Light emitting element

Abstract

This invention discloses a light-emitting element comprising an n-type nitride semiconductor structure; a stress-relieving structure is located on the n-type nitride semiconductor structure, comprising a plurality of narrow bandgap layers and a plurality of wide bandgap layers stacked alternately, wherein one of the plurality of wide bandgap layers comprises a plurality of wide bandgap sublayers and at least one of the plurality of wide bandgap sublayers comprises Al. s6 Ga (1‑s6) N; An active structure is located on the stress-relieving structure, comprising multiple quantum well layers and multiple barrier layers stacked alternately, wherein one of the multiple barrier layers comprises multiple barrier sublayers and at least one of the multiple barrier sublayers contains Al. s8 Ga (1‑s8) N, the absolute aluminum composition of the wide bandgap sublayer is greater than or equal to the absolute aluminum composition of the barrier sublayer, and the average aluminum composition of the wide bandgap sublayer is greater than the average aluminum composition of the barrier sublayer; an electron blocking structure is located on the active structure; and a p-type nitride semiconductor structure is located on the electron blocking structure.

Description

Technical Field

[0001] The present invention relates to a light-emitting element, and more particularly to a light-emitting element comprising a quantum well layer and a barrier layer made of nitride semiconductor material as active structures. Background Technology

[0002] Light-emitting diodes (LEDs) are solid-state semiconductor light-emitting devices. Their advantages include low power consumption, low heat generation, long lifespan, shock resistance, small size, fast response speed, and excellent photoelectric properties, such as a stable emission wavelength. Therefore, LEDs are widely used in household appliances, equipment indicator lights, and optoelectronic products. Summary of the Invention

[0003] A light-emitting element includes an n-type nitride semiconductor structure; a stress-relieving structure is located on the n-type nitride semiconductor structure, comprising a plurality of narrow bandgap layers and a plurality of wide bandgap layers stacked alternately, wherein one of the plurality of wide bandgap layers comprises a plurality of wide bandgap sublayers and at least one of the plurality of wide bandgap sublayers comprises Al. s6 Ga (1-s6) N; An active structure is located on the stress-relieving structure, comprising multiple quantum well layers and multiple barrier layers stacked alternately, wherein one of the multiple barrier layers comprises multiple barrier sublayers and at least one of the multiple barrier sublayers contains Al. s8 Ga (1-s8) N, the absolute aluminum composition of the wide bandgap sublayer is greater than or equal to the absolute aluminum composition of the barrier sublayer, and the average aluminum composition of the wide bandgap sublayer is greater than the average aluminum composition of the barrier sublayer; an electron blocking structure is located on the active structure; and a p-type nitride semiconductor structure is located on the electron blocking structure. Attached Figure Description

[0004] Figure 1 This is a cross-sectional view of the light-emitting element 1 according to an embodiment of the present invention;

[0005] Figure 2 This is a partial transmission electron microscope (TEM) image of the light-emitting element 1 according to an embodiment of the present invention.

[0006] Figure 3 This is a schematic diagram of the periodic structure 10;

[0007] Figure 4 This is a schematic diagram of the stress relief structure 12;

[0008] Figure 5 This is a schematic diagram of the active structure 14;

[0009] Figure 6This is a secondary ion mass spectrometer (SIMS) analysis diagram of the light-emitting element 1 according to an embodiment of the present invention.

[0010] Figure 7 The energy dispersive X-ray spectrum (EDX) of the light-emitting element 1 according to an embodiment of the present invention;

[0011] Figure 8 This is a schematic diagram of a light-emitting device 2 according to an embodiment of the present invention;

[0012] Figure 9 This is a schematic diagram of a light-emitting device 3 according to an embodiment of the present invention.

[0013] Symbol Explanation

[0014] 1: Light-emitting element

[0015] 4: Substrate

[0016] 40: Countertop

[0017] 41: convex part

[0018] 40S: Upper surface

[0019] 5: Buffer structure

[0020] 7: Grassroots

[0021] 8: n-type nitride semiconductor structure

[0022] 10: Periodic Structure

[0023] 10A: First semiconductor layer

[0024] 10B: Second semiconductor layer

[0025] 12: Stress relief structure

[0026] 12A: Narrow bandgap layer

[0027] 12A1: First narrow bandgap layer

[0028] 12A2: Second narrow bandgap layer

[0029] 12B: Wide bandgap layer

[0030] 12B1: First wide bandgap layer

[0031] 12B2: The second wide bandgap layer

[0032] 121b, 121b1, 121b2: First wide bandgap sublayer

[0033] 122b, 122b1, 122b2: Second wide bandgap sublayer

[0034] 123b, 123b1, 123b2: Third wide bandgap sublayer

[0035] 14: Active structure

[0036] 14B: Barrier Layer

[0037] 14B1: First barrier layer

[0038] 14B2: Second barrier layer

[0039] 141b, 141b1, 141b2: First barrier sublayer

[0040] 142b, 142b1, 142b2: Second barrier sublayer

[0041] 143b, 143b1, 143b2: Third barrier sublayer

[0042] 144: Cap layer

[0043] 14W: Quantum well layer

[0044] 14W1: First quantum well layer

[0045] 14W2: Second quantum well layer

[0046] 14LB: Final Barrier Layer

[0047] 16: Electron blocking structure

[0048] 17: p-type nitride semiconductor structure

[0049] 18: Contact layer

[0050] 21: n-side electrode

[0051] 23: Transparent conductive layer

[0052] 25: p-side electrode

[0053] 27: Insulation layer

[0054] 2: Light-emitting device

[0055] 3: Light-emitting device

[0056] 51: Packaging substrate

[0057] 511: First gasket

[0058] 512: Second gasket

[0059] 53: Insulation section

[0060] 54: Reflective Structure

[0061] 602: Lampshade

[0062] 604: Reflector

[0063] 606: Bearing section

[0064] 608: Light-emitting unit

[0065] 611: Light-emitting module

[0066] 612: Lamp holder

[0067] 614: Heatsink

[0068] 616: Connecting part

[0069] 618: Electrical connection element Detailed Implementation

[0070] To make the description of the present invention more detailed and complete, please refer to the following description of the embodiments and related illustrations. However, the embodiments shown below are for illustrating the light-emitting element of the present invention and are not intended to limit the present invention to the following embodiments. Furthermore, the dimensions, materials, shapes, relative arrangements, etc., of the constituent parts described in the embodiments in this specification are not limited thereto, and the scope of the present invention is not limited thereto, but merely described. Also, the size or positional relationship of the components shown in the illustrations may be exaggerated for clarity. In addition, other layers / structures or steps may be incorporated into the following embodiments. For example, the description of "forming a second layer / structure on a first layer / structure" may include embodiments where the first layer / structure directly contacts the second layer / structure, or embodiments where the first layer / structure indirectly contacts the second layer / structure, that is, other layers / structures exist between the first layer / structure and the second layer / structure. Furthermore, the spatial relative relationship between the first layer / structure and the second layer / structure may change depending on the operation or use of the device. The first layer / structure itself is not limited to a single layer or a single structure; the first layer may contain multiple sub-layers, and the first structure may contain multiple layers. Furthermore, in the following description, to appropriately omit detailed descriptions, components of the same or similar nature will be shown with the same name and symbol.

[0071] Before describing the embodiments of the present invention, the following should be explained first. Firstly, in this specification, A1... x In y Ga (1-x-y) N represents a 1:1 chemical composition ratio of Group III elements (Al, Ga, and In) to N. Al, In, and Ga can be any compound with varying compositional ratios. x Ga (1-x)N indicates a 1:1 chemical composition ratio of Group III elements (the sum of Al and Ga) to N. Al and Ga in Group III can be any compounds with varying compositional ratios. Furthermore, if only labeled AlN and GaN, it indicates that Ga and Al are not included in the compositional ratio, respectively. It should be noted that Al... x In y Ga (1-x-y) The absolute composition of Al, In, or Ga in N can be determined using known quantitative analyses, such as energy-dispersive X-ray spectroscopy (EDX) or X-ray diffractometer (XRD). x In y Ga (1-x-y) Taking N as an example, in this specification, the sum of Al, Ga, and In is 1. When the absolute composition of Al is x, the absolute composition of In is y, the absolute composition of Ga is (1-xy).

[0072] Furthermore, in this specification, layers that function electrically in a p-type manner are referred to as p-type layers, and layers that function electrically in an n-type manner are referred to as n-type layers. On the other hand, layers that do not function electrically in a p-type or n-type manner without the intentional addition of specific impurities such as magnesium (Mg) or silicon (Si) are referred to as "i-type" or "undoped". Undoped layers may inevitably contain impurities during the manufacturing process; specifically, when the doping concentration is less than 1 × 10⁻⁶, impurities may be introduced. 17 / cm 3 At this time, it is referred to as "undoped" in this specification. In addition, the concentration values ​​of impurities such as magnesium (Mg) and silicon (Si) are obtained by secondary ion mass spectrometry (SIMS) analysis.

[0073] Figure 1 This is a cross-sectional view of a light-emitting element 1 according to an embodiment of the present invention. The light-emitting element 1 includes a substrate 4, and a buffer structure 5, a base layer 7, an n-type nitride semiconductor structure 8, a periodic structure 10, a stress-relieving structure 12, an active structure 14, an electron blocking structure 16, a p-type nitride semiconductor structure 17, and a contact layer 18 are sequentially stacked on the upper surface 40S of the substrate 4.

[0074] The light-emitting element 1 includes a mesa 40, a portion of an n-type nitride semiconductor structure 8 is exposed outside the mesa 40, and an n-side electrode 21 is formed on the exposed portion. A p-side electrode 25 is formed on the p-type nitride semiconductor structure 17 and the contact layer 18. A transparent conductive layer 23 is formed between the p-side electrode 25 and the contact layer 18.

[0075] The substrate 4 has a sufficient thickness to support the layers and structures located thereon, for example, not less than 30 μm, and more preferably not more than 300 μm. The substrate 4 includes sapphire (Al2O3) wafers, gallium nitride (GaN) wafers, silicon carbide (SiC) wafers, or aluminum nitride (AlN) wafers for epitaxial growth of gallium nitride (GaN), indium gallium nitride (InGaN), or aluminum gallium nitride (AlGaN). The upper surface 40S of the substrate 4 in contact with the buffer structure 5 can be a roughened surface. The roughened surface can be a surface with an irregular shape or a surface with a regular shape. Figure 1 As shown, relative to the upper surface 40S of the substrate 4, the substrate 4 includes one or more protrusions 41 protruding from the upper surface 40S, or one or more recesses (not shown) recessed into the upper surface 40S. In a cross-sectional view, the protrusions 41 or recesses (not shown) can be hemispherical or pyramidal. In one embodiment, the protrusions 41 contain a material different from the substrate 4, such as a semiconductor material, an insulating material, or a conductive material. Semiconductor materials include compound semiconductor materials, such as III-V semiconductor materials, II-VI semiconductor materials, or silicon carbide (SiC). Insulating materials include oxides, nitrides, or oxides of nitride. Oxides include silicon oxide, zinc oxide, aluminum oxide, or titanium oxide. Nitrates include silicon nitride, aluminum nitride, or titanium nitride. Oxides of nitride include aluminum oxynitride. Conductive materials include indium tin oxide. The material of the protrusions 41 can be selected to have a refractive index between that of the substrate 4 and the semiconductor layers and structures thereon, in order to improve the light extraction efficiency of the light-emitting element 1. In other embodiments, the upper surface 40S of the substrate 4 in contact with the buffer structure 5 is a flat surface.

[0076] In one embodiment of the present invention, a buffer structure 5, a base layer 7, an n-type nitride semiconductor structure 8, a periodic structure 10, a stress-relieving structure 12, an active structure 14, an electron-blocking structure 16, a p-type nitride semiconductor structure 17, and / or a contact layer 18 are formed on a substrate 4 by metal-organic chemical vapor deposition (MOCVD), molecular beam epitaxy (MBE), hydride vapor deposition (HVPE), physical vapor deposition (PVD), or ion plating. The physical vapor deposition method includes sputtering or evaporation.

[0077] The buffer structure 5 is designed to reduce defects and improve the quality of the epitaxial layer grown thereon. The buffer structure 5 may comprise a single layer or multiple layers (not shown). When the buffer structure 5 comprises multiple layers (not shown), the multiple layers may comprise the same material or different materials. In one embodiment, the buffer structure 5 comprises a first layer and a second layer, wherein the first layer is grown by sputtering and the second layer is grown by metal-organic chemical vapor deposition (MOCVD). In one embodiment, the buffer structure 5 further comprises a third layer. The third layer is grown by MOCVD, and the growth temperature of the second layer is higher or lower than the growth temperature of the third layer. In one embodiment, the first, second, and third layers comprise the same material, such as aluminum nitride (AlN), or comprise different materials, such as any combination of aluminum nitride (AlN), gallium nitride (GaN), and aluminum gallium nitride (AlGaN). In other embodiments, the buffer structure 5 includes PVD-aluminum nitride (PVD-AlN), wherein the target material used to form PVD-aluminum nitride is composed of aluminum nitride, or an aluminum target material is used and aluminum nitride (AlN) is reactively formed in the presence of a nitrogen source.

[0078] In one embodiment, the buffer structure 5 may be undoped, i.e., not intentionally doped. In another embodiment, the buffer structure 5 may contain a dopant, such as carbon (C), hydrogen (H), oxygen (O), or any combination thereof, and the concentration of this dopant in the buffer structure 5 is not less than 1 × 10⁻⁶. 17 / cm 3 .

[0079] Buffer structure 5 contains Al x1 Ga (1-x1) N (0≤x1≤1), and preferably an AlN layer or a GaN layer. The thickness of the buffer structure 5 is not particularly limited, and preferably greater than or equal to 3nm and less than or equal to 150nm, and more preferably greater than or equal to 5nm and less than or equal to 80nm.

[0080] Basic level 7 includes AI s1 In t1 Ga (1-s1-t1) N(0≤s1≤1, 0≤t1≤1), preferably containing Al s1 Ga (1-s1)N (0≤s1≤1), and more preferably GaN layer. The base layer 7 can prevent crystal defects present in the buffer structure 5 from propagating from the base layer 7 to the active structure 14. The base layer 7 may include n-type impurities or not. When the base layer 7 does not include n-type impurities, the excellent crystallinity of the base layer 7 can be maintained. Therefore, it is preferred that the base layer 7 does not include n-type impurities, and the defects in the base layer 7 are reduced by increasing the thickness of the base layer 7. However, if the thickness of the base layer 7 is increased to a certain extent, the effect of the increase in the thickness of the base layer 7 on its defect reduction becomes saturated. Thus, the thickness of the base layer 7 is preferably greater than or equal to 2 μm and less than or equal to 8 μm, more preferably less than or equal to 6 μm, and more preferably less than or equal to 4 μm. In one embodiment, when the substrate 4 includes a plurality of protrusions 41 protruding from the upper surface 40S of the substrate 4, the thickness of the base layer 7 is preferably 0.5 μm thicker than the height of the protrusions 41 to completely cover the plurality of protrusions 41 and form a flat surface.

[0081] n-type nitride semiconductor structure 8 Al containing n-type impurities s2 In t2 Ga (1-s2-t2) N (0≤s2≤1, 0≤t2≤1), preferably Al containing n-type impurities s2 Ga (1-s2) N (0≤s2≤1, preferably 0≤s2≤0.1, more preferably 0.001≤s2≤0.01). The n-type nitride semiconductor structure 8 can be a single layer or formed into multiple layers through multiple growth steps. The multiple layers can have the same or different compositions, and the multiple layers can have the same or different thicknesses. In one embodiment, the n-type nitride semiconductor structure 8 includes an n-type contact layer (not shown), a portion of which is exposed outside the mesa 40, an n-side electrode 21 that can contact the n-type contact layer, and a modulation layer (not shown) located between the n-type contact layer and the substrate 7. The doping concentration of the n-type impurities in the n-type contact layer is the highest among the multiple layers of the n-type nitride semiconductor structure 8, and is also higher than the n-type doping concentration of the substrate 7. The n-type contact layer may include a first n-type contact sublayer and a second n-type contact sublayer stacked alternately 7 to 40 times. The thickness of the n-type contact layer is preferably 0.4 μm to 4 μm, more preferably 0.8 μm to 3 μm, and even more preferably 1 μm to 2 μm. The thicknesses of the first n-type contact layer and the second n-type contact layer are respectively 10 nm to 100 nm, more preferably 20 nm to 80 nm, and even more preferably 30 nm to 70 nm. The first n-type contact layer contains Al. x Ga (1-x) N, where 0 ≤ x < 1; preferably, 0 ≤ x < 0.1; preferably, 0 ≤ x < 0.05; preferably, 0 ≤ x < 0.005; more preferably, x is substantially 0. The second n-type contact sublayer contains Al. y Ga1-y N, where 0 < y < 1; preferably, 0 < y ≤ 0.1; preferably, 0 < y ≤ 0.05; preferably, 0 < y ≤ 0.01; more preferably, 0 < y ≤ 0.005. In one embodiment, y > x. For example, the material of the first n-type contact layer is gallium nitride (GaN), and the second n-type contact layer is aluminum gallium nitride (AlGaN). The first n-type contact layer has a higher n-type doping concentration, and the second n-type contact layer has a lower n-type doping concentration, thereby improving the lateral current dispersion and further enhancing the electrostatic discharge (ESD) breakdown resistance and luminous efficiency of the light-emitting element 1. The n-type doping concentration of the modulation layer is between the n-type contact layer and the substrate 7, and / or the lattice constant of the material of the modulation layer is between the n-type contact layer and the substrate 7, and / or the growth temperature of the modulation layer is between the n-type contact layer and the substrate 7, so as to modulate the differences in doping concentration, material, and growth condition parameters between the n-type contact layer and the substrate 7, reducing the epitaxial defects of the layers above the modulation layer and improving the quality of the epitaxial layer. In one embodiment, the modulation layer comprises an AlInGaN series material, such as comprising Al z1 In z2 Ga (1-z1-z2) N, where 0 ≤ z2 < z1 ≤ 1. In another embodiment, the modulation layer comprises Al z Ga 1-z N, where 0 ≤ z ≤ 1. In another embodiment, when the n-type contact layer comprises Al y Ga 1-y N, the modulation layer comprises Al z Ga 1-z N. Preferably, y ≤ z ≤ 0.1, more preferably y ≤ z ≤ 0.05, where the thickness of the modulation layer is less than the thickness of the first n-type contact layer and / or the second n-type contact layer, for example, less than 10 nm.

[0082] The n-type impurities in the aforementioned n-type nitride semiconductor structure 8 include silicon (Si), carbon (C), or germanium (Ge), preferably silicon (Si). The n-type doping concentration in the n-type nitride semiconductor structure 8 is preferably less than or equal to 5×10 19 cm -3 , more preferably less than or equal to 2×10 19 cm -3 , and greater than or equal to 1×10 18 cm -3 , more preferably greater than or equal to 4×10 18 cm -3Since the impedance of the n-type nitride semiconductor structure 8 decreases more as its thickness increases, the thickness of the n-type nitride semiconductor structure 8 is preferably increased. However, as the thickness of the n-type nitride semiconductor structure 8 increases, the production cost also increases. Therefore, from the perspective of production and manufacturing, the thickness of the n-type nitride semiconductor structure 8 is preferably 1 μm to 6 μm, more preferably 1.5 μm to 4.5 μm, and even more preferably 2 μm to 3.5 μm.

[0083] As Figure 1 shown, the periodic structure 10 is disposed between the n-type nitride semiconductor structure 8 and the active structure 14. Figure 3 is a schematic structural view of the periodic structure 10.

[0084] As Figure 3 shown, the periodic structure 10 may be formed by alternately stacking a plurality of first semiconductor layers 10A and a plurality of second semiconductor layers 10B for several periods. The thickness of one period is the sum of the thickness of one first semiconductor layer 10A and the thickness of one second semiconductor layer 10B. In one embodiment, the thickness of one period in the periodic structure 10 is greater than the thickness of one period of the active structure 14 and the thickness of one period of the stress relief structure 12 described below. The thickness of the first semiconductor layer 10A is less than the thickness of the second semiconductor layer 10B. Specifically, the first semiconductor layer 10A has a thickness between 0.5 nm and 8 nm, preferably between 1 nm and 3 nm, and the second semiconductor layer 10B has a thickness between 10 nm and 60 nm, preferably between 20 nm and 50 nm. The first semiconductor layer 10A contains In t3 Ga (1-t3) N (0 < t3 < 1), preferably 0.005 < t3 < 0.1, and more preferably 0.01 < t3 < 0.05. The second semiconductor layer 10B is preferably, for example, In t4 Ga (1-t4) N (0 ≤ t4 < 1, t4 < t3), and more preferably a GaN layer without indium (In). The number of periods of the alternating stacking of the first semiconductor layer 10A and the second semiconductor layer 10B may be, for example, 2 to 20, preferably 3 to 15, and more preferably 4 to 10.

[0085] The first semiconductor layer 10A and / or the second semiconductor layer 10B contains n-type impurity doping or is undoped. In one embodiment, if both the first semiconductor layer 10A and the second semiconductor layer 10B are undoped or the concentration of doped n-type impurities is too low, the driving voltage of the light-emitting element will increase. Preferably, at least one of the first semiconductor layer 10A and the second semiconductor layer 10B contains n-type impurities. In one embodiment, when the n-type doping concentration of the periodic structure 10 is too high, the film quality of the periodic structure 10 deteriorates, which in turn affects the film quality of the active structure 14 formed on the periodic structure 10, and the light-emitting efficiency of the active structure 14 may also deteriorate. In one embodiment, the n-type doping concentration in the periodic structure 10 is less than the n-type doping concentration in the n-type nitride semiconductor structure 8. In one embodiment, the n-type doping concentration in the periodic structure 10 is preferably 1 / 10 of the n-type doping concentration in the n-type nitride semiconductor structure 8, and more preferably 1 / 2 of the n-type doping concentration of the n-type nitride semiconductor structure 8. In one embodiment, the n-type doping concentration of the periodic structure 10 is preferably less than 5×10 18 cm -3 , but greater than or equal to 1×10 17 cm -3 . In one embodiment, the first semiconductor layer 10A containing indium (In) does not contain n-type impurities, and the second semiconductor layer 10B not containing indium (In) contains n-type impurities. The first semiconductor layer 10A of the periodic structure 10 is preferably undoped with n-type impurities and is In t3 Ga (1-t3) N(0<t3<1), and the second semiconductor layer 10B is preferably GaN doped with n-type impurities. When the periodic structure 10 contains indium (In), the indium (In) composition in the periodic structure 10 is preferably higher than that in the n-type nitride semiconductor structure 8, but lower than the indium (In) composition in the stress release structure 12 and the active structure 14 described below, so that the epitaxial lattice smoothly transitions from the n-type nitride semiconductor structure 8 to the active structure 14.

[0086] Although Figure 3 the second semiconductor layer 10B is illustrated as the bottom layer and the first semiconductor layer 10A is the top layer, the bottom layer of the periodic structure 10 can also be the first semiconductor layer 10A and the top layer is the second semiconductor layer 10B.

[0087] As Figure 1 shown, the stress release structure 12 is disposed between the active structure 14 and the n-type nitride semiconductor structure 8. Figure 4 is a schematic structural view of the stress release structure 12. Figure 5 is a schematic structural view of the active structure 14.

[0088] The lattice mismatch between the InGaN quantum well layer and the GaN barrier layer of the active structure 14 affects the epitaxial quality of the active structure 14. Therefore, a stress relief structure 12 is grown before the active structure 14 to reduce lattice defects. Since the mobility of electrons is much faster than that of holes, electrons are uniformly distributed in the active structure 14, while the distribution of holes gradually decreases from near the p-type nitride semiconductor structure 17 to away from the p-type nitride semiconductor structure 17, resulting in some electrons being unable to radiatively recombine with holes and thus reducing the light emission efficiency of the LED. The present invention increases the radiative recombination efficiency of holes and electrons in the active structure 14 by adjusting the energy gaps of the stress relief structure 12, the active structure 14, and the electron blocking structure 16.

[0089] As Figure 4 shown, the stress relief structure 12 is formed by alternately stacking a plurality of narrow energy gap layers 12A and a plurality of wide energy gap layers 12B for several cycles. The thickness of one cycle is the sum of the thickness of one narrow energy gap layer 12A and the thickness of one wide energy gap layer 12B, which is less than the thickness of one cycle of the active structure 14 described below and less than the thickness of one cycle of the periodic structure 10 described above. The thickness of the narrow energy gap layer 12A is less than the thickness of the wide energy gap layer 12B. Specifically, the narrow energy gap layer 12A has a thickness between 1 nm and 3 nm, and the wide energy gap layer 12B has a thickness between 4 nm and 12 nm, preferably between 6 nm and 10 nm. The energy gap of the wide energy gap layer 12B is greater than the energy gap of the narrow energy gap layer 12A. Specifically, the narrow energy gap layer 12A contains Al s5 In t5 Ga (1-s5-t5) N (0 ≤ s5 < 1, 0 < t5 < 1), preferably In t5 Ga (1-t5) N (0 < t5 < 1), and more preferably t5 ≤ 0.1. The wide energy gap layer 12B contains Al s6 In t6 Ga (1-s6-t6) N (0 ≤ s6 < 1, 0 ≤ t6 < 1, t6 < t5, s5 < s6), such as an Al s6 Ga (1-s6) N layer and / or a GaN layer, where preferably 0 < s6 ≤ 0.08, and more preferably 0 < s6 ≤ 0.05. The number of cycles of alternately stacking the narrow energy gap layer 12A and the wide energy gap layer 12B can be, for example, 2 to 10, preferably 3 to 8, and more preferably 4 to 6.

[0090] The multiple narrow bandgap layers 12A include a first narrow bandgap layer 12A1 and a second narrow bandgap layer 12A2. The multiple wide bandgap layers 12B include a first wide bandgap layer 12B1 and a second wide bandgap layer 12B2. In a growth direction of the stress relief structure 12, the period formed by the first wide bandgap layer 12B1 and the first narrow bandgap layer 12A1, and the period formed by the second wide bandgap layer 12B2 and the second narrow bandgap layer 12A2 are each illustrated as 1 in this example, but are not limited to the number illustrated in the figure. For example, the period formed by the first wide bandgap layer 12B1 and the first narrow bandgap layer 12A1 can be configured to be more than 2, and multiple first wide bandgap layers 12B1 and multiple first narrow bandgap layers 12A1 can be alternately stacked to form a first group of the stress relief structure 12. The period formed by the second wide bandgap layer 12B2 and the second narrow bandgap layer 12A2 can be configured to be more than 2, and multiple second wide bandgap layers 12B2 and multiple second narrow bandgap layers 12A2 can be alternately stacked to form a second group of the stress relief structure 12. Preferably, the period number and / or the total thickness of the narrow bandgap layer 12A and the wide bandgap layer 12B are not greater than the period number and / or the total thickness of the active structure 14 described below to avoid absorbing the light emitted by the active structure 14 and reducing the light extraction efficiency of the light emitting element 1. As Figure 2 shown, in one embodiment, the stress relief structure 12 has a total thickness between 30 nm and 100 nm, less than the total thickness of the active structure 14 and less than the total thickness of the periodic structure 10.

[0091] At least one of the multiple wide bandgap layers 12B includes multiple wide bandgap sub-layers. In this embodiment, each of the multiple wide bandgap layers 12B includes a first wide bandgap sub-layer 121b, a second wide bandgap sub-layer 122b, and a third wide bandgap sub-layer 123b, where the second wide bandgap sub-layer 122b is located between the first wide bandgap sub-layer 121b and the third wide bandgap sub-layer 123b. The bandgap of the second wide bandgap sub-layer 122b is greater than the bandgaps of the first wide bandgap sub-layer 121b and the third wide bandgap sub-layer 123b. The first wide bandgap sub-layer 121b and the third wide bandgap sub-layer 123b preferably include GaN. The second wide bandgap sub-layer 122b includes Al s6 Ga (1-s6) N(0 < s6 < 1), preferably 0 < s6 ≤ 0.08, more preferably 0 < s6 ≤ 0.05.

[0092] In another embodiment, the plurality of wide bandgap layers 12B further include a capping layer (not shown) having GaN contacting the narrow bandgap layer 12A, and an intermediate sublayer (not shown) located between the capping layer and the first wide bandgap sublayer 121b. The intermediate sublayer includes a lattice constant less than that of the other sublayers of the wide bandgap layer 12B, and can be formed of a ternary compound semiconductor or a binary compound semiconductor having Al and N, such as AlGaN or AlN. Preferably, the intermediate sublayer is formed after each narrow bandgap layer 12A, and the thickness of the intermediate sublayer is adjusted to compensate for the compressive stress of the narrow bandgap layer 12A. The intermediate sublayer includes a thickness less than that of the other sublayers of the wide bandgap layer 12B, for example...

[0093] The first wide bandgap sublayer 121b and the third wide bandgap sublayer 123b each have a thickness less than that of the second wide bandgap sublayer 122b. The first wide bandgap sublayer 121b, the second wide bandgap sublayer 122b, and the third wide bandgap sublayer 123b each have a thickness greater than 1 nm but less than 5 nm. The thickness of the second wide bandgap sublayer 122b and the thickness of the wide bandgap sublayer 12B have a first thickness ratio between 45% and 55%. Preferably, it contains Al. s6 Ga (1-s6) The second wide bandgap sublayer 122b of N is closer to the n-type nitride semiconductor structure 8 than the third wide bandgap sublayer 123b containing GaN to block electrons earlier. The sum of the thickness of the first wide bandgap sublayer 121b and the thickness of the second wide bandgap sublayer 122b is greater than or less than the thickness of the third wide bandgap sublayer 123b. In one embodiment, the first wide bandgap sublayer 121b and the third wide bandgap sublayer 123b have substantially the same or different thicknesses.

[0094] Multiple wide bandgap layers 12B may be included, wherein the second wide bandgap layer 12B2, which is closer to the active structure 14, has a greater thickness than the first wide bandgap layer 12B1, which is farther from the active structure 14, but the thickness difference between the first wide bandgap layer 12B1 and the second wide bandgap layer 12B2 is no greater than 3 nm, preferably no greater than 2 nm. Multiple narrow bandgap layers 12A, such as the first narrow bandgap layer 12A1, which is farther from the active structure 14, and the second narrow bandgap layer 12A2, which is closer to the active structure 14, may have approximately the same thickness.

[0095] In this embodiment, the first wide bandgap sub-layer 121b is closer to the n-type nitride semiconductor structure 8 than the second wide bandgap sub-layer 122b, and the second wide bandgap sub-layer 122b is closer to the n-type nitride semiconductor structure 8 than the third wide bandgap sub-layer 123b. The first wide bandgap sub-layer 121b and the third wide bandgap sub-layer 123b respectively contact two opposite sides of the narrow bandgap layer 12A. Doping the wide bandgap layer 12B with n-type impurities can improve the electron injection efficiency. At least one of the first wide bandgap sub-layer 121b and the third wide bandgap sub-layer 123b contains n-type impurities, and the n-type impurities are preferably silicon (Si). In one embodiment, it is preferred to dope n-type impurities before the narrow bandgap layer 12A, for example, doping n-type impurities in the third wide bandgap sub-layer 123b formed before and in direct contact with the narrow bandgap layer 12A. The n-type doping concentration of the first wide bandgap sub-layer 121b and / or the third wide bandgap sub-layer 123b is preferably less than 1×10 18 cm -3 , but greater than or equal to 1×10 17 cm -3 . When the n-type doping concentration of the first wide bandgap sub-layer 121b and / or the third wide bandgap sub-layer 123b is too high, the film quality of the stress release structure 12 is likely to deteriorate, and the film quality in the active structure 14 formed on the stress release structure 12 may also deteriorate. Therefore, the n-type doping concentration in the stress release structure 12 is less than the n-type doping concentration in the n-type nitride semiconductor structure 8, and preferably the n-type doping concentration of the stress release structure 12 is 1 / 10 of the n-type doping concentration in the n-type nitride semiconductor structure 8.

[0096] As Figure 1 and Figure 2 shown, the active structure 14 is disposed on the stress release structure 12. Figure 5 is a schematic structural view of the active structure 14. The active structure 14 is formed by alternately stacking a plurality of quantum well layers 14W and a plurality of barrier layers 14B for several cycles. The thickness of one cycle is the sum of the thickness of one quantum well layer 14W and the thickness of one barrier layer 14B. The thickness of the barrier layer 14B is 2 to 10 times the thickness of the quantum well layer 14W. Specifically, the quantum well layer 14W has a thickness between 2 nm and 4 nm, the barrier layer 14B has a thickness between 4 nm and 40 nm, preferably between 6 nm and 20 nm. The bandgap of the barrier layer 14B is greater than the bandgap of the quantum well layer 14W. The quantum well layer 14W contains indium (In), such as Al s7 In t7 Ga (1-s7-t7) N (0≤s7≤1, 0<t7≤1), preferably In t7 Ga (1-t7)N(0 < t7 < 0.25), and more preferably 0.1 < t7 < 0.15. The barrier layer 14B includes a nitride layer in which the composition ratio of indium (In) is lower than that of the indium (In) in the quantum well layer 14W, such as Al s8 In t8 Ga (1-s8-t8) N(0 ≤ s8 ≤ 0.1, 0 ≤ t8 ≤ 0.1), preferably 0 ≤ s8 ≤ 0.08, more preferably 0 ≤ s8 ≤ 0.05. In one embodiment, the barrier layer 14B is, for example, Al s8 Ga (1-s8) N layer, GaN layer, or a stacked structure including Al s8 Ga (1-s8) N layer and GaN layer, where 0 < s8 ≤ 0.05. The number of periods in which the quantum well layer 14W and the barrier layer 14B are alternately stacked can be, for example, 2 to 20, preferably 3 to 15, more preferably 4 to 12. If the number of periods is too large, the thickness of the active structure 14 will be too thick, the epitaxial quality will decline, and the light emission efficiency of the LED will be reduced. If the number of periods is too small, the thickness of the active structure 14 will be too thin, and the recombination of electrons and holes cannot be effectively achieved, thereby reducing the light emission efficiency of the LED. As Figure 2 shown, the active structure 14 has a total thickness between 100 nm and 200 nm, greater than the total thickness of the stress release structure 12 but less than the total thickness of the periodic structure 10.

[0097] In this embodiment, the narrow bandgap layer 12A of the stress release structure 12 includes In t5 Ga (1-t5) N(0 < t5 ≤ 0.1), and the quantum well layer 14W of the active structure 14 includes In t7 Ga (1-t7) N(0.1 < t7 < 0.15). By using the narrow bandgap layer 12A of the stress release structure 12 with a lower indium (In) composition to make the epitaxial lattice smoothly transition to the active structure 14, the diffusion effect of electrons is further improved, and the light emission efficiency is enhanced.

[0098] Figure 6 is a secondary ion mass spectrometry (SIMS) diagram of the light emitting element 1 according to an embodiment of the present invention. Figure 6 The horizontal axis of corresponds to the distance from the upper surface of the epitaxial structure of the light emitting element 1, for example, the upper surface of the contact layer 18. The closer to the left side of the figure, the closer to the upper surface of the epitaxial structure of the light emitting element 1, and the closer to the right side of the figure, the farther from the upper surface of the epitaxial structure of the light emitting element 1. Figure 6 On the vertical axis of , "1E+M" represents "1×10 MThe left side of the vertical axis represents the concentration of impurities, such as elements C, H, O, Si, and Mg. The right side represents the ionic strength, that is, the relative strength or relative size of elements aluminum (Al) and indium (In), but not a quantitative composition. The relative strength of elements aluminum (Al) and indium (In) on the SIMS diagram can be used to determine the average relative size of the aluminum (Al) and indium (In) composition of each layer. The average composition of each element will be described below. The periodic position of the indium (In) content in the periodic structure 10 is the first semiconductor layer 10A and the second semiconductor layer 10B. The indium (In) content of the first semiconductor layer 10A is higher than that of the second semiconductor layer 10B. The first semiconductor layer 10A and the second semiconductor layer 10B are stacked alternately to form a periodic structure 10 with a period number of 6. The periodic position of the indium (In) content in the stress relief structure 12 is the narrow The bandgap layer 12A and the wide bandgap layer 12B have alternating stacked in a stress-relieving structure 12 with a period of 6. The indium (In) content of the narrow bandgap layer 12A is higher than that of the wide bandgap layer 12B. The indium (In) content of the active structure 14 changes periodically between the quantum well layer 14W and the barrier layer 14B. The indium (In) content of the quantum well layer 14W is higher than that of the barrier layer 14B. The alternating stacked indium well layer 14W and the barrier layer 14B form an active structure 14 with a period of 10. The rate of change in indium (In) composition measured by a secondary ion mass spectrometer can distinguish the quantum well layer 14W and the barrier layer 14B of the active structure 14, the narrow bandgap layer 12A and the wide bandgap layer 12B of the stress-relieving structure 12, and the first semiconductor layer 10A and the second semiconductor layer 10B of the periodic structure 10. Figure 6 As shown, the quantum well layer 14W of the active structure 14, the narrow bandgap layer 12A of the stress relief structure 12, and the first semiconductor layer 10A of the periodic structure 10 have different indium (In) ion intensities. In other words, the indium (In) ion intensity of the quantum well layer 14W of the active structure 14 is relatively greater than that of the narrow bandgap layer 12A of the stress relief structure 12, and the indium (In) ion intensity of the narrow bandgap layer 12A of the stress relief structure 12 is relatively greater than that of the first semiconductor layer 10A of the periodic structure 10. Therefore, the average indium (In) composition of the quantum well layer 14W of the active structure 14 is greater than that of the narrow bandgap layer 12A of the stress relief structure 12, and the average indium (In) composition of the narrow bandgap layer 12A of the stress relief structure 12 is greater than that of the first semiconductor layer 10A of the periodic structure 10.

[0099] Figure 7 This is an energy dispersive X-ray spectrum (EDX) of a light-emitting element 1 according to an embodiment of the present invention. Figure 7The horizontal axis corresponds to the distance from the upper surface of the epitaxial structure of the light-emitting element 1. The closer to the left side of the figure, the closer to the upper surface of the epitaxial structure of the light-emitting element 1. The closer to the right side of the figure, the farther away from the upper surface of the epitaxial structure of the light-emitting element 1. Figure 7 The vertical axis represents the absolute percentage of the element composition, such as the absolute percentage of aluminum (Al) and indium (In). The positions where the indium (In) content and aluminum (Al) content of the stress relief structure 12 periodically change are the positions of the narrow bandgap layer 12A and the wide bandgap layer 12B. The indium (In) content of the narrow bandgap layer 12A is higher than that of the wide bandgap layer 12B, and the aluminum (Al) content of the wide bandgap layer 12B is higher than that of the narrow bandgap layer 12A. The narrow bandgap layer 12A and the wide bandgap layer 12B are stacked alternately to form a stress relief structure 12 with a period of 6. The periodic variations in indium (In) and aluminum (Al) content in the active structure 14 correspond to the positions of the quantum well layer 14W and the barrier layer 14B. The indium (In) content in the quantum well layer 14W is higher than that in the barrier layer 14B, while the aluminum (Al) content in the barrier layer 14B is higher than that in the quantum well layer 14W. The quantum well layer 14W and the barrier layer 14B are alternately stacked to form an active structure 14 with a period of 10. The quantum well layer 14W and the barrier layer 14B of the active structure 14, as well as the narrow bandgap layer 12A and the wide bandgap layer 12B of the stress-relieving structure 12, can be identified by measuring the rate of change of indium (In) or aluminum (Al) content using energy-dispersive X-ray spectroscopy (EDX). Figure 7 As shown, the absolute indium (In) composition of the quantum well layer 14W of the active structure 14 is greater than the absolute indium (In) composition of the narrow bandgap layer 12A of the stress-relieving structure 12.

[0100] The plurality of quantum well layers 14W includes a first quantum well layer 14W1 and a second quantum well layer 14W2. The plurality of barrier layers 14B includes a first barrier layer 14B1 and a second barrier layer 14B2. For example... Figure 5As shown, to identify each quantum well layer 14W and each barrier layer 14B, these layers are numbered as first quantum well layer 14W1, first barrier layer 14B1, second quantum well layer 14W2, second barrier layer 14B2, etc., from the direction from the n-type nitride semiconductor structure 8 toward the p-type nitride semiconductor structure 17. In one growth direction of the active structure 14, the period formed by the first quantum well layer 14W1 and the first barrier layer 14B1, and the period formed by the second quantum well layer 14W2 and the second barrier layer 14B2 are illustrated here as one, but are not limited to the number shown in the figure. For example, the period formed by the first quantum well layer 14W1 and the first barrier layer 14B1 can be configured to be two or more, and multiple first quantum well layers 14W1 and multiple first barrier layers 14B1 can be alternately stacked to form a first group of active structures 14. The period formed by the second quantum well layer 14W2 and the second barrier layer 14B2 can be configured to be more than two, and multiple second quantum well layers 14W2 and multiple second barrier layers 14B2 can be stacked alternately to form a second set of active structures 14.

[0101] In this embodiment, the first quantum well layer 14W1 and the second quantum well layer 14W2 may contain substantially the same thickness and / or indium (In) absolute composition. When each quantum well layer 14W contains the same thickness and / or indium (In) absolute composition, it is advantageous to reduce the full width at half maximum (FWHM) of the LED, which is preferred for light-emitting elements used for specific applications such as lighting. In another embodiment, when the multiple quantum well layers 14W contain different thicknesses and / or indium (In) absolute compositions, it is advantageous to increase the full width at half maximum (FWHM) of the LED, which is preferred for light-emitting elements used for specific applications such as displays.

[0102] If the thickness of the quantum well layer 14W is too small, it will affect the effective recombination of electrons and holes in the quantum well layer 14W, resulting in a decrease in the luminous efficiency of the LED. If the thickness of the quantum well layer 14W is too large, it may cause stress due to the excessive thickness, reducing the epitaxial quality and also affecting the recombination efficiency of electrons and holes, thus affecting the luminous efficiency of the LED. Preferably, the thickness of each quantum well layer 14W is equal to facilitate actual growth control. Figure 2 and Figure 5 As shown, the first barrier layer 14B1 and the second barrier layer 14B2 may have substantially the same thickness. In another embodiment, the thickness of the first barrier layer 14B1 may be greater than the thickness of the second barrier layer 14B2 to increase the recombination efficiency of electrons and holes. The thickness difference between the first barrier layer 14B1 and the second barrier layer 14B2 is maintained within 10% of the thickness of the second barrier layer 14B2.

[0103] The thicknesses of the multiple barrier layers 14B gradually decrease along the growth direction of the active structure 14. Compared with the first barrier layer 14B1 far from the p-type nitride semiconductor structure 17, the thickness of the second barrier layer 14B2 closer to the p-type nitride semiconductor structure 17 is smaller, enabling holes to be more easily injected into the quantum well layer 14W, thereby increasing the transport efficiency of holes within the quantum well layer 14W, improving the distribution uniformity of holes within the quantum well layer 14W, enhancing the radiative recombination efficiency of electrons and holes, and thus improving the light-emitting efficiency of the LED. In this embodiment, the thickness of the barrier layer 14B is preferably 6 nm to 15 nm, and the thickness difference between the multiple barrier layers 14B is not greater than 2 nm. If the thickness of the barrier layer 14B is too thin, the epitaxial quality may be reduced due to the overly small thickness of the barrier layer 14B. If the thickness of the barrier layer 14B is too thick, it is likely to affect the migration of electrons and holes, block the recombination of electrons and holes, and thus reduce the light-emitting efficiency of the LED.

[0104] At least one of the multiple barrier layers 14B includes multiple barrier sub-layers. In this embodiment, each of the multiple barrier layers 14B includes multiple barrier sub-layers, such as a first barrier sub-layer 141b, a second barrier sub-layer 142b, and a third barrier sub-layer 143b. At least one barrier sub-layer or each barrier sub-layer in the barrier layer 14B has a thickness greater than the thickness of the quantum well layer 14W. Each barrier sub-layer in the barrier layer 14B has a bandgap greater than the bandgap of the quantum well layer 14W, and at least one barrier sub-layer among the multiple barrier sub-layers of the barrier layer 14B has a bandgap greater than the bandgaps of the other barrier sub-layers. For example, the first barrier sub-layer 141b contains Al s8 Ga (1-s8) N (0 < s8 ≤ 0.05), and the second barrier sub-layer 142b and the third barrier sub-layer 143b contain GaN.

[0105] In an embodiment of the present invention, some of the barrier layers 14B further include a cap layer 144 located between the quantum well layer 14W and the first barrier sub-layer 141b, where the cap layer 144 directly contacts the quantum well layer 14W, and the first barrier sub-layer 141b is located between the cap layer 144 and the second barrier sub-layer 142b. The cap layer 144 can prevent indium (In) within the quantum well layer 14W from detaching due to subsequent epitaxial temperature or gas condition differences, thereby avoiding the deterioration of the surface morphology of the quantum well layer 14W and the phenomenon of shifting towards shorter wavelengths. The bandgap of the first barrier sub-layer 141b is greater than the bandgaps of the second barrier sub-layer 142b, the third barrier sub-layer 143b, and the cap layer 144, respectively. The second barrier sub-layer 142b, the third barrier sub-layer 143b, and the cap layer 144 preferably contain GaN. The first barrier sub-layer 141b contains Al s8 Ga (1-s8)N (0 < s8 < 1), preferably s8 ≤ 0.08, more preferably s8 ≤ 0.05, even more preferably s8 ≤ 0.03.

[0106] In another embodiment, the plurality of barrier layers 14B further includes an intermediate sub-layer (not shown in the figure) located between the cap layer 144 and the first barrier sub-layer 141b. The intermediate sub-layer includes a lattice constant smaller than that of the other sub-layers of the barrier layer 14B and can be formed of a ternary compound semiconductor or a binary compound semiconductor having Al and N, such as AlGaN or AlN. Preferably, the intermediate sub-layer is formed after each quantum well layer 14W, and the thickness of the intermediate sub-layer is adjusted to compensate for the compressive stress of the quantum well layer 14W. The intermediate sub-layer includes a thickness smaller than that of the other sub-layers of the barrier layer 14B, for example

[0107] Figure 2 is a transmission electron microscope (TEM) image of a part of the light-emitting element 1 according to an embodiment of the present invention. When the compositions of adjacent layers are different, the interfaces of the adjacent layers can be distinguished under a transmission electron microscope, and thus the thicknesses of each layer can be measured. In an embodiment of the present invention, the film thicknesses of each layer and each sub-layer of the stress release structure 12 and the film thicknesses of each layer and each sub-layer of the active structure 14 can be measured by a transmission electron microscope (TEM), and then the absolute aluminum (Al) composition of each sub-layer can be detected by energy dispersive X-ray spectroscopy (EDX), and the relative magnitude relationship of the average aluminum (Al) composition of each layer can be detected under a secondary ion mass spectrometer (SIMS).

[0108] The definition of the average aluminum (Al) composition will be described below by taking the wide bandgap layer 12B of the stress release structure 12 as an example, as Figure 4 shown, the wide bandgap layer 12B includes a first wide bandgap sub-layer 121b, a second wide bandgap sub-layer 122b, and a third wide bandgap sub-layer 123b. In one embodiment, the first wide bandgap sub-layer 121b and the third wide bandgap sub-layer 123b include GaN. The second wide bandgap sub-layer 122b includes Al s6 Ga (1-s6) N. For the sake of simplicity of description, first, the thicknesses of each layer of the first wide bandgap sub-layer 121b, the second wide bandgap sub-layer 122b, and the third wide bandgap sub-layer 123b of the stress release structure 12 measured under a transmission electron microscope (TEM) are respectively defined as T a , T b , and T cSince the second wide bandgap sublayer 122b contains aluminum, while the first wide bandgap sublayer 121b and the third wide bandgap sublayer 123b do not, the absolute aluminum (Al) composition of the wide bandgap layer 12B detected by energy-dispersive X-ray spectroscopy (EDX) is defined as s6, that is, the aluminum composition of the second wide bandgap sublayer 122b is s6. The average aluminum (Al) composition A of the wide bandgap layer 12B can then be defined by the following formula. Based on the thickness T of the second wide bandgap sublayer 122b... b The total thickness of the wide bandgap layer 12B (i.e., thickness T) a Thickness T b and thickness T c The ratio between the sum of the two values, the average aluminum (Al) composition of the wide bandgap layer 12B and the absolute aluminum (Al) composition of the wide bandgap layer 12B are given by the ratio of the sum of the two values. s6 Ga (1-s6) The product of the N film thickness ratio.

[0109]

[0110] The following example, using the wide bandgap layer 12B of the stress-relieving structure 12 (not shown in the figure), illustrates the definition of the average aluminum (Al) composition. Figure 4 As shown, the wide bandgap layer 12B includes a first wide bandgap sublayer 121b, a second wide bandgap sublayer 122b, and a third wide bandgap sublayer 123b. The first wide bandgap sublayer 121b contains Al. x6 Ga (1-x6) N, the second wide bandgap sublayer 122b contains Al s6 Ga (1-s6) N, and the third wide bandgap sublayer 123b contains Al y6 Ga (1-y6) N. To simplify the explanation, firstly, the thicknesses of the first wide bandgap sublayer 121b, the second wide bandgap sublayer 122b, and the third wide bandgap sublayer 123b of the stress relief structure 12, measured under a transmission electron microscope (TEM), are defined as thickness T. A Thickness T B and thickness T C The absolute aluminum (Al) compositions of the first wide bandgap sublayer 121b, the second wide bandgap sublayer 122b, and the third wide bandgap sublayer 123b, as determined by energy-dispersive X-ray spectroscopy, are x6, s6, and y6, respectively. Based on the analysis of the energy-dispersive X-ray spectra and the film thicknesses of each sublayer measured by transmission electron microscopy, the average aluminum (Al) composition P of the wide bandgap layer 12B is obtained using the following formula. The thickness T of each wide bandgap sublayer 121b–123b is then used as a basis for further calculations. A T B , and T C The total thickness of the wide bandgap layer 12B (i.e., thickness T)a , the thickness T b , and the thickness T c The average aluminum (Al) composition of the wide bandgap layer 12B satisfies the following formula with respect to the ratio between the sum of

[0111]

[0112] As Figure 6 shown, the detection result of a Secondary Ion Mass Spectrometer (SIMS) can qualitatively determine that the average aluminum composition contained in the wide bandgap layer 12B is greater than the average aluminum composition contained in the barrier layer 14B. The average aluminum compositions contained in the wide bandgap layer 12B and the barrier layer 14B can be quantitatively obtained through the above formula. As Figure 7 shown, the absolute aluminum composition of the second wide bandgap sublayer 122b containing Al s6 Ga (1-s6) N in the wide bandgap layer 12B is greater than or equal to the absolute aluminum composition of the first barrier sublayer 141b containing Al s8 Ga (1-s8) N in the barrier layer 14B.

[0113] In this embodiment, the wide bandgap layer 12B includes a first wide bandgap sublayer 121b, a second wide bandgap sublayer 122b, and a third wide bandgap sublayer 123b, where the second wide bandgap sublayer 122b containing Al s6 Ga (1-s6) N is located between the first wide bandgap sublayer 121b containing GaN and the third wide bandgap sublayer 123b. As Figure 7 shown, the second wide bandgap sublayer 122b containing Al s6 Ga (1-s6) N is approximately located at the central position between two adjacent narrow bandgap layers 12A.

[0114] In this embodiment, the barrier layer 14B includes a first barrier sublayer 141b, a second barrier sublayer 142b, and a third barrier sublayer 143b, where the first barrier sublayer 141b containing AlGaN is closer to the quantum well layer 14W containing InGaN than the second barrier sublayer 142b and the third barrier sublayer 143b containing GaN, as Figure 7 shown.

[0115] In an embodiment of the present invention, as Figure 4 and Figure 5 shown, the wide bandgap layer 12B of the stress relief structure 12 contains Al s6 Ga (1-s6) N (0 < s6 ≤ 0.05), and the barrier layer 14B of the active structure 14 contains Als8 Ga (1-s8) N (0 < s8 ≤ 0.05). The wide bandgap layer 12B includes a first wide bandgap sub-layer 121b, a second wide bandgap sub-layer 122b, and a third wide bandgap sub-layer 123b. The one containing Al s6 Ga (1-s6) The film thickness of the second wide bandgap sub-layer 122b containing N has a first film thickness ratio with respect to the film thickness of the wide bandgap layer 12B. The barrier layer 14B includes a first barrier sub-layer 141b, a second barrier sub-layer 142b, and a third barrier sub-layer 143b. The one containing Al s8 Ga (1-s8) The film thickness of the first barrier sub-layer 141b containing N has a second film thickness ratio with respect to the film thickness of the barrier layer 14B. As Figure 7 shown, when the wide bandgap layer 12B contains Al s6 Ga (1-s6) The absolute aluminum (Al) composition of the second wide bandgap sub-layer 122b of N is equal to that of the first barrier sub-layer 141b containing Al in the barrier layer 14B s8 Ga (1-s8) N, that is, when the absolute aluminum (Al) composition s6 of the second wide bandgap sub-layer 122b is the same as the absolute aluminum (Al) composition s8 of the first barrier sub-layer 141b, the first film thickness ratio is preferably greater than the second film thickness ratio, so that the average aluminum (Al) composition of the wide bandgap layer 12B is greater than the average aluminum (Al) composition of the barrier layer 14B, which can be assisted by Figure 6 shown for judgment. In the energy dispersive X-ray spectrogram, when the absolute aluminum (Al) composition of the second wide bandgap sub-layer 122b of the wide bandgap layer 12B is greater than the absolute aluminum (Al) composition of the first barrier sub-layer 141b of the barrier layer 14B, the first film thickness ratio can also be greater than or equal to the second film thickness ratio, so that the average aluminum (Al) composition of the wide bandgap layer 12B is greater than the average aluminum (Al) composition of the barrier layer 14B, and it can also be assisted by the secondary ion mass spectrometry diagram for judgment.

[0116] In an embodiment of the present invention, as Figure 1 and Figure 5As shown, the first barrier layer 14B1 is closer to the stress relief structure 12 than the second barrier layer 14B2. The first barrier layer 14B1 includes a first barrier sublayer 141b1, a second barrier sublayer 142b1, and a third barrier sublayer 143b1. The second barrier layer 14B2 includes a first barrier sublayer 141b2, a second barrier sublayer 142b2, and a third barrier sublayer 143b2. When the thickness of the first barrier layer 14B1 is greater than the thickness of the second barrier layer 14B2, for example, the thickness of any one or more barrier sublayers of the first barrier layer 14B1 may be greater than the thickness of any one or more barrier sublayers of the second barrier layer 14B2. In one embodiment, the thickness of the first barrier sublayer 141b1 of the first barrier layer 14B1 is greater than the thickness of the first barrier sublayer 141b2 of the second barrier layer 14B2, the thickness of the second barrier sublayer 142b1 of the first barrier layer 14B1 is approximately the same as the thickness of the second barrier sublayer 142b2 of the second barrier layer 14B2, and the thickness of the third barrier sublayer 143b1 of the first barrier layer 14B1 is approximately the same as the thickness of the third barrier sublayer 143b2 of the second barrier layer 14B2. Preferably, the composition and absolute aluminum (Al) composition of the first barrier sublayer 141b1 of the first barrier layer 14B1 can be the same as the composition and absolute aluminum (Al) composition of the first barrier sublayer 141b2 of the second barrier layer 14B2, the composition of the second barrier sublayer 142b1 of the first barrier layer 14B1 is the same as the composition of the second barrier sublayer 142b2 of the second barrier layer 14B2, and the composition of the third barrier sublayer 143b1 of the first barrier layer 14B1 is the same as the composition of the third barrier sublayer 143b2 of the second barrier layer 14B2. Furthermore, the average aluminum (Al) composition of the first barrier layer 14B1 closer to the stress relief structure 12 can be greater than the average aluminum (Al) composition of the second barrier layer 14B2 farther from the stress relief structure 12. Figure 6 and Figure 7 As shown.

[0117] In one embodiment of the present invention, such as Figure 4As shown, the first wide bandgap layer 12B1 includes a first wide bandgap sublayer 121b1, a second wide bandgap sublayer 122b1, and a third wide bandgap sublayer 123b1. The second wide bandgap layer 12B2 includes a first wide bandgap sublayer 121b2, a second wide bandgap sublayer 122b2, and a third wide bandgap sublayer 123b2. When the thickness of the second wide bandgap layer 12B2 is greater than the thickness of the first wide bandgap layer 12B1, for example, the thickness of any one or more sublayers of the second wide bandgap layer 12B2 may be greater than the thickness of any one or more sublayers of the first wide bandgap layer 12B1. In one embodiment, the thickness of the second wide bandgap sublayer 122b2 of the second wide bandgap layer 12B2 is greater than the thickness of the second wide bandgap sublayer 122b1 of the first wide bandgap layer 12B1, but the thickness of the first wide bandgap sublayer 121b1 of the first wide bandgap layer 12B1 is approximately the same as the thickness of the first wide bandgap sublayer 121b2 of the second wide bandgap layer 12B2, and / or the thickness of the third wide bandgap sublayer 123b1 of the first wide bandgap layer 12B1 is approximately the same as the thickness of the third wide bandgap sublayer 123b2 of the second wide bandgap layer 12B2. Preferably, the absolute aluminum (Al) composition of the second wide bandgap sublayer 122b2 containing AlGaN in the second wide bandgap layer 12B2 can be greater than or equal to the absolute aluminum (Al) composition of the second wide bandgap sublayer 122b1 containing AlGaN in the first wide bandgap layer 12B1, such as... Figure 7 As shown. The composition of the first wide bandgap sublayer 121b1 of the first wide bandgap layer 12B1 is the same as that of the first wide bandgap sublayer 121b2 of the second wide bandgap layer 12B2, and the composition of the third wide bandgap sublayer 123b1 of the first wide bandgap layer 12B1 is the same as that of the third wide bandgap sublayer 123b2 of the second wide bandgap layer 12B2. Furthermore, the average aluminum (Al) composition of the second wide bandgap layer 12B2 is greater than that of the first wide bandgap layer 12B1, as shown. Figure 6 As shown.

[0118] like Figure 5As shown, the first barrier sublayer 141b, the second barrier sublayer 142b, and the third barrier sublayer 143b each have a thickness greater than 1 nm but less than 5 nm. The capping layer 144 has a thickness of no more than 1 nm. Compared to the thicknesses of the first barrier sublayer 141b, the second barrier sublayer 142b, and the third barrier sublayer 143b, the capping layer 144 is very thin. The thickness of the first barrier sublayer 141b and the thickness of the barrier layer 14B have a second thickness ratio between 35% and 45%. In this embodiment, the second thickness ratio of the first barrier sublayer 141b to the barrier layer 14B in the active structure 14 can be less than or approximately the same as the first thickness ratio of the second wide bandgap sublayer 122b to the wide bandgap layer 12B in the stress-relieving structure 12. The sum of the thickness of the first barrier sublayer 141b and the thickness of the capping layer 144 is less than the sum of the thickness of the second barrier sublayer 142b and the thickness of the third barrier sublayer 143b.

[0119] In this embodiment, the first barrier sublayer 141b is closer to the n-type nitride semiconductor structure 8 than the second barrier sublayer 142b, the second barrier sublayer 142b is closer to the n-type nitride semiconductor structure 8 than the third barrier sublayer 143b, and the third barrier sublayer 143b is closer to the n-type nitride semiconductor structure 8 than the capping layer 144. The third barrier sublayer 143b and the capping layer 144 respectively contact two opposite sides of the quantum well layer 14W. The capping layer 144 can alleviate the stress and defects caused by lattice mismatch between the first barrier sublayer 141b and the quantum well layer 14W.

[0120] Because electrons have a higher mobility than holes, electrons and holes typically recombine in the quantum well layer 14W closer to the p-type nitride semiconductor structure 17. Doping the barrier layer 14B with n-type impurities can improve electron injection efficiency, thereby reducing the forward voltage of the light-emitting element 1. One of the first barrier sublayer 141b, the second barrier sublayer 142b, and the third barrier sublayer 143b may contain a relatively high concentration of n-type impurities, preferably the third barrier sublayer 143b. The others of the first barrier sublayer 141b, the second barrier sublayer 142b, and the third barrier sublayer 143b may be doped with a relatively low concentration of n-type impurities or be undoped. In one embodiment of the invention, at least one of the first barrier sublayer 141b, the second barrier sublayer 142b, the third barrier sublayer 143b, and the capping layer 144 contains an n-type impurity, which comprises silicon (Si), carbon (C), or germanium (Ge), preferably silicon (Si). The concentration of n-type impurities is preferably less than 1 × 10⁻⁶. 18 cm -3 But greater than or equal to 1×10 17 cm -3When the n-type impurity concentration is too low, due to the reduction in the number of carriers, polarization occurs, resulting in an increase in the operating voltage and a decrease in the light-emitting efficiency. When the n-type impurity concentration is too high, the epitaxial quality is also affected due to the excessive impurity concentration, leading to a decrease in the light-emitting efficiency.

[0121] In an embodiment of the present invention, the second barrier layer 14B2 closer to the p-type nitride semiconductor structure 17 has a relatively thinner thickness than the first barrier layer 14B1 farther from the p-type nitride semiconductor structure 17. By doping silicon (Si) into the barrier layer 14B of the active structure 14 to improve the electron mobility, and the doping concentration of silicon (Si) increases from the direction closer to the n-type nitride semiconductor structure 8 to the direction farther from the n-type nitride semiconductor structure 8. In other words, the silicon (Si) doping concentration of the second barrier layer 14B2 closer to the p-type nitride semiconductor structure 17 is higher than that of the first barrier layer 14B1 farther from the p-type nitride semiconductor structure 17 to make the electron distribution in the barrier layer 14B uniform, increase the mobility of electrons and holes in the active structure 14, enable more holes and electrons to radiatively recombine and emit light in the active structure 14, and improve the light-emitting efficiency of the LED. The doping concentration of silicon (Si) is preferably 5×10 17 ~1×10 18 cm -3 ⁻³, and doping an appropriate amount of silicon (Si) into the multiple barrier layers 14B can also reduce the defects of the active structure 14, improve the epitaxial quality of the active structure 14, and thus further improve the light-emitting efficiency of the LED.

[0122] In this embodiment, the n-type impurity concentration of the wide-bandgap layer 12B of the stress relief structure 12 is 45% - 60% of the n-type impurity concentration of the barrier layer 14B of the active structure. By increasing the n-type impurity concentration of the active structure 14 to increase the electron concentration in the active structure 14, the recombination efficiency of electrons and holes in the active structure 14 and the light-emitting efficiency of the LED are improved.

[0123] The active layer 14 can be directly or indirectly adjacent to the stress relief structure 12. In an embodiment where the active structure 14 is in direct contact with the stress relief structure 12, the active structure 14 can be in contact with the narrow-bandgap layer 12A of the stress relief structure 12 through the first barrier sublayer 141b, the second barrier sublayer 142b, or the third barrier sublayer 143b of the barrier layer 14B. For example, the first barrier sublayer 141b containing Al s8 Ga (1-s8) N(0 < s8 < 1) can be in contact with the narrow-bandgap layer 12A of the stress relief structure 12. In another embodiment, the active structure 14 can be in contact with the wide-bandgap layer 12B of the stress relief structure 12 through the quantum well layer 14W.

[0124] In this embodiment, a final barrier layer 14LB is provided on the active structure 14 and is located between the electron blocking structure 16 and the active structure 14. The final barrier layer 14LB contains n-type impurities, and the n-type impurities are preferably silicon (Si), carbon (C), or germanium (Ge), and more preferably silicon (Si). The n-type impurity concentration is preferably less than 5×10 17 cm -3 , but less than or equal to 1×10 17 cm -3 . The final barrier layer 14LB may contain indium (In) to block electrons, such as Al s9 In t9 Ga (1-s9-t9) N (0 ≤ s9 ≤ 1, 0 < t9 ≤ 1), preferably In t9 Ga (1-t9) N (0 < t9 < 1), and more preferably 0.002 < t9 < 0.02. In one embodiment, the indium (In) content of the quantum well layer 14W is greater than the indium (In) content of the narrow bandgap layer 12A, and the indium (In) content of the narrow bandgap layer 12A may be greater than the indium (In) content of the final barrier layer 14LB.

[0125] Due to the thermal diffusion effect during the growth of the p-type nitride semiconductor structure 17, it can be observed by secondary ion mass spectrometry that the stress relief structure 12, the active structure 14, and / or the final barrier layer 14LB contain p-type impurities with a concentration greater than 1×10 17 cm -3 , such as magnesium (Mg), as Figure 1 and Figure 6 shown.

[0126] As Figure 1 shown, the electron blocking structure 16 is provided between the active structure 14 and the p-type nitride semiconductor structure 17, blocks electrons from overflowing from the active structure 14 to the p-type nitride semiconductor structure 17, and allows holes to be injected into the active structure 14 to improve the light emission efficiency of the light emitting element 1. The material of the electron blocking structure 16 has a higher bandgap than the p-type nitride semiconductor structure 17, and the bandgap of the electron blocking structure 16 decreases in the direction towards the p-type nitride semiconductor structure 17. The electron blocking structure 16 may include or not include aluminum indium gallium nitride (AlInGaN), aluminum gallium nitride (AlGaN), and / or aluminum nitride (AlN) with p-type impurities, such as Al s10 In t10 Ga (1-s10-t10) N (0 ≤ s10 ≤ 1, 0 < t10 ≤ 0.05), preferably Al s10 Ga (1-s10)N (0 < s10 < 1), and more preferably 0.05 < s10 ≤ 0.5. The thickness of the electron blocking structure 16 can be 10 nm to 100 nm, preferably 20 nm to 80 nm, and more preferably 30 nm to 60 nm. The electron blocking structure 16 can be a single layer or include multiple layers. As Figure 6 shown, the average aluminum (Al) composition of the electron blocking structure 16 is greater than the average aluminum (Al) composition of the active structure 14, and greater than the average aluminum (Al) composition of the stress relief structure 12. As Figure 7 shown, the absolute aluminum (Al) composition of the electron blocking structure 16 is greater than the absolute aluminum (Al) composition of any layer of the active structure 14, and greater than the absolute aluminum (Al) composition of any layer of the stress relief structure 12.

[0127] In one embodiment, the electron blocking structure 16 can be doped with a p-type impurity such as magnesium (Mg), and the p-type doping concentration of the electron blocking structure 16 decreases in the direction toward the active structure 14. The doping concentration of the p-type impurity in the electron blocking structure 16 can be lower than the doping concentration of the p-type impurity in the p-type nitride semiconductor structure 17. The p-type impurity concentration in the electron blocking structure 16 is preferably greater than or equal to 1×10 19 cm -3 , and more preferably greater than or equal to 1×10 20 cm -3 , as Figure 6 shown.

[0128] The p-type nitride semiconductor structure 17 can include a multi-layer structure composed of a p-type AlGaN layer and / or a p-type GaN layer, or a single-layer structure composed of a p-type AlGaN layer or a p-type GaN layer. The p-type nitride semiconductor structure 17 contains Al s11 In t11 Ga (1-s11-t11) N (0 ≤ s11 ≤ 1, 0 < t11 ≤ 1), preferably Al [[ID=2']] s11 Ga (1-s11) N (0 < s11 < 0.2), and more preferably 0.01 < s11 < 0.05. The absolute aluminum (Al) composition in the p-type nitride semiconductor structure 17 is less than the absolute aluminum (Al) composition in the electron blocking structure z6. If the aluminum (Al) content in the p-type nitride semiconductor structure 17 is too high, it will increase the driving voltage of the light-emitting element 1. The p-type impurity is, for example, magnesium (Mg), but is not particularly limited to magnesium (Mg). The p-type impurity concentration in the p-type nitride semiconductor structure 17 is preferably greater than or equal to 1×10 19 cm -3 , and more preferably greater than or equal to 1×10 20 cm -3 , as Figure 6 shown.

[0129] The thickness of the p-type nitride semiconductor structure 17 is preferably but not limited to be greater than or equal to 50 nm and less than or equal to 300 nm. By reducing the thickness of the p-type nitride semiconductor structure 17, the heating time during growth can be reduced and the diffusion of p-type impurities into the active structure 14 can be inhibited.

[0130] The contact layer 18 is formed on the p-type nitride semiconductor structure 17 to form an ohmic contact with the transparent conductive layer 23 described below. The contact layer 18 contains n-type impurities or p-type impurities. The n-type impurities are preferably silicon (Si), carbon (C), or germanium (Ge), and more preferably silicon (Si). The p-type impurities are preferably magnesium (Mg). The concentration of the n-type impurities or p-type impurities is preferably greater than 5×10 19 cm -3 , and more preferably greater than or equal to 1×10 20 cm -3 . The contact layer 18 has a thickness less than or equal to 10 nm but at least greater than 0.1 nm. The contact layer 18 is a single-layer structure, such as Al s12 In t12 Ga (1-s12-t12) N(0≤s12≤1, 0≤t12≤1), preferably Al s12 Ga (1-s12) N(0 < s12 < 1), and more preferably 0.03≤s12≤0.3.

[0131] The transparent conductive layer 23 contains a transparent oxide as an ohmic contact layer. In order to reduce the contact resistance and improve the efficiency of current diffusion, the material of the transparent oxide contains a material that is transparent to the light emitted by the active layer. The transparent conductive layer 23 contains at least one of indium tin oxide (ITO), zinc oxide (ZnO), zinc indium tin oxide (ZITO), zinc indium oxide (ZIO), zinc tin oxide (ZTO), gallium indium tin oxide (GITO), gallium indium oxide (GIO), gallium zinc oxide (GZO), aluminum doped zinc oxide (AZO), fluorine tin oxide (FTO) and other light-transmitting conductive oxides, and a light-transmitting metal layer with a thickness less than 500 Å such as aluminum (Al), nickel (Ni), or gold (Au). The light-transmitting conductive oxide may also include various dopants.

[0132] The insulating layer 27 can be a single-layer structure, composed of silicon oxide, silicon nitride, or silicon oxynitride. The insulating layer 27 can also contain two or more materials with different refractive indices stacked alternately to form a distributed Bragg reflector (DBR) structure that selectively reflects light of specific wavelengths. For example, a highly reflective insulating reflective structure can be formed by stacking layers such as SiO2 / TiO2 or SiO2 / Nb2O5. When SiO2 / TiO2 or SiO2 / Nb2O5 forms a distributed Bragg reflector (DBR) structure, each layer of the DBR structure is designed to have an optical thickness that is one or an integer multiple of one-quarter of the wavelength of light emitted by the active structure 14. The optical thickness of each layer of the DBR structure can have a deviation of ±30% based on one or an integer multiple of λ / 4. Since the optical thickness of each layer of the DBR structure affects the reflectivity, electron beam evaporation is preferably used to stably control the thickness of each layer of the DBR structure.

[0133] The n-side electrode 21 and p-side electrode 25 comprise metallic materials, such as chromium (Cr), titanium (Ti), tungsten (W), gold (Au), aluminum (Al), indium (In), tin (Sn), nickel (Ni), platinum (Pt), silver (Ag), or alloys thereof. The n-side electrode 21 and p-side electrode 25 can be composed of a single layer or multiple layers. For example, the n-side electrode 21 and p-side electrode 25 may include a Ti / Au layer, a Ti / Pt / Au layer, a Cr / Au layer, a Cr / Pt / Au layer, a Ni / Au layer, a Ni / Pt / Au layer, a Cr / Al / Cr / Ni / Au layer, or an Ag / NiTi / TiW / Pt layer. The n-side electrode 21 and p-side electrode 25 can serve as external power sources supplying current to the n-type nitride semiconductor structure 8 and the p-type nitride semiconductor structure 17. The n-side electrode 21 and the p-side electrode 25 each have a thickness between 1 and 100 μm, preferably between 1.2 and 60 μm, and more preferably between 1.5 and 6 μm.

[0134] Figure 8 This is a schematic diagram of a light-emitting device 2 according to an embodiment of the present invention. The light-emitting element 1 from the aforementioned embodiment is mounted as a flip chip on a first pad 511 and a second pad 512 of a packaging substrate 51. The first pad 511 and the second pad 512 are electrically insulated from each other by an insulating portion 53 containing insulating material. In flip chip mounting, the growth substrate side facing the electrode pad formation surface is designated as the primary light extraction surface. To increase the light extraction efficiency of the light-emitting device 2, a reflective structure 54 can be provided around the light-emitting element 1.

[0135] Figure 9 This is a schematic diagram of a light-emitting device 3 according to an embodiment of the present invention. The light-emitting device 3 is a bulb lamp including a lampshade 602, a reflector 604, a light-emitting module 611, a lamp holder 612, a heat sink 614, a connecting portion 616, and an electrical connection element 618. The light-emitting module 611 includes a support portion 606, and a plurality of light-emitting units 608 are located on the support portion 606, wherein the plurality of light-emitting units 608 may be the light-emitting element 1 or the light-emitting device 2 in the aforementioned embodiments.

Claims

1. A semiconductor element comprising: n-type nitride semiconductor structure; The stress relief structure, located on the n-type nitride semiconductor structure, comprises multiple narrow bandgap layers and multiple wide bandgap layers stacked alternately, wherein one of the multiple wide bandgap layers comprises a first wide bandgap sublayer and a second wide bandgap sublayer. An active structure, located on the stress-relieving structure, comprises multiple quantum well layers and multiple barrier layers stacked alternately, wherein one of the multiple barrier layers comprises a first barrier sublayer and a second barrier sublayer; An electron blocking structure is located on the active structure; as well as A p-type nitride semiconductor structure is located on this electron blocking structure; Wherein, the absolute aluminum composition of the first wide bandgap sublayer is greater than or equal to the absolute aluminum composition of the first barrier sublayer; and Wherein, the band gap of the first wide band gap sublayer and the second wide band gap sublayer is greater than the band gap of any one of the plurality of narrow band gap layers; The absolute aluminum composition of the first wide bandgap sublayer is greater than that of the second wide bandgap sublayer, and the absolute aluminum composition of the first barrier sublayer is greater than that of the second barrier sublayer.

2. The semiconductor device as claimed in claim 1, wherein, The first wide bandgap sublayer or the second wide bandgap sublayer contains Al x Ga (1-x) N, 0 <x<1。 3. The semiconductor device as claimed in claim 1, wherein, The first wide bandgap sublayer contains Al s6 Ga (1-s6) N, where 0 < s6 < 1, and the second wide bandgap sublayer contains GaN.

4. The semiconductor device as claimed in claim 3, wherein, s6≤0.05。 5. The semiconductor device as claimed in claim 1, wherein, The band gaps of the first barrier sublayer and the second barrier sublayer are greater than the band gaps of any one of the plurality of quantum well layers.

6. The semiconductor device as claimed in claim 1, wherein, The first barrier sub-layer contains Al s8 Ga (1-s8) N, where 0 < s8 < 1, and the second barrier sub-layer contains GaN.

7. The semiconductor device of claim 6, wherein, s8≤0.05。 8. The semiconductor device as claimed in claim 1, wherein, The first thickness ratio of the first wide bandgap sublayer to one of the plurality of wide bandgap layers is greater than the second thickness ratio of the first barrier sublayer to one of the plurality of barrier layers.

9. The semiconductor device as claimed in claim 1, wherein, One of the plurality of narrow bandgap layers contains In t5 Ga (1-t5) N (0 < t5 ≤ 0.1), and one of the plurality of quantum well layers contains In t7 Ga (1-t7) N (0.1 < t7 < 0.15).

10. The semiconductor device of claim 1, wherein, One of the plurality of wide bandgap layers further includes a capping layer with a thickness of no more than 1 nm, and the capping layer is in direct contact with one of the plurality of quantum well layers.

11. The semiconductor device of claim 10, wherein, The capping layer contains GaN.

12. The semiconductor device of claim 1, wherein, The average aluminum composition of the wide bandgap layer is greater than that of the barrier layer.

13. The semiconductor device as claimed in claim 1, wherein, One of the plurality of wide bandgap layers further comprises a third wide bandgap sublayer, which comprises GaN.

14. The semiconductor device of claim 13, wherein, The sum of the thickness of the first wide bandgap sublayer and the thickness of the second wide bandgap sublayer is greater than the thickness of the third wide bandgap sublayer.

15. A semiconductor element comprising: n-type nitride semiconductor structure; An active structure, located on the n-type nitride semiconductor structure, comprises multiple quantum well layers and multiple barrier layers stacked alternately, one of which comprises a first barrier sublayer and an intermediate sublayer; A wide bandgap layer and a narrow bandgap layer are located between the n-type nitride semiconductor structure and the active structure; A p-type nitride semiconductor structure is located on this active structure; as well as Wherein, the average aluminum composition of the wide bandgap layer is greater than or equal to the average aluminum composition of the barrier layer; and The band gap of the first barrier sublayer and the intermediate sublayer is greater than the band gap of any of the plurality of quantum well layers, and the intermediate sublayer contains AlN or AlGaN.

16. The semiconductor device of claim 15, wherein, The intermediate sublayer has a thickness less than that of the first barrier sublayer.

17. The semiconductor device of claim 16, wherein, The thickness of this intermediate sublayer is 1 Å to 30 Å.

18. The semiconductor device of claim 15, wherein, The intermediate sublayer contains a lattice constant that is smaller than that of the first barrier sublayer.

19. The semiconductor device of claim 15, wherein, The plurality of barrier layers also include a capping layer, and the intermediate sublayer is located between the capping layer and the first barrier sublayer.

20. The semiconductor device of claim 15, wherein, One of the plurality of barrier layers further comprises a second barrier sublayer, wherein the bandgap of the first barrier sublayer is greater than that of the second barrier sublayer.

Images