Abstract: A crucible is provided that is thermally stable at high temperatures and is suitable for use in the growth of large, bulk AlN, AlxGa1-xN or other nitride single crystals. The crucible is comprised of specially treated tantalum. During the initial treatment, the walls of the crucible are carburized, thus achieving a crucible that can be subjected to high temperatures without deformation. Once the carburization of the tantalum is complete, the crucible undergoes further treatment to protect the surfaces that are expected to come into contact with nitride vapors during crystal growth with a layer of TaN. If the crucible is to be used with a graphite furnace, only the inner surfaces of the crucible are converted to TaN, thus keeping TaC surfaces adjacent to the graphite furnace elements. If the crucible is to be used with a non-graphite furnace, both the inner and outer surfaces of the crucible are converted to TaN.

Abstract: A method and apparatus for achieving multicolor displays using an integrated color chip is provided. The integrated color chip contains one or more multicolor generation sites on a single substrate. Each multicolor generation site is comprised of two or more light emitting regions in close proximity to one another, the number of light emitting regions per site dependent upon the number of required colors. The active light generation system for each light emitting region, e.g., an LED, is preferably identical in device structure although size and shape may vary. In order to achieve the desired colors, one or more light conversion layers are applied to individual light emitting regions. Each light emitting region may also include index matching layers, preferably interposed between the outermost surface of the light emitter and the light conversion layer, and protective layers.

Abstract: A low defect (e.g., dislocation and micropipe) density silicon carbide (SiC) is provided as well as an apparatus and method for growing the same. The SiC crystal, grown using sublimation techniques, is preferably divided into two stages of growth. During the first stage of growth, the crystal grows in a normal direction while simultaneously expanding laterally. Although dislocations and other material defects may propagate within the axially grown material, defect propagation and generation in the laterally grown material are substantially reduced, if not altogether eliminated. After the crystal has expanded to the desired diameter, the second stage of growth begins in which lateral growth is suppressed and normal growth is enhanced. A substantially reduced defect density is maintained within the axially grown material that is based on the laterally grown first stage material.

Abstract: A method and apparatus for achieving multicolor displays using an integrated color chip is provided. The integrated color chip contains one or more multicolor generation sites on a single substrate. Each multicolor generation site is comprised of two or more light emitting regions in close proximity to one another, the number of light emitting regions per site dependent upon the number of required colors. The active light generation system for each light emitting region, e.g., an LED, is preferably identical in device structure although size and shape may vary. In order to achieve the desired colors, one or more light conversion layers are applied to individual light emitting regions. Each light emitting region may also include index matching layers, preferably interposed between the outermost surface of the light emitter and the light conversion layer, and protective layers.

Abstract: A method and apparatus for achieving multicolor displays using an integrated color chip is provided. The integrated color chip contains one or more multicolor generation sites on a single substrate. Each multicolor generation site is comprised of two or more light emitting regions in close proximity to one another, the number of light emitting regions per site dependent upon the number of required colors. The active light generation system for each light emitting region, e.g., an LED, is preferably identical in device structure although size and shape may vary. In order to achieve the desired colors, one or more light conversion layers are applied to individual light emitting regions. Each light emitting region may also include index matching layers, preferably interposed between the outermost surface of the light emitter and the light conversion layer, and protective layers.

Abstract: A method and apparatus for axially growing single crystal silicon carbide is provided. Utilizing the system, silicon carbide can be grown with a dislocation density of less than 104 per square centimeter, a micropipe density of less than 10 per square centimeter, and a secondary phase inclusion density of less than 10 per cubic centimeter. As disclosed, a SiC source and a SiC seed crystal of the desired polytype are co-located within a crucible, the growth zone being defined by the substantially parallel surfaces of the source and the seed in combination with the sidewalls of the crucible. Prior to reaching the growth temperature, the crucible is evacuated and sealed, either directly or through the use of a secondary container housing the crucible. The crucible is comprised of tantalum or niobium that has been specially treated.

Abstract: A method and apparatus for axially growing single crystal silicon carbide is provided. Utilizing the system, silicon carbide can be grown with a dislocation density of less than 104 per square centimeter, a micropipe density of less than 10 per square centimeter, and a secondary phase inclusion density of less than 10 per cubic centimeter. As disclosed, a SiC source and a SiC seed crystal of the desired polytype are co-located within a crucible, the growth zone being defined by the substantially parallel surfaces of the source and the seed in combination with the sidewalls of the crucible. Prior to reaching the growth temperature, the crucible is evacuated and sealed, either directly or through the use of a secondary container housing the crucible. The crucible is comprised of tantalum or niobium that has been specially treated.

Abstract: A method and apparatus for axially growing single crystal silicon carbide is provided. Utilizing the system, silicon carbide can be grown with a dislocation density of less than 104 per square centimeter, a micropipe density of less than 10 per square centimeter, and a secondary phase inclusion density of less than 10 per cubic centimeter. As disclosed, a SiC source and a SiC seed crystal of the desired polytype are co-located within a crucible, the growth zone being defined by the substantially parallel surfaces of the source and the seed in combination with the sidewalls of the crucible. Prior to reaching the growth temperature, the crucible is evacuated and sealed, either directly or through the use of a secondary container housing the crucible. The crucible is comprised of tantalum or niobium that has been specially treated.

Abstract: A rectifier structure that exhibits a low turn-on voltage and allows rapid switching without ringing is provided. The structure utilizes a thin epitaxial layer interposed between the two layers comprising the rectifier junction. Preferably the epitaxial layer is of the same conductivity as the underlying layer while being comprised of the same material as the outermost layer.

Abstract: A method and apparatus for axially growing single crystal silicon carbide is provided. Utilizing the system, silicon carbide can be grown with a dislocation density of less than 104 per square centimeter, a micropipe density of less than 10 per square centimeter, and a secondary phase inclusion density of less than 10 per cubic centimeter. As disclosed, a SiC source and a SiC seed crystal of the desired polytype are co-located within a crucible, the growth zone being defined by the substantially parallel surfaces of the source and the seed in combination with the sidewalls of the crucible. Prior to reaching the growth temperature, the crucible is evacuated and sealed, either directly or through the use of a secondary container housing the crucible. The crucible is comprised of tantalum or niobium that has been specially treated.

Abstract: A low defect (e.g., dislocation and micropipe) density silicon carbide (SiC) is provided as well as an apparatus and method for growing the same. The SiC crystal, grown using sublimation techniques, is preferably divided into two stages of growth. During the first stage of growth, the crystal grows in a normal direction while simultaneously expanding laterally. Although dislocations and other material defects may propagate within the axially grown material, defect propagation and generation in the laterally grown material are substantially reduced, if not altogether eliminated. After the crystal has expanded to the desired diameter, the second stage of growth begins in which lateral growth is suppressed and normal growth is enhanced. A substantially reduced defect density is maintained within the axially grown material that is based on the laterally grown first stage material.

Abstract: A low defect (e.g., dislocation and micropipe) density silicon carbide (SiC) is provided as well as an apparatus and method for growing the same. The SiC crystal, grown using sublimation techniques, is preferably divided into two stages of growth. During the first stage of growth, the crystal grows in a normal direction while simultaneously expanding laterally. Although dislocations and other material defects may propagate within the axially grown material, defect propagation and generation in the laterally grown material are substantially reduced, if not altogether eliminated. After the crystal has expanded to the desired diameter, the second stage of growth begins in which lateral growth is suppressed and normal growth is enhanced. A substantially reduced defect density is maintained within the axially grown material that is based on the laterally grown first stage material.

Abstract: A method and an apparatus for growing monocrystalline aluminum nitride are provided, the method and apparatus allowing high single crystal growth rates to be achieved. In one aspect, the seed crystal and the aluminum source are placed in a growth chamber such that the growth surface of the seed crystal is substantially parallel to the evaporating surface of the aluminum surface. In another aspect, the inner surfaces of the growth chamber are comprised of an alloy of tantalum and carbon. In another aspect, during crystal growth the aluminum source is kept at a temperature higher than the seed crystal in order to maintain an axial temperature gradient within the growth chamber. In another aspect, during crystal growth the nitrogen pressure within the growth chamber is at least equal to the pressure exerted by the aluminum-nitrogen vapor mixture.

Abstract: A rectifier structure that exhibits a low turn-on voltage and allows rapid switching without ringing is provided. The structure utilizes a thin epitaxial layer interposed between the two layers comprising the rectifier junction. Preferably the epitaxial layer is of the same conductivity as the underlying layer while being comprised of the same material as the outermost layer.

Abstract: A low defect (e.g., dislocation and micropipe) density silicon carbide (SiC) is provided as well as an apparatus and method for growing the same. The SiC crystal, growing using sublimation techniques, is preferably divided into two stages of growth. During the first stage of growth, the crystal grows in a normal direction while simultaneously expanding laterally. Although dislocation and other material defects may propagate within the axially grown material, defect propagation and generation in the laterally grown material are substantially reduced, if not altogether eliminated. After the crystal has expanded to the desired diameter, the second stage of growth begins in which lateral growth is suppressed and normal growth is enhanced. A substantially reduced defect density is maintained within the axially grown material that is based on the laterally grown first stage material.