A flexible visible light detector and a preparation method and application thereof

Abstract

The application 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, from bottom to top, 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, and a silver nanoparticle layer located on the upper surface of the P-type diffusion layer. Through the InGaN / GaN quantum well structure with periodicity, the design of 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 the next-generation visible light communication system and the requirements of application scenarios such as flexible wearing.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of photoelectric detection, and in particular to a flexible visible light detector based on light field coupling regulation and a preparation method and application thereof. BACKGROUND

[0002] With the continuous evolution of new generation wireless communication technology, the rich spectrum resources contained in the visible light band make visible light communication technology occupy a key position in the field of new generation mobile communication technology. As a kind of semiconductor element that can convert the detected optical signal into an electrical signal, the visible light detector is one of the core components that affect the performance of the entire visible light communication system.

[0003] The new generation of high-speed visible light communication system sets new standards for the performance of photoelectric detectors. However, the current commercial Si-based visible light detector has many problems, such as poor sensitivity in the blue light band, weak radiation resistance of Si material, and the need to equip a complex optical filtering system, which greatly limits its application range. Indium gallium nitride (InxGa1-xN, 0 < x < 1) material has an adjustable band gap of 0.68eV to 3.4eV, which can realize light detection of the entire visible light spectrum, and also has the advantages of good wavelength selectivity, high saturated electron mobility, direct band gap, and large band edge light absorption coefficient. Therefore, the InGaN-based visible light detector is more suitable for the needs of the high-speed visible light communication system.

[0004] PIN-type photoelectric detectors have a large built-in electric field, and compared with MSM-type and Schottky-type photoelectric detectors, they have lower dark current and faster light response speed. However, the existing PIN-type photoelectric detectors have a contradiction between light response degree and light response speed. In the process of improving the light response speed, such detectors generally face the dilemma of insufficient light response degree, which is difficult to meet the needs of practical applications. On the other hand, the existing InGaN visible light detector usually uses a rigid substrate such as sapphire or Si, which cannot be bent, which makes it impossible to prepare InGaN-based visible light detectors into flexible devices, 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 with high light response degree and high light response speed. SUMMARY

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

[0007] In a first aspect, the embodiments of the present application provide a flexible visible light detector based on light field coupling regulation, which comprises, from bottom to top, 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.

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

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

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

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

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

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

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

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

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

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

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

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

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

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

[0022] In a second aspect, the embodiments of the present application provide a preparation method of a flexible visible light detector based on light field coupling regulation, comprising the following steps:

[0023] 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 are successively epitaxially grown on a polished surface of a substrate to obtain an epitaxial wafer of a functional layer;

[0024] A silver metal film is deposited on the P-type diffusion layer, and then annealing is performed to form a silver nanoparticle layer;

[0025] An electrode metal is deposited on the P-type diffusion layer, and annealing is performed to realize ohmic contact and form a P-type metal electrode layer;

[0026] A Bragg reflection layer is deposited on a flexible substrate, and a current spreading layer is prepared;

[0027] An N-type metal electrode layer is deposited on the periphery of the current spreading layer;

[0028] An electrochemical method is used to etch the N-type heavily doped GaN etching layer in the epitaxial wafer to separate the substrate and the buffer layer, and the sample after separating the substrate and the buffer layer is transferred to the flexible substrate with the Bragg reflection layer and the current spreading layer; the N-type diffusion layer is bonded to the current spreading layer.

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

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

[0031] In an embodiment, the N-type heavily doped GaN etching layer has a doping concentration of 1x1019-1x1021cm-3. 19 cm -3 -1x1019cm-3. 20 cm -3 ; and a thickness of 2-3 μm.

[0032] The above technical solution has at least the following advantages or beneficial effects:

[0033] The flexible visible light detector based on light field coupling regulation of the application has a periodic InGaN / GaN quantum well structure, which can improve the problem of poor crystal quality of a relatively thick high-In component InGaN film; the design of the Bragg reflector is used to reflect the transmitted light back to the absorption layer area to achieve the purpose of enhancing 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 introduced, which can further effectively improve the light field density of the absorption area, increase the number of photo-generated carriers, and improve the photoelectric coupling efficiency of the photodetector. The flexible visible light detector based on light field coupling regulation of the application has high light responsivity and fast light response speed, and can meet the needs of the next generation of visible light communication systems and the needs of flexible wearable application scenarios.

[0034] The above summary is intended to illustrate only and is not intended to limit the application in any way. Further aspects, implementations, and features of the application will be apparent from a review of the drawings and the following detailed description. BRIEF DESCRIPTION OF DRAWINGS

[0035] In the drawings, like reference numerals refer to same or similar components throughout the several views. The drawings are not necessarily to scale. It should be understood that the drawings only depict some embodiments in accordance with the disclosure and should not be considered limiting of the scope of the disclosure.

[0036] Figure 1 Structure schematic diagram of the flexible visible light detector based on light field coupling regulation of the application;

[0037] Wherein, 101, flexible substrate; 102, distributed Bragg reflector layer; 103, current spreading layer; 104, N-type diffusion layer; 105, InGaN / GaN multi-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 Structure schematic diagram of the flexible visible light detector based on light field coupling regulation of the application;

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

[0040] Figure 4IV characteristic curve of the flexible visible light detector based on light field coupling regulation of the example and comparative example 1;

[0041] Figure 5 IV characteristic curve of the flexible visible light detector based on light field coupling regulation of the example and comparative example 2;

[0042] Figure 6 Transient light response curve of the flexible visible light detector based on light field coupling regulation of the example. DETAILED DESCRIPTION

[0043] Hereinafter, only certain example embodiments are simply described. As can be appreciated by those skilled in the art, 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 description are to be regarded as illustrative in nature rather than restrictive.

[0044] Based on the high responsivity and high response speed of the enhanced visible light detector, the present application provides a flexible visible light detector based on light field coupling regulation, which can effectively widen the application prospect of visible light communication in the field of smart wear.

[0045] The example of the present application provides a flexible visible light detector based on light field coupling regulation, which is sequentially provided from bottom to top with 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.

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

[0047] Specifically, a flexible material is used as a substrate, and sequentially provided are a distributed Bragg reflection layer on the upper surface of the flexible substrate, a current expansion layer on the upper surface of the distributed Bragg reflection layer, an N-type electrode layer on the upper surface of the current expansion layer, an N-type diffusion layer on the upper surface of the current expansion layer, an InGaN / GaN multi-quantum well layer on the upper surface of the N-type diffusion layer, a P-type diffusion layer on the upper surface of the InGaN / GaN multi-quantum well layer, a P-type electrode layer on the upper surface of the P-type diffusion layer, and a silver nanoparticle layer on the upper surface of the P-type diffusion layer.

[0048] As one of the embodiments, the distributed Bragg reflection layer is sequentially stacked by a TiO2 layer and a SiO2 layer.

[0049] The present application is aimed at the light which is not absorbed through the absorption layer, and the light is reflected back to the absorption layer region by the design of the Bragg mirror to enhance the light field density of the absorption layer, so as to improve the light responsivity of the photodetector; on the basis of introducing the Bragg mirror structure, the surface plasmon resonance effect of silver metal nanoparticles is introduced, the surface plasmon effect is introduced on the side of the incident light 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 photoelectric coupling efficiency of the photodetector.

[0050] In the embodiment, the thickness of the TiO2 layer is 30-100 nm, the thickness of the SiO2 layer is 60-100 nm, and the period is 6-30. The thickness of the TiO2 layer is any value between 30-100 nm, the thickness of the SiO2 layer is any value between 60-100 nm, and the period is any value between 6-30. Preferably, the thickness of the TiO2 layer of the distributed Bragg reflector 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 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 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 Ti / Au alloy.

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

[0055] As one of the embodiments, the N-type diffusion layer is a 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 50-500 nm. The thickness of the N-type diffusion layer is any value between 30-100 nm.

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

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

[0059] Wherein, the InGaN and GaN are alternately stacked, and one layer of InGaN and one layer of GaN form a period. In the present application, the periodic InGaN / GaN multi-quantum well structure can improve the problem of poor crystal quality of a relatively thick high-In-content InGaN thin film.

[0060] As one of the embodiments, the P-type diffusion layer is a Mg-doped GaN layer, and the doping concentration of Mg is 1×1018-1×1021 cm-3. 18 cm -3 -1×10 19 cm -3 .

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

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

[0063] The surface plasmon resonance effect of silver metal nanoparticles is introduced, which can further effectively improve the light field density of the absorption region, increase the number of photo-generated carriers, and improve the photoelectric coupling efficiency of the photodetector.

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

[0065] 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 are successively epitaxially grown on the polished surface of the substrate to obtain an epitaxial wafer of the functional layer;

[0066] A silver metal film is deposited on the P-type diffusion layer, and then annealing is performed to form a silver nanoparticle layer;

[0067] An electrode metal is deposited on the P-type diffusion layer, and annealing is performed to realize ohmic contact and form a P-type metal electrode layer;

[0068] A Bragg reflection layer is deposited on the flexible substrate, and a current spreading layer is prepared;

[0069] An N-type metal electrode layer is deposited on the periphery of the current spreading layer;

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

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

[0072] As one of the embodiments, 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 embodiments, the N-type heavily doped GaN etching layer has a doping concentration of 1×1018cm-3. 19 cm-3. -3 1×1018cm-3. 20 cm-3. -3 The thickness is 2-3 μm. The buffer layer can be deposited by metal organic chemical vapor deposition (MOCVD) method.

[0074] As one of the embodiments, the silver nanoparticle layer is deposited by electron beam evaporation method through photolithography mask and on the P-type diffusion layer. During annealing, the temperature is raised to 450-550 °C and kept for 15-30 min for annealing. Preferably, the temperature is raised to 500 °C at a rate of 15 °C / s and kept for 20 min for annealing.

[0075] As one of the embodiments, the electrode metal is deposited on the P-type diffusion layer by mask photolithography, and annealing is performed to achieve ohmic contact, forming a P-type metal electrode layer. Specifically, a bare pattern is formed on the P-type diffusion layer on the non-silver metal nanoparticle layer area by mask photolithography, and then Ti layer, Al layer, Ni layer and Au layer are sequentially deposited on the P-type diffusion layer by electron beam evaporation, the temperature is raised to 350-450 °C and kept for 20-40 s, and then the temperature is continuously raised to 750-850 °C and kept for 10-20 s to achieve ohmic contact, forming a P-type metal electrode layer.

[0076] As one of the embodiments, the flexible substrate is cleaned before depositing the Bragg reflection layer. In this embodiment, ultrasonic cleaning is performed with acetone, isopropyl alcohol and deionized water in sequence. The Bragg reflection layer is deposited by electron beam evaporation alternately.

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

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

[0079] Further illustration is made below with specific examples.

[0080] Example 1

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

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

[0083] 1) The sapphire substrate (wafer, diameter 2 inches) is sequentially cleaned with acetone, isopropyl alcohol, and deionized water for 10 min each, and then a buffer layer, an etching layer, an N-type diffusion layer, an InGaN / GaN multi-quantum well layer, and a P-type diffusion layer are sequentially epitaxially grown on one side of the sapphire substrate by metal organic chemical vapor deposition (MOCVD) method; the buffer layer is an AlN / AlGaN / GaN layer; the etching layer is a Si-doped GaN layer with a Si doping concentration of 5×10 19 cm -3 -2 and a thickness of 2 μm; the N-type diffusion layer is a Si-doped GaN layer with a Si doping concentration of 3×10 18 cm -3 -3 and a thickness of 200 nm; the InGaN / GaN multi-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 a Mg-doped GaN layer with a Mg doping concentration of 5×10 18 cm -3 -2 and a thickness of 150 nm;

[0084] 2) Forming several exposed patterns with the same size on the P-type diffusion layer by mask photolithography, then depositing a 8 nm-thick Ag film on the dielectric layer by electron beam evaporation, and then annealing at 500℃ for 20 min after heating at a rate of 15℃ / s to form a silver metal nanoparticle layer;

[0085] 3) Forming exposed patterns on the non-silver metal nanoparticle layer region of the P-type diffusion layer by mask photolithography, then depositing a 30 nm-thick Ti layer, a 120 nm-thick Al layer, a 60 nm-thick Ni layer and a 60 nm-thick Au layer on the P-type diffusion layer in turn by electron beam evaporation, and then realizing ohmic contact by heating at a rate of 15℃ / s to 400℃ for 30 s and then continuing to heat at a rate of 15℃ / s to 800℃ for 15 s to form a P-type metal electrode layer;

[0086] 4) Ultrasonic cleaning the PET flexible substrate with acetone, isopropyl alcohol and deionized water for 10 min in turn, and then alternately depositing a 36 nm-thick TiO2 layer and a 69 nm-thick SiO2 layer for 15 cycles by electron beam evaporation, and then alternately depositing a 200 nm-thick ITO conductive layer by electron beam evaporation, and finally depositing a 60 nm-thick Ti and a 120 nm-thick Au around the ITO of the PET / ITO carrier by electron beam evaporation;

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

[0088] Comparative Example 1

[0089] A flexible visible light detector based on light field coupling regulation, which is completely same as the visible light detector based on light field coupling regulation of Example 1 except that it does not contain a metal nanoparticle layer and a Bragg mirror layer.

[0090] Comparative Example 2

[0091] A flexible visible light detector based on light field coupling regulation, which is completely same as the visible light detector based on light field coupling regulation of Example 1 except that it does not contain a metal nanoparticle layer.

[0092] Material characterization and performance test:

[0093] 1) The thin film structure of the flexible visible light detector based on light field coupling regulation of the embodiment was subjected to electrochemical etching for scanning electron microscope observation, and the SEM image is shown in FIG. 8(a); Figure 3

[0094] The annealed silver metal nanoparticle layer was subjected to scanning electron microscope observation, and the SEM image is shown in FIG. 8(b). Figure 3

[0095] It can be known from FIG. 8 that the substrate and buffer layer structure can be well peeled off, and the InGaN / GaN MQW film with high integrity can be obtained. The silver metal nanoparticles are uniformly distributed, and the main diameter of the silver metal nanoparticles is distributed in the range of 20-50 nm. Figure 3

[0096] 2) The photoelectric performance of the flexible visible light detector based on light field coupling regulation of the embodiment and Comparative Example 1 was tested, and the IV characteristic curve is shown in FIG. 9. Figure 4

[0097] It can be known from FIG. 9 that due to the surface plasmon effect induced by the metal nanoparticles and the reflection of the light penetrating through the absorption layer back by the Bragg reflector, the light response current of the visible light detector based on light field coupling regulation can be enhanced. Figure 4

[0098] 3) The photoelectric performance of the flexible visible light detector based on light field coupling regulation of the embodiment and Comparative Example 2 was tested, and the IV characteristic curve is shown in FIG. 10. Figure 5

[0099] It can be known from FIG. 10 that when only the Bragg reflector is introduced, the light response current of the device is also obviously improved, and the data of FIG. 9 can prove that the improvement of the light field density of the absorption layer in the visible light detector based on light field coupling regulation is due to the coupling effect of the silver metal nanoparticles and the Bragg reflector. Figure 5 Figure 4

[0100] 4) The transient light response characteristics of the flexible visible light detector based on light field coupling regulation of the embodiment were tested, and the results are shown in FIG. 11. Figure 6

[0101] It can be known from FIG. 11 that the flexible visible light detector based on light field coupling regulation has a fast light response speed, and the light response rise / fall time reaches 36 μs / 6 μs. Figure 6

[0102] ​​​​​​​​​​In summary, the application discloses a distributed Bragg reflector layer on the surface of a flexible substrate of a flexible visible light detector based on light field coupling regulation, a current spreading layer distributed on the surface of the distributed Bragg reflector layer, an N-type electrode layer distributed on the surface of the current spreading layer, an N-type diffusion layer distributed on the surface of the current spreading layer, an InGaN / GaN multi-quantum well layer distributed on the surface of the N-type diffusion layer, a P-type diffusion layer on the surface of the periodic InGaN / GaN multi-quantum well layer, a P-type electrode layer on the surface of the P-type diffusion layer, and a silver nanoparticle layer distributed on the surface of the P-type diffusion layer, so that the flexible visible light detector based on light field coupling regulation has high responsivity and high response speed, and the flexible photoelectric detector can effectively widen the application prospect of visible light communication in the field of smart wear.

[0103] In the description of the present specification, the description of the terms "one embodiment", "some embodiments", "an example", "a specific example", or "some examples" 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 can be combined in any appropriate manner in any one or more embodiments or examples. In addition, different embodiments or examples described in the present specification and the features of different embodiments or examples can be combined and combined by those skilled in the art without contradiction.

[0104] In addition, the terms "first", "second" are only for the purpose of description, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of indicated technical features. Therefore, the features defined with "first", "second" can explicitly or implicitly include at least one feature. In the description of the present application, the meaning of "multiple" is two or more, unless otherwise specifically limited.

[0105] The above is only a specific embodiment of the present application, but the protection scope of the present application is not limited thereto, and any skilled person in the art can easily think of various changes or replacements within the technical range disclosed by the present application, which should be covered within 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, characterized in that, 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 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 metal nanoparticle layer; the silver metal nanoparticle layer is located on the upper surface of the P-type diffusion layer; the silver metal nanoparticle layer is composed of Ag nanoparticles with a diameter of 20-50 nm; the distributed Bragg reflector layer is composed of TiO2 layers and SiO2 layers which are sequentially stacked; the thickness of the TiO2 layer is 30-100 nm, the thickness of the SiO2 layer is 60-100 nm, and the period is 6-30; The N-type diffusion layer is a Si-doped GaN layer, the doping concentration of Si is 8x10 17 cm -3 -8x10 18 cm -3 ; the thickness of the N-type diffusion layer is 50-500 nm; the thickness of the InGaN layer in the InGaN / GaN multi-quantum well layer is 2-4 nm, and the thickness of the GaN layer is 6-12 nm; the InGaN / GaN multi-quantum well layer contains 4-18 InGaN layers and 4-18 GaN layers.

2. The flexible visible light detector according to claim 1, wherein the flexible substrate is polyethylene terephthalate or polyethylene naphthalate; the current spreading layer is at least one of ITO, PEDOT:PSS, polypyrrole and polythiophene.

3. The flexible visible light detector according to claim 1, wherein the N-type electrode layer is Ti / Au alloy; the P-type electrode layer is Ti / Al / Ni / Au alloy.

4. The flexible visible light detector according to claim 1, wherein The P-type diffusion layer is a Mg-doped GaN layer, the doping concentration of Mg is 1 x 10 18 cm -3 -1 x 10 19 cm -3 ; the thickness of the P-type diffusion layer is 50-300 nm.

5. A method of producing a flexible visible light detector according to any one of claims 1 to 4, characterized in that comprising the following steps: 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 are sequentially epitaxially grown on the polished surface of the substrate to obtain an epitaxial wafer of functional layers; a silver metal film is deposited on the P-type diffusion layer, and then annealing is performed to form a silver metal nanoparticle layer; an electrode metal is deposited on the P-type diffusion layer, and annealing is performed to realize ohmic contact and form a P-type metal electrode layer; a Bragg reflector layer is deposited on the flexible substrate, and a current spreading layer is prepared; an N-type metal electrode layer is deposited on the periphery of the current spreading layer; the N-type heavily doped GaN etching layer in the epitaxial wafer is etched by an electrochemical method to separate the substrate and the buffer layer, and the sample after separating the substrate and the buffer layer is transferred 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.

6. The preparation method of the flexible visible light detector according to claim 5, wherein the substrate is a sapphire substrate; and the buffer layer is AlN / AlGaN / GaN. The N-type heavily doped GaN etching layer has a doping concentration of 1 x 1019 19 cm -3 -1 x 1018 20 cm -3 ; and a thickness of 2 μm-3 μm.

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