Lead salt uncooled medium-wave infrared detector with enhanced structure and preparation method of lead salt uncooled medium-wave infrared detector

Abstract

The invention discloses a lead salt uncooled medium wave infrared detector with an enhanced structure and a preparation method thereof, and relates to the technical field of photoelectric detection, and the detector comprises a substrate, a reflecting layer, a dielectric layer, a microstructure array layer, a lead salt sensitive layer, a metal electrode layer and a passivation layer. The preparation method comprises: preparing the metal reflecting layer on the surface of the substrate; preparing a resonant cavity layer on the reflecting layer; preparing a microstructure array layer on the resonant cavity layer; preparing a lead salt sensitive layer on the microstructure array layer; carrying out sensitization treatment on the lead salt sensitive layer; preparing a metal electrode on the lead salt sensitive layer; and preparing a passivation layer on the lead salt sensitive layer and the metal electrode. The invention has the beneficial effects that the combined action of the LSPR effect of the resonant cavity and the artificial plasmon polariton array (namely the metal microstructure array) is combined, and the medium-wave infrared radiation absorption of the device can be effectively enhanced. The method has the characteristics of high performance, high sensitivity, high stability and the like, and is expected to be widely applied to the field of medium-wave infrared detection.

Description

Technical Field

[0001] The present invention relates to the technical field of medium-wave infrared detectors, and in particular to a lead salt non-cooled medium-wave infrared detector based on an artificial plasma exciton array and a preparation method thereof. Background Art

[0002] Mid-infrared (MIR) electromagnetic spectrum plays an important role in applications such as gas sensing, thermal imaging, biosensing, medical imaging, spectroscopy and environmental monitoring. The practical application of these applications depends on high-response photodetectors. Most mid-infrared detectors on the market are mainly based on III-V compound semiconductors or mercury-cadmium-telluride (HgCdTe) alloys, such as InSb, In 1-x Ga x As and Hg 1-x Cd x Te. However, all devices made from this material require refrigeration, which is costly, bulky, and has a complex manufacturing process. As an alternative, lead salt compounds (such as PbS, PbSe, etc.) have been used in mid-infrared photoelectric detection since the 1950s. Due to their excellent mid-infrared response characteristics at room temperature and relatively low cost, they have regained attention in recent years and become the preferred material for uncooled infrared detectors.

[0003] Although lead salt materials have excellent mid-infrared response performance, their light absorption coefficient is relatively low, which leads to lower absorption efficiency in thin film applications. To compensate for this defect, current lead salt material detectors usually rely on larger pixel units to increase the absorption area, thereby improving the overall signal response intensity. However, this method limits the improvement of the detector's resolution, making it difficult to meet the needs of low-cost, high-resolution detection. In order to improve the light absorption efficiency of lead salt films, researchers have proposed a variety of process improvement methods, such as heterojunction structure design and nanostructured processing. The heterojunction structure can effectively improve the carrier separation efficiency by forming a barrier layer or quantum well between the lead salt material and other materials, thereby improving the detector response speed. Nanostructuring utilizes the local field enhancement effect to enhance light absorption on the surface of the lead salt material by etching micro-nanostructures. However, although these methods can improve the detection performance to a certain extent, they also bring about the complexity of the manufacturing process and material compatibility issues, making it difficult to apply to large-scale mass production.

[0004] In recent years, researchers have proposed a design scheme to control the light field through artificial micro-photonic structures (such as photonic crystals, nano-gratings and surface plasmon structures) to address the problems of absorption efficiency and integration in traditional lead salt material detectors. Artificial micro-photonic structures can produce a resonance effect in a specific band, confining the incident light to the surface of the lead salt material, thereby significantly improving the light absorption efficiency. This structural design achieves local field enhancement of mid-infrared light through coupling with lead salt films, providing technical support for the manufacture of small-sized, high-resolution detectors.

[0005] Based on the above background, a new type of lead salt uncooled mid-wave infrared detector structure was developed. By designing a periodic micro-photon metal array structure, the localized enhancement of the light field was achieved. This design not only improves the performance of the detector at room temperature, but also avoids the complexity and high cost of the traditional gain structure. After searching, there are very few cases of similar lead salt mid-wave infrared detector structure design and actual application in domestic and foreign public literature. Summary of the invention

[0006] The purpose of the present invention is to solve at least one of the technical problems existing in the prior art and to provide a lead salt uncooled medium-wave infrared detector based on an artificial plasma exciton array and a preparation method thereof.

[0007] The technical solution of the present invention is as follows:

[0008] The first aspect of the present invention provides a lead salt uncooled medium-wave infrared detector with an enhanced structure, wherein the detector comprises: a substrate, a reflection layer, a resonant cavity layer, a microstructure array layer, a lead salt sensitive layer, a metal electrode layer, and a passivation layer;

[0009] The reflective layer is located on the upper surface of the substrate, the resonant cavity layer is located on the upper surface of the reflective layer, the microstructure array layer is located on the upper surface of the resonant cavity layer, the microstructure array layer is a nanoscale metal artificial plasma array, the lead salt sensitive layer covers the resonant cavity layer and the microstructure array layer, the metal electrode layer is located on the lead salt sensitive layer, and the passivation layer is located on the upper surface of the entire detector;

[0010] The metal electrode layer includes pixel electrodes and common electrodes, and there are two electrode distribution modes:

[0011] One is: the pixel electrode and the common electrode are respectively on both sides of the lead salt sensitive layer;

[0012] The second is that the common electrode is in a ring shape, and the pixel electrode is arranged at the center of the ring structure;

[0013] The substrate is any one of a silicon substrate, a silicon dioxide substrate, and a glass substrate;

[0014] The reflective layer is made of Al metal material with a thickness of 150nm to 200nm;

[0015] The resonant cavity layer is any one of CaF2, Si3N4, SiO2, and Al2O3 dielectric materials, and has a thickness of 500nm to 1.5μm.

[0016] An enhanced structure lead salt uncooled medium wave infrared detector, the detector structure comprising: a substrate, a reflection layer, a resonant cavity layer, a microstructure array layer, a lead salt sensitive layer, a metal electrode layer, and a passivation layer;

[0017] The reflective layer is located on the upper surface of the substrate, the resonant cavity layer is located on the upper surface of the reflective layer, the lead salt sensitive layer is located on the upper surface of the resonant cavity layer, the microstructure array layer is located on the upper surface of the lead salt sensitive layer, the microstructure array layer is a nanoscale metal artificial plasma excitation array, the metal electrode layer is located on the lead salt sensitive layer, the microstructure array layer does not contact each whole element in the metal electrode layer, and the passivation layer is located on the upper surface of the entire detector;

[0018] The metal electrode layer includes pixel electrodes and common electrodes, and there are two electrode distribution modes:

[0019] One is: the pixel electrode and the common electrode are respectively on both sides of the lead salt sensitive layer;

[0020] The second is that the common electrode is in a ring shape, and the pixel electrode is arranged at the center of the ring structure;

[0021] The substrate is any one of a silicon substrate, a silicon dioxide substrate, and a glass substrate;

[0022] The reflective layer is made of Al metal material with a thickness of 150nm to 200nm;

[0023] The resonant cavity layer is any one of CaF2, Si3N4, SiO2, and Al2O3 dielectric materials, and has a thickness of 500nm to 1.5μm.

[0024] Furthermore, the microstructure array layer is any one of the metal materials of Au, Al, and Ti, with a thickness of 20nm to 200nm; the microstructure is any one of periodically arranged cylinders, square columns, cross columns, various polygons, ellipses and related combinations thereof, with a typical diameter or side length of 200nm to 3μm and a typical center spacing of 300nm to 3.5μm.

[0025] Furthermore, the lead salt sensitive layer is any one of PbS, PbSe, and PbTe, with a thickness of 400nm to 1.5μm, and a pixel size between 3μm×3μm and 5mm×5mm.

[0026] Furthermore, the electrode material is made of any one of Au, Ti, Al, Ni, Ge, and Cr, or an alloy of at least two of them, and has a thickness of 20 to 150 nm.

[0027] Furthermore, the passivation layer is any one of CaF2, Si3N4, SiO2, ZnS, and TiN, and has a thickness of 50 to 300 nm.

[0028] A method for preparing an enhanced structured lead salt uncooled medium-wave infrared detector comprises the following steps:

[0029] Step 1: preparing a metal reflective layer on the surface of the substrate;

[0030] A reflective layer is grown on the surface of the substrate by magnetron sputtering; Al is selected as the target material, vacuum is drawn, the sputtering power is set, argon is introduced as the sputtering gas, the gas pressure is adjusted to a stable working pressure, the magnetron sputtering source is started, and reflective layers of different thicknesses are formed by controlling the sputtering time;

[0031] Step 2: preparing a resonant cavity layer on the reflective layer;

[0032] A resonant cavity layer is grown on the surface of the reflective layer by a magnetron sputtering method; a target material such as CaF2, Si3N4, SiO2 or Al2O3 is selected, a vacuum is drawn, and a sputtering power is set; argon gas is introduced as a sputtering gas, the gas pressure is adjusted to a stable working pressure, a magnetron sputtering source is started, and a resonant cavity layer of different thicknesses is formed by controlling the sputtering time;

[0033] Step 3: preparing a metal layer on the resonant cavity layer and etching to obtain a microstructure array layer;

[0034] Step 4: preparing a lead salt sensitive layer on the microstructure array layer;

[0035] Step 5: sensitizing the lead salt sensitive layer material and etching it into sensitive units of a set size;

[0036] Step 6: preparing an electrode layer on the lead salt sensitive layer;

[0037] Step 7: Finally, prepare the passivation layer.

[0038] Furthermore, the step of forming a microstructure array layer in step 3 includes:

[0039] Using photolithography technology combined with etching process, photoresist is evenly coated on the resonant cavity layer, and a microstructure array layer pattern is obtained by etching;

[0040] The magnetron sputtering method is used to grow metal films. The target material is selected as one of Au, Al or Ti. The film is vacuumed, the sputtering power is set, argon is introduced as the sputtering gas, the working pressure is adjusted, the sputtering source is started, and the sputtering time is controlled to obtain metal films of different thicknesses. The film is cleaned with organic solvents such as acetone and alcohol, and dried with N2 to obtain a surface microstructure metal array layer.

[0041] The step of forming the lead salt sensitive layer in step 4 includes:

[0042] growing the lead salt sensitive layer by one of magnetron sputtering, vacuum evaporation or chemical bath deposition;

[0043] The magnetron sputtering method is as follows: select one of the target materials PbS, PbSe or PbTe, evacuate, set the sputtering power; introduce argon as the sputtering gas, adjust the working gas pressure, start the sputtering source, and control the sputtering time to obtain lead salt films of different thicknesses;

[0044] The vacuum evaporation method is as follows: the lead salt material is heated to the evaporation temperature, so that it evaporates in a vacuum and is deposited on the surface of the metal disk array layer to obtain a lead salt sensitive layer;

[0045] The chemical bath deposition method is as follows: the substrate is immersed in a solution containing a lead salt precursor, and a thin film is deposited through a chemical reaction to obtain a lead salt sensitive layer;

[0046] The step of sensitizing the lead salt sensitive layer material in step 5 includes:

[0047] Sensitize the lead salt film by oxygen sensitization, iodine sensitization or water bath method;

[0048] Oxygen sensitization is as follows: placing the substrate in the center of a tube furnace, first oxidizing in the air, and using the lead salt material as an evaporation source material along the flow direction of the carrier gas from upstream to downstream, setting the substrate, evacuating, first heating, then keeping the temperature, and finally cooling to obtain a sensitized lead salt material film;

[0049] Iodine sensitization is as follows: iodine is vaporized and introduced into a reactor to react with a lead salt film placed therein at a certain temperature and pressure;

[0050] The water bath sensitization method is: the lead salt sensitive layer is placed in a water solution at a specific temperature, and the temperature and time of the water bath are controlled to make the sensitive layer undergo a sensitization reaction under the action of the water solution;

[0051] After sensitization is completed, a wet etching or dry etching process is used to etch into sensitive unit structures of different sizes by controlling parameters such as etching time and solution concentration;

[0052] The step of forming the metal electrode layer in step 6 includes:

[0053] The metal electrode layer is prepared by vacuum evaporation, the mask is covered on the substrate, vacuum is drawn, and any one or an alloy of at least two of the metal materials Au, Ti, Al, Ni, Ge, Cr is heated to evaporate in vacuum and deposit on the surface of the sensitive layer to obtain the metal electrode layer; or the metal electrode layer based on the above metal materials is prepared by magnetron sputtering;

[0054] The step of forming a passivation layer in step 7 includes:

[0055] Grow the passivation layer by magnetron sputtering; select any one of the target materials CaF2, Si3N4, SiO2, ZnS, TiN, evacuate the vacuum, and set the sputtering power; introduce argon as the sputtering gas, adjust the gas pressure to a stable working pressure, start the magnetron sputtering source, and form the passivation layer of different thicknesses by controlling the sputtering time.

[0056] A method for preparing an enhanced structured lead salt uncooled medium-wave infrared detector comprises the following steps:

[0057] Step 1: preparing a metal reflective layer on the surface of the substrate;

[0058] A reflective layer is grown on the surface of the substrate by magnetron sputtering; Al is selected as the target material, vacuum is drawn, the sputtering power is set, argon is introduced as the sputtering gas, the gas pressure is adjusted to a stable working pressure, the magnetron sputtering source is started, and reflective layers of different thicknesses are formed by controlling the sputtering time;

[0059] Step 2: preparing a resonant cavity layer on the reflective layer;

[0060] A resonant cavity layer is grown on the surface of the reflective layer by a magnetron sputtering method; a target material such as CaF2, Si3N4, SiO2 or Al2O3 is selected, a vacuum is drawn, and a sputtering power is set; argon gas is introduced as a sputtering gas, the gas pressure is adjusted to a stable working pressure, a magnetron sputtering source is started, and a resonant cavity layer of different thicknesses is formed by controlling the sputtering time;

[0061] Step 3: preparing a lead salt sensitive layer on the resonant cavity layer;

[0062] Step 4: sensitizing the lead salt sensitive layer;

[0063] Step 5: Prepare a microstructure array layer on the lead salt sensitive layer.

[0064] Step 6: preparing an electrode layer on the lead salt sensitive layer;

[0065] Step 7: Finally, prepare the passivation layer.

[0066] Furthermore, the step of forming the lead salt sensitive layer in step 3 includes:

[0067] growing the lead salt sensitive layer by one of magnetron sputtering, vacuum evaporation or chemical bath deposition;

[0068] The magnetron sputtering method is as follows: select one of the target materials PbS, PbSe or PbTe, evacuate, set the sputtering power; introduce argon as the sputtering gas, adjust the working gas pressure, start the sputtering source, and control the sputtering time to obtain lead salt films of different thicknesses;

[0069] The vacuum evaporation method is as follows: the lead salt material is heated to the evaporation temperature, so that it evaporates in a vacuum and is deposited on the surface of the metal disk array layer to obtain a lead salt sensitive layer;

[0070] The chemical bath deposition method is as follows: the substrate is immersed in a solution containing a lead salt precursor, and a thin film is deposited through a chemical reaction to obtain a lead salt sensitive layer;

[0071] The step of sensitizing the lead salt sensitive layer material in step 4 includes:

[0072] Sensitize the lead salt film by oxygen sensitization, iodine sensitization or water bath method;

[0073] Oxygen sensitization is as follows: placing the substrate in the center of a tube furnace, first oxidizing in the air, and using the lead salt material as an evaporation source material along the flow direction of the carrier gas from upstream to downstream, setting the substrate, evacuating, first heating, then keeping the temperature, and finally cooling to obtain a sensitized lead salt material film;

[0074] Iodine sensitization is as follows: iodine is vaporized and introduced into a reactor to react with a lead salt film placed therein at a certain temperature and pressure;

[0075] The water bath sensitization method is: the lead salt sensitive layer is placed in a water solution at a specific temperature, and the temperature and time of the water bath are controlled to make the sensitive layer undergo a sensitization reaction under the action of the water solution;

[0076] After sensitization is completed, a wet etching or dry etching process is used to etch into sensitive unit structures of different sizes by controlling parameters such as etching time and solution concentration;

[0077] The step of forming the microstructure array layer in step 5 includes:

[0078] Using photolithography technology combined with etching process, photoresist is evenly coated on the resonant cavity layer, and a microstructure array layer pattern is obtained by etching;

[0079] The metal film is grown by magnetron sputtering, and the target material is selected as one of Au, Al or Ti, vacuum is drawn, the sputtering power is set, argon is introduced as the sputtering gas, the working pressure is adjusted, the sputtering source is started, and the sputtering time is controlled to obtain metal films of different thicknesses; the metal film is cleaned with organic solvents such as acetone and alcohol, and dried with N2 to obtain a surface microstructure metal array layer;

[0080] The step of forming the metal electrode layer in step 6 includes:

[0081] The metal electrode layer is prepared by vacuum evaporation, the mask is covered on the substrate, vacuum is drawn, and any one or an alloy of at least two of the metal materials Au, Ti, Al, Ni, Ge, Cr is heated to evaporate in vacuum and deposit on the surface of the sensitive layer to obtain the metal electrode layer; or the metal electrode layer based on the above metal materials is prepared by magnetron sputtering;

[0082] The step of forming a passivation layer in step 7 includes:

[0083] Grow the passivation layer by magnetron sputtering; select any one of the target materials CaF2, Si3N4, SiO2, ZnS, TiN, evacuate the vacuum, and set the sputtering power; introduce argon as the sputtering gas, adjust the gas pressure to a stable working pressure, start the magnetron sputtering source, and form the passivation layer of different thicknesses by controlling the sputtering time.

[0084] The present invention has at least one of the following beneficial effects:

[0085] The present invention designs a lead salt uncooled medium-wave infrared detector based on an artificial plasma exciton array. A resonant structure consisting of a metal reflective layer and a resonant cavity layer is deposited in sequence, and a microstructure array layer is prepared by photolithography and etching processes. Through the optical coupling of the resonant cavity and the local field enhancement effect of LSPR, the incident light energy is concentrated on the lead salt sensitive layer, which can effectively improve the light absorption rate and enhance the photoelectric response performance of the device.

[0086] The present invention adopts oxidation, iodination or water bath method to treat lead salt thin film. These two methods are simple to operate, low in cost, and can significantly improve the photoelectric properties of lead selenide. By controlling the temperature and immersion time under a suitable chemical atmosphere, the photoelectric properties of the film surface can be enhanced, the dark current can be reduced, and the response sensitivity can be improved. The invention adopts a multi-layer design structure, which can improve light absorption, enhance the sensitivity and stability of the detector, improve the light absorption efficiency of the lead salt material in the mid-infrared band, and realize miniaturized, low-cost, and highly sensitive infrared detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0087] Figure 1 Schematic diagram of the growth process of the PbSe mid-infrared detector based on the artificial plasma exciton array in Invention Example 1.

[0088] Figure 2 This is a scanning electron microscope surface morphology image of the Al film obtained in Example 1 of the present invention.

[0089] Figure 3 This is a reflection spectrum diagram of the Al film with a thickness of 200 nm in Example 1 of the present invention in the medium band (3-6 μm).

[0090] Figure 4This is a scanning electron microscope surface morphology image of the CaF2 film obtained in Example 1 of the present invention.

[0091] Figure 5 Spectral transmittance of the CaF2 film with a thickness of 1.2 μm in the middle band (3-6 μm) of Example 1 of the present invention.

[0092] Figure 6 This is a scanning electron microscope surface morphology image of the PbSe film before sensitization in Example 1 of the present invention.

[0093] Figure 7 This is a scanning electron microscope surface morphology image of the sensitized PbSe film in Example 1 of the present invention.

[0094] Figure 8 This is the structure of the infrared detector according to embodiment 2 of the present invention. Specific implementation plan

[0095] In order to make the technical problems, technical solutions and beneficial effects solved by the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0096] An embodiment of the present invention provides a lead salt uncooled medium-wave infrared detector based on an artificial plasma exciton array. The detector junction includes: a substrate, a reflective layer grown on the upper surface of the substrate, a resonant cavity layer grown on the upper surface of the reflective layer, a microstructure array layer grown on the upper surface of the resonant cavity layer, a lead salt sensitive layer grown on the upper surface of the microstructure array layer, a metal electrode layer grown on the upper surface of the lead salt sensitive layer, and a passivation layer grown on the upper surfaces of the lead salt sensitive layer and the electrode layer.

[0097] In some embodiments, the substrate is a silicon substrate.

[0098] In some embodiments, the reflective layer is an Al thin film with a thickness of 200 nm.

[0099] In some embodiments, the resonant cavity layer is a CaF2 film with a thickness of 1.2 μm.

[0100] In some embodiments, the microstructure array layer is a Ti thin film with a thickness of 60 nm.

[0101] The microstructure is a circular disk arranged periodically, the diameter of the disk is 3 μm, and the center distance between two disks is 3.5 μm.

[0102] In some embodiments, the lead salt sensitive layer is a PbSe thin film with a thickness of 700 nm.

[0103] In some embodiments, the metal electrode layer is an Au thin film with a thickness of 80 nm.

[0104] In some embodiments, the passivation layer is a Si3N4 film with a thickness of 200 nm.

[0105] Another embodiment of the present invention provides a method for preparing a lead salt uncooled medium-wave infrared detector with an enhanced structure, comprising the following steps:

[0106] Step 1: preparing a metal reflective layer on the surface of the substrate;

[0107] Step 2: preparing a resonant cavity layer on the reflective layer;

[0108] Step 3: preparing a metal layer on the resonant cavity layer and etching to obtain a microstructure array layer;

[0109] Step 4: preparing a lead salt sensitive layer on the microstructure array layer;

[0110] Step 5: sensitizing the lead salt sensitive layer material and etching it into sensitive units of a certain size;

[0111] Step 6: preparing an electrode on the lead salt sensitive layer and etching it;

[0112] Step 7: Finally, prepare the passivation layer.

[0113] In some embodiments, the step of forming a reflective layer in step 1 comprises: preparing a reflective layer on the surface of a silicon substrate by a magnetron sputtering method, selecting an Al target material, and evacuating the surface to 7×10 -4 Pa, set the sputtering power, introduce a small amount of argon as the sputtering gas, adjust the gas pressure to a stable working pressure, start the magnetron sputtering source, set the sputtering time, and obtain the Al reflective layer.

[0114] In some embodiments, the step of forming the resonant cavity layer in step 2 includes: preparing the resonant cavity layer on the surface of the reflective layer by magnetron sputtering, selecting CaF2 target material, and evacuating to 7×10 -4 Pa, set the sputtering power, introduce a small amount of argon as the sputtering gas, adjust the gas pressure to a stable working pressure, start the magnetron sputtering source, set the sputtering time, and obtain the CaF2 resonant cavity layer.

[0115] In some embodiments, the step of forming a microstructure array layer in step 3 includes: using photolithography technology combined with an etching process to evenly coat photoresist on the CaF2 resonant cavity layer, pre-baking, exposing, post-baking, developing, observing the pattern, preparing a metal film by magnetron sputtering, selecting a Ti target material, evacuating to below 7×10-4Pa, setting the sputtering power, introducing a small amount of argon as a sputtering gas, adjusting the gas pressure to a stable working pressure, starting the sputtering source, setting the sputtering time, cleaning with organic solvents such as acetone and alcohol, and drying with N2 to obtain a metal Ti disk array layer.

[0116] In some embodiments, the step of forming the lead salt sensitive layer in step 4 includes: preparing the lead salt sensitive layer by vacuum evaporation, evacuating, heating the PbSe material to the evaporation temperature, evaporating it in vacuum and depositing it on the surface of the metal disk array layer to obtain the PbSe sensitive layer. Combined with photolithography and etching processes, etching into a unit structure of a certain size.

[0117] In some embodiments, the step of sensitizing the lead salt sensitive layer material in step 5 includes: placing a substrate with a PbSe thin film in a tube furnace and oxidizing it in the air; then placing an I evaporation source and a substrate in sequence along the flow direction of the carrier gas from upstream to downstream, evacuating, setting the heating temperature of the evaporation source and the substrate, and setting the reaction time; the heating rate of the powder in the heating stage is ≤10°C / min; after sensitization is completed, a wet etching process is used to etch the lead salt sensitive layer into a sensitive unit structure of a certain size.

[0118] In some embodiments, the step of forming a metal electrode layer in step 6 includes: preparing an Au electrode layer by vacuum evaporation, covering a strip mask on the substrate, evacuating the vacuum, heating the evaporation source material, causing it to evaporate in a vacuum and deposit on the surface of the sensitizing layer to obtain an Au electrode layer.

[0119] In some embodiments, the step of forming the passivation layer in step 7 includes: preparing the passivation layer by magnetron sputtering, selecting Si3N4 target material, evacuating to 7×10 -4 Pa, set the sputtering power, introduce a small amount of argon and nitrogen as sputtering gas, adjust the gas pressure to a stable working pressure, start the magnetron sputtering source, set the sputtering time, and obtain the Si3N4 resonant cavity layer.

[0120] The present invention is further described in detail below with specific examples, but the present invention is not limited to the following specific examples.

[0121] Example 1

[0122] This embodiment provides a PbSe mid-infrared detector based on an artificial plasmon array and a preparation method thereof, which specifically comprises the following steps:

[0123] Schematic diagram of the growth process of preparing PbSe mid-infrared detectors Figure 1 As shown, including:

[0124] (1) A Si substrate was used, and acetone and anhydrous ethanol were used for ultrasonic cleaning for 15 minutes in sequence to remove organic impurities on the surface of the substrate. Ultrapure water was used for ultrasonic cleaning for 10 minutes to remove the cleaning solvent remaining on the surface of the substrate. Finally, the substrate was dried with N2.

[0125] (2) Growth of Al reflective layer. A magnetron sputtering coating machine was used as the deposition growth equipment, and high-purity Al bulk crystal material was used as the target material. The Si substrate was fixed on the substrate tray and transferred to the sputtering chamber. The mechanical pump and molecular pump were evacuated to a vacuum degree of 7×10 -4 Pa, control the argon flow rate to 40sccm, set the working pressure to 0.5Pa, set the power to 80W, set the tray speed to 10r / min, and DC sputter for 30min to obtain an Al film with a thickness of 200nm.

[0126] (3) Growth of CaF2 resonant cavity layer. Based on the Al substrate that has been grown, a magnetron sputtering coating machine is used as the deposition growth equipment, and high-purity CaF2 bulk crystal material is used as the target material. Based on the Al reflective layer that has been grown, the vacuum is pumped to 7×10 -4 Pa, heat the substrate temperature to 60℃ for formal sputtering, set the chamber pressure to 0.5Pa, the sputtering power to 120W, control the argon flow rate to 30sccm, set the tray speed to 10r / min, turn off the heating power after RF sputtering for 90min, and naturally cool to room temperature to obtain a CaF2 film with a thickness of 1.2μm.

[0127] (4) Preparation of metal Ti disk array layer. On the basis of the CaF2 substrate, spin-coat the negative photoresist NR-3000, pre-bake for 2.5 min to remove the solvent, transfer the pattern on the mask to the photoresist by ultraviolet (MV) exposure for 7.5 s, post-bake for 2.5 min, develop for 20 s, and obtain periodically arranged circular holes; use a magnetron sputtering coating machine as the deposition growth equipment, high-purity Ti bulk crystal material as the target material, and evacuate to a vacuum degree of 7×10 -4 Pa, the argon flow rate was set to 20 sccm, the working pressure was set to 0.5 Pa, the power was set to 50 W, the tray speed was set to 10 r / min, and the sputtering was ended after 12 minutes of DC sputtering. The excess photoresist was cleaned with acetone, alcohol and other organic solvents. After N2 drying, a metal Ti disk array with a thickness of 60 nm was obtained, the disk diameter was 3 μm, and the center distance between the two disks was 3.5 μm.

[0128] (5) Growth of PbSe sensitive layer: 1.0 g of PbSe (99.99%) was used as an evaporation source and the substrate was placed in an evaporator and the vacuum was evacuated to 2 × 10 -3 Pa, heat the evaporation source material to 620°C, control the evaporation rate to 0.2A / s, and deposit for 6.5h to obtain a 700nm thick PbSe film.

[0129] (6) The PbSe film is oxidized and iodinated. On the basis of the grown PbSe film, air is used as a sensitizing source, the grown PbSe substrate is placed in the center of a horizontal tube furnace, heated to 460°C at a heating rate of 20°C / min, kept at 460°C for 30 minutes, and then cooled to room temperature at 10°C / min in three stages to oxidize the PbSe film; along the flow direction of the carrier gas from upstream to downstream, 0.5g of I (99.9%) is placed in the center of the horizontal tube furnace as an evaporation source, the substrate is set at the end of the furnace 5cm away from the outlet, after the tube furnace is sealed, a mechanical pump is used to evacuate the vacuum to 3Pa, the argon flow rate is controlled to be 25sccm, the heating temperature of the evaporation source material is set to 105°C, the substrate temperature is set to 325°C, the time for the tube furnace to heat up from room temperature to the heating temperature (105°C) of the evaporation source material is 17min, the steam formed by the reaction source is transported by the carrier gas to the surface of the grown PbSe substrate for reaction for 6min, the heating power of the tube furnace is cut off, and the furnace body is naturally cooled to room temperature to obtain a sensitized PbSe film.

[0130] (7) After sensitization, the photolithography and etching processes are combined, and the photoresist is used as a mask. After exposure and development, wet etching is used to etch into a 1 mm × 1 mm unit structure. The PbSe film is cleaned with ultrapure water and dried with N2.

[0131] (8) Prepare Au electrodes on the PbSe film, design a strip mask shape according to the area of ​​the prepared PbSe film, cover the mask on the PbSe film, and use an evaporation coating equipment to evaporate the gold electrode. Control the evaporation rate to 1 A / s, and deposit for about 20 minutes to obtain an 80 nm thick Au film.

[0132] (9) Growth of Si3N4 passivation layer, using magnetron sputtering coating machine as deposition growth equipment, high-purity Si3N4 bulk crystal material as target material, vacuum pumped to 7×10 -4 Pa, set the gas flow Ar:N2=30:10 (sccm), the working pressure to 0.5Pa, the power to 80W, the tray speed to 10r / min, and RF sputtering for 100min to obtain a Si3N4 film with a thickness of 200nm.

[0133] Example 2

[0134] An enhanced structure lead salt uncooled medium wave infrared detector, the detector structure comprising: a substrate, a reflection layer, a resonant cavity layer, a microstructure array layer, a lead salt sensitive layer, a metal electrode layer, and a passivation layer;

[0135] The reflective layer is located on the upper surface of the substrate, the resonant cavity layer is located on the upper surface of the reflective layer, the lead salt sensitive layer is located on the upper surface of the resonant cavity layer, the microstructure array layer is located on the upper surface of the lead salt sensitive layer, the microstructure array layer is a nanoscale metal artificial plasma excitation array, the metal electrode layer is located on the lead salt sensitive layer, the microstructure array layer does not contact each whole element in the metal electrode layer, and the passivation layer is located on the upper surface of the entire detector;

[0136] The metal electrode layer includes pixel electrodes and common electrodes, and there are two electrode distribution modes:

[0137] One is: the pixel electrode and the common electrode are respectively on both sides of the lead salt sensitive layer;

[0138] The second is that the common electrode is in a ring shape, and the pixel electrode is arranged at the center of the ring structure;

[0139] The substrate is any one of a silicon substrate, a silicon dioxide substrate, and a glass substrate;

[0140] The reflective layer is made of Al metal material with a thickness of 150nm to 200nm;

[0141] The resonant cavity layer is any one of CaF2, Si3N4, SiO2, and Al2O3 dielectric materials, and has a thickness of 500nm to 1.5μm.

[0142] The microstructure array layer is any one of the metal materials of Au, Al, and Ti, with a thickness of 20nm to 200nm; the microstructure is any one of periodically arranged cylinders, square columns, cross columns, various polygons, ellipses and related combinations thereof, with a typical diameter or side length of 200nm to 3μm and a typical center spacing of 300nm to 3.5μm.

[0143] The lead salt sensitive layer is any one of PbS, PbSe and PbTe, with a thickness of 400nm to 1.5μm, and a pixel size of 3μm×3μm-5mm×5mm.

[0144] The electrode material is made of any one of Au, Ti, Al, Ni, Ge, and Cr or an alloy of at least two of them, and has a thickness of 20 to 150 nm.

[0145] The passivation layer is any one of CaF2, Si3N4, SiO2, ZnS and TiN, and has a thickness of 50 to 300 nm.

[0146] This method can be used to obtain a lead salt uncooled medium-wave infrared detector based on an artificial plasmon array.

[0147] Figure 2 The scanning electron microscope surface morphology image of the Al reflective layer obtained in this Example 1 shows the high continuity of the Al film over a large area.

[0148] Figure 3 This is the reflection spectrum of the Al film with a thickness of 200 nm in this embodiment 1. The reflectivity in the mid-wave band (3 to 6 μm) is obtained by Fourier transform infrared spectrometer (FT-IR). Since its thickness is much larger than the skin depth of the mid-infrared wave inside the aluminum metal layer, the infrared wave is almost totally reflected at the bottom layer of the structure.

[0149] Figure 4 The scanning electron microscope surface morphology of the CaF2 film obtained in Example 1 has a high degree of crystallinity, which is due to the orderly arrangement of atoms on the substrate during the sputtering process. Films with high crystallinity often have better performance.

[0150] Figure 5 This is the transmission spectrum of the CaF2 film with a thickness of 1.2μm in this embodiment 1. The transmittance in the mid-band (3-6μm) is obtained by Fourier transform infrared spectrometer (FT-IR). The sharp drop at 3.6μm is due to the absorption of the mica substrate and is negligible. The average transmittance is as high as over 80%. This broadband high transmittance characteristic is an important advantage as a resonant cavity.

[0151] Figure 6 This is a scanning electron microscope surface morphology image of the PbSe film in Example 1 before sensitization, which shows good crystal quality, clear boundaries between particles, and no obvious defects or impurities.

[0152] Figure 7 This is a scanning electron microscope surface morphology image of the PbSe film after oxidation and iodination treatment in this embodiment 1. The sensitization treatment promotes the fusion or agglomeration between the particles, resulting in an increase in the particle size. Larger crystal particles help to reduce the number of grain boundaries and reduce the scattering and capture effects of grain boundaries on carriers, which is beneficial to increase the number of photogenerated carriers and improve the responsiveness of the detector.

[0153] Figure 8 This is a structural diagram of Example 2.

[0154] Although the above embodiment describes the present invention in detail, it is only a part of the embodiments of the present invention, not all of the embodiments. Other embodiments can be obtained based on this embodiment without creativity, and these embodiments all fall within the protection scope of the present invention.

Claims

1. An enhanced structure lead salt uncooled medium wave infrared detector, the detector structure comprising: Substrate, reflection layer, resonant cavity layer, microstructure array layer, lead salt sensitive layer, metal electrode layer, passivation layer; The reflective layer is located on the upper surface of the substrate, the resonant cavity layer is located on the upper surface of the reflective layer, the microstructure array layer is located on the upper surface of the resonant cavity layer, the microstructure array layer is a nanoscale metal artificial plasma array, the lead salt sensitive layer covers the resonant cavity layer and the microstructure array layer, the metal electrode layer is located on the lead salt sensitive layer, and the passivation layer is located on the upper surface of the entire detector; The metal electrode layer includes pixel electrodes and common electrodes, and there are two electrode distribution modes: One is: the pixel electrode and the common electrode are respectively on both sides of the lead salt sensitive layer; The second is that the common electrode is in a ring shape, and the pixel electrode is arranged at the center of the ring structure; The substrate is any one of a silicon substrate, a silicon dioxide substrate, and a glass substrate; The reflective layer is made of Al metal material with a thickness of 150nm to 200nm; The resonant cavity layer is any one of CaF2, Si3N4, SiO2, and Al2O3 dielectric materials, and has a thickness of 500nm to 1.5μm.

2. An enhanced structure lead salt uncooled medium wave infrared detector, the detector structure comprising: Substrate, reflection layer, resonant cavity layer, microstructure array layer, lead salt sensitive layer, metal electrode layer, passivation layer; The reflective layer is located on the upper surface of the substrate, the resonant cavity layer is located on the upper surface of the reflective layer, the lead salt sensitive layer is located on the upper surface of the resonant cavity layer, the microstructure array layer is located on the upper surface of the lead salt sensitive layer, the microstructure array layer is a nanoscale metal artificial plasma excitation array, the metal electrode layer is located on the lead salt sensitive layer, the microstructure array layer does not contact each whole element in the metal electrode layer, and the passivation layer is located on the upper surface of the entire detector; The metal electrode layer includes pixel electrodes and common electrodes, and there are two electrode distribution modes: One is: the pixel electrode and the common electrode are respectively on both sides of the lead salt sensitive layer; The second is that the common electrode is in a ring shape, and the pixel electrode is arranged at the center of the ring structure; The substrate is any one of a silicon substrate, a silicon dioxide substrate, and a glass substrate; The reflective layer is made of Al metal material with a thickness of 150nm to 200nm; The resonant cavity layer is any one of CaF2, Si3N4, SiO2, and Al2O3 dielectric materials, and has a thickness of 500nm to 1.5μm.

3. An enhanced structure lead salt uncooled medium wave infrared detector as claimed in claim 1 or 2, characterized in that: The microstructure array layer is any one of the metal materials of Au, Al, and Ti, with a thickness of 20nm to 200nm; the microstructure is any one of periodically arranged cylinders, square columns, cross columns, various polygons, ellipses and related combinations thereof, with a typical diameter or side length of 200nm to 3μm and a typical center spacing of 300nm to 3.5μm.

4. The lead salt uncooled medium-wave infrared detector with enhanced structure as claimed in claim 1 or 2, characterized in that: The lead salt sensitive layer is any one of PbS, PbSe and PbTe, with a thickness of 400nm to 1.5μm, and a pixel size of 3μm×3μm-5mm×5mm.

5. The lead salt uncooled medium-wave infrared detector with enhanced structure as claimed in claim 1 or 2, characterized in that: The electrode material is made of any one of Au, Ti, Al, Ni, Ge, and Cr or an alloy of at least two of them, and has a thickness of 20 to 150 nm.

6. An enhanced structure lead salt uncooled medium wave infrared detector as claimed in claim 1 or 2, characterized in that: The passivation layer is any one of CaF2, Si3N4, SiO2, ZnS and TiN, and has a thickness of 50 to 300 nm.

7. A method for preparing an enhanced structure lead salt uncooled medium wave infrared detector, comprising the following steps: Step 1: preparing a metal reflective layer on the surface of the substrate; A reflective layer is grown on the surface of the substrate by magnetron sputtering; Al is selected as the target material, vacuum is drawn, the sputtering power is set, argon is introduced as the sputtering gas, the gas pressure is adjusted to a stable working pressure, the magnetron sputtering source is started, and reflective layers of different thicknesses are formed by controlling the sputtering time; Step 2: preparing a resonant cavity layer on the reflective layer; A resonant cavity layer is grown on the surface of the reflective layer by a magnetron sputtering method; a target material such as CaF2, Si3N4, SiO2 or Al2O3 is selected, a vacuum is drawn, and a sputtering power is set; argon gas is introduced as a sputtering gas, the gas pressure is adjusted to a stable working pressure, a magnetron sputtering source is started, and a resonant cavity layer of different thicknesses is formed by controlling the sputtering time; Step 3: preparing a metal layer on the resonant cavity layer and etching to obtain a microstructure array layer; Step 4: preparing a lead salt sensitive layer on the microstructure array layer; Step 5: sensitizing the lead salt sensitive layer material and etching it into sensitive units of a set size; Step 6: preparing an electrode layer on the lead salt sensitive layer; Step 7: Finally, prepare the passivation layer.

8. A method for preparing an enhanced structure lead salt uncooled medium wave infrared detector, comprising the following steps: Step 1: preparing a metal reflective layer on the surface of the substrate; A reflective layer is grown on the surface of the substrate by magnetron sputtering; Al is selected as the target material, vacuum is drawn, the sputtering power is set, argon is introduced as the sputtering gas, the gas pressure is adjusted to a stable working pressure, the magnetron sputtering source is started, and reflective layers of different thicknesses are formed by controlling the sputtering time; Step 2: preparing a resonant cavity layer on the reflective layer; A resonant cavity layer is grown on the surface of the reflective layer by a magnetron sputtering method; a target material such as CaF2, Si3N4, SiO2 or Al2O3 is selected, a vacuum is drawn, and a sputtering power is set; argon gas is introduced as a sputtering gas, the gas pressure is adjusted to a stable working pressure, a magnetron sputtering source is started, and a resonant cavity layer of different thicknesses is formed by controlling the sputtering time; Step 3: preparing a lead salt sensitive layer on the resonant cavity layer; Step 4: sensitizing the lead salt sensitive layer; Step 5: Prepare a microstructure array layer on the lead salt sensitive layer. Step 6: preparing an electrode layer on the lead salt sensitive layer; Step 7: Finally, prepare the passivation layer.

9. The method for preparing the lead salt uncooled medium-wave infrared detector with enhanced structure as claimed in claim 7, characterized in that: The step of forming the microstructure array layer in step 3 includes: Using photolithography technology combined with etching process, photoresist is evenly coated on the resonant cavity layer, and a microstructure array layer pattern is obtained by etching; The metal film is grown by magnetron sputtering, and the target material is selected as one of Au, Al or Ti, vacuum is drawn, the sputtering power is set, argon is introduced as the sputtering gas, the working pressure is adjusted, the sputtering source is started, and the sputtering time is controlled to obtain metal films of different thicknesses; the metal film is cleaned with organic solvents such as acetone and alcohol, and dried with N2 to obtain a surface microstructure metal array layer; The step of forming the lead salt sensitive layer in step 4 includes: growing the lead salt sensitive layer by one of magnetron sputtering, vacuum evaporation or chemical bath deposition; The magnetron sputtering method is as follows: select one of the target materials PbS, PbSe or PbTe, evacuate, set the sputtering power; introduce argon as the sputtering gas, adjust the working gas pressure, start the sputtering source, and control the sputtering time to obtain lead salt films of different thicknesses; The vacuum evaporation method is as follows: the lead salt material is heated to the evaporation temperature, so that it evaporates in a vacuum and is deposited on the surface of the metal disk array layer to obtain a lead salt sensitive layer; The chemical bath deposition method is as follows: the substrate is immersed in a solution containing a lead salt precursor, and a thin film is deposited through a chemical reaction to obtain a lead salt sensitive layer; The step of sensitizing the lead salt sensitive layer material in step 5 includes: Sensitize the lead salt film by oxygen sensitization, iodine sensitization or water bath method; Oxygen sensitization is as follows: placing the substrate in the center of a tube furnace, first oxidizing in the air, and using the lead salt material as an evaporation source material along the flow direction of the carrier gas from upstream to downstream, setting the substrate, evacuating, first heating, then keeping the temperature, and finally cooling to obtain a sensitized lead salt material film; Iodine sensitization is as follows: iodine is vaporized and introduced into a reactor to react with a lead salt film placed therein at a certain temperature and pressure; The water bath sensitization method is: the lead salt sensitive layer is placed in a water solution at a specific temperature, and the temperature and time of the water bath are controlled to make the sensitive layer undergo a sensitization reaction under the action of the water solution; After sensitization is completed, a wet etching or dry etching process is used to etch into sensitive unit structures of different sizes by controlling parameters such as etching time and solution concentration; The step of forming the metal electrode layer in step 6 includes: The metal electrode layer is prepared by vacuum evaporation, the mask is covered on the substrate, vacuum is drawn, and any one or an alloy of at least two of the metal materials Au, Ti, Al, Ni, Ge, Cr is heated to evaporate in vacuum and deposit on the surface of the sensitive layer to obtain the metal electrode layer; or the metal electrode layer based on the above metal materials is prepared by magnetron sputtering; The step of forming a passivation layer in step 7 includes: Grow the passivation layer by magnetron sputtering; select any one of the target materials CaF2, Si3N4, SiO2, ZnS, TiN, evacuate the vacuum, and set the sputtering power; introduce argon as the sputtering gas, adjust the gas pressure to a stable working pressure, start the magnetron sputtering source, and form the passivation layer of different thicknesses by controlling the sputtering time.

10. The method for preparing the lead salt uncooled medium-wave infrared detector with enhanced structure as claimed in claim 8, characterized in that: The step of forming the lead salt sensitive layer in step 3 includes: growing the lead salt sensitive layer by one of magnetron sputtering, vacuum evaporation or chemical bath deposition; The magnetron sputtering method is as follows: select one of the target materials PbS, PbSe or PbTe, evacuate, set the sputtering power; introduce argon as the sputtering gas, adjust the working gas pressure, start the sputtering source, and control the sputtering time to obtain lead salt films of different thicknesses; The vacuum evaporation method is as follows: the lead salt material is heated to the evaporation temperature, so that it evaporates in a vacuum and is deposited on the surface of the metal disk array layer to obtain a lead salt sensitive layer; The chemical bath deposition method is as follows: the substrate is immersed in a solution containing a lead salt precursor, and a thin film is deposited through a chemical reaction to obtain a lead salt sensitive layer; The step of sensitizing the lead salt sensitive layer material in step 4 includes: Sensitize the lead salt film by oxygen sensitization, iodine sensitization or water bath method; Oxygen sensitization is as follows: placing the substrate in the center of a tube furnace, first oxidizing in the air, and using the lead salt material as an evaporation source material along the flow direction of the carrier gas from upstream to downstream, setting the substrate, evacuating, first heating, then keeping the temperature, and finally cooling to obtain a sensitized lead salt material film; Iodine sensitization is as follows: iodine is vaporized and introduced into a reactor to react with a lead salt film placed therein at a certain temperature and pressure; The water bath sensitization method is: the lead salt sensitive layer is placed in a water solution at a specific temperature, and the temperature and time of the water bath are controlled to make the sensitive layer undergo a sensitization reaction under the action of the water solution; After sensitization is completed, a wet etching or dry etching process is used to etch into sensitive unit structures of different sizes by controlling parameters such as etching time and solution concentration; The step of forming the microstructure array layer in step 5 includes: Using photolithography technology combined with etching process, photoresist is evenly coated on the resonant cavity layer, and a microstructure array layer pattern is obtained by etching; The metal film is grown by magnetron sputtering, and the target material is selected as one of Au, Al or Ti, vacuum is drawn, the sputtering power is set, argon is introduced as the sputtering gas, the working pressure is adjusted, the sputtering source is started, and the sputtering time is controlled to obtain metal films of different thicknesses; the metal film is cleaned with organic solvents such as acetone and alcohol, and dried with N2 to obtain a surface microstructure metal array layer; The step of forming the metal electrode layer in step 6 includes: The metal electrode layer is prepared by vacuum evaporation, the mask is covered on the substrate, vacuum is drawn, and any one or an alloy of at least two of the metal materials Au, Ti, Al, Ni, Ge, Cr is heated to evaporate in vacuum and deposit on the surface of the sensitive layer to obtain the metal electrode layer; or the metal electrode layer based on the above metal materials is prepared by magnetron sputtering; The step of forming a passivation layer in step 7 includes: Grow the passivation layer by magnetron sputtering; select any one of the target materials CaF2, Si3N4, SiO2, ZnS, TiN, evacuate the vacuum, and set the sputtering power; introduce argon as the sputtering gas, adjust the gas pressure to a stable working pressure, start the magnetron sputtering source, and form the passivation layer of different thicknesses by controlling the sputtering time.

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