LIGHT EMITTING DEVICE INCLUDING A PHOTONIC CRYSTAL AND A LUMINESCENT CERAMIC

1 . A device comprising:

a semiconductor structure comprising:

a light emitting layer disposed between an n-type region and a p-type region; and

a repeating variation in refractive index formed within or on a surface of the semiconductor structure, wherein the refractive index varies in a direction parallel to a major surface of the light emitting layer; and

a ceramic layer disposed in a path of light emitted by the light emitting layer, the ceramic layer comprising a wavelength converting material, the ceramic layer comprising a self-supporting slab, wherein a surface of the ceramic layer is textured.

2 . The device of claim 1 wherein the ceramic layer comprises a rigid agglomerate of phosphor particles.

3 - 4 . (canceled)

5 . The device of claim 1 wherein the variation in refractive index comprises a periodic arrangement of features, wherein the arrangement of features has a period more than twice a peak emission wavelength of the light emitting layer.

6 . (canceled)

7 . The device of claim 1 wherein the variation in refractive index is a photonic crystal.

8 . The device of claim 7 wherein the photonic crystal comprises a periodic variation in a thickness of the n-type region.

9 . The device of claim 7 wherein the photonic crystal comprises a planar lattice of holes.

10 . The device of claim 7 wherein a distance between a center of the light emitting layer and the photonic crystal is less than about 4λ, where λ is a wavelength in the semiconductor structure of light emitted by the light emitting layer.

11 . The device of claim 1 wherein a total thickness of semiconductor layers in the device is less than about 1 μm.

12 - 14 . (canceled)

15 . The device of claim 1 further comprising a host substrate, wherein the semiconductor structure is attached to the host substrate and the ceramic layer is disposed proximate a surface of the semiconductor structure opposite the host substrate.

16 . The device of claim 1 wherein the wavelength converting material comprises one of (Lu 1-x-y-a-b Y x Gd y ) 3 (Al 1-z Ga z ) 5 O 12 :Ce a Pr b wherein 0<x<1, 0<y<1, 0<z≦0.1, 0<a≦0.2 and 0<b≦0.1; Lu 3 Al 5 O 12 :Ce 3+ ; and Y 3 Al 5 O 12 :Ce 3+ .

17 . The device of claim 1 further comprising a light valve disposed between the semiconductor structure and the ceramic layer.

18 . (canceled)

19 . The device of claim 17 wherein the variation in refractive index is configured to emit light in a predetermined angular emission profile and wherein the light valve is configured to transmit a majority of light emitted in the predetermined emission profile and incident on the light valve.

20 . The device of claim 19 wherein more than 60% of light escaping the semiconductor structure is emitted into a cone 45° from a normal to a major surface of the semiconductor structure and more than 90% of the light emitted into the 45° cone is transmitted by the light valve.

21 . The device of claim 20 wherein less than 10% of the light emitted by the ceramic is transmitted by the light valve.

22 . The device of claim 17 wherein the light valve is spaced apart from the semiconductor structure.

23 . The device of claim 17 further comprising a transparent material disposed between the light valve and the semiconductor structure, wherein the transparent material has an index of refraction greater than 1.4.

24 . The device of claim 17 further comprising a dielectric concentrator disposed in a path of light emitted by the light emitting layer.

25 . The device of claim 24 wherein the ceramic layer is disposed between the dielectric concentrator and the semiconductor structure.

26 . The device of claim 24 wherein the dielectric concentrator is disposed between the semiconductor structure and the ceramic layer.

27 - 33 . (canceled)

34 . The device of claim 1 wherein the ceramic layer is attached to the semiconductor structure by an adhesive.