Epitaxial structure, manufacturing method and chip structure

Abstract

The invention provides an epitaxial structure, a manufacturing method and a chip structure. The epitaxial structure comprises a plurality of sub-active layers, wherein each sub active layer is doped with doping elements with different concentrations. As and / or Sb trace elements are doped into the active layer, so that the disorder degree of the active layer is improved, and the internal quantum efficiency and the luminous efficiency are improved. By adopting a segmented doping mode, the forbidden bandwidth difference caused by strain accumulation of quantum well layer materials at different positions is corrected, so that the light-emitting wavelength is more consistent, and the light-emitting efficiency is further improved.

Description

Technical Field

[0001] The present application relates to the field of microdisplay, and further to an epitaxial structure and a manufacturing method, and a chip structure. The epitaxial structure is particularly suitable for microdisplay. Background Art

[0002] Inorganic micro-pixel light-emitting diodes, also known as micro-light-emitting diodes, Micro LEDs, or μ-LEDs, have become increasingly important since they have been used in various applications, including self-luminous micro-displays, visible light communications, optogenetics, etc. Compared with traditional LEDs, Micro LEDs have the advantages of small size, high resolution per unit area, faster response speed, wider operating temperature range, higher resolution, wider color gamut, higher reliability, lower power consumption, and higher current density.

[0003] In the epitaxial structure used for micro-display light-emitting diodes, the quantum well layer material composition, growth rate, growth temperature, etc. have a significant impact on product performance, especially the internal quantum efficiency. In particular, the increase in the disorder of the quantum well layer can effectively improve the LED luminous efficiency. Since the quantum well layer is very thin, the use of low-speed growth causes the atoms to be arranged in order and then incorporated into the lattice, thereby increasing the CuPt-like ordered structure of the material of the quantum well layer. The increase in ordered structure is more unfavorable for improving the LED luminous efficiency. If the growth rate is too fast, although the disorder increases, in a very short time, the stability of the reaction chamber flow field environment is poor, the growth quality of the epitaxial material is poor, and it has a counter-effect on the improvement of light efficiency. Therefore, it is particularly important to increase the disorder of the quantum well layer when the growth rate is limited. Summary of the invention

[0004] In order to solve the above technical problems, the present application provides an epitaxial structure and a manufacturing method, and a micro LED chip structure including the epitaxial structure, which improves the disorder of the active layer by doping trace elements in the active layer, thereby improving the internal quantum efficiency (IQE). In addition, the trace elements doped into the quantum well layer are doped in sections to correct the difference in bandgap width caused by strain accumulation in the quantum well layer materials at different positions, so that the emission wavelength is more consistent.

[0005] In order to achieve at least one of the above purposes, an epitaxial structure includes:

[0006] Multiple sub-active layers; wherein each sub-active layer is doped with doping elements of different concentrations.

[0007] In some embodiments, the doping concentration in the multiple sub-active layers increases from top to bottom.

[0008] In some embodiments, the doping concentration of the doping element is 1e18-5e16.

[0009] In some embodiments, the active layer includes five sub-active layers, namely, from bottom to top, a first sub-active layer, a second sub-active layer, a third sub-active layer, a fourth sub-active layer and a fifth sub-active layer, wherein the concentration range of As and / or Sb elements doped in the quantum wells in the first sub-active layer is 1e18 to 2e18, the concentration range of As and / or Sb elements doped in the quantum wells in the second sub-active layer is 5e17 to 1e18, the concentration range of As and / or Sb elements doped in the quantum wells in the third sub-active layer is 1e17 to 5e17, the concentration range of As and / or Sb elements doped in the quantum wells in the fourth sub-active layer is 5e16 to 1e17, and the concentration range of As and / or Sb elements doped in the quantum wells in the fifth sub-active layer is 1e16 to 5e16.

[0010] In some embodiments, the doping element is As and / or Sb.

[0011] In some embodiments, each sub-active layer includes a quantum barrier layer and a quantum well layer; and the doping element is doped in the quantum well layer.

[0012] In some embodiments, the thickness of the quantum barrier layer is greater than the thickness of the quantum well layer.

[0013] In some embodiments, the material of the quantum barrier layer is (Al x Ga 1-x ) y In 1-y P, wherein the range of x is 0.6-1, the range of y is 0.4-0.6, and the thickness of the quantum barrier layer is in the range of 10nm-40nm.

[0014] In some embodiments, the material of the quantum well layer is (Al x Ga 1-x ) y In 1-y P, wherein the range of x is 0-0.15, the range of y is 0.4-0.6, and the thickness of the quantum well layer is 2nm-10nm.

[0015] In some embodiments, the epitaxial structure includes a substrate, a first semiconductor epitaxial layer, an active layer, and a second semiconductor epitaxial layer arranged in sequence from bottom to top; the first semiconductor epitaxial layer and the second semiconductor epitaxial layer have different conductivity types.

[0016] In some embodiments, the substrate is a first conductivity type GaAs substrate or a substrate having the same crystal type as GaAs; or, the substrate is Ge or a substrate having the same crystal type as Ge.

[0017] In some embodiments, the crystal orientation is (100) <111> A is a first conductive type GaAs substrate of 2 to 15 degrees; or, Ge or a substrate having the same crystal type as Ge has a crystal orientation of (100) <111> 2°, 6° or 9°.

[0018] In some embodiments, the substrate also has a nucleation layer.

[0019] In some embodiments, the first semiconductor epitaxial layer includes, from top to bottom, a first waveguide layer, a first confinement layer, and a first ohmic contact layer.

[0020] In some embodiments, the bottom of the ohmic contact layer further includes a corrosion stop layer and a buffer layer.

[0021] In some embodiments, the nucleation layer is a material that is lattice matched to the buffer layer.

[0022] In some embodiments, the material of the nucleation layer is GaInP or AlGaInP.

[0023] In some embodiments, the material of the first buffer layer is GaAs, the material of the first corrosion stop layer is AlGaInP, the material of the first ohmic contact layer is GaAs, the material of the first confinement layer is AlInP, and the material of the first waveguide layer is AlGaInP or AlInP.

[0024] In some embodiments, the second semiconductor epitaxial layer includes, from bottom to top, a second waveguide layer, a second confinement layer, a second transition layer, a second window layer, and a second ohmic contact layer.

[0025] In some embodiments, the material of the second waveguide layer is AlGaInP or AlInP, the material of the second confinement layer is AlInP, the material of the second transition layer is AlGaInP, the material of the second window layer is GaP, and the material of the second ohmic contact layer is GaP.

[0026] In order to achieve the above objectives, the present invention also provides a micro LED chip structure, which includes the above-mentioned epitaxial structure; and a first electrode structure electrically connected to the first semiconductor epitaxial layer of the epitaxial structure, and a second electrode structure electrically connected to the second semiconductor epitaxial layer.

[0027] In order to achieve the above object, the present invention further provides a method for manufacturing the above epitaxial structure, characterized in that it comprises:

[0028] Step 01: Provide a substrate;

[0029] Step 02: growing a first semiconductor epitaxial layer on a substrate;

[0030] Step 03: growing an active layer on the first semiconductor epitaxial layer, and doping doping elements during the process of growing the active layer;

[0031] Step 04: Growing a second semiconductor epitaxial layer on the active layer.

[0032] In some embodiments, before step 02, the method further includes: step 011, heating the substrate to a preset temperature.

[0033] In some embodiments, the substrate is heated by pre-baking, the baking temperature is 650° C. to 800° C., and the baking time is 5 to 30 minutes.

[0034] In some embodiments, in step S03, the growth process of the doping elements in the active layer includes: using group III elements, group V elements and a doping source containing the doping elements, and adjusting the concentration of the doping elements by changing the flow rate of the doping source containing the doping elements.

[0035] Preferably, trimethyl gallium (TMGa) and trimethyl indium (TMIn) are used as the group III source, and phosphine (PH) and arsine (AsH 3 ), the ratio of group V source to group III source is 50-150, and antimony (Sb) element is introduced as a doping source through an antimony-containing MO source such as triethyl antimony (TESb); by adjusting AsH 3 and / or TESb flow rate, and adjust the doping concentration of As and / or Sb. In some embodiments, the growth conditions of the doping elements in the quantum well layer are: the growth temperature is maintained at 625° C. to 725° C., the growth rate is 0.3 μm / h to 0.5 μm / h, and the growth pressure is 50 mbar.

[0036] Technical effects of this application:

[0037] 1) In the epitaxial structure provided in the present application, trace elements are doped into the active layer to increase the disorder of the active layer and improve the internal quantum efficiency.

[0038] 2) In the epitaxial structure provided in the present application, the trace elements doped into the quantum well layer are doped in a segmented manner to correct the difference in bandgap width caused by strain accumulation in the quantum well layer materials at different positions, thereby making the emission wavelength more consistent.

[0039] 3) The doping in this application significantly reduces the order of the crystal structure of the active layer, causes a blue shift in the PL spectrum and increases the bandgap width of the active layer, but the doping does not introduce a new component phase. By adjusting the doping concentration of the doping element, the order and band width of the active layer can be effectively controlled, broadening its application in optoelectronic devices such as MicroLED displays and solar cells. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] The above and other objects, features and advantages of the present disclosure will become more apparent through a more detailed description of exemplary embodiments of the present disclosure in conjunction with the accompanying drawings, wherein like reference numerals generally represent like components in the exemplary embodiments of the present disclosure.

[0041] Figure 1 It is a structural schematic diagram of the epitaxial structure provided in this application;

[0042] Figure 2 It is a schematic diagram of the structure of the PL spectrum test results;

[0043] Figure 3 A flow chart of a method for manufacturing an epitaxial structure of the present application. DETAILED DESCRIPTION

[0044] The preferred embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although the preferred embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments described herein. On the contrary, these embodiments are provided to make the present disclosure more thorough and complete, and to fully convey the scope of the present disclosure to those skilled in the art.

[0045] refer to Figure 1 Some embodiments of the present application provide an epitaxial structure, including a substrate 10, a first semiconductor epitaxial layer 20, an active layer 30, and a second semiconductor epitaxial layer 40 arranged in sequence from bottom to top. The active layer 30 may adopt a superlattice multi-quantum well structure. In some embodiments, the active layer 30 is doped with As and / or Sb elements. By doping As and / or Sb trace elements into the active layer 30, the disorder of the active layer 30 is increased, and the internal quantum efficiency is improved.

[0046] In some embodiments, the active layer 30 may include a multi-layer stacked sub-active layer 31, each sub-active layer 31 includes a quantum barrier layer 311 and a quantum well layer 312, and As and / or Sb elements are doped in the quantum well layer 312. The disorder of the quantum well layer 312 is improved by doping As and / or Sb trace elements in the quantum well layer 312, thereby improving the internal quantum efficiency. Preferably, the thickness of the quantum barrier layer 311 is greater than the thickness of the quantum well layer 312, thereby improving the luminous efficiency of the quantum well layer.

[0047] Specifically, the material of the quantum barrier layer 311 is (Al x Ga 1-x ) y In 1-y P, wherein the range of x is 0.6 to 1, and the range of y is 0.4 to 0.6. The thickness of the quantum barrier layer 311 is in the range of 10 nm to 40 nm.

[0048] The material of the quantum well layer 312 is (Al x Ga 1-x ) y In 1-y P, where x ranges from 0 to 0.15, and y ranges from 0.4 to 0.6. The thickness of the quantum well layer 312 ranges from 2 nm to 10 nm. The doping concentration of As and / or Sb elements is 1e18 to 5e16. In some embodiments, the growth conditions of the quantum well layer 312 doped with As and / or Sb elements are: the growth temperature is maintained at 625°C to 725°C, the growth rate is 0.3 μm / H to 0.5 μm / H, and the growth pressure is 50 mbar. In addition, the V / III ratio is controlled within a reasonable range to promote the formation of high-quality crystals.

[0049] In some embodiments, the concentration of As and / or Sb elements doped in the quantum well layer 312 from bottom to top is in the form of segmented doping, which can correct the difference in the bandgap width of the quantum well layer 312 at different positions. The difference is caused by the strain accumulation of the quantum well 312, making the light-emitting wavelength more consistent. Preferably, in the epitaxial structure, since the strain accumulation of the quantum well layer 312 from bottom to top gradually increases, the light-emitting wavelength of the quantum well layer 312 from bottom to top becomes shorter. Therefore, the concentration of As and / or Sb elements doped in the quantum well layer 312 from top to bottom increases, thereby correcting the increase in the bandgap width of the quantum well layer from top to bottom, and the corresponding light-emitting wavelength becomes shorter, so that the light-emitting wavelength of the quantum well layer tends to be consistent, thereby improving the light-emitting efficiency.

[0050] In some embodiments, the active layer 30 includes multiple sub-active layers 31, such as five layers, which are, from bottom to top, a first sub-active layer 31a, a second sub-active layer 31b, a third sub-active layer 31c, a fourth sub-active layer 31d and a fifth sub-active layer 31e. Preferably, the concentration range of As and / or Sb elements doped in the quantum wells in the first sub-active layer 31a is 1e18~2e18, the concentration range of As and / or Sb elements doped in the quantum wells in the second sub-active layer 31b is 5e17~1e18, the concentration range of As and / or Sb elements doped in the quantum wells in the third sub-active layer 31c is 1e17~5e17, the concentration range of As and / or Sb elements doped in the quantum wells in the fourth sub-active layer 31d is 5e16~1e17, and the concentration range of As and / or Sb elements doped in the quantum wells in the fifth sub-active layer 31e is 1e16~5e16.

[0051] In some embodiments, the substrate 10 is a first conductive type GaAs substrate or a substrate having the same crystal type as GaAs. Preferably, the crystal orientation is (100) <111> A is a first conductive type GaAs substrate with an angle of 2 to 15 degrees. The GaAs layer can be of the first conductive type and can be either N-type or P-type. In other embodiments, the substrate 10 can be Ge or a substrate having the same crystal type as Ge. Preferably, the crystal orientation of Ge or the substrate having the same crystal type as Ge is (100) biased. <111> 2°, 6° or 9°. Here, the selected substrate must have good lattice matching with the subsequent buffer layer, etc., and can effectively reduce defects caused by lattice mismatch, thereby improving the crystal quality of the subsequently grown epitaxial layer.

[0052] In some embodiments, the first semiconductor epitaxial layer may include, from top to bottom, a first ohmic contact layer 21, a first confinement layer 22, and a first waveguide layer 23, from bottom to top; for example, the material of the first ohmic contact layer 21 may be GaAs, the first confinement layer 22 may be AlInP, the doping element may be Si, and the material of the first waveguide layer 23 may be AlGaInP or AlInP. The first semiconductor layer may have a first conductivity type, which may be N-type or P-type. In other embodiments, an etching stop layer 53 and a buffer layer 52 are further included at the bottom of the first ohmic contact layer 21. The material of the buffer layer 52 may be GaAs, with a thickness ranging from 150 to 250 nm, preferably 200 nm; the material of the etching stop layer 53 may be AlGaInP. Further, a nucleation layer 51 is formed on the substrate 10, and the buffer layer 52 is formed on the nucleation layer 51. The nucleation layer 51 may be a material that matches the lattice of the buffer layer 52, for example, GaInP or AlGaInP. The thickness of the nucleation layer 51 may range from 5 to 15 nm, preferably 10 nm.

[0053] It should be noted that the first semiconductor epitaxial layer 20 is an N-type semiconductor layer, and the second semiconductor epitaxial layer 40 is a P-type semiconductor layer. In some embodiments, the first semiconductor epitaxial layer 20 is a P-type semiconductor layer, and the first semiconductor epitaxial layer 40 is an N-type semiconductor layer. The specific types of the first semiconductor epitaxial layer 20 and the second semiconductor epitaxial layer 40 should not constitute a limitation to the present application.

[0054] In some embodiments, the corrosion stop layer 53 is further

[0055] In some embodiments, the second semiconductor epitaxial layer 40 includes a second waveguide layer 41, a second confinement layer 42, a second transition layer 43, and a second window layer 44 from bottom to top. The material of the second waveguide layer 41 is AlGaInP or AlInP, the material of the second confinement layer 42 is AlInP, and the doping element is Mg. The material of the second transition layer 43 is AlGaInP, and the material of the second window layer 44 is GaP. In addition, in some embodiments, a second ohmic contact layer 45 is formed on the top of the second semiconductor epitaxial layer 40, and the material of the second ohmic contact layer 45 can be GaP. Here, the conductivity type of the second semiconductor epitaxial layer is the second conductivity type. The second conductivity type is different from the first conductivity type. When the first conductivity type is N-type, the second conductivity type is P-type; or when the first conductivity type is P-type, the second conductivity type is N-type.

[0056] In the present application, as the As and / or Sb doping concentration increases, the order of the active layer gradually decreases, specifically the order of Ga and In atoms gradually decreases. This is because the As and / or Sb atoms have a larger radius and different chemical bonding characteristics, which makes it more difficult for them to find suitable sites in the lattice, thus easily causing local lattice distortion and strain, thereby reducing the overall order. In addition, as the As and / or Sb doping concentration increases, the bandgap width (Eg) of the active layer increases. Figure 2As shown, a laser with a wavelength of 532nm is used as the excitation light source and the measurement is carried out at room temperature. The active layer without As and / or Sb is compared with the active layer doped with As and / or Sb. As the As and / or Sb doping concentration increases, the luminescence wavelength of the active layer shows a significant blue shift. This shows that As and / or Sb doping causes the Eg of the material to be broadened, which is due to the decrease in order and increase in alloying degree caused by As and / or Sb doping, which causes the change of the energy band structure. In the case of no As and / or Sb doping, the PL spectrum of the GaInP epitaxial layer shows a sharper luminescence peak, WLP is 683nm, which is consistent with the characteristics of high-order materials. As the As and / or Sb doping amount increases, the PL spectrum peak gradually moves toward the short wavelength direction, and the spectrum intensity decreases rapidly. When the As and / or Sb doping effective amount is 4.6, the WLP is 665nm. When the As and / or Sb doping effective amount is 13.8, the WLP is 652nm. And the spectrum width is significantly increased. This blue shift effect can be attributed to two reasons: first, As and / or Sb doping reduces the order of GaInP, causing the atomic arrangement to be more disordered, thereby increasing the bandgap of the material; second, the introduction of As and / or Sb atoms may form localized energy levels, resulting in a blue shift of the luminescence peak. At the same time, with the increase of As and / or Sb doping, the spectral intensity decreases rapidly, which is mainly due to the increase in heat loss caused by the increase in the metal-like band edge. In addition, the broadening of the PL spectrum also shows that the energy state distribution of the material has become more discrete, which may be due to the enhanced alloy disorder effect caused by As and / or Sb, and the enhanced alloy scattering, resulting in a wider energy level distribution in the luminescent area. Compared with the effects of other doping elements (such as nitrogen and oxygen) on GaInP materials, As and / or Sb have unique chemical properties, and their effects on the order and optical properties of the material are more significant. From the results of the PL spectrum blue shift, we can infer that in the case of undoped As and / or Sb, the Eg of the GaInP epitaxial layer is 1.814eV, and when the effective amount of As and / or Sb doping is 13.8, the Eg is 1.903eV, which is 89meV higher than that of undoped GaInP. The increase in Eg means the possibility of application in short-wavelength light-emitting devices and high-frequency electronic devices. Furthermore, by precisely controlling the doping concentration of As and / or Sb, the Eg of GaInP can be adjusted within a certain range to meet the needs of different application scenarios. Furthermore, As and / or Sb doping not only affects the order of the GaInP material, but also causes slight changes in the lattice constant, thereby affecting the stress state of the material. This stress change further regulates the band structure of the material, ultimately leading to changes in Eg.

[0057] In the manufacturing method of the epitaxial structure provided in the present application, a first semiconductor epitaxial layer, an active layer, and a second semiconductor epitaxial layer are grown on a substrate 10 using MOCVD growth technology, and As and / or Sb elements are doped during the growth of the active layer to form an active layer with a disordered crystal structure, thereby improving the luminous efficiency of the epitaxial structure; as the doping concentration in the quantum well layer increases, the bandgap width of the quantum well layer increases. Based on this, at some point, the luminous wavelength of each quantum well layer is not consistent due to the accumulation of strain in the active layer, and segmented doping can be used to correct the difference in the bandgap width of the quantum well layer, so that the luminous wavelength is more consistent, thereby further improving the luminous efficiency.

[0058] refer to Figure 3 According to another aspect of the present application, the present application further provides a method for manufacturing an epitaxial structure, comprising:

[0059] S01, providing a substrate 10;

[0060] S02, growing a first semiconductor layer 20 on the substrate 10;

[0061] S03, growing an active layer 30 on the first semiconductor layer 20, and doping elements during the process of growing the active layer 30;

[0062] S04 . Growing a second semiconductor layer 40 on the active layer 30 .

[0063] Before growing the first semiconductor layer 20 on the substrate 10 , the method further includes: S011 , heating the substrate 10 to a preset temperature.

[0064] In some embodiments, in the above step 01, the substrate 10 may be a first conductive type GaAs substrate or a substrate having a first conductive type and a first conductive type with GaAs. Preferably, the crystal orientation is (100). <111> A is a first conductive type GaAs substrate with an angle of 2 to 15 degrees. The GaAs layer can be of the first conductive type and can be either N-type or P-type. Alternatively, the substrate 10 can be Ge or a substrate having the same crystal type as Ge. Preferably, the crystal orientation of Ge or the substrate having the same crystal type as Ge is (100) <111> 2°, 6° or 9°.

[0065] In some embodiments, in the above step S01, the substrate 10 may be heated in a pre-baking manner, and the baking conditions may be: a baking temperature of 650° C. to 800° C. and a baking time of 5 to 30 minutes.

[0066] In some embodiments, before step S02, the method further includes: S011, growing a nucleation layer 51 on the substrate 10. The nucleation layer 51 may be a material that matches the lattice of the buffer layer 52, such as GaInP or AlGaInP. The thickness of the nucleation layer 51 may range from 5 to 15 nm, preferably 10 nm. The growth process may be, but is not limited to, MOCVD growth.

[0067] In some embodiments, growing the first semiconductor epitaxial layer 20 on the substrate 10 may include: sequentially growing a first buffer layer 52, a first corrosion stop layer 53, a first ohmic contact layer 21, a first confinement layer 22, and a first waveguide layer 23 on the substrate 10, wherein the material of the first ohmic contact layer 21 is GaAs, the material of the first confinement layer 22 is AlInP, and the material of the first waveguide layer 23 is AlGaInP or AlInP. In addition, the thickness of the first buffer layer 51 may be about 200 nm. The conductivity type of the buffer layer 52, the first corrosion stop layer 53, the first ohmic contact layer 21, the first confinement layer 22, and the first waveguide layer 23 may be a first conductivity type, and the first conductivity type may be either N-type or P-type.

[0068] In some embodiments, growing the active layer 30 on the first semiconductor epitaxial layer 20 includes: sequentially growing multiple sub-active layers 31 , each sub-active layer 31 including a quantum barrier layer 311 and a quantum well layer 312 , and doping As and / or Sb elements during the growth of the quantum well layer 312 .

[0069] Specifically, here, the quantum barrier layer 311 and the quantum well layer 312 are alternately formed and can exist in pairs. For example, during the growth process, by controlling the MOCVD growth conditions, such as the total gas flow, temperature, and the ratio of PH3_Top and PH3_Bottom, the high uniformity and high quality of the epitaxial layer are ensured. The growth temperature is maintained at 625°C to 675°C, the growth rate is 0.3μm / H to 0.5μm / H, and the growth pressure is 50mbar. For example, in the growth process of the doped elements in the active layer, the group III source uses trimethyl gallium (TMGa) and trimethyl indium (TMIn), and the group V source uses phosphine (PH) and arsine (AsH 3 ), the ratio of the group V source to the group III source can be 50-150, and the ratio of the group V source to the group III source is controlled within a reasonable range to promote the formation of high-quality crystals. 3 ) is used as the doping source of arsenic As, and no additional introduction is required. The antimony (Sb) element is introduced as a doping source through an antimony-containing MO source such as triethyl antimony (TESb). The doping concentration of As and / or Sb can be adjusted by changing the flow rate of AsH3 and / or TESb.

[0070] Preferably, the thickness of the quantum barrier layer 311 is greater than the thickness of the quantum well layer 312, thereby improving the luminous efficiency of the quantum well layer. The concentration of As and / or Sb doped in each quantum well layer 312 is different, and can be doped in sections. Preferably, the concentration of As and / or Sb doped in the quantum well layer 312 gradually increases from top to bottom. Preferably, the doping concentration of As and / or Sb elements is 1e18 to 5e16. For example, there are five sub-active layers, namely, from bottom to top, the first sub-active layer 31a, the second sub-active layer 31b, the third sub-active layer 31c, the fourth sub-active layer 31d and the fifth sub-active layer 31e; preferably, the concentration range of As and / or Sb elements doped in the quantum well of the first sub-active layer 31a is 1e18-2e18, the concentration range of As and / or Sb elements doped in the quantum well of the second sub-active layer 31b is 5e17-1e18, the concentration range of As and / or Sb elements doped in the quantum well of the third sub-active layer 31c is 1e17-5e17, the concentration range of As and / or Sb elements doped in the quantum well of the fourth sub-active layer 31d is 5e16-1e17, and the concentration range of As and / or Sb elements doped in the quantum well of the fifth sub-active layer 31e is 1e16-5e16. In some embodiments, the material of the quantum barrier layer 311 may be (Al x Ga 1-x ) y In 1-y P, where x is in the range of 0.6 to 1, and y is in the range of 0.4 to 0.6; the material of the quantum well layer 312 is (Al x Ga 1-x ) y In 1-y P, where x ranges from 0 to 0.15 and y ranges from 0.4 to 0.6.

[0071] In some embodiments, growing the second semiconductor epitaxial layer 40 on the active layer 30 includes: sequentially growing a second waveguide layer 21, a second confinement layer 22, a second transition layer 23, and a second window layer 24 on the active layer 30; in some embodiments, a second ohmic contact layer 25 is also grown on the second semiconductor epitaxial layer 40; here, the conductivity type of the second waveguide layer 21, the second confinement layer 22, the second transition layer 23, the second window layer 24, and the second ohmic contact layer 25 is the second conductivity type, which can be N-type or P-type. The second conductivity type is different from the first conductivity type. Preferably, the material of the second waveguide layer 21 is AlGaInP or AlInP, the material of the second confinement layer 22 is AlInP, the material of the second transition layer 23 is AlGaInP, the material of the second window layer 24 is GaP, and the material of the second ohmic contact layer 25 is GaP.

[0072] In the manufacturing method of the epitaxial structure provided in the present application, the first semiconductor epitaxial layer, the active layer, and the second semiconductor epitaxial layer are grown on the substrate 10 using MOCVD growth technology, and As and / or Sb elements are doped during the growth of the active layer to form an active layer with a disordered crystal structure, thereby improving the luminous efficiency of the epitaxial structure. In addition, by adopting segmented doping, the difference in the bandgap width of the quantum well layer is corrected, so that the luminous wavelength is more consistent, thereby further improving the luminous efficiency.

[0073] It should be noted that relational terms in this document, such as "first" and "second", are only used to distinguish an entity or operation from another entity or operation, and do not require or imply any actual relationship or order between these entities or operations. In addition, the words "include", "have" and "include" and other similar forms are intended to be equivalent in meaning and are open-ended, and one or more items following any of these words are not meant to be an exhaustive list of such one or more items, or to be limited to the one or more items listed.

[0074] As used herein, unless expressly stated otherwise, the term "or" encompasses all possible combinations unless not feasible. For example, if a component is stated to include A or B, then unless expressly stated otherwise or not feasible, the component may include A, or B, or A and B. As a second example, if a component is stated to include A, B, or C, then unless expressly stated otherwise or not feasible, the component may include A, or B, or C, or A and B, or A and C, or B and C, or A and B and C.

[0075] In the foregoing description, embodiments have been described with reference to many specific details, which may vary depending on the implementation. Certain changes and modifications may be made to the described embodiments. In view of the description and practice of the present application disclosed herein, other embodiments will be clear to those skilled in the art. The description and examples are intended to be considered as merely exemplary, and the true scope and spirit of the present application are indicated by the following claims. The order of steps shown in the drawings is also intended to be used for illustrative purposes only and is not intended to be limited to any particular order of steps. Therefore, it will be appreciated by those skilled in the art that these steps may be performed in different orders while implementing the same method.

[0076] In the drawings and the specification, exemplary embodiments have been disclosed. However, many variations and modifications may be made to these embodiments. Therefore, although specific terms are employed, they are used only in a general and descriptive sense and not for the purpose of limitation.

Claims

1. An epitaxial structure, characterized in that: include: Multiple sub-active layers; wherein each sub-active layer is doped with doping elements of different concentrations.

2. The epitaxial structure according to claim 1, characterized in that: The doping concentration in the multiple active sub-layers increases from top to bottom.

3. The epitaxial structure according to claim 2, characterized in that: The doping concentration of the doping element is 1e18-5e16.

4. The epitaxial structure according to claim 3, characterized in that: The active layer includes five sub-active layers, which are, from bottom to top, a first sub-active layer, a second sub-active layer, a third sub-active layer, a fourth sub-active layer and a fifth sub-active layer. The concentration range of As and / or Sb elements doped in the quantum well in the first sub-active layer is 1e18 to 2e18, the concentration range of As and / or Sb elements doped in the quantum well in the second sub-active layer is 5e17 to 1e18, the concentration range of As and / or Sb elements doped in the quantum well in the third sub-active layer is 1e17 to 5e17, the concentration range of As and / or Sb elements doped in the quantum well in the fourth sub-active layer is 5e16 to 1e17, and the concentration range of As and / or Sb elements doped in the quantum well in the fifth sub-active layer is 1e16 to 5e16.

5. The epitaxial structure according to claim 1, characterized in that: The doping element is As and / or Sb element.

6. The epitaxial structure according to claim 1, characterized in that: Each sub-active layer includes a quantum barrier layer and a quantum well layer; the doping element is doped in the quantum well layer.

7. The epitaxial structure according to claim 6, characterized in that: The thickness of the quantum barrier layer is greater than the thickness of the quantum well layer.

8. The epitaxial structure according to claim 6, characterized in that: The material of the quantum barrier layer is (Al x Ga 1-x ) y In 1-y P, wherein the range of x is 0.6-1, the range of y is 0.4-0.6, and the thickness of the quantum barrier layer is in the range of 10nm-40nm.

9. The epitaxial structure according to claim 6, characterized in that: The material of the quantum well layer is (Al x Ga 1-x ) y In 1-y P, wherein the range of x is 0-0.15, the range of y is 0.4-0.6, and the thickness of the quantum well layer is 2nm-10nm.

10. The epitaxial structure according to claim 1, characterized in that: The epitaxial structure comprises a substrate, a first semiconductor epitaxial layer, an active layer, and a second semiconductor epitaxial layer which are arranged in sequence from bottom to top; the first semiconductor epitaxial layer and the second semiconductor epitaxial layer have different conductivity types.

11. The epitaxial structure according to claim 10, characterized in that: The substrate is a first conductive type GaAs substrate or a substrate having the same crystal type as GaAs; or, the substrate is Ge or a substrate having the same crystal type as Ge.

12. The epitaxial structure according to claim 11, characterized in that: The crystal orientation is (100) <111> A is a first conductive type GaAs substrate of 2 to 15 degrees; or, Ge or a substrate having the same crystal type as Ge has a crystal orientation of (100) <111> 2°, 6° or 9°.

13. The epitaxial structure according to claim 12, characterized in that: The substrate also has a nucleation layer.

14. The epitaxial structure according to claim 1, characterized in that: The first semiconductor epitaxial layer includes, from top to bottom, a first waveguide layer, a first confinement layer and a first ohmic contact layer.

15. The epitaxial structure according to claim 1, characterized in that: The bottom of the first ohmic contact layer also includes a corrosion stop layer and a buffer layer.

16. The epitaxial structure according to claim 15, characterized in that: The nucleation layer is made of a material that matches the crystal lattice of the buffer layer.

17. The epitaxial structure according to claim 15, characterized in that: The material of the nucleation layer is GaInP or AlGaInP.

18. The epitaxial structure according to claim 15, characterized in that: The material of the buffer layer is GaAs, the material of the first corrosion stop layer is AlGaInP, the material of the first ohmic contact layer is GaAs, the material of the first confinement layer is AlInP, and the material of the first waveguide layer is AlGaInP or AlInP.

19. The epitaxial structure according to claim 1, characterized in that: The second semiconductor epitaxial layer includes, from bottom to top, a second waveguide layer, a second confinement layer, a second transition layer, a second window layer and a second ohmic contact layer.

20. The epitaxial structure according to claim 19, characterized in that The material of the second waveguide layer is AlGaInP or AlInP, the material of the second confinement layer is AlInP, the material of the second transition layer is AlGaInP, the material of the second window layer is GaP, and the material of the second ohmic contact layer is GaP.

21. A micro LED chip structure, characterized in that: It comprises the epitaxial structure of claim 1; and a first electrode structure electrically connected to a first semiconductor epitaxial layer of the epitaxial structure, and a second electrode structure electrically connected to a second semiconductor epitaxial layer.

22. A method for manufacturing an epitaxial structure according to claim 1, characterized in that: include: Step 01: providing the substrate; Step 02: growing the first semiconductor epitaxial layer on the substrate; Step 03: growing the active layer on the first semiconductor epitaxial layer, and doping the doping element during the process of growing the active layer; Step 04: growing the second semiconductor epitaxial layer on the active layer.

23. The method for manufacturing an epitaxial structure according to claim 21, characterized in that: Before step 02, the method further includes: step 011, heating the substrate to a preset temperature.

24. The method for manufacturing an epitaxial structure according to claim 23, characterized in that: The step S011 specifically includes: heating the substrate, with a baking temperature of 650° C. to 800° C. and a baking time of 5 to 30 minutes.

25. The method for preparing an epitaxial structure according to claim 21, characterized in that: In step S03, the growth process of the doping elements in the active layer includes: using group III elements, group V elements and a doping source containing the doping elements, and adjusting the concentration of the doping elements by changing the flow rate of the doping source containing the doping elements.

26. The method for preparing an epitaxial structure according to claim 25, characterized in that: The group III sources use trimethyl gallium (TMGa) and trimethyl indium (TMIn), the group V sources use phosphine (PH) and arsine (AsH3), and the ratio of group V source to group III source is 50-150; antimony (Sb) element is introduced as a doping source through an antimony-containing MO source; the doping concentration of As and / or Sb is adjusted by adjusting the flow rate of AsH3 and / or TESb.

27. The method for preparing an epitaxial structure according to claim 21, characterized in that: The growth conditions of the doped elements in the quantum well layer are: the growth temperature is maintained at 625° C. to 725° C., the growth rate is 0.3 μm / h to 0.5 μm / h, and the growth pressure is 50 mbar.

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