LOW-VOLTAGE HIGH-GAIN HIGH-SPEED GERMANIUM PHOTO DETECTOR AND METHOD OF FABRICATING THE SAME

• US 20140048772A1
• Filed: 07/23/2013
• Published: 02/20/2014
• Est. Priority Date: 08/20/2012
• Status: Active Grant

• Current Assignee: Electronics and Telecommunications Research Institute
• Original Assignee: Electronics and Telecommunications Research Institute
• Inventors: KIM, Gyungock, KIM, Sang Hoon, JANG, Ki Seok, KIM, In Gyoo, OH, Jin Hyuk, KIM, Sun Ae
• Granted Patent: US 9,171,996 B2
• Time in Patent Office: Days
• US Class Current: 257/21
• CPC Class Codes: B82Y 20/00 Nanooptics, e.g. quantum optics or photonic crystals
• CPC Class Codes: H01L 31/035227 the quantum structure being quantum wires, or nanorods carbon nanotubes H10K85/211
• CPC Class Codes: H01L 31/035254 including, apart from doping materials or other impurities, only elements of Group IV of the Periodic Table, e.g. Si-SiGe superlattices
• CPC Class Codes: H01L 31/107 the potential barrier working in avalanche mode, e.g. avalanche photodiodes
• CPC Class Codes: H01L 33/0054 for devices with an active region comprising only group IV elements
• CPC Class Codes: H01L 33/06 within the light emitting region, e.g. quantum confinement structure or tunnel barrier
• CPC Class Codes: Y10S 977/762 Nanowire or quantum wire, i.e. axially elongated structure having two dimensions of 100 nm or less
• CPC Class Codes: Y10S 977/774 Exhibiting three-dimensional carrier confinement, e.g. quantum dots
• CPC Class Codes: Y10S 977/954 Of radiant energy

Abstract

Provided is a silicon-wafer-based germanium semiconductor photodetector configured to be able to provide properties of high gain, high sensitivity, and high speed, at a relatively low voltage. A germanium-based carrier multiplication layer (e.g., a single germanium layer or a germanium and silicon superlattice layer) may be provided on a silicon wafer, and a germanium charge layer may be provided thereon, a germanium absorption layer may be provided on the charge layer, and a polysilicon second contact layer may be provided on the absorption layer. The absorption layer may be configured to include germanium quantum dots or wires.

Claims

1. A photodetector, comprising:

a silicon substrate;

a first contact layer on the substrate;

a carrier multiplication layer on the first contact layer;

a charge layer on the carrier multiplication layer;

an absorption layer on the charge layer; and

a second contact layer on the absorption layer,

wherein the carrier multiplication layer, the charge layer, and the absorption layer comprises germanium.

2. The photodetector of claim 1, wherein the absorption layer comprises intrinsic germanium.

3. The photodetector of claim 1, wherein the carrier multiplication layer comprises intrinsic germanium.

4. The photodetector of claim 1, wherein the first contact layer is doped with first impurities.

5. The photodetector of claim 4, wherein the charge layer is doped with second impurities, whose conductivity type is opposite to the first impurities.

6. The photodetector of claim 5, wherein the second contact layer is doped with the second impurities.

7. The photodetector of claim 5, wherein the second contact layer comprises germanium.

8. The photodetector of claim 5, wherein the second contact layer comprises polysilicon.

9. The photodetector of claim 1, wherein the first contact layer comprises silicon.

10. The photodetector of claim 1, wherein the carrier multiplication layer comprises a germanium and silicon superlattice.

11. The photodetector of claim 1, wherein the absorption layer comprises a germanium and silicon superlattice.

12. The photodetector of claim 1, further comprising, a buried oxide layer between the substrate and the first contact layer.

13. The photodetector of claim 1, wherein the absorption layer comprises a germanium and silicon superlattice.

14. The photodetector of claim 1, wherein the absorption layer comprises at least one quantum dot structure or at least one quantum wire structure.

15. The photodetector of claim 1, wherein the absorption layer comprises a germanium and silicon superlattice layer and an intrinsic germanium layer.

16. The photodetector of claim 1, further comprising, a floating guard ring provided adjacent to the charge layer.

17. A method of fabricating a photodetector, comprising:

forming a first contact layer on a substrate;

forming a carrier multiplication layer on the first contact layer;

forming a charge layer on the carrier multiplication layer; and

forming an absorption layer on the charge layer,

wherein all of the carrier multiplication layer, the first contact layer, and the charge layer comprise germanium and are formed in an in-situ manner in one chamber or cluster.

18. The method of claim 17, wherein the first contact layer is formed of a silicon layer doped with first impurities.

19. The method of claim 18, further comprising, forming a second contact layer on the absorption layer.

20. The method of claim 19, wherein the second contact layer is formed of a poly silicon layer doped with second impurities.