Preparation and application of room temperature ferroelectric polarization semiconductor gas sensor

Abstract

The application belongs to the technical field of gas sensors, and more particularly relates to a room-temperature ferroelectric polarization semiconductor gas sensor and an application thereof. In the application, an alpha-In2Se3 nanosheet dispersion liquid is coated on a test electrode and an upper surface of a substrate not covered by the test electrode to form an alpha-In2Se3 gas-sensitive layer, and the gas-sensitive layer is polarized and regulated by using a corona polarization treatment. The gas sensor prepared by using the method can realize high-sensitivity and high-selectivity detection of typical gases (such as nitrogen oxide gas, ammonia gas, chlorine gas, ozone and the like) at room temperature, and the detection limit is as low as a ppb level, and the response performance of the gas sensor can be dynamically regulated by adjusting polarization parameters. The room-temperature ferroelectric polarization semiconductor gas sensor provided by the application has the advantages of simple structure, low power consumption, fast response and fast recovery, and is suitable for trace gas detection in the fields of environmental monitoring and industrial safety.

Description

Technical Field

[0001] This application belongs to the field of gas sensor technology, and more specifically, relates to the fabrication and application of a room temperature ferroelectric semiconductor gas sensor. Background Technology

[0002] As a core component of information sensing systems, sensors play a crucial role in data acquisition in environmental monitoring and industrial production, serving as the foundational hardware for building the intelligent Internet of Things. Among them, gas sensors can convert changes in the concentration of specific gas molecules in the environment into quantifiable electrical signals, playing an irreplaceable role in areas such as hazardous gas early warning, air pollution monitoring, and public safety protection.

[0003] Nitrogen oxides (NOx) x Gases such as nitric oxide (NO and NO2), ammonia, chlorine, and ozone are major contributors to the greenhouse effect, significantly impacting agriculture, the economy, health, air quality, water quality, and ecosystems. Therefore, there is an urgent need to develop gas sensors capable of real-time, highly sensitive, and highly selective detection.

[0004] Among various gas sensors, semiconductor gas sensors have attracted much attention due to their simple fabrication, low cost, and rapid response. However, traditional semiconductor gas sensors operate at high temperatures, typically above 150°C, to obtain sufficient response activity, resulting in high energy consumption and complex equipment. Furthermore, at room temperature, traditional semiconductor gas sensors exhibit slow gas adsorption-desorption kinetics, low response values, and poor recovery characteristics.

[0005] Therefore, there is an urgent need in the field to provide a gas sensor that can achieve high sensitivity and fast response / recovery speed at room temperature. Summary of the Invention

[0006] In view of the shortcomings of the prior art, the purpose of this application is to provide a room temperature ferroelectric semiconductor gas sensor and its application, which aims to solve the problems of low response sensitivity and high detection limit that commonly exist in existing semiconductor gas sensors when detecting typical gases (such as nitrogen oxides, ammonia, chlorine, ozone, etc.) at room temperature.

[0007] To achieve the above objectives, in a first aspect, this application provides a method for fabricating a room-temperature ferroelectric semiconductor gas sensor, comprising the following steps: A test electrode is disposed on the upper surface of the substrate, and a heating electrode is disposed on the lower surface. A dispersion of α-In2Se3 nanosheets was coated onto the test electrode and the substrate surface not covered by the test electrode, and then dried to obtain an α-In2Se3 gas-sensitive layer. The α-In2Se3 gas-sensitive layer was subjected to corona polarization treatment to form a preset polarization state, thus obtaining the room temperature ferroelectric polarized semiconductor gas sensor.

[0008] Preferably, the preset polarization state can be dynamically controlled in real time by changing the parameters of the corona polarization treatment.

[0009] Preferably, the parameters for the above-mentioned corona polarization are: polarization voltage of 2000V~5000V and polarization time of 20min~40min.

[0010] Preferably, the thickness of the α-In2Se3 gas-sensitive layer is 0.8 μm to 2.5 μm.

[0011] Preferably, the concentration of the dispersion of the above-mentioned α-In2Se3 nanosheets is 1 mg / mL to 10 mg / mL.

[0012] Preferably, the above-mentioned α-In2Se3 nanosheets are prepared by liquid phase exfoliation.

[0013] Secondly, this application provides a room temperature ferroelectric semiconductor gas sensor, which is prepared by the above-described method.

[0014] Thirdly, this application provides a method for regulating the performance of a room-temperature ferroelectric semiconductor gas sensor, wherein the gas sensor is the aforementioned gas sensor, and the regulation method includes the following steps: The α-In2Se3 gas-sensitive layer of the above gas sensor is subjected to corona polarization treatment; By changing the polarization voltage and / or polarization time of the aforementioned corona polarization, the polarization state of the aforementioned α-In2Se3 gas-sensitive layer is dynamically controlled, thereby enabling the gas sensor to regulate the gas desorption rate.

[0015] Preferably, the parameters for the above-mentioned corona polarization are: polarization voltage of 2000V~5000V and polarization time of 20min~40min.

[0016] Fourthly, this application provides a gas sensor prepared by the above-described method or the application of the above-described gas sensor in the detection of nitrogen oxides, ammonia, chlorine or ozone.

[0017] In summary, the technical solutions conceived in this application have the following main technical advantages compared with the prior art: (1) This application forms an α-In2Se3 gas-sensitive layer by coating a dispersion of α-In2Se3 nanosheets onto the test electrode and the substrate surface not covered by the test electrode, and then subjecting it to corona polarization treatment. This makes the gas sensor exhibit excellent gas-sensitive performance for gases such as nitrogen oxides and ammonia at room temperature, with high selectivity and low false alarm rate. The response value is significantly improved and the detection limit is lower than ppb level. It also has good response recovery characteristics and long-term stability, making it suitable for applications such as room temperature, low cost, low power consumption, and trace gas detection.

[0018] (2) The fabrication process of the room temperature ferroelectric polarization semiconductor gas sensor provided in this application does not require high-temperature sintering or noble metal modification, is low in cost, and is suitable for large-scale production. At the same time, by simply adjusting the corona polarization parameters (voltage, time), the polarization state of the gas-sensitive layer and the gas detection sensitivity, response / recovery speed, and other performance characteristics determined therefrom can be dynamically and reversibly controlled, providing a brand-new technical approach for the development of intelligent tunable gas sensors. Attached Figure Description

[0019] Figure 1 This is a response curve of the room temperature ferroelectric semiconductor gas sensor provided in Embodiment 1 of this application to 500 ppb NO2 before and after polarization under room temperature conditions. Figure 2 This is a response curve of the room temperature ferroelectric semiconductor gas sensor provided in Embodiment 1 of this application to 10 ppm NO2 at room temperature after polarization. Figure 3 This is a response curve of the room temperature ferroelectric semiconductor gas sensor provided in Embodiment 1 of this application to 1~10 ppb NO2 at room temperature after polarization; Figure 4 This is a response curve of the room temperature ferroelectric polarization semiconductor gas sensor provided in Embodiment 1 of this application to 500 ppb NO before and after polarization at room temperature. Figure 5 This is a response curve of the room temperature ferroelectric semiconductor gas sensor provided in Embodiment 1 of this application to 2~10 ppm NO at room temperature after polarization; Figure 6 The room temperature ferroelectric polarized semiconductor gas sensor provided in Embodiment 1 of this application exhibits selectivity for nitrogen oxide gas and ammonia gas at room temperature after polarization. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0021] In the description of this application, it should be understood that the term "and / or" describes a relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. The symbol " / " in this document indicates that the related objects are in an "or" relationship; for example, A / B means A or B.

[0022] In the description of the embodiments in this application, the words "exemplary" or "for example" are used to indicate that they are examples, illustrations, or descriptions. Any embodiment or design that is described as "exemplary" or "for example" in the embodiments of this application should not be construed as being more preferred or advantageous than other embodiments or design options. Specifically, the use of the words "exemplary" or "for example" is intended to present the relevant concepts in a specific manner.

[0023] In the description of the embodiments in this application, unless otherwise stated, "multiple" means two or more.

[0024] This application provides a method for fabricating a room-temperature ferroelectric semiconductor gas sensor, comprising the following steps: A test electrode is disposed on the upper surface of the substrate, and a heating electrode is disposed on the lower surface. A dispersion of α-In2Se3 nanosheets was coated onto the test electrode and the substrate surface not covered by the test electrode, and then dried to obtain an α-In2Se3 gas-sensitive layer. The α-In2Se3 gas-sensitive layer was subjected to corona polarization treatment to form a preset polarization state, thus obtaining the room temperature ferroelectric polarized semiconductor gas sensor.

[0025] In this application, corona polarization treatment of the α-In₂Se₃ gas-sensitive layer enables the formation of a stable polarization electric field within the material, thereby modulating its surface band structure and charge distribution, significantly enhancing its adsorption and dissociation capabilities for nitrogen oxide gases. Specifically, during corona polarization, a high-voltage electric field induces the directional alignment of α-In₂Se₃ ferroelectric domains, forming a built-in electric field. This field promotes the separation and transport of charge carriers in the gas-sensitive layer, reduces the probability of electron-hole recombination, and enhances the charge transfer efficiency between gas molecules and the material surface, thus improving the sensor's response speed, sensitivity, and selectivity.

[0026] In practical applications, by changing the parameters of the aforementioned corona polarization treatment (such as polarization voltage and polarization time), the polarization intensity and spatial distribution of the α-In2Se3 gas-sensitive layer can be dynamically adjusted in real time, thereby achieving precise modulation of the sensor's gas-sensitive performance. For example, increasing the polarization voltage or extending the polarization time within a certain range can further enhance the polarization effect and improve the response value; conversely, by adjusting the parameters, a balance between response speed and recovery characteristics can be achieved to meet the needs of different application scenarios.

[0027] It is understood that this application does not have any particular limitation on the coating method or the number of coatings, as long as the dispersion of α-In2Se3 nanosheets can be uniformly coated. In some embodiments, the coating method may be, but is not limited to, drop coating, blade coating, spin coating, etc. To improve the ease of operation of the coating process, in some embodiments, the concentration of the dispersion of α-In2Se3 nanosheets may be 1 mg / mL to 10 mg / mL.

[0028] It is understood that this application does not limit the source of the above-mentioned α-In2Se3 nanosheet dispersion. It can be obtained by purchasing commercially available α-In2Se3 nanosheet dispersion, resuspending commercially available α-In2Se3 nanosheets in a solvent, or preparing the α-In2Se3 nanosheet dispersion in the laboratory.

[0029] In some embodiments, the α-In₂Se₃ nanosheets are prepared by liquid-phase exfoliation. In some embodiments, the preparation method of the α-In₂Se₃ nanosheet dispersion includes the following steps: mixing bulk α-In₂Se₃ and terpineol, followed by grinding and ultrasonic treatment to obtain the α-In₂Se₃ nanosheet dispersion. In some specific embodiments, the preparation process of the α-In₂Se₃ nanosheet dispersion is as follows: mixing bulk α-In₂Se₃ and terpineol, grinding in a mortar, then intermittently ultrasonicating the resulting mixture using an ultrasonic cell disruptor to exfoliate using cavitation, removing unexfoliated bulk particles, collecting the nanosheets in the supernatant, and then dispersing the nanosheets in terpineol to obtain the α-In₂Se₃ nanosheet dispersion.

[0030] In some embodiments, the drying temperature is 80°C to 90°C, and the drying time is 1 hour to 3 hours. It is understood that those skilled in the art can adapt the drying temperature by increasing or decreasing it, or extend or shorten the drying time according to experimental conditions, as long as the dispersion of α-In2Se3 nanosheets forms an α-In2Se3 gas-sensitive layer on the surface of the test electrode and the substrate not covered by the test electrode, all of which are within the scope of protection of this application.

[0031] In some embodiments, the thickness of the α-In2Se3 gas-sensitive layer is 0.8 μm to 2.5 μm.

[0032] In some embodiments, the polarization voltage of the above-mentioned corona polarization is 2000V~5000V, and the polarization time is 20min~40min. This makes the gas sensor made after the α-In2Se3 gas-sensitive layer is polarized have excellent selectivity and high response sensitivity to nitrogen oxides and ammonia at room temperature. This effectively avoids insufficient polarization of the α-In2Se3 gas-sensitive layer, which would affect the gas sensor's gas-sensitive response, or the α-In2Se3 gas-sensitive layer being broken down during the polarization process, resulting in the inability to obtain a gas sensor.

[0033] On the other hand, this application provides a room temperature ferroelectric polarized semiconductor gas sensor, namely a gas sensor based on polarization-controlled α-In2Se3, which is prepared by the above-described method.

[0034] This application also provides a method for performance regulation of a room-temperature ferroelectric semiconductor gas sensor, the method comprising the following steps: The α-In2Se3 gas-sensitive layer of the above gas sensor is subjected to corona polarization treatment; By changing the voltage and / or time of the corona polarization treatment, the polarization state of the α-In2Se3 gas-sensitive layer can be dynamically controlled, thereby enabling the gas sensor to regulate the gas desorption rate.

[0035] In some embodiments, the voltage of the corona polarization is 2000V~5000V, and the corona polarization time is 20min~40min.

[0036] This application also provides a gas sensor prepared by the above method or the application of the above gas sensor in the detection of nitrogen oxides, ammonia, chlorine or ozone.

[0037] In some embodiments, the aforementioned nitrogen oxide gas includes nitrogen dioxide and nitric oxide.

[0038] It should be understood that materials of the same or similar type, model, quality, properties, or function as the reagents and instruments used in the following embodiments can be used to implement this application. Unless otherwise specified, the experimental methods used in the following embodiments are conventional methods. Unless otherwise specified, the materials and reagents used in the following embodiments are commercially available.

[0039] The following are examples and comparative examples: Example 1 The room-temperature ferroelectric semiconductor gas sensor provided in this embodiment is fabricated by the following steps: (1) Place the blocky α-In2Se3 in terpineol and grind it in an agate mortar for 30 min. Then, place the mixture obtained by grinding in an ultrasonic cell disruptor and sonicate for 2 h to perform liquid phase exfoliation to obtain an α-In2Se3 nanosheet dispersion with a concentration of 4 mg / mL.

[0040] (2) The above α-In2Se3 nanosheet dispersion was drop-coated onto the upper surface of a sensor substrate with a heating electrode at the bottom and a pair of interdigitated Au test electrodes on the upper surface using a pipette. Then, the dispersion was uniformly coated with a scraper to completely cover the substrate and the test electrodes. The substrate was dried in a vacuum oven at 85°C for 3 hours to remove terpineol, so that an α-In2Se3 gas-sensitive layer with a thickness of 1 μm was formed on the upper surface of the substrate and the part of the substrate not covered by the test electrodes, thus obtaining a planar device coated with an α-In2Se3 gas-sensitive layer.

[0041] (3) Based on the packaging process of TO devices, the above planar devices are soldered onto a hexagonal base using wire pads, then packaged, and then placed on the copper disk of a corona polarizer (purchased from Wuhan Bailibo Technology Co., Ltd., model SPD20KVCP). The polarization of the α-In2Se3 gas-sensitive layer is controlled by applying a polarization voltage of 4000V and the polarization time is 20min, thus obtaining a room temperature ferropolar polarized semiconductor gas sensor.

[0042] The aforementioned ferroelectric polarized semiconductor gas sensor was placed in an experimental circuit. A Keithley 6487 picoammeter was used to continuously monitor the resistance changes of the gas sensor under background gas (air) and target gas (nitrogen oxides) at room temperature. The measurement curves were displayed in real time on a computer. The response value is the ratio of the resistance (Ra) between a pair of interdigitated Au electrodes in air to the resistance (Rg) in nitrogen oxide gas (NO2 or NO), to evaluate the gas sensor's gas-sensing response to nitrogen oxides (Rg / Ra). The test results are as follows: Figures 1-5 As shown.

[0043] Figure 1 The response curves of the ferroelectric polarized semiconductor gas sensor to 500 ppb NO2 at room temperature before and after polarization show that before polarization, the gas sensor's response time to 500 ppb NO2 at room temperature is 236 s and the response value is only 2.35; after polarization, the gas sensor's response time to 500 ppb NO2 at room temperature is reduced to 202 s and the response value increases to 12.55.

[0044] Figure 2 The response curve of the ferroelectric polarized semiconductor gas sensor to 10 ppm NO2 at room temperature after polarization shows that the response value is as high as 1544.06.

[0045] Figure 3 The response curves of the ferroelectric polarized semiconductor gas sensor to 1~10 ppb NO2 at room temperature after polarization show that the actual detection limit of the gas sensor for NO2 gas can reach 1 ppb, and the response value can reach 1.18. At the same time, the response value increases continuously with the increase of NO2 gas concentration, indicating that the gas sensor has good response characteristics to NO2.

[0046] Figure 4 The response curves of the ferroelectric polarized semiconductor gas sensor to 500 ppb NO at room temperature before and after polarization show that before polarization, the gas sensor has a response time of 223 s and a response value of 16.71 at room temperature; after polarization, the response time of the gas sensor to 500 ppb NO at room temperature is reduced to 205 s and the response value increases to 32.07.

[0047] Figure 5 The response curves of the ferroelectric polarized semiconductor gas sensor to 2~10 ppm NO at room temperature after polarization show that the response value is as high as 825.9 when the NO concentration is only 2 ppm, indicating that the gas sensor has excellent response characteristics to NO.

[0048] Furthermore, using the above testing method, the selectivity of the ferroelectric polarized semiconductor gas sensor prepared in this embodiment for nitrogen oxides and ammonia was evaluated by changing the target gas (the target gases were NO2, NO, NH3, triethylamine, acetaldehyde, H2, acetone, CH4, CO, formaldehyde, n-heptane, C2H2, C2H6, m-diphenylamine, and ethyl acetate, respectively). The test results are as follows: Figure 6 As shown.

[0049] Figure 6 The bar chart shows the response of the ferroelectric semiconductor gas sensor to various gases at room temperature after polarization. The concentration of the target gases is 10 ppm. It can be seen that the response values ​​of the gas sensor to nitrogen oxides (NO2, NO) and NH3 are much higher than those of other gases (triethylamine, acetaldehyde, H2, acetone, CH4, CO, formaldehyde, n-heptane, C2H2, C2H6, m-diphenylamine, ethyl acetate). This indicates that the room temperature ferroelectric semiconductor gas sensor provided in this embodiment has high sensitivity and selectivity to nitrogen oxides (NO2, NO) and NH3.

[0050] Example 2 The room-temperature ferroelectric semiconductor gas sensor provided in this embodiment is fabricated by the following steps: (1) Prepare α-In2Se3 nanosheet dispersion according to the method provided in Example 1.

[0051] (2) An α-In2Se3 gas-sensitive layer is formed on the electrode surface of the TO device according to the method provided in Example 1.

[0052] (3) The TO device with an α-In2Se3 gas-sensitive layer formed on the electrode surface is placed on the copper disk of the corona polarizer. The polarization of the α-In2Se3 gas-sensitive layer is controlled by applying different polarization voltages (1000V, 2000V, 3000V, 4000V, 5000V, 6000V) for 20 min to obtain a room temperature ferropolar polarized semiconductor gas sensor.

[0053] Following the test method provided in Example 1, the ferroelectric polarized semiconductor gas sensors obtained by different polarization voltage treatments were placed in an experimental circuit, and their gas-sensing response (Rg / Ra) to 500 ppb NO2 gas was tested at room temperature.

[0054] Experiments showed that when the polarization voltage was below 2000V, the response value of the fabricated ferroelectric polarized semiconductor gas sensor to 500ppb NO2 gas at room temperature was below 2.35; when the polarization voltage was above 5000V, the α-In2Se3 gas-sensitive layer was broken down during the polarization process.

[0055] When the polarization voltage is between 2000V and 5000V, the obtained ferroelectric polarized semiconductor gas sensor exhibits a response value greater than 10 for 500ppb NO2 gas at room temperature. Furthermore, when the polarization voltage is 4000V, the obtained ferroelectric polarized semiconductor gas sensor achieves a response value of 14.1 for 500ppb NO2 gas at room temperature, which is six times the response value of the unpolarized sensor for 500ppb NO2 gas.

[0056] Comparative Example 1 The room-temperature ferroelectric semiconductor gas sensor provided in this comparative example is fabricated using the following steps: (1) The polarization of bulk α-In2Se3 was controlled by applying a polarization voltage of 4000V using a corona polarizer for 20 min. Then, the polarized bulk α-In2Se3 was ground and ultrasonically treated according to the method provided in Example 1 to obtain a polarized α-In2Se3 nanosheet dispersion.

[0057] (2) Following the method provided in Example 1, the above-mentioned polarized α-In2Se3 nanosheet dispersion was drop-coated onto the upper surface of the sensor substrate and dried to obtain a planar device coated with a polarized α-In2Se3 gas-sensitive layer. Then, based on the packaging process of TO devices, the above-mentioned planar device was soldered onto a hexagonal base using wire pads and packaged to obtain a room temperature ferropolar polarized semiconductor gas sensor.

[0058] Following the testing method provided in Example 1, the ferroelectric polarized semiconductor gas sensor prepared in this comparative example was placed in an experimental circuit, and its gas-sensing response (Rg / Ra) to 500 ppb NO2 gas was tested at room temperature.

[0059] Experiments revealed that the ferroelectric polarized semiconductor gas sensor prepared in this comparative example exhibited a significantly lower response value to 10 ppm NO2 gas at room temperature compared to Example 1. The reason for this may be that the process sequence of first polarizing the bulk α-In₂Se₃ and then fabricating it into a nanosheet dispersion disrupted the long-range ordered structure required for the ferroelectricity of the two-dimensional material. This caused the pre-established internal electric field and ferroelectric domain arrangement to be destroyed during the stripping step, resulting in relaxation of the macroscopic polarization state. Ultimately, this led to a lack of an effective built-in electric field within the coated gas-sensitive layer, preventing the formation of a continuous electrical pathway and a synergistic ferroelectric domain network. Consequently, the polarization enhancement effect could not be achieved, and the gas-sensing performance was not improved.

[0060] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A method for fabricating a room-temperature ferroelectric semiconductor gas sensor, characterized in that, Includes the following steps: A test electrode is disposed on the upper surface of the substrate, and a heating electrode is disposed on the lower surface. A dispersion of α-In2Se3 nanosheets was coated onto the test electrode and the substrate surface not covered by the test electrode, and then dried to obtain an α-In2Se3 gas-sensitive layer. The α-In2Se3 gas-sensitive layer is subjected to corona polarization treatment to form a preset polarization state, thereby obtaining the room temperature ferroelectric polarized semiconductor gas sensor.

2. The preparation method according to claim 1, characterized in that, The preset polarization state can be dynamically controlled in real time by changing the parameters of the corona polarization treatment.

3. The preparation method according to claim 1 or 2, characterized in that, The parameters for corona polarization are: polarization voltage of 2000V~5000V and polarization time of 20min~40min.

4. The preparation method according to claim 1, characterized in that, The thickness of the α-In2Se3 gas-sensitive layer is 0.8 μm to 2.5 μm.

5. The preparation method according to claim 1 or 4, characterized in that, The concentration of the dispersion of the α-In2Se3 nanosheets is 1 mg / mL to 10 mg / mL.

6. The preparation method according to claim 5, characterized in that, The α-In2Se3 nanosheets were prepared by liquid phase exfoliation.

7. A room-temperature ferroelectric semiconductor gas sensor, characterized in that, It is prepared by the preparation method according to any one of claims 1 to 6.

8. A method for regulating the performance of a room-temperature ferroelectric semiconductor gas sensor, wherein the gas sensor is the gas sensor according to claim 7, characterized in that, The control method includes the following steps: The α-In2Se3 gas-sensitive layer of the gas sensor is subjected to corona polarization treatment; By changing the polarization voltage and / or polarization time of the corona polarization, the polarization state of the α-In2Se3 gas-sensitive layer can be dynamically controlled, thereby enabling the gas sensor to regulate the gas desorption rate.

9. The control method according to claim 8, characterized in that, The polarization voltage of the corona polarization is 2000V~5000V, and the polarization time is 20min~40min.

10. The application of a gas sensor prepared by any one of claims 1 to 6 or the gas sensor of claim 7 in the detection of nitrogen oxides, ammonia, chlorine or ozone.

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