CN1885572A - GaN-based LED extension sheet and its preparation method - Google Patents

GaN-based LED extension sheet and its preparation method Download PDF

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CN1885572A
CN1885572A CNA200510035444XA CN200510035444A CN1885572A CN 1885572 A CN1885572 A CN 1885572A CN A200510035444X A CNA200510035444X A CN A200510035444XA CN 200510035444 A CN200510035444 A CN 200510035444A CN 1885572 A CN1885572 A CN 1885572A
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resilient coating
epitaxial wafer
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CN100392881C (en
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李述体
范广涵
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South China Normal University
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South China Normal University
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Abstract

The related GaN-base LED epitaxial sheet comprises: from bottom to top, a substrate, a n-type layer, a quantum trap, a limit layer, a buffer layer, and a p-type layer as GaP layer with hole concentration as 2*1018~6*1018cm-3. This invention can reduce p-type layer resistance, overcomes the defects of small GaP forbidden band and limit effect, and improves the GaN-base LED performance obviously.

Description

A kind of GaN base LED epitaxial wafer and preparation method thereof
Technical field
The present invention relates to the GaN base LED epitaxial wafer in semiconductor photoelectronic device field, particularly a kind of new structure and preparation method thereof.
Background technology
GaN based high-brightness light-emitting diode (LED) is the forward position and the focus of present global optoelectronic areas research and industry.GaN base LED preparation will be through the growth of LED epitaxial wafer, led chip preparation and three key links of LED encapsulation.Wherein the preparation of LED epitaxial wafer is the core technology of LED, and it plays a major role to the performance level of LED.
It is p type layer main body that existing GaN base LED epitaxial wafer all adopts GaN, and the very thin AlGaN layer of growing before p type GaN growth sometimes is to increase the constraint to charge carrier.GaN base LED and laser (LD) all adopt this structure at present.The problem that p type GaN exists mainly shows:
1, the GaN energy gap is up to 3.4eV, acceptor impurity ionization energy height, and the p type layer that obtains high hole concentration is very difficult.The hole concentration of p type GaN generally is no more than 1 * 10 18Cm -3, under this concentration, hole mobility is generally less than 10cm 2/ Vs.And in order to reduce p type layer resistance, LED epitaxial wafer p type layer thickness is no more than 0.3 μ m, so more is difficult to obtain the p type layer of high hole concentration.P type layer hole concentration in the GaN base LED epitaxial wafer is 5 * 10 17Cm -3About, even lower.And the free electronic concentration about 5 * 10 of n type GaN layer in the epitaxial wafer 18Cm -3, mobility generally is higher than 100cm 2/ Vs.How to obtain high hole concentration p type layer, electronics and hole is compound in the increase quantum well, and LED seems particularly important for the GaN base, also is very important and difficult problem in the growth of GaN material, is the key that improves the LED performance.
2, because the p type GaN layer hole concentration of GaN base LED epitaxial wafer is little, and p type layer thickness is less than 0.3 μ m, the very difficult expansion of electric current.Based on this reason, generally p type electrode is made large-area current extending.Because GaN base LED epitaxial wafer thickness is generally less than 4 μ m, the overwhelming majority is luminous to be to appear from p type layer.And p type electrode unavoidably has absorption to light, causes the led chip external quantum efficiency not high, greatly reduces the luminous efficiency of LED.The ripe at present transmissivity of p type oxidation Ni/Au electrode from the purple light to the green light band is about 70%.Adopt the ITO layer higher as the transmissivity of current extending, but cause LED voltage higher, the life-span also is affected.
3, because the p type GaN layer thickness in the GaN base LED epitaxial wafer is little.Simultaneously, appear from p type layer in order to make more light, p type oxidation Ni/Au contact electrode can not be done very thickly, generally about 60 /60 .Under applied voltage, the diffusion effect in electronics and hole still is undesirable, and a large amount of holes are passed under metal pad, and a large amount of electronics and hole are compound under pad.And the luminous very major part under the metal pad can not transmit, and causes the LED luminous efficiency not high.Simultaneously, because the electric current diffusion is inhomogeneous, some regional current densities are very big, influence the LED life-span.
4, because the hole concentration of p type GaN is low, and the resistance that p type layer and pn make friends with near interface is very big, can produce a large amount of heats when LED works, cause the LED junction temperature to raise, shorten the useful life of LED.Although the theoretical life-span of GaN base LED can reach more than 100,000 hours, at present the life-span about 1～20,000 hour, even shorter.The p type layer that obtains high hole concentration also is key one ring that obtains long-life LED.
Summary of the invention
The object of the present invention is to provide a kind of GaN base LED epitaxial wafer with new structure and preparation method thereof, its structure is followed successively by substrate, n type layer, quantum well, limiting layer, resilient coating and p type layer from bottom to up.This structure is replaced p type GaN layer with the GaP layer of a high hole concentration, and the limiting layer of growing between resilient coating and quantum well.Adopting high hole concentration GaP layer to overcome factors such as the low and p type layer of the p type GaN hole concentration of original GaN base LED is thin, to cause under the applied voltage hole to be injected few, and electric current spreads uneven shortcoming.Simultaneously, limiting layer can overcome because little, little to the restriction in electronics in the quantum well and the hole shortcoming of GaP energy gap strengthens the restriction to electronics in the quantum well and hole greatly.
The invention has the beneficial effects as follows and realize by following proposal:
The square successively from bottom to up substrate of the structure of the GaN base LED epitaxial wafer that this is novel, n type layer, quantum well, limiting layer, resilient coating and p type layer are characterized in that p type layer is that hole concentration is 2 * 10 18～6 * 10 18Cm -3Mix the GaP layer of being led, and between resilient coating and quantum well growth one limiting layer.P type layer hole concentration increases, and can reduce p type layer resistance, and applied voltage can increase the injection in hole down, and makes the electric current diffusion more even.Simultaneously, limiting layer can overcome because little, little to the restriction in electronics in the quantum well and the hole shortcoming of GaP energy gap strengthens that greatly electronics in the quantum well and hole are provided constraints, electronics and hole is compound in the increase quantum well, thereby obviously improves the performance of GaN base LED.
The resilient coating of growing between above-mentioned limiting layer and the p type GaP layer can be the GaP resilient coating, perhaps AlP resilient coating, perhaps growing GaN/GaP compound buffer layer, or AlP/GaP compound buffer layer.The effect of resilient coating is the influence that reduces lattice mismatch between GaN and the GaP, thereby obtains high-quality GaP layer.
Limiting layer between above-mentioned resilient coating and the quantum well is n type GaN layer or n type AlGaN layer or n type InGaN layer or compound limiting layer of n type InGaN/GaN or the compound limiting layer of n type GaN/AlGaN, and the thickness of limiting layer is 0.02 μ m～0.1 μ m.Or p type GaN layer or p type AlGaN layer or p type InGaN layer or compound limiting layer of p type InGaN/GaN or the compound limiting layer of p type GaN/AlGaN, the thickness of limiting layer is 0.02 μ m～0.2 μ m.
The master that is subjected to of above-mentioned p type GaP layer is Mg or Zn, and thickness is 0.02 μ m～10.0 μ m.
Said n type layer is n type GaN, or n type GaN and AlGaN, is mixed with alms giver Si.
Said n type limiting layer is n type layer or a plain n type layer of mixing alms giver Si.
Above-mentioned p type limiting layer is to mix the p type layer that is subjected to main Mg.
The preparation method of this GaN base LED epitaxial wafer realizes by the MOCVD technology, comprises the following steps:
1) adopts the AlGaInN based material special-purpose MOCVD that grows, be warming up to 1000～1100 ℃ of baking substrates 5～10 minutes.
2) growth thickness is the n type GaN layer of 1.0 μ m～3.0 μ m under 1000 ℃～1100 ℃ temperature.
3) cool the temperature to 600 ℃～800 ℃, grown quantum well structure, periodicity are 1～10.
4) at n type GaN layer or AlGaN layer or InGaN layer or compound limiting layer of n type InGaN/GaN or the compound limiting layer of n type GaN/AlGaN of 750 ℃～1100 ℃ growth thickness 0.02 μ m～0.1 μ m; Perhaps at p type GaN layer or p type AlGaN layer or p type InGaN layer or compound limiting layer of p type InGaN/GaN or the compound limiting layer of p type GaN/AlGaN of 750 ℃～1100 ℃ growth thickness 0.02 μ m～0.2 μ m.
5) epitaxial wafer is taken out, and put into the AlGaInP based material special-purpose mocvd growth chamber of growing;
6) under atmosphere of hydrogen, under 500 ℃～800 ℃ temperature, handled substrate 2～10 minutes, then at 300 ℃～500 ℃ grown buffer layers.
7) growth thickness is that the hole concentration of 0.2 μ m～10.0 μ m is 2 * 10 under 500 ℃～700 ℃ temperature 18Cm -3～6 * 10 18Cm -3P type GaP layer.
Compared with prior art, advantage of the present invention is:
1, adopting the GaP of high hole concentration is p type layer, and applied voltage can increase the injection in hole down, improves luminous efficiency.
2, adopting the GaP of high hole concentration is p type layer, reduces p type layer resistance greatly, can suitably increase p type layer thickness, makes the electric current diffusion evenly, and need not make the large-area current extending that light is had absorption, can reduce luminous under the metal pad simultaneously.Increase the LED external quantum efficiency, improve luminous efficiency.
3, adopt limiting layer, can overcome because little, little to the restriction in electronics in the quantum well and the hole shortcoming of GaP energy gap strengthens that greatly electronics in the quantum well and hole are provided constraints, electronics and hole is compound in the increase quantum well, thereby obviously improves the performance of GaN base LED.
Description of drawings
Fig. 1 is the GaN base LED epitaxial wafer structural representation of embodiment 1, example 2, example 11;
Fig. 2 is the GaN base LED epitaxial wafer structural representation of embodiment 3 and example 4;
Fig. 3 is the GaN base LED epitaxial wafer structural representation of embodiment 5 and example 6;
Fig. 4 is the GaN base LED epitaxial wafer structural representation of embodiment 7 and example 8;
Fig. 5 is the GaN base LED epitaxial wafer structural representation of embodiment 9 and example 10;
Fig. 6 is existing GaN base LED epitaxial wafer structural representation.
Embodiment
Existing GaN base LED epitaxial wafer structural representation is seen Fig. 6.Wherein, backing material can adopt sapphire, SiC, Si, GaN or the like.Low temperature buffer layer can adopt low temperature GaN layer, low temperature AI N layer, low temperature GaN/AlN layer or the like, not low temperature growth buffer layer and not Doped GaN layer when adopting GaN for substrate.Quantum well can adopt single quantum well, also can adopt Multiple Quantum Well, and quantum well structure has InGaN/GaN structure, GaN/AlGaN structure, InGaN/AlGaN structure, In xGa 1-xN/In yGa 1-yN structure or the like.Not growing n-type AlGaN layer or p type AlGaN layer in the epitaxial slice structure, or n type AlGaN layer and p type AlGaN layer are not all grown.
Embodiment 1
The structure of the GaN base LED epitaxial wafer that this is novel is followed successively by substrate, low temperature buffer layer, not Doped GaN layer, n type GaN:Si layer, n type AlGaN:Si layer, quantum well, n type GaN limiting layer, resilient coating, p type GaP:Mg layer as shown in Figure 1 from bottom to up.
Its preparation method is:
1) adopts the special-purpose MOCVD of GaN, be warming up to 1000 ℃ and under atmosphere of hydrogen, toasted substrate 10 minutes;
2) be cooled to 480 ℃, growth thickness is the GaN low temperature resilient coating of 30nm on substrate;
3) be warming up to 1050 ℃, growth thickness is the not Doped GaN layer of 2.0 μ m;
4) growth thickness is the n type GaN:Si layer of 2.0 μ m under 1050 ℃ temperature;
5) growth thickness is the n type Al of 0.1 μ m under 1050 ℃ temperature 0.1Ga 0.9The N:Si layer;
6) cool the temperature to 700 ℃ of growth In xGa yThe N/GaN multi-quantum pit structure, the thickness of InGaN trap layer is 3nm, and the thickness that GaN builds layer is 8nm, and the In component of InGaN trap layer is 0.16, and the quantum well periodicity is 10;
7) the n type GaN layer of 900 ℃ of growth thickness 0.05 μ m of intensification;
8) epitaxial wafer is taken out, and put into the AlGaInP based material special-purpose mocvd growth chamber of growing;
9) under the atmosphere of hydrogen, with 650 ℃ Temperature Treatment epitaxial wafers 5 minutes, then at the GaP of 500 ℃ of growth thickness 20nm resilient coating;
10) reaction chamber temperature rises to 600 ℃, and under atmosphere of hydrogen, heat treatment resilient coating 5 minutes makes the resilient coating recrystallization;
11) hole concentration of growth thickness 5.0 μ m is 6 * 10 under 600 ℃ the temperature 18Cm -3The GaP:Mg layer.
This structure can increase the injection in hole under the applied voltage, and it is whole more even that electric current is expanded, and improves the LED performance.This preparation method is suitable for making the blue-ray LED epitaxial wafer.Adopt this new structure, the luminous power of 460nm blue-ray LED is increased to more than 6 milliwatts by 4 milliwatts.
Embodiment 2
The structure of the GaN base LED epitaxial wafer that this is novel is followed successively by substrate, low temperature buffer layer, not Doped GaN layer, n type GaN:Si layer, n type AlGaN:Si layer, quantum well, p type GaN limiting layer, resilient coating, p type GaP:Mg layer as shown in Figure 1 from bottom to up.
Its preparation method is:
1) adopts the special-purpose MOCVD of GaN, be warming up to 1000 ℃ and under atmosphere of hydrogen, toasted substrate 10 minutes;
2) be cooled to 480 ℃, growth thickness is the GaN low temperature resilient coating of 30nm on substrate;
3) be warming up to 1050 ℃, growth thickness is the not Doped GaN layer of 2.0 μ m;
4) growth thickness is the n type GaN:Si layer of 2.0 μ m under 1050 ℃ temperature;
5) growth thickness is the n type Al of 0.1 μ m under 1050 ℃ temperature 0.1Ga 0.9The N:Si layer;
6) cool the temperature to 700 ℃ of growth In xGa yThe N/GaN multi-quantum pit structure, the thickness of InGaN trap layer is 3nm, and the thickness that GaN builds layer is 8nm, and the In component of InGaN trap layer is 0.18, and the quantum well periodicity is 10;
7) at the p type GaN of 900 ℃ of growth thickness, 0.2 μ m layer;
8) epitaxial wafer is taken out, and put into the AlGaInP based material special-purpose mocvd growth chamber of growing;
9) under atmosphere of hydrogen, with 650 ℃ Temperature Treatment epitaxial wafers 5 minutes, then at the GaP:Mg of 500 ℃ of growth thickness 20nm resilient coating;
10) rising reaction chamber temperature to 600 ℃, under atmosphere of hydrogen, heat treatment resilient coating 5 minutes makes the resilient coating recrystallization;
11) hole concentration of growth thickness 3.0 μ m is 6 * 10 under 600 ℃ temperature 18Cm -3The GaP:Mg layer.
This structure can increase the injection in hole under the applied voltage, and it is whole more even that electric current is expanded, and growing p-type GaN limiting layer can be adjusted to the p-n junction of LED near the quantum well, improves the LED performance.This preparation method is suitable for making the blue-ray LED epitaxial wafer.Adopt this new structure, the luminous power of 470nm blue-ray LED is increased to more than 5 milliwatts by 3 milliwatts.
Embodiment 3
The structure of the GaN base LED epitaxial wafer that this is novel is followed successively by substrate, low temperature buffer layer, not Doped GaN layer, n type GaN:Si layer, quantum well, n type InGaN limiting layer, resilient coating, p type GaP:Mg layer as shown in Figure 2 from bottom to up.
Its preparation method is:
1) adopts the special-purpose MOCVD of GaN, be warming up to 1050 ℃ and under atmosphere of hydrogen, toasted substrate 8 minutes;
2) be cooled to 510 ℃, growth thickness is the GaN low temperature resilient coating of 25nm on substrate;
3) be warming up to 1000 ℃, growth thickness is the not Doped GaN layer of 2.5 μ m;
4) growth thickness is the n type GaN:Si layer of 1.0 μ m under 1000 ℃ temperature;
5) cool the temperature to 600 ℃, growing InGaN/GaN multi-quantum pit structure, the thickness of InGaN trap layer is 4nm, and the thickness that GaN builds layer is 6nm, and the In component of InGaN trap layer is 0.25, and the quantum well periodicity is 5;
6) at the n type InGaN of 750 ℃ of growth thickness, 0.02 μ m layer;
7) epitaxial wafer is taken out, and put into the AlGaInP based material special-purpose mocvd growth chamber of growing;
8) under atmosphere of hydrogen, with 500 ℃ Temperature Treatment epitaxial wafer 10 clocks, then at the GaP of 400 ℃ of growth thickness 35nm resilient coating;
9) rising reaction chamber temperature to 650 ℃, under atmosphere of hydrogen, heat treatment resilient coating 10 minutes makes the resilient coating recrystallization;
10) hole concentration of growth thickness 0.2 μ m is 4 * 10 under 500 ℃ temperature 18Cm -3The GaP:Mg layer.
This structure can increase the injection in hole under the applied voltage, and reduces the forward voltage of LED, and the growth temperature of InGaN limiting layer is lower, and low limiting layer growth temperature can reduce the destruction to quantum well.This preparation method is suitable for making the green light LED epitaxial wafer.Adopt this new structure, the luminous power of 520nm green light LED is increased to more than 1.8 milliwatts by 1.2 milliwatts.
Embodiment 4
The structure of the GaN base LED epitaxial wafer that this is novel is followed successively by substrate, low temperature buffer layer, not Doped GaN layer, n type GaN:Si layer, quantum well, p type InGaN limiting layer, resilient coating, p type GaP:Mg layer as shown in Figure 2 from bottom to up.
Its preparation method is:
1) adopts the special-purpose MOCVD of GaN, be warming up to 1050 ℃ and under atmosphere of hydrogen, toasted substrate 8 minutes;
2) be cooled to 510 ℃, growth thickness is the GaN low temperature resilient coating of 25nm on substrate;
3) be warming up to 1000 ℃, growth thickness is the not Doped GaN layer of 2.5 μ m;
4) growth thickness is the n type GaN:Si layer of 1.0 μ m under 1000 ℃ temperature;
5) cool the temperature to 600 ℃, growing InGaN/GaN multi-quantum pit structure, the thickness of InGaN trap layer is 4nm, and the thickness that GaN builds layer is 6nm, and the In component of InGaN trap layer is 0.25, and the quantum well periodicity is 5;
6) at the p type InGaN of 750 ℃ of growth thickness, 0.05 μ m layer;
7) epitaxial wafer is taken out, and put into the AlGaInP based material special-purpose mocvd growth chamber of growing;
8) under atmosphere of hydrogen, with 500 ℃ Temperature Treatment epitaxial wafer 10 clocks, then at the GaP:Mg of 400 ℃ of growth thickness 35nm resilient coating;
9) rising reaction chamber temperature to 650 ℃, under atmosphere of hydrogen, heat treatment resilient coating 10 minutes makes the resilient coating recrystallization;
10) hole concentration of growth thickness 0.5 μ m is 4 * 10 under 500 ℃ temperature 18Cm -3The GaP:Mg layer.
This structure can increase the injection in hole under the applied voltage, and reducing the forward voltage of LED, growing p-type InGaN limiting layer can be adjusted to the p-n junction of LED near the quantum well, the growth temperature of InGaN limiting layer is lower, and low limiting layer growth temperature can reduce the destruction to quantum well.This preparation method is suitable for making the green light LED epitaxial wafer.Adopt this new structure, the luminous power of 520nm green light LED is increased to more than 1.8 milliwatts by 1.2 milliwatts.
Embodiment 5
The structure of the GaN base LED epitaxial wafer that this is novel is followed successively by substrate, low temperature buffer layer, not Doped GaN layer, n type GaN:Si layer, n type AlGaN:Si layer, quantum well, n type AlGaN limiting layer, resilient coating, p type GaP:Zn layer as shown in Figure 3 from bottom to up.
Its preparation method is:
1) adopts the special-purpose MOCVD of GaN, be warming up to 1100 ℃ and under atmosphere of hydrogen, toasted substrate 5 minutes;
2) be cooled to 550 ℃, growth thickness is the GaN low temperature resilient coating of 20nm on substrate;
3) be warming up to 1100 ℃, growth thickness is the not Doped GaN layer of 1.5 μ m;
4) growth thickness is the n type GaN:Si layer of 3.0 μ m under 1100 ℃ temperature;
5) growth thickness is the n type Al of 0.05 μ m under 1100 ℃ temperature 0.2Ga 0.8The N:Si layer;
6) cool the temperature to 800 ℃, growing InGaN/GaN multi-quantum pit structure, the thickness of InGaN trap layer is 3nm, and the thickness that GaN builds layer is 10nm, and the In component of InGaN trap layer is 0.14, and the quantum well periodicity is 1;
7) at the n type AlGaN of 1100 ℃ of growth thickness, 0.1 μ m layer;
8) epitaxial wafer is taken out, and put into the AlGaInP based material special-purpose mocvd growth chamber of growing;
9) under atmosphere of hydrogen, with 800 ℃ Temperature Treatment epitaxial wafers 2 minutes, then at the GaP of 300 ℃ of growth thickness 50nm resilient coating;
10) rising reaction chamber temperature to 700 ℃, under atmosphere of hydrogen, heat treatment resilient coating 3 minutes makes the resilient coating recrystallization;
11) hole concentration of growth thickness 10.0 μ m is 2 * 10 under 700 ℃ temperature 18Cm -3The GaP:Zn layer.
This structure has increased the thickness of p type GaP layer, further improves electric current and expands whole uniformity, has improved LED epitaxial wafer quality, adopts AlGaN as limiting layer, can make electronics and hole better be limited in quantum well.But the LED epitaxial wafer manufacturing cost of this structure increases.This structure is suitable for making the blue-ray LED epitaxial wafer.Adopt this new structure, the luminous power of 450nm blue-ray LED is increased to more than 5.0 milliwatts by 3.0 milliwatts.
Embodiment 6
The structure of the GaN base LED epitaxial wafer that this is novel is followed successively by substrate, low temperature buffer layer, not Doped GaN layer, n type GaN:Si layer, n type AlGaN:Si layer, quantum well, p type AlGaN limiting layer, resilient coating, p type GaP:Zn layer as shown in Figure 3 from bottom to up.
Its preparation method is:
1) adopts the special-purpose MOCVD of GaN, be warming up to 1100 ℃ and under atmosphere of hydrogen, toasted substrate 5 minutes;
2) be cooled to 550 ℃, growth thickness is the GaN low temperature resilient coating of 20nm on substrate;
3) be warming up to 1100 ℃, growth thickness is the not Doped GaN layer of 1.5 μ m;
4) growth thickness is the n type GaN:Si layer of 3.0 μ m under 1100 ℃ temperature;
5) growth thickness is the n type Al of 0.05 μ m under 1100 ℃ temperature 0.2Ga 0.8The N:Si layer;
6) cool the temperature to 800 ℃, growing InGaN/GaN multi-quantum pit structure, the thickness of InGaN trap layer is 3nm, and the thickness that GaN builds layer is 10nm, and the In component of InGaN trap layer is 0.14, and the quantum well periodicity is 1;
7) at the p type AlGaN of 1100 ℃ of growth thickness, 0.1 μ m layer;
8) epitaxial wafer is taken out, and put into the AlGaInP based material special-purpose mocvd growth chamber of growing;
9) under atmosphere of hydrogen, with 800 ℃ Temperature Treatment epitaxial wafers 2 minutes, then at the GaP of 300 ℃ of growth thickness 50nm resilient coating;
10) rising reaction chamber temperature to 700 ℃, under atmosphere of hydrogen, heat treatment resilient coating 3 minutes makes the resilient coating recrystallization;
11) hole concentration of growth thickness 6.0 μ m is 2 * 10 under 700 ℃ temperature 18Cm -3The GaP:Mg layer.
This structure has increased the thickness of p type GaP layer, further improve electric current and expand whole uniformity, improved LED epitaxial wafer quality, adopt p type AlGaN as limiting layer, can make electronics and hole better be limited in quantum well, and the p-n junction of LED is adjusted near the quantum well.But the LED epitaxial wafer manufacturing cost of this structure increases.This structure is suitable for making the blue-ray LED epitaxial wafer.Adopt this new structure, the luminous power of 450nm blue-ray LED is increased to more than 5.0 milliwatts by 3.0 milliwatts.
Embodiment 7
The structure of the GaN base LED epitaxial wafer that this is novel is followed successively by substrate, n type GaN:Si layer, n type AlGaN:Si layer, quantum well, n type InGaN/GaN limiting layer, resilient coating, p type GaP:Mg layer as shown in Figure 4 from bottom to up.
Its preparation method is:
1) adopts the special-purpose MOCVD of GaN, be warming up to 1100 ℃ and under atmosphere of hydrogen, toasted substrate 10 minutes;
2) growth thickness is the n type GaN:Si layer of 2.0 μ m under 1100 ℃ temperature;
3) growth thickness is the n type Al of 0.05 μ m under 1100 ℃ temperature 0.05Ga 0.95The N:Si layer;
4) cool the temperature to 720 ℃, growing InGaN/GaN multi-quantum pit structure, the thickness of InGaN trap layer is 3nm, and the thickness that GaN builds layer is 8nm, and the quantum well periodicity is 5;
5) at the n type InGaN of 750 ℃ of growth thickness, 0.02 μ m layer;
6) at the n type GaN of 900 ℃ of growth thickness, 0.05 μ m layer;
7) epitaxial wafer is taken out, and put into the AlGaInP based material special-purpose mocvd growth chamber of growing;
8) under atmosphere of hydrogen, with 700 ℃ Temperature Treatment epitaxial wafers 5 minutes, then at the AlP of 500 ℃ of growth thickness 50nm resilient coating;
9) rising reaction chamber temperature to 650 ℃, under atmosphere of hydrogen, heat treatment resilient coating 10 minutes makes the resilient coating recrystallization;
10) hole concentration of growth thickness 5.0 μ m is 6 * 10 under 650 ℃ temperature 18Cm -3The GaP:Mg layer.
This structure adopts the backing material with the GaN lattice constant match, not low temperature growth buffer layer and not Doped GaN layer on this substrate, and adjusted some growth parameter(s)s, further improved LED epitaxial wafer quality.This structure is suitable for making blue light and green light LED epitaxial wafer.Adopt this new structure, the luminous power of 460nm blue-ray LED is increased to more than 6.0 milliwatts by 3.0 milliwatts, and the luminous power of 520nm green light LED is increased to more than 2.2 milliwatts by 1.2 milliwatts.
Embodiment 8
The structure of the GaN base LED epitaxial wafer that this is novel is followed successively by substrate, n type GaN:Si layer, n type AlGaN:Si layer, quantum well, p type InGaN/GaN limiting layer, resilient coating, p type GaP:Mg layer as shown in Figure 4 from bottom to up.
Its preparation method is:
1) adopts the special-purpose MOCVD of GaN, be warming up to 1100 ℃ and under atmosphere of hydrogen, toasted substrate 10 minutes;
2) growth thickness is the n type GaN:Si layer of 2.0 μ m under 1100 ℃ temperature;
3) growth thickness is the n type Al of 0.05 μ m under 1100 ℃ temperature 0.05Ga 0.95The N:Si layer;
4) cool the temperature to 720 ℃, growing InGaN/GaN multi-quantum pit structure, the thickness of InGaN trap layer is 3nm, and the thickness that GaN builds layer is 8nm, and the quantum well periodicity is 5;
5) at the p type InGaN of 750 ℃ of growth thickness, 0.05 μ m layer;
6) at the p type GaN of 900 ℃ of growth thickness, 0.1 μ m layer;
7) epitaxial wafer is taken out, and put into the AlGaInP based material special-purpose mocvd growth chamber of growing;
8) under atmosphere of hydrogen, with 700 ℃ Temperature Treatment epitaxial wafers 5 minutes, then at the AlP of 500 ℃ of growth thickness 50nm resilient coating;
9) rising reaction chamber temperature to 650 ℃, under atmosphere of hydrogen, heat treatment resilient coating 10 minutes makes the resilient coating recrystallization;
10) hole concentration of growth thickness 5.0 μ m is 6 * 10 under 650 ℃ temperature 18Cm -3The GaP:Mg layer.
This structure adopts the backing material with the GaN lattice constant match, not low temperature growth buffer layer and not Doped GaN layer on this substrate, adopt p type InGaN/GaN limiting layer, the p-n junction of LED can be adjusted near the quantum well, further improved LED epitaxial wafer quality.This structure is suitable for making blue light and green light LED epitaxial wafer.Adopt this new structure, the luminous power of 460nm blue-ray LED is increased to more than 6.0 milliwatts by 3.0 milliwatts, and the luminous power of 520nm green light LED is increased to more than 2.2 milliwatts by 1.2 milliwatts.
Embodiment 9
The structure of the GaN base LED epitaxial wafer that this is novel is followed successively by substrate, low temperature buffer layer, not Doped GaN layer, n type GaN:Si layer, n type AlGaN:Si layer, quantum well, n type GaN/AlGaN limiting layer, resilient coating, p type GaP:Mg layer as shown in Figure 5 from bottom to up.
Its preparation method is:
1) adopts the special-purpose MOCVD of GaN, be warming up to 1000 ℃ and under atmosphere of hydrogen, toasted substrate 10 minutes;
2) be cooled to 480 ℃, growth thickness is the GaN low temperature resilient coating of 30nm on substrate;
3) be warming up to 1050 ℃, growth thickness is the not Doped GaN layer of 2.0 μ m;
4) growth thickness is the n type GaN:Si layer of 2.0 μ m under 1050 ℃ temperature;
5) growth thickness is the n type Al of 0.1 μ m under 1050 ℃ temperature 0.1Ga 0.9The N:Si layer;
6) cool the temperature to 700 ℃ of growth In xGa yThe N/GaN multi-quantum pit structure, the thickness of InGaN trap layer is 3nm, and the thickness that GaN builds layer is 8nm, and the In component of InGaN trap layer is 0.14, and the quantum well periodicity is 10;
7) at the n type GaN of 900 ℃ of growth thickness, 0.02 μ m layer;
8) at the n type AlGaN of 1000 ℃ of growth thickness, 0.05 μ m layer;
9) cool the temperature to 480 ℃, growing GaN resilient coating, buffer layer thickness are 20nm
10) prolong sheet and take out, and put into the AlGaInP based material special-purpose mocvd growth chamber of growing;
11) under atmosphere of hydrogen, with 700 ℃ Temperature Treatment epitaxial wafers 5 minutes, then at the GaP of 350 ℃ of growth thickness 20nm resilient coating;
12) rising reaction chamber temperature to 600 ℃, under atmosphere of hydrogen, heat treatment resilient coating 5 minutes makes the resilient coating recrystallization;
13) hole concentration of growth thickness 5.0 μ m is 6 * 10 under 600 ℃ temperature 18Cm -3The GaP:Mg layer.
This structure has adopted the GaN/GaP compound buffer layer, has further reduced the influence of lattice mismatch between GaN and the GaP, thereby obtains high-quality p type GaP layer, and (111) the face double crystal diffraction halfwidth that makes the GaP layer is less than 400 second of arcs.Adopt the compound limiting layer of GaN/AlGaN, electronics and hole in the more effective constraint quantum well of energy, this structure is fit to make the blue-ray LED epitaxial wafer, helps prolonging the LED life-span.
Embodiment 10
The structure of the GaN base LED epitaxial wafer that this is novel is followed successively by substrate, low temperature buffer layer, not Doped GaN layer, n type GaN:Si layer, n type AlGaN:Si layer, quantum well, p type GaN/AlGaN limiting layer, resilient coating, p type GaP:Mg layer as shown in Figure 5 from bottom to up.
Its preparation method is:
1) adopts the special-purpose MOCVD of GaN, be warming up to 1000 ℃ and under atmosphere of hydrogen, toasted substrate 10 minutes;
2) be cooled to 480 ℃, growth thickness is the GaN low temperature resilient coating of 30nm on substrate;
3) be warming up to 1050 ℃, growth thickness is the not Doped GaN layer of 2.0 μ m;
4) growth thickness is the n type GaN:Si layer of 2.0 μ m under 1050 ℃ temperature;
5) growth thickness is the n type Al of 0.1 μ m under 1050 ℃ temperature 0.1Ga 0.9The N:Si layer;
6) cool the temperature to 700 ℃ of growth In xGa yThe N/GaN multi-quantum pit structure, the thickness of InGaN trap layer is 3nm, the thickness that GaN builds layer is 8nm; The In component of InGaN trap layer is 0.1～0.3; The quantum well periodicity is 10;
7) at the p type GaN of 900 ℃ of growth thickness, 0.05 μ m layer;
8) at the p type AlGaN of 1000 ℃ of growth thickness, 0.05 μ m layer;
9) cool the temperature to 480 ℃, growing GaN resilient coating, buffer layer thickness are 20nm
10) prolong sheet and take out, and put into the AlGaInP based material special-purpose mocvd growth chamber of growing;
11) under atmosphere of hydrogen, with 700 ℃ Temperature Treatment epitaxial wafers 5 minutes, then at the GaP of 350 ℃ of growth thickness 20nm resilient coating;
12) rising reaction chamber temperature to 600 ℃, under atmosphere of hydrogen, heat treatment resilient coating 5 minutes makes the resilient coating recrystallization;
13) hole concentration of growth thickness 5.0 μ m is 6 * 10 under 600 ℃ temperature 18Cm -3The GaP:Mg layer.
This structure has adopted the GaN/GaP compound buffer layer, has further reduced the influence of lattice mismatch between GaN and the GaP, thereby obtains high-quality p type GaP layer, and (111) the face double crystal diffraction halfwidth that makes the GaP layer is less than 400 second of arcs.Adopt the compound limiting layer of p type GaN/AlGaN, electronics and hole in the more effective constraint quantum well of energy can be adjusted to the p-n junction of LED near the quantum well simultaneously.This structure is fit to make the blue-ray LED epitaxial wafer, can prolong the life-span of LED, and the luminous power of 450nm blue-ray LED is increased to more than 6.0 milliwatts by 3.0 milliwatts.
Embodiment 11
Structure such as Fig. 1 of the GaN base LED epitaxial wafer that this is novel show, is followed successively by substrate, low temperature buffer layer, not Doped GaN layer, n type GaN:Si layer, n type AlGaN:Si layer, quantum well, n type GaN limiting layer, resilient coating, p type GaP:Mg layer from bottom to up.
Its preparation method is:
1) adopts the special-purpose MOCVD of GaN, be warming up to 1000 ℃ and under atmosphere of hydrogen, toasted substrate 10 minutes;
2) be cooled to 480 ℃, growth thickness is the GaN low temperature resilient coating of 30nm on substrate;
3) be warming up to 1050 ℃, growth thickness is the not Doped GaN layer of 2.0 μ m;
4) growth thickness is the n type GaN:Si layer of 2.0 μ m under 1050 ℃ temperature;
5) cool the temperature to 700 ℃ of growth In xGa yThe N/GaN multi-quantum pit structure, the thickness of InGaN trap layer is 3nm, the thickness that GaN builds layer is 8nm; The In component of InGaN trap layer is 0.1～0.3; The quantum well periodicity is 10;
6) at 900 ℃ of growth thickness be the n type GaN layer of 0.02 μ m;
7) prolong sheet and take out, and put into the AlGaInP based material special-purpose mocvd growth chamber of growing;
8) under atmosphere of hydrogen, with 700 ℃ Temperature Treatment epitaxial wafers 5 minutes;
9) cool the temperature to 450 ℃, growth AlP resilient coating, buffer layer thickness is 20nm;
10) be cooled to the GaP resilient coating of 300 ℃ of growth thickness 20nm;
11) rising reaction chamber temperature to 650 ℃, under atmosphere of hydrogen, heat treatment resilient coating 5 minutes makes the resilient coating recrystallization;
12) hole concentration of growth thickness 4.0 μ m is 6 * 10 under 650 ℃ temperature 18Cm -3The GaP:Mg layer.
This structure has adopted the AlP/GaP compound buffer layer, has further reduced the influence of lattice mismatch between GaN and the GaP, thereby obtains high-quality p type GaP layer, and (111) the face double crystal diffraction halfwidth that makes the GaP layer prolongs the life-span of LED less than 360 second of arcs.

Claims (9)

1, a kind of GaN base LED epitaxial wafer, its structure are followed successively by substrate, n type layer, quantum well, limiting layer, resilient coating and p type layer from bottom to up, it is characterized in that the limiting layer of having grown between resilient coating and the quantum well, and p type layer is that hole concentration is 2 * 10 18～6 * 10 18Cm -3The GaP layer.
2, GaN base LED epitaxial wafer according to claim 1, it is characterized in that the limiting layer between quantum well and the resilient coating is a n type limiting layer, can be GaN layer or n type AlGaN layer or n type InGaN layer or the compound limiting layer of n type InGaN/GaN or the compound limiting layer of n type GaN/AlGaN, the thickness of limiting layer be 0.02 μ m～0.1 μ m.
3, GaN base LED epitaxial wafer according to claim 1, it is characterized in that the limiting layer between quantum well and the resilient coating is a p type limiting layer, can be GaN layer or p type AlGaN layer or p type InGaN layer or the compound limiting layer of p type InGaN/GaN or the compound limiting layer of p type GaN/AlGaN, the thickness of limiting layer be 0.02 μ m～0.2 μ m.
4, GaN base LED epitaxial wafer according to claim 1 is characterized in that the master that is subjected to of described p type GaP layer is Mg or Zn.
5, according to claim 1 or 4 described GaN base LED epitaxial wafers, the thickness that it is characterized in that described p type GaP layer is 0.2 μ m～10.0 μ m.
6, a kind of GaN base LED epitaxial wafer according to claim 1 is characterized in that described resilient coating is the GaP resilient coating, or the AlP resilient coating, or growing GaN/GaP compound buffer layer, or the AlP/GaP compound buffer layer.
7, GaN base LED epitaxial wafer according to claim 2 is characterized in that limiting layer is n type layer or a plain n type layer of mixing alms giver Si.
8, GaN base LED epitaxial wafer according to claim 3 is characterized in that limiting layer is to mix the p type layer that is subjected to main Mg.
9, a kind of preparation method of GaN base LED epitaxial wafer as claimed in claim 1 realizes by the MOCVD technology, it is characterized in that comprising the following steps:
1) adopts the AlGaInN based material special-purpose MOCVD that grows, growing n-type layer, quantum well structure successively on substrate;
2) at the n type limiting layer of 750 ℃～1100 ℃ growth thickness 0.02 μ m～0.1 μ m; Perhaps at the p type limiting layer of 750 ℃～1100 ℃ growth thickness 0.02 μ m～0.2 μ m;
3) epitaxial wafer is taken out, and put into the AlGaInP based material special-purpose mocvd growth chamber of growing;
4) atmosphere of hydrogen was handled substrate 2～10 minutes, the resilient coating of growing then for following 500 ℃～800 ℃;
5) growth thickness is that the hole concentration of 0.2 μ m～10.0 μ m is 2 * 10 under 500 ℃～700 ℃ temperature 18Cm -3～6 * 10 18Cm -3P type GaP layer.
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