LED epitaxial structure and preparation method thereof and LED device

Abstract

The present invention relates to the field of semiconductor devices, and in particular to an LED epitaxial structure and a preparation method thereof and an LED device. An LED epitaxial structure comprises a substrate and an epitaxial layer located on the substrate, wherein the epitaxial layer comprises a buffer layer, an N-type semiconductor layer, a channel defect composite layer, a multi-quantum well light-emitting layer and a P-type semiconductor layer sequentially arranged along the epitaxial direction, wherein the channel defect composite layer comprises a channel defect generating layer, a channel defect amplifying layer and a channel defect repairing layer sequentially arranged, and the carbon content in the channel defect generating layer is not less than 5×10 17 atoms / cm 3 The LED epitaxial structure of the present invention can more effectively alleviate the stress conduction of the bottom layer and reduce the QCSE of the active area through the cooperation of the channel defect generating layer, the channel defect amplifying layer and the channel defect repairing layer, thereby improving the radiation recombination efficiency.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor devices, and in particular to an LED epitaxial structure and a preparation method thereof, and an LED device. Background Art

[0002] A light emitting diode (LED) is a light emitting device that can efficiently convert electrical energy into light energy and emit light through the recombination of electrons and holes. It is widely used in lighting, display and other fields.

[0003] Existing mass production of LED structures conventionally uses heterogeneous substrate growth, that is, growing GaN materials on Al2O3 substrates. The stress caused by heterogeneous substrates will affect the quantum wells in the active area, causing the QCSE to increase and the radiative recombination efficiency to decrease. Conventional technology uses multiple cycles of InGaN / GaN stress buffer layers to relieve the stress transmitted to the quantum wells in the active area.

[0004] In view of this, the present invention is proposed. Summary of the invention

[0005] One object of the present invention is to provide an LED epitaxial structure to solve the problem of high stress in the active area in existing conventional LED technology; the LED epitaxial structure of the present invention can effectively alleviate the stress conduction of the bottom layer, reduce the QCSE of the active area, and thus improve the radiation recombination efficiency.

[0006] Another object of the present invention is to provide a method for preparing the LED epitaxial structure, which is simple and easy to implement, can alleviate the stress conduction of the bottom layer, reduce the QCSE of the active area, and improve the radiation recombination efficiency.

[0007] Another object of the present invention is to provide an LED device having excellent light efficiency and smaller blue shift.

[0008] In order to achieve the above-mentioned purpose of the present invention, the following technical solutions are particularly adopted:

[0009] An LED epitaxial structure comprises a substrate and an epitaxial layer on the substrate, wherein the epitaxial layer comprises a buffer layer, an N-type semiconductor layer, a channel defect composite layer, a multi-quantum well light-emitting layer and a P-type semiconductor layer sequentially arranged along the epitaxial direction, and the channel defect composite layer comprises a channel defect generating layer, a channel defect amplifying layer and a channel defect repairing layer sequentially arranged; the carbon content in the channel defect generating layer is not less than 5×10 17 atoms / cm 3 .

[0010] In some embodiments, the channel defect generating layer includes GaN.

[0011] In some embodiments, the ratio of the carbon content in the channel defect generating layer to the carbon content in the N-type semiconductor layer is greater than or equal to 2; the ratio of the carbon content in the channel defect generating layer to the carbon content in the multi-quantum well light-emitting layer is greater than or equal to 2.

[0012] In some embodiments, the channel defect generating layer further contains impurity Si, and the content of the impurity Si is not lower than the carbon content in the channel defect generating layer.

[0013] In some embodiments, the channel defect generating layer has a thickness of 10-200 nm.

[0014] In some implementations, the channel defect amplification layer includes an InGaN layer and a GaN layer, and the InGaN layer and the GaN layer are alternately stacked.

[0015] In some implementations, the number of InGaN layers and GaN layers are independently 2 to 6 layers.

[0016] In some embodiments, the thickness of the InGaN layer is 15-40Å; the thickness of the GaN layer is 50-400Å.

[0017] In some embodiments, the channel defect repairing layer includes GaN.

[0018] In some embodiments, the channel defect repair layer has a thickness of 10 to 200 nm.

[0019] In some embodiments, the buffer layer includes AlGaN.

[0020] In some embodiments, the buffer layer has a thickness of 15-25 nm.

[0021] In some embodiments, the N-type semiconductor layer includes a stacked non-doped GaN layer and a Si-doped N-type GaN layer, wherein the Si-doped N-type GaN layer has a Si doping concentration of 2×10 19 ~5×10 19 atoms / cm 3 .

[0022] In some implementations, the thickness of the N-type semiconductor layer is 3-8 μm.

[0023] In some embodiments, the multi-quantum well light-emitting layer includes an InGaN layer and a GaN layer stacked together.

[0024] In some embodiments, the thickness of the multi-quantum well light-emitting layer is 100-130 nm.

[0025] In some embodiments, the P-type semiconductor layer includes a stacked AlGaN layer and a Mg-doped P-type GaN layer, wherein the Mg-doped P-type GaN layer has a Mg doping concentration of 0.8×10 20 ~2×10 20 atoms / cm 3 .

[0026] In some embodiments, the thickness of the P-type semiconductor layer is 180-220 nm.

[0027] In some embodiments, the ratio of the In concentration of the multi-quantum well light-emitting layer to the In concentration of the defect amplification layer is not less than 3.

[0028] The method for preparing the LED epitaxial structure as described above comprises the following steps:

[0029] A substrate is provided, and a buffer layer, an N-type semiconductor layer, a channel defect generating layer, a channel defect amplifying layer, a channel defect repairing layer, a multi-quantum well light-emitting layer and a P-type semiconductor layer are sequentially grown on a surface of one side of the substrate along its epitaxial direction.

[0030] In some embodiments, the growth conditions of the channel defect generating layer include: using TMGa as the Ga source, a growth atmosphere of nitrogen, a growth temperature of 700-760° C., a growth pressure of 180-220 mbar, and growing a GaN layer.

[0031] In some implementations, the growth conditions of the channel defect amplification layer include: a growth temperature of 880-950° C., a growth pressure of 180-220 mbar, and alternately growing InGaN layers and GaN layers.

[0032] In some embodiments, the growth conditions of the channel defect repair layer include: a growth temperature of 980-1050° C., a growth pressure of 180-220 mbar, a growth atmosphere of hydrogen, and a GaN layer is grown.

[0033] In some embodiments, the growth conditions of the buffer layer include: a growth temperature of 500-600° C. to obtain an AlGaN layer, and then annealing is performed under ammonia conditions at a temperature of 1100-1200° C.

[0034] In some embodiments, the growth conditions of the N-type semiconductor layer include: first growing a GaN layer, and then growing a Si-doped N-type GaN layer, the growth temperature is 1120-1180° C., and the growth pressure is 550-650 mbar.

[0035] In some embodiments, the growth conditions of the multi-quantum well light-emitting layer include: using TEGa as a gallium source, alternately growing InGaN layers and GaN layers in sequence, the growth temperature of GaN is 850-900°C, and the growth temperature of InGaN is 750-820°C.

[0036] In some embodiments, the growth conditions of the P-type semiconductor layer include: sequentially growing an AlGaN layer and a Mg-doped P-type GaN layer, at a growth temperature of 980-1050° C. and a growth pressure of 180-220 mbar.

[0037] An LED device comprises the LED epitaxial structure, as well as a current blocking layer, a current spreading layer, an N-electrode, a P-electrode and an insulating layer; the current blocking layer is located on the surface of the P-type semiconductor layer of the LED epitaxial structure; the current spreading layer covers the P-type semiconductor layer and is located on the surface of the P-type semiconductor layer; the P-electrode is arranged on the current spreading layer and is electrically connected to the P-type semiconductor layer; the N-electrode is arranged in the N-step region and is electrically connected to the N-type semiconductor layer; the insulating layer covers the P-electrode and the N-electrode, and exposes part of the P-electrode and the N-electrode.

[0038] Compared with the prior art, the present invention has the following beneficial effects:

[0039] (1) The LED epitaxial structure of the present invention can more effectively alleviate the stress conduction of the bottom layer and reduce the QCSE of the active area through the cooperation of the channel defect generating layer, the channel defect amplifying layer and the channel defect repairing layer, thereby improving the radiation recombination efficiency.

[0040] (2) The preparation method of the LED epitaxial structure of the present invention is simple and easy. By growing a channel defect generating layer, a channel defect amplifying layer, and a channel defect repairing layer, a more sufficient stress release effect is obtained. The QCSE effect in the subsequently grown quantum well active layer is reduced, thereby reducing non-ohmic resistance, improving radiation recombination efficiency, and improving device light efficiency. At the same time, due to the alleviation of the QCSE effect, the device blue shift is smaller.

[0041] (3) The invented light-emitting diode has excellent light efficiency and smaller blue shift. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0043] Figure 1It is a structural schematic diagram of the LED epitaxial structure of the present invention;

[0044] Figure 2 It is a structural schematic diagram of the LED device of the present invention;

[0045] Figure 3 and Figure 4 The channel defect images of the channel defect amplification layer of the LED epitaxial structure of the present invention at different magnifications;

[0046] Figure 5 is a schematic top view of a channel defect composite layer of the present invention;

[0047] Figure 6 It is a side view of the channel defect composite layer of the present invention.

[0048] Reference numerals:

[0049] 1-substrate, 100-epitaxial layer, 2-buffer layer, 3-N-type semiconductor layer, 4-channel defect composite layer, 5-multi-quantum well light-emitting layer, 6-P-type semiconductor layer, 7-current blocking layer, 8-current spreading layer, 9-P electrode, 10-N electrode, 11-insulating layer. DETAILED DESCRIPTION

[0050] The embodiments of the present invention will be described in detail below in conjunction with the examples, but it will be appreciated by those skilled in the art that the following examples are only used to illustrate the present invention and should not be considered as limiting the scope of the present invention. If no specific conditions are specified in the examples, the conditions are carried out according to normal conditions or the conditions recommended by the manufacturer. If the manufacturer of the reagents or instruments used is not specified, they are all conventional products that can be obtained commercially.

[0051] According to one aspect of the present invention, the present invention relates to an LED epitaxial structure, comprising a substrate and an epitaxial layer located on the substrate, wherein the epitaxial layer comprises a buffer layer, an N-type semiconductor layer, a channel defect composite layer, a multi-quantum well light-emitting layer and a P-type semiconductor layer sequentially arranged along the epitaxial direction, and the channel defect composite layer comprises a channel defect generating layer, a channel defect amplifying layer and a channel defect repairing layer sequentially arranged; the carbon content in the channel defect generating layer is not less than 5×10 17 atoms / cm 3 .

[0052] The LED epitaxial structure of the present invention is provided with a channel defect generating layer, a channel defect amplifying layer and a channel defect repairing layer between an N-type semiconductor layer and a multi-quantum well light-emitting layer, wherein the channel defects generated by the channel defect generating layer and the channel defect amplifying layer have the characteristic of strong stress release capability, so that the stress transmitted upward from the bottom layer is fully released, and the channel defect repairing layer can repair the channel pits of the channel defects until the surface is flat; the present invention can generate channel defects using a relatively low In concentration, and can avoid the problem of newly introducing InGaN / GaN lattice mismatch stress due to high In concentration; through the cooperation of the channel defect generating layer, the channel defect amplifying layer and the channel defect repairing layer, stress conduction can be more effectively alleviated, and the QCSE of the active area can be reduced, thereby improving the radiation recombination efficiency.

[0053] In some embodiments, the channel defect generating layer comprises GaN. The carbon content in the channel defect generating layer is not less than 5×10 17 atoms / cm 3 , for example 5.5×10 17 atoms / cm 3 , 6×10 17 atoms / cm 3 ,7×10 17 atoms / cm 3 , 8×10 17 atoms / cm 3 Etc., or a range value between any two of the above. The thickness of the channel defect generating layer is 10~200nm, for example, 10nm, 15nm, 20nm, 30nm, 50nm, 70nm, 90nm, 100nm, 120nm, 150nm, 180nm, 200nm, etc., or a range value between any two of the above. In some embodiments, the channel defect generating layer also contains impurity Si, and the content of the impurity Si is not less than the carbon content in the channel defect generating layer. In some embodiments, the ratio of the carbon content in the channel defect generating layer to the carbon content in the N-type semiconductor layer is greater than or equal to 2, for example, 2, 2.2, 2.5, 2.8, 3, 3.5, etc., for example, 2~5, etc. The ratio of the carbon content in the channel defect generating layer to the carbon content in the multi-quantum well light-emitting layer is greater than or equal to 2, for example, 2, 2.5, 3, 3.5, 4, 5, etc., for example, 2~5, etc.

[0054] The channel defect generating layer of the present invention has the characteristic of not being easily filled by atoms, and the appropriate thickness can ensure the release effect of the stress transmitted upward from the bottom layer. If it is too thick, the device quality will be greatly reduced, and if it is too thin, there will not be enough base stacking faults.

[0055] In some embodiments, the channel defect is a closed ring, including but not limited to a circle, an ellipse, or an irregular shape.

[0056] In some embodiments, the channel defect amplification layer includes an InGaN layer and a GaN layer, and the InGaN layer and the GaN layer are alternately stacked. In some embodiments, the thickness of the InGaN layer is 15~40Å, such as 15Å, 20Å, 25Å, 30Å or 40Å. The thickness of the GaN layer is 50~400Å, such as 50Å, 100Å, 150Å, 200Å, 300Å or 400Å. Preferably, the thickness of the InGaN layer is 20Å; the thickness of the GaN layer is 150Å. In some embodiments, the number of layers of the InGaN layer and the GaN layer is independently 2~6 layers, such as 2 layers, 3 layers, 4 layers, 5 layers or 6 layers. The channel defect amplification layer formed by the InGaN layer and the GaN layer of the present invention is more conducive to fully releasing the stress conducted upward from the bottom layer.

[0057] In some embodiments, the channel defect repair layer includes GaN. The thickness of the channel defect repair layer is 10 to 200 nm, for example, 10 nm, 15 nm, 20 nm, 30 nm, 50 nm, 70 nm, 90 nm, 100 nm, 120 nm, 150 nm, 180 nm, 190 nm, 200 nm, etc., or a range value between any two of the above. The present invention uses a channel defect repair layer to repair the channel pits of the channel defect until the surface is flat.

[0058] In some embodiments, the buffer layer includes AlGaN. The buffer layer has a thickness of 15-25 nm, such as 15 nm, 16 nm, 18 nm, 20 nm, 22 nm, 23 nm or 25 nm, or any range between the two.

[0059] In some embodiments, the N-type semiconductor layer includes a stacked non-doped GaN layer and a Si-doped N-type GaN layer. The Si-doped N-type GaN layer has a Si doping concentration of 2×10 19 ~5×10 19 atoms / cm 3 , for example, but not limited to 2×10 19 atoms / cm 3 , 3×10 19 atoms / cm 3 , 4×10 19 atoms / cm 3 , 5×10 19 atoms / cm 3Etc., or any range value between the two. In some embodiments, the thickness of the N-type semiconductor layer is 3-8 μm, for example, it can be 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, etc., or any range value between the two. In some embodiments, the thickness of the undoped GaN layer is 1.5-4 μm, and the thickness of the Si-doped N-type GaN layer is 1.5-4 μm. The N-type semiconductor layer of the present invention can increase the current expansion capability and improve the crystal quality of the LED epitaxial structure through the cooperation of the undoped GaN layer and the Si-doped N-type GaN layer. In some embodiments, the multi-quantum well light-emitting layer includes a stacked InGaN layer and a GaN layer. The thickness of the multi-quantum well light-emitting layer is 100-130 nm, for example, it can be but not limited to 100 nm, 105 nm, 110 nm, 115 nm, 120 nm, 125 nm, 130 nm, etc., or any range value between the two. In some embodiments, the multi-quantum well light-emitting layer includes multiple pairs of stacks formed of InGaN layers and GaN layers, for example, 2 to 15 pairs, such as 2 pairs, 3 pairs, 5 pairs, 10 pairs, 12 pairs, 15 pairs, etc.

[0060] In some embodiments, the P-type semiconductor layer includes a stacked AlGaN layer (electron blocking layer) and a Mg-doped P-type GaN layer, wherein the Mg-doped P-type GaN layer has a Mg doping concentration of 0.8×10 20 ~2×10 20 atoms / cm 3 , for example, but not limited to, 0.8×10 20 atoms / cm 3 , 1×10 20 atoms / cm 3 , 1.2×10 20 atoms / cm 3 , 1.5×10 20 atoms / cm 3 , 1.8×10 20 atoms / cm 3 , 2×10 20 atoms / cm 3 In some embodiments, the thickness of the P-type semiconductor layer is 180-220 nm, for example, but not limited to, 180 nm, 185 nm, 190 nm, 195 nm, 200 nm, 205 nm, 210 nm, 215 nm, 220 nm, etc., or any range between the two.

[0061] In some embodiments, the ratio of the In concentration of the multi-quantum well light-emitting layer to the In concentration of the defect amplification layer is not less than 3, for example, 4, 5, 6, 7, 8, etc.

[0062] According to another aspect of the present invention, the present invention also relates to a method for preparing the LED epitaxial structure as described above, comprising the following steps:

[0063] A substrate is provided, and a buffer layer, an N-type semiconductor layer, a channel defect generating layer, a channel defect amplifying layer, a channel defect repairing layer, a multi-quantum well light-emitting layer and a P-type semiconductor layer are sequentially grown on a surface of one side of the substrate along its epitaxial direction.

[0064] The preparation method of the LED epitaxial structure of the present invention is simple and easy. By growing a channel defect generating layer, a channel defect amplifying layer, and a channel defect repairing layer, a more sufficient stress release effect is obtained. The QCSE effect in the subsequently grown quantum well active layer is reduced, thereby reducing non-ohmic resistance, improving radiation recombination efficiency, and improving device luminous efficiency. At the same time, due to the alleviation of the QCSE effect, the device blue shift is smaller.

[0065] In some embodiments, the growth conditions of the buffer layer include: growing an AlGaN layer on a sapphire substrate at a growth temperature of 500-600°C, such as but not limited to 500°C, 520°C, 550°C, 570°C, 580°C, 600°C, etc., or any range between the two, and then annealing under ammonia (NH3) conditions, the annealing temperature is 1100-1200°C, such as but not limited to 1100°C, 1020°C, 1050°C, 1080°C, 1200°C, etc., or any range between the two, and the AlGaN layer obtained at a low temperature is recrystallized into island seeds through annealing.

[0066] In some embodiments, the growth conditions of the N-type semiconductor layer include: after preparing the buffer layer, introducing TMGa (trimethyl gallium) to grow a three-dimensional layer with a thickness of 0.8 to 1.2 μm (for example, 0.8 μm, 1 μm, 1.2 μm, etc.) under 700 to 850 mbar (for example, 700 mbar, 720 mbar, 750 mbar, 800 mbar, 850 mbar, etc.); raising the temperature to 1120 to 1180 ° C (for example, Such as 1120℃, 1150℃, 1160℃, 1180℃, etc.), the pressure is reduced to 550~650mbar (for example 550mbar, 580mbar, 600mbar, 620mbar, 650mbar, etc.), first grow a non-doped GaN layer with a thickness of 1.5~4μm; then grow a Si-doped N-type GaN layer with a thickness of 1.5~4μm under the conditions of 1120~1180℃ and 550~650mbar.

[0067] In some embodiments, the growth conditions of the channel defect generating layer include: TMGa as Ga source, nitrogen as growth atmosphere, growth temperature of 700-760°C, for example, but not limited to 700°C, 720°C, 730°C, 750°C, 760°C, etc., or any range between the two; growth pressure of 180-220mbar, for example, but not limited to 180mbar, 190mbar, 200mbar, 210mbar, 220mbar, etc., or any range between the two. The growth conditions of the channel defect generating layer of the present invention adopt low temperature, high growth rate, and pure N2 growth conditions, so that a large number of basal stacking faults are generated in the GaN layer; under pure N2 atmosphere, the lateral diffusion rate of atoms is slow, defects are easily generated, and the generated defects are not easy to be filled by atoms.

[0068] In some embodiments, the growth conditions of the channel defect amplification layer include: a growth temperature of 880-950°C, such as but not limited to 880°C, 885°C, 890°C, 895°C, 900°C, 910°C, 920°C, 930°C, 950°C, etc., or any range between the two; a growth pressure of 180-220mbar, such as but not limited to 180mbar, 190mbar, 200mbar, 210mbar or 220mbar, etc., or any range between the two, to grow a stack of InGaN and GaN. The present invention triggers the formation and amplification of channel defects by utilizing lattice mismatch stress to form substrate stacking faults.

[0069] In some embodiments, the growth conditions of the channel defect repair layer include: a growth temperature of 980-1050°C, such as but not limited to 980°C, 1000°C, 1020°C, 1030°C, 1040°C, 1050°C, etc., or any range between the two; a growth pressure of 180-220mbar, such as but not limited to 180mbar, 190mbar, 200mbar, 210mbar or 220mbar, etc., or any range between the two; a growth atmosphere of hydrogen to grow a GaN layer. In an H2 atmosphere, the lateral diffusion rate of atoms is fast, and defects are easily filled.

[0070] In some embodiments, the growth conditions of the multi-quantum well light-emitting layer include: using TEGa as a gallium source, and alternately growing InGaN layers and GaN layers in sequence. The growth temperature of GaN is 850-900°C, for example, it can be but not limited to 850°C, 860°C, 880°C, 890°C, 900°C, etc., or any range between the two. The growth temperature of InGaN is 750-820°C, for example, it can be but not limited to 750°C, 760°C, 770°C, 780°C, 800°C, 810°C, 820°C, etc., or any range between the two.

[0071] In some embodiments, the growth conditions of the P-type semiconductor layer include: sequentially growing an AlGaN layer and a Mg-doped P-type GaN layer, a growth temperature of 980~1050°C, for example, it can be but not limited to 980°C, 990°C, 1000°C, 1050°C, etc., and a growth pressure of 180~220mbar, 1800mbar, 190mbar, 200mbar or 220mbar, etc.

[0072] In one embodiment, a method for preparing an LED epitaxial structure comprises the following steps:

[0073] (1) An AlGaN buffer layer with a thickness of 15-25 nm is grown on the surface of a sapphire substrate at 500-600°C.

[0074] (2) Annealing treatment is performed in an NH3 atmosphere, and the temperature is raised to 1100~1200℃ to allow the low-temperature AlGaN to recrystallize into island-shaped seed crystals.

[0075] (3) TMGa is introduced and a 0.8~1.2μm thick three-dimensional layer is grown at a pressure of 700~850mbar.

[0076] (4) The temperature is raised to 1120~1180℃, the pressure is reduced to 550~650mbar, and a non-doped GaN layer with a thickness of 1.5~4μm is grown; at a temperature of 1120~1180℃ and a pressure of 550~650mbar, a Si-doped N-type GaN layer with a thickness of 1.5~4μm is grown on the surface of the non-doped GaN layer to obtain an N-type semiconductor layer.

[0077] (5) Cooling to 700-760°C, 180-220 mbar pressure, pure N2 atmosphere, using TMGa as Ga source, growing a channel defect generating layer (GaN layer) on the N-type semiconductor layer; the carbon content in the channel defect generating layer is not less than 5×10 17 atoms / cm 3; The thickness of the channel defect generating layer is 10-200 nm. The ratio of the carbon content in the channel defect generating layer to the carbon content in the N-type semiconductor layer is greater than or equal to 2; The ratio of the carbon content in the channel defect generating layer to the carbon content in the subsequently prepared multi-quantum well light-emitting layer is greater than or equal to 2.

[0078] (6) Raise the temperature to 880-950°C and grow 2-6 pairs of InGaN layers and GaN layers stacked in sequence under the conditions of 180-220 mbar to obtain a channel defect amplification layer.

[0079] (7) Raise the temperature to 980-1050°C, 180-220 mbar pressure, and grow a channel defect repair layer (GaN layer) in a pure H2 atmosphere to repair the channel pits of the channel defects until the surface is flat; the thickness of the channel defect repair layer is 10-200 nm.

[0080] (8) A multi-quantum well light-emitting layer is grown on the surface of the channel defect repair layer. The growth temperature of the GaN barrier layer is 850-900°C, and the growth temperature of the InGaN well layer is 750-820°C. The gallium source used for the InGaN well layer and the GaN barrier layer is TEGa.

[0081] (9) Raise the temperature to 980~1050℃ and grow a P-type AlGaN electron blocking layer under a pressure of 180~220mbar; then turn off the aluminum source, maintain the same temperature and pressure as those for growing the P-type AlGaN electron blocking layer, and continue to grow a Mg-doped P-type GaN layer, where the Mg doping concentration in the Mg-doped P-type GaN layer is 0.8×10 20 ~2×10 20 atoms / cm 3 , the total thickness is 180~220nm.

[0082] According to another aspect of the present invention, the present invention also relates to a light-emitting diode, comprising the LED epitaxial structure, as well as a current blocking layer, a current spreading layer, an N electrode, a P electrode and an insulating layer; the current blocking layer is located on the surface of the P-type semiconductor layer of the LED epitaxial structure; the current spreading layer covers the P-type semiconductor layer and is located on the surface of the P-type semiconductor layer; the P electrode is arranged on the current spreading layer and is electrically connected to the P-type semiconductor layer; the N electrode is arranged in the N step region and is electrically connected to the N-type semiconductor layer; the insulating layer covers the P electrode and the N electrode, and exposes part of the P electrode and the N electrode.

[0083] The light emitting diode of the present invention has excellent light efficiency and smaller blue shift.

[0084] The following is further explained in conjunction with specific embodiments.

[0085] Example 1

[0086] This embodiment provides an LED epitaxial structure, such as Figure 1 As shown, it includes a substrate 1 and an epitaxial layer 100 located on the substrate 1, wherein the epitaxial layer 100 includes a buffer layer 2, an N-type semiconductor layer 3, a channel defect composite layer 4, a multi-quantum well light-emitting layer 5 and a P-type semiconductor layer 6 arranged in sequence along the epitaxial direction, and the top view of the channel defect composite layer 4 is as shown Figure 5 As shown, the side view is Figure 6 As shown; it includes a channel defect generating layer, a channel defect amplifying layer and a channel defect repairing layer which are arranged in sequence.

[0087] The buffer layer 2 is AlGaN, and the thickness of the buffer layer 2 is 20 nm. The N-type semiconductor layer 3 includes a stacked non-doped GaN layer and a Si-doped N-type GaN layer, and the Si doping concentration in the Si-doped N-type GaN layer is 3×10 19 atoms / cm 3 The thickness of the non-doped GaN layer is 2 μm, and the thickness of the Si-doped N-type GaN layer is 2 μm. The channel defect generation layer is GaN with a thickness of 30 nm and a carbon content of 6×10 17 atoms / cm 3 , the channel defect generation layer also contains impurity Si, the content of impurity Si is not less than the carbon content in the channel defect generation layer, and the corresponding silicon source is silane; the ratio of the carbon content in the channel defect generation layer to the carbon content in the N-type semiconductor layer 3 is 2.6; the ratio of the carbon content in the channel defect generation layer to the carbon content in the multi-quantum well light-emitting layer 5 is 3. The channel defect amplification layer includes 3 pairs of stacked InGaN layers and GaN layers, the InGaN layer thickness is 20Å; the GaN layer thickness is 150Å; the channel defect repair layer is GaN, and the channel defect repair layer contains impurity Si, the content of impurity Si is not less than the carbon content in the defect repair layer, and the thickness is 55nm. The multi-quantum well light-emitting layer 5 includes 10 pairs of stacked InGaN layers and GaN layers, the single layer thickness of the InGaN layer is 2nm, and the single layer thickness of the GaN layer is 10nm. The P-type semiconductor layer 6 includes stacked AlGaN and Mg-doped P-type GaN layers, and the Mg doping concentration in the Mg-doped P-type GaN layer is 1×10 20 atoms / cm 3 , the thickness of the P-type semiconductor layer 6 is 200 nm.

[0088] The channel defect images at different magnifications in this embodiment are as follows: Figure 3 and Figure 4 shown.

[0089] The method for preparing the LED epitaxial structure of this embodiment includes the following steps:

[0090] (1) An AlGaN buffer layer 2 with a thickness of 20 nm is grown on the surface of a sapphire substrate 1 at 550°C.

[0091] (2) Annealing treatment is performed in an NH3 atmosphere, and the temperature is raised to 1110°C to allow the low-temperature AlGaN to recrystallize into island-shaped seed crystals.

[0092] (3) TMGa is introduced and a three-dimensional layer with a thickness of 1 μm is grown at a pressure of 800 mbar.

[0093] (4) The temperature is raised to 1150°C and the pressure is reduced to 600 mbar, and a non-doped GaN layer with a thickness of 2 μm is grown. Under the conditions of a temperature of 1150°C and a pressure of 600 mbar, a Si-doped N-type GaN layer with a thickness of 2 μm is grown on the surface of the non-doped GaN layer to obtain an N-type semiconductor layer 3.

[0094] (5) The temperature is lowered to 750°C, the pressure is 200 mbar, and a pure N2 atmosphere is used. TMGa is used as a Ga source to grow a channel defect generating layer (GaN layer) on the N-type semiconductor layer 3.

[0095] (6) Raising the temperature to 880°C and under a pressure of 200 mbar, three pairs of sequentially stacked InGaN layers and GaN layers are grown to obtain a channel defect amplification layer.

[0096] (7) Raise the temperature to 980°C, 200 mbar pressure, and grow a channel defect repair layer (GaN layer) in a H2 atmosphere to repair the channel pits of the channel defects until the surface is flat.

[0097] (8) A multi-quantum well light-emitting layer 5 is grown on the surface of the channel defect repair layer. The growth temperature of the GaN barrier layer is 870° C., and the growth temperature of the InGaN well layer is 790° C. The gallium source used for the InGaN well layer and the GaN barrier layer is TEGa.

[0098] (9) Raise the temperature to 1000°C and grow a P-type AlGaN electron blocking layer under a pressure of 200 mbar. Then turn off the aluminum source, maintain the same temperature and pressure as those used to grow the P-type AlGaN electron blocking layer, and continue to grow a Mg-doped P-type GaN layer, where the Mg doping concentration in the Mg-doped P-type GaN layer is 1×10 20 atoms / cm 3 , with a total thickness of 200nm.

[0099] Example 2

[0100] The present embodiment provides an LED epitaxial structure, including a substrate 1 and an epitaxial layer 100 located on the substrate 1, wherein the epitaxial layer 100 includes a buffer layer 2, an N-type semiconductor layer 3, a channel defect composite layer 4, a multi-quantum well light-emitting layer 5 and a P-type semiconductor layer 6 arranged in sequence along the epitaxial direction, and the channel defect composite layer 4 includes a channel defect generating layer, a channel defect amplifying layer and a channel defect repairing layer arranged in sequence.

[0101] The buffer layer 2 is AlGaN, and the thickness of the buffer layer 2 is 20 nm. The N-type semiconductor layer 3 includes a stacked non-doped GaN layer and a Si-doped N-type GaN layer, and the Si doping concentration in the Si-doped N-type GaN layer is 4×10 19 atoms / cm 3 The thickness of the non-doped GaN layer is 3 μm, and the thickness of the Si-doped N-type GaN layer is 3 μm. The channel defect generation layer is GaN with a thickness of 45 nm and a carbon content of 7×10 17 atoms / cm 3 , the channel defect generating layer also contains impurity Si, the content of impurity Si is not less than the carbon content in the channel defect generating layer, and the impurity Si originates from silane; the ratio of the carbon content in the channel defect generating layer to the carbon content in the N-type semiconductor layer 3 is 2.8; the ratio of the carbon content in the channel defect generating layer to the carbon content in the multi-quantum well light-emitting layer 5 is 3. The channel defect amplification layer includes 3 pairs of stacked InGaN layers and GaN layers, the thickness of the InGaN layer is 20Å; the thickness of the GaN layer is 150Å; the channel defect repair layer is GaN, and the channel defect repair layer contains impurity Si, the content of impurity Si is not less than the carbon content in the defect repair layer, and the thickness is 70nm. The multi-quantum well light-emitting layer 5 includes 10 pairs of stacked InGaN layers and GaN layers, the single layer thickness of the InGaN layer is 2nm, and the single layer thickness of the GaN layer is 11nm. The P-type semiconductor layer 6 includes a stacked AlGaN layer and a Mg-doped P-type GaN layer. The Mg-doped P-type GaN layer has a Mg doping concentration of 1.5×10 20 atoms / cm 3 , the thickness of the P-type semiconductor layer 6 is 180 nm.

[0102] The method for preparing the LED epitaxial structure of this embodiment includes the following steps:

[0103] (1) An AlGaN buffer layer 2 with a thickness of 20 nm is grown on the surface of a sapphire substrate 1 at 550°C.

[0104] (2) Annealing treatment is performed in an NH3 atmosphere, and the temperature is raised to 1110°C to allow the low-temperature AlGaN to recrystallize into island-shaped seed crystals.

[0105] (3) TMGa is introduced and a three-dimensional layer with a thickness of 1 μm is grown at a pressure of 800 mbar.

[0106] (4) The temperature is raised to 1150°C and the pressure is reduced to 600 mbar, and a non-doped GaN layer with a thickness of 3 μm is grown. Under the conditions of a temperature of 1150°C and a pressure of 600 mbar, a Si-doped N-type GaN layer with a thickness of 3 μm is grown on the surface of the non-doped GaN layer to obtain an N-type semiconductor layer 3.

[0107] (5) The temperature is lowered to 750°C, the pressure is 200 mbar, and a pure N2 atmosphere is used. TMGa is used as a Ga source to grow a channel defect generating layer (GaN layer) on the N-type semiconductor layer 3.

[0108] (6) Raising the temperature to 880°C and under a pressure of 200 mbar, three pairs of sequentially stacked InGaN layers and GaN layers are grown to obtain a channel defect amplification layer.

[0109] (7) Raise the temperature to 980°C, 200 mbar pressure, and grow a channel defect repair layer (GaN layer) in a H2 atmosphere to repair the channel pits of the channel defects until the surface is flat.

[0110] (8) A multi-quantum well light-emitting layer 5 is grown on the surface of the channel defect repair layer. The growth temperature of the GaN barrier layer is 870° C., and the growth temperature of the InGaN well layer is 790° C. The gallium source used for the InGaN well layer and the GaN barrier layer is TEGa.

[0111] (9) Raise the temperature to 1000°C and grow a P-type AlGaN electron blocking layer under a pressure of 200 mbar. Then turn off the aluminum source, maintain the same temperature and pressure as those used to grow the P-type AlGaN electron blocking layer, and continue to grow a Mg-doped P-type GaN layer, where the Mg doping concentration in the Mg-doped P-type GaN layer is 1×10 20 atoms / cm 3 , with a total thickness of 180nm.

[0112] Example 3

[0113] The present embodiment provides an LED epitaxial structure, including a substrate 1 and an epitaxial layer 100 located on the substrate 1, wherein the epitaxial layer 100 includes a buffer layer 2, an N-type semiconductor layer 3, a channel defect composite layer 4, a multi-quantum well light-emitting layer 5 and a P-type semiconductor layer 6 arranged in sequence along the epitaxial direction, and the channel defect composite layer 4 includes a channel defect generating layer, a channel defect amplifying layer and a channel defect repairing layer arranged in sequence.

[0114] The buffer layer 2 is AlGaN, and the thickness of the buffer layer 2 is 25 nm. The N-type semiconductor layer 3 includes a stacked non-doped GaN layer and a Si-doped N-type GaN layer, and the Si doping concentration in the Si-doped N-type GaN layer is 2×10 19 atoms / cm 3 The thickness of the non-doped GaN layer is 2.5 μm, and the thickness of the Si-doped N-type GaN layer is 2.5 μm. The channel defect generation layer is GaN with a thickness of 60 nm and a carbon content of 8×10 17 atoms / cm 3 , the ratio of the carbon content in the channel defect generation layer to the carbon content in the N-type semiconductor layer 3 is 3.5; the ratio of the carbon content in the channel defect generation layer to the carbon content in the multi-quantum well light-emitting layer 5 is 4. The channel defect amplification layer includes 3 pairs of stacked InGaN layers and GaN layers, the InGaN layer thickness is 15Å; the GaN layer thickness is 100Å; the channel defect repair layer is GaN, the channel defect repair layer contains impurity Si, the impurity Si originates from silane, the content of impurity Si is not less than the carbon content in the defect repair layer, and the thickness is 100nm. The multi-quantum well light-emitting layer 5 includes 10 pairs of stacked InGaN layers and GaN layers, the single layer thickness of the InGaN layer is 2nm, and the single layer thickness of the GaN layer is 9nm. The P-type semiconductor layer 6 includes stacked AlGaN and Mg-doped P-type GaN layers, and the Mg doping concentration in the Mg-doped P-type GaN layer is 2×10 20 atoms / cm 3 , the thickness of the P-type semiconductor layer 6 is 220 nm.

[0115] The method for preparing the LED epitaxial structure of this embodiment includes the following steps:

[0116] (1) An AlGaN buffer layer 2 with a thickness of 25 nm is grown on the surface of a sapphire substrate 1 at 550°C.

[0117] (2) Annealing treatment is performed in an NH3 atmosphere, and the temperature is raised to 1110°C to allow the low-temperature AlGaN to recrystallize into island-shaped seed crystals.

[0118] (3) TMGa is introduced and a three-dimensional layer with a thickness of 1 μm is grown at a pressure of 800 mbar.

[0119] (4) The temperature is raised to 1150°C and the pressure is reduced to 600 mbar, and a non-doped GaN layer with a thickness of 2.5 μm is grown. Under the conditions of a temperature of 1150°C and a pressure of 600 mbar, a Si-doped N-type GaN layer with a thickness of 2.5 μm is grown on the surface of the non-doped GaN layer to obtain an N-type semiconductor layer 3.

[0120] (5) The temperature is lowered to 750°C, the pressure is 200 mbar, and a pure N2 atmosphere is used. TMGa is used as a Ga source to grow a channel defect generating layer (GaN layer) on the N-type semiconductor layer 3.

[0121] (6) Raising the temperature to 880°C and under a pressure of 200 mbar, three pairs of sequentially stacked InGaN layers and GaN layers are grown to obtain a channel defect amplification layer.

[0122] (7) Raise the temperature to 980°C, 200 mbar pressure, and grow a channel defect repair layer (GaN layer) in a H2 atmosphere to repair the channel pits of the channel defects until the surface is flat.

[0123] (8) A multi-quantum well light-emitting layer 5 is grown on the surface of the channel defect repair layer. The growth temperature of the GaN barrier layer is 870° C., and the growth temperature of the InGaN well layer is 790° C. The gallium source used for the InGaN well layer and the GaN barrier layer is TEGa.

[0124] (9) Raise the temperature to 1000°C and grow a P-type AlGaN electron blocking layer under a pressure of 200 mbar. Then turn off the aluminum source, maintain the same temperature and pressure as those used to grow the P-type AlGaN electron blocking layer, and continue to grow a Mg-doped P-type GaN layer, where the Mg doping concentration in the Mg-doped P-type GaN layer is 1×10 20 atoms / cm 3 , with a total thickness of 220nm.

[0125] Example 4

[0126] This embodiment provides an LED epitaxial structure, which is different from the embodiment 1 in that:

[0127] The carbon content of the channel defect generation layer is 5.2×10 17 atoms / cm 3 , thickness is 15nm;

[0128] The thickness of the channel defect repairing layer is 30 nm.

[0129] Example 5

[0130] This embodiment provides an LED epitaxial structure, which is different from the embodiment 1 in that:

[0131] The carbon content of the channel defect generation layer is 7.5×10 17 atoms / cm 3 , thickness is 40nm;

[0132] The thickness of the channel defect repairing layer is 85 nm.

[0133] Example 6

[0134] This embodiment provides an LED epitaxial structure, which is different from the embodiment 1 in that:

[0135] The carbon content of the channel defect generation layer is 10×10 18 atoms / cm 3 , thickness is 100nm;

[0136] The thickness of the channel defect repairing layer is 150 nm.

[0137] Example 7

[0138] An LED device, such as Figure 2 As shown, it includes an LED epitaxial structure, a current blocking layer 7, a current spreading layer 8, an N electrode 10, a P electrode 9 and an insulating layer 11. The LED epitaxial structures are the LED epitaxial structures in Examples 1 to 6.

[0139] The current blocking layer 7 is located on the surface of the P-type semiconductor layer 6 of the LED epitaxial structure. The current spreading layer 8 covers the P-type semiconductor layer 6 and is located on the surface of the P-type semiconductor layer 6. The P electrode 9 is arranged on the current spreading layer 8 and is electrically connected to the P-type semiconductor layer 6. The N electrode 10 is arranged in the N step region and is electrically connected to the N-type semiconductor layer 3. The insulating layer 11 covers the P electrode 9 and the N electrode 10, and exposes a portion of the P electrode 9 and the N electrode 10.

[0140] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents. However, these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. An LED epitaxial structure, characterized in that: It includes a substrate and an epitaxial layer located on the substrate, wherein the epitaxial layer includes a buffer layer, an N-type semiconductor layer, a channel defect composite layer, a multi-quantum well light-emitting layer and a P-type semiconductor layer arranged in sequence along the epitaxial direction, and the channel defect composite layer includes a channel defect generating layer, a channel defect amplifying layer and a channel defect repairing layer arranged in sequence; The channel defect in the channel defect composite layer is ring-shaped; The carbon content in the channel defect generating layer is not less than 5×10 17 atoms / cm 3 ; The channel defect amplification layer includes an InGaN layer and a GaN layer, and the InGaN layer and the GaN layer are alternately stacked.

2. The LED epitaxial structure according to claim 1, characterized in that: Contains at least one of the following features (1) to (4): (1) The channel defect generating layer comprises GaN; (2) The ratio of the carbon content in the channel defect generating layer to the carbon content in the N-type semiconductor layer is greater than or equal to 2; the ratio of the carbon content in the channel defect generating layer to the carbon content in the multi-quantum well light-emitting layer is greater than or equal to 2; (3) The channel defect generating layer further contains impurity Si, and the content of the impurity Si is not less than the carbon content in the channel defect generating layer; (4) The thickness of the channel defect generating layer is 10-200 nm.

3. The LED epitaxial structure according to claim 1, characterized in that: Contains at least one of the following features (1) to (2): (1) The number of layers of the InGaN layer and the GaN layer are independently 2 to 6 layers; (2) The thickness of the InGaN layer is 15~40Å; the thickness of the GaN layer is 50~400Å.

4. The LED epitaxial structure according to claim 1, characterized in that: Contains at least one of the following features (1) to (2): (1) The channel defect repair layer includes GaN; (2) The thickness of the channel defect repair layer is 10-200 nm.

5. The LED epitaxial structure according to claim 1, characterized in that: Contains at least one of the following features (1) to (9): (1) The buffer layer includes AlGaN; (2) The thickness of the buffer layer is 15-25 nm; (3) The N-type semiconductor layer includes a stacked non-doped GaN layer and a Si-doped N-type GaN layer, wherein the Si-doped N-type GaN layer has a Si doping concentration of 2×10 19 ~5×10 19 atoms / cm 3 ; (4) The thickness of the N-type semiconductor layer is 3-8 μm; (5) The multi-quantum well light-emitting layer includes an InGaN layer and a GaN layer stacked together; (6) The thickness of the multi-quantum well light-emitting layer is 100-130 nm; (7) The P-type semiconductor layer includes a stacked AlGaN layer and a Mg-doped P-type GaN layer, wherein the Mg-doped P-type GaN layer has a Mg doping concentration of 0.8×10 20 ~2×10 20 atoms / cm 3 ; (8) The thickness of the P-type semiconductor layer is 180-220 nm (9) The ratio of the In concentration of the multi-quantum well light-emitting layer to the In concentration of the defect amplification layer is not less than 3.

6. The method for preparing an LED epitaxial structure according to any one of claims 1 to 5, characterized in that: The following steps are involved: A substrate is provided, and a buffer layer, an N-type semiconductor layer, a channel defect generating layer, a channel defect amplifying layer, a channel defect repairing layer, and a multi-quantum well light-emitting layer P-type semiconductor layer are sequentially grown on a surface of one side of the substrate along its epitaxial direction.

7. The method for preparing an LED epitaxial structure according to claim 6, characterized in that: Contains at least one of the following features (1) to (3): (1) The growth conditions of the channel defect generating layer include: using TMGa as a Ga source, a growth atmosphere of nitrogen, a growth temperature of 700-760° C., a growth pressure of 180-220 mbar, and growing a GaN layer; (2) Growth conditions of the channel defect amplification layer include: a growth temperature of 880-950° C., a growth pressure of 180-220 mbar, and alternating growth of InGaN layers and GaN layers; (3) The growth conditions of the channel defect repair layer include: a growth temperature of 980-1050° C., a growth pressure of 180-220 mbar, a growth atmosphere of hydrogen, and a GaN layer.

8. The method for preparing an LED epitaxial structure according to claim 6, characterized in that: Contains at least one of the following features (1) to (4): (1) The growth conditions of the buffer layer include: a growth temperature of 500-600°C to obtain an AlGaN layer, and then annealing treatment under ammonia conditions at a temperature of 1100-1200°C; (2) The growth conditions of the N-type semiconductor layer include: first growing a GaN layer, then growing a Si-doped N-type GaN layer, the growth temperature is 1120-1180° C., and the growth pressure is 550-650 mbar; (3) The growth conditions of the multi-quantum well light-emitting layer include: using TEGa as a gallium source, alternately growing InGaN layers and GaN layers in sequence, the growth temperature of GaN is 850-900°C, and the growth temperature of InGaN is 750-820°C; (4) The growth conditions of the P-type semiconductor layer include: sequentially growing an AlGaN layer and a Mg-doped P-type GaN layer at a growth temperature of 980-1050° C. and a growth pressure of 1800-220 mbar.

9. An LED device, characterized in that: The LED epitaxial structure comprises the LED epitaxial structure according to any one of claims 1 to 5, and a current blocking layer, a current spreading layer, an N electrode, a P electrode and an insulating layer; The current blocking layer is located on the surface of the P-type semiconductor layer of the LED epitaxial structure; The current spreading layer covers the P-type semiconductor layer and is located on the surface of the P-type semiconductor layer; The P electrode is disposed on the current spreading layer and is electrically connected to the P-type semiconductor layer; The N electrode is disposed in the N step region and is electrically connected to the N-type semiconductor layer; The insulating layer covers the P electrode and the N electrode and exposes a portion of the P electrode and the N electrode.

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