Growth method of GaN-based epitaxial layer for improving anti-static capability of LED chip after aging

Abstract

The application relates to the field of semiconductor electronic technology, in particular to a GaN-based epitaxial layer growth method for improving the anti-static capability of an LED chip after aging. The growth method comprises the following steps: placing an AlN substrate into a reaction cavity; sequentially growing a buffer layer, a U-shaped GaN layer, an N-type GaN layer, a multi-quantum well active region layer, a low-temperature P-type GaN layer, a p-type AlGaN superlattice layer and a high-temperature P-type GaN layer; and growing a current expansion layer with a thickness of 5-10 nm on the high-temperature P-type GaN layer to obtain a GaN-based epitaxial layer; and the P-InGaN / MgN / GaN superlattice current expansion layer prepared by the method can improve the P-type epitaxial quality of the epitaxial layer and improve the anti-static capability of the large-current expansion and the aged LED.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of semiconductor electronics, in particular to a GaN-based epitaxial layer growth method for improving the anti-static ability of an LED chip after aging. BACKGROUND

[0002] GaN (gallium nitride) based light emitting diodes (LEDs) as a new type of high efficiency, environmentally friendly, green solid-state lighting source, with low voltage, low power consumption, small size, light weight, long life, high reliability and other advantages, is being rapidly and widely used in traffic signal lights, mobile phone backlights, outdoor full-color display screens, urban landscape lighting, car interior and exterior lights, tunnel lights and other fields. Therefore, how to improve the performance of LEDs in all aspects is focused by the industry.

[0003] In the preparation of GaN-based LED epitaxial layers, the characteristics of the provided holes (P-type) are an important factor affecting the electrical properties of the LED, especially the anti-static ability of the LED. At present, the P layer growth for providing holes is involved in the growth of LED epitaxial layers by MOCVD (metal-organic chemical vapor deposition) in China. Generally, it is composed of low-temperature grown P-type GaN and high-temperature grown P-type AlGaN / GaN p-type AlGaN superlattice layers. The Chinese invention patent with publication number CN105161582A discloses a method for preparing a deep ultraviolet LED using MOCVD technology. The LED epitaxial structure from bottom to top in order is: patterned sapphire substrate, low-temperature AlN nucleation layer, high-temperature AlN layer, multi-period AlGaN / AlN superlattice stress regulation layer; n-AlInGaN contact layer, n-AlGaN current expansion layer, asymmetric single quantum well active region, p-AlGaN electron blocking layer, p-AlGaN limiting layer and p-GaN contact layer, which can effectively reduce the Droop effect of the LED chip under high current density, improve the injection efficiency of the carriers, and improve the luminous efficiency of the device, but at the same time, it also increases the leakage channel, resulting in an increase in the energy consumption of the device, and also causes the anti-static ability to decline after aging. SUMMARY

[0004] In order to overcome the defects of the above-mentioned prior art, the technical problem to be solved by the present application is to provide a GaN-based epitaxial layer growth method for improving the anti-static ability of an LED chip after aging.

[0005] In order to solve the above technical problems, the technical scheme adopted by the present application is as follows: a GaN-based epitaxial layer growth method for improving the anti-static ability of an LED chip after aging, comprising the following steps:

[0006] S1: growing buffer layer, U-shaped GaN layer, N-type GaN layer, multi-quantum well active region layer, low-temperature P-type GaN layer, p-type AlGaN superlattice layer and high-temperature P-type GaN layer on the AlN substrate in sequence;

[0007] S2: growing a current spreading layer with a thickness of 5-10 nm on the high-temperature P-type GaN layer to obtain a GaN-based epitaxial layer;

[0008] The current spreading layer is a P-InGaN / MgN / GaN superlattice, the period of the P-InGaN / MgN / P-GaN superlattice is 5-10, the thickness of a single period of the P-InGaN / MgN / P-GaN superlattice is 1-2 nm, and the thickness ratio of P-InGaN / MgN / P-GaN in a single period is 2:1:1.

[0009] The GaN-based epitaxial layer provided by the method for improving the anti-static ability of LED after aging has the P-InGaN / MgN / GaN superlattice current spreading layer, which improves the P-type epitaxial quality of the epitaxial layer, improves the large current spreading and the anti-static ability of LED after aging, and the GaN-based epitaxial layer of the application improves the mechanical mode 300V after ESD (static discharge) aging compared with the conventional LED structure. BRIEF DESCRIPTION OF DRAWINGS

[0010] Figure 1 Fig. 1 is a structural schematic diagram of a GaN-based epitaxial layer of the embodiment of the application;

[0011] Label explanation: 1, AlN substrate; 2, buffer layer; 3, U-shaped GaN layer; 4, N-type GaN layer; 5, multi-quantum well active region layer; 6, low-temperature P-type GaN layer; 7, p-type AlGaN superlattice layer; 8, high-temperature P-type GaN layer, 9, current spreading layer. DETAILED DESCRIPTION

[0012] To explain the technical content, the purposes and effects of the application in detail, the following will be described in combination with the embodiments and the drawings.

[0013] The most key idea of the application is to prepare the P-InGaN / MgN / GaN superlattice current spreading layer, which improves the P-type epitaxial quality of the epitaxial layer and improves the large current spreading and the anti-static ability of LED after aging.

[0014] Please refer to Figure 1 Fig. 1, the method for improving the anti-static ability of LED chip after aging provided by the application, includes the following steps:

[0015] S1: sequentially growing a buffer layer, a U-shaped GaN layer, an N-type GaN layer, a multi-quantum well active region layer, a low-temperature P-type GaN layer, a p-type AlGaN superlattice layer and a high-temperature P-type GaN layer on an AlN substrate;

[0016] S2: growing a current spreading layer with a thickness of 5-10 nm on the high-temperature P-type GaN layer to obtain a GaN-based epitaxial layer;

[0017] The current spreading layer is a P-InGaN / MgN / GaN superlattice.

[0018] As can be seen from the above description, the GaN-based epitaxial layer growth method for improving the anti-static ability of an LED after aging provided by the application prepares a P-InGaN / MgN / GaN superlattice current spreading layer, the superlattice current spreading layer is doped with In / Mg, the In atoms act as activators to increase the incorporation amount of Mg atoms, can form a good ohmic contact with the chip electrode, reduce the voltage drop, improve the heat generation during the aging test, the MgN / GaN structure forms a GaN layer through the diffusion of Mg atoms, which can improve the surface morphology of the P layer and reduce the leakage channel, and the band gap difference of the MgN / GaN layer can also improve the current spreading, the structure improves the P-type epitaxial quality of the epitaxial layer, improves the large current spreading and the anti-static ability of the LED after aging, and the GaN-based epitaxial layer of the application improves the mechanical mode 300V after ESD (electrostatic discharge) aging compared with the conventional LED structure.

[0019] Further, the period of the P-InGaN / MgN / P-GaN superlattice is 5-10, the thickness of a single period of the P-InGaN / MgN / P-GaN superlattice is 1-2 nm, and the thickness ratio of P-InGaN / MgN / P-GaN in a single period is 2:1:1.

[0020] As can be seen from the above description, too many or too thick periods and period thicknesses will affect the light extraction rate, and too thin or too few cannot improve the current spreading.

[0021] Further, the doping concentration of Mg in the current spreading layer is 1E+18-5E+19 atom / cm 3 , and the doping concentration of In is 1E+19-2E+20 atom / cm 3 .

[0022] Further, the growth of the current spreading layer is carried out in a reaction chamber, the temperature of the reaction chamber is 700-800 DEG C, the pressure is 500-1000 mbar, 60000-75000 sccm of NH3, 25-50 sccm of TEGa and 300-1000 sccm of Cp2Mg are introduced, and 100-500 sccm of TMIn is intermittently introduced.

[0023] Furthermore, the intermittency during the growth of the current-extended layer refers to the following: during the growth of P-InGaN / MgN / P-GaN, only the P-InGaN layer is conditioned on TMIn, TEGa and Cp2Mg; during the growth of the MgN layer, only Mg is conditioned on; and during the growth of P-GaN, TEGa and Cp2Mg are conditioned on.

[0024] As can be seen from the above description, temperature and pressure need to be adjusted in conjunction with the doping concentration. At a lower temperature, more IN is doped under the same IN flow rate. At a higher pressure, the growth rate is faster, but the amount of IN doped decreases.

[0025] Furthermore, the growth of the buffer layer is carried out in a reaction chamber at a temperature of 780–880°C and a pressure of 100–200 mbar. Ammonia, nitrogen, and 100–300 sccm of TMGa2 are introduced for 1–2 minutes to obtain a buffer layer with a thickness of 0.005–0.1 μm.

[0026] As can be seen from the above description, the type and pressure of the gas will change the V / III molar ratio, thereby affecting the growth rate.

[0027] Furthermore, the growth of the U-shaped GaN layer is carried out in a reaction chamber at a temperature of 1100–1300 °C and a pressure of 250–350 mbar, with nitrogen, hydrogen, ammonia, and TMGa2 introduced; the process is continued for 10–14 min to obtain the U-shaped GaN layer.

[0028] Furthermore, the growth of the N-type GaN layer is carried out in a reaction chamber at a temperature of 1000–1100 °C and a pressure of 500–1000 mbar, resulting in an N-type GaN layer with a thickness of 2–3 μm.

[0029] Furthermore, the growth of the multi-quantum-well active region layer is carried out in a reaction chamber at a temperature of 700–800 °C and a pressure of 500–1000 mbar. While ammonia, nitrogen and 50–400 sccm of TEGa are introduced, 1200–1500 sccm of TMIn are intermittently introduced to grow periodic InGaN / GaN multi-quantum-well active regions.

[0030] The InGaN / GaN has a period number of 10–16; the thickness of the multi-quantum-well active region layer is 0.15–0.2 μm, and the In doping concentration is 1E+20–2E+20 atom / cm. 3 .

[0031] Furthermore, the intermittency during the growth of multiple quantum wells is specifically as follows: during the growth of InGaN / GaN, only the InGaN layer is open to both TMI and TEGa, while during the growth of GaN, only TEGa is open.

[0032] Further, the low-temperature P-type GaN layer is grown in a reaction cavity with a temperature of 600-700 DEG C and a pressure of 300-800 mbar, and 55000-65000 sccm of NH3 and 25-50 sccm of TMGa2 are introduced to obtain a low-temperature P-type GaN layer with a thickness of 60-90 nm.

[0033] Further, the p-type AlGaN superlattice layer is grown in a reaction cavity with a temperature of 700-950 DEG C and a pressure of 300-800 mbar, and 30000-60000 sccm of NH3, 30-50 sccm of TMGa2, 1500-2000 sccm of Cp2Mg and 150-200 sccm of TMAl are introduced to grow a periodic p-type AlGaN superlattice layer of AlGaN / GaN;

[0034] The period of AlGaN / GaN is 5-10, the monolayer thickness of AlGaN is 4-6 nm, and the thickness ratio of AlGaN and GaN layers in a single period is 1:1-3:1; the thickness of the p-type AlGaN superlattice layer is 50-70 nm, the doping concentration of Mg is 1E+18-1E+19 atom / cm 3 , and the doping concentration of Al is 1E+17-1E+18 atom / cm 3 .

[0035] Further, the high-temperature P-type GaN layer is grown in a reaction cavity with a temperature of 900-1050 DEG C and a pressure of 600-1000 mbar, and 60000-75000 sccm of NH3, 25-50 sccm of TMGa2 and 2000-3000 sccm of Cp2Mg are introduced to obtain a high-temperature P-type GaN layer with a thickness of 60-90 nm; the doping concentration of Mg in the high-temperature P-type GaN layer is 1E+20-3E+20 atom / cm 3 .

[0036] As can be seen from the above description, the high-Al-component p-type AlGaN electron blocking layer blocks the overflow of electrons, but as the Al component rises, the ionization energy of Mg rapidly increases and the crystal quality significantly decreases, resulting in a sharp decrease in hole ionization efficiency and concentration, which in turn causes a decrease in hole injection efficiency, reduces the light-emitting efficiency, and further exacerbates the efficiency drop effect, aging and light decay under the condition of large current injection. The GaN-based epitaxial layer growth method of the application grows a low-temperature P-type GaN layer, a p-type AlGaN superlattice layer and a high-temperature P-type GaN layer on the multi-quantum well active region layer in sequence, and the Al component content is low, thereby being conducive to the Droop effect of the LED chip under a large current density, improving the injection efficiency of the carriers and improving the light-emitting efficiency of the device.

[0037] Please refer to Figure 1 As shown, Embodiment 1 of the present invention is: a method for growing a GaN-based epitaxial layer to improve the antistatic capability of LED chips after aging, comprising the following steps:

[0038] S1: Place the AlN substrate 1 into the reaction chamber of the metal-organic chemical vapor deposition equipment;

[0039] S2: Set the temperature of the reaction chamber to 880℃ and the pressure to 200mbar, and introduce ammonia, nitrogen and 300sccm of TMGa2 for 1.5min to form a buffer layer 2 with a thickness of 0.1um;

[0040] S3: Set the temperature of the reaction chamber to 1300℃ and the pressure to 350mbar, and introduce nitrogen, hydrogen, ammonia and TMGa2; continue for 14 minutes to form a U-shaped GaN layer 3 on the buffer layer 2.

[0041] S4: Set the temperature of the reaction chamber to 1100℃ and the pressure to 1000mbar, and form an N-type GaN layer 4 with a thickness of 3um on the U-type GaN layer 3;

[0042] S5: Set the reaction chamber temperature to 800℃ and the pressure to 1000mbar. While introducing ammonia, nitrogen, and 400sccm of TEGa, intermittently introduce 1500sccm of TMIn (during the InGaN / GaN growth cycle, only the InGaN layer is conditioned with both TMIn and TEGa; during the GaN layer growth, only TEGa is conditioned with TEGa). This results in the growth of a periodic InGaN / GaN multi-quantum-well active region layer 5; the InGaN / GaN cycle number is 16; the thickness of the multi-quantum-well active region layer 5 is 0.2µm, and the In doping concentration is 2E+20 atom / cm. 3 .

[0043] S6: Set the temperature of the reaction chamber to 700℃ and the pressure to 800mbar, introduce 65000sccm of NH3 and 50sccm of TMGa2, and form a low-temperature P-type GaN layer 6 with a thickness of 90nm on the multi-quantum-well active region layer 5.

[0044] S7: Set the reaction chamber temperature to 950℃ and pressure to 800mbar. Introduce 60000 sccm of NH3, 50 sccm of TMGa2, 2000 sccm of Cp2Mg, and 200 sccm of TMAl to form a periodic AlGaN / GaN p-type AlGaN superlattice layer 7 on the low-temperature p-type GaN layer 6. The AlGaN / GaN period is 10, the AlGaN monolayer thickness is 6nm, and the thickness ratio of AlGaN to GaN layers in a single period is 3:1. The p-type AlGaN superlattice layer 7 has a thickness of 70nm, and the Mg doping concentration is 1E+19 atom / cm. 3 The Al doping concentration is 1E+18 atoms / cm³. 3 .

[0045] S8: The reaction chamber temperature is set to 1050℃ and the pressure to 1000mbar. 75000 sccm of NH3, 50 sccm of TMGa2, and 3000 sccm of Cp2Mg are introduced to form a 90nm thick high-temperature p-type GaN layer 8 on the p-type AlGaN superlattice layer 7. The Mg doping concentration in the high-temperature p-type GaN layer 8 is 3E+20 atom / cm³. 3 .

[0046] S9: Set the temperature of the reaction chamber to 800℃ and the pressure to 500mbar. Introduce 75000sccm of NH3, 50sccm of TEGa, and 1000sccm of Cp2Mg. Intermittently introduce 500sccm of TMIn (during the growth of P-InGaN / MgN / P-GaN, only the P-InGaN layer is infused with TMIn, while TEGa and Cp2Mg are introduced; during the growth of the MgN layer, only Mg is introduced; and during the growth of P-GaN, TEGa and Cp2Mg are introduced). A current-spreading layer 9 with a thickness of 5-10nm is formed on the basis of the high-temperature P-type GaN layer 8, thus obtaining a GaN-based epitaxial layer.

[0047] The current spreading layer 9 is a P-InGaN / MgN / GaN superlattice with 10 periods. The thickness of a single period of the P-InGaN / MgN / P-GaN superlattice is 2 nm, and the thickness ratio of P-InGaN / MgN / P-GaN in a single period is 2:1:1. The doping concentration of Mg in the current spreading layer is 5E+19 atoms / cm². 3 The doping concentration of In is 2E+20 atoms / cm. 3 .

[0048] Embodiment 2 of the present invention is: a method for growing a GaN-based epitaxial layer to improve the antistatic capability of LED chips after aging, comprising the following steps:

[0049] S1: Place the AlN substrate 1 into the reaction chamber of the metal-organic chemical vapor deposition equipment;

[0050] S2: Set the temperature of the reaction chamber to 780℃ and the pressure to 100mbar, and introduce ammonia, nitrogen and 100-300sccm of TMGa2 for 1.5min to form a buffer layer 2 with a thickness of 0.005um;

[0051] S3: Set the temperature of the reaction chamber to 1100℃ and the pressure to 250mbar, and introduce nitrogen, hydrogen, ammonia and TMGa2; continue for 12 minutes to form a U-shaped GaN layer 3 on the buffer layer 2.

[0052] S4: Set the temperature of the reaction chamber to 1000℃ and the pressure to 500mbar, and form an N-type GaN layer 4 with a thickness of 2um on the U-type GaN layer 3;

[0053] S5: Set the reaction chamber temperature to 700℃ and pressure to 500mbar. While introducing ammonia, nitrogen, and 50sccm of TEGa, intermittently introduce 1200sccm of TMIn (during the InGaN / GaN growth cycle, only the InGaN layer is conditioned with both TMI and TEGa; during the GaN layer growth, only TEGa is conditioned with TEGa). This grows a periodic InGaN / GaN multi-quantum-well active region layer 5; the InGaN / GaN cycle number is 10; the thickness of the multi-quantum-well active region layer 5 is 0.15–0.2µm, and the In doping concentration is 1E+20–2E+20 atom / cm. 3 .

[0054] S6: Set the temperature of the reaction chamber to 600℃ and the pressure to 300~800mbar, introduce 55000sccm of NH3 and 25sccm of TMGa2, and form a low-temperature P-type GaN layer 6 with a thickness of 60nm on the multi-quantum-well active region layer 5.

[0055] S7: Set the temperature of the reaction chamber to 700℃ and the pressure to 300mbar. Introduce 30000 sccm of NH3, 30 sccm of TMGa2, 1500 sccm of Cp2Mg, and 150 sccm of TMAl to form a periodic AlGaN / GaN p-type AlGaN superlattice layer 7 on the low-temperature p-type GaN layer 6. The AlGaN / GaN period is 5, the AlGaN monolayer thickness is 4nm, and the thickness ratio of AlGaN to GaN layers in a single period is 1:1. The p-type AlGaN superlattice layer 7 is 50nm thick, and the Mg doping concentration is 1E+18 atom / cm. 3 The Al doping concentration is 1E+17 atom / cm³. 3.

[0056] S8: The reaction chamber temperature is set to 900℃ and the pressure to 600mbar. NH3 at 60000 sccm, TMGa2 at 25 sccm, and Cp2Mg at 2000 sccm are introduced to form a high-temperature p-type GaN layer 8 with a thickness of 60–90 nm on the p-type AlGaN superlattice layer 7. The Mg doping concentration in the high-temperature p-type GaN layer 8 is 1E+20 atom / cm³. 3 .

[0057] S9: Set the temperature of the reaction chamber to 800℃ and the pressure to 1000mbar. Introduce 60000 sccm of NH3, 25 sccm of TEGa, and 300 sccm of Cp2Mg. Intermittently introduce 100 sccm of TMIn (during the growth of P-InGaN / MgN / P-GaN, only the P-InGaN layer is infused with TMIn, while TEGa and Cp2Mg are introduced; during the growth of the MgN layer, only Mg is introduced; and during the growth of P-GaN, TEGa and Cp2Mg are introduced). A current-spreading layer 9 with a thickness of 5nm is formed on the basis of the high-temperature P-type GaN layer 8, thus obtaining the GaN-based epitaxial layer.

[0058] The current spreading layer 9 is a P-InGaN / MgN / GaN superlattice with 5 periods. The thickness of a single period of the P-InGaN / MgN / P-GaN superlattice is 1 nm, and the thickness ratio of P-InGaN / MgN / P-GaN in a single period is 2:1:1. The Mg doping concentration in the current spreading layer is 1E+18 atom / cm. 3 The doping concentration of In is 1E+19 atoms / cm. 3 .

[0059] Embodiment 3 of the present invention is: a method for growing a GaN-based epitaxial layer to improve the antistatic capability of LED chips after aging, comprising the following steps:

[0060] S1: Place the AlN substrate 1 into the reaction chamber of the metal-organic chemical vapor deposition equipment;

[0061] S2: Set the temperature of the reaction chamber to 800℃ and the pressure to 150mbar, and introduce ammonia, nitrogen and 200sccm of TMGa2 for 1.5min to form a buffer layer 2 with a thickness of 0.05um;

[0062] S3: Set the temperature of the reaction chamber to 1200℃ and the pressure to 300mbar, and introduce nitrogen, hydrogen, ammonia and TMGa2; continue for 10 minutes to form a U-shaped GaN layer 3 on the buffer layer 2.

[0063] S4: Set the temperature of the reaction chamber to 1050℃ and the pressure to 750mbar, and form an N-type GaN layer 4 with a thickness of 2.5um on the U-type GaN layer 3;

[0064] S5: Set the reaction chamber temperature to 800℃ and the pressure to 1000mbar. While introducing ammonia, nitrogen, and 200sccm of TEGa, intermittently introduce 1350sccm of TMIn (during the InGaN / GaN growth cycle, only the InGaN layer is conditioned with both TMI and TEGa; during the GaN layer growth, only TEGa is conditioned with TEGa). This results in the growth of a periodic InGaN / GaN multi-quantum-well active region layer 5; the InGaN / GaN cycle number is 13; the thickness of the multi-quantum-well active region layer 5 is 0.17µm, and the In doping concentration is 1.5E+20 atom / cm. 3 .

[0065] S6: Set the temperature of the reaction chamber to 650℃ and the pressure to 500mbar, introduce 60000sccm of NH3 and 45sccm of TMGa2, and form a low-temperature P-type GaN layer 6 with a thickness of 70nm on the multi-quantum-well active region layer 5.

[0066] S7: Set the temperature of the reaction chamber to 825℃ and the pressure to 550mbar. Introduce 45000 sccm of NH3, 40 sccm of TMGa2, 1800 sccm of Cp2Mg, and 170 sccm of TMAl to form a periodic AlGaN / GaN p-type AlGaN superlattice layer 7 on the low-temperature p-type GaN layer 6. The AlGaN / GaN period is 8, the AlGaN monolayer thickness is 5nm, and the thickness ratio of AlGaN to GaN layers in a single period is 2:1. The p-type AlGaN superlattice layer 7 has a thickness of 60nm, and the Mg doping concentration is 1E+18 atom / cm. 3 The Al doping concentration is 1E+17 atom / cm³. 3 .

[0067] S8: The reaction chamber temperature is set to 975℃ and the pressure to 800mbar. 70000 sccm of NH3, 30 sccm of TMGa2, and 2500 sccm of Cp2Mg are introduced to form a 70nm thick high-temperature p-type GaN layer 8 on the p-type AlGaN superlattice layer 7. The Mg doping concentration in the high-temperature p-type GaN layer 8 is 2E+20atom / cm³. 3 .

[0068] S9: Set the temperature of the reaction chamber to 700℃ and the pressure to 750mbar. Introduce 70000sccm of NH3, 30sccm of TEGa, and 600sccm of Cp2Mg. Intermittently introduce 300sccm of TMIn (during the growth of P-InGaN / MgN / P-GaN, only the P-InGaN layer is infused with TMIn, while TEGa and Cp2Mg are introduced; during the growth of the MgN layer, only Mg is introduced; and during the growth of P-GaN, TEGa and Cp2Mg are introduced). A current-spreading layer 9 with a thickness of 7nm is formed on the basis of the high-temperature P-type GaN layer 8, thus obtaining the GaN-based epitaxial layer.

[0069] The current spreading layer 9 is a P-InGaN / MgN / GaN superlattice with 7 periods. The thickness of a single period of the P-InGaN / MgN / P-GaN superlattice is 1.5 nm, and the thickness ratio of P-InGaN / MgN / P-GaN in a single period is 2:1:1. The Mg doping concentration in the current spreading layer is 1E+19 atom / cm. 3 The doping concentration of In is 1E+19 atoms / cm. 3 .

[0070] Embodiment four of the present invention is as follows:

[0071] The difference between Example 4 and Example 2 is: S9: The temperature of the reaction chamber is set to 750°C and the pressure to 1000 mbar.

[0072] Comparative Example 1 of the present invention is:

[0073] The difference between Comparative Example 1 and Example 1 is that no current spreading layer was prepared (no S9).

[0074] LED chips were prepared using GaN-based epitaxial layers from Examples 1-4 and Comparative Example 1 (specific steps: epitaxial wafer cleaning -> MESA -> CBL -> ITO -> MET -> PV -> electro-alloying -> COW testing -> grinding and thinning -> scratching -> sorting and full testing). The LED chips were made into 6*11mil blue light cores. They were powered on for one week at room temperature using a current of 50mA (more than twice the normal operating current of 20mA), and then removed from the rack for ESD testing in mechanical mode. The test results are shown in Table 1.

[0075] Table 1

[0076]

[0077] In summary, the GaN-based epitaxial layer growth method for improving the anti-static capability of LEDs after aging provided by this invention prepares a P-InGaN / MgN / GaN superlattice current spreading layer. This superlattice current spreading layer, through In / Mg doping, allows In atoms to act as activators, increasing the incorporation of Mg atoms and forming good ohmic contact with the chip electrodes, reducing voltage drop and improving heat generation during aging tests. The MgN / GaN structure, through the diffusion of Mg atoms to form a GaN layer, improves the surface morphology of the P layer and reduces defect channels. Simultaneously, the band difference of the MgN / GaN layer also improves current spreading. This structure improves the P-type epitaxial quality of the epitaxial layer, enhances high current spreading and the anti-static capability of the LED after aging. Compared with conventional LED structures, the GaN-based epitaxial layer of this invention improves the mechanical mode ESD by 300V after aging.

[0078] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent modifications made based on the content of the present invention specification and drawings, or direct or indirect applications in related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A method for growing a GaN-based epitaxial layer to improve the antistatic capability of LED chips after aging, characterized in that, The method comprises the following steps: S1: sequentially growing a buffer layer, a U-shaped GaN layer, an N-type GaN layer, a multi-quantum well active region layer, a low-temperature P-type GaN layer, a p-type AlGaN superlattice layer and a high-temperature P-type GaN layer on an AlN substrate; S2: growing a current spreading layer with a thickness of 5-10 nm on the high-temperature P-type GaN layer to obtain a GaN-based epitaxial layer; The current spreading layer is a P-InGaN / MgN / GaN superlattice.

2. The method of claim 1, wherein the GaN-based epitaxial layer is grown by metal organic chemical vapor deposition (MOCVD) or molecular beam epitaxy (MBE). The period of the P-InGaN / MgN / P-GaN superlattice is 5-10, the thickness of a single period of the P-InGaN / MgN / P-GaN superlattice is 1-2 nm, and the thickness ratio of P-InGaN / MgN / P-GaN in a single period is 2:1:

1.

3. The method of claim 1, wherein the GaN-based epitaxial layer is grown by metal organic chemical vapor deposition (MOCVD) or molecular beam epitaxy (MBE). The doping concentration of Mg in the current spreading layer is 1E+18-5E+19 atom / cm 3 The doping concentration of In is 1E+19-2E+20 atom / cm 3 .

4. The method of claim 1, wherein the GaN-based epitaxial layer is grown by metal-organic chemical vapor deposition (MOCVD) or molecular beam epitaxy (MBE). The growth of the current spreading layer is performed in a reaction chamber with a temperature of 700-800 DEG C, a pressure of 500-1000 mbar, 60000-75000 sccm of NH3, 25-50 sccm of TEGa and 300-1000 sccm of Cp2Mg, and 100-500 sccm of TMIn is intermittently introduced.

5. The method of claim 1, wherein the GaN-based epitaxial layer is grown by metal organic chemical vapor deposition (MOCVD) or molecular beam epitaxy (MBE). The growth of the buffer layer is performed in a reaction chamber with a temperature of 780-880 DEG C, a pressure of 100-200 mbar, 1-2 min of ammonia, nitrogen and 100-300 sccm of TMGa2, and a buffer layer with a thickness of 0.005-0.1 um is obtained.

6. The method of claim 1, wherein the GaN-based epitaxial layer is grown by metal-organic chemical vapor deposition (MOCVD) or molecular beam epitaxy (MBE). The growth of the U-shaped GaN layer is performed in a reaction chamber with a temperature of 1100-1300 DEG C, a pressure of 250-350 mbar, nitrogen, hydrogen, ammonia and TMGa2 are introduced; and the U-shaped GaN layer is obtained by continuously introducing for 10-14 min.

7. The method of claim 1, wherein the GaN-based epitaxial layer is grown by metal-organic chemical vapor deposition (MOCVD) or molecular beam epitaxy (MBE). The growth of the N-type GaN layer is performed in a reaction chamber with a temperature of 1000-1100 DEG C, a pressure of 500-1000 mbar, and an N-type GaN layer with a thickness of 2-3 um is obtained.

8. The method of claim 1, wherein the GaN-based epitaxial layer is grown by metal organic chemical vapor deposition (MOCVD) or molecular beam epitaxy (MBE). The growth of the multi-quantum well active region layer is performed in a reaction chamber with a temperature of 700-800 DEG C, a pressure of 500-1000 mbar, 1200-1500 sccm of TMIn is intermittently introduced while ammonia, nitrogen and 50-400 sccm of TEGa are introduced, and a periodic InGaN / GaN multi-quantum well active region layer is grown; The number of periods of the InGaN / GaN is 10-16; the thickness of the multi-quantum well active region layer is 0.15-0.2 um, and the doping concentration of In is 1E+20-2E+20 atom / cm 3 .

9. The method of claim 1, wherein the GaN-based epitaxial layer is grown by metal organic chemical vapor deposition (MOCVD) or molecular beam epitaxy (MBE). The growth of the low-temperature P-type GaN layer is performed in a reaction chamber with a temperature of 600-700 DEG C, a pressure of 300-800 mbar, 55000-65000 sccm of NH3 and 25-50 sccm of TMGa2 are introduced, and a low-temperature P-type GaN layer with a thickness of 60-90 nm is obtained.

10. The method of claim 1, wherein the GaN-based epitaxial layer is grown by metal organic chemical vapor deposition (MOCVD) or molecular beam epitaxy (MBE). The growth of the p-type AlGaN superlattice layer is carried out in a reaction cavity with a temperature of 700-950℃ and a pressure of 300-800mbar, and 30000-60000sccm of NH3, 30-50sccm of TMGa2, 1500-2000sccm of Cp2Mg and 150-200sccm of TMAl are introduced to grow a periodic AlGaN / GaN p-type AlGaN superlattice layer; The period of the AlGaN / GaN is 5-10, the single layer thickness of the AlGaN is 4-6nm, and the thickness ratio of the AlGaN and GaN layers in a single period is 1:1-3:1; the thickness of the p-type AlGaN superlattice layer is 50-70nm, the doping concentration of Mg is 1E+18-1E+19atom / cm 3 , and the doping concentration of Al is 1E+17-1E+18atom / cm 3 .

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