Semiconductor light emitting devices including current spreading layers

1. A semiconductor light emitting device comprising:

a light emitting region disposed between a cladding region of first conductivity type and a cladding region of second conductivity type;

a contact region of first conductivity type adjacent to the cladding region of first conductivity type;

a contact region of second conductivity type adjacent to the cladding region of second conductivity type; and

at least one heavily doped layer disposed within the cladding region of first conductivity type, wherein the heavily doped layer is more heavily doped than the cladding region of first conductivity type.

2. The device of claim 1 wherein the light emitting region comprises at least one layer of InGaP.

3. The device of claim 1 wherein the light emitting region comprises at least one layer of InGaN.

4. The device of claim 1 further comprising a plurality of heavily doped layers disposed within the cladding region of first conductivity type.

5. The device of claim 4 wherein:

each of the plurality of heavily doped layers is between about 10 nm and about 100 nm thick; and

the plurality of heavily doped layers are separated by at least 10 nm of cladding region of first conductivity type.

6. The device of claim 4 wherein a total thickness of the plurality of heavily doped layers is between about 100 nm and about 500 nm.

7. The device of claim 1 wherein:

the cladding region of first conductivity type has a dopant concentration between about 5×10 17 and about 1×10 18 cm −3 ; and

the heavily doped layer has a dopant concentration between about 1×10 18 and about 1×10 19 cm −3 .

8. The device of claim 1 wherein the heavily doped layer comprises (Al x Ga 1-x ) 0.5 In 0.5 P, where 0<x≧1.

9. The device of claim 8 wherein the heavily doped layer comprises (Al x Ga 1-x ) 0.5 In 0.5 P, where 0.2<x<0.7.

10. The device of claim 8 wherein the heavily doped layer comprises (Al 0.65 Ga 0.35 ) 0.5 In 0.5 P.

11. The device of claim 1 wherein the heavily doped layer comprises Al x In y Ga z N, where 0<x≦1, 0<y≦1, and 0<z≦1.

12. The device of claim 1 wherein the heavily doped layer comprises GaN.

13. The device of claim 1 wherein the heavily doped layer is a first heavily doped layer, the device further comprising a second heavily doped layer disposed within the cladding region of second conductivity type, wherein the second heavily doped layer is more heavily doped than the cladding region of second conductivity type.

14. The device claim 1 wherein the heavily doped layer is a first heavily doped layer disposed within the cladding region of first conductivity type, the device further comprising a second heavily doped layer disposed within the contact region of first conductivity type, wherein the second heavily doped layer is more heavily doped than the contact region of first conductivity type.

15. The device claim 1 wherein the heavily doped layer is a first heavily doped layer disposed within the cladding region of first conductivity type, the device further comprising a second heavily doped layer disposed within the contact region of first conductivity type, wherein the second heavily doped layer is more heavily doped than the contact region of first conductivity type.

16. The device of claim 1 further comprising:

a first lead electrically connected to the cladding region of first conductivity type;

a second lead electrically connected to the cladding region of second conductivity type; and

a cover disposed over the light emitting region.

17. A semiconductor light emitting device comprising:

a light emitting region disposed between a cladding region of first conductivity type and a cladding region of second conductivity type;

a contact region of first conductivity type adjacent to the cladding region of first conductivity type;

a contact region of second conductivity type adjacent to the cladding region of second conductivity type;

at least one heavily doped layer disposed within the contact region of first conductivity type, wherein the heavily doped layer is more heavily doped than the contact region of first conductivity type;

wherein:

the contact region of first conductivity type is spaced apart from the light emitting region by the cladding region of first conductivity type; and

the contact region of second conductivity type is spaced apart from the light emitting region by the cladding region of second conductivity type.

18. The device of claim 17 the heavily doped layer is a first heavily doped layer disposed within the contact region of first conductivity type, the device further comprising a second heavily doped layer disposed within the contact region of second conductivity type, wherein the second heavily doped layer is more heavily doped than the contact region of second conductivity type.