An infrared light detection device based on semi-metallic material and a preparation method thereof

Abstract

The present application relates to the field of infrared light measurement, and specifically provides an infrared light detection device based on semi-metallic materials and a preparation method thereof. The device includes a substrate, a semi-metallic material layer is provided on the substrate, and electrodes and a polymer material layer are provided on the surface of the semi-metallic material layer away from the substrate. The electrodes are provided at both ends, and the polymer material layer is provided between the two electrodes, and the polymer material layer is not in contact with the electrodes. The present application also provides a preparation method for an infrared light detection device based on a semi-metallic material, and the method includes the following steps: step one, depositing a semi-metallic material layer on the surface of the substrate; step two, spin coating a polymer material layer on the surface of the semi-metallic material layer; step three, preparing electrodes on both ends of the polymer material layer on the semi-metallic material layer. In the device of the present application, the polymer material layer plays a role of thermal isolation, so that the temperature of the semi-metallic material layer is reduced, thereby improving the conductive performance and the detection accuracy is higher.

Description

Technical Field

[0001] The present application relates to the field of infrared light measurement, and in particular, to an infrared light detection device based on semi-metallic materials and a preparation method thereof. Background Art

[0002] Infrared light refers to light waves with a wavelength range of approximately 0.75μm to 1000μm. Specifically, it is divided into near-infrared, short-wave infrared, medium-wave infrared, long-wave infrared, and far-infrared according to the wavelength range. Infrared light has the characteristics of thermal radiation, non-destructiveness, and strong smoke penetration. It is widely used in night vision and thermal imaging, medical diagnosis, remote sensing, geological exploration and other fields. Accurate detection of infrared light is critical to the realization of technologies such as clear thermal imaging and precise detection of pollutants in the air.

[0003] Semi-metallic materials are materials with partial metal and partial semiconductor properties, with conductivity between metal and semiconductor, and the Fermi level is located between the conduction band and the valence band. Semi-metallic materials usually have a wide band structure, can respond to a wide spectral range from near infrared to mid-infrared and far infrared, and have a strong response to infrared light; the electron and hole mobility in semi-metallic materials is high, the carrier lifetime is short, and fast photoelectric response can be achieved, which is very beneficial for infrared detection that requires high-frequency response such as high-speed communication and dynamic imaging; therefore, semi-metallic materials have a large market prospect in the field of infrared detection, as described in the paper titled "High-Index and Low-Loss Topological Insulators for Mid-InfraredNanophotonics: Bismuth and Antimony Chalcogenides" (ADVANCED OPTICALMATERIALS, 2024, 12, 18). However, due to the increase in carrier scattering and the increase in thermally excited carriers caused by high temperature (above 100°C), the detection performance of semi-metallic materials will decrease at high temperature. Specifically, high temperature will lead to enhanced lattice vibration (phonon), which will increase the scattering of electrons or holes, resulting in a decrease in carrier mobility, and then reduce the conductivity and photoelectric response of the material; at high temperatures, the number of thermally excited electrons and holes increases, and the carrier concentration increases, but due to the enhanced scattering effect, the overall conductivity will decrease, resulting in a decrease in conductive performance. When in use, infrared light is directly irradiated on the semi-metallic material, changing the conductive properties of the semi-metallic material, and detecting the change in the conductive properties of the semi-metallic material through electrodes and external circuits; the increase in temperature causes the conductive properties of the semi-metallic material to decrease, resulting in a decrease in the accuracy of infrared light detection.

[0004] In summary, at high temperatures, the accuracy of infrared light detection directly using semi-metallic materials is low. Summary of the invention

[0005] The purpose of the present invention is to analyze the following deficiencies in the above-mentioned prior art: the infrared light to be detected has a strong thermal effect, so it is not easy to improve the source of heat; the heat is isolated so that the temperature of the semi-metal material layer is reduced, thereby suppressing the increase of carrier scattering and the increase of thermally excited carriers, and the conductivity does not decrease significantly. In addition, semi-metal materials are easily decomposed and oxidized at high temperatures to form tellurites, which further reduce the conductivity and make the detection accuracy worse. That is, under strong infrared light irradiation, the temperature of the semi-metal material will not rise rapidly. Therefore, an infrared light detection device based on semi-metal materials and a preparation method thereof are provided to solve the problem of low accuracy of infrared light detection directly using semi-metal materials at high temperatures.

[0006] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0007] The present application provides an infrared light detection device based on a semi-metal material, the device includes a substrate, a semi-metal material layer is arranged on the substrate, an electrode and a polymer material layer are arranged on the surface of the semi-metal material layer away from the substrate, the electrodes are arranged at both ends, the polymer material layer is arranged between the two electrodes, and the polymer material layer is not in contact with the electrodes. During detection, the infrared light to be detected is irradiated on the polymer material layer, the temperature of the polymer material layer changes, and the temperature of the semi-metal material layer changes through heat transfer, thereby changing the resistance of the semi-metal material layer, and the resistance change of the semi-metal material layer is detected by two electrodes to realize the detection of infrared light; specifically, when the temperature rises, the electron-phonon scattering increases, resulting in an increase in the resistivity of the semi-metal material layer and an increase in the resistance.

[0008] In the present application, the infrared light to be detected is not directly irradiated on the semi-metal material layer, but directly irradiated on the polymer material layer. The polymer material layer has good thermal isolation properties, which reduces the heat conduction to the semi-metal material layer when irradiated with infrared light. The polymer material layer absorbs infrared light and converts light energy into heat energy, causing its own temperature to rise; the polymer material layer has a low thermal conductivity, which can effectively prevent the heat from the external environment from being directly conducted to the semi-metal material layer, reducing the influence of heat on the electronic structure and carrier behavior of the semi-metal material, and the heat energy will not be quickly transferred to the semi-metal material layer, thereby reducing the temperature rise of the semi-metal material layer. On the one hand, the noise and error caused by the temperature rise are reduced. The polymer material layer can absorb and buffer the thermal noise, reduce the generation of thermally excited carriers, and improve the signal-to-noise ratio, so as to more accurately detect smaller changes in the intensity of infrared light, and the detection accuracy is high. On the other hand, the thermal decomposition of the semi-metallic material caused by the temperature rise is avoided, and the thermoelectric conversion efficiency of the semi-metallic material layer will not be reduced. That is, when the infrared light intensity to be detected is large, the temperature of the semi-metallic material layer will not rise rapidly, so that the thermoelectric conversion efficiency of the semi-metallic material layer will not decrease, and the detection sensitivity will still maintain a high level. The detection sensitivity of the device of the present application is high at high temperature. In addition, the stability of the semi-metallic material layer is also strong. On the other hand, the polymer material layer helps to form a uniform temperature distribution on the semi-metallic material layer, avoid electron scattering and resistance changes caused by local temperature gradients, avoid local overheating and cooling, and reduce the influence of temperature gradients on electrical properties, thereby further improving the detection accuracy.

[0009] Furthermore, the semi-metal material layer is bismuth telluride or bismuth selenide. First, they have a strong response in the infrared band, a high thermoelectric conversion efficiency, and the same temperature change can cause a large change in conductivity. In addition, bismuth telluride and bismuth selenide have a high carrier mobility, which helps to improve the sensitivity of resistance changes, so that the resistance change of the semi-metal material layer is large. Then, in a high temperature environment, bismuth telluride and bismuth selenide have good stability, are not easy to decompose or change in physical and chemical properties, and ensure that the detector works stably under different temperature conditions; low thermal conductivity helps to maintain the temperature gradient of the detector, making the detection of resistance changes through electrodes more sensitive and accurate. In particular, bismuth selenide has the characteristics of a topological insulator, and its surface state is sensitive to infrared light, which can improve the detection sensitivity.

[0010] Furthermore, the thickness of the semi-metal material layer is 50-300nm. In this way, it can effectively absorb infrared light and maintain high thermoelectric performance, ensuring sufficient infrared light absorption. Thinner semi-metal materials are more sensitive to temperature changes. The semi-metal material layer can reach thermal equilibrium faster and respond more quickly to temperature changes caused by infrared light, shortening the response time of the detector, thereby improving the detector. Such thickness can also reduce the scattering of electrons and phonons, maintain high carrier mobility, and thus improve the performance of the detector.

[0011] Furthermore, the material of the polymer material layer is polyvinylidene fluoride. On the one hand, polyvinylidene fluoride has low thermal conductivity, which can effectively isolate heat, reduce the direct conduction of heat to the semi-metal material layer, and improve the sensitivity and accuracy of the infrared detector; it has good absorption capacity for infrared light and can enhance the photoelectric response. On the other hand, polyvinylidene fluoride has a high dielectric constant and will produce a polarization effect under infrared light irradiation, which can significantly change the conductive properties of the semi-metal material layer and improve the detection sensitivity. Specifically, under infrared light irradiation, the electric dipole moment inside the molecules in the polymer material layer is rearranged, resulting in changes in the electric field and charge distribution inside the material. This polarization change will generate surface charge, thereby forming an electric field; the electric field generated by the polarization effect will affect the carrier distribution and mobility in the semi-metal material layer, change the charge density in the semi-metal material layer, and thus change its conductive properties. The resistance change of the semi-metal material layer is more obvious, and the detection sensitivity is improved; the electric field generated by the polarization effect also helps to filter external noise, reduce interference with the conductive properties of the semi-metal material layer, improve the signal-to-noise ratio, and reduce noise interference. In addition, it remains stable at high temperatures and is not easy to decompose or deform, ensuring that the detector works normally in high temperature environments.

[0012] Furthermore, the thickness of the polymer material layer is 500nm-5μm. A thickness greater than 500nm can ensure that the polymer material layer produces a strong polarization effect, thereby improving the detection sensitivity. A thickness less than 5μm, on the one hand, ensures strong infrared light absorption, and on the other hand, avoids excessive thickness that causes photogenerated carriers to recombine during transmission, thereby reducing sensitivity. Within this thickness range, the polymer material layer provides a thermal isolation effect, reducing the heat caused by infrared light irradiation from being conducted to the semi-metal material layer, while also ensuring moderate heat conduction, so that temperature changes can be effectively transmitted to the semi-metal material layer, making resistance changes more obvious and easier to detect.

[0013] Furthermore, a depression is provided on the upper surface of the polymer material layer, and the depth of the depression is less than half of the thickness of the polymer material layer. The depression structure can enhance infrared light absorption, enhance polarization effect, and increase heat dissipation performance. Specifically, on the one hand, the surface depression forms a plurality of tiny light traps on the surface of the material, so that the incident light is reflected and scattered multiple times in the depression. The depression can enhance the number of reflections and scattering times inside the depression on the surface of the polymer material layer, increase the path length of the light in the polymer material layer, and at the same time, reduce the infrared light reflected upward from the surface of the polymer material layer, thereby improving the absorption efficiency of infrared light. On the other hand, the depression structure enhances the electric field and polarization effect in the edge area of ​​the groove; at the same time, the enhanced electric field helps to separate photogenerated carriers and reduce the recombination rate, thereby further improving the detection sensitivity. On the other hand, the depression increases the surface area of ​​the polymer material layer, helps to dissipate heat, reduces the operating temperature of the device, and prevents the temperature from rising, which reduces the detection sensitivity.

[0014] Furthermore, the depth of the depression is 100nm-1μm. Such a depth can enhance the light trapping effect, increase multiple reflections and scattering of light, effectively capture infrared light and enhance infrared light absorption, while not significantly affecting mechanical strength and heat dissipation performance.

[0015] Furthermore, zinc oxide particles are arranged on the upper surface of the polymer material layer, and the zinc oxide particles are arranged in the depression. The zinc oxide particles form a plurality of light traps in the depression of the polymer material layer, and the infrared light is localized in the zinc oxide particles, which enhances the interaction between the light field and the polymer material layer, and further increases the number of reflections and scatterings of the incident infrared light in the depression, thereby improving the absorption efficiency of the infrared light. The zinc oxide particles have good electrical properties, and a strong local electric field can be formed on their surface. The zinc oxide particles in the depression enhance the local electric field, so that the polarization effect of the polymer material layer under infrared light irradiation is enhanced, and the enhanced polarization effect affects the charge distribution between the polymer material layer and the semi-metal material layer, further changes the conductive properties of the semi-metal material layer, and changes the resistance of the semi-metal material layer more, thereby improving the detection sensitivity; at the same time, the electric field formed by the zinc oxide particles in the depression of the polymer material layer effectively separates the photogenerated electrons and holes in the polymer material layer, reduces its recombination rate, and thereby enables more carriers to migrate to the semi-metal material layer, resulting in a more obvious resistance change, thereby improving the detection sensitivity. The presence of zinc oxide particles increases the surface area of ​​the polymer material layer and has good thermal conductivity, which can provide an additional heat dissipation path. The zinc oxide particles in the depressions help dissipate the heat absorbed by the polymer material layer, reduce the operating temperature of the entire device, and prevent the temperature from rising too quickly, thereby maintaining the detection sensitivity at a high level.

[0016] The present application also provides a method for preparing an infrared light detection device based on a semi-metallic material, the method comprising the following steps:

[0017] Step 1: depositing a semi-metal material layer on the surface of the substrate;

[0018] Step 2: Spin-coating a polymer material layer on the surface of the semi-metal material layer;

[0019] Step 3: Prepare electrodes on both ends of the polymer material layer on the semi-metal material layer.

[0020] Furthermore, step 2 also includes preparing depressions on the surface of the polymer material layer by using photolithography and plasma etching technology.

[0021] Compared with the prior art, the present invention has the following beneficial effects: In the present application, a polymer material layer with low thermal conductivity is arranged on the upper surface of the semi-metal material layer; infrared light is irradiated on the surface of the polymer material layer, the polymer material layer absorbs energy, and the temperature rises. Due to the low thermal conductivity, the heat is not easily transferred to the semi-metal material layer below, and the semi-metal material layer plays a role of thermal isolation, which will not cause the temperature of the semi-metal material layer to rise rapidly, thereby avoiding the increase of carrier scattering, the increase of thermally excited carriers, and the decomposition of materials caused by high temperature, and will not cause the conductivity of the semi-metal material to decrease, and the detection accuracy is high. At the same time, the polarization effect in the polymer material layer will generate an electric field therein, and the formed electric field changes the charge density in the semi-metal material layer, thereby changing its conductive properties, and the resistance change of the semi-metal material layer is more obvious, thereby improving the sensitivity of detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 A schematic diagram of an infrared light detection device based on a semi-metallic material provided in Example 1 of the present invention;

[0023] Figure 2 This is a schematic diagram of providing depressions on the surface of a polymer material layer in an infrared light detection device based on a semi-metallic material provided in Example 1 of the present invention.

[0024] Icon: 10-substrate; 20-semi-metal material layer; 30-electrode; 40-polymer material layer. DETAILED DESCRIPTION

[0025] In order to make the implementation process of the present invention clearer, it will be described in detail below with reference to the accompanying drawings.

[0026] Embodiment 1:

[0027] The present invention provides an infrared light detection device based on semi-metallic materials, such as Figure 1As shown, the device includes a substrate 10, a semi-metal material layer 20, an electrode 30, and a polymer material layer 40. The material of the substrate 10 is silicon or glass, which provides support for each layer structure on the device. A semi-metal material layer 20 is provided on the substrate 10; the material of the semi-metal material layer 20 is bismuth telluride or bismuth selenide, the thickness of the semi-metal material layer 20 is 50-300nm, and the semi-metal material layer 20 is provided in the middle of the substrate 10, and the area is slightly smaller than the substrate 10. The upper surface of the semi-metal material layer 20, that is, the surface away from the substrate 10, is provided with an electrode 30 and a polymer material layer 40. The electrode 30 is fixedly provided at both ends of the semi-metal material layer 20, and is used to connect with an external circuit to detect the resistance change of the semi-metal material layer 20. A resistance detection instrument can also be used to connect the two electrodes 30 to detect the resistance. The material of the electrode 30 is one of gold, silver, aluminum, and chromium, and has good conductivity; the thickness of the electrode 30 is 200nm-500nm; the shape of the electrode 30 is not specifically limited, as long as it can play an electrical connection role, and can be rectangular, circular, etc. The polymer material layer 40 is arranged between the two electrodes 30, and the polymer material layer 40 does not contact the electrode 30. The material of the polymer material layer 40 is polyvinylidene fluoride; the thickness of the polymer material layer 40 is 500nm-5μm.

[0028] When in use, infrared light is irradiated on the polymer material layer 40 between the two electrodes 30, the temperature of the polymer material layer 40 rises, photogenerated electrons and photogenerated holes are generated on the polymer material layer 40, the two are separated, and the photogenerated electrons enter the semi-metal material layer 20 from the interface, the resistance of the semi-metal material layer 20 changes, and at the same time, the heat absorbed by the polymer material layer 40 is transferred to the semi-metal material layer 20, so that the resistance of the semi-metal material layer 20 changes with temperature; by detecting the change in the resistance of the semi-metal material layer 20, the change in the intensity of the incident infrared light is obtained, and infrared detection is achieved. The polymer material layer 40 reduces the transfer of heat, so that the temperature of the semi-metal material layer 20 drops, the decrease in conductivity caused by high temperature is weakened, and decomposition is avoided. Therefore, the accuracy and sensitivity of infrared detection are high.

[0029] Furthermore, a plurality of depressions are provided on the upper surface of the polymer material layer 40, and the depth of the depressions is less than half of the thickness of the polymer material layer 40, and the depth of the depressions is 100nm-1μm. The spacing between adjacent depression structures is equivalent to the width of the depression structures, which is 200nm-800nm; in this way, more depression structures can be provided to enhance the absorption of infrared light. The depressions are arranged in a rectangular array. The shape of the depressions can be a rectangular pit or a pointed cone. Preferably, the shape of the depressions is a pointed cone, such as Figure 2As shown. The lower end of the pointed cone forms a tip with a large curvature. The tip generates a higher electric field strength, and the local electric field is enhanced, which helps to improve the separation efficiency of photogenerated carriers and enhance the polarization effect and photoelectric response. The depressions in this application are multiple independent depressions, not grooves.

[0030] The present application also provides a method for preparing an infrared light detection device based on a semi-metallic material, the method comprising the following steps:

[0031] Step 1: Deposit a semi-metal material layer 20 on the surface of the substrate 10. First, clean the substrate 10 using ethanol, acetone, and deionized water, respectively. Each ultrasonic cleaning time is greater than 10 minutes to remove organic and inorganic impurities on the surface. Finally, dry the substrate to remove residual moisture. The preparation of the semi-metal material layer 20 can use chemical vapor deposition, physical vapor deposition, sputtering deposition, molecular beam epitaxy and other methods to prepare bismuth telluride and bismuth selenide. In this embodiment, chemical vapor deposition is used for deposition. Specifically, taking bismuth telluride as an example, the precursor powder BiCl 3 and TeCl 4 Placed in a quartz glass tube, the gaseous precursor reacts to generate bismuth telluride, which is deposited on a substrate 10 disposed downstream. After the deposition is completed, it is naturally cooled to room temperature. The carrier gas is argon, the deposition temperature is 380-420°C, and the deposition time is about 1h-1.5h.

[0032] Step 2, spin-coat the polymer material layer 40 on the surface of the semi-metal material layer 20; prepare the polyvinylidene fluoride film by spin coating, the concentration of the spin coating solution is 10-15% (weight percentage), dissolve the polyvinylidene fluoride powder in N, N-dimethylformamide (DMF), stir until completely dissolved, and form a uniform solution. The spin coating speed is 1500-2500rpm, the spin coating time is 30-50s, and after the spin coating is completed, dry it naturally to completely evaporate the solvent. After spin coating, vacuum dry it at 60°C to improve the crystallinity of the film, and obtain the prepared polyvinylidene fluoride film. Since it is difficult to control the shape of the spin-coated film during spin coating, the entire surface of the semi-metal material layer 20 will be spin-coated with polyvinylidene fluoride material. Therefore, before spin coating, a protective film covering the area of ​​the electrode 30 will be set on both sides of the semi-metal material layer 20. The protective film can be a plastic film. After the spin coating is completed, the protective film on it is peeled off to reserve the area for depositing the electrode 30.

[0033] Step 3: Prepare electrodes 30 on both ends of the polymer material layer 40 on the semi-metal material layer 20. Since no special electrode pattern is required, the electrodes 30 in this application are prepared by direct deposition, and are deposited in the reserved areas at both ends of the polymer material layer 40.

[0034] Furthermore, step 2 also includes preparing a depression on the surface of the polymer material layer 40 using a photolithography process and plasma etching technology. First, determine the size, position, and shape of the depression, apply a layer of photoresist on the surface of the polymer material layer 40, define the position and pattern of the depression using photolithography technology, use a mask and ultraviolet light to expose the photoresist, and obtain the desired pattern after development. The photoresist is removed from the area irradiated by ultraviolet light (at the depressed structure), and the photoresist is retained in the area not irradiated. Using plasma etching technology, the polymer material is selectively removed to form a depression. After etching is completed, a solvent is used to remove the residual photoresist and clean the surface of the polymer layer.

[0035] Embodiment 2:

[0036] On the basis of Example 1, zinc oxide particles are arranged on the upper surface of the polymer material layer 40, and the zinc oxide particles are partially arranged in the depression. The width of the zinc oxide particles is equivalent to the width of the depression structure, and the height of the zinc oxide particles is greater than the depth of the depression structure. The height of the zinc oxide particles is 1.5-2 times the width; in this way, infrared light can be localized between adjacent zinc oxide particles, and the infrared light is reflected multiple times between adjacent zinc oxide particles, which further improves the absorption of infrared light. At the same time, it also enhances the intensity of the polarization effect, so that the detection sensitivity is improved.

[0037] In preparation, a zinc oxide precursor solution can be used to spray on the surface of the polymer material layer 40. During spraying, a template is used to block and avoid spraying outside the depression. The solution fills the depression. The precursor solution can be a zinc nitrate solution or a zinc acetate solution. Then, it is sintered at 350-450°C for 30min-2h to generate zinc oxide particles. A spraying device can also be used to quickly spray zinc oxide particles onto the polymer material layer 40. At the same time, under the action of zinc oxide particles, multiple depressions are formed on the surface of the polymer material layer 40, and there is no need to prepare the depression structure in advance. Since it is difficult to control the position of the depression, the former method is used in this embodiment.

[0038] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. An infrared light detection device based on a semi-metal material, the device comprising a substrate, a semi-metal material layer is arranged on the substrate, characterized in that: An electrode and a polymer material layer are arranged on the surface of the semi-metal material layer away from the substrate, the electrodes are arranged at both ends, the polymer material layer is arranged between the two electrodes, and the polymer material layer is not in contact with the electrodes; the material of the polymer material layer is polyvinylidene fluoride, and the thickness of the polymer material layer is 500nm-5μm; the semi-metal material layer is bismuth telluride or bismuth selenide.

2. The infrared light detection device based on semi-metallic materials according to claim 1 is characterized in that: The thickness of the semi-metal material layer is 50-300 nm.

3. The infrared light detection device based on semi-metallic materials according to claim 2 is characterized in that: The upper surface of the polymer material layer is provided with a depression, and the depth of the depression is less than half of the thickness of the polymer material layer.

4. The infrared light detection device based on semi-metallic materials according to claim 3 is characterized in that: The depth of the depression is 100 nm-1 μm.

5. The infrared light detection device based on semi-metallic materials according to claim 4 is characterized in that: Zinc oxide particles are arranged on the upper surface of the polymer material layer, and the zinc oxide particles are arranged in the depression.

Images