Photoelectric detector based on grating structure and photoelectric detection method

Abstract

The invention relates to the field of photoelectric detection, and discloses a photoelectric detector based on a grating structure and a photoelectric detection method.The photoelectric detector comprises a substrate layer and a photoelectric material layer, and the photoelectric material layer comprises a metal grating structure, a first electrode, a second electrode, a first photoelectric confinement material and a second photoelectric confinement material; the metal grating structure comprises a first metal grating and a second metal grating, the first photoelectric confinement material and the second photoelectric confinement material are connected, and a depletion junction region is formed at an interface; the first metal grating and the second metal grating are symmetrically arranged on two sides of the depletion junction region and are used for exciting a plasmon mode to form a local light field; the first electrode is connected with the first photoelectric confinement material, the second electrode is connected with the second photoelectric confinement material, and the first electrode and the second electrode are used for extracting photon-generated carriers. According to the technical scheme provided by the invention, the separation efficiency of photon-generated carriers and the response performance of the photoelectric detector can be improved.

Description

Technical Field

[0001] This application relates to the field of photoelectric detection, and in particular to a photoelectric detector and photoelectric detection method based on a grating structure. Background Technology

[0002] Currently, infrared photodetectors based on the photoelectric transition principle have attracted much attention due to their high absorption efficiency in the infrared band, and have important application value in fields such as meteorological monitoring, remote sensing imaging, astronomical observation and military reconnaissance.

[0003] In traditional infrared detectors, photogenerated carriers are mainly generated in the neutral region and need to diffuse to the depletion region by a concentration gradient before they can be effectively separated under the influence of a built-in electric field. This diffusion process takes a long time, and during this period, carriers are very prone to recombination. The separation efficiency of photogenerated carriers is low, resulting in a slow response speed of the photodetector. Furthermore, under room temperature conditions, dark current is easily generated due to thermal excitation, leading to poor detector response performance.

[0004] Therefore, improving the separation efficiency of photogenerated carriers is a key research focus for achieving high response performance in photodetectors. Summary of the Invention

[0005] This application provides a photodetector and photodetector method based on a grating structure, which can improve the separation efficiency of photogenerated carriers, enabling the photodetector to have a high response speed, thereby improving the response performance of the photodetector.

[0006] The first aspect of this application provides a photodetector based on a grating structure. The photodetector includes a substrate layer and a photoelectric material layer. The photoelectric material layer includes a metal grating structure, a first electrode, a second electrode, a first photoelectric confinement material, and a second photoelectric confinement material. The metal grating structure includes a first metal grating and a second metal grating. The first and second photoelectric confinement materials are in contact, and a depletion junction region is formed at their interface. The first and second metal gratings are symmetrically disposed on both sides of the depletion junction region. The metal grating structure is used to excite plasmon modes using infrared light of a specific wavelength to form a local optical field based on the plasmon modes. The first electrode is in contact with the first photoelectric confinement material, and the second electrode is in contact with the second photoelectric confinement material. The first and second electrodes are used to extract photogenerated carriers.

[0007] In one implementation, the local optical field overlaps with the depleted junction region space.

[0008] In one embodiment, a built-in electric field is distributed within the depletion junction region, the width of which matches the local optical field.

[0009] In one embodiment, the depleted junction region is used to generate the photogenerated carriers under the influence of the local optical field.

[0010] In one embodiment, the depletion junction is further configured to separate the photogenerated carriers into electrons and holes under the influence of the built-in electric field.

[0011] In one embodiment, the first photocontainment material is doped with P-type doping and the second photocontainment material is doped with N-type doping.

[0012] In one embodiment, the doping concentration of both the first photocontainment material and the second photocontainment material is 1×10⁻⁶. 16 cm -3 .

[0013] In one embodiment, the photodetector operates at a temperature of 150K.

[0014] A second aspect of this application provides a photoelectric detection method based on a grating structure. The method uses the photoelectric detector described in the first aspect. The method includes: exciting a plasmonic mode of a metal grating structure; constraining the light field energy to a specific location based on the transmission characteristics of the plasmonic mode to form a local light field at the specific location; adjusting the horizontal width and channel width of the depletion junction region to make the depletion junction region spatially overlap with the local light field; receiving the light field energy in the depletion junction region to generate photogenerated carriers, which are separated into electrons and holes under the action of a built-in electric field; extracting the holes through a first electrode and extracting the electrons through a second electrode to form a photoelectric response signal in an external circuit connected by the first and second electrodes.

[0015] In one embodiment, adjusting the horizontal width of the depletion junction region and the channel width includes: applying a specified gate voltage to the first photocontainment material or the second photocontainment material, adjusting the Fermi level difference between the first photocontainment material and the second photocontainment material by means of the specified gate voltage, thereby adjusting the horizontal width of the depletion junction region; and adjusting the channel width of the first photocontainment material and the second photocontainment material to change the channel width of the depletion junction region.

[0016] The technical solution provided in one or more embodiments of this application overlaps the local optical field with the depletion junction region, enabling photogenerated carriers to be "generated and separated simultaneously," thus improving the separation efficiency of photogenerated carriers. Specifically, a local optical field is formed by exciting plasmon modes through a metal grating structure in the photoelectric material layer, and this local optical field overlaps with the depletion junction region. Photogenerated carriers are concentrated under the action of the local optical field and rapidly separated under the action of the built-in electric field, so as to be extracted by the electrodes to form a photoelectric response signal. At the same time, by adjusting the horizontal width and channel width of the depletion junction region, the distribution of the built-in electric field is made more uniform, and it overlaps with the spatial height of the local optical field, thereby optimizing the generation and separation efficiency of photogenerated carriers and improving the response performance of the photodetector. In addition, by designing a narrower channel width and reverse bias, the entire photoelectric confinement material can be almost covered by the depletion junction region, thereby further improving the separation efficiency of photogenerated carriers and reducing the probability of carriers generating dark current through recombination mechanisms.

[0017] It is evident that the technical solution provided in this application can improve the separation efficiency of photogenerated carriers, enabling the photodetector to have a high response speed, while suppressing the generation of dark current, thereby improving the response performance of the photodetector. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the specific embodiments of this application or the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0019] Figure 1 A schematic diagram of a photodetector based on a grating structure provided for embodiments of this application; Figure 2 A schematic diagram showing the location of a local optical field and a depletion junction region provided for one embodiment of this application; Figure 3 A diffusion diagram illustrating carrier separation provided in one embodiment of this application; Figure 4(a) is a schematic diagram of the relationship between dark current and voltage provided in an embodiment of this application; Figure 4(b) is a schematic diagram of the distribution of the built-in electric field under different reverse bias voltages provided in an embodiment of this application; Figure 5(a) is a schematic diagram showing the change in the separation efficiency of photogenerated carriers under reverse bias according to an embodiment of this application; Figure 5(b) is a schematic diagram showing the change in the separation efficiency of photogenerated carriers under different photoelectric confinement material lengths provided in an embodiment of this application; Figure 5(c) is a schematic diagram showing the change in the separation efficiency of photogenerated carriers under different optoelectronic confinement material widths according to an embodiment of this application; Figure 6 A schematic diagram illustrating the steps of a photoelectric detection method based on a grating structure, provided as one embodiment of this application; Figure 7 This is a structural schematic diagram of the horizontal width of the depletion junction region and the channel width provided in one embodiment of this application.

[0020] Explanation of reference numerals in the attached figures 10 - Substrate layer, 20 - Optoelectronic material layer, 21 - Metal grating structure, 211 - First metal grating, 212 - Second metal grating, 22 - First electrode, 23 - Second electrode, 24 - First optoelectronic confinement material, 25 - Second optoelectronic confinement material, 30 - Localized optical field, 31 - Depletion junction region, 32 - Neutral region. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0022] Furthermore, the use of terms such as "first," "second," etc., in this application is for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of embodiments in this application, unless otherwise stated, "multiple" means two or more. Additionally, the use of "based on" or "according to" implies openness and inclusiveness, because processes, steps, calculations, or other actions "based on" or "according to" one or more of the stated conditions or values ​​may in practice be based on additional conditions or beyond the stated values.

[0023] With the continuous development of the industry, infrared detectors play a crucial role in many fields such as meteorological monitoring, remote sensing imaging, astronomical observation, military reconnaissance, and industrial inspection. Their performance directly affects the technological development and application effectiveness in these fields. An ideal infrared detector should possess high sensitivity, fast response, low noise, and the ability to operate stably at or near room temperature. However, existing infrared detection technologies still face many challenges in these aspects.

[0024] In related technologies, existing photodetectors have low photogenerated carrier separation efficiency. Photogenerated carriers are mainly generated in the neutral region of the photodetector and require diffusion through a concentration gradient to the depletion region before they can be effectively separated under the influence of a built-in electric field. This diffusion process is time-consuming, and during the migration of photogenerated carriers, they easily recombine with defect states within the material, further reducing the detector's sensitivity and response speed.

[0025] Furthermore, especially in narrow bandgap infrared optoelectronic devices, the intrinsic carrier concentration increases significantly at room temperature due to thermal excitation and other reasons, resulting in a substantial increase in background noise and the generation of dark current. Moreover, it is difficult to effectively separate photogenerated carriers from carriers generated by background noise, which seriously affects the signal-to-noise ratio of the photodetector, thereby reducing the sensitivity and resolution of the photodetector. This forces the photodetector to operate only in low-temperature environments, severely limiting its performance.

[0026] In view of this, existing infrared detectors have significant shortcomings in terms of separation of photogenerated carriers and background noise, carrier separation efficiency, and operating temperature range. This application provides one or more embodiments of a photodetector and photodetection method based on a grating structure, which can solve the above problems, improve the separation efficiency of photogenerated carriers, enable the photodetector to have a high response speed, and suppress the generation of dark current, thereby improving the response performance of the photodetector.

[0027] Please see Figure 1 One embodiment of this application provides a photodetector based on a grating structure. The photodetector includes a substrate layer 10 and a photoelectric material layer 20. The photoelectric material layer includes a metal grating structure 21, a first electrode 22, a second electrode 23, a first photoelectric confinement material 24, and a second photoelectric confinement material 25. The metal grating structure includes a first metal grating 211 and a second metal grating 212, wherein: The first photoelectric confinement material 24 and the second photoelectric confinement material 25 are connected, wherein the first photoelectric confinement material 24 and the second photoelectric confinement material 25 form a depletion junction region at the interface; The first metal grating 211 and the second metal grating 212 are symmetrically arranged on both sides of the depletion junction region. The metal grating structure 21 is used to excite plasmon modes with infrared light of a specific wavelength to form a local optical field based on the plasmon modes. The first electrode 22 is connected to the first photoelectric confinement material 24, and the second electrode 23 is connected to the second photoelectric confinement material 25. The first electrode 22 and the second electrode 23 are used to extract photogenerated carriers.

[0028] In this embodiment, the depletion junction region can be understood as a space charge region naturally formed at the interface due to carrier diffusion and recombination after the P-type and N-type photocontainment materials come into contact. Specifically, due to the different doping types of the first photocontainment material 24 and the second photocontainment material 25, there is a significant difference in the concentration of carriers (electrons and holes) on both sides of the interface, which causes carrier diffusion and forms a region of positive and negative charge separation near the interface. The mobile carriers in the region are almost completely consumed by recombination, thus forming a depletion junction region. Generally, a built-in electric field is generated simultaneously during the formation of the depletion junction region. The depletion junction region is used to separate photogenerated carriers under the action of the built-in electric field and to cause the separated carriers to drift to the electrodes on both sides.

[0029] In this embodiment, the aforementioned metal grating structure 21 employs an inverted, periodically arranged first metal grating 211 and second metal grating 212, enabling resonant coupling with infrared light of a specific wavelength to excite plasmonic modes. These plasmonic modes can be understood as various collective oscillation modes generated by the interaction of free electrons in a metal or specific material with light, exhibiting characteristics of localized spatial localization. Specifically, the first metal grating 211 and second metal grating 212 employ specific micro / nano structures. Infrared photons to be detected are irradiated onto the first metal grating 211 and second metal grating 212. By designing the grating's arrangement period and structure, resonant coupling with infrared light of a specific wavelength is achieved, thereby exciting plasmonic modes in the first metal grating 211 and second metal grating 212. This localizes the freely propagating infrared light within a specific spatial region, forming a localized optical field. For example, in the depletion junction region, the localized optical field of the plasmonic mode allows photogenerated carriers to be primarily generated in the depletion junction region. The aforementioned local optical field can significantly enhance the interaction between light and matter, and improve the generation efficiency of photogenerated carriers.

[0030] In one implementation, please refer to Figure 2By spatially overlapping the localized optical field 30 with the depletion junction region 31, photogenerated carriers are concentrated in the depletion junction region 31, accelerating the generation and transmission efficiency of photogenerated carriers. In traditional nonlocalized optical field methods, when light propagates in a semiconductor, the energy is relatively uniformly distributed, and the effective area is relatively large. Some photogenerated carriers are generated in the neutral region of the first photoelectric confinement material 24 and the second photoelectric confinement material 25. These photogenerated carriers need to diffuse to the depletion junction region 31 for separation. The slow diffusion process leads to a slow response speed and easy recombination. However, the localized optical field 30 of the metal grating-excited plasmon is precisely designed at the position of spatial overlap with the depletion junction region 31. Infrared light is strongly absorbed here, efficiently generating electron-hole pairs, i.e., photogenerated carriers. By localizing the optical field to the depletion junction region 31, the generation location of photogenerated carriers is concentrated in the depletion junction region 31, eliminating the need for additional diffusion to the depletion junction region, thereby accelerating the transmission efficiency of photogenerated carriers and improving the response speed of the photodetector.

[0031] In one implementation, please refer to Figure 3 A built-in electric field is distributed within the aforementioned depletion junction region 31, and the width of the built-in electric field matches the local optical field 30. Since the depletion junction region 31 and the local optical field 30 are located in the same region, and the built-in electric field is distributed within the depletion junction region 31 and matches the local optical field 30, when photogenerated carriers are generated within the depletion junction region 31, they are immediately separated under the action of the built-in electric field. The photogenerated carriers are separated into electrons and holes, which then rapidly move towards the electrodes on both sides by drifting, generating photoelectric signals through the external circuit connected to the electrodes. Compared to the traditional method where carriers generated in the neutral region 32 need to slowly diffuse to the depletion junction region 31 before separation, the photogenerated carriers in this embodiment can achieve a rapid process optimization in terms of generation and separation when the depletion junction region 31, the built-in electric field, and the local optical field 30 overlap. Under the action of the built-in electric field, they quickly drift to the electrodes on both sides, which greatly accelerates the generation efficiency, separation efficiency, and transmission efficiency of photogenerated carriers, thereby improving the response speed of the photodetector and making the photodetector more sensitive.

[0032] In this embodiment, the first photocontainment material 24 is p-type doped, with holes as the primary charge carrier, and the second photocontainment material 25 is n-type doped, with holes as the primary charge carrier. The built-in electric field is generated by the formation of a depletion junction region. Specifically, when the first photocontainment material 24 and the second photocontainment material 25 are in close contact, due to the carrier concentration gradient, during the depletion junction region and the generation of the built-in electric field, electrons diffuse into the first photocontainment material 24, leaving behind immobile positively charged ionized donors; similarly, holes diffuse into the second photocontainment material 25, leaving behind negatively charged ionized acceptors. This forms a depletion junction region 31 composed of positive and negative ions near the interface, and generates a built-in electric field within the depletion junction region 31 pointing from the second photocontainment material 25 to the first photocontainment material 24, thereby preventing further diffusion of charge carriers.

[0033] Furthermore, in the separation stage of photogenerated carriers, the photogenerated carriers are separated into electrons and holes under the action of the built-in electric field. The electrons are rapidly drifted to the second electrode 23 through the second photoelectric confinement material 25 under the action of the built-in electric field, and the holes are rapidly drifted to the first electrode 22 through the first photoelectric confinement material 24 under the action of the built-in electric field. Since the first photoconductive confinement material 24 is P-type doped, its Fermi level is closer to the valence band, and the second photoconductive confinement material 25 is N-type doped, its Fermi level is closer to the conduction band. When an electron in the valence band receives energy from the localized light field, it will jump from the valence band to the conduction band and become a freely moving, negatively charged electron. When the electron leaves the valence band, it leaves a vacancy in the valence band as a positively charged hole. This pair of electrons and holes is called photogenerated carriers. The built-in electric field is used to separate the electrons and holes, apply an electric field to the electrons to make them drift to the second electrode 23, and apply an electric field to the holes to make them drift to the first electrode 22.

[0034] In this embodiment, the built-in electric field causes the separated electrons and holes to drift rapidly to both sides, preventing them from recombinating again. If electrons and holes are very close, electrons in the conduction band may fall back into holes in the valence band. By matching the width of the built-in electric field to the local optical field, electrons and holes are immediately separated from the generated photogenerated carriers. Opposite forces are applied to electrons and holes with different charges, causing them to move rapidly towards the electrodes on both sides. This achieves instantaneous and efficient separation, greatly improving the separation efficiency of photogenerated carriers and enhancing the response performance of the photodetector.

[0035] In one embodiment, the doping concentration of both the first photocontainment material and the second photocontainment material is 1×10⁻⁶. 16 cm -3The ambient temperature of the photodetector is 150K. In the depletion junction region, photogenerated carriers rapidly separate under the influence of the built-in electric field. An appropriate doping concentration ensures sufficient width and built-in electric field strength in the depletion junction region for efficient carrier separation. Meanwhile, in the absence of external optical signals, high doping concentration increases the intrinsic carrier concentration; lowering the operating temperature to 150K significantly reduces the intrinsic carrier concentration, thereby reducing dark current. A 1×10⁻⁶ doping density is selected. 16 cm -3 The doping concentration and operating temperature of 150K ensure that the depleted junction region has sufficient built-in electric field strength to quickly separate photogenerated carriers, while avoiding excessive dark current, thus achieving a balance between sensitivity and noise.

[0036] In one embodiment, the first photoelectric confinement material is p-type doped with a doping concentration of 1×10⁻⁶. 16 cm -3 The second photoelectric confinement material is N-type doped with a doping concentration of 1×10⁻⁶. 16 cm -3 The ambient temperature was 150K. The length of both the first and second photoelectric confinement materials was 0.5 μm, and the width was 0.02 μm. Due to the extremely narrow photoelectric confinement width, there was an extremely low dark current under reverse bias.

[0037] In this embodiment, please refer to Figures 4(a) and 4(b). Figure 4(a) shows the relationship between dark current and voltage. The device dark current varies with voltage. Under zero bias, the device dark current is low due to the narrow photocontainment width. Furthermore, the narrow width of the photocontainment material results in an extremely low dark current under reverse bias, eliminating the need for extreme deep cooling of the detector. Figure 4(b) shows the distribution of the built-in electric field in the depletion junction region at reverse biases of 0V and -0.1V. Under 0V bias, the intensity of the built-in electric field is low, while under -0.1V bias, the intensity of the built-in electric field increases significantly. This is because the reverse bias enhances the built-in electric field, improving carrier separation efficiency and thus enhancing the performance of the photodetector, such as sensitivity and response speed.

[0038] In this embodiment, please refer to Figures 5(a), 5(b), and 5(c). Figure 5(a) shows the change in the separation efficiency of photogenerated carriers under reverse bias. That is, under reverse bias, the separation efficiency can be maintained at a very high value, which means that more photogenerated carriers can be successfully separated from the depletion region and collected by the electrodes, thereby improving the intensity of the photoelectric response signal. Figure 5(b) shows the change in the separation efficiency of photogenerated carriers under different photoelectric confinement material lengths. Within a certain range, the length change has little effect on the separation efficiency. Figure 5(c) shows the change in the separation efficiency of photogenerated carriers under different photoelectric confinement material widths. The separation efficiency will show obvious oscillations at a specific width value, that is, the separation efficiency will fluctuate significantly with the change of width. When designing a photodetector, the width W needs to be carefully selected.

[0039] Please see Figure 6 This application also provides a photoelectric detection method based on a grating structure, which is applied to the above-mentioned photoelectric detector based on a grating structure. The method includes the following steps: S1: Excite the plasmonic mode of the metal grating structure, and constrain the light field energy to a specific location based on the transmission characteristics of the plasmonic mode, so as to form a local light field at the specific location. S3: Adjust the horizontal width and channel width of the depletion junction region so that the depletion junction region spatially overlaps with the local optical field; S5: The depletion junction region receives optical energy to generate photogenerated carriers, which are then separated into electrons and holes under the action of the built-in electric field. S7: The holes are extracted through the first electrode and the electrons are extracted through the second electrode to form a photoelectric response signal in the external circuit connected by the first electrode and the second electrode.

[0040] In this embodiment, when infrared light of a specific wavelength irradiates the metal grating structure, free electrons in the metal interact with photons, exciting plasmon modes. These plasmon modes have the ability to localize the light field energy near the metal surface. By designing the metal grating structure, the light field energy can be confined to a specific location in the photoelectric confinement material, forming a localized light field. This localized light field can significantly enhance the interaction between light and matter, improve the generation efficiency of photogenerated carriers, and simultaneously control the concentration of photogenerated carriers at that specific location.

[0041] In this embodiment, the horizontal width of the depletion junction and the channel width are key parameters affecting the separation efficiency of photogenerated carriers. By adjusting these parameters, spatial overlap between the depletion junction and the local optical field can be ensured. Specifically, when the depletion junction and the local optical field spatially overlap, photogenerated carriers are mainly generated within the depletion junction. Due to the built-in electric field within the depletion junction, these photogenerated carriers can separate rapidly under the influence of the built-in electric field, reducing the recombination probability of carriers and improving the detector's sensitivity and response speed.

[0042] In this embodiment, when the energy of the local optical field is received by the depleted junction region, the photon energy excites electrons to transition from the valence band to the conduction band, thereby generating photogenerated carriers within the depleted junction region. Furthermore, a built-in electric field exists within the depleted junction region, which can rapidly separate the photogenerated carriers into electrons and holes. Electrons are pushed towards the first photoelectric confinement material characterizing the N-type region, and holes are pushed towards the second photoelectric confinement material characterizing the P-type region, thereby reducing the residence time of carriers within the depleted junction region and further improving the carrier separation efficiency.

[0043] In this embodiment, the separated holes and electrons are extracted by the first electrode and the second electrode, respectively. Specifically, the first electrode is connected to the first photocontainment material to extract holes, and the second electrode is connected to the second photocontainment material to extract electrons. The carriers extracted to the electrodes form a current signal, which is amplified and processed by external circuitry to ultimately output a measurable electrical signal. This electrical signal reflects the intensity and characteristics of the incident light, thereby achieving photodetection. By optimizing the localization of the light field and the structure of the depletion junction, the generation and separation efficiency of photogenerated carriers are significantly improved, thereby enhancing the sensitivity and response speed of the photodetector.

[0044] In one implementation, please refer to Figure 7 The spatial overlap between the depletion junction region 31 and the local optical field 30 can be achieved by changing the Fermi level position or the width of the junction channel. For example, a specified gate voltage can be applied to the first photocontainment material 24 or the second photocontainment material 25 to adjust the Fermi level difference, thereby changing the horizontal width w of the depletion junction region, or the channel width h of the depletion junction region can be changed by adjusting the channel width of the photocontainment material.

[0045] In one embodiment, a specified gate voltage is applied to either the first photocontainment material 24 or the second photocontainment material 25. This specified gate voltage adjusts the Fermi level difference between the first and second photocontainment materials 24 and 25, thereby adjusting the horizontal width w of the depletion junction region. Since the formation of the depletion junction region is due to the Fermi level difference between the different confinement materials, changes in this difference directly affect the width of the depletion junction region. A larger Fermi level difference results in a wider depletion junction region, while a smaller difference results in a narrower one. The horizontal width w of the depletion junction region is dynamically adjusted by changing the Fermi levels of the different photocontainment materials through the application of a gate voltage. A positive gate voltage shifts the Fermi level upwards, while a negative gate voltage shifts it downwards. Furthermore, a wider depletion junction region is typically accompanied by a stronger built-in electric field, which helps to more effectively separate photogenerated carriers.

[0046] In one embodiment, the channel widths of the first photocontainment material 24 and the second photocontainment material 25 are adjusted to change the channel width h of the depletion junction region. In semiconductor devices, the channel width h of the depletion junction region directly affects the distribution and intensity of the built-in electric field. A wider depletion junction region generally means a stronger built-in electric field, which helps to more effectively separate photogenerated carriers. Specifically, the physical dimensions of the first photocontainment material 24 and the second photocontainment material 25 can be changed through methods such as material stripping and transfer, chemical etching, and physical deposition, thereby changing the channel width h of the depletion junction region. By adjusting the channel width h of the first and second photocontainment materials, the channel width h of the depletion junction region can be changed, thereby optimizing the distribution of the built-in electric field and the separation efficiency of photogenerated carriers.

[0047] The technical solutions provided in this application, through multiple embodiments, can modify the channel widths of the first and second photoelectric confinement materials to adjust the channel width of the depletion junction region. This allows the entire photoelectric confinement material to be almost entirely covered by the depletion junction region under reverse bias, resulting in extremely low dark current. Furthermore, once thermally excited carriers are generated in this region, they are immediately and rapidly swept towards the electrodes at both ends by the built-in electric field of the depletion junction region, significantly reducing their diffusion and residence time in the material and directly lowering the probability of dark current generation through recombination. By designing an extremely narrow channel photoelectric confinement structure and coordinating depletion region control with the local optical field, the detector's dependence on stringent cooling conditions is effectively reduced, improving the response performance of the photodetector.

[0048] The technical solutions provided in this application, through multiple embodiments, achieve the generation and separation of photogenerated carriers through a precise spatial stacking design of the localized optical field of the plasmonic mode excited by the metal grating structure and the built-in electric field of the depletion junction region. Specifically, the infrared photon energy is directly localized within the depletion region, allowing photogenerated carriers to be generated directly within the depletion junction region. Once generated, these carriers are immediately subjected to a strong built-in electric field, enabling them to be rapidly separated and transported to the electrodes via drift without undergoing a slow diffusion process. This significantly improves the carrier separation efficiency and collection speed, thus enabling the detector to simultaneously possess the advantages of high quantum efficiency and high response speed.

[0049] The further functional descriptions of the above embodiments are the same as those of the corresponding device embodiments described above. For ease of description, the above devices are described separately by function as various units. Of course, in implementing this application, the functions of each unit can be implemented in one or more software and / or hardware.

[0050] Those skilled in the art will understand that embodiments of this application can be provided as methods and apparatus. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product embodied on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0051] This application is described with reference to flowchart illustrations and / or block diagrams of methods and apparatus according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0052] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0053] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0054] It should also be noted that 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 limitation, 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.

[0055] The various embodiments in this specification are described in a progressive manner. Similar or identical parts between embodiments can be referred to interchangeably. Each embodiment focuses on its differences from other embodiments. In particular, the method embodiments are largely similar to the apparatus embodiments, so the description is relatively simple; relevant parts can be referred to the descriptions of the apparatus embodiments.

[0056] The above description is merely an embodiment of this application and is not intended to limit the scope of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of the claims of this application.

[0057] Although embodiments of this application have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of this application, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. A photodetector based on a grating structure, characterized in that, The photodetector includes a substrate layer and a photoelectric material layer. The photoelectric material layer includes a metal grating structure, a first electrode, a second electrode, a first photoelectric confinement material, and a second photoelectric confinement material. The metal grating structure includes a first metal grating and a second metal grating, wherein: The first photoelectric confinement material and the second photoelectric confinement material are in contact, wherein the first photoelectric confinement material and the second photoelectric confinement material form a depletion junction region at the interface; The first metal grating and the second metal grating are symmetrically disposed on both sides of the depletion junction region. The metal grating structure is used to excite plasmon modes with infrared light of a specific wavelength to form a local optical field based on the plasmon modes. The first electrode is connected to the first photoconductive material, and the second electrode is connected to the second photoconductive material. The first electrode and the second electrode are used to extract photogenerated carriers.

2. The photodetector according to claim 1, characterized in that, The local optical field overlaps with the depleted junction region.

3. The photodetector according to claim 1, characterized in that, A built-in electric field is distributed within the depleted junction region, and the width of the built-in electric field matches the local optical field.

4. The photodetector according to claim 3, characterized in that, The depleted junction is used to generate the photogenerated carriers under the influence of the local optical field.

5. The photodetector according to claim 3, characterized in that, The depleted junction is also used to separate the photogenerated carriers into electrons and holes under the action of the built-in electric field.

6. The photodetector according to claim 1, characterized in that, The first photoelectric confinement material is doped with P-type, and the second photoelectric confinement material is doped with N-type.

7. The photodetector according to claim 1 or 5, characterized in that, The doping concentration of both the first and second photoelectric confinement materials is 1×10⁻⁶. 16 cm -3 .

8. The photodetector according to claim 1, characterized in that, The photodetector operates at a temperature of 150K.

9. A photoelectric detection method based on a grating structure, characterized in that, The method uses the photodetector as described in any one of claims 1 to 8, and the method includes: The plasmonic modes of the metal grating structure are excited, and the light field energy is constrained to a specific location based on the transmission characteristics of the plasmonic modes, so as to form a local light field at the specific location. Adjust the horizontal width and channel width of the depletion junction region so that the depletion junction region spatially overlaps with the local optical field; The depletion junction region receives optical energy to generate photogenerated carriers, which are then separated into electrons and holes under the influence of a built-in electric field. Holes are extracted through the first electrode and electrons are extracted through the second electrode to form a photoelectric response signal in the external circuit connected by the first and second electrodes.

10. The method according to claim 9, characterized in that, Adjusting the horizontal width of the depleted junction region and the channel width includes: A specified gate voltage is applied to the first photocontainment material or the second photocontainment material, and the Fermi level difference between the first photocontainment material and the second photocontainment material is adjusted by the specified gate voltage to adjust the horizontal width of the depletion junction region; Adjust the channel widths of the first and second photoelectric confinement materials to change the channel width of the depletion junction region.

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