Infrared device and manufacturing method

Abstract

The present disclosure relates to an infrared device and a manufacturing method. The infrared device comprises: a substrate; and a detection unit provided on one side of the substrate. The detection unit comprises a quantum dot detection structure and a grating array structure which are vertically coupled. The grating array structure comprises grating units arranged in an array, and a preset number of adjacent grating units form a grating group. Grating lines of grating units in a same grating group extend in different directions; grating units having different grating line extension directions are used for transmitting infrared light in different polarization directions; and the quantum dot detection structure is used for generating corresponding electrical signals in response to the infrared light in the different polarization directions. In this way, the grating units having the different grating line extension directions are used to transmit infrared light in the different polarization directions, so that infrared images in the plurality of different polarization directions can be collected in real time, polarization characteristics of the infrared images are increased, and image interference is reduced, thereby improving real-time performance and accuracy of infrared image collection, and facilitating real-time and accurate detection of a dynamic scene.

Description

Infrared device and preparation method

[0001] The present disclosure claims priority to the Chinese patent application No. 202410986495.3, filed on July 23, 2024, and entitled "Infrared device and preparation method", the entire content of which is incorporated herein by reference. TECHNICAL FIELD

[0002] The present disclosure relates to the field of infrared detection technology, and in particular to an infrared device and a preparation method. BACKGROUND

[0003] At present, infrared detection technology is attracting much attention due to its long detection distance, high detection sensitivity, and excellent performance of working at night, and is often combined with other technologies to expand its use. For example, different objects or the same object can produce different polarization states, and by combining polarization technology with infrared detection technology, it is possible to easily identify target objects in a complex background.

[0004] However, existing polarization infrared imaging technologies, such as time-sharing polarization imaging, amplitude-sharing polarization imaging, and aperture-sharing polarization imaging, are similar to spectral imaging, and usually need to collect multiple groups of images in time-sharing manner to describe the polarization state of the entire scene, and may mask the real polarization characteristics in the entire scene, and even produce image interference such as artifacts caused by platform or scene movement, resulting in that it cannot achieve real-time and accurate detection of dynamic scenes. SUMMARY

[0005] In order to solve the above technical problems or at least partially solve the above technical problems, the present disclosure provides an infrared device and a preparation method.

[0006] The present disclosure provides an infrared device, comprising: a substrate; and a detection unit arranged on one side of the substrate; the detection unit comprises a quantum dot detection structure and a grating array structure coupled vertically, the grating array structure comprises a plurality of grating units arranged in an array, and a preset 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 for transmitting infrared light with different polarization directions, and the quantum dot detection structure is used for generating corresponding electrical signals in response to infrared light with different polarization directions.

[0007] In some embodiments, the quantum dot detection structure comprises: a first electrode arranged on one side of the substrate; an infrared photosensitive layer arranged on a side of the first electrode away from the substrate; and a second electrode arranged on a side of the infrared photosensitive layer away from the first electrode; and the grating array structure is arranged between the second electrode and the infrared photosensitive layer.

[0008] In some embodiments, the quantum dot detection structure comprises: a first electrode disposed on one side of the substrate; an infrared photosensitive layer disposed on a side of the first electrode away from the substrate; and a second electrode disposed on a side of the infrared photosensitive layer away from the first electrode; the second electrode is multiplexed as the grating array structure; each of the grating units is electrically connected.

[0009] In some embodiments, the period of the grating unit is 0.6-1.0 um, and the duty cycle is 0.4-0.6.

[0010] In some embodiments, the grating lines of each of the grating units in the same grating group extend in directions that are sequentially spaced by the same angle.

[0011] In some embodiments, the grating group further comprises a hollow area; the hollow area is used to transmit non-polarized infrared light.

[0012] In some embodiments, the hollow area is located in the central region of the grating group.

[0013] In some embodiments, the grating lines of the grating unit comprise a metal material.

[0014] In some embodiments, the substrate comprises a signal readout circuit; the signal readout circuit comprises an array of pixel regions; the vertical projection of the grating unit on the substrate corresponds one-to-one to the pixel region.

[0015] The present disclosure also provides a method for preparing an infrared device, the method comprising: providing a substrate; and forming a detection unit on one side of the substrate; the detection unit comprises a vertically coupled quantum dot detection structure and a grating array structure, the grating array structure comprises an array of grating units, and a predetermined number of adjacent grating units form a grating group; the grating lines of each of the grating units 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, and the quantum dot detection structure is used to generate corresponding electrical signals in response to infrared light with different polarization directions.

[0016] Compared with the prior art, the technical scheme provided by the embodiments of the present disclosure has the following advantages: the infrared device provided by the embodiments of the present disclosure comprises a substrate and a detection unit arranged on one side of the substrate; the detection unit comprises a quantum dot detection structure and a grating array structure coupled vertically, the grating array structure comprises arrayed grating units, and a preset 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 for transmitting infrared light with different polarization directions, and the quantum dot detection structure is used for generating corresponding electrical signals in response to infrared light with different polarization directions. In this way, by using the grating units with different grating line extension directions to transmit infrared light with different polarization directions, multiple infrared images with different polarization directions can be collected in real time, the polarization characteristics of the infrared images are increased, the image interference is reduced, and thus the real-time performance and accuracy of the infrared image collection are improved, which is beneficial to real-time and accurate detection of dynamic scenes. BRIEF DESCRIPTION OF DRAWINGS

[0017] The accompanying drawings, which are incorporated into and form part of the specification, illustrate embodiments consistent with the present disclosure and, together with the specification, serve to explain the principles of the present disclosure.

[0018] In order to more clearly illustrate the technical schemes in the embodiments of the present disclosure or the prior art, the accompanying drawings needed to be used in the embodiments or the prior art description will be briefly introduced as follows. Obviously, other drawings can also be obtained by those skilled in the art without creative labor under the premise of these drawings.

[0019] FIG. 1 is a structural schematic diagram of an infrared device provided by an embodiment of the present disclosure;

[0020] FIG. 2 is a structural schematic diagram of another infrared device provided by an embodiment of the present disclosure;

[0021] FIG. 3 is a structural schematic diagram of another infrared device provided by an embodiment of the present disclosure;

[0022] FIG. 4 is a structural schematic diagram of another infrared device provided by an embodiment of the present disclosure;

[0023] FIG. 5 is a working principle structural schematic diagram of a photovoltaic type infrared device provided by an embodiment of the present disclosure;

[0024] FIG. 6 is a structural schematic diagram of another infrared device provided by an embodiment of the present disclosure;

[0025] FIG. 7 is a schematic diagram of an arrangement structure of a grating unit provided by an embodiment of the present disclosure;

[0026] FIG. 8 is a schematic diagram of another arrangement structure of a grating unit provided by an embodiment of the present disclosure;

[0027] Fig. 9 is a flowchart of a method for preparing an infrared device according to an embodiment of the present disclosure.

[0028] Wherein, 01, electron transport layer; 02, N-type doped layer; 03, intrinsic quantum dot layer; 04, P-type doped layer; 05, hole transport layer; 110, substrate; 120, detection unit; 121, quantum dot detection structure; 122, grating array structure; 1221, grating unit; 1211, first electrode; 1212, infrared photosensitive layer; 1213, second electrode; 41, external power supply; 42, data acquisition module; 43, data analysis and imaging system. DETAILED DESCRIPTION

[0029] In order to more clearly understand the above-mentioned purposes, features and advantages of the present disclosure, the solutions 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.

[0030] In the following description, many specific details are set forth in order to provide a thorough understanding of the present disclosure, but the present disclosure can also be implemented in other different ways from those described herein; obviously, the embodiments in the description are only some embodiments of the present disclosure, not all embodiments.

[0031] Firstly, in combination with the related background, the defects of the prior art and the improvement points of the present disclosure are described.

[0032] The traditional infrared detection technology has been limited by the preparation process, for example: in the traditional infrared detection technology, flip-chip bonding technology is usually used to interconnect the infrared device and the silicon-based readout integrated circuit (ROIC), which leads to the complication of the preparation process and the significant increase in cost. To break through these bottlenecks, monolithic integration of colloidal quantum dots and silicon-based readout integrated circuits has become a feasible solution, and with the development of nanometer semiconductor materials, colloidal quantum dots have been gradually applied to infrared devices, promoting the development of infrared detection technology.

[0033] At present, infrared detection technology is attracting attention due to its long detection distance, high detection sensitivity, and excellent performance in working at night, and is often combined with other technologies to expand its use. For example, inspired by light waves, it can be known that light waves are a kind of electromagnetic waves, whose electric field vector and magnetic field vector are usually described by parameters such as electric field intensity, magnetic field intensity, electric displacement intensity, and magnetic flux density. Among them, the polarization property of light is defined as the vibration direction of the electric field vector when propagating in space, and different objects or the same object will produce different polarization states. By combining polarization technology with infrared detection technology, it is possible to easily identify target objects in a complex background.

[0034] However, in the existing polarized infrared imaging technology, an infrared device can only collect an infrared image of a polarization direction at a certain moment, and then collect infrared images of other different polarization directions in time division. The real polarization characteristics in the whole scene are easily covered due to the time interval and the polarization direction of the time division collection, and even there is image interference caused by platform or scene motion, which leads to that the existing infrared device cannot realize real-time and accurate detection of dynamic scenes.

[0035] In addition, if multiple infrared devices are integrated to collect multiple infrared images of different polarization directions at a certain moment, the overall volume will be too large, and the hardware application cost will be increased, which is not conducive to the wide application of infrared devices.

[0036] To solve at least one of the above problems, the present disclosure provides an infrared device, which can collect multiple infrared images of different polarization directions in real time by using grating cells with different grating line extension directions to transmit infrared light of different polarization directions, increase the polarization characteristics of the infrared images, reduce image interference, and thus improve the real-time and accuracy of infrared image collection, which is conducive to real-time and accurate detection of dynamic scenes.

[0037] The infrared device and the preparation method provided by the embodiments of the present disclosure will be exemplarily described below in combination with the accompanying drawings.

[0038] FIG. 1 is a structural schematic diagram of an infrared device provided by an embodiment of the present disclosure. Referring to FIG. 1, the infrared device includes a substrate 110 and a detection unit 120 arranged on one side of the substrate 110. The detection unit 120 includes a quantum dot detection structure 121 and a grating array structure 122 coupled vertically, the grating array structure 122 includes grating cells 1221 arranged in an array, and a preset number of adjacent grating cells 1221 form a grating group. The grating line extension directions of the grating cells 1221 in the same grating group are different. The grating cells 1221 with different grating line extension directions are used to transmit infrared light of different polarization directions, and the quantum dot detection structure 121 is used to generate corresponding electrical signals in response to the infrared light of different polarization directions.

[0039] In some embodiments, the substrate 110 is a substrate for carrying the detection unit 120. Exemplarily, the substrate 110 can be a silicon-based readout circuit substrate or other types of substrates for detecting imaging, which is not limited herein.

[0040] In some embodiments, the quantum dot detection structure 121 and the grating array structure 122 are arranged in a direction perpendicular to the plane on which the substrate 110 is located on the same side of the substrate 110, so that the quantum dot detection structure 121 and the grating array structure 122 form a vertical coupling, which can reduce the area occupied by the two on the substrate 110 and improve the overall integration level. For example, the grating array structure 122 can be located above the entire quantum dot detection structure 121 or below the relevant structure in the quantum dot detection structure 121, as long as the grating array structure 122 and the quantum dot detection structure 121 can respectively realize the corresponding functions, which are not limited herein.

[0041] In some embodiments, the grating groups in the grating array structure 122 are arranged in an array, and the array arrangement of the grating units 1221 in each grating group is the same or different. For example, the grating units 1221 in a grating group can be arranged in the form of n rows and n columns, such as 3 rows and 3 columns, 4 rows and 4 columns, etc., or in the form of one row and n columns, such as 1 row and 3 columns, 1 row and 5 columns, etc., or in the form of n rows and m columns, n and m being different positive integers, such as 2 rows and 3 columns, 3 rows and 4 columns, etc., or in other ways known to those skilled in the art, which are not limited herein.

[0042] It can be understood that the array arrangement of the grating units 1221 in each grating group depends on the aspect ratio of the infrared device provided by the embodiments of the present disclosure. The embodiments of the present disclosure can set the arrangement of the grating units 1221 based on the aspect ratio of the infrared device to ensure that the grating units 1221 in each grating group can be maximally laid on the preset plane of the infrared device (such as the focal plane), i.e., the relevant plane on which the grating array structure 122 is located, thereby improving the space utilization and preventing the infrared device from generating too many blind elements and bad points, and improving the success rate of imaging detection of the infrared device.

[0043] In some embodiments, the grating unit 1221 includes grating lines arranged at intervals and parallel to each other, and the grating line extension direction of the grating unit 1221 has a one-to-one corresponding relationship with the polarization direction of the infrared light. For example, taking a reference direction as a reference, if the grating line extension direction of a certain grating unit 1221 is parallel to the reference direction, it can transmit infrared light with a polarization direction parallel to the reference direction; if the grating line extension direction of a certain grating unit 1221 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 grating line extension direction and the polarization direction of the infrared light is described in detail below.

[0044] Specifically, on a reference plane, such as the plane on which the grating array structure 122 is located, the grating lines of the grating units 1221 in the same grating group have different extension directions, that is, the grating lines of the grating units 1221 in the same grating group have different inclination angles with respect to the same reference direction. In this way, the grating units with different grating line extension directions can transmit infrared light with different polarization directions, enriching the polarization information of the infrared light, and thus ensuring the real-time and accuracy of infrared image acquisition.

[0045] In some embodiments, the quantum dot detection structure 121 is used at least to generate a photoelectric response. Specifically, the quantum dot detection structure 121 absorbs infrared light with different polarization directions emitted from the grating array structure 122 and performs a photoelectric response based on the infrared light, that is, converts infrared light signals with different polarization directions into corresponding electrical signals, so that subsequent related circuits perform infrared polarization imaging through the electrical signals. The specific principle of infrared polarization imaging is exemplarily described below.

[0046] The infrared device provided by the embodiments of the present disclosure includes a substrate 110 and a detection unit 120 arranged on one side of the substrate 110. The detection unit 120 includes a quantum dot detection structure 121 and a grating array structure 122 coupled vertically. The grating array structure 122 includes grating units 1221 arranged in an array, and a preset number of adjacent grating units 1221 form a grating group. The grating lines of the grating units 1221 in the same grating group have different extension directions. The grating units 1221 with different grating line extension directions are used to transmit infrared light with different polarization directions, and the quantum dot detection structure 121 is used to generate corresponding electrical signals in response to infrared light with different polarization directions. In this way, by using the grating units 1221 with different grating line extension directions to transmit infrared light with different polarization directions, multiple infrared images with different polarization directions can be acquired in real time, the polarization characteristics of the infrared images are increased, image interference is reduced, and thus the real-time and accuracy of infrared image acquisition are improved, which is beneficial to real-time and accurate detection of dynamic scenes.

[0047] In some embodiments, FIG. 2 is a structural schematic diagram of another infrared device provided by the embodiments of the present disclosure. Based on FIG. 1, referring to FIG. 2, the quantum dot detection structure 121 includes a first electrode 1211 arranged on one side of the substrate 110, an infrared photosensitive layer 1212 arranged on a side of the first electrode 1211 away from the substrate 110, and a second electrode 1213 arranged on a side of the infrared photosensitive layer 1212 away from the first electrode 1211. The grating array structure 122 is arranged between the second electrode 1213 and the infrared photosensitive layer 1212.

[0048] Exemplarily, taking the orientation and structure shown in FIG. 2 as an example, the first electrode 1211, the infrared photosensitive layer 1212, the grating array structure 122 and the second electrode 1213 are sequentially stacked above the substrate 110.

[0049] FIG. 3 is a structural schematic diagram of another infrared device provided by the embodiment of the present disclosure. Based on FIG. 2, referring to FIG. 3, the infrared photosensitive layer 1212 can include an electron transport layer 01, an N-type doped layer 02, an intrinsic quantum dot layer 03, a P-type doped layer 04 and a hole transport layer 05 which are sequentially stacked above the first electrode 1211. In this way, a photovoltaic type infrared device vertically coupled in the direction from the first electrode 1211 to the second electrode 1213 is formed.

[0050] FIG. 4 is a structural schematic diagram of another infrared device provided by the embodiment of the present disclosure. Based on FIG. 2, referring to FIG. 4, the infrared photosensitive layer 1212 can include an intrinsic quantum dot layer 03 above the first electrode 1211. In this way, a photoconductive type infrared device vertically coupled in the direction from the first electrode 1211 to the second electrode 1213 is formed.

[0051] In some embodiments, the first electrode 1211 is a bottom electrode of the quantum dot detection structure 121, used for collecting electrons generated by photoelectric response. Exemplarily, the first electrode 1211 can be one or more of indium tin oxide (ITO), zinc oxide (ZnO), indium oxide (In2O3) and carbon nanotube, and can be prepared by magnetron sputtering, thermal evaporation and the like. In other embodiments, it can also be other electrode materials and electrode forming methods known to those skilled in the art, which are not limited herein.

[0052] In some embodiments, the second electrode 1213 is a top electrode of the quantum dot detection structure 121, used for collecting holes generated by photoelectric response. Exemplarily, the second electrode 1213 can be a transparent electrode for facilitating the transmission of infrared light, such as one or more of indium tin oxide (ITO), zinc oxide (ZnO), indium oxide (In2O3) and carbon nanotube, and can be prepared by magnetron sputtering, electron beam evaporation and the like. In other embodiments, it can also be other electrode materials and electrode forming methods known to those skilled in the art, which are not limited herein.

[0053] In some embodiments, the infrared photosensitive layer 1212 is a film layer for photoelectric response. Specifically, external infrared light such as anisotropic infrared light emitted by an object to be observed and ambient light are transmitted through the top electrode, and then the grating cells 1221 with different grating line extension directions in the grating array structure 122 transmit infrared light with different polarization directions to the infrared photosensitive layer 1212. The infrared photosensitive layer 1212 can generate photoelectron-hole pairs, which are received by the corresponding electrodes such as the first electrode 1211 and the second electrode 1213 for imaging.

[0054] For example, for a photovoltaic infrared device, since the intrinsic quantum dots are doped by N-type quantum dots and P-type quantum dots, the generated electrons and holes in the infrared photosensitive layer 1212 are not uniformly diffused, so that an internal built-in potential can be formed in the photovoltaic infrared device. Under the action of the working voltage applied by the external power supply, the internal built-in potential is further enhanced. Then, the electron-hole pairs are dissociated into free electrons and holes under the action of the enhanced internal built-in potential. The holes are transmitted to the second electrode 1213 through the hole transport layer 05, and the electrons are transmitted to the first electrode 1211 through the electron transport layer 01. For a photoconductive infrared device, the photoelectron-hole pairs can be separated under the action of the working voltage applied by the external power supply, and the electrons and holes are directly transmitted to the first electrode 1211 and the second electrode 1213, respectively.

[0055] For example, FIG. 5 is a working principle structure schematic diagram of a photovoltaic infrared device provided by an embodiment of the present disclosure. Based on FIG. 2, referring to FIG. 5, on the basis that the grating array structure 122 is arranged between the second electrode 1213 and the infrared photosensitive layer 1212, the top electrode and the bottom electrode of the infrared device are connected to an external power supply 41. The external power supply 41 can further drive the electric signal (i.e., electrons) generated by photoelectric response to move to the substrate 110 by applying a working voltage to the infrared device, so as to form a directional moving current, so as to collect and process the electric signal in the current.

[0056] In some embodiments, FIG. 6 is a structure schematic diagram of another infrared device provided by an embodiment of the present disclosure. Based on FIG. 1, referring to FIG. 6, the quantum dot detection structure includes: the first electrode 1211 arranged on one side of the substrate 110; the infrared photosensitive layer 1212 arranged on the side of the first electrode 1211 away from the substrate 110; and the second electrode 1213 arranged on the side of the infrared photosensitive layer 1212 away from the first electrode 1211; wherein the second electrode 1213 is multiplexed as a grating array structure; and each grating cell 1221 is electrically connected.

[0057] Specifically, the second electrode 1213, multiplexed as a grating array structure, selectively transmits external infrared light, including: grating units with different grating line extension directions transmit infrared light with different polarization directions to the infrared photosensitive layer 1212; the infrared photosensitive layer 1212 generates photogenerated electron-hole pairs; subsequently, holes are transported to the second electrode 1213, and electrons are transported to the first electrode 1211. In some embodiments, when the second electrode 1213 is multiplexed as a grating array structure, the infrared device can be a photoconductive infrared device or a photovoltaic infrared device. The specific structure of the infrared photosensitive layer 1212 can be understood by referring to the corresponding embodiments above, and will not be repeated here.

[0058] Specifically, by reusing the second electrode 1213 as a grating array structure, the number of film layers in the entire infrared device can be reduced, thereby reducing the overall size of the infrared device and simplifying the film layer preparation process of the infrared device. This achieves miniaturization of the infrared device, improves preparation efficiency, and saves overall application costs.

[0059] It should be noted that each grating unit in the grating array structure is provided with a metal frame, and the grating units are connected to each other through the metal frame to form an electrical connection. With this setting, when the external power supply applies the working voltage to the second electrode 1213 which is multiplexed into a grating array structure, the working voltage of each grating unit can be kept consistent, which is beneficial to the normal operation of the infrared device.

[0060] In some embodiments, referring to FIG1, the period of the grating unit 1221 is 0.6um to 1.0um, and the duty cycle is 0.4 to 0.6.

[0061] 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 1221. In particular, in the embodiments of this disclosure, the grating unit 1221 is a subwavelength grating, and its period and duty cycle both satisfy the subwavelength condition.

[0062] Based on this, the design requirements of the grating unit 1221 will be explained below in conjunction with the polarization principle of the grating unit 1221.

[0063] It should be noted that when the period of the grating unit 1221 is less than the wavelength of the incident infrared light, it can exhibit polarization characteristics. Specifically, 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. Due to the different boundary conditions, their equivalent refractive indices are also different. This can be manifested as follows: TE polarized light will excite electrons on the grating lines to generate a current, causing the TE polarized light to be reflected by the grating unit 1221, while TM polarized light cannot generate a current because the grating lines are isolated by the air gap. In this case, TM polarized light can be transmitted through the grating unit 1221.

[0064] Combining the TM polarized light and TE polarized light mentioned above, the main parameters for evaluating the polarization performance of grating unit 1221 include transmittance and extinction ratio. Transmittance represents the percentage of TM polarized light that passes through grating unit 1221, and extinction ratio represents the ratio of the transmittance of TM polarized light to the transmittance of TE polarized light. Theoretically, the higher the transmittance and extinction ratio, the better the polarization performance of grating unit 1221.

[0065] The period and duty cycle are important parameters affecting the polarization performance of the grating unit 1221, directly influencing its optical response. Specifically, regarding the duty cycle, generally, a higher duty cycle of the grating unit 1221 results in a larger area occupied by the grating lines and a smaller spacing between them, thus enhancing the interaction between the grating lines. This strengthens the response of the grating unit 1221 to infrared light, such as increasing the transmittance of the grating lines to TM polarized light and increasing the scattering efficiency of the grating lines to TE polarized light. Furthermore, as more and more infrared light interacts with the grating unit 1221, the energy conversion efficiency is further increased. Regarding the period, a smaller period can produce a higher frequency response, enabling the grating unit 1221 to transmit and refract higher frequency infrared light, thereby forming a high-resolution infrared device and improving the quality of infrared polarization imaging.

[0066] Therefore, by setting the period of the grating unit 1221 to 0.6µm to 1.0µm and the duty cycle to 0.4 to 0.6, the present embodiment can ensure that the grating unit 1221 has good polarization performance and further improve the quality of infrared polarization imaging.

[0067] In some embodiments, the grating lines of each grating unit in the same grating group extend at intervals of the same angle.

[0068] For example, Figure 7 is a schematic diagram of the arrangement structure of a grating unit provided in an embodiment of the present disclosure. Based on Figure 1, referring to Figure 7, Figure 7 shows a grating group including four grating units 1221. The grating lines of each grating unit 1221 extend in directions spaced 45° apart from each other. For example, taking the orientation in Figure 7 as an example, relative to the reference direction (such as the vertical direction Y), the grating lines of the four grating units 1221 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.

[0069] Specifically, by setting the extension directions of the grating lines of each grating unit 1221 in the same grating group to be spaced at the same angle, the extension directions of the grating lines of each grating unit 1221 are spaced evenly, thereby enabling the acquisition of uniform polarization information through each grating unit 1221 in the grating group, which is beneficial to improving the subsequent imaging quality and reflecting the true information of the object to be observed.

[0070] In some embodiments, if the grating lines of each grating unit 1221 in the same grating group extend at different angles, uneven polarization information will be collected by each grating unit 1221 in the grating group. For example, polarization information at some angles will be collected more densely, while polarization information at other angles will be collected more sparsely, which will reduce the subsequent imaging quality.

[0071] For example, the grating lines of each grating unit 1221 in the same grating group can extend at intervals of 10°, 30° or other angles, as long as the interval angle is the same, which is not limited here.

[0072] In some embodiments, FIG8 is a schematic diagram of another arrangement structure of grating units provided in this disclosure. Based on FIG1 and referring to FIG8, the grating group further includes a cutout area 31; the cutout area 31 is used to transmit unpolarized infrared light.

[0073] Preferably, the cutout area 31 is located in the central region of the grating group. For example, Figure 8 shows a grating group including one cutout area 31 and eight grating units 1221. The eight grating units 1221 are arranged around the cutout area 31, and the grating lines of each grating unit 1221 extend at 22.5° intervals. For example, taking the orientation in Figure 8 as an example, relative to a reference direction (such as the vertical Y direction), the grating lines of the eight grating units 1221 extend at 0°, 22.5°, 45°, 67.5°, 90°, 112.5°, 135°, and [other angles not specified]. The value of 157.5° indicates that the grating assembly can simultaneously transmit infrared light with eight different polarization directions, corresponding to infrared light with polarization directions of 0°, 22.5°, 45°, 67.5°, 90°, 112.5°, 135°, and 157.5°, respectively. At the same time, the hollow area 31 can directly transmit non-polarized infrared light, which contains all polarization information. This enables the simultaneous acquisition of polarization and non-polarization information, thereby obtaining more comprehensive information about the object under observation and improving the accuracy of target recognition and classification.

[0074] Furthermore, by placing the cutout area 31 in the central region of the grating group, crosstalk of non-polarization information between grating groups can be avoided when the cutout area 31 is placed in the peripheral region of the grating group, which is beneficial for accurately identifying the object to be observed. In other embodiments, the cutout area 31 may also be placed in other positions in the central region of the grating group, which is not limited here.

[0075] In some embodiments, the grating lines of the grating unit comprise a metallic material.

[0076] For example, the metal material may include aluminum, gold, silver, chromium or other metal materials. The type of metal material may be selected according to the polarization performance requirements of the grating unit in the embodiments of this disclosure, and is not limited herein.

[0077] Different types of metallic materials have different effects on the transmittance and extinction ratio of grating units. For example, when the grating lines of the grating unit are made of aluminum, its corresponding transmittance and extinction ratio are both high, thereby ensuring that the grating unit has good polarization performance.

[0078] In some embodiments, referring to FIG1, the substrate 110 includes a signal readout circuit; the signal readout circuit includes an array of pixel regions; the vertical projection of the grating unit 1221 on the substrate 110 corresponds one-to-one with the pixel regions.

[0079] In some embodiments, the substrate 110 is provided with an array of pixel electrodes, which are electrically connected to the first electrode. Specifically, under the operating voltage applied by an external power supply, the electrical signal in the infrared photosensitive layer is transmitted through the first electrode to the pixel electrodes at different positions. The electrical signal is then converted into a digital signal and read out by a signal readout circuit, and then the digital signal is output to an external related circuit for detection and imaging.

[0080] For example, based on the array arrangement of grating units 1221, the vertical projection of each grating unit 1221 on the substrate 110 is located within the corresponding pixel region, and the vertical projection area of ​​each grating unit 1221 on the substrate 110 is equal. For example, the vertical projection area of ​​each grating unit 1221 on the substrate 110 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 1221, crosstalk between the corresponding infrared light transmitted by each grating unit 1221 can be avoided, thereby improving the accuracy of the polarization information collected by the infrared device.

[0081] It is understood that the infrared device provided in this disclosure is 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.

[0082] In some embodiments, referring to FIG5, the infrared device further includes a data acquisition module 42 and a data analysis and imaging system 43.

[0083] In some embodiments, the data acquisition module 42 is used to acquire the digital signal output by the signal readout circuit, and the data analysis and imaging system 43 is used to analyze the digital signal and perform infrared polarization imaging. Specifically, the data analysis and imaging system 43 can integrate the digital signal acquired by the data acquisition module 42, 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 to be observed in the target band. Exemplarily, the target band can be at least one of shortwave infrared, midwave infrared, and longwave infrared, and is not limited thereto.

[0084] In some embodiments, referring to Figure 1, in this infrared device, quantum dot detection structures can be arrayed above a substrate, with each quantum dot detection structure located within a corresponding pixel region. Furthermore, grating units are vertically coupled one-to-one with each quantum dot detection structure. This configuration ensures that infrared light emitted from the grating unit is received by the corresponding quantum dot detection structure. Compared to a single quantum dot detection structure receiving infrared light emitted from multiple grating units, this method effectively reduces crosstalk during infrared light reception, thereby improving the accuracy of infrared image acquisition.

[0085] For example, the arrayed quantum dot detector structure can be formed by photolithography or other fabrication methods known to those skilled in the art, and is not limited herein.

[0086] Based on the above embodiments, this disclosure also provides a method for preparing an infrared device, which can be used to prepare any of the infrared devices provided in the above embodiments.

[0087] In some embodiments, FIG9 is a schematic flowchart of a method for fabricating an infrared device according to an embodiment of the present disclosure. Referring to FIG9, the method includes the following steps.

[0088] S210 provides a base.

[0089] For example, the substrate can be cleaned by sequentially using acetone, isopropanol, and deionized water.

[0090] S220, A detection unit is formed on one side of the substrate.

[0091] In some embodiments, the detection unit includes a vertically coupled quantum dot detection structure and a grating array structure. The grating array structure includes grating units arranged in an array, and 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. Grating units with different grating line extension directions are used to transmit infrared light with different polarization directions, and the quantum dot detection structure is used to generate corresponding electrical signals in response to infrared light with different polarization directions. The specific fabrication steps of the detection unit will be detailed later and will not be repeated here.

[0092] In some embodiments, the step of forming a quantum dot detector structure includes the following steps.

[0093] Step 1: Form the first electrode on one side of the substrate.

[0094] For example, the first electrode can be prepared by magnetron sputtering or electron beam evaporation, and its thickness can be 30 nm to 60 nm. There are no limitations on the preparation method and thickness of the first electrode.

[0095] Step 2: Form an infrared photosensitive layer on the side of the first electrode away from the substrate.

[0096] For example, taking an infrared photosensitive layer comprising an electron transport layer, an N-type doped layer, an intrinsic quantum dot layer, a P-type doped layer, and a hole transport layer sequentially stacked on a first electrode as an example, the above film layers can be formed by spin coating, spraying, or other methods. In other embodiments, other methods known to those skilled in the art can also be used to prepare the infrared photosensitive layer, which are not limited here.

[0097] For example, the thickness of the electron transport layer can be 5nm to 20nm, the thickness of the N-type doped layer can be 50nm to 200nm, the thickness of the P-type doped layer can be 50nm to 200nm, and the thickness of the hole transport layer can be 5nm to 20nm, which are not limited here.

[0098] For example, the electron transport layer can be made of zinc oxide (ZnO), titanium dioxide (TiO2), or methyl butyrate (PCBM); the N-type doped layer can be made of ZnO (zinc oxide), bismuth sulfide (Bi2S3), or one of the N-type quantum dots that are the same as the intrinsic quantum dots; the intrinsic quantum dot layer can be made of mercuric sulfide (HgS2), mercuric selenide (HgSe), indium antimonide (InSb), or lead selenide (PbSe); the P-type doped layer can be made of molybdenum trioxide (MoO3), silver telluride (Ag2Te), or one of the P-type quantum dots that are the same as the intrinsic quantum dots; and the hole transport layer can be made of polystyrene sulfonate (PEDOT:PSS), molybdenum oxide (MoOx), or butylphenyl-N,N″-bisphenyl (PolyTPD), and none of these are limited here.

[0099] It should be noted that in the synthesis of intrinsic colloidal quantum dots, the embodiments of this disclosure can precisely control the absorption wavelength and particle size of intrinsic colloidal quantum dots by precisely controlling the reaction time and reaction temperature. For example, the longer the reaction time and the higher the reaction temperature, the longer the absorption wavelength and the larger the particle size of the intrinsic colloidal quantum dots. Here, there is no limitation on the absorption wavelength and particle size of intrinsic colloidal quantum dots, as long as the absorption wavelength can cover the short-wave infrared, mid-wave infrared and long-wave infrared range.

[0100] Step 3: Form a second electrode on the side of the infrared photosensitive layer opposite to the first electrode.

[0101] For example, the second electrode can be prepared by magnetron sputtering or electron beam evaporation, and its thickness can be 30 nm to 60 nm. There are no limitations on the preparation method and thickness of the second electrode.

[0102] In some embodiments, the grating array structure is disposed between the second electrode and the infrared photosensitive layer, and the specific fabrication steps of the grating array structure are described exemplarily below.

[0103] In some embodiments, forming a grating array structure specifically includes the following steps.

[0104] Step 1: Provide a photoresist coating layer of preset thickness.

[0105] Specifically, a photoresist of a predetermined thickness can be coated on the upper surface of the hole transport layer to form a photoresist coating layer for subsequent fabrication of the photoresist processing layer. For example, the thickness of the photoresist can be 40 nm, 60 nm, or other thicknesses known to those skilled in the art, and is not limited herein.

[0106] Step 2: The photoresist coating layer is pre-baked, exposed, and developed sequentially to form a photoresist treatment layer with a preset pattern.

[0107] In some embodiments, the photoresist coating is formed into a photoresist treatment layer by photolithography. For example, the photoresist coating can be irradiated with ultraviolet light, and the ultraviolet light can be focused on the surface of the photoresist coating using a mask to form a photoresist treatment layer with a preset pattern.

[0108] For example, the photoresist processing layer may include groove structures and protrusion structures to correspond to the pattern required to form the grating. The specific shape of the pattern may be set according to the grating fabrication requirements of the embodiments of this disclosure, and is not limited herein.

[0109] Step 3: Deposit a metal thin film onto the photoresist treatment layer using electron beam evaporation or sputtering to obtain the sample to be processed.

[0110] For example, the material of the metal film may be aluminum, copper, silver, chromium, nickel or other metal materials, which are not limited herein.

[0111] Step 4: Soak and peel the sample to be treated with an organic solution to obtain a metal grating or grating array structure.

[0112] For example, the organic solution may be acetone. In other embodiments, the organic solution may also be other types of organic solutions known to those skilled in the art, and is not limited herein.

[0113] 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.

[0114] 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. An infrared device, wherein, The infrared device comprises: a substrate; a detection unit arranged on one side of the substrate; the detection unit comprises a quantum dot detection structure and a grating array structure which are vertically coupled, the grating array structure comprises grating units arranged in an array, and a preset number of adjacent grating units form a grating group; 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 for transmitting infrared light with different polarization directions, and the quantum dot detection structure is used for generating corresponding electrical signals in response to infrared light with different polarization directions.

2. The infrared device according to claim 1, wherein the quantum dot detection structure comprises: a first electrode arranged on one side of the substrate; an infrared photosensitive layer arranged on a side of the first electrode away from the substrate; and a second electrode arranged on a side of the infrared photosensitive layer away from the first electrode; the grating array structure is arranged between the second electrode and the infrared photosensitive layer.

3. The infrared device according to claim 1, wherein the quantum dot detection structure comprises: a first electrode arranged on one side of the substrate; an infrared photosensitive layer arranged on a side of the first electrode away from the substrate; and a second electrode arranged on a side of the infrared photosensitive layer away from the first electrode; the second electrode is multiplexed as the grating array structure; and each grating unit is electrically connected.

4. The infrared device according to claim 1, wherein a period of the grating unit is 0.6-1.0 um, and a duty cycle is 0.4-0.

6.

5. The infrared device according to claim 1, wherein grating lines of each grating unit in the same grating group extend in directions which are equally spaced by the same angle.

6. The infrared device according to claim 1, wherein the grating group further comprises a hollow area; and the hollow area is used for transmitting unpolarized infrared light.

7. The infrared device according to claim 6, wherein the hollow area is located in a central region of the grating group.

8. The infrared device according to claim 1, wherein grating lines of the grating unit comprise a metal material.

9. The infrared device according to any one of claims 1-8, wherein the substrate comprises a signal readout circuit; the signal readout circuit comprises pixel regions arranged in an array; a vertical projection of the grating unit on the substrate corresponds to the pixel region one by one. The method comprises:

10. A method of fabricating an infrared device, wherein, providing a substrate; and forming a detection unit on one side of the substrate; the detection unit comprises a quantum dot detection structure and a grating array structure which are vertically coupled, the grating array structure comprises grating units arranged in an array, and a preset number of adjacent grating units form a grating group; 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 for transmitting infrared light with different polarization directions, and the quantum dot detection structure is used for generating corresponding electrical signals in response to infrared light with different polarization directions. ​

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