LED chip and preparation method thereof

Abstract

The application discloses an LED chip and a preparation method thereof. A first gradual transition layer (AlGa(In)AsP layer) is added between a first type semiconductor layer (AlGaInP layer) and a multi-quantum well active layer (AlGaAs layer), which plays a role of a growth temperature gradual transition layer, effectively reduces the generation of defects and derivatives, makes the switching interface of the AlGaAs layer and the AlGaInP layer clear, and gradually reduces the P component and gradually increases the As component in the first gradual transition layer in the direction from the first type semiconductor layer to the multi-quantum well active layer, so that the first type semiconductor layer and the multi-quantum well active layer are lattice matched, the crystal growth quality of the multi-quantum well active layer is improved, the light emitting efficiency of the LED chip is improved, and the yield is improved. The first gradual transition layer also corresponds to a barrier layer with a larger band gap, which blocks the overflow of electrons from the multi-quantum well active layer, and improves the light emitting efficiency of the LED chip.

Description

Technical Field

[0001] This application relates to the field of light-emitting diode technology, and in particular to an LED chip and its fabrication method. Background Technology

[0002] With the development of semiconductor technology, near-infrared light-emitting diodes (LEDs) have developed rapidly and are now widely used as artificial light sources for plant cultivation, namely LED plant lighting. Compared with traditional plant lighting, LED plant lighting is more energy-efficient and can directly produce the light needed by plants. There are many types of LED plant lighting, which can not only increase the efficiency of plant photosynthesis but also promote the development of inflorescences, seeds, and fruits. For example, the near-infrared light emitted by LEDs can control and accelerate the flowering cycle without being dependent on day and night or seasons, which is of great value for the cultivation of ornamental flowers.

[0003] However, in traditional near-infrared LED chips, the growth quality of the multi-quantum-well active layer is often poor, which increases non-radiative recombination within the multi-quantum-well active layer. The heat generated by non-radiative recombination within the multi-quantum-well active layer can disrupt the operating state of the LED chip, shorten its lifespan, and thus reduce the device's luminous efficiency and yield. Summary of the Invention

[0004] To address the aforementioned technical problems, this application provides an LED chip and its fabrication method to improve the crystal growth quality of the multi-quantum-well active layer in the LED chip, reduce non-radiative recombination within the multi-quantum-well active layer, thereby improving the luminous efficiency and yield of the LED chip.

[0005] To achieve the above objectives, the embodiments of this application provide the following technical solutions:

[0006] An LED chip includes a stacked structure, the stacked structure comprising: a first type semiconductor layer, a first gradient transition layer, a multi-quantum well active layer, and a second type semiconductor layer stacked sequentially;

[0007] The first type of semiconductor layer is an AlGaInP layer;

[0008] The multi-quantum-well active layer includes alternating potential well layers and potential barrier layers, both of which are AlGaAs layers, and the Al composition of the barrier layer is greater than that of the potential well layer.

[0009] The first gradient transition layer is an AlGa(In)AsP layer, and along the direction from the first type semiconductor layer to the multi-quantum well active layer, the P component gradually decreases and the As component gradually increases in the first gradient transition layer.

[0010] Optionally, along the direction from the first type of semiconductor layer to the multi-quantum-well active layer, the P component in the first gradient transition layer gradually decreases to 0%, and the As component gradually increases to 100%.

[0011] Optionally, the second type semiconductor layer is an AlGaInP layer, and the stacked structure further includes a second gradient transition layer located between the multi-quantum well active layer and the second type semiconductor layer. The second gradient transition layer is an AlGa(In)AsP layer, and is located along the direction from the second type semiconductor layer to the multi-quantum well active layer. In the second gradient transition layer, the P component gradually decreases and the As component gradually increases.

[0012] Optionally, along the direction from the second type semiconductor layer to the multi-quantum-well active layer, the P component in the second gradient transition layer gradually decreases to 0%, and the As component gradually increases to 100%.

[0013] Optionally, the Al component in the first gradient process layer ranges from 45% to 60%, including endpoint values;

[0014] The Al component in the second gradient transition layer ranges from 45% to 60%, including the endpoint values.

[0015] Optionally, the Al composition of each potential well layer in the multi-quantum well active layer is greater than 0% and less than 45%.

[0016] The Al composition of each barrier layer in the multi-quantum well active layer is greater than 45% and less than 60%.

[0017] A method for fabricating an LED chip, comprising:

[0018] Provide a first substrate;

[0019] A stacked structure is formed on one side of the first substrate, the formation process of the stacked structure including:

[0020] A first type semiconductor layer is formed on one side of the first substrate, wherein the first type semiconductor layer is an AlGaInP layer;

[0021] A first gradient transition layer is formed on the side of the first type semiconductor layer away from the first substrate. The first gradient transition layer is an AlGa(In)AsP layer. Along the direction away from the first type semiconductor layer, the P component in the first gradient transition layer gradually decreases and the As component gradually increases.

[0022] A multi-quantum-well active layer is formed on the side of the first gradient transition layer away from the first type of semiconductor layer. The multi-quantum-well active layer includes alternating potential well layers and potential barrier layers. Both the potential well layers and the potential barrier layers are AlGaAs layers, and the Al composition of the potential barrier layer is greater than that of the potential well layer.

[0023] A second type semiconductor layer is formed on the side of the multi-quantum-well active layer that is away from the first type semiconductor layer;

[0024] From the side of the stacked structure opposite to the first substrate, the stacked structure is bonded to the second substrate, and the first substrate is removed to achieve substrate transfer.

[0025] Optionally, the growth temperature of the first type of semiconductor layer is a first temperature, and the growth temperature of the multi-quantum well active layer is a second temperature. When the first type of semiconductor layer forms a first gradient transition layer on the side away from the first substrate, the growth temperature of the first gradient transition layer gradually transitions from the first temperature to the second temperature, and the second temperature is greater than the first temperature.

[0026] Optionally, the second type of semiconductor layer is an AlGaInP layer. Specifically, before forming the second type of semiconductor layer, the method further includes:

[0027] A second gradient transition layer is formed on the side of the multi-quantum well active layer away from the first type of semiconductor layer. The second gradient transition layer is an AlGa(In)AsP layer, and along the direction toward the multi-quantum well active layer, the P component gradually decreases and the As component gradually increases.

[0028] Forming a second type semiconductor layer on the side of the multi-quantum-well active layer opposite to the first type semiconductor layer includes:

[0029] A second type semiconductor layer is formed on the side of the second gradient transition layer that is away from the multi-quantum-well active layer.

[0030] Optionally, the growth temperature of the multi-quantum well active layer is a second temperature, and the growth temperature of the second type semiconductor layer is a third temperature. In this method, when a second gradient transition layer is formed on the side of the multi-quantum well active layer away from the first type semiconductor layer, the growth temperature of the second gradient transition layer gradually transitions from the second temperature to the third temperature, and the third temperature is lower than the second temperature.

[0031] Compared with existing technologies, the above technical solution has the following advantages:

[0032] The LED chip provided in this application embodiment includes a stacked structure, which includes a first type semiconductor layer, a first gradient transition layer, a multi-quantum-well active layer, and a second type semiconductor layer stacked sequentially. The first type semiconductor layer is an AlGaInP layer. The alternating well and barrier layers in the multi-quantum-well active layer are both AlGaAs layers, with the Al composition of the barrier layer being greater than that of the well layer. Since In in AlGaInP material is prone to desorption at high temperatures, the AlGaInP layer needs to be grown at a lower temperature, while the AlGaAs layer should be grown at a higher temperature to ensure the migration ability of Al atoms. Growing the AlGaAs layer at low temperatures will significantly reduce the crystal quality of the quantum well interface. Simultaneously, at lower temperatures, deep-level impurity oxygen will form non-radiative recombination centers during the growth of the AlGaAs layer. That is, the growth temperatures of the AlGaInP layer and the AlGaAs layer are different. Therefore, when switching between the growth of the first type semiconductor layer (AlGaInP layer) and the multi-quantum-well active layer (AlGaAs layer), there will be issues related to the growth of AlGaInP and AlGaAs layers. The issue of long temperature transitions complicates the fabrication process of multi-quantum-well active layers, making growth stalls or temperature variations during growth prone to occur. This results in poor crystal growth quality of the multi-quantum-well active layer. In the LED chip provided in this application embodiment, a first gradient transition layer, an AlGa(In)AsP layer, is added between the first semiconductor layer (AlGaInP layer) and the multi-quantum-well active layer (AlGaAs layer). This first gradient transition layer acts as a temperature gradient transition layer, allowing growth at varying temperatures. The growth temperature can gradually transition from the low temperature of AlGaInP layer growth to the high temperature of AlGaAs growth, or vice versa. This reduces the instability caused by the temperature switching between the first semiconductor layer and the multi-quantum-well active layer, protecting the growth of the multi-quantum-well active layer. This improves the crystal growth quality of the multi-quantum-well active layer, reduces non-radiative recombination within the multi-quantum-well active layer, and enhances the luminous efficiency and yield of the LED chip.

[0033] Furthermore, when directly growing the multi-quantum-well active layer (AlGaAs layer) on the first type semiconductor layer (AlGaInP layer), problems such as unclear switching interface, interface derivatives, and easy strain and dislocation causing epitaxial wafer warping can affect the crystal growth quality of the multi-quantum-well active layer. Therefore, in the LED chip provided in this application embodiment, a first gradient transition layer is added between the first type semiconductor layer (AlGaInP layer) and the multi-quantum-well active layer (AlGaAs layer), and the first gradient transition layer is an AlGa(In)AsP layer, thereby effectively reducing the As / P ratio. By switching the introduced stress and defects and reducing the generation of derivatives, the switching interface between the AlGaAs layer and the AlGaInP layer is clear. In the direction from the first type semiconductor layer to the multi-quantum well active layer, the P component in the first gradient transition layer gradually decreases and the As component gradually increases. That is, through the gradual change of the P component and As component in the first gradient transition layer, the lattice matching between the first type semiconductor layer and the multi-quantum well active layer is achieved, which further suppresses the generation of dislocations, improves the crystal growth quality of the multi-quantum well active layer, reduces non-radiative recombination inside the multi-quantum well active layer, and improves the luminous efficiency and yield of the LED chip.

[0034] Furthermore, in the LED chip provided in this application embodiment, the first gradient transition layer added between the first type semiconductor layer (AlGaInP layer) and the multi-quantum well active layer (AlGaAs layer) is an AlGa(In)AsP layer. Since the band gap of the AlGa(In)AsP layer is greater than that of AlGaAs, the first gradient transition layer is also equivalent to a barrier layer with a band gap larger than that of the barrier layer in the multi-quantum well active layer. This can prevent electrons from overflowing from the multi-quantum well active layer, improve the recombination of electrons and holes inside the multi-quantum well active layer, and further improve the luminous efficiency of the LED chip.

[0035] Therefore, in the LED chip provided in this application embodiment, by adding a first gradient transition layer (AlGa(In)AsP layer) between the first type semiconductor layer (AlGaInP layer) and the multi-quantum well active layer (AlGaAs layer), the influence of growth temperature conversion and material matching on the growth quality of the multi-quantum well active layer is eliminated, making the growth process of the multi-quantum well active layer simpler, improving the crystal quality of the multi-quantum well active layer and subsequent epitaxial layers, and improving the luminous efficiency and yield of the LED chip. Attached Figure Description

[0036] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0037] Figure 1 This is a schematic diagram of the epitaxial structure of an existing near-infrared LED chip;

[0038] Figure 2 This is a schematic diagram of the epitaxial structure of an LED chip provided in one embodiment of this application;

[0039] Figure 3 This is a schematic diagram of the epitaxial structure of an LED chip provided in another embodiment of this application;

[0040] Figure 4 This is a schematic diagram of the epitaxial structure of an LED chip provided in yet another embodiment of this application;

[0041] Figure 5 This is a schematic diagram of the epitaxial structure of an LED chip provided in another embodiment of this application;

[0042] Figure 6 This is a schematic flowchart illustrating a method for fabricating an LED chip according to an embodiment of this application.

[0043] Figures 7(a)-7(i) This is a schematic diagram of the device structure corresponding to each process step in the LED chip fabrication method provided in the embodiments of this application;

[0044] Figure 8 This is a schematic flowchart illustrating a method for fabricating an LED chip according to another embodiment of this application. Detailed Implementation

[0045] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0046] Many specific details are set forth in the following description in order to provide a full understanding of this application. However, this application may also be implemented in other ways different from those described herein. Those skilled in the art can make similar extensions without departing from the spirit of this application. Therefore, this application is not limited to the specific embodiments disclosed below.

[0047] Secondly, this application provides a detailed description in conjunction with schematic diagrams. When detailing the embodiments of this application, for ease of explanation, the cross-sectional views illustrating the device structure may be partially enlarged, not adhering to the usual scale. Furthermore, the schematic diagrams are merely examples and should not limit the scope of protection of this application. In addition, actual fabrication should include three-dimensional spatial dimensions of length, width, and depth.

[0048] Figure 1 A schematic diagram of the epitaxial structure of an existing near-infrared LED chip is given, from Figure 1 As can be seen, existing near-infrared LED chips include N-type semiconductor layer 01, multi-quantum-well active layer 02, and P-type semiconductor layer 03 stacked sequentially. In order to improve the brightness and luminous efficiency of near-infrared LED chips, N-type semiconductor layer 01 and P-type semiconductor layer 03 mostly adopt AlGaInP layers, which absorb less near-infrared light. Multi-quantum-well active layer 02 includes alternating potential well layer 021 and potential barrier layer 022, both of which adopt AlGaAs layers.

[0049] The inventors discovered that while high temperatures help suppress the incorporation of O impurities during AlGaInP layer growth, excessively high temperatures can cause In to desorb easily, leading to In re-evaporation. Therefore, the growth temperature of AlGaInP layers should not be too high, resulting in a relatively narrow growth temperature window. AlGaAs layers, on the other hand, should be grown at higher temperatures to ensure the migration ability of Al atoms. Higher temperatures also reduce the incorporation of background doping in the AlGaAs layer. Growing AlGaAs layers at low temperatures significantly reduces the crystal quality of the quantum well interface. Furthermore, at lower temperatures, deep-level impurity oxygen forms non-radiative recombination centers during AlGaAs layer growth. Therefore, the growth temperature of AlGaAs layers is higher, meaning the growth temperatures of AlGaAs and AlGaInP layers differ. Consequently, growing AlGaAs layers on AlGaInP layers, or vice versa, presents the problem of temperature transitions, complicating the fabrication process for multi-quantum-well active layers and increasing the risk of growth stalls or temperature fluctuations during growth, ultimately leading to poor crystal growth quality. As the radiative recombination region for charge carriers, the growth quality of the multi-quantum-well active layer and the recombination efficiency of the charge carriers significantly affect the luminous efficiency and lifespan of LED chips. Poor crystal growth quality in the multi-quantum-well active layer will increase non-radiative recombination within the multi-quantum-well active layer. Non-radiative recombination and subsequent heat generation will disrupt the operating state of the LED chip, shorten its lifespan, and thus reduce the luminous efficiency and yield of the device.

[0050] Furthermore, when growing an AlGaInP layer on an AlGaAs layer, the interface is relatively flat. However, when growing an AlGaAs layer on an AlGaInP layer, due to the memory effect of In and the contamination caused by As / P substitution, the switching interface is prone to be unclear. InGaAlAs(P) derivatives may also appear at the interface, which will affect the growth quality of the multi-quantum-well active layer and the growth quality of subsequent film layers, increase non-radiative recombination inside the multi-quantum-well active layer, and reduce the luminous efficiency and yield of the device.

[0051] In addition, when growing AlGaAs layers on AlGaInP layers, some strain and dislocations are easily generated, causing the epitaxial wafer to warp during the growth process and resulting in abnormal appearance of the epitaxial wafer. This will also affect the crystal growth quality of the multi-quantum-well active layer, increase non-radiative recombination inside the multi-quantum-well active layer, and reduce the luminous efficiency and yield of the device.

[0052] In view of this, embodiments of this application provide an LED chip, Figure 2 A schematic diagram of the epitaxial structure of the LED chip provided in the embodiments of this application is given, from which... Figure 2 As can be seen, the LED chip includes a stacked structure 100, which includes: a first type semiconductor layer 10, a first gradient transition layer 20, a multi-quantum well active layer 30, and a second type semiconductor layer 40 stacked sequentially.

[0053] Among them, the first type of semiconductor layer 10 is an AlGaInP layer;

[0054] The multi-quantum-well active layer 30 includes alternating potential well layers 31 and potential barrier layers 32. Both potential well layers 31 and potential barrier layers 32 are AlGaAs layers, and the Al composition of the potential barrier layer 32 is greater than that of the potential well layer 31.

[0055] The first gradient transition layer 20 is an AlGa(In)AsP layer, which can be either an AlGaAsP layer or an AlGaInAsP layer. Along the direction from the first type semiconductor layer 10 to the multi-quantum well active layer 30, the P component in the first gradient transition layer 20 gradually decreases and the As component gradually increases.

[0056] In this embodiment, both the potential well layer 31 and the barrier layer 32 in the multi-quantum-well active layer 30 are AlGaAs layers. For example, the potential well layer 31 is Al a Ga 1-a As layer, barrier layer 32 is Al b Ga 1-bThe As layer, where a and b satisfy: 0 < a < b < 1. This is because in the AlGaAs material, the larger the Al component, the larger its bandgap. Since a < b, the bandgap of the quantum well layer 32 is smaller than that of the barrier layer 31, so that electrons are confined in each quantum well layer 31 and recombine with holes in each quantum well layer 31 to emit light. Moreover, since both the quantum well layer 31 and the barrier layer 32 in the multi-quantum well active layer are AlGaAs layers and the crystal growth materials are the same, the growth interface between the quantum well layer 31 and the barrier layer 32 can be clearly switched, which is beneficial to improving the crystal growth quality of the multi-quantum well active layer, the light-emitting efficiency and the production yield of the LED chip.

[0057] It should be noted that Figure 2 only one set of the quantum well layer 31 and the barrier layer 32 is drawn. In fact, there are multiple sets of the quantum well layer 31 and the barrier layer 32 in the multi-quantum well active layer 30.

[0058] In the multi-quantum well active layer 30, an adjacent quantum well layer 31 and a barrier layer 32 form a period. Optionally, the value range of the number of periods can be 5 to 15, including the end values, that is, the number of pairs of the quantum well layer 31 and the barrier layer 32 is 5 to 15, but this application does not limit this, and it depends on the specific situation.

[0059] To improve the brightness and light-emitting efficiency of the LED chip, the first-type semiconductor layer 10 needs to use a material with less absorption of the light emitted by the multi-quantum well active layer 30. Considering that the AlGaInP layer has less absorption of near-infrared light, in this embodiment, the first-type semiconductor layer 10 is selected as the AlGaInP layer.

[0060] However, due to the different growth temperatures of the AlGaInP and AlGaAs layers, a temperature transition issue arises when switching between the growth of the first semiconductor layer 10 (AlGaInP layer) and the multi-quantum-well active layer 30 (AlGaAs layer). This complicates the process of the multi-quantum-well active layer, making it prone to growth stalls or temperature changes during growth, resulting in poor crystal growth quality. In the LED chip provided in this embodiment, a first gradient transition layer 20 is added between the first semiconductor layer 10 (AlGaInP layer) and the multi-quantum-well active layer 30 (AlGaAs layer). The first gradient transition layer 20 is an AlGa(In)AsP layer, which serves as a temperature gradient transition layer. The first gradient transition layer can be grown at varying temperatures, with its growth temperature gradually changing from the low temperature of growing AlGaInP to the high temperature of growing AlGaAs, or from the high temperature of growing AlGaAs to the low temperature of growing AlGaInP. This reduces the instability caused by the temperature switching between the first type semiconductor layer 10 and the multi-quantum well active layer 30, and protects the growth of the multi-quantum well active layer. This improves the crystal growth quality of the multi-quantum well active layer, reduces non-radiative recombination inside the multi-quantum well active layer, and improves the luminous efficiency and yield of the LED chip.

[0061] It should be noted that this application does not limit the growth order of the first type semiconductor layer 10 and the multi-quantum well active layer 30; it depends on the specific circumstances.

[0062] Optionally, in one embodiment of this application, a first type semiconductor layer 10 (AlGaInP layer) is first grown, followed by the sequential growth of a first gradient transition layer 20 (AlGa(In)AsP layer) and a multi-quantum well active layer 30 (AlGaAs layer).

[0063] Optionally, in another embodiment of this application, a multi-quantum well active layer 30 (AlGaAs layer) is first grown, followed by the sequential growth of a first gradient transition layer 20 (AlGa(In)AsP layer) and a first type semiconductor layer 10 (AlGaInP layer).

[0064] Whether the first type semiconductor layer 10 (AlGaInP layer) is grown on the first type semiconductor layer 10 (AlGaInP layer) or the first type semiconductor layer 10 (AlGaInP layer) is grown on the first type semiconductor layer 30 (AlGaInP layer), the first gradient transition layer 20 (AlGa(In)AsP layer) can serve as a temperature gradient transition layer.

[0065] Furthermore, when the multi-quantum well active layer 30 (AlGaAs layer) is directly grown on the first type semiconductor layer 10 (AlGaInP layer), there are still problems such as unclear switching interface between AlGaInP layer and AlGaAs layer, appearance of derivatives at the interface, and easy generation of strain and dislocations causing epitaxial wafer warping, which affect the crystal growth quality of the multi-quantum well active layer. Therefore, in the LED chip provided in the embodiments of this application, a first gradient transition layer 20 is added between the first type semiconductor layer 10 (AlGaInP layer) and the multi-quantum well active layer 30 (AlGaAs layer), and the first gradient transition layer 20 is an AlGa(In)AsP layer, thereby effectively reducing the stress and defects introduced by As / P switching, reducing the generation of derivatives, and making the switching interface between AlGaAs layer and AlGaInP layer clear.

[0066] In this embodiment, the first gradient transition layer 20 is an AlGa(In)AsP layer, specifically represented as Al x Ga 1-x (In)As y P 1-y Layer, which can be Al x Ga 1-x As y P 1-y Layers, or Al x Ga 1-x InAs y P 1-y Furthermore, along the direction from the first type semiconductor layer 10 (AlGaInP layer) to the multi-quantum well active layer 30 (AlGaAs layer), the As component y in the first gradient transition layer 20 gradually increases, while the P component (1-y) gradually decreases. That is, through the gradual change of the P component and the As component in the first gradient transition layer 20, the first gradient transition layer 20 gets closer to the multi-quantum well active layer 30 and is more matched with the material of the multi-quantum well active layer 30. This makes the first type semiconductor layer 10 and the multi-quantum well active layer 30 lattice matched, suppresses the generation of dislocations, further improves the crystal growth quality of the multi-quantum well active layer, reduces non-radiative recombination inside the multi-quantum well active layer, and improves the luminous efficiency and yield of the LED chip.

[0067] In this embodiment, the first gradient transition layer 20 is an AlGa(In)AsP layer. Specifically, the amount of As source (AsH3 source) and P source (PH3 source) provided can be controlled to achieve a gradual decrease in the P composition and a gradual increase in the As composition along the direction from the first type semiconductor layer 10 to the multi-quantum well active layer 30 in the first gradient transition layer 20.

[0068] Furthermore, in the LED chip provided in this application embodiment, the first gradient transition layer 20 added between the first type semiconductor layer 10 (AlGaInP layer) and the multi-quantum well active layer 30 (AlGaAs layer) is an AlGa(In)AsP layer. Since the band gap of the AlGa(In)AsP layer is greater than that of the AlGaAs layer, the first gradient transition layer 20 is also equivalent to a barrier layer with a band gap larger than that of the barrier layer 32 in the multi-quantum well active layer 30. This can prevent electrons from overflowing from the multi-quantum well active layer 30, improve the recombination of electrons and holes in the multi-quantum well active layer, and further improve the luminous efficiency of the LED chip.

[0069] Therefore, in the LED chip provided in this application embodiment, by adding a first gradient transition layer 20 (AlGa(In)AsP layer) between the first type semiconductor layer 10 (AlGaInP layer) and the multi-quantum well active layer 30 (AlGaAs layer), the influence of growth temperature conversion and material matching on the growth quality of the multi-quantum well active layer 30 can be eliminated, making the growth process of the multi-quantum well active layer 30 simpler, improving the crystal quality of the multi-quantum well active layer 30 and subsequent epitaxial layers, and improving the luminous efficiency and yield of the LED chip.

[0070] It should be noted that, as mentioned above, when directly growing an AlGaAs layer on an AlGaInP layer, due to the segregation of In at high temperatures, rapid temperature switching may cause the formation of InGaAlAs(P) derivatives at the interface. However, the elemental composition of these derivatives is disordered, and their positions are uncontrollable. Therefore, these InGaAlAs(P) derivatives not only do not benefit the material matching and growth temperature matching between the first type semiconductor layer 10 (AlGaInP layer) and the multi-quantum well active layer 30 (AlGaAs layer), but also exacerbate the mismatch between materials and growth temperature. In the LED chip provided in the embodiments of this application, in the first type semiconductor layer 10 (AlGaInP layer), Between the nP layer and the multi-quantum-well active layer 30 (AlGaAs layer), a first gradient transition layer (AlGa(In)AsP layer) with gradually changing As and P compositions is added. The first gradient transition layer can be grown at varying temperatures, gradually changing from the low temperature of growing AlGaInP layer to the high temperature of growing AlGaAs. This prevents the loss of In composition, makes the growth interface clear, and serves as a temperature gradient transition layer. On the other hand, it makes the material lattice matched, reduces stress and defects, and reduces the generation of derivatives. This improves the crystal growth quality of the quantum well active layer, reduces non-radiative recombination inside the multi-quantum-well active layer, and improves the luminous efficiency and yield of LED chips.

[0071] In this embodiment, the first semiconductor layer 10 can be an N-type semiconductor layer and the second semiconductor layer 20 can be a P-type semiconductor layer, but this application does not limit this and it depends on the specific situation.

[0072] In this embodiment, the first gradient transition layer 10 can be an undoped AlGa(In)AsP layer. Optionally, the thickness of the first gradient transition layer 10 can range from 0.01 μm to 0.05 μm, but this application does not limit this value and it depends on the specific circumstances.

[0073] Based on the above embodiments, in one embodiment of this application, along the direction from the first type semiconductor layer 10 to the multi-quantum well active layer 30, the P component in the first gradient transition layer 20 gradually decreases to 0%, and the As component gradually increases to 100%, that is, the side of the first gradient transition layer 20 (AlGa(In)AsP layer) closer to the multi-quantum well active layer 30 (AlGaAs layer) is more matched with the multi-quantum well active layer 30 (AlGaAs layer).

[0074] To further improve the brightness and luminous efficiency of the LED chip, the second semiconductor layer 40 also needs to be made of a material that absorbs less light emitted from the multi-quantum-well active layer. Considering that the AlGaInP layer absorbs less near-infrared light, it is optional that, in one embodiment of this application, the second semiconductor layer is also an AlGaInP layer. However, since the growth temperatures of the AlGaInP layer and the AlGaAs layer are different, there will be a problem of growth temperature transition when switching between the growth of the multi-quantum-well active layer 30 (AlGaAs layer) and the second semiconductor layer 40 (AlGaInP layer). This makes the process of the multi-quantum-well active layer more complex and prone to growth stalls or temperature changes during growth, resulting in poor crystal growth quality of the multi-quantum-well active layer. Based on this, in this embodiment, if... Figure 3 As shown, the stacked structure 100 further includes a second gradient transition layer 50 located between the multi-quantum well active layer 30 and the second type semiconductor layer 40. The second gradient transition layer 50 is an AlGa(In)AsP layer, that is, it can be an AlGaAsP layer or an AlGaInAsP layer, and it is located along the direction from the second type semiconductor layer 40 to the multi-quantum well active layer 30. The P component in the second gradient transition layer 50 gradually decreases and the As component gradually increases.

[0075] In this embodiment, a second gradient transition layer 50 is added between the multi-quantum well active layer 30 (AlGaAs layer) and the second type semiconductor layer 40 (AlGaInP layer). The second gradient transition layer 50 is an AlGa(In)AsP layer, which also serves as a growth temperature gradient transition layer. The second gradient transition layer can be grown at varying temperatures, with its growth temperature gradually changing from the low temperature for growing AlGaInP layer to the high temperature for growing AlGaAs, or vice versa. This reduces the instability caused by the temperature switching between the multi-quantum well active layer 30 and the second type semiconductor layer 40, protecting the growth of the multi-quantum well active layer, thereby improving the crystal growth quality of the multi-quantum well active layer, reducing non-radiative recombination within the multi-quantum well active layer, and improving the luminous efficiency and yield of the LED chip.

[0076] In this embodiment, the second gradient transition layer 50 is an AlGa(In)AsP layer, specifically represented as Al m Ga 1-m (In)As n P 1-n Layer, which can be Al m Ga 1-m As n P 1-n Layers, or Al m Ga 1-m InAs n P 1-n Furthermore, along the direction from the second type semiconductor layer 40 (AlGaInP layer) to the multi-quantum well active layer 30 (AlGaAs layer), the As component n in the second gradient transition layer 50 gradually increases, while the P component (1-n) gradually decreases. In other words, along the direction from the multi-quantum well active layer 30 (AlGaAs layer) to the second type semiconductor layer 40 (AlGaInP layer), the As component n in the second gradient transition layer 50 gradually decreases, while the P component (1-n) gradually increases. Thus, through the gradual change of the P component and the As component in the second gradient transition layer 20, the second gradient transition layer 50 becomes closer to the multi-quantum well active layer 30 and more compatible with the material of the multi-quantum well active layer 30. This results in lattice matching between the second type semiconductor layer 40 and the multi-quantum well active layer 30, which is beneficial to the crystal growth quality of the multi-quantum well active layer and the second type semiconductor layer.

[0077] In this embodiment, the second gradient transition layer 50 is an AlGa(In)AsP layer. Specifically, by controlling the amount of As source (AsH3 source) and P source (PH3 source) provided, the P component in the second gradient transition layer 50 gradually decreases and the As component gradually increases along the direction from the second type semiconductor layer 40 to the multi-quantum well active layer 30. That is, along the direction from the multi-quantum well active layer 30 to the second type semiconductor layer 40, the As component in the second gradient transition layer 50 gradually decreases and the P component gradually increases.

[0078] In this embodiment, a stacked structure 100 can be formed by sequentially growing a first gradient transition layer 20 (AlGa(In)AsP layer), a multi-quantum well active layer 30 (AlGaAs layer), a second gradient transition layer 50 (AlGa(In)AsP layer), and a second type semiconductor layer 40 (AlGaInP layer) on a first type semiconductor layer 10 (AlGaInP layer). Alternatively, a second gradient transition layer 50 (AlGa(In)AsP layer), a multi-quantum well active layer 30 (AlGaAs layer), a first gradient transition layer 20 (AlGa(In)AsP layer), and a second type semiconductor layer 10 (AlGaInP layer) can be formed on a second type semiconductor layer 40 (AlGaInP layer). The multi-quantum well active layer 30 (AlGaAs layer) forms a stacked structure 100, in which gradient transition layers are provided on both sides of the multi-quantum well active layer 30 (AlGaAs layer). These transition layers act as growth temperature gradient transition layers between the AlGaAs layer and the AlGaInP layer. Furthermore, in both gradient transition layers, the P composition gradually decreases and the As composition gradually increases as they approach the multi-quantum well active layer 30 (AlGaAs layer). This makes the switching interface between the AlGaAs layer and the AlGaInP layer clearer, the lattice more matched, reduces stress and defects, reduces the generation of derivatives, further improves the crystal growth quality of the multi-quantum well active layer, reduces non-radiative recombination inside the multi-quantum well active layer, and improves the luminous efficiency and yield of the LED chip.

[0079] In this embodiment, the second gradient transition layer 50 can be an undoped AlGa(In)AsP layer. Optionally, the thickness of the second gradient transition layer 50 can range from 0.01 μm to 0.05 μm, but this application does not limit it and it depends on the specific situation.

[0080] Based on the above embodiments, optionally, in one embodiment of this application, along the direction from the second type semiconductor layer 40 to the multi-quantum well active layer 30, the P component in the second gradient transition layer 50 gradually decreases to 0%, and the As component gradually increases to 100%, that is, the side of the second gradient transition layer 50 (AlGa(In)AsP layer) closer to the multi-quantum well active layer 30 (AlGaAs layer) is more matched with the multi-quantum well active layer (AlGaAs layer).

[0081] Optionally, in one embodiment of this application, the Al component in the first gradient process transition layer 20 ranges from 45% to 60%, including endpoint values;

[0082] The Al content in the second gradient transition layer ranges from 45% to 60%, including the endpoint values.

[0083] Since a larger Al content results in a larger bandgap in AlGa(In)AsP layer materials, in this embodiment, by setting the Al content in the first gradient transition layer 20 and the second gradient transition layer 50, the bandgap of the first gradient transition layer 20 and the second gradient transition layer 50 is made larger than the bandgap of the barrier layer 32 (AlGaAs layer) in the multi-quantum well active layer 30. This makes the first gradient transition layer 20 and the second gradient transition layer 50 act as barrier layers with a larger bandgap than the barrier layer 32 on both sides of the multi-quantum well active layer 30. This can block electrons from escaping from the multi-quantum well active layer 30 from both sides, improve the recombination of electrons and holes inside the multi-quantum well active layer, and further improve the luminous efficiency of the LED chip.

[0084] Based on any of the above embodiments, optionally, in one embodiment of this application, the Al composition of each potential well layer 31 in the multi-quantum well active layer 30 is greater than 0% and less than 45%.

[0085] The Al composition of each barrier layer 32 in the multi-quantum well active layer 30 is greater than 45% and less than 60%.

[0086] Optionally, the total thickness of the multi-quantum-well active layer 30 can range from 0.5 μm to 1.5 μm, including the endpoint values, but this application does not limit it and it depends on the specific circumstances.

[0087] In practical applications, such as Figure 4 As shown, the stacked structure 100 further includes a current spreading layer 60 located on the side of the first type semiconductor layer 10 opposite to the multi-quantum-well active layer 30, so that the current can spread uniformly within the current spreading layer 60, resulting in more uniform luminous intensity of the LED chip and increasing the luminous area of ​​the LED chip. Optionally, the current spreading layer can be an AlGaInP layer.

[0088] Based on this, in order to form a good ohmic contact on the side of the first type semiconductor layer 10 away from the multi-quantum-well active layer 30, such as Figure 4 As shown, the stacked structure 100 also includes:

[0089] The ohmic contact layer 70 is located on the side of the current spreading layer 60 away from the first type semiconductor layer 10. The ohmic contact layer 70 can be a GaAs layer.

[0090] And an electrode stabilizing layer 80 located between the current spreading layer 60 and the ohmic contact layer 70, the electrode stabilizing layer 80 may be a GaInP layer to improve the push-pull force in LED chip reliability verification.

[0091] Similarly, to form a good ohmic contact on the side of the second type semiconductor layer 40 away from the multi-quantum-well active layer 30, such as Figure 5 As shown, the stacked structure 100 also includes:

[0092] A transition layer 90 is located on the side of the second type semiconductor layer 40 away from the multi-quantum well active layer 30. The transition layer 90 can be a GaInP layer.

[0093] And a window layer 91 located on the side of the transition layer 90 away from the second type semiconductor layer 40. The window layer 91 can be a GaP layer with a highly doped surface, thereby forming a good ohmic contact with the electrode corresponding to the second type semiconductor layer 40, and allowing the current to spread uniformly within the GaP window layer 91, making the luminous intensity of the LED chip more uniform, and also increasing the luminous area of ​​the LED chip.

[0094] It should be noted that in practical applications, the aforementioned stacked structure is typically grown on a first substrate. To ensure lattice matching between the stacked structure 100 and the first substrate, a buffer layer and an etching stop layer are first grown on the first substrate. For example, if the first substrate is a GaAs substrate, a GaAs buffer layer and a GaInP etching stop layer are first grown on the first substrate, and then further growth is performed on the stacked structure 100. Figure 5 The images show the various film layers from bottom to top.

[0095] After the stacked structure 100 is grown, it is bonded to the second substrate from the side of the stacked structure 100 away from the first substrate, and the first substrate is removed to achieve substrate transfer. Optionally, the second substrate 002 can be a silicon substrate, germanium substrate, or sapphire substrate, etc., but this application does not limit it and it depends on the specific circumstances.

[0096] After substrate transfer, a first electrode is formed on the side of the stacked structure away from the second substrate, and a second electrode is formed on the side of the second substrate away from the stacked structure, thus obtaining the LED chip structure.

[0097] This application also provides a method for fabricating an LED chip, such as... Figure 6 As shown, the method includes:

[0098] S100: As shown in FIG7(a), a first substrate 110 is provided.

[0099] Optionally, the first substrate 110 is a GaAs substrate.

[0100] Before forming the subsequent stacked structure 100, in order for the stacked structure 100 to match the lattice of the first substrate 110, as shown in FIG7(b), a buffer layer 111 and an etching stop layer 112 need to be formed on the first substrate 110.

[0101] Specifically, a first substrate 110 is placed in a reaction chamber, and an AsH3 source and a TMGa source are introduced. A GaAs buffer layer 111 with a thickness of 0.2 μm to 0.4 μm is grown in a temperature range of 650℃ to 750℃. This layer can be doped with an N-type doping source (which can be a Si / Te source), and its carrier concentration can be in the range of 8E17 / cm³. 3 -2E18 / cm 3 .

[0102] Next, the reaction chamber temperature is controlled within the range of 650℃-720℃. The AsH3 source is switched to a PH3 source, and a TMIn source is introduced to grow a GaInP etching stop layer 112 with a thickness between 0.05μm and 0.2μm. An N-type doping source (such as a Si / Te source) can be incorporated, with a carrier concentration of 7E17 / cm³. 3 -2E18 / cm 3 .

[0103] S200: A stacked structure 100 is formed on one side of the first substrate 110.

[0104] Specifically, the formation process of the laminated structure 100 includes:

[0105] S210: As shown in FIG7(c), a first type semiconductor layer 10 is formed on one side of the first substrate 110. The first type semiconductor layer 10 is an AlGaInP layer.

[0106] Specifically, metal-organic chemical vapor deposition (MOCVD) is used to maintain the reaction chamber temperature at 650℃-750℃, and TMAl, TMGa, TMIn, and PH3 sources are introduced to form an AlGaInP layer as a type I semiconductor layer on one side of the first substrate. The thickness can be 0.2μm-0.5μm, and an N-type doping source (such as a Si / Te source) can be incorporated, with a carrier concentration of 1E18 / cm³. 3 -5E18 / cm 3 .

[0107] In practical applications, the formation process of the stacked structure 100 between the formation of the first type semiconductor layer 10 typically includes:

[0108] S211: As shown in FIG7(c), an ohmic contact layer 70, an electrode stabilizing layer 80 and a current spreading layer 60 are sequentially formed on one side of the first substrate 110 so as to form a first type semiconductor layer on the side of the current spreading layer 60 opposite to the first substrate 110.

[0109] At this point, the current can spread uniformly within the current spreading layer 60, resulting in more uniform luminous intensity of the LED chip and increasing the light-emitting area of ​​the LED chip. Optionally, the current spreading layer can be an AlGaInP layer.

[0110] Specifically, the reaction chamber temperature is maintained at 650℃-750℃, and a TMGa source and an AsH3 source are introduced to grow a GaAs ohmic contact layer 70 with a thickness of 0.05μm-0.1μm. An N-type doping source (such as a Si / Te source) can be incorporated, and the carrier concentration can be 7E17 / cm³. 3 -3E18 / cm 3 .

[0111] Then, the reaction chamber temperature is maintained at 650℃-720℃, and a TMGa source, a TMIn source, and a PH3 source are introduced to grow a GaInP electrode stabilization layer 80 with a thickness between 0.01μm and 0.15μm. An N-type doping source (such as a Si / Te source) can be incorporated, with a carrier concentration of 7E17 / cm³. 3 -2E18 / cm 3 .

[0112] Next, the reaction chamber temperature is adjusted to 650℃-750℃, and TMAl, TMGa, TMIn, and PH3 sources are introduced to grow AlGaInP material as an N-type current extension layer 60. Its thickness can be between 3μm and 5μm. An N-type doping source (such as a Si / Te source) can be incorporated, with an Al content between 30% and 100% and a carrier concentration of 8E17 / cm³. 3 -3E18 / cm 3 .

[0113] S220: As shown in Figure 7(d), a first gradient transition layer 20 is formed on the side of the first type semiconductor layer 10 away from the first substrate 110. The first gradient transition layer 20 is an AlGa(In)AsP layer, and along the direction away from the first type semiconductor layer 10, the P component in the first gradient transition layer 20 gradually decreases and the As component gradually increases.

[0114] In this embodiment, the first gradient transition layer 20 is an AlGa(In)AsP layer, specifically represented as Al x Ga 1-x (In)As y P 1-yLayer, which can be Al x Ga 1-x As y P 1-y Layers, or Al x Ga 1-x InAs y P 1-y Furthermore, along the direction away from the first type semiconductor layer 10, the As component y in the first gradient transition layer 20 gradually increases, and the P component (1-y) gradually decreases.

[0115] In this embodiment, the first gradient transition layer 20 is an AlGa(In)AsP layer. Specifically, the amount of As source (AsH3 source) and P source (PH3 source) provided can be controlled to achieve a gradual decrease in the P component and a gradual increase in the As component along the direction away from the first type semiconductor layer 10 in the first gradient transition layer 20.

[0116] When the first gradient transition layer 20 is Al x Ga 1-x As y P 1-y Specifically, during the growth process, the reaction chamber temperature is gradually increased to 650℃-780℃, and TMAl, TMGa, AsH3, and PH3 sources are introduced to form Al on the side of the first type semiconductor layer 10 facing away from the first substrate 110. x Ga 1-x As y P 1-y The layer serves as the first gradient transition layer 20, wherein the amount of PH3 source provided gradually decreases, causing the P component in the first gradient transition layer 20 to gradually decrease along the direction away from the first type semiconductor layer 10, while the amount of AsH3 source provided gradually increases, causing the As component in the first gradient transition layer 20 to gradually increase along the direction away from the first type semiconductor layer 10.

[0117] When the first gradient transition layer 20 is Al x Ga 1-x InAs y P 1-y Specifically, during the growth process, the reaction chamber temperature is gradually increased to 650℃-780℃, and TMAl, TMGa, TMIn, AsH3, and PH3 sources are introduced to form Al on the side of the first type semiconductor layer 10 facing away from the first substrate 110. x Ga 1-x InAs y P 1-yThe layer serves as the first graded transition layer 20. Among them, the supply amount of the PH3 source gradually decreases, such that along the direction away from the first-type semiconductor layer 10, the P component in the first graded transition layer 20 gradually decreases. At the same time, the supply amount of the AsH3 source gradually increases, such that along the direction away from the first-type semiconductor layer 10, the As component in the first graded transition layer 20 gradually increases.

[0118] In this embodiment, the first graded transition layer 20 can be an undoped AlGa(In)AsP layer. Optionally, the thickness of the first graded transition layer 20 ranges from 0.01 μm to 0.05 μm, but this application does not limit this, and it depends on the specific situation.

[0119] In this embodiment, the Al component in the first graded transition layer 20 ranges from 45% to 60%, including the end values.

[0120] S230: As shown in FIG. 7(e), a multi-quantum well active layer 30 is formed on the side of the first graded transition layer 20 away from the first-type semiconductor layer 10. The multi-quantum well active layer 30 includes alternately arranged potential well layers 31 and potential barrier layers 32. Both the potential well layers 31 and the potential barrier layers 32 are AlGaAs layers, and the Al component of the potential barrier layer 32 is greater than that of the potential well layer 31.

[0121] Specifically, the reaction chamber temperature is maintained at 650°C - 780°C, and TMAl source, TMGa source, and AsH3 source are introduced to alternately grow the potential well layer 31 (Al a Ga 1-a As layer) and the potential barrier layer 32 (Al b Ga 1-b As layer), where a and b satisfy: 0 < a < b < 1. This is because in the AlGaAs material, the larger the Al component, the larger its bandgap, and a < b makes the bandgap of the potential well layer 32 smaller than that of the potential barrier layer 31, so that electrons are confined in each potential well layer 31 and recombine with holes in each potential well layer 31 to emit light. And because both the potential well layer 31 and the potential barrier layer 32 in the multi-quantum well active layer are AlGaAs layers and the crystal growth materials are the same, the growth interfaces of the potential well layer 31 and the potential barrier layer 32 can be clearly switched, which is beneficial to improving the crystal growth quality of the multi-quantum well active layer, improving the light emission efficiency and production yield of the LED chip.

[0122] It should be noted that only one group of potential well layer 31 and potential barrier layer 32 is drawn in FIG. 7(e). In fact, there are multiple groups of potential well layer 31 and potential barrier layer 32 in the multi-quantum well active layer 30.

[0123] In the multi-quantum-well active layer 30, a potential well layer 31 and a potential barrier layer 32 adjacent to each other form a period. Optionally, the number of periods can be in the range of 5 to 15, including the endpoint value, that is, the logarithm of the potential well layer 31 and the potential barrier layer 32 is 5 to 15. However, this application does not limit this and it depends on the specific situation.

[0124] Optionally, in one embodiment of this application, the Al composition a of each potential well layer 31 in the multi-quantum well active layer 30 is greater than 0% and less than 45%; the Al composition b of each potential barrier layer 32 in the multi-quantum well active layer is greater than 45% and less than 60%.

[0125] Optionally, the total thickness of the multi-quantum-well active layer 30 can range from 0.5 μm to 1.5 μm, including the endpoint values, but this application does not limit it and it depends on the specific circumstances.

[0126] S240: As shown in Figure 7(f), a second type semiconductor layer 40 is formed on the side of the multi-quantum well active layer 30 away from the first type semiconductor layer 10.

[0127] Specifically, the reaction chamber temperature is maintained at 650℃-750℃, and TMAl, TMGa, TMIn, and PH3 sources are introduced. An AlGaInP layer is formed on the side of the multi-quantum-well active layer away from the first-type semiconductor layer as a second-type semiconductor layer, with a thickness of 0.2μm-0.5μm. A P-type doping source (which can be a Mg / C / Zn doping source) is incorporated, with a carrier concentration of 5E17 / cm³. 3 -2E18 / cm 3 .

[0128] In practical applications, after forming the second type semiconductor layer 40, the formation process of the stacked structure 100 typically includes:

[0129] S241: As shown in Figure 7(g), a transition layer 90 and a window layer 91 are sequentially formed on the side of the second type semiconductor layer 40 away from the multi-quantum well active layer 30.

[0130] The window layer 91 can be a GaP layer with a highly doped surface, which forms a good ohmic contact with the electrode corresponding to the second type semiconductor layer 40 and allows the current to spread uniformly within the GaP window layer 91, resulting in a more uniform luminous intensity of the LED chip and an increased luminous area of ​​the LED chip.

[0131] Specifically, the reaction chamber temperature is raised to 600℃-780℃ to grow a GaP window layer 91 with a thickness of 0.15μm-3μm, doped with P-type dopants such as Mg / C / Zn, with a carrier concentration of 1E18 / cm³. 3 -1E19 / cm3 .

[0132] S300: As shown in Figure 7(h), the stacked structure 100 is bonded to the second substrate 120 from the side of the stacked structure 100 away from the first substrate 110, and the first substrate 110 is removed to achieve substrate transfer.

[0133] The buffer layer 111 and the corrosion stop layer 112 originally grown on the first substrate 110 are removed during substrate transfer.

[0134] In practical applications, the method further includes: as shown in FIG7(i), forming a first electrode 130 on the side of the stacked structure 100 away from the second substrate 120, and forming a second electrode 140 on the side of the second substrate 120 away from the stacked structure 100, thereby forming an LED chip structure.

[0135] In this embodiment, because the growth temperatures of the AlGaInP layer and the AlGaAs layer are different, there is a problem of growth temperature transition when switching between the growth of the first type semiconductor layer 10 (AlGaInP layer) and the multi-quantum well active layer 30 (AlGaAs layer). This complicates the fabrication process of the multi-quantum well active layer, making it prone to growth stalls or temperature changes during growth, resulting in poor crystal growth quality of the multi-quantum well active layer. In the LED chip fabrication method provided in this application embodiment, the first type semiconductor layer 10 (AlGaInP layer) and the multi-quantum well active layer 30 (AlGaAs layer) are... A first gradient transition layer 20 is added between the two layers. The first gradient transition layer 20 is an AlGa(In)AsP layer, which serves as a gradient transition layer for the growth temperature. The first gradient transition layer can be grown at varying temperatures. Its growth temperature can gradually change from the low temperature of growing AlGaInP layer to the high temperature of growing AlGaAs, reducing the instability caused by the temperature switching between the first type semiconductor layer 10 and the multi-quantum well active layer 30. It plays a protective role in the growth of the multi-quantum well active layer, thereby improving the crystal growth quality of the multi-quantum well active layer, reducing non-radiative recombination inside the multi-quantum well active layer, and improving the luminous efficiency and yield of the LED chip.

[0136] Furthermore, when the multi-quantum well active layer 30 (AlGaAs layer) is directly grown on the first type semiconductor layer 10 (AlGaInP layer), the aforementioned problems of unclear AlGaInP and AlGaAs layer switching interfaces, the appearance of derivatives at the interface, and the tendency to generate strain and dislocations that cause epitaxial wafer warping, all affect the crystal growth quality of the multi-quantum well active layer. Therefore, in the LED chip fabrication method provided in this application embodiment, a first gradient transition layer 20 is added between the first type semiconductor layer 10 (AlGaInP layer) and the multi-quantum well active layer 30 (AlGaAs layer), and the first gradient transition layer 20 is an AlGa(In)AsP layer, thereby effectively reducing the stress and defects introduced by the As / P switching. This reduces the generation of derivatives, making the switching interface between the AlGaAs layer and the AlGaInP layer clearer. In the direction from the first type semiconductor layer 10 to the multi-quantum well active layer 30, the P component in the first gradient transition layer 20 gradually decreases and the As component gradually increases. That is, through the gradual change of the P and As components in the first gradient transition layer 20, the first gradient transition layer 20 gets closer to the multi-quantum well active layer 30 and the more it matches the material of the multi-quantum well active layer 30. This makes the lattice matching between the first type semiconductor layer 10 and the multi-quantum well active layer 30 more consistent, suppresses the generation of dislocations, further improves the crystal growth quality of the multi-quantum well active layer, reduces non-radiative recombination inside the multi-quantum well active layer, and improves the luminous efficiency and yield of the LED chip.

[0137] Furthermore, in the LED chip fabrication method provided in this application embodiment, the first gradient transition layer 20 added between the first type semiconductor layer 10 (AlGaInP layer) and the multi-quantum well active layer 30 (AlGaAs layer) is an AlGa(In)AsP layer. Since the band gap of the AlGa(In)AsP layer is greater than that of the AlGaAs layer, the first gradient transition layer 20 is also equivalent to a barrier layer with a band gap larger than that of the barrier layer 32 in the multi-quantum well active layer 30. This can prevent electrons from overflowing from the multi-quantum well active layer 30, improve the recombination of electrons and holes in the multi-quantum well active layer, and further improve the luminous efficiency of the LED chip.

[0138] Therefore, in the LED chip fabrication method provided in this application embodiment, by adding a first gradient transition layer 20 (AlGa(In)AsP layer) between the first type semiconductor layer 10 (AlGaInP layer) and the multi-quantum well active layer 30 (AlGaAs layer), the influence of growth temperature conversion and material matching on the growth quality of the multi-quantum well active layer 30 can be eliminated, making the growth process of the multi-quantum well active layer 30 simpler, improving the crystal quality of the multi-quantum well active layer 30 and subsequent epitaxial layers, and improving the luminous efficiency and yield of the LED chip.

[0139] It should be noted that, as mentioned above, when directly growing an AlGaAs layer on an AlGaInP layer, due to the segregation of In at high temperatures, rapid temperature switching may cause the formation of InGaAlAs(P) derivatives at the interface. However, the elemental composition of these derivatives is disordered, and their positions are uncontrollable. Therefore, these InGaAlAs(P) derivatives not only do not benefit the material matching and growth temperature matching between the first type semiconductor layer 10 (AlGaInP layer) and the multi-quantum-well active layer 30 (AlGaAs layer), but also exacerbate the mismatch between materials and growth temperature. In the LED chip fabrication method provided in the embodiments of this application, in the first type semiconductor layer 10 (AlGaInP layer), the growth temperature is not controlled. Between the GaInP layer and the multi-quantum-well active layer 30 (AlGaAs layer), a first gradient transition layer (AlGa(In)AsP layer) with gradually changing As and P compositions is added. The first gradient transition layer can be grown at varying temperatures, gradually changing from the low temperature of growing the AlGaInP layer to the high temperature of growing AlGaAs. This prevents the loss of In composition, makes the growth interface clear, and serves as a temperature gradient transition layer. On the other hand, it makes the material lattice matched, reduces stress and defects, and reduces the generation of derivatives. This improves the crystal growth quality of the quantum well active layer, reduces non-radiative recombination inside the multi-quantum-well active layer, and improves the luminous efficiency and yield of the LED chip.

[0140] In this embodiment, the first semiconductor layer 10 can be an N-type semiconductor layer and the second semiconductor layer 20 can be a P-type semiconductor layer, but this application does not limit this and it depends on the specific situation.

[0141] Based on the above embodiments, in one embodiment of this application, along the direction from the first type semiconductor layer 10 to the multi-quantum well active layer 30, the P component in the first gradient transition layer 20 gradually decreases to 0%, and the As component gradually increases to 100%, that is, the side of the first gradient transition layer 20 (AlGa(In)AsP layer) closer to the multi-quantum well active layer 30 (AlGaAs layer) is more matched with the multi-quantum well active layer 30 (AlGaAs layer).

[0142] Optionally, in one embodiment of this application, the growth temperature of the first type semiconductor layer 10 is a first temperature T1, and the growth temperature of the multi-quantum well active layer 30 is a second temperature T2. In this method, when the first type semiconductor layer 10 forms a first gradient transition layer 20 on the side away from the first substrate 110, the growth temperature of the first gradient transition layer 20 gradually transitions from the first temperature T1 to the second temperature T2, and the second temperature T2 is greater than the first temperature T1. This allows the growth temperature to gradually transition from the growth temperature of the first type semiconductor layer 10 to the growth temperature of the multi-quantum well active layer 30 by adding the first gradient transition layer 20 between the first type semiconductor layer 10 and the multi-quantum well active layer 30, thereby further improving the crystal growth quality of the multi-quantum well active layer 30.

[0143] Optionally, the first temperature T1 can be in the range of 650℃-750℃, including the endpoint values;

[0144] Optionally, the second temperature T2 can be in the range of 650℃-780℃, including the endpoint values.

[0145] As mentioned above, the first type semiconductor layer 10 is an AlGaInP layer, and its growth temperature should not be too high to prevent the re-evaporation of In. The multi-quantum well active layer 30 is an AlGaAs layer, and its growth temperature needs to be higher to ensure the migration ability of Al atoms. In addition, the higher temperature can reduce the incorporation of background doping in the AlGaAs layer. Therefore, in this embodiment, the second temperature T2 is greater than the first temperature T1.

[0146] To further improve the brightness and luminous efficiency of the LED chip, the second semiconductor layer 40 also needs to be made of a material that absorbs less light emitted from the multi-quantum-well active layer. Considering that the AlGaInP layer absorbs less near-infrared light, it is optional that, in one embodiment of this application, the second semiconductor layer 40 is also made of AlGaInP. However, since the growth temperatures of the AlGaInP layer and the AlGaAs layer are different, there will be a problem of growth temperature transition when switching between the growth of the multi-quantum-well active layer 30 (AlGaAs layer) and the second semiconductor layer 40 (AlGaInP layer). This makes the process of the multi-quantum-well active layer more complex and prone to growth stalls or temperature changes during growth, resulting in poor crystal growth quality of the multi-quantum-well active layer. Based on this, in this embodiment, if... Figure 8 As shown, when forming the stacked structure 100, specifically before forming the second type semiconductor layer 40, the method further includes:

[0147] S250: Reference Figure 3As shown, a second gradient transition layer 50 is formed on the side of the multi-quantum well active layer 30 away from the first type semiconductor layer 10. The second gradient transition layer 50 is an AlGa(In)AsP layer, and along the direction toward the multi-quantum well active layer 30, the P component in the second gradient transition layer 50 gradually decreases and the As component gradually increases.

[0148] In this embodiment, a second gradient transition layer 50 is added between the multi-quantum well active layer 30 (AlGaAs layer) and the second type semiconductor layer 40 (AlGaInP layer). The second gradient transition layer 50 is an AlGa(In)AsP layer, which also serves as a growth temperature gradient transition layer. The second gradient transition layer can be grown at varying temperatures, with its growth temperature gradually changing from the high temperature for growing AlGaAs to the low temperature for growing AlGaInP. This reduces the instability caused by the temperature switching between the multi-quantum well active layer 30 and the second type semiconductor layer 40, protecting the growth of the multi-quantum well active layer. This improves the crystal growth quality of the multi-quantum well active layer, reduces non-radiative recombination within the multi-quantum well active layer, and improves the luminous efficiency and yield of the LED chip.

[0149] In this embodiment, the second gradient transition layer 50 is an AlGa(In)AsP layer, specifically represented as Al m Ga 1-m (In)As n P 1-n Layer, which can be Al m Ga 1-m As n P 1-n Layers, or Al m Ga 1-m InAs n P 1-n Furthermore, along the direction toward the multi-quantum-well active layer 30 (AlGaAs layer), the As component n in the second gradient transition layer 50 gradually increases, and the P component (1-n) gradually decreases. That is, along the direction away from the multi-quantum-well active layer 30 (AlGaAs layer), the As component n in the second gradient transition layer 50 gradually decreases, and the P component (1-n) gradually increases. In other words, through the gradual change of the P component and the As component in the second gradient transition layer 20, the second gradient transition layer 50 gets closer to the multi-quantum-well active layer 30 and is more matched with the material of the multi-quantum-well active layer 30. This makes the lattice matching between the second type semiconductor layer 40 and the multi-quantum-well active layer 30 more favorable for the crystal growth quality of the multi-quantum-well active layer and the second type semiconductor layer.

[0150] In this embodiment, the second gradient transition layer 20 is an AlGa(In)AsP layer. Specifically, the amount of As source (AsH3 source) and P source (PH3 source) provided can be controlled to achieve a gradual increase in the P component and a gradual decrease in the As component along the direction away from the multi-quantum well active layer 30 in the second gradient transition layer 20.

[0151] When the second gradient transition layer 50 is Al m Ga 1-m As n P 1-n Specifically, during the layering process, the reaction chamber temperature is gradually reduced to 650℃-750℃, and TMAl, TMGa, AsH3, and PH3 sources are introduced to form Al on the side of the multi-quantum-well active layer 30 away from the first-type semiconductor layer 10. m Ga 1-m As n P 1-n The layer serves as the second gradient transition layer 50, in which the amount of PH3 source provided gradually increases, causing the P component in the second gradient transition layer 50 to gradually increase along the direction away from the multi-quantum well active layer 30. At the same time, the amount of AsH3 source provided gradually decreases, causing the As component in the second gradient transition layer 50 to gradually decrease along the direction away from the multi-quantum well active layer 30.

[0152] When the second gradient transition layer 50 is Al m Ga 1-m InAs n P 1-n Specifically, during the layering process, the reaction chamber temperature is gradually reduced to 650℃-750℃, and TMAl, TMGa, TMIn, AsH3, and PH3 sources are introduced to form Al on the side of the multi-quantum-well active layer 30 away from the first-type semiconductor layer 10. m Ga 1-m InAs n P 1-n The layer serves as the second gradient transition layer, in which the amount of PH3 source provided gradually increases, causing the P component in the second gradient transition layer 50 to gradually increase along the direction away from the multi-quantum-well active layer 30. At the same time, the amount of AsH3 source provided gradually decreases, causing the As component in the second gradient transition layer 50 to gradually decrease along the direction away from the multi-quantum-well active layer 30.

[0153] In this embodiment, the second gradient transition layer 50 can be an undoped AlGa(In)AsP layer. Optionally, the thickness of the second gradient transition layer 50 can range from 0.01 μm to 0.05 μm, but this application does not limit it and it depends on the specific situation.

[0154] In this embodiment, the Al component in the second gradient transition layer 50 ranges from 45% to 60%, including the endpoint values.

[0155] In this embodiment, reference Figure 3 As shown, forming a second type semiconductor layer on the side of the multi-quantum-well active layer 30 opposite to the first type semiconductor layer 10 includes:

[0156] A second type semiconductor layer 40 is formed on the side of the second gradient transition layer 40 that is away from the multi-quantum well active layer 30.

[0157] In this embodiment, gradient transition layers are provided on both sides of the multi-quantum-well active layer 30 (AlGaAs layer). These layers act as a gradient transition layer between the AlGaAs layer and the AlGaInP layer, serving as a growth temperature gradient transition layer. Furthermore, in both gradient transition layers, the P composition gradually decreases and the As composition gradually increases as they approach the multi-quantum-well active layer 30 (AlGaAs layer). This makes the switching interface between the AlGaAs layer and the AlGaInP layer clearer, the lattice more matched, reduces stress and defects, reduces the generation of derivatives, further improves the crystal growth quality of the multi-quantum-well active layer, reduces non-radiative recombination within the multi-quantum-well active layer, and improves the luminous efficiency and yield of the LED chip.

[0158] Based on the above embodiments, in one embodiment of this application, along the direction from the second type semiconductor layer 40 to the multi-quantum well active layer 30, the P component in the second gradient transition layer 50 gradually decreases to 0%, and the As component gradually increases to 100%, that is, the side of the second gradient transition layer 50 (AlGa(In)AsP layer) closer to the multi-quantum well active layer 30 (AlGaAs layer) is more matched with the multi-quantum well active layer (AlGaAs layer).

[0159] Optionally, in one embodiment of this application, the growth temperature of the multi-quantum well active layer 30 is a second temperature T2, and the growth temperature of the second type semiconductor layer 40 is a third temperature T3. When the second gradient transition layer 50 is formed on the side of the multi-quantum well active layer 30 away from the first type semiconductor layer 10, the growth temperature of the second gradient transition layer 50 gradually transitions from the second temperature T2 to the third temperature T3, and the third temperature T3 is lower than the second temperature T2. This allows the growth temperature to gradually transition from the growth temperature of the first type semiconductor layer 10 to the growth temperature of the multi-quantum well active layer 30 by adding a first gradient transition layer 20 between the first type semiconductor layer 10 and the multi-quantum well active layer 30, thereby further improving the crystal growth quality of the multi-quantum well active layer 30.

[0160] Optionally, the second temperature T2 can be in the range of 650℃-780℃, including the endpoint values;

[0161] Optionally, the third temperature T3 can be in the range of 650℃-750℃, including the endpoint values.

[0162] As mentioned above, the second type semiconductor layer 40 is an AlGaInP layer, and its growth temperature should not be too high to prevent the re-evaporation of In. The multi-quantum well active layer 30 is an AlGaAs layer, and its growth temperature needs to be higher to ensure the migration ability of Al atoms. In addition, the higher temperature can reduce the incorporation of background doping in the AlGaAs layer. Therefore, in this embodiment, the third temperature T3 is lower than the second temperature T2.

[0163] In summary, the LED chip provided in this application embodiment adds a first gradient transition layer between the first type semiconductor layer (AlGaInP layer) and the multi-quantum well active layer (AlGaAs layer). The first gradient transition layer is an AlGa(In)AsP layer, which serves as a growth temperature gradient transition layer and effectively reduces the generation of defects and derivatives. This makes the switching interface between the AlGaAs layer and the AlGaInP layer clear. Furthermore, along the direction from the first type semiconductor layer to the multi-quantum well active layer, the P component in the first gradient transition layer gradually decreases, while the As component gradually increases. In other words, the gradient of the P and As components in the first gradient transition layer enables lattice matching between the first type semiconductor layer and the multi-quantum well active layer, improves the crystal growth quality of the multi-quantum well active layer, reduces non-radiative recombination inside the multi-quantum well active layer, and improves the luminous efficiency and yield of the LED chip. In addition, the first gradient transition layer is also equivalent to a barrier layer with a larger bandgap than the barrier layer in the multi-quantum well active layer. This can prevent electrons from escaping from the multi-quantum well active layer, improve the recombination of electrons and holes inside the multi-quantum well active layer, and further improve the luminous efficiency of the LED chip.

[0164] The various parts of this manual are described in a combination of parallel and progressive methods. Each part focuses on the differences between the other parts, and the same or similar parts can be referred to each other.

[0165] The features described above regarding the disclosed embodiments can be substituted or combined with each other to enable those skilled in the art to implement or use this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. An LED chip, characterized in that, The stacked structure includes: a first type semiconductor layer, a first gradient transition layer, a multi-quantum well active layer, and a second type semiconductor layer stacked sequentially. The first type of semiconductor layer is an AlGaInP layer; The multi-quantum-well active layer includes alternating potential well layers and potential barrier layers, both of which are AlGaAs layers, and the Al composition of the barrier layer is greater than that of the potential well layer. The first gradient transition layer is an AlGaAsP layer or an AlGaInAsP layer, and along the direction from the first type of semiconductor layer to the multi-quantum well active layer, the P component in the first gradient transition layer gradually decreases and the As component gradually increases. Wherein, the growth temperature of the first type semiconductor layer is the first temperature, the growth temperature of the multi-quantum well active layer is the second temperature, and when the first gradient transition layer is formed on the first type semiconductor layer, the growth temperature of the first gradient transition layer gradually transitions from the first temperature to the second temperature, and the second temperature is greater than the first temperature.

2. The LED chip according to claim 1, characterized in that, Along the direction from the first type of semiconductor layer to the multi-quantum-well active layer, the P component in the first gradient transition layer gradually decreases to 0%, and the As component gradually increases to 100%.

3. The LED chip according to claim 1, characterized in that, The second type semiconductor layer is an AlGaInP layer. The stacked structure further includes a second gradient transition layer located between the multi-quantum well active layer and the second type semiconductor layer. The second gradient transition layer is an AlGaAsP layer or an AlGaInAsP layer, and is located along the direction from the second type semiconductor layer to the multi-quantum well active layer. In the second gradient transition layer, the P component gradually decreases and the As component gradually increases.

4. The LED chip according to claim 3, characterized in that, Along the direction from the second type semiconductor layer to the multi-quantum-well active layer, the P component in the second gradient transition layer gradually decreases to 0%, and the As component gradually increases to 100%.

5. The LED chip according to claim 3, characterized in that, The Al component in the first gradient transition layer ranges from 45% to 60%, including the endpoint values; The Al component in the second gradient transition layer ranges from 45% to 60%, including the endpoint values.

6. The LED chip according to claim 1, characterized in that, The Al composition of each potential well layer in the multi-quantum well active layer is greater than 0% and less than 45%. The Al composition of each barrier layer in the multi-quantum well active layer is greater than 45% and less than 60%.

7. A method for fabricating an LED chip, characterized in that, include: Provide a first substrate; A stacked structure is formed on one side of the first substrate, the formation process of the stacked structure including: A first type semiconductor layer is formed on one side of the first substrate, wherein the first type semiconductor layer is an AlGaInP layer; A first gradient transition layer is formed on the side of the first type semiconductor layer away from the first substrate. The first gradient transition layer is an AlGaAsP layer or an AlGaInAsP layer. Along the direction away from the first type semiconductor layer, the P component in the first gradient transition layer gradually decreases and the As component gradually increases. A multi-quantum-well active layer is formed on the side of the first gradient transition layer away from the first type of semiconductor layer. The multi-quantum-well active layer includes alternating potential well layers and potential barrier layers. Both the potential well layers and the potential barrier layers are AlGaAs layers, and the Al composition of the potential barrier layer is greater than that of the potential well layer. A second type semiconductor layer is formed on the side of the multi-quantum-well active layer that is away from the first type semiconductor layer; From the side of the stacked structure opposite to the first substrate, the stacked structure is bonded to the second substrate, and the first substrate is removed to achieve substrate transfer; Wherein, the growth temperature of the first type of semiconductor layer is the first temperature, and the growth temperature of the multi-quantum well active layer is the second temperature. When the first type of semiconductor layer forms a first gradient transition layer on the side away from the first substrate, the growth temperature of the first gradient transition layer gradually transitions from the first temperature to the second temperature, and the second temperature is greater than the first temperature.

8. The method for preparing an LED chip according to claim 7, characterized in that, The second type of semiconductor layer is an AlGaInP layer. Specifically, before forming the second type of semiconductor layer, the method further includes the following steps when forming the stacked structure: A second gradient transition layer is formed on the side of the multi-quantum well active layer away from the first type of semiconductor layer. The second gradient transition layer is an AlGaAsP layer or an AlGaInAsP layer. Along the direction toward the multi-quantum well active layer, the P component in the second gradient transition layer gradually decreases and the As component gradually increases. Forming a second type semiconductor layer on the side of the multi-quantum-well active layer opposite to the first type semiconductor layer includes: A second type semiconductor layer is formed on the side of the second gradient transition layer that is away from the multi-quantum-well active layer.

9. The method for preparing an LED chip according to claim 8, characterized in that, The growth temperature of the multi-quantum well active layer is a second temperature, and the growth temperature of the second type semiconductor layer is a third temperature. In this method, when a second gradient transition layer is formed on the side of the multi-quantum well active layer away from the first type semiconductor layer, the growth temperature of the second gradient transition layer gradually transitions from the second temperature to the third temperature, and the third temperature is lower than the second temperature.

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