Micro-led device with spin regulation structure and preparation method thereof

Abstract

The application discloses a MicroLED device with a spin regulation structure and a preparation method thereof, and belongs to the technical field of MicroLED display, and solves the problem that the spin state of carriers and defect centers is not actively regulated in the prior art.The application comprises a CMOS driving back plate and a MicroLED epitaxial structure arranged on the back plate, and the MicroLED epitaxial structure comprises a p-type semiconductor layer, a multi-quantum well light-emitting layer and an n-type semiconductor layer arranged in sequence, and a spin regulation structure comprising a magnetic material is arranged on the side wall of the epitaxial structure corresponding to the multi-quantum well light-emitting layer.Compared with the prior art MicroLED side wall only adopting dielectric passivation, the spin regulation structure can be used to adjust the spin state of carriers and / or defect centers near the side wall, reduce the carrier combination allowed by defect-assisted capture and recombination, and reduce the probability of defect-assisted non-radiative recombination of the side wall, so that a new regulation dimension is provided for inhibiting defect-assisted non-radiative recombination of the side wall.

Description

Technical Field

[0001] This invention belongs to the field of MicroLED (Micro Light Emitting Diode Display) technology, specifically relating to MicroLED devices with spin modulation structures. This invention also relates to a method for fabricating MicroLED devices with spin modulation structures. Background Technology

[0002] As MicroLED pixel sizes shrink to below 10μm, the proportion of mesa sidewall area increases significantly, and sidewall defects have a more pronounced impact on device efficiency, brightness uniformity, and reliability. Vacancies, dangling bonds, and deep-level defects generated during Mesa etching are prone to forming Shockley-Read-Hall (non-radiative recombination channels), causing carrier loss in the sidewall region, resulting in decreased luminous efficiency, increased leakage current, and pixel performance dispersion.

[0003] Existing methods include wet remediation, thermal annealing, and treatment with Al2O3, SiO2, and SiN. x Methods such as sidewall passivation mainly suppress nonradiative recombination by reducing defect density or defect activity, but they do not actively regulate the spin state of charge carriers and defect centers. Defect-assisted recombination is affected not only by defect density and trapping cross-section, but also by the spin matching state of charge carriers and defect centers.

[0004] Therefore, it is necessary to introduce spin control structures with magnetic exchange, spin filtering, spin-orbit coupling or local magnetic field effects near the sidewalls of MicroLEDs to adjust the spin state of sidewall carriers and / or defect centers, reduce defect-assisted nonradiative recombination, and improve the luminous efficiency, uniformity and device consistency of small-sized MicroLEDs. Summary of the Invention

[0005] The purpose of this invention is to provide a MicroLED device with a spin-controlled structure, which solves the problem that existing methods do not actively control the spin state of charge carriers and defect centers.

[0006] Another object of the present invention is to provide a method for fabricating MicroLED devices with spin modulation structures.

[0007] The first technical solution adopted in this invention is: a MicroLED device with a spin control structure, including a CMOS (Complementary Metal Oxide Semiconductor) driving backplane and a MicroLED epitaxial structure disposed thereon. 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 sidewalls of the MicroLED epitaxial structure are provided with a spin control structure containing magnetic material corresponding to the multi-quantum well light-emitting layer.

[0008] The first technical solution of this invention is further characterized by: The spin control structure is a longitudinally arranged magnetic functional layer with a thickness of 1–200 nm. The magnetic functional layer is made of Fe, Co, Ni, CoFe, NiFe, CoFeB, FePt, CoPt and their alloys, or magnetic oxides such as Fe3O4, γ-Fe2O3, CoFe2O4 or NiFe2O4, or dilute magnetic semiconductor materials such as GaMnN, ZnMnO, ZnCoO, GaFeN.

[0009] The spin control structure also includes a spin-orbit coupling layer with a thickness of 1–30 nm disposed outside the magnetic functional layer. The spin-orbit coupling layer is made of Pt, Ta, W, Bi2Se3, Bi2Te3, Sb2Te3, WTe2, or MoTe2.

[0010] The spin control structure is a spin filtering functional layer, which includes a first magnetic functional layer, a non-magnetic spacer layer and a second magnetic functional layer arranged sequentially from the inside to the outside. The first magnetic functional layer and the second magnetic functional layer have the same or different magnetization directions and coercivity.

[0011] The first magnetic functional layer uses CoFeB with a thickness of 3–15 nm; the non-magnetic spacer layer uses MgO, Al2O3, Cu, or Ru with a thickness of 0.5–5 nm; the second magnetic functional layer uses CoFe, NiFe, or CoFeB with a thickness of 3–30 nm.

[0012] An insulating layer with a thickness of 0.5–20 nm is also provided between the spin control structure and the sidewall of the MicroLED epitaxial structure. The insulating layer is made of Al2O3, HfO2, SiO2, or SiN. x AlN or AlON.

[0013] The spin-controlled structure covers the sidewalls of the MicroLED epitaxial structure at the height corresponding to the multi-quantum-well light-emitting layer, and extends from the multi-quantum-well light-emitting layer to the p-type semiconductor layer and the n-type semiconductor layer by 20–500 nm, respectively.

[0014] The spin control structure covers 20% to 100% of the sidewall of the MicroLED epitaxial structure in the circumferential direction.

[0015] SiO2 and SiN are arranged on the outer side of the spin control structure. x Al2O3 or polymer protective layer.

[0016] The second technical solution adopted in this invention is: a method for fabricating a MicroLED device with a spin-controlled structure, wherein an n-type semiconductor layer, a multi-quantum-well light-emitting layer and a p-type semiconductor layer are sequentially formed on a substrate to obtain a MicroLED epitaxial structure and bonded to a CMOS driving backplane; the substrate is removed and the n-type semiconductor layer is thinned and then etched to form a Mesa structure; a magnetic material is deposited on the sidewall of the Mesa structure corresponding to the outside of the multi-quantum-well light-emitting layer to form a spin-controlled structure; an insulating dielectric material is deposited between the Mesa structures and a conductive material is filled through openings to form a metal-filled structure; and a transparent conductive layer electrically connected to the metal-filled structure is formed on the top of the n-type semiconductor layer.

[0017] The beneficial effects of this invention are as follows: Compared to existing MicroLED devices that only use dielectric passivation for the sidewalls, the spin-controlled MicroLED device and its fabrication method can adjust the spin state of charge carriers and / or defect centers near the sidewalls through magnetic exchange, spin filtering, spin-orbit coupling, or local magnetic field effects. This reduces the carrier combinations that allow defect-assisted trapping and recombination, and lowers the probability of sidewall defect-assisted nonradiative recombination, thus providing a new dimension for suppressing sidewall defect-assisted nonradiative recombination. It is particularly suitable for MicroLED microdisplay devices with pixel sizes less than 10 μm and a high sidewall area ratio, which is beneficial for improving luminous efficiency at low current densities and long-term device stability. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the MicroLED device with spin modulation structure of the present invention; Figure 2 This is a schematic diagram of the spin control structure in the MicroLED device with spin control structure of the present invention; Figure 3 This is a schematic diagram of the fabrication process of the MicroLED device with spin modulation structure according to the present invention.

[0019] In the diagram, 1. CMOS driver 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. Spin control structure; 26. Metal-filled structure; 27. Transparent conductive layer; 28. Insulating dielectric material. 251. Insulating layer, 252. First magnetic functional layer, 253. Non-magnetic spacer layer, 254. Second magnetic functional 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 device with a spin control structure, applicable to GaN-based, AlInGaP-based, and color-conversion MicroLED microdisplay devices. It includes a CMOS driving backplane 1, a MicroLED epitaxial structure disposed on the CMOS driving backplane 1, a spin control structure 25 disposed on the mesa sidewall of the MicroLED epitaxial structure, a bonding metal 21 for connecting the MicroLED epitaxial structure and the CMOS driving backplane 1, an insulating dielectric material 28 disposed around the mesa, a metal filling structure 26 for forming electrical connections, and a transparent conductive layer 27.

[0022] The MicroLED epitaxial structure is formed by mesa etching to create independent light-emitting units. The lateral dimensions of these units are preferably 1–50 μm, more preferably 2–10 μm. 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, sequentially arranged. The p-type semiconductor layer 22 is preferably made of Mg-doped p-GaN with a thickness of 50–500 nm, more preferably 100–300 nm. The multi-quantum-well light-emitting layer 23 preferably includes 3–10 pairs of InGaN / GaN quantum wells, with each quantum well having a thickness of 1.5–5 nm and a barrier layer thickness of 5–20 nm. The n-type semiconductor layer 24 is preferably made of Si-doped n-GaN with a thickness of 0.5–5 μm.

[0023] The spin modulation structure 25 is disposed on the mesa sidewall corresponding to the region of the multi-quantum-well light-emitting layer 23. The spin modulation structure 25 may only cover the corresponding height of the multi-quantum-well light-emitting layer 23, or it may extend from the multi-quantum-well light-emitting layer 23 to the p-type semiconductor layer 22 and the n-type semiconductor layer 24 by 20–500 nm, preferably extending 50–200 nm. By concentrating the spin modulation structure 25 near the light-emitting layer, its effect on the sidewall defect-assisted recombination region can be enhanced, and its impact on the p-type contact region, the n-type current extension region, and the forward light emission of the device can be reduced.

[0024] The spin control structure 25 includes a magnetic functional layer, a spin filtering functional layer, a spin-orbit coupling functional layer, or a combination of the above functional layers. The spin control structure 25 can be in direct contact with the sidewall of the MicroLED, or it can be spaced apart from the sidewall of the MicroLED by an insulating isolation layer 251. In a preferred embodiment, the spin control structure 25 includes a magnetic functional layer disposed outside the insulating isolation layer 251. The insulating isolation layer 251 is in contact with the mesa sidewall to reduce the risks of leakage current, metal diffusion, and interface recombination caused by direct contact between the magnetic material and the semiconductor. The magnetic functional layer is used to form magnetic exchange, a local magnetic field, or spin selection near the mesa sidewall.

[0025] The ultra-thin insulating layer 251 can be made of Al2O3, HfO2, SiO2, or SiN. x The material is AlN or AlON, with a thickness preferably of 0.5–20 nm, more preferably 1–5 nm. This thickness allows the local magnetic field or interface spin effect generated by the magnetic functional layer to influence the adjacent region of the sidewall while suppressing direct conductivity and interface diffusion.

[0026] The magnetic functional layer can be made of Fe, Co, Ni, CoFe, NiFe, CoFeB, FePt, CoPt and their alloys, or magnetic oxides such as Fe3O4, γ-Fe2O3, CoFe2O4 or NiFe2O4, or rare-field magnetic semiconductor materials such as GaMnN, ZnMnO, ZnCoO or GaFeN. The thickness of the magnetic functional layer is preferably 1–200 nm, more preferably 3–50 nm. CoFeB is preferably used as the magnetic functional layer. The thickness of the CoFeB film can be 3–30 nm, more preferably 5–20 nm. The CoFeB film has good continuous film formation capability, and its magnetization direction, saturation magnetization, and coercivity can be adjusted by the material composition, film thickness, and annealing conditions.

[0027] In a further embodiment, the spin control structure 25 includes a magnetic functional layer and a spin-orbit coupling layer. The magnetic functional layer is used to form a preset magnetization state, and the spin-orbit coupling layer is used to adjust the interfacial spin transport or enhance the coupling between spin and carrier motion. The spin-orbit coupling layer may be made of Pt, Ta, W, Bi₂Se₃, Bi₂Te₃, Sb₂Te₃, WTe₂, or MoTe₂, and its thickness is preferably 1–30 nm, more preferably 2–10 nm.

[0028] In another embodiment, the spin control structure 25 includes a first magnetic functional layer 252, a non-magnetic spacer layer 253, and a second magnetic functional layer 254. The first magnetic functional layer 252 and the second magnetic functional layer 254 have the same or different magnetization directions and coercivity, and the non-magnetic spacer layer 253 is disposed between them to form a composite spin filter structure. The first magnetic functional layer 252 can be made of CoFeB with a thickness of 3–15 nm; the non-magnetic spacer layer 253 can be made of MgO, Al2O3, Cu, or Ru with a thickness of 0.5–5 nm; and the second magnetic functional layer 254 can be made of CoFe, NiFe, or CoFeB with a thickness of 3–30 nm.

[0029] The spin control structure 25 does not serve as the main current injection path for the MicroLED, and it is preferably electrically isolated from the p-type semiconductor layer 22, the n-type semiconductor layer 24, and the transparent conductive layer 27. SiO2 or SiN may be disposed on the outer side of the spin control structure 25. x Al2O3 or polymer protective layers are used to reduce the risk of oxidation of magnetic materials and their contact with subsequent metal interconnect structures.

[0030] The bonding metal 21 can adopt Au, AuSn, Cu, CuSn, In, Au-Au, or Cu-Cu bonding structures, and its thickness is preferably 0.2–5 μm. The insulating dielectric material 28 can be SiO2 or SiN. x The metal filling structure 26 can be made of Cu, W, Al, or a composite metal thereof, and is used to connect the top transparent conductive layer 27 to the cathode electrode 12 in the CMOS driving backplane 1. The transparent conductive layer 27 can be made of ITO, IZO, or AZO, and its thickness is preferably 30–300 nm.

[0031] The present invention also provides a method for fabricating the above-mentioned MicroLED device, including the steps of fabricating a MicroLED epitaxial structure, bonding the MicroLED epitaxial structure to a CMOS driving backplane, removing the epitaxial growth substrate, etching to form a MicroLED mesa, repairing damage to the mesa sidewalls, forming a spin control structure on the corresponding sidewalls of the multi-quantum well light-emitting layer, forming an insulating dielectric and metal filling structure, and forming a transparent conductive layer.

[0032] Through the above structure, this invention, based on the traditional chemical passivation to reduce sidewall defect density, further utilizes a spin modulation structure to adjust the spin state of charge carriers and / or defect centers near the sidewalls, thereby reducing carrier combinations that allow defect-assisted trapping and recombination, and reducing sidewall nonradiative recombination. Compared with existing MicroLED sidewall structures that only employ dielectric passivation, this invention adds a spin modulation structure to the region of the mesa sidewall corresponding to the multi-quantum-well light-emitting layer. Through magnetic exchange, spin filtering, spin-orbit coupling, or the action of a local magnetic field, the spin state of charge carriers and / or defect centers near the sidewalls is adjusted, thus providing a new dimension of modulation for suppressing sidewall defect-assisted nonradiative recombination.

[0033] The spin modulation structure of this invention is mainly located in the sidewall region corresponding to the multiple quantum wells, without changing the epitaxial structure of the MicroLED body. It has minimal impact on p-type contacts, n-type current expansion, and the forward light emission path, and is compatible with existing MicroLED mesa etching, sidewall passivation, thin film deposition, backplane bonding, dielectric filling, metal interconnection, and transparent electrode processes. It is particularly suitable for MicroLED devices with pixel sizes smaller than 10μm and a high sidewall area ratio, which helps improve luminous efficiency at low current densities and long-term device stability.

[0034] Furthermore, the spin-controlled structure can interact with Al2O3, SiO2, or SiN. x By combining traditional sidewall passivation layers, the density of sidewall defects and leakage current are reduced, while further restricting the participation of remaining defect centers in carrier recombination. This is beneficial for improving the luminous efficiency, brightness uniformity and pixel consistency of small-sized MicroLEDs.

[0035] Example 2 This invention provides a MicroLED device with a spin control structure. Based on Embodiment 1, the spin control structure 25 can be continuously arranged circumferentially along the sidewalls of the MicroLED mesa to form a closed or nearly closed annular spin control structure; alternatively, it can be spaced apart circumferentially along the mesa to form multiple mutually separated spin control regions. For a rectangular MicroLED, the spin control structure 25 can be disposed on all four sidewalls or only on a pair of opposite sidewalls. Its circumferential coverage ratio can be 20% to 100%, preferably 50% to 100%.

[0036] Example 3 The present invention provides a MicroLED device with a spin control structure. Based on Example 1, a microlens 3 is further formed on the top of the MicroLED epitaxial structure to improve light extraction efficiency and improve emission angle distribution.

[0037] Example 4 This invention provides a MicroLED device with a spin modulation structure, such as... Figure 1 and Figure 2 As shown, it includes a CMOS driving backplane 1, a MicroLED layer 2, and a microlens 3 disposed on the light-emitting side of the device.

[0038] The CMOS driving backplane 1 includes an anode electrode 11 and a cathode electrode 12. The anode electrode 11 can be made of Al, Cu, W, TiN, or a composite metal thereof, with a thickness of 0.3–3 μm; the cathode electrode 12 can be made of Al, Cu, Ti, TiN, or W, with a thickness of 0.3–3 μm. The CMOS driving backplane 1 internally houses pixel driving transistors, current sources, storage capacitors, and row and column addressing circuits to provide driving current to the MicroLED.

[0039] MicroLED layer 2 is connected to CMOS driving backplane 1 via bonding metal 21. Bonding metal 21 can be AuSn, CuSn, In, Au-Au, or Cu-Cu structure, with a thickness of 0.2–5 μm. In one specific embodiment, bonding metal 21 is AuSn eutectic metal, with a bonding temperature of 280–320 °C and a bonding pressure of 1–20 MPa.

[0040] The MicroLED epitaxial structure in MicroLED layer 2 includes a p-type semiconductor layer 22, a multi-quantum-well light-emitting layer 23, and an n-type semiconductor layer 24, sequentially arranged from the side near the CMOS driving backplane 1 towards the light-emitting side. The p-type semiconductor layer 22 is made of Mg-doped p-GaN with a thickness of 100–300 nm; the multi-quantum-well light-emitting layer 23 includes 4–8 pairs of InGaN / GaN quantum wells, with each InGaN quantum well having a thickness of 2–4 nm and the GaN barrier layer having a thickness of 8–12 nm; the n-type semiconductor layer 24 is made of Si-doped n-GaN with a thickness of 1–5 μm and a doping concentration of 1 × 10⁻⁶. 18 ~5×10 18 cm 3 .

[0041] The lateral dimension of the MicroLED mesa is 2–20 μm, preferably 3–8 μm, and the sidewall tilt angle is 70°–90°. The mesa is etched through the n-type semiconductor layer 24 and the multi-quantum-well light-emitting layer 23, and enters the p-type semiconductor layer 22 or extends to the vicinity of the bonding interface to achieve electrical isolation between pixels.

[0042] The spin modulation structure 25 is disposed on the mesa sidewall corresponding to the region of the multi-quantum-well light-emitting layer 23, and extends 50–200 nm into the p-type semiconductor layer 22 and the n-type semiconductor layer 24, respectively. This structure does not serve as the main conductive path of the device; it is primarily used to form a local spin modulation region near the multi-quantum-well sidewall.

[0043] In a preferred embodiment, the spin control structure 25 includes an Al2O3 insulating layer 251 with a thickness of 1–5 nm and a CoFeB first magnetic functional layer 252 with a thickness of 5–20 nm. The Al2O3 insulating layer 251 is in direct contact with the MicroLED sidewalls, serving to reduce the sidewall interface states after etching, isolate the CoFeB and GaN sidewalls, and limit metal diffusion. The CoFeB first magnetic functional layer 252 is disposed outside the Al2O3 insulating layer 251, and its magnetization state creates magnetic exchange or a local magnetic field in the adjacent region of the sidewalls.

[0044] SiO2 and SiN with a thickness of 10-100 nm can be formed on the outer side of the first magnetic functional layer 252 of CoFeB. x Alternatively, an Al2O3 protective layer may be used to prevent CoFeB oxidation and to electrically isolate it from the subsequent metal-filled structure 26.

[0045] In another embodiment, the spin control structure 25 adopts an Al2O3 / Fe3O4 composite structure. The Al2O3 insulating layer 251 has a thickness of 1–5 nm, and the Fe3O4 first magnetic functional layer 252 has a thickness of 5–50 nm. Fe3O4 has a relatively high resistivity, which can reduce the risk of parasitic leakage between the magnetic functional layer and the MicroLED sidewalls.

[0046] In a further embodiment, the spin control structure 25 includes an Al2O3 insulating layer 251, a CoFeB first magnetic functional layer 252, an MgO non-magnetic spacer layer 253, and a CoFe or NiFe second magnetic functional layer 254. The thickness of the CoFeB first magnetic functional layer 252 is 3–10 nm, the thickness of the MgO non-magnetic spacer layer 253 is 0.5–3 nm, and the thickness of the second magnetic functional layer 254 is 5–20 nm. The first magnetic functional layer 252 and the second magnetic functional layer 254 may have different coercivities, enabling them to form a preset parallel, antiparallel, or angled magnetization state.

[0047] Example 5 This invention provides the technical principle of a MicroLED device with a spin-controlled structure. Spin-related defect-assisted recombination can be described using a modified SRH (Shockley-Read-Hall, non-radiative recombination channel) recombination model. The traditional defect-assisted recombination rate is:

[0048] in, and These are electron concentration and hole concentration, respectively. Intrinsic carrier concentration, and These are the equivalent trapping lifetimes for electrons and holes, respectively. The equivalent electron concentration corresponding to the defect energy level This represents the equivalent hole concentration corresponding to the defect energy level.

[0049] The equivalent spin polarization of electrons and holes can be expressed as follows:

[0050]

[0051] in, and This indicates the electron concentration in the two spin states. and This represents the hole concentration in the two spin states.

[0052] After considering spin selection, the sidewall defect-assisted recombination rate can be expressed as:

[0053] in, This represents the defect-assisted recombination rate without a spin control structure. This represents the equivalent spin state of the defect center. This represents the spin correction function determined by the spin matching relationship between the charge carrier and the defect center.

[0054] In a simplified model used to illustrate the trend of regulation, it can be further expressed as:

[0055] in, The effective coefficient for spin modulation is related to the magnetic material, interface state, functional layer thickness, carrier scattering, and device operating temperature. The above expression illustrates the trend of spin modulation's effect on defect-assisted recombination, but does not limit actual devices to conforming solely to this linear relationship.

[0056] During device operation, the spin modulation structure 25, through magnetic exchange, local magnetic field, spin filtering, or spin-orbit coupling, causes a non-random spin distribution of charge carriers and / or defect centers near the mesa sidewalls, reducing the number of charge carrier combinations that can satisfy defect trapping and recombination conditions, thereby reducing sidewall non-radiative recombination. The insulating isolation layer 251 simultaneously passivates etch defects and prevents direct contact between the magnetic functional layer and the semiconductor, thus avoiding new leakage paths.

[0057] Example 6 This invention provides a method for fabricating MicroLED devices with spin modulation structures, such as... Figure 3 As shown, it includes the following steps: Step 1: An n-type semiconductor layer 24, a multi-quantum-well light-emitting layer 23, and a p-type semiconductor layer 22 are sequentially formed on a growth substrate to obtain a MicroLED epitaxial structure.

[0058] Step 2: Form a p-type contact electrode and bonding metal 21 on the surface of the p-type semiconductor layer 22, and align and bond the MicroLED epitaxial structure to the CMOS driving backplane 1 so that the p-type semiconductor layer 22 is electrically connected to the anode electrode 11 of the CMOS driving backplane 1.

[0059] Step 3: Remove the growth substrate of the MicroLED epitaxial structure by laser lift-off, wet etching, mechanical polishing or dry etching, and thin and planarize the exposed n-type semiconductor layer 24.

[0060] Step 4: Define the MicroLED pixel pattern by photolithography, and form the Mesa structure by ICP (inductively coupled plasma) etching. The etching depth penetrates the n-type semiconductor layer 24 and the multi-quantum well light-emitting layer 23, and enters the p-type semiconductor layer 22 or extends to the vicinity of the bonding interface to achieve electrical isolation between pixels.

[0061] Step 5: Perform wet repair, low-damage plasma treatment, or thermal annealing on the Mesa sidewalls to reduce etching damage and sidewall defects.

[0062] Step 6: An insulating isolation layer 251 is formed in the region of the Mesa sidewall corresponding to the multi-quantum-well light-emitting layer 23. A magnetic functional layer, a spin filtering functional layer, and / or a spin-orbit coupling functional layer are deposited on the outside of the insulating isolation layer 251 to form a spin control structure 25. The spin control structure 25 can be patterned by sidewall self-alignment, dielectric windowing, tilted deposition, or partial removal after overall deposition.

[0063] Step 7: A protective layer is formed on the outside of the spin control structure 25, and an insulating dielectric material 28 is deposited between the Mesa. The surface is then planarized by chemical mechanical polishing or dry etching.

[0064] Step 8: Electrode connection vias are formed in the insulating dielectric material 28 by photolithography and etching, and Cu, W, Al or other conductive materials are filled in the vias to form a metal filling structure 26 that connects to the cathode electrode 12 of the CMOS driving backplane 1.

[0065] Step 9: Form a transparent conductive layer 27 on top of the n-type semiconductor layer 24, and electrically connect the transparent conductive layer 27 to the metal filling structure 26 to form an n-type side current transmission path.

[0066] Step 10: Form a microlens 3 structure above the transparent conductive layer 27 to improve light extraction efficiency and adjust the light emission angle.

[0067] Step 11: Complete device cleaning, annealing, electrical testing and optical calibration to obtain a MicroLED device with sidewall spin modulation structure 25.

Claims

1. A MicroLED device with a spin modulation structure, characterized in that, The microLED epitaxial structure includes a CMOS driving backplane (1) and a microLED epitaxial structure disposed thereon. 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 spin control structure (25) containing magnetic material corresponding to the multi-quantum well light-emitting layer (23).

2. The MicroLED device with a spin modulation structure as described in claim 1, characterized in that, The spin control structure (25) is a longitudinally arranged magnetic functional layer with a thickness of 1 to 200 nm. The magnetic functional layer uses Fe, Co, Ni, CoFe, NiFe, CoFeB, FePt, CoPt and their alloys, or uses magnetic oxides Fe3O4, γ-Fe2O3, CoFe2O4 or NiFe2O4, or uses dilute magnetic semiconductor materials GaMnN, ZnMnO, ZnCoO, GaFeN.

3. The MicroLED device with a spin modulation structure as described in claim 2, characterized in that, The spin control structure (25) also includes a spin-orbit coupling layer with a thickness of 1 to 30 nm disposed on the outside of the magnetic functional layer. The spin-orbit coupling layer is made of Pt, Ta, W, Bi2Se3, Bi2Te3, Sb2Te3, WTe2 or MoTe2.

4. The MicroLED device with a spin modulation structure as described in claim 1, characterized in that, The spin control structure (25) is a spin filter functional layer. The spin filter functional layer includes a first magnetic functional layer (252), a non-magnetic spacer layer (253), and a second magnetic functional layer (254) arranged sequentially from the inside to the outside. The first magnetic functional layer (252) and the second magnetic functional layer (254) have the same or different magnetization directions and coercivity.

5. The MicroLED device with a spin modulation structure as described in claim 4, characterized in that, The first magnetic functional layer (252) is made of CoFeB and has a thickness of 3 to 15 nm; the non-magnetic spacer layer (253) is made of MgO, Al2O3, Cu or Ru and has a thickness of 0.5 to 5 nm; the second magnetic functional layer (254) is made of CoFe, NiFe or CoFeB and has a thickness of 3 to 30 nm.

6. The MicroLED device with a spin modulation structure as described in claim 1, characterized in that, An insulating isolation layer (251) with a thickness of 0.5–20 nm is further disposed between the spin control structure (25) and the sidewall of the MicroLED epitaxial structure. The insulating isolation layer (251) is made of Al2O3, HfO2, SiO2, or SiN. x AlN or AlON.

7. The MicroLED device with a spin modulation structure as described in claim 1, characterized in that, The spin control structure (25) covers the sidewall of the MicroLED epitaxial structure at the height corresponding to the multi-quantum well light-emitting layer (23), and extends from the multi-quantum well light-emitting layer (23) to the p-type semiconductor layer (22) and the n-type semiconductor layer (24) by 20 to 500 nm respectively.

8. The MicroLED device with a spin modulation structure as described in claim 1, characterized in that, The spin control structure (25) has a circumferential coverage ratio of 20% to 100% along the sidewall of the MicroLED epitaxial structure.

9. The MicroLED device with a spin modulation structure as described in claim 1, characterized in that, The outer side of the spin control structure (25) is provided with SiO2 and SiN. x Al2O3 or polymer protective layer.

10. The method for fabricating a MicroLED device with a spin modulation structure as described in claim 1, characterized in that, An n-type semiconductor layer, a multi-quantum-well light-emitting layer, and a p-type semiconductor layer are sequentially formed on a substrate to obtain a MicroLED epitaxial structure, which is then bonded to a CMOS driving backplane. After removing the substrate and thinning the n-type semiconductor layer, a Mesa structure is formed by etching. Magnetic material is deposited on the sidewalls of the Mesa structure corresponding to the outside of the multi-quantum-well light-emitting layer to form a spin control structure. Insulating dielectric material is deposited between the Mesa structures, and conductive material is filled through openings to form a metal-filled structure. A transparent conductive layer electrically connected to the metal-filled structure is formed on the top of the n-type semiconductor layer.

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