Red light emitting diode epitaxial structure and method of manufacturing the same

Abstract

The application discloses a red light emitting diode epitaxial structure and a manufacturing method thereof. The red light emitting diode epitaxial structure comprises, from bottom to top, a substrate, a first semiconductor layer, a multi-quantum well structure and a second semiconductor layer, the doping types of the first semiconductor layer and the second semiconductor layer are opposite, a first space layer is located between the first semiconductor layer and the multi-quantum well structure, and a second space layer is located between the second semiconductor layer and the multi-quantum well structure, wherein the first space layer and the second space layer are superlattice structures, the first space layer and the second space layer each comprise alternately stacked aluminum phosphorus layers and aluminum gallium indium phosphorus layers. The first space layer and the second space layer in the application can enhance the carrier confinement effect of the multi-quantum well structure, effectively prevent the diffusion of a doping source to the multi-quantum well structure, reduce the non-radiative recombination centers caused by the doping source in the multi-quantum well structure, enhance the crystal quality of the multi-quantum well structure and improve the radiative recombination efficiency.

Description

Technical Field

[0001] This application relates to the field of semiconductor manufacturing technology, and more specifically, to an epitaxial structure of a red light-emitting diode and a method for manufacturing the same. Background Technology

[0002] Existing AlGaInP (AlGaInP) red light-emitting diodes (LEDs) mostly use AlGaInP as the well and barrier layers in a multi-quantum-well structure. Due to the relatively small bandgap of the material itself, the multi-quantum-well structure of AlGaInP has a low confinement effect on charge carriers, leading to easy carrier overflow and a sharp decrease in radiative recombination. On the other hand, dopants from the P-type and N-type semiconductor layers located on both sides of the multi-quantum-well structure can enter the structure and form non-radiative recombination centers, which not only reduce radiative recombination efficiency but also affect the crystal quality of the multi-quantum-well structure.

[0003] Therefore, it is necessary to provide an epitaxial structure for a red light-emitting diode and its fabrication method, which increases the confinement of charge carriers by the multi-quantum-well structure, reduces the entry of doping sources into the multi-quantum-well structure, enhances the crystal quality of the multi-quantum-well structure, and improves the radiative recombination efficiency. Summary of the Invention

[0004] In view of the above problems, the purpose of this disclosure is to provide an epitaxial structure of a red light-emitting diode and its fabrication method, so as to improve the radiative recombination efficiency.

[0005] According to one aspect of the present disclosure, a red light-emitting diode epitaxial structure is provided, comprising: a substrate, a first semiconductor layer, a multiple quantum well structure, and a second semiconductor layer stacked sequentially from bottom to top, wherein the first semiconductor layer and the second semiconductor layer have opposite doping types; a first space layer located between the first semiconductor layer and the multiple quantum well structure; and a second space layer located between the second semiconductor layer and the multiple quantum well structure, wherein the first space layer and the second space layer are superlattice structures, and both the first space layer and the second space layer include alternately stacked aluminum phosphide layers and aluminum gallium indium phosphide layers.

[0006] Optionally, the substrate includes a gallium arsenide substrate, and the structural layers on the two opposite outer surfaces of the first spatial layer are both aluminum gallium indium phosphide layers, and the structural layers on the two opposite outer surfaces of the second spatial layer are both aluminum gallium indium phosphide layers.

[0007] Optionally, the first semiconductor layer is an N-type semiconductor layer, and the second semiconductor layer is a P-type semiconductor layer.

[0008] Optionally, the number of stacked pairs of the second spatial layer is greater than or equal to the number of stacked pairs of the first spatial layer.

[0009] Optionally, the number of stacked pairs in the second spatial layer includes 10 to 13 pairs, and the number of stacked pairs in the first spatial layer includes 7 to 10 pairs.

[0010] Optionally, a portion of the stacked layers in the first spatial layer away from the multi-quantum well structure has doped impurities, and / or a portion of the stacked layers in the second spatial layer away from the multi-quantum well structure has doped impurities.

[0011] Optionally, the number of stacked pairs with doped impurities in the first spatial layer includes 2 to 3 pairs, and the number of stacked pairs with doped impurities in the second spatial layer includes 2 to 3 pairs.

[0012] Optionally, in the first space layer and the second space layer, the thickness of a single aluminum phosphide layer ranges from 0.5 to 1 nm, and the thickness of a single aluminum gallium indium phosphide layer ranges from 9 to 11 nm.

[0013] Optionally, the single-layer aluminum-phosphorus layer comprises 1 to 3 aluminum-phosphorus monolayers.

[0014] Optionally, the material of the multi-quantum well structure includes aluminum gallium indium phosphide, and the aluminum composition of the well layer and the barrier layer in the multi-quantum well structure is less than the aluminum composition of the aluminum gallium indium phosphide layer in the first space layer and the second space layer.

[0015] Optionally, the first semiconductor layer includes a first confinement layer, which is adjacent to the first space layer, and a buffer layer and a mirror layer are further disposed sequentially from bottom to top between the first confinement layer and the substrate.

[0016] Optionally, the first semiconductor layer includes a first ohmic contact layer, a first current spreading layer, and a first confinement layer arranged sequentially from bottom to top, and a buffer layer and an etching stop layer arranged sequentially from bottom to top are further disposed between the first ohmic contact layer and the substrate.

[0017] Optionally, the second semiconductor layer includes a second confinement layer, a second current spreading layer, and a second ohmic contact layer disposed sequentially from bottom to top.

[0018] According to another aspect of the present disclosure, a method for manufacturing a red light-emitting diode epitaxial structure is provided, comprising forming, in sequence from bottom to top, a first semiconductor layer, a first space layer, a multiple quantum well structure, a second space layer and a second semiconductor layer on a substrate, wherein the first semiconductor layer and the second semiconductor layer have opposite doping types, wherein the first space layer and the second space layer are superlattice structures, and both the first space layer and the second space layer include alternating stacked aluminum phosphide layers and aluminum gallium indium phosphide layers.

[0019] Optionally, the substrate includes a gallium arsenide substrate, and the structural layers on the two opposite outer surfaces of the first spatial layer are both aluminum gallium indium phosphide layers, and the structural layers on the two opposite outer surfaces of the second spatial layer are both aluminum gallium indium phosphide layers.

[0020] Optionally, the first semiconductor layer is an N-type semiconductor layer, and the second semiconductor layer is a P-type semiconductor layer.

[0021] Optionally, the number of stacked pairs of the second spatial layer is greater than or equal to the number of stacked pairs of the first spatial layer.

[0022] Optionally, the number of stacked pairs in the second spatial layer includes 10 to 13 pairs, and the number of stacked pairs in the first spatial layer includes 7 to 10 pairs.

[0023] Optionally, a portion of the stacked layers in the first spatial layer away from the multi-quantum well structure has doped impurities, and / or a portion of the stacked layers in the second spatial layer away from the multi-quantum well structure has doped impurities.

[0024] Optionally, the number of stacked pairs with doped impurities in the first spatial layer includes 2 to 3 pairs, and the number of stacked pairs with doped impurities in the second spatial layer includes 2 to 3 pairs.

[0025] Optionally, in the first space layer and the second space layer, the thickness of a single aluminum phosphide layer ranges from 0.5 to 1 nm, and the thickness of a single aluminum gallium indium phosphide layer ranges from 9 to 11 nm.

[0026] Optionally, the single-layer aluminum-phosphorus layer comprises 1 to 3 aluminum-phosphorus monolayers.

[0027] Optionally, the material of the multi-quantum well structure includes aluminum gallium indium phosphide, and the aluminum composition of the well layer and the barrier layer in the multi-quantum well structure is less than the aluminum composition of the aluminum gallium indium phosphide layer in the first space layer and the second space layer.

[0028] Optionally, the first semiconductor layer includes a first confinement layer adjacent to the first space layer, and the manufacturing method further includes forming a buffer layer and a mirror layer sequentially from bottom to top between the first confinement layer and the substrate.

[0029] Optionally, the first semiconductor layer includes a first ohmic contact layer, a first current spreading layer, and a first confinement layer disposed sequentially from bottom to top, and the manufacturing method further includes forming a buffer layer and an etching stop layer sequentially from bottom to top between the first ohmic contact layer and the substrate.

[0030] Optionally, forming the second semiconductor layer includes forming a second confinement layer, a second current spreading layer, and a second ohmic contact layer sequentially from bottom to top on the second space layer.

[0031] According to the epitaxial structure and fabrication method of the red light-emitting diode provided in the embodiments of this disclosure, by setting a first space layer and a second space layer of superlattice structure on both sides (n side and p side) of the multi-quantum well structure, the confinement effect of the multi-quantum well structure on charge carriers (electrons and holes) is enhanced, preventing the overflow of charge carriers, especially electrons. At the same time, it can effectively prevent the diffusion of doping sources into the multi-quantum well structure, reduce the non-radiative recombination centers caused by doping sources in the multi-quantum well structure, enhance the crystal quality of the multi-quantum well structure, and improve the radiative recombination efficiency. Meanwhile, charge carriers can also enter the multi-quantum well structure through the tunneling effect to undergo radiative recombination, thereby improving the photoelectric performance and reliability of the red light-emitting diode.

[0032] Furthermore, the superlattice structures of both the first and second space layers are composed of alternating stacks of aluminum phosphide and aluminum gallium indium phosphide layers. Since the stacks are composed of two different materials, the crystal interface of the superlattice structure is clearer, resulting in better crystal quality.

[0033] In the first space layer, the second space layer, and the multi-quantum well structure, the aluminum gallium indium phosphide (AGaInP) layer in the first and second space layers has a higher aluminum content than the AGaInP layer in the well layer and barrier layer of the multi-quantum well structure. This means that the first and second space layers have a higher bandgap than the multi-quantum well structure, which further enhances the carrier confinement effect, suppresses carrier overflow, and thus enhances the carrier recombination probability, thereby improving the photoelectric efficiency and reliability of the red light-emitting diode.

[0034] Furthermore, since charge carriers diffuse toward the multi-quantum-well structure due to concentration differences, and the diffusion lengths of P-type doping and N-type doping are different, in order to prevent charge carriers from entering the multi-quantum-well structure due to diffusion, the stacking log number of the second spatial layer is set to be greater than or equal to the stacking log number of the first spatial layer, so that the thickness of the second spatial layer is greater than or equal to the thickness of the first spatial layer, thereby maximizing the recombination of electrons and holes in the multi-quantum-well structure to emit light, thus effectively controlling the light field distribution.

[0035] Furthermore, since both the first and second space layers are superlattice structures, the aluminum phosphorus layer, in addition to suppressing carrier overflow, can also prevent doping sources from entering the multi-quantum well structure. The aluminum phosphorus layer is very thin, with only 1 to 3 monolayers, which facilitates the tunneling of carriers (electrons and holes) without being blocked, thereby improving carrier mobility and increasing radiative recombination. At the same time, its thinness means that the influence of lattice mismatch with the substrate is relatively small.

[0036] Both the first and second space layers begin and end with an aluminum gallium indium phosphide (AGaInP) layer. This means that the superlattice structure has one more AGaInP layer than the aluminum phosphide (AP) layer. This ensures that the upper and lower surfaces of the first and second space layers are lattice-matched with the substrate, further reducing the adverse effects of lattice mismatch between the AP and the substrate. Attached Figure Description

[0037] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings of the embodiments will be briefly introduced below. Obviously, the drawings in the following description only involve some embodiments of this application and are not intended to limit this application.

[0038] Figure 1 A schematic diagram of the epitaxial structure of a red light-emitting diode according to the first embodiment of this disclosure is shown.

[0039] Figure 2 It shows Figure 1 A schematic diagram of the structure of the first spatial layer.

[0040] Figure 3 It shows Figure 1 A schematic diagram of the structure of the second spatial layer.

[0041] Figure 4 A schematic diagram of the epitaxial structure of a red light-emitting diode according to a second embodiment of the present disclosure is shown.

[0042] Figure 5 It shows Figure 4 A schematic diagram of the structure of the first spatial layer.

[0043] Figure 6 It shows Figure 4 A schematic diagram of the structure of the second spatial layer. Detailed Implementation

[0044] The following detailed description, in conjunction with the accompanying drawings and specific embodiments, provides a further detailed explanation of the epitaxial structure of the red light-emitting diode and its fabrication method proposed in this disclosure. The advantages and features of this disclosure will become clearer from the following description. It should be noted that the drawings are all in a very simplified form and use non-precise proportions, and are only used to facilitate and clarify the illustration of the embodiments of this disclosure.

[0045] Figure 1 A schematic diagram of the epitaxial structure of a red light-emitting diode according to an embodiment of the present disclosure is shown. Figure 2 It shows Figure 1 A schematic diagram of the structure of the first spatial layer. Figure 3 It shows Figure 1 A schematic diagram of the structure of the second spatial layer.

[0046] like Figures 1 to 3As shown, the epitaxial structure of the red light-emitting diode in this embodiment of the present disclosure is, for example, an anti-polarity red light-emitting diode epitaxial structure, which includes, from bottom to top, a substrate 101, a buffer layer 102, an etching stop layer 103, a first semiconductor layer 11, a first space layer 140, a multiple quantum well structure 150, a second space layer 160, and a second semiconductor layer 12. The doping types of the first semiconductor layer 11 and the second semiconductor layer 12 are opposite. In this embodiment, the doping type of the first semiconductor layer is N-type, and the doping type of the second semiconductor layer is P-type.

[0047] In this embodiment, the buffer layer 102 is adjacent to the substrate 101, which can reduce the defects and dislocations in the epitaxial structure caused by surface defects of the substrate 101, and provide a high-quality growth surface for the structural layer above the buffer layer 102.

[0048] In some preferred embodiments, the substrate 101 is a gallium arsenide substrate. The thickness of the buffer layer 102 ranges from 100 nm to 500 nm, and the material of the buffer layer 102 is, for example, gallium arsenide.

[0049] In this embodiment, the etching cutoff layer 103 is used to remove the substrate 101 and the buffer layer 102 in conjunction with the reverse polarity red light-emitting diode process, thereby preparing an N-side light-emitting reverse polarity red light-emitting diode, which has higher photoelectric efficiency than a P-side light-emitting positive polarity red light-emitting diode.

[0050] In some preferred embodiments, the thickness of the corrosion stop layer 103 ranges from 100 nm to 500 nm, and the material of the corrosion stop layer 103 is, for example, Ga. x In (1-x) P. In some specific embodiments, x = 0.5, but is not limited thereto.

[0051] In this embodiment, the first semiconductor layer 11 includes, from bottom to top, a first ohmic contact layer 110, a first current spreading layer 120, and a first confinement layer 130. The first ohmic contact layer 110 is located on the etch stop layer 103, and the first space layer 140 is located on the first confinement layer 130. The first ohmic contact layer 110 forms an ohmic contact with the N-electrode, thereby fabricating an N-side light-emitting diode with reverse polarity (RTD). The first current spreading layer 120 is used to enhance current spreading and improve the brightness of the RTD in conjunction with the roughening process of the RTD. The first confinement layer 130 provides electrons.

[0052] In some preferred embodiments, the thickness of the first ohmic contact layer 110 ranges from 50 nm to 200 nm, and the material of the first ohmic contact layer 110 is, for example, gallium arsenide, and the doping type of the first ohmic contact layer 110 is, for example, N-type. For example, the dopant in the first ohmic contact layer 110 may be Si, Te, etc., and the doping concentration may be greater than 1E19cm⁻¹. -3 .

[0053] In some preferred embodiments, the thickness of the first current spreading layer 120 ranges from 2 to 8 μm, and the material of the first current spreading layer 120 is, for example, (Al). k Ga 1-k ) 0.5 In 0.5 P, the doping type of the first current spreading layer 120 is, for example, N-type. For example, the doped impurities in the first current spreading layer 120 are Si, Te, etc., and the doping concentration ranges from 3E18 to 5E18 cm⁻¹. -3 .

[0054] In some preferred embodiments, the thickness of the first confinement layer 130 ranges from 300 nm to 500 nm, and the material of the first confinement layer 130 is, for example, Al. 0.5 In 0.5 P, the doping type of the first confinement layer 130 is, for example, N-type. For example, the doped impurities in the first confinement layer 130 are Si, Te, etc., and the doping concentration ranges from 2E18 to 4E18 cm⁻¹. -3 .

[0055] In this embodiment, the first space layer 140 is a superlattice structure, including alternating stacked aluminum gallium indium phosphide (AGaInP) layers 141 and aluminum phosphide (APP) layers 142. The structural layers on the two opposite outer surfaces of the first space layer 140 are both AGaInP layers 141, that is, AGaInP layers 141 have one more layer than AAPP layers 142. This makes the upper and lower surfaces of the first space layer 140 lattice-matched between AGaInP layers 141 and the substrate 101, thereby reducing the adverse effects caused by the lattice mismatch between AAPP layers 142 and the substrate 101.

[0056] In some specific embodiments, the first space layer 140 has 7 to 10 stacked pairs. The material of the gallium indium phosphide layer 141 is, for example, (Al). a Ga 1-a ) 0.5 In 0.5 The values ​​of P and a range from 0.5 to 0.8. The thickness of the monolayer aluminum gallium indium phosphide 141 ranges from 9 nm to 11 nm. The thickness of the monolayer aluminum phosphide 142 ranges from 0.5 nm to 1 nm. Preferably, the monolayer aluminum phosphide 142 comprises 1 to 3 aluminum phosphide monolayers, with a relatively thin thickness to facilitate carrier tunneling without obstruction, while also minimizing the impact of lattice mismatch with the substrate 101.

[0057] In some preferred embodiments, multiple pairs of stacked layers on the side of the first space layer 140 away from the multi-quantum-well structure 150 are doped with impurities, for example, N-type, to improve carrier mobility, and the number of doped stacked layers includes 2 to 3 pairs. In other embodiments, the first space layer 140 is an unintentionally doped layer.

[0058] In this embodiment, the multi-quantum well structure 150 adopts a multi-quantum well structure with N cycles of alternating well layers and barrier layers.

[0059] In some preferred embodiments, the number of periods N in the multi-quantum well structure 150 ranges from 3 to 30. The well layer is (Al) x Ga 1-x ) 0.5 In 0.5 The P-layer has a thickness x ranging from 0 to 0.3, and the well layer has a single-layer thickness ranging from 4 nm to 8 nm. The barrier layer is (Al). y Ga 1-y ) 0.5 In 0.5 The P layer has a y range of 0.3 to 0.6, and the single-layer thickness of the barrier layer ranges from 6 nm to 10 nm.

[0060] In this embodiment, the second space layer 160 is a superlattice structure, including alternating stacked aluminum gallium indium phosphide (AGaInP) layers 161 and aluminum phosphide (APP) layers 162. The structural layers on the two opposite outer surfaces of the second space layer 160 are both AGaInP layers 161, that is, AGaInP layers 161 have one more layer than AAPP layers 162. This makes the upper and lower surfaces of the second space layer 160 lattice-matched between AGaInP layers 161 and the substrate 101, thereby reducing the adverse effects caused by the lattice mismatch between AAPP layers 162 and the substrate 101.

[0061] In some specific embodiments, the second space layer 160 has 10 to 13 stacked pairs. The material of the gallium indium phosphide layer 161 is, for example, Al(II)2O3. b Ga 1-b ) 0.5 In 0.5 The values ​​of P and b range from 0.5 to 0.8. The thickness of the monolayer aluminum gallium indium phosphide (AGaInP) layer 161 ranges from 9 nm to 11 nm. The thickness of the monolayer aluminum phosphide (APH) layer 162 ranges from 0.5 nm to 1 nm. The monolayer aluminum phosphide (APH) layer 162 comprises 1 to 3 aluminum phosphide monolayers, and its thinness allows charge carriers to tunnel through without being blocked. Simultaneously, its thinness minimizes the impact of lattice mismatch with the substrate 101. Preferably, the thickness of the second space layer 160 is greater than or equal to the thickness of the first space layer 140.

[0062] In some preferred embodiments, multiple pairs of stacked layers in the second space layer 160 on the side away from the multi-quantum-well structure 150 are doped with impurities, for example, P-type, to improve carrier mobility, and the number of doped stacked layers includes 2 to 3 pairs. In other embodiments, the second space layer 160 is an unintentionally doped layer.

[0063] In this embodiment, the aluminum gallium indium phosphide (AGaInP) layers in the first space layer 140 and the second space layer 160 have a higher aluminum content than the AGaInP in the multi-quantum well structure 150. That is, the first space layer 140 and the second space layer 160 have a higher bandgap than the multi-quantum well structure 150, thereby further enhancing the carrier confinement effect, suppressing carrier overflow, and thus enhancing the carrier recombination probability, improving the photoelectric efficiency and reliability of the red light-emitting diode.

[0064] In this embodiment, the second semiconductor layer 12 includes, from bottom to top, a second confinement layer 170, a second current spreading layer 180, and a second ohmic contact layer 190, wherein the second confinement layer 170 is located on the second space layer 160. The second confinement layer 170 is used to provide holes. The second current spreading layer 180 serves as a window layer to increase current spreading and reduce the operating voltage of the red light-emitting diode. The second ohmic contact layer 190 is used to form an ohmic contact with the P electrode.

[0065] In this embodiment, the first confinement layer 130 and the second confinement layer 170 serve two main functions as confinement layers: on the one hand, they confine minority carriers from overflowing the multi-quantum-well structure 150, thereby improving recombination luminescence efficiency; on the other hand, they provide carriers to facilitate radiative recombination and improve the luminescence efficiency of the red light-emitting diode.

[0066] In some preferred embodiments, the thickness of the second confinement layer 170 ranges from 300 nm to 500 nm, and the material of the second confinement layer 170 is, for example, Al. 0.5 In 0.5 The second confinement layer 170 is, for example, doped with P-type. For instance, the dopant in the second confinement layer 170 may be Mg, Zn, etc., with a doping concentration ranging from 2E18 to 4E18 cm⁻¹. -3 .

[0067] In some preferred embodiments, the thickness of the second current spreading layer 180 ranges from 3 to 11 μm, and the material of the second current spreading layer 180 is, for example, GaP, and the doping type of the second current spreading layer 180 is, for example, p-type. For example, the dopant in the second current spreading layer 180 is Mg, Zn, etc., and the doping concentration ranges from 3E18 to 5E18 cm⁻¹. -3 .

[0068] In some preferred embodiments, the thickness of the second ohmic contact layer 190 ranges from 100 nm to 200 nm, and the material of the second ohmic contact layer 190 is, for example, GaP, and the doping type of the second ohmic contact layer 190 is, for example, p-type. For example, the dopant in the second ohmic contact layer 190 is Mg, Zn, etc., and the doping concentration is greater than 1E19 cm⁻¹. -3 .

[0069] Figure 4 A schematic diagram of the epitaxial structure of a red light-emitting diode according to the second embodiment of this disclosure is shown. Figure 5 It shows Figure 4 A schematic diagram of the structure of the first spatial layer. Figure 6 It shows Figure 4 A schematic diagram of the structure of the second spatial layer.

[0070] like Figures 4 to 6 As shown, the epitaxial structure of the red light-emitting diode in this embodiment is, for example, a positive polarity red light-emitting diode epitaxial structure, which includes, from bottom to top, a substrate 201, a buffer layer 202, a mirror layer 203, a first semiconductor layer 21, a first space layer 220, a multiple quantum well structure 230, a second space layer 240, and a second semiconductor layer 22. The doping types of the first semiconductor layer 21 and the second semiconductor layer 22 are opposite. In this embodiment, the doping type of the first semiconductor layer is N-type, and the doping type of the second semiconductor layer is P-type.

[0071] In this embodiment, the buffer layer 202 is adjacent to the substrate 201, which can reduce the defects and dislocations in the epitaxial structure caused by surface defects of the substrate 201, and provide a high-quality growth surface for the structural layer above the buffer layer 202.

[0072] In some preferred embodiments, the substrate 201 is a gallium arsenide substrate. The thickness of the buffer layer 202 ranges from 100 nm to 500 nm, and the material of the buffer layer 202 is, for example, gallium arsenide.

[0073] In this embodiment, the reflector layer 203 is a distributed Bragg reflector to reduce light absorption by the substrate 201.

[0074] In this embodiment, the first semiconductor layer 21 includes a first confinement layer 210 for providing electrons.

[0075] In some preferred embodiments, the thickness of the first confinement layer 210 ranges from 300 nm to 500 nm, and the material of the first confinement layer 210 is, for example, Al. 0.5 In 0.5 P, the doping type of the first confinement layer 220 is, for example, N-type. For example, the doped impurities in the first confinement layer 220 are Si, Te, etc., and the doping concentration ranges from 2E18 to 4E18 cm⁻¹.-3 .

[0076] In this embodiment, the first space layer 220 is a superlattice structure, including alternating stacked aluminum gallium indium phosphide (AGaInP) layers 221 and aluminum phosphide (APP) layers 222. The structural layers on the two opposite outer surfaces of the first space layer 220 are both AGaInP layers 221, that is, AGaInP layers 221 have one more layer than AAPP layers 222. This makes the upper and lower surfaces of the first space layer 220 lattice-matched between AGaInP layers 221 and substrate 201, thereby reducing the adverse effects caused by lattice mismatch between AAPP layers 222 and substrate 201.

[0077] In some specific embodiments, the first space layer 220 has 7 to 10 stacked pairs. The material of the gallium indium phosphide layer 221 is, for example, (Al). a Ga 1-a ) 0.5 In 0.5 The values ​​of P and a range from 0.5 to 0.8. The thickness of the monolayer aluminum gallium indium phosphide (AGaInP) layer 221 ranges from 9 nm to 11 nm. The thickness of the monolayer aluminum phosphide (APH) layer 222 ranges from 0.5 nm to 1 nm. Preferably, the monolayer aluminum phosphide (APH) layer 222 comprises 1 to 3 aluminum phosphide monolayers, with a relatively thin thickness to facilitate carrier tunneling without obstruction, while also minimizing the impact of lattice mismatch with the substrate 201.

[0078] In some preferred embodiments, multiple pairs of stacked layers on the side of the first space layer 220 away from the multi-quantum-well structure 230 are doped with impurities, for example, N-type, to improve carrier mobility, and the number of doped stacked layer pairs includes 2 to 3 pairs. In other embodiments, the first space layer 220 is an unintentionally doped layer.

[0079] In this embodiment, the multi-quantum well structure 230 adopts a multi-quantum well structure with N cycles of alternating well layers and barrier layers.

[0080] In some preferred embodiments, the number of periods N in the multi-quantum well structure 230 ranges from 3 to 30. The well layer is (Al) x Ga 1-x ) 0.5 In 0.5 The P-layer has a thickness x ranging from 0 to 0.3, and the well layer has a single-layer thickness ranging from 4 nm to 8 nm. The barrier layer is (Al). y Ga 1-y ) 0.5 In 0.5 The P layer has a y range of 0.3 to 0.6, and the single-layer thickness of the barrier layer ranges from 6 nm to 10 nm.

[0081] In this embodiment, the second space layer 240 is a superlattice structure, including alternating stacked aluminum gallium indium phosphide (AGaInP) layers 241 and aluminum phosphide (APP) layers 242. The structural layers on the two opposite outer surfaces of the second space layer 240 are both AGaInP layers 241, that is, AGaInP layers 241 have one more layer than AAPP layers 242. This makes the upper and lower surfaces of the second space layer 240 lattice-matched between AGaInP layers 241 and the substrate 201, so as to reduce the adverse effects caused by the lattice mismatch between AAPP layers 242 and the substrate 201.

[0082] In some specific embodiments, the second space layer 240 has 10 to 13 stacked pairs. The material of the gallium indium phosphide layer 241 is, for example, (Al). b Ga 1-b ) 0.5 In 0.5 The values ​​of P and b range from 0.5 to 0.8. The thickness of the monolayer aluminum gallium indium phosphide (AGaInP) layer 241 ranges from 9 nm to 11 nm. The thickness of the monolayer aluminum phosphide (APH) layer 242 ranges from 0.5 nm to 1 nm. The monolayer aluminum phosphide (APH) layer 242 comprises 1 to 3 aluminum phosphide monolayers, and its thinness allows charge carriers to tunnel through without being blocked. Simultaneously, its thinness minimizes the impact of lattice mismatch with the substrate 201. Preferably, the thickness of the second space layer 240 is greater than or equal to the thickness of the first space layer 220.

[0083] In some preferred embodiments, multiple pairs of stacked layers on the side of the second space layer 240 away from the multi-quantum-well structure 250 are doped with impurities, for example, P-type, to improve carrier mobility, and the number of doped stacked layers includes 2 to 3 pairs. In other embodiments, the second space layer 240 is an unintentionally doped layer.

[0084] In this embodiment, the aluminum gallium indium phosphide (AGaInP) layers in the first space layer 220 and the second space layer 240 have a higher aluminum content than the AGaInP in the multi-quantum well structure 230. That is, the first space layer 220 and the second space layer 240 have a higher bandgap than the multi-quantum well structure 230, thereby further enhancing the carrier confinement effect, suppressing carrier overflow, and thus enhancing the carrier recombination probability, improving the photoelectric efficiency and reliability of the red light-emitting diode.

[0085] In this embodiment, the second semiconductor layer 22 includes, from bottom to top, a second confinement layer 250, a second current spreading layer 260, and a second ohmic contact layer 270, wherein the second confinement layer 250 is located on the second space layer 240. The second confinement layer 250 provides holes. The second current spreading layer 260 serves as a window layer to increase current spreading and reduce the operating voltage of the red light-emitting diode. The second ohmic contact layer 270 forms an ohmic contact with the P-electrode.

[0086] In this embodiment, the first confinement layer 210 and the second confinement layer 250 serve two main functions as confinement layers: on the one hand, they confine minority carriers from overflowing the multi-quantum-well structure 230, thereby improving recombination luminescence efficiency; on the other hand, they provide carriers to facilitate radiative recombination and improve the luminescence efficiency of the red light-emitting diode.

[0087] In some preferred embodiments, the thickness of the second confinement layer 250 ranges from 300 nm to 500 nm, and the material of the second confinement layer 250 is, for example, Al. 0.5 In 0.5 The second confinement layer 250 is, for example, p-type doped. For instance, the dopant in the second confinement layer 250 may be Mg, Zn, etc., with a doping concentration ranging from 2E18 to 4E18 cm⁻¹. -3 .

[0088] In some preferred embodiments, the thickness of the second current spreading layer 260 ranges from 3 to 11 μm, and the material of the second current spreading layer 260 is, for example, GaP, and the doping type of the second current spreading layer 260 is, for example, p-type. For example, the dopant in the second current spreading layer 260 is Mg, Zn, etc., and the doping concentration ranges from 3E18 to 5E18 cm⁻¹. -3 .

[0089] In some preferred embodiments, the thickness of the second ohmic contact layer 270 ranges from 100 nm to 200 nm, and the material of the second ohmic contact layer 270 is, for example, GaP, and the doping type of the second ohmic contact layer 270 is, for example, p-type. For example, the dopant in the second ohmic contact layer 270 is Mg, Zn, etc., and the doping concentration is greater than 1E19 cm⁻¹. -3 .

[0090] This disclosure also provides a method for fabricating a red light-emitting diode epitaxial structure, comprising: sequentially forming a buffer layer 102, an etching stop layer 103, a first semiconductor layer 11, a first space layer 140, a multiple quantum well structure 150, a second space layer 160, and a second semiconductor layer 12 on a substrate 101, wherein the doping types of the first semiconductor layer 11 and the second semiconductor layer 12 are opposite. In this embodiment, the first semiconductor layer is N-type doped, and the second semiconductor layer is P-type doped. For a detailed structure, please refer to [reference needed]. Figures 1 to 3 The relevant descriptions will not be repeated here.

[0091] This disclosure also provides another method for fabricating a red light-emitting diode epitaxial structure, comprising: sequentially forming a buffer layer 202, a mirror layer 203, a first semiconductor layer 21, a first space layer 220, a multiple quantum well structure 230, a second space layer 240, and a second semiconductor layer 22 on a substrate 202, wherein the doping types of the first semiconductor layer 21 and the second semiconductor layer 22 are opposite. In this embodiment, the first semiconductor layer is N-type doped, and the second semiconductor layer is P-type doped. See the specific structure for details. Figures 4 to 6 The relevant descriptions will not be repeated here.

[0092] The fabrication process of the red light-emitting diode epitaxial structure disclosed herein includes any one of MOCVD, molecular beam epitaxy, HVPE, plasma-assisted chemical vapor deposition, and sputtering, with MOCVD being preferred.

[0093] According to the epitaxial structure and fabrication method of the red light-emitting diode provided in the embodiments of this disclosure, by setting a first space layer and a second space layer of superlattice structure on both sides (n side and p side) of the multi-quantum well structure, the confinement effect of the multi-quantum well structure on charge carriers (electrons and holes) is enhanced, preventing the overflow of charge carriers, especially electrons. At the same time, it can effectively prevent the diffusion of doping sources into the multi-quantum well structure, reduce the non-radiative recombination centers caused by doping sources in the multi-quantum well structure, enhance the crystal quality of the multi-quantum well structure, and improve the radiative recombination efficiency. Meanwhile, charge carriers can also enter the multi-quantum well structure through the tunneling effect to undergo radiative recombination, thereby improving the photoelectric performance and reliability of the red light-emitting diode.

[0094] Furthermore, the superlattice structures of both the first and second space layers are composed of alternating stacks of aluminum phosphide and aluminum gallium indium phosphide layers. Since the stacks are composed of two different materials, the crystal interface of the superlattice structure is clearer, resulting in better crystal quality.

[0095] In the first space layer, the second space layer, and the multi-quantum well structure, the aluminum gallium indium phosphide (AGaInP) layer in the first and second space layers has a higher aluminum content than the AGaInP layer in the well layer and barrier layer of the multi-quantum well structure. This means that the first and second space layers have a higher bandgap than the multi-quantum well structure, which further enhances the carrier confinement effect, suppresses carrier overflow, and thus enhances the carrier recombination probability, thereby improving the photoelectric efficiency and reliability of the red light-emitting diode.

[0096] Furthermore, since charge carriers diffuse toward the multi-quantum-well structure due to concentration differences, and the diffusion lengths of P-type doping and N-type doping are different, in order to prevent charge carriers from entering the multi-quantum-well structure due to diffusion, the stacking log number of the second spatial layer is set to be greater than or equal to the stacking log number of the first spatial layer, so that the thickness of the second spatial layer is greater than or equal to the thickness of the first spatial layer, thereby maximizing the recombination of electrons and holes in the multi-quantum-well structure to emit light, thus effectively controlling the light field distribution.

[0097] Furthermore, since both the first and second space layers are superlattice structures, the aluminum phosphorus layer, in addition to suppressing carrier overflow, can also prevent doping sources from entering the multi-quantum well structure. The aluminum phosphorus layer is very thin, with only 1 to 3 monolayers, which facilitates the tunneling of carriers (electrons and holes) without being blocked, thereby improving carrier mobility and increasing radiative recombination. At the same time, its thinness means that the influence of lattice mismatch with the substrate is relatively small.

[0098] Both the first and second space layers begin and end with an aluminum gallium indium phosphide (AGaInP) layer. This means that the superlattice structure has one more AGaInP layer than the aluminum phosphide (AP) layer. This ensures that the upper and lower surfaces of the first and second space layers are lattice-matched with the substrate, further reducing the adverse effects of lattice mismatch between the AP and the substrate.

[0099] Furthermore, it is understood that although this disclosure has been presented above with preferred embodiments, these embodiments are not intended to limit this disclosure. For any person skilled in the art, many possible variations and modifications can be made to the technical solutions of this disclosure using the disclosed technical content, or equivalent embodiments with equivalent changes, without departing from the scope of the technical solutions of this disclosure. Therefore, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of this disclosure, without departing from the content of the technical solutions of this disclosure, shall still fall within the scope of protection of the technical solutions of this disclosure.

Claims

1. An epitaxial structure for a red light-emitting diode, comprising: The substrate, the first semiconductor layer, the multi-quantum well structure, and the second semiconductor layer are stacked sequentially from bottom to top, with the first semiconductor layer and the second semiconductor layer having opposite doping types; A first spatial layer is located between the first semiconductor layer and the multi-quantum-well structure; as well as The second spatial layer is located between the second semiconductor layer and the multi-quantum-well structure. The first and second space layers are superlattice structures, and both the first and second space layers include alternating stacked aluminum phosphide and aluminum gallium indium phosphide layers. The substrate includes a gallium arsenide substrate, and the structural layers on the two opposite outer surfaces of the first spatial layer are aluminum gallium indium phosphide layers, and the structural layers on the two opposite outer surfaces of the second spatial layer are aluminum gallium indium phosphide layers.

2. The epitaxial structure of a red light-emitting diode according to claim 1, wherein, The first semiconductor layer is an N-type semiconductor layer, and the second semiconductor layer is a P-type semiconductor layer.

3. The red light-emitting diode epitaxial structure according to claim 2, wherein, The number of stacked pairs in the second spatial layer is greater than or equal to the number of stacked pairs in the first spatial layer.

4. The red light-emitting diode epitaxial structure according to claim 2, wherein, The second spatial layer has 10 to 13 stacked pairs, and the first spatial layer has 7 to 10 stacked pairs.

5. The epitaxial structure of a red light-emitting diode according to claim 1, wherein, A portion of the stack in the first spatial layer on the side furthest from the multi-quantum-well structure has doped impurities, and / or, A portion of the stack in the second spatial layer on the side away from the multi-quantum well structure has doped impurities.

6. The red light-emitting diode epitaxial structure according to claim 5, wherein, The number of stacked pairs with doped impurities in the first spatial layer includes 2 to 3 pairs. The number of stacked pairs with doped impurities in the second spatial layer includes 2 to 3 pairs.

7. The epitaxial structure of a red light-emitting diode according to claim 1, wherein, In the first space layer and the second space layer, the thickness of a single aluminum phosphide layer ranges from 0.5 to 1 nm, and the thickness of a single aluminum gallium indium phosphide layer ranges from 9 to 11 nm.

8. The red light-emitting diode epitaxial structure according to claim 7, wherein, The single-layer aluminum-phosphorus layer comprises 1 to 3 aluminum-phosphorus monolayers.

9. The epitaxial structure of a red light-emitting diode according to claim 1, wherein, The material of the multi-quantum well structure includes aluminum gallium indium phosphide, and the aluminum composition of the well layer and the barrier layer in the multi-quantum well structure is less than the aluminum composition of the aluminum gallium indium phosphide layer in the first space layer and the second space layer.

10. The epitaxial structure of a red light-emitting diode according to any one of claims 1-9, wherein, The first semiconductor layer includes a first confinement layer, which is adjacent to the first space layer. Between the first confinement layer and the substrate, there is also a buffer layer and a mirror layer disposed sequentially from bottom to top.

11. The epitaxial structure of a red light-emitting diode according to any one of claims 1-9, wherein, The first semiconductor layer includes a first ohmic contact layer, a first current spreading layer and a first confinement layer arranged sequentially from bottom to top. Between the first ohmic contact layer and the substrate, there is also a buffer layer and an etching stop layer arranged sequentially from bottom to top.

12. The epitaxial structure of a red light-emitting diode according to any one of claims 1-9, wherein, The second semiconductor layer includes a second confinement layer, a second current spreading layer, and a second ohmic contact layer disposed sequentially from bottom to top.

13. A method for manufacturing a red light-emitting diode epitaxial structure, comprising sequentially forming, from bottom to top, a first semiconductor layer, a first space layer, a multiple quantum well structure, a second space layer, and a second semiconductor layer on a substrate, wherein the first semiconductor layer and the second semiconductor layer have opposite doping types. in, The first and second space layers are superlattice structures, and both the first and second space layers include alternating stacked aluminum phosphide and aluminum gallium indium phosphide layers. The substrate includes a gallium arsenide substrate, and the structural layers on the two opposite outer surfaces of the first spatial layer are aluminum gallium indium phosphide layers, and the structural layers on the two opposite outer surfaces of the second spatial layer are aluminum gallium indium phosphide layers.

14. The manufacturing method according to claim 13, wherein, The first semiconductor layer is an N-type semiconductor layer, and the second semiconductor layer is a P-type semiconductor layer.

15. The manufacturing method according to claim 14, wherein, The number of stacked pairs in the second spatial layer is greater than or equal to the number of stacked pairs in the first spatial layer.

16. The manufacturing method according to claim 14, wherein, The second spatial layer has 10 to 13 stacked pairs, and the first spatial layer has 7 to 10 stacked pairs.

17. The manufacturing method according to claim 13, wherein, A portion of the stack in the first spatial layer on the side furthest from the multi-quantum-well structure has doped impurities, and / or, A portion of the stack in the second spatial layer on the side away from the multi-quantum well structure has doped impurities.

18. The manufacturing method according to claim 17, wherein, The number of stacked pairs with doped impurities in the first spatial layer includes 2 to 3 pairs. The number of stacked pairs with doped impurities in the second spatial layer includes 2 to 3 pairs.

19. The manufacturing method according to claim 13, wherein, In the first space layer and the second space layer, the thickness of a single aluminum phosphide layer ranges from 0.5 to 1 nm, and the thickness of a single aluminum gallium indium phosphide layer ranges from 9 to 11 nm.

20. The manufacturing method according to claim 19, wherein, The single-layer aluminum-phosphorus layer comprises 1 to 3 aluminum-phosphorus monolayers.

21. The manufacturing method according to claim 13, wherein, The material of the multi-quantum well structure includes aluminum gallium indium phosphide, and the aluminum composition of the well layer and the barrier layer in the multi-quantum well structure is less than the aluminum composition of the aluminum gallium indium phosphide layer in the first space layer and the second space layer.

22. The manufacturing method according to any one of claims 13-21, wherein, The first semiconductor layer includes a first confinement layer, which is adjacent to the first space layer. The manufacturing method further includes forming a buffer layer and a mirror layer sequentially from bottom to top between the first confinement layer and the substrate.

23. The manufacturing method according to any one of claims 13-21, wherein, The first semiconductor layer includes a first ohmic contact layer, a first current spreading layer and a first confinement layer disposed sequentially from bottom to top. The manufacturing method further includes forming a buffer layer and an etching stop layer sequentially from bottom to top between the first ohmic contact layer and the substrate.

24. The manufacturing method according to any one of claims 13-21, wherein, Forming the second semiconductor layer includes forming a second confinement layer, a second current spreading layer, and a second ohmic contact layer sequentially from bottom to top on the second space layer.

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