Preparation method for infrared polarization device and infrared polarization device

Abstract

The present disclosure relates to a preparation method for an infrared polarization device, and an infrared polarization device. The preparation method comprises: providing a substrate; forming a first electrode on one side of the substrate; forming, on the side of the first electrode away from the substrate, a first quantum dot detection structure having a preset relief pattern, wherein the first quantum dot detection structure is physically formed; and performing deposition on the side of the first quantum dot detection structure away from the first electrode so as to form a grating array structure, wherein the grating array structure is also used as a second electrode. In this way, forming a grating array structure by means of performing deposition on a first quantum dot detection structure having a preset relief pattern does not damage the chemical properties of the first quantum dot detection structure, thereby facilitating an improvement in the polarization detection performance of an infrared polarization device.

Description

Fabrication methods and infrared polarization devices

[0001] Cross-reference to related applications

[0002] This disclosure claims priority to Chinese Patent Application No. 202411199718.8, filed on August 29, 2024, entitled "Preparation Method of Infrared Polarizing Device and Infrared Polarizing Device", the entire contents of which are incorporated herein by reference. Technical Field

[0003] This disclosure relates to the field of infrared detection technology, and in particular to a method for preparing an infrared polarization device and the infrared polarization device itself. Background Technology

[0004] Currently, infrared imaging technology has attracted much attention due to its superior performance, such as long detection range, high detection sensitivity, and ability to operate at night. It is often used in combination with other technologies to expand its applications. For example, since different objects or even the same object will produce different polarization states, by combining polarization technology with infrared imaging technology, it is possible to easily identify target objects in complex backgrounds.

[0005] 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 technologies typically use photolithography to fabricate polarizers on the surface of colloidal quantum dots. This method of applying polarizers to the surface of colloidal quantum dots inevitably damages the chemical properties of the quantum dots, thereby leading to a decrease in the polarization detection performance of the infrared polarization device. Summary of the Invention

[0006] In order to solve the above-mentioned technical problems, or at least partially solve the above-mentioned technical problems, this disclosure provides a method for preparing an infrared polarization device and an infrared polarization device.

[0007] This disclosure provides a method for fabricating an infrared polarization device, comprising: providing a substrate, wherein a first electrode is formed 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 opposite to the substrate, wherein the first quantum dot detection structure is physically formed; depositing a grating array structure on the side of the first quantum dot detection structure opposite to the first electrode; wherein the grating array structure is reused as a second electrode.

[0008] In some embodiments, the method further includes: sequentially forming an N-type doped layer, an intrinsic quantum dot layer, and a P-type doped layer on the side of the grating array structure opposite to the first quantum dot detection structure to obtain a second quantum dot detection structure; and depositing a third electrode on the side of the second quantum dot detection structure opposite to the grating array structure.

[0009] In some embodiments, forming a first quantum dot detection structure with a predetermined uneven pattern on the side of the first electrode opposite to the substrate includes:

[0010] An N-type doped layer and an intrinsic quantum dot layer are sequentially formed on the side of the first electrode away from the substrate using spin coating or spray coating processes; the intrinsic quantum dot layer is imprinted using a nanoimprinting process to form the intrinsic quantum dot layer with a preset concave-convex pattern; a P-type doped layer is formed on the side of the intrinsic quantum dot layer away from the N-type doped layer using spin coating or spray coating processes.

[0011] This disclosure also provides an infrared polarization device, comprising: a substrate; a first electrode disposed on one side of the substrate; a first quantum dot detection structure disposed on the side of the first electrode opposite to the substrate; the first quantum dot detection structure having a preset concave-convex pattern and being physically formed; and a grating array structure disposed on the side of the first quantum dot detection structure opposite to the first electrode; wherein the grating array structure is reused as a second electrode.

[0012] In some embodiments, the infrared polarization device further includes: a second quantum dot detection structure disposed on the side of the grating array structure opposite to the first quantum dot detection structure; and a third electrode disposed on the side of the second quantum dot detection structure opposite to the grating array structure.

[0013] In some embodiments, both the second quantum dot detection structure and the first quantum dot detection structure include: an N-type doped layer, an intrinsic quantum dot layer, and a P-type doped layer sequentially stacked along the direction from the first electrode to the third electrode.

[0014] In some embodiments, the thickness of the N-type doped layer is 10 nm to 50 nm; the thickness of the intrinsic quantum dot layer is 400 nm to 500 nm; and the thickness of the P-type doped layer is 10 nm to 50 nm.

[0015] In some embodiments, the grating array structure includes grating units arranged in an array, and each grating unit includes grating lines alternately arranged at a first height and a second height along a direction perpendicular to the plane of the substrate; adjacent preset number of grating units form a grating group; the grating lines of each grating unit in the same grating group extend in different directions; the grating units with different grating line extension directions are used to transmit infrared light with different polarization directions.

[0016] In some embodiments, the grating lines of each grating unit in the same grating group extend at the same angle.

[0017] In some embodiments, the substrate includes a signal readout circuit; the signal readout circuit includes an array of pixel regions; and the vertical projection of the grating unit on the substrate corresponds one-to-one with the pixel regions.

[0018] The technical solution provided in this disclosure has the following advantages compared with the prior art:

[0019] The method for fabricating an infrared polarization device provided in this disclosure deposits a grating array structure on a first quantum dot detection structure with a preset concave-convex pattern, which does not damage the chemical properties of the first quantum dot detection structure, thereby improving the polarization detection performance of the infrared polarization device. Attached Figure Description

[0020] The accompanying drawings, which are incorporated in and form a part of this specification, illustrate embodiments consistent with this disclosure and, together with the description, serve to explain the principles of this disclosure.

[0021] To more clearly illustrate the technical solutions in the embodiments of this disclosure or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, those skilled in the art can obtain other drawings based on these drawings without creative effort.

[0022] Figure 1 is a schematic flowchart of a method for fabricating an infrared polarization device according to an embodiment of this disclosure;

[0023] Figure 2 is a schematic flowchart of an intrinsic quantum dot layer imprinting process provided in an embodiment of this disclosure;

[0024] Figure 3 is a schematic diagram of the structure of an infrared polarization device provided in an embodiment of this disclosure;

[0025] Figure 4 is a schematic diagram of another infrared polarization device provided in an embodiment of this disclosure;

[0026] Figure 5 is a schematic diagram of another infrared polarization device provided in an embodiment of this disclosure;

[0027] Figure 6 is a schematic diagram of another infrared polarization device provided in an embodiment of this disclosure;

[0028] Figure 7 is a schematic diagram of a grating array structure provided in an embodiment of this disclosure;

[0029] Figure 8 is a schematic diagram of the arrangement structure of a grating unit provided in an embodiment of this disclosure.

[0030] Among them, 01 is an N-type doped layer; 02 is an intrinsic quantum dot layer; 03 is a P-type doped layer; 210 is a substrate; 220 is a first electrode; 230 is a first quantum dot detection structure; 240 is a grating array structure; 241 is a grating unit; 2411 is a grating line; 250 is a second quantum dot detection structure; and 260 is a third electrode. Detailed Implementation

[0031] To better understand the above-mentioned objectives, features, and advantages of this disclosure, the solutions disclosed herein will be further described below. It should be noted that, unless otherwise specified, the embodiments and features described herein can be combined with each other.

[0032] Numerous specific details are set forth in the following description in order to provide a full understanding of this disclosure, but this disclosure may also be implemented in other ways different from those described herein; obviously, the embodiments in the specification are only some, and not all, of the embodiments of this disclosure.

[0033] In the field of infrared detection technology, infrared imaging technology has expanded the range of objective information that humans can observe, surpassing the limitations of visible light imaging, and has been widely used in military, security, fire protection, aerospace, and medical fields. However, traditional infrared detectors are constrained by complex molecular beam epitaxy and flip-chip bonding processes, resulting in high manufacturing costs. To overcome these bottlenecks, researchers have conducted relevant studies on materials for preparation. Among them, colloidal quantum dots have become an ideal choice for infrared applications due to their unique properties, such as tunable size-dependent optical characteristics and ease of processing.

[0034] With the continuous development of infrared imaging technology, it is often combined with other technologies to expand its applications. For example, polarization technology is a crucial property of light waves, completely independent of amplitude, phase, and frequency. When light interacts with an object, the object's inherent properties, such as surface roughness, shape, and material, impart a specific polarization state to the light wave. Utilizing this characteristic, in complex environments such as backgrounds similar to the target, polarization technology can detect the characteristic polarization signal of the object and reveal hidden targets through imaging.

[0035] In infrared polarization imaging systems, polarizers play a crucial role, becoming an indispensable component by identifying the polarization information of the object being measured. With the miniaturization, micro-miniaturization, and even integration of infrared polarization imaging systems becoming the main development trend, traditional infrared polarizers are no longer suitable. Therefore, how to fabricate smaller polarizers has become a key research focus.

[0036] In recent years, researchers have successfully fabricated small-sized polarizers, or nanograting structures, using various micro- and nanofabrication techniques. These structures, as novel devices with small size and high adaptability, have shown promising potential as alternatives. However, these nanograting structures are mainly fabricated on one side of colloidal quantum dots using photolithography. Since this method typically involves photochemical reactions, applying them to the surface of colloidal quantum dots inevitably damages the chemical properties of the quantum dots, leading to a decrease in the polarization detection performance of infrared polarization devices.

[0037] To address at least one of the aforementioned problems, this disclosure provides a method for fabricating an infrared polarization device. By depositing a grating array structure on a first quantum dot detection structure with a preset concave-convex pattern, the damage to the chemical properties of the quantum dots caused by the photolithography process is avoided, ensuring the stability of the chemical properties of the first quantum dot detection structure and improving the polarization detection performance of the infrared polarization device.

[0038] The following description, in conjunction with the accompanying drawings, illustrates the fabrication method of the infrared polarization device and the infrared polarization device provided in the embodiments of this disclosure.

[0039] Figure 1 is a schematic flowchart of a method for fabricating an infrared polarization device according to an embodiment of this disclosure. Referring to Figure 1, the method includes:

[0040] S110 provides a substrate.

[0041] A first electrode is formed on one side of the substrate.

[0042] For example, the substrate can be cleaned sequentially using acetone, isopropanol, and deionized water to achieve substrate cleaning. Additionally, the first electrode can be one or more of indium tin oxide (ITO), indium zinc oxide (IZO), and indium oxide (In2O3), with a thickness of 20 nm to 100 nm, and can be fabricated using physical vapor deposition (PVD) methods such as magnetron sputtering or thermal evaporation, or chemical vapor deposition (CVD). In some embodiments, the first electrode can also be other electrode materials, thicknesses, and electrode formation methods known to those skilled in the art, and are not limited herein.

[0043] S120. A first quantum dot detection structure with a preset concave-convex pattern is formed on the side of the first electrode away from the substrate.

[0044] In some embodiments, the first quantum dot detection structure is physically formed. Specifically, compared to the adverse effects on quantum dots caused by photolithography forming a preset concave-convex pattern, the first quantum dot detection structure of this disclosure is prepared by using physical forming technology to obtain a preset concave-convex pattern, which will not have an adverse effect on the quantum dot, such as damaging its chemical properties, and can be applied to a variety of material systems, showing good application prospects.

[0045] In some embodiments, the first quantum dot detection structure includes spaced-apart protrusions with a recess between adjacent protrusions, thereby forming a raised-lower pattern. It should be noted that the protrusions are strip-shaped, and the extension direction of the protrusions can be set according to the fabrication requirements of the infrared polarization device. For example, relative to a certain reference direction, the extension direction of the protrusions can be 0°, 22.5°, 45°, or other angles, which are not limited here.

[0046] S130, a grating array structure is deposited on the side of the first quantum dot detector structure away from the first electrode.

[0047] In some embodiments, the grating array structure is reused as a second electrode. Specifically, physical vapor deposition, chemical vapor deposition, or other deposition processes can be used to vertically deposit corresponding grating lines at the protruding and recessed structures of the first quantum dot detection structure to obtain the grating array structure. Compared with the prior art, which uses photolithography to prepare the grating array structure on one side of the quantum dot, the embodiments of this disclosure avoid the adverse effects of photochemical reactions in the photolithography process on the quantum dot, ensuring the stability of the chemical properties of the first quantum dot detection structure. Moreover, the preparation process is simple, and the grating lines formed there are no connections, which can reduce unnecessary material consumption and help reduce preparation costs.

[0048] In addition, the materials used to fabricate grating array structures include, but are not limited to, conductive materials such as metals. Taking metal materials as an example, grating array structures can be fabricated from metal materials such as aluminum, gold, silver, and chromium. The specific type of metal material can be selected according to the polarization performance requirements of the infrared polarization device, and is not limited here.

[0049] The method for fabricating an infrared polarization device provided in this disclosure includes: providing a substrate; forming a first electrode on one side of the substrate; forming a first quantum dot detection structure with a predetermined concave-convex pattern on the side of the first electrode opposite to the substrate; the first quantum dot detection structure being physically formed; and depositing a grating array structure on the side of the first quantum dot detection structure opposite to the first electrode; wherein the grating array structure is reused as a second electrode. Thus, by depositing a grating array structure on the first quantum dot detection structure with the predetermined concave-convex pattern, the chemical properties of the first quantum dot detection structure are not damaged, which is beneficial for improving the polarization detection performance of the infrared polarization device.

[0050] In some embodiments, based on Figure 1, the preparation method further includes the following steps:

[0051] Step 1: On the side of the grating array structure away from the first quantum dot detection structure, an N-type doped layer, an intrinsic quantum dot layer, and a P-type doped layer are formed sequentially to obtain the second quantum dot detection structure.

[0052] Specifically, the N-type doped layer, the intrinsic quantum dot layer, and the P-type doped layer can be stacked sequentially, for example, by spin coating or spray coating processes. In some embodiments, the second quantum dot detector structure can also be prepared using other methods known to those skilled in the art, which are not limited herein.

[0053] For example, the intrinsic quantum dot layer can be prepared from mercuric sulfide (HgS2), mercuric selenide (HgSe), indium antimonide (InSb), lead selenide (PbSe), or mercuric telluride (HgTe). The N-type doped layer can be prepared from ZnO (zinc oxide), bismuth sulfide (Bi2S3), or one of the same N-type quantum dots as the intrinsic quantum dots. The P-type doped layer can be prepared from molybdenum trioxide (MoO3), silver telluride (Ag2Te), or one of the same P-type quantum dots as the intrinsic quantum dots.

[0054] In some embodiments, an electron transport layer may be provided between the grating array structure and the N-type doped layer. The electron transport layer may be made of zinc oxide (ZnO), titanium dioxide (TiO2), or methyl butyrate (PCBM). A hole transport layer may also be formed above the P-type doped layer. The hole transport layer may be made of polystyrene sulfonate (PEDOT:PSS), molybdenum oxide (MoOx), or butylphenyl-N,N″-bisphenyl (PolyTPD). None of these are limited in their application.

[0055] Step 2: Deposit a third electrode on the side of the second quantum dot detector structure that is away from the grating array structure.

[0056] For example, the third electrode may be made of gold, aluminum, silver, or nickel, and its thickness may be 20 nm to 100 nm, and it may be prepared by magnetron sputtering, thermal evaporation, or electron beam evaporation. In some embodiments, the third electrode may also be other electrode materials, thicknesses, and electrode formation methods known to those skilled in the art, and are not limited herein.

[0057] In some embodiments, based on FIG1, S120 includes the following steps:

[0058] Step 1: Using spin coating or spray coating, an N-type doped layer and an intrinsic quantum dot layer are sequentially formed on the side of the first electrode away from the substrate.

[0059] Specifically, by sequentially forming the above films using spin coating or spray coating processes, the thickness of the corresponding films can be precisely controlled, thereby ensuring good thickness uniformity of the N-type doped layer and the intrinsic quantum dot layer, and guaranteeing the quality of film formation. Furthermore, the materials used to prepare the N-type doped layer and the intrinsic quantum dot layer in the first and second quantum dot detection structures can be the same, and will not be elaborated further here.

[0060] Step 2: The intrinsic quantum dot layer is imprinted using a nanoimprinting process to form an intrinsic quantum dot layer with a preset concave-convex pattern.

[0061] For example, Figure 2 is a schematic flowchart of an imprinting process for an intrinsic quantum dot layer provided in an embodiment of this disclosure. Referring to Figure 2, a nanoimprinting mold with a preset embossed pattern can be prepared first; then, the prepared nanoimprinting mold is brought into contact with the intrinsic quantum dot layer and a preset pressure is applied, such as 20 MPa to 70 MPa, thereby imprinting the preset embossed pattern on the surface of the intrinsic quantum dot layer onto the nanoimprinting mold (S134) and achieving precise transfer of the preset embossed pattern. In some embodiments, the magnitude of the preset pressure can be set according to the fabrication requirements of the infrared polarization device, which is not limited here.

[0062] For example, the fabrication process of a nanoimprint mold may include: S131: applying photoresist to the surface of a substrate using a spin coating process, and then placing the substrate coated with photoresist on a hot plate for a certain period of time to bake it to remove solvent components such as water in the photoresist, improve the contact strength between the substrate and the photoresist, and prepare for the fabrication of raised and recessed patterns on it; S132: then irradiating the photoresist with ultraviolet light, and exposing the photoresist surface by focusing the ultraviolet light through a mask to form an initial raised and recessed pattern; S133: developing and etching the exposed photoresist to form the desired raised and recessed pattern on the substrate.

[0063] Step 3: A P-type doped layer is formed on the side of the intrinsic quantum dot layer away from the N-type doped layer using spin coating or spray coating processes.

[0064] It should be noted that, since 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 sequentially formed above the first electrode, and a pre-defined embossing process is performed on the P-type doped layer to form a pre-defined convex-concave pattern, the P-type doped layer may be damaged in some areas, thus compromising its film integrity. However, in the embodiments of this disclosure, after forming a pre-defined convex-concave pattern on the surface of the intrinsic quantum dot layer, the P-type doped layer is formed from above it using a spin-coating or spray-coating process, thereby ensuring the uniformity and integrity of the P-type doped layer, which is beneficial for the infrared polarization device to achieve good detection performance.

[0065] For example, continuing to refer to Figure 2, after forming the P-type doped layer, metal can be deposited on top of the P-type doped layer (S135) to obtain a grating array structure, which significantly reduces the difficulty and cost of fabricating the grating array structure.

[0066] The nanoimprinting process provided in this embodiment adopts a mold replication method, which can quickly and massively produce structures with nanoscale features, such as first quantum dot detection structures, further improving the production efficiency of grating array structures. Moreover, the nanoimprinting mold can be reused, which greatly reduces the cost of the nanoimprinting process and is suitable for large-scale production.

[0067] Based on the above embodiments, this disclosure also provides an infrared polarization device, which is prepared by any of the infrared polarization device preparation methods provided in the above embodiments.

[0068] In some embodiments, FIG3 is a schematic diagram of an infrared polarization device provided in an embodiment of the present disclosure. Referring to FIG3, the infrared polarization device includes: a substrate 210; a first electrode 220 disposed on one side of the substrate 210; a first quantum dot detection structure 230 disposed on the side of the first electrode 220 opposite to 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 disposed on the side of the first quantum dot detection structure 230 opposite to the first electrode 220; wherein, the grating array structure 240 is reused as a second electrode.

[0069] The substrate 210 is used to support structures such as the first electrode 220, the first quantum dot detection structure 230, and the grating array structure 240. Exemplarily, the substrate 210 may be a silicon-based readout circuit substrate or other types of substrates used for detection and imaging, and is not limited herein.

[0070] The grating array structure 240 is used to transmit infrared light with different polarization directions. The polarization direction depends on the extension direction of the grating lines in the grating array structure 240; that is, different extension directions of the grating lines result in different polarization directions of the transmitted infrared light. Therefore, the extension directions of the grating lines in the grating array structure 240 can include multiple directions to transmit infrared light with different polarization directions, thereby improving imaging efficiency. The relationship between the extension direction of the grating lines and the polarization direction of the transmitted infrared light will be illustrated exemplarily below.

[0071] The first quantum dot detection structure 230 is used to perform photoelectric response on polarized infrared light. Specifically, the first quantum dot detection structure 230 absorbs infrared light with different polarization directions emitted from the grating array structure 240 and performs photoelectric response based on this infrared light; that is, the first quantum dot detection structure 230 converts infrared light signals with different polarization directions into corresponding electrical signals, so that subsequent related circuits can perform infrared polarization imaging using these electrical signals. The specific principle of infrared polarization imaging will be explained by example later.

[0072] By reusing the grating array structure 240 as the second electrode, the number of films in the infrared polarization device can be reduced, thereby reducing the overall size of the infrared polarization device, simplifying the film preparation process of the infrared polarization device, thus realizing the miniaturization design of the infrared polarization device, improving the preparation efficiency, and saving the overall application cost.

[0073] Compared to existing polarized infrared imaging technologies, where a single infrared polarization device can only acquire infrared images with different polarization directions in a time-division manner, making it impossible for existing infrared polarization devices to detect dynamic scenes in real time and accurately, or integrating multiple infrared polarization devices to acquire infrared images with multiple polarization directions results in an excessively large overall size, the infrared polarization device provided in this disclosure, through a grating array structure 240 transmitting infrared light with different polarization directions, can simultaneously acquire multiple infrared images with different polarization directions. This increases the polarization characteristics of the infrared images, reduces image interference, and thus improves the real-time performance and accuracy of infrared image acquisition, facilitating real-time and accurate detection of dynamic scenes. At the same time, it achieves a miniaturized design of the infrared polarization device.

[0074] In some embodiments, FIG4 is a schematic diagram of another infrared polarization device provided in this disclosure. Based on FIG3 and referring to FIG4, the infrared polarization device further includes: a second quantum dot detection structure 250 disposed on the side of the grating array structure 240 opposite to the first quantum dot detection structure 230; and a third electrode 260 disposed on the side of the second quantum dot detection structure 250 opposite to the grating array structure 240.

[0075] The second quantum dot detection structure 250 is used to perform photoelectric response on unpolarized infrared light, which contains all polarization information. Furthermore, the second quantum dot detection structure 250 has a preset transmittance for unpolarized infrared light, allowing a certain proportion of unpolarized infrared light to pass through. For example, the transmittance for unpolarized infrared light can be 60%, with the remaining 40% being absorbed by the second quantum dot detection structure 250. In some embodiments, the transmittance of the second quantum dot detection structure 250 for unpolarized infrared light can also be 50%, 70%, or other values. The transmittance 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; it is not limited here.

[0076] Specifically, in practical applications, a portion of the unpolarized infrared light is absorbed by the second quantum dot detection structure 250, and an electrical signal for the unpolarized infrared light is generated based on the photoelectric response. Correspondingly, another portion of the unpolarized infrared light is selectively transmitted by the grating array structure 240; that is, grating lines with different extension directions transmit infrared light with different polarization directions. The second quantum dot detection structure 250 then absorbs the infrared light with different polarization directions and generates an electrical signal for the polarized infrared light based on the photoelectric response. This simultaneous acquisition of polarization and unpolarization information allows for the acquisition of more comprehensive information about the observed object, improving imaging quality.

[0077] In some embodiments, the vertical projections of the first quantum dot detection structure and the second quantum dot detection structure coincide along a direction perpendicular to the plane of the substrate.

[0078] In this way, by setting the vertical projections of the first quantum dot detection structure and the second quantum dot detection structure to coincide, 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, which greatly improves the accuracy of target recognition.

[0079] In some embodiments, FIG5 is a schematic diagram of another infrared polarization device provided in this disclosure. Referring to FIG5, both the second quantum dot detection structure 250 and the first quantum dot detection structure 230 include: an N-type doped layer 01, an intrinsic quantum dot layer 02, and a P-type doped layer 03 sequentially stacked along the direction from the first electrode 220 to the third electrode 260.

[0080] It is easy 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, through the sequentially stacked N-type doped layer 01, intrinsic quantum dot layer 02, and P-type doped layer 03, constitute a photovoltaic infrared polarization device. In some embodiments, the second quantum dot detection structure 250 and the first quantum dot detection structure 230 may include only the intrinsic quantum dot layer 02 to constitute a photoconductive infrared polarization device.

[0081] The first electrode 220 is the bottom electrode of the infrared polarization device, 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, 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, used to collect holes generated by the photoelectric response of the second quantum dot detection structure 250.

[0082] Specifically, external infrared light, such as anisotropic infrared light emitted by the object under observation and ambient light, is transmitted through the top electrode. The second quantum dot detection structure 250 then performs a photoelectric response on a portion of the unpolarized infrared light, generating photogenerated carriers, i.e., electron-hole pairs. Because the intrinsic quantum dot is doped with N-type and P-type quantum dots, the electrons and holes generated in the second quantum dot detection structure 250 diffuse unevenly, thus forming a built-in potential. Under the action of the built-in potential, the electrons and holes dissociate into free electrons and holes, which then move to the top electrode and the middle electrode, respectively. Similarly, after another portion of the unpolarized infrared light is selectively transmitted through the grating array structure 240, the first quantum dot detection structure 230 performs a photoelectric response on infrared light with different polarization directions, generating holes and electrons that move to the middle electrode and the bottom electrode, respectively.

[0083] It should be noted that the photovoltaic infrared polarization device formed in the embodiments of this disclosure can operate normally under a low bias voltage (built-in potential) without the need for additional voltage application, and has good instantaneous response capability.

[0084] Compared to photoconductive infrared polarization devices, photogenerated carriers in photovoltaic infrared polarization devices can be directly separated under the influence of a built-in potential, reducing the diffusion and recombination of photogenerated carriers and resulting in a good photoelectric response. This, in turn, improves the signal-to-noise ratio of related signals such as electrical signals, which is beneficial for infrared polarization devices to perform high-sensitivity infrared detection.

[0085] In addition, embodiments of this disclosure can also apply voltage to the infrared polarization device through an external power source to enhance the built-in potential formed by the second quantum dot detection structure 250 and the first quantum dot detection structure 230, thereby increasing the movement speed of electrons and holes and driving electrons to move to the substrate 210 to form a directional current, so as to collect and process the electrical signal in the current.

[0086] In some embodiments, referring to FIG5, the thickness of the N-type doped layer 01 is 10 nm to 50 nm; the thickness of the intrinsic quantum dot layer 02 is 400 nm to 500 nm; and the thickness of the P-type doped layer 03 is 10 nm to 50 nm.

[0087] Thus, by setting the thicknesses of the N-type doped layer 01, the intrinsic quantum dot layer 02, and the P-type doped layer 03 to the above ranges, electrons and holes can move rapidly in their corresponding directions, ensuring efficient electron and hole transport. This results in a stronger photoelectric response of the infrared polarization device, facilitating better detection performance. The specific values ​​for the thicknesses 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 electron and hole transport requirements, and are not limited here.

[0088] In some embodiments, FIG6 is a schematic diagram of another infrared polarization device provided in the present disclosure, and FIG7 is a schematic diagram of a grating array structure provided in the present disclosure. Referring to FIG6 and FIG7, the grating array structure 240 includes grating units 241 arranged in an array, and along the direction perpendicular to the plane of the substrate 210, each grating unit 241 includes grating lines 2411 alternately arranged at a first height and a second height; an adjacent preset number of 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.

[0089] In the grating array structure 240, the grating groups are arranged in an array, and the array arrangement of each grating unit 241 in each grating group may be the same or different. For example, the grating units 241 in a grating group can be arranged in an n-row n-column manner, such as 3 rows and 3 columns, 4 rows and 4 columns, etc., or in a row and n columns, such as 1 row and 3 columns, 1 row and 5 columns, etc., or in an n-row m-column manner, where n and m are positive integers of different sizes, such as 2 rows and 3 columns, 3 rows and 4 columns, etc. In other embodiments, they can also be arranged in other ways known to those skilled in the art, which are not limited here.

[0090] In each grating unit 241, the grating lines 2411, alternately arranged at a first height and a second height, are not connected and are parallel to each other. For example, taking the orientation and structure shown in FIG6 as an example, if the structure extends vertically upwards from the bottom edge of the first quantum dot detection structure 230, the first height can be H1, and the second height can be H2, with the first height being greater than the second height. In other embodiments, the first height can also be less than the second height, as long as the first height and the second height are different; this is not limited here.

[0091] It should be noted that, compared to the method of setting grating lines 2411 at intervals only at a single height, the present embodiment increases the effective area of ​​grating lines 2411 by alternately setting 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, thereby improving the polarization effect of grating array structure 240.

[0092] In this design, the extension direction of the grating lines in the grating unit 241 corresponds one-to-one with the polarization direction of the infrared light. For example, taking a certain reference direction as a reference, if the extension direction of the grating lines in 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 extension direction of the grating lines in 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 correspondence between the extension direction of the grating lines and the polarization direction of the infrared light will be detailed later.

[0093] In some embodiments, the grating lines of each grating unit in the same grating group extend at intervals of the same angle.

[0094] For example, Figure 8 is a schematic diagram of the arrangement structure of a grating unit provided in an embodiment of this disclosure. Referring to Figure 8, Figure 8 shows a grating group including four grating units 241, with the grating lines of each grating unit 241 extending in directions spaced 45° apart from each other. For example, taking the orientation in Figure 8 as an example, relative to a reference direction (such as the vertical direction Y), the grating lines of the four grating units 241 extend in directions of 0°, 45°, 90°, and 135°, respectively. This indicates 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 acquired simultaneously, improving imaging efficiency.

[0095] For example, the grating lines of each grating unit 241 in the same grating group can be spaced apart by 10°, 30° or other angles, as long as the spacing angle is the same, and there is no limitation here.

[0096] In this way, by setting the extension directions of the grating lines of each grating unit 241 in the same grating group to be spaced at the same angle, the extension directions of the grating lines of each grating unit 241 are evenly spaced, thereby enabling the acquisition of uniform polarization information through each grating unit 241 in the grating group, which is beneficial to improving the subsequent imaging quality and reflecting the true information of the object to be observed.

[0097] In some embodiments, the period of the grating unit is 0.6µm to 1.0µm, and the duty cycle is 0.4 to 0.6.

[0098] Wherein, 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 embodiments of this disclosure, the grating unit is a subwavelength grating, and its period and duty cycle both satisfy the subwavelength condition.

[0099] It should be noted that 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. TE polarized light excites electrons on the grating lines to generate current, causing the TE polarized light to be reflected by the grating unit. TM polarized light, on the other hand, cannot generate current because the grating lines are isolated by air gaps. In this case, TM polarized light can be transmitted through the grating unit.

[0100] It is known that the main parameters for measuring the polarization performance of a grating unit include transmittance and extinction ratio. Transmittance represents the percentage of TM polarized light that passes 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 easy to see that, theoretically, the higher the transmittance and extinction ratio, the better the polarization performance of the grating unit.

[0101] In some embodiments, the period and duty cycle are important parameters affecting the polarization performance of the grating unit, directly influencing its optical response. Specifically, a higher duty cycle results in a larger area occupied by the grating lines and smaller spacing between them, thus enhancing the interaction between the lines and improving the grating unit's response to infrared light. For example, increasing the transmittance of the grating lines to TM-polarized light and the scattering efficiency to TE-polarized light allows more infrared light to interact with the grating unit, further increasing energy conversion efficiency. A smaller period can generate a higher frequency response, enabling the grating unit to transmit and refract higher-frequency infrared light, forming a high-resolution infrared polarization device and improving the quality of infrared polarization imaging.

[0102] Therefore, by setting the period of the grating unit to 0.6µm to 1.0µm and the duty cycle to 0.4 to 0.6, the embodiments of this disclosure can ensure that the grating unit has good polarization performance, thereby improving the quality of infrared polarization imaging.

[0103] In some embodiments, the grating lines of the grating unit are made of aluminum.

[0104] Different types of metal materials have different effects on the transmittance and extinction ratio of the grating unit. By selecting aluminum as the material for fabricating the grating lines, the transmittance and extinction ratio of the grating lines can be made to be relatively high, thereby ensuring that the grating unit has good polarization performance.

[0105] In some embodiments, the substrate includes a signal readout circuit; the signal readout circuit includes an array of pixel regions; the vertical projection of the grating unit on the substrate corresponds one-to-one with the pixel regions.

[0106] The substrate is provided with an array of pixel electrodes, which 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 via the first electrode. The electrical signals are then converted into digital signals and read out by a signal readout circuit. Finally, the digital signals are output to external related circuits for detection and imaging.

[0107] For example, based on the arrangement of grating units, the vertical projection of each grating unit on the substrate is located within the corresponding pixel region, and the vertical projection area of ​​each grating unit on the substrate is equal. For example, the vertical projection area of ​​each grating unit on the substrate can be less than or equal to the area of ​​the corresponding pixel region. In this way, while improving the integration between each grating unit, crosstalk between the corresponding infrared light transmitted by each grating unit can be avoided, thereby improving the accuracy of the polarization information collected by the infrared polarization device.

[0108] For example, the infrared polarization device provided in this disclosure can be an optoelectronic imaging device integrated with a complementary metal-oxide-semiconductor (CMOS) image sensor. The actual size of each grating unit matches the pixel size of the CMOS image sensor, and each grating unit corresponds one-to-one with the pixel size of the intrinsic quantum dot layer, so as to collect and process the infrared light emitted from each grating unit in different regions, thereby improving the accuracy of infrared image acquisition.

[0109] In some embodiments, the infrared polarization device further includes a data acquisition module and a data analysis and imaging system.

[0110] 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 analysis and processing results to obtain a polarization imaging image of the object under observation in the target band. For example, the target band can be at least one of shortwave infrared, midwave infrared, and longwave infrared, and is not limited thereto.

[0111] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0112] The above description is merely a specific embodiment of this disclosure, enabling those skilled in the art to understand or implement it. Various modifications to these embodiments will be readily 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 this disclosure. Therefore, this disclosure is not to be limited to the embodiments described herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for fabricating an infrared polarization device, characterized in that, include: Provide a base; A first electrode is formed on one side of the substrate; A first quantum dot detection structure with a preset concave-convex pattern is formed on the side of the first electrode opposite to the substrate. The first quantum dot detection structure is physically formed. A grating array structure is deposited on the side of the first quantum dot detection structure opposite to the first electrode, wherein the grating array structure is reused as the second electrode.

2. The method for fabricating an infrared polarization device according to claim 1, characterized in that, Also includes: An N-type doped layer, an intrinsic quantum dot layer, and a P-type doped layer are sequentially formed on the side of the grating array structure opposite to the first quantum dot detection structure to obtain the second quantum dot detection structure. A third electrode is deposited on the side of the second quantum dot detector structure that is away from the grating array structure.

3. The method for fabricating an infrared polarization device according to claim 1, characterized in that, The first quantum dot detection structure having a predetermined concave-convex pattern formed on the side of the first electrode opposite to the substrate includes: An N-type doped layer and an intrinsic quantum dot layer are sequentially formed on the side of the first electrode away from the substrate using spin coating or spray coating processes; The intrinsic quantum dot layer is imprinted using a nanoimprinting process to form the intrinsic quantum dot layer with a preset concave-convex pattern; A P-type doped layer is formed on the side of the intrinsic quantum dot layer away from the N-type doped layer using spin coating or spray coating processes.

4. An infrared polarization device, characterized in that, include: Base; The first electrode is disposed on one side of the substrate; The first quantum dot detection structure is disposed on the 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 is disposed on the side of the first quantum dot detector structure opposite to the first electrode; The grating array structure is reused as a second electrode.

5. The infrared polarization device according to claim 4, characterized in that, Also includes: The second quantum dot detection structure is disposed on the side of the grating array structure opposite to the first quantum dot detection structure; The third electrode is disposed on the side of the second quantum dot detection structure opposite to the grating array structure.

6. The infrared polarization device according to claim 5, characterized in that, Both the second quantum dot detection structure and the first quantum dot detection structure include an N-type doped layer, an intrinsic quantum dot layer, and a P-type doped layer sequentially stacked along the direction from the first electrode to the third electrode.

7. The infrared polarization device according to claim 6, characterized in that, The thickness of the N-type doped layer is 10 nm to 50 nm. The thickness of the intrinsic quantum dot layer is 400 nm to 500 nm. The thickness of the P-type doped layer is 10 nm to 50 nm.

8. The infrared polarization device according to claim 4, characterized in that, The grating array structure includes grating units arranged in an array, and each grating unit includes grating lines alternately arranged at a first height and a second height along a direction perpendicular to the plane of the substrate; A predetermined number of adjacent grating units form a grating group; the grating lines of each grating unit in the same grating group extend in different directions; the grating units with different grating line extension directions are used to transmit infrared light with different polarization directions.

9. The infrared polarization device according to claim 8, characterized in that, The grating lines of each grating unit in the same grating group extend at the same angles.

10. The infrared polarization device according to claim 8, characterized in that, The substrate includes a signal readout circuit; the signal readout circuit includes an array of pixel regions; The vertical projection of the grating unit onto the substrate corresponds one-to-one with the pixel region.

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