Micro-led transverse polarization field regulating structure and preparation method thereof

Abstract

This invention discloses a MicroLED lateral polarization field modulation structure and its fabrication method, belonging to the field of semiconductor optoelectronic device technology. It solves the problem of carrier drift caused by lateral polarization field imbalance due to stress imbalance on the sidewalls of existing MicroLEDs. The technical solution includes a MicroLED epitaxial structure disposed on a CMOS backplane. The MicroLED epitaxial structure includes a p-type semiconductor layer, a multi-quantum-well emitting layer, and an n-type semiconductor layer sequentially disposed. A polarization field modulation structure with preset internal stress is disposed on the sidewall of the MicroLED epitaxial structure corresponding to the multi-quantum-well emitting layer. This invention introduces a polarization field modulation structure into the multi-quantum-well region of the MicroLED sidewall, redistributing the stress near the multi-quantum-well, thereby reducing the lateral polarization field gradient, suppressing carrier drift to the sidewall, and improving luminous efficiency and device consistency.

Description

Technical Field

[0001] This invention belongs to the field of semiconductor optoelectronic device technology, specifically relating to a lateral polarization field modulation structure for MicroLED (Micro Light Emitting Diode Display). This invention also relates to a method for fabricating the MicroLED lateral polarization field modulation structure. Background Technology

[0002] As MicroLED display technology continues to develop towards ultra-high resolution, high brightness, and small size, pixel size has gradually shrunk from tens of micrometers to below 10μm, and even into the range of below 5μm. For AR (Augmented Reality) near-eye displays, in order to achieve an ultra-high pixel density of over 3000 PPI (pixels per inch), the size of MicroLED devices has been further reduced, significantly increasing the proportion of the sidewall area in the entire light-emitting area.

[0003] GaN-based MicroLEDs typically employ InGaN / GaN multiple quantum wells as the light-emitting layer. Because GaN material has a wurtzite crystal structure, strong piezoelectric and spontaneous polarization naturally exist within the multiple quantum wells due to lattice and thermal mismatches. When the device size is large, this polarization field mainly manifests as a vertical polarization field along the epitaxial growth direction, with a relatively limited impact on device performance. However, as MicroLED sizes continue to shrink, the new sidewalls formed by Mesa etching disrupt the original stress balance. Significant stress release and strain redistribution occur in the multiple quantum well regions near the sidewalls, forming a horizontally varying polarization gradient and further generating a transverse polarization electric field. This transverse polarization field drives electrons and holes to migrate towards the sidewalls, shifting the carrier distribution and increasing the probability of nonradiative recombination near the sidewalls, leading to a decrease in luminous efficiency. Simultaneously, the varying magnitudes of the transverse polarization field at different locations also cause wavelength drift, brightness inhomogeneity, and increased performance dispersion between different pixels. This problem becomes more prominent when the size of MicroLEDs is further reduced to below 5μm, becoming one of the important factors limiting the high efficiency of MicroLEDs.

[0004] Currently, existing technologies mainly reduce sidewall defect density through methods such as sidewall passivation layers, wet repair, plasma treatment, and atomic layer deposition (ALD). While these methods can reduce some surface states and defect recombination, they primarily target chemical defect repair and do not alter the stress and polarization field distribution within the multiple quantum wells. Therefore, they cannot fundamentally solve the carrier migration problem caused by the transverse polarization field. Thus, there is an urgent need for a novel MicroLED structure capable of actively controlling the strain distribution of the sidewall multiple quantum wells and reducing the intensity of the transverse polarization field to improve the luminous efficiency and luminous uniformity of small-sized MicroLEDs. Summary of the Invention

[0005] The purpose of this invention is to provide a transverse polarization field control structure for MicroLEDs, which solves the problem of carrier drift caused by transverse polarization field due to stress imbalance on the sidewalls of existing MicroLEDs.

[0006] Another objective of this invention is to provide a method for preparing a MicroLED lateral polarization field modulation structure.

[0007] The first technical solution adopted in this invention is: a MicroLED lateral polarization field control structure, including a MicroLED epitaxial structure disposed on a CMOS (Complementary Metal Oxide Semiconductor) backplane. The MicroLED epitaxial structure includes a p-type semiconductor layer, a multi-quantum well light-emitting layer and an n-type semiconductor layer disposed sequentially. The sidewall of the MicroLED epitaxial structure is provided with a polarization field control structure having a preset internal stress corresponding to the multi-quantum well light-emitting layer.

[0008] The first technical solution of this invention is further characterized by: The material for the polarization field modulation structure is selected from SiN x , Al2O3, SiO2, AlN, AlON or AlGaN.

[0009] The thickness of the polarization field-controlled structure is 20–300 nm.

[0010] The internal stress range of the polarization field-controlled structure is -1 to +1 GPa.

[0011] The polarization field modulation structure only covers the sidewalls at the corresponding height of the multi-quantum well light-emitting layer, or covers the sidewall regions within a range of 100–300 nm above and below the multi-quantum well light-emitting layer.

[0012] The polarization field controlled structure was prepared using PECVD (Plasma Enhanced Chemical Vapor Deposition), ALD, magnetron sputtering, or low-pressure chemical vapor deposition processes.

[0013] A transparent conductive layer extending laterally to the top of the n-type semiconductor layer extends to the cathode electrode in the CMOS backplane. A metal filling structure that penetrates the insulating medium downwards and connects to the cathode electrode is connected to the bottom of the transparent conductive layer.

[0014] A microlens is provided on the top of the MicroLED epitaxial structure.

[0015] The multi-quantum-well light-emitting layer consists of 4 to 8 pairs of InGaN / GaN quantum wells, with a thickness of 2 to 4 nm for each quantum well and a barrier layer thickness of 8 to 12 nm.

[0016] The second technical solution adopted in this invention is: a method for preparing a MicroLED lateral polarization field modulation structure, comprising the following steps: Step 1: Sequentially grow an n-type semiconductor layer, a multi-quantum-well light-emitting layer, and a p-type semiconductor layer on the substrate; Step 2: Perform metal bonding between the MicroLED pixel layer and the CMOS backplane; Step 3: Define MicroLED pixels by photolithography and etch to form Mesa structure. The etching depth penetrates the p-type semiconductor layer and the multi-quantum-well light-emitting layer and enters the n-type semiconductor layer. Step 4: In the region of the Mesa structure corresponding to the multi-quantum-well light-emitting layer on the sidewall, a polarization field control structure is formed by depositing a dielectric material with preset internal stress.

[0017] The beneficial effects of the present invention are as follows: The MicroLED lateral polarization field control structure and its preparation method of the present invention introduce a polarization field control structure into the multi-quantum well region of the MicroLED sidewall, thereby redistributing the stress near the multi-quantum well, reducing the lateral polarization field gradient, suppressing carrier drift to the sidewall, and improving luminous efficiency and device consistency. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the MicroLED lateral polarization field modulation structure of the present invention; Figure 2 This is a schematic diagram illustrating the modulation principle of the MicroLED lateral polarization field modulation structure of the present invention; Figure 3 This is a schematic flowchart of the fabrication method of the MicroLED lateral polarization field modulation structure of the present invention.

[0019] In the diagram, 1. CMOS backplane, 2. MicroLED layer, 3. Microlens; 11. Anode electrode; 12. Cathode electrode; 21. Bonded metal, 22. p-type semiconductor layer, 23. Multiple quantum well light-emitting layer, 24. n-type semiconductor layer, 25. Polarization field modulation structure, 26. Metal-filled structure, 27. Transparent conductive layer. Detailed Implementation

[0020] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0021] Example 1 This invention provides a MicroLED lateral polarization field modulation structure, which utilizes strain engineering in the sidewall multi-quantum-well region to control the lateral polarization field distribution, reduce carrier lateral drift, and improve luminous efficiency and uniformity. It can be widely applied in AR near-eye displays, VR (Virtual Reality) displays, automotive displays, and high-PPI MicroLED display chips. Figure 1 As shown, it includes a CMOS backplane 1 and a MicroLED layer 2.

[0022] The CMOS backplane 1 includes an anode electrode 11 and a cathode electrode 12 for pixel driving, current injection, and electrical signal transmission. The anode electrode 11 is preferably made of Al, Cu, or Cu / Ti composite metal, and the cathode electrode 12 is preferably made of Al, Cu, Ti, or TiN structure, with a thickness of 0.5–3 μm.

[0023] MicroLED layer 2 is connected to the CMOS backplane via bonding metal 21. The bonding metal preferably uses Au, AuSn, Cu, CuSn, or a Cu-Cu mixed bonding structure, with a thickness preferably of 0.5–5 μm to ensure low contact resistance and high bonding reliability. The MicroLED epitaxial structure sequentially includes a p-type semiconductor layer 22, a multi-quantum-well light-emitting layer 23, and an n-type semiconductor layer 24. The p-type semiconductor layer 22 is connected to the anode electrode 11 of the CMOS backplane via bonding metal 21. The p-type semiconductor layer 22 is preferably Mg-doped GaN, with a thickness preferably of 100–300 nm. The multi-quantum-well light-emitting layer 23 is preferably composed of 4–8 pairs of InGaN / GaN quantum wells, with a single quantum well thickness preferably of 2–4 nm and a barrier layer thickness preferably of 8–12 nm. The n-type semiconductor layer 24 is preferably Si-doped GaN, with a thickness preferably of 2–5 μm.

[0024] After etching the MicroLED layer 2Mesa, a polarization field control structure 25 is formed in the multi-quantum well region corresponding to the sidewall of the MicroLED epitaxial structure. This structure does not participate in the device conduction. Its main function is to provide a preset mechanical stress in the sidewall region of the multi-quantum well. By changing the strain distribution near the sidewall, the piezoelectric polarization gradient is controlled, and the transverse polarization field intensity is reduced.

[0025] The polarization field modulation structure 25 can be made of SiN x It is formed from a dielectric material such as Al2O3, SiO2, AlN, AlGaN, or other materials with preset internal stress, and its lateral thickness is preferably 20-300 nm, more preferably 50-150 nm. By adjusting the deposition process parameters, the structure is made to have compressive or tensile stress, and its internal stress range is preferably controlled between -1 and +1 GPa, thereby changing the strain state of the multi-quantum well region near the sidewall.

[0026] The polarization field modulation structure 25 only covers the corresponding height of the multi-quantum well region, or covers the range of 100-300 nm above and below the quantum well, rather than completely covering the entire Mesa sidewall. This allows the strain modulation to mainly act on the light-emitting region, reducing the impact on the current injection path.

[0027] To achieve electrical connection between MicroLED layer 2 and CMOS backplane 1, a metal filling structure 26 is provided on the sidewall of the device. The metal filling structure is preferably located outside the Mesa and penetrates the dielectric layer, with its upper and lower ends connected to the transparent conductive layer 27 and the cathode electrode 12 of the CMOS backplane, respectively, forming a current transmission channel. The metal filling structure is preferably formed using Cu, W, Al, Ti, Cu / W composite metals, or other low-resistance conductive materials. Its main function is to achieve electrical connection, reduce series resistance, and improve driving reliability, without participating in polarization field modulation.

[0028] Example 2 A transparent conductive layer 27 is formed on top of the n-type semiconductor layer 24. The material is selected from ITO, and its thickness is preferably 80-150 nm, with a sheet resistance preferably of 20-80 Ω / sq. The transparent conductive layer 27 is used to improve current spread and enhance the current uniformity of the entire light-emitting area. In synergy with the microlens, it further improves the overall optoelectronic performance of the MicroLED.

[0029] Example 3 A microlens 3 is further formed on the top of the MicroLED epitaxial structure. The microlens can be made of photoresist, SiO2, polymer or glass material, and the radius of curvature is preferably 2 to 20 μm. It is used to improve the light extraction efficiency and improve the emission angle distribution. The synergistic optimization with the transparent conductive layer further improves the overall optoelectronic performance of the MicroLED.

[0030] Example 4 The core of this invention lies in altering the strain distribution near the sidewalls by controlling the structure through a polarization field. For GaN materials, the piezoelectric polarization satisfies:

[0031] in, and They represent the piezoelectric coefficients, , and These represent strain in three directions.

[0032] After the Mesa sidewalls are formed, the strain changes laterally, therefore:

[0033] in, This indicates the spatial coordinates along the MicroLED's transverse direction, pointing from the pixel center towards the Mesa sidewall.

[0034] Correspondingly, transverse bound charges are formed:

[0035] Further, a transverse electric field is formed:

[0036] in, It represents the dielectric constant, used to describe a material's ability to respond to an electric field.

[0037] Electron drift current satisfies:

[0038] in, Represents the elementary charge. Indicates carrier concentration. This represents the carrier mobility.

[0039] The polarization field control structure 25 employs a dielectric thin film with a preset internal stress, which can be compressive or tensile. After the dielectric thin film is deposited on the Mesa sidewall, the preset internal stress is transferred to the sidewall region through interfacial bonding. A controllable stress field is actively introduced into the Mesa sidewall, readjusting the strain distribution in the multi-quantum-well region near the sidewall, thus re-anchoring the lattice stress on the sidewall surface released by Mesa etching. The polarization field control structure 25 can be selected from SiN with adjustable internal stress. x A dielectric thin film was formed and deposited on the sidewall of Mesa corresponding to the multi-quantum-well light-emitting layer 23 using plasma-enhanced chemical vapor deposition. During the deposition process, the RF power, deposition pressure, substrate temperature, and SiH4 to NH3 flow ratio were adjusted to make SiN x The thin film forms a preset compressive or tensile stress.

[0040] Therefore, as Figure 2 As shown, when the strain gradient near the sidewall is large, the polarization gradient increases, the transverse polarization field is stronger, and electrons drift more easily towards the sidewall. This invention re-establishes the sidewall stress balance through polarization field modulation structure 25, pulling the previously significantly retreating sidewall surface lattice back to a strain state approximately similar to the internal bulk lattice. This significantly reduces the transverse strain gradient between the sidewall and the bulk region, making... The reduction is significant because the piezoelectric polarization effect is directly dependent on the strain distribution. The reduction of the strain gradient is equivalent to suppressing the accumulation of transverse bound charge, thereby reducing the transverse polarization field strength, reducing the transverse migration of charge carriers, and improving the degree of charge carrier localization inside the quantum well.

[0041] Simulation results show that when the sidewall strain gradient is reduced by 30%, the transverse polarization electric field can be reduced by about 40%, the transverse drift distance of charge carriers can be reduced by about 35%, the nonradiative recombination rate of the sidewall can be reduced by about 30%, and the external quantum efficiency of the device can be improved by about 15% to 25%.

[0042] Through the above-described method, this invention, for the first time, actively regulates the lateral polarization field of the MicroLED sidewalls from the perspective of multi-quantum-well strain control, rather than relying solely on traditional sidewall passivation to repair defects. Therefore, it can reduce carrier lateral drift from a physical mechanism perspective. The polarization field control structure applies a preset mechanical stress to the multi-quantum-well region of the Mesa sidewalls, re-establishing sidewall strain equilibrium, effectively reducing the lateral piezoelectric polarization gradient, and increasing the localization of carriers in the quantum wells. This reduces sidewall non-radiative recombination, decreases carrier lateral drift, and improves luminous efficiency and uniformity. Furthermore, this invention does not require changes to the existing MicroLED epitaxial structure; it only adds a local strain control structure to the sidewalls to achieve lateral polarization field optimization, is compatible with existing MicroLED processes, and has high industrial application value.

[0043] Example 5 This invention provides a method for fabricating a MicroLED lateral polarization field modulation structure, such as... Figure 3 As shown, it includes the following steps: Step 1: Sequentially grow an n-type semiconductor layer, a multi-quantum-well light-emitting layer, and a p-type semiconductor layer on the substrate; Step 2: Connect the MicroLED epitaxial layer to the CMOS backplane using metal bonding. Step 3: Remove the growth substrate of the MicroLED epitaxial structure using a wet process; Step 4: Define the MicroLED pixel pattern using photolithography; Step 5: Form the Mesa structure by ICP etching, with the etching depth penetrating the p-type semiconductor layer and the multi-quantum-well light-emitting layer and entering the n-type semiconductor layer; Step 6: In the region of the Mesa structure corresponding to the multi-quantum-well light-emitting layer on the sidewall, a polarization field control structure is formed by depositing a dielectric material with preset internal stress. Step 7: Deposit insulating dielectric material and form through-holes for electrode connections through photolithography and etching processes; Step 8: Fill the opening with metal to form a metal electrode that communicates with the back plate; Step 9: Deposit a transparent electrode on top of the Mesa and connect it to the aforementioned metal electrode; Step 10: Form a microlens structure on the upper part of the above transparent electrode; Step 11: Complete the fabrication of MicroLED devices.

[0044] Example 6 This invention is based on a metal-bonded MicroLED device structure. The entire device includes a CMOS backplane 1, a MicroLED layer 2, and a microlens 3 disposed on the top of the device. The CMOS backplane 1 includes an anode electrode 11 and a cathode electrode 12 for display driving, current injection, and display control. The MicroLED layer 2 includes a bonding metal 21, a p-type semiconductor layer 22, a multi-quantum-well light-emitting layer 23, an n-type semiconductor layer 24, a polarization field modulation structure 25, a metal-filled structure 26, and a transparent conductive layer 27. The microlens 3 is disposed on the top of the device to improve light extraction efficiency and enhance angular light emission characteristics.

[0045] This embodiment employs a GaN blue or green MicroLED epitaxial structure, which can be grown on a sapphire, silicon, or SiC substrate using metal-organic chemical vapor deposition (MOCVD). First, an n-type semiconductor layer 24, a multi-quantum-well light-emitting layer 23, and a p-type semiconductor layer 22 are sequentially grown on the substrate. The n-type semiconductor layer 24 preferably has a thickness of 2–5 μm, and the Si doping concentration is preferably 1 × 10⁻⁶. 18 ~5×10 18 cm -3 The multi-quantum-well light-emitting layer 23 preferably consists of 4 to 8 pairs of InGaN / GaN quantum wells, with a single quantum well thickness preferably of 2 to 4 nm and a barrier layer thickness preferably of 8 to 12 nm; the p-type semiconductor layer 22 preferably has a thickness of 100 to 250 nm and a Mg doping concentration preferably of 5 × 10⁻⁶. 18 ~2×10 19 cm -3 .

[0046] Metal bonding is performed between the bonding metal 21 and the CMOS backplane 1. The bonding metal is preferably AuSn eutectic bonding, Cu-Cu direct bonding, Cu / Sn mixed bonding or Au-Au hot-press bonding structure. The AuSn bonding temperature is preferably 280-320℃ and the Cu-Cu bonding pressure is preferably 5-30MPa.

[0047] After metal bonding is completed, the growth substrate is removed. MicroLED pixels are then defined using photolithography, and the Mesa structure is formed using ICP (inductively coupled plasma) etching. The etching preferably uses a Cl2 / BCl3 / Ar mixed gas, with an ICP power of 300–600 W and a bias voltage of 100–250 V. The etching depth penetrates the p-type semiconductor layer 22 and the multi-quantum-well light-emitting layer 23, reaching approximately 0.2–0.8 μm into the n-type semiconductor layer 24 to achieve electrical isolation between pixels. The Mesa sidewall tilt angle is preferably 70°–90°, and the pixel size is preferably 2–20 μm.

[0048] Due to the stress release caused by Mesa etching, a significant strain gradient forms near the multi-quantum-well light-emitting layer 23, leading to a redistribution of piezoelectric polarization and generating a transverse polarization field that varies along the horizontal direction. This invention incorporates a polarization field control structure 25 in the multi-quantum-well region of the Mesa sidewall, utilizing a dielectric layer with preset internal stress to re-establish local stress balance, thereby regulating the transverse polarization field.

[0049] The polarization field modulation structure 25 preferably adopts SiN x The dielectric layer is formed from materials such as Al2O3, SiO2, AlN, AlON, AlGaN, or other materials with compressive or tensile stress characteristics. The dielectric layer can be prepared using PECVD, ALD, magnetron sputtering, or low-pressure chemical vapor deposition processes, with PECVD depositing SiN... x This is the preferred embodiment. The deposition temperature is preferably 250–400℃, the deposition pressure is preferably 500–2000 mTorr, and the thickness is preferably 20–300 nm, more preferably 50–150 nm. By adjusting the PECVD RF power, the SiH4 / NH3 flow ratio, and the deposition pressure, compressive or tensile stress can be formed in the dielectric layer, and its internal stress range is preferably controlled between -1 and +1 GPa.

[0050] To concentrate strain modulation on the luminescent region, the present invention preferably makes the polarization field modulation structure 25 cover only the height corresponding to the multi-quantum-well luminescent layer 23, or cover the range of 100-300 nm above and below the quantum wells, rather than completely covering the entire Mesa sidewall. This can effectively regulate the stress state of the multi-quantum-wells without significantly affecting the current injection paths of the p-type and n-type semiconductor layers.

[0051] A metal-filled structure 26 is further formed outside the polarization field control structure 25. After the deposition of the polarization field control structure 25, the metal-filled structure 26 is formed outside the Mesa. The metal-filled structure penetrates the insulating medium and is connected to the top transparent conductive layer 27 and the cathode electrode 12, thereby forming a current transmission path on the n-side of the device. The metal filler is preferably made of Cu, W, Al, or other low-resistivity metal materials, and its thickness is preferably 0.5–5 μm. Since the metal-filled structure mainly performs the function of conduction, its position is located outside the polarization field control structure, and it does not directly affect the strain distribution in the multi-quantum-well region, nor does it participate in the transverse polarization field control.

[0052] Subsequently, a transparent conductive layer 27 is formed on top of the n-type semiconductor layer 24. ITO can be deposited by magnetron sputtering, with a thickness preferably of 80–150 nm, a sheet resistance preferably of 20–80 Ω / sq, and a transmittance preferably greater than 90%. The ITO layer can improve the lateral current spread, making the current distribution in the entire light-emitting area more uniform, and further reducing local current congestion.

[0053] Finally, a microlens 3 is formed on the top of the device. The microlens is preferably formed using a photoresist reflow process, an ultraviolet embossing process, or a glass molding process. Its radius of curvature is preferably 2–20 μm, and its height is preferably 1–10 μm, which can be optimized according to the pixel size. The microlens can improve the light emission direction, increase light extraction efficiency, and further reduce angular color shift.

[0054] Finite element simulation results show that when the polarization field modulates the internal stress of the structure to -500 MPa, the transverse strain gradient near the sidewall of the multi-quantum well can be reduced by about 35%, corresponding to a reduction of about 40% in the transverse polarization electric field, a reduction of about 30% in the transverse electron drift distance, and a reduction of about 25% in the nonradiative recombination rate in the sidewall region. Further combined optoelectronic simulations show that within the range of 10–100 A / cm... 2 Within the operating current density range, the external quantum efficiency of the device of this invention is improved by about 10% to 20% compared with the traditional structure, the light emission uniformity is improved by about 15%, and the peak wavelength drift is reduced by about 30%, effectively improving the consistency and long-term reliability of small-sized MicroLED devices.

Claims

1. A MicroLED lateral polarization field modulation structure, characterized in that, The MicroLED epitaxial structure is disposed on a CMOS backplane (1). The MicroLED epitaxial structure includes a p-type semiconductor layer (22), a multi-quantum well light-emitting layer (23) and an n-type semiconductor layer (24) disposed sequentially. The sidewall of the MicroLED epitaxial structure is provided with a polarization field control structure (25) with preset internal stress corresponding to the multi-quantum well light-emitting layer (23).

2. The MicroLED lateral polarization field modulation structure as described in claim 1, characterized in that, The material of the polarization field modulation structure (25) is selected from SiN. x , Al2O3, SiO2, AlN, AlON or AlGaN.

3. The MicroLED lateral polarization field modulation structure as described in claim 1, characterized in that, The thickness of the polarization field modulation structure (25) is 20-300 nm.

4. The MicroLED lateral polarization field modulation structure as described in claim 1, characterized in that, The internal stress range of the polarization field control structure (25) is -1 to +1 GPa.

5. The MicroLED lateral polarization field modulation structure as described in claim 1, characterized in that, The polarization field control structure (25) only covers the sidewalls of the multi-quantum well light-emitting layer (23) at the corresponding height, or covers the sidewall regions of the multi-quantum well light-emitting layer (23) within a range of 100-300 nm above and below.

6. The MicroLED lateral polarization field modulation structure as described in claim 1, characterized in that, The polarization field control structure (25) is prepared by PECVD, ALD, magnetron sputtering or low-pressure chemical vapor deposition.

7. The MicroLED lateral polarization field modulation structure as described in claim 1, characterized in that, The n-type semiconductor layer (24) has a transparent conductive layer (27) extending laterally to the cathode electrode (12) in the CMOS backplane (1) at its top, and a metal filling structure (26) that penetrates the insulating medium downward and is connected to the cathode electrode (12) at the bottom of the transparent conductive layer (27).

8. The MicroLED lateral polarization field modulation structure as described in claim 1, characterized in that, A microlens (3) is provided on the top of the MicroLED epitaxial structure.

9. The MicroLED lateral polarization field modulation structure as described in claim 1, characterized in that, The multi-quantum-well light-emitting layer (23) consists of 4 to 8 pairs of InGaN / GaN quantum wells, with a thickness of 2 to 4 nm for each quantum well and a thickness of 8 to 12 nm for the barrier layer.

10. The method for fabricating a MicroLED lateral polarization field modulation structure as described in claim 1, characterized in that, Includes the following steps: Step 1: Sequentially grow an n-type semiconductor layer, a multi-quantum-well light-emitting layer, and a p-type semiconductor layer on the substrate; Step 2: Perform metal bonding between the MicroLED pixel layer and the CMOS backplane; Step 3: Define MicroLED pixels by photolithography and etch to form Mesa structure. The etching depth penetrates the p-type semiconductor layer and the multi-quantum-well light-emitting layer and enters the n-type semiconductor layer. Step 4: In the region of the Mesa structure corresponding to the multi-quantum-well light-emitting layer on the sidewall, a polarization field control structure is formed by depositing a dielectric material with preset internal stress.

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