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Light emitting device

A technology of light-emitting devices and light-emitting units, which is applied to laser parts, lasers, semiconductor devices, etc., can solve the problems of reducing the light-emitting surface and limiting the light-emitting surface.

Inactive Publication Date: 2004-02-04
MATSUSHITA ELECTRIC WORKS LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, due to the structure in which the outer semiconducting layer is covered by electrodes, the light-emitting surface must be reduced accordingly, thus limiting the light-emitting surface
Furthermore, although a crystalline substrate may have a wider radiating surface than an outer semiconductor layer covered with electrodes, a crystalline substrate on which a semiconductor layer is formed is not used to provide a radiating surface with a rough surface.

Method used

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Examples

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no. 1 example

[0040] The first embodiment Figure 1-7 >

[0041] see figure 1 , which shows a light emitting device according to a first embodiment of the present invention. The light emitting device is used, for example, as a discrete component mounted on a printed circuit board to provide visible light or ultraviolet light by receiving a control voltage. The device consists of sapphire (α-Al 2 o 3) made of a transparent crystal substrate 10 on which a semiconductor light emitting unit 20 as a light source is formed. The cell 20 is composed of a first semiconductor layer 21 composed of n-type GaN (gallium nitride) followed by a second semiconductor layer 22 composed of p-type GaN. The first semiconductor layer 21 is formed on the C-plane of the crystal substrate 10 by epitaxial growth, and the second semiconductor layer 22 is formed on the first semiconductor layer 21 by epitaxial growth, so as to form an interface between the two layers. When a control voltage is...

no. 2 example

[0048] Figure 8A and 8B A light emitting device according to a second embodiment of the invention is shown, which is the same as the first embodiment, except that the refractive layer 40 is realized by an array of recesses 43 . In other words, the second medium is defined by the ambient medium, ie the air trapped in the recess, while the first medium 41 is defined by the non-revised substrate. First, the top surface of the substrate 10 is processed by laser beam irradiation to provide an array of columnar correction media 42, such as Figure 6 As shown in A. Next, the correction medium 42 is removed using a suitable etchant, leaving the recess 43 . For example, an aqueous solution of 5% hydrofluoric acid is used as an etching solution. The resulting depressions 43 are arranged at uniform intervals of 1 / 4 to 4 times the wavelength of light, so that the total refractive index of the refraction layer 40 is between that of the substrate other than the refraction layer and the...

no. 3 example

[0053] The third embodiment Figure 11 &12>

[0054] Figure 11 and 12 shows a light emitting device according to a third embodiment of the present invention, which is the same as that of the first embodiment except that a photonic crystal structure 50 is formed inside the crystal substrate 10 and the semiconductor layers 21 and 22 for reflection from the interface Light is reflected towards the top radiating surface of the substrate with the refractive layer 40 . The photonic crystal substrate 50 includes a plurality of columnar crystal units 51 vertically extending on the circumference of the substrate 10 and the semiconductor layers 21 and 22 . The columnar crystal units are formed by laser modification of the substrate and are arranged at uniform intervals of about half the wavelength of light, thereby providing a distinct crystal substrate for reflecting light that cooperates with adjacent unmodified substrates. As such, light generated at the...

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Abstract

A semiconductor light emitting device gives a large radiation surface with an enhanced light radiating capability. A N-type GaN layer (21) and a P-type GaN layer (22) are stacked to define therebetween an interface where a light is generated upon application of voltage across the interface. A light guide (10) on which the GaN layers are developed is utilized to give a wide radiation surface from which the light is given off. The radiation surface is formed with a refractor layer (40) composed of an array of a first medium (41) and a second medium (42) which have individual refraction indexes different from each other and are arranged alternately across the radiation surface. Thus, the light guide (10) can be best utilized to give a large radiation surface, yet formed with the refractor layer (40) which reduces multiple reflections inside of the light guide (10) for effectively passing or radiating the light transmitted through the light guide (10).

Description

technical field [0001] The invention relates to a light-emitting device, in particular to a semiconductor light-emitting device with enhanced light radiation capability. Background technique [0002] Japanese Patent Publication No. 6-291368 discloses a semiconductor light emitting device designed to efficiently emit light. The device includes a crystalline substrate composed of sapphire on which two semiconductor layers of opposite conductivity types are formed. A pair of electrodes is provided to apply a voltage to the interface between the two semiconductor layers for generating light around the interface. Polishing the exposed or outer one of the two semiconductor layers forms a rough surface with an array of microscopic dimples. By forming a rough surface, multiple reflections within the outer semiconductor layer can be reduced, and light is emitted through the rough surface to a large extent. However, due to the structure in which the outer semiconducting layer is co...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01L33/20H01L33/22
CPCH01L33/22H01L33/20H01L33/025H01L2933/0083
Inventor 田中健一郎久保雅男松嶋朝明寺内亮一
Owner MATSUSHITA ELECTRIC WORKS LTD