CN108198913B - A kind of growing method of LED epitaxial slice - Google Patents

Abstract

The invention discloses a kind of growing methods of LED epitaxial slice, belong to technical field of semiconductors.It include: that a substrate is provided；Successively grown buffer layer, undoped gallium nitride layer, n type semiconductor layer, multiple quantum well layer and p type semiconductor layer over the substrate；Wherein, the buffer layer includes (n+1) a first gallium nitride layer and n the second gallium nitride layers of alternating growth, n >=2 and n is integer；The growth temperature of each second gallium nitride layer is higher than the growth temperature of respectively adjacent first gallium nitride layer, the growth rate of each second gallium nitride layer is faster than the growth rate of respectively adjacent first gallium nitride layer, and the thickness of each second gallium nitride layer is less than the thickness of respectively adjacent first gallium nitride layer.The present invention greatly improves the crystal quality of buffer layer entirety using higher compared with the second gallium nitride layer crystal quality of Seedling height temperature, reduces defect generation, improves the luminous efficiency and antistatic effect of light emitting diode.

Description

A method for growing light-emitting diode epitaxial wafers

technical field

The invention relates to the technical field of semiconductors, in particular to a method for growing a light-emitting diode epitaxial wafer.

Background technique

Light Emitting Diode (English: Light Emitting Diode, referred to as: LED) is a semiconductor electronic component that can emit light. It has the characteristics of high efficiency, environmental protection and green. technology field. The chip is the core component of the LED, including epitaxial wafers and electrodes arranged on the epitaxial wafers.

The existing LED epitaxial wafer includes a substrate and a buffer (English: buffer) layer stacked on the substrate in sequence, an undoped gallium nitride layer, an N-type semiconductor layer, and a multiple quantum well (English: Multiple Quantum Well, referred to as: MQW ) layer and P-type semiconductor layer. Wherein, the multi-quantum well layer includes multiple quantum wells and multiple quantum barriers, and the multiple quantum wells and multiple quantum barriers are alternately stacked. After the electrons provided by the N-type semiconductor layer and the holes provided by the P-type semiconductor layer are injected into the multi-quantum well layer, they are confined in the quantum well by the quantum barrier to perform radiative recombination and light emission.

The buffer layer is usually a gallium nitride layer grown at a low temperature of 500°C to 600°C to utilize low temperature for nucleation; while the undoped gallium nitride layer is a gallium nitride layer grown at a high temperature of 1000°C to 1100°C. On the basis of nucleation, high temperature is used to form crystals with better growth quality, which provides a good growth basis for N-type semiconductor layers, multi-quantum well layers and P-type semiconductor layers.

In the process of realizing the present invention, the inventor finds that there are at least the following problems in the prior art:

The crystal quality of the buffer layer grown at low temperature is very poor, and many defects will be generated, and these defects will continue to extend as the epitaxial wafer grows. Although high temperature is conducive to the formation of an undoped GaN layer with better crystal quality and avoids new defects in the undoped GaN layer, the undoped GaN layer does not play a role in the defects already generated in the buffer layer. Effective blocking effect, the defect will extend to the N-type semiconductor layer, the multi-quantum well layer and the P-type semiconductor layer, resulting in the occurrence of non-radiative recombination luminescence, which seriously affects the luminous efficiency and antistatic ability of the light-emitting diode.

SUMMARY OF THE INVENTION

In order to solve the problems in the prior art that seriously affect the luminous efficiency and antistatic ability of light emitting diodes, an embodiment of the present invention provides a method for growing epitaxial wafers of light emitting diodes. Described technical scheme is as follows:

An embodiment of the present invention provides a method for growing a light-emitting diode epitaxial wafer. The growth method includes:

providing a substrate;

sequentially growing a buffer layer, an undoped gallium nitride layer, an N-type semiconductor layer, a multi-quantum well layer and a P-type semiconductor layer on the substrate;

Wherein, the buffer layer includes (n+1) first gallium nitride layers and n second gallium nitride layers grown alternately, n≥2 and n is an integer; each second gallium nitride layer The growth temperature of each of the second gallium nitride layers is higher than the growth temperature of the respective adjacent first gallium nitride layers, and the growth rate of each of the second gallium nitride layers is faster than that of the respective adjacent first gallium nitride layers. rate, the thickness of each second GaN layer is smaller than the thickness of each adjacent first GaN layer.

Optionally, the growth temperature of each second gallium nitride layer is 20° C. to 60° C. higher than the growth temperature of each adjacent first gallium nitride layer.

Preferably, the growth temperature of each second gallium nitride layer increases layer by layer along the growth direction of the light emitting diode epitaxial wafer.

Preferably, the growth temperature of each first gallium nitride layer increases layer by layer along the growth direction of the light emitting diode epitaxial wafer.

Optionally, the growth rate of each of the second gallium nitride layers is 5 to 10 times that of the respective adjacent first gallium nitride layers.

Preferably, the growth rate of each second gallium nitride layer becomes faster layer by layer along the growth direction of the light emitting diode epitaxial wafer.

Preferably, the growth rate of each first gallium nitride layer becomes faster layer by layer along the growth direction of the light emitting diode epitaxial wafer.

Optionally, the total thickness of the n second gallium nitride layers is 1/6˜1/3 of the total thickness of the (n+1) first gallium nitride layers.

Preferably, the thickness of each second gallium nitride layer increases layer by layer along the growth direction of the light emitting diode epitaxial wafer.

Optionally, a portion of each of the first GaN layers adjacent to the second GaN layer is doped with aluminum.

The beneficial effects brought by the technical solution provided by the embodiments of the present invention are:

By inserting a second gallium nitride layer with a higher growth temperature into the first gallium nitride layer with a lower growth temperature to form a buffer layer, the crystal quality of the second gallium nitride layer with a higher growth temperature is higher, thereby greatly improving The overall crystal quality of the buffer layer reduces the generation of defects, and then reduces the defects extending to the N-type semiconductor layer, multi-quantum well layer and P-type semiconductor layer, avoids the occurrence of non-radiative recombination luminescence, and improves the luminous efficiency and antistatic of light-emitting diodes ability. Moreover, the growth rate of the second gallium nitride layer is faster and the thickness is smaller, which can reduce the influence of the higher growth temperature of the second gallium nitride layer on the first gallium nitride layer with a lower growth temperature, and avoid gallium nitride crystal growth. kind of decomposition. In addition, the second GaN layer is inserted in the first GaN layer, and the first GaN layer grows preferentially on the substrate, which is beneficial to the nucleation of GaN seeds at low temperature, while the second GaN layer Both the GaN layer and the first GaN layer are formed of GaN material, which is favorable for lattice matching with the undoped GaN layer.

Description of drawings

In order to illustrate the technical solutions in the embodiments of the present invention more clearly, the following briefly introduces the accompanying drawings used in the description of the embodiments. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can also be obtained from these drawings without creative effort.

FIG. 1 is a flow chart of a method for growing a light-emitting diode epitaxial wafer provided by Embodiment 1 of the present invention;

FIG. 2 is a schematic structural view of a light-emitting diode epitaxial wafer provided by Embodiment 1 of the present invention;

Fig. 3 is a schematic structural diagram of a buffer layer provided by Embodiment 1 of the present invention;

Fig. 3a is a schematic diagram of aluminum doping positions in the buffer layer provided by Embodiment 1 of the present invention;

Fig. 3b is a schematic diagram of the doping concentration of aluminum in the buffer layer provided by Embodiment 1 of the present invention;

4 is a flow chart of a method for growing a light-emitting diode epitaxial wafer provided by Embodiment 2 of the present invention;

Fig. 5 is a comparison diagram of the sample detection results provided by Example 2 of the present invention;

Figure 5a is a comparison chart of the sample detection results provided by Example 3 of the present invention;

Fig. 5b is a comparison chart of the test results of the samples provided in Example 4 of the present invention.

Detailed ways

In order to make the object, technical solution and advantages of the present invention clearer, the implementation manner of the present invention will be further described in detail below in conjunction with the accompanying drawings.

Example 1

An embodiment of the present invention provides a method for growing a light-emitting diode epitaxial wafer. FIG. 1 is a flow chart of the growth method provided in this embodiment. Referring to FIG. 1 , the growth method includes:

Step 101: Provide a substrate.

Step 102: growing a buffer layer, an undoped gallium nitride layer, an N-type semiconductor layer, a multi-quantum well layer and a P-type semiconductor layer sequentially on the substrate.

FIG. 2 is a schematic structural view of the formed light emitting diode epitaxial wafer. Wherein, 1 is a substrate, 2 is a buffer layer, 3 is an undoped gallium nitride layer, 4 is an N-type semiconductor layer, 5 is a multi-quantum well layer, and 6 is a P-type semiconductor layer. Referring to FIG. 2 , a buffer layer 2 , an undoped gallium nitride layer 3 , an N-type semiconductor layer 4 , a multi-quantum well layer 5 , and a P-type semiconductor layer 6 are sequentially stacked on a substrate 1 .

FIG. 3 is a schematic structural view of the buffer layer. Referring to FIG. 3, in this embodiment, the buffer layer 2 includes (n+1) first gallium nitride layers 21 and n second gallium nitride layers 22 grown alternately, n≥2 and n is an integer. The growth temperature of each second gallium nitride layer 22 is higher than the growth temperature of the respective adjacent first gallium nitride layers 21, and the growth rate of each second gallium nitride layer 22 is faster than that of the respective adjacent first gallium nitride layers. The growth rate of the gallium nitride layer 21 is such that the thickness of each second gallium nitride layer 22 is smaller than the thickness of each adjacent first gallium nitride layer 21 .

For example, the buffer layer 2 includes a first gallium nitride layer 21a, a second gallium nitride layer 22a, a first gallium nitride layer 21b, a second gallium nitride layer 22b and a first gallium nitride layer 21c grown in sequence, then The growth temperature of the first gallium nitride layer 21a is lower than the growth temperature of the second gallium nitride layer 22a, the growth rate of the first gallium nitride layer 21a is slower than the growth rate of the second gallium nitride layer 22a, the first gallium nitride layer The thickness of the gallium layer 21a is greater than the thickness of the second gallium nitride layer 22a; the growth temperature of the second gallium nitride layer 22a is higher than the growth temperature of the first gallium nitride layer 21b, and the growth rate of the second gallium nitride layer 22a is fast At the growth rate of the first gallium nitride layer 21b, the thickness of the second gallium nitride layer 22a is smaller than the thickness of the first gallium nitride layer 21b; the growth temperature of the first gallium nitride layer 21b is lower than that of the second gallium nitride layer The growth temperature of 22b, the growth rate of the first gallium nitride layer 21b is slower than the growth rate of the second gallium nitride layer 22b, the thickness of the first gallium nitride layer 21b is greater than the thickness of the second gallium nitride layer 22b; The growth temperature of the gallium nitride layer 22b is higher than the growth temperature of the first gallium nitride layer 21c, the growth rate of the second gallium nitride layer 22b is faster than the growth rate of the first gallium nitride layer 21c, the second gallium nitride layer The thickness of 22b is smaller than the thickness of the first gallium nitride layer 21c.

In the embodiment of the present invention, a second gallium nitride layer with a higher growth temperature is inserted into the first gallium nitride layer with a lower growth temperature to form a buffer layer, and the crystal quality of the second gallium nitride layer with a higher growth temperature is higher , so as to greatly improve the overall crystal quality of the buffer layer, reduce the generation of defects, and then reduce the defects extending to the N-type semiconductor layer, multi-quantum well layer and P-type semiconductor layer, avoid the occurrence of non-radiative recombination luminescence, and improve the luminescence of light-emitting diodes efficiency and antistatic capability. Moreover, the growth rate of the second gallium nitride layer is faster and the thickness is smaller, which can reduce the influence of the higher growth temperature of the second gallium nitride layer on the first gallium nitride layer with a lower growth temperature, and avoid gallium nitride crystal growth. kind of decomposition. In addition, the second GaN layer is inserted in the first GaN layer, and the first GaN layer grows preferentially on the substrate, which is beneficial to the nucleation of GaN seeds at low temperature, while the second GaN layer Both the GaN layer and the first GaN layer are formed of GaN material, which is favorable for lattice matching with the undoped GaN layer.

Optionally, n≤8. On the one hand, material waste and production cost increase are avoided, and on the other hand, too many second gallium nitride layers inserted at high temperature are prevented from affecting the generation and growth quality of gallium nitride seeds that need to be grown at low temperature.

Optionally, the portion of each first GaN layer adjacent to the second GaN layer can be doped with aluminum, so as to block the defects caused by the low-temperature growth of the first GaN layer along the growth of the light emitting diode. direction extension.

Still taking the example that the buffer layer 2 includes the first gallium nitride layer 21a, the second gallium nitride layer 22a, the first gallium nitride layer 21b, the second gallium nitride layer 22b and the first gallium nitride layer 21c grown in sequence , the part of the first gallium nitride layer 21a adjacent to the second gallium nitride layer 22a, the part of the first gallium nitride layer 21b adjacent to the second gallium nitride layer 22a, the first gallium nitride layer 21b and the second gallium nitride layer The parts adjacent to the gallium nitride layer 22b and the parts of the first gallium nitride layer 21c and the second gallium nitride layer 22b are all doped with aluminum (indicated by black in FIG. 3a).

Preferably, the doping concentration of aluminum in each first gallium nitride layer can be increased layer by layer along the growth direction of the light emitting diode epitaxial wafer, so as to block the defects caused by the low temperature growth of the first gallium nitride layer as much as possible along the light emitting diode layer. The growth direction of the diode extends.

Still taking the example that the buffer layer 2 includes the first gallium nitride layer 21a, the second gallium nitride layer 22a, the first gallium nitride layer 21b, the second gallium nitride layer 22b and the first gallium nitride layer 21c grown in sequence , as shown in FIG. 3b, the part of the first gallium nitride layer 21a adjacent to the second gallium nitride layer 22a, the part of the first gallium nitride layer 21b adjacent to the second gallium nitride layer 22a, the first nitrogen The doping concentration of aluminum in the portion of the gallium nitride layer 21b adjacent to the second gallium nitride layer 22b, and the portion of the first gallium nitride layer 21c adjacent to the second gallium nitride layer 22b increases gradually.

Specifically, the doping concentration of aluminum in each first gallium nitride layer may be 10 ²⁰ /cm ³ -10 ²¹ /cm ³ .

Still taking the example that the buffer layer 2 includes the first gallium nitride layer 21a, the second gallium nitride layer 22a, the first gallium nitride layer 21b, the second gallium nitride layer 22b and the first gallium nitride layer 21c grown in sequence , the doping concentration of aluminum in the part adjacent to the first gallium nitride layer 21a and the second gallium nitride layer 22a can be 2*10 ²⁰ /cm ³ , the first gallium nitride layer 21b and the second gallium nitride layer The doping concentration of aluminum in the part adjacent to 22a may be 4*10 ²⁰ /cm ³ , and the doping concentration of aluminum in the part adjacent to the first gallium nitride layer 21b and the second gallium nitride layer 22b may be 6* 10 ²⁰ /cm ³ , the doping concentration of aluminum in the portion adjacent to the first gallium nitride layer 21c and the second gallium nitride layer 22b may be 8*10 ²⁰ /cm ³ .

Optionally, the growth temperature of each second GaN layer may be 20° C.˜60° C. higher than the growth temperature of each adjacent first GaN layer. If the growth temperature of the second gallium nitride layer is lower than the growth temperature of the adjacent first gallium nitride layer by 20° C. or less, the growth temperature of the second gallium nitride layer may be too low to achieve the effect of improving the crystal quality. Effect; if the growth temperature of the second gallium nitride layer is higher than the growth temperature of the adjacent first gallium nitride layer by more than 60°C, it may be that the growth temperature of the second gallium nitride layer is too high to affect the gallium nitride crystal kind of damage.

Preferably, the growth temperature of each second gallium nitride layer may be 30° C.˜50° C. higher than the growth temperature of each adjacent first gallium nitride layer.

Further, the growth temperature of each second gallium nitride layer can be increased layer by layer along the growth direction of the light emitting diode epitaxial wafer. The initial growth temperature of the second gallium nitride layer is relatively low, which can avoid damage to the newly grown gallium nitride crystal seed as much as possible. As the subsequent gallium nitride seed crystals gradually stabilize, the growth temperature of the second gallium nitride layer gradually Layers are raised to maximize crystal quality.

Preferably, the difference between the growth temperatures of two adjacent second gallium nitride layers may be 5°C. Increasing the growth quality of the second gallium nitride layer layer by layer at intervals of 5°C can avoid damage to the low-temperature-grown gallium nitride seed crystals due to the rapid increase in the growth temperature while increasing the growth temperature to a certain extent. destroy.

Further, the growth temperature of each first gallium nitride layer can be increased layer by layer along the growth direction of the light emitting diode epitaxial wafer. With the gradual stabilization of the subsequent gallium nitride seed crystals, the growth temperature of the first gallium nitride layer is increased layer by layer, which can maximize the improvement of crystal quality.

Preferably, the difference between the growth temperatures of two adjacent first gallium nitride layers may be 3°C. Increasing the growth quality of the first gallium nitride layer layer by layer at intervals of 3°C can avoid damage to the low-temperature-grown gallium nitride seed crystals due to too fast growth temperature while increasing the growth temperature to a certain extent. destroy.

In practical application, the growth temperature of each second gallium nitride layer may be 600°C-625°C. For example, n=4, the growth temperatures of the four second GaN layers are 600°C, 605°C, 610°C and 615°C in sequence. Meanwhile, the growth temperature of each first gallium nitride layer may be 540° C.˜560° C. Still taking n=4 as an example, the growth temperatures of the five first gallium nitride layers are 540° C., 543° C., 546° C., 549° C. and 552° C. in sequence.

Optionally, the growth rate of each second gallium nitride layer may be 5 times to 10 times the average growth rate of each adjacent first gallium nitride layer. If the growth rate of the second GaN layer is less than 5 times the growth rate of the adjacent first GaN layer, the quality of the GaN seed may be affected due to the slow growth rate of the second GaN layer ; If the growth rate of the second gallium nitride layer is greater than 10 times the growth rate of the adjacent first gallium nitride layer, it may affect the gallium nitride crystal because the growth rate of the second gallium nitride layer is too fast The stability of species and crystal quality.

Preferably, the growth rate of each second gallium nitride layer may be 7 times to 8 times the average growth rate of each adjacent first gallium nitride layer.

Further, the growth rate of each second gallium nitride layer can be increased layer by layer along the growth direction of the light-emitting diode epitaxial wafer, so as to match the change of the growth temperature of each second gallium nitride layer, and avoid damaging the low-temperature growth In the case of GaN seed crystals, the crystal quality of the buffer layer should be as high as possible.

Specifically, the growth rate of each first gallium nitride layer can be increased layer by layer along the growth direction of the light-emitting diode epitaxial wafer, so as to match the change of the growth temperature of each first gallium nitride layer, and realize low-temperature nucleation In the case of , improve the crystal quality of the buffer layer as much as possible. At the same time, with the gradual stabilization of the subsequent gallium nitride seed crystals, the gradual increase in the growth rate of the first gallium nitride layer with poor crystal quality has a positive impact on the improvement of the overall crystal quality.

In practical application, the growth rate of each second gallium nitride layer may be 25nm/min˜50nm/min. For example, n=4, the growth rates of the four second gallium nitride layers are 25nm/min, 35nm/min, 40nm/min and 50nm/min in sequence. Meanwhile, the growth rate of each first gallium nitride layer may be 5nm/min˜10nm/min. Still taking n=4 as an example, the growth rates of the five first gallium nitride layers are 5 nm/min, 6 nm/min, 7 nm/min, 8 nm/min and 9 nm/min in sequence.

Optionally, the total thickness of the n second gallium nitride layers may be 1/6˜1/3 of the total thickness of the (n+1) first gallium nitride layers. If the total thickness of the n second gallium nitride layers is less than 1/6 of the total thickness of the (n+1) first gallium nitride layers, it may not be possible because the thickness of the second gallium nitride layers is too small. The effect of improving the crystal quality of the buffer layer may also affect the crystal quality of the buffer layer because the thickness of the first gallium nitride layer is too large; if the total thickness of n second gallium nitride layers is greater than (n+1) first 1/3 of the total thickness of the GaN layer, it may cause damage to the GaN seed due to the thickness of the second GaN layer being too large, or it may be caused by the thickness of the first GaN layer being too small. Base crystal failed.

Preferably, the total thickness of the n second gallium nitride layers may be 1/5˜1/4 of the total thickness of the (n+1) first gallium nitride layers.

Further, the thickness of each second gallium nitride layer may increase layer by layer along the growth direction of the light emitting diode epitaxial wafer. Since the thickness of the second gallium nitride layer has a great influence on its crystal quality improvement effect, with the gradual stabilization of the low-temperature gallium nitride seed crystal, the high-temperature-grown second gallium nitride layer has a great influence on the low-temperature The influence of the gallium seed crystal is getting smaller and smaller, increasing the thickness of the second gallium nitride layer layer by layer will not cause damage to the gallium nitride crystal seed crystal, and at the same time can maximize the crystal quality of the buffer layer.

In practical applications, the thickness of each second gallium nitride layer may be 0.2nm˜1nm. For example, n=4, and the thicknesses of the four second GaN layers are 0.2 nm, 0.4 nm, 0.8 nm and 1 nm in sequence. Meanwhile, the thickness of each first gallium nitride layer may be 2nm˜4nm. Still taking n=4 as an example, the thicknesses of the five first gallium nitride layers are 2nm, 2.5nm, 3nm, 3.5nm and 4nm in sequence.

In a specific implementation, the growth pressure of the buffer layer may be 200 torr-500 torr.

Specifically, the substrate may be a sapphire substrate, and the buffer layer is grown on the [0001] plane of the sapphire. The N-type semiconductor layer may be an N-type doped gallium nitride layer; the P-type semiconductor layer may be a P-type doped gallium nitride layer. The multi-quantum well layer may include multiple quantum wells and multiple quantum barriers, and multiple quantum wells and multiple quantum barriers are alternately stacked.

More specifically, the thickness of the undoped gallium nitride layer may be 2 μm˜3.5 μm. The thickness of the N-type semiconductor layer may be 2 μm˜3 μm. The thickness of the P-type semiconductor layer may be 50nm˜80nm. The thickness of each quantum well can be 2nm to 3nm; the thickness of each quantum barrier layer can be 8nm to 11nm; the number of quantum barriers is the same as the number of quantum wells, and the number of quantum wells can be 11 to 13; multiple quantum well layers The thickness can be 130nm-160nm.

In a specific implementation, the growth temperature of the undoped gallium nitride layer may be 1000°C-1100°C, the growth pressure may be 200torr-600torr, and the growth rate may be 2μm/h-5μm/h. The growth temperature of the N-type semiconductor layer may be 1000° C. to 1100° C., the growth pressure may be 200 torr to 300 torr, and the growth rate may be 3 μm/h to 8 μm/h. The growth temperature of the P-type semiconductor layer may be 940° C. to 980° C., the growth pressure may be 200 torr to 600 torr, and the growth rate may be 0.3 μm/h to 1 μm/h. The growth temperature of each quantum well can be 760°C-780°C, the growth pressure can be 200torr, the growth rate can be 0.2nm/min-0.6nm/min; the growth temperature of each quantum barrier layer can be 860°C-890°C, the growth The pressure can be 200 torr, and the growth rate can be 2nm/min˜5nm/min.

Optionally, the growth method may also include:

An electron blocking layer is grown between the multi-quantum well layer and the P-type semiconductor layer to prevent non-radiative recombination of electrons injected into the P-type semiconductor layer and holes.

Specifically, the electron blocking layer may be a P-type doped aluminum gallium nitride layer, specifically an _{AlyGa1 -yN} layer, where 0.15≤y≤0.25.

More specifically, the electron blocking layer may have a thickness of 30nm˜50nm.

In a specific implementation, the growth temperature of the electron blocking layer may be 930° C.˜970° C., the growth pressure may be 100 torr, and the growth rate may be 0.2 μm/h˜0.8 μm/h.

Optionally, before step 102, the growing method may also include:

Under a hydrogen atmosphere, the temperature is controlled to be 1000° C. to 1100° C., the pressure is 200 torr to 500 torr, and the substrate is processed for 5 minutes to 6 minutes to clean the surface of the substrate.

Optionally, the growth method may also include:

The surface of the P-type semiconductor layer is activated to form a P-type contact layer to form an ohmic contact between the epitaxial wafer and the transparent conductive layer in the chip.

It should be noted that the P-type semiconductor layer is usually doped with magnesium for P-type doping. Activating the P-type semiconductor layer mainly refers to activating the P-type magnesium doped in the semiconductor layer, so that more holes will be generated after the activation of magnesium to avoid Due to poor ohmic contact due to inactivation, the chip has high voltage and low brightness.

Specifically, activating the surface of the P-type semiconductor layer to form a P-type contact layer may include:

Under a nitrogen atmosphere, the temperature is controlled at 650° C. to 750° C., and the P-type semiconductor layer is processed for 20 minutes to 30 minutes.

Embodiment 2

An embodiment of the present invention provides a method for growing a light-emitting diode epitaxial wafer, and the growth method provided in this embodiment is a specific realization of the growth method provided in Embodiment 1. In this embodiment, Veeco K465i or C4 Metal Organic Chemical Vapor Deposition (English: Metal Organic Chemical Vapor Deposition, MOCVD for short) equipment is used to realize the growth of LED epitaxial wafers. Use high-purity hydrogen (H ₂ ) or high-purity nitrogen (N ₂ ) or a mixture of high-purity H ₂ and high-purity N ₂ as carrier gas, high-purity NH ₃ as nitrogen source, trimethylgallium (TMGa) and three Ethylgallium (TEGa) was used as gallium source, trimethylindium (TMIn) as indium source, trimethylaluminum (TMAl) as aluminum source, silane (SiH4) as N-type dopant, dimagnesocene (CP ₂ Mg ) as a P-type dopant. The pressure of the reaction chamber is controlled at 100torr～600torr.

Specifically, FIG. 4 is a flow chart of the growth method provided in this embodiment. Referring to FIG. 4, the growth method includes:

Step 301: Control the temperature of the reaction chamber to 1050° C. and the pressure to 250 torr, and perform high-temperature treatment on the sapphire substrate for 5.5 minutes in a hydrogen atmosphere.

Step 302: Control the pressure of the reaction chamber to 400 torr, and form a buffer layer on the sapphire substrate.

In this embodiment, the buffer layer includes 7 first GaN layers and 6 second GaN layers grown alternately. The thickness of the seven first gallium nitride layers is 3nm; the growth temperature of the seven first gallium nitride layers along the growth direction is 540°C, 543°C, 546°C, 549°C, 552°C, 555°C and 558°C ; The growth rates of the seven first gallium nitride layers along the growth direction are 5nm/min, 6nm/min, 7nm/min, 8nm/min, 9nm/min, 10nm/min and 11nm/min. The thicknesses of the six second GaN layers along the growth direction are 0.2nm, 0.4nm, 0.8nm, 1nm, 1.2nm and 1.5nm; the growth temperature of the six second GaN layers along the growth direction is 600°C , 605°C, 610°C, 615°C, 620°C and 625°C; the growth rates of the six second gallium nitride layers along the growth direction are 25nm/min, 30nm/min, 35nm/min, 40nm/min, 45nm/min min and 50nm/min.

Step 303: Control the temperature of the reaction chamber to 1050° C., the pressure to 400 torr, and the growth rate to 3.5 μm/h, and grow an undoped GaN layer with a thickness of 2.75 μm on the buffer layer.

Step 304: Control the temperature of the reaction chamber to 1050° C., the pressure to 250 torr, and the growth rate to 5.5 μm/h, and grow an N-type GaN layer with a thickness of 2.5 μm on the undoped GaN layer.

Step 305: Control the pressure of the reaction chamber to 200 torr, and grow the multi-quantum well layer on the N-type semiconductor layer.

In this embodiment, the multi-quantum well layer includes 12 quantum wells and 12 quantum barriers stacked alternately. Each quantum well layer is an indium gallium nitride layer with a thickness of 2.5nm, the growth temperature is 770°C, the growth pressure is 200torr, and the growth rate is 0.4nm/min; each quantum barrier layer is a gallium nitride layer, and the growth temperature is 875°C. The growth pressure is 200torr, the growth rate is 3.5nm/min, and the thickness is 12nm.

Step 306: Control the growth temperature to 950° C., the growth pressure to 150 torr, and the growth rate to 0.6 μm/h, and grow an AlGaN layer with a thickness of 40 nm on the MQW layer to form an electron blocking layer.

Step 307: Control the growth temperature to 960° C., the growth pressure to 400 torr, and the growth rate to 0.65 μm/h, and grow a P-type gallium nitride layer with a thickness of 65 nm on the electron blocking layer.

The first sample and the second sample are respectively plated with a 110nm indium tin oxide metal oxide (English: Indium Tin Oxides, abbreviated: ITO) layer, a 120nm Cr/Pt/Au electrode and a 40nm SiO ₂ protective layer, and the treated first sample and second sample were ground and cut into 305μm*635μm (12mi*25mil) core particles and 229μm*559μm (9mi*22mil) core particles. Wherein, the second sample is obtained by adopting the growth method of the light-emitting diode epitaxial wafer provided in this embodiment, and the growth method adopted by the first sample is basically the same as that of the second sample, except that the buffer layer in the first sample is A gallium nitride layer with a thickness of 22.5 nm was grown by controlling the temperature of the reaction chamber at 545° C., the pressure at 250 torr, and the growth rate at 15 nm/min.

Next, 300 crystal grains were selected at the same positions of the processed first sample and the second sample, and packaged into white LEDs under the same process conditions. The photoelectric properties of the crystal grains from the first sample and the crystal grains from the second sample were respectively tested by using an integrating sphere under the condition of a driving current of 120 mA.

Fig. 5 is the comparison chart of the result of above-mentioned test, referring to Fig. 5, test result shows, the crystal grain from the second sample is compared with the crystal grain from the first sample, and the light intensity all has under the driving current of 120mA It is obviously improved, and the antistatic ability is enhanced, indicating that the epitaxial wafer formed by the growth method provided in this embodiment can reduce defects and improve crystal quality.

Embodiment 3

An embodiment of the present invention provides a method for growing a light-emitting diode epitaxial wafer, and the growth method provided in this embodiment is another specific realization of the growth method provided in Embodiment 1. The growth method provided in this embodiment is basically the same as the growth method provided in Embodiment 2, except that the buffer layer includes 6 first gallium nitride layers and 5 second gallium nitride layers grown alternately. The thicknesses of the seven first gallium nitride layers are all 3 nm; the growth temperatures of the seven first gallium nitride layers are all 550° C.; the growth rates of the seven first gallium nitride layers are sequentially 8 nm/min along the growth direction. The thicknesses of the six second GaN layers along the growth direction are 0.2nm, 0.4nm, 0.8nm, 1nm, 1.2nm and 1.5nm; the growth temperature of the six second GaN layers along the growth direction is 600°C , 605°C, 610°C, 615°C, 620°C and 625°C; the growth rates of the six second gallium nitride layers along the growth direction are 25nm/min, 30nm/min, 35nm/min, 40nm/min, 45nm/min min and 50nm/min.

The light-emitting diode epitaxial wafer obtained in this embodiment was processed into the same sample as in Example 2 and tested. Figure 5a is a comparison chart of the results of the above tests. See Figure 5a. The test results show that the light intensity is equal to There is a significant improvement, and the antistatic ability is enhanced.

Embodiment 4

An embodiment of the present invention provides a method for growing a light-emitting diode epitaxial wafer, and the growth method provided in this embodiment is another specific realization of the growth method provided in Embodiment 1. The growth method provided in this embodiment is basically the same as the growth method provided in Embodiment 2, except that the buffer layer includes 7 first gallium nitride layers and 6 second gallium nitride layers grown alternately. The thickness of the seven first gallium nitride layers is 3nm; the growth temperature of the seven first gallium nitride layers along the growth direction is 540°C, 543°C, 546°C, 549°C, 552°C, 555°C and 558°C ; The growth rates of the seven first gallium nitride layers along the growth direction are 5nm/min, 6nm/min, 7nm/min, 8nm/min, 9nm/min, 10nm/min and 11nm/min. The thicknesses of the six second GaN layers along the growth direction are 0.2nm, 0.4nm, 0.8nm, 1nm, 1.2nm and 1.5nm; the growth temperature of the six second GaN layers along the growth direction is 610°C ; The growth rate of the six second gallium nitride layers along the growth direction is 35nm/min.

The light-emitting diode epitaxial wafer obtained in this embodiment was processed into the same sample as in Example 2 and tested. Figure 5b is a comparison chart of the results of the above tests. See Figure 5b. The test results show that the light intensity is equal to There is a significant improvement, and the antistatic ability is enhanced.

It should be noted that in other embodiments, parameters such as the growth temperature of each layer may also take other values, and the present invention is not limited to the values in the above embodiments.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included in the protection of the present invention. within range.

Claims (10)

1. A growth method of light-emitting diode epitaxial wafer, it is characterized in that, described growth method comprises: providing a substrate; sequentially growing a buffer layer, an undoped gallium nitride layer, an N-type semiconductor layer, a multi-quantum well layer and a P-type semiconductor layer on the substrate; Wherein, the buffer layer includes (n+1) first gallium nitride layers and n second gallium nitride layers grown alternately, n≥2 and n is an integer; each second gallium nitride layer The growth temperature of each of the second gallium nitride layers is higher than the growth temperature of the respective adjacent first gallium nitride layers, and the growth rate of each of the second gallium nitride layers is faster than that of the respective adjacent first gallium nitride layers. rate, the thickness of each second GaN layer is smaller than the thickness of each adjacent first GaN layer. 2. The growth method according to claim 1, characterized in that the growth temperature of each second gallium nitride layer is 20° C. to 60° C. higher than the growth temperature of the respective adjacent first gallium nitride layers. ℃. 3 . The growth method according to claim 2 , wherein the growth temperature of each second gallium nitride layer increases layer by layer along the growth direction of the light emitting diode epitaxial wafer. 4 . 4 . The growth method according to claim 2 , wherein the growth temperature of each first gallium nitride layer increases layer by layer along the growth direction of the light emitting diode epitaxial wafer. 5. The growth method according to any one of claims 1 to 4, characterized in that, the growth rate of each of the second GaN layers is equal to the growth rate of the respective adjacent first GaN layers. 5 times to 10 times. 6 . The growth method according to claim 5 , wherein the growth rate of each second gallium nitride layer becomes faster layer by layer along the growth direction of the light emitting diode epitaxial wafer. 7. The growth method according to claim 5, wherein the growth rate of each of the first GaN layers becomes faster layer by layer along the growth direction of the light emitting diode epitaxial wafer. 8. The growth method according to any one of claims 1 to 4, characterized in that, the total thickness of the n second gallium nitride layers is equal to that of the (n+1) first gallium nitride layers 1/6~1/3 of the total thickness. 9 . The growth method according to claim 8 , wherein the thickness of each second gallium nitride layer increases layer by layer along the growth direction of the light emitting diode epitaxial wafer. 10 . The growth method according to claim 1 , wherein a part of each first gallium nitride layer adjacent to the second gallium nitride layer is doped with aluminum. 11 .