Grown photonic crystals in semiconductor light emitting devices

A device comprising:

• a semiconductor structure comprising a light emitting layer configured to emit light of wavelength λ, the light emitting layer being disposed between an n-type region and a p-type region, the semiconductor structure having a top surface and a bottom surface;
• and
• a photonic crystal disposed within the semiconductor structure, the photonic crystal comprising:
• a plurality of posts of semiconductor material having a first refractive index arranged in an array, each post being located less than 5λ from a nearest neighbor post;
• and
• a region of a material having a second refractive index surrounding the posts, wherein the second refractive index is different from the first refractive index, the region of material having a second refractive index having a first end and a second end opposite the first end;
• wherein the first end of the region of the material having a second refractive index comprises inverted pyramids that connect to form a planar semiconductor layer over the plurality of posts and the region of the material having a second refractive index, and the second end of the region of the material having a second refractive index comprises a mask layer disposed between the posts;
• wherein the region of the material having a second refractive index does not extend to the top surface or the bottom surface such that the top surface and the bottom surface of the semiconductor structure are uninterrupted by the photonic crystal, and wherein the top surface and the bottom surface are continuous, planar surfaces.