Photodiode array structure for cross talk suppression

Patent metadata

Field	Value
Publication number	US-10109671-B2
Application number	US-201715602572-A
Country	US
Kind code	B2
Filing date	May 23, 2017
Priority date	May 23, 2016
Publication date	Oct 23, 2018
Grant date	Oct 23, 2018

Abstract

There is provided an avalanche photodiode array that includes a plurality of avalanche photodiodes. Each avalanche photodiode in the array includes a stack of active photodiode materials. The stack of active photodiode materials includes a first electrical contact layer, a second electrical contact layer; an absorber material layer and an avalanche material layer each disposed between the first electrical contact layer and the second electrical contact layer; and an optical interface surface to the avalanche photodiode. The optical interface surface consists of an exposed surface of the first electrical contact layer, arranged for incident external radiation to directly enter the first electrical contact layer. Each avalanche photodiode stack of active photodiode materials is laterally isolated from the other avalanche photodiodes in the photodiode array.

First claim

We claim:

1. An avalanche photodiode array comprising:
a plurality of avalanche photodiodes, each avalanche photodiode including a stack of active photodiode materials comprising:
a first electrical contact layer;
a second electrical contact layer;
an absorber material layer and an avalanche material layer each disposed between the first electrical contact layer and the second electrical contact layer; and
an optical interface surface to the avalanche photodiode, the optical interface surface consisting of an exposed surface of the first electrical contact layer, arranged for incident external radiation to directly enter the first electrical contact layer and coated with an antireflection coating to facilitate entrance of external incident radiation into the first electrical contact layer; and

wherein each avalanche photodiode stack of active photodiode materials is laterally isolated from the other avalanche photodiodes in the photodiode array.

2. The avalanche photodiode array of claim 1 further comprising a cross talk blocking region disposed laterally adjacent to each avalanche photodiode in the array, between laterally isolated stacks of active photodiode material, maintaining an exposed surface of the first electrical contact layer of each avalanche photodiode in the array, the cross talk blocking region comprising a cross talk blocking material that exhibits a condition selected from the group consisting of absorption of secondary photons produced by avalanche photodiodes in the array and reflection of secondary photons produced by avalanche photodiodes in the array.

3. The avalanche photodiode array of claim 2 wherein the cross talk blocking region is electrically conducting and is in electrical contact with the exposed surface of the first electrical contact layer of each avalanche photodiode in the array.

4. The avalanche photodiode array of claim 3 wherein the cross talk blocking material layer comprises a metal layer.

5. The avalanche photodiode array of claim 3 wherein the cross talk blocking material layer comprises a doped semiconducting layer.

6. The avalanche photodiode array of claim 2 wherein the cross talk blocking region comprises a material layer that laterally overlaps edges of the exposed surface of the first electrical contact layer of each avalanche photodiode in the array.

7. The avalanche photodiode array of claim 2 wherein the cross talk blocking region comprises a cross talk blocking passivation layer disposed on sidewalls of each avalanche photodiode stack of active photodiode materials.

8. The avalanche photodiode array of claim 2 wherein the cross talk blocking region comprises a cross talk blocking underfill material that is disposed between each avalanche photodiode stack of active photodiode materials.

9. The avalanche photodiode array of claim 2 wherein the cross talk blocking region comprises a cross talk blocking layer extending down a sidewall of each avalanche photodiode stack of active photodiode materials.

10. The avalanche photodiode array of claim 9 wherein the cross talk blocking layer comprises an electrically conducting material layer in each avalanche photodiode that makes an electrical connection to the first electrical contact layer of that avalanche photodiode.

11. The avalanche photodiode array of claim 2 further comprising a passivation layer disposed on sidewalls of each avalanche photodiode stack of active photodiode materials, and wherein the cross talk blocking region comprises a cross talk blocking layer that is disposed on the passivation layer.

12. The avalanche photodiode array of claim 11 wherein the passivation layer includes an aperture between each avalanche photodiode stack of active photodiode materials, and wherein the crosstalk blocking layer disposed on the passivation layer fills each aperture.

13. The avalanche photodiode array of claim 1 further comprising an electrically conducting electrical contact layer disposed laterally adjacent to each avalanche photodiode in the array, between laterally isolated stacks of active photodiode material, maintaining an exposed surface of and making electrical contact to the first electrical contact layer of each avalanche photodiode in the array.

14. The avalanche photodiode array of claim 1 further comprising an array of microlenses, each microlens disposed in an optical path with the optical interface surface of an avalanche photodiode in the array of avalanche photodiodes for focusing incident external radiation to the exposed surface of the first electrical contact layer of each avalanche photodiode in the array of avalanche photodiodes.

15. The avalanche photodiode array of claim 14 , further comprising a cross talk blocking region disposed laterally adjacent to each avalanche photodiode in the array, between laterally isolated stacks of active photodiode material, maintaining an exposed surface of the first electrical contact layer of each avalanche photodiode in the array, the cross talk blocking region comprising a cross talk blocking material that exhibits a condition selected from the group consisting of absorption of secondary photons produced by avalanche photodiodes in the array and reflection of secondary photons produced by avalanche photodiodes in the array, and wherein the array of microlenses is disposed adjacent to the cross talk region for focusing incident external radiation to the exposed surface of the first electrical contact layer of each avalanche photodiode in the array.

16. The avalanche photodiode array of claim 1 further comprising:
a cross talk blocking region disposed laterally adjacent to each avalanche photodiode in the array, between laterally isolated stacks of active photodiode material, maintaining an exposed surface of the first electrical contact layer of each avalanche photodiode in the array, the cross talk blocking region comprising a cross talk blocking material that exhibits a condition selected from the group consisting of absorption of secondary photons produced by avalanche photodiodes in the array and reflection of secondary photons produced by avalanche photodiodes in the array;
a passivation layer disposed on sidewalls of each avalanche photodiode stack of active photodiode materials; and
an underfill material disposed between each avalanche photodiode stack of active photodiode materials, over the passivation layer;
wherein at least one of the passivation layer and the underfill material comprises a cross talk blocking material that exhibits a condition selected from the group consisting of absorption of secondary photons produced by avalanche photodiodes in the array and reflection of secondary photons produced by avalanche photodiodes in the array.

17. The avalanche photodiode array of claim 16 wherein the cross talk blocking region comprises a cross talk blocking material layer that makes electrical connection to the first electrical contact layer of each avalanche photodiode in the array.

18. The avalanche photodiode array of claim 17 further comprising an array of microlenses, each microlens disposed adjacent to the cross talk blocking material layer, in an optical path with the optical interface surface of an avalanche photodiode in the array of avalanche photodiodes, for focusing incident external radiation to the exposed surface of the first electrical contact layer of each avalanche photodiode in the array of avalanche photodiodes.

19. An avalanche photodiode array comprising:
a plurality of avalanche photodiodes, each avalanche photodiode including a stack

Assignees

• Donnelly Joseph P
• Mcintosh K Alexander
• Duerr Erik K
• Goodhue William D
• Bailey Robert J
• Wright Lisa A
• Massachusetts Inst Technology

Inventors

• Donnelly Joseph P
• Mcintosh K Alexander
• Duerr Erik K
• Goodhue William D
• Bailey Robert J
• Wright Lisa A

Classifications

• G01J1/0214

  Constructional arrangements for removing stray light · CPC title

• G01J1/06

  Restricting the angle of incident light · CPC title

• G01J1/0411

  using focussing or collimating elements, i.e. lenses or mirrors; Aberration correction · CPC title

• G01J2001/4466

  Avalanche · CPC title

• G01J1/0437

  using masks, aperture plates, spatial light modulators, spatial filters, e.g. reflective filters · CPC title