The patent's assignee for patent number 8648376 is
News editors obtained the following quote from the background information supplied by the inventors: "The present invention relates to a light emitting device and a method for manufacturing the same, and more particularly, to a light emitting device capable of achieving an enhancement in emission efficiency and an enhancement in reliability and a method for manufacturing the same.
"Light emitting diodes (LEDs) are well known as a semiconductor light emitting device which converts current to light, to emit light. Since a red LED using GaAsP compound semiconductor was made commercially available in 1962, it has been used, together with a GaP:N-based green LED, as a light source in electronic apparatuses, for image display.
"The wavelength of light emitted from such an LED depends on the semiconductor material used to fabricate the LED. This is because the wavelength of the emitted light depends on the band-gap of the semiconductor material representing energy difference between valence-band electrons and conduction-band electrons.
"Gallium nitride (GaN) compound semiconductor has been highlighted in the field of high-power electronic devices including light emitting diodes (LEDs) because it exhibits a high thermal stability and a wide band-gap of 0.8 to 6.2 eV.
"One of the reasons why GaN compound semiconductor has been highlighted is that it is possible to fabricate semiconductor layers capable of emitting green, blue, and white light, using GaN in combination with other elements, for example, indium (In), aluminum (Al), etc.
"Thus, it is possible to adjust the wavelength of light to be emitted, in accordance with the characteristics of a specific apparatus, using GaN in combination with other appropriate elements. For example, it is possible to fabricate a blue LED useful for optical recording or a white LED capable of replacing a glow lamp.
"By virtue of the above-mentioned advantages of the GaN-based material, techniques associated with GaN-based electro-optic devices have rapidly developed since the GaN-based LEDs became commercially available in 1994.
"The brightness or output of an LED manufactured using the above-mentioned GaN-based material mainly depends on the structure of an active layer, the extraction efficiency associated with external extraction of light, the size of the LED chip, the kind and angle of a mold used to assemble a lamp package, the fluorescent material used, etc."
As a supplement to the background information on this patent, VerticalNews correspondents also obtained the inventors' summary information for this patent: "Accordingly, the present invention is directed to a light emitting device and a method for manufacturing the same that substantially obviate one or more problems due to limitations and disadvantages of the related art.
"An object of the present invention is to provide a light emitting device having a structure capable of achieving an enhancement in extraction efficiency while maintaining desired electrical characteristics when a light extracting structure is introduced into the light emitting device, and exhibiting an optimal extraction efficiency in cooperation with a photonic crystal structure, and a method for manufacturing the light emitting device.
"Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention. The objectives and other advantages of the invention may be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.
"To achieve these objects and other advantages and in accordance with the purpose of the invention, as embodied and broadly described herein, alight emitting device comprises: a semiconductor layer; and a light extracting layer arranged on the semiconductor layer and made of a material having a refractive index equal to or higher than a reflective index of the semiconductor layer.
"In another aspect of the present invention, a light emitting device comprises: a photonic crystal layer including at least two photonic crystal structures arranged in the same plane on a semiconductor layer, the photonic crystal structures having different periodicities.
"In another aspect of the present invention, a light emitting device comprises: a photonic crystal layer including a first photonic crystal having a periodic structure and a second photonic crystal having a random structure, the first and second photonic crystals being arranged in the same plane on a semiconductor layer.
"In another aspect of the present invention, a light emitting device comprises: a reflective electrode; a semiconductor layer arranged on the reflective electrode, the semiconductor layer including a light emitting layer; and a photonic crystal formed on the semiconductor layer, wherein a distance between the reflective electrode and a center of the light emitting layer is 0.65.lamda./n to 0.85.lamda./n, where represents a wavelength of emitted light, and 'n' represents a refractive index of the semiconductor layer.
"In another aspect of the present invention, a light emitting device comprises: a reflective electrode; a semiconductor layer arranged on the reflective electrode, the semiconductor layer including a light emitting layer; and a photonic crystal formed on the semiconductor layer, wherein a distance between the reflective electrode and a center of the light emitting layer is an odd multiple of .lamda./4, where '.lamda.' represents a wavelength of emitted light, and 'n' represents a refractive index of the semiconductor layer.
"In still another aspect of the present invention, a method for manufacturing a light emitting device comprises: growing a plurality of semiconductor layers over a substrate; forming a first electrode on the semiconductor layer; removing the substrate; forming a dielectric layer over the semiconductor layer exposed in accordance with the removal of the substrate; forming a plurality of holes in the dielectric layer; etching a surface of the dielectric layer formed with the holes, to form a plurality of grooves in the semiconductor layer; removing the dielectric layer; and forming a second electrode on a surface of the semiconductor layer exposed in accordance with the removal of the dielectric layer.
"It is to be understood that both the foregoing general description and the following detailed description of the present invention are exemplary and explanatory and are intended to provide further explanation of the invention as claimed."
For additional information on this patent, see: Cho,
Keywords for this news article include: Semiconductor,
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