Infrared detector, imaging device, and imaging system
An infrared detector includes a quantum dot structure, and an electrode that is coupled to the quantum dot structure, wherein the quantum dot structure is obtained by stacking a plurality of structures each including a quantum dot, a first barrier layer under the quantum dot and a second barrier layer over the quantum dot to cover the quantum dots, and an intermediate layer under the first barrier layer, and wherein the first barrier layer includes a first region and a second region having a lower Al concentration than that of the intermediate layer between the first region and the intermediate layer.
1. An infrared detector comprising:
a quantum dot structure; and
an electrode that is coupled to the quantum dot structure,
wherein the quantum dot structure is obtained by stacking a plurality of structures each including
a quantum dot,
a first barrier layer under the quantum dot and a second barrier layer over the quantum dot to cover the quantum dots, and
an intermediate layer under the first barrier layer, and
wherein the first barrier layer includes a first region and a second region having a lower Al concentration than that of the intermediate layer between the first region and the intermediate layer.
2. The infrared detector according to claim 1 ,
wherein the first region has a larger energy gap than that of the intermediate layer, and the second region has a smaller energy gap than that of the intermediate layer.
3. The infrared detector according to claim 1 ,
wherein the second region has Al a Ga 1-a As (0≤a<1).
4. The infrared detector according to claim 1 ,
wherein the second region has In a Ga 1-a P (0≤a≤1).
5. The infrared detector according to claim 3 ,
wherein the intermediate layer has Al b Ga 1-b As (0<b≤1), and the first region has Al c Ga 1-c As (0<c≤1), where b<c.
6. The infrared detector according to claim 5 ,
wherein the second barrier layer has Al d Ga 1-d As (0<d≤1), where b<d.
7. The infrared detector according to claim 1 ,
wherein the second region has a mixed crystal of one kind or two or more kinds selected from the group consisting of GaAs, InAs, GaSb, InSb, GaP, and InP.
8. The infrared detector according to claim 1 ,
wherein the second barrier layer includes a third region and a fourth region having a lower Al concentration than that of the intermediate layer over an upper portion of the third region.
9. The infrared detector according to claim 1 ,
wherein the first region has a thickness of 2 nm or less.
10. An imaging device comprising:
a plurality of infrared detectors; and
a readout circuit that drives the infrared detectors,
wherein the infrared detector includes
a quantum dot structure, and
an electrode that is coupled to the quantum dot structure,
wherein the quantum dot structure is obtained by stacking a plurality of structures each including
a quantum dot,
a first barrier layer under the quantum dot and a second barrier layer over the quantum dot to cover the quantum dots, and
an intermediate layer under the first barrier layer, and
wherein the first barrier layer includes a first region and a second region having a lower Al concentration than that of the intermediate layer between the first region and the intermediate layer.
11. The imaging device according to claim 10 ,
wherein the second region has Al a Ga 1-a As (0≤a<1).
12. The imaging device according to claim 10 ,
wherein the second region has In a Ga 1-a P (0≤a≤1).
13. An imaging system comprising:
an infrared sensor assembly;
a controller that controls the infrared sensor unit; and
a display that displays a captured infrared image,
wherein the infrared sensor assembly includes
an infrared imaging device,
a cooler that cools the infrared imaging device, and
a lens for incident infrared rays to the infrared imaging device,
wherein the infrared imaging device includes
a plurality of infrared detectors, and
a readout that drives the infrared detectors,
wherein the infrared detector includes
a quantum dot structure, and
an electrode that is coupled to the quantum dot structure,
wherein the quantum dot structure is obtained by stacking a plurality of structures each including
a quantum dot,
a first barrier layer under the quantum dot and a second barrier layer over the quantum dot to cover the quantum dots, and
an intermediate layer under the first barrier layer, and
wherein the first barrier layer includes a first region and a second region having a lower Al concentration than that of the intermediate layer between the first region and the intermediate layer.
14. The imaging system according to claim 13 ,
wherein the second region has Al a Ga 1-a As (0≤a<1).
15. The imaging system according to claim 13 ,
wherein the second region has In a Ga 1-a P (0≤a≤1).