CN102856457B - Gallium nitride based light emitting diode - Google Patents

Gallium nitride based light emitting diode Download PDF

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Publication number
CN102856457B
CN102856457B CN201210351640.8A CN201210351640A CN102856457B CN 102856457 B CN102856457 B CN 102856457B CN 201210351640 A CN201210351640 A CN 201210351640A CN 102856457 B CN102856457 B CN 102856457B
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layer
emitting diode
light
type gan
light emitting
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CN201210351640.8A
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CN102856457A (en
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虞浩辉
周宇杭
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JIANGSU WINAD LIGHTING TECHNOLOGY Co Ltd
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JIANGSU WINAD LIGHTING TECHNOLOGY Co Ltd
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Abstract

The present invention proposes a kind of gallium nitride based light emitting diode, it is ledge structure, has substrate, and the lower surface of described substrate is formed with metallic reflector; The upper surface of described substrate is formed with successively GaN resilient coating, n-type GaN layer, multiple quantum well light emitting layer (MQW), p-type AlGaN layer, p-type GaN layer, transparent electrode layer, p metal electrode; N metal electrode is formed in described n-type GaN layer; The surface of described GaN resilient coating is roughened process rear formation first surface roughened layer; The upper surface of described light-emitting diode, all sides form second surface roughened layer.Wherein, the upper surface of described p-type GaN layer is formed with the parallel reflector of two rows.

Description

Gallium nitride based light emitting diode
Technical field
The invention belongs to technical field of semiconductors, particularly a kind of gallium nitride based light emitting diode.
Background technology
Semiconductor light-emitting-diode application is increasingly extensive, in illumination, particularly there is the trend replacing incandescent lamp and fluorescent lamp, but also face some technical problems at present, particularly light extraction efficiency is lower, usually, affect the reason that light extraction efficiency mainly contains three aspects: a kind of is because material is to the absorption of light, another kind is light producing total reflection through during different medium.
The raising of light-emitting diode luminous efficiency is pursuing a goal of technology always, and improve the quality of epitaxial material, by transparent substrates bonding, thick current expansion window, these all play good effect to the raising of efficiency.But when light leaves diode inside, in any case it all cannot avoid loss occurs, causing the main cause of loss, is that the semi-conducting material owing to forming LED surface layer has high index of refraction.High optical refractive index can cause light to produce total reflection at this semiconductor material surface, thus the light that LED internal is sent cannot be launched fully.At present, improve the total reflection of light in diode inside by surface texture technology in the industry, thus raising luminous efficiency, but, because prior art usually only carries out roughening treatment to the surface that diode portion is grouped into structure, which results in its roughened surface skewness, therefore cannot effective improving luminous efficiency.
Simultaneously, light-emitting diode send only by its internal structure luminescent layer produce, the light that luminescent layer sends mainly is sent by the front of light-emitting diode, and the light sent from its side must first through the total reflection of LED internal structure, the light path of light is changed could be sent by side.Which results in existing light-emitting diode front bright dipping too much and side bright dipping is not enough, therefore also just cause the uneven of light-emitting diode bright dipping.
Fig. 1 is existing light emitting diode construction.In Fig. 1, substrate 101 is formed successively GaN resilient coating 102, n-type GaN layer 103, multiple quantum well light emitting layer (MQW) 104, p-type AlGaN layer 105, p-type GaN layer 106, transparent electrode layer 107, p metal electrode 112; And n-type GaN layer 103 forms n metal electrode 111.Wherein GaN resilient coating 102 surface is roughened process, to form nano level jagged surface coarsening layer 122.Also be formed with metallic reflector 100 below substrate 101, thus multiple quantum well light emitting layer 104 sends light after the reflection of metallic reflector 100, appears (not shown in figure 1) by the front of light-emitting diode or side, to improve luminous efficiency.
In the light emitting diode construction shown in Fig. 1, because roughened layer is only formed at the inside of light-emitting diode, on the surface of i.e. GaN resilient coating 102, therefore, although the light produced by multiple quantum well light emitting layer 104 is through the reflection of roughened layer 122, can improve the luminous efficiency of side in certain degree, but this roughened layer be in LED internal is also not enough to improve luminous efficiency further.
And, the light-emitting diode of structure shown in Figure 1, what visible multiple quantum well light emitting layer 104 sent wide is manyly appeared by the front of light-emitting diode, namely appeared by the upper surface of transparent electrode layer 107, only have a small amount of light to be appeared by the side of light-emitting diode after the total reflection of transparent electrode layer 107.Therefore, the uniformity of luminance of the light-emitting diode of structure shown in Fig. 1 need to improve.
Summary of the invention
The present invention is directed to the problem of prior art, propose a kind of gallium nitride based light emitting diode with coarse surface and reflector, thus improve luminous efficiency and the uniformity of luminance of light-emitting diode.
The gallium nitride based light emitting diode that the present invention proposes is ledge structure, and it has substrate, and the lower surface of described substrate is formed with metallic reflector; The upper surface of described substrate is formed with successively GaN resilient coating, n-type GaN layer, multiple quantum well light emitting layer (MQW), p-type AlGaN layer, p-type GaN layer, transparent electrode layer, p metal electrode; N metal electrode is formed in described n-type GaN layer; The surface of described GaN resilient coating is roughened process rear formation first surface roughened layer; The upper surface of described light-emitting diode, all sides form second surface roughened layer.
Wherein, the upper surface of described p-type GaN layer is formed with the parallel reflector of two rows.
Wherein, described reflector is the anti-layer of Al/Ag alloying metal, AlAs/AlxGa1-xAs distributed Bragg reflecting layer (DBR) or AlInP/ (AlxGa1-x) yIn1-yP distributed Bragg reflecting layer (DBR).
Wherein, described first surface roughened layer and second surface roughened layer are all nanoscale zigzag roughened layer.
Accompanying drawing explanation
Accompanying drawing 1 is the light emitting diode construction schematic diagram only having part coarse surface in prior art.
The light emitting diode construction schematic diagram with coarse surface and reflector that accompanying drawing 2 proposes for the present invention.
The planar structure schematic diagram that accompanying drawing 3 is light-emitting diode shown in Fig. 2.
Embodiment
Fig. 2 is the light-emitting diode that the present invention proposes, and it has the surface of comprehensive alligatoring, and has reflector, therefore, it is possible to significantly improve luminous efficiency and uniformity of luminance.
See Fig. 2, the structure of light-emitting diode 2 is as described below: form GaN resilient coating 202, n-type GaN layer 203, multiple quantum well light emitting layer (MQW) 204, p-type AlGaN layer 205, p-type GaN layer 206, transparent electrode layer 207, p metal electrode 212 successively on the substrate 201; And n-type GaN layer 203 forms n metal electrode 211.Also be formed with metallic reflector 200 below substrate 201, thus multiple quantum well light emitting layer 204 sends light is appeared (not shown in Fig. 2) by the front of light-emitting diode or side, to improve luminous efficiency after the reflection of metallic reflector 200.
In order to the luminous efficiency of light-emitting diode 2 significantly can be improved, in the light emitting diode construction that the present invention proposes, except carrying out roughening treatment on GaN resilient coating 202 surface, to be formed beyond nano level jagged surface coarsening layer 222, also by the upper surface of light-emitting diode 2, namely the upper surface of transparent electrode layer 207 carries out roughening treatment, meanwhile, also further roughening treatment is carried out equally in all sides of light-emitting diode 2, thus form surface coarsening layer 221 as shown in Figure 2.This roughening treatment can carry out wet etching by being immersed in alkaline solution by light-emitting diode 2, utilizes alkaline solution to carry out corrosion to its surface and has come.Also plasma chambers can being utilized to carry out dry etching to light-emitting diode come, wet etching can also being carried out and then utilize plasma chambers to carry out dry etching having combined by being first immersed in alkaline solution.Combine for wet etching and dry etching and form the technique of surface coarsening layer, the present invention does not limit must dry etching after first wet etching, adopts first dry etching to be equally also fine at wet etching.
After roughening treatment is carried out to the whole outer surface of light-emitting diode 2, the light that multiple quantum well light emitting layer 204 sends is behind each surface arriving light-emitting diode 2, light outside transmission critical angle is due to the repeatedly refraction through surface coarsening layer, finally can enter critical angle interior by each surface transmission out, thus make light-emitting diode 2 send more light, therefore also just improve luminous efficiency.
In order to solve the problem of lumination of light emitting diode lack of uniformity in prior art, the light-emitting diode that the present invention proposes also is provided with reflector further.See Fig. 2, two row reflector 231 and 232 are provided with in p-type GaN layer 206, this reflector 231 and 232 can be Al/Ag alloying metal reflector, also can be AlAs/AlxGa1-xAs or AlInP/ (AlxGa1-x) yIn1-yP distributed Bragg reflecting layer (DBR).This reflector 231 and 232 can be arranged on the upper surface (as shown in Figure 2) of p-type GaN layer 206, also can be arranged on the upper surface (not shown in Fig. 2) of p-type AlGaN layer 205, or the lower surface being arranged on p-type GaN layer 206 or p-type AlGaN layer 205 also can.
See Fig. 2, by arranging reflector 231 and 232, a part for the light sent by multiple quantum well light emitting layer 204 is directly appeared by the front of light-emitting diode 2, and another part is then appeared by the side of light-emitting diode 2 after the reflection in reflector 231 and 232.Owing to there being the existence in reflector 231 and 232, the light that so can arrive light-emitting diode 2 front is just restricted to the part in Fig. 2 between reflector 231 and 232, and the light reflected by reflector 231 and 232 can only appear from the side of light-emitting diode 2, therefore, this design just can improve the uniformity of luminance of light-emitting diode front and side.
Fig. 3 is the floor map of Fig. 2, is namely overlooked by the top of Fig. 2 and the schematic diagram obtained.See Fig. 3, reflector 231 and 232 is two parallel array structures, a part for the light that the multiple quantum well light emitting layer 204 of light-emitting diode 2 sends is appeared by the region 300 in Fig. 3, and another part light appears from the side of light-emitting diode due to the reflection in reflector 232 and 231.
So far, foregoing description specifically understands light emitting diode construction of the present invention, now for existing light-emitting diode, while the structure that the present invention proposes can increase substantially luminous efficiency, the uniformity of luminance of light-emitting diode can also be improved further.The embodiment of description is above only the preferred embodiments of the present invention, and it is not intended to limit the present invention.Those skilled in the art, under the prerequisite not departing from spirit of the present invention, can make any amendment, and protection scope of the present invention are limited to the appended claims to the present invention.

Claims (2)

1. a gallium nitride based light emitting diode, described light-emitting diode is ledge structure, and it is made up of 8 Rotating fields; The light-emitting diode of 8 Rotating fields has substrate (201), and the lower surface of described substrate (201) is directly formed with metallic reflector (200); The upper surface of described substrate (201) is first directly formed with GaN resilient coating (202); GaN resilient coating (202) is directly formed n-type GaN layer (203); N-type GaN layer (203) is upper directly forms multiple quantum well light emitting layer (204); Multiple quantum well light emitting layer (204) is upper directly forms p-type AlGaN layer (205); P-type AlGaN layer (205) is directly formed in p-type GaN layer (206), p-type GaN layer (206) and directly form transparent electrode layer (207); Transparent electrode layer (207) is upper directly forms p metal electrode (212); N metal electrode (211) is formed directly in described n-type GaN layer (203); It is characterized in that:
The surface of described GaN resilient coating (202) is roughened process rear formation first surface nanoscale zigzag roughened layer (222);
The upper surface of described light-emitting diode, all sides form second surface nanoscale zigzag roughened layer (221);
Described gallium nitride based light emitting diode is also formed with the parallel reflector of two rows (232,231); This reflector (232,231) is only arranged in p-type GaN layer (206), and the upper surface of reflector (232,231) and the upper surface flush of p-type GaN layer (206).
2. gallium nitride based light emitting diode as claimed in claim 1, is characterized in that:
Described reflector is the anti-layer of Al/Ag alloying metal, AlAs/AlxGa1-xAs distributed Bragg reflecting layer (DBR) or AlInP/ (AlxGa1-x) yIn1-yP distributed Bragg reflecting layer (DBR).
CN201210351640.8A 2012-09-20 2012-09-20 Gallium nitride based light emitting diode Expired - Fee Related CN102856457B (en)

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CN105185878B (en) * 2015-08-18 2017-08-22 厦门市三安光电科技有限公司 A kind of iii-nitride light emitting devices of Flied emission

Citations (2)

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Publication number Priority date Publication date Assignee Title
CN101075652A (en) * 2006-09-05 2007-11-21 武汉迪源光电科技有限公司 Production of coarsening electrode for high-brightness packed LED chip and vertical LED chip
CN101789477A (en) * 2010-02-24 2010-07-28 中国科学院半导体研究所 Method for preparing all-side-wall saw-tooth coarsened light-emitting diode chip

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AU4355200A (en) * 1999-04-28 2000-11-10 Nova Crystals, Inc. Led having embedded light reflectors to enhance led output efficiency
US8633501B2 (en) * 2008-08-12 2014-01-21 Epistar Corporation Light-emitting device having a patterned surface

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101075652A (en) * 2006-09-05 2007-11-21 武汉迪源光电科技有限公司 Production of coarsening electrode for high-brightness packed LED chip and vertical LED chip
CN101789477A (en) * 2010-02-24 2010-07-28 中国科学院半导体研究所 Method for preparing all-side-wall saw-tooth coarsened light-emitting diode chip

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