Abstract: A light emitting device including a nucleation layer containing aluminum is disclosed. The thickness and aluminum composition of the nucleation layer are selected to match the index of refraction of the substrate and device layers, such that 90% of light from the device layers incident on the nucleation layer is extracted into the substrate. In some embodiments, the nucleation layer is AlGaN with a thickness between about 1000 and about 1200 angstroms and an aluminum composition between about 2% and about 8%. In some embodiments, the nucleation layer is formed over a surface of a wurtzite substrate that is miscut from the c-plane of the substrate. In some embodiments, the nucleation layer is formed at high temperature, for example between 900° and 1200° C. In some embodiments, the nucleation layer is doped with Si to a concentration between about 3e18 cm−3 and about 5e19 cm−3.

Abstract: A light emitting device includes a light source that emits first light in response to an electrical signal, and a fluorescent layer positioned over the light source. The fluorescent layer includes a first fluorescent material which radiates second light and a second fluorescent material which radiates third light. In one embodiment, the second fluorescent material contains europium activated calcium sulfide. In another embodiment, the second fluorescent material contains europium activated nitrido-silicate. In some embodiments, the device includes a light propagation medium which transmits the first, second, and third light as composite output.

Abstract: A lens comprises a bottom surface, a reflecting surface, a first refracting surface obliquely angled with respect to a central axis of the lens, and a second refracting surface extending as a smooth curve from the bottom surface to the first refracting surface. Light entering the lens through the bottom surface and directly incident on the reflecting surface is reflected from the reflecting surface to the first refracting surface and refracted by the first refracting surface to exit the lens in a direction substantially perpendicular to the central axis of the lens. Light entering the lens through the bottom surface and directly incident on the second refracting surface is refracted by the second refracting surface to exit the lens in a direction substantially perpendicular to the central axis of the lens. The lens may be advantageously employed with LEDs, for example, to provide side-emitting light-emitting devices. A lens cap attachable to a lens is also provided.

Abstract: A backlight system comprises a light-emitting panel (1) having a front wall (2) and, opposite thereto, a rear wall (3), and opposite first and second light-transmitting edge surfaces (4; 5) associated with a plurality of first and second light sources (6; 7). Light originating from the light sources (6; 7) is diffused in the panel (1). Parts of the surface areas (8; 9) of the rear wall (3) are provided with extraction means (18, 18′, . . . ; 19, 19′, . . . ) for extracting light from the panel (1). First extraction means (18, 18′, . . . ) extract light from, preferably, the first light source (6), and vice versa In operation, said parts of the surface areas (8; 9) project light on a (LCD) display device panel (34) with an associated color filter (35). In the vicinity of the second edge area (5), the concentration of the first extraction means (18, 18′, . . . ) is higher than that of the second extraction means (19, 19′, . . . ), and vice versa.

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: P-type layers of a GaN based light-emitting device are optimized for formation of Ohmic contact with metal. In a first embodiment, a p-type GaN transition layer with a resistivity greater than or equal to about 7 &OHgr;cm is formed between a p-type conductivity layer and a metal contact. In a second embodiment, the p-type transition layer is any III-V semiconductor. In a third embodiment, the p-type transition layer is a superlattice. In a fourth embodiment, a single p-type layer of varying composition and varying concentration of dopant is formed.

Abstract: A method for forming a luminescent layer on a light emitting semiconductor device includes positioning a stencil on a substrate such that a light emitting semiconductor device disposed on the substrate is located within an opening in the stencil, depositing a stenciling composition including luminescent material in the opening, removing the stencil from the substrate, and curing the stenciling composition to a solid state. The resulting light emitting device includes a stack of layers including semiconductor layers comprising an active region and a luminescent material containing layer having a substantially uniform thickness disposed around at least a portion of the stack. A surface of the luminescent material containing layer not adjacent to the stack substantially conforms to a shape of the stack. In one embodiment, the light emitting device emits white light in a uniformly white spatial profile.

Abstract: A light-emitting diode (LED) and a method of making the device utilize a thick multi-layered epitaxial structure that increases the light extraction efficiency of the device. The LED is an aluminum-gallium-indium-nitride (AlGaInN)-based LED. The thick multi-layered epitaxial structure increases the light extraction efficiency of the device by increasing the amount of emitted light that escapes the device through the sides of the thick multi-layered epitaxial structure. The LED includes a substrate, a buffer layer, and the thick multi-layered epitaxial structure. In the preferred embodiment, the substrate is a sapphire substrate having a textured surface. The textured surface of the substrate randomized light impinges the textured surface, so that an increased amount of emitted light may escape the LED as output light. The multi-layered epitaxial structure includes an upper AlGaInN region, an active region, and a lower AlGaInN region.

Abstract: A light-emitting device includes: a semiconductor structure formed on one side of a substrate, the semiconductor structure having a plurality of semiconductor layers and an active region within the layers; and first and second conductive electrodes contacting respectively different semiconductor layers of the structure; the substrate comprising a material having a refractive index n>2.0 and light absorption coefficient &agr;, at the emission wavelength of the active region, of &agr;>3 cm−1. In a preferred embodiment, the substrate material has a refractive index n>2.3, and the light absorption coefficient, &agr;, of the substrate material is &agr;<1 cm−1.

Abstract: A light source is disclosed that includes a light emitting device such as a III-nitride light emitting diode covered with a luminescent material structure, such as a single layer or multiple layers of phosphor. Any variations in the thickness of the luminescent material structure are less than or equal to 10% of the average thickness of the luminescent material structure. In some embodiments, the thickness of the luminescent material structure is less than 10% of a cross-sectional dimension of the light emitting device. In some embodiments, the luminescent material structure is the only luminescent material through which light emitted from the light emitting device passes. In some embodiments, the luminescent material structure is between about 15 and about 100 microns thick. The luminescent material structure is selectively deposited on the light emitting device by, for example, stenciling or electrophoretic deposition.

Abstract: A light-emitting device comprises a substrate, electrical terminals disposed on a top side of the substrate, and a light-emitting semiconductor device disposed above the substrate. The light-emitting semiconductor device has a bottom side oriented to face toward the top side of the substrate. Electrodes are disposed on the bottom side of the light-emitting semiconductor device and electrically connected to the terminals on the substrate. A glass layer is arranged in a path of output light emitted by the light-emitting semiconductor device. The glass layer contains fluorescent material that converts at least a portion of the output light to converted light having a wavelength different from a wavelength of the output light. The fluorescent material may include SrS:Eu2+ that emits red light and (Sr, Ba, Ca)Ga2S4:Eu2+ that emits green light.

Abstract: A smoothing structure containing indium is formed between the substrate and the active region of a III-nitride light emitting device to improve the surface characteristics of the device layers. In some embodiments, the smoothing structure is a single layer, separated from the active region by a spacer layer which typically does not contain indium. The smoothing layer contains a composition of indium lower than the active region, and is typically deposited at a higher temperature than the active region. The spacer layer is typically deposited while reducing the temperature in the reactor from the smoothing layer deposition temperature to the active region deposition temperature. In other embodiments, a graded smoothing region is used to improve the surface characteristics. The smoothing region may have a graded composition, graded dopant concentration, or both.

Abstract: The present invention provides an LED device comprising a phosphor-converting substrate that converts primary light emitted by the LED, which is blue light, into one or more other wavelengths of light, which then combine with unconverted primary light to produce white light. The substrate is a single crystal phosphor having desired luminescent properties. The single crystal phosphor has the necessary lattice structure to promote single crystalline growth of the light-emitting structure of the LED device. Moreover, the thermo-mechanical properties of the substrate are such that the introduction of excessive strain or cracks in the epitaxial films of the LED device is prevented. The characteristics of the substrate, i.e., the dopant concentration and thickness, are capable of being precisely controlled and tested before the LED device is fabricated so that the fraction of primary light that passes through the substrate without being converted is predictable and controllable.

Abstract: III-Nitride light emitting diodes having improved performance are provided. In one embodiment, a light emitting device includes a substrate, a nucleation layer disposed on the substrate, a defect reduction structure disposed above the nucleation layer, and an n-type III-Nitride semiconductor layer disposed above the defect reduction structure. The n-type layer has, for example, a thickness greater than about one micron and a silicon dopant concentration greater than or equal to about 1019 cm−3. In another embodiment, a light emitting device includes a III-Nitride semiconductor active region that includes at least one barrier layer either uniformly doped with an impurity or doped with an impurity having a concentration graded in a direction substantially perpendicular to the active region.

Abstract: In one embodiment of the present invention, a highly reflective dielectric stack is formed on the mesa wall of a flip-chip LED. The layers of the dielectric stack are selected to maximize reflection of light incident at angles ranging from −10 to 30 degrees, relative to the substrate. The dielectric stack is comprised of alternating low refractive index and high refractive index layers. In some embodiments, the LED is a III-nitride device with a p-contact containing silver, the dielectric stack layer adjacent to the mesa wall has a low refractive index compared to GaN, and the low refractive index layers are Al2O3.

Abstract: A housing and mounting system for a strip lighting device, particularly a lighting device of the kind in which multiple light emitting diode (LED) light sources are arranged at spaced intervals within an elongate tubular housing that is translucent and arranged to diffuse, disperse or scatter the light from the LED light sources. The tubular housing has two longitudinally extending keys integrally formed on the exterior of the tube. The interior of the tube has longitudinally extending formations for supporting mounted LED light sources within the tube.

Abstract: A lens mounted to a light emitting diode package internally redirects light within the lens so that a majority of light is emitted from the lens approximately perpendicular to a package axis of the light emitting diode package. In one embodiment, the light emitted by the light emitting diode package is refracted by a sawtooth portion of the lens and reflected by a total internal reflection portion of the lens.

Abstract: A light emitting device in accordance with an embodiment of the present invention includes a diffractive optical element, a first light emitting diode emitting first light having a first range of wavelengths, and a second light emitting diode emitting second light having a second range of wavelengths. The first light is directed onto the diffractive optical element at a first range of angles of incidence, and the second light is directed onto the diffractive optical element at a second range of angles of incidence. The diffractive optical element diffracts at least a portion of the first light and at least a portion of the second light into the same range of angles of diffraction to obtain light having a desired range of wavelengths. A light emitting device in accordance with an embodiment of the present invention can efficiently mix the outputs of two or more light emitting diodes to form a substantially uniform output of, for example, white light.

Abstract: A white-light emitting diode (LED) is provided that emits primary light at a wavelength that is in the range of 485 to 515 nanometers (nm), which corresponds to a bluish-green color. A portion of the primary light is converted into a reddish-colored light that ranges in wavelength from approximately 600 to approximately 620 nm. At least a portion of the converted light combines with the unconverted portion of the primary light to produce white light. A number of phosphor-converting elements are suitable for use with the LED, including a resin admixed with a phosphor powder, epoxies admixed with a phosphor powder, organic luminescent dyes, phosphor-converting thin films and phosphor-converting substrates. Preferably, the phosphor-converting element is a resin admixed with a phosphor powder in such a manner that a portion of the primary light impinging on the resin is converted into the reddish-colored light and a portion of the primary light passes through the resin without being converted.

Abstract: A lens mounted to a light emitting diode package internally redirects light within the lens so that a majority of light is emitted from the lens approximately perpendicular to a package axis of the light emitting diode package. In one embodiment, the light emitted by the light emitting diode package is refracted by a sawtooth portion of the lens and reflected by a total internal reflection portion of the lens.