Infrared led epitaxial structure and preparation method thereof

Abstract

The application provides an infrared LED epitaxial structure and a preparation method thereof, wherein the infrared LED epitaxial structure comprises, from bottom to top, a buffer layer on a substrate, an etching stop layer, a first type semiconductor layer, a first stress change layer, an active layer, a second stress change layer and a second type semiconductor layer, wherein the first stress change layer is an In composition gradient structure layer, and the second stress change layer is an In composition fixed structure layer. By inserting the In composition gradient first stress change layer between the active layer and the first type semiconductor layer and inserting the In composition fixed second stress change layer between the active layer and the second type semiconductor layer, the ability of the active layer to confine electrons and holes can be improved, the radiation recombination probability of the electrons and holes can be enhanced, and the luminous brightness of the LED can be improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of semiconductor, in particular to an infrared LED epitaxial structure and a preparation method thereof. BACKGROUND

[0002] Light is a kind of electromagnetic wave, and its wavelength interval is from several nanometers to about one millimeter. Only a part of it is visible to human eyes, which is called visible light. The wavelength range of visible light is 380nm-780nm, and the visible light is divided into red, orange, yellow, green, cyan, blue and purple light from long to short, and the wavelength shorter than purple light is called ultraviolet light, and the wavelength longer than red light is called infrared light.

[0003] The infrared light-emitting diode (i.e. infrared LED) is made of a PN junction of a material with high infrared radiation efficiency, and a forward bias voltage is injected into the PN junction to excite infrared light. The commonly used material with high infrared radiation efficiency is gallium arsenide (GaAs). The center wavelength of the spectral power distribution of the infrared light emitted by the infrared LED is 830nm-950nm, and the half-peak bandwidth is about 40nm.

[0004] The luminous power of the infrared LED is larger than that of the visible light LED, and it is often used in the field of communication and sensor, so the driving force for the continuous growth of the demand for infrared LED comes from household appliances, safety systems and wireless communication products, such as closed-circuit television monitoring systems commonly used to enhance the safety of public places such as streets, train stations, airports and schools.

[0005] With the development of semiconductor technology, people's demand for the brightness of infrared LED is getting higher and higher, therefore, it is necessary to provide an infrared LED epitaxial structure and a preparation method thereof to improve the luminous brightness of the infrared LED. SUMMARY

[0006] The present application aims to provide an infrared LED epitaxial structure and a preparation method thereof to improve the luminous brightness of the LED.

[0007] In order to achieve the above-mentioned purpose and other related purposes, the present application provides an infrared LED epitaxial structure, which comprises, from bottom to top, a buffer layer, an etching stop layer, a first type semiconductor layer, a first stress change layer, an active layer, a second stress change layer and a second type semiconductor layer, wherein the first stress change layer is an In composition gradient structure layer, and the second stress change layer is an In composition fixed structure layer.

[0008] Optionally, in the infrared LED epitaxial structure, the In composition of the second stress change layer is higher than that of the first stress change layer.

[0009] Optionally, in the infrared LED epitaxial structure, the In composition of the first stress variation layer gradually increases along a direction from the first type semiconductor layer to the active layer.

[0010] Optionally, in the infrared LED epitaxial structure, the material of the first stress variation layer comprises In x Al 1- x As, and x ranges from 0.1 to 0.9.

[0011] Optionally, in the infrared LED epitaxial structure, the material of the second stress variation layer comprises In y Al 1- y As, and y ranges from 0.1 to 0.9.

[0012] Optionally, in the infrared LED epitaxial structure, the thickness of the first stress variation layer is 10 nm to 200 nm, and the thickness of the second stress variation layer is 10 nm to 200 nm.

[0013] Optionally, in the infrared LED epitaxial structure, the first type semiconductor layer comprises, from bottom to top, a first type ohmic contact layer, a first type current spreading layer, a first type confinement layer, and a first type spacer layer.

[0014] Optionally, in the infrared LED epitaxial structure, the second type semiconductor layer comprises, from bottom to top, a second type spacer layer, a second type confinement layer, a second type current spreading layer, and a second type ohmic contact layer.

[0015] Optionally, in the infrared LED epitaxial structure, the first type semiconductor layer is an N-type semiconductor layer, and the second type semiconductor layer is a P-type semiconductor layer.

[0016] To achieve the above object and other related objects, the present application further provides a preparation method of an infrared LED epitaxial structure, comprising the following steps:

[0017] providing a substrate;

[0018] growing, on the substrate, a buffer layer, an etching stop layer, a first type semiconductor layer, and a first stress variation layer in sequence, wherein the first stress variation layer is an In composition gradient structure layer;

[0019] growing, on the first stress variation layer, an active layer, a second stress variation layer, and a second type semiconductor layer in sequence, wherein the second stress variation layer is an In composition fixed structure layer.

[0020] Optionally, in the preparation method of the infrared LED epitaxial structure, the In component of the second stress variation layer is higher than the In component of the first stress variation layer.

[0021] Optionally, in the preparation method of the infrared LED epitaxial structure, the In component of the first stress variation layer gradually increases along a direction from the first-type semiconductor layer to the active layer.

[0022] Optionally, in the preparation method of the infrared LED epitaxial structure, the material of the first stress variation layer comprises In x Al 1-x As, and the range of x is 0.1-0.9.

[0023] Optionally, in the preparation method of the infrared LED epitaxial structure, the material of the second stress variation layer comprises In y Al 1-y As, and the range of y is 0.1-0.9.

[0024] Optionally, in the preparation method of the infrared LED epitaxial structure, the thickness of the first stress variation layer is 10-200 nm, and the thickness of the second stress variation layer is 10-200 nm.

[0025] Optionally, in the preparation method of the infrared LED epitaxial structure, the first-type semiconductor layer comprises, from bottom to top, a first-type ohmic contact layer, a first-type current spreading layer, a first-type confinement layer, and a first-type spacer layer.

[0026] Optionally, in the preparation method of the infrared LED epitaxial structure, the second-type semiconductor layer comprises, from bottom to top, a second-type spacer layer, a second-type confinement layer, a second-type current spreading layer, and a second-type ohmic contact layer.

[0027] Optionally, in the preparation method of the infrared LED epitaxial structure, the first-type semiconductor layer is an N-type semiconductor layer, and the second-type semiconductor layer is a P-type semiconductor layer.

[0028] Optionally, in the preparation method of the infrared LED epitaxial structure, the preparation process of the epitaxial structure is any one of MOCVD process, molecular beam epitaxy process, HVPE process, plasma-assisted chemical vapor deposition, and sputtering method.

[0029] Compared with the prior art, the technical scheme of the present application has the following beneficial effects:

[0030] The application inserts the first stress change layer with gradually changed In component between the active layer and the first type semiconductor layer, inserts the second stress change layer with fixed In component between the active layer and the second type semiconductor layer, changes the stress state of the active layer, makes the potential barrier of the active layer higher, improves the ability of the active layer to limit electrons and holes, enhances the radiation recombination probability of the electrons and holes, and further improves the light emission intensity and brightness. BRIEF DESCRIPTION OF DRAWINGS

[0031] Fig. 1 is a structural schematic diagram of an infrared LED epitaxial structure of an embodiment of the application;

[0032] Fig. 2 is a flowchart of a preparation method of an infrared LED epitaxial structure of an embodiment of the application;

[0033] Figs. 1-2 In the application,

[0034] 10-substrate, 20-infrared LED epitaxial structure, 201-buffer layer, 202-etching stop layer, 203-first type ohmic contact layer, 204-first type current spreading layer, 205-first type confinement layer, 206-first type spacer layer, 207-first stress change layer, 208-active layer, 209-second stress change layer, 210-second type spacer layer, 211-second type confinement layer, 212-second type current spreading layer, 213-second type ohmic contact layer. DETAILED DESCRIPTION

[0035] The infrared LED epitaxial structure and the preparation method thereof according to the application will be further described in detail below in combination with the drawings and specific embodiments. The advantages and features of the application will be more apparent according to the following description. It should be noted that the drawings are all very simplified and use non-precise proportions, which are only used to facilitate and clarify the purpose of assisting the description of the embodiments of the application.

[0036] Before the embodiments according to the application are described, the following is described in advance. First, in the present specification, only when marked as "GaInP", it represents any compound with the chemical composition ratio of the total of Ga and In to P being 1:1, and the ratio of Ga to In being arbitrary and not fixed. Only when marked as "AlGaAs", it represents any compound with the chemical composition ratio of the total of Al and Ga to As being 1:1, and the ratio of Al to Ga being arbitrary and not fixed. Only when marked as "InGaAs", it represents any compound with the chemical composition ratio of the total of Ga and In to As being 1:1, and the ratio of Ga to In being arbitrary and not fixed. In addition, only when marked as "InAlAs", it represents any compound with the chemical composition ratio of the total of Al and In to As being 1:1, and the ratio of Al to In being arbitrary and not fixed.

[0037] Referring toFig. 1 The infrared LED epitaxial structure 20 comprises, from bottom to top, a buffer layer 201, an etching stop layer 202, a first type semiconductor layer, a first stress variation layer 207, an active layer 208, a second stress variation layer 209, and a second type semiconductor layer on the substrate 10, wherein the first stress variation layer 207 is a structure layer with gradually changed In composition, and the second stress variation layer 209 is a structure layer with fixed In composition.

[0038] The first type semiconductor layer comprises, from bottom to top, a first type ohmic contact layer 203, a first type current spreading layer 204, a first type confinement layer 205, and a first type spacer layer 206.

[0039] The second type semiconductor layer comprises, from bottom to top, a second type spacer layer 210, a second type confinement layer 211, a second type current spreading layer 212, and a second type ohmic contact layer 213.

[0040] The first type semiconductor layer and the second type semiconductor layer have opposite polarities, for example, the first type semiconductor layer is an N-type semiconductor layer, and the corresponding second type semiconductor layer is a P-type semiconductor layer. Correspondingly, the N-type semiconductor layer comprises, from bottom to top, an N-type ohmic contact layer, an N-type current spreading layer, an N-type confinement layer, and an N-type spacer layer. The P-type semiconductor layer comprises, from bottom to top, a P-type spacer layer, a P-type confinement layer, a P-type current spreading layer, and a P-type ohmic contact layer.

[0041] Referring to Fig. 2 The preparation method of the infrared LED epitaxial structure 20 specifically comprises the following steps.

[0042] Step S1: providing a substrate 10;

[0043] Step S2: sequentially growing a buffer layer 201, an etching stop layer 202, a first type semiconductor layer, and a first stress variation layer 207 on the substrate 10, and the first stress variation layer 207 is a structure layer with gradually changed In composition.

[0044] Step S3: sequentially growing an active layer 208, a second stress variation layer 209, and a second type semiconductor layer on the first stress variation layer 207, and the second stress variation layer 209 is a structure layer with fixed In composition.

[0045] The preparation process of the infrared LED epitaxial structure 20 is any one of MOCVD process, molecular beam epitaxy process, HVPE process, plasma-assisted chemical vapor deposition, and sputtering method, and is preferably MOCVD process. In the following specific embodiments, MOCVD process is taken as an example for description.

[0046] In step S1, the substrate 10 can be GaAs, but is not limited thereto.

[0047] In step S2, a first-type semiconductor layer is grown on the substrate 10, and the first-type semiconductor layer can include a buffer layer 201, an etching stop layer 202, a first-type ohmic contact layer 203, a first-type current spreading layer 204, a first-type confinement layer 205, and a first-type spacer layer 206.

[0048] The buffer layer 201 minimizes the influence of surface defects of the substrate 10 on the infrared LED epitaxial structure 20, reduces defects and dislocations of the infrared LED epitaxial structure 20, and provides a fresh interface for the next growth. The material of the buffer layer 201 is preferably GaAs, but is not limited thereto. The buffer layer 201 is doped with a first-type dopant, such as an N-type dopant, which can be at least one of silicon (Si), germanium (Ge), tin (Sn), and tellurium (Te), but is not limited thereto. Further, the first-type dopant is preferably Si.

[0049] The growth of the buffer layer 201 is preferably to grow a buffer layer 201 with a thickness of 100 nm to 500 nm in the reaction chamber of the MOCVD growth furnace. For example, a buffer layer 201 with a thickness of 300 nm is grown.

[0050] After the growth of the buffer layer 201, the etching stop layer 202 is grown on the buffer layer 201. The etching stop layer 202 is mainly used to protect the structure layer grown on the substrate 10, i.e., to protect the first-type ohmic contact layer 203, when the substrate 10 is peeled off. The material of the etching stop layer 202 is preferably GaInP, but is not limited thereto. The etching stop layer 202 is doped with a first-type dopant, such as an N-type dopant, which can be at least one of silicon (Si), germanium (Ge), tin (Sn), and tellurium (Te), but is not limited thereto. Further, the first-type dopant is preferably Si.

[0051] The growth of the etching stop layer 202 is preferably to grow an etching stop layer 202 with a thickness of 100 nm to 500 nm in the reaction chamber of the MOCVD growth furnace. For example, an etching stop layer 202 with a thickness of 200 nm is grown.

[0052] After the growth of the etching stop layer 202, the first-type ohmic contact layer 203 is grown on the etching stop layer 202. The material of the first-type ohmic contact layer 203 is preferably GaAs, but is not limited thereto. The first-type ohmic contact layer 203 is doped with a first-type dopant, such as an N-type dopant, which can be at least one of silicon (Si), germanium (Ge), tin (Sn), and tellurium (Te), but is not limited thereto. Further, the first-type dopant is preferably Si.

[0053] The growth of the first-type ohmic contact layer 203 is preferably growing a first-type ohmic contact layer 203 with a thickness of 50nm to 300nm in the reaction chamber of a MOCVD growth furnace. For example, a first-type ohmic contact layer 203 with a thickness of 200nm is grown.

[0054] After the growth of the first-type ohmic contact layer 203, a first-type current spreading layer 204 is grown on the first-type ohmic contact layer 203. The main function of the first-type current spreading layer 204 is current spreading. The material of the first-type current spreading layer 204 is preferably AlGaAs, but is not limited thereto. The first-type current spreading layer 204 is doped with a first-type dopant, such as an N-type dopant, which can be at least one of silicon (Si), germanium (Ge), tin (Sn), and tellurium (Te), but is not limited thereto. Further, the first-type dopant is preferably Si.

[0055] The growth of the first-type current spreading layer 204 is preferably growing a first-type current spreading layer 204 with a thickness of 5000nm to 10000nm in the reaction chamber of a MOCVD growth furnace. For example, a first-type current spreading layer 204 with a thickness of 5000nm is grown.

[0056] After the growth of the first-type current spreading layer 204, the first-type confinement layer 205 is grown on the first-type current spreading layer 204. The first-type confinement layer 205 is used to provide electrons and to confine the minority carriers from overflowing the active layer 208, thereby improving the recombination light emission efficiency. The material of the first-type confinement layer 205 is preferably AlGaAs, but is not limited thereto. The first-type confinement layer 205 is doped with a first-type dopant, such as an N-type dopant, which can be at least one of silicon (Si), germanium (Ge), tin (Sn), and tellurium (Te), but is not limited thereto. Further, the first-type dopant is preferably Si.

[0057] The growth of the first-type confinement layer 205 is preferably growing a first-type confinement layer 205 with a thickness of 300nm to 600nm in the reaction chamber of a MOCVD growth furnace. For example, a first-type confinement layer 205 with a thickness of 400nm is grown.

[0058] After the growth of the first-type confinement layer 205, the first-type spacer layer 206 is grown on the first-type confinement layer 205. The material of the first-type spacer layer 206 is preferably AlGaAs, but is not limited thereto. The first-type spacer layer 206 is an undoped layer, i.e., the first-type spacer layer 206 is not doped with any element.

[0059] The growth of the first type spacer layer 206 is preferably 200-500 nm thick in the reaction chamber of the MOCVD growth furnace. For example, the first type spacer layer 206 is grown to be 200 nm thick.

[0060] After the growth of the first type spacer layer 206, a first stress change layer 207 is grown on the first type spacer layer 206. The material of the first stress change layer 207 is preferably In x Al 1-x As, and the range of x is preferably 0.1-0.9. The first stress change layer 207 is a structure layer with gradually changing In composition, and the way of gradually changing In composition is:

[0061] from low In composition to high In composition, that is, the In composition gradually increases along the growth direction of the first stress change layer 207 (from the first type spacer layer 206 to the active layer 208). For example, the In composition gradually increases from 0.3 to 0.6 along the growth direction of the first stress change layer 207. The change interval of the In composition of the first stress change layer 207 is any interval between 0.1 and 0.9, and further, the change interval is preferably set according to the specific epitaxial structure, which specifically satisfies that the lattice constant of the first stress change layer 207 is greater than that of the quantum well of the active layer 208. The composition of In and Ga in the quantum well determines the wavelength of light emission, and the composition of the quantum well is fixed according to the wavelength requirement, and the lattice constant of the quantum well is obtained, and then the composition of the first stress change layer 207 is adjusted to make the lattice constant greater than that of the quantum well. Since the lattice constant of the first stress change layer 207 is greater than that of the quantum well, the quantum well is subjected to tensile strain, the quantum well is widened, the quantum barrier is squeezed, and the potential barrier of the quantum barrier is increased, thereby improving the ability of the active layer to limit electrons and holes, increasing the probability of electron-hole recombination, and thereby improving the luminous brightness.

[0062] For the InAlAs material of the first stress change layer 207, the higher the In composition, the greater the lattice constant, the greater the lattice mismatch with the first type spacer layer 206, and the more defects are generated. Therefore, the first stress change layer 207 needs to gradually increase from a lower In composition to achieve the purpose of buffering.

[0063] The growth of the first stress change layer 207 is preferably 10-200 nm thick in the reaction chamber of the MOCVD growth furnace. For example, the first stress change layer 207 is grown to be 100 nm thick.

[0064] In step S3, after growing the first stress change layer 207, the active layer 208 is grown on the first stress change layer 207. The active layer 208 is mainly used as a light emitting layer. The active layer 208 is preferably a multi-quantum well structure, i.e. the active layer 208 is preferably a periodic structure composed of quantum wells and quantum barriers, and the number of periods of the active layer 208 is preferably 6-20. For example, the number of periods of the active layer 208 is 10. The material of the quantum well is preferably InGaAs, but is not limited thereto. The material of the quantum barrier is preferably AlGaAs, but is not limited thereto. The total thickness of the active layer 208 is preferably 100-400 nm, and the light emitting wavelength of the active layer 208 is preferably 800-1000 nm.

[0065] The growth of the active layer 208 is preferably growth of the active layer 208 for 6-20 periods in the reaction chamber of a MOCVD growth furnace. For example, the active layer 208 is grown for 10 periods, and the thickness of the active layer for 10 periods is about 200 nm.

[0066] After growing the active layer 208, a second stress change layer 209 is grown on the active layer 208. The material of the second stress change layer 209 is preferably In y Al 1-y As, and the range of y is preferably 0.1-0.9. For example, the material of the second stress change layer 209 is In 0.7 Al 0.3 As. The second stress change layer 209 is a structure layer with a fixed In component, and the In component of the second stress change layer 209 is higher than that of the first stress change layer 207, i.e. y>x. The In component of the second stress change layer 209 can be set according to the specific epitaxial structure, and specifically satisfies that the lattice constant of the second stress change layer 209 is greater than that of the quantum well of the active layer 208. The components of In and Ga in the quantum well determine the light emitting wavelength, and the components of the quantum well are fixed according to the wavelength requirement, the lattice constant of the quantum well is obtained, and then the components of the second stress change layer 209 are regulated so that the lattice constant is greater than that of the quantum well. Since the lattice constant of the second stress change layer 209 is greater than that of the quantum well, tensile strain is applied to the quantum well, the quantum well is widened, the quantum barrier is squeezed, and then the potential barrier of the quantum barrier is increased, the ability to limit electrons and holes in the active layer is improved, the recombination probability of electrons and holes is improved, and then the light emitting brightness is improved.

[0067] The material of the second stress change layer 209 is preferably InAlAs, and the In component of the second stress change layer 209 is higher than that of the first stress change layer 207. For InAlAs material, the higher the In component, the larger the lattice constant, and the larger the lattice mismatch with the active layer 208 and the second-type spacer layer 210, and the more defects are generated. Since a large stress is generated in the active layer 208, the crystal quality is poor, and these defects can release the excess stress in the active layer 208, so the second stress change layer 209 is designed to have a high In component structure to make the second stress change layer 209 have a large lattice mismatch with the active layer 208 and the second-type semiconductor layer, generate more defects, and more effectively release the excess stress in the active layer 208. Moreover, the materials of the structure layers of the second-type semiconductor layer grown subsequently in the embodiment are preferably the same, for example, AlGaAs, which is a matching structure. These defects will gradually disappear in the subsequent growth, so that the overall crystal quality is still good.

[0068] The growth of the second stress change layer 209 is preferably to grow a second stress change layer 209 with a thickness of 10 nm to 200 nm in the reaction chamber of the MOCVD growth furnace. For example, a second stress change layer 209 with a thickness of 50 nm is grown.

[0069] After the growth of the second stress change layer 209, the second-type semiconductor layer is grown on the second stress change layer 209, and the second-type semiconductor layer comprises, from bottom to top, a second-type spacer layer 210, a second-type confinement layer 211, a second-type current spreading layer 212, and a second-type ohmic contact layer 213.

[0070] Therefore, after the growth of the second stress change layer 209, the second-type spacer layer 210 is grown on the second stress change layer 209. The material of the second-type spacer layer 210 is preferably the same as that of the first-type spacer layer 206, that is, the material of the second-type spacer layer 210 is also preferably AlGaAs, but is not limited thereto. The second-type spacer layer 210 is an undoped layer, that is, no element is doped in the second-type spacer layer 210.

[0071] The growth of the second-type spacer layer 210 is preferably to grow a second-type spacer layer 210 with a thickness of 200 nm to 500 nm in the reaction chamber of the MOCVD growth furnace. For example, a second-type spacer layer 210 with a thickness of 200 nm is grown.

[0072] After the growth of the second-type space layer 210, the second-type confinement layer 211 is grown on the second-type space layer 210. The second-type confinement layer 211 is used to provide holes. Moreover, the first-type confinement layer 205 and the second-type confinement layer 211 as confinement layers have two main functions, one is to confine the minority carriers from overflowing the active layer 208 to improve the light emitting efficiency, and the other is to serve as an important window to make the photons emitted by the active layer 208 pass through the confinement layer easily to improve the light emitting efficiency of the LED.

[0073] The material of the second-type confinement layer 211 is preferably AlGaAs, but is not limited thereto. The second-type confinement layer 211 is doped with a second-type dopant, for example, a p-type dopant, which can be at least one of magnesium (Mg), zinc (Zn), cadmium (Cd), beryllium (Be), and manganese (Mn), but is not limited thereto. Further, the second-type dopant is preferably Mg.

[0074] The growth of the second-type confinement layer 211 is preferably to grow the second-type confinement layer 211 having a thickness of 300 nm to 600 nm in the reaction chamber of the MOCVD growth furnace. For example, the second-type confinement layer 211 having a thickness of 400 nm is grown.

[0075] After the growth of the second-type confinement layer 211, the second-type current spreading layer 212 is grown on the second-type confinement layer 211. The material of the second-type current spreading layer 212 is preferably AlGaAs, but is not limited thereto. The second-type current spreading layer 212 is doped with a second-type dopant, for example, a p-type dopant, which can be at least one of magnesium (Mg), zinc (Zn), cadmium (Cd), beryllium (Be), and manganese (Mn), but is not limited thereto. Further, the second-type dopant is preferably Mg.

[0076] The growth of the second-type current spreading layer 212 is preferably to grow the second-type current spreading layer 212 having a thickness of 400 nm to 1000 nm in the reaction chamber of the MOCVD growth furnace. For example, the second-type current spreading layer 212 having a thickness of 600 nm is grown.

[0077] After the growth of the second-type current spreading layer 212, the second-type ohmic contact layer 213 is grown on the second-type current spreading layer 212. The second-type ohmic contact layer 213 is used to form an ohmic contact with a metal electrode. The material of the second-type ohmic contact layer 213 is preferably GaP, but is not limited thereto. The second-type ohmic contact layer 213 can be doped with C (carbon).

[0078] The growth of the second-type ohmic contact layer 213 is preferably growth of a second-type ohmic contact layer 213 with a thickness of 50 nm to 300 nm in the reaction chamber of the MOCVD growth furnace. For example, a second-type ohmic contact layer 213 with a thickness of 120 nm is grown.

[0079] The first stress change layer with gradually changed In composition is inserted between the active layer and the first-type semiconductor layer, and the second stress change layer with fixed In composition is inserted between the active layer and the second-type semiconductor layer, so that the stress state of the active layer is changed, the potential barrier of the active layer is increased, the ability of the active layer to confine electrons and holes is improved, the radiation recombination probability of the electrons and holes is enhanced, and the luminous intensity and brightness are improved.

[0080] In addition, it can be understood that, although the present application has been disclosed with the preferred embodiments as above, the above embodiments are not intended to limit the present application. For any person skilled in the art, many possible changes and modifications or equivalent embodiments of the above disclosed technical content can be made to the technical solution of the present application without departing from the scope of the technical solution of the present application. Therefore, any simple modification, equivalent change and modification of the above embodiments made according to the technical essence of the present application without departing from the content of the technical solution of the present application, are still within the scope of protection of the technical solution of the present application.

[0081] It is also to be understood that the application is not limited to the particular methodology, compounds, materials, manufacturing techniques, uses and applications described herein, which can vary. It is also to be understood that the terminology used herein is used for the purpose of describing particular embodiments only, and is not intended to be limiting, since the scope of the present application will be limited only by the appended claims. It must be noted that as used herein and in the appended claims, the singular forms "a", "an" and "the" include plural references unless the context clearly dictates otherwise. Thus, for example, reference to "a step" is a reference to one or more steps and can include sub-steps. All conjunctions used herein are to be understood in the widest possible context, i.e., conjunctive and disjunctive. Thus, for example, "or" should be understood to have the definition of a logical "or" rather than that of a logical "exclusive or" unless the context clearly dictates otherwise. Structures described herein are to be understood to refer to functional equivalents as well. Language that can be construed to be relative is to be interpreted in accordance with the context in which it is used.

Claims

1. An infrared LED epitaxial structure, characterized in that, From bottom to top, sequentially include: buffer layer on the substrate, etching stop layer, first type semiconductor layer, first stress change layer, active layer, second stress change layer and second type semiconductor layer, wherein, the first stress change layer is In component gradually changing structure layer, the second stress change layer is In component fixed structure layer, the In component of the second stress change layer is higher than the In component of the first stress change layer, the lattice constant of the first stress change layer and the second stress change layer is greater than the lattice constant of the quantum well of the active layer.

2. The infrared LED epitaxial structure of claim 1, wherein, The In component gradually changing mode in the first stress change layer is gradually increasing along the direction of the first type semiconductor layer pointing to the active layer.

3. The infrared LED epitaxial structure of claim 1, wherein, The material of the first stress change layer includes In x Al 1-x As, and x ranges from 0.1 to 0.

9.

4. The infrared LED epitaxial structure of claim 1, wherein, The material of the second stress change layer includes In y Al 1-y As, and y ranges from 0.1 to 0.

9.

5. The infrared LED epitaxial structure of claim 1, wherein, The thickness of the first stress change layer is 10nm-200nm; the thickness of the second stress change layer is 10nm-200nm.

6. The infrared LED epitaxial structure of claim 1, wherein, The first type semiconductor layer sequentially includes: first type ohmic contact layer, first type current expansion layer, first type restriction layer and first type space layer from bottom to top.

7. The infrared LED epitaxial structure of claim 1, wherein, The second type semiconductor layer sequentially includes: second type space layer, second type restriction layer, second type current expansion layer and second type ohmic contact layer from bottom to top.

8. The infrared LED epitaxial structure of claim 1, wherein, The first type semiconductor layer is N type semiconductor layer, and the second type semiconductor layer is P type semiconductor layer.

9. A method of fabricating an infrared LED epitaxial structure, characterized in that, The method comprises the following steps: Providing a substrate; Growing buffer layer, etching stop layer, first type semiconductor layer and first stress change layer on the substrate in sequence, and the first stress change layer is In component gradually changing structure layer; Growing active layer, second stress change layer and second type semiconductor layer on the first stress change layer in sequence, and the second stress change layer is In component fixed structure layer, the In component of the second stress change layer is higher than the In component of the first stress change layer, the lattice constant of the first stress change layer and the second stress change layer is greater than the lattice constant of the quantum well of the active layer.

10. The method of claim 9, wherein the epitaxial structure is an infrared LED epitaxial structure. The In component gradually changing mode in the first stress change layer is gradually increasing along the direction of the first type semiconductor layer pointing to the active layer.

11. The method of claim 9, wherein the epitaxial structure is an infrared LED epitaxial structure. The material of the first stress change layer includes In x Al 1-x As, and x ranges from 0.1 to 0.

9.

12. The method of claim 9, wherein the epitaxial structure is an infrared LED epitaxial structure. The material of the second stress change layer includes In y Al 1-y As, and y ranges from 0.1 to 0.

9.

13. The method of claim 9, wherein the epitaxial structure is an infrared LED epitaxial structure. The thickness of the first stress change layer is 10nm-200nm; the thickness of the second stress change layer is 10nm-200nm.

14. The method of claim 9, wherein the epitaxial structure is an infrared LED epitaxial structure. The first type semiconductor layer sequentially includes: first type ohmic contact layer, first type current expansion layer, first type restriction layer and first type space layer from bottom to top.

15. The method of claim 9, wherein the method further comprises: The second type semiconductor layer sequentially includes: second type space layer, second type restriction layer, second type current expansion layer and second type ohmic contact layer from bottom to top.

16. The method of claim 9, wherein the epitaxial structure is an infrared LED epitaxial structure. The first type semiconductor layer is N type semiconductor layer, and the second type semiconductor layer is P type semiconductor layer.

17. The method of claim 9, wherein the method further comprises: The preparation process of the epitaxial structure is any one of MOCVD process, molecular beam epitaxy process, HVPE process, plasma assisted chemical vapor deposition and sputtering method.

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