Photodetectors and their fabrication methods, spectrometers

Abstract

This application provides a photodetector, its fabrication method, and a spectrometer. In the photodetector provided in this application, a superlens substrate is provided on the light-incident side of the sensing substrate. The superlens unit focuses the incident light onto the absorption layer of the corresponding sensing unit in the sensing substrate. The absorption layer converts the light into heat energy, and the thermoelectric conversion layer converts the heat energy into an electrical signal, thus completing the detection of the incident light. Therefore, the superlens unit can increase the intensity and energy of the light incident on the sensing unit, and the absorption layer captures or absorbs most of the energy originating from the light and converts the energy form, thereby improving the sensitivity of the photodetector in detecting incident light.

Description

Technical Field

[0001] This application relates to the field of optical detection technology, and more specifically, to a photodetector and its fabrication method, and a spectrometer. Background Technology

[0002] With the development of photoelectric detection technology, spectrometers, as important analytical tools, are being used in more and more scenarios. Currently, portable spectrometers are one of the key research directions.

[0003] However, the sensitivity of portable spectrometers currently on the market is relatively low. Summary of the Invention

[0004] This application addresses the shortcomings of existing methods by proposing a photodetector, its fabrication method, and a spectrometer to solve the technical problem of low sensitivity in portable spectrometers in the prior art.

[0005] In a first aspect, embodiments of this application provide a photodetector, including: a sensing substrate and a superlens substrate disposed on the light-incident side of the sensing substrate;

[0006] The sensing substrate includes at least two sensing units, and the sensing unit includes a stacked absorption layer and a thermoelectric conversion layer;

[0007] The superlens substrate includes at least two superlens units, which are configured to focus incident light onto the absorption layer of the corresponding sensing unit, such that the absorption layer converts the light into heat energy and conducts it to the thermoelectric conversion layer, which is configured to convert the heat energy into an electrical signal.

[0008] Secondly, embodiments of this application provide a spectrometer, including: a photodetector as provided in the first aspect above.

[0009] Thirdly, embodiments of this application provide a method for fabricating a photodetector, comprising:

[0010] Fabricating a sensing substrate including at least two sensing units includes: forming a thermoelectric conversion layer on one side of the substrate, forming a reflective electrode on one side of the thermoelectric conversion layer based on a patterning process, forming an elastic dielectric structure on one side of the reflective electrode, forming a light-transmitting electrode on one side of the elastic dielectric structure based on a patterning process, and forming a nanoparticle layer including at least two metal nanoparticles on one side of the light-transmitting electrode.

[0011] The superlens substrate is attached to the light-incident side of the sensing substrate, so that the light incident on the superlens unit in the superlens substrate is focused onto the absorption layer of the sensing unit, so that the absorption layer converts the light into heat energy and conducts it to the thermoelectric conversion layer. The thermoelectric conversion layer is configured to convert heat energy into electrical signals.

[0012] The beneficial technical effects of the technical solutions provided in this application include:

[0013] In the photodetector provided in this application embodiment, by providing a superlens substrate on the light-incident side of the sensing substrate, the superlens unit focuses the incident light onto the absorption layer of the corresponding sensing unit in the sensing substrate. The absorption layer converts the light into heat energy, and the thermoelectric conversion layer converts the heat energy into an electrical signal, thus completing the detection of the incident light. In this way, the intensity and energy of the light incident on the sensing unit can be increased by the superlens unit, and most of the energy from the light energy can be captured or absorbed by the absorption layer and converted into energy form, thereby improving the sensitivity of the photodetector in detecting incident light.

[0014] Additional aspects and advantages of this application will be set forth in part in the description which follows, and will become apparent from the description or may be learned by practice of this application. Attached Figure Description

[0015] The above and / or additional aspects and advantages of this application will become apparent and readily understood from the following description of the embodiments taken in conjunction with the accompanying drawings, wherein:

[0016] Figure 1 A top view schematic diagram of the structure of a photodetector provided in an embodiment of this application;

[0017] Figure 2 Provided for the embodiments of this application Figure 1 A schematic diagram of the AA-axis cross-sectional structure of the photodetector shown.

[0018] Figure 3 Provided for the embodiments of this application Figure 2 A schematic diagram of the sensing substrate in the photodetector shown;

[0019] Figure 4 Provided for the embodiments of this application Figure 3 The light energy absorption distribution diagram of the sensing substrate is shown.

[0020] Figure 5 Provided for the embodiments of this application Figure 3 The diagram shows the relationship between the light absorption intensity in the sensing substrate and the thickness of the elastic medium structure and the wavelength of the incident light.

[0021] Figure 6 Provided for the embodiments of this application Figure 3 A schematic diagram showing the relationship between the light energy absorption intensity in the sensing substrate and the wavelength and angle of incidence of the incident light.

[0022] Figure 7 Provided for the embodiments of this application Figure 3The diagram shows the relationship between the light absorption intensity and the wavelength of the incident light in the sensing substrate with a fixed thickness of the elastic medium structure.

[0023] Figure 8 Provided for the embodiments of this application Figure 2 A schematic diagram of the superlens substrate in the photodetector shown.

[0024] Figure 9 A bottom view of the superlens substrate in another photodetector provided in an embodiment of this application;

[0025] Figure 10 Provided for the embodiments of this application Figure 9 A schematic diagram of the phase change of the superlens substrate shown;

[0026] Figure 11 Provided for the embodiments of this application Figure 9 A schematic diagram of the energy distribution of focused light rays in the superlens substrate shown.

[0027] Figure 12a A schematic diagram of the structure after the thermoelectric conversion layer is fabricated in the method for fabricating the photodetector provided in the embodiments of this application;

[0028] Figure 12b A schematic diagram of the structure after the reflective electrode is fabricated in the method for fabricating the photodetector provided in the embodiments of this application;

[0029] Figure 12c A schematic diagram of the structure after the elastic dielectric structure is fabricated in the method for fabricating the photodetector provided in the embodiments of this application;

[0030] Figure 12d A schematic diagram of the structure of metal nanoparticles after they have been fabricated in the method for fabricating a photodetector provided in this application embodiment;

[0031] Figure 13a A schematic diagram of the structure after the initial layer is obtained in the method for fabricating the photodetector provided in the embodiments of this application;

[0032] Figure 13b A schematic diagram of the structure after the photoresist layer is fabricated in the method for fabricating the photodetector provided in the embodiments of this application;

[0033] Figure 13c This is a schematic diagram of the structure after the columnar structure is fabricated in the method for fabricating the photodetector provided in the embodiments of this application.

[0034] Explanation of reference numerals in the attached figures:

[0035] 11-Sensing unit; 111-Absorption layer; 1111-Reflective electrode; 1112-Elastic dielectric structure; 1113-Transparent electrode; 1114-Metal nanoparticles; 112-Thermoelectric conversion layer; 113-Substrate;

[0036] 20-Superlens substrate;

[0037] 21-Superlens unit; 211-Transparent substrate; 212-Columnar structure;

[0038] 201 - Initial layer; 202 - Photoresist layer;

[0039] 30 - Connection layer. Detailed Implementation

[0040] The embodiments of this application are described below with reference to the accompanying drawings. It should be understood that the embodiments described below with reference to the accompanying drawings are exemplary descriptions for explaining the technical solutions of the embodiments of this application, and do not constitute a limitation on the technical solutions of the embodiments of this application.

[0041] Those skilled in the art will understand that, unless specifically stated otherwise, the singular forms “a,” “an,” “the,” and “the” used herein may also include the plural forms. It should be further understood that the word “comprising” as used in this application's specification means the presence of the stated features, integers, steps, and / or operations, but does not exclude implementation as supported by this art, other features, information, data, steps, operations, and / or combinations thereof. The term “and / or” as used herein refers to at least one of the items defined by the term; for example, “A and / or B” can be implemented as “A,” or as “B,” or as “A and B.”

[0042] To make the objectives, technical solutions, and advantages of this application clearer, the embodiments of this application will be described in further detail below with reference to the accompanying drawings.

[0043] First, the relevant technologies involved in this application will be explained:

[0044] Photodetectors are crucial components of spectrometers. Their primary working principle is to convert incident light into electrical signals. Currently, photodetectors mainly fall into two categories: those utilizing the light effect and those utilizing the photothermal effect. The relatively low sensitivity of portable spectrometers is primarily due to the photodetector's inability to effectively detect incident light, resulting in low sensitivity.

[0045] The photodetector, its fabrication method, and spectrometer provided in this application are intended to address the aforementioned technical problems of the prior art.

[0046] The technical solution of this application and how it solves the above-mentioned technical problems are described in detail below with specific embodiments. It should be noted that the following embodiments can be referenced, borrowed, or combined with each other, and the same terms, similar features, and similar implementation steps in different embodiments will not be described again.

[0047] This application provides a photodetector, the structural schematic of which is shown below. Figure 1 As shown, Figure 1 A schematic diagram of the AA-direction cross-sectional structure of the photodetector shown is as follows: Figure 2 As shown. The photodetector includes: a sensing substrate and a superlens substrate 20 disposed on the light-incident side of the sensing substrate.

[0048] The sensing substrate includes at least two sensing units 11, each sensing unit 11 including a stacked absorption layer 111 and a thermoelectric conversion layer 112; the superlens substrate 20 includes at least two superlens units 21, each superlens unit 21 being configured to focus incident light onto the absorption layer 111 of the corresponding sensing unit 11, such that the absorption layer 111 converts the light into heat energy and conducts it to the thermoelectric conversion layer 112, which is configured to convert the heat energy into an electrical signal.

[0049] In the photodetector provided in this application embodiment, by providing a superlens substrate 20 on the light-incident side of the sensing substrate, the superlens unit 21 focuses the incident light onto the absorption layer 111 of the sensing unit 11 in the sensing substrate. The absorption layer 111 converts the light into heat energy, and the thermoelectric conversion layer 112 converts the heat energy into an electrical signal, thus completing the detection of the incident light. In this way, the intensity and energy of the light incident on the sensing unit 11 can be increased by the superlens unit, and most of the energy from the light energy can be captured or absorbed by the absorption layer 111 and converted into energy form, thereby improving the sensitivity of the photodetector in detecting the incident light.

[0050] In this embodiment, the sensing substrate includes at least two sensing units 11, optionally, such as Figure 1 As shown, the sensing substrate array has multiple sensing units 11 arranged thereon. Optionally, the photoelectric sensor provided in this embodiment is a photothermal effect detector, such as... Figure 2 As shown, the sensing unit 11 includes a stacked absorption layer 111 and a thermoelectric conversion layer 112. The absorption layer 111 is used to convert absorbed light energy into heat energy, and the thermoelectric conversion layer 112 is used to convert heat energy into electrical signals.

[0051] In the embodiments of this application, such as Figure 1 As shown, the superlens substrate 20 is disposed on the light-transmitting side of the sensing substrate. Due to the blocking effect of the superlens substrate 20, Figure 1 The reference numerals for the sensing substrate are not shown in the attached diagram.

[0052] Optionally, such as Figure 1 As shown, the superlens substrate 20 includes an array of superlens units 21, with each sensing unit 11 corresponding to one superlens unit 21, such as... Figure 1 As shown, the orthographic projection of the sensing unit 11 onto the sensing substrate is located within the orthographic projection of the sensing unit 11 onto the sensing substrate. Optionally, the superlens unit 21 is circular.

[0053] In the embodiments of this application, such as Figure 2 As shown, each superlens unit 21 is configured to focus incident light onto the absorption layer 111 of the corresponding sensing unit 11. That is, the superlens unit 21 is used to focus incident light onto the absorption layer 111 of the sensing unit 11 located directly below it, thereby increasing the intensity of the light incident on the sensing unit 11. This allows the absorption layer 111 to convert the light into heat, and then the thermoelectric conversion layer 112 converts the heat energy into an electrical signal, thus completing the detection of the incident light. This allows a small amount of light to be focused by the superlens unit 21 to excite the sensing unit 11 to generate an electrical signal, thereby improving the sensitivity of the photodetector in detecting incident light and improving the sensitivity and detection accuracy of the spectrometer using the photodetector.

[0054] Meanwhile, in this embodiment, the photoelectric sensor uses a superlens substrate 20. Since the superlens unit 21 has the characteristics of small size and high planarity compared with the geometric optical lens, the size of the photoelectric sensor can be reduced, which is beneficial to the thinning of the spectrometer.

[0055] Optionally, the thermoelectric conversion layer 112 is made of aluminum nitride, which has good thermoelectric properties, thus enabling the absorption of heat to be converted into electrical signals.

[0056] It should be noted that there is a corresponding functional relationship between the frequency of the incident light and the heat energy converted by the absorption layer 111 and the electrical signal converted by the thermoelectric conversion layer 112. Specifically, this can be determined by equations (1) and (2).

[0057]

[0058] In relation (1), The temperature rise caused by incident radiation is represented by η, the absorption and excitation rates are represented by Φ0, and the radiant power is represented by R. th This represents thermal resistance, τ. th This represents the response time, and ω represents the frequency of the incident radiation.

[0059]

[0060] In relation (2), i pThis represents the detection current output by the thermoelectric conversion layer 112, where A represents the area of ​​the sensing unit 11, and p... tot This represents the total response rate of the thermoelectric material, where T represents temperature and t represents time.

[0061] The inventor tested the embodiments provided in this application. Figure 3 The sensing substrate shown is used as an example. After processing the data, the following results are obtained: Figures 4-7 The results are shown below. Specific examples will be used to illustrate this further. Figures 4-7 The results shown will be explained in detail.

[0062] In one embodiment of this application, the absorption layer 111 includes: a reflective electrode 1111, an elastic dielectric structure 1112, a light-transmitting electrode 1113, and a nanoparticle layer, which are sequentially stacked on one side of the thermoelectric conversion layer 112. The nanoparticle layer includes at least two metal nanoparticles 1114. The elastic dielectric structure 1112 varies along its dimension perpendicular to the thermoelectric conversion layer 112 with the change of the electric field applied to the reflective electrode 1111 and the light-transmitting electrode 1113.

[0063] In the embodiments of this application, such as Figure 2 and Figure 3 As shown, the absorption layer 111 is disposed on the side of the thermoelectric conversion layer 112 away from the substrate 113, thereby enabling the light focused onto the absorption layer 111 to be converted into heat.

[0064] Specifically, such as Figure 2 and Figure 3 As shown, the absorption layer 111 includes a reflective electrode 1111 disposed on the side of the thermoelectric conversion layer 112 away from the substrate 113, and the reflective electrode 1111 is made of an opaque material. An elastic dielectric structure 1112 is disposed on the side of the reflective electrode 1111 away from the substrate 113, for converting light into heat, and the thickness of the elastic dielectric structure 1112 changes under excitation conditions (e.g., an electric field). A light-transmitting electrode 1113 is disposed on the side of the elastic dielectric structure 1112 away from the substrate 113, and the light-transmitting electrode 1113 has high light transmittance to ensure the amount of light incident on the elastic dielectric structure 1112. A nanoparticle layer is disposed on the side of the light-transmitting electrode 1113 away from the substrate 113, and the nanoparticle layer includes multiple metal nanoparticles 1114.

[0065] In this embodiment, the metal nanoparticles 1114, the elastic dielectric structure 1112, and the reflective electrode 1111 constitute an electrical conductor and a magnetic conductor, so that both the electric field component and the magnetic field component of the light incident into the absorption layer 111 are absorbed, thereby preventing the incident light from escaping from the absorption layer 111, further improving the absorption rate and utilization rate of the incident light, and thus improving the sensitivity of the photodetector in detecting the incident light.

[0066] Optionally, the elastic dielectric structure 1112, along its dimension perpendicular to the thermoelectric conversion layer 112, is negatively correlated with the magnitude of the electric field applied to the reflective electrode 1111 and the light-transmitting electrode 1113.

[0067] After testing the photodetector provided in the embodiments of this application using simulation software, the inventors of this application discovered that the energy of the incident light is localized within the absorption layer 111.

[0068] Optionally, in this embodiment, the focal length of the superlens unit 21 falls exactly on the metal nanoparticles 1114.

[0069] In the embodiments of this application, such as Figure 4 As shown, Figure 3 The diagram shows the light absorption energy distribution of the sensing substrate. Specifically, Figure 4 for Figure 3 The diagram shows the light energy distribution of the cross-sectional structure of the sensing substrate along the XY direction. Figure 4 In the diagram, the horizontal axis represents the horizontal direction X, and the vertical axis represents the vertical direction Y. Figure 4 The brighter the color, the more light energy it absorbs. Figure 4 As can be seen, the light is mainly localized near the metal nanoparticles 1114 in the absorption layer 111, which allows the light to be incident on the elastic medium structure 1112 and absorbed.

[0070] In one embodiment of this application, the elastic medium structure 1112 has a dimension of not less than 4 nanometers and not more than 20 nanometers along a dimension perpendicular to the thermoelectric conversion layer 112.

[0071] In this embodiment, the elastic dielectric structure 1112 varies in thickness from 4 nm to 20 nm along a dimension perpendicular to the thermoelectric conversion layer 112. By limiting the thickness variation range of the elastic dielectric structure 1112, the distance between the metal nanoparticles 1114 and the reflective electrode 1111 varies between 4 nm and 20 nm. This ensures that the metal nanoparticles 1114, the elastic dielectric structure 1112, and the reflective electrode 1111 constitute an electrical conductor and a magnetic conductor, respectively, so that both the electric and magnetic field components of the light incident on the absorption layer 111 are absorbed.

[0072] Optionally, the elastic medium structure 1112 may include materials such as polyacrylate and silicone rubber.

[0073] In one embodiment of this application, as the elastic medium structure 1112 changes along the dimension perpendicular to the thermoelectric conversion layer 112, the absorption spectrum of the sensing unit 11 is not less than 400 nm and not greater than 750 nm.

[0074] It should be noted that the absorbed laser light of the sensing unit 11 refers to the wavelength range of light that the absorption layer 111 of the sensing unit 11 can completely absorb. The absorption spectrum range of the sensing unit 11 is related to the distance between the metal nanoparticles 1114 and the reflective electrode 1111, as well as the thickness and width of the metal nanoparticles 1114.

[0075] In this embodiment, with the thickness and width of the metal nanoparticles 1114 determined, the size change of the elastic medium structure 1112 is controlled by light to control the change in distance between the metal nanoparticles 1114 and the reflective electrode 1111. This allows the absorption layer 111 in the sensing unit 11 to absorb light of different wavelengths, so that the absorption spectrum of the sensing unit 11 covers the wavelength range of visible light.

[0076] In the embodiments of this application, such as Figure 5 As shown, Figure 3 The diagram shows the relationship between the light absorption intensity in the sensing substrate and the thickness of the elastic medium structure and the wavelength of the incident light. Figure 5 In the diagram, the horizontal axis represents the thickness of the elastic medium structure 1112, and the vertical axis represents the wavelength of the incident light. Figure 5 The brighter the color, the more light energy it absorbs. Figure 5 It can be seen that the absorption intensity of the absorption layer 111 for different wavelengths is related to the thickness of the elastic medium structure 1112. Specifically, as the thickness of the elastic medium structure 1112 increases, the absorption intensity of the absorption layer 111 for shorter wavelengths becomes stronger, while the absorption intensity for longer wavelengths becomes weaker.

[0077] Optionally, by increasing the applied electric field of the reflective electrode 1111 and the light-transmitting electrode 1113, the elastic medium structure 1112 can be compressed, thus reducing the thickness of the elastic medium structure 1112. By decreasing the applied electric field, the elastic medium structure 1112 can gradually rebound. After the applied electric field is removed, the elastic medium structure 1112 rebounds to its initial thickness. Thus, by controlling the magnitude of the applied electric field, the absorption spectrum of the sensing unit 11 can be dynamically adjusted, thereby improving the flexibility of the photodetector.

[0078] In this embodiment, all metal nanoparticles 1114 in each sensing unit 11 have the same size, that is, all metal nanoparticles 1114 have the same thickness and the same width, which enables different regions of the photodetector to have different absorption spectra, thereby improving the flexibility of the photodetector and expanding the application scenarios of the photodetector.

[0079] Optionally, the metal nanoparticles 1114 of all sensing units 11 in the sensing substrate are of the same size.

[0080] Those skilled in the art, after measuring the photodetector provided in this application, understand that as the thickness of the elastic medium structure 1112 increases, the wavelength of the light with the greatest absorption intensity in the absorption layer 111 of the sensing unit 11 gradually decreases; for incident light of the same wavelength, as the incident angle changes from perpendicular to the absorption layer 111 to a range of approximately 60° with respect to the absorption layer 111, the absorption intensity of the absorption layer 111 remains constant, that is, the absorption layer 111 can absorb light incident at large angles, thereby further improving the utilization rate of the incident light.

[0081] In the embodiments of this application, such as Figure 6 As shown, Figure 3 The diagram shows the relationship between the light absorption intensity in the sensing substrate and the wavelength and angle of the incident light. Figure 6 In the diagram, the horizontal axis represents the angle of incidence of the incident light ray, and the vertical axis represents the wavelength of the incident light ray. Figure 6 The brighter the color, the more light energy it absorbs. Figure 6 It can be seen that as the incident angle changes from 0 (i.e. the incident light is perpendicular to the sensing substrate) to 60°, the absorption rate of the absorption layer 111 for incident light with a wavelength of 600-650nm remains unchanged.

[0082] In the embodiments of this application, such as Figure 7 As shown, Figure 3 The diagram shows the relationship between light absorption intensity and incident light wavelength in a sensing substrate with a fixed thickness of the elastic medium structure. Figure 7 In the graph, the horizontal axis represents the wavelength of the incident light, and the vertical axis represents the reflectivity. From... Figure 7 It can be seen that when the elastic medium structure is at this thickness, the reflectivity of the incident light wavelength corresponding to the lowest point of the curve is the lowest, that is, the absorption intensity of the absorption layer 111 for the incident light wavelength is greater.

[0083] In one embodiment of this application, the diameter of the metal nanoparticles 1114 is not less than 45 nanometers and not greater than 65 nanometers.

[0084] In this embodiment, the metal nanoparticles 1114 are parallel to the thermoelectric conversion layer 112, that is, the diameter of the metal nanoparticles 1114 is in the range of 45nm-65nm. By controlling the diameter of the metal nanoparticles 1114, the absorption spectrum range of the sensing unit 11 can be controlled.

[0085] In one embodiment of this application, the metal nanoparticles 1114 have a size of not less than 50 nanometers and not more than 80 nanometers along the axis perpendicular to the thermoelectric conversion layer 112.

[0086] In this embodiment, the metal nanoparticles 1114 are 50nm-80nm thick along the dimension perpendicular to the thermoelectric conversion layer 112. By controlling the width of the metal nanoparticles 1114, the absorption spectrum range of the sensing unit 11 can be controlled.

[0087] Those skilled in the art can determine the width and thickness of the metal nanoparticles 1114 in the photodetector according to the specific application scenario of the photodetector, so that the absorption spectrum of the photodetector can meet the requirements. After the width and thickness of the metal nanoparticles 1114 are determined, the absorption spectrum of the sensing unit 11 can be dynamically adjusted by controlling the increase of the applied electric field of the reflective electrode 1111 and the transparent electrode 1113.

[0088] In this embodiment, the shape of the metal nanoparticles 1114 can be a symmetrical three-dimensional shape such as a cube, cuboid, sphere, or ellipsoid. Those skilled in the art can select and manufacture metal nanoparticles 1114 of a suitable shape according to the actual production process.

[0089] In one embodiment of this application, the material of the reflective electrode 1111 includes any one of gold, silver and aluminum.

[0090] In this embodiment, since the reflective electrode 1111 needs to have good reflectivity, the material of the reflective electrode 1111 includes metal materials with high reflectivity and high conductivity such as gold, silver and aluminum, so as to ensure that the light incident on the absorption layer 111 can be absorbed by the elastic medium structure 1112 and will not be transmitted through the reflective electrode 1111.

[0091] Optionally, the photodetector provided in this application embodiment can be integrated into portable display devices such as mobile phones and tablets, for example, integrated into a display panel. The display panel includes a sensing substrate. In order to facilitate manufacturing, and because the light-transmitting electrode 1113 and the elastic dielectric structure 1112 have good light transmittance, the light-transmitting electrode 1113 and the elastic dielectric structure 1112 can be set as a whole layer. The reflective electrode 1111 is obtained by patterning a reflective conductive layer to ensure the light transmittance of the display panel.

[0092] In one embodiment of this application, the superlens unit 21 includes a light-transmitting substrate 211 and at least two columnar structures 212 of different diameters disposed on one side of the light-transmitting substrate 211; the diameter of each columnar structure 212 gradually decreases along the direction from the center of the light-transmitting substrate 211 to the edge.

[0093] In the embodiments of this application, such as Figure 2 and Figure 8 As shown, the superlens unit 21 includes a light-transmitting substrate 211 and at least two columnar structures 212 with different diameters. Optionally, the light-transmitting substrate 211 is a glass substrate.

[0094] like Figure 2 and Figure 8 As shown, along the direction from the center of the light-transmitting substrate 211 to the edge, the diameter of each columnar structure 212 gradually decreases, that is, the diameter of the columnar structure 212 located at the center of the light-transmitting substrate 211 is larger than the diameter of other columnar structures 212, thereby enabling the superlens unit 21 to focus the incident light.

[0095] Optionally, such as Figure 8 As shown, the superlens unit 21 includes five columnar structures 212 with different diameters. The columnar structure 212a located at the center of the light-transmitting substrate 211 has the largest diameter, followed by the columnar structures 212b closest to both sides of 212a, then 212c, and finally 212d. The outermost columnar structure 212e has the smallest diameter. Optionally, as... Figure 8 As shown, along the direction from the center of the light-transmitting substrate 211 to the edge, the diameters of the columnar structures 212a, 212b, 212c, 212d, and 212e gradually decrease.

[0096] Those skilled in the art, after measuring the photodetector provided in this application, understand that each superlens unit 21 transmits light at different phases not less than 0° and not greater than 360°. Due to the focusing effect of the superlens unit 21, the incident light is almost uniformly focused to the focal point.

[0097] In one embodiment of this application, a plurality of columnar structures 212 form at least two concentrically arranged columnar structure ring groups. In the same columnar structure ring group, the diameters of the columnar structures 212 are all equal. In any two adjacent columnar structure ring groups, the diameter of the columnar structure 212 in the outer columnar structure ring group is smaller than the diameter of the columnar structure 212 in the inner columnar structure ring group.

[0098] In the embodiments of this application, such as Figure 9 As shown, the light-transmitting substrate 211 of the superlens unit 21 is circular in shape, and the superlens unit 21 includes three columnar structures 212 with different diameters.

[0099] Specifically, the columnar structure 212a located at the center of the light-transmitting substrate 211 has the largest diameter. Two columnar structure ring groups are arranged around the columnar structure 212a and are concentric with the center of the light-transmitting substrate 211. The outer columnar structure ring group includes twelve columnar structures 212c with the same diameter, and the inner columnar structure ring group includes eight columnar structures 212b with the same diameter. The diameter of columnar structure 212c is smaller than the diameter of columnar structure 212b and the diameter of columnar structure 212a, and the diameter of columnar structure 212b is smaller than the diameter of columnar structure 212a.

[0100] It should be noted that, Figure 9 The image merely illustrates two concentrically arranged columnar ring structures. Those skilled in the art can set different numbers of columnar ring structures according to actual needs, and each columnar ring structure may include different numbers of columnar structures 212.

[0101] The inventor tested the embodiments provided in this application. Figure 9 The superlens unit 21 shown is used, and after organizing the data, the following is obtained: Figures 10-11 The results are shown.

[0102] In the embodiments of this application, such as Figure 10 As shown, Figure 9 The diagram shows the phase change of the superlens substrate. Specifically, Figure 10 for Figure 9 A schematic diagram of the phase change of the superlens substrate shown from a top-view perspective. Figure 10 As shown, using Figure 9 The arrangement of the columnar structure 212 shown enables each superlens unit 21 to transmit light at different phases from 0° to 360°.

[0103] Figure 11 for Figure 9 A schematic diagram of the energy distribution of the focused light rays on the superlens substrate is shown. Figure 11 middle, Figure 11 The brighter the color, the more light energy it absorbs.

[0104] Figure 11 In the diagram, (a) and (b) represent the energy distribution of the focused Blue light rays in the cross-sections of the superlens unit 21 in different directions, and (c) represents the energy distribution at the focal point. The positions with the strongest energy in (a) and (b) are the focal points of the superlens unit 21, where the superlens unit 21 has the strongest focusing ability for Blue light.

[0105] Figure 11In the diagram, (d) and (e) represent the energy distribution of the Green light focused rays in the cross-section of the superlens unit 21 in different directions, and (f) represents the energy distribution at the focal point. The positions with the strongest energy in (d) and (e) are the focal points of the superlens unit 21, where the superlens unit 21 has the strongest focusing ability for green light.

[0106] Figure 11 In the diagram, (g) and (h) represent the energy distribution diagram of the focused Red light rays in the cross-section of the superlens unit 21 in different directions, and (i) represents the energy distribution diagram at the focal point. The positions with the strongest energy in (g) and (h) are the positions where the superlens unit 21 is located, and the superlens unit 21 has the strongest focusing ability for red light at this focal point.

[0107] In summary regarding Figure 11 As can be seen from the description, the superlens unit 21 has good focusing ability for blue light, green light and red light.

[0108] In one embodiment of this application, in the same superlens unit 21, all columnar structures 212 have the same size along the direction perpendicular to the light-transmitting substrate 211.

[0109] In this embodiment of the application, for the same superlens unit 21, all columnar structures 212 have the same size along the direction perpendicular to the light-transmitting substrate 211, that is, all columnar structures 212 have the same thickness.

[0110] Optionally, in the superlens substrate 20, all columnar structures 212 have the same thickness, thereby making all superlens units 21 have the same focal length. This facilitates the reduction of the photoelectric sensor volume, which is beneficial for the thinning of the spectrometer.

[0111] In one embodiment of this application, the columnar structure 212 has a dimension of not less than 400 nanometers and not more than 1 micrometer along the direction perpendicular to the light-transmitting substrate 211;

[0112] In this embodiment, the dimension of the columnar structure 212 along the direction perpendicular to the light-transmitting substrate 211, i.e., the thickness of the columnar structure 212, ranges from 1 μm (micrometer) to 400 nm. Those skilled in the art can select a suitable thickness for the columnar structure 212 according to actual needs. By adjusting the thickness, number, and arrangement of the columnar structures 212, superlens units 21 with different focal lengths can be obtained. Optionally, in this embodiment, the thickness of the columnar structure 212 is 600 nm.

[0113] In one embodiment of this application, the diameter of the columnar structure 212 is not less than 40 nanometers and not more than 200 nanometers.

[0114] In this embodiment of the application, the diameter range of all columnar structures 212 in the superlens substrate 20 is 40nm-200nm.

[0115] In this embodiment, the columnar structure 211 is made of light-transmitting materials such as titanium dioxide, gallium nitride, and silicon nitride. By refraction through the columnar structure 211, the light path of the incident light is changed, thereby achieving the effect of focusing the incident light.

[0116] In this embodiment, the superlens unit 21 may further include a liquid crystal layer and a driving electrode, which are disposed on one side of the lens substrate 211. By applying an electric field through the driving electrode, the transmittance of the liquid crystal layer is changed, thereby adjusting the movement of the focal point of the superlens unit 21. This enables dynamic adjustment of the focal point of the superlens unit 21 and further improves the utilization rate of light.

[0117] In one embodiment of this application, the photodetector further includes a connection layer 30 disposed between the sensing substrate and the superlens substrate 20; the thickness of the connection layer 20 is less than the focal length of the superlens unit 11.

[0118] In this embodiment of the application, combined with Figure 1 and Figure 2 It can be seen that a connection layer 30 is provided between the sensing substrate and the superlens substrate 20, and the connection layer 30 is used to achieve a fixed connection between the sensing substrate and the superlens substrate 20.

[0119] Optionally, the material of the connecting layer 30 includes PMMA (Poly-Methyl Meth-Acrylate), which has high light transmittance, thereby avoiding the loss of light emitted from the superlens unit 21 and ensuring the utilization rate of light.

[0120] Based on the same inventive concept, this application provides a spectrometer, including: any of the photodetectors provided in the above embodiments.

[0121] In this embodiment, since the spectrometer uses any of the photodetectors provided in the foregoing embodiments, the principle and technical effects are described in the foregoing embodiments and will not be repeated here.

[0122] Optionally, in this embodiment of the application, the photodetector is used to receive light of a specific wavelength separated by the grating of the spectrometer in order to determine a certain component in the substance to be detected.

[0123] Based on the same inventive concept, embodiments of this application provide a method for manufacturing a photodetector, comprising:

[0124] Fabricating a sensing substrate comprising at least two sensing units includes: forming a thermoelectric conversion layer on one side of the substrate; forming a reflective electrode on one side of the thermoelectric conversion layer based on a patterning process; forming an elastic dielectric structure on one side of the reflective electrode; forming a light-transmitting electrode on one side of the elastic dielectric structure based on a patterning process; and forming a nanoparticle layer comprising at least two metal nanoparticles on one side of the light-transmitting electrode.

[0125] The superlens substrate is attached to the light-incident side of the sensing substrate, so that the light incident on the superlens unit in the superlens substrate is focused onto the absorption layer of the sensing unit, so that the absorption layer converts the light into heat energy and conducts it to the thermoelectric conversion layer. The thermoelectric conversion layer is configured to convert heat energy into electrical signals.

[0126] To facilitate readers' intuitive understanding of the fabrication method of the photodetector provided in the embodiments of this application, and the advantages of the photodetector fabricated using this method, the following will combine... Figures 12a-13c Please provide a detailed explanation.

[0127] In this embodiment of the application, the fabrication of the sensing substrate includes the following steps:

[0128] First, aluminum nitride material is deposited on one side of substrate 113 to form a thermoelectric conversion layer 112, such as... Figure 12a As shown.

[0129] Then, a reflective electrode 1111 is formed on one side of the thermoelectric conversion layer 112 using a patterning process. Specifically, this includes: depositing gold on the thermoelectric conversion layer 112 to form a first electrode layer; processing the first electrode layer through spin coating, exposure, development, and wet etching processes to obtain the reflective electrode 1111. Figure 12b As shown.

[0130] Next, PMMA material is deposited over the entire surface using electron beam evaporation to obtain the elastic dielectric structure 1112. This ensures uniform film formation of the elastic dielectric structure 1112. The elastic dielectric structure 1112 covers the areas of the reflective electrode 1111 and the thermoelectric conversion layer 112 not covered by the reflective electrode 1111, such as... Figure 12c As shown.

[0131] Then, a light-transmitting electrode 1113 is formed on one side of the elastic dielectric structure 1112 based on a patterning process. The material of the light-transmitting electrode 1113 includes ITO (Indium Tin Oxide), and its specific fabrication method is described in the fabrication method of the reflective electrode 1111.

[0132] Next, a spin-coating process is used to form a nanoparticle layer including metal nanoparticles 1114 in the areas of the transparent electrode 1113 and the elastic dielectric structure 1112 not covered by the transparent electrode 1113, such as... Figure 12d As shown.

[0133] In this embodiment of the application, the fabrication of the superlens substrate includes the following steps:

[0134] First, titanium dioxide is deposited on one side of the light-transmitting substrate 211 using an ALD (Atomic Layer Deposition) process to form an initial layer 201, such as... Figure 13a As shown.

[0135] Then, a photoresist layer 202 is formed on the initial layer 201 by spin coating, such as... Figure 13b As shown. Next, the initial layer 201 is patterned using nanoimprint lithography, and other parts are etched away to form multiple columnar structures 212 arranged on one side of the light-transmitting substrate 211, as shown. Figure 13c As shown.

[0136] In this application, the fabrication process of the sensing substrate and the fabrication process of the superlens substrate can be carried out simultaneously or sequentially. After both the sensing substrate and the superlens substrate are fabricated, a connecting layer 30 is fabricated on one side of the sensing substrate or the superlens substrate, and then the sensing substrate and the superlens substrate are bonded together.

[0137] By applying the embodiments of this application, at least the following beneficial effects can be achieved:

[0138] 1. In the photodetector provided in this application embodiment, by providing a superlens substrate 20 on the light-incident side of the sensing substrate, the superlens unit 21 focuses the incident light onto the absorption layer 111 of the sensing unit 11 in the sensing substrate. The absorption layer 111 converts the light into heat energy, and the thermoelectric conversion layer 112 converts the heat energy into an electrical signal, thus completing the detection of the incident light. In this way, the intensity and energy of the light incident on the sensing unit 11 can be increased by the superlens unit, and most of the energy from the light energy can be captured or absorbed by the absorption layer 111 and converted into energy form, thereby improving the sensitivity of the photodetector in detecting the incident light.

[0139] 2. In this embodiment of the application, the photoelectric sensor adopts a superlens substrate 20. Since the superlens unit 21 has the characteristics of small size and high planarity compared with the geometric optical lens, the size of the photoelectric sensor can be reduced, which is beneficial to the thinning of the spectrometer.

[0140] Those skilled in the art will understand that the steps, measures, and solutions in the various operations, methods, and processes discussed in this application can be alternated, modified, combined, or deleted. Furthermore, other steps, measures, and solutions in the various operations, methods, and processes discussed in this application can also be alternated, modified, rearranged, decomposed, combined, or deleted. Furthermore, steps, measures, and solutions in the prior art that are similar to those disclosed in this application can also be alternated, modified, rearranged, decomposed, combined, or deleted.

[0141] In the description of this application, the terms "center," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicate directions or positional relationships based on the exemplary directions or positional relationships shown in the accompanying drawings. They are used to facilitate the description or simplification of the embodiments of this application and are not intended to indicate or imply that the device or component referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0142] The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, unless otherwise stated, "a plurality of" means two or more.

[0143] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0144] In the description of this specification, specific features, structures, materials, or characteristics may be combined in any suitable manner in one or more embodiments or examples.

[0145] It should be understood that although the steps in the flowcharts of the accompanying drawings are shown sequentially according to the arrows, the order in which these steps are implemented is not limited to the order indicated by the arrows. Unless explicitly stated herein, in some implementation scenarios of this application, the steps in each process can be executed in other orders as required. Moreover, some or all of the steps in each flowchart may include multiple sub-steps or multiple stages based on the actual implementation scenario. Some or all of these sub-steps or stages may be executed at the same time or at different times. In scenarios where the execution times are different, the execution order of these sub-steps or stages can be flexibly configured according to requirements, and this application does not limit this.

[0146] The above description is only a partial embodiment of this application. It should be noted that for those skilled in the art, other similar implementation methods based on the technical concept of this application, without departing from the technical concept of this application, also fall within the protection scope of the embodiments of this application.

Claims

1. A photodetector, characterized in that, include: Sensing substrate and superlens substrate disposed on the light incident side of sensing substrate; The sensing substrate includes at least two sensing units, and the sensing unit includes a stacked absorption layer and a thermoelectric conversion layer; The superlens substrate includes at least two superlens units, each superlens unit being configured to focus incident light onto the absorption layer corresponding to the sensing unit, such that the absorption layer converts the light into heat energy and conducts it to the thermoelectric conversion layer, which is configured to convert the heat energy into an electrical signal. The absorption layer includes: a reflective electrode, an elastic dielectric structure, a light-transmitting electrode, and a nanoparticle layer, which are sequentially stacked on one side of the thermoelectric conversion layer, and the nanoparticle layer includes at least two metal nanoparticles; The elastic dielectric structure varies along a dimension perpendicular to the thermoelectric conversion layer as the electric field applied to the reflective electrode and the light-transmitting electrode changes.

2. The photodetector of claim 1, wherein, The elastic medium structure has a dimension perpendicular to the thermoelectric conversion layer that is not less than 4 nanometers and not more than 20 nanometers.

3. The photodetector of claim 2, wherein, As the elastic medium structure changes along the dimension perpendicular to the thermoelectric conversion layer, the absorption spectrum of the sensing unit is not less than 400 nm and not greater than 750 nm.

4. The photodetector of claim 1, wherein, It also includes at least one of the following: The diameter of the metal nanoparticles is not less than 45 nanometers and not more than 65 nanometers. The metal nanoparticles have a dimension perpendicular to the thermoelectric conversion layer that is not less than 50 nanometers and not more than 80 nanometers.

5. The photodetector of claim 1, wherein, The material of the reflective electrode includes any one of gold, silver, and aluminum.

6. The photodetector of claim 1, wherein, The superlens unit includes a light-transmitting substrate and at least two columnar structures of different diameters disposed on one side of the light-transmitting substrate; Along the direction from the center of the light-transmitting substrate to the edge, the diameter of each of the columnar structures gradually decreases.

7. The photodetector of claim 6, wherein, The plurality of columnar structures form at least two concentric columnar structure ring groups, wherein the diameters of the columnar structures in the same columnar structure ring group are all equal; In any two adjacent columnar ring groups, the diameter of the columnar structure in the outer columnar ring group is smaller than the diameter of the columnar structure in the inner columnar ring group.

8. The photodetector of claim 6, wherein, In the same superlens unit, all the columnar structures have the same size along the direction perpendicular to the light-transmitting substrate.

9. The photodetector of claim 6, wherein, It also includes at least one of the following: The columnar structure has a dimension of not less than 400 nanometers and not greater than 1 micrometer along the direction perpendicular to the light-transmitting substrate; The diameter of the columnar structure is not less than 40 nanometers and not more than 200 nanometers.

10. The photodetector of claim 1, wherein, Also includes: A connection layer disposed between the sensing substrate and the superlens substrate; The thickness of the connecting layer is less than the focal length of the superlens unit.

11. A spectrometer, characterized by, include: The photodetector as described in any one of claims 1-10.

12. A method of fabricating a photodetector as claimed in any one of claims 1-10, wherein, include: Fabricating a sensing substrate including at least two sensing units includes: forming a thermoelectric conversion layer on one side of the substrate, forming a reflective electrode on one side of the thermoelectric conversion layer based on a patterning process, forming an elastic dielectric structure on one side of the reflective electrode, forming a light-transmitting electrode on one side of the elastic dielectric structure based on a patterning process, and forming a nanoparticle layer including at least two metal nanoparticles on one side of the light-transmitting electrode. The superlens substrate is attached to the light-incoming side of the sensing substrate, so that the light rays incident to the superlens unit in the superlens substrate are focused to the absorbing layer of the sensing unit, so that the absorbing layer converts the light rays into heat energy and conducts to the thermoelectric conversion layer, which is configured to convert the heat energy into an electrical signal.

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