RADIATION DETECTOR ELEMENT AND IMAGER COMPRISING AN ASSEMBLY OF RADIATION DETECTOR ELEMENTS

• US 20180366511A1
• Filed: 12/16/2016
• Published: 12/20/2018
• Est. Priority Date: 12/16/2015
• Status: Active Grant

• Current Assignee: Commissariat a L'Energie Atomique (AES Corporation), Thales SA
• Original Assignee: Commissariat a L'Energie Atomique (AES Corporation), Thales SA
• Inventors: LEGOFF, Florian, REVERCHON, Jean-Luc, KAZMIERSKI, Christophe, DECOBERT, Jean
• Granted Patent: US 10,892,294 B2
• Time in Patent Office: Days
• CPC Class Codes: H01L 27/14601 Structural or functional details thereof
• CPC Class Codes: H01L 27/14603 Special geometry or disposition of pixel-elements, address-lines or gate-electrodes
• CPC Class Codes: H01L 27/14634 Assemblies, i.e. Hybrid structures
• CPC Class Codes: H01L 27/14636 Interconnect structures
• CPC Class Codes: H01L 27/14638 Structures specially adapted for transferring the charges across the imager perpendicular to the imaging plane
• CPC Class Codes: H01L 27/14641 Electronic components shared by two or more pixel-elements, e.g. one amplifier shared by two pixel elements
• CPC Class Codes: H01L 27/14647 Multicolour imagers having a stacked pixel-element structure, e.g. npn, npnpn or MQW elements
• CPC Class Codes: H01L 27/14649 Infrared imagers
• CPC Class Codes: H01L 27/14652 Multispectral infrared imagers, having a stacked pixel-element structure, e.g. npn, npnpn or MQW structures
• CPC Class Codes: H01L 27/1469 Assemblies, i.e. hybrid integration
• CPC Class Codes: H01L 27/14694 The active layers comprising only AIIIBV compounds, e.g. GaAs, InP
• CPC Class Codes: H01L 31/101 Devices sensitive to infrared, visible or ultraviolet radiation

Abstract

The invention relates to a radiation detector element (10) comprising a stack (15) of layers superimposed in a stacking direction (Z), the stack (15) having a first face (25) and a second face (30) and comprising a radiation-absorbing layer (35) consisting of a first semiconductor material (M1) having a first band gap value and at least one barrier layer (40) consisting of a second semiconductor material (M2) having a second band gap value, the second band gap value being strictly higher than the first band gap value. The second face (30) has at least one strip (105) defined in the stacking direction (Z) by the barrier layer (40), the strip (105) consisting of the second semiconductor material (M2) and having a doping of the first type and a free carrier density higher than or equal to 1.1017 cm−3.

Claims

1. A radiation detector element comprising:

a stack of layers superimposed in a stacking direction, the stack having a first face and a second face and comprising a radiation-absorbing layer consisting of a first semiconductor material having a first band gap value and at least one barrier layer consisting of a second semiconductor material having a second band gap value, the second band gap value being strictly greater than the first band gap value; and

a reading circuit delimited in the stacking direction by the first face;

the absorbing layer comprising a first portion having a doping of a first type chosen from among n-type doping and p-type doping, and a second portion having a doping of a second type chosen from among n-type doping and p-type doping, the second type of doping being different from the first type of doping, the first portion and the second portion forming a first p-n junction;

further delimiting a primary hole traversing each of the layers of the stack, the primary hole receiving at least part of a primary electrode electrically connecting the second portion to the reading circuit and traversing the first face, the first p-n junction surrounding the primary electrode in a plane orthogonal to the stacking direction, and

the second face carrying at least one band delimited in the stacking direction by the barrier layer, the band being made from the second semiconductor material and having a doping of the first type and a free carrier density greater than or equal to 1.10¹⁷ cm<sup>−

3</sup>.

2. The radiation detector element according to claim 1, wherein the band is made from a degenerated semiconductor material.

3. The radiation detector element according to claim 1, wherein the band surrounds the primary electrode in a plane orthogonal to the stacking direction.

4. The radiation detector element according to claim 1, wherein the stack further comprises at least one intermediate layer made from a third semiconductor material having a third band gap value comprised between the first band gap value and the second band gap value, the intermediate layer being delimited, in the stacking direction, by the absorbing layer and the barrier layer.

5. The radiation detector element according to claim 4, wherein the third material is a quaternary material at least formed from the first material and the second material.

6. The radiation detector element according to claim 1, wherein the first material is chosen from among InGaAs, InAsSb and InSb, and

when the first material is InGaAs, the second material is InP;

when the first material is InAsSb, the second material is AlGaAsSb; and

when the first material is InSb, the second material is InAlSb.

7. The radiation detector element according to claim 1, further including a passivation layer surrounding the primary electrode in a plane orthogonal to the stacking direction, the passivation layer being delimited in the plane orthogonal to the stacking direction by the primary electrode and by the barrier layer, the passivation layer being able to electrically isolate the barrier layer from the primary electrode.

8. The radiation detector element according to claim 1, further including a filtering layer able to allow the propagation of at least one electromagnetic wave having a first energy comprised in a primary set of energies and to prevent the propagation of at least one electromagnetic wave having a second energy comprised in a secondary set of energies, the secondary set being different from the primary set, the filtering layer being delimited in the stacking direction by the second face.

9. The radiation detection element according to claim 1, wherein the primary hole is cone-shaped with a circular base.

10. An imager comprising at least one second set (E2) of radiation detector elements according to claim 1,

wherein each band is electrically connected to at least one other band, the bands forming, on the second face, a two-dimensional array having a plurality of meshes, each mesh surrounding, in a plane orthogonal to the stacking direction, a single primary electrode.

11. The imager according to claim 10, wherein the array comprises a collection layer made from the second material, and partly covering the second face, the imager further comprising a first set of secondary holes, each secondary hole traversing the collection layer and at least partially receiving a secondary electrode traversing the first face and electrically connecting the collection layer to the reading circuit.

12. The radiation detector element according to claim 2, wherein the band surrounds the primary electrode in a plane orthogonal to the stacking direction.

13. The radiation detector element according to claim 2, wherein the stack further comprises at least one intermediate layer made from a third semiconductor material having a third band gap value comprised between the first band gap value and the second band gap value, the intermediate layer being delimited, in the stacking direction, by the absorbing layer and the barrier layer.

14. The radiation detector element according to claim 3, wherein the stack further comprises at least one intermediate layer made from a third semiconductor material having a third band gap value comprised between the first band gap value and the second band gap value, the intermediate layer being delimited, in the stacking direction, by the absorbing layer and the barrier layer.

15. The radiation detector element according to claim 2, wherein the first material is chosen from among InGaAs, InAsSb and InSb, and

when the first material is InGaAs, the second material is InP;

when the first material is InAsSb, the second material is AlGaAsSb; and

when the first material is InSb, the second material is InAlSb.

16. The radiation detector element according to claim 3, wherein the first material is chosen from among InGaAs, InAsSb and InSb, and

when the first material is InGaAs, the second material is InP;

when the first material is InAsSb, the second material is AlGaAsSb; and

when the first material is InSb, the second material is InAlSb.

17. The radiation detector element according to claim 4, wherein the first material is chosen from among InGaAs, InAsSb and InSb, and

when the first material is InGaAs, the second material is InP;

when the first material is InAsSb, the second material is AlGaAsSb; and

when the first material is InSb, the second material is InAlSb.

18. The radiation detector element according to claim 5, wherein the first material is chosen from among InGaAs, InAsSb and InSb, and

when the first material is InGaAs, the second material is InP;

when the first material is InAsSb, the second material is AlGaAsSb; and

when the first material is InSb, the second material is InAlSb.

19. The radiation detector element according to claim 2, further including a passivation layer surrounding the primary electrode in a plane orthogonal to the stacking direction, the passivation layer being delimited in the plane orthogonal to the stacking direction by the primary electrode and by the barrier layer, the passivation layer being able to electrically isolate the barrier layer from the primary electrode.

20. The radiation detector element according to claim 3, further including a passivation layer surrounding the primary electrode in a plane orthogonal to the stacking direction, the passivation layer being delimited in the plane orthogonal to the stacking direction by the primary electrode and by the barrier layer, the passivation layer being able to electrically isolate the barrier layer from the primary electrode.