CN102347408B - GaN-base double-blue-light wavelength luminescent device and preparation method thereof - Google Patents
GaN-base double-blue-light wavelength luminescent device and preparation method thereof Download PDFInfo
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- CN102347408B CN102347408B CN201110328387.XA CN201110328387A CN102347408B CN 102347408 B CN102347408 B CN 102347408B CN 201110328387 A CN201110328387 A CN 201110328387A CN 102347408 B CN102347408 B CN 102347408B
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Abstract
The invention discloses a GaN-base double-blue-light wavelength luminescent device and a preparation method thereof, aiming to solve the problem that the color rendering properties of a white-light LED (Light-emitting Diode) which is packaged by stimulating yellow-light fluorescent powder through a single-blue-light chip are not good. The structure of a GaN-base double-blue-light wavelength LED epitaxial wafer is sequentially composed of following members from a substrate: a GaN buffer layer, a GaN intrinsic layer, an n-GaN layer, an asymmetrical n-AlGaN layer, a high In component quantum well, a low In component quantum well and a p-GaN layer. The structure is characterized by leading the asymmetrical n-AlGaN layer between a mixed multi- quantum-well active layer and the n-GaN layer, removing a p-AlGaN electron barrier layer at the side of the p-GaN layer at the same time, and then packaging the double-blue-light wavelength chip and the yellow-light fluorescent powder to form the white-light LED.
Description
Technical field
The present invention relates to semiconductor photoelectronic device field, specifically, relate to two blue-light wavelength luminescent devices of a kind of GaN base and preparation method thereof.
Background technology
Light-emitting diode is a kind of semiconductor solid-state optical source, it has, and volume is little, low power consuming, low voltage drive, fast response time, life-span length, sound construction, shock resistance and shock resistance strong, be conducive to the many merits such as environmental protection.At aspects such as illumination, demonstration, indications, there is very wide application prospect, so LED will become the new light sources of alternative traditional lighting device of 21 century.
GaN base LED preparation is through the growth of LED epitaxial wafer, and LED chip preparation and LED encapsulate three key links.GaN material growth method has a lot, for example: metal organic chemical vapor deposition (MOCVD), molecular beam epitaxy (MBE), halide vapour phase epitaxy (HVPE) etc.At present, MOCVD uniquely can prepare GaN base high brightness LED epitaxial wafer and for the growing technology of large-scale production at present.Existing GaN base LED epitaxial wafer is all before growth p-GaN layer, and the thin p-AlGaN electronic barrier layer of the one deck of first growing is to prevent more electronics overflow under large electric current.But the problem that p-AlGaN layer exists is mainly manifested in:
1, due to GaN sill hole effective mass (1.1 m
0) higher than effective mass (0.2 m of electronics
0), therefore, electronics just more easily passes through the quantum well layer that active layer enters active layer top, even overflow active layer and enter p-GaN layer, on the contrary, hole just the more difficult active layer that reaches near the quantum well of n-GaN side.The use of AlGaN electronic barrier layer is intended to block electrons overflow and improves charge carrier recombination rate, but has but further stopped the injection in hole.
2, p-AlGaN electronic barrier layer has reduced the injection efficiency in hole, causes the electron hole CONCENTRATION DISTRIBUTION in single wavelength LED active area inhomogeneous, and mixes in Multiple Quantum Well LED at two blue light wavelengths, and the luminous intensity of two kinds of traps is more unbalanced.
Though 3, the increase of p-AlGaN electronic barrier layer Al component energy block electrons overflow, but the polarized electric field that GaN builds between layer and p-AlGaN electronic barrier layer also further strengthens, last builds the potential barrier of layer to have reduced on the contrary conduction band place, has weakened the restriction to electronics under large electric current.
4, the hole concentration of the p-AlGaN electronic barrier layer in GaN base LED epitaxial wafer is at 5 x 10
17cm
-3left and right, even lower.And free electronic concentration approximately 5 x 10 of N-shaped GaN layer in epitaxial wafer
18cm
-3.How to obtain high hole concentration p-AlGaN layer, thereby increase the compound of electronics and hole in quantum well, for GaN base LED, seem and be even more important, this is also problem very important and difficult in GaN Material growth, is the key of raising GaN base LED performance.
5, because the hole concentration of p-AlGaN layer is low, the resistance that p-type layer and pn make friends with near interface is very large, when LED works, can produce amount of heat, causes LED junction temperature to raise, and shortens the useful life of LED.Although the theoretical life-span of GaN base LED can reach more than 100,000 hours, the life-span is about 1～20,000 hour, even shorter at present.The p-type AlGaN layer that obtains high hole concentration is also key one ring that obtains long-life LED.
At present, the white light LEDs scheme extensively adopting has two kinds: (1) take InGaN base blue light or purple LED is basis, realizes the white light LEDs of changing by fluorescent material; (2) white light LEDs of multi-chip colour mixture.The former major defect is that inorganic fluorescent powder is generally faced with the shortcomings such as the low and color rendering index (CRI) of photic conversion efficiency is poor.And the latter due to luminous all from LED, therefore, cost of manufacture is high, driving is complicated, in addition, the difference of aging characteristics between three kinds of color LED, often causes variable color in luminescence process.Single chip white light LED without fluorescent material has been reported, and is mainly the LED of two or three InGaN/GaN multi-quantum pit structure that grows successively in same Sapphire Substrate, thereby regulates In component to realize the transmitting synthesize white light from blue light to gold-tinted.But, for its luminous efficiency of GaN base luminescent device, generally the efficiency within the scope of 400 ~ 500 nm is higher, along with emission wavelength increases to green glow direction, GaN base LED luminous efficiency reduce gradually, be mainly extremely difficult because realize the InGaN film of high In ingredient.The encapsulation scheme that current blue light adds YAG:Ce gold-tinted fluorescent material occupies the main share in white light LEDs market.The white light LEDs that adds YAG:Ce fluorescent powder packaging for single blue chip has high color rendering index when high color temperature, and when low colour temperature, along with its color rendering that weakens of blue emission intensity reduces gradually, when colour temperature is during lower than 5500K, colour developing is generally lower than 70.And from color rendering index formula:
(
it is the spectral radiance factor of 1 ~ No. 8 test look, 8 kinds of colors such as green, light blue, the purplish blue color of corresponding light bois de rose, dull gray yellow, saturated yellow green, medium yellow green, pale blue, light red purple respectively): if the yellow emission spectrum of maintenance YAG:Ce fluorescence is constant, suitably increase the royal purple light of LED chip and the transmitting of blue green light part, can increase equally the color rendering index of white light LEDs.For the current problem of preparing the existing chip design of White LED with high color rendering property, the method for packing of the two blue light wavelength luminescence chips of Design and manufacture GaN base and White LED with high color rendering property thereof seems and is even more important.
Summary of the invention
The object of the present invention is to provide two blue light wavelength devices of GaN base of a kind of structure novel and preparation method thereof, and become white light LEDs to improve the color rendering of white light with gold-tinted fluorescent powder packaging this pair of blue light wavelength chip.In two blue light wavelength LED, removed p-AlGaN layer and mixed between Multiple Quantum Well active layer and n-GaN and introduce n-AlGaN layer at InGaN/GaN.Thereby improved the injection efficiency in hole, suppressed better electronics overflow, greatly improved the luminous efficiency of two blue light wavelength LED, and made two kinds of quantum well radiation balances.
Optimum efficiency of the present invention is realized by following proposal:
The structure of the two blue light wavelength epitaxial wafers of this GaN base, from substrate, is followed successively by GaN resilient coating, GaN intrinsic layer, n-GaN layer, antisymmetry n-AlGaN layer, high In ingredient Multiple Quantum Well, low In component Multiple Quantum Well and p-GaN layer.Its feature is to remove traditional p-AlGaN electronic barrier layer and introduces antisymmetry n-AlGaN layer between mixing Multiple Quantum Well active layer and n-GaN.Removing of P-AlGaN layer improves the injection efficiency in hole greatly, and the introducing of n-AlGaN layer is more effective, must suppress electronics overflow, thereby cause electron hole concentration to be uniformly distributed in active area, improve luminous efficiency, be conducive to the spectrum-stable of two blue light wavelength LED.
The alms giver of above-mentioned antisymmetry n-AlGaN layer is Si, and thickness is 10～20 nm, and the component of Al is 8～20%.
The alms giver of said n-GaN layer is Si, and p-type GaN layer is mixed with acceptor Mg.
Above-mentioned high In ingredient Multiple Quantum Well and low In component Multiple Quantum Well are respectively the In in 2 ~ 3 cycles
xga
1-xthe In in N/GaN and 2 ~ 3 cycles
yga
1-yn/GaN, wherein In
xga
1-xthe luminous of N/GaN Multiple Quantum Well is blue green light, and emission peak is at 460 ~ 480 nm, and In
yga
1-ythe luminous of N/GaN Multiple Quantum Well is royal purple light, and emission peak is at 430 ~ 450 nm.
The preparation method of this GaN base dual wavelength LED epitaxial wafer, realizes by MOCVD technology, comprises the following steps:
(1) adopt the AlGaInN based material special-purpose MOCVD that grows, be warming up to 1000～1100 ℃ of baking substrates 5～10 minutes.
(2) be cooled to 480 ℃, the GaN low temperature resilient coating that is 30nm at Grown thickness;
(3) be warming up to 1050 ℃, growth thickness is the not Doped GaN layer of 2 μ m;
(4) the n-GaN layer of growth thickness 1.0 μ m～3.0 μ m at the temperature of 1000 ℃～1100 ℃.
(5) at the temperature of 1050 ℃, growth thickness is the antisymmetry n-AlGaN layer of 10～20 nm;
(6) cool the temperature to 600 ℃～800 ℃, growth mixes the active layer of Multiple Quantum Well, is grown to respectively successively the In in 2 ~ 3 cycles
xga
1-xthe In in N/GaN and 2 ~ 3 cycles
yga
1-yn/GaN, wherein In
xga
1-xthe luminous of N/GaN Multiple Quantum Well is blue green light, and emission peak is at 460 ~ 480 nm, and In
yga
1-ythe luminous of N/GaN Multiple Quantum Well is royal purple light, and emission peak is at 430 ~ 450 nm.
(7) the thick p-GaN layer of growth thickness 100～200 nm at the temperature of 1000 ℃～1100 ℃.
Compared with prior art, the present invention has following beneficial effect:
1, improved the injection efficiency in hole and suppressed better electronics and overflow, electron hole concentration uniformity and the luminous efficiency of active area are all greatly enhanced.
2, the spectrum that two kinds of different quantum well are sent is more stable under different electric currents, and along with the increase of electric current can synchronously increase substantially.
Accompanying drawing explanation
Fig. 1 (a) and (b) be respectively the epitaxial structure schematic diagram of two blue light wavelength LED of traditional two blue light wavelength LED and antisymmetry n-AlGaN layer.
Fig. 2 is that two blue chips add YAG:Ce fluorescent powder packaging structural representation.
Fig. 3 is the utilizing emitted light spectrogram that two blue light wavelength chips of antisymmetry n-AlGaN layer add the white light LEDs of YAG:Ce fluorescent powder packaging.
Embodiment
Provide following description, so that those skilled in the art can manufacture and use the present invention, and these descriptions are to provide under the background of concrete application and demand.The various modifications of disclosed embodiment will be apparent to those skilled in the art, and in the situation that not leaving Spirit Essence of the present invention and scope, the General Principle limiting here can be applied in other embodiment and application.Therefore, the invention is not restricted to shown embodiment, but consistent with the maximum magnitude of claim.
The backing material of existing GaN base LED epitaxial wafer structure can adopt sapphire, SiC, Si, GaN etc.Low temperature buffer layer can adopt low temperature GaN layer or low temperature AI N layer etc.Not low temperature growth buffer layer and not Doped GaN layer when adopting GaN to be substrate.Multi-quantum pit structure has InGaN/GaN structure, InGaN/AlGaN structure, In
xga
1-xn/In
yga
1-yn structure etc.In epitaxial slice structure, can not grow n-AlGaN layer or p-AlGaN layer, or n-AlGaN layer and p-AlGaN layer are not all grown.
Fig. 1 (a) is shown in by two blue light wavelength LED epitaxial slice structure schematic diagrames traditional in this patent.Its structure is followed successively by low In component quantum well, p-AlGaN electronic barrier layer and the p-GaN layer in the high In ingredient quantum well in substrate, GaN resilient coating, GaN intrinsic layer, n-GaN layer, 2 ~ 3 cycles, 2 ~ 3 cycles from bottom to up.The structure of novel GaN base dual wavelength epitaxial wafer is as shown in Fig. 1 (b), and it is removed traditional p-AlGaN electronic barrier layer and introduce antisymmetry n-AlGaN layer between mixing Multiple Quantum Well active layer and n-GaN.
Its preparation method is:
(1) adopt the special-purpose MOCVD of GaN, be warming up to 1000 ℃ and under atmosphere of hydrogen, toast substrate 10 minutes;
(2) being cooled to 480 ℃, is the GaN low temperature resilient coating of 30 nm at Grown thickness;
(3) be warming up to 1050 ℃, growth thickness is the not Doped GaN layer of 2 μ m;
(4) at the temperature of 1050 ℃, growth thickness is the n-GaN:Si layer of 2 μ m;
(5) at the temperature of 1050 ℃, growth thickness is the n-Al of 15 nm
0.15ga
0.85n:Si layer;
(6) cool the temperature to the In in 700 ℃ of two cycles of growing respectively
0.18ga
0.82the In in N/GaN quantum well and two cycles
0.12ga
0.88n/GaN quantum well, builds layer and trap layer thickness and is respectively 10 nm and 3 nm;
(7) at the temperature of 600 ℃, growth thickness is that the hole concentration of 200 nm is 5x10
17cm
-3p-GaN:Mg layer.
(8) epitaxial wafer is prepared to the chip that is of a size of 300 μ m x 300 μ m through the chip preparing process of the standards such as photoetching, burn into ICP etching, electrode evaporation, alloy, grinding, scribing, sliver, test and sorting.
(9) technique such as two blue light wavelength chips and package support die bond, baking and bonding wire, and the techniques such as YAG:Ce fluorescent material and epoxy resin or silica gel mixing, stirring and degasification, then by YAG:Ce fluorescent material and epoxy resin or silica-gel mixture point glue to the support after die bond bonding wire, and further the white light LEDs that two blue light wavelength chips excite YAG:Ce fluorescent material is prepared in baking sizing.Fig. 2 represents the LED schematic diagram of two blue chips and YAG:Ce fluorescent powder packaging, and Fig. 3 is the utilizing emitted light spectrogram of corresponding white light LEDs.Wherein: 440 nm peaks are from In
0.12ga
0.88the transmitting of N/GaN Multiple Quantum Well, during 475 nm peak from In
0.18ga
0.82the transmitting of N/GaN Multiple Quantum Well, 575 nm are the transmittings from two blue-light excited YAG:Ce fluorescent material.
Claims (9)
1. two blue light wavelength LED epitaxial wafers of GaN base, its structure, from substrate, is followed successively by GaN resilient coating, GaN intrinsic layer, n-GaN layer, antisymmetry n-AlGaN layer, high In ingredient Multiple Quantum Well, low In component Multiple Quantum Well and p-GaN layer;
Its active layer that mixes Multiple Quantum Well, from substrate to p-GaN direction, is followed successively by the In in 2 ~ 3 cycles
xga
1-xthe In in N/GaN quantum well and 2 ~ 3 cycles
yga
1-yN/GaN quantum well, wherein In
xga
1-xthe luminous of N/GaN Multiple Quantum Well is blue green light, and emission peak is at 460 ~ 480 nm, and In
yga
1-ythe luminous of N/GaN Multiple Quantum Well is royal purple light, and emission peak is at 430 ~ 450 nm.
2. two blue light wavelength LED epitaxial wafers of GaN base according to claim 1, the electron concentration that it is characterized in that described n-AlGaN layer is 1 * 10
18～5 * 10
18cm
-3.
3. the two blue light wavelength LED epitaxial wafers of GaN base according to claim 1 and 2, is characterized in that described n-AlGaN layer alms giver is Si.
4. two blue light wavelength LED epitaxial wafers of GaN base according to claim 1, the thickness that it is characterized in that described n-AlGaN layer is 10 nm～20 nm, and the component of Al is 8%～20%.
5. the two blue light wavelength LED epitaxial wafers of GaN base according to claim 1, is characterized in that p-GaN layer is mixed with acceptor Mg.
6. two blue light wavelength LED epitaxial wafers of GaN base according to claim 1, the material that it is characterized in that described substrate is a kind of in sapphire, silicon, SiC or GaN.
7. the preparation method of the two blue light wavelength LED epitaxial wafers of a GaN base as claimed in claim 1, it is characterized in that comprising the following steps: to adopt AlGaInN based material growth MOCVD, at substrate successively growing GaN resilient coating, GaN intrinsic layer, n-GaN layer, antisymmetry n-AlGaN layer, the In in 2 ~ 3 cycles
xga
1-xthe In in N/GaN quantum well and 2 ~ 3 cycles
yga
1-yN/GaN quantum well, and p-type GaN.
8. a white light LEDs, is characterized in that being combined and being packaged into gold-tinted fluorescent material by the two blue light wavelength LED epitaxial wafers of GaN base claimed in claim 1.
9. white light LEDs according to claim 8, is characterized in that, the scope of its emission peak is at 550 ~ 580nm, and described gold-tinted phosphor material powder is a kind of in YAG:Ce, silicate, aluminate or nitride.
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| CN103904178B (en) * | 2014-04-11 | 2016-08-17 | 浙江大学 | Quantum dot light emitting device |
| CN109841711A (en) * | 2019-02-01 | 2019-06-04 | 中国科学院半导体研究所 | White light LEDs and preparation method thereof based on non-radiative resonance energy transfer mechanism |
| CN113394313B (en) * | 2020-03-13 | 2022-12-27 | 华为技术有限公司 | LED chip, manufacturing method thereof, display module and terminal |
| WO2022143028A1 (en) * | 2020-12-30 | 2022-07-07 | 芯思杰技术(深圳)股份有限公司 | Quantum well structure, chip processing method, chip, and laser |
| CN113241340B (en) * | 2021-05-08 | 2022-09-02 | 上海煜珑电子科技有限公司 | Optical device and method for manufacturing the same |
| WO2023279241A1 (en) * | 2021-07-05 | 2023-01-12 | 重庆康佳光电技术研究院有限公司 | Led chip, led array and electronic device |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1885573A (en) * | 2005-06-23 | 2006-12-27 | 华南师范大学 | GaN-based LED extension sheet and its preparation method |
| CN101459216A (en) * | 2008-12-29 | 2009-06-17 | 上海蓝光科技有限公司 | Bluelight LED in asymmetric multiple quanta pit structure and manufacturing process thereof |
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| KR101459752B1 (en) * | 2007-06-22 | 2014-11-13 | 엘지이노텍 주식회사 | Semiconductor light emitting device and fabrication method thereof |
| KR20090002241A (en) * | 2007-06-25 | 2009-01-09 | 엘지이노텍 주식회사 | Light emitting device and fabrication method thereof |
| US20100006873A1 (en) * | 2008-06-25 | 2010-01-14 | Soraa, Inc. | HIGHLY POLARIZED WHITE LIGHT SOURCE BY COMBINING BLUE LED ON SEMIPOLAR OR NONPOLAR GaN WITH YELLOW LED ON SEMIPOLAR OR NONPOLAR GaN |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN1885573A (en) * | 2005-06-23 | 2006-12-27 | 华南师范大学 | GaN-based LED extension sheet and its preparation method |
| CN101459216A (en) * | 2008-12-29 | 2009-06-17 | 上海蓝光科技有限公司 | Bluelight LED in asymmetric multiple quanta pit structure and manufacturing process thereof |
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