl x Ga y S u Se v , wherein 0.31≦x≦0.52, 0.48≦y≦0.69, 1.33≦u≦1.38, 0.62≦v≦0.67, and either x+y+u+v=3 or x+y=1 and u+v=2.
2. The solid-state image device according to claim 1 , wherein the photoelectric conversion layer is a superlattice with layers each having a thickness equal to or smaller than a critical thickness.
3. The solid-state image device according to claim 1 , wherein:
the first photoelectric conversion layer is configured to separate red light and having a band gap of 2.00 eV±0.1 eV;
the second photoelectric conversion layer is configured to separate green light and having a band gap of 2.20 eV±0.15 eV; and
the third photoelectric conversion layer is configured to separate blue light and having a band gap of 2.51 eV±0.2 eV.
4. The solid-state image device according to claim 3 , wherein the first photoelectric conversion layer, the second photoelectric conversion layer, and the third photoelectric conversion layer are stacked in that order from the silicon substrate side.
5. The solid-state image device according to claim 4 , wherein barriers to carriers are formed on the wide-gap side of interfaces between the first photoelectric conversion layer and the second photoelectric conversion layer and between the second photoelectric conversion layer and the third photoelectric conversion layer, or a barrier to carriers is formed on the wide-gap side of the interface between the silicon substrate and the first photoelectric conversion layer.
6. The solid-state image device according to claim 1 wherein the photoelectric conversion layer has a stepwise changing band gap and an energy discontinuity, and an avalanche multiplication is caused by applying a reverse-bias voltage.
7. The solid-state image device according to claim 5 , wherein:
reverse-bias voltages of V R , V G , and V B are sequentially applied, in that order, to the photoelectric conversion layer to sequentially read an R signal, a G signal, and a B signal,
V R represents a reverse-bias voltage for reading an R signal corresponding to red light,
V G represents a reverse-bias voltage for reading a G signal corresponding to green light, and
V B represents a reverse-bias voltage for reading a B signal corresponding to blue light, provided that V B >V G >V R .
8. The solid-state image device according to claim 7 , wherein:
the photoelectric conversion layer has a potential discontinuity,
the first photoelectric conversion layer, the second photoelectric conversion layer, and the third photoelectric conversion layer separate light into red, green, and blue components in the depth direction,
photoelectrons are accumulated by the barriers to carriers,
the reverse-bias voltages of V R , V G , and V B are applied, in that order, in three steps to read the R signal, the G signal, and the B signal, and
avalanche multiplication is caused by the potential discontinuity.
9. The solid-state image device according to any one of claims 1 to 8 , further comprising:
a support substrate;
a wiring portion on the support substrate;
a pixel on the wiring portion, the pixel including a photoelectric conversion portion configured to photoelectrically convert incident light into an electrical signal; and
a silicon layer including a peripheral circuit arranged around the pixel,
wherein,
the photoelectric conversion portion is on the uppermost surface on the incident light side of the silicon layer,
the silicon substrate includes a first electrode layer therein, and
a second electrode layer is on the photoelectric conversion layer.
10. The solid-state image device according to claim 3 or 4 , further comprising:
a PIN structure or a PN structure extending in the horizontal direction of the silicon substrate; and
a barrier formed on the wide-gap side of a portion near the interface between the second photoelectric conversion layer and the third photoelectric conversion layer, between the first photoelectric conversion layer and the second photoelectric conversion layer, or between the first photoelectric conversion layer and the silicon substrate, the barrier having an energy exceeding 26 meV.
11. The solid-state image device according to any one of claims 1 to 3 , further comprising:
a first photoelectric conversion portion including a photoelectric conversion layer;
a second photoelectric conversion portion including a photoelectric conversion layer; and
a third photoelectric conversion portion including a photoelectric conversion layer,
the first to third photoelectric conversion portions being arranged in the planar direction of the silicon substrate,
wherein,
the photoelectric conversion layer in the first photoelectric conversion portion is a first photoelectric conversion layer configured to separate red light,
the photoelectric conversion layer in the second photoelectric conversion portion is a second photoelectric conversion layer configured to separate green light, and
the photoelectric conversion layer in the third photoelectric conversion portion is a third photoelectric conversion layer configured to separate blue light.
12. The solid-state image device according to claim 1 , wherein (a) the first photoelectric conversion layer comprises CuGa 0.52 In 0.48 S 2 , (b) the second photoelectric conversion layer comprises CuAl 0.24 Ga 0.23 In 0.53 S 2 , and (c) the third photoelectric conversion layer comprises CuAl 0.36 Ga 0.64 S 1.28 Se 0.72 .
13. The solid-state image device according to any one of claims 3 to 5 , 7 , 8 , and 11 wherein:
(a) the first photoelectric conversion layer comprises CuGa y In z S u Se v , where 0.52≦y≦0.76, 0.24≦z≦0.48, 1.70≦u≦2.00, 0≦v≦0.30, and either y+z+u+v=3 or y +z =1 and u +v =2;
(b) the second photoelectric conversion layer comprises CuGa y In z Zn w S u Se v , where 0.64≦y≦0.88, 0≦z ≦0.36, 0≦w≦0.12, 0.15≦u≦1.44, 0.56≦v≦1.85, and y+z+w+u+v=2; and
(c) the third photoelectric conversion layer comprises CuGa y Zn w S u Se v , where 0.74≦y≦0.91, 0.09≦w≦0.26, 1.42≦u≦1.49, 0.51≦v ≦0.58, and y+w+u+v=3.
14. A method for producing a solid-state image device, comprising the steps of:
providing a silicon substrate; and
forming a photoelectric conversion layer directly on the silicon substrate while maintaining lattice matching to the silicon substrate,
wherein,
the photoelectric conversion layer comprises a first photoelectric conversion layer, a second photoelectric conversion layer, and a third photo electric conversion layer,
the first photoelectric conversion layer comprises CuAl x Ga y In z S 2 , wherein 0≦x≦0.12, 0.38≦y≦0.52, 0.48≦z≦0.50 and x+y+u+v=1,
the second photoelectric conversion layer comprises CuAl xGa y In z S 2 , wherein 0.06≦x≦0.41, 0.01≦y≦0.45, 0.49≦z≦0.58 and x+y+z =1, and
the third photoelectric conversion layer comprises CuAl x Ga y S u Se v , wherein 0.31 ≦x≦0.52, 0.48≦y≦0.69, 1.33≦u≦1.38, 0.62≦v≦0.67, and either x+y+u+v=3 or x+y=1 and u+v=2.
15. The method according to claim 14 , further comprising the steps of:
forming a first photoelectric conversion portion including the photoelectric conversion layer, a second photoelectric conversion portion including the photoelectric conversion layer, and a third photoelectric conversion portion including the photoelectric conversion layer in such a manner that the first to third photoelectric conversion portions are arranged in the planar direction of the silicon substrate,
wherein,
the photoelectric conversion layer in the first photoelectric conversion portion is a first photoelectric conversion layer configured to separate red light,
the photoelectric conversion layer in the second photoelectric conversion portion is a second photoelectric conversion layer configured to separate green light, and
the photoelectric conversion layer in the third photoelectric conversion portion is a third photoelectric conversion layer configured to separate blue light.
16. An image pickup apparatus comprising:
a light-condensing optical system configured to condense incident light,
a solid-state image device configured to receive light condensed by the light-condensing optical system and perform photoelectric conversion, and
a signal processing unit configured to process a signal obtained by photoelectric conversion,
wherein,
the solid-state image device includes a photoelectric conversion layer on a silicon substrate and lattice-matched to the silicon substrate, the photoelectric conversion layer being composed of a first photoelectric conversion layer, a second photoelectric conversion layer, and a third photo electric conversion layer,
the first photoelectric conversion layer comprises CuAl x Ga y In z S 2 , wherein 0≦x≦0.12, 0.38≦y≦0.52, 0.48≦z≦0.50 and x+y+z=1,
the second shotoelectric conversion la er comprises CuAl x Ga y In z S 2 , wherein 0.06≦x≦0.41, 0.01≦y≦0.45, 0.49≦z≦0.58 and x+y+z=1, and
the third photoelectric conversion layer comprises CuAl x Ga y S u Se v , wherein 0.31 ≦x≦0.52, 0.48≦y≦0.69, 1.33≦u≦1.38, 0.62≦v≦0.67, and either x+y+u+v=3 or x+y=1and u+v= 2 .
17. The solid-state image device according to claim 2 , wherein the photoelectric conversion layer includes (a) the first photoelectric conversion layer configured to separate red light and having a band gap of 2.00 eV±0.1 eV, (b) the second photoelectric conversion layer configured to separate green light and having a band gap of 2.20 eV±0.15 eV, and (c) the third photoelectric conversion layer configured to separate blue light and having a band gap of 2.51 eV±0.2 eV.
18. The solid-state image device according to claim 2 , wherein the photoelectric conversion layer has a stepwise changing band gap and an energy discontinuity, and an avalanche multiplication is caused by applying a reverse-bias voltage.