Light emitting diode epitaxial structure and light emitting diode

Abstract

The invention relates to the technical field of semiconductor devices, in particular to a light-emitting diode epitaxial structure and a light-emitting diode. The light-emitting diode epitaxial structure comprises a substrate, and an N-type semiconductor layer, a stress release layer, a multi-quantum well layer and a P-type semiconductor layer which are sequentially arranged on the substrate, the In element concentration curve comprises an In monotone rising curve close to the N-type semiconductor layer and an In oscillation curve; in the C element concentration curve, the C element doping concentration at the position corresponding to the In oscillation curve is lower than the C element doping concentration at the position corresponding to the In monotonic rising curve; the P-type semiconductor layer at least comprises a first P-type semiconductor sub-layer and a second P-type semiconductor sub-layer in sequence, and the C element content in the first P-type semiconductor sub-layer is higher than that in the second P-type semiconductor sub-layer. According to the light emitting diode epitaxial structure, the problems that a traditional InGaN / GaN stress release layer is poor in growth quality and prone to electric leakage are solved, and the light emitting efficiency of a product is greatly improved.

Description

[0001] This invention application is a divisional application with application number 2022113029661, application date October 24, 2022, and invention name “Light-emitting diode epitaxial structure and light-emitting diode”. Technical Field

[0002] The present invention relates to the technical field of semiconductor devices, and in particular to a light emitting diode epitaxial structure and a light emitting diode. Background Art

[0003] Light Emitting Diode (LED) is a light-emitting device that can efficiently convert electrical energy into light energy. It releases energy and emits light through the recombination of electrons and holes. It is widely used in lighting, display and other fields. As the core part of LED, epitaxial wafers have received much attention and research. The structure of the currently commonly used epitaxial wafers includes: substrate, N-type GaN semiconductor layer, In-containing multi-quantum well layer and P-type GaN semiconductor layer.

[0004] The In-containing multi-quantum well layer usually includes three groups of multiple barrier layers and multiple well layers stacked alternately, specifically including a low-In multi-quantum well layer close to the N-type GaN semiconductor layer, a high-In multi-quantum well layer close to the P-type GaN semiconductor layer, and a medium-In multi-quantum well layer located between the low-In multi-quantum well layer and the high-In multi-quantum well layer. The low-In multi-quantum well layer is used as a stress release layer, and the stress in the epitaxial structure is relieved by using the good lattice matching characteristics of the InGaN shallow well layer with a low In component and the GaN shallow barrier layer; the medium-In multi-quantum well layer is used as the second transition layer, connecting the low-In multi-quantum well layer and the high-In multi-quantum well layer to gradually relieve the stress; the high-In multi-quantum well layer is a light-emitting layer.

[0005] The above-mentioned configuration of the In-containing multi-quantum well layer has the following problems:

[0006] (1) The lattice mismatch between the low-In content InGaN shallow well layer and the GaN shallow barrier layer is smaller than that between the high-In content InGaN well layer and the GaN barrier layer; however, the lattice mismatch between the InGaN / GaN heterostructure cannot be completely eliminated; the stress generated by the lattice mismatch leads to poor material growth quality;

[0007] (2) In doping GaN will introduce V-type defects. Although the existence of V-type defects is beneficial to hole transport, the introduction of V-type defects before the multi-quantum well light-emitting layer begins to grow can easily cause holes to be transported to the bottom layer, thereby causing leakage and affecting the brightness of the light.

[0008] In view of this, the present invention is proposed. Summary of the invention

[0009] One object of the present invention is to provide a light emitting diode epitaxial structure to solve the technical problems existing in the prior art such as the easy leakage of the InGaN / GaN stress release layer and the low light emitting efficiency.

[0010] Another object of the present invention is to provide a light emitting diode.

[0011] In order to achieve the above-mentioned purpose of the present invention, the following technical solutions are particularly adopted:

[0012] A light emitting diode epitaxial structure, comprising:

[0013] A substrate, and an N-type semiconductor layer, a stress release layer, a multi-quantum well layer and a P-type semiconductor layer sequentially arranged on the substrate;

[0014] In the direction from the N-type semiconductor layer to the P-type semiconductor layer, the distribution curves of the doping concentrations of the C element and the In element of the stress release layer and the multi-quantum well layer are respectively a C element concentration curve and an In element concentration curve;

[0015] The In element concentration curve includes an In monotonically rising curve close to the N-type semiconductor layer and an In oscillation curve close to the P-type semiconductor layer connected to the top of the In monotonically rising curve;

[0016] In the C element concentration curve, the C element doping concentration at a position corresponding to the In oscillation curve is lower than the C element doping concentration at a position corresponding to the In monotonically rising curve;

[0017] In the direction from the N-type semiconductor layer to the P-type semiconductor layer, the P-type semiconductor layer at least includes a first P-type semiconductor sublayer and a second P-type semiconductor sublayer in sequence, and the C element content in the first P-type semiconductor sublayer is higher than the C element content in the second P-type semiconductor sublayer.

[0018] The light-emitting diode epitaxial structure of the present invention adopts a stress-modulated GaN structure to replace the InGaN / GaN structure, and has no stress caused by lattice mismatch between heterogeneous structures, so that the material growth quality is significantly improved; and the In content in the stress release layer is low, so that the V-type defects near the N-type semiconductor are greatly reduced, thereby reducing the holes transmitted to the bottom layer through the V-type defects and reducing leakage; thus, the problems of poor growth quality and easy leakage of the traditional InGaN / GaN stress release layer are improved, and the luminous efficiency of the product is greatly improved.

[0019] In a specific embodiment of the present invention, the ratio of the highest content of the C element in the first P-type semiconductor sublayer to the lowest content of the C element in the second P-type semiconductor sublayer is ≥3, and further is 3.5-5.

[0020] In a specific embodiment of the present invention, the C element content in the first P-type semiconductor sublayer and the C element content in the second P-type semiconductor sublayer are both higher than the C element content in the multi-quantum well layer.

[0021] In a specific embodiment of the present invention, both the first P-type semiconductor sublayer and the second P-type semiconductor sublayer are doped with In element.

[0022] In a specific embodiment of the present invention, the C element concentration curve is approximately in the shape of a figure "X", including a first C smooth curve close to the N-type semiconductor layer, a second C smooth curve close to the P-type semiconductor layer, and a third C smooth curve located between the first C smooth curve and the second C smooth curve; the C element doping concentration corresponding to the third C smooth curve is higher than the C element doping concentration corresponding to the first C smooth curve and the second C smooth curve.

[0023] In a specific implementation manner of the present invention, the In oscillation curve corresponds to the second C smooth curve; the In monotonically rising curve corresponds to a portion of the third C smooth curve.

[0024] In a specific embodiment of the present invention, the C element doping concentration corresponding to the first C smooth curve is higher than the C element doping concentration corresponding to the second C smooth curve. Alternatively, the C element doping concentration corresponding to the second C smooth curve is between the C element doping concentrations corresponding to the first C smooth curve and the third C smooth curve.

[0025] In a specific embodiment of the present invention, the distribution curve of the doping concentration of the C element in the P-type semiconductor layer has at least one peak and one valley.

[0026] In a specific embodiment of the present invention, a distribution curve of the doping concentration of the In element in the P-type semiconductor layer has at least two peaks.

[0027] In a specific embodiment of the present invention, a direction from the substrate to the P-type semiconductor layer is defined as a first direction, and along the first direction, the third C smooth curve presents a distribution trend of high at both ends and low in the middle;

[0028] Alternatively, along the first direction, the third C smooth curve presents a distribution trend of low ends and high middle;

[0029] Alternatively, along the first direction, the third C smooth curve presents a gradually decreasing distribution trend;

[0030] Alternatively, along the first direction, the third C smooth curve presents a gradually increasing distribution trend;

[0031] Alternatively, along the first direction, the third C smooth curve presents a fluctuating distribution trend; the fluctuation includes at least one trough.

[0032] In a specific embodiment of the present invention, in the direction from the N-type semiconductor layer to the P-type semiconductor layer, the distribution curve of the doping concentration of n-type impurities in the stress release layer and the multi-quantum well layer is an n-type impurity concentration curve; the contour change trend of the n-type impurity concentration curve is roughly the same as that of the C element concentration curve.

[0033] In a specific embodiment of the present invention, the n-type impurity includes Si element.

[0034] In a specific embodiment of the present invention, the n-type impurity concentration curve includes a first n smooth curve close to the N-type semiconductor layer, a second n smooth curve close to the P-type semiconductor layer, and a third n smooth curve located between the first n smooth curve and the second n smooth curve; the n-type impurity doping concentration corresponding to the third n smooth curve is higher than the n-type impurity doping concentration corresponding to the first n smooth curve and the second n smooth curve.

[0035] In a specific embodiment of the present invention, a direction from the substrate to the P-type semiconductor layer is defined as a first direction, and along the first direction, the third n smooth curve profile presents a distribution trend of being high at both ends and low in the middle;

[0036] Alternatively, along the first direction, the third n smooth curve profiles present a gradually decreasing distribution trend;

[0037] Alternatively, along the first direction, the third n smooth curve profiles present a gradually increasing distribution trend;

[0038] Alternatively, along the first direction, the third n smooth curve profiles present a fluctuating distribution trend; the fluctuation includes at least one trough.

[0039] In a specific implementation of the present invention, there is a C monotonically rising curve between the first C smooth curve and the third C smooth curve, and there is a C monotonically falling curve between the third C smooth curve and the second C smooth curve.

[0040] In a specific embodiment of the present invention, the In oscillation curve consists of a first oscillation curve and a second oscillation curve; the amplitudes of the first oscillation curve and the second oscillation curve are different.

[0041] In a specific embodiment of the present invention, the In oscillation curve corresponds to the second C smooth curve, and the C element doping concentration corresponding to the second C smooth curve is between the C element doping concentrations corresponding to the first C smooth curve and the third C smooth curve.

[0042] In a specific embodiment of the present invention, the In oscillation curve corresponds to the multi-quantum well layer, wherein the concentration of In is greater than 5×10 18 atoms / cm 3 .

[0043] In a specific embodiment of the present invention, the thickness of the multi-quantum well layer is 150-280 nm.

[0044] In a specific embodiment of the present invention, the multi-quantum well layer includes a first sublayer and a second sublayer; the first sublayer includes at least one group of first barrier layers and first well layers alternately stacked, and the second sublayer includes at least one group of second barrier layers and second well layers alternately stacked.

[0045] In a specific embodiment of the present invention, the first oscillation curve corresponds to the first sub-layer, and the second oscillation curve corresponds to the second sub-layer.

[0046] In a specific embodiment of the present invention, the first C smooth curve and the third C smooth curve correspond to the stress release layer; the thickness of the stress release layer is 150 to 600 nm;

[0047] and / or,

[0048] In the third C smooth curve, the highest doping concentration of C element is 1×10 17 ~1×10 18 atoms / cm 3 .

[0049] In a specific embodiment of the present invention, in the third n smooth curve, the doping concentration of n-type impurities is 5×10 17 ~5×10 18 atoms / cm 3 .

[0050] The present invention also provides a light emitting diode, comprising any one of the light emitting diode epitaxial structures described above.

[0051] Compared with the prior art, the present invention has the following beneficial effects:

[0052] (1) The light-emitting diode epitaxial structure of the present invention adopts a stress-modulated GaN structure to replace the InGaN / GaN structure, and there is no stress caused by lattice mismatch between heterogeneous structures, so the material growth quality is significantly improved;

[0053] (2) In the epitaxial structure of the light-emitting diode of the present invention, the In content in the stress release layer is low, which greatly reduces the V-type defects near the N-type semiconductor, thereby reducing the holes transmitted to the bottom layer through the V-type defects and reducing leakage; thereby improving the poor growth quality and easy leakage of the traditional InGaN / GaN stress release layer, and greatly improving the luminous efficiency of the product. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] 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.

[0055] Figure 1 A schematic diagram of the epitaxial structure of a light emitting diode provided in an embodiment of the present invention;

[0056] Figure 2 A SIMS image of a light emitting diode epitaxial structure provided by an optional embodiment of the present invention;

[0057] Figure 3 A SIMS image of a light emitting diode epitaxial structure provided by another optional embodiment of the present invention;

[0058] Figure 4 This is a schematic diagram of the light emitting diode structure provided by the present invention.

[0059] Reference numerals:

[0060] 10-substrate; 20-buffer layer; 30-N-type semiconductor layer;

[0061] 40-stress release layer; 50-multi-quantum well layer; 60-electron blocking layer;

[0062] 70 - P-type semiconductor layer; 51 - first sublayer; 52 - second sublayer. DETAILED DESCRIPTION

[0063] The technical scheme of the present invention will be clearly and completely described below in conjunction with the accompanying drawings and specific embodiments, but it will be understood by those skilled in the art that the following described embodiments are part of embodiments of the present invention, rather than all embodiments, and are only used to illustrate the present invention, and should not be considered as limiting the scope of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative work are within the scope of protection of the present invention. If specific conditions are not specified in the embodiments, they are carried out according to normal conditions or conditions recommended by the manufacturer. If the manufacturer is not specified in the reagents or instruments used, they are all conventional products that can be purchased commercially.

[0064] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0065] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0066] In the existing LED structure, the InGaN / GaN stress release layer will cause leakage, low light efficiency and other problems due to lattice mismatch and V-shaped defects. The light-emitting diode epitaxial structure of the present invention adopts a stress-modulated GaN structure to replace the InGaN / GaN structure, without the stress of lattice mismatch between heterogeneous structures, and the material growth quality is significantly improved; and V-shaped defects and leakage are greatly reduced, improving the poor growth quality and easy leakage of the traditional InGaN / GaN stress release layer, and greatly improving the luminous efficiency of the product.

[0067] The embodiments of the present invention provide a light emitting diode epitaxial structure and a light emitting diode, which are described below through embodiments.

[0068] Example 1

[0069] Figure 1This is a schematic diagram of the epitaxial structure of a light emitting diode provided in an embodiment of the present invention. Figure 2 A SIMS image of a light emitting diode epitaxial structure provided by an optional embodiment of the present invention; Figure 3 This is a SIMS image of a light emitting diode epitaxial structure provided by another optional embodiment of the present invention. Figure 1 to Figure 3 As shown, the light emitting diode epitaxial structure includes:

[0070] A substrate 10, and a buffer layer 20, an N-type semiconductor layer 30, a stress release layer 40, a multi-quantum well layer 50, an electron blocking layer 60 and a P-type semiconductor layer 70 sequentially disposed on the substrate 10;

[0071] In the direction from the N-type semiconductor layer 30 to the P-type semiconductor layer 70 , the distribution curves of the doping concentrations of the C element and the In element of the stress release layer 40 and the multi-quantum well layer 50 are respectively the C element concentration curve and the In element concentration curve;

[0072] The In element concentration curve includes an In monotonically rising curve close to the N-type semiconductor layer 30 and an In oscillation curve close to the P-type semiconductor layer 70 connected to the top of the In monotonically rising curve;

[0073] In the C element concentration curve, the C element doping concentration at a position corresponding to the In oscillation curve is lower than the C element doping concentration at a position corresponding to the In monotonically rising curve;

[0074] The distribution curve of the doping concentration of the C element in the P-type semiconductor layer has at least one peak and one valley;

[0075] The distribution curve of the doping concentration of the In element in the P-type semiconductor layer has at least two peaks;

[0076] In the direction from the N-type semiconductor layer 30 to the P-type semiconductor layer 70, the P-type semiconductor layer 70 at least includes a first P-type semiconductor sublayer and a second P-type semiconductor sublayer in sequence, and the C content in the first P-type semiconductor sublayer is higher than the C content in the second P-type semiconductor sublayer. For the light-emitting diode epitaxial structure containing V-type defects, a first P-type semiconductor sublayer with a high C content is arranged on the side of the P-type semiconductor layer 70 close to the multi-quantum well layer 50, so that the material impedance at this position is increased, and holes are blocked when entering the quantum well, and tend to select relatively low-resistance V-type defects for downward conduction, which is conducive to improving the hole injection efficiency, thereby improving the light efficiency; the arrangement of the second P-type semiconductor sublayer with a low C content can reduce defects, reduce the restriction of defects on holes, increase the number of effective holes, and further improve the light efficiency.

[0077] The In monotonic rising curve means that the In doping concentration in the corresponding epitaxial structure increases monotonically in the set direction; in the monotonic increase here, the In doping concentration is allowed to fluctuate, and it is generally carried out in an increasing manner. The In oscillation curve means that in the set direction, the In doping concentration in the corresponding epitaxial structure fluctuates up and down with a certain period (or non-period).

[0078] In a specific embodiment of the present invention, the ratio of the maximum content of the C element in the first P-type semiconductor sublayer to the minimum content of the C element in the second P-type semiconductor sublayer is ≥3, and further is 3.5 to 5, for example, it can be 3.5, 4, 4.5, 5 or a range consisting of any two of them.

[0079] In a specific embodiment of the present invention, the C element content in the first P-type semiconductor sublayer and the C element content in the second P-type semiconductor sublayer are both higher than the C element content in the multi-quantum well layer.

[0080] In a specific embodiment of the present invention, both the first P-type semiconductor sublayer and the second P-type semiconductor sublayer are doped with In element. The doping of In element is more conducive to cooperating with other elements and exerting the effect of reducing lattice stress.

[0081] In an embodiment of the present invention, as an optional embodiment, the C element concentration curve is approximately in the shape of a figure "X", including a first C smooth curve close to the N-type semiconductor layer, a second C smooth curve close to the P-type semiconductor layer, and a third C smooth curve located between the first C smooth curve and the second C smooth curve; the C element doping concentration corresponding to the third C smooth curve is higher than the C element doping concentration corresponding to the first C smooth curve and the second C smooth curve.

[0082] The "smooth curve" in the present invention is not a straight line, but allows for smaller fluctuations, such as a fluctuation range within 40%.

[0083] In an embodiment of the present invention, as an optional embodiment, the In oscillation curve corresponds to the second C smooth curve; the In monotonic rising curve corresponds to part of the third C smooth curve. Specifically, the In oscillation curve and the second C smooth curve correspond to the same position of the epitaxial structure, and the In monotonic rising curve and part of the third equilibrium curve correspond to the same position of the epitaxial structure.

[0084] In an embodiment of the present invention, as an optional embodiment, the C element doping concentration corresponding to the first C smooth curve is higher than the C element doping concentration corresponding to the second C smooth curve. Alternatively, in another optional embodiment, the C element doping concentration corresponding to the first C smooth curve is lower than the C element doping concentration corresponding to the second C smooth curve; the C element doping concentration corresponding to the second C smooth curve is lower than the C element doping concentration corresponding to the first C smooth curve.

[0085] In an embodiment of the present invention, as an optional embodiment, a direction from the substrate 10 to the P-type semiconductor layer 70 is defined as a first direction, and along the first direction, the third C smooth curve presents a distribution trend of high at both ends and low in the middle;

[0086] Alternatively, along the first direction, the third C smooth curve presents a distribution trend of low ends and high middle;

[0087] Alternatively, along the first direction, the third C smooth curve presents a gradually decreasing distribution trend;

[0088] Alternatively, along the first direction, the third C smooth curve presents a gradually increasing distribution trend;

[0089] Alternatively, along the first direction, the third C smooth curve presents a fluctuating distribution trend; the fluctuation includes at least one trough.

[0090] In an embodiment of the present invention, as an optional embodiment, in the direction from the N-type semiconductor layer 30 to the P-type semiconductor layer 70, the distribution curve of the doping concentration of the n-type impurity of the stress release layer 40 and the multi-quantum well layer 50 is an n-type impurity concentration curve; the profile change trend of the n-type impurity concentration curve is substantially the same as that of the C element concentration curve. Further, the n-type impurity includes Si element.

[0091] In an embodiment of the present invention, as an optional embodiment, the n-type impurity concentration curve includes a first n smooth curve close to the N-type semiconductor layer 30, a second n smooth curve close to the P-type semiconductor layer 70, and a third n smooth curve located between the first n smooth curve and the second n smooth curve; the n element doping concentration corresponding to the third n smooth curve is higher than the n element doping concentration corresponding to the first n smooth curve and the second n smooth curve.

[0092] In an embodiment of the present invention, as an optional embodiment, a direction from the substrate 10 to the P-type semiconductor layer 70 is defined as a first direction, and along the first direction, the third n smooth curve profile presents a distribution trend of being high at both ends and low in the middle;

[0093] Alternatively, along the first direction, the third n smooth curve profiles present a gradually decreasing distribution trend;

[0094] Alternatively, along the first direction, the third n smooth curve profiles present a gradually increasing distribution trend;

[0095] Alternatively, along the first direction, the third n smooth curve profiles present a fluctuating distribution trend; the fluctuation includes at least one trough.

[0096] In an embodiment of the present invention, as an optional embodiment, a C monotonically rising curve is provided between the first C smooth curve and the third C smooth curve, and a C monotonically falling curve is provided between the third C smooth curve and the second C smooth curve.

[0097] The C monotonically rising curve means that, in a set direction, in the corresponding epitaxial structure, the doping concentration of C increases monotonically; the C monotonically falling curve means that, in a set direction, in the corresponding epitaxial structure, the doping concentration of C decreases monotonically.

[0098] In an implementation manner of the present invention, as an optional embodiment, there are n monotonically rising curves between the first n smooth curves and the third n smooth curves, and there are n monotonically falling curves between the third n smooth curves and the second n smooth curves.

[0099] The n monotonic rising curve means that in a set direction, the doping concentration of n-type impurities in the corresponding epitaxial structure increases monotonically; the n monotonic falling curve means that in a set direction, the doping concentration of n-type impurities in the corresponding epitaxial structure decreases monotonically.

[0100] In an embodiment of the present invention, as an optional embodiment, the In oscillation curve consists of a first oscillation curve and a second oscillation curve; the amplitudes of the first oscillation curve and the second oscillation curve are different.

[0101] In an embodiment of the present invention, as an optional embodiment, the direction close to the P-type semiconductor layer 70 is a first oscillation curve, and the direction away from the P-type semiconductor layer 70 is a second oscillation curve; the amplitude of the first oscillation curve is greater than the amplitude of the second oscillation curve.

[0102] In an embodiment of the present invention, as an optional embodiment, the In oscillation curve corresponds to the second C smooth curve.

[0103] In an embodiment of the present invention, as an optional embodiment, the In oscillation curve corresponds to the multi-quantum well layer 50, wherein the concentration of In is greater than 5×10 18 atoms / cm 3 For example, >8×1018 atoms / cm 3 、>1×10 19 atoms / cm 3 、>2×10 19 atoms / cm 3 etc.

[0104] In an embodiment of the present invention, as an optional embodiment, the thickness of the multi-quantum well layer 50 is 150-280 nm. For example, in different embodiments, the thickness of the multi-quantum well layer 50 can be 150 nm, 160 nm, 170 nm, 180 nm, 190 nm, 200 nm, 210 nm, 220 nm, 230 nm, 240 nm, 250 nm, 260 nm, 270 nm, 280 nm, etc.

[0105] In an embodiment of the present invention, as an optional embodiment, the multi-quantum well layer 50 includes a first sublayer 51 and a second sublayer 52; the first sublayer 51 includes at least one group of first barrier layers and first well layers alternately stacked, and the second sublayer 52 includes at least one group of second barrier layers and second well layers alternately stacked.

[0106] In an embodiment of the present invention, as an optional embodiment, the multi-quantum well layer 50 is an InGaN / GaN multi-quantum well layer. In actual operation, the thickness of InGaN and GaN in the InGaN / GaN multi-quantum well layer can be adjusted according to actual needs.

[0107] In an embodiment of the present invention, as an optional embodiment, the first sublayer 51 is arranged between the P-type semiconductor layer 70 and the stress release layer 40, and the second sublayer 52 is arranged between the first sublayer 51 and the stress release layer 40; the average concentration of In in the first sublayer 51 is higher than the average concentration of In in the second sublayer 52.

[0108] In an embodiment of the present invention, as an optional embodiment, the first oscillation curve corresponds to the first sub-layer 51 , and the second oscillation curve corresponds to the second sub-layer 52 .

[0109] In an embodiment of the present invention, as an optional embodiment, the first C smooth curve and the third C smooth curve correspond to the stress release layer 40; the thickness of the stress release layer 40 is 150-600 nm.

[0110] For example, in different embodiments, the thickness of the stress release layer 40 can be 150nm, 180nm, 200nm, 220nm, 240nm, 250nm, 260nm, 280nm, 300nm, 320nm, 340nm, 350nm, 360nm, 380nm, 400nm, 420nm, 440nm, 450nm, 460nm, 480nm, 500nm, 520nm, 540nm, 550nm, 560nm, 580nm, 600nm, etc.

[0111] In an embodiment of the present invention, as an optional embodiment, in the third C smooth curve, the highest doping concentration of the C element is 1×10 17 ~1×10 18 atoms / cm 3 .

[0112] In an embodiment of the present invention, as an optional embodiment, in the third n smooth curve, the doping concentration of n-type impurities is 5×10 17 ~5×10 18 atoms / cm 3 .

[0113] In an embodiment of the present invention, as an optional example, the N-type semiconductor layer 30 is N-type GaN, and the P-type semiconductor layer 70 is P-type GaN.

[0114] In an embodiment of the present invention, as an optional embodiment, the N-type semiconductor layer 30 includes an undoped GaN layer and an N-type GaN layer doped with Si. The thickness of the undoped GaN layer may be 1 to 3 μm, the thickness of the N-type GaN layer doped with Si may be 1 to 3 μm, and the concentration of Si is 1×10 19 atoms / cm 3～ ~1×10 20 atoms / cm 3 , such as 3×10 19 atoms / cm 3 .

[0115] In an embodiment of the present invention, as an optional embodiment, the P-type semiconductor layer 70 is a P-type GaN layer doped with Mg. The average doping concentration of Mg is 1×10 19 ~1×10 21 atoms / cm 3 , such as 1×10 20 atoms / cm 3 Furthermore, in the first P-type semiconductor sublayer, the maximum doping concentration of C element can be 3×1017 ~9×10 17 atoms / cm 3 In the second P-type semiconductor sublayer, the minimum doping concentration of C element can be 7×10 16 ~3×10 17 atoms / cm 3 .

[0116] In an embodiment of the present invention, as an optional embodiment, the buffer layer 20 is one or more of an AlN buffer layer, a U-GaN buffer layer, or an AlGaN buffer layer, and the thickness may be 15-25 nm, such as 20 nm.

[0117] In an embodiment of the present invention, as an optional embodiment, the electron blocking layer 60 is a P-type AlGaN electron blocking layer.

[0118] In an embodiment of the present invention, as an optional embodiment, the total thickness of the P-type AlGaN electron blocking layer and the P-type GaN layer doped with Mg may be 200 nm.

[0119] An embodiment of the present invention further provides a method for preparing the light emitting diode epitaxial structure, comprising the following steps:

[0120] (1) An AlGaN buffer layer 20 with a thickness of 20 nm is grown on the surface of a sapphire substrate 10 at 550°C.

[0121] (2) Annealing treatment is performed in an NH3 atmosphere, and the temperature is raised to 1110°C to recrystallize the low-temperature AlGaN into island-shaped seed crystals.

[0122] (3) TMGa (trimethylgallium) is introduced at a pressure of 800 mbar to grow a 1 μm thick three-dimensional layer.

[0123] (4) The temperature is raised to 1150°C, the pressure is reduced to 600 mbar, and a non-doped GaN layer with a thickness of 2 μm is grown.

[0124] (5) Under the same conditions as step (4), a 2 μm thick Si-doped N-type GaN layer was grown, wherein the Si doping concentration was 3×10 19 atoms / cm 3 .

[0125] (6) Growing a stress release layer 40, comprising:

[0126] The temperature was lowered to 900°C and a carbon-doped GaN layer was grown by ion implantation at a pressure of 300 mbar as a stress release layer with a thickness of 150 to 600 nm. The carbon doping concentration was 1×10 17~1×10 18 atoms / cm 3 , and the carbon content of the stress release layer 40 is higher than that of the N-type GaN layer and the multi-quantum well layer 50; due to the indium diffusion phenomenon, a certain concentration of unintentionally doped indium exists in the stress release layer 40; because it is generated by the diffusion of indium in the multi-quantum well layer 50, its concentration is lower than the minimum value of the indium content of the multi-quantum well layer 50;

[0127] Furthermore, the growth parameters may be adjusted according to the concentration distribution trend of the C element. The concentration distribution of the C element may be as follows:

[0128] In the stress release layer 40 along the first direction, the doping concentration of the C element (i.e., the third C smooth curve) presents a distribution trend of being high at both ends and low in the middle;

[0129] Alternatively, the doping concentration of the C element (i.e., the third C smooth curve) presents a distribution trend of being low at both ends and high in the middle;

[0130] Alternatively, the doping concentration of the C element (i.e., the third C smooth curve) presents a gradually decreasing distribution trend;

[0131] Alternatively, the doping concentration of the C element (i.e., the third C smooth curve) presents a gradually increasing distribution trend;

[0132] Alternatively, the doping concentration of the C element (ie, the third C smooth curve) presents a fluctuating distribution trend; the fluctuation includes at least one trough.

[0133] (7) Growing a multi-quantum well layer 50, which may include 15 pairs of InGaN (2nm) / GaN (10nm) light-emitting layers with a total thickness of 180nm; wherein 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 (triethylgallium).

[0134] (8) The temperature is raised to 1000° C. and a P-type AlGaN electron blocking layer 60 is grown under a pressure of 200 mbar.

[0135] (9) Turn off the aluminum source, keep the conditions the same as step (8), and continue to grow the Mg-doped P-type GaN layer, i.e., the P-type semiconductor layer 70; the growth parameters can be adjusted according to the distribution trend of the C element content in the first P-type semiconductor sublayer and the second P-type semiconductor sublayer. The Mg doping concentration in the Mg-doped P-type GaN layer is 1×10 20 atoms / cm 3 .

[0136] The total thickness of the P-type AlGaN electron blocking layer 60 and the P-type semiconductor layer 70 is 200 nm.

[0137] The present invention also provides a light emitting diode, such as Figure 4 As shown, it includes any one of the above-mentioned light emitting diode epitaxial structures.

[0138] Furthermore, the light emitting diode further comprises a light emitting diode epitaxial structure current blocking layer, a current spreading layer, an N electrode, a P electrode and an insulating layer;

[0139] The current blocking layer is arranged on the P-type semiconductor layer 70 of the light-emitting diode epitaxial structure; the current spreading layer is stacked on the P-type semiconductor layer 70 in a manner of covering the current blocking layer; the P electrode is arranged on the current spreading layer and is electrically connected to the P-type semiconductor layer 70; the N electrode is arranged in the N step region and is electrically connected to the N-type semiconductor layer 30; the insulating layer covers the P electrode and the N electrode, and exposes a portion of the P electrode and the N electrode to form an opening.

[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 with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A light emitting diode epitaxial structure, characterized in that: include: A substrate, and an N-type semiconductor layer, a stress release layer, a multi-quantum well layer and a P-type semiconductor layer sequentially arranged on the substrate; In the direction from the N-type semiconductor layer to the P-type semiconductor layer, the distribution curves of the doping concentrations of the C element and the In element of the stress release layer and the multi-quantum well layer are respectively a C element concentration curve and an In element concentration curve; The In element concentration curve includes an In monotonically rising curve close to the N-type semiconductor layer and an In oscillation curve close to the P-type semiconductor layer connected to the top of the In monotonically rising curve; In the C element concentration curve, the C element doping concentration at a position corresponding to the In oscillation curve is lower than the C element doping concentration at a position corresponding to the In monotonically rising curve; In the direction from the N-type semiconductor layer to the P-type semiconductor layer, the P-type semiconductor layer at least includes a first P-type semiconductor sublayer and a second P-type semiconductor sublayer in sequence, and the C element content in the first P-type semiconductor sublayer is higher than the C element content in the second P-type semiconductor sublayer.

2. The light emitting diode epitaxial structure according to claim 1, characterized in that: The ratio of the highest content of the C element in the first P-type semiconductor sublayer to the lowest content of the C element in the second P-type semiconductor sublayer is ≥3; Preferably, the ratio of the highest content of the C element in the first P-type semiconductor sublayer to the lowest content of the C element in the second P-type semiconductor sublayer is 3.5-5.

3. The light emitting diode epitaxial structure according to claim 1, characterized in that: The C element content in the first P-type semiconductor sublayer and the C element content in the second P-type semiconductor sublayer are both higher than the C element content in the multi-quantum well layer.

4. The light emitting diode epitaxial structure according to claim 1, characterized in that: The first P-type semiconductor sublayer and the second P-type semiconductor sublayer are both doped with In element.

5. The light emitting diode epitaxial structure according to claim 1, characterized in that: The C element concentration curve is approximately in the shape of a figure "X", including a first C smooth curve close to the N-type semiconductor layer, a second C smooth curve close to the P-type semiconductor layer, and a third C smooth curve located between the first C smooth curve and the second C smooth curve; the C element doping concentration corresponding to the third C smooth curve is higher than the C element doping concentration corresponding to the first C smooth curve and the second C smooth curve.

6. The light emitting diode epitaxial structure according to claim 5, characterized in that: Having at least one of the following characteristics: (1) The In oscillation curve corresponds to the second C smooth curve; the In monotonically rising curve corresponds to a portion of the third C smooth curve; (2) the C element doping concentration corresponding to the first C smooth curve is higher than the C element doping concentration corresponding to the second C smooth curve; (3) a distribution curve of the doping concentration of the C element in the P-type semiconductor layer has at least one peak and one valley; (4) The distribution curve of the doping concentration of the In element in the P-type semiconductor layer has at least two peaks.

7. The light emitting diode epitaxial structure according to claim 5, characterized in that: A direction from the substrate to the P-type semiconductor layer is defined as a first direction, and along the first direction, the third C smooth curve presents a distribution trend of being high at both ends and low in the middle; Alternatively, along the first direction, the third C smooth curve presents a distribution trend of low ends and high middle; Alternatively, along the first direction, the third C smooth curve presents a gradually decreasing distribution trend; Alternatively, along the first direction, the third C smooth curve presents a gradually increasing distribution trend; Alternatively, along the first direction, the third C smooth curve presents a fluctuating distribution trend; the fluctuation includes at least one trough.

8. The light emitting diode epitaxial structure according to claim 1, characterized in that: In the direction from the N-type semiconductor layer to the P-type semiconductor layer, the distribution curve of the doping concentration of the n-type impurities of the stress release layer and the multi-quantum well layer is an n-type impurity concentration curve; the profile change trend of the n-type impurity concentration curve is substantially the same as that of the C element concentration curve; Preferably, the n-type impurity includes Si element; Preferably, the n-type impurity concentration curve includes a first n smooth curve close to the N-type semiconductor layer, a second n smooth curve close to the P-type semiconductor layer, and a third n smooth curve located between the first n smooth curve and the second n smooth curve; the n-type impurity doping concentration corresponding to the third n smooth curve is higher than the n-type impurity doping concentration corresponding to the first n smooth curve and the second n smooth curve; Preferably, there are n monotonically rising curves between the first n smooth curves and the third n smooth curves, and there are n monotonically falling curves between the third n smooth curves and the second n smooth curves.

9. The light emitting diode epitaxial structure according to claim 8, characterized in that: A direction from the substrate to the P-type semiconductor layer is defined as a first direction, and along the first direction, the third n smooth curve profile presents a distribution trend of being high at both ends and low in the middle; Alternatively, along the first direction, the third n smooth curve profiles present a gradually decreasing distribution trend; Alternatively, along the first direction, the third n smooth curve profiles present a gradually increasing distribution trend; Alternatively, along the first direction, the third n smooth curve profiles present a fluctuating distribution trend; the fluctuation includes at least one trough.

10. The light emitting diode epitaxial structure according to claim 5, characterized in that: Having at least one of the following characteristics: (1) There is a C monotonically rising curve between the first C smooth curve and the third C smooth curve, and there is a C monotonically falling curve between the third C smooth curve and the second C smooth curve; (2) The In oscillation curve corresponds to the second C smooth curve; the C element doping concentration corresponding to the second C smooth curve is between the C element doping concentrations corresponding to the first C smooth curve and the third C smooth curve.

11. The light emitting diode epitaxial structure according to claim 1, characterized in that: Having at least one of the following characteristics: (1) The In oscillation curve consists of a first oscillation curve and a second oscillation curve; the amplitudes of the first oscillation curve and the second oscillation curve are different; (2) The In oscillation curve corresponds to the multi-quantum well layer, where the concentration of In is greater than 5×10 18 atoms / cm 3 .

12. The light emitting diode epitaxial structure according to claim 11, characterized in that: Having at least one of the following characteristics: (1) The thickness of the multi-quantum well layer is 150 to 280 nm; (2) the multi-quantum well layer comprises a first sublayer and a second sublayer; the first sublayer comprises at least one set of first barrier layers and first well layers alternately stacked, and the second sublayer comprises at least one set of second barrier layers and second well layers alternately stacked; (3) The first sublayer is disposed between the P-type semiconductor layer and the stress release layer, and the second sublayer is disposed between the first sublayer and the stress release layer; an average concentration of In in the first sublayer is higher than an average concentration of In in the second sublayer; (4) The first oscillation curve corresponds to the first sub-layer, and the second oscillation curve corresponds to the second sub-layer.

13. The light emitting diode epitaxial structure according to claim 5, characterized in that: The first C smooth curve and the third C smooth curve correspond to the stress release layer; the thickness of the stress release layer is 150 to 600 nm; and / or, In the third C smooth curve, the highest doping concentration of C element is 1×10 17 ~1×10 18 atoms / cm 3 .

14. The light emitting diode epitaxial structure according to claim 8, characterized in that: In the third n smooth curve, the doping concentration of n-type impurities is 5×10 17 ~5×10 18 atoms / cm 3 .

15. A light emitting diode, characterized in that The light emitting diode epitaxial structure comprises the light emitting diode epitaxial structure according to any one of claims 1 to 14, and an N-electrode and a P-electrode electrically connected to the N-type semiconductor layer and the P-type semiconductor layer respectively.

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