Light emitting devices with improved extraction efficiency

A light-emitting device, comprising:

• a multi-layer stack of materials including a light-generating region and a first layer supported by the light-generating region, a surface of the first layer being configured so that light generated by the light-generating region can emerge from the light-emitting device via the surface of the first layer, and the surface of the first layer has a dielectric function that varies spatially according to a pattern;
• and
• a layer of reflective material that is capable of reflecting at least about 50% of light generated by the light-generating region that impinges on the layer of reflective material,
• wherein the light-generating region is between the layer of reflective material and the first layer, the pattern does not extend beyond the first layer in the direction of the light generating region, and the pattern does not extend into the light-generating region.

A light-emitting device, comprising:

• a multi-layer stack of materials including a layer of n-doped material, a layer of p-doped material, and a light-generating region;
• and
• a layer of reflective material that is capable of reflecting at least about 50% of light generated by the light-generating region that impinges on the layer of reflective material,
• wherein:
• a surface of the layer of n-doped material is configured so that light generated by the light-generating region can emerge from the light-emitting device via the surface of the layer of n-doped material;
• the surface of the layer of n-doped material has a dielectric function that varies spatially according to a pattern;
• a distance between the layer of p-doped material and the layer of reflective material is less than a distance between the layer of n-doped material and the layer of reflective material;
• and
• the pattern of variation is selected from the group consisting of nonperiodic patterns, complex periodic patterns, and patterns having an ideal lattice constant and a detuning parameter greater than zero.

A light-emitting device, comprising:

• a multi-layer stack of materials including a light-generating region and a first layer supported by the light-generating region, a surface of the first layer being configured so that light generated by the light-generating region can emerge from the light-emitting device via the surface of the first layer, and the surface of the first layer has a dielectric function that varies spatially according to a pattern;
• and
• a layer of reflective material that is capable of reflecting at least about 50% of light generated by the light-generating region that impinges on the layer of reflective material,
• wherein:
• the light-generating region is between the layer of reflective material and the first layer;
• the pattern does not extend beyond the first layer;
• and
• the pattern comprises at least one pattern selected from the group consisting of nonperiodic patterns, complex periodic patterns and patterns having an ideal lattice constant and a detuning parameter greater than zero.