GaN-based spin light emitting device and method of fabricating the same

Abstract

The application discloses a GaN-based spin light-emitting device and a preparation method thereof. The device comprises a metal substrate, a GaN-based quantum light-emitting structure, an insulating tunnel layer, a ferromagnetic metal layer and a metal protective layer which are stacked from top to bottom. The GaN-based quantum light-emitting structure comprises an electron blocking layer, a hole transport layer, a radiative recombination layer and an electron transport layer which are stacked in sequence along the surface of the metal substrate. A two-dimensional material insertion layer composed of 1-3 layers of graphene is arranged between the insulating tunnel layer and the ferromagnetic metal layer or between the GaN-based quantum light-emitting structure and the insulating tunnel layer. By inserting a few layers of graphene above or below the insulating tunnel layer, impedance mismatch caused by direct contact of the ferromagnetic metal electrode with the semiconductor through the insulating layer hole is avoided, spin current tunneling is facilitated, the spin current can be expanded, and the injection efficiency of the spin current is improved. By changing the insertion position of the two-dimensional material insertion layer, the polarization direction of the injected current and the spin light-emitting characteristics can be controlled.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of semiconductor spintronics, and in particular to a GaN-based spin light emitting device and a preparation method thereof. BACKGROUND

[0002] Since the discovery of giant magnetoresistance, spintronics has become a hot research topic in the international academic field as a new discipline. People hope to overcome the physical limits of device size and integration density by manipulating the spin of electrons, and develop new devices with lower power consumption, faster data processing and higher integration density, bringing a qualitative leap to the development of modern information technology. As one of the main applications, semiconductor spin light emitting devices are expected to integrate logic, storage and communication functions, and become new, high-performance multifunctional optoelectronic devices, which have good application prospects in display, communication and monitoring. At present, semiconductor lighting technology is relatively mature, but the polarization degree of these traditional light sources is very low, which is difficult to meet the requirements of new applications for light source polarization degree.

[0003] The main problem of low polarization rate of semiconductor spin light emitting devices is the low spin current injection efficiency. Direct contact of ferromagnetic material and semiconductor will cause resistance mismatch, which greatly reduces the injection efficiency of the electrical injection method. A common way to solve the resistance mismatch is to insert an extremely thin insulating layer as a tunneling layer in the interface between the ferromagnetic metal and the semiconductor. Polarized electrons pass through the tunneling layer to form a stable polarization current in the semiconductor, thereby improving the spin polarization rate. In the early stage, research mainly focused on tunnel junctions with amorphous Al2O3 as insulating material. For example, Van't Erve et al. prepared a spin light LED using a Fe / Al2O3 tunnel junction, and the light spin polarization rate at 4.5K was 40%. Since 2001, J. Mattho et al. theoretically predicted that a Fe / MgO / Fe magnetic tunnel junction can obtain a tunneling magnetoresistance (TMR) as high as 1000% by replacing the amorphous Al2O3 material with a single-crystal MgO. Using MgO as an insulating material to form a tunnel junction has become the mainstream of research. Although satisfactory results have been achieved by using an insulating tunnel junction, in order to realize electron tunneling, the thickness of Al2O3 or MgO is usually controlled between 1-2nm. Due to the thin thickness, it is inevitable to cause perforation or non-densification problems, thereby leading to a decrease in injection efficiency. In addition, when Al2O3 or MgO is combined with ferromagnetic metal, interdiffusion at the interface, lattice mismatch and pinned magnetic moment at the interface also seriously affect the spin-dependent transport.

[0004] Therefore, it is necessary to provide a good structure and process to improve the interface quality and thereby improve the spin injection efficiency. SUMMARY

[0005] The present application aims at overcoming the deficiencies in the prior art, and provides a GaN-based spin light emitting device and a preparation method thereof.

[0006] To achieve the above object, the technical scheme of the present application is as follows:

[0007] A GaN-based spin light emitting device comprises a metal substrate, a GaN-based quantum light emitting structure, an insulating tunnel layer, a ferromagnetic metal layer and a metal protective layer which are stacked from top to bottom, wherein the GaN-based quantum light emitting structure comprises an electron blocking layer, a hole transport layer, a radiative recombination layer and an electron transport layer which are stacked in sequence along the surface of the metal substrate; a two-dimensional material insertion layer is arranged between the insulating tunnel layer and the ferromagnetic metal layer or between the GaN-based quantum light emitting structure and the insulating tunnel layer.

[0008] Preferably, the two-dimensional material insertion layer is 1-3 layers of graphene.

[0009] Preferably, the electron transport layer is n-type GaN; the radiative recombination layer is an In x Ga 1-x N / In y Ga 1-y N quantum well structure with several periods; the hole transport layer is p-type GaN; and the electron blocking layer is heavily doped p++ type GaN.

[0010] Preferably, the insulating tunnel layer is MgO with a thickness of 1-2 nm, and the ferromagnetic metal layer is CoFeB or NiFe with a thickness of 20-30 nm.

[0011] Preferably, the metal protective layer is Ru with a thickness of 10-20 nm.

[0012] Preferably, the metal substrate is copper.

[0013] A preparation method of the GaN-based spin light emitting device is provided, comprising the following steps:

[0014] 1) growing a GaN buffer layer, an electron transport layer, a radiative recombination layer, a hole transport layer and an electron blocking layer in sequence on a sapphire substrate by metal organic chemical vapor deposition technology;

[0015] 2) bonding a metal substrate on the electron blocking layer, and peeling off the sapphire substrate to expose the GaN buffer layer;

[0016] 3) thinning the GaN buffer layer and the electron transport layer by inductively coupled plasma etching technology to obtain a GaN-based quantum light emitting structure;

[0017] 4) fabricating an insulating tunneling layer, a two-dimensional material insertion layer, a ferromagnetic metal layer and a metal protection layer on the surface of the GaN-based quantum light-emitting structure to form a tunnel junction and a spin injection electrode, wherein the insulating tunneling layer, the ferromagnetic metal layer and the metal protection layer are prepared by a magnetron sputtering process, the ferromagnetic metal layer is located above the insulating tunneling layer, and the metal protection layer is located above the ferromagnetic metal layer; the two-dimensional material insertion layer with an electrode pattern is exposed from photoresist by a mechanical exfoliation process combined with a maskless laser direct writing technique, and the two-dimensional material insertion layer is located between the insulating tunneling layer and the ferromagnetic metal layer or between the GaN-based quantum light-emitting structure and the insulating tunneling layer;

[0018] 5) peeling off the remaining photoresist to obtain a tunnel junction and a spin injection electrode with an electrode pattern.

[0019] Preferably, the two-dimensional material insertion layer is 1-3 layers of graphene.

[0020] Preferably, step 4 specifically comprises:

[0021] The graphene bulk sheet is repeatedly pasted and peeled off on a transparent tape to obtain a graphene layered sheet;

[0022] The graphene layered sheet is transferred to the surface of the GaN-based quantum light-emitting structure, and a two-dimensional material insertion layer with an electrode shape is prepared by a maskless laser direct writing technique;

[0023] An insulating tunneling layer with a thickness of 1-2 nm is grown on the two-dimensional material insertion layer by a radio frequency sputtering process, the target material is MgO, the growth pressure is 0.5 Pa, and the working gas is argon;

[0024] A ferromagnetic metal layer with a thickness of 20-30 nm and a metal protection layer with a thickness of 10-20 nm are grown on the insulating tunneling layer by a direct current sputtering process, the target materials are CoFeB and Ru respectively, the growth pressures are 0.5 Pa and 0.6 Pa respectively, and the working gas is argon.

[0025] Preferably, step 4 specifically comprises:

[0026] An insulating tunneling layer with a thickness of 1-2 nm is grown on the surface of the GaN-based quantum light-emitting structure by a radio frequency sputtering process, the target material is MgO, the growth pressure is 0.5 Pa, and the working gas is argon;

[0027] The graphene bulk sheet is repeatedly pasted and peeled off on a transparent tape to obtain a graphene layered sheet;

[0028] The graphene layered sheet is transferred to the surface of the insulating tunneling layer, and a two-dimensional material insertion layer with an electrode shape is prepared by a maskless laser direct writing technique.

[0029] The ferromagnetic metal layer of 20-30 nm and the metal protective layer of 10-20 nm are grown on the two-dimensional material insertion layer by using a direct current sputtering process, the target materials are CoFeB and Ru respectively, the growth pressure is 0.5 Pa and 0.6 Pa respectively, and the working gas is argon.

[0030] Compared with the prior art, the application has the following beneficial effects:

[0031] (1) In the application, MgO with a spin filtering effect is used as an insulating tunneling layer, and CoFeB with a high spin polarization rate and a lattice matching with MgO is used as a ferromagnetic metal layer. The Ru metal protective layer can prevent the ferromagnetic metal layer from being oxidized and affecting the injection current polarization rate.

[0032] (2) After the epitaxial growth of the GaN buffer layer, the electron transport layer, the radiative recombination layer, the hole transport layer and the electron blocking layer, the electron blocking layer is bonded with the metal substrate through a metal bonding technology, and the sapphire substrate is removed through a laser stripping technology to expose the GaN buffer layer. After the GaN buffer layer and the electron transport layer are thinned, a spin injection junction is grown on the surface of the electron transport layer, which can reduce the transmission distance of the spin-polarized electrons before radiative recombination and reduce spin scattering. The design of the inverted spin structure can not only maintain the high-quality epitaxial growth of the material, but also reduce the transmission distance of the polarized electrons as much as possible, which is beneficial to the improvement of the polarization rate of the spin LED.

[0033] (3) The two-dimensional material insertion layer is arranged above or below the insulating tunneling layer, which can avoid the direct contact between the ferromagnetic metal and the semiconductor due to the perforation of the insulating tunneling layer, and avoid the decrease of the spin injection efficiency caused by impedance mismatch. By using extremely thin and uniform graphene material as the two-dimensional material insertion layer, a few-layer two-dimensional material is inserted above or below the insulating tunneling layer, which avoids the direct contact between the ferromagnetic metal and the semiconductor, thereby improving the spin injection efficiency.

[0034] (4) The application takes advantage of the micron-level long spin diffusion length of graphene at room temperature, inserts graphene as a two-dimensional material insertion layer in the tunnel junction structure, so that the spin current under the spin injection electrode is expanded, the transport length of the spin electron under the spin injection electrode is increased, and the device performance is improved.

[0035] (5) The application plays a regulating role of in-plane magnetic anisotropy and perpendicular magnetic anisotropy of ferromagnetic material by inserting a two-dimensional material insertion layer above or below the insulating tunneling layer. Due to the weak spin-orbit coupling and interaction between transition metal atoms and graphene, in-plane magnetic anisotropy is often exhibited. Therefore, by inserting a two-dimensional material insertion layer above the insulating tunneling layer, CoFeB is in contact with graphene, and the system is easy to exhibit in-plane magnetic anisotropy. When 3d transition metal Fe or Co is deposited on the insulating tunneling layer, due to the hybridization of metal 3d electrons and O 2p orbitals, it is easy to cause perpendicular anisotropy. Therefore, by inserting a two-dimensional material insertion layer below the insulating tunneling layer, CoFeB is in contact with MgO, and the system is easy to exhibit perpendicular magnetic anisotropy. BRIEF DESCRIPTION OF DRAWINGS

[0036] Figure 1 Structure diagram of a GaN-based spin light-emitting device of Example One of the application;

[0037] Figures 2-4 Process flow diagram of a preparation method of a GaN-based spin light-emitting device of Example One of the application;

[0038] Figure 5 Structure diagram of a GaN-based spin light-emitting device of Example Two of the application;

[0039] Figure 6 Process flow diagram of Step 4 of a GaN-based spin light-emitting device of Example Two of the application;

[0040] Figure 7 Forward magnetic field circularly polarized electroluminescence spectrum diagram of a GaN-based spin light-emitting device of Example One of the application;

[0041] Figure 8 Forward magnetic field circularly polarized electroluminescence spectrum diagram of a GaN-based spin light-emitting device of a comparative example of the application;

[0042] The symbols are as follows: 1, metal substrate; 2, GaN-based quantum light-emitting structure; 21, electron blocking layer; 22, hole transport layer; 23, radiative recombination layer; 24, electron transport layer; 25, GaN buffer layer; 3, two-dimensional material insertion layer; 4, insulating tunneling layer; 5, ferromagnetic metal layer; 6, metal protection layer; 7, sapphire substrate. DETAILED DESCRIPTION

[0043] The present application will be further explained with reference to the drawings and specific embodiments. The drawings of the present application are only schematic and are non-limiting according to the scope of the present application. As such, the specific proportions of the various layers in the figures are not to be understood as being critical, and should not be interpreted as limiting the scope of the present application. The relative dimensions of the various drawing elements in the figures are not necessarily to scale, and may be exaggerated or drawn smaller than actual size for the sake of clarity.

[0044] Embodiment 1

[0045] Reference Figure 1 In an embodiment of the present application, a GaN-based spin light emitting device is provided, which comprises, from top to bottom, a metal substrate 1, a GaN-based quantum light emitting structure 2, an insulating tunnel layer 4, a ferromagnetic metal layer 5 and a metal protective layer 6. The metal substrate 1 is copper. The GaN-based quantum light emitting structure 2 comprises, from top to bottom, an electron blocking layer 21, a hole transport layer 22, a radiative recombination layer 23 and an electron transport layer 24. Specifically, the electron transport layer 24 is n-type GaN; the radiative recombination layer 23 is In x Ga 1-x N / In y Ga 1-y N(x, y are determined according to the wavelength of light) quantum well structure; the hole transport layer 22 is p-type GaN; and the electron blocking layer 21 is heavily doped p++ GaN. In one embodiment, the electron transport layer 24 is Si-doped n-type GaN with a thickness of 100 nm, the radiative recombination layer 23 is In x Ga 1-x N / In y Ga 1-y N(3 nm / 1.5 nm) quantum well structure, the hole transport layer 22 is Mg-doped p-type GaN with a thickness of 200 nm, and the electron blocking layer 21 has a thickness of 10 nm. A two-dimensional material insertion layer 3 is provided between the GaN-based quantum light emitting structure 2 and the insulating tunnel layer 4. Specifically, the two-dimensional material insertion layer 3 is 1-3 layers of graphene with a thickness of about 1 nm. The insulating tunnel layer 4 is MgO with a thickness of 1-2 nm, and the ferromagnetic metal layer 5 is CoFeB or NiFe with a thickness of 20-30 nm. The metal protective layer 6 is Ru with a thickness of 10-20 nm.

[0046] From the material selection aspect, MgO with spin filtering effect is used as the insulating tunneling layer 4 in the embodiment of the present application, and CoFeB with high spin polarization rate is used as the ferromagnetic metal layer 5 which is lattice matched with MgO. The metal protective layer 6 can prevent the ferromagnetic metal layer 5 from being oxidized, which affects the injection current polarization rate. Graphene is used as the two-dimensional material insertion layer 3 in the embodiment of the present application, which avoids the impedance mismatch caused by the direct contact of the ferromagnetic metal layer 5 with the semiconductor through the hole in the insulating tunneling layer 4, and is conducive to the efficient tunneling of the spin current; at the same time, since graphene has a long spin diffusion length, it can also play a current expansion role on the spin current, thereby greatly improving the injection efficiency of the spin current. When 3d transition metal Fe or Co is deposited on MgO, due to the hybridization of metal 3d electrons and O 2p orbitals, it is easy to cause perpendicular anisotropy. The two-dimensional material insertion layer 3 with graphene inserted below MgO, and CoFeB in contact with MgO, makes the insulating tunneling layer 4 / ferromagnetic metal layer 5 system exhibit perpendicular magnetic anisotropy.

[0047] The embodiment of the present application also proposes a preparation method of the GaN-based spin light-emitting device, comprising the following steps:

[0048] (1) referring to Figure 2 , a GaN buffer layer 25, an electron transport layer 24, a radiative recombination layer 23, a hole transport layer 22 and an electron blocking layer 21 are sequentially grown on a sapphire substrate 7 by metal organic chemical vapor deposition (MOCVD) technology; specifically, the thickness of the GaN buffer layer 25 is 50 nm, the electron transport layer 24 is Si-doped n-type GaN with a thickness of 2 μm, the radiative recombination layer 23 is a 5-period ultra-thin In x Ga 1-x N / In y Ga 1-y N quantum well structure with a thickness of 3 nm / 1.5 nm (x, y are determined according to the emission wavelength), the hole transport layer 22 is Mg-doped p-type GaN with a thickness of 200 nm, and the electron blocking layer 21 is heavily doped p++ type GaN with a thickness of 10 nm.

[0049] (2) referring to Figure 3 , a metal substrate 1 is bonded on the electron blocking layer 21, and the sapphire substrate 7 is peeled off to expose the GaN buffer layer 25; specifically, the metal substrate 1 is copper, the electron blocking layer 21 is bonded with the metal substrate 1, the sapphire substrate 7 is peeled off, and the GaN buffer layer 25 is exposed.

[0050] (3) referring to Figure 4The GaN buffer layer 25 and the electron transport layer 24 are thinned by using an inductively coupled plasma etching technology (ICP) to obtain a GaN-based quantum light emitting structure 2. Specifically, the GaN buffer layer 25 is removed by using the ICP process, and the electron transport layer 24 is thinned to about 100 nm.

[0051] (4) A two-dimensional material insertion layer 3, an insulating tunneling layer 4, a ferromagnetic metal layer 5 and a metal protective layer 6 are prepared on the surface of the GaN-based quantum light emitting structure 2 to form a tunnel junction and a spin injection electrode. The insulating tunneling layer 4, the ferromagnetic metal layer 5 and the metal protective layer 6 are prepared by using a magnetron sputtering process. The ferromagnetic metal layer 5 is located above the insulating tunneling layer 4, and the metal protective layer 6 is located above the ferromagnetic metal layer 5. The two-dimensional material insertion layer 3 is prepared by using a mechanical exfoliation process combined with a maskless laser direct writing technology, and is arranged between the light emitting structure 2 and the insulating tunneling layer 4, i.e. the two-dimensional material insertion layer 3 is arranged below the insulating tunneling layer 4. Specifically, the two-dimensional material insertion layer 3 is 1-3 layers of graphene with a thickness of about 1 nm.

[0052] In specific embodiments, step 4 specifically includes:

[0053] The graphene bulk flake is repeatedly pasted and peeled off on the transparent tape to obtain a graphene layered flake.

[0054] The graphene layered flake is transferred to the surface of the GaN-based quantum light emitting structure 2. Specifically, the graphene layered flake on the transparent tape is transferred to the GaN-based quantum light emitting structure 2. After a period of time, the transparent tape is slowly peeled off, so that the graphene is left on the GaN-based quantum light emitting structure 2.

[0055] The two-dimensional material insertion layer 3 with an electrode pattern is prepared by using a maskless laser direct writing technology. Specifically, a negative electron beam resist is spin-coated on the graphene, and is exposed to a pre-designed electrode pattern. Then, the graphene with the electrode pattern is exposed by developing, so that the two-dimensional material insertion layer 3 is formed.

[0056] The insulating tunneling layer 4 with a thickness of 1-2 nm is grown on the two-dimensional material insertion layer 3 by using a radio frequency sputtering process. The target material is MgO, the growth pressure is 0.5 Pa, and the working gas is argon.

[0057] The ferromagnetic metal layer 5 with a thickness of 20-30 nm and the metal protective layer 6 with a thickness of 10-20 nm are grown on the insulating tunneling layer 4 by using a direct current sputtering process. The target materials are CoFeB and Ru, respectively. The growth pressures are 0.5 Pa and 0.6 Pa, respectively. The working gas is argon.

[0058] (5) Reference Figure 1The remaining photoresist is then stripped to obtain a tunnel junction with electrode patterns and a spin-implanted electrode. Specifically, the sample obtained in step 4 is immersed in N-methylpyrrolidone (NMP) stripper for 1–2 hours for stripping. During this process, the remaining photoresist reacts and dissolves with the NMP stripper, causing the sputtered material in the undeveloped areas to peel off, leaving only the electrode patterns. The sample is then removed from the NMP stripper, rinsed with ethanol to remove excess stripper, and dried with nitrogen.

[0059] Example 2

[0060] The difference between Embodiment 2 and Embodiment 1 of this application is that, referring to... Figure 5 A two-dimensional material insertion layer 3 is disposed between the insulating tunneling layer 4 and the ferromagnetic metal layer 5, i.e., above the insulating tunneling layer 4. Due to the weak spin-orbit coupling and interaction between the transition metal atoms and graphene, in-plane magnetic anisotropy is often exhibited. Inserting graphene above the insulating tunneling layer 4 as the two-dimensional material insertion layer 3 allows CoFeB to contact the graphene, causing the CoFeB / graphene system to exhibit in-plane magnetic anisotropy. Therefore, by changing the insertion position of the two-dimensional material insertion layer 3 (above or below the insulating tunneling layer 4), the initial magnetic moment direction of the ferromagnetic metal layer 5 can be controlled, thereby changing the polarization direction of the injected current and controlling the spin luminescence characteristics.

[0061] refer to Figure 6 In a specific embodiment, step 4 specifically includes:

[0062] An insulating tunneling layer 4 of 1-2 nm was grown on the surface of GaN-based quantum light-emitting structure 2 using radio frequency sputtering. The target material was MgO, the growth pressure was 0.5 Pa, and the working gas was argon.

[0063] Graphene bulk sheets are placed on transparent tape and repeatedly adhered and peeled to obtain a few layers of graphene layered sheets.

[0064] The graphene layered sheet is transferred to the surface of the insulating tunneling layer 4. The specific steps are as follows: the graphene layered sheet on the transparent tape is transferred to the insulating tunneling layer 4, and after standing for a period of time, the transparent tape is slowly peeled off, so that the graphene remains on the insulating tunneling layer 4.

[0065] A two-dimensional material insertion layer 3 with electrode shapes is prepared using a maskless laser direct writing technique. The specific steps are as follows: negative electron beam photoresist is spin-coated on graphene, and the graphene with the pre-designed electrode pattern is exposed. Then, it is developed to expose the graphene with the electrode pattern, thus forming the two-dimensional material insertion layer 3.

[0066] The ferromagnetic metal layer 5 of 20-30 nm and the metal protective layer 6 of 10-20 nm are grown on the two-dimensional material insertion layer 3 by a direct current sputtering process, the target materials are CoFeB and Ru respectively, the growth pressure is 0.5 Pa and 0.6 Pa respectively, and the working gas is argon.

[0067] The rest is the same as example one.

[0068] Comparative example

[0069] The difference between the comparative example and examples one and two is that the two-dimensional material insertion layer 3 is not arranged between the light-emitting structure 2 and the insulating tunneling layer 4 or between the insulating tunneling layer 4 and the ferromagnetic metal layer 5 in the GaN-based spin light-emitting device, and the GaN-based spin light-emitting device only comprises the metal substrate 1, the GaN-based quantum light-emitting structure 2, the insulating tunneling layer 4, the ferromagnetic metal layer 5 and the metal protective layer 6 arranged in a stack from top to bottom, and the metal substrate 1 is copper. The rest is the same as examples one and two.

[0070] The GaN-based spin light-emitting device of example one of the present application is placed in an electroluminescence measurement (EL) system, a parallel magnetic field of about 70 mT is applied to regulate the circular polarization ratio of the quantum well light-emitting, and the measured lateral circular polarization electroluminescence spectrum is as shown in Figure 7 The left-handed and right-handed circular polarization spectra both contain two main light-emitting peaks at 450 and 465 nm, respectively from the radiative recombination in the quantum well structure and the defect energy level light-emitting of the material. The device obtains a circular polarization ratio of 6.53% under the positive external magnetic field.

[0071] Under the application of the same parallel magnetic field, the GaN-based spin light-emitting device without the two-dimensional material insertion layer of graphene in the comparative example is taken as a control, and the measured lateral circular polarization electroluminescence spectrum is as shown in Figure 8 The obtained circular polarization ratio is 3.08%, and it can be seen that the performance of the GaN-based spin light-emitting device of the example of the present application is improved.

[0072] The application can make the ferromagnetic metal layer 5 avoid contacting the semiconductor through the pinhole of the insulating tunneling layer 4 by inserting a few-layer uniform smooth graphene as the two-dimensional material insertion layer 3, avoid impedance mismatch, and achieve the purpose of improving the spin injection efficiency. At the same time, because the spin current has a long diffusion length on the graphene, the two-dimensional material insertion layer 3 plays a role in expanding the spin current. At the same time, the two-dimensional material insertion layer 3 is inserted to regulate the ferromagnetic structure: the CoFeB / graphene system is more likely to exhibit in-plane magnetic anisotropy by inserting the two-dimensional material insertion layer 3 above the magnesium oxide; the CoFeB / MgO system is more likely to exhibit perpendicular magnetic anisotropy by inserting the two-dimensional material insertion layer 3 below the magnesium oxide. By changing the insertion position (above or below the insulating tunneling layer 4) of the two-dimensional material insertion layer 3, the initial magnetic moment direction of the ferromagnetic metal layer 5 can be regulated, the polarization direction of the injected current is changed, and the spin light emission characteristics are regulated. By inserting a few-layer two-dimensional material, the quality of the insulating tunneling layer 4 is improved, and the overall performance of the device is improved.

[0073] The above examples are only used to further illustrate the technical solutions of the application, but the application is not limited to the examples, and any simple modification, equivalent change and modification made according to the technical essence of the application to the above examples all fall within the protection scope of the technical solutions of the application.

Claims

1. A GaN-based spin light emitting device, characterized by, The GaN-based spin light-emitting device comprises a metal substrate, a GaN-based quantum light-emitting structure, an insulating tunnel layer, a ferromagnetic metal layer and a metal protective layer which are stacked from top to bottom, the GaN-based quantum light-emitting structure comprises an electron blocking layer, a hole transport layer, a radiative recombination layer and an electron transport layer which are stacked in sequence along the surface of the metal substrate; a two-dimensional material insertion layer is arranged between the insulating tunnel layer and the ferromagnetic metal layer or between the GaN-based quantum light-emitting structure and the insulating tunnel layer, and the preparation method of the GaN-based spin light-emitting device comprises the following steps: 1) growing a GaN buffer layer, an electron transport layer, a radiative recombination layer, a hole transport layer and an electron blocking layer in sequence on a sapphire substrate by a metal organic chemical vapor deposition technology; 2) bonding a metal substrate on the electron blocking layer and stripping the sapphire substrate to expose the GaN buffer layer; 3) thinning the GaN buffer layer and the electron transport layer by an inductively coupled plasma etching technology to obtain a GaN-based quantum light-emitting structure; 4) manufacturing an insulating tunnel layer, a two-dimensional material insertion layer, a ferromagnetic metal layer and a metal protective layer on the surface of the GaN-based quantum light-emitting structure to form a tunnel junction and a spin injection electrode, wherein the insulating tunnel layer, the ferromagnetic metal layer and the metal protective layer are prepared by a magnetron sputtering process, the ferromagnetic metal layer is located above the insulating tunnel layer, and the metal protective layer is located above the ferromagnetic metal layer; the two-dimensional material insertion layer with an electrode pattern is exposed from photoresist by a mechanical stripping process combined with a maskless laser direct writing technology, and the two-dimensional material insertion layer is located between the insulating tunnel layer and the ferromagnetic metal layer or between the GaN-based quantum light-emitting structure and the insulating tunnel layer; 5) stripping the remaining photoresist to obtain a tunnel junction and a spin injection electrode with an electrode pattern; the two-dimensional material insertion layer is 1-3 layers of graphene.

2. The GaN-based spin light emitting device of claim 1, wherein, The electron transport layer is n-type GaN; the radiation recombination layer is In x Ga 1-x N / In y Ga 1-y N quantum well structure; the hole transport layer is p-type GaN; and the electron blocking layer is heavily doped p++ GaN.

3. The GaN-based spin light emitting device of claim 1, wherein, The insulating tunnel layer is MgO with a thickness of 1-2 nm, and the ferromagnetic metal layer is CoFeB or NiFe with a thickness of 20-30 nm.

4. The GaN-based spin light emitting device of claim 1, wherein, The metal protective layer is Ru with a thickness of 10-20 nm.

5. The GaN-based spin light emitting device of claim 1, wherein, The metal substrate is copper.

6. The GaN-based spin light emitting device of claim 1, wherein, The step 4 specifically comprises: repeatedly pasting and stripping a graphene bulk flake on a transparent tape to obtain a graphene layered flake; transferring the graphene layered flake to the surface of the GaN-based quantum light-emitting structure to prepare a two-dimensional material insertion layer with an electrode shape by a maskless laser direct writing technology; growing an insulating tunnel layer with a thickness of 1-2 nm on the two-dimensional material insertion layer by a radio frequency sputtering process, the target material is MgO, the growth pressure is 0.5 Pa, and the working gas is argon; growing a ferromagnetic metal layer with a thickness of 20-30 nm and a metal protective layer with a thickness of 10-20 nm on the insulating tunnel layer by a direct current sputtering process, the target materials are CoFeB and Ru respectively, the growth pressures are 0.5 Pa and 0.6 Pa respectively, and the working gas is argon.

7. The GaN-based spin light emitting device of claim 1, wherein, The step 4 specifically comprises: A 1-2 nm insulating tunnel layer is grown on the surface of the GaN-based quantum light emitting structure by a radio frequency sputtering process, the target material is MgO, the growth pressure is 0.5 Pa, and the working gas is argon; The graphene bulk flake is placed on a transparent tape to be repeatedly pasted and peeled to obtain a graphene layered flake; The graphene layered flake is transferred to the surface of the insulating tunnel layer, and a two-dimensional material insertion layer with an electrode shape is prepared by a maskless laser direct writing technology; A 20-30 nm ferromagnetic metal layer and a 10-20 nm metal protective layer are grown on the two-dimensional material insertion layer by a direct current sputtering process, the target materials are CoFeB and Ru respectively, the growth pressures are 0.5 Pa and 0.6 Pa respectively, and the working gas is argon.

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