Flexible visible light detector based on light field coupling regulation and preparation method and application thereof

Abstract

The invention provides a flexible visible light detector based on light field coupling regulation and a preparation method and application thereof. The flexible visible light detector comprises a flexible substrate layer, a distributed Bragg reflection layer, a current expansion layer, an N-type electrode layer, an N-type diffusion layer, an InGaN / GaN multi-quantum well layer, a P-type diffusion layer and a P-type electrode layer which are sequentially arranged from bottom to top. And the silver nanoparticle layer is positioned on the upper surface of the P-type diffusion layer. Through the design of the periodic InGaN / GaN quantum well structure, the Bragg reflection layer and the silver metal nanoparticle layer, the light responsivity and the light response speed of the visible light detector are improved, so that the visible light detector meets the requirements of a next-generation visible light communication system and the requirements of application scenes such as flexible wearing.

Description

Technical Field

[0001] The present application and invention relate to the field of optoelectronic detection technology, and in particular, to a flexible visible light detector based on optical field coupling regulation, its preparation method and application. Background Art

[0002] With the continuous evolution of the new generation of wireless communication technology, the rich spectral resources contained in the visible light band have enabled visible light communication technology to occupy a key position in the field of the new generation of mobile communication technology. As a semiconductor component that can convert detected optical signals into electrical signals, a visible light detector is one of the core components affecting the performance of the entire visible light communication system.

[0003] The new generation of high-speed visible light communication system has set new standards for the performance of photodetectors. However, currently commercially available Si-based visible light detectors have exposed many problems, such as poor sensitivity in the blue light band, weak radiation resistance of Si materials, and the need to be equipped with a complex filter system, which greatly limits their application scope. Indium gallium nitride (InxGa1-xN, 0 < x < 1) materials have an adjustable bandgap of 0.68 eV to 3.4 eV, can achieve light detection of the entire visible light spectrum, and also have advantages such as good wavelength selectivity, high saturated electron mobility, being a direct bandgap, and a large optical absorption coefficient at the band edge. Therefore, InGaN-based visible light detectors are more suitable for the requirements of high-speed visible light communication systems.

[0004] PIN-type photodetectors have a large built-in electric field. Compared with MSM-type and Schottky-type photodetectors, they have lower dark current and faster optical response speed. However, there is a contradiction between the optical responsivity and the optical response speed in existing PIN-type photodetectors. In the process of improving the optical response speed, such detectors generally face the dilemma of insufficient optical responsivity and are difficult to meet the needs of practical applications. On the other hand, previous InGaN visible light detectors usually use rigid substrates such as sapphire and Si, which cannot be bent, making it impossible to fabricate InGaN-based visible light detectors into flexible devices and severely limiting the application scenarios of the devices.

[0005] Therefore, it is of great significance to develop a PIN-type InGaN-based visible light detector that simultaneously has high optical responsivity and high optical response speed. Summary of the Invention

[0006] The embodiments of the present application provide a flexible visible light detector based on optical field coupling regulation, its preparation method and application to solve the problems existing in the related technologies. The technical solutions are as follows:

[0007] In a first aspect, an embodiment of the present application provides a flexible visible light detector based on optical field coupling regulation, which includes a flexible substrate layer, a distributed Bragg reflection layer, a current spreading layer, an N-type electrode layer, an N-type diffusion layer, an InGaN / GaN multi-quantum well layer, a P-type diffusion layer, and a P-type electrode layer arranged in sequence from bottom to top;

[0008] and a silver nanoparticle layer; the silver nanoparticle layer is located on the upper surface of the P-type diffusion layer.

[0009] In one embodiment, the distributed Bragg reflection layer is composed of a TiO2 layer and a SiO2 layer stacked in sequence.

[0010] In one embodiment, the thickness of the TiO2 layer is 30nm - 100nm, the thickness of the SiO2 layer is 60nm - 100nm, and the period is 6 - 30.

[0011] In one embodiment, the flexible substrate is polyethylene terephthalate or polyethylene naphthalate.

[0012] In one embodiment, the current spreading layer is at least one of ITO, PEDOT:PSS, polypyrrole, and polythiophene.

[0013] In one embodiment, the N-type electrode layer is a Ti / Au alloy.

[0014] In one embodiment, the P-type electrode layer is a Ti / Al / Ni / Au alloy.

[0015] In one embodiment, the N-type diffusion layer is an Si-doped GaN layer, and the doping concentration of Si is 8×10 17 cm -3 -8×10 18 cm -3 .

[0016] In one embodiment, the thickness of the N-type diffusion layer is 50nm - 500nm.

[0017] In one embodiment, the thickness of the InGaN layer in the InGaN / GaN multi-quantum well layer is 2nm - 4nm, and the thickness of the GaN layer is 6nm - 12nm.

[0018] In one embodiment, the InGaN / GaN multi-quantum well layer includes 4 to 18 InGaN layers and 4 to 18 GaN layers.

[0019] In one embodiment, the P-type diffusion layer is an Mg-doped GaN layer, and the doping concentration of Mg is 1×10 18 cm -3 -1×1019 cm -3 。

[0020] In one embodiment, the thickness of the P-type diffusion layer is 50 nm - 300 nm.

[0021] In one embodiment, the silver nanoparticle layer is composed of Ag nanoparticles with a diameter of 20 nm - 50 nm.

[0022] In a second aspect, an embodiment of the present application provides a method for preparing a flexible visible light detector based on optical field coupling regulation, including the following steps:

[0023] Epitaxially grow a buffer layer, an N-type heavily doped GaN etching layer, an N-type diffusion layer, an InGaN / GaN multiple quantum well layer, and a P-type diffusion layer on the polished surface of the substrate in sequence to obtain an epitaxial wafer of the functional layer;

[0024] Deposit a silver metal film on the P-type diffusion layer, and then perform annealing to form a silver nanoparticle layer;

[0025] Deposit an electrode metal on the P-type diffusion layer and perform annealing to achieve ohmic contact to form a P-type metal electrode layer;

[0026] Deposit a Bragg reflector layer on the flexible substrate and prepare a current spreading layer;

[0027] Deposit an N-type metal electrode layer at the periphery on the current spreading layer;

[0028] Etch the N-type heavily doped GaN etching layer in the epitaxial wafer by an electrochemical method to strip the substrate and the buffer layer, and transfer the sample after stripping the substrate and the buffer layer to the flexible substrate with the Bragg reflector layer and the current spreading layer; the N-type diffusion layer is bonded to the current spreading layer.

[0029] In one embodiment, the substrate is a sapphire substrate.

[0030] In one embodiment, the buffer layer is AlN / AlGaN / GaN.

[0031] In one embodiment, the doping concentration of the N-type heavily doped GaN etching layer is 1×10 19 cm -3 -1×10 20 cm -3 ; and the thickness is 2 μm - 3 μm.

[0032] The advantages or beneficial effects in the above technical solutions at least include:

[0033] The flexible visible light detector based on optical field coupling regulation of the present application has a periodic InGaN / GaN quantum well structure, which can improve the problem of poor crystal quality of a relatively thick InGaN thin film with a high In composition; through the design of a Bragg reflector, the transmitted light is reflected back to the absorption layer region to enhance the optical field density of the absorption layer, thereby improving the optical responsivity of the photodetector; on the basis of introducing the Bragg reflector structure, the surface plasmon resonance effect of silver metal nanoparticles is further introduced, which can further effectively enhance the optical field density of the absorption region, increase the number of photo-generated carriers, and improve the optoelectronic coupling efficiency of the photodetector. The flexible visible light detector based on optical field coupling regulation of the present invention has high optical responsivity and fast optical response speed, and can meet the requirements of the next-generation visible light communication system and application scenarios such as flexible wearables.

[0034] The above summary is only for the purpose of the specification and is not intended to be limiting in any way. In addition to the illustrative aspects, embodiments, and features described above, further aspects, embodiments, and features of the present application will be readily apparent by reference to the drawings and the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In the drawings, unless otherwise specified, the same reference numerals throughout the several views refer to the same or similar components or elements. These drawings are not necessarily drawn to scale. It should be understood that these drawings only depict some embodiments disclosed in the present application and should not be regarded as limiting the scope of the present application.

[0036] Figure 1 is a schematic structural diagram of the flexible visible light detector based on optical field coupling regulation of the present invention;

[0037] Among them, 101, flexible substrate; 102, distributed Bragg reflector layer; 103, current spreading layer; 104, N-type diffusion layer; 105, InGaN / GaN multiple quantum well layer; 106, P-type diffusion layer; 107, silver metal nanoparticle layer; 108, P-type metal electrode layer; 109, N-type metal electrode layer;

[0038] Figure 2 is a top view schematic diagram of the flexible visible light detector based on optical field coupling regulation of the present invention;

[0039] Figure 3 is a local scanning electron microscope image of the flexible visible light detector based on optical field coupling regulation, where (a) is the SEM image of the etched thin film in the flexible visible light detector based on optical field coupling regulation; (b) is the SEM image of the silver metal nanoparticle layer in the flexible visible light detector based on optical field coupling regulation;

[0040] Figure 4IV characteristic curves of the flexible visible light detector based on optical field coupling regulation for the example and Comparative Example 1;

[0041] Figure 5 IV characteristic curves of the flexible visible light detector based on optical field coupling regulation for the example and Comparative Example 2;

[0042] Figure 6 Transient optical response curve of the flexible visible light detector based on optical field coupling regulation for the example. Detailed implementation manners

[0043] In the following, only some exemplary embodiments are simply described. As those skilled in the art can recognize, the described embodiments can be modified in various different ways without departing from the spirit or scope of the present application. Therefore, the drawings and the description are considered to be exemplary in nature rather than restrictive.

[0044] Based on enhancing the high responsivity and high response speed of visible light detectors, the present application provides a flexible visible light detector based on optical field coupling regulation, and this flexible photodetector can effectively broaden the application prospect of visible light communication in the field of smart wearables.

[0045] An embodiment of the present application provides a flexible visible light detector based on optical field coupling regulation, which is provided with a flexible substrate layer, a distributed Bragg reflector layer, a current spreading layer, an N-type electrode layer, an N-type diffusion layer, an InGaN / GaN multiple quantum well layer, a P-type diffusion layer, and a P-type electrode layer arranged in sequence from bottom to top;

[0046] And a silver nanoparticle layer; the silver nanoparticle layer is located on the upper surface of the P-type diffusion layer.

[0047] Specifically, using a flexible material as the substrate, a distributed Bragg reflector layer located on the upper surface of the flexible substrate is arranged in sequence; a current spreading layer located on the upper surface of the distributed Bragg reflector layer; an N-type electrode layer located on the upper surface of the current spreading layer; an N-type diffusion layer located on the upper surface of the current spreading layer; an InGaN / GaN multiple quantum well layer located on the upper surface of the N-type diffusion layer; a P-type diffusion layer located on the upper surface of the InGaN / GaN multiple quantum well layer; a P-type electrode layer located on the upper surface of the P-type diffusion layer; a silver nanoparticle layer located on the upper surface of the P-type diffusion layer.

[0048] As one of the implementation manners, the distributed Bragg reflector layer is composed of a TiO2 layer and a SiO2 layer stacked in sequence.

[0049] In the present application, for the light that passes through the absorption layer without being absorbed, the light that leaks out is reflected back to the absorption layer region through the design of the Bragg reflector to enhance the light field density of the absorption layer, thereby improving the light responsivity of the photodetector; on the basis of introducing the Bragg reflector structure, the surface plasmon resonance effect of silver metal nanoparticles is further introduced, and the surface plasmon effect is introduced on the incident light side to enhance the incident light field density, so as to enhance the light field density of the absorption region, increase the number of photo-generated carriers, and improve the optoelectronic coupling efficiency of the photodetector.

[0050] In this embodiment, the thickness of the TiO2 layer is 30 nm - 100 nm, the thickness of the SiO2 layer is 60 nm - 100 nm, and the period is 6 - 30. The thickness of the TiO2 layer is any value between 30 nm - 100 nm, the thickness of the SiO2 layer is any value between 60 nm - 100 nm, and the period is any value between 6 - 30. Preferably, the thickness of the TiO2 layer of the distributed Bragg reflector layer in the present application is 30 - 50 nm, the thickness of the SiO2 layer is 60 - 80 nm, and the period is 10 - 20. Further preferably, the thickness of the TiO2 layer of the distributed Bragg reflector layer is 30 - 40 nm, the thickness of the SiO2 layer is 60 - 70 nm, and the period is 10 - 20. Further preferably, the thickness of the TiO2 layer of the distributed Bragg reflector layer is 36 nm, the thickness of the SiO2 layer is 69 nm, and the period is 15.

[0051] As one of the embodiments, the flexible substrate is polyethylene terephthalate (PET) or polyethylene naphthalate (PEN).

[0052] As one of the embodiments, the current spreading layer is at least one of ITO, PEDOT:PSS, polypyrrole, and polythiophene.

[0053] As one of the embodiments, the N-type electrode layer is a Ti / Au alloy.

[0054] As one of the embodiments, the P-type electrode layer is a Ti / Al / Ni / Au alloy.

[0055] As one of the embodiments, the N-type diffusion layer is an Si-doped GaN layer, and the doping concentration of Si is 8×10 17 cm -3 -8×10 18 cm -3 .

[0056] As one of the embodiments, the thickness of the N-type diffusion layer is 50 nm - 500 nm. The thickness of the N-type diffusion layer is any value between 30 nm - 100 nm.

[0057] As one of the embodiments, the thickness of the InGaN layer in the InGaN / GaN multi-quantum well layer is 2 nm - 4 nm, and the thickness of the GaN layer is 6 nm - 12 nm.

[0058] As one of the embodiments, the InGaN / GaN multi-quantum well layer includes 4 - 18 InGaN layers and 4 - 18 GaN layers.

[0059] It is composed of alternating stacks of InGaN and GaN, and one layer of InGaN and one layer of GaN form a period. In this application, setting the periodic InGaN / GaN multi-quantum well structure can improve the problem of poor crystal quality of the relatively thick InGaN thin film with a high In component.

[0060] As one of the embodiments, the P-type diffusion layer is a Mg-doped GaN layer, and the doping concentration of Mg is 1×10 18 cm -3 -1×10 19 cm -3 .

[0061] As one of the embodiments, the thickness of the P-type diffusion layer is 50 nm - 300 nm.

[0062] As one of the embodiments, the silver nanoparticle layer is composed of Ag nanoparticles with a diameter of 20 nm - 50 nm.

[0063] Introducing the surface plasmon resonance effect of silver metal nanoparticles can further effectively enhance the optical field density in the absorption region, increase the number of photo-generated carriers, and improve the optoelectronic coupling efficiency of the photodetector.

[0064] This application also provides a preparation method of a flexible visible light detector based on optical field coupling regulation, including the following steps:

[0065] Epitaxially grow a buffer layer, an N-type heavily doped GaN etching layer, an N-type diffusion layer, an InGaN / GaN multi-quantum well layer, and a P-type diffusion layer in sequence on the polished surface of the substrate to obtain an epitaxial wafer of the functional layer;

[0066] Deposit a silver metal film on the P-type diffusion layer, and then perform annealing to form a silver nanoparticle layer;

[0067] Deposit an electrode metal on the P-type diffusion layer and perform annealing to achieve ohmic contact to form a P-type metal electrode layer;

[0068] Deposit a Bragg reflection layer on the flexible substrate and prepare a current spreading layer;

[0069] Deposit an N-type metal electrode layer at the periphery of the current spreading layer;

[0070] The N-type heavily doped GaN etching layer in the epitaxial wafer is etched by an electrochemical method to strip the substrate and the buffer layer, and the sample after stripping the substrate and the buffer layer is transferred onto a flexible substrate with a Bragg reflector layer and a current spreading layer; the N-type diffusion layer is bonded to the current spreading layer.

[0071] As one of the implementation manners, the substrate is a sapphire substrate.

[0072] As one of the implementation manners, the buffer layer is AlN / AlGaN / GaN. The buffer layer can be deposited by metal organic chemical vapor deposition (MOCVD) method.

[0073] As one of the implementation manners, the doping concentration of the N-type heavily doped GaN etching layer is 1×10 19 cm -3 -1×10 20 cm -3 ; the thickness is 2 μm - 3 μm. The buffer layer can be deposited by metal organic chemical vapor deposition (MOCVD) method.

[0074] As one of the implementation manners, the silver nanoparticle layer is deposited by photolithography mask and depositing a silver metal film on the P-type diffusion layer by electron beam evaporation. During annealing, the temperature is raised to 450 - 550 °C and then maintained for 15 - 30 min for annealing. Preferably, the temperature is raised to 500 °C at a heating rate of 15 °C / s and then maintained for 20 min for annealing.

[0075] As one of the implementation manners, an electrode metal is deposited on the P-type diffusion layer by mask lithography and annealed to achieve ohmic contact to form a P-type metal electrode layer. Specifically, a bare pattern is formed on the area of the non-silver metal nanoparticle layer on the P-type diffusion layer by mask lithography, and then a Ti layer, an Al layer, a Ni layer and an Au layer with a thickness are sequentially deposited on the P-type diffusion layer by electron beam evaporation. The temperature is raised to 350 - 450 °C and then maintained for 20 - 40 s, and then the temperature is further raised to 750 - 850 °C and maintained for 10 - 20 s to achieve ohmic contact and form a P-type metal electrode layer.

[0076] As one of the implementation manners, the flexible substrate is cleaned before depositing the Bragg reflector layer. In this implementation manner, ultrasonic cleaning is sequentially performed with acetone, isopropyl alcohol and deionized water. The Bragg reflector layer is deposited by electron beam evaporation alternately.

[0077] As one of the implementation manners, the current spreading layer is deposited by electron beam evaporation.

[0078] As one of the implementation manners, the N-type metal electrode layer is also deposited by electron beam evaporation.

[0079] Next, specific embodiments will be used for further illustration.

[0080] Embodiment 1

[0081] A flexible visible light detector based on optical field coupling regulation (the schematic cross-sectional structure is as shown in Figure 1 ; the schematic top view structure is as shown in Figure 2 ), which is composed of a flexible substrate 101, a distributed Bragg reflector layer 102, a current spreading layer 103, an N-type diffusion layer 104, an InGaN / GaN multiple quantum well layer 105, a P-type diffusion layer 106, a silver metal nanoparticle layer 107, a P-type metal electrode layer 108, and an N-type metal electrode layer 109; the substrate 101, the distributed Bragg reflector layer 102, the current spreading layer 103, the N-type diffusion layer 104, the InGaN / GaN multiple quantum well layer 105, the P-type diffusion layer 106, and the silver metal nanoparticle layer 107 are stacked in sequence; the InGaN / GaN multiple quantum well layer 105 is composed of multiple InGaN layers and multiple GaN layers alternately stacked; the P-type metal electrode layer 108 is disposed on the side of the P-type diffusion layer 106 away from the InGaN / GaN multiple quantum well layer 105; the N-type metal electrode layer 109 is disposed on the side where the current spreading layer 103 contacts the N-type diffusion layer 104 and does not contact the N-type diffusion layer 104;

[0082] The preparation method of the above flexible visible light detector based on optical field coupling regulation is as follows:

[0083] 1) Ultrasonically clean a sapphire substrate (wafer, 2 inches in diameter) with acetone, isopropyl alcohol, and deionized water for 10 minutes each in sequence, and then epitaxially grow a buffer layer, an etching layer, an N-type diffusion layer, an InGaN / GaN multiple quantum well layer, and a P-type diffusion layer on one side of the sapphire substrate by metalorganic chemical vapor deposition (MOCVD) method. The buffer layer is an AlN / AlGaN / GaN layer; the etching layer is an Si-doped GaN layer with an Si doping concentration of 5×10 19 cm -3 , with a thickness of 2 μm; the N-type diffusion layer is an Si-doped GaN layer with an Si doping concentration of 3×10 18 cm -3 , the thickness of the N-type diffusion layer is 200 nm, the InGaN / GaN multiple quantum well layer is composed of 8 InGaN layers with a thickness of 2.5 nm and 8 GaN layers with a thickness of 10 nm alternately stacked, the P-type diffusion layer is an Mg-doped GaN layer with an Mg doping concentration of 5×10 18 cm -3 , and the thickness of the P-type diffusion layer is 150 nm;

[0084] 2) Several bare patterns of the same size are formed on the P-type diffusion layer through mask lithography. Then, an Ag film with a thickness of 8 nm is deposited on the dielectric layer by electron beam evaporation. After that, the temperature is raised to 500 °C at a heating rate of 15 °C / s and kept for 20 min for annealing to form a silver metal nanoparticle layer;

[0085] 3) Bare patterns are formed on the area of the P-type diffusion layer that is not the silver metal nanoparticle layer through mask lithography. Then, a Ti layer with a thickness of 30 nm, an Al layer with a thickness of 120 nm, a Ni layer with a thickness of 60 nm, and an Au layer with a thickness of 60 nm are sequentially deposited on the P-type diffusion layer by electron beam evaporation. After that, the temperature is raised to 400 °C at a heating rate of 15 °C / s and kept for 30 s, and then the temperature is continuously raised to 800 °C at a heating rate of 15 °C / s and kept for 15 s to achieve ohmic contact, forming a P-type metal electrode layer;

[0086] 4) The PET flexible substrate is ultrasonically cleaned with acetone, isopropyl alcohol, and deionized water for 10 min each in sequence. Then, a TiO2 layer with a thickness of 36 nm and a SiO2 layer with a thickness of 69 nm are alternately deposited by electron beam evaporation for 15 cycles. After that, a 200-nm-thick ITO conductive layer is alternately deposited by electron beam evaporation. Finally, a Ti layer with a thickness of 60 nm and an Au layer with a thickness of 120 nm are deposited by electron beam evaporation around the ITO of the PET / ITO carrier;

[0087] 5) The N-type GaN etching layer is etched by an electrochemical method to strip the substrate and buffer layer. The etching solution is oxalic acid with a concentration of 0.3 mol / L, the applied bias range is 20 V, and the etching time is 30 min. After etching, the substrate and buffer layer can be stripped, and the obtained sample is transferred to a carrier with a Bragg reflector layer and a conductive layer to obtain the flexible visible light detector based on optical field coupling regulation.

[0088] Comparative Example 1

[0089] A flexible visible light detector based on optical field coupling regulation, which is different from Example 1 in that, except for not containing a metal nanoparticle layer and a Bragg reflector layer, the rest is exactly the same as the flexible visible light detector based on optical field coupling regulation in Example 1.

[0090] Comparative Example 2

[0091] A flexible visible light detector based on optical field coupling regulation, which is different from Example 1 in that, except for not containing a metal nanoparticle layer, the rest is exactly the same as the flexible visible light detector based on optical field coupling regulation in Example 1.

[0092] Material characterization and performance testing:

[0093] 1) The thin film structure obtained by electrochemically etching the flexible visible light detector based on optical field coupling regulation in the embodiment was observed by scanning electron microscopy, and the SEM image is as shown in Figure 3 (a);

[0094] The silver metal nanoparticle layer prepared by annealing was observed by scanning electron microscopy, and the SEM image is as shown in Figure 3 (b).

[0095] It can be seen from Figure 3 that: it can be observed that the substrate and buffer layer structures are well peeled off, and an InGaN / GaN MQW thin film with high integrity is obtained. Through SEM, it can also be seen that the silver metal nanoparticles are evenly distributed, and the main diameters of the silver metal nanoparticles are distributed in the range of 20 - 50 nm.

[0096] 2) The optoelectronic properties of the flexible visible light detector based on optical field coupling regulation in the embodiment and Comparative Example 1 were tested, and the IV characteristic curve diagram is as shown in Figure 4 .

[0097] It can be seen from Figure 4 that: due to the fact that metal nanoparticles can induce the surface plasmon polariton effect, the Bragg reflector can reflect the light passing through the absorption layer back, thereby enhancing the photocurrent response of the visible light detector regulated by optical field coupling.

[0098] 3) The optoelectronic properties of the flexible visible light detector based on optical field coupling regulation in the embodiment and Comparative Example 2 were tested, and the IV characteristic curve diagram is as shown in Figure 5 .

[0099] It can be seen from Figure 5 that: when only the Bragg reflector is introduced, the photocurrent response of the device also increases significantly. Combining with the Figure 4 data, it can be proved that the improvement of the optical field density in the absorption layer of the visible light detector regulated by optical field coupling is due to the coupling effect of silver metal nanoparticles and the Bragg reflector.

[0100] 4) The transient photocurrent response characteristics of the flexible visible light detector based on optical field coupling regulation in the embodiment were tested, and the results are as shown in Figure 6 .

[0101] It can be seen from Figure 6 that: the flexible visible light detector based on optical field coupling regulation has a fast photocurrent response speed, and the photocurrent response rise / fall times reach 36 μs / 6 μs respectively.

[0102] In summary, the present invention discloses a distributed Bragg reflector layer on the upper surface of a flexible substrate for a flexible visible light detector based on optical field coupling regulation; a current spreading layer is distributed on the upper surface of the distributed Bragg reflector layer; an N-type electrode layer is distributed on the upper surface of the current spreading layer; an N-type diffusion layer is distributed on the upper surface of the current spreading layer; an InGaN / GaN multiple quantum well layer is distributed on the upper surface of the N-type diffusion layer; and a P-type diffusion layer on the upper surface of the periodic InGaN / GaN multiple quantum well layer; a P-type electrode layer on the upper surface of the P-type diffusion layer; and a silver nanoparticle layer is simultaneously distributed on the upper surface of the P-type diffusion layer; so that the flexible visible light detector based on optical field coupling regulation of the present invention has high responsivity and high response speed, and the flexible photodetector can effectively broaden the application prospect of visible light communication in the field of intelligent wearables.

[0103] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples", etc. means that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. Moreover, the specific features, structures, materials, or characteristics described may be combined in a suitable manner in any one or more embodiments or examples. In addition, without contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples.

[0104] In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present application, "a plurality" means two or more unless otherwise specifically defined.

[0105] The above is only the specific implementation manner of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art within the technical scope disclosed in the present application can easily think of various changes or substitutions, and these should all be covered by the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A flexible visible light detector based on light field coupling control, characterized in that: A flexible substrate layer, a distributed Bragg reflection layer, a current spreading layer, an N-type electrode layer, an N-type diffusion layer, an InGaN / GaN multi-quantum well layer, a P-type diffusion layer and a P-type electrode layer are sequentially arranged from bottom to top; and a silver nanoparticle layer; the silver nanoparticle layer is located on the upper surface of the P-type diffusion layer.

2. According to claim 1, a flexible visible light detector based on light field coupling control is characterized in that: The distributed Bragg reflection layer is composed of a TiO2 layer and a SiO2 layer stacked in sequence; the thickness of the TiO2 layer is 30nm-100nm, the thickness of the SiO2 layer is 60nm-100nm, and the period is 6-30.

3. The flexible visible light detector based on light field coupling control according to claim 1, characterized in that: The flexible substrate is polyethylene terephthalate or polyethylene naphthalate; The current spreading layer is at least one of ITO, PEDOT:PSS, polypyrrole and polythiophene.

4. The flexible visible light detector based on light field coupling control according to claim 1, characterized in that: The N-type electrode layer is a Ti / Au alloy; The P-type electrode layer is Ti / Al / Ni / Au alloy.

5. The flexible visible light detector based on light field coupling control according to claim 1, characterized in that: The N-type diffusion layer is a Si-doped GaN layer, and the Si doping concentration is 8×10 17 cm -3 -8×10 18 cm -3 ; The thickness of the N-type diffusion layer is 50nm-500nm.

6. The flexible visible light detector based on light field coupling control according to claim 1, characterized in that: The thickness of the InGaN layer in the InGaN / GaN multi-quantum well layer is 2nm-4nm, and the thickness of the GaN layer is 6nm-12nm; The InGaN / GaN multi-quantum well layer includes 4 to 18 InGaN layers and 4 to 18 GaN layers.

7. The flexible visible light detector based on light field coupling control according to claim 1, characterized in that: The P-type diffusion layer is a Mg-doped GaN layer, and the Mg doping concentration is 1×10 18 cm -3 -1×10 19 cm -3 ; The thickness of the P-type diffusion layer is 50nm-300nm.

8. The flexible visible light detector based on light field coupling control according to claim 1, characterized in that: The silver nanoparticle layer is composed of Ag nanoparticles with a diameter of 20nm-50nm.

9. A method for preparing a flexible visible light detector based on light field coupling control according to any one of claims 1 to 8, characterized in that: The following steps are involved: Epitaxially growing a buffer layer, an N-type heavily doped GaN etching layer, an N-type diffusion layer, an InGaN / GaN multi-quantum well layer and a P-type diffusion layer on the polished surface of the substrate in sequence to obtain an epitaxial wafer of a functional layer; Depositing a silver metal film on the P-type diffusion layer and then annealing to form a silver nanoparticle layer; Depositing electrode metal on the P-type diffusion layer and performing annealing to achieve ohmic contact to form a P-type metal electrode layer; Depositing a Bragg reflection layer on a flexible substrate and preparing a current spreading layer; Depositing an N-type metal electrode layer on the periphery of the current spreading layer; The N-type heavily doped GaN etching layer in the epitaxial wafer is etched by electrochemical method to peel off the substrate and buffer layer, and the sample after peeling off the substrate and buffer layer is transferred to a flexible substrate with a Bragg reflection layer and a current spreading layer; the N-type diffusion layer is bonded to the current spreading layer.

10. The method for preparing a flexible visible light detector based on light field coupling control according to claim 9, characterized in that: The substrate is a sapphire substrate; the buffer layer is AlN / AlGaN / GaN; The doping concentration of the N-type heavily doped GaN etching layer is 1×10 19 cm -3 -1×10 20 cm -3 ; Thickness is 2μm-3μm.

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