Abstract: A light-emitting device (LED) is described which exhibits high extraction efficiency and an emission profile which is substantially more directional than from a Lambertian source. The device comprises a light generating layer disposed between first and second layers of semiconductor material, each having a different type of doping. An upper surface of the first layer has a tiling arrangement of inverted pyramidal or inverted frustro-pyramidal indentations in the semiconductor material filled by a material of different refractive index and which together comprise a photonic band structure. The indentations and their tiling arrangement are configured for efficient extraction of light from the device via the upper surface of the first layer and in a beam that is substantially more directional than from a Lambertian source. An enhanced device employs a reflector beneath the second layer to utilise the microcavity effect.

Abstract: Light emitting diode (LED) structures are described that include a first layer and a light-generating layer, wherein light generated in the light-generating layer generally emerges from the LED structure through the upper surface of the first layer. The coupling out of light generated by spontaneous emission is enhanced by the presence of patterning in the first layer, which may take the form of an embedded photonic quasicrystal, a photonic structure comprising an amorphous array of subregions, or a zone plate structure. The invention provides the benefit of improved light extraction from the LED without undesirable far field illumination patterns.

Abstract: A light-emitting device (LED) is described which exhibits high extraction efficiency and an emission profile which is substantially more directional than from a Lambertian source. The device comprises a light generating layer disposed between first and second layers of semiconductor material, each having a different type of doping. An upper surface of the first layer has a tiling arrangement of pyramidal or frustro-pyramidal protrusions of semiconductor material surrounded by a material of different refractive index which together comprise a photonic band structure. The protrusions and their tiling arrangement are configured for efficient extraction of light from the device via the upper surface of the first layer and in a beam that is substantially more directional than from a Lambertian source An enhanced device employs a reflector beneath the second layer to utilize the microcavity effect.

Abstract: Light emitting diode (LED) structures are described that include a first layer and a light-generating layer, wherein light generated in the light-generating layer generally emerges from the LED structure through the upper surface of the first layer. The coupling out of light generated by spontaneous emission is enhanced by the presence of patterning in the first layer, which may take the form of an embedded photonic quasicrystal, a photonic structure comprising an amorphous array of subregions, or a zone plate structure. The invention provides the benefit of improved light extraction from the LED without undesirable far field illumination patterns.

Abstract: According to one aspect of the present invention, a light emitting diode (LED) structure including an active core layer and at least one substrate layer having a first refractive index, comprises a 2-dimensional photonic quasicrystal in the structure, the photonic quasicrystal comprising an array of regions having a second refractive index, the array exhibiting long range order but short range disorder. The long range order is associated with diffractive properties of the structure and gives rise to uniform-far field diffraction patterns from the LED. The present invention enjoys the benefit of improved light extraction from LEDs without undesirable far field illumination patterns.