A photomultiplier type detector and method of manufacture

Abstract

The application relates to the field of photoelectric detectors, in particular to a photomultiplier type detector and a preparation method, which comprises an anode substrate, a cathode substrate and a separator, the anode substrate and the cathode substrate are arranged in parallel opposition, the surfaces of the anode substrate and the cathode substrate are provided with photoconductive layers, the photoconductive layers are in a vacuum state, and the photoconductive layers are all in sharp cone structures. The application realizes collision ionization of high-energy electrons and photoconductor and photoelectric multiplication effect by utilizing the scattering-free characteristics of electron transportation in the vacuum. On the other hand, the nano sharp cone structure photoconductive layer is utilized to regulate electric field distribution and specific surface area, improve electron transportation efficiency and charge collection efficiency, so that a large-area, high-sensitivity, low-dark-current, fast-response and long-life photoelectric detector is realized.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of photodetectors, and more particularly, to a photomultiplier detector and a preparation method. BACKGROUND

[0002] As a high-performance photoelectric conversion device, photomultiplier detectors have shown great potential for application in various high-tech fields, especially in critical areas such as night vision imaging, space exploration, medical imaging, and high-energy physics experiments. These fields have very high requirements for key performance indicators such as sensitivity, dark current, response speed, and lifetime of the detector.

[0003] In terms of improving the photocurrent and sensitivity of photodetectors, avalanche effect has been proven to be a very effective approach. Avalanche photodiodes are a typical application of this principle. By applying a high electric field inside the device, photo-generated carriers will undergo avalanche multiplication effect under the action of the electric field, thereby greatly enhancing the photocurrent and achieving high-sensitivity photodetection. However, despite the excellent performance of avalanche photodiodes in terms of sensitivity, they also face some challenges. For example, avalanche photodiodes are sensitive to temperature and have high dark current, especially under high-voltage working conditions, which can easily lead to thermal runaway, affecting the long-term stability and reliability of the device.

[0004] To overcome the limitations of avalanche photodiodes, researchers have been exploring new materials and structures in order to achieve lower dark current and higher sensitivity photodetection. Among them, a new type of photomultiplier detector based on avalanche effect has emerged. This detector successfully reduces the dark current by optimizing the electric field distribution and material selection while maintaining high sensitivity. However, despite these advances, the current photomultiplier detectors are still very demanding in terms of material selection and difficult to achieve large-area imaging device preparation, which limits the application range of photomultiplier detectors in certain fields. SUMMARY

[0005] The present application provides a photomultiplier detector and a preparation method to overcome at least one of the deficiencies of the prior art.

[0006] The present application aims to at least partially solve the above technical problems.

[0007] To solve the above technical problems, the technical solution of the present application is as follows:

[0008] A photomultiplier detector, comprising an anode substrate, a cathode substrate and a separator, the anode substrate and the cathode substrate are arranged in parallel, the surfaces of the anode substrate and the cathode substrate are provided with photoconductive layers, the anode substrate and the cathode substrate are fixedly connected through the separator, the photoconductive layers are in a vacuum state, and the photoconductive layers are all in a sharp cone structure.

[0009] Further, the photoconductive layer comprises a plurality of semiconductor nano-cone structures and a photoconductor film arranged on the semiconductor.

[0010] Further, the photoconductive layer comprises a first photoconductive layer arranged on the anode substrate and a second photoconductive layer arranged on the cathode substrate, the first photoconductive layer comprises a plurality of first semiconductor nano-cone structures and a first photoconductor film arranged on the first semiconductor, and the second photoconductive layer comprises a plurality of second semiconductor nano-cone structures and a second photoconductor film arranged on the second semiconductor.

[0011] Further, the anode substrate comprises an anode substrate and an anode electrode, the anode electrode is arranged on the anode substrate, and the surface of the anode electrode is provided with the first photoconductive layer.

[0012] Further, the cathode substrate comprises a cathode substrate and a cathode electrode, the cathode electrode is arranged on the cathode substrate, and the surface of the cathode electrode is provided with the second photoconductive layer.

[0013] Further, the nano-cone structure comprises any one of a nano-wire structure, a nano-strip structure, a nano-tube structure, a nano-rod structure and a nano-needle structure.

[0014] Further, the first photoconductive layer comprises a P-type semiconductor nano-cone structure and an N-type photoconductor film arranged on the surface of the P-type semiconductor, or an N-type semiconductor nano-cone structure and a P-type photoconductor film arranged on the surface of the N-type semiconductor.

[0015] Further, the second photoconductive layer comprises an N-type semiconductor nano-cone structure and a P-type photoconductor film arranged on the surface of the N-type semiconductor, or a P-type semiconductor nano-cone structure and an N-type photoconductor film arranged on the surface of the P-type semiconductor.

[0016] A photomultiplier detector preparation method applied to the photomultiplier detector, comprising the following steps:

[0017] S1: preparing an anode substrate and a cathode substrate;

[0018] S2: preparing a sharp cone-shaped photoconductive layer on the surface of the anode substrate and the cathode substrate through micro-processing technology;

[0019] S3: setting the anode substrate and the cathode substrate in parallel on opposite sides;

[0020] S4: fixing the anode substrate and the cathode substrate by the insulator, and setting the photoconductive layers in a vacuum state, to obtain the photomultiplier detector.

[0021] Further, in step S2, the micro-processing technology is used to prepare the photoconductive layer in the form of a sharp cone on the surface of the anode substrate and the cathode substrate, comprising:

[0022] The N-type ZnO nanowire is prepared on the surface of the anode substrate and the cathode substrate by a thermal oxidation method, as an anode nano-cone structure semiconductor, and a P-type ZnS thin film anode photoconductor thin film is plated on the surface of the ZnO nanowire by an electron beam evaporation method, to obtain the photoconductive layer in the form of a sharp cone.

[0023] Compared with the prior art, the beneficial effects of the technical scheme of the present application are:

[0024] The present application utilizes the non-scattering characteristics of electron transport in vacuum to realize the collision ionization and photoelectric multiplication effect of high-energy electrons and photoconductors, utilizes the nano-cone structure photoconductive layer to regulate the electric field distribution and specific surface area, improves the electron transport efficiency and charge collection efficiency, and thus realizes the photoelectric detector with large area, high sensitivity, low dark current, fast response and long service life. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 The figure is a structure schematic diagram of the photomultiplier detector according to the present application;

[0026] Figure 2 The figure is a structure schematic diagram of the photomultiplier detector according to the present embodiment;

[0027] Figure 3 The figure is a flow schematic diagram of the preparation method of the photomultiplier detector according to the present application;

[0028] Figure 4 The figure is a morphology diagram of the ZnO nanowire according to the present embodiment;

[0029] Figure 5 The figure is a morphology diagram of the ZnS photoconductor thin film prepared on the surface of the ZnO nanowire according to the present embodiment;

[0030] Figure 6 The figure is a structure schematic diagram of the photomultiplier detector based on different high-diameter ratio nano-cone structure semiconductors according to the present embodiment;

[0031] Figure 7 The figure is a structure schematic diagram of the photomultiplier detector based on the nano-cone structure photoconductor according to the present embodiment.

[0032] In the drawings, 1, anode substrate; 2, anode electrode; 3, spacer; 4, cathode electrode; 5, cathode substrate; 6, anode nano-taper structure semiconductor; 7, anode photoconductor thin film; 8, cathode photoconductor thin film; 9, cathode nano-taper structure semiconductor; 10, anode base plate; 11, cathode base plate. DETAILED DESCRIPTION

[0033] The drawings are only for illustrative purposes and should not be construed as limiting the patent;

[0034] In order to better illustrate the embodiments, some parts of the drawings may be omitted, enlarged or reduced, and do not represent the actual size of the product;

[0035] For those skilled in the art, it is understandable that some well-known structures in the drawings and their descriptions may be omitted.

[0036] The technical solutions of the present application will be further described below in conjunction with the drawings and embodiments.

[0037] Embodiment 1

[0038] A photomultiplier type detector, as shown in Figure 1 It includes an anode base plate 10, a cathode base plate 11 and a spacer 3, the anode base plate 10 and the cathode base plate 11 are arranged in parallel, the surfaces of the anode base plate 10 and the cathode base plate 11 are provided with photoconductive layers, the anode base plate 10 and the cathode base plate 11 are fixedly connected through the spacer 3, the photoconductive layers are in a vacuum state, and the photoconductive layers are all in a taper structure.

[0039] In the specific implementation process, the anode base plate 10 and the cathode base plate 11 are arranged in parallel, the surfaces of the anode base plate 10 and the cathode base plate 11 are provided with photoconductive layers, and the photoconductive layers are in a vacuum state, which means that the gas pressure is ≤10 -3 Pa, the electrons move in the vacuum without scattering effect, so that the photoconductive layers between the anode base plate and the cathode base plate can accelerate the electrons to become high-energy electrons, thereby bombarding the photoconductive layers to produce collision ionization effect and photoelectric multiplication effect. In addition, the vacuum state can reduce the dark current of the detector, reduce the high-voltage breakdown, and improve the stability and service life of the detector.

[0040] Embodiment 2

[0041] This embodiment is based on embodiment 1 and further discloses the following content:

[0042] The photoconductive layer includes a plurality of nano-taper structure semiconductors and a photoconductor thin film arranged on the semiconductor. The resistivity of the photoconductive layer is 10 6 ~ 10 15 Ω·cm.

[0043] As shown in Figure 2 The photoconductive layer includes a first photoconductive layer disposed on the anode substrate 10 and a second photoconductive layer disposed on the cathode substrate 11, the first photoconductive layer includes a plurality of nano-taper structures of a first semiconductor 6 and a first photoconductor film 7 disposed on the first semiconductor 6, and the second photoconductive layer includes a plurality of nano-taper structures of a second semiconductor 9 and a second photoconductor film 8 disposed on the second semiconductor 9.

[0044] In a specific implementation, the photoconductor film includes Ga2O3, ZnO, GaN, ZnS, CdS, CdTe, a-Se, and perovskite, etc.

[0045] The spacer between the anode substrate and the cathode substrate has a height ranging from 30 to 1000 μm.

[0046] The anode substrate 10 includes an anode substrate 1 and an anode electrode 2, the anode electrode 2 is disposed on the anode substrate 1, and the first photoconductive layer is disposed on the surface of the anode electrode 2.

[0047] The cathode substrate 11 includes a cathode substrate 5 and a cathode electrode 4, the cathode electrode 4 is disposed on the cathode substrate 5, and the second photoconductive layer is disposed on the surface of the cathode electrode 4.

[0048] The nano-taper structure includes any one of a nano-wire structure, a nano-strip structure, a nano-tube structure, a nano-rod structure, and a nano-needle structure.

[0049] Embodiment 3

[0050] This embodiment is based on embodiments 1 and 2, and continues to disclose the following content:

[0051] The first photoconductive layer includes a P-type semiconductor of a nano-taper structure and an N-type photoconductor film disposed on the surface of the P-type semiconductor, or an N-type semiconductor of a nano-taper structure and a P-type photoconductor film disposed on the surface of the N-type semiconductor.

[0052] In a specific implementation, the P-type semiconductor of a nano-taper structure and the N-type photoconductor film disposed on the surface of the P-type semiconductor, or the N-type semiconductor of a nano-taper structure and the P-type photoconductor film disposed on the surface of the N-type semiconductor form a PN junction structure, the PN junction structure generates a high reverse bias, so that the photo-generated carriers accelerate to become high-energy carriers, the high-energy carriers collide with the lattice to ionize, avalanche effect occurs, and the photocurrent and sensitivity are improved. In addition, the high reverse bias generated by the PN junction can improve the response speed of the photo-generated carriers and reduce the dark current of the detector.

[0053] The second photoconductive layer comprises: N-type semiconductor with nano-taper structure and P-type photoconductor thin film arranged on the surface of the N-type semiconductor, or P-type semiconductor with nano-taper structure and N-type photoconductor thin film arranged on the surface of the P-type semiconductor.

[0054] In the working process of the detector, the anode electrode is applied with a positive voltage, and the cathode electrode is grounded, and the voltage range of the anode positive voltage is 100-5000V.

[0055] Embodiment 4

[0056] Based on the embodiments 1, 2 and 3, the following contents are further disclosed in this embodiment:

[0057] A preparation method of a photomultiplier detector, as shown in Figure 3 , applied to the photomultiplier detector, comprising the following steps:

[0058] S1: preparing an anode substrate 10 and a cathode substrate 11;

[0059] S2: preparing a photoconductive layer with a taper shape on the surface of the anode substrate 10 and the cathode substrate 11 by micro-processing technology;

[0060] S3: arranging the anode substrate 10 and the cathode substrate 11 in parallel on opposite sides;

[0061] S4: fixing the anode substrate 10 and the cathode substrate 11 by the insulator 3 to be insulated from each other, and setting the photoconductive layers to be in a vacuum state, to obtain the photomultiplier detector.

[0062] In the specific implementation process, step one: preparing an anode substrate: preparing a glass with an area of 5*5 cm 2 and a thickness of 3mm as a cathode substrate, using a magnetron sputtering technology to plate ITO electrode on the surface of the anode substrate as an anode electrode, a plating rate of 15nm / min, and an ITO electrode thickness of 540nm. A hot oxidation method is used to prepare N-type ZnO nanowires on the surface of the anode electrode as an anode nano-taper structure semiconductor. An electron beam evaporation is used to plate Zn film on the anode electrode, a plating rate of 0.6nm / s, a Zn film thickness of 2μm, and a Zn film area of 2*2 cm 2 . Then the sample is heated in the atmosphere to grow ZnO nanowires, a temperature of 470℃, and a time of 3 hours. The growth density of the ZnO nanowires is about 2.4*10 8 cm -2 , the height is about 2-4μm, and the tip diameter is about 20nm. An electron beam evaporation is used to plate a layer of P-type ZnS thin film anode photoconductor thin film on the surface of the ZnO nanowires, a plating rate of 0.05nm / s, and a ZnS thickness of 50nm.

[0063] As Figure 4 shown, Figure 4 is a ZnO nanowire morphology diagram.

[0064] As Figure 5 shown, Figure 5 is a ZnS photoconductor thin film morphology diagram prepared on the surface of the ZnO nanowire.

[0065] Step two: preparation of the cathode substrate: the cathode substrate, cathode electrode, cathode nano-taper structure semiconductor, cathode photoconductor thin film of the cathode substrate and the anode substrate, anode electrode, anode nano-taper structure semiconductor and anode photoconductor thin film of the anode substrate in S1 are the same.

[0066] Step three: assembly of the photomultiplier detector: the anode substrate and the cathode substrate are fixed together by the insulator, the material of the insulator 8 is ceramic sheet, and the height is 125 μm. The photoconductive layer between the anode substrate and the cathode substrate is kept in a vacuum state, and the vacuum degree is 1 × 10 5 Pa.

[0067] In the specific implementation process, when the photomultiplier detector is working, the anode electrode applies a positive voltage, and the cathode electrode is grounded. The working voltage of the anode positive voltage is 1000V.

[0068] Example 5

[0069] This embodiment is based on examples 1, 2, 3 and 4, and the following contents are further disclosed:

[0070] Step S3, the micro-processing technology is used to prepare a taper-shaped photoconductive layer on the surface of the anode substrate 10 and the cathode substrate 11, which includes:

[0071] The N-type ZnO nanowire is prepared on the surface of the anode substrate 10 and the cathode substrate 11 by a thermal oxidation method as an anode nano-taper structure semiconductor, and a P-type ZnS thin film anode photoconductor thin film is plated on the surface of the ZnO nanowire by an electron beam evaporation method, so as to obtain a taper-shaped photoconductive layer.

[0072] In the specific implementation process, the vacuum plating photoconductor thin film method includes magnetron sputtering, electron beam evaporation, thermal evaporation, atomic layer deposition, the micro-processing technology includes thermal oxidation technology, photolithography technology, etching technology, deposition technology and water bath technology, etc. The nano-taper type photoconductor improves the electron emission effect and improves the charge collection efficiency.

[0073] Example 6

[0074] This embodiment is based on examples 1, 2, 3, 4 and 5, and the following contents are further disclosed:

[0075] As Figure 6 shown, Figure 6 is a schematic diagram of a photomultiplier type detector structure based on different high aspect ratio nano-taper structure semiconductors. The greater the high aspect ratio of the nano-taper structure semiconductor, the lower the working voltage of the detector, and the higher the sensitivity. It is illustrated that the nano-taper type photoconductor can improve the electron emission effect and improve the charge collection efficiency, thereby reducing the working voltage of the detector and improving the sensitivity of the detector.

[0076] As Figure 7 shown, Figure 7 is a schematic diagram of a photomultiplier type detector structure based on a nano-taper structure photoconductor. Compared with the photoconductive layer adopting a PN junction structure, when the photoconductive layer of the embodiment adopts a single nano-taper structure photoconductor, the dark current of the detector rises, the response speed is slow, and the sensitivity decreases. This phenomenon illustrates that when the detector disclosed in the present application adopts a photoconductive layer with a PN junction structure, low dark current, fast response, and high sensitivity photoelectric detection can be achieved.

[0077] The same or similar reference signs correspond to the same or similar components;

[0078] The terms describing the positional relationship in the drawings are only used for exemplary illustration, and cannot be understood as a limitation on the patent;

[0079] Obviously, the above embodiments of the present application are only examples for clearly illustrating the present application, and are not intended to limit the embodiments of the present application. For those skilled in the art, on the basis of the above description, other different forms of changes or variations can also be made. Here, it is not necessary and impossible to exhaust all the embodiments. Any modification, equivalent replacement and improvement made within the spirit and principle of the present application shall be included in the protection scope of the claims of the present application.

Claims

1. A photomultiplier type detector, characterized by The application relates to a photomultiplier, which comprises an anode substrate (10), a cathode substrate (11) and a separator (3), the anode substrate (10) and the cathode substrate (11) are arranged in parallel opposition, the surfaces of the anode substrate (10) and the cathode substrate (11) are provided with photoconductive layers, the anode substrate (10) and the cathode substrate (11) are fixedly connected through the separator (3), the photoconductive layers are in a vacuum state, and the photoconductive layers are all in a sharp cone structure; wherein the photoconductive layer comprises a plurality of semiconductor nano sharp cone structures and a photoconductor film arranged on the semiconductor, specifically, the photoconductive layer comprises a first photoconductive layer arranged on the anode substrate (10) and a second photoconductive layer arranged on the cathode substrate (11), the first photoconductive layer comprises a plurality of first semiconductor nano sharp cone structures (6) and a photoconductor film (7) arranged on the first semiconductor (6), and the second photoconductive layer comprises a plurality of second semiconductor nano sharp cone structures (9) and a second photoconductor film (8) arranged on the second semiconductor (9). The anode substrate (10) comprises an anode substrate (1) and an anode electrode (2), the anode electrode (2) is arranged on the anode substrate (1), and the surface of the anode electrode (2) is provided with the first photoconductive layer; wherein the first photoconductive layer comprises a P-type semiconductor nano sharp cone structure and an N-type photoconductor film arranged on the surface of the P-type semiconductor or an N-type semiconductor nano sharp cone structure and a P-type photoconductor film arranged on the surface of the N-type semiconductor. The cathode substrate (11) comprises a cathode substrate (5) and a cathode electrode (4), the cathode electrode (4) is arranged on the cathode substrate (5), and the surface of the cathode electrode (4) is provided with the second photoconductive layer; wherein the second photoconductive layer comprises an N-type semiconductor nano sharp cone structure and a P-type photoconductor film arranged on the surface of the N-type semiconductor or a P-type semiconductor nano sharp cone structure and an N-type photoconductor film arranged on the surface of the P-type semiconductor.

2. Photomultiplier type detector according to claim 1, characterized in that The photoconductive layer comprises any one of a nano wire structure, a nano belt structure, a nano tube structure, a nano rod structure and a nano needle structure.

3. A method for fabricating a photomultiplier detector, characterized in that, The application is applied to the photomultiplier in any one of claims 1 to 2 and comprises the following steps: S1: preparing an anode substrate (10) and a cathode substrate (11); S2: arranging the anode substrate (10) and the cathode substrate (11) in parallel opposition on opposite sides; S3: preparing a sharp cone-shaped photoconductive layer on the surfaces of the anode substrate (10) and the cathode substrate (11) through a microprocessing technology; S4: fixedly connecting the anode substrate (10) and the cathode substrate (11) through a separator (3) to obtain the photomultiplier.

4. The method for fabricating a photomultiplier detector according to claim 3, characterized in that, In step S3, the sharp cone-shaped photoconductive layer is prepared on the surfaces of the anode substrate (10) and the cathode substrate (11) through a microprocessing technology, which comprises: The N-type ZnO nanowire is prepared on the surface of the anode substrate (10) and the cathode substrate (11) by a thermal oxidation method as an anode nanotaper structure semiconductor, and a P-type ZnS thin film anode photoconductor film is plated on the surface of the ZnO nanowire by an electron beam evaporation method, so that the photoconductive layer in the shape of a sharp taper is obtained.

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