An efficient light emitting diode is disclosed wherein the spatial distribution of emitted radiation is highly uniform. In accordance with the present invention, a transparent electrode is used to couple current to the light emitting diode junction in a manner that minimizes the resistance at the interface between the transparent electrode and semiconductor diode material. Specifically, it has been found that the interface resistance is significantly reduced, and device efficiency thus increased, by forming a thin metal-based layer at such interface and/or by annealing the transparent electrode after formation on the device.
An IR LED array and method of fabrication having a GaAs wafer with one surface metallized to form a common LED contact. Epitaxially formed on this wafer is a GaAs/GaAlAs heterostructure with successive layers of Ga.sub.1-x Al.sub.x As-n, GaAs-p, and Ga.sub.1-y Al.sub.y As-p on the other surface, followed by an electrical contact layer of GaAs-p+ and an insulating layer of SiO.sub.2, discrete areas of the contact and insulating layers being removed by etching to form viewing windows for the individual LEDs, and with the area of the contact layer bordering the viewing windows being exposed and metallized to provide individual LED electrical contacts. In a second embodiment, the GaAs-p+ layer is dispensed with and the transparent electrically conducting coating is applied directly on both the insulating layer bordering the Ga.sub.1-y Al.sub.y As viewing windows and over the viewing windows. In a third embodiment, an edge emitting LED variant is provided and in a fourth embodiment, various light barrier designs are proposed for preventing optical crosstalk between the individual LEDs.
A light-emitting diode device having a thin film of silicon nitride or the like is selected so that the intensity of the emitted light can be maintained at a more or less constant level even when the temperature of the light-emitting section rises.
There is disclosed a blue light emitting device having a laminated structure, which comprises a buffer layer made of a first conductivity type GaN-based semiconductor, a first cladding layer made of the first conductivity type GaN-based semiconductor, an active layer made of a substantially intrinsic GaN-based semiconductor, and a second cladding layer made of a second conductivity type GaN-based semiconductor, on a conductive substrate such as a conductive sapphire substrate. The GaN-based semiconductors of the present invention are made of quaternary compound semiconductor layers, and preferably made of In.sub.x A.sub.y Ga.sub.1-x-y N whose mole fraction values x, y satisfy 0.ltoreq.x.ltoreq.1, 0.ltoreq.y.ltoreq.1 and x+y.ltoreq.1. The mole fraction values x, y are selected to obtain desired luminous wavelength and intensity.
An illumination device configured so as to produce a uniform illumination distribution incorporating one or more LEDs fabricated such that the top surface emitting the colored light is not obstructed by an electrode or by contacts connecting the LED to a current source. Such a configuration is accomplished by providing a substantially transparent attachment layer that may include an opaque conductive material, but preferably includes transparent conductive particles that, in combination, attach and electrically connect the LED to an electrode disposed upon a substrate.
A compound semiconductor light emitting element includes a light emitting region formed by a pn-junction between a first compound semiconductor layer of a first conductivity type and a second compound semiconductor layer of a second conductivity type. A first electrode is connected to the first compound semiconductor layer and is isolated from the second compund semiconductor layer. A current spreading layer is formed on the second compound semiconductor layer and a block is formed on the second compound semiconductor layer. A second electrode is formed on the block and is connected to the current spreading layer.