A mid-infrared detection array based on grating modulation photoelectric gain

Abstract

This invention discloses a mid-infrared detection array based on gate modulation photoelectric gain. The mid-infrared detection array is constructed on a flexible insulating substrate and includes a plurality of pixel units arranged in a periodic array. From bottom to top, each pixel unit includes: a gate, an insulating layer, a source, an active layer, and a drain. The active layer includes a lead selenide thin film, a two-dimensional molybdenum disulfide layer, and a black phosphorus quantum dot layer sequentially covering the source. Both the source and drain are interdigitated and symmetrically staggered in planar projection. The mid-infrared detection array of this invention can achieve flexible switching between fast response and high gain modes to meet the detection requirements of both high-frequency transient and low-frequency slowly varying signals, while improving the detection sensitivity of mid-infrared signals, reducing noise and dark current, and reducing the power consumption of the device.

Description

Technical Field

[0001] This invention belongs to the field of mid-infrared photoelectric detection, and particularly relates to a mid-infrared detection array based on grating modulation photoelectric gain. Background Technology

[0002] The mid-infrared band encompasses a wealth of information on molecular vibrational and rotational energy level transitions, reflecting the structural composition and energy state change characteristics of matter. Therefore, it holds significant application potential in fields such as spectral analysis, component identification, and dynamic signal detection. However, existing mid-infrared detectors still face several technical bottlenecks in practical applications:

[0003] First, it has low sensitivity and high noise. Mid-infrared materials typically have narrow band gaps and high intrinsic carrier concentrations at room temperature, which easily introduces thermally excited carriers, resulting in a significant superposition effect of thermal noise, dark current shot noise, and 1 / f flicker noise.

[0004] Secondly, the response mode is limited. Mainstream planar photoconductor structures typically employ a single carrier transport mode. Photogenerated carriers need to undergo long-distance lateral transport within the planar channel before being collected by the electrodes, resulting in a high recombination probability and slow response speed. Furthermore, the operating state is determined by fixed bias conditions, lacking the ability to actively control the carrier transport mechanism. Therefore, it is difficult to simultaneously address the differentiated detection needs of high-frequency transient signals and low-frequency slowly varying signals within the same device structure. For example, in dynamic physiological monitoring scenarios, existing devices struggle to flexibly switch between drift-dominated and diffusion-dominated transport mechanisms, making it impossible to simultaneously meet the requirements for high-temporal resolution acquisition of high-frequency physiological signals such as blood flow pulse waves, as well as the long-term stable monitoring needs of low-frequency slowly varying signals such as blood glucose and blood oxygen saturation.

[0005] Finally, the system has high power consumption. Traditional optical guide type mid-infrared detectors rely on continuous source-drain bias to maintain the carrier transport channel, resulting in high operating power consumption. Summary of the Invention

[0006] Purpose of the invention: The purpose of this invention is to provide a mid-infrared detection array based on grating modulation photoelectric gain, which enables flexible switching between fast response and high gain modes to meet the detection requirements of both high-frequency transient and low-frequency slowly varying signals. At the same time, it can improve the detection sensitivity of mid-infrared signals, reduce noise and dark current, and reduce the power consumption of the device.

[0007] Technical Solution: To achieve the above objectives, the present invention provides a mid-infrared detection array based on gate modulation photoelectric gain. The mid-infrared detection array is constructed on a flexible insulating substrate and includes a plurality of pixel units arranged in a periodic array. The pixel unit includes, from bottom to top, a gate, an insulating layer, a source, an active layer, and a drain. The active layer includes, in sequence, a lead selenide thin film, a two-dimensional molybdenum disulfide layer, and a black phosphorus quantum dot layer covering the source.

[0008] Preferably, both the source and drain electrodes are interdigitated and are symmetrically staggered in planar projection.

[0009] Preferably, the linewidth of the source and the drain is 2-4 μm, and the spacing between adjacent fingers is 2-4 μm.

[0010] Preferably, the lead selenide film has a thickness of 80–150 nm, the two-dimensional molybdenum disulfide layer has a thickness of 20–50 nm, and the black phosphorus quantum dot layer has a thickness of 10–40 nm.

[0011] Preferably, the substrate is a polyimide film or flexible glass.

[0012] Preferably, the drain electrode is a light-transmitting conductive material.

[0013] Preferably, the pixel unit forms a gate-controlled modulation path together with the gate, insulating layer and active layer: when the bias applied to the gate is in the range of -5V to -2V, drift transport dominates, exhibiting a fast response mode; when the bias applied to the gate is in the range of +2V to +5V, diffusion transport dominates, exhibiting a high gain mode.

[0014] Preferably, the method for preparing the pixel unit is as follows:

[0015] (1) Photoresist is spin-coated on the substrate, and a gate pattern is formed by exposure and development. Then, the gate is prepared by thermal evaporation and metal stripping processes.

[0016] (2) Photoresist is spin-coated onto the gate surface and hard-baked to form an insulating layer;

[0017] (3) Electrohydrodynamic jet printing technology is used to deposit conductive silver ink on the surface of the insulating layer to form the source electrode;

[0018] (4) A lead selenide thin film is formed on the source electrode using magnetron sputtering technology, and a protective gas is continuously introduced for annealing after film formation;

[0019] (5) Spin-coating the molybdenum disulfide dispersion onto the surface of the lead selenide film to form a two-dimensional molybdenum disulfide layer;

[0020] (6) Spin-coating the black phosphorus quantum dot dispersion onto the surface of the two-dimensional molybdenum disulfide layer, and then continuously introducing protective gas for curing to form a black phosphorus quantum dot layer;

[0021] (7) A double-layer CVD graphene is transferred onto the surface of the black phosphorus quantum dot layer and then patterned and developed to form a drain electrode.

[0022] Preferably, the molybdenum disulfide dispersion uses an alcohol-water mixed solvent as the exfoliation medium, and obtains a dispersion system containing two-dimensional molybdenum disulfide nanosheets through liquid phase shearing exfoliation and centrifugal fractionation extraction.

[0023] Preferably, the black phosphorus quantum dot dispersion is a dispersion system with isopropanol as the dispersion solvent and black phosphorus quantum dots as the solute, with a concentration of 0.1~0.2 mg / mL, wherein the black phosphorus quantum dots have a particle size of 1~15 nm and a monolayer rate of not less than 80%.

[0024] Beneficial effects: The present invention has the following advantages: 1. The mid-infrared detection array described in the present invention can achieve flexible switching between fast response and high gain mode by constructing a gate-controlled electric field and a heterojunction cooperative modulation mechanism, so as to take into account the detection requirements of high frequency transient and low frequency slowly changing signals, while effectively reducing the static power consumption and continuous operating power consumption of the mid-infrared detection array.

[0025] 2. Black phosphorus quantum dots, as a mid-infrared photosensitive material, can improve the absorption efficiency and photoelectric conversion efficiency per unit photon, thereby enhancing the response capability of the mid-infrared detection array to weak mid-infrared signals and improving detection sensitivity.

[0026] 3. By forming a double heterojunction structure through lead selenide thin film, two-dimensional molybdenum disulfide layer and black phosphorus quantum dot layer, noise is effectively reduced and dark current is suppressed, which improves the signal-to-noise ratio and output stability of mid-infrared detection array in mid-infrared detection process.

[0027] 4. The source and drain are respectively located at the bottom and top of the active layer. This vertical structure changes the transport direction of photogenerated carriers from long-distance lateral transmission in the plane to ultra-short-distance cross-layer transfer in the vertical direction at the nanometer scale. This reduces the recombination probability of carriers during transmission and improves the response rate of the mid-infrared detection array. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the hierarchical structure of the pixel unit in Example 1;

[0029] Figure 2 This is a schematic diagram of the three-dimensional structure of the pixel unit in Example 1;

[0030] Figure 3 This is a schematic diagram of the infrared detection array in Example 2;

[0031] Figure 4 This is a physical image of the infrared detection array in Example 2;

[0032] Figure 5 This is a partial optical microscope image of the interdigital electrode in Example 2;

[0033] Figure 6 This is a graph showing the transfer characteristics of the pixel unit in Example 2;

[0034] Figure 7This is a diagram showing the light pulse response characteristics of a pixel unit in Example 2;

[0035] Figure 8 This is a graph showing the response curves of a pixel unit under incident light of different polarization angles and wavelengths in Example 2.

[0036] Figure 9 This is a flowchart illustrating the fabrication process of the infrared detection array in Example 3;

[0037] Figure 10 This is a high-resolution transmission electron microscope image of the black phosphorus quantum dot dispersion in Example 3;

[0038] Figure 11 This is a schematic diagram of the multi-mode readout signal acquisition system composed of infrared detection arrays in Example 4;

[0039] Figure 12 This is a schematic diagram of the drug strength analysis of lansoprazole solutions of different concentrations at an incident wavelength of 2450 nm, based on the multi-mode readout signal acquisition system in Example 4.

[0040] Figure 13 This is a schematic diagram of the drug strength analysis of lansoprazole solutions of different concentrations at an incident wavelength of 2850 nm, based on the multi-mode readout signal acquisition system in Example 4.

[0041] Figure 14 This is a schematic diagram of the drug strength analysis of different concentrations of cefazolin sodium pentahydrate solution at an incident wavelength of 2450 nm, based on the multi-mode readout signal acquisition system in Example 4.

[0042] Figure 15 This is a schematic diagram illustrating the drug strength analysis of different concentrations of cefazolin sodium pentahydrate solution at an incident wavelength of 2850 nm using a multi-mode readout signal acquisition system in Example 4. Detailed Implementation

[0043] The technical solutions of this application will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0044] Example 1

[0045] This embodiment provides a mid-infrared detection array based on grating modulation photoelectric gain. The mid-infrared detection array is constructed on a flexible insulating substrate and includes a number of pixel units arranged in a periodic array.

[0046] The periodic array arrangement can be understood as an M-row N-column matrix layout, where M and N are both integers greater than 1.

[0047] The pixel units adopt a gated vertical stacking structure, such as Figure 1 As shown, from bottom to top, it includes: a gate on a flexible insulating substrate, an insulating layer covering the gate, an interdigitated source on the insulating layer, an active layer above the interdigitated source, and an interdigitated drain on the active layer; the active layer includes: a lead selenide thin film, a two-dimensional molybdenum disulfide layer, and a black phosphorus quantum dot layer sequentially covering the interdigitated source, and the interdigitated drain is disposed on the black phosphorus quantum dot layer.

[0048] The lead selenide thin film is used to absorb incident mid-infrared light and generate photogenerated carriers. Its thickness can be 80-150 nm, preferably 100 nm. The two-dimensional molybdenum disulfide layer is located between the lead selenide thin film and the black phosphorus quantum dot layer. It is used to promote the cross-interface transfer of photogenerated carriers. Its thickness can be 20-50 nm, preferably 35 nm. The black phosphorus quantum dot layer enhances mid-infrared absorption by utilizing the quantum confinement effect and participates in photoinduced charge accumulation and photoelectric gain modulation through its high specific surface area and interfacial charge regulation capability. It is an important functional layer for realizing high gain response of gate modulation. Its thickness can be 10-40 nm, preferably 30 nm.

[0049] To form an efficient vertical carrier collection channel between the interdigitated source and the interdigitated drain, in this embodiment, the interdigitated source and the interdigitated drain are located on different vertical levels, and are symmetrically and alternately distributed in planar projection, with the corresponding interdigitated regions arranged in a staggered manner. The interdigitated drain is formed of a light-transmitting conductive material, preferably graphene, to reduce the obstruction of incident light.

[0050] like Figure 2 The diagram shows a three-dimensional structure of the pixel unit. Preferably, the number of interdigitated source and drain electrodes is 20-50, and more preferably 30. Adjacent interdigitated electrodes are spaced apart and do not directly contact each other to form a carrier transport and collection region. Compared with conventional planar electrodes, the interdigitated structure in this embodiment can increase the effective contact interface, extend the charge collection boundary length, and promote the collection of photogenerated carriers, thereby improving the response sensitivity and detection performance of the pixel unit.

[0051] In this structure, heterojunction interfaces are formed between the lead selenide thin film and the two-dimensional molybdenum disulfide layer, and between the two-dimensional molybdenum disulfide layer and the black phosphorus quantum dot layer, respectively, constituting a longitudinal double heterojunction active structure.

[0052] The pixel unit forms a gate-controlled modulation path through a gate, an insulating layer, and an active layer. Applying an electric field to the gate via the insulating layer adjusts the band bending and carrier accumulation state at the dual heterojunction interface, thereby altering the separation, transport, and recombination behavior of photogenerated carriers. Under incident mid-infrared light irradiation, the lead selenide film and black phosphorus quantum dot layer absorb photons and generate photogenerated electron-hole pairs. The dual heterojunction interface synergistically promotes the interlayer transfer and rapid transport of photogenerated carriers. By adjusting the gate voltage, the built-in electric field distribution and the main carrier transport mode at the double heterojunction interface can be changed: when the gate is biased in the range of -5V to -2V, the built-in electric field at the double heterojunction interface is enhanced, and the photogenerated carriers generated in the black phosphorus quantum dot layer can be quickly separated under the synergistic effect of the built-in electric field and the gate electric field. Drift transport dominates, exhibiting a fast response mode, which is suitable for high-frequency transient signal acquisition. When the gate is biased in the range of +2V to +5V, the charge accumulation at the double heterojunction interface is enhanced, and the accumulation and modulation effect of photoinduced charge by the black phosphorus quantum dot layer is further enhanced. The effective lifetime of carriers is extended, and diffusion transport dominates, exhibiting a high-gain mode, which is suitable for weak signal and low-frequency slowly changing signal detection.

[0053] This embodiment enhances the separation, cross-layer transfer, and collection capabilities of photogenerated carriers through the synergistic effect of the vertical double heterojunction active structure and the gate-controlled modulation path, thereby improving device sensitivity and detection performance. Simultaneously, by adjusting the gate voltage to switch between fast response and high-gain modes, it can accommodate the differentiated detection requirements of high-frequency transient signals and low-frequency slowly weakening signals. Furthermore, the gate, through an insulating layer, modulates the band bending, built-in electric field, and charge accumulation state at the double heterojunction interface, helping to reduce the device's dependence on continuous source-drain bias, thereby reducing system power consumption.

[0054] Example 2

[0055] Based on Embodiment 1, this embodiment provides a mid-infrared detection array with a two-dimensional array structure composed of 4×4 pixel units, such as... Figure 3 The diagram shown is a schematic representation of the array structure. Figure 4 for Figure 3 A physical image of the array structure.

[0056] The mid-infrared detection array provided in this embodiment has a center-to-center spacing of 4 mm between adjacent pixel units. The thicknesses of the lead selenide film, the two-dimensional molybdenum disulfide layer, and the black phosphorus quantum dot layer in a single pixel unit are 100 nm, 35 nm, and 30 nm, respectively. The interdigitated source and interdigitated drain are arranged alternately, with 30 interdigitated dots.

[0057] like Figure 5The image shown is a partial optical microscope image of the interdigitated electrodes of the pixel unit. The image reveals a regular arrangement of the interdigitated structures, with a typical linewidth of 2–4 μm and a spacing of 2–4 μm between adjacent fingers, indicating good electrode patterning quality, consistent with the structural design of this embodiment.

[0058] To verify the grating modulation characteristics, dynamic light response characteristics, and polarization selection characteristics of a single pixel unit in this invention, a representative pixel unit from the mid-infrared detection array was selected as the test object, and electrical and optical response tests were conducted at room temperature.

[0059] like Figure 6 The figure shows the transfer characteristic curves and dark-state curves of the pixel unit described in this embodiment under zero source-drain bias and incident light power density of 65.23 mW / cm². During testing, the gate voltage of the pixel unit was scanned and the drain current was recorded to obtain the transfer characteristic curves under dark-state and different mid-infrared illumination conditions. As can be seen from the figure, under different wavelengths of illumination, the drain current of the device is significantly increased relative to the dark state, and a significant photocurrent modulation effect is exhibited near the threshold. This result shows that the gate electric field can effectively adjust the carrier distribution and channel conductance at the double heterojunction interface, enabling the device to achieve adjustable photoelectric gain under low bias conditions, thereby verifying the effectiveness of the mid-infrared detection array described in this invention in enhancing the response capability of weak mid-infrared signals, improving detection sensitivity, and reducing operating bias requirements. In particular, under higher gate voltage driving, significant charge accumulation occurs at the heterojunction interface, and diffusion transport dominates, resulting in extremely high photoconductivity gain of the device, verifying the high-gain mode of this invention.

[0060] like Figure 7 The figure shows the time-resolved optical pulse response characteristics of a single pixel unit under 2850nm pulsed light illumination. During testing, the device was periodically illuminated with pulsed modulated mid-infrared light, and the change in its output photocurrent over time was recorded. As can be seen from the figure, under multiple consecutive pulse cycles, the pixel unit output exhibits stable and repeatable rising and falling edges, and the photocurrent clearly switches between the on and off states. This result verifies the effectiveness of the mid-infrared detection array described in this invention in terms of rapid response, indicating that it can meet the detection requirements of high-frequency transient signals and provides a basis for achieving differentiated detection of high-frequency transient signals and low-frequency slowly weakening signals.

[0061] like Figure 8The figure shows the polar coordinate curves of the photoresponse of a single pixel unit under different mid-infrared bands and different incident polarization angles. During the test, the polarization angle of the incident linearly polarized light was changed under a fixed bias condition, and the photocurrent response at different wavelengths was recorded. To facilitate comparison of the device's polarization response characteristics under different bands, the measured polarized photocurrent was normalized, and the angle-dependent normalized photocurrent curve was plotted in polar coordinates. The normalized response was fitted using the following formula:

[0062]

[0063] in, Indicates the incident polarization angle. This represents the polarization response angle parameter obtained from the fitting. and These represent the maximum and minimum photocurrents, respectively. The polarization sensitivity of the device can be further obtained from the fitting results. .

[0064] The results show that the normalized polarization photocurrent curves of the device exhibit a distinct double-lobed distribution characteristic under different incident wavelengths, indicating that the pixel unit has significant polarization selectivity for incident mid-infrared light. Simultaneously, the polarization response angles differ for different wavelengths, indicating that the device's polarization response is related to the incident wavelength. This phenomenon arises because the coupling efficiency of the dual heterojunction to electromagnetic fields in different polarization directions varies, leading to different generation, separation, and transport efficiencies of photogenerated carriers under different polarization directions, thus manifesting as an anisotropic response of the photocurrent as the polarization angle changes. These results verify that the mid-infrared detection array described in this invention possesses polarization-selective detection capability and provide support for realizing multidimensional mid-infrared signal detection.

[0065] Example 3

[0066] like Figure 9 As shown, this embodiment provides a method for fabricating a mid-infrared detector array based on grating modulation photoelectric gain, including the following steps:

[0067] S1. Substrate pretreatment: The substrate is ultrasonically cleaned and dried sequentially with acetone, isopropanol and deionized water to obtain a clean surface.

[0068] S2. Forming the gate: Photoresist is spin-coated onto a cleaned flexible insulating substrate, and an elongated gate pattern is formed by exposure and development; then, a metal gate is prepared by thermal evaporation and metal stripping processes, wherein the metal gate material is preferably Au or Ag;

[0069] S3. Forming an insulating layer: The preferred material for the insulating layer is SU-8 photoresist. The SU-8 photoresist is spin-coated onto the gate surface in two steps using a spin coater. After hard curing at 200℃, an insulating layer with a thickness of 1~2μm is formed. The two spin-coating steps are as follows: the first step is at a speed of 1500rpm for 20s, and the second step is at a speed of 3000rpm for 60s.

[0070] S4. Source Electrode Patterning: The pattern of the interdigitated source electrode is pre-designed by CAD and imported into the printing control system. The printing control system uses electrohydrodynamic jet printing technology to deposit conductive silver ink on the surface of the insulating layer to form the interdigitated source electrode. Before printing, the printing needle is pre-installed and silver ink is added. The position of the needle is adjusted so that the tip of the needle can be clearly observed by the imaging system, and the needle is kept 1mm away from the substrate surface. During the printing process, a square wave drive mode is used with a drive frequency of 200Hz, a pulse duty cycle of 15%, and a drive amplitude of 1000. After printing, the interdigitated source electrode is formed by annealing.

[0071] S5. Lead selenide thin film deposition: A 100 nm thick lead selenide thin film was formed using magnetron sputtering. Sputtering was performed in a high-purity argon atmosphere with a purity ≥ 99.99%, and the substrate vacuum degree of the target chamber was ≤ 5 × 10⁻⁶. -5 Pa, working pressure 0.1~1Pa, sputtering power 30~100W, after film formation, anneal at 200℃ for about 60min in a protective atmosphere of continuously purifying 99.999% high-purity nitrogen to stabilize electrical properties;

[0072] S6. Formation of a two-dimensional molybdenum disulfide layer: A molybdenum disulfide dispersion was obtained by liquid phase exfoliation and then spin-coated onto the surface of a lead selenide film to form a two-dimensional molybdenum disulfide layer with a thickness of 35 nm. The spin-coating was carried out in two stages: the first stage was spin-coating at 2000 rpm for 10 s, and the second stage was spin-coating at 2500 rpm for 50 s. Subsequently, the film was annealed at 250 °C for 45 min in a protective atmosphere with a continuous flow of 99.999% high-purity nitrogen. The molybdenum disulfide dispersion could be prepared by a 1:1 volume ratio of alcohol / water mixed solvent, subjected to high-speed shearing for about 60 min, and centrifuged at 5000 rpm for 60 min, and the supernatant was collected.

[0073] S7. Black phosphorus quantum dot layer film formation: A black phosphorus quantum dot layer with a thickness of 30 nm is formed by spin coating a black phosphorus quantum dot dispersion. The process is carried out in two stages: the first stage is spin coating at 1500 rpm for 15 s, and the second stage is spin coating at 3000 rpm for 45 s. After spin coating, the layer is cured at 100 °C in a protective atmosphere with a continuous flow of 99.999% high-purity nitrogen. The black phosphorus quantum dot dispersion uses isopropanol (IPA) as the dispersion solvent. The black phosphorus quantum dot particle size is 1-15 nm, the monolayer ratio is not less than 80%, and the dispersion concentration is about 0.1 mg / mL.

[0074] S8. Drain patterning: A double-layer CVD graphene is transferred onto the surface of the black phosphorus quantum dot layer. Then, the CVD graphene film is patterned and developed using oxygen plasma with a power of 50W to form an interdigitated drain. The interdigitated drain and the interdigitated source are located on different layers. The two are symmetrically distributed in the overall planar projection, and the corresponding interdigitated regions are misaligned.

[0075] like Figure 10 The image shown is a high-resolution transmission electron microscope image of a black phosphorus quantum dot dispersion. The dashed elliptical boxes in the image indicate the lattice regions of the black phosphorus quantum dots, which exhibit large-area, continuous, and clear atomic lattice fringes. The interplanar spacings were measured to be approximately 0.446 nm (001) plane family and 0.26 nm (040) plane family, respectively, indicating that the black phosphorus quantum dots have good crystallinity and a layered ordered structure. This structural feature is beneficial for the stable absorption of mid-infrared incident light by the black phosphorus quantum dot layer and the generation of photogenerated carriers. It also facilitates the formation of a low-defect heterojunction interface with the two-dimensional molybdenum disulfide layer, thereby reducing interfacial recombination and promoting the transfer of carriers from the lead selenide film and the black phosphorus quantum dot layer to the two-dimensional molybdenum disulfide layer and the interdigitated source direction.

[0076] This embodiment combines electrohydrodynamic jet printing with CVD graphene non-destructive transfer etching to construct an interdigitated source-drain architecture located in a vertical three-dimensional space with a staggered arrangement. This structure transforms the transport of photogenerated carriers from micrometer-scale planar lateral drift to nanometer-scale vertical interlayer transfer, greatly shortening the carrier transport path and suppressing carrier recombination during transport, thereby significantly improving the device's photogenerated charge collection efficiency and response sensitivity.

[0077] Example 4

[0078] like Figure 11 As shown, this embodiment provides a multi-mode readout signal acquisition system based on the mid-infrared detection array of the present invention. This system uses the mid-infrared detection array as the core unit, combined with a multi-band laser source module, a grid voltage modulation module, an analog signal conditioning module, an analog-to-digital conversion module, and a host computer data processing module, to achieve parallel acquisition and analysis of multi-component target signals.

[0079] The multi-band laser source module can output multiple mid-infrared lasers of different wavelengths for multi-band irradiation of the object under test. Preferably, the multi-band laser source module includes four mid-infrared light sources, each corresponding to a different detection band. Each band of laser light is coupled optically and then irradiates the object under test. The mid-infrared light passing through the object then enters the detection array, thereby acquiring the response information of the object under test under different wavelength conditions. For multi-component detection scenarios, different components typically have different absorption characteristics in different mid-infrared bands. Therefore, the multi-band laser source module can be used to excite the object under test, and the detection array can simultaneously acquire multi-band response signals, thereby achieving parallel identification and analysis of multiple components.

[0080] In the detection array, each pixel unit shares row gate lines and column readout lines. The row direction is used to load the gate modulation signal, and the column direction is used to output the pixel response current. The gate voltage modulation module generates multiple gate voltage control signals, which are applied to the gate lines of different rows of the array according to a preset timing sequence via analog switches, thereby forming multiple independently adjustable working regions in space. Different regions can be loaded with different gate voltage conditions according to the detection target, so that the detection array operates in different response modes, in order to meet the requirements of rapid acquisition of high-frequency transient signals and high-sensitivity detection of low-frequency slowly weakening signals.

[0081] In the column readout direction, the photocurrent signals output by each column of pixels on the array are sent to the front-end analog signal conditioning module. The analog signal conditioning module includes a transimpedance amplifier to convert the weak photocurrent into a voltage signal; if necessary, it can also be combined with a differential amplifier stage or a phase-locked loop (PLL) processing unit to improve weak signal detection capability. The conditioned multi-channel analog signals are input to a multi-channel analog-to-digital converter and transmitted to a host computer for display, storage, and feature extraction, thereby obtaining multi-dimensional response information corresponding to different bands, different grid voltages, and different array regions.

[0082] After the detector array is illuminated by multi-band mid-infrared light from the target object, the lead selenide thin film and black phosphorus quantum dot layer in the pixel unit absorb incident photons and generate photogenerated carriers. The heterojunction formed between the two-dimensional molybdenum disulfide layer and the black phosphorus quantum dot layer facilitates the cross-interface transfer and longitudinal transport of photogenerated carriers. Simultaneously, the gate voltage modulation module modulates the band bending, built-in electric field distribution, and carrier accumulation region at the heterojunction interface by changing the bias conditions on the gates of each partition, thereby altering the device's primary transport mechanism. Furthermore, in multi-component drug detection applications, different drug components exhibit different absorption characteristics in different mid-infrared bands, while the same component displays different signal intensities and dynamic characteristics under different gate voltage operating modes. Therefore, the system described in this embodiment can simultaneously introduce multi-band light source information and multi-gate voltage mode information into the array readout process. By jointly analyzing the output signals of each channel, it achieves simultaneous identification, quantitative analysis, and low-power continuous monitoring of dynamic changes in multiple drug components.

[0083] Furthermore, the multi-mode readout signal acquisition system described in this embodiment can also be extended to physiological monitoring scenarios. In this scenario, by applying different grid voltage biases to different regions, the same detector array can operate in a state suitable for rapid response and a state suitable for high-gain detection, thereby meeting the requirements for high-temporal resolution acquisition of high-frequency physiological signals such as blood flow pulse waves, as well as the requirements for high-sensitivity monitoring of low-frequency slowly varying signals such as changes in blood glucose and blood oxygen saturation.

[0084] This embodiment further uses the detection of drug liquid components as an example. Figure 12 and Figure 13 The results show the response intensity analysis of lansoprazole solutions of different concentrations at incident wavelengths of 2450nm and 2850nm. The measurement data in the area marked by the blue dashed box shows that the output signal exhibits a characteristic concave response waveform of "first decreasing and then rising" with the sampling point sequence, and there is a clear minimum response extreme point. The amplitude of the minimum response extreme point of lansoprazole solutions of different concentrations is significantly different. Figure 14 and Figure 15 The results show the response intensity analysis of cefazolin sodium pentahydrate solutions at incident wavelengths of 2450 nm and 2850 nm, respectively. The output signal within the blue dashed box also exhibits a concave waveform with a fixed shape. Further comparison... Figures 12 to 15 The data shows that the minimum response extreme points also differ among different drug solution samples. These results indicate that the mid-infrared detection array described in this invention can produce identifiable characteristic responses to different drug solution components and their concentration changes, thereby achieving effective differentiation of different drug solution components and their concentrations.

Claims

1. A mid-infrared detection array based on grating modulation photoelectric gain, wherein the mid-infrared detection array is constructed on a flexible insulating substrate, characterized in that, It includes a number of pixel units arranged in a periodic array, and the pixel unit includes, from bottom to top, a gate, an insulating layer, a source, an active layer, and a drain; the active layer includes, in sequence, a lead selenide thin film, a two-dimensional molybdenum disulfide layer and a black phosphorus quantum dot layer covering the source. Both the source and drain electrodes are interdigitated and symmetrically staggered in planar projection. The lead selenide film has a thickness of 80–150 nm, the two-dimensional molybdenum disulfide layer has a thickness of 20–50 nm, and the black phosphorus quantum dot layer has a thickness of 10–40 nm.

2. The mid-infrared detection array according to claim 1, characterized in that, The linewidth of the source and the drain is 2-4 μm, and the distance between adjacent fingers is 2-4 μm.

3. The mid-infrared detection array according to claim 1, characterized in that, The substrate is a polyimide film or flexible glass.

4. The mid-infrared detection array according to claim 1, characterized in that, The drain electrode is a light-transmitting and conductive material.

5. The mid-infrared detection array according to claim 1, characterized in that, The pixel unit forms a gate-controlled modulation path together with the gate, insulating layer and active layer: when the bias applied to the gate is in the range of -5V to -2V, drift transport dominates, exhibiting a fast response mode; when the bias applied to the gate is in the range of +2V to +5V, diffusion transport dominates, exhibiting a high gain mode.

6. The mid-infrared detection array according to any one of claims 1 to 5, characterized in that, The method for preparing the pixel unit is as follows: (1) Photoresist is spin-coated on the substrate, and a gate pattern is formed by exposure and development. Then, the gate is prepared by thermal evaporation and metal stripping processes. (2) Photoresist is spin-coated onto the gate surface and hard-baked to form an insulating layer; (3) Electrohydrodynamic jet printing technology is used to deposit conductive silver ink on the surface of the insulating layer to form the source electrode; (4) A lead selenide thin film is formed on the source electrode using magnetron sputtering technology, and a protective gas is continuously introduced for annealing after film formation; (5) Spin-coating the molybdenum disulfide dispersion onto the surface of the lead selenide film to form a two-dimensional molybdenum disulfide layer; (6) Spin-coating the black phosphorus quantum dot dispersion onto the surface of the two-dimensional molybdenum disulfide layer, and then continuously introducing protective gas for curing to form a black phosphorus quantum dot layer; (7) A double-layer CVD graphene is transferred onto the surface of the black phosphorus quantum dot layer and then patterned and developed to form a drain electrode.

7. The mid-infrared detection array according to claim 6, characterized in that, The molybdenum disulfide dispersion was obtained by using an alcohol-water mixed solvent as the exfoliation medium and undergoing liquid-phase shearing and centrifugal fractionation to obtain a dispersion system containing two-dimensional molybdenum disulfide nanosheets.

8. The mid-infrared detection array according to claim 6, characterized in that, The black phosphorus quantum dot dispersion is a dispersion system with isopropanol as the dispersion solvent and black phosphorus quantum dots as the solute, with a concentration of 0.1~0.2 mg / mL. The black phosphorus quantum dots have a particle size of 1~15 nm and a monolayer rate of not less than 80%.

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