High light efficiency gaN-based mini LED green light epitaxial structure and preparation method thereof

Abstract

The application relates to the technical field of semiconductor light-emitting devices, in particular to a high-luminous-efficiency GaN-based Mini LED green light epitaxial structure and a preparation method thereof. The epitaxial structure comprises an active region multi-quantum well layer, an electron blocking layer and a Mg-doped first p-GaN layer which are sequentially and layerwisely arranged, and the electron blocking layer comprises an AlN / GaN superlattice structure, an AlGaN structure, an AlGaInN structure, an InN structure and an MgN structure which are sequentially and layerwisely arranged. The epitaxial structure is provided with the electron blocking layer structure under the active region multi-quantum well layer, the electron blocking layer plays the roles of electron blocking, preventing electron overflow and increasing hole injection by sequentially and layerwisely arranging the AlN / GaN superlattice structure, the AlGaN structure and the AlGaInN structure, then the InN structure is arranged to realize hole acceleration, finally the MgN structure is arranged to provide holes and increase the injection of the holes, so that the light-emitting recombination efficiency is effectively improved, and the purpose of improving the luminous efficiency is achieved.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of semiconductor light-emitting devices, in particular to a high-luminous-efficiency GaN-based Mini LED green light epitaxial structure and a preparation method thereof. BACKGROUND

[0002] A light-emitting diode (LED) converts electric energy into light energy by releasing energy through electron and hole recombination to realize light emission. With the continuous progress and development of science and technology, light-emitting diodes are widely used in the fields of lighting and display. With the increasing requirements of industrial production on the display brightness, contrast and resolution of light-emitting diodes, sub-millimeter light-emitting diodes-Mini LED emerge as the times require. Mini LED designs the light-emitting diode structure to be thin, small and arrayed, and reduces the pixel distance from millimeter level to micrometer level, which shows great advantages in brightness, contrast and reliability.

[0003] The industrial production of light-emitting diodes is mainly based on blue-green light diodes. A preparation method of a green light epitaxial structure is disclosed in Chinese Patent Application No. 202110485368.1, which adopts an electron blocking layer of U-AlGaN structure to improve the luminous efficiency. However, the use of the above U-AlGaN structure to improve the luminous efficiency is only applicable to ordinary LEDs. For Mini LED under small current, the U-AlGaN structure will still seriously affect the light efficiency of Mini LED. SUMMARY

[0004] The technical problem to be solved by the application is to provide a high-luminous-efficiency GaN-based Mini LED green light epitaxial structure and a preparation method thereof.

[0005] In order to solve the above technical problem, the technical scheme adopted by the application is as follows: a high-luminous-efficiency GaN-based Mini LED green light epitaxial structure, comprising an active region multi-quantum well layer, an electron blocking layer and a Mg-doped first p-GaN layer which are sequentially stacked, wherein the electron blocking layer comprises an AlN / GaN superlattice structure, an AlGaN structure, an AlGaInN structure, an InN structure and an MgN structure which are sequentially stacked.

[0006] Another technical scheme adopted by the application is a preparation method of the high-luminous-efficiency GaN-based Mini LED green light epitaxial structure, wherein the growth of the electron blocking layer is carried out in a reaction chamber. 3-10 cycles of AlN / GaN superlattice structure are sequentially grown on the surface of the active region multi-quantum well layer, and then the AlGaN structure, the AlGaInN structure, the InN structure and the MgN structure are sequentially grown. The temperature of the reaction chamber is 850-950 DEG C, the pressure is 180-220 Torr, and the V / III molar ratio under N2 carrier gas is 100-300.

[0007] The beneficial effect of the present application is that the epitaxial structure of the present application sets an electron blocking layer structure under the active region multi-quantum well layer, which plays the roles of electron blocking, preventing electron overflow and increasing hole injection through the AlN / GaN superlattice structure, AlGaN structure and AlGaInN structure set by layering in sequence, then sets an InN structure to realize hole acceleration, and finally sets an MgN structure to provide holes and increase hole injection, thereby effectively improving the light emitting recombination efficiency and achieving the purpose of improving the light efficiency. DETAILED DESCRIPTION

[0008] To explain the technical content, purposes and effects of the present application in detail, the following embodiments are described.

[0009] A high light efficiency GaN-based Mini LED green light epitaxial structure, comprising an active region multi-quantum well layer, an electron blocking layer and an Mg-doped first p-GaN layer set by layering in sequence, the electron blocking layer comprising an AlN / GaN superlattice structure, an AlGaN structure, an AlGaInN structure, an InN structure and an MgN structure set by layering in sequence.

[0010] From the above description, the beneficial effect of the present application is that the epitaxial structure of the present application adopts a brand-new electron blocking layer structure, which comprises an AlN / GaN superlattice structure, an AlGaN structure, an AlGaInN structure, an InN structure and an MgN structure set by layering in sequence, wherein the AlN / GaN superlattice structure, the AlGaN structure and the AlGaInN structure play the role of electron blocking to prevent electron overflow, and at the same time, the energy level of the AlN / GaN superlattice structure is higher than that of the AlGaInN structure, which can increase the injection of holes; the InN structure plays the role of hole acceleration, the MgN structure provides holes and increases the injection of holes, and the AlN / GaN superlattice structure, the AlGaN structure, the AlGaInN structure, the InN structure and the MgN structure set by layering can effectively improve the light emitting recombination efficiency, thereby improving the light efficiency.

[0011] Further, an AlN substrate, an AlGaN / GaN buffer layer, a high-temperature non-doped UGaN layer, a high-temperature doped NGaN layer, an n-AlGaN layer, a multi-period Si-doped NGaN layer, a superlattice InGaN / GaN stress release layer, a multi-quantum well active region layer, an electron blocking layer, an Mg-doped first p-GaN layer, a p-AlGaN layer and a second p-GaN layer are set by layering in sequence.

[0012] From the above description, the application realizes the effects of reducing voltage and improving light efficiency by sequentially stacking the AlN substrate, the AlGaN / GaN buffer layer, the high-temperature undoped UGaN layer, the high-temperature doped NGaN layer, the n-AlGaN layer, the multi-period Si-doped NGaN layer, the superlattice InGaN / GaN stress release layer, the multi-quantum well active region layer, the electron blocking layer, the Mg-doped first p-GaN layer, the p-AlGaN layer and the second p-GaN layer.

[0013] Specifically, the AlGaN / GaN buffer layer can balance the lattice mismatch between the GaN lattice and the substrate; the high-temperature undoped UGaN layer can form a polycrystalline / single-crystal GaN buffer layer from an amorphous buffer layer at low temperature through high temperature; the high-temperature doped NGaN layer is provided to reduce dislocations, voltage and improve ESD; the n-AlGaN layer can block the extension of defects of the substrate layer and improve the crystal quality; the multi-period Si-doped NGaN layer provides an electron-providing layer, which has an influence on voltage, ESD and brightness; the superlattice InGaN / GaN stress release layer is an overlayer between the N-type GaN and the multi-quantum well, which mainly releases stress, blocks N-GaN and defects and dislocations generated before; the electron blocking layer can prevent electron overflow; the Mg-doped first p-GaN layer can improve brightness and realize interface processing of the quantum well to the p-AlGaN; the p-AlGaN layer is a high-energy step electron blocking layer of a normal structure, which can prevent electron overflow; and the second p-GaN layer provides a hole and realizes ohmic contact.

[0014] Another technical solution of the application is that: the preparation method of the high-efficiency GaN-based Mini LED green light epitaxial structure, the growth of the electron blocking layer is carried out in a reaction chamber, 3-10 cycles of AlN / GaN superlattice structures are sequentially grown on the surface of the active region multi-quantum well layer, and then AlGaN structures, AlGaInN structures, InN structures and MgN structures are sequentially grown, the temperature of the reaction chamber is 850-950 DEG C, the pressure is 180-220 Torr, and the V / III molar ratio under the N2 carrier gas is 100-300.

[0015] From the above description, in the preparation process of the electron blocking layer, a higher growth temperature is used to ensure the lattice quality, and a lower pressure and V / III molar ratio are used to improve the growth rate. Too many cycles of the AlN / GaN superlattice structure will cause the thickness to be too thick and the voltage to be high, and too few cycles will cause the brightness to be low, so the number of cycles of the AlN / GaN superlattice structure is limited to 3-10.

[0016] Further, the thickness of the electron blocking layer is 7-12 nm, the thickness of the AlN / GaN superlattice structure is 2-3 nm, and the thickness of AlN in the AlN / GaN superlattice structure is the same as that of GaN.

[0017] From the above description, the electron blocking layer is too thin, the brightness is reduced, and the voltage is increased, so the thickness of the electron blocking layer is limited to 7-12nm.

[0018] Further, the thickness of the AlN / GaN superlattice structure is 2-3nm, and the thickness of AlN in the AlN / GaN superlattice structure is the same as the thickness of GaN.

[0019] Further, the thickness of the AlGaN structure is 1-2nm, the thickness of the AlGaInN structure is 1-2nm, the thickness of the InN structure is 1-2nm, and the thickness of the MgN structure is 2-3nm.

[0020] From the above description, the thickness of the AlGaInN structure is too thick, the voltage is increased, and too thin will cause poor surface treatment when InN is subsequently grown, and there is a risk of electric leakage. The InN structure is a hole acceleration layer that activates Mg, and the InN structure is too thick and the surface is easy to roughen, and too thin is not conducive to the injection of Mg. The MgN structure will lead to voltage increase and leakage channel, and too thin will reduce the brightness and cannot play the role of Mg preposition.

[0021] Further, the Al doping concentration in the electron blocking layer is 1x10 18 -1x10 21 cm -3 .

[0022] From the above description, the Al content is too high, the voltage is increased, and the content is too low, the brightness will be reduced, in order to balance the voltage and the brightness, the Al doping concentration in the electron blocking layer is limited to 1x10 18 -1x10 21 cm -3 .

[0023] Further, the Al doping concentration of the AlN / GaN superlattice structure is 1x10 20 -1x10 21 cm -3 , the Al doping concentration of the AlGaN structure is 1x10 19 -1x10 21 cm -3 , and the Al doping concentration of the AlGaInN structure is 1x10 18 -1x10 19 cm -3 .

[0024] From the above description, the Al doping concentration of the AlN / GaN superlattice structure, the AlGaN structure and the AlGaInN structure of the electron blocking layer of the application is reduced in turn, so that the energy level is reduced in turn, which is conducive to the injection of holes in the subsequent MgN structure.

[0025] Further, the In doping concentration in the electron barrier layer is 5×10 17 ~1×10 19 cm -3 .

[0026] From the above description, too high In doping concentration in the electron barrier layer will cause the surface of the electron barrier layer to be blackened and affect the brightness, and too low In doping concentration will reduce the brightness, therefore the In doping concentration in the electron barrier layer is controlled to be 5×10 17 ~1×10 19 cm -3 .

[0027] Further, the In doping concentration in the AlGaInN structure is 5×10 17 ~10×10 17 cm -3 , and the In doping concentration in the InN structure is 1×10 18 ~1×10 19 cm -3 .

[0028] From the above description, the In doping concentration in the InN structure is higher than that in the AlGaInN structure, which can activate the Mg in the subsequent MgN structure.

[0029] Further, the Mg doping concentration in the MgN structure is 1×10 18 ~2×10 19 cm -3 .

[0030] From the above description, too high or too low Mg doping concentration will affect the brightness, therefore the Mg doping concentration in the MgN structure is controlled to be 1×10 19 ~1.5×10 19 cm -3 .

[0031] Further, the AlGaN / GaN buffer layer is grown in a reaction chamber, the temperature of the reaction chamber is 700~900℃, the pressure is 100~300Torr, the rotation speed is 800~1200rpm, H2 carrier gas is used, and the V / Ⅲ molar ratio is 60~100.

[0032] Further, the high-temperature undoped UGaN layer is grown in a reaction chamber, the temperature of the reaction chamber is 1050~1100℃, the pressure is 150~300Torr, the rotation speed is 800~1200rpm, H2 carrier gas is used, the V / Ⅲ molar ratio is 100~300, and the thickness of the high-temperature undoped UGaN layer is 1~3μm.

[0033] Further, the growth of the high-temperature doped NGaN layer is performed in a reaction chamber with a temperature of 1050-1100 °C, a pressure of 150-300 Torr, a rotation speed of 800-1200 rpm, H2 carrier gas, and a V / III molar ratio of 100-300, and the high-temperature doped NGaN layer has a thickness of 0.5-2 μm and a Si doping concentration of 5x1018-1Ox1019cm-3. 18 18 -3

[0034] Further, the n-AlGaN layer has a thickness of 10-100 nm.

[0035] Further, the growth of the multi-period Si-doped NGaN layer is performed in a reaction chamber with a temperature of 950-1050 °C, a pressure of 150-200 Torr, a rotation speed of 1200 rpm, H2 carrier gas, and a V / III molar ratio of 100-300, and the n-AlGaN layer has a thickness of 1.5-2 μm.

[0036] Further, the growth of the superlattice InGaN / GaN stress release layer is performed in a reaction chamber with a temperature of 850-950 °C, a pressure of 150-200 Torr, a rotation speed of 600 rpm, H2 carrier gas, and a V / III molar ratio of 1000-5000.

[0037] Further, the growth of the multi-quantum well active region layer is performed in a reaction chamber with a temperature of 850-950 °C, a well / barrier temperature difference of 100-150 °C, a pressure of 200 Torr, and H2 carrier gas.

[0038] Further, the growth of the Mg-doped first p-GaN layer is performed in a reaction chamber with a temperature of 750-800 °C, a pressure of 200 Torr, a rotation speed of 600 rpm, H2 carrier gas, and a Mg doping concentration of 5x1018-1.5x1019cm-3. 19 20 -3

[0039] Further, the growth of the p-AlGaN layer is performed in a reaction chamber with a temperature of 950-1000 °C, a pressure of 100-150 Torr, a rotation speed of 1000 rpm, H2 carrier gas, a thickness of 10-100 nm, a Mg doping concentration of 1x1018-2x1019cm-3, and an Al doping concentration of 1x1018-1x1019cm-3. 18 20 -3 19 21 cm​​​​​​​​​​-3 .

[0040] Further, the second p-GaN layer is grown in a reaction chamber with a temperature of 900-1050 DEG C, a thickness of 10-50 nm, and a Mg doping concentration of 1x1019-1x1020 cm-3. 18 ~1x10 20 cm -3 .

[0041] Embodiment one of the present application is a preparation method of a high light efficiency GaN-based Mini LED green light epitaxial structure, comprising the following steps:

[0042] S1: placing an AlN substrate in a reaction chamber.

[0043] S2: growing an AlGaN / GaN buffer layer on the AlN substrate, with a reaction chamber temperature of 800 DEG C, a pressure of 200 Torr, a rotation speed of 1000 rpm, H2 carrier gas, and a V / III molar ratio of 70.

[0044] S3: growing a high-temperature undoped UGaN layer on the AlGaN / GaN buffer layer, with a reaction chamber temperature of 1000 DEG C, a pressure of 200 Torr, a rotation speed of 1000 rpm, H2 carrier gas, a V / III molar ratio of 200, and a thickness of the high-temperature undoped UGaN layer of 2 microns.

[0045] S4: growing a high-temperature doped NGaN layer on the high-temperature undoped UGaN layer, with a reaction chamber temperature of 1000 DEG C, a pressure of 200 Torr, a rotation speed of 1000 rpm, H2 carrier gas, a V / III molar ratio of 200, a thickness of the high-temperature doped NGaN layer of 1 micron, and a Si doping concentration of 7x1018 cm-3. 18 cm -3 .

[0046] S5: growing an n-AlGaN layer on the high-temperature doped NGaN layer, with a reaction chamber temperature of 1000 DEG C, a pressure of 100 Torr, a rotation speed of 1000 rpm, H2 carrier gas, a V / III molar ratio of 100, an Al doping concentration of 1E+17 atom / cm -3 .

[0047] S6: growing a multi-period Si-doped NGaN layer on the n-AlGaN layer, with a reaction chamber temperature of 1000 DEG C, a pressure of 1800 Torr, a rotation speed of 1200 rpm, H2 carrier gas, a V / III molar ratio of 200, a thickness of the n-AlGaN layer of 1.8 microns, and a period number of the multi-period Si-doped GaN of 80, and the periodic growth can reduce stress.

[0048] S7: growing superlattice InGaN / GaN stress release layer on the multi-period Si-doped NGaN layer, the temperature of the reaction chamber is 900 °C, the pressure is 170 Torr, the rotation speed is 600 rpm, H2 carrier gas is used, the V / III molar ratio is 3000, the number of periods of the superlattice InGaN / GaN is 7, which can reduce the dislocations and stress generated by the growth of the N layer.

[0049] S8: growing multi-quantum well active region layer on the superlattice InGaN / GaN stress release layer, the temperature of the reaction chamber is 900 °C, the well / barrier temperature difference is 120 °C, under the pressure of 200 Torr and the rotation speed of 500 rpm, H2 carrier gas is used to grow well GaN / Inx1Ga 1－x1 N / Inx2Ga 1－x2 N / GaN and barrier GaN / Al y1 Ga 1－y1 N; the multi-quantum well active region layer uses GaN / Inx1Ga 1－x1 N / Inx2Ga 1－x2 N / GaN, GaN / Al y1 Ga 1－y1 N different In component structures, the content of x1 and the content of x2 are adjusted by temperature, the well / barrier mismatch is reduced, thereby the Stark effect is relieved, and the quantum barrier uses Si-doped GaN, which can reduce dislocations.

[0050] S9: growing electron blocking layer on the multi-quantum well active region layer, first growing 5 cycles of AlN / GaN superlattice structure on the surface of the active region multi-quantum well layer in sequence, then growing AlGaN structure, AlGaInN structure, InN structure and MgN structure in sequence, the temperature of the reaction chamber is 900 °C, the pressure is 200 Torr, the rotation speed is 500 rpm, N2 carrier gas is used under the V / III molar ratio of 200; the thickness of the electron blocking layer is 8 nm, the thickness of the AlN / GaN superlattice structure is 2.5 nm, the thickness of AlN in the AlN / GaN superlattice structure is the same as that of GaN, the thickness of the AlGaN structure is 1 nm, the thickness of the AlGaInN structure is 1 nm, the thickness of the InN structure is 1 nm, and the thickness of the MgN structure is 2.5 nm; the Al doping concentration of the AlN / GaN superlattice structure is 2×10 20 cm -3 -2, the Al doping concentration of the AlGaN structure is 1×10 20 cm -3 -1, the Al doping concentration of the AlGaInN structure is 2×10 18 cm -3 -2; the In doping concentration of the AlGaInN structure is 8×10 17 cm -3 -2, and the In doping concentration of the InN structure is 2×1018 cm -3 ; Mg doping concentration of MgN structure is 1×10 19 cm -3 .

[0051] S10: growing Mg-doped first p-GaN layer on the electron barrier layer, the temperature of the reaction chamber is 780℃, the pressure is 200 Torr, the rotation speed is 600 rpm, H2 carrier gas is used, and the Mg doping concentration of the Mg-doped first p-GaN layer is 1×10 20 cm -3 .

[0052] S11: growing p-AlGaN layer on the Mg-doped first p-GaN layer, the temperature of the reaction chamber is 980℃, the pressure is 130 Torr, the rotation speed is 1000 rpm, H2 carrier gas is used, the thickness of the p-AlGaN layer is 50 nm, the Mg doping concentration is 1×10 20 cm -3 , and the Al doping concentration is 1×10 20 cm -3 .

[0053] S12: growing second p-GaN layer on the p-AlGaN layer, the temperature of the reaction chamber is 1000℃, the pressure is 200 Torr, the rotation speed is 1000 rpm, 30 sccm of TMGa and 2500 sccm of Cp2Mg are introduced, the thickness of the second p-GaN layer is 30 nm, and the Mg doping concentration is 1×10 19 cm -3 .

[0054] The comparative example one of the present application is as follows:

[0055] The difference between the comparative example one and the example one is only that S9: growing electron barrier layer on the multi-quantum well active layer, the electron barrier layer is AlGaN structure with a thickness of 2 nm, the temperature of the reaction chamber is 850℃, the pressure is 200 Torr, the rotation speed is 500 rpm, N2 carrier gas is used, the V / Ⅲ molar ratio is 100, and the Al content is 1×10 18 ~ 1×10 19 cm -3 .

[0056] The epitaxial structures of the example one and the comparative example one are respectively used to prepare LED chips (the specific steps are epitaxial wafer cleaning -> MESA -> CBL -> ITO -> MET -> PV -> electrical alloying -> COW testing -> grinding and thinning -> scribing -> sorting and full testing), and the LED chips are made into 3*6 mil LED chips. The performance of the chips is tested, and the test results are shown in Table 1.

[0057] Table 1

[0058]

[0059] As shown in Table 1, the light efficiency of the epitaxial structure prepared by the method of the present application is increased by 10.4% compared with that of Comparative Example 1, and the light efficiency is obviously improved.

[0060] Embodiment two of the present application is a high light efficiency GaN-based Mini LED green epitaxial structure prepared by the preparation method of embodiment one.

[0061] Embodiment three of the present application is a preparation method of a high light efficiency GaN-based Mini LED green epitaxial structure, and the steps are as follows:

[0062] S1: Place the AlN substrate in the reaction chamber.

[0063] S2: Grow an AlGaN / GaN buffer layer on the AlN substrate, the temperature of the reaction chamber is 700℃, the pressure is 100Torr, the rotation speed is 800rpm, H2 carrier gas is used, and the V / III molar ratio is 60.

[0064] S3: Grow a high-temperature undoped UGaN layer on the AlGaN / GaN buffer layer, the temperature of the reaction chamber is 1050℃, the pressure is 150Torr, the rotation speed is 800rpm, H2 carrier gas is used, the V / III molar ratio is 100, and the thickness of the high-temperature undoped UGaN layer is 1μm.

[0065] S4: Grow a high-temperature doped NGaN layer on the high-temperature undoped UGaN layer, the temperature of the reaction chamber is 1050℃, the pressure is 150Torr, the rotation speed is 800rpm, H2 carrier gas is used, the V / III molar ratio is 100-300, the thickness of the high-temperature doped NGaN layer is 0.5μm, and the Si doping concentration is 5×10 18 cm -3 .

[0066] S5: Grow an n-AlGaN layer on the high-temperature doped NGaN layer, the temperature of the reaction chamber is 1000℃, the pressure is 100Torr, the rotation speed is 1000rpm, H2 carrier gas is used, the V / III molar ratio is 100, the Al doping concentration is 1.3E+17atom / cm -3 , and the thickness of the n-AlGaN layer is 10nm.

[0067] S6: growing a multi-period Si-doped NGaN layer on the n-AlGaN layer, the temperature of the reaction chamber is 950°C, the pressure is 150 Torr, the rotation speed is 1200 rpm, H2 carrier gas is used, the V / III molar ratio is 100, the thickness of the n-AlGaN layer is 1.5 μm, the number of periods of the multi-period Si-doped GaN is 50, and the periodic growth can reduce stress.

[0068] S7: growing a superlattice InGaN / GaN stress release layer on the multi-period Si-doped NGaN layer, the temperature of the reaction chamber is 850°C, the pressure is 150 Torr, the rotation speed is 600 rpm, H2 carrier gas is used, the V / III molar ratio is 1000, and the number of periods of the superlattice InGaN / GaN is 5, which can reduce dislocations and stress generated by the growth of the N layer.

[0069] S8: growing a multi-quantum well active region layer on the superlattice InGaN / GaN stress release layer, the temperature of the reaction chamber is 850°C, the well / barrier temperature difference is 100°C, under the conditions of a pressure of 200 Torr and a rotation speed of 500 rpm, H2 carrier gas is used to grow well GaN / Inx1Ga 1－x1 N / Inx2Ga 1－x2 N / GaN and barrier GaN / Al y1 Ga 1－y1 N; the multi-quantum well active region layer adopts GaN / Inx1Ga 1－x1 N / Inx2Ga 1－x2 N / GaN, GaN / Al y1 Ga 1－y1 N different In components, the x1 content and the x2 content are adjusted by temperature, the well / barrier mismatch is reduced, the Stark effect is relieved, the quantum barrier adopts Si-doped GaN, and dislocations can be reduced.

[0070] S9: growing an electron blocking layer on the multi-quantum well active region layer, first growing 3 cycles of AlN / GaN superlattice structures on the surface of the active region multi-quantum well layer in sequence, then growing AlGaN structures, AlGaInN structures, InN structures and MgN structures in sequence, the temperature of the reaction chamber is 850°C, the pressure is 180 Torr, the rotation speed is 500 rpm, the V / III molar ratio is 100 under N2 carrier gas; the thickness of the electron blocking layer is 7 nm, the thickness of the AlN / GaN superlattice structure is 2 nm, the thickness of AlN in the AlN / GaN superlattice structure is the same as that of GaN, the thickness of the AlGaN structure is 1 nm, the thickness of the AlGaInN structure is 1 nm, the thickness of the InN structure is 1 nm, and the thickness of the MgN structure is 2 nm; the Al doping concentration of the AlN / GaN superlattice structure is 1×1019 cm-3, the Mg doping concentration of the AlGaN structure is 1×1019 cm-3, the Mg doping concentration of the AlGaInN structure is 1×1019 cm-3, the Mg doping concentration of the InN structure is 1×1019 cm-3, and the Mg doping concentration of the MgN structure is 1×1019 cm-3. 20 cm -3, the Al doping concentration of the AlGaN structure is 1x10 19 cm -3 , the Al doping concentration of the AlGaInN structure is 1x10 18 cm -3 ; the In doping concentration of the AlGaInN structure is 5x10 17 cm -3 , the In doping concentration of the InN structure is 1x10 18 cm -3 ; the Mg doping concentration of the MgN structure is 1x10 18 cm -3 .

[0071] S10: growing a Mg-doped first p-GaN layer on the electron barrier layer, the temperature of the reaction chamber is 750 DEG C, the pressure is 200 Torr, the rotation speed is 600 rpm, H2 is used as the carrier gas, and the Mg doping concentration of the Mg-doped first p-GaN layer is 5x10 190 cm -3 .

[0072] S11: growing a p-AlGaN layer on the Mg-doped first p-GaN layer, the temperature of the reaction chamber is 950 DEG C, the pressure is 100 Torr, the rotation speed is 1000 rpm, H2 is used as the carrier gas, the thickness of the p-AlGaN layer is 10 nm, the Mg doping concentration is 1x10 18 cm -3 , and the Al doping concentration is 1x10 19 cm -3 .

[0073] S12: growing a second p-GaN layer on the p-AlGaN layer, the temperature of the reaction chamber is 900 DEG C, the pressure is 200 Torr, the rotation speed is 1000 rpm, 25 sccm of TMGa and 2000 sccm of Cp2Mg are introduced, the thickness of the second p-GaN layer is 100 nm, and the Mg doping concentration is 1x10 18 cm -3 .

[0074] Embodiment four of the application is a preparation method of a high-light-efficiency GaN-based Mini LED green light epitaxial structure, and the steps are as follows:

[0075] S1: placing an AlN substrate in a reaction chamber.

[0076] S2: growing an AlGaN / GaN buffer layer on the AlN substrate, the temperature of the reaction chamber is 900 DEG C, the pressure is 300 Torr, the rotation speed is 1200 rpm, H2 is used as the carrier gas, and the V / III molar ratio is 100.

[0077] S3: growing high-temperature undoped UGaN layer on AlGaN / GaN buffer layer, temperature of reaction chamber is 1100°C, pressure is 300 Torr, rotation speed is 1200 rpm, H2 carrier gas is used, V / III molar ratio is 1300, thickness of high-temperature undoped UGaN layer is 3 μm.

[0078] S4: growing high-temperature doped NGaN layer on high-temperature undoped UGaN layer, temperature of reaction chamber is 1100°C, pressure is 300 Torr, rotation speed is 1200 rpm, H2 carrier gas is used, V / III molar ratio is 300, thickness of high-temperature doped NGaN layer is 2 μm, Si doping concentration is 10 x 1018 atom / cm2. 18 cm -3 .

[0079] S5: growing n-AlGaN layer on high-temperature doped NGaN layer, temperature of reaction chamber is 1000°C, pressure is 100 Torr, rotation speed is 1000 rpm, H2 carrier gas is used, V / III molar ratio is 100, Al doping concentration is 1.5E+17 atom / cm2, thickness of n-AlGaN layer is 100 nm. -3

[0080] S6: growing multi-period Si-doped NGaN layer on n-AlGaN layer, temperature of reaction chamber is 1050°C, pressure is 200 Torr, rotation speed is 1200 rpm, H2 carrier gas is used, V / III molar ratio is 300, thickness of n-AlGaN layer is 2 μm, period number of multi-period Si-doped GaN is 100, periodic growth can reduce stress.

[0081] S7: growing superlattice InGaN / GaN stress release layer on multi-period Si-doped NGaN layer, temperature of reaction chamber is 950°C, pressure is 200 Torr, rotation speed is 600 rpm, H2 carrier gas is used, V / III molar ratio is 5000, period number of superlattice InGaN / GaN is 10, which can reduce dislocation and stress generated by N layer growth.

[0082] S8: growing multi-quantum well active region layer on superlattice InGaN / GaN stress release layer, temperature of reaction chamber is 950°C, temperature difference between well and barrier is 150°C, under pressure of 200 Torr and rotation speed of 500 rpm, H2 carrier gas is used to grow well GaN / Inx1Ga 1－x1 N / Inx2Ga 1－x2 N / GaN and barrier GaN / Al y1 Ga 1－y1 N; multi-quantum well active region layer uses GaN / Inx1Ga 1－x1 N / Inx2Ga 1－x2 ​N / GaN, GaN / Al y1 Ga 1－y1 N different In component structure, x1 content and x2 content are adjusted by temperature, reducing the well barrier mismatch, thereby relieving the Stark effect, and the quantum barrier uses Si-doped GaN, which can reduce dislocations.

[0083] S9: growing an electron blocking layer on the multi-quantum well active region layer, first growing 10 cycles of AlN / GaN superlattice structure on the surface of the active region multi-quantum well layer, then growing AlGaN structure, AlGaInN structure, InN structure and MgN structure in sequence, the temperature of the reaction chamber is 950°C, the pressure is 220 Torr, the rotation speed is 500 rpm, the V / III molar ratio under N2 carrier gas is 300; the thickness of the electron blocking layer is 12 nm, the thickness of the AlN / GaN superlattice structure is 3 nm, the thickness of AlN in the AlN / GaN superlattice structure is the same as that of GaN, the thickness of the AlGaN structure is 2 nm, the thickness of the AlGaInN structure is 2 nm, the thickness of the InN structure is 2 nm, and the thickness of the MgN structure is 3 nm; the Al doping concentration of the AlN / GaN superlattice structure is 1×10 21 cm -3 -2, the Al doping concentration of the AlGaN structure is 1×10 21 cm -3 -2, the Al doping concentration of the AlGaInN structure is 1×10 19 cm -3 -2; the In doping concentration of the AlGaInN structure is 10×10 17 cm -3 -2, the In doping concentration of the InN structure is 1×10 19 cm -3 -2; the Mg doping concentration of the MgN structure is 2×10 19 cm -3 -2.

[0084] S10: growing a Mg-doped first p-GaN layer on the electron blocking layer, the temperature of the reaction chamber is 800°C, the pressure is 200 Torr, the rotation speed is 600 rpm, H2 carrier gas is used, and the Mg doping concentration of the Mg-doped first p-GaN layer is 1.5×10 20 cm -3 -2.

[0085] S11: growing a p-AlGaN layer on the Mg-doped first p-GaN layer, the temperature of the reaction chamber is 1000°C, the pressure is 150 Torr, the rotation speed is 1000 rpm, H2 carrier gas is used, the thickness of the p-AlGaN layer is 100 nm, and the Mg doping concentration is 2×10 20 cm -3, Al doping concentration is 1x10 21 cm -3 .

[0086] S12: growing a second p-GaN layer on the p-AlGaN layer, the reaction chamber temperature is 1050 DEG C, the pressure is 200 Torr, the rotation speed is 1000 rpm, 50 sccm of TMGa and 3000 sccm of Cp2Mg are input, the thickness of the second p-GaN layer is 50 nm, and Mg doping concentration is 1x10 20 cm -3 .

[0087] In conclusion, the preparation method of the high light efficiency GaN-based Mini LED green light epitaxial structure provided by the application adopts a brand-new electron blocking layer structure, in the preparation process of the electron blocking layer, in order to ensure the lattice quality, a higher growth temperature is used, in order to improve the growth rate, a lower pressure and V / III molar ratio are used. The electron blocking layer comprises an AlN / GaN superlattice structure, an AlGaN structure, an AlGaInN structure, an InN structure and an MgN structure which are sequentially stacked, wherein the AlN / GaN superlattice structure, the AlGaN structure and the AlGaInN structure play an electron blocking role to prevent electron overflow, at the same time, since the energy level of the AlN / GaN superlattice structure is higher than that of the AlGaInN structure, the injection of holes can be increased; the InN structure plays a hole acceleration role, the MgN structure provides holes and increases the injection of holes, at the same time, since the In doping concentration of the InN structure is higher than that of the AlGaInN structure, the Mg in the MgN structure can be activated. Through the AlN / GaN superlattice structure, the AlGaN structure, the AlGaInN structure, the InN structure and the MgN structure which are stacked, the light emitting recombination efficiency can be effectively improved, so that the light efficiency is improved.

[0088] The above description is only an embodiment of the application, and does not limit the patent scope of the application, any equivalent transformation made by the specification, or direct or indirect application in the related technical field, is also included in the patent protection scope of the application.

Claims

1. A high-efficiency GaN-based Mini LED green epitaxial structure, characterized in that, It includes an active region multi-quantum well layer, an electron blocking layer and a Mg-doped first p-GaN layer stacked sequentially. The electron blocking layer includes an AlN / GaN superlattice structure, an AlGaN structure, an AlGaInN structure, an InN structure and a MgN structure stacked sequentially.

2. The high-efficiency GaN-based Mini LED green epitaxial structure according to claim 1, characterized in that, The structure includes, in sequence, an AlN substrate, an AlGaN / GaN buffer layer, a high-temperature undoped UGaN layer, a high-temperature doped NGaN layer, an n-AlGaN layer, a multi-period Si-doped NGaN layer, a superlattice InGaN / GaN stress relief layer, a multi-quantum well active region layer, an electron blocking layer, a Mg-doped first p-GaN layer, a p-AlGaN layer, and a second p-GaN layer.

3. A method for fabricating a high-efficiency GaN-based Mini LED green epitaxial structure as described in claim 1 or 2, characterized in that, The growth of the electron blocking layer is carried out in a reaction chamber. First, AlN / GaN superlattice structures with 3 to 10 cycles are grown sequentially on the surface of the active region multi-quantum well layer. Then, AlGaN, AlGaInN, InN, and MgN structures are grown sequentially. The temperature of the reaction chamber is 850 to 950°C, the pressure is 180 to 220 Torr, and the V / III molar ratio is 100 to 300 under N2 carrier gas.

4. The method for fabricating a high-efficiency GaN-based Mini LED green epitaxial structure according to claim 3, characterized in that, The thickness of the electron blocking layer is 7–12 nm.

5. The method for fabricating a high-efficiency GaN-based Mini LED green epitaxial structure according to claim 3, characterized in that, The Al doping concentration in the electron blocking layer is 1×10⁻⁶. 18 ~1×10 21 cm -3 .

6. The method for fabricating a high-efficiency GaN-based Mini LED green epitaxial structure according to claim 5, characterized in that, The Al doping concentration of the AlN / GaN superlattice structure is 1×10⁻⁶. 20 ~1×10 21 cm -3 The Al doping concentration of the AlGaN structure is 1×10⁻⁶. 19 ~1×10 21 cm -3 The Al doping concentration of the AlGaInN structure is 1×10⁻⁶. 18 ~1×10 19 cm -3 .

7. The method for fabricating a high-efficiency GaN-based Mini LED green epitaxial structure according to claim 3, characterized in that, The In doping concentration in the electron blocking layer is 5 × 10⁻⁶. 17 ~1×10 19 cm -3 .

8. The method for fabricating a high-efficiency GaN-based Mini LED green epitaxial structure according to claim 7, characterized in that, The In doping concentration of the AlGaInN structure is 5 × 10⁻⁶. 17 ~10×10 17 cm -3 The In doping concentration of the InN structure is 1×10⁻⁶. 18 ~1×10 19 cm -3 .

9. The method for fabricating a high-efficiency GaN-based Mini LED green epitaxial structure according to claim 3, characterized in that, The Mg doping concentration of the MgN structure is 1×10⁻⁶. 18 ~2×10 19 cm -3 .

10. The method for fabricating a high-efficiency GaN-based Mini LED green epitaxial structure according to claim 3, characterized in that, The growth of the AlGaN / GaN buffer layer is carried out in a reaction chamber at a temperature of 700–900°C, a pressure of 100–300 Torr, a rotation speed of 800–1200 rpm, using H2 as the carrier gas, and a V / III molar ratio of 60–100.

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