# US 9,520,514 B2 · Quantum dot infrared photodetector

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- Number: US 9,520,514 B2
- Document ID: US9520514B2
- Status: Granted
- Kind: B2
- Application number: 13/915,497
- Filed: 2013-06-11
- Published: 2014-12-11
- Granted: 2016-12-13
- Earliest claimed: 2013-06-11
- Assignees: National Taiwan University
- Applicants: National Taiwan University
- Inventors: Si-Chen Lee; Jheng-Han Lee; Zong-Ming Wu
- Web page: https://patentgrep.com/patent/US9520514B2

## CPC

- H10F 77/1433: {Quantum dots}
- H10F 39/021: {of image sensors having active layers comprising only Group III-V materials, e.g. GaAs, AlGaAs or InP}
- H10F 39/1847: {Multispectral infrared image sensors having a stacked structure, e.g. NPN, NPNPN or multiple quantum well [MQW] structures}
- H10F 77/14: Shape of semiconductor bodies; Shapes, relative sizes or dispositions of semiconductor regions within semiconductor bodies
- H10F: INORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION

## Abstract

A quantum dot infrared photodetector (QDIP) that can enhance the photocurrent to a greater level than the dark current and/or can be operated at high temperatures is disclosed. The quantum dot infrared photodetector comprises at least one quantum well stack and a plurality of quantum dot layers. The quantum well stack is disposed between the pluralities of quantum dot layers. The quantum well stack comprises two spacer layers and a carrier supplying layer. The carrier supplying layer is disposed between the spacer layers. When the quantum dot infrared photodetector is applied with two bias voltages respectively, the carrier supplying layer supplies carriers to the quantum dot layers.

## Claims

### Claim 1

A quantum dot infrared photodetector, comprising:
two contact layers disposed opposite to each other;
a plurality of quantum dot layers, disposed between the two contact layers; and
at least one quantum well stack, disposed between the quantum dot layers;
wherein the quantum well stack comprises two first spacer layers and a carrier supplying layer disposed between the first spacer layers, the conduction energy band edge alignment of the carrier supplying layer is lower than the conduction energy band edge alignments of the first spacer layers and is higher than the conduction energy band edge alignments of the quantum dot layers;
two second spacer layers disposed inside the contact layers;
the quantum dot layers disposed inside the second spacer layers;
wherein when the contact layers are applied with two bias voltages respectively, the carrier supplying layer supplies carriers to the quantum dot layers;
wherein the first spacer layers and the second spacer layers are the same material and be made of either undoped GaAs or InGaAs.

### Claim 2 (depends on 1)

The quantum dot infrared photodetector according to claim 1, wherein the carrier supplying layer is doped with n-type dopants.

### Claim 3 (depends on 2)

The quantum dot infrared photodetector according to claim 2, wherein the n-type dopants comprise Si.

### Claim 4 (depends on 3)

The quantum dot infrared photodetector according to claim 3, wherein the concentration of the Si dopants is between about 9×1017 cm−3 and about 1×1016 cm−3.

### Claim 5 (depends on 1)

The quantum dot infrared photodetector according to claim 1, wherein the carrier supplying layer comprises InGaAs, GaAs, InGaAsP, or AlInGaAs.

### Claim 6 (depends on 1)

The quantum dot infrared photodetector according to claim 1, wherein the quantum dot layers comprise InAs or InGaAs.

### Claim 7 (depends on 1)

The quantum dot infrared photodetector according to claim 1, wherein the contact layers are doped with n-type dopants.

### Claim 8 (depends on 7)

The quantum dot infrared photodetector according to claim 7, wherein the contact layers comprise GaAs, InGaAsP, or InAlGaAs.

### Claim 9 (depends on 1)

The quantum dot infrared photodetector according to claim 1, further comprising at least one blocking layer disposed between the second spacer layers and the contact layers.

### Claim 10 (depends on 1)

The quantum dot infrared photodetector according to claim 1, wherein the number of stacks of the quantum dot layer/first spacer layer is three, five, or ten stacks.

### Claim 11

A quantum dot infrared photodetector, comprising:
a first contact layer and a second contact layer disposed opposite to each other;
a quantum dot layer, disposed between the first and second contact layers; and
a n-doped layer cladded by two undoped spacer layers, and a quantum well stack is composed of the n-doped layer and the two undoped spacer layers, the conduction energy band edge alignment of the n-doped layer is lower than the conduction energy band edge alignments of the neighboring undoped spacer layers, the conduction energy band edge alignment of the n-doped layer is higher than the conduction energy band edge alignment of the quantum dot layer;
two spacer layers disposed inside the first and second contact layers;
the quantum dot layer disposed inside the spacer layers;
wherein the n-doped layer is disposed between the first contact layer and the quantum dot layer or between the second contact layer and the quantum dot layer;
wherein when the first and second contact layers are applied with two bias voltages, the n-doped layer supplies carriers to the quantum dot layer;
wherein the two undoped spacer layers comprise undoped GaAs or InGaAs, and the two spacer layers comprise GaAs or InGaAs.

### Claim 12 (depends on 11)

The quantum dot infrared photodetector according to claim 11, wherein the n-doped layer comprises Si dopants.

### Claim 13 (depends on 12)

The quantum dot infrared photodetector according to claim 12, wherein the concentration of the Si dopants is between 9×1017 cm−3 and 1×1017 cm−3.

### Claim 14 (depends on 11)

The quantum dot infrared photodetector according to claim 11, wherein the n-doped layer comprises InGaAs, GaAs, InGaAsP, or AlInGaAs.

### Claim 15 (depends on 11)

The quantum dot infrared photodetector according to claim 11, wherein the quantum dot layer comprises InAs.

### Claim 16 (depends on 11)

The quantum dot infrared photodetector according to claim 11, wherein the first and second contact layers are doped with n-type dopants.

### Claim 17 (depends on 16)

The quantum dot infrared photodetector according to claim 16, wherein the first and second contact layers comprise GaAs, InGaAsP, or InAlGaAs.

### Claim 18 (depends on 11)

The quantum dot infrared photodetector according to claim 11, further comprising at least one blocking layer disposed between the spacer layer and the first contact layer or between the spacer layer and the second contact layer.

### Claim 19 (depends on 11)

The quantum dot infrared photodetector according to claim 11, wherein the number of stacks of the quantum dot layer/ spacer layer is three, five, or ten stacks.