LED epitaxial structure with high luminous efficiency and preparation method thereof

Abstract

The invention relates to the technical field of semiconductor materials, and discloses an LED epitaxial structure with high luminous efficiency and a preparation method of the LED epitaxial structure with high luminous efficiency. Comprising a substrate, and a buffer layer, an undoped GaN layer, an n-type doped GaN layer, a multi-quantum well layer, an electron barrier layer, a p-type doped GaN layer and a hole tunneling layer which are sequentially stacked on the substrate. By implementing the invention, a PN junction is formed in the hole tunneling layer, so that a built-in cell can be formed, the current expansion effect is effectively improved, the tunneling probability of holes can be obviously improved, the luminous efficiency of an LED is improved, and meanwhile, the working voltage can be reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor materials, and in particular to an LED epitaxial structure with high luminous efficiency and a preparation method thereof. Background Art

[0002] GaN materials have the advantages of low heat generation efficiency, radiation resistance, high breakdown voltage, electron saturation, large drift velocity and small dielectric constant. They have been widely used in the field of high-frequency, high-temperature and high-voltage electronic devices. Among them, the application of GaN materials in light-emitting diodes (LEDs) and semiconductor lasers (LDs) has become a hot topic in current research.

[0003] With the improvement of GaN-based semiconductor material quality and device manufacturing, GaN-based multi-quantum well light-emitting diodes have gradually replaced traditional incandescent lamps and fluorescent lamps. However, for LEDs with multi-quantum well structures, it is difficult to obtain p-type GaN-based materials with high hole concentrations due to the difficulty of p-type doping, as well as the difference in electron and hole transport properties. The mobility of holes is low, resulting in extremely mismatched distributions of electron and hole concentrations in multi-quantum wells, which restricts the development and application of high-power, high-efficiency LEDs.

[0004] High-efficiency LEDs need to have both high luminous efficiency and low operating voltage, and ideal n-type and p-type materials are the prerequisites for the application of high-efficiency LEDs and the basis for high-efficiency LEDs to perform well. For GaN-based LED devices that have entered commercial production, n-type doping already has a relatively mature technology. Mg is the main dopant for p-type GaN-based materials, and the acceptor (Mg) doping efficiency and activation efficiency in p-type GaN-based materials are low. Therefore, p-type doping is still an obstacle to the further development of high-efficiency LEDs. The hole concentration and hole mobility of p-type GaN-based materials are important parameters that directly affect the luminous efficiency of the device. Therefore, it is necessary to conduct in-depth research on how to improve the hole concentration and hole mobility in p-type GaN-based materials, thereby improving the luminous efficiency of LEDs.

[0005] At present, the p-type layer in the epitaxial structure of GaN-based blue-green LED is usually Mg-doped GaN. This conventional p-type GaN has low Mg doping efficiency, low activation efficiency, and low hole mobility, resulting in low hole concentration in the multi-quantum well, which is difficult to meet the application of high-efficiency LED. The methods to increase the hole concentration in the quantum well are: 1. Increase the doping concentration of Mg, usually by directly increasing the doping flow of Mg, and too high Mg doping concentration will cause serious degradation of crystal quality; 2. Increase the activation efficiency of Mg. Due to the high activation energy of Mg, the commonly used activation methods are furnace annealing and furnace annealing, and the activation efficiency is only about 1-2%. The current method has low activation efficiency of Mg and no more efficient activation method has been found; 3. Increase the mobility of holes. There are relatively few studies on improving the mobility of holes. Usually, the mobility of holes is increased by reducing the barrier height of the electron blocking layer. The reduction of the barrier height of the electron blocking layer will also cause more electrons to overflow to the p-type layer, resulting in a decrease in the electron-hole overlap rate in the quantum well. Summary of the invention

[0006] The technical problem to be solved by the present invention is to provide an LED epitaxial structure with high luminous efficiency and a preparation method thereof, which can improve the mobility of holes and increase the injection efficiency of holes in quantum wells, thereby improving the luminous efficiency of LEDs.

[0007] In order to solve the above technical problems, the first aspect of the present invention provides an LED epitaxial structure with high luminous efficiency, characterized in that it includes a substrate, a buffer layer, an undoped GaN layer, an n-type doped GaN layer, a multi-quantum well layer, an electron blocking layer, a p-type doped GaN layer and a hole tunneling layer stacked in sequence on the substrate;

[0008] The hole tunneling layer includes a p-type doped InGaN layer, an InSb layer and an n-type doped InGaN layer which are stacked in sequence from bottom to top.

[0009] As an improvement of the above solution, the doping concentration in the p-type doped InGaN layer is greater than the doping concentration in the p-type doped GaN layer.

[0010] As an improvement of the above solution, the doping element in the p-type doped InGaN layer is Mg, and the doping concentration is 1×10 20 cm -3 ~5×10 21 cm -3 .

[0011] As an improvement of the above solution, the In component in the p-type doped InGaN layer accounts for 0.1-0.3.

[0012] As an improvement of the above solution, the In component in the n-type doped InGaN layer accounts for 0.2-0.6.

[0013] As an improvement of the above solution, the proportion of In component in the p-type doped InGaN layer is smaller than the proportion of In component in the n-type doped InGaN layer.

[0014] As an improvement of the above solution, the thickness of the p-type doped InGaN layer is 10nn~50nm;

[0015] The thickness of the InSb layer is 1 nm to 5 nm;

[0016] The thickness of the n-type doped InGaN layer is 5nm-20nm.

[0017] As an improvement of the above solution, the doping element in the n-type doped InGaN layer is Si, and the doping concentration is 1×10 20 cm -3 ~5×10 21 cm -3 .

[0018] As an improvement of the above solution, the growth temperature of the p-type doped InGaN layer is 800° C. to 900° C. and the pressure is 100 torr to 200 torr;

[0019] The growth temperature of the InSb layer is 400° C. to 600° C., and the growth pressure is 100 torr to 200 torr;

[0020] The growth temperature of the n-type doped InGaN layer is 800° C. to 900° C., and the growth pressure is 100 torr to 200 torr.

[0021] The second aspect of the present invention further provides a method for preparing the LED epitaxial structure with high luminous efficiency, comprising:

[0022] providing a substrate;

[0023] growing a buffer layer on the substrate;

[0024] growing an undoped GaN layer on the buffer layer;

[0025] growing an n-type doped GaN layer on the undoped GaN layer;

[0026] growing a multi-quantum well layer on the n-type doped GaN layer;

[0027] growing an electron blocking layer on the multi-quantum well layer;

[0028] growing a p-type doped GaN layer on the electron blocking layer;

[0029] growing a hole tunneling layer on the p-type doped GaN layer;

[0030] The hole tunneling layer includes a p-type doped InGaN layer, an InSb layer and an n-type doped InGaN layer which are stacked in sequence from bottom to top.

[0031] The implementation of the present invention has the following beneficial effects:

[0032] In the present invention, a hole tunneling layer is arranged on the p-type doped GaN layer, and the hole tunneling layer includes a p-type doped InGaN layer, an InSb layer and an n-type doped InGaN layer which are stacked in sequence from bottom to top. A PN junction is formed in the hole tunneling layer, thereby forming a built-in battery. The InSb layer can greatly increase the electric field strength of the tunneling junction region, increase the tunneling probability of carriers, and thereby effectively improve the current spreading effect, which can significantly increase the tunneling probability of holes, improve the luminous efficiency of the LED and reduce the operating voltage at the same time. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 : A schematic structural diagram of an LED epitaxial structure with high luminous efficiency in the present invention.

[0034] Reference numerals:

[0035] 21-substrate; 22-buffer layer; 23-undoped GaN layer; 24-n-type doped GaN layer; 25-multiple quantum well layer; 26-electron blocking layer; 27-p-type doped GaN layer; 28-hole tunneling layer; 281-p-type doped InGaN layer; 282-InSb layer; 283-n-type doped InGaN layer. DETAILED DESCRIPTION

[0036] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention is further described in detail with specific embodiments below.

[0037] A p-type GaN contact layer is grown on the p-type doped GaN layer 27 of a conventional blue-green light emitting diode in order to increase the tunneling probability of holes, but the tunneling efficiency of holes is not high.

[0038] In order to solve the above problems, the present invention provides a LED epitaxial structure with high luminous efficiency in the first aspect. Figure 1 , comprising a substrate 21, a buffer layer 22, an undoped GaN layer 23, an n-type doped GaN layer 24, a multi-quantum well layer 25, an electron blocking layer 26, a p-type doped GaN layer 27 and a hole tunneling layer 28 stacked in sequence on the substrate 21;

[0039] The hole tunneling layer 28 includes a p-type doped InGaN layer 281 , an InSb layer 282 , and an n-type doped InGaN layer 283 which are stacked in sequence from bottom to top.

[0040] In the present invention, a hole tunneling layer 28 is provided on the p-type doped GaN layer 27, and a PN junction is formed in the hole tunneling layer 28, thereby forming a built-in battery, effectively improving the current spreading effect, significantly increasing the tunneling probability of holes, improving the luminous efficiency of the LED and reducing the operating voltage.

[0041] Furthermore, the resistance of the n-type doped InGaN layer 283 in the hole tunneling layer 28 is much smaller than the resistance of the p-type doped InGaN layer 281, and the lateral resistance of the current expansion layer is reduced, so the current expansion effect is improved. However, due to the large ionization energy of Mg, the electric field strength in the tunneling junction region is low due to the activation efficiency of Mg. The InSb layer 282 is inserted in the middle of the tunneling junction of the p-type doped InGaN layer 281 / n-type doped InGaN layer 283. The bandgap width of InSb is very small, which generates a polarization electric field, which can greatly increase the electric field strength in the tunneling junction region, thereby increasing the tunneling probability of carriers, and improving the current expansion effect at the same time, and finally improving the hole injection efficiency of the quantum well, that is, improving the radiation recombination efficiency of electrons and holes in the quantum well, resulting in an increase in the luminous efficiency of the LED and a decrease in the operating voltage.

[0042] Preferably, the doping concentration in the p-type doped InGaN layer 281 is greater than the doping concentration in the p-type doped GaN layer 27. The p-type doped InGaN layer 281 has a higher doping concentration, the space charge region becomes narrower, the electric field strength increases, and the migration rate of holes in the electric field is accelerated, so that more holes pass through the p-type doped GaN layer 27 and enter the multi-quantum well layer 25, thereby improving the recombination efficiency of electrons and holes.

[0043] Furthermore, the p-type doped InGaN layer 281 is doped with Mg at a doping concentration of 1×10 20 cm -3 ~5×10 21 cm -3 , an exemplary doping concentration is 1×10 20 cm -3 , 3×10 20 cm -3 , 5×10 20 cm -3 ,7×10 20 cm -3 ,9×10 20 cm -3 , 1×10 21 cm-3 , 3×10 21 cm -3 , 5×10 21 cm -3 , but not limited to this, if the doping concentration is too high, it will reduce the mobility of carriers and affect the collection efficiency.

[0044] Furthermore, the In component of the p-type doped InGaN layer 281 accounts for 0.1-0.3.

[0045] Furthermore, the p-type doped InGaN layer 281 has a thickness of 10 nm to 50 nm, and exemplary thicknesses are 10 nm, 15 nm, 20 nm, 25 nm, 30 nm, 35 nm, 40 nm, 45 nm, and 50 nm, but are not limited thereto.

[0046] Preferably, the thickness of the InSb layer 282 is 1 nm to 5 nm, and exemplary thicknesses are 1 nm, 1.5 nm, 2 nm, 2.5 nm, 3 nm, 3.5 nm, 4 nm, 4.5 nm, and 5 nm, but are not limited thereto.

[0047] Preferably, the doping element in the n-type doped InGaN layer 283 is Si, and the doping concentration is 1×10 20 cm -3 ~5×10 21 cm -3 , an exemplary doping concentration is 1×10 20 cm -3 , 3×10 20 cm -3 , 5×10 20 cm -3 ,7×10 20 cm -3 ,9×10 20 cm -3 , 1×10 21 cm -3 , 3×10 21 cm -3 , 5×10 21 cm -3 , but not limited to this.

[0048] Further, the In component of the n-type doped InGaN layer 283 accounts for 0.2-0.6, and exemplary component ratios are 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5, 0.55, and 0.6, but are not limited thereto.

[0049] Furthermore, the proportion of In in the p-type doped InGaN layer 281 is less than the proportion of In in the n-type doped InGaN layer 283. Within a specific In component range, when the proportion of In in the p-type doped InGaN layer 281 is limited to be less than the proportion of In in the n-type doped InGaN layer 283, the built-in electric field strength is increased by adjusting the band gap widths of the p-type doped InGaN layer 281 and the n-type doped InGaN layer 283, and at the same time, the lattice mismatch stress when stacked with the InSb layer 282 is reduced to a certain extent, the crystal quality of the epitaxial wafer is improved, thereby improving the antistatic ability of the LED chip and maintaining stable luminescence performance.

[0050] Furthermore, the thickness of the n-type doped InGaN layer 283 is 5nm to 20nm, and exemplary thicknesses are 5nm, 7.5nm, 10nm, 12.5nm, 15nm, 17.5nm, and 20nm, but not limited thereto, which can make the internal electric field distribution of the hole tunneling layer 28 uniform and further improve the tunneling efficiency.

[0051] Accordingly, the present invention also provides a method for preparing the LED epitaxial structure with high luminous efficiency, comprising:

[0052] (1) Providing a substrate 21;

[0053] Preferably, the substrate 21 may be a sapphire substrate, a Si substrate, etc. More preferably, it is a sapphire Al2O3 substrate with a (0001) crystal orientation.

[0054] (2) growing a buffer layer 22 on the substrate 21;

[0055] Preferably, the buffer layer 22 is an AlN buffer layer, and the thickness of the buffer layer 22 is 15 nm to 50 nm.

[0056] Furthermore, the buffer layer 22 is grown by PVD, the growth temperature is controlled to be 400° C. to 650° C., the sputtering power is 2000W to 4000W, the growth pressure is 1 torr to 10 torr, and Al source and N source are introduced for deposition.

[0057] Furthermore, after the growth of the buffer layer 22 is completed, an in-situ annealing treatment can be performed in MOCVD, the annealing atmosphere is H2, the annealing temperature is 1000°C to 1200°C, the annealing pressure is 150torr to 500torr, the annealing time is 5min to 10min, and the subsequent deposition processes are all performed in MOCVD.

[0058] (3) growing an undoped GaN layer 23 on the buffer layer 22;

[0059] Preferably, the undoped GaN layer 23 has a thickness of 1.0 μm to 3.0 μm.

[0060] Furthermore, in MOCVD, the growth temperature is controlled to be 1050° C. to 1200° C., the growth pressure is controlled to be 100 torr to 500 torr, and Ga source and N source are introduced for deposition.

[0061] (4) growing an n-type doped GaN layer 24 on the undoped GaN layer 23;

[0062] Preferably, the doping element of the N-type doped GaN layer 24 is Si, and the doping concentration of Si is 1×10 19 cm -3 ~1×10 20 cm -3 The thickness of the N-type doped GaN layer 24 is 1.0 μm to 3.0 μm.

[0063] Furthermore, the growth temperature is controlled to be 1100° C. to 1200° C., the growth pressure is 100 torr to 300 torr, and Si source, Ga source and N source are introduced for deposition.

[0064] (5) growing a multi-quantum well layer 25 on the n-type doped GaN layer 24;

[0065] Preferably, the multi-quantum well layer 25 is a periodic structure of alternately stacked InGaN quantum well layers and GaN quantum barrier layers, with a stacking period number of 6 to 12. In a single period, the In component of the InGaN quantum well layer is 0.1 to 0.5, the thickness of the InGaN quantum well layer is 2 nm to 4 nm, and the thickness of the GaN quantum barrier layer is 8 nm to 20 nm.

[0066] Further, the growth temperature is controlled to be 800° C. to 900° C., the growth pressure is 100 torr to 300 torr, and the In source, Ga source and N source are introduced to deposit the InGaN quantum well layer; then, the growth temperature is controlled to be 900° C. to 1000° C., the growth pressure is 100 torr to 300 torr, and the Ga source and N source are introduced to deposit the GaN quantum barrier layer to complete one growth cycle, and then the InGaN quantum well layer and the GaN quantum barrier layer are continued to be repeatedly stacked and grown periodically.

[0067] (6) growing an electron blocking layer 26 on the multi-quantum well layer 25;

[0068] Preferably, the electron blocking layer 26 is an AlGaN layer, the Al component is 0.1-0.5, and the thickness of the electron blocking layer 26 is 20nm-100nm.

[0069] Furthermore, the growth temperature is controlled to be 1000° C. to 1100° C., the growth pressure is 50 torr to 100 torr, and N source, Ga source and Al source are introduced for deposition.

[0070] (7) growing a p-type doped GaN layer 27 on the electron blocking layer 26;

[0071] Preferably, the doping element of the p-type doped GaN layer 27 is Mg, and the doping concentration of Mg is 1×10 19 cm -3 ~1×10 20 cm -3 The thickness of the p-type doped GaN layer 27 is 30 nm to 100 nm.

[0072] Furthermore, the growth temperature is controlled to be 950° C. to 1050° C., the growth pressure is controlled to be 100 torr to 600 torr, and N source, Ga source and Mg source are introduced for deposition.

[0073] (8) growing a hole tunneling layer 28 on the p-type doped GaN layer 27;

[0074] The hole tunneling layer 28 includes a p-type doped InGaN layer 281 , an InSb layer 282 , and an n-type doped InGaN layer 283 which are stacked in sequence from bottom to top.

[0075] First, the growth temperature is controlled to be 800° C. to 900° C., the growth pressure is 100 torr to 200 torr, and an In source, a Ga source and a Mg source are introduced to grow the p-type doped GaN layer 27;

[0076] Subsequently, the growth temperature is controlled to be 400° C. to 600° C., the growth pressure is 100 torr to 200 torr, and an In source and a Sb source are introduced to grow the InSb layer 282;

[0077] Finally, the growth temperature is controlled to be 800° C. to 900° C., the growth pressure is controlled to be 100 torr to 200 torr, and In source, Ga source and Si source are introduced to grow the n-type doped InGaN layer 283 .

[0078] In some preferred embodiments, the method for preparing an LED epitaxial structure with high luminous efficiency further comprises:

[0079] (9) After the epitaxial structure growth is completed, annealing treatment is performed and then the temperature is cooled to room temperature.

[0080] Preferably, the annealing treatment is performed in a N2 atmosphere, the annealing treatment temperature is 650°C to 850°C, and the treatment time is 5min to 15min.

[0081] It should be noted that the MOCVD deposition in the present invention uses Veeco C4 MOCVD (Metal Organic Chemical Vapor Deposition) equipment to realize the growth method of epitaxial wafers. A mixed gas of high-purity H2 (hydrogen) and high-purity N2 (nitrogen) is used as a carrier gas; the N source is high-purity NH3, the Al source is TMAl (trimethylaluminum), the Ga source is TMGa (trimethylgallium) or TEGa (triethylgallium), the In source is TMIn (trimethylindium), the Sb source is SbH3 (antimonide), the Si source is SiH4, and the Mg source is CP2Mg.

[0082] The present invention will be further described below with specific embodiments:

[0083] Example 1

[0084] This embodiment provides an LED epitaxial structure with high luminous efficiency, comprising a substrate, a buffer layer, an undoped GaN layer, an n-type doped GaN layer, a multi-quantum well layer, an electron blocking layer, a p-type doped GaN layer and a hole tunneling layer stacked in sequence on the substrate;

[0085] The hole tunneling layer includes a p-type doped InGaN layer, an InSb layer and an n-type doped InGaN layer which are stacked in sequence from bottom to top.

[0086] The In component of the p-type doped InGaN layer is 0.2, the doping element is Mg, and the doping concentration is 1×10 21 cm -3 , thickness is 30nm.

[0087] The thickness of the InSb layer is 3 nm.

[0088] The In component of the n-type doped InGaN layer is 0.5, the doping element is Si, and the doping concentration is 5×10 20 cm -3 , thickness is 10nm.

[0089] Its preparation method is:

[0090] (1) Providing a substrate

[0091] The substrate is a (0001) crystal orientation sapphire Al2O3 substrate.

[0092] (2) Growing a buffer layer on the substrate

[0093] The buffer layer is an AlN buffer layer with a thickness of 50 nm.

[0094] The buffer layer was grown by PVD, with the growth temperature controlled at 520°C, the sputtering power at 3000W, and the pressure at 5 torr, and Al source and N source were introduced for growth. Then, in MOCVD, under H2 atmosphere, the temperature was adjusted to 1100°C and the pressure was adjusted to 300 torr for annealing for 8 minutes.

[0095] (3) growing an undoped GaN layer on the buffer layer;

[0096] The growth temperature was adjusted to 1160° C., the growth pressure was adjusted to 250 torr, and Ga source and N source were introduced to grow the undoped GaN layer with a thickness of 2.0 μm.

[0097] (4) growing an n-type doped GaN layer on the undoped GaN layer;

[0098] The doping element of the N-type doped GaN layer is Si, and the doping concentration of Si is 5×10 19 cm -3 .

[0099] The growth temperature was adjusted to 1150° C., the growth pressure was adjusted to 200 torr, and Si source, Ga source and N source were introduced to grow the n-type doped GaN layer with a thickness of 2.0 μm.

[0100] (5) growing a multi-quantum well layer on the n-type doped GaN layer;

[0101] The multi-quantum well layer is a periodic structure of alternately stacked InGaN quantum well layers and GaN quantum barrier layers, with a stacking period number of 9. In a single period, the In component of the InGaN quantum well layer is 0.25, the thickness of the InGaN quantum well layer is 3 nm, and the thickness of the GaN quantum barrier layer is 14 nm.

[0102] The growth temperature is adjusted to 850° C. and the growth pressure is adjusted to 200 torr. N source, Ga source and In source are introduced to grow the InGaN quantum well layer. Subsequently, the temperature of the reaction chamber is controlled to 950° C., the In source is turned off, and Ga source and N source are introduced to grow the GaN quantum barrier layer to complete one cycle of growth. Subsequently, the InGaN quantum well layer and the GaN quantum barrier layer are repeatedly stacked and grown periodically.

[0103] (6) growing an electron blocking layer on the multi-quantum well layer;

[0104] The electron blocking layer is an AlGaN layer, and the Al composition is 0.3.

[0105] The growth temperature was adjusted to 1050° C., the growth pressure was adjusted to 75 torr, and N source, Ga source and Al source were introduced to grow the electron blocking layer, and the thickness of the layer was 60 nm.

[0106] (7) growing a p-type doped GaN layer on the electron blocking layer;

[0107] The doping element of the P-type doped GaN layer is Mg, and the doping concentration of Mg is 5×10 19 cm -3 .

[0108] The growth temperature was maintained at 1000° C., the growth pressure was adjusted to 350 torr, and N source, Ga source and Mg source were introduced to grow the p-type doped GaN layer with a thickness of 65 nm.

[0109] (8) growing a hole tunneling layer on the p-type doped GaN layer;

[0110] The hole tunneling layer includes a p-type doped InGaN layer, an InSb layer and an n-type doped InGaN layer which are stacked in sequence from bottom to top.

[0111] First, the growth temperature is adjusted to 850° C., the growth pressure is adjusted to 150 torr, and an In source, a Ga source, and a Mg source are introduced to grow the p-type doped GaN layer;

[0112] Subsequently, the growth temperature is adjusted to 450° C., the growth pressure is maintained at 150 torr, and an In source and an Sb source are introduced to grow the InSb layer;

[0113] Finally, the growth temperature was adjusted to 850° C., the growth pressure was maintained at 150 torr, and an In source, a Ga source, and a Si source were introduced to grow the n-type doped InGaN layer.

[0114] (9) After the epitaxial structure growth is completed, the temperature of the reaction chamber is lowered and annealing is performed in a N2 atmosphere at a temperature of 780°C for 10 minutes. The temperature is then lowered to room temperature to obtain an LED epitaxial structure with high luminous efficiency.

[0115] Embodiments 2 to 13 are basically the same as Embodiment 1, except for the relevant parameter settings of the p-type doped InGaN layer, the InSb layer and the n-type doped InGaN layer in the hole tunneling layer. The specific relevant parameters are shown in Table 1 below.

[0116] Table 1 Parameter settings of the insertion layer in Examples 1 to 13

[0117]

[0118]

[0119] Comparative Example 1

[0120] This comparative example provides a Micro-LED epitaxial structure, which is basically the same as Example 1, except that a p-type GaN contact layer is grown on the p-type doped GaN layer, and the doping concentration is 1×10 21 cm -3 .

[0121] Comparative Example 2

[0122] This comparative example provides a Micro-LED epitaxial structure, which is basically the same as Example 1, except that the hole tunneling layer includes a p-type doped InGaN layer and an n-type doped InGaN layer stacked in sequence from bottom to top.

[0123] Performance Testing

[0124] The epitaxial wafers obtained in the embodiment and the comparative example were made into 10*25μm chips for photoelectric performance testing. The specific testing method of the chip was: when the current was 120mA, the photoelectric performance test was carried out. The specific testing method of the chip was: when the current was 60mA, the luminous brightness, operating voltage and luminous wavelength of the obtained chip were tested.

[0125] Antistatic performance test: The antistatic performance of the base chip is tested using an electrostatic meter under the HBM (Human Body Model) model to test the pass ratio of the chip that can withstand reverse 6kV static electricity.

[0126] The test results are shown in Table 2 below.

[0127] Table 2 Test results of LED chips obtained in the embodiments and comparative examples

[0128]

[0129]

[0130] From the above results, it can be seen that a hole tunneling layer is arranged on the p-type doped GaN layer, and the hole tunneling layer includes a p-type doped InGaN layer, an InSb layer and an n-type doped InGaN layer stacked in sequence from bottom to top, which can significantly improve the tunneling probability of holes, improve the mobility of holes, and increase the injection efficiency of holes in the quantum well, thereby improving the luminous efficiency of the LED while reducing the operating voltage, maintaining stable luminous characteristics, and improving the antistatic performance of the LED chip.

[0131] The above disclosure is only a preferred embodiment of the present invention, which certainly cannot be used to limit the scope of the present invention. Therefore, equivalent changes made according to the claims of the present invention are still within the scope of the present invention.

Claims

1. An LED epitaxial structure with high luminous efficiency, It is characterized in that It comprises a substrate, a buffer layer, an undoped GaN layer, an n-type doped GaN layer, a multi-quantum well layer, an electron blocking layer, a p-type doped GaN layer and a hole tunneling layer which are sequentially stacked on the substrate; The hole tunneling layer includes a p-type doped InGaN layer, an InSb layer and an n-type doped InGaN layer which are stacked in sequence from bottom to top.

2. The LED epitaxial structure with high luminous efficiency as claimed in claim 1, It is characterized in that The doping concentration in the p-type doped InGaN layer is greater than the doping concentration in the p-type doped GaN layer.

3. The LED epitaxial structure with high luminous efficiency as claimed in claim 2, It is characterized in that The p-type doped InGaN layer is doped with Mg at a concentration of 1×10 20 cm -3 ~5×10 21 cm -3 .

4. The LED epitaxial structure with high luminous efficiency as claimed in claim 1, It is characterized in that The In component in the p-type doped InGaN layer accounts for 0.1-0.

3.

5. The LED epitaxial structure with high luminous efficiency as claimed in claim 1, It is characterized in that The In component in the n-type doped InGaN layer accounts for 0.2-0.

6.

6. The LED epitaxial structure with high luminous efficiency as claimed in claim 4 or 5, It is characterized in that The proportion of In component in the p-type doped InGaN layer is smaller than the proportion of In component in the n-type doped InGaN layer.

7. The LED epitaxial structure with high luminous efficiency as claimed in claim 1 or 6, It is characterized in that The thickness of the p-type doped InGaN layer is 10nm to 50nm; The thickness of the InSb layer is 1 nm to 5 nm; The thickness of the n-type doped InGaN layer is 5nm-20nm.

8. The LED epitaxial structure with high luminous efficiency as claimed in claim 1, It is characterized in that The doping element in the n-type doped InGaN layer is Si, and the doping concentration is 1×10 20 cm -3 ~5×10 21 cm -3 .

9. The LED epitaxial structure with high luminous efficiency as claimed in claim 1, It is characterized in that The growth temperature of the p-type doped InGaN layer is 800° C. to 900° C., and the pressure is 100 torr to 200 torr; The growth temperature of the InSb layer is 400° C. to 600° C., and the growth pressure is 100 torr to 200 torr; The growth temperature of the n-type doped InGaN layer is 800° C. to 900° C., and the growth pressure is 100 torr to 200 torr.

10. A method for preparing an LED epitaxial structure with high luminous efficiency as claimed in any one of claims 1 to 9, It is characterized in that include: providing a substrate; growing a buffer layer on the substrate; growing an undoped GaN layer on the buffer layer; growing an n-type doped GaN layer on the undoped GaN layer; growing a multi-quantum well layer on the n-type doped GaN layer; growing an electron blocking layer on the multi-quantum well layer; growing a p-type doped GaN layer on the electron blocking layer; growing a hole tunneling layer on the p-type doped GaN layer; The hole tunneling layer includes a p-type doped InGaN layer, an InSb layer and an n-type doped InGaN layer which are stacked in sequence from bottom to top.

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