Abstract: A method of forming a light emitting device includes providing a sapphire substrate, growing an Al1?xGaxN first layer by vapor deposition on the substrate at a temperature between about 1000° C. and about 1180° C., and growing a III-nitride second layer overlying the first layer. The first layer may have a thickness between about 500 angstroms and about 5000 angstroms. In some embodiments, reaction between the group V precursor and the substrate is reduced by starting with a low molar ratio of group V precursor to group III precursor, then increasing the ratio during growth of the first layer, or by using nitrogen as an ambient gas.

Abstract: A light emitting device includes a region of first conductivity type, a region of second conductivity type, an active region, and an electrode. The active region is disposed between the region of first conductivity type and the region of second conductivity type and the region of second conductivity type is disposed between the active region and the electrode. The active region has a total thickness less than or equal to about 0.25?n and has a portion located between about 0.6?n and 0.75?n from the electrode, where ?n is the wavelength of light emitted by the active region in the region of second conductivity type. In some embodiments, the active region includes a plurality of clusters, with a portion of a first cluster located between about 0.6?n and 0.75?n from the electrode and a portion of a second cluster located between about 1.2?n and 1.35?n from the electrode.

Abstract: An LED lamp includes an exterior shell that has the same form factor as a conventional incandescent light bulb, such as a PAR type bulb. The LED lamp includes an optical reflector that is disposed within the shell and that directs the light emitted from one or more LEDs. The optical reflector and shell define a space that is used to channel air to cool the device. The LED is mounted on a heat sink that is disposed within the shell. A fan moves air over the heat sink and through the spaced defined by the optical reflector and the shell. The shell includes one or more apertures that serve as air inlet or exhaust apertures. One or more apertures defined by the optical reflector and shell at the opening of the shell can also be used as air exhaust or inlet apertures.

Abstract: A dielectric layer is formed on the mesa wall of a flip-chip LED. The dielectric layer is selected to maximize reflection of light incident at angles ranging from 10 degrees towards the substrate to 30 degrees away from the substrate. In some embodiments, the LED is a III-nitride device with a p-contact containing silver, the dielectric layer adjacent to the mesa wall is a material with a low refractive index compared to GaN, such as Al2O3.

Abstract: A light emitting device includes several LEDs, mounted on a shared submount, and coupled to circuitry formed on the submount. The LEDs can be of the III-Nitride type. The architecture of the LEDs can be either inverted, or non-inverted. Inverted LEDs offer improved light generation. The LEDs may emit light of the same wavelength or different wavelengths. The circuitry can couple the LEDs in a combination of series and parallel, and can be switchable between various configurations. Other circuitry can include photosensitive devices for feedback and control of the intensity of the emitted light, or an oscillator, strobing the LEDs.

Abstract: A light emitting device and a method of making the same are provided. The light emitting device includes a light emitting diode and a submount. A phosphormaterial is disposed around at least a portion of the light emitting diode. An underfill is disposed between a first surface of the light emitting diode and a first surface of the submount. The underfill reduces contamination of the light emitting diode by the phosphor material.

Abstract: A device includes a submount, and a semiconductor light emitting device mounted on first and second conductive regions on a first side of the submount in a flip chip architecture configuration. The submount has third and fourth conductive regions on a second side of the submount. The third and fourth conductive regions may be used to solder the submount to structure such as a board, without the use of wire bonds. The first and third conductive regions are electrically connected by a first conductive layer and the second and fourth conductive regions are electrically connected by a second conductive layer. The first and second conductive layers may be disposed on the outside of the submount or within the submount.

Abstract: Light-emitting devices are disclosed that comprise a light source emitting first light, a first material substantially transparent to and located to receive at least a portion of the first light, and particles of a second material dispersed in the first material. The second material has an index of refraction greater than an index of refraction of the first material at a wavelength of the first light. The particles of the second material have diameters less than about this wavelength. Particles of a third material may also be dispersed in the first material.

Abstract: A method for fabricating a light-emitting semiconductor device including a III-Nitride quantum well layer includes selecting a facet orientation of the quantum well layer to control a field strength of a piezoelectric field and/or a field strength of a spontaneous electric field in the quantum well layer, and growing the quantum well layer with the selected facet orientation. The facet orientation may be selected to reduce the magnitude of a piezoelectric field and/or the magnitude of a spontaneous electric field, for example. The facet orientation may also be selected to control or reduce the magnitude of the combined piezoelectric and spontaneous electric field strength.

Abstract: A low defect gallium nitride based semiconductor, and method for its production, is disclosed. A first gallium nitride based semiconductor layer overlying a substrate of a dissimilar material is grown. A trench is formed in the first gallium nitride based semiconductor layer. A material is deposited on a surface of the first gallium nitride based semiconductor layer to prevent a second gallium nitride based semiconductor layer, of a material different from the first gallium nitride based semiconductor layer, from nucleating thereon. The bottom surface of the trench is of a material such that the second gallium nitride based semiconductor layer will not nucleate thereon. The second gallium nitride based semiconductor material is grown, extending from at least one of the side walls of the trench, the second gallium nitride based semiconductor material having fewer defects than the first gallium nitride based semiconductor layer.

Abstract: A III-nitride device includes a first n-type layer, a first p-type layer, and an active region separating the first p-type layer and the first n-type layer. The device may include a second n-type layer and a tunnel junction separating the first and second n-type layers. First and second contacts are electrically connected to the first and second n-type layers. The first and second contacts are formed from the same material, a material with a reflectivity to light emitted by the active region greater than 75%. The device may include a textured layer disposed between the second n-type layer and the second contact or formed on a surface of a growth substrate opposite the device layers.

Abstract: A color, transmissive LCD uses a backlight that supplies a uniform blue light to the back of the liquid crystal layer in an LCD. The blue light, after being modulated by the liquid crystal layer, is then incident on the back surface of phosphor material located above the liquid crystal layer. A first phosphor material, when irradiated with the blue light, generates red light for the red pixel areas of the display, and a second phosphor material, when irradiated with the blue light, generates green light for the green pixel areas of the display. No phosphor is deposited over the blue pixel areas.

Abstract: The present invention is an inverted III-nitride light-emitting device (LED) with enhanced total light generating capability. A large area device has an n-electrode that interposes the p-electrode metallization to provide low series resistance. The p-electrode metallization is opaque, highly reflective, and provides excellent current spreading. The p-electrode at the peak emission wavelength of the LED active region absorbs less than 25% of incident light per pass. A submount may be used to provide electrical and thermal connection between the LED die and the package. The submount material may be Si to provide electronic functionality such as voltage-compliance limiting operation. The entire device, including the LED-submount interface, is designed for low thermal resistance to allow for high current density operation. Finally, the device may include a high-refractive-index (n>1.8) superstrate.

Abstract: A III-nitride light emitting device includes an n-type layer, a p-type layer, and an active region capable of emitting light between the p-type layer and the n-type layer. The active region includes at least one additional p-type layer. The p-type layer in the active region may be a quantum well layer or a barrier layer. In some embodiments, both the quantum well layers and the barrier layers in the active region are p-type. In some embodiments, the p-type layer in the active region has an average dislocation density less than about 5×108 cm−2.

Abstract: An LED driver circuit and method are disclosed where a plurality of arrays of light emitting diodes each have a transistor connected to each respective array of light emitting diodes. A PWM controller has an input for receiving a voltage reference and an output connected to selected transistors for driving the selected transistors and setting a PWM duty cycle for the selected arrays of light emitting diodes to determine the brightness of selected light emitting diodes. An oscillator is connected to the PWM controller for driving the PWM controller.

Abstract: A system includes a radiation source capable of emitting first light and a fluorescent material capable of absorbing the first light and emitting second light having a different wavelength than the first light. The fluorescent material is a phosphor having the formula (Lu1-x-y-a-bYxGdy)3(Al1-zGaz)5O12:CeaPrb wherein 0<x<1, 0<y<1, 0<z≦0.1, 0<a≦0.2 and 0<b≦0.1. In some embodiments, the (Lu1-x-y-a-bYxGdy)3(Al1-zGaz)5O12:CeaPrb is combined with a second fluorescent material capable of emitting third light. The second fluorescent material may be a red-emitting phosphor, such that the combination of first, second, and third light emitted from the system appears white.

Abstract: A III-nitride light emitting device including a substrate, a first conductivity type layer overlying the substrate, a spacer layer overlying the first conductivity type layer, an active region overlying the spacer layer, a cap layer overlying the active region, and a second conductivity type layer overlying the cap layer is disclosed. The active region includes a quantum well layer and a barrier layer containing indium. The barrier layer may be doped with a dopant of first conductivity type and may have an indium composition between 1% and 15%. In some embodiments, the light emitting device includes an InGaN lower confinement layer formed between the first conductivity type layer and the active region. In some embodiments, the light emitting device includes an InGaN upper confinement layer formed between the second conductivity type layer and the active region. In some embodiments, the light emitting device includes an InGaN cap layer formed between the upper confinement layer and the active region.

Abstract: A structure that may be used as a backlight for a liquid crystal display includes a light source and an optical waveguide. The optical waveguide is illuminated by the light source from an edge of the optical waveguide. The optical waveguide has a plurality of adjacent areas for illuminating corresponding parts of a liquid crystal panel. Each of the areas is provided with an independently controllable light source for illuminating the area.

Abstract: In accordance with the invention, a light emitting device includes a substrate, a layer of first conductivity type overlying the substrate, a light emitting layer overlying the layer of first conductivity type, and a layer of second conductivity type overlying the light emitting layer. A plurality of vias are formed in the layer of second conductivity type, down to the layer of first conductivity type. The vias may be formed by, for example, etching, ion implantation, or selective growth of the layer of second conductivity type. A set of first contacts electrically contacts the layer of first conductivity type through the vias. A second contact electrically contacts the layer of second conductivity type. In some embodiments, the area of the second contact is at least 75% of the area of the device. In some embodiments, the vias are between 2 and 100 microns wide and spaced between 5 and 1000 microns apart.

Abstract: A light emitting device includes a first active region, a second active region, and a tunnel junction. The tunnel junction includes a layer of first conductivity type and a layer of second conductivity type, both thinner than a layer of first conductivity type and a layer of second conductivity type surrounding the first active region. The tunnel junction permits vertical stacking of the active regions, which may increase the light generated by a device without increasing the size of the source.