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: 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: 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.

Abstract: A method for improving the operating stability of compound semiconductor minority carrier devices and the devices created using this method are described. The method describes intentional introduction of impurities into the layers adjacent to the active region, which impurities act as a barrier to the degradation process, particularly undesired defect formation and propagation. A preferred embodiment of the present invention uses O doping of III-V optoelectronic devices during an epitaxial growth process to improve the operating reliability of the devices.

Abstract: A method of forming a photoresist mask on a light emitting device is disclosed. A portion of the light emitting device is coated with photoresist. A portion of the photoresist is exposed by light impinging on the interface of the light emitting device and the photoresist from inside the light emitting device. The photoresist is developed, removing either the exposed photoresist or the unexposed photoresist. In one embodiment, the photoresist mask may be used to form a phosphor coating. After the photoresist is developed to remove the exposed photoresist, a phosphor layer is deposited overlying the light emitting device. The unexposed portion of photoresist is stripped. In some embodiments, the light exposing the photoresist is produced by electrically biasing the light emitting device, or by shining light into the light emitting device through an aperture or by a focussed laser.

Abstract: A light emitting device includes a semiconductor light emitting device chip having a top surface and a side surface, a wavelength-converting material overlying at least a portion of the top surface and the side surface of the chip, and a filter material overlying the wavelength-converting material. The chip is capable of emitting light of a first wavelength, the wavelength-converting material is capable of absorbing light of the first wavelength and emitting light of a second wavelength, and the filter material is capable of absorbing light of the first wavelength. In other embodiments, a light emitting device includes a filter material capable of reflecting light of a first wavelength and transmitting light of a second wavelength.

Abstract: The amount of usefully captured light in an optical system may be increased by concentrating light in a region where it can be collected by the optical system. A light emitting device may include a substrate and a plurality of semiconductor layers. In some embodiments, a reflective material overlies a portion of the substrate and has an opening through which light exits the device. In some embodiments, reflective material overlies a portion of a surface of the semiconductor layers and has an opening through which light exits the device. In some embodiments, a light emitting device includes a transparent member with a first surface and an exit surface. At least one light emitting diode is disposed on the first surface. The transparent member is shaped such that light emitted from the light emitting diode is directed toward the exit surface.

Abstract: A device includes a semiconductor light emitting device and a wavelength-converting material comprising Sr—SiON:Eu2+. The Sr—SiON:Eu2+ wavelength-converting material absorbs light emitted by the light emitting device and emits light of a longer wavelength. The Sr—SiON:Eu2+ wavelength-converting material may be combined with other wavelength-converting materials to make white light. In some embodiments, the Sr—SiON:Eu2+ wavelength-converting layer is combined with a red-emitting wavelength-converting layer and a blue light emitting device to generate emission in colors, which are not achievable by only mixing primary and secondary wavelengths. In some embodiments, the Sr—SiON:Eu2+ wavelength-converting layer is combined with a red-emitting wavelength-converting layer, a blue-emitting wavelength-converting layer, and a UV light emitting device.

Abstract: A trench MOSFET is formed by creating a trench in a semiconductor substrate, then forming a barrier layer over a portion of the side wall of the trench. A thick insulating layer is deposited in the bottom of the trench. The barrier layer is selected such that the thick insulating layer deposits in the bottom of the trench at a faster rate than the thick insulating layer deposits on the barrier layer. Embodiments of the present invention avoid stress and reliability problems associated with thermal growth of insulating layers, and avoid problems with control of the shape and thickness of the thick insulating layer encountered when a thick insulating layer is deposited, then etched to the proper shape and thickness.

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: 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 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 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 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 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 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: 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: 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.