LIGHT EMITTING SEMICONDUCTOR DEVICE HAVING AN ELECTRICAL CONFINEMENT BARRIER NEAR THE ACTIVE REGION

• US 20060268954A1
• Filed: 07/31/2006
• Published: 11/30/2006
• Est. Priority Date: 08/31/2004
• Status: Active Grant

• Current Assignee: II-VI Delaware, Inc. (Coherent Corp.)
• Original Assignee: Finisar Corporation (II-VI Incorporated)
• Inventors: Johnson, Ralph H., Guenter, James K., Biard, James R.
• Granted Patent: US 7,920,612 B2
• Time in Patent Office: Days
• US Class Current: 372/45.10
• CPC Class Codes: B82Y 20/00 Nanooptics, e.g. quantum optics or photonic crystals
• CPC Class Codes: H01L 33/105 with a resonant cavity structure
• CPC Class Codes: H01S 5/18311 using selective oxidation
• CPC Class Codes: H01S 5/18358 containing spacer layers to adjust the phase of the light wave in the cavity
• CPC Class Codes: H01S 5/3054 p-doping
• CPC Class Codes: H01S 5/3211 characterised by special cladding layers, e.g. details on band-discontinuities
• CPC Class Codes: H01S 5/3432 the whole junction comprising only (AI)GaAs

Abstract

Light emitting semiconductor devices such as VCSELs, SELs, and LEDs are manufactured to have a thin electrical confinement barrier in a confining layer near the active region of the device. The thin confinement barrier comprises a III-V semiconductor material having a high aluminum content (e.g. 80%-100% of the type III material). The aluminum content of the adjacent spacer layer is lower than that of the confinement barrier. In one embodiment the spacer layer has an aluminum content of less than 40% and a direct bandgap. The aluminum profile reduces series resistance and improves the efficiency of the semiconductor device.

Claims

1. A light emitting semiconductor device comprising a Ill-V semiconductor material and having improved electrical confinement in the active region, comprising:

an active region;

an electrical confining layer positioned adjacent the active region, the confining layer comprising;

a spacer layer;

a confinement barrier positioned between the spacer layer and the active region and having a thickness that is in a range from about 2 nm to about 50 nm, the confinement barrier having an aluminum content greater than that of the spacer layer, thereby creating a spike in the aluminum content near the active region.

2. A semiconductor device as in claim 1, wherein the electrical confining layer comprises a dopant increase in the confinement barrier.

3. A semiconductor device as in claim 1, wherein the aluminum content of the confinement barrier is greater than that of the spacer layer by between 10% and 40%.

4. A semiconductor device as in claim 1, wherein the aluminum content of the confinement barrier is greater than that of the spacer layer by greater than 40%.

5. A semiconductor device as in claim 1, wherein the aluminum content of the confinement barrier is greater than 80%.

6. A semiconductor device as in claim 1, wherein the thickness of the confinement barrier is in a range from about 5 nm to about 20 nm.

7. A semiconductor device as in claim 1, wherein the thickness of the confinement barrier is between 8 nm and 10 nm.

8. A semiconductor device as in claim 1, wherein the III-IV semiconductor material comprises Al_xGa_1-xAs, wherein x is between 0.0 and 1.0.

9. A semiconductor device as in claim 1, wherein the confining layer is on the upper side of the active region.

10. A semiconductor device as in claim 1, wherein the confining layer is on the bottom side of the active region.

11. A semiconductor device as in claim 10, further comprising a second confinement barrier within a confining layer on the upper side of the active region.

12. A semiconductor device as in claim 1, wherein the spacer layer has a composition that gives it a direct band gap.

13. A semiconductor device having a confinement barrier to improve electron confinement in the active region, comprising:

a substrate; and

an epitaxial structure deposited on the substrate, the epitaxial structure comprising;

a bottom mirror and an upper mirror;

an active region between the bottom mirror and the upper mirror;

a confining layer comprising a Ill-V semiconductor material and being positioned adjacent the active region, the confining layer having,

a spacer layer;

a confinement barrier positioned between the active region and the spacer layer, the confinement barrier having an aluminum content and a dopant level that is greater than that of the spacer layer.

14. A semiconductor device as in claim 13, wherein the confinement barrier is on a bottom side of the active region.

15. A semiconductor device as in claim 14, wherein the dopant level is between about 5×

10¹⁷/cm³ to about 6×

10¹⁸/cm³ in the confinement barrier.

16. A semiconductor device as in claim 14, wherein the dopant level is between about 1×

10¹⁸/cm³ to about 3×

10¹⁸/cm³ in the confinement barrier.

17. A semiconductor device as in claim 13, wherein the confining layer is on an upper side of the active region.

18. A semiconductor device as in claim 17, wherein the dopant level is between about 5×

10¹⁷/cm³ to about 1×

10¹⁹/cm³.

19. A semiconductor device as in claim 17, wherein the dopant level is between about 1×

10¹⁸/cm³ to about 3×

10¹⁸/cm³.

20. A semiconductor device as in claim 13, wherein the aluminum content of the confinement barrier is greater than that of the spacer layer by between 10% and 40%.

21. A semiconductor device as in claim 13, wherein the aluminum content of the confinement barrier is greater than that of the spacer layer by greater than 40%.

22. A semiconductor device as in claim 13, wherein the confining layer is less than about 20 nm thick.

23. A semiconductor device as in claim 13, wherein the aluminum content of the spacer layer is less than 45%.

24. A III-V semiconductor device having a confinement barrier to improve electron confinement in the active region, comprising:

a substrate; and

an epitaxial structure deposited on the substrate, the epitaxial structure comprising;

a bottom mirror and an upper mirror;

an active region between the bottom mirror and the upper mirror;

a first confining layer above the active region, the confining layer comprising a first confinement barrier, the first confinement barrier having a thickness in a range from about 2 nm to about 50 nm, an aluminum content in a range from about 60% to about 100%, and a dopant level in a range of about 5×

10¹⁷/cm³ to about 6×

10¹⁸/cm³, and wherein the aluminum content and dopant level of the first confinement barrier is greater than that of the material directly above the first confinement barrier; and

a second confining layer below the active region, the second confining layer comprising a second confinement barrier, the confinement barrier having a thickness in a range from about 2 nm to about 50 nm, an aluminum content in a range from about 60% to about 100%, and a dopant level in a range of about 5×

10¹⁷/cm³ to about 1×

10¹⁹/cm³, and wherein the aluminum content and dopant level of the confinement barrier is greater than that of the layer directly below the second confinement barrier.

25. A semiconductor device as in claim 24, wherein the aluminum content of the first and second confinement barriers is greater than that of the material respectively above and below by about by at least 15%.

26. A semiconductor device as in claim 24, wherein the aluminum content of the first and second confinement barriers is greater than that of the material respectively above and below by about by at least 30%.

27. A semiconductor device as in claim 24, wherein the semiconductor device is an oxidized laser.

28. A semiconductor device as in claim 24, wherein the dopant level in the first and second confinement barriers is between about 1×

10¹⁸/cm³ to about 3×

10¹⁸/cm³.