TENSILE STRAINED SEMICONDUCTOR PHOTON EMISSION AND DETECTION DEVICES AND INTEGRATED PHOTONICS SYSTEM

• US 20130039664A1
• Filed: 08/12/2011
• Published: 02/14/2013
• Est. Priority Date: 08/12/2011
• Status: Active Grant

• Current Assignee: Acorn Semi, LLC (Acorn Technologies, Inc.)
• Original Assignee: Acorn Technologies, Inc.
• Inventors: Goebel, Andreas, Gaines, R. Stockton, Clifton, Paul A.
• Granted Patent: US 8,731,017 B2
• Time in Patent Office: Days
• US Class Current: 398/200
• CPC Class Codes: B82Y 20/00 Nanooptics, e.g. quantum optics or photonic crystals
• CPC Class Codes: H01L 27/14625 Optical elements or arrangements associated with the device
• CPC Class Codes: H01L 27/14643 Photodiode arrays; MOS imagers
• CPC Class Codes: H01L 31/028 including, apart from doping material or other impurities, only elements of Group IV of the Periodic Table
• CPC Class Codes: H01L 31/0352 characterised by their shape or by the shapes, relative sizes or disposition of the semiconductor regions
• CPC Class Codes: H01L 31/1808 including only Ge
• CPC Class Codes: H01L 33/34 containing only elements of Group IV of the Periodic Table
• CPC Class Codes: H01S 5/125 Distributed Bragg reflector [DBR] lasers
• CPC Class Codes: H01S 5/187 using Bragg reflection
• CPC Class Codes: H01S 5/2203 with a transverse junction stripe [TJS] structure
• CPC Class Codes: H01S 5/227 Buried mesa structure ; Striped active layer
• CPC Class Codes: H01S 5/3201 incorporating bulkstrain effects, e.g. strain compensation, strain related to polarisation
• CPC Class Codes: H01S 5/3223 IV compounds
• CPC Class Codes: H01S 5/3224 Si
• CPC Class Codes: H01S 5/3427 in IV compounds

Abstract

Tensile strained germanium is provided that can be sufficiently strained to provide a nearly direct band gap material or a direct band gap material. Compressively stressed or tensile stressed stressor materials in contact with germanium regions induce uniaxial or biaxial tensile strain in the germanium regions. Stressor materials may include silicon nitride or silicon germanium. The resulting strained germanium structure can be used to emit or detect photons including, for example, generating photons within a resonant cavity to provide a laser.

Claims

1. An optical device comprising:

a germanium region, the germanium region in contact with a plurality of stressor regions, the plurality of stressor regions inducing tensile strain within the germanium region, the tensile strain in at least a portion of the germanium region sufficient to cause the portion of the germanium region to have a direct band gap;

a junction positioned in or adjacent the portion of the germanium region, the junction having a first side with a first majority carrier type and a second side with a second majority carrier type; and

first and second contacts respectively coupled to the first side of the junction and the second side of the junction.

2. The optical device of claim 1, wherein the stressor regions comprise compressively stressed material.

3. The optical device of claim 2, wherein the stressor regions comprise silicon nitride.

4. The optical device of claim 1, wherein the stressor regions are positioned on opposite sides of the germanium region.

5. The optical device of claim 1, wherein the stressor regions are tensile stressed.

6. The optical device of claim 5, wherein the stressor regions are silicon germanium.

7. The optical device of claim 1, wherein first and second stressor regions are positioned on one side of a germanium fin and third and fourth stressor regions are positioned on an opposite side of the germanium fin and wherein the germanium fin comprises the germanium optically active region.

8. The optical device of claim 7, wherein the first, second, third and fourth stressor regions comprise silicon nitride.

9. The optical device of claim 1, wherein a first of the stressor regions is between the germanium optically active region and a substrate and wherein another of the stressor regions is on an opposite side of the germanium optically active region from the first of the stressor regions.

10. An optical device comprising:

first and second germanium regions, the first germanium optically active region in contact with a first tensile stressor so that the first germanium region has biaxial tensile strain in at least a first portion of the first germanium region, the second germanium region in contact with a second tensile stressor so that the second germanium region has biaxial tensile strain in at least a second portion of the second germanium region;

optical elements defining an optical path through the first and second germanium regions;

a junction positioned in or adjacent the first and second portions of the first and second germanium regions, the junction having a first side with a first majority carrier type and a second side with a second majority carrier type; and

first and second contacts respectively coupled to the first side of the junction and the second side of the junction.

11. The optical device of claim 10, wherein the first germanium region has biaxial tensile strain in at least a portion of the first germanium region sufficient to cause the first portion of the first germanium region to have a direct band gap.

12. The optical device of claim 11, wherein the first and second tensile stressors are silicon germanium.

13. The optical device of claim 10, wherein the optical elements include a first mirror and a second mirror that define a laser cavity.

14. The optical device of claim 13, wherein the first mirror and the second mirror are formed on end faces of the laser cavity and wherein the laser cavity is coupled to the first and second germanium regions through evanescent coupling.

15. The optical device of claim 14, wherein the laser cavity is disposed at least partially within a waveguide.

16. The optical device of claim 14, wherein the laser cavity is disposed at least partially within a silicon or silicon oxide waveguide.

17. An optical device comprising:

a germanium slab having first and second faces and first and second ends;

first and second stressor layers on the first and second faces, the first and second stressor layers inducing biaxial tensile stress within the germanium slab; and

optical elements positioned with respect to the germanium slab to define an optical path passing through the germanium slab.

18. The optical device of claim 17, wherein the first and second faces are lateral faces extending above a germanium substrate.

19. The optical device of claim 18, wherein the germanium slab has a thickness of between about 20 nanometer and 100 nanometer and wherein the stressor layers are silicon nitride.

20. The optical device of claim 18, wherein the germanium slab has a thickness of between about 40 nanometer and 80 nanometer, wherein the germanium slab has a width of less than one micron and wherein the stressor layers are silicon nitride.

21. The optical device of claim 18, wherein the germanium slab has a thickness of between about 40 nanometer and 80 nanometer, wherein the germanium slab has a width of less than 400 nanometer and a height of less than 400 nanometer and wherein the stressor layers are silicon nitride.

22. An optical device comprising:

two or more germanium slabs each having first and second faces and first and second ends;

first and second stressor layers on each of the first and second faces, the first and second stressor layers inducing biaxial tensile stress within respective ones of the two or more germanium slabs; and

optical elements positioned with respect to the germanium slabs to define an optical path passing through the two or more germanium slabs.

23. The optical device of claim 22, wherein each of the first and second faces is a lateral face extending above a germanium substrate and the optical path passes through each of the first faces.

24. The optical device of claim 22, wherein each of the first and second faces is a lateral face extending above a germanium substrate and each of the first faces is parallel to the optical path.

25. The optical device of claim 22, wherein the two or more germanium slabs have a thickness of between about 20 nanometer and 100 nanometer and wherein the stressor layers are silicon nitride.

26. The optical device of claim 22, wherein the two or more germanium slabs have a thickness of between about 40 nanometer and 80 nanometer, wherein two or more germanium slabs have a width of less than one micron and wherein the stressor layers are silicon nitride.

27. The optical device of claim 22, wherein the two or more germanium slabs have a thickness of between about 40 nanometer and 80 nanometer, wherein the two or more germanium slabs have a width of less than 400 nanometer and a height of less than 400 nanometer and wherein the stressor layers are silicon nitride.

28. A method of making an optical device, comprising:

providing a substrate having a germanium region;

etching openings into the germanium region; and

forming silicon germanium within the openings to form a pattern of embedded silicon germanium regions surrounding a first portion of the germanium region, and the first portion of the germanium region having in-plane biaxial tensile strain.

29. The method of claim 28, wherein the germanium region is a germanium layer separated from another portion of the substrate by an insulating layer.

30. The method of claim 28, wherein the method forms at least four additional portions of the germanium region having biaxial tensile strain.

31. The method of claim 30, wherein biaxial tensile strain within the first and additional germanium portions is sufficient in at least parts of the germanium portions to provide a direct bandgap.

32. The method of claim 30, further comprising forming a laser cavity so that light amplified within the laser cavity passes through the first portion of the germanium region and at least one additional portion of the germanium region.

33. The method of claim 28, wherein tensile strain within the first portion of the germanium region is sufficient in at least a part of the first germanium region to provide a direct bandgap.

34. The method of claim 33, further comprising forming a laser cavity so that light amplified within the laser cavity passes through the first portion of the germanium region.

35. A method of communicating data, comprising coupling an electrical signal into a optical device comprising a first strained semiconductor region to generate a responsive optical signal, transmitting the responsive optical signal through a waveguide comprising a second unstrained semiconductor region and coupling the responsive optical signal into a detector comprising a third strained semiconductor region, wherein the first, second and third semiconductor regions comprise germanium.

36. The method of claim 35, wherein the first and third semiconductor regions are in-plane biaxially strained germanium in contact with silicon germanium stressor regions.

37. The method of claim 36, wherein the first, second and third semiconductor regions are essentially self-aligned with each other.