CN202564429U - Light emitting diode (LED) with back plating structure - Google Patents
Light emitting diode (LED) with back plating structure Download PDFInfo
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- CN202564429U CN202564429U CN2012202110657U CN201220211065U CN202564429U CN 202564429 U CN202564429 U CN 202564429U CN 2012202110657 U CN2012202110657 U CN 2012202110657U CN 201220211065 U CN201220211065 U CN 201220211065U CN 202564429 U CN202564429 U CN 202564429U
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Abstract
The utility model discloses a light emitting diode (LED) with a back plating structure. The LED with the back plating structure comprises an electrode p, an electrode n and a substrate with a non light-out surface and a light-out surface. An n-type gallium nitride (GaN) layer, a quantum well, a p-type GaN layer, an indium tin oxide layer and a passivation layer are arranged in sequence on the light-out surface of the substrate. The electrode p is located on the upper surface of the indium tin oxide layer, and the electrode n is arranged on the upper surface of an n-type GaN layer 7. A Bragg reflecting layer is arranged on the non light-out surface of the substrate and formed by aluminium oxide layers and titanium dioxide layers in an alternately arrayed mode, and the adjacent aluminium oxide layers and titanium dioxide layers are mutually coated in an attaching mode; and the refractive index of the aluminium oxide layers is smaller than that of the titanium dioxide layers. The LED with the back plating structure can improve the light extraction efficiency of the LED.
Description
Technical field
The utility model belongs to the semiconductor lighting device, specifically, relates to a kind of light-emitting diode with back of the body plating structure.
Background technology
In recent years; Basic LED (the light-emitting diode of gallium nitride (chemical formula is GaN); English full name " Light Emitting Diode " is called for short " LED ") development is swift and violent. and with LED is the semiconductor illuminating light source of core, will replace incandescent lamp, fluorescent lamp future and becomes lighting source of new generation.Gallium nitride based LED construction is as shown in Figure 1, comprises p electrode, SQW, passivation layer, indium tin oxide layer, p type GaN layer, n electrode, n type GaN layer and substrate.Therefore yet still there are problems such as luminous efficiency is low, cost is high, poor reliability at present in LED, and the luminous efficiency of commercial white light LEDs is also lower, has limited its march toward speed of illumination and other application.
LED is as a kind of light source, and an important indicator weighing it is exactly photoelectric conversion efficiency or luminous efficiency.Two basics point of departure that improve the LED luminous efficiency improve its internal quantum efficiency and external quantum efficiency exactly.The external quantum efficiency η of LED
Ex=η
InC
Ex, in the formula, η
InIt is internal quantum efficiency; C
ExIt is light extraction efficiency.Because the light extraction efficiency of GaN base LED is very low, and internal quantum efficiency can reach very high level, becomes the key that improves LED external quantum efficiency that is luminous efficiency so improve the light extraction efficiency of LED.For traditional Sapphire Substrate GaN base LED; It is many-sided causing the low-down reason of light extraction efficiency; Comprise lattice defect to the absorption of light, substrate to absorption, inside (repetition) of light absorb, the light of the stopping of electrode, particularly LED emission is in the outgoing process; Owing to the reasons such as light loss that cause with the total reflection between the glue in chip and encapsulation, so that only have 4% the light can be from the surperficial outgoing of LED, most light then be limited in LED inside; Finally become thermal losses, thereby cause extremely low light extraction efficiency.Therefore, the light extraction efficiency that how to improve LED is one of research topic that needs to be resolved hurrily most in the field of semiconductor illumination.
Summary of the invention
Technical problem:The utility model technical problem to be solved is: a kind of light-emitting diode with back of the body plating structure is provided, improves the light extraction efficiency of LED.
Technical scheme:For solving the problems of the technologies described above, the technical scheme that the utility model adopts is:
A kind of light-emitting diode with back of the body plating structure; Comprise p electrode, n electrode and have the substrate of non-exiting surface and exiting surface; On the exiting surface of substrate, be sequentially with n type GaN layer, SQW, p type GaN layer and indium tin oxide layer and passivation layer; The p electrode is positioned at the upper surface of indium tin oxide layer, and the n electrode is positioned at the upper surface of n type GaN layer, and the non-exiting surface of described substrate is provided with Bragg reflecting layer; This Bragg reflecting layer is alternately rearranged by alundum (Al layer and titanium dioxide layer, and pastes each other between adjacent alundum (Al layer and the titanium dioxide layer; The refractive index of alundum (Al layer is less than the refractive index of titanium dioxide layer.
Described light-emitting diode with back of the body plating structure also comprises metallic reflector, and this metallic reflector is positioned at the outer surface of Bragg reflecting layer.
Beneficial effect:Compared with prior art, the utlity model has following beneficial effect:
1.LED light extraction efficiency high.In the prior art, only have 4% the light can be from LED surface outgoing, most light then be limited in LED inside, finally becomes thermal losses.And in the technical scheme of the utility model; The non-exiting surface of light-emitting diode substrate is provided with Bragg reflecting layer; Can the light of directive chip bottom be utilized Bragg reflection principle reflected back upper surface; The reflectivity of Bragg reflecting layer can reach more than 90%, thereby improves the LED external quantum efficiency, and then improves the light extraction efficiency height of LED.
2. have good thermal conductivity, help the heat radiation of led chip.In the technical scheme of the utility model, one metallic reflector can be set at the outer surface of Bragg reflecting layer.Metallic reflector can further improve reflectivity.In addition, metallic reflector has good thermal conductivity, helps the heat radiation of led chip.Especially for great power LED, metallic reflector has important value to the thermal diffusivity that improves LED.
Description of drawings
Fig. 1 is the gallium nitride based LED construction sketch map of Sapphire Substrate in the prior art.
Fig. 2 is the structural representation of the utility model.
Fig. 3 is a kind of improvement structural representation of the utility model.
Fig. 4 is the structural representation of the Bragg reflecting layer of Fig. 2, and two arrow lines that are positioned at the top are represented incident ray and reflection ray.
Fig. 5 is the Bragg reflecting layer of Fig. 3 and the structural representation of metal level, and two arrow lines that are positioned at the top are represented incident ray and reflection ray.
Have among the figure: p electrode 1, SQW 2, passivation layer 3, ITO4, p type GaN layer 5, n electrode 6, n type GaN layer 7, substrate 8, Bragg reflecting layer 9, alundum (Al layer 91, titanium dioxide layer 92, metallic reflector 10.
Embodiment
Below in conjunction with accompanying drawing, the technical scheme of the utility model is elaborated.
As shown in Figure 2; A kind of light-emitting diode of the utility model with back of the body plating structure; Comprise p electrode 1, n electrode 6 and have the substrate 8 of non-exiting surface and exiting surface; On the exiting surface of substrate 8, be sequentially with n type GaN layer 7, SQW 2, p type GaN layer (GaN is the chemical formula of gallium nitride) 5 and indium tin oxide layer 4 and passivation layer 3, p electrode 1 is positioned at the upper surface of indium tin oxide layer 4, and n electrode 6 is positioned at the upper surface of n type GaN layer 7.The non-exiting surface of substrate 8 is provided with Bragg reflecting layer 9.Substrate 8 adopts sapphire, GaAs, carborundum or silicon materials to process.Bragg reflecting layer 9 is alternately rearranged by alundum (Al layer 91 and titanium dioxide layer 92, and pastes each other between adjacent alundum (Al layer 91 and the titanium dioxide layer 92.The refractive index of alundum (Al layer 91 is less than the refractive index of titanium dioxide layer 92.That is to say; As shown in Figure 4, first alundum (Al layer 91 is covered on the non-exiting surface of substrate 8, first titanium dioxide layer 92 is covered on the outer surface of first alundum (Al layer 91 again; Then second alundum (Al layer 91 is covered on the outer surface of first titanium dioxide layer 92; Then second titanium dioxide layer 92 is covered on the outer surface of second alundum (Al layer 91 ..., circulate with this.Certainly; It also can be the non-exiting surface that earlier first titanium dioxide layer 92 is covered on substrate 8; Again first alundum (Al layer 91 is covered on the outer surface of first titanium dioxide layer 92, then second titanium dioxide layer 92 is covered on the outer surface of first alundum (Al layer 91, then second alundum (Al layer 91 is covered on second titanium dioxide layer 92 outer surface;, circulate with this.Alundum (Al layer 91 in the Bragg reflecting layer 9 is identical with the number of plies of titanium dioxide layer 92, and alundum (Al layer 91 respectively is 1 layer-20 layers with titanium dioxide layer 92.That is to say that alundum (Al layer 91 is alternately arranged 1 time-20 times with titanium dioxide layer 92, for example can be 1 time, 5 times, 8 times, 10 times, 15 times, 18 times or 20 times.The optical thickness of the optical thickness of alundum (Al layer 91 and titanium dioxide layer 92 is respectively 1/4 of reverberation wavelength.Also promptly, the optical thickness of alundum (Al layer 91 is 1/4 refractive indexes divided by alundum (Al layer 91 of lambda1-wavelength, and the optical thickness of titanium dioxide layer 92 is 1/4 refractive indexes divided by titanium dioxide layer 92 of lambda1-wavelength.
Further, like Fig. 3 and shown in Figure 5, described light-emitting diode with back of the body plating structure also comprises metallic reflector 10, and this metallic reflector 10 is positioned at the outer surface of Bragg reflecting layer 9.Outer surface at Bragg reflecting layer 9 is provided with a metallic reflector 10.Bragg reflecting layer 9 can both improve reflectivity with metallic reflector 10, and the thermal conductivity of metallic reflector 10 is good, so have good thermal conductivity.The combination of Bragg reflecting layer 9 and metallic reflector 10 has high reflectance and good thermal conductivity to the corresponding wave band of LED emergent light, and the heat dissipation characteristics that improves great power LED is had important value.The thickness of described metallic reflector 10 is between 50 nm-300 nm.This metallic reflector 10 is made of aluminum.Certainly, can also select other metal materials, for example silver.But when being to use silver-colored material, then needing on silver, plate the sulfuration that layer of metal nickel prevents silver again, or take other anti-sulfuration measure.
The utility model increases on the non-exiting surface of the substrate 8 of existing light-emitting diode Bragg reflecting layer 9 is set, and Bragg reflecting layer 9 is formed by alundum ( Al layer 91 and 92 two kinds of material alternate combinations of titanium dioxide layer.Bragg reflecting layer 9 can be with the light that is originally absorbed by chip bottom reflected back LED again, thereby can significantly improve the light extraction efficiency of LED.
Only two surperficial outgoing up and down that the active area of LED sends, and packaged LED is that " unidirectional " is luminous, therefore is necessary light reflection or directly outgoing with the directive chip bottom.In the light-emitting diode of the utility model, after incident light was injected, Bragg reflecting layer 9 can utilize the light of directive chip bottom Bragg reflection principle reflected back upper surface, thereby improved the LED external quantum efficiency.The optical thickness of the alundum (Al layer 91 in the Bragg reflecting layer 9 and the optical thickness of titanium dioxide layer 92 are respectively 1/4 of reverberation wavelength.Bragg reflecting layer 9 is a kind of quarter-wave sandwich constructions, is equivalent to simple 1-D photon crystal.Because the electromagnetic wave that frequency drops in the energy gap scope can't penetrate, the reflectivity of Bragg mirror can reach more than 90%.The energy gap position can be adjusted through the refractive index or the thickness that change alundum (Al layer 91 or titanium dioxide layer 92.
Gallium nitride based LED construction with Sapphire Substrate is an example, specifies the high advantage of the light extraction efficiency that light-emitting diode had of the utility model.
As shown in Figure 2, light-emitting diode comprises p electrode 1, SQW 2, passivation layer 3, indium tin oxide layer 4, p type GaN layer 5, n electrode 6, n type GaN layer 7, substrate 8, Bragg reflecting layer 9 and metallic reflector 10.Growing n-type GaN layer 7 on the exiting surface of substrate 8; The upper surface grown quantum trap 2 and the n electrode 6 of n type GaN layer 7; The upper surface growing p-type GaN layer 5 of SQW 2, the upper surface growth indium tin oxide layer 4 of p type GaN layer 5, the upper surface growth p electrode 1 and the passivation layer 3 of indium tin oxide layer 4.Growth Bragg reflecting layer 9 on the non-exiting surface of substrate 8, the outer surface growing metal reflector 10 of Bragg reflecting layer 9.Bragg reflecting layer 9 is alternately to be arranged with titanium dioxide layer 92 by alundum (Al layer 91 to form.
Employing is the blue-light LED chip of 450 nm with peak wavelength, and the optical thickness of titanium dioxide layer 92 is 44 nm, and the optical thickness of alundum (Al layer 91 is 66 nm, and titanium dioxide layer 92 is provided with 6 layers respectively with alundum (Al layer 91.During incident light vertical incidence LED, can obtain the reflectivity more than 95%.
LED as shown in Figure 3, its structure is identical with LED structure shown in Figure 2, and different is to be provided with layer of metal reflector 10 at Bragg reflecting layer 9 outer surfaces.
Employing is the blue-light LED chip of 450 nm with peak wavelength, and the optical thickness of titanium dioxide layer 92 is 44 nm, and the optical thickness of alundum (Al layer 91 is 66 nm, and titanium dioxide layer 92 is provided with 3 layers respectively with alundum (Al layer 91.Metallic reflector 10 adopts aluminum to process, and the thickness of metallic reflector 10 is 100 nm.During incident light vertical incidence LED, can obtain the reflectivity more than 98%.
Above-described specific embodiment has carried out further detailed explanation to purpose, technical scheme and the beneficial effect of the utility model.But should be emphasized that the above embodiment is merely the preferred embodiments of the utility model, is not the protection range that is used to limit the utility model.All within the spirit and principle of the utility model, any modification that the back of the body of the utility model plating structure is made, replacement, improvement etc. all should be included in the protection range of the utility model.
Claims (7)
1. one kind has the light-emitting diode that the back of the body plates structure; Comprise p electrode (1), n electrode (6) and have the substrate (8) of non-exiting surface and exiting surface; On the exiting surface of substrate (8), be sequentially with n type GaN layer (7), SQW (2), p type GaN layer (5) and indium tin oxide layer (4) and passivation layer (3); P electrode (1) is positioned at the upper surface of indium tin oxide layer (4); N electrode (6) is positioned at the upper surface of n type GaN layer (7), it is characterized in that, the non-exiting surface of described substrate (8) is provided with Bragg reflecting layer (9); This Bragg reflecting layer (9) is alternately rearranged by alundum (Al layer (91) and titanium dioxide layer (92), and pastes each other between adjacent alundum (Al (91) layer and the titanium dioxide layer (92); The refractive index of alundum (Al layer (91) is less than the refractive index of titanium dioxide layer (92).
2. according to the described light-emitting diode of claim 1, it is characterized in that also comprise metallic reflector (10), this metallic reflector (10) is positioned at the outer surface of Bragg reflecting layer (9) with back of the body plating structure.
3. according to the described light-emitting diode of claim 2, it is characterized in that the thickness of described metallic reflector (10) is between 50 nm-300 nm with back of the body plating structure.
4. according to the described light-emitting diode of claim 3, it is characterized in that described metallic reflector (10) is made of aluminum with back of the body plating structure.
5. according to any one described light-emitting diode in the claim 1 to 4, it is characterized in that the optical thickness of the optical thickness of described alundum (Al layer (91) and titanium dioxide layer (92) is respectively 1/4 of reverberation wavelength with back of the body plating structure.
6. according to the described light-emitting diode of claim 5 with back of the body plating structure; It is characterized in that; Alundum (Al layer (91) in the described Bragg reflecting layer (9) is identical with the number of plies of titanium dioxide layer (92), and alundum (Al layer (91) and titanium dioxide layer (92) respectively are 1 layer-20 layers.
7. according to the described light-emitting diode of claim 1, it is characterized in that described substrate (8) adopts sapphire, GaAs, carborundum or silicon materials to process with back of the body plating structure.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2012202110657U CN202564429U (en) | 2012-05-11 | 2012-05-11 | Light emitting diode (LED) with back plating structure |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2012202110657U CN202564429U (en) | 2012-05-11 | 2012-05-11 | Light emitting diode (LED) with back plating structure |
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| CN202564429U true CN202564429U (en) | 2012-11-28 |
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| CN2012202110657U Expired - Fee Related CN202564429U (en) | 2012-05-11 | 2012-05-11 | Light emitting diode (LED) with back plating structure |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102646772A (en) * | 2012-05-11 | 2012-08-22 | 东南大学 | Light-emitting diode (LED) with back plating structure |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102646772A (en) * | 2012-05-11 | 2012-08-22 | 东南大学 | Light-emitting diode (LED) with back plating structure |
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| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| CF01 | Termination of patent right due to non-payment of annual fee | ||
| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20121128 Termination date: 20170511 |