Photomultiplier detector and preparation method thereof

Abstract

The invention relates to the field of photoelectric detectors, in particular to a photomultiplier detector and a preparation method thereof.The photomultiplier detector comprises an anode substrate, a cathode substrate and an isolator, the anode substrate and the cathode substrate are oppositely arranged in parallel, photoconductive layers are arranged on the surface of the anode substrate and the surface of the cathode substrate respectively, and the isolator is arranged on the surface of the anode substrate and the surface of the cathode substrate respectively. According to the invention, collision ionization and photomultiplication effects of high-energy electrons and photoconductors are realized by utilizing the characteristic that the electrons are transported in vacuum without scattering, and on the other hand, the electric field distribution and the specific surface area are regulated and controlled by utilizing the photoconductive layers with the nano pointed cone structures, so that the photoelectric multiplication effect is improved. And the electron transport efficiency and the charge collection efficiency are improved, so that the photoelectric detector which is large in area, high in sensitivity, low in dark current, quick in response and long in service life is realized.

Description

Technical Field

[0001] The present invention relates to the field of photoelectric detectors, and more specifically, to a photomultiplier detector and a preparation method thereof. Background Art

[0002] As a high-performance photoelectric conversion device, photomultiplier detectors have shown wide application potential in many high-tech fields, especially in key areas such as night vision imaging, space detection, medical imaging, and high-energy physics experiments. These fields have extremely high requirements for key performance indicators such as detector sensitivity, dark current, response speed, and life span.

[0003] The avalanche effect has been shown to be a very effective way to improve the photocurrent and sensitivity of photodetectors. Avalanche photodiodes are a typical application of this principle. By applying a high electric field inside the device, the photogenerated carriers will undergo an avalanche multiplication effect under the action of the electric field, thereby greatly enhancing the photocurrent and achieving high-sensitivity photodetection. However, despite its excellent performance in terms of sensitivity, avalanche photodiodes also face some challenges. For example, avalanche photodiodes are sensitive to temperature and have high dark currents, especially under high voltage working conditions, and are prone to thermal runaway, which affects the long-term stability and reliability of the device.

[0004] In order to overcome the limitations of avalanche photodiodes, researchers are constantly exploring new materials and structures in order to achieve photodetection with lower dark current and higher sensitivity. Among them, a new type of photomultiplier detector based on the avalanche effect came into being. This detector successfully reduces the dark current while maintaining high sensitivity by optimizing the electric field distribution and material selection. However, despite these advances, current photomultiplier detectors are still very demanding in terms of material selection, and it is difficult to prepare large-area imaging devices, which limits the scope of application of photomultiplier detectors in certain fields. Summary of the invention

[0005] In order to overcome at least one of the defects of the prior art, the present invention provides a photomultiplier detector and a preparation method thereof.

[0006] The present invention aims to solve the above technical problems at least to a certain extent.

[0007] In order to solve the above technical problems, the technical solution of the present invention is as follows:

[0008] A photomultiplier detector comprises an anode substrate, a cathode substrate and an insulator, wherein the anode substrate and the cathode substrate are arranged parallel to each other, and the surfaces of the anode substrate and the cathode substrate are both provided with photoconductive layers, the anode substrate and the cathode substrate are fixedly connected through the insulator, there is a vacuum state between the photoconductive layers, and the photoconductive layers are all pointed cone structures.

[0009] Furthermore, the photoconductive layer includes a semiconductor with a plurality of nano-cone structures and a photoconductor film disposed on the semiconductor.

[0010] Furthermore, the photoconductive layer includes a first photoconductive layer arranged on an anode substrate and a second photoconductive layer arranged on a cathode substrate, wherein the first photoconductive layer includes a first semiconductor having a plurality of nano-cone structures and a first photoconductor film arranged on the first semiconductor, and the second photoconductive layer includes a second semiconductor having a plurality of nano-cone structures and a second photoconductor film arranged on the second semiconductor.

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

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

[0013] Furthermore, the nano-cone structure includes any one of a nanowire structure, a nanobelt structure, a nanotube structure, a nanorod structure and a nanoneedle structure.

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

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

[0016] A method for preparing a photomultiplier detector, applied to the photomultiplier detector, comprises the following steps:

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

[0018] S2: preparing a photoconductive layer in a cone shape on the surfaces of the anode substrate and the cathode substrate by micromachining technology;

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

[0020] S4: The anode substrate and the cathode substrate are fixed to each other in an insulated manner through an insulator, and a vacuum state is set between the photoconductive layers to obtain a photomultiplier detector.

[0021] Further, in step S2, the step of using micromachining technology to prepare a photoconductive layer in a pointed cone shape on the surfaces of the anode substrate and the cathode substrate comprises:

[0022] N-type ZnO nanowires are prepared on the surfaces of the anode substrate and the cathode substrate as anode nanocone structure semiconductors by a thermal oxidation method, and a layer of P-type ZnS thin film anode photoconductor film is plated on the surface of the ZnO nanowires by an electron beam evaporation method to obtain a cone-shaped photoconductive layer.

[0023] Compared with the prior art, the technical solution of the present invention has the following beneficial effects:

[0024] The present invention utilizes the scattering-free transport property of electrons in a vacuum to realize the collision ionization and photomultiplier effect of high-energy electrons and photoconductors, and utilizes the nano-cone structure photoconductive layer to regulate the electric field distribution and specific surface area, thereby improving the electron transport efficiency and charge collection efficiency, thereby realizing a large-area, high-sensitivity, low dark current, fast response and long-life photodetector. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a schematic diagram of the structure of the photomultiplier detector of the present invention;

[0026] Figure 2 Schematic diagram of the structure of the photomultiplier detector described in this embodiment;

[0027] Figure 3 It is a schematic diagram of the process of preparing the photomultiplier detector according to the present invention;

[0028] Figure 4 This is the morphology of the ZnO nanowires described in this embodiment;

[0029] Figure 5 This is a morphology image of a ZnS photoconductor film prepared on the surface of ZnO nanowires as described in this embodiment;

[0030] Figure 6 This is a schematic diagram of the structure of a photomultiplier detector based on semiconductors with nano-cone structures of different aspect ratios as described in this embodiment;

[0031] Figure 7 This is a schematic diagram of the structure of a photomultiplier detector based on a nano-cone structure photoconductor described in this embodiment.

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

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

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

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

[0036] The technical solution of the present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0037] Example 1

[0038] A photomultiplier detector, such as Figure 1 As shown, it includes an anode substrate 10, a cathode substrate 11 and an insulator 3, the anode substrate 10 and the cathode substrate 11 are arranged parallel to each other, the surfaces of the anode substrate 10 and the cathode substrate 11 are both provided with photoconductive layers, the anode substrate 10 and the cathode substrate 11 are fixedly connected by the insulator 3, the photoconductive layers are in a vacuum state, and the photoconductive layers are all pointed cone structures.

[0039] In the specific implementation process, the anode substrate 10 and the cathode substrate 11 are arranged parallel to each other, and the surfaces of the anode substrate 10 and the cathode substrate 11 are both provided with a photoconductive layer, and the space between the photoconductive layers is in a vacuum state, and the vacuum state refers to the air pressure ≤10 -3 Pa, electrons move in a vacuum without scattering effects, so the vacuum state between the photoconductive layers of the anode substrate and the cathode substrate can accelerate the electrons to become high-energy electrons, thereby bombarding the photoconductive layer, generating impact ionization effect and photomultiplier effect. In addition, the vacuum state can reduce the dark current of the detector, reduce high-voltage breakdown, and improve the stability and working life of the detector.

[0040] Example 2

[0041] This embodiment further discloses the following contents based on the embodiment 1:

[0042] The photoconductive layer includes a plurality of semiconductors with nano-cone structures and a photoconductor film disposed on the semiconductor. The resistivity of the photoconductive layer is 10 6 ~10 15 Ω·cm.

[0043] like Figure 2 As shown, the photoconductive layer includes a first photoconductive layer arranged on an anode substrate 10 and a second photoconductive layer arranged on a cathode substrate 11, the first photoconductive layer includes a first semiconductor 6 with a plurality of nano-cone structures and a first photoconductor film 7 arranged on the first semiconductor 6, and the second photoconductive layer includes a second semiconductor 9 with a plurality of nano-cone structures and a second photoconductor film 8 arranged on the second semiconductor 9.

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

[0045] The height of the separator between the anode substrate and the cathode substrate ranges from 30 to 1000 μm.

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

[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-cone structure includes any one of a nanowire structure, a nanobelt structure, a nanotube structure, a nanorod structure and a nanoneedle structure.

[0049] Example 3

[0050] This embodiment further discloses the following contents based on Embodiments 1 and 2:

[0051] The first photoconductive layer includes: a P-type semiconductor with a nano-cone structure and an N-type photoconductor film arranged on the surface of the P-type semiconductor or an N-type semiconductor with a nano-cone structure and a P-type photoconductor film arranged on the surface of the N-type semiconductor.

[0052] In the specific implementation process, the P-type semiconductor of the nano-cone structure and the N-type photoconductor film arranged on the surface of the P-type semiconductor or the N-type semiconductor of the nano-cone structure and the P-type photoconductor film arranged on the surface of the N-type semiconductor form a PN junction structure, and the PN junction structure generates a high reverse bias voltage, so that the photogenerated carriers are accelerated to move into high-energy carriers, and the high-energy carriers collide with the lattice to ionize, and an avalanche effect occurs, thereby increasing the photocurrent and sensitivity. In addition, the high reverse bias voltage generated by the PN junction can increase the response speed of the photogenerated carriers and reduce the dark current of the detector.

[0053] The second photoconductive layer includes: an N-type semiconductor with a nano-cone structure and a P-type photoconductor film arranged on the surface of the N-type semiconductor or a P-type semiconductor with a nano-cone structure and an N-type photoconductor film arranged on the surface of the P-type semiconductor.

[0054] When the detector is working, a positive voltage is applied to the anode electrode, and the cathode electrode is grounded. The voltage range of the anode positive voltage is 100 to 5000V.

[0055] Example 4

[0056] This embodiment further discloses the following contents based on Embodiments 1, 2 and 3:

[0057] A method for preparing a photomultiplier detector, such as Figure 3 As shown, the photomultiplier detector is applied to the above-mentioned method, including the following steps:

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

[0059] S2: preparing a conical photoconductive layer on the surface of the anode substrate 10 and the cathode substrate 11 by micromachining technology;

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

[0061] S4: The anode substrate 10 and the cathode substrate 11 are fixed to each other in an insulated manner through the separator 3, and the space between the photoconductive layers is set to a vacuum state to obtain a photomultiplier detector.

[0062] In the specific implementation process, step 1: prepare the anode substrate: prepare a 5×5 cm 2 , 3mm thick glass was used as the cathode substrate, and ITO electrode was plated on the surface of the anode substrate using magnetron sputtering technology as the anode electrode. The coating rate was 15nm / min, and the ITO electrode thickness was 540nm. N-type ZnO nanowires were prepared on the surface of the anode electrode by thermal oxidation as the anode nanocone structure semiconductor. Zn film was plated on the anode electrode by electron beam evaporation, the coating rate was 0.6nm / s, the Zn film thickness was 2μm, and the Zn film area was 2×2cm 2 The sample was then placed in the atmosphere and heated to grow ZnO nanowires at 470°C for 3 hours. The growth density of the ZnO nanowires was about 2.4×10 8 cm -2 , with a height of about 2 to 4 μm and a tip diameter of about 20 nm. Then, a layer of P-type ZnS thin film anode photoconductor film is plated on the surface of the ZnO nanowires using electron beam evaporation, with a coating rate of 0.05 nm / s and a ZnS thickness of 50 nm.

[0063] like Figure 4 As shown, Figure 4 This is the morphology of ZnO nanowires.

[0064] like Figure 5 As shown, Figure 5 This is a morphology image of the ZnS photoconductor film prepared on the surface of ZnO nanowires.

[0065] Step 2: Prepare cathode substrate: the cathode substrate, cathode electrode, cathode nano-cone structure semiconductor, cathode photoconductor film of the cathode substrate are the same as the anode substrate, anode electrode, anode nano-cone structure semiconductor and anode photoconductor film of the anode substrate in S1.

[0066] Step 3: Assemble the photomultiplier detector: The anode substrate and the cathode substrate are fixed together by an isolator to insulate each other. The isolator 8 is made of a ceramic sheet with a height of 125 μm. The photoconductive layer between the anode substrate and the cathode substrate is kept in a vacuum state with a vacuum degree of 1×10 5 Pa.

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

[0068] Example 5

[0069] This embodiment, based on Embodiments 1, 2, 3 and 4, continues to disclose the following contents:

[0070] Step S3, using micromachining technology to prepare a photoconductive layer in a pointed cone shape on the surface of the anode substrate 10 and the cathode substrate 11, comprises:

[0071] N-type ZnO nanowires are prepared on the surfaces of the anode substrate 10 and the cathode substrate 11 as anode nanocone structure semiconductors by a thermal oxidation method, and a layer of P-type ZnS thin film anode photoconductor film is plated on the surface of the ZnO nanowires by an electron beam evaporation method to obtain a cone-shaped photoconductive layer.

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

[0073] Example 6

[0074] This embodiment, based on Embodiments 1, 2, 3, 4 and 5, continues to disclose the following contents:

[0075] like Figure 6 As shown, Figure 6 This is a schematic diagram of the structure of a photomultiplier detector based on nanocone structure semiconductors with different aspect ratios. The larger the aspect ratio of the nanocone structure semiconductor, the lower the working voltage of the detector and the higher the sensitivity. This shows that the nanocone photoconductor can improve the electron emission effect and the charge collection efficiency, thereby reducing the working voltage of the detector and improving the sensitivity of the detector.

[0076] like Figure 7 As shown, Figure 7 This is a schematic diagram of the structure of a photomultiplier detector based on a nano-cone structure photoconductor. Compared with a photoconductive layer using a PN junction structure, when the photoconductive layer of this embodiment uses a single nano-cone structure photoconductor, the dark current of the detector increases, the response speed is slow, and the sensitivity decreases. This phenomenon shows that when the detector disclosed in the present invention uses a PN junction structure photoconductive layer, low dark current, fast response and high sensitivity photoelectric detection can be achieved.

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

[0078] The terms used in the drawings to describe positional relationships are only used for illustrative purposes and should not be construed as limiting this patent;

[0079] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the embodiments here. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A photomultiplier detector, characterized in that: The invention comprises an anode substrate (10), a cathode substrate (11) and an insulator (3), wherein the anode substrate (10) and the cathode substrate (11) are arranged parallel to each other, and the surfaces of the anode substrate (10) and the cathode substrate (11) are both provided with a photoconductive layer, and the anode substrate (10) and the cathode substrate (11) are fixedly connected via the insulator (3), and the photoconductive layers are in a vacuum state, and the photoconductive layers are all of a pointed cone structure.

2. The photomultiplier detector according to claim 1, characterized in that: The photoconductive layer comprises a semiconductor with a plurality of nano-cone structures and a photoconductor film arranged on the semiconductor.

3. The photomultiplier detector according to claim 2, characterized in that: The photoconductive layer comprises a first photoconductive layer arranged on an anode substrate (10) and a second photoconductive layer arranged on a cathode substrate (11), wherein the first photoconductive layer comprises a first semiconductor (6) having a plurality of nano-cone structures and a first photoconductive film (7) arranged on the first semiconductor (6), and the second photoconductive layer comprises a second semiconductor (9) having a plurality of nano-cone structures and a second photoconductive film (8) arranged on the second semiconductor (9).

4. The photomultiplier detector according to claim 3, characterized in that: The anode substrate (10) comprises an anode substrate (1) and an anode electrode (2); the anode substrate (1) is provided with the anode electrode (2); and the surface of the anode electrode (2) is provided with the first photoconductive layer.

5. The photomultiplier detector according to claim 3, characterized in that: 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 second photoconductive layer is arranged on the surface of the cathode electrode (4).

6. The photomultiplier detector according to claim 2, characterized in that: The nano-cone structure includes any one of a nanowire structure, a nanobelt structure, a nanotube structure, a nanorod structure and a nanoneedle structure.

7. The photomultiplier detector according to claim 4, characterized in that: The first photoconductive layer includes: a P-type semiconductor with a nano-cone structure and an N-type photoconductor film arranged on the surface of the P-type semiconductor or an N-type semiconductor with a nano-cone structure and a P-type photoconductor film arranged on the surface of the N-type semiconductor.

8. The photomultiplier detector according to claim 5, characterized in that: The second photoconductive layer includes: an N-type semiconductor with a nano-cone structure and a P-type photoconductor film arranged on the surface of the N-type semiconductor or a P-type semiconductor with a nano-cone structure and an N-type photoconductor film arranged on the surface of the P-type semiconductor.

9. A method for preparing a photomultiplier detector, characterized in that: The method is applied to a photomultiplier detector as claimed in any one of claims 1 to 8, comprising the following steps: S1: preparing an anode substrate (10) and a cathode substrate (11); S2: preparing a photoconductive layer in a pointed cone shape on the surface of the anode substrate (10) and the cathode substrate (11) by micromachining technology; S3: arranging the anode substrate (10) and the cathode substrate (11) in parallel on opposite sides; S4: The anode substrate (10) and the cathode substrate (11) are fixed to each other in an insulated manner via an insulator (3), and a vacuum state is set between the photoconductive layers to obtain a photomultiplier detector.

10. The method for preparing a photomultiplier detector according to claim 9, characterized in that: Step S3, using micromachining technology to prepare a photoconductive layer in a pointed cone shape on the surface of the anode substrate (10) and the cathode substrate (11), comprises: N-type ZnO nanowires are prepared as anode nanocone structure semiconductors on the surfaces of the anode substrate (10) and the cathode substrate (11) by a thermal oxidation method, and a layer of P-type ZnS photoconductor film is plated on the surface of the ZnO nanowires by an electron beam evaporation method to obtain a photoconductive layer in a cone shape.

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