Light emitting semiconductor device having an electrical confinement barrier near the active region

• US 7,920,612 B2
• Filed: 07/31/2006
• Issued: 04/05/2011
• 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: Biard, James R., Johnson, Ralph H., Guenter, James K.
• Primary Examiner(s): Harvey; Minsun
• Assistant Examiner(s): CARTER, MICHAEL W
• Application Number:
  US11/461,353
• Publication Number:
  US 20060268954A1
• Time in Patent Office: 1,709 Days
• Field of Search: 372/45.01, 372/50.124
• US Class Current: 372/45.01
• 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 III-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 comprising aluminum;

a confinement barrier positioned between the spacer layer and the active region and having a thickness that is in a range from 2 nm to 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, wherein the electrical confining layer comprises a dopant increase in the confinement barrier, the spacer layer comprising a direct bandgap material having an aluminum content of less than 45% and wherein the confinement barrier has an aluminum content greater than 60%.

2. 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%.

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 greater than 40%.

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

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

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

7. A semiconductor device as in claim 1, wherein the III-V semiconductor material comprises Al_xGa₁₋

xAs, wherein x is between 0.0 and 1.0.

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

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

10. A light emitting semiconductor device comprising a III-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, wherein the confining layer is on the bottom side of the active region;

a spacer layer comprising a direct bandgap material having an aluminum content less than 45% and greater than an aluminum content of the active region;

a confinement barrier positioned between the spacer layer and the active region and having a thickness that is in a range from 2 nm to 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; and

a second confinement barrier within a confining layer on the upper side of the active region.

11. 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 III-V semiconductor material and being positioned adjacent the active region, the confining layer having,

a spacer layer comprising a direct bandgap material having an aluminum content less than 45% and greater than an aluminum content of the active region;

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, wherein the aluminum content of the confinement barrier is greater than 60%.

12. A semiconductor device as in claim 11, wherein the confinement barrier is on a bottom side of the active region.

13. A semiconductor device as in claim 12, wherein the dopant level is between 5×

10¹⁷/cm³ to 6×

10¹⁸/cm³ in the confinement barrier.

14. A semiconductor device as in claim 12, wherein the dopant level is between 1×

10¹⁸/cm³ to 3×

10¹⁸/cm³ in the confinement barrier.

15. A semiconductor device as in claim 11, wherein the confining layer is on an upper side of the active region.

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

10¹⁷/cm³ to 1×

10¹⁹/cm³ in the confinement barrier.

17. A semiconductor device as in claim 15, wherein the dopant level is between 1×

10¹⁸/cm³ to 3×

10¹⁸/cm³ in the confinement barrier.

18. A semiconductor device as in claim 11, wherein the aluminum content of the confinement barrier is greater than that of the spacer layer by between 10% and 40%.

19. A semiconductor device as in claim 11, wherein the aluminum content of the confinement barrier is greater than that of the spacer layer by greater than 40%.

20. A semiconductor device as in claim 11, wherein the confining layer is less than 20 nm thick.

26. A semiconductor device as in claim 11, where in the spacer layer is adjacent the upper mirror or the lower mirror and wherein the composition of the spacer layer has the same electron affinity as the composition of at least one layer of the adjacent upper mirror or lower mirror.

21. 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 2 nm to 50 nm, an aluminum content in a range from 60% to 100%, and a dopant level in a range of 5×

10¹⁷/cm³ to 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 wherein the material directly above the first confinement barrier has an aluminum content less than 45% aluminum and greater than the active region, such that the material directly above the first confinement barrier is a direct bandgap material; 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 2 nm to 50 nm, an aluminum content in a range from 60% to 100%, and a dopant level in a range of 5×

10¹⁷/cm³ to 1×

10¹⁹/cm³, and wherein the aluminum content and dopant level of the second confinement barrier is greater than that of the layer directly below the second confinement barrier and wherein the material directly below the second confinement barrier has an aluminum content less than 45% and greater than the active region, such that the material directly below the second confinement barrier is a direct bandgap material.

22. A semiconductor device as in claim 21, wherein the aluminum content of the first and second confinement barriers is greater than that of the material respectively above and below by at least 15%.

23. A semiconductor device as in claim 21, wherein the aluminum content of the first and second confinement barriers is greater than that of the material respectively above and below by at least 30%.

24. A semiconductor device as in claim 21, wherein the semiconductor device is an oxidized laser.

25. A semiconductor device as in claim 21, wherein the dopant level in the first and second confinement barriers is between 1×

10¹⁸/cm³ to 3×

10¹⁸/cm³.