Plasma resonance enhanced microstructure of infrared photoelectric detector and preparation method

Abstract

The invention provides a plasma resonance enhanced microstructure of an infrared photoelectric detector and a preparation method, and belongs to the technical field of medium-wave infrared photoelectric detectors, and the method comprises the steps: enabling incident light to irradiate downwards from the upper part of a top resonance layer when the medium-wave infrared photoelectric detector is used, and enabling the incident light to irradiate downwards from the lower part of the top resonance layer; the bottom resonance layer, the dielectric blocks and the top resonance layer form an array-arranged microstructure which can excite a plasmon mode, a surface plasmon resonance effect is triggered near the surface of the photosensitive layer through the combined action of the top resonance layer and the bottom resonance layer, the dielectric blocks are embedded in the bottom resonance layer, and the surface plasmon resonance effect is achieved. Incident light is localized in a shallower depth in a photosensitive surface, the intensity of a local electric field is enhanced, the reflection phenomenon of the photosensitive surface is reduced, the light absorption rate of the detector is improved, and the quantum efficiency of the medium-wave infrared photoelectric detector is further improved.

Description

Technical Field

[0001] This application belongs to the technical field of mid-wave infrared photodetectors, and specifically relates to a plasma resonance enhanced microstructure and a preparation method of an infrared photodetector. Background Art

[0002] Mid-wave infrared photodetectors have a wide range of applications in military, industrial, and civilian fields. Due to problems such as high reflectivity on the surface of the photosensitive surface and low absorption efficiency of infrared light by the material, the quantum efficiency of mid-wave infrared photodetectors is affected. Currently, there are artificial microstructures for mid-wave infrared photodetectors, but these microstructures generally have problems of low optical localization efficiency and more energy loss, and the enhancement effect on the quantum efficiency of mid-wave infrared photodetectors is not good. Summary of the Invention

[0003] The present invention aims to solve at least one of the technical problems existing in the prior art or related technologies.

[0004] To this end, a first aspect of the present invention provides a plasma resonance enhanced microstructure of an infrared photodetector.

[0005] A second aspect of the present invention provides a preparation method of a plasma resonance enhanced microstructure of an infrared photodetector.

[0006] In view of this, according to a first aspect of the embodiments of the present application, a plasma resonance enhanced microstructure of an infrared photodetector is proposed, including: A bottom resonance layer, which is disposed on the photosensitive surface of the infrared photodetector; A dielectric block group, which includes a plurality of dielectric blocks. The first end of the dielectric block is embedded in the bottom resonance layer, and the dielectric blocks are arranged on the bottom resonance layer in a periodic array; A top resonance layer, which is disposed on the end face of the second end of the dielectric block.

[0007] In a feasible implementation manner, the plasma resonance enhanced microstructure of the infrared photodetector further includes: A positioning hole group, which includes a plurality of positioning holes. The positioning holes penetrate through the bottom resonance layer along the thickness direction of the bottom resonance layer, and the positioning holes are arranged on the bottom resonance layer in a periodic array. The first end of the dielectric block is embedded in the positioning holes; Wherein, the dielectric blocks and the positioning holes are in one-to-one correspondence.

[0008] In a feasible implementation manner, the sizes of the cross-sections of each dielectric block are the same, the sizes of the cross-sections of each positioning hole are the same, and the size of the cross-section of the dielectric block is the same as the size of the cross-section of the positioning hole; The top resonance layer covers the dielectric block. The dimensions of each cross-section of the top resonance layer are the same, and the dimensions of the cross-section of the top resonance layer are the same as those of the cross-section of the dielectric block.

[0009] In a feasible implementation, the period of the array of positioning holes is 5 / 6 of the peak detection wavelength of the infrared photodetector; The maximum width of the cross-section of the positioning hole is 1 / 3 to 1 / 2 of the peak detection wavelength of the infrared photodetector.

[0010] In a feasible implementation, the bottom resonance layer is a metal thin film; The thickness of the bottom resonance layer is 20 nm to 40 nm.

[0011] In a feasible implementation, the material of the dielectric block is a semiconductor or a semiconductor oxide; The height of the dielectric block is 300 nm to 400 nm.

[0012] In a feasible implementation, the material of the dielectric block is the same as the material of the photosensitive surface, and the relative deviation of the dielectric constant of the material of the dielectric block from the dielectric constant of the material of the photosensitive surface is not greater than 15%.

[0013] In a feasible implementation, the top resonance layer is a metal thin film; The thickness of the top resonance layer is the same as the thickness of the bottom resonance layer.

[0014] According to the second aspect of the embodiments of the present application, a method for preparing a plasma resonance enhanced microstructure of an infrared photodetector is provided, which is used to prepare the plasma resonance enhanced microstructure of the infrared photodetector according to any of the above technical solutions. The preparation method includes: Deposit the bottom resonance layer on the photosensitive surface of the infrared photodetector; Make a hole pattern arranged in a periodic array on the bottom resonance layer, and etch the bottom resonance layer according to the hole pattern; Deposit the dielectric block and the top resonance layer to obtain a sample; Immerse the sample in an organic solvent, strip the photoresist, and remove the structure whose vertical projection on the bottom resonance layer is outside the hole pattern.

[0015] In a feasible implementation, inductively coupled plasma dry etching is performed on the bottom resonance layer to obtain a bottom resonance layer with positioning holes arranged in a periodic array.

[0016] The plasma resonance enhanced microstructure and preparation method of an infrared photodetector of the present application, compared with the prior art, have the beneficial effects as follows: The plasmon resonance enhanced microstructure of the infrared photodetector provided by the embodiment of the present application includes a bottom resonance layer, a dielectric block group, and a top resonance layer. When using a mid-wave infrared photodetector, incident light irradiates downward from above the top resonance layer. The microstructure formed by the array arrangement of the bottom resonance layer, the dielectric blocks, and the top resonance layer can excite plasmon modes. Through the combined action of the top resonance layer and the bottom resonance layer, a surface plasmon resonance effect is induced near the surface of the photosensitive layer. The dielectric blocks are embedded in the bottom resonance layer to localize the incident light within a relatively shallow depth in the photosensitive surface, enhance the local electric field intensity, reduce the reflection phenomenon of the photosensitive surface, improve the light absorption rate of the detector, and thus improve the quantum efficiency of the mid-wave infrared photodetector; the top resonance layer and the bottom resonance layer form a vertical resonant cavity through the intermediate dielectric blocks. The incident light is reflected multiple times between the top resonance layer and the bottom resonance layer to form a standing wave pattern, further compressing the light field to the shallow region of the photosensitive surface, enhancing the energy localization through resonant feedback, reducing the reflection loss of light on the surface of the photosensitive surface, and improving the photoelectric conversion efficiency. Description of the Drawings

[0017] By reading the following detailed description of the preferred embodiments, various other advantages and benefits will become clear to those of ordinary skill in the art. The drawings are only for the purpose of illustrating the preferred embodiments and are not considered to be a limitation of the present application. Moreover, throughout the drawings, the same reference numerals are used to represent the same components. In the drawings: Figure 1 It is the first schematic three-dimensional structure diagram of the plasmon resonance enhanced microstructure of the infrared photodetector provided by an embodiment of the present application; Figure 2 It is the first schematic sectional view of the plasmon resonance enhanced microstructure of the infrared photodetector provided by an embodiment of the present application; Figure 3 It is the first schematic top view of the plasmon resonance enhanced microstructure of the infrared photodetector provided by an embodiment of the present application; Figure 4 It is the second schematic structure diagram of the plasmon resonance enhanced microstructure of the infrared photodetector provided by an embodiment of the present application; Figure 5 It is the third schematic structure diagram of the plasmon resonance enhanced microstructure of the infrared photodetector provided by an embodiment of the present application; Figure 6 It is the schematic step flow chart of the preparation method of the plasmon resonance enhanced microstructure of the infrared photodetector provided by an embodiment of the present application; Figure 7 It is the two-dimensional photocurrent density diagram of the mid-wave infrared photodetector; Figure 8The two-dimensional photocurrent density map after integrating the micro-structure for the mid-wave infrared photodetector; Figure 9 The zero-bias detectivity curve graphs at room temperature before and after integrating the micro-structure on the mid-wave infrared photodetector; Among them, Figures 1 to 5 The corresponding relationship between the reference numerals and the component names in 1. Bottom resonance layer; 2. Dielectric block; 3. Top resonance layer; 4. Photosensitive surface; 5. Positioning hole. Specific embodiments

[0018] In the description of the present application, it should be understood that the orientation or positional relationships indicated by the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc. are based on the orientation or positional relationships shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present application.

[0019] In addition, the terms "first" and "second" are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present application, "a plurality of" means two or more, unless otherwise specifically defined.

[0020] In the present application, unless otherwise clearly defined and limited, the terms "installed", "connected", "connected", "fixed", etc. should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection; it may be a mechanical connection or an electrical connection; it may be directly connected, or indirectly connected through an intermediate medium, and it may be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to specific circumstances.

[0021] The following describes the preferred embodiments of the present application with reference to the drawings. It should be understood that the preferred embodiments described herein are only for the purpose of illustrating and explaining the present application, and are not used to limit the present application.

[0022] Such as Figures 1 to 3As shown in the figure, according to the first aspect of the embodiments of the present application, a plasma resonance enhanced microstructure of an infrared photodetector is proposed, which includes: a bottom resonance layer 1, a dielectric block group, and a top resonance layer 3; the bottom resonance layer 1 is disposed above the photosensitive surface 4 of the infrared photodetector; the dielectric block group includes a plurality of dielectric blocks 2, the first end of the dielectric block 2 is embedded in the bottom resonance layer 1, and the dielectric blocks 2 are arranged on the bottom resonance layer 1 in a periodic array; the top resonance layer 3 is disposed above the end face of the second end of the dielectric block 2.

[0023] The plasma resonance enhanced microstructure of the infrared photodetector provided by the embodiments of the present application includes a bottom resonance layer 1, a dielectric block group, and a top resonance layer 3. When using a mid-wave infrared photodetector, the incident light irradiates downward from above the top resonance layer 3. The microstructure formed by the array arrangement of the bottom resonance layer 1, the dielectric block 2, and the top resonance layer 3 can excite the surface plasmon mode. Through the combined action of the top resonance layer 3 and the bottom resonance layer 1, a surface plasmon resonance effect is induced near the surface of the photosensitive layer. The dielectric block 2 is embedded in the bottom resonance layer 1 to localize the incident light within a relatively shallow depth in the photosensitive surface 4, enhance the local electric field strength, reduce the reflection phenomenon of the photosensitive surface 4, improve the light absorption rate of the detector, and thus improve the quantum efficiency of the mid-wave infrared photodetector; the top resonance layer 3 and the bottom resonance layer 1 form a vertical resonator through the intermediate dielectric block 2. The incident light is reflected multiple times between the top resonance layer 3 and the bottom resonance layer 1 to form a standing wave mode, further compressing the light field to the shallow region of the photosensitive surface 4, enhancing the energy localization through resonance feedback, reducing the reflection loss of light on the surface of the photosensitive surface 4, and improving the photoelectric conversion efficiency.

[0024] It should be noted that the periodic array refers to a regular structure formed by multiple structural units repeating in a two-dimensional or three-dimensional space according to a fixed period (interval).

[0025] As a preferred solution, the infrared photodetector is a mid-wave infrared photodetector.

[0026] As Figure 2 As shown in the figure, in a feasible implementation manner, the plasma resonance enhanced microstructure of the infrared photodetector further includes: a positioning hole group, the positioning hole group includes a plurality of positioning holes 5, the positioning holes 5 penetrate through the bottom resonance layer 1 along the thickness direction of the bottom resonance layer 1, the positioning holes 5 are arranged on the bottom resonance layer 1 in a periodic array, and the first end of the dielectric block 2 is embedded in the positioning holes 5; wherein, the dielectric block 2 and the positioning holes 5 are in one-to-one correspondence.

[0027] In this technical solution, the dielectric block 2 is embedded in the corresponding positioning hole 5 to ensure the accuracy of the period of the dielectric block 2 array, thereby improving the position accuracy of the top resonance layer in the horizontal direction, avoiding a large difference between the period of the actually fabricated microstructure and the designed microstructure period, preventing the surface plasmon resonance mode from changing, and avoiding resonance shift caused by structural deviation between the bottom resonance layer 1 and the corresponding top resonance layer 3, improving the stability of the plasmon resonance, thereby improving the compression effect on the optical field, localizing the optical field in the shallow region of the photosensitive surface 4, and ensuring the enhancement effect of the microstructure on the detector quantum efficiency.

[0028] As Figure 2 shown, in a feasible implementation, the sizes of the cross-sections of each dielectric block 2 are the same, the sizes of the cross-sections of each positioning hole 5 are the same, and the size of the cross-section of the dielectric block 2 is the same as the size of the cross-section of the positioning hole 5; the top resonance layer 3 covers the dielectric block 2, the sizes of the cross-sections of the top resonance layer 3 are the same, and the size of the cross-section of the top resonance layer 3 is the same as the size of the cross-section of the dielectric block 2.

[0029] In this technical solution, the dielectric block 2 and the positioning hole 5 have the same cross-sectional size, so that the propagation phases of the optical field in the positioning holes 5 arranged in a periodic array form are consistent. By eliminating the scattering loss caused by size mutation, the surface plasmon wave vector is matched with the dielectric waveguide mode, enhancing the effect of the optical field localization effect; the top resonance layer 3 and the dielectric block 2 have the same cross-sectional size, forming a closed resonator, making the incident light reflect multiple times in the vertical direction, and compressing the optical field to the shallow layer of the photosensitive surface 4 through the standing wave effect, improving the light absorption efficiency.

[0030] In this technical solution, the positioning hole 5 and the dielectric block 2 have the same cross-sectional size, serving as the alignment reference for the lithography process, precisely controlling the cross-sectional size of the dielectric block 2, avoiding an increase in error after stacking the top resonance layer 3, and thus avoiding the shift of the plasma resonance peak. In the stripping process of the dielectric block 2 and the top resonance layer 3, keeping the cross-sectional sizes of the dielectric block 2 and the top resonance layer 3 consistent can reduce the erosion of the microstructural sidewalls by organic solvents, ensuring the smoothness and cleanliness of the microstructural sidewalls, and thus ensuring the period accuracy of the microstructure.

[0031] Furthermore, the dielectric block 2 is a columnar body. In some examples, such as Figure 1 、 Figure 4 and Figure 5 , the cross-section of the dielectric block 2 can be a square, a circle or a rectangle, that is, the dielectric block 2 can be a cuboid, and the dielectric block 2 can also be a cylinder.

[0032] In a feasible implementation, the period of the array of positioning holes 5 is 5 / 6 of the peak detection wavelength of the mid-wave infrared photodetector; the maximum width of the cross-section of the positioning hole 5 is 1 / 3 to 1 / 2 of the peak detection wavelength of the mid-wave infrared photodetector.

[0033] In this technical solution, the period of the array of positioning holes 5 is set to 5 / 6 of the peak detection wavelength to ensure that the arrangement of the positioning holes 5 satisfies the surface wave phase matching condition and forms a standing wave resonance; at the same time, the structure of the positioning holes 5 arranged in a periodic array form will form a photonic crystal bandgap, suppressing the propagation of non-target wavelengths and avoiding the bandgap shifting to the long-wave region due to too large period parameters of the positioning holes 5, thereby preventing the reduction of the local efficiency of mid-wave infrared. By setting the maximum width of the cross-section of the positioning hole 5 to 1 / 3 to 1 / 2 of the peak detection wavelength of the mid-wave infrared photodetector, it is ensured that the resonance mode covers the mid-wave infrared band, and the size of the positioning hole 5 is close to the sub-wavelength scale. Through Mie resonance and diffraction effects, the incident light is scattered to the shallow area below the photosensitive surface 4, increasing the optical path and reducing the reflection loss; at the same time, the ratio of the size of the positioning hole 5 to the wavelength determines the frequency range of the resonance mode. By making the maximum width of the cross-section of the positioning hole 5 1 / 3 to 1 / 2 of the peak detection wavelength of the mid-wave infrared photodetector, it is avoided that it is difficult to excite high-order modes due to too small size and multi-mode coupling noise caused by too large size, which is beneficial to improving the photoelectric conversion efficiency and effect.

[0034] In a feasible implementation, the bottom resonance layer 1 is a metal thin film; the thickness of the bottom resonance layer 1 is 20 nm to 40 nm.

[0035] In this technical solution, the coupling of the incident light with the free electrons in the metal thin film excites the surface plasmon resonance, localizing the optical field within the sub-wavelength scale of the shallow layer of the photosensitive surface 4 and significantly enhancing the local electric field intensity; the thickness of the bottom resonance layer 1 is set to 20 nm to 40 nm so that the thickness of the bottom resonance layer 1 matches the penetration depth of the surface plasmon, avoiding discontinuity and non-uniformity due to too thin thickness of the bottom resonance layer 1, resulting in increased loss; at the same time, avoiding the bottom resonance layer 1 being too thick causing optical absorption saturation and reducing the resonance quality factor; the metal thin film also undertakes the function of heat conduction, and the thickness of the metal thin film of this size is appropriate, which can reduce the heat capacity on the basis of maintaining low radiative thermal conductance and avoid the sudden increase of dark current at high temperatures.

[0036] In some examples, the metal in the metal thin film of the bottom resonance layer 1 can be gold (Au), silver (Ag) or aluminum (Al).

[0037] In a feasible implementation, the material of the dielectric block 2 is a semiconductor or a semiconductor oxide; the height of the dielectric block 2 is 300 nm to 400 nm.

[0038] In this technical solution, the height of the dielectric block 2 is designed to be 300 nm to 400 nm, so that the height of the dielectric block 2 matches the numerical value of the surface plasmon resonance penetration depth, making the light field mainly localize on the surface layer of the photosensitive surface 4. By optimizing the thickness of the dielectric block 2, the maximization of the interaction between the light field and the material is achieved.

[0039] In some examples, the semiconductor material can be silicon (Si), germanium (Ge), or indium arsenide (InAs); the semiconductor oxide material can be titanium oxide, zinc oxide, tungsten oxide, tin oxide, indium oxide, or tantalum pentoxide.

[0040] In a feasible implementation, the material of the dielectric block 2 is the same as that of the photosensitive surface 4, and the relative deviation of the dielectric constant of the material of the dielectric block 2 from the dielectric constant of the material of the photosensitive surface 4 is not greater than 15%.

[0041] In this technical solution, the relative deviation of the dielectric constant of the material of the dielectric block 2 from the dielectric constant of the material of the photosensitive surface 4 is set within 15%, so that the Fresnel reflection coefficient of the incident light at the interface between the photosensitive surface 4 and the dielectric block 2 is reduced to less than 0.5%; at the same time, the wave vector matching condition of the surface plasmon is easier to meet, the offset of the surface plasmon resonance wavelength can be accurately controlled, ensuring effective coverage in the 3 μm to 5 μm mid-wave infrared band, and optimizing the light field coupling efficiency; the dielectric block 2 and the photosensitive surface 4 are made of the same material, which can achieve stress matching between the dielectric block 2 and the photosensitive surface 4, avoid cracking of the metal thin film, and extend the service life of the microstructure.

[0042] In a feasible implementation, the top resonance layer 3 is a metal thin film; the thickness of the top resonance layer 3 is the same as that of the bottom resonance layer 1.

[0043] In this technical solution, the top resonance layer 3 and the bottom resonance layer 1 have the same thickness, so that the resonance frequencies of the top resonance layer 3 and the bottom resonance layer 1 are matched, optimizing the resonance efficiency. The natural frequencies of the top resonance layer 3 and the bottom resonance layer 1 converge, avoiding mechanical fatigue caused by the superposition of multi-frequency resonances, reducing the local amplitude, and extending the service life of the microstructure; at the same time, the same thickness of the top resonance layer 3 and the bottom resonance layer 1 can also reduce interface reflection and enhance the light field coupling efficiency.

[0044] In some examples, the metal in the metal thin film of the top resonance layer 3 can be gold (Au), silver (Ag), or aluminum (Al).

[0045] As Figure 6 shown, according to the second aspect of the present application, a preparation method for a plasma resonance enhanced microstructure of an infrared photodetector is proposed, which is used to prepare the plasma resonance enhanced microstructure of the infrared photodetector according to any one of the above technical solutions, including: Step 100: Deposit the bottom resonance layer 1 on the photosensitive surface 4 of the mid-wave infrared photodetector; Step 200: Fabricate a hole pattern arranged in a periodic array form on the bottom resonance layer 1, and etch the bottom resonance layer 1 according to the hole pattern; Step 300: Deposit the dielectric block 2 and the top resonance layer 3 to obtain a sample; Step 400: Immerse the sample in an organic solvent to strip the photoresist and remove the structures whose vertical projections on the bottom resonance layer 1 are located outside the hole pattern.

[0046] Through the preparation method of the plasmon resonance enhanced microstructure of the infrared photodetector provided by the embodiments of the present application, by scribing a hole pattern arranged in a periodic array form on the bottom resonance layer 1 and etching the bottom resonance layer 1 according to the hole pattern, the micron-level positioning of the dielectric block 2 can be realized, and the precision of the microstructure after depositing the dielectric block 2 and the top resonance layer 3 can be improved; the photoresist is stripped in an organic solvent, and the redundant structures on the dielectric block 2 and the bottom resonance layer 1 are removed, avoiding the tearing of the microstructure and stripping the microstructure without damage, further ensuring the precision after the preparation of the microstructure; when using the mid-wave infrared photodetector, the incident light irradiates downward from the upper direction of the top resonance layer 3, and the microstructure formed by the periodic arrangement of the bottom resonance layer 1, the dielectric block 2 and the top resonance layer 3 can excite the plasmon mode. Through the combined action of the top resonance layer 3 and the bottom resonance layer 1, the surface plasmon resonance effect is triggered near the surface of the photosensitive layer. The dielectric block 2 is embedded in the bottom resonance layer 1 to localize the incident light within a relatively shallow depth in the photosensitive surface 4, enhance the local electric field intensity, reduce the reflection phenomenon of the photosensitive surface 4, improve the light absorption rate of the detector, and thus improve the quantum efficiency of the mid-wave infrared photodetector; the top resonance layer 3 and the bottom resonance layer 1 form a vertical resonator through the intermediate dielectric block 2. The incident light is reflected multiple times between the top resonance layer 3 and the bottom resonance layer 1 to form a standing wave mode, further compressing the light field to the shallow layer region of the photosensitive surface 4, enhancing the energy locality through resonance feedback, reducing the reflection loss of light on the surface of the photosensitive surface 4, and improving the photoelectric conversion efficiency.

[0047] Furthermore, the deposition of the bottom resonance layer 1 is carried out in a high-vacuum environment with a deposition rate of 2 nm / min to 5 nm / min; the deposition of the dielectric block 2 is carried out in a high-vacuum environment with a deposition rate of 20 nm / min to 100 nm / min; the deposition of the top resonance layer 3 is carried out in a high-vacuum environment with a deposition rate of 2 nm / min to 5 nm / min. This is to reduce residual gas molecules such as oxygen and water vapor, avoid chemical reactions between each layer of material and the gas during deposition, and thus ensure the chemical purity of the overall microstructure; by depositing the bottom resonance layer 1 and the top resonance layer 3 at a lower deposition rate, the atomic-level precision of the bottom resonance layer 1 and the top resonance layer 3 can be ensured, the internal stress accumulation in the bottom resonance layer 1 and the top resonance layer 3 can be reduced, the occurrence of lattice distortion or interface defects can be avoided, and at the same time, it is convenient to precisely control the coating thickness to improve the preparation precision of the overall microstructure.

[0048] In some examples, the material of the dielectric block 2 can be single crystal, polycrystal or amorphous material.

[0049] In some examples, the bottom resonance layer 1 can be deposited on the photosensitive surface 4 by thermal evaporation process, electron beam evaporation process or magnetron sputtering process.

[0050] In some examples, a mask plate lithography process, a laser direct writing process or an electron beam lithography process can be used to form a periodically arrayed hole pattern on the bottom resonance layer 1.

[0051] In some examples, the dielectric block 2 and the top resonance layer 3 can be deposited on the photosensitive surface 4 by thermal evaporation process, electron beam evaporation process or magnetron sputtering process.

[0052] In some examples, the organic solvent can be acetone or N-methylpyrrolidone.

[0053] In a feasible implementation, inductively coupled plasma dry etching is performed on the bottom resonance layer 1 to obtain the bottom resonance layer 1 with positioning holes 5 arranged in a periodically arrayed form.

[0054] In this technical solution, inductively coupled plasma dry etching can independently control the ion concentration (radio frequency coil power) and the bombardment energy (bias power). The ion concentration and energy can be independently controlled, which helps to improve the etching precision and efficiency. The perpendicularity of the sidewall of the positioning hole 5 reaches 88° ± 1°, reducing the perpendicularity error of the sidewall of the positioning hole 5. At the same time, it can reduce the size deviation of the positioning hole 5, improve the precision of the period of the positioning hole 5, meet the requirement of consistency for the periodic holes, and meet the resonance matching requirement of the positioning hole 5; inductively coupled plasma dry etching is carried out at low temperature, which can avoid thermal stress distortion of the bottom resonance layer 1 caused by high temperature, prevent cracking of the edge of the periodic holes, ensure the smoothness of the sidewall of the positioning hole 5, and thus achieve precise control of the period of the positioning hole 5 array.

[0055] The preparation method of the plasma resonance enhanced microstructure of the infrared photodetector provided by the embodiments of the present application is applied to the plasma resonance enhanced microstructure of the infrared photodetector in any of the above technical solutions. Therefore, the preparation method of the plasma resonance enhanced microstructure of the infrared photodetector has all the beneficial effects of the plasma resonance enhanced microstructure of the infrared photodetector in the above technical solutions, which will not be elaborated here.

[0056] Example 1: This embodiment provides an artificial microstructure for enhancing the light utilization efficiency of a mid-wave infrared photodetector. As Figure 1 shown, it includes a bottom resonance layer 1, a dielectric block 2, and a top resonance layer 3. The bottom resonance layer 1 has a thickness of 20 nm and is made of Au. There is a positioning hole 5 structure arranged in a periodic array on the bottom resonance layer 1. The shape of the positioning hole 5 is square, the side length of the square is 1.25 μm, and the period of the square positioning hole 5 array is 2.75 μm. The dielectric block 2 has a height of 300 nm and is made of Si. The top resonance layer 3 has a thickness of 20 nm and is made of Au. When in use, incident light irradiates downward from above the top resonance layer 3. Through the combined action of the top resonance layer 3 and the bottom resonance layer 1, it is localized in a shallower area below the bottom resonance layer 1 and is finally absorbed by the infrared photodetector and converted into a current signal for output.

[0057] When preparing the microstructure, first, Au is deposited on the photosensitive surface 4 of the mid-wave infrared photodetector by thermal evaporation at a deposition rate of 2 nm / min to form the bottom resonance layer 1 with a metal thin film structure; then, a square hole pattern arranged in a periodic array is etched on the bottom resonance layer 1 by mask plate lithography; then, the bottom resonance layer 1 is dry-etched by inductively coupled plasma etching process to obtain the bottom resonance layer 1 with square positioning holes 5 arranged in a periodic array; then, Si dielectric blocks are deposited on the bottom resonance layer 1 by thermal evaporation at a deposition rate of 20 nm / min and Au thin films are deposited at a deposition rate of 2 nm / min to form the dielectric block 2 and the top resonance layer 3, obtaining a sample; finally, the sample is soaked in acetone, and the excess photoresist, Si dielectric, and Au thin film on the sample surface are stripped off to complete the preparation of the microstructure with a square cross-section.

[0058] Example 2: This embodiment provides an artificial microstructure for enhancing the light utilization efficiency of a mid-wave infrared photodetector. As Figure 4As shown, it includes a bottom resonance layer 1, a dielectric block 2, and a top resonance layer 3. The bottom resonance layer 1 has a thickness of 30 nm and is made of Ag. There is a positioning hole 5 structure arranged in the form of a periodic array on the bottom resonance layer 1. The shape of the positioning hole 5 is circular, the diameter of the circle is 1.5 μm, and the period of the circular positioning hole 5 array is 2.5 μm. The dielectric block 2 has a height of 350 nm and is made of Ge. The top resonance layer 3 has a thickness of 30 nm and is made of Ag. When in use, the incident light irradiates downward from above the top resonance layer 3. Through the combined action of the top resonance layer 3 and the bottom resonance layer 1, it is localized in a shallower area below the bottom resonance layer 1 and is finally absorbed by the infrared photodetector and converted into a current signal for output.

[0059] When preparing the microstructure, first, Ag is deposited on the photosensitive surface 4 of the mid-wave infrared photodetector by electron beam evaporation at a deposition rate of 3 nm / min to form the bottom resonance layer 1 with a metal thin film structure; then, a circular hole pattern arranged in the form of a periodic array is engraved on the bottom resonance layer 1 by laser direct writing; then, the bottom resonance layer 1 is dry-etched by inductively coupled plasma etching to obtain the bottom resonance layer 1 with circular positioning holes 5 arranged in the form of a periodic array; then, a Ge dielectric block is deposited on the bottom resonance layer 1 by electron beam evaporation at a deposition rate of 50 nm / min and an Ag thin film is deposited at a deposition rate of 3 nm / min to form the dielectric block 2 and the top resonance layer 3, obtaining a sample; finally, the sample is soaked in acetone, and the excess photoresist, Ge dielectric, and Ag thin film on the sample surface are peeled off to complete the preparation of the microstructure with a square cross-section.

[0060] Example 3: This example provides an artificial microstructure for enhancing the light utilization efficiency of a mid-wave infrared photodetector, as Figure 5 shown, it includes a bottom resonance layer 1, a dielectric block 2, and a top resonance layer 3. The bottom resonance layer 1 has a thickness of 40 nm and is made of Al. There is a positioning hole 5 structure arranged in the form of a periodic array on the bottom resonance layer 1. The shape of the positioning hole 5 is rectangular, the length of the rectangle is 1.5 μm, the width is 1.25 μm, and the period of the rectangular positioning hole 5 array is 2.75 μm. The dielectric block 2 has a height of 400 nm and is made of InAs. The top resonance layer 3 has a thickness of 40 nm and is made of Al. When in use, the incident light irradiates downward from above the top resonance layer 3. Through the combined action of the top resonance layer 3 and the bottom resonance layer 1, it is localized in a shallower area below the bottom resonance layer 1 and is finally absorbed by the infrared photodetector and converted into a current signal for output.

[0061] When preparing the micro-structure, first, Al is deposited on the photosensitive surface 4 of the mid-wave infrared photodetector by magnetron sputtering at a deposition rate of 5 nm / min to form the bottom resonance layer 1 of the metal thin film structure; then, a rectangular hole pattern arranged in a periodic array form is etched on the bottom resonance layer 1 by mask plate lithography; then, the bottom resonance layer 1 is dry-etched by inductively coupled plasma etching to obtain the bottom resonance layer 1 with rectangular positioning holes 5 arranged in a periodic array form; then, InAs dielectric blocks are deposited on the bottom resonance layer 1 by thermal evaporation at a deposition rate of 100 nm / min and an Al thin film is deposited at a deposition rate of 5 nm / min to form the dielectric blocks 2 and the top resonance layer 3, obtaining a sample; finally, the sample is soaked in acetone, and the redundant photoresist, InAs dielectric and Au thin film on the sample surface are peeled off to complete the preparation of the micro-structure with a rectangular cross-section.

[0062] Integrate the micro-structure prepared in Example 2 on the mid-wave infrared photodetector, as Figure 4 shown.

[0063] Figure 7 shows the generation rate of photo-generated carriers inside the device when the micro-structure is not integrated on the mid-wave infrared photodetector, Figure 8 shows the generation rate of photo-generated carriers inside the device after integrating the micro-structure in Example 2 on the mid-wave infrared photodetector; by comparing Figure 7 and Figure 8 the generation rates of photo-generated carriers inside the two devices, it can be analyzed that, compared with the device without the integrated micro-structure, the generation rate of photo-generated carriers in the absorption layer of the device with the integrated micro-structure is significantly improved, and the position with the highest improvement amplitude is within a relatively shallow range directly below the micro-structure; it can be proved that the micro-structure excites local surface plasmon resonance on the surface of the mid-wave infrared photodetector device, thereby improving the utilization rate of incident light by the mid-wave infrared photodetector. Figure 9 The black curve in shows the variation of the photocurrent response with wavelength in the mid-wave infrared photodetector device, Figure 9 the red curve in shows the variation of the photocurrent of the device after integrating the micro-structure with wavelength, and through Figure 9 it can be seen that integrating the micro-structure on the mid-wave infrared photodetector has a significant effect on improving the photocurrent of the device and increases the optical responsivity of the device.

[0064] It can be understood that in the same kind of infrared photodetector, the generation rate of photo-generated carriers is in a strict proportional relationship with the photocurrent. Therefore, through Figure 7 and Figure 8 the generation rates of photo-generated carriers of the devices shown, the photocurrent density inside the device can be intuitively judged.

[0065] Those skilled in the art can easily understand that, on the premise of no conflict, the above-mentioned embodiments can be freely combined and superimposed.

[0066] The above are only the preferred embodiments of the present application and are not intended to limit the present application. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present application shall be included within the protection scope of the present application. The above is only the preferred implementation manner of the present application. It should be noted that for those of ordinary skill in the art in this technical field, several improvements and modifications can be made without departing from the technical principle of the present application, and these improvements and modifications should also be regarded as within the protection scope of the present application.

Claims

1. A plasma resonance enhanced microstructure of an infrared optoelectronic detector, characterized in that The plasma resonance enhancement microstructure of the infrared photodetector includes: A bottom resonance layer disposed on the photosensitive surface of the infrared photodetector; A dielectric block group including a plurality of dielectric blocks. The first end of each dielectric block is embedded in the bottom resonance layer, and the dielectric blocks are arranged on the bottom resonance layer in a periodic array; A top resonance layer disposed on the end face of the second end of the dielectric block.

2. The plasma resonance enhanced microstructure of an infrared optoelectronic detector according to claim 1, wherein The plasma resonance enhancement microstructure of the infrared photodetector further includes: A positioning hole group including a plurality of positioning holes. The positioning holes penetrate through the bottom resonance layer along the thickness direction of the bottom resonance layer, and the positioning holes are arranged on the bottom resonance layer in a periodic array. The first end of the dielectric block is embedded in the positioning holes; Wherein, the dielectric blocks and the positioning holes are in one-to-one correspondence.

3. The plasma resonance enhancement microstructure of an infrared photodetector according to claim 2, characterized in that The sizes of the cross-sections of each dielectric block are the same, the sizes of the cross-sections of each positioning hole are the same, and the size of the cross-section of the dielectric block is the same as the size of the cross-section of the positioning hole; The top resonance layer covers the dielectric block, the sizes of the cross-sections of the top resonance layer are the same, and the size of the cross-section of the top resonance layer is the same as the size of the cross-section of the dielectric block.

4. The plasma resonance enhancement microstructure of an infrared photodetector according to claim 2, characterized in that The period of the array of the positioning holes is 5 / 6 of the peak detection wavelength of the infrared photodetector; The maximum width of the cross-section of the positioning hole is 1 / 3 - 1 / 2 of the peak detection wavelength of the infrared photodetector.

5. The plasma resonance enhancement microstructure of an infrared photodetector according to claim 1, characterized in that The bottom resonance layer is a metal thin film; The thickness of the bottom resonance layer is 20 nm - 40 nm.

6. The plasma resonance enhancement microstructure of an infrared photodetector according to claim 1, characterized in that The material of the dielectric block is a semiconductor or a semiconductor oxide; The height of the dielectric block is 300 nm - 400 nm.

7. The plasma resonance enhancement microstructure of an infrared photodetector according to claim 6, characterized in that The material of the dielectric block is the same as the material of the photosensitive surface, and the relative deviation of the dielectric constant of the material of the dielectric block from the dielectric constant of the material of the photosensitive surface is not more than 15%.

8. The plasma resonance enhancement microstructure of an infrared photodetector according to claim 5, characterized in that The top resonance layer is a metal thin film; The thickness of the top resonance layer is the same as the thickness of the bottom resonance layer.

9. A preparation method for a plasma resonance enhanced microstructure of an infrared optoelectronic detector, characterized in that, A method for preparing the plasma resonance enhancement microstructure of an infrared photodetector according to any one of claims 1 - 8, the preparation method includes: Depositing a bottom resonance layer on the photosensitive surface of the infrared photodetector; A hole pattern arranged in the form of a periodic array is fabricated on the bottom resonance layer, and the bottom resonance layer is etched according to the hole pattern; A dielectric block and a top resonance layer are deposited to obtain a sample; The sample is immersed in an organic solvent to strip the photoresist and remove the structures whose vertical projections on the bottom resonance layer are located outside the hole pattern.

10. The preparation method of the plasma resonance enhanced microstructure of an infrared photodetector according to claim 9, characterized in that The bottom resonance layer is etched by inductively coupled plasma dry etching to obtain the bottom resonance layer with positioning holes arranged in the form of a periodic array.

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