Preparation method of infrared polarization device and infrared polarization device

Abstract

The present disclosure relates to a method for preparing an infrared polarization device and an infrared polarization device, the preparation method comprising: providing a substrate; forming a first electrode on one side of the substrate; forming a first quantum dot detection structure having a preset concave-convex pattern on a side of the first electrode away from the substrate; the first quantum dot detection structure is physically formed; depositing a grating array structure on a side of the first quantum dot detection structure away from the first electrode; wherein the grating array structure is reused as a second electrode. In this way, by depositing the grating array structure on the first quantum dot detection structure having the preset concave-convex pattern, the chemical properties of the first quantum dot detection structure will not be damaged, which is conducive to improving the polarization detection performance of the infrared polarization device.

Description

Technical Field

[0001] The present disclosure relates to the field of infrared detection technology, and in particular to a method for preparing an infrared polarization device and an infrared polarization device. Background Art

[0002] At present, infrared imaging technology has attracted much attention due to its excellent performance such as long detection distance, high detection sensitivity and ability to work at night, and is usually used in combination with other technologies to expand its uses. For example, since different objects or the same object will produce different polarization states, by combining polarization technology with infrared imaging technology, it is possible to easily identify the target object in a complex background.

[0003] In infrared polarization imaging technology, polarizers such as gratings are responsible for identifying the polarization information of the target object, and together with colloidal quantum dots, they constitute an indispensable component of infrared polarization devices. However, existing infrared polarization imaging technology usually uses photolithography to prepare polarizers on the surface of colloidal quantum dots. This method applied to the surface of colloidal quantum dots will inevitably damage the chemical properties of the quantum dots, thereby reducing the polarization detection performance of infrared polarization devices. Summary of the invention

[0004] In order to solve the above technical problem or at least partially solve the above technical problem, the present disclosure provides a method for preparing an infrared polarization device and an infrared polarization device.

[0005] The present disclosure provides a method for preparing an infrared polarization device, comprising:

[0006] Providing a substrate; a first electrode is formed on one side of the substrate;

[0007] A first quantum dot detection structure having a preset concave-convex pattern is formed on a side of the first electrode away from the substrate; the first quantum dot detection structure is physically formed;

[0008] Depositing a grating array structure on a side of the first quantum dot detection structure away from the first electrode;

[0009] Wherein, the grating array structure is multiplexed as a second electrode.

[0010] Optionally, it also includes:

[0011] An N-type doped layer, an intrinsic quantum dot layer, and a P-type doped layer are sequentially formed on a side of the grating array structure away from the first quantum dot detection structure to obtain a second quantum dot detection structure;

[0012] A third electrode is deposited on a side of the second quantum dot detection structure away from the grating array structure.

[0013] Optionally, forming a first quantum dot detection structure having a preset concave-convex pattern on a side of the first electrode facing away from the substrate comprises:

[0014] Forming an N-type doped layer and an intrinsic quantum dot layer in sequence on a side of the first electrode away from the substrate by a spin coating or spray coating process;

[0015] Performing an imprint process on the intrinsic quantum dot layer by using a nanoimprint process to form the intrinsic quantum dot layer having a preset concave-convex pattern;

[0016] A P-type doping layer is formed on a side of the intrinsic quantum dot layer away from the N-type doping layer by using a spin coating or spray coating process.

[0017] The present disclosure also provides an infrared polarization device, comprising:

[0018] substrate;

[0019] A first electrode is disposed on one side of the substrate;

[0020] A first quantum dot detection structure is arranged on a side of the first electrode away from the substrate; the first quantum dot detection structure has a preset concave-convex pattern and is physically formed;

[0021] A grating array structure, arranged on a side of the first quantum dot detection structure away from the first electrode;

[0022] Wherein, the grating array structure is multiplexed as a second electrode.

[0023] Optionally, the infrared polarization device further comprises:

[0024] A second quantum dot detection structure is arranged on a side of the grating array structure away from the first quantum dot detection structure;

[0025] The third electrode is arranged on a side of the second quantum dot detection structure away from the grating array structure.

[0026] Optionally, the second quantum dot detection structure and the first quantum dot detection structure both include:

[0027] An N-type doped layer, an intrinsic quantum dot layer, and a P-type doped layer are sequentially stacked along a direction from the first electrode to the third electrode.

[0028] Optionally, the thickness of the N-type doping layer is: 10nm~50nm;

[0029] The thickness of the intrinsic quantum dot layer is 400nm-500nm;

[0030] The thickness of the P-type doping layer is 10nm-50nm.

[0031] Optionally, the grating array structure comprises grating units arranged in an array, and along a direction perpendicular to the plane where the substrate is located, each of the grating units comprises grating lines alternately arranged at a first height and a second height;

[0032] A preset number of adjacent grating units form a grating group; the grating lines of the grating units in the same grating group extend in different directions; and the grating units with different grating line extension directions are used to transmit infrared light with different polarization directions.

[0033] Optionally, the extension directions of the grating lines of the grating units of the same grating group are sequentially spaced at the same angle.

[0034] Optionally, the substrate includes a signal readout circuit; the signal readout circuit includes pixel areas arranged in an array;

[0035] The vertical projection of the grating unit on the substrate corresponds to the pixel area one by one.

[0036] Compared with the prior art, the technical solution provided by the embodiments of the present disclosure has the following advantages:

[0037] The method for preparing an infrared polarization device provided by the embodiment of the present disclosure includes: providing a substrate; forming a first electrode on one side of the substrate; forming a first quantum dot detection structure having a preset concave-convex pattern on the side of the first electrode away from the substrate; the first quantum dot detection structure is physically formed; depositing a grating array structure on the side of the first quantum dot detection structure away from the first electrode; wherein the grating array structure is reused as a second electrode. In this way, by depositing the grating array structure on the first quantum dot detection structure having the preset concave-convex pattern, the chemical properties of the first quantum dot detection structure will not be damaged, which is conducive to improving the polarization detection performance of the infrared polarization device. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present disclosure and, together with the description, serve to explain the principles of the present disclosure.

[0039] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0040] Figure 1 A schematic flow chart of a method for preparing an infrared polarization device provided in an embodiment of the present disclosure;

[0041] Figure 2 A schematic diagram of a process flow of an imprinting process for an intrinsic quantum dot layer provided in an embodiment of the present disclosure;

[0042] Figure 3 A schematic diagram of the structure of an infrared polarization device provided in an embodiment of the present disclosure;

[0043] Figure 4 A schematic structural diagram of another infrared polarization device provided in an embodiment of the present disclosure;

[0044] Figure 5 A schematic structural diagram of another infrared polarization device provided in an embodiment of the present disclosure;

[0045] Figure 6 A schematic structural diagram of another infrared polarization device provided in an embodiment of the present disclosure;

[0046] Figure 7 A schematic diagram of a grating array structure provided in an embodiment of the present disclosure;

[0047] Figure 8 A schematic diagram of the arrangement structure of a grating unit provided in an embodiment of the present disclosure.

[0048] Among them, 01, N-type doped layer; 02, intrinsic quantum dot layer; 03, P-type doped layer; 210, substrate; 220, first electrode; 230, first quantum dot detection structure; 240, grating array structure; 241, grating unit; 2411, grating line; 250, second quantum dot detection structure; 260, third electrode. DETAILED DESCRIPTION

[0049] In order to more clearly understand the above-mentioned objectives, features and advantages of the present disclosure, the scheme of the present disclosure will be further described below. It should be noted that the embodiments of the present disclosure and the features in the embodiments can be combined with each other without conflict.

[0050] In the following description, many specific details are set forth to facilitate a full understanding of the present disclosure, but the present disclosure may also be implemented in other ways different from those described herein; it is obvious that the embodiments in the specification are only part of the embodiments of the present disclosure, rather than all of the embodiments.

[0051] First, in combination with the relevant background, the defects of the prior art and the improvements of the present application are explained.

[0052] In the field of infrared detection technology, infrared imaging technology has expanded the scope of objective information that people can observe, surpassing the limitations of visible light imaging, and has been widely used in military, security, fire protection, aerospace, medical and other fields. However, traditional infrared detectors are constrained by complex molecular beam epitaxial growth and flip-chip bonding processes, resulting in high manufacturing costs. In order to break through the above bottlenecks, people have conducted relevant research on the preparation of materials. Among them, colloidal quantum dots have become an ideal choice for infrared applications because of their unique properties, such as tunable size-dependent optical properties and easy processing.

[0053] As infrared imaging technology continues to develop, it is often used in combination with other technologies to expand its uses. For example, taking polarization technology as an example, polarization is an important property of light waves, which is completely independent of amplitude, phase and frequency. When light interacts with an object, the inherent properties of the object, such as surface roughness, shape and material, will give the light wave a specific polarization state. Taking advantage of this property, polarization technology can be used to detect the characteristic polarization signal of the object in a complex environment, such as a background similar to the target, and reveal the hidden target through imaging.

[0054] In infrared polarization imaging systems, polarizers play a key role. They are responsible for identifying the polarization information of the object being measured and are an indispensable part of the system. As miniaturization, micro-miniaturization, and even integration of infrared polarization imaging systems become the main development trend, traditional infrared polarizers are no longer applicable. How to prepare smaller polarizers has become the focus of research.

[0055] In recent years, researchers have successfully prepared smaller polarizers, namely nano-grating structures, using a variety of micro-nano processing techniques. As a new type of device with small size and strong adaptability, it has shown good replacement potential. However, this nano-grating structure is mainly prepared on one side of colloidal quantum dots using photolithography. Since this method usually involves photochemical reactions, its application on the surface of colloidal quantum dots will inevitably damage the chemical properties of the quantum dots, thereby reducing the polarization detection performance of infrared polarization devices.

[0056] In response to at least one of the above problems, an embodiment of the present disclosure provides a method for preparing an infrared polarization device. By depositing a grating array structure on a first quantum dot detection structure with a preset concave-convex pattern, damage to the chemical properties of the quantum dots caused by the photolithography process is avoided, the stability of the chemical properties of the first quantum dot detection structure is ensured, and the polarization detection performance of the infrared polarization device is improved.

[0057] The preparation method of the infrared polarization device and the infrared polarization device provided in the embodiments of the present disclosure are exemplarily described below with reference to the accompanying drawings.

[0058] Figure 1A schematic diagram of a method for preparing an infrared polarization device provided in an embodiment of the present disclosure. Figure 1 , the method comprising:

[0059] S110, providing a substrate.

[0060] A first electrode is formed on one side of the substrate.

[0061] Exemplarily, acetone, isopropyl alcohol and deionized water can be used to clean the substrate in sequence; in addition, the first electrode can be one or more of indium tin oxide (ITO), indium zinc oxide (IZO), and indium oxide (In2O3), and its thickness can be 20nm~100nm. It is prepared by physical vapor deposition (PVD) such as magnetron sputtering and thermal evaporation, or chemical vapor deposition (CVD). In other embodiments, it can also be other electrode materials, thicknesses and electrode formation methods known to those skilled in the art, which are not limited here.

[0062] S120, forming a first quantum dot detection structure having a preset concave-convex pattern on a side of the first electrode facing away from the substrate.

[0063] Specifically, compared with the adverse effects on quantum dots caused by the photolithography process to form a preset concave-convex pattern, the first quantum dot detection structure of the embodiment of the present disclosure is prepared by adopting a physical molding technology to obtain a preset concave-convex pattern, which will not cause adverse effects on quantum dots, such as damaging their chemical properties, and can be applied to a variety of material systems, with good application prospects.

[0064] The first quantum dot detection structure includes a convex structure arranged at intervals, and a concave structure is provided between two adjacent convex structures, thereby forming a concave-convex pattern. It should be noted that the convex structure is in the shape of a strip, and the extension direction of the convex structure can be set according to the preparation requirements of the infrared polarization device, such as: relative to a certain reference direction, the extension direction of the convex structure can be 0°, 22.5°, 45° or other angles, which are not limited here.

[0065] S130, depositing a grating array structure on a side of the first quantum dot detection structure away from the first electrode.

[0066] Among them, the grating array structure is reused as the second electrode. Specifically, physical vapor deposition, chemical vapor deposition or other deposition processes can be used to vertically deposit corresponding grating lines at the convex structure and the concave structure of the first quantum dot detection structure to obtain a grating array structure; compared with the prior art that uses a photolithography process to prepare a grating array structure on one side of the quantum dot, the embodiment of the present disclosure avoids the adverse effects of the photochemical reaction in the photolithography process on the quantum dot, ensures the stability of the chemical properties of the first quantum dot detection structure, and has a simple preparation process. In addition, there is no connection between the grating lines formed thereby, which can reduce unnecessary material consumption and help reduce preparation costs.

[0067] In addition, the preparation materials of the grating array structure include but are not limited to conductive materials such as metals. Taking metal materials as an example, the grating array structure can be prepared from metal materials such as aluminum, gold, silver, and chromium. The type of metal material can be selected according to the polarization performance requirements of the infrared polarization device, and is not limited here.

[0068] The method for preparing an infrared polarization device provided by the embodiment of the present disclosure includes: providing a substrate; forming a first electrode on one side of the substrate; forming a first quantum dot detection structure having a preset concave-convex pattern on the side of the first electrode away from the substrate; the first quantum dot detection structure is physically formed; depositing a grating array structure on the side of the first quantum dot detection structure away from the first electrode; wherein the grating array structure is reused as a second electrode. In this way, by depositing the grating array structure on the first quantum dot detection structure having the preset concave-convex pattern, the chemical properties of the first quantum dot detection structure will not be damaged, which is conducive to improving the polarization detection performance of the infrared polarization device.

[0069] In some embodiments, Figure 1 On the basis of, the preparation method also includes the following steps:

[0070] Step 1: An N-type doped layer, an intrinsic quantum dot layer and a P-type doped layer are sequentially formed on a side of the grating array structure away from the first quantum dot detection structure to obtain a second quantum dot detection structure.

[0071] Specifically, the N-type doped layer, the intrinsic quantum dot layer and the P-type doped layer can be stacked in sequence. For example, the above film layers can be formed by spin coating or spraying. In other embodiments, the second quantum dot detection structure can also be prepared by other methods known to those skilled in the art, which are not limited here.

[0072] Exemplarily, the material for preparing the intrinsic quantum dot layer may be mercury sulfide (HgS2), mercury selenide (HgSe), indium antimonide (InSb), lead selenide (PbSe) or mercury telluride (HgTe), the material for preparing the N-type doping layer may be ZnO (zinc oxide), bismuth sulfide (Bi2S3), or one of the N-type quantum dots that are the same as the intrinsic quantum dots, and the material for preparing the P-type doping layer may be molybdenum trioxide (MoO3), silver telluride (Ag2Te), or one of the P-type quantum dots that are the same as the intrinsic quantum dots.

[0073] In other embodiments, an electron transport layer may be provided between the grating array structure and the N-type doped layer, and its preparation material may be zinc oxide (ZnO), titanium dioxide (TiO2) or methyl butyrate (PCBM). Furthermore, a hole transport layer may be formed above the P-type doped layer, and its preparation material may be polystyrene sulfonate (PEDOT:PSS), molybdenum oxide (MoOx) or butylphenyl-N,N″-biphenyl (PolyTPD), which are not limited here.

[0074] Step 2: depositing a third electrode on a side of the second quantum dot detection structure away from the grating array structure.

[0075] Exemplarily, the third electrode may be gold, aluminum, silver or nickel, and its thickness may be 20nm~100nm, and it is prepared by magnetron sputtering, thermal evaporation or electron beam evaporation. In other embodiments, it may also be other electrode materials, thicknesses and electrode formation methods known to those skilled in the art, which are not limited here.

[0076] In some embodiments, Figure 1 Based on this, S120 includes the following steps:

[0077] Step 1: Using a spin coating or spray coating process, an N-type doped layer and an intrinsic quantum dot layer are sequentially formed on a side of the first electrode away from the substrate.

[0078] Specifically, by using a spin coating or spray coating process to sequentially form the above film layers, the thickness of the corresponding film layers can be accurately controlled, so that the N-type doped layer and the intrinsic quantum dot layer have good thickness uniformity, ensuring the film quality. In addition, the preparation materials of the N-type doped layer and the intrinsic quantum dot layer in the first quantum dot detection structure and the second quantum dot detection structure can be the same, which will not be repeated here.

[0079] Step 2: Use a nanoimprint process to perform an imprint process on the intrinsic quantum dot layer to form an intrinsic quantum dot layer with a preset concave-convex pattern.

[0080] For example, Figure 2 A schematic diagram of a process flow of an imprinting process of an intrinsic quantum dot layer provided in an embodiment of the present disclosure. Figure 2 A nanoimprint mold having a preset concave-convex pattern can be prepared first, and then the prepared nanoimprint mold is brought into contact with the intrinsic quantum dot layer and a preset pressure is applied, such as 20MPa~70MPa. The preset concave-convex pattern on the nanoimprint mold can be imprinted on the surface of the intrinsic quantum dot layer, that is, S134, to achieve precise transfer of the preset concave-convex pattern. The size of the applied pressure can be set according to the preparation requirements of the infrared polarization device, and is not limited here.

[0081] Exemplarily, the preparation process of the nanoimprint mold may specifically include: using a spin coating process to coat a photoresist onto a substrate surface, i.e., S131, and then placing the substrate coated with the photoresist on a hot plate for baking for a certain period of time to remove solvent components such as water in the photoresist, thereby improving the contact strength between the substrate and the photoresist and preparing for making a concave-convex pattern thereon; then irradiating the photoresist with ultraviolet light, focusing the ultraviolet light on the surface of the photoresist through a mask for exposure, and forming an initial concave-convex pattern, i.e., S132; on this basis, developing and etching the exposed photoresist to form a desired preset concave-convex pattern on the substrate, i.e., S133.

[0082] Step 3: Use a spin coating or spray coating process to form a P-type doping layer on the side of the intrinsic quantum dot layer away from the N-type doping layer.

[0083] It should be noted that the thickness of the P-type doped layer is relatively thin. If an N-type doped layer, an intrinsic quantum dot layer and a P-type doped layer are formed in sequence above the first electrode, and an embossing process is performed above the P-type doped layer to form a preset concave-convex pattern, defects may appear in certain areas of the P-type doped layer, thereby destroying the integrity of the film layer. The embodiment of the present disclosure forms a preset concave-convex pattern on the surface of the intrinsic quantum dot layer, and then forms the P-type doped layer from above by spin coating or spraying. This can ensure the uniformity and integrity of the P-type doped layer, which is beneficial for the infrared polarization device to form a good detection effect.

[0084] For example, continue to refer to Figure 2 After forming the P-type doping layer, metal can be deposited on the P-type doping layer, that is, S135, so that a grating array structure can be obtained, which significantly reduces the process difficulty and cost of the grating array structure.

[0085] The nanoimprint process provided by the embodiment of the present disclosure adopts a mold replication method, which can quickly and massively produce structures with nanoscale features, such as the first quantum dot detection structure, further improving the production efficiency of the grating array structure. The nanoimprint mold can be reused, which greatly reduces the cost of the nanoimprint process and is suitable for large-scale production.

[0086] On the basis of the above-mentioned embodiments, an embodiment of the present disclosure further provides an infrared polarization device, which is prepared based on any one of the preparation methods of the infrared polarization device provided in the above-mentioned embodiments.

[0087] In some embodiments, Figure 3 This is a schematic diagram of the structure of an infrared polarization device provided by an embodiment of the present disclosure. Figure 3 The infrared polarization device includes: a substrate 210; a first electrode 220, which is arranged on one side of the substrate 210; a first quantum dot detection structure 230, which is arranged on the side of the first electrode 220 away from the substrate 210; the first quantum dot detection structure 230 has a preset concave-convex pattern and is physically formed; a grating array structure 240, which is arranged on the side of the first quantum dot detection structure 230 away from the first electrode 220; wherein the grating array structure 240 is reused as a second electrode.

[0088] The substrate 210 is a substrate for carrying structures such as the first electrode 220, the first quantum dot detection structure 230, and the grating array structure 240. For example, the substrate 210 may be a silicon-based readout circuit substrate or other types of substrates for detecting imaging, which are not limited here.

[0089] The grating array structure 240 is used to transmit infrared light with different polarization directions, which depends on the extension direction of the grating lines in the grating array structure 240, that is, the extension direction of the grating lines is different, and the polarization direction of the transmitted infrared light is also different. Based on this, the extension direction of the grating lines in the grating array structure 240 may include multiple directions to transmit infrared light with different polarization directions, thereby improving the imaging efficiency. The correlation between the extension direction of the grating lines and the polarization direction of the transmitted infrared light will be exemplarily described later.

[0090] Among them, the first quantum dot detection structure 230 is used to perform photoelectric response to polarized infrared light. Specifically, the first quantum dot detection structure 230 absorbs infrared light of different polarization directions emitted from the grating array structure 240, and performs photoelectric response based on the infrared light, that is, converts infrared light signals of different polarization directions into corresponding electrical signals, so that subsequent related circuits can perform infrared polarization imaging through the electrical signals. The specific principle of infrared polarization imaging is exemplified later.

[0091] It is not difficult to understand that by reusing the grating array structure 240 as the second electrode, the number of film layers of the infrared polarization device can be reduced, thereby reducing the overall volume of the infrared polarization device and simplifying the film layer preparation process of the infrared polarization device. In this way, the miniaturized design of the infrared polarization device is achieved, the preparation efficiency is improved, and the overall application cost is saved.

[0092] Compared with the existing polarization infrared imaging technology, an infrared polarization device can only collect infrared images with different polarization directions in a time-sharing manner, resulting in the inability of the existing infrared polarization device to detect dynamic scenes in real time and accurately, or integrating multiple infrared polarization devices to collect infrared images with multiple polarization directions, resulting in the problem of an overall volume that is too large. The infrared polarization device provided in the embodiment of the present disclosure transmits infrared light with different polarization directions through the grating array structure 240, and can simultaneously collect infrared images with multiple polarization directions, thereby increasing the polarization characteristics of the infrared image and reducing image interference, thereby improving the real-time and accuracy of infrared image acquisition, facilitating real-time and accurate detection of dynamic scenes, and realizing the miniaturization design of the infrared polarization device.

[0093] In some embodiments, Figure 4 A schematic diagram of the structure of another infrared polarization device provided in an embodiment of the present disclosure. Figure 3 Based on Figure 4 The infrared polarization device also includes: a second quantum dot detection structure 250, which is arranged on a side of the grating array structure 240 away from the first quantum dot detection structure 230; and a third electrode 260, which is arranged on a side of the second quantum dot detection structure 250 away from the grating array structure 240.

[0094] Among them, the second quantum dot detection structure 250 is used to perform photoelectric response to non-polarized infrared light, that is, infrared light containing all polarization information, and in particular, the second quantum dot detection structure 250 has a preset transmittance for non-polarized infrared light, and can transmit a certain proportion of non-polarized infrared light, such as: its transmittance for non-polarized infrared light can be 60%, and the remaining 40% of non-polarized infrared light can be absorbed by the second quantum dot detection structure 250, or the transmittance of the second quantum dot detection structure 250 for non-polarized infrared light can also be 50%, 70% or other values, which is usually related to the thickness of the second quantum dot detection structure 250, and can be set according to the polarization imaging requirements of the infrared polarization device, which is not limited here.

[0095] Specifically, in practical applications, a portion of the non-polarized infrared light is absorbed by the second quantum dot detection structure 250, and an electrical signal for the non-polarized infrared light is generated based on the photoelectric response. Correspondingly, another portion of the non-polarized infrared light is selectively transmitted by the grating array structure 240, that is, the grating lines with different extension directions transmit infrared light with different polarization directions, and then the second quantum dot detection structure 250 is used to absorb infrared light with different polarization directions, and an electrical signal for polarized infrared light is generated based on the photoelectric response. In this way, polarization information and non-polarization information are collected simultaneously, and more comprehensive information about the object to be observed can be obtained, thereby improving the imaging quality.

[0096] In some embodiments, along a direction perpendicular to the plane of the substrate, a vertical projection of the first quantum dot detection structure coincides with a vertical projection of the second quantum dot detection structure.

[0097] In this way, by setting the vertical projections of the first quantum dot detection structure and the second quantum dot detection structure to overlap, it can be ensured that the second quantum dot detection structure completely covers the first quantum dot detection structure, so that each pixel area on the substrate can output polarization information and non-polarization information together, greatly improving the accuracy of target recognition.

[0098] In some embodiments, Figure 5 This is a schematic diagram of the structure of another infrared polarization device provided by an embodiment of the present disclosure. Figure 5 The second quantum dot detection structure 250 and the first quantum dot detection structure 230 both include: an N-type doped layer 01, an intrinsic quantum dot layer 02 and a P-type doped layer 03 which are sequentially stacked along the direction from the first electrode 220 to the third electrode 260.

[0099] It is not difficult to understand that, along the direction from the first electrode 220 to the third electrode 260, the second quantum dot detection structure 250 and the first quantum dot detection structure 230 form a photovoltaic infrared polarization device by providing a sequentially stacked N-type doped layer 01, an intrinsic quantum dot layer 02, and a P-type doped layer 03. In other embodiments, the second quantum dot detection structure 250 and the first quantum dot detection structure 230 may only include the intrinsic quantum dot layer 02 to form a photoconductive infrared polarization device.

[0100] Among them, the first electrode 220 is the bottom electrode of the infrared polarization device, which is used to collect electrons generated by the photoelectric response of the first quantum dot detection structure 230; the grating array structure 240 is multiplexed as the middle electrode of the infrared polarization device, which is used to collect holes generated by the photoelectric response of the first quantum dot detection structure 230, and / or electrons generated by the photoelectric response of the second quantum dot detection structure 250; the third electrode 260 is the top electrode of the infrared polarization device, which is used to collect holes generated by the photoelectric response of the second quantum dot detection structure 250.

[0101] Specifically, after external infrared light, such as anisotropic infrared light emitted by the object to be observed and ambient light, is transmitted by the top electrode, the second quantum dot detection structure 250 performs photoelectric response to a portion of the non-polarized infrared light to generate photogenerated carriers, namely electron-hole pairs. Since the intrinsic quantum dots are doped with N-type quantum dots and P-type quantum dots, the electrons and holes generated in the second quantum dot detection structure 250 diffuse unevenly, thereby forming a built-in potential, which dissociates into free electrons and holes under the action of the built-in potential, and then the holes and electrons move to the top electrode and the middle electrode, respectively. Similarly, after another portion of the non-polarized infrared light is selectively transmitted by the grating array structure 240, the first quantum dot detection structure 230 performs photoelectric response to infrared light of different polarization directions, and the generated holes and electrons move to the middle electrode and the bottom electrode, respectively.

[0102] It should be noted that the photovoltaic infrared polarization device formed in the embodiment of the present disclosure can work normally under a relatively low bias voltage (built-in potential) without the need for additional applied voltage, and has good instant response capability.

[0103] Compared with photoconductive infrared polarization devices, photogenerated carriers in photovoltaic infrared polarization devices can be directly separated under the action of built-in potential, which reduces the diffusion and recombination of photogenerated carriers, forms a good photoelectric response effect, and then improves the signal-to-noise ratio of related signals such as electrical signals, which is conducive to high-sensitivity infrared detection by infrared polarization devices.

[0104] In addition, the embodiment of the present disclosure can also apply voltage to the infrared polarization device through an external power supply to enhance the built-in potential formed by the second quantum dot detection structure 250 and the first quantum dot detection structure 230, increase the movement speed of electrons and holes, and drive electrons to move to the substrate 210 to form a directionally moving current, so as to collect and process the electrical signals in the current.

[0105] In some embodiments, continue to refer to Figure 5 The thickness of the N-type doping layer 01 is 10nm~50nm; the thickness of the intrinsic quantum dot layer 02 is 400nm~500nm; and the thickness of the P-type doping layer 03 is 10nm~50nm.

[0106] In this way, by setting the thickness of the N-type doped layer 01, the intrinsic quantum dot layer 02 and the P-type doped layer 03 to the above range, it is helpful for electrons and holes to move quickly in the corresponding directions, ensuring the transmission efficiency of electrons and holes, so that the photoelectric response of the infrared polarization device is stronger, which is conducive to forming a good detection effect. The specific values ​​of the thickness of the N-type doped layer 01, the intrinsic quantum dot layer 02 and the P-type doped layer 03 can be set according to the transmission requirements of electrons and holes, and are not limited here.

[0107] In some embodiments, Figure 6 A schematic diagram of the structure of another infrared polarization device provided in an embodiment of the present disclosure, Figure 7 A schematic diagram of a grating array structure provided by an embodiment of the present disclosure. Figure 6 and Figure 7 The grating array structure 240 includes grating units 241 arranged in an array, and along a direction perpendicular to the plane where the substrate 210 is located, each grating unit 241 includes grating lines 2411 alternately arranged at a first height and a second height; a preset number of adjacent grating units 241 form a grating group; the grating lines of each grating unit 241 in the same grating group extend in different directions; the grating units 241 with different grating line extension directions are used to transmit infrared light with different polarization directions.

[0108] The grating groups in the grating array structure 240 are arranged in an array, and the array arrangement of each grating unit 241 in each grating group is the same or different. Exemplarily, the grating units 241 in a grating group may be arranged in n rows and n columns, for example: 3 rows and 3 columns, 4 rows and 4 columns, etc., or in one row and n columns, for example: 1 row and 3 columns, 1 row and 5 columns, etc., or in n rows and m columns, where n and m are positive integers of different sizes, for example: 2 rows and 3 columns, 3 rows and 4 columns, etc. In other embodiments, the grating units 241 may be arranged in other ways known to those skilled in the art, which are not limited here.

[0109] In each grating unit 241, the grating lines 2411 alternately arranged at the first height and the second height are not connected and are parallel to each other. Figure 6 Taking the orientation and structure shown as an example, if the first quantum dot detection structure 230 is extended vertically upward from the bottom edge, the first height may be H1, the second height may be H2, and the first height is greater than the second height. In other embodiments, the first height may also be less than the second height. It is only necessary to ensure that the first height and the second height are different, and it is not limited here.

[0110] It should be noted that compared to the method of arranging the grating lines 2411 at intervals only at a single height, the embodiment of the present disclosure increases the effective area of ​​the grating lines 2411 by alternately arranging the grating lines 2411 at the first height and the second height, so that more polarized infrared light is transmitted, and the corresponding transmittance and extinction ratio are higher (see below), thereby improving the polarization effect of the grating array structure 240.

[0111] The extending direction of the grating lines of the grating unit 241 and the polarization direction of the infrared light have a one-to-one correspondence. For example, based on a certain reference direction, if the extending direction of the grating lines of a certain grating unit 241 is parallel to the reference direction, it can transmit infrared light with a polarization direction parallel to the reference direction; if the extending direction of the grating lines of a certain grating unit 241 is perpendicular to the reference direction, it can transmit infrared light with a polarization direction perpendicular to the reference direction. The specific corresponding relationship between the extending direction of the grating lines and the polarization direction of the infrared light will be described in detail later.

[0112] In some embodiments, the extending directions of the grating lines of each grating unit in the same grating group are sequentially spaced at the same angle.

[0113] For example, Figure 8 A schematic diagram of the arrangement structure of a grating unit provided in an embodiment of the present disclosure. Figure 8 , Figure 8 A grating group includes four grating units 241, and the grating lines of each grating unit 241 extend in directions 45° apart from each other. Figure 8 Taking the orientation in as an example, relative to the reference direction (such as the vertical direction Y), the extension directions of the grating lines of the four grating units 241 are 0°, 45°, 90° and 135°, respectively, indicating that the grating group can simultaneously transmit infrared light with four different polarization directions, corresponding to: infrared light with polarization directions of 0°, 45°, 90° and 135°, respectively. In this way, infrared images with four polarization characteristics can be collected simultaneously, thereby improving the imaging efficiency.

[0114] Exemplarily, the extension directions of the grating lines of each grating unit 241 of the same grating group may be sequentially spaced at intervals of 10°, 30° or other angles, as long as the interval angles are the same, which is not limited here.

[0115] In this way, by setting the grating line extension directions of each grating unit 241 of the same grating group to be spaced at the same angle in sequence, the grating line extension directions of each grating unit 241 are evenly spaced, and thus uniform polarization information can be collected through each grating unit 241 of the grating group, which is beneficial to improving the subsequent imaging quality to reflect the real information of the object to be observed.

[0116] In some embodiments, the period of the grating unit is 0.6 um to 1.0 um, and the duty cycle is 0.4 to 0.6.

[0117] Herein, the period represents the spacing between grating lines (in micrometers, nanometers or sub-nanometers), and the duty cycle represents the area ratio of the grating lines in the grating unit. In the embodiment of the present disclosure, the grating unit is a sub-wavelength grating, and its period and duty cycle both meet the sub-wavelength condition.

[0118] It should be noted that the infrared light includes TE polarized light parallel to the extension direction of the grating lines and TM polarized light perpendicular to the extension direction of the grating lines. The TE polarized light will excite the electrons on the grating lines to generate current, so that the TE polarized light is reflected by the grating unit, while the TM polarized light cannot induce current due to the isolation of the grating lines by air gaps. At this time, the TM polarized light can be transmitted through the grating unit.

[0119] It can be seen that the main parameters for measuring the polarization performance of the grating unit include transmittance and extinction ratio, among which: transmittance represents the percentage of TM polarized light passing through the grating unit, and extinction ratio represents the ratio of the transmittance of TM polarized light to the transmittance of TE polarized light. It is not difficult to know that, in theory, the higher the transmittance and extinction ratio, the better the polarization performance of the grating unit.

[0120] Among them, the period and duty cycle are important parameters that affect the polarization performance of the grating unit, and both can directly affect the optical response of the grating unit. Specifically, with respect to the duty cycle, under normal circumstances, the higher the duty cycle of the grating unit, the larger the area occupied by the grating lines, and the smaller the interval between the grating lines, so that the interaction between the grating lines is enhanced, so that the response of the grating unit to infrared light is enhanced, such as: the transmittance of the grating lines to TM polarized light can be increased, and the scattering efficiency of the grating lines to TE polarized light can be increased, and as more and more infrared light interacts with the grating unit, the efficiency of energy conversion is further increased; with respect to the period, a smaller period can produce a higher frequency response, so that the grating unit can transmit and refract higher frequency infrared light to form a high-resolution infrared polarization device and improve the quality of infrared polarization imaging.

[0121] Therefore, the embodiment of the present disclosure sets the period of the grating unit to 0.6um-1.0um and the duty cycle to 0.4-0.6, which can ensure that the grating unit has good polarization performance, thereby facilitating improving the quality of infrared polarization imaging.

[0122] In some embodiments, the grating lines of the grating unit are made of aluminum.

[0123] Among them, different types of metal materials have different effects on the transmittance and extinction ratio of the grating unit. By selecting aluminum as the preparation material for the grating lines, the transmittance and extinction ratio corresponding to the grating lines can be made higher, thereby ensuring that the grating unit has good polarization performance.

[0124] In some embodiments, the substrate includes a signal readout circuit; the signal readout circuit includes pixel regions arranged in an array; and a vertical projection of the grating unit on the substrate corresponds one-to-one to the pixel regions.

[0125] The substrate is provided with pixel electrodes arranged in an array, and the pixel electrodes are electrically connected to the first electrode. Specifically, the electrical signals in the first quantum dot detection structure and the second quantum dot detection structure are transmitted to the pixel electrodes at different positions through the first electrode, and then the electrical signals are converted into digital signals and read out through the signal readout circuit, and then the digital signals are output to the external related circuit to detect imaging.

[0126] Exemplarily, based on the arrangement of the grating unit array, the vertical projection of each grating unit on the substrate is located in the corresponding pixel area, and the vertical projection area of ​​each grating unit on the substrate is equal, such as: the vertical projection area of ​​each grating unit on the substrate can be less than or equal to the area of ​​the corresponding pixel area. In this way, on the basis of improving the integration between the grating units, crosstalk between the corresponding infrared lights transmitted by each grating unit can be avoided, so as to improve the accuracy of polarization information collected by the infrared polarization device.

[0127] Illustratively, the infrared polarization device provided in the embodiments of the present disclosure may be an optoelectronic imaging device integrated with a complementary metal oxide semiconductor (CMOS) image sensor, wherein the actual size of each grating unit matches the pixel size of the CMOS image sensor, and each grating unit corresponds one-to-one to the pixel size of the intrinsic quantum dot layer, so that infrared light emitted from each grating unit can be collected and processed in different regions, thereby improving the accuracy of infrared image collection.

[0128] In some embodiments, the infrared polarization device further includes a data acquisition module and a data analysis and imaging system.

[0129] The data acquisition module is used to acquire the digital signal output by the signal readout circuit, and the data analysis and imaging system is used to analyze the digital signal and perform infrared polarization imaging. Specifically, the data analysis and imaging system can integrate the digital signal acquired by the data acquisition module, analyze and process the digital signal, and then perform detection imaging based on the results of the analysis and processing to obtain a polarization imaging image of the object to be observed in the target band. Exemplarily, the target band can be at least one of short-wave infrared, medium-wave infrared, and long-wave infrared, which is not limited here.

[0130] It should be noted that, in this article, relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.

[0131] The above description is only a specific embodiment of the present disclosure, so that those skilled in the art can understand or implement the present disclosure. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present disclosure. Therefore, the present disclosure will not be limited to the embodiments described herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing an infrared polarization device, characterized in that: include: providing a substrate; A first electrode is formed on one side of the substrate; A first quantum dot detection structure having a preset concave-convex pattern is formed on a side of the first electrode away from the substrate; the first quantum dot detection structure is physically formed; Depositing a grating array structure on a side of the first quantum dot detection structure away from the first electrode; Wherein, the grating array structure is multiplexed as a second electrode; The method further includes: sequentially forming an N-type doped layer, an intrinsic quantum dot layer, and a P-type doped layer on a side of the grating array structure away from the first quantum dot detection structure to obtain a second quantum dot detection structure; wherein the second quantum dot detection structure is used to perform a photoelectric response to non-polarized infrared light, and has a preset transmittance to the non-polarized infrared light; The first quantum dot detection structure having a preset concave-convex pattern is formed on a side of the first electrode away from the substrate, comprising: Forming an N-type doped layer and an intrinsic quantum dot layer in sequence on a side of the first electrode away from the substrate by a spin coating or spray coating process; Performing an imprint process on the intrinsic quantum dot layer by using a nanoimprint process to form the intrinsic quantum dot layer having a preset concave-convex pattern; A P-type doping layer is formed on a side of the intrinsic quantum dot layer away from the N-type doping layer by using a spin coating or spray coating process.

2. The method for preparing an infrared polarization device according to claim 1, characterized in that: Also includes: A third electrode is deposited on a side of the second quantum dot detection structure away from the grating array structure.

3. An infrared polarization device, characterized in that: include: substrate; A first electrode is disposed on one side of the substrate; A first quantum dot detection structure is disposed on a side of the first electrode away from the substrate; The first quantum dot detection structure has a preset concave-convex pattern and is physically formed; A grating array structure, arranged on a side of the first quantum dot detection structure away from the first electrode; Wherein, the grating array structure is multiplexed as a second electrode; It also includes: a second quantum dot detection structure, which is arranged on a side of the grating array structure away from the first quantum dot detection structure; the second quantum dot detection structure includes an N-type doped layer, an intrinsic quantum dot layer and a P-type doped layer which are sequentially stacked on a side of the grating array structure away from the first quantum dot detection structure; The first quantum dot detection structure includes: an N-type doped layer and an intrinsic quantum dot layer formed in sequence on a side of the first electrode away from the substrate, and a P-type doped layer formed on a side of the intrinsic quantum dot layer away from the N-type doped layer; the intrinsic quantum dot layer has a preset concave-convex pattern.

4. The infrared polarization device according to claim 3, characterized in that: Also includes: The third electrode is arranged on a side of the second quantum dot detection structure away from the grating array structure.

5. The infrared polarization device according to claim 3, characterized in that: The thickness of the N-type doping layer is: 10nm~50nm; The thickness of the intrinsic quantum dot layer is 400nm-500nm; The thickness of the P-type doping layer is 10nm-50nm.

6. The infrared polarization device according to claim 3, characterized in that: The grating array structure comprises grating units arranged in an array, and along a direction perpendicular to the plane where the substrate is located, each of the grating units comprises grating lines alternately arranged at a first height and a second height; A preset number of adjacent grating units form a grating group; the grating lines of the grating units in the same grating group extend in different directions; and the grating units with different grating line extension directions are used to transmit infrared light with different polarization directions.

7. The infrared polarization device according to claim 6, characterized in that: The extending directions of the grating lines of the grating units of the same grating group are sequentially spaced at the same angle.

8. The infrared polarization device according to claim 6, characterized in that: The substrate includes a signal readout circuit; the signal readout circuit includes pixel areas arranged in an array; The vertical projection of the grating unit on the substrate corresponds to the pixel area one by one.

Images